Miscellany

Jai Ganesh · 2025-03-01 00:03:14

2375) Polyurethane foam

Gist

Polyurethane foam is used as a thermal insulator in construction; appliances such as refrigerator, insulated products (thermoware) such as thermos bottles and cool boxes; and automobiles (in arm rests, doors and seats). It is also used to produce panels, slab-stock, cushions, mattresses and packaging materials.

Polyurethane foam is soft, less dense foam. It is considered open-cell, meaning that the cells that make up the actual material are not cross-linked. This means air can freely flow through them, which results in a foam that gives a lot when pressure is applied to it.

Polyurethane Foam refers to a type of foam formed by the reaction of polyols and isocyanates, ranging from rigid insulating materials to flexible cushioning materials used in various applications such as construction, furniture, bedding, and packaging.

Summary

Polyurethane foam is one component, curing with moisture in air, expanding while curing, semi-rigid in aerosol form for installation, grouting and insulation material.

Flexible Polyurethane Foams are used mainly for assembly of doors and windows, infilling applications, sound and heat insulations, waterproof barriers and insulation against fire. Polyurethane Foam reacts rapidly with moisture in the air and expands after application. Polyurethane bonds extremely well to the surfaces applied thanks to its high adhesion power.

Where are They Used?

Door and window assembly is the most effective usage areas of PU Foams. It is used for the insulation of electricity installations, hot and cold water pipes, adhesion of roofing tiles, tightness of terraces, concrete shear wall buildings, industrial roof insulation, cold storage houses and ice plants, decks of ship and yacht, filling of the voids between external thermal insulation materials, adhesion of insulation materials, filling of the voids and insulation of dry food storages.

What are the PU Foam Types?

Polyurethane foams may be divided into two sections depending on its application type and purpose.

1- PU Foams according to their Application Type;

Foams with Straw: It may be called as type of most frequent and best seller foam in the market. It is used with the straw apparatus supplied with each canister. It is preferred for filling broad voids (average 200% - 250%) due to its high expansion rate. Akfix Maximum PU Foam 805, 940, 806, 840, 820 coded products are preferred for the foam applications with straw.

Foams with Pistoles (Professional): It is used with a special application gun. The product mostly addresses the professionals. It is preferred to fill relatively narrow voids due to its low expansion rate (average %0%-60%). Akfix foams with guns having codes of 805P, 850, 840P, 820P offer an effective solution for filling small voids.

2- PU Foams in Accordance with Their Intended Use;

Foams for Filling Voids: It is standard and most frequently used foam type.

Adhesion Foams: These are the foams having increased adhesive property due to having very low (minimal) expansion rates compared to standard foams and denser polymer. Heat insulation materials like EPX, XPS, aerated concrete, brick and different construction materials like marble may be bonded with these products. For these group of products; Akfix 960, 960P, 962P coded products are preferred.

Contribution of Polyurethane Foams to Sound, Heat and Water Insulation;

It is required to apply PU Foam accurately for a good insulation.

Sound Insulation

They are used for filling voids between materials used for sound insulation, door and window voids, preventing passing of sound, heat and air, insulation the environment of the vent ducts, chimneys and climatic units protruding from the buildings and many more similar fields.

Heat insulation

2 components rigid (strong) foams are preferred for heat insulation. Akfix 812 PU foam developed for low temperatures - like 25° C degree and Akfix 885 PU Foam for up to -25° C degree temperature ensure a perfect heat insulation even under very challenging conditions.

Water insulation

Water can in no way damage the foam that is properly applied and cured completely. One component polyurethane foams are preferred for external environment applications, decorative pools, attaching decorative stones to each other, preventing water leakage from joints of the mechanisms like climatic units on caravan type vehicles and antennas. Akfix polyurethane foams provide long life and effective solution for sound, heat and water insulation applications.

Frequently Asked Questions:

How long PU Foam can last?

How long the structure stands as long as it does not expose intense UV lights. UV lights cause deformation of the foam corrupting its structure. Dried foam can be protected from hazardous lights by painting surface.

Does moisture, wetness, bleeding, humidity occur at the places where rigid spray foam is applied?

Rigid foam is applied to roofs of buildings and have a perfect heat insulation capability. One living on the top floor does not feel moisture, humidity and therefore molding in case if there is no point in another place that may create thermal bridge.

Is Polyurethane Foam flammable?

There are fire resistant foams in fire classifications of B1 and B2 according to German Standard DIN 4102 and these products resist against the fire for a certain time when exposed to flame directly or remain in a place where fire continues. Akfix B1, B2 Foams resist against the fire up to 217 minutes. Akfix 820, 820P, 840, 840P coded foams are preferred among fire resistant products.

How is it cleaned?

The most practical way to clean wet foam is to use foam cleaner. The foam that is contaminated around during application may be removed from all building materials, skin, textile products by spraying foam cleaner on it before it gets dried. It is possible to clean foam residues easily with Akfix 800C foam cleaner. Acetone can also be used in case where foam cleaner is not available. Cured foam can only be cleaned by mechanical ways like utility knife etc.

Which Names Are They Referred By In The World?

Names commonly used in the market; one component pu foam, polyurethane pu foam, OCF pu foam sealant, gap filling pu foam, window assembling pu foam, mounting pu foam, montage pu foam, heat insulation pu foam, sound isolation pu foam, door assembling pu foam, Insulation foam, construction foam.

Details

Polyurethane foam is a solid polymeric foam based on polyurethane chemistry. As a specialist synthetic material with highly diverse applications, polyurethane foams are primarily used for thermal insulation and as a cushioning material in mattresses, upholstered furniture or as seating in vehicles. Its low density and thermal conductivity combined with its mechanical properties make them excellent thermal and sound insulators, as well as structural and comfort materials.

Polyurethane foams are thermosetting polymers. They cannot be melted and reshaped after initially formed, because the chemical bonds between the molecules in the material are very strong and are not broken down by heating. Once cured and cooled, the material maintains its shape and properties.

Classification of polyurethane foams
Polyurethane foams are the most widely used representatives of thermoset foams. Depending on their cellular structure, they can be classified as open or closed-cell foams. Looking at mechanical properties, there are two main types of polyurethane foam; flexible (soft) and rigid (hard) foams. Generally speaking, flexible polyurethane foams have an open-cell structure where the pores are interconnected, smaller in size and irregularly shaped; contrary to rigid polyurethane foams that have a closed-cell structure, where the pores are not interconnected. The market share between these two types is largely equal.

There are various processing technologies in the production of polyurethane foams. Depending on the properties of the end application, the two most often used at large scale production are moulding and slabstock (block) foaming. Next to these, other prominent types include cavity-filling foam (e.g. car fillings used for acoustic insulation); and spray foam (e.g. roof thermal insulation). These are known as semi-flexible foams behind appropriate overlays.

Flexible polyurethane foam

The flexible polyurethane foam (FPUF) is produced from the reaction of polyols and isocyanates, a process pioneered in 1937. Depending on the application the foam will be used for, a series of additives are necessary to produce high-quality PU foam products. FPUF is a versatile material that can be tailored to exhibit different properties. It allows for superior compression, load-bearing and resilience that provides a cushioning effect. Because of this property, lightweightness, and efficient production process, it is often used in furniture, bedding, automotive seating, athletic equipment, packaging, footwear, and carpets.

Flexible polyurethane foams with a high volume of open pores have been greatly regarded as an effective noise absorption material and are widely used as acoustic insulation in various sectors, from construction to transportation. It is also a very resilient material that does not deteriorate over time and its lifetime is typically linked to the lifetime of the application it is used in.

Types of Flexible Polyurethane Foams based on Manufacturing Technology

Flexible polyurethane foams can be manufactured through a continuous (slabstock) production or moulding process. In the continuous process, the mixed ingredients are poured on the conveyor belt. The chemical reaction occurs instantly, causing the foam to rise within seconds and then solidify. In theory, foam blocks of several kilometres in length could be produced this way. In reality, the foam blocks are typically cut at a length of between 15 and 120m, cured and stored for further processing.

Contrary to slabstock foam, moulded foam production is a discontinuous process. Moulded foam articles are made one at a time by injecting the foam mixture into moulds. When the foam rises and expands, it occupies the whole space in the mould. It solidifies almost instantly and the produced part can then be removed from the mould, either mechanically or manually. This is the biggest advantage of moulded PU foams – they can be moulded into specific desired shapes, eliminating the need for cutting and reducing waste fractions. They can be produced with multiple zones of hardness and with reinforcements for further easier assembly. This is why moulded foam technology is widely used in the production of seat cushions used in the transport industries.

Based on the production process, other types of flexible polyurethane foams may include rebonded (or recycled), reticulated and auxetic PU foams.

Sustainability of Flexible Polyurethane Foams

Since the invention of polyurethane chemistry there have been constant innovations in the industry, driven by the need to decrease the toxicity of chemical substances used in production processes. Some examples include reducing Volatile Organic Compounds emissions or using blowing agents with a lower global warming potential (GWP) as well as ozone-depleting potential (ODP).

In the last decades, the main focus of the FPUF industry has been improving the environmental impact of its products and processes. A cradle-to-gate analysis of flexible (TDI slabstock) PU foam shows that (by far) the largest effect on the life cycle of the PU foams is due to raw materials extraction and production. Depending on the parameters, these account for about 90% of the total Greenhouse Gas (GHG) emissions.

Traditionally nearly all raw materials used for flexible PU foam production have been of fossil origin. Today, it is possible to make flexible PU foams from alternative, non-fossil sources, thus significantly improving its environmental footprint. These include bio-polyols, recycled polyols and CO2-based polyols.

As a thermosetting polymer PU foam cannot just be melted at the end of its useful life to make new products. For PU foam-containing products, there are various recycling technologies available and in broad use today:

* Physical (or mechanical) recycling. Physical recycling changes the physical properties of the material to a form more suitable for further processing. With this recycling process, the chemical composition of the PU material is not changed. The most common method is called rebonding, in which the flexible PU foam (production cut-offs and end-of-life foam) is transformed into so-called trim (foam flocks), which in turn can become rebonded foam used in products such as: e.g. carpet underlay, gym mats, acoustic insulation, as well as mattresses and furniture cushioning. Other types of mechanical recycling of PU foam include regrinding (powdering), compression moulding and adhesive pressing of powdered PU waste. For example, regrinding includes shredding PU material into a fine powder and mixing it as filler with a polyol component to make new PU foams
* Chemical recycling (or depolymerisation). Chemical recycling methods are focused on recovering monomers, which can be used to synthesise new polymers. The chemical composition of the waste PU foam is changed by breaking down and reforming the targeted bonds, to recover the original raw materials. Flexible polyurethane foam is broken down into its specific constituent chemical raw materials, which can be used again to make fresh foam. Technology has been in use at an industrial scale (in Europe) since 2013 for post-industrial flexible PU foam. Differentiated by the base material used to dissolve PU foam, depolymerisation technologies include hydrolysis, aminolysis, alcoholysis and glycolysis.
* Feedstock (or thermo-chemical) recovery. Feedstock recycling includes thermal processing of (often) mixed waste materials (of which PU can be one constituent), disintegrating them at a molecular level and recovering synthesis (syngas) and fuel gas - products which can be further used as new raw materials for the petrochemical industry. Mass balance accounting is needed to account for recycled materials. For applications that are too difficult to dismantle or too contaminated to recycle, thermo-chemical recycling is the best option. This technology in particular allows the production of new “virgin-equivalent” raw materials, which are specifically appropriate for the production of applications that need to comply with stringent requirements, e.g. in the automotive industry.

Globally today the most often used waste management methods are landfilling and energy recovery. These should only be used when recycling methods are not available or cost-effective. Energy recovery processes include combustion, incineration and thermal degradation of PU.

Rigid polyurethane foams

Rigid polyurethane foam has many desirable properties which has enabled increased use in various applications, some of which are quite demanding. These properties include low thermal conduction making it useful as an insulator. It also has low density compared to metals and other materials and also good dimensional stability. A metal will expand on heating whereas rigid PU foam does not. They have excellent strength to weight ratios. Like many applications, there has been a trend to make rigid PU foam from renewable raw materials in place of the usual polyols.

They are used in vehicles, planes and buildings in structural applications. They have also been used in fire-retardant applications.

Space shuttles

Polyurethane foam has been widely used to insulate fuel tanks on Space Shuttles. However, it requires a perfect application, as any air pocket, dirt or an uncovered tiny spot can knock it off due to extreme conditions of liftoff. Those conditions include violent vibrations, air friction and abrupt changes in temperature and pressure. For a perfect application of the foam there have been two obstacles: limitations related to wearing protective suits and masks by workers and inability to test for cracks before launch, such testing is done only by naked eye. The loss of foam caused the Space Shuttle Columbia disaster. According to the Columbia accident report, NASA officials found foam loss in over 80% of the 79 missions for which they have pictures.

By 2009 researchers created a superior polyimide foam to insulate the reusable cryogenic propellant tanks of Space Shuttles.

Additional Information

Polyurethane is any of a class of synthetic resinous, fibrous, or elastomeric compounds belonging to the family of organic polymers made by the reaction of diisocyanates (organic compounds containing two functional groups of structure ―NCO) with other difunctional compounds such as glycols. The best known polyurethanes are flexible foams—used as upholstery material, mattresses, and the like—and rigid foams—used for such lightweight structural elements as cores for airplane wings.

Foamed polyurethanes result from the reaction of diisocyanates with organic compounds, usually polyesters, containing carboxyl groups; these reactions liberate bubbles of carbon dioxide that remain dispersed throughout the product. Use of polyethers or polyesters containing hydroxyl groups in preparing polyurethanes results in the formation of elastomeric fibres or rubbers that have outstanding resistance to attack by ozone but are vulnerable to the action of acids or alkalies.

In textiles the synthetic fibre known generically as spandex is composed of at least 85 percent polyurethane by weight. Such fibres are generally used for their highly elastic properties. Trademarked fibres in this group are Lycra, Numa, Spandelle, and Vyrene. Such fibres have, for many textile purposes, largely replaced natural and synthetic rubber fibres.

Although somewhat weak in the relaxed state, spandex fibres can be stretched about 500–610 percent beyond their original length without breaking and quickly return to their original length. The fibre, usually white with dull lustre, is readily dyed. It absorbs very little moisture. It melts at about 250° C (480° F) and yellows upon prolonged exposure to heat or light. Items made of spandex can be machine washed and dried at moderate temperatures. Use of chlorine bleach can produce yellowing. Spandex fibres are frequently covered with other fibres such as nylon.

Spandex is used in such apparel as foundation garments, support hosiery, and swimsuits. It is light in weight and cool; it is resistant to deterioration from body acids; and it is easily laundered and quick-drying.

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Jai Ganesh · 2025-03-02 00:05:58

2376) Birthday

Gist

Birthday refers to the exact date of your birth (dd/mm/yyyy), The day you came to this world whereas Birth Anniversary is what we celebrate that particular day (dd/mm) every year. But we use the term "Birthday" in place of "Birth Anniversary" .

Summary

Annual celebrations and commemorations came about with the invention of the calendar. Not much is known about the first birthday celebrations in history, in part because they are very ancient. The earliest ones we know about were for nobles, in which the celebration played a performative social function that celebrated the noble as a leader. The use of the date of birth for such celebrations was somewhat arbitrary; other dates, such as the date of coronation or the annual festival of a patron deity, were common as well.

The tradition of celebrating everyone's birthday is fairly recent. It coincided with several socioeconomic trends in the 19th and 20th centuries that saw the rise of consumerism and increased investment in the upbringing of children—and, thus, the annual celebration of their lives through the giving of gifts.

Details

A birthday is the anniversary of the birth of a person, or figuratively of an institution. The birthdays of people are celebrated in numerous cultures, often with birthday gifts, birthday cards, a birthday party, or a rite of passage.

Many religions celebrate the birth of their founders or religious figures with special holidays (e.g. Christmas, Mawlid, Buddha's Birthday, Krishna Janmashtami, and Gurpurb).

There is a distinction between birthday and birthdate (also known as date of birth): the former, except for February 29, occurs each year (e.g. January 15), while the latter is the complete date when a person was born (e.g. January 15, 2001).

Legal conventions

In most legal systems, one becomes a legal adult on a particular birthday when they reach the age of majority (usually between 12 and 21), and reaching age-specific milestones confers particular rights and responsibilities. At certain ages, one may become eligible to leave full-time education, become subject to military conscription or to enlist in the military, to consent to sexual intercourse, to marry with parental consent, to marry without parental consent, to vote, to run for elected office, to legally purchase (or consume) alcohol and tobacco products, to purchase lottery tickets, or to obtain a driver's licence. The age of majority is when minors cease to legally be considered children and assume control over their persons, actions, and decisions, thereby terminating the legal control and responsibilities of their parents or guardians over and for them. Most countries set the age of majority at 18, though it varies by jurisdiction.

Cultural conventions

Many cultures have one or more coming of age birthdays:

* In Canada and the United States, families often mark a girl's 16th birthday with a "sweet sixteen" celebration – often represented in popular culture.
* In some Hispanic countries, as well as Brazil, the quinceañera (Spanish) or festa de quinze anos (Portuguese) celebration traditionally marks a girl's 15th birthday.
* In the Philippines, a coming-of-age party called a debut is held for young women on their 18th birthday and young men on their 21st birthday.
* In some Asian countries that follow the zodiac calendar, there is a tradition of celebrating the 60th birthday.
* In Korea, many celebrate a traditional ceremony of Baek-il (Feast for the 100th day) and Doljanchi (child's first birthday).
* In Japan, people celebrate a Coming of Age Day for all those who have turned 18.
* In British Commonwealth nations, cards from the Royal Family are sent to those celebrating their 100th and 105th birthday and every year thereafter.
* In Ghana, on their birthday, children wake up to a special treat called "oto" which is a patty made from mashed sweet potato and eggs fried in palm oil. Later they have a birthday party where they usually eat stew and rice and a dish known as "kelewele", which is fried plantain chunks.
* Jewish boys have a bar mitzvah on their 13th birthday. Jewish girls have a bat mitzvah on their 12th birthday, or sometimes on their 13th birthday in Reform and Conservative Judaism. This marks the transition where they become obligated in commandments from which they were previously exempted and are counted as part of the community.

Historically significant people's birthdays, such as national heroes or founders, are often commemorated by an official holiday marking the anniversary of their birth.

* Catholic saints are remembered by a liturgical feast on the anniversary of their "birth" into heaven a.k.a. their day of death. The ancient Romans marked the anniversary of a temple dedication or other founding event as a dies natalis, a term still sometimes applied to the anniversary of an institution (such as a university).

An individual's Beddian birthday, named in tribute to firefighter Bobby Beddia, occurs during the year that their age matches the last two digits of the year they were born.

In many cultures and jurisdictions, if a person's real birthday is unknown (for example, if they are an orphan), their birthday may be adopted or assigned to a specific day of the year, such as January 1. The birthday of Jesus is celebrated at Christmas. Racehorses are reckoned to become one year old in the year following their birth on January 1 in the Northern Hemisphere and August 1 in the Southern Hemisphere.

Traditions

In certain parts of the world, an individual's birthday is celebrated by a party featuring a specially made cake. It may be decorated with lettering and the person's age, or studded with the same number of lit candles as the age of the individual. The celebrated individual may make a silent wish and attempt to blow out the candles in one breath; if successful, superstition holds that the wish will be granted. In many cultures, the wish must be kept secret or it will not "come true".

Presents are bestowed on the individual by the guests appropriate to their age. Other birthday activities may include entertainment (sometimes by a hired professional, i.e., a clown, magician, or musician) and a special toast or speech by the birthday celebrant. The last stanza of Patty Hill's and Mildred Hill's famous song, "Good Morning to You" (unofficially titled "Happy Birthday to You") is typically sung by the guests at some point in the proceedings. In some countries, a piñata takes the place of a cake.

Name days

In some historically Roman Catholic and Eastern Orthodox countries, it is common to have a 'name day', otherwise known as a 'Saint's day'. It is celebrated in much the same way as a birthday, but it is held on the official day of a saint with the same Christian name as the birthday person; the difference being that one may look up a person's name day in a calendar, or easily remember common name days (for example, John or Mary); however in pious traditions, the two were often made to concur by giving a newborn the name of a saint celebrated on its day of confirmation, more seldom one's birthday. Some are given the name of the religious feast of their christening's day or birthday, for example, Noel or Pascal (French for Christmas and "of Easter"); as another example, Togliatti was given Palmiro as his first name because he was born on Palm Sunday.

Official birthdays

Some notables, particularly monarchs, have an official birthday on a fixed day of the year, which may not necessarily match the day of their birth, but on which celebrations are held. Examples are:

* Jesus Christ's traditional birthday is celebrated as Christmas Eve or Christmas Day around the world, on December 24 or 25, respectively. As some Eastern churches use the Julian calendar, December 25 will fall on January 7 in the Gregorian calendar. These dates are traditional and have no connection with Jesus's actual birthday, which is not recorded in the Gospels.
* Similarly, the birthdays of the Virgin Mary and John the Baptist are liturgically celebrated on September 8 and June 24, especially in the Roman Catholic and Eastern Orthodox traditions (although for those Eastern Orthodox churches using the Julian calendar the corresponding Gregorian dates are September 21 and July 7 respectively). As with Christmas, the dates of these celebrations are traditional and probably have no connection with the actual birthdays of these individuals.
* The King's Official Birthday or Queen's Official Birthday in Australia, Fiji, Canada, New Zealand, and the United Kingdom.
* The Grand Duke's Official Birthday in Luxembourg is typically celebrated on June 23. This is different from the monarch's date of birth, April 16.
* Koninginnedag in the Kingdom of the Netherlands was typically celebrated on April 30. Queen Beatrix fixed it on her mother's birthday, the previous queen, to avoid the winter weather associated with her own birthday in January. The present monarch's birthday is 27 April, and it is also celebrated on that day. This has replaced the 30th of April celebration of Koninginnedag.
* The previous Japanese Emperor Showa (Hirohito)'s birthday was April 29. After his death, the holiday was kept as "Showa no Hi", or "Showa Day". This holiday falls close to Golden Week, the week in late April and early May.
* Kim Il Sung and Kim Jong Il's birthdays are celebrated in North Korea as national holidays called the Day of the Sun and the Day of the Shining Star respectively.
* Washington's Birthday, commonly referred to as Presidents' Day, is a federal holiday in the United States that celebrates the birthday of George Washington. President Washington's birthday is observed on the third Monday of February each year. However, his actual birth date was either February 11 (Old Style), or February 22 (New Style).
* In India, every year, October 2, which marks the Birthday of Mahatma Gandhi, is declared a holiday. All liquor shops are closed across the country in honor of Gandhi, who did not consume liquor.
* Martin Luther King Jr. Day is a federal holiday in the United States marking the birthday of Martin Luther King Jr.. It is observed on the third Monday of January each year, around the time of King's birthday, January 15.
* Mawlid is the official birthday of Muhammad and is celebrated on the 12th or 17th day of Rabi' al-awwal by adherents of Sunni and Shia Islam respectively. These are the two most commonly accepted dates of birth of Muhammad.

Jai Ganesh · 2025-03-03 00:03:00

2377) Lexicographer

Gist

A lexicographer studies words and compiles the results into a dictionary. This is one of several words for a certain type of writer or editor. Just as a playwright writes plays and a poet writes poems, a lexicographer puts together dictionaries.

A lexicographer is a professional that writes and edits dictionaries by researching new words, finding the meaning of existing words and translating expressions and words amongst others.

Ever wonder who writes dictionaries? They're called lexicographers. A lexicographer studies words and compiles the results into a dictionary.

This is one of several words for a certain type of writer or editor. Just as a playwright writes plays and a poet writes poems, a lexicographer puts together dictionaries. Lexicographer come up with definitions, determines parts of speech, gives pronunciations, and sometimes provides example sentences. Lexicographer need to do a lot of research to make sure they're defining a word correctly; dictionaries are books that people need to trust. If you love words, you might enjoy being a lexicographer.

Summary

Becoming a Lexicographer: A Comprehensive Guide

If you have a passion for language and a love for words, a career as a lexicographer might be the perfect fit for you. Lexicography is the art and science of compiling dictionaries, and it plays a crucial role in preserving and shaping language. In this comprehensive guide, we will explore the fascinating world of lexicography, from understanding its importance to finding your path in this unique and rewarding field.

Understanding Lexicography

Have you ever wondered who is responsible for creating the dictionaries you use every day? Lexicographers are linguistic experts who specialize in compiling, editing, and researching words and their meanings. They play a vital role in documenting and defining the ever-evolving English language.

Lexicography is a fascinating field that delves deep into the intricacies of language. It involves not only the compilation of words but also the exploration of their origins, meanings, and usage. Lexicographers are like detectives, uncovering the hidden stories behind the words we use.

The Role and Importance of a Lexicographer:

Role of a lexicographer

Lexicographers are guardians of our language, ensuring that words are accurately defined and recorded. They painstakingly research the etymology and usage of words, staying up to date with new words and phrases that enter the lexicon. Their work forms the foundation of our understanding and communication.

Lexicographers have a profound impact on society by shaping the way we communicate. They provide us with the tools to express ourselves effectively and to comprehend the thoughts and ideas of others. Without lexicographers, our language would lack structure and clarity.

The Evolution of Lexicography

Lexicography has come a long way from the days of traditional dictionaries. Modern lexicographers now harness the power of technology and the vastness of the internet to create comprehensive and dynamic resources. The advent of corpus linguistics has revolutionized the way lexicographers analyze language usage, providing valuable insights into the semantic and syntactic patterns of words.

Corpus linguistics involves the study of large collections of written and spoken texts, known as corpora. Lexicographers use these corpora to identify patterns of word usage, helping them determine the most common meanings and collocations of words. This data-driven approach ensures that dictionaries are not only descriptive but also reflective of how language is actually used.

Furthermore, the internet has opened up new possibilities for lexicographers. Online dictionaries can be constantly updated, ensuring that they remain relevant in a rapidly changing world. Lexicographers can collaborate with experts from around the globe, enriching their understanding of regional variations and slang.

Educational Requirements for Lexicographers:

Becoming a lexicographer

If you're considering to build a career path as linguistics graduates or in lexicography, it's important to equip yourself with the necessary knowledge and skills. Lexicography is a fascinating field that involves the creation and compilation of dictionaries, making it essential for lexicographers to have a solid educational background.

While there is no specific degree in lexicography, a strong foundation in linguistics, English language, or a related field is highly beneficial. Many lexicographers hold degrees in linguistics, philology, or language studies. These degree programs provide a comprehensive understanding of language and its intricacies, which is crucial for lexicographers.

Studying linguistics allows aspiring lexicographers to delve deep into the structure and usage of language. It provides them with the tools to analyze and interpret various linguistic phenomena, such as phonetics, morphology, syntax, and semantics. By gaining a profound understanding of language, lexicographers can effectively create and define words in dictionaries.

Essential Skills for Lexicographers

In addition to linguistic and language studies, lexicographers must possess a range of essential skills and knowledge to excel in their profession. These skills include:

* Strong research abilities: Research skills are crucial for lexicographers as they often need to consult various sources to gather information about words and their meanings. They must be adept at conducting thorough research to ensure the accuracy and reliability of their dictionary entries.
* Attention to detail: Attention to detail is another vital skill for lexicographers. They must meticulously analyze words, their definitions, and their usage examples to ensure precision and clarity. Lexicographers must pay close attention to nuances, subtle differences in meaning, and the appropriate contexts in which words are used.
* Ability to work independently and collaboratively: Lexicographers also need to possess the ability to work both independently and collaboratively. While they may spend a significant amount of time working alone, conducting research and compiling dictionary entries, they also need to collaborate with other language experts, editors, and proofreaders to ensure the accuracy and quality of their work.

Moreover, proficiency in corpus linguistics and digital tools is becoming increasingly important for lexicographers. Corpus linguistics involves the study of large collections of texts, which can provide valuable insights into word usage and frequency. Lexicographers need to be skilled in utilizing digital tools and software to analyze corpus data and extract relevant information for their dictionaries.

In conclusion, a career in lexicography requires a strong educational foundation in linguistics, English language, or a related field. Lexicographers must possess a deep understanding of language structure and usage, strong research skills, attention to detail, the ability to work independently and collaboratively, and proficiency in corpus linguistics and digital tools. By acquiring these skills and knowledge, aspiring lexicographers can embark on a fulfilling and rewarding career in the world of dictionaries.

The Lexicographer's Toolbox

A lexicographer relies on various tools and resources to carry out their work effectively, such as:

* Dictionaries and thesauri: These references provide a wealth of information that aids in the process of word analysis and definition. By studying different types of dictionaries, such as monolingual, bilingual, and specialized dictionaries, lexicographers gain valuable insights into the structure, meaning, and usage of words.
* Corpus linguistics: Corpus linguistics involves analyzing large collections of texts to identify patterns and trends in language usage. By utilizing corpus linguistics, lexicographers can accurately define words and capture their nuances. They can observe how words are used in different contexts and determine their frequency of occurrence.
* Etymology: Etymology is the study of the origin and history of words. By understanding the etymology of a word, lexicographers can trace its roots and uncover its evolution over time. This knowledge adds depth and context to the definitions provided in dictionaries.
* Linguistic databases and software programs: These tools assist in organizing and managing the vast amount of data that lexicographers work with. They provide efficient ways to search, cross-reference, and update word entries.

Furthermore, lexicographers often collaborate with other language experts, such as linguists and subject specialists, to ensure the accuracy and comprehensiveness of their work. This collaborative approach allows for a more thorough analysis of words and their meanings.

In conclusion, the lexicographer's toolbox is filled with a variety of tools and resources that enable them to carry out their work effectively. From dictionaries and thesauri to corpus linguistics and etymology, each tool plays a crucial role in the process of word analysis and definition. With the help of these tools and the expertise of their colleagues, lexicographers strive to provide accurate and comprehensive language resources for users around the world.

The Process of Lexicography:

Studying as a lexicographer

Lexicography is a meticulous and multi-step process that entails meticulous research, analysis, and writing. It is a fascinating field that delves deep into the intricacies of language and aims to capture the essence of words and their meanings.

Let's explore the various steps involved in the process of lexicography in more detail.

Word Collection and Analysis

Lexicographers continually update and expand word databases by monitoring language use in various sources, such as literature, media, and online platforms. They immerse themselves in the vast ocean of words, carefully observing how language evolves and adapts to the ever-changing world.

By meticulously analyzing the collected data, lexicographers identify new words, word senses, and changes in usage. They unravel the intricate tapestry of language, uncovering hidden gems and linguistic nuances that shape our communication.

Every word is like a puzzle piece, waiting to be discovered and understood. Lexicographers meticulously examine each word, its origins, and its various meanings. They explore the historical context, cultural connotations, and semantic relationships that give words their unique flavor.

Definition Writing and Editing

Defining words may seem straightforward, but lexicographers face the challenge of encapsulating the full meaning of a word in a concise and clear manner. They embark on a quest to distill the essence of a word, to capture its true essence and convey it to the reader.

While becoming an academic researcher or Lexicographers, you carefully craft definitions that not only provide a clear understanding of a word but also evoke a sense of its richness and depth. They strive to strike a delicate balance between precision and accessibility, ensuring that the definitions are accurate, comprehensive, and reflect the current usage of the word.

Editing plays a crucial role in the lexicographic process. Lexicographers meticulously review and refine their definitions, polishing them to perfection. They scrutinize each word choice, sentence structure, and example usage, striving for clarity and coherence.

Career Paths in Lexicography

Lexicographers have diverse career opportunities in both traditional and digital domains.

Lexicography, the art and science of compiling dictionaries, offers a wide range of exciting career paths for language enthusiasts. Whether you have a passion for traditional print publications or a knack for digital innovation, the field of lexicography has something for everyone.

Opportunities in Publishing Houses

Many lexicographers find work in publishing houses, where they contribute to the creation of dictionaries, language reference materials, and educational resources. These roles involve collaborating with editors, researchers, and other linguistic experts.

Working in a publishing house allows lexicographers to immerse themselves in the world of words. They meticulously research and analyze language usage, etymology, and semantic nuances to ensure the accuracy and relevance of the content they create. Lexicographers also work closely with editors to refine definitions, examples, and usage notes, ensuring that the final product meets the needs of the target audience.

Lexicographers in publishing houses often specialize in specific subject areas, such as medical, legal, technical terminology, and even becoming a press sub-editor. This specialization allows them to develop a deep understanding of the terminology used in these fields and create comprehensive dictionaries tailored to the needs of professionals and students.

The Digital World of Lexicography

With the rise of digital platforms and the internet, lexicographers can now contribute to online dictionaries, language-learning apps, and text analysis tools. These roles require expertise in data management and digital lexicography.

In the digital realm, lexicographers harness the power of technology to create dynamic and interactive language resources. They collaborate with software developers, user experience designers, and linguists to design user-friendly interfaces and develop innovative features. Lexicographers in the digital world also work closely with data scientists to analyze large volumes of linguistic data and extract valuable insights.

Lexicographers in digital lexicography play a crucial role in ensuring that online dictionaries and language-learning apps provide accurate and up-to-date information. They continuously update and expand the content to reflect the evolving nature of language, incorporating new words, idioms, and expressions that emerge in various contexts.

Challenges and Rewards of Lexicography

Embarking on a career in lexicography presents both challenges and rewards.

Lexicography, the art and science of compiling dictionaries, is a fascinating field that requires a deep understanding of language and its complexities. It is a profession that demands dedication, meticulousness, and a passion for words. Let's explore some of the challenges and rewards that come with being a lexicographer.

Navigating the Complexities of Language

Language is a living entity, constantly evolving and adapting to the needs and preferences of its speakers. Lexicographers must stay up to date with emerging words, slang, and changes in usage. This requires continuous learning and adapting to the ever-changing linguistic landscape.

Imagine being in the shoes of a lexicographer, delving into the depths of language to uncover new words and phrases that have emerged from the depths of popular culture. It's like embarking on a linguistic treasure hunt, where the reward is a comprehensive understanding of the ever-evolving lexicon.

Lexicographers must also grapple with the intricacies of regional dialects, jargon, and specialized terminology. They meticulously research and analyze these linguistic nuances to ensure that their dictionaries accurately reflect the diverse ways in which language is used.

The Satisfaction of Shaping Language Use

Lexicographers have the privilege of shaping language usage through their work. By providing accurate and comprehensive definitions, they contribute to effective communication and enable the understanding of different cultures and perspectives.

Think about it - every time you look up a word in a dictionary, you are relying on the expertise of lexicographers who have carefully curated and crafted the definitions. They play a crucial role in ensuring that words are understood in their proper context, preventing miscommunication and promoting clarity.

Lexicographers also have the opportunity to document the evolution of language. They observe how words change in meaning over time and capture these shifts in their dictionaries. This not only helps us understand the historical development of language but also provides valuable insights into the cultural and social changes that shape our world. Furthermore, lexicographers are often called upon to resolve disputes over language usage. They act as linguistic referees, providing authoritative guidance on matters of grammar, spelling, and pronunciation.

Tips for Aspiring Lexicographers

Are you considering a career in lexicography? Here are some tips to help you pave your way in this fascinating field.

Gaining Relevant Experience

Internships and volunteering opportunities with publishing houses, linguistic research institutions, or language technology companies can provide valuable hands-on experience and help you build connections within the industry.

Networking and Professional Development

Attend career events, workshops, and conferences related to lexicography and linguistics. Networking with professionals in the field can open doors to job opportunities and collaborations.

Bottom Line

Embarking on a career in lexicography requires dedication, passion, and a deep appreciation for language. By following this comprehensive guide, you'll be well on your way to becoming a skilled lexicographer and contributing to the world of words.

Details

Lexicography is the study of lexicons and the art of compiling dictionaries. It is divided into two separate academic disciplines:

* Practical lexicography is the art or craft of compiling, writing and editing dictionaries.
* Theoretical lexicography is the scholarly study of semantic, orthographic, syntagmatic and paradigmatic features of lexemes of the lexicon (vocabulary) of a language, developing theories of dictionary components and structures linking the data in dictionaries, the needs for information by users in specific types of situations, and how users may best access the data incorporated in printed and electronic dictionaries. This is sometimes referred to as "metalexicography".

There is some disagreement on the definition of lexicology, as distinct from lexicography. Some use "lexicology" as a synonym for theoretical lexicography; others use it to mean a branch of linguistics pertaining to the inventory of words in a particular language.

A person devoted to lexicography is called a lexicographer and is, according to a jest of Samuel Johnson, a "harmless drudge".

Focus

Generally, lexicography focuses on the design, compilation, use and evaluation of general dictionaries, i.e. dictionaries that provide a description of the language in general use. Such a dictionary is usually called a general dictionary or LGP dictionary (Language for General Purpose). Specialized lexicography focuses on the design, compilation, use and evaluation of specialized dictionaries, i.e. dictionaries that are devoted to a (relatively restricted) set of linguistic and factual elements of one or more specialist subject fields, e.g. legal lexicography. Such a dictionary is usually called a specialized dictionary or Language for specific purposes dictionary and following Nielsen 1994, specialized dictionaries are either multi-field, single-field or sub-field dictionaries.

It is now widely accepted that lexicography is a scholarly discipline in its own right and not a sub-branch of applied linguistics, as the chief object of study in lexicography is the dictionary.

Lexicography is the practice of creating books, computer programs, or databases that reflect lexicographical work and are intended for public use. These include dictionaries and thesauri which are widely accessible resources that present various aspects of lexicology, such as spelling, pronunciation, and meaning.

Lexicographers are tasked with defining simple words as well as figuring out how compound or complex words or words with many meanings can be clearly explained. They also make decisions regarding which words should be kept, added, or removed from a dictionary. They are responsible for arranging lexical material (usually alphabetically) to facilitate understanding and navigation.

Etymology

Coined in English 1680, the word "lexicography" derives from the Greek (lexikographos), "lexicographer", from λεξικόν (lexicon), neut. of lexikos, "of or for words", from (lexis), "speech", "word"[7] (in turn from (lego), "to say", "to speak") and (grapho), "to scratch, to inscribe, to write".

Aspects

Practical lexicographic work involves several activities, and the compilation of well-crafted dictionaries requires careful consideration of all or some of the following aspects:

* profiling the intended users (i.e. linguistic and non-linguistic competences) and identifying their needs
* defining the communicative and cognitive functions of the dictionary
* selecting and organizing the components of the dictionary
* choosing the appropriate structures for presenting the data in the dictionary (i.e. frame structure, distribution structure, macro-structure, micro-structure and cross-reference structure)
* selecting words and affixes for systematization as entries
* selecting collocations, phrases and examples
* choosing lemma forms for each word or part of word to be lemmatized
* defining words
* organizing definitions
* specifying pronunciations of words
* labeling definitions and pronunciations for register and dialect, where appropriate
* selecting equivalents in bi- and multi-lingual dictionaries
* translating collocations, phrases and examples in bi- and multilingual dictionaries
* designing the best way in which users can access the data in printed and electronic dictionaries

One important goal of lexicography is to keep the lexicographic information costs incurred by dictionary users as low as possible. Nielsen (2008) suggests relevant aspects for lexicographers to consider when making dictionaries as they all affect the users' impression and actual use of specific dictionaries.

Theoretical lexicography concerns the same aspects as lexicography, but aims to develop principles that can improve the quality of future dictionaries, for instance in terms of access to data and lexicographic information costs. Several perspectives or branches of such academic dictionary research have been distinguished: 'dictionary criticism' (or evaluating the quality of one or more dictionaries, e.g. by means of reviews (see Nielsen 1999), 'dictionary history' (or tracing the traditions of a type of dictionary or of lexicography in a particular country or language), 'dictionary typology' (or classifying the various genres of reference works, such as dictionary versus encyclopedia, monolingual versus bilingual dictionary, general versus technical or pedagogical dictionary), 'dictionary structure' (or formatting the various ways in which the information is presented in a dictionary), 'dictionary use' (or observing the reference acts and skills of dictionary users), and 'dictionary IT' (or applying computer aids to the process of dictionary compilation).

One important consideration is the status of 'bilingual lexicography', or the compilation and use of the bilingual dictionary in all its aspects (see e.g. Nielsen 1994). In spite of a relatively long history of this type of dictionary, it is often said to be less developed in a number of respects than its unilingual counterpart, especially in cases where one of the languages involved is not a major language. Not all genres of reference works are available in interlingual versions, e.g. LSP, learners' and encyclopedic types, although sometimes these challenges produce new subtypes, e.g. 'semi-bilingual' or 'bilingualised' dictionaries such as Hornby's (Oxford) Advanced Learner's Dictionary English-Chinese, which have been developed by translating existing monolingual dictionaries.

Additional Information

Lexicography is the compiling, editing, or writing of a dictionary. It is distinct from lexicology, the study of the words in a given language, including their origins, evolution, meanings, usage, and contexts.

History of lexicography

The history of lexicographical practices can be traced back to about 3200 bce, when Sumerians began compiling word lists in cuneiform writing on clay tablets to teach literacy. The history of English lexicography dates back to the expansion of Latin Christianity into England (beginning at the end of the 6th century ce), when English-speaking priests and monks needed to learn Latin to read the Bible and conduct services in the liturgical language. In 1218 John of Garland, an English-born Parisian teacher, coined the word dictionarius (Latin: “of or pertaining to words”) as a title for an elementary Latin textbook. The first examples of modern, comprehensive English dictionaries came in the 18th century. A Dictionary of the English Language, Samuel Johnson’s seminal work in precision of definition and organization, was published in 1755. It included quotations and prescriptive commentaries about word usage.

Practical and theoretical lexicography

Lexicography is divided into two fields: practical and theoretical. Practical lexicography is concerned with compiling, writing, and editing dictionaries. Practical lexicographers focus on creating user-friendly dictionaries with accurate, up-to-date, and comprehensive information. Theoretical lexicography, also called metalexicography, is concerned with dictionary research. Theoretical lexicographers focus on researching structural and semantic relationships among words in current dictionaries to improve information organization and structure in future dictionaries. They often focus their research on specific types of dictionaries or elements of a dictionary’s compilation.

Types of dictionaries

The different types of dictionaries are vast and varied. In addition to what are considered “general purpose” dictionaries and language learners’, or bilingual, dictionaries, there are specialized dictionaries, including etymological, pronunciation, and usage dictionaries. Some dictionaries focus on the vocabulary of specific fields of knowledge—e.g., biology, psychology, law, medicine, religion, literature, economics, and fine arts.

Practical lexicographical processes

Lexicographers continually track language by reading books, newspapers, industry-specific journals, online corpora, social media, and any text in which they might discover a new word or a new use for an already recorded word. When lexicographers encounter a new word or usage, they create a citation in a searchable database, noting the word’s context and source. Then they search other databases of words from numerous different sources, including everything from articles to popular literature to song lyrics to speeches. Using these databases, they determine if a word meets certain criteria for inclusion in a dictionary—such as frequent, widespread, and meaningful use. If a word meets the criteria, lexicographers draft a definition for the word and forward it to a series of editors for review. Once the word and definition are approved, they are entered into the system, reviewed by a copy editor, proofread, and added to a dictionary.

Lexicography in the digital age

The shift to digital dictionaries has added a new dimension to the way lexicographers write definitions and structure digital dictionary entries. Web analytics allow lexicographers to see which words users look up more frequently, and the lexicographers can spend more time revising the definitions of those words. Because digital dictionaries are interactive, when lexicographers write definitions, they consider where to place explanatory hyperlinks and how to structure entries for online presentation, sometimes breaking up paragraphs into individual lines.

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Jai Ganesh · 2025-03-04 00:00:41

2378) River Congo

Gist

The mighty Congo is Africa’s second-longest river after the Nile; in terms of flow, it’s second only to the Amazon. With a basin spanning most of the Democratic Republic of Congo (DRC) and parts of six neighboring countries, the river has been a vital lifeline for centuries, forming (with its tributaries) a vast inland waterway that allows access to places still inaccessible by road.

The river also nourishes immense biodiversity: It’s home to at least 700 fish species, and it supports the world’s second-largest rainforest. It also empties water and sediment into one of the largest carbon sinks in the world, the Congo Plume in the Atlantic.

The Congo is the deepest river in the world. Its headwaters are in the north-east of Zambia, between Lake Tanganyika and Lake Nyasa (Malawi), 1760 metres above sea level; it flows into the Atlantic Ocean.

Summary:

Introduction

The Congo River flows through the heart of Africa for about 2,900 miles (4,700 kilometers). It is the second longest river in Africa, after the Nile.

The Congo Basin is the area of land that is drained by the river. The basin includes all of the Democratic Republic of the Congo. It also covers parts of the Republic of the Congo, the Central African Republic, Zambia, Angola, Cameroon, and Tanzania.

Geography

The farthest source of the Congo is a river in the highlands of northeastern Zambia. But the Congo’s main stream begins in the southeastern part of the Democratic Republic of the Congo. From there, the river makes a giant arc across central Africa. It flows to the northwest, west, and southwest before reaching the west coast. It empties into the Atlantic Ocean at the town of Banana, in the Democratic Republic of the Congo.

It is impossible to travel the entire length of the river by boat. Several waterfalls block the western end of the river’s course. Therefore, river travel begins and ends farther upstream, at the city of Kinshasa.

Plants and Animals

The Congo River basin contains the second largest tropical rainforest. Only the Amazon rainforest is larger. Savannas, or tropical grasslands, border the Congo rainforest.

Many types of birds live near the river, and many types of fish live in it. Crocodiles, water snakes, turtles, and hippopotamuses also swim in the Congo’s waters.

Economy

Fishing in the Congo River is an important activity. The river also is a source of electric power, produced by dams. In addition, the Congo River and its tributaries form a large transportation network. Many port cities and towns are located along the banks. The capital cities of Kinshasa and Brazzaville sit on opposite sides of a wide part of the river, called Malebo Pool.

Details

The Congo River, formerly also known as the Zaire River, is the second-longest river in Africa, shorter only than the Nile, as well as the third-largest river in the world by discharge volume, following the Amazon and Ganges rivers. It is the world's deepest recorded river, with measured depths of around 220 m (720 ft). The Congo–Lualaba–Luvua–Luapula–Chambeshi River system has an overall length of 4,700 km (2,900 mi), which makes it the world's ninth-longest river. The Chambeshi is a tributary of the Lualaba River, and Lualaba is the name of the Congo River upstream of Boyoma Falls, extending for 1,800 km (1,100 mi).

Measured along with the Lualaba, the main tributary, the Congo River has a total length of 4,370 km (2,720 mi). It is the only major river to cross the equator twice. The Congo Basin has a total area of about 4,000,000 {km}^{2} (1,500,000 sq mi), or 13% of the entire African landmass.

Name

The name Congo/Kongo originates from the Kingdom of Kongo once located on the southern bank of the river. The kingdom in turn was named after the indigenous Bantu Kongo people, known in the 17th century as "Esikongo". South of the Kingdom of Kongo proper lay the similarly named Kakongo kingdom, mentioned in 1535. Abraham Ortelius labelled "Manicongo" as the city at the mouth of the river in his world map of 1564. The tribal names in Kongo possibly derive from a word for a public gathering or tribal assembly. The modern name of the Kongo people or Bakongo was introduced in the early 20th century.

The name Zaire is from a Portuguese adaptation of a Kikongo word, nzere ("river"), a truncation of nzadi o nzere ("river swallowing rivers"). The river was known as Zaire during the 16th and 17th centuries; Congo seems to have replaced Zaire gradually in English usage during the 18th century, and Congo is the preferred English name in 19th-century literature, although references to Zahir or Zaire as the name used by the inhabitants remained common. The Democratic Republic of the Congo and the Republic of the Congo are named after it, as was the previous Republic of the Congo which had gained independence in 1960 from the Belgian Congo. The Republic of Zaire during 1971–1997 was also named after the river's name in French and Portuguese.

The Congo's drainage basin covers 4,014,500 {km}^{2} (1,550,000 sq mi), an area nearly equal to that of the European Union. The Congo's discharge at its mouth ranges from 23,000 to 75,000 {m}^{3}/s (810,000 to 2,650,000 cu ft/s), with an average of 41,000 {m}^{3}/s (1,400,000 cu ft/s). The river transports annually 86 million tonnes of suspended sediment to the Atlantic Ocean and an additional 6% of bedload.

The river and its tributaries flow through the Congo rainforest, the second largest rainforest area in the world, after the Amazon rainforest in South America. The river also has the second-largest flow in the world, behind the Amazon; the second-largest drainage basin of any river, behind the Amazon; and is one of the deepest rivers in the world, at depths greater than 220 m (720 ft). Because its drainage basin includes areas both north and south of the Equator, its flow is stable, as there is always at least one part of the river experiencing a rainy season.

The sources of the Congo are in the highlands and mountains of the East African Rift, as well as Lake Tanganyika and Lake Mweru, which feed the Lualaba River, which then becomes the Congo below Boyoma Falls. The Chambeshi River in Zambia is generally taken as the source of the Congo in line with the accepted practice worldwide of using the longest tributary, as with the Nile River.

The Congo flows generally toward the northwest from Kisangani just below the Boyoma Falls, then gradually bends southwestward, passing by Mbandaka, joining with the Ubangi River and running into the Pool Malebo (Stanley Pool). Kinshasa (formerly Léopoldville) and Brazzaville are on opposite sides of the river at the Pool, where the river narrows and falls through a number of cataracts in deep canyons (collectively known as the Livingstone Falls), running by Matadi and Boma, and into the sea at Muanda.

Lower Congo constitutes the "lower" parts of the great river; that is the section of the river from the river mouth at the Atlantic coast to the twin capitals of Brazzaville and Kinshasa. In this section of the river, there are two significant tributaries, both on the left or south side. The Kwilu River originates in the hills near the Angolan border and enters the Congo some 100 km upstream from Matadi. The other is the Inkisi River, that flows in a northerly direction from the Uíge Province in Angola to the confluence with the Congo at Zongo some 80 km (50 mi) downstream from the twin capitals. Because of the vast number of rapids, in particular the Livingstone Falls, this section of the river is not operated continuously by riverboats.

Additional Information - I

Congo River is a river in west-central Africa. With a length of 2,900 miles (4,700 km), it is the continent’s second longest river, after the Nile. It rises in the highlands of northeastern Zambia between Lakes Tanganyika and Nyasa (Malawi) as the Chambeshi River at an elevation of 5,760 feet (1,760 metres) above sea level and at a distance of about 430 miles (700 km) from the Indian Ocean. Its course then takes the form of a giant counterclockwise arc, flowing to the northwest, west, and southwest before draining into the Atlantic Ocean at Banana (Banane) in the Democratic Republic of the Congo. Its drainage basin, covering an area of 1,335,000 square miles (3,457,000 square km), takes in almost the entire territory of that country, as well as most of the Republic of the Congo, the Central African Republic, eastern Zambia, and northern Angola and parts of Cameroon and Tanzania.

With its many tributaries, the Congo forms the continent’s largest network of navigable waterways. Navigability, however, is limited by an insurmountable obstacle: a series of 32 cataracts over the river’s lower course, including the famous Inga Falls. These cataracts render the Congo unnavigable between the seaport of Matadi, at the head of the Congo estuary, and Malebo Pool, a lakelike expansion of the river. It was on opposite banks of Malebo Pool—which represents the point of departure of inland navigation—that the capitals of the former states of the French Congo and the Belgian Congo were founded: on the left bank Kinshasa (formerly Léopoldville), now the capital of the Democratic Republic of the Congo, and on the right bank Brazzaville, now the capital of the Republic of the Congo.

The Amazon and the Congo are the two great rivers of the world that flow out of equatorial zones where heavy rainfall occurs throughout all or almost all of the year. Upstream from Malebo Pool, the Congo basin receives an average of about 60 inches (1,500 mm) of rain a year, of which more than one-fourth is discharged into the Atlantic. The drainage basin of the Congo is, however, only about half the size of that of the Amazon, and the Congo’s rate of flow—1,450,000 cubic feet (41,000 cubic metres) per second at its mouth—is considerably less than the Amazon’s flow of more than 6,180,000 cubic feet (175,000 cubic metres) per second.

While the Chambeshi River, as the remotest source, may form the Congo’s original main stream in terms of the river’s length, it is another tributary—the Lualaba, which rises near Musofi in southeastern Democratic Republic of the Congo—that carries the greatest quantity of water and thus may be considered as forming the Congo’s original main stream in terms of water volume.

When the river first became known to Europeans at the end of the 15th century, they called it the Zaire, a corruption of a word that is variously given as nzari, nzali, njali, nzaddi, and niadi and that simply means “river” in local African languages. It was only in the early years of the 18th century that the river was first called the “Rio Congo,” a name taken from the kingdom of Kongo that had been situated along the lower course of the river. During the period (1971–97) when the Democratic Republic of the Congo was called Zaire, the government also renamed the river the Zaire. Even during that time, however, the river continued to be known throughout the world as the Congo. To the literary-minded the river is evocative of the famous 1902 short story “Heart of Darkness” by Joseph Conrad. His book conjured up an atmosphere of foreboding, treachery, greed, and exploitation. Today, however, the Congo appears as the key to the economic development of the central African interior.

Additional Information - II

The Congo River (also known as Zaire River) is the largest river in Africa. Its overall length of 4,700 km (2,922 miles) makes it the second longest in Africa (after the Nile). The river and its tributaries flow through the second largest rain forest area in the world, second only to the Amazon Rainforest in South America.

The river also has the second-largest flow in the world, behind the Amazon, and the second-largest watershed of any river, again trailing the Amazon. Its watershed is a little larger than that of the Mississippi River. Because large parts of the river basin sit north and south of the equator, its flow is steady, as there is always at least one river having a rainy season. The Congo gets its name from the old Kingdom of Kongo which was at the mouth of the river. The Democratic Republic of the Congo and the Republic of the Congo, both countries sitting along the river's banks, are named after it. From 1971 to 1997, the Democratic Republic of the Congo was called Zaire and its government called the river the Zaire River.

The sources of the Congo are in the Highlands and mountains of the East African Rift, as well as Lake Tanganyika and Lake Mweru, which feed the Lualaba River. This then becomes the Congo below Boyoma Falls. The Chambeshi River in Zambia is usually taken as the source of the Congo because of the accepted practice worldwide of using the longest tributary, as with the Nile River.

The Congo flows mostly west from Kisangani just below the falls, then slowly bends southwest, passing by Mbandaka, joining with the Ubangi River, and running into the Pool Malebo (Stanley Pool). Kinshasa (formerly Léopoldville) and Brazzaville are on opposite sides of the river at the Pool, where the river narrows and falls through a few cataracts in deep canyons (collectively known as the Livingstone Falls), running by Matadi and Boma, and into the sea at the small town of Muanda.

History of exploration

The mouth of the Congo was visited by Europeans in 1482, by the Portuguese Diogo Cão, and in 1817, by a British exploration under James Kingston Tuckey that went up the river as far as Isangila. Henry Morton Stanley was the first European to travel along the whole river.

Economic importance

Although the Livingstone Falls stop ships coming in from the sea, almost all of the Congo is navigable in parts, especially between Kinshasa and Kisangani. Railways cross the three major falls that interrupt navigation, and much of the trade of central Africa passes along the river. Goods include copper, palm oil, sugar, coffee, and cotton. The river can also be valuable for hydroelectric power, and Inga Dams below Pool Malebo have been built.

In February of 2005, South Africa's state owned power company, Eskom, said that they had a proposal to increase the amount of electric power that the Inga can make through improvements and the building of a new hydroelectric dam. The project would bring the highest output of the dam to 40 GW, twice that of China's Three Gorges Dam.

Geological history

In the Mesozoic period before the continental drift opened the South Atlantic Ocean, the Congo was the upper part of a river about 12,000 km (7,500 miles) long that flowed west across the parts of Gondwanaland, now called Africa and South America.

Jai Ganesh · 2025-03-05 00:02:22

2379) River Zambezi

Gist

The Zambezi (meaning “Great River” in the language of the Tonga people) includes along its course the Victoria Falls, one of the world's greatest natural wonders, and the Kariba and Cahora Bassa dams, two of Africa's largest hydroelectric projects.

The 2,574 km (1,599 mi) river rises in Zambia and flows through eastern Angola, along the north-eastern border of Namibia and the northern border of Botswana, then along the border between Zambia and Zimbabwe to Mozambique, where it crosses the country to empty into the Indian Ocean.

Summary

Zambezi River, river draining a large portion of south-central Africa. Together with its tributaries, it forms the fourth largest river basin of the continent. The river flows eastward for about 2,200 miles (3,540 kilometres) from its source on the Central African Plateau to empty into the Indian Ocean. With its tributaries, it drains an area of more than 500,000 square miles (1,300,000 square kilometres). The Zambezi (meaning “Great River” in the language of the Tonga people) includes along its course the Victoria Falls, one of the world’s greatest natural wonders, and the Kariba and Cahora Bassa dams, two of Africa’s largest hydroelectric projects. The river either crosses or forms the boundaries of six countries—Angola, Zambia, Namibia, Botswana, Zimbabwe, and Mozambique—and the use of its waters has been the subject of a series of international agreements.

Physical features:

Physiography

The Zambezi rises out of a marshy bog near Kalene Hill, Zambia, about 4,800 feet (1,460 metres) above sea level, and flows some 20 miles before entering Angola, through which it runs for more than 175 miles. In this first section of its course, the river is met by more than a dozen tributaries of varying sizes. Shortly after reentering Zambia, the river flows over the Chavuma Falls and enters a broad region of hummocky, sand-covered floodplains, the largest of which is the Barotse, or Zambezi, Plain. The region is inundated during the summer floods, when it receives fertile alluvial soils. The main tributaries intersecting the river along the plains are the Kabompo River from the east and the larger Lungué-Bungo (Lungwebungo) River from the west.

The Zambezi then enters a stretch of rapids that extends from Ngonye (Sioma) Falls south to the Katima Mulilo Rapids, after which for about 80 miles it forms the border between Zambia to the north and the eastern Caprivi Strip—an extension of Namibia—to the south. In this stretch the river meanders through the broad grasslands of the Sesheke Plain until it is joined by the Cuando (Kwando) River. Near Kazungula, Zambia, the river, after flowing past Botswana territory to the south, turns almost due east and forms the frontier between Zambia and Zimbabwe. From the Cuando confluence to the Victoria Falls, the Zambezi varies considerably in width, from open reaches with sand islands to stretches of rapids through narrow channels separated by numerous rock islands.

The Victoria Falls mark the end of the upper course of the Zambezi, as its waters tumble with a thunderous roar and an enormous cloud of spray. The area around the falls was once covered by a thick layer of lava, which as it cooled formed wide cracks, or joints, that became filled with softer sediments. As the Zambezi cut its present valley it encountered one of these joints, eroded the sediment, and created a trench, eventually forcing a gap at the lower end of the trench that quickly widened into a gorge. The force of the water also created a second gap at the upper end of the trench that gradually diverted the river until the trench itself was left dry. As the river cut backward it repeated the process, scouring eight successive waterfalls in the past half million years.

The Zambezi’s middle course extends about 600 miles from Victoria Falls to the eastern end of Lake Cahora Bassa in Mozambique. It continues to form the boundary between Zambia and Zimbabwe until it crosses the Mozambique border at Luangwa. Below the falls a gorge some 60 miles long has been formed by the trench-scouring process, through which the river descends in a series of rapids. Just upstream of Lake Kariba the river valley widens and is contained by escarpments nearly 2,000 feet high. The middle Zambezi is notable for the two man-made lakes, Kariba and Cahora Bassa, that constitute much of this stretch of the river. Between the two lakes the Zambezi trends northeast for nearly 40 miles before it turns east below the confluence with the Kafue River, the Zambezi’s largest tributary. In this section the river rushes through two rocky, narrow gorges, the first just below the Kariba Dam and the other above the confluence with the Luangwa River.

At the dam at the eastern end of Lake Cahora Bassa, the Zambezi begins its lower course, during which it descends from the Central African Plateau to the coastal plain. At first the hilly country is replaced by flat areas at the head of the Tete Basin, and the river becomes more placid. About 40 miles downstream the river has cut the Lupata Gorge through a range of hills, where it emerges onto the Mozambique Plain and occupies a broad valley that spreads out in places to a width of three to five miles. Near Vila Fontes the river receives its last great tributary, the Shire River, which drains Lake Nyasa (Malaŵi) some 210 miles to the north.

At its mouth the Zambezi splits into a wide, flat, and marshy delta obstructed by sandbars. There are two main channels, each again divided into two. The wider, eastern channel splits into the Muselo River to the north and the main mouth of the Zambezi to the south. The western channel forms both the Inhamissengo River and the smaller Melambe River. North of the main delta the Chinde River separates from the Zambezi’s main stream to form a navigable channel leading to a shallow harbour.

Hydrology

The Zambezi, according to measurements taken at Maramba (formerly Livingstone), Zambia, experiences its maximum flow in March or April. In October or November the discharge diminishes to less than 10 percent of the maximum. The annual average flow reaches about 247,000 cubic feet (7,000 cubic metres) per second. Measurements taken at Kariba Dam reflect the same seasonal pattern; the highest flood recorded there was in March 1958, when the flow reached 565,000 cubic feet per second.

Climate of the Zambezi River

The Zambezi River lies within the tropics. The upper and middle course of the river is on an upland plateau, and temperatures, modified by altitude, are relatively mild, generally between 64° and 86° F (18° and 30° C). The winter months (May to July) are cool and dry, with temperatures averaging 68° F (20° C). Between August and October there is a considerable rise in average temperatures, particularly in the river valley itself; just before the rains begin in October temperatures there become excessively hot, often reaching 104° F (40° C). The rainy season lasts from November to April. Rain falls in short, intense thundershowers—the rate sometimes reaching 6 inches (150 millimetres) per hour—with skies clearing between downpours. In these months the upper Zambezi receives nearly all its total rainfall, and this accounts for the great variation in the flow of the river throughout the year. In all, the upper and middle Zambezi valley receives 22 to 30 inches of rain per year. Studies have suggested that a microclimate in the area of Lake Kariba has created a rise in precipitation, possibly as a result of a lake breeze blocked by the escarpment that produces thunderstorms.

In the lower course of the river in Mozambique the influence of the summer monsoon increases the levels of precipitation and humidity. Temperatures are also higher—determined more by the latitude and less by altitude—as the river descends from the plateau.

Plant life

The vegetation along the upper and middle course of the Zambezi is predominantly savanna, with deciduous trees, grass, and open woodland. Mopane woodland (Colophospermum mopane) is predominant on the alluvial flats of the low-lying river valleys and is highly susceptible to fire. Grass, when present, is typically short and sparse. Forestland with species of the genus Baikiaea, found extensively on sandy interfluves between drainage channels, is economically the most important vegetation type in Zambia, for it is the source of the valuable Rhodesian teak (Baikiaea plurijuga). Destruction of the Baikiaea forest results in a regression from forest to grassland, a slow process involving intermediate stages of scrub vegetation. The river additionally has a distinct fringing vegetation, mainly riverine forest including ebony (Diospyros mespiliformis) and small shrubs and ferns (e.g., Haemanthus). In the lower course of the Zambezi, dense bush and evergreen forest, with palm trees and patches of mangrove swamp, is the typical vegetation.

Animal life

The tiger fish is one of the few species found both above and below the Victoria Falls. Pike is predominant in the upper course of the river, as are yellowfish and barbel. Bream are now common both above and below the falls. Crocodiles abound in the Zambezi, though they generally avoid stretches of fast-running water. Hippopotamuses are also found in the upper and lower stretches of the Zambezi.

Elephants are common over much of the river’s course, particularly in areas such as the Sesheke Plain and near the Luangwa confluence. Game animals include buffalo, eland, sable, roan, kudu, waterbuck, impala, duiker, bushbuck, reedbuck, bushpig, and warthog. Of the big cats, lions can be found in the Victoria Falls National Park in Zimbabwe and elsewhere along the river’s course; cheetahs, although comparatively rare, can be sighted; and leopards, rarely seen by daylight, are common, both in the plains and the river gorges. Baboons and monkeys abound throughout the region.

The people

The Lozi (Barotse), who dominate much of the upper Zambezi, have taken advantage of the seasonal flooding of the Barotse Plain for centuries and have an agricultural economy that is supplemented by animal husbandry, fishing, and trade. The main groups of the middle Zambezi include the Tonga, Shona, Chewa, and Nsenga peoples, all of whom largely practice subsistence agriculture. In Mozambique the riverine population is varied; many engage in commercial agriculture—the growing of sugarcane and cotton in particular—which was established by the Portuguese.

The economy:

Navigation

Given its numerous natural barriers—sandbars at the mouth, shallowness, and rapids and cataracts—the Zambezi is of little economic significance as a trade route. About 1,620 miles of the river, however, are navigable by shallow-draft steamers. The longest stretch of unbroken water runs from the river delta about 400 miles upstream to the Cahora Bassa Dam. Above the dam Lake Cahora Bassa is navigable to its confluence with the Luangwa River, where navigation is interrupted again to the Kariba Dam. Lake Kariba is navigable, but the river again becomes impassable from the end of the lake to the Ngonye Falls, some 250 miles upstream. It is again navigable by shallow-draft boats for the 300 miles between the Ngonye and Chavuma falls and then for another 120 miles above Chavuma.

The river has four major crossing points. The Victoria Falls Bridge, the first from the head of the river, carries rail, road, and foot traffic between Zambia and Zimbabwe. The dam wall at Kariba is heavily used by road traffic, and a road bridge at Chirundu, Zimb., also connects the two countries. The fourth major crossing is the rail and road bridge between Mutarara (Dona Ana) and Vila de Sena, Mozambique. There are also a number of motor ferries crossing the river at various points.

Kariba and Cahora Bassa schemes

The Kariba Dam harnesses the Zambezi at Kariba, Zimb., 300 miles below Victoria Falls. A concrete-arch dam with a maximum height of 420 feet and a crest length of 1,900 feet carries a road connecting the Zambian and Zimbabwean banks of the gorge. Six floodgates permit a discharge of some 335,000 cubic feet of water per second. Both Zambia and Zimbabwe obtain most of their electricity from the Kariba Dam. Lake Kariba covers an area of about 2,000 square miles. The flooded land was previously inhabited by about 51,000 Tonga agriculturalists, who had to be resettled. The lake stretches for 175 miles from the dam to Devil’s Gorge and is 20 miles across at its widest point. Three townships have been built around lakeshore harbours at Kariba and at Siavonga and Sinazongwe, Zambia. Tourist resorts have also been developed along the lakeshore.

Lake Cahora Bassa was formed by a dam across the Zambezi at the head of Cahora Bassa Gorge, about 80 miles northwest of Tete, Mozambique. The dam, 560 feet high and 1,050 feet wide at its crest, impounds the river for 150 miles to the Mozambique–Zambia border, providing hydroelectric power and water for crop irrigation.

Study and exploration

The first non-Africans to reach the Zambezi were Arab traders, who utilized the river’s lower reaches from the 10th century onward. They were followed in the 16th century by the Portuguese, who hoped to use the river to develop a trade in ivory, gold, and slaves. Until the 19th century, the river, then called the Zanbere, was believed to flow south from a vast inland sea that was also thought to be the origin of the Nile River. Accurate mapping of the Zambezi did not take place until the Scottish missionary and explorer David Livingstone charted most of the river’s course in the 1850s. Searching for a trade route to the East African coast, he traveled from Sesheke, 150 miles above Victoria Falls, to the Indian Ocean. His map of the river remained the most accurate until the 20th century, when further surveys finally traced the Zambezi to its source.

Details

The Zambezi (also spelled Zambeze and Zambesi) is the fourth-longest river in Africa, the longest east-flowing river in Africa and the largest flowing into the Indian Ocean from Africa. Its drainage basin covers 1,390,000 {km}^{2} (540,000 sq mi), slightly less than half of the Nile's. The 2,574 km (1,599 mi) river rises in Zambia and flows through eastern Angola, along the north-eastern border of Namibia and the northern border of Botswana, then along the border between Zambia and Zimbabwe to Mozambique, where it crosses the country to empty into the Indian Ocean.

The Zambezi's most noted feature is Victoria Falls. Its other falls include the Chavuma Falls at the border between Zambia and Angola and Ngonye Falls near Sioma in western Zambia.

The two main sources of hydroelectric power on the river are the Kariba Dam, which provides power to Zambia and Zimbabwe, and the Cahora Bassa Dam in Mozambique, which provides power to Mozambique and South Africa. Additionally, two smaller power stations are along the Zambezi River in Zambia, one at Victoria Falls and the other in Zengamina, near Kalene Hill in the Ikelenge District.

Course:

Origins

The river rises in a black, marshy dambo in dense, undulating miombo woodland 50 km (31 mi) north of Mwinilunga and 20 km (12 mi) south of Ikelenge in the Ikelenge District of North-Western Province, Zambia, at about 1,524 metres (5,000 ft) above sea level. The area around the source is a national monument, forest reserve, and important bird area.

Eastward of the source, the watershed between the Congo and Zambezi Basins is a well-marked belt of high ground, running nearly east–west and falling abruptly to the north and south. This distinctly cuts off the basin of the Lualaba (the main branch of the upper Congo) from the Zambezi. In the neighborhood of the source, the watershed is not as clearly defined, but the two river systems do not connect.

The region drained by the Zambezi is a vast, broken-edged plateau 900–1,200 m high, composed in the remote interior of metamorphic beds and fringed with the igneous rocks of the Victoria Falls. At Chupanga, on the lower Zambezi, thin strata of grey and yellow sandstones, with an occasional band of limestone, crop out on the bed of the river in the dry season, and these persist beyond Tete, where they are associated with extensive seams of coal. Coal is also found in the district just below Victoria Falls. Gold-bearing rocks occur in several places.

Upper Zambezi

The river flows to the southwest into Angola for about 240 km (150 mi), then is joined by sizeable tributaries such as the Luena and the Chifumage flowing from highlands to the north-west. It turns south and develops a floodplain, with extreme width variation between the dry and rainy seasons. It enters dense evergreen Cryptosepalum dry forest, though on its western side, Western Zambezian grasslands also occur. Where it re-enters Zambia, it is nearly 400 m (1,300 ft) wide in the rainy season and flows rapidly, with rapids ending in the Chavuma Falls, where the river flows through a rocky fissure. The river drops about 400 m (1,300 ft) in elevation from its source at 1,500 m (4,900 ft) to the Chavuma Falls at 1,100 m (3,600 ft), over a distance of about 400 km (250 mi). From this point to the Victoria Falls, the level of the basin is very uniform, dropping only by another 180 m (590 ft) across a distance of around 800 km (500 mi).

The first of its large tributaries to enter the Zambezi is the Kabompo River in the North-Western Province of Zambia. The savanna through which the river flows gives way to a wide floodplain, studded with Borassus fan palms. A little farther south is the confluence with the Lungwebungu River. This is the beginning of the Barotse Floodplain, the most notable feature of the upper Zambezi, but this northern part does not flood so much and includes islands of higher land in the middle.

About 30 km below the confluence of the Lungwebungu, the country becomes very flat, and the typical Barotse Floodplain landscape unfolds, with the flood reaching a width of 25 km in the rainy season. For more than 200 km downstream, the annual flood cycle dominates the natural environment and human life, society, and culture. About 80 km further down, the Luanginga, which with its tributaries drains a large area to the west, joins the Zambezi. A short distance higher up on the east, the main stream is joined in the rainy season by overflow of the Luampa/Luena system.

A short distance downstream of the confluence with the Luanginga is Lealui, one of the capitals of the Lozi people, who populate the Zambian region of Barotseland in the Western Province. The chief of the Lozi maintains one of his two compounds at Lealui; the other is at Limulunga, which is on high ground and serves as the capital during the rainy season. The annual move from Lealui to Limulunga is a major event, celebrated as one of Zambia's best-known festivals, the Kuomboka.

After Lealui, the river turns south-southeast. From the east, it continues to receive numerous small streams, but on the west, it is without major tributaries for 240 km. Before this, the Ngonye Falls and subsequent rapids interrupt navigation. South of Ngonye Falls, the river briefly borders Namibia's Caprivi Strip. Below the junction of the Cuando River and the Zambezi, the river bends almost due east. Here, the river is broad and shallow and flows slowly, but as it flows eastward towards the border of the great central plateau of Africa, it reaches a chasm into which the Victoria Falls plunge.

Middle Zambezi

The Victoria Falls are considered the boundary between the upper and middle Zambezi. Below them, the river continues to flow due east for about 200 km (120 mi), cutting through perpendicular walls of basalt 20 to 60 m (66 to 197 ft) apart in hills 200 to 250 m (660 to 820 ft) high. The river flows swiftly through the Batoka Gorge, the current being continually interrupted by reefs. It has been described[18][citation needed] as one of the world's most spectacular whitewater trips, a tremendous challenge for kayakers and rafters alike. Beyond the gorge are a succession of rapids that end 240 km (150 mi) below Victoria Falls. Over this distance, the river drops 250 m (820 ft).

At this point, the river enters Lake Kariba, created in 1959 following the completion of the Kariba Dam. The lake is one of the largest man-made lakes in the world, and the hydroelectric power-generating facilities at the dam provide electricity to much of Zambia and Zimbabwe.

The Luangwa and Kafue rivers are the two largest left-hand tributaries of the Zambezi. The Kafue joins the main river in a quiet, deep stream about 180 m (590 ft) wide. From this point, the northward bend of the Zambezi is checked, and the stream continues due east. At the confluence of the Luangwa (15°37' S), it enters Mozambique.

The middle Zambezi ends where the river enters Lake Cahora Bassa, formerly the site of dangerous rapids known as Kebrabassa; the lake was created in 1974 by the construction of the Cahora Bassa Dam.

Lower Zambezi

The lower Zambezi's 650 kilometres (400 mi) from Cahora Bassa to the Indian Ocean is navigable, although the river is shallow in many places during the dry season. This shallowness arises as the river enters a broad valley and spreads out over a large area. Only at one point, the Lupata Gorge, 320 kilometres (200 mi) from its mouth, is the river confined between high hills. Here, it is scarcely 200 metres (660 ft) wide. Elsewhere it is from 5 to 8 kilometres (3 to 5 mi) wide, flowing gently in many streams. The river bed is sandy, and the banks are low and reed-fringed. At places, however, and especially in the rainy season, the streams unite into one broad, fast-flowing river.

About 160 kilometres (99 mi) from the sea, the Zambezi receives the drainage of Lake Malawi through the Shire River. On approaching the Indian Ocean, the river splits up into a delta. Each of the primary distributaries, Kongone, Luabo, and Timbwe, is obstructed by a sand bar. A more northerly branch, called the Chinde mouth, has a minimum depth at low water of 2 metres (6 ft 7 in) at the entrance and 4 metres (13 ft) further in, and is the branch used for navigation. About 100 kilometres (62 mi) further north is a river called the Quelimane, after the town at its mouth. This stream, which is silting up, receives the overflow of the Zambezi in the rainy season.

Additional Information

The Zambezi is the fourth longest river in Africa, after the Nile, Congo, and Niger Rivers. It is the longest east flowing river in Africa.

It flows through six countries on its journey from its source in north-western Zambia to the Indian Ocean, an amazing 2 700 km.

This river evokes mystery and excitement with few rivers in the world remaining as pristine or as little explored.

The source of the mighty Zambezi River lies at about 1 500 m (4 900ft) above sea level in the Mwinilunga District, very close to the border where Zambia, Angola and the Congo meet.

From there it flows through Zambia, Angola, Namibia and Botswana then back along the border of Zambia and Zimbabwe finally discharging into the Indian Ocean at its delta in Mozambique. The area of its catchment basin is 1 390 000 square km which is half that of the Nile.

The Power of the Zambezi River has been harnessed along its journey at two points, the first being Kariba Dam in Zimbabwe and the second Cahora Bassa Dam in Mozambique. Both these dams are sources of hydroelectric power and supply a large portion of power to Zambia, Zimbabwe and South Africa.

Recently worrying reports have popped up in the press that the Zambezi Seaway Scheme, a project to open up the Zambezi to enable the transportation of goods and minerals from the hinterland, is back on the cards. Click here for full details and to leave your comments.

For years there has also been talk and plans of another Hydroelectric Dam to be built in the Batoka gorge just below Victoria Falls, of major concern is that these plans are very much alive again. To find out more please click on this link "Batoka Gorge Dam Project" as we continue to follow and oppose this threatening project.

The rivers beauty has attracted tourists from all over the world and provides great opportunities for game viewing and various water sports. Hippopotamus, crocodiles, elephants and lions are some examples of wildlife you will find along various parts of the Zambezi River.

Jai Ganesh · 2025-03-06 00:02:46

2380) Pulmonologist

Gist

A pulmonologist is a physician who specializes in the respiratory system. From the windpipe to the lungs, if your complaint involves the lungs or any part of the respiratory system, a pulmonologist is the doc you want to solve the problem. Pulmonology is a medical field of study within internal medicine.

A pulmonologist is a physician who specializes in lung conditions. They diagnose and treat diseases of the respiratory system, including your airways, alveoli (air sacs in your lungs) and blood vessels.

Pulmonology: A branch of medicine that specializes in diagnosing and treating diseases of the lungs and other parts of the respiratory system. These diseases include asthma, emphysema, tuberculosis, and pneumonia.

Summary

A pulmonologist is a healthcare provider that specializes in diagnosing and treating conditions that affect your respiratory system, including your airways and lungs. You might see a pulmonologist if you have a chronic condition that affects your breathing or if you have symptoms like chronic cough, shortness of breath or wheezing.

Overview:

What is a pulmonologist?

A pulmonologist is a physician who specializes in lung conditions. They diagnose and treat diseases of the respiratory system, including your airways, alveoli (air sacs in your lungs) and blood vessels.

You might hear people call pulmonologists lung doctors, lung specialists or chest doctors.

What does a pulmonologist do?

A pulmonologist can diagnose and treat respiratory system diseases. They might have certain areas that they specialize in, like critical care, asthma or sleep medicine. They might also specialize in treating certain age groups, like kids younger than 18 (pediatric pulmonologists) or people over 65 (geriatric pulmonologists).

What conditions do pulmonologists treat?

Pulmonologists treat various respiratory conditions and illnesses, including:

* Asbestosis.
* Aspergillosis.
* Asthma.
* Bronchiectasis.
* Bronchitis.
* Chronic beryllium disease (berylliosis).
* Chronic obstructive pulmonary disease (COPD).
* Coal workers’ pneumoconiosis (black lung disease).
* Cystic fibrosis.
* Emphysema.
* Interstitial lung disease.
* Long COVID.
* Lung cancer.
* Pulmonary hypertension.
* Sarcoidosis.
* Silicosis.
* Sleep apnea.
* Tuberculosis.

Why would you need to see a pulmonologist?

If you have a respiratory condition that requires specialized testing, your primary care provider might refer you to a pulmonologist. Symptoms you might see a pulmonologist for include:

* A cough that doesn’t improve over time (chronic cough).
* Shortness of breath (dyspnea).
* Asthma attacks.
* Chest pain or tightness.
* Wheezing.
* Sleep apnea symptoms, like daytime tiredness or snoring.

What will a pulmonologist do on the first visit?

If it’s your first appointment with a pulmonologist, they’ll take a detailed medical history and do a physical examination. During this time, you can talk with your healthcare provider about the reasons you’re there and explain the details of your symptoms.

You might find it helpful to prepare notes in advance about things like:

* How long you’ve had symptoms.
* If you’ve noticed anything that triggers your symptoms (like respiratory illnesses, stress or seasonal changes).
* Anything you’ve noticed that makes your symptoms better or worse.
* Whether you smoke or vape, or if you used to.
* Whether your job, hobbies or living conditions could’ve exposed to you allergens or lung irritants (like secondhand smoke, chemicals, grains, livestock or birds).
* Whether anyone in your family has a respiratory condition.
* Any questions you have.

Before the end of the appointment, your provider might:

* Order tests.
* Schedule a follow-up visit.
* Recommend or prescribe treatments.
* Refer you to another provider.

What tests does a pulmonologist run?

Your pulmonologist might order some tests to help with diagnosis and treatment. These might include:

* Blood tests.
* Imaging tests like chest X-rays or CT scans (computed tomography scans).
* Pulmonary function tests.
* Spirometry.
* Bronchoscopy.
* Sleep studies.

You may have to repeat these tests in the future or have additional testing to confirm results.

Details

A pulmonologist is a doctor who diagnoses and treats diseases of the respiratory system -- the lungs and other organs that help you breathe.

For some relatively short-lasting illnesses that affect your lungs, like the flu or pneumonia, you might be able to get all the care you need from your regular doctor. But if your cough, shortness of breath, or other symptoms don't get better, you might need to see a pulmonologist.

What is pulmonology?

Internal medicine is the type of medical care that deals with adult health, and pulmonology is one of its many fields. Pulmonologists focus on the respiratory system and diseases that affect it. The respiratory system includes your:

* Mouth and nose
* Sinuses
* Throat (pharynx)
* Voice box (larynx)
* Windpipe (trachea)
* Bronchial tubes
* Lungs and things inside them like bronchioles and alveoli
* Diaphragm

What Conditions Do Pulmonologists Treat?

A pulmonologist can treat many kinds of lung problems. These include:

* Asthma, a disease that inflames and narrows your airways and makes it hard to breathe
* Chronic obstructive pulmonary disease (COPD), a group of lung diseases that includes emphysema and chronic bronchitis
* Cystic fibrosis, a disease caused by changes in your genes that makes sticky mucus build up in your lungs
* Emphysema, which damages the air sacs in your lungs
* Interstitial lung disease, a group of conditions that scar and stiffen your lungs
* Lung cancer, a type of cancer that starts in the lungs
* Obstructive sleep apnea, which causes repeated pauses in your breathing while you sleep
* Pulmonary hypertension, or high blood pressure in the arteries of your lungs
* Tuberculosis, a bacterial infection of the lungs
* Bronchiectasis, which damages your airways so they widen and become flabby or scarred
* Bronchitis, which is when your airways are inflamed, with a cough and extra mucus. It can lead to an infection.
* Pneumonia, an infection that makes the air sacs (alveoli) in your lungs inflamed and filled with pus
* COVID-19 pneumonia, which can cause severe breathing problems and respiratory failure

What Kind of Training Do Pulmonologists Have?

A pulmonologist's training starts with a medical school degree. Then, they do an internal medicine residency at a hospital for 3 years to get more experience. After their residency, doctors can get certified in internal medicine by the American Board of Internal Medicine.

That's followed by years of specialized training as a fellow in pulmonary medicine. Finally, they must pass specialty exams to become board-certified in pulmonology. Some doctors get even more training in Interventional Pulmonary, pulmonary hypertension, and lung transplantation. Others might specialize in younger or older patients.

How Do Pulmonologists Diagnose Lung Diseases?

Pulmonologists use tests to figure out what kind of lung problem you have. They might ask you to get:

* Blood tests. They check levels of oxygen and other things in your blood.
* Bronchoscopy. It uses a thin, flexible tube with a camera on the end to see inside your lungs and airways.
* X-rays. They use low doses of radiation to make images of your lungs and other things in your chest.
* CT scan. It's a powerful X-ray that makes detailed pictures of the inside of your chest.
* Spirometry. This tests how well your lungs work by measuring how hard you can breathe air in and out.

What Kinds of Procedures Do Pulmonologists Do?

Pulmonologists can do special procedures such as:

* Pulmonary hygiene. This clears fluid and mucus from your lungs.
* Airway ablation. This opens blocked air passages or eases difficult breathing.
* Biopsy. This takes tissue samples to diagnose disease.
* Bronchoscopy. This looks inside your lungs and airways to diagnose disease.

Why See a Pulmonologist

You might see a pulmonologist if you have symptoms such as:

* A cough that is severe or that lasts more than 3 weeks
* Chest pain
* Wheezing
* Dizziness
* Trouble breathing
* Severe tiredness
* Asthma that’s hard to control
* Bronchitis or a cold that keeps coming back.

Additional Information

Pulmonology is a medical specialty that deals with diseases involving the respiratory tract. It is also known as respirology, respiratory medicine, or chest medicine in some countries and areas.

Pulmonology is considered a branch of internal medicine, and is related to intensive care medicine. Pulmonology often involves managing patients who need life support and mechanical ventilation. Pulmonologists are specially trained in diseases and conditions of the chest, particularly pneumonia, asthma, tuberculosis, emphysema, and complicated chest infections.

Pulmonology/respirology departments work especially closely with certain other specialties: cardiothoracic surgery departments and cardiology departments.

History of pulmonology

One of the first major discoveries relevant to the field of pulmonology was the discovery of pulmonary circulation. Originally, it was thought that blood reaching the right side of the heart passed through small 'pores' in the septum into the left side to be oxygenated, as theorized by Galen; however, the discovery of pulmonary circulation disproves this theory, which had previously been accepted since the 2nd century. Thirteenth-century anatomist and physiologist Ibn Al-Nafis accurately theorized that there was no 'direct' passage between the two sides (ventricles) of the heart. He believed that the blood must have passed through the pulmonary artery, through the lungs, and back into the heart to be pumped around the body. This is believed by many to be the first scientific description of pulmonary circulation.

Although pulmonary medicine only began to evolve as a medical specialty in the 1950s, William Welch and William Osler founded the 'parent' organization of the American Thoracic Society, the National Association for the Study and Prevention of Tuberculosis. The care, treatment, and study of tuberculosis of the lung is recognised as a discipline in its own right, phthisiology. When the specialty did begin to evolve, several discoveries were being made linking the respiratory system and the measurement of arterial blood gases, attracting more and more physicians and researchers to the developing field.

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Jai Ganesh · 2025-03-07 00:03:09

2381) Silvering

Gist

Silvering is process of making mirrors by coating glass with silver, discovered by the German chemist Justus von Liebig in 1835. In the process silver–ammonia compounds are reduced chemically to metallic silver, which is deposited on a suitably shaped glass surface.

Summary

Silvering is process of making mirrors by coating glass with silver, discovered by the German chemist Justus von Liebig in 1835. In the process silver–ammonia compounds are reduced chemically to metallic silver, which is deposited on a suitably shaped glass surface. Modern processes may utilize silver solutions and reducer solutions—consisting of invert sugar, Rochelle salt, or formaldehyde—that meet in a spray above clean glass traveling on a conveyor; as the spray falls on the glass surface, metallic silver is deposited.

Silvering of partial reflectors, for optical and physics research applications, must be done by a process slow enough so that the amount of reflectivity can be controlled. Partial reflectors transmit and reflect only portions of the incident light. Special mirrors for such instruments as reflecting telescopes are usually silvered by evaporation of silver onto a surface from an electrically heated filament in high vacuum.

Details

Silvering is the chemical process of coating a non-conductive substrate such as glass with a reflective substance, to produce a mirror. While the metal is often silver, the term is used for the application of any reflective metal.

Process

Most common household mirrors are "back-silvered" or "second-surface", meaning that the light reaches the reflective layer after passing through the glass. A protective layer of paint is usually applied to protect the back side of the reflective surface . This arrangement protects the fragile reflective layer from corrosion, scratches, and other damage. However, the glass layer may absorb some of the light and cause distortions and optical aberrations due to refraction at the front surface, and multiple additional reflections on it, giving rise to "ghost images" (although some optical mirrors such as Mangins take advantage of it).

Therefore, precision optical mirrors normally are "front-silvered" or "first-surface", meaning that the reflective layer is on the surface towards the incoming light. The substrate normally provides only physical support, and need not be transparent. A hard, protective, transparent overcoat may be applied to prevent oxidation of the reflective layer and scratching of the metal. Front-coated mirrors achieve reflectivities of 90–95% when new.

History

Ptolemaic Egypt had manufactured small glass mirrors backed by lead, tin, or antimony. In the early 10th century, the Persian scientist al-Razi described ways of silvering and gilding in a book on alchemy, but this was not done for the purpose of making mirrors.

Tin-coated mirrors were first made in Europe in the 15th century. The thin tinfoil used to silver mirrors was known as "tain". When glass mirrors first gained widespread usage in Europe during the 16th century, most were silvered with an amalgam of tin and mercury,

In 1835 German chemist Justus von Liebig developed a process for depositing silver on the rear surface of a piece of glass; this technique gained wide acceptance after Liebig improved it in 1856. The process was further refined and made easier by the chemist Tony Petitjean (1856). This reaction is a variation of the Tollens' reagent for aldehydes. A diamminesilver(I) solution is mixed with a sugar and sprayed onto the glass surface. The sugar is oxidized by silver(I), which is itself reduced to silver(0), i.e. elemental silver, and deposited onto the glass.

In 1856-1857 Karl August von Steinheil and Léon Foucault introduced the process of depositing an ultra-thin layer of silver on the front surface of a piece of glass, making the first optical-quality first surface glass mirrors, replacing the use of speculum metal mirrors in reflecting telescopes. These techniques soon became standard for technical equipment.

An aluminum vacuum-deposition process invented in 1930 by Caltech physicist and astronomer John Strong, led to most reflecting telescopes shifting to aluminum. Nevertheless, some modern telescopes use silver, such as the Kepler Space Telescope. The Kepler mirror's silver was deposited using ion assisted evaporation.

Modern silvering processes:

General processes

Silvering aims to produce a non-crystalline coating of amorphous metal (metallic glass), with no visible artifacts from grain boundaries. The most common methods in current use are electroplating, chemical "wet process" deposition, and vacuum deposition.

Electroplating of a substrate of glass or other non-conductive material requires the deposition of a thin layer of conductive but transparent material, such as carbon. This layer tends to reduce the adhesion between the metal and the substrate. Chemical deposition can result in better adhesion, directly or by pre-treatment of the surface.

Vacuum deposition can produce very uniform coating with very precisely controlled thickness.

Metals:

Silver

The reflective layer on a second surface mirror such as a household mirror is often actual silver. A modern "wet" process for silver coating treats the glass with tin(II) chloride to improve the bonding between silver and glass. An activator is applied after the silver has been deposited to harden the tin and silver coatings. A layer of copper may be added for long-term durability.

Silver would be ideal for telescope mirrors and other demanding optical applications, since it has the best initial front-surface reflectivity in the visible spectrum. However, it quickly oxidizes and absorbs atmospheric sulfur to create a dark, low-reflectivity tarnish.

Aluminum

The "silvering" on precision optical instruments such as telescopes is usually aluminum. Although aluminum also oxidizes quickly, the thin aluminum oxide (sapphire) layer is transparent, and so the high-reflectivity underlying aluminum stays visible.

In modern aluminum silvering, a sheet of glass is placed in a vacuum chamber with electrically heated nichrome coils that can evaporate aluminum. In a vacuum, the hot aluminum atoms travel in straight lines. When they hit the surface of the mirror, they cool and stick.

Some mirror makers evaporate a layer of quartz or beryllia on the mirror; others expose it to pure oxygen or air in an oven so that it will form a tough, clear layer of aluminum oxide.

Tin

The first tin-coated glass mirrors were produced by applying a tin-mercury amalgam to the glass and heating the piece to evaporate the mercury.

Gold

The "silvering" on infrared instruments is usually gold. It has the best reflectivity in the infrared spectrum, and has high resistance to oxidation and corrosion. Conversely, a thin gold coating is used to create optical filters which block infrared (by mirroring it back towards the source) while passing visible light.

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Jai Ganesh · Yesterday 00:03:15

2383) Tissue paper

Gist

Hygienic tissue paper is commonly for personal use as facial tissue (paper handkerchiefs), napkins, bathroom tissue and household towels. Paper has been used for hygiene purposes for centuries, but tissue paper as we know it today was not produced in the United States before the mid-1940s.

Compared to cloth handkerchiefs and towels tissue papers are more hygienic since they are disposable items and are thrown away after use. This prevents the transfer of nasal fluids from one person to another and stops the spread of infectious diseases.

Details

Tissue paper, or simply tissue, is a lightweight paper or light crêpe paper. Tissue can be made from recycled paper pulp on a paper machine.

Tissue paper is very versatile, and different kinds are made to best serve these purposes, which are hygienic tissue paper, facial tissues, paper towels, as packing material, among other (sometimes creative) uses.

The use of tissue paper is common in developed nations, around 21 million tonnes in North America and 6 million in Europe, and is growing due to urbanization. As a result, the industry has often been scrutinized for deforestation. However, more companies are presently using more recycled fibres in tissue paper.

Properties

The key properties of tissues are absorbency, basis weight, thickness, bulk (specific volume), brightness, stretch, appearance and comfort.

Production

Tissue paper is produced on a paper machine that has a single large steam heated drying cylinder (Yankee dryer) fitted with a hot air hood. The raw material is paper pulp. The Yankee cylinder is sprayed with adhesives to make the paper stick. Creping is done by the Yankee's doctor blade that is scraping the dry paper off the cylinder surface. The crinkle (crêping) is controlled by the strength of the adhesive, geometry of the doctor blade, speed difference between the Yankee and final section of the paper machine and paper pulp characteristics.

The highest water absorbing applications are produced with a through air drying (TAD) process. These papers contain high amounts of NBSK and CTMP. This gives a bulky paper with high wet tensile strength and good water holding capacity. The TAD process uses about twice the energy compared with conventional drying of paper.

The properties are controlled by pulp quality, crêping and additives (both in base paper and as coating). The wet strength is often an important parameter for tissue.

Applications:

Hygienic tissue paper

Hygienic tissue paper is commonly for personal use as facial tissue (paper handkerchiefs), napkins, bathroom tissue and household towels. Paper has been used for hygiene purposes for centuries, but tissue paper as we know it today was not produced in the United States before the mid-1940s. In Western Europe large scale industrial production started in the beginning of the 1960s.

Facial tissues

Facial tissue (paper handkerchiefs) refers to a class of soft, absorbent, disposable paper that is suitable for use on the face. The term is commonly used to refer to the type of facial tissue, usually sold in boxes, that is designed to facilitate the expulsion of nasal mucus although it may refer to other types of facial tissues including napkins and wipes.

The first tissue handkerchiefs were introduced in the 1920s. They have been refined over the years, especially for softness and strength, but their basic design has remained constant. Today each person in Western Europe uses about 200 tissue handkerchiefs a year, with a variety of 'alternative' functions including the treatment of minor wounds, the cleaning of face and hands and the cleaning of spectacles.

The importance of the paper tissue on minimising the spread of an infection has been highlighted in light of fears over a swine flu epidemic. In the UK, for example, the Government ran a campaign called "Catch it, Bin it, Kill it", which encouraged people to cover their mouth with a paper tissue when coughing or sneezing.

Pressure on use of tissue papers has grown in the wake of improved hygiene concerns in response to the coronavirus pandemic.

Paper towels

Paper towels are the second largest application for tissue paper in the consumer sector. This type of paper has usually a basis weight of 20 to 24 g/{m}^{2}. Normally such paper towels are two-ply. This kind of tissue can be made from 100% chemical pulp to 100% recycled fibre or a combination of the two. Normally, some long fibre chemical pulp is included to improve strength.

Wrapping tissue

Wrapping tissue is a type of thin, translucent tissue paper used for wrapping/packing various articles and cushioning fragile items.

Custom-printed wrapping tissue is becoming a popular trend for boutique retail businesses. There are various on-demand custom printed wrapping tissue paper available online. Sustainably printed custom tissue wrapping paper are printed on FSC-certified, acid-free paper; and only use soy-based inks.

Toilet paper

Rolls of toilet paper have been available since the end of the 19th century. Today, more than 20 billion rolls of toilet tissue are used each year in Western Europe.[4] Toilet paper brands include, Andrex (United Kingdom), Charmin (United States) and Quilton (Australia), among many others.

Table napkins

Table napkins can be made of tissue paper. These are made from one up to four plies and in a variety of qualities, sizes, folds, colours and patterns depending on intended use and prevailing fashions. The composition of raw materials varies a lot from deinked to chemical pulp depending on quality.

Acoustic disrupter

In the late 1970s and early 1980s, a sound recording engineer named Bob Clearmountain was said to have hung tissue paper over the tweeter of his pair of Yamaha NS-10 speakers to tame the over-bright treble coming from it.

The phenomenon became the subject of hot debate and an investigation into the sonic effects of many different types of tissue paper. The authors of a study for Studio Sound magazine suggested that had the speakers' grilles been used in studios, they would have had the same effect on the treble output as the improvised tissue paper filter. Another tissue study found inconsistent results with different paper, but said that tissue paper generally demonstrated an undesirable effect known as "comb filtering", where the high frequencies are reflected back into the tweeter instead of being absorbed. The author derided the tissue practice as "aberrant behavior", saying that engineers usually fear comb filtering and its associated cancellation effects, suggesting that more controllable and less random electronic filtering would be preferable.

Road repair

Tissue paper, in the form of standard single-ply toilet paper, is commonly used in road repair to protect crack sealants. The sealants require upwards of 40 minutes to cure enough to not stick onto passing traffic. The application of toilet paper removes the stickiness and keeps the tar in place, allowing the road to be reopened immediately and increasing road repair crew productivity. The paper breaks down and disappears in the following days. The use has been credited to Minnesota Department of Transportation employee Fred Muellerleile, who came up with the idea in 1970 after initially trying standard office paper, which worked, but did not disintegrate easily.

Packing industry

Apart from above, a range of speciality tissues are also manufactured to be used in the packing industry. These are used for wrapping/packing various items, cushioning fragile items, stuffing in shoes/bags etc. to keep shape intact or, for inserting in garments etc. while packing/folding to keep them wrinkle free and safe. It is generally used printed with the manufacturers brand name or, logo to enhance the look and aesthetic appeal of the product. It is a type of thin, translucent paper generally in the range of grammages between 17 and 40 GSM, that can be rough or, shining, hard or soft, depending upon the nature of use.

Origami

The use of double-tissue, triple-tissue, tissue-foil and Methyl cellulose coated tissue papers are gaining increasing popularity. Due to the paper's low grammage the paper can be folded into intricate models when treated with Methyl Cellulose (also referred to as MC). The inexpensive paper provides incredible paper memory paired with paper strength (when MC treated). Origami models sometimes require both thin and highly malleable papers, for this tissue-foil is considered a prime choice.

The industry

Consumption of tissue in North America is three times greater than in Europe: out of the world's estimated production of 21 million tonnes (21,000,000 long tons; 23,000,000 short tons) of tissue, Europe produces approximately 6 million tonnes (5,900,000 long tons; 6,600,000 short tons).

The European tissue market is worth approximately 10 billion Euros annually and is growing at a rate of around 3%. The European market represents around 23% of the global market. Of the total paper and board market tissue accounts for 10%. An analysis and market research in Europe, Germany was one of the top tissue-consuming countries in Western Europe while Sweden was on top of the per-capita consumption of tissue paper in Western Europe. Market Study.

In Europe, the industry is represented by the European Tissue Symposium (ETS), a trade association. The members of ETS represent the majority of tissue paper producers throughout Europe and about 90% of total European tissue production. ETS was founded in 1971 and is based in Brussels since 1992.

In the U.S., the tissue industry is organized in the AF&PA.

Tissue paper production and consumption is predicted to continue to grow because of factors like urbanization, increasing disposable incomes and consumer spending. In 2015, the global market for tissue paper was growing at per annum rates between 8–9% (China, currently 40% of global market) and 2–3% (Europe). During the COVID-19 pandemic, tissue demand for homes increased dramatically as people spent more time in their homes, while commercial demand for the product decreased.

Companies

The largest tissue producing companies by capacity – some of them also global players – in 2015 are (in descending order):

* Essity
* Kimberly-Clark
* Georgia-Pacific
* Asia Pulp & Paper (APP)/Sinar Mas
* Procter & Gamble
* Sofidel Group
* CMPC
* WEPA Hygieneprodukte
* Metsä Group
* Cascades

Sustainability

The paper industry in general has a long history of accusations for being responsible for global deforestation through legal and illegal logging. The World Wide Fund for Nature (WWF — formerly the World Wildlife Fund) has urged Asia Pulp & Paper (APP), "one of the world's most notorious deforesters" especially in Sumatran rain forests, to become an environmentally responsible company; in 2012, the WWF launched a campaign to remove a brand of toilet paper known to be made from APP fiber from grocery store shelves. According to the Worldwatch Institute, the world per capita consumption of toilet paper was 3.8 kilograms in 2005. The WWF estimates that "every day, about 270,000 trees are flushed down the drain or end up as garbage all over the world", a rate of which about 10% are attributable to toilet paper alone.

Meanwhile, the paper tissue industry, along with the rest of the paper manufacturing sector, has worked to minimise its impact on the environment. Recovered fibres now represent some 46.5% of the paper industry's raw materials. The industry relies heavily on biofuels (about 50% of its primary energy). Its specific primary energy consumption has decreased by 16% and the specific electricity consumption has decreased by 11%, due to measures such as improved process technology and investment in combined heat and power (CHP). Specific carbon dioxide emissions from fossil fuels decreased by 25% due to process-related measures and the increased use of low-carbon and biomass fuels. Once consumed, most forest-based paper products start a new life as recycled material or biofuel.

EDANA, the trade body for the non-woven absorbent hygiene products industry (which includes products such as household wipes for use in the home) has reported annually on the industry's environmental performance since 2005. Less than 1% of all commercial wood production ends up as wood pulp in absorbent hygiene products. The industry contributes less than 0.5% of all solid waste and around 2% of municipal solid waste (MSW) compared with paper and board, garden waste and food waste which each comprise between 18 and 20 percent of MSW.

There has been a great deal of interest, in particular, in the use of recovered fibres to manufacture new tissue paper products. However, whether this is actually better for the environment than using new fibres is open to question. A life-cycle assessment study indicated that neither fibre type can be considered environmentally preferable. In this study both new fibre and recovered fibre offer environmental benefits and shortcomings.

Total environmental impacts vary case by case, depending on for example the location of the tissue paper mill, availability of fibres close to the mill, energy options and waste utilization possibilities. There are opportunities to minimise environmental impacts when using each fibre type.

When using recovered fibres, it is beneficial to:

* Source fibres from integrated deinking operations to eliminate the need for thermal drying of fibre or long distance transport of wet pulp,
* Manage deinked sludge in order to maximise beneficial applications and minimise waste burden on society; and
* Select the recovered paper depending on the end-product requirements and that also allows the most efficient recycling process.

When using new fibres, it is beneficial to:

* Manage the raw material sources to maintain legal, sustainable forestry practices by implementing processes such as forest certification systems and chain of custody standards; and
* Consider opportunities to introduce new and more renewable energy sources and increase the use of biomass fuels to reduce emissions of carbon dioxide.

When using either fibre type, it is beneficial to:

* Improve energy efficiency in tissue manufacturing;
* Examine opportunities for changing to alternative, non fossil based sources, of energy for tissue manufacturing operations
* Deliver products that maximise functionality and optimize consumption; and
* Investigate opportunities for alternative product disposal systems that minimize the environmental impact of used products.

The Confederation of European Paper Industries (CEPI) has published reports focusing on the industry's environmental credentials. In 2002, it noted that "a little over 60% of the pulp and paper produced in Europe comes from mills certified under one of the internationally recognised eco-management schemes". There are a number of ‘eco-labels’ designed to help consumers identify paper tissue products which meet such environmental standards. Eco-labelling entered mainstream environmental policy-making in the late seventies, first with national schemes such as the German Blue Angel programme, to be followed by the Nordic swan (1989). In 1992 a European eco-labelling regulation, known as the EU Flower, was also adopted. The stated objective is to support sustainable development, balancing environmental, social and economical criteria.

In 2019, the NRDC and Stand.earth released a report grading various brands of toilet paper, paper towels, and facial tissue; the report criticized major brands for lacking recycled material.

Types of eco-labels

There are three types of eco-labels, each defined by ISO (International Organization for Standardization).

Type I: ISO 14024 This type of eco-label is one where the criteria are set by third parties (not the manufacturer). They are in theory based on life cycle impacts and are typically based on pass/fail criteria. The one that has European application is the EU Flower.

Type II: ISO 14021 These are based on the manufacturers or retailers own declarations. Well known amongst these are claims of "100% recycled" in relation to tissue/paper.

Type III: ISO 14025 These claims give quantitative details of the impact of the product based on its life cycle. Sometimes known as EPDs (Environmental Product Declarations), these labels are based on an independent review of the life cycle of the product. The data supplied by the manufacturing companies are also independently reviewed.

The most well known example in the paper industry is the Paper Profile. You can tell a Paper Profile meets the Type III requirements when the verifiers logo is included on the document.

An example of an organization that sets standards is the Forest Stewardship Council.

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