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#1251 2022-01-11 22:01:39

ganesh
Administrator
Registered: 2005-06-28
Posts: 35,485

Re: Miscellany

1227) Malic Acid

Summary

Malic acid is an organic compound with the molecular formula C4H6O5. It is a dicarboxylic acid that is made by all living organisms, contributes to the sour taste of fruits, and is used as a food additive. Malic acid has two stereoisomeric forms (L- and D-enantiomers), though only the L-isomer exists naturally. The salts and esters of malic acid are known as malates. The malate anion is an intermediate in the citric acid cycle.

Etymology

The word 'malic' is derived from Latin 'mālum', meaning 'apple'. The related Latin word 'mālus', meaning 'apple tree', is used as the name of the genus Malus, which includes all apples and crabapples; and the origin of other taxonomic classifications such as Maloideae, Malinae, and Maleae.

Biochemistry

L-Malic acid is the naturally occurring form, whereas a mixture of L- and D-malic acid is produced synthetically.

Malate plays an important role in biochemistry. In the C4 carbon fixation process, malate is a source of CO2 in the Calvin cycle. In the citric acid cycle, (S)-malate is an intermediate, formed by the addition of an -OH group on the si face of fumarate. It can also be formed from pyruvate via anaplerotic reactions.

Malate is also synthesized by the carboxylation of phosphoenolpyruvate in the guard cells of plant leaves. Malate, as a double anion, often accompanies potassium cations during the uptake of solutes into the guard cells in order to maintain electrical balance in the cell. The accumulation of these solutes within the guard cell decreases the solute potential, allowing water to enter the cell and promote aperture of the stomata.

In food

Malic acid was first isolated from apple juice by Carl Wilhelm Scheele in 1785. Antoine Lavoisier in 1787 proposed the name acide malique, which is derived from the Latin word for apple, mālum—as is its genus name Malus. In German it is named Äpfelsäure (or Apfelsäure) after plural or singular of the fruit apple, but the salt(s) Malat(e). Malic acid is the main acid in many fruits, including apricots, blackberries, blueberries, cherries, grapes, mirabelles, peaches, pears, plums, and quince and is present in lower concentrations in other fruits, such as citrus. It contributes to the sourness of unripe apples. Sour apples contain high proportions of the acid. It is present in grapes and in most wines with concentrations sometimes as high as 5 g/l. It confers a tart taste to wine; the amount decreases with increasing fruit ripeness. The taste of malic acid is very clear and pure in rhubarb, a plant for which it is the primary flavor. It is also a component of some artificial vinegar flavors, such as "salt and vinegar" flavored potato chips.

In citrus, fruits produced in organic farming contain higher levels of malic acid than fruits produced in conventional agriculture.

The process of malolactic fermentation converts malic acid to much milder lactic acid. Malic acid occurs naturally in all fruits and many vegetables, and is generated in fruit metabolism.

Malic acid, when added to food products, is denoted by E number E296. It is sometimes used with or in place of the less sour citric acid in sour sweets. These sweets are sometimes labeled with a warning stating that excessive consumption can cause irritation of the mouth. It is approved for use as a food additive in the EU, US and Australia and New Zealand (where it is listed by its INS number 296).

Malic acid contains 10 kJ (2.39 kilocalories) of energy per gram.

Production and main reactions

Racemic malic acid is produced industrially by the double hydration of maleic anhydride. In 2000, American production capacity was 5000 tons per year. The enantiomers may be separated by chiral resolution of the racemic mixture. S-Malic acid is obtained by fermentation of fumaric acid.

Self-condensation of malic acid in the presence of fuming sulfuric acid gives the pyrone coumalic acid:

Malic acid was important in the discovery of the Walden inversion and the Walden cycle, in which (−)-malic acid first is converted into (+)-chlorosuccinic acid by action of phosphorus pentachloride. Wet silver oxide then converts the chlorine compound to (+)-malic acid, which then reacts with PCl5 to the (−)-chlorosuccinic acid. The cycle is completed when silver oxide takes this compound back to (−)-malic acid.

Uses

l-malic acid is used to resolve α-phenylethylamine, a versatile resolving agent in its own right.

Plant defense

Soil supplementation with molasses increases microbial synthesis of MA. This is thought to occur naturally as part of soil microbe suppression of disease, and so soil amendment with molasses can be used as a crop treatment in horticulture.

Details

Overview

Malic acid is a chemical found in certain fruits and wines. It is sometimes used as medicine.

Malic acid is used most commonly for dry mouth. It is also used for fibromyalgia, fatigue, and skin conditions, but there is no good scientific evidence to support these other uses.

In foods, malic acid is used as a flavoring agent to give food a tart taste.

In manufacturing, malic acid is used to adjust the acidity of cosmetics.

How does it work ?

Malic acid is involved in the Krebs cycle. This is a process the body uses to make energy. Malic acid is sour and acidic. This helps to clear away dead skin cells when applied to the skin. Its sourness also helps to make more saliva to help with dry mouth.

Uses & Effectiveness ?

Possibly Effective for:

* Dry mouth. Using a mouth spray or sucking on a tablet containing malic acid seems to improve symptoms of dry mouth better than using a saline mouth spray or citric acid oral rinse.
Insufficient Evidence for
* Acne. Early research shows that applying an alpha hydroxy acid cream containing malic acid helps reduce signs of acne in some people.
* Fibromyalgia. Taking malic acid in combination with magnesium seems to reduce pain and tenderness caused by fibromyalgia.
* Persistent heartburn. Early research shows that taking malic acid in combination with omeprazole may improve some symptoms of heartburn better than omeprazole alone.
* Fatigue.
* Warts.
* Scaly, itchy skin (psoriasis).
* Aging skin.
* Other conditions.

More evidence is needed to rate the effectiveness of malic acid for these uses.

Side Effects

When taken by mouth: Malic acid is LIKELY SAFE when taken by mouth in food amounts. Malic acid is POSSIBLY SAFE when taken by mouth as a medicine.

When applied to the inside of the mouth: Malic acid is POSSIBLY SAFE when applied to the inside of the mouth as a spray or lozenge.

When applied to the skin: There isn't enough reliable information to know if malic acid is safe. It might cause side effects such as skin and eye irritation.

Special Precautions and Warnings

Pregnancy and breast-feeding: Malic acid is LIKELY SAFE when taken by mouth in food amounts. There isn't enough reliable information to know if malic acid is safe to use as medicine when pregnant or breast-feeding. Stay on the safe side and avoid in amounts greater than what is normally found in food.

Low blood pressure: Malic acid might lower blood pressure. In theory, malic acid might increase the risk of blood pressure becoming too low in people prone to low blood pressure.

Moderate Interaction:

Be cautious with this combination.

Medications for high blood pressure (Antihypertensive drugs) interacts with MALIC ACID

Malic acid might lower blood pressure. Taking malic acid along with medications for high blood pressure might cause your blood pressure to go too low.

Some medications for high blood pressure include captopril (Capoten), enalapril (Vasotec), losartan (Cozaar), valsartan (Diovan), diltiazem (Cardizem), amlodipine (Norvasc), hydrochlorothiazide (HydroDiuril), furosemide (Lasix), and many others.

Dosing

The following doses have been studied in scientific research:

ADULTS:

APPLIED TO THE INSIDE OF THE MOUTH:

For dry mouth: Mouth sprays (Xeros Dentaid, Dentaid; SalivAktive) containing 1% malic acid have been used up to 8 times daily for 2 weeks. Lozenges (Xeros Dentaid, Dentaid) containing malic acid 28.58 mg, xylitol, and fluoride have been used up to 4 times a day for 6 months.

814737_DL-Malic%20acid[814737_DL-Malic%20acid-ALL].jpg


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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#1252 2022-01-12 19:00:35

ganesh
Administrator
Registered: 2005-06-28
Posts: 35,485

Re: Miscellany

1228) Fire Extinguisher

Summary

A fire extinguisher is an active fire protection device used to extinguish or control small fires, often in emergency situations. It is not intended for use on an out-of-control fire, such as one which has reached the ceiling, endangers the user (i.e., no escape route, smoke, explosion hazard, etc.), or otherwise requires the equipment, personnel, resources and/or expertise of a fire brigade. Typically, a fire extinguisher consists of a hand-held cylindrical pressure vessel containing an agent that can be discharged to extinguish a fire. Fire extinguishers manufactured with non-cylindrical pressure vessels also exist but are less common.

There are two main types of fire extinguishers: stored-pressure and cartridge-operated. In stored pressure units, the expellant is stored in the same chamber as the firefighting agent itself. Depending on the agent used, different propellants are used. With dry chemical extinguishers, nitrogen is typically used; water and foam extinguishers typically use air. Stored pressure fire extinguishers are the most common type. Cartridge-operated extinguishers contain the expellant gas in a separate cartridge that is punctured prior to discharge, exposing the propellant to the extinguishing agent. This type is not as common, used primarily in areas such as industrial facilities, where they receive higher-than-average use. They have the advantage of simple and prompt recharge, allowing an operator to discharge the extinguisher, recharge it, and return to the fire in a reasonable amount of time. Unlike stored pressure types, these extinguishers use compressed carbon dioxide instead of nitrogen, although nitrogen cartridges are used on low temperature (–60 rated) models. Cartridge operated extinguishers are available in dry chemical and dry powder types in the U.S. and in water, wetting agent, foam, dry chemical (classes ABC and B.C.), and dry powder (class D) types in the rest of the world.

Fire extinguishers are further divided into handheld and cart-mounted (also called wheeled extinguishers). Handheld extinguishers weigh from 0.5 to 14 kilograms (1.1 to 30.9 lb), and are hence, easily portable by hand. Cart-mounted units typically weigh more than 23 kilograms (51 lb). These wheeled models are most commonly found at construction sites, airport runways, heliports, as well as docks and marinas.

Details

Fire extinguisher is a portable or movable apparatus used to put out a small fire by directing onto it a substance that cools the burning material, deprives the flame of oxygen, or interferes with the chemical reactions occurring in the flame. Water performs two of these functions: its conversion to steam absorbs heat, and the steam displaces the air from the vicinity of the flame. Many simple fire extinguishers, therefore, are small tanks equipped with hand pumps or sources of compressed gas to propel water through a nozzle. The water may contain a wetting agent to make it more effective against fires in upholstery, an additive to produce a stable foam that acts as a barrier against oxygen, or an antifreeze. Carbon dioxide is a common propellant, brought into play by removing the locking pin of the cylinder valve containing the liquefied gas; this method has superseded the process, used in the soda-acid fire extinguisher, of generating carbon dioxide by mixing sulfuric acid with a solution of sodium bicarbonate.

Numerous agents besides water are used; the selection of the most appropriate one depends primarily on the nature of the materials that are burning. Secondary considerations include cost, stability, toxicity, ease of cleanup, and the presence of electrical hazard.

Small fires are classified according to the nature of the burning material. Class A fires involve wood, paper, and the like; Class B fires involve flammable liquids, such as cooking fats and paint thinners; Class C fires are those in electrical equipment; Class D fires involve highly reactive metals, such as sodium and magnesium. Water is suitable for putting out fires of only one of these classes (A), though these are the most common. Fires of classes A, B, and C can be controlled by carbon dioxide, halogenated hydrocarbons such as halons, or dry chemicals such as sodium bicarbonate or ammonium dihydrogen phosphate. Class D fires ordinarily are combated with dry chemicals.

A primitive hand pump for directing water at a fire was invented by Ctesibius of Alexandria about 200 BCE, and similar devices were employed during the Middle Ages. In the early 1700s devices created independently by English chemists Ambrose Godfrey and French C. Hoppfer used explosive charges to disperse fire-suppressing solutions. English inventor Capt. George Manby introduced a handheld fire extinguisher—a three-gallon tank containing a pressurized solution of potassium carbonate—in 1817. Modern incarnations employing a variety of chemical solutions are essentially modifications of Manby’s design.

fire-extinguishers-500x500.jpg


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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#1253 2022-01-13 18:16:33

ganesh
Administrator
Registered: 2005-06-28
Posts: 35,485

Re: Miscellany

1229) Shock

Electric shock

Summary

Electrical injury

Electrical injury is a physiological reaction caused by electric current passing through the body. The injury depends on the density of the current, tissue resistance and duration of contact. Very small currents may be imperceptible or produce a light tingling sensation. A shock caused by low and otherwise harmless current could startle an individual and cause injury due to jerking away or falling. Stronger currents may cause some degree of discomfort or pain, while more intense currents may induce involuntary muscle contractions, preventing the person from breaking free of the source of electricity. Still larger currents result in tissue damage and may trigger ventricular fibrillation or cardiac arrest. Consequences of injury from electricity may include amputations, bone fractures and orthopedic and musculoskeletal injuries. If death results from an electric shock the cause of death is generally referred to as electrocution.

Electric injury occurs upon contact of a body part with electricity that causes a sufficient current to pass through the person's tissue. Contact with energized wiring or devices is the most common cause. In cases of exposure to high voltages, such as on a power transmission tower, direct contact may not be necessary as the voltage may "jump" the air gap to the electrical device.

Following an electrical injury from household current, if a person has no symptoms, no underlying heart problems, and is not pregnant further testing is not required. Otherwise an electrocardiogram, blood work to check the heart, and urine testing for signs of muscle breakdown may be performed.

Management may involve resuscitation, pain medications, wound management, and heart monitoring. Electrical injuries affect more than 30,000 people a year in the United States and result in about 1,000 deaths.

Details: Shock

Shock, in physiology, is failure of the circulatory system to supply sufficient blood to peripheral tissues to meet basic metabolic requirements for oxygen and nutrients and the incomplete removal of metabolic wastes from the affected tissues. Shock is usually caused by hemorrhage or overwhelming infection and is characterized in most cases by a weak, rapid pulse; low blood pressure; and cold, sweaty skin. Depending on the cause, however, some or all of these symptoms may be missing in individual cases.

A brief treatment of shock follows.

Shock may result from a variety of physiological mechanisms, including sudden reductions in the total blood volume through acute blood losses, as in severe hemorrhage; sudden reductions in cardiac output, as in myocardial infarction (heart attack); and widespread dilation of the blood vessels, as in some forms of infection. Whatever the central physiological mechanism, the effect of shock is to reduce blood flow through the small vessels, or capillaries, where oxygen and nutrients pass into the tissues and wastes are collected for removal.

Shock is usually classified on the basis of its presumed cause, although in many cases the true cause of the peripheral circulatory insufficiency may not be apparent. The most common cause of shock is massive loss of blood, either through trauma or through surgery. In the latter case, the blood loss can be anticipated and shock prevented by providing blood transfusions during and after the operation. An acute loss of blood reduces the amount of venous blood returning to the heart, in turn reducing the cardiac output and causing a drop in arterial blood pressure. Pressure receptors, or baroreceptors, in the walls of the aorta and carotid arteries trigger physiological reflexes to protect the central circulation, increasing heart rate to boost cardiac output and constricting small blood vessels to direct blood flow to essential organs. If the blood losses continue, even these mechanisms fail, producing a sharp drop in blood pressure and overt manifestations of shock. Loss of blood plasma in burns or dehydration can also lower blood volume sufficiently to induce shock.

The heart’s output can also be reduced sufficiently to produce shock without blood loss. In coronary thrombosis, the supply of blood to the heart muscle through the coronary artery is interrupted by a blood clot or vascular constriction; the damaged muscle may then lack strength to force a normal volume out of the heart with each stroke. Again, the diminished output triggers the baroreceptors in the arteries to restrict peripheral circulation. Blood clots that block the circulation of blood to the lungs (pulmonary emboli) or increase the fluid that surrounds and cushions the heart (cardiac tamponade) can also impair the pumping of the heart sufficiently to cause shock.

The most common cause of shock by dilation of the blood vessels is massive bacterial infection, which may be further exacerbated by reductions in total blood volume caused by fluid losses secondary to the infection. Generally, toxins produced by the bacteria are the cause of the dilation. Foreign substances in the bloodstream can also produce a form of shock, called anaphylactic shock, through allergic reactions causing blood vessels to dilate. Another possible cause of shock through vascular dilation is drugs; many anesthetic drugs create a controlled shock that must be carefully monitored by adjusting dosage, and overdoses of several such drugs, including barbiturates and narcotics, produce shock symptoms.

The chief problem in treating shock is to recognize the cause of the physiological problem, as several possible causes may coexist in a single patient, especially following an accident. Failure to distinguish between shock caused by inadequate cardiac output and that caused by fluid losses reducing blood volume can result in a therapeutic dilemma, since treatments that are effective for one kind of shock will aggravate the other. Intravenous fluids are the usual treatment for shock caused by loss of blood, but adding extra fluid to the circulation can overload a damaged heart that already has a reduced output, so that the shock deepens. When the cause of shock is unclear, physicians may make a trial using intravenous fluids; if the central venous pressure rises, indicating diminished cardiac capacity, the fluids are stopped before the heart can be further compromised. Shock secondary to bacterial infection may be treated by combined fluid replacement and appropriate antibiotics, while anaphylactic shock is combated with epinephrine and antihistamines, which counter the acute allergic response.

What You Should Know About Shock

What is shock?

The term “shock” may refer to a psychologic or a physiologic type of shock.

Psychologic shock is caused by a traumatic event and is also known as acute stress disorder. This type of shock causes a strong emotional response and may cause physical responses as well.

The focus of this article is on the multiple causes of physiologic shock.

Your body experiences shock when you don’t have enough blood circulating through your system to keep organs and tissues functioning properly.

It can be caused by any injury or condition that affects the flow of blood through your body. Shock can lead to multiple organ failure as well as life-threatening complications.

There are many types of shock. They fall under four main categories, based on what has affected the flow of blood. The four major types are:

* obstructive shock
* cardiogenic shock
* distributive shock
* hypovolemic shock

All forms of shock are life-threatening.

If you develop symptoms of shock, get medical help immediately.

What are the signs and symptoms of shock?

If you go into shock, you may experience one or more of the following:

* rapid, weak, or absent pulse
* irregular heartbeat
* rapid, shallow breathing
* lightheadedness
* cool, clammy skin
* dilated pupils
* lackluster eyes
* chest pain
* nausea
* confusion
* anxiety
* decrease in urine
* thirst and dry mouth
* low blood sugar
* loss of consciousness

What causes shock to occur?

Anything that affects the flow of blood through your body can cause shock. Some causes of shock include:

* severe allergic reaction
* significant blood loss
* heart failure
* blood infections
* dehydration
* poisoning
* burns

What are the major types of shock?

There are four major types of shock, each of which can be caused by a number of different events.

Obstructive shock

Obstructive shock occurs when blood can’t get where it needs to go. A pulmonary embolism is one condition that may cause an interruption to blood flow. Conditions that can cause a buildup of air or fluid in the chest cavity can also lead to obstructive shock. These include:

* pneumothorax (collapsed lung)
* hemothorax (blood collects in the space between the chest wall and lung)
* cardiac tamponade (blood or fluids fill the space between the sac that surrounds the heart and the heart muscle)

Cardiogenic shock

Damage to your heart can decrease the blood flow to your body, leading to cardiogenic shock. Common causes of cardiogenic shock include:

* damage to your heart muscle
* irregular heart rhythm
* very slow heart rhythm

Distributive shock

Conditions that cause your blood vessels to lose their tone can cause distributive shock. When your blood vessels lose their tone, they can become so open and floppy that not enough blood pressure supplies your organs. Distributive shock can result in symptoms including:

* flushing
* low blood pressure
* loss of consciousness

There are a number of types of distributive shock, including the following:

Anaphylactic shock is a complication of a severe allergic reaction known as anaphylaxis. Allergic reactions occur when your body mistakenly treats a harmless substance as harmful. This triggers a dangerous immune response.

Anaphylaxis is usually caused by allergic reactions to food, insect venom, medications, or latex.

Septic shock is another form of distributive shock. Sepsis, also known as blood poisoning, is a condition caused by infections that lead to bacteria entering your bloodstream. Septic shock occurs when bacteria and their toxins cause serious damage to tissues or organs in your body.

Neurogenic shock is caused by damage to the central nervous system, usually a spinal cord injury. This causes blood vessels to dilate, and the skin may feel warm and flushed. The heart rate slows, and blood pressure drops very low.

Drug toxicities and brain injuries can also lead to distributive shock.

Hypovolemic shock

Hypovolemic shock happens when there isn’t enough blood in your blood vessels to carry oxygen to your organs. This can be caused by severe blood loss, for example, from injuries.

Your blood delivers oxygen and vital nutrients to your organs. If you lose too much blood, your organs can’t function properly. Serious dehydration can also cause this type of shock.

How is shock diagnosed?

First responders and doctors often recognize shock by its external symptoms. They may also check for:

* low blood pressure
* weak pulse
* rapid heartbeat

Once they’ve diagnosed shock, their first priority is to provide lifesaving treatment to get blood circulating through the body as quickly as possible. This can be done by giving fluid, drugs, blood products, and supportive care. It won’t resolve unless they can find and treat the cause.

Once you’re stable, your doctor can try to diagnose the cause of shock. To do so, they may order one or more tests, such as imaging or blood tests.

Imaging tests

Your doctor may order imaging tests to check for injuries or damage to your internal tissues and organs, such as:

* bone fractures
* organ ruptures
* muscle or tendon tears
* abnormal growths

Such tests include:

* ultrasound
* X-ray
* CT scan
* MRI scan

Blood tests

Your doctor may use blood tests to look for signs of:

* significant blood loss
* infection in your blood
* drug or medication overdose

How is shock treated?

Shock can lead to unconsciousness, breathing problems, and even cardiac arrest:

* If you suspect that you’re experiencing shock, get medical help immediately.
* If you suspect that someone else has gone into shock, and provide first aid treatment until professional help arrives.

First aid treatment

If you suspect someone has gone into shock, call emergency. Then follow these steps:

* If they’re unconscious, check to see if they’re still breathing and have a heartbeat.
* If you don’t detect breathing or a heartbeat, begin CPR.

If they’re breathing:

* Lay them down on their back.
* Elevate their feet at least 12 inches above the ground. This position, known as the shock position, helps direct blood to their vital organs where it’s most needed.
* Cover them with a blanket or extra clothing to help keep them warm.
* Check their breathing and heart rate regularly for changes.

If you suspect the person has injured their head, neck, or back, avoid moving them.

Apply first aid to any visible wounds. If you suspect the person is experiencing an allergic reaction, ask them if they have an epinephrine auto-injector (EpiPen). People with severe allergies often carry this device.

It contains an easy-to-inject needle with a dose of hormone called epinephrine. You can use it to treat anaphylaxis.

If they begin to vomit, turn their head sideways. This helps prevent choking. If you suspect they’ve injured their neck or back, avoid turning their head. Instead, stabilize their neck and roll their entire body to the side to clear the vomit out.

Medical care

Your doctor’s treatment plan for shock will depend on the cause of your condition. Different types of shock are treated differently. For example, your doctor may use:

* epinephrine and other drugs to treat anaphylactic shock
* blood transfusion to replace lost blood and treat hypovolemic shock
* medications, heart surgery, or other interventions to treat cardiogenic shock
* antibiotics to treat septic shock

Can you fully recover from shock?

It’s possible to fully recover from shock. But if it isn’t treated quickly enough, shock can lead to permanent organ damage, disability, and even death. It’s critical to call 911 immediately if you suspect that you or someone you’re with is experiencing shock.

Your chances of recovery and long-term outlook depend on many factors, including:

* the cause of shock
* the length of time you were in shock
* the area and extent of organ damage that you sustained
* the treatment and care that you received
* your age and medical history

Can shock be prevented?

Some forms and cases of shock are preventable. Take steps to lead a safe and healthy lifestyle. For example:

* If you’ve been diagnosed with severe allergies, avoid your triggers, carry an epinephrine auto-injector, and use it at the first sign of an anaphylactic reaction.
* To lower your risk of blood loss from injuries, wear protective gear when taking part in contact sports, riding your bike, and using dangerous equipment. Wear a seatbelt when traveling in motor vehicles.
* To lower your chances of heart damage, eat a well-balanced diet, exercise regularly, and avoid smoking and secondhand smoke.

Stay hydrated by drinking plenty of fluids. This is especially important when you’re spending time in very hot or humid environments.

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It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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#1254 2022-01-14 17:39:33

ganesh
Administrator
Registered: 2005-06-28
Posts: 35,485

Re: Miscellany

1230) Glycerol

Glycerol,  also called glycerine in British English and glycerin in American English) is a simple polyol compound. It is a colorless, odorless, viscous liquid that is sweet-tasting and non-toxic. The glycerol backbone is found in lipids known as glycerides. Due to having antimicrobial and antiviral properties it is widely used in FDA (Food and Drug Administration) approved wound and burn treatments. Conversely, it is also used as a bacterial culture medium. It can be used as an effective marker to measure liver disease. It is also widely used as a sweetener in the food industry and as a humectant in pharmaceutical formulations. Owing to the presence of three hydroxyl groups, glycerol is miscible with water and is hygroscopic in nature.

Summary

Glyceroli is a clear, colourless, viscous, sweet-tasting liquid belonging to the alcohol family of organic compounds; molecular formula HOCH2CHOHCH2OH. Until 1948 all glycerol was obtained as a by-product in making soaps from animal and vegetable fats and oils, but industrial syntheses based on propylene or sugar has accounted for an increasingly large percentage of production since that time. The term glycerin (or glycerine), introduced in 1811 by French chemist Michel-Eugène Chevreul, is ordinarily applied to commercial materials containing more than 95 percent glycerol. Though Chevreul gave glycerin its name, the substance was first isolated in 1783 by German Swedish chemist Carl Wilhelm Scheele, who described it as the “sweet principle of fat.”

Glycerol has numerous uses. It is a basic ingredient in the gums and resins used to make many modern protective coatings such as automotive enamels and exterior house paints. Glycerin reacted with nitric and sulfuric acid forms the explosive nitroglycerin (or nitroglycerine).

Glycerol is also a component of mono- and diglyceride emulsifiers, which are used as softening agents in baked goods, plasticizers in shortening, and stabilizers in ice cream. Its varied uses in the pharmaceutical and toilet goods fields include skin lotions, mouthwashes, cough medicines, drug solvents, serums, vaccines, and suppositories. Another significant use is as a protective medium for freezing red blood cells, sperm cells, eye corneas, and other living tissues. At one time, its largest single use was as automotive antifreeze; methanol and ethylene glycol have replaced it for this purpose.

Fats and oils are valued chiefly as sources of the carboxylic acids that are present, combined in the form of esters with glycerol. When the acids are set free from these compounds, glycerol remains as a solution in water and is purified by coagulating and settling extraneous matter, evaporating the water, and distilling.

Glycerol which is also known as glycerine, glycerin or propanetriol is a polyol compound. The derivation of the gly- and glu- prefixes for glycerol and for sugars is derived from a Greek word glukus which means sweet.

It is a trihydroxy sugar alcohol which acts as an intermediate in carbohydrate and lipid metabolism. The formula of glycerol is C3H8O3.

PROPERTIES OF GLYCEROL

Glycerol is a colorless, odorless and viscous liquid which is sweet in taste and is non-toxic.

Boiling point: 290 degree Celsius, melting point: 17.9 degree Celsius.

Molecular weight: 92.094 g/mol, relative density: 1.261 g/ml.

Solubility: Insoluble in volatile oils and fixed oils, in water it is miscible.

Glycerol is weakly acidic in nature and is able to react with alkaline hydroxide.

PRODUCTION OF GLYCEROL

Natural production:

Glycerol is mostly obtained from plants and animal sources where it is present as triglycerides. Triglycerides are glycerol esters having carboxylic acids of a long chain. The hydrolysis, saponification or transesterification of these triglycerides gives out glycerol.

Plants sources typically include soybeans or palm trees. Another source is animal-derived tallow.

Synthetic production:

Glycerol can also be produced by various routes from propylene, which is a three carbon petrochemical compound with double bonds. The most important process is epichlorohydrin, which includes propylene chlorination giving allyl chloride, which is then oxidized with hypochlorite to dichlorohydrins, which gives epichlorohydrin by reacting with a strong base. Then this epichlorohydrin is then hydrolyzed to give glycerol.

Applications:

1. Food industry: Glycerol serves as a sweetener, solvent, and humectants in food and beverages and can also help in preserving food. It is also used in commercially prepared low-fat foods as filler and in liqueurs as a thickening agent. Glycerol is also used along with water to preserve certain types of leaves. It is also used as a sugar substitute.

2. Pharmaceutical and personal-care: Glycerol is utilized in pharmaceutical and personal care products preparations, majorly as a means of developing smoothness, for providing lubrication and as humectants. In tablets dosage, it is used a holding agent and it is also a component of glycerin soap. Glycerol is found in cough syrups, elixirs, toothpaste, mouthwashes, products of skin care and water-based personal care lubricants.

3. E-cigarette liquid: Vegetable glycerine with propylene glycol, in one of the common component of e-cigarette liquid. This glycerol produces the aerosol when heated with an atomizer, delivering nicotine to the consumer.

4. For anti-freezing: Glycerol was used as an anti-freezing agent for automotive applications in past before getting replaced by ethylene glycol. Glycerol is a common compound of solvents for enzymatic reagents in the labs. It is also used as a cryoproctectant.

5. Chemical intermediate: Glycerol is used in the production of nitroglycerin. Allyl iodide can be synthesized by utilization of elemental phosphorus and iodine on glycerol. Crude glycerol for a renewable energy source as an additive to biomass when burnt or gasified is being examined.

6. Film industry: When filming scenes which involve water to stop drying out of areas too quickly glycerol are used by the film industry.

Overview

Glycerol is a naturally occurring chemical. People use it as a medicine. Some uses and dosage forms have been approved by the U.S. Food and Drug Administration (FDA).

Glycerol is most commonly used for constipation, improving hydration and performance in athletes, and for certain skin conditions. It is also used for meningitis, stroke, obesity, ear infections, and other conditions, but there is no good scientific evidence to support these uses.

How does it work ?

Glycerol attracts water into the gut, softening stools and relieving constipation.

In the blood, it attracts water so that the water stays in the body longer. This might help an athlete exercise for longer.

Uses & Effectiveness ?

Likely Effective for

* Constipation. Giving glycerol into the rectum, as a suppository or as an enema, decreases constipation.

Possibly Effective for

* Athletic performance. There is some evidence that taking glycerol by mouth along with water helps to keep the body hydrated for longer. The increase in fluids in the body might help people exercise for a few minutes longer and possibly go a bit faster, especially if it is hot.
* Dandruff. Using a hair lotion containing glycerol, stearic acid, and sunflower seed oil 3 times each week can reduce dandruff by a small amount and moisturize the scalp.
* Dry skin. Applying a product containing glycerol and paraffin to the skin reduces the thickness of scales and itching in people with xerosis.
* An inherited skin disorder that causes dry, scaly skin (ichthyosis). Applying a specific, prescription-only product (Dexeryl, Pierre Fabre Laboratoires) containing glycerol and paraffin to the skin reduces symptoms like itching and scales in children with ichthyosis.

Possibly Ineffective for

* Swelling (inflammation) of membranes that protect the brain and spinal cord (meningitis). Taking glycerol along with medicines used to treat meningitis doesn't reduce the chance of death, seizures, or stomach and intestinal injury. But it might reduce the chance of deafness in children who survive the infection.
* Growth and development in premature infants. Giving glycerol into the rectum, as a suppository or as an enema, is sometimes used in premature infants to help them pass their first stool. It's thought that this will help them start to take food by mouth earlier. But glycerol doesn't seem to have much benefit for this purpose.

Likely Ineffective for

* Stroke. Receiving intravenous (IV) glycerol from a healthcare professional does not improve symptoms after a stroke.

Insufficient Evidence for

* Obesity. Early research in adults on a low-calorie diet shows that taking glycerol before meals does not increase weight loss.
* Swimmer's ear (otitis externa). Early research shows that having a doctor place a gauze soaked in ichthammol and glycerol into the ear canal reduces pain and swelling as much as using prescribed ear drops.
* Wrinkled skin.
* Other conditions.

More evidence is needed to rate glycerol for these uses.

Side Effects

* When taken by mouth: Glycerol is POSSIBLY SAFE when taken by mouth, short-term. Glycerol can cause side effects including headaches, dizziness, bloating, nausea, vomiting, thirst, and diarrhea.

* When applied to the skin: Glycerol is LIKELY SAFE when applied to the skin. When applied on the skin, glycerol might cause redness, itching, and burning.

* When given in the rectum: Glycerol is LIKELY SAFE when inserted into the rectum.

* When given by IV: Glycerol is POSSIBLY UNSAFE when injected intravenously (by IV). This might damage red blood cells.

Special Precautions and Warnings

* Pregnancy and breast-feeding: There isn't enough reliable information to know if glycerol is safe to use when pregnant or breast-feeding. Stay on the safe side and avoid use.

* Children: Glycerol is LIKELY SAFE when inserted into the rectum or applied to the skin in children at least 1 month old. Glycerol is POSSIBLY SAFE when taken by mouth, short-term in children 2 months to 16 years of age.

Dosing

The following doses have been studied in scientific research:

ADULTS

BY MOUTH:

* For athletic performance: Glycerol 1-1.5 grams/kg taken with about 6 cups of water starting an hour or two before competition. Glycerol is banned during competition in some sports because it might alter the amount of fluid in the blood and change the results of some laboratory tests.

ON THE SKIN:

* For dandruff: A leave-in hair lotion containing glycerol 10%, stearic acid 2.5%, and sunflower seed oil 0.6%, applied to the scalp 3 times weekly for 8 weeks.
* For dry skin: An emulsion containing glycerol 15% and paraffin 10% applied to the skin twice daily for 1-8 weeks.

RECTAL:

* For constipation: Glycerol 2-3 grams as a suppository or 5-15 mL as an enema.

CHILDREN

ON THE SKIN:

For an inherited skin disorder that causes dry, scaly skin (ichthyosis): A specific, prescription-only product (Dexeryl, Pierre Fabre Laboratoires) containing glycerol 15% and paraffin 10% applied to the skin for 4-12 weeks.

RECTAL:

* For constipation: For children younger than six years old, the dose is 1-1.7 grams as a suppository or 2-5 mL as an enema. For children older than six years of age, the dose is 2-3 grams as a suppository or 5-15 mL as an enema.

Additional Information

Molecular Weight : 92.09

Glycerol is a triol with a structure of propane substituted at positions 1, 2 and 3 by hydroxy groups. It has a role as an osmolyte, a solvent, a detergent, a human metabolite, an algal metabolite, a Saccharomyces cerevisiae metabolite, an Escherichia coli metabolite, a mouse metabolite and a geroprotector. It is an alditol and a triol.

Glycerin is a trihydroxyalcohol with localized osmotic diuretic and laxative effects. Glycerin elevates the blood plasma osmolality thereby extracting water from tissues into interstitial fluid and plasma. This agent also prevents water reabsorption in the proximal tubule in the kidney leading to an increase in water and sodium excretion and a reduction in blood volume. Administered rectally, glycerin exerts a hyperosmotic laxative effect by attracting water into the rectum, thereby relieving constipation. In addition, glycerin is used as a solvent, humectant and vehicle in various pharmaceutical preparations.

Glycerine appears as a colorless to brown colored liquid. Combustible but may require some effort to ignite.

Glycerol.jpg


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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#1255 Yesterday 16:42:05

ganesh
Administrator
Registered: 2005-06-28
Posts: 35,485

Re: Miscellany

1231) Maple

Summary

Acer is a genus of trees and shrubs commonly known as maples. The genus is placed in the family Sapindaceae. There are approximately 132 species, most of which are native to Asia, with a number also appearing in Europe, northern Africa, and North America. Only one species, Acer laurinum, extends to the Southern Hemisphere. The type species of the genus is the sycamore maple, Acer pseudoplatanus, the most common maple species in Europe. The maples usually have easily recognizable palmate leaves (Acer negundo is an exception) and distinctive winged fruits. The closest relatives of the maples are the horse chestnuts. Maple syrup is made from the sap of some maple species.

Details

Maple, (Acer), is any of a large genus (about 200 species) of shrubs or trees in the family Sapindaceae, widely distributed in the North Temperate Zone but concentrated in China. Maples constitute one of the most important groups of ornamentals for planting in lawns, along streets, and in parks. They offer a great variety of form, size, and foliage; many display striking autumn colour. Several yield maple syrup, and some provide valuable, dense hard wood for furniture and other uses. All maples bear pairs of winged seeds, called samaras or keys. The leaves are arranged oppositely on twigs. Many maples have lobed leaves, but a few have leaves separated into leaflets.

Among the popular smaller maples the hedge, or field, maple (A. campestre) and Amur, or ginnala, maple (A. ginnala) are useful in screens or hedges; both have spectacular foliage in fall, the former yellow and the latter pink to scarlet. The Japanese maple (A. palmatum), developed over centuries of breeding, provides numerous attractive cultivated varieties with varying leaf shapes and colours, many useful in small gardens. The vine maple (A. circinatum), of wide-spreading, shrubby habit, has purple and white spring flowers and brilliant fall foliage. The shrubby Siebold maple (A. sieboldianum) has seven- to nine-lobed leaves that turn red in fall.

Medium-sized maples, often more than 9 metres (30 feet) tall, include the big-toothed maple (A. grandidentatum); some believe it to be a subspecies of sugar maple, a Rocky Mountain tree, often multistemmed, displaying pink to red fall foliage. Coliseum maple (A. cappadocicum) and Miyabe maple (A. miyabei) provide golden-yellow fall colour. The three-flowered maple (A. triflorum) and the paperbark maple (A. griseum) have tripartite leaves and attractive peeling bark, in the former tannish and in the latter copper brown.

The ash-leaved maple, or box elder, is a fast-growing tree of limited landscape use. The Norway maple (A. platanoides), a handsome, dense, round-headed tree, has spectacular greenish-yellow flower clusters in early spring; many cultivated varieties are available with unusual leaf colour (red, maroon, bronze, or purple) and growth form (columnar, globular, or pyramidal).

Large maples, usually in excess of 30 metres high, that are much planted for shade include the sugar (A. saccharum), silver (A. saccharinum), and red (A. rubrum) maples. The Oregon, or bigleaf, maple (A. macrophyllum) provides commercially valuable wood darker than that of other maples; it shows bright-orange fall foliage. The Sycamore maple (A. pseudoplatanus), an important shade and timber tree in Europe, has many ornamental varieties.

In one group of maples, the vertically striped silvery-white young bark provides an attractive winter landscaping feature. These trees are the striped maple (A. pennsylvanicum), the red snake-bark maple (A. capillipes), the Her’s maple (A. hersii), and the David’s maple (A. davidii). The chalk maple, with whitish bark, is sometimes classified as A. leucoderme, although some authorities consider it a subspecies of sugar maple.

The parlour maples, or flowering maples, are bedding and houseplants in the genus Abutilon.

Additional Information

Maple trees belong to the genus Acer and family Sapindaceae. There are about 125 species of maple trees. They can be found growing parts of Asia, Europe, North America, Canada, and Northern Africa.

Maple trees are admired for their stunning display of fall leaf colors. The leaves turn into shades of yellow, orange, and red. This article is an in-depth look at the red maple, sugar maple, and silver maple trees.

Red Maple Tree

Red Maple Tree (Acer rubrum) is a deciduous tree well-known for its vibrant autumn leaves. This tree grows to a height of about 60 to 90 feet and has a trunk that can grow up to 30 inches in diameter. It is the state tree of Rhode Island.

These trees can adapt well to different soil and climate conditions. The red maple tree grows short taproots with long lateral roots in wet soil and develops deep taproots with short lateral roots in dry soil.

The crown has a spread of 25 to 35 feet and is rounded, or oval when it reaches maturity. The young trees have smooth light gray bark that becomes a darker gray furrowed and scaly at maturity. The average lifespan of the red maple is 80 to 100 years. They start producing seeds when they are four years old.

The leaves of the red maple are palmate, 3 inches to 6 inches wide, and have 3 to 5 lobes. They are green above and pale green below. The margins are serrated with shallow "V "shaped divisions between lobes.

The leaves turn to shades of yellow, orange-red to bright red during fall. They are highly serrated when compared to the sugar maple leaves.

The flowers of the red maple are bright red and are found growing in clusters. They appear in spring before the leaves unfurl. A single red maple tree can produce all male flowers, all-female flowers, or both male and female flowers on the same tree. Some maple trees are monoecious having the male and female gender organs in the same flower. The male flowers have long stamens that extend beyond the petal with yellow pollen at the tips. In the female flower, the stigma extends beyond the petals to catch the pollen.

The fruit of the red maple tree produces winged samaras (winged seeds). They are known as spinners because they spin as they fall to the ground.

The red maple samaras are red, whereas those of the sugar maple is green in spring. These samaras disperse in spring before the leaves are fully developed. The sugar maple samaras hang on without dispersing until the fall.

Uses of Red Maple

Due to its bright red colored leaves, fruits, and beautiful fall colors, the red maple tree is valued as an ornamental tree. Wood of the red maple tree is ideal for the manufacture of boxes and musical instruments.

Red Maple and Wildlife

Red maple is a source of food for moose, deer, and rabbits. The sap has half the sugar content of the sugar maple tree, but it has a great taste.

The seeds, the buds, and flowers are food for many wildlife species. Wood ducks nest inside cavities of red maples.

Sugar Maple Tree

The sugar maple (Acer saccharaum) belongs to the soapberry family (Sapindaceae). The sugar maple tree is a deciduous tree that grows to a height of 60 feet to 80 feet and has a diameter of 1 to 2 feet. The sugar maple is also called hard maple because of the density and strength of its wood.

The bark of the young sugar maple tree is brownish gray. As they grow older, the bark becomes darker, furrowed with thin, gray scaly plates. The crown of the sugar maple is dense and has an oval, rounded or a columnar shape. This tree is planted as a shade tree because of its dense crown.

The sugar maple has a shallow root system with strong lateral roots that are highly branched.

The leaves of the sugar maple tree are borne on a smooth stalk. They are palmate and measure three to five inches in width and height. They have five lobes with serrated margins. The division between the lobes is smooth, shallow and rounded. The leaves turn into colors of yellow, orange and deep red during fall.

The two lobes at the base of the leaves are smaller than the other three and are almost parallel to each other.

A sugar maple tree can produce all-male flowers or all female flowers or both on the same tree. Some trees bear flowers that have both the male and female gender organs. The flowers of the sugar maple are found in clusters and are greenish-yellow. They appear in spring just before the leaves emerge.

The fruits of this tree are double samaras (winged seeds) that are green in spring and turn yellowish-green or light brown in autumn.

Maple syrup is made from the sap of the sugar maple tree. It takes about 40 gallons of sap to make one gallon of maple syrup.

Uses of Sugar Maple

Sugar maple has heavy, strong wood that is used to make furniture, paneling, flooring, and veneer. It is also used to make bowling pins and musical instruments. The maple tree wood is a tonewood (wood that carries soundwaves, due to this property the maple wood is used to make musical instruments like violins, violas, and cellos. The necks of electric guitars are also made from maple wood.

Sugar Maple and Wildlife

Sugar maple is a source of food for many wildlife species. The white-tailed deer, moose and snow hares browse on sugar maple trees. Red squirrels feed on its buds, twigs, and leaves. Porcupines eat the bark.

The flowers are wind-pollinated. The pollen that is initially produced is essential for Apis mellifera (honey bees) and other insects. The sugar maple is a caterpillar host for the Cecropia Silkmoth and Rose Maple Moth. Many birds build nests and forage the tree for insects.

Silver Maple Tree

Silver Maple (Acer saccharinum) is also called soft maple or white maple. It is a deciduous tree that has rapid growth with a shallow root system. It belongs to the soapberry family (Sapindaceae) and has a stout trunk with large forked spreading branches. The branches are brittle and break easily.

This tree grows to a height of about 60 to 120 feet. The young bark is smooth and gray but becomes flaky as it reaches maturity. The crown of the maple tree is vase-shaped with an irregular crown.

The leaves are 4 to 6 inches long, green above, silvery below, and have five lobes with deep "V" shaped divisions. The middle lobe is also divided into three lobes with shallow sinuses. The twigs are slender, red-brown, and curved upwards. The leaves turn yellow to red during fall.

The silver maple tree is monoecious. The male flowers are greenish-yellow, and the female flowers are red. They appear in clusters in early spring before the leaves begin to unfold.

The fruits of the silver maple are samaras that grow in attached pairs with green or yellow wings with large seeds at the base. They measure about 1.2 - 2 inches in length and are the largest samaras among all maple trees.

The silver maple trees are not favored for landscaping because of its brittle wood that breaks off during storms. The roots are shallow, grow rapidly, and can cause cracks in basement walls, sidewalks, tanks, and drain pipes.

The cut-leaf silver maple (A.saccharinum ‘Laciniatum’) and the pyramidal silver maple (A.saccharinum ‘Pyramidale’) varieties are used in landscaping because they are not very tall and have sturdy branches.

Silver maples have thin, watery sap with low sugar content and hence not ideal for making maple syrup.

Uses of Silver Maple

The wood of silver maple is used to make lightweight furniture, cabinetry, paneling, flooring, veneer, musical instruments, boxes, crates, and tools.

Silver Maple and Wildlife

The seeds of the silver maple tree are eaten by many birds, squirrels, and chipmunks. The buds are a source of food for squirrels during late winter and early spring. The bark is food for beavers and the leaves are eaten by deer and rabbits. The silver maple tree tends to form cavities that are used for shelter by nesting birds and mammals.

Maple Syrup Extraction

Maple is a sweet syrup that is obtained from the sap of the maple tree. Any tree that is eight inches or more in width can be tapped for maple syrup.

From the beginning of the 17th century, dairy farmers were looking for a source of sweetener that was better in quality and cheaper than sugar. They drilled holes in the trees during the short time between winter and spring.

The farmers hung buckets under the drilled holes. They called the maples tree “sugar bushes”. After a day or two, the farmers would empty the buckets in large containers and haul the sap to a sugar house built in the woods. To make the brown, sweet maple syrup the sugar manufacturers boiled the sap to remove most of the water content.

Nowadays holes are bored in sugar maples in early spring. Small plastic spouts are inserted into these holes and the spouts are connected to a central plastic tubing that allows the sap to flow into large tanks.

The sap from the maple tree oozes out when the day temperature is forty degrees followed by a night when the temperature is below freezing. Global warming has affected the production of maple syrup resulting in a substantial increase in the price of maple syrup.

maple-leaf-300x300.png


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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