VITAMINS

 

VITAMINS

The word “vitamin” goes back to the Polish scientist Casimir Funk in 1912.  He was studying a substance in the layer that covers rice.  This substance was believed to cure a disease called beriberi.

Funk believed the substance belonged to a group of chemicals known as amines.  He added the Latin word "vita," meaning life.  So he called the substance a “vitamine” -- an amine necessary for life.

Scientists have discovered fourteen kinds of vitamins.  They are known as vitamins A, the B group, C, D, E and K.  Scientists say vitamins help to carry out chemical changes in cells.  If we do not get enough of the vitamins we need in our food, we may develop a number of diseases. 

This brings us back to Casmir Funk.  His studies of rice were part of a long search for foods that could cure disease.

One of the first people involved in that search was James Lind of Scotland.  In the 1740s, Lind was a doctor for the British navy.  He investigated a problem that had existed in the navy for many years. 

The problem was the disease scurvy.  So many sailors had scurvy that the navy’s lost some of its strength.  The sailors were weak from bleeding inside their bodies.  Even the smallest wound would not heal.  Doctor Lind thought the sailors were getting sick because they failed to eat some kinds of foods when they were at sea for many months.

Doctor Lind separated twelve sailors who had scurvy into two groups.  He gave each group different foods to eat.  One group got oranges and lemons.  The other did not.  The men who ate the fruit began to improve within seven days.  The other men got weaker.  Doctor Lind was correct.  Eating citrus fruits prevents scurvy.

Types of Vitamins

Vitamin A helps prevent skin and other tissues from becoming dry.  It is also needed to make a light-sensitive substance in the eyes.  People who do not get enough vitamin A cannot see well in darkness.  Their eys may get dry.  This can result in infections and lead to blindness.

Vitamin A is found in fish liver oil.  It also is in the yellow part of eggs.  Sweet potatoes, carrots and other darkly colored fruits and vegetables contain substances that the body can change into vitamin A. 

Vitamin B-one is also called thiamine.  Thiamine changes starchy foods into energy.  It also helps the heart and nervous system work well.  Without it, we would be weak and would not grow.  We also might develop beriberi. Apart from rice thiamine is found in beans , peas, nuts, meat and fish.

Another B-vitamin is niacin.  It helps cells use food energy.  It also prevents pellagra -a disease that causes weakness, reddish skin and stomach problems.  Niacin is found in meat, fish and green vegetables.

Vitamin B-12 helps produce red blood cells.  It is found naturally in foods such as eggs, meat, fish and milk products.  It also helps babies of pregnant mothers before they are born .  Vitamin B-12 is found in green leafy vegetables and other foods and citrus fruits.  In some countries, it is added to products like bread.

Vitamin C is needed for strong bones and teeth, and for healthy blood.  It also helps wounds heal quickly.  Because our body stores little vitamin C we must get it every day in foods such as citrus fruits, tomatoes and cabbage.

Vitamin D helps make calcium in the blood.  Calcium is needed for nerve and muscle cells to work normally.  It also is needed to build strong bones.  Ultraviolet light from the sun changes a substance in the skin into vitamin D.  Fish liver oil also contains vitamin D.  In some countries, milk producers add vitamin D to milk so children will get enough.

Vitamin K is needed for healthy blood.  It thickens the blood around a cut to stop bleeding.  Bacteria in the intestines normally produce vitamin K.  It can also be found in pork products, liver and in vegetables like cabbage, and spinach.

Some people fear they do not get enough vitamins from the foods they eat.  So they take products with large amounts of vitamins.  They think these products or vitamin supplements will improve their health and protect them from disease.

Experts note that taking too much of some vitamins can be harmful.  People should be sure to discuss what vitamins they take with their doctors.  This is because some vitamins can cause harmful effects when mixed with medicines.

Coffee - a Popular Hot Drink

   Coffee - a Popular Hot Drink

Coffee is one of the most popular hot drinks in the world. Almost a third of the world’s population drinks coffee.  People often meet at cafes or coffee shops for a coffee break during the middle of the morning or stop work in the afternoon to drink coffee.

About 7 million tons of coffee are produced every year. Brazil is, by far, the world’s largest coffee producer. About a third of the world’s production comes from this South American country. Other coffee producing countries include Vietnam, Indonesia and Columbia.

The United States is the biggest coffee consumer in the world. About 1.2 billion kilograms of coffee are consumed there every year. Drinking coffee is extremely popular in European countries, like Italy, France and Germany, as well as in Brazil.

The coffee plant

Coffee grows as a green-leaved tree or bush with blossoming white flowers. The coffee shrub originally comes from Ethiopia but, in the course of time spread to Southeast Asia and South America.

There are two basic types of coffee. Arabica accounts for about 70% of the world’s coffee production. It is grown in the higher regions of central and South America and is popular for its flavor and fragrance. Robusta has spread throughout central and eastern Africa. Although it makes up only thirty per cent of the total coffee production it has become more important because it can resist diseases better. It also has smaller beans and can grow at lower altitudes than Arabica.

Coffee plants grow in the warm and moist climate of the tropics and subtropics. Most coffee trees grow best between 1000 and 2500 meters above sea level.

Coffee trees produce fruits called berries. At first they are yellow, and then become red as they mature. An average coffee tree can produce enough berries to make about a pound (half a kilo) of roasted coffee.

Coffee seeds are grown in nursery beds. After a year they are planted in specially prepared fields. It takes a coffee tree about six years to produce a full harvest of coffee berries.  The largest ones can get up to six meters tall, but they are normally trimmed to a height of 1.5 to 4 meters.

Harvesting and processing coffee

Most coffee berries are picked by hand, which makes sure that only the good berries are used. After separating berries from leaves and other waste materials, the beans are then taken out, cleaned and dried. Only the best beans make it to the market. Then they are put into bags and shipped to countries where they are roasted.

At their destination the beans are combined to make different blends of coffee. Roasting for about 15 minutes brings out the true flavor of the coffee. The roasted coffee beans are packaged; some of them are crushed to ground coffee.

Effects of coffee

Coffee contains caffeine, a substance that stimulates parts of the body, especially heart and muscles. People often drink coffee to help them stay awake or keep them alert. Although coffee has some negative effects it is not thought to be a harmful drink. Children and people who have heart problems should not drink coffee it in great quantities. In decaffeinated coffee the caffeine is extracted in a chemical process.

How coffee is brewed.

Coffee must be ground before it is brewed. Grounding usually takes place inside a coffee machine, but you can also buy ground coffee in shops. The simplest brewing process is pouring boiling water over a filter of ground coffee and letting it flow into a pot. Coffee is often made by using simple machines that force hot water through a pad of pressed coffee. Espresso machines press hot water through ground coffee.

Instant coffee is made by pouring hot water over powdery coffee. It dissolves at once and you do not need a special machine.

History of coffee

Coffee originated in the east African highlands in the 6th century. It was then brought to Arabia where people used it as food and medicine. During the 11th century the first coffee drinks came up. In the 16th and 17th centuries coffee became widely popular in Europe when the Turks brought it to Central Europe. In the 17th and 18th century coffee conquered North and South Amercia.

Coffee houses soon became popular all over the world. In the 1900s chains of coffee shops developed in Europe and America. Today, Starbucks is the largest coffeehouse chain in the world, with over 20,000 stores in 60 countries.

Types of Coffee drinks

Espresso is probably the most popular coffee drink in the world. It is made by forcing hot water through a pad filled with dark ground coffee. Although there is not much coffee in the cup an espresso is very strong. It is usually drunk black, with no milk added.

Americano is an espresso with hot water added to make it weaker.

Café Latte is an espresso with a lot of hot milk and foam added on the top.

Cappuccino is a cup of espresso, together with warm milk and a lot of milk foam at the top. In some coffee shops it is decorated with flaked chocolate or cocoa.

Cafe Mocha is a cappuccino with chocolate or cocoa added.

Frappe is a cold espresso  that you can get at some coffee shops during the hot summer months.

Turkish coffee is usually thicker than normal coffee. It is made by combining  ground coffee and water to a muddy mixture.

Chocolate - History and Production

 Chocolate - History and Production

Chocolate is a food that is popular all over the world. It is made from the seeds of the cacao tree. It can be eaten and also used as a flavour in ice cream, candy and other foods. Many people like the taste of chocolate and those who work hard eat it to give them energy.

History of chocolate

Chocolate originally came from Mexico and Central America. Historians think that the Maya took the wild cacao trees from the rainforest and planted them in their own gardens. They crushed the seeds and mixed them with water and spices to make a hot drink.

Chocolate and cacao were very important for the Mayan culture. Families drank a hot chocolate drink at special occasions and at parties.

The Aztecs, a people who lived centuries later, used cacao beans as a form of money. They traded other valuable goods to get them because they didn’t grow there. Only the rich people had the money to buy cacao and drink hot chocolate.

In the 16th century Spanish explorers brought cacao back to Europe, where the drink became popular quickly, especially among kings, queens and noblemen. Other European powers began to plant cacao trees in their own colonies.

During the Industrial Revolution new technologies were able to make the production of cacao cheaper, so that poorer people could also afford it. In the 19th century the beans were pressed together with butter and mixed with sugar into a new form, chocolate.

Today the biggest chocolate producing countries are the United States, Great Britain, Germany, Switzerland, the Netherlands and France.

How cacao grows

Cacao trees grow in the tropical regions of South America, Africa and Asia. The biggest cacao bean producers are the Ivory Coast, Ghana, Indonesia and Brazil. The cacao tree can grow to a height of 7 metres. After about 5 years the cacao trees produce large fruits. When the fruit is ripe it can contain 20 to 40 seeds.

How chocolate is made

After the cacao seeds are harvested they are transported to factories, where they are cleaned and dried. The outer parts of the seeds are removed.

Workers then roast the beans to give them a certain flavour. The seeds of the cacao beans have a lot of fat in them. They are grinded and mixed together with butter to form cocoa butter.

A dry powder can be made by pressing fat and water out of the cocoa butter. This powder is used for baking and also mixed with hot milk to drink.

Chocolate bars are made by putting sugar and milk into the cocoa butter. This paste is then put into different kinds of moulds.

Chocolate making is a big business. More than five billion dollars worth of cacao beans are sold every year. Americans, for example, eat five kilograms of chocolate every year.

Value of Chocolate

Chocolate has a lot of calories but it also has carbohydrates, fats, and other vitamins and minerals. It can give you a lot of energy that you need to do sports or hard work.

Scientists have found out that eating chocolate reduces blood pressure and the risk of heart disease and cancer.

There are also negative effects of chocolate. It can make you addicted and lead to obesity. Chocolate in large amounts lead to tooth decay.

Carbon dioxide

 Carbon dioxide

Carbon dioxide is a compound in which two oxygen atoms are connected to a carbon atom. At normal temperatures it is a colourless gas that exists naturally in the Earth’s atmosphere. The air that we breathe has about 0.03% of carbon dioxide in it.

Carbon dioxide is an important part of the carbon cycle and essential for life on Earth.  Without it temperatures on our planet would be very low.

Plants use the sunlight and take up the CO2 in the atmosphere to produce energy and oxygen. This process is called photosynthesis.

The gas is also produced when fossil fuels are burned. Carbon dioxide that has been stored for millions of years in coal, oil and natural gas is set free. Living creatures produce carbon dioxide when they breathe out. It is emitted from volcanoes and hot springs. Deforestation sets carbon that is stored in trees free.

Carbon dioxide is an important greenhouse gas. Light that enters the atmosphere it is converted to heat. Higher amounts of CO2 make the atmosphere denser and keep it from getting out. CO2 is a gas that is highly responsible for global warming. Since the Industrial Revolution of the 1800s the amount of CO2 in our atmosphere has risen by 40%.

Throughout the centuries carbon dioxide has been in balance. Now more carbon dioxide is being produced than can be absorbed by nature.

Uses of Carbon Dioxide

Carbon dioxide is used in various industries to produce food, chemicals and oil products. It is especially common as a food additive and is added to beverages to give fizz to sparkling wine and water. It is also responsible for a beer’s foam.

As a pressurized gas carbon dioxide is used in fire extinguishers because it does not burn. Put in cartridges it can be used to inflate bike tires. In its solid form CO2 is called dry ice. It is used for cooling fresh food or ice cream. Liquid carbon dioxide is needed to remove caffeine from coffee.

Carbon dioxide in oceans

Oceans are carbon sinks. They absorb more than 25% of all the carbon dioxide that people emit into the atmosphere. As a result, the ocean’s water is becoming more acidic. This change affects the food chain and all sea organisms.

Carbon dioxide poisoning

Although carbon dioxide is not poisonous in normal amounts it can kill you if there is more than 10% in the air. High concentrations can lead to dizziness, bad sight, breathing problems as well as a high blood pressure and an increased heart beat. High levels of CO2 occur when there is not enough fresh air in a room.

 

What is ACID RAIN?

                                             https://www.youtube.com/watch?v=3uzWUQlZvm0

Louis Pasteur

 

Louis Pasteur

Louis Pasteur, (born December 27, 1822, Dole, France—died September 28, 1895, Saint-Cloud), French chemist and microbiologist who was one of the most important founders of medical microbiology. Pasteur’s contributions to science, technology, and medicine are nearly without precedent. He pioneered the study of molecular asymmetry; discovered that microorganisms cause fermentation and disease; originated the process of pasteurization; saved the beer, wine, and silk industries in France; and developed vaccines against anthrax and rabies.

Pasteur’s academic positions were numerous, and his scientific accomplishments earned him France’s highest decoration, the Legion of Honour, as well as election to the Académie des Sciences and many other distinctions. Today there are some 30 institutes and an impressive number of hospitals, schools, buildings, and streets that bear his name—a set of honours bestowed on few scientists.

Early education

Pasteur’s father, Jean-Joseph Pasteur, was a tanner and a sergeant major decorated with the Legion of Honour during the Napoleonic Wars. This fact probably instilled in the younger Pasteur the strong patriotism that later was a defining element of his character. Louis Pasteur was an average student in his early years, but he was gifted in drawing and painting. His pastels and portraits of his parents and friends, made when he was 15, were later kept in the museum of the Pasteur Institute in Paris. After attending primary school in Arbois, where his family had moved, and secondary school in nearby Besançon, he earned his bachelor of arts degree (1840) and bachelor of science degree (1842) at the Royal College of Besançon.

Research career of Louis Pasteur

In 1843 Pasteur was admitted to the École Normale Supérieure (a teachers’ college in Paris), where he attended lectures by French chemist Jean-Baptiste-André Dumas and became Dumas’s teaching assistant. Pasteur obtained his master of science degree in 1845 and then acquired an advanced degree in physical sciences. He later earned his doctorate in sciences in 1847. Pasteur was appointed professor of physics at the Dijon Lycée (secondary school) in 1848 but shortly thereafter accepted a position as professor of chemistry at the University of Strasbourg. On May 29, 1849, he married Marie Laurent, the daughter of the rector of the university. The couple had five children; however, only two survived childhood.

Germ theory of fermentation

In 1854 Pasteur was appointed professor of chemistry and dean of the science faculty at the University of Lille. While working at Lille, he was asked to help solve problems related to alcohol production at a local distillery, and thus he began a series of studies on alcoholic fermentation. His work on these problems led to his involvement in tackling a variety of other practical and economic problems involving fermentation. His efforts proved successful in unraveling most of these problems, and new theoretical implications emerged from his work. Pasteur investigated a broad range of aspects of fermentation, including the production of compounds such as lactic acid that are responsible for the souring of milk. He also studied butyric acid fermentation.

In 1857 Pasteur left Lille and returned to Paris, having been appointed manager and director of scientific studies at the École Normale Supérieure. That same year he presented experimental evidence for the participation of living organisms in all fermentative processes and showed that a specific organism was associated with each particular fermentation. This evidence gave rise to the germ theory of fermentation.

Inorganic chemistry

 

Inorganic chemistry

        Modern chemistry, which dates more or less from the acceptance of the law of conservation of mass in the late 18th century, focused initially on those substances that were not associated with living organisms. Study of such substances, which normally have little or no carbon, constitutes the discipline of inorganic chemistry. Early work sought to identify the simple substances—namely, the elements—that are the constituents of all more complex substances. Some elements, such as gold and carbon, have been known since antiquity, and many others were discovered and studied throughout the 19th and early 20th centuries. Today, more than 100 are known. The study of such simple inorganic compounds as sodium chloride (common salt) has led to some of the fundamental concepts of modern chemistry, the law of definite proportions providing one notable example. This law states that for most pure chemical substances the constituent elements are always present in fixed proportions by mass (e.g., every 100 grams of salt contains 39.3 grams of sodium and 60.7 grams of chlorine). The crystalline form of salt, known as halite, consists of intermingled sodium and chlorine atoms, one sodium atom for each one of chlorine. Such a compound, formed solely by the combination of two elements, is known as a binary compound. Binary compounds are very common in inorganic chemistry, and they exhibit little structural variety. For this reason, the number of inorganic compounds is limited in spite of the large number of elements that may react with each other. If three or more elements are combined in a substance, the structural possibilities become greater.

         After a period of quiescence in the early part of the 20th century, inorganic chemistry has again become an exciting area of research. Compounds of boron and hydrogen, known as boranes, have unique structural features that forced a change in thinking about the architecture of inorganic molecules. Some inorganic substances have structural features long believed to occur only in carbon compounds, and a few inorganic polymers have even been produced. Ceramics are materials composed of inorganic elements combined with oxygen. For centuries ceramic objects have been made by strongly heating a vessel formed from a paste of powdered minerals. Although ceramics are quite hard and stable at very high temperatures, they are usually brittle. Currently, new ceramics strong enough to be used as turbine blades in jet engines are being manufactured. There is hope that ceramics will one day replace steel in components of internal-combustion engines. In 1987 a ceramic containing yttrium, barium, copper, and oxygen, with the approximate formula YBa2Cu3O7, was found to be a superconductor at a temperature of about 100 K. A superconductor offers no resistance to the passage of an electrical current, and this new type of ceramic could very well find wide use in electrical and magnetic applications. A superconducting ceramic is so simple to make that it can be prepared in a high school laboratory. Its discovery illustrates the unpredictability of chemistry, for fundamental discoveries can still be made with simple equipment and inexpensive materials.

         Many of the most interesting developments in inorganic chemistry bridge the gap with other disciplines. Organometallic chemistry investigates compounds that contain inorganic elements combined with carbon-rich units. Many organometallic compounds play an important role in industrial chemistry as catalysts, which are substances that are able to accelerate the rate of a reaction even when present in only very small amounts. Some success has been achieved in the use of such catalysts for converting natural gas to related but more useful chemical substances. Chemists also have created large inorganic molecules that contain a core of metal atoms, such as platinum, surrounded by a shell of different chemical units. Some of these compounds, referred to as metal clusters, have characteristics of metals, while others react in ways similar to biologic systems. Trace amounts of metals in biologic systems are essential for processes such as respiration, nerve function, and cell metabolism. Processes of this kind form the object of study of bioinorganic chemistry. Although organic molecules were once thought to be the distinguishing chemical feature of living creatures, it is now known that inorganic chemistry plays a vital role as well.