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Showing posts from June, 2020

LORD OF THE RINGS

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Saturn is perhaps the most beautiful of the planets of the Solar System. It has fascinated astronomers because of the mysterious rings. The Pioneer, Voyager and Cassini-Huygens space-probes sent back a great deal of information on the nature of the rings and the mass of Saturn itself.        Each ring is made up of a stream of icy particles, following each other nose-to-tail around the planet. The particles an be of widely varying sizes. The rings resemble a snowstorm are mixed with snowballs up to the size of house. The ice that surrounds one of the most spectacular planets of our solar system is made off water - the same substance (with the same formula) that covers so much of the Earth's surface.        The planet of Saturn is made of gases, mainly hydrogen and helium. Deep in the centre of these lightweight gases is a small rocky core, surrounded by a liquid layer of the gases. The hydrogen is liquid because of the high pressure in the inner r...

A CONTROVERSIAL LIFE IN SCIENCE

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                                       Fritz Haber is one of Germany's most famous chemists. He is also one of the most complex figures in the history of science whose life and career were intricately linked with the political struggles and turmoil in Europe that led to two world wars.         Working at the University of Karlsruhe in the 1890s, he devised a method for the  direct synthesis of ammonia from nitrogen and hydrogen, using high pressure and temperature together with an osmium catalyst. In 1918, Haber received the Nobel Prize in Chemistry for his work on the process.         Continuing his research, Haber developed a process for converting ammonia into nitric acid, which was then used as the basis for producing nitrate high explosives. This significantly helped the German effort in the First World War (1914-18) and Haber became ...

PROPERTIES OF ENZYMES

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 All enzymes are proteins : This may seem rather odd, because some enzymes actually digest proteins. Enzymes are made inactive by high temperature :   This is because they are protein molecules, which are damaged by heat. Enzymes work best at particular temperature :   Enzymes which are found in the human body usually work best at about 37˙C.  Enzymes work best at a particular pH :  pHis a measure of how acid or alkaline a solution is. Some enzymes work best in acid conditions (low pH). Others work best in neutral or alkaline conditions (high pH). Enzymes are catalysts : They are not changed in the chemical reactions which they control. They can used over and over again, so a small amount of enzyme can change a lot of substrate into product. Enzymes are specific : This means that each kind pf enzymes will only catalyse one kind of chemical reaction.

LYMPH

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                                                   The plasma and white cells that leak out of the blood capillaries must eventually be returned to the blood. In the tissues, as well as blood capillaries, are other small vessels. They are lymphatic capillaries. The tissue fluid slowly drains into them. The fluid s now called lymph .          The lymphatic capillaries gradually join up to form larger lymphatic vessels. They carry the lymph to the subclavian veins which bring blood back from the arms. Here the lymph enters the blood again.          The lymphatic system has no pump to make the lymph flow. Lymph vessels do have valves in them, however, to make sure that movement is only in one direction. Lymph flows much more slowly than blood. Many of the larger lymph vessels run within or very close to muscles, ...