A small amount of air is trapped and pressurized when the fixed end of the thumb and the free end of the middle finger are brought together. When this pressurized air is released suddenly during the clicking it produces a sound as in the case of a balloon burst.
Sound is caused by the cracking of knuckles when a bubble which has formed in the lubricating fluid (the synovial fluid) which surrounds the two bones of the knuckles bursts.
Normally there is a lubricating fluid which prevents the two bones which forms the knuckles from grating against each other. This fluid contains tiny bubbles which cannot be seen by the naked eye.
So when the knuckle bones remain close together the fluid is under pressure and the bubbles remain tiny.
But when one clenches his fist, the bones are pulled apart which causes the bubbles to join together to form one large bubble. Then when one works the fist, the pressure changes and makes the bubble to burst which then produces a loud cracking, noise. Doctors are not sure whether cracking them is harmful or not, though there is a belief that cracking ones knuckles could make them large and unsightly.
TFM is the abbreviated form of ‘Total Fat Matter’ in soap. According to the provisions of the Drugs and Cosmetic Rules, in all toilet soaps, the TFM content has to be mentioned in terms of percentage on the wrapper of the product apart from the other details required under the rules.
The standard fixed by the Bureau of Indian Standard (formerly I.S.I.), the ideal and safe percentage of TFM in any toiletry preparation should be between 60 and 80 per cent.
However, having been unsure of the standard, even many of the reputed soap manufacturers have omitted ‘toilet soap’ from their name and simply state ‘bathing bar’. Similarly shaving soaps are marketed as showing creams without mention of TFM content.
Water boils at 100°C at sea level. The atmospheric pressure which acts on water is 14.7 psia (pounds per square inch –absolute). This atmospheric pressure varies with the altitude. So the boiling point of water is influenced with respect to the atmospheric pressure. Perfect vacuum is ‘O’ psia.
Any pressure between 14.7 psia and o-psia is ‘negative pressure’ that is, partial vacuum.
Vacuum drying takes advantage of the decrease in the boiling point of water that occurs as the pressure is lowered. This type of drying keeps the products with very low moisture content. If salt water is subjected to this negative pressure, the water will boil by taking the heat from the ambient. In case of reducing atmospheric pressure, i.e. 14.7 psia to 0.15 psia, water will start boiling at C itself.
Freeze drying, convection drying, microwave drying, dielectric drying, conduction drying, U-V radiation drying, etc, are some other drying methods applied in various industries such as textile, plywood manufacturing, paper products, production of dried milk, soaps, detergents, pharmaceuticals, serums, bacterial and viral cultures, vaccines, fruit juices, vegetables, coffee and tea extracts, sea foods, meats, cereals etc.
Trains are generally equipped with vacuum brakes. In steam locomotives, ejectors help create the vacuum and in diesel and electric locomotives, air-compressors and vacuum exhausters are used.
Pipes passing through the underside of coaches are connected to vacuum cylinders (provided in the coach) which help maintain a vacuum throughout the length of the pipe. The pipes (of each coach) are then linked.
When the train is on the run, a vacuum of about 20-22 inches per square inch is maintained throughout the system (atmospheric pressure is 30 pounds per square inch).
When the driver wants to stop the train, he gradually allows air to enter the vacuum pipe and activates the pistons of the vacuum cylinders which help to apply the brake.
For emergency application of brakes by passengers, coaches are provided with alarm chains connected to the vacuum system. When the chain is pulled, a small valve open up and allows air to enter the system slowly, gradual application of the brakes.
Direct admission valves are provided in each coach near the vacuum cylinder and they help in the uniform application of the brake throughout the train.
Anything that is formed without the act of fertilization is biologically called “vegetative”. The term “vegetative” is more appropriate to the plants but not for animals. But it has become customary to term the unfertilized eggs of hens as vegetarian eggs since they are formed without the fusion of sperm.
Country breed birds lay fertilized eggs. Such eggs are laid a week or more after the cock has mated the hens, but white leghorns which are suitable for egg production lay only unfertilized eggs as they are not allowed to mate with cocks. The leghorns are genetically improved birds which produce through successive generations under improved breeding methods.
Nutritionally there is no difference between a vegetarian egg and an ordinary egg, but in certain physiological characteristics they differ. Leghorn eggs cannot be incubated, but eggs of country breed can be incubated. Such hatching eggs deteriorate with storage and therefore should not be stored beyond seven days, while leghorn eggs can be stored for several days.
The eggs of poultry bred leghorn birds are larger in size, with more amount of albumin and always white in colour. The eggs of country bred birds are smaller in size and have less amount of albumin and the shell colour may vary from white to pale straw yellow colour. The natural feeding habit of these birds is the only reason for these characteristics.
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