Category Applied Science & Technology

Eggs are egg-shaped for several reasons. First, it enables them to fit more snugly together in the nest, with smaller air spaces between them. This reduces heat loss and allows best use of the nest space.

 Second, if the eggs roll, it will roll in a circular path around the pointed end. This will reduce the danger of the egg rolling out of the nest. Moreover le strongest shape would be a sphere, but spherical eggs will roll away, and this will be unfortunate, for birds that nest on cliffs.

Most eggs will roll in a curved path, coming to rest with the sharper end pointing uphill.

There is in fact a noticeable tendency for the eggs of cliff-nesting birds to deviate more from the spherical, and thus roll in a tighter arc.

Third, an egg shape is more comfortable for the bird while it is lying, rather than a sphere or a cylinder. Other shapes have structurally weak points and edges. Finally, another important reason is that hen’s eggs are the ideal shape for fitting into egg cups and egg holders on the fridge door. No other shape would do.

Food poisoning is caused either by ingestion of food contaminated with chemical or metallic poisons, bacteria or bacterial toxins or by eating poisonous foods such as certain species of mushrooms.

Molds and bacteria are responsible for microbial food poisoning. Molds grow on food (especially if they are moist). During their growing period they produce toxic substances called mycotoxins whose effect on man and animals cause mycotoxicosis. Mycotoxins remain the food long after the mold producing them has died and can therefore be present in foods that are not visibly moldy. Some mycotoxins are stable and survive the usual conditions of cooking and processing.

Food grains, especially bajra, rye and jowar get infected with a parasitic ergot fungus Claviceps purpurea. Ergotism, a toxicosis results from eating grains contaminated with this fungus. Alimentary toxic aleukia (ATA) is another mycotoxicosis caused due to eating moldy grains.

 Asperigillus flavis and A. parasiticus growth in food results in the production of aflatoxins. This mycotoxin has been much studied. There are 14 chemically related toxins and one of them aflatoxin-B is most frequently found in food and is the most potent carcinogen known. Liver cancer due to aflatoxin ranks high in India.

Over 50 genera of bacteria have been associated with food poisoning. Bacteria cause food poisoning in two ways; due to food infection or intoxication. The former is on account of the organism present in the food during consumption. Salmonella species, vibro, parahaemolyticus, Escherichia coli, yersinia enterocolitiea, clostridium perfringens and Campylobacter jejuni, belong to this category. The bacteria then grow in the host and cause a disease. For example, Salmonella in food causes an illness called Salmonellosis. Diarrohea, abdominal pain, vomiting and fever are caused by this type of poisoning.

The second type of poisoning is due to the toxins produced by bacteria in the food prior to consumption. Examples of this type are Clostridium botulinum, Staphylococcus aureus and Bacillus cereus. These produce toxins in the food which cause illness in susceptible hosts. For example the disease caused by the toxins of Clostridium botulinum is known as botulism. The toxicity will last for 6-8 months and disturb vision, speech and swallowing. Progressive weakness and respiratory failure set in.

              Poisoning of food due to contaminants arising from food processing is also common. For example when fumigant like ethylene oxide is used to sterilize food under conditions in which steam heat is impartial, it reacts with inorganic chlorides in food to form toxic compounds.

Food poisoning or intoxication usually refers to gastrointestinal diseases caused by the ingestion of food contaminated by pathogens and their toxins. The toxins are called enterotoxins because they disrupt the functioning of the internal mucosa, causing symptoms such as nausea, vomiting and diarrhoea. Mostly food poisoning is caused by bacteria and viruses.

            Cholera, an epidemic in various parts of the world is caused by Vibrio Cholerae, mainly through water and food contaminated by fecal material. Botulism is a form poisoning caused by Clostridium botulism. This common source of infection is canned food that has not been heated sufficiently to kill the contaminating C. botulinum spores.

Staphylococcal food poisoning is a major type of food intoxication caused by ingestion of improperly stored or cooked food (particularly processed meat, chicken salad, pastries, ice cream) in which Staphylococcus aureus grow.

Salmonellosis or salmonella food poisoning is caused by over 2,000 Salmonella serovars. The most frequent one in humans is S. Serovar typphimurium. Human acquire the bacteria from contaminated foods such as bee products, poultry, eggs and egg products.

Shigellosis or bacterial dysentery is caused by several species of Shigella. Normally it is transmitted by direct fecal-oral route although water and food are involved in some of bacterial dysentery. 

Paper is made of cellulose obtained from pulp of cotton lint, wood, straw and rag. Blotting paper is an unsized paper, since sizing agents are not employed in the manufacture of this paper. This is in order to retain the absorbent property, which is more in blotting paper. This absorbent property is due to the presence of more microscopic capillaries, which exhibit more capillary action resulting in the easy entry and spreading of any liquid, which come in to contact. Another property of blotting paper is that it is not hard, since it is manufactured without loading.

 The ordinary writing paper is a sized paper. So it is impregnated with sizing and coating materials. This prevents the incorporation of microscopic capillaries. These papers are permanence, resistant to ink penetration and better finish. Polyvinyl alcohol, carboxyl methyl cellulose, alginates and certain wax emulsions in combination with starch are also used as loading agents for the manufacture of these papers. Tissue papers are entirely different from ordinary writing papers and blotting papers.

Unlike these two papers they are very thin, glazed and sometimes slightly waxed. Even though tissue papers are thin, they are very strong. Since they are highly glazed they are transparent. These papers are specially made for the purpose of taking carbon copies and packing cakes and butter.

 

A blotting paper absorbs ink by capillary action which is a natural phenomenon exhibited by liquids in the attempts to reduce surface tension.

Any thin tube having a very fine ne bore (say, less than one mm) is called a capillary tube. When such a tube is immersed n a liquid rises inside the tube to a level higher than that outside it. (Only liquids which have an angle of contact less than 90 degrees will show a rise. Other liquids like mercury will show a dip.)

Blotting paper is made of cellulose obtained from the pulp of cotton linter, wood or straw. A purified pulp paste is directly pressed to form blotting paper sheets without any treatment. So as to incorporate microscopic capillaries. When such a paper is placed in ink, water or any aqueous solution, the solution immediately enter in to these capillaries and spreads all over the sheet.

Capillary action is also responsible for many common phenomenon seen in our everyday life. It helps plants in raising the sap from the roots to the top through the stem. It also makes kerosene or oil in wick tip where it is burnt. 

The problem lies in power to weight ratio of the bike. Bikes that use diesel as fuel are heavy in size. The power output from the diesel engine is high and more over noise and vibrations are at a high level, prohibiting them in common use.

Diesel cannot be used with 50, 100 and 150 cc engines, because of high power output. Diesel engine is a compression ignition engine where diesel injected into a cylinder of high pressure and temperature compressed air, under a very high pressure.

            Atomized diesel particles come through a tiny hole of fuel injection nozzle burn and release mechanical power output. Design and manufacturing of such minute mechanical parts, withstanding high temperature and pressure is not cost effective.

And usage of diesel demands heavier   construction   of all   structural parts to endure high   vibrations. The cost   is   also high.   If the engine   is   not   serviced properly and periodically the pollutants level emitted will be very high when compared to petrol engines. At present only Enfield India Manufactures motorbikes which use diesel as fuel.

Yes, Liquefied petroleum gas (LPG) can be used in petrol vehicles without any harm to the engine. On the contrary, many benefits to the engine are provided by the use of LPG. It is a clean burning gas without causing deposits to the combustion chamber. The octane rating of LPG is significantly higher than that of petrol. So it can bear higher compression ratio conducive to higher efficiency. But this can only be achieved in dedicated engines but not in converted engines as is the practice. The converted engine has to switch back to petrol when the supply of gas from the cylinder is exhausted!

Nevertheless, clean burning characteristics with lesser maintenance, absence of mal-distribution from cylinder to cylinder and cycle to cycle (unlike that encountered in petrol engines) will result in better performance both fuel economy-wise and emission-wise. There is no danger of benzene and other carcinogenic aromatics in the exhaust much less the much dreaded lead since it has naturally a high octane value.

 In the U.S, where there is intensive research on alternate fuel technology,  LPG or Propane, as it is called there, accounts for the largest number of vehicles working on this alternate fuel technology.

            There are two types of light duty vehicles: dedicated which operates exclusively on LPG and the dual fuel, which can operate on either LPG or petrol.

Bulk of LPG is propane with varying quantities of ethane and butane; such that it can he liquefied at ambient temperatures by pressurizing it to moderate range of 25 to 125 psi, depending on temperature. These pressures can be safely contained in simple thick-wall steel fuel tanks. This is in contrast to natural gas which must be pressurized to 3000 psi and stored in reinforced tanks, or chilled to minus 260 F and stored in double-wall cryogenic tanks.

Two crucial factors in the use of LPG must be borne in mind. First: Safety. Have sufficient safety measures been taken to prevent risk involved in case of an explosion of gas cylinder consequent to a possible disastrous collision? Look at the damages to innocent road user by careless installation of the conversion kit.

Has the government given a nod to this conversion taking into account whether or not the vehicle can be insured against the third party risk. A gas cylinder explosion can be as disastrous as a bomb blast! Next a moral obligation to society: Is there any chance that the LPG used is from the highly subsidized domestic sources. Let us learn from the experiences of adulterating petrol with the subsidized kerosene.

A scientific answer to this relevant question must also be in tune with the societal benefits of science to the community. Hence this is a warning note to the otherwise a commendable fuel from a purely scientific point of view.