Category Applied Science and Technology

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.

Bond paper belongs to the class of paper called ‘writing’ paper. It is made of cotton rag pulp which gives it strength. It is also sized for opacity and toughness and the metallic sound. Bond paper is different in its non- absorbent qualities as it is well sized so as not to absorb water-based writing ink. It is also tough and strong due to rag content in the pulp.

The sizing may be animal or gelatin or tub sized as distinct from engine sizing used for printing paper. The word ‘bond’ owes its origin due to the fact that originally IOU’s or promissory notes (bonds) were widely using this rag content durable paper.

Smooth printing paper is used for photocopying to attract the toner powder. In the U.S, hardwood sulphite is beaten well and hydrated to produce bond paper. It produces crackle (sound) and results in a high mullen (tensile strength) bond paper which is water marked as ‘sunlit’, JK and ‘Executive’. They are used in making paper for insurance policies, stock certificates, bank notes and other important documents for longevity. There are machine dried and air dried bond papers. 

            

Not any more than eating enough of any other protein, according to dermatologists. If someone is severely protein-deficient, high-quality protein might make a difference, it is said. As an average person gets plenty of protein, it would take someone who was ‘malnourished or a food faddist, to see a real benefit.

 It’s the same case with calcium; it would help the nails if the person were totally deficient, but if one’s bones are falling apart the person would not care about their nails. To make a real difference in nail strength, it is said, they are to be treated as carefully as the skin is. If you moisturize your hands after you wash the dishes, for example, rub the product into the nails as well. Keep your nails out of harsh chemicals. Wear gloves to do housework.

People whose nails are really brittle might even wear latex gloves when washing hair. Nail polish and other drying nail care products are to be avoided. Polish covers nail abnormality but actually make it worse, according to them, but polish remover, even the kind without acetone, is incredibly drying to nails.

What if your nails split rather than break? There are two kinds of splitting, according to dermatologists. The longitudinal splitting is something that occurs with age. Ridges and valleys develop, and splitting occurs along fracture lines because the nails dry like the skin. Again, help for this problem lies in moisturizing. The nails are to be wet and covered with Vaseline or even alpha-hydroxyl acid, it is suggested. It is not a quick fix, but must be done until the nail grows out entirely which takes 6-8 months. The other kind of splitting, called onychoschisia, which occurs in layers at the tip of the nail, is something, dermatologists find most often ‘in chronic polishers or those who use fingernails as tools.’

Hairs are made of dead epithelial cells strengthened by a protein called keratin. Actually, epidermis (the upper layer of the skin) descend into the dermis (inner layer of skin) to form flask shaped structures. These structures hair follicles have a group of epithelial cells that form a bulb. Below this bulb is the dermal papilla or hair papilla which consists of connective tissue, supplied richly with blood vessels and connected by nerves. This region supplies nourishment to the root cells of the hair.

The epidermal cells of the hair root are very active and they divide rapidly. As new cells form, the old cells are pushed upwards in the form of hair.

Beyond the bulb region, the cells die and become horny with the addition of keratin. As the dead cells continue to add rapidly in the root, the shaft grows in length and pierces through the epidermal layer and projects out as hair. The hairs normally grow for about 18 cm in a year.

Thus the root is the only living part of the hair. Hence, when the hair above the skin is cut, we don’t feel any pain. But, if the hair is pulled out, because of the presence of the sensory nerves in the hair papilla, we feel the pain. A similar mechanism operates in the nail also. The root or matrix of the nail is made of soft epithelial cells and the growth takes place here as the cells are active and alive. As the cells grow the older cells are pushed out as the nail plate. Beyond the root region, the plate cells die and become horny again with keratin addition. Beyond the finger tip these horny cells project out as nails. From the root to the finger tip, the nail plate is connected to the underlying epithelial cells (nail bed), which are provided with blood vessels and nerves. When we pull this part out, we feel the pain, because the epithelial cells are also damaged. But beyond the finger tip, it is all dead cells and no pain is felt when cut. The nails grow to about 5 cm in a year.

Farm lands and fields are not smooth and hard like play grounds, and so the steering effort needed to be put in by a driver has to be more to drive a vehicle in them.

In case of tractors, the front wheels are meant for stability and steering only. They are small in size to aid in steering and to give a better view of the field to the driver. But the big rear wheels have specially designed tyres for an entirely different purpose – to give a better grip on the ground. Their larger surface areas in conjunction with a low air pressure (0.8 – 1.2 kg per square cm) ensure adequate contact area (and friction) between the tyre and the ground. This is necessary to increase the driving force in muddy fields.

If rear wheels are also small in diameter and width, their contact area with the soil surface will be small. This may, if the field is muddy, make the wheels penetrate and get bogged down in the mud, due to its own weight. If the wheels are large this cannot happen as a considerable amount of sand beneath the tyres has to be disturbed.

Lead in the form of tetra-ethyl lead (TEL) is added to petrol to suppress abnormal combustion called knocking.  High local pressure due to knocking results in excessive noise, power loss and eventual damage to petrol engines fitted to any motor vehicle – be it two, three, or four – wheeled vehicle. But the question posed apparently addresses two-stroke engines which are commonly used in two and three wheelers, accounting for nearly 60 percent of petrol consumption and discharging nearly 20 percent of raw petrol with lead directly into the atmosphere.

The unleaded petrol recommended for use in cars fitted with catalytic converters, can be safely used for any petrol vehicle. In fact, the use of unleaded petrol causes cleaner combustion without deposits on the chamber walls. These deposits caused by lead are known to hide raw petrol in their crevices and prevent them from combustion. These are discharged in the exhaust causing pollution besides higher fuel consumption. The engine also requires frequent decarbonising due to excessive deposits.

 In two stroke engines, the actual compression ratio is lower than the normal compression ratio, based on the ratio of cylinder volumes at the outer and inner dead centres, as the actual compression will not start until the piston covers the ports on the return stroke. So the probability of knocking in a two stroke engine with unleaded petrol is lesser than that in a four stroke engine of the same nominal compression ratio.

For leaded engines, the valves have to be coated with anti- corrosive materials and the piston rings need special treatment. Now comes the logical question: why not use unleaded petrol to all vehicles?

 Unfortunately, all our refineries are not geared up with modern refining methods like hydro-cracking or quality feed-stocks to produce lead-free anti-knock petrol (designated by high octane number) to meet the demands of all the petrol driven vehicles. The amount of lead depends on the fuel composition-paraffins with long chains needing most, the shorter and the branched chain hydrocarbons lesser and the aromatics the least or none, if the compression ratio is compatible.

In India, the limit fixed varies from 0.18 to 0.56 g/litre depending on the feed stocks available and the type of refining process infrastructure. Whatever unleaded petrol produced is only restricted to those cars plying in metropolitan cities which are mandatorily fitted with catalytic converters. Otherwise, leaded petrol will poison the catalysts. The problem of alternatives to leaded petrol is engaging the attention of the researchers for a long time. Natural gas or LPG is admirably suited as they are inherently knock-resistant because of their short chains.

Alcohols are also excellent knock -resistant fuels. Tertiary-butyl alcohol (TBA) and methyl tertiary-butyl ether (MTBE) have also been contemplated as additives.

 Lead poisoning is a serious health hazard. Many social organizations, worldwide, are making a study of this and are creating public awareness to this problem.

 The George foundation, a charitable and non-profit trust has pioneered a project ‘Lead Free’ in Bangalore and is collecting data in order to test and treat people severely affected by lead pollution. Hopefully, the project would be extended to other metropolitan cities.