Category Science

Why do we perspire?

          Our body is like a furnace. The food we eat acts like fuel inside the body. It produces heat energy by the process of oxidation. Through this process about 2500 calories of heat is produced every day which can boil 25 kgs of water at 0°C. But what happens to this heat in the body?

          In our body certain metabolic activities are constantly taking place which do not normally allow the temperature to go beyond 98.4° F. Perspiration is one of the means through which the body furnace keeps its temperature normal. In fact, the body temperature is controlled by the ‘temperature centre’ located in the brain. This centre has three parts: control centre, heating centre and cooling centre.

          If the temperature of the blood falls below the normal due to some reason, the heating centre starts operating immediately. At the same time some special glands produce certain combustible chemicals which are used by our muscles and liver to raise the internal temperature of the body to the normal degree.

          On the other hand if the body temperature rises for some reasons the cooling centre goes to work. The process of oxidation slows down. Sweat glands start excreting sweat. Water, urea and some salts come out with the sweat. The sweat glands work fast only when the internal temperature of the body goes up. Sweat evaporates with the help of the body heat and this produces a cooling effect in the body. This process is similar to that of cooling of water in a pitcher during summer. Evaporation always causes cooling. Sweat, therefore, is a very effective process of controlling the body temperature. It also cleanses the internal parts. Many substances, harmful to the body, are excreted out through the millions of pores of the skin in the form of sweat. When the humidity is high, sweating causes uneasiness because the rate of evaporation under humid conditions decreases.

Why do women have a sweet voice?

          Generally the voice of women is sweeter than men. Even boys have feminine voice till the age of eleven or twelve years. But later it starts becoming deeper. Voice of girls, however, does not change much with age.

          Normally the age of eleven to thirteen years is known as the period of puberty. During this period some of our glands produce sex hormones. These hormones bring many changes in the bodies of boys and girls. In boys they are responsible for the growth and appearance of the hair under arms, auxiliary hair, pubic hair and facial hair. The voice of boys starts becoming deeper. Their bodies produce a hormone called ‘testosterone’ which is mainly responsible for changing the length and thickness of the vocal cords. This also affects the larynx. As a result a man’s larynx becomes larger than that of a woman. Man’s vocal cords are also longer than those of woman. Due to this the frequency or pitch of a man becomes lower than a woman’s and hence the male voice becomes deeper than that of a female.

          Though this hormone is not produced in the girls, yet a slight change takes place in their voice also. This change occurs mainly due to the further growth of their throat, mouth, nose and upper jaw.

 

Man Mohan Sharma

Man Mohan Sharma (born May 1, 1937 in Jodhpur, Rajasthan) is an Indian chemical engineer. He was educated at Jodhpur, Mumbai and Cambridge. At the age of 27 years, he was appointed Professor of Chemical Engineering in the Institute of Chemical Technology (UDCT), Mumbai. He later went on to become the Director of Institute of Chemical Technology (ICT/ UDCT/ UICT), the first chemical engineering professor to do so from ICT.

In 1990, he became the first Indian engineer to be elected as a Fellow of Royal Society, UK. He was awarded the Padma Bhushan (1987) and the Padma Vibhushan (2001) by the President of India. He has also been awarded the Leverhulme Medal of the Royal Society, the S.S. Bhatnagar Prize in Engineering Sciences (1973), FICCI Award (1981), the Vishwakarma medal of the Indian National Science Academy (1985), G.M. Modi Award (1991), Meghnad Saha Medal (1994), and an honorary Doctor of Science degree from Indian Institute of Technology, Delhi (2001).

Field:

  • Chemical Engineering

Awards

Professor Sharma is a recipient of a number of prestigious academic honours and awards including the 1977 Moulton Medal of the Institution of Chemical Engineers, and is himself commemorated in the M M Sharma Medal awarded by the same institution for outstanding research contributions.

 

He won the Leverhulme Medal of the Royal Society for “for his work on the dynamics of multi-phase chemical reactions in industrial processes”. He was awarded the Padma Vibhushan (2001), and Padma Bhushan (1987) by the President of India. He was INSA President (1989-90). He is a Fellow of the Indian Academy of Sciences, Bangalore, Honorary Fellow of the National Academy of Sciences (India), Allahabad, Fellow of the Royal Society, London. Subsequently he was elected Honorary Fellow by the Royal Academy of Engineering and is Foreign Associate of the US National Academy of Engineering.

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Shankar Abaji Bhise

Dr. Shankar Abaji Bhise  was an Indian scientist. Bhise has to his credit 200 inventions, for about 40 of which he took patents. In 1910, Sir Ratan Tata set up the Tata-Bhise invention syndicate in order to finance Bhise’s inventions. Among his inventions were a washing compound and type-caster machines, including the Bhisotype which could output 1,200 characters a minute.

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How is soil formed?

          Soil is the upper most surface layer of the earth in which plants grow and on which directly or indirectly, all life depends. It is composed of rocks, minerals, organic matter, water and air. It did not take one or two days for the soil to form but millions of years. Do you know how soil is formed?

          Millions of years ago, soil existed in the form of rocks. Since then weather and other natural forces like wind, rain, snow, water, heat etc. had been interacting with the rocks to break them into smaller fragments. These forces further converted the rock-pieces into sand. Bacteria, carbonic acid and other micro-organisms converted this sand into soil. In course of time bacteria converted the bodies of dead plants and animals also into soil.

          Soil is classified according to its colour, texture, chemical properties and climate. Colours of soil range from yellow and red to black. Soils are also categorized as acidic, alkaline and neutral. Extremely acidic or alkaline soil does not support plants. 

          There are three main types of soil a) Pedalfers – associated with temperature, humid climate, contain iron and aluminium salts, b) pedocalo – associated with low rainfall regions, contain soluable substances such as calcium carbonate and other salts and c) Laterites – tropical red or yellow soils heavily leached and rich in iron and aluminium. Based upon soil classifications, modern farming and plantation are made to yield maximum returns.

          An organic matter called humus is constantly being added to the parent soil. Humus makes the soil more fertile.

          Deep, well developed soil is divided into four layers called horizons. The top layer, where most plants grow, is called the A-horizon or top soil. This layer is rich in organic material and contains some minerals. The next is called B-horizon or sub soil. It is rich in minerals, especially in clay, but with little or no organic matter. Farmers often mix the A-and B-horizons by ploughing. The third is called C-horizon and it is a layer of weathered and shattered rocks. It is called the fragmented rock. It is quite similar to parent soil. The last layer is D-horizon or bed rocks. 

Why do objects appear coloured?

          Do you know why an apple or tomato appears red, the grass green, and the milk white when they are all illuminated by the same sunlight? In fact, the colour of an object depends upon the colour it reflects.

          The sunlight which appears white comprises of seven colours: violet, indigo, blue, green, yellow, orange and red. In sunlight, an apple or tomato appears red because it reflects only the red colour and absorbs the rest.

Grass appears green because it reflects only the green colour and absorbs all other colours present in the sunlight. A white shirt or milk appears white because it reflects all the colours of the sunlight. And a blackboard appears black because it absorbs all the colours of white light and reflects none. To prove this, focus red light on a white shirt and you will see that it becomes red. White objects take the colour of light falling on it. Similarly if we see an apple in red or white light it will appear red but in green or blue light it would appear black. It cannot reflect any other colour but red and, therefore, looks black in any other colour except red or white. This is how the various objects get their colour.