My Science School

                    When a cat wants to express contentment or pleasure, it purrs. Purring of a contented cat results in a low vibrating noise. It is a kind of low, continuous rattling hum and has nothing to do with a cat’s real voice. A mother cat purrs when it wants to call her kittens for feeding. At birth the kittens cannot see, hear or smell. So in the initial stages after birth, it is the purring of their mother that helps them to communicate with her. Once the kittens start feeding themselves, the mother stops purring. It implies that purring began as a kind of homing device.

               Now the question arises how a cat produces the purr? 

               Purr is caused by the vibrations in a cat’s vocal cords. When a cat takes air into its lungs, the air passes through the voice-box that contains the vocal cords. If the cat then wants to express its satisfaction about something, it will allow the vocal cords to vibrate as the air passes in and out of the lungs during breathing. When it chooses not to purr, the passing air does not affect the vocal cords and thus doesn’t produce any such sound.

                Although there are many other members of the cat family such as lion, tiger, leopard, cougar, jaguar, ocelot and lynx, their throat structure is quite different from a cat and hence they cannot purr. However, they can make other kinds of sound.

               It is said that only man has highly developed reasoning faculties and hence can think and act accordingly. But there are animals that sometimes, with their superior senses excel man in certain activities. For example, dog has an excellent power of smell and often helps man in his day-to-day life. Like man there are some animals who take reasonable care of their offspring. But how do these animals recognise their young ones?

               Among the animals where parental care is prevalent, it is important for the mother and her young ones to recognise one another, so that they do not lose contact. This is done through one of their four senses: smell, sound, sight or touch.

               Most of the mammals recognise their offspring by smell. It is a common practice among dogs, deer, sheep, horses and seals.

               It's interesting to note that among a flock of sheep every mother can recognise her own young ones by smell and ignore others. Among some other animals, when a young one is born, its mother sniffs it and the smell remains in her memory. Thereafter the mother easily locates her baby by sniffing all the babies around until she finds her own.

               Among the birds recognition is more by sound. Each parent bird has her own special ‘mother call’ which the baby immediately recognizes on hatching. An Austrian naturalist, Dr. Konard Lorenz, has made a special study of geese. He conducted his study just before some gooslings were about to hatch. He immediately removed the mother goose and sat by the eggs himself. As the babies hatched he gave the ‘mother call’. As a result, they followed him everywhere believing him to be their mother as they recognized only the sound. But since he was too big for the young geese they got confused when he stood up. However they were quite happy to follow him when he crawled about on hands and knees.

               To some animals, shape and size also matter as the sense of touch also plays an important role in the recognition of young ones.

 

                           The botanists study the internal structure of plants mainly by examining their cross section under a microscope. These thin slices can tell us a lot about the structure of the cells that make up the plant and how they vary in different parts of the plant. In 1665, a scientist named Robert Hooke looked at a piece of cork (a material from the thick outer part of certain trees) under a microscope and saw that it was made up of many tiny compartments. He named them cells and this term has been in use since then. The equipments needed for obtaining the sections include a sharp razor, a small fine brush and a number of watch glasses and microscopic slides. The razor is stroked across the top towards the body, cutting off thin slices as required. Cross-sections as well as the longitudinal pieces are obtained in the same manner. To obtain best results the razor and the material must be kept moist with water in case of fresh material or alcohol if the specimen is a preserved one. To prevent shrinkage the sections shaved off are brushed into water or alcohol. For quick examination the sections are placed on a slide with a drop of glycerine. The thin ones that show the cells clearly can be stained for permanent use. In fact staining is a process of adding dyes to show the different tissues in different colours. Many stains are dissolved in alcohol and before staining the sections must be placed in alcohol. After a certain period in the stain(s) the section is transferred to a series of watch glasses full of alcohol. This removes water and the excess stain. The alcohol is removed by dipping the sections in clove oil or benzene. The section is then placed on a clean glass slide with a drop of Canada Balsam (a resinous glue). A thin glass is added as a cover-slip and sealed by warming the balsam to harden it. The slide, properly labelled, can then be kept and examined whenever necessary. Details of time exposure for staining varies with the stain and material used. The information can be collected from a text-book or worked out by practice. In laboratory analysis many modern techniques are being adopted for in-depth studies on the subject.

 

     

              When Darwin propounded his theory of ‘Survival of the fittest’, it created a great deal of controversy during those days. But gradually it started receiving a wider acceptance as many species were found to be either extinct or facing extinction for the reasons best explained by Darwin. Since the evolution of plant and animal lives, quite a few of them have faced complete extinction and others are facing the dangers of extinction. Hence the conservation of certain species that face extinction has drawn the worldwide attention. These species have been categorized as ‘endangered species’. 

                    Factors responsible for endangering the existence of these species are both natural and man-made. Firstly, the increasing human population is encroaching more and more land, and thus creating a scarcity of land for the wildlife to survive. Forests and heaths have been removed to make way for farming. Large-scale deforestation for wood and industrialization is another cause of the loss of wildlife. Secondly, man has hunted down many animals to extinction — auk and dodo are distinct examples of it. Pollution is also affecting the lives of many animals. Every year millions of sea-birds die unpleasant deaths as their feathers get covered with sticky, black oil waste. The natural causes are the unsuitable conditions of temperature and pressure, lack of proper food material, natural calamities etc. 

 

 

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            An affirmative reply to this question is amazing but true. It is a fact that many trees can produce the fruit of another kind of tree by a simple method called ‘grafting’. It is an artificial method or technique of vegetative reproduction in which a small branch or bud of any desired plant is inserted into another rooted plant. This is called plant propagation. If a bud from a twig of pear tree is carefully inserted in a slit made in the bark of a quince bush, a pear twig will grow. The quince bush will bear both pears and quinces.

            In the same way, an almond tree can be made to produce both peaches and almonds. Although sometimes grafting is used to produce freak trees and bushes, this technique is of immense importance in agriculture. Lots of experiments in this field are still being carried on to produce better and new varieties of fruits, flowers and corns etc.

            The greatest advantage of grafting is that it can be used to better the quality and quantity of a particular product. It is possible for a nurseryman or gardener to be sure that his young trees or shrubs will bear the same quality and variety of fruit as the parent tree. A twig taken from a tree and grafted into another tree will produce the same type of fruit borne by the tree from which it was taken.

            There are many methods for inserting the budded twigs or scions, as they are called, into the stock of another plant, but two rules must always be followed. First, only related species of trees or shrubs can he grafted. This implies that apples can be grafted onto pear and quince trees, and peaches can be grafted onto apricot, almond, plum or other stone fruit trees. It is impossible to graft apples on a peach tree. Secondly, the cambium layer (a layer of actively dividing cells) which carries the vital sap of scion must touch the cambium layer of the stock on which it is grafted. Otherwise the grafted twig cannot grow.

            There are different techniques of grafting. It can range from inserting a single bud under the bark to grafting long twigs across the wound of a tree in order to heal wide wounds in the bark. Tissue culture is popular these days in which cells from a plant are removed to propagate in another plant to obtain a hybrid product or the product of the original plant.

            The technique of grafting is now widely applied in case of animals as well as human beings. There have been surgical operations in which a bone taken from the ribs has actually been grafted onto the nasal bone to form a new nose. But the best application is in cases of severe burning where the healthy skin from one part of the body is grafted onto the burnt tissues to remove scars.

               One of the fundamental differences between plants and animals is that animals can move from place to place whereas plants lack mobility. But inconsistent with this general distinction, there are some plants which move on their own. For example, slime molds have amoeba like movement whereby they ‘coze’ from one place to another. Some types of algae have whip like flagellas, they use to paddle themselves through water. Many plants particularly, the lower ones, produce mobile male gametes which swim about in order to find eggs to fertilize. Englena is a protozoa which is capable of swimming. Apart from these exceptions, the movement of plants is usually confined to the movement of some parts of it while the plant itself remains fixed at one place.

               There are three basic types of plant movements: tropisms, nutations and nastic movements. 

               A tropism is a growth response towards or away from something caused by a specific environmental stimulus. The direction of growth is determined by the stimulus. When it is towards the stimulus, it is caller positive tropism and when away from it, it is called negative tropism.

               Tropisms are caused by special growth hormones called auxins. In most of the cases, the stimulus causes the auxins to collect on one side of an affected organ. This causes the cells on that side to grow and divides more quickly than the cells on the other side. As a result, the organ bends away from the side with the most auxins.

               Tropism is of several types. Phototropism is a growth response to the stimulus of light and auxins are concentrated on the side away from the light. This causes stems and leaves to grow towards light and roots grow away from light. Geotropism is the growth towards the gravity of earth. Roofs show positive geotropism while stems show negative geotropism. Hydrotropism is the growth response to the stimulus of water. Roots grow towards water and often move great distances to areas of moist soil. 

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              He was the man who first proved that air contains two gases: oxygen and nitrogen. Also he established that when a substance is burnt it combines with oxygen in the air. This really moved chemistry into the modern age, because it explained for the first time what really happens during the important chemical process of burning. This great scientist, Antoine Laurent Lavoisier, was born on August 26, 1746 in Paris and is called the ‘Father of Modern Chemistry’. After completing his education, he first became a lawyer and worked as a tax collector. In his spare time he conducted research work.

              In 1766, he won a gold medal for his suggestions on how to light the streets of Paris. He was later given the job of a Gunpowder Officer. Lavoisier did a great deal of research on combustion. In 1772, he proved through an experiment that the ash from burnt metals is heavier than the original metals. Earlier people believed that when such things are burnt, they give off a substance called phlogiston. Lavoisier proved that during the process of burning something was added to the substance. 

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Morse code is a system of sounds that telegraphers and radio operators use to send messages through wire or radio. This involves a system of dots or short signals, dashes or long signals and spaces. Each letter of the alphabet, plus numbers and other symbols, are represented by groups of dots and dashes. The Morse code is named after Samuel Morse of USA who developed it in 1938. He also patented the telegraph in 1840 and was credited with the invention of telegraph.

The first message in Morse code was taped out in the United States over a telegraph line from Baltimore to Washington by Samuel Morse on May 24, 1844. The message was, ‘What hath God wrought’. Morse code can also be signalled by lights.

In 1837 Morse exhibited his first successful telegraph instrument. By 1838 he had developed the Morse code. But it was not until 1843 that Morse built the first telegraph line in the United States from Baltimore to Washington. In the following year, i.e. 1844, he succeeded in sending the first message. 

Telegraph messages are sent by pressing down a telegraph key. The dot is made by pressing down the key and releasing it quickly. This produces a rapid ‘click-clack’ sound in the receiver at the other end of the wire or the radio receiver. In the case of radio telegraph, the sound is more like a musical note. A short dash is held twice as long as a dot. A long dash is equal to four dots. The space between letters is sounded by ‘three dots’. A space that is part of a letter combination equals two dots.

Even today, in many countries, all telegraph messages and many new items are being transmitted by Morse code. Today most of the telegraph messages are sent by automatic printing telegraph machines called teleprinters, and by automatic facsimile like fax or electronic mail.

 

             A synthesis of the Quantum theory of Neils Bohr and the Field theory of Albert Einstein was evolved from a new theory of a great Indian scientist — Satyendra Nath Bose. The theory put forward by Bose explained the behaviour of subatomic particles. He showed that photons—the packets of energy, could behave quite differently from the assumptions of that time. Later Einstein further developed Bose’s ideas into a set of calculations which later came to be known as the ‘Bose-Einstein’ statistics. Though Bose and Einstein never worked together yet their long association was maintained through correspondence.

            A student of mathematics knows about Bose- Einstein statistics. This was a new type of quantum statistics and the particles to which this statistics is applicable are called Bosons, after the name of Bose.

           S.N. Bose was born in Calcutta on January 1, 1894. His father Surendranath Bose was a railway official. He went to Hindu School, Calcutta, for his primary education. There is an interesting episode which offers a glimpse into his genius. In school he once got 110 marks out of 100 in the mathematics paper because he had solved some problems in more than one way. His teacher predicted that one day he would become a great mathematician.

           After school he went to the Presidency College, Calcutta, in 1909. He became favourite with most professors for his brilliancy. He always stood first in all his exams—Intermediate, B.Sc. and M.Sc. 

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               The first gyroscope was devised by a German, G.C. Bohmenberger, in about 1810. But it was named thus by a French Physicist Leon Foucault in 1852, when he used the device to demonstrate the rotation of Earth. Its name has its origin from two Greek words: gyros mean turn or revolution; and skopein means ‘to view’. Therefore, gyroscope means, “to view the turning”. 

                This instrument is based on the same principle as that of a spinning top. We know that as long as the top keeps rotating, it remains upright and resists the force of gravitation. Similarly in a gyroscope, a wheel is mounted at such an angle to the rest of the apparatus that it is free to revolve around any axis.

                 According to the basic principles of motion — any spinning object resists an attempt to change the direction of its axis — the imaginary straight line around which it revolves. Thus you can move a gyroscope up, down, forward, sideways or backwards, and feel no resistance. But the moment you try to turn it through an angle you will meet opposition.

                A gyroscope basically has a heavy wheel. Most of its weight is concentrated in the rim. This gives the wheel a large moment of inertia. It resists attempts to change its position. If an attempt is made to tilt its axis, it will start moving in another direction, in a circle. This is known as precession. 

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               Homi Jehangir Bhabha a name considered synonymous with India’s atomic energy programme, was a great son of India. His contributions in the field of nuclear science gave India a giant leap in the field of science and technology. Consequently this led to the growth and progress in other fields. Indian atomic research has attained great heights today only due to the efforts of Homi Bhabha.

               Dr Bhabha was born on October 30, 1909 in Bombay in a wealthy Parsi family. He had his early education in Bombay. After graduating from the Elphinstone College and the Royal Institute of Science in Bombay, he went to Cambridge University for further studies. From there he got his engineering degree in 1930 and a Ph.D. degree in 1934.

During his stay at Cambridge University, he worked with Niels Bohr on Quantum Theory. Later Bhabha worked with Walter Heitler in the field of cosmic rays. He became well-known for his theoretical explanation of the phenomenon of Cascade showers in cosmic rays. He did significant work in identifying the elementary particles called mesons. 

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            Dr Vikram Sarabhai was not only an imaginative and creative scientist but also a pioneering industrialist and an astute planner. He made significant contribution in the field of cosmic ray physics and in the development of nuclear power and space programmes. When Dr Bhabha died suddenly in 1966 in a plane crash, it seemed almost impossible to fill the vacuum but fortunately a worthy successor could be found in Dr Sarabhai. He took up the nuclear programmes with a challenge and also added fresh dimensions to the space research programmes.

            Dr Sarabhai was born on August 12, 1919 at Ahmadabad in a rich industrialist family. His early education was in a private school in Gujarat College at Ahmadabad. He then went to Cambridge, England, and obtained his tripos in 1939 from St. John’s College. He then came back to India and staled research work in the field of cosmic rays with Sir C.V. Raman at the Indian Institute of Science, Bangalore. In 1945 he went back to Cambridge to carry out further research on cosmic rays. There in 1947 he obtained a Ph.D. degree in the same field.

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               Shanti Swarup Bhatnagar Memorial Award is given every year for outstanding research by the Council of Scientific and Industrial Research (CSIR). It was instituted in 1958 in the honour of its first Director General Dr. Shanti Swarup Bhatnagar. The awards are given in the fields of Physical Sciences; Chemical Sciences; Biological Sciences; Earth, Atmosphere, Ocean, and Planetary Sciences; Engineering; Medical Sciences and Mathematics (alternate years). Each award carries a cash prize of Rupees one lakh and a certificate.

               Shanti Swarup Bhatnagar was a renowned Indian chemist. He was born on Feb. 21, 1894, at Bhera in West Punjab. He obtained his M.Sc. from the Punjab University in 1919. After taking his D.Sc. from London University under Prof. Donan, he worked under Prof. Haber at Kaiser Wilhelm Institute, Berlin, and later under Prof. Freundlich, an expert on colloids. 

               He was a Professor of Chemistry at Banaras Hindu University from 1921-24. From 1924 to 1940 he worked as Director of the University Chemical Laboratories, Lahore. There he made significant contributions in the field of physical chemistry, especially in magneto-chemical studies. He also wrote a book on magneto-chemistry.

               He became the first Director General of Council of Scientific and Industrial Research (CSIR) in 1940 and held this post till his death. In 1943 he was made a Fellow of the Royal Society of London. In the same year the Secretary of the Royal Society Prof. A.V. Hill visited India to advise the government on the coordination of scientific research in India. Dr. Bhatnagar was one of the members in the meeting along with Hill, Saha and Bhabha.

               In 1946, when Pt. Nehru was the head of the Interim Government, Dr. Bhatnagar took up his views on the development of science in India to translate them into reality. He concentrated on applied sciences and managed to get substantial funds from industrialists for the building up of research laboratories. He opened a chain of National Research Laboratories in India.

               This great scientist died on Jan. 1, 1955. After his death, Bhatnagar Memorial Award was instituted in his honour. 

                In the 19th century when India was excelling in various fields like fine arts, literature and philosophy, her contribution in the field of science was almost negligible. It was Sir Jagadish Chandra Bose, who with his inventions in the second-half of the 19th century, not only made a name for himself but also put India on the science map of the world. 

               Bose was born on November 30, 1858, in a village of Bengal. After studying physics at the Calcutta University he went to England for further studies. He graduated from Cambridge University in 1884, and after coming back to India he became a professor of physical sciences at Presidency College, Calcutta from 1885 to 1915. He was a doyen of Indian science; a pioneer in the field of physical and plant physiological researches.

               He had a deep interest in animal and plant life right from his boyhood. After becoming the professor, he got an opportunity to work in his cherished field. He was the first to realize that both animals and plants have a great deal in common, but he did not have any instrument to prove it. To begin with, he designed and built a very sensitive machine for the detection of minute responses of living organisms to external stimuli. This instrument was called crescograph. It magnified the movement of plant tissues to ten thousand times of their original size and could record the reaction of plants to manures, noise and other stimuli. He is also credited with inventing a wireless transmission system that went unrecognized, much before Marconi. 

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            The first model of a ballpoint pen was patented in 1888 by an American John H. Loud for writing on rough surfaces. But a successful ballpoint-pen, like the modern one, could not be developed till 1943. In fact, the American Air Force is mainly responsible for its invention. The Air Force demanded a special type of pen which could be used by the aircraft crew during flights. They required a pen which would not spill ink due to the reduction in air pressure at high altitudes. Such a pen could only be a ballpoint pen and hence there was a very fast development of it after this demand. Later on it became so popular that even the common people began to use it.

            The ballpoint pen has a hollow body made up of some metal or plastic material. It has a cap, a spring and an ink-refill with a tiny brass ball (writing point) fitted at its one end. The cap controls the writing point. The spring helps the writing point to move up and down. The refill is generally made of polythene and is filled with different colours of ink. 

            The ink used in ballpoint pen is specially formulated to be thick so that it may not leak. Its flow, however, remains smooth and unbroken lines can be drawn with the help of these pens. The ink is drawn through internal ducts in the socket by capillary action (a phenomenon in which the surface of a liquid confined in a narrow-bore tube rises above level.)

            A ballpoint pen has many uses. No blotting paper or inkpot is needed when it is used. This pen writes fast. Its ink does not spill on paper. The words written by it are not affected by water. It has certain disadvantages also. Unlike a fountain pen it does not make broader or finer strokes. It tires the hand more quickly than an ordinary pen because more pressure has to be exerted which using it.

            In the 1960s, soft-tip pens were developed in Japan. In these pens, the ink flows through a pad when pad touches the writing surface. During 1980s ballpoint-pens with carbide tips became very popular.