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| SCIENCE TRIBUNE | Thursday, December 28, 2000, Chandigarh, India |
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Pearls, beads and necklaces from space
Unseen dark matter fills the sky Award for flyash brick
innovation Rendering
residual waste harmless
Science Quiz
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Pearls, beads and necklaces from space YOU would have read about diamonds present in the core of a planet of our solar system in an article published in Science Tribune sometime ago. But to arrive at that planet is a farthest possibility and then to dig out the diamonds from its core is almost an impossible task. But you can get pearls, beads and necklaces from space very easily. Unfortunately in this case too, you will get them in their 2-D shape (i.e. on a paper) and not in 3-D solid structure. In this experiment two electrodes oriented north-south geographically are used having a spacing of 200 meter. Recorded currents are first pre-amplified (2dB) and then again amplified by 3dB. Low-pass LC filters as well as RF filters are used to avoid undesired signals. The received signals can be recorded both on rapid-run telluric current charts and on rapid-run magnetographs
(Pearls, beads and necklaces are shown in the figure at the top.) Space scientists have generalised the usage of the word ‘‘Pearl’’ by applying it to intervals of amplitude enlargements in any micropulsation (as the received signals are known) sequence, even for pulse intervals as large as several minutes. Some scientists (for example Dr R.R. Heacock and Dr V.P. Hessler from Geophysical Institute, College, Alaska) think it improper and unfortunate to call such signals as pearls. Because of this these signals are also called as Pearl-type micropulsations, Benioffs pulsations, simply pearl pulsations (PP) as well as hydromagnetic emission. These emissions have time period in the range of 1 second to 5 seconds and have electric field up to 300 microvolt/meter. Sequence of pearls formed by a nearly constant pulse frequency is called a necklace of pearls. A necklace may or may not have similar pearls. When two or more pearl necklaces are superimposed, ‘‘beads’’ are formed by the interaction of different signal frequencies (remember ‘‘bears’’ generation when two sound signals having almost equal frequencies superimposed) Thus whereas ‘‘beats’’ are the beats of two interacting frequencies, pearls are the equally spaced intervals of amplitude enhancements associated with a single wave frequency. How does pearl evolution take place in earth’s magnetosphere? Actually pearls are the Alfven wave trains that bounce between magnetic conjugate points along geomagnetic field line. These are amplified by the energetic protons which are trapped in radiation belts/rings currents around the earth. The bunches of trapped protons having energy in the keV-MeV range oscillate between the hemispheres with periods of 1-5 seconds and drift around the earth in a few minutes. Thus a pearl is formed as the proton bunch drifts over the recording station (or receiver), each successive pearl represents a revolution about the earth by these drifting protons. Whereas the signal gets energy for amplitude enhancement, protons lose their energy and are precipitated out of radiation belts. Though pearl evolution is a worldwide phenomenon, size of the pearl will depend upon the degree of absorption of these signals by cold protons/electrons. Actually, whenever these signals (amplified or un-amplified) pass through the E-region of topside ionosphere (120-800 km) above earth surface), these may be attenuated by cold plasma populations present there. The fluxes of energetic protons present during the propagation of the signal time of observation and geomagnetic latitude of receiver also affect the size of the pearls and beads. The size of receiving antenna also affects the intensity of these emissions. Experiments have shown that x-ray bursts and pearl-type micropulsations (PP) tend to occur simultaneously after sudden commencement of geomagnetic storms. This indicates that these emissions are also caused by bunches of energetic electrons which produce x-rays. In this case bounce frequency of energetic electrons will be the emission frequency of the pearls. Thus pearls (also known as Pc 1 signals) when received bring much valuable information about morphologies of ionosphere, megnetosphere and other regions in the space. These can be recorded not only on the ground but aboard satellites, too. |
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Unseen dark matter fills the sky UNIDENTIFIED flying objects fill the universe that surrounds us. This was first discovered in 1930 and research done since then finds that this “dark matter” is at least 40 times as heavy as all the visible stars and planets put together. These invisible objects disturb the motion of the galaxies and change the speeds at which they recede from our planet. They cause deviations from the famous Hubble’s law that says that the further away a star, the faster it recedes from us. The unseen dark matter also slows down the arms of spiral galaxies as they spin around the central core. In fact, this was how it was first discovered that there was something out there that exerted a gravitational pull on the visible stars in the sky. It is now certain that there is so much invisible matter around that our universe in on the verge of a collapse or implosion due to its own weight. Observations also notice that the interstellar gas in the galaxy is ionised. Electromagnetic radiation (photons) must have caused this ionisation but where these photons came from is not known. Another related fact is that the giant gamma ray bursts that astronomers have observed from time to time require huge energy transfers from the core of a heavenly explosion to the surface of the burst, which may be a thousand kilometres away. The mechanism for this enormous energy transfer has not yet been identified. Recently, the ROSAT orbiting X-ray telescope detected rather intense X-radiation from the dark side of the moon. This shadow side of the moon emits up to a quarter of the intensity from the bright side. One suggestion made was that the solar wind hit the dark side of the moon to produce these X-rays but this explanation does not account for the observed intensity. However, two years ago, X-ray astronomers found that the dark side of the moon was 10 times brighter than expected and this was possible due to an X-ray emitting region around the sun. In 1962, radio astronomers discovered quite by accident that a region around the sun emits very low energy X-rays. It is true that hot gas spews out from the nuclear furnace within the sun and emits ultra-violet radiation, but this gas in not hot enough to be a source for the detected X-rays. From measurements of the optical spectra of the sun and during solar eclipses, it has also been found that the sun as well as many other stars also have outer layers that are enormously hotter than the inner photosphere, and this outer layer can emit high energy radiation. These contribute to a background of X-rays in the universe. The solar corona has been studied with optical spectroscopes for a century or more and X-ray spectra from the sun have been measured to great accuracy for the last 50 years. Optical spectra confirm that the temperature of the surface of the sun, barely 100 kilometres under the solar corona, is around 6000 degrees C. However, the solar corona temperature is more than 2 million degrees. While the temperature suddenly shoots up as one goes out of the sun the density of matter drops dramatically. This clearly shows that the corona temperature is not due to the transfer of energy through hot matter from the inner thermonuclear furnace. There has to be some other mechanism that causes this phenomenon. These various and mysterious phenomena can apparently be explained by assuming that there are new, and as yet undiscovered particles called axions. These axions stream out of the inner core of the sun and decay at the corona into electromagnetic radiation. the photons thus created can give rise to an external illumination of the solar atmosphere. The axion is a hypothetical elementary particle that was proposed to explain the absence of an electrical dipole moment for the neutron and to explain the lack of CP violation in the strong interaction. The axion has no electric charge, practically no mass, no spin, and interacts with ordinary matter (electrons, photons, quarks, etc.) only very weakly. Theoretical arguments suggest that the mass of the axion should be between a thousandth to a millionth of an electron-volt, or else in the range of between three and eight eV. An astronomical search carried out at Kitt Peak Observatory ruled out the heavier mass range. Axions would have been produced as abundantly as any other particle in the Big Bang, the primeval explosion that gave birth to our universe. Perhaps these axions condensed into a “Bose condensate” and this cold mass behaves as cold dark matter and that clusters of these condensates got together effectively to form galaxies and large-scale structure. In the presence of a strong magnetic field, the axion resonantly decays into two photons. As they interact weakly with matter the axions travel out of the sun and in the magnetic field of the corona they break up into photon pairs and light up the edge of the sun, and other stars with photons. Several experiments are in progress to detect the axion. An extremely low noise microwave cavity is located inside a large magnetic field for this purpose. The detector consists of a high-Q tunable microwave cavity cooled to a temperature of 1.5 Kelvin inside a large super-conducting magnet about one meter long with a bore diameter of 60 cm. Any microwave signal from the cavity is amplified by a very low-noise Ga-As amplifier. When the cavity is turned precisely to the axion mass, the detector should see an increase of the microwave intensity. The experiment, therefore, scans the frequency spectrum looking for such a resonance signal. Since one expects very few axions to be present, the expected signal is very faint. The sensitivity of the apparatus corresponds to only a few hundred axion decays per second. Early experiments at the University of Florida and at Brookhaven National Laboratory got negative results with this method, as the equipment did not have the required sensitivity. In the past few years the search for axions has been revived by a large experimental effort at several laboratories in the USA and in Japan. The largest group is at the Lawrence Livermore National Lab, with participating groups from Russia, University of Florida, Massachusetts Institute of Technology, Fermi National Accelerator Laboratory, University of California at Berkeley, Lawrence Berkeley Laboratory and University of Chicago.
— PTI |
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Award for flyash brick innovation BHANUMATHIDAS and Kalidas of the Institute for Solid Waste Research and Ecological Balance (INSWAREB) have been selected for an international award for their “sustained and outstanding contributions as regards to the use of flyash in bricks and concrete in India”. In a fax message sent by the Chairman of the committee, CANMET, Canada, to the recipients, it is mentioned that the International Conference Organising Committee has selected Bhanumathidas and Kalidas to this award which would be presented to them at the ‘Seventh CANMET/ACI International Conference on Fly Ash, Silica Fume, Slag and Natural Pozzolans in Concrete’ to be held at Chennai in July, 2001. The award ceremony will take place on Wednesday, July 25, 2001, at the Park Sheraton Hotel, Chennai. INSWAREB has developed a technology to manufacture floating bricks that contain as high as 70-80% flyash. This is technically called aerated concrete to manufacture which a high capital system called autoclave is needed which is also energy intensive. Keeping in view the economic scale of operation, almost all the technologies, manufacturing aerated concrete throughout the world, have adopted 150-200 m3 production per day at a plant cost of about Rs 20 to 30 crore. But several such plants have been bogged down in India because of exorbitant price of the end product, despite best of the technical virtues for aerated concrete. Bhanumathidas and Kalidas of INSWAREB have achieved a breakthrough whereby the autoclave is dispensed with but the aeration is maintained to render a lightweight product. It is possible to manufacture the product with density of 600-900 kg/m3 at a strength of 25-60 kg/cm2. The conventional clay bricks weigh about 1800 kg/m2 rendering the strength of 20-40 kg/cm2. They have achieved this feat by integrating the principles of their patented Fal-G technology with parameters of the age-old aeration process. Naming their product as non-autoclaved aerated concrete (NAAC), Bhanumathidas and Kalidas have achieved the strengths even in the absence of autoclave by manoeuvring the chemistry in the lines of Fal-G. By doing so, they hope to save energy by about 60-70% and, at the same time, improving the quality of the product which is possible by using flyash as high as 70-80% depending on its reactivity. Through this approach, it is hoped to sell this aerated concrete product at the rate of Rs 800-1000 per m3 as against Rs 2500-3000 prevalent now. |
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Rendering residual waste harmless FRENCH companies have developed a range of stabilisation processes to render residual waste from industries harmless. The industrial countries are confronted by an increasing volume of residual waste. In France alone, flyash form the incineration of household waste amounts to about 30000 tons per annum. There is clearly no possibility of releasing these materials, rich in heavy meals, untreated into the environment. The aim of stabilisation processes is to prevent potentially toxic components such as heavy metals or chlorinated compounds from being carried away by rainwater or surface waters. The stabilisation techniques, involving beaching-edge expertise in chemistry, mechanical engineering and thermal engineering, operate through the addition of mineral or hydraulic binders or the addition of organic binders to residual waste. Researchers at Sarp industries, located to the west of Paris, are using binders based on silicates and calcium aluminates for the stabilisation of industrial flyash and residual waste. Cold mixing of the binder and the waste first produces an increase in viscosity followed by the formation of very stable hydrated aluminate and silicates that adsorb potentially toxic molecules, cations and anions. |
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Science Quiz 1. Based on his extensive studies of the chemical composition of body tissues, this US biochemist identified for the first time the hormone adrenaline. Name this professor of pharmacology who also discovered insulin in crystalline form. 2. CJD — the human form of mad cow disease — has been under controversy in Britain recently because many scientists believe that it is caused by eating infected beef whereas others have failed to find this type of link. First identified in mid-1990s, CJD has caused many deaths in Britain. What is the full name of this disease? 3. It is believed by scientists that the sun keeps on pulling and pushing its magnetic fields rapidly, as if one pulls and releases a rubber band alternately. What is this phenomenon called, for which evidence has been found only recently? 4. What is common between Aldicarb, Cabaryl, Fenarimol, Methomyl and Thomaton? 5. HTLV was the first virus shown to cause cancer in humans. What is the full name of this virus? 6. What name is given to a configuration of a positive and an equal negative charge separated by a distance? What is the magnitude of the product of either charge and the distance between the two charges called? 7. ‘‘The rate of diffusion of a gas is inversely proportional to the square root of its density.’’ What is this law called? 8. We know that ammonia is synthesised by the Haber process. Which other process is a prerequisite to Haber process and why? 9. The surface of water in a glass capillary tube is concave whereas that of mercury is convex. Which property of a liquid causes its surface to acquire a curved shape instead of a plane one? 10. Name the first commercial communications satellite launched by the USA on April 6, 1965. Answer 1. John Jacob Abel 2. Creutzfeldt — Jakob disease 3. ‘‘Magnetic field line shrinkage’’ or ‘‘Reconnection outflow’’ 4. These are pesticides banned in some other countries but being used in India 5. Human T-cell leukemia virus 6. Dipole; dipole moment 7. Graham’s law of diffusion 8. Bosch process; to produce hydrogen 9. Surface tension 10. Early Bird Satellite. |
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