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| SCIENCE & TECHNOLOGY | Thursday, July 31, 2003, Chandigarh, India |
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Solar
power in agro-based industries 25 years of test tube babies Tunable “photon copier” on a chip Orphaned star clusters roam the universe
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Solar
power in agro-based industries
If such heat could be supplied through solar energy we could minimise the energy/environment problems in the country.
In the market we have only flat plate solar collectors available. They are inefficient, occupy huge surface areas, bulky and under no circumstances give a temp. of 150`B0C or so. Above all the cost of collectors is also not cheap. So, such collectors to be used for process heat is out of question. Technically speaking such collectors do not provide any concentration of solar insolation. As such we should not expect much from these collectors. The complexity of solar energy design (and therefore cost) are site specific and will vary considerably with the age, size, location and energy requirements for each operation. Further, the economic viability is a function of the number of days that the process needs energy, production on lines which operate 12 months in a year will be the first to find solar energy attractive, and the pay-back period will not be very long — ideally, not exceeding three to five years. So we have to solar collectors which provide concentration of solar insolation for giving fluid temperature of 150`B0C or so. Parabolic trough type solar collectors which provide concentration of solar insolation and also move with the movement of the sun for maximum heat absorption will serve the purpose. Two parabolic trough type collector arrays are shown here. The heart of the system is the concentrating collector whose cost would be about half that of flat plate and yet would collect almost twice as much energy per unit area. Such systems would be useful in textile industry, hotels, hostels and hospitals equally. The writer is a former professor
of Mechanical Engineering. |
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25 years of test tube babies
Alastair MacDonald always knew he was special. Everybody told him so. But it wasn’t until he was 10 years old that he figured out why. A news bulletin about the death of his Uncle Patrick with details about his friend Louise and her revolutionary birth were enough for the precocious youngster to piece together the puzzle. Uncle Patrick was Patrick Steptoe, one of the pioneers of in-vitro fertilisation (IVF), and his friend was Louise Brown, the world’s first test tube baby. Alastair was the second IVF baby in the world and the first boy conceived through the ground-breaking technology. They celebrated the 25th anniversary of IVF on July 26 with 1,000 other test tube babies at the Bourn Hall Clinic in Cambridge where Steptoe and his partner Professor Robert Edwards worked. In the 25 years since the birth of Brown and Alastair six months later, more than a million children around the world have been conceived through fertility techniques. The treatment pioneered by Steptoe and Edwards has enabled infertile couples to experience the joy of having a child. Their work also laid the groundwork for advances in science that were unimaginable a quarter of a century ago. Lurid stories of eggs harvested from aborted foetuses, the possibility of human womb transplants and the creation of hybrid male/female embryos dominated a recent European fertility conference and sparked criticism that science had gone mad. Peter Brinsden, the medical director of Bourn Hall where about 6,000 children have been born through assisted reproduction, said the stories were "vastly overblown" and overshadowed advances that have been made in fertility treatments over the past 25 years. Success rates for IVF have improved. More treatments are available and scientists are better at freezing embryos. But Brinsden believes the most spectacular achievement has been ICSI, intracytoplasmic sperm injection, in which a single sperm is injected into the egg. "That really has achieved the most spectacular results for a group of people (with sperm problems)," he said. No one knows what the next 25 years will bring, Brinsden hopes fertility specialists will get better at what they are already doing. "I have an ambition before I retire to be able to say to a couple sitting across the desk from me I can give you a 50-50 chance of having a live child." "If only we could get up to that sort of figure in the next five to 10 years I think that would be the single biggest advance from the patient’s point of view," he added. MacDonald is proud to have been one
of the first recipients of IVF and realises how very lucky she was.
The success rate for IVF today is about 27 per cent. It was much less
25 years ago. "Sometimes I can’t believe I was so, so lucky in
the very early days. Alastair was more than a miracle. Not just
because of the treatment but in every way. I always keep saying you
were absolutely meant. There was no way God didn’t want me to have
you." — Reuters |
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Tunable “photon copier” on a chip A research team at the University of California at Santa Barbara (UCSB) has for the first time incorporated on a single chip both a widely tunable laser and an all-optical wavelength converter, thereby creating an integrated photonic circuit for transcribing data from one colour of light to another. Such a device is key to realising an all-optical network. This research is being funded by a Defence Advanced Research Projects Agency (DARPA) Microsystems Technology Office (MTO) grant to push the boundary for photonic-circuit functional integration. Think about data transmission over the Internet in terms of a telephone call between Los Angeles and New York. What enables two people to talk is the "dedicated" line between them. On the Internet the long-distance transport of information between the two cities is via optical fibers or light pipes, which can move numerous colours of light over a single fiber at the same time with each colour representing a "dedicated" line for the transmission of data (i.e., wavelength division multiplexing [WDM]). Data moves between coasts through nodes of the Internet located in cities like Phoenix or Houston, where the capability is needed to switch information arriving on one fiber as orange photons to continue the next leg of their journey on another fiber as red photons because the channel for orange on that fiber is in use. Today, this switching from one colour to another has to be done by converting photons to electrons, switching electronically, and converting electrons back to photons. The new postage-stamp-size device is a tunable "photon copier," which eliminates electronics as the middleman. It is as if information on orange paper were being copied onto red paper. The information stays the same, but the colour of the paper on which it is conveyed is different. By that analogy the tunable laser supplies the red paper, and the wavelength converter functions as the copy-machine transcribing the information of the orange original to red. The tunable laser is able to supply a wide range of colours and hues to copy onto, and the wavelength converter is able to maintain or improve the quality of the image, a process called "regeneration". Past attempts to engineer photonic circuits
with tunable lasers and wavelength converters have met with limited success,
and the two components have heretofore lived on separate chips. Fabricating
them on the same indium phosphide platform and thereby integrating them
represents a technological breakthrough and greatly enhances performance and
commercial feasibility. |
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Orphaned star clusters roam the universe US and UK astronomers have discovered a population of previously unknown star clusters in what was thought to be the empty space between galaxies. Most galaxies are surrounded by tens, hundreds or even thousands of ancient star clusters, which swarm around them like bees around a hive. Our own Milky Way galaxy has about 150 of these "globular clusters", as they are called. Globular clusters are systems of up to a million stars compacted together by gravity into dense sphere-shaped groupings. Studies of globular clusters have provided many important insights over the years into the formation of their parent galaxies. The discovery of this new type of star cluster was made using images obtained last year with the Hubble Space Telescope and the giant 10-meter Keck Telescope on Mauna Kea, Hawaii. "We found a large number of ‘orphaned’ globular clusters," said Dr West. clusters are no longer held within the gravitational grip of galaxies, and seem to be wandering freely through intergalactic space like cosmic vagabonds." Although the lonely existence of such star clusters had been predicted for half a century, it is only now that astronomers have finally been able to confirm their existence. Dr West’s team published preliminary findings about its discovery in April this year, and is now presenting new results at the International Astronomical Union’s 25th General Assembly, being held in Sydney, Australia. "The new data from the Hubble
Space Telescope and Keck Telescope confirm our discovery, and are
providing new insights to the origin of these objects," said Dr
West. |
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UNDERSTANDING THE UNIVERSE Solid bodies have their molecules tightly packed. It is different in liquids. But when water is changed to solid ice, it takes more volume. Why? In solid state molecules are not all running around. They form friendships with their neighbours. They catch hold of their neighbours. Depending on their properties more than two can form a structure, whose shape and architecture depend on the form, number and strength of their bonds. These structures are called crystals. A crystal is a congregation that has an architecture very much like a building. Like any building, its volume can be greater than the total volume of the constituents, the bricks of which they are made. Some space between the bricks is mandatory if we have to call their gathering a building. Water ice is also crystalline. That is the reason for ice being lighter than water. How do some birds fly for one month without any rest? It is true that some birds fly long distances for their yearly migration. I am sure they prepare for this by storing enough food in the form of fat and protein. They also exercise to strengthen their pectoral muscles, very much like athletes preparing for a big tournament. They also plan and economise to
reduce energy consumption, by choosing favourable winds and drafts and
appropriate stop over points for rest, recuperation and stocking up.
For doing much of this they make use of their admirable system of
navigation, using stars and the sun besides landmarks on the ground. |
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New products & discoveries Laser beams out of cheap plastic Like poker chips, lasers may someday be moulded out of plastic by the millions. A new laser-making method takes a major step in that direction, its Austrian developers say. Lasers are devices that emit a coherent beam of light of a single wavelength. Their prices have been coming down over the years, but dirt cheap plastic ones could serve as the heart of mass-produced biomedical and environmental sensors and optical-telecommunications networks, the researchers say. What’s more, unlike the lasers currently available, plastic ones could be flexible. Manufacturers today rely on costly fabrication techniques for making the microchip lasers used widely in CD and DVD players and other gadgets. Those techniques require exacting procedures carried out in tightly controlled conditions and meticulously clean environments. In the July 17 Advanced Materials, Martin Gaal and Emil J.W. List of the Graz University of Technology and their colleagues describe a simpler method of making lasers by imprinting patterns into plastic under ordinary conditions. The Graz scientists had teamed up with researchers from AT&S, a circuit board maker in Leoben, Austria. Sea salt impact on climate While a breeze over the ocean may cool beach goers in the summertime, a new scientific study has revealed that tiny sea salt particles drifting into the atmosphere participate in a chemical reaction that may have impacts on climate and acid rain. The research, published in the July 3 online issue of Science Express, could have substantial implications for increasing the accuracy of climate models. The study by scientists at the Department of Energy’s Pacific Northwest National Laboratory and the University of California, Irvine indicates that sea salt plays an important role – but one previously little understood — in the chemistry of sulfur in the atmosphere. One form of sulfur – sulfur dioxide – is a byproduct of burning fossil fuels containing sulfur. It is also formed when naturally emitted sulfur-containing compounds react in the atmosphere. In the air, sulfur dioxide is converted to sulfuric acid, a major component of acid rain and a contributor to haze in the atmosphere. These haze particles can affect clouds, which play an important role in climate. For years climate experts have struggled to capture the effects of sulfur chemistry in climate models. The PNNL-UCI study provides a new understanding of sea salt’s role in atmospheric chemistry that will allow scientists to better predict and capture that information in models used to predict climate change. — Pacific Northwest National Laboratory How anthrax hits immune system Scientists have discovered how anthrax evades the immune system, a discovery that could lead to more effective treatments against the infectious disease. Lethal factor, one of three poisonous proteins in the bacterium, disables dendritic cells — which form a crucial part of the immune system — so they cannot launch an attack against the anthrax microbe. "This is the first study that demonstrates any interaction between bacillus anthracis (anthrax) and dendritic cells," said Dr Bali Pulendran of Emory University in Atlanta, Georgia, yesterday. "When dendritic cells are compromised, such as in our study... the innate immune system is unable to stimulate the immune response,thus permitting the microbe to spread unchecked," he added. The study was published in the science magazine Nature. Lethal factor and two other toxins, protective antigen and edema factor, increase the deadly potency of anthrax, which killed five people infected by tainted letters in a bioterrorism scare in the United States nearly two years ago. — Reuters Space-age tractors The world’s over-farmed soil is sick and has been rapidly getting sicker, but scientists say space-age, satellite-driven tractors are coming to the rescue. Heavy modern farm equipment is killing the soil through repeated compaction and tilling, which in turn worsens salinity that kills crops. But a new world of automatically steered tractors, guided by satellites, will allow them to run on pre-determined tracks and confine their impact on the soil to 15 per cent of farmed land. "It will revolutionise agriculture, I believe," said Jeff Tullberg, a University of Queensland academic and president of the International Soil Tillage Research Organisation (ISTRO). Australian technology allows satellite-guided field equipment to move to an accuracy of two centimetres, or less than an inch. U.S.-based farm equipment leader
Deere & Co also followed an early Australian lead to develop an
integrated tractor guidance system based on global positioning system
(GPS) satellite technology, accurate to centimetres. — Reuters |
Agro-based
industries cover a wide range of materials. In this industry energy is
used to heat products, water, air for drying and dehydration of
materials and to generate steam. These are the top energy consuming
industries and require a temperature under 100`degree celsius. In general, since
the process temperature is low, it is common to find the heat supplied
through a low pressure boiler producing steam at 177 degree celsius. It could be
coal or oil fired.
Certainly
it will decrease the agricultural and food processing needs of power
which is about 50% of the total power generated and improve the
environment from pollution. Whatever is produced in excess, could be
dried and stored.