Tuesday, August 21, 2007

A miracle material Or Frozen Smoke

A miracle material for the 21st century could protect your home against bomb blasts, mop up oil spills and even help man fly to Mars.

Aerogel, one of the world's lightest solids, can withstand a direct blast of 1 kilogram of dynamite and protect against heat from a blowtorch at more than 2,400 degrees Fahrenheit.

Scientists are working to discover new applications for the substance, ranging from the next generation of tennis rackets to super-insulated spacesuits for a manned mission to Mars.



It is expected to rank alongside wonder products from previous generations such as Bakelite in the 1930s and carbon fiber in the 1980s.

Mercouri Kanatzidis, a chemistry professor at Northwestern University in Evanston, Ill., said: "It is an amazing material. It has the lowest density of any product known to man, yet at the same time it can do so much. I can see aerogel being used for everything from filtering polluted water to insulating against extreme temperatures and even for jewelry."

Aerogel is nicknamed "frozen smoke" and is made by extracting water from a gel made from silica or another metal oxide, then replacing it with a gas such as carbon dioxide.

The result is a substance that is capable of insulating against extreme temperatures and of absorbing pollutants such as crude oil.

The first aerogel was invented by an American chemist on a bet in 1931, but early versions were so brittle and costly that it was largely consigned to laboratories.

It was not until a decade ago that NASA started taking an interest in the substance and putting it to a more practical use.

In 1999 the space agency fitted its Stardust space probe with a mitt packed full of aerogel to catch the dust from a comet's tail. It returned with a rich collection of samples last year.

In 2002 Aspen Aerogel, a company created by NASA, produced a stronger and more flexible version of the gel. It is now being used to develop an insulated lining in space suits for the first manned mission to Mars, scheduled for 2018.

Mark Krajewski, a senior scientist at the company, believes that an 18 mm (three-quarters of an inch) layer of aerogel would be sufficient to protect astronauts from temperatures as low as minus 200 degrees Fahrenheit.

"It is the greatest insulator we've ever seen," he said.

Aerogel is also being tested for future bombproof housing and armor for military vehicles. In the laboratory, a metal plate coated in 6 mm (a quarter of an inch) of aerogel was left almost unscathed by a direct dynamite blast.

It also has environmental credentials. Aerogel is described by scientists as the "ultimate sponge," with millions of tiny pores on its surface making it ideal for absorbing pollutants in water.

Kanatzidis has created a new version of aerogel designed to mop up lead and mercury from water. Other versions are designed to absorb oil spills.

He is optimistic that it could be used to deal with environmental catastrophes such as the Sea Empress spillage in 1996, when 72,000 tons of crude oil were released into the Irish Sea just off the coast of south Wales.

Aerogel is also being used for everyday applications. Dunlop, the sports-equipment company, has developed a range of squash and tennis rackets strengthened with aerogel, which are said to deliver more power.

Earlier this year Bob Stoker, 66, from Nottingham, central England, became the first Briton to have his property insulated with aerogel.

"The heating has improved significantly. I turned the thermostat down five degrees. It's been a remarkable transformation," he said.

Mountain climbers are also converts. Last year Anne Parmenter, a British mountaineer, climbed Mt. Everest using boots that had aerogel insoles, as well as sleeping bags padded with the material.

She said at the time: "The only problem I had was that my feet were too hot, which is a great problem to have as a mountaineer."

However, it has failed to convince the fashion world. Hugo Boss created a line of winter jackets out of the material, but had to withdraw them after complaints that they were too hot.

Although aerogel is classed as a solid, 99 percent of the substance is made up of gas, which gives it a cloudy appearance.

Scientists say that because it has so many millions of pores and ridges, if one cubic centimeter of aerogel were unraveled, it would fill an area the size of a football field.

Its nano-sized pores can not only collect pollutants like a sponge, but they also act as air pockets.

Researchers believe that some versions of aerogel, made from platinum oxides, could be used to speed up the production of hydrogen. As a result, aerogel may be used to make hydrogen-based fuels.
Posted by Ajay :: 5:11 PM :: 0 comments

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---------------oOo--------------- Dead Star Found.........

Astronomers have spotted a space oddity in Earth's neighbourhood - a dead star with some unusual characteristics.

The object, known as a neutron star, was studied using space telescopes and ground-based observatories.

But this one, located in the constellation Ursa Minor, seems to lack some key characteristics found in other neutron stars.

Details of the study, by a team of American and Canadian researchers, will appear in the Astrophysical Journal.

If confirmed, it would be only the eighth known "isolated neutron star" - meaning a neutron star that does not have an associated supernova remnant, binary companion, or radio pulsations.


Either Calvera is an unusual example of a known type of neutron star, or it is some new type of neutron star, the first of its kind
Robert Rutledge, McGill University
The object has been nicknamed Calvera, after the villain in the 1960s western film The Magnificent Seven.

"The seven previously known isolated neutron stars are known collectively as The Magnificent Seven within the community," said co-author Derek Fox, of Pennsylvania State University, US.

"So the name Calvera is a bit of an inside joke on our part."

The authors estimate that the object is 250 to 1,000 light-years away. This would make Calvera one of the closest neutron stars to Earth - and possibly the closest.

Neutron stars are one of the possible end points for a star. They are created when stars with masses greater than four to eight times those of our Sun exhaust their nuclear fuel, and undergo a supernova explosion.

This explosion blows off the outer layers of the star, forming a supernova remnant. The central region of the star collapses under gravity, causing protons and electrons to combine to form neutrons - hence the name "neutron star".

Data search

Robert Rutledge of McGill University in Montreal, Canada, originally noticed the object.

He compared a catalogue of 18,000 X-ray sources from the German-American Rosat satellite, which operated from 1990 to 1999, with catalogues of objects that appeared in visible light, infrared light, and radio waves.

Artist's impression of Swift, Nasa
Swift was launched to observe gamma-ray bursts
Professor Rutledge realized that a Rosat source, known as 1RXS J141256.0+792204, did not appear to have a counterpart at any other wavelength.

The group aimed Nasa's Swift satellite at the object in August 2006. Swift's X-ray telescope showed that the source was still there, and was emitting about the same amount of X-ray energy as it had during the Rosat era.

The Swift observations enabled the group to pinpoint the object's position more accurately, and showed that it was not associated with any known astronomical object.

The researchers followed up with the 8.1m Gemini North Telescope in Hawaii and a short observation by Nasa's Chandra X-ray Observatory.

Unusual properties

Exactly what type of neutron star Calvera is remains a mystery. According to Dr Rutledge, there are no widely accepted alternative theories to explain objects such as this that are bright in X-rays and faint in visible light.

"Either Calvera is an unusual example of a known type of neutron star, or it is some new type of neutron star, the first of its kind," said Dr Rutledge.

Calvera's location high above the plane of our Milky Way galaxy is also a mystery. The researchers believe the object is the remnant of a star that lived in our galaxy's starry disc before exploding as a supernova.

In order to reach its current position, it had to wander some distance out of the disc.

Posted by Ajay :: 5:07 PM :: 0 comments

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---------------oOo--------------- Interesting History

Next time you're washing your hands and the water temperature isn't just how you like it, think about how things used to be. Here are some facts about the 1500s.

Most people got married in June because they took their yearly bath in May and still smelled pretty good by June. However, they were starting to smell, so brides carried a bouquet of flowers to hide the body odor.

Baths consisted of a big tub filled with hot water. The man of the house had the privilege of the nice clean water, then all the other sons and men, then the women and finally the children -- last of all the babies. By then the water was so dirty you could actually lose someone in it. Hence the saying, "Don't throw the baby out with the bath water."

Houses had thatched roofs -- thick straw -- piled high, with no wood underneath. It was the only place for animals to get warm, so all the dogs, cats and other small animals (mice, bugs) lived in the roof. When it rained it became slippery and sometimes the animals would slip and fall off the roof -- hence the saying "It's raining cats and dogs."

There was nothing to stop things from falling into the house. This posed a real problem in the bedroom where bugs and other droppings could really mess up your nice clean bed. Hence, a bed with big posts and a sheet hung over the top afforded some protection. That's how canopy beds came into existence.

The floor was dirt. Only the wealthy had something other than dirt, hence the saying "dirt poor."

The wealthy had slate floors that would get slippery in the winter when wet, so they spread thresh (straw) on the floor to help keep their footing. As the winter wore on, they kept adding more thresh until when you opened the door it would all start slipping outside. A piece of wood was placed in the entranceway, hence, a "thresh hold."

In those old days, they cooked in the kitchen with a big kettle that always hung over the fire. Every day they lit the fire and added things to the pot. They ate mostly vegetables and did not get much meat. They would eat the stew for dinner, leaving leftovers in the pot to get cold overnight and then start over the next day. Sometimes the stew had food in it that had been there for quite awhile. Hence the rhyme, "peas porridge hot, peas porridge cold, peas porridge in the pot nine days old."

Sometimes they could obtain pork, which made them feel quite special. When visitors came over, they would hang up their bacon to show off. It was a sign of wealth that a man "could bring home the bacon." They would cut off a little to share with guests and would all sit around and "chew the fat."

Those with money had plates made of pewter. Food with a high acid content caused some of the lead to leach onto the food, causing lead poisoning and death. This happened most often with tomatoes, so for the next 400 years or so, tomatoes were considered poisonous.

Most people did not have pewter plates, but had trenchers, a piece of wood with the middle scooped out like a bowl. Often trenchers were made from stale bread which was so old and hard that they could be used for quite some time. Trenchers were never washed and a lot of times worms and mold got into the wood and old bread. After eating off wormy, moldy trenchers, one would get "trench mouth."

Bread was divided according to status. Workers got the burnt bottom of the loaf, the family got the middle, and guests got the top, or "upper crust."

Lead cups were used to drink ale or whiskey. The combination would sometimes knock them out for a couple of days. Someone walking along the road would take them for dead and prepare them for burial. They were laid out on the kitchen table for a couple of days and the family would gather around and eat and drink and wait and see if they would wake up. Hence the custom of holding a "wake."

England is old and small and the local folks started running out of places to bury people. So they would dig up coffins and would take the bones to a "bone-house" and reuse the grave. When reopening these coffins, 1 out of 25 coffins were found to have scratch marks on the inside and they realized they had been burying people alive. So they thought they would tie a string on the wrist of the corpse, lead it through the coffin and up through the ground and tie it to a bell. Someone would have to sit out in the graveyard all night (the "graveyard shift") to listen for the bell; thus, someone could be "saved by the bell" or was considered a "dead ringer."

And that's the truth. . . (who ever said that History was boring)?

Posted by Ajay :: 9:52 AM :: 0 comments

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---------------oOo--------------- Mice Born From Eggs

A surprising number of animals can reproduce via a process called parthenogenesis, in which females produce viable and fertile offspring without getting a male involved. Although this is rarely the reproductive method of choice, even vertebrates such as sharks and lizards have reproduced without males when sexual reproduction wasn't an option in zoos and aquariums. Parthenogenesis doesn't seem to be an option in mammals, though, as both male and female mammals modify the genomes in their germ cells in ways that cause lasting changes in their expression, a process termed imprinting. But a research team has now figured out a way of avoiding these problems, and have created mice with two mothers, and no involvement with a father.

The researchers built this breakthrough on two pieces of knowledge. The first is that cells early on the path to oocyte (egg cell) development haven't been imprinted yet. The second is that researchers have identified a small number of areas in the genome that undergo opposite imprinting in the two sexes. The researchers generated mice carrying deletions of two of the imprinted areas, and then isolated early oocytes that had not started the imprinting process from these mice.

These cells could be fused with a normal oocyte, creating a cell with a normal diploid genome. When those cells were activated to divide, they produced apparently normal early embryos. Once implanted into female mice, the embryos survived to adulthood at rates roughly comparable to those produced by in vitro fertilization. The biggest difference appears to be a reduction in their growth rates—adults wound up 20 percent smaller than normal mice. This isn't much of a surprise, given that imprinting is one of the ways that males and females compete for providing the appropriate amount of resources for their offspring.

It's not clear whether these mice are necessarily going to be useful for any specific application, but they tell us two things. One is that there appear to be only two regions of the genome that are imprinted in a way that's essential for the control of embryonic development, which should greatly simplify the study of that topic. The second is that the lack of a male contribution has been proposed to be a key reason for the low success rates of cloning and various forms of somatic cell nuclear transplants. The results indicate that there's nothing magical provided by the male other than the properly imprinted chromosomes.

Posted by Ajay :: 9:49 AM :: 0 comments

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