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BEIJING, Sept. 23 (Xinhua) -- A defunct U.S. satellite is expected to crash down to Earth Friday, with nobody knowing where or when exactly it will hit. This was avoidable, a Chinese expert said Thursday.Pang Zhihao, a researcher from the Chinese Research Institute of Space Technology, told Xinhua that the crash could have been avoided had the satellite been put into a higher orbit, or manipulated to drop in the South Pacific when it had abundant fuel. It would pose no threat to Earth if these measures had been taken.NASA's tumbling, 5,900 kg Upper Atmosphere Research Satellite, or UARS, is the first of such man-made space vehicles that have been launched into outer space according to the agency's Mission to Planet Earth. The mission was launched in the 1990s.The mission is designed to provide data for better understanding Earth's upper atmosphere and the effects of natural and human interactions on the atmosphere.The satellite was deactivated in 2005 as it ran out of fuel and was left orbiting Earth like a big piece of space junk.There are other cases of defunct satellites. The European Space Agency said earlier its observation satellite ERS-2 has run out of fuel and is deorbiting. It would therefore also crash sooner or later.Pang said all countries which are operating space vehicles should take care of their own spacecrafts so that they won't pose any danger.The expert also said that the public need not worry too much.Pang said most spacecrafts will be incinerated upon re-entering Earth's atmosphere, and the debris will mostly likely fall into the ocean or hit an uninhabited area. In addition, a debris tracker is able to give a comparatively accurate prediction where the craft will fall about two hours before it hits Earth, giving residents, if there are any, time to evacuate.He added that there are several ways to minimize the threat of decommissioned spacecrafts, like putting them into higher orbits and crashing them into designated waters.Scientific progress would possibly bring about more ways of dealing with tumbling satellites. Scientists have already been trying to build spacecrafts with degradable materials so that they can self-destruct when re-entering Earth's atmosphere.

WASHINGTON, Sept. 26 (Xinhua) -- Older people with low blood levels of vitamin B12 markers may be more likely to have lower brain volumes and have problems with their thinking skills, according to researchers at Rush University Medical Center in Chicago.The results of the study will be published Tuesday in Neurology, the medical journal of the American Academy of Neurology.Foods that come from animals, including fish, meat, especially liver, milk, eggs and poultry are usual sources of vitamin B12.The study involved 121 older residents of the south side of Chicago over the age of 65. They had blood drawn to measure levels of vitamin B12 and B12-related markers that can indicate a B12 deficiency. The same subjects took tests measuring their memory and other cognitive skills.An average of four-and-a-half years later, MRI scans of the participants' brains were taken to measure total brain volume and look for other signs of brain damage.Having high levels of four of five markers for vitamin B12 deficiency was associated with having lower scores on the cognitive tests and smaller total brain volume."Our findings definitely deserve further examination," said Christine Tangney, associate professor at Rush University Medical Center and lead author of the study. "It's too early to say whether increasing vitamin B12 levels in older people through diet or supplements could prevent these problems, but it is an interesting question to explore. Findings from a British trial with B vitamin supplementation are also supportive of these outcomes."On the cognitive tests, the scores ranged from -2.18 to 1.42, with an average of 0.23. For each increase of one micromole per liter of homocysteine -- one of the markers of B12 deficiency -- the cognitive scores decreased by 0.03 standardized units or points.Tangney noted that the level of vitamin B12 itself in the blood was not associated with cognitive problems or loss in brain volume. "Our findings lend support for the contention that poor vitamin B12 status is a potential risk factor for brain atrophy and may contribute to cognitive impairment," said Tangney.

SAN FRANCISCO, Aug. 22 (Xinhua) -- Hewlett-Packard's tablet TouchPad has become the hottest consumer electronics device on Monday after HP launched a fire sale for the discontinued product line over the weekend."It was like a stampede and they went quick," a Best Buy employee in San Diego told technology news website Betanews, describing the line waiting to buy TouchPad. He said the discontinued tablet was sold out five minutes after the store opened.The device is also getting snatched up at a lighting speed online and increasingly difficult to find.The TouchPad is no longer listed on Bestbuy.com in the United States, which last week was reportedly sitting on 270,000 unsold TouchPads and was hoping HP would buy them back.On Amazon, TouchPad tops the world's largest online retailer's electronics sales list, beating out the electronic reader Kindle and iPod touch.Last Thursday, HP announced that it will completely shut down its webOS operations, specifically the TouchPad tablet and webOS phones.The 16 GB TouchPad currently is only 99.99 U.S. dollars, compared to the original price of 399 dollars. The 32 GB model, which used to be 485.99 dollars, is now priced at 149.99 dollars.

BEIJING, July 6 (Xinhua) -- The Ministry of Health has issued a national standard on compound food additives to better regulate the production and use of such additives and ensure food safety.Compound food additives, which are designed to improve food quality or assist in food processing, should be used sparingly in food products, according to the standard the ministry issued Tuesday.Titled the General Rule on Compound Food Additives, the standard stipulates that each of the ingredients used for making compound food additives, which are a mix of two or more single food additives, should meet national standards concerning food safety.No chemical reaction should occur and no new compounds should be generated during the production process of compound food additives, according to the standard.Compound food additives producers should clarify limits of the amounts of harmful substances, such as lead and arsenic, in their products and take measures to control the levels of harmful substances, according to the standard, which will come into effect on Sept. 5 this year.

BEIJING, Aug. 22 (Xinhuanet) -- Researchers have discovered how a human egg captures an incoming sperm for fertilization, paving the way to help couples suffering from infertility, according to media reports on Monday.An international team of researchers found that a sugar chain known as the sialyl-lewis-x sequence (SLeX) makes the outer coat of the egg “sticky,” which has proven to be helpful in binding the egg and the sperm.As a result, this observation has filled in a huge gap in the understanding of fertility and provides hope for ultimately helping couples who currently cannot conceive.Scientists and doctors know that a sperm identifies an egg when proteins on the head of the sperm match and bind to a series of specific sugars in the egg’s outer coating. With a successful match of proteins, the outside surfaces of the sperm and egg then bind together before merging, which is then followed by delivery of sperm’s DNA into egg.To identify this molecules, the researchers used ultra-sensitive mass-spectrometric imaging technology to observe and identify which molecules are most likely to be key in the binding process.They experimented with a range of synthesised sugars in the laboratory and found that it is SLeX that specifically binds sperm to an egg.According to the World Health Organisation, infertility affects about 15 percent of reproductive-aged couples around the world and almost one in every seven couples in Britain has problems conceiving a child for various reasons.