贵阳工业吸尘器(黄石工业吸尘器厂家) (今日更新中)

WASHINGTON, July 12 (Xinhua) -- Two U.S. astronauts stepped out the International Space Station on Tuesday to retrieve a failed ammonia pump, which is the last spacewalk of the shuttle era, NASA announced.Space station astronauts Mike Fossum and Ron Garan completed the six-hour, 31-minute spacewalk at 3:53 p.m. EDT (1953 GMT). The duo retrieved a pump module from an external stowage platform on station and store it in shuttle Atlantis' cargo bay for return to Earth.The pump module failed in 2010, shutting down half of the space station's cooling system. Engineers will evaluate the module to determine the cause of the failure and plan to refurbish it for use as a spare.The astronauts also attached a Robotic Refueling Module experiment to the space station, which aims to test technologies for repairing and refueling satellites in space.It was the 249th spacewalk by U.S. astronauts and the 160th spacewalk in support of space station assembly and maintenance, totaling 1009 hours, nine minutes.Atlantis lifted off on Friday morning from Kennedy Space Center in Florida, on the 135th and final flight in NASA's shuttle program. Its return to the earth later this month will mark the end of the 30-year shuttle program.

WASHINGTON, Aug. 31 (Xinhua) -- Astronomers using NASA's Chandra X-ray Observatory discovered the first pair of supermassive black holes in a spiral galaxy similar to the Milky Way, NASA announced Wednesday.Approximately 160 million light years from Earth, the pair is the nearest known such phenomenon.The black holes are located near the center of the spiral galaxy NGC 3393. Separated by only 490 light years, the black holes are likely the remnant of a merger of two galaxies of unequal mass a billion or more years ago.Both of the supermassive black holes are heavily obscured by dust and gas, which makes them difficult to observe in optical light. Because X-rays are more energetic, they can penetrate this obscuring material. Chandra's X-ray spectra show clear signatures of a pair of supermassive black holes."If this galaxy weren't so close, we'd have no chance of separating the two black holes the way we have," said Pepi Fabbiano of the Harvard-Smithsonian Center for Astrophysics, who led the study that appeared Wednesday in on-line issue of the journal Nature. "Since this galaxy was right under our noses by cosmic standards, it makes us wonder how many of these black hole pairs we've been missing."Previous observations in X-rays and at other wavelengths indicated that a single supermassive black hole existed in the center of NGC 3393. However, a long look by Chandra allowed the researchers to detect and separate the dual black holes. Both black holes are actively growing and emitting X-rays as gas falls towards them and becomes hotter.When two equal-sized spiral galaxies merge, astronomers think it should result in the formation of a black hole pair and a galaxy with a disrupted appearance and intense star formation. A well-known example is the pair of supermassive black holes in NGC 6240, which is located about 330 million light years from Earth.However, NGC 3393 is a well-organized spiral galaxy, and its central bulge is dominated by old stars. These are unusual properties for a galaxy containing a pair of black holes.

MOSCOW, Aug. 7 (Xinhua) -- A state of emergency has been imposed in a district in the Krasnodar Region in south Russia amid an out break of the African swine fever, the regional emergencies center said on Sunday.The emergencies center told local reporters that the African swine fever virus (ASFV) was found in a private farm where 15 pigs died of the disease, but the source of the infection is still unclear.Local authorities said some 12,000 pigs in and around the Krylovskaya village, some three km away from the private farm, are being culled, 50 of which have already died of the ASFV in recent days.In April, the regional emergencies has temporarily declared a state of emergency in the Labinsky district in the region, as the ASFV was found at a livestock farm. 85 pigs were culled at the farm.

SAN FRANCISCO, June 28 (Xinhua) -- Google on Tuesday rolled out a new social networking service named "Google+", a long awaited move of the Internet search giant to crack the industry's social trend dominated by Facebook.Unlike Facebook, Google said that the project is designed for sharing with small groups like college roommates and parents. " Today's online services turn friendship into fast food, wrapping everyone in 'friend' paper," Google said in a blog post announcing the new service.Other Google+ features include Sparks, which gathers articles and videos on topics of interests or hobbies; and Hangouts, which allows users join live multi-person video chat.There is also a mobile version of Google+ for smartphones running Google's Android operating system, which enables multi- person text message chats and instant upload of photos from the phone.The Google+ project is currently in field trial and by invitation only. Users can select people from their Gmail contacts and organize them into different groups.Google+ is expected to test whether Google could come back from its past frustration in social networking, such as Buzz, a social networking and messaging too integrated into its Gmail service. Some of Google Buzz's features have been widely criticized for privacy concerns.Market research data show that Facebook has surpassed Google in terms of time spent on each site, a fact that advertisers attach importance to.According to Internet market research company comScore, including YouTube, 180 million people visited Google sites in May, compare to 157.2 million on Facebook. However, Facebook users looked at 103 billion pages and spent an average of 375 minutes on the site, while Google users viewed 46.3 billion pages and spent 231 minutes.In April, Google CEO and co-founder Larry Page reportedly sent out a company-wide memo alerting employees that 25 percent of their annual bonus will be tied to the success or failure of Google's social strategy in 2011.

BEIJING, July 19 (Xinhuanet) -- Amazon on Monday launched its Kindle textbook rental service, which allows students to rent "tens of thousands of textbooks", according to Los Angeles Times.The e-book textbook rental service will help students save as much as 80 percent on some titles.Amazon said that students can now rent textbooks from 30 to 360 days and can either rent them again or purchase them once the rental period is up."Students tell us that they enjoy the low prices we offer on new and used print textbooks. Now we're excited to offer students an option to rent Kindle textbooks and only pay for the time they need—with savings up to 80 percent off the print list price on a 30-day rental," Dave Limp, vice president of Amazon Kindle said, according to PC Magazine.Rentals can be read on Amazon's Kindle eReaders, and Kindle apps for PCs, as well as smartphones and tablet computers running Apple's iOS, Microsoft Windows Phone 7 and Google's Android operating system.Rentals also have a clear advantage over physical copies that students' notes and highlighted content will be stored in the Amazon Cloud, and can be accessed if students rent the books again or buy at a later time.

来源：资阳报