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Official Weibo: http://weibo.com/u/3476904471 大家好!胖胖翔来了!今天的科技文有负面新闻，也有与珠宝矿石有关，跨度较大！感谢大家的支持，我要继续再战TOEFL～
Part I：Speaker Voyager 1 Is Officially out There Voyager 1's own record of the plasma vibrations in its vicinity conclusively show that it has reached the space between the stars. John Matson reports Transcript hided
This time it’s really gone. Previous claims have been made, but NASA says that after a 35-year journey Voyager 1 has indeed reached interstellar space. And here’s the evidence: [SOUND] I’ll tell you what that sound is in a moment. It appears that the spacecraft left the sun’s heliosphere more than a year ago. In August 2012, Voyager registered a drop in charged particles emanating from the sun. At the same time it was hit with higher levels of interstellar cosmic rays. But in the absence of corroborating evidence from plasma or magnetic field measurements, Voyager scientists were not convinced that Voyager 1 had truly departed. But in March 2012, the sun belched a big batch of plasma. The reverberation from that eruption took a year to reach Voyager. From the vibration of plasma in Voyager’s vicinity, scientists were able to measure the density of the plasma. That’s what you heard earlier: Voyager’s record of seven months of plasma vibrations condensed to a few seconds. [Donald Gurnett et al., In Situ Observations of Interstellar Plasma with Voyager 1, in Science] And that data enabled NASA to conclude that the spacecraft’s environs indeed now appear to be the stuff between stars. Cold, dark and very far away. —John Matson Source: http://www.scientificamerican.com/podcast/episode.cfm?id=voyager-1-is-officially-out-there-13-09-16
Part II：Speed
Article 2
【Time 2】 Oxygen shapes growth of graphene Number of atoms on copper surface changes size and rate of material's crystal development
Graphene, an atom-thick supermaterial, has captured the attention of scientists and the public because of its humble chemical makeup and remarkable properties. But when trying to make uniform crystals of the carbon material, researchers don’t always get what they expect.
The crystalline differences could come as a result of oxygen, Yufeng Hao of University of Texas at Austin and colleagues report October 24 in Science. The scientists found that larger graphene crystals with branched edges grew faster on copper surfaces exposed to oxygen for longer time periods. Copper surfaces with fewer oxygen atoms sprouted smaller, more compact graphene crystals with sharp edges.
Controlling the oxygen exposure, along with other variables such as temperature and pressure, of the copper surfaces could allow scientists to grow larger, more uniform graphene crystals, which may work better in electronic devices and other applications.
字数[139] Source: https://www.sciencenews.org/blog/science-ticker/oxygen-shapes-growth-graphene Mercury contamination in California to last 10,000 years Toxic remnants of gold rush will seep into San Francisco area waterways for millennia
MERCURY RUSH Banks that line Northern California’s Yuba River contain mercury left over from the California Gold Rush. A new study predicts that the toxic metal will continue to contaminate the region’s waterways for more than 10,000 years.
California’s gold rush ended more than a century ago, but the contamination it caused will last thousands of years, a new analysis shows.
Some hydraulic gold mining processes use the toxic metal mercury to separate gold from gravel. In the mid-1800s, gold mining released more than a cubic kilometer of mercury-laden sediments into Northern California’s Sierra Nevada foothills. The sediments fanned out and inundated rivers that flow into the San Francisco Bay. Researchers estimate that 90 percent of the mercury is still trapped within the sediments.
To understand how flooding and erosion may trigger future releases of the poison, researchers led by Michael Bliss Singer of the University of St. Andrews in Scotland measured mercury levels in sediments at 105 locations upstream of the bay.
Drawing on historical flood data to predict sediment flow, the team reports October 28 in the Proceedings of the National Academy of Sciences that the mining sediments will continue to release mercury into waterways over at least the next 10,000 years. As climate change intensifies the area’s rainstorms, the researchers predict, the flood-driven discharges should become more frequent.
字数[221] Source: https://www.sciencenews.org/article/mercury-contamination-california-last-10000-years
Mexican University Lifts Sanctions in Misconduct Case
MEXICO CITY—The National Autonomous University of Mexico (UNAM) here has lifted sanctions imposed on microbiologists Mario Soberón and Alejandra Bravo after a misconduct investigation. The husband-and-wife team at the university’s Institute of Biotechnology (IBt) was found to have manipulated images in 11 published papers. IBt today released a memo outlining its view of the case and calling for UNAM—widely viewed as Mexico’s most important university—to establish guidelines for handling misconduct allegations in the future.
The allegations against Soberón and Bravo involved papers on Bacillus thuringiensis (Bt) toxins, which are used in engineered crops to target insect pests. After IBt launched an internal investigation, Bravo and Soberón acknowledged having modified the images, says Carlos F. Arias, IBt’s director at the time. “They insisted that [these] were merely ‘cosmetic’ modifications,” he says—for example, erasing a line on a Western blot to make their conclusions clearer. Bravo and Soberón declined an interview request from ScienceInsider.
In the fall of 2012, an external committee convened by IBt concluded that modifications in at least two of the 11 articles were “inappropriate and categorically reprehensible,” according to a memo circulated publicly by IBt. But the panel found that the alterations did not constitute scientific fraud because they did not affect the papers’ central conclusions. The commission advised against retracting the papers. Instead, it recommended sanctions, which IBt imposed: asking Soberón to resign as head of UNAM’s molecular microbiology department (he complied); demoting Bravo from an “academic leader” to an “associate researcher;” and forbidding the pair from accepting new graduate students for 3 years.
字数[261]
【Time 5】
The Mexican press has followed the saga closely, with some opinion columnists applauding IBt’s handling of the case and others defending Soberón and Bravo against what they see as unjust allegations. In a recent op-ed for the newspaper El Universal, Juan Ramón de la Fuente, who was dean of UNAM between 1999 and 2007 and remains a powerful voice in the Mexican scientific community, held up Bravo and Soberón as “victims of excessive suspicion” by scientists who “envy” their success.
In the latest twist, UNAM’s ombudsman Jorge Carmona has lifted the sanctions, citing irregularities in IBt’s investigation. According to Carmona, the problems included the presence of the complainant on the internal IBt committee that first evaluated the case, a lack of adequate opportunities for Soberón and Bravo to argue their position, and a breach of confidentiality that led to rumors and press reports that Carmona says may have unduly damaged the researchers’ reputations. He also says the committee convened by his office was concerned that the punishment was too severe for image manipulation. “It’s not exoneration,” Carmona says. Rather, his office considers the pair’s punishment “fulfilled” after 1 year.
Next on the agenda for UNAM is creating a system for handling misconduct allegations. “In the event that there’s a complaint, there’s no defined way to proceed. So what do we do?” says Agustín López Munguía, IBt’s academic secretary at the time the allegations against Soberón and Bravo arose. Carmona says that UNAM’s general consul is drafting new regulations outlining how the university should handle alleged ethical lapses.
字数[257] Source: http://news.sciencemag.org/latin-america/2013/10/mexican-university-lifts-sanctions-misconduct-case
Article 5 【Time 6】 Gold Mining and the Damage Wrought
There’s a gold rush going on in the Peruvian state of Madre de Dios, resulting in deforestation, runoff, and, as Science reported last month, mercury pollution. But because most of this mining is small-scale, clandestine, and illegal, researchers have had a hard time calculating its true extent. Now, a team of scientists has collaborated to accurately map Madre de Dios’s gold mines in space and time. The image above, created with new high-resolution satellite mapping techniques, shows the spread of gold mining along the Madre de Dios River between 1999 and 2012. Pink represents mines present before 1999; blue and green illustrate the spread during the middle of the 2000s; and yellow, orange, and red capture the mining that has sprung up since 2008. In 13 years, small-scale mining operations increased by 600% and the amount of land in the state affected by gold mining quadrupled, the researchers report online today in the Proceedings of the National Academy of Sciences (PNAS). Today, gold mining gobbles up an average of 6145 hectares of rainforest per year in Madre de Dios—more than three times the rate before the 2008 financial crisis drove up the demand for gold. And as another paper in PNAS this week shows, it’s nearly impossible to clean up after gold mining: Mercury pollution from the 19th century California gold rush will likely persist in the environment for more than 10,000 years.
字数[234] Source: http://news.sciencemag.org/earth/2013/10/scienceshot-gold-mining-and-damage-wrought?rss=1
Part III： Obstacle How to Find a Diamond in Arkansas
A teenage visitor to Crater of Diamonds State Park takes home a 3.85-carat gem.
As teenager Tana Clymer discovered this month, watching where you step can really pay off—especially on a certain patch of volcanic soil in southwest Arkansas. Visitors to Crater of Diamonds State Park in Murfreesboro have found more than 30,000 diamonds since the park opened in 1972.
No sophisticated tools or techniques are required; the two biggest finds so far this year were made by kids. To find out more about about this unusual state park, we spoke with Waymon Cox, an interpreter at Crater of Diamonds since 2004.
Tell us about the latest big find. It was on October 19. A girl from Oklahoma City and her family were out about two hours, digging and sifting with screens and buckets and shovels. They weren't having any luck, so she decided to just start "surface searching," looking on top of the ground. She saw what she thought was a candy wrapper, until she touched it. It turned out to be a 3.85-carat yellow diamond.
Does she get to keep it? Yep, that's how it works here: finders keepers. You just have to pay the entry fee ($7 adults, $4 ages 6-12; equipment rental extra).
Most people associate diamonds with Africa, not Arkansas. How did they get there? There was a volcanic eruption about 100 million years ago that created an 83-acre crater here. That eruption brought rocks and minerals from the Earth's mantle to the surface, and over time erosion has removed a lot of the lighter soil and left behind the heavier stuff, including diamonds and other gemstones. Geologists had suspected there might be diamonds because the soil looked greenish, which meant it was a kind of volcanic soil called lamporite tuff, similar to the soil of diamond fields in South Africa. But they took some samples in 1889 and didn't find any diamonds.
So who did find the first sparkler? The first diamond was discovered by a local farmer, John Wesley Huddleston, shortly after he purchased the land in 1906. Nobody knows the exact story. It's become the stuff of legend, but here's one version: He was crawling around on his hands and knees when he saw a glittering pebble. He took it to a nearby creek and washed it in a gold-mining pan. The glittering flakes floated away and turned out to be mica, not gold, but in the bottom of his pan he saw a smooth, rounded stone that he said shone in his eyes like fire. He took it to the bank in Murfreesboro, and on the way he actually found another diamond on the surface of his road. The bank teller offered him 50 cents for the stones, which he flatly refused. The bank's president sent the stones to a jeweler in Little Rock, then eventually to Tiffany's, where a jeweler confirmed that these were two gem-quality diamonds. There was a flood of prospecting in the area once word got out. Huddleston wasn't interested in diamond mining himself, so he sold the land to a group of investors for $36,000.
Was that a lot back then? Yes, it was like being a millionaire. Huddleston expected it would take care of his family for the rest of their lives—though he actually ended up losing most of it in a series of bad investments. And nobody really got rich mining diamonds here. There were several commercial mining ventures, but none of them had much success, and by the 1950s there were two competing "pay to dig" tourist attractions here. They were sold to the same company in the late 1960s, which sold the land to the state a few years later. The park opened in 1972. Are there any diamonds from the area that really stand out? The largest diamond ever found in the U.S., a white gem named the Uncle Sam, was found here in 1924. It was 40.23 carats, which is basically the size of a gumball. And in the 1950s, a woman found a 15.33-carat diamond. What about nowadays? How does Clymer's find compare with others in the park's history? Hers was the second-largest this year; a 12-year-old boy from North Carolina found a five-carat one in July. Clymer said hearing about that was actually what made her want to come try her luck. This year, we've had 400 diamonds found so far, which is about the same as last year, when we had 530 total. Some years it's more. Most are very small, about the size of a kitchen match head, but each year we do have one or two over five carats. Are the diamonds very valuable? Some are; it depends on the "4 C's" of diamonds: color, clarity, carat, and cut. There's also a fifth 'c' for us, which is "country"—people come to search here specifically because it's so unique to have an American diamond. Most people we never hear from again, so we don't know what their stones were valued at. But recently a woman told us she had [a park diamond] cut and graded and it was valued at nearly $22,000. The Strawn-Wagner diamond was found in 1990 by local resident Shirley Strawn. It was a 3.03 carat in the rough. She saved her money up, had it cut into a perfect 1.09 carat, round, brilliant shape. It was the only perfect diamond that's ever been graded by the American Gem Society: ideal cut, clarity, and color, just flawless. She sold it to the park for $36,000 that was raised by donations, and now it's on permanent display in our visitor's center. Have you ever found any? I've found two very, very small ones—one I actually found during a demonstration I was doing for tourists. Usually I'm too busy to spend my days off searching here. But when people bring these large ones up to the discovery center, you do catch a bit of diamond fever. Is the park ever going to run out of diamonds? Not any time soon. The land was tested by a private mining company in the 1990s. They drilled down 600 feet, and they ran out of drill before they ran out of soil, so there's quite a lot of it. Those tests determined that we had the eighth-largest diamond field in the world in terms of surface area. What we call the "pipe" of the volcanic crater is a little over 80 acres, and about 37.5 acres of that is our search area. Why did commercial mining ventures there fail? I mean, how can you own a diamond field and not strike it rich? Well, there's a minimum carat yield needed for a profitable mine. The diamonds here were just too small and too far between compared to the African mines. And you don't necessarily need to mine to find these diamonds. It might surprise people to know that because of the nature of the geology and millions of years of erosion, most of the diamonds tend to be on the surface. So even while commercial mines were digging deep and not finding much, people who were just walking along, looking carefully at the surface, were finding diamonds. There must be some sort of life lesson in that. Something like the tortoise and the hare, yeah. The slow and steady approach wins.
字数[1213] Source: http://news.nationalgeographic.com/news/2013/10/131028-crater-diamond-arkansas-park-geology/?source=hp_dl4_news-teenager-diamond_20131029
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发表于 2013-10-29 23:53:27
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