nano 2007-12-22 06:36
2007年度”自然“杂志编委推荐的非Nature上的热点文章
【纳米科技世界快讯】As an end of the year round-up, we asked [i]Nature[/i]'s editors to nominate favourite papers published elsewhere this year Molecular biology: ZA#{}8y
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[list][*][b]Stem cell success[/b][/list]K'N9v&Z3IZl4k$~
[size=4][url=http://dx.doi.org/10.1016/j.cell.2007.11.019][color=#0000ff]Cell 131, 861–872 (2007)[/color][/url]; [url=http://dx.doi.org/10.1038/nbt1374][color=#0000ff]Nature Biotechnol. doi:10.1038/nbt1374 (2007)[/color][/url]; [url=http://dx.doi.org/10.1126/science.1151526][color=#0000ff]Science doi:10.1126/science.1151526 (2007)[/color][/url][/size]
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In 2006, Shinya Yamanaka and Kazutoshi Takahashi of Kyoto University in Japan successfully prepared stem-like cells, which can develop into almost any of the body's cell types, from adult mouse skin cells. The technique involved 'reprogramming' the skin cells by introducing four specific genes using retroviruses, and provided a means of obtaining stem-like cells without using eggs or destroying embryos.
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In 2007, Yamanaka and his colleagues went one better, successfully reproducing the experiment with human skin cells. The recipe works because the additional genes function as high-level regulators, turning on other genes and thereby setting off a cascade of intracellular changes.
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Later, the group reported that it had eliminated the cancer-causing gene c-[i]Myc[/i] from the list of introduced genes, a research boon along the path towards patient-matched stem-cell therapies. James Thomson of the University of Wisconsin-Madison and his co-workers also published a c-[i]Myc[/i]-free method.
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[list][*][b]Cancer: Aid to resistance[/b][/list]
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[size=4][url=http://dx.doi.org/10.1126/science.1141478][color=#0000ff]Science doi:10.1126/science.1141478 (2007)[/color][/url][/size]
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The drug gefitinib is at first an effective treatment for certain types of lung cancer, but most cancers become resistant to it. New research provides insight into one mechanism by which this happens.j5]?$Dz2c{#~"_C$E
Gefitinib inhibits an enzyme known as EGFR kinase, and around half of the resistance cases are due to mutations in this target. Among the rest, Pasi Jänne of the Dana-Farber Cancer Institute in Boston, Massachusetts, and his colleagues found that some resistant cells showed increased expression of a tyrosine-kinase receptor named MET. This activates the same signalling pathway that EGFR kinase triggers — a pathway that mediates cell survival.O+vq}[L6X$x\L
The researchers found that the MET gene had multiplied rather than mutated, and that inhibiting MET restored the cells' sensitivity to gefitinib.&`5|1w
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[url=http://www.nature.com/nature/journal/v450/n7173/full/4501130a.html#top][color=#0000ff][/color][/url][list][*][b]Mathematics: The 248th dimension[/b][/list][url=http://www.nanost.net/bbs/forum-84-1.html][img]http://www.nature.com/nature/journal/v450/n7173/images/4501130a-i1.0.jpg[/img][/url]P. MCMULLEN/AM. INST. MATH.
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[url=http://www.liegroups.org/][color=#0000ff]http://www.liegroups.org[/color][/url]
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It took 77 hours for a supercomputer to crunch its way through the calculations set out by Jeffrey Adams, of the University of Maryland in College Park, and his co-workers. The result was a matrix with 205 billion entries that describes the 248 axes of symmetry and 57-dimensional surface of a mathematical structure called [i]E[/i]8 (represented right).&LP.W
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[i]E[/i]8 is the largest and most complicated object of smooth symmetry, known to mathematicians as an 'exceptional Lie group'. The team's main challenge was to work out how to condense the sums required so as to make them small enough for a supercomputer to handle, a feat achieved by invoking the 'Chinese remainder theorem'.
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[url=http://www.nature.com/nature/journal/v450/n7173/full/4501130a.html#top][color=#0000ff][/color][/url][list][*][b]Magnetic imaging: Getting to the point[/b][/list]
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[size=4][url=http://foxtrot.nature.com/nnano/journal/v2/n5/full/nnano.2007.105.html][color=#0000ff][i]Nature Nanotechnol.[/i] [b]2[/b], 301–306 (2007)[/color][/url][/size]j;x#qqk7M^
The resolution achieved by magnetic resonance imaging (MRI) has improved 60,000-fold, thanks to developments that couple MRI with atomic force microscopy.9tz(Ezk
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In magnetic atomic force microscopy, a sample, in the form of a thin film, is placed on an ultrasensitive cantilever that is suspended above a conical magnetic tip. The tip's strong magnetic field means that changes in the spin of atomic nuclei in the sample change the way the cantilever oscillates.
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John Mamin, at IBM's Almaden Research Center in San Jose, California, and his colleagues have developed highly magnetized tips with extremely sharp points, which generate large magnetic-field gradients. This allows them to achieve a resolution of 90 nanometres, making the system vastly more sensitive.YZ(R/xJ C!Wt/F'P
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[list][*][b]Planetary science: The whole of the Moon[/b][/list][img]http://www.nature.com/nature/journal/v450/n7173/images/4501130a-i2.0.jpg[/img]NASA
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[size=4][url=http://dx.doi.org/10.1016/j.epsl.2007.07.055][color=#0000ff]Earth Planet. Sci. Lett. 262, 438–449 (2007)[/color][/url][/size]4g\Cv3AF!X
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The consensus that Earth's satellite was created when a planet sometimes called Theia hit the early Earth has been tormented by a paradox for the past 30 years. Although computer simulations of the impact suggest that most of the Moon's mass came from Theia, its oxygen-isotope composition is very similar to that of Earth, suggesting that in fact it broke off from our home planet.5O
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Kaveh Pahlevan and David Stevenson of the California Institute of Technology in Pasadena believe that their model resolves this contradiction. They propose that the massive impact some 4.5 billion years ago vaporized most of both Earth and Theia. The disk of magma that eventually became the Moon remained linked to Earth by a wash of silicate vapour. Within this vapour, turbulent mixing evened out the isotopic differences between Earth and Theia before the Moon condensed out, the researchers suggest.
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[list][*][b]Quantum cryptography: Canary communication[/b][/list]t8T,@"o$N
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[url=http://dx.doi.org/10.1038/nphys629][color=#0000ff]Nature Phys. doi:10.1038/nphys629 (2007)[/color][/url][/size]2Y2tPRx
Physicists demonstrated the ability to distribute a quantum 'key' over a record 144 kilometres, the distance between two telescopes in the Canary Islands.
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Anton Zeilinger and Rupert Ursin of the University of Vienna in Austria and their colleagues used a laser to produce two photons 'entangled' in such a way that a measurement of one influences measurements of the other. Quantum cryptography makes use of this effect to distribute cryptographic keys no eavesdropper could intercept without being detected.^/Fu X8? e
While one photon was measured on the island of La Palma, the second was picked up by a telescope on the island of Tenerife. The team hopes that this advance will one day lead to satellite-based quantum communication.
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[url=http://www.nature.com/nature/journal/v450/n7173/full/4501130a.html#top][color=#0000ff][/color][/url][list][*][b]Particle physics: Hard-core calculations[/b][/list][size=4]?1F'y@-ynm_
[url=http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=PRLTAO000099000002022001000001&idtype=cvips&gifs=yes][color=#0000ff][i]Phys. Rev. Lett.[/i] [b]99[/b], 022001 (2007)[/color][/url][/size]CjTyn%L
Why do protons and neutrons stick close enough to form an atomic nucleus but never merge into a formless soup of their constituent quarks? In July, a group of Japanese physicists answered this question by publishing first-principles calculations of the particles' internal dynamics.
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The force between nuclear particles has long been known to be attractive at moderate distances but repulsive at very close quarters, yet quantitative explanations of this in terms of the behaviour of the particles' constituent quarks have proved elusive.5?8m@;l:V
Now Noriyoshi Ishii of the Universities of Tsukuba and Tokyo and his colleagues have used sophisticated algorithms and massively powerful computers to derive the familiar form of the nuclear force from the quantum field theory of quark interactions, called quantum chromodynamics. The achievement is both a computational [i]tour de force[/i] and a triumph for theory.
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[url=http://www.nature.com/nature/journal/v450/n7173/full/4501130a.html#top][color=#0000ff][/color][/url][list][*][b]Ecology: Hot threesome[/b][/list][url=http://www.nanost.net/bbs/forum-84-1.html][img]http://www.nature.com/nature/journal/v450/n7173/images/4501130a-i3.0.jpg[/img][/url]T. CRADDOCK/SPL