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41.
Wong J Krisch M Farber DL Occelli F Schwartz AJ Chiang TC Wall M Boro C Xu R 《Science (New York, N.Y.)》2003,301(5636):1078-1080
We report an experimental determination of the phonon dispersion curves in a face-centered cubic (fcc) delta-plutonium-0.6 weight % gallium alloy. Several unusual features, including a large elastic anisotropy, a small-shear elastic modulus C', a Kohn-like anomaly in the T1[011] branch, and a pronounced softening of the [111] transverse modes, are found. These features can be related to the phase transitions of plutonium and to strong coupling between the lattice structure and the 5f valence instabilities. Our results also provide a critical test for theoretical treatments of highly correlated 5f electron systems as exemplified by recent dynamical mean field theory calculations for delta-plutonium. 相似文献
42.
Hafezparast M Klocke R Ruhrberg C Marquardt A Ahmad-Annuar A Bowen S Lalli G Witherden AS Hummerich H Nicholson S Morgan PJ Oozageer R Priestley JV Averill S King VR Ball S Peters J Toda T Yamamoto A Hiraoka Y Augustin M Korthaus D Wattler S Wabnitz P Dickneite C Lampel S Boehme F Peraus G Popp A Rudelius M Schlegel J Fuchs H Hrabe de Angelis M Schiavo G Shima DT Russ AP Stumm G Martin JE Fisher EM 《Science (New York, N.Y.)》2003,300(5620):808-812
Degenerative disorders of motor neurons include a range of progressive fatal diseases such as amyotrophic lateral sclerosis (ALS), spinal-bulbar muscular atrophy (SBMA), and spinal muscular atrophy (SMA). Although the causative genetic alterations are known for some cases, the molecular basis of many SMA and SBMA-like syndromes and most ALS cases is unknown. Here we show that missense point mutations in the cytoplasmic dynein heavy chain result in progressive motor neuron degeneration in heterozygous mice, and in homozygotes this is accompanied by the formation of Lewy-like inclusion bodies, thus resembling key features of human pathology. These mutations exclusively perturb neuron-specific functions of dynein. 相似文献
43.
Hong D Gupta R Ancliff P Atzberger A Brown J Soneji S Green J Colman S Piacibello W Buckle V Tsuzuki S Greaves M Enver T 《Science (New York, N.Y.)》2008,319(5861):336-339
Understanding cancer pathogenesis requires knowledge of not only the specific contributory genetic mutations but also the cellular framework in which they arise and function. Here we explore the clonal evolution of a form of childhood precursor-B cell acute lymphoblastic leukemia that is characterized by a chromosomal translocation generating a TEL-AML1 fusion gene. We identify a cell compartment in leukemic children that can propagate leukemia when transplanted in mice. By studying a monochorionic twin pair, one preleukemic and one with frank leukemia, we establish the lineal relationship between these "cancer-propagating" cells and the preleukemic cell in which the TEL-AML1 fusion first arises or has functional impact. Analysis of TEL-AML1-transduced cord blood cells suggests that TEL-AML1 functions as a first-hit mutation by endowing this preleukemic cell with altered self-renewal and survival properties. 相似文献
44.
当前我国企业专利管理存在许多问题,面对参与国际市场竞争的严峻形势,必须要加强企业专利管理工作,并提出了一些专利管理的方法。 相似文献
45.
Theoretical and experimental studies indicate that, with a high-resolution scanning electron microscope, it is now possible to obtain pictures of a single heavy atom resting on a thin carbon substrate. 相似文献
46.
Myxococcus xanthus cells can glide forward by retracting type IV pili. Tgl, an outer membrane lipoprotein, is necessary to assemble pili. Tgl mutants can be transiently "stimulated" if brought into end-to-end contact with tgl+ donor cells. By separating the stimulated recipient cells from donor cells, we found that Tgl protein was transferred from the donors to the rescued recipient cells. Mutants lacking CglB lipoprotein, which is part of a second gliding engine, could also be stimulated, and CglB protein was transferred from donor to recipient cells. The high transfer efficiency of Tgl and CglB proteins suggests that donor and recipient cells briefly fuse their outer membranes. 相似文献
47.
Aluminum is considered to approach an "ideal" metal or free electron gas. The valence electrons move freely, as if unaffected by the presence of the metal ions. Therefore, the electron redistribution due to chemical bonding is subtle and has proven extremely difficult to determine. Experimental measurements and ab initio calculations have yielded substantially different results. We applied quantitative convergent-beam electron diffraction to aluminum to provide an experimental determination of the bonding electron distribution. Calculation of the electron distribution based on density functional theory is shown to be in close agreement. Our results yield an accurate quantitative correlation between the anisotropic elastic properties of aluminum and the bonding electron and electrostatic potential distributions. 相似文献
48.
Ryo Kubota Mark A. Schell Gabriel D. Peckham Joanne Rue Anne M. Alvarez Caitilyn Allen Daniel M. Jenkins 《Journal of General Plant Pathology》2011,77(3):182-193
New rapid diagnostic methods are urgently needed to discriminate the quarantine pathogen Ralstonia solanacearum (Rs) race 3 biovar 2 (R3B2) from other populations of Rs that lack the adaptation to cause bacterial wilt disease in temperate
regions. We used an in silico bioinformatic approach to identify several genome sequences potentially specific to R3B2 strains. Primer sets were designed
to PCR-amplify sequences in these regions, and four sets were ultimately shown to be >99% accurate for detection of R3B2 strains.
On the basis of these results, several primers were designed to enable development of a loop-mediated isothermal amplification
assay that was rapid, technologically simple, and essentially 100% accurate for identification of R3B2 when applied to a comprehensive
collection of geographically diverse Rs strains. We fortuitously found that a sequence in one of the “R3B2-specific” regions
has ~90% identity to a sequence present in strains of the blood disease bacterium (BDB), a member of the Rs species complex
that infects banana. Alignments of these sequences allowed design of a second PCR primer set that proved 100% accurate for
identification of BDB strains when tested on the 22 BDB strains available to us. These results demonstrate the power of in silico genomic subtraction for rapid identification of population-specific DNA sequences and for the development of simple, reliable
detection methods for Rs subpopulations. 相似文献
49.
Gu L Kelm MA Hammerstone JF Beecher G Holden J Haytowitz D Prior RL 《Journal of agricultural and food chemistry》2003,51(25):7513-7521
A normal-phase HPLC-MS/MS method was applied to screen for proanthocyanidins in 88 different kinds of foods. Thirty-nine foods were found to contain proanthocyanidins. These foods include 19 kinds of fruits, eight cereals/beans, seven nuts, two beverages, two spices, and one vegetable. Twenty-five kinds of foods were found to contain both oligomeric (DP = 10) and polymeric proanthocyanidins (DP > 10), and the other 14 foods contained only oligomers. Procyanidins with B-type linkages were detected as the only components in 21 foods and also as principal components in the others. Propelargonidins were identified in pinto bean, raspberry, strawberry, and almond, etc. Plum, avocado, peanut, curry, and cinnamon were identified as potential sources of A-type proanthocyanidins in addition to cranberry. Thiolytic degradation and MS/MS analyses indicated that the A-type linkages are present as a terminal unit in plum or between the extension units in curry, cinnamon, and avocado, whereas A-type linkages exist at both positions in cranberry and peanut. 相似文献
50.
John D. Peles Travis C. Glenn Heather A. Brant Angela K. Wall Charles H. Jagoe 《Water, air, and soil pollution》2006,173(1-4):151-162
Mercury concentrations in largemouth bass (Micropterus salmoides) bass were compared among five reservoirs in South Carolina. Three of these reservoirs (Lake Russell, Lake Thurmond, and Lake Marion) are accessible to the public and two (L-Lake and Par Pond) are located on the U.S. Department of Energy's Savannah River Site (SRS), which is closed to public access. Age-adjusted mercury concentrations were significantly higher in SRS bass compared to the offsite reservoirs. In addition, mercury concentrations were significantly higher in bass from Par Pond compared to L-Lake and in bass from Lakes Russell and Thurmond compared to Lake Marion. No mercury concentrations in excess of the U.S. Food and Drug Administration action level (1.0 mg?kg?1) were found in any bass from the public-accessible reservoirs. However, the majority of fish from these reservoirs had mercury concentrations that fall into or exceed the U.S. Environmental Protection Agency consumption category of “no more than one per week". In addition, most fish from these reservoirs had mercury levels in excess of those believed to be detrimental to sensitive avian species. 相似文献