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881.
D.C. Johnston 《Solid State Communications》1977,24(10):699-702
The occurrence of superconductivity at temperatures up to 9.6 K is reported for the system M(Rh0.85Ru0.15)4B4, where M can be Y or a rare earth element. In contrast, most members of the isostructural series MRu4B4 are either not superconducting or order magnetically instead. These materials were found to crystallize in a body-centered-tetragonal structure, with space group I41/acd and 8 formula units per unit cell. The atomic positions were determined through a structural study of the LuRu4B4 compound. These results are discussed with reference to the previously reported primitive tetragonal MRh4B4 system of superconducting or ferromagnetic compounds. 相似文献
882.
Zegers RG van Den Berg AM Brandenburg S Fleurot FR Fujiwara M Guillot J Hannen VM Harakeh MN Laurent H van Der Schaaf K van Der Werf SY Willis A Wilschut HW 《Physical review letters》2000,84(17):3779-3782
The (nat)Pb(3He,tp) reaction at E(3He) = 177 MeV was studied to identify 2Planck's over 2piomega isovector monopole strength in Bi isotopes. Monopole strength was found in the region -45
相似文献
883.
An analogy is stressed between the order-parameter symmetries of the two-dimensional d-pairing wave superconductors and of liquid-crystal mesophases formed from achiral bent-shaped molecules. It leads to a definition of a class of liquid-crystal states which are the analogs of the unconventional superconducting states, and are characterized by a loss of discrete symmetry operations of the parent state. 相似文献
884.
Background
Neurons require an elaborate system of intracellular transport to distribute cargo throughout axonal and dendritic projections. Active anterograde and retrograde transport of mitochondria serves in local energy distribution, but at the same time also requires input of ATP. Here we studied whether brain-type creatine kinase (CK-B), a key enzyme for high-energy phosphoryl transfer between ATP and CrP in brain, has an intermediary role in the reciprocal coordination between mitochondrial motility and energy distribution. Therefore, we analysed the impact of brain-type creatine kinase (CK-B) deficiency on transport activity and velocity of mitochondria in primary murine neurons and made a comparison to the fate of amyloid precursor protein (APP) cargo in these cells, using live cell imaging. 相似文献885.
Kinney WA Zhang X Williams JI Johnston S Michalak RS Deshpande M Dostal L Rosazza JP 《Organic letters》2000,2(19):2921-2922
A short formal synthesis of squalamine is described, utilizing the biotransformation product 2, which is available in one step from commercially available 3-keto-23,24-bisnorchol-4-en-22-ol (1). Regioselective C-22 oxidation and C-24 sulfation of the corresponding alcohols in the presence of a free C-7 alcohol make for an efficient preparation of squalamine intermediate 11. 相似文献
886.
van Der Lee AM van Druten NJ van Exter MP Woerdman JP Poizat JP Grangier P 《Physical review letters》2000,85(22):4711-4714
We investigate the impact of the Petermann-excess-noise factor K>/=1 on the possibility of intensity noise squeezing of laser light below the standard quantum limit. Using an N-mode model, we show that squeezing is limited to a floor level of 2(K-1) times the shot noise limit. Thus, even a modest Petermann factor significantly impedes squeezing, which becomes impossible when K>/=1.5. This appears as a serious limitation for obtaining sub-shot-noise light from practical semiconductor lasers. We present experimental evidence for our theory. 相似文献
887.
Y. Manzhur W.-D. Zeitz M. J. Prandolini W. D. Brewer P. Imielski J. Schubert K. Johnston 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,59(3):277-283
Using refined preparation techniques, cadmium guest atoms have been
positioned at different sites on the surfaces of nickel crystals. The
magnetic hyperfine fields and the electric field gradients at the Cd nuclei
were measured by time-dependent perturbed angular correlation (TDPAC)
spectroscopy of the emitted gamma radiations. By measuring the combined
interactions, electric field gradients and magnetic hyperfine fields can be
unambiguously attributed to each surface site. The signs of the magnetic
hyperfine fields are determined by applying an external magnetic field and
choosing the appropriate γ-ray detector configuration. The measured
fields correlate with the number of neighbouring host atoms. Band structure
calculations confirm this finding and predict magnetic fields for various
sp elements from the band structure of the s-like conduction electrons. The
quadrupolar interactions are manifestations of the balance in the occupation
of the guest p-sublevels. These results provide new information on the
structure and formation of electronic configurations of sp elements in different local environments and will contribute to understanding electronic effects on surfaces. 相似文献
888.
Armstrong DS Arvieux J Asaturyan R Averett T Bailey SL Batigne G Beck DH Beise EJ Benesch J Bimbot L Birchall J Biselli A Bosted P Boukobza E Breuer H Carlini R Carr R Chant N Chao YC Chattopadhyay S Clark R Covrig S Cowley A Dale D Davis C Falk W Finn JM Forest T Franklin G Furget C Gaskell D Grames J Griffioen KA Grimm K Guillon B Guler H Hannelius L Hasty R Allen AH Horn T Johnston K Jones M Kammel P Kazimi R King PM Kolarkar A Korkmaz E Korsch W Kox S Kuhn J Lachniet J Lee L Lenoble J 《Physical review letters》2007,99(9):092301
889.
Upadhya PC Fan W Burnett A Cunningham J Davies AG Linfield EH Lloyd-Hughes J Castro-Camus E Johnston MB Beere H 《Optics letters》2007,32(16):2297-2299
The generation of terahertz (THz) transients in photoconductive emitters has been studied by varying the spatial extent and density of the optically excited photocarriers in asymmetrically excited, biased low-temperature-grown GaAs antenna structures. We find a pronounced dependence of the THz pulse intensity and broadband (>6.0 THz) spectral distribution on the pump excitation density and simulate this with a three-dimensional carrier dynamics model. We attribute the observed variation in THz emission to changes in the strength of the screening field. 相似文献
890.