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991.
N. G. C. Astrath F. B. G. Astrath J. Shen J. Zhou C. E. Gu L. C. Malacarne P. R. B. Pedreira A. C. Bento M. L. Baesso 《Applied physics. B, Lasers and optics》2009,94(3):473-481
A complete theoretical model is presented for the thermal mirror technique under top-hat laser excitation. Considering the
attenuation of the top-hat excitation laser intensity along the thickness of a sample due to its optical absorption coefficient,
we calculate the laser-induced temperature and surface deformation profiles. A simplified theoretical model for a high absorption
sample is also developed. The center intensity of a probe beam reflected from the thermal mirror at a detector plane is derived.
Numerical simulation shows that the thermal mirror under the top-hat laser excitation is as sensitive as that under Gaussian
laser excitation. With top-hat laser excitation, the experimental results of thermo-physical properties of opaque samples
are found to be well consistent with literature values, validating the theory. 相似文献
992.
Gu W Huang H Meng K Yang P Fu D Luo H Wang Y Yao B Zhan Z 《Applied biochemistry and biotechnology》2009,157(2):113-123
A novel phytase gene, appA, was isolated by degenerate polymerase chain reaction (PCR) and thermal asymmetric interlaced PCR from Dickeya paradisiaca. The full-length appA comprises 1278 bp and encodes 425 amino acid residues, including a 23-residue putative N-terminal signal peptide. The deduced
amino acid sequence of appA reveals the conserved motifs RHGXRXP and HD, which are typical of histidine acid phosphatases; significantly, APPA shows
maximum identity (49%) to a phytase from Klebsiella pneumoniae. To characterize the properties of APPA, appA was expressed in Escherichia coli and purified. The purified recombinant APPA has two pH optima at pH 4.5 and 5.5, optimum temperature at 55 °C, specific activity
of 769 U/mg, and good pH stability. The K
m value for the substrate sodium phytate is 0.399 mM with a V
max of 666 U/mg. To our knowledge, this is the first report of a phytase or phytase gene isolated from Dickeya.
Weina Gu and Huoqing Huang contributed equally to this work. 相似文献
993.
Zhang F Gu X Kaiser RI Balucani N Huang CH Kao CH Chang AH 《The journal of physical chemistry. A》2008,112(17):3837-3845
The reaction of atomic boron, B(2P), with the simplest alkene, C2H4, has been investigated under single collision conditions in crossed beam experiments with mass spectrometric detection. Our experimental data clearly showed that the atomic boron versus hydrogen exchange reaction led to molecule(s) of gross formula C2H3B via bound intermediate(s). According to the experimentally derived fraction of the available energy released as product translational energy, we propose that an important reaction pathways is the one leading to the borirene plus atomic hydrogen and/or the one leading to ethynylborane plus atomic hydrogen. The experimental results are accompanied by electronic structure calculations of the relevant potential energy surface and RRKM estimates of the product branching ratio. According to RRKM calculations, within the limit of complete energy randomization, the three isomers borirene, BH=C=CH2 and BH2-CCH, are all formed, with BH2-CCH being the dominant one. The discrepancies between the trend of the product translational energy distributions and the picture emerging from RRKM estimates are a symptom that a statistical treatment is not warranted for this system. 相似文献
994.
Despite that carbon is tetravalent identical to silicon, first-principles calculations reveal that stable step structures on diamond (001) are entirely different from those on silicon. Moreover, pristine Si(001) is flat; pristine diamond (001) could be rough due to negative step formation energies. A generic bond-counting rule is established, which should apply to most carbon structures where sp2 and sp3 hybrids coexist: e.g., it provides a qualitative account of the step energy order without detailed calculation. Our findings agree with experimental observations. 相似文献
995.
The intrinsic transport properties of zigzag graphene nanoribbons (ZGNRs) are investigated using first-principles calculations. It is found that although all ZGNRs have similar metallic band structure, they show distinctly different transport behaviors under bias voltages, depending on whether they are mirror symmetric with respect to the midplane between two edges. Asymmetric ZGNRs behave as conventional conductors with linear current-voltage dependence, while symmetric ZGNRs exhibit unexpected very small currents with the presence of a conductance gap around the Fermi level. This difference is revealed to arise from different coupling between the conducting subbands around the Fermi level, which is dependent on the symmetry of the systems. 相似文献
996.
Block M Bachelet C Bollen G Facina M Folden CM Guénaut C Kwiatkowski AA Morrissey DJ Pang GK Prinke A Ringle R Savory J Schury P Schwarz S 《Physical review letters》2008,100(13):132501
A new long-lived isomeric state in (65)Fe has been discovered with Penning trap mass spectrometry and high-precision mass measurements of the neutron-rich isotopes (63-65)Fe and (64-66)Co have been performed with the Low-Energy Beam and Ion Trap Facility at the NSCL. For the new isomer in (65)Fe an excitation energy of 402(5) keV has been determined from the measured mass difference between the isomeric and ground states. The mass uncertainties of all isotopes have been reduced by a factor of 10-100 compared to previous results. In the case of (64)Co the previous mass value was found to deviate by about 5 standard deviations from the new measurement. 相似文献
997.
Zhang W Liu G Zhao L Liu H Meng J Dong X Lu W Wen JS Xu ZJ Gu GD Sasagawa T Wang G Zhu Y Zhang H Zhou Y Wang X Zhao Z Chen C Xu Z Zhou XJ 《Physical review letters》2008,100(10):107002
Laser-based angle-resolved photoemission measurements with superhigh resolution have been carried out on an optimally doped Bi(2)Sr(2)CaCu(2)O(8) high temperature superconductor. New high energy features at approximately 115 meV and approximately 150 meV, in addition to the prominent approximately 70 meV one, are found to develop in the nodal electron self-energy in the superconducting state. These high energy features, which cannot be attributed to electron coupling with single phonon or magnetic resonance mode, point to the existence of a new form of electron coupling in high temperature superconductors. 相似文献
998.
Druart G Taboury J Guérineau N Haïdar R Sauer H Kattnig A Primot J 《Optics letters》2008,33(4):366-368
Diffractive axicons are optical components producing achromatic nondiffracting beams. They thus produce a focal line rather than a focal point for classical lenses. This gives the interesting property of a long focal depth. We show that this property can be used to design a simple imaging system with a linear variable zoom by using and translating a diffractive axicon as the only optical component. 相似文献
999.
Observation of multiple higher-order stopgaps from three-dimensional chalcogenide glass photonic crystals 总被引:1,自引:0,他引:1
Nicoletti E Zhou G Jia B Ventura MJ Bulla D Luther-Davies B Gu M 《Optics letters》2008,33(20):2311-2313
For the first time to our knowledge the observation of near-IR multiple higher-order stopgaps in three-dimensional photonic crystals (PhCs) fabricated using the direct-laser-writing method in thick chalcogenide glass films is reported. The fabrication and etching conditions necessary to realize well-defined structures are presented. The fabricated PhCs exhibit higher-order stopgaps, which are only evident in high-quality structures. The higher-order stopgaps observed permit these high-refractive-index and high-nonlinear PhCs to be used directly as functional photonic devices operating at telecommunication wavelengths without further miniaturizing structural dimensions. 相似文献
1000.
In this paper, we present a theoretical investigation on the Faraday effect in paramagnetic neodymium gallium garnet (Nd3Ga5O12) by taking account of the SO and CF interactions, the superexchange interaction and the external magnetic field. It is demonstrated that under high magnetic field, the Faraday rotation (θ) is strongly nonlinear with the external magnetic field (He) while the coefficients of deeply dependent on the frequency of the incident light and temperature, and the Verdet constant V(θ/He) is also a function of He. Furthermore, theoretical calculations show that the reciprocity of the Faraday effect cannot be neglected under high magnetic field. The theoretical results are in good agreement with the experimental data. 相似文献