2,568 research outputs found
In situ revelation of a zinc-blende InN wetting layer during Stranski-Krastanov growth on GaN(0001) by molecular-beam epitaxy
Indium nitride (InN) exists in two different structural phases, the equilibrium wurtzite (w) and the metastable zinc-blende (zb) phases. It is of scientific interest and practical relevance to examine the crystal structure of the epifilms during growth. In this paper, we use Patterson function inversion of low-energy electron diffraction I-V curves to reveal the preferential formation of zinc-blende InN wetting layer during the Stranski-Krastanov growth on GaN(0001). For three-dimensional islands nucleated afterwards on top of the wetting layer and for thick InN films, the equilibrium wurtzite structure is observed instead. This in situ revelation of the InN lattice structure is confirmed by ex situ transmission electron microscopy studies. Finally, the formation of zb-InN layer on w-GaN is explained in terms of the strain in the system. © 2005 The American Physical Society.published_or_final_versio
基于小波变换的单历元算法及其在结构振动监测中的应用研究
Author name used in this publication: 丁晓利Author name used in this publication: 黄丁发, HUANG Ding-faAuthor name used in this publication: 陈惠珊Title in Traditional Chinese: 基于小波變換的單歷元算法及其在結構振動監測中的應用研究Journal title in Traditional Chinese: 測繪學報2005-2006 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe
Molecular lens of the nonresonant dipole force
A cylindrical molecular lens is formed by focusing a nanosecond IR laser pulse. Trajectories of a CS2 molecular beam deflected by the lens are traced using the velocity map imaging technique. The characteristic lens parameters including the focal length, minimum beam width, and distance to the minimum-width position are determined. The laser intensity dependence of the parameters is in good agreement with theoretical predictions. Exciting possibilities for molecular optics and a new type of optical chromatography are opened up.open394
Shotgun proteomics: Tools for analysis of marine particulate proteins
National Natural Science Foundation of China [40821063, 40376032, 40476053]; Ministry of Science and Technology [2008DF100440]; Program for New Century Excellent Talents in Xiamen UniversityThis study sought a high resolution and high-throughput method to identify and characterize proteins from marine particulate organic matter (POM) using proteomic approaches. The results showed that only a limited number of discrete protein spots were distinguished using two-dimensional electrophoresis (2-DE). Most protein spots were faint and small in 2-DE gels, with a heavy unresolved smeared staining background, indicating 2-DE was not a good high resolution method to separate particulate proteins for identification and characterization. The shotgun proteomic approach combining one-dimensional electrophoresis and capillary liquid chromatography-tandem mass spectrometry as well as the NCBI protein database search was successfully applied to identify and characterize particulate proteins. Using this approach, 737 proteins matching one or more peptides were detected in a POM sample collected from the 41 m water layer in the basin area of the western South China Sea. Of these, 184 were identified as high-confidence proteins matching two or more peptides, including photosynthetic proteins, transporters, molecular chaperones, and porins. In addition to these proteins with known functions, a significant number of novel proteins (accounting for similar to 30% of the proteins identified) were also detected. The identification of a large number of high-confidence proteins in the POM sample demonstrated that the shotgun proteomic approach is reliable and feasible for the study of particulate proteins and will provide a powerful tool to comprehensively investigate the nature and dynamics of POM in the ocean
Dynamic Fracture Instability Of Tough Bulk Metallic Glass
We report the observations of a clear fractographic evolution from vein pattern, dimple structure, and then to periodic corrugation structure, followed by microbranching pattern, along the crack propagation direction in the dynamic fracture of a tough Zr41.2Ti13.8Cu12.5Ni10Be22.5 (Vit.1) bulk metallic glass (BMGs) under high-velocity plate impact. A model based on fracture surface energy dissipation and void growth is proposed to characterize this fracture pattern transition. We find that once the dynamic crack propagation velocity reaches a critical fraction of Rayleigh wave speed, the crack instability occurs; hence, crack microbranching goes ahead. Furthermore, the correlation between the critical velocity of amorphous materials and their intrinsic strength such as Young's modulus is uncovered. The results may shed new insight into dynamic fracture instability for BMGs. (C) 2008 American Institute of Physics
Resonances in and
A partial wave analysis is presented of and
from a sample of 58M events in the BES II detector. The
is observed clearly in both sets of data, and parameters of the
Flatt\' e formula are determined accurately: (stat)
(syst) MeV/c, MeV/c, . The data also exhibit a strong peak
centred at MeV/c. It may be fitted with and a
dominant signal made from interfering with a smaller
component. There is evidence that the signal is
resonant, from interference with . There is also a state in with MeV/c and
MeV/c; spin 0 is preferred over spin 2. This state, , is
distinct from . The data contain a strong peak due to
. A shoulder on its upper side may be fitted by interference
between and .Comment: 17 pages, 6 figures, 1 table. Submitted to Phys. Lett.
Measurement of the Branching Fraction of J/psi --> pi+ pi- pi0
Using 58 million J/psi and 14 million psi' decays obtained by the BESII
experiment, the branching fraction of J/psi --> pi+ pi- pi0 is determined. The
result is (2.10+/-0.12)X10^{-2}, which is significantly higher than previous
measurements.Comment: 9 pages, 8 figures, RevTex
Search for K_S K_L in psi'' decays
K_S K_L from psi'' decays is searched for using the psi'' data collected by
BESII at BEPC, the upper limit of the branching fraction is determined to be
B(psi''--> K_S K_L) < 2.1\times 10^{-4} at 90% C. L. The measurement is
compared with the prediction of the S- and D-wave mixing model of the
charmonia, based on the measurements of the branching fractions of J/psi-->K_S
K_L and psi'-->K_S K_L.Comment: 5 pages, 1 figur
First observation of psi(2S)-->K_S K_L
The decay psi(2S)-->K_S K_L is observed for the first time using psi(2S) data
collected with the Beijing Spectrometer (BESII) at the Beijing Electron
Positron Collider (BEPC); the branching ratio is determined to be
B(psi(2S)-->K_S K_L) = (5.24\pm 0.47 \pm 0.48)\times 10^{-5}. Compared with
J/psi-->K_S K_L, the psi(2S) branching ratio is enhanced relative to the
prediction of the perturbative QCD ``12%'' rule. The result, together with the
branching ratios of psi(2S) decays to other pseudoscalar meson pairs
(\pi^+\pi^- and K^+K^-), is used to investigate the relative phase between the
three-gluon and the one-photon annihilation amplitudes of psi(2S) decays.Comment: 5 pages, 4 figures, 2 tables, submitted to Phys. Rev. Let
First Measurements of eta_c Decaying into K^+K^-2(pi^+pi^-) and 3(pi^+pi^-)
The decays of eta_c to K^+K^-2(pi^+pi^-) and 3(pi^+pi^-) are observed for the
first time using a sample of 5.8X10^7 J/\psi events collected by the BESII
detector. The product branching fractions are determined to be B(J/\psi-->gamma
eta_c)*B(eta_c-->K^+K^-pi^+pi^-pi^+pi^-)=(1.21+-0.32+-
0.23)X10^{-4}, and (J/\psi-->gamma eta_c)*
B(eta_c-->pi^+pi^-pi^+pi^-pi^+pi^-)= (2.59+-0.32+-0.48)X10^{-4}. The upper
limit for eta_c-->phi pi^+pi^-pi^+pi^- is also obtained as B(J/\psi-->gamma
eta_c)*B(eta_c--> phi pi^+pi^-pi^+pi^-)< 6.03 X10^{-5} at the 90% confidence
level.Comment: 11 pages, 4 figure
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