Circular photogalvanic effect induced by near-infrared radiation in InAs quantum wires patterned quasi two-dimensional electron system

In this work we investigated the InAs/InAlAs quantum wires (QWRs) superlattice by optically exciting the structure with near-infrared radiation. By varying the helicity of the radiation at room temperature we observed the circular photogalvanic effect related to the $C_{2v}$ symmetry of the structure, which could be attributed to the formation of a quasi two-dimensional system underlying in the vicinity of the QWRs pattern. The ratio of Rashba and Dresselhaus terms shows an evolution of the spin-orbit interaction in quasi two-dimensional structure with the QWR layer deposition thickness.Comment: 9 pages, 3 figure

Wetting layer evolution and its temperature dependence during self assembly of InAs/GaAs quantum dots

For InAs/GaAs(001) quantum dot (QD) system, the wetting layer (WL) evolution and its temperature dependence were studied using reflectance difference spectroscopy (RDS) and analyzed with a rate equation model. The WL thicknesses showed a monotonic increase at relatively low growth temperatures but a first increase and then decrease at higher temperatures, which were unexpected from the thermodynamic understanding. By adopting a rate equation model, the temperature dependence of QD growth was assigned as the origin of different WL evolutions. A brief discussion on the indium desorption was also given. Those results gave hints of the kinetic aspects of QD self-assembly.Comment: 13 pages, 3 figure

HIV/AIDS prevalence and behaviour in drug users and pregnant women in Kashgar Prefecture: Case report

Second Generation sub-population HIV Surveillance was undertaken in Kashgar City and Shache County, Xinjiang, Peoples Republic of China between December 2003 and January 2004, targeting injecting and mixed method drug users and pregnant and postnatal women. The study aimed to determine the extent to which the epidemic is shifting from a concentrated stage to a more generalised epidemic. One hundred and forty two (142) exclusively injecting drug users (66) and mixed method drug users (injecting and non-injecting-76) participated in this survey. Eight hundred and two (802) pregnant and postnatal women participated in the survey. In Kashgar City and Shache County the serum prevalence of HIV amongst injecting drug users was 56.06%, for mixed method drug users 48.68% and 0.38% in pregnant women. In Shache County HIV infection rates were significantly lower in drug user groups and amongst pregnant and post-natal women, at 2.22% and 0% respectively. The behavioral survey indicated that 15% of injecting drug users have shared needles (however sero prevalence and knowledge in relation to access to clean needles and syringes suggests that this may not reflect the actual situation). Knowledge of prevention of transmission strategies (not sharing needles and condom utilisation) is similar between both groups at 60–70%. However it appears that this knowledge has not significantly impacted on behavior such as needle sharing and condom utilisation. In Kashgar City and Shache County there have been very few interventions to support HIV/AIDS prevention, care and control. The results from this survey will inform future directions and the development and implementation of targeted interventions including targeted information dissemination and harm reduction strategies. This survey was funded by the Xinjiang HIV/AIDS Prevention and Care Project, a bilateral project jointly implemented by the Government of the People's Republic of China and the Government of Australia

Valence band offset of InN/BaTiO3 heterojunction measured by X-ray photoelectron spectroscopy

X-ray photoelectron spectroscopy has been used to measure the valence band offset of the InN/BaTiO(3 )heterojunction. It is found that a type-I band alignment forms at the interface. The valence band offset (VBO) and conduction band offset (CBO) are determined to be 2.25 ± 0.09 and 0.15 ± 0.09 eV, respectively. The experimental VBO data is well consistent with the value that comes from transitivity rule. The accurate determination of VBO and CBO is important for use of semiconductor/ferrroelectric heterojunction multifunctional devices

Serum proteomic, peptidomic and metabolomic profiles in myasthenia gravis patients during treatment with Qiangji Jianli Fang

BACKGROUND: Qiangji Jianli Fang (QJF) has been used for treatment of myasthenia gravis (MG) in China. However, our understanding of the effects of QJF against MG at the molecular level is limited. This study aims to investigate the effects of QJF treatment of MG patients on the protein, peptide and metabolite levels in serum. METHODS: High-throughput proteomic, peptidomic and metabolomic techniques were applied to investigate serum samples from 21 healthy individuals and 47 MG patients before and after QJF treatment via two-dimensional gel electrophoresis, matrix-assisted laser desorption/ionization time of flight mass spectrometry and liquid chromatography Fourier transform mass spectrometry, respectively. RESULTS: After QJF treatment, the expression levels of peptides m/z 1865.019, 2021.128 and 1211.668 of complement C3f increased (P = 0.004, P = 0.001 and P = 0.043, respectively), while that of peptide m/z 1739.931 of component C4b decreased (P = 0.043), in the serum of MG patients. The levels of γ-aminobutyric acid (P = 0.000) and coenzyme Q4 (P = 0.000) resumed their normal states. CONCLUSION: QJF could inhibit the activity of the complement system and restore the normal levels of metabolites

Effect of growth temperature on the morphology and phonon properties of InAs nanowires on Si substrates

Catalyst-free, vertical array of InAs nanowires (NWs) are grown on Si (111) substrate using MOCVD technique. The as-grown InAs NWs show a zinc-blende crystal structure along a < 111 > direction. It is found that both the density and length of InAs NWs decrease with increasing growth temperatures, while the diameter increases with increasing growth temperature, suggesting that the catalyst-free growth of InAs NWs is governed by the nucleation kinetics. The longitudinal optical and transverse optical (TO) mode of InAs NWs present a phonon frequency slightly lower than those of InAs bulk materials, which are speculated to be caused by the defects in the NWs. A surface optical mode is also observed for the InAs NWs, which shifts to lower wave-numbers when the diameter of NWs is decreased, in agreement with the theory prediction. The carrier concentration is extracted to be 2.25 × 1017 cm-3 from the Raman line shape analysis. A splitting of TO modes is also observed

Optical identification of electronic state levels of an asymmetric InAs/InGaAs/GaAs dot-in-well structure

We have studied the electronic state levels of an asymmetric InAs/InGaAs/GaAs dot-in-well structure, i.e., with an In0.15Ga0.85As quantum well (QW) as capping layer above InAs quantum dots (QDs), via temperature-dependent photoluminescence, photo-modulated reflectance, and rapid thermal annealing (RTA) treatments. It is shown that the carrier transfer via wetting layer (WL) is impeded according to the results of temperature dependent peak energy and line width variation of both the ground states (GS) and excited states (ES) of QDs. The quenching of integrated intensity is ascribed to the thermal escape of electron from the dots to the complex In0.15Ga0.85As QW + InAs WL structure. Additionally, as the RTA temperature increases, the peak of PL blue shifts and the full width at half maximum shrinks. Especially, the intensity ratio of GS to ES reaches the maximum when the energy difference approaches the energy of one or two LO phonon(s) of InAs bulk material, which could be explained by phonon-enhanced inter-sublevels carrier relaxation in such asymmetric dot-in-well structure