Native deep level defects in ZnO single crystal grown by CVT method - art. no. 68410I

Hall effect, photoluminescence (PL), infrared absorption, deep level transient spectroscopy (DLTS), and Raman scattering have been used to study property and defects of ZnO single crystal grown by a chemical vapor transport method (CVT). As-grown ZnO is N type with free electron density Of 10(16)-10(17)cm(-3). It has a slight increase after 900 degrees C annealing in oxygen ambient. The DLTS measurement revealed four deep level defects with energy at 0.30eV, 0.50eV, 0.68eV and 0.90eV in the as-grown ZnO sample, respectively. After the high temperature annealing, only the 0.5eV defect survive and has a concentration increase. PL results of the as-grown and annealed ZnO indicate that the well-known green emission disappear after the annealing. The result suggests a correlation between the 0.68eV defect and the green PL peak. Results of P-doped ZnO were also compared with the undoped ZnO sample. The nature of the defects and their influence on the material property have been discussed.

Native oxided AlAs current blocking layer for AIGaInP high brightness light emitting diodes

Native Oxide AlAs layer were employed to block the current injection from the tup anode. The luminous intensity exceeded 75 mcd of the LED chip with native oxide AlAs layer sandwiched 5 mu m AlGaAs current spreading layer under 20 mA current injection. Electrical and optical properties the LED chip and plastically sealed lamp were measured. Aging of the LED chip and lamp were performed under 70 degrees C and room temperature, Experiment results shown that there is no apparent effect of the native oxided AlAs layer and the process on the reliability of the LED devices.

关于黄土丘陵典型地区植被建设中有关问题的研究Ⅲ、乡土树种在造林中的意义

根据调查资料 ,论述了外来种和乡土树种在土壤水分 ,林下自然条件下更新等方面的有利和不利因素 ,探讨了经济效益 ,乡土树种的不可替代作用等问题 ,最后提出了“延安试验研究区造林应以乡土树种为主体 ,辅以外来树种”的思路 ,针对这一思路提出了对策

N2O fluxes from the native and grazed semi-arid steppes and their driving factors in Inner Mongolia, China

This paper presents results of 2 years (from January 2005 to December 2006) of measurement of N2O fluxes from the native and grazed Leymus chinensis (LC) steppes in Inner Mongolia, China using the static opaque chamber method. The measurement was at a frequency of twice per month in the growing season and once per month in the non-growing season. In addition, the possible effect of water-heat factors on N2O fluxes was statistically analyzed. The results indicated that there were distinct seasonal patterns in N2O fluxes with large fluxes in spring, summer, and autumn but negative fluxes in winter. The annual net emission of N2O ranging from 0.24 to 0.30 kg N2O-N ha(-1) and from 0.06 to 0.26 kg N2O-N ha(-1) from the native and grazed LC steppe, respectively. Grazing activities suppressed N2O production. In the growing season, soil moisture was the primary driving factor of N2O fluxes. The high seasonal variation of N2O fluxes was regulated by the distribution of effective rainfall, rather than precipitation intensity. Air temperature or soil temperature at 0, 5, and 10 cm depth was the most restricting factor of N2O fluxes in the non-growing season.

Localization of Na+-K+ ATPases in Quasi-Native Cell Membranes

Na+-K+ ATPases have been observed and located by in situ AFM and single molecule recognition technique, topography and recognition imaging (TREC) that is a unique technique to specifically identify single protein in complex during AFM imaging. Na+-K+ ATPases were well distributed in the inner leaflet of cell membranes with about 10% aggregations in total recognized proteins. The height of Na+-K+ ATPases measured by AFM is in the range of 12-14 nm, which is very consistent with the cryoelectron microscopy result. The unbinding force between Na+-K+ ATPases in the membrane and anti-ATPases on the AFM tip is about 80 pN with the apparent loading rate at 40 nN/s.

Native growth of vertically pattened ZnO nanowire arrays under mild conditions without templates or catalysts

Based on the implications of a pellet experiment,we have designed and implemented a low temperature(≤90℃) approach to generate native patterned,vertically aligned ZnO nanoarrys without any templates or catalysts.This simple,economic and spontaneous patterning process offers a promising avenue for overcoming several inherent limitations of the artificial manners[1].While the purity,orientation and electrical properties of the as prepared materials allow them to be applied in various fields.

In-situ FTIR study on adsorption and oxidation of native and thermally denatured calf thymus DNA at glassy carbon electrodes

In-situ Fourier transform infra-red (FTIR) spectra of native and thermally denatured calf thymus DNA (CT DNA) adsorbed and/or oxidized at a glassy carbon (GC) electrode surface are reported. The adsorption of native DNA occurs throughout the potential range (-0.2 similar to 1.3 V) studied, and the adsorbing state of DNA at electrode surface is changed from through the C=O band of bases and pyrimidine rings to through the C=O of cytosine and imidazole rings while the potential shifts negatively from 1.3 V to -0.2 V. An in-situ FTIR spectrum of native CT DNA adsorbed at GC electrode surface is similar to that of the dissolved DNA, indicating that the structure of CT DNA is not distorted while it is adsorbed at the GC electrode surface. In the potential range of -0.2 similar to 1.30 V, the temperature-denatured CT DNA is adsorbed at the electrode surface first, then undergoes electrochemical oxidation reaction and following that, diffuses away from the electrode surface. (C) 2001 Elsevier Science B.V. All rights reserved.

A selenium-containing abzyme, the activity of which surpassed the level of native glutathione peroxidase

Using two different glutathione derivatives as hapten, we have prepared two abzymes, which display glutathione peroxidase (GPX) activity. Their GPX activities are 0.2 and 1.6 times that of natural GPX from rabbit liver, respectively. Selenium content analysis indicates that the activity difference between the two abzymes is possibly attributed to the conformation difference of the abzymes.

General expression for probabilistic estimation of multiphase structure invariants in the case of a native protein and multiple derivatives. Application to estimates of the three-phase structure invariants

Concise probabilistic formulae with definite crystallographic implications are obtained from the distribution for eight three-phase structure invariants (3PSIs) in the case of a native protein and a heavy-atom derivative [Hauptman (1982). Acta Cryst. A38, 289-294] and from the distribution for 27 3PSIs in the case of a native and two derivatives [Fortier, Weeks & Hauptman (1984). Acta Cryst. A40, 646-651]. The main results of the probabilistic formulae for the four-phase structure invariants are presented and compared with those for the 3PSIs. The analysis directly leads to a general formula of probabilistic estimation for the n-phase structure invariants in the case of a native and m derivatives. The factors affecting the estimated accuracy of the 3PSIs are examined using the diffraction data from a moderate-sized protein. A method to estimate a set of the large-modulus invariants, each corresponding to one of the eight 3PSIs, that has the largest \Delta\ values and relatively large structure-factor moduli between the native and derivative is suggested, which remarkably improves the accuracy, and thus a phasing procedure making full use of all eight 3PSIs is proposed.

DIRECT OBSERVATION OF NATIVE AND UNFOLDED GLUCOSE-OXIDASE STRUCTURES BY SCANNING-TUNNELING-MICROSCOPY

Native and unfolded glucose oxidase (GOD) structures have been directly observed with scanning tunnelling microscopy (STM) for the first time. STM images show an opening butterfly-shaped pattern for the native GOD. When GOD molecules are extended on anodi

Consensus scoring for enriching near-native structures from protein-protein docking decoys

The identification of near native protein-protein complexes among a set of decoys remains highly challenging. A stategy for improving the success rate of near native detection is to enrich near native docking decoys in a small number of top ranked decoys. Recently, we found that a combination of three scoring functions (energy, conservation, and interface propensity) can predict the location of binding interface regions with reasonable accuracy. Here, these three scoring functions are modified and combined into a consensus scoring function called ENDES for enriching near native docking decoys. We found that all individual scores result in enrichment for the majority of 28 targets in ZDOCK2.3 decoy set and the 22 targets in Benchmark 2.0. Among the three scores, the interface propensity score yields the highest enrichment in both sets of protein complexes. When these scores are combined into the ENDES consensus score, a significant increase in enrichment of near-native structures is found. For example, when 2000 dock decoys are reduced to 200 decoys by ENDES, the fraction of near-native structures in docking decoys increases by a factor of about six in average. ENDES was implemented into a computer program that is available for download at http://sparks.informatics.iupui.edu.

Refining near-native protein-protein docking decoys by local resampling and energy minimization

How to refine a near-native structure to make it closer to its native conformation is an unsolved problem in protein-structure and protein-protein complex-structure prediction. In this article, we first test several scoring functions for selecting locally resampled near-native protein-protein docking conformations and then propose a computationally efficient protocol for structure refinement via local resampling and energy minimization. The proposed method employs a statistical energy function based on a Distance-scaled Ideal-gas REference state (DFIRE) as an initial filter and an empirical energy function EMPIRE (EMpirical Protein-InteRaction Energy) for optimization and re-ranking. Significant improvement of final top-1 ranked structures over initial near-native structures is observed in the ZDOCK 2.3 decoy set for Benchmark 1.0 (74% whose global rmsd reduced by 0.5 angstrom or more and only 7% increased by 0.5 angstrom or more). Less significant improvement is observed for Benchmark 2.0 (38% versus 33%). Possible reasons are discussed.