Shape effects on the yield stress and deformation of silicon nanowires: A molecular dynamics simulation

The tension and compression of single-crystalline silicon nanowires (SiNWs) with different cross-sectional shapes are studied systematically using molecular dynamics simulation. The shape effects on the yield stresses are characterized. For the same surface to volume ratio, the circular cross-sectional SiNWs are stronger than the square cross-sectional ones under tensile loading, but reverse happens in compressive loading. With the atoms colored by least-squares atomic local shear strain, the deformation processes reveal that the failure modes of incipient yielding are dependent on the loading directions. The SiNWs under tensile loading slip in {111} surfaces, while the compressive loading leads the SiNWs to slip in the {110} surfaces. The present results are expected to contribute to the design of the silicon devices in nanosystems

Atomistic Simulation On Size-Dependent Yield Strength And Defects Evolution Of Metal Nanowires

A simple derivation based on continuum mechanics is given, which shows the surface stress is critical for yield strength at ultra-small scales. Molecular dynamics (MD) simulations with modified embedded atom method (MEAM) are employed to investigate the mechanical behaviors of single-crystalline metal nanowires under tensile loading. The calculated yield strengths increasing with the decrease of the cross-sectional area of the nanowires are in accordance with the theoretical prediction. Reorientation induced by stacking faults is observed at the nanowire edge. In addition. the mechanism of yielding is discussed in details based on the snapshots of defects evolution. The nanowires in different crystallographic orientations behave differently in stretching deformation. This study on the plastic properties of metal nanowires will be helpful to further understanding of the mechanical properties of nanomaterials. (C) 2009 Elsevier B.V. All rights reserved

青藏高原东北部MODIS地表温度重建及其与气温对比分析

通过遥感获取地表温度(地温,LST)可以弥补气象站LST数据局地性的不足。但受某些因素影响,遥感LST影像存在噪音像元,影响了LST数据的应用。本文提出了一种基于高程-温度回归关系的空间重建算法,对2008年青藏高原MODIS LST影像异常低值像元进行了重建,得到空间完整的LST时间序列。分别将原始LST和重建LST与研究区62个气象站最高气温进行对比分析,结果表明,重建前后LST与最高气温一致性很好,相关系数分别为0.88和0.91,各气象站平均相关系数达到0.898,LST一般高于气温,平均偏差为6.98℃。地气温差与海拔、土地覆盖、季节和噪音水平有关。海拔越高,地气温差越大;植被覆盖越好,地气温差越小;温度越高,温差越大。研究还发现,重建后的数据在森林覆盖区仍然残留噪音,这需要结合LST的质量控制信息做进一步研究

Ni-Nb-Ti三元系富Ni侧fcc相的互扩散及原子迁移率研究（英文）

利用EPMA技术测定了Ni-Nb-Ti三元系富Ni侧合金在1273K下的扩散数据,并使用Whittle和Green方法计算了Ni-Nb-Ti三元系在1273 K下的互扩散系数。通过DICTRA软件优化得到Ni-Nb-Ti三元系的fcc相的原子迁移率,运用优化得到的的原子迁移率计算出的互扩散系数与实验数据具有较好的一致性,从而验证了所得的原子迁移率的可靠性。同时通过运用原子迁移率拟合各扩散偶的的浓度-距离曲线和扩散路径,进一步验证了原子迁移率的合理性。National Key Basic Research and Development Program of China(2016YFB0701401,2017YFB0702901);;\nNational Natural Science Foundation of China(51571168,51771158,51471138);;\nInternational Science and Technology Cooperation Program of China(2014DFA53040

二元调幅分解型合金扩散偶中自组装片层组织的生长现象（英文）

采用耦合弹性场的相场法对调幅分解型合金扩散偶中的片层组织生长现象进行研究,通过考虑浓度起伏和弹性各向异性模拟二元调幅分解型合金扩散偶中的组织演化。模拟结果表明:即使在较大的弹性各向异性条件下,周期性层片组织的层数随着初始浓度起伏的增大而减小。片层组织生长的主要原因可归结于初始界面化学势的不连续所引起的定向扩散。Project(2017YFB0702401) supported by the National Key R&D Program of China;;Project(51301146) supported by the National Natural Science Foundation of China;;Projects(20720170038,20720170048) supported by the Fundamental Research Funds for the Central Universities,Chin

绿洲农业高效用水技术集成与示范

简要技术说明： 该成果围绕棉花、葡萄、小麦3大作物,从干旱绿洲区作物高效用水和提高作物水分生产效率的目标出发,研究形成了棉花高效用水技术模式3套、葡萄高效用水技术模式1套、小麦优化灌溉节水及配套栽培技术模式1套、干旱绿洲区农业高效用水管理技术模式1套,开发了15项农业节水关键技术和1套“农业灌溉决策支持系统”,筛选出节水配套抗旱小麦品种2个、抗旱棉花品种1个,制定了农业高效用水技术规程7项,研发了专利产品1项、软件著作权登记1项,人才培养12名、发表论文45篇。通过对高效灌溉技术、农艺高效用水技术、高效用水管理技术等3方面的关键技术的集成与创新,研究形成了干旱绿洲区特色作物(棉花、葡萄、..

Aripiprazole versus other atypical antipsychotics for schizophrenia

BACKGROUND: In most western industrialised countries, second generation (atypical) antipsychotics are recommended as first line drug treatments for people with schizophrenia. In this review we specifically examine how the efficacy and tolerability of one such agent - aripiprazole - differs from that of other comparable second generation antipsychotics. OBJECTIVES: To evaluate the effects of aripiprazole compared with other atypical antipsychotics for people with schizophrenia and schizophrenia-like psychoses. SEARCH METHODS: We searched the Cochrane Schizophrenia Group Trials Register (November 2011), inspected references of all identified studies for further trials, and contacted relevant pharmaceutical companies, drug approval agencies and authors of trials for additional information. SELECTION CRITERIA: We included all randomised clinical trials (RCTs) comparing aripiprazole (oral) with oral and parenteral forms of amisulpride, clozapine, olanzapine, quetiapine, risperidone, sertindole, ziprasidone or zotepine for people with schizophrenia or schizophrenia-like psychoses. DATA COLLECTION AND ANALYSIS: We extracted data independently. For dichotomous data we calculated risk ratios (RR) and their 95% confidence intervals (CI) on an intention-to-treat basis based on a random-effects model. Where possible, we calculated illustrative comparative risks for primary outcomes. For continuous data, we calculated mean differences (MD), again based on a random-effects model. We assessed risk of bias for each included study. MAIN RESULTS: We included 12 trials involving 6389 patients. Aripiprazole was compared to olanzapine, risperidone and ziprasidone. All trials were sponsored by an interested drug manufacturer. The overall number of participants leaving studies early was 30% to 40%, limiting validity (no differences between groups).When compared with olanzapine no differences were apparent for global state (no clinically important change: n = 703, 1 RCT, RR short-term 1.00 95% CI 0.81 to 1.22; n = 317, 1 RCT, RR medium-term 1.08 95% CI 0.95 to 1.22) but mental state tended to favour olanzapine (n = 1360, 3 RCTs, MD total Positive and Negative Syndrome Scale (PANSS) 4.68 95% CI 2.21 to 7.16). There was no significant difference in extrapyramidal symptoms (n = 529, 2 RCTs, RR 0.99 95% CI 0.62 to 1.59) but fewer in the aripiprazole group had increased cholesterol levels (n = 223, 1 RCT, RR 0.32 95% CI 0.19 to 0.54) or weight gain of 7% or more of total body weight (n = 1095, 3 RCTs, RR 0.39 95% CI 0.28 to 0.54).When compared with risperidone, aripiprazole showed no advantage in terms of global state (n = 384, 2 RCTs, RR no important improvement 1.14 95% CI 0.81 to 1.60) or mental state (n = 372, 2 RCTs, MD total PANSS 1.50 95% CI -2.96 to 5.96).One study compared aripiprazole with ziprasidone (n = 247) and both the groups reported similar change in the global state (n = 247, 1 RCT, MD average change in Clinical Global Impression-Severity (CGI-S) score -0.03 95% CI -0.28 to 0.22) and mental state (n = 247, 1 RCT, MD change PANSS -3.00 95% CI -7.29 to 1.29).When compared with any one of several new generation antipsychotic drugs the aripiprazole group showed improvement in global state in energy (n = 523, 1 RCT, RR 0.69 95% CI 0.56 to 0.84), mood (n = 523, 1 RCT, RR 0.77 95% CI 0.65 to 0.92), negative symptoms (n = 523, 1 RCT, RR 0.82 95% CI 0.68 to 0.99), somnolence (n = 523, 1 RCT, RR 0.80 95% CI 0.69 to 0.93) and weight gain (n = 523, 1 RCT, RR 0.84 95% CI 0.76 to 0.94). Significantly more people given aripiprazole reported symptoms of nausea (n = 2881, 3 RCTs, RR 3.13 95% CI 2.12 to 4.61) but weight gain (7% or more of total body weight) was less common in people allocated aripiprazole (n = 330, 1 RCT, RR 0.35 95% CI 0.19 to 0.64). Aripiprazole may have value in aggression but data are limited. This will be the focus of another review. AUTHORS' CONCLUSIONS: Information on all comparisons are of limited quality, are incomplete and problematic to apply clinically. Aripiprazole is an antipsychotic drug with a variant but not absent adverse effect profile. Long-term data are sparse and there is considerable scope for another update of this review as new data emerges from the many Chinese studies as well as from ongoing larger, independent pragmatic trials

JUNO Sensitivity on Proton Decay p→νˉK+p\to \bar\nu K^+ Searches

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this paper, the potential on searching for proton decay in $p\to \bar\nu K^+$ mode with JUNO is investigated.The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits to suppress the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar\nu K^+$ is 36.9% with a background level of 0.2 events after 10 years of data taking. The estimated sensitivity based on 200 kton-years exposure is $9.6 \times 10^{33}$ years, competitive with the current best limits on the proton lifetime in this channel