纳观尺度裂纹扩展微观机理的晶体相场法研究

采用晶体相场方法模拟不同预变形量的样品在单轴拉应变作用下的纳观裂纹扩展行为.观察纳观尺度的裂纹演化过程,结果表明：对于无预变形的样品,在拉应变作用下,由于裂口处应变集中,当应变量达到临界值时,裂口开始起裂并伴随位错出现,随着裂尖的前进位错伴随着裂尖而滑移.对于预变形的样品,在较小的临界应变值裂口起裂,且预变形量越大,裂纹越易起裂和扩展.在裂纹扩展早期阶段呈现出扩展-转向-扩展的长大特征,其本质是裂纹扩展由于裂尖附近的位错滑移受阻引起应变集中,造成主次原子晶面方向的原子键交替断裂,使得裂尖扩展沿[√3,1]和[√3,-1]方向交替改变而前进,裂纹边缘呈锯齿形状.样品的裂纹扩展后期出现显著的类似解理裂纹扩展行为,解理方向沿[√3,1]和[√3,-1]方向,且预变形量大的样品裂纹解理扩展更明显且扩展较快.     

生态防护在高速公路护坡中的应用研究

在系统总结国内外常用护坡方法的基础上,提出了要将工程护坡和植被护坡相结合的思想。文章介绍了一种新的特别适用于膨胀土边坡的生态防护方法———锚杆框架梁护坡,并对这种防护的护坡原理、力学机制、施工工艺等做了较为详细的阐述。     

循环荷载下土石混合体力学特性野外试验研究

土石混合体是一种物理、力学性质非常复杂的不连续介质。以云南某高速公路土石混合体边坡为例,分别对选取的3个试验点进行了单调加载、循环加载一次及多次循环加载试验,获取了其相应的剪切位移-剪切应力关系曲线,并对其曲线特征进行分析研究。通过对试样三维滑动面的形态分析,指出由于土石混合体三维滑动面的不规则性,利用传统的二维计算方法难以得到较为准确的强度参数。基于三维极限平衡理论,提出了土石混合体水平推剪试样强度参数的三维数据计算方法。并利用该方法得到了研究区土石混合体的相应的强度参数及残余强度参数。     

虎跳峡龙蟠右岸土石混合体粒度分形特征研究

应用分维理论对虎跳峡龙蟠右岸分布的土石混合体粒度分布的分维规律进行了研究分析,建立了平均粒径与相应的分维数之间的定量关系模型。通过研究表明,土石混合体具有良好的统计自相似性,由于其本身为级配不良土,在分维曲线上表现为双重分形分布,这种特殊的分维分布与土石混合体的成因及形成过程有关。     

An In-Situ Self-regeneration Catalyst for the Production of Renewable Penta-1,3-diene

Catalyst deactivation is a problem of great concern for many heterogeneous reactions. Here, an urchin-like LaPO₄ catalyst was easily developed for pentane-2,3-diol dehydration; it has an impressive ability to restore the activity in situ by itself during the reaction, accounting for its high stability. This facilitates the efficient production of renewable penta-1,3-diene from pentane-2,3-dione via a novel approach, where penta-2,3-diol was obtained as an intermediate in 95 % yield under mild conditions.     

Screening of antioxidant phenolic compounds in Chinese Rhubarb combining fast counter‐current chromatography fractionation and liquid chromatography/mass spectrometry analysis

In this paper, an effective method combing fast elution‐extrusion counter‐current chromatography (CCC) and LC/MS for rapid screening of antioxidative phenolic compounds in Chinese Rhubarb is presented. An integrated three‐coil CCC column (40 mL each coil) was used to accomplish the optimization of biphasic liquid system. In a single run (approximately 40 min), the solvent system composed of n‐hexane/ethyl acetate/methanol/water (1:1:1:1, v/v) was selected as optimum CCC liquid system for fast fractionation of the crude ethanol extract. With a 140 mL‐capacity CCC instrument, 100 mg Chinese Rhubarb extract was separated under the optimized conditions, producing six fractions in only 100 min. The quantities of each fraction were ～15 mg. In addition, each fraction was subjected to antioxidant activity assay and characterized by LC/MS analysis. Fifty compounds, including phenolic acids, phenolic glucosides and hydroxyanthraquinones, were detected by LC/MS/MS analysis. As a result, gallic acid together with Fr I showed excellent antioxidant activity, which was well consistent with previous studies and exhibited great potential for natural drug discovery program of the present method.     

Comparison of Cu(In,Ga)Se2 thin films deposited on different preferred oriented Mo back contact by RF sputtering from a quaternary target

The Cu(In, Ga)Se₂ (CIGS) thin films were deposited on bare glass and DC sputtered preferential oriented Mo-coated glass by RF sputtering from a single quaternary target. The structural and morphological properties of the films were characterized by X-ray diffraction (XRD), Raman spectroscope, energy dispersive X-ray spectrometer (EDS) and atomic force microscope (AFM). Preferred orientation of the Mo back contact was tuned between (110) and (211) plane by controlling the thickness. All the deposited CIGS thin films show (112) preferred oriented chalcopyrite structures. The films prepared on Mo-coated glass show higher quality crystallinity, better stoichiometry composition and more smooth surface morphology. Especially, the film on (211) oriented Mo-coated glass with the best integrated performance is expected to be a candidate absorber for high-efficiency CIGS solar cell device.     

Spectroscopic and laser-induced damage properties of Fe2+-doped fluorophosphate glass, a new color-separation material

Fe²⁺-doped fluorophosphate glass (FEFG), a new color-separation material, is prepared by a melt-quenching method. The spectroscopic and laser-induced damage (LID) properties of FEFG are investigated by transmittance spectroscopy, LID tests, scanning electron microscopy, and Raman spectroscopy. Results show that the sample has intensive absorption (>85 %) at 1,053 nm and high transmittance (~86.5 %) at 351 nm after introducing 0.3 wt% Fe₂O₃. The LID thresholds of 0.3 wt% Fe₂O₃-doped FEFG sample irradiated by 351- and 1,053-nm lasers with 8 ns pulse width are 4.5 and 36.0 J/cm², respectively. Thus, FEFG has laser-separation ability and can resist nanosecond laser irradiation, indicating that FEFG is a potential color-separation material for high-power lasers.     

电解质在混合溶剂中的活度系数及溶剂化数的研究——KClO4-CH3OH-非电解质体系

本文测定了KClO₄在甲醇-苯,甲醇-甲苯,甲醇-四氯化碳及甲醇-环己烷四个混合溶剂中的溶解度。使用A.D'Aprano[4]和C.W.Davies[2],报告的KClO₄及KNO₃在甲醇中的缔合常数,计算得“自由离子”浓度。盐的介质效应活度系数f_MX以S_o/S_m或S_o±、D_m±的表示值趋近相等,与非电解质的摩尔分数X₍Ne的关系符合经验公式:1gf_MX=kX_Ne,这里S_o和S_m分别是盐在甲醇和混合溶剂中的溶解度;脚注(±)标识“自由离子”;k为常数。电解质的溶剂化数公式:n₊+n_-=-21gf_MX/1gφ_ρ,对KClO₄在这些混合溶剂中的情况并不适用,这里n₊+n_-是正、负离子溶剂化数之和;φ_p是甲醇在混合溶剂中的体积分数。这个结果表明ClO₄^-的溶剂化层不是完全由甲醇分子所形成,非电解质也影响着ClO₄^-在这些溶剂中的溶剂化层。KNO₃的实验数据,溶解度公式和溶剂化数公式是引自李芝芬、黄子卿、刘瑞麟以前的论文。     

DECOMPOSITION OF BMO FUNCTIONS AND FACTORIZATION OF $\[{A_p}\]$ WEIGHTS IN MARTINGALE SETTING

Let $\[(\Omega ,F,\mu )\]$ be a probabilty space with an increasing family $\[{\{ {F_t}\} _{t > 0}}\]$ of sub-fields satisfying the usual conditions. The following results are obtained: for $\[f \in BMO\]$, we have $\[f = g - h\]$ with $\[g,h \in BLO\]$; if in addition, f satisfies then for $\[s > 0\]$ arbitrary, g,h can be chosen such that $\[g,h \in BLO\]$, and $$\[E({\varepsilon ^{(a - \varepsilon )(g - {g_t})}}|{F_t}) \le {C_{a,\beta ,\varepsilon }},E({\varepsilon ^{(\beta - \varepsilon )(h - {h_t})}}|{F_t}) \le {C_{a,\beta ,\varepsilon }}\]$$ and for weights z, we have $\[z \in {A_p} \cap S \Leftrightarrow z = {z_1}z_2^{1 - p}\]$ with $\[{z_i} \in {A_i} \cap S,i = 1,2\]$, where $\[S = \{ \begin{array}{*{20}{c}} {weight}&{z:C{z_{{T^ - }}} \le {z_T} \le C{z_{{T^ - }}}} \end{array}\} \]$, $\[\forall \]$ stopping times T, outside a null set }.