不同氧化锆相的稳定性及电子结构的第一性原理研究

通过密度泛函理论计算了不同氧化锆相的晶体结构参数,在所有晶相模型结构优化的基础上,分析了在一般温度和压力下不同晶相稳定程度不同的原因。使用3种不同的泛函计算了不同晶相的电子能带结构和态密度电荷差分密度,发现在氧化锆高温稳定相体系中,由于强关联电子的相互作用增强,传统密度泛函理论的广义梯度近似平面波超软赝势泛函及其修正的Hubbard U方法都会严重低估能带带隙,因此所得各层能带位置不准确,而使用B3LYP杂化泛函计算的结果则可以很好地与已有实验结果相吻合。结合杂化泛函计算出的态密度和差分密度数据,在理论上从电子间相互作用的角度解释了氧化锆不同晶相的稳定性、导电性及光吸收性能。     

CO2环境介质下16Mn钢的高温高压腐蚀性能

利用高温高压釜,通过失重法、SEM、XRD以及电子探针微观结构分析等方法,对16Mn钢在3种不同高温条件下以及1 MPa分压的饱和CO2环境介质中的腐蚀性能进行研究.结果表明,在60、90、120℃下,16Mn钢发生严重的CO2腐蚀,表现出高的腐蚀速率,且伴有不同程度的点蚀、条状腐蚀特征.随着温度的升高,腐蚀速率呈下降再上升的趋势,90℃时最小,各温度下表面都生成了Fe3C为主的腐蚀产物膜。研究发现,Cl-为点蚀的"激发剂",并且在点蚀坑内富集,导致局部Cl-浓度差不同,形成电偶腐蚀,促进点蚀发生;腐蚀过程显示CO2腐蚀的局部腐蚀特征是各种因素相互作用的结果.     

益肾除痹汤治疗坐骨神经痛56例疗效观察

目的观察自拟益肾除痹汤治疗坐骨神经痛临床疗效.方法采用自拟益肾除痹汤治疗坐骨神经痛患者56例,随证加减.结果治愈33例,好转19例,无效4例,治愈率58.9%,总有效率92.9%.结论自拟益肾除痹汤治疗坐骨神经痛疗效好,值得研究应用.     

复杂条件下薄煤层综采方案研究

葛亭煤矿1160采区地面有密集建筑物,其煤层含有一层硫化铁硬夹矸,底板距奥灰较近。针对这些实际情况,通过理论分析和计算确定1160采区条带法开采工作面采出宽度：基岩厚度30 m以下区域,条带采出宽度30m,基岩厚度30 m以上区域条带采出宽度为40 m。工作面选用MG200/456-QWD型采煤机但是对其做了相应的改造：滚筒为强力滚筒,滚筒直径为1 100 mm,截齿采用国外凯南麦特加强型镐型截齿。通过对底板承压水突水情况的分析,认为煤层开采的安全性较高,正常情况下无突水危险。     

Insight into influence of thermodynamic coefficients on transient negative capacitance in Zr-doped HfO2 ferroelectric capacitors

We study the influence of the thermodynamic coefficients on transient negative capacitance for the Zr-doped HfO₂ (HZO) ferroelectric capacitors by the theoretical simulation based on the Landau-Khalatnikov (L-K) theory and experimental measurement of electrical properties in the resistor-ferroelectric capacitor (R-FEC) circuit. Our results show that the thermodynamic coefficients α, β and γ also play a key role for the transient NC effect besides the viscosity coefficient and series resistor. Moreover, the smaller coefficients α and β, the more significant the transient NC effect. In addition, we also find that the thermodynamic process of transient NC does not obey the generally accepted viewpoint of Gibbs free energy minimization.     

SP825树脂分离纯化益母草总黄酮和总生物碱的研究

本文旨在寻找一种能够同时有效分离纯化益母草总黄酮和总生物碱有效部位的方法.即,采用SP825大孔吸附树脂富集益母草总黄酮,收集水洗脱液,分离纯化得到总生物碱;60%乙醇洗脱得到总黄酮,分别采用比色法于可见分光光度计测定样品总黄酮和总生物碱含量.结果发现:总黄酮含量为21.35%,收率为64.17%;总生物碱含量为25.65%,收率为65.98%.从而证实:SP825大孔吸附树脂能够有效富集益母草总黄酮,同时,从水洗脱液分离纯化得到的总生物碱有效部位含量和收率均较高.该方法经济节省,操作简便,并且提高了药材的使用率.     

铜氧化物高温超导体的元素掺杂效应

简要介绍高温超导体的发展以及研究状况.实验显示,可用正电子湮没参数来表征元素掺杂对超导体的超导转变温度、结构缺陷和相变的影响.表明了正电子湮没技术是研究铜氧化物高温超导体的元素掺杂效应的有效手段.     

Dark Energy Density in Brane World

We present a possible explanation to the tiny positive cosmological constant under the frame of AdS5 spacetime embedded by a dS4 brahe. We calculate the dark energy density by summing the zero point energy of massive scalar fields in AdS5 spacetime. Under the assumption that the radius of AdS5 spacetime is of the same magnitude as the radius of observable universe, the dark energy density in dS4 brahe is obtained, which is smaller than the observational value. The reasons are also discussed.     

溶剂对TS-1催化丙烯环氧化反应的影响

溶剂对钛硅分子筛TS-1催化丙烯环氧化反应具有重要影响,该文对甲醇、异丙醇和仲丁醇3种醇溶剂及丙酮、乙腈和四氢呋喃等有机溶剂中环氧化反应活性进行了研究,实验结果活性顺序为:甲醇>异丙醇>仲丁醇>乙腈>丙酮>四氢呋喃。以催化反应机理为基础,通过电子效应、空间位阻效应、溶剂极性、物理扩散和分配、溶剂氧化副反应、环氧丙烷(PO)醚化副反应、催化剂失活和丙烯溶解度等多种因素分析了溶剂对环氧化反应的影响。电子效应、空间位阻效应和溶剂极性是影响反应的重要因素,研究工作为今后同类反应溶剂的选取提供理论根据和指导,为PO清洁生产工艺的进一步工业化奠定基础。     

Stable single longitudinal mode erbium-doped silica fiber laser based on an asymmetric linear three-cavity structure

We present a stable linear-cavity single longitudinal mode (SLM) erbium-doped silica fiber laser. It consists of four fiber Bragg gratings (FBGs) directly written in a section of photosensitive erbium-doped fiber (EDF) to form an asymmetric three-cavity structure. The stable SLM operation at a wavelength of 1545.112 nm with a 3-dB bandwidth of 0.012 nm and an optical signal-to-noise ratio (OSNR) of about 60 dB is verified experimentally. Under laboratory conditions, the performance of a power fluctuation of less than 0.05 dB observed from the power meter for 6 h and a wavelength variation of less than 0.01 nm obtained from the optical spectrum analyzer (OSA) for about 1.5 h are demonstrated. The gain fiber length is no longer limited to only several centimeters for SLM operation because of the excellent mode-selecting ability of the asymmetric three-cavity structure. The proposed scheme provides a simple and cost-effective approach to realizing a stable SLM fiber laser.