Competition between Radiative Power and Dissipation Power in the Refrigeration Process in Oxide Multifilms

The maximum refrigeration power dependence on the doping density in the p-BaTiO3/BaTiO3/SrTiO3/BaTiO3/ n-BaTiO3 system and in the p-AlGaAs/AlGaAs/GaAs/AlGaAs/n-AlGaAs system is obtained respectively based on the opto-thermionic refrigeration model. The results show that the maximum refrigeration power in the p-BaTiO3/BaTiO3/SrTiO3/BaTiO3/n-BaTiO3 system increases dramatically with the increase of doping density from 1.0×1018 cm-3 to 5.0×1019 cm-3 while that in the p-AlGaAs/AlGaAs/GaAs/AlGaAs/n-AlGaAs system is nearly a constant. It is found that the different Auger coefficients and the competition between radiative power and dissipation power lead to the different behavior of the maximum refrigeration power dependence on the doping density of the two systems.     

微电流作用下铁片置换海绵铋粉

针对铁粉置换沉积海绵铋所得铋粉品位较低的缺点,本工艺采用铁片置换海绵铋,铁片为阳极,石墨为阴极,直流微电流作用,电流密度5×10-3 A/cm2,温度40℃,所得海绵状铋粉品位在90％以上.通过置换过程的宏观动力学研究表明,其置换过程符合一级反应速率规律,活化能Ea=13.72 kJ/mol,反应速率方程为v=3.2470 ×c(Bi3+)exp(-13720/RT),置换过程的控制步骤为扩散控制.电化学分析结果显示,微电流作用很好的促进了置换过程,且置换海绵状铋粉品位高,杂质少,尤其铅含量明显降低.     

A new shunt DC active filter of power supply in a steady high magnetic field facility

A DC active power filter is an indispensable part in a high power and high stability power supply system, especially in the power supply system of the Steady High Magnetic Field Facility, which requires that the current ripple should be limited to 50 parts per million. In view of the disadvantages of the series DC active power filter and shunt Pulse Width Modulation DC active filter, this paper puts forward a novel DC active filter by combining the advantages of the transistor regulator and the shunt type. The structure and principle of the new shunt linear active filter are introduced. Meanwhile, the design of several key components that construct the new shunt linear active filter is also analyzed. The simulation model and an experimental prototype of the shunt linear active filter are developed, and the results verify that the parameter design is reasonable and the shunt active filter has a good filter effect.     

煤沥青水浆的制备及影响规律的研究

以中温煤沥青为原料,经冷冻粉碎后制得具有一定粒径级配的煤沥青粉,加入适量分散剂和水在高速搅拌下制备煤沥青水浆.结果表明,JL-C01中裂乳化剂是制备煤沥青水浆的优良分散剂,在此基础上进一步考察了分散剂用量及浆体浓度对煤沥青成浆性、煤沥青水浆流变性及稳定性的影响.结果表明,最大成浆浓度为70％;在分散剂用量相同的条件下,...     

橙红色荧光粉Ca3Y2(Si3O9)2∶Sms3+的制备及发光性能的表征

采用高温固相法合成了Ca3Y2－2x(Si3O9)2∶2xSm3+系列荧光粉,并表征了材料的发光特性.X射线衍射图谱表明:得到的样品为纯相Ca3Y2(Si3O9)2晶体;样品的激发光谱主要来源于Sm3+的特征激发;分别采用紫外、近紫外和蓝光作为激发源,样品均发射橙红光.在402 nm近紫外光激发下,Ca3Y2(Si3O9)2∶Sm3+发射光谱主要由3个峰组成,发射峰值分别位于565 nm、604 nm和651 nm,归属于Sm3+的4G5/2→6HJ/2(J=5, 7, 9)跃迁,其中发射主峰位于604 nm处.通过时间分辨光谱测得Sm3+的4G5/2能级的荧光寿命.随着Sm3+摩尔浓度的增加,样品发光强度先增强后减弱,当x=0.02时发光强度达到最大,浓度猝灭机理为电偶极-电偶极相互作用.     

钙钛矿氧化物异质结的研究进展

在过去几年中,为了研究钙钛矿氧化物异质结的物性和潜在的应用前景,我们进行了许多探索。在本文中,我们总结了对钙钛矿氧化物异质结一些物理性质的理论描述,揭示了La0.9Sr0.1MnO3/SrNb0.01Ti0.99O3异质结中发现的正磁电阻效应和横向光电效应的物理起源。我们提出的理论模型将有助于理解界面对钙钛矿氧化物异质结各种性质的影响。     

多元t分布的一致渐进正态性

讨论了多元t分布一致渐进正态性的条件,利用不等式法估计了二者之间的Kullback-Leibler距离,给出了Kullback-Leibler距离表达式,最后对多元t分布一致渐进正态性进行了模拟验证.     

Photon-interactions with perovskite oxides

Photons with variable energy, high coherency, and switchable polarization provide an ideal tool-kits for exploring the cutting-edge scientific questions in the condensed matter physics and material sciences. Over decades, extensive researches in the sample fabrication and excitation have employed the photon as one of the important means to synthesize and explore the low-dimensional quantum materials. In this review, we firstly summarize the recent progresses of the state-of-the-art thin-film deposition methods using excimer pulsed laser, by which syntactic oxides with atomic-unit-cell-thick layers and extremely high crystalline quality can be programmatically fabricated. We demonstrate that the artificially engineered oxide quantum heterostructures exhibit the unexpected physical properties which are absent in their parent forms. Secondly, we highlight the recent work on probing the symmetry breaking at the surface/interface/interior and weak couplings among nanoscale ferroelectric domains using optical second harmonic generation. We clarify the current challenges in the in-situ characterizations under the external fields and large-scale imaging using optical second harmonic generation. The improvements in the sample quality and the non-contact detection technique further promote the understanding of the mechanism of the novel properties emerged at the interface and inspire the potential applications, such as the ferroelectric resistive memory and ultrahigh energy storage capacitors.     

新型吩噻嗪-咔咯锰（III）配合物的合成及其催化氧化DNA断裂的活性

以单羟基自由咔咯为起始原料,与吩噻嗪-10-碳酰氯（PTZ）反应制得吩噻嗪 咔咯二元化合物(2）; 2与醋酸锰反应合成了一种新型5,15-二（2,3,4,5,6)-五氟苯基-10-(4-吩噻嗪苯基)咔咯锰（Ⅲ）配合物(3),收率80.0%,其结构经UV-Vis和HR-MS（ESI）表征。通过琼脂糖凝胶电泳实验探讨了其催化氧化DNA的活性。结果表明：在过氧化氢存在下,3能有效引起超螺旋pBR322 DNA发生氧化断裂,3浓度为250 μmol·L^-1时,氧化断裂DNA的活性达34%。通过紫外滴定、荧光滴定、圆二色谱推断3与小牛胸腺(ct-DNA）的结合模式为外部结合。     

新型吩噻嗪-咔咯锰(Ⅲ)配合物的合成及其催化氧化DNA断裂的活性

以单羟基自由咔咯为起始原料,与吩噻嗪-10-碳酰氯(PTZ)反应制得吩噻嗪-咔咯二元化合物(2);2与醋酸锰反应合成了一种新型5,15-二(2,3,4,5,6)-五氟苯基-10-(4-吩噻嗪苯基)咔咯锰(Ⅲ)配合物(3),收率80.0%,其结构经UV-Vis和HR-MS(ESI)表征。通过琼脂糖凝胶电泳实验探讨了其催化氧化DNA的活性。结果表明:在过氧化氢存在下,3能有效引起超螺旋p BR322 DNA发生氧化断裂,3浓度为250μmol·L~(-1)时,氧化断裂DNA的活性达34%。通过紫外滴定、荧光滴定、圆二色谱推断3与小牛胸腺(ct-DNA)的结合模式为外部结合。