Bianchi type I expanding universe in Weyl-invariant gravity with a quartic interaction term

We will focus on the effect of a Weyl-invariant model with a quadratic interaction term and a free scalar field \(\psi \). A set of analytic solutions will be obtained for this model. This model provides a dynamical alternative to the standard \(\Lambda \)CDM model. In particular, we will show that the quartic Weyl-invariant model prediction is consistent with the Hubble diagram observations.     

The Decomposition Reaction of 4‐Acetylsydnones Arylhydrazones

The acidic decomposition of 4‐acetylsydnones arylhydrazones 2 results in the formation of 4‐arylhydrazo‐1,2‐pyrazolin‐5‐ones 3 and 4‐arylamino‐1,2,3‐triazoles 4 , respectively. The reactions of 4‐acetylsydnones 1 with arylhydrazines 5 afford compounds 3 as the only products in the absence of solvent.     

热循环加载条件下空洞对EBGA焊点可靠性的影响

空洞是球栅阵列(BGA：Ball Grid Array)器件在装配过程中形成的主要缺陷之一,本文以增强性BGA(EBGA：Enhanced BGA)为研究对象,采用统一型粘塑性Anand本构方程描述Sn63Pb37的粘塑性力学行为,应用非线性有限元的方法分析了不同位置和大小的空洞对焊点疲劳寿命的影响,为制定装配后的BGA焊点接收标准提供理论参考。     

1,4-二(2-苯基-1,3,4-噁二唑基-5)苯及其衍生物的研究(Ⅱ)

本文讨论了18种溶剂对1,4-二(2-苯基-1,3,4-(口恶)二唑基-5)苯及2-苯基的对位有叔丁基取代的衍生物的紫外、荧光光谱以及荧光量子产率的影响。     

AW模式对梅雨暴雨的预报试验

利用引进的中尺度10层湿模式——AW模式,对长江流域梅雨期大暴雨进行了模拟试验,检验了模式的预报能力,比较了不同精度初始场对梅雨预报的影响,探讨了梅雨暴雨形成和发展的某些机理。主要结果如下: 1.AW模式可报出梅雨暴雨过程,对暴雨的落区、强度、天气尺度环境场和中尺度动力、热力条件都具有相当的预报能力; 2.对流层低层的切变线和沿切变线活动的中尺度扰动是梅雨暴雨的主要影响系统。雨带位于900百帕切变线附近,暴雨中心位于900百帕切变线上的中尺度扰动中心附近。900百帕中尺度涡度的加强,与暴雨中心的形成相对应; 3.梅雨暴雨的发展与高空天气尺度和低空中尺度涡度中心的耦合关系密切,当低层中尺度涡度中心移近高层天气尺度负涡度中心之下时,降水增强; 4.在雨区上空的边界层附近,存在一个湿暖盖,产生了对流性降水叠加在稳定降水之上的独特的梅雨暴雨结构; 5.对流加热对雨区的环境流场和温湿场影响很大,对流加热通过Ekman-CISK、热成风调整过程以及激发重力惯性波不稳定等方式来加强暴雨系统。     

Research on the Synthesis and Optical Properties of Isomeric Bichromophoric Compounds --3-or 4- Phenyl 7-Coumarin ω-9-Anthracene-Poly-methene Carboxylate

Six bichromophoric compounds-substituted coumarin ω -9-anthra-cene-poly-methene carboxylate and five model compounds were synthesized. Among them, eight compounds are new ones. Intramolecular singlet energy transfer has been demonstrated in the bichromophoric compounds 1? and studied in some detail. The absorption spectra of the compounds 1-6 bear evidence that the π-electron systems of coumarin and anthracene ring do not overlap appreciably. The coumarin moiety of the bichromophoric compounds molecule was excited at 314nm and the resulting fluorescence was characteristic of the anthracene group. The efficiency of transfer of singlet excitation from coumarin moiety to the anthracene grou is about 100% in both calculation and observation and the rate of the singlet energy transfer is about 1014 sec in the compounds 4-6. A possible mechanism of intramolecular energy transfer was suggested. The difference between 4-phenyl compounds 1-3 and 3-phenyl compounds 4-6 in spectra was com -pared.     

2,6-二取代苯并二噁唑的研究(Ⅲ)——2,6-二苯乙烯基苯并二噁唑和它们的衍生物

通过2,6-二甲基苯并[1,2d;4,5d′]二噁唑和2,6-二甲基苯并[1,2d;5,4d′]二噁唑分别与苯甲醛和取代苯甲醛缩合备制取七种相应的2,6-二苯乙烯基苯并[1,2d;4,5d′]二噁唑和2,6-二苯乙烯基苯并(1,2d;5,4d′]二噁唑。测定了全部化合物的熔点、红外光谱、紫外光谱、荧光光谱、激光转换效率。     

交流示波极谱滴定的研究(ⅩⅢ)——有机碱及有机酸盐类药物在水溶液中的中和滴定

本文用交流示波极谱中和滴定技术,在水溶液中直接滴定有机碱和有机酸的盐类药物,简便、快速、准确。     

The effects of electrode materials on the switching behaviour of the amorphous semiconductors Si12Ge10As30Te48

The switching behaviour of the amorphous chalcogenide alloy Si₁₂Ge₁₀As₃₀Te₄₈ has been systematically investigated using silver, indium, aluminum, and graphite for electrodes. The experimental results show that the stability in both the threshold voltage for the onset of switching action, and the holding current required to maintain the conducting state, depends strongly on electrode materials. The switching mechanisms related to the electrical and thermal properties of various electrode materials are discussed, and experimental evidence of the deteriorating effect of some electrode materials is given.     

Liquid-Crystalline Properties of Unsaturated Piperazine-2,5-dione Derivatives

The synthesis, characterization, and mesomorphic properties of a new type of liquid-crystalline compounds, (3Z,6Z)-3,6-bis(3,4-dialkoxybenzylidene)piperazine-2,5-diones are reported. These compounds were derived from unsaturated piperazine-2,5-dione as the core group, and were prepared by condensation reactions of 1,4-diacetylpiperazine-2,5-dione and 3,4-dialkoxybenzaldehydes. The products were characterized by ¹H- and ¹³C-NMR spectroscopy, and elemental analysis, and the phase behavior of these compounds was characterized and studied by differential scanning calorimetry (DSC) and polarization microscopy. The results indicate that these rod-like compounds exhibit smectic C (S_c) phases. However, for the derivatives with two flexible alkoxy side chains, highly ordered smectic G (S_G) phases were also formed and confirmed by X-ray powder diffraction. The liquid crystallinity of these molecules was attributed to the presence of intermolecular hydrogen bonds involving the NH groups of the heterocyclic rings. The correlation of phase behavior and molecular shape is also discussed.