Ionic crystals of {[Ni(phen)3]2Ge4S10}·xSol, showing solid-state solvatochromism and rapid solvent-induced recrystallization

Thiogermanates, {[Ni(phen)(3)](2)Ge(4)S(10)}·xSol (Sol = 4MeOH·12H(2)O (1) and 24H(2)O (2)) were prepared and characterized by single-crystal structure analysis. There are large quantities of the solvent molecules that cocrystallize with the anions and cations and form a strong hydrogen bonding network (O-H···S and O···H-O-H···O). Reversible yellow-pink color change with fast speed was found for these compounds, when the crystals were immersed in alcohol solvents and water alternately. The time of the solvent-induced color change relates to the molecular size and structure of the alcohols. The smaller the molecule is, the faster the color change will be. The fastest color change was found by using the methanol solvent that took only about one second. The color change also relates to the ratio of water/alcohol. The solvatochromism phenomenon is accompanied with a rapid solvent-induced recrystallization that is verified by the XRD patterns.     

Enhanced optical absorption by Ag nanoparticles in a thin film Si solar cell

Thin film solar cells have the potential to significantly reduce the cost of photovoltaics. Light trapping is crucial to such a thin film silicon solar cell because of a low absorption coefficient due to its indirect band gap. In this paper, we investigate the suitability of surface plasmon resonance Ag nanoparticles for enhancing optical absorption in the thin film solar cell. For evaluating the transmittance capability of Ag nanoparticles and the conventional antireflection film, an enhanced transmittance factor is introduced. We find that under the solar spectrum AM1.5, the transmittance of Ag nanoparticles with radius over 160 nm is equivalent to that of conventional textured antireflection film, and its effect is better than that of the planar antireflection film. The influence of the surrounding medium is also discussed.     

Generalized Cohomologies and Supersymmetry

We show that the complex cohomologies of Bott, Chern, and Aeppli and the symplectic cohomologies of Tseng and Yau arise in the context of type II string theory. Specifically, they can be used to count a subset of scalar moduli fields in Minkowski compactification with RR fluxes in the presence of either O5/D5 or O6/D6 brane sources, respectively. Further, we introduce a new set of cohomologies within the generalized complex geometry framework which interpolate between these known complex and symplectic cohomologies. The generalized complex cohomologies play the analogous role for counting massless fields for a general supersymmetric Minkowski type II compactification with Ramond–Ramond flux.     

Recent development in SU(3) covariant baryon chiral perturbation theory

Baryon chiral perturbation theory (BChPT), as an effective field theory of low-energy quantum chromodynamics (QCD), has played and is still playing an important role in our understanding of non-perturbative strong-interaction phenomena. In the past two decades, inspired by the rapid progress in lattice QCD simulations and the new experimental campaign to study the strangeness sector of low-energy QCD, many efforts have been made to develop a fully covariant BChPT and to test its validity in all scenarios. These new endeavours have not only deepened our understanding of some long-standing problems, such as the power-counting-breaking problem and the convergence problem, but also resulted in theoretical tools that can be confidently applied to make robust predictions. Particularly, the manifestly covariant BChPT supplemented with the extended-on-mass-shell (EOMS) renormalization scheme has been shown to satisfy all analyticity and symmetry constraints and converge relatively faster compared to its non-relativistic and infrared counterparts. In this article, we provide a brief review of the fully covariant BChPT and its latest applications in the u, d, and s three-flavor sector.     

高斯-谢尔模光束在大气湍流中传输的相干特性研究

文章分析了高斯-谢尔光束在大气湍流中传输时相干长度的变化, 并与真空传输做比较, 真空传输相干长度的变化只与光源参数有关, 大气湍流中传输相干长度的变化受光源参数和湍流的共同影响. 真空传输光束扩展造成相干长度增大; 大气湍流中, 传输距离较短时, 相干长度由于光源扩展而增加, 当传输距离较大时, 湍流效应增强引起相干长度下降. 因此, 单纯从相干长度方面分析大气湍流带来的影响不够完备. 为排除光源扩展影响, 利用相干长度与光斑尺度的比值进行分析, 发现大气湍流会造成比值的下降. 在数值仿真的基础上对上述结果给出了解释. 关键词： 部分相干 大气湍流 高斯-谢尔模 光束扩展     

Qualitative and quantitative analysis of diterpenoids in Salvia species by liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry

An on-line ultra-high-performance liquid chromatography (UHPLC) coupled with photodiode-array detection and quadrupole time-of-flight tandem mass spectrometry (QTOF-MS/MS) method has been optimized and established for the qualitative and quantitative analysis of the important diterpenoids in the methanol extracts of 12 Salvia species. Specific marker components were identified for the classification of the Salvia samples by principal component analysis. The accurate mass measurement within 3 ppm error for all the protonated molecules and subsequent fragment ions offers higher quality structural information for interpretation of fragmentation pathways of various groups of diterpenoids. Thus, a total of 21 diterpenoids from different Salvia species were separated within 10 min, and were unequivocally or tentatively identified via comparisons with authentic standards and literature. This UHPLC-QTOF-MS/MS method was validated to be sensitive, precise and accurate with the limit of detections at 3.0–16 ng/ml, and the overall intra-day and the inter-day variations less than 3%. The recovery of the method was in the range of 96.2–101.8%, with relative standard deviation (RSD) less than 3.0%. The results demonstrated that the qualitative and quantitative differences in diterpenoids were not only useful for chemotaxonomy in some Salvia species but also for the standardization and differentiation of large numbers of similar samples.     

A Simple Model for Nonlinear Confocal Ultrasonic Beams

A confocally and coaxially arranged pair of focused transmitter and receiver represents one of the best geometries for medical ultrasonic imaging and non-invasive detection. We develop a simple theoretical model for describing the nonlinear propagation of a confocal ultrasonic beam in biological tissues. On the basis of the parabolic approximation and quasi-linear approximation, the nonlinear Khokhlov-Zabolotskaya-Kuznetsov （KZK） equation is solved by using the angular spectrum approach. Gaussian superposition technique is applied to simplify the solution, and an analytical solution for the second harmonics in the confocal ultrasonic beam is presented. Measurements are performed to examine the validity of the theoretical model. This model provides a preliminary model for acoustic nonlinear microscopy.     

具有连续纵向激励模态宽带水声换能器研究

摘要分析了连续纵向激励模态拓宽频带的机理。采用单侧激励，可同时激励奇次模态和偶次模态，利用有限元方法研究了这些模态在水中随几何尺寸变化的规律，通过优化设计制作了接近两个倍频程的宽带换能器样品，其工作带宽为12kHz-44kHz，频带内的起伏为±4．3dB。为进一步减少带宽内响应起伏的大小，通过对模态节点间增加质量钢块以及对后盖板采用机械阻抗匹配腔的方式，制作了工作带宽为12kHz-34kHz，频带内的起伏为±3．7dB的宽带换能器样品。     

甲基百里酚蓝-钐(III)配合物与鲱鱼精DNA的相互作用

在pH＝7.25的Tris-HCl缓冲溶液中, 以中性红(NR)作为光谱探针, 采用UV光谱、FS光谱、粘度等方法研究了甲基百里酚蓝(MTB)与稀土金属离子钐[Sm(III)]形成的配合物Sm(III)(MTB)₂与鲱鱼精DNA的作用机制. 确定了Sm(III)(MTB)₂与鲱鱼精DNA之间有嵌插作用方式存在, 说明Sm(III)(MTB)₂金属配合物能使鲱鱼精DNA的功能产生一定影响.     

Crystal Structure of the Samarium Chlorosilicate Sm_3 (SiO_4)_2Cl

1INTR0DUCTIONSofarthreetyPesofstructuresoftherareearthchlorosilicateshavebeenreport-ed:La,(SiO')Cl,t"belongstoorthorhombicsystem,Ln3(SiO'),Cl(Ln=La,Pr)[z'sitomonoclinicsystem,Yb,(SiO'),Cl["toorth0rhombicsystem.WerecentlypreparedthesinglecrystalofSm,(SiO'),ClbyhightemperaturesolidstatereactionandvaportransP0rtmethod.Thoughthesamariumislightrareearthelement,thestructureisisostructuralwithYb,(SiO'),Cl.2EXPERmENTALThetitlecompoundSm,(SiO'),Clwasobtainedasanunexpectedcompoundina…