Nonlinear spectral properties of stimulated Brillouin scattering in plasma

New phenomena in which the stimulated Brillouin scattering (SBS) changes the number and magnitude of frequency shifts in a plasma upon a nonlinear increase in the pumping field intensity are discovered. It is found that the SBS becomes forbidden and then allowed again (upon a subsequent increase in the pumping intensity).     

Exciton condensation in strong magnetic fields

The density correction to the chemical potential of excitons in a strong magnetic field was calculated. The possibilities of Bose-Einstein condensation of excitons and their condensation into electron-hole liquid (EHL) were studied. Magnetic field ranges in which these processes can be observed were determined.     

Effect of a waveguide on induced motion of Josephson vortex chains

The induced motion of vortex chains (helical waves) is studied in a system consisting of a Josephson junction coupled magnetically to a waveguide. The relation between the transport current density and the chain velocity is established.     

Structure of arsenic 8-mercaptoquinolinate: Synthesis and crystal structure of arsenic 4-methoxy-8-mercaptoquinolinate As[C<Subscript>9</Subscript>H<Subscript>5</Subscript>(OCH<Subscript>3</Subscript>)NS]<Subscript>3</Subscript>

Arsenic 4-methoxy-8-mercaptoquinolinate As[C₉H₅(4-OCH₃)NS]₃ (I) was synthesized and studied by X-ray diffraction. Crystals are trigonal: space group R3, a = b = 13.9867(4) Å, c = 12.4991(5) Å, γ = 120°, V = 2117.58(12) ų, ρ = 1.519 g/cm³, Z = 3. An arsenic atom in the crystal structure occupies a special position on axis 3. The structural unit of the crystal (neutral complex I) has symmetry C3. 4-Methoxy-8-mercaptoquinoline acts as a bidentate (N,S-) ligand. The coordination polyhedron of the arsenic atom is a symmetric octahedron (3S + 3N) or, with allowance for the lone electron pair, ψ-one-capped octahedron (3S + 3N + E). Bond lengths are as follows: As-S, 2.3179(7)Å; As…N 2.688(3) Å. The geometries of coordination polyhedra of arsenic atoms are compared in the crystal structures of As(C₉H₆NS)₃, As[C₉H₅(2-CH₃)NS]₃, and As[C₉H₅(4-CH₃)NS]₃.     

Multilevel Coupled Hybrids Made of Porous Cobalt Oxides and Graphene for High-Performance Lithium Storage

Metal oxide coupling with carbon materials holds great promise for lithium storage. Herein, multilevel coupled cobalt oxide–graphene (CoO/CO₃O₄–G) hybrids were fabricated by in situ assembly of Co hydroxide precursors and a calcination process. The oxygen-containing functional groups on the graphene surface act as bridging sites and tend to bond with Co²⁺ ions, effectively modifying the morphology and structure of the Co species. The as-obtained CoO/CO₃O₄–G hybrids are composed of unique CoO/CO₃O₄ porous nanoparticles uniformly anchored on graphene sheets, as confirmed by a series of characterization analyses. Benefiting from these structural characteristics, the CoO/CO₃O₄–G hybrids used as an anode can deliver a high capacity of about 1080 mA h g⁻¹ reversibly at 0.1 Ag⁻¹ in the voltage range between 3.0 and 0.01 V, which is remarkably superior to that of the CoO hexagonal sheets in the absence of graphene. The high reversible capacity of the CoO/CO₃O₄–G hybrids is retained at elevated current densities, for example, a capacity of approximately 455 mA h g⁻¹ can be achieved at a current rate as high as 4 A g⁻¹, indicative of its potential for high-performance lithium-ion batteries.     

Reactions of 3-(4-Aryl-2-thiazolyl)- and 3-(2-Benzothiazolyl)-2-iminocoumarins with N-Nucleophiles

The reaction of 3-(4-aryl-2-thiazolyl)- and 3-(2-benzothiazolyl)-2-iminocoumarins with N-nucleophiles was studied. This reaction gives 2-N-substituted 3-(4-aryl-2-thiazolyl)- and 3-(2-benzothiazolyl)iminocourmarins. N-Nucleophiles such as arylamines, heterocyclic amines, and hydrazine derivatives undergo this reaction.     

计算机模型应用于化学教学的若干策略

学生难以建立宏观-微观-符号三重表征及其它们之间的相互联系,造成大量的化学错误概念及学习障碍。为解决这一问题,国外学者广泛运用计算机模型于化学教学中,并取得良好效果,但国内相关研究相对滞后。论文在实证研究基础上,提炼出计算机模型应用于中学化学的若干教学策略,并结合具体教学案例加以阐述。这些策略包括：（1）创设问题情境,启发学生思维;（2）呈现宏微现象,理解科学知识;（3）训练科学方法,提高探究能力;（4）引导反思质疑,理解模型本质;（5）自主建构模型,增强建模技能。论文最后提出几条教学建议。