On long waves in shallow water with shear flow

Various evolution equations for long interfacial waves with shear flow are derived with the assumptions that: (1) the wavelength of the interfacial waves is much larger than the total depth of the fluids, and (2) that the spanwise dependence is much weaker than the streamwise dependence. A particular case of interest occurs when the interfacial waves are at or near direct resonance. In this case the Boussinesq equation replaces the Korteweg-de Vries equation. Various special solutions in two dimensions are discussed.     

Estimates for the probability of ruin starting with a large initial reserve

Using the strong approximation of the risk reserve process, the accuracy of the diffusion approximation of the ruin probabilities is studied.     

Chemical forms of cobalt(0) related to polarogrphic and voltammetric catalytic hydrogen currents

The mechanism of catalytic hydrogen evolution at a mercury electrode in buffer solutions containing both bovine serum albumin (BSA) and Co(II) or Co(III) is discussed on the basis of the amount of Co(0) formed on the electrode as well as the solubility of the Co(0) species. An appropriate potential was times t, in ammonia buffer solutions in the presence of Co(III). After the mercury drop was washed with 0.1 M ammonia buffer (pH 9.3) and 1 M hydrochloric acid or concentrated hot hydrochloric acid, the amount of cobalt remaining in and/or on the mercury drop was determined by flameless atomic absorption spectrometry. Amalgamation of Co(0), which is insoluble in the ammonia buffer and 1 M hydrochloric acid, was formed on the electrode, regardless of the electrolysis potential, when t was short. With increase of t, Co(0) changed its characteristics, yielding a Co(0) species [Co(0)_{Group 2}] soluble in 1 M hydrochloric acid but insoluble in the buffer, even though the time required for the change depended on the electrolysis potential. It is demonstrated that Co(0)_{Group 2} plays an important role in the appearance of such catalytic hydrogen currents as the first and second Brdička currents, the P-current of Anzenbacher and Kalous, and i_c of Kolthoff and Kihara.     

Raman excitation profiles,fluorescence spectra and excited state proton transfer of solid 1.8 dihydroxyanthraquinone at 8 K

The single crystal fluorescence spectra as well as the Raman spectra and excitation profiles of solid 1.8 dihydroxyanthraquinone have been measured. Four electronic transitions in the visible range were found: a π—π* active in absorption, a Franck—Condon absorption emission active transition and two emissions due to excited state proton and Hatom transferred configurations.     

Principes pour la préparation de poudres fines par la technique verrière—application a l'hexaferrite de baryum

The “glass synthesis method,” performed in three steps, is widely applicable for the preparation of microcrystalline powders. A glass is first made by fusion of a mixture of a glass-former material F, a modifier M, and a metallic oxide O. Annealing then precipitates microcrystals of MO in a FM glass matrix. The microcrystals are recuperated in the last step by dissolving the matrix. The preparation of hexagonal platelets of BaFe₁₂O₁₉ from the glass B₂O₃ (F)BaO (M)Fe₂O₃ (O) is given as an example. The annealing temperature was found to be the critical parameter to control the grain size of the powder.     

Response of a bar constrained by a non-linear spring to a harmonic excitation

An analysis is presented of the longitudinal response of a bar constrained by a non-linear spring to a harmonic excitation. The method of multiple scales is used to determine equations describing the evolution of the amplitudes and phases with damping, non-linearity and the cases of primary, subharmonic, superharmonic, combination and ultrasubharmonic resonances. These equations are used to determine the steady state responses and their stability.     

Asymmetric transfer hydrogenation of ketones catalyzed by phosphine-rhodium(I) and -iridium(I) complexes

The asymmetric hydrogen transfer from propan-2-ol to prochiral ketones is effectively catalyzed by diphosphine complexes of iridium and rhodium. The influence of the reaction conditions on the activity and selectivity of the catalysts has been investigated.     

10-甲基吖啶苯酚酯衍生物的合成、表征及化学发光特性

吖啶-9-羧酸苯酚酯是一类效率较高的化学发光试剂.其结构一般有两部分组成,吖啶环发光部分和9-羧酸苯酚酯离去基团.本文对离去基团进行修饰,分别在离去基团苯酚部分的2,5或2,6位引入取代基CF₃、NO₂、Br、CH₃,合成了4个新吖啶酯衍生物,并对它们的分子结构进行了表征.4个新化合物和模型化合物(无取代基)比较,均表现出较好的化学发光效率;发光动力学基本符合文献报道规律.而且化学发光法对其水解稳定性考察显示,取代基的电性和位阻是影响稳定性的两大因素.