An Integrated Two Phases Approach to Zn2+ Ions Electroreduction on Hg

The following two numerical models have been applied to zinc cations electroreduction in 1 M NaClO₄ water solution: a classical EE model describing the concentration of involved species in solution (semi infinitive diffusion region), an extended EE model describing both: the concentration of involved species in solution and the concentration of metallic zinc inside mercury drop (in limited area of diffusion). In the latter model the inner part of mercury drop and surrounding solution were treated as dynamic interrelated system. Both models were applied to experimental cyclic voltammetric CV data in 1 M NaClO₄, the results compared and discussed. The concentration profiles of all species including metallic zinc inside mercury drop were performed. The presented integrated model is essential for theoretical and analytical aspects of the electrochemistry of mercury soluble metal cations and amalgams.     

Monte Carlo study of interfacial silicon suboxide layers and oxidation kinetics

A simple simulation scheme that simultaneously describes the growth kinetics of SiO₂ films at the nanometer scale and the SiO_x/Si interface dynamics (its extent, and spatial/temporal evolution) is presented. The simulation successfully applies to experimental data in the region above and below 10 nm, reproduces the Deal and Grove linear-parabolic law and the oxide growth rate enhancement in the very thin film regime (the so-called anomalous region). According to the simulation, the oxidation is governed mainly by two processes: (a) the formation of a transition suboxide layer and (b) its subsequent drift towards the silicon bulk. We found that it is the superposition of these two processes that produces the crossover from the anomalous oxidation region behavior to the linear-parabolic law.     

Proton conductivity of phosphoric acid derivative of fullerene

The proton conductive property of methano [60] fullerene diphosphoric acid has been investigated under various humidity conditions at the temperature range between 15 and 45 °C. It shows proton conductivity as high as 10⁻² S cm⁻¹ at 25 °C under relative humidity of 95%. Thermal analyses including TG–DTA and thermal desorption mass spectroscopy (TDS) confirm that the compound is thermally stable up to 200 °C. Proton conduction of the compound depends very much on humidity or water content. The logarithmic conductivity at 25 °C is increased linearly with increasing relative humidity. The activation energy (E_a) estimated from the slope of log(σT) vs. 1/T is decreased from 1.08 to 0.52 eV, as the relative humidity is increased from 40% to 75%. The humidity dependence of conductivity is discussed in the light of the observed hydration isotherm.     

Comparison of growth stress measurements with modelling in thin iron oxide films

High temperature oxidation of metals leads to residual stresses both in the metal and in the growing oxide. In this work, the evolution of this residual stresses is theoretically predicted in the growing oxide layers. The origin of these stresses is based on a microstructural model. Using experimental results providing from the oxidation kinetics, and an analysis proposed to describe the growth strain occurring in the thin layers, a set of equations is established allowing determining the stresses evolution with oxidation time. Then, the model is compared with experimental results obtained on both α-Fe and phosphated α-Fe, oxidised at different temperatures. Numerical data are extracted from experiments either with an asymptotic formulation or with an inverse method. These two methods give good agreement with experiments and allow extracting the model parameters.     

改进型磁绝缘线振荡器的设计和数值模拟

 综合两种现有磁绝缘线振荡器的优点，对器件进行改进，将双渐变结构、轭流片和阻抗渐变三种增大功率的机制综合考虑，利用二维半全电磁PIC程序进行数值模拟，设计了一种新的改进型磁绝缘线振荡器，当外加电压为550kV，电流为35kA左右时，在L波段获得了6GW的峰值输出功率。     

Theoretical Study on the Reaction Mechanism between Dichlorocarbene and Armchair Single-walled Carbon Nanotubes

1 INTRODUCTION Carbon nanotubes have many potential applica- tions due to their unique structures and properties[1～4]. Physicists have been studying their electrical, me- chanical and other properties since their discove- ries[5, 6]. Recently, chemists are interested in carbon nanotubes because their properties can be altered by chemical functionalization[7～14], and these functiona- lized nanotubes can undergo further chemical trea- tment. So the potential application range of such na- …     

A theoretical study of the ion pair SN2 reaction between lithium isocyanates with methyl fluoride with inversion and retention mechanism

This paper is devoted to a detailed theoretical study of an ion pair S_N2 reaction LiNCO+CH₃F in the gas phase and in solution at the level of MP2(full)/6-31+G**//HF/6-31+G**. Two possible reaction mechanisms, inversion and retention, are discussed. There are eight possible reaction pathways. The inversion mechanism is more favorable no matter in the gas phase or in solution based on analyses of the transition structures. Methyl isocyanate should form preferentially in the gas phase and more stable methyl cyanate is the main product in solution. The retardation of the reaction in solvents was attributed to the difference in solvation in the separated reactants and in the transition state.     

Evidence of a Photo‐Radical Pathway Responsible of the Rearrangement of a Manganese(III)‐Schiff Base Complex in Solution

A new Mn^III‐Schiff base complex, [MnL(OH₂)](ClO₄) ( 1 ) (H₂L = N, N′‐bis‐(3‐Br‐5‐Cl‐salicylidene)‐1, 2‐diimino‐2‐methylethane), an inorganic model of the catalytic center (OEC, Oxygen Evolving Complex) in photosystem II (PSII), has been synthesized and characterized by elemental analysis, IR and EPR spectroscopy, mass spectrometry, magnetic susceptibility measurement and the study of its redox properties by cyclic and normal pulse voltammetry. This complex mimics reactivity (showing a relevant photolytic activity), and also some structural characteristics (parallel‐mode Mn^III EPR signal from partially assembled OEC cluster) of the natural OEC. The complex 1 was found to rearrange in solution into a crystallographically solved square‐pyramidal complex, [MnLL′] ( 2 ) (HL′ = 6‐bromo‐4‐chloro‐2‐cyanophenol), through a process, which probably liberates radical species (detected by EPR), and provokes a C—N bond cleavage in the ligand. A photo‐radical mechanism is discussed to explain this rearrangement.     

具有控制系数的高阶线性微分方程复振荡的一个结果

该文考虑具有控制系数 A\-0 和系数仅有有限个极点的高阶线性齐次微分方程（1.1）。得到了一个复振荡结果，该结果是J. K. Langley［11］等作者在整系数下相应结果的推广。     

Dicyclopentadienyl complexes of titanium,niobium, and tungsten in the controlled synthesis of poly(methyl methacrylate)

Organometallic compounds Cp₂TiCl₂, (EtC₅H₄)₂NbCl₂, and (PrⁱC₅H₄)₂WCl₂ were assessed as additives that control polymer chain growth in the polymerization of methyl methacrylate. In the presence of compounds mentioned in amounts comparable with that of the initiator, a uniform process with no gel-effect occured and respective linear increase in the molecular weight of the polymer up to high degrees of the monomer conversion was observed.