Hydroxylamine Oxidation on Polycrystalline Gold Electrodes in Aqueous Electrolytes: Quantitative On-Line Mass Spectrometry under Forced Convection

Herein, a method is presented that allows quantitative determination of faradaic efficiencies for dinitrogen (N₂) generation during the electrochemical oxidation of hydroxylamine (NH₂OH), , on a polycrystalline gold Au(poly) disk electrode in aqueous electrolytes over a wide pH range. This tactic involves the use of an impinging jet electrolyte configuration incorporating a gas porous ring connected in turn to a mass spectrometer. The actual amount of N₂ generated at the Au(poly) disk was assayed using the oxidation of hydrazine (N₂H₄) in aqueous phosphate buffer (pH 7). This redox process yields N₂ as the only product, allowing a direct correlation to be established between the changes in the partial pressures of N₂ and the current flowing through the disk electrode. An analysis of the data collected revealed a strong dependence of both on pH and the applied potential. Although values of as high as 20 to 30 % were found in acid and neutral media over a narrow potential region, those in alkaline solution were far smaller in the entire potential range examined.     

锡硫属化物[M(en)3]2[Sn2Se4S2](M=Mn,Co)的溶剂热合成,晶体结构与性质表征

在乙二胺溶剂体系中,180 ℃条件下合成了两种化合物[Mn (en)3]2[Sn2Se4S2](1)和[Co(en)3]2[Sn2Se4S2](2).通过X-射线单晶衍射、SEM、IR、TGA和UV-Vis等手段对其进行了表征.X-射线单晶衍射结果表明化合物1和2是类质同晶,均为正交晶系,并属于Pbca空间群,结构中均含有Sn和两种硫属元素S、Se组成的二聚体阴离子[Sn2Se4S2]2-.两种晶体的晶胞参数分别为:化合物1,a=1.6020(8) nm,b=1.1842(6) nm,c=1.9658(10) nm,Z=8;化合物2,a=1.549t(5) nm,b=1.1688(4) nm,c=1.18666(6) nm,Z=8.紫外-可见漫反射光谱研究结果表明,化合物1和2的禁带宽度分别为1.54 eV和1.64 eV,均有半导体性能.     

制造商竞争环境下逆向供应链的政府奖惩机制研究

主要运用博弈论方法探讨制造商竞争环境下的逆向供应链奖惩机制,建立了5个决策模型,分别是逆向供应链集中式决策、以逆向供应链和不回收再制造的制造商的总利润为目标决策、逆向供应链分散式决策、政府对制造商实施奖惩机制以及政府对回收商实施奖惩机制下逆向供应链的决策模型。研究表明:竞争对回收率提高有益,竞争越激烈回收率越高;积极回收再制造的制造商的新产品零售价较低,具有价格竞争优势;奖惩制造商和奖惩回收商均能起到提高回收率的作用,奖惩力度越大,回收率越高,新产品零售价越低;奖惩制造商比奖惩回收商更能调动制造商和回收商的积极性;奖惩制造商时的回购价高于奖惩回收商时的回购价;在实施奖惩机制时,回收再制造的制造商利润高于不回收再制造的制造商的利润;不回收再制造的制造商的利润随奖惩力度的增大而降低。     

Reflection of plane waves from the boundary of a pre-stressed compressible elastic half-space

The effect of pre-stress on the propagation and reflection ofplane waves in an incompressible isotropic elastic half-spacehas been examined recently by the authors (Ogden & Sotiropoulos,1997). In the present paper the corresponding analysis for compressiblematerials is detailed. In the two-dimensional context consideredfor incompressible materials the (homogeneous) plane waves werenecessarily shear waves. By contrast, in the compressible contextpure shear waves can propagate only in specific directions inthe considered principal plane and, in a general direction,a quasi-shear wave may be accompanied by a quasi-longitudinalwave, as is the case in the anisotropic linear theory. The dependenceof the (in-plane) slowness section on the pre-stress (and finitedeformation) and on the choice of constitutive law is elucidated.This information is used to determine the reflection coefficientsfor reflection of either a (quasi-) shear wave or a (quasi-)longitudinal wave from the boundary of the half-space and tocharacterize the different cases which arise depending on thegeometry of the slowness section. The theoretical results are illustrated by numerical calculationsfor the range of possible types of behaviour with referenceforms of strain-energy function and different states of finitedeformation and to the question of stability of the half-space.     

随机环境中多物种分枝游动质点密度矩阵的极限分布

本文研究了随机环境中的多物种分枝游动于时刻k,位置x的质点密度矩阵序列{M~(k)(x)}k>1的极限分布。我们在证明了M~(k)(x),k>1,x∈Z是k个独立同分布的矩阵值随机元的乘积的基础上,主要证明了随机序列{logM_(ij)~(k)(x)}k>1依某种意义规范后是渐近正态的。     

一类偏积分微分方程二阶差分空间半离散格式的全局行为

偏积分微分方程产生于许多科学与工程领域,数值求解此类问题具有重要应用.本文给出了数值求解一类长时间偏积分微分方程的二阶差分空间半离散格式.借助于Laplace变换及Parseval等式,给出了全局稳定性的证明、误差估计及全局收敛性的结果.     

对多油层油田合理开发程序的初步认识

一个油田,在肯定了它们的工业价值、初步探明了油田的分布面积以后,就要着手迅速地将油田投入开发。但是原油储集在地下的岩层中,油层的地质结构是非常复杂的。要合理开发油田,首先要有一个好的开发方案,要按照油田地下的实际情况确定开发方式、划分与组合开发层系、对不同的开发层系采用不同的井网布置和注水方式等等,力争打较少的井数,得到较好的开发效果。     

8-羟基喹啉衍生化β-环糊精键合硅胶液相色谱固定相的合成与评价

β－环糊精键合硅胶经对甲苯磺酰化后, 与８－羟基喹啉反应得到８－羟基喹啉衍生化β－环糊精键合硅胶固定相（ＱＣＤＳ）． 采用元素分析、热分析及固体核磁波谱对键合固定相进行表征． 考察了ＱＣＤＳ对位置异构体、丹磺酰化氨基酸异构体、苯丙酸类药物和核苷等的分离性能．     

Preparation and Evaluation of Calix[8]arene Bonded Silica Stationary Phase for High Performance Liquid Chromatography

In recent years, calix[n]arenes (n=4,5,6,7,8) as stationary phase have been introduced into the field of chromatography. In our previous works, we have synthesized, characterized and evaluated two different silica-bonded calix[n]arenes (n=4,6) stationary phase, on which the chromatographic behavior of PAHs, positional isomers,nucleosides and bases was investigated. In this paper we report the preparation of calix[8]arene bonded silica stationary phase, and characterization of its structure and chromatographic behavior.