辐照三烷基氧化膦萃取锶和铯的研究

研究了γ辐照后的３０％％ＲＰＯ－煤油－ＨＮＯ３体系萃取Ｓr和Ｃs的性能。利用ＩＣＰ－ＡＥＳ及ＡＡＳ分别测定两相中Ｓr和Ｃs浓度，分配比。试验了辐照剂量对分配比的影响。结果表明，γ射线辐照对ＴＲＰＯ的萃取笥能无显著影响。     

FRACTURE ASSESSMENT OF AN INTERFACE CRACK BETWEEN TWO DISSIMILAR MAGNETOELECTROELASTIC MATERIALS UNDER HEAT FLOW AND MAGNETOELECTROMECHANICAL LOADINGS

A magnetoelectrically permeable interface crack between two semi-infinite magnetoelectroelastic planes under the action of a heat flow and remote magnetoelectromechanical loadings is considered, where the assumption of frictionless contact between two dissimilar halfplanes is adopted. Not only the solutions of the interface crack problem are presented in an explicit form, but also the general condition for the transition from a perfect thermal contact of two magnetoelectroelastic bodies to their separation is given.     

Two-Parameter Stochastic Resonance in a Model of Electrodissolution of Fe in H_2SO_4

IntroductionStochastic resonance (SR) is a nonlinear effect which describes the optimal detection of a weak periodic signal by the action of external noise in nonlinear systems. SR was originally proposed to account for periodicity in the Earth's ice ages1, and it has been observed in a wide range of biological2-4 , physical5 and chemical6 systems. The systems mentioned above which may give rise to SR have a denominator despite many examples of SR in different scientific areas. It is noted…     

Surface-functionalized Carbon Black as Catalyst for the Direct Production of Hydrogen Peroxide by the Oxidation of Hydroxylamine

Carbon black (CB) without micropores was functionalized by mixed acid and used to explore the surface chemistry effect on the production of hydrogen peroxide (H₂O₂). The CB materials were characterized by N₂ adsorption‐desorption, XRD, SEM, FTIR, and TPD. The results of different characterization methods indicated that both the textural features and the surface chemical properties of CB were significantly modified by the acidic treatment. The catalytic performance of the modified CBs for hydroxylamine (NH₂OH) oxidation increased with increasing the surface oxygen‐containing species. The yield of H₂O₂ approached 30% with the corresponding concentration of 73.9 mmol·L^?1 (w=0.25%) over the most promising CB catalyst, which was much superior to the results obtained on supported noble metals. Correlations between catalytic activity and concentration of different surface functional groups on the CB samples confirmed that the quinonoid species might be the active species.     

Intersubband optical absorption in two-level quantum wells embedded in a planar microcavity

A theoretical analysis of the optical absorption including both the linear and third-order non-linearity arising from intersubband transitions in two-level quantum wells, which are embedded in a planar microcavity, has been performed. Starting from the Maxwell–Lorentz equations, the expressions of the field in each layer are explicitly given, and the field in the quantum wells is determined via an integral equation, in which the third-order non-linearity is included. Then, by matching the boundary conditions, the field in the quantum-well microcavity structure is rigorously determined, and the absorption coefficient is thus obtained. Detailed numerical calculations show that the optical intersubband absorption can be significantly modified due to the coupling between the quantum wells and the microcavity. This revised version was published online in November 2006 with corrections to the Cover Date.     

Optimum convective heat transfer coefficient for diode-pumped laser slabs

It is important for laser designers to study the characteristics of heat transfer from the laser crystal slab to the coolant in high-power DPSS laser operations. We have simulated and obtained the optimum heat transfer coefficient and coolant flow rate for our cavity design, in which the circulating coolant is maintained at a constant temperature. It has been determined that the coolant temperature and the convective heat transfer coefficient (h) are important parameters in the thermal analysis. The coefficient h is affected by the coolant flow rate, the physical properties of the laser slab and the coolant and the pumping cavity geometry. Using analytical heat transfer equation, for cooling water temperature of 300 K, the optimum flow rate for our cavity geometry is found to be 390 cm³/s, corresponding to h=5 W/cm² K.     

富Ca富Cu的Bi(Pb)-Sr-Ca-Cu-O超导电性

采用普通固态反应法制备了名义组分为Bi_2.0-xPb_xSr_1.9Ca_2.2Cu_3.3O_y超导体,并系统研究了样品的X射线衍射谱。结果表明:富Ca富Cu加速了2223相形成,拓宽了Bi系的单相化烧结温区,并获得了品质优良的110K单相多晶样品;低温退火有助于提高样品的单相化程度。 关键词：     

Existence and uniqueness of local solutions to a class of quasilinear degenerate parabolic systems

In this paper, the authors study an initial and boundary value problem to a system of evolution p-Laplacian equations coupled with general nonlinear terms. The authors use the method of regularization to construct a sequence of approximation solutions with the help of monotone iteration technique and hence obtain the existence of solutions to a regularized system of equations. Then the existence of solutions to the system of evolution p-Laplacian equations is obtained with the use of a standard limiting process. The uniqueness of the solution is also proven.     

Fluorescence feedback control of a diode pumped solid state laser

We implement active feedback control in a Q-switched diode-pumped Nd:YVO₄ laser by monitoring the fluorescence intensity from the laser crystal. When the initial inversion level indicated by the detected fluorescence has reached a predetermined value, Q-switching is initiated. The Q-switched pulse energy is stabler with our feedback scheme based on the fluorescence intensity than that with the conventional Q-switching when pumping source is not stable.     

Mn、Ti掺杂对NaxCoO2体系超导电性和电荷有序化影响

本文研究了Mn、Ti掺杂对Na0.3Co1-xMxO2·1.3H2O超导电性和 Na0.5Co1-xMxO2材料电荷有序现象的影响.我们成功合成了Na0.7Co1-xMxO2(M= Mn和Ti,0≤x≤0.1)系列样品,并采用不同强度氧化剂氧化脱钠,分别获得Na0.5Co1-xMxO2和水合物Na0.3Co1-xMxO2·1.3H2O (0≤x≤0.1, M= Mn和Ti).X射线衍射分析表明所有样品都是比较好的单相,它们的晶格常数随着Ti和Mn的含量发生系列变化.物性检测显示Na0.3Co1-xMxO2·1.3H2O的超导电性随着Mn和Ti掺杂量的增加明显减弱,在Mn掺杂为x=0.02 或Ti掺杂为x=0.01时其超导电性消失;磁性检测发现随着掺杂量的增加,Na0.5Co1-xMxO2电荷有序态被逐渐破坏,其中掺Mn比掺Ti对电荷有序化行为的影响更为明显.