太赫兹光谱提取样品参数降低噪声的方法

为了分析物质的太赫兹光谱信息,给出了从太赫兹时域谱中提取样品光学参数时降低噪声影响的方法.以Zn0.90Cd0.10Te〈110〉单晶样品为例,给出提取该类样品太赫兹波段折射率谱和吸收系数谱的具体计算步骤,并利用mathematica和origin数学软件对实验数据进行分析处理,得到了Zn0.90Cd0.10Te〈110〉单晶的THz波段折射率谱和吸收系数谱.此数据分析过程中考虑了背景噪声的影响,能有效降低背景噪声对实验结果的影响.     

Thermochemical Studies of the Toxic Action of Heavy MetalIons on Escherichia coli by Microcalorimetry

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自然对流对界面形貌、流场和温度场的影响

为了探究固液界面形貌、界面附近流场和温度场与自然对流强度的关系,设计了实验装置,用物理模拟和数值模拟的方法,研究了自然对流强度对透明有机材料固液界面的形貌、界面附近流体速度和温度分布的影响.结果表明,自然对流使固液界面发生弯曲,界面呈不对称形状;靠近固液界面的液体以边界层的方式流动;Rayleigh数较小时,界面附近的液体温度呈线性降低;Rayleigh数较大时,远离界面的液体温度几乎是均匀的,界面处液体温度迅速降低.可见,自然对流强度是影响固液界面形貌、界面附近液体速度和温度分布的重要因素.     

Effects of different CdCl_2 annealing methods on the performance of CdS/Cd Te polycrystalline thin film solar cells

In this paper, the effects of different Cd Cl2 annealing methods, including vapor annealing and dip-coating annealing, on the performance of Cd S/Cd Te polycrystalline thin-film solar cells are studied. After annealing, the samples are lightly etched with 1% bromine in methanol to remove surface oxides. Both annealing methods give Cd Te polycrystalline thin films with good crystallinity and complete structure. For solar cells containing the annealed Cd Te films, cell efficiency first increases and then decreases as the concentration of Cd Cl2 solution used for dip-coating annealing increases, and the optimized Cd Cl2 concentration is 12%. The uniformity of the performance of all cells is analyzed by calculating the relative standard deviation for each parameter. The uniformity of cell performance can be improved dramatically by dip-coating annealing instead of vapor annealing. Most notably, an appropriate concentration of Cd Cl2(12%) acts as a protective layer that is conducive to realizing uniform high-performance Cd S/Cd Te solar cells. According to the location of depletion regions, the Cd Te films treated by dip-coating annealing show a relatively low doping concentration, except for the sample treated with a Cd Cl2 concentration of 6%, which is consistent with the changes of short-circuit current density of the cells. It is believed that these results can be applied to the large-scale production of Cd Te polycrystalline thin-film solar cells.     

Kinetics comparison on simultaneous and sequential competitive adsorption of heavy metals in red soils

To compare the adsorption kinetics of Cu, Zn and Cd introduced into red soils simultaneously and sequentially as well as their distribution coefficients, the ability of red soils to retain heavy metals was evaluated by performing batch experiments. The results indicate that Cu is preferentially adsorbed by red soils no matter in simultaneous or in sequential situation. The adsorption amount of Cd is the minimum in simultaneous competitive adsorption experiment. As heavy metals are added into red soils sequentially, the heavy metal adsorptions are relatively hard to reach equilibrium in 2 h. Red soils retain more Cd than Zn, which is opposite to the result in simultaneous adsorption. The addition sequences of heavy metals affect their adsorbed amounts in red soils to a certain extent. The joint distribution coefficients of metals in simultaneous adsorption are slightly higher than those in sequential adsorption.     

洪泽湖表层沉积物中重金属的分布特征及潜在生态危害

采用变异系数、富集系数、潜在生态危害指数分析评价洪泽湖表层沉积物中的重金属的相关特性。评价结果表明：重金属的空间分布离散性及富集程度存在明显差异,重金属元素空间波动程度依次为Cd〉Cu〉Pb〉As〉Cr〉Zn〉Hg,富集程度依次为Cr〉Zn〉As〉Cu—Pb〉Hg〉Cd;重金属潜在生态危害处于轻微水平,潜在生态危害系数依次为Hg〉As〉Cd〉Cr〉Cu〉Zn〉Pb,洪泽湖南部、东部出湖口表层沉积物重金属潜在生态危害指数较大,网围养殖区受到重金属的轻微污染;Cr,Zn,Pb,Cd污染来源基本一致,对重金属潜在生态危害综合指数影响较大。     

Leaching potential and changes in components of metals in two acidic ferrisols

Two acidic ferrisols, i.e., red soil （RS） and yellow red soil （YRS）, from the vicinity regions of non-ferrous ores in Hunan province of China, were leached with simulated acid rain through artificial column experiments. The results show that the total leaching mass of metals are m（Zn）〉m（Cu）〉m（Cd） from the original soils and m（Cd）〉m（Zn）〉〉 m（Cu） from the contaminated soils with external metals after leaching for 60 d continuously, leaching quantities of Cd and Zn from the contaminated red soil （CRS） are more than that from the contaminated yellow red soil （CYRS）, but for Cu, it is almost the same. The preferential fractions for leaching are mainly in exchangeable forms, and content of exchangeable forms decreases significantly in the contaminated soil profiles. The unstable fractions of Cd, Cu and Zn in the RS and YRS increase significantly with the decrease of pH value of simulated acid rain. Changes of fi, actions of external Cd, Cu, and Zn in the residual CRS and CYRS profiles are significantly affected by the acidity of acid rain, too. After leaching for 60 d continuously, Cd exists mostly in exchangeable form, Cu exists mainly in exchangeable, manganese oxide-occluded and organically bounding forms, and Zn exists in residual in CRS and CYRS profiles. Most of exchangeable Cd and Zn exist only small in surface layer （0-20 cm） and are transferred to the sub-layers, contrarily, Cu accumulates mostly in the topsoil （0-20 cm） with low translocation.     

Thermoelectric properties of p-type (Bi_(0.15)Sb_(0.85))_2Te_3-PbTe graded thermoelectric materials with different barriers

The p-type (Bi0.15Sb0.85)2Te3 and PbTe are typical thermoelectric materials used for low and middle temperature range and functional graded materials (FGM) is an inevitable way to widen the working temperature range. Here two segments graded thermoelectric materials (GTM) consisting of (Bi0.15Sb0.85)2Te3, PbTe and different barriers were fabricated by the common hot pressure method. Metals Fe, Mg and Ni were used as barriers between the two segments. The diffusion of different barriers between the barriers and bases were analyzed by electron microprobe analysis (EMA). The phase and crystal structures were determined by X-ray diffraction analysis (XRD). The thermoelectric properties were measured at 303 K along the direction parallel to the pressing direction. The results show that the compositional diffusion occurs when there is no barrier at the interface of the two segments, and the diffusion of Pb is most obvious; as the barrier material, the diffusion of metals Fe, Mg and Ni between different bases is not very obvious, and the thermoelectric properties of GTM is much better than that of the original segment.     

Rapid Dendrite Growth in Solidification of Highly Undercooled Alloys

Nonequilibrium thermodynamics and transportation kinetics near the propagating solid-liquid interface dominates the rapid solidification process,which is far from a thermodynamically stable state.Rapid solidification process can be described more precisely using quantitative thermodynamic calculation of phase diagram with nonlinear liquidus and solidus and evaluating the nonequilibrium effect in diffusion kinetics.Based on these basic principles,we used a current nonequilibrium dendrite growth model to describe rapid solidification process of deeply undercooled alloys.Evolution of the key fundamental solidification parameters was also evaluated.     

聚合填充法制备UHMWPE/Kaolin复合材料的强流变行为及机理

线性聚乙烯熔体的强异常流动行为源于其高分子量,分子链缠结点多,熔体的界面吸附性强。界面吸附作用的极度变化是造成异常流动的外因,而口模壁附近吸附链和未吸附链间的缠结-解缠结动力学振荡,则是导致挤出压力振荡的内因。用聚合填充法制备的UHMWPE/Kaolin和HDPE／Kaolin体系可以顺利地由毛细管挤出,且填充量增大,体系表现粘度下降,加工流动性变好。在滑动动力学边界条件下,熔体在管壁附近所承受的真实剪切速率和剪应力减少。管壁处粘性作用的下降（脱附）和物料实际承受的弹性变形能减少,是第二光滑区中获得稳定滑动流动的重要条件。     

铝电解阴极过程的电化学研究

用电化学方法研究了在纯冰晶石、工业电解质和低熔点电解质中铝的电解沉积和溶解损失研究表明，铝的沉积为简单的3电子传递反应；铝的再溶解损失由金属／熔液界面层中的稳态传质控制，其速度分别为0．247，0102和0．0423A·cm－2结果证明在低熔点电解质熔液中，电解制取铝具有很高的电流效率．     

离子束溅射制备Bi2Te3热电薄膜

采用离子束溅射技术,溅射不同面积比例的Bi/Te二元复合靶,制备Bi2Te3热电薄膜,所制备的薄膜Bi∶Te原子比接近2∶3.X射线衍射测量结果显示,薄膜的主要衍射峰与Bi2Te3标准衍射峰相同,在(015)晶面上择优选向明显,存在少量的Bi和[Bi,Te]杂质峰.霍尔系数测试及Seebeck系数测量结果表明,薄膜都为n型半导体薄膜,电导率量级为105Sm-1,电学性能良好.在不同条件下制备的薄膜Seebeck系数最大值为-168μVK-1,最小值为-32μVK-1.其中,Bi∶Te原子比为0.69,退火温度为300℃的薄膜功率因子最大,达1.1×10-3Wm-1K-2.     

Optimization of control parameters of CdZnTe ACRT-Bridgman single crystal growth

Cadmium zinc telluride is widely used as a substrate material for CdHgTe epitaxyand efficient γ-detectors. However, it is rather hard to get high quality single crystal ofthis material. One of the key difficulties is the solute content segregation. First, it is noteasy to control the chemical compositions of CdxZn1 Te right exactly due to high-partial ?xpressures of the components. Secondly, its heat conductivity is so low that …     

The steady-state solution of dendritic growth from the undercooled binary alloy melt with the far field flow

The steady-state dendritic growth from the undercooled binary alloy melt with the far field flow is considered. By neglecting the interface energy, interface kinetics and buoyancy effects in the system, we obtaine the steady-state solution for the case of the large Schmidt number, in terms of the multiple variable expansion method. The changes of the temperature and concentration fields, the morphology of the interface, the normalization parameter and the Peclet number of the system induced by uniform external flow are derived. The results show that, compared with the system of dendritic growth from undercooled pure melt, the convective flow in the system of growth from undercooled binary alloy has stronger effects on the morphology of the interface. Nevertheless, the shape of the interface still remains nearly a paraboloid. Supported by the National Basic Research Program of China (Grant No. 2006CB605205) and the National Natural Science Foundation of China (Grant No. 10672019)     

Interfacial reaction between solid nickel and liquid zinc

Interfacial reactions between solid nickel and liquid zinc at 450-650 ℃ for 30-600 s were studied. The morphology and growth behavior of intermetallic compound layers at the interface between solid nickel and liquid zinc were observed and analyzed by SEM and EDS. The results show that γ and 8 phases are formed at 450 ℃ at the Ni/Zn interface, and at 550 ℃ and 650 ℃ only ）,phase is formed at the interthce and some δ phase particles will be participated during solidification on the surface of γphase layer. The β1 phase is absent under experimental conditions. Many cracks occur in the layers due to the difference in thermal expansion coefficients of these phases. It is found that the kinetics of the intermetallic compounds growth follows a parabolic law of time, as controlled by the diffusion mechanism. The apparent activation energies are 113.9 kJ/mol for the growth of γphase and 125.87 kJ/mol for γ1 phase, respectively.     

Mass transfer coefficients in metallurgical reactors

An overview on the application and achievements of physico-mathematical modeling of metallurgical processes in China is briefly declared. The important role of coefficients in model formulation is shown from our experience. The mass transfer coefficients of the slag-metal reactions and the gas-metal reactions are discussed referring to the flow conditions near the interface. The influence of the surface-active species on the mass transfer and the interfacial reaction is also discussed briefly.     

Al2O3对PbTe微观结构和热电性能的影响

为研究Al2O3对PbTe微观结构和热电性能的影响,在Tl0.02Pb0.98Te材料中添加纳米Al2O3粉末,用高能球磨加热压方法制备了Tl0.02Pb0.98Te样品,并对样品进行实验分析。结果表明：添加纳米Al2O3粉末有效地强化了样品高温机械性能;同时,纳米Al2O3颗粒弥散分布在晶界,阻止热压过程中晶粒长大,使晶粒尺寸降低了约50倍;晶粒细化后界面增多,能更好地散射长波长声子;由于晶格热导率降低了约20％,Tl0.02Pb0.98Te（Al2O3）0．06样品的zr在723K时达到1．3。     

Temperature distribution in front of the liquid-solid interface in the undercooled pure melt influenced by a transverse far field flow

The directional solidification in the undercooled pure melt influenced by a transverse far field flow was studied by using the multiple scale method. The result shows that in the boundary layer near the liquid-solid interface, when affected by a transverse far field flow, the temperature distribution in the direction of crystal growth presents an oscillatory and decay front in the side of liq- uid phase. The crucial distinguishing feature of a temperature pattern due to the transverse convection is the additional periodic modulation of the pattern in the growth direction. The wave number and eigenvalue that satisfy the Mullins-Sekerka dispersion rela- tion are suppressed by the transverse far field flow.     

Melt nucleating and the three-dimension steady model of the temperature fluctuation with convection

A three-dimensional steady model of temperature fluctuation with melt convection is studied. It is proved that there exists a unique and stable solution in the model and the solution is expressed in a Fourier series form. It theoretically confirms the mechanism of melt nucleating: as long as the convection with transverse directions exists, the melt temperature on the front of the solidliquid interface would be not only periodical along the direction which is perpendicular to the direction of crystal growth, but also oscillatory and exponential decay along the direction of crystal growth; this oscillatory property, i.e. temperature fluctuation, leads to local supercooling, accelerates local temperature fluctuation and then results in a large number of nuclei.     

便携式重金属分析仪同时分析水中痕量重金属的研究

评价了便携式重金属分析仪利用阳极溶出伏安法的原理分析水中的痕量重金属离子,Cu2+,Pb2+,Cd2+和Zn2+的分析指标,并对干扰Zn2+的因素及去除方法进行了研究.