Mo2C膜表面粗糙化规律的计算机模拟

引入晶粒边界修正,改进了Mo2C膜表面粗糙化物理模型,将DT2模型推广到包括有温度的情况,对Mo2C膜表面形态进行计算机模拟并统计模拟图的高度分布,确定表面粗糙度随沉积时间和基底温度的变化规律。结果表明：引入晶粒边界修正大大促进了理论与实验结果的一致,Mo2C膜表面粗糙化属快速粗造化,粗造度随基底温度升高而非线性地增大。     

Transport and Helfand moments in the Lennard-Jones fluid. II. Thermal conductivity

The thermal conductivity is calculated with the Helfand-moment method in the Lennard-Jones fluid near the triple point. The Helfand moment of thermal conductivity is here derived for molecular dynamics with periodic boundary conditions. Thermal conductivity is given by a generalized Einstein relation with this Helfand moment. The authors compute thermal conductivity by this new method and compare it with their own values obtained by the standard Green-Kubo method. The agreement is excellent.     

Incorporation of Co(II) in dealuminated BEA zeolite at lattice tetrahedral sites evidenced by XRD, FTIR, diffuse reflectance UV-Vis, EPR, and TPR

A CoSiBEA zeolite is prepared by a two-step postsynthesis method that consists of first creating vacant T-sites with associated silanol groups by dealumination of TEABEA zeolite with nitric acid and then impregnating the resulting SiBEA zeolite with an aqueous solution of Co(NO3)2. The incorporation of Co into lattice sites of SiBEA is evidenced by XRD. The consumption of OH groups is monitored by FTIR. The presence of Co in its II oxidation state and in tetrahedral coordination is evidenced by diffuse reflectance UV-vis and EPR spectroscopy. The very high reduction temperature (1120 K) of cobalt in CoSiBEA zeolite determined by TPR confirms that Co interacts strongly with the zeolite support, consistent with lattice tetrahedral (T(d)) coordination.     

The non-linear dielectric effect in liquid xenon

The non-linear dielectric effect (NLDE), that is the increase in the dielectric constant divided by the square of the applied field, is measured for a number of non-polar molecular liquids and for liquid xenon. The values of the NLDE are compared with results in the literature and with values predicted by theory. The agreement with other experiments is quite good, but with theory is very poor, the only exception being Liquid xenon, where agreement is good. A possible explanation is given. The prediction that the NLDE should increase strongly near the critical point due to the divergence of the isothermal compressibility could not be established by experiment. The conclusion is drawn that this failure is due to the reduction by the theory of second-order effects to first-order thermodynamic and molecular properties.     

Kinetics and mechanisms of the oxidation by permanganate of L-Phenylalanine

The oxidation of L-Phenylalanine by permanganate ion in aqueous phosphate buffers is autocatalized by the inorganic reaction product, which is stabilized in solution by adsorption of phosphate ions on its surface. This product is a soluble form of colloidal manganese dioxide. The rate of the noncatalytic reaction pathway is first-order in both the oxidizing and reducing agent. It is not affected by potassium chloride addition to the solution, but by phosphate addition. The rate increases with the pH of the medium. The autocatalytic pathway is first-order in both permanganate ion and colloidal manganese dioxide, (the permanganate ion according to the Langmuir isotherm). The autocatalytic rate increases with reductant concentration (follows the Langmuir adsorption isotherm). It is not affected by potassium chloride addition to the solution, whereas an increase in the phosphate concentration results in an increase in the rate with the same pH of the medium. Mechanisms consistent with the experimental data are proposed.     

Reversible immobilization of an antibody with a thiol-substituted sorbent : Application to enzyme immunoassays

A new sensor is decribed for a specific protein; enzyme-linked immunosorbent assays are combined with electrochemical measurements. Specific sensors are proposed based on immobilization of an antibody by ligands onto artificial protein-based membranes, combined with a computerized system, for the determination of various antigens or haptens. Specific antibodies labelled by ribonuclease are reversibly bound to the membrane by using cysteine as the ligand. Two enzymes are used: ribonuclease is used for reversibly linking the immuno-complex to the insoluble matrix via disulfide bridges; β-d-glucose oxidase is used for labelling the antigen. The measurement consists of an immuno-logical process and an enzymatic reaction. The protein-based membrane activated with thiol groups is fixed over an oxygen electrode. After incubation of the free antigen and the antigen labelled with glucose oxidase with specific antibodies linked by ribonuclease, the reaction medium is introduced in a continuous flow cell. The oxygen consumption by the enzyme reaction is measured on-line with the electrode in contact with a standard glucose solution. This response is correlated to the antigen concentration of the sample. The signal is directly proportional to the oxygen consumption. The reproducibility with use of the same membrane is <5%. Cleavage between the immuno-complex and the thiol-containing membrane by dithiothreitol is 98% complete.     

Iodometric microdetermination of boric acid and borax separately or in a mixture

Boric acid is determined by first treating it with mannitol and then with solid potassium iodate and potassium iodide. The iodine liberated is titrated with thiosulphate. Borax is determined by reacting it with a known and excessive volume of hydrochloric acid and determining the surplus acid by iodometry. From the amount of acid consumed, the quantity of borax is calculated. Mixtures of borax and boric acid are analysed by combination of the two methods. Borax is determined first, then the mannitol procedure is applied to a second sample and the total boric acid (original plus that produced in the borax-HCl reaction) is determined iodometrically. The boric acid content of the sample is obtained by difference. The procedures can be used for determining 0.01-0.1 mmole of these substances with an average deviation of 0.1-0.4%. The end-points obtained are sharper than those for potentiometric acid-base titrations. Furthermore, the procedures are applicable at much lower concentrations.     

Determination of lead in propellant samples by atomic-absorption spectrophotometry

A procedure is described for the determination of lead in different types of propellant samples by atomic-absorption spectrophotometry. The method is simple, rapid and avoids the use of strong acids and prior sample digestion. Complete lead extraction is achieved with 10% acetic acid. The results obtained by the proposed method are compared with those obtained by the gravimetric chromate method. The variation of the efficiency of lead extraction with sample type is discussed.     

Time dependent solution of the chemical kinetic boltzmann equation: two component isothermal system

A two component reactive systems is studied with the chemical kinetic Boltzmann equation. One components is taken to be in large excess and is unperturbed by reaction. The explicit time dependence of the velocity distribution function of the other component is calculated with a moment method. Comparison is made with the solutions calculated with the Chapman-Enskog procedure and with the method introduced by Kapral, Hudson and Ross. The region of validity of the Chapman-Enskog and/or Kapral, Hudson and Ross solutions is for the elastic collisions rate approximately three orders of magnitude faster then the reactive collisions rate. A comparison with the recent results obtained by Simons is also made.     

借多波长量测数据测定二元配合物组成

本文提出利用多波长量测数据测定二元配合物组成的新方法。首先以线性最小二乘求得各吸收组分吸收系数；继而应用多元线性回归获取各组分平衡浓度并据物料平衡求得配合物组成比及稳定常数。运用单纯形方法对５个体系测定结果进行了检验。     

The semi-micro determination of fluorine,chlorine, and nitrogen in organic compounds: The use of cation exchange resins

The organic compounds are fused in a nickel bomb with sodium in the usual way. If no oxygen is present, the nitrogen is determined as cyanide by Deniges' method. After destruction of cyanide with formaldehyde the total chloride and fluoride is determined by passing the solution through a cation exchange column and determining total acidity in the eluate. The chloride in the same or a separate eluate is then determined by treatment with mercuric oxycyanide or by titration with silver nitrate.     

Effect of introducing acrylic and methacrylic acid groups on molecular relaxation of poly(ethyl methacrylate)

Dielectric and infrared data have been obtained over a wide temperature range on copolymers of ethyl methacrylate with methacrylic and acrylic acid synthesized by radical copolymerization. The dissociation energy ΔH⁰ for the acid dimer in the copolymer is estimated from the temperature dependence of the relaxation strength Δε_α of the α relaxation, which is associated with the glass transition. The value of δH⁰ obtained by this method is in fair agreement with that determined by infrared (IR) spectroscopy. The strength of the α relaxation and its activation energy are both increased by the incorporation of methacrylic acid units but are decreased by acrylic acid units. This behavior is attributed to the restriction of main-chain motions by hydrogen-bonded acid dimers in the copolymers with methacrylic acid and to the incorporation of more flexible links in the copolymers with acrylic acid. The β relaxation observed below the glass transition temperatures is almost unaffected by the incorporation of methacrylic acid.     

Contact line dynamics in drop coalescence and spreading

The dynamics of coalescence of two water sessile drops is investigated and compared with the spreading dynamics of a single drop in partially wetting regime. The composite drop formed due to coalescence relaxes exponentially toward equilibrium with a typical relaxation time that decreases with contact angle. The relaxation time can reach a few tenths of seconds and depends also on the drop size, initial conditions, and surface properties (contact angle, roughness). The relaxation dynamics is larger by 5 to 6 orders of magnitude than the bulk hydrodynamics predicts, due to the high dissipation in the contact line vicinity. The coalescence is initiated at a contact of the drops growing in a condensation chamber or by depositing a small drop at the top of neighboring drops with a syringe, a method also used for the studies of the spreading. The dynamics is systematically faster by an order of magnitude when comparing the syringe deposition with condensation. We explain this faster dynamics by the influence of the unavoidable drop oscillations observed with fast camera filming. Right after the syringe deposition, the drop is vigorously excited by deformation modes, favoring the contact line motion. This excitation is also observed in spreading experiments while it is absent during the condensation-induced coalescence.     

Colorimetric determination of tantalum in titanium alloys

Experimental work on tantalum-titanium alloys has been handicapped by the lack of accurate methods for the determination of the tantalum. In this paper a colorimetric procedure is proposed for the determination. The tantalum is separated completely from the titanium by two tannin precipitations with an intervening digestion with tannin. The tannin precipitate is ignited, fused with potassium bisulfate and the melt taken up with ammonium oxalate solution. Pyrogallol is then added and the intensity of the yellow color is measured. A study was made of the tantalum pyrogallol color to obtain optimum conditions. Elements that would be found in the usual tantalum-titanium alloys do not interfere with the method. More than 0.0025 gram of niobium interferes by cauaing occlusion of titanium by the tannin precipitate. This causes high results for tantalum, since titanium reacts with pyrogallol to produce a yellow color. The presence of more than 0.0050 gram of tungsten causes high results for tantalum because tungsten is partially precipitated by the tannin and reacts with pyrogallol to produce a yellow color. The proposed method is recommended for tantalum-titanium alloys containing 0.05 to 5 percent, tantalum.     

亚铁氰化铜-聚丙烯酰胺/羧甲基纤维素/石墨烯复合水凝胶的制备及铷吸附性能

铷是一种稀贵的碱金属,具有很高的经济价值和广阔应用前景,从卤水中有效提取铷具有重要意义。通过热引发聚合法合成水凝胶基质（聚丙烯酰胺/羧甲基纤维素/氧化石墨烯水凝胶,PCG）固定亚铁氰化铜（KCuFC）,制备了一种新型的铷（Rb⁺）吸附剂（KCuFC-PCG）。采用物理化学方法对KCuFC-PCG的结构和性质进行了表征。通过批量吸附实验,研究了pH值、吸附时间、Rb⁺初始质量浓度、温度和竞争离子对吸附的影响。结果表明,KCuFC-PCG吸附剂在pH值（5～9）范围内表现出良好的吸附能力,pH=8时表现最佳;在Rb⁺质量浓度为5 mg/L,pH=8,吸附6 h达到吸附平衡,KCuFC-PCG的对Rb⁺的吸附量为89.12 mg/g;动力学行为可用准二级动力学模型来描述,表明化学吸附为速率控制步骤;吸附过程符合Langmuir等温吸附模型,为单分子层吸附,最大吸附量为258.4 mg/g。以0.2 mol/L NH₄Cl作为解吸剂,解吸3 h,解吸率为77%。     

A theory of measurement with applications to spectrometry

An analytic function operating on experimental data is optimized for making the most accurate measurement of a parameter of the expected data, under the conditions of non-stationary shot noise. The value of the parameter is obtained by equating the operation on experimental data with the same operation on the expected data which contains the parameter as an unknown value. If the operation is represented by a weighting function, the form of the optimum weighting function depends on the initial transformation of the experimental data by the measuring instrument. The optimum weighting function always contains the derivative of the expected signal with respect to the unknown parameter, divided by the time-dependent variance of the received signal. Weighting functions for the logarithmic output of a spectrophotometer are described. The superiority over least-squares curve-matching is shown. A method for determination of peak position by optimum slope measurement is derived. In general, the optimum weighting function is not a matched filter. The optimum result is the same for center-of-gravity measurements. The optimum parameter measurement is equivalent to a least-squares error minimization weighted by the inverse variance or mean-square noise level. This variance weighting is significant in photometric measurements limited by shot noise or other measurements described by Poisson statistics, such that the mean-square noise level varies with time. The form of the optimum filter, for non-white, non-stationary noise is derived.     

X射线荧光光谱法测定催化原料高岭土化学成分的研究

采用LiBO2熔样,X射线荧光光谱仪测定了高岭土的化学组成,结果表明,测定值与化学法及推荐值相符,重复测定高岭土主、次量组分的相对标准偏差小于0.83%,方法简便快捷,分析时间仅为传统湿法化学分析的1/8,应用于高岭土的测定,结果满意。     

熔盐中熟化处理提高BiFeO3的可见光催化活性

研究发现, 通过熔盐中熟化处理可以显著地提高BiFeO3的可见光催化活性.     

Oxidation of ultra high molecular weight polyethylene (UHMWPE) part 1: Interpretation of the chemiluminescence curve recorded during thermal oxidation

The chemiluminescence curve of polyethylene differs from that of polypropylene even though the oxidation behaviour is similar. The CL curve of PE normally exhibits a double sigmoidal behaviour, whereas PP shows a single sigmoid, and its luminescence intensity is also much lower. It was found, by investigating the build-up of carbonyls and hydroperoxides by means of FTIR, that the first peak coincides with a maximum in hydroperoxide concentration and the second with the build-up of carbonyls. The intensity of the first peak is enhanced by doping the PE with DPA (9,10-diphenylanthracene), which is a chemiluminescence activator, but unaffected by doping the PE with DBA (9,10-dibromoanthracene), which is an energy acceptor. The intensity of the first peak also depends on the presence of carbonyls in the sample. From these observations it is concluded that the CL from PE is a type of activated chemiluminescence, which originates from hydroperoxide decomposition, with carbonyls acting as activator.     

Rapid determination of lead in biological tissues by microsampling-cup atomic absorption spectrometry

Lead can be determined in kidney, liver, and lung tissues by a rapid technique which does not require ashing or acid digestion of the sample. The tissue is homogenized with water, an aliquot of the homogenate is pipetted into a microsampling cup, and lead is determined directly by atomic absorption spectrometry. Calibration is by lead standards in a whole blood matrix. Results correlate well with those obtained by a wet-ashing procedure. The sensitivity (0.01 μg Pb g^-1 wet tissue) permits the analysis of typical tissues with good precision. The procedure is rapid, and its simplicity minimizes the risk of contamination by extraneous lead during sample preparation.