Patterning polycrystalline aluminum by electropolishing at low voltages

Highly ordered stripes with controllable spacing of the pattern lines are obtained during electropolishing aluminum (Al) foils at low voltage. The samples are investigated in detail with the Atomic Force Microscope (AFM). Stripes with similar spacing of the pattern lines are observed on the surface of Al sheets which are electropolished in the same electrolyte at various voltages. However, the spacing of the pattern lines is closer when there is more ethanol in the electrolyte at the same voltage. The formation mechanism of stripes with dissimilar spacing of the pattern lines in different electrolyte is discussed. We suggest that the spacing of the pattern lines depends on the concentration of the polar molecules (ethanol) in the electrolyte.     

Composition dependence of the photophysical and photocatalytic properties of (AgNbO3)1−x(NaNbO3)x solid solutions

A series of orthorhombic photocatalysts (AgNbO₃)_1−x(NaNbO₃)_x solid solutions have been synthesized by a solid-state reaction method. The composition dependence of the photophysical and photocatalytic properties of synthesized solid solutions has been investigated systematically. With an increase in the content of NaNbO₃, we found that (1) the lattice parameters decreased; (2) the Nb-O bond length in NbO₆ octahedron reduced; (3) the band gap increased; and (4) the mean particle size decreased while the Brunauer-Emmett-Teller (BET) surface area increased. Photocatalytic activities of the (AgNbO₃)_1−x(NaNbO₃)_x (0?x?0.5) samples were evaluated from gaseous 2-propanol (IPA) decomposition into acetone and CO₂ under visible-light irradiation emitted from blue-light-emitting diodes (BLEDs; light intensity: 0.01 mW cm⁻²). Among all the samples, the (AgNbO₃)_0.6(NaNbO₃)_0.4 sample showed the highest photocatalytic activity.     

Selective quantification of doxycycline in human plasma and urine with optimised chromatography

Summary A method for the selective quantification of doxycycline in human plasma and urine has been developed using HPLC with UV-detection at 350 nm. Analyte and internal standard were extracted from plasma by extraction columns filled with octadecylsilica. Urines were only mixed with diluted acid prio to injection. The influence of pH on peak shapes is discussed as well as comparative investigations on selectivity and peak symmetry on commerical octadecylsilica. The method was successfully applied to the samples of a clinical study with an oral single dose of 100 mg. Precision and accuracydata of the assay and calculated pharmacokinetic parameters are presented.     

Co-synthesis of nano-sized LSM–YSZ composites with enhanced electrochemical property

Nano-sized LSM–YSZ composite was co-synthesized by a glycine–nitrate process (GNP). Transmission electron microscopy revealed that the as-prepared LSM–YSZ particles consist of nano-sized powders with a dominant YSZ phase. Backscatter electron image shows that LSM and YSZ phases were regularly dispersed within the composite. Alternating current impedance measurement revealed that the co-synthesized LSM–YSZ electrode shows lower polarization resistance and activation energy than the physically mixed LSM–YSZ electrode. This electrochemical improvement would be attributed to the increase in three-phase boundary and good dispersion of LSM and YSZ phases within the composite. This paper is dedicated to Professor Su-Il Pyun on the occasion of his 65th birthday.     

Conductivity of Sodium Chloride in Water + 1,4-Dioxane Mixtures from 5 to 35°C II. Concentrated Solution

Conductivity data of sodium chloride in binary mixtures of water and 1,4-dioxanefrom 5 to 35°C were measured, covering an electrolyte concentration range upto the limit of solubility in the solvent mixtures and up to 5 mol-dm^–3 inpure water. Data analysis is based on the mean spherical approximation (MSA).Comparison is made with the data representation by the empirical Casteel-Amisequation. The association constants of the MSA are compared with those fromchemical model calculations at low concentrations (lcCM).     

Solid phase extraction conditions for the selective isolation of drugs from biological fluids predicted using liquid chromatography

Summary A new method to predict the most suitable conditions for the solid phase extraction of 1,4-benzodiazepines and related compounds using C18 Sep-Pak carridges is proposed. The composition of the washing and elution solvents for the solid phase extraction of a test compound can be obtained from its capacity factor on a C18 HPLC column and an equation which relates capacity factors and solid phase extraction data of other similar compounds. The solid phase extraction data given in this paper can be used by others, there by saving considerable time and effort in the development of sample preparation methods. The suitability of the method was checked with two test compounds, showing good results.     

Synthesis and electrochemical study of Li-Mn-Ni-O cathodes for lithium battery applications

Cathode powders of the Li–Mn–Ni–O system have been prepared at a Mn/(Mn+Ni) ratio varying from 0 to 1. The solid state reaction method was used to obtain the cathode materials by mixing MnO₂, LiCO₃ and NiO. A 20% excess of lithium was used in the precursors. The materials produced were examined by X-rays to identify their structure. Batteries were assembled by using these materials as cathode with a liquid electrolyte consisting of EC/DC 1:1, 1 LiPF₆ and Li anode. Their capacity, cycle fading and charge-discharge conditions were evaluated.Presented at the 3rd International Meeting "Advanced Batteries and Accumulators", June 16th–June 20th 2002, Brno, Czech Republic     

Features of behavior of solid-state CO<Subscript>2</Subscript> sensors at low temperatures

The dependence of the impedance of low-temperature sensors for carbon dioxide based on the solid-state electrochemical cells Na_0.5WO₃/Na₅GdSi₄O₁₂/SnO₂(Sb₂O₄) on the concentration of carbon dioxide in the air was studied. The reversible change in the sensor resistance was shown to be due to adsorption processes at intergrain boundaries of the solid electrolyte. The composition of the products of the electrochemical processes occurring in the sensors was established. Electronic Publication     

New fluorine-containing plasticized low lattice energy lithium salt for plastic batteries

The synthesis of a new plasticized low lattice energy lithium salt (PLI), structurally related to lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), is described. Incorporation of the plasticizing moiety in a single salt molecule greatly simplifies the solid polymer electrolyte (SPE) processing formulation without compromising performance. Thermally and electrochemically stable polymer electrolyte films of PLI exhibit good ionic conductivity, though somewhat lower than that for LiTFSI. The pentafluorophenyl analog of LiTFSI, prepared by two approaches, exhibits behavior similar to that of LiTFSI.     

LiMn2O4中锂离子扩散系数与充/放电次数的关系

通过容量间歇滴定技术（CITT）对不同电压、不同循环次数下，锂离子在尖晶石LiMn₂O₄中的固相扩散系数进行了研究. 结果表明，锂离子在尖晶石LiMn₂O₄正极材料中的固相扩散系数在3.95 V和4.12 V左右存在两个极小峰，随着循环次数的增加，这两个峰逐渐平坦，并且整体上固相扩散系数呈增大趋势，表明锂离子在LiMn₂O₄中重复脱/嵌时具有自我增强扩散的能力.