Time-dependent fluctuations in infrared vsCH2 frequencies in acyl chain membranes of Acholeplasma laidlawii cells

We measured FT-IR spectra of intact Acholeplasma laidlawii cells grown at 37 °C on palmitic acid (C16:0) or on binary palmitic acid-d31/oleic acid (C16:0-d31/C18:1(9)) at an initial mole ratio of 2:3, which have been previously reported to produce significant fluctuations in CH₂ symmetric stretching (ν_sCH₂) and CD₂ asymmetric stretching (ν_aCD₂) frequencies (Biochim. Biophys. Acta 1279 (1996) 49). Time courses for acyl chain ν_sCH₂ and ν_aCD₂ frequencies determined from fourth derivative spectra are presented. Fluctuations were detected with the C16:0 enriched cells at temperatures above 40 °C as well as with the cells enriched in 2:3 C16:0-d₃₁/C18:1(9). These observations at temperatures above 40 °C for the C16:0 enriched cells were not in agreement with the conclusion in the previous work by Moore et al. Our results have suggested that the 2850 cm⁻¹ ν_sCH₂ band comprises two components arising from trans and gauche conformations, and that the fluctuations in ν_sCH₂ frequency are caused by random temporal changes in the relative intensities of these two components.     

Real-time measurement of nitric oxide using a bio-imaging and an electrochemical technique

Nitric oxide (NO) is an important mediator responsible for numerous physiological phenomena. Transient levels of NO in biological systems usually range from nanomolar to micromolar concentrations, with a rapid return to basal levels normally seen following these increases. Because NO can diffuse only over a local area in limited time due to such low levels of production and due to its short life-time prior to degradation, high spatial and temporal resolutions are required for direct and continuous NO measurement if the physiological role of NO is to be investigated in any system. For such purposes, analytical methods based on bio-imaging and electrochemical techniques for the measurement of NO are useful. In this paper, we describe the successful application of these methods to a number of biological systems. Specifically, complementary application of these methods demonstrate that it is possible to detect real-time NO production from nervous tissue with high spatial and temporal resolutions.     

固体氧化物电解池直接电解CO2的研究进展

固体氧化物电解池是一种高效、环境友好型的能量转换器件,可以直接将电能转化为化学能. 本文介绍了近年来作者课题组在固体氧化物电解池直接用于CO₂还原的研究进展,并以阴极材料为主着重讨论了金属陶瓷电极和混合导电型钙钛矿氧化物电极的研究工作,最后展望了未来固体氧化物电解池直接电解CO₂的研究思路和方向.     

Difference in Conversions Between Dimethyl Sulfide and Methanethiol in a Cold Plasma Environment

This study compared the conversion of two malodorous substances, dimethyl sulfide (CH₃SCH₃, DMS) and methanethiol (CH₃SH) in a cold plasma reactor. The DMS and CH₃SH were successfully destroyed at room temperature. DMS decomposed less than CH₃SH at the same conditions. In oxygen-free condition, CS₂ and hydrocarbons were the major products, while SO₂ and CO_x were main compounds in oxygen-rich environments. The DMS/Ar plasma yielded more hydrocarbons and less CS₂ than that of CH₃SH/Ar plasma. In the CH₃SH/O₂/Ar plasma, rapid formation of SO and CO resulted in the yields much more amounts of SO₂ and CO₂ than those in the DMS/O₂/Ar plasma; and remained only a trace of total hydrocarbons, CH₂O, CH₃OH, CS₂, and OCS. The major differences between the reaction mechanisms of DMS and CH₃SH were also proposed and discussed.     

Separation of fluorescent 1,N6 ethenoderivatives of diadenosine polyphosphates and their enzymatic degradation products by reversed-phase high-performance liquid chromatography

Summary The retention, selectivity and elution order of fluorescent 1,N⁶-etheno derivatives of diadenosine polyphosphates and their enzymatic degradation products on octadecyl and phenyl-bonded silica columns have been studied as a function of mobile phase pH, ionic strength and organic modifier content. Good separations of the compounds of interest were achieved using mobile phases of around 0.1M potassium phosphate buffers at neutral pH containing approximately 10% methanol or 4% acetonitrile for C₁₈ columns and 5% methanol or 1.5% acetonitrile for phenyl columns. The data obtained were used to establish isocratic assays for diadenosine polyphosphate cleaving activities from chromaffin cells using Di(1,N⁶-ethenoadenosine) polyphosphates as fluorogenic substrate analogues followed by fluorescence detection.     

5-Hydroxytryptamino-induced calcium sparks in cultured rat stomach fundus smooth muscle cells

With the imaging fluorescence probe of Ca2+ (fluo-3) and a laser scanning confocal micro-scope, the spontaneous localized calcium release event was first discovered in resting rat cardiac myocytes by Cheng[1] in 1993. A mathematical simulation is developed with computer in order to reveal the effect, which is immediately suggested that these events are likely to reflect the local-ized release of Ca2+ from a small cluster of ryanodine-sensitive Ca2+ release channels in sar-coplasmic reticulum …     

La0.8Sr0.2Ga0.8Mg0.2O2.8的电化学性质及其在SOFC中的应用

采用凝胶浇注法制备具有较高氧离子电导率的固体电解质La0.8Sr0.2Ga0.8Mg0.2O2.8粉料.X射线衍射结果表明,于1400℃焙烧后即形成了钙钛矿结构,无杂相存在.探讨了粉料压制坯体的致密化和导电性能在1450℃下与烧结时间的关系,发现烧结时间为18h时其相对密度达98.3%,而在24h的情况下,样品具有最佳的氧离子导电性.采用Ni-Ce0.8Gd0.2O1.9作为阳极,La0.8Sr0.2Ga0.6Ni0.4O2.7作为阴极,组装了平板型固体氧化物燃料电池(SOFC).阳极和阴极分别通入含3%H2O的氢气和空气,750℃时的开路电压为1.04V,最大输出功率密度(P)达252mW/cm2(U=0.48V,J=525mA/cm2).     

Effect of polarization on the electrode behavior and microstructure of (La,Sr)MnO<Subscript>3</Subscript> electrodes of solid oxide fuel cells

The electrode behavior and microstructure of freshly prepared (La_0.8Sr_0.2)_0.9MnO₃ (LSM) electrodes were investigated under various polarization conditions. The original, large agglomerates in freshly prepared LSM electrodes were broken down into sphere-shaped grains when exposed to cathodic or anodic current passage of 200 mA cm^–2 at 800 °C in air for 3 h. Microstructural changes under cathodic polarization could be related to the pronounced diffusion and migration of oxygen vacancies and Mn ions on the LSM surface and lattice expansion, while lattice shrinkage under oxidation conditions most likely contributes to the structural changes under anodic polarization. Such morphological changes were irreversible and were found to be beneficial to the performance of freshly prepared LSM electrodes. Freshly prepared LSM electrodes behaved very differently with respect to the cathodic and anodic current passage treatment.