Dimensional Analysis of Detrimental Ozone Generation by Negative Wire-to-Plate Corona Discharge in Both Dry and Humid Air

A semi-empirical equation is derived to provide a correlation between the ozone generation rate of a negative wire-to-plate corona discharge in both dry and humid air and a series of design/operating parameters. A basic correlation is first derived by applying dimensional analysis on negative wire-to-plate corona discharge in dry air. Further development on the basic correlation is carried out by integrating the influence of humidity. The derived equation is validated by previously reported experimental data and numerical model. The new semi-empirical equation is comprehensive and useful in guiding the design/operation of indoor corona devices under actual ambient operating conditions.     

Effect of chloride ions on the corrosion behaviour of steel in 0.1 M citrate

The corrosion behaviour of steel was studied in aerated near neutral citrate solutions without and with various concentrations of NaCl. The potentiodynamic anodic polarization curve in 0.1 M citrate solution exhibits four anodic peaks A1, A2, A3 and A4 prior to the oxygen evolution reaction. Addition of Cl⁻ ions to the solution enhances the four peaks currents, specially A3, which is followed by pitting corrosion. The negative going scans of the cyclic voltammograms show two anodic reactivation peaks A5 and A6 and one cathodic plateau P1. A diffusion controlled process in the potential range of A1, A2 and P1 was detected by RDE experiments. The potentiostatic current time transients, at different concentrations of NaCl and applied potentials E_a > A3, were studied. The pit nucleation rate (t_i⁻¹) is found to increase with increasing the concentration of NaCl and the applied anodic potential. The impedance spectra exhibit four different behaviours depending on the potential range used. They were fitted with a single time constant circuit at E_a < −700 mV. However, at −700 mV < E_a < −480 mV, they were fitted with a circuit with two time constants. At E_a > −480 mV, the second semicircle is replaced by negative polarization resistance which is disappeared at E_a > −300 mV. The electrode impedance was found to decrease with the applied potential.     

Temperature dependent negative permittivity in solid solutions Sr2Mn1-xSnxO4 (x = 0, 0.3, 0.5)

A few compositions of the system Sr₂Mn_1-xSn_xO₄ (x = 0.0, 0.3, 0.5) were synthesized in the air by the solid-state ceramic route. A change in the sign (positive to negative) of the permittivity above a particular temperature (T_C) is observed at all the measured frequencies. The negative permittivity was analyzed by the Drude-Lorentz model. It was found that negative permittivity is caused by the plasma oscillations of thermally excited free charge carriers. Analysis of XPS spectra confirmed the presence of mixed-valence states of both Mn (Mn⁴⁺ and Mn³⁺) and Sn (Sn⁴⁺ and Sn²⁺) ions. The UV–vis.-IR spectroscopy results indicated generation of a large number of defect states in the forbidden bandgap region of Sr₂MnO₄ on the substitution of Sn at Mn site. Synthesized samples are promising metamaterials for radio frequency (10 Hz -2 MHz) region applications due to the high-temperature plasmonic behavior.     

离子交换色谱法在油田注入水分析中的应用

采用离子交换色谱法测定油田注入水中阴、阳离子含量，分离效果好、重复测定相对偏差小于1％、标样回收率在97％～103％之间、线性范围大于10^2。对现场水样进行测定，其结果与经典化学分析法的测定结果有较好的一致性。     

Flow characteristics of a small moving bed downcomer with an orifice under negative pressure gradient

Behaviour of gas-solid mixtures in a small moving bed downcomer operating under negative pressure gradient has been investigated experimentally, because flow characteristics in a downcomer are important factors in powder handling processes, such as a multi-stage spouted bed or a circulating fluidized bed. In this study, a small downcomer in which the moving bed height could be controlled was employed with the intention of using a downcomer as a connecting tube in a multi-stage spouted bed. Based on experimental observation, the moving bed flow changed from smooth flow (Region(I)) to slip-stick flow (Region(II)) and then changed from slip-stick flow to intermittent flow (Regime(III)), as the gas pressure gradient in the downcomer was increased. In this study, the critical point for steady-state (Region(I)) operation was also examined experimentally and theoretically, by using eight kinds of solid particles (Geldart B, D and A powders) and six different orifice sizes which were used to restrict solids flow at the base of the downcomer. As a result, a correlation of solids flow rate in the stable moving bed downcomer under negative pressure gradient was derived and the critical point between stable and unstable flow was explained by the proposed model.     

Quantification of Pentafluorobenzyl Oxime Derivatives of Long Chain Aldehydes by GC–MS Analysis

Negative ion mass spectrometric techniques, for compounds having good ionization properties, such as pentafluorobenzyl derivatives, are believed to be more sensitive than positive ion methods. Preparation of PFB oximes of fatty aldehydes from crude lipid extracts is problematic due to the release of free aldehydes from plasmalogens during derivatization. Accordingly, in these studies plasmalogens were removed by silicic acid column chromatography prior to pentafluorobenzyl derivatization. This simple purification step to remove plasmalogens is shown to facilitate the quantification of long-chain aldehydes by analysis of their pentafluorobenzyl oxime derivatives utilizing gas chromatography–mass spectrometry in the negative ion chemical ionization mode. The limit of detection for long chain fatty aldehydes using this method is 0.5 pmol and it is linear over two orders of magnitude. Silicic acid column chromatography followed by electrospray ionization mass spectrometry demonstrated that plasmalogens were removed (the detection limit for this analyses was ≤0.3 pmol). Furthermore, we have exploited the utility and sensitivity of this method to identify increases in hexadecanal and octadecanal in 3-amino-1,2,4-triazole treated human neutrophils. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

认知行为综合干预对慢阻肺患者负性情绪的影响

目的探讨认知行为综合干预对慢性阻塞性肺疾病患者负性情绪的影响效果。方法对2008年1～8月在本院治疗的84例COPD患者,根据就诊时间编号,分观察组和对照组,2组患者均按医嘱予以治疗,并给予一般的COPD知识宣教。对观察组选择治疗时与患者及家属进行有效沟通,并采取认知行为综合干预。结果1年后,病人各观察项目经统计学处理,研究组各观察因子明显优于对照组,其中病人生活质量、症状自评量表各因子、药物治疗依从性等因数,除生理功能外,皆有显著意义(P<0.05)。2组患者戒烟情况,研究组为90.5%,对照组为36.4%。结论认知行为综合干预有效控制COPD病人病情进展,减少患者负性情绪,提高COPD患者治疗依从性和生活质量。     

三角槽节流孔角度和孔径对气蚀的影响

为了研究节流孔角度和孔径对气蚀的影响,用FLUENT软件对三角槽节流阀节流孔在角度为8°和2°,阀口开度2mm和0.04mm的压力场进行仿真分析。结果表明:减小节流孔角度和孔径,流场产生低于空气分离压的负压的压差增大,甚至在较高压差下不产生低于空气分离压的低压。该结论对液压泵浮动侧板或配流盘减振槽高压差下抗气蚀设计有参考价值。     

负压力角弧齿离合器铣齿机关键结构设计与加工仿真

负压力角弧齿离合器因承载能力强、啮合性能好、传动可靠性高等优势,被广泛应用于重型卡车驱动桥主减速器总成中。对负压力角弧齿离合器加工用的专用铣齿机的关键部件设计技术进行研究,构建铣齿加工数学模型,根据加工特点开展刀具箱、工件箱的结构功能分析,基于仿真软件建立等效机床模型,编制加工程序完成凸面齿与凹面齿的加工仿真与分析,验证了铣齿机设计方案的正确性。     

Study of the electrochemical hydrogen storage properties of the proton-conductive perovskite-type oxide LaCrO3 as negative electrode for Ni/MH batteries

LaCrO₃ was prepared by glycine combustion method and investigated as negative electrode for Ni/MH batteries. The structures of the as-calcined powder and the 20th charge-discharge cycle sample were characterized by XRD. The electrochemical experimental results demonstrated that the LaCrO₃ electrode showed excellent electrochemical reversibility and considerably high charge-discharge capacity at various temperatures. Except for the charge-discharge cycle at 298 K, the discharge capacities of LaCrO₃ electrode keep steady at 107.1 mA h g⁻¹and 285 mA h g⁻¹ at 313 K and 333 K after 5 cycles, respectively.