冲击电压下残余电荷对沿面放电发展的影响

固体绝缘的表面是高压电力设备绝缘的最薄弱环节,很多绝缘事故都是由沿面放电造成的。发生放电后,电荷会在绝缘表面积聚,会很大程度上影响下一次放电的产生与发展。为此,通过观测在极性交替变化的冲击电压作用下沿同轴圆柱形聚对苯二甲酸乙二醇酯（PET）绝缘表面放电的发展以及测量放电后表面残余电荷电位的分布,来研究残余电荷对沿面放电的影响。研究表明,在改变冲击电压的极性后,由于反极性残余电荷的影响,放电会被促进,放电通道会沿着前一次放电的通道向前发展,并且会比前一次放电距离略长,放电的强度会增强,放电的发展速度也会加快。在沿着放电通道方向,表面电荷电位梯度可以明显分为两部分：在放电头部的20mm区域,电位梯度较大,为流注放电;而在后面的主干部,电位梯度平缓,为先导放电。     

Molecular imprinting under molecular crowding conditions: an aid to the synthesis of a high-capacity polymeric sorbent for triazine herbicides

Molecular crowding, an important feature of the molecular environments in biological cells, was applied to the synthesis of antibody-mimic polymers selective for a group of biologically active compounds, the triazine herbicides. Synthesis of these polymers was conducted using molecular imprinting under molecular crowding conditions, whereby atrazine (a template molecule) was complexed with methacrylic acid (a functional monomer) in the presence of a macromolecular crowding agent (either poly(methyl methacrylate) (PMMA) or polystyrene (PS)) followed by cross-linking with ethylene glycol dimethacrylate. After removal of atrazine from the polymer matrix, the retention properties and selectivity of the resultant polymers were assessed by chromatographic tests. The addition of a crowding-inducing agent resulted in polymers with superior retention properties and excellent selectivity for triazine herbicides, as compared to polymers prepared without addition of a crowding-inducing agent. An imprinted polymer prepared in the presence of PS as a crowding agent exhibited a retention factor for atrazine an order of magnitude larger than that of an imprinted polymer prepared in the absence of a crowding agent. NMR results suggest that the crowding agent is capable of promoting hydrogen bond formation between atrazine and methacrylic acid, which could account for the effect of crowding on molecular imprinting.     

The effect of rebamipide ophthalmic suspension on ocular surface mucins in soft contact lens wearers

Purpose

To evaluate the changes in ocular surface mucins with 2%rebamipide ophthalmic suspension treatment in soft contact lens (SCL) wearers. Rebamipide suspension is a mucin secretagogue approved for the treatment of dry eye syndrome in Japan. In this study, the fluorescence intensity of wheat germ agglutinin conjugate of fluorescein (F-WGA) was used as a marker of membrane-associated mucins, and sialic acid concentration in tear fluids as a marker of secreted mucins.

Long-term clinical effect of nilvadipine in patients with chronic heart failure: a double-blind placebo-controlled study

The long-term effect of calcium channel blockers on chronic heart failure is disappointing, probably because of reflex sympathetic activation through arterial vasodilation. However, nilvadipine may be beneficial for treatment of chronic heart failure since this drug has minimal effects on sympathetic activation. In this study, the effects of 12-week administration of nilvadipine or placebo on symptoms of heart failure and cardiac function were investigated in 23 patients with mild-to-moderate chronic heart failure in a double-blind trial. The patients were randomly assigned to either a nilvadipine group (16 mg daily) or a placebo group. Intergroup comparisons did not show significant differences in any parameters. Serious adverse effects were not observed during the study. Thus, this study failed to show any beneficial effect of nilvadipine in the long-term treatment of patients with chronic heart failure. We conclude that the long-term administration of nilvadipine (16 mg daily) is neither effective nor harmful in the treatment of patients with chronic heart failure.     

Noninvasive recording of pre-P wave related to sinus node electrical activity using P wave-triggered signal-averaging technique

To determine whether the sinus node electrogram (SNE) could be detected noninvasively, a specially modified P wave-triggered signal-averaged electrocardiogram was recorded through the standard V1, V2 and V3 precordial leads in 39 patients. The data between 500 ms before and 300 ms after the trigger point were processed using a digital bandpass filter of 0.5 Hz (12 dB/oct)-20 Hz (18 dB/oct). Pre-P signals were observed just before the P wave resembling SNE recorded directly. Pre-P potential duration closely correlated with direct SACT (r = 0.856, P < 0.0005). Thus, it is believed that signals obtained by this new method would be related to sinus electrical activity and that it could be useful for noninvasive estimation of SACT.     

Oscillatory waveform caused by piezoelectric vibration of pockels crystal and its effective suppression

In measurements of impulse voltages by Pockels sensors, oscillatory components have been observed in the tail parts of the optical signals. In this paper, oscillatory components of Bi₄Ge₃O₁₂ (BGO) Pockels crystals of various shapes are investigated. The tested BGO crystals are rectangular solids, a cylindrical solid, and a tapered quadratic solid. The oscillatory components are derived from the light outputs and the frequency analysis is performed. The oscillation frequency of the rectangular crystals is lower than the theoretical value and that of a cylinder is the same as that of circumscribed rectangular solid. In the case of the tapered BGO crystal, it is possible to reduce the oscillatory components by distributing piezoelectric vibration over a broad frequency bandwidth. © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Planar fractal characteristics of blasted surfaces and its relation with adhesion strength of coatings

Adhesiveness of ceramic coatings is strongly dependent on the surface characteristics of blasted substrates. The roughened surfaces have two types of topographical characteristics, cross-section and planar. The roughened surface is generated by an angled grit-blasting process which can be expected to improve the adhesiveness of ceramic coatings. The topography of the roughened surfaces has fractal characteristics in their cross-section and has been more effectively related to the adhesive strength of ceramic coatings than the average surface roughness traditionally used. This paper presents that fractal characteristics are evaluated in the planar topography of the blasted surfaces and shows again that the planar fractal characteristics are closely related to adhesiveness of ceramic coatings. The planar fractal dimension is evaluated by SIA (Slit Island Analysis) which needs the height data of the roughened surface. These data are obtained by laser-microscope in confocal type.