Fabrication and magnetic properties of arrays of metallic nanowires

Arrays of ferromagnetic nickel and cobalt nanowires have been fabricated by electrochemical deposition of the metals into templates with nanometer-sized pores prepared by nuclear track etching. These systems display distinctive characteristics because of their one-dimensional microstructure. The preferred magnetization direction is perpendicular to the film plane. Enhanced coercivities as high as 680 oersteds and remnant magnetization up to 90 percent have also been observed.     

Separation of metallic from semiconducting single-walled carbon nanotubes

We have developed a method to separate metallic from semiconducting single-walled carbon nanotubes from suspension using alternating current dielectrophoresis. Our method takes advantage of the difference of the relative dielectric constants of the two species with respect to the solvent, resulting in an opposite movement of metallic and semiconducting tubes along the electric field gradient. Metallic tubes are attracted toward a microelectrode array, leaving semiconducting tubes in the solvent. Proof of the effectiveness of separation is given by a comparative Raman spectroscopy study on the dielectrophoretically deposited tubes and on a reference sample.     

Diisopropylfluorophosphate: suppression of ionic conductance of the cholinergic receptor

When frog sartorius muscles were exposed to diisopropylfluorophosphate, the amplitude and half-decay time of the end-plate current decreased; the half-decay time became almost potential-independent and the equilibrium potential for the end-plate current was more negative than during control conditions. When the excess reagent was removed by washing so that only the phosphorylated acetylcholinesterase remained, the amplitude of the end-plate current was restored, while its half-decay time was markedly increased. These findings reveal that this organophosphate significantly affects the receptor-ionic conductance modulator complex in addition to its well-known anticholinesterase activity.     

Responses of leaf stomatal and mesophyll conductance to abiotic stress factors

Plant photosynthesis assimilates CO₂ from the atmosphere, and CO₂ diffusion efficiency is mainly constrained by stomatal and mesophyll resistance. The stomatal and mesophyll conductance of plants are sensitive to abiotic stress factors, which affect the CO₂ concentrations at carboxylation sites to control photosynthetic rates. Early studies conducted relevant reviews on the responses of stomatal conductance to the environment and the limitations of mesophyll conductance by internal structure and biochemical factors. However, reviews on the abiotic stress factors that systematically regulate plant CO₂ diffusion are rare. Therefore, in this review, the rapid and long-term responses of stomatal and mesophyll conductance to abiotic stress factors (such as light intensity, drought, CO₂ concentration and temperature) and their physiological mechanisms are summarized. Finally, future research trends are also investigated.     

Cellular localization of leucine-binding protein from Escherichia coli

Rabbit antibody against lecine-binding protein isolated from Escherichia coli K-12 has been prepared. This antibody has been used in conjunction with enzyme-labeled antibody to allow an immunocytochemical localizati of leucine-binding protein in the Escherichil coli cell. This protein appears to be present only in the envelope and not in the cytoplasm.     

野大麦CIPK基因的亚细胞定位

为明确野大麦CIPK基因在植物亚细胞水平上的定位情况,以已知细胞质膜定位的拟南芥AtCBL1基因和液泡膜定位的AtCBL3基因作为参照,构建了这两个基因分别与红色荧光蛋白基因（RFP）融合的植物表达载体（参照载体）,以及野大麦CIPK基因与绿色荧光蛋白基因（GFP）融合的植物表达载体（目标载体）,利用基因枪转化法将参照载体和目标载体共转化洋葱上表皮细胞,瞬时表达后利用激光共聚焦显微镜进行共定位分析。结果表明,该基因主要定位于细胞膜和细胞核,为进一步深入分析该基因的功能提供了重要依据。     

Corticosteroid responses to limbic stimulation in man: localization of stimulus sites

Corticosteroids in human plasma and urine increase after amygdala stimulation, and plasma corticosteroids decrease after hippocampus stimulation. Five subjects underwent unilateral temporal lobectomy, and histopathologic localization of electrode sites was attempted. Localization was successful for six sites: three in basolateral amygdala and three in hippocampus.     

藏鸡蛋壳通透性与水分散失的关系

为研究藏鸡蛋壳对水的通透性特点和影响因素,分别在西藏林芝地区(海拔:2 90 0m)和北京(海拔:10 0m)同时测定藏鸡和农大小型鸡(平原品种对照)蛋壳对水的通透性等相关特性,分析了在高原孵化时蛋壳失水率与胚胎死亡日龄的关系。结果显示:藏鸡蛋壳对水的通透性(1. 0 5 μg/(d·Pa·g) )显著低于对照品种(1. 2 0 μg/(d·Pa·g) ,P <0 . 0 1) ;蛋壳对水的通透性较低主要由于蛋壳有效气孔面积较小(APT/APD=0 . 5 84 ) ;在高海拔地区藏鸡出雏组在整个孵化期的失水率都显著低于平原对照出雏组(P <0. 0 5 ) ,同一时期死亡较早组的失水率较高。结果表明藏鸡蛋壳通透性较低可能是藏鸡在高原孵化失水率较低的主要因素之一。     

改性凹土对垃圾填埋气中甲烷气体的吸附性能研究

[目的]探讨硅烷偶联剂KH550改性凹土对垃圾填埋气中甲烷气体吸附性能的影响效果。[方法]将凹土经4 mol/L盐酸酸化处理,超声分散后,加入硅烷偶联剂KH550,制备改性凹土。对改性凹土进行扫描电子显微镜分析和傅里叶变换红外光谱仪分析,研究改性凹土对甲烷气体吸附量的影响以及温度对其的影响。[结果]由扫描电镜和红外光谱分析可知,硅烷偶联剂KH550对凹土表面起到了良好的修饰改性作用;经硅烷偶联剂改性后的凹土对甲烷气体的吸附量与改性前相比显著提高,在1 MPa气压下,比改性前提高1倍;在一定温度范围内,改性凹土对甲烷的吸附量随温度升高而降低。[结论]改性凹土能有效去除垃圾填埋气中的甲烷气体,可为进一步工业应用提供依据。     

Tetrodotoxin derivatives: chemical structure and blockage of nerve membrane conductance

The nerve-impuilse-blocking actions of derivatives of tetrodotoxin have been tested on lobster and squid axons. The block produced by deoxytetrodotoxin was similar to that produced by tetrodotoxin and was probably caused by tetrodotoxin contamination. Tetrodaminotoxin and anhydrotetrodotoxin also produced a similar block but at such high concentrations that tetrodotoxin contamination cannot be ruled out. The hydroxyl group of C(4) and the hemilactal oxygen links play an important role for the nerve-blocking action.     

细菌产壳聚糖酶的性质初探

甲壳低聚糖(chitooligosaccharides)具有抗菌、抗癌以及促进双歧杆菌增殖、增强机体免疫等功能[1]。目前制取方法常用盐酸水解壳聚糖来制备,但该法反应条件较难控制,不易得到较高聚合度的低聚糖,对环境污染严重。已有学者研究利用壳聚糖酶水解壳聚糖来制备甲壳低聚糖,由于其专一性强,反应条件温和,得率高,且不污染环境,已得到广泛的关注。自从上世纪七十年代初期,Monaghan等[2]首次报道B.bassiana中存在壳聚糖酶(chitosanase,EC.3.2.1.99)以来,已在许多细菌、放线菌和真菌等微生物中发现了该酶。MasahiroKurakake等[3]对Bacilluscere…     

Granites: Relation of Properties in situ to Laboratory Measurements

The velocity of compressional waves and electrical resistivity in granite in situ measured in two 3-kilometer boreholes exhibits very little variation with depth, in contrast with the variation predicted from laboratory measurements on dry samples. These observations can be explained either by the absence of small open cracks in the rocks in situ or by the effects of complete saturation with water. The seismic velocities of many granites at shallow depths in the earth's crust may be significantly larger than was previously believed. Other properties are also affected; correction for the effect of cracks on thermal conductivity raises the average heat flow in shield areas by as much as 20 percent.     

细菌产壳聚糖酶的性质初探

甲壳低聚糖(chitooligosaccharides)具有抗菌、抗癌以及促进双歧杆菌增殖、增强机体免疫等功能[1]。目前制取方法常用盐酸水解壳聚糖来制备,但该法反应条件较难控制,不易得到较高聚合度的低聚糖,对环境污染严重。已有学者研究利用壳聚糖酶水解壳聚糖来制备甲壳低聚糖,由于其专一性强,反应条件温和,得率高,且不污染环境,已得到广泛的关注。自从上世纪七十年代初期,Monaghan等[2]首次报道B.bassiana中存在壳聚糖酶(chitosanase,EC.3.2.1.99)以来,已在许多细菌、放线菌和真菌等微生物中发现了该酶。MasahiroKurakake等[3]对Bacilluscere…     

淡紫拟青霉角蛋白酶特性初步研究

【目的】对淡紫拟青霉PL-HN-16角蛋白酶的酶学特性进行初步研究。【方法】以鸡毛(黄色和黑色)、鹅毛、猪毛角蛋白为发酵底物,并作为培养基中的惟一氮源,观测发酵液的变化及培养液中的角蛋白酶活性,同时以鹅毛为发酵底物,对淡紫拟青霉角蛋白酶粗酶的最适作用温度和pH进行了初步研究。【结果】PL-HN-16对鸡毛、鹅毛、猪毛均能降解,PL-HN-16角蛋白粗酶最适作用温度为40℃、最适pH为8.0。【结论】在最佳作用温度与pH条件下,PL-HN-16角蛋白酶活性为41U/mL,PL-HN-16对不同发酵底物的降解活性不尽相同。     

钝顶螺旋藻藻胆蛋白性质的研究

采用羟基磷灰石柱层析法对钝顶螺旋藻藻胆蛋白粗提液进行纯化,得到藻蓝蛋白（PC）和别藻蓝蛋白（APC）纯化液。用紫外-可见分光光度计测得PC和APC的最大可见吸收峰分别在620　nm和650　nm处;用荧光分光光度计测得它们的室温荧光发射峰分别在645　nm和656　nm处。经12% SDS-PAGE法分析,PC由α和β两个亚基组成,其分子量分别为16.3　kD和18.9　kD;APC也由α和β两个亚基组成,其分子量分别为15.0　kD和16.9　kD。用高效液相色谱仪(HPLC)对PC和APC的氨基酸组成作了测定,发现二者的氨基酸组成比较相似。     

Internally perfused axons: effects of two different anions on ionic conductance

Voltage-clamizped giant axons of squid, internally perfused with potassiumt chloride solutions, showed reduced initial transient memnbrane conductance to voltage and increased overall (leakage) conductance. Unclamtped axons showed reduced action and resting potentials. Ionic conductances and memtbrane potentials were maintained or restored by perfusion with potassiuwn fluoride solutions. As much as 90 percent of internal fluoride could be replaced with chloride without alterationt of normal properties of membrane.     

Mediation of responses to calcium in taste cells by modulation of a potassium conductance

Calcium salts are strong taste stimuli in vertebrate animals. However, the chemosensory transduction mechanisms for calcium are not known. In taste buds of Necturus maculosus (mud puppy), calcium evokes depolarizing receptor potentials by acting extracellularly on the apical ends of taste cells to block a resting potassium conductance. Therefore, divalent cations elicit receptor potentials in taste cells by modulating a potassium conductance rather than by permeating the cell membrane, the mechanism utilized by monovalent cations such as sodium and potassium ions.     

Tissue factor (thromboplastin): localization to plasma membranes by peroxidase-conjugated antibodies

Peroxidase-conjugated antibodies were used to determine the histologic and cytologic localization of bovine and human tissue factor (thromboplastin). Tissue factor antigen was found in highest concentration in the intima of blood vessels, particularly in the plasma membranes of endothelial cells and in human atheromatous plaques. Tissue factor was also found limited to the plasma membranes of many cell types. The presence of tissue factor in the plasma membranes of endothelial cells and atheromata suggests that it may play a significant role in hemostasis and thrombosis.     

Amantadine: neuromuscular blockade by suppression of ionic conductance of the acetylcholine receptor

Amantadine hydrochloride decreases the sensitivity of denervated mammalian muscle to iontophoretically applied acetylcholine. The drug depresses the amplitude of the end-plate current and reverses the slope of the relation between half-decay time and membrane potential suggesting that it alters the ionic conductance that is mediated by the acetylcholine receptor. Binding studies confirm that amantadine acts on the ion conductance modulator rather than the acetylcholine receptor.