Electroanalytical characteristics of ofloxacin in micellar solution

In a pH 6.30 buffer solution containing 0.001% Tween-80, ofloxacin (OFX) gives a sensitive polarographic wave at -1.46 V (vs SCE), which can be used for the determination of OFX down to 10(-8) mol.L-1. The linear range is from 1.39 x 10(-7) to 1.39 x 10(-5) mol.L-1. The proposed method was applied to determination of OFX in urine and serum samples with relative standard deviation less than 7.0%.     

楔横轧件旋转条件的探讨

确保轧件旋转条件,是建立楔横轧正常轧制过程的先决条件。在工艺条件相同的情况下,轧件旋转最困难的区域,不是楔入起始段,也不是楔展宽成形段,而是在楔入段升至最高点前后轧件旋转半周(θ=π)区域内。这不仅为实践所证明,而且导出的旋转条件公式,证明了上述结论。     

Rotatory dorsal subluxation of the navicular: a complication of clubfoot surgery

PURPOSE: We studied serum ELAM-1 levels in colon cancer patients. METHODS AND RESULTS: Serum ELAM-1 levels were significantly higher in 52 patients with colon cancer (mean +/- standard deviation, 69.3 +/- 28.6 U/ml) compared with 32 healthy volunteers (36.5 +/- 11.9 U/ml; P < 0.001). The mean serum ELAM-1 level in patients with metastatic tumors was significantly greater than that of patients with nonmetastatic tumors. Sensitivity and specificity of serum ELAM-1 elevation in detecting metastasis was 75 and 87.5 percent, respectively. Those of carcinoembryonic antigen and carbohydrate antigen 19-9 elevations were 71.4 and 62.5 percent and 35.7 and 91.7 percent, respectively. Twenty-five (89.3 percent) of 28 metastatic tumors showed either serum ELAM-1 or carcinoembryonic antigen elevation. There were weak but significant correlations found between serum ELAM-1 and carcinoembryonic antigen or carbohydrate antigen 19-9 levels. Moreover, serum ELAM-1 increased before detecting the recurrence by imaging in five of seven recurrent colon cancer patients. CONCLUSION: These findings suggest that serum ELAM-1 could be a useful tumor marker for colon cancer, especially in synchronous and metaclonous metastasis.     

Effect of the oxygen content in a salt solution on the characteristics of sodium-reduced tantalum powders

The characteristics of the tantalum powders produced by sodium thermal reduction from salt melts based on K₂TaF₇ and NaCl with various amounts of added oxycompounds K₃TaOF₆ and K₂Ta₂O₃F₆ are studied. At a molar ratio of oxygen to tantalum of 1.25 in the initial melt, capacitor tantalum powders with a specific surface area more than 3 m²/g are produced. The specific capacitance of the anodes made from these powders reaches 58 mC/g.     

变截面连续梁动力特性的半解析解法

求解等跨等截面连续梁的变形和内力是土木工程领域的典型问题. 基于Euler–Bernoulli梁理论,利用位移法和辅助数列推导出任意跨数的等跨等截面连续梁梁端转动刚度的解析表达式,进而得到连续梁支点转角、弯矩在跨中集中荷载、满跨均布荷载、竖向温差作用下的通用计算公式. 研究表明：当跨数趋于无穷大时,等跨等截面连续梁的梁端转动刚度上限值为单跨梁抗弯线刚度的\t\t\t\t\t\t\t\t\t\t\t相似文献   

变截面连续梁动力特性的半解析解法

基于Bernoulli-Euler梁理论,分析了多跨变截面连续梁的动力特性.应用模态摄动基本原理,利用等截面连续梁的模态,将变截面连续梁微分方程的求解转化为代数方程组求解.该方法对于梁的截面函数的连续性要求较少,既适用于截面变化为阶跃形式的梁,也适用于截面函数连续的梁.通过算例分析表明,这一方法可有效地简化计算,同时计算结果具有较高的精度.     

非水滴定法测定硅钙合金中的氧化钙

硅钙合金是一种炼钢脱氧剂,若合金中存在氧化钙杂质对炼钢脱氧效果有影响。本文在加热的条件下,使硅钙合金试样中的氧化钙与乙二醇-无水乙醇提取液中的乙二醇发生反应,生成乙二醇钙（呈弱碱性）,然后以酚酞作指示剂,用苯甲酸标准溶液进行滴定。研究了乙二醇提取硅钙合金中氧化钙的最佳条件,结果表明,以乙二醇-无水乙醇（1+3）作为提取剂,在沸水浴的温度下提取样品,效果最好,氧化钙的测定结果最高且稳定。对样品进行加标回收试验,测得回收率在95.4%～101.9%之间。方法用于硅钙合金样品中的分析,氧化钙测得结果的相对标准偏差小于0.11%。     

Conductimetric titrimetry for assay of selected antibiotics in non-aqueous media

In this study, a conductimetric titration method is proposed for the determination of some commonly used antibiotics. The conductimetric titration of three antibiotics, namely ampicillin, amoxycillin trihydrate and rifampin, was carried out in acetic acid using perchloric acid as titrant. Ciproflaxacin hydrochloride, however, was titrated after being dissolved in acetic acid containing an excess of mercury(II) acetate. For the titration of netilmicin sulphate, barium acetate prepared in acetic acid was used as titrant. The method was found to be highly accurate and precise, having a relative standard deviation of less than 1.0% for all antibiotics studied. It was also shown that the conductimetric titrimetry could be successfully applied to the assay of commercial preparations containing the above-mentioned antibiotics. The validity of the method was tested by the recovery studies of standard addition to pharmaceuticals and the results were found to be satisfactory.     

Selectivity in capillary electrophoresis in the presence of micelles, chiral selectors and non-aqueous media

In addition to high efficiency, short analysis times and small sample volumes, a further attractive feature of capillary electrophoretic techniques is the possibility to achieve, high selectivities. Usually, selectivity control also allows improvement in the resolution. A simple way to enhance the selectivity of capillary electrophoretic separations is to add one or more surfactants above their critical micelle concentration, or in the case of chiral separations to add a chiral selector to the background electrolyte. Because of the dynamic structure of micelles, the aggregation of monomers and size of the micelles can be easily adjusted. This review describes the various type of surfactants used in micellar electrokinetic capillary chromatography, and the chiral selectors employed in enantiomeric separations by capillary electrophoresis. Factors affecting the selectivity are noted. A brief discussion is included of the selectivity enhancement obtainable in non-aqueous media.     

吸湿无机盐－水系的抗蒸发性研究

本文采用直接测量溶液蒸发量的方法，对５种吸湿无机盐水溶液的抗蒸发性及其顺序进行了研究，并分析用其喷洒扬尘路（地）面的抑尘机理，为矿区公路抑尘的实际应用提供参考     

小型电热回转窑的自控设计及应用

介绍小型电热回转窑的自动控制原理和设计,以及在冶金实验室研究中,对要求在不同气氛下进行恒温、恒速控制的焙烧过程中的应用     

NC30Fe合金在氯化钠溶液中的微动腐蚀特性

在PLINT微动磨损试验机上附加电化学测试系统,采用十字交叉接触方式,位移幅值为100μm,法向载荷20、50和80 N条件下,研究NC30Fe合金传热管在氯化钠溶液中的微动腐蚀行为.使用电化学工作站记录微动腐蚀过程中开路电位变化,运用电位扫描法测量微动过程的极化曲线;采用扫描电子显微镜观察磨痕的表面形貌,光学轮廓仪测定磨痕的三维形貌及磨损量.微动磨损使损伤区域金属原子活性增大,腐蚀倾向增大,加速了NC30Fe合金的腐蚀.在氯化钠溶液中,NC30Fe合金由于微动磨损过程产生腐蚀产物膜起到润滑减摩作用,摩擦系数较纯水中降低;但因腐蚀与磨损的交互作用,在氯化钠溶液中的磨损量比纯水中高.氯化钠溶液中的磨损机制主要表现为磨粒磨损和剥层的共同作用.      

非水基凝胶注模成形制备Mo/Cu合金

以球形铜粉和等离子球化钼粉为原料,采用非水基凝胶注模体系制备Mo/Cu合金.研究分散剂用量和固相体积分数对浆料黏度的影响,并对凝胶生坯的干燥、脱脂和烧结进行分析.结果表明:浆料黏度随着分散剂用量的增加先减小后增大,随着固相体积分数的升高而增大.采用丙酮作为液体干燥介质,6 h即可完全脱除凝胶坯体中的残留溶剂.烧结体的致密度随着烧结温度和烧结时间的升高而增大.      

MRI study of non-aqueous phase liquid extraction from porous media

Magnetic resonance imaging is used to investigate, at the pore scale, the dissolution and mobilisation of discrete non-aqueous phase liquid (octanol) ganglia trapped within porous media by capillary forces, by a mobile aqueous phase. Dissolution is observed to be described by a mass-transfer limited model. Mobilisation of entrapped ganglia commences at lower flowrates when a surfactant is introduced into the mobile aqueous phase.     

纳米Mo-Cu超饱和固溶体粉的结构特征及其烧结机制

采用溶胶-喷雾干燥-煅烧-氢还原方法制备了纳米Mo-Cu复合粉末。综合利用XRD、TEM和EDX等检测方法对该Mo-Cu复合粉末的相结构特征和粉末体的烧结机制进行了分析。结果说明:纳米Mo-Cu复合粉末由Mo(Cu)和Cu(Mo)超饱和固溶体组成,但该Mo(Cu)和Cu(Mo)超饱和固溶体呈不稳定状态,随烧结温度升高和保温时间延长,固相Mo(Cu)中析出的Cu逐渐溶解于液相Cu(Mo)中,而液相Cu(Mo)中的Mo逐渐析出沉积在固相Mo(Cu)颗粒上,此过程促进了烧结体致密化。     

渗流作用下风化壳淋积型稀土矿细观孔隙结构演化特征

为研究风化壳淋积型稀土矿浸出过程中溶液渗流作用对孔隙结构的影响,以去离子水为溶浸液开展浸矿实验。对浸出前后矿样进行显微CT扫描,获取了试样内部结构图像,利用阈值分割算法得到了浸出前后稀土矿样的孔隙结构图像。进而,研究了溶液渗流作用下试样孔隙结构的变化特征,分析了渗流作用对试样孔隙率、孔隙体积、孔隙长度、孔隙宽度和孔隙方位角等参数的影响。结果表明:稀土矿孔隙形状和尺寸在渗流作用下发生显著变化,且在粗细颗粒接触区最为明显;溶液渗流作用使得稀土矿孔隙率增大,孔隙总数量减少,孔隙总体积增大。渗流作用下矿样中小孔隙数量减少,大孔隙数量增多,各尺寸区间的孔隙数量变化率随孔隙尺寸的增大呈现先增大后减小的趋势。溶液渗流作用下孔隙长宽比分布更加集中,孔隙方位角在各角度区间的分布更加均匀,孔隙各向异性增强。      

Copper electroplating of non-aqueous elastomeric impression materials: a subjective appraisal of their platability

Adolescent students of a rural block were studied to find out variation in blood pressure in relation to sex, caste and socioeconomic status. Females had significantly higher mean values of blood pressure; both systolic and diastolic. There was significant variation in systolic blood pressure amongst adolescents of various socio- economic classes. Prevalence of systolic hypertension (95 percentile) was higher in adolescents of upper middle social class and diastolic hypertension in Prestige castes. It is suggested that screening for hypertension should be done at school leaving age and high risk adolescents should be advised about periodic check-up, proper diet, salt restrictions and exercise so that frank hypertension could be prevented in adulthood.