超声条件下水合肼还原制备纳米铜粉

在超声条件下以五水硫酸铜为原料,水合肼为还原剂,OP为表面活性剂,氢氧化钠为pH调节剂,制备了分散性较好的球形纳米铜粉.研究了Cu2 外的初始浓度,超声时间,超声功率,超声周期等因素对铜粉粒度及形貌的影响.用SED、TEM及XRD对产品进行表征.结果表明:所制备的铜粉呈球形、粒径分布窄、表面未氧化,平均粒径约为40 nm.     

表面活性剂对纳米三氧化钼形貌的影响

以仲钼酸铵和硝酸为原料,在超声波作用下,通过加入不同表面活性剂,采用均匀沉淀法制备了纳米级三氧化钼。研究了表面活性剂种类及用量等因素对产物纳米MoO3的影响,采用X射线衍射仪(XRD)及扫描式电子显微镜(SEM)对产物的结构及形貌进行了了表征。实验结果表明:在液相法制备纳米三氧化钼的过程中,表面活性剂可有效抑制三氧化钼颗粒的长大和团聚,阴离子型表面活性剂的分散性能优于阳离子和非离子表面活性剂。在仲钼酸铵溶液浓度为0.16 mol.L-1,阴离子表面活性剂十二烷基苯磺酸钠(DBS)浓度为1.8 mmol.L-1时,可制备出粒径为50 nm左右的球形纳米三氧化钼。随着阴离子表面活性剂十二烷基苯磺酸钠(DBS)浓度的增大,产物纳米三氧化钼的形貌由球形转变为束状、层状。     

表面活性剂在纳米八钼酸铵制备中的应用

重点探索了表面活性剂在纳米八钼酸铵制备中对产品粒径的影响效果和在纳米八钼酸铵制备过程中表面活性剂的选择，通过实验获得最佳的阴离子表面活性剂。     

纳米氧化锌的均匀沉淀法制备工艺研究

介绍了以醋酸锌与尿素为原料,添加表面活性剂,均匀沉淀法制备纳米氧化锌的新工艺.讨论了反应物浓度的配比、反应浓度、反应时间、表面活性剂对纳米氧化锌形成的影响.采用X射线衍射(XRD)、激光粒度分析仪、热分析、扫描电镜等方法对制备纳米氧化锌进行表征,结果表明:制得的氧化锌的平均粒径为52 nm,晶型为六方晶系.     

超细铜粉的新型电沉积制备及表征

采用对电解液进行超声分散的新型电沉积法,制备超细铜粉,借助X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)和激光粒度分析(SL)对所得粉末进行表征,研究电解液中Cu2+浓度对粉末形貌、粉末粒径以及电流效率的影响,深入探讨粉末的形成机理.结果表明:所生成的粉末为fcc结构的单质铜;取决于乳化液中表面活性剂的分布,粉末具有鱼骨状和不规则状两种形貌;随着电解液浓度从0.03 mol/L增加到0.09 mol/L,铜粉的平均粒径从0.92 μm线性增加到1.8 μm,电流效率从65.5%线性提高到91.3%.     

阴极旋转电解法制备纳米铜粉的实验研究

本文介绍了一种阴极旋转电解法制备纳米铜粉的方法.通过正交实验得出了电流密度、H+浓度、Cu2+浓度最佳参数,研究了分散剂、阴极板转速对制粉的影响,并对其原理进行了分析.制备出了粒径在20～50 nm,形貌近似球形的纳米铜粉.     

铜粉对MIM钨铜合金组织和性能的影响

采用金属注射成形（MIM）技术制备了钨铜合金,定量表征了铜粉的粉末粒度和粒形,重点研究了铜粉粒度和粒形对MIM钨铜合金组织与性能的影响。通过对比铜粉的粒径、粒度分布宽度、长宽比、粗糙度、赘生物指数和钝度等特征参数,破碎铜粉与水雾化铜粉颗粒呈枝晶状,粒径远小于还原铜粉,但破碎铜粉粒度分布宽,微观结构上的规则度、表面光滑程度以及分散程度最佳。破碎铜粉混合钨粉为原料,通过MIM技术制备钨铜注射生坯致密度高、缺陷少,烧结后钨铜合金的组织与性能最优,致密度为96.2%,硬度为235HV,抗弯强度为1 200 MPa,热导率为128 W/(m·K),电导率为30%IACS。     

纳米晶Y_2O_3∶Eu~(3 )氧化物颗粒均匀性的研究

利用草酸沉淀工艺制备了纳米晶 Y2 O3∶ Eu3 氧化物 ,并研究了溶液浓度、反应温度、沉淀方式等因素对制备纳米晶 Y2 O3∶ Eu3 氧化物粒度的影响 ,最后利用表面活性剂的空间位阻效应来控制粉末的团聚尺寸和粒径分布     

甘油体系中纳米铜粉的制备研究

本课题采用甘油还原铜盐法制备纳米铜粉。将甘油和铜盐按一定量的摩尔配比混合加热,同时加入适量的分散剂PVP,快速搅拌,控温反应一定时间,冷却至室温,产品经无水乙醇稀释后,再用无水乙醇数次洗涤、抽滤,398K真空干燥2h,得到紫色纳米铜粉。并对纳米铜粉进行了XRD、TEM表征。结果表明:所制备的纳米铜粉呈球形,铜粉粒径小于60nm,分散性较好,纯度较高。     

均匀沉淀法制备纳米氧化锌实验研究

以尿素和硝酸锌为原料,以辛基苯酚聚氧乙烯(10)醚(OP-10)为表面活性剂,采用均匀沉淀法制备了纳米氧化锌.采用单因素实验和正交实验,系统的分析了锌离子浓度、反应物配比、反应温度、煅烧温度、煅烧时间对氧化锌粒径的影响.采用扫描电镜(SEM)、X射线衍射(XRD)对所制备的纳米氧化锌进行了表征.结果表明,在锌离子浓度为0.4 mol/L,反应物配比为4,反应温度为120C,煅烧温度为450℃,煅烧时间为2h时,所得氧化锌粒径最小,且分布均匀,其平均粒径为30 nm,晶型为六方晶系.     

转炉炉壳热应力分析

根据实际转炉建立实体模型。以有限元为手段,考虑了炉衬和炉壳材料的物性参数随温度变化的特点和炉衬与炉壳之间膨胀间隙,计算了转炉炉壳在温度载荷和炉衬膨胀压力同时作用下的热应力。所得结果可为转炉炉壳设计提供依据。     

焦炭热性能指标意义浅析

通过对焦炭在高炉内的历程及其变化规律的剖析,阐述焦炭热性能指标的意义,形象地把焦炭在高炉内的损耗分为三部分(M1,M2,M3)。指出M2对焦比及焦炭价格有一定的指导作用。     

Results of treatment of cancer of the cardia

Cancer of the cardia is traditionally discussed with cardiac cancer of the lower portion of the esophagus and upper gastric cancer invading the esophagus, and the specific characteristics of cancer of the cardia have never been clearly defined. We reviewed the outcome of 172 patients with adenocarcinoma of the cardia who had undergone radical surgery between 1949 and 1994 in the Division of Gastrointestinal Surgery of the Cancer Institute Hospital. The centers of the tumors were located within 2 cm above and below the boundary between the esophagus and the stomach, and their longitudinal diameter was less than 8 cm. We divided the patients into an early period (1949-1979; n = 79) and a late period (1980-1994; n = 93), and focused on the historical transition. There were no differences in patient gender or histology between the two periods. However, the late period was associated with fewer cases of esophageal invasion and shorter longitudinal diameter, as the age of the population advanced. The number of advanced cancers such as the localized and infiltrative type had decreased, and early cancer and early clinical stage had become more common, but despite the fact that the number of early cancers had increased, extended dissection, such as thoracic and paraaortic lymph node dissection, was performed more frequently. By clinical stage, the long-term outcome markedly improved in Stage I patient in the late period, and tended to improve in Stage II and III patients. This appears to have been attributable to the prevention of micrometastasis by extended dissection, although the number of early cancers is another major potential cause. There were no differences in the outcome of Stage IV patients between the two periods, and further advances in multimodality therapy must be awaited. The range of resection is basically proximal gastrectomy, and if there are adequate indications, the prognosis is favorable. In view of the status of lymphatic flow and lymph node metastasis, and long-term results, lateroaortic lymph node dissection is important. Since the number of early cancer patients has been increasing, if intraabdominal recurrence is prevented, intrathoracic lymph node dissection will contribute greatly to the outcome of such patients.     

The effect of amount of possession of the trait of hostility on accuracy of perception of hostility in others.

Some theories of personality hold that an individual's perception of others is influenced by his own personality characteristics; more specifically, that a trait of low social value will be projected more into others, and that insight into the possession of these characteristics reduces this distortion. These 2 hypotheses were tested by having a group of college students rate each other (including themselves) on degree of friendliness or hostility. Agreement with group rating about self yielded the insight score. In general, the hypotheses were supported; the "friendly" Ss were most accurate in their perception of others, and insight was positively associated with accurate perception. From Psyc Abstracts 36:04:4HL16M. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparison of rates of infection of two methods of emergency ventricular drainage

The rates of infection of two methods of external ventricular drainage in use at Atkinson Morley's Hospital--namely, (a) percutaneous drainage with Rickham reservoirs and (b) tunnelled ventriculostomies--were compared in this retrospective review. Percutaneous drainage of CSF with Rickham reservoirs was associated with a 27% rate of infection as identified by positive microbiological cultures; tunnelled ventriculostomy catheters had a 10% infection rate. The difference in the infection rate between the two methods was statistically significant (P < 0.015). Other variables examined, including the age and sex of the patients and the reasons for ventricular drainage, were not associated with an increased rate of infection. Most infections from either method were caused by a coagulase negative staphylococcus. The average duration of ventricular drainage before identification of positive cultures was 5.7 days for Rickham reservoirs and 6.0 days for ventriculostomies.     

浅析《野草》的版画特征

鲁迅先生一生热爱美术作品,对版画中木刻兴趣尤甚.<野草>作为其"写心之作",亦呈现出一些与木刻版画一致的审美特征:一是具有木刻版画的色彩特征,多对比、多冷色,有阴郁的美感;二是具有木刻版画的力度特征,环境描写、人物刻画处处刀锋毕现,遒劲有力,有一种"力之美".     

四辊破碎机车刀架的改造

针对四辊破碎机车刀架车削中存在的几个问题,详细介绍了电动车刀架的结构和工作原理,建立主要设计参数的数学表达式,并进行适当的分析。改造后,这种电动车刀架运行平稳、可靠、方便、省力,取得了预期的效果。     

Effect of antibiotics of chemotaxis of human leukocytes

The effect of 20 different antibiotics on chemotaxis by human neutrophils was studied. Human leukocytes incubated with chloramphenicol, rifampin, sodium fusidate, and tetracyclines in vitro showed markedly depressed migration. The mechanisms by which these antibiotics affect leukotaxis are discussed.