水热法制备三维花状WO_3基甲醛气敏材料

本文采用水热法成功制备了纳米花状WO_3,用于在低温工作环境下甲醛气体的高效检测。利用X射线衍射仪(XRD)和场发射扫描电子显微镜(SEM)对产物的晶体结构及微观形貌进行表征。XRD分析表明,前驱体为单斜晶系结构WO_3和正交晶系结构WO_3·0.33H_2O混合晶相,通过在450℃煅烧2h得到了单斜晶系结构WO_3。气敏测试结果表明,煅烧后的WO_3制成的气敏元件对100ppm甲醛的响应/恢复时间为5s/15s,响应值是R_a/R_g=16.5,最佳工作温度为300℃。对气敏元件表面可能发生的氧化还原反应的机理也进行了研究和讨论,认为WO_3是一种很有前景的有机污染物气敏传感材料。     

酒石酸辅助水热合成纳米MoO_2及其优异的乙醇气敏特性研究

以钼酸铵为原料,利用酒石酸辅助水热法一步合成了球状纳米结构的MoO_2,利用XRD和TEM对样品的结构、微观形貌进行分析。将样品制成旁热式气敏元件,并对其气敏特性进行了测试。研究结果表明,酒石酸在水热合成过程中对产物的形貌和相行为起决定性的作用,而且对气敏材料的气敏性影响显著。取适量的酒石酸,可有效提高传感器的灵敏度。在260℃工作温度下,MoO_2纳米球气敏元件对10×10~(-6)乙醇气体的灵敏度达3.9,并具有良好的选择性。     

CuO纳米线的简单热氧化制备及其气敏特性

传统金属氧化物气敏材料因其灵敏度低、选择性差、工作温度高等缺点已很难满足高性能气敏元件的要求,而纳米气敏材料具有高的比表面积,可显著改善材料的气敏特性.文中采用简单的电热板在330~430 ℃、空气气氛下、一步法成功制备出了具有良好单斜晶体结构的CuO纳米线,平均直径为20~30 nm,长度可达1~5 μm;CuO纳米线气敏元件在100×10-6乙醇气氛中的最佳工作温度约为260 ℃,其灵敏度分别为1.36和1.64,恢复和响应时间均小于5 s.      

退火温度对SmFeO3微结构、电性能与乙醇气敏的影响

采用溶胶-凝胶法合成了SmFeO3前驱体,并在不同温度条件下退火制备了具有单一正交钙钛矿结构的系列纳米粉体材料,利用该粉体做成了气敏元件,研究了退火温度对SmFeO3晶体结构、微结构、电性能及酒敏特性的影响,结果表明,随退火温度的增高,SmFeO3的晶胞体积减小,平均晶粒尺寸变大,元件的电导也随之增大.随退火温度从600℃增加到850℃,SmFeO3元件的最佳工作温度和气敏灵敏度增高,同时对应的气敏响应-恢复时间也变短;若退火温度进一步增高到950℃,气敏灵敏度和最佳工作温度出现下降趋势,同时对应的气敏响应-恢复时间变长.850℃退火的样品显示出最高的气敏灵敏度,对300×10-6乙醇的最大灵敏度高达51.03,气敏的响应-恢复时间短且选择性高.同时对SmFeO3元件的电导、气敏灵敏度、最佳工作温度随材料退火温度的变化规律给予了解释.     

Cd掺杂In_2O_3多孔纳米球的制备及其甲醛气敏性能

采用水热和煅烧工艺制备具有良好分散性的多孔纳米球形Cd掺杂In_2O_3颗粒,并对其甲醛气敏性能进行测试。结果表明:Cd掺杂量较低时得到的粉末为纯立方In_2O_3相,当Cd掺杂量高于4.1%(原子分数)时,除存在立方In_2O_3相外,还存在微量立方Cd O相。Cd掺杂可极大提高In_2O_3多孔纳米球的甲醛气敏性能并且降低其最佳工作温度,4.1%Cd-In_2O_3最佳工作温度为60℃,远低于纯In_2O_3的最佳工作温度120℃,能显著降低In_2O_3传感器的能耗。且4.1%Cd-In_2O_3在60℃下对50×10~(-6)甲醛的灵敏度高达1 074,远高于纯In_2O_3在120℃下的最高灵敏度57。4.1%Cd-In_2O_3在60℃对50×10~(-6)甲醛的响应和恢复时间分别为326 s和912 s;Cd掺杂In_2O_3还可明显提高其气敏选择性能。     

Sb掺杂金红石型TiO_2微球水热合成与气敏性能研究

采用水热法制备了不同Sb掺杂量的TiO_2微球,并用XRD和FE-SEM对样品进行表征。XRD结果表明,未掺杂和Sb掺杂样品均为纯金红石相;FE-SEM表明纯TiO_2微球和Sb掺杂TiO_2微球分别以纳米颗粒、纳米棒为组成单元。气敏测试结果表明,Sb掺杂使金红石TiO_2气敏元件的最佳工作温度由掺杂前的350℃降低至掺杂后的200℃,其中Sb掺杂量为7.5%的TiO_2气敏元件的灵敏度最高,在200℃下对100×10-6C2H5OH的灵敏度为11.82,响应时间为28 s,恢复时间为6 s,检测下限可达到10×10-6。     

热氧化法制备α-Fe_2O_3纳米线的气敏特性及其机理

家用燃气事故、汽车尾气和工业废气等问题日趋严重,传统气敏材料已很难满足对气体监测越来越高的要求,纳米结构α-Fe2O3因其热稳定性好、选择性好,以及无毒、抗腐蚀性强、环境友好、价格低廉等已成为最重要的气敏材料之一.采用简单的热氧化法成功制备了α-Fe2O3纳米线.纳米线平均直径为20~50 nm,长度可达1~5μm;以制备的α-Fe2O3纳米线为探测材料的气敏元件在50×10-6乙醇气氛中的最佳工作温度为383°C,灵敏度可达2.4,响应和恢复时间分别为13 s和6 s.基于α-Fe2O3纳米线制备的气敏元件在乙醇中的气敏机理为表面电阻控制型.     

水热法制备稀土元素复合氧化锌及其气敏性能

采用水热法制备了ZnO粉末和复合不同稀土离子的ZnO粉末,并通过X射线衍射谱(XRD)和扫描电镜(SEM)进行了结构和形貌表征,结果显示,ZnO材料具有六方纤锌矿的结构,稀土离子以氧化物的形式析出,纯ZnO及稀土复合的ZnO均为棒状。由气敏测试结果可看出,Sm离子的复合使纯氧化锌对甲醛、乙醇和三甲胺的灵敏度得到明显提高。Sm2O3-ZnO复合材料对1.0×10-4(体积分数,下同)的甲醛的灵敏度达到58.04,对1.0×10-3的甲醛的灵敏度达到959.60。在7种气体的干扰下,Sm2O3-ZnO复合材料显示了良好的选择性。该材料对甲醛的灵敏度是对丙酮、甲醇和乙醇的灵敏度的4倍左右。另外,Sm2O3-ZnO复合材料在300℃对1.0×10-4甲醛的响应时间和恢复时间分别为17 s和12 s。     

水热法制备不同形貌TiO_2微球及其气敏性能

采用水热法制备具有不同形貌组成单元的TiO2微球,并用XRD和FE-SEM对样品进行表征。XRD结果表明,以纳米颗粒为组成单元的样品为纯金红石相,而以纳米棒为组成单元的样品为金红石和板钛矿的混合物相;FE-SEM表明微球分别以纳米棒、纳米颗粒为组成单元。气敏测试结果表明,以纳米颗粒为组成单元的TiO2气敏元件具有最高的灵敏度,该元件在350℃下对100×10-6乙醇的灵敏度可达72.5,其响应时间为28 s,恢复时间为19 s,检测下限可达到10×10-6。     

热氧化法制备α-Fe2O3纳米线的气敏特性及其机理

家用燃气事故、汽车尾气和工业废气等问题日趋严重,传统气敏材料已很难满足对气体监测越来越高的要求,纳米结构α-Fe₂O₃因其热稳定性好、选择性好,以及无毒、抗腐蚀性强、环境友好、价格低廉等已成为最重要的气敏材料之一.采用简单的热氧化法成功制备了α-Fe₂O₃纳米线.纳米线平均直径为20~50 nm,长度可达1~5 μm;以制备的α-Fe₂O₃纳米线为探测材料的气敏元件在50×10-6乙醇气氛中的最佳工作温度为383 °C,灵敏度可达2.4,响应和恢复时间分别为13 s和6 s.基于α-Fe₂O₃纳米线制备的气敏元件在乙醇中的气敏机理为表面电阻控制型.      

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)     

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.     

Quality of life of relatives of mental patients

Usage of quality of life of psychiatric patients' relatives as the parameter of estimation of the quality of psychiatric care is considered. By means of standard questionnaire elaborated by the authors as well as by means of both individual and group conversations the quality of life was analyzed in 40 relatives which lived together with psychiatric patients. Different spheres of their life and difficulties (financial, social-psychologic, production) were examined in families with such patients. The defects of psychiatric care that had direct influence on the quality of life of the psychiatric patients' relatives are outlined.