脉冲红外法测定紫铜中氧

一、前言铜具有很好的导热性、导电性、延展性和耐腐蚀性,是人类历史上最早使用的金属。它在工业上和国防上用途之广在金属中仅次于铁,在有色金属中占有首要的位置。     

脉冲-红外法测定紫铜中氧

随着国防工业、电子、电气工业及新技术的飞跃发展,对铜及其合金质量,特别是对其中气体杂质含量的要求也越来越高,铜中氧含量直接影响产品的导电、机械、焊接性能及使用寿命,尤其是在超真空技术方面,严格要求较低的氧含量,因此如何快速、准确测定铜中氧含量已成为当今气体分析工作者的一项重要的研究课题。     

IRO-I氧测定仪

ＩＲＯ－Ｉ氧测定仪刁伟涛，毛向华，张孟义，杜学强（钢铁研究总院，北京，１０００８１）脉冲－红外氧测定仪是目前测定金属＊和合金中氧含量的通用仪器，国外七十年代＊已有第一代商品仪器，八十年代初出现第二＊代配带微机的商品仪器［１］；国内许多科研和生产部门也...     

脉冲红外法测定纳米材料中总氧和氧分量

应用脉冲红外法测定纳米材料中氧是基于碳还原原理。总氧一步提取,氧分量则通过温度缓升程序分离测定。总氧测定与氢还原-卡尔菲休法比较,两者结果一致。对铁镍合金超细粉分析发现随着镍的加入,氧特性越来越接近纯镍。追踪铁钐纳米晶制粉过程,球磨时间越长吸入氧越多。暴露试验表明:硅氮碳纳米粉吸氧快,而纯铝纳米粉中氧保持稳定。     

脉冲红外法测定碳素铬铁焙烧料中氧

阐述了应用IRO-Ⅱ氧测定仪对碳素铬铁焙烧料中氧含量进行测定的方法.该方法准确、简便、迅速,用于碳素铬铁焙烧料中氧含量的测定,获得了满意结果.     

脉冲加热红外吸收法测定雾化铜粉中氧

采用低功率脉冲加热预处理雾化铜粉 ,选择合适的仪器条件处理单个氧峰的方式 ,应用红外吸收法测定雾化铜粉中氧 ,方法简单、快速、准确。氧的回收率为 96.1%～ 99.6% ,相对标准偏差 (RSD)小于 1.3 5 %。     

脉冲熔融-红外吸收光谱法测定铁合金粉末中的氧

铁合金主要用于钢铁冶炼,根据炼钢需要,按合金元素含量或含碳高低规定许多等级,并严格限定氧等杂质的含量。通过采用脉冲熔融-红外吸收光谱法,利用氧分析仪,考察了不同的铁合金中氧的释放情况,并通过对助熔剂、分析功率等分析条件的优化,实现了对不同铁合金中氧元素含量的快速测定,分析稳定性良好,结果标准偏差分别为RSD=2.24%(n=7),RSD=1.62%(n=7),能很好的满足生产需要。     

脉冲红外法测定金属和陶瓷粉末表面氧的研究

应用新型脉冲红外定氧仪进行金属和陶瓷粉末试样总氧和表面氧同时测定的研究,对影响分析结果的主要因素以及不同类型表面氧的确定方法进行了探讨。跟踪式升温分离提取表面氧比旧式分段升温提取法更快速准确、对各种表面氧均可达到良好的分离效果。     

脉冲熔融-红外吸收法测定镧铈合金中氧

为满足国内稀土钢研制的需要,与镧、铈及镧铈合金提纯研究同步,逐步建立脉冲熔融-红外吸收法对镧铈合金中杂质氧的测定方法。考察了称样量、分析功率、不同(助熔)浴料对分析结果的影响。找出熔体平滑、峰形好的最佳分析功率4 200W,称样范围为0.10～0.20g。从助熔剂法和浴料法中筛选并确定Cu-Sn-Fe-Ni四元浴,自制配方比例为3∶3∶1∶1(质量比);尝试\"样品与标样间隔投样校正法\"定量评估和抵消仪器(被污染)产生的干扰。实测范例显示:目前国内镧铈合金样品中氧质量分数可低至0.00679%;相对标准偏差(RSD,n=7)为5.5%。以钢中氧标准样品GBW(E)020143进行加标回收试验,回收率为101%～105%;另通过与辉光放电质谱法方法对比,一致性较好。     

过氧化氢-草酸预处理脉冲红外法测定轮轴钢中痕量氧

研究了脉冲红外法测定钢中痕量氧的试样前处理条件和仪器分析条件。当光洁度为Ra3.2μm以上,直径为4~5 mm,长度为5~7 mm的圆棒试样用乙醚清洗后,再用过氧化氢-草酸溶液浸泡清洗,水冲洗干净,置于丙酮中再清洗两次,可有效去除表面氧化膜,测得试样中氧含量的值比未经过氧化氢-草酸溶液清洗的要低,与用麂皮抛光表面方法的测定值相当。在优化的仪器分析条件下,用本法成功地测定了轮轴钢中痕量氧,相对标准偏差为3.5%~11.2%,标样的测定值与认定值相符。     

氧枪喷头使用的若干问题

氧气炼钢的优点是冶炼速度快、质量好、产量高、能耗少。氧枪是氧气炼钢时供应氧气射流的主要部件。而氧枪喷头又直接控制着氧气射流的气动力学特性,直接影响着炼钢生产。现今钢水二次精炼技术被广泛应用,但炼钢炉仍是提供纯净钢水的重要前工序,所以研究氧枪喷头还不失其重要意义。氧枪喷头的良好性能不仅取决于设计和制造质量,也取决于     

Population-specific screening by mutation analysis for diseases frequent in Ashkenazi Jews

Three-dimensional (3D) imaging of intracellular rhodamine 123 fluorescence distribution was performed by means of confocal laser scanning microscopy (CLSM). Human IGR melanoma cells grown in monolayer or multicellular spheroid culture were studied for elucidating mitochondrial membrane potential characteristics, and cell and nucleus volume dimensions. Microspheres 6 microns in diameter loaded with rhodamine B were used to calibrate our instruments for performing 3D imaging of optical sections as obtained by CLSM. Accurate optical slicing is only possible taking into consideration the physical characteristics of the objectives used like chromatic and spherical aberrations, depth discrimination or cover slip correction and the temperature dependence of the immersion medium. While 3D imaging of optical slices can be carried out showing the original shape of the object being tested without physical distortion, 3D images of microspheres show well-reproducible structures of rhodamine B fluorescence. These can be explained by a superposition of two effects, namely scattering of the fluorescence light and a gradient of the electromagnetic field strength of the laser beam due to the shape of the object. 3D imaging of optical slices of IGR cells in monolayer or multicellular spheroid culture, which have been loaded with rhodamine 123, show the location of the dye predominantly within the cytoplasm of the cells with a remarkable heterogeneity of fluorescence intensity within and between single cells, indicating differences in the mitochondrial membrane potential and thus in the metabolic activity. Due to the heterogeneity of the cell shape the cell nucleus occupies between 4 and 14% of the total cell volume. These data reveal calibrated 3D imaging as a valuable noninvasive tool to visualize the heterogeneity of cell parameters under different cell culture conditions.     

The plant Golgi apparatus

The plant Golgi apparatus has an important role in protein glycosylation and sorting, but is also a major biosynthetic organelle that synthesises large quantities of cell wall polysaccharides. This is reflected in the organisation of the Golgi apparatus as numerous individual stacks of cisternae that are dispersed through the cell. Each stack is polarised: the shape of the cisternae and the staining of the membranes change in a cis to trans direction, and the cisternae on the trans side contain more polysaccharides. Numerous glycosyltransferases are required for the synthesis of the complex cell wall polysaccharides. Microscopy and biochemical fractionation studies suggest that these enzymes are compartmentalised within the stack. Although there is no obvious cis Golgi network, the trans-most cisterna or trans Golgi network often buds clathrin-coated and sometimes smooth dense vesicles as well. Here, vacuolar proteins are sorted from the secreted proteins and polysaccharides. This review highlights unique aspects of the organisation and function of the plant Golgi apparatus. Fundamentally similar processes probably underlie Golgi organisation in all organisms, and consideration of the plant Golgi specialisations can therefore be generally informative, as well as being of central importance to plant cell biology.     

The plant translational apparatus

Protein synthesis in both eukaryotic and prokaryotic cells is a complex process requiring a large number of macromolecules: initiation factors, elongation factors, termination factors, ribosomes, mRNA, amino-acylsynthetases and tRNAs. This review focuses on our current knowledge of protein synthesis in higher plants.     

Cell-free analysis of Golgi apparatus membrane traffic in rat liver

Cell-free systems for the analysis of Golgi apparatus membrane traffic rely either on highly purified cell fractions or analysis by specific trafficking markers or both. Our work has employed a cell-free transfer system from rat liver based on purified fractions. Transfer of any constituent present in the donor fraction that can be labeled (protein, phospholipid, neutral lipid, sterol, or glycoconjugate) may be investigated in a manner not requiring a processing assay. Transition vesicles were purified and Golgi apparatus cisternae were subfractionated by means of preparative free-flow electrophoresis. Using these transition vesicles and Golgi apparatus subfractions, transfer between transitional endoplasmic reticulum and cis Golgi apparatus was investigated and the process subdivided into vesicle formation and vesicle fusion steps. In liver, vesicle formation exhibited both ATP-independent and ATP-dependent components whereas vesicle fusion was ATP-independent. The ATP-dependent component of transfer was donor and acceptor specific and appeared to be largely unidirectional, i.e., ATP-dependent retrograde (cis Golgi apparatus to transitional endoplasmic reticulum) traffic was not observed. ATP-dependent transfer in the liver system and coatomer-driven ATP-independent transfer in more refined yeast and cultured cell systems are compared and discussed in regard to the liver system. A model mechanism developed for ATP-dependent budding is proposed where a retinol-stimulated and brefeldin A-inhibited NADH protein disulfide oxidoreductase (NADH oxidase) with protein disulfide-thiol interchange activity and an ATP-requiring protein capable of driving physical membrane displacement are involved. It has been suggested that this mechanism drives both the cell enlargement and the vesicle budding that may be associated with the dynamic flow of membranes along the endoplasmic reticulum-vesicle-Golgi apparatus-plasma membrane pathway.     

燃气伴随射流在凝聚射流氧枪工作中的性状分析

讨论了凝聚射流氧枪的燃气伴随流的流动状态及燃烧特性.     

电动机频繁烧毁的原因分析及改进措施

针对某钢管厂吊车用起升电动机屡次烧毁的实际案例进行分析,列出若干可能的故障原因。根据吊车所配电动机为断续周期制工作方式,分析找出电动机烧毁的根本原因——实际负载暂载率大于吊车配套电动机暂载率。通过可行性研究,给出问题的最佳解决方案。该方案自投入运行以来,未发生过电动机烧毁事故,大大节约了工厂设备维护成本,保障了生产安全,提高了生产效率。最后,结合此案例提出了若干切合实际的设备选购及使用建议,以避免由于设备型号或参数问题而引发的各类事故,供同行参考和借鉴。