铝酸钠溶液中微量聚乙二醇的测定

本文确立了碱性条件下测定微量聚乙二醇浓度的方法——氯化钡法。通过考察波长、碘液用量、BaCl2用量、显色时间等因素的影响，得到了最佳测定条件：波长520hm，碘液用量3．0ml，BaCl2用量1.0ml，显色时间2min；线性回归方程为A=0．2492＋0．0836C。     

分光光度法测定Fe-Si-B-Nb-Cu合金中的铌含量

应用分光光度法对Fe-Si-B-Nb-Cu合金中铌含量的测定进行了研究。对试样的预处理方法、试剂和显色剂的加入量以及显色时间与温度等条件进行了优化。在优化条件下,于650nm波长处对试样进行比色分析。实验结果表明,该方法测定结果与电感耦合等离子体发射光谱法测定结果相符,其回收率为94．O％～99．5％,测定结果的相对标...     

酚试剂分光光度法测定空气中甲醛浓度的影响因素

本文研究了酚试剂分光光度法测定空气中甲醛浓度的影响因素,试验结果表明显色剂的显色时间应在30min,显色剂的加入量为0.30ml～0.45ml,显色温度宜在25℃以上.     

一种生物素改性聚乳酸生物材料的制备与性能研究

研究试图通过本体改性,将生物素接枝到聚乙二醇接枝聚乳酸(PPLA)上,以改善聚乳酸微球在药物缓释应用中血液循环时间短和无主动靶向性的缺点.在本实验室制备的聚乙二醇接枝改性聚乳酸的基础之上,采用N-羟基琥珀酰亚胺活化酯法,将生物素接枝到PPLA上,制备生物素改性聚乳酸(BPLA),通过茚三酮显色、核磁共振(1H-NMR)...     

分光光度法测定Fe-Si-B-Nb-Cu合金中的铌含量

应用分光光度法对Fe-Si-B-Nb-Cu合金中铌含量的测定进行了研究。对试样的预处理方法、试剂和显色剂的加入量以及显色时间与温度等条件进行了优化。在优化条件下,于650nm波长处对试样进行比色分析。实验结果表明,该方法测定结果与电感耦合等离子体发射光谱法测定结果相符,其回收率为94.0%～99.5%,测定结果的相对标准偏差小于1.0%(n=11),该方法操作简便、分析成本低,能满足纳米晶合金中铌含量的测定精度。     

微波消解-纳氏试剂比色-分光光度法测定烟叶中的总氮含量

用硫酸和双氧水在微波消解系统中对烟叶进行消化,使样品中的总氮转化为硫酸铵,在碱性条件下用纳氏试剂显色,420 nm波长处用可见分光光度计对溶液进行测定。结果表明:该法方便、快速、重现性好,加标回收率在90%~115%之间,可用于大批样品的测定。     

室内空气中氨的检测方法分析比较

本文对靛酚蓝分光光度法和纳氏试剂分光光度法进行了全面的分析比较研究,考察了两种检测方法的测定范围、显色时间和环保等因素,对两种检测方法的应用有了更加全面的认识.     

刚柔嵌段共聚物聚苯基喹啉-b-聚乙二醇的合成及荧光性质

以聚乙二醇单甲醚、丁二酸酐、4-氨基苯乙酮、5-乙酰基-2-氨基二苯甲酮为原料合成了以聚苯基喹啉(PPQ)为刚性链、聚乙二醇(PEG)为柔性链的"刚棒-线团"两嵌段共聚物PPQ-b-PEG.通过IR、1HNMR对其结构进行了表征,并对PPQ3000-b-PEG2000在三氟乙酸/二氯甲烷稀溶液的荧光性质进行了初步研究.结果表明:1mg·ml-1的PPQ3000-b-PEG2000(1:1氟乙酸/二氯甲烷,v/v)在459nm作监控波长下测量的激发光谱,在430nm处有最大发射波长,相对强度为509,PPQ3000-b-PEG2000可实现可见光的激发.它的最大发射波长随溶液浓度的增大发生红移,与混合溶剂的配比无关.     

用铝试剂光度法测定纳米复合镀层中的铝

建立了用分光光度法测定纳米复合镀层中纳米粉体Al2O3共析量的方法.在pH=6.3的乙酸-乙酸铵缓冲溶液介质中,Al3 与铝试剂反应生成稳定配合物,体系的最大吸收波长为520 nm,研究了镀层的处理方法和酸度、显色剂用量、显色时间及共存离子对测定结果的影响.结果表明:铝在0～0.5 μg/mL范围内遵守比尔定律.该方法已用于复合镀层中纳米Al2O3共析量的测定,相对标准偏差为1.1%～2.4%,回收率在95.4%～98.8%之间,效果较好.     

微波消解-钼锑抗光度法测定蔬菜中总磷

采用微波消解-钼锑抗光度法测定蔬菜中的总磷,为获得最佳试验条件,对微波消解条件中的酸的种类、消解时间和消解温度等影响因素进行优化,结果表明:硝酸和过氧化氢(体积比7∶1)为最佳消解酸系,最高消解温度180℃,保持时间20 min。对紫外-可见光波长和显色时间对试验结果的影响进行探讨,结果表明710 nm和20 min为最佳试验条件。为评价该方法的可靠性,选用两种蔬菜标准物质GBW 10048和GBW 10049对该方法进行分析验证,测定值与标准值相符,相对标准偏差(RSD)分别为0.884%和0.938%,添加回收率大于89.93%,表明该方法拥有良好的准确性和精密度。微波消解-钼锑抗光度法具有简单、省时省力、试剂用量少等优点,能够满足蔬菜中总磷的测定。     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.     

Analysis of marine hydrobiont lipid extracts as possible cryoprotective agents

We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes.     

Low-Temperature Properties of Silver

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability.     

Early ironwork in Biscay: Survey,excavation, experimentation and materials characterization. An integral study of the mountainside ironworks (ferrerías de monte or “haizeolak”)

ABSTRACT

The production of iron in Biscay (Basque Country, Spain) has been a hallmark of this territory of the North of the Iberian Peninsula throughout its history. The Archaeology team of the Basque Country Mining Museum has spent 13 years, so far, studying the origins of this activity through the evidences left at the old pre-hydraulic iron production workshops known as mountainside ironworks (ferrerías de monte) or haizeolak. It has catalogued 170 archaeometallurgical sites of this type in Biscay, and the archeological excavation of some of them has led to the knowledge of the different stages of the production process that took place in these workshops. The team has also experimentally reproduced the work carried out in a mountainside ironworks from the High Middle Ages, and it has currently started the characterization process of this type of activity through the study of the collected materials.     

Mechanism Study on the Wear of CrAlTiN Coated High-Speed Steel Twist Drills Under Dry Cutting Conditions

As demands about environment protection are growing up, dry cutting technology is getting more and more concerns from all over the world. Main works performed here are study on dry cutting performances and wear mechanisms of M2high-speed steel (HSS) twist drills with CrAlTiN multicomponent coatings, which was deposited using magnetron sputter ion plating system, in drilling 45 and 30CrMnSiA steel, and their comparisons to those in drilling the same steel but using monolayer CrN and commercial TiN coated drills. Drilling performances of drills are evaluated mainly through the measurements of width on outer corner flank land and the cutting forces. Results show that performances of CrAlTiN coated drills are better than those of monolayer CrN and TiN coated drills. In drilling 45 and 30CrMnSiA steel, the average tool life of the CrAlTiN coated drills are 17.2 and 11.8 times higher than those of the uncoated drills. Observing wear of the drill with scanning electronic microscope, results show that there is no crack or spallation of the CrAlTiN coatings in wear zones. Main mechanism of the wear here is adhesion.     

Study on Bond Ability of Arc-Spraying Coatings with Different Surface Pretreatment on Cast-Iron

Arc spraying coatings are widely used in various applications, but uncommon in cast iron substrate. Different surface pretreatment technology is tested on substrates of gray cast iron. Surface roughness and residual stress were measured by TR200 and X-ray diffraction analyzer. Influence of different surface pretreatment methods ( dry blasting and fusebond) on roughness and residual stress was analyzed. The arc-sprayed coatings of wire 3Cr13 (φ2mm) on gray cast iron substrate is studied. The microstructure and interface of bonding layer were observed by SEM. The bond strength was taken by tensile test. Results show that bond strength with grit blasting is higher than fuse-bond; it is feasible to make wire 3Cr13 coating with arc spraying on cast iron substrate roughened by grit blasting.     

Structural Characteristics of TiO2 Ceramic Coating by Micro-Plasma Oxidation

TiO2 ceramic coatings with thickness of 20 μm were formed on the surface of pure titanium by micro-plasma oxidation. Their micro-structures were investigated by by using X-ray diffraction and their surface images were detected by using scan electronic microscope. There were three kinds of TiO2 coatings, pure anatase type TiO2 phase, mixed phases consisted of rutile type TiO2 phase and anatase type TiO2 phase, pure rutile type TiO2 phase. The coating surface with the pure anatase type TiO2 phase is rough, while the coating surface with the pure rutile type TiO2phase is smooth. The upper coating surface with the mixed type TiO2 phases is anatase type TiO2 structure and the subsurface of the TiO2 coating is rutile type TiO2structure.     

Evaluation of fatigue life of steel using steel grain size

The insightful discussion of the relationship between the construction of metallographic and fatigue life and proposition of mathematical relationships describing this relationship was conducted in the paper. This paper presents a method for estimating the fatigue life, based on the construction of the microstructural material taking into account the grain size and the participation of ferrite and pearlite phase.