冀东磁铁精矿球团焙烧机理的研究

研究了焙烧温度、时间等因素对冀东磁铁精矿粉球团焙烧质量的影响.当预热温度超过1 000 ℃时,颗粒表面生成液相,造成球团氧化不完全;当焙烧温度超过1 275 ℃时,球团中的脉石大量同化,产生大量硅酸盐液相,降低成品球强度.冀东磁铁精矿球团最佳焙烧工艺为:氧化温度为900～950 ℃,氧化时间不低于20 min,焙烧温度为1 250～1 275 ℃,焙烧时间不低于20 min.     

Physicomechanical properties of detonation coatings made from stainless-steel powders

A method has been developed for determining the strength and plasticity characteristics of detonation coatings; the structure and phase factors have been used along with the physicomechanical characteristics and the adhesion to optimize the production conditions. Phase transformations occur during the formation of the coatings that govern the strength, ductility, and tribotechnical properties. In spite of the structural and phase changes that accompany coating formation, layers up to 0.25 mm thick have the properties of the compact materials.Institute of Problems of Materials Science, National Academy of Sciences of the Ukraine, Kiev. Translated from Poroshkovaya Metallurgiya, Nos. 7–8, pp. 59–66, July–August, 1994.     

Structure and wear of detonation coatings made from eutectic iron-base powders

Conclusions Change of detonation spraying parameters substantially affects the structure and tribological properties of coatings made from iron-based eutectic-alloy powders containing refractory inclusion phases. This change permits the application of dense, wear-resistant coatings on low-carbon steels. The tribological properties of the friction pair, detonation eutectic coating versus U8 steel, are improved by changing the micromechanical properties of the coating structural constituents.Translated from Poroshkovaya Metallurgiya, No. 9(261), pp. 71–76, September, 1984.     

A new class of electric-spark coatings for articles made of titanium alloys for use in extreme conditions

The formation, structure, composition, and properties of electric-spark coatings on titanium alloys (VT 6, VT 20) obtained with the use of hard-alloy electrode materials (EM) on the basis of titanium carbide and boride, as well as nanodispersed tungsten carbide are considered. The peculiarities of the mass transfer of EM on VT 20 grade titanium alloy when the parameters (current strength, frequency, and duration) of the pulsed current discharge vary are investigated. The optimum power mode of the electric-spark treatment of the Ti alloy by new EMs (I = 175 A, f = 800 Hz, and = τ μs) are determined. Investigations of the structure, phase composition, and properties (such as continuity; thickness; microhardness; friction coefficient; and wear-, heat-, and fretting resistance) of formed electric-spark coatings are carried out. Their phase composition and topography are investigated after high-temperature treatment (at 600°C for 100 h). It is shown that electric-spark treatment by new hard-alloy EMs improves the properties of electric-spark coatings on VT 20 titanium alloy compared to similar coatings obtained with the use of widely spread electrodes VK8, T15K6, and relit.     

Low-temperature electrolysis of aluminum in a bath made of corundum high-alumina concrete

Low-cement high-alumina corundum concrete is tested as a lining material for the electrolysis of aluminum from the KF-AlF₃-Al₂O₃ melt at 750°C. From the results of a 100-h experiment, it was revealed that the process is stable with a rather high current efficiency. Concrete lining did not corrode during this time. The material under investigation does not significantly affect the quality of the obtained metal. Based on the results of a chemical analysis of the cathode metal before and after the experiments, the calcium and potassium content satisfies the requirements of GOST (State Standard) 11069-2001 for technically pure primary aluminum. The investigated high-alumina concrete can be suggested as a lining material in the design of an aluminum electrolyzer bath with a low-temperature potassium-containing electrolyte.     

优化配矿强化西澳超细粒磁铁精矿球团焙烧研究

进行了西澳超细粒磁铁精矿分别配加国产磁铁精矿和巴西赤铁精矿制备氧化球团矿的实验研究.结果表明,以100%西澳超细磁铁精矿为原料制备氧化球团矿时,球团预热及焙烧性能较差,在预热温度为1050℃、预热时间20 min及焙烧温度1300℃、焙烧时间40 min的条件下,预热球团和焙烧球团矿抗压强度分别为每个502和2313 N.西澳超细粒磁铁精矿配加40%国产磁铁精矿或20%巴西赤铁精矿时,球团适宜预热温度由1050℃分别降低到950和975℃,适宜的焙烧温度由1300℃分别降低到1250和1280℃;而且焙烧球团矿的抗压强度分别提高到每个2746 N和每个2630 N.焙烧球团矿的微观结构研究表明：配加国产磁铁精矿后,焙烧球团矿中Fe₂O₃晶粒发育优良,晶粒间互联程度提高,晶粒粗大,孔隙率低,固结更加紧密.配加20%巴西赤铁精矿时,焙烧球团矿中Fe₂O₃晶粒基本连接成片,Fe₂O₃晶体发育良好.优化配矿是改善西澳超细粒磁铁精矿球团矿预热及焙烧性能的有效途径.     

Preparation of Al-based amorphous coatings and their properties

Al₈₆Ni₈Co₁La₁Y₂Gd₂ amorphous coatings were prepared using cold gas kinetic spray technology.The results show that Al₈₆Ni₈Co₁La₁Y₂Gd₂ amorphous coatings are achieved with the porosity about 3.2%,thickness about 893 μm,the amount of amorphous phase about 82.5%,the hardness about 300 HV0.2.The corrosion potential and anti-corrosion life of 7075 T6 alloy aluminum are about-0.78 V and 72 h,respectively.The electrochemical analysis and neutral salt spray are about-0.69 V corrosion potential and 274 h anti-corrosion life for amorphous Al-based coatings,respectively.Therefore,the life of the Albased amorphous coatings is about 3.8 times that of 7075 T6 aluminum alloy.Besides,the failure mechanism was analyzed using TEM in this investigation.In a word,Al₈₆Ni₈Co₁La₁Y₂Gd₂ coatings keep dense structure,high amorphous content,favorable amorphous phase stabilizing ability and longer anticorrosion life.That is,Al₈₆Ni₈Co₁La₁Y₂Gd₂ coatings have better comprehensive properties.Therefore,these findings indicate that the present Al₈₆Ni₈Co₁La₁Y₂Gd₂ amorphous coatings prepared using cold gas kinetic spray technique can protect aluminum alloy very well and they can be considered to be used in aviation field.     

Contents of resveratrol, piceid, and their isomers in commercially available wines made from grapes cultivated in Japan

The presence of resveratrol (3,5,4'-trihydroxystilbene) and its beta-glucoside, piceid (resveratrol-3-beta-D-glucopyranoside), together with their isomers in wine appears to be one of the beneficial factors conferring a protective effect against cardiovascular disease through red wine ingestion. A total of 42 red and white wines was collected in areas from Hokkaido to Kyushu in Japan. The wines were fractionated with a C18 Sep-pak cartridge, and the active principles were eluted with ethyl acetate. Crude trans- and cis-piceid were extracted from a Chinese medicine, 'Kojohkon' (Polygonum cuspidatum), and their retention times and UV absorption were confirmed by HPLC. trans- and cis-Resveratrol, and trans- and cis-piceid were analyzed in a short C18 HPLC column, and cis-resveratrol was quantified from the amount of cis-isomer converted from authentic trans-resveratrol that had been treated by UV irradiation. The content of piceid is shown as the resveratrol equivalent. The average content of total stilbene compounds was 4.37 mg/liter in red wines, while only 0.68 mg/liter in white wines. Red wines made from Pinot noir, Merlot, and Zweigeltrebe grapes all had a high resveratrol content.     

The use of rotating electrodes in the electrolysis of molten zinc chloride electrolytes

In order to decrease the resistive losses in molten salt electrowinning cells, it is necessary to reduce the interelectrode spacing. Under stationary conditions, this can only be achieved at the detriment of the current efficiency. However, by rotating 100-mm-diameter electrodes, it was found for plane disc electrodes that at a current density of 10,000 A m⁻², a separation of 4 mm, and a rotation speed of 100 rpm, a current efficiency of 75.5 pct for the electrolysis of zinc from a zinc chloride, sodium chloride, potassium chloride electrolyte was achieved. This was 31 pct above that of the equivalent stationary case. The use of conical electrodes which combined centrifugal and gravitational separation increased the current efficiency to 85.7 pct at a rotation speed of 44 rpm. Increasing the scale of the electrodes to 200 mm in diameter resulted in similar efficiencies. These results and a low temperature study using perspex discs and cones in water indicated that the removal of the anode gas may be the rate-limiting step. Formerly Research Student with the Department of Materials Science and Metallurgy, University of Cambridge.     

Excipients and their use in injectable products

This article describes the role of the nurse practitioner in sexual health assessment and sexual counseling. Topics of potential sexual health concerns of primary care clients are identified. The essential components of sexual counseling consist of establishing a trusting relationship with the client, developing a systematic repertoire of questions to screen for sexual health concerns, and one-on-one counseling with the permission, limited information, specific suggestions, and intensive therapy (PLISSIT) model. References for further information on sexual education and sexual health are identified.     

Creep and oxygen diffusion in magnetite

The creep rate of polycrystalline Fe₃O₄ has been measured as a fonction of stress and oxygen partial pressure in the temperature range 480–1100°C. A regime of power law creep is found at high stress, with a stress exponent of ≈- 3.1 and an activation energy of 264 kJ/mol. A regime of diffusional flow is found at lower stresses and is interpreted as Nabarro-Herring creep. The data for the two regimes are combined to deduce an oxygen diffusion coefficient of ≈-10⁻⁵ exp(−264 kJ/mol/RT) m²s⁻¹, with oxygen vacancies suggested as the mobile species.     

In vivo evaluation of magnetite nanoparticles for use as a tumor contrast agent in MRI

Magnetite nanoparticles, coated by three different artificial polypeptides, were conjugated to an antibody specific to the carcinoembryonic antigen (CEA). To protect the particles from fast blood elimination, the coats were modified by various sugars, polyethyleneglycol, albumin, and sialoproteins, respectively. The protective effect was determined by using a specific in vitro test and by analyzing the biodistribution of the nanoparticles in nude mice grafted with CEA-tumors. In particular, a prolongation of the blood circulation time has been expected, if a natural modifier is attached to the coated nanoparticles. Although the elimination rate could hardly be decreased by any modifiers, the tumor accumulation is slightly improved by using the specific sialoprotein glycophorin B. The usefulness of nanoparticles as image contrast agents is probably limited by their microdistribution within the tumor tissue. The requirements for a contrast agent to be highly tissue specific are discussed.     

钒钛磁铁矿提钒工艺发展历程及趋势

介绍了钒钛磁铁矿提钒工艺的发展历程及工艺现状,阐述了各种提钒工艺的优点、缺点、主要工艺参数和技术指标,针对现有提钒工艺的不足,指出了下一步提钒工艺的研究方向.     

In vitro methods and their use in toxicology

Assessment of the human health risks from chemicals is based predominantly on animal studies. After quantitative evaluation of data, a no-observed adverse effect level (NOAEL) is determined. The NOAEL is subsequently extrapolated to the human situation, resulting in a recommended exposure limit for the general human population. The aim of this work is to point out to the use of alternative methods in toxicology which diminished the number of animals in standard tests of toxicity and to the use of in vitro techniques in cytotoxicity and genotoxicity of chemicals.