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31.
R K Mandal Ch. Durga Prasad O M Parkash Devendra Kumar 《Bulletin of Materials Science》1987,9(4):255-262
Glasses with varying molar ratios of PbO/BaO in the system BaO-PbO-TiO2-B2O3-SiO2 were prepared keeping (BaO + PbO)/TiO2 ratio equal to one. The glasses were ceramized by two-stage heat treatment. X-ray diffraction indicates that PbTiO3 crystallizes in lead-rich glasses while BaTiO3 precipitates in barium-rich compositions. Solid solution (Ba, Pb)TiO3 does not seem to crystallize over the entire range of compositions. Simultaneous presence of PbO and BaO in the initial glass
composition reduces the yield of ferroelectric phase. Dielectric properties have been interpreted in terms of microstructural
features. 相似文献
32.
This paper studied the influence of steam on heavy oil catalytic pyrolysis. Experiments of Chinese Daqing atmospheric residue
catalytic pyrolysis on CEP-1 were conducted in a confined fluidized bed reactor, with steam and nitrogen being used as the
fluidizing gas, respectively. The effects of steam on the volume of contents of the components in pyrolysis gas, product yields,
and carbon dioxide formation were discussed. The results of contrast tests showed that steam not only had the action of the
fluidizing gas and the dilution gas, but also participated in steam gasification and water-gas shift reactions. In catalytic
pyrolysis processes, steam could maintain the activity of catalysts, accelerate the reactions of carbonium ions, inhibit undesired
secondary reactions, and enhance the yields and selectivity of the aimed products.
Published in Russian in Neftekhimiya, 2007, Vol. 47, No. 2, pp. 99–102.
The text was submitted by the authors in English. 相似文献
33.
34.
Micellar Two Phase-Hydroformylation of Multiple Unsaturated Fatty Substances with Water Soluble Rhodiumdicarbonyl/tert. Phosphine Catalyst Systems Low- and medium-molecular ω-unsaturated carboxylic acid methyl esters inclusive of the ω-decenoic acid ester can be hydrofomylated successfully according to the two phase method in an aqueous-organic medium using the water soluble rhodium carbonyl/tris(sodium-m-sulfonatophenyl)phosphine complex as catalyst system. Highermolecular unsaturated fatty acid esters, e.g. the triple unsaturated linolenic acid methyl ester or fatty oils like linseed oil can be hydroformylated only according to the micellar two phase technique in course of which surfactant micelles cause a solubilisation of the water insoluble unsaturated fatty substances in the aqueous catalyst phase. The different efficiences of the various types of surfactants for the micellar two phase hydroformylation was investigated and interpreted. Best suitable for the micellar two-phase hydroformylation are cationic surfactants. By means of these surfactants linolenic acid methyl ester could be hydroformylated to the triformyl derivative with a selectivity of 55%. The recovery of the catalyst solution free from losses of rhodium succeeded by simple phase separation in a technically satisfying manner. 相似文献
35.
V Chandrasekaran Ch Sreerama Murthy P Subrahmaniam G Venkateswarlu 《Bulletin of Materials Science》1986,8(1):39-48
Iron-chromium-cobalt alloys possess attractive magnetic properties combined with good formability and hence are identified as technologically important magnetic materials. Alloys with compositions Fe-28·9 Cr-15·6 Co and Fe-28·4 Cr-20·1Co (weight percent) have been studied. Heat-treatment parameters during thermomagnetic treatment viz temperature, time and external magnetic field were optimized with reference to magnetic properties. The fully treated anisotropic alloys develop remanence=11·5–12·0 kilo Gauss, coercivity=600–650 Oersted and energy product=4–4·5 million Gauss Oersted. Electron microscopic and Mössbauer spectroscopic techniques were used to identify the original and transformed phases. During the various stages of the development of the alloy, the changes in mechanical hardness were correlated with magnetic hardness. 相似文献
36.
Current efficiency losses in indirect electrochemical processing 总被引:3,自引:0,他引:3
37.
Investigation and Legal Evaluation of Polycyclic Aromatic Hydrocarbons in Vegetable Fats and Oils The analysis of 40 native and refined commercially available vegetable fats and oils reveals the influence of the environment and the treatment on the contamination with PAHs. Totally refined oils and fats have no or only a low contamination of PAHs whereas grapeseed oil contains PAHs to a high extent. This fact has to be deduced to the old-fashioned drying process of the pressed grapes. The analytical procedure with HPLC and fluorimetric detection was done after alcaline hydrolysis. The PAHs were extracted using the distribution between DMF, cyclohexane and water. The legal evaluation of high contaminated is discussed in regard of national and international regulations. 相似文献
38.
高科技纤维在摩擦制动材料中的应用 总被引:1,自引:0,他引:1
本文介绍了一些高科技纤维在聚俣物基摩擦材料中的使用情况,指出在摩擦材料中使用高科技纤维已成为摩擦材料的一个发展趋势,但需要大大提高高科技纤维的性价比和使用纤维混杂技术。 相似文献
39.
Carbon dioxide has been previously identified as a critical volatile factor that stimulates hyphal growth ofGigaspora margarita, a vesiculararbuscular mycorrhizal fungus, and we determined the optimal concentration at 2.0%. The beneficial effect of CO2 on fungal development is also visible in the presence of stimulatory (quercetin, myricetin) or inhibitory (naringenin) flavonoids. Sterile root exudates from carrot seedlings stimulate the hyphal development ofG. margarita in the presence of optimal CO2 enrichment. Three flavonols (quercetin, kaempferol, rutin or quercetin 3-rutinoside) and two flavones (apigenin, luteolin) were identified in carrot root exudates by means of HPLC retention time. Flavonols like quercetin and kaempferol are known to have stimulatory effects on hyphal growth ofG. margarita. 相似文献
40.
The reduction of NO by propene in the presence of excess oxygen over mechanical mixtures of Au/Al2O3 with a bulk oxide has been investigated. The oxides studied were: Co3O4, Mn2O3, Cr2O3, CuO, Fe2O3, NiO, CeO2, SnO2, ZnO and V2O5. Under lean C3H6-SCR conditions, these oxides (with the exception of SnO2) convert selectively NO to NO2. When mechanically mixed with Au/Al2O3, the Mn2O3 and Co3O4 oxides and, to a much greater extent, CeO2 act synergistically with this catalyst greatly enhancing its SCR performance. It was found that their synergistic action is not straightforwardly related to their activity for NO oxidation to NO2. The exhibited catalytic synergy may be due to the operation of either remote control or a bifunctional mechanism. In the later case, the key intermediate must be a short-lived compound and not the NO2 molecule in gas-phase. 相似文献