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141.
The effect of microstructure on the mechanical properties of two-phase titanium alloys 总被引:1,自引:0,他引:1
This article presents the results of investigations of microstructure and mechanical properties of two-phase +β titanium alloys with different volume fraction of the β-phase. Microstructure of the specimens was examined using an optical microscope. Fracture surfaces were observed by SEM technique. The influence of the microstructure and phase composition on the mechanical properties of the alloys was studied. Static tensile tests, hardness tests and fatigue investigations were performed. It was noticed that the volume fraction and chemical composition of the β-phase has a significant effect on mechanical properties and cracking process during fatigue. 相似文献
142.
Ryszard Zieliński 《Journal of surfactants and detergents》2020,23(6):1087-1098
In this work, we report results of our investigation on the relationship between the Krafft temperature of ionic surfactants in aqueous solutions and their chemical structure. We tested empirical values of the Krafft temperature available in literature for aqueous solutions of 234 ionic surfactants and correlated them to the surfactant chemical structure. In this work, we propose a novel set of 67 group contributions for calculation of the Krafft temperature of ionic surfactants in aqueous solutions. Using them, the Krafft temperature values in aqueous solutions for 174 anionic, 43 cationic, and 17 zwitterionic surfactants were calculated and the estimated values obtained in this way were compared with experimental values. We have demonstrated that the newly developed set of numerical values structural group contributions of the surfactants allows correct estimation of the Krafft temperature value for the tested set of data with the maximum error 7.6°C and the mean square error 3.7°C for various types of ionic surfactants in aqueous solutions. 相似文献
143.
Hasnaa Jorio Ryszard Brzezinski Michle Heitz 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2005,80(7):796-804
A novel procedure for the study of the biodegradation kinetics of styrene is proposed in this paper. Microbial growth tests in the presence of styrene were performed using suspensions of microorganisms prepared from samples of filter bed material. This material had been directly withdrawn previously from an operating biofilter employed for the removal of styrene vapours from air. The kinetics tests were initiated immediately after transfer of filter bed samples from the active styrene filter bed to sealed flasks containing a mineral‐based medium, and were performed in such a manner that no enrichment technique or lag phase treatment was necessary to activate the desired biodegradation of styrene. The complete biodegradation of freshly introduced styrene was observed within a few hours of the filter bed's initial contact with the active microbial suspension. A novel theoretical development, as proposed in this study, has provided us with the means for estimating the yield coefficient of the biomass with respect to the styrene consumed and the kinetic coefficients of the growth rate without having to perform any analyses of the liquid phase after start‐up of the growth tests. Only monitoring of the styrene and carbon dioxide concentrations in the liquid and gas phases in the test flasks was necessary. The Haldane model, with inhibition expected at high styrene concentrations, was found to be the best to represent the biodegradation kinetics of styrene in this environment. Copyright © 2005 Society of Chemical Industry 相似文献
144.
145.
New metallophthalocyanines (Me---Pc) in the crystalline form were synthesized by the direct reaction between the 1,2-dicyanobenzene and filings of the metallic elements or intermetallic alloys. The reaction took place at about 480 K in vacuum over a few days. Some remarks on the reaction mechanism of the Me---Pc formation are made. It is assumed that under the experimental conditions used the 1,2-dicyanobenzene liquid undergoes a catalytic tetramerization. The catalytic atom of the metal is simultaneously coordinated by the forming tetramer. 相似文献
146.
The pH influence on photocatalytic decomposition of organic dyes over A11 and P25 titanium dioxide 总被引:5,自引:0,他引:5
Beata Zieli
ska Joanna Grzechulska Ryszard J. Kale
czuk Antoni W. Morawski 《Applied catalysis. B, Environmental》2003,45(4):293-300
The photocatalytic removal (decomposition+adsorption) of four azodyes (Reactive Red 198, Acid Black 1, Acid Blue 7 and Direct Green 99) in water was investigated using Tytanpol A11 (“Police” Chemical Factory, Poland) and Degussa P25 (“Degussa”, Germany) as photocatalysts. The effect of pH of the reaction solution has been examined. The degree of the dye removal in the solution was measured by UV-Vis spectroscopy. Photodecomposition of dye on photocatalyst surface was monitored by FTIR spectroscopy. A11 photocatalyst has lower activity in the reaction of photocatalytic decomposition of organic dyes than Degussa P25. The photocatalytic decomposition of the dyes takes place on the photocatalyst surface at pH=2 while at pH=12 photocatalytic reaction proceeds via photogenerated hydroxyl radicals for both A11 and P25. 相似文献
147.
Nowak P Labus L Stabryla J Durczok A Brus R Nowicka J Shani J 《Receptors & channels》2003,9(5):339-342
The purpose of this study was to investigate how ethanol pretreatment and storage temperatures of brain striatum affect levels of biogenic amines in this tissue. Adult Wistar male rats were injected with 25% ethanol (5.0 g/kg i.p.) while the control rats were administered i.p. with the same volume of saline. Two hours later the rats were decapitated, their brains removed, and the striatum separated. Each striatum was divided into three parts: one part was immediately frozen on dry ice and kept at -70 degrees C; a second fragment was kept in a household refrigerator (+4 degrees C); and the third fragment was kept at +22 degrees C. Twenty-four hours later, levels of DA, DOPAC, HVA, 3-MT, 5-HT, and 5-HIAA in the striatum were assayed by HPLC/ED. Immediately after decapitation; ethanol levels were assayed in the serum of ethanol-pretreated and saline-pretreated rats using gas chromatography. Our results indicate that levels of striatal DA, DOPAC, and HVA in saline-pretreated rats decreased significantly when the storage temperature of the striatum was raised from -70 degrees C, through +4 degrees C, to +22 degrees C, while levels of striatal 5-HT and 5-HIAA remained constant within the temperature range tested and levels of 3-MT fluctuated. In ethanol-pretreated rats, striatal levels of DOPAC, HVA, and 5-HIAA were increased in all three storage temperatures, while levels of DA, 5-HT, and 3-MT were decreased in those temperatures. Those decreases were most profound in striatal samples kept at +22 degrees C. We conclude that concern about possible interactions between drugs and biogenic amines should be exercised. 相似文献
148.
Gabrys J Konecki J Shani J Durczok A Bielaczyc G Kosteczko A Szewczyk H Brus R 《Receptors & channels》2003,9(5):301-307
Levels of 19 proteinous amino acids and of total free amino acids were assayed by gas-liquid chromatography in cytosols of rat atrial and ventricular heart muscle cardiomyocytes. These amino acids were assayed after the rats had been exposed to either exercise (swimming) or hypoxia (hypobaric pressure of 686 hectoPascals). Out of the total free amino acids levels of arginine, glutamine and cysteine in atrial and ventricular cardiac muscle cytosols of control rats were the highest of all amino acids assayed. The control levels of all other amino acids assayed in atrial or ventricular cardiac muscles ranged from 0.1% to 10.6% of the total free amino acids in the control rats. Physical stress (exercise and hypoxia) significantly reduced the total amount of cytosolic free amino acids in both heart muscles. While hypoxia decreased the levels of arginine in both heart muscles, exercise abolished the level of cysteine in the atrial heart muscle. Decrease in arginine levels, and elimination of cysteine from the heart's atrial muscle after physical stress, may be attributed to its utilization of nitric oxide and to its synthesis of atriopeptin and/or endothelin during stress. No change was recorded in either experimental group in the level of glutamine in heart muscle cytosol. Exercise and hypoxia affect, in different modes, the levels of all other amino acids assayed, except for tryptophan, tyrosine, and histidine, which are precursors of endogenous neurotransmitters. The impact of proteinous amino acids on some bodily functions is discussed. 相似文献
149.
The aim of the studies was to determine the effect of different methods of heat treatment on carotenoids changes and their interactions with insoluble and soluble dietary fiber. Three industrial varieties of carrot--Simba, Caropak and Fayette constituted the experimental material. Carrot cubes were subjected to heat treatment by putting in water with or without citric acid, or in a convection-type steam furnace. The total content of alpha- and beta-carotene was determined in all kinds of pureed carrots. Its amount bounded with insoluble dietary fiber and pectins was also determined. Changes in soluble and insoluble fractions of dietary fiber during hydrothermal treatment were also determined. It was found that the content of trans alpha- and beta-carotene in carrots decreased significantly (p < 0.05) after heat treatment, compared with the control sample. The loss observed during heat treatment in water was higher (up to 50%) than in the case of a convection-type steam furnace. The highest decrease in the content of insoluble fraction of dietary fiber and the highest increase in soluble fraction were observed after treatment with the use of steam. An analysis of interactions between carotenoids and dietary fiber fractions after hydrothermal processing shows their stronger affinity to forming bonds with pectins than with insoluble fiber. It was also found that the effect of heat treatment parameters was significant--the highest (by six times) increase in the content of beta-carotene bounded with pectins was noted in pureed carrots processed in a convection-type steam furnace. 相似文献
150.
Beschreibung von Laboratoriumsversuchen zur Reduktion flüssiger Schlacken des Systems CaO–MgO–SiO2–Al2O3 mit Gehalten von 28,5 bis 38,5% SiO2 im Graphittiegel in Gegenwart von kohlenstoffgesättigtem Eisen bei 1600 °C. Ermittlung der Gleichgewichtsverteilungskonstante des Siliciums zwischen kohlenstoffgesättigten Eisenschmelzen und kieselsäurehaltigen Schlacken bei unbewegter Schmelze. Aussagen über die Aktivität der Kieselsäure in der Schlacke des Systems CaO–MgO–SiO2–Al2O3. 相似文献