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A man had a quarrel with his wife. Suddenly he collapsed and became cyanotic. The woman supposed him to be dead. Because she was afraid of familiar requital, she opened the gas-cock of the cooking-range to pretend a suicide; methane emitted. The autopsy revealed a fresh cardiac infarction. Postmortem chemical analysis established methane in the blood. The question was, whether the methane had any importance for the death. By experimental inhalation of a methane-air-mixture (3%) we could expose, that the methane concentration in postmortem blood didn't have any relevance for the death. 相似文献
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Calcium Phosphate Materials Prepared from Precipitates with Various Calcium:Phosphorus Molar Ratios 总被引:3,自引:0,他引:3
Anna Alósarczyk Ewa Stobierska Zofia Paszkiewicz Marek Gawlicki 《Journal of the American Ceramic Society》1996,79(10):2539-2544
Depending on the calcium:phosphorus molar ratio of the initial precipitates determined by precipitation conditions (calcium:phosphorus molar ratio of reactants and pH of reaction environment), after sintering at 1250°C, monophase, biphase, or triphase ceramics consisting of hydroxyapatite, β-tricalcium phosphate, α-tricalcium phosphate, and calcium oxide were obtained. The phase composition and properties—i.e., density, shrinkage, hardness, bending strength, and roughness—of the fractured surfaces of the isostatically re-pressed sinters were determined. 相似文献
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This work demonstrates the applicability of the free-radical addition of ω-functional mercaptans onto 1,2-polybutadienes as a modular synthetic pathway toward a toolbox of diverse functional block copolymers. Functional groups included, for instance electrolytes (carboxylic acid and amine), l-amino acid, and fluorocarbon. The number of functional groups attached to the polymer was lower than that of double bonds reacted (degree of functionalization=50–85%, typically 70–80%) due to cyclization of two neighboring units, but the narrow molecular-weight distribution of the parent (co)polymer was always maintained. 相似文献
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Characterization of water penetration inside organic coatings by capacitance measurements 总被引:3,自引:0,他引:3
Zofia Kolek 《Progress in Organic Coatings》1997,30(4):287-292
Knowledge of the solution of transport equations allows one to determine parameters which are needed to evaluate the protective properties of organic coatings, particularly the penetration of water inside the coatings. The form of equations representing the processes of transport and their usefulness should be verified by experimental results. The mathematical aspect of the problem is studied in the framework of the theory of partial differential equations. Various methods of solving the equations, the problem of their univocal character, their regularity and properties are considered. The form of a particular solution depends on the imposed problem. The method of determination of the depth of water penetration inside the organic coatings is based upon the solutions of the transport equation. The use of Boltzmann transformation allows the concentration profiles dependent on additional parameters (e.g., temperature) to be represented. The solutions of the diffusion equation for various limiting conditions as well as the methods of determination of diffusion coefficient are presented. The method of evaluation of the depth of medium penetration inside the protective coating in the case of a non-stationary process is described. The use of Boltzmann transformation made it easier to analyse the solution of the diffusion equation. The dependence of the water diffusion coefficient in epoxide-phenol lacquer coatings on temperature was determined and the applicability of Arrhenius' law was found in the temperature range from 303 to 363 K. Knowledge of the diffusion coefficients enabled the time of water penetration inside organic coatings to be determined. 相似文献
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Aneta Zima Zofia Paszkiewicz Dominika Siek Joanna Czechowska Anna Ślósarczyk 《Ceramics International》2012,38(6):4935-4942
In order to improve some features of bone substitutes the new self-setting composite-type implant material based on Mg2+/CO32? co-substituted hydroxyapatite (Mg-CHA) and calcium sulfate hemihydrate (CSH) was developed. Synthetic hydroxyapatites doped with small amounts of additives found in natural bone (e.g. Mg2+ and CO32?) are regarded as promising components of calcium phosphate bone cements (CPCs). The CPCs, now available on the market, due to low resorption rate are too stable to permit material degradation and are slowly replaced by the newly formed bone. To improve cement resorption we used calcium sulfate which is a well-known biodegradable and biocompatible bone defect filler. Combining properties of Mg-CHA and CSH allowed developing a new, promising, easy shapeable implant material with high potential for bone regeneration. 相似文献
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Justyna Sienkiewicz-Gromiuk Liliana Mazur Agata Bartyzel Zofia Rz?czyńska 《Journal of Inorganic and Organometallic Polymers and Materials》2012,22(6):1325-1331
The reaction of sodium hydroxide with 2-aminoterephthalic acid leads to the formation of a complex of the general formula: [Na2(atpt)(H2O)5]·H2O, where atpt?=?[NH2C6H3(COO)2]2?. Sodium 2-aminoterephthalate was synthesized and characterized by single-crystal X-ray diffraction, FT-IR spectroscopy, thermal analysis and coupled TG–FT-IR technique. Crystallographic study of the sodium complex reveals that the compound crystallizes in the triclinic system, the space group P-1 with a?=?7.983(3) ?, b?=?8.405(3) ?, c?=?11.311(5) ?, α?=?70.74(3)°, β?=?76.57(3)°, γ?=?83.12(3)° and V?=?696.1(5) ?3. On heating in air atmosphere the compound in question loses all water molecules in two steps in the temperature range 30–205?°C. The anhydrous form of the complex is stable up to 370?°C and then decomposes to sodium carbonate. 相似文献
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The magnetization reversal processes of the as-quenched Sm2Gd10.5Fe8Co64Zr2.5Cu13 ribbons obtained by melt-spinning method have been investigated. From the analysis of the initial magnetization curve it was deduced that the main mechanism of magnetization reversal process is the pinning of domain walls at the grain's boundaries. From the dependence of the reversible magnetization components as a function of magnetic field it was found that reversible rotation of magnetic moment vector results in high initial values of this component. The presence of several maxima on the differential susceptibility curves derived from the irreversible magnetization component in both direction of magnetization implies existence of several pinning sites for domain walls. The interaction between the alloy grains have been examined by using the so-called δm(μ0Hi) plot. The values of δm(μ0H) for investigated alloy remains positive for an applied field up to 1.15 T and negative for higher fields. Such behavior of δm(μ0Hi) dependence certifies that the dominant interaction between grains is the short range exchange interactions but low values of δm(μ0H) implies that these interactions are week. 相似文献