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71.
The short-time hot-corrosion behavior of six industrial nickel-base superalloys was investigated with static deposits of Na2SO4 or NaCl or both in still air. The oxidation kinetics and scale morphologies were measured with traditional laboratory techniques-thermobalance, metallography, electron microprobe, and x-ray analyses. Susceptibility to hot corrosion was found to be correlated to the type of scale produced during simple oxidation. Alloys forming an A12O3 scale were found to be susceptible to Na2SO4 deposits, independent of their chromium content. The quantity of Na2SO4 deposit dictated the nature of the attack and, under certain conditions, the refractory element alloy additions appeared to play an essential role. Alloys containing Cr2O3 or TiO2 in the simple oxidation scale proved to be sensitive to NaCl attack. Again, the severity of the attack within the susceptible alloy group was not related to the chromium or titanium content. Although less intensive than the Na2SO4 -induced hot corrosion, NaCl contaminations provoked extensive spalling. All of the hotcorrosion types encountered in this study were interpreted in the light of existing theories.Supported by the Délégation Générale à la Recherche Scientifique et Technique. 相似文献
72.
David A. Dillard Jeffrey A. Hinkley W. Steven Johnson Terry L. St. Clair 《The Journal of Adhesion》2013,89(1-2):51-67
Some currently-available formulations of LaRC?-TPI, a thermoplastic polyimide originally developed at NASA-Langley, were found to be highly susceptible to environmental stress cracking when exposed to solvents such as acetone, toluene, diglyme and methyl ethyl ketone. The combination of stress and solvent led to rapid cracking in films and adhesive layers of this material system. Residual cool-down stresses induced when the LaRC-TPI is used as an adhesive or coating led, in the presence of a solvent, to dense “mud crack” patterns which relieve a portion of the stored energy. Because these through-the-thickness cracks are not able to relieve the stored energy in the vicinity of the adherends, additional fractures in the form of curious spiral tunnel cracks initiated and grew inward within each adhesive fragment. Micrographs of the spiral fractures are given, along with a qualitative explanation for the failure process as observed in adhesives and coatings. 相似文献
73.
M. Monev L. Mirkova I. Krastev Hr. Tsvetkova St. Rashkov W. Richtering 《Journal of Applied Electrochemistry》1998,28(10):1107-1112
Hydrogen evolution during zinc electrodeposition on a steel substrate from zincate electrolytes containing different additives was studied using various experimental techniques.The hydrogen evolution reaction is limited by the electron transfer step. Hydrogen evolution is most intensive during the first seconds from the beginning of electrodeposition due to the lower overpotential of hydrogen on steel as compared with that on zinc. The evolved hydrogen is dissipated in three ways. Most is dissipated to the atmosphere via gas bubbles at a constant rate. Some is dispersed in the electrolyte some diffuses into the steel substrate, predominantly at the commencement of deposition. The additives affect both the total amount of evolved hydrogen and its distribution. The highest amount of hydrogen is evolved in the presence of the anisaldehyde bisulphite containing composite additive. The highest amount of hydrogen included in the substrate and remaining in the electrolyte corresponds to the use of the Na–N-benzylnicotinate containing additive. In this case blistering is observed. 相似文献
74.
Christiane Stüber 《Ethik in der Medizin》2005,17(1):57-60
Ohne Zusammenfassung 相似文献
75.
The paper is focused on identifying error sources in computational fluid dynamics(CFD) predictions of a spray drying process. Seven groups of drying and atomisation parameters were selected for analysis and 13 simulation trials were performed. The theoretical results were compared with experimental data and sensitivity of the simulation results to the analysed factors was determined. The following parameters affecting the accuracy of CFD spray modelling were found: gas turbulence model, particle dispersion, atomising air, initial parameters of atomisation and heat losses to the environment. A major difference in the errors committed during modelling of spray drying process for fine and coarse sprays was observed. 相似文献
76.
Perla Relkin Amel Ait-Taleb Stéphanie Sourdet Pierre-Yves Fosseux 《Journal of the American Oil Chemists' Society》2003,80(8):741-746
The thermal behavior of hydrogenated palm kernel oil-in-water emulsions, which differed in their milk-protein composition,
was studied in parallel with other characteristic parameters such as the aggregation/coalescence of fat droplets, and the
proportion of adsorbed proteins at the oil/water interface. DSC was applied to monitor the crystallization and melting behavior
of nonemulsified and emulsified fat samples. Comparison between nonemulsified and emulsified fat samples showed that in emulsified
samples the initial temperature of fat crystallization and the temperature of the completion of melting were invariably lower
and slightly higher, respectively. Furthermore, in complex food emulsions the supercooling temperature needed to initiate
fat crystallization and the variation in its growth rate in the cooling experiment were dependent on the amount and nature
of the adsorbed proteins. Our results indicate that the total replacement of milk proteins by whey proteins affected the fat
crystallization behavior of emulsified fat droplets, in parallel with changes in their protein surface coverage and in their
physical stability against fat droplet agglomeration. 相似文献
77.
Jonas Amft Philipp M. Meissner Anja Steffen-Heins Mario Hasler Heiko Stöckmann Anne Meynier Lucie Birault Joaquín Velasco Ann Vermoesen Ines Perez-Portabella Blanca Prió Tito Porcellana Emanuele Forte Betül Yesiltas Donny Merkx Marie Hennebelle Jianli Wang John van Duynhoven Sonia Losada-Barreiro Carlos Bravo-Diaz Claudio Bernal Helena Abramovič María J. Manzanos Andrea Martínez-Yusta Bárbara Nieva-Echevarría María D. Guillén Sarah Frühwirth Marc Pignitter Rafał Wołosiak Dorota Derewiaka Marlene Costa Fátima Paiva-Martins Charlotte Jacobsen Karin Schwarz 《European Journal of Lipid Science and Technology》2023,125(10):2300067
Accelerated storage tests are frequently used to assess the oxidative stability of foods and related systems due to its reproducibility. Various methods and experimental conditions are used to measure lipid oxidation. Differences between laboratories make it necessary to determine the repeatability and reproducibility of oxidation tests performed under the same conditions. The objective of the present interlaboratory study was to evaluate the outcome of a storage test for two different bulk oils, sunflower oil (SFO) and rapeseed oil (RSO), during a period of 9 weeks at 20°C, 30°C, 40°C, and 60°C. Sixteen laboratories were provided with bottled oils and conducted the storage tests according to a detailed protocol. Lipid oxidation was monitored by the formation of conjugated dienes (CD) and the activation energy (Ea) was determined for comparative purposes and statistically evaluated. An increase in CD formation was observed for both oils when the storage temperature was increased in all laboratories. The Ea,1 ranged from 47.9 to 73.3 kJ mol−1 in RSO and from 27.8 to 62.6 kJ mol−1 in SFO, with average values of 58.2 and 46.8 kJ mol−1, respectively. The reproducibility coefficients were 10.9% and 18.2% for RSO and SFO, respectively. Practical applications: In order to compare results on oxidative stability of foods derived from different studies, the reproducibility of storage tests and methods employed to evaluate the oxidation level should be considered. This study provides fundamental data on the reproducibility of lipid oxidation under accelerated storage conditions and defines important parameters to be considered for the conduction of experiments. 相似文献
78.
SiC-based fibers are subjected to slow crack growth, a crack growth mechanism activated by stresses and the chemical environment, as identified by static fatigue testing. Such tests can be performed on filaments or bundles. Although both types of specimens show a similar lifetime variation, testing of bundles is often preferred. This work compares the scatter of lifetimes predicted for filaments and for tows using a dedicated Monte Carlo simulation tool relying on the following hypotheses: The stress applied to a single filament can be defined, whereas the size of its most critical flaw cannot; on a bundle, neither the applied stress nor the strength of the critical filament (which triggers the cascade failure and the tow failure) can be defined. Depending on the parallelism of fibers inside the bundle and their strength dispersion, the lifetime scatter can be narrower for filaments compared to tows or vice versa. 相似文献
79.
Jean‐Marie Ringeard Pascal Griesmar Emmanuel Caplain Magalie Michiel Stéphane Serfaty Jean‐Yves Le Huerou Desislava Marinkova Lyubov Yotova 《应用聚合物科学杂志》2013,130(2):835-841
To incorporate microorganisms and to preserve their integrity, new matrices of poly(N‐acryloylglycine) have been designed under appropriate conditions. To understand the interactions between the microorganisms and the organic part of the matrices, different conetworks of poly(N‐acryloylglycine) have been synthesized and characterized. Copolymerization with two crosslinkers was performed with different compositions. The thermal and swelling properties of conetworks are specifically controlled and compared. These investigations show that the swelling ratio of these materials is compatible with the incorporation of biomolecules in these matrices. They successfully permit Pseudomonasspecies 1625 bacteria incorporation. The biological activity of bacteria is also preserved, allowing the use of these materials for innovative biological applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 835‐841, 2013 相似文献
80.
Dr. Shixin Ye Morgane Riou Stéphanie Carvalho Dr. Pierre Paoletti 《Chembiochem : a European journal of chemical biology》2013,14(2):230-235
Heterologous expression of ligand‐gated ion channels (LGICs) in Xenopus laevis oocytes combined with site‐directed mutagenesis has been demonstrated to be a powerful approach to study structure–function relationships. In particular, introducing unnatural amino acids (UAAs) has enabled modifications that are not found in natural proteins. However, the current strategy relies on the technically demanding in vitro synthesis of aminoacylated suppressor tRNA. We report here a general method that circumvents this limitation by utilizing orthogonal aminoacyl‐tRNA synthetase (aaRS)/suppressor tRNACUA pairs to genetically encode UAAs in Xenopus oocytes. We show that UAAs inserted in the N‐terminal domain of N‐methyl‐D ‐aspartate receptors (NMDARs) serve as photo‐crosslinkers that lock the receptor in a discrete conformational state in response to UV photo treatment. Our method should be generally applicable to studies of other LGICs in Xenopus oocytes. 相似文献