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141.
Measurement Techniques - A comparative analysis of the results of estimation of measurement uncertainty is conducted. The results are obtained by a method described in the Handbook on the... 相似文献
142.
Umanskyi O. P. Storozhenko M. S. Koshelev M. V. Antonov M. M. Vasylkivska M. A. Tymofeeva I. I. 《Powder Metallurgy and Metal Ceramics》2019,57(11-12):670-678
Powder Metallurgy and Metal Ceramics - The effect of TiB2 and CrB2 additives on the oxidation behavior of composites made of the NiCrBSiC and FeNiCrBSiC self-fluxing alloys has been studied in air... 相似文献
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Shank S. Kulkarni Kyoo Sil Choi Wenbin Kuang Nalini Menon Bernice Mills Ayoub Soulami Kevin Simmons 《International Journal of Hydrogen Energy》2021,46(36):19001-19022
The use of hydrogen as a fuel is increasing exponentially, and the most economical way to store and transport hydrogen for fuel use is as a high-pressure gas. Polymers are widely used for hydrogen distribution and storage systems because they are chemically inert towards hydrogen. However, when exposed to high-pressure hydrogen, some hydrogen diffuses through polymers and occupies the preexisting cavities inside the material. Upon depressurization, the hydrogen trapped inside polymer cavities can cause blistering or cracking by expanding these cavities. A continuum mechanics–based deformation model was deployed to predict the stress distribution and damage propagation while the polymer undergoes depressurization after high-pressure hydrogen exposure. The effects of cavity size, cavity location, and pressure inside the cavity on damage initiation and evolution inside the polymer were studied. The stress and damage evolution in the presence of multiple cavities was also studied, because interaction among cavities alters the damage and stress field. It was found that all these factors significantly change the stress state in the polymer, resulting in different paths for damage propagation. The effect of adding carbon black filler particles and plasticizer on the damage was also studied. It was found that damage tolerance of the polymer increases drastically with the addition of carbon black fillers, but decreases with the addition of the plasticizer. 相似文献
146.
Dr. Alexander Fries Dr. Laura S. Mazzaferro Dr. Björn Grüning Dr. Philippe Bisel Karin Stibal Patrick C. F. Buchholz Prof. Dr. Jürgen Pleiss Prof. Dr. Georg A. Sprenger Prof. Dr. Michael Müller 《Chembiochem : a European journal of chemical biology》2019,20(13):1672-1677
Chorismate and isochorismate constitute branch-point intermediates in the biosynthesis of many aromatic metabolites in microorganisms and plants. To obtain unnatural compounds, we modified the route to menaquinone in Escherichia coli. We propose a model for the binding of isochorismate to the active site of MenD ((1R,2S, 5S,6S)-2-succinyl-5-enolpyruvyl-6-hydroxycyclohex-3-ene-1-carboxylate (SEPHCHC) synthase) that explains the outcome of the native reaction with α-ketoglutarate. We have rationally designed variants of MenD for the conversion of several isochorismate analogues. The double-variant Asn117Arg–Leu478Thr preferentially converts (5S,6S)-5,6-dihydroxycyclohexa-1,3-diene-1-carboxylate (2,3-trans-CHD), the hydrolysis product of isochorismate, with a >70-fold higher ratio than that for the wild type. The single-variant Arg107Ile uses (5S,6S)-6-amino-5-hydroxycyclohexa-1,3-diene-1-carboxylate (2,3-trans-CHA) as substrate with >6-fold conversion compared to wild-type MenD. The novel compounds have been made accessible in vivo (up to 5.3 g L−1). Unexpectedly, as the identified residues such as Arg107 are highly conserved (>94 %), some of the designed variations can be found in wild-type SEPHCHC synthases from other bacteria (Arg107Lys, 0.3 %). This raises the question for the possible natural occurrence of as yet unexplored branches of the shikimate pathway. 相似文献
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Zakharov A. V. Rozenko S. A. 《Journal of Communications Technology and Electronics》2019,64(4):430-438
Journal of Communications Technology and Electronics - Microstrip band-pass filters (BPFs) containing quarter-wavelength resonators and a Π-shaped half-wavelength resonator placed next to each... 相似文献
149.
Water Resources Management - Public awareness of water quality concerns has increased since the Flint, MI crisis, but knowledge about water resources management remains low. Consequently,... 相似文献
150.
Grishina I. P. Telegin S. V. Lyasnikova A. V. Markelova O. A. Dudareva O. A. 《Metallurgist》2019,63(1-2):215-220
Metallurgist - We propose a combined technology for the modification of the surfaces of titanium implants by laser radiation followed by the plasma spraying of biocompatible coatings. We performed... 相似文献