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排序方式: 共有736条查询结果,搜索用时 700 毫秒
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Kinetic,thermodynamic parameters and in vitro digestion of tannase from Aspergillus tamarii URM 7115
Amanda Reges de Sena Tonny Cley Campos Leite Talita Camila Evaristo da Silva Nascimento Anna Carolina da Silva Catiane S. Souza Antônio Fernando de Mello Vaz 《Chemical Engineering Communications》2018,205(10):1415-1431
Tannase is an enzyme used in various industries and produced by a large number of microorganisms. The aim of this study was to evaluate tannase production to determine the biochemical, kinetic, and thermodynamic properties and to simulate tannase in vitro digestion. The tannase-producing fungal strain was isolated from “jamun” leaves and identified as Aspergillus tamarii. Temperature at 26°C for 67?h was the best combination for maximum tannase activity (6.35-fold; initial activity in Plackett–Burman design—15.53?U/mL and average final activity in Doehlert design—98.68?U/mL). The crude extract of tannase was optimally active at 40°C, pH 5.5 and 6.5. Moreover, tannase was stimulated by Na+, Ca2+, Mg2+, and Mn2+. The half-life at 40°C lasted 247.55?min. The free energy of Gibbs, enthalpy, and entropy, at 40°C, was 81.47, 16.85, and ?0.21?kJ/mol?·?K, respectively. After total digestion, 123.95% of the original activity was retained. Results suggested that tannase from A. tamarii URM 7115 is an enzyme of interest for industrial applications, such as gallic acid production, additive for feed industry, and for beverage manufacturing, due to its catalytic and thermodynamic properties. 相似文献
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ME Goldberg BW Lex NK Mello JH Mendelson TA Bower 《Canadian Metallurgical Quarterly》1996,66(2):228-238
Research on achievement goal orientation in sport has relied primarily on traditional statistical methodology to examine group mean differences. Unfortunately, examination of the measurement model is generally ignored prior to means testing. This study reports an application of structural equation modeling (SEM) in testing measurement invariance and latent mean structure of the Task and Ego Orientation in Sport Questionnaire (TEOSQ; Duda & Nicholls, 1989) using male and female college students. A confirmatory factor analysis for testing invariance revealed invariant measurement properties and factor structures across gender, indicating that task and ego orientation are similarly conceptualized by male and female students. Subsequent testing of latent mean structures, however, showed significant gender differences with respect to ego orientation, but no difference in task orientation. The SEM procedures used in the present study demonstrate additional construct validity and internal consistency reliability for the TEOSQ and, by confirming its factor structure, provide a sound psychometric basis for its continued use in substantive studies focusing on the comparison of achievement goal orientation across gender. 相似文献
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Generator rotor angle measurement is useful in identification of electric machine parameters in the d and q axes and as an indicator of stability of the operating condition. Rotor angle measurements with the appropriate bandwidth are also very useful in observation of rotor torsional oscillations both for monitoring and protection against undamped torsional modes, and for use in control schemes designed to damp torsional oscillations. A method of measurement of synchronous machine rotor angle from an analysis of the phase angle of zero sequence harmonic components of terminal voltage is presented 相似文献
7.
Mello LV; van Aalten DM; Findlay JB 《Protein engineering, design & selection : PEDS》1997,10(4):381-387
This paper documents the first essential dynamics analysis of ras protein
ligands and of the protein itself, showing important features of their
dynamic properties. Essential dynamics analysis of 300 ps of full solvent
molecular dynamics simulations revealed differences in structure and
dynamics between GDP- and GTP-bound forms of H-ras-p21. Regions in the
protein which exhibited a structural shift correspond to the switch regions
described previously. Differences in dynamics between H-ras-p21 GDP and
H-ras-p21 GTP may be related to interactions of ras with GAP and its
receptor and effector. Molecular dynamics of free GDP (in the absence of
protein) were performed in water for 2 ns and analysed using essential
dynamics. The conformations of GDP and GTP when bound to the protein were
compared with free GDP, revealing that the ligands bind to the protein in
an energetically unfavourable conformation. GDP and GTP molecules from
various other protein crystal structures were also analysed. These ligands
adopt similar conformations to those seen in H-ras-p21.
相似文献
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In recent years, cubic regularization algorithms for unconstrained optimization have been defined as alternatives to trust-region and line search schemes. These regularization techniques are based on the strategy of computing an (approximate) global minimizer of a cubic overestimator of the objective function. In this work we focus on the adaptive regularization algorithm using cubics (ARC) proposed in Cartis et al. [Adaptive cubic regularisation methods for unconstrained optimization. Part I: motivation, convergence and numerical results, Mathematical Programming A 127 (2011), pp. 245–295]. Our purpose is to design a modified version of ARC in order to improve the computational efficiency preserving global convergence properties. The basic idea is to suitably combine a Goldstein-type line search and a nonmonotone accepting criterion with the aim of advantageously exploiting the possible good descent properties of the trial step computed as (approximate) minimizer of the cubic model. Global convergence properties of the proposed nonmonotone ARC algorithm are proved. Numerical experiments are performed and the obtained results clearly show satisfactory performance of the new algorithm when compared to the basic ARC algorithm. 相似文献
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Antonio Negretti Albert Benseny Jordi Mompart Tommaso Calarco 《Quantum Information Processing》2013,12(3):1439-1467
We numerically investigate the performance of atomic transport in optical microtraps via the so called spatial adiabatic passage technique. Our analysis is carried out by means of optimal control methods, which enable us to determine suitable transport control pulses. We investigate the ultimate limits of the optimal control in speeding up the transport process in a triple well configuration for both a single atomic wave packet and a Bose-Einstein condensate within a regime of experimental parameters achievable with current optical technology. 相似文献
10.
A simulation of the profile of holographically recorded structures in photoresists is performed. In addition to its simplicity this simulation can be used to take into account the effects that arise from exposure, photosensitization, development, and resolution of positive photoresists. We analyzed the effects of isotropy of wet development, nonlinearity of the photoresist response curve, background light, and standing waves produced by reflection at the film-substrate interface by using this simulation, and the results agree with the experimentally recorded profiles. 相似文献