排序方式: 共有555条查询结果,搜索用时 0 毫秒
91.
Jürgen Brem Mihaela C. TurcuCsaba Paizs Katri LundellMonica-Ioana To?a Florin-Dan IrimieLiisa T. Kanerva 《Process Biochemistry》2012,47(1):119-126
Lipase AK “Amano” 20 from Pseudomonas fluorescens (PFL) was immobilized using diverse immobilization techniques. The methods developed, especially the optimized sol-gel procedure, enabled the fine tuning of enzymatic activity and enantioselectivity for the kinetic resolution of racemic ethyl 3-aryl-3-hydroxypropanoates. The aryl moieties of the racemates include furan-2 and 3-yl, thiophen-2 and 3-yl, benzofuran-2-yl, benzo[b]thiophen-2-yl, as well as phenyl and 4-chloro- and 4-methoxyphenyl groups. The optimized PFL sol-gel preparation (encapsulation from the aqueous solution of PFL, sucrose and Celite in situ) was shown to be efficiently reusable in ten cycles and highly enantioselective with E > 200 to all other substrates except furan-2 and 3-yl and thiophen-2 and 3-yl substituted compounds with E 108-184. 相似文献
92.
Processing of pre-miRNAs by Dicer is regulated by its dsRNA-binding protein partner, and leads to the generation of alternative miRNA forms with distinct target sets. 相似文献
93.
This paper presents an optimizing start-up strategy for a bio-methanator. The goal of the control strategy is to maximize
the outflow rate of methane in anaerobic digestion processes, which can be described by a two-population model. The methodology
relies on a thorough analysis of the system dynamics and involves the solution of two optimization problems: steady-state
optimization for determining the optimal operating point and transient optimization. The latter is a classical optimal control
problem, which can be solved using the maximum principle of Pontryagin. The proposed control law is of the bang–bang type.
The process is driven from an initial state to a small neighborhood of the optimal steady state by switching the manipulated
variable (dilution rate) from the minimum to the maximum value at a certain time instant. Then the dilution rate is set to
the optimal value and the system settles down in the optimal steady state. This control law ensures the convergence of the
system to the optimal steady state and substantially increases its stability region. The region of attraction of the steady
state corresponding to maximum production of methane is considerably enlarged. In some cases, which are related to the possibility
of selecting the minimum dilution rate below a certain level, the stability region of the optimal steady state equals the
interior of the state space. Aside its efficiency, which is evaluated not only in terms of biogas production but also from
the perspective of treatment of the organic load, the strategy is also characterized by simplicity, being thus appropriate
for implementation in real-life systems. Another important advantage is its generality: this technique may be applied to any
anaerobic digestion process, for which the acidogenesis and methanogenesis are, respectively, characterized by Monod and Haldane
kinetics. 相似文献
94.
95.
The supramolecular organization of photosystem II (PSII) complexes in the photosynthetic membrane of the cyanobacterium Synechocystis 6803 was studied by electron microscopy. After mild detergent solubilization, crystalline PSII arrays were extracted in which dimeric PSII particles associate in multiple rows. Image processing of the arrays shows that the PSII dimers are tightly packed at distances of 12.2 and 16.7 nm. The domains are considered to be an important type of association for preventing either spill-over energy from PSII towards photosystem I (PSI) or direct energy flow from phycobilisomes to PSI, because the latter can only be at periphery of the arrays. 相似文献
96.
Ionut Cardei Srivatsan Varadarajan Allalaghatta Pavan Lee Graba Mihaela Cardei Manki Min 《Cluster computing》2004,7(1):91-103
Boosted by technology advancements, government and commercial interest, ad-hoc wireless networks are emerging as a serious platform for distributed mission-critical applications. Guaranteeing QoS in this environment is a hard problem because several applications may share the same resources in the network, and mobile ad-hoc wireless networks (MANETs) typically exhibit high variability in network topology and communication quality. In this paper we introduce DYNAMIQUE, a resource management infrastructure for MANETs. We present a resource model for multi-application admission control that optimizes the application admission utility, defined as a combination of the QoS satisfaction ratio. A method based on external adaptation (shrinking QoS for existing applications and later QoS expansion) is introduced as a way to reduce computation complexity by reducing the search space. We designed an application admission protocol that uses a greedy heuristic to improve application utility. For this, the admission control considers network topology information from the routing layer. Specifically, the admission protocol takes benefit from a cluster network organization, as defined by ad-hoc routing protocols such as CBRP and LANMAR. Information on cluster membership and cluster head elections allows the admission protocol to minimize control signaling and to improve application quality by localizing task mapping. 相似文献
97.
The inhibition of water diffusion across the rat erythrocyte membrane was studied by NMR using two basically different types of inhibitory agents: PCMB andin vivo irradiation. The contribution of lipid and protein to water permeability revealed the inhibitory effect of each pathway. Internal contamination with tritium (25–115 mGy) reduces water permeability due to protein modifications; for doses higher than 100 mGy the lipid mediated mechanism seems also to be impaired. The same procedure enables one to assess the extent to which the higher water permeability of rat, compared to human, erythrocyte is due to one of the two pathways. 相似文献
98.
99.
100.