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61.
Science China Information Sciences -  相似文献   
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Water Resources Management - Improving drinking water source monitoring is crucial for efficiently managing the drinking water treatment process and ensuring the delivery of safe water. Data mining...  相似文献   
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Accurate measurement of phosphatidylinositol-specific phospholipase C (PI-PLC) activity is important in view of the key role of this enzyme in signal-transduction pathways. In this work we synthesized enantiomerically pure phosphorothiolate analogues of all natural PI-PLC substrates, including those of phosphatidylinositol 4,5-bisphosphate (PI-4,5-P2), 4-phosphate (PI-4-P), 5-phosphate (PI-5-P) and unphosphorylated PI, in both long- and short-chain versions. The enzymatic cleavage of these substrates produces thiol analogues of diacyl glycerol, which can be quantified by UV absorbance after treatment with dipyridyl disulfide. The monodisperse dihexanoyl derivatives are suitable substrates for PI-PLC assay: they give rise to high enzyme activity, and provide excellent linear kinetic responses. For all substrates, we found a good linear correlation between the reaction rate and the amount of enzyme; this indicated the suitability of this assay for enzyme quantification. The short-chain substrates enable the enzyme specificity with variously phosphorylated inositol head groups to be established--unobstructed by substrate aggregation, "scooting" kinetics on micelles, or surface dilution effects. The kinetic results indicated allosteric behavior of PLC for all substrates tested. We found that substrates phosphorylated at the inositol 4-position (phosphorothiolate analogues of PI-4,5-P2 and PI-4-P) displayed very similar kinetic properties, and were cleaved with approximately 20- to 30-fold higher activity than the 4-nonphosphorylated substrates (analogues of PI-5-P and PI). Hence it appears that interactions between the enzyme and the 4-phosphate group of the substrate, but not its 5-phosphate group, is important for PI-PLC catalysis. In addition, the binding affinities of all four substrate types were found to be quite similar; this indicates that the energy of enzyme interaction with the 4-phosphate group is directed almost entirely to catalysis.  相似文献   
64.
The paper presents a model of a reference wind farm. The model considers the wind and wave climatologies for a specific site from which two different wind farm layouts are derived. These layouts are examined through the effective wake‐enhanced turbulence intensity at the hub height for a given climatology, and a simple model for the influence on capital expenditures is proposed. An electrical design is presented, the cable losses are calculated and the energy yield is determined. An operation and maintenance model is established, and the associated operating expenditure is obtained. All of the models are then summarized in terms of a levelized cost of energy using a numerical simulation tool, which allows the layouts to be compared. The data and models are freely available online for others to use and may serve as a baseline for benchmarking and allow researchers to compare and discuss their results. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   
65.
Polybetaines, that have moieties bearing both cationic (quaternary ammonium group) and anionic groups (carboxylate, sulfonate, phosphate/phosphinate/phosphonate groups) situated in the same structural unit represent an important class of smart polymers with unique and specific properties, belonging to the family of zwitterionic materials. According to the anionic groups, polybetaines can be divided into three major classes: poly(carboxybetaines), poly(sulfobetaines) and poly(phosphobetaines). The structural diversity of polybetaines and their special properties such as, antifouling, antimicrobial, strong hydration properties and good biocompatibility lead to their use in nanotechnology, biological and medical fields, water remediation, hydrometallurgy and the oil industry. In this review we aimed to highlight the recent developments achieved in the field of biomedical applications of polybetaines such as: antifouling, antimicrobial and implant coatings, wound healing and drug delivery systems.  相似文献   
66.
This paper reports on a novel method for quantifying the cortical activity of a patient during general anesthesia as a surrogate measure of the patient's level of consciousness. The proposed technique is based on the analysis of a single-channel (frontal) electroencephalogram (EEG) signal using stationary wavelet transform (SWT). The wavelet coefficients calculated from the EEG are pooled into a statistical representation, which is then compared to two well-defined states: the awake state with normal EEG activity, and the isoelectric state with maximal cortical depression. The resulting index, referred to as the wavelet-based anesthetic value for central nervous system monitoring (WAV(CNS)), quantifies the depth of consciousness between these two extremes. To validate the proposed technique, we present a clinical study which explores the advantages of the WAV(CNS) in comparison with the BIS monitor (Aspect Medical Systems, MA), currently a reference in consciousness monitoring. Results show that the WAV(CNS) and BIS are well correlated (r = 0.969) during periods of steady-state despite fundamental algorithmic differences. However, in terms of dynamic behavior, the WAV(CNS) offers faster tracking of transitory changes at induction and emergence, with an average lead of 15-30 s. Furthermore, and conversely to the BIS, the WAV(CNS) regains its preinduction baseline value when patients are responding to verbal command after emergence from anesthesia. We conclude that the proposed analysis technique is an attractive alternative to BIS monitoring. In addition, we show that the WAV(CNS) dynamics can be modeled as a linear time invariant transfer function. This index is, therefore, well suited for use as a feedback sensor in advisory systems, closed-loop control schemes, and for the identification of the pharmacodynamic models of anesthetic drugs.  相似文献   
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In this paper, we present a formulation of highly correlated Fock-space multi-reference coupled-cluster (FSMRCC) methods, including approximate triples on top of the FSMRCC with singles and doubles, which correct the electron affinities by at least at third and up to the fourth order in perturbation. We discuss various partial fourth-order schemes, which are reliable and yet computationally more efficient than the full fourth-order triples scheme. The third-order scheme is called MRCCSD+T*(3). We present two approximate fourth-order schemes, MRCCSD+T*−a(4) and MRCCSD+T*(4). The results that are presented allow one to choose an appropriate fourth-order scheme, which is less expensive and right for the problem. All these schemes are based on the effective Hamiltonian scheme, and provide a direct calculation of the vertical electron affinities. We apply these schemes to a prototype Li2 molecule, using four different basis sets, as well as BeO and CH+. We have calculated the vertical electron affinities of Li2 at the geometry of the neutral Li2 molecule. We also present the vertical ionization potentials of the Li2 anion at the geometry of the anion ground state. We have also shown how to calculate adiabatic electron affinity, though in that case we lose the advantages of direct calculation. BeO has been examined in two basis sets. For CH+, four different basis sets have been used. We have presented the partial fourth-order schemes to the EA in all the basis sets. The results are analyzed to illustrate the importance of triples, as well as highlight computationally efficient partial fourth-order schemes. The choice of the basis set on the electron affinity calculation is also emphasized. Comparisons with available experimental and theoretical results are presented. The general fourth-order schemes, which are conceptually equivalent with the Fock-space multi-reference coupled-cluster singles, doubles, and triplets (MRCCSD+T) methods, based on bondonic formalism, are also presented here in a composed way, for quantum electronic affinity.  相似文献   
70.
Abstract

High-quality thermoelectric La0.2Sr0.8TiO3 (LSTO) films, with thicknesses ranging from 20 nm to 0.7 μm, have been epitaxially grown on SrTiO3(001) substrates by enhanced solid-source oxide molecular-beam epitaxy. All films are atomically flat (with rms roughness < 0.2 nm), with low mosaicity (<0.1°), and present very low electrical resistivity (<5 × 10?4 Ω cm at room temperature), one order of magnitude lower than standard commercial Nb-doped SrTiO3 single-crystalline substrate. The conservation of transport properties within this thickness range has been confirmed by thermoelectric measurements where Seebeck coefficients of approximately –60 μV/K have been recorded for all films. These LSTO films can be integrated on Si for non-volatile memory structures or opto-microelectronic devices, functioning as transparent conductors or thermoelectric elements.  相似文献   
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