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排序方式: 共有818条查询结果,搜索用时 15 毫秒
121.
Singh Y Dolphin GT Razkin J Dumy P 《Chembiochem : a European journal of chemical biology》2006,7(9):1298-1314
The creation of molecular systems that can mimic some of the properties of natural macromolecules is one of the major endeavors in contemporary protein chemistry. However, the construction of artificial proteins with predetermined structure and function is difficult on account of complex folding pathways. The use of topological peptide templates has been suggested to induce and stabilize defined secondary and tertiary structures. This is because the recent advances in the chemistry of coupling reagents, protecting groups, and solid-phase synthesis have made the chemical synthesis of peptides with conformationally controlled and complex structures feasible. Besides their use as structure-inducing devices, these peptide templates can also be utilized to construct novel structures with tailor-made functions. Herein, we present recent advances in the field of peptide-template-based approaches with particular emphasis on the demonstrated utility of this approach in molecular recognition, along with related applications. 相似文献
122.
Izquierdo D Martinez A Heras A Lopez-Palacios J Ruiz V Dryfe RA Colina A 《Analytical chemistry》2012,84(13):5723-5730
Spatial scanning spectroelectrochemistry is a new analytical technique that provides spectral information at different distances from an electrified liquid/liquid interface where an electrochemical process takes place. As a proof of concept, we have studied two different electrochemical processes at the electrified liquid/liquid interface: (1) Ru(bpy)(3)(2+) transfer through the water/1,2-dichloroethane interface and (2) electrodeposition of Pd nanoparticles at the water/1,2-dichloroethane interface. The instrumental setup developed consists of a movable slit for the light beam to sample at well-defined positions on both sides of the interface, providing important information about the chemical process occurring. If the slit is scanned at different distances from the interface during an electrochemical experiment, a complete picture of the reactions and equilibria in the diffusion layer can be obtained. For example, in the case of the Ru(bpy)(3)(2+), the experiments show clearly how the complex is transferred from one phase to the other. In the case of electrosynthesis of Pd nanoparticles, it is demonstrated that nanoparticles are not only deposited at the interface but diffuse to the aqueous bulk solution. These in situ observations were confirmed by ex situ experiments using transmission electron microscopy. 相似文献
123.
E. Gemelli J. de Jesus N.H.A. Camargo G.D. de Almeida Soares V.A.R. Henriques F. Nery 《Materials science & engineering. C, Materials for biological applications》2012,32(4):1011-1015
A titanium-based composite with Ca-P phases was prepared in situ by powder metallurgy processing with TiH2 and nanometric β-TCP powders. Crystal phases of the as-fabricated composite are found to be α-Ti, CaTiO3 and TixPy phase(s). The TixPy and CaTiO3 phases resulted from the reaction between titanium and β-TCP at about 1135 °C. The composite presented a mean compressive strength of 635 MPa and a lower contact angle than pure titanium. 相似文献
124.
Chhatre SS Guardado JO Moore BM Haddad TS Mabry JM McKinley GH Cohen RE 《ACS applied materials & interfaces》2010,2(12):3544-3554
The design of robust omniphobic surfaces, which are not wetted by low-surface-tension liquids such as octane (γlv=21.6 mN/m) and methanol (γlv=22.7 mN/m), requires an appropriately chosen surface micro/nanotexture in addition to a low solid-surface energy (γsv). 1H,1H,2H,2H-Heptadecafluorodecyl polyhedral oligomeric silsesquioxane (fluorodecyl POSS) offers one of the lowest solid-surface energy values ever reported (γsv≈10 mN/m) and has become the molecule of choice for coating textured surfaces. In this work, we synthesize and evaluate a series of related molecules that either retain the POSS cage and differ in fluoroalkyl chain length or that retain the fluorodecyl chains surrounding a linear or cyclic molecular structure. The solid-surface energy (γsv) of these molecules was estimated using contact angle measurements on flat spin-coated silicon wafer surfaces. Zisman analysis was performed using a homologous series of n-alkanes (15.5≤γlv≤27.5 mN/m), whereas Girifalco-Good analysis was performed using a set of polar and nonpolar liquids with a wider range of liquid surface tension (15.5≤γlv≤72.1 mN/m). The hydrogen-bond-donating, hydrogen-bond-accepting, polar, and nonpolar (dispersion) contributions to the solid-surface energy of each compound were determined by probing the surfaces using a set of three liquid droplets of either acetone, chloroform, and dodecane or diiodomethane, dimethyl sulfoxide, and water. 相似文献
125.
This paper proposes the implementation of demand response (DR) programmes in large manufacturing facilities featuring distributed wind and solar energy. Manufacturing facilities are high consumers of electric power. For this reason, these facilities usually pay exorbitant utility bills, which could be as much as $10–20 million per year. A high consumption of electricity also means that upstream fossil-fuelled power plants must release thousands of metric tonnes of carbon annually during the generation of electricity. DR contracts offer a lower utility rate in return for a load reduction during contingent events (i.e. peak hours). This paper covers the modelling and implementation of an interruptible/curtailable DR programme participated by a manufacturer that possesses onsite renewable generation units. These complementary energy resources allow the manufacturer to meet the curtailment requirements without causing any major electricity shortage that adversely affects the normal production schedule. We developed a stochastic programming model to determine the capacity of the wind turbine and solar panels that maximise the DR programme savings. The optimal solutions are derived based on central composite design methodology. 相似文献
126.
Rafael Urrea Jesus Alvarez Jose Alvarez-Ramirez 《Chemical Engineering Communications》2008,195(7):803-820
In this article we explore the application of linear PI cascade control schemes to improve the performance of industrial PI/PID controllers for controlling outlet reactor concentration. By departing from simple I/O first-order dynamical models obtained from step responses, it is shown that the incorporation of a secondary loop for regulating the reactor temperature at a given interior position significantly improves the control performance in the face of feed composition and temperature disturbances. The effects of the temperature sensor location and the usage of multiple temperature measurements are also evaluated. 相似文献
127.
Abstract: The fatigue damage accumulation behaviour of the P355NL1 steel is characterised using block loading fatigue tests. First, the constant amplitude low‐cycle fatigue behaviour of the P355NL1 steel is evaluated through strain‐controlled fatigue tests of smooth specimens. Both fatigue and cyclic elastoplastic behaviours are analysed. Then, block loading is applied to identify the key features of the fatigue damage accumulation phenomena for the P355NL1 steel. The block loading is composed of two distinct low‐cycle constant amplitude strain‐controlled blocks. The first block is applied for a predefined number of loading cycles, being followed by a second block which is applied until failure. The block loading illustrates that fatigue damage evolves nonlinearly with the number of load cycles as a function of the strain amplitude. These observations suggest a nonlinear damage accumulation rule with load sequence effects. The linear Palmgren–Miner's rule used extensively in design is not verified for the P355NL1 steel. Finally, using the generated experimental data, the cyclic elastoplastic behaviour of the P355NL1 steel is modelled using a continuum plasticity model with nonlinear kinematic hardening, available in the commercial finite element code ansys ®. 相似文献
128.
Jesus Guardiola Jose M. Aragón Guadalupe Ramos Rosario Elvira Daniel Martín 《American Institute of Chemical Engineers》2012,58(12):3645-3652
The fine tuning of a sensor designed to locate interfaces using a two‐dimensional gas–solid fluidized bed (FB) as reference is described. The sensor works through computer vision and consists of a charge coupled device camera that is placed alongside the bed and, as the human eye would do, first establishes a straight segment of the bed's top surface to define the phase boundary and then through pattern recognition continuously scans the interface in search of a similar pattern. The field of view is 582 × 752 pixels2. The experimentally measured Pixel size is 216 × 208 μm2. The device allows for experimentally obtaining the position of the probe with a resolution of ± 0.01 pixels at 25 Hz. We also describe its use to measure the height of the FB and observe a linear relationship with fluidization velocity. © 2012 American Institute of Chemical Engineers AIChE J, 2012 相似文献
129.
Bagci U Yao J Wu A Caban J Palmore TN Suffredini AF Aras O Mollura DJ 《IEEE transactions on bio-medical engineering》2012,59(6):1620-1632
This study presents a novel computer-assisted detection (CAD) system for automatically detecting and precisely quantifying abnormal nodular branching opacities in chest computed tomography (CT), termed tree-in-bud (TIB) opacities by radiology literature. The developed CAD system in this study is based on 1) fast localization of candidate imaging patterns using local scale information of the images, and 2) M?bius invariant feature extraction method based on learned local shape and texture properties of TIB patterns. For fast localization of candidate imaging patterns, we use ball-scale filtering and, based on the observation of the pattern of interest, a suitable scale selection is used to retain only small size patterns. Once candidate abnormality patterns are identified, we extract proposed shape features from regions where at least one candidate pattern occupies. The comparative evaluation of the proposed method with commonly used CAD methods is presented with a dataset of 60 chest CTs (laboratory confirmed 39 viral bronchiolitis human parainfluenza CTs and 21 normal chest CTs). The quantitative results are presented as the area under the receiver operator characteristics curves and a computer score (volume affected by TIB) provided as an output of the CAD system. In addition, a visual grading scheme is applied to the patient data by three well-trained radiologists. Interobserver and observer-computer agreements are obtained by the relevant statistical methods over different lung zones. Experimental results demonstrate that the proposed CAD system can achieve high detection rates with an overall accuracy of 90.96%. Moreover, correlations of observer-observer (R(2)=0.8848, and observer-CAD agreements (R(2)=0.824, validate the feasibility of the use of the proposed CAD system in detecting and quantifying TIB patterns. 相似文献