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排序方式: 共有953条查询结果,搜索用时 15 毫秒
61.
Ewa Bogel-?ukasik Susana Santos Manuel Nunes da Ponte 《The Journal of Supercritical Fluids》2010,54(2):210-12548
Ionic liquids as coated catalysts or additives tremendously alter the selectivity pattern of the heterogeneous solid catalyst in the selective hydrogenation of limonene. The conventional monometallic ruthenium over alumina catalyst combined with an ionic liquid enables the one-pot synthesis of the intermediate p-menthene through limonene hydrogenation in supercritical carbon dioxide. Among eight screened imidazolium ILs, [C10mim]NTf2 was employed as additive, or as the coating agent of ruthenium catalyst in the reaction under supercritical conditions.The coating of the heterogeneous catalyst allows the selective production of p-menthene and increases the conversion level of limonene (>99%) compared to the conversion of limonene in the reaction carried out in the presence of an ionic liquid as an additive. Results of the catalyst recycling indicate that there is no depletion of catalyst reactivity even after four successive cycles of operation under the studied reaction conditions. Further hydrogenation of p-menthene is strongly inhibited by employing an ionic liquid. The solubility of limonene or p-menthene in an ionic liquid governs the selective hydrogenation of limonene towards p-menthene. 相似文献
62.
Large-scale applications can be expressed as a set of tasks with data dependencies between them, also known as application
workflows. Due to the scale and data processing requirements of these applications, they require Grid computing and storage
resources. So far, the focus has been on developing easy to use interfaces for composing these workflows and finding an optimal
mapping of tasks in the workflow to the Grid resources in order to minimize the completion time of the application. After
this mapping is done, a workflow execution engine is required to run the workflow over the mapped resources. In this paper,
we show that the performance of the workflow execution engine in executing the workflow can also be a critical factor in determining
the workflow completion time. Using Condor as the workflow execution engine, we examine the various factors that affect the
completion time of a fine granularity astronomy workflow. We show that changing the system parameters that influence these
factors and restructuring the workflow can drastically reduce the completion time of this class of workflows. We also examine
the effect on the optimizations developed for the astronomy application on a coarser granularity biology application. We were
able to reduce the completion time of the Montage and the Tomography application workflows by 90% and 50%, respectively. 相似文献
63.
Ewa Dryzek 《Journal of Materials Science》2003,38(18):3755-3763
The paper presents the experimental results of positron annihilation measurements of the subsurface zones in aluminum and aluminum alloy exposed to the indentation of the small steel ball or blasting by the silicon carbide particles. The measurements of the Doppler broadening of the annihilation line and positron lifetime (PL) enabled the depth profile of open volume defects induced by indentation and blasting processes to be obtained. The coincidence of the von Mises criterion for yield with the onset of the increase of the defect concentration at certain depth was detected. It was established that the defects created in the pure aluminum and the aluminum alloy detected by positrons are different. However, the kinds of induced defects do not change with depth. The PL measurements indicate the presence of vacancy clusters in samples exposed to blasting. The vacancy clusters created in the aluminum alloy are larger than in the pure aluminum. 相似文献
64.
Quantification of Protein‐Induced Membrane Remodeling Kinetics In Vitro with Lipid Multilayer Gratings
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Troy W. Lowry Plengchart Prommapan Aubrey Kusi‐Appiah Nicholas Vafai Ewa A. Bienkiewicz David H. Van Winkle Scott M. Stagg Steven Lenhert 《Small (Weinheim an der Bergstrasse, Germany)》2016,12(4):506-515
The dynamic self‐organization of lipids in biological systems is a highly regulated process that enables the compartmentalization of living systems at micro‐ and nanoscopic scales. Consequently, quantitative methods for assaying the kinetics of supramolecular remodeling such as vesicle formation from planar lipid bilayers or multilayers are needed to understand cellular self‐organization. Here, a new nanotechnology‐based method for quantitative measurements of lipid–protein interactions is presented and its suitability for quantifying the membrane binding, inflation, and budding activity of the membrane‐remodeling protein Sar1 is demonstrated. Lipid multilayer gratings are printed onto surfaces using nanointaglio and exposed to Sar1, resulting in the inflation of lipid multilayers into unilamellar structures, which can be observed in a label‐free manner by monitoring the diffracted light. Local variations in lipid multilayer volume on the surface is used to vary substrate availability in a microarray format. A quantitative model is developed that allows quantification of binding affinity (K D) and kinetics (kon and koff). Importantly, this assay is uniquely capable of quantifying membrane remodeling. Upon Sar1‐induced inflation of single bilayers from surface supported multilayers, the semicylindrical grating lines are observed to remodel into semispherical buds when a critical radius of curvature is reached. 相似文献
65.
Learning-based algorithms in scheduling 总被引:1,自引:1,他引:0
Ewa Dudek-Dyduch 《Journal of Intelligent Manufacturing》2000,11(2):135-143
The aim of the paper is to present a conception of intelligent learning-based algorithms for scheduling. A general knowledge based model of a vast class of discrete deterministic processes is given. The model is a basis for the method of the synthesis of intelligent, learning-based algorithms, that is described in the paper. The designing simulation experiments that use learning is also described. To illustrate the presented ideas, the scheduling algorithm for a special NP-hard problem is given. The significant feature of the problem is that the retooling time depends not only on a pair of jobs to be processed directly one after the other, but also on the subset of jobs already performed. The proof of the NP-hardness of the problem is also given in the paper. 相似文献
66.
Andrzej Huczko Hubert Lange Ewa Ca ko Hanna Grubek-Jaworska Pawe Droszcz 《Fullerenes, Nanotubes and Carbon Nanostructures》2001,9(2):251-254
To determine whether carbon nanotubes can induce any significant health hazards we applied methods routinely used in the pathophysiological testing of asbestos-induced disease to show that the soot with a high content of CNTs does not induce any abnormalities of pulmonary function or measurable inflammation in guinea pigs treated with carbon nanotubes. 相似文献
67.
Ewa Wckelgrd 《Solar Energy Materials & Solar Cells》1998,56(1):1
Black nickel coatings electroplated in a nickel- and sodium chlorine aqueous solution have been prepared and parameters in the process have been optimized to achieve optimal solar selectivity. The best result is a solar absorptance of 0.96 and a thermal emittance of 0.10, as also has been obtained previously for the same type of coating 1H(15N, αγ)12C nuclear resonance reaction (NRR) have contributed with new information about surface chemical composition, morphology and atomic composition in depth profile. These investigations reveal that the coating is porous and contains mainly metallic nickel at the substrate–coating interface and mainly nickel hydroxide at the front surface.The stability of the coating has been tested regarding high-temperature and condensation at high humidity. It has been found that the solar absorptance changes initially, during the first hour of exposure at high temperature, but will then stabilize. Condensation causes a more severe attack on the coating by cracking it. This is contradictory to the results from previous tests at high temperature and humidity in which the black nickel coating was found to be resistant 相似文献
68.
Wioletta Florkiewicz Dagmara Malina Klaudia Pluta Karolina Rudnicka Adrian Gajewski Ewa Olejnik Boena Tyliszczak Agnieszka SobczakKupiec 《IET nanobiotechnology / IET》2019,13(7):726
The study was focused on the phytochemicals‐mediated biosynthesis of silver nanoparticles using leaf extracts and infusions from Cynara scolymus. To identify the antioxidant activity and total phenolic content, the 1,1‐diphenyl‐1‐picrylhydrazyl and Folin–Ciocalteau methods were applied, respectively. The formation and stability of the reduced silver ions were monitored by UV–vis spectrophotometer. The particle sizes of the silver nanoparticles were characterised using the dynamic light scattering technique and scanning electron microscope. The phase composition of the obtained silver nanoparticles was characterised by X‐ray diffraction. The silver nanoparticles suspension, artichoke infusion, and silver ions were separately tested towards potential cytotoxicity and pro‐inflammatory effect using mouse fibroblasts and human monocytes cell line, respectively. The total phenolic content and antioxidant activity of ethanol extract and infusion were found significantly higher as compared to aqueous extract and infusion. The UV–visible spectrophotometric analysis revealed the presence of the characteristic absorption band of the Ag nanoparticles. Moreover, it was found that with the increasing volume of plant extract, the average size of particles was increased. Biocompatibility results evidently showed that silver nanoparticles do not induce monocyte activation, however in order to avoid their cytotoxicity suspension at a concentration <2 ppm should be applied.Inspec keywords: pharmaceuticals, health and safety, renewable materials, toxicology, organic compounds, antibacterial activity, X‐ray diffraction, nanomedicine, nanoparticles, nanofabrication, suspensions, ultraviolet spectra, visible spectra, scanning electron microscopy, silver, particle sizeOther keywords: phytochemicals‐mediated biosynthesis, antioxidant activity, total phenolic content, dynamic light scattering technique, silver nanoparticles suspension, scanning electron microscopy, Cynara scolymus, 1,1 diphenyl‐1‐picrylhydrazyl method, cytotoxicity, immune compatibility, leaf extracts, UV‐vis spectrophotometry, particle size, Folin‐Ciocalteau methods, phase composition, X‐ray diffraction, artichoke infusion, pro‐inflammatory effect, mouse fibroblasts, human monocytes cell line, Ag 相似文献
69.
Ewa Cieślik Teresa Leszczyńska Agnieszka Filipiak-Florkiewicz Elżbieta Sikora Paweł M. Pisulewski 《Food chemistry》2007,105(3):976-981
Effects of blanching, boiling and freezing of selected cruciferous vegetables (Brussels sprouts, white and green cauliflower, broccoli, and curly cale) on their glucosinolate (GLS) contents were determined. It was found that blanching and cooking of the vegetables led to considerable (P < 0.05) losses of total GLS, from 2.7 to 30.0% and from 35.3 to 72.4%, respectively. No systematic changes in total GLS were found in the vegetables that were blanched and frozen for 48 h. In addition, the highest concentration of cancer-protective compounds, such as aliphatic and indole GLS, were found in Brussels sprouts (sinigrin and glucobrassicin) and in broccoli (glucoraphanin). 相似文献
70.
Electrodeposited Ni/SiC composite coatings were obtained in a Watts-type bath. The effect of fine SiC particles on polarization curves of the cathodic reduction of nickel ions was discussed. The incorporation of the particles into the deposit with respect to current density and SiC concentration in the bath was tested. Cathodic current efficiencies were also calculated. Structure of as-plated and heat-treated Ni/SiC composites were examined by means of metallography observations as well as scanning and transmission electron microscopy methods. Two phase transformations in the temperatures range of 20-700 °C were found. For annealed samples, Ni2Si and Ni3Si2 phases were identified. Hardening of the Ni/SiC composites as a function of the particle content in the deposit and annealing temperature was determined by means of the microhardness testing method. 相似文献