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排序方式： 共有379条查询结果，搜索用时 15 毫秒
371.
Achyut Mishra Ram R Panthi Steven L Beckman Khrupa S Vijayaragavan Sanjeev Anand Lloyd E Metzger 《International Journal of Dairy Technology》2023,76(2):364-370
The performance of nanofiltration (NF) as influenced by hydrodynamic cavitation (HC) and filtration temperature during the concentration of milk protein concentrate (MPC) was investigated. Pasteurised skim milk was concentrated using ultrafiltration (UF) to prepare UF retentate (MPC80, 20% total solids, TS), which was then further concentrated using NF at 22°C and 50°C with or without HC treatments until permeate flux declined to 0.1 L/m2/h. Results showed that UF retentate can be concentrated to higher TS (up to 31.5%) at higher filtration temperature or by applying HC, with synergistic effect in combination of both treatments, during NF. 相似文献
372.
Yvonne Kohl Michelle Müller Marielle Fink Marc Mamier Siegfried Fürtauer Roland Drexel Christine Herrmann Stephan Dähnhardt-Pfeiffer Ramona Hornberger Marius I. Arz Christoph Metzger Sylvia Wagner Sven Sängerlaub Heiko Briesen Florian Meier Tobias Krebs 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(23):2207207
In this study, a 96-well exposure system for safety assessment of nanomaterials is developed and characterized using an air–liquid interface lung epithelial model. This system is designed for sequential nebulization. Distribution studies verify the reproducible distribution over all 96 wells, with lower insert-to-insert variability compared to non-sequential application. With a first set of chemicals (TritonX), drugs (Bortezomib), and nanomaterials (silver nanoparticles and (non-)fluorescent crystalline nanocellulose), sequential exposure studies are performed with human lung epithelial cells followed by quantification of the deposited mass and of cell viability. The developed exposure system offers for the first time the possibility of exposing an air–liquid interface model in a 96-well format, resulting in high-throughput rates, combined with the feature for sequential dosing. This exposure system allows the possibility of creating dose-response curves resulting in the generation of more reliable cell-based assay data for many types of applications, such as safety analysis. In addition to chemicals and drugs, nanomaterials with spherical shapes, but also morphologically more complex nanostructures can be exposed sequentially with high efficiency. This allows new perspectives on in vivo-like and animal-free approaches for chemical and pharmaceutical safety assessment, in line with the 3R principle of replacing and reducing animal experiments. 相似文献
373.
Anna S. Schenk Igor Zlotnikov Boaz Pokroy Notburga Gierlinger Admir Masic Paul Zaslansky Andrew N. Fitch Oskar Paris Till H. Metzger Helmut Cölfen Peter Fratzl Barbara Aichmayer 《Advanced functional materials》2012,22(22):4668-4676
Biominerals are complex inorganic‐organic structures that often show excellent mechanical properties. Here a bio‐inspired study of a remarkably simple synthetic system is presented in which only one charged polymer additive (poly(sodium 4‐styrenesulfonate)) is able to induce hierarchical structuring of calcite similar to biominerals. The interaction of the negatively charged polymer with the nucleation and growth of the mineral, in particular via selective adsorption to internal and external (001) facets of the calcite lattice, implies structural features from the micrometer down to the nanometer level. The crystals exhibit a distinct rounded morphology and a controlled orientation. Moreover, the polymer molecules are occluded within the crystals with different concentrations in well‐defined regions. This leads to the induction of a mesoscale structure based on 100 nm sized mineral building blocks with granular substructure and rough surface, as well as small modifications of the crystallographic structure. Such a combination of hierarchically organized structural features has previously only been reported for biogenic calcite, which is typically grown in a complex process involving multiple organic additives. It is also shown that the organic occlusions in the calcite‐PSS hybrid crystals strongly affect the mechanical performance, as known for some biominerals. 相似文献
374.
Miriam J. Metzger Andrew J. Flanagin Ryan B. Medders 《The Journal of communication》2010,60(3):413-439
The tremendous amount of information available online has resulted in considerable research on information and source credibility. The vast majority of scholars, however, assume that individuals work in isolation to form credibility opinions and that people must assess information credibility in an effortful and time‐consuming manner. Focus group data from 109 participants were used to examine these assumptions. Results show that most users rely on others to make credibility assessments, often through the use of group‐based tools. Results also indicate that rather than systematically processing information, participants routinely invoked cognitive heuristics to evaluate the credibility of information and sources online. These findings are leveraged to suggest a number of avenues for further credibility theorizing, research, and practice. 相似文献
375.
Tzuriel Simcha Metzger Ran Tel‐Vered Hendrik Bauke Albada Itamar Willner 《Advanced functional materials》2015,25(41):6470-6477
The electropolymerization of thioaniline‐modified Au nanoparticles (NPs) on thioaniline monolayer‐functionalized electrodes in the presence of Zn(II)‐protoporphyrin IX yields bis aniline‐crosslinked Au NPs matrices that include molecular imprinted sites for binding the Zn(II)‐protoporphyrin IX photosensitizer. The binding of the photosensitizer yields photoelectrochemically active electrodes that produce anodic photocurrents in the presence of the electron donor benzohydroquinone. The efficient photocurrents formed in the presence of the imprinted electrode are attributed to the high‐affinity binding of the photosensitizer to the imprinted sites, Ka = 3.2 × 106 m ?1, and to the effective transport of the photoejected electrons to the bulk electrode via the bridged Au NPs matrix. Similarly, a N,N′‐dialkyl‐4,4′‐bipyridinium‐modified Zn(II)‐protoporphyrin IX photosensitizer‐electron acceptor dyad is imprinted in the bis aniline‐crosslinked Au NPs matrix. The photocurrent generated by the imprinted matrix is approximately twofold higher as compared to the photocurrent generated by the Zn(II)‐protoporphyrin IX‐imprinted Au NPs matrix. The efficient photocurrents generated in the presence of the bipyridinium‐modified Zn(II)‐protoporphyrin IX‐imprinted matrix are attributed to the effective primary charge separation of the electron–hole species in the dyad structure, followed by the effective transport of the photoejected electrons to the electrode via the bis aniline‐crosslinked Au NPs matrix. 相似文献
376.
Robert M. Metzger 《Advanced functional materials》1999,9(6):253-263
A single molecule, γ-hexadecyl-quinolinium tricyanoquinomethanide, 1, whose ground state is zwitterionic: D+-π-A−, with dipole moment 48±8 Debyes, and whose first excited state is undissociated: D0-π-A0, with an estimated moment between 3 and 9 Debyes, is a unimolecular rectifier of electrical current between 370 and 105 K. Spectroscopy data confirm this interpretation. The 1974 proposal by Aviram and Ratner for unimolecular rectification has been confirmed, but questions can still be formulated about experimental details. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
377.
Kurt Metzger 《Transactions on Emerging Telecommunications Technologies》1994,5(2):235-244
The known suboptimal sequential detection methods need a minimum-phase signal as input for achieving good performance. As a consequence the received signal must be first transformed to minimum-phase by an adaptive prefilter if simplified detection methods are applied. This roundabout way is avoided in a novel algorithm for sequential detection, where the metric calculation itself is fitted to the special situation of the compare-and-select procedure. The detection method uses two different metrics, one for comparing paths, which have merged in a common trellis-state, the other for comparing paths which have just emerged from a common state. In this way the usual adaptive prefilter can be saved, because the proposed detector does not require a minimum-phase signal at its input. Simulation results show excellent management of distorted and noisy signals. 相似文献
378.
I. L. Repins B. J. Stanbery D. L. Young S. S. Li W. K. Metzger C. L. Perkins W. N. Shafarman M. E. Beck L. Chen V. K. Kapur D. Tarrant M. D. Gonzalez D. G. Jensen T. J. Anderson X. Wang L. L. Kerr B. Keyes S. Asher A. Delahoy B. Von Roedern 《Progress in Photovoltaics: Research and Applications》2006,14(1):25-43
We report the results of an extensive study employing numerous methods to characterize carrier transport within copper indium gallium sulfoselenide (CIGSS) photovoltaic devices, whose absorber layers were fabricated by diverse process methods in multiple laboratories. This collection of samples exhibits a wide variation of morphologies, compositions, and solar power conversion efficiencies. An extensive characterization of transport properties is reported here—including those derived from capacitance–voltage, admittance spectroscopy, deep level transient spectroscopy, time‐resolved photoluminescence, Auger emission profiling, Hall effect, and drive level capacitance profiling. Data from each technique were examined for correlation with device performance, and those providing indicators of related properties were compared to determine which techniques and interpretations provide credible values for transport properties. Although these transport properties are not sufficient to predict all aspects of current‐voltage characteristics, we have identified specific physical and transport characterization methods that can be combined using a model‐based analysis algorithm to provide a quantitative prediction of voltage loss within the absorber. The approach has potential as a tool to optimize and understand device performance irrespective of the specific process used to fabricate the CIGSS absorber layer. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
379.
Titanium alloys are one of the most important design materials for the aircraft industry.The high strength-to-density-ratio and the compatibility with carbon fibre reinforced plastic are the reasons for a raising application in this field.The outstanding properties lead to challenging machining processes.High strength and low heat conductivity affect high mechanical and thermal loads for the cutting edge.Thus,the machining process is characterized by a rapid development of tool wear even at low cutting parameter.To reach a sufficient productivity it is necessary to dissipate the resulting heat from the cutting edge by a coolant.Therefore the cryogenic machining of two different titanium alloys is investigated in this work.The results point out the different behavior of the machining processes under cryogenic conditions because of the reduced thermal load for the cutting tool.According to this investigation,the cryogenic cooling with CO_2enables an increase of the tool life in comparison to emulsion based cooling principles when machining theα+β-titanium alloy Ti-6Al-4V.The machining process of the high strength titanium alloy Ti-6Al-2Sn-4Zr-6Mo requires an additional lubrication realized by a minimum quantity lubrication(MQL) with oil.This combined cooling leads to a smoother chip underside and to slender shear bands between the different chip segments. 相似文献