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991.
992.
Polycyclic aromatic hydrocarbons (PAHs) are generated during smoke curing and other heating treatments of food and represent a large class of chemical pollutants including a number of carcinogens. At present, PAHs are frequently detected by costly and time-consuming chemical analysis. Effect-directed in vitro cell-based bioassays of contaminants can offer a rapid, sensitive, and relatively inexpensive alternative for screening of contaminants in comparison to instrumental analysis. They enable estimation of total biological activity of all compounds acting through the same mode of binding. The aryl hydrocarbon receptor as a binding site plays an important role in PAH-induced carcinogenesis. The in vitro chemical-activated luciferase expression assay (using conditions to detect PAH) was investigated for its applicability for effect-directed analysis of PAH levels in smoked meat. There was an intra-assay variability of 0 to 15% and a mean coefficient of variation of 25% (3 to 50%) for the cleanup and bioassay analysis of the smoked pork samples. There was a correlation between the total responses of the bioassay and the individual amounts of the PAHs with a high molecular weight. The comparison of 2,3,7,8-tetrachlorodibenzo-p-dioxin and benzo[k]fluoranthene used as standard in the in vitro chemical-activated luciferase expression assay resulted in benzo[k]fluoranthene being able to be used as an alternative, nontoxic standard in the bioassay. This bioassay is an applicable effect-directed functional prescreening method for the analysis of PAHs in smoked meat and appears to have potential in being used for food control in the future. 相似文献
993.
Bernhard Mitchell Gerhard Peharz Gerald Siefer Marius Peters Tobias Gandy Jan Christoph Goldschmidt Jan Benick Stefan W. Glunz Andreas W. Bett Frank Dimroth 《Progress in Photovoltaics: Research and Applications》2011,19(1):61-72
A spectral beam‐splitting architecture is shown to provide an excellent basis for a four junction photovoltaic receiver with a virtually ideal band gap combination. Spectrally selective beam‐splitters are used to create a very efficient light trap in form of a 45° parallelepiped. The light trap distributes incident radiation onto the different solar cells with an optical efficiency of more then 90%. Highly efficient solar cells including III–V semiconductors and silicon were fabricated and mounted into the light trapping assembly. An integrated characterization of such a receiver including the measurement of quantum efficiency as well as indoor and outdoor I–V measurements is shown. Moreover, the optical loss mechanisms and the optical efficiency of the spectral beam‐splitting approach are discussed. The first experimental setup of the receiver demonstrated an outdoor efficiency of more than 34% under unconcentrated sunlight. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
994.
酶制剂在苹果汁生产中的作用
在苹果原料的成熟和储存过程中,苹果细胞壁的多糖也在逐步演变,苹果会慢慢变软,一些多糖会部分溶解.这些多糖都具备高度的持水性,能将果汁保持在果浆中,导致可榨性降低,出汁率下降.为了确保苹果出汁率达到最佳水平.必须在榨汁阶段加入果浆酶. 相似文献
995.
Andreas Fischer 《Mathematics of Control, Signals, and Systems (MCSS)》1997,10(3):223-236
We show that for infinite-dimensional discrete-time positive systems the complex and real stability radii coincide. Furthermore, we provide a simple formula for the complex stability radius of positive systems by the associated transfer function. We illustrate our results with an example dealing with a simple type of differential-difference equations.The author would like to thank the Deutsche Forschungsgemeinschaft for its support during this work. 相似文献
996.
Marco Sarcletti Dustin Vivod Tobias Luchs Tobias Rejek Luis Portilla Lukas Müller Hanno Dietrich Andreas Hirsch Dirk Zahn Marcus Halik 《Advanced functional materials》2019,29(15)
Various hydrocarbons are efficiently extracted from water by using a new sorbent material based on covalently functionalized magnetic nanoparticles. The functionalization of the magnetite nanoparticles with a self‐assembled monolayer of hexadecylphosphonic acid renders the nanoparticles oleophilic and the magnetic nature of magnetite allows for simple extraction of the hydrocarbon‐soaked sorbent. The sorbent material is capable of extracting single contaminants such as alkanes and aromatics and complex hydrocarbon mixtures such as crude oils in high extraction rates of up to 14 times the sorbent volume. Experimental results are explained by molecular dynamics simulations on the adsorption of single components from a hydrocarbon‐water mixture to the alkylphosphonic acid layer on the nanoparticles. The core–shell sorbent material is highly stable and therefore, reusable over several successive extraction cycles without degradation. The extraction performance is determined at different water temperatures, different water sources, and different magnetic core materials and evaluated compared to heptadecanoic acid functionalized magnetite. The new sorbent material provides the opportunity for an efficient, reliable, inexpensive, and environmental friendly removal of hydrocarbons from water. 相似文献
997.
Amir Sammak Diego Sabbagh Nico W. Hendrickx Mario Lodari Brian Paquelet Wuetz Alberto Tosato LaReine Yeoh Monica Bollani Michele Virgilio Markus Andreas Schubert Peter Zaumseil Giovanni Capellini Menno Veldhorst Giordano Scappucci 《Advanced functional materials》2019,29(14)
Buried‐channel semiconductor heterostructures are an archetype material platform for the fabrication of gated semiconductor quantum devices. Sharp confinement potential is obtained by positioning the channel near the surface; however, nearby surface states degrade the electrical properties of the starting material. Here, a 2D hole gas of high mobility (5 × 105 cm2 V?1 s?1) is demonstrated in a very shallow strained germanium (Ge) channel, which is located only 22 nm below the surface. The top‐gate of a dopant‐less field effect transistor controls the channel carrier density confined in an undoped Ge/SiGe heterostructure with reduced background contamination, sharp interfaces, and high uniformity. The high mobility leads to mean free paths ≈ 6 µm, setting new benchmarks for holes in shallow field effect transistors. The high mobility, along with a percolation density of 1.2 × 1011cm?2, light effective mass (0.09me), and high effective g‐factor (up to 9.2) highlight the potential of undoped Ge/SiGe as a low‐disorder material platform for hybrid quantum technologies. 相似文献
998.
Kolleboyina Jayaramulu Deepak P. Dubal Andreas Schneemann Vclav Ranc Cecilia Perez‐Reyes Jana Strsk tpn Kment Michal Otyepka Roland A. Fischer Radek Zboil 《Advanced functional materials》2019,29(38)
Herein, a novel polymer‐templated strategy is described to obtain 2D nickel‐based MOF nanosheets using Ni(OH)2, squaric acid, and polyvinylpyrrolidone (PVP), where PVP has a dual role as a structure‐directing agent, as well as preventing agglomeration of the MOF nanosheets. Furthermore, a scalable method is developed to transform the 2D MOF sheets to Ni7S6/graphene nanosheet (GNS) heterobilayers by in situ sulfidation using thiourea as a sulfur source. The Ni7S6/GNS composite shows an excellent reversible capacity of 1010 mAh g?1 at 0.12 A g?1 with a Coulombic efficiency of 98% capacity retention. The electrochemical performance of the Ni7S6/GNS composite is superior not only to nickel sulfide/graphene‐based composites but also to other metal disulfide–based composite electrodes. Moreover, the Ni7S6/GNS anode exhibits excellent cycle stability (≈95% capacity retention after 2000 cycles). This outstanding electrochemical performance can be attributed to the synergistic effects of Ni7S6 and GNS, where GNS serves as a conducting matrix to support Ni7S6 nanosheets while Ni7S6 prevents restacking of GNS. This work opens up new opportunities in the design of novel functional heterostructures by hybridizing 2D MOF nanosheets with other 2D nanomaterials for electrochemical energy storage/conversion applications. 相似文献
999.
Matthias Diethelm Andreas Schiller Maciej Kawecki Andrius Deviis Balthasar Blülle Sandra Jenatsch Evelyne Knapp Quirin Grossmann Beat Ruhstaller Frank Nüesch Roland Hany 《Advanced functional materials》2020,30(33)
In light‐emitting electrochemical cells (LECs), the position of the emission zone (EZ) is not predefined via a multilayer architecture design, but governed by a complex motion of electrical and ionic charges. As a result of the evolution of doped charge transport layers that enclose a dynamic intrinsic region until steady state is reached, the EZ is often dynamic during turn‐on. For thick sandwich polymer LECs, a continuous change of the emission color provides a direct visual indication of a moving EZ. Results from an optical and electrical analysis indicate that the intrinsic zone is narrow at early times, but starts to widen during operation, notably well before the electrical device optimum is reached. Results from numerical simulations demonstrate that the only precondition for this event to occur is that the mobilities of anions (μa) and cations (μc) are not equal, and the direction of the EZ shift dictates μc > μa. Quantitative ion profiles reveal that the displacement of ions stops when the intrinsic zone stabilizes, confirming the relation between ion movement and EZ shift. Finally, simulations indicate that the experimental current peak for constant‐voltage operation is intrinsic and the subsequent decay does not result from degradation, as commonly stated. 相似文献
1000.
Effect of alternating postures on cognitive performance for healthy people performing sedentary work
Bernhard Schwartz Jay M. Kapellusch Andreas Schrempf Kathrin Probst Michael Haller Arnold Baca 《Ergonomics》2018,61(6):778-795
Prolonged sitting is a risk factor for several diseases and the prevalence of worksite-based interventions such as sit-to-stand workstations is increasing. Although their impact on sedentary behaviour has been regularly investigated, the effect of working in alternating body postures on cognitive performance is unclear. To address this uncertainty, 45 students participated in a two-arm, randomised controlled cross-over trial under laboratory conditions. Subjects executed validated cognitive tests (working speed, reaction time, concentration performance) either in sitting or alternating working postures on two separate days (ClinicalTrials.gov Identifier: NCT02863731). MANOVA results showed no significant difference in cognitive performance between trials executed in alternating, standing or sitting postures. Perceived workload did not differ between sitting and alternating days. Repeated measures ANOVA revealed significant learning effects regarding concentration performance and working speed for both days. These results suggest that working posture did not affect cognitive performance in the short term.
Practitioner Summary: Prior reports indicated health-related benefits based on alternated (sit/stand) body postures. Nevertheless, their effect on cognitive performance is unknown. This randomised controlled trial showed that working in alternating body postures did not influence reaction time, concentration performance, working speed or workload perception in the short term. 相似文献