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排序方式: 共有443条查询结果,搜索用时 15 毫秒
1.
Hélène Beucher Dr. Sudhir Kumar Dr. Roopender Kumar Dr. Estíbaliz Merino Wei-Hsu Hu Gerrit Stemmler Sergio Cuesta-Galisteo Dr. Jorge A. González Léonard Bezinge Dr. Jakub Jagielski Dr. Chih-Jen Shih Prof. Dr. Cristina Nevado 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(72):17604-17612
Efficient OLED devices have been fabricated using organometallic complexes of platinum group metals. Still, the high material cost and low stability represent central challenges for their application in commercial display technologies. Based on its innate stability, gold(III) complexes are emerging as promising candidates for high-performance OLEDs. Here, a series of alkynyl-, N-heterocyclic carbene (NHC)- and aryl-gold(III) complexes stabilized by a κ3-(N^C^C) template have been prepared and their photophysical properties have been characterized in detail. These compounds exhibit good photoluminescence quantum efficiency (ηPL) of up to 33 %. The PL emission can be tuned from sky-blue to yellowish green colors by variations on both the ancillary ligands as well as on the pincer template. Further, solution-processable OLED devices based on some of these complexes display remarkable emissive properties (ηCE 46.6 cd.A−1 and ηext 14.0 %), thus showcasing the potential of these motifs for the low-cost fabrication of display and illumination technologies. 相似文献
2.
Lien Vermeir Arnout Declerck Chak Ming To Barbara Kerkaert Paul Van der Meeren 《Magnetic resonance in chemistry : MRC》2019,57(9):674-685
A time-domain 1H nuclear magnetic resonance relaxometry method was elaborated for the rapid microstructural characterization of mozzarella cheese. For this purpose, there is a strong need to know how the experimentally determined T2 relaxation time distribution can be related to specific constituents in mozzarella. In this study, a detailed investigation is offered for fresh and aged low-moisture mozzarella cheese, often applied as a pizza cheese, by application of both a conventional Carr–Purcell–Meiboom–Gill (CPMG) sequence and a free-induction decay CPMG (FID-CPMG) sequence. The relaxation behavior was further elucidated by addition of deuterium oxide and by mild heat treatment of samples. The relaxation times of water protons in mozzarella were found to range from a few microseconds to some tens of milliseconds (in aged mozzarella) or to about hundred milliseconds (in fresh mozzarella). The upper limit of the T2 distribution can even be extended to the seconds range upon releasing water protons from the mozzarella matrix using a mild heat treatment or upon addition of deuterated water. Both stimuli also provided evidence for the absorption of water into the cheese matrix. The potential release and uptake of water demonstrated that mozzarella acts as a very dynamic system during production and storage. The detected differences in the behavior of the water fraction between fresh and aged low-moisture mozzarella might be utilized to study the influence of either production and/or storage conditions on the cheese ripening process. 相似文献
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Vincent S. D. Voet Gerrit ten Brinke Katja Loos 《Journal of polymer science. Part A, Polymer chemistry》2014,52(20):2861-2877
Poly(vinylidene fluoride) (PVDF) has reached the second largest production volume of fluoropolymers in recent years, and its popularity can be ascribed to high thermal stability and chemical inertness combined with its ferroelectric behavior. Copolymerization of vinylidene fluoride with other monomers leads to a wide variety of products with modified or improved properties. Besides commercially available fluorinated random copolymers, well‐defined block‐, graft, and alternating copolymers based on PVDF received more attention in recent years. PVDF‐containing block copolymers that may self‐assemble into well‐ordered morphologies are of particular interest, being potential precursors for functional nanostructured materials applicable in membranes and electronics. This Highlight provides an overview of the routes developed towards these materials via conventional and controlled polymerization techniques. In addition, it discusses their nanoscopic phase behavior and current and potential applications. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2861–2877 相似文献
5.
Derk Balthazar de Graaf Yawar AbbasJohan Gerrit Bomer Wouter OlthuisAlbert van den Berg 《Analytica chimica acta》2015
Chloride is a crucial anion for various analytical applications from biological to environmental applications. In order to measure the chloride ion concentration, a measurement system is needed which can detect this concentration for prolonged times reliably. Chronopotentiometry is a technique which does not need a long term stable reference electrode and is therefore very suitable for prolonged ion concentration measurements. As the used electrode might be fouled by reaction products, this work focuses on a chronopotentiometric approach with a separated sensing electrode (sensor) and actuating electrode (actuator). Both actuation and sensor electrode are made of Ag/AgCl. A constant current is applied to the actuator and will start the reaction between Ag and Clˉ, while the resulting Clˉ ion concentration change is observed through the sensor, which is placed close to the actuator. The time it takes to locally deplete the Clˉ ions is called transition time. Experiments were performed to verify the feasibility of this approach. The performed experiments show that the sensor detects the local concentration changes resulting from the current applied to the actuator. A linear relation between the Clˉ ion concentration and the square root of the transition time was observed, just as was predicted by theory. The calibration curves for different chips showed that both a larger sensor and a larger distance between sensor and actuator resulted in a larger time delay between the transition time detected at the actuator and the sensor. 相似文献
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Martin Faber Anton H. Hofman Katja Loos Gerrit ten Brinke 《Macromolecular rapid communications》2016,37(11):911-919
Linear poly(4‐tert‐butoxystyrene)‐b‐poly(4‐vinylpyridine) (PtBOS‐b‐P4VP) diblock copolymers are synthesized using reversible addition–fragmentation chain transfer polymerization. The self‐assembly of four different PtBOS‐b‐P4VP diblock copolymers is studied using small‐angle X‐ray scattering and transmission electron microscopy and a number of interesting observations are made. A tBOS62‐b‐4VP28 diblock copolymer with a weight fraction P4VP of 0.21 shows a disordered morphology of P4VP spheres with liquid‐like short‐range order despite an estimated value of of the order of 50. Increasing the length of the 4VP block to tBOS62‐b‐4VP199 results in a diblock copolymer with a weight fraction P4VP of 0.66. It forms a remarkably well‐ordered lamellar structure. Likewise, a tBOS146‐b‐4VP120 diblock copolymer with a weight fraction P4VP of 0.33 forms an extremely well‐ordered hexagonal structure of P4VP cylinders. Increasing the P4VP block of this block copolymer to tBOS146‐b‐4VP190 with a weight fraction P4VP of 0.44 results in a bicontinuous gyroid morphology despite the estimated strong segregation of . These results are discussed in terms of the architectural dissimilarity of the two monomers, characterized by the presence of the large side group of PtBOS, and the previously reported value of the interaction parameter, , for this polymer pair.
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9.
Peter C. Roozemond Martin van Drongelen Zhe Ma Anne B. Spoelstra Daniel Hermida‐Merino Gerrit W. M. Peters 《Macromolecular rapid communications》2015,36(4):385-390
Flow‐induced structure formation is investigated with in situ wide‐angle X‐ray diffraction with high acquisition rate (30 Hz) using isotactic polypropylene in a piston‐driven slit flow with high wall shear rates (up to ≈900 s−1). We focus on crystallization within the shear layers that form in the high shear rate regions near the walls. Remarkably, the kinetics of the crystallization process show no dependence on either flow rate or flow time; the crystallization progresses identically regardless. Stronger or longer flows only increase the thickness of the layers. A conceptual model is proposed to explain the phenomenon. Above a certain threshold, the number of shish‐kebabs formed affects the rheology such that further structure formation is halted. The critical amount is reached already within 0.1 s under the current flow conditions. The change in rheology is hypothesized to be a consequence of the “hairy” nature of shish. Our results have large implications for process modelling, since they suggest that for injection molding type flows, crystallization kinetics can be considered independent of deformation history.
10.
Vincent S. D. Voet Kamlesh Kumar Gerrit ten Brinke Katja Loos 《Macromolecular rapid communications》2015,36(19):1756-1760
The unique mechanical performance of nacre, the pearly internal layer of shells, is highly dependent on its complex morphology. Inspired by the structure of nacre, the fabrication of well‐ordered layered inorganic–organic nanohybrids is presented herein. This biomimetic approach includes the use of a block copolymer template, consisting of hydrophobic poly(vinylidene fluoride) (PVDF) lamellae covered with hydrophilic poly(methacrylic acid) (PMAA), to direct silica (SiO2) mineralization. The resulting PVDF/PMAA/SiO2 nanohybrid material resembles biogenic nacre with respect to its well‐ordered and layered nanostructure, alternating organic–inorganic phases, macromolecular template, and mild processing conditions.