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991.
Fortunato Piersimoni Giedrius Degutis Sabine Bertho Koen Vandewal Donato Spoltore Tim Vangerven Jeroen Drijkoningen Marlies K. Van Bael An Hardy Jan D'Haen Wouter Maes Dirk Vanderzande Milos Nesladek Jean Manca 《Journal of Polymer Science.Polymer Physics》2013,51(16):1209-1214
For an increased lifetime of polymer:fullerene bulk heterojunction (BHJ) solar cells, an understanding of the chemical and morphological degradation phenomena taking place under operational conditions is crucial. Phase separation between polymer and fullerene induced by thermal stress has been pointed out as a major issue to overcome. While often the effect of thermal stress on the morphology of polymer:fullerene BHJ is investigated in the darkness, here we observe that light exposure slows down fullerene crystallization and phase separation induced at elevated temperatures. The observed photo‐stabilizing effect on active layer morphology is quite independent on the polymer and is attributed to light‐induced dimerization of the fullerene. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013 , 51, 1209–1214 相似文献
992.
Stephan Felder Dr. Sandra Dreisigacker Dr. Stefan Kehraus Edith Neu Prof. Dr. Gabriele Bierbaum Patrick R. Wright Prof. Dr. Dirk Menche Dr. Till F. Schäberle Prof. Dr. Gabriele M. König 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(28):9319-9324
Marine myxobacteria (Enhygromyxa, Plesiocystis, Pseudoenhygromyxa, Haliangium) are phylogenetically distant from their terrestrial counterparts. Salimabromide is the first natural product from the Plesiocystis/Enhygromyxa clade of obligatory marine myxobacteria. Salimabromide has a new tetracyclic carbon skeleton, comprising a brominated benzene ring, a furano lactone residue, and a cyclohexane ring, bridged by a seven‐membered cyclic moiety. The absolute configuration was deduced from experimental and calculated CD data. Salimabromide revealed antibiotic activity towards Arthrobacter cristallopoietes. 相似文献
993.
Abstract The pressure-dependence of the pericyclic rearrangements mentioned in the title uncovers a simple relation between volumes of activation and the number of new cyclic interactions in the transition state. Each new ring formed in the transition state of these pencyclic rearrangements contributes to the volume of activation by roughly ?10 to ?12 cm3mol?1. Therefore, volumes of activation provide an important information on the geometry of transition states. 相似文献
994.
Swetlana Herbrandt Uwe Ligges Manuel Pinho Ferreira Michael Kansteiner Dirk Biermann Wolfgang Tillmann Claus Weihs 《Computational Statistics》2018,33(3):1127-1143
We present a model for simulating normal forces arising during a grinding process in cement for single diamond grinding. Assuming the diamond to have the shape of a pyramid, a very fast calculation of force and removed volume can be achieved. The basic approach is the simulation of the scratch track. Its triangle profile is determined by the shape of the diamond. The approximation of the scratch track is realized by stringing together polyhedra. Their sizes depend on both the actual cutting depth and an error implicitly describing the material brittleness. Each scratch track part can be subdivided into three three-dimensional simplices for a straightforward calculation of the removed volume. Since the scratched mineral subsoil is generally inhomogeneous, the forces at different positions of the workpiece are expected to vary. This heterogeneous nature is considered by sampling from a Gaussian random field. To achieve a realistic outcome the model parameters are adjusted applying model based optimization methods. A noisy Kriging model is chosen as surrogate to approximate the deviation between modelled and observed forces. This deviation is minimized and the results of the modelled forces and the actual forces from conducted experiments are rather similar. 相似文献
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Marianne Vandenbossche Gesine Gunkel-Grabole Anja Car Laetitia Bernard Patrick Rupper Katharina Maniura-Weber Manfred Heuberger Greta Faccio Dirk Hegemann 《Plasma Chemistry and Plasma Processing》2018,38(4):851-870
Using low pressure plasma polymerization, nano-scaled oxygen-rich plasma polymer films (CO) were deposited onto pristine silicon wafers as well as on nitrogen-containing plasma polymer (CN) model surfaces. We investigate the influence of the nature of the substrate as well as a potential sub-surface effect emerging from the buried CO/CN interface, just nanometers below the surface. X-ray Photoelectron Spectroscopy and Time-of-Flight Secondary Ion Mass Spectrometry revealed two important phenomena that occurred during the deposition of the terminal CO layer: (1) a strong degree of oxidation, already for 1 nm nominal thickness, and (2) a gradual transition in chemical composition between the two layers, clearly indicating that effectively a vertical chemical gradient results, even when a two-step coating process was applied. Such terminal gradient film structures were used to study film stability in aqueous environments. Molecular rearrangements were scrutinized in the top-surface in contact with water and we found that the top-surface chemistry and wetting properties of the oxygen-rich termination layer matched those of thick CO reference coatings. Nevertheless, the adsorption of green fluorescent protein (GFP) was observed to be sensitive to the CO terminal layer thickness. Namely, an enhanced protein adsorption was observed for 1–2 nm thick CO layers on CN, whereas a significantly reduced protein adsorption was seen on ≥?3 nm thick CO terminal layers. We conclude that both, surface and sub-surface conditions significantly affect protein adsorption as opposed to the traditional consideration of surface properties alone. 相似文献
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Getting the Most out of Solar Irradiation: Efficient Use of Polychromatic Light for Water Splitting
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Ümit Taştan Dr. Dirk Ziegenbalg 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(52):18824-18832
To increase the fraction of utilizable polychromatic light, a new reactor concept was developed and manufactured by using rapid prototyping technologies. Investigation of the prototypes revealed enhancements of the photocurrent by up to one order of magnitude, when TiO2 was used as the photoanode in combination with commercially available photovoltaic cells. The reported concept is scalable and an easy transfer to technical scale is expected from a technological as well as an economical perspective. Experimental results underline the conclusion that to achieve efficient overall use of solar irradiation both the material as well as the reactor/process must be considered. Combining these complementary approaches allows largest possible optimization potential. With respect to ongoing research, the concept also breaks ground for the development of catalysts. 相似文献