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排序方式: 共有638条查询结果,搜索用时 9 毫秒
81.
Silvia Moreno Priyanka Sharan Johanna Engelke Hannes Gumz Susanne Boye Ulrich Oertel Peng Wang Susanta Banerjee Rafal Klajn Brigitte Voit Albena Lederer Dietmar Appelhans 《Small (Weinheim an der Bergstrasse, Germany)》2020,16(37)
Temporal activation of biological processes by visible light and subsequent return to an inactive state in the absence of light is an essential characteristic of photoreceptor cells. Inspired by these phenomena, light‐responsive materials are very attractive due to the high spatiotemporal control of light irradiation, with light being able to precisely orchestrate processes repeatedly over many cycles. Herein, it is reported that light‐driven proton transfer triggered by a merocyanine‐based photoacid can be used to modulate the permeability of pH‐responsive polymersomes through cyclic, temporally controlled protonation and deprotonation of the polymersome membrane. The membranes can undergo repeated light‐driven swelling–contraction cycles without losing functional effectiveness. When applied to enzyme loaded‐nanoreactors, this membrane responsiveness is used for the reversible control of enzymatic reactions. This combination of the merocyanine‐based photoacid and pH‐switchable nanoreactors results in rapidly responding and versatile supramolecular systems successfully used to switch enzymatic reactions ON and OFF on demand. 相似文献
82.
83.
Muhammad Izhar Kairi Mehrnoush Khavarian Suriani Abu Bakar Brigitte Vigolo Abdul Rahman Mohamed 《Journal of Materials Science》2018,53(2):851-879
Graphene is a single layer of carbon atoms arranged in an sp2-hybridized structure with properties far superior compared to other materials. Research and development in graphene synthesis have been rapidly growing the past few years, especially using chemical vapor deposition (CVD) over various types of carbon precursor. The nature and the type of carbon precursor is one important parameter of growth by CVD, especially for graphene production, since they can dramatically impact graphene growth yield and rate. However, effects of the used carbon precursor on graphene growth mechanisms are rarely discussed. In the course of large-scale and low-cost graphene preparation, this review on the recent trends regarding the utilization of diverse carbon precursors used to synthesize graphene via the CVD method is of great interest for development of improved or alternative synthesis methods. The details and the mechanisms involved in graphene synthesis using carbon precursors in the form of gaseous, liquids and solids are compared, analyzed and discussed thoroughly. In this review, we present a thorough overview on the impact and mechanisms of carbon precursors in achieving high-quality graphene with competitive edge in the near future. 相似文献
84.
Vincenzo Farano Mark Cresswell Kerstin Gritsch Phil Jackson Nina Attik Brigitte Grosgogeat Jean-Christophe Maurin 《Journal of materials science. Materials in medicine》2018,29(7):101
Phosphate-based glasses have been attracting attention due to their possible medical applications arising from unique dissolution characteristics in the human body leading to the possibility of new tissue regeneration. In this study, the leaching kinetics of a series of melt-quenched Sr-doped phosphate glasses are presented. Regardless of the presence of Sr, all the glasses have an initial linear and sustained release of the ions followed by a plateau. To guarantee proper nutritional support to the growing tissue during regeneration and to mimic the 3-dimensional architecture of tissues, organic scaffold systems have been developed. However, their poor mechanical strength has limited their application. To overcome this problem, cross-linkers can be used although this then limits the solubility of the materials. To succeed in dealing with such a limitation, in this paper, by freeze-drying, the aforementioned soluble melt-quenched phosphate glasses were combined as powders with collagen fibres from bovine achilles tendon to make degradable scaffolds. The scaffolds were characterized by SEM, EDX and BET. Changes to the dissolution behaviour of the glasses arising from the presence of collagen interacting with the ions leached were reported. Furthermore, the ability of the scaffolds to induce hydroxyapatite (HA) formation was evaluated: one the elaborated scaffold could grow an HA-like layer after a week in SBF. Based on the results obtained, a possible application in restorative dentistry is proposed for one or more materials. 相似文献
85.
回顾我国水污染补偿的研究及实践,分析潘家口—大黑汀水源地及入库河流的水质状况,在明确考核断面及考核指标的基础上,建立基于污染物通量的水污染补偿量化估算模型,并根据2013年潘家口—大黑汀水源地入库河流的水质和水量监测数据,估算入库河流水污染生态补偿量。 相似文献
86.
Marco Sangermano Anna Di Gianni Roberta Bongiovanni Aldo Priola Brigitte Voit Doris Pospiech Dietmar Appelhans 《大分子材料与工程》2005,290(7):721-725
Summary: A fluorine containing hyperbranched polymer was synthesized by modifying an aromatic‐aliphatic hyperbranched polyester with a semifluorinated alcohol via a Mitsunobu reaction and was subsequently used as an additive in cationic photopolymerization of an epoxy resin. The remaining OH groups of the fluorinated hyperbranched polymer interact with the polymeric carbocation through a chain‐transfer mechanism inducing an increase in the final epoxy conversion. The fluorinated HBP induces modification of bulk and surface properties, with an increase in Tg and surface hydrophobicity already reached at very low concentration. The HBFP additive can, therefore, protect the coatings from aggressive solvents, increases hardness, and allows the preparation of a low energy surface coating.
87.
Implant Materials: Assessment of Novel Long‐Lasting Ceria‐Stabilized Zirconia‐Based Ceramics with Different Surface Topographies as Implant Materials (Adv. Funct. Mater. 40/2017) 下载免费PDF全文
88.
Karel Friess Alexander Sagidullin Brigitte Wiesner Jochen Meier-Haack Ulrich Scheler 《Polymer Science Series C》2017,59(1):102-105
Free-standing polyelectrolyte multilayer membranes have been formed by the layer-by-layer technique using a dip-coating apparatus. The polymer-chain mobility has been studied by 1H relaxation in the rotating frame T 1rho NMR with 13C chemical shift resolution. For each of the individual polymers a single relaxation component has been observed for all resolved signals. In the multilayer a significantly different relaxation time T 1rho has been observed with a minor second component. The interaction between the oppositely charged polyelectrolytes influences the molecular mobility. 相似文献
89.
Assessing changes in the isotopic signature of contaminants is a promising new tool to monitor microbial degradation processes. In this study, chloroethene degradation was proven by depletion of chloroethenes, formation of chloride, increase in protein content and stable carbon isotope fractionation. Aerobic degradation of vinyl chloride (VC) was found to proceed metabolically, with degradation rates of 0.48 and 0.29 d(-1); and growth yields of 9.7 and 6.4 g of protein/mol of VC at room and groundwater temperature, respectively. Cis-1,2-dichloroethene (cDCE) was degraded cometabolically under aerobic conditions when VC was provided as growth substrate. Aerobic degradation was associated with significant stable carbon isotope fractionation, with enrichment factors ranging from -5.4+/-0.4 per thousand for metabolic degradation of VC to -9.8+/-1.7 per thousand for cometabolic degradation of cDCE. Thus, it was demonstrated that stable carbon isotope fractionation is suitable for assessing aerobic chloroethene degradation, which can contribute significantly to site remediation. 相似文献
90.
Liu L Diaz F Wang L Loiseaux B Huignard JP Sheppard CJ Chen N 《Journal of the Optical Society of America. A, Optics, image science, and vision》2008,25(8):2095-2101
In the paraxial Debye regime, simple and power-efficient pupil filters are designed to break the diffraction limit along a large depth of focus (DOF) for the Gaussian beam. Dependences of the superresolution factor, DOF gain, Strehl ratio, sidelobe strength, and axial intensity nonuniformity on the Gaussian profile in the pupil plane are characterized using the numerical method. Optimal filter designs are proposed for either high-resolution or ultra-large-DOF applications followed by experimental verifications. 相似文献