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排序方式: 共有131条查询结果,搜索用时 125 毫秒
31.
Elisabeth Kreutzwiesner Nadja Noormofidi Frank Wiesbrock Wolfgang Kern Karl Rametsteiner Franz Stelzer Christian Slugovc 《Journal of polymer science. Part A, Polymer chemistry》2010,48(20):4504-4514
This study is aimed at investigating the microbiocidal potential of amino‐functionalized poly(norbornenes) in the solid state. A series of norbornene‐type monomers that carry secondary or tertiary amine functions as well as hexyl and dodecyl groups were prepared. Ring‐opening metathesis polymerization was used to prepare homopolymers of the amine bearing monomers and random copolymers of amine‐ and alkyl‐substituted monomers of high average molar mass. The resulting polymers were characterized by nuclear magnetic resonance, thermogravimetry, differential scanning calorimetry, infrared spectroscopy, and contact angle measurements, and their contact biocidal potential was evaluated according to the Japanese Industry standard Z2801. Tested microorganisms comprised Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Candida albicans, and Aspergillus niger. Microbiocidal activity of selected polymer films against E. coli, S. aureus, and A. niger was found, whereas against C. albicans and P. aeruginosa microbiostatic behavior was observed. Moreover, the most potent copolymer revealed no cytotoxicity rendering a biocidal polymer with potential applications in mammalian‐, and in particular, human‐related fields. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010 相似文献
32.
Patrick Michaelis Nadja Klein Thomas Kneib 《Journal of computational and graphical statistics》2018,27(3):602-611
The normal and the t distribution are classical tools for building random effects regression models where both can be used for the specification of either the conditional response distribution or the random effects distribution. However, the underlying assumption of symmetry can be questionable in many applications. We, therefore, propose regression models where the skew-normal and skew-t distribution are considered for both the response and the random effects specification and embed these models in the framework of distributional regression such that regression predictors can be specified for all distributional parameters. The distributional regression framework also allows us to consider multivariate versions of the skew-normal and the skew-t distribution. For Bayesian inference, we adapt iteratively weighted least-square proposals within Markov chain Monte Carlo simulations such that they can also facilitate the inclusion of nonnormal random effects specifications. Model choice is based on the Watanabe–Akaike information criterion, in particular, to differentiate between skew and nonskew distributional specifications in a number of simulation studies. Finally, to illustrate their practical applicability, the developed models are applied to a study on cholesterol levels originating from the Framingham Heart Study and a dataset from the Demographic and Health Surveys on undernutrition among children in Nigeria. Supplementary material for this article is available online. 相似文献
33.
Thorben Cordes Björn Heinz Nadja Regner Christian Hoppmann Tobias E. Schrader Wolfram Summerer Karola Rück‐Braun Prof. Dr. Wolfgang Zinth Prof. Dr. 《Chemphyschem》2007,8(11):1713-1721
The molecule HTI, which combines hemithioindigo and hemistilbene molecular parts, allows reversible switching between two isomeric states. Photochromic behaviour of the HTI molecule is observed by irradiation with UV/Vis light. The photochemical reaction, a Z/E isomerization around the central double bond connecting the two molecular parts, is investigated by transient absorption and emission spectroscopy. For a special HTI molecule, namely, an omega-amino acid, the Z-->E isomerization process occurs on a timescale of 30 ps. In the course of the reaction fast processes on the 1-10 ps timescale are observed which point to motions of the molecule on the potential-energy surface of the excited state. The combination of transient absorption experiments in the visible spectral range with time-resolved fluorescence and infrared measurements reveal a photochemical pathway with three intermediate states. Together with a theoretical modelling procedure the experiments point to a sequential reaction scheme and give indications of the nature of the involved intermediates. 相似文献
34.
Nadja Schultz-Jensen Frank Leipold Henrik Bindslev Anne Belinda Thomsen 《Applied biochemistry and biotechnology》2011,163(4):558-572
O3 generated in a plasma at atmospheric pressure and room temperature, fed with dried air (or oxygen-enriched dried air), has
been used for the degradation of lignin in wheat straw to optimize the enzymatic hydrolysis and to get more fermentable sugars.
A fixed bed reactor was used combined with a CO2 detector and an online technique for O3 measurement in the fed and exhaust gas allowing continuous measurement of the consumption of O3. This rendered it possible for us to determine the progress of the pretreatment in real time (online analysis). The process
time can be adjusted to produce wheat straw with desired lignin content because of the online analysis. The O3 consumption of wheat straw and its polymeric components, i.e., cellulose, hemicellulose, and lignin, as well as a mixture
of these, dry as well as with 50% water, were studied. Furthermore, the process parameters dry matter content and milled particle
size (the extent to which the wheat straw was milled) were investigated and optimized. The developed methodology offered the
advantage of a simple and relatively fast (0.5–2 h) pretreatment allowing a dry matter concentration of 45–60%. FTIR measurements
did not suggest any structural effects on cellulose and hemicellulose by the O3 treatment. The cost and the energy consumption for lignin degradation of 100 g of wheat straw were calculated. 相似文献
35.
36.
Nadja Harms Tim Hoheisel Christian Kanzow 《Journal of Optimization Theory and Applications》2014,163(2):413-438
A well-known technique for the solution of quasi-variational inequalities (QVIs) consists in the reformulation of this problem as a constrained or unconstrained optimization problem by means of so-called gap functions. In contrast to standard variational inequalities, however, these gap functions turn out to be nonsmooth in general. Here, it is shown that one can obtain an unconstrained optimization reformulation of a class of QVIs with affine operator by using a continuously differentiable dual gap function. This extends an idea from Dietrich (J. Math. Anal. Appl. 235:380–393 [24]). Some numerical results illustrate the practical behavior of this dual gap function approach. 相似文献
37.
Shuaijun Pan Rui Guo Nadja Bertleff‐Zieschang Shanshan Li Quinn A. Besford Qi‐Zhi Zhong Gyeongwon Yun Yunti Zhang Francesca Cavalieri Yi Ju Eirini Goudeli Joseph J. Richardson Frank Caruso 《Angewandte Chemie (International ed. in English)》2020,59(1):275-280
The manipulation of interfacial properties has broad implications for the development of high‐performance coatings. Metal–phenolic networks (MPNs) are an emerging class of responsive, adherent materials. Herein, host–guest chemistry is integrated with MPNs to modulate their surface chemistry and interfacial properties. Macrocyclic cyclodextrins (host) are conjugated to catechol or galloyl groups and subsequently used as components for the assembly of functional MPNs. The assembled cyclodextrin‐based MPNs are highly permeable (even to high molecular weight polymers: 250–500 kDa), yet they specifically and noncovalently interact with various functional guests (including small molecules, polymers, and carbon nanomaterials), allowing for modular and reversible control over interfacial properties. Specifically, by using either hydrophobic or hydrophilic guest molecules, the wettability of the MPNs can be readily tuned between superrepellency (>150°) and superwetting (ca. 0°). 相似文献
38.
New In Situ Trapping Metalations of Functionalized Arenes and Heteroarenes with TMPLi in the Presence of ZnCl2 and Other Metal Salts
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M. Sc. Annette Frischmuth Dr. Maitane Fernández M. Sc. Nadja M. Barl M. Sc. Florian Achrainer Prof. Dr. Hendrik Zipse Dr. Guillaume Berionni Prof. Dr. Herbert Mayr Prof. Dr. Konstantin Karaghiosoff Prof. Dr. Paul Knochel 《Angewandte Chemie (International ed. in English)》2014,53(30):7928-7932
The addition of TMPLi to a mixture of an aromatic or heteroaromatic substrate with a metal salt such as MgCl2, ZnCl2, or CuCN at ?78 °C first leads to lithiation of the arene followed by transmetalation with the metal salt to afford functionalized organometallic compounds of Mg, Zn, or Cu. This in situ trapping method allows an expedited metalation (?78 °C, 5 min) of a range of sensitive pyridines (bearing a nitro, ester, or cyano group) and allows the preparation of kinetic regioisomers of functionalized aromatic compounds or heterocycles not otherwise available by standard metalating agents, such as TMPMgCl?LiCl or TMPZnCl?LiCl. 相似文献
39.
We propose a simple and effective heuristic to save memory in dynamic programming on tree decompositions when solving graph optimization problems. The introduced “anchor technique” is based on a tree-like set covering problem. We substantiate our findings by experimental results. Our strategy has negligible computational overhead concerning running time but achieves memory savings for nice tree decompositions and path decompositions between 60% and 98%. 相似文献
40.
Nadja S. Magalhães Odylio D. Aguiar Warren W. Johnson Carlos Frajuca 《General Relativity and Gravitation》1997,29(12):1511-1525
We solve algebraically the equations of motion for a spherical antenna coupled to an arbitrary number of small resonators, free to move radially, and investigate the conditions under which damping forces can be neglected in the system. We show that in order that the antenna's modes be decoupled a preferred distribution of the resonators on its surface should be used. We find that either 5, 6, 10 or 16 resonators can be used as long as they are conveniently positioned on the antenna's surface. We calculate and analyse the frequency shift and the signal-to-noise ratio of the coupled system for the various distributions studied. 相似文献