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91.
T Schulz M Leibold C Färber M Maurer T Porsch MC Holthausen U Siemeling 《Chemical communications (Cambridge, England)》2012,48(73):9123-9125
The "Alder carbene" (iPr(2)N)(2)C undergoes a β-fragmentation in solution already at room temperature, affording propene and N,N,N'-triisopropylformamidine. This stands in sharp contrast to the indefinite stability previously claimed for this iconic compound. 相似文献
92.
Sandra Engelskirchen Reinhard Maurer Tatjana LevyRainer Berghaus Helmut AuweterOtto Glatter 《Journal of colloid and interface science》2012,388(1):151-161
Effective plant protection agents are readily available and well implemented in industry. However, delivery to the plant and application on the leaf are processes that still need to be optimized. Up to now plant protection formulations represent either emulsion or suspension concentrates that often contain environmentally harmful organic solvents and/or adjuvants. Emulsified microemulsions are hierarchically organized systems comprising emulsion droplets that confine a water-in-oil microemulsion. In the present contribution we show that emulsified microemulsions prepared from environmentally friendly components can be loaded with the plant-protection agent Fenpropimorph® up to 48 wt.% without organic solvent. The emulsion itself is highly concentrated, containing 60 wt.% of dispersed phase, and can be readily diluted with water for spraying in farming applications. Small-angle X-ray measurements reveal the existence of a water-in-Fenpropimorph® microemulsion confined inside the emulsion droplets. Dynamic light scattering shows that the emulsions prepared are monomodal, comprising droplet radii in the hundred nanometer range. 相似文献
93.
Markus R. Meyer Christian Vollmar Andrea E. Schwaninger Ehud Wolf Hans H. Maurer 《Journal of mass spectrometry : JMS》2012,47(2):253-262
3‐Bromomethcathinone (3‐BMC) and 3‐Fluoromethcathinone (3‐FMC) are two new designer drugs, which were seized in Israel during 2009 and had also appeared on the illicit drug market in Germany. These two compounds were sold via the Internet as so‐called “bath salts” or “plant feeders.” The aim of the present study was to identify for the first time the 3‐BMC and 3‐FMC Phase I and II metabolites in rat urine and human liver microsomes using GC–MS and LC–high‐resolution MS (HR‐MS) and to test for their detectability by established urine screening approaches using GC–MS or LC–MS. Furthermore, the human cytochrome‐P450 (CYP) isoenzymes responsible for the main metabolic steps were studied to highlight possible risks of consumption due to drug–drug interaction or genetic variations. For the first aim, rat urine samples were extracted after and without enzymatic cleavage of conjugates. The metabolites were separated and identified by GC–MS and by LC–HR‐MS. The main metabolic steps were N‐demethylation, reduction of the keto group to the corresponding alcohol, hydroxylation of the aromatic system and combinations of these steps. The elemental composition of the metabolites identified by GC–MS could be confirmed by LC–HR‐MS. Furthermore, corresponding Phase II metabolites were identified using the LC–HR‐MS approach. For both compounds, detection in rat urine was possible within the authors' systematic toxicological analysis using both GC–MS and LC–MSn after a suspected recreational users dose. Following CYP enzyme kinetic studies, CYP2B6 was the most relevant enzyme for both the N‐demethylation of 3‐BMC and 3‐FMC after in vitro–in vivo extrapolation. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
94.
The optimal control of an industrial robot is considered as a parametricnonlinear control problem subject to control and state constraints. Based onrecent stability results for parametric control problems, a robust nonlinearprogramming method is proposed to compute the sensitivity of open-loopcontrol solutions. Real-time control approximations of the perturbedoptimal solutions are obtained by evaluating first-order Taylor expansionsof the optimal solutions with respect to the parameter. The proposednumerical methods are applied to the industrial robot Manutec r3. Thequality of the real-time approximations is illustrated for perturbations inthe transport load. 相似文献
95.
Tetsuya Hirade Frans H. J. Maurer Morten Eldrup 《Radiation Physics and Chemistry》2000,58(5-6):465-471
Measurements have been carried out of electron spin densities (by electron spin resonance technique) and positronium (Ps) formation probability as functions of Co-60 γ-irradiation dose in poly(methyl methacrylate) and linear poly(ethylene) at 77 K. We observe a linear relationship between the enhancement of the Ps formation and the density of trapped electrons in both polymers. This clear correlation strongly supports the previous suggestion by the authors that the increase in Ps formation with time (that has been observed at low temperatures for a number of polymers) can be explained as a reaction of free positrons with trapped electrons produced by the previously injected positrons. 相似文献
96.
Unique information about the properties of free-volume sites in polymers is gained from Positron Annihilation Lifetime (PAL) measurements. After calibration with data from other techniques the method may be used to determine free-volume fractions. From pressure–volume–temperature (PVT) and PAL (ortho-Ps lifetime τ3) data, measured on identical amorphous poly(methyl methacrylate) (PMMA) samples with controlled thermal histories, we find a linear relationship between free-volume fractions, derived from PVT measurements, the Simha–Somcynsky equation-of-state theory and the mean subnanometer free-volume size both below and above the glass transition temperature. 相似文献
97.
Parametric nonlinear optimal control problems subject to control and state constraints are studied. Two discretization methods are discussed that transcribe optimal control problems into nonlinear programming problems for which SQP-methods provide efficient solution methods. It is shown that SQP-methods can be used also for a check of second-order sufficient conditions and for a postoptimal calculation of adjoint variables. In addition, SQP-methods lead to a robust computation of sensitivity differentials of optimal solutions with respect to perturbation parameters. Numerical sensitivity analysis is the basis for real-time control approximations of perturbed solutions which are obtained by evaluating a first-order Taylor expansion with respect to the parameter. The proposed numerical methods are illustrated by the optimal control of a low-thrust satellite transfer to geosynchronous orbit and a complex control problem from aquanautics. The examples illustrate the robustness, accuracy and efficiency of the proposed numerical algorithms. 相似文献
98.
We study optimal control problems for semilinear elliptic equations subject to control and state inequality constraints. In a first part we consider boundary control problems with either Dirichlet or Neumann conditions. By introducing suitable discretization schemes, the control problem is transcribed into a nonlinear programming problem. It is shown that a recently developed interior point method is able to solve these problems even for high discretizations. Several numerical examples with Dirichlet and Neumann boundary conditions are provided that illustrate the performance of the algorithm for different types of controls including bang-bang and singular controls. The necessary conditions of optimality are checked numerically in the presence of active control and state constraints. 相似文献
99.
W. Maurer G. Schaldach W. Wagener und J. Peters 《Fresenius' Journal of Analytical Chemistry》1985,322(3):359-364
Zusammenfassung Die Metallgehalte von Coniferennadeln (Ca, Mg, Zn, Pb, Fe, Mn, Cu, Na, K) lassen sich nach einem Königswasseraufschluß mit Hilfe der Flammen-AAS bzw. der Flammenemission bestimmen. Um repräsentative Ergebnisse jüngerer (20–30 Jahre alter) Waldbestände zu erhalten, wurden die Probenahmebedingungen systematisch variiert. Es zeigte sich, daß bezüglich der jeweiligen Meßgröße neben dem Nadeljahrgang insbesondere die Höhe des Astes über Grund, von dem die Nadeln stammen, die Astrichtung (bezogen auf die Richtung des mittleren Wettereinflusses), aber auch sehr individuelle Faktoren wie Abschattung oder freier Lichteinfall auf den betreffenden Ast, eine Rolle spielen.
Herrn Prof. Dr. H. Monien zum 60. Geburtstag gewidmet 相似文献
Determination of essential and toxic cations in needles of conifersProblems of representative sample collection
Summary The metal contents of conifer needles (Ca, Mg, Zn, Pb, Fe, Mn, Cu, Na, K) are determined after digestion with aqua regia using atomic absorption by flame emission spectroscopy. In order to obtain representative data for certain forest sites (20–30 year old trees) sample collection programs were varied systematically. It can be shown that the following parameters are of great influence on the observed element concentrations: the age of the needles, the height of the branch from the butt, the direction of the branch due to the direction of the mean weather influence but also local individual factors such as hindered or free light throughfall on the branch from which the needles are taken.
Herrn Prof. Dr. H. Monien zum 60. Geburtstag gewidmet 相似文献
100.