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41.
Dorothea Bahns Katarzyna Rejzner Jochen Zahn 《Communications in Mathematical Physics》2014,327(3):779-814
We show that the Nambu–Goto string, and its higher dimensional generalizations, can be quantized, in the sense of an effective theory, in any dimension of the target space. The crucial point is to consider expansions around classical string configurations. We are using tools from perturbative algebraic quantum field theory, quantum field theory on curved spacetimes, and the Batalin–Vilkovisky formalism. Our model has some similarities with the Lüscher–Weisz string, but we allow for arbitrary classical background string configurations and keep the diffeomorphism invariance. 相似文献
42.
Jian Liu Mariavittoria Craighero Vandna K. Gupta Dorothea Scheunemann Sri Harish Kumar Paleti Emmy Järsvall Youngseok Kim Kai Xu Juan Sebastián Reparaz L. Jan Anton Koster Mariano Campoy-Quiles Martijn Kemerink Anna Martinelli Christian Müller 《Advanced functional materials》2024,34(18):2312549
Functionally graded materials (FGMs) are widely explored in the context of inorganic thermoelectrics, but not yet in organic thermoelectrics. Here, the impact of doping gradients on the thermoelectric properties of a chemically doped conjugated polymer is studied. The in-plane drift of counterions in moderate electric fields is used to create lateral doping gradients in films composed of a polythiophene with oligoether side chains, doped with 2,3,5,6-tetrafluoro-tetracyanoquinodimethane (F4TCNQ). Raman microscopy reveals that a bias voltage of as little as 5 V across a 50 µm wide channel is sufficient to trigger counterion drift, resulting in doping gradients. The effective electrical conductivity of the graded channel decreases with bias voltage, while an overall increase in Seebeck coefficient is observed, yielding an up to eight-fold enhancement in power factor. Kinetic Monte Carlo simulations of graded films explain the increase in power factor in terms of a roll-off of the Seebeck coefficient at high electrical conductivities in combination with a mobility decay due to increased Coulomb scattering at high dopant concentrations. Therefore, the FGM concept is found to be a way to improve the thermoelectric performance of not yet optimally doped organic semiconductors, which may ease the screening of new materials as well as the fabrication of devices. 相似文献
43.
Dorothea Wagner 《Order》1990,6(4):335-350
A decomposition theory for partial orders which arises from the split decomposition of submodular functions is introduced. As a consequence of this theory, any partial order has a unique decomposition consisting of indecomposable partial orders and certain highly decomposable partial orders. The highly decomposable partial orders are completely characterized. As a special case of partial orders, we consider lattices and distributive lattices. It occurs, that the highly decomposable distributive lattices are precisely the Boolean lattices. 相似文献
44.
Studies are described on the metabolism and the toxicological analysis of the amphetamine-derived designer drug 4-chloro-2,5-dimethoxyamphetamine
(DOC) in rat urine using gas chromatographic-mass spectrometric techniques. The metabolites identified indicated that DOC
was metabolized by O-demethylation at position 2 or 5 of the phenyl ring partly followed by glucuronidation and/or sulfation. The authors’ systematic
toxicological analysis procedure using full-scan gas chromatography-mass spectrometry after acid hydrolysis, liquid-liquid
extraction and microwave-assisted acetylation allowed the detection of an intake of a dose of DOC in rat urine that corresponds
to a common drug user’s dose. Assuming similar metabolism, the STA procedure described should be suitable as proof of an intake
of DOC in human urine. 相似文献
45.
John H. Conway Prof. Dorothea Fiedler 《Angewandte Chemie (International ed. in English)》2015,54(13):3941-3945
A resin‐bound dinuclear zinc(II) complex for the selective capture of pyrophosphopeptides is reported. The metal complex binds diphosphate esters over other anionic groups, such as monophosphate esters, sulfate esters, and carboxylic acids, with high specificity. Immobilization of the compound provided a reagent capable of binding and retaining nanomolar quantities of pyrophosphopeptide in the presence of cell lysate. The high affinity and specificity of the reagent makes it an attractive tool for the study of in vivo pyrophosphorylation. 相似文献
46.
Diana I. S. Kolberg Dorothea Mack Michelangelo Anastassiades Michael T. Hetmanski Richard J. Fussell Thijs Meijer Hans G. J. Mol 《Analytical and bioanalytical chemistry》2012,404(8):2465-2474
A new sensitive, fast and robust method for the determination of paraquat and diquat residues in potatoes, cereals and pulses is presented. Different extraction conditions (solvent, time and temperature) have been evaluated using barley grain, potatoes and dry lentils containing incurred residues of diquat and paraquat. The finalised procedure involves extraction with a mixture of methanol/water/hydrochloric acid at 80?°C and analysis by liquid chromatography–tandem mass spectrometry. Diquat D4 and Paraquat D6 internal standards were added to the test portions prior to extraction. A small-scale inter-laboratory validation of the developed method for diquat and paraquat using potato and barley samples was conducted by three laboratories. The precision and accuracy of the method were determined from recovery experiments (five replicates) at 0.01 and 0.1?mg?kg?1. The recoveries obtained (n?=?180) were in the range of 92–120?% with associated relative standard deviation (RSD) between 1.4–10?% for all compound/commodity/spiking concentration combinations. 相似文献
47.
Dorothea Diers Martin Eling Sebastian D. Marek 《Insurance: Mathematics and Economics》2012,50(3):430-436
This paper illustrates the modeling of dependence structures of non-life insurance risks using the Bernstein copula. We conduct a goodness-of-fit analysis and compare the Bernstein copula with other widely used copulas. Then, we illustrate the use of the Bernstein copula in a value-at-risk and tail-value-at-risk simulation study. For both analyses we utilize German claims data on storm, flood, and water damage insurance for calibration. Our results highlight the advantages of the Bernstein copula, including its flexibility in mapping inhomogeneous dependence structures and its easy use in a simulation context due to its representation as mixture of independent Beta densities. Practitioners and regulators working toward appropriate modeling of dependences in a risk management and solvency context can benefit from our results. 相似文献
48.
Th. Fellenberg Dorothea Herrmann Ch. Valencien J. Deshusses M. D. Florentin und Pannwitz 《Fresenius' Journal of Analytical Chemistry》1939,117(3-4):151-154
Ohne Zusammenfassung 相似文献
49.
50.
Alkylation of ferrocene bis-imines Fc[N=C(H)Ar]2 (Ar = Ph, p-Tol) with MeLi was found to proceed in a highly diastereoselective fashion producing the C2-symmetric ferrocene diamines Fc[NC(H)(Me)Ar]2-H2 with 90% diastereomeric excess. This process allowed for the synthesis of C2-symmetric zirconium complexes Fc[NC(Me)Ar]ZrBn2. 相似文献