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41.
A model for the distribution of cations in the spinel lattice of manganese ferrites MnFe2O4+
was elaborated on the basis of the experimental studies of the basic magnetic quantities, electrical conductivity and magnetic relaxation of the given ferrites, taking into consideration their crystallographic properties. The conclusions following from this model are in good agreement with the experimental results obtained by us and by other authors both for stoichiometric manganese ferrite and for a ferrite where 0.
I. MnFe2O4+
, MnFe2O4+ . , , , , , 0.相似文献
42.
43.
Karel Hamal 《Czechoslovak Journal of Physics》1968,18(3):419-422
A solid state laser has been developed which employs a spherical pumping cavity. The rod of the active medium (ruby, neodymium, etc.) and the flash tube are symmetrically placed with respect to a plane passing through the centre of the sphere. With Nd3+-doped glass an efficiency of 3% is obtained. 相似文献
44.
Marina Davydova Alexander Kromka Oleg Babchenko Karel Hruska 《Applied Surface Science》2010,256(18):5602-1312
Diamond nanorods were fabricated for a sensing device by utilizing reactive ion etching in CF4/O2 radio frequency plasma. The length of the nanorods has been controlled by the ion etching time. The obtained morphologies were investigated by scanning electron microscopy. The gas sensing properties of the H-terminated diamond-based sensor structures are indicating that we have achieved high sensitivity to detect phosgene gas. Also, our sensor exhibited good selectivity between humid air and phosgene gas if the measurement is conducted at elevated temperatures, such as 140 °C. Furthermore, such sensor response rating could reach as high value as 4344 for the phosgene gas, which was evaluated for the sample consisting of the longest nanorods (up to 200 nm). 相似文献
45.
Miloslav Foistauer Karel Najzar Vcronika Sobotíková 《Numerical Functional Analysis & Optimization》2013,34(9-10):835-851
The paper is concerned with the study of an elliptic boundary value problem with a nonlinear Newton boundary condition. The existence and uniqueness of the solution of the continuous pioblem is a consequence of the monotone operator theory. The main attention is paid to the investigation of the finite element approximation using numeriral integration for the evaluation of boundary integrals. The error estimates for the solution of the discrete finite element problem are derived 相似文献
46.
Karel Dejaeger Frank Goethals Bart Baesens 《European Journal of Operational Research》2012,218(2):548-562
As a consequence of the heightened competition on the education market, the management of educational institutions often attempts to collect information on what drives student satisfaction by e.g. organizing large scale surveys amongst the student population. Until now, this source of potentially very valuable information remains largely untapped. In this study, we address this issue by investigating the applicability of different data mining techniques to identify the main drivers of student satisfaction in two business education institutions. In the end, the resulting models are to be used by the management to support the strategic decision making process. Hence, the aspect of model comprehensibility is considered to be at least equally important as model performance. It is found that data mining techniques are able to select a surprisingly small number of constructs that require attention in order to manage student satisfaction. 相似文献
47.
Petr tpni
ka Ivana Císaov Michal Hor
ek Karel Mach 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(10):1204-1205
The title compound, (η5‐cyclopentadienyl)[(1,2,3,4,5‐η)‐4‐ferrocenyl‐1,2,5,6‐tetrakis(trimethylsilyl)cyclohexa‐2,4‐dien‐1‐yl]titanium(II), [TiFe(C5H5)2(C23H42Si4)] or [Ti{η5‐C6H2{Fe(η5‐C5H4)(η5‐C5H5)}{Si(CH3)3}4}(η5‐C5H5)], possesses two directly linked metallocene units that subtend an angle of 52.9 (1)° (defined by the least‐squares planes of the directly connected π‐ligands) associated with the steric requirements of the bulky trimethylsilyl substituents. The cyclohexadienyl ligand adopts an envelope conformation; the perpendicular distance of its η5‐plane to the Ti atom is 1.512 (1) Å. 相似文献
48.
Marcel Špulák Zdeněk Novák Karel Palát Jiří Kuneš Jana Pourová Milan Pour 《Tetrahedron》2013,69(6):1705-1711
Contrary to a number of reports, alkylations of the privileged 3,4-dihydroquinazoline scaffold provide N3-alkylated products, and not 4-alkoxyquinazolines. To correctly assign the structure, 13C NMR shifts of the –Z–CHn– (Z=O, N) fragment are necessary; resonances in the 45–55 ppm range are indicative of N3-alkylation. Treatment of 3,4-dihydroquinazoline-4-one with p-TsCl afforded the N3-tosylated compound, whose reaction with an amine yielded the corresponding N3-alkyl derivative. A mechanism corroborated by 15N-labeling involving pyrimidine ring opening and recyclisation is proposed. Finally, the unambiguous preparation of 4-alkoxyquinazolines is described via treatment of 3,4-dihydroquinazoline-4-ones with PCl5 followed by an alkoxide. 相似文献
49.
Creating Space for Large Acceptors: Rational Biocatalyst Design for Resveratrol Glycosylation in an Aqueous System 下载免费PDF全文
Dr. Mareike E. Dirks‐Hofmeister Dr. Tom Verhaeghe Karel De Winter Prof. Dr. Tom Desmet 《Angewandte Chemie (International ed. in English)》2015,54(32):9289-9292
Polyphenols display a number of interesting properties but their low solubility limits practical applications. In that respect, glycosylation offers a solution for which sucrose phosphorylase has been proposed as a cost‐effective biocatalyst. However, its activity on alternative acceptor substrates is too low for synthetic purposes and typically requires the addition of organic (co‐)solvents. Here, we describe the engineering of the enzyme from Thermoanaerobacterium thermosaccharolyticum to enable glycosylation of resveratrol as test case. Based on docking and modeling studies, an active‐site loop was predicted to hinder binding. Indeed, the unbolted loop variant R134A showed useful affinity for resveratrol (Km=185 mM ) and could be used for the quantitative production of resveratrol 3‐α‐glucoside in an aqueous system. Improved activity was also shown for other acceptors, introducing variant R134A as promising new biocatalyst for glycosylation reactions on bulky phenolic acceptors. 相似文献
50.
High‐throughput workflow for identification of phosphorylated peptides by LC‐MALDI‐TOF/TOF‐MS coupled to in situ enrichment on MALDI plates functionalized by ion landing 下载免费PDF全文
Lukáš Krásný Petr Pompach Marcela Strnadová Radovan Hynek Karel Vališ Vladimír Havlíček Petr Novák Michael Volný 《Journal of mass spectrometry : JMS》2015,50(6):802-811
We report an MS‐based workflow for identification of phosphorylated peptides from trypsinized protein mixtures and cell lysates that is suitable for high‐throughput sample analysis. The workflow is based on an in situ enrichment on matrix‐assisted laser desorption/ionization (MALDI) plates that were functionalized by TiO2 using automated ion landing apparatus that can operate unsupervised. The MALDI plate can be functionalized by TiO2 into any array of predefined geometry (here, 96 positions for samples and 24 for mass calibration standards) made compatible with a standard MALDI spotter and coupled with high‐performance liquid chromatography. The in situ MALDI plate enrichment was compared with a standard precolumn‐based separation and achieved comparable or better results than the standard method. The performance of this new workflow was demonstrated on a model mixture of proteins as well as on Jurkat cells lysates. The method showed improved signal‐to‐noise ratio in a single MS spectrum, which resulted in better identification by MS/MS and a subsequent database search. Using the workflow, we also found specific phosphorylations in Jurkat cells that were nonspecifically activated by phorbol 12‐myristate 13‐acetate. These phosphorylations concerned the mitogen‐activated protein kinase/extracellular signal‐regulated kinase signaling pathway and its targets and were in agreement with the current knowledge of this signaling cascade. Control sample of non‐activated cells was devoid of these phosphorylations. Overall, the presented analytical workflow is able to detect dynamic phosphorylation events in minimally processed mammalian cells while using only a short high‐performance liquid chromatography gradient. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献