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11.
12.
Mariana Ušáková Jozef Lukáč Rastislav Dosoudil Vladimír Jančárik Anna Grusková Elemír Ušák Jozef Sláma Jan Šubrt 《Journal of Materials Science: Materials in Electronics》2007,18(12):1183-1189
The paper is devoted to the preparation of NiZn ferrite with small substitutions of copper by means of ceramic technology.
The influence of small Cu substitution on the microstructural and magnetic properties of NiZn ferrites have been analysed
by means of various experimental methods and interpreted from the point of view of preparation technology optimisation and
possible applications of such materials. A strong correlation between the substituent content and resulting properties has
been observed, thus allowing preparation of material with the properties tailored for any particular application. 相似文献
13.
Dr. Veronika Papoušková Dr. Pavel Kadeřávek Olga Otrusinová Alžbeta Rabatinová Dr. Hana Šanderová Jiří Nováček Dr. Libor Krásný Prof. Vladimír Sklenář Dr. Lukáš Žídek 《Chembiochem : a European journal of chemical biology》2013,14(14):1772-1779
The partially disordered δ subunit of RNA polymerase was studied by various NMR techniques. The structure of the well‐folded N‐terminal domain was determined based on inter‐proton distances in NOESY spectra. The obtained structural model was compared to the previously determined structure of a truncated construct (lacking the C‐terminal domain). Only marginal differences were identified, thus indicating that the first structural model was not significantly compromised by the absence of the C‐terminal domain. Various 15N relaxation experiments were employed to describe the flexibility of both domains. The relaxation data revealed that the C‐terminal domain is more flexible, but its flexibility is not uniform. By using paramagnetic labels, transient contacts of the C‐terminal tail with the N‐terminal domain and with itself were identified. A propensity of the C‐terminal domain to form β‐type structures was obtained by chemical shift analysis. Comparison with the paramagnetic relaxation enhancement indicated a well‐balanced interplay of repulsive and attractive electrostatic interactions governing the conformational behavior of the C‐terminal domain. The results showed that the δ subunit consists of a well‐ordered N‐terminal domain and a flexible C‐terminal domain that exhibits a complex hierarchy of partial ordering. 相似文献
14.
The acid-catalyzed decomposition of unusually stable 1-(2,1-benzisothiazol-3-yl)-3-phenyltriazenes in either aqueous perchloric acid or an aqueous mixture of perchloric and acetic acid was studied under pseudo-first order reaction conditions at 25 °C. Different products were obtained according to substitution on nitrogen N-3. For a triazene carrying hydrogen, the corresponding 3-amino-2,1-benzisothiazole and benzenediazonium salts were formed whereas in the case of substitution by an alkyl group (methyl and n-butyl) the 2,1-benzisothiazole-3-diazonium salt and N-alkylaniline were obtained. The observed rate constant (kobs) of the acid-catalyzed decomposition increased, initially, nonlinearly with increasing concentration of acid. Subsequently, kobs decreased slightly and at high acid concentration, increased steeply once again. An A-SE2 mechanism in which protonation of the triazene nitrogen proceeds simultaneously with cleavage of the N–N bond is proposed. Tautomerism of 1-(2,1-benzisothiazol-3-yl)-3-phenyltriazene was investigated using 1H NMR spectroscopy. 相似文献
15.
Zdeňka Řiháková Milada Plocková Vladimír Filip Jan Šmidrkal 《European Food Research and Technology》2001,213(6):488-490
The antifungal effects of lauric acid and four lauric acid derivatives (monolauroylglycerol, D-laurate A, T-laurate A, 6-O-lauroysucrose) were tested on the spore germination and the growth rate of Aspergillus niger DMF 0801. The results showed that the tested substances varied in their antifungal activity and they also confirmed the relation of the structure of tested substances and their antifungal effects. Monolauroylglycerol at concentration level between 0.2 and 1.8 mmol l-1 caused the highest inhibition of spore outgrowths whereas 6-O-lauroysucrose at concentration between 0.05 and 1.8 mmol l-1 did not exhibit inhibition of spore germination. The inhibition of colony growth rate was detected mainly at presence of 6-O-lauroysucrose. 相似文献
16.
Master equations in the Lindblad form describe evolution of open quantum systems that are completely positive and simultaneously have a semigroup property. We analyze the possibility to derive this type of master equations from an intrinsically discrete dynamics that is modelled as a sequence of collisions between a given quantum system (a qubit) with particles that form the environment. In order to illustrate our approach we analyze in detail how the process of an exponential decay and the process of decoherence can be derived from a collision-like model in which particular collisions are described by SWAP and controlled-NOT interactions, respectively.Presented at the 36th Symposium on Mathematical Physics, “Open Systems & Quantum Information”, Toruń, Poland, June 9-12, 2004. 相似文献
17.
This paper is aimed at theoretical aspects of the application of superconducting quantum magnetometers in measurement of beam
intensity of electrically charged particles in superconductive accelerators. The parameters of antenna system, which picks
up the magnetic field induced by unidirectional component of the accelerated particles current, are examined. From the analysis
it follows that for accelerators with a beam trajectory radius of the order of10
1
m the spectral sensitivity limit is of the order of (10
2–103) elementary particles/(cycleHz
1/2). 相似文献
18.
Strohalm M Strohalm J Kaftan F Krásný L Volný M Novák P Ulbrich K Havlíček V 《Analytical chemistry》2011,83(13):5458-5462
Traditional tissue-sectioning techniques for histological samples utilize various embedding media to stabilize the tissue on a sectioning target and to provide a smooth cutting surface. Due to the ion suppression effect in MALDI ionization and number of background peaks in the low-mass region, these media are not suitable for mass spectrometry imaging (MSI) experiments. To overcome this, droplets of water are often used to mount the tissue on a sectioning target, but the ice block formed around the tissue does not provide a good support for sectioning of fragile samples. In this work, we propose a novel embedding media, compatible with MALDI ionization and MSI experiments, based on poly[N-(2-hydroxypropyl)methacrylamide] (pHPMA). Using a reversible addition-fragmentation chain transfer polymerization technique, well-defined pHPMA polymer with narrow mass distribution was prepared. Benefits of the resulted pHPMA-based embedding media were tested on different tissue samples. 相似文献
19.
Petr Matula Pavel Matula Michal Kozubek Vladimír Dvorák 《IEEE transactions on image processing》2006,15(8):2388-2396
Typical time intervals between acquisitions of three-dimensional (3-D) images of the same cell in live cell imaging are in the orders of minutes. In the meantime, the live cell can move in a water basin on the stage. This movement can hamper the studies of intranuclear processes. We propose a fast point-based image registration method for the suppression of the movement of a cell as a whole in the image data. First, centroids of certain intracellular objects are computed for each image in a time-lapse series. Then, a matching between the centroids, which have the maximal number of pairs, is sought between consecutive point sets by a 3-D extension of a two-dimensional fast point pattern matching method, which is invariant to rotation, translation, local distortion, and extra/missing points. The proposed 3-D extension assumes rotations only around the z axis to retain the complexity of the original method. The final step involves computing the optimal fully 3-D transformation between images from corresponding points in the least-squares manner. The robustness of the method was evaluated on generated data. The results of the simulations show that the method is very precise and its correctness can be estimated. This article also presents two practical application examples, namely the registration of images of HP1 domains and the registration of images of telomeres. More than 97% of time-consecutive images were successfully registered. The results show that the method is very well suited to live cell imaging. 相似文献
20.
Vladimír Zivica 《Bulletin of Materials Science》2003,26(6):605-608
Reinforced concrete structures during their exploitation may be exposed to the common action of carbonation and chlorides
causing corrosion of steel reinforcement. Therefore, the related data seem to be interesting and important when the evaluation
of the service life of the structures is the object of interest. This fact was a motivation for the present experimental study
on the sequence of action of chloride solutions and carbonation of the embedding concrete. The results obtained show that
carbonation of concrete foregoing the action of chloride solutions may intensify the process of corrosion of steel reinforcement
in comparison to the converse sequence of the action of mentioned media. At the same time the natrium chloride solution has
been shown as a more aggressive medium opposite to the calcium and magnesium chloride solutions. 相似文献