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931.
Jan Majling Luboš Bača Jana Kozánková Miroslav Kocifaj Ekkehard Füglein 《Journal of Thermal Analysis and Calorimetry》2013,114(1):417-422
Present results reveal basic features of the optical transmission thermo-analytical method in its employment to investigate the oxidative pyrolysis of supported thin polyvinylpyrrolidone films. The OT curves naturally vary in shapes and positions on the time/temperature scales, respective to the examined rate of sample heating, to the wavelengths of radiation as well as to the film thickness. Recorded OT curves exhibit characteristic shapes with well-expressed OT minima. The temperatures at which the OT minima appear are in a linear relationship with heating rates of samples, at a frequency of radiation as well as a film thickness kept constant. Similarly, the OT values at which the OT minima appear are in a linear relationship with film thickness, at a frequency of the radiation and sample heating rate unchanged. 相似文献
932.
Hidekazu Miyaji Miroslav Dudic Ivan Prokes Mark E. Light Thomas Gelbrich 《Supramolecular chemistry》2013,25(5):385-390
A convenient method for measuring the dimerisation constant in solution of a calix[4]arenedicarboxylic acid is reported. This compound also co-crystallises with a bis(amidopyridyl)calix[4]arene as independent tubular calixarene stacks that are cross-linked via carboxyl–amidopyridyl hydrogen bonding and π-stacking of the amidopyridyl arms. 相似文献
933.
Smejkal P Sisková K Vlcková B Pfleger J Sloufová I Slouf M Mojzes P 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2003,59(10):2321-2329
A four step Ag foil laser ablation-Ag nanoparticle fragmentation procedure in ultrapure water was carried out both under argon and in air. Pulses of a high power Nd/YAG laser were used for laser ablation (1064 nm) and for the three step Ag hydrosol treatment in the absence of Ag foil in the sequence 1064-532-1064 nm. Transmission electron microscopy (TEM) and surface plasmon (SP) extinction spectra provide evidence of Ag nanoparticle fragmentation in the second and third step of the procedure carried out under argon. While polydispersity of Ag hydrosol increases in the second step, both the polydispersity and the mean size of the nanoparticles are reduced in the third step. Qualitative and quantitative surface-enhanced Raman scattering (SERS)/surface-enhanced resonance Raman scattering (SERRS) spectral probing of systems with Ag hydrosols and the selected adsorbates at 514.5 nm excitation shows that Ag hydrosols obtained in the second step of the preparation procedure carried out in air are the most suitable substrates for SERS/SERRS experiments performed at this excitation wavelength. 相似文献
934.
935.
Luc Giraud Julien Langou Miroslav Rozložník Jasper van den Eshof 《Numerische Mathematik》2005,101(1):87-100
This paper provides two results on the numerical behavior of the classical Gram-Schmidt algorithm. The first result states that, provided the normal equations associated with the initial vectors are numerically nonsingular, the loss of orthogonality of the vectors computed by the classical Gram-Schmidt algorithm depends quadratically on the condition number of the initial vectors. The second result states that, provided the initial set of vectors has numerical full rank, two iterations of the classical Gram-Schmidt algorithm are enough for ensuring the orthogonality of the computed vectors to be close to the unit roundoff level.The work of the second author was supported in part by the US Department of Energy, Office of Basic Energy Science under LAB03-17 initiative, DOE contract No. DE-FG02-03ER25584, and in part by the TeraScale Optimal PDE Simulations (TOPS) SciDAC, DoE Contract No. DE-FC02-01ER25480The work of the third author was supported by the project 1ET400300415 within the National Program of Research ‘‘Information Society’’ and by the GA AS CR under grant No. IAA1030405. 相似文献
936.
We give a duality for the variety of bounded distributive lattices that is not full (and therefore not strong) although it
is full but not strong at the finite level. While this does not give a complete solution to the “Full vs Strong” Problem,
which dates back to the beginnings of natural duality theory in 1980, it does solve it at the finite level. One consequence
of this result is that although there is a Duality Compactness Theorem, which says that if an alter ego of finite type yields
a duality at the finite level then it yields a duality, there cannot be a corresponding Full Duality Compactness Theorem.
Received October 1, 2002; accepted in final form November 10, 2004. 相似文献
937.
A mesoscopic rheological model of suspensions of semiflexible fibers in polymeric fluids is formulated. Consequences of the model are compared with results of experimental observations of the rheological properties in a simple shear flow. The model takes into account the fiber-fiber and fiber-polymer interactions (in the free energy and the mobility coefficients) and the semiflexible nature of the fibers (in the choice of the Khokhlov-Semenov entropy). 相似文献
938.
Silliková Veronika Dulanská Silvia Horník Miroslav Jakubčinová Jana Mátel Ľubomír 《Journal of Radioanalytical and Nuclear Chemistry》2020,324(3):1225-1236
Journal of Radioanalytical and Nuclear Chemistry - Cesium-137 is an important indicator of radioactive pollution in the aquatic environment. The aim of this study was to increase the sorption... 相似文献
939.
Dr. Elmira Mohammadi Lukáš Petera Dr. Homa Saeidfirozeh Antonín Knížek Dr. Petr Kubelík Dr. Roman Dudžák Dr. Miroslav Krůs Dr. Libor Juha Prof. Svatopluk Civiš Rémi Coulon Dr. Ondřej Malina Dr. Juri Ugolotti Dr. Václav Ranc Prof. Michal Otyepka Prof. Jiří Šponer Dr. Martin Ferus Dr. Judit E. Šponer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(52):12075-12080
Terrestrial volcanism has been one of the dominant geological forces shaping our planet since its earliest existence. Its associated phenomena, like atmospheric lightning and hydrothermal activity, provide a rich energy reservoir for chemical syntheses. Based on our laboratory simulations, we propose that on the early Earth volcanic activity inevitably led to a remarkable production of formic acid through various independent reaction channels. Large-scale availability of atmospheric formic acid supports the idea of the high-temperature accumulation of formamide in this primordial environment. 相似文献
940.
Ludk Toman Miroslav Janata Jií Spv
ek Petr Vl
ek Petra Ltalov Bohumil Masa Antonín Sikora 《Journal of polymer science. Part A, Polymer chemistry》2004,42(23):6098-6108
ABCBA‐type pentablock copolymers of methyl methacrylate (MMA), styrene (S), and isobutylene (IB) were prepared by a three‐step synthesis, which included atom transfer radical polymerization (ATRP) and cationic polymerization: (1) poly(methyl methacrylate) (PMMA) with terminal chlorine atoms was prepared by ATRP initiated with an aromatic difunctional initiator bearing two trichloromethyl groups under CuCl/2,2′‐bipyridine catalysis; (2) PMMA with the same catalyst was used for ATRP of styrene, which produced a poly(S‐b‐MMA‐b‐S) triblock copolymer; and (3) IB was polymerized cationically in the presence of the aforementioned triblock copolymer and BCl3, and this produced a poly(IB‐b‐S‐b‐MMA‐b‐S‐b‐IB) pentablock copolymer. The reaction temperature, varied from ?78 to ?25 °C, significantly affected the IB content in the product; the highest was obtained at ?25 °C. The formation of a pentablock copolymer with a narrow molecular weight distribution provided direct evidence of the presence of active chlorine at the ends of the poly(S‐b‐MMA‐b‐S) triblock copolymer, capable of the initiation of the cationic polymerization of IB in the presence of BCl3. A differential scanning calorimetry trace of the pentablock copolymer (20.1 mol % IB) showed the glass‐transition temperatures of three segregated domains, that is, polyisobutylene (?87.4 °C), polystyrene (95.6 °C), and PMMA (103.7 °C) blocks. One glass‐transition temperature (104.5 °C) was observed for the aforementioned triblock copolymer. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 6098–6108, 2004 相似文献