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1.
The density of neutral oxygen atoms in the MESOX set-up, one device of the PROMES-CNRS solar facilities, was determined by a fiber-optics catalytic probe (FOCP). Plasma was created in a flowing air within a quartz tube with the outer diameter of 5 cm by a 2.45 GHz microwave generator with the output power up to 1000 W. The flow of air was varied between 4 and 20 l/h. The O-atom density was found to increase monotonously with the increasing discharge power, and it decreased with the increasing flow rate. The degree of dissociation of oxygen molecules in the plasma column depended largely on the flow rate. At the air flow of 4 l/h it was about 80% but it decreased to about 20% at the flow of 20 l/h. 相似文献
2.
A new method for the determination of nickel in the presence of cobalt, based on the masking of the cobalt with potassium cyanide and hydrogen peroxide, is proposed. The yellow, or orange-yellow, complex of cobalt(III) is formed, from which cobalt is not displaced upon the addition of silver nitrate. Tetracyanonickelate, however, reacts quantitatively with silver nitrate, and the displaced nickel can be determined directly with EDTA, using Murexide as indicator. Up to 30 mg of cobalt can be tolerated in the solution. 相似文献
3.
Milan Jakubek Zdeněk Kejík Robert Kaplánek Hana Veselá David Sýkora Pavel Martásek 《Supramolecular chemistry》2018,30(3):218-226
Perimidine-based chelators 1 and 2 were prepared, and their structures were confirmed by 1H and 13C NMR, MS spectroscopy and elemental analysis. These compounds were studied as specific synthetic receptors for the recognition of transition metal ions. They exhibited high affinity and selectivity towards Cu(II) ions. The conditional binding constants, linear dynamic range and detection limit were determined by UV–vis spectroscopy. These parameters demonstrated high potential of the prepared synthetic receptors for the recognition and determination of Cu(II) ions. The minimum detectable concentrations of Cu(II) ions for the synthetic receptors 1 and 2 were 270 and 75 nM (R 2 = 0.9915 and 0.9964) in aqueous medium (water/DMSO; 99:1 (v/v)), respectively. 相似文献
4.
A review of the developments during the period 1965-70 in use of heteropoly acid salts, ferrocyanides and synthetic zeolites as ion-exchangers. 相似文献
5.
M. Šícha V. Veselý J. Studnička J. Prostějovský M. Novák 《Czechoslovak Journal of Physics》1962,12(12):919-929
Zusammenfassung Es wurde ein Verfahren zur Erregung von stationären Schichten, der Schichtungswelle und der laufenden Schichten in der Gleichstromentladung ausgearbeitet, das auf der Einwirkung eines Hochfrequenzfeldes auf einen kurzen Abschnitt der positiven Säule beruht. Dieses Verfahren wurde zum Studium aller drei angeführten Schichtungsarten in Neon benützt, insbesondere jedoch zum Studium des Zusammenhanges zwischen den laufenden und den stationären Schichten.Bei stationären Schichten wurden zweifache Strukturen festgestellt und es wurde deren Abhängigkeit vom Entladungsstrom und von der Größe des erregenden Hochfrequenzfeldes verfolgt.Bei der Schichtungswelle wurde die Stelle deren Entstehung ermittelt und es wurde nachgewiesen, daß das Hochfrequenzfeld diese Welle lokal an der Stelle dessen Einwirkung auf die positive Säule hervorruft.Bei den laufenden Schichten wurde deren Resonanzfrequenz in Abhängigkeit vom Entladungsstrom und die Abhängigkeit der Wellenlänge der Schichten von der Frequenz untersucht.Es wurde festgestellt, daß der extrapolierte Wert der Wellenlänge für die Nullfrequenz erheblich niedriger ist als die Länge der stationären Schichten. Weiter wurde eine Übereinstimmung der Frequenz der laufenden Schichten in der Schichtungswelle mit der Resonanzfrequenz der künstlich hervorgerufenen laufenden Schichten festgestellt.
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6.
Surface analysis of ripple pattern on PS and PEN induced with ring‐shaped mask due to KrF laser treatment
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O. Neděla P. Slepička P. Sajdl M. Veselý V. Švorčík 《Surface and interface analysis : SIA》2017,49(1):25-33
The approach for ripple nanopattern construction on surface of two polymer substrates [polyethylene naphthalate (PEN) and polystyrene (PS)] exposed by a KrF pulse excimer UV laser through a contact lithographic mask with circular slit was proposed in this paper. Thin layer of gold was deposited on samples after the laser treatment. Changes in the morphology of the surface of both the shielded and exposed areas of the substrates, as well as the dimensions of the laser‐induced periodic surface structures, were determined (by atomic force microscopy, laser confocal microscopy and scanning electron microscopy), compared with observations and measurements made on samples treated directly (without a contact mask) under the same conditions. The morphology of the interface between the treated and untreated regions was also closely studied. Surface chemistry of treated samples was studied in detail by X‐ray Photoelectron Spectroscopy. The detailed study of surface chemistry of modified PEN and PS revealed a significant increase of oxygen concentration for laser treated PS and increase of carboxyl groups in case of PEN. The potential application of this research can be found in biotechnology, micro technology and several other fields. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
7.
Libor Veselý 《Czechoslovak Mathematical Journal》2002,52(4):721-729
We give a full characterization of the closed one-codimensional subspaces of c
0, in which every bounded set has a Chebyshev center. It turns out that one can consider equivalently only finite sets (even only three-point sets) in our case, but not in general. Such hyperplanes are exactly those which are either proximinal or norm-one complemented. 相似文献
8.
The diffusion ot Ti atoms in the Ni77Si3B20 metallic glass was studied by the Auger electron spectroscopy. The temperature dependence of the diffusion coefficient obeys the Arrhenius relation with the activation energyE=1·7 eV and the pre-exponential factorD
0=0·86 × ×10–4 m2 s–1. Possible mechanisms of the atomic transport in metallic glasses are discussedThe authors wish to thank Dr. P. Duhaj for providing the metallic glass samples. 相似文献
9.
Barbieriková Z Bella M Kučerák J Milata V Jantová S Dvoranová D Veselá M Staško A Brezová V 《Photochemistry and photobiology》2011,87(1):32-44
Novel 7‐substituted 6‐oxo‐6,9‐dihydro[1,2,5]selenadiazolo[3,4‐h]quinoline ( SeQ(1–6) ) and 8‐substituted 9‐oxo‐6,9‐dihydro[1,2,5]selenadiazolo[3,4‐f ]quinoline derivatives ( SeQN(1–5) ) with R7, R8 = H, COOC2H5, COOCH3, COOH, COCH3 or CN were synthesized and their spectral characteristics were obtained by UV/Vis spectroscopy. Ultraviolet A photoexcitation of the selenadiazoloquinolones in dimethylsulfoxide or acetonitrile resulted in the formation of paramagnetic species coupled with molecular oxygen activation generating the superoxide radical anion or singlet oxygen, evidenced by electron paramagnetic resonance spectroscopy. The cytotoxic/photocytotoxic impact of selenadiazoloquinolones on murine and human cancer cell lines was demonstrated using the derivative SeQ5 (with R7 = COCH3). 相似文献
10.