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91.
Viktor Csokai Diem Lan Ha Mai Olívia Varga Klára Tóth Miklós Kubinyi Alajos Grün 《Tetrahedron》2008,64(6):1058-1063
Novel fluorogenic 1,3-alt thiacalix[4](N-phenylazacrown-5)ether ionophore has been synthesized by conjugation of the N-phenyl group with borondipyrromethene (BODIPY) fluorophore moiety. The ionophore exhibits pronounced off-on type fluorescent responses to some transition metal ions, in particular to Cu2+. In a PVC membrane electrode, distinct Ag+ selectivity was observed in potentiometric transduction. 相似文献
92.
93.
Reyes Malavé Osuna Rocio Ponce Ortiz Mari Carmen Ruiz Delgado Valentin G Nenajdenko Viktor V Sumerin Elizabeth S Balenkova Víctor Hernández Juan Teodomiro López Navarrete 《Chemphyschem》2007,8(5):745-750
Herein, we study the conjugation properties of three different thienoacenes, each of which has three or four fused thiophene rings, by means of Fourier transform Raman spectroscopy. The B3LYP/6-31G** vibrational analysis of all of the collected spectroscopic data evidences that the selective enhancement of a limited number of Raman scatterings is related to the occurrence in the three thienoacenes of a vibronic coupling between the lowest unoccupied frontier molecular orbital (LUMO) and some Raman-active skeletal nu(C==C) stretching modes of 1600-1300 cm(-1). 相似文献
94.
Ivan N. Bardasov Anastasiya U. Alekseeva Sergey S. Chunikhin Viktor A. Tafeenko Oleg V. Ershov 《Tetrahedron letters》2017,58(41):3919-3923
The synthesis of triarylpyridine derivatives containing a buta-1,3-diene-1,1,3-tricarbonitrile fragment via the base-promoted reactions of aromatic aldehydes, 2-phenylacetophenone and a malononitrile dimer in the presence of an oxidant is described. The influence of aryl substituents in the 4-position on the optical properties is also reported. 相似文献
95.
Rožkov Andrej Jobbágy Viktor Özçayan Gulten 《Journal of Radioanalytical and Nuclear Chemistry》2017,314(2):773-780
A liquid scintillation counting (LSC) measurement method optimization for the gross α/β activity analysis in drinking waters with different chemical and radionuclide composition was performed. The optimized method was suitable to provide gross radioactivity results in drinking waters with the levels of the accuracy and precision similar to those obtained using other radioactivity screening techniques. Robust LSC results contributed to the calculation of gross α/β activity reference values of EC-JRC interlaboratory comparison water samples in 2012. Some of the most common errors in the determination of the gross radioactivity using the LSC are presented.
相似文献96.
Hydrogels are crosslinked polymers of hydrophilic monomers. Hydrogels can swell and shrink in aqueous solutions. The swelling behavior of hydrogels and the encountered phase behavior are of interest in many areas, e.g., in biotechnology, membrane science and controlled drug release. This contribution presents the criteria for such phase equilibria and a previously developed thermodynamic model for correlating/predicting the swelling and shrinking of hydrogels. The application of the method is demonstrated by describing the swelling equilibrium of some synthetic, non-ionic N-isopropyl acrylamide (N-IPAAm) hydrogels in aqueous solutions of sodium chloride at 298 K. Furthermore, new experimental results are presented for the degree of swelling of synthetic hydrogels that contain – besides the non-ionic monomer N-IPAAm – either a combination of a cationic comonomer (here, N-[3-(dimethylamino)propyl]methacrylamide (DMAPMA)) and an anionic comonomer (here, 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS)) or a zwitterionic comonomer (here, [3-(methacryloylamino)propyl]dimethyl(3-sulfopropyl)ammonium hydroxide inner salt (MPSA)). These gels were equilibrated with aqueous solutions of sodium chloride at 298 K. 相似文献
97.
Vyacheslav Ya. Sosnovskikh Dmitri V. Sevenard Viktor O. Iaroshenko 《Tetrahedron》2010,66(36):7322-7328
The reactions of 3-formylthiochromone with o-phenylenediamines, o-aminobenzenethiol, and indoles proceeded at the aldehyde group to give 3-(benzimidazol-2-yl)thiochromone, 3-(benzothiazol-2-yl)thiochromone, and 3-di(indol-3-yl)methylthiochromones, respectively. 3-Formyl- and 3-cyanothiochromones react with primary aromatic amines and phenylhydrazine to give the corresponding anils and phenylhydrazones of 3-formyl- and 2-amino-3-formylthiochromones. The reaction of 3-cyanochromones with o-phenylenediamines gave 2-amino-3-[(2-aminophenyl)iminomethyl]-4H-chromen-4-ones. 相似文献
98.
Viktor Jobbágy Norbert Kávási János Somlai Borbála Máté Tibor Kovács 《Microchemical Journal》2010,94(2):159-165
Hungary is rich in spring waters. A survey studying the naturally occurring alpha emitter radionuclides in 30 frequently visited and regularly consumed spring waters was conducted out in the Balaton Upland region of Hungary.226Ra, 224Ra, 234U, 238U and 210Po activity concentrations were determined by using alpha spectrometry after separation from matrix elements. Average concentration (mBq L− 1) of 226Ra, 224Ra, 234U, 238U and 210Po in the spring waters is varied from 2.1 to 601, from < 1.1 to 65.4, from 3.9 to 741.9, from < 0.44 to 274.3 and from 2 to 15.2 respectively. In most cases radioactive disequilibrium was observed between uranium and radium isotopes. The doses for the analyzed samples of spring water are in the range 3.59–166.73 μSv y− 1 with an average 18.2 μSv y− 1 .This is well below the 100 μSv y− 1 reference level of the committed effective dose recommended by WHO. Only one water sample had a dose higher than 100 μSv y− 1, mainly due to the contribution from radium (226Ra, 224Ra) and 210Po isotopes. This study provides important information for consumers and authorities about their internal radiological exposure risk from spring water intake. 相似文献
99.
Viktor F. Ivanov Oxana L. Gribkova Olga D. Omelchenko Alexander A. Nekrasov Vladimir A. Tverskoy Anatoly V. Vannikov 《Journal of Solid State Electrochemistry》2010,14(11):2011-2019
Various polyaniline (PANI) interpolymer complexes with polyacids in the form of molecular solutions were synthesized by chemical
oxidative polymerization of aniline in the presence of water-soluble poly-(2-acrylamido-2-methyl-1-propanesulfonic acid) (flexible
backbone), poly-p,p′-(2,2′-disulfoacid)-diphenylene-terephthalamide (t-PASA, rigid backbone), and their mixtures in different ratios. The complexes
were characterized by UV-Vis-near infrared spectroscopy in solutions; also, the films’ drop-casts from these solutions were
investigated by cyclic voltammetry, spectroelectrochemical, direct current (DC) conductivity, and atomic force microscopy
(AFM) measurements. It was shown that the nature of polyacid affects the shape of spectra and the dynamics of their changes.
The character of spectral changes during the matrix synthesis of PANI in the presence of mixtures of the rigid-chain and flexible-chain
matrixes and the study of spectral properties of the obtained PANI solutions demonstrates the existence of the rigid-matrix
domination effect in the process of formation of PANI interpolymer complexes. Spectral properties of the obtained PANI complexes
with the mixtures of flexible-chain and rigid-chain polyacids of different ratios (3:1, 1:1, 1:3, and 1:6) are very similar
to those ones for the complex with rigid-chain t-PASA. At the same time, there is a correlation between the electrical conductivity
and morphology of the films of PANI complexes and their composition, the conductivity passing through a minimum for the complexes
with the polyacid mixtures (6:1, 3:1, and 1:1). 相似文献
100.
Gy?rgy Székely Viktor Farkas László Párkányi Tünde Tóth Miklós Hollósi Péter Huszthy 《Structural chemistry》2010,21(1):277-282
This paper describes the structures of pseudo-18-crown-6 compounds (2, R,R-4 and 5) in the crystals together with theoretical calculations of the electronic circular dichroism (ECD) spectra. The achiral macrocyclic
phosphinic acid 5 forms hydrogen-bonded dimers in the crystal. The O1–O2 distance (2.489 Ǻ) indicates strong H-bondings. The conformations
of the macrorings of the achiral phosphinate 2 and the monomers of the achiral phosphinic acid 5 are chiral. A comparison of the torsion angles of the achiral methyl phosphinate 2 and the monomeric units of achiral 5 indicates a similar geometry. The torsion angles of the chiral methyl phosphinate (R,R)-4 differ more significantly from those in achiral methyl phosphinate 2. A negative 1Bb exciton couplet was observed in the ECD spectrum of monomeric (R,R)-6 in MeOH and H2O as in the spectra of (R,R)-4 in all solvents. To support the idea that (R,R)-4 has basically the same conformation in the crystal and in solution, the ECD spectrum of (R,R)-4 was calculated using the geometry of the molecule in the crystal. The calculated ECD spectrum shows a reasonable agreement
with the ECD spectra obtained in solution. This shows that the steric structure observed in the crystal is predominant in
solution as well. 相似文献