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21.
A. P. Mazurek J. Cz. Dobrowolski J. Sadlej E. Bednarek L. Kozerski 《Journal of Molecular Structure》2000,520(1-3):45-52
The piperazine and triethylamine complexes of genistein, exhibiting high immunosuppressant activity, were ab initio modeled at RHF/6-31G** level and results were compared with those obtained for genistein–morpholine complexes by X-ray, NMR, and theoretical methods. The most stable genistein–piperazine complex is formed due to hydrogen bonding of genistein's OH group at position C7 to piperazine's nitrogen atom. In the most stable genistein–triethylamine complex genistein's OH group at position C4′ (position para to phenyl substituent) and trimethylamine nitrogen atom are engaged in hydrogen bond formation. The calculations confirmed our previous NMR conclusion that piperazine is more strongly complexed by genistein than is morpholine or triethylamine. The theoretical 13C NMR spectra correlate fairly well with the experimental spectra. 相似文献
22.
El?bieta Jartych Mariusz Mazurek Dionizy Czekaj 《Journal of magnetism and magnetic materials》2010,322(1):51-55
X-ray diffraction and Mössbauer spectroscopy were applied as complementary methods to investigate the structure and hyperfine interactions in the series of Bim+1Ti3Fem−3O3m+3 Aurivillius compounds with m=4, 6, 7 and 8. Samples were synthesized by the solid-state sintering method at various temperatures. As X-ray diffraction analysis proved, the compounds formed single phases at temperature above 993 K. Mössbauer studies have confirmed diffraction measurements. Compounds synthesized at 993 K contained residual hematite, however these sintered at elevated temperatures were single-phased materials. Room-temperature Mössbauer spectra of Bim+1Ti3Fem−3O3m+3 compounds revealed their paramagnetic properties, what is consistent with the literature data concerning the Néel temperature of these ceramics (TN is smaller than room temperature). Detailed analysis of MS spectra allowed to state that iron ions may occupy both tetrahedral and octahedral sites in the crystallographic lattice of Aurivillius compounds. 相似文献
23.
L. A. Fedorova V. V. Mazurek N. A. Shirokov L. D. Turkova 《Reaction Kinetics and Catalysis Letters》1980,15(3):361-365
Polymerization of acrylonitrile by tris-(-allyl)chromium-pyridine in dimethyl formamide has been studied. Assumptions on the nature of active centers are experimentally supported.
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24.
The vibrational (FT-IR and FT-Raman) and NMR (1H and 13C) spectra of Ca, Mn, and Zn complexes with ortho-, meta-, and para-iodobenzoic acids have been studied. The solid state samples of all complexes have been measured within the range 4000–400 cm−1, while water solutions of ortho-iodobenzoates within the range 4000–800 cm−1. Based on previous experimental data and normal mode calculations for simpler complexes the assignment of bands observed in vibrational spectra of studied compounds has been done. Some significant differences in vibrational structure (frequency and intensity of selected bands) have been observed and discussed. The effect of metal on ring vibrations and carboxylic anion stretching and deformation has been investigated. Also, influence of iodine substitution on the aromatic ring and carboxylic anion, depending on iodine ring position, has been discussed. In case of soluble compounds, wavenumbers of characteristic bands of water solution samples have been compared with wavenumbers of corresponding bands of solid state samples. 相似文献
25.
H. Mazurek D. R. Day E. W. Maby J. S. Abel S. D. Senturia M. S. Dresselhaus G. Dresselhaus 《Journal of Polymer Science.Polymer Physics》1983,21(4):537-551
Ion implantation of impurities into thin films of poly(p-phenylene sulfide) (PPS) is found to increase the conductivity of the material by up to 12 orders of magnitude. The increase is stable under exposure to ambient conditions, in contrast to the instability of the conductivity increases in PPS produced by chemical doping with AsF5. PPS films 0.1–0.2 μm thick are spin cast from solution onto interdigitated electrodes patterned on an oxidized silicon substrate. The room-temperature interelectrode resistance is measured as a function of implantation fluence. An estimate of film conductivity is obtained from this resistance with a simple model for the electrode and film geometry. A first experiment yielded similar conductivity increases for implantation of either arsenic or krypton. At a fluence of 1 × 1016cm?;2, which corresponds to an average impurity concentration of 2.5 × 1021cm?3, the conductivity reaches an apparently saturated value of 1.5 × 10?5 (Ω cm)?1. Infrared spectra of the films before and after implantation suggest that crosslinking may be present in the implanted films, and Auger studies show stoichiometric changes throughout the implanted layer. These results suggest that the observed conductivity changes are the result of molecular rearrangements produced by the implantation rather than the result of specific chemical doping. Specific chemical doping may, however, explain the results of a second experiment in which implantation of bromine resulted in substantially larger conductivities found to increase at an approximate linear rate from a value of 1.0 × 10?4 (Ω cm)?1 at a fluence of 1 × 1016 cm?2 to a value of 4.0 × 10?4 (Ω cm)?1 at a fluence of 3.16 × 1016 cm?2. 相似文献
26.
27.
Ohne Zusammenfassung 相似文献
28.
Henryk Bem Ewa Maria Bem Joanna Krawczyk Marcin Płotek Sławomira Janiak Daria Mazurek 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(3):2229-2232
Plastic PicoRad detectors with activated charcoal have been used for radon monitoring in local kindergartens and schools in two cities, Kalisz and Ostrów Wielkopolski, in the region of Greater Poland. Detectors were exposed for a standard time of 48 h during the autumn and winter of 2011 in 103 rooms (Kalisz) and 55 rooms (Ostrów Wlkp), respectively. The detectors were calibrated in the certified radon chamber of the Central Laboratory for Radiological Protection in Warsaw, Poland. The arithmetic and geometric means of indoor radon concentrations in the examined rooms were 46.0 and 30.3 Bq/m3 for Kalisz and 48.9 and 29.8 Bq/m3 for Ostrów Wlkp, respectively. The measured levels of the indoor radon concentrations were relatively low, since the main source of indoor radon for these low storey (max. three storeys) buildings is radon escaping from the underlying soil with a low 226Ra concentration (~15 Bq/m3). Therefore, the calculated annual effective doses from that source for the children in Kalisz and Ostrów Wlkp were also low 0.35 mSv. 相似文献
29.
Henryk Bem Urszula Plota Marta Staniszewska Ewa Maria Bem Daria Mazurek 《Journal of Radioanalytical and Nuclear Chemistry》2014,299(3):1307-1312
Activity concentration of the 222Rn radionuclide was determined in drinking water samples from the Sothern Greater Poland region by liquid scintillation technique. The measured values ranged from 0.42 to 10.52 Bq/dm3 with the geometric mean value of 1.92 Bq/dm3. The calculated average annual effective doses from ingestion with water and inhalation of this radionuclide escaping from water were 1.15 and 11.8 μSv, respectively. Therefore, it should be underlined that, generally, it’s not the ingestion of natural radionuclides with water but inhalation of the radon escaping from water which is a substantial part of the radiological hazard due to the presence of the natural radionuclides from the uranium and thorium series in the drinking water. 相似文献
30.
Joanna Biernacka Katarzyna Betlejewska-Kielak Janina Witowska-Jarosz Ewa Kłosińska-Szmurło Aleksander P. Mazurek 《Journal of inclusion phenomena and macrocyclic chemistry》2014,78(1-4):437-443
Complexation of alendronate sodium (AlnNa) with β-cyclodextrin (β-CD) was studied by means of ESI-mass spectrometry. The experimental results show that stable 1:1 inclusion complexes between selected bisphosphonates and β-CD were formed. In addition, complexes with different stoichiometry were observed. DFT/B3LYP calculations were performed to elucidate the different inclusion behavior between alendronate and β-CD. Molecular modeling showed that the inclusion complex of Aln-β-CD where the two phosphonate groups bound to the central carbon atom of bisphosphonate were inserted into the cavity of β-CD from its “top” side was thermodynamically more favorable than when they were inserted from its “bottom” side; the complexation energy was ?74.05 versus ?60.85 kcal/mol. The calculations indicated that the formation of conventional hydrogen bonds was the main factor for non-covalent β-CD:Aln complex formation and stabilization in the gas phase. 相似文献