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991.
Tadeusz Wibig 《Central European Journal of Physics》2007,5(4):528-538
A new feature in the spectrum of ultra high energy cosmic rays (UHECR) has been announced in the paper by Berezinsky, Gazizov
and Kachelrieβ. The ratio of the solution of the exact transport equation to its solution in the continuous energy loss limit
shows intriguing features which, according to the Authors, are related to the very nature of the energy loss processes of
UHECR: the very sharp second dip predicted at 6.3 × 1019 eV can be used as an energy calibration point and also as the UHECR mass indicator for big future cosmic ray experiments.
In the present paper we would like to advocate that this statement is an overinterpretation. The second dip is a result of an inappropriate approximation used, and thus it cannot help to understand the nature of UHECR in any way.
相似文献
992.
Tadeusz M. Krygowski Marcin Palusiak Anna Płonka Joanna E. Zachara‐Horeglad 《Journal of Physical Organic Chemistry》2007,20(5):297-306
Molecular geometry of 10 isomeric nitronaphtholate ions (excluding peri‐ and ortho‐type substituted systems), 1‐ and 2‐naphtholate ions, 1‐ and 2‐nitronaphthalene, meta‐ and para‐nitrophenolate, phenolate, and nitrobenzene were optimized at B3LYP/6‐311G** level of approximation. Substituent effect stabilization energy (SESE), geometry‐based aromaticity index HOMA, magnetism‐based indices NICS, NICS(1), NICS(1)zz, and parameters characterizing Bond Critical Points (BCP) (ρ, ?2ρ, ellipticity, ion/cov) of the Bader AIM theory were used to characterize transmitting properties for substituent effect through the naphthalene moiety. It results from our study that the studied systems could be clearly divided into two groups, (i) a para‐type group, where the intramolecular charge transfer between the π‐electron donating and π‐electron accepting substituents can be described by canonical forms with charge separation (as in the case of para‐nitrophenolate) and (ii) a meta‐type group, where this transfer requires using canonical forms with double charge separation (as in the case of meta‐nitrophenolate). Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
993.
Andrzej Maślanskiewicz Tadeusz Glowiak Henryk Chojnacki Leszek Skrzypek Adam Niedbala 《Journal of chemical crystallography》1995,25(4):165-169
The crystal and molecular structures of two isomeric 3,4- and 4,3-chloro-(methylthio)quinolines have been determined. For 3-chloro-4-(methylthio)-quinoline (3-Cl–4-MeS–Q); triclinic, space group
,a=7.199(3),b=7.919(3),c=8.921(3) Å, =89.74(3), =74.29(3), =78.55(3)°. For 4-chloro-3-(methylthio)quinoline (4-Cl–3-MeS–Q): monoclinic, space group P21/n,a=12.860(4),b=5.424(2),c=13.434(4) Å, =90.84(3)°. The values of the Cl...S distance as well as those for the Cl–C–C(S) and (Cl)C–C–S angles indicate the attractive interaction between ortho-situated heteroatoms in isomer 4-Cl–3-MeS–Q contrary to the effects observed in the case of 3-Cl–4-MeS–Q. The conclusions were confirmed by calculations of atomic charges withab initio method 4-31G basis set, which show positively charged sulfur atom in 4-Cl–3-MeS–Q and negatively charged sulfur in 3-Cl–4-MeS–Q.Part XXX in the series of Azinyl Sulfides. 相似文献
994.
Krystian Pluta Andrzej Maślankiewicz Tadeusz Głbwiak 《Journal of chemical crystallography》1993,23(4):285-290
The title compound (C20H16N2S3) is triclinic, witha=9.494(3)b=9.890(3),c=19.456(5)Å,a=90.26(3)°,°=100.47(3)°, =99.18(3)°,Z=4 and space groupP¯1. The structure was solved by direct methods and refined toR=0.045 for 6076 reflections. There are two nonequivalent molecules in the unit cell. Two pairs of sulfur atoms in ortho-positions remain in very close contact. The S-methyl groups are nearly coplanar to the quinoline moieties and turned to the orthoposition, 2. CP MAS spectrum shows two conformers in the solid state but1H and13C NMR spectra in CDCl3 solution show rapid equilibrium of the conformers giving rise to average NMR data.Part XX in the series of Azinyl Sulfides. 相似文献
995.
Nitrato complexes of copper(II) with 1-ethoxymethyl- imiazole (L), of general formulae CuL2(NO3)2 (1) and CuL4(NO3)2 (2) have been prepared and characterized by elemental analysis and by i.r., f.i.r., vis-n.i.r. spectral evidence, conductivity, magnetochemical measurements and single crystal X-ray analysis. Compound (1) has two 1-ethoxymethylimidazole molecules and two bidentate nitrato groups in the copper(II) co-ordination sphere. In complex (2) the immediate surroundings of copper(II) is described by a tetragonally elongated octahedron with the difference the horizontal and equatorial bond lengths of 0.462 Å. 相似文献
996.
Opial's modulus and fixed points of semigroups of mappings 总被引:3,自引:0,他引:3
Tadeusz Kuczumow 《Proceedings of the American Mathematical Society》1999,127(9):2671-2678
If is a Banach space with the non-strict Opial property and and is a nonempty convex weakly compact subset of , then every semigroup of asymptotically regular selfmappings of with has a common fixed point.
997.
In a series of our previous papers we have investigated the influence of various variables on retention/migration of peptides in various high-performance thin-layer chromatography (HPTLC) and pressurized planar electrochromatography (PPEC) systems. Here we present a correlation of the selectivity of peptide separation in similar, as well as in various HPTLC and PPEC systems investigated before. Our results show that the selectivity in similar HPTLC and PPEC systems is quite different. This results from the share of electrophoresis in separation of solutes by PPEC. The results suggest that combination of HPTLC and PPEC, with properly selected separation conditions (the same, or even better—different for each technique), may be used for efficient two-dimensional separation of peptides. The best separation can be obtained if PPEC is carried out in two opposite directions (toward the cathode and the anode) simultaneously. 相似文献
998.
Amanda Kulpa Jacek Ryl Grzegorz Skowierzak Adrian Koterwa Grzegorz Schroeder Tadeusz Ossowski Pawe Niedziakowski 《Electroanalysis》2020,32(3):588-597
This study describes the synthesis and characterization of ethylenediaminetetraacetic acid (EDTA) functionalized magnetic nanoparticles of 20 nm in size – Fe3O4@SiO2‐EDTA – which were used as a novel magnetic adsorbent for Cd(II) and Pb(II) binding in aqueous medium. These nanoparticles were obtained in two‐stage synthesis: covering by tetraethyl orthosilicate and functionalization with EDTA derivatives. Nanoparticles were characterized using TEM, FT‐IR, and XPS methods. Metal ions were detected under optimized experimental conditions using Differential Pulse Anodic Stripping Voltammetry (DPASV) and Hanging Mercury Drop Electrode (HDME) techniques. We compared the ability of Fe3O4@SiO2‐EDTA to bind cadmium and lead in concentration of 553.9 μg L?1 and 647.5 μg L?1, respectively. Obtained results show that the adsorption rate of cadmium binding was very high. The equilibrium for Fe3O4@SiO2‐EDTA‐Cd(II) was reached within 19 min while for the Fe3O4@SiO2‐EDTA‐Pb(II) was reached within 25 minutes. About 2 mg of nanoparticles was enough to bind 87.5 % Cd(II) and 54.1 % Pb(II) content. In the next step the binding capacity of Fe3O4@SiO2‐EDTA nanoparticles was determined. Only 1.265 mg of Fe3O4@SiO2‐EDTA was enough to bind 96.14 % cadmium ions while 5.080 mg of nanoparticles bound 40.83 % lead ions. This phenomenon proves that the studied nanoparticles bind Cd(II) much better than Pb(II). The cadmium ions binding capacity of Fe3O4@SiO2‐EDTA nanoparticles decreased during storage in 0.5 M KCl solution. Two days of Fe3O4@SiO2‐EDTA storage in KCl solution caused the 32 % increase in the amount of nanoparticles required to bind 60 % of cadmium while eight‐days storage caused further increase to 328 %. The performed experiment confirmed that the storage of nanoparticles in solution without any surfactants reduced their binding capacity. The best binding capacity was observed for the nanoparticles prepared directly before the electrochemical measurements. 相似文献
999.
Dr. Anzhela Galstyan Dr. Yogesh Kumar Maurya Dr. Halina Zhylitskaya Youn Jue Bae Dr. Yi-Lin Wu Prof. Dr. Michael R. Wasielewski Prof. Dr. Tadeusz Lis Prof. Dr. Ulrich Dobrindt Prof. Dr. Marcin Stępień 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(37):8262-8266
Free base, zinc and palladium π-extended porphyrins containing fused naphthalenediamide units were employed as photosensitizers in antimicrobial photodynamic therapy (aPDT). Their efficacy, assessed by photophysical and in vitro photobiological studies on Gram-positive bacteria, was found to depend on metal coordination, showing a dramatic enhancement of photosensitizing activity for the palladium complex. 相似文献
1000.
The main advantage of the application of cyclic chronopotentiometry (CCP) in end-column CE detection arises from the fact that the detection parameters and the magnitude of the analytical signal are (in contrast with other electrochemical detection methods) independent of the ohmic polarization of the solution caused by the separation current at the detection end of the capillary. CCP was used to determine sugars on platinum and gold microelectrodes after separation by CE. The results obtained with a gold microelectrode were better. Subsequently this detection method was used for quantitative determination of sugars in honeys and for their authentication. 相似文献