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371.
Maria Balcerzak Maria Kopacz Anna Kosiorek Elzbieta Swiecicka Stanis?aw Kus 《Analytical sciences》2004,20(9):1333-1337
Results of some studies on the interaction of noble metals with quercetin (Q) and quercetin-5'-sulfonic acid (QSA), the compounds of flavonoid group, are presented. The reactions of chloride complexes of the metals: RuOHCl5(2-), PdCl4(2-), OsCl6(2-), PtCl6(2-) and AuCl4- with both reagents were examined. The redox reactions of ruthenium and gold with Q and QSA have been identified. The reaction of the metals with both reagents results in the formation of the oxidized form of Q that exhibits maximum absorbance at 291 nm. Ruthenium and gold react with the examined reagents under similar conditions: 0.04 M HCl and 1 x 10(-4) M Q (or QSA). The CH3OH + H2O (1:1) (Q) and pure aqueous (QSA) media can be used. The reaction of gold with Q is slow at room temperature. It can be accelerated by heating the solution being examined. The reaction proceeds significantly faster when the water-soluble sulfonic derivative of quercetin, quercetin-5'-sulfonic acid, is used as a reagent. The new species formed can make the basis of spectrophotometric methods for the determination of ruthenium and gold. The molar absorptivities at 291 nm are equal to 5.0 x 10(3) and 2.2 x 10(4) L mol(-1) cm(-1) for Ru and Au, respectively, independently of the reagent used. Some methods for the determination of the content of gold (0.04%) in a cosmetic cream were developed. 相似文献
372.
We present a fit to spin asymmetries which gives polarized quark distributions. These functions are closely related to the
ones given by the Martin, Roberts and Stirling fit for unpolarized structure functions. The integrals of polarized distributions
are discussed and compared with the corresponding quantities obtained from neutron and hyperonβ-decay data. We use the combination of proton, neutron and deuteron spin asymmetries in order to determine the coefficients
of our polarized quark distributions. Our fit shows that phenomenologically there is no need for taking polarized gluons into
account.
Work supported in part by the KBN-Grant 2-P302-143-06 相似文献
373.
374.
Stanisław Janeczko Jacek Komorowski Tadeusz Mostowski 《Reports on Mathematical Physics》1985,21(3):357-381
This paper is devoted to the investigation of critical phenomena from the mathematical point of view. An interesting question in this field is universality (i.e. independence of the type of material and, to some extent, of the type of process) of the so-called critical exponents. We try to show that one can compute the critical exponents using structural stability arguments. The universality is then implied automatically as a consequence of similarity of models and of the structure of stable singularities. The considerations lead to some new results: information about the generic shape of hysteresis loops and universal form of the equation of state in the critical region. 相似文献
375.
Enantiomerically pure bidentate heteroorganic ligands built on an achiral skeleton containing hydroxyl and aziridine moieties as nucleophilic centers, capable of binding various organometallic reagents, have proven to be highly efficient catalysts in the enantioselective addition of diethylzinc and phenylethynylzinc to aryl and alkyl aldehydes to give the desired chiral products in high chemical yields (up to 90%) and with ees of up to 95%. The influence of the stereogenic center located in the carbon atom in the aziridine moiety on the stereochemical course of the reaction is reported. 相似文献
376.
Reactions of (R)-2,3-O-isopropylideneglyceraldehyde with 2-methylfuran under high pressure and with lithium derivative of 2-methylfuran under atmospheric pressure are studied and the stereochemical models involving coordinating interactions between the metal cation and oxygen atoms of the aldehyde are discussed. 相似文献
377.
Stanisław Zieliński Lechosław Łomozik Bogumiła Antczak-Kupracz 《Microchemical Journal》1983,28(1):1-9
A method of simultaneous determination of heavy and light lanthanides has been described. In the first stage, the total amount of rare earth elements is determined (complexometrically with EDTA as a titrant and MTB as an indicator, pH = 5.5). Then, on the basis of the proportional relationship between absorbance and molar ratio of the system, concentration of each component is calculated (using the measured absorbance of the system and “the absorbance of the standard” taken from the standard calibration curves). The applicability of the method is limited by r.e.e. concentration equal to 3 × 10?5M. In the case when the content of one of the metals amounts to at least 15% of their sum, the relative error of determination does not exceed 2%.Results of the determination for selected pairs of lanthanides are presented together with a statistical estimation of errors. 相似文献
378.
The phototoxicity of two new porphyrin photosensitizers, diarginine diprotoporphyrinate (PP(Arg)2) and N,N-diphenylalanyl protoporphyrin (PP(Phe)2), and the synergistic effect of 5-methoxyposralen (5-MOP) have been studied in comparison with that of protoporphyrin IX (PPIX). Under ultraviolet-A (UV-A) irradiation (lambda=365 nm), the phototoxicity of the porphyrins toward cultured human fibroblasts and keratinocytes decreases in the order: PPIX > PP(Arg)2 > PP(Phe)2. A synergistic effect of 5-MOP on the phototoxicity of PPIX, PP(Arg)2 and PP(Phe)2 has been observed. The combination of PPIX, PP(Arg)2 and PP(Phe)2 with 0.1-0.5 microM 5-MOP significantly potentiates the phototoxicity of the three porphyrins. The most effective potentiation was observed with the water-soluble PP(Arg)2 and 5-MOP concentrations lower than 0.75 microM. Above this 5-MOP concentration this potentiation is abolished. The intracellular concentration of PPIX and PP(Phe)2 is independent of the presence of 5-MOP. On the other hand, the intracellular content of PP(Arg)2 is decreased in a concentration-dependent manner by the psoralen. Illumination with red light, not absorbed by 5-MOP, leads to a weak potentiation of the PP(Arg)2 phototoxic effect in the presence of 5-MOP, suggesting that dark interaction of 5-MOP with cell membranes aggravated by porphyrin photosensitization is involved in the observed phenomena. The results are tentatively explained by differences in hydrophobicity and molecular structures of the examined photosensitizers. PPIX, which is barely soluble in water, has a significantly higher affinity for cell membranes and simultaneously exerts a stronger phototoxic effect than PP(Arg)2 whose solubility in water is high. On the other hand, the weak phototoxicity of PP(Phe)2 could be explained by the steric hindrance brought by the phenylalanyl substituents on the pyrrole ring. The loss in the PP(Arg)2 cell content probably explains the inhibition of the synergistic effect of 5-MOP on the PP(Arg)2 phototoxicity at high 5-MOP concentration. This study suggests that PP(Arg)2 in combination with 5-MOP might reveal a strong phototoxic effect when applied to skin cancer treatment. 相似文献
379.
The intermediate Hamiltonian Fock-space coupled-cluster (FS-CC) method with singles and doubles is applied to calculate vertical excitation energies (EEs) for some molecular systems. The calculations are performed for several small molecules, such as H2O, N2, and CO, and for larger systems, such as C2H4, C4H6, and C6H6. Due to the intermediate Hamiltonian formulation, which provides a robust computational scheme for solving the FS-CC equations, and the efficient factorization strategy, relatively large basis sets and model spaces are employed permitting a comparison of the calculated vertical EEs with the experimental data. 相似文献
380.
Anna Wojciechowska Lechosław Łomozik Stanisław Zieliński 《Monatshefte für Chemie / Chemical Monthly》1987,118(12):1317-1324
The composition and stability of La3+, Pr3+ and Lu3+ complexes with aspartic acid and asparagine were analysed. The formation of complexes of the typeML andMHL was determined for La3+ and Pr3+ with aspartic acid, and of the typeMHL for Lu3+ with aspartic acid. For La3+, Pr3+ and Lu3+ with asparagine the formation ofML(OH) complexes was observed. By means of1H NMR and13C NMR studies the participation in the coordination of both -COOH groups was determined for aspartic acid, whereas for asparagine the participation of the -COOH group was determined in complexes with La3+, Pr3+, and of the -COOH and the -NH2 groups in the complex with Lu3+.
Potentiometrische und spektroskopische Untersuchungen an La(III), Pr(III) und Lu(III)-Komplexen von Asparaginsäure und Asparagin
Zusammenfassung Die Zusammensetzung und die Stabilität von La3+, Pr3+ und Lu3+-Komplexen mit Asparaginsäure und Asparagin wurden untersucht. Es wurde die Bildung von La3+ und Pr3+-Komplexen des TypsML undMHL, und ein Lu3+-Komplex des TypsMHL mit Asparaginsäure festgestellt. Für diese drei Lanthaniden wurde auch die Bildung von Komplexen des TypsML(OH) mit Asparagin beobachtet. Mit Hilfe von1H-NMR und13C-NMR-Untersuchungen wurde für Asparaginsäure die Teilnahme der beiden -COOH-Gruppen, für Asparagin die Teilnahme der -COOH-Gruppe in den Komplexen mit La3+, Pr3+ und der-COOH und -NH2-Gruppen in dem Komplex mit Lu3+ an der Koordinierung festgestellt.相似文献