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101.
An integral representation for an arbitrary bounded operator T defined on a Hilbert space ${\mathcal{H}}$ is given. The representing measure is in general defined on a Jordan curve surrounding the spectrum of T. It is obtained as a limit, in a certain weak sense, of a family (F r ) of absolutely continuous measures the Radon?CNikodym derivative of which (with respect to the standard Lebesgue measure on the considered Jordan curve) are described explicitly in terms of the operator T and its adjoint T *. 相似文献
102.
Höckendorf RF Hao Q Sun Z Fox-Beyer BS Cao Y Balaj OP Bondybey VE Siu CK Beyer MK 《The journal of physical chemistry. A》2012,116(15):3824-3835
The chemistry of (H(2)O)(n)(?-), CO(2)(?-)(H(2)O)(n), and O(2)(?-)(H(2)O)(n) with small sulfur-containing molecules was studied in the gas phase by Fourier transform ion cyclotron resonance mass spectrometry. With hydrated electrons and hydrated carbon dioxide radical anions, two reactions with relevance for biological radiation damage were observed, cleavage of the disulfide bond of CH(3)SSCH(3) and activation of the thiol group of CH(3)SH. No reactions were observed with CH(3)SCH(3). The hydrated superoxide radical anion, usually viewed as major source of oxidative stress, did not react with any of the compounds. Nanocalorimetry and quantum chemical calculations give a consistent picture of the reaction mechanism. The results indicate that the conversion of e(-) and CO(2)(?-) to O(2)(?-) deactivates highly reactive species and may actually reduce oxidative stress. For reactions of (H(2)O)(n)(?-) with CH(3)SH as well as CO(2)(?-)(H(2)O)(n) with CH(3)SSCH(3), the reaction products in the gas phase are different from those reported in the literature from pulse radiolysis studies. This observation is rationalized with the reduced cage effect in reactions of gas-phase clusters. 相似文献
103.
Monica Boriceanu Marius Bota Adrian Petruşel 《Central European Journal of Mathematics》2010,8(2):367-377
Fractals and multivalued fractals play an important role in biology, quantum mechanics, computer graphics, dynamical systems,
astronomy and astrophysics, geophysics, etc. Especially, there are important consequences of the iterated function (or multifunction)
systems theory in several topics of applied sciences. It is known that examples of fractals and multivalued fractals are coming
from fixed point theory for single-valued and multivalued operators, via the so-called fractal and multi-fractal operators.
On the other hand, the most common setting for the study of fractals and multi-fractals is the case of operators on complete
or compact metric spaces. The purpose of this paper is to extend the study of fractal operator theory for multivalued operators
on complete b-metric spaces. 相似文献
104.
Mihaela Badea Petru Budrugeac Andrei Cucos Eugen Segal 《Journal of Thermal Analysis and Calorimetry》2014,115(2):1999-2005
The thermal stability and the decomposition steps of bis(pyridine)manganese(II) chloride (Mn(py)2Cl2) were determined by thermogravimetry and derivative thermogravimetry. The initial compound and the solid compounds resulted from each step of decomposition were characterized by FT-IR spectroscopy and RX diffraction. It was pointed out that at the progressive heating of Mn(py)2Cl2, the following decomposition reactions occur: I $$ {\text{Mn}}\left( {\text{py}} \right)_{ 2} {\text{Cl}}_{ 2} \left( {\text{s}} \right) \, \to {\text{ Mn}}\left( {\text{py}} \right){\text{Cl}}_{ 2} \;\left( {\text{s}} \right) \, + {\text{ Py }}\left( {\text{g}} \right) $$ II $$ {\text{Mn}}\left( {\text{py}} \right){\text{Cl}}_{ 2} \left( {\text{s}} \right) \, \to {\text{ Mn}}\left( {\text{py}} \right)_{ 2/ 3} {\text{Cl}}_{ 2} \;\left( {\text{s}} \right) \, + { 1}/ 3 {\text{ Py }}\left( {\text{g}} \right) $$ III $$ {\text{Mn}}\left( {\text{py}} \right)_{ 2/ 3} {\text{Cl}}_{ 2} \left( {\text{s}} \right) \, \to {\text{ MnCl}}_{ 2} \left( {\text{s}} \right) \, + { 2}/ 3 {\text{ Py }}\left( {\text{g}} \right) $$ The dependence of the activation energy of these decompositions steps on the conversion degree, evaluated by isoconversional methods, shows that all decomposition reactions are complex. The mechanism and the corresponding kinetic parameters of reaction (I) were determined by multivariate non-linear regression program and checked for quasi-isothermal data. It was pointed out that the reaction (I) consists of three elementary steps, each step having a specific kinetic triplet. 相似文献
105.
Short‐term UV‐B Dose Stimulates Production of Protective Metabolites in Matricaria chamomilla Leaves
Veronika Petruľová Zuzana Dučaiová Miroslav Repčák 《Photochemistry and photobiology》2014,90(5):1061-1068
Physiological response of two cultivars of Matricaria chamomilla plants on UV irradiation was studied. The impact of used short‐time UV dose was evaluated in three time points; 2, 24 and 48 h after irradiation. Used UV irradiation immediately resulted in changes in plant oxidative status monitored as increased concentration of H2O2. Decrease in chlorophyll a and b indicated the impact on photosynthetic apparatus. For phenolic secondary metabolites, an increase in total soluble phenols and AlCl3‐reactive flavonols was observed. The activity of main phenolic enzyme, phenylalanine ammonia‐lyase, increased with time after irradiation. Significant changes, mainly decreasing trends, in the content of free coumarins and their glycosidic precursors were observed. Enhanced accumulation in chlorogenic and 1,5‐dicaffeoylquinic acid and in (Z)‐isoform of dicycloethers was detected. From these results, the redirecting precursors of coumarin biosynthesis to biosynthesis of substances with higher antioxidative potential can be assumed. Different reactions in diploid and tetraploid plants were recorded, too. 相似文献
106.
Traian Florin Marinca Bogdan Viorel Neamţu Ionel Chicinaş Petru Pascuta 《Journal of Thermal Analysis and Calorimetry》2014,118(2):1245-1251
Commercially, iron (α-Fe) and hematite (α-Fe2O3) powders were used for the synthesis of composite powders of Fe2O3/Fe type by mechanical milling. Several ratios of Fe2O3/Fe were chosen for the composite synthesis; the atomic percent of oxygen in the starting mixtures ranged from 21 to 46 %. The Fe2O3/Fe composite samples with various Fe/O ratios were milled for different milling times. The milled composite samples were subjected to the heat treatments in argon up to 900 °C. During the heat treatment at temperatures that do not exceed 550 °C, Fe3O4/Fe composite particles are formed by the reaction between the Fe2O3 and Fe. Further increase of the heat treatment up to 700 °C leads to the reaction of the Fe3O4/Fe composite component phases, resulting thus in the formation of FeO/Fe composite. The heat treatment up to 900 °C of the Fe2O3/Fe leads to the formation of a composite of FeO/Fe3O4/Fe independent of the milling time and Fe2O3/Fe ratios. The onset temperatures of the Fe3O4 and FeO formations decrease upon increasing the milling time. Another important aspect is that, in the case of the same milling time but with a large amount of iron into the composite powder the formations temperatures of Fe3O4 and FeO are also decreasing. The influence of the mechanical activation time, heat treatment temperature, and Fe/O ratio on the formation of the (Fe3O4, FeO)/Fe composite from Fe2O3+Fe precursor mixtures was studied by differential scanning calorimetry and X-ray diffraction techniques. 相似文献
107.
108.
Duy-Phong Pham-Huu Mária Petrušová James N. BeMiller Ladislav Petruš 《Journal of carbohydrate chemistry》2013,32(1):93-110
ABSTRACT Treatment of per-O-acetylated or acetalated glycosylnitromethanes derived from the common hexoses and pentoses with tributyltin hydride and a catalytic amount of a radical initiator [1,1′-azobis(cyclohexanecarbonitrile)] in refluxing benzene easily afforded the corresponding glycosylmethanal oximes in 84-97% yields. Per-O-acetylated C-β-glycopyranosylmethanal oximes were employed for synthesis of versatile C-β-glycopyranosyl cyanides of the β-D-gluco, β-D-manno, β-D-galacto, β-D-xylo, and β-L-rhamno configurations. 相似文献
109.
110.
We present a generalized operator range construction associated to an indefinite unbounded selfadjoint operator that yields
closed embeddings of Kreĭn spaces. As an application we obtain an energy space representation, in the sense of Friedrichs,
of a general free Dirac operator. 相似文献