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191.
Dr. Maria Angela Castriciano Dr. Mario Samperi Dr. Salvatore Camiolo Dr. Andrea Romeo Prof. Luigi Monsù Scolaro 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(36):12161-12168
The binding of a tetracationic porphyrin to a highly charged polymer like poly(sodium vinylsulfonate) has been investigated over a wide pH range and under various experimental conditions. We present evidence that, depending on the pH, the high electrostatic field exerted by the polymer stabilizes the diprotonated form of the free base porphyrin at unusual pH values or otherwise causes the formation of H‐type aggregates. In particular, at a low polymer concentration, lowering the pH at first allows the formation of the diacid species then it determines its reorganization in close‐packed J‐type aggregates. The employment of various metallo‐derivatives of the title porphyrin enables a better insight into the nature of all the detected species. 相似文献
192.
Marian Romeo Calin Alexandru Erminiu Druker Ileana Radulescu 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(1):283-288
This paper presents a method for efficiency calibration of a measuring alpha–beta system PROTEAN ORTEC, MPC-2000-DP, using standard radioactive sources. The system is used to measure gross alpha–beta activity concentrations in environmental samples. The calculated efficiencies of detection were subsequently introduced in the system for two working geometries: measuring geometry—gross alpha–beta $ \varepsilon_{\alpha }^{g} $ = 31,37 ± 0.25 (%)—the alpha efficiency and $ \varepsilon_{\beta }^{g} $ = 44.94 ± 0.69 (%)—the beta efficiency, where the spillover factor is $ X_{\text{talk}}^{g} $ = 25.59 ± 0.50 (%) and measuring geometry up alpha–beta $ \varepsilon_{\alpha }^{u} $ = 36.23 ± 0.29 (%)—the alpha efficiency and $ \varepsilon_{\beta }^{u} $ = 48.53 ± 0.74 (%)—the beta efficiency, where the spillover factor is $ X_{\text{talk}}^{u} $ = 31.08 ± 0.60 (%). 相似文献
193.
194.
In the last years, new variants of the minimum cycle basis (MCB) problem and new classes of cycle bases have been introduced, as motivated by several applications from disparate areas of scientific and technological inquiries. At present, the complexity status of the MCB problem has been settled only for undirected, directed, and strictly fundamental cycle bases.In this paper, we offer an unitary classification accommodating these three classes and further including the following four relevant classes: 2-bases (or planar bases), weakly fundamental cycle bases, totally unimodular cycle bases, and integral cycle bases. The classification is complete in that, for each ordered pair (A,B) of classes considered, we either prove that A⊆B holds for every graph or provide a counterexample graph for which A?B. The seven notions of cycle bases are distinct (either A?B or B?A is exhibited for each pair (A,B)).All counterexamples proposed have been designed to be ultimately effective in separating the various algorithmic variants of the MCB problem naturally associated to each one of these seven classes. Furthermore, we provide a linear time algorithm for computing a minimum 2-basis of a graph. Finally, notice that the resolution of the complexity status of some of the remaining three classes would have an immediate impact on practical applications, as for instance in periodic railway timetabling, only integral cycle bases are of direct use. 相似文献
195.
196.
A. Noviello F. Romeo R. De Luca 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,50(3):505-511
A model describing the dynamics related to the spreading of non-lethal
infectious diseases in a fixed-size population is proposed. The model
consists of a non-linear delay-differential equation describing the time
evolution of the increment in the number of infectious individuals and
depends upon a limited number of parameters. Predictions are in good
qualitative agreement with data on influenza, which is taken to be a
representative type of non-lethal infectious disease. 相似文献
197.
Romeo Rizzi 《Discrete Mathematics》2002,257(1):177-181
We introduce the notion of T-pairing and give a min-max characterization for the minimum size of a T-cut. We show that the coefficients in the minimal TDI system for the T-cut polyhedron can be arbitrarily big. 相似文献
198.
199.
L. Abate A. Chisari G. Romeo R. Maggiore G. Siracusa 《Journal of Thermal Analysis and Calorimetry》1983,28(2):227-236
The solid-state syntheses of complexes of uranyl acetate dihydrate andN-phenylthiourea have been attempted by heating various stoichiometric mixtures of the reactants directly in a DSC and in a TA apparatus. Both the DSC and the TG results indicate that only the 1∶1 adduct is formed, independently of the molar ratios of the reactants. It appears that the reaction is complete only with a large excess ofN-phenylthiourea, in agreement with IR data. 相似文献
200.
A series of computational approaches, based on the global and local indexes defined in the context of the DFT, at the B3LYP/6-31G(d) computational level, were investigated to elucidate the regiochemistry and the energetics of the mesitonitrile oxide 1,3-dipolar cycloaddition with anthracene and the aza-analogue acridine. The results are in agreement with the observed regioselectivity and are in contrast with the ones predicted in terms of FMO theory. 相似文献