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191.
Tudor Rosu Elena Pahontu Catalin Maxim Rodica Georgescu Nicolae Stanica Gabriela Laura Almajan Aurelian Gulea 《Polyhedron》2010
Coordination compounds of Cu(II), VO(II), Ni(II), and Mn(II) with the Schiff base obtained through the condensation of 4-amino-2,3-dimethyl-1-phenyl-3-pyrazolin-5-one with 3-formyl-6-methyl-chromone were synthesized. The characterization of the newly formed compounds was done by 1H NMR, UV–Vis, IR, ESR spectroscopy, elemental analysis and molar electric conductibility. The crystal structure of 1-phenyl-2,3-dimethyl-4-(N-3-formyl-6-methyl-chromone)-3-pyrazolin-5-one (HL) has been determined by X-ray diffraction studies, as well as the one of its copper(II) complex [CuL(OAc)]·CH3OH which contains an anionic ligand and an acetate in the coordination sphere of the metal. The single crystal X-ray structure for (HL) was analyzed for its various weak H-bonding and dimeric association. 相似文献
192.
Cristina Bogatu Dan Geană Rodica Vîlcu Anca Duţă Wim Poot Theo W. de Loos 《Fluid Phase Equilibria》2010
Vapour–liquid, liquid–liquid and liquid–liquid–vapour equilibria in the binary system consisting of trifluoromethane (refrigerant R23) and 1-phenyloctane were determined in the temperature range T = 250–400 K and at pressures up to 15 MPa. The experiments were carried using a Cailletet apparatus according to the synthetic method. The investigated system exhibits type III phase behaviour according to the classification of van Konynenburg and Scott. Modelling of the equilibrium data was done with the Peng–Robinson (PR) and Soave–Redlich–Kwong (SRK) equations of state coupled with classical van der Waals mixing rules. In order to predict the global phase behaviour of the system, one single set of binary parameters was used. The topology of the phase behaviour was correctly reproduced. 相似文献
193.
194.
Absorption, transmission and reflection properties of hydrogen uranyl phosphate (HUP) are determined, by using pyroelectric (PE) sensors in thermally-coupled (PPE) and thermally-decoupled (conventional) spectroscopy configurations. Absorption bands at 1.25, 1.5 and 2.0μm, stronger for HUP than for the corresponding ammonium salt, have been observed. This can be correlated with the much higher protonic conductivity of HUP and suggests polaronic effects on the conduction mechanism in this solid electrolyte. 相似文献
195.
Giuliano Lazzaroni Riccarda Rossi Marita Thomas Rodica Toader 《Journal of Dynamics and Differential Equations》2018,30(3):1311-1364
We present a model for rate-independent, unidirectional, partial damage in visco-elastic materials with inertia and thermal effects. The damage process is modeled by means of an internal variable, governed by a rate-independent flow rule. The heat equation and the momentum balance for the displacements are coupled in a highly nonlinear way. Our assumptions on the corresponding energy functional also comprise the case of the Ambrosio–Tortorelli phase-field model (without passage to the brittle limit). We discuss a suitable weak formulation and prove an existence theorem obtained with the aid of a (partially) decoupled time-discrete scheme and variational convergence methods. We also carry out the asymptotic analysis for vanishing viscosity and inertia and obtain a fully rate-independent limit model for displacements and damage, which is independent of temperature. 相似文献
196.
Ligia Munteanu Cornel Brişan Veturia Chiroiu Dan Dumitriu Rodica Ioan 《Nonlinear dynamics》2014,78(3):1877-1889
The present paper points out the scenario of the hyperchaotic attractor formation (an attractor with at least two positive Lyapunov exponents) in a class of models governed by the Sommerfeld effects. The Sommerfeld effect is the result of the conservation law of energy. When a dynamical system is coupled to a power source, it acts like a energy sink for which a part of the source energy is spend to deform the system rather than increasing the drive speed. The Sommerfeld effect involves riddling bifurcation which explains the creation of the hyperchaotic attractor. 相似文献
197.
Ionela Alan Angela Kriza Mihaela Badea Nicolae Stanica Rodica Olar 《Journal of Thermal Analysis and Calorimetry》2013,111(1):483-490
New complexes of type [M(HL)(CH3COO)(OH2)m]·nH2O (where M:Co, m = 2, n = 2; M:Ni, m = 2, n = 1.5; M:Zn, m = 0, n = 2.5 and M:Cd, m = 0, n = 0; H2L:5-bromo-N,N′-bis-(salicylidene)-o-tolidine) have been synthesized and characterized by microanalytical, IR, UV–Vis-NIR and magnetic data. Electronic spectra of Co(II) and Ni(II) complexes are characteristic for an octahedral stereochemistry. The IR spectra indicate a chelate coordination mode for mono-deprotonated Schiff base and a bidentate one for acetate ion. The thermal transformations are complex according to TG and DTA curves including dehydration, acetate decomposition and oxidative degradation of the Schiff base. The final product of decomposition is the most stable metallic oxide. 相似文献
198.
Josef Pola Zdenk Bastl Vladimír Vorlí
ek Florian Dumitrache Rodica Alexandrescu Ion Morjan Ion Sandu Victor Ciupina 《应用有机金属化学》2004,18(7):337-342
The IR laser irradiation of a gaseous mixture of iron pentacarbonyl–methoxytrimethylsilane–ethene in argon induces ethene‐photosensitized decomposition of iron pentacarbonyl into elemental iron and decomposition of methyltrimethoxysilane into species that polymerize into methylmethoxysilicone. These two concurrent gas‐phase processes allow formation of iron–iron oxide/methylmethoxysilicone nanocomposite. Spectral analyses and electron microscopy reveal the nanocomposite as consisting of iron clusters oxidized in outer layers and covered with the organosilicon polymer. The procedure shows its potential for gas‐phase synthesis of iron‐based clusters embedded in a polymer matrix. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
199.
Formation of [Bi11]3−, A Homoatomic,Polycyclic Bismuth Polyanion,by Pyridine‐Assisted Decomposition of [GaBi3]2− 下载免费PDF全文
Dipl.‐Chem. Bastian Weinert Armin Rainer Eulenstein Dr. Rodica Ababei Prof. Dr. Stefanie Dehnen 《Angewandte Chemie (International ed. in English)》2014,53(18):4704-4708
Until now, polycyclic bismuth polyanions have not been known—thus discriminating bismuth from its lighter congeners. However, the synthesis of [K([2.2.2]crypt)]3(Bi11)?2 py?tol, allows us to present the first structurally characterized homoatomic, polycyclic bismuth polyanion, which exhibits the [P11]3? “ufosan” structure. It was obtained upon treatment of [K([2.2.2]crypt)]2(GaBi3)?en with the solvent pyridine. The binary Zintl anion [GaBi3]2? decomposes under oxidative coupling of pyridine molecules and release of H2 to form the title compound. The unprecedented reaction, its products and by‐products were investigated by means of spectroscopy, spectrometry, and DFT studies. All findings reveal the specific reaction conditions to be crucial for the formation of the [Bi11]3? ion—and indicate the possibility of the generation and isolation of further, large bismuth polyanions. 相似文献
200.
Christina?Z?laru Claudia?C.?Cri?anEmail author Ioan?C?linescu Zenovia?Moldovan Isabela??arcomnicu Simona?C.?Litescu Rodica?Tatia Lucia?Moldovan Daniel?Boda Mircea?Iovu 《Central European Journal of Chemistry》2014,12(8):858-867
The aim of this research was to investigate the chemical composition of Coreopsis tinctoria Nutt. fruits extract, to highlight the potential of ultrasound assisted extraction in the fast preparation of extracts rich in polyphenols using different solvents (55%, 78% and 96% hydrous ethanol) and to evaluate the antioxidant potential of formulated extracts. LC-MS/MS was used to characterize the ethanolic extract from Coreopsis tinctoria Nutt. dried fruits. The extract contains different flavonoids (marein, flavanomarein, quercetagetin-7-O-glucoside, okanin aurone, leptosidin, luteolin, apigenin) and phenolic acids (chlorogenic acid, caffeic acid). Several parameters that could affect extraction efficiency were evaluated. Finally, this study focused on determination of plant extracts total phenolic content and their antioxidant capacity. The experimental results allowed the selection of the optimum operating parameters leading to the highest total polyphenolic content, expressed as gallic acid equivalents, and avoiding the degradation of phenolic compounds (ethanol 55%; extraction temperature 323.15 K, extraction time 30 min, liquid/solid ratio 20/1). A good relationship between total phenolic content and antioxidant capacity was obtained. 相似文献