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41.
Lluís Bosch Ionela Cialîcu Joaquim Caner Xavier Ariza Anna M. Costa Montserrat Terrazas Jaume Vilarrasa 《Tetrahedron letters》2012,53(11):1358-1362
Pd-catalysed reactions of 2-Cl, 2-Br and 2-I derivatives of a 6-chloropurine nucleoside with benzamide have been compared, using Pd2dba3, Xantphos and Cs2CO3 in toluene, between 20 and 80 °C. The reactivity order was 2-I > 2-Br > 6-Cl ? 2-Cl. The 2-I substituent could be replaced even at 0 °C, under conditions disclosed here for the first time. On the other hand, the replacement of the chlorine atom at position 2 (2-Cl) required 110 °C. 相似文献
42.
43.
Building-up a detailed kinetic model for drug release from various supports is a difficult task, especially when chemical
reactions take place, accompanied by adsorption-desorption and diffusion steps. Often, semi-empirical release models derived
from theoretical formulations of the transport process and system characteristics are employed. Their parameters have limited
validity as they are dependent on the support, drug-ligand properties, and release conditions. However, they are often used
for a quick simulation and design of drug delivery systems with a controlled release correlating the model parameters with
the system characteristics and release conditions. Detailed information allows elaboration of an extended mechanistic model;
the bias in the predictions introduced on various levels of model simplification is presented in this paper. A case study
of a chemically activated ligand release in human plasma from a multivalent dendrimeric support is approached, pointing out
the imprecision introduced by the gradual simplification of an extended model as well as the low reliability of the prediction
when using various semi-empirical global models. 相似文献
44.
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
45.
Ilya Razdolski Ruslan R. Subkhangulov Diana G. Gheorghe Francis Bern Ionela Vrejoiu Alexey V. Kimel Andrei Kirilyuk Michael Ziese Theo Rasing 《固体物理学:研究快报》2015,9(10):583-588
Laser‐induced magnetisation dynamics of a La0.7Sr0.3MnO3/SrRuO3 superlattice is studied by means of a single‐colour optical pump‐probe technique. Significant differences in the magnetisation dynamics of a superlattice with respect to the single layers of constituent materials are demonstrated. Below the Curie temperature TC of SrRuO3, laser‐induced ultrafast demagnetisation is found to be followed by a uniform precession of the magnetisation around its new equilibrium. The data is described within a simple model based on a displacive excitation of a precessional magnetisation dynamics. The model is shown to give a good fit to the experimental data. As the initial temperature approaches TC, the oscillations get suppressed and eventually vanish. The magnetisation dynamics is shown to depend on whether the two distinct magnetisation vectors in the superlattice are ferromagnetically or antiferromagnetically aligned. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
46.
Ana Maria Popescu Elena Ionela Neacşu Kazimir Yanushkevich Virgil Constantin 《Surface and interface analysis : SIA》2014,46(6):378-386
Electroless Zn–Ni–P thin films were deposited on low carbon steel from an alkaline non‐cyanide aqueous electrolyte. The newly developed ternary alloys structure and microstructure investigations were carried out via X‐ray diffraction and SEM. Chemical composition of the coatings was investigated via energy dispersive spectroscopy. Polarization tests were used to study the corrosion properties of the coatings in a 3.5 wt.% NaCl solution. The results confirmed the high corrosion resistance of Zn–Ni–P alloy plated steel sheet. The surface analysis of the thin film samples before and after corrosion was performed by XPS. The incorporation of Zn in Ni–P thin film is proven for all initial samples to be as a mixture of zinc and zinc oxide, while nickel exists in +2 and +3 oxidized states. A passive film of a mixture of oxide and hydroxide of zinc and nickel forms on the surface and prevents the Zn–Ni–P thin films from corrosion. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
47.
Rates for two-electron, one-photon Kαα and one-electron, one-photon (hypersatellite) Khα transitions have been calculated within the single-configuration Hartree-Fock model for N, Ne, Al, Ca, Fe and Ni. The initial configuration considered is that of the neutral atom with two electrons missing in the K shell. 相似文献
48.
Francis Bern Michael Ziese Kathrin Dörr Andreas Herklotz Ionela Vrejoiu 《固体物理学:研究快报》2013,7(3):204-206
High quality orthorhombic and tetragonal SrRuO3 thin films were grown by pulsed laser deposition on SrTiO3(001) and Ba0.75Sr0.25TiO3 buffered LaAlO3(001) substrates. Resistivity vs. temperature curves showed a slope change at a Curie temperature of 147.5 ± 2 K for 40 nm thick films irrespective of crystalline symmetry. The Hall resistivity of both films contained an anomalous Hall contribution. The anomalous Hall coefficient was positive throughout the whole temperature range for the tetragonal film, whereas it showed a sign change at 143 K for the orthorhombic film. This is a strong indication that the Berry‐phase mechanism is the dominant anomalous Hall effect mechanism in SrRuO3. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
49.
G. Gavrila K. Godehusen C. Weniger E. T. J. Nibbering T. Elsaesser W. Eberhardt P. Wernet 《Applied Physics A: Materials Science & Processing》2009,96(1):11-18
A time-resolved X-ray absorption study of the structural dynamics of liquid water on a picosecond timescale is presented.
We apply femtosecond midinfrared pulses to resonantly excite the intramolecular O–H stretching band of liquid water and monitor
the transient response in the oxygen K-edge absorption spectrum with picosecond X-ray pulses. In this way, structural changes
in the hydrogen bond network of liquid water upon an ultrafast temperature jump of approximately 20 K are investigated. The
changes of the X-ray absorption as induced by such a temperature jump are about 3.2%. This demonstrates that our method serves
as a sensitive probe of transient structural changes in liquid water and that combined infrared-laser–synchrotron experiments
with substantially shorter X-ray pulses, such as generated with a femtosecond slicing scheme, are possible. 相似文献
50.
Ana Maria POPESCU Kazimir YANUSHKEVICH Vasile SOARE Cristina DONATH Elena Ionela NEACSU Virgil CONSTANTIN 《高等学校化学研究》2018,34(1):113-118
The recovery of metals from a multi-component alloy obtained by crushing, melting and anodic dissolution of waste from electric and electronic equipment(WEEE) was investigated. The anodic dissolution of the alloy was carried out in an electrolysis cell with one copper cathode and a central cast anode, immersed in the electrolyte formed by choline chloride-ethylene glycol-iodine. The temperature of the electrolyte during the process was 343 K. Depending on the electrolysis parameters(current density and cell voltage), cathodic deposits of Sn, Pb and Zn of >99% purity were obtained. Cyclic voltammetry was used in order to determine the deposition potentials of the studied metals. The obtained metallic deposits were subject of determination of XRD, SEM/EDX and AFM in order to evidence the deposits structure and morphology. The experiments performed demonstrated the possibility of separating/selective recovery of metals from the multi-component alloy resulted from the waste from electrical and electronic equipment by anodic dissolution in ionic liquids. 相似文献