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41.
Andreea Bodoki Adriana Hangan Luminita Oprean Gloria Alzuet Alfonso Castieiras Joaquín Borrs 《Polyhedron》2009,28(13):2537-2544
Ternary copper(II) complexes (1–3) of 1,10-phenanthroline and ethylenediamine-R-sulfonamide derivatives (R = benzene, toluene and naphthalene rings) have been synthesized and characterized with the aid of X-ray diffraction and spectroscopic and electrochemical techniques. The crystal structures of the complexes show that the coordination polyhedron around copper(II) is distorted square planar. Both 1,10-phenanthroline and ethylenediamine-R-sulfonamide act as bidentate ligands. The three structures are stabilized by π–π stacking interactions. The interaction of the complexes with calf thymus DNA has been investigated by thermal denaturation studies which indicated that DNA was stabilized in the presence of the compounds. The increase in DNA stability induced by the complexes follows the order: 3 > 2 > 1. All three complexes were found to be very efficient agents of plasmid DNA cleavage in the presence of ascorbate as reducing agent. Mechanistic studies of the DNA cleavage process performed with radical scavengers show that the reactive oxygen species involved in the DNA damage are the hydroxyl radical, singlet oxygen-like species, the superoxide* and hydrogen peroxide. 相似文献
42.
The charge density effect on the behavior of some cationic polysaccharides in aqueous and nonaqueous (methanol) solutions was studied by viscometric and conductometric measurements. The polyelectrolytes investigated contain quaternary ammonium salt groups, N-alkyl-N,N-dimethyl-2-hydroxypropylene ammonium chloride, attached to a dextran backbone. This new class of polyelectrolytes has various linear charge density parameters, xi, located below and above the critical threshold value of counterions condensation, xi(c)=1(xi=0.25-3.18). The viscometric data revealed that all copolymers exhibit a polyelectrolyte behavior and were plotted in the terms of Rao equation. The conductometric measurements of solutions of these copolymers were presented as a function of polymer concentration and charge density. The results were analyzed within the Manning's theory and lower experimental values of the equivalent conductivity than the theoretical ones were found. Possible reasons of this discrepancy have been discussed. The interaction parameters were evaluated and these were found to depend on both the polymer concentration and the charge density. The conductometric behavior of these cationic polysaccharides has shown that counterion condensation is not a threshold phenomenon, their association to the charged groups of the polyions taking place for xi>1 as well as xi<1. 相似文献
43.
Scientific investigations of the Imperial Gates from the Petrindu wooden church,Salaj County,Romania
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Olivia Florena Marutoiu Ioan Bratu Constantin Marutoiu Dana Luminita Postolache Mihai Dragomir Claudiu Tanaselia Sorina Garabagiu 《X射线光谱测定》2018,47(2):176-185
In order to preserve and restore the Imperial Gates from the Petrindu wooden church, Salaj County, Romania, (map location—latitude, longitude: 46.97, 23.19), the scientific investigation of the wooden support and painting materials (ground and pigments) was performed, employing Fourier‐transform infrared spectroscopy (FTIR), X‐ray fluorescence spectroscopy, and 3D scanning. FTIR spectroscopy offered information about the wooden degradation stage, whereas X‐ray fluorescence and FTIR spectroscopic methods were employed for structural painting materials characterization. The structural data can be correlated with the artistic, theological, and historical analysis of this religious patrimony object. After obtaining information about the wooden support and painting materials, the Imperial Gates were 3D digitized using state of the art laser scanning technology. The digital 3D model obtained was restored in a virtual environment and converted into an interactive 3D model that can be used for Romanian cultural heritage digital dissemination. 相似文献
44.
Dr. Régis Y. N. Gengler Prof. Dr. Dimitrios Gournis Akfiny H. Aimon Dr. Luminita M. Toma Prof. Dr. Petra Rudolf 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(24):7594-7600
Much of the research effort concerning the nanoscopic properties of clays has focused on its mechanical applications, for example, as nanofillers for polymer reinforcement. To broaden the horizon of what is possible by exploiting the richness of clays in nanoscience, herein we report a bottom‐up approach for the production of hybrid materials in which clays act as the structure‐directing interface and reaction media. This new method, which combines self‐assembly with the Langmuir–Schaefer technique, uses the clay nanosheets as a template for the grafting of C60 into a bi‐dimensional array, and allows for perfect layer‐by‐layer growth with control at the molecular level. In contrast to the more‐common growth of C60 arrays through nanopatterning, our approach can be performed under atmospheric conditions, can be upscaled to areas of tenths of cm2, and can be applied to almost any hydrophobic substrate. Herein, we report a detailed study of this approach by using temperature‐dependent X‐ray diffraction, spectroscopic measurements, and STM. 相似文献
45.
The purpose of this article is to emphasize that new nanomaterials offer a number of attractive alternatives for solar energy
use in wastewater photocatalysis. The wastewater from the textile industry contains dyes and heavy metals. Thin films of cadmium
doped TiO2 (Cd-TiO2) were coated by a doctor blade using TiO2 Degussa P25 and cadmium precursor (cadmium nitrate). The photocatalytic efficiency of cadmium doped TiO2 is strongly influenced by crystal structure, particle size, particle morphology, porosity and doping. The pore size distribution
and the roughness analysis have been studied by the atomic force microscopy (AFM) of the thin films. The photocatalytic activity
of the samples was tested in Methyl orange and Methylene blue photodegradation. Cadmium doped TiO2 catalyst does not significantly decrease the efficiency of photodegradation processes, and, in some situations, improves
dye photodegradation. 相似文献
46.
Image Restoration and Decomposition via Bounded Total Variation and Negative Hilbert-Sobolev Spaces 总被引:4,自引:0,他引:4
We propose a new class of models for image restoration and decomposition by functional minimization. Following ideas of Y.
Meyer in a total variation minimization framework of L. Rudin, S. Osher, and E. Fatemi, our model decomposes a given (degraded
or textured) image u
0 into a sum u+v. Here u∈BV is a function of bounded variation (a cartoon component), while the noisy (or textured) component v is modeled by tempered distributions belonging to the negative Hilbert-Sobolev space H
−s
. The proposed models can be seen as generalizations of a model proposed by S. Osher, A. Solé, L. Vese and have been also
motivated by D. Mumford and B. Gidas. We present existence, uniqueness and two characterizations of minimizers using duality
and the notion of convex functions of measures with linear growth, following I. Ekeland and R. Temam, F. Demengel and R. Temam.
We also give a numerical algorithm for solving the minimization problem, and we present numerical results of denoising, deblurring,
and decompositions of both synthetic and real images. 相似文献
47.
Maria Zaharescu Maria Crisan Luminita Predoana Mariuca Gartner Dana Cristea Stefania Degeratu Elena Manea 《Journal of Sol-Gel Science and Technology》2004,32(1-3):173-177
In the present work, the influence of substituted Si-alkoxides on the structural and optical properties of films obtained in the SiO2-TiO2 system was studied. Methyltriethoxysilane (MTEOS) and 3-(tri-methoxysilyl)propyl methacrylate (TSPM) were used as SiO2 sources and Ti(OBu)4 was used as TiO2 source. Acetylacetone was added to the Ti(OBu)4 as chelating agent and the synthesis was carried out in acid medium. The films were deposited on oxidized Si-wafers by spin-coating. The films were characterized by XRD, spectro-ellipsometry (SE), and atomic force microscopy (AFM). The results obtained have shown that in the case of hybrid films the desired thickness could be obtained in a single deposition step. The thickness of the films and the optical properties are controlled by the bulkiness of the organic substitute bounded to Si. Among other optical applications, the potential use of such films as optical waveguides is proposed. 相似文献
48.
Oana Carp E. Segal Maria Brezeanu Luminita Patron R. Barjega N. Stanica 《Journal of Thermal Analysis and Calorimetry》1996,47(3):857-869
The authors analyse the possibility of obtaining manganese-zinc ferrite through the transformations of polynuclear coordination compounds (pcc), either in the solid state or in a reaction medium. Polynuclear coordination compound precursors with the general molecular formula: [Fe(II)xFe(III)y(Mn0.5Zn0.5)(C2O4)2(OH)y+2(H2O)2] with 0.2相似文献
49.
Claudia Maria Simonescu V. S. Teodorescu Oana Carp Luminita Patron Camelia Capatina 《Journal of Thermal Analysis and Calorimetry》2007,88(1):71-76
Thermal behaviour of CuS (covellite) obtained from the Cu(CH3COO)2·H2O and Na2S2O3·5H2O
system, working at different molar ratio (1:6 and 1:4) in presence/absence
of NH4VO3, was studied. It was
established that the presence of vanadium in the system induces a densification
of CuS nodules, but do not change the hexagonal CuS structure. It has an important
influence in thermal behaviour of copper sulfide CuS obtained also. The morphological
characteristics of CuS play an important role in the thermal stability and
the stoichiometry of the thermal decompositions.
Also, the possibility
to obtain copper sulfides with greater cooper content was investigated. 相似文献
50.
P. Budrugeac Alice Luminita Petre E. Segal 《Journal of Thermal Analysis and Calorimetry》1996,47(1):123-134
The validity of isoconversional methods used to evaluate the activation energy is discussed. The authors have shown that the Flynn-Wall-Ozawa and Friedman methods give results that agree with each other only if the activation energy does not change with the degree of conversion. A criterion for the reaction mechanism as expressed by the differential conversion function is suggested too. 相似文献