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141.
A. Ioachim M.I. Toacsan M.G. Banciu L. Nedelcu F. Vasiliu H.V. Alexandru C. Berbecaru G. Stoica 《Progress in Solid State Chemistry》2007,35(2-4):513-520
Ba1−xSrxTiO3 solid solutions were prepared by solid-state reaction from raw materials. Four compositions with x = 0.25, 0.50, 0.75 and 0.90 have been investigated. The perovskite type and polycrystalline structure of the BST samples were revealed by X-ray diffraction data. The morphology, grain size distribution, porous structure and elemental composition of the sintered ceramics were analyzed by using scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) microanalysis. The temperature dependence of permittivity and of dielectric loss tangent at low frequency (1 kHz) showed decrease of Curie temperature with increase of Sr content. Microwave measurements (1 GHz) showed substantial decrease of the dielectric constant from about 1600 to 200 and also of the losses from 12% to less than 2% with the Sr concentration increase from x = 0.25 to x = 0.90. Moreover, the addition of MgO and MnO2 1 wt.% each, improved sintering process and lowered the microwave losses up to 0.2%. 相似文献
142.
Composite membranes based on gellan and poly(N-vinylimidazole) were prepared by using the method of solvent evaporation. In acid medium ionic interactions are established and evidenced by measurements of FTIR spectroscopy. The properties of these membranes were investigated by using elemental analysis, thermogravimetric analysis, atomic force microscopy and dynamic swelling experiments. The thermic behavior of the membranes depends on the nature of interactions and swelling degree is highly dependent on pH and composition. The properties of these membranes suggest potential applications in the field of biodegradable materials or as supports for drugs in view of their controlled release. 相似文献
143.
Renate Drozdzak Nele Ledoux Bart Allaert Ileana Dragutan Valerian Dragutan Francis Verpoort 《Central European Journal of Chemistry》2005,3(3):404-416
A two step procedure for the synthesis of a novel family of homogeneous and immobilized Ru-complexes containing Schiff bases
as O,N-bidentate ligands is described. The new Ru-complexes have been structurally characterized by IR, Raman,1H-,13C-NMR spectroscopy. The Schiff bases were associated with a diversity of inorganic and organic ligands such as chloride, phosphane,
arenes, various carbenes (alkylidene, vinylidene, indenylidene and allenylidene as well as N-heterocyclic carbenes) and cyclodienes.
By choosing a selective range of substituents for the Schiff base, useful physical and chemical properties of the prepared
Rucomplexes can be induced. This synthetic approach is promising in creating a valuable and diverse selection of Ru-complexes,
valuable for future applications. 相似文献
144.
The selective catalytic reduction (SCR) of NO by propane in excess oxygen-containing gas mixture was studied on Co/Al2O3 catalyst. The oxygen concentration is very important for the reaction. The NO conversion to N2 without oxygen is 3% at 800 K and when the O2 concentration is raised up to 8% the NO conversion reaches its maximum value of 60% at 800 K. Characterization results by
TPR and UV-Vis spectroscopy show that in the catalyst, species strongly interacting with tetrahedral and octahedral Co2+ ions in the support are present.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
145.
Stefania Ordanini Giuliano Zanchetta Vanessa Porkolab Christine Ebel Franck Fieschi Ileana Guzzetti Donatella Potenza Alessandro Palmioli Črtomir Podlipnik Daniela Meroni Anna Bernardi 《Macromolecular bioscience》2016,16(6):896-905
Glycodendrimers based on aromatic cores have an amphiphilic character and have been reported to generate supramolecuar assemblies in water. A new group of glycodendrimers with an aromatic rod‐like core were recently described as potent antagonists of DC‐SIGN‐mediated viral infections. A full characterization of the aggregation properties of these materials is presented here. The results show that these compounds exist mostly as monomers in water solution, in dynamic equilibrium with small aggregates (dimers or trimers). Larger aggregates observed by dynamic light scattering and transmission Electron Microscopy for some of the dendrimers are found to be portions of materials not fully solubilized and can be removed either by optimizing the dissolution protocol or by centrifugation of the samples.
146.
The first phase of TreeMaker, a well-known method for origami design, decomposes a planar polygon (the “paper”) into regions. If some region is not convex, TreeMaker indicates it with an error message and stops. Otherwise, a second phases is invoked which computes a crease pattern called a “universal molecule”. In this paper we introduce and study geodesic universal molecules, which also work with non-convex polygons and thus extend the applicability of the TreeMaker method. We characterize the family of disk-like surfaces, crease patterns and folded states produced by our generalized algorithm. They include non-convex polygons drawn on the surface of an intrinsically flat piecewise-linear surface which have self-overlap when laid open flat, as well as surfaces with negative curvature at a boundary vertex. 相似文献
147.
Pătraşcu Elena Badea Mihaela Čelan Korošin Nataša Cerc Korošec Romana Ruţă Lavinia L. Farcaşanu Ileana C. Grecu Maria Nicoleta Guillaumet Gérald Olar Rodica 《Journal of Thermal Analysis and Calorimetry》2021,143(1):173-184
Journal of Thermal Analysis and Calorimetry - A novel series of Cu(II) complexes with formula M(HLn)(ClO4)2·mH2O [HLn: 13-membered pentaazamacrocyclic ligand resulted from condensation of... 相似文献
148.
Gruia MI Oprea E Gruia I Negoita V Farcasanu IC 《Molecules (Basel, Switzerland)》2008,13(5):1195-1206
Lonicera caerulea is a species of bush native to the Kamchatka Peninsula (Russian Far East) whose berries have been extensively studied due to their potential high antioxidant activity. The aim of our work was to investigate the in vivo effects of the antioxidant action of Lonicera caerulea berry extracts on the dynamics of experimentally-induced tumors. Our data showed that aqueous Lonicera caerulaea extracts reduced the tumor volume when administered continuously during the tumor growth and development stages, but augmented the tumor growth when the administration of extracts started three weeks before tumor grafting. Prolonged administration of Lonicera caerulaea berry extracts induced the antioxidant defense mechanism in the tumor tissues, while surprisingly amplifying the peripheral oxidative stress. 相似文献
149.
150.
Ileana I. Rodríguez Abimael D. Rodríguez Charles L. Barnes 《Molecules (Basel, Switzerland)》2022,27(22)
Two novel dissymmetric diterpenoids, biselisabethoxanes A and B (1 and 2), were isolated from the hexane extracts of the gorgonian coral Pseudopterogorgia elisabethae. Biselisabethoxane A (1) represents the first example of a marine-derived C40 dimer made of two distinct diterpene fragments, whereas biselisabethoxane B (2) is a fused heterodimer stemming from coupling of two amphilectane-based fragments. The structures of 1 and 2 were elucidated based on 1D and 2D NMR spectral data analysis. The molecular structure of 1 was subsequently confirmed by X-ray crystallographic analysis. When evaluated for their inhibitory effects in a series of well-established biological activity assays the isolated compounds were shown to moderately inhibit the growth of Mycobacterium tuberculosis. 相似文献