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71.
Lahorija Bistričić Goran Baranović Mirela Leskovac Emi Govorčin Bajsić 《Macromolecular Symposia》2011,305(1):126-131
Thin films of polyester-based polyurethane-silica nanocomposites with 34% hard segments and different concentrations of nano SiO2 filler (0, 0.5, 1.0 and 3 vol.%) have been prepared. The hydrogen bonding and orientational behaviour of hard and soft segments were analysed using infrared linear dichroic measurements. The number of hydrogen bonded NH and CO groups and orientation function were calculated from polarized FTIR spectra. The presence of nanosilica slightly increased the number of hydrogen bonded carbonyls. The soft segments in nanocomposite films display increased orientation in comparison to the neat polymer film. The addition of 3% nanosilica significantly reduced elongation at break. The results were compared with hydrogen bonding and orientational behaviour of thin film of polyether-based silica nanocomposites. 相似文献
72.
Ian Graham Hidetaka Hamada Gabriela Kohr Mirela Kohr 《Complex Analysis and Operator Theory》2013,7(6):1909-1927
In this paper we consider the notion of asymptotic spirallikeness in reflexive complex Banach spaces $X$ , and the connection with univalent subordination chains. Poreda initially introduced the notion of asymptotic starlikeness to characterize biholomorphic mappings on the unit polydisc in $\mathbb{C }^{n}$ which have parametric representation in the sense of Loewner theory. The authors introduced the notions of $A$ -asymptotic spirallikeness and $A$ -parametric representation on the Euclidean unit ball of $\mathbb{C }^{n}$ , where $A\in L(\mathbb{C }^{n})$ with $m(A)>0$ . They showed that these notions are equivalent whenever $k_+(A)<2m(A)$ . In this paper we prove that if $k_+(A)<2m(A)$ and $f\in S(B)$ has $A$ -parametric representation, then $f$ is also $A$ -asymptotically spirallike on the unit ball $B$ of $X$ . For the converse, we need the additional assumption that $f$ is a smooth $A$ -asymptotically spirallike mapping, except in the finite-dimensional case $X=\mathbb{C }^{n}$ with an arbitrary norm. The notion of asymptotic spirallikeness involves differential equations and may be regarded as giving a geometric characterization of certain domains in $X$ . That is one of the motivations for considering this notion in the case of reflexive complex Banach spaces. 相似文献
73.
Mirela Barbu Mircea Stefanescu Marcela Stoia Gabriela Vlase Paul Barvinschi 《Journal of Thermal Analysis and Calorimetry》2012,108(3):1059-1066
In this article, we present a new method for the obtaining of ZnCr2O4 and MgCr2O4 embedded in silica matrix. This method consists in the formation of Cr(III), Zn(II) and Cr(III), Mg(II) hydroxycarboxylate/carboxylate compounds, during the redox reaction between the nitrate ion and diol (1,3-propanediol), uniformly dispersed in the pores of hybrid gels. The thermal decomposition of these precursors leads to a mixture of corresponding metal oxides. The gels were synthesized starting from mixtures of Cr(NO3)3·9H2O, Zn(NO3)2·6H2O and Cr(NO3)3·9H2O, Mg(NO3)2·6H2O with tetraethyl orthosilicate and 1,3-propanediol for final compositions 50% ZnCr2O4/50% SiO2 and 50% MgCr2O4/50% SiO2. The obtained gels have been thermally treated at 140?°C, when the redox reaction nitrates-diol took place with formation of the precursors within the xerogels pores. The thermal decomposition of all precursors took place up to 300?°C, with formation of oxides mixtures (Cr2O3?+?x and ZnO) and (Cr2O3?+?x and MgO), respectively. At 400?°C, Cr2O3?+?x turn to Cr2O3 which reacts with ZnO forming ZnCr2O4/SiO2. Starting with 400?°C, Cr2O3 reacts with MgO to an intermediary phase MgCrO4, which decomposes with the formation of MgCr2O4/SiO2. The formation of the precursors inside the silica matrix and the evolution of the crystalline phases were studied by thermal analysis, FT-IR spectrometry, XRD, and TEM. 相似文献
74.
Dirichlet problem for a nonlinear generalized Darcy–Forchheimer–Brinkman system in Lipschitz domains
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Teodor Groşan Mirela Kohr Wolfgang L. Wendland 《Mathematical Methods in the Applied Sciences》2015,38(17):3615-3628
The purpose of this paper is to show existence of a solution of the Dirichlet problem for a nonlinear generalized Darcy–Forchheimer–Brinkman system in a bounded Lipschitz domain in , with small boundary datum in L2‐based Sobolev spaces. A useful intermediary result is the well‐posedness of the Poisson problem for a generalized Brinkman system in a bounded Lipschitz domain in , with Dirichlet boundary condition and data in L2‐based Sobolev spaces. We obtain this well‐posedness result by showing that the matrix type operator associated with the Poisson problem is an isomorphism. Then, we combine the well‐posedness result from the linear case with a fixed point theorem in order to show the existence of a solution of the Dirichlet problem for the nonlinear generalized Darcy–Forchheimer–Brinkman system. Some applications are also included. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
75.
Gregory B. Kharas Xue Tian Joanna Alegarbes Andrea T. Bartosik Mirela Hadziahmetovic Asra K. Hai 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(6):565-568
Electrophilic trisubstituted ethylene monomers, ring‐substituted 2‐cyano‐N,N‐dimethyl‐3‐phenyl‐2‐propenamides, RC6H4CH?C(CN)CON(CH3)2 (where R is 3‐benzyloxy, 4‐benzyloxy, 3‐ethoxy‐4‐methoxy, 3‐bromo‐4‐methoxy, 5‐bromo‐2‐methoxy, 2‐chloro‐6‐fluoro) were synthesized by potassium hydroxide catalyzed Knoevenagel condensation of ring‐substituted benzaldehydes and N,N‐dimethyl cyanoacetamide, and characterized by CHN elemental analysis, IR, 1H‐ and 13C‐NMR. Novel copolymers of the ethylenes and styrene were prepared at equimolar monomer feed composition by solution copolymerization in the presence of a radical initiator, ABCN at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, 1H and 13C NMR, GPC, DSC, and TGA. High Tg of the copolymers in comparison with that of polystyrene indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. The gravimetric analysis indicated that the copolymers decompose in the 300–450°C range. 相似文献
76.
Ivica Cepanec Mladen Litvi? Mirela Filipan-Litvi? Ivana Grüngold 《Tetrahedron》2007,63(48):11822-11827
Antimony(III) chloride (20 mol %) in refluxing acetonitrile efficiently catalyses the synthesis of dihydropyrimidinones (50-90% yields) by the Biginelli reaction of aromatic aldehydes, acetoacetate esters and urea. This reaction proceeds through 3-ureido-crotonates followed by cyclisation with an aromatic aldehyde to the dihydropyrimidinone. 相似文献
77.
Sedic M Kraljevic Pavelic S Cindric M Vissers JP Peronja M Josic D Cuk M Fumic K Pavelic K Baric I 《Electrophoresis》2011,32(15):1970-1975
S-Adenosylhomocysteine hydrolase (AHCY) deficiency is a rare congenital disorder in methionine metabolism clinically characterized by white matter atrophy, delayed myelination, slowly progressive myopathy, retarded psychomotor development and mildly active chronic hepatitis. In the present study, we utilized a comparative proteomics strategy based on 2-DE/MALDI-MS and LC/ESI-MS to analyze plasma proteins from three AHCY-deficient patients prior to and after receiving dietary treatment designed to alleviate disease symptoms. Obtained results revealed candidate biomarkers for the detection of myopathy specifically associated with AHCY deficiency, such as carbonic anhydrase 3, creatine kinase, and thrombospondin 4. Several proteins mediating T-cell activation and function were identified as well, including attractin and diacylglycerol kinase α. Further validation and functional analysis of identified proteins with clinical value would ensure that these biomarkers make their way into routine diagnosis and management of AHCY deficiency. 相似文献
78.
In this paper a necessary and sufficient condition is found for the existence of non-zero modes, which satisfy the Pridmore–Brown equation and the mass-spring-damper impedance boundary condition. The flowing fluid is assumed to be inviscid, non-slipping and compressible. The mean flow velocity profile in the equation is assumed to be function of y only. The condition which is found defines in fact a dispersion relation, which has to be used in the linear stability analysis of the flow also by Briggs–Bers method. As far as we know, the dispersion relation reported in the present paper is new and it is not an obvious consequence of other results already reported in the literature. The numerical illustration shows that the dispersion-relation is effective and for the considered numerical data reveals the existence of mode type initial perturbations whose amplitude increase exponentially in time showing linear instability. In the same time the numerical illustration reveals the existence of mode type initial perturbations whose amplitude decrease exponentially tending to zero for t tending to plus infinity. 相似文献
79.
Ivana Buljeta Anita Pichler Ivana Ivi Josip imunovi Mirela Kopjar 《Molecules (Basel, Switzerland)》2021,26(14)
Production and storage, the influence of packaging materials and the presence of other ingredients in fruit products can cause changes in flavor compounds or even their loss. Due to these issues, there is a need to encapsulate flavor compounds, and polysaccharides are often used as efficient carriers. In order to achieve effective encapsulation, satisfactory retention and/or controlled release of flavor compounds, it is necessary to understand the nature of the coated and coating materials. Interactions that occur between these compounds are mostly non-covalent interactions (hydrogen bonds, hydrophobic interactions and van der Waals forces); additionally, the formation of the inclusion complexes of flavor compounds and polysaccharides can also occur. This review provides insight into studies about the encapsulation of flavor compounds, as well as basic characteristics of encapsulation such as the choice of coating material, the effect of various factors on the encapsulation efficiency and an explanation of the nature of binding. 相似文献
80.
Denisa Fericean Teodor Groşan Mirela Kohr Wolfgang L. Wendland 《Mathematical Methods in the Applied Sciences》2013,36(12):1631-1648
In this paper, we describe a layer potential analysis in order to show an existence result for an interface boundary value problem of Robin‐transmission type for the Stokes and Brinkman systems on Lipschitz domains in Euclidean setting, when the given boundary data belong to some Lp or Sobolev spaces associated to such domains. Applications related to an exterior three‐dimensional Stokes flow past two concentric porous spheres with stress jump conditions on the fluid‐porous interface are also considered. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献