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41.
Nicuşor Costea Daniel Alexandru Ion Cezar Lupu 《Journal of Optimization Theory and Applications》2012,155(1):79-99
The aim of this paper is to establish existence results for some variational-like inequality problems involving set-valued maps, in reflexive and nonreflexive Banach spaces. When the set K, in which we seek solutions, is compact and convex, we no dot impose any monotonicity assumptions on the set-valued map A, which appears in the formulation of the inequality problems. In the case when K is only bounded, closed, and convex, certain monotonicity assumptions are needed: We ask A to be relaxed η-α monotone for generalized variational-like inequalities and relaxed η-α quasimonotone for variational-like inequalities. We also provide sufficient conditions for the existence of solutions in the case when K is unbounded, closed, and convex. 相似文献
42.
P. Thakur J. C. Cezar N. B. Brookes R. J. Choudhary D. M. Phase K. H. Chae Ravi Kumar 《Hyperfine Interactions》2010,197(1-3):95-100
The electronic and magnetic properties of well characterized Mo1???xFexO2 (x = 0–0.5) thin films that show ferromagnetism at room temperature (RT) have been investigated by the means of near edge x-ray absorption fine structure (NEXAFS) and x-ray magnetic circular dichroism (XMCD) experiments at the O K-, Fe L-, and Mo M-edges. The NEXAFS spectra at O K- and Mo M3,2 -edges show a strong hybridization of O 2p-4d Mo orbitals, and Mo ions change their symmetry with the substitution of Fe ions into MoO2 matrix. The Fe 2p NEXAFS/XMCD spectra exhibit multiple absorption peaks and an appreciable XMCD signal that persists even at RT. These results demonstrate that Fe is in a mixed valence state of Fe2?+?–Fe3?+?, substituting at the Mo site and that the Fe2?+?/3?+? ions are ferromagnetically polarized. 相似文献
43.
Cezar A. Bizzi Joaquim A. Nóbrega Juliano S. Barin Jussiane S.S. Oliveira Lucas Schmidt Paola A. Mello Erico M.M. Flores 《Analytica chimica acta》2014
The present work evaluates the influence of vessel cooling simultaneously to microwave-assisted digestion performed in a closed system with diluted HNO3 under O2 pressure. The effect of outside air flow-rates (60–190 m3 h−1) used for cooling of digestion vessels was evaluated. An improvement in digestion efficiency caused by the reduction of HNO3 partial pressure was observed when using higher air flow-rate (190 m3 h−1), decreasing the residual carbon content for whole milk powder from 21.7 to 9.3% (lowest and highest air flow-rate, respectively). The use of high air flow-rate outside the digestion vessel resulted in a higher temperature gradient between liquid and gas phases inside the digestion vessel and improved the efficiency of sample digestion. Since a more pronounced temperature gradient was obtained, it contributed for increasing the condensation rate and thus allowed a reduction in the HNO3 partial pressure of the digestion vessel, which improved the regeneration of HNO3. An air flow-rate of 190 m3 h−1 was selected for digestion of animal fat, bovine liver, ground soybean, non fat milk powder, oregano leaves, potato starch and whole milk powder samples, and a standard reference material of apple leaves (NIST 1515), bovine liver (NIST 1577) and whole milk powder (NIST 8435) for further metals determination by inductively coupled plasma atomic emission spectroscopy (ICP-OES). Results were in agreement with certified values and no interferences caused by matrix effects during the determination step were observed. 相似文献
44.
Maia GL Falcão-Silva Vdos S Aquino PG de Araújo-Júnior JX Tavares JF da Silva MS Rodrigues LC de Siqueira-Júnior JP Barbosa-Filho JM 《Molecules (Basel, Switzerland)》2011,16(6):4828-4835
Chemical studies of Praxelis clematidea R.M. King & Robinson resulted in the isolation of six flavones: Apigenine, genkwanine, 7,4'-dimethylapigenin, trimethylapigenin, cirsimaritin and tetramethylscutellarein, which were tested for their toxicity against Staphylococcus aureus SA-1199B, a strain possessing the NorA efflux pump. Efflux pumps are integral proteins of the bacterial membrane and are recognized as one of the main causes of bacterial drug resistance, since they expel antibiotics from the cell. The inhibition of this transporter is one form of modulating bacterial resistance to antimicrobial drugs. The flavones tested did not show any significant antibacterial activity against the Staphylococcus aureus strain used, but were able to modulate bacterial drug resistance. This property might be related to the degree of lipophilicity of the flavones conferred by the methoxyl groups, since 4',5,6,7 tetramethoxyflavone the most methoxylated compound, reduced the minimal inhibitory concentration of the drug 16-fold. 相似文献
45.
Bruno FY Garcia-Barriocanal J Varela M Nemes NM Thakur P Cezar JC Brookes NB Rivera-Calzada A Garcia-Hernandez M Leon C Okamoto S Pennycook SJ Santamaria J 《Physical review letters》2011,106(14):147205
We report on the magnetic coupling of La0.7Sr0.3MnO3 layers through SrTiO3 spacers in La0.7Sr0.3MnO3/SrTiO3 epitaxial heterostructures. Combined aberration-corrected microscopy and electron-energy-loss spectroscopy evidence charge transfer to the empty conduction band of the titanate. Ti d electrons interact via superexchange with Mn, giving rise to a Ti magnetic moment as demonstrated by x-ray magnetic circular dichroism. This induced magnetic moment in the SrTiO3 controls the bulk magnetic and transport properties of the superlattices when the titanate layer thickness is below 1 nm. 相似文献
46.
Julio Cezar Paz de Mattos Luiz Frederico Rodrigues Érico Marlon de Moraes Flores Viliam Krivan 《Spectrochimica Acta Part B: Atomic Spectroscopy》2011,66(8):637-643
The trace impurities Cr, Cu, Fe, K, Mn, Sb and Zn were determined in powdered aluminum nitride by direct solid sampling graphite furnace atomic absorption spectrometry using a ZEEnit 60 atomic absorption spectrometer. This spectrometer features inverse Zeeman-effect background correction and a variable magnetic field enabling measurements in two sensitivity modes over a concentration range of three orders of magnitude. The measurement sensitivity can be adjusted to the analyte concentration in the sample. The use of chemical modifiers was not necessary. Calibration was carried out by means of calibration curves obtained with aqueous standard solutions. Accuracy was checked mainly by comparison of the results with those obtained by instrumental and radiochemical neutron activation analysis whereby, excluding the results for potassium, no significant differences were found by carrying out the t-test at the significance level 0.05. The limits of detection were between 0.05 ng g−1 (Zn) and 80 ng g−1 (Fe) and the relative standard deviations below 11 %. With the proposed method, up to ten measurement cycles can be carried out in one hour. 相似文献
47.
We obtain several rigidity results for biharmonic submanifolds in $\mathbb{S}^{n}$ with parallel normalized mean curvature vector fields. We classify biharmonic submanifolds in $\mathbb{S}^{n}$ with parallel normalized mean curvature vector fields and with at most two distinct principal curvatures. In particular, we determine all biharmonic surfaces with parallel normalized mean curvature vector fields in $\mathbb{S}^{n}$ . Then we investigate, for (not necessarily compact) proper-biharmonic submanifolds in $\mathbb{S}^{n}$ , their type in the sense of B.-Y. Chen. We prove that (i) a proper-biharmonic submanifold in $\mathbb{S}^{n}$ is of 1-type or 2-type if and only if it has constant mean curvature f=1 or f∈(0,1), respectively; and (ii) there are no proper-biharmonic 3-type submanifolds with parallel normalized mean curvature vector fields in $\mathbb{S}^{n}$ . 相似文献
48.
Diogo?E.?V.?AndradeEmail author Moisés?A.?Marcelino Neto Cezar?O.?R.?Negr?o 《Rheologica Acta》2018,57(10):673-680
The oil at high temperatures in the reservoir loses heat to the surroundings and is submitted to different shear stresses while it is produced and transported. Thermal and shear histories have great influence on the rheological characteristics of waxy oils at low temperature. Wax crystals precipitate during cooling, building up a percolated matrix that entraps the oil and consequently, forms a gel-like structure. One of the main parameters that affect the crystals’ morphology and therefore the gel strength is the cooling rate. Although the oil static cooling has been widely studied in the literature, many questions are still open. The current work analyzes the influence of the cooling rate on the gel strength and on the dynamic moduli (G′ and G″) of a waxy model oil. Microscopic images of wax crystals were obtained and a hypothesis to explain the non-monotonic response of the rheological parameters as a function of the cooling rate is proposed based on the crystals’ morphology. 相似文献
49.
Andrs Seoane Cezar Comanescu Noelia Casanova Rebeca García‐Fandio Xabier Diz Jos L. Mascareas Moiss Gulías 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(6):1714-1718
o‐Alkenyl N‐triflylanilides underwent rhodium(III)‐catalyzed oxidative annulations with alkynes to produce different types of naphthylamides in a process which involves the cleavage of two C?H bonds. Remarkably, besides formal dehydrogenative (4C+2C) cycloadducts, the reaction also produces variable amounts of isomeric naphthylamides, whose formation requires a formal migration of the alkenyl moiety from the ortho to the meta position of the anilide. The annulation reaction can be efficiently carried out in the absence of external oxidants, such as Cu(OAc)2. 相似文献
50.
Cezar Juliana Guerreiro Carvalho José Roque Mota Ferreira Kleber Queiroz 《Transition Metal Chemistry》2019,44(3):253-261
Transition Metal Chemistry - We report here the synthesis, characterization and kinetic studies of [RuL2(mac)]n+ complexes [mac?=?1,4,8,11-tetraazacyclotetradecane (cyclam) or... 相似文献