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51.
F. Guillén–González M. A. Rodríguez–Bellido M. A. Rojas–Medar 《Mathematische Nachrichten》2009,282(6):846-867
In [3], L. Berselli showed that the regularity criterion ? u ∈ (0, T; L q (Ω)), for some q ∈ (3/2, + ∞], implies regularity for the weak solutions of the Navier–Stokes equations, being u the velocity field. In this work, we prove that such hypothesis on the velocity gradient is also sufficient to obtain regularity for a nematic Liquid Crystal model (a coupled system of velocity u and orientation crystals vector d ) when periodic boundary conditions for d are considered (without regularity hypothesis on d ). For Neumann and Dirichlet cases, the same result holds only for q ∈ [2, 3], whereas for q ∈ (3/2, 2) ∪ (3, + ∞] additional regularity hypothesis for d (either on ? d or Δ d ) must be imposed. On the other hand, when the Serrin's criterion u ∈ (0, T; L p (Ω)) with some p ∈ (3, + ∞] ([16]) for u is imposed, we can obtain regularity of the system only in the problem of periodic boundary conditions for d . When Neumann and Dirichlet cases for d are considered, additional regularity for d must be imposed for each p ∈ (3, + ∞] (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
52.
53.
Fernández-Martínez R Caballero R Guillén C Gutiérrez MT Rucandio MI 《Analytical and bioanalytical chemistry》2005,382(2):466-470
CuIn1–xGaxSe2 [CIGS; x=Ga/(In+Ga)] thin films are among of the best candidates as absorber materials for solar cell applications. The material quality and main properties of the polycrystalline absorber layer are critically influenced by deviations in the stoichiometry, particularly in the Cu/(In+Ga) atomic ratio. In this work a simple, sensitive and accurate method has been developed for the quantitative determination of these thin films by inductively coupled plasma optical emission spectrometry (ICP-OES). The proposed method involves an acid digestion of the samples to achieve the complete solubilization of CIGS, followed by the analytical determination by ICP-OES. A digestion procedure with 50% HNO3 alone or in the presence of 10% HCl was performed to dissolve those thin films deposited on glass or Mo-coated glass substrates, respectively. Two analytical lines were selected for each element (Cu 324.754 and 327.396 nm, Ga 294.364 and 417.206 nm, In 303.936 and 325.609 nm, Se 196.090 and 203.985 nm, and Mo 202.030 and 379.825 nm) and a study of spectral interferences was performed which showed them to be suitable, since they offered a high sensitivity and no significant inter-element interferences were detected. Detection limits for all elements at the selected lines were found to be appropriate for this kind of application, and the relative standard deviations were lower than 1.5% for all elements with the exception of Se (about 5%). The Cu/(In+Ga) atomic ratios obtained from the application of this method to CIGS thin films were consistent with the study of the structural and morphological properties by X-ray diffraction (XRD) and scanning electron microscopy (SEM). 相似文献
54.
Dominico Cupertino Robin Keyte Alexandra M.Z. Slawin J.Derek Woollins David J. Williams 《Polyhedron》1996,15(24):4441-4445
Reaction of PtCl2(cod) with Pr2i P(S)NHP(S)Pr2i gives [M*N(Pr2i PS)2*2] M = Pt1, Pd 2). Repeated crystallization of the palladium complex from CH2Cl2 resulted in the protonation of one ligand to give [Pd*HN(Pr2i PS)2**N(Pr2i PS)2*]Cl. The X-ray structures of 1 and 2 reveal a dramatic change from flattened chair to pseudo-boat conformation for the MS2P2N rings. Protonation of the ring does not appear to have major effects on ring conformation. VT 31P NMR studies on 1 suggest the presence of two conformers at low temperature. 相似文献
55.
J. A. Silva-Chong O. Guillén-Villafuerte J. L. Rodríguez E. Pastor 《Journal of Solid State Electrochemistry》2008,12(5):517-522
The formation of acetaldehyde adsorbates on Pt and Pd has been studied applying cyclic voltammetry and differential electrochemical
mass spectrometry (DEMS). The adspecies were isolated on the metal surface at selected adsorption potentials (E
ad) applying a flow cell procedure under potential control, and the anodic stripping were performed for each E
ad. For Pt, two different contributions were established during oxidation: one at E < 0.80 V and the second in the range 0.80–1.50 V in the Pt oxide region. For Pd, the voltammetric profile resembles that
for the oxidation of adsorbed CO. DEMS experiments have shown that CO2 was the sole electro-oxidation product in both cases. The oxidation of each C atom in acetaldehyde adsorbates has been distinguished
using the isotopic-labelled aldehyde in DEMS experiments at selected E
ad. It was observed that, on Pt, acetaldehyde molecules loose part of the CH3 groups during adsorption at E
ad < 0.40 V, whereas the CHO groups are easily oxidized at E
ad > 0.40 V. Therefore, both C1 and C2 species are present on the surface, and their yields depend on E
ad. On the contrary, on Pd, most of the CH3 groups are lost during adsorption at all E
ad, and the main adsorbed species seems to be COad.
Dedicated to Prof. Dr. Teresa Iwasita on the occasion of her 65th birthday in recognition of her numerous contributions to
interfacial electrochemistry. 相似文献
56.
Smotherman M Guillén-Servent A 《The Journal of the Acoustical Society of America》2008,123(6):4331-4339
Doppler-shift compensation behavior (DSC) is a highly specialized vocal response displayed by bats that emit pulses with a prominent constant frequency (CF) component and adjust the frequency of their CF component to compensate for flight-speed induced Doppler shifts in the frequency of the returning echoes. DSC has only been observed in one member of the Neotropical Mormoopidae, a family of bats that use pulses with prominent CF components, leading researchers to suspect that DSC is a uniquely derived trait in the single species Pteronotus parnellii. Yet recent phylogenetic data indicate that the lineage of P. parnellii originates from the most basal node in the evolutionary history of the genus Pteronotus. DSC behavior was investigated in another member of this family, Pteronotus personatus, because molecular data indicated that this species stems from the second most basal node in Pteronotus. DSC was tested for by swinging the bats on a pendulum. P. personatus performed DSC as well as P. parnellii under identical conditions. Two other closely related mormoopids, Pteronotus davyi and Mormoops megalophylla, were also tested and neither shifted the peak frequency of their pulses. These results shed light on the evolutionary history of DSC among the mormoopids. 相似文献
57.
Jacques Bair Piotr Błaszczyk Elías Fuentes Guillén Peter Heinig Vladimir Kanovei Mikhail G. Katz 《BSHM Bulletin: Journal of the British Society for the History of Mathematics》2020,35(3):207-224
In a paper published in 1970, Grattan-Guinness argued that Cauchy, in his 1821 Cours d'Analyse, may have plagiarized Bolzano's Rein analytischer Beweis (RB), first published in 1817. That paper was subsequently discredited in several works, but some of its assumptions still prevail today. In particular, it is usually considered that Cauchy did not develop his notion of the continuity of a function before Bolzano developed his in RB and that both notions are essentially the same. We argue that both assumptions are incorrect, and that it is implausible that Cauchy's initial insight into that notion, which eventually evolved to an approach using infinitesimals, could have been borrowed from Bolzano's work. Furthermore, we account for Bolzano's interest in that notion and focus on his discussion of a definition by Kästner (in Section 183 of his 1766 book), which the former seems to have misrepresented at least partially. 相似文献
58.
A method has been developed for the simultaneous determination of resveratrol in all its forms (free isomers and glycosylates) in wines by high-performance liquid chromatography with diode array and mass spectrometric detection. Prior to injection into the column, preconcentration of the sample by automated solid-phase extraction is carried out. In the detection by UV absorption, quantitation was carried out at 280 and 305 nm, and in detection by mass spectrometry, quantitation was performed in the selected ion monitoring mode at m/z 228 and at m/z 238. A comparative study between both detection systems was carried out. 相似文献
59.
Guillén J de Almeida RF Prieto M Villalaín J 《The journal of physical chemistry. B》2008,112(23):6997-7007
The SARS coronavirus (SARS-CoV) envelope spike (S) glycoprotein, a Class I viral fusion protein, is responsible for the fusion between the membranes of the virus and the target cell. In the present work, we report a study of the binding and interaction with model membranes of a peptide pertaining to the putative fusion domain of SARS-CoV, SARS FP, as well as the structural changes that take place in both the phospholipid and the peptide molecules upon this interaction. From fluorescence and infrared spectroscopies, the peptide ability to induce membrane leakage, aggregation and fusion, as well as its affinity toward specific phospholipids, was assessed. We demonstrate that SARS FP strongly partitions into phospholipid membranes, more specifically with those containing negatively charged phospholipids, increasing the water penetration depth and displaying membrane-activity modulated by the lipid composition of the membrane. Interestingly, peptide organization is different depending if SARS FP is in water or bound to the membrane. These data suggest that SARS FP could be involved in the merging of the viral and target cell membranes by perturbing the membrane outer leaflet phospholipids and specifically interacting with negatively charged phospholipids located in the inner leaflet. 相似文献
60.
We introduce the spectral property (R), for bounded linear operators defined on a Banach space, which is related to Weyl type theorems. This property is also studied
in the framework of polaroid, or left polaroid, operators. 相似文献