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91.
A kinetic theory is developed for rarefied polyatomic gases of spherical and rough molecules with rotational energy in the
presence of an external constant magnetic field. A method of solution of Boltzmann equation that combines features of the
methods of Chapman-Enskog and Grad is used to determine transport coefficients that depend on the external magnetic field
(Senftleben-Beenakker effect).
Received August 4, 1997 相似文献
92.
93.
Johnson MM Naidoo JM Fernandes MA Mmutlane EM van Otterlo WA de Koning CB 《The Journal of organic chemistry》2010,75(24):8701-8704
Reaction of (2,4,5-trimethoxyphenyl)(2-hydroxyphenyl)methanone with ceric ammonium nitrate furnished the xanthone, 2,3-dimethoxy-9H-xanthen-9-one. Under the same conditions the related (1,4-dimethoxynaphthalen-2-yl)(2-hydroxyphenyl)methanone resulted in the formation of 12a-methoxy-5H-benzo[c]xanthenes 5,7(12aH)-dione. Other examples of this novel transformation are also outlined. 相似文献
94.
Dolgaleva K Malacarne A Tannouri P Fernandes LA Grenier JR Aitchison JS Azaña J Morandotti R Herman PR Marques PV 《Optics letters》2011,36(22):4416-4418
We experimentally demonstrate the first integrated temporal Fourier transformer based on a linearly chirped Bragg grating waveguide written in silica glass with a femtosecond laser. The operation is based on mapping the energy spectrum of the input optical signal to the output temporal waveform by making use of first-order chromatic dispersion. The device operates in reflection, has a bandwidth of 10 nm, and can be used for incident temporal waveforms as long as 20 ps. Experimental results, obtained through both temporal oscilloscope traces and Fourier transform spectral interferometry, display a successful Fourier transformation of in-phase and out-of-phase pairs of input optical pulses, and demonstrate the correct functionality of the device for both amplitude and phase of the temporal output. 相似文献
95.
Uniqueness of complete spacelike hypersurfaces via their higher order mean curvatures in a conformally stationary spacetime 下载免费PDF全文
Henrique Fernandes de Lima Marco Antonio Lázaro Velásquez 《Mathematische Nachrichten》2014,287(11-12):1223-1240
We study complete noncompact spacelike hypersurfaces immersed into conformally stationary spacetimes, that is, Lorentzian manifolds endowed with a timelike conformal vector field V. In this setting, by using as main analytical tool a suitable maximum principle for complete noncompact Riemannian manifolds, we establish new characterizations of totally umbilical hypersurfaces in terms of their higher order mean curvatures. For instance, supposing an appropriated restriction on the norm of the tangential component of the vector field V, we are able to show that such hypersurfaces must be totally umbilical provided that either some of their higher order mean curvatures are linearly related or one of them is constant. Applications to the so‐called generalized Robertson‐Walker spacetimes are given. In particular, we extend to the Lorentzian context a classical result due to Jellett 29 . 相似文献
96.
Luís M. Fernandes Joaquim J. Júdice Hanif D. Sherali Masao Fukushima 《Journal of Global Optimization》2014,59(2-3):307-326
In this paper, a parametric algorithm is introduced for computing all eigenvalues for two Eigenvalue Complementarity Problems discussed in the literature. The algorithm searches a finite number of nested intervals \([\bar{l}, \bar{u}]\) in such a way that, in each iteration, either an eigenvalue is computed in \([\bar{l}, \bar{u}]\) or a certificate of nonexistence of an eigenvalue in \([\bar{l}, \bar{u}]\) is provided. A hybrid method that combines an enumerative method [1] and a semi-smooth algorithm [2] is discussed for dealing with the Eigenvalue Complementarity Problem over an interval \([\bar{l}, \bar{u}]\) . Computational experience is presented to illustrate the efficacy and efficiency of the proposed techniques. 相似文献
97.
Fernandes SA Nachtigall FF Lazzarotto M Fujiwara FY Marsaioli AJ 《Magnetic resonance in chemistry : MRC》2005,43(5):398-404
'Non-covalent synthesis' of novel chiral hosts (calix[6]arene-chiral amine complexes) and its application to enantiomeric discrimination was investigated by (1)H NMR spectroscopy. The topology of a ternary complex was proposed for the calix[6]arene-amine-sulfoxide to rationalize the chiral recognition. 相似文献
98.
Margarida M. Antunes Andreia F. Silva Carolina D. Bernardino Auguste Fernandes Filipa Ribeiro Anabela A. Valente 《Molecules (Basel, Switzerland)》2021,26(23)
Heterogeneous catalysis, which has served well the petrochemical industry, may valuably contribute towards a bio-based economy by sustainably enabling selective reactions to renewable chemicals. Carbohydrate-containing matter may be obtained from various widespread sources and selectively converted to furanic platform chemicals: furfural (Fur) and 5-(hydroxymethyl)furfural (Hmf). Valuable bioproducts may be obtained from these aldehydes via catalytic transfer hydrogenation (CTH) using alcohols as H-donors under relatively moderate reaction conditions. Hafnium-containing TUD-1 type catalysts were the first of ordered mesoporous silicates explored for the conversion of Fur and Hmf via CTH/alcohol strategies. The materials promoted CTH and acid reactions leading to the furanic ethers. The bioproducts spectrum was broader for the reaction of Fur than of Hmf. A Fur reaction mechanism based on literature data was discussed and supported by kinetic modelling. The influence of the Hf loading and reaction conditions (catalyst load, type of alcohol H-donor, temperature, initial substrate concentration) on the reaction kinetics was studied. The reaction conditions were optimized to maximize the yields of 2-(alkoxymethyl)furan ethers formed from Fur; up to 63% yield was reached at 88% Fur conversion, 4 h/150 °C, using Hf-TUD-1(75), which was a stable catalyst. The Hf-TUD-1(x) catalysts promoted the selective conversion of Hmf to bis(2-alkoxymethyl)furan; e.g., 96% selectivity at 98% Hmf conversion, 3 h/170 °C for Hf-TUD-1(50). 相似文献
99.
de Oliveira CS Falcão-Silva Vdos S Siqueira JP Harding DP Lira BF Lorenzo JG Barbosa-Filho JM de Athayde-Filho PF 《Molecules (Basel, Switzerland)》2011,16(3):2023-2031
Two salts of the mesoionic compounds 1,4-diphenyl-5-(5-nitro-2-furanyl)-1,3,4-thiadiazolium-2-thiol chloride (MC-1) and 4-phenyl-5-(5-nitro-2-furanyl)-1,3,4-thiadiazolium-2-phenylamine chloride (MC-2) were synthesized utilizing 1,4-diphenyl-thiosemicarbazide and 5-nitro-2-furoyl chloride as starting materials. Their structures were characterized by IR, 1H-NMR, 13C-NMR and elemental analysis. These compounds were analyzed for their influence on the effectiveness of norfloxacin, tetracycline, and erythromycin (standard antibiotics) against resistant strains of Staphylococcus aureus. MC-1 and MC-2, at sub-inhibitory concentrations of 16 μg/mL, favourably modulated the antibiotic activity of tetracycline by 16- and 32-fold, respectively (MIC), and that of erythromycin by 4-fold. 相似文献
100.
Liu ZQ McCoy BK Wang ST Pindak R Caliebe W Barois P Fernandes P Nguyen HT Hsu CS Wang S Huang CC 《Physical review letters》2007,99(7):077802
Employing resonant x-ray diffraction, we observed unique pitch evolutions in the smectic-C*(alpha) phase in mixtures of two antiferroelectric liquid crystals. Our results show that the pitch in this phase continuously evolves across 4 layers, contradicting a theoretical model that predicts that the smectic-C*(FI2) phase intervenes in the smectic-C*(alpha) phase. The phase sequences we found can be explained by another model that includes one type of long-range interaction among smectic layers. 相似文献