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661.
662.
663.
Free vibration of thick rectangular plates is investigated by using the “method of initial functions” proposed by Vlasov. The governing equations are derived from the three-dimensional elastodynamic equations. They are obtained in the form of series and theories of any desired order can be constructed by deleting higher terms in the infinite order differential equations. The numerical results are compared with those of classical, Mindlin, and Lee and Reismann solutions. 相似文献
664.
G.P. Raja Sekhar 《Applicable analysis》2013,92(6):833-848
We have used effective medium model for beds of circular cylindrical porous fibres in order to estimate the overall bed permeability (OBP). It is assumed that a representative circular porous cylindrical fibre is inside a fluid envelope beyond which effective medium is used. Both inside the cylindrical fibre and in the effective medium, Brinkman equation is used, however of different permeabilities and in the fluid envelope Stokes equation is used. The OBP corresponding to the porous fibres is estimated when the flow direction is perpendicular to the axis of the cylindrical fibres as well as parallel to the fibres. This in turn is used to estimate the OBP corresponding to a collection of porous cylindrical fibres that are randomly oriented. We have compared the results with some existing literature. 相似文献
665.
Abu-Youssef MA Dey R Gohar Y Massoud AA Ohrström L Langer V 《Inorganic chemistry》2007,46(15):5893-5903
The synthesis and low-temperature X-ray crystal structures of five new silver complexes, [Ag(2)-mu-O,O'(2-aminonicotinium)(2)(NO(3))(2)](n) (7), [Ag(isonicotinamide)(2)-mu-O,O'(NO(3))](2) (8), [Ag(ethyl nicotinate)(2)](NO(3)) (9), [Ag(ethyl isonicotinate)(2)(NO(3))] (10), and [Ag(methyl isonicotinate)(2)(H(2)O)](NO(3)) (11), are presented and fully characterized by spectral and elemental analysis. The antimicrobial activities of these complexes were screened using 12 different clinical isolates belonging to four pathogenic bacteria, S. aureus, S. pyogenes, P. mirabilis, and Ps. Aeruginosa, all obtained from diabetic foot ulcers. These tested bacteria were resistant for at least 10 antibiotics commonly used for treatment of diabetic foot ulcers. Compounds 7 and 8 had considerable activity against Ps. Aeruginosa (MIC values 2-8 microg/mL), compound 9 against S. aureus (MIC 4-16 microg/mL) and S. pyogenes (MIC 2-4 microg/mL), and also 9 and 11 against P. mirabilis (MIC 1-16 microg/mL). All complexes were non-toxic for daphnia at concentrations above 512 microg/mL overnight. 相似文献
666.
Angamuthu R Kooijman H Lutz M Spek AL Bouwman E 《Dalton transactions (Cambridge, England : 2003)》2007,(41):4641-4643
The hexanuclear [Ni(6)L(12)] (2) wheel-type cluster adopts an unusual structural motif whereby four NiS(4) square-planar and two NiS(5) square-pyramidal units are conjoined by edge sharing; the NiS(5) units resemble the Ni centre of the inactive state in the [NiFe] hydrogenase. 相似文献
667.
Zhang Y Sheets MR Raja EK Boblak KN Klumpp DA 《Journal of the American Chemical Society》2011,133(22):8467-8469
The superacid-promoted reactions of vinyl-substituted N-heterocycles have been studied. Diprotonated pyrimidines, quinoxalines, and quinazolines exhibit an unusual regioelectronic effect that controls the type of addition reaction observed. Depending on the ring position of the vinyl substituent, either conjugate addition or Markovnikov addition occurs. The mode of addition has been shown to correlate well to NBO calculated charges. 相似文献
668.
Zhang X Richter LJ DeLongchamp DM Kline RJ Hammond MR McCulloch I Heeney M Ashraf RS Smith JN Anthopoulos TD Schroeder B Geerts YH Fischer DA Toney MF 《Journal of the American Chemical Society》2011,133(38):15073-15084
We describe a series of highly soluble diketo pyrrolo-pyrrole (DPP)-bithiophene copolymers exhibiting field effect hole mobilities up to 0.74 cm(2) V(-1) s(-1), with a common synthetic motif of bulky 2-octyldodecyl side groups on the conjugated backbone. Spectroscopy, diffraction, and microscopy measurements reveal a transition in molecular packing behavior from a preferentially edge-on orientation of the conjugated plane to a preferentially face-on orientation as the attachment density of the side chains increases. Thermal annealing generally reduces both the face-on population and the misoriented edge-on domains. The highest hole mobilities of this series were obtained from edge-on molecular packing and in-plane liquid-crystalline texture, but films with a bimodal orientation distribution and no discernible in-plane texture exhibited surprisingly comparable mobilities. The high hole mobility may therefore arise from the molecular packing feature common to the entire polymer series: backbones that are strictly oriented parallel to the substrate plane and coplanar with other backbones in the same layer. 相似文献
669.
Lazarus Godson Asirvatham Balakrishnan Raja Dhasan Mohan Lal Somchai Wongwises 《Particuology》2011,9(6):626-631
To investigate the convective heat transfer of nanofluids, experiments were performed using silver–water nanofluids under laminar, transition and turbulent flow regimes in a horizontal 4.3 mm inner-diameter tube-in-tube counter-current heat transfer test section. The volume concentration of the nanoparticles varied from 0.3% to 0.9% in steps of 0.3%, and the effects of thermo-physical properties, inlet temperature, volume concentration, and mass flow rate on heat transfer coefficient were investigated. Experiments showed that the suspended nanoparticles remarkably increased the convective heat transfer coefficient, by as much as 28.7% and 69.3% for 0.3% and 0.9% of silver content, respectively. Based on the experimental results a correlation was developed to predict the Nusselt number of the silver–water nanofluid, with ±10% agreement between experiments and prediction. 相似文献
670.
Benzynes, generated from 2-(trimethylsilyl)phenyl triflates, have been found to react with P-Alkenyl-λ(5)-phosphazenes via a formal π-insertion into the P═N bond. A subsequent retro [2 + 2] cycloaddition/6π electrocyclization/protonation cascade explains the formation of the resulting 1,4-benzazaphosphorinium triflates. P-Alkynyl λ(5)-phosphazenes and phosphane sulfides undergo similar transformations. 相似文献