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21.
A. Grubisic X. Li S. T. Stokes J. Cordes G. F. Gantefoer K. H. Bowen B. Kiran P. Jena R. Burgert H. Schnoeckel 《ChemInform》2007,38(31):no-no
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. 相似文献
22.
We introduce the concept of a pentagonal geometry as a generalization of the pentagon and the Desargues configuration, in the same vein that the generalized polygons share the fundamental properties of ordinary polygons. In short, a pentagonal geometry is a regular partial linear space in which for all points x, the points not collinear with the point x, form a line. We compute bounds on their parameters, give some constructions, obtain some nonexistence results for seemingly feasible parameters and suggest a cryptographic application related to identifying codes of partial linear spaces. 相似文献
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Density,viscosity, conductance,and transference number of concentrated aqueous magnesium chloride at 25°C 总被引:1,自引:0,他引:1
The density, viscosity, conductance, and transference number of aqueous magnesium chloride at 298.15°K are reported for the concentration range 0 to 5.7m. The transference numbers were determined using the emf method. It was found that the viscosity, conductance, and transference number of aqueous magnesium chloride are similar to those for aqueous nickel chloride. It was therefore tentatively concluded that incomplete dissociation and complex formation was unlikely to be of importance in nickel chloride solutions. 相似文献
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26.
Stokes JR Macakova L Chojnicka-Paszun A de Kruif CG de Jongh HH 《Langmuir : the ACS journal of surfaces and colloids》2011,27(7):3474-3484
Aqueous lubrication is currently at the forefront of tribological research due to the desire to learn and potentially mimic how nature lubricates biotribological contacts. We focus here on understanding the lubrication properties of naturally occurring polysaccharides in aqueous solution using a combination of tribology, adsorption, and rheology. The polysaccharides include pectin, xanthan gum, gellan, and locus bean gum that are all widely used in food and nonfood applications. They form rheologically complex fluids in aqueous solution that are both shear thinning and elastic, and their normal stress differences at high shear rates are found to be characteristic of semiflexible/rigid molecules. Lubrication is studied using a ball-on-disk tribometer with hydrophobic elastomer surfaces, mimicking biotribological contacts, and the friction coefficient is measured as a function of speed across the boundary, mixed, and hydrodynamic lubrication regimes. The hydrodynamic regime, where the friction coefficient increases with increasing lubricant entrainment speed, is found to depend on the viscosity of the polysaccharide solutions at shear rates of around 10(4) s(-1). The boundary regime, which occurs at the lowest entrainment speeds, depends on the adsorption of polymer to the substrate. In this regime, the friction coefficient for a rough substrate (400 nm rms roughness) is dependent on the dry mass of polymer adsorbed to the surface (obtained from surface plasmon resonance), while for a smooth substrate (10 nm rms roughness) the friction coefficient is strongly dependent on the hydrated wet mass of adsorbed polymer (obtained from quartz crystal microbalance, QCM-D). The mixed regime is dependent on both the adsorbed film properties and lubricant's viscosity at high shear rates. In addition, the entrainment speed where the friction coefficient is a minimum, which corresponds to the transition between the hydrodynamic and mixed regime, correlates linearly with the ratio of the wet mass and viscosity at ~10(4) s(-1) for the smooth surface. These findings are independent of the different polysaccharides used in the study and their different viscoelastic flow properties. 相似文献
27.
Makongo JP Misra DK Zhou X Pant A Shabetai MR Su X Uher C Stokes KL Poudeu PF 《Journal of the American Chemical Society》2011,133(46):18843-18852
Large reductions in the thermal conductivity of thermoelectrics using nanostructures have been widely demonstrated. Some enhancements in the thermopower through nanostructuring have also been reported. However, these improvements are generally offset by large drops in the electrical conductivity due to a drastic reduction in the mobility. Here, we show that large enhancements in the thermopower and electrical conductivity of half-Heusler (HH) phases can be achieved simultaneously at high temperatures through coherent insertion of nanometer scale full-Heusler (FH) inclusions within the matrix. The enhancements in the thermopower of the HH/FH nanocomposites arise from drastic reductions in the "effective" carrier concentration around 300 K. Surprisingly, the mobility increases drastically, which compensates for the decrease in the carrier concentration and minimizes the drop in the electrical conductivity. Interestingly, the carrier concentration in HH/FH nanocomposites increases rapidly with temperature, matching that of the HH matrix at high temperatures, whereas the temperature dependence of the mobility significantly deviates from the typical T(-α) law and slowly decreases (linearly) with rising temperature. This remarkable interplay between the temperature dependence of the carrier concentration and mobility in the nanocomposites results in large increases in the power factor at 775 K. In addition, the embedded FH nanostructures also induce moderate reductions in the thermal conductivity leading to drastic increases in the ZT of HH(1 - x)/FH(x) nanocomposites at 775 K. By combining transmission electron microscopy and charge transport data, we propose a possible charge carrier scattering mechanism at the HH/FH interfaces leading to the observed anomalous electronic transport in the synthesized HH(1 - x)/FH(x) nanocomposites. 相似文献
28.
Julien P.A. Makongo Dinesh K. Misra James R. Salvador Nathan J. Takas Guoyu Wang Michael R. Shabetai Aditya Pant Pravin Paudel Ctirad Uher Kevin L. Stokes Pierre F.P. Poudeu 《Journal of solid state chemistry》2011,184(11):2948-2960
Bulk Zr0.25Hf075NiSn half-Heusler (HH) nanocomposites containing various mole fractions of full-Heusler (FH) inclusions were prepared by solid state reaction of pre-synthesized HH alloy with elemental Ni at 1073 K. The microstructures of spark plasma sintered specimens of the HH/FH nanocomposites were investigated using transmission electron microscopy and their thermoelectric properties were measured from 300 K to 775 K. The formation of coherent FH inclusions into the HH matrix arises from solid-state Ni diffusion into vacant sites of the HH structure. HH(1–y)/FH(y) composites with mole fraction of FH inclusions below the percolation threshold, y∼0.2, show increased electrical conductivity, reduced Seebeck coefficient and increased total thermal conductivity arising from gradual increase in the carrier concentration for composites. A drastic reduction (∼55%) in κl was observed for the composite with y=0.6 and is attributed to enhanced phonon scattering due to mass fluctuations between FH and HH, and high density of HH/FH interfaces. 相似文献
29.
Acoustic resonances are generated by air moving past a plate with a semi-circular leading edge located in a duct. The sound stimulates the small separation bubble near the leading edge to shed vortices into the boundary layer at the sound frequency. The acoustic energy required to sustain the resonances is generated as these vortices pass the trailing edge of the plate. 相似文献
30.
Adam A. Stokes David J. Clarke Stefan Weidt Pat Langridge-Smith C. Logan Mackay 《International journal of mass spectrometry》2010,289(1):54-57
We report high resolution spectra for the medium molecular weight proteins myoglobin and cytochrome-c obtained using a custom desorption electrospray ionisation (DESI) source coupled to a Bruker Daltonics 12 T Apex Qe Fourier transform ion cyclotron resonance mass spectrometer (FTICR-MS). The DESI source was designed for accurate alignment and reproduction of critical geometric variables. A two axis motorised stage was included to enable automated rastering of the sample under the DESI plume. Spectra for the intact proteins have been obtained under single-acquisition conditions and a top-down analysis of cytochrome-c was performed using both collision induced dissociation (CID) and electron capture dissociation (ECD) of the isolated [M+15H]15+ charge state. The sequence coverage is comparable to that obtained using electrospray ionisation, demonstrating the utility of top-down protein analysis by DESI FTICR-MS. 相似文献