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排序方式: 共有124条查询结果,搜索用时 15 毫秒
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Ramanan Pitchumani Nishant Gupta GabrielM.H. Meesters Brian Scarlett 《Particle & Particle Systems Characterization》2003,20(5):323-326
Particle breakage can be characterised as attrition, chipping, fracture, abrasion and wear. All these types of breakage mechanisms are the effect of the damage caused to these particles. These mechanisms can be differentiated not just on the basis of magnitude and direction of the force but also by the damage caused to the particles. The damage is measured by change in the size distribution and the change in shape of the particles. In the current research, experiments were performed on the newly developed Repeated Impact Test. The unique feature of this test is that about hundred particles can be subjected simultaneously to a monitored number of impacts, without particle‐particle interactions at regulated velocities. The preliminary experiments were performed with single crystalline particles of different shapes and sizes. After fixed number of impacts, the images of the particles were taken. The volume and shape of the particles were determined by image analysis. It was observed that the rate of attrition was very high when the particles are irregular. The rate decreased as the particles became more spherical. 相似文献
13.
A general third-order dynamical system with polynomial right-hand sides of finite degrees in the dependent variables is analyzed to unravel the singularity structure of its solutions about a movable singular point. To that end, the system is first transformed to a second-order Briot–Bouquet system and a third auxiliary equation via a transformation, similar to one used earlier by R. A. Smith in 1973–1974 for a general second-order dynamical system. This transformation imposes some constraints on the coefficients appearing in the general third-order system. The known results for the second-order Briot–Bouquet system are used to explicitly write out Laurent or psi-series solutions of the general third-order system about a movable singularity. The convergence of the relevant series solutions in a deleted neighborhood of the singularity is ensured. The theory developed here is illustrated with the help of the May–Leonard system. 相似文献
14.
Generalized processor sharing has been proposed as a policy for distributing processing in a fair manner between different
data classes in high-speed networks. In this paper we show how recent results on the Skorokhod Problem can be used to construct
and analyze the mapping that takes the input processes into the buffer content. More precisely, we show how to represent the
map in terms of a Skorokhod Problem, and from this infer that the mapping is well defined (existence and uniqueness) and well
behaved (Lipschitz continuity). As an elementary application we present some large deviation estimates for a many data source
model.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
15.
We have measured the permeability of rhodamine-6G across Cx43 hemichannels reconstituted on a pipette tip. Cx43 hemichannels
were overexpressed in Sf9 cells, and affinity-purified. The hemichannels were reconstituted in a lipid bilayer on a pipette
tip by the tip-dip method. R6G in the pipette permeated across the channels into the bath. The permeability of R6G was quantified
by measuring R6G concentration in the bath after several hours by surface enhanced Raman spectroscopy (SERS) with 100 nm silver
colloid particles. The ratio of the permeability of dye to salt, as extracted by this combined electrical-SERS technique,
is compatible with similar ratios for other dyes across whole gap junction channels. The results for the permeability ratio
were further compared to fluorescence measurements. The novel combination of patch and SERS techniques can be extended to
quantifying the transport of biologically significant non-fluorescent molecules, such as cAMP and IP3, across 1 nm sized pores,
such as the gap junction channel. 相似文献
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Shobhit S. Chaturvedi Rajeev Ramanan Sodiq O. Waheed Jon Ainsley Martin Evison Jennifer M. Ames Christopher J. Schofield Tatyana G. Karabencheva-Christova Christo Z. Christov 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(21):5422-5426
The human KDM7 subfamily histone H3 Nϵ-methyl lysine demethylases PHF8 (KDM7B) and KIAA1718 (KDM7A) have different substrate selectivities and are linked to genetic diseases and cancer. We describe experimentally based computational studies revealing that flexibility of the region linking the PHD finger and JmjC domains in PHF8 and KIAA1718 regulates interdomain interactions, the nature of correlated motions, and ultimately H3 binding and demethylation site selectivity. F279S an X-linked mental retardation mutation in PHF8 is involved in correlated motions with the iron ligands and second sphere residues. The calculations reveal key roles of a flexible protein environment in productive formation of enzyme-substrate complexes and suggest targeting the flexible KDM7 linker region is of interest from a medicinal chemistry perspective. 相似文献
19.
Kumar S Davis TM Ramanan H Penn RL Tsapatsis M 《The journal of physical chemistry. B》2007,111(13):3398-3403
Precursor silica nanoparticles can evolve to silicalite-1 crystals under hydrothermal conditions in the presence of tetrapropylammonium (TPA) cations. It has been proposed that in relatively dilute sols of silica, TPA, water, and ethanol, silicalite-1 growth is preceded by precursor nanoparticle evolution and then occurs by oriented aggregation. Here, we present a study of silicalite-1 crystallization in more concentrated mixtures and propose that growth follows a path similar to that taken in the dilute system. Small-angle X-ray scattering (SAXS), cryogenic transmission electron microscopy (cryo-TEM), and high-resolution transmission electron microscopy (HRTEM) were used to measure nanoparticle size and to monitor zeolite nucleation and early-stage crystal development. The precursor silica nanoparticles, present in the clear sols prior to crystal formation, were characterized using two SAXS instruments, and the influence of interparticle interactions is discussed. In addition, SAXS was used to detect the onset of secondary particle formation, and HRTEM was used to characterize their structure and morphology. Cryo-TEM allowed for in situ visual observation of the nanoparticle population. Combined results are consistent with growth by aggregation of silica nanoparticles and of the larger secondary crystallites. Finally, a unique intergrowth structure that was formed during the more advanced growth stages is reported, lending additional support for the proposal of aggregative growth. 相似文献
20.
New Scheelite-related solid solutions of the compositions Nax/2Bi1−x/2MoxV1−xO4 (0≤x≤1) and Bi1−x/3 MoxV1−xO4(0≤x≤0.2) have been synthesised by the substitution of Na and Mo at the A and B sites respectively of the ABO4 type ferroelastic BiVO4. The phases were characterised using chemical analysis, powder X-ray diffraction, scanning electron microscopy, EDAX, and Raman spectroscopy. While almost a continuous solid solution is obtained for the series Nax/2Bi1−x/2MoxV1−xO4, the absence of Na at the A-site results only in a narrow stability region for the other series, Bi1−x/3 MoxV1−xO4 where 0≤x≤0.2. Raman spectra of selected samples at room temperature also suggest that vanadium and molybdenum atoms are disordered at the tetrahedral sites. 相似文献