scholarly journals Tribo-electric charging of dielectric solids of identical composition

2018 ◽  
Vol 123 (17) ◽  
pp. 174102 ◽  
Author(s):  
John C. Angus ◽  
Isaac Greber
Keyword(s):  
Identical Composition ◽  
Dielectric Solids

point-Analysis Using the Extrapolation Method in the Analytical Electron microscope

1990 ◽  
Vol 48 (2) ◽  
pp. 430-431
Author(s):  
Zenji Horita ◽  
Ryuzo Nishimachi ◽  
Takeshi Sano ◽  
Minoru Nemoto
Keyword(s):  
Electron Microscope ◽  
Extrapolation Method ◽  
X Ray ◽  
Absorption Correction ◽  
Point Analysis ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Data Points ◽  
Identical Composition ◽  
X Ray Absorption

Absorption correction is often required in quantitative x-ray microanalysis of thin specimens using the analytical electron microscope. For such correction, it is convenient to use the extrapolation method[l] because the thickness, density and mass absorption coefficient are not necessary in the method. The characteristic x-ray intensities measured for the analysis are only requirement for the absorption correction. However, to achieve extrapolation, it is imperative to obtain data points more than two at different thicknesses in the identical composition. Thus, the method encounters difficulty in analyzing a region equivalent to beam size or the specimen with uniform thickness. The purpose of this study is to modify the method so that extrapolation becomes feasible in such limited conditions. Applicability of the new form is examined by using a standard sample and then it is applied to quantification of phases in a Ni-Al-W ternary alloy.The earlier equation for the extrapolation method was formulated based on the facts that the magnitude of x-ray absorption increases with increasing thickness and that the intensity of a characteristic x-ray exhibiting negligible absorption in the specimen is used as a measure of thickness.

Numerical Methods for Analysis of Charged Vacancy Diffusion in Dielectric Solids

2006 ◽  
Author(s):  
John D. Clayton ◽  
Peter W. Chung ◽  
Michael A. Greenfield ◽  
WIlliam D. Nothwang
Keyword(s):  
Numerical Methods ◽  
Vacancy Diffusion ◽  
Dielectric Solids

scholarly journals Mineralization of 3D Osteogenic Model Based on Gelatin-Dextran Hybrid Hydrogel Scaffold Bioengineered with Mesenchymal Stromal Cells: A Multiparametric Evaluation

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3852
Author(s):  
Federica Re ◽  
Luciana Sartore ◽  
Elisa Borsani ◽  
Matteo Ferroni ◽  
Camilla Baratto ◽  
...  
Keyword(s):  
Mesenchymal Stromal Cells ◽  
Stromal Cells ◽  
Bone Repair ◽  
Active Role ◽  
Ionization Mass ◽  
Hydrogel Scaffold ◽  
Hybrid Hydrogel ◽  
Hydrogel Scaffolds ◽  
Human Platelet Lysate ◽  
Identical Composition

Gelatin–dextran hydrogel scaffolds (G-PEG-Dx) were evaluated for their ability to activate the bone marrow human mesenchymal stromal cells (BM-hMSCs) towards mineralization. G-PEG-Dx1 and G-PEG-Dx2, with identical composition but different architecture, were seeded with BM-hMSCs in presence of fetal bovine serum or human platelet lysate (hPL) with or without osteogenic medium. G-PEG-Dx1, characterized by a lower degree of crosslinking and larger pores, was able to induce a better cell colonization than G-PEG-Dx2. At day 28, G-PEG-Dx2, with hPL and osteogenic factors, was more efficient than G-PEG-Dx1 in inducing mineralization. Scanning electron microscopy (SEM) and Raman spectroscopy showed that extracellular matrix produced by BM-hMSCs and calcium-positive mineralization were present along the backbone of the G-PEG-Dx2, even though it was colonized to a lesser degree by hMSCs than G-PEG-Dx1. These findings were confirmed by matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI), detecting distinct lipidomic signatures that were associated with the different degree of scaffold mineralization. Our data show that the architecture and morphology of G-PEG-Dx2 is determinant and better than that of G-PEG-Dx1 in promoting a faster mineralization, suggesting a more favorable and active role for improving bone repair.

Macro-scale description of transient electro-kinetic phenomena over polarizable dielectric solids

2009 ◽  
Vol 620 ◽  
pp. 241-262 ◽  
Author(s):  
G. YOSSIFON ◽  
I. FRANKEL ◽  
T. MILOH
Keyword(s):  
Electric Field ◽  
Electrolyte Solution ◽  
Time Scale ◽  
Temporal Evolution ◽  
Fluid Motion ◽  
Double Layers ◽  
Uniform Field ◽  
Micro Particles ◽  
Macro Scale ◽  
Dielectric Solids

We have studied the temporal evolution of electro-kinetic flows in the vicinity of polarizable dielectric solids following the application of a ‘weak’ transient electric field. To obtain a macro-scale description in the limit of narrow electric double layers (EDLs), we have derived a pair of effective transient boundary conditions directly connecting the electric potentials across the EDL. Within the framework of the above assumptions, these conditions apply to a general transient electro-kinetic problem involving dielectric solids of arbitrary geometry and relative permittivity. Furthermore, the newly derived scheme is applicable to general transient and spatially non-uniform external fields. We examine the details of the physical mechanisms involved in the relaxation of the induced-charging process of the EDL adjacent to polarizable dielectric solids. It is thus established that the time scale characterizing the electrostatic relaxation increases with the dielectric constant of the solid from the Debye time (for the diffusion across the EDL) through the ‘intermediate’ scale (proportional to the product of the respective Debye- and geometric-length scales). Thus, the present rigorous analysis substantiates earlier results largely obtained by heuristic use of equivalent RC-circuit models. Furthermore, for typical values of ionic diffusivity and kinematic viscosity of the electrolyte solution, the latter time scale is comparable to the time scale of viscous relaxation in problems concerning microfluidic applications or micro-particle dynamics. The analysis is illustrated for spherical micro-particles. Explicit results are thus presented for the temporal evolution of electro-osmosis around a dielectric sphere immersed in unbounded electrolyte solution under the action of a suddenly applied uniform field, combining both induced charge and ‘equilibrium’ (fixed charge) contributions to the zeta potential. It is demonstrated that, owing to the time delay of the induced-EDL charging, the ‘equilibrium’ contribution to fluid motion (which is linear in the electric field) initially dominates the (quadratic) ‘induced’ contribution.

scholarly journals A revision of Annularia and Asterophyllites species from the lower Westphalian (Middle Pennsylvanian) of the Maritime Provinces of Canada

2017 ◽  
Vol 53 ◽  
pp. 017-062 ◽  
Author(s):  
Carmen Álvarez-Vázquez ◽  
Robert H. Wagner
Keyword(s):  
Nova Scotia ◽  
New Brunswick ◽  
Western Europe ◽  
Maritime Provinces ◽  
Geographic Ranges ◽  
European Literature ◽  
Scant Attention ◽  
Identical Composition

As part of a larger project to revise the systematics of lower Westphalian floras of Nova Scotia and New Brunswick, the sphenopsid taxa are presently reviewed. We recognize 15 species, of which one, Annularia stopesiae, is new. Detailed synonymy lists allow a refinement of the stratigraphic and geographic ranges of these species. Scant attention has been paid previously to Canadian species in the European literature. For example, Annularia latifolia was described later from Europe as Annularia jongmansii. The identical composition of Westphalian floras from Canada and western Europe is striking.

Les structures annulaires des granites des 'taourirts' en Ahaggar occidental (Sahara)

1963 ◽  
Vol S7-V (5) ◽  
pp. 695-700
Author(s):  
Jean Boissonnas
Keyword(s):  
Grain Size ◽  
Eastern Boundary ◽  
Two Generations ◽  
Ring Structures ◽  
Identical Composition

Abstract A swarm of granite massifs outcrops in the Pharusian structural basin of western Ahaggar (Algeria) not far from the major dislocation marking the eastern boundary of the basin, and separating two distinct areas. The granites appear as ring structures; two phenomena caused these features: the emplacement of several successive porphyroid granites, each one having identical composition but varying in grain size, and the formation of thick rings with relatively alkaline and leucocratic borders. Two generations of massifs are apparent and differ in their alkaline marginal facies, in their complexity, and in their geographic situation. The plutons of western Ahaggar and the subvolcanic structures of Nigeria have certain aspects of their structure in common. Nevertheless, the 'taourirts' are older and less evolved than those of Nigeria.

Macroscopic theory of dielectric solids. I. The model of molecular optics

1977 ◽  
Vol 55 (24) ◽  
pp. 2169-2179 ◽  
Author(s):  
J. E. Sipe
Keyword(s):  
Constitutive Relations ◽  
Pair Correlation ◽  
Finite Size ◽  
Amorphous Solid ◽  
Amorphous Solids ◽  
Uniform Density ◽  
Macroscopic Theory ◽  
Standard Result ◽  
Dielectric Solids ◽  
Spatially Varying

An improved derivation is given of the macroscopic electrodynamic equations for dielectric solids of finite size composed of molecules with a given polarizability, α = α(ω), interacting only via the retarded dipole–dipole coupling. We present a derivation of the constitutive relations for both crystalline and amorphous solids, which is not based on an expansion in powers of α, and in which the radiative reaction forces are carefully taken into account. The spatially varying density and pair correlation function of an amorphous solid, defined with the help of spatial averaging procedures, are shown to satisfy an integral 'counting' relation, which puts a condition on any physically consistent model of an amorphous solid. In the absence of dissipative damping, a medium is shown to be characterized by a real, in general spatially varying, dielectric constant. For solids of uniform density, crystalline or amorphous, we obtain the standard result that inside such a medium light propagates without scattering. For amorphous solids with varying density, the theory forms the basis of the macroscopic theory of light scattering from density in-homogeneities.

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