EXCHANGE BETWEEN METALS AND THEIR IONS IN SOLUTION

1959 ◽  
Vol 37 (1) ◽  
pp. 205-212 ◽  
Author(s):  
Cecil V. King ◽  
Nancy E. McKinney
Keyword(s):  
Experimental Results ◽  
Exchange Current ◽  
Internal Diffusion ◽  
Tracer Method ◽  
Self Diffusion ◽  
Metal Specimen ◽  
Tracer Solution ◽  
Local Cell

The mechanisms by which a metal specimen can acquire radioactivity when immersed in a tracer solution of its own ions are discussed. Consideration is given to the roles of exchange current, adsorption, local cell electrolysis, corrosion, and self-diffusion within the metal. It is shown that exchange current cannot be measured by the tracer method unless conditions are unusually favorable, and that too little attention has been paid to the role of internal diffusion. Some experimental results with silver are presented and the importance of internal diffusion is shown.

Role of Atomic Size and Valence in Bonding and Diffusion at Metal Surfaces

1992 ◽  
Vol 280 ◽  
Author(s):  
Peter J. Feibelman
Keyword(s):  
Diffusion Barrier ◽  
First Principles ◽  
Metal Surfaces ◽  
Experimental Results ◽  
First Principles Calculations ◽  
Atomic Size ◽  
Self Diffusion ◽  
Chemical Concepts ◽  
And Diffusion

ABSTRACTFirst-principles calculations and corresponding experimental results underline the importance of basic chemical concepts in understanding bonding and diffusion of atoms at and on metal surfaces. Examples discussed include the outward relaxation of clean Be(0001), the separation energies of metal-adatom dimers, concerted substitutional self-diffusion on fcc(001) and (110) surfaces, and adsorption and diffusion barrier sites for adatoms near steps.

Transport and fluctuations in nonlinear-dissipative systems: role of interparticle collisions

1999 ◽  
Vol 4 ◽  
pp. 31-86 ◽  
Author(s):  
R. Katilius ◽  
A. Matulionis ◽  
R. Raguotis ◽  
I. Matulionienė
Keyword(s):  
Electric Fields ◽  
Carrier Density ◽  
Experimental Results ◽  
Dissipative Systems ◽  
Doped Semiconductors ◽  
Electron Diffusion ◽  
Electron Collisions ◽  
Electric Noise ◽  
Diffusion Phenomena

The goal of the paper is to overview contemporary theoretical and experimental research of the microwave electric noise and fluctuations of hot carriers in semiconductors, revealing sensitivity of the noise spectra to non-linearity in the applied electric field strength and, especially, in the carrier density. During the last years, investigation of electronic noise and electron diffusion phenomena in doped semiconductors was in a rapid progress. By combining analytic and Monte Carlo methods as well as the available experimental results on noise, it became possible to obtain the electron diffusion coefficients in the range of electric fields where inter-electron collisions are important and Price’s relation is not necessarily valid. Correspondingly, a special attention to the role of inter-electron collisions and of the non-linearity in the carrier density while shaping electric noise and diffusion phenomena in the non-equilibrium states will be paid. The basic and up-to-date information will be presented on methods and advances in this contemporary field - the field in which methods of non-linear analytic and computational analysis are indispensable while seeking coherent understanding and interpretation of experimental results.

Diffusion Mechanisms in Sige Alloys

1999 ◽  
Vol 568 ◽  
Author(s):  
Arthur F.W. Willoughby ◽  
Janet M. Bonar ◽  
Andrew D.N. Paine
Keyword(s):  
Diffusion Processes ◽  
Dopant Diffusion ◽  
Elemental Silicon ◽  
Self Diffusion ◽  
Si Substrates ◽  
Marker Layer ◽  
Diffusion Mechanisms ◽  
Silicon And Germanium ◽  
Charged Defects

ABSTRACTInterest in diffusion processes in SiGe alloys arises from their potential in HBT's, HFET's, and optoelectronics devices, where migration over distances as small as a few nanometres can be significant. Successful modelling of these processes requires a much improved understanding of the mechanisms of self- and dopant diffusion in the alloy, although recent progress has been made. It is the purpose of this review to set this in the context of diffusion processes in elemental silicon and germanium, and to identify how this can help to elucidate behaviour in the alloy. Firstly, self diffusion processes are reviewed, from general agreement that self-diffusion in germanium is dominated by neutral and acceptor vacancies, to the position in silicon which is still uncertain. Germanium diffusion in silicon, however, appears to be via both vacancy and interstitial processes, and in the bulk alloy there is evidence for a change in dominant mechanism at around 35 percent germanium. Next, a review of dopant diffusion begins with Sb, which appears to diffuse in germanium by a mechanism similar to self-diffusion, and in silicon via monovacancies also, from marker layer evidence. In SiGe, the effects of composition and strain in epitaxial layers on Si substrates are also consistent with diffusion via vacancies, but questions still remain on the role of charged defects. The use of Sb to monitor vacancy effects such as grown-in defects by low temperature MBE, are discussed. Lastly, progress in assessing the role of vacancies and interstitials in the diffusion of boron is reviewed, which is dominated by interstitials in silicon-rich alloys, but appears to change to domination by vacancies at around 40 percent germanium, although studies in pure germanium are greatly needed.

Some Considerations on Confined Water: The Thermal Behavior of Transport Properties in Water-Glycerol and Water-Methanol Mixtures

MRS Advances ◽  
2016 ◽  
Vol 1 (26) ◽  
pp. 1891-1902 ◽  
Author(s):  
Francesco Mallamace ◽  
Carmelo Corsaro ◽  
Domenico Mallamace ◽  
Cirino Vasi ◽  
Sebastiano Vasi ◽  
...  
Keyword(s):  
Hydrophobic Interactions ◽  
Molar Fraction ◽  
Relaxation Times ◽  
Confined Water ◽  
Self Diffusion ◽  
Excess Value ◽  
Water Glycerol ◽  
System Properties ◽  
Dynamical Crossover

ABSTRACTWe discuss recent literature data on the relaxation times (the primary tα), viscosity, and self-diffusion in water-glycerol and water-methanol mixtures across a wide temperature range from the stable water phase to the deep supercooled regime (373–147K). In particular, to clarify the role of hydrophilicity interactions (the hydrogen bonds) and hydrophobic interactions we study the mixture in terms of the water molar fraction (XW) with fixed temperatures at 5K steps across the entire composition range, and we find a marked deviation from the ideal thermodynamic behavior of the transport functions. This deviation is strongly T and XW dependent and spans values that range from two orders of magnitude at the highest temperature to more than five in the deeply supercooled regime (more precisely, at ≃200K). We analyze these deviations in terms of how the measured values differ from ideal values and find that the hydrogen-bonding water network dominates system properties up to XW = 0.3. We also examine an Arrhenius plot of the maximum excess value (Δtα(T) vs. 1/T) and find two significant changes due to water: one at the dynamical crossover temperature (TL ≃ 225K, i.e., the locus of the Widom line), and one at T ≃ 315K (the water isothermal compressibility χT minimum).

Role of Ce2Zr3O10 Phase on the Microstructure and Fracture Toughness of ZTA Composites

2016 ◽  
Vol 840 ◽  
pp. 57-60 ◽  
Author(s):  
Nik Akmar Rejab ◽  
Zhwan Dilshad Ibrahim Sktani ◽  
Afifah Mohd Ali ◽  
Zainal Arifin Ahmad
Keyword(s):  
Fracture Toughness ◽  
Experimental Results ◽  
Mixing Process ◽  
Transformation Toughening ◽  
Simple Route ◽  
Zirconia Toughened Alumina

Despite the impressive development in understanding transformation toughening, tailoring the toughness of zirconia toughened alumina (ZTA) ceramics remained a major challenge. In our research, a simple route based on the powders mixing process of ZTA powders with varying CeO2 additions (0 - 10 wt.%) is developed to investigate this issue. The experimental results clearly reveal that the fracture toughness of ZTA ceramics can be tailored by mixing of ZTA starting powders.

scholarly journals Libet’s experiments and the problem of free will

2016 ◽  
Vol 59 (4) ◽  
pp. 23-29
Author(s):  
Andrea Berber
Keyword(s):  
Free Will ◽  
Experimental Results ◽  
Readiness Potential ◽  
Real Effect

The purpose of this paper is to give an answer to the question of the extent to which Libet?s experiments are helping to solve the problem of free will. Relevance of Libet?s experimental results for the problem of free will is contested by the multitude of complaints. These complaints can be divided into three categories: methodological objections, conceptual objections and complaints regarding the interpretation of the role of readiness potential. I am trying to show that only objections that belong to the last group have a real effect. I conclude that Libet?s experiments while providing significant incentives and suggestions for further research did not contribute to solving the problem of free will.

scholarly journals Cell proliferation controls body size growth, tentacle morphogenesis, and regeneration in hydrozoan jellyfish Cladonema pacificum

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7579 ◽  
Author(s):  
Sosuke Fujita ◽  
Erina Kuranaga ◽  
Yu-ichiro Nakajima
Keyword(s):  
Cell Proliferation ◽  
Body Size ◽  
Environmental Changes ◽  
Size Control ◽  
Cellular Mechanisms ◽  
Proliferating Cells ◽  
Size Growth ◽  
Local Cell ◽  
Proliferating Cell

Jellyfish have existed on the earth for around 600 million years and have evolved in response to environmental changes. Hydrozoan jellyfish, members of phylum Cnidaria, exist in multiple life stages, including planula larvae, vegetatively-propagating polyps, and sexually-reproducing medusae. Although free-swimming medusae display complex morphology and exhibit increase in body size and regenerative ability, their underlying cellular mechanisms are poorly understood. Here, we investigate the roles of cell proliferation in body-size growth, appendage morphogenesis, and regeneration using Cladonema pacificum as a hydrozoan jellyfish model. By examining the distribution of S phase cells and mitotic cells, we revealed spatially distinct proliferating cell populations in medusae, uniform cell proliferation in the umbrella, and clustered cell proliferation in tentacles. Blocking cell proliferation by hydroxyurea caused inhibition of body size growth and defects in tentacle branching, nematocyte differentiation, and regeneration. Local cell proliferation in tentacle bulbs is observed in medusae of two other hydrozoan species, Cytaeis uchidae and Rathkea octopunctata, indicating that it may be a conserved feature among hydrozoan jellyfish. Altogether, our results suggest that hydrozoan medusae possess actively proliferating cells and provide experimental evidence regarding the role of cell proliferation in body-size control, tentacle morphogenesis, and regeneration.

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