Driving forces behind the distortion of one-dimensional monatomic chains: Peierls theorem revisited

A one-dimensional model of an elasto-plastic theory of dislocation fields is developed to model planar dislocation core structures. This theory is based on the evolution of polar dislocation densities. The motion of dislocations is accounted for by a dislocation density transport equation where dislocation velocities derive from Peach-Koehler type driving forces. Initial narrow dislocation cores are shown to spread out by transport under their own internal stress field and no relaxed configuration is found. A restoring stress of the lattice is necessary to stop this infinite relaxation and it is derived from periodic sinusoidal energy of the crystal. When using the Peierls sinusoidal potential, a compact equilibrium core configuration corresponding to the Peierls analytical solution is obtained. The model is then extended to use generalized planar stacking fault energies as an input and is applied to the determination of properties of planar dislocation cores in crystalline materials. Dissociations of edge and screw dislocation cores in basal and prismatic planes of Zirconium are shown.

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Effects on electrostatic fields excited by radio-frequency waves in a bounded plasma due to the ponderomotive force

Journal of Plasma Physics ◽

10.1017/s0022377800024223 ◽

1992 ◽

Vol 47 (2) ◽

pp. 271-279

Author(s):

C. R. Gutiérrez-Tapia

Keyword(s):

Radio Frequency ◽

Driving Forces ◽

Ponderomotive Force ◽

Plasma Layer ◽

Physical Processes ◽

One Dimensional ◽

Electrostatic Fields ◽

Bounded Plasma ◽

Linearly Polarized ◽

Radio Frequency Waves

A one-dimensional model explaining the mechanism of excitation of electrostatic fields by linearly polarized radio-frequency waves in a plasma layer is presented. It is shown that the ponderomotive and driving forces influence this process strongly; however, these forces act at different times when a wave front passes through the plasma. We consider a semi-infinite plasma, and a plasma layer with and without current. It is observed that near to the plasma boundaries, where the electric field is large, there arise amplitude field oscillations, which are slowly exponentially damped in space. It is shown that the physical processes arising near the boundary x = L are similar to those at the boundary x = 0. It is seen that the current in the plasma block excitation at the boundary x = L.

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Mathematical models of arterial transmural transport

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1985.248.2.h240 ◽

1985 ◽

Vol 248 (2) ◽

pp. H240-H263 ◽

Cited By ~ 12

Author(s):

D. L. Fry

Keyword(s):

Driving Forces ◽

Water Flux ◽

Element Model ◽

Parameter Estimates ◽

Convective Velocity ◽

Reversible Binding ◽

One Dimensional ◽

Coefficients Of Variation ◽

The One ◽

Molecular Sieving

A finite-element model (FEM) and corresponding five-parameter analytical model (AM) were derived to study the one-dimensional transport of chemically reactive macro-molecules across (x) arterial tissue. Derivations emphasize chemical activity [a(x)], its gradient, and water flux as driving forces for chemical reactions and transport. The AM was fitted to 28 measured 125I-albumin transmural concentration [c(x)] curves giving parameter estimates of diffusivity (DA), convective velocity (nu A), and so on as functions of pressure (P), location (z) along the vessel, etc. The FEM was used to study 1) intimal-medial a(x) associated with molecular sieving and medial edema, 2) reversible binding, and 3) errors of AM in analysis of c(x). Results are as follows. Average relative error for the 28 AM fits was 5.3%. Only estimates of DA and nu A had acceptable coefficients of variation. DA (approximately 0.10 X 10(-7) cm2 X s-1) decreased with P, increased with z to a maximum, and then decreased; nu A was approximately proportional to P (approximately 0.12 X 10(-7) cm X s-1 X mmHg-1) and decreased slightly with z; distribution coefficient (epsilon F) decreased with z and was smaller for serum than for simple albumin reagent. Assumed boundary conditions for AM were associated with approximately 1.4% error in AM c(x). Parameter estimates were sensitive to wall inhomogeneity, e.g., approximately 15% error. In conclusion, the AM and FEM simulated measured c(x) well; the FEM is useful for study of mechanisms, experimental designs, and AM errors; trends of AM parameter estimates suggest dependence on P, z, and composition of reagent for further FEM and experimental study.

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One-Dimensional, Transient Model of Heat, Mass, and Charge Transfer in a Proton Exchange Membrane

10.1115/imece2001/aes-23652 ◽

2001 ◽

Author(s):

Brandon Eaton ◽

Michael R. von Spakovsky ◽

Michael W. Ellis ◽

Douglas J. Nelson ◽

Benoit Olsommer ◽

...

Keyword(s):

Fuel Cell ◽

Proton Exchange Membrane ◽

Driving Forces ◽

Water Concentration ◽

Proton Exchange ◽

Heat Fluxes ◽

Transient Model ◽

One Dimensional ◽

Proton Potential ◽

Exchange Membrane

Abstract A transient, one-dimensional, model of the membrane of a proton exchange membrane fuel cell is presented. The role of the membrane is to transport protons from the anode to cathode of the fuel cell while preventing the transport of other reactants. The membrane is modeled assuming mono-phase, multi-species flow. For water transport, the principle driving forces modeled are a convective force, an osmotic force (i.e. diffusion), and an electric force. The first of these results from a pressure gradient, the second from a concentration gradient, and the third from the migration of protons from anode to cathode and their effect (drag) on the dipole water molecules. Equations are developed for the conservation of protons and water, the conservation of thermal energy, and the variation of proton potential within the membrane. The model is solved using a fully implicit finite difference approach. Results showing the effects of current density, pressure gradients, water and heat fluxes, and fuel cell start-up on water concentration, temperature, and proton potential across the membrane are presented.

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Facile synthesis and formation mechanism of uniform antimony nanotubes

Functional Materials Letters ◽

10.1142/s1793604717500643 ◽

2017 ◽

Vol 10 (05) ◽

pp. 1750064 ◽

Cited By ~ 1

Author(s):

Xinwei Wang ◽

Shichen Su ◽

Dan Fang ◽

Haoran Zhang ◽

Dengkui Wang ◽

...

Keyword(s):

Formation Mechanism ◽

Self Assembly ◽

Driving Forces ◽

Reduction Process ◽

Rhombohedral Phase ◽

Temperature Dependent ◽

One Dimensional ◽

Good Crystallinity ◽

Template Free ◽

Average Size

One-dimensional tubular antimony (Sb) nanomaterials were successfully synthesized via a facile template-free solvothermal reduction process. These as-synthesized Sb nanotubes exhibited a middle-hollow, multi-walled, open-ended structures with the average size of lengths and diameters for [Formula: see text][Formula: see text]nm. Also, they show the rhombohedral phase and good crystallinity in nature. Based on the crystal structures and morphologies evolution of Sb nanomaterials by the temperature-dependent reactions, the formation mechanism of Sb nanotubes has been proposed to be that the nanosized clusters nucleated first and then self-assembly aggregated into thin nanosheets and finally rolled into the nanotubes through some driving forces, namely, a rolling-up mechanism.

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A one-dimensional self-gravitating stellar gas

Symposium - International Astronomical Union ◽

10.1017/s0074180900105261 ◽

1966 ◽

Vol 25 ◽

pp. 46-48 ◽

Cited By ~ 2

Author(s):

M. Lecar

Keyword(s):

Gravitational Field ◽

Phase Space ◽

Motion Picture ◽

Space Distribution ◽

Two Dimensional ◽

One Dimensional ◽

Phase Space Distribution ◽

Dimensional Phase Space ◽

The Mean

“Dynamical mixing”, i.e. relaxation of a stellar phase space distribution through interaction with the mean gravitational field, is numerically investigated for a one-dimensional self-gravitating stellar gas. Qualitative results are presented in the form of a motion picture of the flow of phase points (representing homogeneous slabs of stars) in two-dimensional phase space.

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Electron-Mirror Microscopic Aspects of Ferroelectric Domains of BaTiO3 And Ca2Sr (C2H5CO2)6

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100069387 ◽

1970 ◽

Vol 28 ◽

pp. 478-479

Author(s):

Teruo Someya ◽

Jinzo Kobayashi

Keyword(s):

Surface Layer ◽

Electric Fields ◽

Quantitative Study ◽

Recent Progress ◽

Ferroelectric Domain ◽

Resolving Power ◽

Surface Pattern ◽

Crystal Surfaces ◽

One Dimensional ◽

Ferroelectric Domains

Recent progress in the electron-mirror microscopy (EMM), e.g., an improvement of its resolving power together with an increase of the magnification makes it useful for investigating the ferroelectric domain physics. English has recently observed the domain texture in the surface layer of BaTiO3. The present authors ) have developed a theory by which one can evaluate small one-dimensional electric fields and/or topographic step heights in the crystal surfaces from their EMM pictures. This theory was applied to a quantitative study of the surface pattern of BaTiO3).

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Structure and function of neural networks in the retina

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100102213 ◽

1988 ◽

Vol 46 ◽

pp. 26-27

Author(s):

Peter Sterling

Keyword(s):

Ganglion Cells ◽

Three Dimensional ◽

Structure And Function ◽

Synaptic Connections ◽

Visual Axis ◽

One Dimensional ◽

Cat Retina ◽

Ultrathin Sections ◽

And Function ◽

Insight Into

The synaptic connections in cat retina that link photoreceptors to ganglion cells have been analyzed quantitatively. Our approach has been to prepare serial, ultrathin sections and photograph en montage at low magnification (˜2000X) in the electron microscope. Six series, 100-300 sections long, have been prepared over the last decade. They derive from different cats but always from the same region of retina, about one degree from the center of the visual axis. The material has been analyzed by reconstructing adjacent neurons in each array and then identifying systematically the synaptic connections between arrays. Most reconstructions were done manually by tracing the outlines of processes in successive sections onto acetate sheets aligned on a cartoonist's jig. The tracings were then digitized, stacked by computer, and printed with the hidden lines removed. The results have provided rather than the usual one-dimensional account of pathways, a three-dimensional account of circuits. From this has emerged insight into the functional architecture.

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Solute redistribution during in-situ irradiation of alloys in the high voltage electron microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100108994 ◽

1978 ◽

Vol 36 (1) ◽

pp. 370-371

Author(s):

P. R. Okamoto ◽

N.Q. Lam ◽

R. L. Lyles

Keyword(s):

Electron Microscope ◽

High Voltage ◽

Driving Forces ◽

Solute Diffusion ◽

Solute Redistribution ◽

Voltage Electron ◽

High Voltage Electron Microscope ◽

High Voltage Electron ◽

Thin Foils ◽

Solute Atoms

During irradiation of thin foils in a high voltage electron microscope (HVEM) defect gradients will be set up between the foil surfaces and interior. In alloys defect gradients provide additional driving forces for solute diffusion since any preferential binding and/or exchange between solute atoms and mobile defects will couple a net flux of solute atoms to the defect fluxes. Thus, during irradiation large nonequilibrium compositional gradients can be produced near the foil surfaces in initially homogeneous alloys. A system of coupled reaction-rate and diffusion equations describing the build up of mobile defects and solute redistribution in thin foils and in a semi-infinite medium under charged-particle irradiation has been formulated. Spatially uniform and nonuniform damage production rates have been used to model solute segregation under electron and ion irradiation conditions.An example calculation showing the time evolution of the solute concentration in a 2000 Å thick foil during electron irradiation is shown in Fig. 1.

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