scholarly journals Adiabatic Electronic Motion in Forming Covalent Bond

2018 ◽  
Author(s):  
Michihiro Okuyama ◽  
Fumihiko Sakata
Keyword(s):  
Current Density ◽  
Covalent Bond ◽  
Displacement Current ◽  
Dynamical Process ◽  
Electronic Density ◽  
Electronic Current ◽  
Electronic Motion ◽  
Null Value ◽  
Current Densities ◽  
The One

<div>In studying a dynamical process of the chemical reaction, it is decisive to get appropriate information from an electronic current density. To this end, we divide one-body electronic density into a couple of densities, that is, an electronic sharing density and an electronic contraction density. Since the one-body electronic current density defi ned directly through the microscopic electronic wave function gives null value under the Born-Oppenheimer molecular dynamics, we propose to employ the Maxwell's displacement current density de fined by means of the one-body electronic density obtained under the same approximation. Applying the electronic sharing and the electronic contraction current densities to a hydrogen molecule, we show these densities give important physical quantities for analyzing a dynamical process of the covalent bond.</div>

scholarly journals Adiabatic Electronic Motion in Forming Covalent Bond

2018 ◽  
Author(s):  
Michihiro Okuyama ◽  
Fumihiko Sakata
Keyword(s):  
Current Density ◽  
Covalent Bond ◽  
Displacement Current ◽  
Dynamical Process ◽  
Electronic Density ◽  
Electronic Current ◽  
Electronic Motion ◽  
Null Value ◽  
Current Densities ◽  
The One

<div>In studying a dynamical process of the chemical reaction, it is decisive to get appropriate information from an electronic current density. To this end, we divide one-body electronic density into a couple of densities, that is, an electronic sharing density and an electronic contraction density. Since the one-body electronic current density defi ned directly through the microscopic electronic wave function gives null value under the Born-Oppenheimer molecular dynamics, we propose to employ the Maxwell's displacement current density de fined by means of the one-body electronic density obtained under the same approximation. Applying the electronic sharing and the electronic contraction current densities to a hydrogen molecule, we show these densities give important physical quantities for analyzing a dynamical process of the covalent bond.</div>

Electron Charge and Current Densities, the Geometrie Phase and Cellular Automata

1993 ◽  
Vol 48 (1-2) ◽  
pp. 134-136
Author(s):  
N. Sukumar ◽  
B. M. Deb ◽  
Harjinder Singh
Keyword(s):  
Current Density ◽  
Electron System ◽  
Time Dependent ◽  
Gauge Potential ◽  
Electronic Charge ◽  
Electronic Density ◽  
Electronic Current ◽  
Finite Set ◽  
The Many ◽  
Electronic Density Distribution

Some consequences of the quantum fluid dynamics formulation are discussed for excited states of atoms and molecules and for time-dependent processes. It is shown that the conservation of electronic current density j(r) allows us to manufacture a gauge potential for each excited state of an atom, molecule or atom in a molecule. This potential gives rise to a tube of magnetic flux carried around by the many-electron system. In time-dependent situations, the evolution of the electronic density distribution can be followed with simple, site-dependent cellular automaton (CA) rules. The CA consists of a lattice of sites, each with a finite set of possible values, here representing finite localized elements of electronic charge and current density (since the charge density rno longer suffices to fully characterize a time-dependent system, it needs to be supplemented with information about the current density j).Our numerical results are presented elsewhere and further developmentis in progress.

Facet Topography and Dislocation Structure as a Possible Source for Electrical Heterogeneity in [001] TILT Bicrystals of YBa2Cu3O7-δ

1996 ◽  
Vol 54 ◽  
pp. 338-339
Author(s):  
I-Fei Tsu ◽  
D.L. Kaiser ◽  
S.E. Babcock
Keyword(s):  
Grain Boundary ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Electromagnetic Properties ◽  
Length Scale ◽  
Density Values ◽  
Current Densities ◽  
Applied Fields ◽  
A Current

A current theme in the study of the critical current density behavior of YBa2Cu3O7-δ (YBCO) grain boundaries is that their electromagnetic properties are heterogeneous on various length scales ranging from 10s of microns to ˜ 1 Å. Recently, combined electromagnetic and TEM studies on four flux-grown bicrystals have demonstrated a direct correlation between the length scale of the boundaries’ saw-tooth facet configurations and the apparent length scale of the electrical heterogeneity. In that work, enhanced critical current densities are observed at applied fields where the facet period is commensurate with the spacing of the Abrikosov flux vortices which must be pinned if higher critical current density values are recorded. To understand the microstructural origin of the flux pinning, the grain boundary topography and grain boundary dislocation (GBD) network structure of [001] tilt YBCO bicrystals were studied by TEM and HRTEM.

Electron-beam damage of oxides at high current densities

1989 ◽  
Vol 47 ◽  
pp. 634-635
Author(s):  
M. R. McCartney ◽  
J. K. Weiss ◽  
David J. Smith
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Current Density ◽  
Transition Metal Oxides ◽  
Time Resolved ◽  
Rapid Acquisition ◽  
Resolution Electron ◽  
Current Densities ◽  
Electron Stimulated Desorption ◽  
Channel Analyzer

It is well-known that electron-beam irradiation within the electron microscope can induce a variety of surface reactions. In the particular case of maximally-valent transition-metal oxides (TMO), which are susceptible to electron-stimulated desorption (ESD) of oxygen, it is apparent that the final reduced product depends, amongst other things, upon the ionicity of the original oxide, the energy and current density of the incident electrons, and the residual microscope vacuum. For example, when TMO are irradiated in a high-resolution electron microscope (HREM) at current densities of 5-50 A/cm2, epitaxial layers of the monoxide phase are found. In contrast, when these oxides are exposed to the extreme current density probe of an EM equipped with a field emission gun (FEG), the irradiated area has been reported to develop either holes or regions almost completely depleted of oxygen. ’ In this paper, we describe the responses of three TMO (WO3, V2O5 and TiO2) when irradiated by the focussed probe of a Philips 400ST FEG TEM, also equipped with a Gatan 666 Parallel Electron Energy Loss Spectrometer (P-EELS). The multi-channel analyzer of the spectrometer was modified to take advantage of the extremely rapid acquisition capabilities of the P-EELS to obtain time-resolved spectra of the oxides during the irradiation period. After irradiation, the specimens were immediately removed to a JEM-4000EX HREM for imaging of the damaged regions.

scholarly journals Effect of Plating Current Density on the Ball-On-Disc Wear of Sn-Plated Ni Coatings on Cu Foils

Coatings ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 56
Author(s):  
Ashutosh Sharma ◽  
Byungmin Ahn
Keyword(s):  
Current Density ◽  
Wear Loss ◽  
Wear Properties ◽  
Friction Behavior ◽  
Track Geometry ◽  
Cu Substrates ◽  
Current Densities ◽  
The Impact ◽  
Sliding Distance ◽  
Ball On Disc

Metallic and alloyed coatings are used widely in several decorative and technology-based applications. In this work, we selected Sn coatings plated on Cu substrates for joining applications. We employed two different plating baths for the fabrication of Sn and Ni coatings: acidic stannous sulfate for Sn and Watts bath for Ni layer. The plating current densities were varied from 100–500 mA/cm2. Further, the wear and friction behavior of the coatings were studied using a ball-on-disc apparatus under dry sliding conditions. The impact of current density was studied on the morphology, wear, and coefficient of friction (COF) of the resultant coatings. The wear experiments were done at various loads from 2–10 N. The sliding distance was fixed to 7 m. The wear loss was quantified in terms of the volume of the track geometry (width and depth of the tracks). The results indicate that current density has an important role in tailoring the composition and morphology of coatings, which affects the wear properties. At higher loads (8–10 N), Sn coatings on Ni/Cu had higher volume loss with a stable COF due to a mixed adhesive and oxidative type of wear mechanism.

Chronic receptor-mediated activation of Gi/o proteins alters basal t-tubular and sarcolemmal L-type Ca2+ channel activity through phosphatases in heart failure

2012 ◽  
Vol 302 (8) ◽  
pp. H1645-H1654 ◽  
Author(s):  
Toshihide Kashihara ◽  
Tsutomu Nakada ◽  
Hisashi Shimojo ◽  
Miwa Horiuchi-Hirose ◽  
Simmon Gomi ◽  
...  
Keyword(s):  
Heart Failure ◽  
Current Density ◽  
Ventricular Myocytes ◽  
Heterotrimeric G Proteins ◽  
Channel Activity ◽  
Open Probability ◽  
Current Densities ◽  
Fractional Shortening ◽  
Pp2a Inhibitor

L-type Ca2+ channels (LTCCs) play an essential role in the excitation-contraction coupling of ventricular myocytes. We previously found that t-tubular (TT) LTCC current density was halved by the activation of protein phosphatase (PP)1 and/or PP2A, whereas surface sarcolemmal (SS) LTCC current density was increased by the inhibition of PP1 and/or PP2A activity in failing ventricular myocytes of mice chronically treated with isoproterenol (ISO mice). In the present study, we examined the possible involvement of inhibitory heterotrimeric G proteins (Gi/o) in these abnormalities by chronically administrating pertussis toxin (PTX) to ISO mice (ISO + PTX mice). Compared with ISO mice, ISO + PTX mice exhibited significantly higher fractional shortening of the left ventricle. The expression level of Gαi2 proteins was not altered by the treatment of mice with ISO and/or PTX. ISO + PTX myocytes had normal TT and SS LTCC current densities because they had higher and lower availability and/or open probability of TT and SS LTCCs than ISO myocytes, respectively. A selective PKA inhibitor, H-89, did not affect LTCC current densities in ISO + PTX myocytes. A selective PP2A inhibitor, fostriecin, did not affect SS or TT current density in control or ISO + PTX myocytes but significantly increased TT but not SS LTCC current density in ISO myocytes. These results indicate that chronic receptor-mediated activation of Gi/o in vivo decreases basal TT LTCC activity by activating PP2A and increases basal SS LTCC activity by inhibiting PP1 without modulating PKA in heart failure.

A Real-Time AC/DC Measurement Technique for Assessment of AC Corrosion of Buried Pipelines

2012 ◽  
Author(s):  
Cindy X. Su ◽  
Luyao Xu ◽  
Frank Y. Cheng
Keyword(s):  
Real Time ◽  
Current Density ◽  
Steel Surface ◽  
Steel Corrosion ◽  
Buried Pipelines ◽  
Total Potential ◽  
Ac Current ◽  
Potential Alternative ◽  
Current Densities ◽  
Ac Interference

In this work, a real-time AC/DC signal data acquisition (DAQ) technique was developed, which is capable of separating the DC and AC potential components from the recorded total potential, providing mechanistic information about the steel corrosion in the presence of AC interference. It was found that the corrosion of the steel is enhanced by the applied AC current density from 0 to 400 A/m2. With the further increase to 600 A/m2 and 800 A/m2, the corrosion rate of the steel decreases, which is attributed to passivation of the steel at sufficiently high AC current densities, and a compact film is formed on the steel surface. Moreover, the derived mathematic relationships between AC potential and AC current density provides a potential alternative to determine AC current density on pipelines based on measurements of AC potential in the field.

Polyaniline: Influence of Polymerization Current Density

1994 ◽  
Vol 369 ◽  
Author(s):  
Steen Skaarup ◽  
L.M.W.K. Gunaratne ◽  
Keld West ◽  
Birgit Zachau-Christiansen
Keyword(s):  
Cyclic Voltammetry ◽  
Current Density ◽  
High Current Density ◽  
Electrochemical Polymerization ◽  
Regular Structure ◽  
Spectral Lines ◽  
Complex Nature ◽  
Cyclic Voltammograms ◽  
Layer By Layer ◽  
Current Densities

AbstractPolyaniline has been synthesized in propylene carbonate by galvanostatic electrochemical polymerization at current densities between 16 and 1000 μA/cm2. Earlier results for polypyrrole have shown that low and high current density films have different properties: The films synthesized at low current density have a higher conjugation length and a more regular structure. The corresponding effect in PANI has been investigated by cyclic voltammetry and UV/visible spectroscopy. Simultaneous measurement of cyclic voltammograms and the absorbtion of selected spectral lines is used because of the complex nature of the PANI system which involves several redox systems as well as forms differing in the degree of protonation and morphology.The main result is that the method of galvanostatic synthesis at low current densities (-16 μA/cm2) produces polyaniline polymers of different, more conjugated and more regular structure than those prepared at higher current densities. The standard method of in situ layer-by-layer polymerization of conducting polymers during cyclic voltammetry often results in uncontrolled and unmeasured current densities of 0.5-2 mA/cm2 which produces a film that probably has a less regular structure containing more deviations from ideality.

NMR Investigation of n-Alkylamine Self-Organization Along the Sidewalls of Single-Wall Carbon Nanotubes (SWNTs)

2004 ◽  
Vol 858 ◽  
Author(s):  
Sang-Yong Ju ◽  
Marcel Utz ◽  
Fotios Papadimitrakopoulos
Keyword(s):  
Carbon Nanotubes ◽  
Density Of States ◽  
Single Wall Carbon Nanotubes ◽  
Aliphatic Chain ◽  
Community Based ◽  
Electronic Density ◽  
Single Wall Carbon ◽  
Bulk Separation ◽  
The One ◽  
Differential Solubility

Single wall carbon nanotubes (SWNTs) have drawn considerable attention from the scientific community based on their potentially unique 1-D electronic and optical properties as well as mechanical properties. These characteristics result from the one dimensional quantum wire structure of CNTs, which have the spike-like van Hove singularities (vHs) in the electronic density of states. The detailed shape of the density of states function depends sensitively on CNT type semiconducting (sem-) versus metallic (met-)), diameter and chirality. Using the preferential affinity of amines towards sem -SWNTs, our group has been able to attain bulk separation by type based on a differential solubility of SWNTs according to the amine organization interaction on the nanotube surface. It has been argued that stable dispersions of sem -SWNTs with surfactant-amines originate from the organization of the aliphatic chain along the nanotube sidewalls, along with a small amount of zwitterions. The separation of sem-enriched SWNTs assisted by octadecylamine (ODA) had been depicted in the form of either small amount of zwitterionic interaction between carboxylic acid groups of acid-purified SWNTs or the physisorption on the SWNTs sidewall, leaving met -SWNTs in the precipitate.

Structural Properties of Ni-Co Electroplated Coatings Studied by X-Ray Micro-Beam

2014 ◽  
Vol 635 ◽  
pp. 204-207 ◽  
Author(s):  
Ondrej Milkovič ◽  
Mária Hagarová ◽  
Jana Michaliková ◽  
Matúš Horváth
Keyword(s):  
Synchrotron Radiation ◽  
Structural Properties ◽  
Current Density ◽  
Deposition Process ◽  
Transmission Mode ◽  
Structure Parameters ◽  
Electrodeposition Process ◽  
Cu Substrate ◽  
X Ray ◽  
Current Densities

In this article we focused to influence of current density on the structure parameters evaluated by microdiffraction experiment in transmission mode using synchrotron radiation. For this purpose the coatings of Ni-Co alloy were deposited on the Cu substrate using different current densities during the electrodeposition process. The results of the microdiffraction experiment showed the structure uniformity of the coatings along their thickness, as well as changes in the structure parameters depending on the used current density during the deposition process.

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