Association–Dissociation Dynamics of Ionic Electrolytes in Low Dielectric Medium

2021 ◽  
Author(s):  
Deborin Ghosh ◽  
Sushil S. Sakpal ◽  
Srijan Chatterjee ◽  
Samadhan H. Deshmukh ◽  
Hyejin Kwon ◽  
...  
Keyword(s):  
Dielectric Medium ◽  
Low Dielectric ◽  
Dissociation Dynamics

scholarly journals Computing Protein pKas Using the TABI Poisson–Boltzmann Solver

2020 ◽  
pp. 2042006
Author(s):  
Jiahui Chen ◽  
Jingzhen Hu ◽  
Yongjia Xu ◽  
Robert Krasny ◽  
Weihua Geng
Keyword(s):  
Boltzmann Distribution ◽  
Dielectric Medium ◽  
Boundary Integral ◽  
Acid Dissociation ◽  
Low Dielectric ◽  
Poisson Boltzmann ◽  
Computing Procedure ◽  
Poisson Boltzmann Equation ◽  
High Dielectric ◽  
Electrostatic Calculations

A common approach to computing protein pKas uses a continuum dielectric model in which the protein is a low dielectric medium with embedded atomic point charges, the solvent is a high dielectric medium with a Boltzmann distribution of ionic charges, and the pKa is related to the electrostatic free energy which is obtained by solving the Poisson–Boltzmann equation. Starting from the model pKa for a titrating residue, the method obtains the intrinsic pKa and then computes the protonation probability for a given pH including site–site interactions. This approach assumes that acid dissociation does not affect protein conformation aside from adding or deleting charges at titratable sites. In this work, we demonstrate our treecode-accelerated boundary integral (TABI) solver for the relevant electrostatic calculations. The pKa computing procedure is enclosed in a convenient Python wrapper which is publicly available at the corresponding author’s website. Predicted results are compared with experimental pKas for several proteins. Among ongoing efforts to improve protein pKa calculations, the advantage of TABI is that it reduces the numerical errors in the electrostatic calculations so that attention can be focused on modeling assumptions.

scholarly journals Through-Space Ultrafast Photoinduced Electron Transfer Dynamics of a C70-Encapsulated Bisporphyrin Covalent Organic Polyhedron in a Low-Dielectric Medium

2017 ◽  
Vol 139 (12) ◽  
pp. 4286-4289 ◽  
Author(s):  
Michael Ortiz ◽  
Sung Cho ◽  
Jens Niklas ◽  
Seonah Kim ◽  
Oleg G. Poluektov ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Photoinduced Electron Transfer ◽  
Dielectric Medium ◽  
Low Dielectric

Electrochemistry in a low dielectric medium in the presence of a crown ether. Suppression of anodic dissolution of metal electrodes

1980 ◽  
Vol 111 (2-3) ◽  
pp. 391-395 ◽  
Author(s):  
Seiichiro Nakabayashi ◽  
Akira Fujishima ◽  
Kenichi Honda
Keyword(s):  
Crown Ether ◽  
Anodic Dissolution ◽  
Dielectric Medium ◽  
Metal Electrodes ◽  
Low Dielectric

scholarly journals A Simple Complex on the Verge of Breakdown: Isolation of the Elusive Cyanoformate Ion

Science ◽  
2014 ◽  
Vol 344 (6179) ◽  
pp. 75-78 ◽  
Author(s):  
Luke J. Murphy ◽  
Katherine N. Robertson ◽  
Scott G. Harroun ◽  
Christa L. Brosseau ◽  
Ulrike Werner-Zwanziger ◽  
...  
Keyword(s):  
Active Site ◽  
Theoretical Calculations ◽  
Acc Oxidase ◽  
Dielectric Medium ◽  
Solution Stability ◽  
Stability Studies ◽  
Simple Complex ◽  
Low Dielectric ◽  
Dielectric Media ◽  
Iron Center

Why does cyanide not react destructively with the proximal iron center at the active site of 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase, an enzyme central to the biosynthesis of ethylene in plants? It has long been postulated that the cyanoformate anion, [NCCO2]–, forms and then decomposes to carbon dioxide and cyanide during this process. We have now isolated and crystallographically characterized this elusive anion as its tetraphenylphosphonium salt. Theoretical calculations show that cyanoformate has a very weak C–C bond and that it is thermodynamically stable only in low dielectric media. Solution stability studies have substantiated the latter result. We propose that cyanoformate shuttles the potentially toxic cyanide away from the low dielectric active site of ACC oxidase before breaking down in the higher dielectric medium of the cell.

scholarly journals Size, Shape, and Material Effects in Ferroelectric Octahedral Nanoparticles

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Daopei Zhu ◽  
Haocheng Yan ◽  
Siyuan Tian ◽  
Zhangli Wang
Keyword(s):  
Dielectric Permittivity ◽  
Dielectric Medium ◽  
Material Parameters ◽  
Low Dielectric ◽  
High Dielectric Permittivity ◽  
The Matrix ◽  
Potential Applications ◽  
Critical Particle Size ◽  
High Dielectric ◽  
Low Permittivity

Composite materials composed of multiferroelectric nanoparticles in dielectric matrixes have attracted enormous attention for their potential applications in developing future functional devices. However, the functionalities of ferroelectric nanoparticles depend on shapes, sizes, and materials. In this paper, a time-dependent Landau-Ginzburg method has been used and combined with a method as the coupled-physics finite-element-method-based simulations are used to illustrate the polarization behavior in isolated BaTiO3 or PbTiO3 octahedral nanoparticles embedded in a dielectric medium, like SrTiO3 (ST, high dielectric permittivity) and amorphous silica (a-SiO2, low dielectric permittivity). The equilibrium polarization topology of the octahedral nanoparticle is strongly affected by the choice of inclusion and the size of matrix materials. Also, there are three equilibrium polarization patterns, i.e., monodomain, vortex-like, and multidomain, because of the various sizes and material parameters combination. There is a critical particle size below which ferroelectricity vanishes in our calculations. This size of the PbTiO3 octahedral nanoparticle is 2.5 and 3.6 nm for high- and low-permittivity matrix materials, respectively. However, this size of the BaTiO3 octahedral nanoparticle is 3.6 nm regardless of the matrix materials.

Modification of Low ĸ Materials for ULSI Multilevel Interconnects by Ion Implantation

2002 ◽  
Vol 716 ◽  
Author(s):  
Alok Nandini ◽  
U. Roy ◽  
A. Mallikarjunan ◽  
A. Kumar ◽  
J. Fortin ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Ion Implantation ◽  
Dielectric Materials ◽  
Dramatic Improvement ◽  
Force Microscopy ◽  
Low Dielectric ◽  
Quantitative Measurements ◽  
Hardness Increase ◽  
Xerogel Films ◽  
Ion Species

AbstractThin films of low dielectric constant (κ) materials such as Xerogel (ĸ=1.76) and SilkTM (ĸ=2.65) were implanted with argon, neon, nitrogen, carbon and helium with 2 x 1015 cm -2 and 1 x 1016 cm -2 dose at energies varying from 50 to 150 keV at room temperature. In this work we discuss the improvement of hardness as well as elasticity of low ĸ dielectric materials by ion implantation. Ultrasonic Force Microscopy (UFM) [6] and Nano indentation technique [5] have been used for qualitative and quantitative measurements respectively. The hardness increased with increasing ion energy and dose of implantation. For a given energy and dose, the hardness improvement varied with ion species. Dramatic improvement of hardness is seen for multi-dose implantation. Among all the implanted ion species (Helium, Carbon, Nitrogen, Neon and Argon), Argon implantation resulted in 5x hardness increase in Xerogel films, sacrificing only a slight increase (∼ 15%) in dielectric constant.

Low-Dielectric-Constant Materials for ULSI Interlayer-Dielectric Applications

MRS Bulletin ◽  
1997 ◽  
Vol 22 (10) ◽  
pp. 19-27 ◽  
Author(s):  
Wei William Lee ◽  
Paul S. Ho
Keyword(s):  
Packing Density ◽  
Propagation Delay ◽  
Single Chip ◽  
Crosstalk Noise ◽  
Metal Line ◽  
Total Delay ◽  
Interlayer Dielectric ◽  
Low Dielectric ◽  
Interconnect Delay ◽  
Interconnect Technology

Continuing improvement of microprocessor performance historically involves a decrease in the device size. This allows greater device speed, an increase in device packing density, and an increase in the number of functions that can reside on a single chip. However higher packing density requires a much larger increase in the number of interconnects. This has led to an increase in the number of wiring levels and a reduction in the wiring pitch (sum of the metal line width and the spacing between the metal lines) to increase the wiring density. The problem with this approach is that—as device dimensions shrink to less than 0.25 μm (transistor gate length)—propagation delay, crosstalk noise, and power dissipation due to resistance-capacitance (RC) coupling become significant due to increased wiring capacitance, especially interline capacitance between the metal lines on the same metal level. The smaller line dimensions increase the resistivity (R) of the metal lines, and the narrower interline spacing increases the capacitance (C) between the lines. Thus although the speed of the device will increase as the feature size decreases, the interconnect delay becomes the major fraction of the total delay and limits improvement in device performance.To address these problems, new materials for use as metal lines and interlayer dielectrics (ILD) as well as alternative architectures have been proposed to replace the current Al(Cu) and SiO2 interconnect technology.

Accurate and Nonparametric Imaging Algorithm for Targets Buried in Dielectric Medium for UWB Radars

2012 ◽  
Vol E95.C (8) ◽  
pp. 1389-1398 ◽  
Author(s):  
Ken AKUNE ◽  
Shouhei KIDERA ◽  
Tetsuo KIRIMOTO
Keyword(s):  
Dielectric Medium ◽  
Imaging Algorithm

Oscillations in a Resonator Filled With a Time-Varying Dielectric Medium

1998 ◽  
Vol 52 (6) ◽  
pp. 36-45 ◽  
Author(s):  
Oleg Aleksandrovich Tretyakov ◽  
S. V. Chumachenko
Keyword(s):  
Dielectric Medium ◽  
Time Varying
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