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Journal articles on the topic 'Electrostic barriers'

Author: Grafiati

Published: 4 June 2021

Last updated: 14 February 2022

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1

Lee, Myungjin, Chen Bai, Mikolaj Feliks, Raphael Alhadeff, and Arieh Warshel. "On the control of the proton current in the voltage-gated proton channel Hv1." Proceedings of the National Academy of Sciences 115, no. 41 (September 25, 2018): 10321–26. http://dx.doi.org/10.1073/pnas.1809766115.

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The nature of the action of voltage-activated proton transport proteins is a conundrum of great current interest. Here we approach this issue by exploring the action of Hv1, a voltage-gated proton channel found in different cells in humans and other organisms. Our study focuses on evaluating the free energy of transporting a proton through the channel, as well as the effect of the proton transfer through D112, in both the closed and open channel conformations. It is found that D112 allows a transported proton to bypass the electrostatic barrier of the open channel, while not being able to help in passing the barrier in the closed form. This reflects the change in position of the gating arginine residues relative to D112, upon voltage activation. Significantly, the effect of D112 accounts for the observed trend in selectivity by overcoming the electrostatic barrier at its highest point. Thus, the calculations provide a structure/function correlation for the Hv1 system. The present work also clarifies that the action of Hv1 is not controlled by a Grotthuss mechanism but, as is always the case, by the protein electrostatic potential at the rate-limiting barriers.

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2

Schaefer, Ted, Craig S. Takeuchi, Guy M. Bernard, and Frank E. Hruska. "Theoretical and experimental barriers to internal rotation in 2,6-difluorobenzaldehyde and 2,4,6-trifluorobenzaldehyde. Relatively low barriers." Canadian Journal of Chemistry 73, no. 1 (January 1, 1995): 106–12. http://dx.doi.org/10.1139/v95-016.

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The free energies of activation at 110 K for rotation about the exocyclic C—C bonds in 2,6-difluorobenzaldehyde and 2,4,6-trifluorobenzaldehyde, in dimethyl ether solutions, are 18.8 ± 0.5 and 20.0 ± 0.5 kJ mol−1, respectively, as determined from 19F{1H} dynamic nuclear magnetic resonance measurements. For the parent compound ΔG≠ is 32.2 kJ mol−1 in the same solvent. These free energy barriers, the lowest available for benzaldehyde derivatives, are likely a result of steric and electrostatic repulsions between the C+—O− and C+—F− bonds. Computations of the spectroscopic barrier in the 2,6-difluoro compound at various levels of molecular orbital theory imply that the barrier is predominantly twofold, with a fourfold component of opposite sign, whose magnitude is about 10% of the twofold component. A correlation-gradient computation, MP2/6-31G*, finds a barrier height of 18.6 kJ mol−1 for this compound, lower by 3.0 kJ mol−1 than found with the 6-31G* basis and 2.9 kJ mol−1 with 6-31G**. Similar computations are compared for the parent compound and the 4-fluoro, 2,4,6-trifluoro, and 3,5-difluoro derivatives. Linear relationships exist between the computed spectroscopic barriers (ΔE values at absolute zero for the free molecules) and the free energy barriers for benzaldehyde and the four fluoro derivatives; the theoretical barriers utilize 6-31G** and correlation-gradient MP2/6-31G* procedures. For the 2,6-difluoro derivative, the computed frequencies of the torsional motions about the exocyclic C—C bond yield spectroscopic twofold barriers. These barriers are much lower than the computed energy differences between the planar and perpendicular conformers, perhaps because the negative fourfold components flatten the potential at its minimum. A rough estimate of the relationship between ΔG≠ and ΔE0 for the 2,6-difluorobenzaldehyde suggests that the solvent increases the internal barrier by only about 3 kJ mol−1. By way of contrast, the AM1 barriers, scaled by a factor of 1.9 (as previously recommended) range from 17.3 to 22.6 kJ mol−1, the ΔG≠ values from 18.8(5) to 34.4 kJ mol−1, and the MP2/6-31G* (correlation-gradient) barriers span 18.6 to 36.8 kJ mol−1 for benzaldehyde and the four fluorine derivatives. It seems likely that the internal barrier in benzaldehyde is considerably larger than that modeled on torsional frequencies. Keywords: Free energies of activation, internal rotational barriers in 2,6-difluoro- and 2,4,6-trifluorobenzaldehyde; molecular orbital computations, internal rotational barriers in 2,6-difluoro- and 2,4,6-trifluorobenzaldehyde; correlation gradient computations on internal barriers in benzaldehyde and four of its fluorine derivatives.

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3

Li, Hao, Yan-Li Zhao, Albert C. Fahrenbach, Soo-Young Kim, Walter F. Paxton, and J. Fraser Stoddart. "Degenerate [2]rotaxanes with electrostatic barriers." Organic & Biomolecular Chemistry 9, no. 7 (2011): 2240. http://dx.doi.org/10.1039/c0ob00937g.

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4

Hmadeh, Mohamad, Albert C. Fahrenbach, Subhadeep Basu, Ali Trabolsi, Diego Benítez, Hao Li, Anne‐Marie Albrecht‐Gary, Mourad Elhabiri, and J. Fraser Stoddart. "Electrostatic Barriers in Rotaxanes and Pseudorotaxanes." Chemistry – A European Journal 17, no. 22 (April 15, 2011): 6076–87. http://dx.doi.org/10.1002/chem.201002933.

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5

Zhou, Xuechen, Zhangxin Wang, Razi Epsztein, Cheng Zhan, Wenlu Li, John D. Fortner, Tuan Anh Pham, Jae-Hong Kim, and Menachem Elimelech. "Intrapore energy barriers govern ion transport and selectivity of desalination membranes." Science Advances 6, no. 48 (November 2020): eabd9045. http://dx.doi.org/10.1126/sciadv.abd9045.

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State-of-the-art desalination membranes exhibit high water-salt selectivity, but their ability to discriminate between ions is limited. Elucidating the fundamental mechanisms underlying ion transport and selectivity in subnanometer pores is therefore imperative for the development of ion-selective membranes. Here, we compare the overall energy barrier for salt transport and energy barriers for individual ion transport, showing that cations and anions traverse the membrane pore in an independent manner. Supported by density functional theory simulations, we demonstrate that electrostatic interactions between permeating counterion and fixed charges on the membrane substantially hinder intrapore diffusion. Furthermore, using quartz crystal microbalance, we break down the contributions of partitioning at the pore mouth and intrapore diffusion to the overall energy barrier for salt transport. Overall, our results indicate that intrapore diffusion governs salt transport through subnanometer pores due to ion-pore wall interactions, providing the scientific base for the design of membranes with high ion-ion selectivity.

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6

COMA, V., I. SEBTI, P. PARDON, A. DESCHAMPS, and F. H. PICHAVANT. "Antimicrobial Edible Packaging Based on Cellulosic Ethers, Fatty Acids, and Nisin Incorporation To Inhibit Listeria innocua and Staphylococcus aureus." Journal of Food Protection 64, no. 4 (April 1, 2001): 470–75. http://dx.doi.org/10.4315/0362-028x-64.4.470.

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Edible cellulosic films made with hydroxypropylmethylcellulose (HPMC) have proven to be inadequate moisture barriers. To improve its water vapor barrier properties, different hydrophobic compounds were incorporated into the HPMC matrix. Some fatty acids and derivatives were included into the film-forming solution prior to film formation. Stearic acid was chosen because of its high capacity to reduce significantly the water vapor transmission rate. Antimicrobial activity of edible HPMC film was obtained by the incorporation of nisin into the film-forming solution. Nisin is an antimicrobial peptide effective against gram-positive bacteria. The inhibitory activity of this bacteriocin was tested for inhibition of Listeria innocua and Staphylococcus aureus. The use of stearic acid was observed to reduce the inhibitory activity of active HPMC film against both selected strains. This phenomenon may be explained by electrostatic interactions between the cationic nisin and the anionic stearic acid. Further studies showed that antimicrobial activity of film varied with the nature of the hydrophobic compound incorporated, in decreasing order: film without lipid, methylstearate film, and stearic acid film. This corroborated the idea of electrostatic interactions.

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7

AGRAWAL (GARG), NEETU, SANKALPA GHOSH, and MANISH SHARMA. "ELECTRON OPTICS WITH DIRAC FERMIONS: ELECTRON TRANSPORT IN MONOLAYER AND BILAYER GRAPHENE THROUGH MAGNETIC BARRIER AND THEIR SUPERLATTICES." International Journal of Modern Physics B 27, no. 10 (April 20, 2013): 1341003. http://dx.doi.org/10.1142/s0217979213410038.

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In this review article we discuss the recent progress in studying ballistic transport for charge carriers in graphene through highly inhomogeneous magnetic field known as magnetic barrier in combination with gate voltage induced electrostatic potential. Starting with cases for a single or double magnetic barrier we also review the progress in understanding electron transport through the superlattices created out of such electromagnetic potential barriers and discuss the possibility of experimental realization of such systems. The emphasis is particularly on the analogy of such transport with propagation of light wave through medium with alternating dielectric constant. In that direction we discuss electron analogue of optical phenomena like Fabry–Perot resonances, negative refraction, Goos–Hänchen effect, beam collimation in such systems and explain how such analogy is going to be useful for device generation. The resulting modification of band structure of Dirac fermions, the emergence of additional Dirac points was also discussed accompanied by brief section on the interconvertibility of electric and magnetic field for relativistic Dirac fermions. We also discuss the effect of such electromagnetic potential barrier on bilayer graphene (BLG) in a similar framework.

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8

Chung, Suk, Shane R. Johnson, Ding Ding, Yong-Hang Zhang, David J. Smith, and Martha R. McCartney. "Quantitative Analysis of Dopant Distribution and Activation Across p-n Junctions in AlGaAs/GaAs Light-Emitting Diodes Using Off-Axis Electron Holography." IEEE Transactions on Electron Devices 56, no. 10 (September 2009): 1919–23. http://dx.doi.org/10.1109/ted.2009.2025914.

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Off-axis electron holography has been used to measure the electrostatic potential profile across the p-n junction of an AlGaAs/GaAs light-emitting diode with linearly graded triangular AlGaAs barriers. Simulations of the junction profile showed small discrepancies with experiment when the nominal dopant concentrations of Si and Be impurities were used. Revised simulations reproduced the measurements reasonably using reduced dopant levels that reflected the efficiency of dopant activation. Band-edge diagrams simulated with the nominal and revised dopant concentrations were also compared in terms of the effect that activation efficiency had on the AlGaAs barrier shape and carrier transport. It is concluded that electron holography measurements combined with modeling offer device designers and growers a helpful tool for analyzing and confirming doping profiles in complex heterostructures.

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9

Choubabi, El Bouâzzaoui, Ahmed Jellal, Abdellatif Kamal, and Hocine Bahlouli. "Tunneling through Double Electrostatic Barriers in Strained Graphene." physica status solidi (b) 257, no. 3 (November 28, 2019): 1900414. http://dx.doi.org/10.1002/pssb.201900414.

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10

Kane, C. L., and E. J. Mele. "Dielectric control of electrostatic barriers for molecular electronics." Applied Physics Letters 78, no. 1 (January 2001): 114–16. http://dx.doi.org/10.1063/1.1336162.

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11

Belkouch, S., L. Paquin, A. Deneuville, and E. Gheeraert. "Caractérisation physicochimique et électronique de la structure Pt–a-Si: H–c-Si(n)." Canadian Journal of Physics 69, no. 3-4 (March 1, 1991): 357–60. http://dx.doi.org/10.1139/p91-060.

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Infrared absorption spectra, and electrical measurements I(V, T) and C(V) at 100 Hz of the Pt–a-Si:H–c-Si structure are presented. The thickness, d, of the hydrogenated amorphous silicium, a-Si:H, varies between 4800 and 180 Å(1 Å = 10−10 m). Infrared absorption measurements on a-Si:H show that with the decrease in d there is an increase in the number of defects and the hydrogen concentration on Si-H sites. The electrical results I(V, T) show a Schottky-like structure whose ideality factor increases with decreasing T, but remains limited even for small values of d (1.4 at 300 K for d = 180 Å). Two potential barriers are also deduced: at high temperature [Formula: see text] and is independent of d. This barrier is attributed to the Pt–a-Si:H interface. At low temperature, [Formula: see text] increases from 0.23 to 0.5 eV as d decreases from 2400 to 180 Å. This barrier is attributed to the a-Si = H–c-Si, interface, the transport in a-Si:H taking place by tunnelling between localized states. The C(V) measurements allow the separation between the c-Si and the a-Si:H responses. Above 100 kHz, there is no response from a-Si:H, which behaves then as a dielectric. The electrostatic potential drop in c-Si is deduced as a function of the applied voltage V for each value of d. A positive electrostatic potential is found when V = 0 for d ≤ 500 Å.[Journal translation]

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12

Торхов, Н. А. "Влияние электростатического поля периферии на вентильный фотоэффект в контактах металл-полупроводник с барьером Шоттки." Физика и техника полупроводников 52, no. 10 (2018): 1150. http://dx.doi.org/10.21883/ftp.2018.10.46455.8620.

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AbstractStudies of an electrostatic system of flat metal–semiconductor contacts with a Schottky barrier reveals a nontrivial dependence of their current and voltage photosensitivity (the photovoltaic effect) on the contact shape. The specific features of using the photovoltaic effect in such contacts are determined, to a great extent, by the built-in periphery electrostatic field with an absolute value that depends on the contact perimeter and area. Thus, to increase the efficiency of light-to-electrical energy conversion by Schottky contacts, it is necessary to use optimization techniques based on the concepts of the proposed physical model of an electrostatic system of flat Schottky contacts with regard to periphery electrostatic fields. The “hot electron resonance” effect, which enhances the external quantum efficiency of photodiodes with a Schottky barrier, can be explained by enhancement of the field emission of electrons by the periphery electrostatic field.

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13

Rossella, Francesco, Daniele Ercolani, Lucia Sorba, Fabio Beltram, and Stefano Roddaro. "Electrostatic spin control in multi-barrier nanowires." Journal of Physics D: Applied Physics 47, no. 39 (September 11, 2014): 394015. http://dx.doi.org/10.1088/0022-3727/47/39/394015.

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14

Wang, Zhi-Tao, Yang-Gang Wang, Rentao Mu, Yeohoon Yoon, Arjun Dahal, Gregory K. Schenter, Vassiliki-Alexandra Glezakou, Roger Rousseau, Igor Lyubinetsky, and Zdenek Dohnálek. "Probing equilibrium of molecular and deprotonated water on TiO2(110)." Proceedings of the National Academy of Sciences 114, no. 8 (February 6, 2017): 1801–5. http://dx.doi.org/10.1073/pnas.1613756114.

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Understanding adsorbed water and its dissociation to surface hydroxyls on oxide surfaces is key to unraveling many physical and chemical processes, yet the barrier for its deprotonation has never been measured. In this study, we present direct evidence for water dissociation equilibrium on rutile-TiO2(110) by combining supersonic molecular beam, scanning tunneling microscopy (STM), and ab initio molecular dynamics. We measure the deprotonation/protonation barriers of 0.36 eV and find that molecularly bound water is preferred over the surface-bound hydroxyls by only 0.035 eV. We demonstrate that long-range electrostatic fields emanating from the oxide lead to steering and reorientation of the molecules approaching the surface, activating the O–H bonds and inducing deprotonation. The developed methodology for studying metastable reaction intermediates prepared with a high-energy molecular beam in the STM can be readily extended to other systems to clarify a wide range of important bond activation processes.

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15

Dugyala, Venkateshwar Rao, Jyothi Sri Muthukuru, Ethayaraja Mani, and Madivala G. Basavaraj. "Role of electrostatic interactions in the adsorption kinetics of nanoparticles at fluid–fluid interfaces." Physical Chemistry Chemical Physics 18, no. 7 (2016): 5499–508. http://dx.doi.org/10.1039/c5cp05959c.

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16

Wu, Haichao, Raphaël Sarfati, Dapeng Wang, and Daniel K. Schwartz. "Electrostatic Barriers to Nanoparticle Accessibility of a Porous Matrix." Journal of the American Chemical Society 142, no. 10 (February 20, 2020): 4696–704. http://dx.doi.org/10.1021/jacs.9b12096.

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17

Sadlej-Sosnowska, Nina. "Energy Barriers to Internal Rotation: Hyperconjugation and Electrostatic Description." Journal of Physical Chemistry A 107, no. 41 (October 2003): 8671–76. http://dx.doi.org/10.1021/jp030152r.

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18

Zettergren, H., J. Jensen, H. T. Schmidt, and H. Cederquist. "Electrostatic model calculations of fission barriers for fullerene ions." European Physical Journal D - Atomic, Molecular and Optical Physics 29, no. 1 (April 1, 2004): 63–68. http://dx.doi.org/10.1140/epjd/e2004-00006-6.

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19

Bennett, Kaila M., Sharon L. Walker, and David D. Lo. "Epithelial Microvilli Establish an Electrostatic Barrier to Microbial Adhesion." Infection and Immunity 82, no. 7 (April 28, 2014): 2860–71. http://dx.doi.org/10.1128/iai.01681-14.

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ABSTRACTMicrovilli are membrane extensions on the apical surface of polarized epithelia, such as intestinal enterocytes and tubule and duct epithelia. One notable exception in mucosal epithelia is M cells, which are specialized for capturing luminal microbial particles; M cells display a unique apical membrane lacking microvilli. Based on studies of M cell uptake under different ionic conditions, we hypothesized that microvilli may augment the mucosal barrier by providing an increased surface charge density from the increased membrane surface and associated glycoproteins. Thus, electrostatic charges may repel microbes from epithelial cells bearing microvilli, while M cells are more susceptible to microbial adhesion. To test the role of microvilli in bacterial adhesion and uptake, we developed polarized intestinal epithelial cells with reduced microvilli (“microvillus-minus,” or MVM) but retaining normal tight junctions. When tested for interactions with microbial particles in suspension, MVM cells showed greatly enhanced adhesion and uptake of particles compared to microvillus-positive cells. This preference showed a linear relationship to bacterial surface charge, suggesting that microvilli resist binding of microbes by using electrostatic repulsion. Moreover, this predicts that pathogen modification of electrostatic forces may contribute directly to virulence. Accordingly, the effacement effector protein Tir from enterohemorrhagicEscherichia coliO157:H7 expressed in epithelial cells induced a loss of microvilli with consequent enhanced microbial binding. These results provide a new context for microvillus function in the host-pathogen relationship, based on electrostatic interactions.

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20

Akimkin, Vitaly. "Retention of Small Charged Dust in Planet Forming Disks." Proceedings of the International Astronomical Union 14, S345 (August 2018): 283–84. http://dx.doi.org/10.1017/s1743921318008608.

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AbstractDust evolution in disks around young stars is a key ingredient for the global disk evolution and accompanying planet formation. The mutual sticking of initially small grains is not straightforward and can be hampered by several processes. This includes dust grain bouncing, fragmentation, electrostatic repulsion and fast drift to the central star. In this study we aim at theoretical modeling of the dust coagulation coupled with the dust charging and disk ionization calculations. We show that the electrostatic barrier is a strong restraining factor to the coagulation of micron-size dust. While the sustained turbulence helps to overcome the electrostatic barrier, dust fluffiness limits this opportunity. Coulomb repulsion may keep a significant fraction of m dust in large regions of protoplanetary disks.

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21

Yateem, Ali Hussain. "Rotational Barrier and Conjugation: Theoretical Study of Resonance Stabilization of Various Substituents for the Donors NH₂ and OCH₃ in Substituted 1,3-Butadienes." Indonesian Journal of Chemistry 19, no. 4 (August 13, 2019): 1055. http://dx.doi.org/10.22146/ijc.42850.

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The barrier to internal rotation around the central C2–C3 single bond of a series of (1E)-monosubstituted 1,3-butadienes and (1E,3E)-1-Y-4-X-disubstituted butadienes, with Y=NH2 or OCH3 and X=NO2, CHO, COOH, CN, CF3, Cl or F, were studied at the density functional w B97X-D/6-31G∗∗ level. The effect of substituents on π-conjugation in disubstituted 1,3-butadienes was studied by correlating the calculated internal rotational barriers with the difference in structural, atomic and molecular properties between the transition state TS and the s-trans conformers. The calculated differences in lengths of C–C, C–NH2 and C–OCH3 single bonds, N-H-N, and C-O-CH3 angles, NH2 out-of-plane angle, natural charges on amino nitrogen and methoxy oxygen, and the maximum electrostatic potential on amino hydrogens, were found to correlate strongly with the rotational barriers. The conjugative interaction was strongly stabilized in the case of strong π-electron acceptors such as NO2 or CHO and is slightly or negligibly affected with Cl and F groups. The resonance stabilization with the remaining acceptors decreases in the order COOH > CN > CF3. Acceptors X maintain their relative order of stabilization for the two donors, and NH2 is more stabilizing. Dominant resonance structures are suggested for highly and negligibly conjugated systems.

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22

Zhou, Benliang, Benhu Zhou, and Guanghui Zhou. "Electronic tunneling through a potential barrier on the surface of a topological insulator." Modern Physics Letters B 30, no. 35 (December 20, 2016): 1650416. http://dx.doi.org/10.1142/s0217984916504169.

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We investigate the tunneling transport for electrons on the surface of a topological insulator (TI) through an electrostatic potential barrier. By using the Dirac equation with the continuity conditions for all segments of wave functions at the interfaces between regions inside and outside the barrier, we calculate analytically the transmission probability and conductance for the system. It is demonstrated that, the Klein paradox can also been observed in the system same as in graphene system. Interestingly, the conductance reaches the minimum value when the incident electron energy is equal to the barrier strength. Moreover, with increasing barrier width, the conductance turns up some tunneling oscillation peaks, and larger barrier strength can cause lower conductance, shorter period but larger oscillation amplitude. The oscillation amplitude decreases as the barrier width increases, which is similar as that of the system consisting of the compressive uniaxial strain applied on a TI, but somewhat different from that of graphene system where the oscillation amplitude is a constant. The findings here imply that an electrostatic barrier can greatly influence the electron tunneling transport of the system, and may provide a new way to realize directional filtering of electrons.

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23

McDevitt, C. J., and P. H. Diamond. "Low-q resonances, transport barriers, and secondary electrostatic convective cells." Physics of Plasmas 14, no. 11 (November 2007): 112306. http://dx.doi.org/10.1063/1.2806327.

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24

Cooper, K. E., P. Y. Gates, and R. S. Eisenberg. "Surmounting barriers in ionic channels." Quarterly Reviews of Biophysics 21, no. 3 (August 1988): 331–64. http://dx.doi.org/10.1017/s0033583500004480.

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Biological cells are defined by the membrane that shields their vital molecules from the environment. The lipid bilayer of the membrane is an effective dielectric shield (Parsegian, 1969; Andersen, 1978; Honig et al. 1986), preventing penetration by charged molecules: the lipid presents a large electrostatic energy barrier because it cannot neutralize the charge of solute molecules nearly as well as water. This energy barrier inhibits the permeation of solutes with local charge, even metabolites. Of course, metabolites do enter cells, and so physiologists have suspected (for a very long time, Hille, 1984, ch. 8) that the membrane shield is pierced by aqueous channels, through which solutes diffuse (with their local charge substantially neutralized) as they cross the membrane. These aqueous pores now have molecular reality (e.g. Noda et al. 1984; Miller, 1986). Each is formed by a specialized protein, integral to membranes, perhaps shaped like a thick-walled pipe, called ionic channels. Channels control the movement of many important molecules in and out of cells by the ‘gating’ mechanism that controls their opening and closing and by the selective properties of their open channel.

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25

Cao, Wei, Chen Gao, Yi-Quan Zhang, Dongdong Qi, Tao Liu, Kang Wang, Chunying Duan, Song Gao, and Jianzhuang Jiang. "Rational enhancement of the energy barrier of bis(tetrapyrrole) dysprosium SMMs via replacing atom of porphyrin core." Chemical Science 6, no. 10 (2015): 5947–54. http://dx.doi.org/10.1039/c5sc02314a.

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26

Romei, Matthew G., Chi-Yun Lin, Irimpan I. Mathews, and Steven G. Boxer. "Electrostatic control of photoisomerization pathways in proteins." Science 367, no. 6473 (January 2, 2020): 76–79. http://dx.doi.org/10.1126/science.aax1898.

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Rotation around a specific bond after photoexcitation is central to vision and emerging opportunities in optogenetics, super-resolution microscopy, and photoactive molecular devices. Competing roles for steric and electrostatic effects that govern bond-specific photoisomerization have been widely discussed, the latter originating from chromophore charge transfer upon excitation. We systematically altered the electrostatic properties of the green fluorescent protein chromophore in a photoswitchable variant, Dronpa2, using amber suppression to introduce electron-donating and electron-withdrawing groups to the phenolate ring. Through analysis of the absorption (color), fluorescence quantum yield, and energy barriers to ground- and excited-state isomerization, we evaluate the contributions of sterics and electrostatics quantitatively and demonstrate how electrostatic effects bias the pathway of chromophore photoisomerization, leading to a generalized framework to guide protein design.

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27

Coondoo, Indrani, Neeraj Panwar, Reddithota Vidyasagar, and Andrei L. Kholkin. "Defect chemistry and relaxation processes: effect of an amphoteric substituent in lead-free BCZT ceramics." Physical Chemistry Chemical Physics 18, no. 45 (2016): 31184–201. http://dx.doi.org/10.1039/c6cp06244j.

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28

Cherstvy, A. G. "Electrostatic Screening and Energy Barriers of Ions in Low-dielectric Membranes." Journal of Physical Chemistry B 110, no. 29 (July 2006): 14503–6. http://dx.doi.org/10.1021/jp061745f.

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29

Dakhlaoui, Hassen, Walid Belhadj, and Bryan M. Wong. "Quantum tunneling mechanisms in monolayer graphene modulated by multiple electrostatic barriers." Results in Physics 26 (July 2021): 104403. http://dx.doi.org/10.1016/j.rinp.2021.104403.

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30

Heide, C. "Current through a combined magnetostatic and electrostatic barrier system." Physical Review B 60, no. 4 (July 15, 1999): 2571–78. http://dx.doi.org/10.1103/physrevb.60.2571.

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31

Alig, Tim F., Heidi E. Warriner, Lily Lee, and Joseph A. Zasadzinski. "Electrostatic Barrier to Recovery of Dipalmitoylphosphatidylglycerol Monolayers after Collapse." Biophysical Journal 86, no. 2 (February 2004): 897–904. http://dx.doi.org/10.1016/s0006-3495(04)74165-x.

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32

Young, David L., and Richard S. Crandall. "An electrostatic barrier to trap filling in CuIn1−xGaxSe2." Applied Physics Letters 83, no. 12 (September 22, 2003): 2363–65. http://dx.doi.org/10.1063/1.1613034.

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33

Hakala, Reino W., and Alfred E. Fields. "Electrostatic contribution to the internal rotational barrier in ethane." International Journal of Quantum Chemistry 1, S1 (June 18, 2009): 197–98. http://dx.doi.org/10.1002/qua.560010623.

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34

Singh, Amandeep, Mamta Khosla, and Balwinder Raj. "Circuit Compatible Model for Electrostatic Doped Schottky Barrier CNTFET." Journal of Electronic Materials 45, no. 10 (June 30, 2016): 5381–90. http://dx.doi.org/10.1007/s11664-016-4743-7.

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35

Breneman, Curt M., and Lawrence W. Weber. "Charge and energy redistribution in sulfonamides undergoing conformational changes. Hybridization as a controlling influence over conformer stability." Canadian Journal of Chemistry 74, no. 6 (June 1, 1996): 1271–82. http://dx.doi.org/10.1139/v96-143.

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The redistribution of charge and electronic kinetic energy was studied during rotation about the S—N bonds of sulfonamide and fluorosulfonamide. The rotational potentials and electronic topological features of both compounds were evaluated at the HF/6-3 1G* level of theory and their electron densities partitioned into atomic contributions using FASTINT, an updated version of the PROAIM program. The results indicate that the stability of each rotamer is strongly dependent upon the hybridization of the sulfonamide nitrogen. The hybridization of the nitrogen was determined by examination of the positions and magnitudes of the electrostatic and Laplacian minima in the nonbonded region of the sulfonamide nitrogen atom. Independent assessments of hybridization were made using nitrogen pyramidalization altitudes. The rotational barriers in these compounds were found to arise mainly from energetic penalties resulting from adding electrons to already electron-rich sulfonyl oxygens while removing electron density from other more electronegative atoms. The fluorine-substituted analogue provided an example in which the sulfur and oxygen atoms were much less electron rich, causing an enhancement of the nitrogen rehybridization effects. The extent of covalent bonding between pertinent pairs of atoms in sulfonamide and fluorosulfonamide was assessed throughout the rotational pathway using the BONDER program. In contrast with much existing dogma, all of these findings were consistent with the same general model of charge and energy flow that has been shown to determine the internal rotational barriers in amides. Key words: sulfonamide, electron density analysis, rotational barrier, hybridization, atoms-in-molecules calculations.

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36

Sahu, Subin, and Michael Zwolak. "Diffusion Limitations and Translocation Barriers in Atomically Thin Biomimetic Pores." Entropy 22, no. 11 (November 20, 2020): 1326. http://dx.doi.org/10.3390/e22111326.

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Ionic transport in nano- to sub-nano-scale pores is highly dependent on translocation barriers and potential wells. These features in the free-energy landscape are primarily the result of ion dehydration and electrostatic interactions. For pores in atomically thin membranes, such as graphene, other factors come into play. Ion dynamics both inside and outside the geometric volume of the pore can be critical in determining the transport properties of the channel due to several commensurate length scales, such as the effective membrane thickness, radii of the first and the second hydration layers, pore radius, and Debye length. In particular, for biomimetic pores, such as the graphene crown ether we examine here, there are regimes where transport is highly sensitive to the pore size due to the interplay of dehydration and interaction with pore charge. Picometer changes in the size, e.g., due to a minute strain, can lead to a large change in conductance. Outside of these regimes, the small pore size itself gives a large resistance, even when electrostatic factors and dehydration compensate each other to give a relatively flat—e.g., near barrierless—free energy landscape. The permeability, though, can still be large and ions will translocate rapidly after they arrive within the capture radius of the pore. This, in turn, leads to diffusion and drift effects dominating the conductance. The current thus plateaus and becomes effectively independent of pore-free energy characteristics. Measurement of this effect will give an estimate of the magnitude of kinetically limiting features, and experimentally constrain the local electromechanical conditions.

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37

Farah, Salim F., Robert A. McClelland, Michael R. Peterson, and Imre G. Csizmadia. "Molecular structure and relative proton and electron affinities of isomeric nitroimidazoles." Canadian Journal of Chemistry 67, no. 10 (October 1, 1989): 1666–71. http://dx.doi.org/10.1139/v89-255.

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The isomeric 2-nitro, 4-nitro, and 5-nitroimidazoles have been studied in their planar ground state, C—NO2 rotational transition state, 3-H protonated conjugate acid and radical anion forms, with abinitio computations at the split-valence 3-21G basis set level. The stabilities of the parent compounds follow the order 5-NO2 ~ 4-NO2 > 2-NO2. In solution 4-nitro is more stable than 5-nitro; the calculations suggest that this is a solvation effect, since the 4-nitro isomer has a considerably higher dipole moment. Barriers for nitro group rotation range from 10 to 16 kcal/mol. However, the relative change in dipole moment during the rotation is small, suggesting that dipole moments of nitroimidazoles are determined mainly by inductive effects, with resonance interactions being relatively unimportant. This conclusion is supported by calculations of molecular electrostatic potentials of the planar and rotated forms. Electron affinities follow the order [Formula: see text], closely matching the order of biological effectiveness of nitroimidazole radiosensitizers. This is consistent with suggestions that the "nitro:nitro radical anion" redox cycle is an important determinant of biological activity. Keywords: nitroimidazole, abinitio computation, rotational barrier, proton affinity, electron affinity.

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38

Wu, Haichao, Benjamin Greydanus, and Daniel K. Schwartz. "Mechanisms of transport enhancement for self-propelled nanoswimmers in a porous matrix." Proceedings of the National Academy of Sciences 118, no. 27 (June 28, 2021): e2101807118. http://dx.doi.org/10.1073/pnas.2101807118.

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Micro/nanoswimmers convert diverse energy sources into directional movement, demonstrating significant promise for biomedical and environmental applications, many of which involve complex, tortuous, or crowded environments. Here, we investigated the transport behavior of self-propelled catalytic Janus particles in a complex interconnected porous void space, where the rate-determining step involves the escape from a cavity and translocation through holes to adjacent cavities. Surprisingly, self-propelled nanoswimmers escaped from cavities more than 20× faster than passive (Brownian) particles, despite the fact that the mobility of nanoswimmers was less than 2× greater than that of passive particles in unconfined bulk liquid. Combining experimental measurements, Monte Carlo simulations, and theoretical calculations, we found that the escape of nanoswimmers was enhanced by nuanced secondary effects of self-propulsion which were amplified in confined environments. In particular, active escape was facilitated by anomalously rapid confined short-time mobility, highly efficient surface-mediated searching for holes, and the effective abolition of entropic and/or electrostatic barriers at the exit hole regions by propulsion forces. The latter mechanism converted the escape process from barrier-limited to search-limited. These findings provide general and important insights into micro/nanoswimmer mobility in complex environments.

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Joy, D. C., X. Zhang, A. Mohan, and B. Cunningham. "Electron holography of electrostatic fields." Proceedings, annual meeting, Electron Microscopy Society of America 51 (August 1, 1993): 1094–95. http://dx.doi.org/10.1017/s0424820100151301.

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Electron Holography allows both the amplitude and phase of a transmitted wavefront to be stored and subsequently recovered by a reconstruction of the hologram. Since both magnetic and electric fields change the phase of an electron wave that passes through them electron holography can therefore be used to directly, and quantitatively, image such fields. Significant experimental applications have already been made of this technique to the study of magnetic fields and materials, and electric fields have been studied in ferroelectric materials. Such a technique has particular value when applied to the study of semiconductor devices since these rely for their operation on the electric fields produced internally at P-N junctions or Shottky barriers. Holographic imaging of these fields will make it possible to accurately find the active regions of junctions as well as making it possible to measure the electrostatic fields that are present. Consider a cross-sectioned P-N junction of thickness t placed normal to the beam (figure 1).

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40

Halász, Katalin, Yanin Hosakun, and Levente Csóka. "Reducing Water Vapor Permeability of Poly(lactic acid) Film and Bottle through Layer-by-Layer Deposition of Green-Processed Cellulose Nanocrystals and Chitosan." International Journal of Polymer Science 2015 (2015): 1–6. http://dx.doi.org/10.1155/2015/954290.

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Layer-by-layer electrostatic self-assembly technique was applied to improve the barrier properties of poly(lactic acid) (PLA) films and bottles. The LbL process was carried out by the alternate adsorption of chitosan (CH) (polycation) and cellulose nanocrystals (CNC) produced via ultrasonic treatment. Four bilayers (on each side) of chitosan and cellulose nanocrystals caused 29 and 26% improvement in barrier properties in case of films and bottles, respectively. According to the results the LbL process with CH and CNC offered a transparent “green” barrier coating on PLA substrates.

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41

Elfwing, M., M. Saunders, and E. Olsson. "Electron Holography of Potential Barriers in Zno Varistors." Microscopy and Microanalysis 5, S2 (August 1999): 946–47. http://dx.doi.org/10.1017/s1431927600018055.

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ZnO varistor materials are polycrystalline materials that exhibit strong non-linear current-voltage characteristics. Their non-ohmic behaviour makes them suitable for overvoltage protection devices. It is the interfaces between ZnO grains that are the key to the non-linear behaviour of the varistor materials. Previous work has shown that the local microstructure determines the breakdown voltage of the individual ZnO/ZnO interface [1]. The pre-breakdown conductivity and the non-linearity in the breakdown region, which are both crucial to the performance of the varistor, are also affected by the height and the width of the potential barriers. In the present work, electron holography has been used to investigate the potential barriers in ZnO varistor materials.Electron holograms were recorded at 200kV using a Hitachi HF-2000 field emission gun transmission electron microscope [2]. The electrostatic bi-prism was located near the second image plane. The bi-prism voltage was about 9 V and the fringe spacing in the holograms was about 1 nm.

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42

Zimmermann, Nils E. R., Daniel C. Hannah, Ziqin Rong, Miao Liu, Gerbrand Ceder, Maciej Haranczyk, and Kristin A. Persson. "Electrostatic Estimation of Intercalant Jump-Diffusion Barriers Using Finite-Size Ion Models." Journal of Physical Chemistry Letters 9, no. 3 (January 22, 2018): 628–34. http://dx.doi.org/10.1021/acs.jpclett.7b03199.

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43

Buyukdagli, Sahin, and T. Ala-Nissila. "Electrostatic energy barriers from dielectric membranes upon approach of translocating DNA molecules." Journal of Chemical Physics 144, no. 8 (February 28, 2016): 084902. http://dx.doi.org/10.1063/1.4942177.

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44

Liu, Shubin, Hao Hu, and Lee G. Pedersen. "Steric, Quantum, and Electrostatic Effects on SN2 Reaction Barriers in Gas Phase." Journal of Physical Chemistry A 114, no. 18 (May 13, 2010): 5913–18. http://dx.doi.org/10.1021/jp101329f.

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45

Biswas, R., and C. Sinha. "Photon induced tunneling of electron through a graphene electrostatic barrier." Journal of Applied Physics 114, no. 18 (November 14, 2013): 183706. http://dx.doi.org/10.1063/1.4829446.

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46

McCreery, Richard L. "Effects of electronic coupling and electrostatic potential on charge transport in carbon-based molecular electronic junctions." Beilstein Journal of Nanotechnology 7 (January 11, 2016): 32–46. http://dx.doi.org/10.3762/bjnano.7.4.

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Molecular junctions consisting of 2–20 nm thick layers of organic oligomers oriented between a conducting carbon substrate and a carbon/gold top contact have proven to be reproducible and reliable, and will soon enter commercial production in audio processing circuits. The covalent, conjugated bond between one or both sp2-hybridized carbon contacts and an aromatic molecular layer is distinct from the more common metal/molecule or silicon/molecule structures in many reported molecular junctions. Theoretical observations based on density functional theory are presented here, which model carbon-based molecular junctions as single molecules and oligomers between fragments of graphene. Electronic coupling between the molecules and the contacts is demonstrated by the formation of hybrid orbitals in the model structure, which have significant electron density on both the graphene and the molecule. The energies of such hybrid orbitals correlate with tunneling barriers determined experimentally, and electronic coupling between the two graphene fragments in the model correlates with experimentally observed attenuation of transport with molecular layer thickness. Electronic coupling is affected significantly by the dihedral angle between the planes of the graphene and the molecular π-systems, but is absent only when the two planes are orthogonal. Coupling also results in partial charge transfer between the graphene contacts and the molecular layer, which results in a shift in electrostatic potential which affects the observed tunneling barrier. Although the degree of partial charge transfer is difficult to calculate accurately, it does provide a basis for the “vacuum level shift” observed in many experiments, including transport and ultraviolet photoelectron spectroscopy of molecular layers on conductors.

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47

Shi, Yun Bo, Rui Rong Wang, Kang Du, and Jun Liu. "Research on Micromachined Gyroscope with Electrostatic Drive and Meso-Piezoresistive Detection." Advanced Materials Research 154-155 (October 2010): 119–23. http://dx.doi.org/10.4028/www.scientific.net/amr.154-155.119.

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In this paper, the structure design and operating principle is introduced to micromachined gyroscope with electrostatic drive and piezoresistive detection. In the paper, the piezoresistive effect of multi-barrier nano-film is used as detection method, which achieves high piezoresistive sensitivity compared with Silicon piezoresistive device. The gyroscope structure and multi-barrier nano-film device is fabricated by using heteroepitaxy GaAs film on Si substrate which implements the process compatible. The natural frequencies of gyroscope are determined from the modal analysis.

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Raevsky, O. A., D. E. Polianczyk, and O. E. Raevskaja. "Binary classification of blood-brain barrier penetration by the logistic regression method." Biomedical Chemistry: Research and Methods 1, no. 3 (2018): e00065. http://dx.doi.org/10.18097/bmcrm00065.

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Stable classification predictive models of 83 drugs with different blood-brain barrier penetration capacity have been constructed by the logistic regression method using physicochemical descriptors characterizing steric, electrostatic interactions and hydrogen bond energy. The models are balanced, with the prediction level of 75-80%.

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Zuo, Wan Sheng, Yin Xi Niu, Liu Yang, Xiu Zhen Chi, Jin Jin Liu, and Xiao Hong Zhang. "Inserting a AlN Electron Blocking Layer for InGaN/GaN Blue Light-Emitting Diodes." Materials Science Forum 1014 (November 2020): 126–30. http://dx.doi.org/10.4028/www.scientific.net/msf.1014.126.

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In this study, the advantages of the AlN electron blocking layer (EBL) for InGaN/GaN blue light-emitting diodes (LEDs) were investigated. The LEDs with the AlN EBL exhibited better optical performance over a wide range of carrier concentration due to the suppression of electron overflow. Furthermore, the AlN EBL with a thicker last barrier layer was investigated. The thicker last barrier layer was used to enhance Electrostatic Discharge (ESD) characteristic by the better current spreading effect.

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BARBO, F., M. BERTOLO, A. BIANCO, G. CAUTERO, S. FONTANA, T. K. JOHAL, S. LA ROSA, et al. "PHOTOEMISSION MICROSCOPY INVESTIGATION OF BURIED p–n GaAs HOMOJUNCTIONS AND Al/n-GaAs SCHOTTKY BARRIERS." Surface Review and Letters 09, no. 01 (February 2002): 249–54. http://dx.doi.org/10.1142/s0218625x02002154.

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A natural application of the emerging technique of photoemission microscopy to the study of semiconductor interfaces involves measuring a device in cross section to directly determine heterojunction parameters. We present here results on p–n GaAs homojunctions, which served as a prototype system to demonstrate the applicability of this technique to buried semiconductor interfaces. We also describe preliminary measurements of the electrostatic potential profile across Al/GaAs Schottky junctions.

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