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The chemical, or chemisorption, part of colloidal interaction free energy is revisited. Consistent incorporation of nonelectrostatic interactions in the chemical potential for the constant potential and charge regulation boundary conditions is developed. This gives rise to shifted adsorption equilibria, and thereby a shift in the predicted surface electrostatic potential. It also results in an additional component previously unaccounted for in the total double layer interaction force. The altered force leads to the need of recalibrating electrostatic surface potentials and equilibrium constants when fitting to experimental force data. A numerical illustration is presented using ionic dispersion potentials for mica surfaces interacting across NaCl at various concentrations. The new force component due to ionic dispersion is typically repulsive and exceeds entropic repulsion in magnitude. These results suggest that the effect of ionic dispersion is more profound than previously believed, even at ...
Electrostatic free energy is useful for correlating structure with function in proteins in which ionizable groups play essential functional roles
We explored the influence of external electric fields (EEFs) on the stability of a glycine dipeptide model radical using high-level quantum chemical methods. Remotely located ions (Cl-/Na+) are used to implement EEF effects. The effects of these ions are reproduced using background point charges and oriented EEFs. Remote charges as far as 900 pm from the C-alpha radical center can be significantly stabilizing or destabilizing as a function of their relative orientation. The magnitude of these effects is also strongly dependent on the distance between the radical center and the charge location. After examining the strengths and weaknesses of some frequently used quantum mechanics methods in describing these effects properly, a comparison is made on the stability of dipeptide radicals bearing protonable or deprotonable side chains. In this group, the stability of the respective C-alpha radicals mainly depends on the preferred orientation of the charge-carrying side chain. ...
Organic photoacids with enhanced acidities in the excited states have received much attention both experimentally and theoretically because of their applications in nanotechnology and chemistry. In this study, we investigate excited-state acidities of 14 hydroxyl-substituted aromatic photoacids, with a focus
High dielectric contrast between water and hydrocarbons provides a useful method for distinguishing between producible layers of reservoir rocks and surrounding media. Dielectric response at high frequencies is related to the moisture content of rocks. Correlations between the dielectric permittivity and specific surface area can be used for the estimation of elastic and geomechanical properties of rocks. Knowledge of dielectric loss-factor and relaxation frequency in shales is critical for the design of techniques for effective hydrocarbon extraction and production from unconventional reservoirs. Although applicability of dielectric measurements is intriguing, the data interpretation is very challenging due to many factors influencing the dielectric response. For instance, dielectric permittivity is determined by mineralogical composition of solid fraction, volumetric content and composition of saturating fluid, rock microstructure and geometrical features of its solid components and pore space,
The electrostatic potential at ,math,\bar r,/math, generated by the total charge distribution, ,math,\rho ^{tot},/math,, of a periodic system is given by ,math,V(\bar r) = \sum\limits_n {\int {\rho ^{tot} (\bar r - \bar R_n )} } ,\bar r - \bar r,^{ - 1} d\bar r,/math, The summation extends to all direct lattice vectors, the prime on the integral sign indicating that an infinitesimal region about ,math,\bar r = \bar r,/math, is excluded from the domain of integration to avoid divergent nuclear self-interaction terms that would otherwise arise in the electrostatic energy per cell. ,math,\rho ^{tot},/math, may be decomposed into electronic and nuclear components. In this paper, ,math,V(r),/math, was calculated by means of the CRYSTAL98 program using the Khon-Sham Hamiltonian with the gradient-corrected Perdew-Becke-Ernzerhof (PBE) exchange potential. The topology of ,math,V(r),/math, was analyzed using an algorithm developed in the authors lab in the same way that those developed for the study ...
The electrostatic potential at ,math,\bar r,/math, generated by the total charge distribution, ,math,\rho ^{tot},/math,, of a periodic system is given by ,math,V(\bar r) = \sum\limits_n {\int {\rho ^{tot} (\bar r - \bar R_n )} } ,\bar r - \bar r,^{ - 1} d\bar r,/math, The summation extends to all direct lattice vectors, the prime on the integral sign indicating that an infinitesimal region about ,math,\bar r = \bar r,/math, is excluded from the domain of integration to avoid divergent nuclear self-interaction terms that would otherwise arise in the electrostatic energy per cell. ,math,\rho ^{tot},/math, may be decomposed into electronic and nuclear components. In this paper, ,math,V(r),/math, was calculated by means of the CRYSTAL98 program using the Khon-Sham Hamiltonian with the gradient-corrected Perdew-Becke-Ernzerhof (PBE) exchange potential. The topology of ,math,V(r),/math, was analyzed using an algorithm developed in the authors lab in the same way that those developed for the study ...
Abstract: We investigate the spectral and transport properties of parallel double-quantum-dot (DQD) system with interdot tunneling coupling in both the equilibrium and nonequilibrium cases. The special geometry of DQD system is considered, in which each dot is connected to two leads by the tunneling barriers. With the help of Keldysh nonequilibrium Green function technique and the equation-of-motion approach, the spectral function and the conductance spectra of DQD system are calculated in two cases with and without the intradot Coulomb interaction, respectively. The exact calculation is performed in the absence of intradot Coulomb interaction. For the case with intradot Coulomb interaction, the Hartree-Fock approximation is applied to truncate the equation of motion for the high-order Green functions at high temperatures. The phenomenon of correlated electron transport is clearly shown in the linear conductance of each dot in the presence of interdot tunneling when setting one dot level and ...
In his editorial, Andersen 1999 questions the applicability of the mean field approximation for the situation of ions in the narrow pore of the channel: "Finally, notwithstanding the utility of the mean field approximation, is it appropriate for narrow channels that are occupied by only a few ions?" Similar doubts are mentioned in other Perspectives. Therefore, a critical inspection of the concepts of mean fields and mean field approximation in statistical physics applied to biological ion channels is timely. Whereas the introduction of mean fields generally does not involve any approximation, the mean field approximation is necessary to account for the nonlinear long-range electrostatic interaction between permeant ions.. During a 10-pA, 1-s channel opening, 6.3 · 107 ions pass the channel. With a time resolution in the millisecond range, the experimental mean current samples ,60,000 ions. Passing the bottleneck of the channel each of those ions will see different forces. Side chains at the ...
1L42: Cumulative site-directed charge-change replacements in bacteriophage T4 lysozyme suggest that long-range electrostatic interactions contribute little to protein stability.
Electrostatics (part 2) Electric Fields This Scientific content most probably shows video related to topic: Lec 109 - Electrostatics (part 2). However in few cases, video content could be different than the title.
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Classical model for two-proton correlations in intermediate-energy heavy-ion reactions: The Coulomb interaction between two protons sequentially evaporated from
the capacitance of a capacitor that has an equal and opposite charge of 1 coulomb on each plate and a voltage difference of 1 volt between the plates. ...
NaCl is an ionic compound. As an ionic compound, it possesses a crystal-lattice structure with countless ions of opposite charge that are electrically bound to each other. Ionic bonding consists of...
According to the big bang theory for the origin of the universe, equal amounts of matter and antimatter should have formed. Antimatter is the same as matter except that each has the opposite charge.. ...
According to the big bang theory for the origin of the universe, equal amounts of matter and antimatter should have formed. Antimatter is the same as matter except that each has the opposite charge.. ...
You are viewing an interactive 3D depiction of the molecule [(1r)-2-(6-aminopurin-9-yl)-1-methyl-ethoxy]methyl-[hydroxy(phosphonooxy)phosphoryl]oxy-phosphinic acid (C9H16N5O10P3) from the PQR.
You are viewing an interactive 3D depiction of the molecule 4,4-[{3-[(2-naphthylsulfonyl)amino]-2,6-pyridinediyl}bis(oxy)]dibenzenecarboximidamide (C29H24N6O4S) from the PQR.
The glue contains polymers bond to biological tissues, which are contained in three mechanism which includes the electrostatic attraction to negatively
Coulombs law The fundamental law of electrostatics states that the force between two charged particles is directly proportional to the product of their charges and inversely proportional to the square of the distance between them.
We consider a system made of a positive Vlasov-Poisson plasma and $N$ positive charges in $\R^2$, interacting among themselves and with the plasma via the Coulomb force. We prove an existence and uniqueness theorem for the system in case the charges are initially apart from the plasma.
One of the more idiotic charges that sometimes come my way is that if difference is made a criteria for existence, then we are no longer able to make distinctions. I am not sure whether people who advance such charges are idiots, lack the ability to reflect, or have simply become stupid as a result…
A combined theoretical and experimental study of the ionized dimers of thymine and adenine, TT, AA, and AT, is presented. Experimentally observed and computed adiabatic and vertical ionization energies (IEs) for monomers and dimers as well as thresholds for the appearance of the protonated species are report
2014) Correction to "Effect of Nonelectrostatic Ion Interactions on Surface Forces Involving Ion Adsorption Equilibria". The Journal of Physical Chemistry C, 118 (36). p. 21299. ...
TY - JOUR. T1 - Cell-cycle-dependent Changes of the Negative Surface Charges in L929 Cells. AU - Doi, Akitaka. AU - Tokuda, Masaaki. AU - Itano, Toshifumi. AU - Matsui, Hideki. AU - Ohmura, Yoshiaki. AU - Hatase, Osamu. PY - 1984/1/1. Y1 - 1984/1/1. N2 - The negative charges of cell surface were studied by the adsorption method of methylene blue in the synchronized cultures of L929 cells and its spontaneously transformed cell strain.The negative surface charges of the transformed cells were twice those of the original cells through all cell cycle phases.The surface charges cell-cycle-dependently changed in both cell systems and there were two maximum peaks at early Gx and S phase.. AB - The negative charges of cell surface were studied by the adsorption method of methylene blue in the synchronized cultures of L929 cells and its spontaneously transformed cell strain.The negative surface charges of the transformed cells were twice those of the original cells through all cell cycle phases.The ...
Cámara CL & N Wilke, Chem. Phys. Lipids, 2017 Polysaccharides have been associated with various biological functions through their binding to membranes, but their specific role is still under debate. The aim of this work was to study the interaction of cationic and anionic polysaccharides with anionic and zwitterionic monolayers, at different subphase compositions, thus analyzing the influence of electrostatics on the interaction. The consequent effect of the polymer-lipid binding on the film properties was studied, with special interest in monolayer dynamics. The results indicate that electrostatic interactions play an important role in polymer-membrane affinity, and that the polymers formed a sub-layer, which increased the shear viscosity of the interface. The interacting polymer, even when it did not penetrate the lipid film, induced a polymer-like behavior of the monolayer regarding its dynamics: the whole film (polymer+lipid) became very viscous. As a consequence, the dynamic of the ...
TOP 140+ Electrostatics Multiple choice Questions and Answers: Question 1: What is electrostatics charge?, Question 2: What do you mean by electrostatics?, Question 3: How can the buildup of electrostatic charge be prevented?
The possible electrostatic mechanisms of ion ejection from laser-exposed regions where ultrafast phase-transitions (to transient states with low carrier transport properties) occur are not discussed in this work. 2. Fast electron transport and Coulomb explosion... SURFACE ,--^ AuxlOO 0 . • • • s i x 100 Q -J yu u. o cc 31 / 5 ^ ^ ^ - - ^ R I T I C A L ELECTRIC FIELD H o 10 UJ _J HI 0 2 4 6 DISTANCE [nm] 8 10 Figure 5. Spatial bulk profiles of the electric field induced by ultrafast laser radiation in metals, semiconductors, and dielectrics at time moments corresponding to the maximum values of the electric field for each material. 71, 162 Zhakhovskii Vasilii, Nishihara Katsunobu, Fukuda Yuko, and Shimojo Shinji, 2004, A New Dynamical Domain Decomposition Methodfor Parallel Molecular Dynamics Simulation on Grid, Annual Progress Report 2003, Institute of Laser Engineering Osaka University, 2004, p. , 1999, Shock wave structure in Lennard-Jones crystal via molecular dynamics, Phys. Rev. , ...
Many existing carriers encapsulate drugs through the long-range electrostatic interactions - the carrier attracts oppositely charged medicine. Our method does not deal with the electrostatics at all. Filling in the nanogel by the guest molecules, locking them in the cavity and further release arecontrolled by the temperature. Therefore, the medicines themselves can be both charged and neutral, says one of the Russian co-authors of the article, Professor Igor Potemkin. According to the authors, there are other tools to trigger the release of drugs, for example, an external magnetic field and pH. But in each case researchers face the problem of efficiency of the drug release.. The scientists decided to use the gel nano-capsules that were previously undervalued as the carrier systems. Their main problem, which held back the interest towards them, was that the capsules stuck together with their neighbors (lost colloidal stability) when trying to upload drugs. Such behavior made the delivery ...
The COSMO-RS method was used for calculation of blood-brain partition coefficients based on sigma-moments. These five sigma moments are: surface area of the solute, the negative of the total charge, another noment corresponds to the negative of the electrostatic interaction energy of the solute with a dielectric continuum, and the third-order moment does not have a simple interpretation plus acceptor and donor moments.. The calculation and interpretation of large descriptor datasets can be avoided and the quantum chemical definition of the sigma-moments is applicable to almost all kinds of organic compounds. A minor disadvantage is the computational time for new compounds which includes quantum mechanical calculations (10 min per compound), however this can be diminished by using compute clusters or COSMOfrag a precalculated dataset of sigma-profiles).. ...
The extrapolation of small-cluster exact-diagonalization calculations and the Monte Carlo method is used to study the spin-one-half Falicov-Kimball model extended by the spin-dependent Coulomb interaction (J) between the localized f and itinerant d electrons as well as the on-site Coulomb interaction (U_{ff}) between the localized f electrons. It is shown that in the symmetric case the ground-state phase diagram of the model has an extremely simple structure that consists of only two phases, and namely, the charge-density-wave phase and the spin-density-wave phase. The nonzero temperature studies showed that these phases persist also at finite temperatures. The same calculations that we performed for unsymmetric case showed that charge and spin ordering can be destroyed simultaneously or consecutively ...
... The removal of Ni(II) by foam fractionation is brought about by the electrostatic mechanism. From removal and zeta potential measurements, it clearly demonstrates that Ni**2** plus and NiOH** plus ions become associated with the dodecylsulfonate coated (negative charge) N//2 gas bubbles. The optimal Ni(II) to NaDS (molar ratio) is 0. 2. The Ni**2** plus species forms moderately strong complexes with dodecylsulfonate ions.
Whole-proteome distributions of protein isoelectric point (pI) values in different organisms are bi- or trimodal with some variations. It was suggested that the observed multimodality of the proteome-wide pI distributions is associated with subcellular localization-specific differences in the local pI distributions. However, the factors responsible for variation of the intracellular localization-specific pI profiles have not been investigated in detail. In this work, we explored proteome-wide pI distributions of 32,138 human proteins predicted to reside in 10 subcellular compartments, as well as the pI distributions of experimentally observed lysosomal and Golgi proteins. The distributions were found to differ significantly, although all of them adhered to the major recurrent bimodal pattern. Grossly, acid-biased and alkaline-biased patterns with various minor statistical features were observed at different subcellular locations. Bioinformatics analysis revealed the existence of strong statistically
Measured values of the swelling pressure of charged proteoglycans (PG) in solution (Williams RPW, and Comper WD; Biophysical Chemistry 36:223, 1990) and the ionic strength dependence of the equilibrium modulus of PG-rich articular cartilage (Eisenberg SR, and Grodzinsky AJ; J Orthop Res 3: 148, 1985) are compared to the predictions of two models. Each model is a representation of electrostatic forces arising from charge present on spatially fixed macromolecules and spatially mobile micro-ions. The first is a macroscopic continuum model based on Donnan equilibrium that includes no molecular-level structure and assumes that the electrical potential is spatially invariant within the polyelectrolyte medium (i.e. zero electric field). The second model is based on a microstructural, molecular-level solution of the Poisson-Boltzmann (PB) equation within a unit cell containing a charged glycosaminoglycan (GAG) molecule and its surrounding atmosphere of mobile ions. This latter approach accounts for the ...
The protonation state of embedded charged residues in transmembrane proteins (TMPs) can control the onset of protein function. It is understood that interactions between an embedded charged residue and other charged or polar residues in the moiety would influence its pKa, but how the surrounding environment in which the TMP resides affects the pKa of these residues is unclear.
Simulations of water using the exnteded simple point charge (SPC/E) model at temperatures between 190 and 330 K were performed using molecular dynamics techniques. A maximum in the density at 1 bar pressure was found to occur at 235 K. The energies and diffusivities are also reported. The SPC/E-modeled water exhibits a glass transition ∼177 K. No crystallization events were observed during the course of the long simulations. © 1994 American Institute of Physics ...
Control over the motional degrees of freedom of atoms, ions, and molecules in a field-free environment enables unrivalled measurement accuracies but has yet to be applied to highly charged ions (HCIs), which are of particular interest to future atomic clock designs and searches for physics beyond the Standard Model. Here, we report on the Coulomb crystallization of HCIs (specifically 40Ar13+) produced in an electron beam ion trap and retrapped in a cryogenic linear radiofrequency trap by means of sympathetic motional cooling through Coulomb interaction with a directly laser-cooled ensemble of Be+ ions. We also demonstrate cooling of a single Ar13+ ion by a single Be+ ion-the prerequisite for quantum logic spectroscopy with a potential 10−19 accuracy level. Achieving a seven-orders-of-magnitude decrease in HCI temperature starting at megakelvin down to the millikelvin range removes the major obstacle for HCI investigation with high-precision laser spectroscopy.. ...
This is the approach we use in this work. By integrating CPW TLines on top of porous Si and measuring their S-parameters, we extract porous Si. dielectric parameters by combining the experimental results with electromagnetic simulations and conformal mapping calculations. This method has been described in detail in [13, 14], and the results have been proven to be in very good agreement with full-wave EM simulations [14]. In Figure 4 the extracted dielectric permittivity of three PSi layers with 70%, 76%, and 84% porosity using the above method are depicted in full black circles. The PSi layers were fabricated on a p+-type Si wafer with resistivity 1 to 5 mΩ.cm and had a surface area of 4 cm2. NU7026 Identical transmission lines were integrated on all three samples (see Figure 2b). The obtained results were compared with those obtained using Vegards, Maxwell-Garnetts and Bruggemans models for PSi by applying formulas (1) to (3) given above. From Figure 4, it can be seen that the values of the ...
TBI :: DESCRIPTION TBI (Tightly Bound Ion Model ) predicts the electrostatic free energy, the different free energy components, the average binding fraction of ions, and the most probable ion binding modes for a give
Industrys need to predict the lifetime of adhesively bonded joints has been met by the development of a wide variety of techniques. One particular approach utilises the fact that adhesives and the joints they form can be susceptible to moisture attack. The ingress of moisture into, and through, an adhesive or polymer is termed water permeation. Such a phenomenon can be measured extremely accurately (e.g. through mass change, dielectric permittivity, etc) and it has been shown that for particular systems and environments, a good correlation can be made between the accelerated ageing protocol and in-service failure. This approach has been studied extensively for application within the electronics sector where adhesive/polymeric systems are used both to retain components and coat them. ...
We cordially invite you to a lecture of Yvon Jaillais from Laboratory of Plant Development and Reproduction, Ecole Normale Superieure of Lyon, France which will be held on Wednesday, on June 15th at 14:00 in the reading room of the building B1 of the Institute of Experimental Botany, Lysolaje. The title of the lecture is „A PI4P-driven electrostatic field controls cell membrane identity and signaling in plants . Yvon Jaillais (http://www.ens-lyon.fr/RDP/SiCE/RK.html) is guest of the Laboratory of Cell Biology, IEB.. ...
read mol pqr 1OED.pqr mol pqr ion.pqr mol pqr complex.pqr end elec name protein mg-auto mol 1 dime 97 97 97 cglen 100.000000 100.000000 105.000000 fglen 10 10 10 cgcent mol 3 fgcent mol 2 # NaCl ionic strength in mol/l ion 1 0.15 0.95 # sodium ions ion -1 0.15 1.81 # chloride ions lpbe bcfl mdh pdie 2.0 # protein and faux-lipid sdie 78.5 # Eisenberg and Crothers Phys. Chem. book 1979 srfm smol chgm spl2 srad 1.4 swin 0.3 sdens 10.0 temp 300 # gamma 0.105 # Uncomment for old versions of APBS -- deprecated for APBS 1.0.0 calcenergy total calcforce no end elec name ion mg-auto mol 2 dime 97 97 97 cglen 100.000000 100.000000 105.000000 fglen 10 10 10 cgcent mol 3 fgcent mol 2 # NaCl ionic strength in mol/l ion 1 0.15 0.95 # sodium ions ion -1 0.15 1.81 # chloride ions lpbe bcfl mdh pdie 2.0 # protein and faux-lipid sdie 78.5 # Eisenberg and Crothers Phys. Chem. book 1979 srfm smol chgm spl2 srad 1.4 swin 0.3 sdens 10.0 temp 300 # gamma 0.105 # Uncomment for old versions of APBS -- deprecated for ...
A novel dynamic charge-charge interaction between B56 and a subset of PP2A-B56 substrates is essential for substrate specificity, dephosphorylation and, for KIF4A, binding condensin I.
Tony Yeung, Bryan Heit, Jean-Francois Dubuisson, Gregory D. Fairn, Basil Chiu, Robert Inman, Andras Kapus, Michele Swanson, Sergio Grinstein ...
We will probe the interaction induced by lipid membranes between included molecules (and other nano-objects). This study presents both a fundamental interest, from the point of view of soft matter physics, and a relevance to understanding the activity of important biological molecules, such as native membrane proteins and antimicrobial peptides. In particular, the cytotoxic activity of the latter is directly related to the composition of the membrane (charge, thickness, presence of cholesterol) rather than to specific chemical recognition. It has long been posited that highly simplified descriptions (e.g. in terms of hydrophobic matching) capture the essence of the process, but the extensive body of theoretical and numerical work cannot be validated and refined due to the lack of experimental results. We intend to measure accurately the interaction between membrane inclusions. Highly aligned lipid multilayers, doped with antimicrobial peptides and fully hydrated (in excess water) will be studied using
The characteristics of both charges can be well understood, if we analyze the points of distinction between the two. They are as follows:. 1. A fixed charge is created on some property capable of being defined. A floating charge, on the other hand, shall be generally created upon the whole of the companys property, including movable and immovable and also property, which is subject to a fixed charge.. 2. The company cannot deal with a property, which is subject to a fixed charge. But, it can deal with all the properties, which are subject to a floating charge.. 3. A fixed charge shall not become a floating charge. A floating charge, upon the occurrence of certain events may become a fixed charge.. 4. If a fixed charge is created over a property, which is subject to a floating charge, the fixed charge shall get priority, whereas if a floating charge is created over the assets, which are subject to a fixed charge, the charges shall not get any priority.. ...
ELECTROSTATICS - A COLOURFUL APPLICATION by Michael Liang | This newsletter was created with Smore, an online tool for creating beautiful newsletters for for educators, nonprofits, businesses and more
The importance of electrostatic interactions in soft matter and biological systems can often be traced to non-uniform charge effects, which are commonly described using a multipole expansion of the corresponding charge distribution. The standard approach when extracting the charge distribution of a given system is to treat the constituent charges as points. This can, however, lead to an overestimation of multipole moments of high order, such as dipole, quadrupole, and higher moments. Focusing on distributions of charges located on a spherical surface - characteristic of numerous biological macromolecules, such as globular proteins and viral capsids, as well as of inverse patchy colloids - we develop a novel way of representing spherical surface charge distributions based on the von Mises-Fisher distribution ...