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The Gibbs free energy of two highly charged plates immersed in an electrolyte solution in a finite container is investigated using mean field theory. Adiabatic potential of the charged plates, which is derived from the Gibbs free energy, has a long-range weak attractive part and medium range strong repulsive part under the Dirichlet boundary condition. From comparison with the Helmholtz adiabatic potential, it is proved that the two adiabatic potentials have qualitatively the same structure of a repulsive component and an attractive component and that the Gibbs adiabatic potential shows the stronger attractive effect.

This work studies the adsorption behavior of methylene blue (MB) from water by bone char (BC). The effects of pH, initial dye concentration and dosage of adsorbent on the adsorption were investigated. It was found that the adsorption capacity of MB was affected by the mount of OH${}^{-}$, initial concentration gradient driving force of MB, the surface charge and adsorption site of BC.

The strategy of introducing the chromophores with low ground state dipole moment had been discussed to overcome the effect of the electrostatic interaction between the chromophores in the poled polymer films on its nonlinearity. As a result, the effective nonlinear optical coefficient d₃₃ of the poled films, containing the chromophores with μ_g in the range of 3.5–5.5 D, will enhance at least 15%, even over 30%, compared to that of 7.5 D if the first hyperpolarizabilities (β) of chromophores are in the same magnitudes. And, under the above assumption, the same level of the d₃₃ could even be achieved by utilizing the chromophores with μ_g as low as 2.2 D.

Tetramer of lactose repressor (LacR) protein plays an essential role in controlling the transcription of DNA. The previous experimental studies elucidated that the carboxyl-terminal domain of LacR is important for the tetramerization of LacR. In the present study, we investigated stable structures of monomers, dimers and tetramer of LacR by molecular mechanics and molecular dynamics simulations, based on AMBER force field to elucidate the effect of the tetramerization domain on LacR structure. The obtained stable structures for both the LacR tetramers, with and without the tetramerization domain, indicate that this domain is essential for constructing a compact structure of LacR tetramer. On the other hand, this domain does not affect the structure of LacR dimer. Furthermore, we investigated the charge distributions and binding energies for these stable structures by the charge equilibration and semiempirical molecular orbital methods. The results elucidate how the removal of the tetramerization domain causes the change in the electrostatic interaction between LacR dimers in the LacR tetramer, resulting in the separation of LacR dimers without the domain.

Electrostatic interaction conductive hybrids were prepared in water/ethanol solution by the sol-gel process from inorganic sol containing carboxyl group and water-borne conductive polyaniline (cPANI). The electrostatic interaction hybrids film displayed 1–2 orders of magnitude higher electrical conductivity in comparison with common hybrids film, showing remarkable conductivity stability against water soaking. Most strikingly, it displayed ideal electrochemical activity even in a solution with pH = 14, which enlarged the conducting polyaniline application window to strong alkaline media.

Cytochrome c₃ from Desulfovibrio vulgaris (Miyazaki) is an electron transfer protein containing four hemes per molecule. Its physiological electron transfer partner is the hydrogenase which catalyzes reversible oxidation of hydrogen. The complex formation between cytochrome c₃ and hydrogenase is caused by electrostatic interaction, because cytochrome c₃ is a basic protein and hydrogenase is an acidic protein. As cytochrome c₃ has 20 lysine residues among 108 amino acids, the positive charges of some lysine residues may play an important role in the interaction with hydrogenase. To clarify the role of positive charge of lysine residue, the positive charge was changed to neutral or negative charge using chemical modification and site-directed mutagenesis. When the positive charges around heme IV were changed, the hydrogen evolution rate with hydrogenase decreased. The affinity between hydrogenase and mutated cytochrome c₃ (K57Q, K57E, K72Q, K94Q, K94E) were not affected. On the other hand, the affinity of K72E cytochrome c₃ for hydrogenase was very low. These results suggest that the positive charge around heme IV plays an important role in the electrostatic interaction with hydrogenase in hydrogen evolution.

A tetraanionic porphyrin and a tetracationic metallomacrocycle formed a layered two-dimensional nanosheet through multiple electrostatic interactions. X-ray crystallography revealed that the sheet is an ionic lattice composed of $\pi$-conjugated components

A new type of pure organic 5,10,15,20-tetra (4-hydroxyphenyl) porphyrin (TPPH)/$g$-C₃N₄ nanohybrid was prepared to expand the light absorption range of graphitic carbon nitride materials. The morphology and structure of the composites were systematically characterized by scanning electron microscope, transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Results show that after the introduction of TPPH, the visible light area optical absorption of the composite sample increased significantly under the noncovalent interaction of TPPH and $g$-C₃N₄, and the electrochemical impedance spectroscopy and $I$–$T$ measurements confirmed the improved charge separation efficiency of the sample and showed excellent photocatalytic hydrogen production capacity. Under full spectrum irradiation, the hydrogen production of 1.67% TPPH/$g$-C₃N₄ without adding co-catalyst reached 10.87mmol$\cdot {\mathrm{\text{g}}}^{-1}\cdot {\mathrm{\text{h}}}^{-1}$, about 2.68 times that of pure $g$-C₃N₄ (4.06mmol$\cdot {\text{g}}^{-1}\cdot {\mathrm{\text{h}}}^{-1}$), which showed effective promotion of the electron transfer between TPPH and $g$-C₃N₄.

We give a detailed analysis of the interaction between overlapping charged balls, depending on the distance between them and their sizes. If one of the balls is entirely inside another ball, the interaction force is strictly proportional to the distance between the balls’ centers. This force has a maximum when some partial balls overlap depending on the ratio of their radii. For example, if the balls are the same, then the maximum corresponds to the distance between the centers equal to the balls’ radius. At small relative displacements of oppositely charged balls, they should perform harmonic oscillations around their common center of mass. The paper is addressed to undergraduates who deal with modern electrostatics.

Metal ions are ubiquitous in complex with proteins and play key roles in protein structure and function. The ion-protein interactions are electrostatic delicate in nature, however, the description of electrostatic interactions could be problematic in conventional additive fixed-charge force fields. With empowered computational sources going beyond the common approximations, many efforts have been done to take account in more elaborate electrostatic description in molecular modeling using more sophisticated physical models and dilated algorithms/implementations. Here we review rencent progress in advanced polarizable models and new impletment approaches towards accurate electrostatics and highlight some successful application cases in ion-protein interaction systems in recent years.

The stability of an organic compound depends on its nature and the environment in which it is placed. It depends on the presence or absence of reagents (acid, base, oxidizing agent, reducing agent, light, etc.) and catalysts. The stability may not be the same in the solid, liquid or gaseous state. In a homogenous solution, the stability might be affected by the polarity of the solvent and its concentration. For instance a polar solvent favors ionization. In a non-polar solvent ionization is difficult. In the gas phase ionization never occurs. In the gas phase and in solution stability depends on pressure and the presence of impurities. We are interested here in the thermal stability of pure compounds in the gas phase or in non-polar solvents under one atmosphere…

The cadmium^II complex [Cd₂(C₄H₄O₄)₄(C₇H₆N₂)₂Cl₂], the Cd^II atom is located on a twofold axis and is coordinated by two succinic acid anions and two benzimidazole molecules and two chloride ions in a symmetrical octahedral geometry. The succinic acid ligand chelates to the Cd^II atom through its carboxyl O atom, with Cd-O bond distances (2.248(3)Å). Adjacent complex link to each other via hydrogen bonds forming the three-dimensional supramolecular structure.