Charge Carriers Relaxation Behavior of Cellulose Polymer Insulation Used in Oil Immersed Bushing

Cellulose insulation polymer material is widely used in oil immersed bushing. Moisture is one of the important reasons for the deterioration of cellulose polymer insulation, which seriously threatens the safe and stable operation of bushing. It is significant to study the polarization and depolarization behavior of oil-immersed cellulose polymer insulation with different moisture condition under higher voltage. Based on polarization/depolarization current method and charge difference method, the polarization/depolarization current, interfacial polarization current and electrical conductivity of cellulose polymer under different DC voltages and humidity were obtained. Based on molecular-dynamics simulation, the effect of moisture on cellulose polymer insulation was analyzed. The results show that the polarization and depolarization currents become larger with the increase in DC voltage and moisture. The higher applied voltage will accelerate the charge carrier motion. The ionization of water molecules will produce more charge carriers. Thus, high DC voltage and moisture content will increase the interface polarization current. Increased moisture content results in more charge carriers ionized by water molecules. In addition, the invasion of moisture will reduce the band width of cellulose polymer and enhance its electrostatic potential, so as to improve its overall electrical conductivity. This paper provides a reference for analyzing the polarization characteristics of charge carriers in cellulose polymer insulation.

Redetermination of the structure of 2-amino-8-thia-1,5-diazaspiro[4,5]dec-1-en-5-ium chloride monohydrate

The reaction of β-(thiomorpholin-1-yl)propioamidoxime with tosyl chloride in CHCl3 in the presence of DIPEA when heated at 343 K for 8 h afforded the title hydrated salt, C7H14N3S+·Cl−·H2O, in 84% yield. This course of the tosylation reaction differs from the result of tosylation obtained for this substrate at room temperature, when only 2-amino-8-thia-1,5-diazaspiro[4.5]dec-1-ene-5-ammonium tosylate was isolated in 56% yield. The structure of the reaction product was established by physicochemical methods, spectroscopy, and X-ray diffraction. The single-crystal data demonstrated that the previously reported crystal structure of this compound [Kayukova et al. (2021). Chem. J. Kaz, 74, 21–31] had been refined in a wrong space group. In the extended structure, the chloride anions, water molecules and amine groups of the cations form two-periodic hydrogen-bonded networks with the fes topology.

Dynamics and mechanism of dimer dissociation of photoreceptor UVR8

Photoreceptors are a class of light-sensing proteins with critical biological functions. UVR8 is the only identified UV photoreceptor in plants and its dimer dissociation upon UV sensing activates UV-protective processes. However, the dissociation mechanism is still poorly understood. Here, by integrating extensive mutations, ultrafast spectroscopy, and computational calculations, we find that the funneled excitation energy in the interfacial tryptophan (Trp) pyramid center drives a directional Trp-Trp charge separation in 80 ps and produces a critical transient Trp anion, enabling its ultrafast charge neutralization with a nearby positive arginine residue in 17 ps to destroy a key salt bridge. A domino effect is then triggered to unzip the strong interfacial interactions, which is facilitated through flooding the interface by channel and interfacial water molecules. These detailed dynamics reveal a unique molecular mechanism of UV-induced dimer monomerization.

Development and Validation of Fluorinated Amino Acid Parameters for use with the AMBER ff15ipq Protein Force Field

We developed force field parameters for fluorinated aromatic amino acids enabling molecular dynamics (MD) simulations of fluorinated proteins. These parameters are tailored to the AMBER ff15ipq protein force field and enable the modeling of 4, 5, 6, and 7F-tryptophan, 3F- and 3,5F-tyrosine, and 4F- or 4-CF3-phenylalanine. The parameters include 181 unique atomic charges derived using the Implicitly Polarized Charge (IPolQ) scheme in the presence of SPC/Eb explicit water molecules and 9 unique bond, angle, or torsion terms. Our simulations of benchmark peptides and proteins maintain expected conformational propensities on the μs-timescale. In addition, we have developed an open-source Python program to calculate fluorine relaxation rates from MD simulations. The extracted relaxation rates from protein simulations are in good agreement with experimental values determined by 19F NMR. Collectively, our results illustrate the power and robustness of the IPolQ lineage of force fields for modeling structure and dynamics of fluorine containing proteins at the atomic level.

Synthesis and structural characterization of a new heterometallicmolybdate coordination polymer based on a µ3-bridging amino alcohol

The reaction of Na2MoO4·2H2O with 2-amino-2-(hydroxymethyl)propane-1,3-diol (LH) in water at room temperature results in the formation of the heterometallic coordination polymer [Mo2O6L2(Na2(H2O)4)]·2H2O 1 (L = 2-amino-3-hydroxy-2-(hydroxymethyl)propan-1-olato). The structure of 1 consists of a neutral (Mo2O6) unit located on an inversion center. The Mo atoms exhibit hexa-coordination and are bonded to two terminal and two bridging oxido ligands, an alkoxide oxygen and the amine N atoms of an anionic ligand L– resulting in the formation of an edge-sharing {Mo2O8N2} bioctahedron. The Na+ cations of a centrosymmetric bis(μ2-aqua)-bridged (Na2(H2O)4)2+ unit are penta-coordinated and bonded to two symmetry related L– ligands via the oxygen atoms of their OH groups. The µ3-bridging tetradentate binding mode of L– results in the formation of a two-dimensional heterometallic coordination polymer. The constituents of 1 viz. (Mo2O6), (L)–, (Na2(H2O)4)2+ and lattice water molecules are interlinked with the aid of three varieties of hydrogen bonding interactions. The corresponding tungstate reported recently has been obtained through a similar synthetic protocol and is isostructural.

Spectral analyses of fresh and dry Hypericum perforatum L. Effects with colloidal nano silver 30 ppm

Spectral analyses of 1% water extracts of fresh and dry Hypericum perforatum L. and 1% dry H. perforatum with colloidal nano silver (NSPs) 30 ppm were conducted. The nano silver is standardised and patented by the Swiss company Evodrop. Non-equliblrium energy spectrum (NES) and Differential non-equliblrium energy spectrum (DNES) methods were used for the spectral analysis. A comparative analysis of 1% extracts of fresh and dry H. perforatum was performed in order to determine the local extremums for effects of nerve tissue conductivity at (-0.1112) eV, anti-inflammatory (-0.1212) eV, anti-tumor effects (-0.1387) eV. The results showed stimulating effect on the nervous system and improvement of nerve conduction (local extremums E=-0.1112 eV)(?=11.15 ?m) (?=897 cm-1), as well as anti-inflammatory effect (E = -0.1212 eV)( ?=10.23 ?m) (?=978 cm-1) and inhibition of development of tumor cells at a molecular level (E=-0.1387 eV) (?=8.95 ?m) (?=1117 cm-1). It was found that clusters of 16 and 15 water molecules are formed in the water herbal extracts of fresh H. perforatum and of dry H. perforatum with AgNPs 30 ppm. The fresh plant showed better results then the dry one. The addition of colloidal nano silver 30 ppm led to better results of the drug.