Vinyl polymerization. 422. Initiation mechanism of uncatalyzed polymerization by polyethyleneglycol

The initiation mechanism on the radical polymerization of vinyl monomers by polyethyleneglycol (PEG-300) in aqueous solution was studied. The initiating radical species were determined by means of the spin trapping technique. They were concluded to be generated by the hydrogen atom transfer from the monomer adsorbed at the ether group of PEG-300 to the free monomer.     

Vinyl polymerization. 416. Polymerization of vinyl monomer initiated by polyethyleneglycol

The polymerization of vinyl monomer initiated by polyethyleneglycol (PEG) in aqueous solution was carried out at 85°C with shaking. Acrylonitrile (AN), methyl methacrylate (MMA), and methacrylic acid were polymerized by PEG–300 (M?_n = 300), whereas styrene was not. The effects of the amounts of monomer and PEG, the molecular weight of PEG, and the hydrophobic group at the end of PEG molecule on the polymerization were studied. The selectivity of vinyl monomer and the effect of the hydrophobic group are discussed according to “the concept of hard and soft hydrophobic areas and monomers.” The kinetics of the polymerization was investigated. The overall activation energy in the polymerization of AN was estimated as 37.9 kJ mol^?1. The polymerization was effected by a radical mechanism.     

Three-dimensional morphological chirality induction using high magnetic fields in membrane tubes prepared by a silicate garden reaction

Using a vertical superconducting magnet (max. 15 T), we studied magnetic field effects on membrane tube morphology prepared by a silicate garden reaction. At zero field, semipermeable membrane tubes grew upward when metal salts were added to a sodium silicate aqueous solution. In the presence of a magnetic field (15 T, downward) right-handed helical membrane tubes grew along a glass vessel's inner surface when magnesium chloride and copper sulfate were added. Referring to membrane tubes by the names of metal cations used in their preparation, in the case of Mg(II) and Zn(II) membrane tubes, the left-handed helical tubes grew when the field direction was reversed upward. The left-handed helical Mg(II) membrane tubes grew in the magnetic field when a glass rod was placed in a vessel. Mg(II) and Zn(II) tubes, separate from a vessel wall, grew in a twisted shape in the magnetic field. In situ observation of the solution's motion during the reaction revealed that the Lorentz force on the outflow from the opened top of the hollow membrane tube induced convection of the solution near the tube exit, engendering chiral growth of the membrane tubes. Relative orientation of the outflow and a boundary (a vessel wall or glass rod surface) helped to determine the convection's direction.     

Inhibitory activities of novel pyrimidine derivatives on the contact hypersensitivity reaction

In order to obtain novel topically applied anti-inflammatory compounds containing an inexpensive anti-oxidative moiety without chirality, we synthesized compound 2c derivatives having a di-tert-butylphenol moiety, and evaluated by topical administration their anti-inflammatory potentials on picryl chloride-(PC) induced contact hypersensitivity reaction (CHR) in mice. In the course of our structure-activity relationship (SAR) studies on the pyrimidine or the anti-oxidative moiety and the linker between them, the most potent compounds (10, 11) were obtained by the insertion of a C2 unit in compound 2c. The potencies of these compounds were 2-fold greater than that of 1. Compounds 10 and 11 were considered to be useful lead compounds having inexpensive anti-oxidative moieties without chirality.     

Simultaneous determination of 16 estrogens,dehydroepiandrosterone and their glucuronide and sulfate conjugates in serum using sodium cholate micelle capillary electrophoresis

The simultaneous determination of 16 estrogens, dehydroepiandrosterone (DHEA) and their glucuronide and sulfate conjugates by micellar electrokinetic chromatography (MEKC) with sodium cholate micelle is reported. Sodium cholate, sodium dodecylsulfate (SDS) and alpha-, beta-, gamma-cyclodextrins were studied as micelle reagents in the pH range of 7.0-10.0. Estrogens, DHEA and their glucuronide and sulfate conjugates were separated using a 50 cm x 50 microm capillary with 10 mM borate-phosphate buffer (pH 8.0) containing 50 mM sodium cholate as carrier. The method could simultaneously determine 1.0-1000 microg/mL of steroids and metabolites in 100 microL of serum by photometric detection at 214 nm within 14 min and 80 ng/mL steroids could be determined by using 2.0 mL of serum. The relative standards deviations were 6.7-7.7% at 10 microg/mL in serum. The recoveries were 89.1-92.0% with 10 microg/mL serum samples.     

Surface Activities of Calix[4] resorcinarenes Bearing Four Hydrophobic Chains and Its Sol ubilization for Organic Compounds

ＩｎｔｒｏｄｕｃｔｉｏｎＩｎｃｌｕｓｉｏｎｃｏｍｐｏｕｎｄｓｈａｖｅｂｅｅｎｎｏｔｅｄｉｎｒｅｃｅｎｔｙｅａｒｓａｎｄｒｅｓｏｒｃｉｎｏｌ ｔｙｐｅｃａｌｉｘ [4 ]ａｒｅｎｅｈａｓｂｅｅｎｓｔｕｄｉｅｄｆｏｒｔｈｅｉｒｉｎｃｌｕｓｉｏｎａｂｉｌｉｔｉｅｓｂｙＳｃｈｅｉｄｅｒａｎｄＢｕｇｌｅｒｅｔａｌ[1— 3] .Ｔｈｅｐｏｌｙｏｌｍｏｉｅｔｉｅｓｉｎｃａｌｉｘ[4 ]ｒｅ ｓｏｒｃｉｎａｒｅｎｅｆｏｒｍｒｉｇｉｄｈｙｄｒｏｇｅｎ ｂｏｎｄｉｎｇｎｅｔｗｏｒｋｓ[4 ] ,ａｎｄｃａｌｉｘ [4 ]ｒｅｓｏｒｃｉｎａｒｅ…     

Dcdftbmd: Divide-and-Conquer Density Functional Tight-Binding Program for Huge-System Quantum Mechanical Molecular Dynamics Simulations

Dcdftbmd is a Fortran 90/95 program that enables efficient quantum mechanical molecular dynamics (MD) simulations using divide-and-conquer density functional tight-binding (DC-DFTB) method. Based on the remarkable performance of previous massively parallel DC-DFTB energy and gradient calculations for huge systems, the code has been specialized to MD simulations. Recent implementations and modifications including DFTB extensions, improved computational speed in the DC-DFTB computational steps, algorithms for efficient initial guess charge prediction, and free energy calculations via metadynamics technique have enhanced the capability to obtain atomistic insights in novel applications to nanomaterials and biomolecules. The energy, structure, and other molecular properties are also accessible through the single-point calculation, geometry optimization, and vibrational frequency analysis. The available functionalities are outlined together with efficiency tests and simulation examples. © 2019 Wiley Periodicals, Inc.     

GPU-Accelerated Large-Scale Excited-State Simulation Based on Divide-and-Conquer Time-Dependent Density-Functional Tight-Binding

The present study implemented the divide-and-conquer time-dependent density-functional tight-binding (DC-TDDFTB) code on a graphical processing unit (GPU). The DC method, which is a linear-scaling scheme, divides a total system into several fragments. By separately solving local equations in individual fragments, the DC method could reduce slow central processing unit (CPU)-GPU memory access, as well as computational cost, and avoid shortfalls of GPU memory. Numerical applications confirmed that the present code on GPU significantly accelerated the TDDFTB calculations, while maintaining accuracy. Furthermore, the DC-TDDFTB simulation of 2-acetylindan-1,3-dione displays excited-state intramolecular proton transfer and provides reasonable absorption and fluorescence energies with the corresponding experimental values. © 2019 Wiley Periodicals, Inc.