Silver(I)-Ion-Mediated Cytosine-Containing Base Pairs: Metal Ion Specificity for Duplex Stabilization and Susceptibility toward DNA Polymerases

Spectroscopic characterization of Ag^I-ion-mediated C-Ag^I-A and C-Ag^I-T base pairs found in primer extension reactions catalyzed by DNA polymerases was conducted. UV melting experiments revealed that C-A and C-T mismatched base pairs in oligodeoxynucleotide duplexes are specifically stabilized by Ag^I ions in 1:1 stoichiometry in the same manner as a C-C mismatched base pair. Although the stability of the mismatched base pairs in the absence of Ag^I ions is in the order C-A≈C-T>C-C, the stabilizing effect of Ag^I ions follows the order C-C>C-A≈C-T. However, the comparative susceptibility of dNTPs to Ag^I-mediated enzymatic incorporation into the site opposite templating C is dATP>dTTP≫dCTP, as reported. The net charge, as well as the size and/or shape complementarity of the metal-mediated base pairs, or the stabilities of mismatched base pairs in the absence of metal ions, would be more important than the stability of the metallo-base pairs in the replicating reaction catalyzed by DNA polymerases.     

Anti‐Sway Crane Control Considering Wind Disturbance and Container Mass

A method for estimating the sway angle using an observer has already been proposed. The state observer estimates the sway angle accurately and must use the detected sway angle value. However, the estimated sway angle has an error owing to rope length error, friction force, and wind. Moreover, the container mass cannot be determined, and therefore the observer parameter is not suitable. We already proposed robust antisway control for overcoming rope length error without adding a new sensor. Further, we designed a friction disturbance observer to cancel out the influence of the friction force. In this paper, we first propose a container mass estimation method when a crane system performs rolling up control. The observer parameter can be selected using the estimated mass value. Second, in crane parallel shift control, we propose a robust antisway control even when there is a wind disturbance. We design a wind disturbance observer and propose a wind disturbance estimator to separate the friction observer output from the wind disturbance observer output. We confirm through experiments that the proposed method can reduce vibration.     

Oxidation behavior of ytterbium silicide

Si-rich ytterbium silicide was fabricated by through an arc-melting technique for applying use as a bond coat material in an environmental barrier coating system. Evaluation of its potential was accomplished through oxidation tests in dry air and an inert atmosphere. The experimental results showed that the changes in weight and morphologies of ytterbium silicide observed after the tests depended on the oxygen partial pressure. Extensive oxidation and weight gain occurred after oxidation in air. In order to apply this material for hot structures, improvement of the oxidation resistance is needed.     

Polypropylene plasticization and photodegradation with a TiO2/poly(ethylene oxide)/methyl linoleate paint photocatalyst system

The photodegradation of polypropylene (PP) film was performed by a TiO₂/polyethylene oxide (PEO)/plant oil paint photocatalyst system. The photodegradation underwent two stages of development as follows: Initially PP reacted with linoleic acid radical originated from the photoreaction of plant oil component. Second, the linoleic acid graft‐polymer was decomposed, and then PP chain scission was caused. The process was studied using methyl linoleate (ML) in detail. The melting point of the 24 h‐photodegraded PP slightly decreased, and those of the 48 h‐ and 96 h‐ones drastically did as compared with the pristine PP. The crystallinity (χ_c) decreased at the 48 h photodegradation time and drastically increased at the 96 h one. The 24 h‐photodegraded PP showed the 77% Young's modulus, 88% tensile strength, and 103% strain at break values to those of the pristine PP. The ML graft‐polymerization and decomposition brought about the PP plasticizing and chemi‐crystallization, causing the PP degradation. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39909.     

Perpendicular oriented cylinders via directional coalescence of spheres embedded in block copolymer films induced by solvent annealing

Polystyrene-b-poly(methyl acrylate) (PS-b-PMA) block copolymer with PS volume fraction of 25.2 vol% was synthesized by atom transfer radical polymerization. Non-pretreated silicon wafers were used as the substrates to prepare perpendicular oriented PS cylinders in PMA matrix via solvent annealing which could induce the transformation of spheres to vertically oriented and hexagonally packed cylinders. The spherical microdomains were formed after the evaporation of solvents from the solutions of the block copolymer in selective solvents mixed from methanol, acetone and dichloromethane. The thickness of films could be as thick as 1000 nm, which were much thicker than usual cases and the cylinders came from the directional coalescence of the spheres, thus any pre-treatments of the substrates were not required for perpendicular orientation. The structures were characterized by small angle X-ray scattering (SAXS), transmission electron microscope (TEM), atom force microscopy (AFM) and grazing incidence small angle X-ray scattering (GISAXS).     

The roles of the Trommsdorff–Norrish effect in phase separation of binary polymer mixtures induced by photopolymerization

Influence of the Trommsdorff–Norrish (T–N) effect on the phase separation of methyl methacrylate (MMA)/poly(ethyl acrylate) (PEA) mixtures undergoing photo-polymerization was examined by a combination of several experimental techniques. By FT-IR spectroscopy, it was found that the polymerization conversion explosively increases at the onset of this T–N effect. The characteristic irradiation time τ at which this effect occurs, strongly depends on the light intensity and gradually shifts to early time as the irradiation intensity increases. The shrinkage of the mixture observed in situ by laser-scanning confocal microscopy exhibits a transition at a particular irradiation time which is slightly longer than the characteristic time τ. By gel permeation chromatography (GPC), it was found that the molecular weight of the resulting PMMA was almost unchanged before τ and suddenly increases about an order of magnitude after the onset of the auto-acceleration effect. Finally, the characteristic length scales of the morphology also quickly increase with irradiation time and are eventually frozen by this T–N effect. These experimental results indicate that the Trommsdorff–Norrish effect plays an important role in the kinetic processes of polymerization-induced phase separation, suggesting an efficient tool to control the morphology of the polymerizing mixture.     

取代聚苯乙炔环状三聚体的合成

以对溴苯酚为原料,经四步反应合成一种取代苯乙炔单体4-乙炔基-(2,6)二羟甲基-1-十二烷基酚醚。利用手性的铑催化剂引发聚合,得到高分子量的螺旋聚合物,通过GPC和CD对分子量和螺旋结构进行表征。最后通过光环化反应高效合成了环状三聚体,并通过1HNMR和GPC确认其化合物结构。