Biocompatible hydrogels based on chitosan,cellulose/starch,PVA and PEDOT:PSS with high flexibility and high mechanical strength

Fabricating mechanically strong hydrogels that can withstand the conditions in internal tissues is a challenging task. We have designed hydrogels based on multicomponent systems by combining chitosan, starch/cellulose, PVA, and PEDOT:PSS via one-pot synthesis. The starch-based hydrogels were homogeneous, while the cellulose-based hydrogels showed the presence of cellulose micro- and nanofibers. The cellulose-based hydrogels demonstrated a swelling ratio between 121 and 156%, while the starch-based hydrogels showed higher values, from 234 to 280%. Tensile tests indicated that the presence of starch in the hydrogels provided high flexibility (strain at break?>?300%), while combination with cellulose led to the formation of stiffer hydrogels (elastic moduli 3.9–6.6 MPa). The ultimate tensile strength for both types of hydrogels was similar (2.8–3.9 MPa). The adhesion and growth of human osteoblast-like SAOS-2 cells was higher on hydrogels with cellulose than on hydrogels with starch, and was higher on hydrogels with PEDOT:PSS than on hydrogels without this polymer. The metabolic activity of cells cultivated for 3 days in the hydrogel infusions indicated that no acutely toxic compounds were released. This is promising for further possible applications of these hydrogels in tissue engineering or in wound dressings.

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3-羟基丙烯醛单键旋转异构光反应机理的从头算研究

应用从头算分子轨道法分别在RHF/6-31G**和UHF/6-31G**水平上对3腔┤┓肿拥幕?S0)和三重激发态(T1)单键旋转异构反应机理进行了研究,优化出反应物和产物在S0态和T1态的4种平衡态和过渡态的几何构型,通过振动分析得到的虚频和计算的内禀反应坐标对过渡态进行了确认,并得到了零点能,根据基态和激发态反应途径分析了光反应机理。计算结果表明,基态和激发态的3腔┤┓肿拥ゼ旃狗从ξ焕萁系停嘏湃菀追⑸永砺凵涎橹ち斯夥从κ笛橹屑钢忠旃固宓拇嬖凇?     

Healable dual organic–inorganic crosslinked sol–gel based polymers: Crosslinking density and tetrasulfide content effect

In this article, the first generation of healable sol–gel based polymers is reported. A dual organic–inorganic crosslinked network is developed containing non‐reversible crosslinks and reversible (tetrasulfide) groups. The designed polymer architecture allows thermally induced mesoscale flow leading to damage closure followed by interfacial strength restoration due to reformation of the reversible groups. While the reversible bonds are responsible for the flow and the interface restoration, the irreversible crosslinks control the required mechanical integrity during the healing process. The temperature dependent gap closure kinetics is strongly affected by the crosslinking density and tetrasulfide content. Raman spectroscopy is used to explain the gap closure kinetics in air and dry nitrogen. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1953–1961     

Enhanced reactivity and enantioselectivity in catalytic glyoxylate-ene reactions using chiral bis(oxazoline)–copper complex in an ionic liquid

An optimal hydrophobic ionic liquid was discovered as a solvent for highly enantioselective glyoxylate-ene reactions catalyzed by a chiral bis(oxazoline)–copper complex. The reactivity and stereoselectivity were highly dependent upon the property of the ionic liquids; reactions between olefins and ethyl glyoxylate in [Bmim]SbF₆ at ambient temperature provided remarkably enhanced reactivity and stereoselectivity, which greatly exceed those of the corresponding reactions in dichloromethane. Furthermore, the metal–ligand complex was readily recycled up to eight times while exhibiting no significant decrease in reaction efficiency.     

Moduli spaces of arrangements of 10 projective lines with quadruple points

We classify moduli spaces of arrangements of 10 lines with quadruple points. We show that moduli spaces of arrangements of 10 lines with quadruple points may consist of more than 2 disconnected components, namely 3 or 4 distinct points. We also present defining equations to those arrangements whose moduli spaces are still reducible after taking quotients of complex conjugations.     

Investigation of surface plasmon resonance using cylindrical dielectric-metal-dielectric (C-DMD) plasmonic configuration

In this paper we have proposed a technique based on image analysis of the surface plasmon excitation at the metal-dielectric interface of inside silver coated fused silica capillary glass tube. Chemical deposition technique has been used for the deposition of silver. Angular interrogation in Kretschmann-like configuration is realized by non-radial transverse illumination of this cylindrical dielectric-metal-dielectric (C-DMD) structure with a He–Ne laser source. Here the uniform film deposition of the inside surface of the capillary is not that crucial except within the transversely illuminated working area concerned. Moreover, the proposed technique has been validated experimentally for sensing different aqueous dielectric samples inserted inside the tube.     

Reversible fixation and release of carbon dioxide with a binary system consisting of polyethylene glycol and polystyrene‐bearing cyclic amidine pendant group

In this study, we investigated the CO₂‐capture/release behavior of the polystyrene‐bearing cyclic amidine pendant groups, which was synthesized via free radical polymerization of HCl salt of the corresponding styrene monomer followed by neutralization. For comparison, we also prepared the polystyrene bearing N‐formyl‐1,3‐propanediamine pendant groups through the hydrolysis of the cyclic amidine group by treatment with an alkaline solution. First, we examined the CO₂‐capture/release behaviors of the amidine and amine monomers in aqueous solution in terms of conductivity. The conductivity of a wet DMSO solution of the amidine monomer increased upon CO₂ bubbling at 25 °C and reached a stationary value of about 11 mS/m, which indicated the formation of the bicarbonate salt. Conversely, the conductivity decreased to its original value upon N₂ bubbling at 50 °C, reflecting the complete release of the trapped CO₂ molecules. Both solutions showed the changes in the conductivity with quick responses, and no appreciable difference was observed between them. We then investigated the CO₂‐capture/release behaviors of the amidine and amine polymers, by taking advantage of the binary system with polyethylene glycol, and found that the binary system with the amidine polymer captured and released CO₂ more efficiently than that with the amine polymer. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2025–2031     

Ion implanted species dependence in silicon oxidation

The effect on thermal oxidation of implantation of the alkali species Li, Na, K, Rb and Cs has been studied. A correlation is found with the atomic and ionic radii and atomic masses of the implanted species, the larger ions leading to greater oxidation. We propose that the implanted species may affect the oxide plasticity and that this may be the controlling factor which determines the degree of oxidation.