A hydrogel with rubber elasticity transition

Reaction between dimethyldivinylsilane and 3,6-diazaoctane in the presence of 3-lithio-3,6-diazaoctane yields a new telechelic oligomer, poly(silamine), which consists of alternating 3,3-dimethyl-3-silapentane and N,N′-diethylethylenediamine units in the main chain. Poly(silamine) shows unique phase transition properties in response to the degree of protonation of amino groups in the polymer. Poly(silamine) also shows a strong interaction with several anions. Due to the interaction between poly(silamine) and anions along with the protonation of amino groups in the poly(silamine), the rubber elasticity of poly(silamine) is drastically changed. A discrete volume change can be observed when the environmental pH of the poly(silamine) gels is varied. This can be explained not only by a change in ionic osmotic pressure but also by a change in the rubber elasticity of the networks in the gel.     

Fragmentation of the metastable molecular ion of methyl lactate: The formation of oxygen-protonated methanol [CH3OH2]+ involving double hydrogen atom transfers

The spontaneous unimolecular dissociation reaction of methyl lactate (1) ionized by electron impact was investigated by a combination of mass-analyzed ion kinetic energy spectrometry and deuterium labeling. The metastable ions 1^+· decompose in a variety of ways: four fragment peaks are observed at m/z 89, 76, 61, and 45, which correspond to the losses of ?H₃, CO, CH₃?O, and ?OOCH₃, respectively. Double hydrogen atom transfer occurs in the third reaction. The source-generated m/z 61 ions decompose into oxygen-protonated methanols at m/z 33 ([CH₃OH ₂ ⁺ ]) by the loss of CO with double hydrogen atom migration. Both hydroxyl and methyne hydrogen atoms in 1 ^+· are present in the resultant protonated methanols.     

Quasi-variational inequalities, generalized Nash equilibria, and multi-leader-follower games

In Pang and Fukushima (Comput Manage Sci 2:21–56, 2005), a sequential penalty approach was presented for a quasi-variational inequality (QVI) with particular application to the generalized Nash game. To test the computational performance of the penalty method, numerical results were reported with an example from a multi-leader-follower game in an electric power market. However, due to an inverted sign in the penalty term in the example and some missing terms in the derivatives of the firms’ Lagrangian functions, the reported numerical results in Pang and Fukushima (Comput Manage Sci 2:21–56, 2005) are incorrect. Since the numerical examples of this kind are scarce in the literature and this particular example may be useful in the future research, we report the corrected results. The online version of the original article can be found under doi:.     

Effect of melt viscosity and surface tension of polymers on the percolation threshold of conductive-particle-filled polymeric composites

The electrical conductivities of carbon-black-filled low-density polyethylene (LDPE), poly(methyl methacrylate) (PMMA), and poly(vinyl chloride)-vinyl acetate (PVC/ VAc) copolymer were measured as functions of carbon content and melt viscosity of the matrix at the temperatures at which the composites were prepared. Sharp breaks in the relationship between the carbon filler content and the conductivity of composites were observed in all specimens at some content of the carbon filler. The conductivity jumps as much as 10 orders of magnitude at the break point. This phenomenon has been known as the “percolation threshold”. The critical carbon content corresponding to the break point     

Manganese(III)-Catalysed Oxidation of Sulphides with Sodium Chlorite in an Aprotic Solvent in the Presence of Alumina

A wide variety of sulphides can be readily converted to the corresponding sulphoxides in good to excellent yields by treatment with a combination of sodium chlorite, (salen)manganese(III) complex, and chromatographic alumina in dichloromethane under mild and neutral conditions.     

The effect of various calcination treatments on the photocatalytic activity of a rod-type TiO<Subscript>2</Subscript> electrode for oxidation of ethanethiol

It was found that the photoelectrochemical performance and photocatalytic activity of rod-type TiO₂ electrodes were affected by various post-calcination treatments, for example, calcination in NH₃ or under vacuum. Post-calcination treatment in NH₃ at 773 K was particularly effective in increasing the photoelectrochemical performance and photocatalytic activity of rod-type TiO₂ electrodes. A unique photoelectrochemical circuit was constructed by connecting a rod-type TiO₂ electrode to a Pt electrode through a silicon solar cell in which the negative bias was applied on the rod-type TiO₂ electrode. It was found that the photoelectrochemical circuit can effectively oxidize ethanethiol in water into CO₂.     

A practical synthesis of L-ribose

L-Ribose was synthesized by a simple four-step method with overall yield of 76.3% from a protected L-arabinose derivative, which is a compatible intermediate for the synthesis of L-deoxyribose. The key step of this strategy is the Swern oxidation and subsequent stereoselective reduction accompanied by inversion of the 2-hydroxy group of protected L-arabinose.     

Amphotericin B dimers with bisamide linkage bearing powerful membrane-permeabilizing activity

[structure: see text] Covalently linked dimers of amphotericin B were prepared by cross-linking its carboxylic acid. Among these, a dimer with a linkage of 1,6-hexanediamine revealed potent hemolytic activity (EC50, 0.25 microM) while its N-acetyl derivative gave rise to large K+ ion flux in phosphatidylcholine liposomes, regardless of the presence or absence of sterols, suggesting that the dimers may serve as a tool for elucidating the structure of the ion channel assemblage formed by amphotericin B.