Synthesis of a New Thiophene/Quinoxaline CT‐Type Copolymer with High Solubility and Its Basic Optical Properties

A new π‐conjugated charge‐transfer‐type copolymer of electron‐donating thiophene and electron‐accepting quinoxaline was prepared by organometallic polycondensation. The polymer was soluble in organic solvents such as tetrahydrofuran, and showed a UV‐vis peak at long wavelengths of 598 nm in chloroform and 629 nm in the film. Its film exhibited a χ⁽³⁾ peak in the resonance region with a χ⁽³⁾ value comparable to that of regioregular head‐to‐tail poly(3‐hexylthiophene‐2,5‐diyl).

     

Amperometric enzyme-modified electrodes based on tetrathiafulvalene derivatives for the determination of glucose

A number of tetrathiafulvalene (TTF) derivatives have been synthesized and tested as electron transfer mediators in glucose oxidase-based amperometric biosensors. Using cyclic voltammetry and stationary potential experiments, it is shown that several of these derivatives can effectively mediate electron transfer from the reduced flavin adenine dinucleotide redox centers of glucose oxidase to a conventional carbon paste electrode. An insoluble polymeric electron relay system, based on the covalent attachment of TTF moieties to a highly flexible siloxane polymer, is also shown to facilitate a flow of electrons from the enzyme to the electrode. The resulting glucose biosensors function efficiently over a clinically relevant range of glucose concentrations.     

Preparation and Application of a Chemical Probe for Identifying the Targets of the Marine Cyclic Peptide Kapakahine A

Marine organisms are a rich source of bioactive secondary metabolites. Although many marine natural products with bioactivities have been isolated, successful elucidation of their mechanisms of action remains limited. In this study, we prepared a probe molecule based on the marine cyclic peptide kapakahine A (1) by introducing a linker with an azide terminal group, which enables the introduction of fluorescent groups for the effective monitoring of subcellular localization, or coupling to affinity beads for the pull-down of target proteins. The results of LC/MS/MS measurements, ProteinPilot analysis, and Western blotting suggest that kapakahine A interacts with the mitochondrial inner membrane proteins PHB1, PHB2, and ANT2, which is consistent with the results of the subcellular localization analysis using a fluorescent probe.     

Deoxygenation of tertiary and secondary benzylic alcohols into alkanes with triethylsilane catalyzed by solid acid tin(IV) ion-exchanged montmorillonite

We discovered an efficient protocol for the conversion of tertiary and secondary benzylic alcohols into the corresponding alkanes in good to quantitative yields by employing tin(IV) ion-exchanged montmorillonite (Sn-Mont) as a solid acid catalyst and Et3SiH as the hydride source. The reaction is likely to proceed via the S_N1-type reaction mechanism, that is, the formation of carbenium ions, followed by the addition of a hydride from the silane. The work-up of the reaction only requires simple filtration of the solid acid without any neutralization of the acid catalyst.     

Muonic X-ray measurements on mixtures of CaO/MgO and Fe3O4/MnO

Journal of Radioanalytical and Nuclear Chemistry - Elemental analysis by measurement of muonic X-rays shows great potential for analyzing the elemental composition of a bulk material at a specific...     

Visualization of deflagration-to-detonation transitions in a channel with repeated obstacles using a hydrogen–oxygen mixture

The deflagration-to-detonation transition in a 100 mm square cross-section channel was investigated for a highly reactive stoichiometric hydrogen oxygen mixture at 70 kPa. Obstacles of 5 mm width and 5, 10, and 15 mm heights were equally spaced 60 mm apart at the bottom of the channel. The phenomenon was investigated primarily by time-resolved schlieren visualization from two orthogonal directions using a high-speed video camera. The detonation transition occurred over a remarkably short distance within only three or four repeated obstacles. The global flame speed just before the detonation transition was well below the sound speed of the combustion products and did not reach the sound speed of the initial unreacted gas for tests with an obstacle height of 5 and 10 mm. These results indicate that a detonation transition does not always require global flame acceleration beyond the speed of sound for highly reactive combustible mixtures. A possible mechanism for this detonation initiation was the mixing of the unreacted and reacted gas in the vicinity of the flame front convoluted by the vortex present behind each obstacle, and the formation of a hot spot by the shock wave. The final onset of the detonation originated from the unreacted gas pocket, which was surrounded by the obstacle downstream face and the channel wall.