Metal-Containing initiator Systems. XXXVI. Synthesis of Block Copolymer of Methyl Acrylate and α-Methylbenzyl Methacrylate with Binary Initiator System of Cobaltocene and Bis(ethyl acetoacetato)copper(II)

Polymerizations of methyl acrylate (MA) and (DL)-α-methyl-benzyl methacrylate (MBMA) with binary initiator system of cobaltocene [Co(C₅H₅)₂] and bis(ethyl acetoacetato)copper(II) [Cu(eacac)₂] were studied in acetonitrile at 25°C. The molecular weight of the polymers obtained by MA was found to increase with time in the early stage of polymerization. Although MBMA was also polymerized by this system, asymmetric selective polymerization was not induced in the presence of (-)-sparteine. The synthesis of the block copolymer of MA and MBMA was attempted by using this initiator system. The block copolymer was obtained in 90% yield in the polymerization of MBMA with a polymer radical which prepared from MA with this system for 1 day. The yield of the block copolymer depended on the prepolymeriza-tion time of MA by this system. The resulting block copolymer was characterized by IR, ¹H-NMR, and gel-permeation chromatography.     

Stress relaxation of GaN microstructures on a graphene‐buffered Al2O3 substrate

GaN microstructures were grown on c‐Al₂O₃ with a multi‐stacked graphene buffered layer using metal metal‐organic chemical‐vapor deposition. Under the same growth conditions, the nucleation of GaN was suppressed by the low surface energy of graphene, resulting in a much lower density of microstructures relative to those grown on c‐Al₂O₃. Residual stress in the GaN microstructures was estimated from the peak shift of the E₂ phonon using micro‐Raman spectroscopy. The results showed that the compressive stress of approximately 0.36 GPa in GaN on c‐Al₂O₃ caused by lattice mismatch and the difference in the thermal expansion coefficient was relaxed by introducing the graphene layer. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Colorimetric detection of PCR products of DNA from pathogenic bacterial targets based on a simultaneously amplified DNAzyme

A novel strategy was devised for colorimetric analysis of the products of the polymerase chain reaction (PCR). The method takes advantage of simultaneous amplification of a horseradish peroxidase-mimicking DNAzyme (HRPzyme) during the PCR process. It is performed using a DNA specific forward primer and a universal reverse primer containing a complementary HRPzyme sequence. The double-strand PCR products, which include the HRPzyme sequence, are treated with a mixture of hemin and TMB (3,3′,5,5′–tetramethylbenzidine) in the presence of hydrogen peroxide. The resulting HRPzyme/hemin complex then promotes a peroxidase mimicking reaction, which produces the blue colored oxidized TMB. This colorimetric method can be more easily performed than previously developed gel based detection procedures and, as a result, can be conveniently applied to the specific and sensitive colorimetric analysis of DNA sequences arising from pathogenic bacteria. The potentially broad applicability of the new method has been demonstrated by its use in the identification of the 16s rDNA of Salmonella Typhimurium.

A novel strategy was devised for simple colorimetric analysis of PCR products with amplification of a horseradish peroxidase-mimicking DNAzyme(HRPzyme). This colorimetric method can be much more easily performed than previously developed gel based detection procedures and potentially broad applicability for other DNA analysis.

     

Reduction Characteristics of Carbon Dioxide Using a Plasmatron

To decompose carbon dioxide, which is a representative greenhouse gas, a 3-phase gliding arc plasmatron device was designed and manufactured to examine the decomposition of CO₂, either alone or in the presence of methane with and without water vapour. The changes in the amount of carbon dioxide feed rate, the methane to carbon dioxide ratio, the steam to carbon dioxide ratio, and the methane to steam ratio were used as the parameters. The carbon dioxide conversion rate, energy decomposition efficiency (EDE), carbon monoxide and hydrogen selectivity, and produced gas concentration were also investigated. The maximum values of the carbon dioxide conversion rate, which is a key indicator of carbon dioxide decomposition, in different cases were compared. The maximum carbon dioxide conversion rate was 12.3 % when pure carbon dioxide was supplied; 34.5 % when methane was injected as a reforming additive; 7.8 % when steam was injected as a reforming additive; and 43 % when methane and steam were injected together. Therefore, this could be explained that the methane-and-steam injection showed the highest carbon dioxide decomposition, showing low EDE as 0.01 L/min W. Furthermore, the plasma produced carbon-black was compared with commercial carbon-black chemicals through Raman spectroscopy, surface area measurement and scanning electron microscopy. It was found that the carbon-black that was produced in this study has the high conductivity and large specific surface area. Our product makes it suitable for special electric materials and secondary battery materials applications.     

Experimental evaluation of the effect of a modified port‐location mode on the performance of a three‐zone simulated moving‐bed process for the separation of valine and isoleucine

The removal of isoleucine from valine has been a key issue in the stage of valine crystallization, which is the final step in the valine production process in industry. To address this issue, a three‐zone simulated moving‐bed (SMB) process for the separation of valine and isoleucine has been developed previously. However, the previous process, which was based on a classical port‐location mode, had some limitations in throughput and valine product concentration. In this study, a three‐zone SMB process based on a modified port‐location mode was applied to the separation of valine and isoleucine for the purpose of making a marked improvement in throughput and valine product concentration. Computer simulations and a lab‐scale process experiment showed that the modified three‐zone SMB for valine separation led to >65% higher throughput and >160% higher valine concentration compared to the previous three‐zone SMB for the same separation.     

l-Proline-derived ligands to mimic the ‘2-His-1-carboxylate’ triad of the non-haem iron oxidase active site

Non-haem iron(II) oxidases (NHIOs) catalyse a variety of oxidative transformations in biology. The iron-binding environment of the NHIO active site typically incorporates a ‘2-His-1-carboxylate’ facial triad of amino acid side-chains, a motif that has emerged as a defining feature of the enzyme family. Towards the goal of biomimetic, iron-mediated C–H activation we have synthesized a series of peptidomimetic ligands from l-proline. By coupling l-proline to 2,6-bis(bromomethyl)pyridine, 2-(bromomethyl)-6-((tert-butyldimethylsilyloxy)methyl)pyridine and picolinic acid, we have generated several new ligand architectures designed to complex with iron(II) and mimic the NHIO active site. The resulting iron complexes promote modest levels of alkene dihydroxylation and allylic oxidation using hydrogen peroxide as oxidant.     

Influence of N-doping on the structure and electronic properties of titania nanoparticle photocatalysts

N-containing TiO(2)-based nanostructured materials (average particle size approximately 10 nm) with an anatase-type structure were investigated using oxygen (O) K-edge and titanium (Ti) K- and L-edge X-ray absorption near-edge spectroscopy (XANES). The Ti K pre-edge features indicate that samples predominantly contain ([6])Ti with some ([5])Ti, and there is no evidence for ([4])Ti. We observed that those samples with a larger fraction of Ti in a fivefold coordination, that is, with a significant number of oxygen vacancies, also present a modified Ti environment at the medium-range scale. The presence of these defects drastically modifies the electronic structure of the conduction band, as evidenced by the O K XANES spectra, but does not result in the presence of reduced Ti(3+) states. We discuss the influence of N-doping on titania nanoparticles and their structure, electronics and photocatalytic activity.