Catalytic Use of a Soluble Organoindium(III) Species for Allylation and Crotylation of Ketones with Boronates

The unprecedented use of a soluble organoindium species, indium(III) hexamethyldisilazide [In(III)(hmds)₃], for catalytic carbon carbon bond formations between ketones and boronates, is reported. Various functionalized tertiary homoallyl alcohols were generated easily in high yields. Remarkably, free hydroxy and primary amine functionalities proved to be tolerated. A rate acceleration and markedly improved diastereoselectivities were observed in the presence of methanol. Based on preliminary NMR experiments and the α‐selectivity with an α‐substituted boronate, we assume the in situ generation of reactive allylindium(III) species through catalytic boron‐to‐indium transmetalation.     

Studies on antimutagenic effect of milk cultured with lactic acid bacteria on the Trp-P2-induced mutagenicity to TA98 strain of Salmonella typhimurium.

The inhibitory effects of cultured milk using 76 strains of lactic acid bacteria isolated from milk products were investigated on the mutagenicity of 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P2), a tryptophan pyrolysate for Salmonella typhimurium TA98. Each cultured milk sample displayed its characteristic antimutagenic effect against the mutagenicity of Trp-P2. The milk cultured with Lactobacillus acidophilus LA106 (LA2) showed the highest inhibition of 82.1% among the strains used. Milk samples cultured with Lactococcus lactis subsp. lactis, Lll103 (10-3) and Lll102 (KM) also exhibited higher inhibition percentages.     

Development of a strain for efficient degradation of polychlorinated biphenyls by patchwork assembly of degradation pathways

Rhodococcus jostii RHA1 accumulates chlorobenzoates (CBA) during the degradation of polychlorinated biphenyls (PCBs). CBA degradation is considered one of the rate-limiting steps in the complete degradation of PCBs. To reduce the accumulation of CBAs, the upper pathway enzyme genes for PCB degradation of RHA1 were introduced into a CBA-degrading bacterium, Burkholderia sp. NK8. The resulting recombinant strain exhibited no biphenyl 2,3-dioxygenase (BphA) activity encoded by bphAaAbAcAd genes, which encode the large and small subunits of the terminal oxygenase component and the ferredoxin and reductase subunits responsible for electron transfer from NADH to the large subunit. The remaining enzyme genes involved in the transformation of biphenyl to benzoate, bphB2C1D1, which encode dehydrogenase, ring-cleavage dioxygenase and hydrolase, conferred activities to NK8. To obtain the BphA activity of RHA1 in NK8, sets of BphA genes were constructed by combining the bphAaAbAcAd genes of RHA1 and bphA3A4 of Pseudomonas pseudoalcaligenes KF707, encoding the ferredoxin and reductase subunits. Hybrid derivatives of BphA containing the KF707 bphA3 conferred BphA activity to NK8, and a derivative containing the RHA1 bphAaAb and KF707 bphA3A4 genes exhibited the highest BphA activity. A plasmid containing the RHA1 bphAaAb and KF707 bphA3A4 genes plus the RHA1 bphB2C1D1 genes was constructed and introduced into NK8. The resulting recombinant strain efficiently degraded 2-, 3- and 4-chlorobiphenyls with an apparent reduction in CBA accumulation in comparison to the recombinant mutant strain, which had an insertion in the cbeA gene to inactivate CBA dioxygenase.     

Antibacterial activity of Bacillus amyloliquefaciens phage endolysin without holin conjugation

To characterize the enzymatic activity and antibacterial activity of endolysin encoded by a Bacillus amyloliquefaciens phage, the open reading frame encoding endolysin was amplified by PCR and cloned into the expression plasmid pET21d(+). The resultant plasmid was used to transform Escherichia coli JM109(DE3). Production of endolysin in the cytosol facilitated cell lysis without coproduction of holin, which is considered to degrade or alter the cytoplasmic membrane. The phage endolysin was overexpressed and purified. Although the specific activity of the purified phage endolysin towards lyophilized Micrococcus luteus cells was 1/11 of the activity of chicken egg white lysozymes, the endolysin showed stronger antibacterial activity towards E. coli W3110, E. coli JM109(DE3) and Pseudomonas aeruginosa PAO1 than chicken egg white lysozymes. The antibacterial activity of the endolysin towards these three bacterial strains was marked when EDTA was added to the endolysin solution.     

Response speed and optical investigation of inGaN/gaN multiple quantum well light‐emitting diodes (LED)

Transmission experiments for a local area network (LAN) using blue‐light‐emitting diodes (LEDs) with InGaN/GaN multiple quantum well (MQW) and plastic optical fibers (POFs) have been conducted. Audio analog signals have been transmitted up to 1800 kHz, which corresponds to an optical 1.5 dB bandwidth of LED response. The response speed of these diodes has been investigated by varying the operating conditions: dc bias, pulse amplitude, and pulse shape. The LED rise time is reduced from 0.26 μs to 0.19 μs by changing the electrical pulse amplitude from 0.5 V to 1.2 V, whereas the fall time (0.20 μs) does not change. On the other hand, the fall time is reduced from 0.20 μs to 0.14 μs by adding negative pulses after the applied positive pulses. It is shown that the direct‐modulation speed of these diodes is limited by the time constant associated with device capacitance. Electroluminescence and photocurrent spectra of the LEDs were also investigated; blueshifts were observed for both peaks in the spectra. © 2001 Scripta Technica, Electr Eng Jpn, 137(3): 47–51, 2001     

Epoxy curing reaction studied by using two‐dimensional correlation infrared and near‐infrared spectroscopy

The isothermal curing process of bisphenol A epoxy resin with polyamine reagent (1,6‐diaminohexane) was monitored in situ by using temperature‐controlled Fourier‐transform infrared (FTIR) and Fourier‐transform near infrared (FTNIR) spectroscopy to elucidate the relative changes in functional groups during the curing reaction. It was shown that generalized two‐dimensional correlation spectroscopy can provide new information about the mechanisms and kinetics of the curing process, and the band assignments for complex NIR spectrum associated with this system. The sequential order of relative changes in functional groups during the curing process was examined by generalized 2D correlation spectroscopy and NIR‐IR hetero‐correlation spectroscopy, and the details of the complex epoxy curing reaction involving both primary and secondary amino group were revealed. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effects of heating rate on microstructure and transparency of spark-plasma-sintered alumina

Commercial alumina powder was densified by spark plasma sintering (SPS) at 1150 °C. During SPS processing, the effects of the heating rate were examined on microstructure and transparency. With decreasing heating rate, the grain size and the residual porosity decreased, while the transparency increased. At a heating rate of 2 °C/min, the grain size was 0.29 μm, and the in-line transmission was 46% for a wavelength of 640 nm. The mechanisms for the fine microstructure and low porosity at slow heating, which are conflicting with some existing results, were explained by considering the role of defect concentration and grain-boundary diffusion during densification.