Purification and some properties of cholesterol oxidase stable in detergents from gamma-proteobacterium Y-134

Cholesterol oxidase (CHO) with high stability in detergents was found from an isolated strain, Y-134, belonging to the gamma-subclass of Proteobacteria. CHO production reached its maximum by incubation at 30 degrees C for 12 d. It was purified from cell-free extract prepared by mixing the cells with 0.4% Triton X-100. The absorption spectrum of the purified enzyme exhibited maxima at 274 and 410 nm, and a shoulder at 330 nm. The molecular mass was 115 kDa with two identical subunits of 58 kDa. The enzyme oxidized cholest-5-en-3beta-ol (cholesterol) and 5alpha-cholestan-3beta-ol (dihydrocholesterol) at a high reaction rate, and the K(m) value for cholesterol was 65 microM. The stability of the enzyme was higher than other CHOs in nonionic detergents with high values of hydrophilelipophile balance (HLB) such as Triton X-450 and sodium cholate. NH2-terminal sequence analysis showed a high similarity to CHO from Burkholderia cepacia, but not to CHOs from Streptomyces or Brevibacterium.     

Determination of alkylphenols,bisphenol A,benzophenone and phthalates in containers of baby food,and migration into food simulants

Infants, whose growth and development are highly dependent upon the endocrine system, are particularly vulnerable to endocrine disruptor exposure. In our study, we examined whether or not alkylphenols, bisphenol A, benzophenone, di(2-ethylhexyl)adipate and 10 phthalates are present in containers of baby food. Furthermore, the migration into food-simulating solvents was also examined. Sixteen types of containers of baby food, obtained on the Japanese market in 2001, were examined: 8 glass bottle types, 1 plastic type, 1 metallic package (laminated with plastic) and 6 multilayered laminated film packages. Alkylphenols, benzophenone, bisphenol A and di(2-ethylhexyl)adipate were not detected in any of the samples. On the other hand, dibutylphthalate (DBP) was detected in 7 samples (1.2-9.1 micrograms/sample), and di(2-ethylhexyl)phthalate (DEHP) was detected in 15 samples (1.3-18 micrograms/sample). Migration tests were carried out for 5 samples, and the levels of DBP and DEHP that migrated into n-heptane were 0.68-1.7 micrograms/sample and 0.33-3.5 micrograms/sample, respectively. From these results, a baby's intake levels of DBP and DEHP were estimated to be about 1/2,500 and 1/90-300 of the tolerable daily intake (TDI), respectively.     

Estimation of daily intake of phenols in hospital meal samples

Daily intakes of 12 phenols which are possible endocrine disruptors were estimated in hospital meals from 2000 to 2001. 4-Nonylphenol (4-NP (mix)) and bisphenol A (BPA) were detected at levels of 5.0 to 19.4 ng/g and 0.2 to 1.1 ng/g, respectively. 4-tert-Butylphenol, 4-n-pentylphenol, 4 -tert-pentylphenol, 4-n-hexylphenol, 4-n-heptylphenol and 4-tert-octylphenol were detected at levels of 0.1 to 2.4 microg/g. The daily intakes of 4-NP (mix) and BPA were 5.8 microg/day and 0.42 microg/day, respectively. The daily intakes of other phenols were less than 1 microg/day.     

Visible-light photocatalytic activity of TiO2−x by heat treatment and plasma-heat treatment

The partial reduction of TiO₂ was attempted by heat treatment and plasma-heat treatment and it was carried out to investigate the photocatalytic characteristics of partially reduced TiO₂ (TiO_2?x) in the visible-light region. As a result, the plasma-heat treatment shows significantly stronger than the heat treatment for the visible-light photocatalytic activity of TiO₂. The red-shifted absorption bands in the visible-light region of TiO_2?x by plasma-heat treatment gave broader than one by heat treatment. The TiO_2?x by heat treatment and plasma-heat treatment was changed white to beige color, and white to navy, respectively.     

Automated single nucleotide polymorphism typing using bead array in capillary tube

A low-cost and simple on-site technique for genotyping single nucleotide polymorphisms (SNPs) was developed. The technique is based on allele-specific primer PCR and the recently developed bead arrays in a single tip technique. The performance of the method was verified by genotyping four SNPs that correlate with cardiovascular diseases.     

Interaction of π-bonds of the silicon–silicon triple bond with alkali metals: An isolable anion radical upon reduction of a disilyne

The reduction of 1,1,4,4-tetrakis[bis(trimethylsilyl)methyl]-1,4-diisopropyltetrasila-2-yne 1 with an equivalent amount of alkali metal (Li, Na, K, KC₈) in THF produced the corresponding disilyne anion radicals 2a–c. Their EPR spectra are independent of the metals used in THF, indicating that the disilyne anion radical species exists as solvent-separated ion pairs in polar solvents. The one-electron reduction also occurred with potassium in toluene to produce the potassium salt of the anion radical 3, which was isolated as extremely air- and moisture-sensitive dark brown crystals. The molecular structure of 3 was established by X-ray crystallography, which showed that the potassium ion is solvated by one toluene molecule. The EPR spectrum of 3 in toluene showed the interaction of the anionic silicon atom with the K⁺ ion.     

Control of carbon incorporation in AlAs grown by atomic layer epitaxy using variously orientated substrates

We demonstrate a method for successfully controlling carbon incorporation in AlAs layers grown by atomic layer epitaxy (ALE) using various GaAs substrates with different orientations. The number of alkyl radicals attached to an Al atom at the surface, which is a main factor in carbon incorporation, can be intentionally controlled by changing substrate orientation. We found that the carbon incorporation in ALE-AlAs using the (3 1 1)B surface is 2 x 10¹⁷,cm^-3, which is the lowest value ever reported for ALE-AlAs that satisfies one-monolayer self-limiting growth conditions.     

Pb-free surface-finishing on electronic components’ terminals for Pb-free soldering assembly

Pb-free solderable surface finishing is essential to implement Pb-free solder assembly in order to meet with the growing demand of environmental consciousness to eliminate Pb from electronic products. Two types of widely applicable Pb-free surface finishing technologies are developed. One is the multilayer-system including Pd with Ni undercoat. Heat-resistance of Pd enables whole-surface-plating on to leadframe before IC-assembling process. The other is the double-layer-system with low-melting-point-materials, for example, thicker Sn underlayer and thinner Sn-Bi alloy overlayer, dilutes Sn-Bi alloy’s defects of harmful reactivity along with substrate metal and mechanical brittleness with keeping its advantages of solder-wettability and no whisker.     

Bulk heterojunction organic solar cells utilizing 1,4,8,11,15,18,22,25-octahexylphthalocyanine

Bulk heterojunction solar cells utilizing soluble phthalocyanine derivative, 1,4,8,11,15,18,22,25-octahexylphthalocyanine (C6PcH₂) have been investigated. The active layer was fabricated by spin-coating the mixed solution of C6PcH₂ and 1-(3-methoxy-carbonyl)-propyl-1-1-phenyl-(6,6)C61 (PCBM). The photovoltaic properties of the solar cell with bulk heterojunction of C6PcH₂ and PCBM demonstrated the strong dependence of active layer thickness, and the optimized active layer thickness was clarified to be 120 nm. By inserting MoO₃ hole transport buffer layer between the positive electrode and active layer, the FF and energy conversion efficiency were improved to be 0.50 and 3.2%, respectively. The tandem organic thin-film solar cell has also been studied by utilizing active layer materials of C6PcH₂ and poly(3-hexylthiophene) and the interlayer of LiF/Al/MoO₃ structure, and a high V_oc of 1.27 V has been achieved.