Dioxin-like and transthyretin-binding compounds in indoor dusts collected from Japan: average daily dose and possible implications for children

Many researchers are increasingly interested in human exposure to house dust containing household compounds such as polybrominated diphenylethers (PBDEs). Nevertheless, no investigations have addressed the endocrine-disrupting potencies of compounds contained in indoor dust. This study specifically addresses endocrine-disrupting potencies such as dioxin-like activity and human transthyretin (TTR)-binding potencies. Using in vitro bioassays, we investigated these activity levels in indoor dusts. We performed exposure assessments of active compounds that are contained in house dust for subsequent evaluation of house dusts' risks to humans. Dioxin-like and TTR-binding activities in sulfuric acid treatment extracts of house and office dust were investigated using Dioxin-Responsive Chemical-Activated LUciferase gene eXpression assay (DR-CALUX) and TTR-binding assay (in vitro competitive human TTR-binding assay). Dioxin-like activities in indoor dust were 38-1400 pg CALUX-TEQ (2,3,7,8-TCDD equivalent)/g (median 160 pg CALUX-TEQ/g) and TTR-binding potencies were 300-5000 pmol T4EQ (thyroxine (T4) equivalent)/g (median 1000 pmol T4EQ/g), which are higher values than those in other environmental samples, e.g., contaminated sediments. These exposure results suggest that children might be affected by both dioxin-like compounds and TTR-binding compounds via house dust. When the ingestion rate, CALUX-TEQ, and T4EQ for house dust are high, thyroid hormone homeostasis in children may be disrupted.     

Selection of acid tolerant bifidobacteria and evidence for a low-pH-inducible acid tolerance response in Bifidobacterium longum

Acidity is an environmental condition commonly encountered by lactic acid bacteria and bifidobacteria in the gastrointestinal tract and fermented foods. In the present study, 22 strains of Bifidobacterium were screened for acid tolerance in artificial gastric juice (AGJ, pH 3.0) and fermented milk. AGJ tolerance was found to be strain-specific, with a pronounced variation among the strains. Several strains with a high survival rate in AGJ that belonged to Bifid. longum, Bifid. breve and Bifid. adolescentis were selected. Among them, only strain BL1 of Bifid longum was found to possess a high survival rate in fermented milk during refrigerated storage. Strain BL1 exhibited a survival rate of more than 25% in AGJ at pH 3.0 for 2 h and maintained a viable cfu level of more than 10(8) per gram of product in fermented milk (pH 4.6) under refrigerated conditions for 2 weeks. The acid tolerance of strain BL1 was found to depend on the final growth pH (<4.5). Rapid loss of acid tolerance was observed when the cells were shifted from acid to neutral conditions by addition of NaOH. Strain BL1 cells were able to maintain much higher intracellular pH under acid conditions, in comparison with those of AGJ sensitive mutant (BL1-S) or cells that lost acid tolerance following pH shifting from acid to neutral conditions. These results suggested that a cytoplasmic pH homeostasis system may function in the acid tolerance response in this strain.     

Detection of tris(2,4-di-tert-butylphenyl)phosphite (Irgafos 168, antioxidant in plastics) and its oxide in commercial frozen vegetables

Two peaks, A and B, detected in chromatograms of commercial frozen vegetable extracts during analysis of organophosphorus pesticide residues by GC-FPD, were identified as tris(2,4-ditert-butylphenyl)phosphite (Irgafos 168) and Irgafos 168 oxide, respectively, from their mass spectra. Irgafos 168 is used as an antioxidant in plastics, and there has been no report of its detection in foods. We analyzed Irgafos 168 and its oxide in 38 samples of commercial frozen vegetables, and they were detected from 4 samples (0.02-0.80 microgram/g as total amount of Irgafos 168 and its oxide).     

A study of the photolightening mechanism of blond hair with visible and ultraviolet light

In this study the photolightening behavior of blond hair was investigated. The results demonstrated that visible (VIS) and ultraviolet (UV) light lighten blond hair through different mechanisms. VIS light was found to contribute much more to the lightening of blond hair than UV light, and acted directly, while UV light only lightened blond hair that had been washed following irradiation. VIS and UV light both, however, lightened to a similar degree isolated melanin granules and decomposed melanin granules that were exposed on a cross section of blond hair. These results indicate that melanin granules are equally sensitive to both forms of light while blond hair is most sensitive to VIS light. The results also indicate that hair tissues, excluding melanin granules, are damaged by UV light but not by VIS light. Based on these facts, the hypothetical lightening mechanism of UV light is assumed to be that UV light preferentially attacks and damages hair tissues rather than melanin granules. This occurs only after the hair is washed, as the washing process removes the melanin granules that effuse from loose hair fibers. In contrast, VIS light preferentially attacks and decomposes the melanin granules rather than other tissues, and also results in the lightening of blond hair but without the need for subsequent washing. We also found that while VIS light destroys the structure of isolated melanin granules, UV light does not act in a similar manner. Consequently, it is proven that VIS and UV light attack different sites of the melanin granule, even though the lightening rates from both light sources are similar.     

Towards implementation of floating cast method for growing large‐scale high‐quality multicrystalline silicon ingot using designed double crucibles

We report on our attempt to scale up the floating cast method to grow high‐quality multicrystalline silicon ingot using specially designed double crucibles. The cross section of the grown ingot showed the large crystal grain size originating from initially formed dendrite crystals around the top of the melt. By using double crucibles, the residual melt was spontaneously removed from the inner crucible to the outer one at the final stage of the crystal growth. Performance of small‐scale solar cells revealed no significant changes between the top and the bottom part of the ingot except the edge of the bottom due to the non‐uniform removal of the melt. This suggests that strong contact of the ingot with the crucible was successfully avoided by the double crucibles. Therefore, the floating cast method combined with specially designed double crucibles is concluded to be feasible, which could be implemented to realize high‐quality multicrystalline silicon ingot for practical size wafers. Copyright © 2013 John Wiley & Sons, Ltd.     

Material design using genetic algorithms and preparation of innovative UV-reflecting composite

The neck is a sun-exposed area. It seems to show the symptoms of photo-ageing as well as facial skin in the elderly. However, the physiological study of neck skin has hardly been reported. We examined the change of skin physiological properties at a neck site with ageing for 61 women (18—69 years old) compared with a cheek site. Water content in stratum corneum (SC) was higher, transepidermal water loss (TEWL) was lower and the turnover rate of SC judged from corneocyte area was slower at the neck site compared with the cheek site. Skin thickness was thinner, skin extensibility and elasticity were higher, skin grooves were deeper, and anisotropy of skin furrows was lower at the neck site than those at the cheek site. It was shown that the neck was also affected by sunlight but not so much as the cheek from the result of gelatinase activity detected in the tape stripped SC. Skin elasticity decreased with ageing at the neck site as well as the cheek site. Fine wrinkles were remarkably increased in the direction of Langer's line with ageing at the neck. Most skin physiological parameters at the neck showed the value between the cheek (heavily sun-exposed area) and back (not sun-exposed area). From these results, it was considered that not only intrinsic ageing but also photo-ageing affected the neck skin. We developed the prototype of cosmetics corresponding to neck skin physiology based on these results, and evaluated the effectiveness of the prototype product by a consumer test including skin measurement for 4 weeks. After treatment, water content increased, and it gave satisfaction in the skin colour brightness, skin elasticity and skin texture improvements for almost all volunteers. It was concluded that the prototype product was useful in neck skin treatment.     

Preparation of TiO2 thin films using octadecylamine Langmuir-Blodgett films and evaluation of their photocatalytic activity

A study was conducted to demonstrate that nanometer-thick titanium dioxide (TiO(2)) thin films could be prepared by the hydrolysis of titanium potassium oxalate using octadecylamine (ODA) Langmuir-Blodgett (LB) films as templates. The amount of TiO(2) generated in the LB film was found to be proportional to the number of deposited ODA layers, which enables precise control of the TiO(2) film thickness. After heat treatment of the LB films at 300-600°C, the photocatalytic activities of the resulting TiO(2) films were determined from the decomposition of stearic acid cast films when irradiated with UV light for different time periods. Higher photocatalytic activity was observed in TiO(2) films heat treated at lower temperatures.