Modeling the effect of oxygen on vapor phase diamond deposition inside micro-trenches

For the same feed gas composition, radical species concentrations vary with depth inside micro-trenches during diamond deposition. However, the feed gas compositions are typically used for predicting diamond deposition vs. non-diamond deposition. So, any type of modeling for predicting diamond deposition quality and uniformity inside trenches and onto three-dimensional objects is not possible. In this regard, a simple modeling approach utilizing a recently constructed C–H–O ternary diagram, based on radical species composition by Eaton and Sunkara [Eaton and Sunkara, Diam. Relat. Mater., 9 (2000) 1320], demonstrated the diamond deposition process inside trenches. Specifically, the effect of oxygen in the feed gases on the depths at which diamond can be deposited is modeled under both Knudsen and Fickian diffusion conditions and compared with experimental observations. The results suggested that certain feed gas phase compositions (C/O ratio) help increase the aspect ratio (>2.0) at which diamond deposition can be achieved.     

Effects of processing and cooking on the levels of pesticide residues in wheat samples

The effects of processing and cooking on the levels of pesticide residues in wheat samples were investigated for 13 pesticides in pre-harvest (Pre, 9 pesticides) and post-harvest (Post, 6 pesticides) samples. In the milling process, the transfer ratios (%, total pesticide residue amount in product/that in wheat grain) of wheat bran were greater than 70% and 80% for pre-harvest and post-harvest samples, respectively. The transfer ratios of flour ranged from 1.7% to 23% (Pre) and 4.0% to 11% (Post). There was no significant difference in transfer ratio among the pesticides investigated. The processing factors (Pf, the concentration (mg/kg) of pesticide in product/that in the wheat grain) of flour ranged from 0.030 to 0.40 (Pre) and 0.069 to 0.18 (Post). The values in pre-harvest samples were higher than those in post-harvest samples. Investigation of changes of pesticide residues during processing and/or cooking is useful not only to establish MRLs, but also to recognize actual levels of pesticide residues in food.     

Effects of processing and cooking on the levels of pesticide residues in rice samples

The effects of processing and cooking on the levels of pesticide residues in rice samples were investigated for 11 pesticides in pre-harvest (9 pesticides) and post-harvest (4 pesticides) samples. In the polishing process, the transfer ratio (%, total pesticide residue amount in product/that in brown rice) of rice bran ranged from 40% to 106%, and the transfer ratio of polished rice ranged from 9% to 65% in pre-harvest samples. These values varied from pesticide to pesticide. The processing factor (the concentration (mg/kg) of pesticide in product/that in the brown rice) of polished rice ranged from 0.11 to 0.73. The loss of pesticides during processing and/or cooking did not correlate to any single physical or chemical property. Investigation of changes of pesticide residues during processing and/or cooking is useful not only to establish MRLs, but also to recognize actual levels of pesticide residues in food.     

Use of single-strand conformation polymorphism of amplified 16S rDNA for grouping of bacteria isolated from foods

The grouping method for isolated strains from foods using single-strand conformation polymorphism (SSCP) after PCR amplification of a portion of 16S rDNA was developed. This method was able to group the strains from various food samples based on 16S rDNA sequence. As 97.8% of the isolated strains from various foods were grouped correctly, use of the PCR-SSCP method enables the prompt and labor-saving analysis of microbial population of food-derived bacterial strains. Advantages in speed and accuracy of bacterial population identification by the PCR-SSCP method have practical application for food suppliers and testing laboratories.     

Hijiki seaweed consumption elevates levels of inorganic arsenic intake in Japanese children and pregnant women

Although exposure to inorganic arsenic is a health concern, especially in developing foetuses and children, dietary exposure levels among pregnant women and children have not been extensively studied in Japan. To address this shortcoming, we completed a 3-day duplicate diet study for 104 children and 101 pregnant women in two cities, Shimotsuke, Tochigi and Asahikawa, Hokkaido. The levels of intake of total and inorganic arsenic were estimated using the concentrations of total and inorganic arsenic in food and drinking water measured by inductively coupled plasma-mass spectrometry. Estimated intakes of total and inorganic arsenic were 8.46 ± 3.02 [µg/kg BW/week] and 1.74 ± 1.07 [µg/kg BW/week] in pregnant women and 20.07 ± 3.53 [µg/kg BW/week] and 8.46 ± 3.02 [µg/kg BW/week] in children, respectively. Weekly arsenic exposure per kg body weight was significantly higher in children than in pregnant women. Concentrations of total arsenic were generally very low in collected drinking water samples with a small number of exceptions, and drinking water was not considered as a major source of inorganic arsenic exposure in Japan. We found that total and inorganic arsenic intake were higher among frequent consumers of hijiki seaweed, in both pregnant women and children. Although rice and rice products that are staple foods of the Japanese have been reported to be major sources of inorganic arsenic exposure in Japan, our results indicate that hijiki consumption elevates levels of inorganic arsenic in Japanese children and pregnant women. More efforts are necessary to reduce the risk of exposure to inorganic arsenic in populations highly sensitive to environmental pollutants.     

Overexpression of 1-Deoxy-D-xylulose-5-phosphate reductoisomerase gene in chloroplast contributes to increment of isoprenoid production

Plants synthesize a large number of isoprenoid compounds that are of industrial, nutritional and medicinal importance. 1-Deoxy-D-xylulose reductoisomerase (DXR) catalyzes the first committed step of plastidial isoprenoid-precursor biosynthesis. In the present study, we generated transplastomic tobacco plants that overproduced DXR from Synechosystis sp. strain PCC6803. The transformants showed increase in the content of various isoprenoids such as chlorophyll a, beta-carotene, lutein, antheraxanthin, solanesol and beta-sitosterol, indicating that the DXR reaction is one of the key steps controlling isoprenoid level in tobacco leaves. A qualitative change in isoprenoid composition was also observed. The growth phenotype of the transplastomic plants was similar to that of wild-type plants. These results showed that plastid metabolic engineering is useful in manipulating the yield of isoprenoids in plants.     

Loading and release of methyl orange in layer-by-layer assembled polyelectrolyte films

The loading of methyl orange (MO) in layer-by-layer assembled thin films composed of poly(allylamine hydrochloride) (PAH) and poly(vinyl sulfate) (PVS) or poly(styrenesulfonate) (PSS) and its release from the films were studied. Anionic dye MO can be bound to the PAH-PVS and PAH-PSS films through electrostatic force of attraction. MO fully formed aggregates in the PAH-PVS films, while both monomeric and aggregated forms of MO were found in the PAH-PSS films. The loaded MO can be released from the films into buffer solutions. The release profiles significantly depended on pH and ionic strength of the medium in which MO was released. The release rate was faster in the basic solution than in neutral and acidic media. The release was accelerated in the media with higher ionic strength due to shielding of ionic interactions between MO and positive binding sites in the films.     

Mechanical properties of a laminin–apatite composite layer formed on an ethylene–vinyl alcohol copolymer

A polymeric material with a laminin–apatite composite (L–Ap) layer on its surface would be useful as a material for percutaneous devices with improved cell-adhesion properties and good biocompatibility. Such a laminin–apatite-polymer composite can be prepared using a liquid phase coating process. In this study, the mechanical properties of an L–Ap layer formed on an ethylene–vinyl alcohol copolymer (EVOH) plate were evaluated and compared with those of an apatite (Ap) layer. The laminin immobilized in the L–Ap layer increased the layer's shear strength under wet conditions. However, under dry conditions, there was no advantage of the laminin immobilization on the layer's shear strength and adhesive strength to an EVOH plate. The adhesive strength of the layer to an EVOH plate improved as the thickness of the L–Ap layer decreased from 10 to 3 µm. From these results, it is suggested that a 3 µm thick L–Ap layer is better than a 10 µm thick L–Ap layer on an EVOH surface, and the resulting laminin–apatite–EVOH composite should not be dried when used as a material for percutaneous devices, to avoid any possible adverse effect of drying on the mechanical properties.     

Effects of exogenous mevalonic acid on sterol lipid classes in Larix kaempferi callus

In Japanese larch (Larix kaempferi (Lamb.) Carr.) calli, free sterol (FS), acylsterol (AS) and glycosylsterol, including the acylated type, were found in the proportion of 1.0:0.1:0.8. When the calli were cultured in the presence of 10 mM mevalonic acid (MVA), the content of AS, but not FS and glycosylsterol, was increased remarkably. The major component sterol in each sterol lipid class was usually sitosterol (more than 90%) with campesterol as a minor one. There were no differences on the sterol compositions between the calli cultured with or without MVA. When the calli cultured with 10 mM MVA for 6 weeks were transferred to the control medium without exogenous MVA, AS contents decreased to the level of the control calli. Thus, it was shown that sterol lipids, such as FS and glycosylsterols, with the structural functions was maintained in the constant content and the excess sterol biosynthesized from exogenous MVA was esterified to form AS for storage of sterol components.