Synthesis of partially biobased polymer-bearing reactive epoxy groups in the side chains by radical copolymerization of limonene oxide with methyl acrylate

A radical copolymerization behavior of limonene oxide and methylacrylate was investigated, by which a partially biobased polymer-bearing reactive epoxy groups in the side chains was obtained in 43 % yield in the maximum. Degree of LO incorporation into the copolymer was determined to be 34–37 % when 5.0 mol % of 2,2′-azobis(isobutyronitrile) was employed, despite initial feed ratios. Reactivity of the epoxy groups in the side chains was investigated by two different methods. One is ring-opening of the epoxy groups with benzyl thiol, giving the corresponding polymer with β-hydroxyl sulfide moieties in 95 % yield. Another one is hydrolyzation of the epoxy groups in HCl aqueous solution at room temperature, providing a quantitative formation of the dihydroxyl groups in the side chains.     

Performance and durability of nanostructured (La0.85Sr0.15)0.98MnO3/yttria-stabilized zirconia cathodes for intermediate-temperature solid oxide fuel cells

In this communication we report the fabrication of nanostructured (La_0.85Sr_0.15)_0.98MnO₃ (LSM)/yttria-stabilized zirconia (YSZ) composite cathodes consisting of homogeneously distributed and connected LSM and YSZ grains approximately 100 nm large. We also investigate for the first time the role of the cathode nanostructure on the performance and the durability of intermediate-temperature solid oxide fuel cells. The cathodes were fabricated using homogenous LSM/YSZ nanocomposite particles synthesized by co-precipitation, using YSZ nanoparticles of 3 nm as seed crystals. Detailed microstructural characterization by transmission electron microscopy with energy-dispersive X-ray spectroscopy revealed that many of the LSM/YSZ junctions in the cathode faced the homogeneously connected pore channels, indicating the formation of a considerable number of triple phase boundaries. The nanostructure served to reduce cathodic polarization. As a result, these anode-supported solid oxide fuel cells showed high power densities of 0.18, 0.40, 0.70 and 0.86 W cm⁻² at 650, 700, 750 and 800 °C, respectively, under the cell voltage of 0.7 V. Furthermore, no significant performance degradation of the cathode was observed during operation at 700 °C for 1000 h under a constant current density of 0.2 A cm⁻².     

Photo-induced change in wettability and binding ability of azoaromatic polymers

Photochromic polymers containing p-phenylazoacrylanilide were synthesized and the photo-induced hydrophobicity change on the surface of the polymer film was studied by measuring water wettability. The wettability increased with UV irradiation and returned to the original value with visible light irradiation. This photo-induced reversible change in wettability was considered to be caused by the large change of dipole moment across the azo bonds due to the isomerization of azo dye from trans to cis form. Furthermore, the photoresponsive polymeric adsorbent prepared from the azo polymer having adsorption behavior of a low molecular weight compound was studied. The binding ability of this polymeric adsorbent was decreased by UV irradiation. These results were attributed to the decreased hydrophobic interaction between the adsorbent and the adsorbate.     

Surveillance of cadmium level in octopus, squid, clam, short-necked clam and chocolate

In order to investigate cadmium contents in foods sold in Japan, cadmium levels in 40 seafood samples and 30 chocolate samples were measured by means of atomic absorption spectrometry and ICP-OES. We first confirmed the validity of the method according to the guidelines of the Ministry of Health, Labour and Welfare. Among 40 seafood samples investigated, cadmium was detected in 31 samples, in which the concentration exceeded half the LOQ (0.025 mg/kg), and the level was ranged from 0.03 to 0.38 mg/kg. We could not find any sample containing cadmium in excess of 2 mg/kg, which the Codex Alimentarius sets as the maximum standard value. Among 30 chocolate samples, cadmium was detected in 21 samples, and the level ranged from 0.025 to 0.54 mg/kg.     

Inactivation of Shiga toxin-producing Escherichia coli in single-strength lemon and lime juices containing preservatives

The objective of this study was to determine the inactivation of non-O157 Shiga toxin-producing Escherichia coli (STEC) serotypes in comparison with O157 STEC in commercially produced, shelf-stable lemon and lime juices. The present validation tests confirmed that storage of the juices containing preservatives at room temperatures (22°C) for 3 days (72 h) ensures a >6-log reduction of O26, O45, O103, O111, O121, O145, and O157 STEC. These results demonstrate that non-O157 STEC had survival abilities comparable to those of E. coli O157:H7 strains in acidic food products such as lemon and lime juices (pH 2.5 ± 0.1); therefore, the storage conditions deemed to inactivate E. coli O157:H7 similarly inactivate the non-O157 serotypes.     

Formation of protein adducts of 2‐amino‐1‐methyl‐6‐phenylimidazo[4,5‐b]pyridine in cooked foods

Heterocyclic amines (HCAs) are mutagenic and carcinogenic compounds found in cooked meat and fish. Although HCAs are known to form adducts with protein after metabolic activation, adduct formation during cooking has not been elucidated. In this study, we showed that 2‐amino‐1‐methyl‐6‐phenylimidazo[4,5‐b]pyridine (PhIP) is released from high molecular weight compounds by acid or enzymatic hydrolysis of cooked foods. Formation of free and protein adduct forms of PhIP was dependent on cooking temperature and time, and PhIP–protein adducts were estimated to form after formation of free PhIP. We also demonstrated that PhIP–protein adduct is formed by heating of PhIP and albumin as a model protein. A new adduct peak including [M+H]⁺ (m/z=225) of PhIP as a fragment ion was detected in the high molecular weight fraction of heat‐treated protein by LC–MS analysis. From model experiments by heating of PhIP and amino acids, the adduct was estimated to be produced by condensation of the amino group of PhIP and the carboxyl group of protein. PhIP–protein adducts were detected in several cooked meat and fish at ng/g food level as PhIP content. These results suggest that food‐borne protein adducts of HCAs may influence human HCA exposure and carcinogenic risk.     

Purification and characterization of a new aldehyde oxidase from pseudomonas sp. AIU 362

An aldehyde oxidase exhibiting high activity on glyoxal was purified to an electrophoretically homogenous state from Pseudomonas sp. AIU 362, which was isolated from a soil sample using a methoxyethanol medium. The enzyme oxidized not only glyoxal but also short-chain aliphatic aldehydes and aromatic aldehydes. Thus, this enzyme was classified into the aldehyde oxidase (ALOD) group. However, it was composed of four identical subunits with a molecular mass of 27 kDa, whereas other microbial ALODs were composed of three hetero subunits, and ALODs from plant and animals were composed of two identical subunits. The NH(2)-terminal sequence also showed no similarity to that of other ALODs. These results indicate that ALOD from Pseudomonas sp. AIU 362 is a new aldehyde oxidase. This ALOD was induced by 2-methoxyethanol, methanol or isopropanol.