Use of chitosan for removal of bisphenol a from aqueous solutions through quinone oxidation by polyphenol oxidase

In this study, a combined use of biopolymer chitosan and oxidoreductase polyphenol oxidase (PPO) was applied to the removal of bisphenol A (BPA) as an endocrine disrupting chemical from aqueous solutions. The optimum conditions for the enzymatic quinone oxidation of BPA were determined to be pH 7.0 and 40°C. Quinone derivatives generated were chemisorbed on chitosan beads, and BPA was completely removed at 4–7 h. The removal time was shortened with an increase in the amount of dispersed chitosan beads or the PPO concentration. In addition, the initial velocity of quinone oxidation increased with an increase in the amount of chitosan beads. The use of chitosan in the form of porous beads was more effective than the use of chitosan in the form of solutions or powder. It was found that an important factor for this procedure was a high‐specific surface area of chitosan beads and heterogeneous reaction of quinone derivatives enzymatically generated with chitosan. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Tumor angiogenesis of non-small cell lung cancer

Lung cancer is one of the commonest causes of cancer death in developed countries. Recent evidence suggests that angoigenesis is related to poor prognosis in many solid tumors including non-small cell lung cancer (NSCLC). Angiogenesis is regulated by a complex interaction among growth factors and cytokines and influenced by proteolytic enzymes such as plasminogen activators and matrix metalloproteases, expression of adhesion molecules, and distribution of extracellular matrices. Fibroblasts, macrophages, mast cells, and endothelial cells themselves also affect angiogenesis. This review concentrates on angiogenic growth factors including vascular endothelial growth factor, angiopoietins, platelet derived endothelial growth factor, and basic fibroblast growth factor, proteases, adhesion molecules including vascular endothelial cadherin and integrins, osteopontin, and mast cell products in tumor angiogenesis of NSCLC.     

γ-ray irradiation durability of erbium-doped fibres

The long-term behaviour of erbium-doped fibres under γ-ray irradiation at a low dose rate of 0.5R/year was predicted for the purpose of applying the fibres to transoceanic transmission systems, based on the experimental result that permanent defects in fibres were dominantly generated at low dose rates. The estimated degradation of transmission loss and amplification gain after 25 years in undersea were 0.04 dB/km and 0.3 dB, respectively     

Silica-based functional fibers with enhanced nonlinearity and theirapplications

Silica-based optical fibers are now being used in various applications which utilize nonlinear effects in fiber. In addition to enhancing nonlinearity of optical fibers, tailoring chromatic dispersion is one of the important design issues in such applications. Highly nonlinear dispersion-shifted fibers have been developed, and a very compact wavelength converter module has been demonstrated by using the fiber. Dispersion-flattened and dispersion-decreasing fibers have also been proved to be highly effective for supercontinuum generation     

Removal of alkylphenols by the combined use of tyrosinase immobilized on ion‐exchange resins and chitosan beads

Mushroom tyrosinase was covalently immobilized on a poly(acrylic acid)‐type, weakly acidic cation‐exchange resin (Daiaion WK10, Mitsubishi Chemical Corp., Tokyo, Japan) with 1‐ethyl‐3‐(3‐dimethylaminopropyl)carbodiimide hydrochloride salt as a water‐soluble carbodiimide. Ion‐exchange resins immobilized with tyrosinase were packed in one column, and crosslinked chitosan beads prepared with epichlorohydrin were packed in another column. The enzymatic activity was modified by covalent immobilization, and the immobilized tyrosinase had a high activity in the temperature range of 30–45°C and in the pH range of 7–10. When solutions of various alkylphenols were circulated through the two columns packed with tyrosinase‐immobilized ion‐exchange resins and crosslinked chitosan beads at 45°C and pH 7 (the optimum conditions determined for p‐cresol), alkylphenols were effectively removed through quinone oxidation with immobilized tyrosinase and subsequent quinone adsorption on chitosan beads. The use of chemically crosslinked chitosan beads in place of commercially available chitosan beads was effective in removing alkylphenols from aqueous solutions in shorter treatment times. The removal efficiency increased with an increase in the amount of crosslinked chitosan beads packed in the column because the rate of quinone adsorption became higher than the rate of enzymatic quinone generation. The activity of tyrosinase was iteratively used by covalent immobilization on ion‐exchange resins. One of the most important findings obtained in this study is the fact that linear and branched alkylphenols suspected of weak endocrine‐disrupting effects were effectively removed from aqueous solutions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Novel cytotoxic diterpenes from the stem of Dysoxylum kuskusense

Three novel diterpenes, dysokusones A (1), B (2), and C (3), were isolated from the stem of Dysoxylum kuskusense as cytotoxic substances. The structures were established by spectroscopic examinations. Compounds 1, 2, and 3 were cytotoxic toward HL-60(TB) cells with EC50 values of 2.25, 6.35, and 2.37 microM, respectively. Compound 1 also displayed cytotoxicity against K-562 and NCI-H522 cells with EC50 values of 5.04 and 4.80 microM, respectively.     

In situ ellipsometry of porous low-dielectric constant films in supercritical carbon dioxide

This paper reports the results of in situ ellipsometric measurements on porous low-dielectric constant thin films being placed in a mixture of supercritical CO₂ and an organic solvent, intending the detection of the pores. Different low-k films having a dielectric constant of 2.2-3.1 were examined at pressures of 10-14 MPa and temperatures of 40-100 °C. Large changes in ellipsometric parameters were observed upon the addition of the solvent, in any condition studied, when spin-on-dielectric films that have micropores were used. Measurement conditions for films with a smaller pore size were explored and the detection of supermicropores in plasma-enhanced chemical-vapor-deposited SiOCH was succeeded.