Mitsuyasu Kawakami

Modification of gas permeabilities of polymer membranes by plasma coating

Abstract Permeabilities for O2 and N2 were measured of composite films prepared by plasma coating on conventional polymer membranes. Deposition of some nitrogen-containing monomers was found to be effective for the improvement of the permeability ratio for O2/N2 of natural rubber or poly(dimethylsiloxane) used as a substrate. The effects of argon plasma, deposition time, and the kind of substrate on the transport properties of plasma deposits are also discussed.

Selective permeation of ethylene and propylene through rh3+—Polyethylene glycol liquid membranes

Abstract Solubilities and permeabilities of ethylene and propylene were examined for a liquid membrane consisting of polyethylene glycol containing a series of transition metal ions. In the Rh 3+ —added system, olefin uptake by the metal ion occurred reversibly and the permselectivity of olefin gas against N 2 was improved. Addition of KNO 3 to the Rh 3+ —PEG system resulted in further enhancement of the permselectivity. Results of sorption and permeation measurements demonstrated that the olefin transport mediated by Rh 3+ becomes more predominant as a result of the salting-out effect induced by the added salt.

The transport of oxygen facilitated by a CuI–tetraethylenepentamine system

The transport of oxygen is facilitated by a thin liquid layer of the title system which absorbs molecular oxygen reversibly with a stoicheiometry of Cu : O2= 1 : 1 accompanied by a CuI⇌ CuII cycle, causing the flux ratio of oxygen to nitrogen to be as high as 20 : 1

Flow Injection Biosensor System for 2,4-Dichlorophenoxyacetate Based on a Microbial Reactor and Tyrosinase-modified Electrode

Synthetic chlorinated organic compounds have been used extensively as herbicides and pesticides and the contamination of ecosystems with these compounds has stimulated great interest in investigation of these frequently toxic or bioaccumulatable compounds. 2,4-Dichlorophenoxyacetate (2,4-D), one of these compounds, is a synthetic phytohormone that has been widely used as a herbicide for controlling broadleaf weeds, and huge amount of 2,4-D has been released into the environment. 2,4-D is known, on the other hand, to be susceptible to rapid biological degradation in natural environments, and has been used as a model for genetic and biochemical study on the chloroaromatic degradation. A number of its degrading bacteria have been isolated worldwide from a variety of environments and extensively examined on a molecular basis (Amy et al., 1985; Sinton et al., 1986; Perkins et al., 1990; Fulthorpe et al., 1992, 1995; Ka et al., 1994; Tonso et al., 1995; Top et al., 1995; Maltseva et al., 1996; Suwa et al., 1996; Vallaeys et al., 1996; Kamagata et al., 1997; Cavalca et al., 1999; Laemmli et al., 2000; Itoh et al., 2002). One of the most extensively studied strain is Ralstonia eutrophus JMP134, which carries a 2,4-D-degrading gene cluster on the transmissible plasmid pJP4 (Don & Pemberton, 1981; Neilson et al., 1992; Fukumori & Hausinger, 1993a; Laemmli et al., 2000). On the other hand, reliable determination of 2,4-D is indispensable to investigate its biological degradation. A biosensor is a device utilizing a biological sensing element, and a variety of biosensors for 2,4-D detection have been developed (Table 1). Most of sensors reported so far, however, can be classified into either immunoassay or immunoenzymatic assay. They are based on the specific interaction between 2,4-D (antigen) and its antibody. These biosensors have been demonstrated to show very high sensitivities (e.g. the lower detection limit of less than 1 μg/L), while these assays are generally said to be somewhat cumbersome to perform and require considerably expensive reagents. A biosensor based on the inhibition of catalytic activity of enzyme alkaline phosphatase in the presence of 2,4-D has been also proposed and a detection limit of 0.5-6 μg/L has been obtained. The enzyme inhibition effect has been also observed for another pesticide, indicating the analyte selectivity of the sensor to be not expected. On the other hand, very few attempts have been made on the biosensor employing microorganisms as the sensing component.

Immobilization of Two Enzyme System of Glucoamylase and Glucoseoxidase onto Platinum Electrode and its Characteristics as Maltose Sensor.

白金電極をアミノシラン化処理してアミノ基を導入し, このアミノ基を介してグルコアミラーゼ (GA) とグルコースオキシダーゼ (GOD) の2酵素を, 固定化用担体を用いることなく, 同時に白金電極に固定化して2酵素固定化白金電極 (GA-GOD-Pt) を作製した.得られたGA-GOD-Ptと対極としてAg/AgClを組み合わせてマルトースセンサを構成し, その特性を検討した.マルトース濃度検量線はpHが5.5から7.5の範囲においてより高いpHでよりよい直線性を示した.この傾向を理論的考察を援用して説明し, 直線的な検量線を得るためにはGA活性を抑制して使用すべきであることを示した.ステップ応答法による動的特性の測定からGA-GOD-Ptはむだ時間おくれのない一次おくれ系とみなせることを示した.

Analysis of Uric Acid Concentration Using Immobilized Uricase and Catalase Columns Packed with Oxirane Acrylic Particle as Supporting Material.

オキシランアクリル粒子を担体としたウリカーゼおよびカタラーゼ固定化粒子充填カラムを直列に連結した.流量νでpH8.5, 20℃の50mMトリス・ホウ酸緩衝液を連続的に供給し, その中途に濃度C, 容積Gの尿酸溶液を注入した.流出液中の溶存酸素濃度を溶存酸素センサーで測定して, 指示値の時間変化の積分値Sを求めた.得られた結果は以下の通りである.1) ν=7.6～15.3cm3/min, C=0.10～0.50mg/cm3, G=0.05～0.5cm3の範囲について, 化学量論関係から得られるS=151GC/νの関係が成立した.2) 尿酸溶液注入速度がある値以上になるとSの値が所定値よりも小さくなった.3) ウリカーゼカラムの活性は150日間安定であった.4) カタラーゼカラムの使用により, SとGC/νの間に定量的な関係が得られた.カタラーゼカラムを除いた場合にも, 両者の間に比例関係が成立して定量関係に対する修正係数が導入可能であり, 尿酸分析に使用できることがわかった.

Effectiveness factors of fine particle catalysts embedded in silicone rubber.

液相固体触媒反応では通常微粒子触媒が懸濁状態で用いられる.もし触媒をその活性を損なうことなく適当な担体に固定化できれば, 触媒の取り扱いが容易になるなどいろいろな効用が期待できる.本報では, シリコーンゴムに触媒粒子を包埋して固定化する方法の有用性を明らかにするために, Ru-カーボン触媒によるアセトンの水素化をモデル反応として, シリコーンゴム包埋触媒の有効係数を検討した.その結果, Ru-カーボンをシリコーンゴムに包埋することにより触媒活性は約1/20に低下したが, 各反応物のシリコーンゴム中の拡散は十分速く, 包埋触媒の有効係数は本実験範囲内で1に近いことが判った.包埋による触媒活性の低下は, シリコーンゴムが硬化する際に発生するオキシムが触媒毒となる, あるいは Ru一カーボン触媒の細孔内ヘシリコーンゴムが侵入して閉塞するためと考えられる.