Study of transport of pure and mixed CO2/N2 gases through polymeric membranes

The permeations of pure CO₂ and N₂ gases and a binary gas mixture of CO₂/N₂ (20/80) through poly(dimethylsiloxane) (PDMS) membrane were carried out by the new permeation apparatus. The permeation and separation behaviors were characterized in terms of transport parameters, namely, permeability, diffusion, and solubility coefficients which were precisely determined by the continuous‐flow technique. In the permeation of the pure gases, feed pressure and temperature affected the solubility coefficients of CO₂ and N₂ in opposite ways, respectively; increasing feed pressure positively affects CO₂ solubility coefficient and negatively affects N₂ solubility coefficient, whereas increasing temperature favors only N₂ sorption. In the permeation of the mixed gas, mass transport was observed to be affected mainly by the coupling in sorption, and the coupling was analyzed by a newly defined parameter permeation ratio. The coupling effects have been investigated on the permeation and separation behaviors in the permeation of the mixed gas varying temperature and feed pressure. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 179–189, 2000     

Effects of gamma‐irradiated soybean pod extract on oxidative stress,cancer cell viability,and tyrosinase inhibition

Soybean pods contain abundant dietary fiber and phytochemicals, including phenolic compounds. However, few bioactivity studies have been conducted using soybean pods, while soybean leaves, and seeds have been well characterized. In this study, the effect of gamma irradiation on the physiological properties of soybean pod extract (SPE) was investigated. SPE was irradiated at 0, 5, 10, and 20 kGy, and the phenolic compound concentration and antioxidant activity were investigated. The total phenolic compounds were increased and total flavonoids were decreased as the irradiation dose increased. Antioxidant activity, which was measured using the 2,2‐diphenyl‐1‐picrylhydrazyl, 2,2′‐azino‐bis‐3‐ethylbenzothiazoline‐6‐sulphonic acid, and 2‐thiobarbituric acid reactive substances assays, improved as the irradiation dose increased. In addition, cancer cell viability, and tyrosinase activity were reduced by gamma irradiation. These results show that soybean pods can be utilized as functional food materials after gamma irradiation.

Practical applications

Gamma irradiation modified the chemical composition of soybean pod extract (SPE). Such irradiation improved the antioxidant, anti‐pigmentation, and anti‐carcinogenesis effects compared to those of control SPE. Therefore, this material, previously considered a byproduct of soybean processing, can be used as a functional food to prevent such disorders as oxidative damage, cancer, and hyperpigmentation.     

In Vitro One-Pot 3-Hydroxypropanal Production from Cheap C1 and C2 Compounds

One- or two-carbon (C1 or C2) compounds have been considered attractive substrates because they are inexpensive and abundant. Methanol and ethanol are representative C1 and C2 compounds, which can be used as bio-renewable platform feedstocks for the biotechnological production of value-added natural chemicals. Methanol-derived formaldehyde and ethanol-derived acetaldehyde can be converted to 3-hydroxypropanal (3-HPA) via aldol condensation. 3-HPA is used in food preservation and as a precursor for 3-hydroxypropionic acid and 1,3-propanediol that are starting materials for manufacturing biocompatible plastic and polytrimethylene terephthalate. In this study, 3-HPA was biosynthesized from formaldehyde and acetaldehyde using deoxyribose-5-phosphate aldolase from Thermotoga maritima (DERA_Tma) and cloned and expressed in Escherichia coli for 3-HPA production. Under optimum conditions, DERA_Tma produced 7 mM 3-HPA from 25 mM substrate (formaldehyde and acetaldehyde) for 60 min with 520 mg/L/h productivity. To demonstrate the one-pot 3-HPA production from methanol and ethanol, we used methanol dehydrogenase from Lysinibacillus xylanilyticus (MDH_Lx) and DERA_Tma. One-pot 3-HPA production via aldol condensation of formaldehyde and acetaldehyde from methanol and ethanol, respectively, was investigated under optimized reaction conditions. This is the first report on 3-HPA production from inexpensive alcohol substrates (methanol and ethanol) by cascade reaction using DERA_Tma and MDH_Lx.     

Effects of nitrogen sources on toluene degradation by Pseudomonas putida BZ918

For effective toluene degradation, the effects of a nitrogen source were studied with Pseudomonas putida BZ912, which was isolated from crude oil contaminated soil and is capable of degrading VOC. Two nitrogen sources, ammonia and nitrate, showed different effects on specific growth rates (0.25 hr⁻¹ and 0.12 hr⁻¹, respectively), biomass yields (0.56 vs. 0.39) and specific toluene degradation rates (0.51 hr⁻¹ vs. 0.26 hr⁻¹). Under the resting cell conditions, the cells pre-cultured in the ammonia-containing medium showed higher specific toluene degradation rate than that in nitrate-containing medium (0.045 hr⁻¹ vs. 0.038 hr⁻¹). Ammonia as a nitrogen source was effective for degradation in high toluene concentration because high cellular biomass was accomplished. Nitrate showed slow growth rate compared to ammonia. The resting cell conditions demonstrated that it was able to degrade toluene efficiently without increasing biomass. These conditions could be a solution for degrading VOC after high cellular biomass was obtained in a biofilter. By changing the nitrogen source and the growth conditions according to the toluene concentration, the control of cell biomass and the desired removal capacity were accomplished.     

Conformal electroless deposition of Cu seed layer on a 60-nm trench pattern modified with a self-assembled monolayer

We have developed a novel activation technique for the conformal electroless deposition (ELD) of Cu on a SiO₂ substrate modified with an organic self-assembled monolayer. The SiO₂ substrate was modified with amine groups using 3-aminopropyltriethoxysilane and Au nanoparticles (AuNPs) to form a uniform, continuous catalyst for ELD. The Au catalytic layer formed on the amine-SiO₂ substrate was stabilized by electrostatic interactions between the positively charged protonated-amine self-assembled monolayer (SAM) and negatively charged AuNPs. Cu films were then electrolessly deposited on Au-catalyzed SiO₂ substrates. The Cu seed layer formed by this method showed a highly conformal and continuous structure. Cu electrodeposition on the 60-nm trench was demonstrated using an acid cupric sulfate electrolyte containing chloride, polyethylene glycol 4000 and bis(3-sulfopropyl)disulfide. The resulting electroplated Cu showed excellent filling capability and no voids or other defects were observed in a 60-nm trench pattern.     

Preparation of a reticulated polyurethane foam grafted with poly(acrylic acid) through atmospheric pressure plasma treatment and its lysozyme immobilization

We successfully introduced peroxide groups onto the surface of PU(Polyurethane) foam(10 PPI) through one atmospheric pressure plasma treatment and sequentially grafted PAAc(poly(acrylic acid)) on the surface of PU through radical copolymerization. The plasma treatment can generate large amount of peroxides on the surface of PU foam and the peroxide groups act as initiators for further grafting of PAAc in the monomer solution. To introduce large amount of peroxides on the surface of PU foam, we studied the effect of plasma rf-power and treatment time on the maximum grafting of PAAc. Through this study, we found that the optimum plasma treatment condition was the rf-power of 100 W and the treatment time of 100 s. On the other hand, we also studied the effect of graft reaction conditions such as temperature, monomer concentration and reaction time on the change of grafting degree (GD). The GD increased with increasing temperature and increased with reaction time before it leveled off at 3 h after reaction started. At low concentration of AAc, the GD was very low but it showed a maximum at the monomer concentration between 60 and 70%. The surface of the modified PU foam was qualitatively and quantitatively analyzed through the use of FT-IR and weight measurement, respectively. We also observed the surface change before and after plasma induced graft co-polymerization through photo and SEM analysis. Finally, we confirmed that the PU foams grafted with PAAc successfully immobilized lysozyme and other proteins from hen egg white.     

Treatment of dairy wastewater using anaerobic and solar photocatalytic methods

The present study was aimed to treat the dairy wastewater by using anaerobic and solar photocatalytic oxidation methods. The anaerobic treatment was carried out in a laboratory scale hybrid upflow anaerobic sludge blanket reactor (HUASB) with a working volume of 5.9 L. It was operated at organic loading rate (OLR) varying from 8 to 20 kg COD/m³ day for a period of 110 days. The maximum loading rate of the anaerobic reactor was found to be 19.2 kg COD/m³ day and the corresponding chemical oxygen demand (COD) removal at this OLR was 84%. The anaerobically treated wastewater at an OLR of 19.2 kg COD/m³ day was subjected to secondary solar photocatalytic oxidation treatment. The optimum pH and catalyst loading for the solar photochemical oxidation was found to be 5 and 300 mg/L, respectively. The secondary solar photocatalytic oxidation using TiO₂ removed 62% of the COD from primary anaerobic treatment. Integration of anaerobic and solar photocatalytic treatment resulted in 95% removal of COD from the dairy wastewater. The findings suggest that anaerobic treatment followed by solar photo catalytic oxidation would be a promising alternative for the treatment of dairy wastewater.     

Internal Alkene Hydroaminations Catalyzed by Zirconium(IV) Complexes and Asymmetric Alkene Hydroaminations Catalyzed by Yttrium(III) Complexes

The thiophosphinic amide 2 was prepared in 68 % yield by the reaction of 2,2‐dimethyl‐1,3‐propanediamine with diisopropylchlorophosphine followed by the addition of sulfur. Attachment of the proligand 2 to zirconium was achieved by direct metalation with Zr(NMe₂)₄ in benzene‐d₆ or toluene‐d₈ to afford complex 3 via elimination of dimethylamine. The neutral Zr(IV) complex 3 has been shown to be an effective precatalyst for intramolecular alkene hydroaminations that provide cyclic amines in good to excellent yields. A variety of chiral ligands ( 20 , 22 , 24 , and 25 – 30 ) were prepared for asymmetric internal alkene hydroaminations. Metalation of chiral ligands to yttrium was accomplished with Y[N(TMS)₂]₃ in benzene‐d₆ or toluene‐d₈ to give complexes. Treatment of 7 with 5 mol % of 33 in benzene‐d₆ (25 °C, 18 h) or toluene‐d₈ (25 °C, 15 h) afforded 2,4,4‐trimethylpyrrolidine 14 in 95 % yield (61 % ee).