Effect of electro-chemical properties of sodium salts of various anions on their diffusional parameters in symmetrical cellulose acetate membranes

A relation was obtained between electro-chemical properties of sodium salts (NaCl, NaBr, and Na₂SO₄), and the thermodynamic property of permeability in symmetrical cellulose acetate membranes, the distribution coefficient K and the kinetic property, the overall diffusion coefficients D. K and D were obtained by the method we proposed using measured unsteady- and steady-state dialysis data. The K values increase with the increase of water content and are in the range of 10⁻² for sodium halides and 10⁻³ for Na₂SO₄. D is found to increase with the increase of the solute concentration, and the extrapolated values of D to zero concentration D⁽⁰⁾ are obtained as 0.015–0.03 μm²/s and increase with the increase of water content in the membrane. D can be divided into the concentration independent diffusion coefficients in the dense part of the membrane D_d and in the porous D_p, applying a two-part (perfect or dense and imperfect or porous) model of the membrane. Contrary to D_d, D_p increases with the increase of W_w and can be correlated as D_p,c = _d exp (γ × W_w). It is shown that the averaged D_d, _D increases with the increase of the quantity of the ionic mobility u of the solutes at infinite dilution divided by valence, and that the parameter γ increases with the increase of the ionic mobility u. The value of K increases slightly with the increase of water content and decreases with the increase of the Flory—Huggins parameter χ. The Flory—Huggins parameter χ is calculated from the measured values of distribution coefficients and data obtained from the literature. And it was found that the gradient of linear decrease of χ (λ_cation) depends on equivalent ionic conductivity of anion of salt, λ_an.     

Novel vitamin E derivative with 4-substituted resorcinol moiety has both antioxidant and tyrosinase inhibitory properties

A novel vitamin E derivative, (6″-hydroxy-2″,5″,7″,8″-tetramethylchroman-2″-yl) methyl 3-(2′,4′-dihydroxyphenyl)propionate (TM4R), which has a chromanoxyl ring and 4-substituted resorcinol moieties, was synthesized; and its inhibitory effects on tyrosinase, antioxidant ability, and lightening effect of ultraviolet B (UVB)-induced hyperpigmentation were estimated. TM4R showed potent inhibitory activity on tyrosinase, which is the rate-limiting enzyme in melanogenesis. The scavenging activities of TM4R on 1,1-diphenyl-2-picrylhydrazyl and hydroxyl radicals were found to be nearly the same as those of α-tocopherol. Furthermore, an efficient lightening effect was observed following topical application of TM4R to UVB-stimulated hyperpigmented dorsal skin of brownish guinea pigs. These results suggest that TM4R may be a candidate for an efficient whitening agent, possibly by inhibiting tyrosinase activity and biological reactions caused by reactive oxygen species.     

Synthesis of geranyl acetate by lipase entrap-immobilized in cellulose acetate-TiO2 gel fiber

Lipase from Candida antarctica was entrap-immobilized in cellulose acetate-TiO₂ gel fiber (fiber-immobilized lipase) by the sol-gel method. Syntheses of geranyl acetate and citronellyl acetate catalyzed by the fiber-immobilized lipase were studied in heptane solution. Conversions reached 85% for geranyl acetate after 100 h, and 75% for citronellyl acetate after 80 h, and these values were almost identical to those for syntheses catalyzed by nonimmobilized lipase, although the reaction rate was decreased by immobilization. Compared to those of the non-immobilized lipase and commercially available immobilized lipase (Novozyme 435), the activity of the fiber-immobilized lipase was not particularly affected by changes in reaction conditions, such as bulk water content or substrate concentration. The fiber-immobilized lipase retained a high level of activity after six repeated uses, and almost no enzyme leakage from fiber was observed. However, the reactivity of the fiber-immobilized lipase was depressed at higher temperature, presumably due to dehydration by thermal contraction of the gel fiber.     

Mechanism of Particle Separation in Small Hydrocyclone

The mechanism of particle separation in a small hydrocyclone is analyzed in this study. The separation efficiency of particles is affected by two major effects, the centrifugal and underflow effects. The fundamentals of these effects on the selectivity curve are derived from the theories of hydrodynamics. Three JIS particulate samples are separated in a 10-mm hydrocyclone. The proposed mechanism can be demonstrated by the available data. An increase in split ratio leads to an increase in the separation efficiency only for fine particles; consequently, a decrease in the separation sharpness results in a remarkable fishhook phenomenon. When the feed rate is increased by increasing the pressure drop through the hydrocyclone, the entire partial separation efficiency will be improved, but the separation sharpness and fishhook depth have no substantial varieties. The proposed mechanism can be used for explaining these phenomena, for the selection of optimum operating conditions, and for the hydrocyclone design.     

Novel High‐Temperature Antiferroelectric‐Based Dielectric NaNbO3–NaTaO3 Solid Solutions Processed in Low Oxygen Partial Pressures

The (1?x)NaNbO₃–(x)NaTaO₃ solid solution was investigated for x ≤ 0.4 in terms of new high‐temperature and high‐permittivity dielectric system that is suitable for base metal inner electrode capacitor applications. The addition of Ta significantly enhanced the resistivity of the dielectric, resulting in superior resistivity than the dielectrics‐formulated BaTiO₃ systems that dominate the multilayer ceramic capacitor dielectric devices. The voltage dependence of the permittivity was also superior to BaTiO₃‐based materials, providing higher capacitance at higher temperatures. A transmission electron microscopy study illustrated that the grains had so‐called core‐shell structure. According to the electron diffraction analysis, the core region had an inhomogeneous structure between antiferroelectric and ferroelectric phases, and shell region had an incommensurate ferroelectric‐like structure. The core and shell region had Nb‐ and Ta‐rich composition, respectively, and their interface was compositionally sharp, implying that shell region was formed via a liquid phase during the sintering process with an incongruent Ta dissolution reprecipitation. We anticipate that these or similar materials based on the alkali‐niobate perovskites can be further enhanced to provide capacitor solutions from 150°C to 250°C, which is an important range for a number of new AC–DC invertor and engine control units.     

Surface modification of contact lenses using adsorption of ethylene oxide branched copolymers

To examine methods for reducing the amount of adsorbed protein on the surface of contact lenses during use, cationic copolymers containing poly(ethylene oxide) units were synthesized and evaluated as surface modifiers. Poly(ethylene oxide) graft‐branched copolymers of composition 70 mol % dimethylaminoethyl methacrylate (DM) and 30 mol % methoxy polyethylene glycol methacrylate (Mp0G; p = 2, 4, 9; the average number of the ethylene oxide units) were obtained using nonionic monomers containing poly(ethylene oxide) units. The copolymers very efficiently prevented protein adsorption on a contact lens. Contact angle measurements showed that immersion in tear fluid made the lens surface hydrophobic because of adsorption of proteins with hydrophobic residues. The copolymer pretreatment made the lens surface hydrophilic, even after dipping in artificial tear fluid. These results suggest that adsorption of the poly(ethylene oxide) branched copolymer on the contact lens would make the lens surface hydrophilic and prevent protein adsorption. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Enhanced Development of Azoxymethane-Induced Colonic Preneoplastic Lesions in Hypertensive Rats

Metabolic syndrome is associated with an increased risk of colorectal cancer. This study investigated the impact of hypertension, a component of metabolic syndrome, on azoxymethane (AOM)-induced colorectal carcinogenesis using SHRSP/Izm (SHRSP) non-diabetic/hypertensive rats and SHRSP.Z-Lepr^fa/IzmDmcr (SHRSP-ZF) diabetic/hypertensive rats. Male 6-week-old SHRSP, SHRSP-ZF, and control non-diabetic/normotensive Wister Kyoto/Izm (WKY) rats were given 2 weekly intraperitoneal injections of AOM (20 mg/kg body weight). Two weeks after the last injection of AOM, the SHRSP and SHRSP-ZF rats became hypertensive compared to the control WKY rats. Serum levels of angiotensin-II, the active product of the renin-angiotensin system, were elevated in both SHRSP and SHRSP-ZF rats, but only the SHRSP-ZF rats developed insulin resistance, dyslipidemia, and hyperleptinemia and exhibited an increase in adipose tissue. The development of AOM-induced colonic preneoplastic lesions and aberrant crypts foci, was significantly accelerated in both SHRSP and SHRSP-ZF hypertensive rats, compared to WKY normotensive rats. Furthermore, induction of oxidative stress and exacerbation of inflammation were observed in the colonic mucosa and systemically in SHRSP and SHRSP-ZF rats. Our findings suggest that hypertension plays a role in the early stage of colorectal carcinogenesis by inducing oxidative stress and chronic inflammation, which might be associated with activation of the renin-angiotensin system.     

Synthesis of chemically modified chitosans with a higher fatty acid glycidyl and their adsorption abilities for anionic and cationic dyes

Novel chitosan‐based materials with a higher fatty acid glycidyl as the chemically modified agent were synthesized and the adsorption ability of the resulting polymers has been evaluated for typical anionic and cationic dyes. The successful modification was confirmed by the infrared spectroscopic measurements. As the degree of substitution was decreased, the adsorption ability of the chemically modified chitosans for anionic dyes at the higher dye concentration was increased, and the modified chitosans with a lower degree of substitution showed a higher adsorption ability than that of an activated carbon at the higher dye concentration. For cationic dyes, the chemically modified chitosan showed a good adsorption power, especially when the adsorption power was evaluated by the flow methods. The improved adsorption ability of a chemically modified chitosan material was also confirmed by comparing it with that of a crosslinked chitosan material. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2423–2428, 2005