Effect of acid–base interaction on the sorption characteristics of liquids in poly(vinylidene fluoride)

The sorption characteristics of various liquids in poly(vinylidene fluoride) (PVDF) were investigated in relation to the Lewis acid–base interaction between the liquids and the polymer. The sorption amount of various liquids and the sorption selectivity of binary mixtures in PVDF were measured and their characteristics were found to be significantly affected by acid–base interaction. The acid–base interaction was evaluated from the Drago constants of PVDF, which were obtained by extending the Fowkes' method observing the shift of stretching frequency of the carbonyl bond of ethylacetate sorbed in PVDF. The partial molar enthalpy change of mixing at infinite dilution was estimated using the Drago constants of PVDF and used as a parameter explaining the sorption characteristics of liquids in PVDF. © 1992 John Wiley & Sons, Inc.     

Battery performance of PMMA-grafted PE separators prepared by pre-irradiation grafting technique

Poly(methyl methacrylate)-grafted polyethylene (PE-g-PMMA) separators were prepared by pre-irradiation grafting technique of methyl methacrylate onto a commercial polyethylene separator. The prepared separators were characterized by using charge/discharge (C/D) cycling test, AC impedance, and thermal stability analyses. Thermal shrinkage (TS) of the PE-g-PMMA separators decreased with an increasing degree of grafting up to 70% above which it was saturated. The PE-g-PMMA separators showed a better oxidation stability on the anode up to 5 V and a better cycle life performance than the original PE separator. These characteristics make the prepared separators suitable for applications in high voltage secondary lithium batteries.     

Synthesis and dispersion of polypyrrole nanoparticles in polyvinylpyrrolidone emulsion

Monodisperse particles of conducting polypyrrole (PPy) were directly synthesized in large quantities by emulsion polymerization with FeCl₃ in organic solvents in the presence of polyvinylpyrrolidone (PVP). The particles were almost spherical form capped with PVP and their sizes ranged from 30 to 60 nm with a narrow size distribution when molecular weight of PVP was 3700k. The particle sizes were decreased with an increase in molecular weight of PVP: as molecular weight is increased from 40k to 3600k, the size is decreased from 90–110 to 60–80 nm, respectively. These PPy particles are easily dispersed in organic solvents such as water, methanol, butanol isopropanol and these solutions can also be blended with organic binder polymers by casting for film formation. The conductivity of pelletized PPy particles was 10–15 S/cm.     

Rate multiplicity due to interactions between adsorbed species

A generalized Langmuir-Hinshelwood mechanism for the reaction A + 1 /2B₂ ⇌ C has been studied. Lateral (nearest neighbor) interactions between the adsorbed species have been considered to analyze the multiple steady-states in the chemical reaction. Forward and reverse reaction rate constants have been evaluated via the lattice-gas model with the absolute rate theory. The simulation by the proposed model can predict multiple steady-states and hysteresis. Experimental correlation was made for the rate multiplicity observed by Sung [3] on CO oxidation reaction.     

Model for attachment of active species onto gelular polymer bead

Equations for the equilibrium between the stresses and the degree of swelling, and also for the mass balance of substrate and functional groups, are proposed in order to analyze the attachment of active species onto gelular polymer bead. The asymptotic expansion technique was used to solve these equations when the relaxation rate of polymer in solvent is higher than the reaction rate and the reaction rate is much faster than the diffusion rate. It was shown that the interaction between solvent and polymer with attachment can be explained from the simulation. The equations proposed can be utilized to better understand the control of active species distributions in the polymer bead. © 1992 John Wiley & Sons, Inc.     

Differential response of glomerular epithelial and mesangial cells after subtotal nephrectomy

Recent studies in both human and experimental chronic renal disease suggest that there is a linkage between glomerular hypertrophy and glomerulosclerosis. To further define these relationships, we studied the changes in glomerular hypertrophy, procollagen alpha 1(IV) mRNA levels and glomerulosclerosis in rats undergoing 1 2/3 nephrectomy (Nx) or sham nephrectomy (SNx). Glomerular hypertrophy, measured biochemically by RNA/DNA and protein/DNA ratios, was significantly increased in Nx compared to SNx two days after subtotal renal ablation (RNA/DNA: Nx = 133 +/- 8%, SNx = 100 +/- 3% of the mean control value, P < 0.01; protein/DNA: Nx = 164 +/- 22%, SNx = 100 +/- 10%, P < 0.05) and remained elevated after 7 and 15 days (RNA/DNA: seven days Nx = 155 +/- 3%, SNx = 100 +/- 13%, P < 0.01; 15 days Nx = 303 +/- 21%, SNx = 100 +/- 24%, P < 0.001; protein/DNA: seven days Nx = 228 +/- 57%, SNx = 100 +/- 18%, P < 0.05; 15 days Nx = 341 +/- 23%, SNx = 100 +/- 18%, P < 0.01). Light microscopic measures of glomerular tuft volume (GTV) were too insensitive to detect glomerular enlargement until 15 days postoperatively, but GTV measured ultrastructurally demonstrated a 20% increment in Nx compared to SNx as early as two days postoperatively (P < 0.01). The latter increment in GTV was due exclusively to glomerular visceral epithelial cell (GVEC) expansion. Glomerular procollagen alpha 1(IV) mRNA levels were significantly elevated only 15 days after nephrectomy (Nx = 265 +/- 58% of the mean control value, SNx = 100 +/- 12%, P < 0.05; corrected for beta-actin mRNA levels). As this time, exuberant mesangial expansion measured ultrastructurally contributed to a 1.6 +/- 0.1-fold increase in GTV (P < 10(-5)), and to a relative decrement in the GVEC contribution to glomerular cells plus matrix (P < 0.01). Segmental sclerosis was observed only 15 days postoperatively in Nx (Nx = 1.3 +/- 0.4% of glomeruli evaluated, SNx = 0.0%, P < 0.05), and there was a strong correlation between the prevalence of segmental sclerosis and the procollagen alpha 1(IV) mRNA levels in Nx at 15 days (r = 0.93, P < 0.01). There was no significant correlation between the RNA/DNA and protein/DNA ratios and procollagen alpha 1(IV) mRNA levels. Thus, glomerular regions responded differentially to subtotal nephrectomy. Early epithelial cell expansion was followed by later mesangial expansion. Glomerular procollagen alpha 1(IV) mRNA levels were elevated only during the second (mesangial) phase of glomerular hypertrophy, when it correlated with glomerulosclerosis, but not during the initial (epithelial) phase, a pattern consistent with a mesangial origin of the procollagen alpha 1(IV) mRNA.     

STATISTICAL THERMODYNAMIC ANALYSIS ON THE SORPTION SELECTIVITY FOR A BINARY LIQUID MIXTURE ON THE SOLID SURFACE

The nonideal concentration dependent sorption selectivity for the liquid-solid interface was analyzed by introducing the admolecular interaction in the statistical thermodynamic approach. The quasi-chemical and Bragg-Williams approximations together with the maximum term condition result in the desired expression for the adsorption isotherm. Experiments were carried out for the adsorption of the binary (xylene/toluene) mixture on the Y-zeolite as a nonideal system. The derived isotherms were correlated with both the ideal system reported by Sircar and Myers and the present nonideal adsorption data.