Test Method for Evaluating the Effective Surface Area of Zinc Oxide in Rubber

It is often said that the sensitivity of a gas sensor made of an oxide semiconductor film is enhanced by making the film porous. However, the porosity of sensor films has not been sufficiently examined. In this study, SnO2 films were deposited using DC magnetron sputtering under various substrate temperatures and discharge gas pressures. In addition to the structural analysis by means of X-ray diffraction and scanning electron microscopy, the density and the BET surface area were measured to clarify the film porosity. The sensitivity to H2 gas of undoped and Pd-doped SnO2 films upon exposure to 1000 ppm H2 was measured at 300 . SnO2 films generally showed a columnar structure. The film deposited at a low temperature and a high pressure showed a low density and a large effective surface area. The H2 sensitivity increased as the density decreased, that is, as the effective surface area increased.

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Day-To-Day Variability of Protein Transport Used as a Method for Analyzing Peritoneal Permeability in CAPD

Peritoneal Dialysis International ◽

10.1177/089686089101100306 ◽

1991 ◽

Vol 11 (3) ◽

pp. 217-223 ◽

Cited By ~ 45

Author(s):

Désirée Zemel ◽

Raymond T. Krediet ◽

Gerardus C.M. Koomen ◽

Dirk G. Struijk ◽

Lambertus Arisz

Keyword(s):

Surface Area ◽

Structural Changes ◽

Protein Transport ◽

Intrinsic Permeability ◽

Effective Surface Area ◽

Intraindividual Variation ◽

Effective Surface ◽

Peritoneal Surface ◽

Beta 2 ◽

Beta 2 Microglobulin

The transperitoneal transport of macromolecules is dependent on both effective peritoneal surface area and intrinsic permeability of the peritoneum. For passage of small solutes, the effective surface area is the main determinant. We hypothesized that day-to-day variations in peritoneal clearances are caused by changes in the effective surface area and not in the intrinsic permeability. Four CAPD {continuous ambulatory peritoneal dialysis) patients without peritonitis were investigated on 28 consecutive days. Concentrations of beta-2-microglobulin, albumin, IgG, and alpha-2-macroglobulin were determined daily in dialysate {night bags) and weekly in serum. Clearances and their coefficients of variation were calculated. Mean coefficients of the intraindividual variation of protein clearances increased, the higher the molecular weight: they ranged from 12% for beta-2microglobulin clearance to 22% for alpha-2-macroglobulin clearance. Correlations were present between the clearances of albumin, IgG, and alpha-2-macroglobulin, but not between any of these and beta-2-microglobulin clearance. In all patients, protein clearance {C) was a power function of the free diffusion coefficient in water {D) according to the equation: C=a. Db in which b represents the restriction coefficient of the peritoneum, and thus intrinsic permeability. The coefficient of variation of the restriction coefficient was low (range 4–6%). This supports our assumption that the intrinsic permeability is fairly constant on the short term. Day-to-day variations in protein clearances are thus mainly caused by alterations in the effective peritoneal surface area. Longterm follow-up of the restriction coefficient in individual patients might identify those at risk for the development of structural changes in the peritoneal membrane.

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