Surface area/volume ratio

Direct bonding. In many high-volume production applications (i.e., the automotive and appliance industries), elaborate surface preparation of steel ad-herends is undesirable or impossible. Thus, there has been widespread interest in bonding directly to steel coil surfaces that contain various protective oils [55,56,113-116], Debski et al. proposed that epoxy adhesives, particularly those curing at high temperatures, could form suitable bonds to oily steel surfaces by two mechanisms (1) thermodynamic displacement of the oil from the steel surface, and (2) absorption of the oil into the bulk adhesives [55,56]. The relative importance of these two mechanisms depends on the polarity of the oil and the surface area/volume ratio of the adhesive (which can be affected by adherend surface roughness). 

In vivo biocompatibility was assessed through subcutaneous implantation in Sprague-Dawley rats. PLGA was used as a control polymer. PGS and PLGA implants with the same surface area/volume ratio were implanted in dorsal subcutaneous pockets. A fibrous capsule around PGS (45 pm thick after 35 days implantation) appeared later than that around PLGA (140 pm thick after 14 days implantation). After 60 days of implantation, the implant was completely absorbed with no signs of granulation or scar formation. ... 

There are surprisingly few studies of the retention mechanism for open tubular columns but the theory presented for packed columns should be equally applicable. For normal film thicknesses open tubular columns have a large surface area/volume ratio and the contribution of interfacial adsorption to retention should be significant for those solutes that exhibit adsorption tendencies. Interfacial adsorption has been shown to affect the reproducibility of retention for columns prepared with nonpolar phases of different film thicknesses [322-324]. The poor reproducibility of retention index values for columns prepared from polar phases was demonstrated to be c(ue to interfacial... 

The pore size of the membrane could also be controlled independently of the porosity by altering the size of the salt particles (Fig. 5a). Membranes with high surface area/volume ratios were produced and the ratio was dependent on both salt weight fraction and particle size (Fig. 5b). In addition, the crystallinity of PLLA membranes can be tailored to that desired for each application. These characteristics are all desirable properties of a scaffold for organ regeneration. The major disadvantage of this technique is that it can only be used to produce thin wafers or membranes (up to 2 mm in thickness). A three-dimensional scaffold cannot be directly constructed. This problem may be circumvented however, by membrane lamination. 

Conditions. Table II provides temperature, pressure, and other conditions for the experiments. The surface area/volume ratio for all experiments was 2.7 x 103 cm 1. The hydrothermal apparatus was a Dickson-type sampling autoclave with a gold-titanium reaction cell, a gold-lined sampling tube, and a titanium sampling valve block (11). Samples of the reacting fluid could be taken over time without disturbing the pressure-temperature conditions of a run. The autoclaves were rocked 180 at about 4 cycles/min. 

The experimental results of this study may also be applicable to processes occurring in the disturbed rock zones around a waste package. The surface area/volume ratio for these experiments is approximately equivalent to the solution in a 10-pm-wide planar fracture (33). With a fracture abundance of... 

Rosenberg, G., and Ramus, J. (1984) Uptake and inorganic nitrogen seaweed surface area volume ratios. Aquat. Bot. 19, 65-72. 

Nanomaterials can be in the form of fibers (one-dimensional), thin films (two-dimensional), or particles (three-dimensional). A nanomaterial is any material that has at least one of its dimensions in the size range 1 to 100 nm (Figure 6.1). Many physical and chemical properties are determined by the very large surface area/volume ratio associated with such ultrasmall particles. There are two major categories into which all nanomaterial preparative techniques can be grouped the physical, or top-down, approach and the chemical, or bottom-up, approach. In this chapter, our primary focus is on chemical synthesis. Nevertheless, we discuss the physical methods briefly, as they have received a great deal more interest in the industrial sector because of their promise to produce large volumes of nanostructured solids. 

The large surface area/volume ratio of nanoparticles means that most of their atoms are on the surface, which allows nanoparticles to react as nearly stoichiometric reagents in chemical reactions, unlike bulk solids. For example, a six-atom cluster in the shape of an octahedron contains 100 percent of its atoms on the surface. If either the CCF or HCF theme is followed, the next smallest close-packed collection of atoms that can be built has a central atom coordinated to six others in one layer, three others in a layer above, and three in a layer beneath. Hence, 12/13 = 92 percent of the atoms in this cluster... 

Figure 6.4. Comparison of the surface area/volume ratio of macroscopic particles (marbles) and nanoscopic aluminum oxide particles. Since nanoparticules contain a proportionately large number of surface atoms, there are a significantly greater number of adsorption/reaction sites that are available to interact with the surrounding environment. Further, whereas bending of a bulk metal occurs via movement of grains in the >100nm size regime, metallic nanostructures will have extreme hardness, with significantly different malleability/ductility relative to the bulk material.

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