Surface pores, scanning electron

Filtering the tube suspension through a 0.2 xm pore ceramic paper leaves a uniform black deposit on the paper and can produce aligned CNT films [30]. The deposited material was transferred on a thin Teflon sheet by pressing the tube-coated side of the filter on the plastic and then the filter was lifted off to expose the surface. Scanning electron microscopic study reveals that the tubes are highly aligned perpendicular to the Teflon surface [30]. 

For efficient separation, porous inorganic membranes need to be crack-free and uniform in pore size. An important reason for the increasing acceptance of ceramic membranes introduced in recent years is the consistent quality as exemplified in a scanning electron micrograph of the surface of a 0.2 micron pore diameter alumina membrane (Figure 3.3). 

Various noncellulosic thln-film-composlte membranes were examined by scanning electron microscopy (SEM). Figure 3 illustrates the type of surface structure and cross-sections that exist in these membranes. Figure 3a shows the surface microporosity of polysulfone support films. Micropores in the film were measured by both SEM and TEM typically pore radii averaged 330 A. Figure 3b is a photomicrograph of a cross-section of a NS-lOO membrane. 

Pore dimensions may have a more subtle effect on decay rate depending on component dimensions and production method of the manufactured material. Products made from pasted starch, LDPE, and EAA (2) typically appeared as laminates of starch and plastic when examined by scanning electron microscopy (Figure 1). The dimensions of inter-laminate channels (i.e., pores) were not uniform and ranged from about 50 to 325 m in cross-section (22). Since flux is dependent on diffusional path area, the smaller pores can be an impediment to movement of solutes from the interior to the surface of the films. Figure 5 illustrates two films in which the laminate units are the same thickness, but differ in length. When the starch is removed... 

Fig. 7a, b. Scanning electron photomicrographs of PLLA foams of pore size 250-500 pm a cross-section at low magnification after 30 days of chondrocyte culture b and on the surface at high magnification after 28 days of chondrocyte culture (Reproduced with permission from [39])... 

Scanning electron microscopic examination before and after dissolution and in vivo implantation show no significant changes in surface topography for the implants prepared as they are clinically used, that is, without additives. However, distinct changes in surface characteristics and the appearance of pores are evident with the inclusion of water-soluble additives such as polyethylene glycol 400. 

Figure 25-5 Scanning electron micrographs of silica chromatography particles, (a) Aggregate of spherical particles with 50% porosity and a surface area of 150 m2/g. (b) Spongelike structure with 70% porosity and a surface area of 300 m2/g. Pores are the entryways into the interior of the particles. In both cases, the nominal pore size is 10 nm, but the distribution of pore sizes is greater in the spongelike structure. The spongelike structure also dissolves more readily in base. [From Hewlett-Packard Co. and R. Majors, LCGC May 1997, p. S8.J...

The new composite (SC-155) and some of its precursors and derivatives were characterized by LOI (loss on ignition), XRD ( X ray diffraction), 1R (infrared spectra), BET specific surface area, nitrogen adsorption desorption isotherms, pore size distribution (mercury porosimetry), dynamic methylene blue adsorption and SEM (Scanning Electron... 

Figure 7.3 Surface scanning electron micrograph and schematic comparison of nominal 0.45-p.m screen and depth filters. The screen filter pores are uniform and small and capture the retained particles on the membrane surface. The depth filter pores are almost 5-10 times larger than the screen filter equivalent. A few large particles are captured on the surface of the membrane, but most are captured by adsorption in the membrane interior...

Fig. 2a. Scanning electron micrograph of bare surface of GORE-TEX with 0.02 pm effective pore size. Magnification 20,000 x. Bar represents 500 nm.

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