Micrograph particles

From the TEM micrographs, particle sizes and the number of particles per unit area could be estimated. Figure 16.6 provides a quantitative analysis of the particle sizes as a function of deposition time. It is evident from the particle size distributions that at low nominal Au thickness (0.13 nm), mean particle diameters are about 1.4 nm and fall in a narrow range of sizes. As the nominal thickness becomes higher, the particle... 

Figure 4. TEM micrograph particle size distribution of Pt-Pd (1 1) 20 wt%. Reprinted from C. Coutanceau, L. Demarconnay, C. Lamy and J.-M. Leger, Development of eleotrocatalysts for solid alkaline fuel cell (SAFC), Journal of Power Sources, 156 (2006) 14-19, Copyright (2006), with permission from Elsevier.

Figure Bl.17.8. Iron oxide particles coated with 4 nm of Pt in an m-planar magnetron sputter coater (Hennann and Mtiller 1991). Micrographs were taken in a Hitachi S-900 in-lens field emission SEM at 30,000 primary magnification and an acceleration voltage of 30 kV. Image width is 2163 nm.

Figure C2.11.2. A scanning electron micrograph showing individual particles in a poly crystalline alumina powder.

Figure C2.11.3. A scanning electron micrograph of tire spherical alumina granules produced by spray drying a ceramic slurry. The granules are comprised of individual alumina particles, sintering additives, and an organic binder.

Figure C2.17.2. Transmission electron micrograph of a gold nanoneedle. Inverse micelle environments allow for a great deal of control not only over particle size, but also particle shape. In this example, gold nanocrystals were prepared using a photolytic method in surfactant-rich solutions the surfactant interacts strongly with areas of low curvature, thus continued growth can occur only at the sharjD tips of nanocrystals, leading to the fonnation of high-aspect-ratio nanostmctures [52].

Figure C2.17.4. Transmission electron micrograph of a field of Zr02 (tetragonal) nanocrystals. Lower-resolution electron microscopy is useful for characterizing tire size distribution of a collection of nanocrystals. This image is an example of a typical particle field used for sizing puriDoses. Here, tire nanocrystalline zirconia has an average diameter of 3.6 nm witli a polydispersity of only 5% 1801.

Fig. 13. Transmission electron micrograph (tern) showing dislocations in aluminum in the region near a siUcon carbide particle, SiC. ...

An alternative mechanism involves a physical reorientation of particles at constant total volume to form clumps that have much larger pores (74). Electron micrographs of successive changes in morphology as a function of steeping time in hot water are offered in support of this interpretation. 

Fig. 5. Micrographs of the microstructure of fully hardened and tempered tool steels produced by the powder metallurgy technique, showing uniform distribution and fine carbide particles in the matrix, (a) M-42 (see Table 6) and (b) cobalt-free AlSl T-15 having a higher concentration of fine carbide...

Slides Split-shell bearings hard particles embedded in soft bearing alloys micrograph of section through layered bearing shell skiers automobile tyres. 

Rossmann suggested that the canyons form the binding site for the rhi-novirus receptor on the surface of the host cells. The receptor for the major group of rhinoviruses is an adhesion protein known as lCAM-1. Cryoelectron microscopic studies have since shown that ICAM-1 indeed binds at the canyon site. Such electron micrographs of single virus particles have a low resolution and details are not visible. However, it is possible to model components, whose structure is known to high resolution, into the electron microscope pictures and in this way obtain rather detailed information, an approach pioneered in studies of muscle proteins as described in Chapter 14. 

However, if one attempted to determine iua from the DMT theory, one would get an unrealistically large value. In the same paper, the authors also presented micrographs of particles in contact with the substrate under a negative applied load that was not quite sufficient to effect detachment. It was reported that the observed contact radius under those circumstances was approximately 70% of the expected contact in the absence of the applied load. This observation is in apparent agreement with the JKR prediction that detachment occurs under negative loads that reduce the contact to about 63% of the equilibrium contact radius. 

Fig. I. High-resolution electron micrographs of graphitic particles (a) as obtained from the electric arc-deposit, they display a well-defined faceted structure and a large inner hollow space, (b) the same particles after being subjected to intense electron irradiation (note the remarkable spherical shape and the disappearance of the central empty space) dark lines represent graphitic layers.

The advantages of monosized chromatographic supports are as follows a uniform column packing, uniform flow velocity profile, low back pressure, high resolution, and high-speed separation compared with the materials of broad size distribution. Optical micrographs of 20-p,m monosized macroporous particles and a commercial chromatography resin of size 12-28 p,m are shown in Fig. 1.4. There is a clear difference in the size distribution between the monodispersed particles and the traditional column material (87). 

FIGURE 1.4 Optical micrograph of macroporous chromatographic column materials, (a) Monosized particles of 20 tm. (b) Commercial column filling of 12-28 tm. [Reprinted from T. Ellingsen et al. (1990). Monosized stationary phases for chromatography.7. Chromawgr. 535,147-161 with kind permission from Elsevier Science-NL, Amsterdam, The Netherlands.]... 

Figure 1.5 shows the cumulative pore volume curve for 5-/rm monosized porous PS-DVB particles with 50, 60, and 70% porosity. The curves were drawn by overlapping the measurements from nitrogen adsorption-desorption and mercury intrusion. A scanning electron micrograph of 5-/rm monosized particles with 50% porosity is shown in Fig. 1.6 (87). 

FIGURE 21.23 Electron micrograph of sub-mitochondrial particles showing the 8.5-nm projections or particles on the inner membrane, eventnally shown to be Fj-ATP synthase. (Parsons, D. E, 1963. Science 140 985)... 

The mitochondrial complex that carries out ATP synthesis is called ATP synthase or sometimes FjFo-ATPase (for the reverse reaction it catalyzes). ATP synthase was observed in early electron micrographs of submitochondrial particles (prepared by sonication of inner membrane preparations) as round, 8.5-nm-diameter projections or particles on the inner membrane (Figure 21.23). In micrographs of native mitochondria, the projections appear on the matrixfacing surface of the inner membrane. Mild agitation removes the particles from isolated membrane preparations, and the isolated spherical particles catalyze ATP hydrolysis, the reverse reaction of the ATP synthase. Stripped of these particles, the membranes can still carry out electron transfer but cannot synthesize ATP. In one of the first reconstitution experiments with membrane proteins, Efraim Racker showed that adding the particles back to stripped membranes restored electron transfer-dependent ATP synthesis. 

As shown in Fig. 2a, the size of PVAc particles was found to have a range of approximately 0.1-1.0 /u,m from electron micrograph of the crack surface of the latex... 

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