Crystal drawing

FIGURE 20.7 (a) Example of conventional orientation of crystallographic axes, (b) 1, 

Octahedron with front faces indexed 2, cube with front faces indexed. 

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RNase Ti solution—We use product R-1003 from Sigma, which is supplied as a crystalline suspension in 3.2 M ammonium sulfate (300,000-600,000 units/mg of protein). Transfer a volume equivalent to 1 mg of protein (consult the specification sheet) to a microcentrifuge tube and centrifuge for 5 min to collect the crystals. Draw off the supernatant and resuspend the solid crystals in 2 ml of distilled water. 

Crystal drawing can be carried out by using the following diagram (Figure 20.7a). Examples of the conventional orientation of crystallographic axes are illustrated with an octahedron and a cube (Figure 20.7b). 

Calculate the surface energy at 0 K of (100) planes of radon, given that its energy of vaporization is 35 x 10 erg/atom and that the crystal radius of the radon atom is 2.5 A. The crystal structure may be taken to be the same as for other rare gases. You may draw on the results of calculations for other rare gases. 

Institute of Technology (MIT) [193]. Molecules were represented as line drawings on a homemade display (an oscilloscope (Figure 2-122). In addition, the system had diverse peripherals with many switches and buttons which allowed the modification of the scene. The heart of the. system was the. so-called Crystal Ball" which could rotate the molecule about all three orthogonal axes. This prototype cost approximately two million US dollars. 

If it is desired to observe the crystalline form of the osazone, draw up in a glass tube a few drops of the cold filtrate containing the fine crystals, and transfer to a microscope slide. Cover the drops with a slip and examine under the microscope unless the filtrate has been cooled very slowly and thus given moderately-sized crystals, the high power of the microscope will probably be required. Note the fine yellow needles aggregated in the form of sheaves. Compare with Fig. 63(A). 

The resin has the ability to be oriented by a drawing process and crystallized to yield a high-strength product. 

When we speak of the solidification of the extruded polymer, we use the term in the broadest sense It includes crystallization, vitrification, or both. The extent of the drawing of the fibers and the rate and temperature of the drawing affect the mechanical properties of the fiber produced. This conclusion should be evident from a variety of ideas presented in the last three chapters ... 

At HOY speeds, the rate of increase in orientation levels off but the rate of crystallization increases dramatically. Air drag and inertial contributions to the threadline stress become large. Under these conditions, crystallization occurs very rapidly over a small filament length and a phenomenon called neck-draw occurs (68,75,76). The molecular stmcture is stable, fiber tensde strength is adequate for many uses, thermal shrinkage is low, and dye rates are higher than traditional slow speed spun, drawn, and heat-set products (77). 

Tensile Properties. Tensile properties of nylon-6 and nylon-6,6 yams shown in Table 1 are a function of polymer molecular weight, fiber spinning speed, quenching rate, and draw ratio. The degree of crystallinity and crystal and amorphous orientation obtained by modifying elements of the melt-spinning process have been related to the tenacity of nylon fiber (23,27). 

Imagine, now, a solid held together by such little springs, linking atoms between two planes within the material as shown in Fig. 6.1. For simplicity we shall put atoms at the comers of cubes of side Tq. To be correct, of course, we should draw out the atoms in the positions dictated by the crystal structure of a particular material, but we shall not be too far out in our calculations by making our simplifying assumption - and it makes drawing the physical situation considerably easier ... 

Fig. 9.9. How single-crystal films are grown from polysilicon. The electron beam is line-scanned in a direction at right angles to the plane of the drawing.

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