Wagon wheels

Fig. 13. Examples of pipe gas distributors (a) simple sparger, (b) details of the pipe, (c) wagon wheel, and (d) multilevel distributor.

A plethora of reactions has been reported for the in situ generated (OC)5W=PPh, many of which have been the topic of previous reviews [2-4]. A typical account of the versatility of this reagent with olefinic and acetylenic bonds is visuaHzed in the wagon wheel . Only a brief account with selected ex-... 

Sphere> pellet > trilobe > hollow extrudate > wagon wheel/ minilith The definitive catalyst size selection will be a compromise between high reaction rate (small partiele, exotic shape), low pressure drop (large particle, exotic shape), large crushing strength... 

The carrier can be in the form of a powder used for slurry reactions or a particulate such as a sphere, cylinder, or tablet (typically a few mm in diameter) used in fixed bed reactors. The size and shape depend very much on what is anticipated to be the rate-limiting step. For example, for a reaction limited by pore diffusion it is customary to use a smaller particle in the shape of a star, trilobe, or wagon wheel to decrease the diffusion path while increasing the external geometric surface area. Mechanical strength and solubility... 

Figure 34. "Wagon Wheel primary reforming catalyst (UC1)...

Katalco), a six-shooter configuration (Topsoe), and a wagon-wheel shape (United Catalysts Inc. Fig. 34). 

Figure 13.7 Transmission electron micrographs of a thin-sectioned PS-PI block copolymer gyroid phase (a) sectioned at an orientation showing the wagon-wheel three-fold projection of the cubic structure thi sectioned at an orientation showing the four-fold projection. (Reprinted with permission from Forster et al., Macromolecules 27 6922. Copyright 1994, American Chemical Society.)...

The structures labeled (w, and w )-TiO on Pt(l 11) correspond to three hexagonal wagon-wheel structures found by LEED and STM. The w phase grows under oxidizing conditions, the w phase is produced by exposing the w phase to reducing conditions, and the w. appears as an intermediate phase between these conditions which always coexists with at least one of the other w phases. 

Before Nobel began studying the explosive properties of nitroglycerin, people reportedly used the compound for everyday chores, such as polishing boots and greasing wagon wheels, and even as lamp... 

Another type of reconstruction that is commonly foimd after film growth on Pt(l 11) is the so-called wagon-wheel pattern. This particular reconstruction is found for example with Cr/Pt(l 11) [57,58] and Ce/Pt(l 11) [59,60] and also for various oxide films (see below). Another example of temperature control of the pattern is found in the case of Ti on W(IOO) where a square nanomesh with a lattice constant of 4.5 nm can be produced by annealing at 1370 K [61]. 

Recently well-ordered Ti02 films on Pt(l 11) have attracted some attention and have been exploited as growth templates. The z -TiOx (zigzag-hke) phase has been shown to act as a template for the nanostructured growth of Au islands at RT [197], in marked contrast to the so-called V-TiOx (wagon-wheel-hke) phase, which is nanostructured but does not act as a template. 

Operator-based maintenance began with the entrepreneurial spirit of the cottage industry in the U.S. free enterprise system. In most cases, the owners fixed the sawmills, the cotton gins, the printing presses, and the wagon wheels. Owners were the skilled crafts people working within a free enterprise culture and system. For many Americans, OEM started with Henry Ford s Model T, which came with tools—a crescent wrench, slip-joint pliers, screwdriver, and hammer, and so on—for the do-it-yourself repairs. 

Residual stresses can also arise if a hole is drilled, with a blunt bit, through a product that is initially stress-free. The drilling operation generates enough heat to melt a thin annulus of plastic surrovmding the hole. When this cools down, it contracts, so has a residual tensile circiunferential stress (the effect is the converse of shrink-fitting a metal rim on a wooden wagon wheel). Consequently, cracks may start in a radial direction, but they will turn to follow the boundary of the overheated layer. These two examples show that the crack patterns can reveal the type of residual stress field in a product. 

In places their wagon wheels carved ruts shoulder-deep in the rocky road. 

Variation of pultrusion producing continuously reinforced products other than profiles. By pulling fibers through a rotation wagon-wheel-type die, curved shapes are formed. Recirculating molds which clamp around the wet fiber package allow continuous forming of various shapes. 

B.C.E. Wheel The chariot wheel and the wagon wheel evolve—possibly from the potter s wheel. One of humankind s oldest and most important inventions, the wheel leads to the invention of the axle and a bearing surface. 

Fig. 26 TEM micrograph of poly(isoprene-bZocfc-vinylpyridine) diblock copolymer. Due to OSO4 staining, isoprene-rich regions are electron-opaque and appear dark. The wagon wheel projection associated with the [111] axis of G morphology is observed...

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