Range of sizes

Levy L et al 1997 Three dimensionally diluted magnetio semioonduotor olusters CdMnS with a range of sizes and oompositions dependenoe of speotrosoopio properties on the synthesis mode J. Phys. Chem. B 101 9153... 

A number of attempts have been made to demonstrate the connection between mesoporosity and the Type IV isotherm by comparing the isotherm of a vapour on a nonporous powder before and after it has been formed into a compact. The process of compaction produces pores in the form of interstices between the particles of the original powder such pores will tend to have dimensions of the same order as those of the constituent particles, and it can be arranged that these shall fall within the mesopore range of size. 

Examples of the application of size-exclusion chromatography to the analysis of proteins. The separation in (a) uses a single column that in (b) uses three columns, providing a wider range of size selectivity. (Chromatograms courtesy of Alltech Associates, Inc. Deerfield, IL). 

Coarse bubble systems are typically found with orifice, perforated disks, or pipe spargers. Under most reaUstic conditions, bubbles of about 4—6 mm are formed. Eor a wide range of sizes... 

In addition, because of the extreme variation in the bulk density of products, use of the standard 19-L (5-gal), 38-L (10-gal), 61-L (16-gal), 114-L (30-gal), and 208-L (55-gal) metal dmms often results in excessive outage. Fiber dmms, in contrast, are available in a wide range of sizes, and can be sized to meet product volumes, thus allowing for Httle outage as weU as saving storage and shipping space. 

A recent trend in particle analysis has been the introduction of personal computer-based automation (3). Sophisticated software packages can be used to automate and speed up the analysis. In some cases these computers can even carry out continuous process control (qv) (see Computer technology). The latest machines also allow the measurements of smaller particles and can detect a wider range of sizes. Machines based on light-scattering principles are being more widely accepted by the industry because of speed. An average analysis takes from 1—2 min, whereas those based on sedimentation principles require from 10—120 min. 

Catalyst Particle Size. Catalyst activity increases as catalyst particles decrease in size and the ratio of the catalyst s surface area to its volume increases. Small catalyst particles also have a lower resistance to mass transfer within the catalyst pore stmcture. Catalysts are available in a wide range of sizes. Axial flow converters predorninanfly use those in the 6—10 mm range whereas the radial and horizontal designs take advantage of the increased activity of the 1.5—3.0 mm size. 

Experimental exponents for cake thickness vary from 0.5 to as much as 3.0. The theoretical value of //2 may be approached only by incompressible cakes of a narrow range of sizes. The proper and characteristic value for the mean particle size, d, is difficult to ascertain. In practice, the most finely divided particles, eg, 10—15 wt % of soHds, almost whoUy determine the Hquid content of a cake, regardless of the rest of the size distribution. It seems reasonable to use a d closely related to Hquid content, eg, the 10% point on a cumulative weight-distribution curve. 

The effect of the ahoying elements on AISI steels is indirect because ahoying elements control microstmcture through their effect on hardenabhity. These elements permit the attainment of desirable microstmctures and properties over a much wider range of sizes and sections than is possible with carbon steels. 

Nonabsorbable Natural Sutures. Cotton and silk are the only nonabsorbable sutures made from natural fibers that are stiH available ia the United States. Cotton suture is made from fibers harvested from various species of plants belonging to the genus Gossipium. The fiber is composed principally of ceUulose. The seeds are separated from the cotton boUs, which are carded, combed, and spun iato yams that are then braided or twisted to form sutures ia a range of sizes (Table 4). The suture is bleached with hydrogen peroxide and subsequendy coated (finished or glaced) with starch and wax. The suture may be white or dyed blue with D C Blue No. 9. 

Silk (qv) suture is made from the threads spun by the silkworm Bombjx mori. The fiber is composed principally of the protein fibroin and has a natural coating composed of sericin gum. The gum is usually removed before braiding the silk yams to make sutures in a range of sizes. Fine silk sutures may be made by simply twisting the gum-coated silk yams to produce the desired diameter. White silk is undyed. Silk is either dyed black with logwood extract or blue with D C Blue No. 9. The suture may be uncoated or coated either with high molecular weight polydimethylsiloxane or with wax. 

Braided Synthetic Nonabsorbable Sutures. Braided synthetic nonabsorbable sutures are made by melt-spinning thermoplastic polymers into fine filaments (yams), and braiding them, with or without a core, to form multifilament sutures in a range of sizes. Nylon-6,6 [32131 -17-2] (7) is a polyamide produced by the condensation polymerization of adipic acid and 1,6-hexanediamine. 

The centrifugal pump is the type most widely used in the chemical industiy for transferring liquids of aU types—raw materials, materials in manufacture, and finished produc ts—as well as for general services of water supply, boiler feed, condenser circulation, condensate return, etc. These pumps are available through avast range of sizes, in capacities from 0.5 mVh to 2 X 10 mVh (2 gal/min to 10 gaJ/min), and for discharge heads (pressures) from a few meters to approximately 48 MPa (7000 Ibf/iu"). The size and type best suited to a particular apphcation can be determined only by an engineering study of the problem. 

CViemical Ware Acidproof chemical-stoneware pipe and fittings withstand most acid, alkah, or other corrosives, the main exception being hydrofluoric acid. The range of sizes made with the bell-and-spigot joint and with plain butt ends is shown in Table 10-40. 

These devices are replacing the older tank and spiral-conveyor devices. Better provisions for speed and ease of fill and discharge (without powered rotation) minimize downtime to make this batch-operated device attractive. Heat-transfer coefficients ranging from 28 to 200 W/(m °C) [5 to 35 Btu/(h fF °F)] are obtained. However, if caking on the heat-transfer walls is serious, then values may drop to 5.5 or 11 W/(m °C) [1 or 2 Btu/(h fH °F)], constituting a misapplication. The double cone is available in a fairly wide range of sizes and construction materials. The users are the fine-chemical, pharmaceutical, and biological-preparation industries. 

There are numerous machines and machine types to obtain a number of different particle-size classes from sohds having a full range of sizes, and there is much overlapping in the possibihties. Usually, one type will provide optimum economy for the specific problem involved. 

Simple and relatively efficient separation. Normally a two-product device but may be operated in series to give a range of size fractions. 

The breakage function AB gives the size distribution of product breakage of size u into all smaller sizes k. Since some fragments from size u are large enough to remain in the range of size u, the term AB is not zero, and... 

Considering the wide range of sizes of automotive engines, do you feel that an emission standard in gm km" rather than g m" or ppm is equitable to all automobile manufacturers ... 

Welded or seamless tubing manufactured in a large range of sizes of varied chemical compositions (sizes range V16-IO % in. o.d. inclusive for carbon and alloy material) usually not fabricated to meet any specification other than application requirements fabricated to meet exact outside diameter and decimal wall thickness. 

Smoke pellets are produced in a range of sizes and are commonly used tor the resting of household flues and chimneys. The pellet is ignited and will burn for about 10 seconds producing a dense white smoke. Because this is a combustion process there are obvious restrictions on its use (nonflammable atmo spheres, nonflammable surfaces, etc.). In addition the smoke is buoyant because of the heat generated. The smoke can also be an irritant and/or toxic. The production of smoke cannot be controlled, but pellets are inexpensive, easy to use, and readily available, and the smoke is produced in sufficient quantities to make them useful in the evaluation, for example, of fume cupboards and Ixroths. 

Ouchyama, N. and Tanaka, T., 1981. Porosity of a mass of particles having a range of sizes. Industrial and Engineering Chemistry Eundamentals, 20, 66-71. 

The resolution required in any analytical SEC procedure, e.g., to detect sample impurities, is primarily based on the nature of the sample components with respect to their shape, the relative size differences of species contained in the sample, and the minimal size difference to be resolved. These sample attributes, in addition to the range of sizes to be examined, determine the required selectivity. Earlier work has shown that the limit of resolvability in SEC of molecules [i.e., the ability to completely resolve solutes of different sizes as a function of (1) plate number, (2) different solute shapes, and (3) media pore volumes] ranges from close to 20% for the molecular mass difference required to resolve spherical solutes down to near a 10% difference in molecular mass required for the separation of rod-shaped molecules (Hagel, 1993). To approach these limits, a SEC medium and a system with appropriate selectivity and efficiency must be employed. 

---