Powder group

Powder(s). See also Amorphous silicate powders Group A powders... 

C. E. Waller was another creative member of the unusual Trojan Powder group of the post-World War I era. His patents covered the improvement of starch nitrate compositions. 

Fluon Polytetrafluoroethylene, Isostatic Compaction of PTFE Powders, Technical Service Note F 14, Molding Powders Group, ICI Plastics Division, Welwyn Garden City, U.K. (Aug. 1973)... 

High-fat diet plus 5% oolong tea powder-group 0.67 2.12 49.8... 

Group 1 consists of 5 compositions of a mixture of AlN-powder and pure Cr-powder. Group 2 consists of 5 compositions of a Al- and CrjN -powder mixture. Group 3 is two different mixtures of AIN and CrjN -powders. Group 4 consists of two different compositions of Al- and Cr-powders. Table I shows the molar compositions of the different samples. 

Fig. 129.6 Representative histopathology of H E stained colorectal tissue sectiwis (a) control group fed with a standard diet (b) control group + tomato powder fed with a standard diet +5 % tomato powder (c) AOM-treated group fed with a standard diet (d) AOM + tomato powder group fed with a standard diet +5 % tomato powder (x400 magnification) [151]...

What are the chief behaviour characteristics of the four Geldart powder groups ... 

Figure 10.4 shows illustrative examples of this relation for the four powder groups - A, B,C and Z) - of the Geldart classification for ambient air fluidization. Figure 10.1. 

ARUN KUMAR CHATTOPADHYAY United States Bronze Powders Group of Companies, Haskell, New Jersey, U.S.A. 

Gattermann s reaction A variation of the Sandmeyer reaction copper powder and hydrogen halide are allowed to react with the diazonium salt solution and halogen is introduced into the aromatic nucleus in place of an amino group. 

A few illustrative examples are the following. Photohydrogenation of acetylene and ethylene occurs on irradiation of Ti02 exposed to the gases, but only if TiOH surface groups are present as a source of hydrogen [319]. The pho-toinduced conversion of CO2 to CH4 in the presence of Ru and Os colloids has been reported [320]. Platinized Ti02 powder shows, in the presence of water, photochemical oxidation of hydrocarbons [321,322]. Some of the postulated reactions are ... 

Acetaldehyde and also many ketones, such as acetone, containing the CH3CO-group behave similarly when treated with bleaching powder, chlorination of the CHsCO - group being immediately followed by fission of the molecule by the alkali present in the bleaching powder ... 

A halogen atom directly attached to a benzene ring is usually unreactive, unless it is activated by the nature and position of certain other substituent groups. It has been show n by Ullmann, however, that halogen atoms normally of low reactivity will condense with aromatic amines in the presence of an alkali carbonate (to absorb the hydrogen halide formed) and a trace of copper powder or oxide to act as a catalyst. This reaction, known as the Ullmant Condensation, is frequently used to prepare substituted diphenylamines it is exemplified... 

Use approximately 0-5 g. of the finely powdered anhydrous glucose, heating for 60 minutes. Slightly low results (e.., 4-7-4 8 Hydroxyl groups) are usually obtained. 

Lithium aluminium hydride LiAlH is a useful and conveuient reagent for the selective reduction of the carbonyl group and of various other polar functional groups. It is obtained by treatment of finely powdered lithium hydride with an ethereal solution of anhydrous aluminium chloride ... 

The methylthio group is removed by treatment with zinc powder in HCl (276) to give the 2-unsubstituted thiazole. The action of aluminum-mercury amalgam in methanol on various thioethers is reported to yield the expected thiazole (108) when Rj is an alkyl group and the corresponding A-4-thiazoline-2-thione (109) when Rj PhCH - (Scheme 55) (169). 

Product from melt or suspension treatment is obtained directly as emmb or powder. Polymer recovered from solution treatment is obtained by precipitative cooling or spray drying. Polymer with now stable end groups may be washed and dried to remove impurities, especially acids or their precursors, prior to finishing operations. 

Prices for the different material groups (F —F ) are largely influenced by product size and shape and the quantity of production. Apart from product shape, the main price-determining factor is the performance factor K Prices for the powder, a sintered anisotropic ring, and a sintered anisotropic segment are roughly on the order of 1, 2, and 5, respectively. 

Geldart a group Powder Average particle size, (, )J.m Particle density, p, kg/m Angles Internal friction, deg of Repose, deg Sphericity, f... 

The maximum bubble size for Group A powders is of great significance for design. The single most important parameter controlling bubble size is... 

Classical bubbles do not exist in the vigorously bubbling, or turbulent fluidization regimes. Rather, bubbles coalesce constantly, and the bed can be treated as a pseudohomogenous reactor. Small bubble size improves heat transfer and conversion, as shown in Figure 5b. Increasing fines levels beyond 30—40% tends to lower heat transfer and conversion as the powder moves into Group C. 

Fig. 8. (a) Schematic for an FCC unit showing where the various fluidization regimes are found and (b) a corresponding phase diagram for Group A powder (FCC catalyst) where the numbers on the curves represent the superficial soHd velocity in m/s. A represents the bubbling regime B, the turbulent ... 

Bubbles and Fluidized Beds. Bubbles, or gas voids, exist in most fluidized beds and their role can be important because of the impact on the rate of exchange of mass or energy between the gas and soflds in the bed. Bubbles are formed in fluidized beds from the inherent instabiUty of two-phase systems. They are formed for Group A powders when the gas velocity is sufficient to start breaking iaterparticle forces at For Group B powders, where iaterparticle forces are usually negligible, and bubbles form immediately upon fluidization. Bubbles, which are inherently... 

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