Compressible mixtures

The feldspars are aluminosilicates in which as much as half the silicon(IV) has been replaced by aluminum(III). They are the most abundant silicate materials on Earth and are a major component of granite, a compressed mixture of... 

FIGURE 14.41 The mineral granite is a compressed mixture of mica, quartz, and feldspar. 

In the 1930s, Bone et al. [15] using rotating mirror camera observed the action of shock waves propagating into the unburnt mixture ahead of the accelerating flame, and postulated that the detonation wave was initiated as a result of preignition of the shock-compressed mixture. 

In its simplest form, the gas turbine consists of a compressor and a turbine (or an expander). In a single-shaft gas turbine, these are mechanically connected and are rotating at the same speed, as shown in Figure 23.13a. Air from ambient is compressed and raised in temperature as a result of the compression. A portion of the compressed air enters a combustion chamber where fuel is fired, and the temperature of the gases is raised further to a temperature in excess of 1500°C. Some of the air from the compressor provides cooling for the combustor walls. The hot, compressed mixture of air and combustion gases then flows to the inlet of the turbine. In the turbine, the gas... 

AM Healy, OI Corrigan. Predicting the dissolution rate of ibuprofen-acidic excipient compressed mixtures in reactive media. Int J Pharm 84 167-173, 1992. 

The combustion of compressed mixtures of the polymer with the finely powdered elements under nitrogen or argon has been studied, reactivity decreasing in the order B, Mg, Ti. 

Ignition of a compressed mixture, applied as a 6 mm layer on electronic components generates enough heat effectively to destroy them. 

Combustion of compressed mixtures of metal powder and the oxide is very vigorous, a layer of molten aluminium being produced initially, followed by a jet of flame. 

Fluorocarbon polymers Kirk-Othmer (3rd ed.), 1982, Vol. 19, 495 Compressed mixtures are used as special igniters. 

Mixtures of the nitrate with powdered aluminium or its oxide (the latter seems unlikely) were reported to be explosive [1], and the performance characteristics of flares containing compressed mixtures of the metal and nitrate have been evaluated [2]. A violent explosion in a copper smelting works was caused mainly by reaction of aluminium with sodium nitrate [3],... 

The use of parallel beam optics as a means for determining the polymorphic composition in powder compacts has been discussed [45]. In this study, compressed mixtures of known polymorphic composition were analyzed in transmission mode, and the data were processed using profile-fitting software. The advantage of using transmission, rather than the reflectance, is that the results were not sensitive to the... 

Direct Oxidation. Direct oxidation of petroleum hydrocarbons has been practiced on a small scale since 1926 methanol, formaldehyde, and acetaldehyde are produced. A much larger project (29) began operating in 1945. The main product of the latter operation is acetic acid, used for the manufacture of cellulose acetate rayon. The oxidation process consists of mixing air with a butane-propane mixture and passing the compressed mixture over a catalyst in a tubular reaction furnace. The product mixture includes acetaldehyde, formaldehyde, acetone, propyl and butyl alcohols, methyl ethyl ketone, and propylene oxide and glycols. The acetaldehyde is oxidized to acetic acid in a separate plant. Thus the products of this operation are the same as those (or their derivatives) produced by olefin hydration and other aliphatic syntheses. 

The original concept was that precompression would allow a more gradual escape of air from the granulation or direct compression mixture. It was believed by some that the entrapment of air in the compact, due to the rapid and forceful compaction, would result in capping and lamination of the tablet. Although this might be a minor consideration, it does not seem to be the most important reason for such tablet defects. 

It is obvious that most of the effects of scale-up are seen in the unit operations that occur before compressing, especially blending, granulation, milling, and drying. These operations impart the important physical properties to the mixture to be compressed. For example, separation of particle sizes in the hopper would be a function of the choice of excipients or the processing steps to get to the final granulation or direct compression mixture. 

The cathode mix is a compressed mixture of electrolytic Mn02 (EMD) and synthetic graphite or acetylene black to provide electronic conductivity, in a ratio of 4—5 1, wetted with electrolyte. The cathode current collector is generally the external steel can, which may be nickel-plated or coated with conductive carbon. Reduction of Mn02 in alkaline conditions is a complex process and follows a number of steps which can be written formally as... 

The feldspars are aluminosilicates in which up to half the Si44 ions have been replaced by Al3+ ions. They are the most abundant silicate materials on Earth and are a major component of granite, a compressed mixture of mica, quartz, and feldspar (Fig. 14.45). When some of the cations between the crystal layers are washed away as these rocks weather, the structure crumbles to clay, one of the main inorganic components of soil. A typical feldspar has the formula KAlSi3Og. Its weathering by carbon dioxide and water can be described by the equation... 

Germans used a mine explosive consisting of 56 per cent potassium perchlorate, 32 per cent dinitrobenzene, and 12 per cent dinitronaphthalene.48 Their Tri-Trinal for small-caliber shells was a compressed mixture of 2 parts of TNT (Tri) with 1 of trinitronaphthalene (Trinal), and was used with a booster of compressed picric acid. 

A. T. Larson and C. A. Black found that the cone, of ammonia by vol. in a compressed mixture of hydrogen and nitrogen over liquid ammonia increases with increasing temp, from —22-5° to 10°, and decreasing press, from 1000 to 50 atm. There is a definite equilibrium, and the values for ammonia are greater than those calculated from the vap. press, of liquid ammonia. 

Finally the plate is tested on heat expansion coefficient, temperature shock resistance, temperature stress (6,000 hours at 650°C), density, E-modulus (92 x 103 N/mm2), flexural strength, impact resistance, Knoop hardness, acid and base resistance. The heating element is insulated with a compressed mixture of powder and fibre which contains aluminium oxide and silicon oxide. In the middle the element contains a so-called Stabausdehnungsbegrenzer (= expansion limiter), which automatically switches the element off in case the temperature exceeds a certain pre-set value. 

Under some operating conditions, sufficient pressure differential may exist across the valve to cause the vena contracta pressure to drop to the saturation pressure (also known as the vapor pressure) of the liquid. If this occurs, a portion of the liquid will vaporize, forming a two-phase, compressible mixture within the valve. If sufficient vapor forms, the flow may choke. When a flow is choked, any increase in pressure differential across the valve no longer produces an increase in flow through the valve. 

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