Powders desirable characteristics

Figure 14-7 shows tablet data obtained by the students with their materials. It shows the strength of tablets against the compaction force used. We see that the strength of tablets of the inulin powder used here hardly depends on whether lubricant (magnesium stearate) is added or not. This is a desirable characteristic of such powders. 

To investigate the effect of different epoxidized fatty acids on the final powder coating characteristics, model compounds have been studied. If desirable, lower cross-... 

The dried vegetable products have shown the same organoleptic properties and moisture content as commercial vegetable powders for pharmaceutical use. Therefore, their active compounds do not lose their desirable characteristics after drying. 

Melt atomization processes can be classified into various categories, according to the physical properties and flow characteristics of the atomization fluid water atomization, oil atomization, and gas atomization. Gas atomization can be further classified into subsonic gas atomization, supersonic gas atomization, and ultrasonic gas atomization. The considerations in selecting a particular melt atomization method include economic factors, production scale, the physical and chemical properties of fluid to be atomized and powder to be produced, and the morphology of the powder desired [3, 5]. 

Activated carbons used in the preparation of different wines must comform to special requirements. The carbon is generally added in the powdered form in a catain ratio and should have specific properties so that it can preferentially remove certain color but does not remove components that give desired characteristics to wine. It should be able to remove undesirable components originating from mildew, cork, yeast, and so on, which may give an unpleasant taste and odor. The activated... 

SevCTal types of reactions may be employed in hydrothermal synthesis (69). A common feature is that precipitation of the product generally involves forced hydrolysis undCT elevated temperature and pressure. TTie powders have several desirable characteristics, but they also suffer from a few disadvantages so that their benefits are normally not fully realized. In hydrothermal synthesis, the crystalline phase is commonly produced directly so that a calcination step is not required, as in the case of several other synthesis routes. The powders also have the characteristics of very fine size (10-100 nm), narrow size distribution, singlecrystal particles, high purity, and good chemical homogeneity. 

The desired characteristics for an antibiotic are to have a wide antibacterial spectrum, to be an effective bactericide at low concentrations, high elution from the matrix for prolonged periods, thermal stabiHty, low allergy risks as well as low influence on the properties of the biomaterial and low serum protein binding [16,19]. Additionally, it is commonly used in the powder form. The antibiotics that implement most of these conditions are the aminoglycosides and glycopeptides. 

Small, complex-shaped glass articles such as thread guides for the textile industry and television gun mounts for the electronics industry are made by the multiform process. The dry-milled powder is mixed with an inorganic binder and a fluid vehicle, and then atomi2ed by a spray dryer into small, dried agglomerates of glass powder and binder with good flow characteristics. They are subsequently pressed to the desired shape and fired. 

Beneficiation (2,11,12,21—27) iavolves a process or series of processes whereby the chemical and/or physical properties and characteristics of raw materials are modified to render the raw material more processible. The extent of beneficiation is determined by a combination of the starting raw materials, the processiag scheme, the desired properties of the product, and economics. Powder cost iacreases with iacreased beneficiation consequently, low value-added clay raw materials used to produce iaexpensive stmctural clay products typically undergo a minimum of beneficiation, whereas higher value-added alumina powders undergo more extensive beneficiation. 

Perhaps the first practical application of carbonaceous materials in batteries was demonstrated in 1868 by Georges Le-clanche in cells that bear his name [20]. Coarsely ground MnO, was mixed with an equal volume of retort carbon to form the positive electrode. Carbonaceous powdered materials such as acetylene black and graphite are commonly used to enhance the conductivity of electrodes in alkaline batteries. The particle morphology plays a significant role, particularly when carbon blacks are used in batteries as an electrode additive to enhance the electronic conductivity. One of the most common carbon blacks which is used as an additive to enhance the electronic conductivity of electrodes that contain metal oxides is acetylene black. A detailed discussion on the desirable properties of acetylene black in Leclanche cells is provided by Bregazzi [21], A suitable carbon for this application should have characteristics that include (i) low resistivity in the presence of the electrolyte and active electrode material, (ii) absorption and retention of a significant... 

Of all these formulations, it is the diverse semisolids that stand out as being uniquely topical. Semisolid systems fulfill a special topical need as they cling to the surface of the skin to which they are applied, generally until being washed off or worn off. In contrast, fluid systems have poor substantivity and readily streak and run off the desired area. Similarly, powders have poor staying properties. Importantly, the fundamental physicochemical characteristics of solutions, liquid emulsions and suspensions, and powders are independent of their route of application, and are discussed adequately elsewhere in this text and need not be reconsidered. This is not to say the compositions of such systems cannot be uniquely topical, for there are chemicals that can be safely applied to the... 

In order to produce an adequate tablet formulation, certain requirements, such as sufficient mechanical strength and desired drug release profile, must be met. At times this may be a difficult task for the formulator to achieve, due to poor flow and compactibility characteristics of the powdered drug. This is of particular importance when one only has a small amount of active material to work with and cannot afford to make use of trial-and-error methods. The study of the physics of tablet compaction through the use of instrumented tableting machines (ITMs) enables the formulator to systematically evaluate his formula and make any necessary changes. 

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