Semisolid pastes

VOLTAIC CELL. Two conductive metals of different potentials, in contact with an electrolyte, which generate an electric current. The original voltaic cell was composed of silver and zinc, with brine-moistened paper as electrolyte Semisolid pastes are now used electrodes may be lead, nickel, zinc, of cadmium. 

After a short reminder of the published results, we extend these in vitro experiments in vivo, and we investigate in a more detailed fashion the interaction of semisolid pastes with the skin. Emphasis was put on hydrophilic pastes, however, whenever necessary and for comparison purposes, results obtained with lipophilic pastes will be shown as well. 

Polyoxyl 40 hydrogenated castor oil occurs as a white to yellowish, semisolid paste at 20°C that liquefies at 30°C. It has a very faint characteristic odor and is almost tasteless in aqueous solution. 

Whenever you put two or more common D batteries into a flashlight, you are connecting them in series. They have to be placed in the correct order so that electrons flow through both cells. These relatively inexpensive batteries are carbon-zinc galvanic cells, and they come in several types, including standard, heavy-duty, and alkaline. This type of battery is often called a dry cell because there is no aqueous electrolyte solution a semisolid paste serves that role. Examine the cutaway view of the carbon-zinc battery in Figure 17.16 to see if you can locate the parts of the galvanic cell it contains. 

Of the many types of commercial dryers available, only a small number of important types will be considered here. The first and larger group comprises dryers for rigid or granular solids and semisolid pastes the second group consists of dryers that can accept slurry or liquid feeds. 

The composition of hpids on the surface of leaves, stems, and fruits is quite different from that of hpids that form intracellular membranes. Their role is the protection of sensitive plant tissues against the loss of water and other biologically important volatiles. Waxes (i.e., esters of FA with monofunctional alcohols) are the most important components of these lipids. Some plant waxes are of commercial importance, such as camauba or candellila wax. They are solid at room temperature and in temperate climates, with the exception of liquid jojoba wax, and are plastic or even liquid in tropical climates. They contain bound saturated long-chain FA and alcohols. Waxes on the surface of apples and other fruits from temperate zones are solids or semisolid pastes, consisting of terpenes, ceryl cerotate, ceryl palmitate, and other esters. In the wax from lettuce leaves, higher alcohols prevail, with only small amounts of free FA (Bakker et al., 1998). Other components, such as alkanes, ketones, esters, secondary alcohols, were detected in other vegetables (e.g., in kale or rutabaga). 

The aerosol product ha.s two neces.sai7 components the concentrate containing the active compound(s) and the propellant gas mixture. The concentrate can also be an emulsion, solution, or. semisolid paste, but here we restrict oui-selve.s to the suspension case in which the active compound is directly di.spensed... 

Properhes Cream semisolid paste sol. in dist. water, alcohol insol. in cottonseed oil, min. oil, propylene glycol pour pt. 33 C HLB 16.0 Atlas G-2240 [Croda Inc]... 

Uses Emulsifier for cosmetics, creams, sun protection, and baby preps. dough conditioner emulsifier in baking, dairy, confectionery, snack, maigarine, coffee whiteners. Icings, and whipped toppings Pmperties Lt. yel. semisolid paste HLB 13.1 100% cone. 

Synonyms PEG-7-PPG-isodecyl ether carboxylic acid, cetyl ester POE (7) POP (2) isodecyl ether carboxylic acid, cetyl ester Definition Cetyl alcohol ester of the carboxylic acid obtained by the oxidation of an 8-mole ethoxylate, 2-mole propoxylate of isodecyl alcohol Properties SI, yelsh. semisolid paste... 

To be semisolid, a system must have a three-dimensional structure that is sufficient to impart solidlike character to the undistributed system that is easily broken down and realigned under an applied force. The semisolid systems used pharmaceutically include ointments and solidified w/o emulsion variants thereof, pastes, o/w creams with solidified internal phases, o/w creams with fluid internal phases, gels, and rigid foams. The natures of the underlying structures differ remarkably across all these systems, but all share the property that their structures are easily broken down, rearranged, and reformed. Only to the extent that one understands the structural sources of these systems does one understand them at all. 

Colorless odorless crystals. Weapons grade material is a dark brown, thick, viscous, semisolid resembling shoe polish. It has in the past been used industrially as a wood preservative, pesticide, and herbicide for cacti. 

Poison, Class B A D.O.T. term for liquid, solid, paste, or semisolid substances other than Class A poison of irritating materials that are known or presumed on the basis of animal tests to be so toxic to man as to afford a hazard to health during transportation. 

The present chapter deals with calculations involving topical semisolid dosage forms, which include ointments, creams, and pastes. 

Pastes are also semisolid preparations intended for external application to the skin, and differ from ointments and creams in that they contain a high solid content. Pastes are made stiff by the addition of powders such as starch, zinc oxide, calcium carbonate or their mixtures. 

Ointments are semisolid preparations to be applied externally to the skin or mucous membranes they soften or melt at room temperature. Pastes are thick, stiff ointments... 

Calcium hydroxide is one of the most common causes of severe chemical eye burns. In almost all cases there is a semisolid particulate paste in contact with the cornea and conjunctiva, tending to adhere and to dissolve slowly. Strongly alkaline calcium hydroxide solution is formed and causes severe injury if not removed promptly. 

Pastes may be defined as a semisolid dosage form that contains a large proportion (i.e., 20-50%) of solids finely dispersed in a fatty vehicle (basically an ointment base) for external application to the skin. The presence of a high concentration of solids makes them much stiffer than ointments. Like ointments, pastes form an unbroken... 

Semisolid systems fulfill a special topical need by being able to cling to the surface of application. Such systems are plastic in behavior, which allows semisolids to be mechanically spread uniformly over a surface as an immobile film. For the production of lipid-free ointments, pastes, and creams, several gel-forming polysaccharides are being used. As an emulsifier they can provide a three-dimensional matrix which... 

Dewatered sludge, or filter cake, is a highly viscous material in which the remaining water is mechanically trapped within the cake. For further drying, the cake must be broken up before heating to expose as much surface area as possible. This is difficult, because semisolid filter cake often takes on the characteristics of a heavy, sticky paste when efforts are made to break it up (PACE 1986). 

Liquids and semisolids. Include oral liquids, injectable, aqueous, and oil-based liquids, emulsions, suspensions, dispersions, solutions, drops, lotions, creams, ointments, pastes, gels, liniments, aerosols and foams, suppositories, and pessaries. 

A dose of 0.5 mL of liquid or 0.5 g of solid or semisolid test chemical is applied to the site. Separate animals are not required for an untreated control group, since adjacent areas of untreated skin serve as controls for the test. The test chemical should be applied to a small area (approximately 6 cm2) of skin and covered with a gauze patch, held in place with nonirritating tape. In the case of liquids or some pastes, it may be necessary to apply the test chemical to the guaze patch and apply that to the skin. The patch should be loosely held in contact with the skin by means of a suitable occlusive dressing for the duration of the exposure period. The animals access to the patch and resultant ingestion of the test chemical by licking or by inhalation should be prevented. 

Structural adhesives that are commonly used for composites are supplied in two basic forms semisolid B-stage film and thixotropic pastes. The film adhesives are cast or extruded onto carrier fabrics or films and partially cured to a semisolid. They can easily be handled, cut, and applied to the joint area. There is no need for mixing, metering, or dispensing of liquid components. In use, these adhesive systems are activated by heat and pressure. The semisolid B-stage film liquefies briefly on application of heat and then cures to an insoluble state. Epoxy, polyimides, epoxy-nylons, epoxy-phenolic, and nitrile-phenolic adhesives are available as B-stage film. 

Creams, ointments, and pastes [17]. Creams are semisolid emulsions and are either oil-in-water or water-in-oil. Generally, the ingredients of the two phases are heated separately to 70-80°C while they are mixed and stirred vigorously to achieve emulsification. A solid ingredient can be added to the appropriate phase before emulsification or may be dispersed at some point after the emulsification step. 

---