Gel powders

The vibrational overtones and combinations of hydroxyl groups and thek associated molecular water occurring in the spectra of various gel siUca materials are summarized in Table 2 and discussed in References 3, 5, and 22. These peaks and bands found in the preparation of alkoxide-derived siUca gel monoliths are identical to those described for siUca gel powders (41). 

Sol-Gel Techniques. Sol-gel powders (2,13,15,17) are produced as a suspension or sol of coUoidal particles or polymer molecules mixed with a Hquid that polymerizes to form a gel (see Colloids SoL-GELtechnology). Typically, formation of a sol is foUowed by hydrolysis, polymerization, nucleation, and growth. Drying, low temperature calciaation, and light milling are subsequently required to produce a powder. Sol-gel synthesis yields fine, reactive, pseudo-crystalline powders that can be siatered at temperatures hundreds of degrees below conventionally prepared, crystalline powders. 

Oral Tablets, capsules, solutions, syrups, gels, powders... 

After the production of the solution of proteins, the purification of the protein requires six different steps. Silica gel powder is added to the solution and filtered off, to adsorb large quantities of cytochrome C3. Several steps of column chromatography follow. 

Microamorphous sihca is made of particles with diameters less than 1pm. They have very high surface areas, usuady greater than 3m2/g. These microamorphous sihca are an aggregation of colloidal ultimate particles that broadly include sols, gels, powder, and porous glass. An important class of... 

Silica gel is an amorphous, highly porous, partially hydrated form of silica, which is a substance made from the two most abundant elements in the Earth s crust silicon and oxygen. Silica gel powder is widely used in industries for catalyst support as adsorbents,... 

Tolnaftate (Aftate, Tinactin, and others) is available in a 1% concentration as a cream, gel, powder, aerosol powder, and topical solution, or as a topical aerosol liquid. 

Figure 6 shows the amounts of PMMA adsorbed onto silica gel powders from six solvents of known basicity or acidity, chosen from Drago s tables. Carbon tetrachloride was the most neutral solvent, benzene a very weak base, and dioxane and... 

Pre-HPLC Column Chromatography. Five grams of 60-200 mesh silica gel powder (4.7% weight lost on ignition) supplied by J. T. Baker Chemical Company were poured into a 10 mm i.d. glass column. The concentrated extract redissolved in 10 ml methylene chloride was transferred to the column and allowed to soak into the silica gel. Then 65 ml of additional methylene chloride were added to the column. The first 10 ml of the eluate were discarded, and the next 50 ml collected in a 125 ml Erlenmeyer flask. 

Immobilized HRP in a sol-gel conventional SBA-15. The immobilized Hb retained 80% of its activity A microsized gel powder was prepared [35]... 

Fine ceramic powders made by spray drying, by sol-gel powder synthesis, and sometimes by precipitation usually have very low packing densities. A possible reason for these low packing densities is that the basic packing units are porous agglomerates. In sol-gel s3mthesis. 

Similar investigations of the mechanochemical synthesis of zircon using anhydrous and sol-gel powders of zirconium and silicon oxides as initial reagents were reported in [43,44]. 

Formulation and dosage form aspects that can impact the site of deposition within the nasal cavity are a key consideration for nasal delivery. The site of deposition can impact absorption due to the differences in the permeability and residence time of the anterior and posterior portions of the nose. A variety of dosage forms such as nasal drops, sprays, gels, powders, or microspheres are available for administering pharmaceuticals by the nasal route, and these options need to be carefully evaluated because the type of dosage form can impact where the formulation is deposited in the nasal cavity and, in turn, the systemic absorption. For example, the bioavailability of nasally administered desmopressin was significantly increased in a spray formulation compared with drops, " likely... 

Gel preparations Some Japanese investigators are promoting the use of jellylike preparations to help elderly patients overcome their difficulty in swallowing conventional tablets and capsules (189-191). These dosage forms rely on gelation of materials such as sodium casseinate, glycerogelatin, dried gelatin gel powder, and silk fibroin. 

Tig. 4. Pyridine vapor adsorbed in vacuo on a silica gol disk at different pressures. Curve 1 0.8 curve 2 1.4 curve 3 8.3 curve 4 17.0 mm Hg curve 5 pyridine adsorbed on silica gel powder from cyclohexane (immersed in Nujol). Prom Okuda (4Sa). The scale on the right is for the dashed curve. 

The used catalysts were pure and mixed semiconductor and insulator powders of various sources. Two SiO catalysts were prepared by contacting for one week silica gel powders with HF or with NaOH aqueous solutions, whose pH values were 3 and 10, respectively. 

Sanogran . [Sandoz] Pigmnits for coloring gels, powders, and solids. 

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