Wetted powders

The paste-extmsion process includes the incorporation of ca 16—25 wt % of the lubricant (usually a petroleum fraction) the mixture is roUed to obtain uniform lubricant distribution. This wetted powder is shaped into a preform at low pressure (2.0—7.8 MPa or 19—77 atm) which is pushed through a die mounted in the extmder at ambient temperature. The shear stress exerted on the powder during extmsion confers longitudinal strength to the polymer by fibrillation. The lubricant is evaporated and the extmdate is sintered at ca 380°C. 

While two operators were charging penicillin powder from fiber drums into a reactor containing a mixture of acetone and methanol, an explosion occurred at the reactor manhole. The two operators were blown back by the force of the explosion, and were covered with solvent-wet powder. 

In preparing any of the above for use in columns, the dry powder is evacuated, then mixed under reduced pressure with water or the appropriate buffer solution. Alternatively it is stirred gently with the solution until all air bubbles are removed. Because some of the wet powders change volumes reversibly with alteration of pH or ionic strength (see above), it is imperative to make allowances when packing columns (see above) in order to avoid overflowing of packing when the pH or salt concentrations are altered. 

Use of solutions, slurries, pellets, granules or dust-free (i.e. partially-wetted) powders instead of dry powders. 

Precipitated, washed and filtrated hydroxides consisting of wet powder contain two kinds of water. The first is moisture, i.e. water remainders that include adsorbed water. This kind of water can be successfully removed by diying at 100-200°C. The second type is molecules of water that are incorporated with tantalum or niobium to form hydroxides. Because hydroxyl groups form relatively strong bonds with tantalum or niobium, the separation of the second kind of water requires thermal treatment at higher temperatures [501],... 

Directions for reconstitution Tap bottle until all powder flows freely. Add approximately 2/3 of the 90 mL of water shake vigorously to wet powder. Add remaining water and shake vigorously again. 

A surfactant is a surface-active agent that is used to disperse a water-insoluble drug as a colloidal dispersion. Surfactants are used for wetting and to prevent crystal growth in a suspension. Surfactants are used quite extensively in parenteral suspensions for wetting powders and to provide acceptable syringability. They are also used in emulsions and for solubilizing steroids and fat-soluble vitamins. 

Dry and grind the top of the cactus and add 50 g to 250 ml methanol and let soak one day. Filter and add 100 ml IN HC1 to the wet powder and let stand about two hours. Meanwhile, evaporate in vacuum the methanol. Filter the HC1 solution until clear and add to the residue remaining from the methanol. Make pH about 7 with 2N KOH and add 100 ml CHC13. Shake in separatory funnel and separate the bottom CHC13 layer. Add 40 ml water to the CHCI3 and shake in separatory funnel. Dry and evaporate in vacuum the CHC13 layer to get the mescaline (and other compounds). 

The human skin model assay involves measuring the effects of corrosives on viable cells in a reconstituted human skin equivalent. To be accepted as a valid human skin model, several criteria must be met. The artificial skin must comprise a functional stratum corneum with an underlying layer of viable cells. Furthermore, the barrier function of the stratum corneum, as well as the viability of the epidermis, must be verified with appropriate experimental setups. The chemicals to be tested are applied up to 4 h as a liquid or a wet powder onto the skin model. Afterwards, careful washing has to be performed, followed by investigation of the cell viability [e.g., with a (MTT)] reduction assay). 

The application of neutron spin-echo spectroscopy to the analysis of the slow dynamics of biomolecules is still in its infancy, but developing fast. The few published investigations either pertain to the diffusion of globular proteins in solution [332-334] or focus on the internal subnanosecond dynamics on the length scale, <10 A as measured on wet powders [335,336]. The latter regime overlaps with other quasi-elastic neutron scattering methods as backscattering and TOE spectrometry [337-339]. 

Harrison PJ, Newton JM, Rowe RC. The characterization of wet powder masses suitable for extrusion/spheronization. J Pharm Pharmacol 1985 ... 

Fielden KE, Newton JM, Rowe RC. A comparison of the extrusion and spheronization behavior of wet powder masses processed by a ram extruder and a cylinder extruder. Int J Pharm 1992 81 225-233. 

Schindler, J., Meyer-Olbersleben, F., Kirbach, B., (1998), Fabrication of FGM-foils for joining application by wet powder spraying , presented at 5th International Symposium on Functionally Graded Materials, Dresden, October 1998. 

Upon contact of silica with a nickel nitrate ammo-niacal solution, one observes that the purple blue colour, characteristic of nickel hexaammine [Ni(NH3)6]2+, is transferred from the solution to the silica support, while the diffuse reflectance of the resulting wet powder is the same as that of the initial solution. These phenomena can be explained in terms of the following competitive cation exchange, where ammonium ions compete with nickel hexaammine complexes to occupy the =SiO exchange sites of silica ... 

Samples used for ohtaining x-ray diagrams were ground in benzene and specimens were prepared hy mixing the wet powder with Canada balsam in xylene solution. 

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