Pellet disc

Continuous Casting Flux Copper Smelter Dust Copper Sulphite Concentrate Detergent Dust Water Sodium Silicate Sodium Silicate Water TurbulatorVDisc TUrbularor Disc Pelletizer Disc Pelletizer... 

Manganese Oxide Phosphate Rock Plastic Powder Potash Fines Sulfuric Acid Phosphoric Acid Alcohol Water TurbulatorVDisc TUrbulatorVDisc Disc Pelletizer Disc Pelletizer... 

Fig. 3.14. Pelletizing disc with re-roll ring. (Courtesy Dravo Corporation.)...

Figure 113. Movement of the charge in pelletizing discs at different rotational speeds...

Figure 114. Rotational speed n of pelletizing discs as a function of pan diameter Data points according to Klatt " ...

Figure 384. Small stainless steel pelletizing disc. (Courtesy of Erweka, Heusenstamm FRG)...

For resistivity measurements disc-shaped specimens 1.25 cm In diameter and 1.5 mm thick were Isostatlcally pressed at 7.2 kbar at room temperature. An oxygen treatment from 900°C to room temperature (100°C/hr) was used to anneal the pellet. Discs were cut Into rectangular specimens with cross sections of 1.5 x 3 mm and four leads were attached with silver paint for 4—polnt resistivity measurements. 

Blending System Paddle Mixer And Pelletiser Mixing Plant - Conditioning Drumj Mixing Drum Pelletizer Disc ... 

The FT-IR absorption spectra of the glasses in the 370-1100cmi spectral range were obtained with a JASCO FTIR 6200 spectrometer using the standard KBr pellet disc technique. The spectra were carried out with a standard resolution of 2cmri. 

Release of MB from a pellet disc made of the synthetic polymers was... 

After the MB release study, the sample was removed and air-dried to constant weight. It was then crushed to fine powder and transferred quantitatively into a flask. The volume of the suspension was adjusted to 500 mL, and 1 mL was withdrawn to determine the residual amount of MB, if any, by spectrophotometry. The flask was then warmed to 60 C to dissolve the remaining PVA derivative. The hot suspension was filtered through a Nuclepore membrane (0.2 micron porosity), and the weight of the insoluble PCL was obtained after air-Drying to constant weight. In a control experiment, pellet discs of a known PVA derivative to PCL ratio were assayed. The amount of the dissolved PVA recovered was determined by-evaporating an aliquot of the filtrate to dryness. 

Under ether anesthesia, the abdominal skin of a diabetic Wistar rat was closely shaved and swabbed with a 10% Betadine solution. A midline cut was made, and a subcutaneous pocket 3 cm from the incision was created sideways by blunt dissection. An 1/8 piece of the pellet disc containing 20% insulin was inserted and the wound was closed by two Michel clips. The whole procedure required about 3 min, and the animal recovered in less than 1 min thereafter. 

Initial tests were conducted at room temperature with pellet discs composed solely of PCL or 75%-acetate hydrolyzed PVA as the model component materials, with the amount of MB incorporated being 2.5% (w/w). It was found that the PVA pellet disc became swollen quickly and released most of the MB in 2 hrs. In contrast, the PCL pellet disc released very little even though the test was continued for over 5 days (Table 1). Changing the compression pressure during the preparation of the pellet disc to 2 or 10 tons did not alter the release characteristics as already observed. 

To facilitate the MB release by acid-catalyzed hydrolysis of PCL, the effect of maleic anhydride was tested. It was found that a small amount of the anhydride drastically increased the initial release rate of MB (Table 2) and depleted the dye in a few hours. However, analyses of the pellet disc after 1 week showed that the same amount of PCL used was left. Apparently the anhydride, if any remained therein, did not enhance the hydrolysis of PCL, as intended. The content of maleic anhydride which gave the slowest initial MB release was about 5% (w/w). Since acid catalysis did not occur, the addition of maleic anhydride was not studied further. 

Table 1. Methylene blue dye released of a single polymer. from pellet discs made...

When the pellet discs were again analyzed after the experiment, it was found that the weight of PCL remaining closely approximated the weight of PCL put in the original discs. This occurred over several compositions of the PVA/PCL used, regardless of the duration of MB release. 

Table 4. Effect of PVA deacetylation on MB release from pellet discs containing 80% PCL.

Around pH 6-7, insulin is essentially insoluble in water, and indeed very little protein was detected after 30 days in the in vitro run from the 1/4 piece of the pellet disc made of palmitic acid containing 20% insulin. However, at pH 2.4 insulin is readily soluble, and another 1/8-size piece assayed in the 0.1 M orthophosphate solution showed that close to 60% (i.e., c, 3 mg) of the protein content was released in about 14 days (Table 6). As guided by these release studies observed in vitro, it... 

From a 25 mg piece cut from the 200 mg pellet disc containing 20% insulin. 

Implanted as 1/8 size piece cut from a 200 mg pellet disc. 

However, the data revealed several interesting characteristics of a combined matrix system. Firstly, it was found that an additive such as maleic anhydride could facilitate the release of MB from the otherwise seemingly impermeable PCL matrix without erosion by ester hydrolysis. Secondly, as indicated by MB release and analyses of the composition, at 20% by weight or less, a polymeric component of low solubility, such as partially hydrolyzed PVA, could be released from a PCL pellet disc which did not erode and acted as a passive structural component. Finally, the passive component could essentially be selected from any compound, polymeric or otherwise, as well as being permanently or even temporarily insoluble. Therefore, it was inferred that a bioactive polypeptide like insulin or somatotropin could also be safely delivered on a sustained basis from an implant made of a passive structural component as aforementioned. 

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