Testing fiber samples from washing

Fiber samples from the washing model were also tested for antibiotic release in a zone of inhibition assay. One cm pieces of polyester were washed for various times (with buffer changes as outlined previously), sterilized, and then plated on agar streaked with S. aureus (ATCC 29213). The zone of inhibition was measured after an overnight incubation. The control sample lost antimicrobial activity within 48 hours, while the pad/heat treated polyester continued to demonstrate anti-staphylococcal activity past 336 hours (Figure 10). 

Results of histology show that PP of medically pure grade provokes only a moderate response of the tissues of the living body [5, 9, 10] as compared with PP containing traces of catalysts and stabilisers. (a) Aging of Polypropylene Fibers in vivo. PP fibers prepared from a complex thread (diameter of a thread unit = 0.033 mm) in the form of a wicker braid have been investigated. The maximal period of tests in vivo in the skin cellular tissue of a rabbit was 4 years. The samples exposed in vivo were taken from the rabbit at fixed time and washed to remove connective tissue. The... 

QF samples contained 15% (w/w) starch and 17% cellulose (Table 1). The total carbohydrate composition was 65%. Protein and oils accounted for 12%. The components measured account for 78% of the dried material, the residual material (not tested for) includes ash, extractables, lignin, and lipids. The composition of the QF was, as expected, similar to that found for corn fiber. Corn fiber and QF are both derived from the pericarp and tip portions of the kernel. Most notably, the QF contained approx the same amount of residual starch, which suggests that the modified milling process is as effective at separating starch from the pericarp as a full steeping protocol. Starch recovery is significantly improved compared to previous results for which the starch content of the QF was 42-46% w/w (2). The current study used an improved process that included an additional starch washing step. 

Samples first were washed in water with manual agitation in a Buchner funnel and then were successively rinsed with methanol, chloroform, methanol, and water. During this process, particulate debris separated from the fibers, and it was assumed that loosely attached water-, methanol-, and chloroform-soluble impurities largely washed out with the filtrate. Preliminary extraction tests for the presence of synthetic dyes were conducted as follows Samples were first boiled in water. If the solution colored, the water extract was analyzed with HPLC, and the sample was then boiled in dilute ammonia. If the ammonia extracts were strongly colored (natural dyes with the exception of very few do not extract into water or dilute ammonia), they were shaken with zinc dust, and if the ammonia extract reduced to a completely colorless solution, it was concluded that the sample was an azo dye (I). Early synthetic dyes often bleed into boiling water, and azo groups will reduce in the presence of zinc dust. 

---