PubMed · 9343690
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P M Debnam, D H Kohl. 1997. Variable-size injectable dialysis chambers.. https://doi.org/10.2144/97234bm28
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Cellulosic textiles, constituting over 30% of global fibre production, are biodegradable but remain challenging to recycle at scale owing to their high crystallinity, chemical finishes, and heterogeneous waste streams. Although microorganisms drive cellulose turnover in natural ecosystems, their potential for transforming anthropogenic cellulosic waste remains largely unexplored. In this study, composting was evaluated both as a sustainable approach to textile biodegradation and a reservoir of cellulolytic microorganisms with biotechnological potential. Biodegradation assays of cotton and lyocell were integrated with shotgun metagenomics and targeted cultivation to identify microbial taxa and enzymes involved in cellulose degradation. Composting trials showed that degradation was strongly influenced by both composting system and fibre composition. Community composting achieved near-complete textile disintegration, while shredded textiles exhibited the highest degradation rates, reaching up to 97%. Shotgun metagenomic revealed a bacterial-dominated community enriched in Actinomycetota and Bacillota and characterised by an abundance of glycoside hydrolases. Culture-based screening recovered 62 microbial isolates, of which Neurospora and Aspergillus exhibited the highest cellulolytic activity (>60%). In vitro assays further showed that cotton was more readily degraded than lyocell, with several isolates achieving >70% mass loss. Metagenomic approach revealed a predominantly bacterial composting community at the sampled stage, whereas cultivation preferentially recovered fungi that, despite their low relative abundance in situ, exhibited strong cellulolytic potential. These findings highlight the potential of composting as a sustainable end-of-life strategy for cellulosic textiles and identify compost microbiomes as valuable reservoirs of cellulolytic microorganisms for the development of sustainable bioprocesses for textile waste treatment.
This paper develops for the first time a concept to modify the release rate of a fixed formulation by changing only the organisation of the mix used to prepare the tablets (ordered mixing). To estimate the influence of the organisation of binary mixes, several mixes of ethylcellulose and niflumic acid of the same composition but different organisation were compacted. The tablet surfaces were examined by energy dispersive X-ray microanalysis before the release experiments. Finally, the cross-sections of the remaining matrix were examined by scanning electronic microscopy. Excipient-excipient and excipient-drug interactions are the major factors influencing the drug release rate from the tablets. In the case of interacting materials, the initial release behaviour depends on the tablet surface presented to the dissolution media. The dissolution properties of the tablets are governed by the percolating material. When the inert excipient is percolating, the release rate increases linearly with the excipient/drug size ratio, whereas when the drug is the only material percolating through the system, its release rate is independent of the size ratio. When both materials are percolating through the system, the release rate is independent of the component particle sizes.
The aims of this study were to assess the potential value of low-substituted hydroxypropylcelluloses (L-HPCs) as excipients of direct compression, and to investigate relationships between the chemical and physical properties of the polymers and (a) the powder rheological behavior and (b) drug release profiles from direct compressed tablets elaborated with (1:1) theophylline:L-HPC mixtures. Experiments were performed with five L-HPC varieties of different nominal particle sizes and degree of substitution. The products were characterized with regard to the moisture content, density, IR and Raman spectroscopy, hydroxypropyloxy content, heat of hydration, particle size, specific surface and porosity, and important differences were found in relation with all these properties. The differences in specific surface principally determine the flow and compaction properties of the powders, and the mechanical and microstructural properties of the tablets. The control of the hydroxypropyloxy content and the particle size of the L-HPCs allow the theophylline release profile to be regulated.