ABSTRACT
A fungal biorefinery is presented to valorize food waste to fungal monofilaments with tunable properties for different textile applications. Rhizopus delemar is successfully grown on bread waste and the fibrous cell wall is isolated. A spinnable hydrogel is produced from cell wall by protonation of amino groups of chitosan followed by homogenization and concentration. Fungal hydrogel is wet spun to form fungal monofilaments which underwent post-treatments to tune the properties. The highest tensile strength of untreated monofilaments is 65 MPa (and 4% elongation at break). The overall highest tensile strength of 140.9 MPa, is achieved by water post-treatment. Moreover, post-treatment with 3% glycerol resulted in the highest elongation % at break, i.e., 14%. The uniformity of the monofilaments also increased after the post-treatments. The obtained monofilaments are compared with commercial fibers using Ashby's plots and potential applications are discussed. The wet spun monofilaments are located in the category of natural fibers in Ashby's plots. After water and glycerol treatments, the properties shifted toward metals and elastomers, respectively. The compatibility of the monofilaments with human skin cells is supported by a biocompatibility assay. These findings demonstrate fungal monofilaments with tunable properties fitting a wide range of sustainable textiles applications.
ABSTRACT
Adipic acid was evaluated as a novel solvent for wet spinning of chitosan fibers. A solvent with two carboxyl groups could act as a physical crosslinker between the chitosan chains, resulting in improved properties of the fibers. The performance of adipic acid was compared with conventional solvents, i.e., lactic, citric, and acetic acids. Chitosan solutions were injected into a coagulation bath to form monofilaments. Sodium hydroxide (NaOH) and its mixture with ethanol (EtOH) were used as coagulation agents. Scanning electron microscopy confirmed the formation of uniform chitosan monofilaments with an even surface when using adipic acid as solvent. These monofilaments generally showed higher mechanical strength compared to that of monofilaments produced using conventional solvents. The highest Young's modulus, 4.45 GPa, was recorded for adipic acid monofilaments coagulated in NaOH-EtOH. This monofilament also had a high tensile strength of 147.9 MPa. Furthermore, taking advantage of chitosan insolubility in sulfuric acid (H2SO4) at room temperature, chitosan fibers were successfully formed upon coagulation in H2SO4-EtOH. The dewatering of fibers using EtOH before drying resulted in a larger fiber diameter and lower mechanical strength. Adipic acid fibers made without dehydration illustrated 18% (for NaOH), 46% (for NaOH-EtOH), and 91% (for H2SO4-EtOH) higher tensile strength compared to those made with dehydration.
ABSTRACT
OBJECTIVES: Emotion is a key component in language processing, but emotional words processing in children is still controversial. We aimed to investigate the relationship between emotional dimensions, arousal and valence, word familiarity, comprehension, use, and emotional content recognition. Eventually, a list of emotional content words for this age was prepared in Persian. MATERIALS&METHODS: The study was conducted in selected elementary schools in Tehran, Iran from April to June 2017. Emotional words, from adult emotional words list, were categorized into 5 groups according to their arousal and valence scores, including neutral, happy, calm, anxious and sad. Evaluation of familiarity, use, comprehension and emotional content recognition of the list was conducted with a checklist in 60 first grade children by speech and language pathologist. RESULTS: Neutral words gained the highest score in familiarity, use, comprehension and emotional content recognition (the mean=0.74). Afterward, there were the emotional words with high valence, calm (the mean=0.64) and happy (the mean=0.52). Finally, it was found the low score for valence emotional words, sad (the mean=0.46) anxious (the mean =0.43) in end of score rating. There was a significant difference between all word groups in four aspects (P-value<0.001). There were no significant differences between boys and girls in four aspects. CONCLUSION: Neutral words are better comprehended and expressed than emotional words. Valence is more effective than arousal in emotional words. Gender was not a determinant factor in all of the aspects. An emotional word list which is comprehensible for children in Persian language was prepared.
