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Smart Stimuli-Responsive Polylactic Acid-Hydrogel Fibers Produced via Electrospinning
Danaja Štular,Magnus Kruse,Vera Župunski,Laura Kreinest,Jožef Medved,Thomas Gries,Andreas Blaeser,Ivan Jerman,Barbara Simončič,Brigita Tomšič 한국섬유공학회 2019 Fibers and polymers Vol.20 No.9
In this research we propose a new type of smart microfibers, distinguished by moisture management and proactivetemperature and pH controlled release activity. Hydrogel with submicron-sized particles based on poly(Nisopropylacrylamide)(poly-NiPAAm) and chitosan (PNCS hydrogel) was incorporated into the structure of poly(lactic acid)(PLA) microfibers using the electrospinning technique. Composites with different PLA to PNCS hydrogel ratios wereprepared, and the chemical and morphological properties of the samples were studied using SEM, FT-IR and Ramanmapping. Additionally, the moisture management properties, which were provided by the temperature and pH-related phasechange transition of the incorporated PNCS hydrogel, were studied by determining the temperature-related static contactangle, thin-layer wicking, moisture content and pH-related water uptake. The loading and release abilities of the incorporatedPNCS hydrogel were studied using fluorescent microscopy. The increased concentration of the PNCS hydrogel in spinningsolutions resulted in greater variations in fiber thickness and deterioration of the mechanical properties of the fibers; thus, thehighest concentration of the PNCS hydrogel that could be incorporated within the fibers was found to be 20 % of the spinningmass. The composite sample showed temperature and pH responsiveness, a successful fluorescent-dye loading ability and itscontrolled release at predetermined conditions.
Alisa Šehić,Jelena Vasiljević,Igor Jordanov,Andrej Demšar,Jožef Medved,Ivan Jerman,Marija Čolović,Fiona Hewitt,T. Richard Hull,Barbara Simončič 한국섬유공학회 2018 Fibers and polymers Vol.19 No.6
This research investigated the influence of two flame retardant (FR) mixtures consisting melamine cyanurate (MeCy) and aluminum diethylphosphinate (AlPi), and MeCy and sodium aluminosilicate (SASi) at different weight ratios, on the flammability, thermal behavior and mechanical properties of polyamide 6 (PA6) composite yarns produced by meltspinning. The morphological and chemical properties of PA6/FR filaments were investigated by scanning electron microscopy and Fourier-transform infrared spectroscopy, flame retardancy by vertical burning test UL-94, thermal behavior by thermogravimetric and differential scanning calorimetric analyses, and mechanical properties by tensile tests. The results indicate that within the UL 94 V2 rating, the composite yarns differed significantly from each other in their burning and dripping behavior. The incorporation of both mixtures, MeCy+AlPi and MeCy+SASi, into the PA6/FR yarns significantly decreased the afterflame time relative to pristine PA6, confirming a lower production of flammable volatiles. This phenomenon was attributed mainly to MeCy, which caused an immediate extinguishment of the flame after the withdrawal of the igniting flame. Compared to one component MeCy, the incorporation of the MeCy+SASi mixture enhanced the thermooxidative stability of the PA6/FR yarns because of their additive effect at higher concentrations. In contrast, an antagonistic effect was obtained for the MeCy+AlPi mixture, irrespective of the concentration. Since the incorporation of MeCy+SASi did not drastically reduce the tensile properties of filaments, this mixture enables the production of the PA6/MeCy+SASi composite yarns with the enhanced flame retardancy and thermo-oxidative stability.
Vötterl Julia Christiane,Klinsoda Jutamat,Koger Simone,Hennig-Pauka Isabel,Verhovsek Doris,Metzler-Zebeli Barbara U. 아세아·태평양축산학회 2023 Animal Bioscience Vol.36 No.5
Objective: Dietary phytase increases bioavailability of phytate-bound phosphorus (P) in pig nutrition affecting dietary calcium (Ca) to P ratio, intestinal uptake, and systemic utilization of both minerals, which may contribute to improper bone mineralization. We used phytase to assess long-term effects of two dietary available P (aP) levels using a one-phase feeding system on gene expression related to Ca and P homeostasis along the intestinal tract and in the kidney, short-chain fatty acids in stomach, cecum, and colon, serum, and bone parameters in growing gilts and barrows. Methods: Growing pigs (37.9±6.2 kg) had either free access to a diet without (Con; 75 gilts and 69 barrows) or with phytase (650 phytase units; n = 72/diet) for 56 days. Samples of blood, duodenal, jejunal, ileal, cecal, and colonic mucosa and digesta, kidney, and metacarpal bones were collected from 24 pigs (6 gilts and 6 barrows per diet). Results: Phytase decreased daily feed intake and average daily gain, whereas aP intake increased with phytase versus Con diet (p<0.05). Gilts had higher colonic expression of TRPV5, CDH1, CLDN4, ZO1, and OCLN and renal expression of TRPV5 and SLC34A3 compared to barrows (p<0.05). Phytase increased duodenal expression of TRPV5, TRPV6, CALB1, PMCA1b, CDH1, CLDN4, ZO1, and OCLN compared to Con diet (p<0.05). Furthermore, phytase increased expression of SCL34A2 in cecum and of FGF23 and CLDN4 in colon compared to Con diet (p<0.05). Alongside, phytase decreased gastric propionate, cecal valerate, and colonic caproate versus Con diet (p<0.05). Phytase reduced cortical wall thickness and index of metacarpal bones (p<0.05). Conclusion: Gene expression results suggested an intestinal adaptation to increased dietary aP amount by increasing duodenal trans- and paracellular Ca absorption to balance the systemically available Ca and P levels, whereas no adaption of relevant gene expression in kidney occurred. Greater average daily gain in barrows related to higher feed intake.
Mutaz Al-Alawi,Loubna El Fels,Ramadan Benjreid,Tamas Szegi,Mohamed Hafidi,Barbara Simon,Miklos Gulyas 대한환경공학회 2020 Environmental Engineering Research Vol.25 No.3
Composting is among the most effective integrated waste management strategies used to recycle sewage sludge (SS) waste and generate a useful product. An encapsulated lifting system is a relatively new industrial-scale composting technology. The objective of this study was to evaluate the effectiveness of composting dewatered stabilized SS mixed with green waste using this new technology. The composting process was monitored by changes in the physico-chemical properties, UV-visible spectra, and fourier transform infrared (FTIR) spectra. The composting temperature was steady in the thermophilic range for 24 and 12 d in the intensive and maturation phases, respectively, which fulfilled the disinfection requirement. Moreover, the temperature increased rapidly to 76.8°C within three days, and the thermophilic temperatures peaked twice and lasted longer than in traditional composting, which accelerated SS degradation and decreased the composting period necessary to obtain mature compost. FTIR spectroscopic analysis showed a diminished in methyl group derived from methylene C-H aliphatic groups because of organic matter degradation by microorganisms and an increased number of aromatic chains. The new technology may be a viable and sustainable alternative for SS management that converts waste into compost that is useful as a soil amendment.
The Controlling Factors of Photochemical Ozone Production in Seoul, South Korea
Kim, Saewung,Jeong, Daun,Sanchez, Dianne,Wang, Mark,Seco, Roger,Blake, Donald,Meinardi, Simone,Barletta, Barbara,Hughes, Stacey,Jung, Jinsang,Kim, Deugsoo,Lee, Gangwoong,Lee, Meehye,Ahn, Joonyoung,Lee Taiwan Association for Aerosol Research 2018 Aerosol and air quality research Vol.18 No.9