Encapsulation of Phytoncide in Nanofibers by Emulsion Electrospinning and their Antimicrobial Assessment

Phytoncides are volatile organic compounds released from trees and plants and are well known for their natural antibacterial activity. In this study, emulsion electrospinning was used to encapsulate phytoncide in the core of nanofibers, with the aim of developing environmentally friendly, functional nanofibers with a sustained release of the encapsulated component. Core/sheath structured phytoncide/poly(vinyl alcohol) nanofibers were successfully prepared by emulsion electrospinning using an ordinary single-nozzle electrospinning setup. An oil-in-water emulsion of an aqueous solution of poly(vinyl alcohol) (as the aqueous phase) and phytoncide (as the oil phase) was used to prepare the core/sheath structured nanofibers. Nanocomposite fibers were electrospun under various spinning conditions and emulsion formulations to find the suitable processing conditions for fabricating nanofibers with core/sheath structures. The resulting nanofibers exhibited a well-aligned core/sheath structure with fiber diameters of 250-350 nm. The release profile of phytoncide from the core of nanofibers over a 21 day period showed that phytoncide was released in a sustained manner over 14 days. The core/sheath structured phytoncide/poly(vinyl alcohol) nanofibers exhibited 99.9 % bacterial reduction against both Staphylococcus aureus and Escherichia coli, indicating that the encapsulated phytoncide in the fiber provided strong antimicrobial effects.     

A review on microbial and toxic risk analysis procedure for reclaimed wastewater irrigation on paddy rice field proposed for South Korea

Water shortage has become a major agricultural concern, and “The Sustainable Water Resources Research Program” in Korea is currently addressing this problem through the development of treatment systems for reclaiming wastewater and the assessment of human health risks associated with its reuse. Through this program, started in 2001, many studies have examined various water resources. Reclaiming wastewater is one way to alleviate water-shortage pressures, and one of the major potential uses of reclaimed water is irrigation. However, the main concern with reusing reclaimed wastewater is the increased likelihood of human contact that might result in exposure to pathogens and increased health risks. Relatively few studies have examined the toxic risks using reclaimed wastewater for irrigation in rice paddy fields. This study provides an overview of methods for quantitative microbial risk assessment and toxic risk assessment of heavy metal concentrations developed in the previous studies that can be applied to the evaluation of rice paddy fields irrigated with reclaimed wastewater in South Korea.     

Colorimetric detection of transition metal ions with azopyridine-based probing molecule in aqueous solution and in PMMA film

We report on an azopyridine derivative for probing transition metal ions and fabrication of its films. The probe, AP, showed a sensitive absorption change toward transition metal ions, especially cobalt ion, even at the concentration of ppm range, accompanied by yellow-to-red color transition with noticeable isosbestic point. In addition, the AP-containing PMMA film with high transparency can be fabricated by spin-casting without any aggregation of AP. The film with PMMA matrix shows good sensitivity toward cobalt ion similar to the case in the solution with a feature of metallochromic transition.     

Chemical Composition,Antifeedant, Repellent,and Toxicity Activities of the Rhizomes of Galangal,Alpinia galanga Against Asian Subterranean Termites,Coptotermes gestroi and Coptotermes curvignathus (Isoptera: Rhinotermitidae)

Dual choice bioassays were used to evaluate the antifeedant property of essential oil and methanolic extract of Alpinia galanga (L.) (locally known as lengkuas) against two species of termites, Coptotermes gestroi (Wasmann) and Coptotermes curvignathus (Holmgren) (Isoptera: Rhinotermitidae). A 4-cm-diameter paper disc treated with A. galanga essential oil and another treated with either methanol or hexane as control were placed in a petri dish with 10 termites. Mean consumption of paper discs (miligram) treated with 2,000 ppm of essential oil by C. gestroi was 3.30 ± 0.24 mg and by C. curvignathus was 3.32 ± 0.24 mg. A. galanga essential oil showed significant difference in antifeedant effect, 2,000 ppm of A. galanga essential oil was considered to be the optimum concentration that gave maximum antifeedant effect. The essential oil composition was determined using gas chromatography-mass spectrometry. The major component of the essential oil was 1,8-cineol (61.9%). Antifeedant bioassay using 500 ppm of 1,8-cineol showed significant reduction in paper consumption by both termite species. Thus, the bioactive agent in A. galangal essential oil causing antifeeding activity was identified as 1,8-cineol. Repellent activity shows that 250 ppm of 1,8-cineol caused 50.00 ± 4.47% repellency for C. gestroi, whereas for C. curvignathus 750 ppm of 1,8-cineol was needed to cause similar repellent activity (56.67 ± 3.33%). C. curvignathus is more susceptible compare to C. gestroi in Contact Toxicity study, the lethal dose (LD₅₀) of C. curvignathus was 945 mg/kg, whereas LD₅₀ value for C. gestroi was 1,102 mg/kg. Hence 1,8-cineol may be developed as an alternative control against termite in sustainable agriculture practices.     

Silage and total mixed ration hygienic quality on commercial farms: implications for animal production

Implications of silage hygienic quality for animal production were investigated on forty‐five dairy farms in South West England. Samples of grass and maize silages and of total mixed rations (TMR) were obtained together with information on silage technology, herd size and animal production. Samples were analysed for mycotoxins, bacteria, yeasts, moulds and chemical composition. Thirteen mycotoxins were assayed, but none were detected in the samples of grass silage. However, mycotoxins were found in 0·9 of all maize and other silage samples, with deoxynivalenol and zearalenone predominating. There was no relationship between total mycotoxin concentration and mean lactation milk yield per cow. Enterobacteria counts tended to be higher in maize silage than in grass silage and higher still in TMR – a cause for concern. There were no relationships between mould counts and mycotoxin concentrations in silages, implying that mycotoxins may have been produced in the field pre‐ensiling.     

Directly-prelithiated carbon nanotube film for high-performance flexible lithium-ion battery electrodes

Carbon nanotube (CNT) films are very flexible and serve as active materials for lithium-ion batteries (LIBs). Hence, they have high potential as flexible free-standing electrodes for wearable batteries. However, nanocarbon materials such as CNTs and graphene are of limited use as electrodes because they have a large initial irreversible capacity due to the formation of a solid electrolyte interphase (SEI). Herein, we prelithiated the CNT films to make them available as electrodes for flexible batteries by reducing their irreversible capacity. The SEI is pre-formed through a direct prelithiation (DP) method that brings lithium metal into direct contact with CNT films in an electrolyte. As a result, the capacity of directly-prelithiated CNT film electrodes continues to increase to 1520 mAh/g until 350th cycle of charge/discharge and their initial irreversible capacity vanishes. The changes in the electrochemical properties of CNT film electrodes by DP treatment and their flexibility are investigated.     

Fabrication of electropsun PLGA and small intestine submucosa-blended nanofibrous membranes and their biocompatibility for wound healing

In recent decades, tremendous research has focused on the production of nanoscale fibers using synthetic polymers, with the goal of fabricating nanofibrous scaffolds for wound healing. However, the hydrophobicity of such polymers typically hinders attachment and proliferation of the cells. In this study, we combined poly-d,l-lactide-co-glycolide (PLGA) and small intestine submucosa (SIS) to fabricate blended nanofibers for wound healing by electrospinning. PLGA and SIS were dissolved in 1,1,1,3,3,3-hexafluoro isopropanol to produce different weight ratios of PLGA/SIS-blended nanofibrous membranes (NFM). Physicochemical characterization of the electrospun NFM was performed by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, water contact angle analysis, degradation test and tensile testing. The PLGA/SIS-blended NFM showed improved hydrophilicity and tensile strength. Better infiltration, attachment and proliferation of rat granulation fibroblasts of PLGA/SIS-blended NFMs compared to PLGA NFMs were identified by morphological differences determined by SEM and a water-soluble tetrazolium salt assay kit. Based on our results, the PLGA/SIS blended NFMs were found to be suitable for use as a potential material for wound dressing.     

Electrical properties of graphene/waterborne polyurethane composite films

Graphene is classified as a carbon-based material. Structurally, graphene is made up of carbon-based two-dimensional atomic crystals and a one atom thick planar sheet of sp²-bonded carbon atoms. This sort of arrangement in graphene makes it a unique material with exceptional mechanical, physicochemical, thermal, electrical, optical, and biomedical properties. Methods for graphene-based fabric production mainly use graphene-based materials such as graphene (G), graphene oxide (GO), and reduced graphene oxide (rGO) coated on fabric or yarn. Waterborne polyurethane (WPU) is one of the most rapidly developing and active branches of polyurethane chemistry. More and more attention is being paid to graphene-coated fabrics owing to their low temperature flexibility, the presence of zero or very few VOCs (volatile organic compounds), water resistance, pH stability, superior solvent resistance, excellent weathering resistance, and desirable chemical and mechanical properties. It is used as a coating agent or adhesive for fibers, textiles, and leather. Also, graphene-containing materials have been used to enhance the properties of WPU. In this study, graphene/WPU composite solution and film was prepared to conduct basic research for developing electrical heating textiles which is not harmful to the human body, flexible and excellent in electrical properties. Graphene/WPU composite solutions were prepared with a graphene content of 0, 2, 4, 8, and 16 wt%, and graphene/WPU film was prepared with solution casting method. The graphene contents were analyzed for their surface morphology, electrical properties, and electrical heating properties.