Chonbuk National University

About: Chonbuk National University is a education organization based out in Jeonju, South Korea. It is known for research contribution in the topics: Apoptosis & Nanofiber. The organization has 14820 authors who have published 28884 publications receiving 554131 citations.

Electrospun poly(vinyl alcohol) nanofibers: effects of degree of hydrolysis and enhanced water stability

Abstract: The effects of the degree of hydrolysis (DH) of poly(vinyl alcohol) (PVA) on electrospinning and water resistance of electrospun PVA/poly(acrylic acid) (PAA) composite fibers were explored. At a constant concentration of PVA solution (∼8wt%), the average diameter of electrospun PVA fibers increased with increasing DH. The water resistance of heat-treated PVA/ PAA composite fibers was dramatically enhanced, and was also affected by PAA weight fractions (φPAA) in PVA/PAA blend solutions.

Anthraquinones isolated from Cassia tora (Leguminosae) seed show an antifungal property against phytopathogenic fungi.

Abstract: The fungicidal activities of Cassia tora extracts and their active principles were determined against Botrytis cineria, Erysiphe graminis, Phytophthora infestans, Puccinia recondita, Pyricularia grisea, and Rhizoctonia solani using a whole plant method in vivo and were compared with synthetic fungicides and three commercially available anthraquinones. The responses varied with the plant pathogen tested. At 1 g/L, the chloroform fraction of C. tora showed a strong fungicidal activity against B. cinerea, E. graminis, P. infestans, and R. solani. Emodin, physcion, and rhein were isolated from the chloroform fraction using chromatographic techniques and showed strong and moderate fungicidal activities against B. cinerea, E. graminis, P. infestans, and R. solani. Furthermore, aloe-emodin showed strong and moderate fungicidal activities against B. cinerea and R. solani, respectively, but did not inhibit the growth of E. graminis, P. infestans, P. recondita, and Py. grisea. Little or no activity was observed for anthraquinone and anthraquinone-2-carboxylic acid when tested at 1 g/L. Chlorothalonil and dichlofluanid as synthetic fungicides were active against P. infestans and B. cinerea at 0.05 g/L, respectively. Our results demonstrate the fungicidal actions of emodin, physcion, and rhein from C. tora.

Investigation of a Single Pd Nanowire for Use as a Hydrogen Sensor

Abstract: Interest in nanowire technology has grown significantly over the past several years, due to their potentially broad applications in optics, electronics, and sensors (e.g., resonators, molecular detection, nanoconnectors, biosensors, and gas sensors). Due to their small size, sensitivity, real-time detection, and ultra-low power demands, nanowire sensors are being investigated for detection of a wide range of chemical and biochemical species. The techniques used to fabricate these sensors include laser ablation cluster formation, focused ion-beam etching of electrodes to create a small gap ( 100 nm), use of ion-track membranes, use of alumina templates, and electrochemical step-edge decoration. These techniques have drawbacks of limited controllability and manufacturability, therefore reliable and controllable nanowire fabrication remains a significant challenge. We have previously reported a method of electrodepositing Pd wires with micrometer diameters and conducting polymer nanowires of polyaniline and polypyrrole with diameters of 100 nm. In this work, single Pd nanowires are fabricated by electrodeposition in electrolyte channels patterned with electron-beam lithography, and hydrogen sensing is demonstrated. This fabrication technique can produce nanowires with controlled dimensions, positions, alignments, and chemical compositions, and potentially enables the use of a wide range of materials for creating arrays of singlenanowire sensors. Additionally, the growth of nanowires using this technique would allow for easy integration with existing silicon technology. Figure 1 shows SEM images of typical electrodeposited nanowires between electrodes. The magnified image in Figure 1b shows a single Pd nanowire with a diameter ranging from 70 to 85 nm. An EDS (energy dispersive spectroscopy) elemental analysis detected only Pd metal in the nanowire.

Property enhancement of a carbon fiber/epoxy composite by using carbon nanotubes

Abstract: We investigated the effect of carbon nanotube (CNT) modifications on the flexural and wear behaviors of multiscale carbon/CNT/epoxy composites in this study. Carbon/epoxy woven composites and two types of multiscale carbon/CNT/epoxy composites were fabricated by incorporating woven-type carbon fibers into epoxy matrices modified with 2 wt% acid-treated and silane-treated multi-walled carbon nanotubes (MWCNTs). Three-point bending and ball-on-disk wear tests were performed on the three composites. The results showed that the flexural moduli and strengths of carbon/CNT/epoxy composites were greater than those of carbon/epoxy composites, regardless of CNT modification. Specifically, the flexural modulus and strength of the silane-treated specimens were 10% and 15% greater, respectively, than those of the acid-treated samples. The results also showed that the wear properties of carbon/epoxy composites are improved by the addition of CNTs. In addition, the wear properties of silane-treated samples were superior to those of acid-treated samples. Scanning electron microscopic examination of fractured and worn surfaces showed that the improvement in the flexural and wear properties of the silane-treated carbon/CNT/epoxy composites was attributed to the improved dispersion of CNTs in the epoxy and the better interfacial characteristics caused by the silanization of the CNTs.