A Practical Approach to Condition Assessment of Asphalt-Covered Concrete Bridge Decks on Korean Expressways by Dielectric Constant Measurements Using Air-Coupled GPR.

The main objectives of this study are to investigate the variations of the dielectric constant of concrete on Korean expressways by using a 1 GHz air-coupled Ground Penetrating Radar (GPR) system and to develop a practical approach to the condition assessment of concrete bridge decks with asphalt overlay on Korean expressways by dielectric constant measurements. A total of 684 GPR investigations of 601 actual concrete bridge decks, which are in service between 2 and 43 years, were carried out during the period between 1999 and 2013. Statistical analysis revealed that the dielectric constant of asphalt-covered concrete bridge decks reduced with service age and this trend continued until service age of over 40 years.

Effect of nanofiber content on bone regeneration of silk fibroin/poly(ε-caprolactone) nano/microfibrous composite scaffolds.

The broad application of electrospun nanofibrous scaffolds in tissue engineering is limited by their small pore size, which has a negative influence on cell migration. This disadvantage could be significantly improved through the combination of nano- and microfibrous structure. To accomplish this, different nano/microfibrous scaffolds were produced by hybrid electrospinning, combining solution electrospinning with melt electrospinning, while varying the content of the nanofiber.

Fabrication of microfibrous and nano-/microfibrous scaffolds: melt and hybrid electrospinning and surface modification of poly(L-lactic acid) with plasticizer.

Biodegradable poly(L-lactic acid) (PLA) fibrous scaffolds were prepared by electrospinning from a PLA melt containing poly(ethylene glycol) (PEG) as a plasticizer to obtain thinner fibers. The effects of PEG on the melt electrospinning of PLA were examined in terms of the melt viscosity and fiber diameter. Among the parameters, the content of PEG had a more significant effect on the average fiber diameter and its distribution than those of the spinning temperature.

Simple technique for spatially separated nanofibers/nanobeads by multinozzle electrospinning toward white-light emission.

Electrospun, emission color-tunable nanofibrous sheets were fabricated by multinozzle electrospinning equipped with a secondary electrode for the preparation of white-emissive sheets under a single excitation source, manipulating energy transfer between dyes. By control of the concentration of commercially available red, green, and blue dyes in the matrix polymer [poly(methyl methacrylate)], emission color tuning can be easily accomplished because each dye is located in spatially separated fibers to maintain enough distance to prevent or suppress energy transfer, allowing white-light emission. The application of dye separation for the white-light emission upon excitation with a blue light-emitting-diode lamp is demonstrated, indicative of its potential application for the easy and facile tuning of fluorescence color toward flexible illumination.

Fabrication of nanofibrous scaffold using a PLA and hagfish thread keratin composite; its effect on cell adherence, growth, and osteoblast differentiation.

Electrospinning is a useful method for the production of nanofibrous scaffolds in the field of tissue engineering. Keratin has been used as a biomaterial for electrospinning and can be used in a variety of biomedical applications because it is a natural protein, giving it the ability to improve cell affinity of scaffolds. In this study, keratin was extracted from hagfish slime thread (H-keratin) and blended with polylactic acid (PLA) polymer solution to construct a nanofibrous scaffold.

Stress response of fibroblasts adherent to the surface of plasma-treated poly(lactic-co-glycolic acid) nanofiber matrices.

Recent studies have shown that polymeric scaffolds as a synthetic extracellular matrix (ECM) are essential for regenerating tissues or organs in tissue engineering approaches. Controlling the surface functionality of polymer scaffolds is critical in regulation of cellular responses to the scaffolds during tissue formation. However, the stress response of cells to polymer scaffolds with different surface characteristics is not yet clear.

Effect of chitin/silk fibroin nanofibrous bicomponent structures on interaction with human epidermal keratinocytes.

To fabricate a biomimetic nanostructured bicomponent scaffolds, two types of chitin/silk fibroin (SF) nanofibrous scaffolds (blend scaffolds and hybrid scaffolds) were prepared by electrospinning or simultaneous electrospinning of chitin/SF solutions. The chitin/SF bicomponent scaffolds were after-treated with water vapor, and their nanofibrous structures were almost maintained. From the cytocompatibility and cell behavior on the chitin/SF blend or hybrid nanofibrous scaffolds, the hybrid matrix with 25% chitin and 75% SF as well as the chitin/SF blend nanofibers could be a potential candidate for tissue engineering scaffolds.

Biomimetic nanofibrous scaffolds: preparation and characterization of chitin/silk fibroin blend nanofibers.

Electrospinning of chitin/silk fibroin (SF) blend solutions in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) was investigated to fabricate a biomimetic nanostructured scaffolds for tissue engineering. The morphology of the electrospun chitin/SF blend nanofibers was investigated with a field emission scanning electron microscope (FE-SEM). The average diameters of chitin/SF blend fibers decreased from 920 to 340nm, with the increase of chitin content in blend compositions.

Biomimetic nanofibrous scaffolds: preparation and characterization of PGA/chitin blend nanofibers.

Electrospinning of poly(glycolic acid) (PGA)/chitin blend solutions in 1,1,1,3,3,3-hexafluoro-2-propanol was investigated to fabricate biodegradable and biomimetic nanostructured scaffolds for tissue engineering. The morphology of the electrospun PGA/chitin blend nanofibers was investigated with a field emission scanning electron microscope. The PGA/chitin blend fibers have average diameters of around 140 nm, and their diameters have a distribution in the range 50-350 nm.