UV photo-responsive characteristics of an n-channel GaN Schottky-barrier MISFET for UV image sensors

The ultraviolet (UV) responsive properties of the enhancement-mode n-channel Schottky-barrier MISFET (SB-MISFET), which was fabricated on a p-type GaN layer grown on silicon substrate, were investigated. The drain leakage current of the MISFET is less than 1 nA/mm/sup 2/, which is quite low compared to recently reported photodetectors. The MISFET exhibited a cutoff wavelength of 365 nm, and the UV/visible rejection ratio was about 120 near the threshold voltage. This is the first demonstration of the MISFET-type UV photodetector, which is highly applicable to the UV image sensors.     

A systematic approach to business process reengineering

In this study, a business process is defined as a set of various tasks which are closely inter-related and is assumed to have its own objectives to achieve. A set of processes constitute a business system. Many business process reengineering plans turned out to be unsuccessful because they are based on the existing process which assumed tasks along the process independent or based on the assumption that a process is independent of other processes. This approach generated redundant tasks or led to conflict between business processes. Under this approach, it very difficult to predict the result of the plan due to localized analysis of the process. To avoid aforementioned problems, a systematic, analytic and iterative approach to build up a master plan for business process reengineering is proposed.     

Effects of Cheonnyuncho (Opuntia humifusa) seeds treatment on the mass, quality, and the turnover of bone in ovariectomized rats

Cheonnyuncho (Opuntia humifusa), rich in polyphenols and flavonoids, is known to have medicinal benefits in the treatment of arteriosclerosis and inflammation. This study was undertaken to evaluate the effects of cheonnyuncho seed powder (OHS) on postmenopausal osteoporosis in ovariectomized rats. OHS treatment prevented an ovariectomy (OVX)-induced decrease in biomechanical quality of femurs. OHS also dose-dependently inhibited bone mineral density (BMD) decreases in femurs, which were accompanied by a significant decrease in skeletal remodeling, as evidenced by decreased levels of the bone turnover markers osteocalcin, alkaline phosphatase (ALP) activity, and serum and urinary Ca excretion. Micro-CT analysis of femoral metaphysics showed that OHS prevented the OVX-induced decrease in bone volume/tissue volume, trabecular thickness, and trabecular number. Concluded, the treatment with OHS improves bone biomechanical quality through modification of BMD and trabecular microarchitecture without hyperplastic effects on the uterus. For these reasons, OHS may be suitable as an alternative treatment of postmenopausal osteoporosis.     

Characterization of traditionally fermented Korean soybean paste, eoyukjang, and isolation of its microorganisms

In this study, traditionally fermented Korean soybean paste, eoyukjang, was characterized and its microorganisms were isolated. The contents of amino-type and ammonia-type nitrogens in the pastes we examined were 89.60 to 98.93 mg/% and 0.32 to 0.30 mM, respectively. Antioxidant activity increased during ripening, with antioxidant activities in 1- and 4-year-old pastes measured at 9.80 and 13.84 μmol of Trolox equivalents/g, respectively. Twenty-two and 19 microorganisms were isolated from soybean pastes under aerobic and anaerobic conditions, respectively. After identification, Bacillus amyloliquefaciens, Bacillus subtilis, and Bacillus vallismortis were dominant. In the enzyme activities, protease and lipoxygenase activities were observed from 0.065 to 0.733 unit/mg protein and 0.016 to 0.19 unit/mg protein, respectively. Amylase activity was, however, broad between 43.1 to 571.8 unit/mg protein.     

Effect of high hydrostatic pressure on immunomodulatory activity of cloudy apple juice

Present study investigated the effects of high hydrostatic pressure treatment (HHP, 500 MPa/3 min/ 25°C) on bioactive compound as well as antioxidant, immunomodulatory potentials, and microbial safety of cloudy juice from ‘Fuji’ apples. HHP did not cause any significant changes in vitamin C content whereas total polyphenol content was increased. The antioxidant potentials measured by DPPH and nitric oxide (NO) radical scavenging tests were preserved by HHP, while thermal treatment reduced antioxidant potentials. NO scavenging activity was greater than DPPH scavenging activity. The immunomodulatory effect assessed by splenocyte proliferation was increased in a dose-dependent manner, and HHP preserved immunomodulatory activity of apple juice. Furthermore, HHP treated juice was microbiologically safe without any physicochemical changes during 21 days of storage at 4°C. These results demonstrated the efficacy of HHP for preserving both nutritional and immunomodulatory functional characteristics of apple juice, and alternative method for preserving as freshly squeezed for up to 21 days.     

Inhibitory effect of phosphatidylserine on atopy-like dermatitis in NC/Nga mice

In the present study, the anti-atopic effect of phosphatidylserine (PS) extracted from soybean was investigated in NC/Nga mice. The atopic symptoms were evaluated by scoring spontaneous scratching behavior and skin lesions, by measuring serum levels of immunoglobulin E (IgE) and interleukin-4 (IL-4), and by observing skin histology. After observing the maximum severity of atopic symptoms, PS was initiated. The PS treatment significantly alleviated apparent symptoms of atopic dermatitis and scratching behavior. The suppression of atopic dermatitis by PS was verified by decreases in the serum levels of IgE (p<0.05 after 8 weeks; p<0.001 after 9 weeks) and IL-4 (p<0.01 after 7 weeks; p<0.001 after 9 weeks). Histological observations also indicated that the thickening process of skin and the infiltration of inflammatory cells were significantly inhibited. Taken together, PS from soybean might be useful for alleviating atopic dermatitis symptoms and thus for developing a new medicine for treating human atopic disease.     

Standardization of ginseng processing for maximizing the phytonutrients of ginseng

This study was designed to optimize the process conditions, such as steaming, drying, and extracting, for obtaining the maximum content of prosapogenin (Rg3, Rg2, Rh1, and Rh2) from red ginseng, which has antitumor and anti-cancer properties. The steaming process was performed in an autoclave and the drying and extracting processes were done in dryer and heat extractor, respectively, and content of each prosapogenin was analyzed by HPLC. In the steaming process, prosapogenin values did not show any significant increase at 80 or 90°C, but tended to increase sharply as the steaming period became longer at 100°C, and the maximum value was obtained at 100°C with 6 h of steaming without any significant difference between local Gyeonggi areas. Drying red ginseng at 70°C for 24 h was the optimal condition to enhance prosapogenin extraction without affecting the quality. Maximal crude saponin and prosapogenin contents were obtained using 70% ethanol as the solvent at 70°C in the extracting process. Using these standardization processes such as steaming, drying, and extraction, maximum prosapogenin values could be obtained at ginseng factories.

     

Synthesis of Gold-Platinum Core-Shell Nanoparticles Assembled on a Silica Template and Their Peroxidase Nanozyme Properties

Bimetallic nanoparticles are important materials for synthesizing multifunctional nanozymes. A technique for preparing gold-platinum nanoparticles (NPs) on a silica core template (SiO₂@Au@Pt) using seed-mediated growth is reported in this study. The SiO₂@Au@Pt exhibits peroxidase-like nanozyme activity has several advantages over gold assembled silica core templates (SiO₂@Au@Au), such as stability and catalytic performance. The maximum reaction velocity (V_max) and the Michaelis–Menten constants (K_m) were and 2.1 × 10⁻¹⁰ M⁻¹∙s⁻¹ and 417 µM, respectively. Factors affecting the peroxidase activity, including the quantity of NPs, solution pH, reaction time, and concentration of tetramethyl benzidine, are also investigated in this study. The optimization of SiO₂@Au@Pt NPs for H₂O₂ detection obtained in 0.5 mM TMB; using 5 µg SiO₂@Au@Pt, at pH 4.0 for 15 min incubation. H₂O₂ can be detected in the dynamic liner range of 1.0 to 100 mM with the detection limit of 1.0 mM. This study presents a novel method for controlling the properties of bimetallic NPs assembled on a silica template and increases the understanding of the activity and potential applications of highly efficient multifunctional NP-based nanozymes.     

Preparation and characterization of weather resistant silicone/acrylic resin coatings

Preparation and characterization of weather resistant silicone/acrylic resin coatings were conducted. In order to prepare these coatings, a silicone/acrylic resin (KLD) was first prepared by an addition polymerization reaction of monomers, including n-butyl acrylate, methyl methacrylate, n-butyl methacrylate, and 3-methacryloxypropyltrimethoxysilane (MPTS). In the preparation of the silicone/acrylic resin, T_g of the acrylic copolymer was fixed at 40°C and the contents of MPTS were varied to be 10, 20, and 30 wt%. The weather resistant silicone/acrylic resin coatings were then prepared by blending the synthesized silicone/acrylic resin and TiO₂. The viscosity of the synthesized resin decreased with the content of MPTS, whereas the thermal stability at high temperature increased. The prepared coatings exhibited excellent adhesion to various substrates, and various physical properties of the coatings were satisfactory. The weatherability of the coatings was tested three ways: outdoor exposure test, Weather-Ometer (WOM), and QUV accelerated weatherability tester (QUV). The gloss retention, yellowness index difference, color difference, and lightness index difference were improved at high MPTS concentration. The coatings containing 30 wt% MPTS have especially good weather properties. Dept. of Chem. Eng., Yongin 449-728, Korea. Ansan 425-110, Korea.