• Journal of Microbiology and Biotechnology
• /
• v.9 no.6
• /
• pp.695-703
• /
• 1999

We have studied the stereospecificities of various pyridoxal 5'-phosphate (PLP) dependent enzymes for the hydrogen transfer between the C-4' of a bound coenzyme and the C-2 of a substrate in the transamination catalyzed by the enzymes. Stereospecificities reflect the structures of enzyme active-sites, in particular the geometrical relationship between the coenzyme-substrate Schiff base and the active site base participating in an $\alpha$-hydrogen abstraction. The PLP enzymes studied so far catalyze only a si-face specific (pro-S) hydrogen transfer. This stereochemical finding suggests that the PLP enzymes have the same topological active-site structures, and that the PLP enzymes have evolved divergently from a common ancestral protein. However, we found that o-amino acid aminotransferase, branched chain L-amino acid aminotransferase, and 4-amino-4-deoxychorismate lyase, which have significant sequence homology with one another, catalyze a re-face specific (pro-R) hydrogen transfer. We also showed that PLP-dependent amino acid racemases, which have no sequence homology with any aminotransferases, catalyze a non-stereospecific hydrogen transfer: the hydrogen transfer occurs on both faces of the planar intermediate. Crystallographical studies have shown that the catalytic base is situated on the re-face of the C-4' of the bound coenzyme in o-amino acid aminotransferase and branched chain L-amino acid aminotransferase, whereas the catalytic base is situated on the si-face in other aminotransferases (such as L-aspartate aminotransferase) catalyzing the si-face hydrogen transfer. Thus, we have clarified the stereospecificities of PLP enzymes in relation with the primary structures and three-dimensional structures of the enzymes. The characteristic stereospecificities of these enzymes for the hydrogen transfer suggest the convergent evolution of PLP enzymes.

• Korean Journal of Human Ecology
• /
• v.23 no.4
• /
• pp.733-742
• /
• 2014

Atopic dermatitis is a chronic relapsing inflammatory skin disease. In the past years, numbers of children with atopic dermatitis has increased all over the world. Objective of this study was to evaluate awareness of students in atopy-friendly elementary schools about environmentally-friendly grown agricultural products and their practice levels for dietary guidelines. This study was conducted by using a questionnaire on 116 students from three atopy-friendly schools in Jin-an, Jeong-eup, and Gwang-ju and 124 students from general elementary schools. According to the results, the numbers of children who suffer from atopic dermatitis between atopy-friendly schools and general schools were not significantly different. Among, students with atopic dermatitis, more students in atopy-friendly school, compared to general school, restricted foods. Since different school feeding services have been provided, students in atopy-friendly schools generally get more information about the environmentally-friendly agricultural products through nutrition education. However, most results did not show differences in knowledge levels and practice levels for dietary guidelines for children between students in atopy-friendly schools and general schools about environmentally-friendly produces. However, students in atopy-friendly schools less frequently eat cookies, soda drinks, or fast foods. In conclusion, appropriate program for nutrition education should be provided to elementary school students with atopic dermatitis.

• Journal of Nutrition and Health
• /
• v.34 no.3
• /
• pp.338-347
• /
• 2001

Cigarette smoking has a negative effect for nutrient intakes and nutritional status of antioxidant nutrients including vitamin C. This study has been performed to compare the dietary nutrient intakes, serum vitamin C concentration and serum cotinine concentration of smoking teenage girls(n=104) with those of non-smoking teenage girls(n=791). The subjects were 895 high school girls(15-19 years of age) living in a rural community in Korea. Of the subjects, 11.6% stated that they were currently smoking. The frequency of taking alcohol, soda and coffee was higher in smokers than in non-smokers, respectively. The usage rate of vitamin/mineral supplements was higher in smokers than in non-smokers. The smokers tended to skip breakfast and lunch and to take snack more often than did the non-smokers. The dietary intakes of calorie, protein, vitamin A, vitamin B, vitamin C, calcium and iron were lower in smokers than in non-smokers. Daily mean intakes of these nutrients were less than the 2/3 of the Korean RDAs in smokers while these intakes were similar to or more than the RDAs in non-smokers. The ratio of under weight or lean tended to be higher in smokers. Serum vitamin C concentration was lower in smokers than in non-smokers. These findings show that smokers have unsound eating habits and poor nutirtional status. In particular, nutritional status of vitamin C is significantly poor in smokers, and this tendency can be found more notably in heavy smokers. Therefore, oxidative stress may be present in young teenage girls with short smoking history as evidence by above results. (Korean J Nutrition 34(3) : 338∼347, 2001)

• Nutrition Research and Practice
• /
• v.8 no.1
• /
• pp.74-80
• /
• 2014

Water is essential for life and plain water instead of sugar-sweetened beverages is one approach for decreasing energy intake. Due to limited data on characteristics associated with water intake among Korean adolescents, this study examined associations of demographic and behavioral characteristics with plain water intake by using nationally representative sample of South Korean adolescents. The data (2007-2010 Korea National Health and Nutrition Examination Survey) for 1,288 high school-aged adolescents (15-18 years) were used. Multivariable logistic regression was used to calculate adjusted odds ratios (OR) for factors associated with low water intake (< 4 cups/day) and very low water intake (< 2.5 cups/day). Nationwide, 38.4% and 19.0% of adolescents reported drinking water < 4.0 cups/day and < 2.5 cups/day, respectively. The mean plain water intake was 5.7 cups/day for males and 4.1 cups/day for females. Females had significantly higher odds for drinking water < 2.5 cups/day (OR = 2.2) than males, whereas adolescents with low milk consumption had significantly lower odds for drinking water < 2.5 cups/day (OR = 0.7). Factors significantly associated with a greater odds for drinking water < 4 cups/daywere being female (OR = 2.8) and not meeting physical activity recommendations (${\geq}20$ min/day on < 3 days/week) (OR = 1.6). Being underweight, overweight, and obese were significantly associated with reduced odds for drinking water < 4 cups/day (OR = 0.7, 0.4 and 0.5, respectively). However, intake of soda, coffee drinks, fruits, vegetables, and sodium and eating out were not significantly associated with low or very low water intake. These findings may be used to target intervention efforts to increase plain water intake as part of a healty lifestyle.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.398.1-398.1
• /
• 2014

The $Cu_2ZnSnSe_4$ (CZTSe) thin films solar cell is one of the next generation candidates for photovoltaic materials as the absorber of thin film solar cells because it has optimal bandgap (Eg=1.0eV) and high absorption coefficient of $10^4cm^{-1}$ in the visible length region. More importantly, CZTSe consists of abundant and non-toxic elements, so researches on CZTSe thin film solar cells have been increasing significantly in recent years. CZTSe thin film has very similar structure and properties with the CIGS thin film by substituting In with Zn and Ga with Sn. In this study, As-deposited CZTSe thin films have been deposited onto soda lime glass (SLG) substrates at different deposition condition using Pulsed Laser Deposition (PLD) technique without post-annealing process. The effects of deposition conditions (deposition time, deposition temperature) onto the structural, compositional and optical properties of CZTSe thin films have been investigated, without experiencing selenization process. The XRD pattern shows that quaternary CZTSe films with a stannite single phase. The existence of (112), (204), (312), (008), (316) peaks indicates all films grew and crystallized as a stannite-type structure, which is in a good agreement with the diffraction pattern of CZTSe single crystal. All the films were observed to be polycrystalline in nature with a high (112) predominant orientation at $2{\theta}{\sim}26.8^{\circ}$. The carrier concentration, mobility, resistivity and optical band gap of CZTSe thin films depending on the deposition conditions. Average energy band gap of the CZTSe thin films is about 1.3 eV.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2010.05a
• /
• pp.36.1-36.1
• /
• 2010

While the substrate-type solar cells with Cu(In,Ga)Se2 absorbers yield conversion efficiencies of up 20%[1], the highest published efficiency of Cu(In,Ga)Se2 superstrate solar cell is only 12.8% [2]. The commerciallized Cu(In,Ga)Se2 solar cells are made in the substrate configuration having the stacking sequence of substrate (soda lime glass)/back contact (molybdenum)/absorber layer (Cu(In,Ga)Se2)/buffer layer (cadmium sulfide)/window layer (transparent conductive oxide)/anti reflection layer (MgF2) /grid contact. Thus, it is not possible to illuminate the substrate-type cell through the glass substrate. Rather, it is necessary to illuminate from the opposite side which requires an elaborate transparent encapsulation. In contrast to that, the configuration of superstrate solar cell allows the illumination through the glass substrate. This saves the expensive transparent encapsulation. Usually, the high quality Cu(In,Ga)Se2 absorber requires a high deposition temperature over 550C. Therefore, the front contact should be thermally stable in the temperature range to realize a successful superstrate-type solar cell. In this study, it was tried to make a decent superstrate-type solar cell with the thermally stable ZnO:Al layer obtained by adjusting its deposition parameters in magnetron sputtering process. The effect of deposition condition of the layer on the cell performance will be discussed together with hall measurement results and current-voltage characteristics of the cells.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.05c
• /
• pp.108-111
• /
• 2002

CIGS film has been fabricated on soda-lime glass, which is coated with Mo film. by multi-source evaporation process. The films has been prepared with thickness of 1.0 ${\mu}m$, 1.75${\mu}m$, 2.0${\mu}m$, 2.3${\mu}m$, and 3.0${\mu}m$. X-ray diffraction analysis with film thickness shows that CIGS films exhibit a strong (112) preferred orientation. Furthermore. CIGS films exhibited distinctly decreasing the full width of half-maximum and (112) preferred peak with film thickness. Also, The film's microstructure, such as the preferred orientation, the full width at half-maximum(FWHM), and the interplanar spacing were examined by X-ray diffraction. The preparation condition and the characteristics of the unit layers were as followings ; Mo back contact DC sputter, CIGS absorber layer : three-stage coevaporation, CdS buffer layer : chemical bath deposition, ZnO window layer : RF sputtering, $MgF_2$ antireflectance : E-gun evaporation

• Journal of the Korean institute of surface engineering
• /
• v.51 no.2
• /
• pp.126-132
• /
• 2018

SnS thin films with different substrate temperatures ($150 {\sim}300^{\circ}C$) as process parameters were grown on soda-lime glass substrates by RF magnetron sputtering. The effects of substrate temperature on the structural and optical properties of SnS thin films were investigated by X-ray diffraction (XRD), Raman spectroscopy (Raman), field-emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), and Ultraviolet-visible-near infrared spectrophotometer (UV-Vis-NIR). All of the SnS thin films prepared at various substrate temperatures were polycrystalline orthorhombic structures with (111) planes preferentially oriented. The diffraction intensity of the (111) plane and the crystallite size were improved with increasing substrate temperature. The three major peaks (189, 222, $289cm^{-1}$) identified in Raman were exactly the same as the Raman spectra of monocrystalline SnS. From the XRD and Raman results, it was confirmed that all of the SnS thin films were formed into a single SnS phase without impurity phases such as $SnS_2$ and $Sn_2S_3$. In the optical transmittance spectrum, the critical wavelength of the absorption edge shifted to the long wavelength region as the substrate temperature increased. The optical bandgap was 1.67 eV at the substrate temperature of $150^{\circ}C$, 1.57 eV at $200^{\circ}C$, 1.50 eV at $250^{\circ}C$, and 1.44 eV at $300^{\circ}C$.

• Korean Journal of Community Nutrition
• /
• v.11 no.3
• /
• pp.338-345
• /
• 2006

The purpose of this study was to design an interactive multimedia nutrition education program for preschoolers. Computer technology provides the opportunity to explore new and creative methods of delivering nutrition education to pre-schoolers. If this method is effective, more preschoolers can be reached with accurate and consistent nutrition education with less time and teaching staff. This program is a computer-based multimedia nutrition education program for pre-schoolers based on the Dick and Carey (Dick & Carey 2001) model of instructional design which includes analysis, design, development, and evaluation. The overall instructional goal was based on the needs of the target population. The needs assessment was a self-administered survey distributed to 1,426 parents of preschoolers, focusing on the need for preschoolers' nutrition education. The results of the survey indicated that parents wanted their children to learn reasons for eating nutritious food. Therefore, a program titled 'Nutrition Exploration' was developed with the instructional goal of teaching preschoolers the 5 Food Groups. To achieve this goal, the preschoolers were engaged in a game. They could earn colored jewels by completing the game in five sessions. The story line was that people living in a peaceful kingdom become sick after they lose the jewels. The learner takes an adventurous journey through five different countries to retrieve the jewels. These countries are 'Giwoon nahrah' (foods containing carbohydrates, such as rice and potatoes), 'Sangsang nahrah' (foods that are rich in vitamins and minerals, such as vegetables and fruits), 'Sooksook nahrah' (calcium-con-taming products such as milk), 'Teunteun nahrah' (protein-containing foods such as meat and fish) , and 'Gakeum nahrah' (products with high sugar and fat content, such as instant foods and soda). The learner who obtains five jewels in five different countries can save the kingdom. For the program to be effective and efficient, the multimedia had to be easy for the preschooler to enter, use, and exit. The verbal instructions enhanced child autonomy, and the program was developmentally appropriate so that the young child could easily manipulate the software. This research provides the basis for the continued development of computer-based nutrition education materials.

• Journal of environmental and Sanitary engineering
• /
• v.13 no.1
• /
• pp.16-25
• /
• 1998

Laboratory-scale experiment using anaerobic fluidized bed reactor was carried out to investigate the prehydrolysis step with caustic soda on the treatment efficiency of anaerobic sludge treatment, since the overall rate-limiting step for the complete anaerobic digestion of sludge was the hydrolysis step by extracellular bacterial enzymes of insoluble polymeric molecules. Reactors received a sludge which had not been pretreated, a 50-50 mixture of pretreated and untreated sludge, and the fully pretreated sludge. Hydraulic retention time of 10, 5, 2.5 days and 1 day were applied with an respective equivalent organic loading rate of 1.17, 2.23, 4.17, 11.24 gCOD/L/d. Reactor with the untreated sludge did not archieve adequate digestion even at the HRT of 5 days, and reactor, which received the 50-50 mixture, operated well at the HRT of 5 days, but began to show signs of unstable digestion at the HRT of 2.5 days. While, reactor, which was fed the hydrolyzed sludge, operated reasonably well at the 2.5 days, but was showing somewhat decrease in removal efficiencies. Results, therefore, have substantiated that the limiting reaction in the anaerobic treatment process is hydrolysis. The soluble COD did not significantly accumulate in the reactor as organic acid form, even when they were highly stressed. It was believed that this resistance to a build-up of organic acids and soluble COD behavior was mainly due to the maintenance of the methane bacteria in the fixed-film system which prevents washout as the organic loading increased. The anaerobic fluidized bed reactor was therefore effective for the digestion of waste activated sludge at short HRT.