목적 : 본 연구는 8세에서 19세의 근시 학생을 대상으로 어린이 근시관리 누진 안경렌즈의 착용실태를 조사하고 착용 후 2년간 근시도의 변화를 확인하고자 하였다. 방법 : 2019년 6월부터 2023년 5월까지 수원 G 안경원에서 어린이 근시관리 누진렌즈를 구매한 110명을 대상 으로 근시 진행완화를 위해 렌즈의 착용을 지속하고 있는지 그리고 중도 포기했다면 그 이유를 조사하였다. 그 후 2차 정기방문으로 안경을 다시 교정받은 기록이 있는 72명을 대상으로 초점렌즈(A그룹, 33명)와 어린이 근시관리 누진렌즈(B그룹, 39명)를 착용한 두 그룹으로 나누어 2년간 추적 조사하였다. 결과 : 어린이 근시관리 누진렌즈를 처방받은 110명의 1차 대상자 중 15명(13.6%)이 근시진행 완화 안경 착용 을 중도 포기했으며 이들 중 남자는 11명(73.3%), 여자는 4명(26.6%) 이었다. 또한, 중도 포기한 이유로는 구매의 편의성과 비용문제가 주된 이유로 조사되었다. 1차, 2차, 3차 방문 시기에 평균 등가구면 굴절력은 A그룹에서는 – 2.09±1.43, –2.78±1.52, –3.31±1.55 D이었고, B그룹은 –2.04±1.08, –2.63±1.06, -2.94±1.08 D로 측정되 었다. 각각의 안경을 2년간 착용한 후에 평균 등가구면 굴절력의 변화량은 A그룹에서 –1.22±0.56 D이었고, B그 룹에서는 –0.90±0.51 D를 보였다(p=0.010). 결론 : 8세에서 19세의 근시가 있는 초중고 학생은 2년 간 어린이 근시관리 누진렌즈를 착용한 후에 단초점렌즈 를 착용한 그룹에 비해 근시 진행이 지연되었다. 근시관리 안경렌즈의 성공적인 시장 정착을 위해서는 더욱 다양한 모집단을 장기 추적 관찰하여 그 효과를 연구한 자료가 필요하다고 생각된다.

Cyanobacteria Pseudanabaena strains are known to produce 2-MIB (odorous material) in freshwater systems, thereby causing problems in water use. However, their physiological responses to environmental factors in relation with 2-MIB production is not well explored. This study was conducted to evaluate the effect of temperature on the growth and 2-MIB production of Pseudanabaena redekei. The experimental cyanobacteria strains were separated from the Uiam Reservoir (North Han River) and cultured in the BG-11 medium. Temperature was set to 10, 15, 20, 25, and 30℃ for the experiment, in the reflection of the seasonal water temperature variation in situ. For each temperature treatment, cyanobacterial biomass (Chl-a) and 2-MIB concentration (intra-cellular and extra-cellular fractions) were measured every 2 days for 18 days. Both maximal growth and total 2-MIB production of P. redekei appeared at 30℃. While intra-cellular 2-MIB contents were similar (26~29 ng L-1) regardless of treated temperatures, extra-cellular 2-MIB concentration was higher only in high temperature conditions (25~30℃), indicating that the extents of 2-MIB biosynthesis and release by P. redekei vary with temperature. The 2-MIB productivity of P. redekei was much higher in low-temperature conditions (10~15℃) than high temperature conditions (25~30℃). This study demonstrated that temperature was a critical factor contributing to 2-MIB biosynthesis and its release in cell growth (r=0.605, p<0.01). These results are important to understand the dynamics of 2-MIB in the field and thereby provide basic information for managing odorous material in drinking water resources.

Cyanobacterial resting cells, such as akinetes, are important seed cells for cyanobacteria’s early development and bloom. Due to their importance, various methods have been attempted to isolate resting cells present in the sediment. Ludox is a solution mainly used for cell separation in marine sediments, but finding an accurate method for use in freshwater is difficult. This study compared the two most commonly used Ludox methods (direct sediment treatment and sediment distilled water suspension treatment). Furthermore, we proposed a highly efficient method for isolating cyanobacterial resting cells and eDNA amplification from freshwater sediments. Most of the resting cells found in the sediment were akinete to the Nostocale and were similar to those of Dolichospermum, Cylindrospermum, and Aphanizomenon. Twenty times more akinetes were found in the conical tube column using the sediment that had no treatment than in the sample treated by suspending the sediment in distilled water. Akinete separated through Ludox were mainly spread over the upper and lower layers in the column rather than concentrated at a specific depth in the column layer. The mibC, Geo, and 16S rDNA genes were successfully amplified using the sediment directly in the sample. However, the amplification products of all genes were not found in the sample in which the sediment was suspended in distilled water. Therefore, 5 g to 10 g of sediment is used without pretreatment when isolating cyanobacterial resting cells from freshwater sediment. Cell isolation and gene amplification efficiency are high when four times the volume of Ludox is added. The Ludox treatment method presented in this study isolates cyanobacterial resting cells in freshwater sediment, and the same efficiency may not appear in other biotas. Therefore, to apply Ludox to the separation of other biotas, it is necessary to conduct a pre-experiment to determine the sediment pretreatment method and the water layer where the target organism exists.

Environmental DNA (eDNA) can exist in both intracellular and extracellular forms in natural ecosystems. When targeting harmful cyanobacteria, extracellular eDNA indicates the presence of traces of cyanobacteria, while intracellular eDNA indicates the potential for cyanobacteria to occur. However, identifying the “actual” potential for harmful cyanobacteria to occur is difficult using the existing sediment eDNA analysis method, which uses silica beads and cannot distinguish between these two forms of eDNA. This study analyzes the applicability of a density gradient centrifugation method (Ludox method) that can selectively analyze intracellular eDNA in sediment to overcome the limitations of conventional sediment eDNA analysis. PCR was used to amplify the extracted eDNA based on the two different methods, and the relative amount of gene amplification was compared using electrophoresis and Image J application. While the conventional bead beating method uses sediment as it is to extract eDNA, it is unknown whether the mic gene amplified from eDNA exists in the cyanobacterial cell or only outside of the cell. However, since the Ludox method concentrates the intracellular eDNA of the sediment through filtration and density gradient, only the mic gene present in the cyanobacteria cells could be amplified. Furthermore, the bead beating method can analyze up to 1 g of sediment at a time, whereas the Ludox method can analyze 5 g to 30 g at a time. This gram of sediments makes it possible to search for even a small amount of mic gene that cannot be searched by conventional bead beating method. In this study, the Ludox method secured sufficient intracellular gene concentration and clearly distinguished intracellular and extracellular eDNA, enabling more accurate and detailed potential analysis. By using the Ludox method for environmental RNA expression and next-generation sequencing (NGS) of harmful cyanobacteria in the sediment, it will be possible to analyze the potential more realistically.

Oil spills have occurred throughout the years of industrialization and represent a global challenge as they affect vast areas of the ocean. The toxicity of crude oil to aquatic organisms has been extensively investigated, but the potential impacts of crude oil on vertebrate development remain largely unknown. Here, we investigated the effects of dispersants used in treating a recent oil spill, as well as that of crude oil, on vertebrates by using the zebrafish (Danio rerio) model species, which has been widely used in empirical studies of both early embryonic development and adult physiology. Chronic exposure to crude oil resulted in marked developmental abnormalities, including pericardial edema, abnormal trunk vessel development, retardation of axonal branching, and abnormal jaw development. Embryonic development was affected more severely by exposure to the oil-dispersant combination than to the oil alone. Thus, the zebrafish in vivo model system suggests that dispersant treatment can have detrimental developmental effects on vertebrates and its potential impact on marine life, as well as humans, should be carefully considered in clean-up efforts at the site of an oil spill.

Methanol as a carbon source in chemical vapor deposition (CVD) graphene has an advantage over methane and hydrogen in that we can avoid optimizing an etching reagent condition. Since methanol itself can easily decompose into hydrocarbon and water (an etching reagent) at high temperatures [1], the pressure and the temperature of methanol are the only parameters we have to handle. In this study, synthetic conditions for highly crystalline and large area graphene have been optimized by adjusting pressure and temperature; the effect of each parameter was analyzed systematically by Raman, scanning electron microscope, transmission electron microscope, atomic force microscope, four-point-probe measurement, and UV-Vis. Defect density of graphene, represented by D/G ratio in Raman, decreased with increasing temperature and decreasing pressure; it negatively affected electrical conductivity. From our process and various analyses, methanol CVD growth for graphene has been found to be a safe, cheap, easy, and simple method to produce high quality, large area, and continuous graphene films.

유방 자기공명영상검사 시 확산강조영상에서 발생하는 심장과 폐에 의한 불수의적 움직임 인공물과 감소된 영상영역 에코평면영상기법으로 발생하는 둘러겹침 인공물을 추가적인 사전포화기법을 사용하여 이를 저감화시키고자 하였다. 2014년 08월 1일부터 11월 30일까지 여성 환자 38명을 대상으로 하였으며 사용 장비로는 유방 검사에 최적화된 3.0T와 유방 전용 코일을 사용하였다. 영상의 평가와 분석은 정량적, 정성적 분석을 하였으며 통계적 유의성은 Paired T-test와 Wilcoxon rank test를 하였다. 결과적으로 추가적인 사전포화펄스의 사용으로 정량적인 평가에서는 병변에서 15.69%, 병변 근접 부위에서 13.72%, 지방에서 20.63%의 증가를 보였으며, 대조도 대 잡음비의 경우는 병변과 병변 근접 부위에서 10.58%, 병변과 지방 부위에서 12.03%의 증가로 나타났다. 정성적인 평가에서는 확산경사계수 0에서 22.05%, 1000에서 21.42%, 현성확산계수에서 16.10%의 증가로 나타났으며, 통계적 평가에서는 신호 대 잡음비와 대조도 잡음비, 확산경사계수와 현성확산계수에서 모두 유의한 결과로 나타났다(p<0.05). 따라서 사전포화펄스의 추가적인 사용으로 유방 자기공명영상 검사에서 확산강조영상 획득 시 위상 부호화 방향으로 발생하는 불수의적 움직임 인공물과 둘러겹침 인공물이 감소가 되어 최적의 영상을 얻을 수 있을 것으로 판단된다.