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Regional Gray Matter Volume Related to High Occupational Stress in Firefighters
Lee Deokjong,Kim Woojin,Lee Jung Eun,Lee Junghan,Lee Seung-Koo,Chang Sei-Jin,Jeung Da Yee,Hyun Dae-Sung,Ryu Hye-Yoon,Kim Changsoo,Jung Young-Chul 대한의학회 2021 Journal of Korean medical science Vol.36 No.50
Background: Firefighters inevitably encounter emotionally and physically stressful situations at work. Even firefighters without diagnosed post-traumatic stress disorder receive clinical attention because the nature of the profession exposes them to repetitive trauma and high occupational stress. This study investigated gray matter abnormalities related to high occupational stress in firefighters using voxel-based morphometry (VBM) and surface-based morphometry (SBM). Methods: We assessed 115 subjects (112 males and 3 females) using magnetic resonance imaging and evaluated occupational stress by the Korean Occupational Stress Scale-26 (KOSS-26). Subjects were classified into highly or lowly stressed groups based on the median value of the KOSS-26. Results: In VBM analysis, we found that firefighters with high occupational stress had lower gray matter volume (GMV) in both sides of the insula, the left amygdala, the right medial prefrontal cortex (mPFC), and the anterior cingulate cortex than firefighters with low occupational stress. In SBM analysis based on regions of interest, the GMV of the bilateral insula and right mPFC were also lower in the highly stressed group. Within the highly stressed group, low GMV of the insula was significantly correlated with the length of service (left: r = −0.347, P = 0.009; right: r = −0.333, P = 0.012). Conclusion: Our findings suggest that regional GMV abnormalities are related to occupational stress. Regional gray matter abnormalities and related emotional dysregulation may contribute to firefighter susceptibility to burnout.
Oxygen-Controlled Seed Layer in DC Sputter-Deposited ZnO:Al Substrate for Si Thin-Film Solar Cells
Seung-Yoon Lee,Taehyun Hwang,Woojin Lee,Sangheon Lee,Hongsik Choi,Seh-Won Ahn,Heon-Min Lee,Byungwoo Park IEEE 2015 IEEE journal of photovoltaics Vol.5 No.2
<P>Oxygen-controlled seed layer in Al-doped ZnO (ZnO:Al) thin films deposited by the industrially compatible dynamic dc magnetron sputter results in both enhanced electron mobilities and appropriate etched morphologies for the Si thin-film solar cells. At the relatively low deposition temperature of 300 °C, optimized ZnO:Al film grown on the seed layer has the carrier mobility of 45 cm<SUP>2</SUP>/V·s and proper postetching morphology with around 1-2-μm crater size. Reduced angular distribution of the (002) grains analyzed by the diffraction rocking curve is shown as the key structural feature for the improved carrier mobility. Finally, the performance of the microcrystalline Si solar cell on the developed ZnO:Al substrate shows high-efficiency potential of the tandem solar cell adapting this transparent conductive oxide substrate.</P>
Nanostructural analysis of ZnO:Al thin films for carrier-transport mechanisms
Seung-Yoon Lee,Woojin Lee,남창우,Jongmin Kim,Sujin Byun,Taehyun Hwang,Byung-Kee Lee,Young Il Jang,Sungeun Lee,Heon Min Lee,박병우 한국물리학회 2013 Current Applied Physics Vol.13 No.4
The carrier mobility of sputter-deposited Al-doped ZnO transparent-conducting (ZnO:Al) thin films was controlled between 22 and 48 cm2/Vs by varying the ZnO:Al seed layer. The statistical distribution of the [001] grain misorientation was characterized from the X-ray diffraction rocking curve in the range from 0.043 (2.5) to 0.179 rad (10.2). The grain-boundary energy barriers (Eb) from Seto’s model [1] clearly exhibit linear dependence on the grain-boundary misorientation angle (u) according to the equation Eb ¼ 78 4 þ 173 32 u meV.
Cocrystal Formation via Resorcinol-Urea Interactions: Naringenin and Carbamazepine
Lee, CheongCheon,Cho, A. Young,Yoon, Woojin,Yun, Hoseop,Kang, Jeong Won,Lee, Jonghwi The American Chemical Society 2019 CRYSTAL GROWTH AND DESIGN Vol.19 No.7
<P>Improving the stability, bioavailability, and processability of active pharmaceutical ingredients (APIs) has been the key research goal in the field of pharmaceutical crystallization. Cocrystallization has been considered as an effective route to achieve this goal, and intense research over decades has revealed cocrystals of many APIs. However, most cocrystal formers have been designed based primarily on their molecular interactions not their health benefits. Herein, we choose naringenin (N), a natural flavonoid, as a novel cocrystal former as it has many health efficacies and the ability to form specific interactions. At a 1:1 stoichiometric ratio, N successfully forms a cocrystal with carbamazepine (CBZ), whose plasma concentration is known to be improved by natural flavonoids such as N. The resorcinol functional group of N and the urea functional group of CBZ are connected through hydrogen bonds, and the improved stability of the cocrystal seems to originate from this structure. The melting temperature of the cocrystal is 262 °C, which is higher than those of CBZ and N, and the better stability of the cocrystal is further confirmed by the observation of enhanced hydration stability (up to 30 days at 93% RH). This novel strategy of cocrystallization using natural flavonoids could improve the commercialization potential of API cocrystals.</P><P>Natural flavonoids exhibit unique molecular interactions via resorcinol, pyrogallol, or catechol groups. We found that naringenin, which has a resorcinol group, could form a unique cocrystal with carbamazepine, which has a urea group. This presents a new direction for the development of drug cocrystals.</P> [FIG OMISSION]</BR>
An R<sub>2</sub>* model of white matter for fiber orientation and myelin concentration
Lee, Jingu,Shin, Hyeong-Geol,Jung, Woojin,Nam, Yoonho,Oh, Se-Hong,Lee, Jongho Elsevier 2017 NeuroImage Vol.162 No.-
<P><B>Abstract</B></P> <P>Myelin, which consists of lipid bilayers, is one of the major constituents of white matter in the brain and has been suggested as a primary source of magnetic susceptibility contrasts. In this study, a new R<SUB>2</SUB>* model that simultaneously explains the effects of fiber orientation and myelin concentration is proposed and tested. In addition, a new approach that produces R<SUB>2</SUB>* maps without the effects of myelin is suggested. Experimental results demonstrate that the model reveals a high goodness of fit for the R<SUB>2</SUB>* distribution of white matter compared to a model that explains either fiber orientation or myelin concentration. The proposed R<SUB>2</SUB>* map shows a relatively uniform spatial distribution of R<SUB>2</SUB>* compared to the uncorrected R<SUB>2</SUB>* map and the fiber orientation or myelin concentration corrected R<SUB>2</SUB>* map.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A new R2* model for fiber orientation and myelin concentration is proposed. </LI> <LI> The model explains the total myelin effects on R2* in white matter. </LI> <LI> The myelin effects on R2* were subtracted to generate a new myelin-removed R2* map. </LI> <LI> The corrected R2* map reveals reduced R2* heterogeneity in white matter. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>