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Ahn, Sug-Joon,Cho, Eun-Jung,Oh, Sung-Suk,Lim, Bum-Soon Informa Healthcare 2012 Acta odontologica scandinavica Vol.70 No.6
<P><B><I>Objective.</I></B> To investigate the effects of various orthodontic bonding steps on biofilm formation of <I>Streptococcus mutans</I> in the presence of saliva. <B><I>Materials and methods:</I></B> Hydroxyapatite (HA) and orthodontic adhesive (AD) disks were prepared to a uniform size. HA disks were etched with 37% phosphoric acid gel in the etched group (HE). In the primed group (HP), Transbond XT primer was applied to the etched HA surface and light-cured. For biofilm formation, <I>Streptococcus mutans</I> was grown on each specimen in a biofilm medium with either glucose or sucrose in the presence of fluid-phase UWS (F-UWS) or surface adsorbed saliva (S-UWS). The adherent bacteria were quantified by enumeration of the total viable counts of bacteria. Biofilms formed on each surface were examined by scanning electron microscopy. <B><I>Results.</I></B> When glucose was used, both F-UWS and S-UWS suppressed biofilm formation of <I>S. mutans.</I> Compared to HA and HE, biofilm formation was significantly inhibited on HP and AD in the presence of glucose. Biofilm-forming patterns that were inhibited by saliva were restored in a sucrose-containing medium. F-UWS promoted biofilm formation on HA and HE, while S-UWS significantly promoted biofilm formation on HP. <I>S. mutans</I> developed biofilm better on HA and HE than on AD when sucrose was used as the sole carbohydrate source. <B><I>Conclusions.</I></B> This study suggests that the biofilm development by <I>S. mutans</I> is significantly influenced by the orthodontic bonding procedure. Biofilm formation of <I>S. mutans</I> was inhibited on AD more than other surfaces, irrespective of the presence of saliva or a carbohydrate source.</P>
Ahn Yura,Koo Hyun Jung,Kang Joon-Won,Choi Won Jin,Kim Dae-Hee,Song Jong-Min,Kang Duk-Hyun,Song Jae-Kwan,Kim Joon Bum,Jung Sung-Ho,Choo Suk Jung,Chung Cheol Hyun,Lee Jae Won,Yang Dong Hyun 대한영상의학회 2021 Korean Journal of Radiology Vol.22 No.8
Objective: To investigate the prognostic value of preoperative cardiac magnetic resonance imaging (MRI) for long-term major adverse cardiac and cerebrovascular events (MACCEs) in patients undergoing tricuspid valve (TV) surgery for functional tricuspid regurgitation (TR). Materials and Methods: The preoperative cardiac MR images, New York Heart Association functional class, comorbidities, and clinical events of 78 patients (median [interquartile range], 59 [51–66.3] years, 28.2% male) who underwent TV surgery for functional TR were comprehensively reviewed. Cox proportional hazards analyses were performed to assess the associations of clinical and imaging parameters with MACCEs and all-cause mortality. Results: For the median follow-up duration of 5.4 years (interquartile range, 1.2–6.6), MACCEs and all-cause mortality were 51.3% and 23.1%, respectively. The right ventricular (RV) end-systolic volume index (ESVI) and the systolic RV mass index (RVMI) were higher in patients with MACCEs than those without them (77 vs. 68 mL/m2, p = 0.048; 23.5 vs. 18.0%, p = 0.011, respectively). A high RV ESVI was associated with all-cause mortality (hazard ratio [HR] per value of 10 higher ESVI = 1.10, p = 0.03). A high RVMI was also associated with all-cause mortality (HR per increase of 5 mL/m2 RVMI = 1.75, p < 0.001). After adjusting for age and sex, only RVMI remained a significant predictor of MACCEs and all-cause mortality (p < 0.05 for both). After adjusting for multiple clinical variables, RVMI remained significantly associated with all-cause mortality (p = 0.005). Conclusion: RVMI measured on preoperative cardiac MRI was an independent predictor of long-term outcomes in patients who underwent TV surgery for functional TR.
Sang Bum Suh,Keun Jae Ahn,Hye Jin Chung,Ji Youn Suh,Sung Bin Cho 대한의학레이저학회 2020 MEDICAL LASERS Vol.9 No.1
Human fibroblast-derived multi-peptide factors (MPFs) have been used during treatments with energy-delivering modalities to enhance energy-induced tissue reactions. Human fibroblast-derived MPFs, which include a range of growth factors and chemoattractive factors, activate and recruit fibroblasts and endothelial cells, as well as promote extracellular matrix deposition, all of which are crucial to wound repair. Interestingly, fibroblasts from different species or anatomical sites exhibit distinct transcriptional properties with high heterogeneity. In addition, the patterns of MPF secretion can differ under a range of experimental conditions. Therefore, the use of allogeneic fibroblasts and proper cultivation thereof are necessary to obtain MPFs that can enhance the epithelial-mesenchymal interactions during wound repair. Moreover, energy-delivering devices should be selected according to evidence demonstrating their therapeutic efficacy and safety on a pathological skin condition and the major target skin layers. This paper reviewed the histologic patterns of post-treatment tissue reactions elicited by several energy sources, including non-ablative and ablative fractional lasers, intense focused ultrasound, non-invasive and invasive radiofrequency, picosecond-domain lasers, and argon and nitrogen plasma. The possible role of the immediate application of human fibroblast-derived MPFs during wound repair was proposed.
( Sang Bum An ),( Eun Su Choi ),( Won Sik Ahn ) 대한마취과학회 2011 Korean Journal of Anesthesiology Vol.60 No.4
Background: Three kinds of conditions should be considered to reduce free hemoglobin production using an autologous cell salvage device. They are the negative suction pressure, the size of suction tip, and the air contact during suction. We want to examine which condition is the most important factor to produce free hemoglobin. Methods: One pack of red blood cell and one pack of fresh frozen plasma with the same blood type were mixed. They were aspirated based on the two suction pressure (-150 mmHg or -300 mmHg), three sizes of suction tips, and the two conditions of air contact, in which the suction tip was located in the surface of blood or in the middle of the blood. Seven ml sized EDTA tube was used to collect 5 ml blood. All the procedure repeated ten times. Free hemoglobin, total hemoglobin, and hematocrit were measured. Hemolysis ratio was calculated with following formula. Hemolysis ratio = (new free hemoglobin production) × (100-hematocrit) / (total hemoglobin). Results: Free hemoglobin production and hemolysis ratio were increased when the suction tip was positioned in the surface than when it was in the middle of the blood. The pressure of negative suction and three kinds of the suction tips did not influence the production of free hemoglobin nor the hemolysis ratio. Conclusions: The air contact is the most important factor to reduce hemolysis using autologous cell salvage device. Suction pressure or suction tip diameter have little influence to produce hemolysis. (Korean J Anesthesiol 2011; 60: 266-271)
Thermo-optic Effects of Bragg Grating Optical Temperature Sensor
Ahn, Kook-Chan,Lee, Sang-Mae,Lee, Gwang-Seok,Park, Seung-Bum The Korean Society for Aeronautical and Space Scie 2002 International Journal of Aeronautical and Space Sc Vol.3 No.2
This paper demonstrates a comparison of linear and nonlinear analyses for thermo-optic effects of optical temperature sensor based on the etched silica-based planar waveguide Bragg grating. Topics include theoretical analyses and experiment of the etched planar waveguide Bragg grating optical temperature sensor. Theoretical models with nonlinear than linear temperature effect for the grating response based on waveguide and plate deformation theories agree with experiments to within acceptable tolerance.
Ahn, Hye-Ran,Cho, Sung-Bum,Chung, Ik Joo,Kweon, Sun-Seog Elsevier 2018 American journal of infection control Vol.46 No.3
<P><B>Background</B></P> <P>Hepatitis is the most important cause of hepatocellular carcinoma in Korea. This study evaluated the socioeconomic differences in self- and family awareness of hepatitis status among hepatitis B and C carriers and their cohabitants in rural Korea.</P> <P><B>Methods</B></P> <P>In total, 5,017 randomly selected rural residents participated in a seroepidemiologic and questionnaire survey. We found 326 hepatitis B surface antigen carriers or hepatitis C antibody carriers and 310 family members cohabiting with members of this group.</P> <P><B>Results</B></P> <P>Among the hepatitis B carriers and their family members, 48.1% were aware of their own status and 36.7% were aware of their cohabitant's hepatitis status, respectively. Only 28.1% of the hepatitis C carriers were aware of their own status, and only 23.3% of their cohabiting family members knew about their family member's hepatitis C status. A multivariate analysis including health-related factors, such as alcohol consumption, family history of liver disease, and recent acupuncture history, found that self-awareness was significantly lower in the older group and significantly higher in the more educated and higher-income groups. Family awareness was also increased in those working in salaried jobs.</P> <P><B>Conclusions</B></P> <P>Socioeconomic disparities in awareness of hepatitis status were found among hepatitis carriers and their families.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Among the hepatitis B and C carriers, 48.1% and 28.1%, respectively, know their serologic status. </LI> <LI> Among the cohabitants of hepatitis B and C carriers, 36.7% and 23.3%, respectively, know the hepatitis status of their family members. </LI> <LI> Self-awareness and family awareness were higher among the subjects of high socioeconomic status. </LI> </UL> </P>
Ahn, Wook,Lim, Sung Nam,Lee, Dong Un,Kim, Kwang-Bum,Chen, Zhongwei,Yeon, Sun-Hwa The Royal Society of Chemistry 2015 Journal of Materials Chemistry A Vol.3 No.18
<▼1><P>A sulfur–MWCNT composite battery containing a protective layer based on a MMT-coated separator was examined for its electrochemical properties.</P></▼1><▼2><P>To improve the cycle life of Li–S rechargeable batteries, chemically dispersed nanocarbon materials are usually employed as adsorbents and conductive matrices for cathodic nano-sized sulfur materials. Herein, a new assembly for Li–S cells is developed by introducing a montmorillonite (MMT) ceramic protective film to form an ion selective separator. The effect of the MMT-coated separator and the reaction mechanism between MMT and polysulfides are characterized <I>via</I> Raman and zeta potential analyses. The utilization of the MMT coated separator enables the minimization of the shuttle effect by preventing the diffusion of polysulfide. The best discharge capacity and cycle life are obtained with the MMT coated separator in a sulfur–MWCNT composite cathode, resulting in a discharge capacity of 1382 mA h g<SUP>−1</SUP> at a current density of 100 mA g<SUP>−1</SUP> and 924 mA h g<SUP>−1</SUP> after 200 cycles. The Li–S cell using the nano-sized sulfur–MWCNT composite and the MMT-coated separator shows significantly excellent electrochemical performance.</P></▼2>
A nonvolatile memory based on reversible phase changes between fcc and hcp
Ahn, Dong-Ho,Kang, Dae-Hwan,Cheong, Byung-ki,Kwon, Hyuk-Soon,Kwon, Min-Ho,Lee, Tae-Yeon,Jeong, Jeung-hyun,Lee, Taek Sung,Kim, In Ho,Kim, Ki-Bum IEEE 2005 IEEE electron device letters Vol.26 No.5
A nonvolatile memory technology utilizing reversible changes between fcc and hcp crystalline phases is proposed. In this new type of phase-change memory, data are stored in different forms of crystalline phases of (Ge<SUB>1</SUB>Sb<SUB>2</SUB>Te<SUB>4</SUB>)<SUB>0.8</SUB>(Sn<SUB>1</SUB>Bi<SUB>2</SUB>Te<SUB>4</SUB>)<SUB>0.2</SUB> chalcogenide alloy. RESET operation produces the less conductive metastable fcc phase via melt-quenching from the more conductive stable hcp phase and SET operation involves a phase change from fcc directly to hcp. Both RESET and SET operations can be completed as fast as 70 ns with large changes in cell resistance.