Comparison of Antibiotic Resistance Removal Efficiencies Using Ozone Disinfection under Different pH and Suspended Solids and Humic Substance Concentrations

Pak, Gijung,Salcedo, Dennis Espineli,Lee, Hansaem,Oh, Junsik,Maeng, Sung Kyu,Song, Kyung Guen,Hong, Seok Won,Kim, Hyun-Chul,Chandran, Kartik,Kim, Sungpyo American Chemical Society 2016 Environmental science & technology Vol.50 No.14

<P>This study mainly evaluated the effectiveness of ozonation toward the enhancement of the removal efficiencies of antibiotic-resistant bacteria (ARB), pB10 plasmid transfer, and pB10 plasmids under different pH and suspended solids (SS) and humic acid concentrations. First, chlorination was tested as a reference disinfection process. Chlorination at a very high dose concentration of Cl-2 (75 mg L-1) and a long contact time (10 min) were required to achieve approximately 90% ARB and pB10 plasmid transfer removal efficiencies. However, even these stringent conditions only resulted in a 78.8% reduction of pB10 plasmid concentrations. In case of ozonation, the estimated CT (concentration x contact time) value (at C-0 = 7 mg L-1) for achieving 4-log pB10 plasmid removal efficiency was 127.15 mg.min L-1, which was 1.04- and 1.25-fold higher than those required for ARB (122.73 mg-min L-1) and a model nonantibiotic resistant bacterial strain, E. coli K-12, (101.4 mg.min L-1), respectively. In preventing pB10 plasmid transfer, ozonation achieved better performance under conditions of higher concentrations of humic acid and lower pH. Our study results demonstrated that the applicability of CT concept in practice, conventionally used for disinfection, might not be appropriate for antibiotic resistance control in the wastewater treatment process. Further studies should be conducted in wastewater engineering on how to implement multiple barriers including disinfection to prevent ARB and ARG discharge into the environment.</P>

Balance Deficit and Brain Connectivity in Children with Attention-Deficit/Hyperactivity Disorder

SunMi Kim,GiJung Hyun,TaeWoon Jung,YoungDon Son,InHee Cho,BaikSeok Kee,DougHyun Han 대한신경정신의학회 2017 PSYCHIATRY INVESTIGATION Vol.14 No.4

Objective-We aimed to assess disturbances in postural and gait balance and functional connectivity within the brain regions controlling balance in children with attention-deficit/hyperactivity disorder (ADHD). Methods-Thirteen children with ADHD and 13 age- and sex-matched controls were recruited. Gait balance was assessed by the difference in the center of pressure (COP) between the left and right foot, as well as the difference in plantar pressure between the left and right foot during gait. Neuroimaging data were acquired using a 3.0 Tesla MRI scanner. Functional connectivity between the vermis of the cerebellum and all other brain regionswas assessed. Results-The difference in plantar pressure between the left foot and right foot in the ADHD group was greater than that observed in the control group. The average COP jerk score of the right foot in the ADHD group was higher than that observed in the control group. A higher functional connectivity between the cerebellum and the right middle frontal gyrus (premotor cortex) and medial frontal gyrus (cingulate gyrus) was observed in the control group relative to the ADHD group. In the ADHD group, the difference in plantar pressure between the left and right foot was also negatively correlated with the beta-value within the middle frontal gyrus. Conclusion-Children with ADHD had disturbance of balance as assessed by plantar pressure. Decreased brain connectivity from the cerebellum to the premotor cortex and anterior cingulate was associated with disturbances of posture and balance in children with ADHD.

Flexible and Stable Omniphobic Surfaces Based on Biomimetic Repulsive Air-Spring Structures

Seo, Dongkwon,Cha, Suk-kyong,Kim, Gijung,Shin, Hyunku,Hong, Soonwoo,Cho, Yang Hyun,Chun, Honggu,Choi, Yeonho American Chemical Society 2019 ACS APPLIED MATERIALS & INTERFACES Vol.11 No.6

<P>In artificial biological circulation systems such as extracorporeal membrane oxygenation, surface wettability is a critical factor in blood clotting problems. Therefore, to prevent blood from clotting, omniphobic surfaces are required to repel both hydrophilic and oleophilic liquids and reduce surface friction. However, most omniphobic surfaces have been fabricated by combining chemical reagent coating and physical structures and/or using rigid materials such as silicon and metal. It is almost impossible for chemicals to be used in the omniphobic surface for biomedical devices due to durability and toxicity. Moreover, a flexible and stable omniphobic surface is difficult to be fabricated by using conventional rigid materials. This study demonstrates a flexible and stable omniphobic surface by mimicking the re-entrant structure of springtail’s skin. Our surface consists of a thin nanohole membrane on supporting microstructures. This structure traps air under the membrane, which can repel the liquid on the surface like a spring and increase the contact angle regardless of liquid type. By theoretical wetting model and simulation, we confirm that the omniphobic property is derived from air trapped in the structure. Also, our surface well maintains the omniphobicity under a highly pressurized condition. As a proof of our concept and one of the real-life applications, blood experiments are performed with our flat and curved surfaces and the results including contact angle, advancing/receding angles, and residuals show significant omniphobicity. We hope that our omniphobic surface has a significant impact on blood-contacting biomedical applications.</P> [FIG OMISSION]</BR>

Considering the effect of groundwater on bioretention using the Storm Water Management Model

Kim, Hwansuk,Mallari, Kristine Joy B.,Baek, Jongrak,Pak, Gijung,Choi, Hyun Il,Yoon, Jaeyoung Elsevier 2019 Journal of environmental management Vol.231 No.-

<P><B>Abstract</B></P> <P>The Storm Water Management Model (SWMM), with its recently released low impact development (LID) module, is among several models used for the performance evaluation of LID facilities in reducing runoff and pollutants. Modeling is often difficult because of the variety of factors affecting the LID system. Among these factors, the effect of groundwater can be important in the LID modeling results due to the possibility of its interaction with LID. In this study, the performance of the SWMM-LID controls in predicting runoff from bioretention cells was evaluated for a site under groundwater influence. In addition, for considering the groundwater effect in the model, this study explores the utility of the SWMM groundwater model in predicting runoff under groundwater influence. Runoff from the considered watershed draining into the bioretention cells was well-simulated with very favorable performance statistic values (r<SUP>2</SUP> = 0.96, NSE = 0.94, % difference = 2.76). However, comparison of simulated with observed runoff from bioretention cells produced weaker statistical values (r<SUP>2</SUP> = 0.69, NSE = 0.65, % difference = 18.22), which is thought to be due to the presence of events affected by groundwater interference. Removal of these events and recalibration were able to improve the overall results, suggesting that the influence of groundwater should be taken into account for better LID modeling of the study site. In order to consider the groundwater influence, the SWMM groundwater model was used in tandem with LID controls to provide an additional influent source to bioretention cells. This resulted in a good fit for two events which were thought to be impacted by groundwater (events in which outflow exceeded inflow) and overall better performance (r<SUP>2</SUP> = 0.95, NSE = 0.95, % difference = 3.49) compared to the results obtained by using only LID controls. In conclusion, the SWMM groundwater model can help deal with groundwater-impacted events. However, for better representation of the phenomenon, the LID module itself needs to be improved to account for direct interaction with groundwater.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We calibrated and validated a bioretention system under groundwater influence using SWMM LID control. </LI> <LI> Data used for calibration and validation was screened from International Stormwater BMP Database. </LI> <LI> The effect of groundwater was found to be negative on the outflow modeling results for the events with high antecedent moisture condition. </LI> <LI> The use of the SWMM's groundwater model was able to represent well the impact of groundwater on the outflow from bioretention. </LI> </UL> </P>