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Effects of Water Chemistry on Aggregation and Soil Adsorption of Silver Nanoparticles
Bae, Sujin,Hwang, Yu Sik,Lee, Yong-Ju,Lee, Sung-Kyu The Korean Society of Environmental Toxicology 2013 환경독성보건학회지 Vol.28 No.-
Objectives In this study, we investigated the influence of ionic strength and natural organic matter (NOM) on aggregation and soil adsorption of citrate-coated silver nanoparticles (AgNPs). Methods Time-resolved dynamic light scattering measurements and batch adsorption experiments were used to study their aggregation and soil adsorption behaviors, respectively. Results The aggregation rate of AgNPs increased with increasing ionic strength and decreasing NOM concentration. At higher ionic strength, the AgNPs were unstable, and thus tended to be adsorbed to the soil, while increased NOM concentration hindered soil adsorption. To understand the varying behaviors of AgNPs depending on the environmental factors, particle zeta potentials were also measured as a function of ionic strength and NOM concentration. The magnitude of particle zeta potential became more negative with decreasing ionic strength and increasing NOM concentration. These results imply that the aggregation and soil adsorption behavior of AgNPs were mainly controlled by electrical double-layer repulsion consistent with the Derjaguin-Landau-Verwey-Overbeek theory. Conclusions This study found that the aggregation and soil adsorption behavior of AgNPs are closely associated with environmental factors such as ionic strength and NOM and suggested that assessing the environmental fate and transport of nanoparticles requires a thorough understanding of particle-particle interaction mechanisms.
Sujin Bae,John J. Lenhart,Yu Sik Hwang 대한환경공학회 2022 Environmental Engineering Research Vol.27 No.6
An accurate assessment of the fate and transport of engineered nanoparticles (ENPs) in aquatic environments hinges on developing an understanding of interaction between ENPs and natural colloids. In this study, we investigated the effects of pH and natural organic matter (NOM) on homoaggregation of CeO₂ nanoparticles and their heteroaggregation with montmorillonite clay minerals. Time-resolved dynamic light scattering (TR-DLS) was employed to investigate the aggregation kinetics as function of electrolyte concentration in both homo- and heteroaggregation scenarios. The surface charge of CeO₂ nanoparticles changed from positive to negative with pH increase while montmorillonite was negatively charged over the range of pH 4−11. At low pH, the critical coagulation concentration (CCC) of the montmorillonite-CeO₂ mixtures shifted to a lower electrolyte concentration when compared to the homogenous system, indicating the negatively charged montmorillonite reduced the stability of positively charged CeO₂ via heteroaggregation. In contrast, at high pH, the mixtures were stable because both montmorillonite and CeO₂ nanoparticles were negatively charged. The presence of humic acid stabilized the systems against homo- and heteroaggregation. Our results suggest that the complex interactions between ENPs, natural colloids, and NOM should be considered to better understand the fate and transport of ENPs in realistic aquatic environments.
Bae, Sujin,Han, Doug Hyun,Jung, Jaebum,Nam, Ki Chun,Renshaw, Perry F. Akadémiai Kiadó 2017 JOURNAL OF BEHAVIOURAL ADDICTIONS Vol.6 No.4
<P><B>Background and aims</B></P><P>Given the similarities in clinical symptoms, Internet gaming disorder (IGD) is thought to be diagnostically similar to Internet-based gambling disorder (ibGD). However, cognitive enhancement and educational use of Internet gaming suggest that the two disorders derive from different neurobiological mechanisms. The goal of this study was to compare subjects with ibGD to those with IGD.</P><P><B>Methods</B></P><P>Fifteen patients with IGD, 14 patients with ibGD, and 15 healthy control subjects were included in this study. Resting-state functional magnetic resonance imaging data for all participants were acquired using a 3.0 Tesla MRI scanner (Philips, Eindhoven, The Netherlands). Seed-based analyses, the three brain networks of default mode, cognitive control, and reward circuitry, were performed.</P><P><B>Results</B></P><P>Both IGD and ibGD groups demonstrated decreased functional connectivity (FC) within the default-mode network (DMN) (family-wise error <I>p</I> < .001) compared with healthy control subjects. However, the IGD group demonstrated increased FC within the cognitive network compared with both the ibGD (<I>p</I> < .01) and healthy control groups (<I>p</I> < .01). In contrast, the ibGD group demonstrated increased FC within the reward circuitry compared with both IGD (<I>p</I> < .01) and healthy control subjects (<I>p</I> < .01).</P><P><B>Discussion and conclusions</B></P><P>The IGD and ibGD groups shared the characteristic of decreased FC in the DMN. However, the IGD group demonstrated increased FC within the cognitive network compared with both ibGD and healthy comparison groups.</P>