Search

Your search keyword '"Park AH"' showing total 1,452 results
Start Over Author "Park AH"
1,452 results on '"Park AH"'

1. Room-temperature decomposition of the ethaline deep eutectic solvent

Author

Yang, Julia H., Ooi, Amanda Whai Shin, Goodwin, Zachary A. H., Xie, Yu, Ding, Jingxuan, Falletta, Stefano, Park, Ah-Hyung Alissa, and Kozinsky, Boris

Subjects
Physics - Chemical Physics, Physics - Computational Physics
Abstract

Environmentally-benign, non-toxic electrolytes with combinatorial design spaces are excellent candidates for green solvents, green leaching agents, and carbon capture sources. Here, we examine one particular green solvent, ethaline, a 2:1 molar ratio of ethylene glycol and choline chloride. Despite its touted green credentials, we find partial decomposition of ethaline into toxic chloromethane and dimethylaminoethanol at room temperature, limiting its sustainable advantage. We experimentally characterize these decomposition products and computationally develop a general, quantum chemically-accurate workflow to understand decomposition. We find that fluctuations of the hydrogen bonds bind chloride near reaction sites, initiating the reaction between choline cations and chloride anions. In summary, in the design of green solvents, we do not recommend the use of choline chloride due to its susceptibility to undergo decomposition in strongly hydrogen-bound mixtures.

Published
2024

2. Carbon capture in polymer-based electrolytes

Author

Wang, Yang, Feric, Tony G, Tang, Jing, Fang, Chao, Hamilton, Sara T, Halat, David M, Wu, Bing, Celik, Hasan, Rim, Guanhe, DuBridge, Tara, Oshiro, Julianne, Wang, Rui, Park, Ah-Hyung Alissa, and Reimer, Jeffrey A

Subjects
Macromolecular and Materials Chemistry, Chemical Sciences, Physical Chemistry, Bioengineering, Nanotechnology, Climate Action
Abstract

Nanoparticle organic hybrid materials (NOHMs) have been proposed as excellent electrolytes for combined CO2 capture and electrochemical conversion due to their conductive nature and chemical tunability. However, CO2 capture behavior and transport properties of these electrolytes after CO2 capture have not yet been studied. Here, we use a variety of nuclear magnetic resonance (NMR) techniques to explore the carbon speciation and transport properties of branched polyethylenimine (PEI) and PEI-grafted silica nanoparticles (denoted as NOHM-I-PEI) after CO2 capture. Quantitative 13C NMR spectra collected at variable temperatures reveal that absorbed CO2 exists as carbamates (RHNCOO- or RR'NCOO-) and carbonate/bicarbonate (CO32-/HCO3-). The transport properties of PEI and NOHM-I-PEI studied using 1H pulsed-field-gradient NMR, combined with molecular dynamics simulations, demonstrate that coulombic interactions between negatively and positively charged chains dominate in PEI, while the self-diffusion in NOHM-I-PEI is dominated by silica nanoparticles. These results provide strategies for selecting adsorbed forms of carbon for electrochemical reduction.

Published
2024

4. Technologies to Capture CO$_2$ directly from Ambient Air

Author

Lee, Gahyun Annie, Shi, Xiaoyang, and Park, Ah-Hyung Alissa

Subjects
Physics - Chemical Physics
Abstract

Building a carbon-neutral world needs to remove the excess CO$_2$ that has already been dumped into the atmosphere. The sea, soil, vegetation, and rocks on Earth all naturally uptake CO$_2$ from the atmosphere. Human beings can accelerate these processes in specific ways. The review summarizes the present Direct Air Capture (DAC) technology that contribute to Negative Emissions. Research currently being done has suggested future perspectives and directions of various methods for Negative Emission. New generations of technologies have emerged as a result of recent advancements in surface chemistry, material synthesis, and engineering design. These technologies may influence the large-scale deployment of existing CO$_2$ capture technologies in the future.

Published
2022

5. Water-stable MOFs and Hydrophobically Encapsulated MOFs for CO2 Capture from Ambient Air and Wet Flue Gas

Author

Shi, Xiaoyang, Lee, Gahyun Annie, Liu, Shuohan, Kim, Dongjae, Alahmed, Ammar, Jamal, Aqil, Wang, Lei, and Park, Ah-Hyung Alissa

Subjects
Condensed Matter - Materials Science
Abstract

The extra CO2 that has already been released into the atmosphere has to be removed in order to create a world that is carbon neutral. Technologies have been created to remove carbon dioxide from wet flue gas or even directly from ambient air, however these technologies are not widely deployed yet. New generations of creative CO2 capture sorbents have been produced as a consequence of recent improvements in material assembly and surface chemistry. We summarize recent progress on water-stable and encapsulated metal-organic frameworks (MOFs) for CO2 capture under a wide range of environmental and operating conditions. In particular, newly developed water-stable MOFs and hydrophobic coating technologies are discussed with insights into their materials discovery and the synergistic effects between different components of these hybrid sorbent systems. The future perspectives and directions of water-stable and encapsulated MOFs are also given for Direct Air Capture of CO2 and CO2 capture from wet flue gas.

Published
2022

8. Crif1 deficiency in dopamine neurons triggers early-onset parkinsonism

Author

Heo, Jun Young, Park, Ah Hyung, Lee, Min Joung, Ryu, Min Jeong, Kim, Yong Kyung, Jang, Yun Seon, Kim, Soo Jeong, Shin, So Yeon, Son, Hyo Jin, Stein, Thor D., Huh, Yang Hoon, Chung, Sookja K., Choi, Song Yi, Kim, Jin Man, Hwang, Onyou, Shong, Minho, Hyeon, Seung Jae, Lee, Junghee, Ryu, Hoon, Kim, Daesoo, and Kweon, Gi Ryang

Published
2023
Full Text
View/download PDF

32. The utility of ultrafast MRI and conventional DCE-MRI for predicting histologic aggressiveness in patients with breast cancer.

Author

Kim, Seong Gwang, Park, Ah Young, Jung, Hae Kyoung, Ko, Kyung Hee, and Kim, Yunju

Subjects
*CONTRAST-enhanced magnetic resonance imaging, *TRIPLE-negative breast cancer, *MAGNETIC resonance imaging, *PROGNOSIS, *INTRACLASS correlation
Abstract

Background: Prediction of histologic prognostic markers is important for determining management strategy and predicting prognosis. Purpose: To identify important features of ultrafast and conventional dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) that can predict histopathologic prognostic markers in patients with breast cancer. Material and Methods: Preoperative MRI scans of 158 consecutive women (mean age = 54.0 years; age range = 29–86 years) with 163 breast cancers between February 2021 and August 2022 were retrospectively reviewed. Inter-observer agreements for ultrafast MRI parameters were analyzed by two radiologists. The qualitative and quantitative MRI parameters were correlated with histopathologic prognostic markers including molecular subtypes and histologic invasiveness. Results: Inter-observer agreements for ultrafast MRI parameters were excellent (intraclass correlation coefficients of area under the kinetic curve [AUC], maximum slope [MS], maximum enhancement [ME], and slope = 0.987, 0.844, 0.822, and 0.760, respectively). Triple-negative breast cancers (TNBC) were significantly associated with rim enhancement (odds ratio [OR] = 9.4, P = 0.003) and peritumoral edema (OR = 17.9, P = 0.002), compared to luminal cancers. Invasive cancers were associated with lesion type-mass, increased delayed washout, angiovolume, ME, slope, MS, and AUC, compared to in situ cancers. In regression analysis, the combination of MS (>46.2%/s) (OR = 5.7, P = 0.046) and delayed washout (>17.5%) (OR = 17.6, P = 0.01), and that of AUC (>27,410.3) (OR = 9.6, P = 0.04), delayed washout (>17.5%) (OR = 8.9, P = 0.009), and lesion-type mass (OR = 4.6, P = 0.04) were predictive of histologic invasiveness. Conclusion: Conventional DCE-MRI with ultrafast imaging can provide useful information for predicting histologic underestimation and aggressive molecular subtype. MS and AUC on ultrafast MRI can be potential imaging markers for predicting histologic upgrade from DCIS to invasive cancer with high reliability. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

33. Cigarette Sales to Underage Youth in Seoul, South Korea: Findings From a Mystery Shopping Study.

Author

Park, Ah-hyun, Park, Jinbeom, Choi, Jihae, Noh, Songwhi, and Choo, Jina

Subjects
CROSS-sectional method, RESEARCH funding, SHOPPING, MULTIPLE regression analysis, HEALTH policy, LEGAL status of sales personnel, DESCRIPTIVE statistics, SALES personnel, TEENAGERS' conduct of life, TOBACCO products, PUBLIC health, DATA analysis software, CONVENIENCE stores
Abstract

This study aimed to identify the rates of cigarette sales to underage youth and the factors associated with these sales using a mystery shopping technique. Of the convenience stores selling cigarettes in Seoul, South Korea, 2600 were sampled in 2019 and 2020. Personal and environmental factors were independent variables. Cigarette sales to underage youth were the outcome variable, defined as cases where a seller sold cigarettes to a youth shopper. A multiple logistic regression analysis was performed. Rates of cigarette sales to underage youth were 17.9% in 2019 and 16.3% in 2020, significantly higher when the seller was younger and the store was located in a central area. Administrative actions are needed to enforce strong warnings and training guidelines for convenience store sellers. Differentiation in surveillance intensity based on the location of convenience stores in Seoul is also recommended. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

46. Stable and predictive functional domain selection with application to brain images

Author

Park, Ah Yeon, Aston, John A. D., and Ferraty, Frederic

Subjects
Statistics - Applications
Abstract

Motivated by increasing trends of relating brain images to a clinical outcome of interest, we propose a functional domain selection (FuDoS) method that effectively selects subregions of the brain associated with the outcome. View each individual's brain as a 3D functional object, the statistical aim is to distinguish the region where a regression coefficient $\beta(t)=0$ from $\beta(t)\neq0$, where $t$ denotes spatial location. FuDoS is composed of two stages of estimation. We first segment the brain into several small parts based on the correlation structure. Then, potential subsets are built using the obtained segments and their predictive performance are evaluated to select the best subset, augmented by a stability selection criterion. We conduct extensive simulations both for 1D and 3D functional data, and evaluate its effectiveness in selecting the true subregion. We also investigate predictive ability of the selected stable regions. To find the brain regions related to cognitive ability, FuDoS is applied to the ADNI's PET data. Due to the induced sparseness, the results naturally provide more interpretable information about the relations between the regions and the outcome. Moreover, the selected regions from our analysis show high associations with the expected anatomical brain areas known to have memory-related functions.

Published
2016

Catalog

Books, media, physical & digital resources
See catalog results