Publications by authors named "Hyunjung Shin"

99 Publications

Polypharmacy Side effect Prediction with Enhanced Interpretability Based on Graph Feature Attention Network.

Bioinformatics 2021 Mar 14. Epub 2021 Mar 14.

Department of Industrial Engineering, Ajou University, Wonchun-dong, Yeongtong-gu, Suwon 443-749, South Korea.

Motivation: Polypharmacy side effects should be carefully considered for new drug development. However, considering all the complex drug-drug interactions that cause polypharma-cy side effects is challenging. Recently, graph neural network (GNN) models have handled these complex interactions successfully and shown great predictive perfor-mance. Nevertheless, the GNN models have difficulty providing intelligible factors of the prediction for biomedical and pharmaceutical domain experts.

Method: A novel approach, graph feature attention network (GFAN), is presented for inter-pretable prediction of polypharmacy side effects by emphasizing target genes differ-ently. To artificially simulate polypharmacy situations, where two different drugs are taken together, we formulated a node classification problem by using the concept of line graph in graph theory.

Results: Experiments with benchmark datasets validated interpretability of the GFAN and demonstrated competitive performance with the graph attention network in a previous work. And the specific cases in the polypharmacy side effect prediction experiments showed that the GFAN model is capable of very sensitively extracting the target genes for each side effect prediction.

Availability And Implementation: https://github.com/SunjooBang/Polypharmacy-side-effect-prediction.
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http://dx.doi.org/10.1093/bioinformatics/btab174DOI Listing
March 2021

Unusual Hole Transfer Dynamics of the NiO Layer in Methylammonium Lead Tri-iodide Absorber Solar Cells.

J Phys Chem Lett 2021 Mar 12;12(11):2770-2779. Epub 2021 Mar 12.

Department of Physics, Department of Energy Engineering, Hanyang University, Seoul 04763, Republic of Korea.

Nickel oxides (NiO) as hole transport layers (HTLs) in inverted-type perovskite solar cells (PSCs) have been widely studied mainly because of their high stability under illumination. Increases in the power conversion efficiency (PCE) with NiO HTLs have been presented in numerous reports, although the photoluminescence (PL) quenching behavior does not coincide with the PCE increase. The dynamics of the charge carrier transport between the NiO HTLs and the organic-inorganic halide perovskite absorbers is not clearly understood yet and quite unusual, in contrast to organic/polymerics HTLs. We deposited NiO HTLs with precisely controlled thicknesses by atomic layer deposition (ALD) and studied their photovoltaic performances and hole transfer characteristics. Ground state bleaching (GSB) recovery was observed by ultrafast transient absorption spectroscopy (TAS), which suggested that backward hole injection occurred between the perovskites and NiO HTLs, so that the uncommon PL behaviors can be clearly explained. Backward hole injection from the NiO HTL to the perovskite absorber originated from their similar valence band (VB) energy positions. The thickness increase of the NiO HTLs induced VB sharing, which caused a red-shift of the photoinduced hole absorption spectrum in near-infrared (NIR) femtosecond TAS and a decrease in the PL intensity. Our studies on inorganic metal oxide transport layers, NiO in this work, with a thickness dependence and the comparison with organic layers provide a better understanding of the interfacial carrier dynamics in PSCs.
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http://dx.doi.org/10.1021/acs.jpclett.1c00335DOI Listing
March 2021

Charge Trapping in Amorphous Dielectrics for Secure Charge Storage.

ACS Appl Mater Interfaces 2021 Mar 23;13(9):11507-11514. Epub 2021 Feb 23.

Department of Energy Science, Sungkyunkwan University, 2066 Seobu-ro, Suwon-si, Gyeonggi-do 16419, Korea.

The fundamental scientific ingredient in the current information society is charge trapping in dielectric materials. The current data storage device known as NAND flash is based on charge trapping in silicon nitride, and it has been widely used in semiconductor processing. The growth of information in human society has incessantly driven storage devices with higher information density. The evolution of higher density NAND flash has been advanced based on memory cell stacking, which necessitates an upscaling of the dielectric constant of charge-trapping dielectrics in the future. In this study, we demonstrate that the amorphous phase is a prerequisite for secure charge trapping in future high-dielectric constant charge-trapping dielectric materials, in which a lower process temperature is required. Additionally, we demonstrate that a composition-graded dielectric thin film is a promising solution for the low-temperature fabrication of NAND flash.
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http://dx.doi.org/10.1021/acsami.0c23083DOI Listing
March 2021

High-Valent Iodoplumbate-Rich Perovskite Precursor Solution Solar Illumination for Reproducible Power Conversion Efficiency.

J Phys Chem Lett 2021 Feb 9;12(6):1676-1682. Epub 2021 Feb 9.

Department of Chemical and Biomolecular Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Republic of Korea.

The power conversion efficiency (PCE) of solution-processed organic-inorganic hybrid perovskite solar cells has been drastically improved. Despite this considerable progress, systematic research on precursor solution chemistry and its effects on photovoltaic parameters has been limited thus far. Herein, we report on the tracking of changes in chemical species in a precursor solution under solar illumination and investigate the correlation between the equilibrium change and the corresponding perovskite film formation. The illuminated perovskite precursors display a higher density of high-valent iodoplumbate, where the resulting perovskite film exhibits reduced defect density with uniform film formation. Conclusively, the perovskite solar cells prepared by the photoaged precursor solution demonstrate not only improved average PCE but also enhanced reproducibility with a narrow PCE distribution. This discovery shows robust control of perovskite precursor solutions from a simple treatment and suggests that the resulting uniform film may be applicable to various halide perovskite-based devices.
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http://dx.doi.org/10.1021/acs.jpclett.0c03849DOI Listing
February 2021

Dynamic structural property of organic-inorganic metal halide perovskite.

iScience 2021 Jan 24;24(1):101959. Epub 2020 Dec 24.

Department of Energy Science and Nature Inspired Materials Processing Research Center, Sungkyunkwan University, Suwon 16419, Republic of Korea.

Unique organic-inorganic hybrid semiconducting materials have made a remarkable breakthrough in new class of photovoltaics (PVs). Organic-inorganic metal (Pb and/or Sn) halides (-I, -Br, and -Cl) are the semiconducting absorber with the crystal structure of the famous "Perovskite". It is widely called "perovskite solar cells (PSCs)" in PV society. Now, the power conversion efficiency (PCE) of PSCs is recorded in 25.5%. Prototypical composition of the absorbers is (A = methylammonium [MA], formamidinium [FA], and Cs), (M = Pb and/or Sn), and (X = I, Br, and Cl) in the form of perovskite AMX. Since the report on the stable all solid-state PSCs in 2012, the average annual growth rate of PCE is well over ∼10%. Such an outstanding PV performance attracts huge number of scientists in our research society. Their chemical as well as physical properties are dramatically different from monocrystalline Si, GaAs, other III-IV semiconductors, and many oxides with the crystal structure of perovskite. In this review, different fundamental aspects, in particular, the dynamic properties of A site cationic molecules and PbI octahedrons linked with their corners, from other semiconducting and dielectric materials are reviewed and summarized. Upon discussing unique properties, perspectives on the promising PV applications based on the comprehension in dynamic nature of the orientation in A site molecule and PbI octahedron tilting will be given.
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http://dx.doi.org/10.1016/j.isci.2020.101959DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7788097PMC
January 2021

Dementia key gene identification with multi-layered SNP-gene-disease network.

Bioinformatics 2020 12;36(Suppl_2):i831-i839

Department of Artificial Intelligence, Department of Industrial Engineering.

Motivation: Recently, various approaches for diagnosing and treating dementia have received significant attention, especially in identifying key genes that are crucial for dementia. If the mutations of such key genes could be tracked, it would be possible to predict the time of onset of dementia and significantly aid in developing drugs to treat dementia. However, gene finding involves tremendous cost, time and effort. To alleviate these problems, research on utilizing computational biology to decrease the search space of candidate genes is actively conducted.

In this study, we propose a framework in which diseases, genes and single-nucleotide polymorphisms are represented by a layered network, and key genes are predicted by a machine learning algorithm. The algorithm utilizes a network-based semi-supervised learning model that can be applied to layered data structures.

Results: The proposed method was applied to a dataset extracted from public databases related to diseases and genes with data collected from 186 patients. A portion of key genes obtained using the proposed method was verified in silico through PubMed literature, and the remaining genes were left as possible candidate genes.

Availability And Implementation: The code for the framework will be available at http://www.alphaminers.net/.

Supplementary Information: Supplementary data are available at Bioinformatics online.
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http://dx.doi.org/10.1093/bioinformatics/btaa814DOI Listing
December 2020

Stem cell spheroid engineering with osteoinductive and ROS scavenging nanofibers for bone regeneration.

Biofabrication 2020 Dec 21. Epub 2020 Dec 21.

Department of Bioengineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul, 04763, Korea (the Republic of).

Stem cell spheroids have been widely investigated to accelerate bone tissue regeneartion. However, the directed differentiation of stem cells into osteoblastic lineage and the prevention of cells from damage by reactive oxygen species (ROS) remain challenge. Here, we developed osteoinductive and ROS scavenging extracellular matrix (ECM)-mimicking synthetic fibers based on epigallocatechin gallate (EGCG) coating. They were then utilized to fabricate engineered spheroids with human adipose-derived stem cells (hADSCs) for bone tissue regeneation. The EGCG-mineral fibers (EMF) effectively conferred osteoinductive and ROS scavenging signals on the hADSCs within spheroids, demonstrating relative upregulation of antioxidant genes (SOD-1 (25.8±2.1) and GPX-1 (3.3±0.1) and greater level of expression of osteogenic markers, RUNX2 (5.8±0.1) and OPN (5.9±0.1), compared to hADSCs in the spheroids without EMF. The in vitro overexpression of osteogenic genes from hADSCs was achieved from absence of osteogenic supplenments. Furthermore, in vivo transplantation of hADSCs spheroids with the EMF significantly promoted calvarial bone regeneration (48.39±9.24%) compared to that from defect only (17.38±6.63%), suggesting that the stem cell spheroid biofabrication system with our novel mineralization method described here is a promising tool for bone tissue regeneration.
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http://dx.doi.org/10.1088/1758-5090/abd56cDOI Listing
December 2020

Corrections to "Comorbidity Scoring With Causal Disease Networks".

IEEE/ACM Trans Comput Biol Bioinform 2020 Nov-Dec;17(6):2196

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http://dx.doi.org/10.1109/TCBB.2020.3000846DOI Listing
December 2020

Osteogenic Properties of Novel Methylsulfonylmethane-Coated Hydroxyapatite Scaffold.

Int J Mol Sci 2020 Nov 12;21(22). Epub 2020 Nov 12.

Department and Research Institute of Dental Biomaterials and Bioengineering, Yonsei University College of Dentistry, Seoul 03722, Korea.

Despite numerous advantages of using porous hydroxyapatite (HAp) scaffolds in bone regeneration, the material is limited in terms of osteoinduction. In this study, the porous scaffold made from nanosized HAp was coated with different concentrations of osteoinductive aqueous methylsulfonylmethane (MSM) solution (2.5, 5, 10, and 20%) and the corresponding MH scaffolds were referred to as MH2.5, MH5, MH10, and MH20, respectively. The results showed that all MH scaffolds resulted in burst release of MSM for up to 7 d. Cellular experiments were conducted using MC3T3-E1 preosteoblast cells, which showed no significant difference between the MH2.5 scaffold and the control with respect to the rate of cell proliferation ( > 0.05). There was no significant difference between each group at day 4 for alkaline phosphatase (ALP) activity, though the MH2.5 group showed higher level of activity than other groups at day 10. Calcium deposition, using alizarin red staining, showed that cell mineralization was significantly higher in the MH2.5 scaffold than that in the HAp scaffold ( < 0.0001). This study indicated that the MH2.5 scaffold has potential for both osteoinduction and osteoconduction in bone regeneration.
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http://dx.doi.org/10.3390/ijms21228501DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7696815PMC
November 2020

Role of Electrostatics in the Heterogeneous Interaction of Two-Dimensional Engineered MoS Nanosheets and Natural Clay Colloids: Influence of pH and Natural Organic Matter.

Environ Sci Technol 2021 01 10;55(2):919-929. Epub 2020 Nov 10.

Department of Civil, Architectural and Environmental Engineering, The University of Texas at Austin, Austin, Texas 78712, United States.

Few-layered molybdenum disulfide (MoS) nanosheets are poised to be at the core of low-voltage electronic device development. Upon environmental release, these two-dimensional (2D) structures can interact with abundant natural geocolloids. This study probes the role of dimensionality in modulating the aggregation behavior of 2D MoS nanosheets with plate-like geocolloids (i.e., homoionized kaolinite and montmorillonite clays). MoS nanosheets were exfoliated using an ethanol/water mixture, and aggregation kinetics were investigated with time-resolved dynamic light scattering at low monovalent salt concentrations and at three pH levels, in the presence and absence of Suwannee River humic acid (SRHA). Results indicate that pH and particle ratios are key to modulating the stability of MoS/clay systems. At pH 4, aggregation of MoS increased with increasing MoS/clay ratios and approached maximum values of 0.09 and 0.06 nm/s in the binary systems with montmorillonite and kaolinite, respectively. Electrostatic attraction facilitates heteroaggregation at pH values of 4 and 6; differences in the clay structures (i.e., face-face or face-edge aggregates) might explain the resulting MoS/clay aggregate configurations, which were probed via the evolution of particle size distribution. The presence of only 0.1 mg/L SRHA drastically suppresses the heteroaggregation propensity of MoS nanosheets with geocolloids (to less than 0.01 nm/s at all pH values tested). The high stability of these heterogeneous systems under environmentally relevant conditions can increase the likelihood for cellular uptake and long-distance transport of MoS.
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http://dx.doi.org/10.1021/acs.est.0c03580DOI Listing
January 2021

On the Crystallization of Hydroxyapatite under Hydrothermal Conditions: Role of Sebacic Acid as an Additive.

ACS Omega 2020 Oct 16;5(42):27204-27210. Epub 2020 Oct 16.

Nature Inspired Materials Processing Research Center, Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea.

Hydroxyapatite (HAp) is a major inorganic component in bone minerals and is often used for bone tissue engineering. Herein, we synthesized HAp using sebacic acid as an additive at different pH values by a hydrothermal method. Sebacic acid, which has two carboxyl group ends of the carbonate chain, binds with Ca ions during the hydrothermal process to become a crystal nucleation site in (001) and at the same time could act as an inhibitor in a specific direction [i.e., (110)] for the HAp crystal growth. Sebacic acid and the hydroxyl ion (OH) are competitively attracted to the ()-plane of HAp. Depending on the pH condition, the crystal growth resulted in different morphologies depending on the ratio of sebacic acid and hydroxide ions. It was confirmed through Fourier-transform infrared spectroscopy and Raman spectroscopy that dicalcium phosphate anhydrous with HPO was produced under acidic conditions and HAp was produced under neutral and basic conditions. The plate- and nanorod-HAp crystals' preferential growth along the -axis, which were obtained under neutral and basic conditions, was analyzed by transmission electron microscopy. Growth control in the -axis direction of HAp is necessary for the understanding of crystallization of bone minerals because the mineral inside the collagen fibrils in bone tissue also shows a -axis orientation.
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http://dx.doi.org/10.1021/acsomega.0c03297DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7594153PMC
October 2020

Characteristics of 10-Methacryloyloxidecyl Dihydrogen Phosphate Monomer in Self-Etching Two-Bottled Dental Adhesive System: Comparison with Commercial Products.

Materials (Basel) 2020 Aug 12;13(16). Epub 2020 Aug 12.

Nature Inspired Materials Processing Research Center, Department of Energy Science, Sungkyunkwan University, Suwon-si 16419, Korea.

Dentin bonding is a key in restorative dentistry. Here, we developed a self-etching two-bottle adhesive system containing 10-methacryloyloxidecyl dihydrogen phosphate monomer (MDP) and the physical, mechanical, and biocompatible properties were evaluated. The characteristics of MDP were analyzed using nuclear magnetic resonance (NMR). Tests for water sorption and solubility, the shear-bond strengths to dentin and enamel, and cytotoxicity were performed. The newly-blended experimental group showed the lowest thickness and water sorption and solubility values. The shear bond strength of enamel and dentin were comparable to control groups (the three other products were Clearfil, UniFil, and AdheSE). All test groups showed 60% of cell viability. In this study, the properties of the newly-synthesized adhesive are comparable with the others. The fundamental goal of this study is to get the MDP patent released, as it is intended for domestic production. For this purpose, this dentin adhesive was developed and compared with the commercial product.
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http://dx.doi.org/10.3390/ma13163553DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7475973PMC
August 2020

High-Efficiency Perovskite Solar Cells.

Chem Rev 2020 Aug 28;120(15):7867-7918. Epub 2020 Jul 28.

School of Chemical Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea.

With rapid progress in a power conversion efficiency (PCE) to reach 25%, metal halide perovskite-based solar cells became a game-changer in a photovoltaic performance race. Triggered by the development of the solid-state perovskite solar cell in 2012, intense follow-up research works on structure design, materials chemistry, process engineering, and device physics have contributed to the revolutionary evolution of the solid-state perovskite solar cell to be a strong candidate for a next-generation solar energy harvester. The high efficiency in combination with the low cost of materials and processes are the selling points of this cell over commercial silicon or other organic and inorganic solar cells. The characteristic features of perovskite materials may enable further advancement of the PCE beyond those afforded by the silicon solar cells, toward the Shockley-Queisser limit. This review summarizes the fundamentals behind the optoelectronic properties of perovskite materials, as well as the important approaches to fabricating high-efficiency perovskite solar cells. Furthermore, possible next-generation strategies for enhancing the PCE over the Shockley-Queisser limit are discussed.
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http://dx.doi.org/10.1021/acs.chemrev.0c00107DOI Listing
August 2020

Tailored 2D/3D Halide Perovskite Heterointerface for Substantially Enhanced Endurance in Conducting Bridge Resistive Switching Memory.

ACS Appl Mater Interfaces 2020 Apr 24;12(14):17039-17045. Epub 2020 Mar 24.

School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea.

Hybrid organic-inorganic halide perovskites (HPs) have garnered significant attention for use in resistive switching (RS) memory devices due to their low cost, low operation voltage, high on/off ratio, and excellent mechanical properties. However, the HP-based RS memory devices continue to face several challenges owing to the short endurance and stability of the HP film. Herein, two-dimensional/three-dimensional (2D/3D) perovskite heterojunction films were prepared via a low-temperature all-solution process and their RS behavior was investigated for the first time. The 2D/3D perovskite RS devices exhibited excellent performance with an endurance of 2700 cycles, a high on/off ratio of 10, and an operation speed of 640 μs. The calculated thermally assisted ion hopping activation energy and the results of the time-of-flight secondary ion mass spectroscopy demonstrated that the 2D perovskite layer could efficiently prevent the Ag ion migration into the 3D perovskite film. Moreover, we found that owing to its high thermal conductivity, the 2D perovskite can control the rupture of the Ag conductive filament. Thus, the 2D perovskite layer enhances endurance by controlling both Ag migration and filament rupture. Hence, this study provides an alternate strategy for improving endurance of HP-based RS memory devices.
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http://dx.doi.org/10.1021/acsami.9b22918DOI Listing
April 2020

Effects of Perioperative Magnesium Sulfate Administration on Postoperative Chronic Knee Pain in Patients Undergoing Total Knee Arthroplasty: A Retrospective Evaluation.

J Clin Med 2019 Dec 17;8(12). Epub 2019 Dec 17.

Department of Anesthesiology and Pain Medicine, Seoul National University Bundang Hospital, Seongnam 13620, Korea.

We aimed to investigate whether perioperative magnesium sulfate administration was associated with the incidence of chronic persistent postoperative pain (PPP) following total knee arthroplasty (TKA). This retrospective observational study was performed at a single tertiary academic hospital. We reviewed the medical records of adult patients who were admitted between August 2012 and July 2017. Patients who received magnesium sulfate during surgery were the magnesium group. The presence of PPP, one year after TKA, was evaluated using a binary logistic regression analysis. A total of 924 patients were included in the analysis, and 148 patients (16.0%) experienced PPP one year after TKA. In the multivariable model, the magnesium group had a 62% lower rate of PPP one year after TKA compared to the control group (odds ratio (OR): 0.38, 95% confidence interval (CI): 0.16 to 0.90; = 0.027). This finding was similar in the sensitivity analysis using propensity score adjustment (OR: 0.38, 95% CI: 0.16 to 0.93; = 0.036). We showed that perioperative magnesium sulfate administration was associated with a lower rate of PPP one year after TKA. Our results suggest that magnesium sulfate administered perioperatively is effective for the alleviation of acute and chronic pain after surgery.
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http://dx.doi.org/10.3390/jcm8122231DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6947579PMC
December 2019

The translational network for metabolic disease - from protein interaction to disease co-occurrence.

BMC Bioinformatics 2019 Nov 13;20(1):576. Epub 2019 Nov 13.

Department of Industrial Engineering, Ajou University, 206, World cup-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do, 16499, Republic of Korea.

Background: The recent advances in human disease network have provided insights into establishing the relationships between the genotypes and phenotypes of diseases. In spite of the great progress, it yet remains as only a map of topologies between diseases, but not being able to be a pragmatic diagnostic/prognostic tool in medicine. It can further evolve from a map to a translational tool if it equips with a function of scoring that measures the likelihoods of the association between diseases. Then, a physician, when practicing on a patient, can suggest several diseases that are highly likely to co-occur with a primary disease according to the scores. In this study, we propose a method of implementing 'n-of-1 utility' (n potential diseases of one patient) to human disease network-the translational disease network.

Results: We first construct a disease network by introducing the notion of walk in graph theory to protein-protein interaction network, and then provide a scoring algorithm quantifying the likelihoods of disease co-occurrence given a primary disease. Metabolic diseases, that are highly prevalent but have found only a few associations in previous studies, are chosen as entries of the network.

Conclusions: The proposed method substantially increased connectivity between metabolic diseases and provided scores of co-occurring diseases. The increase in connectivity turned the disease network info-richer. The result lifted the AUC of random guessing up to 0.72 and appeared to be concordant with the existing literatures on disease comorbidity.
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http://dx.doi.org/10.1186/s12859-019-3106-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6854734PMC
November 2019

In Operando Stacking of Reduced Graphene Oxide for Active Hydrogen Evolution.

ACS Appl Mater Interfaces 2019 Nov 11;11(46):43460-43465. Epub 2019 Nov 11.

Department of Energy Science , Sungkyunkwan University , Suwon 16419 , Korea.

Despite the remarkable electronic and mechanical properties of graphene, improving the catalytic activity of the atomically flat, inert, and stable carbon network remains a challenging issue in both fundamental and application studies. In particular, the adsorption of most molecules and ions, including hydrogen (H or H), on graphene is not favorable, underlining the challenge for an efficient electrochemical catalytic reaction on graphene. Various defects, edges, and functionalization have been suggested to resolve the catalytic issue in graphene, but cost-effectiveness and active catalysis with graphene have not been achieved yet. Here, we introduce dynamic stacking of reduced graphene oxide (rGO) with spontaneously generated hydrogen bubbles to form an efficient electrochemical catalyst with a graphene derivative; the in operando stacking of rGO, without using a high-temperature-based heteroatom doping process or plasma treatment, creates a large catalytic surface area with optimized edges and acidic groups in the rGO. Thus, the uniquely formed stable carbon network achieves active hydrogen evolution with a Tafel slope of 39 mV·dec and a double layer capacitance of 12.41 mF·cm, which breaks the conventional limit of graphene-based catalysis, suggesting a promising strategy for metal-free catalyst engineering and hydrogen production.
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http://dx.doi.org/10.1021/acsami.9b11619DOI Listing
November 2019

Heterojunction Photoanode of Atomic-Layer-Deposited MoS on Single-Crystalline CdS Nanorod Arrays.

ACS Appl Mater Interfaces 2019 Oct 3;11(41):37586-37594. Epub 2019 Oct 3.

Department of Energy Science , Sungkyunkwan University , Suwon 440-746 , South Korea.

Cadmium sulfide (CdS) is a semiconducting absorber for photoelectrochemical (PEC) hydrogen production with suitable electronic band structures. However, it suffers from severe photocorrosion and rapid charge recombination during the desired PEC reactions. Herein, we describe the identification of the optimal junction thickness of CdS/MoS core/sheath heterojunction nanostructures by employing atomic layer deposition (ALD) techniques. ALD-grown MoS sheath layers with different thicknesses were realized on single-crystalline CdS nanorod (NR) arrays on transparent conducting oxide substrates. We further monitored the resulting solar H evolution performance with our heterojunction photoanodes. The results showed that the junction thickness of MoS plays a key role in the reduction of photocorrosion and the enhanced photocurrent density by optimizing the charge separation. A better saturation photocurrent (∼46%) was obtained with the 7 nm-thick MoS@CdS NRs than that with the bare CdS NRs. Moreover, the external quantum efficiency was increased twofold over that of the pristine CdS NRs. The ALD-grown MoS@CdS heterojunction structures provides an efficient and versatile platform for hydrogen production when combining ALD-grown MoS with ideal semiconducting absorbers.
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http://dx.doi.org/10.1021/acsami.9b11178DOI Listing
October 2019

Dementia Patient Segmentation Using EMR Data Visualization: A Design Study.

Int J Environ Res Public Health 2019 09 16;16(18). Epub 2019 Sep 16.

Department of Digital Media, Ajou University, Suwon 16499, Korea.

(1) Background: The Electronic Medical Record system, which is a digital medical record management architecture, is critical for reliable medical research. It facilitates the investigation of disease patterns and efficient treatment via collaboration with data scientists. (2) Methods: In this study, we present multidimensional visual tools for the analysis of multidimensional datasets via a combination of 3-dimensional radial coordinate visualization (3D RadVis) and many-objective optimization (e.g., Parallel Coordinates). Also, we propose a user-driven research design to facilitate visualization. We followed a design process to (1) understand the demands of domain experts, (2) define the problems based on relevant works, (3) design visualization, (4) implement visualization, and (5) enable qualitative evaluation by domain experts. (3) Results: This study provides clinical insight into dementia based on EMR data via visual analysis. Results of a case study based on questionnaires surveying daily living activities indicated that daily behaviors influenced the progression of dementia. (4) Conclusions: This study provides a visual analytical tool to support cluster segmentation. Using this tool, we segmented dementia patients into clusters and interpreted the behavioral patterns of each group. This study contributes to biomedical data interpretation based on a visual approach.
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http://dx.doi.org/10.3390/ijerph16183438DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6765847PMC
September 2019

Grain Boundary Healing of Organic-Inorganic Halide Perovskites for Moisture Stability.

Nano Lett 2019 Sep 20;19(9):6498-6505. Epub 2019 Aug 20.

Department of Chemical and Biomolecular Engineering , Yonsei University , 50 Yonsei-ro , Seodaemun-gu, Seoul 03722 , Republic of Korea.

Although organic-inorganic halide perovskite (OIHP)-based photovoltaics have high photoconversion efficiency (PCE), their poor humidity stability prevents commercialization. To overcome this critical hurdle, focusing on the grain boundary (GB) of OIHPs, which is the main humidity penetration channel, is crucial. Herein, pressure-induced crystallization of OIHP films prepared with controlled mold geometries is demonstrated as a GB-healing technique to obtain high moisture stability. When exposed to 85% RH at 30 °C, OIHP films fabricated by pressure-induced crystallization have enhanced moisture stability due to the enlarged OIHP grain size and low-angle GBs. The crystallographic and optical properties indicate the effect of applying pressure onto OIHP films in terms of moisture stability. The photovoltaic devices with pressure-induced crystallization exhibited dramatically stabilized performance and sustained over 0.95 normalized PCE after 200 h at 40% RH and 30 °C.
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http://dx.doi.org/10.1021/acs.nanolett.9b02721DOI Listing
September 2019

Drug repurposing with network reinforcement.

BMC Bioinformatics 2019 Jul 24;20(Suppl 13):383. Epub 2019 Jul 24.

Department of Industrial Engineering, Ajou University, 206, World cup-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do, 16499, Republic of Korea.

Background: Drug repurposing has been motivated to ameliorate low probability of success in drug discovery. For the recent decade, many in silico attempts have received primary attention as a first step to alleviate the high cost and longevity. Such study has taken benefits of abundance, variety, and easy accessibility of pharmaceutical and biomedical data. Utilizing the research friendly environment, in this study, we propose a network-based machine learning algorithm for drug repurposing. Particularly, we show a framework on how to construct a drug network, and how to strengthen the network by employing multiple/heterogeneous types of data.

Results: The proposed method consists of three steps. First, we construct a drug network from drug-target protein information. Then, the drug network is reinforced by utilizing drug-drug interaction knowledge on bioactivity and/or medication from literature databases. Through the enhancement, the number of connected nodes and the number of edges between them become more abundant and informative, which can lead to a higher probability of success of in silico drug repurposing. The enhanced network recommends candidate drugs for repurposing through drug scoring. The scoring process utilizes graph-based semi-supervised learning to determine the priority of recommendations.

Conclusions: The drug network is reinforced in terms of the coverage and connections of drugs: the drug coverage increases from 4738 to 5442, and the drug-drug associations as well from 808,752 to 982,361. Along with the network enhancement, drug recommendation becomes more reliable: AUC of 0.89 was achieved lifted from 0.79. For typical cases, 11 recommended drugs were shown for vascular dementia: amantadine, conotoxin GV, tenocyclidine, cycloeucine, etc.
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http://dx.doi.org/10.1186/s12859-019-2858-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6651901PMC
July 2019

Obovatol inhibits NLRP3, AIM2, and non-canonical inflammasome activation.

Phytomedicine 2019 Oct 4;63:153019. Epub 2019 Jul 4.

College of Veterinary Medicine and Institute of Veterinary Science, Kangwon National University, Chuncheon, Gangwon, 24341, Republic of Korea. Electronic address:

Background: Obovatol, a biphenolic chemical originating from Magnolia obovata, has been utilized as a traditional medicine for the treatment of inflammatory diseases. Inflammasome induces maturation of inflammatory cytokines in response to intracellular danger signals, and its dysregulation induces inflammatory diseases.

Purpose: The effect of obovatol on inflammasome activation has not been reported, although its anti-inflammatory properties have been studied.

Study Design/methods: Obovatol was treated to macrophages with inflammasome triggers, and secretions of interleukin (IL)-1β, IL-18, and caspase-1 were measured as readouts of inflammasome activation. In addition, Asc pyroptosome formation, caspase-1 activity, and mitochondrial reactive oxygen species (ROS) production were analyzed in mechanical studies. Anti-inflammasome properties of obovatol were confirmed in an animal model.

Results: Obovatol inhibited NLRP3, AIM2, and non-canonical inflammasomes through inhibition of Asc pyroptosome formation and mitochondrial ROS generation. In addition, obovatol disrupted the priming step of inflammasome activation and inhibited transcription of inflammatory cytokines. In mice, obovatol attenuated serum IL-1β elevation in response to monosodium urate crystals.

Conclusion: Obovatol is suggested as an inhibitor of NLRP3, AIM2, and non-canonical inflammasomes.
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http://dx.doi.org/10.1016/j.phymed.2019.153019DOI Listing
October 2019

Inference on chains of disease progression based on disease networks.

PLoS One 2019 28;14(6):e0218871. Epub 2019 Jun 28.

Department of Industrial Engineering, Ajou University, Yeongtong-gu, Suwon, South Korea.

Motivation: Disease progression originates from the concept that an individual disease may go through different changes as it evolves, and such changes can cause new diseases. It is important to find a progression between diseases since knowing the prior-posterior relationship beforehand can prevent further complications or evolutions to other diseases. Furthermore, the series of progressions can be represented in the form of a chain, which enables us to readily infer successive influences from one disease to another after many passages through other diseases.

Methods: In this paper, we propose a systematic approach for finding a disease progression chain from a source disease to a target one via exploring a disease network. The network is constructed based on various sets of biomedical data. To find the most influential progression chains, the k-shortest path search algorithm is employed. The most representative algorithms such as A*, Dijkstra, and Yen's are incorporated into the proposed method.

Results: A disease network consisting of 3,302 diseases was constructed based on four sources of biomedical data: disease-protein relations, biological pathways, clinical history, and biomedical literature information. The last three sets of data contain prior-posterior information, and they endow directionality on the edges of the network. The results were interesting and informative: for example, when colitis and respiratory insufficiency were set as a source disease and a target one, respectively, five progression chains were found within several seconds (when k = 5). Each chain was provided with a progression score, which indicates the strength of plausibility relative to others. Similarly, the proposed method can be expanded to any pair of source-target diseases in the network. This can be utilized as a preliminary tool for inferring complications or progressions between diseases.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0218871PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6599221PMC
February 2020

Cost for treatment and follow-up of thyroid cancer increases according to the severity of disease.

Head Neck 2019 07 19;41(7):2376-2379. Epub 2019 Feb 19.

Department of Surgery, Thyroid Cancer Center, Gangnam Severance Hospital, Institute of Refractory Thyroid Cancer, Yonsei University College of Medicine, Seoul, Korea.

Background: The aim of this study was to provide an analysis of thyroid cancer-related health care costs over a 5-year period, according to the extent of thyroid surgery.

Methods: The study included 33 patients from our institutional database who underwent thyroid cancer surgery in 2010. Patients were divided into four groups based on surgical extent: (1) hemithyroidectomy, (2) total thyroidectomy, (3) total thyroidectomy with ipsilateral radical neck dissection, and (4) total thyroidectomy with bilateral radical neck dissection and mediastinal dissection. Costs for admission and outpatient follow-up for 5 years were analyzed.

Results: Costs for outpatient follow-up and admission, and overall cost increased with increasing stage of disease and increasing extent of thyroid surgery. Patients who underwent only hemithyroidectomy had the lowest costs for outpatient follow-up and admission, as well as the lowest overall cost.

Conclusion: Over the 5-year follow-up period, surgery performed at an early disease stage was the most cost-effective.
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http://dx.doi.org/10.1002/hed.25706DOI Listing
July 2019

Disease Pathway Cut for Multi-Target drugs.

BMC Bioinformatics 2019 Feb 13;20(1):74. Epub 2019 Feb 13.

Department of Industrial Engineering, Ajou University, 206, World cup-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do, 16499, Republic of Korea.

Background: Biomarker discovery studies have been moving the focus from a single target gene to a set of target genes. However, the number of target genes in a drug should be minimum to avoid drug side-effect or toxicity. But still, the set of target genes should effectively block all possible paths of disease progression.

Methods: In this article, we propose a network based computational analysis for target gene identification for multi-target drugs. The min-cut algorithm is employed to cut all the paths from onset genes to apoptotic genes on a disease pathway. If the pathway network is completely disconnected, development of disease will not further go on. The genes corresponding to the end points of the cutting edges are identified as candidate target genes for a multi-target drug.

Results And Conclusions: The proposed method was applied to 10 disease pathways. In total, thirty candidate genes were suggested. The result was validated with gene set enrichment analysis software, PubMed literature review and de facto drug targets.
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http://dx.doi.org/10.1186/s12859-019-2638-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6483058PMC
February 2019

Atomic layer deposition for efficient and stable perovskite solar cells.

Chem Commun (Camb) 2019 Feb;55(17):2403-2416

Department of Energy Science, Sungkyunkwan University, Suwon 440-746, Republic of Korea.

Organic-inorganic hybrid metal halides are now the most attractive photovoltaic absorber materials, typically, methylammonium lead triiodides (MAPbI3). These unique semiconducting materials as absorbers demonstrate a remarkably improved power conversion efficiency of over 20% and now with a certified efficiency of 23.3%. Considering the Shockley-Queisser limit and their bandgaps, there is still much room to increase the efficiency. Stable devices with reproducibility and long-term use are essential for their commercialization. Atomic layer deposition (ALD) is a powerful technique to deposit high-quality thin films with excellent thickness accuracy and conformality, as well as with no pin-holes in a large area at low temperatures. ALD could be an ideal tool for efficient and stable perovskite solar cells. In particular, ALD will emerge for the production of tandem as well as flexible solar cells. This review contains the following recent research topics; underlying charge transport layers onto transparent conducting oxides (TCO), interfacial layers, overlying electron transport layers (ETLs), and encapsulation techniques utilized by ALD. Several extended understandings by recent studies and challenges toward further enhancing the efficiency and stability will be addressed.
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http://dx.doi.org/10.1039/c8cc09578gDOI Listing
February 2019

Aligned Heterointerface-Induced 1T-MoS Monolayer with Near-Ideal Gibbs Free for Stable Hydrogen Evolution Reaction.

Small 2019 Feb 30;15(8):e1804903. Epub 2019 Jan 30.

Department of Chemical and Biomolecular Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 120-749, Republic of Korea.

1T-phase molybdenum disulfide (1T-MoS ) exhibits superior hydrogen evolution reaction (HER) over 2H-phase MoS (2H-MoS ). However, its thermodynamic instability is the main drawback impeding its practical application. In this work, a stable 1T-MoS monolayer formed at edge-aligned 2H-MoS and a reduced graphene oxide heterointerface (EA-2H/1T/RGO) using a precursor-in-solvent synthesis strategy are reported. Theoretical prediction indicates that the edge-aligned layer stacking can induce heterointerfacial charge transfer, which results in a phase transition of the interfacial monolayer from 2H to 1T that realizes thermodynamic stability based on the adhesion energy between MoS and graphene. As an electrocatalyst for HER, EA-2H/1T/RGO displays an onset potential of -103 mV versus RHE, a Tafel slope of 46 mV dec and 10 h stability in acidic electrolyte. The unexpected activity of EA-2H/1T/RGO beyond 1T-MoS is due to an inherent defect caused by the gliding of S atoms during the phase transition from 2H to 1T, leading the Gibbs free energy of hydrogen adsorption (ΔG ) to decrease from 0.13 to 0.07 eV, which is closest to the ideal value (0.06 eV) of 2H-MoS . The presented work provides fundamental insights into the impressive electrochemical properties of HER and opens new avenues for phase transitions at 2D/2D hybrid interfaces.
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http://dx.doi.org/10.1002/smll.201804903DOI Listing
February 2019

Atomic layer deposition of a SnO electron-transporting layer for planar perovskite solar cells with a power conversion efficiency of 18.3.

Chem Commun (Camb) 2019 Feb;55(17):2433-2436

Department of Energy Science, Sungkyunkwan University, Suwon 440-746, Republic of Korea.

High-efficiency planar type perovskite solar cells were fabricated by atomic layer deposition (ALD) of SnO2 and subsequent annealing at 180 °C. As-dep. SnO2 layers prepared by post-annealing at 180 and 300 °C, respectively, were used as electron transporting layers (ETLs). ALD-TiO2 layers were also prepared by post annealing at 400 °C, and the thicknesses of all ETLs were around 12 nm. PL quenching, optical band gap measurement, UPS, and conductive AFM results show that SnO2 can more appropriately be used as an ETL compared to TiO2.
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http://dx.doi.org/10.1039/c8cc09557dDOI Listing
February 2019

Anti-acne properties of hydrophobic fraction of red ginseng (Panax ginseng C.A. Meyer) and its active components.

Phytother Res 2019 Mar 3;33(3):584-590. Epub 2018 Dec 3.

College of Pharmacy, Korea University, Sejong, Republic of Korea.

Acne is a chronic inflammatory disease of the skin that occurs when bacteria abnormally grow in hair follicles. The most common treatment is antibiotics, but they are limited due to antibiotic resistance. The purpose of this study was to identify the active ingredients of the antimicrobial effects of red ginseng (Panax ginseng C.A. Meyer), compare it to existing antibacterial substances, and determine its potential efficacy as a natural drug product. The hydrophobic fraction in red ginseng ethanol extract (RGEF) showed the same or better antimicrobial activity against Propionibacterium acnes than benzoyl peroxide or azelaic acid. In addition, the antimicrobial component derived from red ginseng selectively showed a high antimicrobial effect on P. acnes. Nuclear magnetic resonance spectroscopic analysis showed that the active antimicrobial substance in this fraction was panaxynol and panaxydol. Twenty subjects who had acne symptoms were treated with cream containing 3 mg/g of RGEF for 4 weeks. It was found that oxidized sebum contents and redness of the skin were reduced, and symptoms of the early to middle stage of acne were effectively improved. This study showed that red ginseng extract containing panaxynol and panaxydol can effectively control the symptoms of acne.
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http://dx.doi.org/10.1002/ptr.6243DOI Listing
March 2019