missForest with feature selection using binary particle swarm optimization improves the imputation accuracy of continuous data

Jin Heejin,Jung Surin,Won Sungho 한국유전학회 2022 Genes & Genomics Vol.44 No.6

Background: Missing data are a common problem in large-scale datasets and its appropriate handling is crucial for data analyses. Missingness can be categorized as (1) missing completely at random (MCAR), (2) missing at random (MAR), and (3) missing not at random (MNAR). Different missingness mechanisms require different imputation strategies. Multiple imputation, an approach for averaging outcomes across multiple imputed data, is more suitable than single imputation for dealing with various missing mechanisms. missForest, a nonparametric missing value imputation strategy using random forest, is one of the most prevalent multiple imputation methods for missing-data because it can be applied to mixed-type data and does not require distributional assumptions. However, a recent study found that missForest can produce biased results for non-normal data. In addition, missForest is computationally expensive. Objective: Therefore, we aimed to further develop the missForest algorithm by combining a binary particle swarm optimization (BPSO)-based feature-selection strategy. Methods: The BPSO is an evolutionary algorithm that is well known for global optimization and computational efficiency. By using the BPSO-based feature selection step prior to imputing missing values with missForest, the imputation accuracy for continuous variables could be increased by pruning redundant variables. Results: In this study, missForest with BPSO (BPSOmf) showed better imputation accuracy than missForest alone with respect to continuous variables by feature selection prior to the imputation step. Conclusions: BPSOmf is an appropriate and robust method when the imputation target data consist mainly of continuous variables.

Genome-Wide Association Study on Longitudinal Change in Fasting Plasma Glucose in Korean Population

Jin Heejin,곽수헌,윤지원,이상헌,박경수,Won Sungho,Cho Nam H. 대한당뇨병학회 2023 Diabetes and Metabolism Journal Vol.47 No.2

Background: Genome-wide association studies (GWAS) on type 2 diabetes mellitus (T2DM) have identified more than 400 distinct genetic loci associated with diabetes and nearly 120 loci for fasting plasma glucose (FPG) and fasting insulin level to date. However, genetic risk factors for the longitudinal deterioration of FPG have not been thoroughly evaluated. We aimed to identify genetic variants associated with longitudinal change of FPG over time.Methods: We used two prospective cohorts in Korean population, which included a total of 10,528 individuals without T2DM. GWAS of repeated measure of FPG using linear mixed model was performed to investigate the interaction of genetic variants and time, and meta-analysis was conducted. Genome-wide complex trait analysis was used for heritability calculation. In addition, expression quantitative trait loci (eQTL) analysis was performed using the Genotype-Tissue Expression project.Results: A small portion (4%) of the genome-wide single nucleotide polymorphism (SNP) interaction with time explained the total phenotypic variance of longitudinal change in FPG. A total of four known genetic variants of FPG were associated with repeated measure of FPG levels. One SNP (rs11187850) showed a genome-wide significant association for genetic interaction with time. The variant is an eQTL for NOC3 like DNA replication regulator (<i>NOC3L</i>) gene in pancreas and adipose tissue. Furthermore, <i>NOC3L</i> is also differentially expressed in pancreatic β-cells between subjects with or without T2DM. However, this variant was not associated with increased risk of T2DM nor elevated FPG level.Conclusion: We identified rs11187850, which is an eQTL of <i>NOC3L</i>, to be associated with longitudinal change of FPG in Korean population.

Fluorous-inorganic hybrid dielectric materials for solution-processed electronic devices

Kim, Heejin,Jo, Sang Ho,Jee, Joong-Hwi,Han, WooJe,Kim, Youngtae,Park, Hyung-Ho,Jin, Hyoung-Joon,Yoo, Byungwook,Lee, Jin-Kyun The Royal Society of Chemistry 2015 NEW JOURNAL OF CHEMISTRY Vol.39 No.2

<P>We report the synthesis and characterisation of fluorous-inorganic hybrid dielectric (FIHD) materials processable in highly fluorinated orthogonal solvents for printed electronic devices. FIHD materials were prepared successfully <I>via</I> ligand exchange reactions between organic ligands on the surfaces of nanomaterials and highly fluorinated carboxylic acids. When hafnium oxide (HfO<SUB>2</SUB>) or zirconium oxide (ZrO<SUB>2</SUB>) nanoparticles stabilized with trioctylphosphine oxide (TOPO) were treated with perfluoro-3,6,9-trioxatridecanoic acid in HFE-7500 at 130 °C, the modified surface characteristics of the nanoparticles resulted in excellent solubilities in the fluorous solvent. The dielectric constant of HfO<SUB>2</SUB> and ZrO<SUB>2</SUB> nanoparticles modified with fluorous acid was <I>ca.</I> 4.4 and 4.3 at 1 KHz, respectively, which is significantly higher than that of fluoropolymers. Top-gate organic thin film transistors (OTFTs) were fabricated using solution-processed organic semiconductors and HfO<SUB>2</SUB>-based FIHD materials. The hole mobilities of the OTFTs produced were as high as 0.08 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP> (<I>V</I><SUB>ds</SUB> = −40 V) and the on/off ratio reached 3.3 × 10<SUP>6</SUP> when 2,8-difluoro-5,11-bis(triethylsilylethynyl)anthradithiophene (diF-TESADT) was employed as the semiconductor layer. These device performances demonstrate that FIHD materials can be useful components for general printed electronic devices processed with soluble organic electronic materials.</P> <P>Graphic Abstract</P><P>Fluorous-inorganic hybrid dielectric (FIHD) materials in fluorous solvents can be deposited on top of organic semiconductor films by solution casting. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4nj01435a'> </P>

자동차 배기계 플랜지용 16~19 wt.% 페라이트 주조용 스테인리스강 개발

장희진(HeeJin Jang),범원진(Won-Jin Beom),박찬진(Chan-Jin Park) 한국표면공학회 2009 한국표면공학회지 Vol.42 No.2

We aimed to develop a Fe-(16~19)Cr-(0.1~0.6)Ti-(0.1~0.6)Nb stainless steel for automotive exhaust parts with h igh corrosion resistance. Th e alloys w ith h igh Cr content sh owed h igh resistance to general corrosion and also localized corrosion. The increase of Ti and Nb contents resulted in a linear increase in the general corrosion resistance, while the pitting potential was improved by addition of these elements up to about 0.4 wt.%. The low-carbon Fe-17Cr-0.4Ti-0.4Nb alloy annealed at 850oC and air-cooled was considered to be the optimum alloy for our purpose with the critical anodic current density of 247 ㎂/㎠ in 0.05 M H₂SO₄ solution and the pitting potential of 310 ㎷SCE in 0.2 M NaCl solution.

Efficient and Rapid Co-Fermentation of Mixed Sugars by Engineered Saccharomyces Cerevisiae

Suk-jin HA,Soo Rin KIM,Heejin KIM,Eun Joong OH,Myoung-Uoon JANG,Jonathan M. GALAZKA,Jamie H.D. CATE,Yong-Su JIN 한국생물공학회 2013 한국생물공학회 학술대회 Vol.2013 No.4

A monolithic and flexible fluoropolymer film microreactor for organic synthesis applications.

Kim, Jin-Oh,Kim, Heejin,Ko, Dong-Hyeon,Min, Kyoung-Ik,Im, Do Jin,Park, Soo-Young,Kim, Dong-Pyo Royal Society of Chemistry 2014 Lab on a chip Vol.14 No.21

<P>A photocurable and viscous fluoropolymer with chemical stability is a highly desirable material for fabrication of microchemical devices. Lack of a reliable fabrication method, however, limits actual applications for organic reactions. Herein, we report fabrication of a monolithic and flexible fluoropolymer film microreactor and its use as a new microfluidic platform. The fabrication involves facile soft lithography techniques that enable partial curing of thin laminates, which can be readily bonded by conformal contact without any external forces. We demonstrate fabrication of various functional channels (~300 μm thick) such as those embedded with either a herringbone micromixer pattern or a droplet generator. Organic reactions under strongly acidic and basic conditions can be carried out in this film microreactor even at elevated temperature with excellent reproducibility. In particular, the transparent film microreactor with good deformability could be wrapped around a light-emitting lamp for close contact with the light source for efficient photochemical reactions with visible light, which demonstrates easy integration with optical components for functional miniaturized systems.</P>

Indicator components analysis using LC-QTOF MPP profiling of the rind extract of Stauntonia hexapylla Fruit(green) according to the extraction solvent

Heejin Seol,Jiseon Lee,Jin-young Lee,So-Young Kang 한국분석과학회 2022 학술대회논문집 Vol.2022 No.11

Cerebrospinal fluid liquid biopsies for Mucopolysaccharidosis: absolute quantitation of glycans with high sensitivity using HILIC/MRM-MS

Heejin Jeong,Myung Jin Oh,Nari Seo,Hyun Joo An 한국당과학회 2022 한국당과학회 학술대회 Vol.2022 No.07

In recent years, liquid biopsy has been noted for its outstanding advantages over tissue biopsy including ease of sampling, effective monitoring, and longitudinal assessment of treatment dynamics. In particular, Cerebrospinal fluid(CSF), a body fluid that directly interacts with the extracellular fluid of the brain and central nervous system, is a representative body fluid used for liquid biopsy and is becoming a potential source for neurological study. Mucopolysaccharidosis is a fatal neurodegenerative lysosomal storage disease caused by lysosomal β-gal deficiency and of galactose-containing substrates accumulate in various tissues such as brain and liver. Therefore, continuous monitoring of changes in the expression of galactose substrates in the brain is important for the diagnosis and treatment of disease. However, the low protein content of the biofluid makes this difficult. Here, we developed a highly sensitive, absolute quantitation platform for N-glycans containing terminal galactose(A2G2/A2G2F) to determine mucopolysaccharidosis using liquid biopsy of mouse CSF within 2hours. N-glycans labeled with InstantPC were quantified using hydrophilic interaction chromatography(HILIC) coupled with multiple response monitoring(MRM)-MS. In particular, A2G2/A2G2F glycans are present in less than 5% even in very small amount of mouse CSF, but it is possible to quantify glycans in 300nL mouse CSF at the femtomole level. Indeed, we were able to achieve high reproducibility within 15% of CV in experimental/instrumental replicates in the concentration range of 0.1 to 500pg/μL with quantitative linearity. Our glycan quantification platform can be potentially applied for diagnosis and monitoring of patients for neurodegenerative diseases at trace amounts of CSF (about 5μL) in a much more convenient and non-invasive manner.

Radiation medicine infrastructure in north korea

Heejin Kim,Jung Young Kim,Kyo Chul Lee,Sang Moo Lim,Yong Jin Lee,Sung Chul Jung 대한방사성의약품학회 2018 Journal of radiopharmaceuticals and molecular prob Vol.4 No.2

Recently, South and North Korea summits agreed to implement the cooperation and promotion of medical healthcare at the third inter-Korean summit in Pyeongyang on September 18, 2018. Therefore, the South Korean government and its affiliated organizations have been looking for ways to establish a specific plan for support and exchanges in the field of healthcare and medical technology. In the background of the above new policy, radiation medicine technology can also contribute to the exchange in the field of healthcare and science & technology for the peaceful coexistence of one Korea. In this review, we analyzed and showed the status of healthcare and radiation medicine infrastructure in North Korea in order to further develop a plan to share the benefits of radiation medicine with North Korea in the exchange of healthcare and science & technology

Development of Tomato Mutant Population Using Micro-Tom Cultivar

Heejin Kim,Jae-In Chun,Won-ki Hong,Jin-Ho Kang 한국원예학회 2018 한국원예학회 학술발표요지 Vol.2018 No.10