9 results on '"Taeyong Eom"'
Search Results
2. Comprehensive analysis of multi-class mycotoxins in twenty different species of functional and medicinal herbs using liquid chromatography–tandem mass spectrometry
- Author
-
Taeyong Eom, Jung-Hyun Kim, Junhee Kim, Seung Muk Hyun, Sang Beom Han, Shi Feng, Hyun-Deok Cho, Joon Hyuk Suh, and Yu Wang
- Subjects
Ochratoxin A ,Aflatoxin ,Chromatography ,Chemistry ,010401 analytical chemistry ,Extraction (chemistry) ,04 agricultural and veterinary sciences ,Mass spectrometry ,Quechers ,Orbitrap ,040401 food science ,01 natural sciences ,0104 chemical sciences ,law.invention ,chemistry.chemical_compound ,0404 agricultural biotechnology ,Liquid chromatography–mass spectrometry ,law ,Sample preparation ,Food Science ,Biotechnology - Abstract
Analysis of mycotoxins in functional and medicinal herbs is a challenge because herbs have complicated and diverse matrices from different parts of plants as well as different species. Here, we introduce a rapid and comprehensive liquid chromatography–tandem mass spectrometry method for the determination of multi-class mycotoxins (aflatoxin B1, B2, G1, G2, ochratoxin A, zearalenone, deoxynivalenol, fumonisin B1, B2, B3 and T-2 toxin) in twenty different species of herbs that are used for both food and medicinal purposes. Various sample preparation methods were compared and optimized to obtain satisfactory extraction of mycotoxins in different matrices. The extraction efficiency was found to vary from not only extraction methods but also matrix types, demonstrating the complexity of herbal matrix. On the basis of optimization results, immunoaffinity column was selected as an extraction method to cover all types of samples. QuEChERS was also employed as a supplementary method to support the immunoaffinity column method. The developed method was validated by assessing specificity, linearity, precision, recovery, limit of quantification and uncertainty, and applied in a hundred of real samples to monitor target mycotoxins. The monitoring results were further verified using accurate high resolution mass measurements by Orbitrap mass spectrometry. As far as we know, this is the first time the multi-class mycotoxins were determined in a broad range of functional and medicinal herb matrices, with high selectivity and sensitivity. In addition, the proposed method was proven to be more efficient and sensitive than other methods.
- Published
- 2019
3. Synthesis of novel volatile niobium precursors containing carboxamide for Nb2O5 thin films
- Author
-
Ji Hun Lee, Sunyoung Shin, Chang Gyoun Kim, Jeong Min Hwang, Na Yeon Kim, Taeyong Eom, Ji Yeon Ryu, Bo Keun Park, and Taek-Mo Chung
- Subjects
Thermogravimetric analysis ,Denticity ,010405 organic chemistry ,Chemistry ,medicine.drug_class ,Carboxamide ,Carbon-13 NMR ,010402 general chemistry ,01 natural sciences ,0104 chemical sciences ,Inorganic Chemistry ,chemistry.chemical_compound ,Pentagonal bipyramidal molecular geometry ,Polymer chemistry ,Pyridine ,Materials Chemistry ,medicine ,Salt metathesis reaction ,Physical and Theoretical Chemistry ,Single crystal - Abstract
A series of novel Nb(V) tBu-imido/N-alkoxy carboxamide complexes, NbCl2(NtBu)(pyridine)(edpa) (1), NbCl2(NtBu)(pyridine)(mdpa) (2), and Nb(NtBu)(mdpa)3 (3), were successfully synthesized by metathesis reaction between Nb(NtBu)Cl3(py)2 and several equivalents of Na(edpa) (edpaH = Nethoxy-2,2-dimethylpropanamide) and Na(mdpa) (mdpaH = N-methoxy-2,2-dimethylpropanamide). These complexes could potentially serve as precursors for Nb-containing thin films. Compounds 1–3 were characterized by FT-IR and 1H and 13C NMR spectroscopies, elemental analysis, and thermogravimetric analysis (TGA). Single crystal X-ray diffraction analysis suggested that complex 3 has a distorted pentagonal bipyramidal geometry around the central Nb atom, with three bidentate mdpa ligands and one tBu imido group saturating the coordination. TGA analysis revealed that the thermal characteristics of 3 were superior to those of 1 and 2. All prepared complexes were able to be distilled or sublimed and expected potential precursors for the fabrication of thin films.
- Published
- 2021
4. Atomic Layer Deposition of GeTe and Ge–Sb–Te Films Using HGeCl3, Sb(OC2H5)3, and {(CH3)3Si}2Te and Their Reaction Mechanisms
- Author
-
Cheol Seong Hwang, Chanyoung Yoo, Sergei A. Ivanov, Sang Gyun Kim, Taehong Gwon, Eui-Sang Park, Taeyong Eom, Moo-Sung Kim, Manchao Xiao, Sijung Yoo, and Iain Buchanan
- Subjects
Reaction mechanism ,Materials science ,General Chemical Engineering ,02 engineering and technology ,General Chemistry ,Substrate (electronics) ,GeSbTe ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Phase-change memory ,chemistry.chemical_compound ,Crystallography ,Atomic layer deposition ,chemistry ,Materials Chemistry ,Thin film ,0210 nano-technology ,Ternary operation ,Stoichiometry - Abstract
In this paper, a new atomic layer deposition (ALD) process for depositing binary GeTe and ternary Ge–Sb–Te thin films is reported, where HGeCl3 and ((CH3)3Si)2Te were used as Ge and Te precursors, respectively. The precursors reacted together to form the films at a low substrate temperature of 50–100 °C, without involving any additional reactive process gas. HCl elimination from the Ge precursor to form the divalent Ge intermediate, GeCl2, is proposed to explain the formation of 1:1 composition stoichiometric GeTe films. The GeTe films are promising for use in phase change memory applications. Ternary Ge–Sb–Te films were deposited by combining the GeTe ALD process with a previously developed ALD process for Sb2Te3 films, where Sb(OC2H5)3 and ((CH3)3Si)2Te were employed respectively as the Sb and Te precursors. However, the composition of the ternary GeSbTe films deviated slightly from the desired GeTe–Sb2Te3 pseudobinary composition suggesting that a certain unwanted reaction was involved between the prev...
- Published
- 2017
5. Multiclass mycotoxin analysis in edible oils using a simple solvent extraction method and liquid chromatography with tandem mass spectrometry
- Author
-
Hyun-Deok Cho, Jung-Hyun Kim, Moosung Kim, Jinyoung An, Mihee Park, Sang Beom Han, Sheen-Hee Kim, and Taeyong Eom
- Subjects
Electrospray ,Liquid Phase Microextraction ,Health, Toxicology and Mutagenesis ,Toxicology ,Mass spectrometry ,Tandem mass spectrometry ,Quechers ,01 natural sciences ,0404 agricultural biotechnology ,Tandem Mass Spectrometry ,Liquid chromatography–mass spectrometry ,Plant Oils ,Sample preparation ,Detection limit ,Chromatography ,Chemistry ,010401 analytical chemistry ,Selected reaction monitoring ,Public Health, Environmental and Occupational Health ,04 agricultural and veterinary sciences ,General Chemistry ,General Medicine ,Mycotoxins ,040401 food science ,0104 chemical sciences ,Solvents ,Plants, Edible ,Chromatography, Liquid ,Food Science - Abstract
A simple and rapid method for the simultaneous determination of 11 mycotoxins – aflatoxins B1, B2, G1 and G2; fumonisins B1, B2 and B3; ochratoxin A; zearalenone; deoxynivalenol; and T-2 toxin – in edible oils was established using liquid chromatography tandem mass spectrometry (LC-MS/MS). In this study, QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe), QuEChERS with dispersive liquid–liquid microextraction, and solvent extraction were examined for sample preparation. Among these methods, solvent extraction with a mixture of formic acid/acetonitrile (5/95, v/v) successfully extracted all target mycotoxins. Subsequently, a defatting process using n-hexane was employed to remove the fats present in the edible oil samples. Mass spectrometry was carried out using electrospray ionisation in polarity switching mode with multiple reaction monitoring. The developed LC-MS/MS method was validated by assessing the specificity, linearity, recovery, limit of quantification (LOQ), accuracy and precisio...
- Published
- 2017
6. Multicolor Changeable Optical Coating by Adopting Multiple Layers of Ultrathin Phase Change Material Film
- Author
-
Cheol Seong Hwang, Sijung Yoo, Taeyong Eom, Sang Gyun Kim, and Taehong Gwon
- Subjects
010302 applied physics ,Phase transition ,Materials science ,business.industry ,02 engineering and technology ,Optical storage ,021001 nanoscience & nanotechnology ,01 natural sciences ,Phase-change material ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Amorphous solid ,law.invention ,Optical coating ,Optics ,law ,Optical cavity ,0103 physical sciences ,Optoelectronics ,Electrical and Electronic Engineering ,Crystallization ,0210 nano-technology ,business ,Layer (electronics) ,Biotechnology - Abstract
The multilayered optical coating whose structure consists of optical cavity and multiple layers of ultrathin phase change material (PCM) film is presented. The color changing is enabled via transition between amorphous and crystalline phases of PCM, which is accompanied by high optical contrast. The phase transition of each PCM layer, separated by ultrathin oxide barrier, can be realized through various crystallization temperatures with respect to the different thickness of ultrathin (
- Published
- 2016
7. Aquilanols A and B, Macrocyclic Humulene-Type Sesquiterpenoids from the Agarwood of Aquilaria malaccensis
- Author
-
Taeyong Eom, Ki-Bong Oh, Tae Ryong Kim, Sung Won Kwon, Jeong Hill Park, Chi Thanh Ma, Sang Beom Han, Bo Wu, and Eunji Cho
- Subjects
Staphylococcus aureus ,Stereochemistry ,Molecular Conformation ,Pharmaceutical Science ,Crystallographic data ,Stereoisomerism ,Microbial Sensitivity Tests ,engineering.material ,010402 general chemistry ,Ring (chemistry) ,Crystallography, X-Ray ,01 natural sciences ,Analytical Chemistry ,chemistry.chemical_compound ,Drug Discovery ,Enterococcus faecalis ,Escherichia coli ,Organic chemistry ,Nuclear Magnetic Resonance, Biomolecular ,Aquilaria malaccensis ,Chromatography, High Pressure Liquid ,Pharmacology ,Hplc analysis ,Bicyclic molecule ,biology ,Humulene ,Molecular Structure ,010405 organic chemistry ,Chemistry ,Organic Chemistry ,Salmonella enterica ,Agarwood ,biology.organism_classification ,Wood ,0104 chemical sciences ,Monocyclic Sesquiterpenes ,Klebsiella pneumoniae ,Complementary and alternative medicine ,Laos ,Thymelaeaceae ,engineering ,Molecular Medicine ,Cholinesterase Inhibitors ,Sesquiterpenes ,Algorithms - Abstract
Four new and five known sesquiterpenoids were isolated from the agarwood of Aquilaria malaccensis. Aquilanols A and B (1 and 2) have an unprecedented macrocyclic humulene structure with a bicyclic 7/10 ring system. Compound 2 was obtained as a scalemic mixture that was resolved by HPLC analysis using a chiral column. Their structures were deduced based on spectroscopic data analysis, and the absolute configurations were unambiguously determined by X-ray crystallographic data and ECD spectroscopic analysis. A putative biosynthetic pathway of these sesquiterpenoids is proposed.
- Published
- 2017
8. Development of aqueous mobile phase using chaotrope for the chromatographic determination of melamine in infant formula
- Author
-
Yu Wang, Byeonghee Kim, Juhee Jung, Jung-Hyun Kim, Taeyong Eom, Sang Beom Han, Mihee Park, Joon Hyuk Suh, and Hyun-Deok Cho
- Subjects
Sodium hexafluorophosphate ,Analytical chemistry ,Ionic Liquids ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Analytical Chemistry ,chemistry.chemical_compound ,Column chromatography ,Phase (matter) ,Humans ,Chromatography, High Pressure Liquid ,Micelles ,Chromatography, Reverse-Phase ,Chromatography ,Aqueous solution ,Chemistry ,Triazines ,010401 analytical chemistry ,Organic Chemistry ,Infant ,Reproducibility of Results ,Green Chemistry Technology ,General Medicine ,Reversed-phase chromatography ,Infant Formula ,0104 chemical sciences ,Chaotropic agent ,Ionic liquid ,Solvents ,Melamine ,Food Analysis - Abstract
Direct analysis of melamine using reverse phase chromatography is a challenge because this compound's small size and strong polar nature leads to abnormal peak symmetry as well as poor retention. Here, we introduce a simple and reliable reverse phase liquid chromatographic method using sodium hexafluorophosphate to modify an acidic aqueous eluent, resulting in improved chromatographic behaviors of melamine in complex food matrices. Variables affecting the retention mechanism, including chaotrope type, concentration and stationary phase, were investigated. Under optimum conditions, melamine retention, separation efficiency, peak shape and reproducibility were significantly improved as compared to other methods that use ionic liquids or a micellar mobile phase. No interference affected melamine detection when infant formula was applied as the food matrix. Analytical reliability was demonstrated through estimation of validation parameters such as specificity, linearity, precision, accuracy and recovery. This method is suitable for routine analysis of melamine in infant formula. More noteworthy, this is the first time that an organic solvent-free mobile phase using chaotropic salt, meeting the concept of green chemistry, has been proposed.
- Published
- 2017
9. Effect of Electrode Material on the Crystallization of GeTe Grown by Atomic Layer Deposition for Phase Change Random Access Memory
- Author
-
In Hyuk Im, Chanyoung Yoo, Byung Joon Choi, Sung Yeon Ryu, Taeyong Eom, Yong Kim, Seok Choi, Seung Ik Oh, and Cheol Seong Hwang
- Subjects
Materials science ,phase change random access memory ,lcsh:Mechanical engineering and machinery ,Kinetics ,Nucleation ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Article ,law.invention ,Atomic layer deposition ,Thermal conductivity ,law ,lcsh:TJ1-1570 ,Electrical and Electronic Engineering ,Crystallization ,Composite material ,Mechanical Engineering ,electrode interfacial layer effect ,Johnson–Mehl–Avrami kinetics ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,chemistry ,Control and Systems Engineering ,Electrode ,crystallization behavior ,0210 nano-technology ,Tin ,Voltage - Abstract
The electrical switching behavior of the GeTe phase-changing material grown by atomic layer deposition is characterized for the phase change random access memory (PCRAM) application. Planar-type PCRAM devices are fabricated with a TiN or W bottom electrode (BE). The crystallization behavior is characterized by applying an electrical pulse train and analyzed by applying the Johnson&ndash, Mehl&ndash, Avrami kinetics model. The device with TiN BE shows a high Avrami coefficient (>, 4), meaning that continuous and multiple nucleations occur during crystallization (set switching). Meanwhile, the device with W BE shows a smaller Avrami coefficient (~3), representing retarded nucleation during the crystallization. In addition, larger voltage and power are necessary for crystallization in case of the device with W BE. It is believed that the thermal conductivity of the BE material affects the temperature distribution in the device, resulting in different crystallization kinetics and set switching behavior.
- Published
- 2019
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.