• Applied Chemistry for Engineering
• /
• v.30 no.5
• /
• pp.513-522
• /
• 2019

Catalysts based on organic compounds, transition metal and metal-organic frameworks (MOFs) have been applied to degrade or remove organophosphorus toxic compounds (OPs). During the last 20 years, various MOFs were designed and synthesized to suit application purposes. MOFs with $Zr_6$ based metal node and organic linker were widely used as catalysts due to their tunability for the pore size, porosity, surface area, Lewis acidic sites, and thermal stability. In this review, effect on catalytic efficiency between MOFs properties according to the structure, stability, particle size, number of connected-ligand, organic functional group, and so on will be discussed.

• Journal of Applied Biological Chemistry
• /
• v.64 no.2
• /
• pp.127-131
• /
• 2021

Perilla frutescens var. crispa (Pfc), a herb belonging to the mint family (Lamiaceae), has been used for medicinal and aromatic purposes. In the present study, we analyzed the variation in the chemical composition of essential oils (EOs) obtained from five different genotypes of Pfc collected from different regions. Based on principal component analysis (PCA) and hierarchical cluster analysis (HCA), we identified three groups: PA type containing perillaldehyde, PP type containing dillapiole, and 2-acetylfuran type. To assess the correlation between EO components and antimicrobial activities, we compared classification results generated by PCA and HCA based on antimicrobial activity values. The findings suggested that the major compounds obtained from EOs of Pfc are responsible for their antimicrobial activities. Chemotypes of Pfc plants are essentially qualitative traits that are important for breeders. The present findings provide potential information for breeding Pfc as an antimicrobial agent.

• Journal of the Korean Chemical Society
• /
• v.52 no.2
• /
• pp.140-147
• /
• 2008

.A new approach for a cloud point extraction-electrothermal atomic absorption spectrometric method was used for determining bismuth. The aqueous analyte was acidified with sulfuric acid (pH 3.0-3.5). Triton X-114 was added as a surfactant and natriumdiethyldithiocarbaminat (Na-DDTC) was used as a complexing agent. After phase separation at 50oC based on the cloud point separation of the mixture, the surfactant-rich phasen was diluted using tetrahydrofuran (THF). Twenty microliters (20 L) of the enriched solution and 10 l of 0.1% (w/v) Pd(NO3)2 as chemical modifier were dispersed into the graphite tube and the analyte determined by electrothermal atomic absorption spectrometry. After optimizing extraction conditions and instrumental parameters, a preconcentration factor of 195 was obtained for a sample of only 10 mL. The detection limit was 0.04 ng ml-1 and the analytical curve was linear for the concentration range of 0.04-0.70 ng mL-1. Relative standard deviations were <5%. The method was successfully applied for the extraction and determination of bismuth in water samples.

• Elastomers and Composites
• /
• v.36 no.1
• /
• pp.14-21
• /
• 2001

To increase the properties of EVA foam such as tensile strength, rebound resilience, and compression set, ethylene-1-butene copolymer (EtBC) was blended with EVA. After that crosslink characteristics of the blends and cell structures and mechanical properties of the foam were studied. As the amount of EtBC increased in EVA/EtBC blends, torque values of oscillating disc rheometer(ODR) increased and the foaming ratio decreased because the viscosity and crosslink density of EVA/EtBC blends increased. Foaming ratio and cell size of the foam increased by increasing the amount of foaming agent. When compared the mechanical properties of the foam which have same densities, tensile strength, rebound resilience, and compression set properties of the foam were improved by increasing the amount of EtBC in the EVA/EtBC blends.

• Membrane Journal
• /
• v.23 no.3
• /
• pp.245-250
• /
• 2013

In this study, the pervaporation separation characteristics were investigated for the iso-propyl alcohol (IPA)-water system using PDMS dense membranes. The ratio, 9:1 and 10:1, of the basic material based on RTV-655 and crosslinking agent were used to prepare dense membranes at the reaction temperatures, 40, 60, and $80^{\circ}C$. And these resulting membranes were characterized by pervaporation technique in terms of permeabilities and separation factors for the feed composition of IPA 85 wt% at the operating temperatures, 25, 35, 45, and $55^{\circ}C$. Typical results of permeabilities $148g/m^2{\cdot}hr$ at $55^{\circ}C$ for 9:1 membrane and the selectivity 17 at $55^{\circ}C$ for 10:1 membrane were obtained, respectively.

• Applied Chemistry for Engineering
• /
• v.29 no.2
• /
• pp.168-175
• /
• 2018

In order to investigate the effect of the chemical treatment of bamboo fiber on physical properties of polypropylene (PP)/bamboo fiber (BF) composites, silane coupling agents such as ${\gamma}$-aminopropyltriethoxysilane (APS), ${\gamma}$-glycidoxypropyl-trimethoxysilane (GPS) and ${\gamma}$-mercaptopropyltrimethoxysilane (MRPS) were applied to BF and alkaline treated BF. Morphological properties of the chemically treated BF were confirmed by optical microscope and SEM measurements, and chemical structure changes were confirmed by FT-IR and EDS. TGA results showed that the thermal stability of silane treated BF increased. Based on the analysis of a universal testing machine and an Izod impact test, the flexural and impact properties of PP/silane treated BF composites showed higher values than those of PP/BF composites. The enhancement of interfacial adhesion properties of the PP/BF composite was checked from SEM images of the fracture of specimens after the tensile test.

• Journal of Microbiology and Biotechnology
• /
• v.23 no.2
• /
• pp.161-166
• /
• 2013

At present, acetylcholinesterase (AChE) inhibitors are the first group of drugs to treat mild to moderate Alzheimer's disease (AD). Although beneficial in improving cognitive and behavioral symptoms, the effectiveness of AChE inhibitors has been questioned since they do not delay or prevent neurodegeneration in AD patients. Therefore, in the present study, in order to develop new and effective anti-AD agents from lichen products, both the AChE inhibitory and the neuroprotective effects were evaluated. The AChE inhibitory assay was performed based on Ellman's reaction, and the neuroprotective effect was evaluated by using the MTT method on injured PC12 cells. One AChE inhibitor ($IC_{50}$ = 27.1 ${\mu}g/ml$) was isolated by means of bioactivity-guided isolation from the extract of lichen-forming fungus Cladonia macilenta, which showed the most potent AChE inhibitory activity in previous screening experiment. It was then identified as biruloquinone by MS, and $^1H$- and $^{13}C$-NMR analyses. The inhibitory kinetic assay suggested that biruloquinone is a mixed-II inhibitor on AChE. Meanwhile, biruloquinone improved the viability of the $H_2O_2$- and ${\beta}$-amyloid-injured PC12 cells at 1 to 25 ${\mu}g/ml$. The protective effects are proposed to be related to the potent antioxidant activities of biruloquinone. These results imply that biruloquinone has the potential to be developed as a multifunctional anti- AD agent.

• Journal of the Korea Convergence Society
• /
• v.10 no.1
• /
• pp.285-290
• /
• 2019

AHR regulates the expression of xenobiotics metabolizing enzymes (XMEs) as a transcription fact upon binding of ligands that are mainly aryl hydrocarbons. The role of AHR in human physiology has been intensively investigated for the past decades, however our understanding on AHR yet to be elucidated largely due to the lack of proper chemical agents. It has been demonstrated that AHR correlates to pathogenesis for some diseases in recent studies suggesting that the study on the AHR may provide a valid therapeutic target. Classical antagonists in current use are reported to be partially agonistic whereas a pure antagonist is yet to be found. In this study, phenyldiazenylaniline has been designed based on the structure of two known AHR antagonist, Resveratrol and CH223191. The derivatives of phenyldiazenylaniline have been prepared and subjected to assessment as an AHR antagonist in order to optimize the AHR antagonistic activity of the designed structure by means of convergence study of organic synthesis and molecular biology.

• Journal of Adhesion and Interface
• /
• v.25 no.3
• /
• pp.75-81
• /
• 2024

This study analyzes the acid properties of zeolites synthesized through the use of surfactant-based structure-directing agents. To achieve this, zeolites possessing both micropores and mesopores were synthesized using surfactants containing multiple quaternary ammonium molecules. Those surfactants form mesoscale micelles to be mesopores after calcination, while the ammonium moieties direct zeolitic microporous structure. These hierarchical zeolites were then subjected to adsorption of different probe molecules, pyridine, and 2,6-di-tert-butylpyridine, followed by thermal desorption and analysis using FT-IR spectroscopy. The results reveal that unlike conventional zeolites consisting solely of micropores, the hierarchical zeolites exhibit strong acidity not only within the micropores but also on the external surface of the mesopores. This observation suggests the formation of strong acid sites attributed to the hierarchical porous structure induced by surfactant-type structure-directing agents. Consequently, these findings imply potential applications in various catalytic chemical reactions leveraging the surface acidity of zeolites.

• Applied Chemistry for Engineering
• /
• v.21 no.1
• /
• pp.63-70
• /
• 2010

Transition metal based spent catalysts (Ni-Mo and Co-Mo), which were scrapped from the petrochemical industry, were reused for the removal processes of volatile organic compounds (VOCs). Especially the optimum regeneration procedures were determined using the removal efficiency of VOCs. In this work, the spent Ni-Mo and spent Co-Mo catalysts were pretreated with different physic-chemical treatment procedure: 1) acid aqueous solution, 2) alkali solution, 3) chemical agent and 4) steam. The various characterization methods of spent and its regenerated catalysts were performed using nitrogen adsorption, X-ray diffraction (XRD) and scanning electron microscopy (SEM) equipped with an energy dispersive spectrometry (EDS). It was found that all spent catalysts were found to be potentially applicable catalysts for catalytic oxidation of benzene. The experimental results also indicated that among the employed physico-chemical pretreatment methods, the oxalic acid aqueous (0.1 N, $C_2H_2O_4$) pretreatment appeared to be the most efficient in increasing the catalytic activity, although the catalytic activity of spent Ni-Mo and spent Co-Mo catalysts in the oxidation of benzene were greatly dependent on the pretreatment conditions. The pretreated spent catalysts at optimum condition could be also applied for removing other aromatic compounds (Toluene/Xylene).