• Bulletin of the Korean Chemical Society
• /
• v.15 no.1
• /
• pp.79-83
• /
• 1994

The organometallic chemical vapor deposition of single precursors, $[Me_2Al({\mu}-NHR)]_2\;(R=^iPr,\;^tBu)$, for alumininum nitride thin films has been investigated to evaluate their poroperties as potential precursors. In chemical vapor deposition processes the gas phase products scattered from a Ni(100) substrate were analyzed by mass spectrometry and the deposited films were characterized by X-ray photoelectron spectroscopy (XPS). The optimum temperatures for the formation of AlN films have been found to be between 700 K and 800 K. Carbon contamination of the films seems to be attributed mainly to the methyl groups bonded to the aluminum atoms. It is apparent that $^tBu$ group is better than $^iPr$ group as a substituent on the nitrogen atom of the single precursors for the AlN thin film formation.

• Biomolecules & Therapeutics
• /
• v.27 no.6
• /
• pp.540-552
• /
• 2019

To determine the chemopreventive potential of alyssin and iberin, the in vitro anticancer activities and molecular targets of isothiocyanates (ITCs) were measured and compared to sulforaphane in hepatocellular carcinoma cell HepG2. The SR-FTIR spectra observed a similar pattern vis-a-vis the biomolecular alteration amongst the ITCs-treated cells suggesting a similar mode of action. All of the ITCs in this study cause cancer cell death through both apoptosis and necrosis in concentration dependent manner ($20-80{\mu}M$). We found no interactions of any of the ITCs studied with DNA. Notwithstanding, all of the ITCs studied increased intracellular reactive oxygen species (ROS) and suppressed tubulin polymerization, which led to cell-cycle arrest in the S and $G_2/M$ phase. Alyssin possessed the most potent anticancer ability; possibly due to its ability to increase intracellular ROS rather than tubulin depolymerization. Nevertheless, the structural influence of alkyl chain length on anticancer capabilities of ITCs remains inconclusive. The results of this study indicate an optional, potent ITC (viz., alyssin) because of its underlying mechanisms against hepatic cancer. As a consequence, further selection and development of effective chemotherapeutic ITCs is recommended.

• Journal of Microbiology and Biotechnology
• /
• v.29 no.10
• /
• pp.1553-1560
• /
• 2019

In a previous study, the antimicrobial peptides extracted from Lactobacillus plantarum UTNGt2 of wild-type fruits of Theobroma grandiflorum (Amazon) were characterized. This study aimed to investigate the antimicrobial mechanisms of peptides in vitro and its protective effect on fresh tomatoes. The addition of partially purified Gt2 peptides to the E. coli suspension cells at the exponential ($OD_{605}=0.7$) growth phase resulted in a decrease with 1.67 (log10) order of magnitude compared to the control without peptide. A marginal event (< 1 log10 difference) was recorded against Salmonella, while no effect was observed when combined with EDTA, suggesting that the presence of a chelating agent interfered with the antimicrobial activity. The Gt2 peptides disrupted the membrane of E. coli, causing the release of ${\beta}$-galactosidase and leakage of DNA/RNA molecules followed by cell death, revealing a bacteriolytic mode of action. The tomatoes fruits coated with Gt2 peptides showed growth inhibition of the artificially inoculated Salmonella cocktail, demonstrating their preservative potential.

• Journal of Surface Science and Engineering
• /
• v.52 no.4
• /
• pp.187-193
• /
• 2019

Electroless Ni-P coatings are widely used in the chemical, mechanical, and electronic industries because of their excellent wear and abrasion resistance. In this study, the effect of $TiO_2$ particles of composite coating was investigated. To improve the corrosion resistance, electroless $Ni-P-TiO_2$composite coating was studied by varying the $TiO_2$ content. The morphology and phase structure of $Ni-P-TiO_2$ composite coatings were analyzed by scanning electron microscopy(SEM), X-ray diffractometry(XRD) and X-ray photoelectron spectroscopy(XPS). The result showed that $Ni-P-TiO_2$composite coating is composed of Ni, P, Ti and O. It exhibits an amorphous structure, high hardness and good corrosion resistance to the substrate. $Ni-P-TiO_2$ composite coatings have higher open circuit potential than that of the substrate, which obtained at $TiO_2$ content of 5.0 g/L optimal integrated properties.

• Journal of Magnetics
• /
• v.20 no.1
• /
• pp.11-20
• /
• 2015

In this work, Monte Carlo simulation was employed to model the stretchable Ising monolayer film to investigate the effect of the spatial distance variation among magnetic atoms on magnetic behavior of the film. The exchange interaction was considered as functions of initial interatomic distance and the stretched distance (or the strain). Following Bethe-Slater picture, the magnetic exchange interaction took the Lennard-Jones potential-like function. Monte Carlo simulations via the Wolff and Metropolis algorithms were used to update the spin systems, where equilibrium and dynamic magnetic profiles were collected. From the results, the strain was found to have strong influences on magnetic behavior, especially the critical behavior. Specifically, the phase transition point was found to either increase or decrease depending on how the exchange interaction shifts (i.e. towards or away from the maximum value). In addition, empirical functions which predict how the critical temperatures scale with initial interatomic distance and the strain were proposed, which provides qualitatively view how to fine tune the magnetic critical point in monolayer film using the substrate modification induced strain.

• Journal of Breast Disease
• /
• v.6 no.2
• /
• pp.39-45
• /
• 2018

Purpose: Dieckol, a phlorotannin compound isolated from Ecklonia cava, has been reported to have antioxidant, antiviral, anti-inflammatory, and anticancer properties. The purpose of this study was to investigate its anticancer effects on human breast cancer cell lines. Methods: In this study, the viability of two human breast cancer cell lines SK-BR-3 and MCF-7 was investigated after dieckol treatment using a WST-1 assay. Apoptosis and cell cycle distribution were assayed via Annexin V-fluorescein isothiocyanate and propidium iodide staining followed by flow cytometric analysis. Immunoblotting analysis was also performed using Bax/Bcl-2 to determine whether the dieckol-induced apoptosis was mediated by the intrinsic apoptotic pathway. Results: In a dose dependent manner, dieckol reduced the number of viable cells and increased the number of apoptotic cells. The effect of dieckol on the cell cycle distribution was analyzed using flow cytometry. Dieckol treatment significantly increased the percentage of MCF-7 and SK-BR-3 in the G2/M phase. Immunoblot analysis revealed that 24 hours of dieckol exposure increased the Bax/Bcl-2 ratio. Conclusion: Dieckol induced cytotoxicity in MCF-7 and SK-BR-3 human breast cancer cells inducing apoptosis and cell cycle arrest. Therefore, it is suggested that dieckol may be a potential therapeutic agent for breast cancer.

• Journal of Powder Materials
• /
• v.26 no.4
• /
• pp.334-339
• /
• 2019

To meet the current demand in the fields of permanent magnets for achieving a high energy density, it is imperative to prepare nano-to-microscale rare-earth-based magnets with well-defined microstructures, controlled homogeneity, and magnetic characteristics via a bottom-up approach. Here, on the basis of a microstructural study and qualitative magnetic measurements, optimized reduction conditions for the preparation of nanostructured Sm-Co magnets are proposed, and the elucidation of the reduction-diffusion behavior in the binary phase system is clearly manifested. In addition, we have investigated the microstructural, crystallographic, and magnetic properties of the Sm-Co magnets prepared under different reduction conditions, that is, $H_2$ gas, calcium, and calcium hydride. This work provides a potential approach to prepare high-quality Sm-Co-based nanofibers, and moreover, it can be extended to the experimental design of other magnetic alloys.

• Atmosphere
• /
• v.29 no.2
• /
• pp.219-226
• /
• 2019

Generally, the weather forecast system has been run using prescribed ocean condition. As it is widely known that coupling between atmosphere and ocean process produces consistent initial condition at all-time scales to improve forecast skill, there are many trials on the application of data assimilation of coupled model. In this study, we implemented a weakly coupled data assimilation (short for WCDA) system in global NWP model with low horizontal resolution for coupled forecast with uncoupled initialization, following WCDA system at the Met Office. The experiment is carried out for a typhoon evolution forecast in 2017. Air-sea exchange process provides SST cooling and gives a substantial impact on tendency of central pressure changes in the decaying phase of the typhoon, except the underestimated central pressure. Coupled data assimilation is a challenging new area, requiring further work, but it would offer the potential for improving air-sea feedback process on NWP timescales and finally contributing forecast accuracy.

• Journal of Electrochemical Science and Technology
• /
• v.9 no.4
• /
• pp.308-319
• /
• 2018

Single step electrodeposition of $Cu_2ZnSnS_4$ (CZTS) for solar cell applications was studied using an aqueous thiocyanate based electrolyte. The sodium thiocyanate complexing agent was found to decrease the difference in the deposition potential of the elements. X-ray diffraction analysis of the samples indicates the formation of kesterite phase CZTS. UV-vis studies reveal the band gap of the deposits to be in the range of 1.2 - 1.5 eV. The thickness of the deposit was found to decrease with increase in pH of the electrolyte. Nearly stoichiometric composition was obtained for CZTS films coated at pH 2 and 2.5. I-V characterization of the film with indium tin oxide (ITO) substrate in the presence and the absence of light source indicate that the resistance decrease significantly in the presence of light indicating suitability of the deposits for solar cell applications. Results of electrochemical impedance spectroscopic studies reveal that the cathodic process for sulfur reduction is the slowest among all the elements.

• Food Engineering Progress
• /
• v.21 no.1
• /
• pp.36-41
• /
• 2017

The release profiles of nisin from nisin-incorporating gel foods and the antimicrobial activities of the gels on the growth of Brochothrix thermosphacta in an aqueous system containing the gels have been investigated. A linear regression model was applied to determine the diffusion coefficient (D) for the diffusion of nisin in the gel. The antimicrobial activities of nisin released from 1, 2 and 3% (w/v) agar gels on the growth of B. thermosphacta in a broth medium with and without nisin were investigated. The D decreased from $1.2{\times}10^{-2}$ to $8.2{\times}10^{-3}$ and $6.4{\times}10^{-3}cm^2/s$ as the agar concentration in the gel increased from 1 to 2 and 3% (w/v), demonstrating the diffusion rate in the gels can be controlled by the agar concentration in gel. The agar gel incorporating nisin inhibited the B. thermosphacta growth in the broth medium by prolonging the lag phase. The growth inhibition was enhanced by the addition of nisin in the medium. The results of this study exhibited that the gel food is a feasible nisin delivery system with a controlled release achieved by the adjustment of agar concentration in the system, demonstrating the potential of nisin-incorporating gel for preserving particulate-containing drinks.