• Applied Chemistry for Engineering
• /
• v.27 no.2
• /
• pp.115-122
• /
• 2016

Melanin is a common name used for a certain type of natural dark pigments existing in living organisms, particularly in human hair, eyes, and skin. The unique free radical scavenging effect of melanine could help protecting cells and tissues from harmful UV light. While their exact molecular structures in nature are not still well defined, their multifunctional properties including electrical and ionic conductivities, antioxidation, wet adhesion, and metal ion chelation, are highlighted for the potential applications in bioorganic electronics including biomedical sensors and devices. In this mini-review, we will discuss sources, synthesis methods, structures and multifunctional properties of melanin materials in addition to current research directions on a wide range of applications.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.5 no.5
• /
• pp.462-465
• /
• 2004

After 6 month of using, cracking of gas exhaustion bag cage of Type 304 stainless steel wire for Al melting reverberatory furnace was founded in welds. Analysis of crack causes in the wire were tested by electrochemical method, SEM images of structure and analysis of composition. Resulted from the test, it could be observed that cracks in the welds were a accelerated by formed polythionic acid on surface of bag cage in sensitized region of HAZ, tensile stress and using environment.

• Resources Recycling
• /
• v.15 no.4 s.72
• /
• pp.60-63
• /
• 2006

Waste aluminum dross was leached with sulfuric acid to prepare alum used for water treatment product. The remained metallic aluminum in the waste aluminum dross was extracted into the solution to make aluminum sulfate solution. The solution could be used as alum for water treatment product after adjusting the required alumina concentration and the basicity. Comparing to the conventional method for alum using aluminum hydroxide, material cost could be saved in this method. Also, there is an additional merit in view of recycling of the waste aluminum dross by reducing the amount of waste dross to be landfilled.

• Journal of Environmental Health Sciences
• /
• v.45 no.5
• /
• pp.520-528
• /
• 2019

Objectives: This study assessed the cytotoxicity of the metallic mordant cupric acetate (CA) and the protective effect of Albizzia julibrissin (AJ) leaf extract on CA-induced cytotoxicity in NIH3T3 fibroblasts. Methods: For this study, cell viability and antioxidative effects such as the inhibitory activity of lipid peroxidation (LP) and superoxide anion-radical (SAR) scavenging activity were assessed. Results: CA significantly decreased cell viability in a dose-dependent manner, and the $XTT_{50}$ value was measured as $55.0{\mu}M$ of CA. The cytotoxicity of CA was determined as highly toxic by Borenfreund and Puerner's toxic criteria. The catalase antioxidant significantly increased cell viability diminished by CA-induced cytotoxicity in these cultures. Regarding the protective effect of AJ leaf extract on CA-induced cytotoxicity, AJ leaf extract remarkably increased the SAR scavenging ability and the inhibitory ability of LP. From these findings, it is suggested that oxidative stress is involved in the cytotoxicity of CA, and AJ leaf extract effectively protected CA-induced cytotoxicity via antioxidative effects. Conclusions: Natural resources like AJ leaf extract may be a putative therapeutic agent for treatment or alleviation of the toxicity induced by CA metallic mordant.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2012.05a
• /
• pp.424-428
• /
• 2012

Air-breathing Propulsion System is one of the promising propulsion systems because of low cost, easy storage, compactness and simplicity. A study of gas generator propellant for air-breathing propulsion system was performed in this paper. Amorphous Boron Powder was applied in propellant with various kinds of additives to determine combustion characteristics. And boron beads were made to apply them to the propellant. Combustion characteristics of propellant using amorphous boron powder and boron beads was compared.

• Journal of the Korean Electrochemical Society
• /
• v.22 no.3
• /
• pp.104-111
• /
• 2019

Metal halide perovskite materials are considered as promising semiconducting materials for next-generation solar cells due to their unique electrical and optical properties. Intensive progress in perovskite solar cell yielded a certified power conversion efficiency over 24%. However, most of highly efficient perovskite solar cells required Pb-based perovskite materials, which is a critical obstacle for their commercialization, and development of Pb-free perovskite materials is one of recent urgent issues in this field. In this paper, we will introduce recent research progress on Pb-free perovskite solar cells.

• Membrane Journal
• /
• v.29 no.3
• /
• pp.123-129
• /
• 2019

Environmental pollution caused by the presence of heavy metal ion from growing industrialization or from leaching is increasing area of concern. There are several area of water purifications but among them adsorption on the functionalized polymer fibers is efficient and cost-effective method. Polyacrylonitrile (PAN) is exciting polymer due to the presence of excessive functional group which can be easily transformed for metal ion adsorption. PAN can be easily electrospun to prepare nanofiber that have higher surface area leading to better metal ion removal. Composite PAN fiber is yet another type of polymer covered in this review for waste water treatment.

• Applied Chemistry for Engineering
• /
• v.30 no.1
• /
• pp.11-16
• /
• 2019

Ni-benzene-1,3,5-tricarboxylic acid based metal organic frameworks were successfully synthesized by hydrothermal method and thermally treated at various temperature. The electrochemical performance of composites was investigated using cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy. Among all prepared composites, the samples annealed at $250^{\circ}C$ showed the highest capacitance with a low resistance, and high cycle stability. It was possible to obtain the low electrical resistance and high electric conductivity of the electrode by improved microstructure and morphology after the thermal annealing at $250^{\circ}C$. The samples annealed at $250^{\circ}C$ also displayed the maximum specific capacitance with a value of $953Fg^{-1}$ at a current density of $0.66A/g^{-1}$ in 6 M KOH electrolyte. Moreover, a 86.4% of the initial specific capacitance of the composite was maintained after 3,000 times charge-discharge cycle tests. Based on these properties, it can be concluded that the composite could be applied as potential supercapacitor electrode materials.

• Applied Chemistry for Engineering
• /
• v.33 no.2
• /
• pp.216-221
• /
• 2022

Biocompatible polysaccharide coating technology can be a promising solution to overcome unexpected diseases caused by inflammatory reactions of metallic biomaterials (e.g., stent restenosis, etc.). However, due to their inherent hydrophilicity, it is difficult to maintain the coating layer for a long time in the physiological wet-environment. Herein, catechol functionalized hyaluronic acid was synthesized and introduced to the polymeric stent (polylactic acid) as the adhesive biocoating material. Surprisingly, even with the low degree of substitution of catechol (1.26%), a significant improvement in the underwater stability was observed, confirmed by capillary experiments and spectroscopic analysis. Our results may provide an insight into the positive role of catechol molecular adhesive group in the in-vivo stability of biocoating materials.

• Journal of Soil and Groundwater Environment
• /
• v.28 no.4
• /
• pp.1-5
• /
• 2023

In the fabrication of magnetic adsorbent by incorporating iron species on base materials with layered structure, there can be a potential loss of adsorption capacity from the penetration of dissolved iron species into the structure. This work newly synthesized a magnetic adsorbent by incorporating nano magnetite and glucose into layered metal sulfide via hydrothermal treatment, and tested the removal efficiencies of cesium ions (Cs⁺) by the adsorbents fabricated under different conditions (final temperature and glucose mass ratio). As a result, the optimal fabrication condition was found to be mass ratio of 1 (layered metal sulfide): 0.1 (nano magnetite): 0.4 (glucose) and final temperature of 160℃. As-prepared adsorbent possessed good adsorption ability of Cs⁺ (54.8 mg/g) without a significant loss of adsorption capacity from attaching glucose and nano magnetite onto the surface.