Ni-CNT nanocomposites were synthesized via the electrical explosion of wire (EEW) in acetone and deionized (DI) water liquid conditions with different CNT compositions. The change in the shape and properties of the Ni-CNT nanopowders were determined based on the type of fluids and CNT compositions. In every case, the Ni nanopowder had a spherical shape and the CNT powder had a tube shape. However, the Ni-CNT nanopowders obtained in DI water exhibited irregular shapes due to the oxidation of Ni. Phase analysis also revealed the existence of nickel oxide when using DI water, as well as some unknown peaks with acetone, which may form due to the metastable phase of Ni. Magnetic properties were investigated using a Vibrating Sample Magnetometer (VSM) for all cases. Nanopowders prepared in DI water conditions had better magnetic properties than those in acetone, as evidenced by the simultaneous formation of super paramagnetic NiO peaks and ferromagnetic Ni peaks. The DI water (Ni:CNT = 1:0.3) sample revealed better magnetic results than the DI water (Ni-CNT = 1:0.5) because it had less CNT contents.

In this study, we evaluated the effects of acid leaching on the properties of Cr powder synthesized using self-propagating high-temperature synthesis (SHS). Cr powder was synthesized from a mixture of Cr2O3 and magnesium (Mg) powders using the SHS Process, and the byproducts after the reaction were removed using acid leaching. The properties of the recovered Cr powder were analyzed via X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), particle size analysis (PSA), and oxygen content analysis. The results show that perfect selective leaching of Cr is challenging because of various factors such as incomplete reaction, reaction kinetics, the presence of impurities, and incompatibility between the acid and metal mixture. Therefore, this study provides essential information on the properties under acidic conditions during the production of high-quality Cr powder using a self-propagating high-temperature synthesis method.

항균력과 보습력을 동시에 가지고 있는 화장품용 첨가제인 1, 2-octanediol (OD)의 피부 문제점을 개선하기 위하여 galactoside 유도체인 1, 2-octanediol galactoside (OD-gal)를 대장균 β -galactosidase (β-gal)을 이용하여 합성하였다. 이 때, β-gal은 4.5 U/ml, OD 농도는 150 mM, pH 는 7.0, 그리고, 온도는 37℃가 OD로부터 OD-gal을 합성하는 최적 조건이었다. 이 조건에 24 시간 동 안 150 mM의 OD로부터 약 55.9 mM의 OD-gal이 합성되었고, 이 때, conversion 수율(mole 기준)은 약 37.2% 였다. 또한, 9 ml의 반응액에서 67.4 mg의 순수한 OD-gal을 정제할 수 있었으며, 반응액에 들어 있는 OD에서부터 정제를 포함하는 전체 합성수율은 weight 기준으로는 약 34.1% 이고, mole 기 준으로는 약 16.2% 정도였다. 이러한 연구결과는 보다 안전한 화장품용 첨가제로서 OD-gal의 산업화 에 기초자료로서 도움을 줄 것으로 생각된다.

Phenylethanol (PhE)에서 야기되는 피부 부작용 문제를 극복하기 위한 대안으로 phenylethanol galactoside (PhE-gal)에 대하여 연구하였다. 그 중에서도 대장균 효소 β-galalactosidase (β-gal)을 이용하여 PhE로부터 PhE-gal를 합성하는 반응의 최적 조건에 대하여 조사하였다. 그리고, 용매 분획연구를 수행하여 PhE-gal의 특성도 조사하였다. 반응조건 중에서 반응액의 β-gal 농도, PhE 농도, 반응액의 pH, 그리고 온도에 대하여 조사한 결과, 최적 β-gal의 농도는 0.45 U/ml, 최적 반응물 PhE의 농도는 1.0%, 최적 반응액의 pH는 8.0, 최적 반응온도는 40℃ 였다. 그리고, 최적 반응조건에서 48 시간까지의 반응을 관찰하였는데, 약 81.9 mM의 PhE로부터 약 47.4 mM의 PhE-gal이 합성되었고, PhE로부터 PhE-gal로의 전환수율은 약 57.9% 정도였다. 또한, PhE와 PhE-gal이 포함된 반응물을 용매 EA와 MC로 분획한 결과, 물 층으로 대부분의 PhE-gal이 분획 되었고, 용매 층으로는 PhE가 분획 되었다. 그러나, 물 층으로의 PhE-gal의 분획이 용매 MC를 사용할 때, 더 분명하고 명확하게 나타났으며, 용매 EA를 이용한 분획에서는 명확히 물 층으로 PhE-gal이 분획 되지 않았다. 앞으로, PhE-gal을 화장품에 사용할 수 있는 첨가물(방부제)로 개발하기 위한 후속연구를 계속 진행할 예정이다.

Zinc selenide (ZnSe) nanoparticles were synthesized in aqueous solution using glutathione (GSH) as a ligand. The influence of the ligand content, reaction temperature, and hydroxyl ion concentration (pH) on the fabrication of the ZnSe particles was investigated. The optical properties of the synthesized ZnSe particles were characterized using various analytical techniques. The nanoparticles absorbed UV-vis light in the range of 350-400 nm, which is shorter than the absorption wavelength of bulk ZnSe particles (460 nm). The lowest ligand concentration for achieving good light absorption and emission properties was 0.6 mmol. The reaction temperature had an impact on the emission properties; photoluminescence spectroscopic analysis showed that the photo-discharge characteristics were greatly enhanced at high temperatures. These discharge characteristics were also affected by the hydroxyl ion concentration in solution; at pH 13, sound emission characteristics were observed, even at a low temperature of 25oC. The manufactured nanoparticles showed excellent light absorption and emission properties, suggesting the possibility of fabricating ZnSe QDs in aqueous solutions at low temperatures.

In this research, a precipitation method was used to synthesize β-Ga2O3 powders with various particle morphologies and sizes under varying precipitation conditions, such as gallium nitrate concentration, pH, and aging temperature, using ammonium hydroxide and ammonium carbonate as precipitants. The obtained powders were characterized in detail by XRD, SEM, FT-IR, and TG-DSC. From the TG-DSC result, GaOOH phase was transformed to β-Ga2O3 at around 742˚C, and weight loss percent was about 14 % when NH4OH was used as a precipitant. Also, β-Ga2O3 formed at 749˚C and weight loss percent was about 15 % when (NH)2CO3 was used as a precipitant. XRD results showed that the obtained Ga2O3 had pure monoclinic phase in both cases. When (NH)2CO3 was used as a precipitant, the particle shape changed and became irregular. The range of particle size was about 500nm-4μm based on various concentrations of gallium nitrate solution with NH4OH. The particle size was increased from 1-2μm to 3-4μm and particle shape was changed from spherical to bar type by increasing aging temperature over 80˚C.

Multi shell graphite coated Ag nano particles with core/shell structure were successfully synthesized by pulsed wire evaporation (PWE) method. Ar and (10 vol.%) gases were mixed in chamber, which played a role of carrier gas and reaction gas, respectively. Graphite layers on the surface of silver nano particles were coated indiscretely. However, the graphite layers are detached, when the particles are heated up to in the air atmosphere. In contrast, the graphite coated layer was stable under Ar and atmosphere, though the core/shell structured particles were heated up to . The presence of graphite coated layer prevent agglomeration of nanoparticles during heat treatment. The dispersion stability of the carbon coated Ag nanoparticles was higher than those of pure Ag nanoparticles.