• Advances in nano research
• /
• v.7 no.4
• /
• pp.233-240
• /
• 2019

The present research work reports in-vitro anti-cancer activity of biologically synthesized ZnO nanoparticles (ZnO NPs) against human carcinoma cells viz SCC-40, SK-MEL-2 and SCC-29B using Sulforhodamine-B (SRB) Assay. ZnO NPs were synthesized by a unique and novel biological route using Temperature-gradient phenomenon where the extract of combination of Catharanthus roseus (L.) G. Don (C. roseus), Azadirachta indica (A. indica), Ficus religiosa (F. religiosa) and NaOH solution were used as synthesis medium. The morphology of the ZnO NPs was characterized by Transmission Electron Microscopy (TEM). TEM images reveal that particle size of the samples reduces from 76 nm to 53 nm with the increase in reaction temperature and 68 nm to 38 nm with the increase in molar concentration of NaOH respectively. XRD study confirms the presence of elements and reduction in crystallite size with increase in reaction temperature and NaOH concentration. The diffraction peaks show broadening and a slight shift towards lower Bragg angle ($2{\theta}$) which represents the reduction in crystallite size as well as presence of uniform strain. The FTIR spectra of the extract show transmittance peak fingerprint of Zn-O bond and presence of bioactive molecules These NPs exhibit inhibition greater than 50% for SCC-40, SK-MEL-2 and SCC-29B cell lines and more than 50% cell kill for SCC-29B cells at concentrations < $80{\mu}g/ml$. Nanoparticles with smallest size have shown better anti-cancer activity and peculiar cell-selectivity. The combination of extracts of these plants with ZnO NPs can be used in targeted drug delivery as an effective anti-cancer agent, a potential application in cancer treatment.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.43 no.3
• /
• pp.454-458
• /
• 2014

In this study, we examined the ionization rate and permeability of nanocalcium prepared from oyster shells with various particle sizes. Four particle sizes of the calcium samples were prepared by centrifugation according to their density disparity in alcoholic solution: NC (normal calcium), C-1 (supernatant of 1,000 rpm), C-2 (supernatant of 2,000 rpm), and C-3 (supernatant of 3,000 rpm). Particle sizes of NC, C-1, C-2, and C-3 were $2,280.3{\pm}64.3nm$, $521.3{\pm}83.3nm$, $313.9{\pm}29.5nm$, and $280.0{\pm}3.4nm$, respectively. C-3 showed a slight increase in ionization rate compared with the other calcium samples, but their differences were not significant. Dialysis membrane-employed analysis showed that nanocalcium permeability increased as its particle size smaller; 32% of C-3 nanocalcium was transported to the outside of the membrane, whereas C-1 showed a 25% transport rate. We determined the permeability of the nanocalciums by using rat intestinal sacs, in order to provide different intestinal environments depending on pH level. Nanocalcium generally showed a higher permeability at pH 7, which represents an ileum environments compared to the duodenum and jejunum environments at pH 4.2 and pH 6.2, respectively. However, C-3 calcium showed the highest permeability, followed by C-2, C-1 and NS calciums. This result shows that the size of calcium positively affected its permeability in the intestinal sac. Taken together, nano-sized calcium derived from discarded oyster shell shows improved permeability in intestinal environments.

• Journal of Technologic Dentistry
• /
• v.29 no.1
• /
• pp.121-131
• /
• 2007

A preparation process's conditions of aqueous sol which contains anatase-type nano titania particles with photocatalyic properties was established by using Yoldas process, so called, DCS(Destabilization of Colloidal Solution) process in this study. And crystal size change and phase transformation of titania particles in aqueous titania sol depending on reaction conditions was investigated by a light scattering method and XRD analysis of frozen dried powders, respectively. This sol with photo catalytic nano titania particles was used to the following hydrophilic hybrid coating film's fabrication and its properties was evaluated. Subsequently, for coating film using the above mentioned aqueous titania sol, non-aqueous titania sol was prepared without any chemical additives and its time stability according to aging time was investigate. By using the above mentioned aqueous titania sol and non-aqueous sol, a complex oxide coating sol for metal and ceramic substrate and a organic-inorganic hybrid coating sol for polymer substrate was prepared and it's hydrophilicity depending on UV irradiation conditions was evaluated. As a conclusions, the following results were obtained. (1)Aqueous titania sol The average particle size of titania in formed aqueous titania sol was distributed between 20$\sim$90nm range depending on reaction conditions. And the crystal phase of titania powders obtained by frozen drying method was changed from amorphous state to anatase and subsequently transformed to rutile crystal phase and it is attributed to concentration gradient in aqueous sol. (2)Non-aqueous titania sol Non-aqueous titania sol was prepared using methanol as a solvent and a little distilled water for hydrolysis and nitric acid as a catalyst were used. The obtained non-aqueous titania sol was stable at room temperature for 20 days. Additionally, non-aqueous titania sol with addition of chealating reagent such as acethylaceton and ethylene glycol prolonged the stability of sol by six months. (3)Complex sol and hybrid sol with super hydrophilicity The above mentioned aqueous titania sol as a main photocataylic component and non-aqueous titania sol as a binder for coating process was used to prepare a complex sol used for metal, ceramic and wood material substrate and also to prepare the organic-inorganic hybrid sol for polymer substrate such as polycarbonate and polyethylene, in which process APMS(3-Aminopropyltrimethoxysilane), GPTS(3-Glycidoxypropyl-trimethoxysilane) as a hydrophilic silane compound and HEMA(2-Hydroxyethyl methacrylate) as a forming network in hybrid coating film were used. The hybrid coating film such as prepared through this process showed a superhydrophilicity below 1$10^{\circ}$ depending on processing conditions and a pencil's hardness over 6 H.

• Journal of Environmental Impact Assessment
• /
• v.30 no.4
• /
• pp.247-257
• /
• 2021

In this work, Iron Nano-Particles Impregnated BioChar/bead (INPBC/bead) soil amendment was developed to increase biochar's reactivity to As in soil and preventing possible wind loss. Prior to preparation of INPBC/bead, INPBC was produced utilizing lignocellulosic biomass and Fe(III) solution in a hydrothermal method, followed by a calcination process. Then, the bead type amendment, INPBC/bead was produced by cross-linking reaction of alginate with INPBC. FT-IR, XRD, BET, and SEM-EDS analyses were utilized to characterize the as-synthesised materials. The particle size range of INPBC/bead was 1-4 mm, and different oxygen-containing functional groups and Fe3O4 crystalline phase were produced on the surface of INPBC/bead, according to the characterization results. The soil cultivation test was carried out in order to assess the stabilization performance of INPBC/bead utilizing As and Pb-contaminated soil obtained from an abandoned mining location in South Korea. After 4 weeks of culture, TCLP and SPLP extraction tests were performed to assess the stabilization efficacy of the amendment. The TCLP and SPLP findings revealed that raising the application ratio improved stabilizing efficiency. The As stabilization efficiency was determined to be 81.56 % based on SPLP test findings for a 5% in (w/w) INPBC/bead treatment, and the content of Pb in extracts was reduced to the limit of detection. According to the findings of this study, INPBC/bead that can maintain pH of origin soil and minimize wind loss might be a potential amendment for soil polluted with As and heavy metals.

• Journal of Powder Materials
• /
• v.9 no.6
• /
• pp.394-408
• /
• 2002

Nanostructured high strength metastable Al-, Mg- and Ti-based alloys containing different amorphous, quasicrystalline and nanocrystalline phases are synthesized by non-equilibrium processing techniques. Such alloys can be prepared by quenching from the melt or by powder metallurgy techniques. This paper focuses on one hand on mechanically alloyed and ball milled powders containing different volume fractions of amorphous or nano-(quasi)crystalline phases, consolidated bulk specimens and, on the other hand. on cast specimens containing different constituent phases with different length-scale. As one example. $Mg_{55}Y_{15}Cu_{30}$- based metallic glass matrix composites are produced by mechanical alloying of elemental powder mixtures containing up to 30 vol.% $Y_2O_3$ particles. The comparison with the particle-free metallic glass reveals that the nanosized second phase oxide particles do not significantly affect the glass-forming ability upon mechanical alloying despite some limited particle dissolution. A supercooled liquid region with an extension of about 50 K can be maintained in the presence of the oxides. The distinct viscosity decrease in the supercooled liquid regime allows to consolidate the powders into bulk samples by uniaxial hot pressing. The $Y_2O_3$ additions increase the mechanical strength of the composites compared to the $Mg_{55}Y_{15}Cu_{30}$ metallic glass. The second example deals with Al-Mn-Ce and Al-Cu-Fe composites with quasicrystalline particles as reinforcements, which are prepared by quenching from the melt and by powder metallurgy. $Al_{98-x}Mn_xCe_2$ (x =5,6,7) melt-spun ribbons containing a major quasicrystalline phase coexisting with an Al-matrix on a nanometer scale are pulverized by ball milling. The powders are consolidated by hot extrusion. Grain growth during consolidation causes the formation of a micrometer-scale microstructure. Mechanical alloying of $Al_{63}Cu_{25}Fe_{12}$ leads to single-phase quasicrystalline powders. which are blended with different volume fractions of pure Al-powder and hot extruded forming $Al_{100-x}$$(Al_{0.63}Cu_{0.25}Fe_{0.12})_x$ (x = 40,50,60,80) micrometer-scale composites. Compression test data reveal a high yield strength of ${\sigma}_y{\geq}$700 MPa and a ductility of ${\varepsilon}_{pl}{\geq}$5% for than the Al-Mn-Ce bulk samples. The strength level of the Al-Cu-Fe alloys is ${\sigma}_y{\leq}$550 MPa significantly lower. By the addition of different amounts of aluminum, the mechanical properties can be tuned to a wide range. Finally, a bulk metallic glass-forming Ti-Cu-Ni-Sn alloy with in situ formed composite microstructure prepared by both centrifugal and injection casting presents more than 6% plastic strain under compressive stress at room temperature. The in situ formed composite contains dendritic hcp Ti solid solution precipitates and a few $Ti_3Sn,\;{\beta}$-(Cu, Sn) grains dispersed in a glassy matrix. The composite micro- structure can avoid the development of the highly localized shear bands typical for the room temperature defor-mation of monolithic glasses. Instead, widely developed shear bands with evident protuberance are observed. resulting in significant yielding and homogeneous plastic deformation over the entire sample.

• Korean Journal of Materials Research
• /
• v.20 no.12
• /
• pp.669-675
• /
• 2010

One of the greatest challenges for our society is providing powerful electrochemical energy conversion and storage devices. Rechargeable lithium-ion batteries and fuel cells are among the most promising candidates in terms of energy and power density. As the starting material, $TiCl_4{\cdot}YCl_3$ solution and dispersing agent (HCP) were mixed and synthesized using ammonia as the precipitation agent, in order to prepare the nano size Y doped spherical $TiO_2$ precursor. Then, the $Li_4Ti_5O_{12}$ was synthesized using solid state reaction method through the stoichiometric mixture of Y doped spherical $TiO_2$ precursor and LiOH. The Ti mole increased the concentration of the spherical particle size due to the addition of HPC with a similar particle size distribution in a well in which $Li_4Ti_5O_{12}$ spherical particles could be obtained. The optimal synthesis conditions and the molar ratio of the Ti 0.05 mol reaction at $50^{\circ}C$ for 30 minutes and at $850^{\circ}C$ for 6 hours heat treatment time were optimized. $Li_4Ti_5O_{12}$ was prepared by the above conditions as a working electrode after generating the Coin cell; then, electrochemical properties were evaluated when the voltage range of 1.5V was flat, the initial capacity was 141 mAh/g, and cycle retention rate was 86%; also, redox reactions between 1.5 and 1.7V, which arose from the insertion and deintercalation of 0.005 mole of Y doping is not a case of doping because the C-rate characteristics were significantly better.

• Korean Journal of Food Science and Technology
• /
• v.41 no.6
• /
• pp.657-661
• /
• 2009

Liquid microparticulated seaweed calcium was manufactured via a wet grinding process. Thereafter, different forming agents such as cyclodextrin, gum arabic, and Na-caseinate were added to the liquid calcium, which was then spray-dried to investigate the quality of the powdered calcium treatments. The moisture contents of samples were approximately 2%. It was also determined that the different kinds of forming agents did not affect the spray drying efficiency. In addition, calcium solubility was the highest in a solution of pH 2. In buffer solution and vinegar, the powdered calcium made with gum arabic showed the highest solubility among the treatments. The calcium contents of all the powdered microparticulate seaweed calcium samples were about 28%, and calcium content was not affected by the forming agents. The spray-dried calcium powder made by spray drying with gum arabic had the highest water vapor uptake, whereas the seaweed calcium was stable in terms of water adsorption. The results of SEM observations indicated that a portion of the spray-dried calcium powders were in nano-scale after wet-grinding. Among the treatments, the use of saccharides as a forming agent resulted in the most uniform particle distribution after spray-drying.

• Journal of the Korean Applied Science and Technology
• /
• v.37 no.5
• /
• pp.1159-1170
• /
• 2020

In this study, to improve the stability of fermented squalene developed using microorganisms, Microsome-SQ20 was prepared, and its physical behavior, properties, and efficacy were studied. The appearance of Microsome-SQ20 was a transparent liquid, no smell, and had a specific smell. The color was a transparent liquid, and the specific gravity was 0.928 and the pH was 5.82 (20% solution), forming a nano-emulsion suitable for use in cosmetics. It was confirmed that the content of the main component of squalene was 20.05%, which was stably sealed. The particle size measured by 0.1% aqueous solution of Microsome-SQ20 was 134.8 nm to obtain a bluish emulsified phase. The antioxidant effects of F-SQ and MF-SQ by DPPH radicals were 80.72% and 81.5%, respectively, showing superior effects compared to L-ascorbic acid. The cell viability of squalene (SQ), fermented squalene (F-SQ) and microsome squalene (MF-SQ) was at 10 ppm, respectively, showing 121.2%, 150.3%, and 129.9% cell viability. It was found that SQ, F-SQ, and MF-SQ had an elastase inhibitory ability of 8.7%, 10.33% and 8.7% at 10 ppm, respectively. In addition, the inhibitory ability of MMP-1 was 1.55%, 41.44%, 31.79% at 10 ppm for SQ, F-SQ, and MF-SQ, respectively, indicating that F-SQ significantly reduced the MMP-1 expression.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.08a
• /
• pp.97-97
• /
• 2013

Recently, Cu2ZnSn(S,Se)4 (CZTSS), which is one of the In- and Ga- free absorber materials, has been attracted considerable attention as a new candidate for use as an absorber material in thin film solar cells. The CZTSS-based absorber material has outstanding characteristics such as band gap energy of 1.0 eV to 1.5 eV, high absorption coefficient on the order of 104 cm-1, and high theoretical conversion efficiency of 32.2% in thin film solar cells. Despite these promising characteristics, research into CZTSS based thin film solar cells is still incomprehensive and related reports are quite few compared to those for CIGS thin film solar cells, which show high efficiency of over 20%. I will briefly overview the recent technological development of CZTSS thin film solar cells and then introduce our research results mainly related to sputter based process. CZTSS thin film solar cells are prepared by sulfurization of stacked both metallic and sulfide precursors. Sulfurization process was performed in both furnace annealing system and rapid thermal processing system using S powder as well as 5% diluted H2S gas source at various annealing temperatures ranging from $520^{\circ}C$ to $580^{\circ}C$. Structural, optical, microstructural, and electrical properties of absorber layers were characterized using XRD, SEM, TEM, UV-Vis spectroscopy, Hall-measurement, TRPL, etc. The effects of processing parameters, such as composition ratio, sulfurization pressure, and sulfurization temperature on the properties of CZTSS absorber layers will be discussed in detail. CZTSS thin film solar cell fabricated using metallic precursors shows maximum cell efficiency of 6.9% with Jsc of 25.2 mA/cm2, Voc of 469 mV, and fill factor of 59.1% and CZTS thin film solar cell using sulfide precursors shows that of 4.5% with Jsc of 19.8 mA/cm2, Voc of 492 mV, and fill factor of 46.2%. In addition, other research activities in our lab related to the formation of CZTS absorber layers using solution based processes such as electro-deposition, chemical solution deposition, nano-particle formation will be introduced briefly.

• Journal of the Korean Ceramic Society
• /
• v.39 no.6
• /
• pp.550-557
• /
• 2002

TiO$_2$ particles coated on fly ash composites for use in photocatalyst were synthesized by the precipitation dropping method and heated at $700^{\circ}C$ for 2 h. The pH of reaction solution, the addition rate of NH$_4$HCO$_3$, the stirring speed, the reaction temperature and the concentration of TiC1$_4$ had a pronounced effect on the nature of precipitated TiO$_2$ particles on the surface off fly ash and the crystal structure of precipitated TiO$_2$ particles. At an addition rate of NH$_4$HCO$_3$; 1.0 ml/min, the pH of the reaction solution; 6, the stirring speed; 1,000 rpm and the reaction temperature; 8$0^{\circ}C$, about 10 nm of TiO$_2$ particle size and homogeneous precipitated layer on the surface of a fly ash was achieved. On the contrary, at an addition rate of NH$_4$HCO$_3$; 0.3,0.5 ml/min, the pH of the reaction solution; 2 and 11, the stirring speed; 300~500 rpm and the reaction temperature; lower than 5$0^{\circ}C$:, Inhomogeneous precipitated layer was developed on a fly ash. TiO$_2$ particles with anatase phase was formed as-dried precipitation at the low concentration of Tic14, the high addition rate of NH$_4$HCO$_3$ and the high reaction temperature, the crystalline fraction of anatase increased with raising heat-treatment temperature and rutile phase began to formation at 80$0^{\circ}C$. The crystal size of TiO$_2$ particles increased with raising the heat-treatment temperature, the crystal size was showed about 21 m at $700^{\circ}C$. Anatase type of TiO$_2$ coated on the fly ash heated at $700^{\circ}C$ for 2 h showed 1.25 g/cm$^3$of particle density, 82.8% of strength and 69.5 Lab of whiteness and can be used as a photocatalyst.