• Journal of Microbiology and Biotechnology
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• v.30 no.6
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• pp.920-925
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• 2020

In India, nanotechnology has been used in therapeutic applications for several millennia. One example of a traditional nanomedicine is Rajath Bhasma (also called calcined silver ash), which is used as an antimicrobial and for the treatment of various ailments and conditions such as memory loss, eye diseases, and dehydration. In this study, we aimed to characterize the physical composition and morphology of Rajath Bhasma and its suitability for use as a non-toxic antimicrobial agent. First, Rajath Bhasma was physically characterized via i) Fourier-transform infrared spectroscopy to analyze the surface functional groups, ii) scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy to observe the morphology and elemental composition, and iii) X-ray diffraction to determine the crystalline phases. Thereafter, functional characterization was performed through toxicity screening using zebrafish embryos and through antimicrobial activity assessment against gram-positive (Staphylococcus epidermidis) and gram-negative (Escherichia coli) bacteria. Rajath Bhasma was found to harbor alkene, hydroxyl, aldehyde, and amide functional groups originating from biological components on its surface. The main component of Rajath Bhasma is silver, with particle size of 170-210 nm, and existing in the form of spherical aggregates with pure crystalline silver structures. Furthermore, Rajath Bhasma did not exert toxic effects on zebrafish embryos at concentrations below 5 ㎍/ml and exhibited effective antimicrobial activity against both gram-positive and gram-negative bacteria. The present results indicate that Rajath Bhasma is a potentially effective antimicrobial agent without toxicity when used at concentrations below 5 ㎍/ml.

• Environmental Engineering Research
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• v.14 no.3
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• pp.164-169
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• 2009

A powder form of aluminum (hydr)oxides is not suitable in wastewater treatment/filtration systems because of low hydraulic conductivity and large sludge production. In this study, aluminum (hydr)oxide-coated sand (AOCS) was used to remove phosphate from aqueous solution. The properties of AOCS were analyzed using a scanning electron microscopy (SEM) combined with an energy dispersive X-ray spectrometer (EDS) and an X-ray diffractometer (XRD). Kinetic batch, equilibrium batch, and closed-loop column experiments were performed to examine the adsorption of phosphate to AOCS. The XRD pattern indicated that the powder form of aluminum (hydr)oxides coated on AOCS was similar to a low crystalline boehmite. Kinetic batch experiments demonstrated that P adsorption to AOCS reached equilibrium after 24 h of reaction time. The kinetic sorption data were described well by the pseudo second-order kinetic sorption model, which determined the amount of P adsorbed at equilibrium ($q_e$ = 0.118 mg/g) and the pseudo second-order velocity constant (k = 0.0036 g/mg/h) at initial P concentration of 25 mg/L. The equilibrium batch data were fitted well to the Freundlich isotherm model, which quantified the distribution coefficient ($K_F$ = 0.083 L/g), and the Freundlich constant (1/n = 0.339). The closed-loop column experiments showed that the phosphate removal percent decreased from 89.1 to 41.9% with increasing initial pH from 4.82 to 9.53. The adsorption capacity determined from the closed-loop experiment was 0.239 mg/g at initial pH 7.0, which is about two times greater than that ($q_e$ = 0.118 mg/g) from the kinetic batch experiment at the same condition.

• Journal of Conservation Science
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• v.36 no.1
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• pp.47-59
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• 2020

Scientific analysis was conducted to identify the paint pigments used in the Buseoksa Josadang murals. optical microscopy(OM), X-ray fluorescence(XRF), XRF mapping, scanning electron microscopy-energy dispersive X-ray spectroscopy(SEM-EDS), and Raman spectroscopy were performed to examine the pigments. The results confirmed that the Josadang murals consist of two paint layers wherein the pigments were distinct for most colors. It was estimated that celadonite, white clay, red ochre, cinnabar and minium, synthetic green pigment containing tin and zinc paratacamite, or botallackite were used in the upper layer. In addition, bone white, celadonite, red ochre, azurite, cinnabar or vermilion, and gold were identified in the lower layer. In addition, as Zn and Sn were detected in the green pigments extracted from the top layer of the paint, it is believed that Josadang murals were repainted over the original paint layer at some point after the 17th century. In addition, white pigments containing calcium phosphate were found in all the colors in the bottom layer, which is the original paint layer. These results are significant because this is the first time that white pigments are found in Korean traditional paintings. Additionally, the information revealed about the pigments in this study will serve as areference for the pigments used in the Goryeo period.

• Journal of Korean Society for Atmospheric Environment
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• v.9 no.3
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• pp.191-199
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• 1993

This paper describes the results of a systematic study to determine the characteristics of particle generated from various types of asbestos containing material(ACM) and manmade fiber material(MMFM) during operations of cutting and grinding in laboratory and workplace. Tests were conducted with a specially designed glove box which allowed complete sampling of the generated asbestos fibers. Specificially, air measurements were made during ACM and MMFM installation in building. All personal air samples collected were identified by polarized light microscopy(PLM), X-ray diffraction(XRD) and scanning electron microscope with energy dispersive X-ray analysis(SEM/EDXA). Also, the samples were counted by phase contrast microscope(PCM) in order to compare the results with the permissible exposure standard for workplace. Results indicate that the characterisitcs of fibers found in the roofing sheet, the ceiling and the wall insulation boards were identical to those of asbestos, while the characteristics of fibers found in the ceiling insulation board, the floor tile and the sprayed on insulation products in parking area were identical to those of asbestos, while the characteristics of fibers found in the ceiling insulation board, the floor tile and the sprayed on insulation products in parking area were identical to those of rock wool. The concentrations of airborne fibers from various building materials cut by a grinder for 5 minutes were in the ranges of 0.09 $\sim$ 1.71 fibers/cc(f/cc). The highest concentration(1.71f/cc) was found during grinding the wall insulation board which also contains rock wool. The airborne fiber concentrations generated by installing at workplace were ranged from 0.0009 to 0.029 f/cc. All asbestos fibers from the ceiling insulation board at workplace were less than 20$\mu$m in length and more than 20% of them had the average aspect ratio greater than 20. Therefore, for the purpose of decreasing asbestos and man-made fiber concentrations at the workplace, the ceiling and wall board should use strong binding material to increase the binding force with fiber. Also, the permissible exposure standard for workplace(2.0f/cc) in Korea should be constituted below the maximum avaiable concentration measured at glove box.

• Environmental Engineering Research
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• v.16 no.2
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• pp.81-90
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• 2011

Different weight percentages of Ag, Pt, and Au doped nano $TiO_2$ were synthesized using the acetic acid hydrolyzed sol-gel method. The crystallite phase, surface morphology combined with elemental composition and light absorption properties of the doped nano $TiO_2$ were comprehensively examined using X-ray diffraction (XRD), $N_2$ sorption analysis, transmission electron microscopic (TEM), energy dispersive X-ray, and DRS UV-vis analysis. The doping of noble metals stabilized the anatase phase, without conversion to rutile phase. The formation of gold nano particles in Au doped nano $TiO_2$ was confirmed from the XRD patterns for gold. The specific surface area was found to be in the range 50 to 85 $m^2$/g. TEM images confirmed the formation a hexagonal plate like morphology of nano $TiO_2$. The photocatalytic activity of doped nano $TiO_2$ was evaluated using 4-chlorophenol as the model pollutant. Au doped (0.5 wt %) nano $TiO_2$ was found to exhibit higher photocatalytic activity than the other noble metal doped nano $TiO_2$, pure nano $TiO_2$ and commercial $TiO_2$ (Degussa P-25). This enhanced photocatalytic activity was due to the cathodic influence of gold in suppressing the electron-hole recombination during the reaction.

• Journal of Conservation Science
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• v.35 no.5
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• pp.385-391
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• 2019

In order to examine the material characteristics of a black and white photograph of the Borobudur temple, in Indonesia, several analyses were conducted. A sample was taken from a black and white photograph; microscopy, Fourier transform-infrared spectroscopy, scanning electron microscopy/energy dispersive spectroscopy, X-ray diffraction, and X-ray fluorescence analyses showed that the black and white photograph was composed of four layers including a paper substrate, baryta, binder and surface layers. It was confirmed that the substrate was paper made of cellulose fiber from Cannabis sativa, the baryta layer was made of barium sulfate(BaSO₄) in powder form, the binder was an emulsion containing silver halide, and the surface protective layer was made of gelatin. Since photographs have different characteristics and require different preservation environments depending on the material of construction, it is necessary to study various black and white photographic material characteristics corresponding to each time period.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.5 no.2
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• pp.1-6
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• 2009

Nuclear power plants (NPP) using Alloy 600 (Ni 75wt%, Cr 15wt%, Fe 10wt%) as a heat exchanger tube of the steam generator (SG) have experienced various corrosion problems by ageing such as pitting, intergranular attack (IGA) and stress corrosion cracking (SCC). In spite of much effort to reduce the material degradations, SCC is still one of important problems to overcome. Especially lead is known to be one of the most deleterious species in the secondary system that cause SCC of the alloy. Even Alloy 690 (Ni 60wt%, Cr 30wt%, Fe 10wt%) as an alternative of Alloy 600 because of outstanding superiority to SCC is also susceptible to leaded environment. An oxide on SG tubing materials such as Alloy 600 and Alloy 690 is formed and modified expanding to complex sludge throughout hideout return (HOR) of various impurities including Pb. Oxide formation and breakdown is requisite for SCC initiation and propagation. Therefore it is expected that an oxide property such as a passivity of an oxide formed on steam generator tubing materials is deeply related to PbSCC and an inhibitor to hinder oxide modification by lead efficiently can be found. In the present work, the SCC susceptibility obtained by using a slow strain rate test (SSRT) in aqueous solutions with and without lead was discussed in view of the oxide property. The oxides formed on Alloy 600 and Alloy 690 in aqueous solutions with and without lead were examined by using a transmission electron microscopy (TEM), an energy dispersive x-ray spectroscopy (EDXS), an x-ray photoelectron spectroscopy (XPS) and an electrochemical impedance spectroscopy (EIS).

• Korean Journal of Materials Research
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• v.20 no.7
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• pp.345-350
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• 2010

For the present paper, we prepared MgO/MWCNT/$TiO_2$ photocatalyst by using multi-walled carbon nanotubes (MWCNTs) pre-oxidized by m-chlorperbenzoic acid (MCPBA) with magnesium acetate tetrahydrate $(Mg(CH_2COO)_2\cdot4H_2O)$ and titanium n-butoxide $(Ti\{OC(CH_3)_3\}_4)$ as magnesium and titanium precursors. The prepared photocatalyst was analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis. The decomposition of methylene blue (MB) solution was determined under irradiation of ultraviolet (UV) light. The XRD results show that the MgO/MWCNT/$TiO_2$ photocatalyst have cubic MgO structure and anatase $TiO_2$ structure. The porous structure and the $TiO_2$ agglomerate coated on the MgO/MWCNT composite can be observed in SEM images. The Mg, O, Ti and C elements can be also observed in MgO/MWCNT/$TiO_2$ photocatalyst from EDX results. The results of photodegradation of MB solution under UV light show that the concentration of MB solution decreased with an increase of UV irradiation time for all of the samples. Also, the MgO/MWCNT/$TiO_2$ photocatalyst has the best photocatalytic activity among these samples. It can be considered that the MgO/MWCNT/$TiO_2$ photocatalyst had a combined effect, the effect of MWCNT, which could absorb UV light to create photoinduced electrons $(e^-)$, and the electron trapping effect of MgO, which resulted in an increase of the photocatalytic activity of $TiO_2$.

• Korean Journal of Materials Research
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• v.24 no.4
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• pp.194-200
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• 2014

Metallic Cr film coatings of $1.2{\mu}m$ thickness were prepared by DC magnetron sputter deposition method on c-plane sapphire substrates. The thin Cr films were ammoniated during horizontal furnace thermal annealing for 10-240 min in $NH_3$ gas flow conditions between 400 and $900^{\circ}C$. After annealing, changes in the crystal phase and chemical constituents of the films were characterized using X-ray diffraction (XRD) and energy dispersive X-ray photoelectron spectroscopy (XPS) surface analysis. Nitridation of the metallic Cr films begins at $500^{\circ}C$ and with further increases in annealing temperature not only chromium nitrides ($Cr_2N$ and CrN) but also chromium oxide ($Cr_2O_3$) was detected. The oxygen in the films originated from contamination during the film formation. With further increase of temperature above $800^{\circ}C$, the nitrogen species were sufficiently supplied to the film's surface and transformed to the single-phase of CrN. However, the CrN phase was only available in a very small process window owing to the oxygen contamination during the sputter deposition. From the XPS analysis, the atomic concentration of oxygen in the as-deposited film was about 40 at% and decreased to the value of 15 at% with increase in annealing temperature up to $900^{\circ}C$, while the nitrogen concentration was increased to 42 at%.

• Journal of the Korean Ceramic Society
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• v.30 no.6
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• pp.433-440
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• 1993

The bioactivity of glasses in the CaO-SiO2 system and CaO-P2O5-SiO2 system with less than 10mol% of P2O5 was investigated by in vitro test in simulated body flood(SBF). The formation of Ca.P film and hydroxyapatite on the surface of glasses after in vitro test was analysed by X-ray photoelectron spectoscopy (XPS), fourier transform infrared reflection spectroscopy (FT-IRRS), energy dispersive X-ray spectroscopy (EDS), and scanning electron microscopy (SEM) observation. In the early stage of Ca.P film formation after in vitro test for CaO-SiO2 and CaO-P2O5-SiO2 glasses, the rate of Ca.P film formation on the surface of the glasses was dependent of structural parameter (Y) evaluated from the glass composition. First, in the case of the glasses having Y value below 2, Ca.P film and SiO2-rich layer were formed simultaneously, and there were no differences of the rate of Ca.P film formation in terms of the Y values. Second, in the case of the glasses having Y value above 2, the SiO2-rich layer was formed, and then Ca.P.Si mixed layer was formed in the silica gel structure of the SiO2-rich layer, and finally the Ca.P film on the surface of SiO2-rich layer. The rate of Ca.P film formation delayed as the Y values increased. The rate of hydroxyapatite formation of glasses (the rate of transformation from Ca.P film to hydroxyapatite) seems to be propotional to the rate of Ca.P film formation and Y value. The rate of hydroxyapatite formation of glasses belonging to the second group was delayed as structural parameter increased, and the hydroxyapatite crystal showed spherical growth in the early reaction stage, and then showed silkworm-like linear growth as the reaction time increased.