• Nuclear Engineering and Technology
• /
• v.54 no.3
• /
• pp.1062-1070
• /
• 2022

In the present communication, pure and stable α-Bismuth Oxide (Bi₂O₃) nanoparticles (NPs) were synthesized by low temperature solution combustion method using urea as a fuel and calcined at 500℃. The synthesized sample was characterized by using powder X-ray Diffraction (PXRD), Scanning Electron Microscopy (SEM), Energy dispersive X-ray analysis (EDAX), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR) and UV-Visible absorption spectroscopy. The PXRD pattern confirms the formation of mono-clinic, stable and low temperature phase α-Bi₂O₃. The direct optical energy band gap was estimated by using Wood and Tauc's relation which was found to be 2.81 eV. The characterized sample was studied for X-ray/gamma ray shielding properties in the energy range 0.081-1.332 MeV using NaI (Tl) detector and multi channel analyzer (MCA). The measured shielding parameters agrees well with the theory, whereas, slight deviation up to 20% is observed below 356 keV. This deviation is mainly due to the influence of atomic size of the target medium. Furthermore an accurate theory is necessary to explain the interaction of X-ray/gamma ray with the NPs.The present work opens new window to use this facile, economical, efficient, low temperature method to synthesize nanomaterials for X-ray/gamma ray shielding purpose.

• Korean Chemical Engineering Research
• /
• v.61 no.2
• /
• pp.287-295
• /
• 2023

Iron nanoparticles (Fe-NPs) were synthesized employing Lagenaria siceraria (LS) leaf aqueous extract as a reducing and capping medium to remove methylene blue (MB) dye and have antibacterial properties against G-negative (Escherichia coli) and G-positive bacteria (Staphylococcus aureus). The formation of LS-Fe-NPs (Lagenaria-siceraria-iron-nanoparticles) was confirmed by a change in color from pale yellow to dark brown. Characterization techniques, such as particle size analysis (PSA), transmission electron microscopy (TEM) and scanning electron microscopy (SEM), were employed to prove nano spherical particles of size range between 80-100 nm. Phytochemicals and the presence of iron in LS-Fe-NPs nanoparticles were proved by UV-visible spectrophotometry. Further, Fourier transform infrared spectroscopy (FTIR) analysis results confirmed the existence of bioactive molecules in the plants. The magnetic property was analyzed using a vibrating sample magnetometer (VSM), which displayed that the synthesized nanoparticles were superparamagnetic and exhibiting a saturation magnetization of 12.5 emu/g. Synthesized magnetic nanoparticles were used in methylene blue (MB) dye removal through adsorption. About 83% of 100 mg/L MB dye was removed within 120 min at pH 6 with a maximum adsorption capacity of 246.8 mg/g. Antibacterial efficacy of LS-Fe-NPs was screened against G-negative (Escherichia coli) and G-positive bacteria (Staphylococcus aureus), respectively, and found that LS-Fe-NPs were effective against Staphylococcus aureus.

• Advances in nano research
• /
• v.15 no.4
• /
• pp.295-304
• /
• 2023

In this paper, a powerful photocatalyst based on carbon nanocomposite is developed in order to obtain a new material applicable in water treatment and especially for the discoloration of effluents used in the textile industry. For that, TiO₂-graphene nanocomposites have been successfully synthesized by a mixture of Functionalized Graphene Sheet (FGS) and tetrachlorotitanium complexes to form FGS-TiO₂ nanocomposite. In the presence of an anionic surfactant, we used a new chemical process to functionalize graphene sheets in order to make them an excellent medium for blocking and preventing the aggregation of TiO₂ nanoparticles. The components of these nanocomposites are characterized by means of X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM), which confirms the successful formation of the FGS-TiO₂ nanocomposite. It was found that the TiO₂ nanoparticles were dispersed uniformly on the graphene plane which possesses better charge separation capability than pure TiO₂. The FGS-TiO₂ nanocomposites exhibited higher photocatalytic activity compared to pure TiO₂ for the removal of three dyes: such as Methylene Blue (MB), Bromophenol Blue (BB) and Alizarin Red-S (AR) in water. The removal process was fast and more efficient with FGS-TiO₂ nanocomposite in daylight (in the absence of UV irradiation) compared to pure TiO₂ nanoparticles without and under UV in all pH range.

• Advances in nano research
• /
• v.16 no.1
• /
• pp.41-52
• /
• 2024

In this study, rare-earth orthoferrites LnFeO₃ were synthesized using a facile hydrothermal reaction and their visible-light-induced photo-Fenton degradation of organics was optimized through Ln variation (Ln = La, Pr, or Gd). The morphological, structural, and chemical characteristics of as-prepared samples were examined in detail by using different methods, including XRD, SEM, TEM, XPS, etc. On the other side, under visible light illumination, the photo-Fenton-like catalytic activities of LnFeO₃ were assessed in terms of the removal of selected organic models, i.e., pharmaceuticals (ketoprofen and tetracycline) and dyes (rhodamine B and methyl orange). As compared with PrFeO₃ or GdFeO₃, the sample of LaFeO₃ displayed more structural distortion, larger specific surface area, and narrower band gap, resulting in its higher photo-Fenton-like catalytic activity toward the degradation of organics. In organic-containing solution, in which the initial solution pH = 5, catalyst dosage = 1 g/L and H₂O₂ concentration = 10 mM, 98.2% of rhodamine B, 31.1% of methyl orange, 67.7% of ketoprofen, or 96.4% of tetracycline was removed after 90-min exposure to simulated visible light. Our findings revealed that variation of Ln site on rare-earth orthoferrites was an effective strategy for optimizing their organic removal via visible-light-induced photo-Fenton reaction.

• The Journal of Engineering Research
• /
• v.3 no.1
• /
• pp.189-197
• /
• 1998

Hyeroxyapatite(HAp) which has good biocompatibility was made by Wet Chemical Process. The surface of Ti-6Al-4V, coated with HAp by lon Beam Assisted Deposition (IBAD), was treated with 5ppm, 10ppm, 20ppm, and 100ppm of $AgNO_3$ solution. In this Ag impregnation process, $Ca^{2+}$ of HAp was substituted with $Ag^+$ of $AgNO_3$. In this study, the antimicrobial effect and biocompatibility of Ti-6Al-4V alloy which was coated with Ag-HAp were examined. The antimicrobial test was carried out with two kinds of bacteria(P. Aeruginosa, S. Epidermidis), which are highly infectious in a transplanting operation of implant materials. As a result of the test, it was observed that Ti-6Al-4V alloy which was treated by 20ppm of $AgNO_3$ solution has good biocompatibility. In order to observe the antimicrobial mechanism of $Ag^+$, E. coli which is the most common bacterium was treated by Ag-HAp. Then cell morphology of E. coli was observed by the transmission electron microscope(TEM). The destruction of cell wall and cytoplasm of E. coil were observed. A black spot appeared in the cytoplasm was analyzed by energy dispersive analysis X-ray (EDAX) and it showed a small amount of $Ag^+$. Thus, it was proved that $Ag^+$ destroys bacteria effectively and Ti-6Al-4V alloy which was impregnate with Ag ion show antimicrobial effect on infection bacteria.

• Journal of the Korean Applied Science and Technology
• /
• v.37 no.5
• /
• pp.1285-1297
• /
• 2020

In this study, we report the results of a study on the clinical evaluation of wrinkle improvement by developing a method for liposome of high-purity Centella asiatica extract used in pharmaceuticals and cosmetics, and a cream using the same. In order to make Centellasome-10EX stabilizing centella asiatica extract in liposome lamella vesicle, it could be completed using 5% hydrogenated lecithin and 2% sucrose distearate. The appearance of Centellasome-10EX was a creamy form of low viscosity, the color was pale yellow, and the odor had the inherent odor of the raw material. The pH was about 6.12, the specific gravity was 1.09, and the acid value was about 0.35. The content of the main constituents of centella asiatica extract contained in the liposome vesicle contains 10,800 ppm of asiatic acid, 10,900 ppm of asiaticoside, 6,000 ppm of madecasic acid, and 1,600 ppm of madecassoside, and long-term storage. There was no discoloration even at the time, and it was found that the main component remained stable thermodynamically. To mechanistically analyze the structure of the liposome vesicle of Centellasome-10EX, as a result of observation with a transmission electron microscope (Cryo-TEM), the multilayer vesicles are formed and filled with moisture, and there are 10 to 60 multilayers around it. It was confirmed that the liposome lamella vesicle was formed. As a clinical trial (in-vivo) test, the moisturizing effect of centellasome cream after application for 5 weeks was 28.3%, which was significantly increased compared to placebo. The skin elasticity effect was 13.6%, which significantly increased the moisturizing power than the placebo. The effect of improving fine wrinkles around the eyes was improved by 23.52% compared to placebo cream. Through the results of this study, it was possible to study the formulation and manufacturing method for encapsulation and stabilization of the developed Centellasome-10EX in the liposome vesicle. It is expected that the results obtained through clinical research on the wrinkle improvement effect of the cream using this can be widely used to study skin science in the cosmetic industry and to develop high-quality cosmetics with high efficacy.

• Clean Technology
• /
• v.25 no.1
• /
• pp.81-90
• /
• 2019

A dielectric barrier discharge (DBD) plasma reactor packed with $Ni-CeO_2/{\gamma}-Al_2O_3$ catalyst was used for the dry ($CO_2$) reforming of propane (DRP) to improve the production of syngas (a mixture of $H_2$ and CO) and the catalyst stability. The plasma-catalytic DRP was carried out with either thermally or plasma-reduced $Ni-CeO_2/{\gamma}-Al_2O_3$ catalyst at a $C_3H_8/CO_2$ ratio of 1/3 and a total feed gas flow rate of $300mL\;min^{-1}$. The catalytic activities associated with the DRP were evaluated in the range of $500{\sim}600^{\circ}C$. Following the calcination in ambient air, the ${\gamma}-Al_2O_3$ impregnated with the precursor solution ($Ni(NO_3)_2$ and $Ce(NO_3)_2$) was subjected to reduction in an $H_2/Ar$ atmosphere to prepare $Ni-CeO_2/{\gamma}-Al_2O_3$ catalyst. The characteristics of the catalysts were examined using X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectrometry (EDS), temperature programmed reduction ($H_2-TPR$), temperature programmed desorption ($H_2-TPD$, $CO_2-TPD$), temperature programmed oxidation (TPO), and Raman spectroscopy. The investigation revealed that the plasma-reduced $Ni-CeO_2/{\gamma}-Al_2O_3$ catalyst exhibited superior catalytic activity for the production of syngas, compared to the thermally reduced catalyst. Besides, the plasma-reduced $Ni-CeO_2/{\gamma}-Al_2O_3$ catalyst was found to show long-term catalytic stability with respect to coke resistance that is main concern regarding the DRP process.

• Journal of Technologic Dentistry
• /
• v.10 no.1
• /
• pp.159-169
• /
• 1988

Fixed prosthetic appliance is the restorations of damaged teeth with cast metal or porcelain, and of replacing missing teeth with fixed, or cemented prosthesis. Successfully treating a patient by means of fixed prosthodontics requires the thoughtful combination of dentist and dental laboratory technician. In order to know the satisfaction of dentisits about fixed prosthetic appliances-porcelain, precious and non precious metal-, this study was conducted for 69 practicing dentisis in Pusan during Fed. to Mar. 1988 using a questionnaire method and was analyzed by the use of percentage, $X^2$-test The results are obtained as follow: 1. General characteristics of the respondents, The rate of age distribution of practcing dentists responded was as follow : 31$\sim$35 age group is 29.0%, 51$\sim$55age group 18.8%, 41$\sim$45 age group and 46$\sim$50 group each 11.6%, 36$\sim$40 age group and 56$\sim$60 age group 8.7%, over 60 age group 7.3%, below 30 age group 4.3% respectively. The tate of term of practice experience distribution of dentists responded was as follow : 6$\sim$10 year group 26.1%, 25$\sim$25year group 18.8%, 11$\sim$15 years group and 16~20 years group each 13.0%, below 5 years group and over 30 years group each 10.2%, 26$\sim$30 years group 8.7% in order. The rate of respondents’ degree was follow : bachelor group 81.2%, doctor group 13.0%, master group 5.8% in order. The rate of respondents’completed medical specialist course was as follow : non-complete group 75.4%, complete group 24.6%. The rate of having own laboratory in respondents’clinic was as follow : no having own laboratory group 58.0%, having own labiratory group 42.0% The rate of being lab. technician in respondent;s clinic was as follow: non-being lab. technician group 91.3%, being lab. technician group 8.7%. The rate of transactional commercial dental lab. numbers was as follow : I dental lab. group 40.6%, 2 dental lab. group 30.4%, 3 dental lab. group 20.3%, production at own lab. group 8.7% 2. Cognitions about the respondent's job, About cognition of patient numvers, there were neither many nor few group 62.3%, few group 17.4%, many group 15.9%, too many group 4.4% in order.(P<.01) As compared with the ratio of dentists to patient prothetic treatment, there were moderate level group 46.4%, high level group 33.6%, low level group 18.8% in order.(P<.01) By job satisfaction of respondents, the highest percentage group was satisfied group 44.9%, neither astisfied nor disstified group 33.3%, dissatisfied group 14.5%, much satisfied group 7.3%(P<.01). As compared with the level of prosthetics price, the were moderate level group 71.0%, low level group 23.2%, high level group 5.8%(P<.01) 3. Satisfaction and assessment of dissatisfied factor of the fixed prosthetic appliance, As compared with the satisfaction of al prosthetic appliance, there were neither satisfied nor dissatisfied group 59.4%, satisfied group 20.3% dissatisfied group 18.8%, much satisfied group 1.5% in order.(P<.01). About precious and non precious metal crown and bridge, there were neither satisfied nor dissatisfied group 60.9%, satisfied group 24.6%, dissatisfied group 11.6%, much satisfied group 2.9% in order.(P<.01) The reat of respondent;s satisfaction about porcelain crown and bridge was as follow : neither satisfied nor dissatisfied group 43.5%, dissatisfied group 33.3%, satisfied group 21.7%, much satisfied group 1.5%(P<.01). The rate of respondent's dissatisfied factor item of precious and non precious metal crown and bridge was as follow : inadequate margin fit item 39.1% respondent, inadequate occlusion item 24.6%, inadequate adaptation item 23.2%, poor anat omic form item 15.9%, inadequate contact item 31.9%, improper polishing item 4.4%, the rest item 11.6% respectively. The rate of respondent's dissatisfied factor item of porcelain crown and bridge was as follow : inadequate margin fit item 52.2%, inadequate occlusion item 2.9%, inadequate adaptation item 10.1%, poor anatomic form item 11.6%, improper polishing item 1.5%, shade mismatching item 71%, the rest item 7.2% respectively. The rate of cognition of respondents’ about cause of dissatisfied factor on fixed prosthetic appliance by item was as follow : deficiency of sincerity item 55.1%, deficiency of knowledge about work item 47.8%, deficiency of experience item 15.9%, poor quality of using material item 5.8%, the rest item 2.9% respectively.

• The Korean Journal of Malacology
• /
• v.26 no.1
• /
• pp.63-78
• /
• 2010

The purpose of this study was to investigate the effect of tributyltin (TBT) on histopathological and ultrastructural changes in the digestive gland structure of the equilateral venus, Gomphina veneriformis. Experimental period was 36 weeks. Experimental groups consist of control condition and 3 TBTCl exposure conditions (0.4, 0.6, $0.8\;TBTC\;{\mu}g\;L^{-1}$). Outer envelop of the visceral mass of G. veneriformis exposed to TBTCl was observed disappearance of microvilli and cilia, decrease of mucous cell and partially destruction of epithelium. In the digestive gland showed an increase of number of hemocyte and mucopolysaccaride near the digestive tubule at early time of the exposure. Especially, in $0.8\;TBTC\;{\mu}g\;L^{-1}$ group, collapse of digestive tubule with modification of epithelium was observed. TEM observation revealed the numerous glycogen granules in epithelium of the outer envelop and connective tissue. In the ciliated cell of the primary duct formed the cilia in cytoplasm. Basophilic cell was observed destruction of the rough endoplasmic reticulum and mitochondria. Also, nucleus in the epithelium of the digestive tubule was disappeared heterochromatin and nucleolus, and condense. As the concentration of TBTCl increased, the accumulation of lipofucin increased in the digestive gland, but the collapse of digestive tubule induced a decrease of accumulation of lipofuscin.

• Journal of the East Asian Society of Dietary Life
• /
• v.22 no.1
• /
• pp.109-119
• /
• 2012

This study analyzed the antibacterial activity of the ethanol extract of Schizandra chinensis Baillon against food pathogenic microorganisms to determine its capabilities as a natural antimicrobial agent. A paper disc diffusion test, minimum inhibitory concentration (MIC) determination, and time-kill assay showed that the ethanol extract strongly inhibits the growth of Listeria monocytogenes, Bacillus cereus, Escherichia coli O157:H7, and Pseudomonas aeruginosa. Release of cytoplasmic ${\beta}$-galactosidase was detected in E. coli, E. coli O157:H7, S. aureus, and P. aeruginosa treated with the ethanol extract. An increase of outer membrane permeability caused by the ethanol extract was also observed. An outward flow of cell constituents was detected in the Gram negative strains treated with the ethanol extract. These results imply that the inner and outer membranes of cells were partially destroyed and cell constituents were released by the treatment of the S. chinensis Baillon ethanol extract. The results of this study indicate that ethanol extract of S. chinensis Baillon evidences a fairly good antibacterial effect.