• Nuclear Engineering and Technology
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• v.55 no.12
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• pp.4671-4677
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• 2023

For the first time Pb, Ni, and Cu nanocomposites were synthesized by versatile solution combustion synthesis using Aloevera extract as a reducing agent, to study the potential applications in X-ray/gamma, neutron, and Bremsstrahlung shielding. The synthesized Lead-Nickel-Copper (LNC) nanocomposites were characterized by PXRD, SEM, UV-VIS, and FTIR for the confirmation of successful synthesis. PXRD analysis confirmed the formation of multiphase LNC NCs and the Scherrer equation and the W-H plot gave the average crystal sizes of 19 nm and 17 nm. Surface morphology using SEM and EDX confirmed the presence of LNC NCs. Strong absorption peaks were analyzed by UV visible spectroscopy and the direct energy gap is found to be 3.083 eV. Functional groups present in the LNC NCs were analyzed by FTIR spectroscopy. X-ray/gamma radiation shielding properties were measured using NaI(Tl) detector coupled with MCA. It is found to be very close to Pb. Neutron shielding parameters were compared with traditional shielding materials and found LNC NCs are better than lead and concrete. Secondary radiation shielding known as Bremsstrahlung shielding characteristics also studied and found that LNC NCs are best in secondary radiation shielding. Hence LNC NCs find shielding applications in ionizing radiation such as X-ray/gamma and neutron radiation.

• Economic and Environmental Geology
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• v.47 no.4
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• pp.431-439
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• 2014

The purposes of this research were to investigate the enrichment of metal-reducing bacteria from KURT groundwater and the identification of the microbial diversity by 16S rRNA as well as to examine microbial Fe(III)/Mn(IV) reduction and to analyze morphological features of interactions between microbes and precipitates and their mineralogical composition. To cultivate metal-reducing bacteria from groundwater sampled at the KURT in S. Korea, different electron donors such as glucose, acetate, lactate, formate, pyruvate and Fe(III)-citrate as an electron accepter were added into growth media. The enriched culture was identified by 16S rRNA gene sequence analysis for the diversity of microbial species. The effect of electron donors (i.e., glucose, acetate, lactate, formate, pyruvate) and electron acceptors (i.e., akaganeite, manganese oxide) on microbial iron/manganese reduction and biomineralization were examined using the 1st enriched culture, respectively. SEM, EDX, and XRD analyses were used to determine morphological features, chemical composition of microbes and mineralogical characteristics of the iron and manganese minerals. Based on 16S rRNA gene analysis, the four species, Fusibacter, Desulfuromonas, Actinobacteria, Pseudomonas sp., from KURT groundwater were identified as anaerobic metal reducers and these microbes precipitated metals outside of cells in common. XRD and EDX analyses showed that Fe(III)-containing mineral, akaganeite (${\beta}$-FeOOH), reduced into Fe(II)/Fe(III)-containing magnetite ($Fe_3O_4$) and Mn(IV)-containing manganese oxide (${\lambda}-MnO_2$) into Mn(II)-containing rhodochrosite ($MnCO_3$) by the microbes. These results implicate that microbial metabolism and respiratory activities under anaerobic condition result in reduction and biomineralization of iron and manganese minerals. Therefore, the microbes cultivated from groundwater in KURT might play a major role to reduce various metals from highly toxic, mobile to less toxic, immobile.

• Analytical Science and Technology
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• v.23 no.1
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• pp.1-14
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• 2010

It is of importance that all countries in worldwide, including EU and China, have adopted the Restrictions on the use of certain Hazardous Substances (RoHS) for all electronics. IEC62321 document, which was published by the International Electronics Committee (IEC) can have conflicts with the standards in the market. On the contrary Publicly Accessible Specification (PAS) for sampling published by IEC TC111 can be adopted for complementary application. In this work, we tried to find a route to disassemble and disjoint cellular phone sample, based on PAS and compare the screening methods available in the market. For this work, the cellular phone produced in 2001, before the regulation was born, was chosen for better detection. Although X-ray Fluorescence (XRF) showed excellent performance for screening, fast and easy handling, it can give information on the surface, not the bulk, and have some limitations due to significant matrix interference and lack of variety of standards for quantification. It means that screening with XRF sometimes requires supplementary tool. There are several techniques available in the market of analytical instruments. Laser ablation (LA) ICP-MS, energy dispersive (ED) XRF and scanning electron microscope (SEM)-energy dispersive X-ray (EDX) were demonstrated for screening a cellular phone. For quantitative determination, graphite furnace atomic absorption spectrometry (GF-AAS) was employed. Experimental results for Pb in a battery showed large difference in analytical results in between XRF and GF-AAS, i.e., 0.92% and 5.67%, respectively. In addition, the standard deviation of XRF was extremely large in the range of 23-168%, compared with that in the range of 1.9-92.3% for LA-ICP-MS. In conclusion, GF-AAS was required for quantitative analysis although EDX was used for screening. In this work, it was proved that LA-ICP-MS can be used as a screening method for fast analysis to determine hazardous elements in electrical products.

• Journal of Environmental Science International
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• v.22 no.1
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• pp.7-15
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• 2013

Aerosol characterization study for individual particle in Busan metropolitan industrial complex was carried out from December 2010 to August 2011. SEM(scanning electron microscope)-EDX(energy dispersive x-ray) analysis was used for the analysis of 600 single particles during the sampling periods to identify non-metallic aerosol particle sources. Average $PM_{10}$ concentration was 65.5 ${\mu}g/m^3$ in summer, 104.1 ${\mu}g/m^3$ in winter during the sample periods. And Average $PM_{2.5}$ concentration was 24.5 ${\mu}g/m^3$ in summer, 64.5 ${\mu}g/m^3$ in winter individually. Particle density, enrichment factor, correlation analysis, principle component analysis were performed based on chemical composition data. Particle density distribution was measured to 2~4 $g/cm^3$, and the density of $PM_{2.5}$ was measured above 3 $g/cm^3$. In general, the elements Si, Ca, Fe and Al concentrations were higher in all samples of individual particles. The non-ferrous elements Zn, Br, Pb, Cu concentrations were higher in summer than in winter. The concentrations were not changed with the seasons because of non-ferrous industry emission pattern.

• Journal of Conservation Science
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• v.32 no.1
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• pp.75-88
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• 2016

In this study, 5 mural paintings in the Buddhist temples of Joseon era were researched for component analysis on the soil contained in the walls. The results of particle size analysis showed that the ratio of particle contents were different in each layer. In the finishing layer, the distribution of the middle sand fraction is higher than that of the middle layer. The results of XRD analysis showed that quartz, feldspar, and clay mineral are the main components of sand, suggesting similar mineral composition to that of ordinary soil component. It seems weathered rocks were used for construction of the walls. The main chemical components detected from EDX analysis were Si, Al, Fe, and K. Also the SEM images showed sand or clay sized minerals. In conclusion, the walls of the buddhist mural paintings in Joseon Dynasty had been constructed by using the loess, and had been produced by using mixture of clay and sand particles of different sizes for each layer. This study identified the characteristics of the materials and the manufacturing technologies used on the walls of mural paintings of Buddhist temples in Joseon era.

• Journal of Periodontal and Implant Science
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• v.34 no.1
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• pp.1-17
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• 2004

It is improtant that performing prophylaxis procedure on an infected implant surface in order to treat peri-implantitis should not change the surface roughness and composition, so that the surface can be recovered to almost same condition as initial implant surface. This thesis, therefore, studied an effect of various oral hygiene instrument on implant surface. A surface roughness measurement instrument and an infection electron microscope were used to observe a change on surface. The purpose of this study was to obtain a clinical guidelines during implant care and peri-implantitis treatment. The result were as follows 1. Ra values (surface roughness value) at experimental group 1, group 2, and group 5 were increased significantly as compared with comparison group(p<0.05). 2. When compared experimental group 1 with each experimental groups at which prohylaxis procedure was performed, mean values of Ra at experimental group 2, group 3, group 6, and group 7 were decreased significantly(p<0.05). 3. Mean value of Ra was lowest at experimental group 2, and highest at experimental group 2, and highest at experimental group 5. 4. Analysis of SEM showed that was significant surface change at experimental group 2, group 3, group 4, group 5, and group 6 as compared with comparison group(X1000). 5. Analysis fo EDX showed that a quantity of Ti on surface for experimental group 6 was very similar to that for comparison group. In conclusion, air-powder abrasive and citric acid, plastic instrument are safe methods to use for performing prophylaxis procedure on implant care or for cleaning and sterilization process on treatment of peri-implantitis, based on the result that those method did not affect implant surface roughness and Ti composition.

• Archives of Plastic Surgery
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• v.33 no.3
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• pp.324-329
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• 2006

The silicone rubber implants are widely used in plastic surgery because of various advantages; however, calcification in surface of implant(as a chemical resistance) may transform or destroy the high molecular biomaterial when it stays too long within the human body. The purpose of this study is to determine the relationship between calcification and the histological disparities of the tissues surrounding the area adjoining the silicone nasal implant by examining the regional characteristics of calcium deposits in the silicone nasal implant via elemental analyses using EDX(energy-dispersive X-ray analysis) and ultrastructural analyses using SEM(scanning electron microscopy). The subjects of the study were 19 silicone nasal implants removed by revision rhinoplasty, all displaying calcification. According to the tissue characters, the implant surface was divided into 4 zones with the rhinion as the basis. For each zone, elemental and ultrastructural analyses were performed. Elemental analysis revealed that the calcium deposits consisted of Ca and P only. There were no statistically significant disparities among the ratios between Ca and P according to the zones. Ultrastructural analysis showed acellular mineral-like deposits coalesced to create amorphous deposits in all zones; however, in zones 1 and 3(more pressurized zones by periosteum or nasal bone), additional flaky cylinder-shaped calcium deposits were detected. Thus, it seems that the histological disparities in the surrounding tissues do not affect the components and their proportions in the calcification process. However, it can be inferred that the physical environment due to the histological disparities in the surrounding tissues affects the ultrastructures of calcium deposits.

• Journal of the Korean Geotechnical Society
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• v.21 no.6
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• pp.117-126
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• 2005

The chemical property analysis on the deposited clay using scanning electron microscope and energy dispersive x-ray spectrometer were performed. Also, the triaxial compression tests and consolidation tests using NaCl aqueous solution and leachate as substitute pore (or saturated) water in samples were carried out to find out the behaviour characteristics of strength and deformation of contaminated deposited clay. from the chemical composition analysis results of clay samples, the magnitudes of composition ratio were revealed in the order of O, C, Si, Al, and Fe. Of these, why the ratio of carbon appeared to be large is estimated as due to the increase of the phyto-planktons after the construction of tide embankment. In the triaxial compression test and consolidation test results, the shear strength and compression properties have increased with the increase in concentration of contaminant (NaCl). This phenomenon is considered as to be caused by the changes of soil structure to flocculent structure owing to the decrease in the thickness of diffuse double layer in proportion to increase in the concentration of electrolyte.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.3
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• pp.285-291
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• 2011

Membrane fouling is an unavoidable phenomenon and major obstacle in the economic and efficient operation under sea water reverse osmosis (SWRO). When fouling occurs on the membrane surface, the permeate quantity and quality decrease, the trans-membrane pressure (TMP) and operation costs increase, and the membrane may be damaged. Therefore, chemical cleaning process is important to prevent permeate flow from decreasing in RO membrane filtration process. This study focused on proper chemical cleaning condition for Shuaibah RO plant in Saudi Arabia. Several chemical agents were used for chemical cleaning at different contact time and concentrations of chemicals. Also autopsy analysis was performed using LOI, FT-IR, FEEM, SEM and EDX for assessment of fouling. Specially, FEEM analysis method was thought as analyzing and evaluating tool available for selection of the first applied chemical cleaning dose to predict potential organic fouling. Also, cleaning time should be considered by the condition of RO membrane process since the cleaning time depends on the membrane fouling rate. If the fouling exceeds chemical cleaning guideline, to perfectly remove the fouling, certainly, the chemical cleaning is increased with membrane fouling rate influenced by raw water properties, pre-treatment condition and the point of the chemical cleaning operation time. Also choice of cleaning chemicals applied firstly is important.

• Journal of Technologic Dentistry
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• v.25 no.1
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• pp.9-20
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• 2003

Using a nickel-chrome casting alloy called 'Rexillium V' which is also available as base metal alloy for dental ceramic crown, 4 types of mixtures(A, B, C, D) with old and new metal were prepared for cyclic casting. The results of cyclic casting can be outlined as follows: 1. For Vickers hardness after casting, specimen A and D tended to have lower hardness in the course of cyclic casting, while specimen B and C tended to higher hardness. 2. The results of X-ray diffraction analysis showed that major crystal phase contained nickelchrome compounds and carbide. 3. The observation results of SEM photographs after cyclic casting show that there was a significant tendency to have similar structures among experimental groups. 4. The results of EDX analysis after cyclic casting showed that there were little differences in chemical composition between parent metal and base metal alloy. Although industrial nickel-chrome cast alloy did not show any significant change in material properties even through cyclic casting over several times, it is recommended that more there be more in-depth studies on how to detect any potential corrosion, discoloration and toxication of dental ceramic crown implanted in patient's oral cavity.