• Journal of the Mineralogical Society of Korea
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• v.15 no.3
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• pp.231-240
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• 2002

Microbial metal reduction influences the biogeochemical cycles of carbon and metals as well as plays an important role in the bioremediation of metals, radionuclides, and organic contaminants. The use of bacteria to facilitate the production of magnetite nanoparticles and the formation of carbonate minerals may provide new biotechnological processes for material synthesis and carbon sequestration. Metal-reducing bacteria were isolated from a variety of extreme environments, such as deep terrestrial subsurface, deep marine sediments, water near Hydrothemal vents, and alkaline ponds. Metal-reducing bacteria isolated from diverse extreme environments were able to reduce Fe(III), Mn(IV), Cr(VI), Co(III), and U(VI) using short chain fatty acids and/or hydrogen as the electron donors. These bacteria exhibited diverse mineral precipitation capabilities including the formation of magnetite ($Fe_3$$O_4$), siderite ($FeCO_3$), calcite ($CaCO_3$), rhodochrosite ($MnCO_3$), vivianite [$Fe_3$($PO_4$)$_2$ .$8H_2$O], and uraninite ($UO_2$). Geochemical and environmental factors such as atmospheres, chemical milieu, and species of bacteria affected the extent of Fe(III)-reduction as well as the mineralogy and morphology of the crystalline iron mineral phases. Thermophilic bacteria use amorphous Fe(III)-oxyhydroxide plus metals (Co, Cr, Ni) as an electron acceptor and organic carbon as an electron donor to synthesize metal-substituted magnetite. Metal reducing bacteria were capable of $CO_2$conversion Into sparingly soluble carbonate minerals, such as siderite and calcite using amorphous Fe(III)-oxyhydroxide or metal-rich fly ash. These results indicate that microbial Fe(III)-reduction may not only play important roles in iron and carbon biogeochemistry in natural environments, but also be potentially useful f3r the synthesis of submicron-sized ferromagnetic materials.

• Korean Journal of Human Ecology
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• v.9 no.3
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• pp.69-79
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• 2006

The previous studies on the intake of trace elements performed in Korea were only concerned about major elements like Fe, Zn or Cu. There is little data about the intake of minor elements like Mn, Se, Mo or Cr. And most of the data were obtained by calculation using Food Composition Tables or by analysis using atomic absorption spectrophotometers (AAS). The purpose of this study, therefore, was to evaluate the dietary intake of seven trace elements, Fe, Zn, Cu, Mn, Se, Mo, and Cr of Korean adult wonmen and to compare the data between analyzed using ICP-MS (or ICP-AES) and calculated by the CAN-Pro (or Food Composition Table). A total of nineteen adult women participated voluntarily in this study and collected one-tenth of the foods that they consumed for three consecutive days. Analyzed intake of Fe of the subjects was $6.94{\pm}2.18$ (calculated, $18.87{\pm}4.50$) mg/day, that of Ze was $9.35{\pm}4.95$ (calculated, $8.35{\pm}2.87mg/day$), that of Cu was $1.18{\pm}0.26\;(1.11{\pm}0.32mg/day)$, that of Mn was $3.69{\pm}0.69\;(2.83{\pm}1.68mg/day)$, that of Se was $41.93{\pm}9.28$ (calculated, $27.58{\pm}6.97{\mu}g/day$), that of Mo was $134.0{\pm}49.1{\mu}g/day$, and that of Cr was $136.5{\pm}147.9{\mu}g/day$. The analyzed Fe intake of the subjects did not meet Estimated Average Requirement (EAR) nor Recommended Intakes (RI) for Korean women aged 20-29 years old. However, the analyzed intakes of the other six elements, Zn, Cu, Mn, Se, Mo, and Cr, seemed to meet each of the respective RIs. The analyzed Fe intake was significantly lower than the calculated one, in fact by 2.72 times, however, the analyzed intakes of the other elements, Mn and Se, were significantly higher and those of Zn and Cu were similar than each of the calculated ones. The difference of the data between analyzed and calculated intakes indicates that it is necessary to set up database on trace element contents of foods of the Food Composition Table and the CAN-Pro so as to have accuracy.

• Journal of Powder Materials
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• v.24 no.2
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• pp.133-140
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• 2017

This study investigates the oxidation properties of Fe-14Cr ferritic oxide-dispersion-strengthened (ODS) steel at various high temperatures (900, 1000, and $1100^{\circ}C$ for 24 h). The initial microstructure shows that no clear structural change occurs even under high-temperature heat treatment, and the average measured grain size is 0.4 and $1.1{\mu}m$ for the as-fabricated and heat-treated specimens, respectively. Y-Ti-O nanoclusters 10-50 nm in size are observed. High-temperature oxidation results show that the weight increases by 0.27 and $0.29mg/cm^2$ for the as-fabricated and heat-treated ($900^{\circ}C$) specimens, and by 0.47 and $0.50mg/cm^2$ for the as-fabricated and heat-treated ($1000^{\circ}C$) specimens, respectively. Further, after 24 h oxidation tests, the weight increases by 56.50 and $100.60mg/cm^2$ for the as-fabricated and heat-treated ($1100^{\circ}C$) specimens, respectively; the latter increase is approximately 100 times higher than that at $1000^{\circ}C$. Observation of the surface after the oxidation test shows that $Cr_2O_3$ is the main oxide on a specimen tested at $1000^{\circ}C$, whereas $Fe_2O_3$ and $Fe_3O_4$ phases also form on a specimen tested at $1100^{\circ}C$, where the weight increases rapidly. The high-temperature oxidation behavior of Fe-14Cr ODS steel is confirmed to be dominated by changes in the $Cr_2O_3$ layer and generation of Fe-based oxides through evaporation.

• Bulletin of the Korean Chemical Society
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• v.24 no.8
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• pp.1215-1218
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• 2003

An analysis of the bonding situation in CaM₂P₂ (M=Fe, Ni) with ThCr₂Si₂ structure is made in terms of DOS and COOP plots. The main contributions to covalent bonding are due to M-P and P-P interactions in both compounds. Particularly, the interlayer P-P bonding by variation in the transition metal is examined in more detail. It turns out that the shorter P-P bonds in CaNi₂P₂ form as a result of the decreasing electron delocalization into ${{\sigma}_p}^*$ of P₂ due to the weaker bonding interaction between the metal d and ${{\sigma}_p}^*$ as the metal d band is falling from Fe to Ni.

• Journal of Environmental Health Sciences
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• v.29 no.1
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• pp.67-73
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• 2003

This study was carried out to characterize the behavior and sources of particulate trace metal in Daegu city. TSP (Total Suspended Particulate matter) was collected by filters on High Volume Air Sampler from the four areal (reference, residential, commercial, industrial area). The moult were analyzed by AAS after preliminary treatment. The average centration trend of trace metals contained in TSP was shown as follows : Fe > Cu > Pb > Mn > Ni > Cr > Cd. The trace metals showed the highest concentration in the industrial area. This study showed the seasonal variation of trace metals. Fe and Mn showed high concentration in spring, whereas Cr, Ni, Cd and Pb showed high concentration in winter. Also this study showed the regional variation of trace metals. The order of the average concentration of trace metals was : industrial > commercial > residential > reference area. Using Mn as a reference element, the enrichment factor analysis were used for identifying the trace element contributors. The enrichment factors of Cr, Fe < 10 were considered to have a significant dust and soil source and termed nonenriched. Pb, Cd, Cu >>10 were enriched and had a significant fraction which was contributed by anthropogenic sources.

• Journal of Environmental Science International
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• v.7 no.4
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• pp.549-558
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• 1998

determine the distribution of heavy metals in estuarine sediments, forty surface sediment samples were collected from the Youngsan estuary, and analysed for their contents of Fe, Mn, Co, Cr, Cu, Ni, Zn and Pb. Contents of most analysed metals were comparable to those in the near shore environment around Korean peninsula, and little anthropogenic effect was identified. However, there was a contrasting behavior among the metals with respect to their relationship with the grain-size of sediments. Contents of Fe, Co, Cr and Ni demonstrated a fairly linear relationship with the grain-size of sediments whereas those of Mn, Cu, Zn and Pb did not. This different behavior In these metals was Interpreted as being the result of the additional inputs. The R-mode factor analysis also confirmed the different behavior of Cu, Zn, Pb and Mn from that of Fe, Co, Cr and Ni.

• Journal of Powder Materials
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• v.7 no.4
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• pp.197-204
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• 2000

Gas atomization mechanical alloying and hot pressing have successfully made high temperature Al-9.45Fe-4.45Cr alloy. The microstructure and mechanical properties of this alloy has been studied by using optical microscope, scanning electron microscope, transmission electron microscope, X-ray diffractometer and compressive tester. It contains high concentration of transition elements of Fe and Cr, which form thermally stable dispersoids in the aluminum matrix. Proper oxidation of powders during ball milling strengthens the bulk extrudates by providing the obstacle particles. The oxide particles are very chemically and thermally stable and prevent the coarsening of the intermediate compounds.

• Journal of the Korean Society for Heat Treatment
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• v.4 no.4
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• pp.44-52
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• 1991

The effect of deformation temperature and manganes contents on the tensile properties of duplex stainless steels with the structure of both ferrite and austenite were investigate. For this investigation, Fe-19% Cr-5% Ni-4~8% Mn alloys were prepared. The result obtained from this experiment are summerized as follows. With decreasing deformation temperature, tensile strengths of duplex stainless steel increased. Elongation showd to be increased and then decreased after representing the highest value at specific temperature. Tensile properties of duplex stainless steel were controlled by TRIP behavior in this experimental range of austenite contents. Tensile strengths decreased with increasing Mn contents. With increasing Mn contents, elongation decreased in the high temperature region, but increased in the low temperature region. The peak temperature representing the maximum elongation were changed to low temperature and the width of peak appeared to be broaden with increasing Mn contents.

• Journal of the Korean Ceramic Society
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• v.44 no.10
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• pp.554-561
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• 2007

Synthesis and characterization of pigments by using $Fe_2O_3,\;CoO,\;Cr_2O_3\;and\;MnO_2$ were undertaken. The resulting pigments were characterized by using XRD, SEM, FT-IR and UV-Vis spectrophotometer. The color of glazed tiles containing 6 wt% pigment changed from dark green to black depending on the compositions of used materials. Pigments were calcined with mixed materials at $1350^{\circ}C$, and the dark green and dark brown color were obtained. Pigments were used to determine possible interactions between a pigment and a glaze.

• Transactions of Materials Processing
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• v.8 no.3
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• pp.265-265
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• 1999

The development of mechanical alloying (MA)-oxide dispersion strengthened (ODS) heat-resistant ferritic alloys of Fe-12%Cr with W, Ti and Y₂O₃additions were carried out. Fe-12%Cr alloys with 3%W, 0.4%Ti and 0.25% Y₂O₃additions showed a much finer and more uniform dispersion of oxide particles among the alloy system studied. Nano-sized oxides dispersed in the alloys suppress the grain growth during annealing at a high temperature and resulted in the remarkable improvement of creep strength. The oxide phase was identified as a complex oxide type of Y-Ti-O.