• Bulletin of the Korean Chemical Society
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• v.15 no.1
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• pp.79-83
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• 1994

The organometallic chemical vapor deposition of single precursors, $[Me_2Al({\mu}-NHR)]_2\;(R=^iPr,\;^tBu)$, for alumininum nitride thin films has been investigated to evaluate their poroperties as potential precursors. In chemical vapor deposition processes the gas phase products scattered from a Ni(100) substrate were analyzed by mass spectrometry and the deposited films were characterized by X-ray photoelectron spectroscopy (XPS). The optimum temperatures for the formation of AlN films have been found to be between 700 K and 800 K. Carbon contamination of the films seems to be attributed mainly to the methyl groups bonded to the aluminum atoms. It is apparent that $^tBu$ group is better than $^iPr$ group as a substituent on the nitrogen atom of the single precursors for the AlN thin film formation.

• Nuclear Engineering and Technology
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• v.53 no.11
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• pp.3474-3490
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• 2021

Sodium-cooled fast reactor (SFR) is the preferred technology of the generation-IV fast neutron reactor, and its core body mainly uses nuclear-grade 316 stainless steel. In order to prolong the design life of SFRs to 60 years and more, it is necessary to summarize and analyze the anti-corrosion effect of nuclear grade 316 stainless steel in high temperature sodium environment. The research on sodium corrosion of nuclear grade 316 stainless steel is mainly composed of several important factors, including the microstructure of stainless steel (ferrite layer, degradation layer, etc.), the trace chemical elements of stainless steel (Cr, Ni and Mo, etc) and liquid impurity elements in sodium (O, C and N, etc), carburization and mechanical properties of stainless steel, etc. Through summarizing and constructing the sodium corrosion rate equations of nuclear grade 316 stainless steel, the stainless steel loss of thickness can be predicted. By analyzing the effects of temperature, oxygen content in sodium and velocity of sodium on corrosion rate, the basis for establishing integrity evaluation standard of SFR core components with sodium corrosion is provided.

• Corrosion Science and Technology
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• v.20 no.6
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• pp.361-366
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• 2021

Localized corrosion behavior of Ni-based Inconel 718 alloy was investigated by electrochemical anodic polarization techniques in NACE TM 0177 A solution of 5 wt% NaCl + 0.5 wt% acetic acid at room temperature. After the solution heat treated at 1080 ℃ for 2.5 h, Inconel 718 was age-hardened at 780 ℃ for 8 h. The microstructure of the alloy surface was investigated by optical microscopic or scanning electron microscopic technique. The austenitic phase with the presence of metal carbides was observed on the surface of Inconel 718. Metal-carbides such as Nb-Mo and Ti-carbide with diameters of approximately 10 and 3 ㎛, respectively, were formed in Inconel 718. Anodic polarization results revealed that localized corrosion was observed at the interface between austenitic phase of a substrate and metal carbides. Difference in electrochemical property between a metal carbide and an austenitic substrate could provide an initiation site for localized corrosion of Inconel 718 surface.

• Corrosion Science and Technology
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• v.23 no.4
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• pp.255-265
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• 2024

Duplex stainless steels (UNS S32205, UNS S32750) are used in various environments. The potentiodynamic polarization tests were conducted at 30 ℃ in order to study the electrochemical corrosion behaviors of duplex stainless steels under different seawater concentrations (fresh water, seawater, mixed water). The results of Tafel analysis in seawater showed that UNS S32205 and UNS S32750 had the highest corrosion current densities at 6.12 × 10^-4 mA/cm² and 5.41 × 10^-4 mA/cm², respectively. The pitting potentials of UNS S32205 and UNS S32750 were comparable to or higher than the oxygen evolution potential in fresh water, mixed water, and seawater. The maximum damage depths and surface damage ratio caused by pitting corrosion increased with chloride concentration. The synergy effect of molybdenum and nitrogen enhances the concentration of Mo, Ni, and Cr at the interface of the metal-electrolyte. In particular, in the case of nitrogen, NH₃ and NH₄⁺ are formed to compensate for the pH drop in the pitting region, thereby strengthening the repassivation of the film. The excellent corrosion resistance of UNS S32750 is attributed to the strengthening effect of the chromium oxide film due to the presence of molybdenum and nitrogen.

• Asian-Australasian Journal of Animal Sciences
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• v.30 no.5
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• pp.736-742
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• 2017

Objective: Experiments were conducted to clone the sequence of Wild Argali short palate, lung and nasal epithelium clone 1 (SPLUNC1) cDNA, and to lay the foundation for further study the biological function of Wild Argali SPLUNC1. Methods: The complete sequence of Wild Argali SPLUNC1 cDNA was generated by rapid amplification of cDNA ends. The entire coding sequence was inserted into the pPIC9K vector and expressed in Pichia pastoris (P. pastoris) GS115. The recombinant SPLUNC1 protein was detected by Western blot and purified by $Ni^{2+}$ chelate affinity chromatography. The test of effect of the protein on Mycoplasma ovipneumoniae (MO) was performed with real-time polymerase chain reaction. Results: The Wild Argali SPLUNC1 cDNA was 1,076 bp with an open reading frame of 768 bp, which encoded a 26.49 kDa protein composed of 255 amino acids. Its amino acid sequence shared 98.4%, 96.9%, 94.5%, 90.2%, 80.8%, 78.4%, 78.3%, 72.5%, 72.3%, 68.8% identity with those of SPLUNC1 cDNA from Ovis aries (accession no. NP_001288334.1), Capra hircus (accession no. XP_005688516.1), Pantholops hodgsonii (accession no. XP_005979709.1), Bos taurus (accession no. NP_776851.1), Felis catus (accession no. XP_006929910.1), Homo sapiens (accession no. NP_001230122.1), Sus scrofa (accession no. NP_001005727.1), Chinchilla lanigera (accession no. NP_001269294.1), Mus musculus (accession no. NP_035256.2), and Rattus norvegicus (accession no. NP_742028.1), respectively. The recombinant protein corresponded to the expected molecular mass of 25.47 kDa as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and it was detected in the supernatant of P. pastoris, and it could be purified. The results from the test of inhibition effect of argali recombinant SPLUNC1 protein on MO showed that the product could inhibit MO very well (p<0.01). Conclusion: The amino acid sequence of Wild Argali SPLUNC1 was different from other organisms. The recombinant SPLUNC1 protein has good biological activity.

• The Journal of Korean Academy of Prosthodontics
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• v.31 no.3
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• pp.423-446
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• 1993

Titanium and its alloys are finding increasing use in medical devices and dental implants. The strong selling point of titanium is its resistance to the highly corrosive body fluids in which an implant must survive. This corrosion resistance is due to a tenacious passive oxide or film which exists on the metal's surface and renders it passive. Potentiodynamic polarization measurement is one of the most commonly used electro-chemical methods that have been applied to measure corrosion rates. And the potentiodynamic polarization test supplies detailed information such as open circuit, rupture, and passivation potential. Furthermore, it indicates the passive range and sensitivity to pitting corrosion. This study was designed to compare the corrosion resistance of the commonly used dental implant materials such as CP Ti, Ti-6A1-4V, Co-Cr-Mo alloy, and 316L stainless steel. And the effects of galvanic couples between titanium and the dental alloys were assessed for their useful-ness-as. materials for superstructure. The working electrode is the specimen , the reference electrode is a saturated calomel electrode (SCE), and the counter electrode is made of carbon. In $N_2-saturated$ 0.9% NaCl solutions, the potential scanning was performed starting from -800mV (SCE) and the scan rate was 1 mV/sec. At least three different polarization measurements were carried out for each material on separate specimen. The galvanic corrosion measurements were conducted in the zero-shunt ammeter with an implant supraconstruction surface ratio of 1:1. The contact current density was recorded over a 24-hour period. The results were as follows : 1. In potential-time curve, all specimens became increasingly more noble after immersion in the test solution and reached between -70mV and 50mV (SCE) respectively after 12 hours. 2. The Ti and Ti alloy in the saline solution were most resistant to corrosion. They showed the typical passive behavior which was exhibited over the entire experimental range. Therefore no breakdown potentials were observed. 3. Comparing the rupture potentials, Ti and Ti alloy had the high(:st value (because their break-down potentials were not observed in this study potential range ) followed by Co-Cr-Mo alloy and stainless steel (316L). So , the corrosion resistance of titanium was cecellent, Co-Cr-Mo alloy slightly inferior and stainless steel (316L) much less. 4. The contact current density sinks faster than any other galvanic couple in the case of Ti/gold alloy. 5. Ag-Pd alloy coupled with Ti yielded high current density in the early stage. Furthermore, Ti became anodic. 6. Ti/Ni-Cr alloy showed a relatively high galvanic current and a tendency to increase.

• Korean Journal of Materials Research
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• v.7 no.3
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• pp.218-223
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• 1997

At the aim of finding a Fehased amorphous alloy with a wide supercooled liquid region (${\Delta}T_{x}=T_{x}-T_{g}$) before crystallization, the changes in glass transition temperatudfI$T_{g}$ and crystallization temperature ($T_{x}$) by the dissolution of additional M elements were examined for the $Fe_{80}P_{10}C_{6}B_{4}$(x~6at%. M= transition metals) amorphous alloys. The ${\Delta}T_{x}$ value is 27K for the Fe,,,P,,,C,,R, alloy and increases to 40K for the addition of M=4at%Hf, 4at%Ta or 4at%Mo. The increase in ${\Delta}T_{x}$ is due to the increase of $T_{x}$ exceeding the degree in the increase in $T_{g}$. The $T_{g}$ and $T_{x}$ increase with decreasing electron concentration (e/a) from about 7 38 to 7.05. The decrease of e/a also implies the increase in the attractive bonding state between the M elements and other constitutent elements. It is therefore said that $T_{g}$ and $T_{x}$ increase kith increasing attractive bonding force.

• Journal of Biomedical Engineering Research
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• v.25 no.2
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• pp.157-163
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• 2004

Nitrogen ion implantation and ion plating techniques were applied for improvement of the wear resistance of metallic implant materials. In this work, the wear dissolution behaviour of a nitrogen ion implanted super stainless steel (S.S.S, 22Cr-20Ni-6Mo-0.25N) was compared with those of S.S.S, 316L SS and TiN coated 316L SS. The amounts of Cr and Ni ions worn-out from the specimens were Investigated using an electrothermal atomic absorption spectrometry. Furthermore, the Ti(Grade 2) disks were coated with TiN, ZrN and TiCN by use of low temperature arc vapor deposition and the wear resistance of the coating layers was compared with that of titanium. The chemical compositions of the nitrogen ion implanted and nitride coated layers were examined with a scanting auger electron spectroscopy. It wat observed that the metal ions released from the nitrogen ion implanted S.S.S surface were significantly reduced. From the results obtained, it was shown that the nitrogen ion implanted zone obtained with 100 KeV ion energy was easily removed within 200,000 revolutions from a wear dissolution testing under a similar load condition when applied to artificial hip joint. The remarkable improvement in wear resistance weir confirmed by the nitrides coated Ti materials and the wear properties differ greatly according to the chemical composition of the coating layers. for specimens with the same coating thickness of about 3$\mu\textrm{m}$, TiCN coated Ti showed the highest wear resistance. However, after removing the coating layers, the wear rates of all nitrides coated Ti reverted to their normal rates of below 10,000 revolutions from Ti-disk-on-disk wear testing under the same load condition. From the results obtained, it is suggested that the insufficient depth of the 100 Kel N$\^$＋/ ion implanted zone and of the nitrides coated layers of 3$\mu\textrm{m}$ are subject to restriction when used as frictional parts of load bearing implants.

• Journal of Society of Preventive Korean Medicine
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• v.6 no.2
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• pp.66-85
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• 2002

Traditional herbal medicine is used extensively among the Korean populations, and other Asian countries employ similar therapies as well In recent years, extensive focus was laid on adulteration of the herbal medicine with heavy metals. This may be mainly due to a soil contamination by an environmental pollution. The objective of this study is to identify the contents of various heavy metals in the blood from OhJeokSan-Decoction (OD) treated-rats. For this study, 13 kinds of metals including essential and heavy metals, i.e. Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se and Zn were analyzed by a slight modification of EPA methods and the following results are obtained. ; 1. There is no significant difference between the OD-treated groups and control group in liver, kidney, bone, brain, weight, food intake. 2. The amount of each metal analyzed in the liver are as follows; Al ; $0.235{\sim}4.215mg／kg$, As ; $0.103{\sim}0.461mg／kg$, Cd ; $0.005{\sim}0.010mg／kg$, Co ; $0.017{\sim}0.046mg／kg$, Cr ; $0.137{\sim}0.403mg／kg$, Cu ; $1.736{\sim}4.827mg／kg$, Fe ; $54.472{\sim}381.447mg／kg$, Hg ; not detected, Mn ; $1.159{\sim}2.803mg／kg$, Ni ; $0.007{\sim}0.095mg／kg$, Pb ; not detected, Se ; $0.682{\sim}1.887mg／kg$, Zn ; $10.213{\sim}26.119mg／kg$, by groups, respectively. In control and other experimental group, several metal (Co, Cu, Mn, Zn, As, Cr) has a significant difference, but in experimental I and other experimental II, III, IV, V groups, there are no significant difference. 3. The amount of each metal analyzed in the kidney are as follows; Al ; $1.712{\sim}31.230mg／kg$, As ; $0.062{\sim}0.439mg／kg$, Cd ; $0.010{\sim}0.062mg／kg$, Co ; $0.000{\sim}0.101mg／kg$, Cr ; $0.125{\sim}0.636mg／kg$, Cu ; $3.385{\sim}12.502mg／kg$, Fe ; $41.148{\sim}99.709mg／kg$, Hg ; $0.000{\sim}0.270mg／kg$, Mn ; $0.433{\sim}2.301mg／kg$, Ni ; $0.000{\sim}0.221mg／kg$, Pb ; $0.000{\sim}0.584mg／kg$, Se ; $0.540{\sim}1.600mg／kg$, Zn ; $8.775{\sim}17.060mg／kg$, by groups, respectively. The concentration of Cu, Se, Cr, and Hg are variated significantly in control and other experimental group, and Cu, Se, Cd, Cr are variated significantly in experimental I and other experimental II, III, IV, V groups. 4. The amount of each metal analyzed in the bone(tibia and fibula) are as follows; Al ; $9.557{\sim}119.464mg／kg$, As ; $0.139{\sim}12.250mg／kg$, Cd ; $0.000{\sim}0.295mg／kg$, Co ; $0.022{\sim}0.243mg／kg$, Cr ; $0.239{\sim}1.999mg／kg$, Cu ; $0.000{\sim}2.291mg／kg$, Fe ; $240.249{\sim}841.956mg／kg$, Hg ; $0.000{\sim}0.983mg／kg$, Mn ; $0.214{\sim}7.353mg／kg$, Ni ; $5.473{\sim}11.453mg／kg$, Pb ; $0.000{\sim}8.502mg／kg$, Se ; $0.000{\sim}3.005mg／kg$, Zn ; $61.158{\sim}195.038mg／kg$, by groups, respectively. The concentration of Se, Cd are variated significantly in control and other experimental groups, and Se is variated significantly in experimental I and other experimental II, III, IV, V groups. 5. Exceptionally several metal concentration is increased or decreased. but there is no significant harmful difference of metal concentration in the liver, kidney and bone, from the OD-treated-rats compared to those of the control group even if higher dosage($1{\sim}8$ times dosage of person) of OD was administered. Thus, it is expected that the herbal decoction in the traditional herbal medicine would not lay any burden on the body and the heavy metal toxins would not affect our physiological system. However, other kinds of herbal treatment, such as i.v. and i.p. should be considered in terms of metal toxicity in the body since the level of certain metal.

• Economic and Environmental Geology
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• v.47 no.4
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• pp.351-362
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• 2014

In order to grasp the geological characteristics, the occurrence mode of ore body and development potential of Bophi Vum chromite mineralized zone in northwestern Myanmar, Korea Institute of Geoscience and Mineral Resources(KIGAM) and Department of Geological Survey and Mineral Exploration(DGSE) carried out joint exploration targeting on the $6km^2$ areas within the mineralized zone. Chromitites occur as a major Cr-ore body in the Bophi Vum area, and are enveloped by dunitic peridotites. As a result of geological survey, the geological map of Bophi Vum was drawn in the scale of 1:1,000, and we discovered that the chromitite ores are mainly distributed at the elevation range between 200 and 400 m. The soil geochemistry was conducted by collecting total 114 soil samples in the interval of 50 m after pitting ground surface under 0.7-1 m. Geochemical anomaly maps of Cr, Ni, Fe, and Mn were prepared by ICP-AES.