• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.1
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• pp.19-24
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• 2009

The purpose of this study was to investigate the formation of apatite layer on two different titanium substrate treated with biomimetic method, Titanium plates were heat-treated at different temperatures of $400^{\circ}C$, $600^{\circ}C$, and $800^{\circ}C$ for 5 h in air atmosphere, And then, that plates were chemically treated with an alkali solution of 1 M sodium hydroxide (NaOH), The pre-treated titanium plates were soaked in the simulated body fluid (SBF) of Kokubo's recipe, After soaking for 7 days and 21 days in SBF, the coated layers formed on the titanium plates were characterized and compared with the morphology and chemical composition, The apatite formation was more activated on the titanium plates chemically treated with NaOH compared with the only heat-treated titanium plates.

• Journal of the Korean Ceramic Society
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• v.48 no.1
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• pp.26-33
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• 2011

The glass in the system of CaO-$SiO_2-P_2O_5$ and the corresponding glass-ceramics are prepared for bone cements and the behaviors of the hardening and hydroxyapatite formation were studied for the glass and glass-ceramic powders. The glass crystallized into apatite, $\alpha$-wollastonite and $\beta$-wollastonite depending on the glass composition when they were heat-treated at $950^{\circ}C$ for 4 h. A DCPD (dicalcium phosphate dihydrate : $CaHPO_4{\cdot}2H_2O$) was developed when the prepared glass and glass-ceramic powders were mixed with 3M-$H_3PO_4$ solution. The DCPD (Ca/P=1.0) transformed to HAp (Ca/P=1.67) when the bone cement was soaked in simulated body fluid (SBF), and this HAp formation strongly depended on the releasing capacity of $Ca^{2+}$ ions from the glass and glass-ceramic cements. The glass-ceramic bone cement containing $\alpha$-wollastonite crystals showed faster transformation of DCPD to HAp than other glass-ceramics containing $\alpha$- and $\beta$-wollastonite crystals. No hydroxyapatite was observed when the glass-ceramic bone cement containing apatite crystals (36P6C) was soaked in SBF even for 1 month, because no $Ca^{2+}$ ion can be released from the stable apatite crystals.

• Journal of Veterinary Clinics
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• v.29 no.4
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• pp.352-355
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• 2012

Hypospadias is a rare congenital malformation of the urethra reported in cattle. The urethral lumen of male indigenous Korean calf is open along the ventral aspect of the penis in the perineal region. Renal abscess and renal stone formation causing urinary tact infection has not been reported in hypospadia calves. The objective of this study was investigation for renal abscess and renal stone formation through autopsy. Histopathological examination and laboratory tests were performed. At autopsy, the pustules were formed on the right renal cortex, and the renal medulla abscess were formed on right and left part of the renal pelvis. Histopathological finding, this case was diagnosed as severe acute suppurative and necrotizing pyelonephritis, and severe chronic interstitial nephritis with fibrosis and moderate multifocal acute cystitis with edema. Milky exudate of the kidney has been identified as Actinomyces meyeri using the VITEK-2 system for identification of bacteria, and the stone has been identified as carbonate apatite using FT-IR system for quantification analysis. This case report describe the hypospadias complicated with urinary tract infection due to carbonate apatite stones and Actinomyces meyeri.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.6
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• pp.486-490
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• 2012

$La_{7.33}Bi_2(SiO_4)_6O_2$ specimens were fabricated by standard solid-state synthesis route for solid oxide electrolytes. The calcined powders exhibited uniform particles with a mean particle size of about $28{\mu}m$. The room-temperature structure of $La_{7.33}Bi_2(SiO_4)_6O_2$ specimens was analyzed as hexagonal, space group P63 or P63/m, and the unit cell volume increased with increase a sintering temperature. The specimens sintered at $1,175^{\circ}C$ showed X-ray patterns of homogeneous apatite single phase without the second phase such as $La_2Si_2O_7$ and $La_2SiO_5$. The specimen sintered at $1,175^{\circ}C$ showed the maximum sintered density of 5.49 $g/cm^3$. Increasing the sintering temperature, total conductivities increased, activation energy decreased and the values were $1.98{\times}10^{-5}Scm-1$ and 1.23 eV, respectively.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.79-79
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• 2017

Metallic biomaterials have been mainly used for the fabrication of medical devices for the replacement of hard tissue such as artificial hip joints, bone plates, and dental implants. Because they are very reliable on the viewpoint of mechanical performance. This trend is expected to continue. Especially, Ti and Ti alloys are bioinert. So, they do not chemically bond to the bone, whereas they physically bond with bone tissue. For their poor surface biocompatibility, the surface of Ti alloys has to be modified to improve the surface osteoinductivity. Recently, ceramic-like coatings on titanium, produced by plasma electrolytic oxidation (PEO), have been developed with calciumand phosphorus-enriched surfaces. A lso included the influences of coatings, which can accelerate healing and cell integration, as well as improve tribological properties. However, the adhesions of these coatings to the Ti surface need to be improved for clinical use. Particularly Silicon (Si) has been found to be essential for normal bone, cartilage growth and development. This hydroxyapatite, modified with the inclusion of small concentrations of silicon has been demonstrating to improve the osteoblast proliferation and the bone extracellular matrix production. Strontium-containing hydroxyapatite (Sr-HA) was designed as a filling material to improve the biocompatibility of bone cement. In vitro, the presence of strontium in the coating enhances osteoblast activity and differentiation, whereas it inhibits osteoclast production and proliferation. The objective of this work was to study Morphology of bone-like apatite formation on Sr and Si-doped hydroxyapatite surface of Ti-6Al-4V alloy after plasma electrolytic oxidation. Anodized alloys was prepared at 270V~300V voltages with various concentrations of Si and Sr ions. Bone-like apatite formation was carried out in SBF solution. The morphology of PEO, phase and composition of oxide surface of Ti-6Al-4V alloys were examined by FE-SEM, EDS, and XRD.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.157-157
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• 2017

Titanium and its alloys that have a good biocompatibility, corrosion resistance, and mechanical properties such as hardness and wear resistance are widely used in dental and orthopedic implant applications. They can directly connect to bone. However, they do not form a chemical bond with bone tissue. Plasma electrolytic oxidation (PEO) that combines the high voltage spark and electrochemical oxidation is a novel method to form ceramic coatings on light metals such as titanium and its alloys. This is an excellent reproducibility and economical, because the size and shape control of the nano-structure is relatively easy. Silicon (Si), manganese (Mn), and magnesium (Mg) has a useful to bone. Particularly, Si has been found to be essential for normal bone, cartilage growth and development. Manganese influences regulation of bone remodeling because its low content in body is connected with the rise of the concentration of calcium, phosphates and phosphatase out of cells. Insufficience of Mn in human body is probably contributing cause of osteoporosis. Pre-studies have shown that Mg plays very important roles in essential for normal growth and metabolism of skeletal tissue in vertebrates and can be detected as minor constituents in teeth and bone. The objective of this work was to study nucleation and growth of bone-like apatite formation on Ti-6Al-4V in solution containing Mn, Mg, and Si ions after plasma electrolytic oxidation. Anodized alloys was prepared at 270V~300V voltages. And bone-like apatite formation was carried out in SBF solution for 1, 3, 5, and 7 days. The morphologies of PEO-treated Ti-6Al-4V alloy in containing Mn, Mg, and Si ions were examined by FE-SEM, EDS, and XRD.

• Korean Journal of Materials Research
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• v.19 no.7
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• pp.362-368
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• 2009

Ti scaffolds with a three-dimensional porous structure were successfully fabricated using powder metallurgy and modified rapid prototyping (RP) process. The fabricated Ti scaffolds showed a highly porous structure with interconnected pores. The porosity and pore size of the scaffolds were in the range of 66$\sim$72% and $300\sim400\;\mu$m, respectively. The sintering of the fabricated scaffolds under the vacuum caused the Ti particles to bond to each other. The strength of the scaffolds depended on the layering patterns. The compressive strength of the scaffolds ranged from 15 MPa to 52 MPa according to the scaffolds' architecture. The alkali treatment of the fabricated scaffolds in an aqueous NaOH solution was shown to be effective in improving the bioactivity. The surface of the alkali-treated Ti scaffolds had a nano-sized fibre-like structure. The modified surface showed a good apatite forming ability. The apatite was formed on the surface of the alkali treated Ti scaffolds within 1 day. The thickness of the apatite increased when the soaking time in a simulated body fluid (SBF) solution increased. It is expected that the surface modification of Ti scaffolds by alkali treatment could be effective in forming apatites in vivo and can subsequently enhance bone formation.

• The Journal of the Petrological Society of Korea
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• v.23 no.3
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• pp.239-247
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• 2014

The (U-Th)/He dating utilizes the production of alpha particles ($^4He$ atoms) during natural radioactive decays of $^{238}U$, $^{235}U$ and $^{232}Th$. (U-Th)/He age can be determined from the abundances of the parent nuclides $^{238}U$, $^{235}U$ and $^{232}Th$ and the radiogenic $^4He$. Because helium is one of the noble gases (non-reactive) with a relatively small radius, it diffuses rapidly in many geological materials, even at low temperatures. Therefore, ingrowth of $^4He$ during radioactive decay competes with diffusive loss at elevated temperatures during the geologic time scale, determining the amount of $^4He$ existing today in natural samples. For example, He diffusion in apatite is known to be very rapid compared to that in most other minerals, causing a significant diffusive loss at ${\sim}80^{\circ}C$ or higher. At ${\sim}40^{\circ}C$, He diffusion in apatite becomes slow enough to preserve most $^4He$ in the sample. Thus, an apatite's (U-Th)/He age represents the timing when the sample passed through the temperature range of $80-40^{\circ}C$. The crustal depth corresponding to this temperature range is called a "partial retention zone." Normal closure temperatures for a typical grain size and cooling rate are ${\sim}60-70^{\circ}C$ for apatite and ${\sim}200^{\circ}C$ for zircon and titanite. Because the apatite He closure temperature is lower than that of most other thermochronometers, it can provide critical constraints on relatively recent or shallow-crustal exhumation histories.

• Applied Microscopy
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• v.40 no.3
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• pp.155-162
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• 2010

Bone is a hierarchically structured composite material which has been well studied by the materials engineering community because of its unique structure and mechanical properties. Bone is a laminated organic-inorganic composite composed of primarily hydroxyapatite, collagen and water. The main mineral that gives bone's hardness is calcium phosphate, which is also known as hydroxyapatite. Light microscopy (LM) and transmission electron microscopy (TEM) were used to study the structure of femurs from chicken and rabbit. The elemental analysis was used to search variation in the distribution of calcium, potassium and oxygen in the femur. Current investigation focused on two structural scales: micro scale (arrangement of compact bone) and nano scale (collagen fibril and apatite crystals). At micro scale, distinct difference was found in microstructures of chicken femur and rabbit femur. At nano scale, we analyzed the shape and size of apatite crystals and the arrangement of collagen fibril. Consequently, femurs of chicken and rabbit had very similar chemical property and structures at nano scale despite of their different species.

• Proceedings of the Materials Research Society of Korea Conference
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• 2008.11a
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• pp.42.1-42.1
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• 2008