• 공업화학
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• 제20권6호
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• pp.696-699
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• 2009

본 연구에서는 은 나노 입자와 탄산은(Silver Carbonate)을 이용하여 제조된 은나노/셀라이트(SN/C)와 탄산은/셀라이트(SC/C) 복합체의 대장균에 대한 항균특성을 조사하였다. SN/C와 SC/C 복합체의 특성은 주사전자현미경, X-선 회절법, 그리고 원자흡수분광법에 의해 알아보았다. SN/C와 SC/C 복합체의 대장균에 대한 최소 억제농도는 0.541과 0.344 ppm이었고 완전 사멸농도는 1.427과 1.623 ppm으로 나타났다. 상기의 결과로 SN/C와 SC/C 복합체의 대장균에 대한 항균효과를 확인할 수 있었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.476-476
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• 2011

Introduction of CNTs into a metal matrix has been considered to improve the mechanical properties of the metal matrix. However, the binding energy between metals and pristine CNTs wall is known to be so small that the interfacial slip between CNTs and the matrix occurs at a relatively low external stress. The interfacial strength between CNT and metal matrix is thus one of the key factors for successful development of the CNT/metal composites. Defective or functionalized CNT has been considered to enhance the interfacial strength of nanocomposites. In the present work, we design the various realistic hybrid structures of the single wall CNT/Cu complexes and characterize the interaction between single wall CNTs and Cu nano-particle and Cu13 cluster using first principle calculations. The characteristics of functionalized CNTs with various surface functional groups, such as -COOH, -OH, and -O interacting with Cu are investigated. We found that the binding energy can be enhanced by the surface functional group including oxygen since the oxygen atom can mediate and reinforce the interaction between carbon and Cu. These results strongly support the recent experimental work which suggested the oxygen on the interface playing an important role in the excellent mechanical properties of the CNT/Cu composite.

• 한국분말재료학회지
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• 제14권5호
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• pp.309-314
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• 2007

Zirconia powders with nano size pores and high specific surface areas were synthesized via aqueous precipitation and hydrothermal synthetic method using $ZrOCl_28H_2O$ and $NH_4OH$ under pH=11 and ambient condition. By this reaction. zirconia hydrate $(ZrO_x(OH)_{4-2x})$ was primarily synthesized and the obtained zirconia hydrate was heat treated hydrothermally using an autoclave at various temperatures under pH=11. X-ray diffraction, Scanning electron microscopy, Energy dispersive X-ray spectroscopy, FT-IR, Raman, Particle size analysis, DTA-TG, and BET techniques were used for the characterization of the powder. The synthesized zirconia showed an amorphous phase, however, the phase was transformed to the crystalline state during the hydrothermal process. The observed crystalline phase above $160^{\circ}C$ was a mixed phase of monoclinic and tetragonal zirconia. By the BET analysis, it was found that the specific surface area was ranged in $126{\sim}276m^2/g$ and the zirconia had the cylindrical shaped pores with average diameter of $2{\sim}7nm$.

• 한국세라믹학회지
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• 제39권7호
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• pp.642-648
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• 2002

본 연구에서는 TiCl$_4$를 가수분해 시켜 제조한 비정질의 titanium hydrous gel과 Ba(OH)$_2$.8$H_2O$를 출발물질로 사용하였으며, 반응용매로써 1,4-butanediol과 distilled water를 이용하여 나노 사이즈 BaTiO$_3$분말을 제조하였다. 용매로써 사용된 1,4-butanediol과 distilled water의 부피비에 따라 입자의 크기를 조절할 수 있으며, 습식화학법의 단점이었던 분말의 응집을 최소화 시킬 수 있다. 그리고 22$0^{\circ}C$의 비교적 낮은 반응온도에서 분산성이 우수하고, 입도분포가 좁은 약 50~200nm의 barium titanate 나노 분말을 제조하였다.

• 한국세라믹학회지
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• 제39권12호
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• pp.1119-1123
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• 2002

Nanostructured spinel NiZn ferrites were prepared by the sol-gel method from metal nitrate raw materials. Analyses by X-ray diffraction and scanning electron microscopy showed the average particle size of NiZn ferrite was under 50 nm. The single phase of NiZn ferrites was obtained by firing at 250${\circ}C$, resulting in nanoparticles exhibiting normal ferrimagnetic behavior. The nanostructured $Ni_{1-X}Zn_XFe_2O_4$ (x=0.0∼1.0) were found to have the cubic spinel structure of which the lattice constants ${\alpha}_2$ increases linearly from 8.339 to 8.427 ${\AA}$ with increasing Zn content x, following Vegard's law, approximately. The saturation magnetization $M_s$ was 48 emu/g for x=0.4 and decreased to 8.0 emu/g for higher Zn contents suggesting the typical ferrimagnetism in mixed spinel ferrites. Pure NiZn ferrite phase substituted by Cu was observed before using the additive but hematite phase was partially appeared at $Ni_{0.2}Zn_{0.2}Cu_{0.6}Fe_2O_4$. On the other hand, the hematite phase in this NiZn Cu ferrite was disappeared after using the additive of acethyl aceton with small amount. The saturation magnetization Ms of $Ni_{0.2}Zn_{0.8-y}Cu_yFe_2O_4$(y=0.2∼0.6) as measured was about 51 emu/g at 77K and 19 emu/g at room temperature, respectively.

• 한국세라믹학회지
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• 제43권4호
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• pp.242-246
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• 2006

[ ${\alpha}-Al_2O_3$ ] nanopowders were fabricated by the thermal decomposition and synthetic of Ammonium Aluminum Carbonate Hydroxide (AACH). Crystallite size of 5 to 8 nm were fabricated when reaction temperature of AACH was low, $8^{\circ}C$, and the highest $[NH_4{^+}][AlO(OH)_n{(SO_4){^-}}_{3-n/2}][HCO_3]$ ionic concentration to pH of the Ammonium Hydrogen Carbonate (AHC) aqueous solution was 10. The phase transformation fem $NH_4Al(SO_4)_2$, rhombohedral $(Al_2(SO_4)_3)$, amorphous-, ${\theta}-,\;{\alpha}-Al_2O_3$ was examined at each temperature according to the AACH. A Time-Temperature-Transformation (TTT) diagram for thermal decomposition in air was determined. Homogeneous, spherical nanopowders with a particle size of 70 nm were obtained by firing the 5 to 8 m crystallites, which had been synthesized from AACH at pH 10 and $8^{\circ}C,\;at\;1150^{\circ}C$ for 3 h in air.

• Macromolecular Research
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• 제15권7호
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• pp.623-632
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• 2007

Thermosensitive nanoparticles were prepared via the self-assembly of two different $poly({\varepsilon}-caprolactone)$-based block copolymers of poly(N-isopropylacrylamide)-b-$poly({\varepsilon}-caprolactone)$ (PNPCL) and poly(ethylene glycol)-b-$poly({\varepsilon}-caprolactone)$ (PEGCL). The self-aggregation and thermosensitive behaviors of the mixed nanoparticles were investigated using $^1H-NMR$, turbidimetry, differential scanning microcalorimetry (micro-DSC), dynamic light scattering (DLS), and fluorescence spectroscopy. The copolymer mixtures (mixed nanoparticles, M1-M5, with different PNPCL content) formed nano-sized self-aggregates in an aqueous environment via the intra- and/or intermolecular association of hydrophobic PCL chains. The microscopic investigation of the mixed nanoparticles showed that the critical aggregation concentration (cac), the partition equilibrium constants $(K_v)$ of pyrene, and the aggregation number of PCL chains per one hydrophobic microdomain varied in accordance with the compositions of the mixed nanoparticles. Furthermore, the PNPCL harboring mixed nanoparticles evidenced phase transition behavior, originated by coil to the globule transition of PNiPAAm block upon heating, thereby resulting in the turbidity change, endothermic heat exchange, and particle size reduction upon heating. The drug release tests showed that the formation of the thermosensitive hydrogel layer enhanced the sustained drug release patterns by functioning as an additional diffusion barrier.

• Journal of Dairy Science and Biotechnology
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• 제23권1호
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• pp.19-26
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• 2005

Nanofood can be simply defined as natural polymer particles containing functional food materials in nanoscale that are synthesized by polymerization or emulsification process. They have very uniform diameters in the range of 1 to 100nm and extensive surface areas due to the small particle size in spite of their non-porosity. Although the technique to produce nanofood has not long developing history, many works have been achieved in various fields. Nanofood has a lot of special advantages, such as functionality, diversity, applicability, etc. In case of the domestic food industries, however, the accumulation of related technique is insufficient against developed countries except used food materials. Also, it is difficult to acquire technical know-how from the developed countries that possess those technologies. We have been studied on preparing functional nanofood and developing new production processes since 1999. Last 5 years we have laid the foundation on the preparation of nanofood and now are focusing on developing new processes of nanofood and expending the field of its applications.

• 한국분말재료학회지
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• 제15권6호
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• pp.496-502
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• 2008

Aluminum nitride (AlN) powders were prepared by the chemical vapor synthesis (CVS) process in the $AlCl_{3}-NH_{3}-N_{2}$ system. Aluminum chloride ($AlCl_3$) as the starting material was gasified in the heating chamber of $300^{\circ}C$. Aluminum chloride gas transported to the furnace in $NH_{3}-N_{2}$ atmosphere at the gas flow rate of 200-400ml/min. For samples synthesized between 700 and $1200^{\circ}C$, the XRD peaks corresponding to AlN were comparatively sharp and also showed an improvement of crystallinity with increasing the reaction temperature. In additions, the average particle size of the AlN powders decreased from 250 to 40 nm, as the reaction temperature increased.

• Journal of Pharmaceutical Investigation
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• 제37권1호
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• pp.51-55
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• 2007

Solid lipid nanoparticles (SLNs) have been regarded to behave similar to the vegetable oil emulsions because emulsions of lipid melts are formed before lipid droplets being solidified to turn into SLNs. Compared to lipid emulsion, however, it has been more difficult to obtain stable SLNs and needs more extensive considerations on stabilizer and manufacturing process. In the present study, we tried to prepare phosphatidylcholine-based trymyristin (TM) SLNs using high pressure homogenization method and optimize the manufacturing variables such as homogenization pressure, number of homogenization cycles, cooling temperature, co-stabilizer and freeze-drying with cryoprotectants. Nano-sized TM particles could be Prepared using egg Phosphatidylcholine and pegylated phospholipids ($PEG_{2000}$PE) as stabilizers. Based on the optimization study, the dispersion was manufactured by homogenization under the pressure of 100 MPa for more than 5 cycles, and solidifying the intermediately formed lipid melt droplets by dipping in liquid nitrogen followed by thawing at room temperature. In addition, TM SLNs could be freeze-dried and then redispersed easily without significant particle size changes after freeze drying with 10% and 12.5% sucrose or trehalose. The TM SLNs established in this study can be used as delivery system for drugs and cosmetics.