• Title/Summary/Keyword: $SiO_2$ nanoparticles

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Preparation of hybrid Fe3O4 nanoparticles for biomedical applications (생의학적 응용을 위한 Fe3O4 복합 나노입자의 제조)

  • Bae, Sung-Su;Nguyen, The Dung;Kim, Kyo-Seon
    • Journal of Industrial Technology
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    • v.36
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    • pp.77-81
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    • 2016
  • Superparamagnetic $Fe_3O_4$ nanoparticles with particle size from 10 to 20 nm were synthesized by coprecipitation method. Subsequently, the $Fe_3O_4$ nanoparticles were used to fabricate $Fe_3O_4/SiO_2$ core-shell nanoparticles by sol-gel method. The $Fe_3O_4/SiO_2$ nanoparticles synthesized by sol-gel method exhibit the high uniformities of particle size and shape. We also investigated the heating characteristics of $Fe_3O_4$ and $Fe_3O_4/SiO_2$ nanoparticles for biomedical applications. The $Fe_3O_4$ nanoparticles show the faster temperature increase and the higher specific loss power(SLP) value than the $Fe_3O_4/SiO_2$ nanoparticles.

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Pulse Electrodeposition of Polycrystalline Si Film in Molten CaCl2 Containing SiO2 Nanoparticles

  • Taeho Lim;Yeosol Yoon
    • Journal of Electrochemical Science and Technology
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    • v.14 no.4
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    • pp.326-332
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    • 2023
  • The high cost of Si-based solar cells remains a substantial challenge to their widespread adoption. To address this issue, it is essential to reduce the production cost of solar-grade Si, which is used as raw material. One approach to achieve this is Si electrodeposition in molten salts containing Si sources, such as SiO2. In this study, we present the pulse electrodeposition of Si in molten CaCl2 containing SiO2 nanoparticles. Theoretically, SiO2 nanoparticles with a diameter of less than 20 nm in molten CaCl2 at 850℃ have a comparable diffusion coefficient with that of ions in aqueous solutions at room temperature. However, we observed a slower-than-expected diffusion of the SiO2 nanoparticles, probably because of their tendency to aggregate in the molten CaCl2. This led to the formation of a non-uniform Si film with low current efficiency during direct current electrodeposition. We overcome this issue using pulse electrodeposition, which enabled the facile supplementation of SiO2 nanoparticles to the substrate. This approach produced a uniform and thick electrodeposited Si film. Our results demonstrate an efficient method for Si electrodeposition in molten CaCl2 containing SiO2 nanoparticles, which can contribute to a reduction in production cost of solar-grade Si.

Tissue Distribution of $SiO_2$ Nanoparticles in Mice after Oral Administration or Skin Treatment (마우스 경구 및 경피투여에 의한 $SiO_2$ 나노입자의 체내분포)

  • Park, Eun-Jeung;Park, Kwang-Sik
    • Environmental Analysis Health and Toxicology
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    • v.23 no.2
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    • pp.139-141
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    • 2008
  • Tissue distribution of $SiO_2$ nanopaprticles was investigated in mice after oral administration or skin treatment. ICR Male mice were treated with $SiO_2$ nanoparticles 2.5 g/kg/day for five consecutive days and sacrificed at 24 hours after the last administration. As results, the orally administered $SiO_2$ nanoparticels were distributed in the testis and kidney but not in lung at 24 hours after the last treatment. In case of skin treatment, $SiO_2$ nanoparticles were distributed to lung as well as testis, brain, kidney and liver. The results suggested that $SiO_2$ nanoparticles (12 nm) are easily absorbed through entero-gastric system or skin.

Lipofectamine-2000 Assisted Magnetofection to Fibroblast Cells Using Polyethyleneimine-Fe3O4@SiO2 Nanoparticles

  • Jang, Eue-Soon;Park, Kyeong-Soon
    • Bulletin of the Korean Chemical Society
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    • v.33 no.8
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    • pp.2567-2573
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    • 2012
  • We successfully synthesized $Fe_3O_4@SiO_2$ nanoparticles with ultrathin silica layer of $1.0{\pm}0.5$ nm that polyethyleneimine (PEI) with low molecular weight of 2.0-4.0 kDa was covalently conjugated with the resulting $Fe_3O_4@SiO_2$ nanoparticles by silane coupling reaction. The PEI-$Fe_3O_4@SiO_2$ nanoparticles were further used as gene delivery vector for a human fibroblast cell (IMR-90) line. Gene transfection efficiency of the PEI-$Fe_3O_4@SiO_2$ complexes did not increase remarkably after magnetofection; however, the addition of Lipofectamine 2000 significantly increased the transfection efficiency of the PEI-$Fe_3O_4@SiO_2$ complexes. We believe that the present approach could be utilized for magnetofection as alternative to $Fe_3O_4$ nanoparticles conjugated with the PEI of high molecular weight thanks to its relatively low cytotoxicity and high transfection efficiency.

Nonvolatile Memory and Photovoltaic Devices Using Nanoparticles

  • Kim, Eun Kyu;Lee, Dong Uk
    • Proceedings of the Korean Vacuum Society Conference
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    • 2013.02a
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    • pp.79-79
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    • 2013
  • Quantum-structures with nanoparticles have been attractive for various electronic and photonic devices [1,2]. In recent, nonvolatile memories such as nano-floating gate memory (NFGM) and resistance random access memory (ReRAM) have been studied using silicides, metals, and metal oxides nanoparticles [3,4]. In this study, we fabricated nonvolatile memories with silicides (WSi2, Ti2Si, V2Si) and metal-oxide (Cu2O, Fe2O3, ZnO, SnO2, In2O3 and etc.) nanoparticles embedded in polyimide matrix, and photovoltaic device also with SiC nanoparticles. The capacitance-voltageand current-voltage data showed a threshold voltage shift as a function of write/erase voltage, which implies the carrier charging and discharging into the metal-oxide nanoparticles. We have investigated also the electrical properties of ReRAM consisted with the nanoparticles embedded in ZnO, SiO2, polyimide layer on the monolayered graphene. We will discuss what the current bistability of the nanoparticle ReRAM with monolayered graphene, which occurred as a result of fully functional operation of the nonvolatile memory device. A photovoltaic device structure with nanoparticles was fabricated and its optical properties were also studied by photoluminescence and UV-Vis absorption measurements. We will discuss a feasibility of nanoparticles to application of nonvolatile memories and photovoltaic devices.

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Preparation and characterization of CdS nanoparticle on the surface of silica nanoparticles (실리카 나노입자 표면에 CdS 나노입자의 제조 및 평가)

  • Kang, Yun-Ok;Choi, Seong-Ho;Gopalan, A.;Lee, Kwang-Pill
    • Analytical Science and Technology
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    • v.20 no.5
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    • pp.413-418
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    • 2007
  • Poly(vinylpyrrolidone) stabilized cadmium sulfide (CdS) nanoparticles were loaded onto the surface of silica ($SiO_2$) nanoparticles by using ${\gamma}$-irradiation. TEM micrograph reveals the presence of ~20nm sized CdS nanoparticles on the surface of $SiO_2$ nanoparticles. XRD patterns confirm the crystalline. PL spectra of the simple PVP-stabilized CdS nanoparticle and $SiO_2$@CdS composite confirm the differences in the emission characteristics between them. Two prominent emission peaks were noted around 550 nm and 600 nm for PVP-stabilized CdS nanoparticles). The emission peaks noted for the PVP-stabilized CdS nanoparticles were found to be blue shifted for $SiO_2$@CdS composites. Besides, an additional emission peak around 450 nm was noticed for the $SiO_2$@CdS composite. The presence of CdS nanoparticles influence the emission characteristics and induce quantum confinement effect.

Synthesis and application of Pt and hybrid Pt-$SiO_2$ nanoparticles and control of particles layer thickness (Pt 나노입자와 Hybrid Pt-$SiO_2$ 나노입자의 합성과 활용 및 입자박막 제어)

  • Choi, Byung-Sang
    • The Journal of the Korea institute of electronic communication sciences
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    • v.4 no.4
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    • pp.301-305
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    • 2009
  • Pt nanoparticles with a narrow size distribution (dia. ~4 nm) were synthesized via an alcohol reduction method and used for the fabrication of hybrid Pt-$SiO_2$ nanoparticles. Also, the self-assembled monolayer of Pt nanoparticles (NPs) was studied as a charge trapping layer for non-volatile memory (NVM) applications. A metal-oxide-semiconductor (MOS) type memory device with Pt NPs exhibits a relatively large memory window. These results indicate that the self-assembled Pt NPs can be utilized for NVM devices. In addition, it was tried to show the control of thin-film thickness of hybrid Pt-$SiO_2$ nanoparticles indicating the possibility of much applications for the MOS type memory devices.

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Preparation of Fe3O4/SiO2 Core/Shell Nanoparticles with Ultrathin Silica Layer

  • Jang, Eue-Soon
    • Journal of the Korean Chemical Society
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    • v.56 no.4
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    • pp.478-483
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    • 2012
  • We successfully synthesized $Fe_3O_4/SiO_2$ nanoparticles with ultrathin silica layer of $1.0{\pm}0.5$ nm that was fine controlled by changing concentration of $Fe_3O_4$. Among various reaction conditions for silica coating, increasing concentration of $Fe_3O_4$ was more effective approach to decrease silica thickness compared to water-to-surfactant ratio control. Moreover, we found that concentration of the 1-octanol is also important factor to produce the homogeneous $Fe_3O_4/SiO_2$ nanoparticles. The present approach could be available to apply on preparation of other core/shell nanoparticles with ultrathin silica layer.

SYNTHESIS OF SILICA-COATED Au WITH Ag, Co, Cu, AND Ir BIMETALLIC RADIOISOTOPE NANOPARTICLE RADIOTRACERS

  • Jung, Jin-Hyuck;Jung, Sung-Hee;Kim, Sang-Ho;Choi, Seong-Ho
    • Nuclear Engineering and Technology
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    • v.44 no.8
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    • pp.971-976
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    • 2012
  • Silica-coated Au with Ag, Co, Cu, and Ir bimetallic radioisotope nanoparticles were synthesized by neutron irradiation, after coating $SiO_2$ onto the bimetallic particles by the sol-gel St$\ddot{o}$ber process. Bimetallic nanoparticles were synthesized by irradiating aqueous bimetallic ions at room temperature. Their shell and core diameters were recorded by TEM to be 100 - 112 nm and 20 - 50 nm, respectively. The bimetallic radioisotope nanoparticles' gamma spectra showed that they each contained two gamma-emitting nuclides. The nanoparticles could be used as radiotracers in petrochemical and refinery processes that involve temperatures that would decompose conventional organic radioactive labels.

Agglomerated SiO2 nanoparticles reinforced-concrete foundations based on higher order shear deformation theory: Vibration analysis

  • Alijani, Meysam;Bidgoli, Mahmood Rabani
    • Advances in concrete construction
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    • v.6 no.6
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    • pp.585-610
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    • 2018
  • In this study, vibration analysis of a concrete foundation-reinforced by $SiO_2$ nanoparticles resting on soil bed is investigated. The soil medium is simulated with spring constants. Furthermore, the Mori-Tanaka low is used for obtaining the material properties of nano-composite structure and considering agglomeration effects. Using third order shear deformation theory or Reddy theory, the total potential energy of system is calculated and by means of the Hamilton's principle, the coupled motion equations are obtained. Also, based an analytical method, the frequency of system is calculated. The effects of volume percent and agglomeration of $SiO_2$ nanoparticles, soil medium and geometrical parameters of structure are shown on the frequency of system. Results show that with increasing the volume percent of $SiO_2$ nanoparticles, the frequency of structure is increased.