• Title/Summary/Keyword: Nanosized

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Synthesis of Monodisperse ZnO Nanoparticles Using Semi-batch Reactor and Effects of HPC Affecting Particle Size and Particle Size Distribution (반회분식 반응을 이용한 단분산 ZnO 나노 입자의 제조 및 입자의 크기와 입도 분포에 영향을 미치는 HPC의 작용)

  • Rho, Seung Yun;Kim, Ki Do;Song, Gun Yong;Kim, Hee Taik
    • Applied Chemistry for Engineering
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    • v.17 no.3
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    • pp.274-279
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    • 2006
  • To synthesize ZnO colloidal solution by a sol-gel process, zinc acetate ($C_{4}H_{6}O_{4}Zn{\cdot}2H_{2}O{\cdot}0.2\;mol$) and lithium hydroxide ($LiOH{\cdot}H_{2}O{\cdot}0.14\;mol$) in the ethanol were added to the solution containing a dispersing agent, hydroxypropyl cellulose (HPC). The nanosize and physical shape of the synthesized ZnO particles were determined by HPC acting as the dispersing agent. Nanosized ZnO particles were also obtained by a precipitation method based on zinc-2-ethylhexagonate. The precipitates were characterized by DLS, XRD, FE-SEM, and UV-vis. As the results, the ZnO colloids tend to self-assemble into a well-ordered hexagonal close-packed structure. The ZnO nanoparticles have an average diameter of nearly 40 nm with a narrow size distribution.

Pharmacopuncture of Bauhinia variegata Nanoemulsion Formulation against Diabetic Peripheral Neuropathic Pain

  • Gupta, Pushpraj S;Singh, Sunil K;Tripathi, Abhishek K
    • Journal of Pharmacopuncture
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    • v.23 no.1
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    • pp.30-36
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    • 2020
  • Objectives: The objective of the study was to prepare Bauhinia variegata loaded nanoemulsion(formulation and determine the efficacy of herbal drug formulation against diabetic peripheral neuropathic pain through acupuncture technique. Methods: Nine different ba tches of nanoemulsion (NE1 NE9) of BVN was prepared by varying the Smix ratio and the concentration of oil. BVN was characterized to determine particle size, shape, zeta potential, polydispersity index, optical transmittance, drug release profile and stora ge stability. The optimized formulation was subjected to plantar test, behavioral tests of neuropathic pain and Von Frey filament stimulation test. Diabetes was induced by intraperitoneal injection of freshly prepared solution of Streptozotocin (60 mg/kg) to the experimental rats. Animals were made diabetic divided into four groups, Group I was untreated normal control group, Group II was diabetic control group, Group III was Bauhinia variegata extract ( treated group (100 mg/kg/day, p.o) and Group IV was BVN treated groups (100 mg/kg/day, p.o) acute and chronically. Results: The prepared B. variegata loaded nanoemulsion was nanosized (124 nm), spherical, uniform and stable over the period of 180 days with no change in physiochemical properties. The bl ood glucose and body weight of animals was normalizing after four weeks of treatment that was significant with BVN in comparison to diabetic control group. The chronic administration of BVN significantly (P<0.001) decreased hind paw withdrawal latency an d attenuated mechanical allodynia as compared with diabetic rats. Conclusion: Thus, BVN may be an effective drug formulation against diabetic peripheral neuropathic pain.

Thixoforming Characteristics of Metal Matrix Composites (Phase identification of $SiC_p/AZ91HP$ Mg composite) (금속기 복합재료의 틱소포밍 특성 ($SiC_p/AZ91HP$ Mg 복합재료의 상분석을 중심으로))

  • Lee, Jung-Il;Kim, Young-Jig
    • Applied Microscopy
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    • v.29 no.3
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    • pp.281-289
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    • 1999
  • The stirred and thixoformed $SiC_p/AZ91HP$ Mg composites are studied on the basis of microstructural analysis using transmission electron microscopy (TEM). The products of interfacial reaction are identified as $Mg_2Si$, MgO and $Mg_{17}Al_{12}$ phases and the crystallized phases are found to be orthorhmbic $Al_6Mn$ and decagonal T phases. It is shown that $Mg_2Si$ and $Mg_{17}Al_{12}$ phases are found at the surface of $SiC_p$ and $Al_6Mn$ is found near interface and crystallized on the matrix. Phase identification is carried out by crystallographic work based on primitive cell volume, zero order Laue zone (ZOLZ) patterns and single convergent beam electron diffraction (CBED) patterns containing higher order Laue zone ring from a nanosized region.

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Synthesis of Spindle Shape α-FeOOH Nanoparticle from Ferrous(II) Sulfate Salt (황산 제1철을 이용한 방추형 괴타이트 나노 입자의 합성)

  • Han, Yang-Su;You, Hee-Joun;Moon, Ji-Woong;Oh, You-Keun
    • Journal of the Korean Ceramic Society
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    • v.42 no.11 s.282
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    • pp.722-728
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    • 2005
  • A wet-chemical route was utilized to obtain nanosized crystalline goethite ($\alpha$-FeOOH) particle, which was known as an oxidation catalyst in reducing carbon monoxide (CO) and dioxine during incineration. A cost-effective $FeSO_4{\cdot}7H_2O$ was used as starting raw material and a successive process of hydrolysis-oxidation was utilized as synthetic method. The effects of the initial $Fe^{2+}$ concentration, hydrolysis time and oxidation period on the crystalline phase and particle characteristics were systematically investigated by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and BET analyses. It was found that the spindle-shaped crystalline $\alpha$-FeOOH particle with the width of 70 nm and the length of 200 nm could be obtained successfully when the initial concentration of 1.5 M, hydrolysis time of 4h, and oxidation period of 10 h, respectively. In addition, it was observed that the spindle-shaped $\alpha$-FeOOH particle consisted of nano-sized primary crystallites of $30\~50\;nm$, which were de-agglomerated into individual particle and successively re­agglomerated into spherical or irregular-shaped agglomerates beyond certain periods in the hydrolysis and oxidation process.

Synthesis of Poly (lactide)-b-Poly (glycerol) (PLA-b-PG) Block Copolymer (Poly (lactide)-b-Poly (glycerol) 블록 공중합체의 중합)

  • Lee, John Hwan;Oh, Seong-Geun;Kim, Yong-Jin
    • Journal of the Society of Cosmetic Scientists of Korea
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    • v.43 no.2
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    • pp.165-174
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    • 2017
  • This study reports a synthesis of an amphiphilic linear block copolymer consisting of a hydrophobic poly (lactide) (PLA) block and a hydrophilic hyperbranched polyglycerol (hbPG) block, PLA-b-hbPG. Simple chemical modification of the hbPG block with 4-hydroxycinnamic acid (CA) led to a photo-crosslinkable block copolymer, PLA-b-hbPG-CA. Nanosized micelles of the block copolyemrs were used as drug carriers for sustainable release. The hbPG shell made of a small molecular weight hbPG block showed excellent hydrophilicity, which can minimize in vivo toxicity. The UV-crosslinked PLA-b-hbPG-CA micelles loaded with drugs colud be served as a drug delivery carrier for its biocompatibility and self-assembled structures.

Photoluminescence of Y3(Al, Ga)5O12:Ce3+ Nanoparticles by a Reverse Micelle Process

  • Kim, Min Yeong;Bae, Dong-Sik
    • Korean Journal of Materials Research
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    • v.23 no.1
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    • pp.31-34
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    • 2013
  • Trivalent cerium-ion-doped $Y_3(Al,\;Ga)_5O_{12}$ nanoparticle phosphor nanoparticles were synthesized using the reverse micelle process. The Ce doped $Y_3(Al,\;Ga)_5O_{12}$ particles were obtained from nitrate solutions dispersed in the nanosized aqueous domains of a micro emulsion consisting of cyclohexane as the oil phase and poly(oxyethylene) nonylphenyl ether (Igepal CO-520) as the non-ionic surfactant. The crystallinity, morphology, and thermal properties of the synthesized $Y_3(Al,\;Ga)_5O_{12}:Ce^{3+}$ powders were characterized by thermogravimetry-differential thermal analysis (TGA-DTA), X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), and transmission electron microscopy. The crystallinity, morphology, and chemical states of the ions were characterized; the photo-physical properties were studied by taking absorption, excitation, and emission spectra for various concentrations of cerium. The photo physical properties of the synthesized $Y_3(Al,\;Ga)_5O_{12}:Ce^{3+}$ powders were studied by taking the excitation and emission spectra for various concentrations of cerium. The average particle size of the synthesized YAG powders was below $1{\mu}m$. Excitation spectra of the $Y_3Al_5O_{12}$ and $Y_3Al_{3.97}Ga_{1.03}O_{12}$ samples were 485 nm and 475 nm, respectively. The emission spectra of the $Y_3Al_5O_{12}$ and $Y_3Al_{3.97}Ga_{1.03}O_{12}$ were around 560 nm and 545 nm, respectively. $Y_3(Al,\;Ga)_5O_{12}:Ce^{3+}$ is a red-emitting phosphor; it has a high efficiency for operation under near UV excitation, and may be a promising candidate for photonic applications.

Amorphous Vanadium Titanates as a Negative Electrode for Lithium-ion Batteries

  • Lee, Jeong Beom;Chae, Oh. B.;Chae, Seulki;Ryu, Ji Heon;Oh, Seung M.
    • Journal of Electrochemical Science and Technology
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    • v.7 no.4
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    • pp.306-315
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    • 2016
  • Amorphous vanadium titanates (aVTOs) are examined for use as a negative electrode in lithium-ion batteries. These amorphous mixed oxides are synthesized in nanosized particles (<100 nm) and flocculated to form secondary particles. The $V^{5+}$ ions in aVTO are found to occupy tetrahedral sites, whereas the $Ti^{4+}$ ions show fivefold coordination. Both are uniformly dispersed at the atomic scale in the amorphous oxide matrix, which has abundant structural defects. The first reversible capacity of an aVTO electrode ($295mAhg^{-1}$) is larger than that observed for a physically mixed electrode (1:2 $aV_2O_5$ | $aTiO_2$, $245mAhg^{-1}$). The discrepancy seems to be due to the unique four-coordinated $V^{5+}$ ions in aVTO, which either are more electron-accepting or generate more structural defects that serve as $Li^+$ storage sites. Coin-type Li/aVTO cells show a large irreversible capacity in the first cycle. When they are prepared under nitrogen (aVTO-N), the population of surface hydroxyl groups is greatly reduced. These groups irreversibly produce highly resistive inorganic compounds (LiOH and $Li_2O$), leading to increased irreversible capacity and electrode resistance. As a result, the material prepared under nitrogen shows higher Coulombic efficiency and rate capability.

Effect of Water Addition on Activity of Gold Catalysts Supported on Metal Oxide at Low Temperature CO Oxidation (일산화탄소 저온 산화에서 금속산화물에 담지된 금촉매의 활성에 미치는 수분첨가의 영향)

  • Ahn, Ho-Geun;Kim, Ki-Joong;Chung, Min-Chul
    • Korean Chemical Engineering Research
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    • v.49 no.6
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    • pp.720-725
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    • 2011
  • Gold catalysts supported on metal-oxides were prepared by co-precipitation using the various metal nitrates and chloroauric acid as precursors, and effect of water addition on the catalytic activity in CO oxidation was investigated. Among the various supported gold catalysts, Au/$Co_{3}O_{4}$ and Au/ZnO catalysts showed the excellent activity for CO oxidation. Water in the reactant gas had a negative effect on the oxidation activity over Au/$Co_{3}O_{4}$ catalysts and a positive effect on that over Au/ZnO, which means the activity depends strongly on the nature of support. It was also confirmed that no significant change in the particle size of gold was observed after reaction both in dry and wet conditions. This fact suggested that the deactivated catalyst due to a carbonate species could be regenerated by water addition in the reactant gas.

Synthesis and Characterization of Nanosized of Spinel LiMn2O4 via Sol-gel and Freeze Drying Methods

  • Seyedahmadian, Masoud;Houshyarazar, Shadi;Amirshaghaghi, Ahmad
    • Bulletin of the Korean Chemical Society
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    • v.34 no.2
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    • pp.622-628
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    • 2013
  • Nanocrystalline spinel lithium manganese oxide ($LiMn_2O_4$) powders with narrow-size-distribution, pure-phase particles, and high crystallinity with an average crystallite size of about 70 nm were synthesized at $600^{\circ}C$ for 6 h in air by freeze drying method. Spinel $LiMn_2O_4$ is also prepared by sol-gel using citric acid as a chelating agent. The influence of different parameters such as pH conditions, solvent, molar ratio of citric acid to total metal ions, calcination temperature, starting material on the structure, morphology and purity of this oxide was investigated. The results of sol-gel method show that pure $LiMn_2O_4$ with average crystallite size of about 130 nm can be produced from nitrate salts as starting materials at $800^{\circ}C$ for 6 h in air. The optimum pH and molar ratio of chelating agent to total metal ions are $4{\leq}pH{\leq}6$ and 1.0, respectively. A possible mechanism on the formation of the nanocrystallines synthesized by sol-gel was also discussed. At the end a comparison of the differences between two methods was made on the basis of x-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA) tests.

Performance Analysis of Low-level Radiation Shielding Sheet with Diamagnetic Nanoparticles

  • Cho, Jae-Hwan;Kim, Myung-Sam
    • Journal of Magnetics
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    • v.20 no.2
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    • pp.103-109
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    • 2015
  • In this study, the authors attempted to produce a medical radiation shielding fiber that can be produced at a nanosize scale and that is, unlike lead, harmless to the human body. The performance of the proposed medical radiation shielding fiber was then evaluated. First, diamagnetic bismuth oxide, an element which, among elements that have a high atomic number and density, is harmless to the human body, was selected as the shielding material. Next, 10-100 nm sized nanoparticles in powder form were prepared by ball milling the bismuth oxide ($Bi_2O_3$), the average particle size of which is $1-500{\mu}m$, for approximately 10 minutes. The manufactured bismuth oxide was formed into a colloidal solution, and the radiation shielding fabric was fabricated by curing after coating the solution on one side or both sides of the fabric. The thicknesses of the shielding sheets prepared with bismuth oxide were 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, and 1.0 mm. An experimental method was used to measure the absorbed dose and irradiation dose by using the lead equivalent test method of X-ray protection goods presented by Korean Industrial Standards; the resultant shielding rate was then calculated. From the results of this study, the X-ray shielding effect of the shielding sheet with 0.1 mm thickness was about 55.37% against 50 keV X-ray, and the X-ray shielding effect in the case of 1.0 mm thickness showed shielding characteristics of about 99.36% against 50 keV X-ray. In conclusion, it is considered that nanosized-bismuth radiation shielding fiber developed in this research will contribute to reducing the effects of primary X-ray and secondary X-ray such as when using a scattering beam at a low level exposure.