• Steel and Composite Structures
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• 제11권1호
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• pp.59-76
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• 2011

Dynamic analysis of an embedded single-walled carbon nanotube (SWCNT) traversed by a moving nanoparticle, which is modeled as a moving load, is investigated in this study based on the nonlocal Timoshenko beam theory, including transverse shear deformation and rotary inertia. The governing equations and boundary conditions are derived by using the principle of virtual displacement. The Galerkin method and the direct integration method of Newmark are employed to find the dynamic response of the SWCNT. A detailed parametric study is conducted to study the influences of the nonlocal parameter, aspect ratio of the SWCNT, elastic medium constant and the moving load velocity on the dynamic responses of SWCNT. For comparison purpose, free vibration frequencies of the SWCNT are obtained and compared with a previously published study. Good agreement is observed. The results show that the above mentioned effects play an important role on the dynamic behaviour of the SWCNT.

• Journal of Magnetics
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• 제6권3호
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• pp.94-100
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• 2001

Fe-Co-Ni particles with an average size of 45 and 135 nm are characterized in terms of magnetic phase transformation and magnetic properties at room temperature. BCC structure of Fe-Co-Ni spherical particles can be synthesized from Fe-Co-Ni-Al-Cu precursor films by heating at 600-80$0^{\circ}C$ for the phase separation of Fe-Co rich Fe-Co-Ni particles, followed by a post heating at $600^{\circ}C$ for 5 hours. The average size of nanoparticles was directly determined by the thickness of precursor films. Exchange interactive hysteresis was observed for the nano-composite (Fe-Co-Ni)+(Fe-Ni-Al) films resulting from the short exchange interface between ferromagnetic Fe-Co-Ni particles surrounded by almost papramagnetic Ni-Al-Fe matrix. Arraying the isolated Fe-Co-Ni nano-particles in a random arrangement on $Al_2O_3$substrate the particle assembly showed a behavior of dipole interactive ferromagnetic clusters depending on their volume and inter-particle distance.

• 한국표면공학회지
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• 제47권5호
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• pp.244-251
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• 2014

In recent years, self-healing coatings have been the subject of increasing interest. The ability of such coatings to self-repair local damage caused by external factors is a major factor contributing to their attractiveness. Metals are extensively used in modern society in a range of applications from infrastructure to aircraft to consumer products. The protection of metals, primarily from corrosion has been an active area of materials science for many years. The aim of this review is the demonstration for recent progress achieved in the development of carrier-based self-healing coatings for the protection of metals. This review mainly covers the reports published after 2010. Two main types of carriers for corrosion inhibitors or healing agents-polymer capsules and porous composite inorganic nanoparticles-are described.

• Macromolecular Research
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• 제15권3호
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• pp.211-215
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• 2007

Hybrid thin film nanostructures composed of metal nanoparticles (NPs) and self-assembled polymer films with different spatial distributions of NPs were analyzed by optical waveguide spectroscopy (OWS). Specifically, the dielectric constants were calculated using effective medium theory for the incorporation of 1 vol% Au NP into the block copolymer (BCP) films having a cylindrical nanodomain morphology. Three cases were considered: uniform distribution of NPs in the film; selective distribution of NPs only in the cylindrical domains; and segregation of NPs to the center of the cylindrical domains. The optical waveguide spectra derived from the calculated dielectric constants demonstrate the feasibility of experimentally distinguishing the composite nanostructures with different inner morphologies in the hybrid metal NP-BCP nanostructures, by the measurement of the dielectric constants using OWS.

• 한국포장학회지
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• 제26권3호
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• pp.125-131
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• 2020

Carrageenan-based functional films were prepared by adding two different types of sulfur nanoparticles (SNP) synthesized from sodium thiosulfate (SNPSTS) and elemental sulfur (SNPES). The films were characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction spectroscopy (XRD), and thermal gravimetric analysis (TGA). Also, film properties such as UV-visible light transmittance, water contact angle (WCA), water vapor permeability (WVP), mechanical properties, and antibacterial activity were evaluated. SNPs were uniformly dispersed in the carrageenan matrix to form flexible films. The addition of SNP significantly increased the film properties such as water vapor barrier and surface hydrophobicity but did not affect the mechanical properties. The carrageenan/SNP composite film showed some antibacterial activity against foodborne pathogenic bacteria, L. monocytogenes and E. coli.

• Advances in concrete construction
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• 제7권1호
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• pp.51-63
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• 2019

The project focuses on the dynamic analysis of concrete beams reinforced with silica-nanoparticles under blast loading. The structure is located at two boundary conditions. The equivalent composite properties are determined using Mori-Tanak model. The structure is simulated with sinusoidal shear deformation theory. Employing nonlinear strains-displacements, stress-strain, the energy equations of beam were obtained and using Hamilton's principal, the governing equations were derived. Using differential quadrature methods (DQM) and Newmark method, the dynamic deflection of the structure is obtained. The influences of volume percent and agglomeration of silica nanoparticles, geometrical parameters of beam, boundary condition and blast load on the dynamic deflection were investigated. Results showed that with increasing volume percent of silica nanoparticles, the dynamic deflection decreases.

• Steel and Composite Structures
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• 제38권2호
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• pp.177-187
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• 2021

The effect of nanoparticle volume fraction on the elastic properties of a polymer-based nanocomposite was experimentally investigated and the obtained results were compared with various existing theoretical models. The nanocomposite was consisted of high density polyethylene (HDPE) as polymeric matrix and 0, 0.5, 1 and 1.5 wt.% multi walled carbon nanotubes (MWCNTs) prepared using twin screw extruder and injection molding technique. Nanocomposite samples were molded in injection apparatus according to ASTM-D638 standard. Therefore, in addition to morphological investigations of the samples, tensile tests at ambient temperature were performed on each sample and stress-strain plots, elastic moduli, Poisson's ratios, and strain energies of volume units were extracted from primary strain test results. Tensile test results demonstrated that 1 wt.% nanoparticles presented the best reinforcement behavior in HDPE-MWCNT nanocomposites. Due to the agglomeration of nanoparticles at above 1 wt.%, Young's modulus, yielding stress, fracture stress, and fracture energy were decreased and Poisson's ratio and failure strain were increased.

• 대한화학회지
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• 제67권6호
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• pp.415-419
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• 2023

In this study, we report the one-pot synthesis of reduced graphene oxide (rGO) containing platinum nanoparticles with catalytic activity to break down hydrogen peroxide as a peroxidase-mimicking catalyst. A single reducing agent was used to reduce graphene oxide and a platinum precursor at a moderately low temperature of 70℃. The rGO was homogeneously decorated with platinum nanoparticles. The catalytic activity of Pt-rGO was investigated for the oxidation of 3,3',5,5'- tetramethylbenzidine (TMB), a peroxidase substrate, in the presence of hydrogen peroxide. The Pt-rGO coupled with glucose oxidase was also able to detect glucose at millimolar concentrations (up to 1 mM). Our results show that the Pt-rGO composite is a promising catalyst for the detection of hydrogen peroxide. This method was also applied for the detection of glucose.

• Molecular & Cellular Toxicology
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• 제5권2호
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• pp.172-178
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• 2009

Nanoparticles are small-scale substances (<100 nm) with unique properties, complex exposure and health risk implications. Aluminum oxide ($Al_2O_3$) nanoparticles (NP) have been widely used as abrasives, wear-resistant coatings on propeller shafts of ships, to increase the specific impulse per weight of composite propellants used in solid rocket fuel and as drug delivery systems to increase solubility. However, recent studies have shown that nano-sized aluminum (10 nm in diameter) can generate adverse effects, such as pulmonary response. The cytotoxicity and genotoxicity of $Al_2O_3$ NP were investigated using the dye exclusion assay, the comet assay, and the mouse lymphoma thymidine kinase (tk$^{+/-}$) gene mutation assay (MLA). IC$_{20}$ values of $Al_2O_3$ NP in BEAS-2B cells were determined the concentration of 273.44 $\mu$g/mL and 390.63 $\mu$g/mL with and without S-9. However IC$_{20}$ values of $Al_2O_3$ NP were found nontoxic in L5178Y cells both of with and without S-9 fraction. In the comet assay, L5178Y cells and BEAS-2B cells were treated with $Al_2O_3$ NP which significantly increased 2-fold tail moment with and without S-9. Also, the mutant frequencies in the $Al_2O_3$ NP treated L5178Y cells were increased compared to the vehicle controls with S-9. The results of this study indicate that $Al_2O_3$ NP can cause primary DNA damage and cytotoxicity but not mutagenicity in cultured mammalian cells.

• 전기화학회지
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• 제15권4호
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• pp.236-241
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• 2012

일반적으로 그라파이트는 높은 결정성으로 인해 나노입자상으로 제조하기 어려우며 특히 표면에 친수성을 부여하기가 쉽지 않은 재료로 알려져 왔다. 본 연구에서는 박막 증착에 널리 활용되어 오던 펄스 레이저 어블레이션 기법을 액상에 적용하여 친수성이 부여된 그라파이트 나노입자를 합성하였다. 타겟으로는 그라파이트 로드를 사용하였으며 레이저 출력을 조절하며 액상에서 어블레이션을 실시한 결과 매우 높은 분산 안정성을 갖는 친수성 그라파이트 나노입자를 합성할 수 있었다. FT-IR 분석결과 합성된 친수성 그라파이트 나노입자는 카르복시기 및 카르보닐기 등이 나노입자의 형성과 동시에 표면에 도입된 것이 밝혀졌으며 이는 제타 포텐셜로도 확인할 수 있었다. 최종적으로 Polyethyleneglycol(PEG)과 컴포지트하여 아세톤 센서에 적용한 결과 기존의 카본 블랙 대비 우수한 감도를 나타내었다.