Nanomateriala Characterization Research Papers - Academia.edu (original) (raw)

The paper provides an overview of tribological properties of nanocomposites with aluminium matrix. Nanocomposites represent a new generation of composite materials with better properties than conventional composite materials. The paper presents and explains the most common methods of nanocomposites production. In addition, the overview of tribological properties is presented through the equipment used for testing; amount, size and type of reinforcement; matrix material and manufacturing process; and test conditions.

- by and +3
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- Engineering, Materials Engineering, Mechanical Engineering, Materials Science

Heterogeneous photocatalysis is a promising technology especially for environmental remediation. Despite more than a decade of worldwide research in developing photocatalytic efficiency improving techniques, many questions regarding the large scale application of photocatalytic reactors still remain unanswered. Recently, improving the photocatalytic efficiency has gained scientific attention because it might lead to more economical and robust photocatalytic operation for environmental remediation. In this review, fundamental and comprehensive assessments of the photocatalytic concepts and their applications for environmental remediation are reviewed. The existing challenges and strategies to improve the photocatalytic efficiency are discussed. Further, recent developments and future research prospects on photocatalytic systems for environmental applications are also addressed.

In this study, pure ZnO, CeO2 and ZnO/CeO2 nanocomposites were synthesized using a thermal decomposition method and subsequently characterized using different standard techniques. High-resolution X-ray photoelectron spectroscopy measurements confirmed the oxidation states and presence of Zn2+ , Ce4+ , Ce3+ and different bonded oxygen species in the nanocomposites. The prepared pure ZnO and CeO2 as well as the ZnO/CeO2 nanocomposites with various proportions of ZnO and CeO2 were tested for photocatalytic degradation of methyl orange, methylene blue and phenol under visible-light irradiation. The optimized and highly efficient ZnO/CeO2 (90:10) nanocomposite exhibited enhanced photocatalytic degradation performance for the degradation of methyl orange, methylene blue, and phenol as well as industrial textile effluent compared to ZnO, CeO2 and the other investigated nanocomposites. Moreover, the recycling results demonstrate that the ZnO/CeO2 (90:10) nanocomposite exhibited good stability and long-term durability. Furthermore, the prepared ZnO/CeO2 nanocomposites were used for the electrochemical detection of uric acid and ascorbic acid. The ZnO/CeO2 (90:10) nanocomposite also demonstrated the best detection, sensitivity and performance among the investigated materials in this application. These findings suggest that the synthesized ZnO/CeO2 (90:10) nanocomposite could be effectively used in various applications.

- by Prof. Dr. Mohammad Mansoob Khan and +2
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- Nanomaterials Characterization, Nanomateriala Characterization, Nanocomposites, Nanomaterials
- by sudhanshu pati
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- Materials Science, Crystallography, Synthesis of nanoparticles, Biomaterials

In this work, room temperature oxidation of GaAs was investigated using ion beam oxidation (mO). In lBO, an ion beam is used to introduce oxygen athermally into the substrate, in this case GaAs. GaAs bonds are broken upon collision with the ions, making gallium and arsenic atoms readily available to react with the oxygen species. Ion beam oxidation of GaAs at room temperature was studied as a function ofoxygen ion energy between 500 and is keY. The ion beam oxidized GaAs was characterized in situ by Auger electron spectroscopy (AES) and ex situ with x-ray photoelectron spectroscopy (XPS) for accurate determination of the film chemical composition. Below 1 keY, a thin oxide film is formed: it is composed of Ga20 3 and AS20 3 with almost no metallic arsenic, and presents insulating properties.
As the ion energy increases, preferential sputtering of As and decomposition of AS203 increase and prevent formation of an
insulating film. No damage was detected by Rutherford backscattering spectrometry (RES) combined with ion channeling, in the substrate subjected to IBO below 1 keV.""

Using ion beam modification, films composed of synthesized
‘‘interphases’’ of ordered silica on OH-passivated (1 X 1) Si(100) underwent surface electro-chemical changes quantified by surface free energy via Sessile drop method and contact angle analysis using Young’s equation and Van Oss theory. IBMM caused the surface free energies initially ranging from 26.0 mJ/m2 to 57.3 mJ/m2 to converge to 43.1–45.4 mJ/m2 for various passivated and as-received wafer samples alike. Although TMAFM also identified topographic changes, these changes did not correlate to the change of surface free energies. Ion beam modification of the ordered silica film on Si(100) surface is analyzed using 3.045 MeV 16O(a, a)16O nuclear resonance scattering (NRS) in conjunction with channeling in (1 1 1) direction, which demonstrated the convergence of the partially ordered oxygen to amorphous at about 55 microCoulombs/mm2 He++ flux. Additionally, Si surface peak channeling in (1 0 0) and (1 1 1) directions also experienced an uptrend in areal density as incident ion flux increased, while the rotating random Si signal height remains stable, showing a disruption in the surface order during IBMM.

- by B.J. Wilkens and +1
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- Microelectronics And Semiconductor Engineering, Engineering Physics, Materials Engineering, Physics

In this work, we describe the synthesis of new Mixed Periodic Mesoporous Organosilica Nanoparticles (MPMO NPs), combining the co-condensation of a tetra-trialkoxysilylated two-photon photosensitizer with bis-(triethoxysilyl)phenylene or ethylene. Novel gold core-MPMO shell systems are also described. The MPMO NPs are analyzed and characterized by multiple techniques, and are very efficient for anti-cancer drug delivery combined with two-photon therapy in MCF-7 breast cancer cells, leading down to 76% cancer cell death. MPMO NPs are thus very promising for nanomedicine applications.

- by Jonas G Croissant and +1
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- Materials Engineering, Materials Science, Synthesis of nanoparticles, Material Culture Studies

Particle-Induced X-ray Emission (PIXE) analysis was employed to characterize Hydroxypropyl Methylcellulose (HPMC) polymer film via depth profiling on silicon-based substrates, and compared with Rutherford Backscattering Spectrometry (RBS) results. We utilize the concept that α particle incident energy loss by the polymer film affects the α particle penetration depth into the substrate, and can thus find the areal density of the film by computing the amount of energy loss via comparing the yield of X-ray emitted from a substrate element with and without the polymer film. It is demonstrated in this paper that this method and RBS measurements both yield comparable results for areal densities ranging from 1018 to several 1019 atom/cm2. A collection of techniques including PIXE, RBS, Tapping Mode Atomic Force Microscopy (TMAFM), and Sessile Drop contact angle method were used to compute surface free energy, analyze surface topography and roughness parameters, determine surface composition depth profiling, and to predict the water affinity and condensation behaviors of silicates, phosphosilicates, and other compounds used for high impact resistance vision ware coatings. The visor surface under study is slightly hydrophilic, with root mean square of surface roughness on the order of one nm, and surface wavelength between 200 and 300 nm. Water condensation is manifests itself under sports conditions with raised temperature and humidity. Water condensation can be controlled on such surfaces via polymers adsorption. HPMC polymer surface composition is previously determined via 4.265 MeV 12C(α, α) 12C , 3.045 MeV 16O(α, α)16O nuclear resonance analysis (NRA), and 2.8 MeV elastic recoil detection (ERD) of hydrogen1, and combined with PIXE depth profiling technique as detailed in this work to support the analysis of the surface water affinity and topography and therefore control condensation behavior2. HPMC film between 1018 and 1019 atom/cm2 is found to effectively alter the water condensation pattern and prevents fogging by forming a wetting layer during condensation.

- by CLARIZZA WATSON and +2
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- Materials Engineering, Polymer Engineering, Materials Science, Pharmacy

Different techniques have been employed to produce chitosan nanoparticles; thus, suitable alternatives and easy-handling production methods are highly desired. We used a tank reactor with baffles and mechanical stirring with Cowles impellers that can feasibly be up-scaled and allows for the production of homogenous chitosan nanoparticles. First, we explored the effects of temperature on the produc- tion of chitosan (CHI)/pentasodium tripolyphosphate (TPP) nanoparticles. We compared the effect of gradual temperature decrease between 40 to 55◦C with the effect of isothermal processes (25, 45 and 55◦C). CHI/TPP nanoparticles produced by the gradual temperature decrease technique had polydis- persity indices (PDIs) that were significantly smaller than the nanoparticles produced by isothermal processes. To further control the production process, we employed an experimental design to determine the effects of CHI and TPP concentrations and CHI/TPP mass ratios in the gradual temperature decrease technique. Under all conditions, the sizes of the CHI/TPP nanoparticles were on the nanoscale. Gene deliv- ery capacities of the nanoparticles were evaluated; the plasmid pEGFP-N1 was incorporated (10 and 40% of the chitosan weight) into the nanoparticles and incubated with 293A cells. The in vitro transfection efficiencies were evaluated over 120 h and indicated sustained gene delivery at 10% pDNA. The poly- plexes demonstrated some cytotoxicity after 120 h. These findings will contribute to the development of processes for generating CHI/TPP nanoparticles for gene delivery applications.

- by John Philip
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- Engineering, Materials Science, Crystallography, Synthesis of nanoparticles

A two-photon photosensitizer with four triethoxysilyl groups is synthesized through the click reaction. This photosensitizer allows the design of bridged silsesquioxane (BS) nanoparticles through a sol-gel process; moreover, gold core BS shells or BS nanoparticles decorated with gold nanospheres are synthesized. An enhancement of the two-photon properties is noted with gold and the nanoparticles are efficient for two-photon imaging and two-photon photodynamic therapy of cancer cells.