| 1. |
- Andersson, Mikael, 1988
(author)
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Nanoparticle Magnetism: Superspin Glasses
- 2019
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In: Journal of Nanoscience and Nanotechnology. - : American Scientific Publishers. - 1533-4880 .- 1533-4899. ; 19:8, s. 4903-4910
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Journal article (peer-reviewed)abstract
- This article discusses the magnetic super-phase, which occurs in strongly interacting magnetic nanoparticle systems. The phase is a nanoparticle analog to the atomic magnetic spin glass phase and is therefore called a superspin glass. Experimental data for a dense maghemite nanoparticle compact is presented and it is shown that this system forms a superspin glass phase by undergoing a second order phase transition. Below its transition temperature the system exhibits non-equilibrium dynamical properties similar to those of atomic spin glasses. It was shown that it is possible to tune the transition temperature by choosing the size of the particles used to make the compact. By mixing two sizes of particles (9 and 11.5 nm) and making compacts of different relative concentration of these sizes it was shown that it is the average dipolar interaction which determines the transition temperature.
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| 2. |
- Battiston, S., et al.
(author)
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Influence of Al and Mg Addition on Thermoelectric Properties of Higher Manganese Silicides Obtained by Reactive Sintering
- 2017
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In: Journal of Nanoscience and Nanotechnology. - : American Scientific Publishers. - 1533-4880 .- 1533-4899. ; 17:3, s. 1668-1673
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Journal article (peer-reviewed)abstract
- Higher manganese silicides (HMS), represented by MnSix (x = 1.71-1.75), are promising p-type candidates for thermoelectric (TE) energy harvesting systems at intermediate temperature range. The materials are very attractive as they may replace lead based compounds due to their nontoxicity, low cost of starting materials, and high thermal and chemical stability. Dense pellets were obtained through fast reactive sintering by spark plasma sintering (SPS). The addition -or nanoinclusion, of Al and Mg permitted the figure of merit enhancement of the material obtained with this technique, reaching the highest value of 0.40 at 600 degrees C. Morphology, composition and crystal structure of the samples were characterized by electron microscopies, energy dispersive X-ray spectroscopy, and X-ray diffraction analyses, respectively.
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| 3. |
- Bora, Tanujjal, et al.
(author)
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Plasmonic Photocatalyst Design : Metal-Semiconductor Junction Affecting Photocatalytic Efficiency
- 2019
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In: Journal of Nanoscience and Nanotechnology. - : AMER SCIENTIFIC PUBLISHERS. - 1533-4880 .- 1533-4899. ; 19:1, s. 383-388
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Journal article (peer-reviewed)abstract
- Silver-zinc oxide nanorods (Ag-ZnO NRs) and gold-zinc oxide nanorods (Au-ZnO NRs) plasmonic photocatalysts were fabricated by the deposition of Ag and Au nanoparticles on ZnO NRs. The photocatalysts were studied with electron microscopy, energy dispersive spectroscopy (EDS), UV-vis optical absorption and photoluminescence spectroscopy. The effect of type of metals on the ZnO surface on its photocatalytic activity under ultra violet (UV) as well as visible light excitation are investigated and their contribution towards enhanced photo-generated charge separation in terms of the type of junction (Ohmic or Schottky) the metal forms with the semiconductor are explained.
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| 4. |
- Dispenza, Clelia, et al.
(author)
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Radiation-Engineered Functional Nanoparticles in Aqueous Systems
- 2015
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In: Journal of Nanoscience and Nanotechnology. - : American Scientific Publishers. - 1533-4880 .- 1533-4899. ; 15:5, s. 3445-3467
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Research review (peer-reviewed)abstract
- Controlled synthesis of nanoscalar and nanostructured materials enables the development of novel functional materials with fine-tuned optical, mechanical, electronic, magnetic, conductive and catalytic properties that are of use in numerous applications. These materials have also found their potential use in medicine as vehicles for drug delivery, in diagnostics or in combinations thereof. In principle, nanoparticles can be divided into two broad categories, organic and inorganic nanoparticles. For both types of nanoparticles there are numerous possible synthetic routes. Considering the large difference in nature of these materials and the elementary reactions involved in the synthetic routes, most manufacturing techniques are complex and only suitable for one type of particle. Interestingly, radiation chemistry, i.e., the use of ionizing radiation from radioisotopes and accelerators to induce nanomaterials or chemical changes in materials, has proven to be a versatile tool for controlled manufacturing of both organic and inorganic nanoparticles. The advantages of using radiation chemistry for this purpose are many, such as low energy consumption, minimal use of potentially harmful chemicals and simple production schemes. For medical applications one more advantage is that the material can be sterile as manufactured. Radiation-induced synthesis can be carried out in aqueous systems, which minimizes the use of organic solvents and the need for separation and purification of the final product. The radiation chemistry of water is well known, as are the various ways of fine-tuning the reactivity of the system towards a desired target by adding different solutes. This, in combination with the controllable and adjustable irradiation process parameters, makes the technique superior to most other chemical methods. In this review, we discuss the fundamentals of radiation chemistry and radiation-induced synthesis of nanoparticles in aqueous solutions. The impact of dose and dose rate as well as of controlled addition of various solutes on the final particle composition, size and size distribution are described in detail and discussed in terms of reaction mechanism and kinetics.
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| 5. |
- Kurtan, U., et al.
(author)
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Magnetically Recyclable Fe3O4@His@Cu Nanocatalyst for Degradation of Azo Dyes
- 2016
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In: Journal of Nanoscience and Nanotechnology. - : American Scientific Publishers. - 1533-4880 .- 1533-4899. ; 16:3, s. 2548-2556
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Journal article (peer-reviewed)abstract
- Fe3O4@His@Cu magnetic recyclable nanocatalyst (MRCs) was synthesized by reflux method using L-histidine as linker. The composition, structure and magnetic property of the product were characterized by X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), Fourier Transform infrared spectroscopy (FT-IR) and vibrating sample magnetometry (VSM). Powder XRD, FTIR and EDAX results confirmed that the as-synthesized products has Fe3O4 with spinel structure and Cu nanoparticles with moderate crystallinity without any other impurities. The surface of the Fe3O4@His nanocomposite was covered by tiny Cu nanoparticles. We examine the catalytic activity of Fe3O4@His@Cu MRCs for the degradation of two azo dyes, methyl orange (MO) and methylene blue (MB) as well as their mixture. The reusability of the nanocatalyst was good and sustained even after 3 cycles. Therefore this innovated Fe3O4@His@Cu MRCs has a potential to be used for purification of waste water.
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| 6. |
- Noroozi, Mohammad, 1979-, et al.
(author)
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A comparison of power factor in n and p-type SiGe nanowires for thermoelectric applications
- 2017
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In: Journal of Nanoscience and Nanotechnology. - : American Scientific Publishers. - 1533-4880 .- 1533-4899. ; 71:3, s. 1622-1626
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Journal article (peer-reviewed)abstract
- This work presents the thermoelectric properties of n- and p-type doped SiGe nanowires and shows the potential to generate electricity from heat difference over nanowires. The Si0.74Ge0.26 layers were grown by reduced pressure chemical vapor deposition technique on silicon on insulator and were condensed to the final Si0.53Ge0.47 layer with thickness of 52 nm. The nanowires were formed by using sidewall transfer lithography (STL) technique at a targeted width of 60 nm. A high volume of NWs is produced per wafer in a time efficient manner and with high quality using this technique. The results demonstrate high Seebeck coefficient in both n- and p-types SiGe nanowires. N-type SiGe nanowires show significantly higher Seebeck coefficient and power factor compared to p-type SiGe nanowires near room temperature. These results are promising and the devised STL technique may pave the way to apply a Si compatible process for manufacturing SiGe-based TE modules for industrial applications.
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| 7. |
- Saeid Hejazi, Mohammad, et al.
(author)
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Effect of Electrophoresis on the Efficiency of Graphite-Nano-TiO2 Modified Silica Sol-Gel Electrode
- 2015
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In: Journal of Nanoscience and Nanotechnology. - : American Scientific Publishers. - 1533-4880 .- 1533-4899. ; 15:5, s. 3405-3410
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Journal article (peer-reviewed)abstract
- Electrophoresis treatment was used to improve the function of a nano-TiO2 modified sol-gel electrode. Electrodes were prepared using TiO2 nanoparticles and fine graphite powder and then treated by electrophoresis. The developed electrode was employed for the detection of lactate dehydrogenase (LDH) by following the decrease in the immobilised lactate peak current due to its LDH-mediated enzymatic oxidation. Detection was realised using square wave voltammetry (SWV). Experiments showed that the positive and negative heads of the electrophoresis-treated electrode displayed different activities, with the positive head response being remarkably improved. Parameters affecting the electrode response, such as applied potential value, electrophoresis time and percentage of TiO2, were investigated and optimised. The improved performance was dependent on TiO2 concentration as well as electrophoresis voltage and time. The prepared sensor, under optimised conditions, displayed a detection limit of 0.0073 U/mu l for LDH.
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| 8. |
- Santarossa, Francesca, et al.
(author)
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Naturally Produced Co/CoO Nanocrystalline Magnetic Multilayers : Structure and Inverted Hysteresis
- 2016
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In: Journal of Nanoscience and Nanotechnology. - : American Scientific Publishers. - 1533-4880 .- 1533-4899. ; 16:5, s. 4960-4967
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Journal article (peer-reviewed)abstract
- Cobalt-based multilayers with excellent sequencing are grown via radiofrequency magnetron sputtering with the use of one Co target and natural oxidation. The Co layers are continuous, fully textured {111} and have the face centered cubic structure. At the end of deposition of each Co layer air is let to flow into the vacuum chamber via a fine (leak) valve. The top of Co is oxidized. The oxidized layers consist of cubic CoO crystallites. Near the film surface hexagonal Co(OH)(2) is also detected. Magneto-optical Kerr effect hysteresis loops show in-plane magnetized films. The magnetic saturation field in the out-of-plane measurements is large exceeding 12 kOe. This observation supports indirectly the fact that Co is face centered cubic; if it was c-axis textured hexagonal the magnetocrystalline anisotropy would be large resulting in smaller values of the saturation field. As the Co-layer thickness decreases the in-plane loops show reduced remanence, slow approach to magnetic saturation and the out-of-plane loops show inverted hysteresis and/or crossing loop features with sizeable remanence. The effects are discussed with respect to the enhanced orbital magnetic moment of Co and the antiferromagnetic coupling between Co spins at the Co/CoO interface.
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| 9. |
- Saravanan, Thulasingam, et al.
(author)
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Synthesis, Optical and Electrochemical Properties of Y2O3 Nanoparticles Prepared by Co-Precipitation Method
- 2015
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In: Journal of Nanoscience and Nanotechnology. - : American Scientific Publishers. - 1533-4880 .- 1533-4899. ; 15:6, s. 4353-4357
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Journal article (peer-reviewed)abstract
- Y2O3 nanoparticles were synthesized by co-precipitation route using yttrium nitrate hexahydrate and ammonium hydroxide as precursors. The prepared sample was calcined at 500 degrees C and subjected to various characterization studies like thermal analysis (TG/DTA), X-ray diffraction (XRD), transmission electron microscope (TEM), UV-visible (UV-Vis) and photoluminescence (PL) spectroscopy. The XRD pattern showed the cubic fluorite structure of Y2O3 without any impurity peaks, revealing high purity of the prepared sample. TEM images revealed that the calcined Y2O3 nanoparticles consist of spherical-like morphology with an average particle size of 12 nm. The absorption spectrum of calcined samples shows blue-shift compared to the as-prepared sample, which was further confirmed by PL studies. The possible formation mechanism of Y2O3 nanoparticles has been discussed based on the experimental results. Electrochemical behavior of Y2O3 nanoparticles was studied by cyclic voltammetry to assess their suitability for supercapacitor applications.
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| 10. |
- Shukla, Sudheesh K., et al.
(author)
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Cholesterol Oxidase Functionalised Polyaniline/Carbon Nanotube Hybrids for an Amperometric Biosensor
- 2015
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In: Journal of Nanoscience and Nanotechnology. - : American Scientific Publishers. - 1533-4880 .- 1533-4899. ; 15:5, s. 3373-3377
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Journal article (peer-reviewed)abstract
- Functional carbon nanotubes (CNT) have attracted much attention for analytical and biomedical applications. This paper describes the fabrication of a cholesterol oxidase (ChOx) immobilised polyaniline (PANI)/CNT composite electrode for the amperometric detection of cholesterol. The prepared ChOx/PANI/CNT/Au bioelectrode bound ChOx via the available functionalties of PANI (-NH2) and CNT (-COOH). Moreover, the CNT creates a network inside the matrix that strengthens the mechanical property of the bioelectrode. The multifunctional matrix is presumed to provide a 3D-mesoporous surface, which substantially enhances enzyme activity. The linear range of the biosensor for cholesterol oleate was 30-280 mu M with a response time of 10 sec.
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