| 1. |
- Beshkova, Milena, et al.
(author)
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Sublimation epitaxy of AlN layers grown by different conditions on 4H-SiC substrates
- 2007
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In: Journal of Optoelectronics and Advanced Materials. - 1454-4164 .- 1841-7132. ; 9:1, s. 213-216
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Journal article (peer-reviewed)abstract
- Epitaxial layers of aluminium nitride were grown at temperature 2100 degrees C on 10X10 mm(2) 4H-SiC substrates via a sublimation-recondensation method in an RF heated graphite furnace. The source material was polycrystalline sintered AIN. Growths of AIN layers in vacuum and pure nitrogen at 20 mbar were compared. MA maximum growth rate of 70 mu m/h was achieved in a pure N-2 atmosphere. The surface morphology reveals the hexagonal symmetry of the seeds, suggesting an epitaxial growth. This was confirmed by High-Resolution X-Ray Diffraction. The spectra showed a strong and well defined (0002) reflection positioned at 36.04 degrees in a symmetric theta-2 theta scan for both samples. Micro-Raman spectroscopy revealed that the films had a wurtzite structure. Rutherford Backscattering Spectrometry indicated the quality with a relative chi(min) parameter 0.68.
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| 2. |
- Bih, H., et al.
(author)
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Preparation and electrical conductivity of NaF-Li2O-WO3-P2O5 glasses
- 2009
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In: Journal of Optoelectronics and Advanced Materials. - 1454-4164 .- 1841-7132. ; 3:9, s. 959-963
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Journal article (peer-reviewed)abstract
- Several studies have been reported on lithium phosphate glasses to which lithium halides and lithium sulphate have been added However, there has been no experimental results for the introduction of sodium fluoride into the lithium tungsten phosphate network How specifically this feature - mixed alkali in the presence of fluorine ion - influences ion transport in the glasses is unclear. This work concerns the investigation of ion transport behaviour of NaF containing lithium tungsten phosphate glasses in order to understand better the role of NaF in the ionic cation transport Glasses obtained in the system 0.5[x(2NaF)-(1-x)Li2O]-0.5[0.25(WO3)(2)-0.75P(2)O(5)] were investigated The glass samples have been characterised using powder X-ray diffraction (XRD), thermal analysis, density and impedance spectroscopy X-ray diffraction and thermal studies have confirmed that these glasses can be formed in the range x = 0 to 1 The mixed alkali glasses have shown higher activation energies and lower conductivities compared to single alkali doped glasses and this has been attributed to a mixed alkali influence on the electrical conduction in these systems.
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| 3. |
- Fakhar-E-Alam, M., et al.
(author)
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Anticancer effects of nanometallic oxides and their ligands with photosensitizers in osteosarcoma cells
- 2015
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In: Journal of Optoelectronics and Advanced Materials. - : NATL INST OPTOELECTRONICS. - 1454-4164 .- 1841-7132. ; 17:11-12, s. 1808-1815
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Journal article (peer-reviewed)abstract
- We studied the cytotoxic effects in Osteosarcoma (U2OS) cells to different nanosized metallic oxides e.g. zinc oxide nanowires (ZnO-NRs), manganese di-oxide nanowires (MnO2 NWs), ferric oxide nanoparticles (Fe2O3 NPs) individually and their connplexed forms with photosensitizers photofrin (R), 5-Aminolevulinic acid (5-ALA), and protoporphyrin IX (Pp IX). Cellular toxicity was assayed by cellular morphology, reactive oxygen species (ROS) detection, MTT assay under ultraviolet (UV), visible light and laser exposed conditions. Prominent cell death with above cited nanomaterials in their complexed forms with Photosensitizer was observed in labeled U2OS cells. This cell death might be due to their synergetic effect via the release of singlet oxygen species in Osteosarcoma cells showing their anticancer-cell effects.
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| 4. |
- Gherendi, M., et al.
(author)
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Super-heated fluid detectors for neutron measurements at JET
- 2008
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In: Journal of Optoelectronics and Advanced Materials. - 1454-4164 .- 1841-7132. ; 10:8, s. 2092-2094
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Journal article (peer-reviewed)abstract
- In this work we report the results of a first series of neutron measurements carried out at JET during the last experimental campaigns (C17-C19) using super-heated fluid detectors (SHFD's). The SHFD's were located in the neutron beam propagating along a collimated vertical line-of-sight, above the TOFOR neutron time-of-flight spectrometer (KM11 diagnostics). The radial distribution of the neutron fluence in the neutron beam was obtained with less than one cm spatial resolution. The neutron spectrum in the neutron beam was obtained over a broad energy range (six energy bins, from 10 keV to 20 MeV).
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| 5. |
- Kanciurzewska, Anna, et al.
(author)
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Study on Poly(3,4-ethylene dioxythiophene)-Poly(styrenesulfonate) as a plastic counter electrode in dye sensitized solar cells
- 2007
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In: Journal of Optoelectronics and Advanced Materials. - 1454-4164 .- 1841-7132. ; 9:4, s. 1052-1059
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Journal article (peer-reviewed)abstract
- Dye sensitized solar cells with PEDOT-PSS coated directly on flexible polyester substrate as counter electrode have been fabricated. The behavior of such plastic counter electrode in the presence of I/I-3 redox electrolyte has been investigated with X-ray photoelectron spectroscopy. We have found that some of iodine species are "trapped" within the PEDOT-PSS layer. The presence of I-3, I-2 and PEDOT charge transfer complexes with iodine species may block the surface of the electrode. Furthermore, the PEDOT may be further oxidized (p-doped) during cell operation, which in turn may cause overoxidation and loss of conductivity in the PEDOT-PSS film. Additionally, the interactions between PEDOT and iodine species may be enlarged because of the partial loss of PSS protective counter ion. That has resulted in decrease of PEDOT-PSS catalytic activity for reduction of I-3 to I in the redox electrolyte and has caused worse cell performance than in case of DSSC with Pt counter electrode.
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| 6. |
- Khranovskyy, Volodymyr, et al.
(author)
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Growth and characterization of ZnO nanostructured material
- 2008
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In: Journal of Optoelectronics and Advanced Materials. - 1454-4164 .- 1841-7132. ; 10:11, s. 2969-2975
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Journal article (peer-reviewed)abstract
- ZnO is a wide band gap (3.37 eV) semiconductor material with a high exciton binding energy (60 meV) at room temperature, which is a prerequisite for realization of efficient and stable optoelectronic systems. We demonstrated the APMOCVD growth of nanostructured ZnO material on Si and SiC with advanced emitting properties. The comparison of the properties of nanostructured polycrystalline layers with spatially disconnected ZnO nanocrystals clearly showed the advantage of the latter structures. Such structures distinctively luminesce in the UV range of the spectrum due to excitonic emission, while the contribution of the defect related luminescence is negligible. The significant improvement of the PL properties can be related to the decreased number of non-radiative recombination centers in the nanocrystals of high structural quality.
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| 7. |
- Lu, Hui, et al.
(author)
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Grain growth behavior, surface morphology evolution, structures, and optical properties of ZnO thin films prepared by RF reactive magnetron sputtering
- 2014
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In: Journal of Optoelectronics and Advanced Materials. - : NATL INST OPTOELECTRONICS. - 1454-4164 .- 1841-7132. ; 16:1-2, s. 170-175
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Journal article (peer-reviewed)abstract
- ZnO thin films were prepared by radio frequency (RF) reactive magnetron sputtering at varying deposition conditions. The effects of RF power (from 40 to 90 W) and substrate temperature (from 100 to 200 degrees C) on the grain growth behavior, surface morphology evolution, and the structural and optical properties of the films were investigated. Atomic force microscopy (AFM) measurements confirmed that the grain size and surface roughness depend mainly on the RF power and increase with increasing it at the initial deposition stage of 5 s, and are strongly affected by the substrate temperature and increase with increasing it at the final deposition stage of 45 min. The influence of both the deposition parameters on the surface structure of the ZnO films at different deposition stages and the mechanism concerning this influence were discussed. The X-ray diffraction (XRD) and optical absorption spectra analysis indicated that all the films deposited for 45 min are in the state of the compressive stress and exhibit polycrystalline nature with the (002) preferential orientation, and they have high optical transparency in the visible range and sharp absorption edges around the wavelength 360 nm corresponding to the ZnO exciton. With the increase of the RF power and substrate temperature, the grain size increases, the residual compressive stress relaxes, and the optical band gaps broaden. In comparison with the RF power, the substrate temperature has more evident influence on the microstructure of the ZnO thin films.
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| 8. |
- Oprea, Corneliu I., et al.
(author)
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Spin density calculations for two electron-acceptor constituents of molecular magnets : tetracyanoethylene and hexacyanobutadiene
- 2006
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In: Journal of Optoelectronics and Advanced Materials. - 1454-4164 .- 1841-7132. ; 8:1, s. 191-196
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Journal article (peer-reviewed)abstract
- We report quantum chemical calculations providing the spin density of two molecules used as building blocks for molecular magnets: tetracyanoethylene (TCNE) and hexacyanobutadiane (HCBD). Very good electron-acceptors, both molecules are used as building blocks of novel, nanostructured charge-transfer salts with magnetic properties. We investigate by means of perturbation theory (MP2) and density functional theory (DFT) the electronic structure of the neutral molecules as well as of the anionic radicals, and we discuss the roles of the various factors influencing the electron-accepting properties of these molecules. We compare and contrast the charge-acceptor and magnetic properties of both molecules, based on the correlation between their structures, electronic spectrum and spin densities.
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| 9. |
- Craciunescu, I., et al.
(author)
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New electrode materials based on functionalized polypyrrole
- 2008
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In: JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS. - 1454-4164. ; 10:9, s. 2271-2276
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Conference paper (peer-reviewed)abstract
- New functional electrode materials, based on polypyrrole, were prepared by potentiostatic electro-copolymerization of pyrrole with two different pyrrole monomers, functionalized with carboxylic group: 3-(1-pyrrolyl)-propanoic acid and 4-oxo-4(1H-pyrrole-3-yl)butanoic acid. The properties of the polymeric electrode materials depend mainly on the synthesis method, monomers ratio, reaction time, and the composition of the supporting electrolyte. The obtained materials were characterized by Fourier transform infrared spectroscopy and cyclic voltammetry measurements. The poly-(pyrrole-co-beta-(1pyrrolyl) propanoic acid) copolymer, deposited on the surface of a glassy carbon electrode, was used as anchor for covalent immobilization of Toluidine Blue (TB), by coupling its aromatic amino group (position 3) with the carboxylic groups existing on the modified electrode. The covalent binding of TB onto the functionalized electrode surface results in a stable modified glassy carbon electrode, exhibiting a better electrochemical activity than that corresponding to poly-TB, obtained by TB electropolymerization on the same electrode surface.
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| 10. |
- Holomb, R., et al.
(author)
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Localized States Model of GeS2 Glasses Based on Electronic States of GenSm Clusters Calculated by Using TD-DFT Method
- 2005
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In: Journal of Optoelectronics and Advanced Materials. - 1454-4164. ; 7:4, s. 1881-1888
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Journal article (peer-reviewed)abstract
- The first-principles calculation based on time dependent - density functional theory (TDDFT) reveals the origin of the molecular electronic structure and its connection to the localized states of the g-GeS2(T-i). The band gaps computed for GenSm clusters representing the local structures and their correlation to the experimental band gaps of g-GexS100-x together with possible model of band-tail states of g-GeS2 have been discussed. According to the observed results we propose to consider the band-gap states of g-GexS100-x as superposition of electronic states of GenSm clusters. The type and concentration of these clusters are compositionally-dependent and influenced by technological conditions used for glass preparation.
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