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Transport Properties in 2,6-Diamino Anthraquinone

100%
Khalil S., Darwish S.
Acta Physica Polonica A
|
1994
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vol. 85
|
issue 6
953-958
EN
Current density-voltage characteristics were obtained from 2,6-diamino anthraquinone samples using ohmic aluminium electrodes. Results showed that at low voltage the conduction process was ohmic, while at high voltage space-charge-limited conduction controlled by a single dominant trap level was presented. Thickness dependence measurements proved that the trapping sites were located at a discrete energy level. The transition voltage, V, between ohmic and space-charge-limited conduction was approximately proportional to the square of the sample thickness and was found to be temperature independent. The temperature dependence of ohmic and space-charge-limited current densities have been investigated. The results were interpreted in terms of extrinsic nature of ohmic conduction. Traps with density ≈ 2 × 10^{24} m^{-3} located at 0.50 ± 0.03 eV below the conduction band edge have been observed.
2
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Dielectric Properties of Isatomalononitrile

100%
Khalil S., Hassaan A.
|
EN
The paper reports dielectric measurements carried out for isatomalononitrile at different temperatures (346 to 383 K) and various frequencies (50 to 5 × 10^{5} Hz). Kramers-Kronig relations are used to ascertain the magnitude of the dc conductivity and to enhance the reliability of dielectric measurements. The analysis of the results shows that there exist certain very slow dielectric phenomena in isatomalononitrile. The frequency dependent conductivity of isatomalononitrile increases approximately linear with frequency. The frequency exponent has the value of 0.5, independent of temperature.
3
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AC Conductivity of Cobalt Phthalocyanine

81%
Abdel-Malik T., Kassem M., Aly N., Khalil S.
Acta Physica Polonica A
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1992
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vol. 81
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issue 6
675-680
EN
The dielectric properties of cobalt phthalocyanine are investigated in the frequency range 50-5×10^{5} Hz and within the temperature range 293-363 K. The frequency dependence of the AC impedance could be expressed by the complex plane of the complex impedance. Analysis of the AC conductivity reveals semiconducting features based predominantly on the hopping mechanism. The relaxation time, derived from the experimental results, shows a thermally activated process.
4
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Dielectric Behaviour of Potassium Acetylacetonate

81%
Abdel-Malik T., Kassem M., Abdel-Latif R., Khalil S.
Acta Physica Polonica A
|
1992
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vol. 81
|
issue 6
681-686
EN
The dielectric constant and the dielectric loss of potassium acetylacetonate, K(acac), are measured as a function of both temperature and frequency. A peak value is obtained at the a critical temperature T_{c} = 313 K. X-ray analysis revealed that at T_{c}, K(acac) undergoes phase transition from orthorhombic to triclinic structure. The Cole-Cole diagrams have been used to determine the molecular relaxation time τ. The temperature dependence of τ is expressed by thermally activated process. The impedance spectra in the frequency range from 50 Hz to 500 kHz plotted in the complex plane show semicircles. The conduction mechanism, below T_{c}, is predominantly operating at the surface. Above T_{c}, the conduction is proceeding in the bulk material with contribution from the surface.
5
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Assessment of in situ-Prepared Polyvinylpyrrolidone-Silver Nanocomposite for Antimicrobial Applications

71%
El Hotaby W., Sherif H., Hemdan B., Khalil W., Khalil S.
Acta Physica Polonica A
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2017
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vol. 131
|
issue 6
1554-1560
EN
Polyvinylpyrrolidone (PVP) is employed in several potential applications, relying of its special chemical and physical properties in addition to its low toxicity and biocompatibility. The aim of this work is to prepare polyvinylpyrrolidone-silver (PVP-Ag) nanocomposite with high inhibiting effect on the microbial growth and low cytotoxicity. In situ prepared small stable spherical silver nanoparticles, with narrow range particle size distribution, were obtained by easy, economical and rapid chemical reduction method. Silver ions were reduced to silver nanoparticles using low amount of sodium borohydride (NaBH₄) as a strong reducing agent. PVP-Ag nanocomposite was prepared using PVP as a stabilizing and capping agent. Formation of the spherical silver nanoparticles with mean particle size 5 nm was confirmed by ultraviolet-visible spectroscopy, high resolution transmission electron microscopy, and dynamic light scattering. The inhibiting growth effect of the nanocomposite toward Gram-positive bacteria (Staphylococcus aureus), Gram-negative bacteria (Pseudomonas aeruginosa), and yeast fungus (Candida albicans) were studied. The cytotoxicity of the nanocomposite against BJ1 normal skin fibroblast cell line was tested. Results of this work presented perfect antimicrobial activity of the PVP-Ag nanocomposite towards bacteria and fungi with low cytotoxicity, which may lead to promising applications in skin wound healing.
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