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11.
Photopyroelectric spectroscopy of Sb<Subscript>2</Subscript>O<Subscript>3</Subscript> - ZnO ceramics
A. Zakaria Z. Rizwan M. Hashim A. Halim Shaari W. Mohmood Mat Yunus 《The European physical journal. Special topics》2008,153(1):33-35
Photopyroelectric spectroscopy is used to study the
band-gap energy of the ceramic (ZnO + xSb2O3), x = 0.1 - 1.5 mol%
and the ceramic (ZnO + 0.4 mol% Bi2O3 + xSb2O3), x = 0 - 1.5 mol% sintered at isothermal temperature, 1280 °C, for 1 and 2 hours. The wavelength of incident light, modulated
at 9 Hz, is kept in the visible range and the photopyroelectric spectrum with
reference to doping level is discussed. The band-gap energy is reduced from
3.2 eV, for pure ZnO, to 2.86, 2.83 eV for the samples without
Bi2O3at 0.1 mol% of Sb2O3 for 1 and 2 hours of
sintering time, respectively. It is reduced to 2.83, 2.80 eV for the samples
with Bi2O3 at 0 mol% of Sb2O3 for 1 and 2 hours of
sintering time, respectively. The steepness factor σA which
characterizes the slop of exponential optical absorption is discussed with
reference to the doping level. The phase constitution is determined by XRD
analysis; microstructure and compositional analysis of the selected areas
are analyzed using SEM and EDX. 相似文献
12.
The free convection laminar flow about vertical axis-symmetric bodies is analysed. In order to obtain a universal solution, the analysis is carried out over a vertical cone having surface irregularity of a sinusoid form, since almost all surface geometry may be represented by Fourier series. The concentration (temperature), velocity distributions and rate of mass (heat) transfer through the electrode surface are computed. 相似文献
13.
14.
In this study, electron paramagnetic resonance of γ-irradiated single crystals of N-Trifluoroacetyl-α-amino isobutyric acid (F3Ac-Aib-OH) was investigated at room temperature and analyzed for different orientations of the crystal in the magnetic field. The paramagnetic species in N-Trifluoroacetyl-α-aminoisobutyric acid was attributed to the ?F2-R radical (R= CONHC(CH3)COOH). Hyperfine coupling constants and g value were also determined. In addition, the single crystal of F3Ac-Aib-OH was UV-irradiated and paramagnetic species formed was studied at room temperature. The effects of gamma irradiation on fluoroamino acid and stability were discussed. 相似文献
15.
16.
Kinetics of oxidation of L ‐cysteine by CoIII and FeIII complexes based on α‐ and γ‐diimine Schiff base ligands were studied in aqueous solution. Pairs of trans and cis isomers of the metal complexes were used in the studies. Kinetic measurements were performed at 25 °C and constant pH and ionic strength under pseudo‐first order condition, in which the concentration of cysteine was around two orders of magnitude greater than that of the metal complex. The observed rate constant was obtained by following the change in absorbance of the reaction mixture with time at a predetermined wavelength. The overall rate constant and order of the reaction with respect to cysteine and metal complex were determined. For both metal ions studied, the oxidation rate constant for the trans isomer was higher than that for the cis isomer. This was attributed to the contribution of the steric factor and the trans effect. The effects of substituents and the nature of the metal ion on the reaction rate are discussed. 相似文献
17.
N. A. Halim Z. A. Ibrahim A. B. Ahmad 《Journal of Thermal Analysis and Calorimetry》2010,102(3):983-988
The high potential for intercalations by water and various guest molecules is induced by the exchangeable cation inside Ca2+–Montmorillonite gallery. XRD peak for Mon at 2θ = 6.04° (d
001 = 1.462 nm) shows the structural effect on the clay gallery influenced by the intercalated water layers. Further increases
in the gallery height are observed with the intercalation of octadecyl ammonium cations in OMON (d
001 = 1.840 nm) and ENR-50 matrix chains in CENR-50 (d
001 = 1.954 nm). DSC studies on the other hand reveal the thermal behaviors of intercalated molecules that are linked to the
exchangeable cations. The endothermic of Ca2+–Montmorillonite (H
Mon = 356.3 J/g) in low temperature range (30–100 °C) indicates the removal of free water and hydrogen bonded water molecules,
while the endothermic around 150 °C is related to the induced skeletal layer of water within Ca2+–Montmorillonite. The OMON endothermic (H
OMON = 47.0 J/g, T
m = 36.94 °C) tells that cation exchange had modified the water structures and content inside the renewed clay. The intercalation
of ENR-50 chains into OMON gallery reveals two endothermic with the T
m1 and T
m2 are at 86.24 and 113.80 °C, respectively. These T
ms confirm that the alkyl chain segment on octadecyl ammonium cation occupy the OMON interlayer space. 相似文献
18.
Kapdan E Altinsoy N Karahan G Taskin H 《Isotopes in environmental and health studies》2011,47(1):93-100
Human body is exposed to ionising radiations both internally and externally by mainly high-energy cosmic ray particles incident on the earth's atmosphere and radioactive nuclides that originated in the earth's crust. The main objective of this study is to assess the health hazards due to environmental radiation sources in the city of Adapazari, one of the most important industrial cities of the country, Northwestern Turkey. For this purpose, natural radiation sources, external terrestrial radiations, cosmic radiations, and inhalation exposures have been investigated. The annual average external terrestrial radiation doses were determined as 0.08 and 0.35 mSv at outdoor and indoor atmospheres, respectively. The annual average cosmic radiation doses were found to be 0.08 and 0.05 mSv for directly ionising photon components and neutron components, respectively. The annual average inhalation exposure doses due to radon and thoron were obtained as 1.42 and 0.19 mSv, respectively, in the region. The annual average effective dose due to natural radiation sources was determined as a total of 2.35 mSv with the predetermined ingestion radiation dose. The lifetime cancer risk due to the background ionising radiations has been determined as 0.9×10(-2) for the residents of the Adapazari city, with the average lifespan of 70 years. The results of the effective doses due to background radiation sources in the region and the worldwide averages were discussed. 相似文献
19.
Our work concerns interaction spherical study of three toxic products, bromobenzene, tetrachloroethylene, and 4-hydroxy-chromene-2-one; using the Leap Frog algorithm, we calculated new values of cut-off of the box through Lennard-Jones potential parameters. This model was adapted to allow the determination of the characteristics for the SP1, SP2 and SP3 state points and was applied to study the properties for the three products by molecular dynamics. This method provides an advantage to confirm the structure–activity relationship for these compounds. We calculated the thermodynamic and structural properties for both canonical NVT and isothermal–isobaric NPT ensembles of these products. Numerical system results have been compared with both experimental data and recent investigation theoretical. Our simulation model isobaric–isothermal system gives accurate results, and comparing with the canonical system, this model agrees very well with the experimental data. We aim to demonstrate that the classical approach with a low statistical uncertainty for liquid toxic leads to data in very good agreement with experiment or other types of calculations. We obtained a good prediction of the thermodynamic properties. We hope that this model with a lower threshold to 2.5σ could be an effective starting material for studying the properties of complex systems. 相似文献
20.
W.S. Abdel Halim 《Applied Surface Science》2007,253(22):8974-8980
The adsorption of carbon monoxide at the defect-free (1 0 0), (1 1 0) and (2 1 0) five-atomic layer slab of the three oxides: MgO, CaO, and SrO has been investigated using the periodic Hartree-Fock level of ab initio theory, together with the 1 × 1 supercell model. All the calculated CO/oxide interaction energies exhibit exothermic character. The HF interaction energies increase monotonically in the order MgO < CaO < SrO. The surface morphology of adsorbate/substrate interaction is confirmed by considering relaxation energies, Mulliken population analysis, charge density contours, and electrostatic potential maps. 相似文献