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  • Author or Editor: M. Mahmoud x
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Artemisia herba-alba (Asso) and Artemisia monosperma (Delile) essential oils were tested against three sucking insect pests under laboratory and greenhouse conditions. These pests included Bemisia tabaci (Gennadius), Aphis gossypii (Glover) and Thrips tabaci (Lindman). Laboratory results showed that the LC50 of A. herba-alba and A. monosperma were 0.042, 0.075% for eggs and 0.074, 0.186% for immature stages of B. tabaci. Also, both oils gave a high toxicity on A. gossypii with LC50 0.023 and 0.085%. Artemisia herba-alba and A. monosperma were more toxic on T. tabaci and A. gossypii than B. tabaci in the laboratory test. In contrast T. tabaci was sensitive for both oils (LC50 0.038 and 0.011%). These oils were efficient for controlling tested insects on cucumber plants at greenhouses. This treatment caused 85.97, 82.17% reduction in the population of B. tabaci, 90.44, 87.99% for Aphis gossypii and 87.26, 84.99% for T. tabaci. Chemical analysis of A. herba-alba and A. monosperma oils detected the presence of hydrocarbon terpenes, oxygenated terpenes, hydrocarbon sesquiterpenes and oxygenated sesquiterpenes represented about 16.38%, 58.91%, 21.61%, 2.74% and 21.53%, 57.17%, 19.32%, 1.70%, of the oil content, respectively.

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Abstract  

The thermophysical properties of LiKSO4 crystals were studied around the high-temperature phase, atT c 2=943 K. A Heraeus (DSC) technique was used to measure the specific heat,c p, while the thermal conductivity,K, was measured by the linear heat flow steady-state method. The measured parameters showed an anomaly in the temperature dependence of bothc p andK. Anisotropy in the thermal conductivity coefficient was also observed in the different crystallographic axes.

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The thermal conductivity of LiKSO4 ferroelastic crystals was measured along the three principal crystallographic axes in the vicinity of its high temperature phase transition at 750 K. The data showed an anomalous behaviour in the temperature dependence of the thermal conductivity in the transition region of width of about 25 degrees. The anomaly in the phonon contribution to the conductivity was referred to the freezing-in of either optic-and/or acoustic-modes of lattice vibrations in the near vicinity of the phase transition. The results are discussed in terms of scattering mechanisms of energy carriers.

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The study includes the effect of absorbed dose on the absorption spectra of thoron solutions at different pHs and different concentrations. The effect of absorbed dose on the linear response limit and the decolouration yield (G-value) were determined. These results were used in determining the dosimetric characteristics of the dye solutions.Some of the investigations were undertaken in presence of varying concentrations of ethyl alcohol. The results helped in recommending a decolouration mechanism, and in calculating the specific bimolecular rate constant for reaction of the dye with OH radicals.

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Abstract  

This work is an investigation of the radiation stability of thoron-uranium complex. It deals mainly with the effect of absorbed dose on the absorption spectra of the complex at different complex concentrations. The radiolysis of the complex, was also investigated in presence of varying concentrations of ethanol and methanol. The decrease in absorbance at the characteristic peak as a function of absorbed dose, complex concentration, and alcohol concentration was used to calculate the G-value and the specific rate of bimolecular interaction of the complex molecule with water radiolysis products. The radiolysis mechanism was discussed in the light of the results.

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Accurate data are presented on the behaviour of the thermal conductivity K as a function of temperature for a pure Ni sample near its Curie point. Previous results on the electrical resistivity (ϱ, dϱ/dT are used to explain the temperature-dependence ofK(T). The results are analysed in terms of electron-phonon ands- d exchange interactions. The critical behaviour of the thermal resistivityW(=K−1) has also been investigated.

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The method of determining the thermal conductivity depends upon a relation between the maximum temperature (θ m) attained for a given current and potential difference (V) in a current carrying specimen. Heat is assumed to enter and leave specimen only through the surfaces through which electric current enters and leaves, other surfaces being insulated against flow of both heat and electricity. The plane ends of the rod were taken to be isothermal and equipotential surfaces held at a constant temperature.

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