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  • Author or Editor: E. Mostafa x
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The mechanisms by which Azolla caroliniana respond to salt stress in absence and presence of nitrate is investigated. Screening of amino acid and differential display is used to compare overall differences in gene expression between salinity-stressed and unstressed Azolla caroliniana by quantitative reverse transcriptase polymerase chain reaction (RT-PC R). Results showed that under saline conditions, aspartic acid, glutamic acid, alanine and leucine were the amino acids found to be abundant in Azolla caroliniana, accounting for 11.26%, 8.66%, 9.43%, and 12.36%, respectively. Following salinity stress, a decrease in free glutamate concomitant with a parallel decrease in free proline was indeed evident. Interaction between nitrate and salinity stress increased proline content significantly. By screening a cDNA library, we have identified protein products by homology with known proteins. The RNA transcripts encoding protein influencing secondary metabolites and vacuolar Na+/H+ antiporter that facilitate the transport system. The databasematched under interaction of nitrate and 50 mM NaCl were associated with wall biosynthesis, disease resistance, metabolite transport and protein regulator, other gene for metabolism of steroids and secondary transport. Results obtained from this research could represent a key step in understanding the molecular mechanism of salt tolerance of Azolla caroliniana in the presence and absence of nitrate.

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This work aims in studying the temperature dependence of the thermal properties (thermal diffusivity, k, specific heat, C p and thermal conductivity, ) of some basalt group samples, collected from different regions in the eastern desert of Egypt. The thermal properties of these samples were measured in the temperature range from r.t. to 900 K. The average values of the thermal conductivity of these investigated samples lie in the range from 0.4·10–3 to 2.01·10–3 cal cm–1 s–1 K–1. This means that these samples are considered as thermal insulating materials. The thermogravimetric analysis (TG) confirmed that these investigated samples are dry rocks. X-ray fluorescence (XRF) and X-ray diffraction (XRD) confirmed that these rock samples have a crystalline phase, the peaks of XRD have a small change in their location as a result of heat treatment. This behaviour was attributed to the oxidation and firing of some minerals after the heat treatment.

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Factors affecting the cellulase production of Aspergillus niger using sugar cane bagasse as carbon source were investigated. The highest enzyme activities were obtained, when the culture medium was supplemented with 0.133% tryptone as nitrogen source. The rate of cellulase production was considerably increased when 0.5% Tween 60 was added to the production medium. For FPA and b-glucosidase production pH 5.0, while for CMC-ase pH 5.5 was found to be optimal. The highest cellulase activities were obtained at 30 °C and 300 r.p.m. The highest saccharification degree was achieved, when alkali treated rice straw was used as substrate. The main objective of the present study was to examine the possibilities of lactic acid production from alkali treated rice straw using simultaneous saccharification and fermentation technique with T. koningii cellulases and L. delbrueckii. The highest conversion of cellulose was obtained using 6% alkaline treated rice straw supplemented with 1.2 mg enzyme/g substrate at pH 4.8 and 45 °C.

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A physical approach is described for instrumental multielement activation analysis with whole neutron spectrum (without Cd-cover) using the monostandard (single comparator) method. To test the capabiliteries of this method, 15 samples representing different Egyptian granite rocks were analyzed. As many as 21 trace elements beside Fe, K and Na were determined. Calculation of the experimental data has been done using the Gamma-Monostandard Analysis program with the Commodore Computer available at the Institute of Radiochemistry at Garching near München. The accuracy of the method for nondestructive multielement analysis agrees within 3% with the relative method using multielement standards.

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A method is described for epithermal neutron activation analysis of 17 elements in granite rock samples using a single standard. Gold has been used as a single comparator due to its relatively high resonance integral value (I0=400 barn). In addition, it is preferable to Co in order to obtain a large epithermal activation in a short irradiation. The method of calculation is simple and rapid and can be done using a small calculator. Epithermal activation is able to overcome the difficulty arising from changing irradiation position as well as increasing the number of determinable elements by eliminating the interference from undesired isotopes which have relatively high thermal cross section values ( 0), when reactor neutron flux is used. The coupling of epithermal activation with the monostandard method has the advantage of using a small Cd-cover which overcomes most of the difficulties arising in the relative method with large volume cadmium filters.

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The neutron capture gamma-ray spectroscopy facility assembled at the Institute of Radiochemistry, KfK (for analytical purposes) using a252Cf neutron source with a strength of 6·107 n/s, has been used to check its applicability and sensitivity for quantitative analyses of ores. The analysis of Sm, Cd and Mn in phosphate and monazite rock samples has been carried out. The results from this study show a variation of about 25% from the values determined by RNAA method. This discrepancy could be mainly due to the low signal-to-background ratio observed which is caused by (i) scattering of the source gammarays by the target, and (ii) interference from the 2223.1 keV neutron capture hydrogen gamma-rays produced by the moderated materials and from their compton scattering in the detector. To overcome these difficulties we suggest to introduce a 2.5 cm thick polyethylene sheet between the detector6Li-cap shielding and the target as well as to increase the detection solid angle. Also the strength of the252Cf neutron source should be increased by an order of magnitude and the neutron beam should be collimated to obtain the optimal thermal neutron flux with a low level of252Cf gamma-rays. This can be achieved by setting up between the neutron source and the target a conical polyethylene collimator with a thickness of 10 cm containing a 1 cm thick lead sheet.

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