Results on the thermal analysis, switching characteristics and effect of heat treatment on the structure and electrical resistivity of the chalcogenide glass As25Si45Te30 are reported and discussed. From the dependence of the crystallization peak temperatures, Tp, on the heating rate, the crystallization activation energies were evaluated. For the investigated composition, the most probable mechanisms for the two crystallization phases are three- and one-dimensional crystal growth. Transformation from the glassy structure to the crystalline phase was responsible for the decrease in room-temperature resistivity and activation energy for conduction with increase of the annealing temperature

Optical absorption measurements have been made on As46Te46Ge8 amorphous films with thickness 85-125 nm. The measurements were carried on as-prepared and annealed specimens. The mechanism of the optical absorption follows the rule of non-direct transition. The optical energy gap (E0) increases with increasing the annealing temperature up to 473 K, followed by a sharp decrease with increasing the annealing temperature above the glass transition temperature. Electrical conductivity was measured in the temperature range 80-300 K. The effect of heat treatment on the activation energy (ΔE) for conduction and the density of localized states at the Fermi level N(EF) was studied. The electrical measurements show annealing-dependent conductivity and exhibit two types of conduction channels that contribute two conduction mechanisms. Transmission electron microscope (TEM) investigation indicates the separation of crystalline phases after annealing at temperatures higher than 473 K. The results were discussed on the basis of amorphous crystalline transformation

Optical absorption measurements have been made on As46Te46Ge8 amorphous films with thickness 85-125 nm. The measurements were carried on as-prepared and annealed specimens. The mechanism of the optical absorption follows the rule of non-direct transition. The optical energy gap (E0) increases with increasing the annealing temperature up to 473 K, followed by a sharp decrease with increasing the annealing temperature above the glass transition temperature. Electrical conductivity was measured in the temperature range 80-300 K. The effect of heat treatment on the activation energy (ΔE) for conduction and the density of localized states at the Fermi level N(EF) was studied. The electrical measurements show annealing-dependent conductivity and exhibit two types of conduction channels that contribute two conduction mechanisms. Transmission electron microscope (TEM) investigation indicates the separation of crystalline phases after annealing at temperatures higher than 473 K. The results were discussed on the basis of amorphous crystalline transformation

Optical absorption measurements have been made on As46Te46Ge8 amorphous films with thickness 85-125 nm. The measurements were carried on as-prepared and annealed specimens. The mechanism of the optical absorption follows the rule of non-direct transition. The optical energy gap (E0) increases with increasing the annealing temperature up to 473 K, followed by a sharp decrease with increasing the annealing temperature above the glass transition temperature. Electrical conductivity was measured in the temperature range 80-300 K. The effect of heat treatment on the activation energy (ΔE) for conduction and the density of localized states at the Fermi level N(EF) was studied. The electrical measurements show annealing-dependent conductivity and exhibit two types of conduction channels that contribute two conduction mechanisms. Transmission electron microscope (TEM) investigation indicates the separation of crystalline phases after annealing at temperatures higher than 473 K. The results were discussed on the basis of amorphous crystalline transformation

تم فى هذا البحث تحضير بعض مشتقات الأستلبين -قواعد شيف وكذلكركبات الأزو ثم اجريت القياسات اللأزمة لاختبار هذة المواد كمواد ضوئية غير خطية.

تم فى هذا البحث دراسة الأضافة الحلقية 2+2 تحت تاثير الضوء الفوق بنفسجى بين مورفلين-2-ين نيتريل والبيرى نافثينون

تم فى هذا البحث تخليق مركبات بيرازولوبيريميدين واىميدازو بيرازولوبيريمدين وكذلك مركبات بيرازولوبيريميدوثيون وذلك باجراء بعض التفاعلات على مركب 3-امينو-2-فينيل بيرازول-4-كاربوكساميد

تم فى هذا البحث تخليق مركبات بيرازولوبيريميدين واىميدازو بيرازولوبيريمدين وكذلك مركبات بيرازولوبيريميدوثيون وذلك باجراء بعض التفاعلات على مركب 3-امينو-2-فينيل بيرازول-4-كاربوكساميد

تم فى هذا البحث تخليق مركبات بيرازولوبيريميدين واىميدازو بيرازولوبيريمدين وكذلك مركبات بيرازولوبيريميدوثيون وذلك باجراء بعض التفاعلات على مركب 3-امينو-2-فينيل بيرازول-4-كاربوكساميد

Tomato fruits and seed lots were screened for the presence of Xanthomonas vesicatoria and Ralstonia solanacearum. Yellow colonies of Xanthomonas vesicatoria and white colonies of Ralstonia solanacearum were consistently isolated on yeast extract-dextrose-calcium carbonate agar medium (YDC) from diseased fruits and seed samples. This was confirmed by isolation on semiselective medium such as Tween B for Xanthomonas and triphenyltetrazolium salt (TTC) medium for Ralstonia solanacearum followed by biochemical tests. The four isolates belonging to Xanthomonas vesicatoria and Ralstonia solanacearum were used to inoculate a local tomato variety. The isolates were found to cause yellowing and wilting of 2-weeks-old seedlings by 8–14 days after inoculation and by 4 weeks all plants hadwilted and completely died. Bacteria with the same characteristics as those inoculated were reisolated from the infected plants. Uninoculated plants remained healthy.