Abstract Laser surface treatment of materials is one of the most effective methods of improving properties and performance of metallic articles. This technique proved its capabilities and advantages in comparison with other methods of surface treatment As an example, it has been shown that the distortion caused by this type of treament is at least one order of magnitude smaller than by that due to other techniques. Moreeover, laser beam is capable of reaching practically any point of the surface whatever it is narrow or difficult to reach by other techniques. The current work investigates the possibility of improving certain mechanical properties of both technically pure aluminum and A1-4o/oSi alloy, using ruby laser of 3 xl 05 W/cm2 power density. The surface of the investigated materials has been impregnated by SiC particles of varying size ranges, with or without firrther alloying of the surface with Titanium powder addition to the impregnated mixture. The laser treatment included coating one surface of each specimen of SiC particles by means of a binder added at a certain ratio (with or without Ti additions to the mixture). The coated surface was then subjected to the laser beam, which melted a layer I OO-150Jilll thick. Due to hydrodynamic effects the melt mixes with SiC particles and dissolves some or all of the added Ti and rapidly solidifies forming a thin layer distinct in properties from the original surface. Two groups of specimens were used in this study. The first group was treated by impregnating SiC particles of one size range with or without Ti-additions. Various numbers of laser pulses have been applied increasmg in a geometrical progression (1-2-4-8 pulses). These specimens were used for the study of the effect of varying: 1) the chemical composition of the substrate materials ;2) the number of laser pulses :and 3) the effect of Ti additions to the impregnating mixture on the microstracture and microhardness of the treated zones. The specimens of the 2nd group were coated by a square network of laser treated zones each 1.5mm in diameter. These specimens have been used to study :1) the effect of the chemical composition of the substrate material ;2) the size of the SiC particles and 3) the effect of Ti addition to the mixture on the wear perfomance of the treated specimens. Identical specimens have been used to determine the solubility of Si into the aluminum phase during the test by means of x-ray diffraction. This dissolved Si is partly responsible for the increase ID microhardness and wear resistance of the investigated specimens. The results show the positive effect of the applied treatment on the properties and preformence of technically pure AI and A-4%Si alloy. The materials microhardness within the treated zones has been increased by a factor of 2.7 and 2.4 for pure Al and Al-4%Si substrates, respectively. The microstructure of the treated zones became more homogeneous and the penetration of SiC particles into them has been increased with increasing the number of the applied laser pulses. The wear resistance of pure Al has been increased by a factor of 73.6 due to laser assisted impregnation, while that of AI-4%Si by afactor of 42.5. Wear resistance was found to increase with I) Si addition to the base metal; 2) Ti addition to the impregnated mixture, and 3) increasing the SiC particle size. This thesis is a part of a wider study that deals with surface treatment of Al and AI-Si alloys undertaken in our laboratry. Such study proved how effective the laser alloying and impregnation of such alloys in improving some of their mechanical properties which are important in industrial application, especially in internal combustion engine design.
أسماء عبد الرزاق وهرة (2002)

: Neodymium isotopes (Z=60) lie in the traditional rotational to transitional-spherical region that occurs at the range of deformed nuclei. The identity of 146−158 Neodymium nuclei have been determined in framework of Interacting Boson Model-2, a simulation program with NPBOS has been used to obtain the theoretical energy levels for Neodymium isotopes. The parameters of the best fit to the measured data are determined. The energy positive parity bands of those isotopes were calculated using (IBM-2) and then it compared with the experimental values. The mentioned isotopes ratios (E(4_1^+))/(E(2_1^+)) have calculated and also E-GOS curves (( E_γ)/I) have drawn as a function of the spin I, to classify symmetry of the nuclei. The electromagnetic transition probabilities B(E2) of these nuclei was calculated as well, where a good agreement for low lying energy states were obtained between experimental results and theoretical calculations. The results have been shown that the interested nuclei 152-158Nd have rotational characters SU (3), and O (6) symmetry is substantiated for 146-148Nd, as well as the critical point X (5) has been determined for 150Nd isotope.
D. Nasef, Najat S. Eshaftri, Ayad E. Ezwam, Suad M. Bogrin, Asma A. Elbendag, Sadiq M. El-kadi(12-2021)

A series of uniform polymer/amorphous silicon hybrid structures have been fabricated by means of solution-casting for polymer and radio frequency excited plasma enhanced chemical vapour deposition for amorphous silicon (a-Si:H). Poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) functioned as a photoactive donor, while the silicon layer acted as an acceptor. It is found that matching the hole mobility of the polymer to the electron mobility of amorphous silicon is critical to improve the photovoltaic performance from hybrid cells. A three-layer p-i-n structure of ITO/PEDOT:PSS(200 nm)/i-Si(450 nm)/n-Si(200 nm)/Al with a power conversion efficiency of 4.78% under a standard test condition was achieved. arabic 11 English 61
Adel Diyaf, Zhiqun He, John I. B. Wilson, Ying Peng(3-2014)