ABSTRACT:Web-based forum is an application through the internet to facilitate the process of discussions and exchange of ideas. It is also referred to as online forums, message boards, discussion groups, and discussion forums. Youth can play a role in shaping their societies of immense diversity through the means of communication and participation, and sharing ideas. Therefore, this study leads to develop a web-based forum application to help young people express themselves and their needs, and desires. The requirements of the webbased application were identified from the students in UUM who are in the similar age group, design the application, and a prototype to implement the design. ---------------------------------------------------------------------

In this paper SiC particle reinforce aluminum metal matrix composite welded using high power continuous laser. Microstructure of laser beam welded SiC/Al MMC is characterized as functions of laser processing parameters. Results show that sound weld with little pores can be produced by laser beam welding, while aluminum carbide is formed in the weld. The size and the volume fraction of aluminum carbide are proportional to the laser power density. direction of shielding gas flow has significant effect on weld quality and weld microstructure.

The present study was performed to evaluate the anti-schistosomal activity of the medicinal plant ginger Zingiber officinale. Mice were individually infected with 100 Schistosoma mansoni cercariae. Four weeks post-infection, mice were orally treated with 1200 mg/kg of ginger for ten consecutive days. After the last dose all animals were sacrificed to evaluate the efficacy of ginger in treatment of the infection. The results obtained showed moderate reduction of 16.5% in the worm burden compared with control infected animals. The liver egg count showed a marked reduction of 53.8%. Ginger treatment showed a significant reduction in the size of liver granuloma where a percentage reduction of 66.35 was observed. Ginger treatment was slightly reflected on the liver function at such rate of infection, where an improvement in serum arginase activity was recorded, while no appreciable improvement in hepatic ALT and AST activities, albumin and creatinine contents. In conclusion Z. officinale displayed some degree of anti-schistosomal activity through reducing of the S. mansoni eggs output and the liver granuloma size.

تمت إضافة ثلاثة أنواع نباتية للفلورا الليبية هي Ruta montana + Pimpinella cretica + plantago bellardii

تمت إضافة ثلاثة أنواع نباتية للفلورا الليبية هي Lactuca saligna + Sanguisorba minor

The use of computers for handling image data in the healthcare is growing The amount of data produced by modem image generating techniques, such as Computed Tomography (CT) and Magnetic Resonance (MR), is vast. The amount of data might be a problem from a storage point of view or when the data is sent over a network. To overcome these problems data compression techniques adapted to these applications are needed Many classes of images contain some spatial regions which are more important than other regions. Compression methods which are capable of achieving higher reconstruction quality of important parts of the image have been implemented For medical images, only a small portion of the image might be diagnostically useful but the cost of wrong interpretation is high. Algorithms which deliver lossless compression within the regions of interest (ROJ), and lossy compression elsewhere in the image, might be the key to providing efficient and accurate image coding to the medical community. In this thesis both of compression techniques (lossy and lossless) of medical images using the JPEG algorithm (DCT), will be discussed.

    SiC particle reinforced aluminum metal matrix composites (SiCp/Al MMCs) are finding increasing applications in aerospace, automotive and microelectronic industries because of their excellent combination of high specific strength, high specific toughness, low coefficient of expansion and excellent wear resistance. However the addition of totally dissimilar reinforcements into the aluminum matrix and the great different in electrochemical properties between the aluminum metal matrix and the SiC reinforcement deteriorate the corrosion resistance and make the SiCp/6061Al MMC prone to corrosion attacks especially when servicing under electrochemical corrosive environments.

     In this dissertation, laser surface melting, laser surface alloying with Ni-Cr-B alloy powders and laser cladding with Cu-Sn-Pb-Zn bronze powders were utilized to improve the corrosion resistance of P/M SiC particles reinforced metal matrix composite (P/M SiCp/6061Al MMC) by producing corrosion resistant surface layers or metallurgical coatings with rapidly solidified and effectively refined microstructure. The microstructure of the laser surface melted, laser surface alloyed and laser clad corrosion-resistant modified surface layers or coatings were characterized by OM, SEM, XRD as functions of laser surface processing parameters and contents of alloying elements. The hardness distribution along the laser surface modified coatings’ depth direction was tested using microhardness tester. The electrochemical corrosion resistance of laser surface melted, laser surface alloyed and the laser clad SiCp/6061Al MMC were evaluated under direct current anodic polarization electrochemical corrosion test conditions in NaCl water solutions and H₂SO₄ water solutions as functions of laser processing parameters and corrosion test conditions.

Results show that:

(1) During laser surface melting of SiCp/6061Al MMC with high power CO₂ laser beam, the SiC particles are completely dissolved and the laser surface melted layer has a rapidly solidified, homogeneous and refined microstructure consisting of aluminum silicon carbide Al₄SiC₄ aluminum carbide Al₄C₃ as well as crystalline silicon particles evenly distributed in the aluminum matrix. The microstructure as well as size and volume fraction of the newly produced phases in the laser surface melted layer on substrate of SiCp/6061Al MMC depend strongly on the laser processing parameters especially the laser linear energy density. Both the hardness and corrosion resistance of SiCp/6061Al MMC under direct current anodic polarization electrochemical corrosion test conditions in 0.1M NaCl water solutions are slightly enhanced after the laser surface melting treatment.

(2) Laser surface alloying of SiCp/6061Al MMC with Ni-Cr-B alloying powders leads to the production of rapidly solidified corrosion resistant surface layers having homogeneous and refined microstructure. The laser surface alloyed SiCp/6061Al MC is composed of fine rapidly solidified nickel aluminides of Al₃Ni_2, Al₃Ni and AlNi, and chromium borides of d-CrB and Cr₂B evenly distributed in the nickel solid solution. Microstructure of the laser surface alloyed layers is strongly dependent on the laser processing parameters and the chemical composition especially boron content of the Ni-Cr-B alloying powders. The laser surface alloyed SiCp/6061Al MMC has high hardness and excellent corrosion resistance to electrochemical corrosion under direct current anodic polarization electrochemical corrosion test conditions in NaCl water solutions.

(3) By laser cladding of SiCp/6061Al MMC with Cu-6Sn-6Pb-3Zn bronze powders a rapidly solidified homogeneous dendritic bronze coating is produced on substrate of SiCp/6061Al MMC with refined microstructure consisting of fine copper-base solid solution and the interdendritic Cu₃₁Sn₈ intermetallic particles_. The laser clad corrosion resistant coating is bonded to the substrate of SiCp/6061Al MMC, metallurgically. The corrosion resistance of SiCp/6061Al MMC to the electrochemical corrosion under direct current anodic polarization electrochemical test conditions in NaCl water solutions is significantly improved after laser cladding treatment with the bronze powders.

(4) Laser surface melting, laser surface alloying and laser cladding are demonstrated to be among the promising surface modification methods for enhancing corrosion resistance of SiCp/6061Al MMC.

Keywords:  SiCp/Al Metal Matrix Composites, Laser Surface Melting, Laser

Surface Alloying, Laser Cladding, Corrosion Resistance, Microstructure

We have studied the effects of the fine structure of energy levels on the dynamics of the atom and light field. A significant influence is exhibited in the collapse-revival behavior of atomic inversion, the light squeezing, the phase of the field, and the antibunching of a light beam. When the energy difference between the doublet is large (Δ≥20g, where g is the coupling constant), the dynamics of the atomic inversion becomes identical to that of the usual Jaynes-Cummings model, as expected. However, the fine-structure effects on the phase and the antibunching of the light field exist in a much larger range. In particular, for a strong field, the normally ordered variance of the photon-number operator exhibits complicated collapse and revival patterns and the light displays strong antibunching in each revival envelope. Numerical calculations also show that this model does not produce significant squeezing due to the influence of the fine structure. 

In our study of the interaction between few energy level atom and a coherent field, we considered the effect of the excited state's fine structure on the system dynamics. Significant influence exhibited on the collapse-revival behavior of atomic inversion and light squeezing. The numerical calculations show that for weak field, the effects of fine structure may cause disappearance of the collapse and revival phenomena. Our results also show the fine structure has opposite on the light squeezing, this observed on decrease of the amount of squeezing as the average photon number increased.