Vol. 2 Issue 1
Muhammad Albar and D.L. Johnson
Coxeter-type generalizations of the braid groups are introduced, and their structure is elucidated in the case when the associated graph is a circle
M.1. Naguib, Nahed Z. Haikal and Souad Gouda
This investigation evaluates the role of chromium in the growth of a tomato phytopathogenic fungus (Fusarium oxysporum f.sp. lycopersici) and a tomato rhizospheric fungus (Cunninghamella echinulata).
Hexavalent chromium was much more toxic in the linear growth of the two experimental fungi than the trivalent ion, Cunninghamella echinulata being more tolerant to the large doses than Fusarium oxysporum f.sp. lycopersici. In the meantime, chromate and chromic has less effect on dry weight gain in Fusarium oxysporum than dichromate. Under all conditions, the inhibition of dry weight gain increased with the rise of concentration of any chromium ions but was partially overcome with age.
A.R. Hassan
The polarization dependence of three- photon absorption in solids is developed using the Wigner- Eckart theorem for finite symmetry groups. The expression for the absorption coefficient is separated into two parts:
1) The geometrical part, which depends on the polarization vectors of the three photons.
2) The dynamical part, which contains the product of three electron- photon matrix elements.
New information can be gained by studying these two parts. An application to TICI crystal is given and an experimental method is suggested.
E.E. Shaisha and A.A. Bahgat
A field assisted ion exchanged soda-lime silicate glass tubes were soaked in a molten bath of potassium nitrate at different temperatures and different times. An attempt was made to study the effect of these parameters on the residual stress profiles. The residual stress arising due to a singly and doubly ion exchange at two different temperatures was examined. The results are discussed on the basis of the stress relaxation and ionic diffusion.
F.A. Abou-Elfotouh and M.A. AI-mass'ari
In this work a solar thermionic power plant is proposed and analyzed. The geometric configuration of the system, which based on the central thermal receiver tower concept, could be optimized to achieve an average concentration ratio more than 1800. In a laboratory model for the heat transfer system, the cathode of the thermionic diode is heated by a hot air flow supplied from the cavity. A silicon-carbide cavity with depth-to-width ratio 1.2 was found successful. By building a thermionic diode of 20 percent efficiency into a solar electric power system, the cost-per-unit-power output can be reduced by 3 to 5 percent
T. EI-Dessouki, F. Sharaf, I. Fouda and N. Khalil
The thermal effect of a ruby lased on glass substrates coated by different thin metal films of silver, copper, aluminum, nickel, chromium and antimony is studied. It is shown that the depression in the damaged area is linearly dependent on the thickness of the metal films as well as on their thermal conductivities. The depressions are found to be greater than those produced in uncoated glass
N.A. Al-Asgah
The morphology and histology of the alimentary tract of Garra tibanica is described. Specializations in the form of the esophageo-intestinal sphincter, the intestinal swelling and the intestinal looping are reported. The histological features of the esophageal lining are characterized by ciliated columnar epithelium intermingled with goblet cells. Minor histological changes occur at the esophageo- intestinal sphincter, at the intestinal swelling and intestinal looping and the the distal intestine; otherwise, the intestinal lining is much the same throughout. The chief difference is in the degree o complexity and depth of folding. Neither a basement membrane nor a stratum compactum are evident.
Momtaz H. Ismail
The development of the chondrocranium of two post buccal stages of Sarotherodon galilaeus (= Tilapia galilaea) (9 mm and 12 mm total length; 11 and 14 days old after fertilization, respectively) is described and compared with that of other bony fishes.
In the 9 mm stage, absorption of cartilage is observed at the level of the fenestra hypophysea and becomes more pronounced in the 12 mm stage, early as compared with that in other bony fishes. The disparity is probably due to differences in environmental conditions.
The neurocranial pharyngobranchiad apophysis, characteristic of the cichlid neurocranium, is developed from stage 9mm onwards as a slight ventral projection of the neurocranial base in the optic phase.
The parachordal plates are connected posteriorly with each other by means of an epichordal commissure.
The taenia tecti medialis originates as a posterior median extension of the epiphyseal cartilaginous bar.
An interorbital septum is present. It consists anteriorly of cartilage and posteriorly of connective tissue membrane.
A single, median, independant rostral cartilage is present dorsal to the ethmoid plate.
The palatoquadrate cartilage articulates anteriorly with the neurocranium by means of an ethno palatine articulation; a rostropalatine articulation, however is absent.
Mohammed S. AI-Khalifa
The changes with age in the ultrastructure of the fat body in female Sitophilus granarius are described. The fat body is much reduced in the aged animal. Ageing causes extensive ultrastructural changes in the cell organelles of the fat body cells including an increase in adi electronic lysosome- like bodies, autophagic vacuoles and lipid droplets, together with a decrease in glycogen particles. Many of the mitochondria have electron- translucent matrices. The changes observed are discussed in relation to prevent observations on other insect species.
J. Devi Prasad, I.I. Bashour and A. Al-Shanghitti
Micronutrients (Fe, Zn, Mn and Cu) contents in 102 soil samples selected from major agricultural areas (Al-Kharj, Al-Hasa, Qasim, Taif, and Wadi Dawasir) representing a wide range of soils cultivated for crop production in Saudi Arabia, were analyzed by the DTPA method. Values in parts per million in the surface soils of the 23 locations ranged rom 1.10 to 11.70 for Fe, 0.12 to 3.20 for Zn, 0.40 to 26.0 for Mn and 0.20 to 3.20 for Cu. None of the surface soils showed Cu deficiency, and only 2% of the samples were deficient in Mn. Iron was deficient in 78% of the samples and Zn in 70% of the samples. Distribution of Zn and Cu throughout the profile below the surface layers was uniform with larger amounts in surface horizons. Contents of Fe and Mn generally decreased with depth.