The prediction of size distribution curves of jaw crushers product is one of the most important parameters in controlling its use. Experimental and analytical studies are carried out on cubic samples of marble and limestone. The study shows that the size distribution curves in crushing obey the Gamma distribution. Definite relationships are obtained between either average diameter of the product or standard deviation and the set of the jaw crusher (S). The experimental values of the parameters of Gamma distribution (act, Pact) are compared with the calculated ones obtained from the above relationships. It was found that the greater the set of the jaw crusher, the greater the deviation.
The oxidation ratio ((2Fe2O3 x100)/ (2Fe2O3 + FeO)) of the granitic rocks of the Aswan batholith range from 8 to 90 and increase with the increase of differentiation index from older to younger rocks. The batholith was formed by crystallization of magma under buffered conditions with respect to oxygen. The buffer was magnetite, lower levels of oxygen pressure were maintained during the formation of the earlier phases of the batholith, and higher pressures of oxygen prevailed during the generation of the later phases. The earlier phases were probably produced by melting pf parental mantle-derived anhydrous material and crustal rocks. The later phases were probably formed entirely by melting crustal materials of sialic composition. The initial Sr87/Sr86 ratios of the earlier phases range from 0.7052 to 0.7352 and may support this view.
Mohamed I. Naguib, Nahed Z. Haikal and Fadia F. Ali
Fungal felts, produced by spore germination on patoran or diuron, seemed to be adapted to the continuous supply of large doses of the herbicides (up to 160 micro g/ml). A higher biomass yield followed continuous culturing of the mats of Cunninghamella echinulata on fresh herbicide-containing media, though this was smaller than in control samples. The effect was more substantial after patoran treatment as compared with diuron.
Patoran induced a consistent inhibition of respiratory carbon dioxide output even after the pretreated mycelia were transferred to a plain nutritive medium. Continuous supply of the herbicide was highly toxic. However, C. echinulata seemed more adapted to diuron.
The deleterious effects of pretreatment with the herbicides was more apparent on nitrogen metabolism; secretion of nitrogen from the mycelium increased with both treatments, particularly with the continuous supply of the herbicides. Recovery, after an initial herbicide treatment, seemed to induce better nitrogen accumulation than continuous supply of the herbicides. The lower residual nitrogen content of mycelia continuously supplied with the herbicides, as compared with their respective 'recovering' samples, indicates lesser tolerance of the former samples to the herbicides with prolonged exposure to the large doses.
Twenty seven sites around the islands of Bahrain were studied regarding the distribution and density of waders. Site features, such as slope, sediment grain size and dry intertidal area were examined. The biomass as dry weight per square metre was calculated for each site. A greater density of wading birds was shown in sites with a large dry intertidal area, a very gentle slope and high value of biomass which reached 16.84g/m2 in Ras Hayan site. The high values of counts ranged between 100-145 birds/minute while the lowest was 2 birds/minute. Areas attractive to migratory waders are located mainly on the sheltered eastern shore of the main island of Bahrain. Twenty eight different species of waders were identified during the present field study. Human activities such as filling and land reclamation had influenced some of the important areas which previously attracted waders.
A total of thirty-five samples of the economic grade Jordanian Upper Cretaceous phosphorites were analysed for certain major and rare earth elements (REE) with an overall objective of understanding phosphogenesis conditions. These samples represent pelletal (granular) phosphorites with traces of carbonates and marl. The deposits are of shallow subtidal environment of authigenic nature. The relative abundance of REE normalised to shale standard is indicative of proximal to onshore phosphorites. The distribution patterns of the REE show a depletion in cerium (Ce) and light REE (LREE) and enrichment in the heavy REE (HREE), indicating marine depositional environment. The highly negative Ce anomalies of these samples indicate phosphogenesis under oxic marine condition which are interpreted as a signature of deep cold upwelling seawater on shallow epeiric shelf, cleanliness of these deposits from clay minerals and to the very limited diagenetic processes affecting them after deposition