Search Results

You are looking at 1 - 10 of 21 items for

  • Author or Editor: S. Saleh x
  • Refine by Access: All Content x
Clear All Modify Search

In the present study the crustal structures of Nile Delta, including Greater Cairo province, and its surroundings, were evaluated using 3D forward gravity and magnetic modeling. The interpretation is also based on the seismic reflection results, well logs data and previous density models. The present results allow to improve the understanding of both the crustal thicknesses and density distributions between the sedimentary cover and the upper mantle in the study area.The high Bouguer anomalies near the Mediterranean coast are mainly caused by deep-seated structures. The crust beneath the Mediterranean coastal region is typically continental, with a thickness of 24 km beneath Rositta and Damitta branches, which increases toward the south. The Greater Cairo province has been modeled with maximum crustal thickness of ca. 34 km. The negative gravity anomalies with minimum values are due to the effect of sedimentary cover and/or basement relief geometry.The main results of this work suggest that the study area could be divided into three different distinctive tectonic zones according to their Moho depth and crustal structures. The southern zone (unstable shelf zone) which covers the Greater Cairo province is characterized by maximum crustal modeled thickness. It also represents the most seismically active tectonic zone in the study area. On the contrary the middle and northern zones show a thinned crustal layer and a correspondingly thicker sedimentary cover.Furthermore, the magnetic anomalies along the Greater Cairo, as deduced from the 3D magnetic modeling, are mainly caused by the upper crustal structures. In particular, the high magnetic anomalies of the southern part of the studied area are interpreted as related to variation in the basement relief near the surface, resulting from block faulting and/or compressional folds.In the northern region near the Mediterranean coastal area the highest magnetic susceptibility anomaly values is affected by the shallow smooth relief of the lower crustal layer. Finally, limited, shallow-seated basaltic intrusions were modeled beneath the western side of Nile Delta. The existence of these basaltic intrusions suggests that the study area was influenced by the opening of the Red Sea and/or Gulf of Suez during the Oligocene time.

Restricted access

Abstract  

Crushing or otherwise processing potato and subsequent mild washing of the pulp produces mostly granular and fibrous starch. These fibers are experimental carrier material for microbes in bioremediation of polluted waters. This method offers the benefit of increasing the exposure of the microbes to the pollutant by increasing their residency within the site. Because of the physical nature of the material, it also offers the possibility of carrying, in addition to the microbes, essential macronutrients such as nitrogen and phosphorous that would be limited in availability in contaminated waters. We have previously reported on the physical nature of these fibers through thermal analysis and on their ability to bind/aggregate bacteria. We have extended that study in this report by infusing the fibers with a source of nitrogen and phosphorous, namely ammonium phosphate. The TG curves for ammonium phosphate-infused white and sweet potato fibers exhibited three main mass loss steps corresponding to the three exothermic DTG peaks. Infusion with the ammonium phosphate salt also affected the bacterial binding/aggregation capacities. The range of their binding capacities decreased to a range of 26.9–43.3% compared to untreated fibers.

Restricted access

Three-dimensional gravity modeling has been performed for the Eastern Mediterranean including the northeastern Egyptian off-shore area. The gravity models and seismic profiles indicate that a transition from two layer continental crust to a simple layer oceanic crust takes a place along the Levantine margin. The transition along three profiles is located beyond the north African continental margin and it is quite gradual. The crust under the Levantine basin is typically oceanic and slightly thin with 13 km thickness, however it is typical continental under the Egyptian off-shore and having 30 km thickness. The obtained results reflect a large sedimentary sequence of 14 km under the Levantine basin. Since the sediments recovered by the Oceanic Drilling Program Leg160 in the eastern Mediterranean ranged from Pleistocene to Cretaceous, this reflects fairly high sedimentation rate. Distribution of recent earthquake foci indicates that almost all earthquakes occurred along the western and central segments of the Cyprean arc while they completely disappear along the eastern segment. This means that collision between Cyprus and the Eratosthenes seamount is marked by seismic activity and clearly affects the shape of the Cyprean arc. This collision represents a transition zone between active compression and probable subduction in the western segment and diffuse transtension through the eastern part of the arc. Incipient collision between Cyprus and Eratosthenes seamount probably began in Pleistocene time.

Restricted access

Abstract  

The adsorption behaviour of La/Ce system on Dowex 50W-X8 in different media, namely, nitric acid, acetate buffer and citrate buffer was studied as a function of the concentration of nitric acid and buffer pH. In addition, in cation-exchange column chromatography experiments, three different eluants, namely, citrate buffer of pH 5.5, 0.1 M EDTA and 0.2 M α-HIBA, were employed for separation of Ce(III) from La(III). The optimum conditions for improvement of radiochemical separation of no-carrier-added 139Ce from proton irradiated lanthanum were applied using the most suitable chelating agent 0.2 M α-HIBA. The purification of 139Ce from macro amount of La(III) was done using two columns in a sequence. The target was prepared by pressing. The production of high radionuclidic and chemical purity 139Ce via irradiation of lanthanum oxide target at MGC-20 cyclotron of proton energy 14.5 MeV was described. The experimental yield was found to be 200 kBq/μA h.

Restricted access

Abstract  

The adsorption behaviors of no-carrier-added radioiodine and a bulk of tellurium on the anion-exchange resin in different media, namely, hydrochloric acid and sodium hydroxide solution were studied. The effect of shaking time on the uptake percentage of the no-carrier-added radioiodine was carried out using the batch technique in both 7 M HCl and 8 M NaOH. In column experiments for the separation of radioiodine from Te-bulk, different liquid phases such as, 2 M NaOH, 70 % methanol, a mixture of ethyl acetate to ethanol (1:1 v/v) and 5 mM tetra-butyl ammonium bromide in ethyl acetate without and with few drops of 0.01 M sodium metabisulfite were employed as eluants. Not only this, the bed depth of the resin was also taken into consideration. Different weights of Amberlyst A-27 correspond to different bed depths (3, 4, 5, 6 cm) were employed. Under the optimum conditions the overall radiochemical yield for the separated radioiodine was 90 % and recovery of Te-bulk was 98 %.

Restricted access

Abstract  

Zinc diethyldithiocarbamate, zinc diethyldithiocarbamate-phosphate and zinc phosphate have been synthesized. They have been characterized using DTA-TG, IR spectra and X-ray. The dithiocarbamate and phosphate contents have been determined spectrophotometrically and volumetrically, respectively. Fungicidal activity of the compounds has been tested by well diffusion method using fungi Fusarium sp.

Restricted access

A potential bacterial carrier for bioremediation

Characterization of insoluble potato fiber

Journal of Thermal Analysis and Calorimetry
Authors:
C. Elliott
,
Z. Ye
,
S. Mojumdar
, and
M. Saleh

Abstract  

One of the limiting factors to the effectiveness of biostimulation and bioremediation is the loss of inoculated material from the site. This can occur by a number of pathways, but is particularly problematic in open water systems where the inoculated material is simply lost in the water. It is desirable to develop new material, a matrix, within which bacteria and/or biostimulants can be incorporated. We have investigated the basic physical properties of insoluble potato starch to eventually evaluate its use as such a matrix. Insoluble starch fibers were prepared from white potato (Solanum tuberosum) and sweet potato (Ipomoea batatas) and were compared for their melting temperature by DSC and their ability to bind/aggregate bacteria. The DSC curves for white and sweet potato showed that the melting temperature is 127.34 and 133.05�C for white and sweet potato fibers, respectively. The TG curves for white and sweet potato starches exhibited one main mass loss step corresponding to the DTG peak temperature at 323.39 and 346.93�C, respectively. The two types of fibers, however, showed different binding/aggregation capacities for bacteria, with white potato approximately twice as many cells of Burkholderia cepacia (22.6 billion/g) as cells of Pseudomonas putida. The reverse was true for fibers from sweet potato, binding twice as many cells of Pseudomonas putida (23 billion/g) as cells of Burkholderia cepacia.

Restricted access

Abstract  

For the determination of cadmium in sea water, a neutron activation analysis method involving a preconcentration step has been developed. Preconcentration is achieved by co-precipitation of cadmium dibenzyldithiocarbamate with phenolphthalein. The precipitate is collected on 0.45 μm membrane filters and cadmium is determined by instrumental neutron activation analysis. A115mCd radio tracer was used to establish optimum conditions and to evaluate the chemical yield.

Restricted access

Abstract

Residues of the fungicides difenoconazole, propiconazole, cyflufenamid, and mandipropamid were determined in tomato fruit using acetonitrile for extraction and LC-MS/MS for quantification. Validation criteria include linearity range, the limit of detection (LOD) and limit of quantitation (LOQ), accuracy in terms of precision and trueness, and matrix effect were studied. The recovery rates of the method ranged from 91.8 to 106.3%. The precision of the method in terms of repeatability at one day (RSDr) and between three days (RSDR) ranged from 2.8 to 6.4% and from 4.3 to 7.6%, respectively, with good trueness from 92.2 to 96.4%. Matrix effects (suppression effects) ranged from 3.8% to 11.1%. The validated method was used to evaluate the dissipation kinetics of three different premix formulations: 30% EC (15% difenoconazole + 15% propiconazole), 14% DC (12.5% difenoconazole + 1.5% cyflufenamid), and 50% SC (25% difenoconazole + 25% mandipropamid) used on field tomatoes in Egypt. A first-order kinetic equation best describes residue dissipation. The calculated half-lives of difenoconazole, propiconazole, cyflufenamid, and mandipropamid were 2.01–2.27, 1.89, 1.97, and 1.71 days, respectively. The dissipation rate of difenoconazole did not differ significantly in the three premix formulations. Mandipropamid also dissipated faster compared to the other fungicides tested. The chronic dietary risk assessment results showed a minimal risk to adult Egyptian consumers. Waiting periods were advised for the safe consumption of tomatoes treated with the tested premix formulations.

Open access