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Experimental set-up, development, characterization, and calibration of an in-vacuum PIXE system at the tandem accelerator facility of the Atomic Energy Commission of Syria (AECS) is described. The PIXE system calibration involved experimental characterization of the X-ray detector parameters and careful determination of the H-values that control dependence of the detector solid angle with the X-ray energies and correct imperfect values of the detector efficiency. Setting up of an electron flood gun to compensate charge built up and utilization of a beam profile monitor to perform indirect measurement of the beam charge, provide a direct PIXE measurement of thick insulating samples in-vacuum. The PIXE system has been subsequently examined to verify its ability to perform direct PIXE measurements on geological materials. A combination of minimum sample preparation procedures and specific experimental conditions applied enables simple and accurate elemental analysis. Elemental concentrations of several elements heavier than sodium in different reference geological samples, at about 5–10% absolute accuracy for most elements, have been determined. Comprehensive discussion of the obtained elemental concentration values, for most elements of visible X-ray peaks in the PIXE spectra, has been considered. [ABSTRACT FROM AUTHOR]

Egyptian pea cultivars ( Pisum sativum L. cultivars Little Marvel, Perfection and Victory) grown in open-top chambers were exposed to either charcoal-filtered (FA) or non-filtered air (NF) for five consecutive years (2009–2013) at a rural site in northern Egypt. Net photosynthetic rates ( P N ), stomatal conductance (g s ), intercellular CO 2 (C i ) and chlorophyll fluorescence were measured. Ozone (O 3 ) was found to be the most prevalent pollutant common at the rural site and is suspected to be involved in the alteration of the physiological parameters measured in the present investigation. P N of different cultivars were found to respond similarly; decreases of 23, 29 and 39% were observed in the cultivars Perfection, Little Marvel and Victory, respectively (averaged over the five years) due to ambient O 3 . The maximum impairment in P N was recorded in the cultivar Victory (46%) in 2013 when the highest O 3 levels were recorded (90 nL L − 1 ). The average stomatal conductance decreased by 20 and 18% in the cultivars Little Marvel and Perfection, respectively, while the average stomatal conductance increased on average by 27% in the cultivar Victory. A significant correlation was found between P N and C i , indicating the importance of non-stomatal limitations of photosynthesis, especially in the cultivar Victory. The P N vs. Ci curves were fitted to a non-rectangular hyperbolic model. The actual quantum yield (Φ PSII ) and photochemical quenching coefficient (qP) were significantly decreased in the leaves of plants exposed to NF air. Non-photochemical quenching (NPQ) was increased in all cultivars. Exposure to NF air caused reductions in chlorophyll (Chl a ) of 19, 16 and 30% in the Little Marvel, Perfection and Victory cultivars, respectively. [ABSTRACT FROM AUTHOR]

Abstract: Three titanium oxynitride films have been prepared by vacuum arc discharge technique at different chamber temperatures (50°C, 150°C and 300°C). X-ray photoelectron spectroscopy was used to reveal the elemental and chemical compositions by analyzing high resolution spectra of Ti 2p3/2, N 1s and O 1s. Higher temperatures were found to promote the nitride components and to produce nitrogen-rich films. Homogeneity and thickness of the films have been estimated by means of Rutherford Back Scattering technique, which showed that the film thickness increased with the increasing of temperature. A significant improvement in the crystalline quality and texture when increasing the temperature was found by X-ray diffraction technique. Electrical resistivity of the films was measured at room temperature and was found to decrease from 46.6μΩcm down to 26.3μΩcm for the samples prepared at 50°C and 300°C, respectively. [Copyright &y& Elsevier]

Abstract: Manganese leaching and recovery from pyrolusite ore, was investigated by using H2SO4 as a leachant and H2O2 as a reducing agent. The effects of agitation, H2O2 concentration, H2SO4 concentration, liquid/solid mass ratio, leaching time and reaction temperature on manganese recovery were studied. The optimal leaching conditions were determined as 4.0M H2SO4 and 0.8M H2O2 using liquid–solid mass ratio of 5.0 for 90min at 40°C and ore particle size of 44–37μm. Under these conditions, the leaching efficiency was 92.0% for Mn. It was found that the use of H2O2 as a reducing agent for the reductive leaching of manganese increased the leaching rate. Analysis of the experimental results indicted that the leaching process is fitted by a chemical reaction model in temperature range 20–40°C, and at higher temperature, 45–70°C, the diffusion reaction model prevails. Activation energies for these models were calculated to be 49.5kJ∙mol−1 and 10.6kJ∙mol−1, respectively. Based on the experimental results, a separation method and flow sheet were developed and tested to separate high purity MnSO4.H2O (>99.4%). Comparison between the present results and that reported in the literature are given. [Copyright &y& Elsevier]

Abstract: Proton induced X-ray emission (PIXE) has been used to measure trace elements in sediments of Orontes River. Measurements were carried out using a 2MeV proton beam produced from of the 3MV tandem accelerator. Sediment samples were collected from 11 sites covering the important potential pollution sources at the river. The accuracy of the experimental procedure was verified using a certified sediment reference material (IAEA-SL1) and was found to be less than 10%. The results have shown that Pb and As were within the natural levels. In contrast, high concentrations of other elements like Cr, Cu, Ni and Zn have been found at different sites and explained by local human and industrial activities. [Copyright &y& Elsevier]

This paper presents a review of tilt angle and azimuth angles in solar energy applications. The paper involves an overview of design parameter, applications, simulations and mathematical techniques covering different usage application. The number of references analysing the tilt angle deployment in the context of the research papers of the different countries currently having operations in solar systems is much more significant. Different kinds of models and test methods of optimum tilt angle in different solar systems have been developed since 1956 which can be distinguished by their particular mathematical models or tracking techniques as shown in the latest researches. The mathematical models allows the calculation of different parameters of the solar radiation, the angle of inclination, and the optimum tilt angle of the collecting surface and the effects acting on the system. [ABSTRACT FROM AUTHOR]

Abstract: Experimental runs were done to estimate the adsorption characteristics of granular activated carbon (GAC)/R134a pair. A laboratory scale test rig was designed and built to run the experiments. The adsorption capacity of the GAC was studied at different temperatures 25°C, 35°C, 45°C and 65°C. Pressure and time were recorded during the experiments. The maximum adsorption capacity was found to be 1.68kgR134a kgcarbon −1 at 25°C after 1000s. The activation energy and the exponential constant were estimated to be 9575Jmol−1 and 1.83 respectively. [Copyright &y& Elsevier]

Abstract: This study introduces a review for the potential cooling systems which uses carbon materials as an adsorbent. Also, the adsorption carbon pairs (pairs where the carbon is the adsorbent) which is still under researches were reviewed. The maximum COP (coefficient of performance) of the cooling systems was 0.8 for activated carbon/ethanol pair. The study concluded that the performances of the potential adsorption cooling systems using carbon are still not satisfied. It was concluded that there is an opportunity for the adsorption carbon pairs to introduce a new cooling system with a promising performances. [Copyright &y& Elsevier]

This paper presents a review of the design parameters, mathematical techniques and simulations used in the design of parabolic trough solar systems, along with a review on their applications. Recent studies that analyze the deployment of solar parabolic trough collectors (SPTC) in different countries and the operational SPTC plants are also presented and discussed. The paper also discusses the different kinds of software and test methods of solar collectors developed since 1981 which can be distinguished by their particular mathematical models or tracking techniques. In particular, since the mathematical models are especially required for the design, analysis, testing and validation of the systems results as they provide an approximation of the dynamic behavior of the physical properties of the system, they are discussed in depth. The mathematical models allow the calculation of different parameters of the solar parabolic trough system, the angle of inclination of the collecting surface and the forces acting on the system. The validity and experimental validation of the major mathematical models on practical solar parabolic trough concentrators, receivers and other components of different dimension are also reviewed. The paper showed the optical efficiency values are close to 63% and the theoretical peak optical efficiency reached 75%. [ABSTRACT FROM AUTHOR]

This paper reviews the status of microbial electrolysis cells (MEC) as a mean for hydrogen (H 2 ) production and urban wastewater treatment method. A case study of the Kingdom of Saudi Arabia (KSA) under MEC concept was developed. KSA is the world’s third largest per capita water user country with no lakes and rivers. Every year, around 1.17 and 0.38 billion m 3 of domestic and industrial wastewater is generated respectively. The KSA government is seeking sustainable solutions for wastewater treatment and waste-to-energy (WTE) production to bridge the ever increasing water and energy demand-supply gap. However, there is no WTE facility exists to convert the wastewater into energy. Moreover, the potential of wastewater is not examined as an energy recovery substrate. This study, for the first time, estimated that a total electricity of 434 MWe can be produced in 2015 from the KSA’s wastewater if MEC technology is employed. Similarly, an estimated total electricity of 612 and 767 MWe can be produced for the years 2025 and 2035 from the domestic and industrial wastewater by using MEC technology. A surplus electricity of 508 and 637 MWe for the years 2025 and 2035 respectively can be added to the national grid after fulfilling the energy requirement of MEC wastewater treatment plants. Collectively, MEC will contribute 20.4% and 25.6% share of the KSA government’s WTE target of 3G W in 2025 and 2035 respectively. A number of challenges in MEC such as ohmic and concentration losses, saturation kinetics and competing reactions that lower the H 2 production are discussed with their potential solutions including, the improvements in MEC design and the use of appropriate electrolytes, antibiotics and air or oxygen. [ABSTRACT FROM AUTHOR]

In this paper, a feasibility study is carried out in order to investigate the description, working principles of the solar parabolic dish systems worldwide, and their potential use in some countries are given. A study of the system is presented, which able to show the performance of the system and accounting for the main technical aspects of the concentrator, receiver and Stirling engine. The study reviews the parabolic solar dish technologies and the design factors adapted in different applications such as material of the reflector concentrators, shape of the reflector concentrators and the receiver, solar radiation at the concentrator, diameter of the parabolic dish concentrator, sizing the aperture area of concentrator, focal length of the parabolic dish, the focal point diameter, sizing the aperture area of receiver, geometric concentration ratio, and rim angle. In order to identify the optimum design feasible option for installation of the solar dish plants, the technical characteristics of some implemented solar dishes worldwide are presented. The study take into consideration available solar potential and the different designs of solar dishes. [ABSTRACT FROM AUTHOR]

Airborne concentrations of Polycyclic Aromatic Hydrocarbons (PAH), quinone and nitro derivatives have been measured at three sites on the coast of Saudi Arabia to the north of the city of Jeddah. The PAH show a general reduction in concentrations from northwest to southeast, consistent with a source from a petrochemical works to the northwest of the sampling sites. In comparison, the concentrations of quinones show little variation between the sampling sites consistent with these being predominantly longer lived secondary pollutants formed from PAH oxidation. The nitro-PAH show a gradient in concentrations similar to but smaller than that for the PAH suggesting a balance between atmospheric formation and removal by photolysis. The 2-nitrofluoranthene:1-nitropyrene ratio increases from north to south, consistent with atmospheric chemical formation of the former compound, while the ratio of 2-nitrofluoranthene:2-nitropyrene is consistent with hydroxyl radical as the dominant reactant. An investigation of the changes in PAH congener ratios during air mass transport along the Red Sea coast shows consistency with reaction with a relatively low concentration of hydroxyl radical only for the day with the highest concentrations. It is concluded that while PAH degradation is occurring by chemical reaction, emissions from other locations along the air mass trajectory are most probably also leading to changes in congener ratios. [ABSTRACT FROM AUTHOR]

Modeling and simulation for different parabolic dish Stirling engine designs have been carried out using Matlab®. The effect of solar dish design features and factors such as material of the reflector concentrators, the shape of the reflector concentrators and the receiver, solar radiation at the concentrator, diameter of the parabolic dish concentrator, sizing the aperture area of concentrator, focal Length of the parabolic dish, the focal point diameter, sizing the aperture area of receiver, geometric concentration ratio, and rim angle have been studied. The study provides a theoretical guidance for designing and operating solar parabolic dish Stirling engines system. At Zewail city of Science and Technology, Egypt, for a 10 kW Stirling engine; The maximum solar dish Stirling engine output power estimation is 9707 W at 12:00 PM where the maximum beam solar radiation applied in solar dish concentrator is 990 W/m 2 at 12:00 PM. The performance of engine can be improved by increasing the precision of the engine parts and the heat source efficiency. The engine performance could be further increased if a better receiver working fluid is used. We can conclude that where the best time for heating the fluid and fasting the processing, the time required to heat the receiver to reach the minimum temperature for operating the Solar-powered Stirling engine for different heat transfer fluids; this will lead to more economic solar dish systems. Power output of the solar dish system is one of the most important targets in the design that show effectiveness of the system, and this has achieved when we take into account many factors in the design of the solar dish system. One of these factors is the reflector material of the concentrator and using the results from the Matlab simulation program; where the Polymeric Film, Non Metal reflectors, with a net conversion power of more than 97.07%, still holds the conversion record than the Anod Aluminum reflectors, which has a net conversion power 85.97% with respect to the polished stainless reflectors with a net conversion power 49.52% from the 10 kW Stirling engine. Where the power output differ as 9707, 4952, 8597 W, respectively from the 10 kW Stirling engine. It is shown that there are changes in Stirling power output for different materials, which guide us to select the optimum material, based on the targeted power output and cost. Our target to reach the optimum power that we need it in the design 10 kW power output design as an example from the solar dish Stirling engine. [ABSTRACT FROM AUTHOR]

The present study aims at examining the feasibility of using synthesized magnetic nano zeolite for the sorptive removal of cesium and strontium ions existing in the liquid radwaste stream. Cs + /Na + and Sr 2+ /Na + binary ion exchange experiments were performed in the batch mode at different three temperatures (298,303 and 313 K), optimized proton concentration (pH), equilibrium time and constant total normality. The thermodynamic analysis of both binary systems was performed using four types of model equations: Langmuir; Freundlich; Radlish-Peterson and thermodynamic equilibrium models. The extended Debye–Huckel relation and the Wilson equation were used to estimate the solution and the solid phase activity coefficients, respectively. The results obtained during this study demonstrated the correlation of the four examined models with the experimental equilibrium data, which proved to be satisfactory. On the other hand, the thermodynamic non-idealities was found to give the best results. Thermodynamic parameters such as enthalpy change, Gibbs free energy change and entropy change were also calculated. The obtained affirmative results demonstrated that the synthesized magnetic nano zeolite can be used as an efficient sorbent for the removal of Cs + and Sr 2+ ions from the contaminated solutions. [ABSTRACT FROM AUTHOR]

Abstract: A series of nano-sized Al-substituted manganese zinc ferrites, Mn0.8Zn0.2Fe2− x Al x O4 (x =0.0−1.0), with a cubic spinel crystal structure were prepared through the citrate sol-gel auto-combustion method. Thermogravimetric measurements revealed that the optimum calcination temperature for complete formation of ferrites is 300°C. At higher calcination temperatures X-ray diffraction indicated the presence of Fe2O3 and Mn2O3 secondary phases, attributed to the ferrites decomposition. The average crystallite size, calculated using the Debye–Scherrer equation, lies in the range 5–38nm. The gradual decrease in lattice parameter with increasing Al-content can be attributed to the smaller ionic radii of the Al3+ ion. The TEM image showed large agglomerates of strongly connected cubic aggregates. FT-IR spectra exhibited two prominent absorption bands, ν 1 and ν 2, characteristic for the spinel structure. VSM measurements indicated a gradual decrease in the saturation magnetization with increasing Al-content, until it vanished at x =0.8, followed by a slight increase. The reduction in coercivity with increasing Al-content can be ascribed to the effect of magneto-crystalline anisotropy. Based on XRD, FT-IR and VSM studies, an appropriate cation distribution for the present investigated system was suggested. The temperature dependence of the AC-conductivity as a function of the applied frequency showed semiconducting behavior with a transformation in the conduction mechanism from the ferrimagnetic to the paramagnetic state for ferrites with x ⩽0.4. [Copyright &y& Elsevier]