Design,Facile Synthesis and Characterization of Porphyrin-Zirconium-Ferrite@SiO2 Core-Shell and Catalytic Application in Cyclohexane Oxidation

Silicon - In this study, a new magnetic ZrFe2O4@SiO2-TCPP nanocatalyst with high efficiency was used for the oxidation of cyclohexane to cyclohexanone (Ke) and cyclohexanol (Al). The mesoporous...     

Preparation, Characterization and Photocatalytic Properties of Ba-Cd-Sr-Ti Doped Fe3O4 Nanohollow Spheres on Removal of Congo Red Under Visible-Light Irradiation

In this study, Ba-Cd-Sr-Ti doped Fe₃O₄ nanohollow spheres were successfully prepared via a simple solvothermal method. The crystal size, structure, morphology and elemental analysis of the as-prepared sample were investigated in detail by X-ray diffraction (XRD), FT-IR, scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy, respectively. Magnetic hysteresis measurement was carried out on a vibrant sample magnetometer (VSM) showing the soft ferromagnetic property at room temperature. The synthesized nanohollow spheres were employed as a photocatalyst to study the photocatalytic degradation of dye contaminations. The UV-Vis results showed that the specimen could well catalyze the decolorizing of congo red (CR) solution and a removal efficiency of 99.5 % was obtained at pH 6. The optical characteristic of the products was studied by estimating the band-gap energy based on diffuse-reflectance spectroscopy (DRS) which represented the doped magnetite with semiconductor metals to be more prone in the visible region as compared to UV region. Some factors such as initial dye concentration, pH, and contact time influencing the decomposition of CR were evaluated.     

Fabrication and characterization of silk/forsterite composites for tissue engineering applications

In this research, novel composite scaffolds consisting of silk fibroin and forsterite powder were prepared by a freeze-drying method. In addition, the effects of forsterite powder contents on the structure of the scaffolds were investigated to provide an appropriate composite for bone tissue engineering applications. The morphology studies using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques showed that the forsterite ceramic was well distributed throughout the structures of SF/forsterite scaffolds. Furthermore, the forsterite powder (up to 40 wt%) was homogenously distributed within the silk fibroin as a matrix.     

Instability,heat transfer and flow regime in a two-phase flow thermosyphon loop at different diameter evaporator channel

In this study, the influence of different channel geometries on heat transfer, flow regime and instability of a two-phase thermosyphon loop, is investigated. Instabilities in flow regime and heat transfer, at low and high heat fluxes, are observed. Bubbly flow with nucleate boiling heat transfer mechanism, confined bubbly/slug flow with backflow for small channel height (H) and finally slug/churn flow at high heat fluxes are observed. This study shows that flow and thermal instability increases as channel height (H) decreases and also heat transfer coefficient increases with increasing channel height and heat flux. Bubbly flow characterizes the flow regime at high heat transfer coefficients while confined bubbles, backflow and intermittent boiling are more significant for low channel heights with lower heat transfer coefficient and critical heat flux.     

Design and cost analysis of an automatic meter reading system for Electricité du Liban

This paper summarizes the results of a study for modernizing the electricity metering, billing and collection processes for Electricité du Liban (EDL), the national power company of Lebanon. The objective of this study is to provide EDL with the best alternatives for modernizing their electricity metering of low-voltage customers. These customers are currently being metered using a variety of old and new electromechanical meters. The metering process at EDL is manual, and prone to errors. The existing system does not provide EDL with reliable methods to readily check bills, identify problematic customers, and reduce fraud. Therefore, EDL’s modernization requirements include an automated system capable of enhancing current metering processes, minimizing fraud, and maximizing revenue collection. This paper will describe the functional requirements of EDL and investigate the feasibility of using Automatic Meter Reading (AMR) technology to satisfy these requirements. Both procedural and equipment modernization techniques will be identified and assessed. The proposed modernization system will make EDL’s metering activities as advanced as those of modern utilities. Most importantly, with the modernized system, EDL will regain the confidence of its customers, and would become a highly reputable and revenue generating organization.     

A supply model for crude oil and natural gas in the Middle East

Crude oil (CO) and natural gas (NG) play an important role in the world economy. The Arab countries (ACs) share 64% of the total oil reserves and 40% of the NG reserves [OPEC, 2003. The Annual Statistical Bulletin]. On the production side, ACs contribute to 30% and 9% of the world production of CO and NG, respectively. Accurate forecast models are needed to do better planning and create less risky business environment. In this paper, an econometric model is built to capture the behavior of CO and NG production in the ESCWA¹ countries. The model is used to forecast future production trends of CO and NG, and thus provide a powerful tool for researchers, planners and investors working in the energy field.     

Using a novel technique to shape a refractory castable by Cold Isostatic Pressing and a study of the effect of pressure on the hydration reaction of high-alumina cement

Calcium aluminate cements are the most hydraulically setting cements used for refractory castables. The anhydrous phases of this type of cements incorporate CA, CA₂ and traces of C₁₂A₇ and alpha-alumina where C and A stand for CaO and Al₂O₃, respectively. Hydration starts to form the hexagonal crystals of CAH₁₀ (H denoting H₂O) and C₂AH₈, which convert to the cubic crystals of C₃AH₆ and AH₃ by the passage of hydration time. In this work, Al₂O₃−C (alumina-graphite) castables were shaped by cold isostatic pressing at 100 to 400 bars (≈100 to 400 Kg/cm²). Hydration and conversion reactions were studied using the Ratio of Slopes Method for quantitative XRD studies after 3 and 28 days. The results showed that by increasing the pressure, the kinetics of the hydration reaction will increase and higher strengths can be obtained, which supports the idea of forming this graphite containing castable by Cold Isostatic Pressing (CIP) in industrial applications for special refractories.     

Heat transfer in the evaporator of an advanced two-phase thermosyphon loop

As heat generation from electronic components increase and the limit of air-cooling is reached, the interest for using liquid cooling for high heat flux applications has risen. Thermosyphon cooling is an alternative liquid cooling technique, in which heat is transferred as heat of vaporization from evaporator to condenser with a relatively small temperature difference.The effect of fluid properties, the structure of wall surfaces, and the effect of system pressure was investigated and reported previously by the author. In this paper, the influence of heat flux, system pressure, mass flow rate, vapor fraction, diameter of evaporator channel and tubing distance between evaporator and condenser on the heat transfer coefficient of an advanced two-phase thermosyphon loop is reported. The tested evaporators were made from small blocks of copper with 7, 5, 4, 3 and 2 vertical channels with the diameters of 1.1, 1.5, 1.9, 2.5, and 3.5 mm, respectively and the length of 14.6 mm. Tests were done with isobutane at heat fluxes ranging between 28.3 and 311.5 kW/m².     

Void Formation and Plastic Deformation Mechanism of a Cold-Rolled Dual-Phase Steel During Tension

The void formation and plastic deformation micromechanisms of a cold-rolled DP600 steel during tensile loading were studied by scanning electron microscopy(SEM) and electron backscatter diffraction(EBSD).The SEM observations revealed that the main void nucleation mechanism in the DP600 steel is decohesion at the ferrite-martensite interfaces.The voids were mostly observed between the closely spaced martensite islands situated at the boundaries of relatively finer ferrite grains.The EBSD results indicated a strain gradient developed from the ferrite-martensite and ferrite-ferrite interfaces into the interior of ferrite grains during the tensile deformation,which led to a stress concentration at these interfaces.Moreover,it was demonstrated that local misorientation inside the finer ferrite grains surrounded by martensite islands was higher than that for the coarser ferrite grains,which made the former more prone to void initiation.     

Early white blood cell dynamics after traumatic brain injury: effects on the cerebral microcirculation

Increasing clinical and experimental evidence suggests that traumatic brain injury (TBI) elicits an acute inflammatory response. In the present study we investigated whether white blood cells (WBC) are activated in the cerebral microcirculation early after TBI and whether WBC accumulation affects the posttraumatic cerebrovascular response. Twenty-four anesthetized rabbits had chronic cranial windows implanted 3 weeks before experimentation. Animals were divided into four experimental groups and were studied for 7 hours (groups I, IIa, and III) or 2 hours (group IIb). Intravital fluorescence videomicroscopy was used to visualize WBC (rhodamine 6G, intravenously), pial vessel diameters, and blood-brain barrier (BBB) integrity (Na+-fluorescein) at 6 hours (groups I, IIa, and III) or 1 hour (group IIb) after TBI. Group I (n = 5) consisted of sham-operated animals. Groups IIa (n = 7) and IIb (n = 5) received fluid-percussion injury at 1 hour. Group III (n = 7) received fluid-percussion injury and 1 mg/kg anti-adhesion monoclonal antibody (MoAb) "IB4" 5 minutes before injury. Venular WBC sticking, intracranial pressure (ICP), and arterial vessel diameters increased significantly for 6 hours after trauma. IB4 reduced WBC margination and prevented vasodilation. Intracranial pressure was not reduced by treatment with IB4. Blood-brain barrier damage occurred at 1 hour but not at 6 hours after TBI and was independent of WBC activation. This first report using intravital videomicroscopy to study the inflammatory response after TBI reveals upregulated interaction between WBC and cerebral endothelium that can be manipulated pharmacologically. White blood cell activation is associated with pial arteriolar vasodilation. White blood cells do not induce BBB breakdown less than 6 hours after TBI and do not contribute to posttraumatic ICP elevation. The role of WBC more than 6 hours after TBI should be investigated further.