Reduction Behaviour of Wüstite Doped with MgO

Compacts made from pure wüstite and compacts doped with 2% MgO were annealed at 1000°C for 3 hrs in 50%CO‐CO₂ gas mixtures. The annealed samples were isothermally reduced at 800‐1100°C in H₂ gas. Selected samples were isothermally reduced at 1000°C with pure CO and 50%H₂‐CO gas mixture to investigate the effect of gas composition on the reduction processes. The oxygen weight loss resulting from the reduction of the samples was recorded as a function of time. X‐ray diffraction (XRD), scanning electron microscopy (SEM), optical microscopy and porosity measurements were used to characterize the annealed and reduced samples. Magnesio‐wüstite (MgO·FeO) phase was formed during the annealing of MgO doped wüstite. The MgO·FeO in turn decreased the porosity of the annealed doped samples compared to pure wüstite compacts. The influence of temperature, gas composition and MgO content on the reduction behaviour and the morphology of the annealed samples was investigated. The values of the apparent activation energy were calculated from Arrhenius plots and correlated with the reduction mechanism. The reduction rate increased with reaction temperature. In doped compacts, the MgO·FeO phase was not completely reduced both at lower reduction temperature (800°C) and during reduction with pure CO. From the activation energy values, the initial reaction stage was controlled by the combined effect of chemical reaction and gas diffusion while solid state diffusion controlled the final stage of reduction. Morphologically, metallic iron was formed in different shape structures under the effect of MgO addition and reduction conditions.     

Fine‐Tuning of Yellow or Red Photo‐ and Electroluminescence of Functional Difluoro‐boradiazaindacene Films

The present work describes the synthesis of difluoro‐boradiazaindacenes (Bodipy) functionalized at the central 8‐position by phenylamino moieties easily transformable into phenyl amide scaffoldings. Molecules carrying three linear or branched chains were prepared and characterized. An X‐ray crystal structure for the pivotal trimethoxyphenyl‐Bodipy derivative was determined, and the packing is discussed in terms of molecular interactions; a key feature for the formation of thin films. All of the dyes are thermally stable up to 170 °C but no liquid‐crystalline phases are observed. Reversible reduction and oxidation processes occur around +0.97 and −1.34 V, respectively, versus saturated calomel electrode in solution and the electroactivity and photoluminescence are maintained in thin films produced by vacuum evaporation. Interestingly, two distinct emissions are observed at 550 and 635 nm by electroluminescence of the trimethoxyphenyl‐Bodipy derivative, corresponding to the luminescence of isolated molecules and dimers, respectively. Doping Alq₃ films with this Bodipy molecule by vacuum evaporation produces organic light‐emitting diodes (OLEDs) in which very efficient energy transfer from the Alq₃ matrix to the Bodipy occurs by a resonance mechanism involving the first Bodipy excited state. Yellow light (550 nm, 344 cd m⁻² at 15 V) is emitted at low doping concentration (7 mol %), whereas red light (635 nm, 125 cd m⁻² at 15 V) is emitted at higher concentration (19 mol %). Dispersion of the Bodipy into a fluorescent poly(N‐vinylcarbazole) polymer (PVK) (≈3 mol % per repeating unit of PVK) by solution processing exclusively produces yellow emission owing to the isolated Bodipyfluorophore (550 nm, 213 cd m⁻² at 15 V). The second excited state of the Bodipy dye is likely involved during energy transfer from the PVK matrix.     

Synthesis and Electrochemical Investigation of Oligomeric and Polymeric Ferrocenyl-Amides having Cyclohexyl,Phenylene, and Lysyl Spacers

This paper discusses the synthesis and characterization of a series of ferrocene oligo- and polyamides having phenylene, cyclohexyl, or lysyl spacer groups separating the electroactive ferrocene groups. The oligomeric materials are characterized by spectroscopic means and display an electrochemical signature indicating very limited electronic communication between the ferrocenes. The ferrocene-phenylene polymer however, shows clear indications of weak electronic interactions. This article is dedicated to Professor Astruc.     

Research Publication Trends and Topics in Computing in Civil Engineering

This paper provides a historical perspective on computing research in civil engineering, as reflected in the Journal of Computing in Civil Engineering (JCCE). The paper reports the results of a 17 year analysis of the Journal from 1987 through 2003. The main computing topical content as well as the origin and distribution of research sources and dissemination venues are summarized. The JCCE is intended to be of interest to researchers, professionals, and students in all civil engineering disciplines. This paper is intended to shed light on its content.     

Environmental impacts of the mega desalination project: the Red–Dead Sea conveyor

The Dead Sea is the lowest point on the earth. Historically, its level was 392 m below sea level. Due to the diversion of the water that is feeding the sea from the north and to the construction of industrial facilities in the south to extract minerals, the Dead Sea level nowadays has been lowered to 417 m. Furthermore, the surface area of the sea has been reduced from 940 km² in 1960s to 637 km² today.

In an attempt to restore the Dead Sea to its original level, and to find a reliable source of fresh water in the region which suffers from chronic water scarcity, the Red Dead Sea conveyor (RDSC) project has been proposed. RDSC would convey seawater from the Red Sea (Gulf of Aqaba) to the Dead Sea to save it from vanishing, and to produce desalinated water and hydroelectric power by utilizing the difference in elevations between the Red and Dead seas.

The proposed project is expected to have great impact on the regional socio-economic development. However, many questions need to be answered before proceeding with such a mega project. Some of the answers needed are related to the environmental impacts of the project. The present paper is an attempt to address the major environmental impacts associated with the implementation of the RDSC project. Both positive and negative impacts were considered in the analysis.

The analysis revealed that brine reject is the main adverse environmental problem. The amount of brine has been estimated to be 1050 MCM/y. In addition to salt content, the reject brine contains several chemical additives, chemical cleaning solutions and pretreatment chemicals that are discharged with the brine. Another significant adverse impact that is identified is the impact on the fragile marine environment of the Gulf of Aqaba. The semi enclosed nature of this marine environment, which encourages its unique biological diversity, also makes it particularly susceptible to pollution. Therefore, measures that should be taken during the construction and operation of the project to protect the marine environment were recommended.     

Deflagration-to-detonation transition in natural gas–air mixtures

The gas explosion test facility (GETF) previously used to study detonability of natural gas (NG)–air mixtures was modified for studies of flame acceleration and deflagration-to-detonation transition (DDT). The 73-m-long by 1.05-m-diameter tube was equipped with 15 baffles of varying blockage ratio (BR) = 0.13, 0.25, or 0.50, placed near the closed end of the tube and spaced 1.52-m apart. The remaining part of the tube was smooth. Experiments used mixtures between 5.1% and 15.0% NG–air.     

Gamma irradiation of treated waste rubber powder and its composites with waste polyethylene

This investigation was undertaken to prepare composites of waste polyethylene (WPE) with concentrations of 5, 15, and 25 wt% of waste rubber powder (WRP) and to determine the changes in properties of these composites before and after treatment of the WRP with acrylic acid. Mechanical, physical, thermal, FTIR, and SEM investigations showed that treated and gamma‐irradiated WRPs gave better properties than untreated ones. Hence, a simple method to prepare composites based on recycled polyethylene and waste rubber powder could be achieved without using expensive treatment of the polymeric wastes. J. VINYL ADDIT. TECHNOL., 2011. © 2011 Society of Plastics Engineers     

Molecular modeling and electrochemical investigations of the corrosion inhibition of nickel using some thiosemicarbazone derivatives

A relationship between molecular structures of three thiosemicarbazone derivatives and their inhibition capability was studied using electrochemical measurements (potentiodynamic polarization and EIS), molecular dynamics method and quantum chemical calculations. Electrochemical measurements results revealed that the inhibition efficiencies increased with the concentration of inhibitors. The molecular dynamic method results showed that the higher binding energy between the inhibitor and metal surface, the higher the adsorption energy and the higher the inhibition efficiency. Thiosemicarbazone derivatives have been simulated as adsorbate on Ni(111) substrate and the adsorption density, adsorption energy and binding energy have been identified on nickel surface.     

Digital holographic interferometry: Optomechanical properties of fibers

Studying polymer fiber's mechanical properties leads to an increased understanding of the behavior of polymeric structures. This will support the design of new synthetic fibers with improved properties. Thus, there is great interest in the exact knowledge of these properties. In this work, phase‐shifting digital holographic interferometry is used to investigate the variation of the optical properties of drawn polyvinylidene fluoride (PVDF) fiber. The study shows that the refractive index for light which is polarized in parallel direction to the fiber axis increases as the draw ratio increases. This implicates that the molecules become more oriented in this direction. However, the decrease in the values of the refractive index for light polarized perpendicular to the drawing direction reflects the reduced orientation of the molecules in this direction. This has been confirmed by studying the variation of the molecular orientation versus birefringence of the drawn PVDF fiber. Holograms and their relationship with the optomechanical parameters obtained are given for illustration. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers