The production of fuels and chemicals in the new world: critical analysis of the choice between crude oil and biomass vis-à-vis sustainability and the environment

Clean Technologies and Environmental Policy - Energy and the environment are intimately related and hotly debated issues. Today’s crude oil-based economy for the manufacture of...     

Dielectric Behavior and Magnetoelectric Effect in Ni0.75Co0.25Fe2O4 + Ba0.8Pb0.2TiO3 ME Composites

Magnetoelectric composites with ferrite + ferroelectric compositions xBa_0.8Pb_0.2TiO₃ + (1 – x) Ni_0.75Co_0.25Fe₂O₄ in which x varies as 0, 0.55, 0.70, 0.85 and 1.0 were prepared by ceramic method. X-ray analysis confirms single-phase formation in x = 0 and x = 1 compositions, whereas the presence of both phases is shown in x = 0.55, 0.70 and 0.85 compositions. Variation of dielectric constant () with temperature and frequency has been studied. All the samples have show linear magnetoelectric conversion in the presence of static magnetic field. Static magnetoelectric conversion factor, (dE/dH), was measured as a function of magnetic field in the samples with x = 0.55, 0.70 and 0.85 compositions. The maximum value of dE/dH was found to be 140 V/cm/Oe for x = 0.85 composition.     

Integrated atom density measurement in a zirconium atomic beam generated using a high-power strip electron beam source by diode laser absorption technique

Strip electron guns, capable of generating two-dimensional (length?width) evaporating sources, are used for the application of electron beam assisted physical vapour deposition to metallurgical coating of large substrates. The collisional relaxation processes in the atomic vapour generated using such a 2D-source differ significantly from those in a point source created using axisymmetric electron gun. In order to study the influence of collision processes, an atomic beam of zirconium was generated using a 130- mm-strip electron gun and its ground electronic state population was measured in a given optical path length using a tunable diode laser based on-line absorption spectroscopic technique. These measurements were carried out as a function of vertical height from the source (114 mm×6 mm) and for different source temperatures obtained by varying electron beam powers in the range of 40-91 kW.While the experimental values of integrated atom number density were observed to match very closely with those given by reported vapour flow model at low evaporating source temperatures, they showed significant deviation at high temperatures. The results are interpreted in terms of the collisional processes in the vapour stream and indicative of the fact that the vapour expansion from 2D source never runs out of collisions.     

Porous microspheres as additives in lead–acid batteries

The theoretical specific energy of the lead/acid battery is 176 W h kg⁻¹. The specific energy actually achieved depends on the discharge rate but is typically only about 15–25% of this maximum value. The major reason for the lead acid battery's inability to obtain higher specific energies is that much of the active material in both the positive and negative electrode is not discharged. This is especially true at the higher discharge rates where the diffusion of sulfate ions into the positive plate limits the reaction. Porous, hollow, glass microspheres (PHGM) would allow for more electrolyte storage in the electrodes and enhance the high rate energy storage of lead acid batteries. In this paper, we present a method for making hollow, glass microspheres (HGMs) porous. Presently our process only produces small yields. We believe in the future that the yields with our process can be substantially increased. PHGMs could substantially improve the high rate performance of lead acid batteries and make these batteries more attractive for hybrid electric vehicle applications.     

Presence of Potential G-Quadruplex RNA-Forming Motifs at the 5′-UTR of PP2Acα mRNA Repress Translation

RNA G-quadruplex (G4)-forming motifs present at the 5′-UTR of the protein phosphatase (PP2Ac) gene are the regulatory targets of the fragile X mental retardation protein (FMRP), which is weakly expressed in Fragile X patients. Herein, we report that the existence of such G4-forming sequence represses the translation of the PP2Acα gene. This study opens therapeutic avenues to design small molecule ligands that mimic the function of the FMRP.     

Linear Hygrothermal Viscoelastic Characterization of Nafion NRE 211 Proton Exchange Membrane

The tensile relaxation modulus of a commercially available proton exchange membrane, Nafion® NRE 211, was obtained over a range of humidity levels and temperatures using a commercial dynamic mechanical analyzer (DMA). Hygral stress relaxation master curves were first constructed, followed by a hygrothermal master curve using the time temperature moisture superposition principle. The hygrothermal master curve was fitted using a 10‐term Prony series and validated using longer term stress relaxation tests. To validate the results from the stress relaxation experiments, short and long‐term creep compliance was converted into stress relaxation modulus using a well‐known viscoelastic conversion formula, and compared with the relaxation modulus obtained under identical conditions. Good agreement was found between the two datasets. It was evident that relaxation data at 2% RH at the test temperatures was not superposable with the master curves obtained at higher relative humidity (10% < RH < 90%) at the temperature range 70 °C < T < 90 °C. It was observed that the longer term relaxation modulus under humid conditions matched well with the hygrothermal master curve; however, the longer term relaxation modulus under dry conditions was significantly higher than the relaxation master curve obtained under dry conditions, raising the possibility of a physical aging process in the ionomer and/or irreversible morphological changes in the membrane under dry conditions.     

A model for fault-tolerant networked control system using TTP/C communication

Safety-critical aerospace functions are generally required to have failure rates less than 10/sup -9/ per hour (FAA, 1988) and an architecture that supports several such functions is required to have failure rates less than 10/sup -10/ per hour. Although the requirement for an individual automobile may be more relaxed, similar requirements apply for automobiles in general (Rushby, 2001), because of their large number as compared to aircraft. Consumer-grade electronics have failure rates that are orders of magnitude worse than this. Hence, redundancy to improve failure rates and fault tolerance to prevent faults from propagating both are essential elements of a safety critical networked control system (NCS). TTP/C is a member of the time-triggered protocol (TTP) family that satisfies Society of Automotive Engineers Class C requirements for hard real-time fault-tolerant communication. A model is presented for a fault-tolerant NCS using TTP/C communication. Appropriate features of TTP/C are incorporated in the model. A simulation is presented for the electric power steering node with switching controller, which makes the node tolerant to the parameter faults column.     

Transformation of mechanically alloyed Nb-Sn powder to Nb<Subscript>3</Subscript>Sn

Nb₃Sn was processed via mechanical alloying (MA). The powder mixture comprised of stoichiometric proportions of elemental niobium and tin powder was mechanically alloyed for 3 hours and the mechanically alloyed powder mixture was heat treated. While MA resulted in Nb-Sn solid solution, the reaction leading to the formation of Nb₃Sn occurs during the subsequent heat treatment of the powder mixture.