Olivine catalysts for methane- and tar-steam reforming

The removal of tar and lower hydrocarbons is a vital technological barrier hindering the development of biomass gasification. The present work evaluates four olivine catalysts (three untreated of different origin and one calcined) for lowering the amount of these compounds in biomass derived syngas by reforming model compounds (naphthalene, toluene, and methane). Treatments prior to reaction were shown to largely impact the catalytic activity and physiochemical properties of the olivine catalysts depending on its origin. The formation of free Fe phases following decomposition of a Fe-bearing serpentine phase ((Mg,Fe)₃Si₂O₅(OH)₄) near the surface of untreated olivine catalysts proved most important for facilitating higher activity compared to olivine catalysts with little or no serpentine phase initially. The most active catalyst was efficient at naphthalene removal (90% conversion at 800 °C), but more active catalysts are needed for applications where methane removal is required. Additionally, carbon deposition during naphthalene-steam reforming as well as Fe clustering during naphthalene-steam reforming and exposure to reducing conditions suggested stability may be a liability.     

Multisegment nanowire sensors for the detection of DNA molecules

We describe a novel application for detecting specific single strand DNA sequences using multisegment nanowires via a straightforward surface functionalization method. Nanowires comprising CdTe-Au-CdTe segments are fabricated using electrochemical deposition, and electrical characterization indicates a p-type behavior for the multisegment nanostructures, in a back-to-back Schottky diode configuration. Such nanostructures modified with thiol-terminated probe DNA fragments could function as high fidelity sensors for biomolecules at very low concentration. The gold segment is utilized for functionalization and binding of single strand DNA (ssDNA) fragments while the CdTe segments at both ends serve to modulate the equilibrium Fermi level of the heterojunction device upon hybridization of the complementary DNA fragments (cDNA) to the ssDNA over the Au segment. Employing such multisegment nanowires could lead to the fabrication more sophisticated and high multispecificity biosensors via selective functionalization of individual segments for biowarfare sensing and medical diagnostics applications.     

Grain growth kinetic in xTiO2–6 wt.% Bi2O3–(94 − x) ZnO (x=0, 2, 4) ceramic system

The grain growth kinetics in the 0, 2 and 4 wt.% TiO₂ added ZnO–6 wt.% Bi₂O₃ system was studied using the simplified phenomenological grain growth kinetics equation together with the physical properties of the sintered samples. The grain growth exponent value (n) and the apparent activation energy for the ZnO–6 wt.% Bi₂O₃ system was 5 and 218 kJ/ mol, respectively. The addition of the TiO₂ to the ZnO–6 wt.% Bi₂O₃ system inhibited the ZnO grain growth. At 2 and 4 wt.% TiO₂ additions, the apparent activation energies were calculated as 467 and 346 kJ/ mol, respectively. The addition of TiO₂ to the system inhibited the grain growth of ZnO ceramics.     

Biogas Catalytic Reforming Studies on Nickel‐Based Solid Oxide Fuel Cell Anodes

Heterogeneous catalysis studies were conducted on two crushed solid oxide fuel cell (SOFC) anodes in fixed‐bed reactors. The baseline anode was Ni/ScYSZ (Ni/scandia and yttria stabilized zirconia), the other was Ni/ScYSZ modified with Pd/doped ceria (Ni/ScYSZ/Pd‐CGO). Three main types of experiments were performed to study catalytic activity and effect of sulfur poisoning: (i) CH₄ and CO₂ dissociation; (ii) biogas (60% CH₄ and 40% CO₂) temperature‐programmed reactions (TPRxn); and (iii) steady‐state biogas reforming reactions followed by postmortem catalyst characterization by temperature‐programmed oxidation and time‐of‐flight secondary ion mass spectrometry. Results showed that Ni/ScYSZ/Pd‐CGO was more active for catalytic dissociation of CH₄ at 750 °C and subsequent reactivity of deposited carbonaceous species. Sulfur deactivated most catalytic reactions except CO₂ dissociation at 750 °C. The presence of Pd‐CGO helped to mitigate sulfur deactivation effect; e.g. lowering the onset temperature (up to 190 °C) for CH₄ conversion during temperature‐programmed reactions. Both Ni/ScYSZ and Ni/ScYSZ/Pd‐CGO anode catalysts were more active for dry reforming of biogas than they were for steam reforming. Deactivation of reforming activity by sulfur was much more severe under steam reforming conditions than dry reforming; a result of greater sulfur retention on the catalyst surface during steam reforming.     

Integrated scheduling and tool management in flexible manufacturing systems

A multistage algorithm is proposed that will solve the scheduling problem in a flexible manufacturing system by considering the interrelated subproblems of processing time control, tool allocation and machining conditions optimization. The main objective of the proposed algorithm is to minimize total production cost consisting of tooling, operational and tardiness costs. The proposed integrated approach recognizes an important trade-off in automated manufacturing systems that has been largely unrecognized, and which is believed can be effectively exploited to improve production efficiency and lead to substantial cost reductions.     

Hydrophobic flocculation of talc with kerosene and effects of anionic surfactants

ABSTRACT

The variation of the hydrophobic flocculation behavior of talc mineral with pH, kerosene concentration, stirring speed, flocculation, and settling times was investigated. The experimental studies showed that the flocculation of talc suspension increased to a particular point with increasing kerosene concentration and thereafter decreased slightly. Also, the flocculation with kerosene was not much affected by the pH changes of the suspension. On the other hand, sodium oleate, sodium dodecyl sulfate (SDS), and Aero 801 used as anionic surfactant in conjunction with kerosene provided significant increases in the flocculation of talc, and depends on increasing surface hydrophobicity of the particles. Especially, in the presence of sodium oleate along with kerosene, the talc suspension could be flocculated with a recovery of 95%. Consequently, the enhancement with nonpolar oil was more significant for the hydrophobic flocculation of talc suspension promoted by long hydrocarbon chain surfactant (sodium oleate) than short hydrocarbon chain surfactants (SDS and Aero 801).     

Development of microencapsulated grape juice powders using black ‘Isabel’ grape peel pectin and application in jelly formulation with enhanced in vitro bioaccessibility of anthocyanins

In this study, pigmented pectin (grape pectin, GP) was extracted from the peels of black Isabel grapes. This highly methoxylated GP was composed mainly of galacturonic acid, arabinose, and other neutral monosaccharides. Its red color was ascribed to the anthocyanin content, and the main contribution was from malvidin-3-O-glucoside. To improve the yield and color properties of spray-dried Isabel grape juice powders, maltodextrin (MD) was substituted with this colored GP. When 25% of MD was substituted with GP, the powder yield increased from 46.0% to 60.4%, but it decreased to 21% when the substitution was 40%. GP inclusion increased the encapsulation efficiency of total anthocyanin in powders from 55.70% to 88.66%. When this spray-dried grape juice powder containing GP was utilized in a jelly recipe (4%–10%), a higher level of inclusion yielded stronger and more brittle jellies. When the jellies containing varying amounts of GP were subjected to in vitro digestion, the formulation with a higher amount of GP yielded a higher recovery of anthocyanins. In addition to being utilized as a carrier agent for spray-drying applications, this pigmented GP can also be tailored for a variety of applications, such as the development of pH-sensitive edible films and functional beverage formulations.