Leaching as a pretreatment process to complement torrefaction in improving co-firing characteristics of Jatropha curcas seed cake

The presence of certain inorganic elements in biomass causes issues such as slagging, fouling and corrosion when co-firing with coal for power generation. In this work, the efficacy of leaching to remove these elements from Jatropha curcas seed cake was investigated. Leaching of both untorrefied and torrefied seed cakes was carried out in Milli-Q water at temperatures of 20, 35 and 50 °C. At 20 °C, the two critical elements, potassium and chlorine, decreased by as much as 85 and 97 %, respectively. Leaching at higher temperatures was only beneficial for the more intensely torrefied biomass, since they were more resistant to leaching. The electrical conductivity and ion content of the leachates were measured, as were the inorganic elemental content, dry ash content, volatile matter content and higher heating value (HHV) of the solid seed cake. A secondary benefit of the leaching was an increase in the HHV by up to 10 %

Properties of InAs quantum dots grown by molecular beam epitaxy on Ge (100)

InAs quantum dots (QDs) imbedded in a GaAs matrix grown by molecular beam epitaxy (MBE) on Ge (100) substrates have been investigated using transmission electron microscopy, photoluminescence spectroscopy, capacitance voltage spectroscopy and deep level transient spectroscopy. In comparison to a reference sample grown on GaAs (100) substrate with the same growth parameters, we observe similar QD densities, but smaller QDs with a broader size distribution on Ge substrate. This is attributed to a strained GaAs matrix in these samples

Properties of InAs quantum dots grown by molecular beam epitaxy on Ge (100)

InAs quantum dots (QDs) imbedded in a GaAs matrix grown by molecular beam epitaxy (MBE) on Ge (100) substrates have been investigated using transmission electron microscopy, photoluminescence spectroscopy, capacitance voltage spectroscopy and deep level transient spectroscopy. In comparison to a reference sample grown on GaAs (100) substrate with the same growth parameters, we observe similar QD densities, but smaller QDs with a broader size distribution on Ge substrate. This is attributed to a strained GaAs matrix in these samples

Ash Properties of Alternative Biomass

The ash behavior during suspension firing of 12 alternative solid biofuels, such as pectin waste, mash from a beer brewery, or waste from cigarette production have been studied and compared to wood and straw ash behavior. Laboratory suspension firing tests were performed on an entrained flow reactor and a swirl burner test rig, with special emphasis on the formation of fly ash and ash deposit. Thermodynamic equilibrium calculations were performed to support the interpretation of the experiments. To generalize the results of the combustion tests, the fuels are classified according to fuel ash analysis into three main groups depending upon their ash content of silica, alkali metal, and calcium and magnesium. To further detail the biomass classification, the relative molar ratio of Cl, S, and P to alkali were included. The study has led to knowledge on biomass fuel ash composition influence on ash transformation, ash deposit flux, and deposit chlorine content when biomass fuels are applied for suspension combustion. © 2009 American Chemical Society.Peer Reviewe

Electical control of a solid-state flying qubit

International audienceSolid-state approaches to quantum information technology are attractive because they are scalable. The coherent transport of quantum information over large distances is a requirement for any practical quantum computer and has been demonstrated by coupling super-conducting qubits to photons1. Single electrons have also been transferred between distant quantum dots in times shorter than their spin coherence time2,3. However, until now, there have been no demonstrations of scalable 'flying qubit' architectures--systems in which it is possible to perform quantum operations on qubits while they are being coherently transferred--in solid-state systems. These architectures allow for control over qubit separation and for non-local entanglement, which makes them more amenable to integration and scaling than static qubit approaches. Here, we report the transport and manipulation of qubits over distances of 6 mm within 40 ps, in an Aharonov-Bohm ring connected to twochannel wires that have a tunable tunnel coupling between channels. The flying qubit state is defined by the presence of a travelling electron in either channel of the wire, and can be controlled without a magnetic field. Our device has shorter quantum gates (<1 mm), longer coherence lengths (!86 mm at 70 mK) and higher operating frequencies (!100 GHz) than other solid-state implementations of flying qubit