Oxometalate-glass composites and thin films

New glass-composites with ion exchange properties have been developed. Ammonium 12-molybdophosphate (AMP) (ΝΗ4)3ΡΜοΐ2θ4ο, and ammonium 12-tungstophosphate (AWP) (Nh4)3PW12O40, known for their ion exchange capabilities, are included either in preformed aerogels with defined pore size, or are added to sol-gel mixtures during the process of gel formation. Characterization is carried out by FTIR, Raman and EXAFS spectroscopy. Ion exchange capacities for the oxometalate precursors are determined for silver and rubidium and are compared to those of the glass composites. Glass composites show high ion exchange capacity, but some portion of the metalate complexes leaches from the glass during the procedure. This is in contrast to thin composite films, which have almost no porosity and do not show loss of metalate. EXAFS spectroscopy demostrates that the oxometalate microstructure is maintained in glass composites and that rubidium ions after ion exchange in glasses occupy similar cation positions as in the precursor compounds

Uniformity of the pseudomagnetic field in strained graphene

We present a study on the uniformity of the pseudomagnetic field in graphene as a function of the relative orientation between the graphene lattice and straining directions. For this, we strained a regular micron-sized graphene hexagon by deforming it symmetrically by displacing three of its edges. By simulations, we found that the pseudomagnetic field is strongest if the strain is applied perpendicular to the armchair direction of graphene. For a hexagon with a side length of 1 ${\rm \mu}$m, the pseudomagnetic field has a maximum of 1.2 T for an applied strain of 3.5% and it is uniform (variance $< 1$%) within a circle with a diameter of $\sim 520$ nm. This diameter is on the order of the typical diameter of the laser spot in a state-of-the-art confocal Raman spectroscopy setup, which suggests that observing the pseudomagnetic field in measurements of shifted magneto-phonon resonance is feasible.Comment: 7 pages, 5 figure

A possible radiation-resistant solar cell geometry using superlattices

A solar cell structure is proposed which uses a GaAs nipi doping superlattice. An important feature of this structure is that photogenerated minority carriers are very quickly collected in a time shorter than bulk lifetime in the fairly heavily doped n and p layers and these carriers are then transported parallel to the superlattice layers to selective ohmic contacts. Assuming that these already-separated carriers have very long recombination lifetimes, due to their across an indirect bandgap in real space, it is argued that the proposed structure may exhibit superior radiation tolerance along with reasonably high beginning-of-life efficiency

Nanoporous silica-based protocells at multiple scales for designs of life and nanomedicine.

Various protocell models have been constructed de novo with the bottom-up approach. Here we describe a silica-based protocell composed of a nanoporous amorphous silica core encapsulated within a lipid bilayer built by self-assembly that provides for independent definition of cell interior and the surface membrane. In this review, we will first describe the essential features of this architecture and then summarize the current development of silica-based protocells at both micro- and nanoscale with diverse functionalities. As the structure of the silica is relatively static, silica-core protocells do not have the ability to change shape, but their interior structure provides a highly crowded and, in some cases, authentic scaffold upon which biomolecular components and systems could be reconstituted. In basic research, the larger protocells based on precise silica replicas of cells could be developed into geometrically realistic bioreactor platforms to enable cellular functions like coupled biochemical reactions, while in translational research smaller protocells based on mesoporous silica nanoparticles are being developed for targeted nanomedicine. Ultimately we see two different motivations for protocell research and development: (1) to emulate life in order to understand it; and (2) to use biomimicry to engineer desired cellular interactions

The Institutional and Social Integration of Child Asylum-Seekers in the Schools and Society of the Canton of Vaud, Switzerland

As an increasing number of asylum-seekers cross the border into Switzerland in search of protection, Switzerland faces the challenge of accommodating and integrating asylum populations into society while protecting all basic human rights. This study looks at the reception of child asylum-seekers in the canton of Vaud, Switzerland in terms of their integration in the education system and society. A series of interviews and a literature review were used to identify what services are available to child asylumseekers both at school and within the canton that may facilitate integration. The findings of this study indicate that child asylum-seekers are receiving equal access to education in the compulsory school system and that the canton is providing “classes d’accueil” (integration classes) as well as numerous social services to assist with the integration of child asylum-seekers. However, the results of the study also evidence structural and societal barriers to the integration of asylum-seekers in Switzerland, which calls for the reevaluation of the asylum policies in regards to the rights of children, as well as for the need of additional research in this area

New directions in InP solar cell research

Recent research efforts representing new directions in InP solar cell research are reviewed. These include heteroepitaxial growth on silicon and gallium arsenide substrates, V-grooved cells, large area high efficiency cells, and surface passivation. Improvements in heteroepitaxial cell efficiency are described together with processing of 19.1 percent, 4 sq cm cells. Recommendations are made for improvements in processing leading to increased efficiencies

Cross-Hedging Distillers Dried Grains: Exploring Corn and Soybean Meal Futures Contracts

Ethanol mandates and high fuel prices have led to an increase in the number of ethanol plants in the U.S. in recent years. In turn, this has led to an increase in the production of distillers dried grains (DDGs) as a co-product of ethanol production. DDG production in 2006 is estimated to be near 11 million tons. A sharp increase in ethanol production and thus DDGs is expected in 2007 with an increase with the number of ethanol plants. As with most competitive industries, there is some level of price risk in handling DDGs and no futures contract available for this co-product. Ethanol plants, as well as users of DDGs, may find cross-hedging DDGs with corn or soybean meal (SBM) futures as an effective means of managing risk. Traditionally, DDGs are hedged using only corn futures.

Cross-Hedging Distillers Dried Grains Using Corn and Soybean Meal Futures Contracts

Ethanol mandates have led to an increase in the production of distillers dried grains (DDGs), a co-product of ethanol production that is incorporated into livestock rations. As with most competitive industries, there is some level of price risk in handling DDGs, and there is no DDG futures contract available for managing price risk. Commonly, DDGs are hedged using only corn futures. Our results suggest that cross-hedge risk may be reduced by including soybean meal futures in an encompassing cross-hedge strategy. Further, we also conclude soybean meal futures currently may be slightly more effective at reducing risk than in the past.cross-hedge, distillers dried grains, ethanol, price risk, Agribusiness, Demand and Price Analysis,

Radiation damage and annealing in large area n+/p/p+ GaAs shallow homojunction solar cells

Annealing of radiation damage was observed for the first time in VPE-grown, 2- by 2-cm, n+/p/p+ GaAs shallow homojunction solar cells. Electrical performance of several cells was determined as a function of 1-MeV electron fluence in the range of 10 to the 13th power to 10 to the 15th power e-/sq cm and as a function of thermal annealing time at various temperatures. Degradation of normalized power output after a fluence of 10 to the 15th power 1-MeV electrons/sq cm ranged from a low of 24 to 31 percent of initial maximum power. Normalized short circuit current degradation was limited to the range from 10 to 19 percent of preirradiated values. Thermal annealing was carried out in a flowing nitrogen gas ambient, with annealing temperatures spanning the range from 125 to 200 C. Substantial recovery of short circuit current was observed at temperatures as low as 175 C. In one case improvement by as much as 10 percent of the postirradiated value was observed. The key features of these cells are their extremely thin emitter layers (approxmately 0.05 micrometers), the absence of any Al sub xGd sub 1-x As passivating window layer, and their fabrication by vapor phase epitaxy