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Ozin G.A.,Group Solar
Advanced Materials | Year: 2015

While the chemical energy in fossil fuels has enabled the rapid rise of modern civilization, their utilization and accompanying anthropogenic CO2 emissions is occurring at a rate that is outpacing nature's carbon cycle. Its effect is now considered to be irreversible and this could lead to the demise of human society. This is a complex issue without a single solution, yet from the burgeoning global research activity and development in the field of CO2 capture and utilization, there is light at the end of the tunnel. In this article a couple of recent advances are illuminated. Attention is focused on the discovery of gas-phase, light-assisted heterogeneous catalytic materials and processes for CO2 photoreduction that operate at sufficiently high rates and conversion efficiencies, and under mild conditions, to open a new pathway for an energy transition from today's "fossil fuel economy" to a new and sustainable "CO2 economy". Whichever of the competing CO2 capture and utilization approaches proves to be the best way forward for the development of a future CO2-based solar fuels economy, hopefully this can occur in a period short enough to circumvent the predicted adverse consequences of greenhouse gas climate change. The future is bright for the transformation of sunlight into renewable solar fuels that can sustain civilization. Recent advances that focus on the discovery of gas-phase, light-assisted, heterogeneous catalytic materials and processes for CO2 photo-reduction that operate at sufficiently high rates and conversion efficiencies to facilitate an energy transition from today's unsustainable "fossil fuel economy" to a new and sustainable "CO2 economy" are highlighted. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Aggarwal M.,Group Solar
Advances in Space Research | Year: 2011

Monthly median values of hourly total electron content (TEC) is obtained with GPS at a station near northern anomaly crest, Rajkot (geog. 22.29°N, 70.74°E; geomag. 14.21°N, 144.9°E) to study the variability of low latitude ionospheric behavior during low solar activity period (April 2005 to March 2006). The TEC exhibit characteristic features like day-to-day variability, semiannual anomaly and noon bite out. The observed TEC is compared with latest International Reference Ionosphere (IRI) - 2007 model using options of topside electron density, NeQuick, IRI01-corr and IRI-2001 by using both URSI and CCIR coefficients. A good agreement of observed and predicted TEC is found during the daytime with underestimation at other times. The predicted TEC by NeQuick and IRI01-corr is closer to the observed TEC during the daytime whereas during nighttime and morning hours, IRI-2001 shows lesser discrepancy in all seasons by both URSI and CCIR coefficients. © 2011 COSPAR. Published by Elsevier Ltd. All rights reserved.


An electrically heated deposition cartridge for use in the production of materials via the chemical vapor deposition process that has (i) a higher ratio of surface area to volume than a seed rod pair, (ii) a higher ratio of starting effective deposition surface area to final effective deposition surface area than a seed rod pair, and (iii) a higher ratio of effective deposition surface area to gross surface area than a basic deposition plate, which are achieved by reaching and maintaining the desired temperatures on all desired surfaces of the deposition cartridge, which in turn is achieved by distribution of the desired amount of current through all desired cross-sectional areas of the deposition cartridge.


Methods are provided for casting one or more of a semi-conductor, an oxide, and an intermetallic material. With such methods, a cast body of a geometrically ordered multi-crystalline form of the one or more of a semiconductor, an oxide, and an intermetallic material may be formed that is free or substantially free of radially-distributed impurities and defects and having at least two dimensions that are each at least about 10 cm.


The present invention overcomes the limitations of Siemens reactors by providing for the deposition reaction to occur inside of a sealed crucible rather than inside of the overall cavity of a water-cooled reactor. The crucible itself is positioned inside of a cartridge reactor, which can have heat shields between crucible and the reactor walls to significantly reduce radiant energy losses. Additionally, the ratio of deposition surface area to cavity volume in the crucible is much higher than that in the ratio of rod deposition surface area to overall cavity volume in Siemens reactors, which results in a much higher contact percentage of gas molecules with the deposition surfaces. This in turn results in a much higher actual conversion ratio of material in the gas to material on the deposition surfaces.

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