Photoelectrochemical water splitting: silicon photocathodes for hydrogen evolution

The development of low cost, scalable, renewable energy technologies is one of today's most pressing scientific challenges. We report on progress towards the development of a photoelectrochemical water-splitting system that will use sunlight and water as the inputs to produce renewable hydrogen with oxygen as a by-product. This system is based on the design principle of incorporating two separate, photosensitive inorganic semiconductor/liquid junctions to collectively generate the 1.7-1.9 V at open circuit needed to support both the oxidation of H_2O (or OH^-) and the reduction of H^+ (or H_2O). Si microwire arrays are a promising photocathode material because the high aspect-ratio electrode architecture allows for the use of low cost, earth-abundant materials without sacrificing energy-conversion efficiency, due to the orthogonalization of light absorption and charge-carrier collection. Additionally, the high surfacearea design of the rod-based semiconductor array inherently lowers the flux of charge carriers over the rod array surface relative to the projected geometric surface of the photoelectrode, thus lowering the photocurrent density at the solid/liquid junction and thereby relaxing the demands on the activity (and cost) of any electrocatalysts. Arrays of Si microwires grown using the Vapor Liquid Solid (VLS) mechanism have been shown to have desirable electronic light absorption properties. We have demonstrated that these arrays can be coated with earth-abundant metallic catalysts and used for photoelectrochemical production of hydrogen. This development is a step towards the demonstration of a complete artificial photosynthetic system, composed of only inexpensive, earth-abundant materials, that is simultaneously efficient, durable, and scalable

Policies and Procedures for Accessing Archived NASA Lunar Data via the Web

The National Space Science Data Center (NSSDC) was established by NASA to provide for the preservation and dissemination of scientific data from NASA missions. This paper describes the policies specifically related to lunar science data. NSSDC presently archives 660 lunar data collections. Most of these data (423 units) are stored offline in analog format. The remainder of this collection consists of magnetic tapes and discs containing approximately 1.7 TB of digital lunar data. The active archive for NASA lunar data is the Planetary Data System (PDS). NSSDC has an agreement with the PDS Lunar Data Node to assist in the restoration and preparation of NSSDC-resident lunar data upon request for access and distribution via the PDS archival system. Though much of NSSDC's digital store also resides in PDS, NSSDC has many analog data collections and some digital lunar data sets that are not in PDS. NSSDC stands ready to make these archived lunar data accessible to both the research community and the general public upon request as resources allow. Newly requested offline lunar data are digitized and moved to near-line storage devices called digital linear tape jukeboxes. The data are then packaged and made network-accessible via FTP for the convenience of a growing segment of the user community. This publication will 1) discuss the NSSDC processes and policies that govern how NASA lunar data is preserved, restored, and made accessible via the web and 2) highlight examples of special lunar data requests

Outstanding Educational Performance Awards: Highlighting High Achieving Arkansas Schools, 2010

So, in this Arkansas Education Report (AER) we aim to highlight excellent performance and give our congratulations. To that end, we are happy to highlight many high performing schools around the state in our now-annual AER entitled the Outstanding Educational Performance Awards

Outstanding Educational Performance Awards: Highlighting Top Achieving Arkansas Schools, 2009

Since our founding in 2003, the mission of the Office for Education Policy has been to look at pressing issues through the lens of academic research and disseminate our findings to educators, policymakers, and other stakeholders around Arkansas. Every once in a while, however, we think it is okay to stray from issue analysis and simply share some good news! So, in this Arkansas Education Report (AER) we merely aim to highlight excellent performance and give our congratulations. To that end, we are happy to highlight the top performing schools around the state in an annual AER entitled the Outstanding Educational Performance Awards

Component Depreciation: A Tax Planning Strategy for Small Businesses

Recent federal   court  and  Internal  Revenue  Service  (IRS)  decisions  have  opened  up  an excellent  opportunity for   both  small  and  large  businesses  to  once  again  use  component depreciation,  thus  accelerating  depreciation  deductions  and reducing  cost  of buildings and improvements  in present  value terms.   Minor changes in the design or in the procedures followed  in purchasing  a building make it possible  to shorten the depreciable lives of portions of the "building". The savings can easily exceed the additional design, construction, and bidding costs especially if the changes are minor. Small business owners,  who may  not always retain  a fulltime  tax  advisor,  should  be  aware  that  it  is  necessary  to  involve  a  tax consultant at the beginning of the design process for construction projects or early in the search for  a building purchase

IV. Fossil Fishes From The Miocene Ellensburg Formation, South Central Washington

The Ellensburg Formation was named for sediments deposited in the Kittitas Valley along the Yakima River near Ellensburg, Washington (Russell, 1893, 1900). Similar beds are present to the south along the leeward front of the emerging central Cascade Mountains; including the Nile, Selah, Yakima, and Toppenish basins. Further south along the Columbia River, portions of the Dalles Group, Rhododendron Formation, and Sandy River Mudstone are likely temporal equivalents; the latter two of which are found on the windward side of the uplifting Cascade Range (Farooqui, et al., 1981; Evarts et al., 2009).Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146545/1/MP 204vol4.pdfDescription of MP 204vol4.pdf : Main Articl

Solar Water Splitting Cells

No abstract

Low-density series expansions for directed percolation I: A new efficient algorithm with applications to the square lattice

A new algorithm for the derivation of low-density series for percolation on directed lattices is introduced and applied to the square lattice bond and site problems. Numerical evidence shows that the computational complexity grows exponentially, but with a growth factor \lambda < \protect{\sqrt[8]{2}}, which is much smaller than the growth factor \lambda = \protect{\sqrt[4]{2}} of the previous best algorithm. For bond (site) percolation on the directed square lattice the series has been extended to order 171 (158). Analysis of the series yields sharper estimates of the critical points and exponents.Comment: 20 pages, 8 figures (3 of them > 1Mb

Emplacing a cooling-limited rhyolite lava flow: similarities with basaltic lava flows

Accurate forecasts of lava flow length rely on estimates of eruption andmagma properties and, potentially more challengingly, on an understanding of the relative influence of characteristics such as the apparent viscosity, the yield strength of the flow core, or the strength of the lava’s surface crust. For basaltic lavas, the relatively high frequency of eruptions has resulted in numerous opportunities to test emplacement models on such low silica lava flows. However, the flow of high silica lava is much less well understood due to the paucity of contemporary events and, if observations of flow length change are used to constrain straightforward models of lava advance, remaining uncertainties can limit the insight gained. Here, for the first time, we incorporatemorphological observations from during and after flow field evolution to improve model constraints and reduce uncertainties. After demonstrating the approach on a basaltic lava flow (Mt. Etna 2001), we apply it to the 2011–2012 Cordón Caulle rhyolite lava flow, where unprecedented observations and syn-emplacement satellite imagery of an advancing silica-rich lava flow have indicated an important influence from the lava flow’s crust on flow emplacement. Our results show that an initial phase of viscosity-controlled advance at Cordón Caulle was followed by later crustal control, accompanied by formation of flow surface folds and large-scale crustal fractures. Where the lava was unconstrained by topography, the cooled crust ultimately halted advance of the main flow and led to the formation of breakouts from the flow front and margins, influencing the footprint of the lava, its advance rate, and the duration of flow advance. Highly similar behavior occurred in the 2001 Etna basaltic lava flow. In our comparison of these two cases, we find close similarities between the processes controlling the advance of a crystal-poor rhyolite and a basaltic lava flow, suggesting common controlling mechanisms that transcend the profound rheological and compositional differences of the lavas