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University of Arkansas, Fayetteville

2012

Journal of the Arkansas Academy of Science

Articles 1 - 11 of 11

Full-Text Articles in Physical Sciences and Mathematics

Impervious Surface Area Change In Arkansas From 2001 To 2006, D. E. Long Ii, R. C. Weih Jr. Jan 2012

Impervious Surface Area Change In Arkansas From 2001 To 2006, D. E. Long Ii, R. C. Weih Jr.

Journal of the Arkansas Academy of Science

Impervious Surface Area (ISA) is a measurement used to determine stream quality as well as urban sprawl. ISA was calculated as part of the National Land Cover Dataset (NLCD) using Landsat imagery by the Multi-Resolution Land Characteristics Consortium (MRLC) in both 2001 and 2006. ISA for each of the 75 counties in Arkansas was taken from the NLCD for both 2001 and 2006. Using the ISA data, percent imperviousness was determined for each county in each time period as well as the difference between the two periods. These data were also compared to census projections for the two time periods …

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Synthesis And Optical Properties Of Sprayed Zno And Zno:Ga Thin Films, N. F. Habubi, S. S. Chiad, S. Jabbar, W. Jabbar Jan 2012

Synthesis And Optical Properties Of Sprayed Zno And Zno:Ga Thin Films, N. F. Habubi, S. S. Chiad, S. Jabbar, W. Jabbar

Journal of the Arkansas Academy of Science

Characteristics and optical constants of pure and Ga-doped ZnO thin films have been studied. Pure and Ga-doped zinc oxide thin films were deposited onto glass substrates using the spray pyrolysis technique. Optical absorption studies in the wavelength range of 300–900 nm showed a peak near 450 nm for different doped films (in addition to the peak for un-doped ZnO). Increasing the doping concentration of Ga to 7% induced an increase in the optical constants of films. This increase is attributed to the formation of chargetransfer complexes. ZnO thin films doped with Ga have improved the optical transmittance in the visible …

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Fabrication And Characterization Of Aluminum-Doped Zno/Pani Hybrid Solar Cells, S. Abdulalmohsin, S. M. Al-Mutoki, Z. Li Jan 2012

Fabrication And Characterization Of Aluminum-Doped Zno/Pani Hybrid Solar Cells, S. Abdulalmohsin, S. M. Al-Mutoki, Z. Li

Journal of the Arkansas Academy of Science

We report a facile method to fabricate an AZO/PANI heterostructure by a sandwiching technique. Aluminum-doped ZnO (AZO) films were deposited onto indium tin oxide (ITO) glass using the sputtering technique while PANI films were deposited onto ITO glass using electropolymerization. The optoelectric properties of the inorganic/organic device were characterized

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Interacting Dark Energy Models And The Cosmic Coincidence Problem, H. Shojaei, C. Smith, D. Waters Jan 2012

Interacting Dark Energy Models And The Cosmic Coincidence Problem, H. Shojaei, C. Smith, D. Waters

Journal of the Arkansas Academy of Science

Interacting dark energy models have been employed to study the behavior of dark energy and matter in the presence of an interaction between the two. One of the successful aspects of these models is how they explain the cosmic coincidence problem. In this work we consider a specific interaction to study the behavior of dark energy and matter through the history of evolution.

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Current Range In Lightning Return Strokes, M. Hemmati, W. P. Childs, D. C. Waters, J. R. Christensen, B. C. Richard Jan 2012

Current Range In Lightning Return Strokes, M. Hemmati, W. P. Childs, D. C. Waters, J. R. Christensen, B. C. Richard

Journal of the Arkansas Academy of Science

In our investigation of breakdown waves, we use a one-dimensional, steady-state, constant velocity fluid model. This investigation involves breakdown waves for which the electric field force on electrons is in the opposite direction of wave propagation. The waves are considered to be shock fronted and the electron gas partial pressure is large enough to sustain the wave propagation. Our basic set of electron fluid-dynamical equations is composed of the equations for conservation of mass, momentum and energy, coupled with Poisson’s equation. This investigation involves breakdown waves for which a large current exists behind the shock front. The current behind the …

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Establishing Baseline Nutrient And Sediment Input In The Lower Cache River Watershed, Ar, A. M. Gilmer, C. A. Rosado-Berrios, J. L. Bouldin Jan 2012

Establishing Baseline Nutrient And Sediment Input In The Lower Cache River Watershed, Ar, A. M. Gilmer, C. A. Rosado-Berrios, J. L. Bouldin

Journal of the Arkansas Academy of Science

Contaminants in waterways continue to be a problem especially in watersheds dominated by land use changes such as agriculture. Clearing the land for agricultural use is needed to support the population; however, agricultural contaminants are cited as contributing the greatest input of suspended solids and nutrients to waterways. Quantifying various contaminants in surface water is useful in determining their origin, thus aiding in their mitigation. This study, focused on the Cache River Watershed, reports pH, dissolved oxygen (DO), conductivity, turbidity, total suspended solids (TSS), NO3 - , NO2 - , and PO4 3- in the lower sub watersheds. It was …

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Electrochemical Polymerization Of Ppy-Mwcnt Composite As A Counter Electrode For Dye-Sensitized Solar Cells, S. Abdulalmohsin, S. M. Al-Mutoki, Z. Li Jan 2012

Electrochemical Polymerization Of Ppy-Mwcnt Composite As A Counter Electrode For Dye-Sensitized Solar Cells, S. Abdulalmohsin, S. M. Al-Mutoki, Z. Li

Journal of the Arkansas Academy of Science

Polypyrrole (PPy) - multi wall carbon nanotube (MWCNT) nanocomposites were synthesized by using in situ electrochemical polymerization with different COOH-functionalized MWCNTs. The PPY-MWCNT composites were used as counter electrode in the fabrication of dye sensitized solar cells (DSCs). Compared to the DSC device with PPy counter electrode, the devices with PPY/MWCNT composite electrode offer much higher total photovoltaic conversion efficiency due to the reduced series resistance. These PPY/MWCNT nanocomposite materials proved to be a good alternate to the expensive Pt as counter electrode in DSC.

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Comparing Methods For Interpolation To Improve Raster Digital Elevation Models, J. C. Guarneri, R. C. Weih Jr. Jan 2012

Comparing Methods For Interpolation To Improve Raster Digital Elevation Models, J. C. Guarneri, R. C. Weih Jr.

Journal of the Arkansas Academy of Science

Digital elevation models (DEMs) are available as raster files at 100m, 30m, and 10m resolutions for the contiguous United States and are used in a variety of geographic analyses. Some projects may require a finer resolution. GIS software offers many options for interpolating data to higher resolutions. We compared ten interpolation methods using 10m sample data from the Ouachita Mountains in central Arkansas. We interpolated the 10m DEM to 5m, 2.5m, and 1m resolutions and compared the absolute mean difference (AMD) for each using surveyed control points. Overall, there was little difference in the accuracy between interpolation methods at the …

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Characterization Of Temporal And Spatial Variation In Subwatersheds Of The Strawberry River, Ar, Prior To Implementation Of Agricultural Best Management Practices, T. R. Brueggen-Boman, J. L. Bouldin Jan 2012

Characterization Of Temporal And Spatial Variation In Subwatersheds Of The Strawberry River, Ar, Prior To Implementation Of Agricultural Best Management Practices, T. R. Brueggen-Boman, J. L. Bouldin

Journal of the Arkansas Academy of Science

Benthic macroinvertebrate (BMI) assessments indicate alterations in physical and/or chemical factors making them valuable tools when attempting to assess agricultural best management practices (BMPs). The purpose of this study was to obtain pre-BMP land cover and macroinvertebrate community data in order to characterize temporal and spatial variation in three catchments: Little Strawberry (LS), Greasy Creek (GC), and Sandy Creek (SC) of the Strawberry River Watershed, located in north central Arkansas, in order to establish baseline conditions. BMIs were collected for the three subwatersheds in 1995, 1999, 2002, 2003 and 2009. Taxa richness, Hilsenhoff Biotic Index (HBI) and Ephemeroptera, Plecoptera and …

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Al/Pani-Mwnt/Au-Plastic Schottky Diode Solar Cells, S. Abdulalmohsin, S. M. Al-Mutoki, Z. Li Jan 2012

Al/Pani-Mwnt/Au-Plastic Schottky Diode Solar Cells, S. Abdulalmohsin, S. M. Al-Mutoki, Z. Li

Journal of the Arkansas Academy of Science

Al/PANI-MWNT/Au-Plastic Schottky diode solar cells were fabricated by the electrochemical polymerization technique to make polyaniline films on the top of gold nanoparticles film. The aluminum contact was deposited by thermal evaporation. The electro-optical characteristics of these devices produced at the different polymerization time were compared. Here, we achieved the highest ever reported open-circuit voltage of 0.8 V with the electrochemical polymerization technique. The polymerization of polyaniline films was thought to be a major factor in the enhanced performance. The effects of varying the polyaniline thickness on the device performance were investigated

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In Memoria: Art Fry, 1921-2011, Collis Geren Jan 2012

In Memoria: Art Fry, 1921-2011, Collis Geren

Journal of the Arkansas Academy of Science

No abstract provided.

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