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Faculty Publications

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2016

Articles 1 - 9 of 9

Full-Text Articles in Physical Sciences and Mathematics

Sources, Distributions And Dynamics Of Dissolved Organic Matter In The Canada And Makarov Basins, Yuan Shen, Ronald Benner, Lisa L. Robbins, Jonathan G. Wynn Oct 2016

Sources, Distributions And Dynamics Of Dissolved Organic Matter In The Canada And Makarov Basins, Yuan Shen, Ronald Benner, Lisa L. Robbins, Jonathan G. Wynn

Faculty Publications

A comprehensive survey of dissolved organic carbon (DOC) and chromophoric dissolved organic matter (CDOM) was conducted in the Canada and Makarov Basins and adjacent seas during 2010–2012 to investigate the dynamics of dissolved organic matter (DOM) in the Arctic Ocean. Sources and distributions of DOM in polar surface waters were very heterogeneous and closely linked to hydrological conditions. Canada Basin surface waters had relatively low DOC concentrations (69 ± 6 μmol L−1), CDOM absorption (a325: 0.32 ± 0.07 m−1) and CDOM-derived lignin phenols (3 ± 0.4 nmol L−1), and high spectral slope values (S275–295: 31.7 ± …

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Fulleretic Well-Defined Scaffolds: Donor–Fullerene Alignment Through Metal Coordination And Its Effect On Photophysics, Derek E. Williams, Ekaterina A. Dolgopolova, Danielle C. Godfrey, Evgeniya D. Ermolaeva, Perry J. Pellechia Dr., Andrew B. Greytak Prof. Dr., Mark Smith Dr., Stanislav M. Avdoshenko, Dr., Alexey A. Popov Dr., Natalia B. Shustova Prof. Dr. Jul 2016

Fulleretic Well-Defined Scaffolds: Donor–Fullerene Alignment Through Metal Coordination And Its Effect On Photophysics, Derek E. Williams, Ekaterina A. Dolgopolova, Danielle C. Godfrey, Evgeniya D. Ermolaeva, Perry J. Pellechia Dr., Andrew B. Greytak Prof. Dr., Mark Smith Dr., Stanislav M. Avdoshenko, Dr., Alexey A. Popov Dr., Natalia B. Shustova Prof. Dr.

Faculty Publications

Herein, we report the first example of a crystalline metal–donor–fullerene framework, in which control of the donor–fullerene mutual orientation was achieved through chemical bond formation, in particular, by metal coordination. The 13C cross-polarization magic-angle spinning NMR spectroscopy, X-ray diffraction, and time-resolved fluorescence spectroscopy were performed for comprehensive structural analysis and energy-transfer (ET) studies of the fulleretic donor–acceptor scaffold. Furthermore, in combination with photoluminescence measurements, the theoretical calculations of the spectral overlap function, Förster radius, excitation energies, and band structure were employed to elucidate the photophysical and ET processes in the prepared fulleretic material. We envision that the well-defined fulleretic donor–acceptor …

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The Removal Kinetics Of Dissolved Organic Matter And The Optical Clarity Of Groundwater, Francis H. Chapelle, Yuan Shen, Eric W. Strom, Ronald Benner Apr 2016

The Removal Kinetics Of Dissolved Organic Matter And The Optical Clarity Of Groundwater, Francis H. Chapelle, Yuan Shen, Eric W. Strom, Ronald Benner

Faculty Publications

Concentrations of dissolved organic matter (DOM) and ultraviolet/visible light absorbance decrease systematically as groundwater moves through the unsaturated zones overlying aquifers and along flowpaths within aquifers. These changes occur over distances of tens of meters (m) implying rapid removal kinetics of the chromophoric DOM that imparts color to groundwater. A one-compartment input-output model was used to derive a differential equation describing the removal of DOM from the dissolved phase due to the combined effects of biodegradation and sorption. The general solution to the equation was parameterized using a 2-year record of dissolved organic carbon (DOC) concentration changes in groundwater at …

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Predicting Dissolved Lignin Phenol Concentrations In The Coastal Ocean From Chromophoric Dissolved Organic Matter (Cdom) Absorption Coefficients, Cédric G. Fichot, Ronald Benner, Karl Kaiser, Yuan Shen, Rainer M. W. Amon, Hiroshi Ogawa, Chua-Jung Lu Feb 2016

Predicting Dissolved Lignin Phenol Concentrations In The Coastal Ocean From Chromophoric Dissolved Organic Matter (Cdom) Absorption Coefficients, Cédric G. Fichot, Ronald Benner, Karl Kaiser, Yuan Shen, Rainer M. W. Amon, Hiroshi Ogawa, Chua-Jung Lu

Faculty Publications

Dissolved lignin is a well-established biomarker of terrigenous dissolved organic matter (DOM) in the ocean, and a chromophoric component of DOM. Although evidence suggests there is a strong linkage between lignin concentrations and chromophoric dissolved organic matter (CDOM) absorption coefficients in coastal waters, the characteristics of this linkage and the existence of a relationship that is applicable across coastal oceans remain unclear. Here, 421 paired measurements of dissolved lignin concentrations (sum of nine lignin phenols) and CDOM absorption coefficients [ag(λ)] were used to examine their relationship along the river-ocean continuum (0–37 salinity) and across contrasting coastal oceans (sub-tropical, temperate, high-latitude). …

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Binomial Regression With A Misclassified Covariate And Outcome., Sheng Luo, Wenyaw Chan, Michelle A Detry, Paul J Massman, R S. Doody Feb 2016

Binomial Regression With A Misclassified Covariate And Outcome., Sheng Luo, Wenyaw Chan, Michelle A Detry, Paul J Massman, R S. Doody

Faculty Publications

Misclassification occurring in either outcome variables or categorical covariates or both is a common issue in medical science. It leads to biased results and distorted disease-exposure relationships. Moreover, it is often of clinical interest to obtain the estimates of sensitivity and specificity of some diagnostic methods even when neither gold standard nor prior knowledge about the parameters exists. We present a novel Bayesian approach in binomial regression when both the outcome variable and one binary covariate are subject to misclassification. Extensive simulation results under various scenarios and a real clinical example are given to illustrate the proposed approach. This approach …

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Expansion Of The Manage Database With Forest And Drainage Studies, Daren R. Harmel, Laura E. Christianson, Matthew W. Mcbroom, Douglas R. Smith, Kori D. Higgs Jan 2016

Expansion Of The Manage Database With Forest And Drainage Studies, Daren R. Harmel, Laura E. Christianson, Matthew W. Mcbroom, Douglas R. Smith, Kori D. Higgs

Faculty Publications

The “Measured Annual Nutrient loads from AGricultural Environments” (MANAGE) database was published in 2006 to expand an early 1980s compilation of nutrient export (load) data from cultivated and pasture/range land at the field or farm scale. Then in 2008, MANAGE was updated with 15 additional studies, and nitrogen (N) and phosphorus (P) concentrations in runoff were added. Since then, MANAGE has undergone significant expansion adding N and P water quality along with relevant management and site characteristic data from: (1) 30 runoff studies from forested land uses, (2) 91 drainage water quality studies from drained land, and (3) 12 additional …

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Evaluating Interactive Transect Area Assessments Hands-On Instruction For Natural Resource Undergraduate Students, Daniel Unger, Sarah Schwab, Ryan Jacques, Yanli Zhang, I-Kuai Hung, David L. Kulhavy Jan 2016

Evaluating Interactive Transect Area Assessments Hands-On Instruction For Natural Resource Undergraduate Students, Daniel Unger, Sarah Schwab, Ryan Jacques, Yanli Zhang, I-Kuai Hung, David L. Kulhavy

Faculty Publications

Undergraduate students pursuing a Bachelor of Science in Spatial Science degree at Stephen F. Austin State University (SFASU) receive instruction in the spatial sciences with a focus on hands-on applications. All undergraduate students take the course Introduction to Spatial Science which includes a comprehensive overview of spatial science incorporating a comparison of standard inexpensive area assessment techniques with high-end computer based area assessment methodologies. Students within this course were instructed how to assess the area of a surface feature on an aerial image with a ruler applying the transect method. Student's average Root Mean Square Error (RMSE) between a student's …

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Spatial Distribution Of Earthworms In An East Texas Forest Ecosystem, Melissa A. Bozarth, Kenneth W. Farrish, George A. Damoff, James Van Kley, J. Leon Young Jan 2016

Spatial Distribution Of Earthworms In An East Texas Forest Ecosystem, Melissa A. Bozarth, Kenneth W. Farrish, George A. Damoff, James Van Kley, J. Leon Young

Faculty Publications

Earthworms were collected and identified in different ecological habitats of the Stephen F. Austin Experimental Forest (SFAEF) in the Piney Woods Ecoregion (PWE) of Texas. Earthworm spatial distribution data were collected over four distinct ecological habitats with a range of soil conditions and vegetative cover. A total of 128 sampling plots were surveyed in two different, broadly defined locations (mesic slope = 68 plots, dry-mesic upland = 60 plots). Using multivariate classification/ordination (TWINSPAN) and detrended correspondence analysis (DCA) of overstory vegetation data, these two locations were further divided into four distinct habitats: dry-mesic mixed upland, transitional zone, mesic slope and …

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Water Soluble Cationic Porphyrin Sensor For Detection Of Hg2+, Pb2+, Cd2+, And Cu2+, Matibur Zamadar, Christopher Orr, Miranda Uherek Jan 2016

Water Soluble Cationic Porphyrin Sensor For Detection Of Hg2+, Pb2+, Cd2+, And Cu2+, Matibur Zamadar, Christopher Orr, Miranda Uherek

Faculty Publications

Here we report the sensing properties of the aqueous solution of meso-tetra(N-methyl-4-pyridyl)porphine tetrachloride (1) for simultaneous detection of toxic metal ions by using UV-vis spectroscopy. Cationic porphyrin 1 displayed different electronic absorptions in UV-vis region upon interacting with Hg2+, Pb2+, Cd2+, and Cu2+ ions in neutral water solution at room temperature. Quite interestingly, the porphyrin 1 showed that it can function as a single optical chemical sensor and/or metal ion receptor capable of detecting two or more toxic metal ions, particularly Hg2+, Pb2+, and Cd2+ ions coexisting in a water sample. Porphyrin 1 in an aqueous solution provides a unique …

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