University of Tennesse

Metropolitan Government of Nashville-Davidson (balance), TN, United States

University of Tennesse

Metropolitan Government of Nashville-Davidson (balance), TN, United States
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Liu R.,Oak Ridge National Laboratory | Mahurin S.M.,Oak Ridge National Laboratory | Li C.,Oak Ridge National Laboratory | Li C.,Vanderbilt University | And 8 more authors.
Angewandte Chemie - International Edition | Year: 2011

C shells: A facile and versatile synthesis using dopamine as a carbon source gives hollow carbon spheres and yolk-shell Au@Carbon nanocomposites (see pictures). The uniform nature of dopamine coatings and their high carbon yield endow the products with high structural integrity. The Au@C nanocomposites are catalytically active. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Martha S.K.,Oak Ridge National Laboratory | Martha S.K.,Indian Institute of Technology Hyderabad | Nanda J.,Oak Ridge National Laboratory | Nanda J.,University of Tennesse | And 7 more authors.
RSC Advances | Year: 2014

We report novel electrode architectures for high capacity multivalent conversion compounds such as iron (ii and iii) fluoride. The material and electrode design approach addresses the intrinsically poor transport and diffusion kinetics associated with ionic solids such as iron fluorides and significantly improves their electrochemical and cycle life performance. A comparison is made between the performances of 3D electrode architecture versus the slurry coated fluoride electrodes. Detailed microstructural analysis and mechanistic scenarios are discussed that would enable development of practical high energy density conversion based electrodes for energy storage application. © 2014 The Royal Society of Chemistry.

Croce Jr. R.A.,University of Connecticut | Vaddiraju S.,Biorasis Inc. | Vaddiraju S.,University of Connecticut | Kondo J.,University of Connecticut | And 7 more authors.
Biomedical Microdevices | Year: 2013

Implantable sensors for continuous glucose monitoring hold great potential for optimal diabetes management. This is often undermined by a variety of issues associated with: (1) negative tissue response; (2) poor sensor performance; and (3) lack of device miniaturization needed to reduce implantation trauma. Herein, we report our initial results towards constructing an implantable device that simultaneously address all three aforementioned issues. In terms of device miniaturization, a highly miniaturized CMOS (complementary metal-oxide- semiconductor) potentiostat and signal processing unit was employed (with a combined area of 0.665 mm2). The signal processing unit converts the current generated by a transcutaneous, Clark-type amperometric sensor to output frequency in a linear fashion. The Clark-type amperometric sensor employs stratification of five functional layers to attain a well-balanced mass transfer which in turn yields a linear sensor response from 0 to 25 mM of glucose concentration, well beyond the physiologically observed (2 to 22 mM) range. In addition, it is coated with a thick polyvinyl alcohol (PVA) hydrogel with embedded poly(lactic-co-glycolic acid) (PLGA) microspheres intended to provide continuous, localized delivery of dexamethasone to suppress inflammation and fibrosis. In vivo evaluation in rat model has shown that the transcutaneous sensor system reproducibly tracks repeated glycemic events. Clarke's error grid analysis on the as - obtained glycemic data has indicated that all of the measured glucose readings fell in the desired Zones A & B and none fell in the erroneous Zones C, D and E. Such reproducible operation of the transcutaneous sensor system, together with low power (140 μW) consumption and capability for current-to-frequency conversion renders this a versatile platform for continuous glucose monitoring and other biomedical sensing devices. © 2012 Springer Science+Business Media, LLC.

Alderman D.H.,University of Tennesse | Inwood J.,University of Tennessee at Knoxville
Annals of the American Association of Geographers | Year: 2016

This article explores spatial mobility as a form of African American resistance and self-determination. We argue for examining the everyday activism and “countermobility work” of ordinary people of color as they move in ways that subvert, negotiate, and survive white supremacy. These ideas are developed through a historical case study not typically identified with the black civil rights struggle, specifically the National Association for Stock Car Auto Racing (NASCAR) and the “hard driving” of Wendell Scott. The first and only African American driver to win at NASCAR’s top level, Scott raced throughout the segregated South and faced considerable discrimination in what was otherwise an all-white sport. We offer a critical (re)reading of Scott’s racing career as antiracism mobility work and focus on the bodily, social, and technological practices he employed to maintain and even enhance his mobility around tracks and to and from races. Scott did not represent his efforts in terms of civil rights activism, but it is important to contextualize black resistance outside the confines of formal protest to include the struggle for survivability and material reproduction. The work of racing and driving was part of Scott’s geographically situated political practice and important to the struggle to access and move about the sport of stock car track racing and hence the larger U.S. landscape of citizenship. Our discussion has implications for analyzing historic practices of resistance but also has currency for understanding how countermobility practices remain central to resisting continuing racial discrimination. © 2016 by American Association of Geographers.

Nochetto R.H.,University of Maryland University College | Otarola E.,University of Maryland University College | Salgado A.J.,University of Maryland University College | Salgado A.J.,University of Tennesse
Foundations of Computational Mathematics | Year: 2015

The purpose of this work is to study solution techniques for problems involving fractional powers of symmetric coercive elliptic operators in a bounded domain with Dirichlet boundary conditions. These operators can be realized as the Dirichlet-to-Neumann map for a degenerate/singular elliptic problem posed on a semi-infinite cylinder, which we analyze in the framework of weighted Sobolev spaces. Motivated by the rapid decay of the solution to this problem, we propose a truncation that is suitable for numerical approximation. We discretize this truncation using first degree tensor product finite elements. We derive a priori error estimates in weighted Sobolev spaces. The estimates exhibit optimal regularity but suboptimal order for quasi-uniform meshes. For anisotropic meshes instead, they are quasi-optimal in both order and regularity. We present numerical experiments to illustrate the method’s performance. © 2014, SFoCM.

McFarlane N.,University of Tennesse
Midwest Symposium on Circuits and Systems | Year: 2012

In this work, we model single photon avalanche diodes (SPADs) as communication channels. We apply classical Shannon results for a Gaussian channel to typical SPAD circuits. Thus we look at the information rate and the bit energy of the circuit. By considering the noise sources for a generic SPAD sensor we develop the information rate model as a function of the excess bias voltage and perimeter gate voltage. We find that when considering only the dark count rate that there is a single optimum excess bias voltage that gives the maximum information rate. We conclude there is an excess voltage, gate voltage pair that optimizes the information rate. © 2012 IEEE.

Walter K.H.,Veterans Medical Research Foundation | Varkovitzky R.L.,Veterans Affairs Puget Sound Health Care System | Owens G.P.,University of Tennesse | Lewis J.,Trauma Recovery Center | Chard K.M.,Trauma Recovery Center
Journal of Consulting and Clinical Psychology | Year: 2014

Objective: Across the Veterans Affairs (VA) Healthcare System, outpatient and residential posttraumatic stress disorder (PTSD) treatment programs are available to veterans of all ages and both genders; however, no research to date has compared these treatment options. This study compared veterans who received outpatient (n = 514) to those who received residential treatment (n = 478) within a VA specialty clinic on demographic and pretreatment symptom variables. Further, the study examined pre- to posttreatment symptom trajectories across the treatment programs. Method: All 992 veterans met diagnostic criteria for PTSD and attended at least 1 session of cognitive processing therapy (CPT) in either the outpatient or residential program. Bivariate analyses were utilized to investigate differences between samples on demographic variables and severity of pretreatment symptoms. Multilevel modeling (MLM) was used to investigate the change in symptomatology between the 2 samples from pre- to posttreatment. Results: Analyses indicated that the samples differed on all demographic and pretreatment symptom variables, with residential patients reporting higher scores on all assessment measures. MLM results demonstrated that symptom scores improved for all veterans across time, with outpatients consistently reporting fewer symptoms at both time points. The time by program interaction was significant for PTSD-related symptom trajectories, but not for the depression-related symptom trajectory. Conclusion: This is the 1st study to compare pretreatment characteristics and treatment outcome between veterans receiving outpatient and residential PTSD treatment. Findings may help clinicians select appropriate care for their patients by identifying relevant pretreatment characteristics and generally informing expectations of treatment outcome. © 2014 APA.

Callen B.L.,University of Tennesse
Research in gerontological nursing | Year: 2011

The purpose of this study was to examine the relationships among stress, infectious illness, and religiousness/spirituality in community-dwelling older adults in the southeastern United States. Four assessment tools were completed by 82 older adults (mean age = 74, age range = 65 to 91): the Perceived Stress Scale, the Carr Infection Symptom Checklist (SCL), the Brief Multidimensional Measurement of Religiousness/Spirituality, and a demographic form. A significant correlation was found between stress and SCL scores; however, four dimensions of religiousness/spirituality moderated the relationship between stress and infection. Older adults who were unable to forgive themselves or forgive others, or feel forgiven by God, were more likely to have had an infection in the previous month. Increased infections also occurred when older participants did not feel they had religious support from their congregations. Using these findings, gerontological nurses are well positioned to deliver tailored stress management and forgiveness interventions when older adults report increased stress. Copyright 2011, SLACK Incorporated.

Zhan Z.,Northeast Forestry University | Li B.,Northeast Forestry University | Xu M.,Northeast Forestry University | Guo Z.,University of Tennesse
High Performance Polymers | Year: 2016

Nano-silica had been used as a synergistic agent for the preparation of aluminum diethylphosphinate (AlPi) flame retardant polyamide 66 (PA66/AlPi) and PA66/AlPi/nano-silica composites through twin-screw extrusion. The limiting oxygen index (LOI), used to characterize the minimum amount of oxygen needed to sustain a candle-like flame, revealed that the PA66/10%AlPi/1%nano-silica composites exhibited an excellent flame retardant efficiency with a high LOI value of 32.3%. The vertical flame test (UL-94) revealed that the PA66/10%AlPi/1%nano-silica composites passed the V-0 rating without drop melting. Cone calorimeter test revealed that the heat release rate and total heat rate for the PA66/10%AlPi/1%nano-silica composites were significantly decreased by 51.1 and 16.8%, respectively, compared with those of pure PA66. The thermogravimetric analysis showed that the PA66/10%AlPi/1%nano-silica composites had vast chars of 8.1% even at 800°C, indicating that nano-silica could promote the char formation of the PA66 composites. Scanning electron microscopy indicated a solid and tough residue of the burned PA66/10%AlPi/1%nano-silica composites as compared with the very loose and brickle residue of the burned pure PA66, indicating that a suitable amount of nano-silica played a synergistic effect in the flame retardancy. © 2015 The Author(s).

Kabalka G.W.,University of Tennesse | Yao M.-L.,University of Tennesse | Akula M.,University of Tennesse | Yong L.,University of Tennesse
Pure and Applied Chemistry | Year: 2012

Isotopes have played an important role in chemistry, biology, and medicine. For the last three decades, we have focused on the use of organoboron compounds as precursors to isotopically labeled physiologically active reagents. During that period, we have successfully developed methods for incorporating short- and long-lived isotopes of carbon, nitrogen, oxygen, and the halogens using a variety of reactive organoboron precursors. In addition, labeling strategies employing polymer-supported organoboron derivatives were developed. In this report, we present a short overview focused on the evolution of radiolabeling techniques based on boron chemistry. © 2012 IUPAC.

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