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Articles 2581 - 2610 of 3168

Full-Text Articles in Physical Sciences and Mathematics

Ill-Posedness Of The Two-Dimensional Keller-Segel Model In Triebel-Lizorkin Spaces, Chao Deng, John Villavert Jan 2014

Ill-Posedness Of The Two-Dimensional Keller-Segel Model In Triebel-Lizorkin Spaces, Chao Deng, John Villavert

School of Mathematical & Statistical Sciences Faculty Publications

This article proves the ill-posedness of the Cauchy problem for the two-dimensional Keller–Segel model in Triebel–Lizorkin spaces, for . In particular, it is shown that solutions can develop norm inflation under certain settings in that the solution can become arbitrarily large after an arbitrarily short time even for small initial data.

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Constraints On Cosmic Strings From The Ligo-Virgo Gravitational-Wave Detectors, Daniel Bessis, Teviet Creighton, H. Daveloza, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Robert Stone, Lappoon R. Tang, Cristina V. Torres Jan 2014

Constraints On Cosmic Strings From The Ligo-Virgo Gravitational-Wave Detectors, Daniel Bessis, Teviet Creighton, H. Daveloza, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Robert Stone, Lappoon R. Tang, Cristina V. Torres

Physics & Astronomy Faculty Publications

Cosmic strings can give rise to a large variety of interesting astrophysical phenomena. Among them, powerful bursts of gravitational waves (GWs) produced by cusps are a promising observational signature. In this Letter we present a search for GWs from cosmic string cusps in data collected by the LIGO and Virgo gravitational wave detectors between 2005 and 2010, with over 625 days of live time. We find no evidence of GW signals from cosmic strings. From this result, we derive new constraints on cosmic string parameters, which complement and improve existing limits from previous searches for a stochastic background of GWs …

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Bright Microwave Pulses From Psr B0531+21 Observed With A Prototype Transient Survey Receiver, J. A. O'Dea, F. A. Jenet, Tsan Huei Cheng, Chau M. Buu, Martin Beroiz, Sami W. Asmar, J. W. Armstrong Jan 2014

Bright Microwave Pulses From Psr B0531+21 Observed With A Prototype Transient Survey Receiver, J. A. O'Dea, F. A. Jenet, Tsan Huei Cheng, Chau M. Buu, Martin Beroiz, Sami W. Asmar, J. W. Armstrong

Physics & Astronomy Faculty Publications

Recent discoveries of transient radio events have renewed interest in time-variable astrophysical phenomena. Many radio transient events are rare, requiring long observing times for reliable statistical study. The National Aeronautics and Space Administration/Jet Propulsion Laboratory's Deep Space Network (DSN) tracks spacecraft nearly continuously with 13 large-aperture, low system temperature radio antennas. During normal spacecraft operations, the DSN processes only a small fraction of the pre-detection bandwidth available from these antennas; any information in the remaining bandwidth, e.g., from an astronomical source in the same antenna beam as the spacecraft, is currently ignored. As a firmware modification to the standard DSN …

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Application Of A Hough Search For Continuous Gravitational Waves On Data From The Fifth Ligo Science Run, J. Aasi, J. Abadie, B. P. Abbott, Teviet Creighton, H. Daveloza, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Robert Stone, A. S. Stroeer, Lappoon R. Tang, Cristina V. Torres Jan 2014

Application Of A Hough Search For Continuous Gravitational Waves On Data From The Fifth Ligo Science Run, J. Aasi, J. Abadie, B. P. Abbott, Teviet Creighton, H. Daveloza, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Robert Stone, A. S. Stroeer, Lappoon R. Tang, Cristina V. Torres

Physics & Astronomy Faculty Publications

We report on an all-sky search for periodic gravitational waves in the frequency range 50–1000 Hz with the first derivative of frequency in the range −8.9 × 10−10 Hz s−1 to zero in two years of data collected during LIGO's fifth science run. Our results employ a Hough transform technique, introducing a χ2 test and analysis of coincidences between the signal levels in years 1 and 2 of observations that offers a significant improvement in the product of strain sensitivity with compute cycles per data sample compared to previously published searches. Since our search yields no surviving candidates, we present …

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Treatment Of Calibration Uncertainty In Multi-Baseline Cross-Correlation Searches For Gravitational Waves, J. T. Whelan, E. L. Robinson, Joseph D. Romano, E. H. Thrane Jan 2014

Treatment Of Calibration Uncertainty In Multi-Baseline Cross-Correlation Searches For Gravitational Waves, J. T. Whelan, E. L. Robinson, Joseph D. Romano, E. H. Thrane

Physics & Astronomy Faculty Publications

Uncertainty in the calibration of gravitational wave (GW) detector data leads to systematic errors, which must be accounted for in setting limits on the strength of GW signals. When cross-correlation measurements are made using data from a pair of instruments, as in searches for a stochastic GW background, the calibration uncertainties of the individual instruments can be combined into an uncertainty associated with the pair. With the advent of multi-baseline GW observation (e.g., networks consisting of multiple detectors such as the LIGO observatories and Virgo), a more sophisticated treatment is called for. We have described how the correlations between calibration …

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Parallel Phase Modulation Scheme For Interferometric Gravitational-Wave Detectors, M. T. Hartman, V. Quetschke, D. B. Tanner, D. H. Reitze, G. Mueller Jan 2014

Parallel Phase Modulation Scheme For Interferometric Gravitational-Wave Detectors, M. T. Hartman, V. Quetschke, D. B. Tanner, D. H. Reitze, G. Mueller

Physics & Astronomy Faculty Publications

Advanced LIGO (aLIGO) requires multiple frequency sidebands to disentangle all of the main interferometer's length signals. This paper presents the results of a risk reduction experiment to produce two sets of frequency sidebands in parallel, avoiding mixed 'sidebands on sidebands'. Two phase modulation frequencies are applied to separate Electro-Optic Modulators (EOMs), with one EOM in each of the two arms of a Mach-Zehnder interferometer. In this system the Mach-Zehnder's arm lengths are stabilized to reduce relative intensity noise in the recombined carrier beam by feeding a corrective control signal back to the Rubidium Titanyl Phosphate (RTP) EOM crystals to drive …

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Pt-Symmetric Acoustics, Xuefeng Zhu, Hamidreza Ramezani, Chengzhi Shi, Jie Zhu, Xiang Zhang Jan 2014

Pt-Symmetric Acoustics, Xuefeng Zhu, Hamidreza Ramezani, Chengzhi Shi, Jie Zhu, Xiang Zhang

Physics & Astronomy Faculty Publications

We introduce here the concept of acoustic parity-time (PT) symmetry and demonstrate the extraordinary scattering characteristics of the acoustic PT medium. On the basis of exact calculations, we show how an acoustic PT -symmetric medium can become unidirectionally transparent at given frequencies. Combining such a PT -symmetric medium with transformation acoustics, we design two-dimensional symmetric acoustic cloaks that are unidirectionally invisible in a prescribed direction. Our results open new possibilities for designing functional acoustic devices with directional responses.

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Search For Gravitational Radiation From Intermediate Mass Black Hole Binaries In Data From The Second Ligo-Virgo Joint Science Run, J. Aasi, B. P. Abbott, H. Daveloza, S. R. Morriss, Soma Mukherjee, M. E. Normandin, O. Puncken, Volker Quetschke, Malik Rakhmanov, K. E. Ramirez, Robert Stone, Cristina V. Torres, G. Valdes Jan 2014

Search For Gravitational Radiation From Intermediate Mass Black Hole Binaries In Data From The Second Ligo-Virgo Joint Science Run, J. Aasi, B. P. Abbott, H. Daveloza, S. R. Morriss, Soma Mukherjee, M. E. Normandin, O. Puncken, Volker Quetschke, Malik Rakhmanov, K. E. Ramirez, Robert Stone, Cristina V. Torres, G. Valdes

Physics & Astronomy Faculty Publications

This paper reports on an unmodeled, all-sky search for gravitational waves from merging intermediate mass black hole binaries (IMBHB). The search was performed on data from the second joint science run of the LIGO and Virgo detectors (July 2009–October 2010) and was sensitive to IMBHBs with a range up to ∼200 Mpc, averaged over the possible sky positions and inclinations of the binaries with respect to the line of sight. No significant candidate was found. Upper limits on the coalescence-rate density of nonspinning IMBHBs with total masses between 100 and 450 M⊙ and mass ratios between 0.25 and 1 were …

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A Program For Optical Observations Of Advanced Ligo Early Triggers In The Southern Hemisphere, Matthew Benacquista, Chris Belczynski, Martin Beroiz, Maria Branchesi, Carlos Colazo, Mario C. Diaz, Mancheno Dominguez, Diego Garcia Lambas, Shengnan Liang, Lucas M. Macri, Tania Peñuela Jan 2014

A Program For Optical Observations Of Advanced Ligo Early Triggers In The Southern Hemisphere, Matthew Benacquista, Chris Belczynski, Martin Beroiz, Maria Branchesi, Carlos Colazo, Mario C. Diaz, Mancheno Dominguez, Diego Garcia Lambas, Shengnan Liang, Lucas M. Macri, Tania Peñuela

Physics & Astronomy Faculty Publications

In this poster we present a plan to follow-up optically early triggers from the Advanced LIGO gravitational wave detectors, which will start operating in scientific mode in the northern summer of 2015.

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Gravity Effect On Electrical Field Generation And Charge Carriers Transfer During Combustion Synthesis Of Sulfides, A. A. Markov, I. A. Filimonov, Karen S. Martirosyan Jan 2014

Gravity Effect On Electrical Field Generation And Charge Carriers Transfer During Combustion Synthesis Of Sulfides, A. A. Markov, I. A. Filimonov, Karen S. Martirosyan

Physics & Astronomy Faculty Publications

The effect of gravity on the electric potential generated by the combustion synthesis of zinc sulfide is analyzed using the numerical simulation. Recent experimental studies on generation of electric voltage during combustion synthesis of zinc sulfide (ZnS) have revealed high voltage signals (4 V) with duration about 1 s, which are much higher than those produced by the gas–solid and solid–solid combustion reactions studied previously. These data have raised the question about mechanism of such a phenomenon. In our previous work we developed a novel (distributed) model describing the electric potential generation during combustion synthesis of sulfides (CSS) that didn't …

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Fabrication Of Yttrium Ferrite Nanoparticles By Solution Combustion Synthesis, A. A. Saukhimov, Mkhitar A. Hobosyan, Gamage C. Dannangoda, N. N. Zhumabekova, S. E. Kumekov Jan 2014

Fabrication Of Yttrium Ferrite Nanoparticles By Solution Combustion Synthesis, A. A. Saukhimov, Mkhitar A. Hobosyan, Gamage C. Dannangoda, N. N. Zhumabekova, S. E. Kumekov

Physics & Astronomy Faculty Publications

The ternary oxide system Y-Fe-O presents fascinating magnetic properties that are sensitive to the crystalline size of particles. There is a major challenge to fabricate these materials in nano-crystalline forms due to particle conglomeration during nucleation and synthesis. In this paper we report the fabrication of nano sized crystalline yttrium ferrite by solution combustion synthesis (SCS) where yttrium and iron nitrates were used as metal precursors with glycine as a fuel. The magnetic properties of the product can be selectively controlled by adjusting the ratio of glycine to metal nitrates. Yttrium ferrite nano-powder was obtained by using three concentration of …

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Free-Energy Calculations For Semi-Flexible Macromolecules: Applications To Dna Knotting And Looping, Stefan M. Giovan, Robert G. Scharein, Andreas Hanke, Stephen D. Levene Jan 2014

Free-Energy Calculations For Semi-Flexible Macromolecules: Applications To Dna Knotting And Looping, Stefan M. Giovan, Robert G. Scharein, Andreas Hanke, Stephen D. Levene

Physics & Astronomy Faculty Publications

We present a method to obtain numerically accurate values of configurational free energies of semiflexible macromolecular systems, based on the technique of thermodynamic integration combined with normal-mode analysis of a reference system subject to harmonic constraints. Compared with previous free-energy calculations that depend on a reference state, our approach introduces two innovations, namely, the use of internal coordinates to constrain the reference states and the ability to freely select these reference states. As a consequence, it is possible to explore systems that undergo substantially larger fluctuations than those considered in previous calculations, including semiflexible biopolymers having arbitrary ratios of contour …

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Implementation Of An F-Statistic All-Sky Search For Continuous Gravitational Waves In Virgo Vsr1 Data, J. Aasi, B. P. Abbott, R. Abbott, T. Abbott, M. R. Abernathy, Mario C. Diaz, Malik Rakhmanov, Joseph D. Romano, Soma Mukherjee, Volker Quetschke, Teviet Creighton, Robert Stone Jan 2014

Implementation Of An F-Statistic All-Sky Search For Continuous Gravitational Waves In Virgo Vsr1 Data, J. Aasi, B. P. Abbott, R. Abbott, T. Abbott, M. R. Abernathy, Mario C. Diaz, Malik Rakhmanov, Joseph D. Romano, Soma Mukherjee, Volker Quetschke, Teviet Creighton, Robert Stone

Physics & Astronomy Faculty Publications

We present an implementation of the -statistic to carry out the first search in data from the Virgo laser interferometric gravitational wave detector for periodic gravitational waves from a priori unknown, isolated rotating neutron stars. We searched a frequency f0 range from 100 Hz to 1 kHz and the frequency dependent spindown f1 range from Hz s−1 to zero. A large part of this frequency–spindown space was unexplored by any of the all-sky searches published so far. Our method consisted of a coherent search over two-day periods using the -statistic, followed by a search for coincidences among the …

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Biosensors And Nanobiosensors: Design And Applications, Ahmed Touhami Jan 2014

Biosensors And Nanobiosensors: Design And Applications, Ahmed Touhami

Physics & Astronomy Faculty Publications

The goal of this chapter is to cover the full scope of biosensors. It offers a survey of the principles, design, operation, and biomedical applications of the most popular types of biosensing devices in use today. By discussing recent research and future trends based on many excellent books and reviews, it is hoped to give the readers a comprehensive view on this fast growing field.

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Lessons Learned In Establishing Stem Student Cohorts At A Border University And The Effect On Student Retention And Success, Mikhail M. Bouniaev, Immanuel Edinbarough, Bill W. Elliott Jan 2014

Lessons Learned In Establishing Stem Student Cohorts At A Border University And The Effect On Student Retention And Success, Mikhail M. Bouniaev, Immanuel Edinbarough, Bill W. Elliott

School of Mathematical & Statistical Sciences Faculty Publications

The University of Texas at Brownsville (UTB) serves more than 8,000 students in the Lower Rio Grande Valley area and broader Mexico region. UTB is a Hispanic-serving institution that attracts students from the surrounding areas, including the Mexico border region. The College of Science, Mathematics and Technology (CSMT) established a Science, Technology, Engineering, and Mathematics (STEM) cohort program to help the majority of students to earn a degree in a STEM field in the shortest possible time. The challenges and obstacles encountered during the planning and implementation phase of the STEM cohort program are discussed in this paper, as are …

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Unidirectional Lasing Emerging From Frozen Light In Nonreciprocal Cavities, Hamidreza Ramezani, S. Kalish, I. Vitebskiy, T. Kottos Jan 2014

Unidirectional Lasing Emerging From Frozen Light In Nonreciprocal Cavities, Hamidreza Ramezani, S. Kalish, I. Vitebskiy, T. Kottos

Physics & Astronomy Faculty Publications

We introduce a class of unidirectional lasing modes associated with the frozen mode regime of nonreciprocal slow-wave structures. Such asymmetric modes can only exist in cavities with broken timereversal and space inversion symmetries. Their lasing frequency coincides with a spectral stationary inflection point of the underlying passive structure and is virtually independent of its size. These unidirectional lasers can be indispensable components of photonic integrated circuitry.

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Synthesis Of Novel C-4 Disubstituted Β-Lactams Through Staudinger Cycloaddition Reaction, Robert Rodriguez, Anjali Nambiar, Ram N. Yadav, Bimal K. Banik Jan 2014

Synthesis Of Novel C-4 Disubstituted Β-Lactams Through Staudinger Cycloaddition Reaction, Robert Rodriguez, Anjali Nambiar, Ram N. Yadav, Bimal K. Banik

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

Synthesis of novel C-4 disubstituted beta-lactam that has N-methyl pyrrole system has been achieved through Staudinger cycloaddition reaction of acid chloride and imine. Interestingly, this reaction has produced a single stereoisomer.

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Adapting In-Game Agent Behavior By Observation Of Players Using Learning Behavior Trees, Emmett Tomai, Roberto Flores Jan 2014

Adapting In-Game Agent Behavior By Observation Of Players Using Learning Behavior Trees, Emmett Tomai, Roberto Flores

Computer Science Faculty Publications

In this paper we describe Learning Behavior Trees, an extension of the popular game AI scripting technique. Behavior Trees provide an effective way for expert designers to describe complex, in-game agent behaviors. Scripted AI captures human intuition about the structure of behavioral decisions, but suffers from brittleness and lack of the natural variation seen in human players. Learning Behavior Trees are designed by a human designer, but then are trained by observation of players performing the same role, to introduce human-like variation to the decision structure. We show that, using this model, a single hand-designed Behavior Tree can cover a …

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Overview Of The Large-Scale Biosphere-Atmosphere Experiment In Amazonia Data Model Intercomparison Project (Lba-Dmip), Luis Gustavo Gonçalves De Gonçalves, Jordan S. Borak, Marcos Heil Costa, Scott R. Saleska, Ian Baker, Natalia Restrepo-Coupe, Michel Nobre Muza, Benjamin Poulter, Hans Verbeeck, Bradley O. Christoffersen Dec 2013

Overview Of The Large-Scale Biosphere-Atmosphere Experiment In Amazonia Data Model Intercomparison Project (Lba-Dmip), Luis Gustavo Gonçalves De Gonçalves, Jordan S. Borak, Marcos Heil Costa, Scott R. Saleska, Ian Baker, Natalia Restrepo-Coupe, Michel Nobre Muza, Benjamin Poulter, Hans Verbeeck, Bradley O. Christoffersen

School of Integrative Biological & Chemical Sciences Faculty Publications

A fundamental question connecting terrestrial ecology and global climate change is the sensitivity of key terrestrial biomes to climatic variability and change. The Amazon region is such a key biome: it contains unparalleled biological diversity, a globally significant store of organic carbon, and it is a potent engine driving global cycles of water and energy. The importance of understanding how land surface dynamics of the Amazon region respond to climatic variability and change is widely appreciated, but despite significant recent advances, large gaps in our understanding remain. Understanding of energy and carbon exchange between terrestrial ecosystems and the atmosphere can …

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What Drives The Seasonality Of Photosynthesis Across The Amazon Basin? A Cross-Site Analysis Of Eddy Flux Tower Measurements From The Brasil Flux Network, Natalia Restrepo-Coupe, Humberto R. Da Rocha, Lucy R. Hutyra, Alessandro C. Da Araujo, Laura S. Borma, Bradley O. Christoffersen, Osvaldo M.R. Cabral, Plinio B. De Camargo, Fernando L. Cardoso, Antonio C.Lola Da Costa Dec 2013

What Drives The Seasonality Of Photosynthesis Across The Amazon Basin? A Cross-Site Analysis Of Eddy Flux Tower Measurements From The Brasil Flux Network, Natalia Restrepo-Coupe, Humberto R. Da Rocha, Lucy R. Hutyra, Alessandro C. Da Araujo, Laura S. Borma, Bradley O. Christoffersen, Osvaldo M.R. Cabral, Plinio B. De Camargo, Fernando L. Cardoso, Antonio C.Lola Da Costa

School of Integrative Biological & Chemical Sciences Faculty Publications

We investigated the seasonal patterns of Amazonian forest photosynthetic activity, and the effects thereon of variations in climate and land-use, by integrating data from a network of ground-based eddy flux towers in Brazil established as part of the 'Large-Scale Biosphere Atmosphere Experiment in Amazonia' project. We found that degree of water limitation, as indicated by the seasonality of the ratio of sensible to latent heat flux (Bowen ratio) predicts seasonal patterns of photosynthesis. In equatorial Amazonian forests (5° N-5° S), water limitation is absent, and photosynthetic fluxes (or gross ecosystem productivity, GEP) exhibit high or increasing levels of photosynthetic activity …

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Sensitivity Curves For Searches For Gravitational-Wave Backgrounds, E. H. Thrane, Joseph D. Romano Dec 2013

Sensitivity Curves For Searches For Gravitational-Wave Backgrounds, E. H. Thrane, Joseph D. Romano

Physics & Astronomy Faculty Publications

We propose a graphical representation of detector sensitivity curves for stochastic gravitational-wave backgrounds that takes into account the increase in sensitivity that comes from integrating over frequency in addition to integrating over time. This method is valid for backgrounds that have a power-law spectrum in the analysis band. We call these graphs “power-law integrated curves.” For simplicity, we consider cross-correlation searches for unpolarized and isotropic stochastic backgrounds using two or more detectors. We apply our method to construct power-law integrated sensitivity curves for second-generation ground-based detectors such as Advanced LIGO, space-based detectors such as LISA and the Big Bang Observer, …

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Peakon, Pseudo-Peakon, And Cuspon Solutions For Two Generalized Camassa- Holm Equations, Jibin Li, Zhijun Qiao Dec 2013

Peakon, Pseudo-Peakon, And Cuspon Solutions For Two Generalized Camassa- Holm Equations, Jibin Li, Zhijun Qiao

School of Mathematical & Statistical Sciences Faculty Publications

In this paper, we study peakon, cuspon, and pseudo-peakon solutions for two generalized Camassa-Holm equations. Based on the method of dynamical systems, the two generalized Camassa-Holm equations are shown to have the parametric representations of the solitary wave solutions such as peakon, cuspon, pseudo-peakons, and periodic cusp solutions. In particular, the pseudo-peakon solution is for the first time proposed in our paper. Moreover, when a traveling system has a singular straight line and a heteroclinic loop, under some parameter conditions, there must be peaked solitary wave solutions appearing.

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The Computation Of Fluid Velocity In A Closed Cavity With A Moving Lid, Daniel A. Montez Dec 2013

The Computation Of Fluid Velocity In A Closed Cavity With A Moving Lid, Daniel A. Montez

Theses and Dissertations - UTB/UTPA

We consider a cavity filled with fluid whose three sides are stationary and the lid at the top is moving at a constant speed. The flow in the cavity is modeled using the conservation of mass and momentum equations with proper boundary conditions. We compute the fluid velocity for the steady state case using the finite element method. We seek the weak formulation and develop a finite element model based on the Galerkin method. Furthermore we use the penalty function method to modify our weak formulation to eliminate the pressure. The Gaussian quadrature method is used to evaluate our integrals …

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Reduction Of Nitroaromatic Compounds With Sodium Borohydride Using Transition Metal Sulfides, Samuel Pina Jr. Dec 2013

Reduction Of Nitroaromatic Compounds With Sodium Borohydride Using Transition Metal Sulfides, Samuel Pina Jr.

Theses and Dissertations - UTB/UTPA

The following systems: NaBH4/Fe3S4, NaBH4/Co3S4, NaBH4/NiS, NaBH4/CuS, and NaBH4/ZnS, were investigated for their nitro reducing abilities. Quantitative conversions were observed for the reduction of nitrobenzene with NaBH4/Co3S4 and NaBH4/NiS systems as opposed to only 9% conversion without any catalyst, representing a ten-fold increase in the reducing ability of NaBH4. In ethanol, various nitroaromatic compounds were also successfully reduced in moderate to high yields with 3 molar equivalents of NaBH4, demonstrating a mild alternative for the effective reduction of nitroaromatic compounds to their corresponding aryl amines. Screening of catalysts was carried out using gas chromatography. All products were characterized using 1 …

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Oxidation Of Dibenzothiophene To Dibenzothiophene Sulfone Using Tio2, Juan H. Leal Dec 2013

Oxidation Of Dibenzothiophene To Dibenzothiophene Sulfone Using Tio2, Juan H. Leal

Theses and Dissertations - UTB/UTPA

The oxidation of dibenzothiophene (DBT) to dibenzothiophene-sulfone has been considered as an alternate method to remove sulfur from crude oil. This study demonstrates that the oxidative desulfurization (ODS) of DBT to DBT-sulfone occurs using rutile TiO2 as a catalyst with the aid of O2. In addition, anatase and brookite were synthesized and tested in the reaction. Particle size of the catalysts was calculated and morphology was explored using SEM. A kinetic study was performed to determine the catalytic effect and activation energy of TiO2. The oxidation reaction was carried out by refluxing TiO2 and DBT in decahydronapthalene while flowing O2 …

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Remediation Of Copper(Ii) And Lead(Ii) From Aqueous Solution Using Engineered Iron Oxide And Manganese Oxide Nanomaterials, Carlos Tamez Jr. Dec 2013

Remediation Of Copper(Ii) And Lead(Ii) From Aqueous Solution Using Engineered Iron Oxide And Manganese Oxide Nanomaterials, Carlos Tamez Jr.

Theses and Dissertations - UTB/UTPA

Nano-sized Fe3O4, Fe2O3, Mn3O4, and MnO2 were synthesized by titration/precipitation and characterized using powder XRD. pH assays determined that optimum binding occurred at pH 4 for Fe3O4 and Fe2O3 and pH 3 for Mn3O4 and MnO2. Maximum adsorption of Cu(II) and Pb(II) occurred within 20 min or less of contact with the nanomaterials. The synthesized nanomaterials showed a binding preference for Pb(II) over Cu(II) at concentrations above 50 ppm. Batch studies also showed no significant reduction in the binding of copper and lead to either Fe3O4, Fe2O3, Mn3O4, or MnO2 in the presence of Na+ , K+ , Mg2+ or …

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Biological Compatibility And Cytotoxicity Studies Of Hepa-1c1c7, Hepg2, And Mcf-7 Cancer Cell Lines Upon Exposure To Silver, Palladium, And Gold Nanoparticles, M. Esther Salinas Dec 2013

Biological Compatibility And Cytotoxicity Studies Of Hepa-1c1c7, Hepg2, And Mcf-7 Cancer Cell Lines Upon Exposure To Silver, Palladium, And Gold Nanoparticles, M. Esther Salinas

Theses and Dissertations - UTB/UTPA

The field of nanomedicine has recently explored potential applications for cancer treatment ranging from drug delivery methods to cancer imaging techniques. Due to potential risks of nanomaterials affecting non-cancerous cells in the body, in vitro toxicity studies are being conducted. The nanoparticles (NPs) were synthesized from potassium tetrachloroaurate (III) hydrate, potassium tetrabromoaurate (III) dihydrate, potassium tetrachloropalladate (II), and silver nitrate. NPs were synthesized using the Turkevich method or through the sodium borohydride reduction. Particles synthesized using sodium borohydride were stabilized with cetyltrimethylammonium bromide (CTAB). The NPs under investigation were used to treat three cancer cell lines. The treated cells were …

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Oxidation Of Dibenzothiophene To Dibenzothiophene Sulfone Using Tungsten (Vi) Oxide, Alejandrina Rivera Dec 2013

Oxidation Of Dibenzothiophene To Dibenzothiophene Sulfone Using Tungsten (Vi) Oxide, Alejandrina Rivera

Theses and Dissertations - UTB/UTPA

The oxidation of dibenzothiophene (DBT) to dibenzothiophene-sulfone has been considered as an alternate method to remove sulfur from crude oil. This study demonstrates that the oxidative desulfurization (ODS) of DBT to DBT-sulfone occurs using WO3 as a catalyst. WO3 was synthesized and characterized using X-ray diffraction to determine the phase of WO3. Each reaction was refluxed and run for four hours using WO3 as a catalyst, dibenzothiphene, and four different solvents: decahydronapthalene, n-dodecane, decalin, and dodecane. The reactions were performed at temperatures ranging from 120 oC to 150 oC. Aliquots were taken at 30 minutes for up to four hours …

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A Survey Of Heavy Metals In Water, Soil And The Surrounding Plants In The Lower Rio Grande Valley, Erving W. Morelius Dec 2013

A Survey Of Heavy Metals In Water, Soil And The Surrounding Plants In The Lower Rio Grande Valley, Erving W. Morelius

Theses and Dissertations - UTB/UTPA

Heavy metal pollution of the environment in recent years has become a major issue of importance for both human and environmental health. Samples were investigated for the potential pollution of the area as it is a vital produce producing area. During the study plant, soil and water samples were collected from the Donna Reservoir and Canal System to test the concentration of various heavy metals. The heavy metals tested included both potentially toxic and micronutrients in the samples which included arsenic, cadmium, chromium, copper, iron, lead, nickel and sulfur. During the study, a sixty day sampling period was used to …

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The Relational Algebra Toolkit: A User-Friendly Approach To Presenting And Processing Relational Algebra Queries On The Web, Jeremy J. Miller Dec 2013

The Relational Algebra Toolkit: A User-Friendly Approach To Presenting And Processing Relational Algebra Queries On The Web, Jeremy J. Miller

Theses and Dissertations - UTB/UTPA

Relational algebra is the mathematical basis of tools to express and optimize queries on relational data. However, there exists no convenient way to directly use, express, store, render, visualize, and execute relational algebra over the Web. Educators and practitioners are limited to creating relational algebra expressions using TeX or equation editors which cannot execute them. This work presents a solution to this issue: the Relational Algebra Toolkit (RAT). Relational data and queries are represented using purpose-built XML vocabularies, to be both machine-processable and serializable. Encoded relational algebra expressions can be rendered as parenthetical expressions and as syntax trees, translated to …

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