Digital Commons Network^™

Hydrogen Evolution Reaction Measurements Of Dealloyed Porous Nicu, Kyla Koboski, Evan Nelsen, Jennifer R. Hampton

Faculty Publications

Porous metals are of interest for their high surface area and potential for enhanced catalytic behavior. Electrodeposited NiCu thin films with a range of compositions were electrochemically dealloyed to selectively remove the Cu component. The film structure, composition, and reactivity of these samples were characterized both before and after the dealloying step using scanning electron microscopy, energy-dispersive spectroscopy, and electrochemical measurements. The catalytic behavior of the dealloyed porous Ni samples towards the hydrogen evolution reaction was measured and compared to that of the as-deposited samples. The dealloyed samples were generally more reactive than their as-deposited counterparts at low overpotentials, making …

Short, Strong Halogen Bonding In Co-Crystals Of Pyridyl Bis-Urea Macrocycles And Iodoperfluorocarbons, Michael F. Geer, James Mazzuca, Mark D. Smith, Linda S. Shimizu

Faculty Publications

No abstract provided.

Ground State Of The Singly Ionized Oxygen Vacancy In Rutile Tio2, A. T. Brant, Nancy C. Giles, Shan Yang (杨山), M. A. R. Sarker, S. Watauchi, M. Nagao, I. Tanaka, D. A. Tryk, A. Manivannan, Larry E. Halliburton

Faculty Publications

Results from electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) experiments are used to establish the model for the ground state of the singly ionized oxygen vacancy in the interior of bulk rutile TiO₂ crystals. Hyperfine from ⁴⁷Ti and ⁴⁹Ti nuclei show that the unpaired electron in this S = 1/2 defect is localized on one titanium ion adjacent to the oxygen vacancy (i.e., the spin is not shared by two titanium ions). These defects are formed at low temperature (∼35 K) in as-grown oxidized crystals when sub-band-gap 442 nm laser light converts doubly ionized nonparamagnetic …

Measurement Of Inelastic J/Ψ And Ψ′ Photoproduction At Hera, H. Abramowicz, I. Abt, L. Adamczyk, M. Adamus, R. Aggarwal, S. Antonelli, P. Antonioli, A. Antonov, M. Arneodo, O. Arslan, V. Aushev, Y. Aushev, O. Bachynska, A. Bamberger, A. N. Barakbaev, G. Barbagli, G. Bari, F. Barreiro, N. Bartosik, D. Bartsch, M. Basile, O. Behnke, J. Behr, U. Behrens, L. Bellagamba, A. Bertolin, S. Bhadra, M. Bindi, C. Blohm, V. Bokhonov, T. Bołd, Margarita C. K. Mattingly

Faculty Publications

The cross sections for inelastic photoproduction of J/ψ and ψ′ mesons have been measured in ep collisions with the ZEUS detector at HERA, using an integrated luminosity of 468 pb-1 collected in the period 1996-2007. The ψ′ to J/ψ cross section ratio was measured in the range 0.55 < z < 0.9 and 60 < W < 190 GeV as a function of W, z and pT. Here W denotes the photon-proton centre-of-mass energy, z is the fraction of the incident photon energy carried by the meson and p T is the transverse momentum of the meson with respect to the beam axis. The J/ψ cross sections were measured for 0.1 < z < 0.9, 60 < W < 240 GeV and pT > 1 GeV. Theoretical predictions within the non-relativistic QCD framework including NLO colour-singlet and colour-octet contributions were compared to the data, as were predictions based on the k T-factorisation approach. © 2013 SISSA.

Protein Structure Validation And Identification From Unassigned Residual Dipolar Coupling Data Using 2d-Pdpa, Arjang Fahim, Rishi Mukhopadhayay, Ryan Yandle, James H. Prestegard, Homayoun Valafar

Faculty Publications

More than 90% of protein structures submitted to the PDB each year are homologous to some previously characterized protein structure. The extensive resources that are required for structural characterization of proteins can be justified for the 10% of the novel structures, but not for the remaining 90%. This report presents the 2D-PDPA method, which utilizes unassigned residual dipolar coupling in order to address the economics of structure determination of routine proteins by reducing the data acquisition and processing time. 2D-PDPA has been demonstrated to successfully identify the correct structure of an array of proteins that range from 46 to 445 …

A Supramolecular Strategy To Assemble Multifunctional Viral Nanoparticles, Limin Chen, Xia Zhao, Yuan Lin, Yubin Huang, Qian Wang

Faculty Publications

Using a one-pot approach driven by the supramolecular interaction between β-cyclodextrin and adamantyl moieties, multifunctional viral nanoparticles can be facilely formulated for biomedical applications.

A Forward-Secure Certificate-Based Signature Scheme, Jiguo Li, Huiyun Teng, Xinyu Huang, Yichen Zhang, Jianying Zhou

Faculty Publications

Cryptographic computations are often carried out on insecure devices for which the threat of key exposure raises a serious concern. In an effort to address the key exposure problem, the notion of forward security was first presented by Günther in 1990. In a forward-secure scheme, secret keys are updated at regular periods of time; exposure of the secret key corresponding to a given time period does not enable an adversary to ‘break’ the scheme for any prior time period. In this paper, we first introduce forward security into certificate-based cryptography and define the security model of forward-secure certificate-based signatures (CBSs). …

Cross-Species Malaria Immunity Induced By Chemically Attenuated Parasites, Michael F. Good, Jennifer M. Reiman, I. Bibiana Rodriguez, Koichi Ito, Stephanie K. Yanow, Ibrahim M. El-Deeb, Michael R. Batzloff, Danielle I. Stanisic, Christian Engwerda, Terry Spithill, Stephen L. Hoffman, Moses Lee, Virginia Mcphun

Faculty Publications

Vaccine development for the blood stages of malaria has focused on the induction of antibodies to parasite surface antigens, most of which are highly polymorphic. An alternate strategy has evolved from observations that low-density infections can induce antibody-independent immunity to different strains. To test this strategy, we treated parasitized red blood cells from the rodent parasite Plasmodium chabaudi with secocyclopropyl pyrrolo indole analogs. These drugs irreversibly alkylate parasite DNA, blocking their ability to replicate. After administration in mice, DNA from the vaccine could be detected in the blood for over 110 days and a single vaccination induced profound immunity to …

Positive Equilibrium Solutions To General Population Model, Joon Hyuk Kang

Faculty Publications

In this paper, we investigate conditions for the existence of positive solution to the following general elliptic system with various growth conditions: {Δu + u(a + g(u, v)) = 0 Δv + v(d + h(u, v)) = 0 u|∂ω=v|∂ω=0 in ω. Our arguments mainly rely on super-sub solutions, maximum principles, spectrum estimates, and some detailed properties for the solution of logistic equations. © 2013 Academic Publications, Ltd.

Electron Transfer By Excited Benzoquinone Anions: Slow Rates For Two-Electron Transitions, Matibur Zamadar, Andrew R. Cook, Anna Lewandowska-Andralojc, Richard Holroyd, Yan Jiang, Jin Bikalis, John R. Miller

Faculty Publications

Electron transfer (ET) rate constants from the lowest excited state of the radical anion of benzoquinone, BQ−•*, were measured in THF solution. Rate constants for bimolecular electron transfer reactions typically reach the diffusion-controlled limit when the free-energy change, ΔG°, reaches −0.3 eV. The rate constants for ET from BQ−•* are one-to-two decades smaller at this energy and do not reach the diffusion-controlled limit until −ΔG° is 1.5−2.0 eV. The rates are so slow probably because a second electron must also undergo a transition to make use of the energy of the excited state. Similarly, ET, from solvated electrons to neutral …

Why A 15 Minute Biological Detection System?, Doug Lewis

Faculty Publications

The biological defense community needs to take a hard look at the requirements and assumptions we use to develop our biological sensors. Today the point sensors currently deployed or in development can offer at best “near real time” detection. This translates into approximately 10-20 minutes from the time an agent passes over the device until an alarm is issued. Why are we working to develop detection hardware which in reality contributes little to no advantage to an operational environment? Should the DOD resist fielding (in the near term) “near real time” detection systems, and instead field slower (but much more …

Spatial And Seasonal Variability Of Dissolved Organic Matter In The Cariaco Basin, Laura Lorenzoni, Gordon T. Taylor, Claudia R. Benitez-Nelson, Dennis A. Hansell, Enrique Montes, Robert Masserini, Kent Fanning, Ramón Varela, Yrene Astor, Laurencia Guzmán, Frank E. Muller-Karger

Faculty Publications

[1] Dissolved organic carbon (DOC), nitrogen (DON), and phosphorus (DOP) were measured monthly at the CARIACO Time Series station (10°30′N, 64°40′W) in the southeastern Caribbean Sea between 2005 and 2012. Marked seasonal variability in DOC concentrations was observed, with lower values (~66 µM) in the upper water column (<75 >m) during the upwelling season (December–April) due to the injection of cool, DOC‐impoverished Subtropical Underwater from the Caribbean Sea. During the rainy season (May–November) waters were stratified and upper layer DOC concentrations increased to ~71 µM. Interannual variability in surface (1 m) concentrations of DOC was also observed in response to …

Context-Driven Image Annotation Using Imagenet, George E. Noel, Gilbert L. Peterson

Faculty Publications

Image annotation research has demonstrated success on test data for focused domains. Unfortunately, extending these techniques to the broader topics found in real world data often results in poor performance. This paper proposes a novel approach that leverages WordNet and ImageNet capabilities to annotate images based on local text and image features. Signatures generated from ImageNet images based on WordNet synonymous sets are compared using Earth Mover's Distance against the query image and used to rank order surrounding words by relevancy. The results demonstrate effective image annotation, producing higher accuracy and improved specificity over the ALIPR image annotation system. Abstract …

Measuring A Circle: A Math Lesson For Grades 5-10, Robert C. Moore

Faculty Publications

This article is designed to promote teaching methods that engage students in active learning and result in deep conceptual understanding by offering a sample lesson to help students (grades 5-10, ages 10-15) answer questions about and gain a deeper understanding of how to measure the circumference and area of a circle.

Variation Of Instructor-Student Interactions In An Introductory Interactive Physics Course, Emily West, Cassandra Paul, David Webb, Wendell Potter

Faculty Publications

The physics instruction at UC Davis for life science majors takes place in a long-standing reformed large-enrollment physics course in which the discussion or laboratory instructors (primarily graduate student teaching assistants) implement the interactive-engagement (IE) elements of the course. Because so many different instructors participate in disseminating the IE course elements, we find it essential to the instructors’ professional development to observe and document the student-instructor interactions within the classroom. Out of this effort, we have developed a computerized real-time instructor observation tool (RIOT) to take data of student-instructor interactions. We use the RIOT to observe 29 different instructors for …

Geology Of The Western Llano Uplift, Fredericksburg To Mason, Texas, R. Larell Nielson, Chris Barker

Faculty Publications

This year's Texas Academy of Science Geology Field Trip will visit six interesting locations in the Texas Hill Country (Figure 01). At Bear Mountain quarry, former location of Balanced Rock, the contact between the Precambrian Bear Mountain Pluton and surrounding Cretaceous Edwards Group will be examined. Along Crab Apple Creek, south of Enchanted Rock, excellent exposures of the Hickory Sandstone provide the opportunity to study sedimentary structures and cross-bedding that represent the Sauk sequence deposited during the Cambrian Period (Figure 02). Next we will look at a Gypsum Mine and deposits of evaporites from the Cretaceous Kirschberg Lagoon (Figure 03 …

A Short Introduction To Numerical Linked-Cluster Expansions, Baoming Tang, Ehsan Khatami, Marcos Rigol

Faculty Publications

We provide a pedagogical introduction to numerical linked-cluster expansions (NLCEs). We sketch the algorithm for generic Hamiltonians that only connect nearest-neighbor sites in a finite cluster with open boundary conditions. We then compare results for a specific model, the Heisenberg model, in each order of the NLCE with the ones for the finite cluster calculated directly by means of full exact diagonalization. We discuss how to reduce the computational cost of the NLCE calculations by taking into account symmetries and topologies of the linked clusters. Finally, we generalize the algorithm to the thermodynamic limit, and discuss several numerical resummation techniques …

Nursing Student Voices: Reflections On An International Service Learning Experience, Molly Kerby, Eve Main

Faculty Publications

For the past decade participation in service and experiential learning in higher education has increased. The purpose of this study was to explore the lived experience of BSN and MSN students participating in a multidisciplinary service-learning course in a rural, underserved village in Belize. Researchers analyzed student journals utilizing qualitative data analysis techniques. There were eight consistent themes found in the student journals. The findings indicate that international service learning opportunities increase students' awareness of their place in a global society and the potential contribution they can make in society. For the past decade, service and experiential learning in higher …

Note: A Simple Thermal Gradient Annealing Unit For The Treatment Of Thin Films, C. J. Metting, Johnathan K. Bunn, Ellen A. Underwood, Yihao Zhu, G. Koley, T. Crawford, Jason R. Hattrick-Simpers

Faculty Publications

A gradient annealing cell has been developed for the high-throughput study of thermalannealing effects on thin-film libraries in different environments. The inexpensive gradientannealing unit permits temperature gradients as large as 28 °C/mm and can accommodate samples ranging in length from 13 mm to 51 mm. The system was validated by investigating the effects of annealing temperature on the crystallinity, resistivity, and transparency of tin-doped indium oxide deposited on a glass substrate by magnetron sputtering. The unit developed in this work will permit the rapid optimization of materials properties such as crystallinity, homogeneity, and conductivity across a variety of applications.

Optical Down-Conversion In Doped Znse:Tb3+ Nanocrystals, Sandip Das, K. C. Mandal

Faculty Publications

No abstract provided.

Insertion Of Lithium Ions Into Tio2 (Rutile) Crystals: An Electron Paramagnetic Resonance Study Of The Li-Associated Ti3+ Small Polaron, A. T. Brant, Nancy C. Giles, Larry E. Halliburton

Faculty Publications

Electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) are used to identify a Ti³⁺-Li⁺ complex in TiO₂ crystals having the rutile structure. This defect consists of an interstitial Li⁺ ion adjacent to a substitutional Ti³⁺ ion (the unpaired electron on the Ti³⁺ ion provides charge compensation for the Li⁺ ion). The neutral Ti³⁺-Li⁺ complex is best described as a donor-bound small polaron and is similar in structure to the recently reported neutral fluorine and hydrogen donors in TiO₂ (rutile). Lithium ions are diffused into the crystals at …

Toward Designed Singlet Fission: Solution Photophysics Of Two Indirectly Coupled Covalent Dimers Of 1,3-Diphenylisobenzofuran, Justin C. Johnson, Akin Akdag, Matibur Zamadar, Xudong Chen, Andrew F. Schwerin, Irina Paci, Millicent B. Smith, Zdenek Havlas, John R. Miller, Mark A. Ratner, Arthur J. Nozik, Josef Michl

Faculty Publications

In order to identify optimal conditions for singlet fission, we are examining the photophysics of 1,3- diphenylisobenzofuran (1) dimers covalently coupled in various ways. In the two dimers studied presently, the coupling is weak. The subunits are linked via the para position of one of the phenyl substituents, in one case (2) through a CH2 linker and in the other (3) directly, but with methyl substituents in ortho positions forcing a nearly perpendicular twist between the two joint phenyl rings. The measurements are accompanied with density functional theory (DFT) and timedependent DFT (TD-DFT) calculations. Although in neat solid state, 1 …

The Schrödinger Equation With Friction From The Quantum Trajectory Perspective, Sophya V. Garashchuk, Vaibhav Dixit, Bing Gu, James Mazzuca

Faculty Publications

Similarity of equations of motion for the classical and quantum trajectories is used to introduce afriction term dependent on the wavefunction phase into the time-dependent Schrödingerequation. The term describes irreversible energy loss by the quantum system. The force offriction is proportional to the velocity of a quantum trajectory. The resulting Schrödinger equationis nonlinear, conserves wavefunction normalization, and evolves an arbitrary wavefunction into the ground state of the system (of appropriate symmetry if applicable). Decrease in energy is proportional to the average kinetic energy of the quantum trajectory ensemble. Dynamics in the high friction regime is suitable for simple models of …

Experimental Determination Of Electron-Hole Pair Creation Energy In 4h-Sic Epitaxial Layer: An Absolute Calibration Approach, S. K. Chaudhuri, K. J. Zavalla, K. C. Mandal

Faculty Publications

No abstract provided.

Riemannian Submersions And Lagrangian Isometric Immerson 1, Yun Myung Oh

Faculty Publications

In [1], it has shown that if a Riemannian manifold admits a non- trivial Riemannian submersion with total geodesic fibers, then it cannot be isometrically immersed in any Riemannian manifold of non-positive sectional curvature as a minimal submanifold. In this paper, we consider a nontrivial Riemannian submersion and investigate some properties on Lagrangian iso- metric immersions using the submersion invariant.

The Global Sustainability Transition: It Is More Than Changing Light Bulbs, Michael P. Weinstein, R. Eugene Turner, Carles Ibanez

Faculty Publications

Current policies and norms to reconcile human demands for resources with the Earth’s ability to supply them have resulted in practices that mainly treat the symptoms of unsustainability rather than their underlying causes. Moreover, the increase in our knowledge about humankind’s role in ecosystems is not keeping pace with our understanding of the consequences of our actions, resulting in a deepening inability to address sustainability issues. The extreme complexity and intricate workings of the world require the expansion of our mental models in a systems-thinking framework if we are to realize a sustainable place for humans in it. The challenge …

Evaporite Karst And Hydrogeology Of The Castile Formation: Culberson County, Texas And Eddy County, New Mexico, Kevin W. Stafford

Faculty Publications

Karst development in Permian Castile evaporites has resulted in complex speleogenetic evolution with multiple phases of diagenetic overprinting. More than 10,000 surficial features, primarily sinkholes, occur throughout Culberson County, Texas, and Eddy County, New Mexico, based on GIS-analyses where laminated Castile sulfates crop out. Cave development is largely the result of hypogene processes, where ascending fluids from the underlying Bell Canyon Formation migrate near vertically through the Castile Formation, creating caves up to 100 meters deep and over 500 meters long, which have been breached through a combination of collapse and surface denudation. Numerous small and laterally limited epigene features …

Delineation And Classification Of Karst Depressions Using Lidar: Fort Hood Military Installation, Texas, Melinda G. Shaw-Faulkner, Kevin W. Stafford, Aaron W. Bryant

Faculty Publications

The Fort Hood Military Installation is a karst landscape characterized by Cretaceous-age limestone plateaus and canyons in Bell and Coryell Counties, Texas. The area is located in the Lampasas Cut Plain region of the Edwards Plateau and is stratigraphically defined by exposures of the Fredericksburg Group. Spatial interpolation of 105 km2 of the Fort Hood Military Installation provided depression data that were delineated and classified using geoanalytical methods. Most of the karst features within the study area are predominantly surficial expressions of collapse features, creating windows into karst conduits with surficial exposures of epikarst spatially limited.

The increasing capabilities of …

Clastic Sinkhole And Pseudokarst Development In East Texas, Kevin W. Stafford, Melinda G. Shaw-Faulkner, Wesley A. Brown

Faculty Publications

Pseudokarst development in East Texas is controlled primarily by a combination of suffosion and preferential flow paths, often creating small ephemeral sinkholes but occasionally persistent features develop in more indurated facies. Pseudokarst occurs in Claiborne (Eocene) strata in Angelina, Cherokee, Nacogdoches, Panola, Rusk, San Augustine and Shelby counties. Strata consist of interbedded fine- and coarse-grained clastics with variable cementation and associated permeabilities.

Probability Inequalities For The Sum Of Random Variables When Sampling Without Replacement, Jeremy Becnel, Kent Riggs, Dean Young

Faculty Publications

Exponential-type upper bounds are formulated for the probability that the maximum of the partial sample sums of discrete random variables having finite equispaced support exceeds or differs from the population mean by a specified positive constant. The new inequalities extend the work of Serfling (1974). An example of the results are given to demonstrate their efficacy.