Physical Sciences and Mathematics Commons^™

Analytic Derivative Couplings Between Configuration-Interaction-Singles States With Built-In Electron-Translation Factors For Translational Invariance, Shervin Fatehi, Ethan Alguire, Yihan Shao, Joseph Subotnik

Chemistry Faculty Publications and Presentations

We present a method for analytically calculating the derivative couplings between a pair of configuration-interaction-singles (CIS) excited states obtained in an atom-centered basis. Our theory is exact and has been derived using two completely independent approaches: one inspired by the Hellmann-Feynman theorem and the other following from direct differentiation. (The former is new, while the latter is in the spirit of existing approaches in the literature.) Our expression for the derivative couplings incorporates all Pulay effects associated with the use of an atom-centered basis, and the computational cost is minimal, roughly comparable to that of a single CIS energy gradient. …

User Choice Between Traditional And Computerized Methods: An Activity Perspective, Jun Sun

Information Systems Faculty Publications and Presentations

Numerous computerized methods emerge to replace traditional methods in people’s personal, work and social lives, but many are hesitant to make the transition. This study examines the factors that influence human choice between different methods. According to Activity Theory, traditional and computerized methods are both tools that a person uses for a certain task. The situated experiences with various methods shape people’s attitude toward using them later in terms of tool readiness. The understanding leads to hypothesized relationships between user-, method- and task-specific factors and the dependent variable. The results from an empirical study support that method experiences have strong …

Fabrication Of Mineralized Collagen From Bovine Waste Materials By Hydrothermal Method As Promised Biomaterials, Faheem A. Sheikh, M. A. Kanjwal, Javier Macossay-Torres, Muneeb A. Muhammad, Travis Cantu, Ioannis S. Chronakis, N. A. M. Barakat, Hak Yong Kim

Chemistry Faculty Publications and Presentations

In the present study, we aimed to produce mineralized-collagen by hydrothermal process. A simple method not depending on additional foreign chemicals has been employed to isolate the mineralized-collagen fibers from bovine waste. The process of extraction involves the use of hydrothermal method from available bovine bones. The structural and morphological properties of the collagen fibers were characterized by using scanning electron microscopy and transmission electron microscopy. These results indicated well received collagen fibers, having a diameter less than 1 μm and with established mineral content in the individual fibers. The X-ray diffraction showed the crystalline feature of the obtained nano-compounds. …

A Gravitational Wave Observatory Operating Beyond The Quantum Shot-Noise Limit: Squeezed Light In Application, J. Abadie, B. P. Abbott, T. D. Abbott, M. R. Abernathy, Matthew Benacquista, Teviet Creighton, H. Daveloza, Maria E. Diaz, R. Grosso, Soumya Mohanty, Soma Mukherjee, Volker Quetschke, Joseph D. Romano, Robert Stone, A. S. Stroeer

Physics and Astronomy Faculty Publications and Presentations

Around the globe several observatories are seeking the first direct detection of gravitational waves (GWs). These waves are predicted by Einstein's general theory of relativity(1) and are generated, for example, by black-hole binary systems(2). Present GW detectors are Michelson-type kilometre-scale laser interferometers measuring the distance changes between mirrors suspended in vacuum. The sensitivity of these detectors at frequencies above several hundred hertz is limited by the vacuum (zero-point) fluctuations of the electromagnetic field. A quantum technology-the injection of squeezed light(3)-offers a solution to this problem. Here we demonstrate the squeezed-light enhancement of GEO 600, which will be the GW observatory …

A Comprehensive Method For Fractionating Soil Organic Matter Not Protected And Protected From Decomposition By Physical And Chemical Mechanisms, César Plaza, José M. Fernández, Engil Isadora Pujol Pereira, Alfredo Polo

School of Earth, Environmental, and Marine Sciences Faculty Publications and Presentations

The objective of this work was to describe a method for isolating meaningful and measurable soil organic matter (SOM) pools that differ in the mechanisms by which they are protected from decomposition. The proposed method is appropriate for soil C stabilization and sequestration studies. Unlike previous fractionation schemes, this procedure allows free SOM located between aggregates (unprotected C pool) and SOM occluded within both macroaggregates and microaggregates (C weakly and strongly protected by physical mechanisms, respectively) to be recovered separately, freed from the soil mineral matrix and the mineral-associated SOM pool (C pool protected by chemical mechanisms) and thus well …

Infrared And Upconversion Spectroscopic Studies Of High Er3+Content Transparent Yag Ceramic, M. Pokhrel, G. A. Kumar, P. Samuel, K. I. Ueda, T. Yanagitani, H. Yagi, D. K. Sardar

Physics and Astronomy Faculty Publications and Presentations

In this article, we report the detailed spectroscopic studies of high Er3+content (50%) transparent YAG ceramic co-doped with nominal Cr3+ content (0.1 mol %). Various radiative and non-radiative spectroscopic properties such as radiative decay time, fluorescence branching ratio, emission/absorption cross sections, internal radiative quantum yields of the infrared and the upconverted emission bands are explored using standard experimental and theoretical methods and compared with YAG single crystal. Results show that although the non-radiative losses are high for 50% Er doped ceramic; several radiative spectral properties are almost in agreement with those for the single crystal YAG. Furthermore, because of the …

The Properties Of The Stellar Nuclei With The Host Galaxy Morphology In The Acsvcs, Hyun-Chul Lee

Physics and Astronomy Faculty Publications and Presentations

We have revisited the ACS Virgo Cluster Survey (ACSVCS), a Hubble Space Telescope program to obtain ACS/WFC g and z bands imaging for a sample of 100 early-type galaxies in the Virgo Cluster. In this study, we examine 51 nucleated early-type galaxies in the ACSVCS in order to look into the relationship between the photometric and structural properties of stellar nuclei and their host galaxies. We morphologically dissect galaxies into five classes. We note that (1) the stellar nuclei of dwarf early-type galaxies (dS0, dE, and dE,N) are generally fainter and bluer with g > 18.95 and (g-z) < 1.40 compared to some brighter and redder counterparts of the ellipticals (E) and lenticular galaxies (S0), (2) the g-band half-light radii of stellar nuclei of all dwarf early-type galaxies (dS0, dE, and dE,N) are smaller than 20 pc and their average is about 4 pc, and (3) the colors of red stellar nuclei with (g - z) > 1.40 in bright …

Tidal Perturbations To The Gravitational Inspiral Of J0651+2844, Matthew J. Benacquista, Kelly Holley-Bockelmann

Physics and Astronomy Faculty Publications and Presentations

The recently discovered J0651+2844 is a detached, eclipsing white dwarf binary with an orbital period of 765 s. We investigate the prospects for the detection of gravitational radiation from this system and estimate the effect of the tidal deformation of the low-mass component on the period evolution of the system. Because of the high inclination of the system, the amplitude of the gravitational waves at Earth will be as much as a factor of two lower than that from an optimally oriented system. The dominant contribution of tidal corrections to the period evolution comes from the increase in rotational energy …

Polycyclic Aromatic Compounds As Anticancer Agents: Evaluation Of Synthesis And In Vitro Cytotoxicity, Debasish Bandyopadhyay, Jose C. Granados, John D. Short, Bimal K. Banik

Chemistry Faculty Publications and Presentations

Polycyclic aromatic hydrocarbons (PAHs) are considered to be significant environmental carcinogens. Additionally, various planar ring systems are capable of intercalating with DNA, leading to a number of drugs that possess chemotherapeutic activity. In this study, three new polyaromatic compounds with a side chain were synthesized, and spectroscopic as well as elemental analyses were performed. The addition of the long chains to either chrysene or pyrene caused a red-shift in the spectral emission when compared to the corresponding polycyclic aromatic hydrocarbons itself. Furthermore, the cytotoxicity of the three novel polyaromatic compounds was evaluated in vitro in a panel of cultured mammalian …

A Truly Green Synthesis Of A-Aminonitriles Via Strecker Reaction, Debasish Bandyopadhyay, Juliana M. Velazquez, Bimal K. Banik

Chemistry Faculty Publications and Presentations

Background: The classical Strecker reaction is one of the simplest and most economical methods for the synthesis of racemic a-aminonitriles (precursor of a-amino acids) and pharmacologically useful compounds.

Results: Indium powder in water is shown to act as a very efficient catalyst for one-pot, three-component synthesis of a-aminonitriles from diverse amines, aldehydes and TMSCN. This general rapid method is applicable to a wide range of amines and aldehydes and produces products in excellent yield.

Conclusions: The present one-pot, three-component environmentally benign procedure for the synthesis of aaminonitriles will find application in the synthesis of complex biologically active molecules.

Sparse Spectral-Tau Method For The Three-Dimensional Helically Reduced Wave Equation On Two-Center Domains, Stephen R. Lau, Richard H. Price

Physics and Astronomy Faculty Publications and Presentations

We describe a multidomain spectral-tau method for solving the three-dimensional helically reduced wave equation on the type of two-center domain that arises when modeling compact binary objects in astrophysical applications. A global two-center domain may arise as the union of Cartesian blocks, cylindrical shells, and inner and outer spherical shells. For each such subdomain, our key objective is to realize certain (differential and multiplication) physical-space operators as matrices acting on the corresponding set of modal coefficients. We then achieve sparse realizations through the integration “preconditioning” of Coutsias, Hagstrom, Hesthaven, and Torres. Since ours is the first three-dimensional multidomain implementation of …

Bismuth Nitrate Pentahydrate-Induced Novel Nitration Of Eugenol, Luis Canales, Debasish Bandyopadhyay, Bimal K. Banik

Chemistry Faculty Publications and Presentations

Background: Eugenol, the main constituent of clove oil possesses a number of medicinal activities. To enhance the medicinal property, structural modification is required. On the other hand, bismuth nitrate pentahydrate has been established as an excellent eco-friendly nitrating agent for several classes of organic compounds.

Results: Bismuth nitrate pentahydrate-induced nitration of eugenol has been investigated very thoroughly. Twenty five different conditions have been studied. The microwave-induced solvent-free reaction has been identified as the best condition.

Conclusions: Spectral analyses confirm that 5-nitroeugenol is the sole product in all the cases. No oxidized or isomerized product could be detected.

Ferromagnetic Resonance On Ni Nanowire Arrays, Mircea Chipara, Ralph Skomski, Roger D. Kirby, David J. Sellmyer

Physics and Astronomy Faculty Publications and Presentations

Ferromagnetic resonance investigations on Ni nanowires are reported. The angular dependence of the resonance line position is analyzed within a thermodynamic approach that includes shape anisotropy (ellipsoids of revolution), magnetocrystalline anisotropies (cubic and uniaxial), and dipole–dipole interactions. The results are supported by hysteresis loops, obtained on the same sample.

Compact Binaries In Star Clusters - Ii. Escapers And Detection Rates, J. M.B. Downing, M. J. Benacquista, M. Giersz, R. Spurzem

Physics and Astronomy Faculty Publications and Presentations

We use a self-consistent Monte Carlo treatment of stellar dynamics to investigate black hole binaries that are dynamically ejected from globular clusters in order to determine if they will be gravitational wave sources. We find that many of the ejected binaries initially have short periods and will merge within a Hubble time due to gravitational wave radiation. Thus they are potential sources for ground-based gravitational wave detectors. We estimate the yearly detection rate for current and advanced ground-based detectors and find an enhancement over the rate predicted for binaries produced by pure stellar evolution in galactic fields. We conclude that, …

Beating The Spin-Down Limit On Gravitational Wave Emission From The Vela Pulsar, J. Abadie, B. P. Abbott, R. Abbott, M. Abernathy, T. Accadia, F. Acernese, C. Adams, R. Adhikari, C. Affeldt, B. Allen, G. S. Allen, E. Amador Ceron, D. Amariutei, R. S. Amin, S. B. Anderson, W. G. Anderson, F. Antonucci, K. Arai, M. A. Arain, M. C. Araya, S. M. Aston, P. Astone, D. Atkinson, P. Aufmuth, C. Aulbert, B. E. Aylott, S. Babak, P. Baker, G. Ballardin, S. Ballmer

Physics and Astronomy Faculty Publications and Presentations

We present direct upper limits on continuous gravitational wave emission from the Vela pulsar using data from the Virgo detector's second science run. These upper limits have been obtained using three independent methods that assume the gravitational wave emission follows the radio timing. Two of the methods produce frequentist upper limits for an assumed known orientation of the star's spin axis and value of the wave polarization angle of, respectively, 1.9 × 10-24 and 2.2 × 10-24, with 95% confidence. The third method, under the same hypothesis, produces a Bayesian upper limit of 2.1 × 10-24, with 95% degree of …

Structural Basis For Sequence Specific Dna Binding And Protein Dimerization Of Hoxa13, Yonghong Zhang, Christine A. Larsen, H. Scott Stadler, James B. Ames

Chemistry Faculty Publications and Presentations

The homeobox gene (HOXA13) codes for a transcription factor protein that binds to AT-rich DNA sequences and controls expression of genes during embryonic morphogenesis. Here we present the NMR structure of HOXA13 homeodomain (A13DBD) bound to an 11-mer DNA duplex. A13DBD forms a dimer that binds to DNA with a dissociation constant of 7.5 nM. The A13DBD/DNA complex has a molar mass of 35 kDa consistent with two molecules of DNA bound at both ends of the A13DBD dimer. A13DBD contains an N-terminal arm (residues 324 - 329) that binds in the DNA minor groove, and a C-terminal helix (residues …

Investigating Students' Mental Models And Knowledge Construction Of Microscopic Friction. I. Implications For Curriculum Design And Development, Edgar D. Corpuz, N. Sanjay Rebello

Physics and Astronomy Faculty Publications and Presentations

In this paper, we discuss the first phase of a multiphase study aimed at investigating the dynamics of students' knowledge construction in the context of unfamiliar physical phenomenon-microscopic friction. The first phase of this study involved the investigation of the variations in students' mental models of microscopic friction. Clinical interviews were conducted with 11 students enrolled in conceptual modern physics to elicit their ideas and generate themes of explanations. A phenomenographic approach of data analysis was employed to establish the variations in students' explanations. Results show that students' mental models of friction at the atomic level are dominated by their …

Near-Field Radiative Heat Transfer Between Macroscopic Planar Surfaces, R. S. Ottens, Volker Quetschke, Stacy Wise, A. A. Alemi, R. Lundock, G. Mueller, D. H. Reitze, D. B. Tanner, B. F. Whiting

Physics and Astronomy Faculty Publications and Presentations

Near-field radiation allows heat to propagate across a small vacuum gap at rates several orders of magnitude above that of far-field, blackbody radiation. Although heat transfer via near-field effects has been discussed for many years, experimental verification of this theory has been very limited. We have measured the heat transfer between two macroscopic sapphire plates, finding an increase in agreement with expectations from theory. These experiments, conducted near 300K, have measured the heat transfer as a function of separation over mm to μm and as a function of temperature differences between 2.5 and 30K. The experiments demonstrate that evanescence can …

Search For Gravitational Wave Bursts From Six Magnetars, J. Abadie, B. P. Abbott, R. Abbott, M. Abernathy, T. Accadia, F. Acernese, C. Adams, R. Adhikari, C. Affeldt, B. Allen, G. S. Allen, E. Amador Ceron, D. Amariutei, R. S. Amin, S. B. Anderson, W. G. Anderson, F. Antonucci, K. Arai, M. A. Arain, M. C. Araya, S. M. Aston, P. Astone, D. Atkinson, P. Aufmuth, C. Aulbert, B. E. Aylott, S. Babak, P. Baker, G. Ballardin, S. Ballmer

Physics and Astronomy Faculty Publications and Presentations

Soft gamma repeaters (SGRs) and anomalous X-ray pulsars (AXPs) are thought to be magnetars: neutron stars powered by extreme magnetic fields. These rare objects are characterized by repeated and sometimes spectacular gamma-ray bursts. The burst mechanism might involve crustal fractures and excitation of non-radial modes which would emit gravitational waves (GWs). We present the results of a search for GW bursts from six galactic magnetars that is sensitive to neutron star f-modes, thought to be the most efficient GW emitting oscillatory modes in compact stars. One of them, SGR 0501+4516, is likely 1kpc from Earth, an order of magnitude closer …

Search For Gravitational Waves From Binary Black Hole Inspiral Merger And Ringdown, J. Abadie, B. P. Abbott, R. Abbott, M. Abernathy, T. Accadia, F. Acernese, C. Adams, R. Adhikari, P. Ajith, B. Allen, G. S. Allen, E. Amador Ceron, R. S. Amin, S. B. Anderson, W. G. Anderson, F. Antonucci, M. A. Arain, M. C. Araya, M. Aronsson, Y. Aso, S. M. Aston, P. Astone, D. Atkinson, P. Aufmuth, C. Aulbert, S. Babak, P. Baker, G. Ballardin, T. Ballinger, S. Ballmer

Physics and Astronomy Faculty Publications and Presentations

We present the first modeled search for gravitational waves using the complete binary black-hole gravitational waveform from inspiral through the merger and ringdown for binaries with negligible component spin. We searched approximately 2 years of LIGO data, taken between November 2005 and September 2007, for systems with component masses of 1-99Mȯ and total masses of 25-100Mȯ. We did not detect any plausible gravitational-wave signals but we do place upper limits on the merger rate of binary black holes as a function of the component masses in this range. We constrain the rate of mergers for 19Mȯ≤m1, m 2≤28Mȯ binary black-hole …

A New Integrable Two-Component System With Cubic Nonlinearity, Junfeng Song, Changzheng Qu, Zhijun Qiao

School of Mathematical and Statistical Sciences Faculty Publications and Presentations

In this paper, a new integrable two-component system, mt=[m(uxvx−uv+uvx−uxv)]x,nt=[n(uxvx−uv+uvx−uxv)]x, where m=u−uxx and n=v−vxx, is proposed. Our system is a generalized version of the integrable system mt=[m(u2x−u2)]x, which was shown having cusped solution (cuspon) and W/M-shape soliton solutions by Qiao [J. Math. Phys. 47, 112701 (2006). The new system is proven integrable not only in the sense of Lax-pair but also in the sense of geometry, namely, it describes pseudospherical surfaces. Accordingly, infinitely many conservation laws are derived through recursion relations. Furthermore, exact solutions such as cuspons and W/M-shape solitons are also obtained.

On Detection Of The Stochastic Gravitational-Wave Background Using The Parkes Pulsar Timing Array, D. R.B. Yardley, W. A. Coles, G. B. Hobbs, J. P.W. Verbiest, R. N. Manchester, W. Van Straten, F. A. Jenet, M. Bailes, N. D.R. Bhat, S. Burke-Spolaor, D. J. Champion, A. W. Hotan, S. Oslowski, J. E. Reynolds, J. M. Sarkissian

Physics and Astronomy Faculty Publications and Presentations

We search for the signature of an isotropic stochastic gravitational-wave background in pulsar timing observations using a frequency-domain correlation technique. These observations, which span roughly 12yr, were obtained with the 64-m Parkes radio telescope augmented by public domain observations from the Arecibo Observatory. A wide range of signal processing issues unique to pulsar timing and not previously presented in the literature are discussed. These include the effects of quadratic removal, irregular sampling and variable errors which exacerbate the spectral leakage inherent in estimating the steep red spectrum of the gravitational-wave background. These observations are found to be consistent with the …

Systematics Of Black Hole Binary Inspiral Kicks And The Slowness Approximation, Richard H. Price, Gaurav Khanna, Scott A. Hughes

Physics and Astronomy Faculty Publications and Presentations

During the inspiral and merger of black holes, the interaction of gravitational wave multipoles carries linear momentum away, thereby providing an astrophysically important recoil, or “kick” to the system and to the final black hole remnant. It has been found that linear momentum during the last stage (quasinormal ringing) of the collapse tends to provide an “antikick” that in some cases cancels almost all the kick from the earlier (quasicircular inspiral) emission. We show here that this cancellation is not due to peculiarities of gravitational waves, black holes, or interacting multipoles, but simply to the fact that the rotating flux …

Ab Initio Description Of Nonlinear Dynamics Of Coupled Microdisk Resonators With Application To Self-Trapping Dynamics, Hamidreza Ramezani, Tsampikos Kottos, V. Shuvayev, L. Deych

Physics and Astronomy Faculty Publications and Presentations

An ab initio approach is used to describe the time evolution of the amplitudes of whispering gallery modes in a system of coupled microdisk resonators with Kerr nonlinearity. It is shown that this system demonstrates a transition between Josephson-like nonlinear oscillations and self-trapping behavior. Manifestation of this transition in the dynamics of radiative losses is studied.

Extensive Reproductive Disruption, Ovarian Masculinization And Aromatase Suppression In Atlantic Croaker In The Northern Gulf Of Mexico Hypoxic Zone, Peter Thomas, Md. Saydur Rahman

School of Earth, Environmental, and Marine Sciences Faculty Publications and Presentations

The long-term impacts on marine ecosystems of the recent dramatic worldwide increase in the incidence of coastal hypoxia are unknown. Here, we show widespread reproductive disruption in Atlantic croakers collected from hypoxic sites approximately 120 km apart in the extensive northern Gulf of Mexico continental shelf hypoxic zone. Gonadal growth and gamete production were impaired in croakers from hypoxic sites compared with fish from reference normoxic sites east of the Mississippi River Delta. Male germ cells were detected in approximately 19 per cent of croaker ovaries collected in the hypoxic region, but were absent in ovaries from normoxic sites. In …

Asimafoetidnol: A New Sesquiterpenoid Coumarin From The Gum Resin Of Ferula Assa-Foetida, Debasish Bandyopadhyay, Manas Banerjee, Subrata Laskar, Bidyut Basak

Chemistry Faculty Publications and Presentations

Chemical investigation of the gum resin of Ferula assa-foetida L. resulted in the isolation of a new sesquiterpenoid coumarin, 7-(((E)-5-((1S,3S,6S)-3,6- dihydroxy-2,2,6-trimethylcyclohexyl)-3-methylpent-2-en-1-yl)oxy) -2H-chromen-2-one (asimafoetidnol), together with several other known compounds. The structure of asimafoetidnol was established on the basis of spectroscopic analyses. Geometry optimization of the compound has been carried out using a DFT/B3LYP/3-21G* method.

Arecibo Palfa Survey And Einstein@Home: Binary Pulsar Discovery By Volunteer Computing, B. Knispel, P. Lazarus, B. Allen, D. Anderson, C. Aulbert, N. D.R. Bhat, O. Bock, S. Bogdanov, A. Brazier, F. Camilo, S. Chatterjee, J. M. Cordes, F. Crawford, J. S. Deneva, G. Desvignes, H. Fehrmann, P. C.C. Freire, D. Hammer, J. W.T. Hessels, F. A. Jenet, V. M. Kaspi, M. Kramer, J. Van Leeuwen, D. R. Lorimer, A. G. Lyne, B. Machenschalk, M. A. Mclaughlin, C. Messenger, D. J. Nice, M. A. Papa

Physics and Astronomy Faculty Publications and Presentations

We report the discovery of the 20.7ms binary pulsar J1952+2630, made using the distributed computing project Einstein@Home in Pulsar ALFA survey observations with the Arecibo telescope. Follow-up observations with the Arecibo telescope confirm the binary nature of the system. We obtain a circular orbital solution with an orbital period of 9.4hr, a projected orbital radius of 2.8lt-s, and a mass function of f = 0.15 M ⊙ by analysis of spin period measurements. No evidence of orbital eccentricity is apparent; we set a 2σ upper limit e ≲ 1.7 × 10 -3 . The orbital parameters suggest a massive white …

When Is Hyponormality For 2-Variable Weighted Shifts Invariant Under Powers?, Raul E. Curto, Jasang Yoon

School of Mathematical and Statistical Sciences Faculty Publications and Presentations

Abstract. For 2-variable weighted shifts W(α,β) ≡ (T1, T2) we study the invariance of (joint) khyponormality under the action (h, ℓ) 7→ W (h,ℓ) (α,β) := (T h 1 , T ℓ 2 ) (h, ℓ ≥ 1). We show that for every k ≥ 1 there exists W(α,β) such that W (h,ℓ) (α,β) is k-hyponormal (all h ≥ 2, ℓ ≥ 1) but W(α,β) is not k-hyponormal. On the positive side, for a class of 2-variable weighted shifts with tensor core we find a computable necessary condition for invariance. Next, we exhibit a large nontrivial class for which hyponormality …

Pulsar Timing Sensitivity To Very-Low-Frequency Gravitational Waves, Fredrick A. Jenet, J. W. Armstrong, Massimo Tinto

Physics and Astronomy Faculty Publications and Presentations

We compute the sensitivity, constrained by instrumental, propagation, and other fundamental noises, of pulsar timing to very-low-frequency gravitational waves (GWs). Reaching predicted GW signal strengths will require suppression of time-of-arrival fluctuations caused by interstellar plasma turbulence and a reduction of white rms timing noise to 100ns. Assuming negligible intrinsic pulsar rotational noise, perfect time transfer from time standard to observatory, and stable pulse profiles, the resulting single-pulsar signal-to-noise ratio=1 sensitivity is limited by terrestrial time standards at hrms∼2×10-16[f/(1cycle/year)]-1/2 for f<3×10-8Hz, where f is the Fourier frequency and a bandwidth of 1 cycle/(10 years) is assumed. Since this sensitivity is comparable to predicted GW signal levels, a reliable detection will require substantial signal-to-noise ratio improvement via pulsar timing array. © 2011 American Physical Society.

Fabrication Of Poly(Vinylidene Fluoride) (Pvdf) Nanofibers Containing Nickel Nanoparticles As Future Energy Server Materials, Faheem A. Sheikh, Travis Cantu, Javier Macossay-Torres, Hern Kim

Chemistry Faculty Publications and Presentations

In the present study, we introduce Poly(vinylidene fluoride) (PVDF) nanofibers containing nickel (Ni) nanoparticles (NPs) as a result of an electrospinning. Typically, a colloidal solution consisting of PVDF/Ni NPs was prepared to produce nanofibers embedded with solid NPs by electrospinning process. The resultant nanostructures were studied by SEM analyses, which confirmed well oriented nanofibers and good dispersion of Ni NPs over them. The XRD results demonstrated well crystalline feature of PVDF and Ni in the obtained nanostructures. Physiochemical aspects of prepared nano-structures were characterized for TEM which confirmed nanofibers were welloriented and had good dispersion of Ni NPs. Furthermore, the …