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Polymer-Cement Composites with Self-Healing Ability for Geothermal and Fossil Energy Applications
Childers, M. Ian,Nguyen, Manh-Thuong,Rod, Kenton A.,Koech, Phillip K.,Um, Wooyong,Chun, Jaehun,Glezakou, Vassiliki-Alexandra,Linn, Diana,Roosendaal, Timothy J.,Wietsma, Thomas W.,Huerta, Nicolas John American Chemical Society 2017 Chemistry of materials Vol.29 No.11
<P>Sealing of wellbores in geothermal and tight oil/gas reservoirs by filling the annulus with cement is a well-established practice. Failure of the cement as a result of physical and/or chemical stress is a common problem with serious environmental and financial consequences. Numerous alternative cement blends have been proposed for the oil and gas industry. Most of these possess poor mechanical properties, or are not designed to work in high temperature environments. This work reports on a novel polymer-cement composite with remarkable self-healing ability that maintains the required properties of typical wellbore cements and may be stable at most geothermal temperatures. We combine for the first time experimental analysis of physical and chemical properties with density functional theory simulations to evaluate cement performance. The thermal stability and mechanical strength are attributed to the formation of a number of chemical interactions between the polymer and cement matrix including covalent bonds, hydrogen bonding, and van der Waals interactions. Self-healing was demonstrated by sealing fractures with 0.3–0.5 mm apertures, 2 orders of magnitude larger than typical wellbore fractures. This polymer-cement composite represents a major advance in wellbore cementing that could improve the environmental safety and economics of enhanced geothermal energy and tight oil/gas production.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cmatex/2017/cmatex.2017.29.issue-11/acs.chemmater.7b00344/production/images/medium/cm-2017-00344c_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cm7b00344'>ACS Electronic Supporting Info</A></P>
A Search for Exoplanets in Short-Period Binary Star Systems
Kaitchuck, Ronald,Turner, Garrison,Childers, Joseph The Korean Space Science Society 2012 Journal of Astronomy and Space Sciences Vol.29 No.1
This paper reports the progress of a search for exoplanets with S-type orbits in short-period binary star systems. The selected targets have stellar orbital periods of just a few days. These systems are eclipsing binaries so that exoplanet transits, if planets exist, will be highly likely. We report the results for seven binary star systems.
A Search for Exoplanets in Short-Period Binary Star Systems
Ronald Kaitchuck,Garrison Turner,Joseph Childers 한국우주과학회 2012 Journal of Astronomy and Space Sciences Vol.29 No.1
This paper reports the progress of a search for exoplanets with S-type orbits in short-period binary star systems. The se\-lected targets have stellar orbital periods of just a few days. These systems are eclipsing binaries so that exoplanet transits, if planets exist, will be highly likely. We report the results for seven binary star systems.
A Single-Dose Resveratrol Treatment in a Mouse Model of Amyotrophic Lateral Sclerosis
Chad D. Marker,김은국,David J. Gifondorwa,Martin K. Childers,Carol E. Milligan 한국식품영양과학회 2010 Journal of medicinal food Vol.13 No.5
The underlying causes of denervation of the neuromuscular junction and eventual motor neuron death in amyotrophic lateral sclerosis (ALS) have not been resolved. The superoxide dismutase 1 (SOD1)G93A mutant mouse is a frequently used animal model of ALS. We hypothesized that resveratrol (RSV), a polyphenolic molecule that enhances mammalian NAD+-dependent SIRT1 deacetylases and may increase life span, would improve motor function and survival in the SOD1 mouse model via modulation of p53 acetylation. Data were collected for mean survival times, neuromuscular performance on the ROTOR-ROD™ (San Diego Instruments, San Diego, CA, USA), body weight, and p53 acetylation. Mean survival times were not statistically different (P=.23) between control and experimental (RSV-fed) groups (mean±SD, control [n=11] 138±6 days vs. experimental [n=10] 135±8 days). Performance was not significantly different between groups at time points corresponding to 50%, 80%, and 90% mean life span (P=.46), nor did RSV treatment attenuate body weight loss. Thus although manipulation of SIRT1 deacetylase activity has effects at the protein level in healthy aging organisms, we conclude that RSV treatment does not lead to functional improvement or increased longevity in a mouse model of ALS. We speculate that RSV-mediated modulation of p53 acetylation is either incapable of increasing or insufficient to increase motor performance and longevity in this model of ALS.
2006 WHOLE EARTH TELESCOPE OBSERVATIONS OF GD358: A NEW LOOK AT THE PROTOTYPE DBV
Provencal, J. L.,Montgomery, M. H.,Kanaan, A.,Shipman, H. L.,Childers, D.,Baran, A.,Kepler, S. O.,Reed, M.,Zhou, A.,Eggen, J.,Watson, T. K.,Winget, D. E.,Thompson, S. E.,Riaz, B.,Nitta, A.,Kleinman, S IOP Publishing 2009 The Astrophysical journal Vol.693 No.1
Nanopatterned Human iPSC-Based Model of a Dystrophin-Null Cardiomyopathic Phenotype
Macadangdang, Jesse,Guan, Xuan,Smith, Alec S. T.,Lucero, Rachel,Czerniecki, Stefan,Childers, Martin K.,Mack, David L.,Kim, Deok-Ho Springer-Verlag 2015 Cellular and molecular bioengineering Vol.8 No.3
<P>Human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CMs) offer unprecedented opportunities to study inherited heart conditions in vitro, but are phenotypically immature, limiting their ability to effectively model adult-onset diseases. Cardiomyopathy is becoming the leading cause of death in patients with Duchenne muscular dystrophy (DMD), but the pathogenesis of this disease phenotype is not fully understood. Therefore, we aimed to test whether biomimetic nanotopography could further stratify the disease phenotype of DMD hiPSC-CMs to create more translationally relevant cardiomyocytes for disease modeling applications. We found that anisotropic nanotopography was necessary to distinguish structural differences between normal and DMD hiPSC-CMs, as these differences were masked on conventional flat substrates. DMD hiPSC-CMs exhibited a diminished structural and functional response to the underlying nanotopography compared to normal cardiomyocytes at both the macroscopic and subcellular levels. This blunted response may be due to a lower level of actin cytoskeleton turnover as measured by fluorescence recovery after photobleaching. Taken together these data suggest that DMD hiPSC-CMs are less adaptable to changes in their extracellular environment, and highlight the utility of nanotopographic substrates for effectively stratifying normal and structural cardiac disease phenotypes in vitro.</P>
ENERGY SPECTRA OF COSMIC-RAY NUCLEI AT HIGH ENERGIES
Ahn, H. S.,Allison, P.,Bagliesi, M. G.,Barbier, L.,Beatty, J. J.,Bigongiari, G.,Brandt, T. J.,Childers, J. T.,Conklin, N. B.,Coutu, S.,DuVernois, M. A.,Ganel, O.,Han, J. H.,Jeon, J. A.,Kim, K. C.,Lee, IOP Publishing 2009 The Astrophysical journal Vol.707 No.1
<P>We present new measurements of the energy spectra of cosmic-ray (CR) nuclei from the second flight of the balloon-borne experiment Cosmic-Ray Energetics And Mass (CREAM). The instrument included different particle detectors to provide redundant charge identification and measure the energy of CRs up to several hundred TeV. The measured individual energy spectra of C, O, Ne, Mg, Si, and Fe are presented up to similar to 10(14) eV. The spectral shape looks nearly the same for these primary elements and it can be fitted to an E(-2.66 +/- 0.04)power law in energy. Moreover, a new measurement of the absolute intensity of nitrogen in the 100-800 GeV/n energy range with smaller errors than previous observations, clearly indicates a hardening of the spectrum at high energy. The relative abundance of N/O at the top of the atmosphere is measured to be 0.080 +/- 0.025 (stat.) +/- 0.025 (sys.) at similar to 800 GeV/n, in good agreement with a recent result from the first CREAM flight.</P>
DISCREPANT HARDENING OBSERVED IN COSMIC-RAY ELEMENTAL SPECTRA
Ahn, H. S.,Allison, P.,Bagliesi, M. G.,Beatty, J. J.,Bigongiari, G.,Childers, J. T.,Conklin, N. B.,Coutu, S.,DuVernois, M. A.,Ganel, O.,Han, J. H.,Jeon, J. A.,Kim, K. C.,Lee, M. H.,Lutz, L.,Maestro, P IOP Publishing 2010 ASTROPHYSICAL JOURNAL LETTERS - Vol.714 No.1
<P>The balloon-borne Cosmic Ray Energetics And Mass experiment launched five times from Antarctica has achieved a cumulative flight duration of about 156 days above 99.5% of the atmosphere. The instrument is configured with complementary and redundant particle detectors designed to extend direct measurements of cosmic-ray composition to the highest energies practical with balloon flights. All elements from protons to iron nuclei are separated with excellent charge resolution. Here, we report results from the first two flights of similar to 70 days, which indicate hardening of the elemental spectra above similar to 200 GeV/nucleon and a spectral difference between the two most abundant species, protons and helium nuclei. These results challenge the view that cosmic-ray spectra are simple power laws below the so-called knee at similar to 10(15) eV. This discrepant hardening may result from a relatively nearby source, or it could represent spectral concavity caused by interactions of cosmic rays with the accelerating shock. Other possible explanations should also be investigated.</P>
Provencal, J. L.,Montgomery, M. H.,Kanaan, A.,Thompson, S. E.,Dalessio, J.,Shipman, H. L.,Childers, D.,Clemens, J. C.,Rosen, R.,Henrique, P.,Bischoff-Kim, A.,Strickland, W.,Chandler, D.,Walter, B.,Wat IOP Publishing 2012 The Astrophysical journal Vol.751 No.2
<P>We report on an analysis of 308.3 hr of high-speed photometry targeting the pulsating DA white dwarf EC14012-1446. The data were acquired with the Whole Earth Telescope during the 2008 international observing run XCOV26. The Fourier transform of the light curve contains 19 independent frequencies and numerous combination frequencies. The dominant peaks are 1633.907, 1887.404, and 2504.897 mu Hz. Our analysis of the combination amplitudes reveals that the parent frequencies are consistent with modes of spherical degree l = 1. The combination amplitudes also provide m identifications for the largest amplitude parent frequencies. Our seismology analysis, which includes 2004-2007 archival data, confirms these identifications, provides constraints on additional frequencies, and finds an average period spacing of 41 s. Building on this foundation, we present nonlinear fits to high signal-to-noise light curves from the SOAR 4.1 m, McDonald 2.1 m, and KPNO 2 m telescopes. The fits indicate a time-averaged convective response timescale of tau(0) = 99.4 +/- 17 s, a temperature exponent N = 85 +/- 6.2, and an inclination angle of theta(i) = 32 degrees.9 +/- 3 degrees.2. We present our current empirical map of the convective response timescale across the DA instability strip.</P>