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  • 1
    Electronic Resource
    Electronic Resource
    Experimental diffusion of hydrogen into synthetic fluid inclusions in quartz (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of metamorphic geology 13 (1995), S. 0 
    Details
    ISSN: 1525-1314
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: Abstract Quartz-hosted, synthetic CO2-H2O fluid inclusions behave as open systems with respect to diffusional transfer of hydrogen during laboratory-simulated metamorphic re-equilibration at 650, 750 and 825°C and 1.5 kbar total pressure with fO2 defined by the C-CH4 buffer. Microthermometry and Raman spectroscopy show that the initial CO2-H2O inclusions become CO2-CH4-H2-H2Oinclusions after diffusive influx of hydrogen from the reducing confining medium. Measurable changes are observed in inclusion compositions after only 15 days of re-equilibration, implying significant hydrogen mobility at still lower temperatures over geological time spans. Results of synthetic inclusion re-equilibrium experiments have profound implications for the interpretation of natural fluid-inclusion data; failure to account for potential hydrogen migration in inclusions from high-temperature geological environments may lead to erroneous estimates of P-T, and/or the compositions of metamorphic fluids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1525-1314.1995.tb00224.x
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  • 2
    Electronic Resource
    Electronic Resource
    Fluid inclusion constraints on the uplift history of the metamorphosed massive sulphide deposits at Ducktown, Tennessee (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of metamorphic geology 9 (1991), S. 0 
    Details
    ISSN: 1525-1314
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: Abstract Standard petrographic, microthermometric and Raman spectroscopic analyses of fluid inclusions from the metamorphosed massive sulphide deposits at Ducktown, Tennessee, indicate that fluids with a wide range of compositions in the C–O–H–N–S–salt system were involved in the syn- to post-metamorphic history of these deposits. Primary fluid inclusions from peak metamorphic clinopyroxene contain low-salinity, H2O–CH4 fluids and calcite, quartz and pyrrhotite daughter crystals. Many of these inclusions exhibit morphologies resembling those produced in laboratory experiments in which confining pressures significantly exceed the internal pressures of the inclusions. Secondary inclusions in metamorphic quartz from veins, pods, and host matrix record a complex uplift history involving a variety of fluids in the C–O–H–N–salt system. Early fluids were generated by local devolatilization reactions while later fluids were derived externally.Isochores calculated for secondary inclusions in addition to the chronology of trapping and morphological features of primary and secondary fluid inclusions suggest an uplift path which was concave toward the temperature axis over the P–T range 6–3 kbar and 550–225° C. Immiscible H2O–CH4–N2–NaCl fluids were trapped under lithostatic to hydrostatic pressure conditions at 3–0.5 kbar and 215 ± 20° C. Entrapment occurred during Alleghanian thrusting, and the fluids may have been derived by tectonically driven expulsion of pore fluids and thermal maturation of organic material in lower-plate sedimentary rocks which are thought to underlie the deposits. Episodic fracturing and concomitant pressure decreases in upper-plate rocks, which host the ore bodies, would have allowed these fluids to move upward and become immiscible. Post-Alleghanian uplift appears to have been temperature-convex.Uplift rates of 0.10–0.05 mm year−1 from middle Ordovician to middle Silurian – late Devonian, and 0.07–0.12 mm year−1 from middle Silurian – late Devonian to late Permian are suggested by our uplift path and available geochronological data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1525-1314.1991.tb00548.x
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  • 3
    Electronic Resource
    Electronic Resource
    Synthetic fluid inclusions - VI. Quantitative evaluation of the decrepitation behaviour of fluid inclusions in quartz at one atmosphere confining pressure (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of metamorphic geology 7 (1989), S. 0 
    Details
    ISSN: 1525-1314
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: The decrepitation behaviour of fluid inclusions in quartz at one atmosphere confining pressure has been evaluated using pure H2O synthetic inclusions formed by healing fractures in natural quartz. Three different modes of non-elastic deformation, referred to as stretching, leakage or partial decrepitation, and total decrepitation have been observed. The internal pressure required to initiate non-elastic deformation is inversely related to inclusion size according to the equation:internal pressure (kbar) = 4.26 D-0.423where D is the inclusion diameter in microns. Regularly shaped inclusions require a higher internal pressure to initiate non-elastic deformation than do irregularly shaped inclusions of similar size. Heating inclusions through the α/β quartz inversion results in mechanical instability in the quartz crystal and leads to mass decrepitation of inclusions owing to structural mismatches generated by pressure gradients in the quartz around each inclusion.Long-term heating experiments (∼2 years) suggest that the internal pressure required to initiate non-elastic deformation does not decrease significantly with time and indicates that short-lived thermal fluctuations in natural systems should not alter the inclusion density and homogenization temperature. Inclusions that do exhibit decreased density (higher homogenization temperature) are, however, always accompanied by a change in shape from irregular to that of a negative crystal.Observations of this study are consistent with elasticity theory related to fracture generation and propagation around inclusions in minerals. These results indicate that an inclusion will not be influenced by a neighbouring inclusion, or other defect in the host phase, as long as the distance between the two is 〉2–4 diameters of the larger of the two inclusions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1525-1314.1989.tb00586.x
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  • 4
    Electronic Resource
    Electronic Resource
    Combustion Synthesis and Characterization of Nanocrystalline Tin and Tin Oxide (SnOx, x= 0–2) Particles (2004)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Ceramic Society 87 (2004), S. 0 
    Details
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Nanocrystalline SnOx particles (x= 0–2) were synthesized using tetramethyltin (Sn(CH3)4) vapor as the particle precursor reactant in hydrogen/oxygen/argon (H2/O2/Ar) flames. The particle composition and morphology were characterized using X-ray diffractometry, transmission electron microscopy, and nitrogen (N2) surface adsorption. By controlling the concentration of oxygen in the reactant gases and the flame temperatures, metallic tin (Sn), tin monoxide (romarchite SnO), and/or tin dioxide (cassiterite SnO2) were generated. The crystalline powders consisted of both discrete primary particles and agglomerates, with average primary particle sizes of 23–24 nm for SnO2 and 69 nm for Sn (based on specific surface area measurements of bulk powders collected in the exhaust region of the flame). The compositional results were interpreted using equilibrium and detailed chemical kinetics models.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.2004.tb06356.x
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  • 5
    Electronic Resource
    Electronic Resource
    The use of angles and angular rates (1977)
    Springer
    Celestial mechanics and dynamical astronomy 16 (1977), S. 481-488 
    Details
    ISSN: 1572-9478
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract MIT's Lincoln Laboratory has developed a computer driven, rapidly slewing (≃4° s−1), electro-optical (≃3″ resolution) telescope. This enables the rapid measurement of angles and instantaneous angular rates for artificial satellites. The simultaneous acquisition of angles and angular rates constitutes a new initial orbit problem which has been solved. Three different methods of solution are presented including an exact, analytical one. Numerical tests on six widely different satellite orbits indicate that the topocentric distance can be determined to better than 1% (and usually as well as 0.1%) for most satellites after a 5–10 min observation interval.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01229289
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  • 6
    Electronic Resource
    Electronic Resource
    The use of angles and angular rates (1980)
    Springer
    Celestial mechanics and dynamical astronomy 21 (1980), S. 281-290 
    Details
    ISSN: 1572-9478
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Earlier work on the angles and angular rate initial orbit determination problem has been extended to allow the incorporation of arbitrary amounts and mixtures of angles and angular rate data. The statistical estimation technique used is that of Maximum Likelihood. Numerical tests on six widely different satellite orbits indicate that the orbital elements can generally be computed to 1% from data acquired during a single apparition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01230226
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  • 7
    Electronic Resource
    Electronic Resource
    Analyses of sidereal and solar anisotropies in cosmic rays (1996)
    Springer
    Space science reviews 78 (1996), S. 401-442 
    Details
    ISSN: 1572-9672
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The Sun's interplanetary magnetic field and the solar wind modulate the distribution of galactic cosmic-ray particles in the heliosphere. The particles diffuse inward, convert outward and have drifts in the motion of their gyro-centres. Irregularities in the IMF also scatter particles from their gyro-orbits. These processes are the components of solar modulation and produce streaming (and higher-order anisotropies) of particles in the heliosphere. The anisotropies can be investigated at the Earth by examining the count rates of cosmic-ray detectors. The anisotropic streams appear as diurnal variations in solar and sidereal time in the count rates. Higher-order anisotropies produce generally much smaller semi-diurnal and higher-order variations. Theoretical models of solar modulation predict effects that depend on the polarity of the Sun's magnetic dipole. The solar diurnal and north-south anisotropies can be used to test these predictions. This paper is a short review of analyses of 60 years of cosmic-ray data collected at the Earth for the solar and sidereal diurnal variations present. Past analyses have yielded interesting and controversial results regarding the rigidity spectra and components of these anisotropies. Some of the controversy remains today. Analyses of these anisotropies have also yielded quantitative information about parameters important to solar modulation, such as latitudinal and radial density gradients. The relatively new techniques used for these determinations are explained here. Calculations of these modulation parameters from Earth-based cosmic-ray detectors are reviewed and compared to spaceprobe measurements and theoretical predictions of their values. Recently, investigations of the sidereal and solar diurnal anisotropies have been combined to calculate mean-free-paths of cosmic rays in the heliosphere. The latest conclusions from these analyses are that the parallel mean-free-paths of cosmic rays may depend on the polarity of the Sun's magnetic field. The results of these investigations are included in this paper to indicate the present state of knowledge concerning this facet of cosmic-ray research.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00171926
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  • 8
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    Proof-of-principle demonstration of Nb3Sn superconducting radiofrequency cavities for high Q0 applications (2015)
    American Institute of Physics
    Details
    Publication Date: 2015-02-23
    Print ISSN: 0003-6951
    Electronic ISSN: 1077-3118
    Topics: Physics
    Published by American Institute of Physics
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  • 9
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    Constraining Groundwater Flow in the Glacial Drift and Saginaw Aquifers in the Michigan Basin through Helium Concentrations and Isotopic Ratios (2015)
    Wiley
    In: Geofluids
    Details
    Publication Date: 2015-02-26
    Description: 3 He and 4 He concentrations in excess of those in water in solubility equilibrium with the atmosphere by up to two and three orders of magnitude are observed in the shallow Glacial Drift and Saginaw aquifers in the Michigan Basin. A simplified He transport model shows that in-situ production is negligible and that most He excesses have a source external to the aquifer. Simulated results show that 3 He and 4 He fluxes entering the bottom of the Saginaw aquifer are 7.5×10 -14 and 6.1×10 -7 cm 3 STPcm −2 yr −1 , both of which are lower than fluxes entering the underlying Marshall aquifer, 1.0×10 -13 and 1.6×10 -6 cm 3 STPcm −2 yr −1 for 3 He and 4 He, respectively. In contrast, He fluxes entering the Saginaw aquifer are higher than fluxes entering the overlying Glacial Drift aquifer of 5.2×10 -14 and 1.5 × 10 -7 cm 3 STPcm −2 yr −1 for 3 He and 4 He, respectively. The unusually high He fluxes and their decreasing values from the lower Marshall to the upper Glacial Drift aquifer strongly suggest the presence of an upward cross-formational flow, with increasing He dilution toward the surface by recharge water. These fluxes are either comparable to or far greater than He fluxes in deeper aquifers around the world. Model simulations also suggest an exponential decrease of the horizontal groundwater velocity with recharge distance. Horizontal velocities vary from 13 to 2 myr −1 for the Saginaw aquifer and from 18 to 6 myr −1 for the Marshall aquifer. The highly permeable Glacial Drift aquifer displays a greater velocity range, from 250 to 5 myr −1 . While Saginaw 4 He ages estimated based on the simulated velocity field display an overall agreement with 14 C ages, 14 C and 4 He ages in the Glacial Drift and Marshall aquifers deviate significantly, possibly due to simplifications introduced in the He transport model leading to calculation of first order approximation He ages and high uncertainties in Glacial Drift 14 C ages. This article is protected by copyright. All rights reserved.
    Print ISSN: 1468-8115
    Electronic ISSN: 1468-8123
    Topics: Geosciences
    Published by Wiley
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  • 10
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    Top-Down Estimates of NOx and CO Emissions From Washington, D.C.-Baltimore During the WINTER Campaign (2018)
    American Geophysical Union
    Details
    Publication Date: 2018-07-23
    Description: Airborne mass balance experiments were conducted around the Washington, D.C.‐Baltimore area using research aircraft from Purdue University and the University of Maryland to quantify emissions of nitrogen oxides (NOx = NO + NO2) and carbon monoxide (CO). The airborne mass balance experiments supported the Wintertime INvestigation of Transport, Emissions, and Reactivity (WINTER) campaign, an intensive airborne study of anthropogenic emissions along the Northeastern United States in February–March 2015, and the Fluxes of Atmospheric Greenhouse Gases in Maryland project which seeks to provide best estimates of anthropogenic emissions from the Washington, D.C.‐Baltimore area. Top‐down emission rates of NOx and CO estimated from the mass balance flights are compared with the Environmental Protection Agency's 2011 and 2014 National Emissions Inventory (NEI‐11 and NEI‐14). Inventory and observation‐derived NOx emission rates are consistent within the measurement uncertainty. Observed CO emission rates are a factor of 2 lower than reported by the NEI. The NEI's accuracy has been evaluated for decades by studies of anthropogenic emissions, yet despite continuous inventory updates, observation‐inventory discrepancies persist. WINTER NOx/CO2 enhancement ratios are consistent with inventories, but WINTER CO/NOx and CO/CO2 enhancement ratios are lower than those reported by other urban summertime studies, suggesting a strong influence of CO seasonal trends and/or nationwide CO reductions. There is a need for reliable observation‐based criterion pollutant emission rate measurements independent of the NEI. Such determinations could be supplied by the community's reporting of sector‐specific criteria pollutant/CO2 enhancement ratios and subsequent multiplication with currently available and forthcoming high‐resolution CO2 inventories.
    Print ISSN: 2169-897X
    Electronic ISSN: 2169-8996
    Topics: Geosciences , Physics
    Published by American Geophysical Union
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