3,127 research outputs found

    Assessing the influence of the carbon oxidation-reduction state on organic pollutant biodegradation in algal-bacterial photobioreactors

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    The influence of the carbon oxidation-reduction state (CORS) of organic pollutants on their biodegradation in enclosed algal-bacterial photobioreactors was evaluated using a consortium of enriched wild-type methanotrophic bacteria and microalgae. Methane, methanol and glucose (with CORS -4, -2 and 0, respectively) were chosen as model organic pollutants. In the absence of external oxygen supply, microalgal photosynthesis was not capable of supporting a significant methane and methanol biodegradation due to their high oxygen demands per carbon unit, while glucose was fully oxidized by photosynthetic oxygenation. When bicarbonate was added, removal efficiencies of 37¿±¿4% (20 days), 65¿±¿4% (11 days) and 100% (2 days) were recorded for CH(4,) CH(3)OH and C(6)H(12)O(6), respectively due to the additional oxygen generated from photosynthetic bicarbonate assimilation. The use of NO(3)(-) instead of NH(4)(+) as nitrogen source (N oxidation-reduction state of +5 vs. -3) resulted in an increase in CH(4) degradation from 0 to 33¿±¿3% in the absence of bicarbonate and from 37¿±¿4% to 100% in the presence of bicarbonate, likely due to a decrease in the stoichiometric oxygen requirements and the higher photosynthetic oxygen production. Hypothetically, the CORS of the substrates might affect the CORS of the microalgal biomass composition (higher lipid content). However, the total lipid content of the algal-bacterial biomass was 19¿±¿7% in the absence and 16¿±¿2% in the presence of bicarbonat

    Conserved quantities in isotropic loop quantum cosmology

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    We develop an action principle for those models arising from isotropic loop quantum cosmology, and show that there is a natural conserved quantity QQ for the discrete difference equation arising from the Hamiltonian constraint. This quantity QQ relates the semi-classical limit of the wavefunction at large values of the spatial volume, but opposite triad orientations. Moreover, there is a similar quantity for generic difference equations of one parameter arising from a self-adjoint operator.Comment: 6 pages, to be published in Europhysics Letter

    INDICATION OF META-ANTHRACITE BY MAGNETOTELLURICS IN THE KŐSZEG-RECHNITZ PENNINIC WINDOW : A TEST AREA

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    One of the Penninic Nappes is the Kőszeg-Rechnitz (K-R) tectonic window at the Eastern end of the Eastern Alps. It has a complicated metamorphic history from the Jurassic time. The organic material of the Penninic Ocean was transformed to electrically conductive meta-anthracite. Its amount in the chalcophyllite is estimated by geochemists to 0.2 per cent. Taking this conducting structure as a test area pilot deep magnetotelluric (MT) soundings have been carried out and we determined - the structure of the conductivity anomaly due to 0.2 per cent meta anthracite in the K-R window and its surroundings - the different kinds of MT distortions as lateral (side) effect of the conductor appearing in the crust and mantle - the most probable depth of the conductive asthenosphere at the border of the Pannonian Basin (having extreme shallow asthenosphere). The obtained ~140 km depth is in correlation with value of the asthenospheric map based mainly on seismic data

    Social and Economic Impact of Solar Electricity at Schuchuli Village

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    Schuchuli, a small remote village on the Papago Indian Reservation in southwest Arizona, is 27 kilometers (17 miles) from the nearest available utility power. Its lack of conventional power is due to the prohibitive cost of supplying a small electrical load with a long-distance distribution line. Furthermore, alternate energy sources are expensive and place a burden on the resources of the villagers. On December 16, 1978, as part of a federally funded project, a solar cell power system was put into operation at Schuchuli. The system powers the village water pump, lighting for homes and other village buildings, family refrigerators and a communal washing machine and sewing machine

    Characterization of Hardness and Elastic Modulus of a Pharmaceutical Material for Multiple Crystal Orientations

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    Nanoindentation has made it possible to test material properties of extremely brittle molecular crystals, which include many pharmaceuticals. An antifungal, griseofulvin, is tested to determine differences in hardness and elastic modulus for different crystal orientations. Hardness and elastic modulus are determined by nanoindentation on single crystals that are rotated in 15° intervals. There are differences in hardness at rotation degrees of 45°, 60°, and 75° from the 0° orientation and differences in elastic modulus at rotation degrees of 15°, 60°, and 75° from the 0° orientation. It is also found that the elastic modulus and hardness values of the 75° rotation are only similar to the 60° rotation. Griseofulvin displays anisotropy in hardness and elastic modulus, which implies that different crystal rotations activate different slip systems. Further work is needed to correlate rotation angle with the crystal structure as well as confirm these findings on another crystal

    From the discrete to the continuous - towards a cylindrically consistent dynamics

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    Discrete models usually represent approximations to continuum physics. Cylindrical consistency provides a framework in which discretizations mirror exactly the continuum limit. Being a standard tool for the kinematics of loop quantum gravity we propose a coarse graining procedure that aims at constructing a cylindrically consistent dynamics in the form of transition amplitudes and Hamilton's principal functions. The coarse graining procedure, which is motivated by tensor network renormalization methods, provides a systematic approximation scheme towards this end. A crucial role in this coarse graining scheme is played by embedding maps that allow the interpretation of discrete boundary data as continuum configurations. These embedding maps should be selected according to the dynamics of the system, as a choice of embedding maps will determine a truncation of the renormalization flow.Comment: 22 page

    Influence of antisymmetric exchange interaction on quantum tunneling of magnetization in a dimeric molecular magnet Mn6

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    We present magnetization measurements on the single molecule magnet Mn6, revealing various tunnel transitions inconsistent with a giant-spin description. We propose a dimeric model of the molecule with two coupled spins S=6, which involves crystal-field anisotropy, symmetric Heisenberg exchange interaction, and antisymmetric Dzyaloshinskii-Moriya exchange interaction. We show that this simplified model of the molecule explains the experimentally observed tunnel transitions and that the antisymmetric exchange interaction between the spins gives rise to tunneling processes between spin states belonging to different spin multiplets.Comment: 5 pages, 4 figure

    Calibration Methods for Eddy Current Measurement Systems

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    Calibration of eddy current measurement systems is an important factor for attaining the accuracy and precision of measurement that quantitative nondestructive evaluation requires. The quantity of interest in most forms of eddy current inspection is △Z, the change in probe impedance induced by a flaw. Flaw signals produced by surface-breaking cracks are small; typical flaw signals for an air core probe amount to a few tenths of one percent of the probe’s impedance in air. Such small signals are easily obscured by the impedance changes caused by small variations in the height of the probe above the workpiece (lift-off). To discriminate against lift-off, conventional eddy current instruments determine the phase of △Z relative to lift-off and the magnitude of the component of △Z in quadrature with lift-off. But this information is not sufficient to perform flaw signal inversion; rather, the absolute magnitude and phase of △Z are necessary. Thus, quantitative inversion of eddy current signals to obtain flaw sizes requires methods for calibrating eddy current measurement system
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