51 research outputs found

    Membrane Process for Biological Treatment of Contaminated Gas Streams

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    A Hollow Fiber Membrane Bioreactor Was Investigated for Control of Air Emissions of Biodegradable Volatile Organic Compounds (VOCs). in the Membrane Bioreactor, Gases Containing VOCs Pass through the Lumen of Microporous Hydrophobic Hollow Fiber Membranes. Soluble Compounds Diffuse through the Membrane Pores and Partition into a VOC Degrading Biofilm. the Hollow Fiber Membranes Serve as a Support for the Microbial Population and Provide a Large Surface Area for VOC and Oxygen Mass Transfer. Experiments Were Performed to Investigate the Effects of Toluene Loading Rate, Gas Residence Time, and Liquid Phase Turbulence on Toluene Removal in a Laboratory-Scale Membrane Bioreactor. Initial Acclimation of the Microbial Culture to Toluene Occurred over a Period of Nine Days, after Which a 70% Removal Efficiency Was Achieved at an Inlet Toluene Concentration of 200 Ppm and a Gas Residence Time of 1.8 S (Elimination Capacity of 20 G M-3 Min-1). at Higher Toluene Loading Rates, a Maximum Elimination Capacity of 42 G M-3 Min-1 Was Observed. in the Absence of a Biofilm (Abiotic Operation), Mass Transfer Rates Were Found to Increase with Increasing Liquid Recirculation Rates. Abiotic Mass Transfer Coefficients Could Be Estimated using a Correlation of Dimensionless Parameters Developed for Heat Transfer. Liquid Phase Recirculation Rate Had No Effect on Toluene Removal When the Biofilm Was Present, However. Three Models of the Reactor Were Created: A Numeric Model, a First-Order Flat Sheet Model, and a Zero-Order Flat Sheet Model. Only the Numeric Model Fit the Data Well, Although Removal Predicted as a Function of Gas Residence Time Disagreed Slightly with that Observed. a Modification in the Model to Account for Membrane Phase Resistance Resulted in an Underprediction of Removal. Sensitivity Analysis of the Numeric Model Indicated that Removal Was a Strong Function of the Liquid Phase Biomass Density and Biofilm Diffusion Coefficient, with Diffusion Rates Below 10-9 M2 S-1 Resulting in Decreased Removal Rates

    Stationary Dyonic Regular and Black Hole Solutions

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    We consider globally regular and black hole solutions in SU(2) Einstein-Yang-Mills-Higgs theory, coupled to a dilaton field. The basic solutions represent magnetic monopoles, monopole-antimonopole systems or black holes with monopole or dipole hair. When the globally regular solutions carry additionally electric charge, an angular momentum density results, except in the simplest spherically symmetric case. We evaluate the global charges of the solutions and their effective action, and analyze their dependence on the gravitational coupling strength. We show, that in the presence of a dilaton field, the black hole solutions satisfy a generalized Smarr type mass formula.Comment: 23 pages, 4 figure

    Thermodynamic analysis of the Quantum Critical behavior of Ce-lattice compounds

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    A systematic analysis of low temperature magnetic phase diagrams of Ce compounds is performed in order to recognize the thermodynamic conditions to be fulfilled by those systems to reach a quantum critical regime and, alternatively, to identify other kinds of low temperature behaviors. Based on specific heat (CmC_m) and entropy (SmS_m) results, three different types of phase diagrams are recognized: i) with the entropy involved into the ordered phase (SMOS_{MO}) decreasing proportionally to the ordering temperature (TMOT_{MO}), ii) those showing a transference of degrees of freedom from the ordered phase to a non-magnetic component, with their Cm(TMO)C_m(T_{MO}) jump (ΔCm\Delta C_m) vanishing at finite temperature, and iii) those ending in a critical point at finite temperature because their ΔCm\Delta C_m do not decrease with TMOT_{MO} producing an entropy accumulation at low temperature. Only those systems belonging to the first case, i.e. with SMO→0S_{MO}\to 0 as TMO→0T_{MO}\to 0, can be regarded as candidates for quantum critical behavior. Their magnetic phase boundaries deviate from the classical negative curvature below T≈2.5T\approx 2.5\,K, denouncing frequent misleading extrapolations down to T=0. Different characteristic concentrations are recognized and analyzed for Ce-ligand alloyed systems. Particularly, a pre-critical region is identified, where the nature of the magnetic transition undergoes significant modifications, with its ∂Cm/∂T\partial C_m/\partial T discontinuity strongly affected by magnetic field and showing an increasing remnant entropy at T→0T\to 0. Physical constraints arising from the third law at T→0T\to 0 are discussed and recognized from experimental results

    The Developmental Significance of Adolescent Romantic Relationships: Parent and Peer Predictors of Engagement and Quality at Age 15

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    From a longitudinal sample (n = 957; 49.9% male; 77.3% White/non-Hispanic) of participants studied from infancy through age 15, adolescents’ depth of engagement in, and quality of romantic relationships were predicted from early and contemporaneous parent–child interactive quality and peer social competence. High quality maternal parenting and peer experiences prior to and during adolescence tended to be negatively associated with the depth of engagement in this domain for the full sample, yet positively associated with the quality of adolescents’ romantic relationships for the sub-set of individuals currently dating at age 15. Results reconcile contrasting views of the origins of romantic relationship engagement and quality and the positive versus negative developmental salience of romantic relationships in adolescence

    Effects of Attractiveness and Social Status on Dating Desire in Heterosexual Adolescents: An Experimental Study

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    The present study examined to what extent adolescent dating desire is based on attractiveness and social status of a potential short-term partner. Further, we tested whether self-perceived mate value moderated the relationship between dating desire and attractiveness of a potential partner. Data were used from a sample of 1,913 adolescents aged 13–18. Participants rated the importance of various characteristics of a potential partner and also participated in an experimental vignette study in which dating desire was measured with either low or high attractive potential partners having either a high or low social status. The results showed that boys rated attractiveness as more important than girls, while social status was rated as relatively unimportant by both sexes. In addition, in the experimental vignette study, it was found that attractiveness was the primary factor for boys’ dating desire. Only when a potential partner was attractive, social status became important for boys’ dating desire. For girls, on the other hand, it appeared that both attractiveness and social status of a potential partner were important for their dating desire. Finally, boys and girls who perceived themselves as having a high mate value showed more dating desire toward an attractive potential partner compared to adolescents who perceived themselves as having a low mate value. The present results extend previous research by showing that attractiveness of a potential partner is important to both adolescent boys and girls, but social status does not strongly affect dating desire during this particular age period

    Relation of Hope to Self-Perception

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    Simulations of a cold-air pool associated with elevated wintertime ozone in the Uintah Basin, Utah

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    Numerical simulations are used to investigate the meteorological characteristics of the 31 January–6 February 2013 cold-air pool in the Uintah Basin, Utah, and the resulting high ozone concentrations. Flow features affecting cold-air pools and air quality in the Uintah Basin are studied, including the following: penetration of clean air into the basin from across the surrounding mountains, elevated easterlies within the inversion layer, and thermally driven slope and valley flows. The sensitivity of the boundary layer structure to snow cover variations and cloud microphysics are also examined. Snow cover increases boundary layer stability by enhancing the surface albedo, reducing the absorbed solar insolation at the surface, and lowering near-surface air temperatures. Snow cover also increases ozone levels by enhancing solar radiation available for photochemical reactions. Ice-dominant clouds enhance cold-air pool strength compared to liquid-dominant clouds by increasing nocturnal cooling and decreasing longwave cloud forcing

    Erfolg durch NÀhe zu internen und externen Partnern: Erfolgsfaktoren im Technologiemanagement - Teil 6. Interne Netzwerke, NÀhe zu Konsumenten und kurze Kommunikationswege. Diese drei Faktoren fördern ein marktnahes Technologiemanagement

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    Vernetzung durch persönliche Kontakte und direkten Austausch - so lautet ein Erfolgsfaktor, den das Fraunhofer-Institut fĂŒr Produktionstechnologie IPT in einem Konsortial-Benchmarking identifizierte. Die Beiersdorf AG setzt dies hervorragend um und baut so eine BrĂŒcke vom Technologiemanagement zu den VerbraucherwĂŒnschen. Das Unternehmen legt besonderen Wert auf NĂ€he zum Konsumenten, baut gezielt interne Netzwerke auf und bindet eine Vielzahl externer Partner sehr eng in die Technologie- und Produktentwicklung ein (Integrated Innovation Management - IIM). Deshalb wurde das Unternehmen als eines der fĂŒnf Besten im Technologiemanagement ausgezeichnet. Der IIM-Prozess ist ein mehrstufiger Stage-Gate-Prozess, in den neben den Technologen und Produktentwicklern auch das Marketing, die Marktforschung und die Supply Chain eingebunden sind. Durch den Open-Innovation-Ansatz wird die Zusammenarbeit mit externen Partnern (ParfĂŒmhersteller) intensiviert, mit dem Ziel DĂŒfte zu evaluieren und gemeinsame Projekte besser zu koordinieren. Die genannten Aspekte zeigen, dass erfolgreiches Technologiemanagement nicht allein darauf aufbaut, die richtigen formalen Prozesse und Strukturen im Unternehmen zu realisieren; vielmehr mĂŒssen die Elemente des Technologiemanagements berĂŒcksichtigen welche Formen der Zusammenarbeit im Unternehmen vorliegen, durch welche Werte diese geprĂ€gt sind und was gewohnte Wege der Kommunikation im Unternehmen sind
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