427 research outputs found
Navigating environmental, economic, and technological trade-offs in the design and operation of submerged anaerobic membrane bioreactors (AnMBRs)
Anaerobic membrane bioreactors (AnMBRs) enable energy recovery from wastewater while simultaneously achieving high levels of treatment. The objective of this study was to elucidate how detailed
design and operational decisions of submerged AnMBRs influence the technological, environmental, and
economic sustainability of the system across its life cycle. Specific design and operational decisions
evaluated included: solids retention time (SRT), mixed liquor suspended solids (MLSS) concentration,
sludge recycling ratio (r), flux (J), and specific gas demand per membrane area (SGD). The possibility of
methane recovery (both as biogas and as soluble methane in reactor effluent) and bioenergy production,
nutrient recovery, and final destination of the sludge (land application, landfill, or incineration) were also
evaluated. The implications of these design and operational decisions were characterized by leveraging a
quantitative sustainable design (QSD) framework which integrated steady-state performance modeling
across seasonal temperatures (using pilot-scale experimental data and the simulating software DESASS),
life cycle cost (LCC) analysis, and life cycle assessment (LCA). Sensitivity and uncertainty analyses were
used to characterize the relative importance of individual design decisions, and to navigate trade-offs
across environmental, economic, and technological criteria. Based on this analysis, there are design
and operational conditions under which submerged AnMBRs could be net energy positive and contribute
to the pursuit of carbon negative wastewater treatment.This research work was possible thanks to project CTM2011-28595-C02-01/02 (funded by the Spanish Ministry of Economy and Competitiveness jointly with the European Regional Development Fund and Generalitat Valenciana GVA-ACOMP2013/203), and by the King Abdullah University of Science and Technology (KAUST) Academic Partnership Program (UIeRA 2012-06291), which are gratefully acknowledged. The authors would like also to acknowledge the Jack Kent Cooke Foundation for partial funding for B.D. Shoener.Pretel-Jolis, R.; Shoener, BD.; Ferrer, J.; Guest, J. (2015). Navigating environmental, economic, and technological trade-offs in the design and operation of submerged anaerobic membrane bioreactors (AnMBRs). Water Research. (87):531-541. https://doi.org/10.1016/j.watres.2015.07.002S5315418
Supercurrent flow through an effective double barrier structure
Supercurrent flow is studied in a structure that in the Ginzburg-Landau
regime can be described in terms of an effective double barrier potential. In
the limit of strongly reflecting barriers, the passage of Cooper pairs through
such a structure may be viewed as a realization of resonant tunneling with a
rigid wave function. For interbarrier distances smaller than no
current-carrying solutions exist. For distances between and , four
solutions exist. The two symmetric solutions obey a current-phase relation of
, while the two asymmetric solutions satisfy
for all allowed values of the current. As the distance
exceeds , a new group of four solutions appears, each contaning
soliton-type oscillations between the barriers. We prove the inexistence of a
continuous crossover between the physical solutions of the nonlinear
Ginzburg-Landau equation and those of the corresponding linearized
Schr\"odinger equation. We also show that under certain conditions a repulsive
delta function barrier may quantitatively describe a SNS structure. We are thus
able to predict that the critical current of a SNSNS structure vanishes as
, where is lower than the bulk critical temperature.Comment: 20 pages, RevTex, to appear in Phys. Rev. B, 6 figures on request at
[email protected]
Rapid thermal processing of CuInSe2 electroplated precursors for CuIn(S,Se)2-based thin film solar cells
International audienceDuring the elaboration of standard CISEL™cells, electroplated CuInSe2 precursors undergo a rapid thermal processing (RTP) in a sulfur-containing atmosphere to promote grain growth and enable sulfurization of the precursor. The aim of this work is to show how structural and morphological properties of the CuIn(S,Se)2-based solar cells can be modified with RTP parameters, namely temperature, heating rate, and sulfur addition. X-ray diffractograms show that the preferential (112) orientation of the electrodeposited CuInSe2 precursor is maintained after annealing but the coefficient of crystallographic texture can be modified with specific RTP parameters. It is also shown that the quantity of sulfur incorporated in the chalcopyrite lattice can be controlled and reaches almost pure CuInS2 according to the sulfur quantity used during the RTP. Another effect of the RTP annealing is to form a Mo(S,Se)2 layer which can lead to a quasi-ohmic contact between the molybdenum and the absorber. The properties of the Mo(S,Se)2 buffer layer are also studied according to the process parameters and an increase of the annealing temperature or of the sulfur concentration tends to increase the thickness of this laye
Magnetic Catalysis: A Review
We give an overview of the magnetic catalysis phenomenon. In the framework of
quantum field theory, magnetic catalysis is broadly defined as an enhancement
of dynamical symmetry breaking by an external magnetic field. We start from a
brief discussion of spontaneous symmetry breaking and the role of a magnetic
field in its a dynamics. This is followed by a detailed presentation of the
essential features of the phenomenon. In particular, we emphasize that the
dimensional reduction plays a profound role in the pairing dynamics in a
magnetic field. Using the general nature of underlying physics and its
robustness with respect to interaction types and model content, we argue that
magnetic catalysis is a universal and model-independent phenomenon. In support
of this claim, we show how magnetic catalysis is realized in various models
with short-range and long-range interactions. We argue that the general nature
of the phenomenon implies a wide range of potential applications: from certain
types of solid state systems to models in cosmology, particle and nuclear
physics. We finish the review with general remarks about magnetic catalysis and
an outlook for future research.Comment: 37 pages, to appear in Lect. Notes Phys. "Strongly interacting matter
in magnetic fields" (Springer), edited by D. Kharzeev, K. Landsteiner, A.
Schmitt, H.-U. Yee. Version 2: references adde
Views of the Chiral Magnetic Effect
My personal views of the Chiral Magnetic Effect are presented, which starts
with a story about how we came up with the electric-current formula and
continues to unsettled subtleties in the formula. There are desirable features
in the formula of the Chiral Magnetic Effect but some considerations would lead
us to even more questions than elucidations. The interpretation of the produced
current is indeed very non-trivial and it involves a lot of confusions that
have not been resolved.Comment: 19 pages, no figure; typos corrected, references significantly
updated, to appear in Lect. Notes Phys. "Strongly interacting matter in
magnetic fields" (Springer), edited by D. Kharzeev, K. Landsteiner, A.
Schmitt, H.-U. Ye
Added value of co-morbidity in predicting health-related quality of life in COPD patients
AbstractThe extent to which a chronic obstructive pulmonary disease (COPD) patient is impaired in health-related quality of life (HRQoL) is only to a small extent reflected in clinical and demographical measures. As the influence of co-morbidity on HRQoL is less clear, we investigated the added value of 23 common diseases in predicting HRQoL in COPD patients with mild to severe airways obstruction.COPD patients from general practice who appeared to have an forced expiratory volume in 1 sec/inspiratory vital capacity (FEV1/IVC) < predicted −1·64 SD, FEV1<80% predicted, FEV1reversibility <12% and a smoking history, were included (n=163). HRQoL was assessed with the short-form-36 (SF-36) and the presence of co-morbidity was determined by a questionnaire, which asked for 23 common diseases.All domains of the SF-36 were best predicted by the presence of three or more co-morbid diseases. FEV1% predicted, dyspnoea and the presence of one or two diseases were second-best predictors. Co-morbidity explained an additional part of the variance in HRQoL, particularly for emotional functioning (ΔR2=0·11). When individual diseases were investigated, only insomnia appeared to be related to HRQoL.As HRQoL is still only partly explained, co-morbidity and other patient characteristics do not clearly distinguish between COPD patients with severe impairments in HRQoL and COPD patients with minor or no impairments in HRQoL. Therefore, it remains important to ask for problems in daily functioning and well-being, rather than to rely on patient characteristics alone
Improved tests of extra-dimensional physics and thermal quantum field theory from new Casimir force measurements
We report new constraints on extra-dimensional models and other physics
beyond the Standard Model based on measurements of the Casimir force between
two dissimilar metals for separations in the range 0.2--1.2 m. The Casimir
force between an Au-coated sphere and a Cu-coated plate of a
microelectromechanical torsional oscillator was measured statically with an
absolute error of 0.3 pN. In addition, the Casimir pressure between two
parallel plates was determined dynamically with an absolute error of mPa. Within the limits of experimental and theoretical errors, the results
are in agreement with a theory that takes into account the finite conductivity
and roughness of the two metals. The level of agreement between experiment and
theory was then used to set limits on the predictions of extra-dimensional
physics and thermal quantum field theory. It is shown that two theoretical
approaches to the thermal Casimir force which predict effects linear in
temperture are ruled out by these experiments. Finally, constraints on Yukawa
corrections to Newton's law of gravity are strengthened by more than an order
of magnitude in the range 56 nm to 330 nm.Comment: Revtex 4, 35 pages, 14 figures in .gif format, accepted for
publication in Phys. Rev.
A function-based typology for Earth’s ecosystems
As the United Nations develops a post-2020 global biodiversity framework for the Convention on Biological Diversity, attention is focusing on how new goals and targets for ecosystem conservation might serve its vision of ‘living in harmony with nature’1,2. Advancing dual imperatives to conserve biodiversity and sustain ecosystem services requires reliable and resilient generalizations and predictions about ecosystem responses to environmental change and management3. Ecosystems vary in their biota4, service provision5 and relative exposure to risks6, yet there is no globally consistent classification of ecosystems that reflects functional responses to change and management. This hampers progress on developing conservation targets and sustainability goals. Here we present the International Union for Conservation of Nature (IUCN) Global Ecosystem Typology, a conceptually robust, scalable, spatially explicit approach for generalizations and predictions about functions, biota, risks and management remedies across the entire biosphere. The outcome of a major cross-disciplinary collaboration, this novel framework places all of Earth’s ecosystems into a unifying theoretical context to guide the transformation of ecosystem policy and management from global to local scales. This new information infrastructure will support knowledge transfer for ecosystem-specific management and restoration, globally standardized ecosystem risk assessments, natural capital accounting and progress on the post-2020 global biodiversity framework
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