4,611 research outputs found
Use of Desulfovibrio and Escherichia coli Pd-nanocatalysts in reduction of Cr(VI) and hydrogenolytic dehalogenation of polychlorinated biphenyls and used transformer oil
BACKGROUND Desulfovibrio spp. biofabricate metallic nanoparticles (e.g. ‘Bio-Pd’) which catalyse the reduction of Cr(VI) to Cr(III) and dehalogenate polychlorinated biphenyls (PCBs). Desulfovibrio spp. are anaerobic and produce H2S, a potent catalyst poison, whereas Escherichia coli can be pre-grown aerobically to high density, has well defined molecular tools, and also makes catalytically-active ‘Bio-Pd’. The first aim was to compare ‘Bio-Pd’ catalysts made by Desulfovibrio spp. and E. coli using suspended and immobilised catalysts. The second aim was to evaluate the potential for Bio-Pd-mediated dehalogenation of PCBs in used transformer oils, which preclude recovery and re-use.\ud
RESULTS Catalysis via Bio-PdD. desulfuricans and Bio-PdE. coli was compared at a mass loading of Pd:biomass of 1:3 via reduction of Cr(VI) in aqueous solution (immobilised catalyst) and hydrogenolytic release of Cl- from PCBs and used transformer oil (catalyst suspensions). In both cases Bio-PdD. desulfuricans outperformed Bio-Pd E. coli by ~3.5-fold, attributable to a ~3.5-fold difference in their Pd-nanoparticle surface areas determined by magnetic measurements (Bio-PdD. desulfuricans) and by chemisorption analysis (Bio-PdE. coli). Small Pd particles were confirmed on D. desulfuricans and fewer, larger ones on E. coli via electron microscopy. Bio-PdD. desulfuricans-mediated chloride release from used transformer oil (5.6 0.8 g mL-1 ) was comparable to that observed using several PCB reference materials. \ud
CONCLUSIONS At a loading of 1:3 Pd: biomass Bio-PdD. desulfuricans is 3.5-fold more active than Bio-PdE. coli, attributable to the relative catalyst surface areas reflected in the smaller nanoparticle sizes of the former. This study also shows the potential of Bio-PdD. desulfuricans to remediate used transformer oil
In vitro co-culture of Solanum tuberosum hairy roots with Meloidogyne chitwoodi: structure, growth and production of volatiles
Meloidogyne spp., commonly known as root- knot nematodes (RKNs), are economically important plant sedentary endoparasites that cause galls on susceptible hosts. The Columbia root-knot nematode (CRKN), M. chitwoodi, is a quarantine A2 type pest by the European and Mediterranean Plant Protection Organization since 1998. This nematode has been found associated with economi- cally important crops such as potato and tomato, causing severe damage and making the agricultural products unac- ceptable for the fresh market and food processing. In vitro co-culture of host and parasite offers an advantageous experimental system for studying plant-RKN interactions. The structure, growth and production of volatiles of Sola- num tuberosum hairy roots (HR) and of S. tuberosum HR/ CRKN co-cultures were compared. HR were induced by inoculation of aseptic potato tuber segments with Rhizo- bium rhizogenes. Co-cultures were initiated by inoculating HR with sterilized CRKN eggs. Infection with CRKN induced the RKN symptomatology in the HR and several nematode life stages were observed by light and scanning electron microscopy. Potato HR and HR/CRKN co-culturesexhibited similar growth patterns, evaluated by measuring fresh and dry weight and by the dissimilation method. Volatiles, isolated by distillation–extraction and analyzed by gas chromatography (GC) and gas chromatography coupled to mass spectrometry, revealed that palmitic acid (37–52 %), n–pentadecanal (10–16 %) and linoleic acid (2–16 %) were the main constitutive components of S. tu- berosum HR, and of the HR/CRKN co-cultures (24–44, 8–22 and 4–18 %, respectively). S. tuberosum HR/CRKN co-cultures can be considered a suitable biotechnological tool to study RKN infection mechanism by mimicking what occurs under field conditions
Measurements in two bases are sufficient for certifying high-dimensional entanglement
High-dimensional encoding of quantum information provides a promising method
of transcending current limitations in quantum communication. One of the
central challenges in the pursuit of such an approach is the certification of
high-dimensional entanglement. In particular, it is desirable to do so without
resorting to inefficient full state tomography. Here, we show how carefully
constructed measurements in two bases (one of which is not orthonormal) can be
used to faithfully and efficiently certify bipartite high-dimensional states
and their entanglement for any physical platform. To showcase the practicality
of this approach under realistic conditions, we put it to the test for photons
entangled in their orbital angular momentum. In our experimental setup, we are
able to verify 9-dimensional entanglement for a pair of photons on a
11-dimensional subspace each, at present the highest amount certified without
any assumptions on the state.Comment: 11+14 pages, 2+7 figure
Intrinsic and Extrinsic Performance Limits of Graphene Devices on SiO2
The linear dispersion relation in graphene[1,2] gives rise to a surprising
prediction: the resistivity due to isotropic scatterers (e.g. white-noise
disorder[3] or phonons[4-8]) is independent of carrier density n. Here we show
that acoustic phonon scattering[4-6] is indeed independent of n, and places an
intrinsic limit on the resistivity in graphene of only 30 Ohm at room
temperature (RT). At a technologically-relevant carrier density of 10^12 cm^-2,
the mean free path for electron-acoustic phonon scattering is >2 microns, and
the intrinsic mobility limit is 2x10^5 cm^2/Vs, exceeding the highest known
inorganic semiconductor (InSb, ~7.7x10^4 cm^2/Vs[9]) and semiconducting carbon
nanotubes (~1x10^5 cm^2/Vs[10]). We also show that extrinsic scattering by
surface phonons of the SiO2 substrate[11,12] adds a strong temperature
dependent resistivity above ~200 K[8], limiting the RT mobility to ~4x10^4
cm^2/Vs, pointing out the importance of substrate choice for graphene
devices[13].Comment: 16 pages, 3 figure
Long-lived stops in MSSM scenarios with a neutralino LSP
This work investigates the possibility of a long-lived stop squark in
supersymmetric models with the neutralino as the lightest supersymmetric
particle (LSP). We study the implications of meta-stable stops on the sparticle
mass spectra and the dark matter density. We find that in order to obtain a
sufficiently long stop lifetime so as to be observable as a stable R-hadron at
an LHC experiment, we need to fine tune the mass degeneracy between the stop
and the LSP considerably. This increases the stop-neutralino coanihilation
cross section, leaving the neutralino relic density lower than what is expected
from the WMAP results for stop masses ~1.5 TeV/c^2. However, if such scenarios
are realised in nature we demonstrate that the long-lived stops will be
produced at the LHC and that stop-based R-hadrons with masses up to 1 TeV/c^2
can be detected after one year of running at design luminosity
Returning to spiritual sense: cruciform power and queer identities in analytic theology
In recent theological scholarship, there has been a wave of interest in the tradition of spiritual sense and marginal social identities within analytic and philosophical theology. In this article, I explore the theologies of spiritual sense in analytic theology (AT) to highlight part of the reason for the predominance of cisgender heterosexual voices in the field. Many feminist voices in AT express a common concern for a lack of integration between the mind, the body, and spiritual sense, which has enshrined the post-enlightenment cisgender heterosexual ‘man of reason’. Through an exploration of these feminist voices (Sarah Coakley and Michelle Panchuk), I argue that the field does not simply need more diverse voices but also voices of spiritual sense that undo a straight cisgender elitism. This elitism has kept the field from widely examining the anthropological questions of sexuality and gender, ethics, and theodicean dilemmas of desire and faith. By opening analytic philosophical approaches to spiritual sense, the field releases noetic control that has two consequential outcomes. Firstly, the field revalorizes pneumatology and ethics. Secondly, as a consequence of this, the field can see those who were previously unseen and heard, and, therefore, AT can develop into a sensing and thinking discipline capable of perceiving the queer or other in its midst. Spiritual sense and its priority for bodily and cruciform realities of suffering and desire can move the field from homogeneity to embracing the diverse ethical concerns of sexuality, gender, and race, and subaltern or queer subjectivities which are yet to be represented well in its midst. Using a distinctly neo-Augustinian approach, I argue that Augustine’s philosophy of the amor dei, with its emphasis on analytic clarity and inner spiritual sense, can redeem the eyes of AT’s heart
Second law, entropy production, and reversibility in thermodynamics of information
We present a pedagogical review of the fundamental concepts in thermodynamics
of information, by focusing on the second law of thermodynamics and the entropy
production. Especially, we discuss the relationship among thermodynamic
reversibility, logical reversibility, and heat emission in the context of the
Landauer principle and clarify that these three concepts are fundamentally
distinct to each other. We also discuss thermodynamics of measurement and
feedback control by Maxwell's demon. We clarify that the demon and the second
law are indeed consistent in the measurement and the feedback processes
individually, by including the mutual information to the entropy production.Comment: 43 pages, 10 figures. As a chapter of: G. Snider et al. (eds.),
"Energy Limits in Computation: A Review of Landauer's Principle, Theory and
Experiments
Motivation and incentives of rural maternal and neonatal health care providers: a comparison of qualitative findings from Burkina Faso, Ghana and Tanzania.
In Burkina Faso, Ghana and Tanzania strong efforts are being made to improve the quality of maternal and neonatal health (MNH) care. However, progress is impeded by challenges, especially in the area of human resources. All three countries are striving not only to scale up the number of available health staff, but also to improve performance by raising skill levels and enhancing provider motivation. In-depth interviews were used to explore MNH provider views about motivation and incentives at primary care level in rural Burkina Faso, Ghana and Tanzania. Interviews were held with 25 MNH providers, 8 facility and district managers, and 2 policy-makers in each country. Across the three countries some differences were found in the reasons why people became health workers. Commitment to remaining a health worker was generally high. The readiness to remain at a rural facility was far less, although in all settings there were some providers that were willing to stay. In Burkina Faso it appeared to be particularly difficult to recruit female MNH providers to rural areas. There were indications that MNH providers in all the settings sometimes failed to treat their patients well. This was shown to be interlinked with differences in how the term 'motivation' was understood, and in the views held about remuneration and the status of rural health work. Job satisfaction was shown to be quite high, and was particularly linked to community appreciation. With some important exceptions, there was a strong level of agreement regarding the financial and non-financial incentives that were suggested by these providers, but there were clear country preferences as to whether incentives should be for individuals or teams. Understandings of the terms and concepts pertaining to motivation differed between the three countries. The findings from Burkina Faso underline the importance of gender-sensitive health workforce planning. The training that all levels of MNH providers receive in professional ethics, and the way this is reinforced in practice require closer attention. The differences in the findings across the three settings underscore the importance of in-depth country-level research to tailor the development of incentives schemes
Variable influence of photosynthetic thermal acclimation on future carbon uptake in Australian wooded ecosystems under climate change.
Climate change will impact gross primary productivity (GPP), net primary productivity (NPP), and carbon storage in wooded ecosystems. The extent of change will be influenced by thermal acclimation of photosynthesis-the ability of plants to adjust net photosynthetic rates in response to growth temperatures-yet regional differences in acclimation effects among wooded ecosystems is currently unknown. We examined the effects of changing climate on 17 Australian wooded ecosystems with and without the effects of thermal acclimation of C3 photosynthesis. Ecosystems were drawn from five ecoregions (tropical savanna, tropical forest, Mediterranean woodlands, temperate woodlands, and temperate forests) that span Australia's climatic range. We used the CABLE-POP land surface model adapted with thermal acclimation functions and forced with HadGEM2-ES climate projections from RCP8.5. For each site and ecoregion we examined (a) effects of climate change on GPP, NPP, and live tree carbon storage; and (b) impacts of thermal acclimation of photosynthesis on simulated changes. Between the end of the historical (1976-2005) and projected (2070-2099) periods simulated annual carbon uptake increased in the majority of ecosystems by 26.1%-63.3% for GPP and 15%-61.5% for NPP. Thermal acclimation of photosynthesis further increased GPP and NPP in tropical savannas by 27.2% and 22.4% and by 11% and 10.1% in tropical forests with positive effects concentrated in the wet season (tropical savannas) and the warmer months (tropical forests). We predicted minimal effects of thermal acclimation of photosynthesis on GPP, NPP, and carbon storage in Mediterranean woodlands, temperate woodlands, and temperate forests. Overall, positive effects were strongly enhanced by increasing CO2 concentrations under RCP8.5. We conclude that the direct effects of climate change will enhance carbon uptake and storage in Australian wooded ecosystems (likely due to CO2 enrichment) and that benefits of thermal acclimation of photosynthesis will be restricted to tropical ecoregions
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