79 research outputs found
Comparison of three pilot plants filled with organic materials for the treatment of air pollutants from a composting plant
[Abstract] This study has compared the efficiency of 3 mixes of organic materials [peat + coco fibre; branches (1 vol) + wood (1vol) + peat (1 vol.); + branches (5 vol) + wood (2vol) + peat (1 vol.)] used in biofiltres pilot plants in order to remove Volatiles Organic Compounds (VOCs), Ammonia and Odours Units (O.U.) from process and ambient air of a composting plant. After a period of seeding, 3 different air velocities have been applied (125 m/h, 175 m/h and 200 m/h) during approximately 1 œ month each. Results show a better NH3 removal in filters containing wood (92% to 98%) than in the one with coco fibre (between 17% and 63%) depending on the air velocity and on the pollutant concentration (from 35 to 60 ppmV). Concerning VOCs the efficiency was globally the same (approx. 75%) and that for each velocity and for a relatively constant inlet concentration of 20 ppmV Carbon equivalent. Differences are less obvious in terms of Odours Unit that is mainly due to the variability of the analysis itself. The coco fibres filter seems to be a little bit worst than the two others what would be in accordance with the pollutant removal efficiency observed
Revisiting the vortex-core tunnelling spectroscopy in YBaCuO
The observation by scanning tunnelling spectroscopy (STS) of Abrikosov vortex
cores in the high-temperature superconductor YBaCuO (Y123)
has revealed a robust pair of electron-hole symmetric states at finite subgap
energy. Their interpretation remains an open question because theory predicts a
different signature in the vortex cores, characterised by a strong zero-bias
conductance peak. We present STS data on very homogeneous Y123 at 0.4 K
revealing that the subgap features do not belong to vortices: they are actually
observed everywhere along the surface with high spatial and energy
reproducibility, even in the absence of magnetic field. Detailed analysis and
modelling show that these states remain unpaired in the superconducting phase
and belong to an incoherent channel which contributes to the tunnelling signal
in parallel with the superconducting density of states.Comment: Final version with supplementary materia
WET SCRUBBING INTENSIFICATION APPLIED TO HYDROGEN SULPHIDE REMOVAL IN WASTE WATER TREATMENT PLANT
International audienceHydrogen sulphide removal in a Waste Water Treatment Plant at semi-industrial scale in a compact wet scrubber has been investigated. The gas residence time in the scrubber was reduced to 30 ms using a NaOCl caustic scrubbing solution. The contactor is composed of a wire mesh packing structure where liquid and gas flow co-currently at high velocity (> 12 m.s-1). H2S removal percentages higher than 95% could be achieved whereas a moderate pressure drop was measured (< 4000 Pa). Both the hydrodynamic and chemical conditions can influence the efficiency of the process. Correlations were developed to predict both the pressure drop and the H2S removal efficiency at given operating conditions
Traitement de composés organiques volatils par lavage chimique compact: recyclage de la solution de lavage par oxydation avancée O3/H2O2
National audienceThis study focuses on Volatile Organic Compounds (VOC) treatment in a compact chemical scrubber composed of a structured packing operating at co-current and high gas superficial velocity (> 10 m.s-1). The scrubbing liquid is composed of ozone and hydrogen peroxide to generate very reactive hydroxyl radicals. Results demonstrate a high mineralisation rate of the transferred VOC, even with low oxidant concentrations. Therefore, the scrubbing liquid can be recycled and recirculated at the top of the scrubber without efficiency drop over time. Neutral VOC removal efficiency increases with their solubility in water, from 14% for dimethyldisulfide to 86% for butanol using a mass flow rates ratio (L/G) of 2.5 and residence time of 20 ms. For trimethylamine, a basic VOC, the increased apparent solubility at pH = 8 leads to a high removal efficiency of 80%. Major by-products were identified and quantified. An absence of stripping in the treated gas emphasizes their innocuity.Cette Ă©tude porte sur le traitement de ComposĂ©s Organiques Volatils (COV) dans un laveur chimique compact composĂ© dâun garnissage structurĂ© fonctionnant Ă co-courant et Ă vitesse superficielle du gaz Ă©levĂ©e (> 10 m.s-1). La solution aqueuse de lavage se compose dâun mĂ©lange dâozone et de peroxyde dâhydrogĂšne afin de gĂ©nĂ©rer des radicaux hydroxyles trĂšs rĂ©actifs. Les rĂ©sultats dĂ©montrent une minĂ©ralisation poussĂ©e des COV transfĂ©rĂ©s mĂȘme avec des concentrations en oxydants modestes. La solution de lavage peut donc ĂȘtre rĂ©gĂ©nĂ©rĂ©e et rĂ©injectĂ©e en tĂȘte du laveur sans diminution dâefficacitĂ© au cours du temps. Lâabattement en phase gazeuse des COV neutres, observĂ©s pour un rapport des dĂ©bits massiques L/G de 2,5, augmente avec leur solubilitĂ© en phase aqueuse, dĂ©marrant Ă 14% pour le dimethyldisulfide jusquâĂ 86% pour le butanol en 20 ms de temps de contact. Pour la trimĂ©thylamine, composĂ© basique, lâaugmentation de la solubilitĂ© apparente Ă pH 8 permet dâatteindre un abattement Ă©levĂ© de 80%. Les sous-produits majoritaires ont Ă©tĂ© identifiĂ©s et quantifiĂ©s. Lâabsence de stripping dans le gaz traitĂ© met en Ă©vidence leur innocuitĂ©
Hydrogen sulphide removal in waste water treatment plant by compact oxidative scrubbing in Aquilair PlusTM process
International audienceRecently, the development of a high voidage contactor, named Aquilair Plusâą, has demonstrated high efficiency for chemical scrubbing of hydrogen sulphide. Liquid and gas phases flow at co-current and high velocity, leading to a great dispersion of the liquid and then to an enhancement of the mass transfer rate by comparison with classical packed towers. This study focused on the results which obtained at semi-industrial scale with the Aquilair PlusTM process on a waste water treatment plant located in France. The scrubbing liquid consisted of a sodium hypochlorite alkaline solution. At once, pressure drop, H2S removal and reagents consumption were followed. The influence of the superficial gas velocity, liquid-to-gas mass ratio (L/G), pH, hypochlorite concentration of the scrubbing liquid and H2S inlet concentration was characterised. H2S removal percentages higher than 90% could be easily achieved with a moderate pressure drop (< 40 mbar). Both hydrodynamic and chemical conditions proved to influence performances. Reagents consumptions slightly higher than the predicted ones were measured
Vortex-core spectroscopy of -wave cuprate high-temperature superconductors
The mechanism of high-temperature superconductivity remains one of the great
challenges of contemporary physics. Here, we review efforts to image the vortex
lattice in copper oxide-based high-temperature superconductors and to measure
the characteristic electronic structure of the vortex core of a -wave
superconductor using scanning tunneling spectroscopy.Comment: Main text : 7 pages, 8 figure
Scanning tunneling spectroscopy of high-temperature superconductors
Tunneling spectroscopy played a central role in the experimental verification
of the microscopic theory of superconductivity in the classical
superconductors. Initial attempts to apply the same approach to
high-temperature superconductors were hampered by various problems related to
the complexity of these materials. The use of scanning tunneling
microscopy/spectroscopy (STM/STS) on these compounds allowed to overcome the
main difficulties. This success motivated a rapidly growing scientific
community to apply this technique to high-temperature superconductors. This
paper reviews the experimental highlights obtained over the last decade. We
first recall the crucial efforts to gain control over the technique and to
obtain reproducible results. We then discuss how the STM/STS technique has
contributed to the study of some of the most unusual and remarkable properties
of high-temperature superconductors: the unusual large gap values and the
absence of scaling with the critical temperature; the pseudogap and its
relation to superconductivity; the unprecedented small size of the vortex cores
and its influence on vortex matter; the unexpected electronic properties of the
vortex cores; the combination of atomic resolution and spectroscopy leading to
the observation of periodic local density of states modulations in the
superconducting and pseudogap states, and in the vortex cores.Comment: To appear in RMP; 65 pages, 62 figure
Frailty assessment for COVID-19 follow-up: a prospective cohort study.
BACKGROUND
The Clinical Frailty Scale (CFS) is increasingly used for clinical decision making in acute care but little is known about frailty after COVID-19.
OBJECTIVES
To investigate frailty and the CFS for post-COVID-19 follow-up.
METHODS
This prospective multicentre cohort study included COVID-19 survivors aged â„50 years presenting for a follow-up visit â„3 months after the acute illness. Nine centres retrospectively collected pre-COVID-19 CFS and prospectively CFS at follow-up. Three centres completed the Frailty Index (FI), the short physical performance battery (SPPB), 30 s sit-to-stand test and handgrip strength measurements. Mixed effect logistic regression models accounting for repeated measurements and potential confounders were used to investigate factors associated with post-COVID-19 CFS. Criterion and construct validity were determined by correlating the CFS to other concurrently assessed frailty measurements and measures of respiratory impairment, respectively.
RESULTS
Of the 288 participants 65% were men, mean (SD) age was 65.1 (9) years. Median (IQR) CFS at follow-up was 3 (2-3), 21% were vulnerable or frail (CFS â„4). The CFS was responsive to change, correlated with the FI (r=0.69, p<0.001), the SPPB score (r=-0.48, p<0.001) (criterion validity) and with the St George's Respiratory Questionnaire score (r=0.59, p<0.001), forced vital capacity %-predicted (r=-0.25, p<0.001), 6 min walk distance (r=-0.39, p<0.001) and modified Medical Research Council (mMRC) (r=0.59, p<0.001). Dyspnoea was significantly associated with a higher odds for vulnerability/frailty (per one mMRC adjusted OR 2.01 (95% CI 1.13 to 3.58), p=0.02).
CONCLUSIONS
The CFS significantly increases with COVID-19, and dyspnoea is an important risk factor for post-COVID-19 frailty and should be addressed thoroughly
Super-Resolution Dynamic Imaging of Dendritic Spines Using a Low-Affinity Photoconvertible Actin Probe
The actin cytoskeleton of dendritic spines plays a key role in morphological aspects of synaptic plasticity. The detailed analysis of the spine structure and dynamics in live neurons, however, has been hampered by the diffraction-limited resolution of conventional fluorescence microscopy. The advent of nanoscopic imaging techniques thus holds great promise for the study of these processes. We implemented a strategy for the visualization of morphological changes of dendritic spines over tens of minutes at a lateral resolution of 25 to 65 nm. We have generated a low-affinity photoconvertible probe, capable of reversibly binding to actin and thus allowing long-term photoactivated localization microscopy of the spine cytoskeleton. Using this approach, we resolve structural parameters of spines and record their long-term dynamics at a temporal resolution below one minute. Furthermore, we have determined changes in the spine morphology in response to pharmacologically induced synaptic activity and quantified the actin redistribution underlying these changes. By combining PALM imaging with quantum dot tracking, we could also simultaneously visualize the cytoskeleton and the spine membrane, allowing us to record complementary information on the morphological changes of the spines at super-resolution
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