220 research outputs found
The Trillion Dollar Question: Tracking Public and Private Investment in Transport
This paper attempts to quantify capital investment in transport around the world. Distinguishing public and private investment at the national and international level is the first step needed to shift investment towards more sustainable, low-carbon modes and systems
Terres excavées : benchmark européen et élaboration d'une méthodologie française de gestion
National audienceLes différents acteurs français de l'aménagement du territoire et du renouvellement urbain, qu'ils soient institutionnels ou privés, sont confrontés à la difficulté de gestion des terres excavées. Il est ainsi nécessaire de définir des règles et des méthodes visant à encadrer la réutilisation durable des terres dans des conditions garantissant la protection de la santé humaine et de l'environnement. Pour préciser ces règles et fournir aux différents acteurs un cadre commun et directement applicable, le Ministère du développement durable a missionné le BRGM et l'INERIS pour construire un guide méthodologique pour la valorisation des terres excavées en techniques routières et sur des projets d'aménagement. La réalisation de ce guide méthodologique s'appuie sur différents groupes de travail constitués d'un large panel d'acteurs du domaine (associations professionnelles, association de protection de l'environnement, aménageurs, avocats...). Les travaux associés à l'élaboration du guide porte sur la définition de valeurs seuils issues de la prise en compte du risque d'exposition des personnes et de la préservation de la qualité des eaux souterraines. L'élaboration du guide intègre un bench-marking avec les travaux similaires dans les autres pays européens et notamment aux Pays-Bas (ce bench-marking est présenté dans le résumé : " retour d'expérience de la gestion des terres excavées dans les pays de l'Union européenne et notamment aux Pays-Bas et en Angleterre "). L'intervention portera sur : - La présentation du guide en l'état - La présentation des premiers résultats
Intrusion and extrusion of water in hydrophobic mesopores
We present experimental and theoretical results on intrusion-extrusion cycles
of water in hydrophobic mesoporous materials, characterized by independent
cylindrical pores. The intrusion, which takes place above the bulk saturation
pressure, can be well described using a macroscopic capillary model. Once the
material is saturated with water, extrusion takes place upon reduction of the
externally applied pressure; Our results for the extrusion pressure can only be
understood by assuming that the limiting extrusion mechanism is the nucleation
of a vapour bubble inside the pores. A comparison of calculated and
experimental nucleation pressures shows that a proper inclusion of line tension
effects is necessary to account for the observed values of nucleation barriers.
Negative line tensions of order are found for our
system, in reasonable agreement with other experimental estimates of this
quantity
Composition and reversibility of fouling on low-pressure membranes in the filtration of coagulated water: insights into organic fractions behaviour
The primary problem for the application of microfiltration (MF) and ultrafiltration (UF) membrane technology is membrane fouling. Such is the case that understanding membrane fouling has become one of the major factors driving MF and UF membrane technology for- ward. Nevertheless, identifying the constituents that most contribute to membrane fouling 20 and quantifying how they are detached when backwashing (BW) and cleaning-in-place (CIP) are applied still remains a challenging task. The aim of the present study was to quan- tify membrane fouling development during filtration and membrane fouling detachment during BW and CIP in terms of membrane permeability changes and masses of inorganic and organic constituents accumulated on the membrane. The study was conducted using 25 bench-scale MF and UF modules fed with coagulated and settled water coming from a drinking water treatment plant and operated under dead-end and cross-flow operation modes. The experiments consisted inconsecutive permeation (20 min) alternated with BW with permeate water (1.0 min) (periodically chemically assisted with NaClO and NaOH) and followed by a two-stage CIP consisting first in an oxidising and basic step (NaClO and 30 NaOH) and second in an acidic step (citric acid). Feed, permeate, retentate (when present) and cleaning discharge streams were monitored for turbidity, total and dissolved organic carbon (TOC and DOC, respectively), UV 254 and inorganic ions (Al, Fe, P). DOC was frac- tionated by high-performance size exclusion chromatography to gain insight into the beha- viour of the different organic fractions. Results showed that both MF and UF membranes 35 successfully removed turbidity, Al and Fe, whereas UV 254 was moderately removed and TOC and DOC poorly removed, with removal percentages higher for UF than for MF. With regard to the organic fractions, the largest molecular weight compounds were moderately removed while the smallest organic fractions seemed to totally permeate through both membranes. The results also showed that foulants were poorly washed out from thePeer ReviewedPostprint (author's final draft
Reversibility of fouling on ultrafiltration membrane by backwashing and chemical cleaning: differences in organic fractions behaviour
Membrane fouling is an inherent phenomenon in ultrafiltration (UF) membrane processes, making it necessary to periodically perform backwashes (BW) and chemical cleanings in place (CIP) to restore the initial permeability of the membrane. The objective of this study was (1) to explore systematically the effect of distinct BW-related variables (BW transmembrane pressure, duration, frequency and composition) on the reversibility of UF membrane fouling and on the permeate quality (in terms of total organic carbon, turbidity and UV absorbance) over successive filtration/BW cycles; and (2) to identify which organic fractions were most removed by the membrane and, of these, which were most detached after BW, alkaline and oxidant CIP and acid CIP episodes. For this purpose, a bench-scale outside-in hollow fibre module operated under dead-end filtration mode at constant transmembrane pressure and treating settled water from a drinking water treatment plant was employed. Dissolved organic carbon fractionation was performed by high-performance size-exclusion chromatography. Results showed that, in general, the more intensive the BW was (in terms of high transmembrane pressure, shortened frequency and prolonged duration) the more effective it was in removing fouling from the membrane. Concerning the composition of the water used for the BW, the addition of NaClO led to maximum fouling reversibility, closely followed by the combination of NaOH+NaClO, while citric acid and NaOH contributed little compared to water alone. However, results also showed that irreversible fouling was never completely avoided whatever the BW regime applied, leading to a gradual increase in the total resistance over time. Larger differences in the behaviour of the different organic fractions were observed. UF membrane preferentially retained the heaviest fraction of biopolymers (BP), while the intermediate fraction of humic substances (HS) was removed at a lower percentage and the lighter fractions seemed to entirely pass through the UF membrane. The successive application of BW and CIPs resulted in the detachment from the membrane of a significant percentage of the retained BP, whereas only a modest percentage of the retained HS.Peer ReviewedPostprint (author's final draft
Understanding the growth mechanism of BaZrS chalcogenide perovskite thin films from sulfurized oxide precursors
Barium zirconium sulfide (BaZrS) is an earth-abundant and environmentally
friendly chalcogenide perovskite with promising properties for various energy
conversion applications. Recently, sulfurization of oxide precursors has been
suggested as a viable solution for effective synthesis, especially from the
perspective of circumventing the difficulty of handling alkali earth metals. In
this work, we explore in detail the synthesis of BaZrS from Ba-Zr-O oxide
precursor films sulfurized at temperatures ranging from 700 C to 1000
C. We propose a formation mechanism of BaZrS based on a two-step
reaction involving an intermediate amorphization step of the BaZrO3 crystalline
phase. We show how the diffusion of sulfur (S) species in the film is the
rate-limiting step of this reaction. The processing temperature plays a key
role in determining the total fraction of conversion from oxide to sulfide
phase at a constant flow rate of the sulfur-containing H2S gas used as a
reactant. Finally, we observe the formation of stoichiometric BaZrS
(1:1:3), even under Zr-rich precursor conditions, with the formation of ZrO
as a secondary phase. This marks BaZrS quite unique among the other types
of chalcogenides, such as chalcopyrites and kesterites, which can instead
accommodate quite a large range of non-stoichiometric compositions. This work
opens up a pathway for further optimization of the BaZrS synthesis process,
straightening the route towards future applications of this material.Comment: Equal contributio
In Antisynthetase Syndrome, ACPA Are Associated With Severe and Erosive Arthritis: An Overlapping Rheumatoid Arthritis and Antisynthetase Syndrome
International audienceAbstract: Anticitrullinated peptide/protein antibodies (ACPA), which are highly specific for rheumatoid arthritis (RA), may be found in some patients with other systemic autoimmune diseases. The clinical significance of ACPA in patients with antisynthetase syndrome (ASS), a systemic disease characterized by the association of myositis, interstitial lung disease, polyarthralgia, and/or polyarthritis, has not yet been evaluated with regard to phenotype, prognosis, and response to treatment. ACPA-positive ASS patients were first identified among a French multicenter registry of patients with ASS. Additionally, all French rheumatology and internal medicine practitioners registered on the Club Rhumatismes et Inflammation web site were asked to report their observations of ASS patients with ACPA. The 17 collected patients were retrospectively studied using a standardized questionnaire and compared with 34 unselected ACPA-negative ASS patients in a case–control study. All ACPA-positive ASS patients suffered from arthritis versus 41% in the control group (P 7-year mean follow-up, extra-articular outcomes and survival were not different. ACPA-positive ASS patients showed an overlapping RA–ASS syndrome, were at high risk of refractory erosive arthritis, and might experience ASS flare when treated with antitumor necrosis factor drugs. In contrast, other biologics such as anti-CD20 mAb were effective in this context, without worsening systemic involvements
Expected Performance of the ATLAS Experiment - Detector, Trigger and Physics
A detailed study is presented of the expected performance of the ATLAS
detector. The reconstruction of tracks, leptons, photons, missing energy and
jets is investigated, together with the performance of b-tagging and the
trigger. The physics potential for a variety of interesting physics processes,
within the Standard Model and beyond, is examined. The study comprises a series
of notes based on simulations of the detector and physics processes, with
particular emphasis given to the data expected from the first years of
operation of the LHC at CERN
Identifying the cognitive predictors of early counting and calculation skills: Evidence from a longitudinal study.
The extent that phonological, visual-spatial STM and non-symbolic quantitative skills support the development of counting and calculation skills was examined in this 14-month longitudinal study of 125 children. Initial assessments were made when the children were 4:8. Phonological awareness, visual-spatial STM and non-symbolic approximate discrimination predicted growth in early calculation skills. These results suggest that both the approximate number system and domain-general phonological and visual-spatial skills support early calculation. In contrast, only performance on a small non-symbolic quantity discrimination task (where the presented quantities were always within the subitising range) predicted growth in cardinal counting skills. These results suggest that the development of counting and calculation are supported by different cognitive abilities
Electrically evoked compound action potentials are different depending on the site of cochlear stimulation.
One of the many parameters that can affect cochlear implant (CI) users' performance is the site of presentation of electrical stimulation, from the CI, to the auditory nerve. Evoked compound action potential (ECAP) measurements are commonly used to verify nerve function by stimulating one electrode contact in the cochlea and recording the resulting action potentials on the other contacts of the electrode array. The present study aimed to determine if the ECAP amplitude differs between the apical, middle, and basal region of the cochlea, if double peak potentials were more likely in the apex than the basal region of the cochlea, and if there were differences in the ECAP threshold and recovery function across the cochlea. ECAP measurements were performed in the apical, middle, and basal region of the cochlea at fixed sites of stimulation with varying recording electrodes. One hundred and forty one adult subjects with severe to profound sensorineural hearing loss fitted with a Standard or FLEX(SOFT) electrode were included in this study. ECAP responses were captured using MAESTRO System Software (MED-EL). The ECAP amplitude, threshold, and slope were determined using amplitude growth sequences. The 50% recovery rate was assessed using independent single sequences that have two stimulation pulses (a masker and a probe pulse) separated by a variable inter-pulse interval. For all recordings, ECAP peaks were annotated semi-automatically. ECAP amplitudes were greater upon stimulation of the apical region compared to the basal region of the cochlea. ECAP slopes were steeper in the apical region compared to the basal region of the cochlea and ECAP thresholds were lower in the middle region compared to the basal region of the cochlea. The incidence of double peaks was greater upon stimulation of the apical region compared to the basal region of the cochlea. This data indicates that the site and intensity of cochlear stimulation affect ECAP properties
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