Mécanismes d'action des “Polymer Processing Aids” (PPA) dans l'élimination du défaut de peau de requin en extrusion

National audienceDepuis plus de vingt ans, des “Polymer Processing Aids” (PPA) fluorés sont utilisés industriellement pour éliminer les défauts de peau de requin en extrusion. L'objectif de ce travail est de comprendre les mécanismes d'action de ces PPA. L'influence des PPA sur la pression en filière et sur l'aspect des extrudats est d'abord étudiée, montrant simultanément une chute de pression et une élimination progressive du défaut. La formation d'un dépôt en filière est ensuite analysée par microscopie électronique à balayage (MEB). On constate l'existence d'un dépôt hétérogène de fluoropolymère, sous forme de lignes parallèles à l'écoulement, qui apparaît en deux temps. Enfin, l'évolution des profils de vitesse permet de corréler la chute de pression en filière à l'apparition de glissement à la paroi, ainsi que le glissement obtenu à la densité de dépôt

Influence of the nature of fluoropolymer processing aids on the elimination of sharkskin defect in LLDPE extrusion

International audienceFluoropolymer-based processing aids (PPA) are commonly used to suppress sharkskin defects in polyolefin extrusion. PPA's also lead to a decrease in die pressure and a slight increase in flow rate by coating die walls and inducing wall slip. The aim of this work is to investigate the influence of different types of PPAs on the physical parameters in the die at various scales. We used a modular slit die fed by an extruder to measure die pressure and velocity profiles by Laser Doppler Velocimetry (LDV), and to characterize die surface coating by Scanning Electronic Microscopy (SEM)

Assessing the potential outcomes of achieving the World Health Organization global non-communicable diseases targets for risk factors by 2025: is there also an economic dividend?

International audienceOBJECTIVES:This study assesses the change in premature mortality and in morbidity under the scenario of meeting the World Health Organization (WHO) global targets for non-communicable disease (NCD) risk factors (RFs) by 2025 in France. It also estimates medical expenditure savings because of the reduction of NCD burden.STUDY DESIGN:A microsimulation model is used to predict the future health and economic outcomes in France.METHODS:A 'RF targets' scenario, assuming the achievement of the six targets on RFs by 2025, is compared to a counterfactual scenario with respect to disability-adjusted life years and healthcare costs differences.RESULTS:The achievement of the RFs targets by 2025 would save about 25,300 (and 75,500) life years in good health in the population aged 25-64 (respectively 65+) years on average every year and would help to reduce healthcare costs by about €660 million on average per year, which represents 0.35% of the current annual healthcare spending in France. Such a reduction in RFs (net of the natural decreasing trend in mortality) would contribute to achieving about half of the 2030 NCD premature mortality target in France.CONCLUSIONS:The achievement of the RF targets would lead France to save life years and life years in good health in both working-age and retired people and would modestly reduce healthcare expenditures. To achieve RFs targets and to curb the growing burden of NCDs, France has to strengthen existing and implement new policy interventions

Potential of Sentinel-2 satellite images to monitor vine fields grown at a territorial scale

Aim: The aim of this short note is to provide first insights into the ability of Sentinel-2 images to monitor vine growth across a whole season. It focuses on verifying the practical temporal resolution that can be reached with Sentinel-2 images, the main stages of Mediterranean vineyard development as well as potential relevant agronomic information that can be seen on the temporal vegetation curves arising from Sentinel-2 images. Methods and results: The study was carried out in 2017 in a production vineyard located in southern France, 2 km from the Mediterranean seashore. Sentinel-2 images acquired during the whole vine growing cycle were considered, i.e. between the 3rd of March 2017 and the 10th of October 2017. The images were used to compute the classical normalized difference vegetation index (NDVI). Time series of NDVI values were analyzed on four blocks chosen for exhibiting different features, e.g. age, missing plants, weeding practices. The practical time lag between two usable images was closer to 16 days than to the 10 theoretical days (with only one satellite available at the date of the experiment), i.e. near 60% of the theoretical one. Results show that it might be possible to identify i) the main steps of vine development (e.g. budburst, growth, trimming, growth stop and senescence), ii) weed management and inter-row management practices, and iii) possible reasons for significant inter-block differences in vegetative expression (e.g. young vines that have recently been planted, low-productive blocks affected by many missing vines). Conclusions: Although this experiment was conducted at a time when Sentinel-2b was not fully operational, results showed that a sufficient number of usable images was available to monitor vine development. The availability of two Sentinel satellites (2a and 2b) in upcoming seasons should increase the number of usable images and the temporal resolution of the time series. This study also showed the limitations of the Sentinel-2 images’ resolution to provide within-block information in the case of small blocks or blocks with complex borders or both. Significance and impact of the study: This technical note demonstrated the potential of Sentinel-2 images to characterize vineyard blocks’ vigor and to monitor winegrowers’ practices at a territorial (regional) scale. The impact of management operations such as weeding and trimming, along with their incidence on canopy size, were observed on the NDVI time series. Some relevant parameters (slope, maximum values) may be derived from the NDVI time series, providing new insights into the monitoring of vineyards at a large scale. These results provided areas for further investigation, especially regarding the development of new indicators to characterize block-climate relationships

Search for heavy neutral lepton production in K+ decays

A search for heavy neutral lepton production in K + decays using a data sample collected with a minimum bias trigger by the NA62 experiment at CERN in 2015 is reported. Upper limits at the 10−7 to 10−6 level are established on the elements of the extended neutrino mixing matrix |Ue4| 2 and |Uμ4| 2 for heavy neutral lepton mass in the ranges 170–448 MeV/c2 and 250–373 MeV/c2, respectively. This improves on the previous limits from HNL production searches over the whole mass range considered for |Ue4|2 and above 300 MeV/c2 for |Uμ4|2

Pros and cons of different therapeutic antibody formats for recombinant antivenom development.

Antibody technologies are being increasingly applied in the field of toxinology. Fuelled by the many advances in immunology, synthetic biology, and antibody research, different approaches and antibody formats are being investigated for the ability to neutralize animal toxins. These different molecular formats each have their own therapeutic characteristics. In this review, we provide an overview of the advances made in the development of toxin-targeting antibodies, and discuss the benefits and drawbacks of different antibody formats in relation to their ability to neutralize toxins, pharmacokinetic features, propensity to cause adverse reactions, formulation, and expression for research and development (R&D) purposes and large-scale manufacturing. A research trend seems to be emerging towards the use of human antibody formats as well as camelid heavy-domain antibody fragments due to their compatibility with the human immune system, beneficial therapeutic properties, and the ability to manufacture these molecules cost-effectively

On the mechanisms governing gas penetration into a tokamak plasma during a massive gas injection

A new 1D radial fluid code, IMAGINE, is used to simulate the penetration of gas into a tokamak plasma during a massive gas injection (MGI). The main result is that the gas is in general strongly braked as it reaches the plasma, due to mechanisms related to charge exchange and (to a smaller extent) recombination. As a result, only a fraction of the gas penetrates into the plasma. Also, a shock wave is created in the gas which propagates away from the plasma, braking and compressing the incoming gas. Simulation results are quantitatively consistent, at least in terms of orders of magnitude, with experimental data for a D 2 MGI into a JET Ohmic plasma. Simulations of MGI into the background plasma surrounding a runaway electron beam show that if the background electron density is too high, the gas may not penetrate, suggesting a possible explanation for the recent results of Reux et al in JET (2015 Nucl. Fusion 55 093013)

Alignment of the ALICE Inner Tracking System with cosmic-ray tracks

37 pages, 15 figures, revised version, accepted by JINSTALICE (A Large Ion Collider Experiment) is the LHC (Large Hadron Collider) experiment devoted to investigating the strongly interacting matter created in nucleus-nucleus collisions at the LHC energies. The ALICE ITS, Inner Tracking System, consists of six cylindrical layers of silicon detectors with three different technologies; in the outward direction: two layers of pixel detectors, two layers each of drift, and strip detectors. The number of parameters to be determined in the spatial alignment of the 2198 sensor modules of the ITS is about 13,000. The target alignment precision is well below 10 micron in some cases (pixels). The sources of alignment information include survey measurements, and the reconstructed tracks from cosmic rays and from proton-proton collisions. The main track-based alignment method uses the Millepede global approach. An iterative local method was developed and used as well. We present the results obtained for the ITS alignment using about 10^5 charged tracks from cosmic rays that have been collected during summer 2008, with the ALICE solenoidal magnet switched off.Peer reviewe

Modelling of the effect of ELMs on fuel retention at the bulk W divertor of JET

Effect of ELMs on fuel retention at the bulk W target of JET ITER-Like Wall was studied with multi-scale calculations. Plasma input parameters were taken from ELMy H-mode plasma experiment. The energetic intra-ELM fuel particles get implanted and create near-surface defects up to depths of few tens of nm, which act as the main fuel trapping sites during ELMs. Clustering of implantation-induced vacancies were found to take place. The incoming flux of inter-ELM plasma particles increases the different filling levels of trapped fuel in defects. The temperature increase of the W target during the pulse increases the fuel detrapping rate. The inter-ELM fuel particle flux refills the partially emptied trapping sites and fills new sites. This leads to a competing effect on the retention and release rates of the implanted particles. At high temperatures the main retention appeared in larger vacancy clusters due to increased clustering rate