Lunar regolith as a feedstock for selective laser melting

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Functionalizing surfaces of 3D printed objects with an integrated low-cost atmospheric pressure micro plasma torch

Polymer 3D printing via the Fused Filament Fabrication (FFF) technology is a now well-known process designed to build three-dimensional objects from computer-aided-design (CAD) models in a layer-by-layer method. First dedicated for prototyping, this technology is now widely spread on the additive manufacturing (AM) and production market. With the decreasing costs of the equipment and materials needed as well as the growing simplicity of use and reliability of the technique, one can now have a 3D printer for the same cost and as user-friendly as a regular desktop inkjet printer. Among the commercially distributed thermoplastics, polylactic acid (PLA) and acrylonitrile butadiene styrene (ABS) are the two most outspread but one can also find acrylonitrile styrene acrylate (ASA), polyethylene terephthalate (PET) polycarbonate (PA) and much more. When assuming that single material 3D printed objects are obtained from growing layers in the (xy) plane stacked along the z axis, they are known to show really good tensile strength in the x and y direction but much less in the z direction due to insufficient interlayer bounding. Bigger problems arise when trying to print a multi-material object. Indeed, the chemical incompatibility of the different printed materials as well as their different thermal expansion coefficients are from the materials properties that can cause a very weak diffusion bonding at the interface. Authors started recently to focus on this problematic and very few studies can be found on the subject. To overcome the problem, we consider here improving the wettability of the printed polymer at the interface layer as it cause the extruded material to better spread over this layer, hence increasing the diffusion bonding. This work aims to investigate the effect of an atmospheric cold plasma treatment on the wettability and bonding of 3D printed objects. For this task, we designed an atmospheric pressure dielectric barrier discharge (DBD) plasma torch integrated on a commercial 3D printer. Thus, the device can be controlled to apply a plasma treatment while printing an object. As the deposition process will need to be done on complex surfaces and on thermal sensitive materials, a new type of high voltage nano-pulse generator had to be developed for this device. It gives the possibility to generate a homogeneous plasma (with less filament discharge) in a very small volume and a relatively extended plasma plume with a limitation of the gas temperature. Wettability measurements and tensile tests were carried out on 3D printed + plasma treated objects, obtained with our newly designed device. The material bonding is evaluated either within a single-material specimen by applying the treatment at the interlayers or within a multi-material one by treating only the interface layer of the two different materials.

Interaction of (3-Aminopropyl)triethoxysilane With Late Ar-N 2 Afterglow: Application to Nanoparticles Synthesis

International audienceFrom results of in situ FTIR absorption and optical emission spectroscopy, the interaction of (3‐aminopropyl)triethoxysilane (APTES) with late Ar-N2 afterglow is shown to occur mainly with N atoms. They react preferentially with carbon from CHx groups in the precursor, leading to the synthesis of CN bonds. No production of NH radical is observed, demonstrating the lack of direct reaction between active nitrogen and APTES. The -NH2 group is not affected by the afterglow. One of the C-C bonds of the propylamine group in the APTES is likely broken. These nanoparticles present secondary amides due to reactions with active nitrogen. They are amorphous and react in air to produce a salt

Herschel Observations of Disks around Late-type Stars

A set of twenty late-type (K5-M5) stars were observed with the Herschel Space Observatory at 100 and 160 microns with the goal of searching for far-infrared excesses indicative of the presence of circumstellar disks. Out of this sample, four stars (TYC 7443-1102-1, TYC 9340-437-1, GJ 784 and GJ 707) have infrared excesses above their stellar photospheres at either 100 or 160 μm or both. At 100 microns TYC 9340-437-1 is spatially resolved with a shape that suggests it is surrounded by a face-on disk. The 100 μm excess flux associated with GJ 707 is marginal at around 3σ. The excess flux associated with GJ 784 is most likely due to a background galaxy as the dust radius estimated from the spectral energy fit implies that any associated dust disk should have been resolved in the Herschel images but is not. TYC 7443-1102-1 has been observed with ALMA which resolves the emission at its location into two distinct sources making the Herschel excess most likely also due to a background galaxy. It is worth noting that this star is in the 23 Myr old β Pic association. With a disk luminosity on the order of 10⁻³ L_*, this system is an ideal follow-up target for high-contrast imaging and ALMA

Diagnostic accuracy of C-reactive protein and procalcitonin in suspected community-acquired pneumonia adults visiting emergency department and having a systematic thoracic CT scan

ESCAPED Study GroupInternational audienceIntroductionCommunity-acquired pneumonia (CAP) requires prompt treatment, but its diagnosis is complex. Improvement of bacterial CAP diagnosis by biomarkers has been evaluated using chest X-ray infiltrate as the CAP gold standard, producing conflicting results. We analyzed the diagnostic accuracy of biomarkers in suspected CAP adults visiting emergency departments for whom CAP diagnosis was established by an adjudication committee which founded its judgment on a systematic multidetector thoracic CT scan.MethodsIn an ancillary study of a multi-center prospective study evaluating the impact of systematic thoracic CT scan on CAP diagnosis, sensitivity and specificity of C-reactive protein (CRP) and procalcitonin (PCT) were evaluated. Systematic nasopharyngeal multiplex respiratory virus PCR was performed at inclusion. An adjudication committee classified CAP diagnostic probability on a 4-level Likert scale, based on all available data.ResultsTwo hundred patients with suspected CAP were analyzed. The adjudication committee classified 98 patients (49.0 %) as definite CAP, 8 (4.0 %) as probable, 23 (11.5 %) as possible and excluded in 71 (35.5 %, including 29 patients with pulmonary infiltrates on chest X-ray). Among patients with radiological pulmonary infiltrate, 23 % were finally classified as excluded. Viruses were identified by PCR in 29 % of patients classified as definite. Area under the curve was 0.787 [95 % confidence interval (95 % CI), 0.717 to 0.857] for CRP and 0.655 (95 % CI, 0.570 to 0.739) for PCT to detect definite CAP. CRP threshold at 50 mg/L resulted in a positive predictive value of 0.76 and a negative predictive value of 0.75. No PCT cut-off resulted in satisfactory positive or negative predictive values. CRP and PCT accuracy was not improved by exclusion of the 25 (25.5 %) definite viral CAP cases.ConclusionsFor patients with suspected CAP visiting emergency departments, diagnostic accuracy of CRP and PCT are insufficient to confirm the CAP diagnosis established using a gold standard that includes thoracic CT scan. Diagnostic accuracy of these biomarkers is also insufficient to distinguish bacterial CAP from viral CAP

Atmospheric Aerosol Assisted Pulsed Plasma Polymerization: An Environmentally Friendly Technique for Tunable Catechol-Bearing Thin Films

In this work, an atmospheric aerosol assisted pulsed plasma process is reported as an environmentally friendly technique for the preparation of tunable catechol-bearing thin films under solvent and catalyst free conditions. The approach relies on the direct injection of dopamine acrylamide dissolved in 2-hydroxyethylmethacrylate as comonomer into the plasma zone. By adjusting the pulsing of the electrical discharge, the reactive plasma process can be alternatively switch ON (tON) and OFF (tOFF) during different periods of time, thus allowing a facile and fine tuning of the catechol density, morphology and deposition rate of the coating. An optimal tON/tOFF ratio is established, that permits maximizing the catechol content in the deposited film. Finally, a diagram, based on the average energy input into the process, is proposed allowing for easy custom synthesis of layers with specific chemical and physical properties, thus highlighting the utility of the developed dry plasma route

Herschel observations of disks around late-type stars

A set of twenty late-type (K5-M5) stars were observed with the Herschel Space Observatory at 100 and 160 microns with the goal of searching for far-infrared excesses indicative of the presence of circumstellar disks. Out of this sample, four stars (TYC 7443-1102-1, TYC 9340-437-1, GJ 784 and GJ 707) have infrared excesses above their stellar photospheres at either 100 or 160 μm or both. At 100 microns TYC 9340-437-1 is spatially resolved with a shape that suggests it is surrounded by a face-on disk. The 100 μm excess flux associated with GJ 707 is marginal at around 3σ. The excess flux associated with GJ 784 is most likely due to a background galaxy as the dust radius estimated from the spectral energy fit implies that any associated dust disk should have been resolved in the Herschel images but is not. TYC 7443-1102-1 has been observed with ALMA which resolves the emission at its location into two distinct sources making the Herschel excess most likely also due to a background galaxy. It is worth noting that this star is in the 23 Myr old β Pic association. With a disk luminosity on the order of 10-3 L*, this system is an ideal follow-up target for high-contrast imaging and ALMA

Direct Imaging of the HD 35841 Debris Disk: a Polarized Dust Ring from Gemini Planet Imager and an Outer Halo From \u3ci\u3eHST/\u3c/i\u3eSTIS

We present new high resolution imaging of a light-scattering dust ring and halo around the young star HD 35841. Using spectroscopic and polarimetric data from the Gemini Planet Imager in H-band (1.6 μm), we detect the highly inclined (i = 85°) ring of debris down to a projected separation of ∼12 au (∼0.″12) for the first time. Optical imaging from HST/STIS shows a smooth dust halo extending outward from the ring to \u3e140 au (\u3e1.″4). We measure the ring\u27s scattering phase function and polarization fraction over scattering angles of 22°-125°, showing a preference for forward scattering and a polarization fraction that peaks at ∼30% near the ansae. Modeling of the scattered-light disk indicates that the ring spans radii of ∼60-220 au, has a vertical thickness similar to that of other resolved dust rings, and contains grains as small as 1.5 μm in diameter. These models also suggest the grains have a low porosity, are more likely to consist of carbon than astrosilicates, and contain significant water ice. The halo has a surface brightness profile consistent with that expected from grains pushed by radiation pressure from the main ring onto highly eccentric but still bound orbits. We also briefly investigate arrangements of a possible inner disk component implied by our spectral energy distribution models, and speculate about the limitations of Mie theory for doing detailed analyses of debris disk dust populations

European and multi-ancestry genome-wide association meta-analysis of atopic dermatitis highlights importance of systemic immune regulation

Atopic dermatitis (AD) is a common inflammatory skin condition and prior genome-wide association studies (GWAS) have identified 71 associated loci. In the current study we conducted the largest AD GWAS to date (discovery N = 1,086,394, replication N = 3,604,027), combining previously reported cohorts with additional available data. We identified 81 loci (29 novel) in the European-only analysis (which all replicated in a separate European analysis) and 10 additional loci in the multi-ancestry analysis (3 novel). Eight variants from the multi-ancestry analysis replicated in at least one of the populations tested (European, Latino or African), while two may be specific to individuals of Japanese ancestry. AD loci showed enrichment for DNAse I hypersensitivity and eQTL associations in blood. At each locus we prioritised candidate genes by integrating multi-omic data. The implicated genes are predominantly in immune pathways of relevance to atopic inflammation and some offer drug repurposing opportunities.</p