Homogenization of Inconel 718 Made by Additive Manufacturing and Suction Casting

Inconel 718 is considered a promising candidate for production via additive manufacturing (AM) due to its excellent weldability. However, compared to traditional manufacturing methods, less attention has been paid to developing heat treatments of AM components. To better design the post-processing of Inconel 718 made by AM techniques, the CALPHAD (Calculation of Phase Diagrams) method is applied to study the phase equilibrium, metastable phase behavior, and phase transformations during the homogenization process of Inconel 718. Scanning electron microscopy, energy dispersive X-ray spectroscopy, and electron backscatter diffraction are employed to study the microstructure evolution of different samples supporting the CALPHAD model prediction. Suction cast samples are also investigated to provide a benchmark for comparison. The calculations and experiments are in agreement that homogenization occurs more rapidly in samples made by laser-powder bed fusion than by suction casting. Intriguingly, significant grain growth occurs at the homogenization temperature of 1,180°C for the suction cast samples, but only recrystallization and minor grain growth occurs for the AM samples. AM Inconel 718 samples show promise for reducing the time required for homogenization heat treatment. It is observed that the detrimental Laves phase dissolves in AM samples within 20 minutes due to the smaller grain size and less pronounced Nb segregation than suction cast samples. The new findings confirm that post-processing optimization for AM Inconel 718 components are essential

Xanthomonas albilineans is able to move outside of the sugarcane xylem despite its reduced genome and the absence of a Hrp type III secretion system.

Xanthomonas albilineans, the causal agent of leaf scald disease of sugarcane, is a pathogen that experienced genome reduction during its speciation. Additionally, this xanthomonad is notably missing the Hrp type III secretion system and the xanthan gene cluster that are commonly found in pathogenic Xanthomonas species. X. albilineans was up to now considered as limited to the xylem of sugarcane. However, recently published studies suggested that X. albilineans was able to invade tissues other than the xylem of sugarcane leaves but the occurrence of X. albilineans outside the xylem has not been clearly proven. In this study, we used confocal microscopy and transmission electron microscopy to investigate the localization of this pathogen in diseased leaves and stalks of sugarcane. Three sugarcane cultivars with different levels of resistance to leaf scald were inoculated with the green fluorescent protein labelled X. albilineans strains XaFL07-1 (from Florida) and GPE PC73 (from Guadeloupe). Sections of sugarcane leaves and stalks were examined 8-60 days after inoculation in order to localize X. albilineans in the different plant tissues. Confocal microscopy observation of symptomatic leaves confirmed the presence of the pathogen in the protoxylem and the metaxylem, however, X. albilineans was also observed in the phloem, the parenchyma and the bulliform cells of the leaves. Similarly, the protoxylem and the metaxylem of infected sugarcane stalks were invaded by X. albilineans. Surprisingly, the pathogen was also observed in apparently intact storage cells of the stalk and in the intercellular spaces between these cells. Several of these observations made by confocal microscopy have been confirmed by transmission electron microscopy. X. albilineans can therefore no longer be considered as a xylem-limited pathogen. To our knowledge, this is the first description of a plant pathogenic bacterium invading apparently intact non-vascular plant tissue and multiplying in parenchyma cells. The mechanisms and virulence factors used by X. albilineans to enter and invade different tissues of sugarcane remain to be identified. (Résumé d'auteur

Getting scaling into research : considering the four guiding principles throughout the research process

French and Spanish versions available in IDRC Digital LibraryThis one-pager aims to focus new researchers on the processes and questions that will impact findings and outcomes of their research: “While doing research, researchers might ask: What evidence is needed to determine optimal scale? How will we involve stakeholders in data collection, analysis/synthesis, and interpretation? What key moments can we foresee for learning and adaptation?” A link is provided to scaling science: https://www.idrc.ca/en/research-in-action/scaling-science

How i do it: Lung ultrasound

In the last 15 years, a new imaging application of sonography has emerged in the clinical arena: lung ultrasound (LUS). From its traditional assessment of pleural effusions and masses, LUS has moved towards the revolutionary approach of imaging the pulmonary parenchyma, mainly as a point-of-care technique. Although limited by the presence of air, LUS has proved to be useful in the evaluation of many different acute and chronic conditions, from cardiogenic pulmonary edema to acute lung injury, from pneumothorax to pneumonia, from interstitial lung disease to pulmonary infarctions and contusions. It is especially valuable since it is a relatively easy-to-learn application of ultrasound, less technically demanding than other sonographic examinations. It is quick to perform, portable, repeatable, non-ionizing, independent from specific acoustic windows, and therefore suitable for a meaningful evaluation in many different settings, both inpatient and outpatient, in both acute and chronic conditions.In the next few years, point-of-care LUS is likely to become increasingly important in many different clinical settings, from the emergency department to the intensive care unit, from cardiology to pulmonology and nephrology wards. © 2014 Gargani and Volpicelli; licensee BioMed Central Ltd

Experimental Investigation of Gully Formation Under Low Pressure and Low Temperature Conditions

International audienceIntroduction: A large morphological diversity of gullies is observed on Earth and on Mars. Debris flow – a non-newtonian flow comprising a sediment-water mix – is a common process attributed to gully formation on both planets [1, 2]. Many variables can influence the morphology of debris flows (grainsizes, discharge , slope, soil moisture, etc) and their respective influences are difficult to disentangle in the field. Furthermore effects specific to the martian environment have not yet been explored in detail. Some preliminary laboratory simulations have already been performed that isolate some of these variables. Cold room experiments [3] were already perfomed to test the effect of a melted surface layer on the formation of linear gullies over sand dunes. Low pressure experiments [4] were performed to test the effect of the atmospheric pressure on erosional capacity and runout distance of the flows. Our aim is to develop a new set of experiments both under Martian atmospheric pressure and terrestrial atmospheric pressure in order to reproduce the variability of the observed morphologies under well constrained experimental conditions