21,054 research outputs found
Moving forward in the Euro-Mediterranean research and innovation partnership : the experience of the MIRA project
Cet article analyse le cadre politique Euro-Med qui affecte les coopérations en matière de recherche depuis la déclaration de Barcelone jusqu'à la politique de voisinage. Nous examinons les orientations de politique et ses changements, les effets qu’ils ont sur les collaborations scientiiques en termes de publications et de gouvernance de la recherche en utilisant les données de l'enquête MIRA sur les collaborations scientiiques. Nous comparons aussi les programmes inancés par l’Europe et ceux inancés par les coopérations bilatérales. Enin nous identiions des propositions pour générer des partenariats cofinancés et co-décidés
Changes in Subcellular Localization of Host Proteins Induced by Plant Viruses
Viruses are dependent on host factors at all parts of the infection cycle, such as translation, genome replication, encapsidation, and cell-to-cell and systemic movement. RNA viruses replicate their genome in compartments associated with the endoplasmic reticulum, chloroplasts, and mitochondria or peroxisome membranes. In contrast, DNA viruses replicate in the nucleus. Viral infection causes changes in plant gene expression and in the subcellular localization of some host proteins. These changes may support or inhibit virus accumulation and spread. Here, we review host proteins that change their subcellular localization in the presence of a plant virus. The most frequent change is the movement of host cytoplasmic proteins into the sites of virus replication through interactions with viral proteins, and the protein contributes to essential viral processes. In contrast, only a small number of studies document changes in the subcellular localization of proteins with antiviral activity. Understanding the changes in the subcellular localization of host proteins during plant virus infection provides novel insights into the mechanisms of plant–virus interactions and may help the identification of targets for designing genetic resistance to plant viruses
Mechanical pretreatment of waste paper for biogas production
In the anaerobic digestion of lignocellulosic materials such as waste paper, the accessibility of microorganisms to the fermentable sugars is restricted by their complex structure. A mechanical pretreatment with a Hollander beater was assessed in order to reduce the biomass particle size and to increase the feedstock’ specific surface area available to the microorganisms, and therefore improve the biogas yield. Pretreatment of paper waste for 60 min improves the methane yield by 21%, from a value of 210 ml/gVS corresponding to untreated paper waste to 254 ml/gVS. 30 min pretreatment have no significant effect on the methane yield. A response surface methodology was used to evaluate the effect of the beating time and feedstock/inoculum ratio on the methane yield. An optimum methane yield of 253 ml/gVS was achieved at 55 min of beating pretreatment and a F/I ratio of 0.3
On the rapid manufacturing process of functional 3D printed sand molds
3D printing sand mold technology offers an opportunity for the foundry industry to rethink old casting approaches and to revive the manufacturing approach using computer models. One of the major concerns in sand molding using 3D printing is the functional characterization of the 3D printed molds as its mechanical and mass transport properties. This research paper discusses the effects of binder content on the mechanical strength and the permeability of 3DP sand molds at different curing conditions. The local permeability of the 3DP specimen was measured as a function of the injection flow rate in order to quantify the inertial pressure effects. The mechanical strength of the 3DP sand molds was characterized using traditional three-point bending strength measurements. The results show that the mechanical strength of the printed molds is deeply dependent on the amount of binder and the curing process. The 3PB strength was found to increase when cured at 100 °C and decrease when cured at 200 °C for all binder contents. The 3PB strength attains its maximum when cured at 100 °C for 2 h for all binder content. In contrast, no significant effect of the amount of binder on the initial permeability of the samples before curing was observed within the functional range of binder mass fraction (1.02–1.98 %). Maximum permeability is attained at the same conditions as the 3PB strength. Therefore, the mechanical strength of the sample can be optimized within the investigated range of binder contents without resulting in any significant decrease in permeability
The effect of ageing process on three-point bending strength and permeability of 3D printed sand molds
The objective of this paper was to investigate the effects of curing parameters (i.e., temperature and time), on the permeability and mechanical strength of the printed molds. Several sets of samples were hence produced with a state-of-the-art 3D printer using well-characterized silica sand and furan resin binder. Then, experiments were performed in which the evolution over time of the three-point bending (3 PB) strength and permeability of the samples were monitored at three different curing temperatures. From these measurements, both the individual and combined effects of curing temperature and time on the functionality of the 3D printed molds were assessed. Moreover, loss-on-ignition (LOI) tests were also performed in order to relate the loss of binder mass to the variation in permeability and mechanical strength of the samples. The results showed that the printed molds can be stored at room temperature for a long time before being used, roughly preserving the initial properties. No significant change in 3 PB strength was observed when curing at 100 °C. In contrast, the permeability was shown to decrease with increasing curing temperature
Determining the structure of Ru(0001) from low-energy electron diffraction of a single terrace
While a perfect hcp (0001) surface has three-fold symmetry, the diffraction
patterns commonly obtained are six-fold symmetric. This apparent change in
symmetry occurs because on a stepped surface, the atomic layers on adjacent
terraces are rotated by 180 degrees. Here we use a Low-Energy Electron
Microscope to acquire the three-fold diffraction pattern from a single hcp Ru
terrace and measure the intensity-vs-energy curves for several diffracted
beams. By means of multiple scattering calculations fitted to the experimental
data with a Pendry R-factor of 0.077, we find that the surface is contracted by
3.5(+-0.9) at 456 K.Comment: 10 pages, 4 figures. Corrected some typos, added more details.
Accepted for publication in Surface Science (Letters
Collagen-containing scaffolds enhance attachment and proliferation of non-cultured bone marrow multipotential stromal cells
Large bone defects are ideally treated with autografts, which have many limitations. Therefore, osteoconductive scaffolds loaded with autologous bone marrow (BM) aspirate are increasingly used as alternatives. The purpose of this study was to compare the growth of multipotential stromal cells (MSCs) from unprocessed BM on a collagen-containing bovine bone scaffold (Orthoss® Collagen) with a non-collagen-containing bovine bone scaffold, Orthoss®. Another collagen-containing synthetic scaffold, Vitoss® was included in the comparison. Colonization of scaffolds by BM MSCs (n = 23 donors) was evaluated using microscopy, colony forming unit-fibroblast assay and flow-cytometry. The number of BM MSCs initially attached to Orthoss® Collagen and Vitoss® was similar but greater than Orthoss® (p = 0.001 and p = 0.041, respectively). Furthermore, the number of MSCs released from Orthoss® Collagen and Vitoss® after 2-week culture was also higher compared to Orthoss® (p = 0.010 and p = 0.023, respectively). Interestingly, collagen-containing scaffolds accommodated larger numbers of lymphocytic and myelomonocytic cells. Additionally, the proliferation of culture-expanded MSCs on Orthoss® collagen and Vitoss® was greater compared to Orthoss® (p = 0.047 and p = 0.004, respectively). Collectively, collagen-containing scaffolds were superior in supporting the attachment and proliferation of MSCs when they were loaded with unprocessed BM aspirates. This highlights the benefit of collagen incorporation into bone scaffolds for use with autologous bone marrow aspirates as autograft substitutes
No X-Rays or Radio from the Nearest Black Holes and Implications for Future Searches
Astrometry from the Gaia mission was recently used to discover the two
nearest known stellar-mass black holes (BHs), Gaia BH1 and Gaia BH2. Both
systems contain stars in wide orbits (1.4 AU,
4.96 AU) around BHs. These objects are among the first
stellar-mass BHs not discovered via X-rays or gravitational waves. The
companion stars -- a solar-type main sequence star in Gaia BH1 and a
low-luminosity red giant in Gaia BH2 -- are well within their Roche lobes.
However, the BHs are still expected to accrete stellar winds, leading to
potentially detectable X-ray or radio emission. Here, we report observations of
both systems with the Chandra X-ray Observatory and radio observations with the
Very Large Array (for Gaia BH1) and MeerKAT (for Gaia BH2). We did not detect
either system, leading to X-ray upper limits of and and radio upper limits of and
. For Gaia BH2, the non-detection implies
that the the accretion rate near the horizon is much lower than the Bondi rate,
consistent with recent models for hot accretion flows. We discuss implications
of these non-detections for broader BH searches, concluding that it is unlikely
that isolated BHs will be detected via ISM accretion in the near future. We
also calculate evolutionary models for the binaries' future evolution using
Modules for Experiments in Stellar Astrophysics (MESA). We find that Gaia BH1
will be X-ray bright for 5--50 Myr when the star is a red giant, including 5
Myr of stable Roche lobe overflow. Since no symbiotic BH X-ray binaries are
known, this implies either that fewer than Gaia BH1-like binaries
exist in the Milky Way, or that they are common but have evaded detection,
perhaps due to very long outburst recurrence timescales.Comment: Submitted to PAS
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