Search

International audience; The combination of electronic and nuclear energy deposition may have a significant effect on the defect production and evolution. In nuclear reactor, the nuclear fuel is exposed to the irradiation of several particles such as the fission fragments (FF). Along their path, the ratio of electronic to nuclear energy loss evolves. To understand the impact of this coupling on the fuel microstructure, single and dual-beam ion irradiations of uranium dioxide (UO2) were carried out. The damage evolution was investigated by Raman spectroscopy analysis correlated with Transmission Electronic Microscopy observations. A significant effect of electronic energy dissipation on defect formation and evolution was found, depending on the electronic energy loss level. With the increase of electronic energy loss, the microstructure evolution is even more pronounced.

In this paper, we aim at developing new methods to join machine learning techniques and macroscopic differential models for vehicular traffic estimation and forecast. It is well known that data-driven and model-driven approaches have (sometimes complementary) advantages and drawbacks. We consider here a dataset with flux and velocity data of vehicles moving on a highway, collected by fixed sensors and classified by lane and by class of vehicle. By means of a machine learning model based on an LSTM recursive neural network, we extrapolate two important pieces of information: 1) if congestion is appearing under the sensor, and 2) the total amount of vehicles which is going to pass under the sensor in the next future (30 min). These pieces of information are then used to improve the accuracy of an LWR-based first-order multi-class model describing the dynamics of traffic flow between sensors. The first piece of information is used to invert the (concave) fundamental diagram, thus recovering the density of vehicles from the flux data, and then inject directly the density datum in the model. This allows one to better approximate the dynamics between sensors, especially if an accident happens in a not monitored stretch of the road. The second piece of information is used instead as boundary conditions for the equations underlying the traffic model, to better reconstruct the total amount of vehicles on the road at any future time. Some examples motivated by real scenarios will be discussed. Real data are provided by the Italian motorway company Autovie Venete S.p.A., Comment: 38 pages

International audience; The interactions of iodine and caesium in UO2 have been investigated. For this purpose, implanted UO2 samples were thermally treated (4h at 900°C or 1h at 1200°C) under controlled atmosphere (0.03% H2O/H2) and then characterized by several experimental techniques for their structural and chemical studies. Thermodynamic calculations were also performed in order to optimize heat treatment conditions before performing tests, and to help in the interpretation of results afterwards. The sample characterizations after thermal treatments reveal the presence of bubbles and precipitates (mean diameter around 10 - 20 nm) and have allowed to clearly identify the presence of CsI in these bubbles which is in agreement with the calculations. The chemical form of the observed precipitates is not well defined yet, due to the lack of experimental reference spectra, but they consist very likely of caesium uranates, as predicted by the thermodynamic calculations.

International audience; A numerically effective approach was developed for the modeling of spray-drying of colloidal suspensions. This approach was based on the integration of two models. The first is a phenomenological and radially symmetric model accounting for the drying of single-droplets, while the second employs computational fluid dynamics (CFD) simulations to account for the gas flow conditions and atomization in a spray dryer. Experiments were also conducted on single suspension droplets trapped in an acoustic field as well as on droplets in a mini-spray dryer. The predictions of the models were found to be in reasonable agreement with the experimental data, in terms of droplet shrinking and buckling, particle yield, and spatial distribution in the spray dryer mockup.

International audience; •The coupled influence of the intense electronic and nuclear energy deposition on the defect production were investigated in UO2.•The evolution of local disorder (evaluated by Raman) and the stress level (determined by XRD) on fluorite-type oxides ceramics under the effect of intense electronic excitation was followed.•A possible synergetic effect between the pre-existing defects and those generated by intense electronic ionizations was revealed. The coupled effects of nuclear and electronic energy losses were investigated in uranium dioxide (UO2). Single and sequential ion irradiations were carried out with 92 MeV Xe ions and 0.9 MeV I ions. Raman spectroscopy and X-ray diffraction analyses were combined with the inelastic thermal spike (iTS) model to investigate the effect of electronic ionizations on the ballistic damage. It appears that the high-energy ions induce a significant change in the defect distribution with an amplitude that depends on the level of pre-existing disorder. This modification essentially results in an acceleration of the transformation from the dislocation loops to the dislocation lines, a process that is accompanied by a stress relaxation. Surprisingly, with the fluence increase of 92 MeV Xe ions, the stress starts to increase again, highlighting a possible synergetic effect between the pre-existing defects and those generated by the 92 MeV Xe ions irradiation.

The HIrisPlex-S system, targeting a total of 41 SNPs, allows the simultaneous eye, hair and skin color prediction from DNA. In the present study, we developed a massive parallel sequencing (MPS) multiplex assay in order to genotype all the HIrisPlex-S markers in degraded casework samples. PCR amplicons sizes of target regions were kept below 180 bp, in order to allow analysis of degraded DNA samples. Individuals with known phenotype, artificially degraded DNA samples and a set of 2800M control DNA dilutions were sequenced on a Ion PGM System, in order to evaluate the concordance testing results and the forensic suitability of this 41-plex MPS assay. Full and reliable profiles could be obtained with 0.1 ng of input DNA. The increment of the number of PCR cycles results in improvement of sensitivity or in typing results but an increase of artifacts were also observed.

Friedmanniomyces endolithicus is a highly melanized fungus endemic to the Antarctic, occurring exclusively in endolithic communities of the ice-free areas of the Victoria Land, including the McMurdo Dry Valleys, the coldest and most hyper-arid desert on Earth and accounted as the Martian analog on our planet. F. endolithicus is highly successful in these inhospitable environments, the most widespread and commonly isolated species from these peculiar niches, indicating a high degree of adaptation. The nature of its extremo tolerance has not been previously studied. To investigate this, we sequenced genome of F. endolithicus CCFEE 5311 to explore gene content and genomic patterns that could be attributed to its specialization. The predicted functional potential of the genes was assigned by similarity to InterPro and CAZy domains. The genome was compared to phylogenetically close relatives which are also melanized fungi occurring in extreme environments including Friedmanniomyces simplex, Baudoinia panamericana, Acidomyces acidophilus, Hortaea thailandica and Hortaea werneckii. We tested if shared genomic traits existed among these species and hyper-extremotolerant fungus F. endolithicus. We found that some characters for stress tolerance such as meristematic growth and cold tolerance are enriched in F. endolithicus that may be triggered by the exposure to Antarctic prohibitive conditions.

This paper reports numerical and practical results of an open-loop optimal control formulation that reduces the power consumption of the electric arc furnace (EAF) steel production process. A control vector parametrization technique is used to optimize the batch trajectory with the goal to minimize the energy losses of the process. First principles models are utilized to describe the dynamics, as well as the influence of the voltage and impedance set-points on the process. The results of the dynamic optimization provided a sequence of set-points (called a melting profile) that aligns well with intuition: the profile utilizes high power levels during the high efficiency stages of the process, and low power levels as the batch moves towards a more energy inefficient state. The benefits of the proposed optimized mode of operation are demonstrated by an experimental study case. An optimal melting profile was calculated and implemented in a fully operative ultra-high power EAF. For a series of 19 test batches, the energy consumption and the batch time of the process were reduced by 4.5% and 4.6% for one type of steel.

Transmission electron microscopy experiments coupled with 4 MeV Au and 390 keV Xe implantations were conducted on polycrystalline UO2 thin foils in order to study the void change with damage, temperature (ranging from −180 to 1100 °C) and exogenous xenon atoms incorporation. Void size is weakly dependent on the ion dose in the range of [0.01–10] × 1014 i/cm2, whereas void density increases strongly at the early beginning of irradiation and then saturates after 3–4 × 1013 i/cm2. Change in void size and density are shown as weak functions of temperature and xenon atoms incorporation in these experimental conditions. These results indicate a heterogeneous void nucleation and a change monitored by ballistic effects. Studying voids is very tricky. This work also highlights the strong dependence of the measured void size on the TEM settings and capabilities. Thus, it is important to discuss only data obtained in the same conditions to derive influence parameters.

In restoration and conservation practices, biocide treatments are considered one of the most practical approaches to remove biological colonization on artworks, including stone. Numerous studies have focused on the short- and long-term effects of these treatments and recently many alternative methods to reduce their potential hazards to human health and the environment have been proposed. In this study, a solvent gel containing dimethyl sulfoxide (DMSO), already used to clean paintings, was applied on colonized marble artifacts at the monumental cemetery of Bonaria (Cagliari – Italy) to remove biological patinas. The protocol efficiency was evaluated by scanning electronic microscopy, rugosimetric and colorimetric measurements and growth tests. A comparative study also was performed to validate the method using biocides currently used in conservation. The results demonstrate that DMSO solvent gel is efficient at removing patinas on stone, of low impact, easy to use, inexpensive and can be considered a more practical alternative to biocide treatments.

Despite living organisms are not exposed to acute ionizing radiation under natural conditions, some exhibit a high radiation resistance. Understanding this phenomenon is important for assessing the impact of radiation-related accidents, occupational exposures and space missions. In this context, in this study we analyzed the effect of gamma rays on the Antarctic cryptoendolithic melanized fungus Friedmanniomyces endolithicus CCFEE 5208 and demonstrated its resistance to acute doses of gamma radiation (up to 400 Gy), accompanied by increase in metabolic activity.

Loss-of-function mutations in proline-rich transmembrane protein 2 (PRRT2) cause paroxysmal disorders associated with defective Ca2+ dependence of glutamatergic transmission. We found that either acute or constitutive PRRT2 deletion induced a significant decrease in the amplitude of evoked excitatory postsynaptic currents (eEPSCs) that was insensitive to extracellular Ca2+ and associated with a reduced contribution of P/Q-type Ca2+ channels to the EPSC amplitude. This synaptic phenotype was paralleled by a decrease of somatic P/Q-type Ca2+ currents due to a decreased membrane targeting of the channel with unchanged total expression levels. Co-immunoprecipitation assays and proteomic screens revealed an interaction between PRRT2 and P/Q-type Ca2+ channels. At presynaptic terminals lacking PRRT2, P/Q-type Ca2+ channels reduce their clustering at the active zone, with a corresponding decrease of the P/Q-dependent presynaptic Ca2+ signal. The data highlight the central role of PRRT2 in assuring the physiological Ca2+ sensitivity of the release machinery at glutamatergic synapses.

In this work, high resolution transmission electron microscopy and numerical simulation at the atomic scale were coupled, for the first time to our knowledge, to study the atomic structure of two Σ5 symmetric tilt grain boundaries in uranium dioxide (UO2) bicrystals. We show that whereas the Σ5 (021)/[100] is fully symmetric, with the grain boundary plane forming a mirror symmetry plane, a rigid body translation exists between the crystals in the Σ5 (031)/[100]. We particularly believe that the excellent agreement between experimentally observed and simulated structures highlights the relevance of the coupled approach. Such result emphasize that the use of CRG and Yakub empirical potentials including a Morse contribution can be relied upon to model the behavior of UO2.