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Ultrafast methods have the ability to transiently decouple transitions between subsystems that evolve simultaneously at thermal equilibrium. Here, time-resolved X-ray diffraction reveals a time delay between volumetric and spin-state switching in a spin-crossover compound.

The Rb0.94Mn0.94Co0.06[Fe(CN)6]0.98 material was designed to exhibit a 75 K wide thermal hysteresis around room temperature, associated with a bistability between the low temperature MnIIIFeII tetragonal phase and the high temperature MnIIFeIII cubic phase. We have recently shown that a single laser pulse can be used to drive, at room temperature, the photoinduced phase transition from the MnIIIFeII tetragonal phase to the MnIIFeIII cubic phase. By using a specific powder sample streaming technique, we could monitor by time‐resolved X‐ray diffraction how the ultrafast out‐of‐equilibrium dynamics, imposed by the structural relaxation around the local photoinduced charge transfer, changes with the fluence of the laser pulse. In this paper we present a detailed structural analysis of the crystalline reorganizations associated with the charge‐transfer in different regimes of photoexcitation. In the low excitation polaronic regime, the photoinduced charge transfer is local and accompanied by an anisotropic distortion of the Mn coordination sphere and of the tetragonal lattice. In the high excitation regime, a macroscopic and cooperative charge‐transfer phase transition occurs towards the cubic lattice, where the coordination around the Mn reaches octahedral symmetry. [ABSTRACT FROM AUTHOR]

Spin‐crossover (SCO) complexes have drawn significant attention for the possibility to photoswitch their electronic spin state on a sub‐picosecond timescale at the molecular level. However, the multi‐step mechanism of laser‐pulse‐induced switching in solid state is not yet fully understood. Here, time‐resolved synchrotron X‐ray diffraction is used to follow the dynamics of the crystal lattice in response to a picosecond laser excitation in nanometric thin films of the SCO complex [Fe(HB(1,2,4‐triazol‐1‐yl)3)2]. The observed structural dynamics unambiguously reveal a lattice expansion on the 100 picosecond timescale, which is temporally decoupled both from the ultrafast molecular photoswitching process (occurring within 100 fs) and from the delayed, thermo‐elastic (Arrhenius‐driven) conversion (taking place ≈10 ns). These time‐separated dynamics are also manifested by the observation of damped acoustic oscillations in the time evolution of the lattice volume, whereas no such oscillations are observed in the electronic spin‐state dynamics. Overall, these results suggest the existence of a universal behavior whereby the intramolecular energy barrier between low‐spin and high‐spin states acts as an intrinsic dynamical bottleneck in the out‐of‐equilibrium spin‐state switching dynamics of SCO materials. [ABSTRACT FROM AUTHOR]

This work summarizes neutronic calculations performed for the CALORRE differential calorimeter specifically designed by Aix Marseille University to inform the irradiation campaign planning for testing in MITR within the framework of the CALOR-I research program. MCNP software was used to predict the neutron and gamma flux spectrum, and total nuclear heating rate to the components of the calorimeter in a variety of positions. Results were compared to evaluate spatial bias, core loading effects, optimization for axial position, and provide input data for thermal multi-physics modelling.

This paper presents the preliminary characterization of a new reduced-height CALORRE differential calorimeter designed and fabricated for the irradiation in the MITR within the framework of the CALOR-I program. The paper begins by focusing on the preparation of the irradiation campaign, providing a brief and concise description of the MITR core and the newly fabricated differential calorimeter assembly. Next, the paper presents the preliminary experimental characterization conducted under laboratory conditions. This section includes a detailed presentation of the updated experimental set-up and the key metrological characteristics of the sensor response obtained from the first experimental results. Furthermore, the paper estimates and highlights the responses of the calorimeter calculated by means of a 3-D numerical thermal model under real conditions considering local heat sources determined by the NRL of the MIT using MCNP code. In conclusion, the paper offers some final remarks and prospects to realize the irradiation campaign successfully.

This paper presents the study of a new innovative heat flow single-cell calorimeter dedicated to the measurement of the nuclear heating rate in research reactors. Before irradiating this type of sensor, it is necessary to characterize it under laboratory conditions to determine its metrological properties. A general description (design, geometry and materials nature) of this new calorimeter will be given, focusing on the motivations that led to its development. This part will be followed by a presentation of the experimental set-up and operating protocol used to characterize this sensor. The sensor sensitivity and response time will be quantified and discussed with a comparison of those obtained with previous calorimeters. In parallel with these experimental characterizations, parametric 3-D numerical simulations will be carried out using COMSOL Multiphysics software. These results, obtained both experimentally and numerically, will be compared to present a complete calorimeter study under laboratory conditions.

Background: Associated infections with sanitary care are related with patient mortality and high cost in the Intensive Care Unit. Objective: Identify the more frequently germs in culture anddrug resistance. Methods: A prospective and descriptive epidemiological research was developed in the Joaquin Albarran ICU from January of 2015 to December of 2018. In the1847 cultures made only in 654 the germen was isolated. For statistical analysis, an information database was created using the 22th version of SPPS program, the X² test, Value of the p< 0.05 were considered significant. Results: Klebsiella sppwas the most frequently germen in 31, 0%, following byStaphylococcus spp ( 24, 5%), and E. coli in 9, 8 %.in the respiratory secretion , Klebsiella spp was isoled in 45,1 %.Staphylococcus spp was present in 53,6% in blood culture and in the urine culture Candida spp was present in 41,1% following by E.coli in 27,0 %.Colistine was the most useful drug for treatment patient with Klebsiella spp ,E.coli,Acinetobacter and Pseudomona spp .In the cases of Staphylococcus spp, Vancomicine was the best choice. Conclusions: Klebsiella sppwas the most frequently germen in intensive care unit and in the respiratory secretion, Staphylococcus spp was present in the majority of blood culture. In the urine culture analyzed, Candida spp was the principal germs. Colistine was the successful drug for gram negative germ and vancomicine for gram positive germs.

This paper presents an experimental study of the calibration of a non-adiabatic single-cell calorimeter called KAROLINA. This type of sensor is used to quantify the nuclear heating rate inside MTRs (Material Testing Reactors). The calibration of this sensor type is carried out in laboratory conditions without irradiation. The calibration corresponds to a preliminary step, which is crucial to use this sensor in real conditions. In the case of the studied single-cell calorimeter owning no heating element, the calibration is realized with a specific test bench, called BERTAN, based on thermal transient regimes. First of all, the paper describes the methodology of the determination of the calorimeter sensitivity and the dedicated experimental set-up developed recently. Then the paper is devoted to a parametric study carried out on the KAROLINA single-cell calorimeter to determine the influence of several parameters on its thermal time constant (temperature, velocity, phase, method).

Neutron detection is a relevant topic in the field of nuclear instrumentation. It is at the heart of the concerns for fusion applications (neutron diagnostics, measurements inside the Test Blanket Modules TBM) as well as for fission applications (in-core and ex-core monitoring, neutron mapping or safety applications in research reactors). Moreover, due to the even more harsh conditions of the future experimental reactors such as the Jules Horowitz Reactor (JHR) or International Thermonuclear Experimental Reactor (ITER), neutron detectors need to be adapted to high neutron and γ fluxes, high nuclear heating rates and high temperatures. Consequently, radiation and temperature hardened sensors with fast response, high energy resolution and stability in a mixed neutron and γ environment are required. All these requirements make wide-bandgap semiconductors and, more precisely, Silicon Carbide (SiC) serious candidates due to their intrinsic characteristics in such extreme environments. Thus, since the last decades, SiC-based detectors are developed and studied for neutron detection in various nuclear facilities. In this paper, a SiC-based neutron detector is 3-D designed and studied through thermal and radiation-matter interaction numerical simulations for a future irradiation campaign at the Jožef Stefan Institute TRIGA Mark II research reactor in Slovenia. Firstly, this paper presents the scientific background and issues of our SiC-based detectors. In a second part the 3-D geometry is shown. Thereafter, the 3-D numerical thermal simulation results are reported. Finally, the 3-D numerical radiation/matter interaction simulations results are presented.

This paper deals with the CALORRE differential calorimeter patented by Aix-Marseille University and the CEA in 2015. Firstly, the paper focuses on the presentation of the first prototype of CALORRE calorimeter qualified under real conditions during the MARIA irradiation campaign in 2015. Then, a review of the studies restricted to one CALORRE calorimetric cell realized thanks to experimental characterizations under laboratory conditions is detailed. Several configurations were studied to determine the influence of the cell height, its horizontal fin geometry and the nature of the material of its structure on its response for a calibration protocol: linearity, sensitivity, range, reproducibility, response time and absolute temperatures. Finally, within the framework of the new CALORI project, an optimization of the calorimeter assembly and its design were carried out in order to remove contact thermal resistances and provide a new configuration of CALORRE calorimeter suited for the in-core water loop of the MIT reactor (2 W.g-1). The response of this new calorimeter is estimated thanks to thermal simulations.