Epidemiological studies have revealed a potential of low doses (< 500mGy) of gamma-radiation to induce cardiac pathologies, such as circulatory disease and ischemia. Involvement of Arrythmias in this pathological context is less clear. Indeed the development of arrythmia is reported in some but not all epidemiological studies (internal 137-Cesium (137Cs) exposure). The controversies can be attributed to the lack of understanding of the underlying mechanisms involved. Arrhythmias may be caused by an imbalance between stimulation of the sympathetic nervous system and inhibition by the parasympathetic. The objective of this project is to identify the signalling pathways involved in cardiac pathologies after exposure and over time. The study hypothesis would be that exposure to low doses of gamma-radiation induces tissue and nerve remodelling in the heart. We exposed C57Bl/6J male mice to whole-body single external doses ranging from 50 to 2000mGy from a 137Cs gamma-radiation source. Two post-exposure time points were studied (4 hours and 3 months). The heart function was monitored by Doppler ultrasound examination. Signalling pathways were examined by measuring levels of proteins involved in various cardiac functions by Western blotting and Sirius red staining of histological sections. In all, 4 hours after exposure, Western blot analysis showed a significant decrease in the expression of proteins involved in the conduction of cardiac nerve influx (Connexins 43 at 100 and 250mGy; P-value < 0.05) and in the synthesis of catecholamines (Tyrosine Hydroxylase at 50 and 250mGy; P-value < 0.05). These decreases may be responsible for heart contraction problems. Conversely, at 3 months post-exposure, we observed a significant increase in the levels of these same proteins of interest (Connexins 43 and Synapsin at 500 and 2000mGy; P-value < 0.05) which could induce long-term arrhythmia. These protein expression changes were observed only in the atrium and right ventricle. In addition, we observed interstitial fibrosis in the hearts of the mice exposed to the same doses (P-value < 0.05). Lastly, we observed a significant increase in the percentage of muscularized pulmonary arterioles (at 500mGy; P-value < 0.05), indicating the development of pulmonary hypertension. In summary, our results suggest that a single external exposure to a low dose of gamma rays can induce long-term functional alteration in the heart and that a potential dose threshold for such effect is below 500mGy.

The "Young Club" of the French Society for Radiation Protection organized its first conference in April 2018, under the theme of: "Radiation protection: What innovations? What future?". Bringing together more than fifty participants, this first conference was organized in two stages with (i) plenary presentations in the morning and (ii) two workshops on how innovation can contribute to the future of radiation protection in the afternoon. This article aims to present the main elements highlighted during the discussions of these two workshops. Discussions raised indeed the need to consider the development of new technologies and to analyse their possible applications in the fields of radiation protection, whether in the medical field or environmental monitoring. And beyond that, participants also emphasized the need to set up innovative tools which could contribute to the promotion of a radiation protection culture and a better sharing of data. Regarding these key issues, various actions have been suggested and could be deemed as potential future actions for the "Young Club".

Le Club des Jeunes Sociétaires de la Société Française de Radioprotection a organisé sa première journée scientifique en avril 2018, avec pour thème : « Radioprotection : Quelles innovations ? Quel avenir ? ». Réunissant plus d’une cinquantaine de participants, cette première journée s’est déroulée en deux temps avec des présentations plénières le matin et des ateliers de réflexion l’après-midi portant sur la manière dont l’innovation peut contribuer à la progression ainsi qu’à l’avenir de la radioprotection. Cet article présente les principaux éléments ressortis lors des discussions de ces deux ateliers. Les échanges ont mis en avant la nécessité de prendre en compte le développement des nouvelles technologies et d’en étudier leurs possibles applications aux champs de la radioprotection, que ce soit dans le domaine médical ou de la surveillance environnementale. Mais au-delà, les participants ont plus particulièrement insisté sur le besoin de déployer des outils innovants se plaçant au service de la promotion d’une culture de radioprotection et d’un meilleur partage des données. Pour ces deux enjeux, différentes actions ont été proposées et constituent ainsi des pistes d’actions dont le Club des Jeunes Sociétaires pourrait s’emparer à l’avenir.

Correction for 'Site selective analysis of Nd3+–Lu3+ codoped CaF2 laser crystals' by S. Normani et al., CrystEngComm, 2016, 18, 9016–9025.

Preliminary CW laser results with a 5%Yb:2%Tm:CaF2 single crystal are obtained at 1.85μm with a 140mW output power and a 17% laser slope efficiency by pumping at 980 nm with a high brightness fiber laser.

Co-doping Nd:CaF2 crystals with Y3+ and Lu3+ ions significantly improves their spectral properties and laser performance. The spectral profiles simplify and get wider, the quantum yields increase and efficient laser operation is obtained at 1.055µm.

We demonstrate that codoping Nd:CaF2 single crystals with Y3+ and Lu3+ nonoptically active ions significantly improves their absorption, emission, and fluorescence lifetime properties and their laser performance. The spectral profiles get smoother and wider, wider than that found with standard Nd:glasses; the quantum yields increase; and efficient laser operation is obtained around 1.055 μm.

The codoping of KY3F10 with Pr3+ and Yb3+ ions is investigated as a possible quantum cutting system to enhance solar cells efficiency. For one visible photon absorbed by Pr ions, two ytterbium ions are expected to be excited by two consecutive energy transfers. The subsequent emission of two infrared photons reduces thus the thermalization losses usually observed in Si solar cells. Emission spectra and lifetime decays in KY3F10 doped with 0.5% Pr3+ and codoped with 0%, 1%, 10% and 20% Yb3+ show an increase of the energy transfer efficiency from Pr3+ to Yb3+ with the Yb3+ concentration. For the first Pr3+ to Yb3+ energy transfer, an efficiency close to 100% is achieved in KY3F10: 0.5%Pr3+, 20%Yb3+. However, this promising result faces challenging issues since an increase in Yb concentration induces energy migration between Yb3+ ions which impairs the Yb3+ luminescence.

Yb3+ doped CaF2 has been proved in the last years to be one of the most attractive Yb3+ doped materials for broadly tunable, high power and short-pulse laser operation as well as for bi-frequency laser and THz wave generation. Interesting results were also obtained by using Yb3+:CaF2 as regenerative amplifier of femtosecond pulses in the mJ level with very high damage threshold and, even more recently, prove was made that cryogenically cooled materials could lead to even more promising performance at high power levels. The purpose of the present paper consists first in a clarification of a number of luminescence, thermal and laser properties as well as in the description of the most recent laser results, obtained in particular at low temperature.

The presentation will give the state of the art and the results of the last advances obtained in the growth, the characterization and the implementation of three kinds of rare-earth doped halide laser crystals: Pr3+ doped fluorides, Yb3+ doped CaF2 and its isotypes, and Er3+ and Pr3+ doped chloride and bromide KPb2Cl5 and Tl3PbBr5.

Femtosecond mode-locked operation is demonstrated for the first time, to our knowledge, with a Yb:SrF(2) crystal. The shortest pulse duration is 143 fs for an average power of 450 mW. The highest average power is 620 mW for a pulse duration of 173 fs. Since Yb:SrF(2) corresponds to the longest-lifetime Yb-doped crystal with which the mode-locking operation has been achieved, a detailed analysis is carried out to characterize the quality of the solitonlike regime.

Er3+-doped single crystalline laser rods were successfully grown by the Bridgman-Stockbarger method using silica ampoules sealed under HCl gas. Modified material synthesis and ampoule preparation processes have been developped that eventually led to crack- and bubble-free eight centimeters-long laser crystals.

We report on a comparative study of the spectroscopic and thermo-mechanical properties and of the laser slope efficiencies and laser tuning ranges of three Yb3+ doped CaF2, SrF2 and BaF2 single crystals grown in the same conditions.

We report an in situ thermal study of Yb-doped fluorite crystals Yb:CaF(2) and Yb:SrF(2) under high power pumping, with or without laser operation. The experiment combines simultaneously thermography and measurement of the thermal aberrations. This setup allows us to measure temperature gradients, thermal lens, and absorption coefficients. From these measurements, we evaluate the thermal conductivity, fractional thermal load, and thermo-optic coefficient. Great differences are observed between the lasing and non lasing regimes. Our measured thermal lenses are greater than what are expected from the thermo-optic parameters found in previous work. Based on this thermal study, we design a laser cavity operating with large output power and TEM(00), leading to better performances for Yb:CaF(2) than Yb:SrF(2).