Titanium Nitride Coating of RF Ceramic Windows by Reactive DC Magnetron Sputtering

International audienceLAL-Orsay is developing an important effort on R&D and technology studies on RF power couplers for superconductive cavities. These are complex and high technology devices due to their basic functions: vacuum and temperature separation form the environment to the cavity. One of the most critical components of high power couplers is the ceramic RF window that allows the power flux to be injected in the coaxial line. The presence of a dielectric window on a high power RF line has in fact a strong influence on the multipactor phenomena, a resonant electron discharge that is strongly limiting for the RF components performances. The most important method to reduce the multipactor is to decrease the secondary emission yield of the ceramic window. Due to its low secondary electron emission coefficient, TiN thin film is used as a multipactor suppressor coating on RF ceramic coupler windows. In the framework of the EU program FP6 the LAL-Orsay and the LNL-Legnaro establish a collaboration to develop a coating bench that takes into account the different strong constraints on stoechiometry and film coating thickness given by coupler operating conditions. Reactive magnetron sputtering technology was chosen to obtain such deposit. A full description of a sputtering bench recently installed in LAL, and its main characteristics are given. Stoechiometric TiN films are obtained by optimization of reactive gas flow (N2), for a given bias and a given ionisation gas flow (Ar). XRD analysis was performed to control film composition. From the data obtained, lattice parameter is calculated for each deposit and film stoechiometry is determined. XPS analysis of stoechiometric film had shown the existence of oxygen and carbon mainly in the surface. However, it shows also that the ratio Ti/N in atomic percentage is equal to 1

Radioisotopic purity and imaging properties of cyclotron-produced 99mTc using direct 100Mo(p,2n) reaction

Evaluation of the radioisotopic purity of technetium-99m (99mTc) produced in GBq amounts by proton bombardment of enriched molibdenum-100 (100Mo) metallic targets at low proton energies (i.e. within 15\u201320 MeV) is conducted. This energy range was chosen since it is easily achievable by many conventional medical cyclotrons already available in the nuclear medicine departments of hospitals. The main motivation for such a study is in the framework of the research activities at the international level that have been conducted over the last few years to develop alternative production routes for the most widespread radioisotope used in medical imaging. The analysis of technetium isotopes and isomeric states (9xTc) present in the pertechnetate saline Na99mTcO4 solutions, obtained after the extraction/purification procedure, reveals radionuclidic purity levels basically in compliance with the limits recently issued by European Pharmacopoeia 9.3 (2018 Sodium pertechnetate (99mTc) injection 4801\u20133). Moreover, the impact of 9xTc contaminant nuclides on the final image quality is thoroughly evaluated, analyzing the emitted high-energy gamma rays and their influence on the image quality. The spatial resolution of images from cyclotron-produced 99mTc acquired with a mini-gamma camera was determined and compared with that obtained using technetium-99m solutions eluted from standard 99Mo/99mTc generators. The effect of the increased image background contribution due to Compton-scattered higher-energy gamma rays (E \u3b3 \u2009\u2009>\u2009\u2009200\u2009keV), which could cause image-contrast deterioration, was also studied. It is concluded that, due to the high radionuclidic purity of cyclotron-produced 99mTc using 100Mo(p,2n)99mTc reaction at a proton beam energy in the range 15.7\u201319.4 MeV, the resulting image properties are well comparable with those from the generator-eluted 99mTc

Utilização de chuveiros na sala pré-ordenha e sua influência na produtividade de búfalas da raça Murrah (Bubalus bubalis).

O estudo foi realizado com 64 búfalas, em dois tratamentos (1 e 2), durante seis dias. No primeiro, antes da ordenha, os animais permaneceram 1h em sala de espera com acesso ao chuveiro No segundo, os animais não tiveram acesso ao chuveiro. Foram registrados Índice de Temperatura de Globo e Umidade (ITGU) e a Umidade Relativa (UR) das salas de ordenha e de espera, Temperatura de Corpo (TC), Frequência Respiratória (FR), Reatividade (REAT), Nível de Estresse (NEST) e a Produção Diária de Leite (PL). Os dados foram analisados com o auxílio do programa SAS. O efeito da FR não foi significativo (P>0,57) sobre a PL. Não houve diferença significativa na PL para a REAT. O NEST foi o mesmo nos dois tratamentos. As regressões da característica (PL_AJ) sobre ITGU Interno (ITGU_I), ITGU Externo (ITGU_E), TC e UR não foram significativas (P>0,12). No tratamento 2 foram observados maior número de animais em classes de estresse, verificou-se que o tratamento 1 possibilitou a mudança ( alguns animais) da zona de alerta ou estresse para a zona de conforto térmico em relação ao ITGU_I. No tratamento 2, todos os animais estavam em estresse térmico. Os animais submetidos ao estresse calórico em ambas as situações utilizaram com eficiência o seu sistema termorregulador, sem interferir na produção de leite

Short-term economic impact of the Zika virus outbreak

Summary Zika virus (ZIKV) is mainly transmitted by mosquitoes bites. However, transmission by sexual contacts has been reported in 11 non endemic countries. The rapid spread of ZIKV in Latin American and Caribbean Countries (LCR), person-to-person transmission and perceived risk on people’s well being can affect the emerging economies of LCR which historically dependent on truism. Here we present an analysis on economic outputs for assessing the current impact of ZIKV on markets. Our analysis show an unexpected resilience of LCR markets to international alerts. This positive response represents an opportunity to scale-up interventions for preventing the further spreading of the ZIKV epidemic

The effectiveness of protection systems toward rockfall risk mitigation

Hazard

A deep-learning approach to parameter fitting for a lithium metal battery cycling model, validated with experimental cell cycling time series

Symmetric coin cell cycling is an important tool for the analysis of battery materials, enabling the study of electrode/electrolyte systems under realistic operating conditions. In the case of metal lithium SEI growth and shape changes, cycling studies are especially important to assess the impact of the alternation of anodic–cathodic polarization with the relevant electrolyte geometry and mass-transport conditions. Notwithstanding notable progress in analysis of lithium/lithium symmetric coin cell cycling data, on the one hand, some aspects of the cell electrochemical response still warrant investigation, and, on the other hand, very limited quantitative use is made of large corpora of experimental data generated in electrochemical experiments. This study contributes to shedding light on this highly technologically relevant problem, thanks to the combination of quantitative data exploitation and Partial Differential Equation (PDE) modelling for metal anode cycling. Toward this goal, we propose the use of a Convolutional Neural Network-Long-Short Term Memory (CNN-LSTM) to identify relevant physico-chemical parameters in the PDE model and to describe the behaviour of simulated and experimental charge–discharge profiles. Specifically, we have carried out parameter identification tasks for experimental data regarding the cycling of symmetric coin cells with Li chips as electrodes and LP30 electrolyte. Representative selection of numerical results highlights the advantages of this new approach with respect to traditional Least Squares fitting

Cryphonectric acid and other minor metabolites from a hypovirulent strain of Cryphonectria parasitica

Investigations carried out on secondary metabolites produced in culture by a hypovirulent strain of Cryphonectria parasitica allowed the isolation of several compounds which were characterized by NMR analysis and derivatization reactions. The most abundant metabolite was a new compound, called cryphonectric acid (1). Other metabolites were diaporthin, the only known phytotoxic compound isolated from both virulent and hypovirulent strains of C. parasitica, (+)-orthosporin, and L-p-hydroxyphenyllactic acid (HOPLA). Root growth activity of the purified compounds was evaluated both on tomato seedlings and maize subapical segments