3D-printed system optimizing dissolution of hyperpolarized gaseous species for micro-sized NMR

International audienceDissolution of hyperpolarized species in liquids of interest for NMR is often hampered by the presence of bubbles that degrade the field homogeneity. Here a device constituted by a bubble pump and a miniaturized NMR cell fitting both inside the narrow bore of an NMR magnet is built by 3D printing. 129Xe NMR experiments performed with hyperpolarized xenon reveal high and homogeneous dissolution of the gas in water

Contraction of the ITCPN state space

We show here how to contract the ITCPN state space. We distinguish three levels of contraction that translate the ITCPN state space into one well timed and coherent timed automation. We consider here only equivalence based on delays. To achieve more contractions, the equivalence based on delays can be completed with equivalence based on colours as shown in [4

On Negotiation as Concurrency Primitive

We introduce negotiations, a model of concurrency close to Petri nets, with multiparty negotiation as primitive. We study the problems of soundness of negotiations and of, given a negotiation with possibly many steps, computing a summary, i.e., an equivalent one-step negotiation. We provide a complete set of reduction rules for sound, acyclic, weakly deterministic negotiations and show that, for deterministic negotiations, the rules compute the summary in polynomial time

The derivation of performance expressions for communication protocols from timed Petri net models

Petri Net models have been extended in a variety of ways and have been used to prove the correctness and evaluate the performance of communication protocols. Several extensions have been proposed to model time. This work uses a form of Timed Petri Nets and presents a technique for symbolically deriving expressions which describe system performance. Unlike past work on performance evaluation of Petri Nets which assumes a priori knowledge of specific time delays, the technique presented here applies to a wide range of time delays so long as the delays satisfy a set of timing constraints. The technique is demonstrated using a simple communication protocol

Ion track grafting: A way of producing low-cost and highly proton conductive membranes for fuel cell applications

International audienceKeywords: Ion track grafting Radiografting Swift heavy ions Proton conductivity Polymer electrolyte membrane Proton exchange membrane fuel cell a b s t r a c t Proton conductive individual channels through a poly(vinyl di-fluoride) PVDF matrix have been designed using the ion track grafting technique. The styrene molecules were radiografted and further sulfonated leading to sulfonated polystyrene (PSSA) domains within PVDF. The grafting process all along the cylindrical ion tracks creates after functionalisation privileged paths perpendicular to the membrane plane for proton conduction from the anode to the cathode when used in fuel cells. Such ion track grafted PVDF-g-PSSA membranes have low gas permeation properties against H 2 and O 2. A degree of grafting (Y w) of 140% was chosen to ensure a perfect coverage of PSSA onto PVDF-g-PSSA surface minimizing interfacial ohmic losses with the active layers of the Membrane Electrolyte Assembly (MEA). A three-day fuel cell test has been performed feeding the cell with pure H 2 and O 2 , at the anode and cathode side respectively. Temperature has been progressively increased from 50 to 80 • C. Polarisation curves and Elec-trochemical Impedance Spectroscopy (EIS) at different current densities were used to evaluate the MEA performance. From these last measurements, it has been possible to determine the resistance of the MEA during the fuel cell tests and, thus the membrane conductivity. The proton conductivities of such membranes estimated during fuel cell tests range from 50 mS cm −1 to 80 mS cm −1 depending on the operating conditions. These values are close to that of perfluorosulfonated membrane such as Nafion ® in similar conditions

In vivo time-lapse imaging of mitochondria in healthy and diseased peripheral myelin sheath

The myelin sheath that covers a large amount of neurons is critical for their homeostasis, and myelinating glia mitochondria have recently been shown to be essential for neuron survival. However morphological and physiological properties of these organelles remain elusive. Here we report a method to analyze mitochondrial dynamics and morphology in myelinating Schwann cells of living mice using viral transduction and time-lapse multiphoton microscopy. We describe the distribution, shape, size and dynamics of mitochondria in live cells. We also report mitochondrial alterations in Opa1(delTTAG) mutant mice cells at presymptomatic stages, suggesting that mitochondrial defects in myelin contribute to OPA1 related neuropathy and represent a biomarker for the disease