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In order to progress in the development of Lead-cooled Fast Reactors, from the safety point of view it is essential to understand the chemical compatibility between liquid lead and uranium oxide. In the present work, entropy and heat capacity of Pb3U11O36, a possible ternary compound coming from fuel-coolant chemical interaction, were determined for the first time. Entropy at 298.15 K was obtained from low temperature heat capacity measurements using the Physical Property Measurement System (PPMS) in the temperature range 2–300 K, while the high temperature heat capacity has been measured by a drop calorimeter from 373 K to 1200 K. The experimental thermodynamic properties were compared with the values computed by means of DFT-GGA simulations, obtaining a very good agreement.

A new neptunium intermetallic compound, NpPt 2 In 7 , has been synthesized in polycrystalline form and characterized by several macroscopic techniques. A Rietveld analysis of its powder X-ray diffraction pattern shows that NpPt 2 In 7 crystallizes in a tetragonal lattice with I 4/ mmm symmetry and lattice parameters a = 4.58471 ( 3 ) A, c = 21.5065 ( 3 ) A. Magnetic susceptibility, electrical resistivity, Hall effect, and heat capacity measurements indicate a metallic character and the occurrence of antiferromagnetic order below a Neel temperature T N = 23 K. The transition is exceptionally robust and T N decreases by 0.2 K under a magnetic field of 9 T. A modified Curie-Weiss fit of the high-temperature magnetic susceptibility curve χ ( T ) gives an effective magnetic moment μ e f f = 2.54 μ B close to the value expected for trivalent Np. Low temperature heat capacity measurements give a reduced Sommerfeld linear coefficient close to 25 mJ mol −1 K −2 and a Debye Temperature Θ D = 181 K. First principles, correlated-band electronic structure calculations suggest that the neptunium magnetic moment in NpPt 2 In 7 is localized and that a quasi-two-dimensional antiferromagnetic structure could result from the competition of very weak interlayer interactions leading to very anisotropic properties.

The low-temperature heat capacity of (U 1-y ,Am y )O 2− x solid solution with y = 0.0811 and 0.2005 and x = 0.01–0.03 was determined from a minimum of 12.52 K up to 297.1 K and from 9.77 K up to 302.3 K, respectively, using hybrid adiabatic relaxation calorimtry. The low temperature heat capacity results of the investigated system revealed the absence of the magnetic transition specific for UO 2 in the temperature region of 30 K. Since there are no experimental data available for AmO 2 in this temperature region, the results obtained for the intermediate compositions are validated based on the experimental data of UO 2 end-member and the low-temperature heat capacity computation of AmO 2 . In the measured temperature interval, excess heat capacity was observed for the two investigated intermediate compositions, which is concluded to be dominated by self-radiation effects at very low temperature.

The enthalpy of formation at 298.15 K and low temperature heat capacity of Cs3Na(MoO4)2 have been measured for the first time in this work using solution calorimetry and thermal-relaxation calorimetry in the temperature range T = (1.9–299.6) K, respectively. The solution calorimetry measurements, performed in 2 M HNO3 solution, have yielded an enthalpy equal to ΔrHmΔrHm(298.15 K) = (6.79 ±± 1.72) kJ··mol−1 for the reaction:3/2Cs2MoO4(cr)+1/2Na2MoO4(cr)=Cs3Na(MoO4)2(cr)3/2Cs2MoO4(cr)+1/2Na2MoO4(cr)=Cs3Na(MoO4)2(cr)Combining with the enthalpies of formation of Cs2MoO4(cr) and Na2MoO4(cr), also determined in this work in 0.1 M CsOH and 0.1 M NaOH solutions, respectively, the standard enthalpy of formation of Cs3Na(MoO4)2 at 298.15 K has been determined as View the MathML sourceΔfHmo(Cs3Na(MoO4)2, cr, 298.15 K) = −(2998.5 ±± 3.0) kJ··mol−1. The heat capacity and entropy values of Cs3Na(MoO4)2 at 298.15 K have been derived as View the MathML sourceCp,mo(Cs3Na(MoO4)2,cr,298.15K)=(296.3±3.3) J··K−1··mol−1 and View the MathML sourceSmo(Cs3Na(MoO4)2,cr,298.15K) (467.2±6.8) J··K−1··mol−1. Combining the newly determined thermodynamic functions, the Gibbs energy of formation of Cs3Na(MoO4)2 at 298.15 K has been derived as View the MathML sourceΔfGmo(Cs3Na(MoO4)2,cr,298.15K)=-(2784.6±3.4) kJ··mol−1. Finally, the enthalpies, entropies and Gibbs energies of formation of Cs3Na(MoO4)2 from its constituting binary and ternary oxides have been calculated.

Microchip capillary electrophoresis (MCE) with integrated electrodes to perform electrochemical (EC) sensing is a powerful tool for fundamental research and practical applications that are increasingly in demand. In this critical review, we discuss the main strategies developed over the last twenty years to design complete MCE-EC devices. First, we outline all the questions raised by the pioneering research groups regarding the coupling of these two techniques in microfluidic devices. Then, we present all the key-solutions, in the form of strategies, that our colleagues have cleverly elaborated to make these devices evolve into elaborate and relevant tools. These evolutions have mainly focused on the nature of the electrodes used, their configuration, the process of their fabrication, their integration and positioning in the microfluidic systems and their performance within the integrated devices. Particular attention is paid to the adequacy of the materials of the microsystems and the electrodes and to the resolution of the electrical interference between the electric fields necessary for the electrophoretic separation and the electrochemical detection. Finally, we describe significant examples of methodologies for the analysis of complex biological, food and environmental samples, highlighting the analytical improvements brought by these MCE-EC systems.

Investigations on the phase relation in the Pb-U-O ternary system have shown the formation of three lead uranium(VI) oxides: PbUO 4 , Pb 3 UO 6 , and Pb 3 U 11 O 36 . We present here the synthesis, thermal expansion, low- and high-temperature heat capacity, and thermal diffusivity of two representative phases (PbUO 4 and Pb 3 UO 6 uranates). Combining these results, a value for their thermal conductivity was derived and reported here for the first time.

The formation of organic thin layers on platinum microbands prepared by photolithography and sputtering techniques following the electrografting of a 4-azidobenzene diazonium salt was evaluated. The electrografting process was characterized by cyclic voltammetry in the presence of reversible redox probes. Further modification of the azide-modified platinum surfaces was achieved by the covalent attachment of ethynylferrocene via the copper(I)-catalyzed azide-alkyne cycloaddition-“click” reaction (CuAAC). Optimization of the electrografting method was performed based on the active ferrocene surface coverage reaching a maximum of 2.5 × 10−10 mol cm−2 after ten voltammetric scans. In addition, the modified microbands exhibited a high stability with a recovery of over 75% of the initial ferrocene response after 3 weeks of bench storage. This data supports the possibility of rapid and straightforward functionalization of platinum microbands for a range of analytical applications prior to their integration into microdevices. Keywords: Platinum microbands, Surface modification, Diazonium salt, Electrografting, Click reaction

A new low-cost reversible Glass-NOA®-PDMS microfluidic device was designed for the study of recovery yield of precious metals present in acid media mimicking leach liquors for long-term recycling objectives. It offers the unique advantage of allowing easy washing of the microchannel and renewal of the electrode surface by simply repositioning the microband electrodes which allows this type of device to have a relatively much longer lifespan than irreversibly closed ones. It consists in a re-useable microchip with four graphite microbands electrodes, prepared by screen printing, to set-up an original amperometric device for both depletion and yield quantification. One upstream working electrode is devoted to the depletion of the metallic ions through their electrolysis by electrodeposition while the second downstream working microelectrode is used as real-time detection electrode to evaluate the depletion efficiency. The dimensions of the depletion electrode and of the channel were optimized thanks to numerical simulations for a given range of flow velocities. First, the performances of the device were assessed experimentally according to flow rate and applied potential under continuous flow, and then compared to theoretical predictions using an electrochemical probe, ferrocenemethanol. The proof of concept was then demonstrated for precious metal, by electroreduction of Pd(II) and Au(III) from acidic leach liquors under continuous flow, with a depletion yield of up to 89% and 71% respectively.

A thermodynamic assessment of the KF-ThF4 binary system using the CALPHAD method is presented, where the liquid solution is described by the modified quasichemical formalism in the quadruplet approximation. The optimization of the phase diagram is based on experimental data reported in the literature and newly measured X-ray diffraction and differential scanning calorimetry data, which have allowed to solve discrepancies between past assessments. The low temperature heat capacity of α-K2ThF6 has also been measured using thermal relaxation calorimetry; from these data the heat capacity and standard entropy values have been derived at 298.15 K: Cp,mo(K2ThF6,cr,298.15K)=(193.2±3.9) J·K-1·mol-1 and Smo(K2ThF6,cr,298.15K)=(256.9±4.8) J·K-1·mol-1. Taking existing assessments of the relevant binaries, the new optimization is extrapolated to the ternary systems LiF-KF-ThF4 and NaF-KF-ThF4 using an asymmetric Kohler/Toop formalism. The standard enthalpy of formation and standard entropy of KNaThF6 are re-calculated from published e.m.f data, and included in the assessment of the ternary system. A calculated projection of the NaF-KF-ThF4 system at 300 K and the optimized liquidus projections of both systems are compared to published phase equilibrium data at room temperature and along the LiF-LiThF5 and NaF-KThF5 pseudobinaries, with good agreement.

Graphite rods were modified by substituted aryldiazonium salts allowing subsequent laccase immobilisation and direct electron transfer at the cathode. Two covalent enzyme immobilisation methods were performed with carboxy and amino substituted grafted groups, either via the formation of an amide bond or a Schiff base between the glycosidic groups of the enzyme and the amino groups on the electrode surface, respectively. Laccase adsorption efficiency was consistently compared to the covalent attachment method on the same carbon surface, showing that the latter method led to a higher immobilisation yield when the electrode surface was functionalised with carboxylic groups, as shown from both laccase activity measurement towards an organic reducing substrate, ABTS, and quantitative XPS analysis. Both analytical methods led to similar laccase surface coverage estimations. From activity measurements, when laccase was covalently immobilised on the electrode functionalised with carboxylic groups, the surface coverage was found to be 43 ± 2% whereas it was only 10 ± 3% when laccase was adsorbed. Biocatalysed dioxygen reduction current was also higher in the case of covalent immobilisation. For the first time, oxidised laccase performances were compared to unmodified laccase, showing significant improved efficiency when using oxidised laccase: the current obtained with oxidised laccase was 141 ± 37 μA cm− 2 compared to 28 ± 6 μA cm− 2 for unmodified laccase after covalent immobilisation of the enzyme on a graphite electrode functionalised with carboxylic groups.

The low-temperature heat capacity of the (Th1−y,Puy)O2 solid solution with y=0.03, 0.08, 0.30, 0.54 and 0.85 was determined from 4 K up to about 300 K with a PPMS instrument using the hybrid adiabatic relaxation method. In addition, the heat capacity of 239PuO2 end member was also measured and compared with available literature data for 242PuO2, observing an indistinguishable match. The obtained heat capacity values of the intermediate compositions are greater than the data obtained from Neumann–Kopp's molar additivity rule based on the ThO2 and PuO2 end-members, and a substantial excess capacity is observed for all intermediate compositions, particularly at the lowest temperatures.

The heat capacity of α-Na2NpO4 has been measured for the first time in the temperature range 2.1–301 K using a Quantum Design PPMS (Physical Property Measurement System) calorimeter. The heat capacity and entropy values at 298.15 K have been derived as C p , m o ( α -Na2NpO4, cr, 298.15 K) = (151.9 ± 4.6) J K−1 mol−1 and S m o ( α -Na2NpO4, cr, 298.15 K) = (178.3 ± 4.3) J K−1 mol−1, respectively. The standard entropy of α-Na2NpO4 follows the trend shown by the isostructural compound α-Na2UO4 and the alkaline earth uranates MgUO4, SrUO4, BaUO4, and Cs2UO4. When combined with the entropies of the constituent elements, these data yield a standard entropy of formation at 298.15 K as Δ f S m o ( α -Na2NpO4, cr, 298.15 K) = − (385.1 ± 4.3) J K−1 mol−1. Using the enthalpy of formation tabulated in the literature, the standard Gibbs energy of formation was calculated at 298.15 K as Δ f G m o ( α -Na2NpO4, cr, 298.15 K) =(−1649.0 ± 5.8) kJ mol−1.

Sperm and embryos cryopreservation is a commonly applied technique for several years. Recently authorized in France, vitrification tends to replace gradually the conventional technique of slow freezing, so upsetting the practices in the management of patients. It allows from now on the cryopreservation of oocytes and opens new perspectives in egg donation either still in fertility preservation. This review thus attempted to examine the contribution of vitrification in the freezing of oocytes and human embryos at various stages of development. If obviously vitrification appears as the current method of choice for the cryopreservation of oocytes as well as blastocysts, the results are less cut as regards embryos to early stages. No increase in adverse obstetric and perinatal outcomes in children conceived from vitrified oocytes or embryos is noted in the literature

Nitric oxide (NO) is known to be implicated in various renal diseases induced by lead poisoning and recent works have shown the effect of some antioxidants in reducing the toxic effects of lead. Melatonin is attractive for its direct and indirect antioxidant effects; furthermore it is naturally produced in mammalians, including humans. Recently, it has been shown that melatonin attenuates the toxic effects of sub-acute lead intoxication in kidneys without altering NO metabolites concentration. This work demonstrates the use of nickel tetrasulfonated phthalocyanine/polyphenol-modified ultramicroelectrodes to monitor in vivo and in situ changes of NO within rat kidneys. NO itself was detected directly and in real-time inside the kidney of lead and melatonin treated rats after induction by L-arginine. The results indicate that NO production decreases in lead treated rats, likewise in co-treated with melatonin rats. In addition, melatonin administration did not affect the production of NO respect to the control. By means of these experiments was verified that melatonin does not alters NO production in kidneys during sub-acute lead intoxication.

International audience; We report here the proof of concept of the use of new assembled arrays of ultramicroelectrodes (UMEs) for the simultaneous and dynamic sensing of reactive nitrogen species such as nitric oxide (NO) and peroxynitrite (ONOO-, so-called PUN) released by cultured cells. These devices fill the need to study the key roles of these two reactive nitrogen species where a chemical imbalance is implicated in several pathologies and physiological disorders. Arrays containing over 2400 gold UMES were designed in such a way to increase sensitivity and allow detection of low concentrations of the target analytes in vivo. These disposable platforms are then integrated within cell culture wells and plates, resulting in an easy-to-handle tool for cellular biology. They were successfully used to detect in real time PUN formed in situ upon the reaction of NO released from a NO donor molecule ((Z)-1-[N-(2-aminoepropyl)-N-(2-ammoniopropyl)amino]-diazen-1-ium-1,2-diolate) and superoxide (O-2(-)) released by PMA (phorbol-12-myristate-13-acetate)-induced HL60 cells. (C) 2014 Elsevier Ltd. All rights reserved.

Prevalence of type II diabetes and cardiometabolic diseases is increasing worldwide and early identification of their complications could reduce healthcare costs. An early complication of diabetes is small fiber neuropathy that can be diagnosed through assessment of sweat dysfunction. In this context, the Sudoscan™ technology developed by Impeto Medical provides early diagnosis, rapid and non-invasive analysis of sudomotor functions. This technology is based on measurements of skin current density via the imposition of low amplitude voltages (4 to 1.5V) between electrodes applied to the skin and measuring the low current generated. These electrodes are sensitive to the composition of the sweat produced by the eccrine glands when stimulated. To optimize the electrode materials and the diagnosis, a better insight into the origin of the electrochemical signals is needed by mimicking the in vivo results through the use of a model electrochemical cell reproducing physiological sweat conditions. In this paper, the electrode surface was modified with polymeric membranes to mimic the role of the filter of the skin and to get similar results to those obtained by Sudoscan™. Then, the composition of the electrolyte was changed by optimizing its viscosity to reduce the flow of Cl − ions to the electrode surface. The electrochemical behavior of the electrodes, measured in terms of current-voltage studied in artificial sweat, were compared to those of the Sudoscan™ technology.

Oxidative stress has recently became one of the most important and negative factors that affect favourable human reproduction and therefore plays a crucial role in the successful outcome rates on artificial reproduction techniques (ARTs). The effects of oxidative stress are strengthened in an ART setting since there are more sources of reactive oxygen and nitrogen species (ROS/RNS) generation and a more vulnerable physiological defence mechanism. Culture media, for this reason, have improved in their composition and are becoming more complex, above everything, in their antioxidant power to face ROS/RNS generation. In this work, we suggest the use of electrochemical (bio)sensors to evaluate the presence and evolution of nitric oxide (NO) and superoxide anion (O2−), in a commercial culture medium compared to conventional phosphate buffer solution. The electrochemical monitoring of NO was followed by the real-time NO-release from a commercially available NO donor (diazeniumdiolate) under aerobic conditions in a surface-modified screen-printed linear platinum array electrode. Concurrently, superoxide anion detection was evaluated at a surface-modified screen-printed linear gold electrode by the real-time and in situ generation of O2−. The performances of both arrayed sensors were compared to those obtained at single modified ultramicroelectrodes. We deepen the study of the intrinsic and external interferents for the application of these electrochemical (bio)sensors in order to provide an oxidative stress index during embryo development. M. Gómez-Mingot gratefully acklowledges the Universidad de Alicante for the PhD fellowship that allowed her to visit the laboratory in the group of Dr. Bedioui in Paris. Financial support from the Spanish Ministry of Science and Technology (“Project CTQ2010-18570”) and the University of Alicante are gratefully acknowledged.

We present here an overview of the properties of transuranium superconductors, but also of the (non-superconducting) transuranium analogues of uranium superconductors. We briefly review superconductivity in actinide elements and uranium compounds and focus in particular on the PuTX 5 ( T = Co , Rh ; X = Ga , In ) series, the largest superconducting system in actinides and NpPd 5 Al 2 , the so far unique neptunium superconductor. The effects of chemical substitution, ageing and pressure on the properties of transuranium superconductors are also discussed.

We report on the surface micropatterning of conductive surfaces via the electrochemical triggering of a click reaction, the copper(I) catalyzed azide–alkyne cycloaddition reaction (CuAAC) by SECM via a two-step approach: (i) functionalization on the entire surface with azido-aryl groups by using the diazonium approach followed by (ii) the covalent linkage of alkyne-bearing ferrocene by CuAAC within a local area by SECM. More precisely, the click reaction was triggered by Cu(I) catalyst generation for 30 min at the SECM tip positioned ≈10 μm above the azido-aryl modified surface. The dimension of the spot obtained under these conditions was ≈75 μm. The electrochemical imaging by SECM of the ultra thin area locally clicked with ferrocene moieties was made thanks to the electrocatalytic properties of the ferrocene modified surface towards ferrocyanide electrooxidation. This local clicking procedure opens the gate to further controlled functionalization of restricted small substrates. Keywords: Click reaction, Azido-aryl diazonium, SECM, Local modification

We report in this study on the simultaneous conductance and cyclic voltammetry measurements during the potentiodynamic electropolymerization of PPy films, incorporating in the polymeric matrix, first, multi-walled carbon nanotubes (MWCNTs), second, cobalt phthalocyanine (CoPc) and finally both compounds simultaneously are herein presented. Four different MWCNTs were studied (diameter 30 ± 15 nm and 15 ± 5 nm, both with lengths of 1–5 μm and 5–20 μm). The results indicate that the conductance and compatibility of PPy/MWCNT composites is ruled by the quantity of exposed anionic groups on the MWCNT surface. Those with the widest diameter have the best performances and also have the largest quantity of anionic groups (carboxylic acids). After incorporation of CoPc, the composite material showed enhanced electrical properties that could be useful in the future as a sensor material in the detection of redox species.