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Anoxic corrosion processes impacting carbon steel samples for both intimate and imperfect metal/ low-pH bentonitic cement grout (BCG) contacts were studied at 80 °C. SEM, XRD and µ-Raman spectroscopy analyses supported by geochemical modelling allowed a full characterization of the corrosion mechanism. Steel in direct contact with BCG suffered from localized corrosion (pits measuring up to 160 µm in depth after 150 days of exposure) principally triggered by the presence of HS-. Depending on silicate and sulphide ingress from the BCG towards the interface, neoformed magnetite may be converted to iron silicates and/or iron sulphides. • XRD, µ-Raman, SEM-EDX analysis combined with geochemical modelling. • Sulphides from bentonitic cement-grout induced localized corrosion. • Presence of pits measuring up to 160 µm (150 days of interaction). • Transformation of magnetite into Fe-silicates and Fe sulphides. [ABSTRACT FROM AUTHOR]

This modelling study investigated the physicochemical and kinetic controls of the mineralogical evolutions of cementitious materials subject to accelerated atmospheric carbonation. Simulations are based on published experimental results on two samples, a hydrated C 3 S and a C-S-H paste, carbonated for 1 year at 55 % RH at 3 % CO 2. For the C 3 S paste, reactive transport simulations accurately reproduced the mineralogical observations at different time intervals. However, for the C-S-H paste, in which significant cracks appeared, basis simulations could not reproduce the long-term carbonation extent. 2D simulations suggested that potential preexisting cracks could not fully explain the seemingly increasing carbonation rates. A final simulation using a simplified description of the crack appearance during carbonation gave the most accurate representation of the experimental results (degradation depths, mineralogy evolution). This demonstrates that, to accurately estimate the durability of cementitious materials subject to carbonation under dry conditions, coupled geochemical-mechanical descriptions are required. [ABSTRACT FROM AUTHOR]

Abstract: This study investigates thermodynamics and kinetics of water–rock interactions in a carbonate aquifer at the watershed scale. A reactive transport model is applied to the unconfined chalk aquifer of the Champagne Mounts (France), by considering both the chalk matrix and the interconnected fracture network. Major element concentrations and main chemical parameters calculated in groundwater and their evolution along flow lines are in fair agreement with field data. A relative homogeneity of the aquifer baseline chemistry is rapidly reached in terms of pH, alkalinity and Ca concentration since calcite equilibrium is achieved over the first metres of the vadose zone. However, incongruent chalk dissolution slowly releases Ba, Mg and Sr in groundwater. Introducing dilution effect by rainwater infiltration and a local occurrence of dolomite improves the agreement between modelling and field data. The dissolution of illite and opal-CT, controlling K and SiO2 concentrations in the model, can be approximately tackled by classical kinetic rate laws, but not the incongruent chalk dissolution. An apparent kinetic rate has therefore been fitted on field data by inverse modelling: 1.5×10−5 molchalk L −1wateryear −1. Sensitivity analysis indicates that the CO2 partial pressure of the unsaturated zone is a critical parameter for modelling the baseline chemistry over the whole chalk aquifer. [Copyright &y& Elsevier]

The interactions between cement and a clayey host-rock of an underground repository for intermediate-level radioactive waste are studied with the reactive transport code HYTEC for supporting performance assessment. Care is taken in using relevant time scales (100,000 years) and dimensions. Based on a literature review, three hypotheses are considered with respect to the mineralogical composition of the claystone and the neo-formed phases. In the long term, the pH is buffered for all hypotheses and important mineral transformations occur both in cement and the host-rock. The destruction of the primary minerals is localized close to the cement/claystone interface and is characterized by the precipitation of secondary phases with retention properties (illite, zeolite). However, beyond the zone of intense mineral transformations, the pore water chemistry is also disturbed over a dozen meters due to an attenuated but continuous flux of hydroxyl, potassium and calcium ions. Four interdependent mechanisms control the profile in the whole system: diffusion of the alkaline plume, mineralogical buffering, ion exchange and clogging of the pore space at the cement/claystone interface. The migration of a selected group of radionuclides (Cs, Ra, Tc and U) is explicitly integrated in the simulations of the strongly coupled system. Theoretical profiles of distribution coefficient (Kd) and solubility limit values are derived from the simulations, and their sensitivity with respect to the system evolution is estimated. [Copyright &y& Elsevier]

Oxidative dissolution of uranium dioxide (UO2) and the subsequent migration of uranium in a subsurface environment and an underground waste disposal have been simulated with reactive transport models. In these systems, hydrogeological and chemical processes are closely entangled and their interdependency has been analyzed in detail, notably with respect to redox reactions, kinetics of mineralogical evolution and hydrodynamic migration of species of interest.Different codes, where among CASTEM, CHEMTRAP and HYTEC, have been used as an intercomparison and verification exercise. Although the agreement between codes is satisfactory, it is shown that the discretization method of the transport equation (i.e. finite elements (FE) versus mixed-hybrid FE and finite differences) and the sequential coupling scheme may lead to systematic discrepancies. [Copyright &y& Elsevier]

Abstract: Mineralogical and petrographical investigations of a borehole sealed by concrete (“engineered analogue” of concrete/clay interactions) overcored at the Tournemire site offer the possibility to perform reactive transport modeling over a timescale of 15 years, which is significantly longer than standard durations of laboratory experiments. The HYTEC code was used to simulate mineralogical evolutions in the Tournemire argillite matrix and along small fractures, as well as in concrete, assuming either thermodynamic equilibrium approach or kinetic control coupled to diffusive transfer. The mineralogical profiles calculated in thermodynamic equilibrium and with kinetics are very similar in the concrete. In contrast, kinetics of dissolution and precipitation reactions is found to be necessary for a better reproduction of the experimental observations in the argillite samples compared to thermodynamic equilibrium calculations, in particular with respect to the extent of the alkaline perturbation. The major effects observed when considering kinetics in the calculations are to smooth the sharpness and intensity of the mineralogical transformation fronts, these fronts being predicted to occur deeper inside the argillite matrix (<1cm) and the fractures (⩽2cm), as well as to lessen clogging of pores within the argillite. At 15°C, the secondary mineral sequence simulated from the concrete to the argillite is: CSH/ettringite/carbonates at the concrete/argillite interface, followed by a zone of neoformation of clay-like phases and calcite, and a last zone with precipitation of calcite. Main discrepancies between the modeling results and the experimental observations are the precipitation of muscovite instead of K-feldspar and the neoformation of zeolites. Calculations also correctly predict that carbonates form at the concrete/argillite interface, which most probably result from concrete alteration and follow Ostwald’s step rule of mineral precipitation with a predominance of metastable vaterite over calcite. [Copyright &y& Elsevier]

Two semi-passive treatment systems for iron (Fe) and arsenic (As) removal in AMD were installed and monitored in-situ for more than a year. These technologies were designed to treat the As-enriched AMD (≈ 1 g/L Fe(II) and 100 mg/L As(III)) of the ancient Carnoulès mine. The treatment was based on biological Fe and As oxidation by indigenous bacteria, and subsequent immobilization of As by ferric hydroxysulfates. Forced aeration and wood/pozzolana or plastic support were used for biofilm attachment. The system performance ranged from 86 to 98% for Fe oxidation, 30 to 60% for Fe removal, and 50 to 80% for As removal at a hydraulic retention time of 9 h. No significant difference were measured between the two biofilm supports. The wood/pozzolana support had a shorter delay for performance recovery after interruptions. Iron oxidation rates were similar to those obtained in the Carnoulès AMD stream and laboratory bioreactor, while As oxidation seemed to be enhanced. The sludge accumulated between 39 and 91 mg/g of As, mainly in the As(V) oxidation state; jarosite and amorphous ferric hydroxysulfate phases were the main Fe and As scavengers. Challenging environmental conditions during the long monitoring period confirm the robustness of the treatment units. The data will be useful in designing future full-scale treatment systems adapted to As-rich AMD. [ABSTRACT FROM AUTHOR]

Abstract: The alteration of simplified synthetic glass, representative of the French reference nuclear glass R7T7, in presence of hydromagnesite has been experimentally investigated and modeled. Magnesium in solution is known to potentially enhance glass alteration; nuclear glass clayed host rocks contain magnesium and can dissolve to maintain the concentration of magnesium in solution. For modeling purposes, it was suitable to study a simple system. Hydromagnesite was therefore chosen as a simple model mineral in order to check the influence of an Mg-rich mineral on glass alteration. Since the models use thermodynamic and kinetic parameters measured in pure water and pH-buffered solutions, changing the solution composition or adding minerals is a key step towards the validation of the modeling assumptions before using the model for predictive purposes. Experiments revealed that glass alteration is enhanced in presence of hydromagnesite. Modeling was performed using the GRAAL model implemented within the CHESS/HYTEC reactive transport code. Modeling proved useful both for explaining the mechanisms involved and quantifying the impact on glass alteration: Mg coming from hydromagnesite dissolution reacts with Si provided by the glass in order to form magnesium silicates. This reaction decreases the pH down to neutral conditions where magnesium silicates are more soluble than at the natural alkali pH imposed by glass or hydromagnesite dissolution. The driving force of the magnesium silicate precipitation is eventually the interdiffusion of alkali within the altered amorphous glass layer as this mechanism consumes protons. The model’s ability to describe the concentrations of elements in solution and formed solids whatever the glass/hydromagnesite ratio strongly supports the basic modeling hypothesis. [Copyright &y& Elsevier]

• Fractional Release Rates of two samples (in-vessel and ex-vessel) were obtained. • Fraction of Inventory in Aqueous Phase of Mo, Ba, Sr, Rh, La, etc. was obtained. • Geochemical modeling was performed to better understand experimental results. On 11 March 2011, the Great East Japan Earthquake occurred and caused a severe nuclear accident at the Fukushima Daiichi Nuclear Power Station (1F). A policy for corium debris retrieval will be decided in the near future. To this end, debris management after removal from reactors must be optimized. From the viewpoint of cost and waiting for definitive solutions, interim or long-term underwater storage is one of the considered options after debris removal. Leaching data on the long term behavior of debris in water are therefore needed before debris removal. In addition, it is important to understand potential differences in leaching behaviors between debris and Spent Fuel (SF) to get comparative elements. For these reasons, simulated in-vessel and ex-vessel corium debris, fabricated in the Colima experimental facility set up in the PLINIUS platform at CEA Cadarache, were selected and leaching experiments were carried out under oxidizing conditions. In parallel, geochemical modeling was performed to better understand the experimental concentrations, pH evolutions and secondary phase's formation. Finally, the Fractional Release Rates of the (U, Zr)O 2 matrix for the two kinds of samples (in-vessel and ex-vessel) were found to be close to or one order of magnitude lower than that of SF under oxidizing conditions (from 10−6 to 10−7 per day) but the release processes are different. Indeed, the Fraction of Inventory in Aqueous Phase of Mo, Ba, Sr, Rh, La, Nd, Ce and Y tended to be higher than that of uranium and zirconium in this study whatever the element considered. The release of simulating PFs, including low volatile element like trivalent rare earths, does not appear to be fully controlled by that of the (U, Zr)O 2 matrix from a macroscopic and average point of view. The FPs could be partially located outside the (U, Zr)O 2 solid solution as a function of the corium history (quenching rate and thermal history, chemical interactions...). The location of inventories and their chemical forms are not very well known moreover uncertainties related to heterogeneity are important and may also impact the calculation of the global released fractions over time. For the ex-vessel sample, releases into the solution of the main concrete elements (Si, Ca, Mg) seem well correlated and dissociated from the behavior of the (U, Zr)O 2 phase. Further studies are needed especially on real or prototypical corium approaching the conditions of the Fukushima accident. The study of simpler and model systems could also provide information on the reactivity of the (U, Zr)O 2 matrix. [ABSTRACT FROM AUTHOR]

Pre-eclampsia (PE) is strongly associated with heart failure (HF) later in life. During PE pregnancy, the left ventricle undergoes concentric remodeling which often persists after delivery. This aberrant remodeling can induce a molecular signature that can be evaluated in terms of microRNAs (miRNAs) and which may help to explain the associated increased risk of HF. For this review, we performed a literature search of PubMed (National Center for Biotechnology Information), identifying studies on miRNA expression in concentric remodeling and on miRNA expression in PE. The miRNA data were stratified based on origin (isolated from humans or animals and from tissue or the circulation) and both datasets compared in order to generate a list of miRNA expression patterns in concentric remodeling and in PE. The nine miRNAs identified in both concentric remodeling and PE-complicated pregnancy were: miR-1, miR-18, miR-21, miR-29b, miR-30, miR-125b, miR-181b, miR-195 and miR-499-5p. We found five of these miRNAs (miR-18, miR-21, miR-125b, miR-195 and miR-499-5p) to be upregulated in both PE pregnancy and cardiac remodeling and two (miR-1 and miR-30) to be downregulated in both; the remaining two miRNAs (miR-29b and miR-181b) showed upregulation during PE but downregulation in cardiac remodeling. This innovative approach may be a step towards finding relevant biomarkers for complicated pregnancy and elucidating their relationship with remote cardiovascular disease. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd. [ABSTRACT FROM AUTHOR]

ABSTRACT Objectives Pre-eclampsia (PE) is associated with both postpartum structural asymptomatic heart disease (i.e. heart failure Stage B (HF-B)) and conventional cardiovascular (CV) risk factors. We aimed to evaluate the extent to which PE, adjusted for conventional CV risk factors, is associated independently with asymptomatic cardiac abnormalities postpartum. Methods In this cross-sectional cohort study, 107 formerly pre-eclamptic women and 41 women with uneventful previous pregnancy (controls) were invited for CV risk assessment 4-10 years postpartum. This included cardiac ultrasound, blood pressure (BP) measurement and evaluation of metabolic syndrome determinants. Asymptomatic structural and functional cardiac abnormalities were classified as HF-B, according to the American Heart Association guidelines. Prehypertension was defined as systolic BP of 120-139 mmHg and/or diastolic BP of 80-89 mmHg. Univariate and multivariate regression analyses were performed to calculate associations of PE and conventional risk factors with HF-B. Results The prevalence of asymptomatic HF-B was approximately 3.5-fold higher in the PE group compared with controls (25% vs 7%, P < 0.01); 67% of this group had concentric remodeling and 22% had mildly impaired ejection fraction. After adjustment for postpartum interval, hypertension and high-density lipoprotein, PE was significantly associated with HF-B (adjusted odds ratio, 4.4 (95% CI, 1.0-19.1)). Moreover, in the formerly pre-eclamptic group, prehypertension was associated significantly with HF-B (odds ratio, 4.3 (95% CI, 1.4-12.7)), while metabolic syndrome determinants were not. Conclusion PE is associated with a four-fold increased female-specific risk of asymptomatic cardiac abnormalities. Prehypertension apparently increases this risk significantly, while metabolic syndrome determinants do not. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd. [ABSTRACT FROM AUTHOR]

Abstract: This article summarizes the present state of knowledge concerning aqueous alteration of R7T7-type nuclear containment glasses, represented mainly by the inactive reference glass designated SON68. Based on this review, we propose to describe the glass alteration kinetics up to and including the final residual rate regime by means of a new mechanistic model known as GRAAL (glass reactivity with allowance for the alteration layer). Phenomenological analysis findings are reviewed for the various glass alteration regimes: interdiffusion, initial rate, rate drop, residual rate and, under very particular circumstances, resumption of alteration. These alteration regimes are associated with predominant mechanisms. Published work interpreting and modeling these mechanisms was examined in detail. There is a broad consensus on the general mechanisms of the initial rate and even the interdiffusion regime, whereas the mechanisms controlling the rate drop remain a subject of dispute not only with regard to nuclear glasses but also for the dissolution of silicate minerals. The reaction affinity responsible for the rate drop is expressed differently by different authors and depending on the underlying theories. The disagreement concerns the nature of the phase (glass or gel) or the activated complex controlling the rate drop, which in turn determines the elements that must be taken into account in the overall affinity term. Progress in recent years, especially in identifying the mechanisms responsible for the residual rate, has shed new light on these issues, allowing us to propose new theoretical foundations for modeling the different kinetic regimes of SON68 nuclear glass dissolution. The GRAAL model considers that water diffusion in the passivating reaction zone (the gel formed under saturation conditions) is a rate-limiting step in the overall glass dissolution kinetics. Moreover, this passivation zone is a soluble phase whose stability is directly dependent on the nature of the secondary phases likely to precipitate and on the solution renewal conditions. [Copyright &y& Elsevier]

Objective. We investigated whether in vivo closed–chest left ventricular pressure–volume measurements would yield similar values for LV hemodynamics compared with open–chest PV measurements under several anesthetics. Methods. The right common carotid of C57Bl/6 mice was cannulated with a combined pressure–conductance catheter and inserted retrogradely into the left ventricle in the closed–chest model. The open–chest model consisted of an abdominal approach involving the opening of the thoracic cavity by transverse opening of the diaphragm and ventricular catheterization by apical stab. Measurements were performed under urethane or pentobarbital intraperitoneal injection anesthesia. Results. Cardiac function in the open–chest model was characterized by larger ejection fraction and stroke volume with a leftward shift in ventricular volume compared to the closed–chest model. Further observed characteristics include low endsystolic pressure and arterial–ventricular coupling mismatch in the openchest model. Arrhythmias were not detected in either model. Conclusion. Murine cardiac function determination via open–chest or closed–chest protocols is sensitive, reproducible and comparable. The choice for open– or closed–chest pressure–volume measurements in mice depends on the aims of the study. [ABSTRACT FROM AUTHOR]

Objectives: Pre-eclampsia (PE) is associated with both postpartum structural asymptomatic heart disease (i.e. heart failure Stage B (HF-B)) and conventional cardiovascular (CV) risk factors. We aimed to evaluate the extent to which PE, adjusted for conventional CV risk factors, is associated independently with asymptomatic cardiac abnormalities postpartum.Methods: In this cross-sectional cohort study, 107 formerly pre-eclamptic women and 41 women with uneventful previous pregnancy (controls) were invited for CV risk assessment 4-10 years postpartum. This included cardiac ultrasound, blood pressure (BP) measurement and evaluation of metabolic syndrome determinants. Asymptomatic structural and functional cardiac abnormalities were classified as HF-B, according to the American Heart Association guidelines. Prehypertension was defined as systolic BP of 120-139 mmHg and/or diastolic BP of 80-89 mmHg. Univariate and multivariate regression analyses were performed to calculate associations of PE and conventional risk factors with HF-B.Results: The prevalence of asymptomatic HF-B was approximately 3.5-fold higher in the PE group compared with controls (25% vs 7%, P < 0.01); 67% of this group had concentric remodeling and 22% had mildly impaired ejection fraction. After adjustment for postpartum interval, hypertension and high-density lipoprotein, PE was significantly associated with HF-B (adjusted odds ratio, 4.4 (95% CI, 1.0-19.1)). Moreover, in the formerly pre-eclamptic group, prehypertension was associated significantly with HF-B (odds ratio, 4.3 (95% CI, 1.4-12.7)), while metabolic syndrome determinants were not.Conclusion: PE is associated with a four-fold increased female-specific risk of asymptomatic cardiac abnormalities. Prehypertension apparently increases this risk significantly, while metabolic syndrome determinants do not. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd. [ABSTRACT FROM AUTHOR]

Cardiac hypertrophy and consequent contractile dysfunction continue to burden Western society. Cardiomyocyte cyclic AMP (cAMP) and calcium are driving forces behind cardiomyocyte contraction. Distortion of their balance may induce HF, but specific therapies aiming at restoring physiological cAMP/calcium signaling are lacking.We recently identified microRNA-139 (miR-139) to be downregulated in failing human hearts. MiR-139 resides in the phosphodiesterase gene PDE2A and is predicted to target several phosphodiesterase messengers. In view of the central role of phosphodiesterases in controlling cardiac cAMP and calcium signaling, we hypothesized that miR-139 may affect HF progression by fine-tuning cAMP and calcium balances.Adeno-associated virus serotype 9 (AAV9), either empty control or expressing pre-miR-139, was administered to male C57Bl/6J mice. After allowing transgene expression for 3 weeks, mice were subjected to sham treatment or 4 weeks of pressure overload by subcutaneous Angiotensin II infusion (AngII, 2,5 mg/(kg·d). MiR-139 overexpression mildly aggravated HF development upon AngII with echocardiographically measured fractional shortening decreasing by 24±7% in AAV9-control AngII and by 46±5% in AAV9-pre-miR-139 AngII (n>11/group; p=0.14). In AAV9-control mice, AngII infusion led to concentric hypertrophy with an increased relative wall thickness (RWT) of 35±6%, whereas mice overexpressing miR-139 showed a rather eccentric form of hypertrophy with an increased RWT of 14±7% (p<0.05). The fraction of unphosphorylated cardiac troponin I (cTnI), a substrate of the cAMP dependent protein kinase A (PKA), tended to increase upon AngII infusion only in mice overexpressing miR-139 (n=4/group; p=0.11), indicating a reduced relaxation rate due to increased calcium sensitivity, a feature commonly observed in HF. Complimentary to these data, in vivo knockdown of mir-139 by cholesterol-tagged antagomiRs (20mg/kg) on three consecutive days before start of AngII infusion dampened the development of pressure overload-induced cardiac hypertrophy (increase in HW/TL: ctrl: 48±10%, n=4; antagomiR: 25±7%, n=7; p=0.16).In conclusion, cardiac downregulation of miR-139 upon pressure overload is a protective response to preserve cardiac function. AAV9-mediated overexpression of miR-139 promotes cardiac dilation and predisposes to HF. Upcoming experiments will aim at defining the molecular mechanism by which miR-139/phosphodiesterase signaling affects cardiac pathophysiology. [ABSTRACT FROM PUBLISHER]

An abstract of the study "NF-kappaB Regulates Adaptive Cardiac Hypertrophy," by A. Renger and colleagues is presented.