Kinematics of charge transfer: Ar^++H2

This is the publisher's version, also available electronically from http://scitation.aip.org/content/aip/journal/jcp/67/6/10.1063/1.435181.Product angular and velocity vector distributions have been measured in a crossed beam experiment for the charge transfer process Ar++H2→Ar+H2 + at relative collision energies of 0.13, 0.48, and 3.44 eV. Charge transfer was found to occur by two distinct mechanisms: (1) a simple electron‐jump mechanism which preserves the quasirectilinear trajectories of the colliding species and which selectively produces H2 + in the vibrational state most nearly resonant with the reactant ion, and (2) an intimate‐collision mechanism which results in large‐angle scattering and which produces H2 + in a broad range of vibrational states

An iron-based beverage, HydroFerrate fluid (MRN-100), alleviates oxidative stress in murine lymphocytes in vitro

BackgroundSeveral studies have examined the correlation between iron oxidation and H2O2 degradation. The present study was carried out to examine the protective effects of MRN-100 against stress-induced apoptosis in murine splenic cells in vitro. MRN-100, or HydroFerrate fluid, is an iron-based beverage composed of bivalent and trivalent ferrates.MethodsSplenic lymphocytes from mice were cultured in the presence or absence of MRN-100 for 2 hrs and were subsequently exposed to hydrogen peroxide (H2O2) at a concentration of 25 μM for 14 hrs. Percent cell death was examined by flow cytometry and trypan blue exclusion. The effect of MRN-100 on Bcl-2 and Bax protein levels was determined by Western blot.ResultsResults show, as expected, that culture of splenic cells with H2O2 alone results in a significant increase in cell death (apoptosis) as compared to control (CM) cells. In contrast, pre-treatment of cells with MRN-100 followed by H2O2 treatment results in significantly reduced levels of apoptosis. In addition, MRN-100 partially prevents H2O2-induced down-regulation of the anti-apoptotic molecule Bcl-2 and upregulation of the pro-apoptotic molecule Bax.ConclusionOur findings suggest that MRN-100 may offer a protective effect against oxidative stress-induced apoptosis in lymphocytes

Geochemical Modelling as a Tool for Actinide Speciation during Anoxing Leaching Processes of Nuclear Fuel.

Abstract not availableJRC.E-Institute for Transuranium Elements (Karlsruhe

A Complete and the Most Liberal Semantics for Converging OR Gateways in Sound Processes

Although the semantics of converging OR gateways (also known as OR-joins) in business processes is far from trivial, they are frequently used. In this paper, we describe a general definition for soundness of processes guaranteeing the absence of deadlocks and no lack of synchronization for each possible OR-join semantics. Then, we derive a criterion — completeness — to evaluate existing approaches of OR-join semantics. As a result, no currently existing OR-join semantics is complete; therefore, there are actually correct processes being not successfully executable. For that, we provide our own approach based on a traditional relation of compiler construction; and we show that this approach is complete and can be called the most liberal possible

Control-Flow-Based Methods to Support the Development of Sound Workflows

Workflows describe sequences of tasks to achieve goals. These sequences can contain decisions, loops, and parallelisations and are, therefore, similar to computer programs. Experts in the domain of workflow application usually design these workflows. However, these experts are rarely IT experts. For this reason, after automation by a computer, workflows can exhibit undesired behaviors. Such behaviors can be expensive and dangerous and should be avoided. The notion of soundness describes the absence of the undesired behaviors of deadlocks and abundances. The state of the art in workflow verification can detect such behaviors, but gives no indication of causes, does not provide detailed diagnostic information, or is slow. This article introducēs two new compiler-based techniques to find causes of deadlocks and abundances. These techniques provide detailed diagnostic information and have a cubic asymptotic complexity of runtime. Their efficiency and quality is evaluated using a benchmark of over thousand real-world workflows together with two leading state-of-the-art approaches

A kinetic study of UO2 dissolution and H2O2 stability in the presence of groundwater ions.

Current reactors spent nuclear UO2 fuel, that will probably enter geologic formations for disposal, is assumed to get into contact with groundwater of a repository earliest after several thousands of years. After this time, its alpha activity will be still high enough to induce a process of water radiolysis that leads to production of oxidants and, probably, to the oxidative dissolution of the material, that could start a mobilisation of radiotoxic nuclides. The main oxidant produced during this process would be hydrogen peroxide (H2O2), which is thermodynamically unstable and can decompose during reactions with certain groundwater ions. Information on the stability of H2O2 is therefore important for assessing the behaviour of the material in the repository. We investigated the stability of H2O2 and the correlated dissolution of U from UO2 as a function of the concentration of H2O2 and of the groundwater ions carbonate, sulphate, and silicate. Decomposition of H2O2 was measured in the presence and absence Of UO2(cr). We monitored the concentrations of H2O2, U-diss, groundwater ions, O-2 (diss), and the pH in aqueous solution under Ar atmosphere. The lowest stabilities (in average) for H2O2 were found in carbonate solutions. When comparing the effect of carbonate systems containing UO2(cr) to carbonate solutions without a solid phase, we found that in some of the homogeneous tests H2O2 was consumed faster. This effect was not observed with the other groundwater ions. Also, U dissolution rates were significantly lower in the carbonate experiments than in those with sulphate or silicate. The results suggest that a radical-controlled mechanism (similar to the Halpern - Smith-mechanism of dissolved U(IV) oxidation) takes place at the UO2 surface during dissolution. The hypothesis is supported by ESR measurements on hydroxyl radical scavenging by the carbonate ion