Carbon-sulfur bond strength in methanesulfinate and benzenesulfinate ligands directs decomposition of Np(v) and Pu(v) coordination complexes.

Gas-phase coordination complexes of actinyl(v) cations, AnO2+, provide a basis to assess fundamental aspects of actinide chemistry. Electrospray ionization of solutions containing an actinyl cation and sulfonate anion CH3SO2- or C6H5SO2- generated complexes [(AnVO2)(CH3SO2)2]- or [(AnVO2)(C6H5SO2)2]- where An = Np or Pu. Collision induced dissociation resulted in C-S bond cleavage for methanesulfinate to yield [(AnVO2)(CH3SO2)(SO2)]-, whereas hydrolytic ligand elimination occurred for benzenesulfinate to yield [(AnVO2)(C6H5SO2)(OH)]-. These different fragmentation pathways are attributed to a stronger C6H5-SO2-versus CH3-SO2- bond, which was confirmed for both the bare and coordinating sulfinate anions by energies computed using a relativistic multireference perturbative approach (XMS-CASPT2 with spin-orbit coupling). The results demonstrate shutting off a ligand fragmentation channel by increasing the strength of a particular bond, here a sulfinate C-S bond. The [(AnVO2)(CH3SO2)(SO2)]- complexes produced by CID spontaneously react with O2 to eliminate SO2, yielding [(AnO2)(CH3SO2)(O2)]-, a process previously reported for An = U and found here for An = Np and Pu. Computations confirm that the O2/SO2 displacement reactions should be exothermic or thermoneutral for all three An, as was experimentally established. The computations furthermore reveal that the products are superoxides [(AnVO2)(CH3SO2)(O2)]- for An = Np and Pu, but peroxide [(UVIO2)(CH3SO2)(O2)]-. Distinctive reduction of O2- to O22- concomitant with oxidation of U(v) to U(vi) reflects the relatively higher stability of hexavalent uranium versus neptunium and plutonium

Sur la forme de la boule unit\'{e} de la norme stable unidimensionnelle

For a Riemannian polyhedra, we study the geometry of the unit ball for the unidimensional stable norm (stable ball). In the case of a unidimensional Riemannian polyhedra (graph), we show that the stable ball is a polytope whose vertices are completely described by combinatorial properties of the graph. We study then the realizable forms as stable ball of Riemannan manifolds of dimension larger than three. For a Riemannian manifold $(M, g)$ fixed, we show that a broad class of polytopes can appear as stable ball of metrics in the conformal class of $g$. We use for that a polyhedral technique.Comment: 13 pages, in Frenc

Ultrametric probe of the spin-glass state in a field

We study the ultrametric structure of phase space of one-dimensional Ising spin glasses with random power-law interaction in an external random field. Although in zero field the model in both the mean-field and non-mean-field universality classes shows an ultrametric signature [Phys. Rev. Lett. 102, 037207 (2009)], when a field is applied ultrametricity seems only present in the mean-field regime. The results for the non-mean field case in an external field agree with data for spin glasses studied within the Migdal-Kadanoff approximation. Our results therefore suggest that the spin-glass state might be fragile to external fields below the upper critical dimension.Comment: 5 pages, 4 figures, 1 tabl

Is the fish-hook effect in hydrocyclones a real phenomenon?

Although the fish-hook effect has been reported by many for a very long time, scientists and practitioners alike share contradictory opinions about this phenomenon. While some believe that it is of physical origin, others opine that it is the result of measurement errors. This article investigates the possibility that the fish-hook effect could indeed be measurement error related. Since all the experimental errors are embedded in the raw size distribution measurements, the paper first lays down the steps that lead to estimation of the partition function and confidence bounds, which are seldom reported in hydrocyclone literature, from the errors associated with the experimental size distribution measurements. Using several data sets generated using a 100 mm diameter hydrocyclone operating under controlled dilute to dense regimes, careful analysis of the partition functions following the developed methodology yields unambiguous evidence that the fish-hook effect is a real physical phenomenon. An attempt is also made to reunite some of the major contradictory views behind the existence of the fish-hook based on sound statistical arguments

Exploring the Empirical Link Between Game Features, Player Motivation, and Game Behavior

This research-in-progress paper aims to propose a framework for predicting use continuance and subsequent in-game purchases in the context of online, free-to-play (F2P) mobile games. Using previous games research, we first propose Perceived Enjoyment (PE) and Use Continuance (UC) as the key predictors of Purchase Intention (PI). However, in order to extend the extant literature and generate practical insights for game developers into how to enhance the level of PE and UC generated by their games, we further explore the relations between a set of technical game features and their impact on users’ motivations for playing online F2P mobile games. Specifically, we look at three groups of features—connect, bonding, and share-in features—and test their effect on three key motivations underpinning perceived enjoyment in the context of digital game play, namely Achievement, Social, and Immersion motivations. Using data from a scenario-based questionnaire, our findings show that although all three motivations—Achievement, Social, and Immersion—result in greater enjoyment, and in turn, use continuance and purchase intention, only a single technical feature of the games—namely the share-in feature—triggers greater perceived immersion motivation. Implications for theory and practice are discussed

Attached cavitation in a laminar separation bubble

International audienceThe present study aims at studying the inception, the growth and the potential unsteady dynamics of attached vapour cavities in large laminar separation bubbles. A viscous silicon oil has been used in a venturi geometry in order to explore the flow for Reynolds numbers ranging from Re = 800 to Re = 2000. The results show that at low Reynolds number the attached sheets that are attributed to cavitation do not have any obvious dynamics and abruptly transit to supercavitation when lowering the cavitation number. For Re 1200, cavitating vortices are intermittently observed in the wake of the attached cavity with no clear period. Finally, a periodic shedding/shrinking of the main cavity is first observed for Re 1400, in a narrow range of cavitation numbers, together with a slower growth of the cavities when lowering the cavitation number. This regime is then present at higher Reynolds numbers, in a wider range of cavitation numbers

Structural basis for IL-33 recognition and its antagonism by the helminth effector protein HpARI2

IL-33 plays a significant role in inflammation, allergy, and host defence against parasitic helminths. The model gastrointestinal nematode Heligmosomoides polygyrus bakeri secretes the Alarmin Release Inhibitor HpARI2, an effector protein that suppresses protective immune responses and asthma in its host byinhibiting IL-33 signalling. Here we reveal the structure of HpARI2 bound to mouse IL-33. HpARI2 contains three CCP-like domains, and we show that it contacts IL-33 primarily through the second and third of these. A large loop which emerges from CCP3 directly contacts IL-33 and structural comparison showsthatthisoverlapswiththebindingsiteonIL-33foritsreceptor,ST2, preventing formation of a signalling complex. Truncations of HpARI2 which lack thelargeloopfromCCP3arenotabletoblockIL-33-mediatedsignallingin a cell-based assay and in an in vivo female mousemodelofasthma.Thisshows that direct competition between HpARI2 and ST2 is responsible for suppression of IL-33-dependent responses

Structural basis for IL-33 recognition and its antagonism by the helminth effector protein HpARI2

IL-33 plays a significant role in inflammation, allergy, and host defence against parasitic helminths. The model gastrointestinal nematode Heligmosomoides polygyrus bakeri secretes the Alarmin Release Inhibitor HpARI2, an effector protein that suppresses protective immune responses and asthma in its host byinhibiting IL-33 signalling. Here we reveal the structure of HpARI2 bound to mouse IL-33. HpARI2 contains three CCP-like domains, and we show that it contacts IL-33 primarily through the second and third of these. A large loop which emerges from CCP3 directly contacts IL-33 and structural comparison showsthatthisoverlapswiththebindingsiteonIL-33foritsreceptor,ST2, preventing formation of a signalling complex. Truncations of HpARI2 which lack thelargeloopfromCCP3arenotabletoblockIL-33-mediatedsignallingin a cell-based assay and in an in vivo female mousemodelofasthma.Thisshows that direct competition between HpARI2 and ST2 is responsible for suppression of IL-33-dependent responses

Structural basis for IL-33 recognition and its antagonism by the helminth effector protein HpARI2

IL-33 plays a significant role in inflammation, allergy, and host defence against parasitic helminths. The model gastrointestinal nematode Heligmosomoides polygyrus bakeri secretes the Alarmin Release Inhibitor HpARI2, an effector protein that suppresses protective immune responses and asthma in its host by inhibiting IL-33 signalling. Here we reveal the structure of HpARI2 bound to mouse IL-33. HpARI2 contains three CCP-like domains, and we show that it contacts IL-33 primarily through the second and third of these. A large loop which emerges from CCP3 directly contacts IL-33 and structural comparison shows that this overlaps with the binding site on IL-33 for its receptor, ST2, preventing formation of a signalling complex. Truncations of HpARI2 which lack the large loop from CCP3 are not able to block IL-33-mediated signalling in a cell-based assay and in an in vivo female mouse model of asthma. This shows that direct competition between HpARI2 and ST2 is responsible for suppression of IL-33-dependent responses