Iron‐Catalyzed Hydrosilylation of Esters

The first hydrosilylation of esters catalyzed by a well defined iron complex has been developed. Esters are converted to the corresponding alcohols at 100 °C, under solvent‐free conditions and visible light activation.     

Evaluation of bis-alkylamidoxime O-alkylsulfonates as orally available antimalarials

The main threat to controlling malaria is the emerging multidrug resistance of Plasmodium sp. parasites. Bis-alkylamidines were developed as a potential new chemotherapy that targets plasmodial phospholipid metabolism. Unfortunately, these compounds are not orally available. To solve this absorption issue, we investigated a prodrug strategy based on sulfonate derivatives of alkylamidoximes. A total of 25 sulfonates were synthesized as prodrug candidates of one bis-N-alkylamidine and of six N-substituted bis-C-alkylamidines. Their antimalarial activities were evaluated in vitro against P. falciparum and in vivo against P. vinckei in mice to define structure-activity relationships. Small alkyl substituents on the sulfonate group of both C-alkyl- and N-alkylamidines led to the best oral antimalarial activities; alkylsulfonate derivatives are chemically transformed into the corresponding alkylamidines.     

Discrete ply model of circular pull-through test of fasteners in laminates

In aeronautical structures, assemblies with thin laminates are becoming increasingly usual, especially for fuselage design. In these structures, out-of-plane loads can appear in bolted joints and can lead to progressive punching of the fastener’s head in the laminate resulting, in some cases, in a failure mode called pull-through [1]. This complex phenomenon, which occurs in assemblies, was studied firstly by using a simplified “circular” pull-through test method. Qualitative micrographic examinations showed damage very similar to that observed in impacted specimens. The research presented here extends the Discrete Ply Model Method (DPM) developed by Bouvet et al. [2] to this case. The finite elements model is based on a particular mesh taking ply orientations into account. Cohesive elements are placed at the interfaces between solid elements to represent matrix cracks and delamination, thus allowing the natural coupling between these two damage modes to be represented. The model shows good correlation with test results, in terms of load/displacement curve, and correct prediction of the damage map until failure, including the splitting phenomenon.     

A New Variant Selection Criterion for Twin Variants in Titanium Alloys (Part 2)

A new selection criterion to explain the activation of the twinning variant is proposed. This criterion is based on the calculation of the deformation energy to create a primary twin. The calculation takes into account the effect of the grain size using a Hall–Petch type relation. This criterion allows to obtain a very good prediction for the twin family selection and twin variant selection. The calculations are compared with the experimental results obtained on T40 (ASTM grade 2) deformed by Channel Die compression.     

Stabilizing vortices in interacting nano-objects: a chemical approach

We report a chemical method to prepare metallic Fe porous nanocubes. The presence of pores embedded inside the cubes was attested by electron tomography. Thanks to electronic holography and micromagnetic simulations, we show that the presence of these defects stabilizes the vortices in assembly of interacting cubes. These results open new perspectives toward magnetic vortex stabilization at relatively low cost for various applications (microelectronics, magnetic recording, or biological applications).     

Wet scrubbing intensification applied to hydrogen sulphide removal in waste water treatment plant

Hydrogen sulphide removal in a waste water treatment plant at semi‐industrial scale in a compact wet scrubber has been investigated. The gas residence time in the scrubber was reduced to 30 ms using a NaOCl caustic scrubbing solution. The contactor is composed of a wire mesh packing structure where liquid and gas flow co‐currently at high velocity (>12 m s⁻¹). H₂S removal percentages higher than 95% could be achieved whereas a moderate pressure drop was measured (<4000 Pa). Both the hydrodynamic and chemical conditions can influence the efficiency of the process. Correlations were developed to predict both the pressure drop and the H₂S removal efficiency at given operating conditions.     

Toughening and hardening in double-walled carbon nanotube/nanostructured magnesia composites

Dense double-walled carbon nanotube (DWCNT)/nanostructured MgO composites were prepared using an in situ route obviating any milling step for the synthesis of powders and consolidation by spark-plasma-sintering. An unambiguous increase in both toughness and microhardness is reported. The mechanisms of crack-bridging on an unprecedented scale, crack-deflection and DWCNT pullout have been evidenced. The very long DWCNTs, which appear to be mostly undamaged, are very homogeneously dispersed at the grain boundaries of the matrix, greatly inhibiting the grain growth during sintering. These results arise because the unique microstructure (low content of long DWCNTs, nanometric matrix grains and grain boundary cohesion) provides the appropriate scale of the reinforcement to make the material tough.