Hydrogenation of poly(myrcene) and poly(farnesene) using diimide reduction at ambient pressure

Ambient pressure chemical hydrogenation using p-toluene sulfonyl hydrazide (TSH) via thermal diimide formation (N₂H₂) permitted reduction of double bonds of poly(myrcene) (poly[Myr]) and poly(farnesene) (poly[Far]). Both pendent and backbone double bonds in poly(Myr) (M_n = 56 kg/mol) and poly(Far) (M_n = 62 kg/mol) synthesized by conventional free radical polymerization were hydrogenated to almost completion. Furthermore, TSH semi-batch addition efficiently hydrogenated double bonds, while avoiding undesired autohydrogenation of diimides that occurred in batch mode. Thermal stability improved for hydrogenated poly(Myr) and poly(Far), where temperature at 10% weight loss (T_10%) increased from 188 to 404°C for poly(Myr) and from 310 to 379°C for poly(Far). T_gs of poly(Myr) and poly(Far) also increased by about 10–25°C, indicating increased stiffness after hydrogenation. Finally, viscosities of poly(Myr) and poly(Far) were also increased after hydrogenation, and a greater increase was observed for poly(Myr) (by two orders of magnitude from 10² to 10⁴ Pa s) due to its M_n being much higher than its entanglement molecular weight. Poly(Far) viscosity only increased by 1.5 times after hydrogenation (~10⁴ Pa s), comparable to the poly(Myr) after hydrogenation, suggesting unsaturated poly(Far) was more entangled than unsaturated poly(Myr) because of its longer side chains.     

hcp‐Co Nanowires Grown on Metallic Foams as Catalysts for Fischer–Tropsch Synthesis

The Fischer–Tropsch synthesis (FTS) is a structure‐sensitive exothermic reaction that enables catalytic transformation of syngas to high quality liquid fuels. Now, monolithic cobalt‐based heterogeneous catalysts were elaborated through a wet chemistry approach that allows control over nanocrystal shape and crystallographic phase, while at the same time enables heat management. Copper and nickel foams have been employed as supports for the epitaxial growth of hcp‐Co nanowires directly from a solution containing a coordination compound of cobalt and stabilizing ligands. The Co/Cu_foam catalyst was tested for Fischer–Tropsch synthesis in a fixed‐bed reactor, showing stability and significantly superior activity and selectivity towards C5+ compared to a Co/SiO₂‐Al₂O₃ reference catalyst under the same conditions.     

NIR‐to‐NIR Two‐Photon Scanning Laser Microscopy Imaging of Single Nanoparticles Doped by YbIII Complexes

The photophysical and nonlinear optical properties of water‐soluble chromophore‐functionalised tris‐dipicolinate complexes [LnL₃]^3? (Ln=Yb and Nd) are thoroughly studied, revealing that only the Yb^III luminescence can be sensitized by a two‐photon excitation process. The stability of the complex in water is strongly enhanced by embedding in dispersible organosilicate nanoparticles (NPs). Finally, the spectroscopic properties of [NBu₄]₃[YbL₃] are studied in solution and in the solid state. The high brightness of the NPs allows imaging them as single objects using a modified two‐photon microscopy setup in a NIR‐to‐NIR configuration.     

Modular construction and hierarchical gelation of organooxotin nanoclusters derived from simple building blocks

Mixtures of an appropriate carboxylic acid and n-butylstannoic acid constitute modular gelation systems, in which the formation of a well-defined 'tin-drum' nanocluster subsequently underpins the hierarchical assembly of nanostructured fibres, which form self-supporting gel-phase networks in organic solvents.     

Probing amyloid fibril formation of the NFGAIL peptide by computer simulations

Amyloid fibril formation, as observed in Alzheimer's disease and type II diabetes, is currently described by a nucleation-condensation mechanism, but the details of the process preceding the formation of the nucleus are still lacking. In this study, using an activation-relaxation technique coupled to a generic energy model, we explore the aggregation pathways of 12 chains of the hexapeptide NFGAIL. The simulations show, starting from a preformed parallel dimer and ten disordered chains, that the peptides form essentially amorphous oligomers or more rarely ordered beta-sheet structures where the peptides adopt a parallel orientation within the sheets. Comparison between the simulations indicates that a dimer is not a sufficient seed for avoiding amorphous aggregates and that there is a critical threshold in the number of connections between the chains above which exploration of amorphous aggregates is preferred.     

Thermoelectric Properties of High-Entropy Wolframite Oxide: (CoCuNiFeZn)1−xGaxWO4

Herein, the synthesis of high-entropy wolframite oxide (CoCuNiFeZn)_1-xGaxWO₄ through standard solid-state route followed by spark plasma sintering and their structural, microstructural, and thermoelectric (TE) properties are investigated. X-ray diffraction pattern followed by patterns matching refinement shows a monoclinic structure with the volume of the unit cell decreasing with increasing Ga content. The optical bandgap for these oxides shows a cocktail effect in high-entropy configuration. The Seebeck coefficient indicates electrons as dominating charge carriers with a nondegenerate behavior. The electrical resistivity decreases with increasing temperature depicting a semiconducting nature. Thermal conductivity in high-entropy samples (κ ≈ 2.1 W m⁻¹ K⁻¹ @ 300 K) is significantly lower as compared to MgWO₄ (κ ≈ 11.5 W m⁻¹ K⁻¹ @ 300 K), which can be explained by the strong phonon scattering due to large lattice disorder in high-entropy configuration. The TE figure of merit zT increases with Ga doping via modifying all three TE parameters positively.     

Reductive Hydroformylation of Isosorbide Diallyl Ether

Isosorbide and its functionalized derivatives have numerous applications as bio-sourced building blocks. In this context, the synthesis of diols from isosorbide diallyl ether by hydrohydroxymethylation reaction is of extreme interest. This hydrohydroxymethylation, which consists of carbon-carbon double bonds converting into primary alcohol functions, can be obtained by a hydroformylation reaction followed by a hydrogenation reaction. In this study, reductive hydroformylation was achieved using isosorbide diallyl ether as a substrate in a rhodium/amine catalytic system. The highest yield in bis-primary alcohols obtained was equal to 79%.     

Critical mass for a Patlak–Keller–Segel model with degenerate diffusion in higher dimensions

This paper is devoted to the analysis of non-negative solutions for a generalisation of the classical parabolic-elliptic Patlak–Keller–Segel system with d ≥ 3 and porous medium-like non-linear diffusion. Here, the non-linear diffusion is chosen in such a way that its scaling and the one of the Poisson term coincide. We exhibit that the qualitative behaviour of solutions is decided by the initial mass of the system. Actually, there is a sharp critical mass M _c such that if solutions exist globally in time, whereas there are blowing-up solutions otherwise. We also show the existence of self-similar solutions for . While characterising the possible infinite time blowing-up profile for M  =  M _c , we observe that the long time asymptotics are much more complicated than in the classical Patlak–Keller–Segel system in dimension two. This paper is under the Creative Commons licence Attribution-NonCommercial-ShareAlike 2.5.     

The cylinder over the Koras–Russell cubic threefold has a trivial Makar-Limanov invariant

In 1996 Makar-Limanov established that the Koras–Russell cubic threefold