Effect of metal dilution on the light-induced spin transition in [Fe(x)Zn(1-x)(phen)2(NCS)2] (phen = 1,10-phenanthroline)

The thermal and light-induced spin transitions in [Fe(x)Zn(1-x)(phen)2(NCS)2] (phen = 1,10-phenantholine) have been investigated by magnetic susceptibility, photomagnetism and diffuse reflectivity measurements. These complexes display a thermal spin transition and undergo the light-induced excited spin state trapping (LIESST) effect at low temperatures. For each compound, the thermal spin transition temperature, T1/2, and the relaxation temperature of the photo-induced high-spin state, T(LIESST), have been systematically determined. It appears that T1/2 decreases with the metal dilution while T(LIESST) remains unchanged. This behaviour is discussed on the basis of the kinetic study governing the photo-induced back conversion.     

Pyrolysis of meat-meal and bone-meal blends in a mechanically fluidized reactor

Nowadays, meat and bone meal produced in animal slaughterhouses and farms has become an important waste. Landfilling this residue means that its energy is lost. The pyrolysis of meat and bone meal produces a solid fraction which can be used as a fuel or as solid adsorbent, a liquid fraction with possible chemical applications and a low heating value gas.In this work, meat and bone meal has been pyrolyzed with a new technology, a mechanically fluidized reactor (MFR). This MFR is a stainless steel cylinder with 7.7 cm i.d., and an internal height of 15.6 cm. The meat and bone meal pyrolysis was carried out at 500 °C of temperature. The effect of several factors (mixer speed, heating rate and feed composition) on the product yields, bio-oil phases yield, bio-oil heating value and char heating value was studied. The amount of pure meat meal in the feed had a strong impact on product yields and compositions. The liquid yield, which has two phases, varies from 22 wt% to 52 wt% when the raw material fed changed from pure bone meal to pure meat meal.     

Effect of successive sprays on liquid distribution in fluidized beds

In processes such as Fluid Coking^?,agglomerate formation should be minimized since it reduces the yield of valuable products,and degrades operability because of the fouling of internals.An experimental model,consisting of an aqueous solution of gum arabic with a dye,has been successfully developed to simulate the formation of agglomerates in the Fluid Coking^?process,where bitumen is sprayed into a fluidized bed of coke particles The particles wetted by a spray could be predicted by assuming that all the particles in the wake of bubbles formed from the tip of the spray jet have been wetted by the injected liquid.The transfer of liquid from particles wetted with the spray to dry bed particles was relatively ineffective,as the number of wet particles increased by only 50%.With successive liquid injections,the proportion of the liquid trapped in agglomerates increases in latter injections:large agglomerates from earlier injections accumulate above the grid and are carried by gas bubbles into the spray jet cavity,where they seed fresh agglomerates.     

The Interplay between Strain,Sn Content,and Temperature on Spatially Dependent Bandgap in Ge1−x Sn x Microdisks

Germanium–tin (GeSn) microdisks are promising structures for complementary metal–oxide–semiconductor-compatible lasing. Their emission properties depend on Sn concentration, strain, and operating temperature. Critically, the band structure of the alloy varies along the disk due to different lattice deformations associated with mechanical constraints. An experimental and numerical study of Ge_1−x Sn _x microdisk with Sn concentration between 8.5 and 14 at% is reported. Combining finite element method calculations, micro-Raman and X-ray diffraction spectroscopy enables a comprehensive understanding of mechanical deformation, where computational predictions are experimentally validated, leading to a robust model and insight into the strain landscape. Through micro-photoluminescence experiments, the temperature dependence of the bandgap of Ge_1−x Sn _x is parametrized using the Varshni formula with respect to strain and Sn content. These results are the input for spatially dependent band structure calculations based on deformation potential theory. It is observed that Sn content and temperature have comparable effects on the bandgap, yielding a decrease of more than 20 meV for an increase of 1 at% or 100 K, respectively. The impact of the strain gradient is also analyzed. These findings correlate structural properties to emission wavelength and spectral width of microdisk lasers, thus demonstrating the importance of material-related consideration on the design of optoelectronic microstructures.     

Patroids

A matroid M over a set E of elements is semiseparated by a partition {S¹, S²} of E iff rank E = rank S¹ + rank S² + 1. Such a semiseparation defines in each Sⁱ a pair of matroids or patroid Pⁱ = (Mⁱ, mⁱ); the two patroids P¹, P² weld to form M. The operations of removing and contracting a non-degenerate element of a matroid produce a patroid. The properties of patroids, their bases, and circuits are discussed.     

Scanning electrochemical microscopy #54. Application to the study of heterogeneous catalytic reactions-hydrogen peroxide decomposition

A scanning electrochemical microscopy (SECM) approach for the analysis of heterogeneous catalytic reactions at solid-liquid interfaces is described and applied. In this scheme, reactant, generated at a tip, undergoes a reaction (e.g., disproportionation) at the substrate. The theoretical background for this study, performed by digital simulations using a finite difference method, considers a chemical reaction at the substrate with general stoichiometry. In this case, the fraction of regenerated mediator (nu(S)) may differ with respect to a substrate reaction that is the reverse of the tip reaction, resulting in an asymmetric mediator loop. Simulated tip current transients and approach curves at different values of the kinetic rate constant for reactions where nu(S) < 1 were used to analyze this new SECM situation. This approach was used to study the catalytic decomposition of hydrogen peroxide (HO2- --> 1/2O2 + OH-), where nu(S) = 0.5, on supported catalysts. A gold-mercury amalgam tip was used to quantitatively reduce dissolved O2 (mediator) to HO2-, which was decomposed back to oxygen at the catalyst substrate. Rate constants for the decomposition reaction on immobilized catalase and Pt particles were measured at different pH values by the correlation of experimental approach curves with the theoretical dependencies.