Synthesis and characterization of nickel(II) complexes with potentially pentadentate macrocyclic ligands having N3O2 donor set

Nickel(II) complexes of N₃O₂ donor macrocycles incorporating 17- to 19-membered macrocyclic rings have been prepared. Physical measurements ind     

Comparative study of recent phenomenological potentials for the NaCl-type alkali halides derived from elastic and dielectric data

A comparative study is presented of various phenomenological potentials for the NaCl-type alkali halides-based on elastic and dielectric data and on a “combination” of the Born model with a deformable ion mode-reported in recent years by Catlow, Diller and Norgett, by Corish, Parker and Jacobs, by Sangster et al. and by Hardy and Karo. First a critical analysis is made of the models adopted by the various AA and of the procedures to determine the pertinent parameters, emphasizing the different, often crude approximations used and the thermodynamic inconsistencies present in them. The quality of the fits achieved, and of the predictions made with the different models is then discussed. Finally, one compares directly the resulting effective pair potentials for the short-range interactions cation-anion, anion-anion and cation-cation, as well as the various types of parameters (specifically the potential parameters (Born repulsive parameters and van der Waals coefficients) and the shell-model parameters). One finds that the effective short-range potentials for each pair interaction in a given salt reported by the various AA-taken as a whole-have a sizeable indeterminacy, due both to the Born repulsive and vdW contributions.     

Unwanted combustion enhancement by C6F12O fire suppressant

Several agents are under consideration to replace CF₃Br for use in suppressing fires in aircraft cargo bays. In a Federal Aviation Administration (FAA) performance test simulating the explosion of an aerosol can, however, the replacements, when added at sub-inerting concentrations, have all been found to create higher pressure rise than with no agent, hence failing the test. Thermodynamic equilibrium calculations as well as perfectly-stirred reactor (PSR) simulations with detailed reaction kinetics, are performed for one of these agents, C₆F₁₂O (Novec 1230), to understand the reasons for the unexpected enhanced combustion rather than suppression. The high pressure rise with added agent is shown to depend on the amount of agent, and can only occur if a large fraction of the available oxidizer in the chamber is consumed, corresponding to stoichiometric proportions of fuel, oxygen, and agent. A kinetic model for the reaction of C₆F₁₂O in hydrocarbon–air flames has been developed. Stirred-reactor simulations predict that at higher agent loadings, the inhibition effectiveness of C₆F₁₂O is relatively insensitive to the overall stoichiometry, and the marginal inhibitory effect of the agent is greatly reduced, so that the mixture remains flammable over a wide range of conditions corresponding to those of the FAA test. The present findings are consistent with and support the earlier analyses for C₂HF₅ and CF₃Br, which were also evaluated in the FAA test.     

Visible-light photocatalysis of ZnO deposited on nanoporous Au

ZnO deposited on nanoporous Au showed photocatalytic decomposition toward methyl orange under visible light, unlike ZnO sputtered on flat Au without a nanoporous structure. First-principles calculations suggested that the surface lattice disorder in nanoporous Au induced a band gap narrowing and a large built-in electric field in the adjacent ZnO, resulting in the visible-light photocatalytic response.     

Development of cyclodextrin-based extract of <Emphasis Type="Italic">Lotus corniculatus</Emphasis> as a potential substrate reduction therapy in mucopolysaccharidoses type III

A novel sustainable and eco-friendly procedure simultaneously combining the use of ultrasound irradiation and hydroxypropyl-β-cyclodextrin (HPβCD) complexation was used to extract phytochemicals from Lotus corniculatus and to prepare flavonoid rich extract having potential as substrate reduction therapy of mucopolysaccharidosis type III (MPS III), a rare autosomal recessive lysosomal storage disorder. For that instance, Box-Behnken design and response surface methodology was employed to statistically assess the influence of HPβCD concentration, ultrasonic power, and extraction time on the total phenolic compounds, total flavonoids, total phenolic acids and radical scavenging activity (RSA) of the extracts prepared, chosen as the responses indicative of the product quality and performance. The potential of such optimised extract to modulate accumulation of gylcosoaminoglycans (GAGs) was evaluated on the fibroblast obtained from patients suffering from MPS type III. Optimized extract prepared by 45 min extraction using HPβCD at concentration of 20 mM and ultrasonic irradiation of 648 W was rich in flavonoids (1.36 mg/mL) and showed notable RSA of 1.04 mg/mL. Freeze-dried extract, at concentration of 3 and 6 µg/mL, reduced GAG levels in skin fibroblasts by 33.97 and 50.08%, respectively, without any toxic effects at given doses, showing a potential to be considered as a part of the substrate reduction therapy of MPS III.     

Photo-oxidation of aldehydes with molecular oxygen in the presence of catalytic bromine or hydrobromic Acid

Aldehydes were found to be oxidized with molecular oxygen to the corresponding carboxylic acid in the presence of catalytic hydrobromic acid or bromine under photo-irradiation.     

Aerobic photo-oxidative cleavage of the C-C double bonds of styrenes

Carbon tetrabromide enables us to carry out oxidative cleavage of the C-C double bonds of styrenes under aerobic photo-irradiation conditions. Oxidative cleavage of the various β-substituted styrenes produced benzoic acid in good yields. Since this reaction is found to be applicable to the α- or β-substituted styrenes, which showed very low reactivity under our previous cleavage reaction condition with FSM-16 and I₂, this reaction can be used complementarily.     

Tuning of Electronic Properties of Single‐Walled Carbon Nanotubes under Homogenous Conditions

Reversible and non‐bonding interaction between SWNTs and ODCB is observed from the analyses of visible near‐infrared absorption data and Raman spectroscopies (see spectra). The solvent effect on SWNTs effectively controls the electronic structure of SWNTs under homogeneous conditions.

     

Magnetism of fcc/fcc, hcp/hcp twin and fcc/hcp twin-like boundaries in cobalt

The magnetic moments of the fcc/fcc, hcp/hcp twin and fcc/hcp twin-like boundaries in cobalt were investigated by first-principles calculations based on density functional theory. The magnetic moments in fcc/fcc were larger than those of the bulk fcc, while the variations in the magnetic moment were complicated in hcp/hcp and fcc/hcp. The magnetovolume effect on the magnetic moment at the twin(-like) boundaries was investigated in terms of the local average atomic distance and the average deviation from equilibrium; however, the complicated variations in the magnetic moment could not be explained from the magnetovolume effect. Next, the narrowing (or broadening) of the partial density of states (PDOS) width of 3d orbitals, the number of occupied states for the spin-down channel, and the PDOS around the Fermi level were investigated. The entire variation in the magnetic moment at the twin(-like) boundaries could be understood in terms of these factors. Charge transfer occurred in hcp/hcp. In this case, the contributions of 4s and 4p electrons to the variation in the magnetic moment were relatively large.