Electrochemical study of silver thiosulphate reduction in the absence and presence of ultrasound

The electrochemical reduction of silver thiosulphate was studied potentiostatically on platinum electrodes in the absence and presence of ultrasound (20 kHz). This system is irreversible and the reaction is both diffusion and kinetically controlled. The slowest step is the kinetic reaction especially the chemisorption of ions at the electrode surface. Ultrasound greatly improves the mass transport, which can be explained by changing from diffusion to mainly convection. This paper reports the effect of ultrasound upon electrode kinetic and mass-transport parameters at various RDE rotation speeds and ultrasonic intensities. It was found that the heterogeneous rate constant (kf) is improved in the presence of ultrasound due to the increase in the formal or standard heterogeneous rate constant (k0) (approximately by 10-fold under sonication).     

X-Ray photoemission study of CuIr2S4: Ir3+-Ir4+ charge ordering and the effect of light illumination

We have studied the electronic structure of the spinel-type compound CuIr2S4 using x-ray photoemission spectroscopy (XPS). CuIr2S4 undergoes a metal-insulator transition (MIT) at approximately 226 K. In going from the metallic to insulating states, the valence-band photoemission spectrum shows a gap opening at the Fermi level and a rigid-band shift of approximately 0.15 eV. In addition, the Ir 4f core-level spectrum is dramatically changed by the MIT. The Ir 4f line shape of the insulating state can be decomposed into two contributions, consistent with the charge disproportionation of Ir3+:Ir4+=1:1. XPS measurements under laser irradiation indicate that the charge disproportionation of CuIr2S4 is very robust against photo-excitation in contrast to Cs2Au2Br6 which shows photo-induced valence transition.     

Efficient total syntheses of polygodial and drimenin.

A short and stereoselective total synthesis of (±) polygodial and drimenin is presented. The efficiency of the synthesis is due to the easy access to intermediate diol $\text{4}$ and its successful direct oxidation into polygodial.     

The size of the proton

The root-mean-square (rms) charge radius r _p of the proton has so far been known only with a surprisingly low precision of about 1% from both electron scattering and precision spectroscopy of hydrogen. We have recently determined r _p by means of laser spectroscopy of the Lamb shift in the exotic “muonic hydrogen” atom. Here, the muon, which is the 200 times heavier cousin of the electron, orbits the proton with a 200 times smaller Bohr radius. This enhances the sensitivity to the proton’s finite size tremendously. Our new value r _p?=?0.84184 (67) fm is ten times more precise than the generally accepted CODATA-value, but it differs by 5 standard deviations from it. A lively discussion about possible solutions to the “proton size puzzle” has started. Our measurement, together with precise measurements of the 1S–2S transition in regular hydrogen and deuterium, also yields improved values of the Rydberg constant, R _?∞??=?10,973,731.568160 (16) m^???1.     

Tunable magnetic interaction at the atomic scale in oxide heterostructures

We report on a systematic study of a number of structurally identical but chemically distinct transition metal oxides in order to determine how the material-specific properties such as the composition and the strain affect the properties at the interface of heterostructures. Our study considers a series of structures containing two layers of ferromagnetic SrRuO?, with antiferromagnetic insulating manganites sandwiched in between. The results demonstrate how to control the strength and relative orientation of interfacial ferromagnetism in correlated electron materials by means of valence state variation and substrate-induced strain, respectively.     

Modeling heat transfer and transcrystallization kinetics during processing of polymer-based composites materials

Transcrystallization phenomena is a key issue to master for better understanding the role on the fiber-matrix interface in composites materials behavior during and after processing. In this paper, a non-isothermal kinetics model is presented to consider crystallization in fiber-based composite with thermoplastic matrix. The model extends Schneider's formulation to describe the development of transcrystalline layers around fibers. It also mentions the possibility to easily account for shear and flow conditions in addition to the transcrystallinity. Another approach, based on the volume fractions, giving the same results, is also introduced for comparison. Then, a parametric study is proposed in order to demonstrate the relevance of the developed model by comparing its results to well-known expecting behavior from the literature. Finally, an attempt is made to compare this model to the one proposed previously in the literature by Durin and al. after correcting some unclear points in the latter.     

Working group report: Heavy-ion physics and quark-gluon plasma

This is the report of Heavy Ion Physics and Quark-Gluon Plasma at WHEPP-09 which was part of Working Group-4. Discussion and work on some aspects of quark-gluon plasma believed to have created in heavy-ion collisions and in early Universe are reported.     

Synthesis of Primary Amines by One-Pot Reductive Amination of Aldehydes

We report here a novel, one-pot, two-step reductive amination of aldehydes for the atom-economical synthesis of primary amines. The amination step has been carried out with hydroxylammonium chloride and does not require the use of a base. In the subsequent reduction step, a metal zinc/hydrochloride acid system has been used. This method is applicable to both aliphatic and aromatic aldehydes. The operational simplicity, the short reaction times, and the mild reaction conditions add to the value of this method as a practical alternative to the reductive amination of aldehydes.

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