Detection of hydrogen peroxide produced at a liquid/liquid interface using scanning electrochemical microscopy

Scanning electrochemical microscopy (SECM) was used to monitor in situ hydrogen peroxide (H₂O₂) produced at a polarized water/1,2-dichloroethane (DCE) interface. The water/DCE interface was formed between a DCE droplet containing decamethylferrocene (DMFc) supported on a solid electrode and an acidic aqueous solution. H₂O₂ was generated by reducing oxygen with DMFc at the water/DCE interface, and was detected with a SECM tip positioned in the vicinity of the interface using a substrate generation/tip collection mode. This work shows unambiguously how the H₂O₂ generation depends on the polarization of the liquid/liquid interface, and how proton-coupled electron transfer reactions can be controlled at liquid/liquid interfaces.     

Magnetocaloric Effect in Alloy Fe49Rh51 in Pulsed Magnetic Fields up to 50 T

Physics of the Solid State - Magnetocaloric effect (MCE) in pulsed magnetic fields up to 50 T was directly studied in alloy Fe49Rh51. An inverse MCE ΔT ≈ –8 K is observed at...     

Effects of lithium on the electronic properties of porous Ge as anode material for batteries

Recently, the need of improvement of energy storage has led to the development of Lithium batteries with porous materials as electrodes. Porous Germanium (pGe) has shown promise for the development of new generation Li-ion batteries due to its excellent electronic, and chemical properties, however, the effect of lithium in its properties has not been studied extensively. In this contribution, the effect of surface and interstitial Li on the electronic properties of pGe was studied using a first-principles density functional theory scheme. The porous structures were modeled by removing columns of atoms in the [001] direction and the surface dangling bonds were passivated with H atoms, and then replaced with Li atoms. Also, the effect of a single interstitial Li in the Ge was analyzed. The transition state and the diffusion barrier of the Li in the Ge structure were studied using a quadratic synchronous transit scheme.     

Structure, electronic, and optical properties of TiO2 atomic clusters: an ab initio study

Atomic clusters of TiO(2) are modeled by means of state-of-the-art techniques to characterize their structural, electronic and optical properties. We combine ab initio molecular dynamics, static density functional theory, time-dependent density functional theory, and many body techniques, to provide a deep and comprehensive characterization of these systems. TiO(2) clusters can be considered as the starting seeds for the synthesis of larger nanostructures, which are of technological interest in photocatalysis and photovoltaics. In this work, we prove that clusters with anatase symmetry are energetically stable and can be considered as the starting seeds to growth much larger and complex nanostructures. The electronic gap of these inorganic molecules is investigated, and shown to be larger than the optical gap by almost 4 eV. Therefore, strong excitonic effects appear in these systems, much more than in the corresponding bulk phase. Moreover, the use of various levels of theory demonstrates that charge transfer effects play an important role under photon absorption, and therefore the use of adiabatic functionals in time dependent density functional theory has to be carefully evaluated.     

A simple method for obtaining the fully developed heat transfer coefficient in turbulent pipe flow

This paper addresses a distinct and direct computational technique for calculating the characteristics of a thermally developed turbulent pipe flow in a circular pipe. The technique seeks to replace a partial differential energy equation into an equivalent ordinary differential energy equation. The latter is valid in the thermally developed region of the pipe. Numerical results show good agreement with experimental observations for gas and water flows over a wide range of Reynolds numbers.