Efficient reductive selenation of aromatic aldehydes to symmetrical diselenides with Se/CO/H2O under atmospheric pressure

An efficient method for the synthesis of symmetrical diselenides is described. Reductive selenation of aromatic and heterocyclic aromatic aldehydes (ArCHO) with Se/CO/H2O in DMF afforded diselenides (ArCH2SeSeCH2Ar) in yields up to 94% under atmospheric pressure without use of a base.

Modeling All-sky Global Solar Radiation Using MODIS Atmospheric Products: A Case Study in Qinghai-Tibet Plateau

The surface solar radiation (SSR) is of great importance to bio-chemical cycle and life activities. However, it is impossible to observe SSR directly over large areas especially for rugged surfaces such as the Qinghai-Tibet Plateau. This paper presented an improved parameterized model for predicting all-sky global solar radiation on rugged surfaces using Moderate Resolution Imaging Spectroradiometer (MODIS) atmospheric products and Digital Elevation Model (DEM). The global solar radiation was validated using 11 observations within the plateau. The correlation coefficients of daily data vary between 0.67-0.86, while those of the averages of 10-day data are between 0.79-0.97. The model indicates that the attenuation of SSR is mainly caused by cloud under cloudy sky, and terrain is an important factor influencing SSR over rugged surfaces under clear sky. A positive relationship can also be inferred between the SSR and slope. Compared with horizontal surfaces, the south-facing slope receives more radiation, followed by the west- and east-facing slopes with less SSR, and the SSR of the north-facing slope is the least.

Partial Evaporation of Strontium Zirconate During Atmospheric Plasma Spraying

Perovskite-type SrZrO3 has been investigated as a candidate material for thermal barrier coating application. During plasma spraying of SrZrO3, SrO volatilized more than ZrO2 and the coating composition deviates from initial stoichiometry. In this investigation, partial evaporation was investigated by spraying SrZrO3 powders into water. The influences of spraying current, distance and particle size of the powder on the partial evaporation were also investigated in a quantitative way. With optimized spraying parameters, stoichiometric SrZrO3 coating was produced by adding an excess amount of Sr in the precursors before plasma spraying to compensate for the volatilized component.

Templated assembly of mu(5)-CO32- decanuclear praseodymium and neodymium clusters through spontaneous fixation of atmospheric carbon dioxide

Reactions of Ln(III) acetate (Ln = Pr and Nd) and a polydentate Schiff-base in a mixture of methanol and acetonitrile resulted in the unprecedented assembly of novel Ln(10) aggregates containing two Ln(5) pentagons templated by mu(5)-CO32-, introduced via spontaneous fixation of atmospheric carbon dioxide. Magnetic analysis using an expression including the ligand field effects and molecular field approximation indicates weak antiferromagnetic coupling between the metal ions. This synthetic approach may represent a promising new route toward the design of new lanthanide clusters and novel multifunctional materials.

Subtropical dipole mode in the Southern Hemisphere: A global view

A global wavenumber-3 dipole SST mode is showed to exist in the Southern Hemisphere subtropical climate variability in austral summer. A positive (negative) phase of the mode is characterized by cool (warm) SST anomalies in the east and warm (cool) SST anomalies in the southwest of the south Indian, Pacific, and Atlantic Oceans, respectively. This coherent dipole structure is largely a response of ocean mixed layer to the atmospheric forcing characterized by migration and modulation of the subtropical high-pressures, in which the latent heat flux play a leading role through wind-induced evaporation, although ocean dynamics may also be crucial in forming SST anomalies attached to the continents. Exploratory analyses suggest that this mode is strongly damped by the negative heat flux feedback, with a persistence time about three months and no spectral peak at interannual to decadal time scales. As the subtropical dipole mode is linearly independent of ENSO and SAM, whether it represents an additional source of climate predictability should be further studied. Citation: Wang, F. (2010), Subtropical dipole mode in the Southern Hemisphere: A global view, Geophys. Res. Lett., 37, L10702, doi: 10.1029/2010GL042750.