The asymmetric synthesis of a chiral, nonracemic π-conjugated system with D2 point group of symmetry, dodecaphenylene 4 is described. In the key step, (−)-sparteineand Cu(II)-mediated oxidation of 2,2′-dilithio-1,1′-biaryls in ether gives the corresponding dimers, tetra-o-phenylenes, in 80% isolated yields and 50–60% ee’s. X-Ray crystallography confi rms the structure of rac-4 and its molecular...

this paper uses the concept of meta-frontier to investigate the relationship between meta technology ratios (mtr) and different varieties in datepalms including; mazafati, rabi and zardan that are produced widely in sistan and baluchestan province of iran. we used a stratified sampling of 300 date farmers of this province in 2010, 2011 and 2012 and estimated a stochastic production frontier usi...

the present meta-analysis was conducted to provide a quantitative measure of the overall effects of task complexity on chinese efl learners’ language production. based on the strict inclusion criteria, 12 primary studies were synthesized according to key features. eleven of them were meta-analyzed to investigate effects of raising the resource-directing task complexity. results revealed that ...

smoking has become more prevalent in turkey than it has in those of western countries during the past decade. this study was conducted to make parameter estimations on gender related smoking habits with the minimum of variance. of the ninety-two researches related to smoking habits conducted from 1981 to 2003 in turkey, 60 were deemed appropriate for the application of meta analysis and meta re...

Thermal oils are nowadays largely employed as heat transfer fluids or cooling media in industrial and energy production plants. However, despite their widespread use, very few data currently available about chemical stability possible composition changes function of the operating temperatures, which crucial importance to evaluate lifetime these materials real conditions. In present work, a comm...

The design of an efficient pure blue emitter to achieve stable, long operating organic light-emitting diode (OLED) devices still poses a significant challenge. Although through phosphorescence and thermally activated delayed fluorescence concepts, stable monochrome green red OLEDs can be realized, the has been All efforts so far have resulted in severe efficiency roll-off limited device lifetim...