Characteristics investigation on heat transfer growth of sonochemically synthesized ZnO-DW based nanofluids inside square heat exchanger

Journal of Thermal Analysis and Calorimetry - In recent decades, the growth of heat transfer using nanomaterials in the conventional base fluid has caught the attention of researchers...     

Synthesis of diisocyanides with phenolic groups and their polymerization to helically chiral poly(quinoxaline‐2,3‐diyl)s

The development of synthetic routes which lead to five new diisocyanide monomers with one or two phenolic groups is described. Their polymerization behavior is studied with Pd‐ and Ni‐based initiators, as well as under microwave irradiation. The polymerizability is mainly dominated by steric effects as is concluded from experiments using different protecting groups. Chiroptical properties of these new polymers are studied by CD‐spectroscopy. After deprotection, helically chiral poly(quinoxalin‐2,3‐diyl)s are obtained which display a Brønsted function attached to a stereolabile biaryl axis whose configuration should be influenced by the chiral polymer backbone. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1320–1329     

The effect of rapid rotation on a vertical bridgman furnace at large Rayleigh number

In quasi-steady operation, convection currents in a Bridgmandevice, used for producing a semi-conductor crystal, createinhomogeneities that may make the crystal unusable. It has oftenbeen suggested that additional forces due to rotation or magnetismmight be efficacious in reducing the segregation of the elementsof the alloy. It has been found that, over a wide range of rotationrates, there is no improvement in performance due to rotationabout the vertical axis. However, numerical results that havebeen obtained previously (Lee & Pearlstein, J. Crys. Growth240, 2002) indicate that, when effects of centrifugal buoyancyare introduced, a substantial reduction in segregation is achieved.In the work reported here, by contrast, in which we extend previouslarge-Rayleigh-number asymptotic analysis to include centrifugalbuoyancy, we find no improvement in radial segregation, butrather increasing segregation with increasing rotation rate.     

Versuche zur Totalsynthese von Brefeldin A

Preliminary results leading towards the total synthesis of Brefeldin A are presented.     

Beiträge zur Chemie des Phosphors. 203 [1].(t- BuSi)4P3Cl3, das erste Silaphosphan mit Norcuban-Struktur

Contributions to the Chemistry of Phosphorus. 203. (t-BuSi)₄P₃Cl₃ – The First Silaphosphane with a Structure Analogous to Norcubane The reaction of t-BuSiCl₃ with LiAl(PH₂)₄ yields the compound (t-BuSi)₄P₃Cl₃ ( 1 ), which has been isolated in pure form. According to NMR spectroscopic investigations and an X-ray single-crystal analysis, 1 is 2,4,6,7-tetra-tert-butyl-2,4,7-trichloro-1,3,5-triphospha-2,4,6,7-tetrasilatricyclo[3.1.1.0^3,6]heptane and thus the first silaphosphane with a structure analogous to norcubane. The compound crystallizes monoclinically in the space group P2₁/n with a = 1102.1 pm, b = 1609.2 pm, c = 1612.8 pm, β = 90.90° and Z = 4. The main structural feature is a cube alternately composed of Si and P, from which one phosphorus atom has been removed. The Si atoms are each substituted by t-Bu groups, the three adjacent to the missing corner additionally by Cl atoms.     

Der Gaskomplex MnAlF5 und sein Einfluß auf die sublimative Reinigung von AlF3

The Gas Complex MnAlF₅ and its Influence on the Purification of AlF₃ by Sublimation The gas complex MnAlF₅ has been determined mass spectroscopically by the ions MnAlF₅⁺ and MnAlF₄⁺. The gas complex MnAlF₅ is formed above 973 K by heating up mixtures of AlF₃/MnF₂ or AlF₃ · 3 H₂O endowed with Mn²⁺ or by heating up solid MnAlF₅ too. At 1 008 K the enthalpie of dissociation is 197 kJ/mole. The equilibrium structures of the high spin molecule MnAlF₅ (S = 5/2) were examined with ab initio calculations at the HF-level by comlete gradient optimizing. Two minimum structures were found on the potential energy surface. A bidentate fluorine bridged structure was found to be the most stable at the HF-level. Vibrational frequencies and thermodynamic functions of complex formation were estimated for both minimum structures. The importance of the formation of the gas complex for the separation of MnF₂ and AlF₃ by sublimation is discussed.