Determination of the Effective Permeability of Doubly Porous Materials by a Two-Scale Homogenization Approach

Transport in Porous Media - The present work is dedicated to determining the effective permeability of doubly porous materials made of a solid phase comprising a network of interconnected pores at...     

A New Sesquiterpene Glycoside from Leaves of Bombax ceiba

Chemistry of Natural Compounds - A new sesquiterpene glycoside, ceibanoside (1), was isolated from the leaves of Bombax ceiba, together with the previously-reported quercetin (2), kaempferol (3),...     

Effect of Operating Conditions on the Yield of 2-Hydroxyterephthalic Acid for Tracing •OH Radical in Electrochemical Process

Moscow University Chemistry Bulletin - The boron-doped diamond electrode has been widely applied in electrochemical process for wastewater treatment based on the generation of hydroxyl radicals...     

Stable Triarylmethyl Radicals and Cobalt(II) Ions Based 1D/2D Coordination Polymers

The incorporation of organic radicals into coordination polymers was considered as a promising strategy to promote metal-ligand exchange interactions, but there are only a very limited number of stable organic radical-based ligands that can serve well such a purpose. Herein, we report two new tris(2,4,6-trichlorophenyl)methyl (TTM) radical-based ligands L1 and L2 with two and three imidazole substituents, respectively. The imidazole unit serves as a coordination site and it can also stabilize the TTM radical by intramolecular donor–acceptor interaction. Coordination of L1 and L2 with cobalt(II) ions gave the corresponding one- ( CoCP - 1 ) and two-dimensional ( CoCP - 2 ) coordination polymers, the structures of which were confirmed by X-ray crystallographic analysis. Magnetic measurements and theoretical calculations suggest antiferromagnetic coupling between the paramagnetic cobalt(II) ions and the radical ligands. Our study provides a rational design for stable organic radical-based ligands and further demonstrated the feasibility of a metal–radical approach toward magnetic materials.     

Bis[N-alkyl-NN-di(2-pyridylmethyl)amine]zinc(II) perchlorates display cis-facial stereochemistry in solid state and solution

N-Alkyl-N,N-di(2-pyridylmethyl)amines are ligands commonly used by supramolecular chemists in molecular recognition and sensing applications. The metal coordination complexes of these ligands, in particular those with 2:1 (ligand:metal) molar ratio, have not been sufficiently characterised in solution. In this work, bis[N-alkyl-N,N-di(2-pyridylmethyl)amine]zinc(II) perchlorates are characterised in both solid and solution phases, using X-ray crystallography and NMR spectroscopy, respectively. Only the cis-facial stereoisomer is observed. Density functional theory calculations support the thermodynamic preference for this stereochemistry, as in one representative case the gas phase energy of the cis-facial configuration is lower than those of the trans-facial and meridional configurations by 4.0 and 4.5 kcal/mol, respectively.     

Total synthesis of calothrixins A and B via oxidative radical reaction of cyclohexenone with aminophenanthridinedione

Bioactive indolo[3,2-j]phenanthridine alkaloids, calothrixin B and its N-oxide derivative calothrixin A have been synthesized via an oxidative free radical reaction. Calothrixin B is generated from the commercially available 2,4,5-trimethoxybenzaldehyde in only seven steps. The key step in this synthesis is the Mn(OAc)₃ mediated oxidative free radical reaction of 9-(benzylamino)phenanthridine-7,10-dione with cyclohexenone to form 12-benzyl-12H-indolo[3,2-j]phenanthridine-7,13-dione.     

Micro‐photoluminescence spectroscopy on heavily‐doped layers of silicon solar cells

We report and explain the photoluminescence spectra emitted from silicon solar cells with heavily‐doped layers at the surface. A micro‐photoluminescence spectroscopy system is employed to investigate the total spectrum emitted from both the heavily‐doped layer and the silicon substrate with micron‐scale spatial resolution. The two regions of the device give rise to separate photoluminescence peaks, due to band‐gap narrowing effects in the highly‐doped layer. Two key parameters, the absorption depth of the excitation wavelength, and the sample temperature, are shown to be critical to reveal the separate signatures from the two regions. Finally, this technique is applied to locally diffused and laser‐doped regions on silicon solar cell pre‐cursors, demonstrating the potential value of this micron‐scale technique in studying and optimizing locally doped regions. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Transient conjugated heat transfer analysis from a sphere

The phenomena of conjugate unsteady heat transfer from a solid spherical particle in a convective environment is numerically investigated for Reynolds numbers in the range from 0.1 to 100. The flow and energy equations for both dispersed and continuous phases are solved using a Chebyshev-Legendre spectral method. This work is an extension of the previous effort of simulating flow around a sphere using spectral method [2] to include heat transfer. General findings indicate that quasi-steady analysis underestimates the overall heat transfer rate significantly at very early time stages, however the extent of underprediction becomes less as time progresses. The underprediction of the quasi-steady assumption becomes larger as Reynolds number increases for a fixed Prandtl number.Der Modellfall des gekoppelten, nichtstationären Wärmeübergangs von einem festen, kugelförmigen Partikel an ein Konvektionsfeld wird numerisch für Reynoldszahlen von 0,1 bis 100 untersucht. Die Lösung der Impuls- und Energiegleichungen für den dispersen wie den kontinuierlichen Bereich erfolgt unter Verwendung einer Chebyshev-Legendre Spektralmethode. Diese Arbeit setzt frühere Untersuchungen fort, wobei jetzt unter Verwendung derselben Methode auch der Wärmeübergang Berücksichtigung findet. Es zeigte sich, daß die quasistationäre Behandlung den Gesamtwärmeübergang im frühen Anlaufstadium erheblich unterbewertet. Dieser Effekt verringert sich im weiteren Verlauf des Austauschvorganges; er wächst (bei festgehaltener Prandtlzahl) mit der Reynoldszahl.The authors would like to thank Dr. R. W. Douglass for his valuable comments and Dr. M. J. Oliver and Mr. V. A. Mousseau for their assistance in running the computer program. This work is performed under the auspices of the U.S. Department of Energy, contract number DE-AC07-765-ID01570, and was supported in part by the INEL Long-Term Research Inditiatives Program.