Copper(I) complexes of bis(2-(diphenylphosphino)phenyl) ether: synthesis, reactivity, and theoretical calculations

The tricoordinated cationic Cu(I) complex [Cu(kappa2-P,P'-DPEphos)(kappa1-P-DPEphos)][BF4] (1) (DPEphos = bis(2-(diphenylphosphino)phenyl) ether) containing a dangling phosphorus center was synthesized from the reaction of [Cu(CH3CN)4][BF4] with DPEphos in a 1:2 molar ratio in dichloromethane. When complex 1 is treated with MnO2, elemental sulfur, or selenium, the uncoordinated phosphorus atom undergoes oxidation to form a P=E bond resulting in the formation of complexes of the type [Cu(kappa2-P,P'-DPEphos)(kappa2-P,E-DPEphos-E)][BF4] (2, E = O; 3, E = S; 4, E = Se) containing a Cu-E bond. The zigzag polymeric CuI complex [Cu(kappa2-P,P'-DPEphos)(micro-4,4'-bpy)]n[BF4]n (5) was prepared by the reaction of [Cu(CH3CN)4][BF4] with DPEphos and 4,4'-bipyridine in an equimolar ratio. The stereochemical influences of DPEphos on its coordination behavior are examined by density functional theory calculations.     

Antibacterial wollastonite supported excellent proliferation and osteogenic differentiation of human bone marrow derived mesenchymal stromal cells

Journal of Sol-Gel Science and Technology - Biocompatibility and bacterial infections are the primary concerns associated with the current bone graft substitutes. The application of...     

Development and characterization of a variable turbulence generation system

Experimental turbulent combustion studies require systems that can simulate the turbulence intensities [u′/U ₀ ~ 20–30% (Koutmos and McGuirk in Exp Fluids 7(5):344–354, 1989)] and operating conditions of real systems. Furthermore, it is important to have systems where turbulence intensity can be varied independently of mean flow velocity, as quantities such as turbulent flame speed and turbulent flame brush thickness exhibit complex and not yet fully understood dependencies upon both U ₀ and u′. Finally, high pressure operation in a highly pre-heated environment requires systems that can be sealed, withstand high gas temperatures, and have remotely variable turbulence intensity that does not require system shut down and disassembly. This paper describes the development and characterization of a variable turbulence generation system for turbulent combustion studies. The system is capable of a wide range of turbulence intensities (10–30%) and turbulent Reynolds numbers (140–2,200) over a range of flow velocities. An important aspect of this system is the ability to vary the turbulence intensity remotely, without changing the mean flow velocity. This system is similar to the turbulence generators described by Videto and Santavicca (Combust Sci Technol 76(1):159–164, 1991) and Coppola and Gomez (Exp Therm Fluid Sci 33(7):1037–1048, 2009), where variable blockage ratio slots are located upstream of a contoured nozzle. Vortical structures from the slots impinge on the walls of the contoured nozzle to produce fine-scale turbulence. The flow field was characterized for two nozzle diameters using three-component Laser Doppler velocimetry (LDV) and hotwire anemometry for mean flow velocities from 4 to 50 m/s. This paper describes the key design features of the system, as well as the variation of mean and RMS velocity, integral length scales, and spectra with nozzle diameter, flow velocity, and turbulence generator blockage ratio.     

Radical induced fragmentation in a benzoxocane ring system: application to the synthesis of elvirol and a formal synthesis of 7,8-dihydroxycalamenene

A novel radical induced fragmentation in a benzoxocane ring system has been employed for a synthesis of elvirol 8 and an advanced intermediate in the synthesis of 7,8-dihydroxycalamenene 20. The coumarins 9, 22 were taken through a sequence of reactions to the benzoxocanols 16, 30, which when subjected to Barton’s deoxygenation conditions involving conversion to the corresponding thionocarbonates 17, 31 followed by exposure to tri-n-butyltin hydride, underwent a radical induced fragmentation to furnish elvirol 8 and the curcuphenol derivative 32, which was converted to the dimethoxy compound 33. This had served as an advanced intermediate in a previous synthesis of dihydroxycalamenene.     

Scattering by small defects in the neighbourhood of a fluid-solid interface

The scattering of incident plane elastic waves by a varietyof different defects that lie upon a fluid-solid interface isconsidered here using matched asymptotic expansions. The expansionscheme is developed in terms of a parameter , the ratio of typicaldefect length scale to a typical wavelength of the incidentfield, taken to be small. Three different canonical situations occur and these are illustratedvia three specific examples treated here: a rigid strut, anedge crack, and a rigid strip. In each case the leading-ordermatching is performed to identify the leading-order contributionof the defect to the acoustic field in the far field. In particular,each defect is identified with a source of dipole response ininterfacial stress of displacement. It is shown in the limit as s<<s1 that in the inner problemsthe fluid and solid pieces uncouple in a particularly convenientmanner allowing analytical solutions to be deduced. These arethen matched with appropriate outer solutions.