Fe(NO3)3 as an efficient catalyst for regio- and stereo-controlled ring expansion of 1,2-diaroyl-3-arylaziridines

Several 1,2-diaroyl-3-arylaziridines were previously prepared conveniently and used in the preparation of 5-benzoyl-2,4-diaryl oxazolines in the presence of NaI. In this work, synthesis of some trans-4-benzoyl-2,5-diaryl oxazolines by a regio- and stereo-controlled reaction in the presence of Iron (III) nitrate at room temperature is reported. A plausible mechanism has been proposed for ring expansion of N-acyl aziridines to oxazolines.     

Regio- and stereo-controlled isomerization of 1,2-diaroyl-3-aryl aziridines to the corresponding N-((Z)-1-oxo-1,3-diphenylprop-2-en-2-yl) benzamide

Regio- and stereo-controlled isomerization of 1,2-diaroyl-3-aryl aziridines to the corresponding N-((Z)-1-oxo-1,3-diphenylprop-2-en-2-yl) benzamide in the presence of diethyl thiourea in room temperature is described. A plausible mechanism has been proposed. The structures of the products were confirmed by X-ray analysis.     

Block liposomes from curvature-stabilizing lipids: connected nanotubes, -rods, or -spheres

We report on the discovery of block liposomes, a new class of chain-melted (liquid) vesicles, with membranes comprised of mixtures of the membrane-curvature-stabilizing multivalent lipid MVLBG2 of colossal charge +16 e and neutral 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine (DOPC). In a narrow MVLBG2 composition range (8-10 mol%), cryo-TEM revealed block liposomes consisting of distinctly shaped, yet connected, nanoscale spheres, pears, tubes, or rods. Unlike typical liposome systems, where spherical vesicles, tubular vesicles, and cylindrical micelles are separated on the macroscopic scale, within a block liposome, shapes are separated on the nanometer scale. Diblock (pear-tube) and triblock (pear-tube-pear) liposomes contain nanotubes with inner lumen diameter of 10-50 nm. Diblock (sphere-rod) liposomes were found to contain micellar nanorods approximately 4 nm in diameter and several micrometers in length, analogous to cytoskeletal filaments of eukaryotic cells. Block liposomes may find a range of applications in chemical and nucleic acid delivery and as building blocks in the design of templates for hierarchical structures.     

Optimal repair allocation in a series system expected discounted operation time criterion

Consider a series system with n repairable components maintained by a single repairman. The following assumptions are made. Component failure and repair times are independent, exponentially distributed, random variables. Component failures can occur even while the system is not functioning and it is possible to reassign the repairman among failed components instantaneously. It is shown that the policy which always assigns the repairman to the failed component with the smallest failure rate among the failed ones maximizes the expected discounted system operation time irrespective of the values of the repair rates and the discount rate     

Extension of the volume-of-fluid method for analysis of free surface viscous flow in an ideal gas

The volume-of-fluid (VOF) method is a simple and robust technique for simulating free surface flows with large deformations and intersecting free surfaces. Earlier implementations used Laplace's formula for the normal stress boundary condition at the interface between the liquid and vapour phases. We have expanded the interfacial boundary conditions to include the viscous component of the normal stress in the liquid phase and, in a limited manner, to allow the pressure in the vapour phase to vary. Included are sample computations that show the accuracy of added third-order-accurate differencing schemes for the convective terms in the Navier-Stokes equation (NSE), the viscous terms in the normal stress at the interface and the solution of potential flow in the vapour phase coupled with the solution of the NSE in the liquid phase. With these modifications we show that the VOF method can accurately predict the instability of a thin viscous sheet flowing through a stagnant vapour phase.     

A New Method for Analysis of the Fluid Interaction with a Deformable Membrane

The lattice Boltzmann cellular automaton method has been successfully extended for analysis of fluid interactions with a deformable membrane or web. The hydrodynamic forces on the solid web are obtained through computation of the fluid flow stress at the moving boundary using the lattice Boltzmann method. Analysis of solid boundary deformation or vibration due to hydrodynamic force is based on Newtonian dynamics and a molecular dynamic type approach.     

Crystallisation behaviour during tensile loading of laser treated Fe–Si–B metallic glass

Effect of tensile loading on crystallisation behaviour of as-cast and laser thermal treated Fe–Si–B metallic glass foils was investigated. Tensile loading lacked any marked influence on the crystallisation behaviour of as-cast and structurally relaxed laser-treated metallic glass foils. Furthermore, the average crystallite/grain size in partially crystallised laser-treated metallic glass foil was nearly equal to the average crystallite/grain size in the region away from the fracture of the same partially crystallised laser-treated metallic glass foil after tensile loading. However, a significant crystallite/grain growth/coarsening of the order of two and half times was observed in the fractured region compared to the region around it for the laser-treated partially crystallised metallic glass foils. The simultaneous effects of stress generation and temperature rise during tensile loading were considered to play a key role in crystallite/grain growth/coarsening.     

Mammalian alkaloids: Synthesis and O-methylation of (S)- and (R)-3′-hydroxycoclaurine and their N-methylated analogues with S-adenosyl-L-[methyl-14C]methionine in presence of mammalian catechol O-methyltransferase

O-Methylation of the optically active 3′-hydroxycoclaurines 3a and 3b and of the N-methylated analogs 5a,b with S-adenosyl-L -[methyl-¹⁴C]methionine in presence of mammalian COMT was investigated in vitro. The N-unsubstituted (1S)- and (1R )-isomers 3a and 3b , respectively, afforded almost equal amounts of the corresponding N-norreticuline 4 and N-nororientaline 19 , besides two unknown by-products (see Fig. and Table 1). The N-methylated (1S)-isoquinoline 5a , on the other hand, afforded largely (S)-orientaline ((S)- 19 ), while an almost equal mixture of (R)-reticuline ( 6b ) and (R)-orientaline ((R)- 19 ) was obtained from the (1R)-enantiomer 5b . The isoquinolines 3a,b and 5a,b were prepared by a Bischler-Napieralski cyclization yielding O-benzyl-protected isoquinoline 10 (Scheme 1). The optical resolution of 10 was accomplished with 2′-bromotartranilic acid. The N-methylated isoquinolines were prepared by N-formylation of 10a,b and reduction of the formamides 13a,b with diborane (→ 14a,b ). Deblocking of the benzyl-ether moieties of 10a,b and 14a,b was accomplished by catalytic hydrogenation in presence of HCl, affording directly 3a,b ·HCl and 5a,b ·HCl, respectively.