Viscosity of confined inhomogeneous nonequilibrium fluids

We use the nonlocal linear hydrodynamic constitutive model, proposed by Evans and Morriss [Statistical Mechanics of Nonequilibrium Liquids (Academic, London, 1990)], for computing an effective spatially dependent shear viscosity of inhomogeneous nonequilibrium fluids. The model is applied to a simple atomic fluid undergoing planar Poiseuille flow in a confined channel of several atomic diameters width. We compare the spatially dependent viscosity with a local generalization of Newton's law of viscosity and the Navier-Stokes viscosity, both of which are known to suffer extreme inaccuracies for highly inhomogeneous systems. The nonlocal constitutive model calculates effective position dependent viscosities that are free from the notorious singularities experienced by applying the commonly used local constitutive model. It is simple, general, and has widespread applicability in nanofluidics where experimental measurement of position dependent transport coefficients is currently inaccessible. In principle the method can be used to predict approximate flow profiles of any arbitrary inhomogeneous system. We demonstrate this by predicting the flow profile for a simple fluid undergoing planar Couette flow in a confined channel of several atomic diameters width.     

Synthesis of sodium tantalate nanorods by alkalide reduction

NaTaO3 nanorods were synthesized with high (>90%) yield by reduction of TaCl5 with THF solutions of the alkalide K+(15C5)2Na-, followed by product annealing under dynamic vacuum at 250 and 600 degrees C. In addition to the nanorods, the product is comprised of 5-10% approximately 10-nm diameter spheroidal NaTaO3 nanocrystals. The nanorods are generally longer than 500 nm, with some exceeding 1 mum, and 10-100 nm wide, with aspect ratios that vary between 10 and 20:1. Select area electron diffraction patterns of individual nanorods indicate that each nanorod is a single crystal with its axis oriented in the [010] direction.     

Synthesis of the methanesulfonates of α-(4-chlorophenyl)-α-[1-(2-chlorophenyl)emenyl]-1H-1,2,4-triazole-1-ethanol and α-[1-(2-chlorophenyl)ethenyl]-α-(2,4-difluorophenyl)-1H-1,2,4-triazole-1-ethanol,alpha styryl carbinol antifungal agents

The methanesulfonates of (α-(4-chlorophenyl)-α-[1-(2-chlorophenyl)ethenyl]-1H-1,2,4-triazole-1-ethanol and α-[1-(2-chlorophenyl)ethenyl]-α-(2,4-difluorophenyl)-1H-1,2,4-triazole-1-ethanol ( 1a, b ) are orally effective α-styryl carbinol derivatives developed for the treatment and prevention of systemic fungal infections. Practical new processes amenable for the large-scale production of these compounds are described. Of note is the selection of dichlorostyrene as a convenient precursor of the styryl portion, modification of a sensitive Grignard addition into a realistic preparative reaction and the use of 1,2,4-triazole simultaneously as a base transfer agent and nucleophile.     

Caged Thiophosphotyrosine Peptides

No Abstract     

Efficient synthesis of 4-aminoquinazoline and thieno[3,2-d]pyrimidin-4-ylamine derivatives by microwave irradiation

[reaction: see text] A simple, efficient, and high-yielding synthesis of quinazolin-4-ylamine and thieno[3,2-d]pyrimidin-4-ylamine derivatives is reported under microwave irradiation conditions. Reaction conditions including temperature, solvent, and reaction time have been studied. An efficient parallel workup procedure was developed to generate a small library (23 compounds) in a short time period.     

Spongistatin synthetic studies. An efficient, second-generation construction of an advanced ABCD intermediate

[reaction: see text] A short, efficient, and stereocontrolled synthesis of (-)-4, an advanced ABCD subunit of the spongistatins, has been achieved. Central to the synthetic strategy is the multicomponent linchpin union of silyl dithianes with epoxides to access both the AB and CD fragments. Fragment coupling was then achieved via an efficient stereoselective aldol reaction. The linear sequence required 22 steps and proceeded in 4.0% overall yield.