Acceleration of acid-catalyzed transesterification of 2-hydroxypropyl-p-nitrophenyl phosphate by organic solvents

[structure: see text] Transesterification of 2-hydroxypropyl-p-nitrophenyl phosphate in the presence of 0.092 M HClO4 is 50-5000 times faster in acetonitrile, 1,4-dioxane, methanol, ethanol, N,N-dimethylformamide, or dimethyl sulfoxide than in water. This demonstrates the importance of tuning the microenvironments in designing synthetic nucleases.     

Real minimal hypersurfaces in complex two-plane Grassmannians

We give a pinching condition for compact minimal hypersurfaces in complex two-plane Grassmannians G ₂(? ^m+2) in terms of sectional curvature and the squared norm of the shape operator.     

Some Conditions on Real Hypersurfaces in Quaternionic Projective Spaces in Terms of Lie Derivatives

The purpose of this paper is to give a non-existence property with the Lie derivative of the structure tensors φ _i and some characterizations of real hypersurfaces of type A ₁, A ₂ in a quaternionic projective space QP ^m in terms of the Lie derivatives of the second fundamental tensor A and the induced Riemannian metric g on the distribution D ^⊥ = Span {U ₂, U ₂, U ₃}. This revised version was published online in June 2006 with corrections to the Cover Date.     

Numerical simulation of turbulence transition and sound radiation for flow through a rigid glottal model

Large eddy simulation (LES)-based computational aeroacoustics techniques were applied to a static model of the human glottis, idealized here as a planar channel with an orifice, to study flow-acoustic interactions related to speech. Rigid models of both converging and diverging glottal passages, each featuring a 20 deg included angle and a minimal glottal diameter of 0.04 cm, with an imposed transglottal pressure of 15 cm H2O, were studied. The Favre-filtered compressible Navier-Stokes equations were integrated for this low-Mach-number flow using an additive semi-implicit Runge-Kutta method and a high-order compact finite-difference scheme with characteristic-based nonreflecting boundary conditions and a multiblock approach. Flow asymmetries related to the Coanda effect and transition to turbulence, as well as the far-field sound, were captured. Acoustic-analogy-based far-field sound predictions were compared with direct simulations and showed that dipole sources, arising from unsteady flow forces exerted on the glottal walls, are primarily responsible for the tonal sound observed in the divergent glottis case.     

Interplay between carrier and impurity concentrations in annealed Ga1-xMnxAs: intrinsic anomalous hall effect

Investigating the scaling behavior of annealed Ga1-xMnxAs anomalous Hall coefficients, we note a universal crossover regime where the scaling behavior changes from quadratic to linear. Furthermore, measured anomalous Hall conductivities in the quadratic regime when properly scaled by carrier concentration remain constant, spanning nearly a decade in conductivity as well as over 100 K in T_[C] and comparing favorably to theoretically predicated values for the intrinsic origins of the anomalous Hall effect. Both qualitative and quantitative agreements strongly point to the validity of new equations of motion including the Berry phase contributions as well as the tunability of the anomalous Hall effect.