New Synthesis of Acetaminophen Derivatives Containing a Phosphorus Atom

Two derivatives of acetaminophen have been efficiently prepared from 4-aminophenol via a two-step procedure involving acetylation of OH and NH ₂ groups and then the reaction of the acetylated compounds with diakyl acetylenedicarboxylate in the presence of triphenylphosphine. The products were obtained in good yields.     

Large core-shell poly(methyl methacrylate) colloidal clusters: synthesis, characterization, and tracking

We present a multistep procedure yielding large (diameter > 2 μm) monodisperse, fluorescently labeled core-shell poly(methyl methacrylate) (PMMA) latex particles via dispersion polymerization. The particles' physical properties were controlled by adjusting two reaction parameters, the initiator and chain transfer agent concentrations, which influence the molecular weight of the PMMA. Under certain conditions, particles with the requisite properties for fabricating colloidal clusters were synthesized. The resulting clusters represent a new type of nonspherical colloid that can be dispersed in a density- and refractive index-matching solvent, making them ideal for quantitative studies using confocal microscopy. To demonstrate the utility of our clusters, we measured the translational and rotational diffusion coefficients of a tetrahedral cluster by tracking the motion of its constituent particles in three-dimensional space. More broadly, our findings provide new insights concerning PMMA dispersion polymerization in apolar media.     

Heavy quarks in the presence of higher derivative corrections from AdS/CFT

We use the gauge–string duality to study heavy quarks in the presence of higher derivative corrections. These corrections correspond to the finite-coupling corrections on the properties of heavy quarks in a hot plasma. In particular, we study the effects of these corrections on the energy loss and the dissociation length of a quark–antiquark pair. We show that the calculated energy loss of heavy quarks through the plasma increases. We also find in general that the dissociation length becomes shorter with the increase of coupling parameters of higher curvature terms.     

Some Finiteness Results for Local Cohomology Modules with Respect to a Pair of Ideals

Mathematical Notes - Suppose that $$R$$ is a commutative Noetherian ring with identity, $$I$$ , $$J$$ are ideals of $$R$$ , and let $$M$$ be a finitely generated $$R$$ -module. Let $$H^i_{I,J}(-)$$...     

Modeling semiconductor devices by using Neuro Space Mapping

In this paper a new method for modeling semiconductor devices by use of the drift-diffusion (DD) model and neural networks is presented. Unlike the hydrodynamic (HD) model which is complicated, time consuming with high processing cost, the proposed method has lower complexity and lower simulation time. In this method the RBF neural network has been used for correcting parameters in the drift-diffusion model. Therefore solving approximate model (DD) causes to obtain accurate response. The proposed method is first applied to a silicon n-i-n diode in one dimension, and then to a silicon thin-film MOSFET in two-dimensions, both for interpolation and extrapolation. The obtained results for basic variables, i.e., electron and potential distribution for different voltages, confirm the high efficiency of the proposed method.