Towards a characterization of generalized twisted field planes

In this work we study semifield planes of orderq ⁿ(q=p ^r ,p prime) with a collineation whose order is ap-primitive divisor ofq ⁿ–1.Research supported in part by NSF Grant No. DMS-9107372Research supported in part by NSF grants RII-9014056, component IV of the EPSCoR of Puerto Rico grant and ARO grant for Cornell MSI.     

R-Matrices for Leibniz Algebras

Leibniz agebras are a generalization of Lie algebras, where no symmetry properties of the bracket are required. In this Letter we introduce a notion of R-matrices for this structure and the related Yang–Baxter equations, and discuss some of their basic properties.     

Influence of Morphological Homogeneity of Superspherical Gold Nanoparticles on Plasmonic Photothermal Heat Generation

The plasmonic photothermal (PPT) characteristics of gold nanostructures have been extensively investigated theoretically and experimentally due to their potential for use materials science and industry. The management of the size and shape of gold nanoparticles has been a key issue in the development of better solutions for PPT heat generation because their size and shape determine their resultant photothermal properties. However, the light absorption of gold nanostructures is mainly dependent on the wavelength and orientation of the incident light; hence, maintaining uniform size and shape is critical for achieving maximum photothermal energy. Morphologically homogeneous spherical gold nanoparticles, or super gold nanospheres prepared by slowly etching uniform octahedral gold nanoparticles, demonstrate better PPT heat generation compared with commercially available nonsmooth gold nanoparticles (GNSs). The PPT heating experiments show a maximum temperature difference of 5.7 °C between the super and ordinary GNSs with the same average maximum Feret's diameters, which result from the more efficient PPT heat power generation (20.6%) of the super GNSs. In an electromagnetic‐wave simulation, the super GNSs show lower polarization dependence and a 24.6% higher absorption cross‐section than ordinary GNSs.     

Collision of a Solid with an Incompressible Fluid

We give a predictive theory of the collisions of a viscous incompressible fluid with solids. The theory is based on interior percussions which account for the very large stresses and contact forces resulting from the kinematic incompatibilities responsible for the collision. New equation of motion and constitutive laws result from the theory. Examples dealing with a fluid colliding with its container and with a diver impacting the water of a swimming pool are studied.     

Two-photon fluorescent probes for long-term imaging of calcium waves in live tissue

2-Acetyl-6-(dimethylamino)naphthalene-derived two-photon fluorescent Ca2+ probes (ACa1-ACa3) are reported. They can be excited by a 780 nm laser beam, show 23-50-fold enhancement in one- and two-photon excited fluorescence in response to Ca2+, emit fourfold stronger two-photon excited fluorescence than Oregon Green 488 BAPTA-1 upon complexation with Ca2+, and can selectively detect intracellular free Ca2+ ions in live cells and living tissues with minimum interference from other metal ions and membrane-bound probes. Moreover, these probes are capable of monitoring calcium waves at a depth of 120-170 microm in live tissues for 1100-4000 s using two-photon microscopy with no artifacts of photobleaching.     

Co/C-catalyzed tandem carbocyclization reaction of 1,6-diynes

Cobalt on charcoal (Co/C) can be used as a catalyst in the tandem carbocycloaddition reaction of 1,6-diyne and carbon monoxide. The reaction product is dependent upon the reaction temperature, the position of the functional group, and the substrate itself.