Morphological regimes of poly(ε-caprolactone)/octaisobutyl polyhedral oligosilsesquioxane composite films in relation to film composition and thickness

The morphological evolution of poly(ε-caprolactone) (PCL)/octaisobutyl polyhedral oligomeric silsesquioxane (IBUPOSS) films was analyzed using scanning electron microscopy (SEM) and polarized optical microscopy (POM). The morphologies of the blend films with PCL/IBUPOSS mass ratios of 95:5 to 50:50 were discussed according to decomposition mechanism in relation to film composition and thickness. In addition to the morphological regime for films with lower IBUPOSS loadings, in which the growth of PCL spherulites was nearly independent on the presence of fine IBUPOSS aggregates, two new morphological regimes were observed for the films with higher IBUPOSS loadings: (1) thicker blend films exhibited a rich dynamics, giving rise to a trilayer structure and (2) the decomposition of thinner films was induced by the kinetically controlled growth of IBUPOSS aggregates. By varying the thickness and the composition of the blend films, the current study provides important new insight into the rich phase behavior of nanoparticle-filled polymer films.     

Fluorescent CXCR4 chemokine receptor antagonists: metal activated binding

The copper(II) complex of a novel rhodamine-azamacrocycle conjugate binds to the CXCR4 chemokine receptor and competes effectively against anti-CXCR4 monoclonal antibodies. The copper macrocycle unit adopts a trans-II configuration in the solid state.     

Immobilized anthraquinone for redox mediation of horseradish peroxidase for hydrogen peroxide sensing

The detection of hydrogen peroxide is detailed using horseradish peroxidase and anthraquinone. Both species are immobilized on a glassy carbon electrode substrate. This dual immobilization gives rise to lower detection limits compared with the situation when either of the species is immobilized. Detection limits of 40 nM are reported within physiologically-relevant media.     

Strong electron correlation in the decomposition reaction of dioxetanone with implications for firefly bioluminescence

Dioxetanone, a key component of the bioluminescence of firefly luciferin, is itself a chemiluminescent molecule due to two conical intersections on its decomposition reaction surface. While recent calculations of firefly luciferin have employed four electrons in four active orbitals [(4,4)] for the dioxetanone moiety, a study of dioxetanone [F. Liu et al., J. Am. Chem. Soc. 131, 6181 (2009)] indicates that a much larger active space is required. Using a variational calculation of the two-electron reduced-density-matrix (2-RDM) [D. A. Mazziotti, Acc. Chem. Res. 39, 207 (2006)], we present the ground-state potential energy surface as a function of active spaces from (4,4) to (20,17) to determine the number of molecular orbitals required for a correct treatment of the strong electron correlation near the conical intersections. Because the 2-RDM method replaces exponentially scaling diagonalizations with polynomially scaling semidefinite optimizations, we readily computed large (18,15) and (20,17) active spaces that are inaccessible to traditional wave function methods. Convergence of the electron correlation with active-space size was measured with complementary RDM-based metrics, the von Neumann entropy of the one-electron RDM as well as the Frobenius and infinity norms of the cumulant 2-RDM. Results show that the electron correlation is not correctly described until the (14,12) active space with small variations present through the (20,17) space. Specifically, for active spaces smaller than (14,12), we demonstrate that at the first conical intersection, the electron in the σ(?) orbital of the oxygen-oxygen bond is substantially undercorrelated with the electron of the σ orbital and overcorrelated with the electron of the carbonyl oxygen's p orbital. Based on these results, we estimate that in contrast to previous treatments, an accurate calculation of the strong electron correlation in firefly luciferin requires an active space of 28 electrons in 25 orbitals, beyond the capacity of traditional multireference wave function methods.     

Chaotic Expansion of Elements of the Universal Enveloping Algebra of a Lie Algebra Associated with a Quantum Stochastic Calculus

The functional Ito formula, in the form df() = f( + d ) –f(),is formulated and proved in the context of a Lie algebra L associatedwith a quantum (non-commutative) stochastic calculus. Here fis an element of the universal enveloping algebra U of L, andf() + d() – f() is given a meaning using the coproductstructure of U even though the individual terms of this expressionhave no meaning. The Ito formula is equivalent to a chaoticexpansion formula for f() which is found explicitly. 1991 MathematicsSubject Classification: primary 81S25; secondary 60H05; tertiary18B25.     

Hölder-Banach space analysis of the Bethe-Salpeter equation

We find a Hölder Banach space in which the Bethe-Salpeter equation is a compact integral equation as it stands. We study the properties of the solution in preparation for an analysis of linear field theory models of 3-body amplitudes. In particular we study the properties of the Regge poles of the solution and prove the existence and uniqueness of on mass shell scattering amplitudes.     

Palladium-catalyzed carbene insertion into benzyl bromides

Palladium can catalyze the insertion of ethyl diazoacetate into benzyl bromides. The key step in the catalytic cycle is the migratory insertion of a carbene, derived from ethyl diazoacetate, into a Pd-C bond.