The Inevitability of Fine Tuning in a Complex Universe

Why should the universe need to be fine tuned? The thesis is presented that parameter sensitivity arises as a natural consequence of the mathematics of dynamical systems with complex outcomes. Hence, fine tuning is a mathematical correlate of complexity and should not elicit surprise.     

A Facile Preparation of Highly Substituted ß-Ketoamides

A procedure is described for the preparation of ß-ketoamides by the condensation of ketones and isocyanates under mild conditions.     

Assignment of Anomeric Configuration and Identification of Carbohydrate Residues by 13C NMR: Arabino- and Ribopyranosides and Furancsides

Abstract

A ¹³C NMR fingerprint method previously developed for galactosides and glucosides is extended to arabinosides and ribosides. This approach demonstrates the capability of ¹³C NMR to determine ring size and anomeric configuration in four isomeric arabinosides and ribosides.     

Effect of Mass Transport in the Synthesis of Partially Acetylated Dendrimer: Implications for Functional Ligand-Nanoparticle Distributions

Partial acetylation of the amine-terminated poly(amidoamine) dendrimer has been used in the preparation of dendrimer particles conjugated with a wide variety of functional ligands including targeting moieties, therapeutic agents, and dye molecules. The effectiveness of mass transport during the partial acetylation reaction was found to have a major effect on subsequent distributions of dendrimer-ligand components and to be a major source of inconsistency between batches. This study has broad implications for a wide range of nanoparticle-ligand systems because it demonstrates that conjugates with the same mean ligand-particle ratios can have completely different distribution profiles.     

Catalytic metallodrugs targeting HCV IRES RNA

A catalytic metallodrug that targets stem-loop IIb of the internal ribosomal entry site (IRES) RNA of hepatitis C virus (HCV) demonstrates enzyme-like turnover with K(M) of 0.85 μM, k(cat) of 0.53 min(-1), and a turnover number of 31.9 for Cu·GGHYrFK-amide (1-Cu), and yielded an antiviral activity (IC(50)) of 0.58 μM in an HCV cellular replicon assay.     

Efficient single-photon frequency conversion using a Sagnac interferometer

We propose a scheme for efficient optical frequency conversion at the single-photon power level. The scheme exploits the quantum interference of single-photon states at a three-level quantum emitter coupled to a Sagnac interferometer. We show that this device can achieve single-photon frequency up- or down-conversion with near unity efficiency.     

Nonlinear dynamic buckling of shallow circular arches under a sudden uniform radial load

The structural behavior of a shallow arch is highly nonlinear, and so when the amplitude of the oscillation of the arch produced by a suddenly applied load is sufficiently large, the oscillation of the arch may reach a position at its primary unstable equilibrium path or secondary bifurcation unstable equilibrium path, leading the arch to buckle dynamically. This paper presents an analytical study of the nonlinear dynamic in-plane buckling of a shallow circular arch under a uniform radial load that is applied suddenly and with an infinite duration. The principle of conservation of energy is used to establish the criterion for dynamic buckling of the arch, and the analytical solution for the dynamic buckling load is derived. It is shown that under a suddenly applied uniform radial load, a shallow pinned–fixed arch has a unique possible dynamic buckling load, while shallow pinned–pinned and fixed–fixed arches may have two possible dynamic buckling loads: a lower dynamic buckling load and an upper dynamic buckling load. The dynamic buckling loads of a shallow arch under a suddenly applied uniform radial load with infinite duration are found to be lower than their static counterparts, and to increase with an increase of the arch included angle and slenderness. The effect of static preloading on the dynamic buckling of an arch is also investigated. It is found that the pre-applied static load decreases the dynamic buckling load of the arch, but increases the sum of the pre-applied load and the dynamic buckling load.     

Antibody-functionalized polydiacetylene coatings on nanoporous membranes for microorganism detection

The preparation and characterization of coatings made from polydiacetylene colloids on nano- and microporous membranes and their potential for the detection of microorganisms are presented.     

Eta' photoproduction on the proton for photon energies from 1.527 to 2.227 GeV

Differential cross sections for the reaction gamma p --> eta' p have been measured with the CLAS spectrometer and a tagged photon beam with energies from 1.527 to 2.227 GeV. The results reported here possess much greater accuracy than previous measurements. Analyses of these data suggest for the first time the coupling of the eta'N channel to both the S11(1535) and P11(1710) resonances, known to couple strongly to the etaN channel in photoproduction on the proton, and the importance of J = 3/2 resonances in the process.     

Superoxo, peroxo, and hydroperoxo complexes formed from reactions of rhodium porphyrins with dioxygen: thermodynamics and kinetics

Rhodium(II) porphyrin complexes react with dioxygen to form terminal superoxo and bridged mu-peroxo complexes. Equilibrium constants for dioxygen complex formation with rhodium(II) tetramesitylporphyrin ((TMP)Rh*) and a m-xylyl-tethered dirhodium(II) diporphyrin complex (*Rh(m-xylyl)Rh*) are reported. (TMP)Rh-H reacts with oxygen to form a transient hydroperoxy complex ((TMP)Rh-OOH), which reacts on to form the rhodium(II) complex ((TMP)Rh*) and water. Kinetic studies for reactions of (TMP)Rh-H with O2 suggest a near concerted addition of dioxygen to the (TMP)Rh-H unit. Reactivity studies for mixtures of H2/O2 and CH4/O2 with the dirhodium(II) complex (*Rh(m-xylyl)Rh*) are reported.