One-pot synthesis of hybrid TiO2-polyaniline nanoparticles by self-catalyzed hydroamination and oxidative polymerization from TiO2-methacrylic acid nanoparticles

A simple self-catalyzed hydroamination method for creating hybrid TiO(2)-polyaniline core-shell nanoparticles (NP) has been shown. Hybrid NPs with a range of possible sizes are afforded in high yield under mild reaction conditions and simultaneously show improved charge transport and electrochromic behavior compared to either polyaniline alone or physically blended with TiO(2).     

Four-digit numbers which are squared sums

There is a very natural way to divide a four-digit number into 2 two-digit numbers. Applying an algorithm to this pair of numbers, determine how often the original four-digit number reappears.     

Rhodium(II) Metallopeptide Catalyst Design Enables Fine Control in Selective Functionalization of Natural SH3 Domains

Chemically modified proteins are increasingly important for use in fundamental biophysical studies, chemical biology, therapeutic protein development, and biomaterials. However, chemical methods typically produce heterogeneous labeling and cannot approach the exquisite selectivity of enzymatic reactions. While bioengineered methods are sometimes an option, selective reactions of natural proteins remain an unsolved problem. Here we show that rhodium(II) metallopeptides combine molecular recognition with promiscuous catalytic activity to allow covalent decoration of natural SH3 domains, depending on choice of catalyst but independent of the specific residue present. A metallopeptide catalyst succeeds in modifying a single SH3‐containing kinase at endogenous concentrations in prostate cancer (PC‐3) cell lysate.     

Particle capture via discrete binding elements: systematic variations in binding energy for randomly distributed nanoscale surface features

This work examines how the binding strength of surface-immobilized "stickers" (representative of receptors or, in nonbiological systems, chemical heterogeneities) influences the adhesion between surfaces that are otherwise repulsive. The study focuses on a series of surfaces designed with fixed average adhesive energy per unit area and demonstrates quantitatively how a redistribution of the adhesive functionality into progressively larger clusters (stronger stickers) increases the probability of adhesive events. The work employs an electrostatic model system: relatively uniform, negative 1 μm silica spheres flow gently over negative silica flats. The flats contain small amounts of randomly positioned nanoscale cationic patches. The silica-silica interaction is repulsive; however, the cationic patches (present at sufficiently low levels that the overall surface charge remains substantially negative) produce local attractions. In this study, the attractions are relatively weak so that multiple patches engage to capture flowing particles. Experiments reveal an adhesion signature characteristic of a renormalized random distribution when the sticker strength is increased at an overall fixed binding strength per unit area of surface. The form of the particle capture curves are in good quantitative agreement with a simple model that assumes only a fixed adhesion energy needed for particle capture. Aside from the quantitative details that provide a simple formalism for anticipating particle adhesion, this work demonstrates how increasing the heterogeneities in the surface functionality can cause a system to go from being nonadhesive to becoming strongly adhesive. Indeed, systems containing small amounts of discretized adhesive functionality are always more adhesive than systems in which the same functionality is distributed uniformly over the surface (the mean field scenario).     

Extended-chain crystals

Summary The morphology of extended chain lamellae and fibrous polytetrafluoroethylene has been analyzed by electron microscopy and compared to polyethylene. The crystal growth mechanism of initial folding on molecular nucleation followed by chain extension is applicable to both polymers and seems to be a general mechanism for crystallization of prepolymerized linear macromolecules. Differences arise from the branching mechanism of the spherulites. Annealing the striated surface created on fracture could be shown to lead to folded chain ripples of time and temperature dependent thickness. Fibrous crystals of smooth and shish-kebob-type appearance were grown from gaseous tetrafluoroethylene.

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Zusammenfassung Die Morphologie der extended chain-Lamellen und von faserigem Polytetrafluoräthylen wird elektronenmikroskopisch analysiert und mit Polyäthylen verglichen. Der Kristallwachstumsmechanismus anfänglicher Faltung bei molekularer Nukleation, gefolgt von Streckung der Ketten, kann auf beide Polymere angewendet werden und scheint ein allgemeiner Mechanismus der Kristallisation von polymerisierten linearen Makromolekülen zu sein. Unterschiede entstehen vom Verzweigungsmechanismus bei den Sphärolithen. Tempern der gestreiften Bruchflächen — so ließ sich zeigen-führt zu Riffeln von gefalteten Ketten mit zeit- und temperaturabhängigen Dicken. Faserige Kristalle vom glatten und vom Schaschlik-Typ wachsen von gasförmigem Polytetrafluoräthylen.

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For part I–VI of this series see J. Polymer Sci., Part A2, 2043–2113 (1969), Part VII, J. Polymer Sci., Part B,10, 57 (1972).

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Dedicated to ProfessorR. Hosemann on the occasion of his 60th birthday.     

Continuity properties of majority rule with intermediate preferences

This paper shows that certain conditions which have previously been shown (by Grandmont) to be sufficient for a society's majority rule relation to be transitive or acyclic are also sufficient for the map from distributions of voter preferences to indices identified with their majority rule relations to be continuous. Applications of this result to societies with certain classical assumptions on preferences reveal that, in such societies, the map from distributions of voter preferences to their majority rule equilibria is also continuous.     

Social utility functions for strategic decisions in probabilistic voting models

This paper studies societies which have probabilistic voting that is smooth, scalable and unbiased. Its results establish that, in such societies, the decisions of vote-seeking candidates who start at a common location (such as the status quo for the society's policies and/or the same allocation of campaign resources) contain implicit rationality properties. In particular, it shows that in every such society there exist social utility functions which simultaneously rationalize the directional Nash behavior of candidates, the stationary electoral equilibria, and the non-degenerate local electoral equilibria which can occur at these locations. This is shown to be true both for unconstrained and for constrained sets of possible candidate locations. An example of such a utility function (which occurs in every one of the societies under consideration) is also provided.     

Vowel perception by noise masked normal-hearing young adults

This study examined vowel perception by young normal-hearing (YNH) adults, in various listening conditions designed to simulate mild-to-moderate sloping sensorineural hearing loss. YNH listeners were individually age- and gender-matched to young hearing-impaired (YHI) listeners tested in a previous study [Richie et al., J. Acoust. Soc. Am. 114, 2923-2933 (2003)]. YNH listeners were tested in three conditions designed to create equal audibility with the YHI listeners; a low signal level with and without a simulated hearing loss, and a high signal level with a simulated hearing loss. Listeners discriminated changes in synthetic vowel tokens /I e epsilon alpha ae/ when Fl or F2 varied in frequency. Comparison of YNH with YHI results failed to reveal significant differences between groups in terms of performance on vowel discrimination, in conditions of similar audibility by using both noise masking to elevate the hearing thresholds of the YNH and applying frequency-specific gain to the YHI listeners. Further, analysis of learning curves suggests that while the YHI listeners completed an average of 46% more test blocks than YNH listeners, the YHI achieved a level of discrimination similar to that of the YNH within the same number of blocks. Apparently, when age and gender are closely matched between young hearing-impaired and normal-hearing adults, performance on vowel tasks may be explained by audibility alone.