A composite Bayesian hierarchical model of compositional data with zeros

We present an effective approach for modelling compositional data with large concentrations of zeros and several levels of variation, applied to a database of elemental compositions of forensic glass of various use types. The procedure consists of the following: (i) partitioning the data set in subsets characterised by the same pattern of presence/absence of chemical elements and (ii) fitting a Bayesian hierarchical model to the transformed compositions in each data subset. We derive expressions for the posterior predictive probability that newly observed fragments of glass are of a certain use type and for computing the evidential value of glass fragments relating to two competing propositions about their source. The model is assessed using cross‐validation, and it performs well in both the classification and evidence evaluation tasks. Copyright © 2014 John Wiley & Sons, Ltd.     

Water effects on electron transfer in azurin dimers

Recent experimental and theoretical analyses indicate that water molecules between or near redox partners can significantly affect their electron-transfer (ET) properties. Here, we study the effects of intervening water molecules on the electron self-exchange reaction of azurin (Az) by using a newly developed ab-initio method to calculate transfer integrals between molecular sites. We show that the insertion of water molecules in the gap between the copper active sites of Az dimers slows down the exponential decay of the ET rates with the copper-to-copper distance. Depending on the distance between the redox sites, water can enhance or suppress the electron-transfer kinetics. We show that this behavior can be ascribed to the simultaneous action of two competing effects: the electrostatic interaction of water with the protein subsystem and its ability to mediate ET coupling pathways.     

Asymmetric Michael addition promoted by (R,R)-trans-1,2-diaminocyclohexane in ionic liquids

In tetrafluoroborate based ionic liquids fair yields and enantiomeric excesses up to 91% were obtained in the Michael addition of ethyl cyclohexanone-2-carboxylate to methyl vinyl ketone, using (R,R)-trans-1,2-diaminocyclohexane as chiral auxiliary (37% mol/mol with respect to the donor). The presence of catalytic amounts of metal sources [Ni(OAc)₂ · 4H₂O, Co(acac)₂, FeCl₃ · 6H₂O, LaCl₃, Cu(OAc)₂ · H₂O] did not improve the activity, and, in some instances, caused a drop of enantioselectivity. Reactions carried out in the absence of any metal and with a Michael donor/diamine molar ratio of 20 allowed us to ascertain that the reaction can be performed catalytically.     

Random terpolymers for electroluminescent devices: Synthesis and characterization of new cyano‐containing poly(fluorenylene‐vinylene)s

The synthesis of new random poly(2,7‐fluorenylene‐vinylene)s was achieved by a Suzuki–Heck cascade polymerization reaction. The poly(fluorenylene‐vinylene) base structure was modified by the regio‐random incorporation of 1‐cyano‐2,5‐phenylene as electron withdrawing unit ( CN‐PFV1 ) and its properties were compared with terpolymers also embodying 1,4‐dioctyloxy‐2,5‐phenylene ( CN‐PFV2 ) or 3,6‐N‐octylcarbazole ( CN‐PFV3 ) as electron‐donating moieties. Thermal analysis revealed a high thermal stability (T_d > 389 °C) and the absence of glass transitions for all polymers. Cyclic voltammetry indicated a high electron affinity of the materials (2.96–3.21 eV) attributed to the presence of the cyano‐containing comonomer. In dilute solutions, the copolymers showed a broad green fluorescence with quantum yields ranging from 0.42 to 0.79, while in the solid state, a relatively narrow emission centered at ～ 560 nm, governed by the low‐energy segments within the π‐conjugated backbone, was observed. The electroluminescence properties of the materials were tested in OLED devices of ITO/PEDOT‐PSS/ CN‐PFV1‐3 /Ca/Al or ITO/PEDOT‐PSS/ CN‐PFV1‐3 /Alq₃/Ca/Al configurations, showing a bright green‐yellow emission that, in the case of CN‐PFV2 , reached 1403 cd/m² with efficiencies as high as 0.13 cd/A. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6051–6063, 2008     

Evidence of non-statistical structures in the elastic and inelastic scattering of58Ni+58Ni and58Ni+62Ni and intermediate dinuclear states

Excitation functions and angular distributions of⁵⁸Ni+⁵⁸Ni and⁵⁸Ni+⁶²Ni scattering at energies just above the Coulomb barrier have been measured aroundθ _cm=90° in energy stepsΔE _cm=0.25 MeV fromE _cm ? 110 MeV toE _cm ? 120 MeV for⁵⁸Ni+⁵⁸Ni and fromE _cm ? 110 MeV toE _cm ? 118 MeV for⁵⁸Ni+⁶²Ni. Evidence for structure of non-statistical character has been found in the angle-summed excitation functions; this evidence is corroborated by the analysis of the angular distributions. This is the first time that non-statistical structure in elastic and inelastic scattering is reported with high confidence level for this mass and excitation energy ranges. Attempts are presented to understand the nature of this structure, including the presence of intermediate dinuclear states and virtual states in a potential well.     

A systematic investigation of the role of material parameters in metastability of hydrogenated amorphous silicon

In this work, the role of structural, electronic and optical parameters of as-deposited amorphous silicon films in photoconductivity decay during light soaking was systematically investigated. Deposition temperature was varied in the range 130–270°C, in order to obtain samples with different structural, optical and electronic properties. As a result, two degradation regimes were identified. At short illumination times (within a few days in typical samples, and within a few hours in the low quality samples), the material showed different tendency to degradation depending on the content of the SiH bond clusters. At long illumination times, in all the light soaked samples the photoconductivity decay followed the t^−1/3 law. The measured photoconductivity degradation was simulated starting from the bond-breaking model. The observed correlation between the material structural parameters and the different tendencies to degradation is explained in terms of variations of the Staebler-Wronski susceptibility.     

Calix[4]arene-cholic acid conjugates: a new class of efficient synthetic ionophores

The synthesis of a new class of amphiphilic calix[4]arene-based ionophores, relying on direct reductive amination as a key step, and the evaluation of their H+ and Na+ transporting properties is described.     

Preheat effects on shock propagation in indirect-drive inertial confinement fusion ablator materials

The velocities and temperatures of shock waves generated by laser-driven hohlraum radiation fields have been measured for several indirect-drive inertial confinement fusion capsule ablator materials. For the first time, a time-resolved measurement of the preheat temperature ahead of the shock front has been performed and included in the analysis. It is found that preheat ahead of the shock front can cause significant shock propagation variations in the ignition capsule ablator materials being considered for the National Ignition Facility (NIF). If unaccounted for, these preheat effects could potentially preclude ignition at the NIF.     

(Co)bordism Groups in Quantum PDEs

In this paper we formulate a theory of noncommutative manifolds (quantum manifolds) and for such manifolds we develop a geometric theory of quantum PDEs (QPDEs). In particular, a criterion of formal integrability is given that extends to QPDEs previously obtained by D. C. Spencer and H. Goldschmidt for PDEs for commutative manifolds, and by Prástaro for super PDEs. Quantum manifolds are seen as locally convex manifolds where the model has the structure A ^m _{1 1}×···×A ^m _{s s} , with AA ₁×···×A _s a noncommutative algebra that satisfies some particular axioms (quantum algebra). A general theory of integral (co)bordism for QPDEs is developed that extends our previous for PDEs. Then, noncommutative Hopf algebras (full quantum p-Hopf algebras, 0pm–1) are canonically associated to any QPDE, Ê_k ^k _m(W) whose elements represent all the possible invariants that can be recognized for such a structure. Many examples of QPDEs are considered where we apply our theory. In particular, we carefully study QPDEs for quantum field theory and quantum supergravity. We show that the corresponding regular solutions, observed by means of quantum relativistic frames, give curvature, torsion, gravitino and electromagnetic fields as A-valued distributions on spacetime, where A is a quantum algebra. For such equations, canonical quantizations are obtained and the quantum and integral bordism groups and the full quantum p-Hopf algebras, 0p3, are explicitly calculated. Then, the existence of (quantum) tunnel effects for quantum superstrings in supergravity is proved.     

On the geometric realization of Albanese's inequality

If an algebraic curve C (irreducible and reduced) moving in a family in projective n-space specializes into a curve C ₀, having associated cycle Z=m ₁ B ₁+···+m _r B _r , then the geometric genera g, g ₁,....,g _r of C, B ₁,...,B _r respectively and the coefficients m ₁,...,m _r must satisfy a certain inequality (found by Albanese). The realization (or existence) problem asks whether an inequality of this type actually arises from an algebraic family of curves. In this paper some results are obtained concerning the strong version of the problem, where one specifies the cycle Z; with these an affirmative solution of the weak version (where the components B _i are not specified) is obtained.