Automated generation of contrapuntal musical compositions using probabilistic logic in Derive

In this work, we present a new application developed in Derive 6 to compose counterpoint for a given melody (“cantus firmus”). The result is non-deterministic, so different counterpoints can be generated for a fixed melody, all of them obeying classical rules of counterpoint. In the case where the counterpoint cannot be generated in a first step, backtracking techniques have been implemented in order to improve the likelihood of obtaining a result. The contrapuntal rules are specified in Derive using probabilistic rules of a probabilistic logic, and the result can be generated for both voices (above and below) of first species counterpoint.     

Adhesive interactions of geckos with wet and dry fluoropolymer substrates

Fluorinated substrates like Teflon^® (poly(tetrafluoroethylene); PTFE) are well known for their role in creating non-stick surfaces. We showed previously that even geckos, which can stick to most surfaces under a wide variety of conditions, slip on PTFE. Surprisingly, however, geckos can stick reasonably well to PTFE if it is wet. In an effort to explain this effect, we have turned our attention to the role of substrate surface energy and roughness when shear adhesion occurs in media other than air. In this study, we removed the roughness component inherent to commercially available PTFE and tested geckos on relatively smooth wet and dry fluoropolymer substrates. We found that roughness had very little effect on shear adhesion in air or in water and that the level of fluorination was most important for shear adhesion, particularly in air. Surface energy calculations of the two fluorinated substrates and one control substrate using the Tabor–Winterton approximation and the Young–Dupré equation were used to determine the interfacial energy of the substrates. Using these interfacial energies we estimated the ratio of wet and dry normal adhesion for geckos clinging to the three substrates. Consistent with the results for rough PTFE, our predictions show a qualitative trend in shear adhesion based on fluorination, and the quantitative experimental differences highlight the unusually low shear adhesion of geckos on dry smooth fluorinated substrates, which is not captured by surface energy calculations. Our work has implications for bioinspired design of synthetics that can preferentially stick in water but not in air.     

Contact fault characterisation of complex silicon solar cells: a guideline based on current voltage characteristics and luminescence imaging

Highest efficiency solar cells in industrial and R&D environments are increasingly sensitive to local performance limiting processing faults, which are best characterised by spatially resolved characterisation techniques. This work contains a discussion on the processing faults related to contact resistance and finger interruptions in interdigitated back contact silicon solar cells, which are prime example for a complex cell structure. Using experimental and simulated current–voltage measurements and luminescence images, we explore the strongly non‐linear effect of poor local contact resistances on the global series resistance, fill factor, short circuit current density and efficiency. A good agreement between global and spatially resolved characterisation of faults is found, and potential artefacts are discussed. In conclusion, we present seven cases of contacting faults in interdigitated back contact cells with distinct characteristics that can be identified using a flow chart of experiments. The resulting guideline should assist silicon solar cell manufacturers in localising and quantifying local contacting faults that reduce the cells efficiency in manufacturing of complex solar cells. Copyright © 2015 John Wiley & Sons, Ltd.     

Genetically engineered plasmonic nanoarrays

In the present Letter, we demonstrate how the design of metallic nanoparticle arrays with large electric field enhancement can be performed using the basic paradigm of engineering, namely the optimization of a well-defined objective function. Such optimization is carried out by coupling a genetic algorithm with the analytical multiparticle Mie theory. General design criteria for best enhancement of electric fields are obtained, unveiling the fundamental interplay between the near-field plasmonic and radiative photonic coupling. Our optimization approach is experimentally validated by surface-enhanced Raman scattering measurements, which demonstrate how genetically optimized arrays, fabricated using electron beam lithography, lead to order of ten improvement of Raman enhancement over nanoparticle dimer antennas, and order of one hundred improvement over optimal nanoparticle gratings. A rigorous design of nanoparticle arrays with optimal field enhancement is essential to the engineering of numerous nanoscale optical devices such as plasmon-enhanced biosensors, photodetectors, light sources and more efficient nonlinear optical elements for on chip integration.     

Direct evidence of phospholipids in gecko footprints and spatula–substrate contact interface detected using surface-sensitive spectroscopy

Observers ranging from Aristotle to young children have long marvelled at the ability of geckos to cling to walls and ceilings. Detailed studies have revealed that geckos are ‘sticky’ without the use of glue or suction devices. Instead, a gecko''s stickiness derives from van der Waals interactions between proteinaceous hairs called setae and substrate. Here, we present surprising evidence that although geckos do not use glue, a residue is transferred on surfaces as they walk—geckos leave footprints. Using matrix-free nano-assisted laser desorption-ionization mass spectrometry, we identified the residue as phospholipids with phosphocholine head groups. Moreover, interface-sensitive sum-frequency generation spectroscopy revealed predominantly hydrophobic methyl and methylene groups and the complete absence of water at the contact interface between a gecko toe pad and the substrate. The presence of lipids has never been considered in current models of gecko adhesion. Our analysis of gecko footprints and the toe pad–substrate interface has significant consequences for models of gecko adhesion and by extension, the design of synthetic mimics.     

Evaluation of zinc, cadmium and lead isotope fractionation during smelting and refining

To evaluate metallurgical processing as a source of Zn and Cd isotopic fractionation and to potentially trace their distribution in the environment, high-precision MC-ICP-MS Zn, Cd and Pb isotope ratio measurements were made for samples from the integrated Zn-Pb smelting and refining complex in Trail, B.C., Canada. Significant fractionation of Zn and Cd isotopes during processing of ZnS and PbS ore concentrates is demonstrated by the total variation in δ^66/64Zn and δ^114/110Cd values of 0.42‰ and 1.04‰, respectively, among all smelter samples.No significant difference is observed between the isotopic compositions of the Zn ore concentrates (δ^66/64Zn = 0.09 to 0.17‰; δ^114/110Cd = − 0.13 to 0.18‰) and the roasting product, calcine (δ^66/64Zn = 0.17‰; δ^114/110Cd = 0.05‰), due to ∼ 100% recovery from roasting. The overall Zn recovery from metallurgical processing is ∼ 98%, thus the refined Zn metal (δ^66/64Zn = 0.22‰) is not significantly fractionated relative to the starting materials despite significantly fractionated fume (δ^66/64Zn = 0.43‰) and effluent (δ^66/64Zn = 0.41 to 0.51‰). Calculated Cd recovery from metallurgical processing is 72-92%, with the majority of the unrecovered Cd lost during Pb operations (δ^114/110Cd = − 0.38‰). The refined Cd metal is heavy (δ^114/110Cd = 0.39 to 0.52‰) relative to the starting materials. In addition, significant fractionation of Cd isotopes is evidenced by the relatively light and heavy isotopic compositions of the fume (δ^114/110Cd = − 0.52‰) and effluent (δ^114/110Cd = 0.31 to 0.46‰). In contrast to Zn and Cd, Pb isotopes are homogenized by mixing during processing. The total variation observed in the Pb isotopic compositions of smelter samples is attributed to mixing of ore sources with different radiogenic signatures.     

Cyberbullying in adolescents: Modalities and aggressors’ profile

In this study, a questionnaire (Cyberbullying Questionnaire, CBQ) was developed to assess the prevalence of numerous modalities of cyberbullying (CB) in adolescents. The association of CB with the use of other forms of violence, exposure to violence, acceptance and rejection by peers was also examined. In the study, participants were 1431 adolescents, aged between 12 and17 years (726 girls and 682 boys). The adolescents responded to the CBQ, measures of reactive and proactive aggression, exposure to violence, justification of the use of violence, and perceived social support of peers. Sociometric measures were also used to assess the use of direct and relational aggression and the degree of acceptance and rejection by peers. The results revealed excellent psychometric properties for the CBQ. Of the adolescents, 44.1% responded affirmatively to at least one act of CB. Boys used CB to greater extent than girls. Lastly, CB was significantly associated with the use of proactive aggression, justification of violence, exposure to violence, and less perceived social support of friends.     

A Transient Behaviour in the Initial Production of Aromatic Compounds from Methane Catalyzed by Mo/HZSM-5

The production of aromatic compounds directly from methane using catalysts based on zeolite HZSM-5 impregnated with molybdenum was investigated using a flow reactor at 750 °C. Main products were benzene and naphthalene as well as toluene and others like azulene in smaller amounts. Naphthalene appeared after benzene following an induction period suggesting a consecutive reaction path. A transient behavior in the production of naphthalene was observed along the time on stream, being benzene practically the only product at the steady state. The transient behavior disappeared when increasing contact time, which produced more naphthalene at the expense of benzene.     

Characterisation of Dioscorea bulbifera native starch

A non conventional source of starch, bulbs of Dioscorea bulbifera, was evaluated. Giving a yield of 28.48 g/100 g on dry weight, chemical composition, physical, physico-chemical and morphological characteristics were assessed, as well as its rheological properties. Chemical analysis showed a amylose content of 29.37%. Micrographies showed that most of the starch granules were of irregular shape, similar to a pyramid with rounded vertices, and a smaller number were elongated with smooth surface. Dioscorea starch showed a gelatinization temperature of 70.8 degrees C and maximum viscosity at 88.6 degrees C of 435 Brabender units (BU). It presented a relatively stable consistency to the cooking process and a low tendency to retrogradation; which suggest the starch possible use in food products that need a fast viscosity and a gel with a stable consistency.     

Interpretation of Colloidal Dyeing of Polyester Fabrics Treated with N‐Cetylpyridinium Chloride in Terms of Zeta Potential and Surface Free Energy Balance

In this work are presented results about the effect on the surface free energy and zeta potential for the adsorption process of the colloidal dye Disperse Blue 3 (DBlue3) onto polyester fabric (dacron 54, stile 777), when the fabric is pretreated with N‐cetylpyridinium chloride (NCPCl). The zeta potential of the fabric as a function of the pH of the liquid phase shows that both H⁺ and OH^? ions are involved in determining the potential. The negative charge of the fiber is caused by the presence of the carboxyl end‐groups of the polyester, which are generated by the acidic and basic hydrolysis of the fabric in these media. The zeta potential of the DBlue3 as a function of the pH of the liquid phase shows that the negative charge of the dye particles are because of the presence of an OH^? group, ionized in aqueous media, in the molecular structure of the dye. The zeta potential of the fabric treated with a 10^?3 M solution of NCPCl as a function of the pH of the liquid phase is positive over the whole pH range. This behavior can be attributed to the presence of the pyridinium group in the molecular structure of the surfactant, which is positively charged. The adsorption isotherms of the dye DBlue3 onto a polyester pretreated with NCPCl at 293 K, shows that the presence of the surfactant on the surface of the fabric favors the adsorption of the dye onto the fabric. This fact shows that the pretreatment with NCPCl is a very interesting aspect in the textile industry. On the other hand, the isotherms of the adsorption of the above dye onto the polyester pretreated with a 10^?4 M solution of NCPCl, at different temperatures, shows that the amount of the dye absorbed onto the pretreated fabric increases with the increase in temperature. These behaviors can be justified by the analysis of the components of the surface free energy and zeta potential.

Electron microscopy photographs of the fabric pretreated with NCPCl before (top) and after (bottom) dyeing with DBlue3.