Geometrical Monte Carlo model of liquid-phase sintering

Liquid-phase sintering (LPS) is an industrial process used to consolidate materials composed of two different kinds of metallic and/or ceramic powders. At constant temperature, the amount of the present liquid-phase is constant. However, the shape of particles of solid phase changes over time. In general, the rounding of particles and the growth of big particles at the expense of the small ones are observed. This process is known as Ostwald ripening.     

Microstructure and mineralogy of lightweight aggregates produced from washing aggregate sludge,fly ash and used motor oil

The microstructures and mineralogical compositions of lightweight aggregates (LWAs) manufactured with washing aggregate sludge (WS), fly ash (FA) and used motor oil (UMO) have been studied. Most LWAs with WS and FA exhibited an external layer and a glassy core with isolated pores. LWAs with WS and UMO did not present external shells or signs of bloating. Iron oxides, within the external layer, and pyrrhotite, in the inner glass, were observed. The mineralogical analyses revealed the neo-formation of plagioclase and pyroxene, along with minor gehlenite. Some relationships could be established: (i) the presence of larger pores is related to a decrease in the dry particle density values, (ii) when the LWA lacks the external layer, the water absorption values were dependent on the size and amount of each type of pore (open or closed), and (iii) the neo-formation of Ca-plagioclase and the consumption of quartz improved the compressive strength values.     

Reaction of p-Hydroxycinnamyl Alcohols with Transition Metal Salts. 2. Preparation of Guaiacyl/Syringyl Di-, Tri-, and Tetralignols

Treatment of coniferyl alcohol (CA), sinapyl alcohol (SA), and their mixtures with copper or manganese salts yielded nine dilignols, five trilignols, and one tetralignol. The lignols were composed of guaiacyl (G) or CA units and syringyl (S) or SA units linked together by β-O-4 (b), β-5 (c for coumaran), β–β (r for resinol), and/or a novel γ-β (gb) linkage. None of the isolated lignols contained 5–5′ (biphenyl), 4-O-5, or β-1 linkages. Spectral analysis (¹H NMR, ¹³C NMR, MS) and comparison with authentic compounds confirmed the structures of the dilignols as G-b-CA, G-b-SA, S-b-CA, S-b-SA, G-c-CA, S-c-CA, G-r-G, G-r-S, and S-r-S; the trilignols as G-b-S-r-S, G-b-S-c-CA, S–b-S-r-S, and G-c-G-gb-G; and the only tetralignol as G-b-S-r-S-b-G.     

Scaling and universality in the human voice

Speech is a distinctive complex feature of human capabilities. In order to understand the physics underlying speech production, in this work, we empirically analyse the statistics of large human speech datasets ranging several languages. We first show that during speech, the energy is unevenly released and power-law distributed, reporting a universal robust Gutenberg–Richter-like law in speech. We further show that such ‘earthquakes in speech’ show temporal correlations, as the interevent statistics are again power-law distributed. As this feature takes place in the intraphoneme range, we conjecture that the process responsible for this complex phenomenon is not cognitive, but it resides in the physiological (mechanical) mechanisms of speech production. Moreover, we show that these waiting time distributions are scale invariant under a renormalization group transformation, suggesting that the process of speech generation is indeed operating close to a critical point. These results are put in contrast with current paradigms in speech processing, which point towards low dimensional deterministic chaos as the origin of nonlinear traits in speech fluctuations. As these latter fluctuations are indeed the aspects that humanize synthetic speech, these findings may have an impact in future speech synthesis technologies. Results are robust and independent of the communication language or the number of speakers, pointing towards a universal pattern and yet another hint of complexity in human speech.     

Continuous ultrasound-assisted extraction coupled to flow injection-pervaporation, derivatization, and spectrophotometric detection for the determination of ammonia in cigarettes

A dynamic system for the continuous removal of ammonia from cigarettes with ultrasound assistance and iterative change of the flow direction of the extractant through the sample cell has been developed. A 0.1-g sample of cigarette was subjected to 7 min of ultrasound-assisted extraction (application and duration of pulse 0.7 s, output amplitude 85% of the converter nominal amplitude), and 1 M NaOH solution was used both as extractant and as carrier in the dynamic system. The ultrasound-assisted extractor was coupled to a pervaporation unit through a flow injection interface in order to develop a fully automated method. In arriving at the pervaporator, the ammonia is transferred from the donor-carrier stream to an acceptor stream, where the classical Berthelot reaction takes place--thus favoring pervaporation. The blue complex formed is spectrophotometrically monitored at 655 nm. The method was applied to the determination of ammonia in a selection of 10 European cigarette brands and Kentucky Reference 2R4F cigarettes.     

Analytical investigation of the interactions between SC3 hydrophobin and lipid layers: elaborating of nanostructured matrixes for immobilizing redox systems

Hydrophobins are highly tensioactive fungal proteins with a pronounced affinity for interfaces and a propensity for self-assembly. Recently, these proteins were shown to be useful in retaining different molecules on solid surfaces. This finding offers a possibility for developing new functional materials, while creating the necessity of further research at a deeper mechanistic level. In this work, the mechanisms governing the surface phenomena were studied using native Schizophyllum commune hydrophobin (SC3) and lipid mono- and bilayers; the soft matter systems were used to get a handle on the interactive protein/interface effects at a molecular level. The results obtained indicated that the SC3/lipid membrane interactions were adjusted by protein conformational adaptation, allowing its incorporation into lipid matrixes; the incorporation of a chelating SC3 hydrophobin (PFA-SC3) in a monoolein cubic phase yielded a biomimetic, cell-like system of Cu(II) cation immobilization. This system, which is suitable for modifying electrode surface and monitoring the Cu(II)/Cu(0) redox process, may be of practical interest in switching and sensing.     

PDMS microdevice for precise liquid aspiration in the submicroliter range based on the Venturi effect

This paper presents the study of a MEMS (microelectromechanical systems) precision aspiration device designed to extract liquids from a reservoir, which could be an animal or human body. The device works by generating a negative pressure, which deflects a membrane and extracts liquid volumes in the submicroliter range. This negative pressure is created inside a closed channel using the Venturi effect. The existence of the membrane prevents the extracted fluid to be mixed or in contact with the actuation fluid, avoiding cross-contamination of the samples. In addition, the microdevice is pneumatically actuated using air, preventing damages in the extracted volumes because of electric fields and minimizing the actuation cost because inert gas sources are not necessary. The device is fabricated in poly-dimethyl-siloxane (PDMS) using an inexpensive fabrication process. A study has been made to determine the influence of several geometrical parameters over the operation. Finally, experiments demonstrate the working of the device providing an aspiration range from 20 to 120 nL with an average sensitivity of extracted volume with respect to actuation pressure of 220 pL/mbar.     

Web Accessibility Evaluation Tools: A Survey and Some Improvements

Web Content Accessibility Guidelines (WCAG) from W3C consist of a set of 65 checkpoints or specifications that Web pages should accomplish in order to be accessible to people with disabilities or using alternative browsers. Many of these 65 checkpoints can only be checked by a human operator, thus implying a very high cost for full evaluation. However, some checkpoints can be automatically evaluated, thus spotting accessibility barriers in a very effective manner. Well known tools like Bobby, Tawdis or WebXACT evaluate Web accessibility by using a mixture of automated, manual and semiautomated evaluations. However, the automation degree of these Web evaluations is not the same for each of these tools. Since WCAG are not written in a formalized manner, these evaluators may have different “interpretations” of what these rules mean. As a result, different evaluation results might be obtained for a single page depending on which evaluation tool is being used.Taking into account that a fully automated Web accessibility evaluation is not feasible because of the nature of WCAG, this paper evaluates the WCAG automation coverage of some well known Web accessibility evaluation tools spotting their weaknesses and differences. We also provide a formalized specification for those checkpoints where these differences have been detected, thus challenging nowaday's tools for more automated coverage.     

Green synthesis of zinc oxide nanoparticles using <Emphasis Type="Italic">Citrus sinensis</Emphasis> extract

This work addresses a low cost, non-toxic green synthesis of zinc oxide nanoparticles prepared using different amounts of Citrus sinensis extract. The zinc oxide nanoparticles presented the Zn–O bond at 618 cm^?1, a crystalline growth in a purely hexagonal wurtzite crystal structure, and different size and shape homogeneity depending on the amount of extract used. The band gap of the ZnO was at around 2.91 eV for all samples. The photocatalytic degradation studies were carried out using methylene blue with the zinc oxide nanoparticles under UV light; where sample M2 presented a degradation of around 83% at 120 min. These results presented a better degradation rate than commercially available zinc oxide nanoparticles.