Spatial Quality Evaluation of Pedestrian Streets

This paper presents an assessment of the spatial quality of a pedestrian street located in downtown Bauru, S~o Paulo State, Brazil, from the application of some urban sustainability indicators. Multi-method was used to evaluate the thermal comfort quality of users, urban accessibility and preservation of architectural heritage. The results show that the sustainability indicators, apart from being effective tools in identifying problems, can assist local managers in decision making, planning and monitoring of pedestrian public space. These indicators contribute to a broad diagnosis of the pedestrian street and also the formulation of programs, projects and municipal policies, aimed at providing a better life quality for pedestrians.     

Highly linear micropower class AB current mirrors using Quasi-Floating Gate transistors

A design approach to achieve low-voltage micropower class AB CMOS cascode current mirrors is presented. Both class AB operation and dynamic cascode biasing are based on the use of Quasi-Floating Gate transistors. They allow high linearity for large signal currents and accurately set quiescent currents without requiring extra power consumption or supply voltage requirements. Measurement results show that dynamic cascode biasing allows a wider input range and a linearity improvement of more than 23 dB with respect to the use of conventional biasing. A THD value better than −35 dB is measured for input amplitudes up to 100 times the bias currents. Two class AB current mirror topologies are proposed, with slightly different ways to achieve class AB operation and dynamic biasing. The proposed current mirrors, fabricated in a 0.5 µm CMOS technology, are able to operate with a supply voltage of 1.2 V and a quiescent power consumption of only 36 µW, using a silicon area <0.025 mm².     

Synthetic Crystals of Silver with Carbon: 3D Epitaxy of Carbon Nanostructures in the Silver Lattice

Only minimum amounts of carbon can be incorporated into silver, gold, and copper in a thermodynamically stable form. Here, the structure of stable silver carbon alloys is described, which are produced by thermoelectrically charging molten silver with carbon ions. Transmission electron microscopy and Raman scattering are combined to establish that large amount of carbon is accommodated in the form of epitaxial graphene‐like sheets. The carbon bonds covalently to the silver matrix as predicted from density functional theory (DFT) calculations with bond energies in the range 1.1–2.2 eV per atom or vacancy. Graphitic‐like sheets embedded in the crystal lattice of silver form 3D epitaxial structures with the host metal with a strain of ≈13% compared to equilibrium graphene. The carbon nanostructures persist upon remelting and resolidification. A DFT‐based analysis of the phonon density of states confirms the presence of intense vibration modes related to the Ag? C bonds observed in the Raman spectra of the alloy. The solid silver–high carbon alloy, termed “Ag‐covetic,” displays room temperature electrical conductivity of 5.62 × 10⁷ S m^?1 even for carbon concentrations of up to ≈6 wt% (36 at%). This process of incorporation of carbon presents a new paradigm for electrocharging assisted bulk processing.     

An improved BEM model for the power curve prediction of stall‐regulated wind turbines

Blade element momentum (BEM) theory is the standard computational technique for the prediction of power curves of wind turbines; it is based on the two‐dimensional aerodynamic properties of aerofoil blade elements and some corrections accounting for three‐dimensional wing aerodynamics. Although most BEM models yield acceptable results for low‐wind and pitch‐controlled regimes where the local angles of attack are small, no generally accepted model exists up to date that consistently predicts the power curve in the stall regime for a variety of blade properties and operating conditions. In this article we present a modified BEM model which satisfactorily reproduces the power curves of four experimental wind turbines reported in the literature, using no free fit parameters. Since these four experimental cases comprehend a great variety of conditions (wind tunnel vs field experiments, different air densities) and blade parameters (no twist and no taper, no taper but twist, both twist and taper, different aerofoil families), it is believed that our model represents a useful working tool for the aerodynamic design of stall‐regulated wind turbines. Copyright © 2004 John Wiley & Sons, Ltd.     

Breeding strategies for improving the performance and fruit quality of the pepino (Solanum muricatum): A model for the enhancement of underutilized exotic fruits

The pepino (Solanum muricatum Aiton) is a neglected Andean crop that has elicited an increasing interest from exotic fruit markets. The pepino is highly diverse and, by using appropriate breeding strategies, it has been possible to develop new improved materials. Here we review more than a decade of efforts and advancements made in the genetic improvement of the pepino for several traits, with special emphasis on fruit quality. Different strategies, like the use of a wide diversity of genetic resources, exploitation of genotype × environment interaction, use of clonal hybrids, and introgression of genes from wild species, have facilitated significant developments in enhancing the commercial potential of the pepino, and have allowed the development of new cultivars and breeding materials adapted to new agroclimatic conditions. Agronomic performance of the pepino has been improved by the use of genetic parthenocarpy, selection for resistance to Tomato Mosaic Virus, and by developing hybrids, that manifested heterosis, but also did not have lower quality fruit. Breeding for quality has been focused mostly on the improvement of flavor (sweetness and aroma) and nutritional value (ascorbic acid content; AAC). Despite the limited intraspecific diversity available for sugar content, materials with high soluble solids content (SSC) have been selected. Strategies for further increases of SSC and titratable acidity have been based in the use of wild relatives. The study of variation within the cultigen was also helpful in the selection of hybrid genotypes with improved aroma profiles and high AAC values. As a result of the breeding efforts, several cultivars with improved agronomic performance and fruit quality have been produced. The use of biotechnological tools represents an opportunity to use the extensive genomic information compiled for related species, like tomato or potato, for the future improvement and enhancement of pepino quality. The results obtained in the pepino show that ample opportunities exist for improving the commercial potential of under-utilized fruits by means of breeding based on the exploitation of genetic diversity.     

Crystal Size,Morphology, and Growth Mechanism in Bio‐Inspired Apatite Nanocrystals

Bio‐inspired apatite nanoparticles precipitated in the presence of citrate ions at increasing maturation times are characterized in terms of structure, size, morphology, and composition through advanced X‐ray total scattering techniques. The origin of the platy crystal morphology, breaking the hexagonal symmetry, and the role of citrate ions is explored. By cross‐coupling the size and shape information of crystal domains with those obtained by atomic force microscopy on multidomain nanoparticles, a plausible mechanism underlying the amorphous‐to‐crystal transformation is reconstructed. In the present study, citrate plays the distinct roles of inducing the platy morphology of the amorphous precursor and controlling the thickness of the Ca‐deficient apatite nanocrystals. These findings can open new scenarios also in bone mineralization, where citrate might have a broader role to play than has been thought to date.     

Characterisation of Micrococcaceae isolated from different varieties of chorizo

A total of 426 strains of Micrococcaceae bacteria isolated from chorizo (a traditional Spanish fermented sausage) were identified. The chorizos were sampled from three regions of Castilla and León in Spain: Burgos, Segovia and Salamanca. Two factories were chosen in each region and the samples were taken at three stages of ripening. Staphylococcus xylosus was the most predominant species isolated (95%). Twelve strain types of S. xylosus were established according to their fermentation patterns, and two of them, S. xylosus type 2 and S. xylosus type 5, made up the majority of the strains of S. xylosus isolated (27 and 52%). Production of acetoin, nitrate reductase, urease activity, proteolytic and lipolytic activity were determined for all isolates. The percentage of strains of S. xylosus producing acetoin depends on the manufacturing location. In general, the proteolytic and lipolytic activities of the S. xylosus isolated from chorizo from Castilla and León were low and moderate; 97% of the strains showed nitrate reductase and urease activity. According to our results and to previous investigations, it seems that S. xylosus type 5, showing nitrate reductase and urease activity, low-moderate proteolytic and lipolytic activities and not producing acetoin would be suitable as a starter culture. Of the strains isolated in this study, 38% comply with these requirements.     

Development of a valved linear compressor for a satellite borne J-T cryocooler

The provision of temperatures below 12 K is essential for sub-mm and FIR observations from satellite instruments. Historically this has been achieved with stored cryogens, however mechanical coolers could potentially provide higher reliability and flexibility. These cryocoolers typically incorporate a regenerative cold-finger, such as a pulse-tube, however this can be replaced by a recuperative Joule-Thompson stage to obtain the lowest temperatures required. The major change to the compressor is the requirement for steady flow. This paper describes the development of such a compressor using reed valves, based on space-qualified hardware. Long life potential was demonstrated by measuring the motion of the valves during operation. A model was also developed and validated to optimize performance.