Microstructure, mechanical properties and chemical degradation of brazed AISI 316 stainless steel/alumina systems

The main aims of the present study are simultaneously to relate the brazing parameters with: (i) the correspondent interfacial microstructure, (ii) the resultant mechanical properties and (iii) the electrochemical degradation behaviour of AISI 316 stainless steel/alumina brazed joints. Filler metals on such as Ag–26.5Cu–3Ti and Ag–34.5Cu–1.5Ti were used to produce the joints. Three different brazing temperatures (850, 900 and 950 °C), keeping a constant holding time of 20 min, were tested. The objective was to understand the influence of the brazing temperature on the final microstructure and properties of the joints. The mechanical properties of the metal/ceramic (M/C) joints were assessed from bond strength tests carried out using a shear solicitation loading scheme. The fracture surfaces were studied both morphologically and structurally using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction analysis (XRD). The degradation behaviour of the M/C joints was assessed by means of electrochemical techniques. It was found that using a Ag–26.5Cu–3Ti brazing alloy and a brazing temperature of 850 °C, produces the best results in terms of bond strength, 234 ± 18 MPa. The mechanical properties obtained could be explained on the basis of the different compounds identified on the fracture surfaces by XRD. On the other hand, the use of the Ag–34.5Cu–1.5Ti brazing alloy and a brazing temperature of 850 °C produces the best results in terms of corrosion rates (lower corrosion current density), 0.76 ± 0.21 μA cm−2. Nevertheless, the joints produced at 850 °C using a Ag–26.5Cu–3Ti brazing alloy present the best compromise between mechanical properties and degradation behaviour, 234 ± 18 MPa and 1.26 ± 0.58 μA cm−2, respectively. The role of Ti diffusion is fundamental in terms of the final value achieved for the M/C bond strength. On the contrary, the Ag and Cu distribution along the brazed interface seem to play the most relevant role in the metal/ceramic joints electrochemical performance.

Choreographic approaches to music composition for a new musical interface : the eMic

Gesture in performance is widely acknowledged in the literature as an important element in making a performance expressive and meaningful. The body has been shown to play an important role in the production and perception of vocal performance in particular. This paper is interested in the role of gesture in creative works that seek to extend vocal performance via technology. A creative work for vocal performer, laptop computer and a Human Computer Interface called the eMic (Extended Microphone Stand Interface controller) is presented as a case study, to explore the relationships between movement, voice production, and musical expression. The eMic is an interface for live vocal performance that allows the singers’ gestures and interactions with a sensor based microphone stand to be captured and mapped to musical parameters. The creative work discussed in this paper presents a new compositional approach for the eMic by working with movement as a starting point for the composition and thus using choreographed gesture as the basis for musical structures. By foregrounding the body and movement in the creative process, the aim is to create a more visually engaging performance where the performer is able to more effectively use the body to express their musical objectives.

Phase-Field Simulation of Fusion Interface Events during Solidification of Dissimilar Welds: Effect of Composition Inhomogeneity

We investigate the events near the fusion interfaces of dissimilar welds using a phase-field model developed for single-phase solidification of binary alloys. The parameters used here correspond to the dissimilar welding of a Ni/Cu couple. The events at the Ni and the Cu interface are very different, which illustrate the importance of the phase diagram through the slope of the liquidus curves. In the Ni side, where the liquidus temperature decreases with increasing alloying, solutal melting of the base metal takes place; the resolidification, with continuously increasing solid composition, is very sluggish until the interface encounters a homogeneous melt composition. The growth difficulty of the base metal increases with increasing initial melt composition, which is equivalent to a steeper slope of the liquidus curve. In the Cu side, the initial conditions result in a deeply undercooled melt and contributions from both constrained and unconstrained modes of growth are observed. The simulations bring out the possibility of nucleation of a concentrated solid phase from the melt, and a secondary melting of the substrate due to the associated recalescence event. The results for the Ni and Cu interfaces can be used to understand more complex dissimilar weld interfaces involving multiphase solidification.

A STUDY OF THE COMPOSITION DISTRIBUTION AT THE TI/AL2O3 INTERFACE USING THE MCS(+)-SIMS TECHNIQUE

In this article, the MCs(+)-SIMS technique has been used to characterize Ti/Al2O3 metal/insulator interfaces. Our experiment shows that by detecting MCs(+) secondary ions, the matrix and interface effects are reduced, and good depth profiles have been obtained. The experimental result also shows that with the increase of the annealing temperature (RT, 300 degrees C, 600 degrees C, 850 degrees C), the interface gets broadened gradually, indicating diffusion and reaction take place at the interface, and the interface reaction is enhanced with the increase in annealing temperature. When the temperature increases, the AlCs+ signal forms two plateaus in the Ti layer, indicating Al from the decomposition of Al2O3 diffuses into the Ti layer and exists as two new forms (phases). Also, with the increase of the annealing temperature, oxygen diffuses into the Ti layer gradually, and makes the O signal in the Ti layer increase significantly in the 850 degrees C annealed sample.

BitBox!: A case study interface for teaching real-time adaptive music composition for video games

Real-time adaptive music is now well-established as a popular medium, largely through its use in video game soundtracks. Commercial packages, such as fmod, make freely available the underlying technical methods for use in educational contexts, making adaptive music technologies accessible to students. Writing adaptive music, however, presents a significant learning challenge, not least because it requires a different mode of thought, and tutor and learner may have few mutual points of connection in discovering and understanding the musical drivers, relationships and structures in these works. This article discusses the creation of ‘BitBox!’, a gestural music interface designed to deconstruct and explain the component elements of adaptive composition through interactive play. The interface was displayed at the Dare Protoplay games exposition in Dundee in August 2014. The initial proof-of- concept study proved successful, suggesting possible refinements in design and a broader range of applications.

The lipid composition of a cell membrane modulates the interaction of an antiparasitic peptide at the air-water interface

The antiparasitic property of peptides is believed to be associated with their interactions with the protozoan membrane, which calls for research on the identification of membrane sites capable of peptide binding. In this study we investigated the interaction of a lipophilicglutathioine peptide known to be effective against the African Sleeping Sickness (ASS - African Trypanosomiasis) and cell membrane models represented by Langmuir monolayers. It is shown that even small amounts of the peptide affect the monolayers of some phospholipids and other lipids, which points to a significant interaction. The latter did not depend on the electrical charge of the monolayer-forming molecules but the peptide action was particularly distinctive for cholesterol + sphingomyelin monolayers that roughly resemble rafts on a cell membrane. Using in situ polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS), we found that the orientation of the peptide is affected by the phospholipids and dioctadecyldimethylammonium bromide (DODAB), but not in monolayers comprising cholesterol + sphingomyelin. In this mixed monolayer resembling rafts, the peptide still interacts and has some induced order, probably because the peptide molecules are fitted together into a compact monolayer. Therefore, the lipid composition of the monolayer modulates the interaction with the lipophilic glutathioine peptide, and this may have important implications in understanding how the peptide acts on specific sites of the protozoan membrane. (C) 2011 Elsevier B.V. All rights reserved.

The lipid composition of a cell membrane modulates the interaction of an antiparasitic peptide at the air-water interface

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Nanoscale surface and interface engineering : why plasma-aided?

This contribution provides arguments why and in which cases low-temperature plasmas should be used for nanoscale surface and interface engineering and discusses several advantages offered by plasma-based processes and tools compared to neutral gas fabrication routes. Relevant processes involve nanotexturing (etching, sputtering, nanostructuring, pre-patterning, etc.) and composition/structure control at nanoscales (phases, layering, elemental presence, doping, functionalization, etc.) and complex combinations thereof. A case study in p-Si/n-Si solar cell junction exemplifies a successful use of inductively coupled plasma-assisted RF magnetron sputtering for nanoscale fabrication of a bi-layered stack of unconventionally doped highly-crystalline silicon nanofilms with engineered high-quality interfaces.

Refactoring Service Interface to Support Artefact-centric Service interaction

The growth of APIs and Web services on the Internet, especially through larger enterprise systems increasingly being leveraged for Cloud and software-as-a-service opportunities, poses challenges for improving the efficiency of integration with these services. Interfaces of enterprise systems are typically larger, more complex and overloaded, with single operations having multiple data entities and parameter sets, supporting varying requests, and reflecting versioning across different system releases, compared to fine-grained operations of contemporary interfaces. We propose a technique to support the refactoring of service interfaces by deriving business entities and their relationships. In this paper, we focus on the behavioural aspects of service interfaces, aiming to discover the sequential dependencies of operations (otherwise known as protocol extraction) based on the entities and relationships derived. Specifically, we propose heuristics according to these relationships, and in turn, deriving permissible orders in which operations are invoked. As a result of this, service operations can be refactored on business entity CRUD lines, with explicit behavioural protocols as part of an interface definition. This supports flexible service discovery, composition and integration. A prototypical implementation and analysis of existing Web services, including those of commercial logistic systems (Fedex), are used to validate the algorithms proposed through the paper.

VIP Barcoding: Composition vector-based software for rapid species identification based on DNA barcoding

Species identification based on short sequences of DNA markers, that is, DNA barcoding, has emerged as an integral part of modern taxonomy. However, software for the analysis of large and multilocus barcoding data sets is scarce. The Basic Local Alignment Search Tool (BLAST) is currently the fastest tool capable of handling large databases (e.g. >5000 sequences), but its accuracy is a concern and has been criticized for its local optimization. However, current more accurate software requires sequence alignment or complex calculations, which are time-consuming when dealing with large data sets during data preprocessing or during the search stage. Therefore, it is imperative to develop a practical program for both accurate and scalable species identification for DNA barcoding. In this context, we present VIP Barcoding: a user-friendly software in graphical user interface for rapid DNA barcoding. It adopts a hybrid, two-stage algorithm. First, an alignment-free composition vector (CV) method is utilized to reduce searching space by screening a reference database. The alignment-based K2P distance nearest-neighbour method is then employed to analyse the smaller data set generated in the first stage. In comparison with other software, we demonstrate that VIP Barcoding has (i) higher accuracy than Blastn and several alignment-free methods and (ii) higher scalability than alignment-based distance methods and character-based methods. These results suggest that this platform is able to deal with both large-scale and multilocus barcoding data with accuracy and can contribute to DNA barcoding for modern taxonomy. VIP Barcoding is free and available at http://msl.sls.cuhk.edu.hk/vipbarcoding/.

Phase field study of precipitate growth: Effect of misfit strain and interface curvature

We have used phase field simulations to study the effect of misfit and interfacial curvature on diffusion-controlled growth of an isolated precipitate in a supersaturated matrix. Treating our simulations as computer experiments, we compare our simulation results with those based on the Zener–Frank and Laraia–Johnson–Voorhees theories for the growth of non-misfitting and misfitting precipitates, respectively. The agreement between simulations and the Zener–Frank theory is very good in one-dimensional systems. In two-dimensional systems with interfacial curvature (with and without misfit), we find good agreement between theory and simulations, but only at large supersaturations, where we find that the Gibbs–Thomson effect is less completely realized. At small supersaturations, the convergence of instantaneous growth coefficient in simulations towards its theoretical value could not be tracked to completion, because the diffusional field reached the system boundary. Also at small supersaturations, the elevation in precipitate composition matches well with the theoretically predicted Gibbs–Thomson effect in both misfitting and non-misfitting systems.

The Influence of Bilayer Composition on the Gel to Liquid Crystalline Transition

We report molecular dynamics simulations of bilayers using a united atom model with explicit solvent molecules. The bilayer consists of the single tail cationic surfactant behenyl trimethyl ammonium chloride (BTMAC) with stearyl alcohol (SA) as the cosurfactant. We study the gel to liquid crystalline transitions in the bilayer by varying the amount of water at fixed BTMAC to SA ratio as well as by varying the BTMAC to SA ratio at fixed water content. The bilayer is found to exist in the tilted, Lβ′ phase at low temperatures, and for the compositions investigated in this study, the Lβ′ to Lα melting transition occurred in the temperature range 330−338 K. For the highest BTMAC to SA composition (2:3 molar ratio), a diffuse headgroup−water interface is observed at lower temperatures, and an increase in the d-spacing occurs prior to the melting transition. This pretransition swelling is accompanied by a sharpening in the water density variation across the headgroup region of the bilayer. Signatures of this swelling effect which can be observed in the alkane density distributions, area per headgroup, and membrane thickness are attributed to the hydrophobic effect. At a fixed bilayer composition, the transition temperature (>338 K) from the Lβ′ to Lα transition obtained for the high water content bilayer (80 wt %) is similar to that obtained with low water content (54.3 wt %), confirming that the melting transition at these water contents is dominated by chain melting.

Precipitate growth with composition-dependent diffusivity: Comparison between theory and phase field simulations

We consider the growth of an isolated precipitate when the matrix diffusivity depends on the composition. We have simulated precipitate growth using the Cahn-Hilliard model, and find good agreement between our results and those from a sharp interface theory for systems with and without a dilatational misfit. With misfit, we report (and rationalize) an interesting difference between systems with a constant diffusivity and those with a variable diffusivity in the matrix.

Urban ecosystem services at the plant-soil interface

Continuing urbanization is a crucial driver of land transformation, having widespread impacts on virtually all ecosystems. Terrestrial ecosystems, including disturbed ones, are dependent on soils, which provide a multitude of ecosystem services. As soils are always directly and/or indirectly impacted through land transformation, land cover change causes soil change. Knowledge of ecosystem properties and functions in soils is increasing in importance as humans continue to concentrate into already densely-populated areas. Urban soils often have hampered functioning due to various disturbances resulting from human activity. Innovative solutions are needed to bring the lacking ecosystem services and quality of life to these urban environments. For instance, the ecosystem services of the urban green infrastructure may be substantially improved through knowledge of their functional properties. In the research forming this thesis, the impacts of four plant species (Picea abies, Calluna vulgaris, Lotus corniculatus and Holcus lanatus) on belowground biota and regulatory ecosystem services were investigated in two different urban soil types. The retention of inorganic nitrogen and phosphorus in the plant-soil system, decomposition of plant litter, primary production, and the degradation of polycyclic aromatic hydrocarbons (PAHs) were examined in the field and under laboratory conditions. The main objective of the research was to determine whether the different plant species (representing traits with varying litter decomposability) will give rise to dissimilar urban belowground communities with differing ecological functions. Microbial activity as well as the abundance of nematodes and enchytraeid worm biomass was highest below the legume L. corniculatus. L. corniculatus and the grass H. lanatus, producing labile or intermediate quality litter, enhanced the proportion of bacteria in the soil rhizosphere, while the recalcitrant litter-producing shrub C. vulgaris and the conifer P. abies stimulated the growth of fungi. The loss of nitrogen from the plant-soil system was small for H. lanatus and the combination of C. vulgaris + P. abies, irrespective of their energy channel composition. These presumably nitrogen-conservative plant species effectively diminished the leaching losses from the plant-soil systems with all the plant traits present. The laboratory experiment revealed a difference in N allocation between the plant traits: C. vulgaris and P. abies sequestered significantly more N in aboveground shoots in comparison to L. corniculatus and H. Lanatus. Plant rhizosphere effects were less clear for phosphorus retention, litter decomposition and the degradation of PAH compounds. This may be due to the relatively short experimental durations, as the maturation of the plant-soil system is likely to take a considerably longer time. The empirical studies of this thesis demonstrated that the soil communities rapidly reflect changes in plant coverage, and this has consequences for the functionality of soils. The energy channel composition of soils can be manipulated through plants, which was also supported by the results of the separate meta-analysis conducted in this thesis. However, further research is needed to understand the linkages between the biological community properties and ecosystem services in strongly human-modified systems.

The influence of temperature gradient and lowering speed on the melt-solid interface shape of GaxIn1-xSb alloy crystals grown by vertical Bridgman technique

Radially homogeneous bulk alloys of GaxIn1-xSb in the range 0.7 < x < 0.8, have been grown by vertical Bridgman technique. The factors affecting the interface shape during the growth were optimised to achieve zero convexity. From a series of experiments, a critical ratio of the temperature gradient (G) of the furnace at the melting point of the melt composition to the ampoule lowering speed (v) was deduced for attaining the planarity of the melt-solid interface. The studies carried out on directional solidification of Ga0.77In0.23Sb mixed crystals employing planar melt-solid interface exhibited superior quality than those with nonplanar interfaces. The solutions to certain problems encountered during the synthesis and growth of the compound were discussed. (C) 1999 Elsevier Science B.V. All rights reserved.