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In this work, the chemical de-alloying behavior of Au30Cu38Ag7Pd5Si20(at.%) amorphous alloy which was rapidly solidified from the melt in the form of ribbons were investigated. First a comparison between samples de-alloyed in nitric acid with and without HF was conducted to achieve homogeneous de-alloying process. Then the morphology and structure of nanoporous gold (NPG) were adjusted by tuning the de-alloying parameters, such as HNO3 concentration, electrolyte temperature and de-alloying time. Finally the surface enhanced Raman scattering(SERS) capability of the as-prepared NPG was evaluated using 4,4′-bi-pyridine as probe molecule.

Measurement of thin film magnetostriction is a challenging task, as magnetostrictive material deformations in parts per million, in conjunction with materials at small dimensions, require high precision, often with dedicated set-ups, for reproducible results. We have developed a novel approach employing a commercial atomic force microscope (AFM) with attached electromagnets. Magnetostriction measurements are demonstrated on 50–500 nm thick Fe81Al19 films sputter deposited directly on high aspect ratio commercial AFM micro-cantilevers. A magnetostrictive deflection of the cantilever bimorph translates into a deflection force acting in a contact mode measurement, which is interpreted and recorded as a change in height. For determination of the magnetostriction coefficient λ s , we have developed a modified version of the equation for the magnetostrictive deflection of a cantilever bimorph by Guerrero and Wetherhold, taking into account long-range attractive forces acting during contact mode AFM measurements in air. The sub-atomic precision of the AFM, combined with the widespread availability of all components and the simple set-up, makes the measurement of magnetostriction on films of just a few tens of nanometers thickness easily accessible.

Bimetallic nanomaterials in the form of thin film constituted by magnetic and noble elements show promising properties in different application fields such as catalysts and magnetic driven applications. In order to tailor the chemical and physical properties of these alloys to meet the applications requirements, it is of great importance scientific interest to study the interplay between properties and morphology, surface properties, microstructure, spatial confinement and magnetic features. In this manuscript, FePd thin films are prepared by electrodeposition which is a versatile and widely used technique. Compositional, morphological, surface and magnetic properties are described as a function of deposition time (i.e., film thickness). Chemical etching in hydrochloric acid was used to enhance the surface roughness and help decoupling crystalline grains with direct consequences on to the magnetic properties. X-ray diffraction, SEM/AFM images, contact angle and magnetic measurements have been carried out with the aim of providing a comprehensive characterisation of the fundamental properties of these bimetallic thin films.

Sputtering and electrodeposition are among the most widespread techniques for metallic thin film deposition. Since these techniques operate under different principles, the resulting films typically show different microstructures even when the chemical composition is kept fixed. In this work, films of Fe70Pd30 were produced in a thickness range between 30 and 600 nm, using both electrodeposition and sputtering. The electrodeposited films were deposited under potentiostatic regime from an ammonia sulfosalicylic acid-based aqueous solution. Meanwhile, the sputtered films were deposited from a composite target in radio frequency regime. Both approaches were proven to yield high quality and homogenous films. However, their crystallographic structure was different. Although all films were polycrystalline and Fe and Pd formed a solid solution with a body-centered cubic structure, a palladium hydride phase was additionally detected in the electrodeposited films. The occurrence of this phase induced internal stress in the films, thereby influencing their magnetic properties. In particular, the thickest electrodeposited Fe70Pd30 films showed out-of-plane magnetic anisotropy, whereas the magnetization easy axis lied in the film plane for all the sputtered films. The domain pattern of the electrodeposited films was investigated by magnetic force microscopy. Finally, nanoindentation studies highlighted the high quality of both the sputtered and electrodeposited films, the former exhibiting higher reduced Young’s modulus and Berkovich hardness values., Graphical Abstract

Quality of life and well-being are hardly ever an issue when life itself is at stake. The advantages of high-quality walkable streets and public spaces are underestimated when larger problems need to be addressed first and seemingly more serious solutions need to be applied. Hence, a quantitative approach to evacuation route planning and design prevails over a qualitative one or at least a hybrid one. The scope of the ongoing study partially presented in this paper is to find methods for addressing the complicated present and the disastrous future at the same time. The one applied in the case study reported here&mdash, Susaki City in Kōchi Prefecture, Japan, which is preparing for the next Nankai earthquake and tsunami, expected sometime soon&mdash, was a cycle of active research and international workshops organized in cooperation with the local community and administration. The aim was to understand the challenges that concern the design of dual spaces that are suitable for both everyday life and emergency situations and are connected by walkable spaces. As a result, the paper offers insight into the limits of punctual treatments as well as the relativity of objective and subjective dimensions of urban walkability in the context of risk. Despite the complexity of the issue, a walkable built environment was revealed to be a countermeasure rather than a fad.

Three dimensional nanoporous gold, with an average ligament size of 50 nm, was fabricated by chemical de-alloying from a new Au based metallic glass precursor. The resultant nanoporous gold gives rise to superior surface enhanced Raman scattering (SERS) capability using 4,4′-bi-pyridine as probe molecules. The SERS intensity mapping images confirm the presence of hot spots. A low detection limit down to 10 − 14 M for bipyridine was achieved, which is attributed to the localized enhanced electromagnetic fields around nano-sized ligaments, the electromagnetic coupling between ligaments, and the trapped SERS sensitive atoms.

De-alloying, i.e. selective dissolution of alloys, is currently studied to produce nanoporous gold items suited for use in catalysis, electrochemical applications, sensors and actuators. Both crystalline and amorphous alloys can be selectively etched. In the former, less noble atoms are removed from surface terraces of grains layer by layer, while noble ones form mounds. These evolve by undercutting and electrolyte percolation to form a ligament network. The mechanism of ligament development by de-alloying amorphous alloys is unknown. Here we show that for de-alloying a Au-based glass, in this case Au40Cu28Ag7Pd5Si20, percolation of the electrolyte through cracks of the native surface oxide initiates the formation of protuberances which are soon undercut. An interlayer develops, where Au crystals germinate, grow to nanometer size by diffusion and impinge. This is how ligaments start to coarsen. The interlayer is found at all stages between coarsened ligaments and amorphous phase. The ligaments are defective polycrystals, as opposed to single crystals obtained from crystalline alloys.

FePd alloys in the thin film form represent a multipurpose and versatile material with relevant chemical and physical properties studied in different research fields. Moreover, the ability to manipulate and fine-tune the film surface with nanometric scale precision represents a degree of freedom useful to adapt these thin film properties to the demands of different desired applications. In this manuscript, Fe70Pd30 (at. %) thin films are prepared with a thickness of 50 and 200 nm by means of the widely used co-sputtering deposition technique. Subsequently, selective removal of the iron element from the alloy and the consequent surface diffusion of the palladium was induced by a dealloying treatment under free corrosion conditions in hydrochloric acid. The size and shape of the grains of the as-deposited thin films determine the dissolution rate of the iron element with a direct consequence not only on the surface morphology and the stoichiometry of the alloy but also on the wetting and magnetic properties of the sample. X-ray diffraction, Scanning Electron Microscopy (SEM) images, contact angle and magnetic measurements have been performed to provide a thorough characterisation of the fundamental properties of these nanostructured bimetallic thin films.

We are currently observing a renaissance of the use of gaming simulation in urban planning. However, it is very rare that a game is followed up by so-called ‘debriefing’ after an urban gaming simulation (UGS), i.e., the practical applications drawing directly from the design process.

The development of a new generation of ultra-sensitive sensors for analytical and bio-diagnostic devices requires a strong signal in front of very small quantity of analyte, often present in complex and interfering matrix. Taking advantage of peculiar plasmonic properties of nanoporous gold (NPG), a promising sensor for selective detection of Human Serum Albumin (HSA), a proof-of-concept bioanalyte, was prepared and tested in a conventional micro-Raman spectrometer using Surface Enhanced Raman Spectroscopy (SERS). NPG was synthesized by chemical de-alloying of an amorphous precursor, Au20Cu48Ag7Pd5Si20, starting from melt spun ribbons. A fully de-alloyed ribbon with ligaments of about 60 nm was obtained after 4 h of de-alloying at 70 °C and 10 M HNO3 + 0.5 M HF. This material is self-standing, mechanically resistant, and suitable for wide range of applications. At this stage, NPG is SERS-active toward several molecules, including pyridine, bi-pyridine, and rhodamine at very low concentration. In order to obtain the selective binding properties required to detect molecules in bio-diagnostic applications, immuno-functionalization of NPG was carried out by using an anti-HSA antibody (Ab-anti-HSA) covalently grafted on gold ligaments via the 4-aminothiophenol (4ATP) Raman probe, yielding the SERS-active nanohybrid NPG-4ATP-Ab. SERS signal recorded at increasing HSA concentrations was used for the acquisition of SERS maps and a chemometric regression model allowed to calibrate the sensor. In the best experimental conditions, we were able to get quantitative analysis of HSA at ultra-low concentrations (0.1 ng/l) with SERS. The methodology proposed in this paper has to be considered a major step toward a calibrated device for ultra-sensitive detection of biomolecules by SERS detection.

This chapter discusses two case studies, which are part of our initiative to promote gaming simulation in Romanian business and educational settings. Our goal was to adapt “City of Emotions,” an urban planning gaming simulation, to other intervention and learning contexts. The first case study analyzes an organizational change intervention, where “City of Emotions” was used with the whole management team of a public Romanian company, in order to develop shared leadership and to help them find common ground for business innovation. Our second case study highlights the benefits of using “City of Emotions” to teach students about participatory processes and about the benefits of learning through interaction, as well as reflection in and on action. Feedback from participants in both situations was positive, both with regard to their somewhat new experience with gaming simulation and with regard to their learning outcomes.

In this work, Pt nanoparticles were electrodeposited through cyclic voltammetry technique on three dimensional nanoporous gold prepared from Au-based metallic glass precursor by chemical de-alloying. The electro-catalytic properties of the as-prepared samples were tested through potential cycling towards methanol oxidation in alkaline solution. Current density plots vs scan numbers indicate that the electrodes are active for the electro-oxidation of methanol and the Pt nanoparticles electrodeposited on gold ligaments contribute to increasing catalytic properties. In particular, results indicate that nanoporous gold with 30 cycles of Pt electrodeposition exhibits competitive higher activity and longer durability towards methanol electro-oxidation.

The purpose of this study was to clarify the construction of a gaming simulation model based on information scenarios obtained from questionnaire surveys in L’Aquila. A second objective was to discover the kinds of quality of life (QOL) factors affected by disaster information mismatch (DIM) when using a gaming simulation model based on information scenarios. This study conducted an experiment on the variation of QOL factors by DIM using a questionnaire survey for seven students. It is clarified that, if DIM occurred, then the victim’s QOL decreased compared to the situation with no DIM in each disaster phase. The results of this study indicate that the construction of disaster information sharing systems based on residents’ needs should be harmonized with public specialized information.

The protection of larger built-up areas that constitute sections of actively functioning urban zones is a challenge, even under favourable political and economic conditions. The case of Krakow’s historical town centre, which is protected as a historical site by national law and it was placed on the UNESCO World Heritage Sites List in 1978, clearly demonstrates how difficult it is to reconcile the passive character of current conservation doctrines with the demands of the free market and growth-oriented economy, when developer pressure is not sufficiently balanced out by public opinion and urban activist movements, when planning tools are incomplete or insufficient, and the criteria according to which strategic decisions are made are of a quantitative rather than a qualitative character. Apart from commonly encountered problems that are associated with the gentrification of town centres or the negative impact of mass tourism, Krakow must also face a growing flood hazard that stems from its specific and unfavourable hydrological and hydrogeological conditions that are compounded by the uncontrolled and uncoordinated expansion of urbanised areas, the decay of the natural environment, and the consequences of climate change. This article presents the multi-aspect site-specific conditions of the historical centre of Krakow, as well as the analysis of its protection as a UNESCO World Heritage Site, in the context of flood protection, while taking into consideration the environmental, economic, and social dimension of heritage. The critical conclusions that are featured in the work indicate both areas of possible immediate remedial action and the potential directions that new integrated protection strategies would take.

An integrated power system of a PEM fuel cell and hydride tanks designed for stationary applications is described. The work was focused on different aspects related to the development of the metal hydride tank and to its integration with the fuel cell, using water as thermal fluid. A commercially available LaNi 4.8 Al 0.2 intermetallic compound was chosen as hydrogen storage material, having sorption characteristics adequate to the working conditions of the system (i.e. 60 °C and 1 atm). Tanks were constituted by stainless steel, together with copper fins for improving heat exchanges between the thermal fluid and the tank. The performances of the integrated system were tested in different working conditions, in order to evaluate its reliability and efficiency. The system can operate for about 6 h, at an average power of 0.76 kW and delivering a total energy of 4.8 kW h, consuming about 3120 Nl of H 2 .

We are living in an era of diversity. Globalization has made it easier for people to move not just across the border but rather across the world, thus there are many ongoing issues with social cohesion and immigrant integration in urban neighborhoods. Immigrant integration as suggested by the IOM (International organisation for Migration) is a two-way process, which includes both the immigrant and the host society. Research has pointed out that the promotion of diversity in local neighborhoods is one of the integral solutions for immigrant integration. However, past evidence suggests that Thai people have a terribly limited understanding of the notion of diversity, and many of them still have prejudice in regard to migrant workers. The objectives of this research are (1) To evaluate the residents’ perception of understanding and acceptance toward the concept of immigrant integration and neighborhood co-existing diversity (2) To find out the effect of a gaming simulation on the resident and the immigrant. We introduce the Diverse Arrival Game as a game to promote diversity and immigrant integration. We implemented the gaming simulation along with pre-test and post-test questionnaires in a diverse neighborhood in Chiang Mai. The results show that the game improved perceptions in both groups toward neighborhood diversity. The game has the ability to promote mutual understanding among the local stakeholders and prompt the acceptance of the diversity concept that stimulates a powerful dialogue and ultimately leads to a new local initiative for diverse neighborhood planning.

In the framework of the European project SSH2S, a solid-state hydrogen storage tank - fuel cell system was demonstrated as Auxiliary Power Unit (APU) for a light duty vehicle. In this work, we have assessed the environmental impacts and the costs of the system developed. Following an eco-design approach, we have identified the processes mostly contributing to them and we have suggested possible improvements. By performing a Life Cycle Assessment (LCA), we found that, when the electricity consumption for hydrogen gas compression is included into the analysis, a solid-state hydrogen storage tank has similar greenhouse gas emissions and primary energy demand than those of type III and IV tanks. However, the resources depletion is higher for the solid-state system, even though the inclusions of the end of life of the APU and the recycling of the materials may result in different conclusions. The costs of an APU equipped with a solid-state hydrogen storage tank are significantly higher, about 1.5–2 times the systems based on type III and IV tanks. However, mature technologies are compared with a prototype, which has much room for optimization. To improve both the environmental and economic performances of the APU, a reduction of structural materials for both the solid-state hydrogen tank and Balance of Plant is recommended.

A novel catalyst for water splitting has been prepared by cyclic voltammetry (CV) deposition of amorphous MoS2 on nanoporous gold (NPG) obtained by electrochemical de-alloying a metallic glass precursor, Au40Cu28Ag7Pd5Si20 (at.%). As a function of number of CV cycles, Au ligaments are progressively encapsulated by a thin layer of amorphous MoS2 catalyst for hydrogen evolution. NPG provides a good substrate for deposition having excellent properties of handability and mechanical resistance in addition to catalytic activity, high conductivity and high surface area. Low onset potential, low Tafel slope and interesting values of exchange current density were obtained in linear sweep voltammetry of deposited samples. The synergistic behaviour of the multi-component material provides a highly efficient catalyst for hydrogen making of these samples a good candidate in some instances comparable to the conventional Pt catalyst for hydrogen evolution in acidic environment.

In this study, chemical de-alloying method was used to prepare nanoporous gold (NPG) from the Au containing amorphous alloy, with chemical composition of Au20Cu48Ag7Pd5Si20. Gold nanostructures were electrodeposited on the nanoporous gold by adjusting the applied potentials and deposition times. Using Rhodamine 6G (R6G) as probe molecule, the surface enhanced Raman scattering (SERS) activity of various Au nanostructures on nanoporous gold were compared. The dendritic nanostructures electrodeposited for 3000 s on NPG exhibited strongest SERS effect and high reproducibility. Using this best SERS active substrate for melamine sensing, the detection limit of 10−7 M was achieved.

In this study, Au-based nanoglasses in the form of thin films deposited by magnetron sputtering are comparatively dealloyed. The films have either nanograined or nanocolumnar microstructure, depending on the working pressure of Ar in the sputtering chamber. Nanocolumnar thin films exhibit much higher dealloying rate reducing effectively the dealloying time with respect to nanograined and homogenous thin films. Electrocatalysis experiments indicate that the resulting nanoporous films are active for the methanol electrooxidation, with promising results in term of stability especially for the dealloyed nanocolumnar film.

This paper examines the effect of different corrosion patinas on the chemical composition of copper‑tin alloys detected by portable X-ray Fluorescence Spectroscopy (pXRF). Specimens of Cu88Sn12 alloy with a composition close to that of ancient Egyptian copper-based alloys were corroded in three different aqueous solutions containing aggressive anions that can be found in Egyptian soil, for a maximum time of three months. After each sample was extracted, the elemental composition was determined with pXRF and the surface morphology and cross-sections were observed by metallographic microscopy to measure the thickness of the corrosion patinas. The cross-section of selected samples was analysed with Scanning Electron Microscopy equipped with Energy Dispersive X-ray Spectrometer (SEM-EDS). During the corrosion evolution of the copper alloy in the corrosive solutions of chlorides, decuprification phenomena made XRF data less accurate due to the development and thickening of Sn compounds (oxides or chlorides). Another problem encountered in the detection of the chemical composition of the Cu88Sn12 alloy was the bronze disease that strongly increased the corrosion process leading to the formation of an outer layer of atacamite and paratacamite, reaching a thickness of 150 μm. Conversely, during the corrosion process of the samples immersed in a sulphate solution, no changes in the initial composition of the Cu88Sn12 alloy were observed. The attenuation effect of the Sn concentration, by the thickness of green/dark green patinas with a high chloride content was observed on two Egyptian toilet spoons from the Museo Egizio (Turin) using pXRF. Following comparison of the chemical compositions in different corrosion patinas, it emerged that the red and grey patinas did not suffer the attenuation effects and, at these points of analysis, a reliable chemical characterisation of the alloy was obtained.

Corrosion studies in an acidic environment have been performed for the good Au40Cu28Pd5Ag7Si20 glass former with emphasis on the selective dissolution (de-alloying) process. The final porous microstructures obtained from fully amorphous ribbons and ribbons containing crystals as well as composition inhomogeneity in their amorphous matrix. The results are compared by using the same etching conditions. As reference, ribbons containing different crystalline fractions produced by isothermal annealing at temperatures in the glass transition region and then de-alloyed. The results show that a different mechanism of de-alloying operates for amorphous and crystallized materials. The finer homogenous nanoporous structure occurs after de-alloying a fully crystallized ribbon.

Nanoporous gold has been produced by the electrochemical dealloying of a Au 40 Cu 28 Ag 7 Pd 5 Si 20 metallic glass. Suitable conditions of potential and temperature of dealloying have been established from polarization curves and dealloying has been conducted at the critical potential of 1.05 V in three different electrolytes: 1 M HNO 3 , 1 M HClO 4 and 1 M H 2 SO 4 . The resulting material after 6 h of dealloying was constituted by ligaments made of pure Au and pores. The morphology was determined by SEM: ligaments of about 100 nm was observed and their size appears slightly larger (130 nm) when HNO 3 is used. In the first stages of dealloying (30–300 s), nanopores and nanocrystals, randomly oriented, were found by HRTEM. From these observations a diffusivity value for crystal growth was estimated. A change in growth mechanism was suggested when impingement occurs for long dealloying times. It is suggested that the ligament and pore morphology can be tailored in order to obtain materials with different chemical and physical properties.

Cold rolling of Al87Ni7La6 amorphous ribbons was performed on ribbons embedded in pure Al foils and ribbons alone, in order to study their deformation under constraint. A change in behaviour was observed for the two series of samples due to a different load distribution, so that ribbons alone was deformed up to ɛ = 0.029 without formation of cracks while, for composite samples, small fragments were always formed. In ribbons rolled alone, along with a macroscopic strain, a plastic deformation was observed at a finer scale, in the cavities present on the ribbon surface. The locally induced strain was quantified by taking into account the size change of cavities in samples rolled to different extents. The formation of shear bands and fracture occurring during cold rolling was studied for composite samples: the shear offset, interband spacing and distribution of fracture angles were determined. A Zr55Al20Ni12Cu8Ti5 amorphous ribbon was rolled with Al foils and the toughness value was estimated from the shear band offsets finding good agreement with literature data. Therefore, the toughness was estimated also for the Al-based samples obtaining the value of Kc = 28 MPa m1/2.

Multicomponent layered systems with tailored magnetic properties were fabricated via current annealing from homogeneous Fe67Pd33 thin films, deposited via radio frequency sputtering on Si/SiO2 substrates from composite target. To promote spontaneous nano-structuring and phase separation, selected samples were subjected to current annealing in vacuum, with a controlled oxygen pressure, using various current densities for a fixed time and, as a consequence, different phases and microstructures were obtained. In particular, the formation of magnetite in different amount was observed beside other iron oxides and metallic phases. Microstructures and magnetic properties evolution as a function of annealing current were studied and interpreted with different techniques. Moreover, the temperature profile across the film thickness was modelled and its role in the selective oxidation of iron was analysed. Results show that is possible to topologically control the phases formation across the film thickness and simultaneously tailor the magnetic properties of the system.

The process of de-alloying, i.e. removal of a less noble metal from an alloy, is applied here by electrochemical means to a Au-based metallic glass, Au 40 Cu 28 Ag 7 Pd 5 Si 20 , as a function of potential, temperature, and time. Very fine crystals nucleate with random orientation at the solid–electrolyte interface forming ligaments. The resulting material is constituted by ligaments made of pure Au and pores of smaller size whose dimensions coarsen up as a function of time to slightly above two hundred and below one hundred nanometers, respectively. The microstructure is uniform on both surfaces and across the ribbon. The extent of de-alloying is measured by monitoring the heat of crystallisation of the remaining amorphous phase giving linear trend vs time suggesting the reactions occur on continuously renewed surfaces.

New multinary amorphous materials, based on gold, that can be produced in bulk form due to their high glass-forming tendency, were discovered recently. However little is known about their corrosion properties. In the present study, the characterization of Au 49 Cu 26 . 9 Ag 5.5 Pd 2.3 Si 16.3 amorphous ribbons produced by melt spinning is reported. Their corrosion properties were tested by incubating the samples in artificial sweat and by monitoring the changes in surface structure by SEM and XRD. Before incubation, the surface of the samples was amorphous and flat, characterized only by microfeatures due to the liquid contact with the wheel during quenching. After treatment with artificial sweat, the formation of nanosized crystallites of Au on the sample surface was observed. The surface chemical composition of both sides of the ribbon samples was investigated by XPS. Atomic concentration and chemical states of constituent elements before and after the incubation in artificial sweat were determined. The depth profiling of both sides ofthe samples was carried out by using Ar ion sputtering combined with cyclic XPS measurements. The segregation of Si on one side of the samples and the changes of chemical composition, caused by the treatment in artificial sweat, were revealed.

Metallic glasses exhibit particularly attractive mechanical properties, like high stresses to fracture and large elastic strain (up to 2%), but they show generally low plasticity. Aim of this work is to investigate the glass forming range in the Cu–Y system, in order to form the ductile CuY phase (CsCl structure) upon crystallization. Cu58Y42, Cu50Y50 and Cu33Y67 alloys have been prepared by rapid solidification and copper mould casting, obtaining ribbons and cylindrical shaped ingots, with diameter of 2 mm. Fully amorphous, partially amorphous and fully crystalline samples have been obtained for different compositions and quenching conditions. In some cases, the X-ray diffraction results, analysed using the Rietveld method, showed CuY nanocrystals embedded in an amorphous matrix. The microstructure was studied by transmission electron microscopy (TEM) and the presence of nanocrystals of the ductile phase CuY has been confirmed. Microhardness results showed a softening of the amorphous phase due to the presence of CuY nanocrystals and a hardening due to the Cu2Y phase.

In this work, electrochemical de-alloying of an amorphous alloy, Au 40 Cu 28 Ag 7 Pd 5 Si 20 , cast in ribbon form by melt spinning, has been performed, obtaining self standing nanoporous materials suitable for use as electrodes for electrocatalytic applications. The de-alloying encompasses removal of less noble elements and the crystallization of Au, resulting in interconnected ligaments whose size and morphology are described as a function of time. Depending on de-alloying time, the crystals may contain residual amounts of Cu, Ag and Pd, as shown by Auger Electron Spectroscopy (AES), Energy Dispersive Spectroscopy (EDS) and Cyclic Voltammetry (CV) in a basic solution. Current density peaks in the 0.16–0.28 V range (vs Ag/AgCl) indicate that the porous ribbons are active for the electro-oxidation of methanol. The partially de-alloyed samples, which still partially contain the amorphous phase because of the shorter etching times, have finer ligaments and display peaks at lower potential. However, the current density decreases rapidly during repeated potential scans. This is attributed to the obstruction of Au sites, mainly by the Cu oxides formed during the scans. The fully de-alloyed ribbons display current peaks at about 0.20 V and remain active for hundreds of scans at more than 60% of the initial current density. They can be fully re-activated to achieve the same performance levels after a brief immersion in nitric acid. The good activity is due to trapped Ag and Pd atoms in combination with ligament morphology.

The metal assisted etching mechanism for Si nanowire fabrication, triggered by doping type and level and coupled with choice of metal catalyst, is still very poorly understood. We explain the different etching rates and porosities of wires we observe based on extensive experimental data, using a new empirical model we have developed. We establish as a key parameter, the tunneling through the space charge region (SCR) which is the result of the reduction of the SCR width by level of the Si wafer doping in the presence of the opposite biases of the p- and n-type wafers. This improved understanding should permit the fabrication of high quality wires with predesigned structural characteristics, which hitherto has not been possible.

The point of departure for this article is that it is difficult to use defined and structured gaming simulations in introductory sessions for negotiations, organisation of teamwork or meetings (in urban planning, community planning, community visioning, etc.) which should stimulate for the active participation. In fact their use demands aids and materials which are not always available, especially in short periods of time.

In this paper, two alternative integrated power systems were considered: one based on photovoltaic and hydrogen technology (electrolyzer coupled with a fuel cell), the other based on photovoltaic and batteries. The two systems, designed for off-grid applications, were sized for a photovoltaic energy production in the area of Turin, Italy, to provide 3 kW maximum power, with an average daily consumption of 10.25 kWh. The systems were compared from a technical and economical point of view and a Life Cycle Assessment analysis (LCA) was performed, to identify the main contributors to the environmental impact of the systems. From a commercial point of view, fuel cell and the electrolyzer are niche products, so the hydrogen-based power system results to be more expensive with respect to Li-ion batteries. From the environmental point of view, however, LCA results show the lower burdens of the hydrogen technology.

Experimental determinations of the glass transition and related properties in alloys are reviewed. Several recent measurements of viscosity, specific volume and heat capacity in the undercooling regime have become possible after the discovery of bulk glass forming alloys. The data allow verification of models on the kinetics and thermodynamics of such melts. The notion of melt fragility, borrowed from the description of inorganic and molecular glasses, has become popular also for metallic alloys: the kinetic fragility is described by the viscous behavior of the liquid and the thermodynamic fragility by the entropy loss on undercooling. The experimental viscosity data for metallic glass formers presently available can be reasonably framed within the strong–fragile classification. On the other hand, there are major discrepancies for the thermodynamic fragility of metallic glass formers with respect to conventional ones. The reason for such disagreement is twofold: on the experimental ground there are difficulties in obtaining fully reliable thermodynamic data in sufficiently wide temperature ranges; on the conceptual side the definition of the configurational entropy of the liquid with a suitable reference state is controversial. Among fragility indexes, the reduced width of the transition range proves most useful. The trend of the glass transition as a function of composition is also discussed in relation to the progressive ordering of the liquid on undercooling.

Soft magnetic materials are currently used in a variety of applications in electrical machines, sensors and elements of devices. If prepared in thin film form, they can be applied to micro- and nano-patterned devices. However, with respect to ribbons and bulk materials, thin films of the same composition usually display worse soft magnetic properties, thus requiring suitable solutions to restore high permeability and low coercivity. Thermal treatments are often exploited to this purpose on materials whose microstructure is in a local energy minimum: by providing sufficient energy to the atoms by means of suitable thermal treatments, the microstructure can be significantly changed in favour of a configuration with a much lower energy. In their new state, the physical properties of these systems can be significantly improved.

Mechanical properties of Al87Ni7RE6 amorphous and devitrified alloys (RE = Ce, Nd, La) are reported in this work. The microhardness of samples annealed at different devitrification stages is determined and an improvement is observed for all compositions when Al nanocrystals are present in the amorphous matrix. A further increase is found after a second transformation due to precipitation of an unknown phase in Al87Ni7Nd6. The fracture surfaces resulting from tensile tests of amorphous samples are examined both with scanning electron microscopy and transmission electron microscopy, where shear bands, vein patterns and protrusion are seen. There is no sign of crystallisation in shear bands and in vein patterns although their shape suggests a rise in temperature during deformation. Also in cold rolled samples the crystallization is avoided during deformation.

Supersaturated Au80Fe20 and Au70Fe30 solid solutions have been obtained by melt spinning. Heat treatments of as-quenched ribbons in the temperature range between 320 and 550 °C induced the precipitation of a fcc Fe-rich phase. From structural and microstructural analysis of precipitates and residual matrix, a discontinuous (cellular) transformation mechanism has been observed. Calculated driving forces for nucleation of bcc and fcc phases suggest a critical role of defect concentration on observed phase transformations.

This paper describes the crystallisation of Al 87 Ni 7 La 6 and Al 87 Ni 7 Sm 6 metallic glasses. The substitution of Sm for La in the alloy causes a variation in the transformation mode evidenced by the number of differential scanning calorimeter (DSC) peaks: two for the La containing alloy at low heating rates, than three at high heating rates, and three for the one with Sm. The glass transition becomes manifest for each alloys at a typical heating rate below which it is overlapped by the first crystallisation event due to precipitation of fine Al crystals in both materials. The Kissinger plot for Al 87 Ni 7 La 6 is not strictly linear as a possible consequence of overlapping processes. The second and third transformations of both alloys produce a metastable intermediate and the equilibrium phases, respectively. The second crystallisation steps of Al 87 Ni 7 Sm 6 and Al 87 Ni 7 La 6 involve linear Kissinger plots. The crystallisation behaviour of the two alloys is compared with that of Al 87 Ni 7 Ce 6 and Al 87 Ni 7 Nd 6 which were earlier shown to present two and three transformations, respectively.

Cu80−xNixFe20 (x=0, 5 and 20) alloys have been rapidly solidified by planar flow casting. X-ray diffraction (XRD) analysis of as-quenched ribbons shows bcc-Fe precipitates embedded in an fcc phase (x=0), two co-existing fcc solid solutions (x=5) and a complete solid solution of the parent elements (x=20). Thermal treatments in the temperature range between 400 and 600 °C give precipitation and spinodal decomposition reactions. These phase transformations have been evidenced from a variation of lattice constants, from a broadening of diffraction peaks and from TEM observations. The role of Ni content on competition between precipitation and decomposition reactions during rapid solidification and annealing is discussed in terms of thermodynamic arguments. Recent CALPHAD assessment of thermodynamic properties for Cu–Fe–Ni system has been used for an estimation of composition and volume fraction of equilibrium phases.

Immiscible alloys have been rapidly solidified for the preparation of granular materials with giant magnetoresistance properties. Au-based (Au–Co and Au–Fe) and Cu-based (Cu–Co and Cu–Fe) systems have been investigated. Single supersaturated solid solution has been obtained for Au–Fe, whereas three FCC solid solutions with different Co content have been found for Au–Co. For Cu–Co and Cu–Fe a limit of solubility in Cu has been observed. Ni additions to Cu–Fe strongly enhance solid solubility. A thermodynamic analysis has been used to describe the competition between partition-less solidification and phase separation in undercooled liquid.

The formation of nanoporous metals by de-alloying is not fully disclosed especially in the case of complex alloys such as amorphous ones. Here a crystalline porous scaffold made of ligaments and pores must originate from a matrix of diverse structure. In this paper a contribution to the field is achieved by pointing out differences that have been noticed comparing ligaments in de-alloyed materials obtained from either amorphous or crystalline precursors. Two multicomponent Au-based alloys in the form of ribbons, an amorphous Au40Cu28Ag7Pd5Si20 and a polycrystalline Au31Cu41Zn12.8Mn15.2, have been chemically de-alloyed in same conditions. The resulting nanoporous materials have been characterized by microscopy and diffraction and the kinetics of the process have been determined. The morphology of ligaments is definitely diverse as well as the size of crystals. This is proven by the ratio, r, between the ligament size and the size of scattering domains obtained by Rietveld analysis: the ligaments formed from the amorphous precursor are constituted by several crystals (r∼5) whereas ligaments from crystalline alloys contain a single domain (r∼1). The results are discussed in terms of surface diffusion and mechanism of growth of ligaments.

Nanoporous gold (NPG) has been synthesized by electrochemical de-alloying a new precursor, amorphous Au30Cu38Ag7Pd5Si20 (at.%), starting from melt-spun ribbons. Ligaments ranging from 75 to 210 nm depending on the de-alloying time were obtained. Analytical and electrochemical evidence showed the ligaments contain residual Cu, Ag and Pd. Surface-enhanced Raman scattering from the NPG was investigated using pyridine and 4,4′-bi-pyridine as probe molecules. It was found that the activity is at maximum when the ribbon is fully de-alloyed although the ligaments then have a larger size. The enhancement is attributed to the small size of crystals in the ligaments, to their morphology and to trapped atoms.