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Abstract The production of electric energy from solar radiation is nowadays one of the most investigated and developed "carbon free" technology. A throughout investigation of the ceramics most commonly used as heat transfer fluids and/or heat storage materials for concentrating solar power systems (i.e. alkaline and heart alkaline nitrate/nitrite mixtures) is here reported. The study stems by the need to base materials selection on an accurate and critical knowledge of all their characteristics, including their thermophysical, environmental compatibility, and economic features. At this purpose, a rating criterion have been established, to readily show the advantages and disadvantages of each material, and to highlight which characteristics of the examined materials need to be further investigated and improved. Nitrate/nitrite mixtures have also been compared with other ceramics used for thermal storage, such as solid fillers, liquid metals, other salt mixtures, or phase change materials. [ABSTRACT FROM AUTHOR]

Structure stability and electrical conductivity of La 1-x Sr x Fe 0.8 Cu 0.2 O 3-δ with x = 0.2, 0.4 were investigated both in air and in hydrogen to explore their potential applications as symmetric electrodes for solid oxide fuel cells. La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3-δ (LSGM) electrolyte supported symmetric fuel cells were fabricated and tested in air/hydrogen ambient in 650–800 °C temperature range achieving a maximum power density of 162 mW cm −2 . To improve the cell performance, a composite electrode (70 wt% La 1-x Sr x Fe 0.8 Cu 0.2 O 3-δ −30 wt% Gd 0.2 Ce 0.8 O 3-δ ) was successfully evaluated both at the anode and the cathode sides decreasing the cell polarization resistance to 0.454 Ω cm 2 at 800 °C and reaching a single cell maximum power density of 294 mW cm −2 . [ABSTRACT FROM AUTHOR]

The employment of parabolic trough solar power plants (PT-CSP) for electrical power and process heat generation is one of the most promising technologies for carbon free energy production. The selection of thermal fluids, both for the heat transfer (heat transfer fluid, HTF) and the storage (heat storage material, HSM), is a crucial point for increasing CSP efficiency and cost effectiveness. In this paper two different PT-CSP configurations, both presenting a double tanks storage system, are compared. In particular, two different medium size (50 MWe) plant schemes, presenting two different working fluids as HTF, are described and analysed. In the first scheme a “binary” molten salt mixture, composed of sodium and potassium nitrate, is considered, while, in the second one, the employment, as HTF, of a “ternary” mixture, consisting of sodium potassium and lithium nitrates, is investigated. In both cases, the binary mixture is used for thermal storage (HSM). The first scheme represents the configuration developed by ENEA and already used for the Archimede plant in Priolo Gargallo (Sicily-Italy). The second one is an innovative proposal, which aims to improve CSP plants performances and to reduce operating costs. In particular, since the ternary mixture has a considerably lower freezing temperature than the binary one, this solution allows to keep the system at a lower temperature overnight, so reducing thermal energy losses. In first instance, it is necessary to characterize the binary and ternary mixtures respect to their thermo-physical features. The two CSP configurations are then sized and, by a techno/economic evaluation, compared with respect to the calculated unit cost of electricity production. [ABSTRACT FROM AUTHOR]

In this work we present a transparent conductive oxide (TCO)-free flexible perovskite planar heterojunction solar cell made with a semitransparent anode realized with a highly conductive poly (3,4-ethylenedioxythiophene):poly(styrenesulfonate) PEDOT:PSS (PH1000 by Clevios) modified with ethylene glycol layer, deposited via spray coating. We investigated several formulations of PEDOT:PSS modified by addition of solvents with high boiling point such as ethylene glycol (EG) and dimethyl sulfoxide (DMSO). Optimized samples show a 65% transmittance at 550 nm and a sheet resistance of 28 Ω/□. On these optimized electrodes we fabricated a TCO-free flexible device, the best of which exhibited a power conversion efficiency of 4.9% under 100 mW/cm 2 illumination at AM1.5G. The efficiency of the perovskite planar-heterojunction solar cell, with the modified PEDOT:PSS anode was comparable to the one realized on a PET–ITO anode. Moreover, in the bending test, ITO-free flexible solar cell manifested superior mechanical robustness, showing the high flexibility of the perovskite layer. [ABSTRACT FROM AUTHOR]

Bone tissue engineering applications demand for biomaterials offering a substrate for cell adhesion, migration, and proliferation, while inferring suitable mechanical properties to the construct. In the present study, polyurethane (PU) foams were synthesized to develop a graded porous material—characterized by a dense shell and a porous core—for the treatment of oro-maxillary bone defects. Foam was synthesized via a one-pot reaction starting from a polyisocyanate and a biocompatible polyester diol, using water as a foaming agent. Different foaming conditions were examined, with the aim of creating a dense/porous functional graded material that would perform at the same time as an osteoconductive scaffold for bone defect regeneration and as a membrane-barrier to gingival tissue ingrowth. The obtained PU was characterized in terms of morphological and mechanical properties. Biocompatibility assessment was performed in combination with bone-marrow-derived human mesenchymal stromal cells (hBMSCs). Our findings confirm that the material is potentially suitable for guided bone regeneration applications. [ABSTRACT FROM AUTHOR]

Thermochemical water splitting cycles, where the H 2 O molecule is converted into hydrogen and oxygen by using recyclable and in general inorganic compounds as intermediates, basically consist of two separate sections, where, respectively, hydrogen and oxygen are produced. The most investigated cycles are based on the employment of sulphur containing species; generally, they differs with respect to how hydrogen is produced, but, basically, the step for oxygen formation is invariably a thermo-catalytical solar powered SO 3 decomposition. Despite several important studies were dedicated to the development of a solar reactor for this task, the manageability of a solar receiver plant presenting a corrosive acid at high temperature is still a problematic issue. With the main target to reduce the materials cost of the necessary equipment, an intermediate metal oxide is employed; it is reacted with sulphuric acid or ammonium sulphate (according to the cycle considered) to produce the correspondent metal sulphate, which, in turn, is decomposed into sulphur dioxide and oxygen. The present article describes the experimental results obtained for each cycle step, two oxide/sulphate (iron (III) and Zn) systems are used and compared, and, all considered, the couple zinc oxide/sulphate appears to be the most feasible for the process, though, the use of iron (III) sulphate would allow to operate the process at a maximum temperature below 700 °C. A mass and thermal balances analysis for the proposed oxygen production steps were carried out, and results are compared with the reported values where sulphuric acid is directly decomposed, with a final discussion about advantages and drawbacks of both methods. [ABSTRACT FROM AUTHOR]

La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3− δ (LSGM) perovskite oxide was selected as electrolyte to fabricate reduced-temperature solid oxide fuel cells (SOFCs). Porous/dense ceramic bilayers were optimized by using different pore forming agents. Reduced temperature (700 °C) infiltration method was employed to obtain anodes with nano-sized metal oxidation catalysts. The type and amount of porogen necessary to get a proper anodic porosity were evaluated together with the amount of infiltrated Ni catalyst to obtain promising electrochemical results. [ABSTRACT FROM AUTHOR]

Abstract: This paper reports on the determination of elastic and hardness properties of Co–B composite nanoparticles (CNP). Co boride materials is usually known for their functional properties (hydrogen catalysis, magnetism, corrosion, biomedics), but nanoscale dimensions also bring significant mechanical properties. In situ compression tests of 70–150nm core–shell silica-coated Co2B CNP (Composite nanoparticles) were performed for the first time with a nanoindenter in the load range 30–300μN. The CNP modulus is comparable with the bulk material (E CNP =159–166GPa), but the hardness is as much as 5 times higher (∼4.5±1.0GPA). Both modulus and hardness (to a lesser extent) are found to increase with the applied pressure. The paper first addresses the limitations of ordinary contact analysis intended for single-phase NP, and then presents a hybrid Oliver–Pharr strategy suitable for CNP, where numerical modeling overcomes issues related to anisotropy and heterogenety of the composite nanostructure that hinder the direct application of basic contact models. An alternative regression-based approach for estimating modulus and hardness is also considered for comparison. The importance of the model selection for the contact area A for accurate modulus and hardness results is emphasized. Besides typical Hertzian, geometrical and cylindrical area models, a new one is formulated from a “rigid-sphere” approximation, which turned out to perform best and consistently in this study, on a par with the cylindrical model. Finally, evidence of the magnetic nature of CNP and, unexpectedly, reverse plasticity is provided. [ABSTRACT FROM AUTHOR]

Abstract: A nanocomposite re-cast Nafion hybrid membrane containing titanium oxide calcined at T =400°C as an inorganic filler was developed in order to work at medium temperature in polymer electrolyte fuel cells (PEFCs) maintaining a suitable membrane hydration under fuel cell operative critical conditions. Nanometre TiO2 powder was synthesized via a sol–gel procedure by a rapid hydrolysis of Ti(OiPr)4. The membrane was prepared by mixing a Nafion–dimethylacetammide (DMAc) dispersion with a 3wt% of TiO2 powder and casting the mixture by Doctor Blade technique. The resulting film was characterised in terms of water uptake and ion exchange capacity (IEC). The membrane was tested in a single cell from 80 to 130°C in humidified H2/air. The obtained results were compared with the commercial Nafion115 and a home-made recast Nafion membrane. Power density values of 0.514 and 0.256Wcm−2 at 0.56V were obtained at 110 and 130°C, respectively, for the composite Nafion–Titania membrane. Preliminary tests carried out using steam reforming (SR) synthetic fuel at about 110°C have highlighted the benefit of the inorganic filler introduction when PEFC operates at medium temperature and with processed hydrogen. [Copyright &y& Elsevier]

Abstract: The possibility of combining inorganic and organic components at the nanosize level in a single material by the sol–gel process has made possible the development of new multifunctional materials. However, the phase interaction between organic and inorganic moieties can be controlled only to a limited extent by using hydrolysis–condensation reactions of metal alkoxides. The preparation of nanostructured organic–inorganic (O/I) materials by assembling of nanobuilding blocks (nbb) allows controlling the extent of phase interaction, which in its turn governs the structure–properties relationships. A suitable method is the preparation of inorganic nanosized preformed objects exploiting the features and the reactivity of functional end-capping organic groups. We present here the synthesis of Si- and Zr-based nanobuilding blocks prepared by reacting diphenylsilanediol and Si and Zr precursors, with M-OR or M-Cl functions. The non-hydrolytic condensation between silanols and alkoxide or chloride groups has been exploited in order to obtain the Si- and Zr-based nbb. These nanosized objects have been further processed by dip coating for preparing films starting from suitable solutions. The structural characterisation of prepared nbb has been obtained using infrared and nuclear magnetic resonance techniques. [Copyright &y& Elsevier]

Abstract: TiO2 nanometric powders were prepared via a sol–gel procedure and calcined at various temperatures to obtain different surface and bulk properties. The calcined powders were used as fillers in composite Nafion membranes for application in high temperature direct methanol fuel cells (DMFCs). The powder physico-chemical properties were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and pH measurements. The observed characteristics were correlated to the DMFC electrochemical behaviour. Analysis of the high temperature conductivity and DMFC performance reveals a significant influence of the surface characteristics of the ceramic oxide, such as oxygen functional groups and surface area, on the membrane electrochemical behaviour. A maximum DMFC power density of 350mWcm-2 was achieved under oxygen feed at 145°C in a pressurized DMFC (2.5bar, anode and cathode) equipped with TiO2 nano-particles based composite membranes. [Copyright &y& Elsevier]

The ALTEA project investigates the risks of functional brain damage induced by particle radiation in space. A modular facility (the ALTEA facility) is being implemented and will be operated in the International Space Station (ISS) to record electrophysiological and behavioral descriptors of brain function and to monitor their time dynamics and correlation with particles and space environment. The focus of the program will be on abnormal visual perceptions (often reported as “light flashes” by astronauts) and the impact on retinal and brain visual structures of particle in microgravity conditions. The facility will be made available to the international scientific community for human neurophysiological, electrophysiological and psychophysics experiments, studies on particle fluxes, and dosimetry.A precursor of ALTEA (the `Alteino'' project) helps set the experimental baseline for the ALTEA experiments, while providing novel information on the radiation environment onboard the ISS and on the brain electrophysiology of the astronauts during orbital flights. Alteino was flown to the ISS on the Soyuz TM34 as part of mission Marco Polo. Controlled ground experiments using mice and accelerator beams complete the experimental strategy of ALTEA. We present here the status of progress of the ALTEA project and preliminary results of the Alteino study on brain dynamics, particle fluxes and abnormal visual perceptions. [Copyright &y& Elsevier]

The ALTEA project partecipates to the quest for increasing the safety of manned space flights. It addresses the problems related to possible functional damage to neural cells and circuits due to particle radiation in space environment. Spcifically it aims at studying the functionality of the astronauts'' Central Nervous Systems (CNS) during long space flights and relating it to the peculiar environments in space, with a particular focus on the particle flux impinging in the head. The project is a large international and multidisciplinary collaboration. Competences in particle physics, neurophysiology, psychophysiology, electronics, space environment, data analyses will work together to construct the fully integrated vision electrophysiology and particle analyser system which is the core device of the project: an helmet-shaped multy-sensor device that will measure concurrently the dynamics of the functional status of the visual system and passage of each particle through the brain within a pre-determined energy window. ALTEA is scheduled to fly in the International Space Station in late 2002. One part of the multy-sensor device, one of the advanced silicon telescopes, will be launched in the ISS in early 2002 and serve as test for the final device and as discriminating dosimeter for the particle fluences within the ISS. [Copyright &y& Elsevier]

NASICON (Na3Zr2Si2PO12) has been prepared by a sol-gel route. The progress of the reaction in the liquid has been monitored by means of 31P NMR spectroscopy. The dependence of phase formation and sintering behaviour of films and powders on sol-gel reactions and heat treatments was investigated. X-ray diffraction measurements showed the formation of monoclinic NASICON phase from 800 °C for powders and from 900 °C for films together with free ZrO2. An almost pure NASICON phase was observed in powders calcined at 1000 °C. Sintered pellets showed densities up to 98% of theoretical value. The microstructure of the samples was analysed by scanning electron microscopy. [ABSTRACT FROM AUTHOR]

• Low freezing mixture as heat transfer fluid and storage material for solar plants. • Thermo-physical and stability investigation of a low freezing molten salt mixture. • Solar parabolic plant sizing. • Active direct storage system with a low freezing molten salt mixture. • Techno-economic analysis according to the estimated electric energy cost per KWh. The selection of a proper heat transfer (HTF) and storage (HSM) material is a key parameter in the design of a CSP system, especially in the employment of parabolic trough concentrating solar power plants (CSP). The use of nitrates as HTF, alternatively to thermal oils, can increase the CSP efficiency and several mixtures have been proposed at this aim. The most employed molten nitrate salt is the so called "solar salt" that presents several advantages but also a relative high liquidus temperature point of 238 °C. The use, either as HTF or HSM, of a low melting mixtures is currently considered a promising alternative to decrease the investment cost and improve the manageability of CSP plants. In this work, a low melting fluid was selected, composed of calcium, sodium and potassium nitrate, and proposed to be used both as HTF and HSM in a direct and active storage system. The electric LCOEs was calculated for a medium size (50 MWe) plant located at the Priolo Gargallo site (Sicily-Italy). In order to evaluate the obtained outcome, the identical procedure was carried out considering the same size and location, and the "solar salt" and a thermal oil as heat transfer fluids, with the former as storage medium. The comparison between the results show that there is a clear, although limited, economic benefit in using the ternary mixture. [ABSTRACT FROM AUTHOR]

Nanocomposite ZrO2-added PEO-based solid polymer electrolytes and nanocomposite Ag-added LiFePO4 cathodes have been utilized to realize all solid state metallic lithium batteries. In this work the electrochemical properties of these materials will be illustrated and discussed. [Copyright &y& Elsevier]