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6 figures, 3 tables., Perfluorinated sulfonic acid (PFSA) polymers such as Nafion® are widely used for both electrolyte membranes and ionomers in the catalytic layer of membrane-electrode assemblies (MEAs) because of their high protonic conductivity, σH, as well as chemical and thermal stability. The use of PFSA polymers with shorter side chains and lower equivalent weight (EW) than Nafion®, such as Aquivion® PFSA ionomers, is a valid approach to improve fuel cell performance and stability under drastic operative conditions such as those related to automotive applications. In this context, it is necessary to optimize the composition of the catalytic ink, according to the different ionomer characteristics. In this work, the influence of the ionomer amount in the catalytic layer was studied, considering the dispersing agent used to prepare the electrode (water or ethanol). Electrochemical studies were carried out in a single cell in the presence of H2-air, at intermediate temperatures (80–95 °C), low pressure, and reduced humidity ((50% RH). %). The best fuel cell performance was found for 26 wt.% Aquivion® at the electrodes using ethanol for the ink preparation, associated to a maximum catalyst utilization., This research was funded by the European Union’s Seventh Framework Programme (FP7/2007–2013) for Fuel Cell and Hydrogen Joint Technology Initiative under Grant no 303452 (IMPACT).

The membrane-electrodes assembly (MEA) is the core of the Polymer Electrolyte Fuel Cell (PEFC). It consists of a membrane, catalytic (CL) and gas diffusion layers (GDL). In order to manufacture MEAs with suitable performance, a hot-pressing procedure is generally used. The relevant parameters are the temperature, pressure and time of hot-pressing. Such variables need to be adjusted as a function of the type of ionomer used in the catalytic layer and membrane. In this study, an evaluation of the temperature of hot-pressing was carried out and its influence on MEA electrochemical performance was assessed. In particular, preparation trials of MEAs were carried out with reinforced experimental membranes based on Aquivion® short-side-chain PFSA (by Solvay Specialty Polymers). The membranes were coupled to gas diffusion electrodes, and MEAs were manufactured using different temperatures for the hot-pressing procedure in order to evaluate their influence on the electrochemical performance of PEFCs, in the temperature range of 80–95 °C, with low relative humidity of the reactant gases. The electrochemical performance of the prepared MEAs was tested in a H2/Air 25 cm2 single cell in terms of polarization curves and accelerated stress test (AST).

The controlled dispersion of polymeric sulfonic acids on suitable heterogeneous supports paves the way to a new catalytic method for the oxidation of a variety of benzylic methylenes to the corresponding carbonyls by using hydrogen peroxide; narrowly dispersed silica nanoparticles covered by fluorinated sulfonic acids ionomers allow selective oxidation of toluene to benzaldehyde, minimizing undesired side reactions and formation of wastes.

Over the last three years, a growing amount of reports highlighted the exceptional catalytic performances of Aquivion PFSA in many challenging chemical reactions. To date, all these studies employed Aquivion PFSA in powder form and the impact of shaping Aquivion PFSA on its catalytic performances has never been reported, although this aspect is of prime importance for implementation on a larger scale. Often considered as a matter of practical interest in the current literature, the shaping of a catalyst is actually mandatory and is clearly a key research topic for catalyst design and chemical engineering. Here, we explored the effect of shaping Aquivion PFSA on (1) its catalytic performances (i.e. yield, reaction rate and space time yield), (2) its ease of recovery at the end of the reaction (i.e. filtration, recyclability) and (3) its deactivation rate. In particular, we found that shaping Aquivion PFSA into micropellets was a good compromise (between powder and macropellets) to maintain acceptable catalytic performances while considerably facilitating the recovery of Aquivion PFSA at the end of the reaction. Last but not least, by properly controlling the reaction conditions, it was possible to limit the deactivation of Aquivion PFSA shaped into micropellets, a recurrent problem in catalytic carbohydrate processing.

This study reports the sustainable production of butyl levulinate (BL) from furfuryl alcohol (FA), a highly abundant biomass derived platform obtained from C5 sugars in hemicellulose. FA upgrading is performed adopting a robust and easily recyclable commercial perfluorosulfonic acid resin, Aquivion® P87S, used as cylinder shaped pellets. This approach avoids the use of corrosive and harmful mineral acids allowing a simple separation of the catalyst from the reaction mixture, reducing the cost of equipment materials and disposal or neutralization issues, also resulting in reduced solvent dehydration. Moreover, FA alcoholysis to BL involves butanol as a sustainable reaction medium, also readily obtained from biomass. The catalyst remains stable up to 6 recycles. Furthermore, the absence of heavy by-products and the stability of the catalyst allowed us to perform successive additions of the substrate to the reaction medium to increase the BL concentrations up to 0.66 M (13 wt%).

5-Hydroxymethylfurfural (HMF) production from catalytic dehydration of fructose was studied over mesoporous silica heterogenized perfluorosulfonic acid resin (Aquivion@silica) catalyst. Amphiphilic Aquivion PFSA was used as both acidic and template agent for the sol–gel synthesis of amorphous mesoporous silica which was found very appropriate to effectively immobilize Aquivion resin by using an impregnation method. Various characterizations including elemental analysis, acid-base titration, XRD, FTIR, Raman, N2 adsorption–desorption, SEM and TEM revealed that Aquivion@silica catalyst presented large surface area, sufficient porosity and afforded highly accessible sulfonic acid groups. Efficient and productive HMF production from the dehydration of fructose was achieved in the polar dimethyl sulfoxide (DMSO) solvent at low temperature of 90 °C, i.e. 85% yield of HMF and 43 molHMF molH+ productivity of HMF. The influence of reaction time, reaction temperature, Aquivion loading, catalyst dosage and solvent on the dehydration process was systematically investigated. The catalyst could be regenerated through a simple ion-exchange method and a stable HMF yield was maintained after being used four times.

We describe the rational design of a new versatile family of bifunctional catalytic materials based on the combination of supported metal nanoparticles (Pd, Rh, Ru) and the superacid, perfluorinated Aquivion (R) PFSA polymer. The heterogeneous catalysts were tested in the multi-step valorisation of representative plant derivatives to high-added-value chemicals. Particularly, the conversion of (+)-citronellal to (-)-menthol and levulinic acid to -valerolactone was achieved in one pot and in one stage in the water phase and shows full selectivity at a high conversion level under mild reaction conditions. The results are discussed in terms of the catalyst micro-structure.

A new generation of high performing polymer electrolyte membranes with ultralow platinum group metal loading (in total 0.44 mgPGM cm− 2) has been developed and characterized. High performance was achieved for MEAs based on the short-side chain Aquivion membrane (E98-09S), stabilized Solvay ionomer (D98-06ASX), and optimized catalysts developed by CNR-ITAE (cathode 40% Pt on C and anode: Ir0.7Ru0.3OX). The high performance was verified on several scales ranging from small single cells (3–8 cm2) at CNR-ITAE and IRD to short three-cell stacks at ITM, the latter MEAs having an active area of 130 cm2. A 4000-h single cell steady-state test at 3 A cm− 2 shows that the degradation rate of the ultralow PGM MEAs is 8 μV/h. Minimal reversible degradation was recorded at 80°C although this is pronounced at low temperature (55°C). Current and thermal cycling proved to have limited impact on degradation.

This manuscript explores the catalytic activity, selectivity and stability of Aquivion ® PFSA PW98 in the oligomerization of glycerol. Aquivion ® PFSA PW98 is a solid superacid catalyst with a Hammett acidity function of −12. Furthermore, the perfluorinated structure allows this polymer to stand quite high operating temperature (up to 150–160 °C) without loss in mechanical and chemical integrity which is of huge interest for glycerol conversion. In this context, we discovered that Aquivion ® PFSA PW98 was nearly fully selective to oligoglycerols up to 80% conversion of glycerol. The oligomerization degree of oligoglycerol and the regioselectivity of the reaction (linear vs branched and cyclic isomers) were fully analyzed by means of GC and SEC chromatographies. In contrast to conventional solid acid catalysts, Aquivion ® PFSA PW98 was found highly robust in glycerol and was sucessfully recycled at least 10 times without apparent decrease in activity or selectivity. A comparison with Nafion NR 50 is also included to shed light on the potential of Aquivion ® PFSA PW98 for acid-catalyzed conversion of glycerol.

6 Figuras, 4 Tablas, The large-scale application of polymer electrolyte membrane fuel cells (PEMFCs) requires a reduction of the costs and an improvement in performance and stability. Particularly, the automotive market needs the PEMFC works under harsh conditions (high temperature, low relative humidity, etc.), maintaining a good performance level and low degradation. These operating conditions permit to mitigate the constraints concerning the thermal and water management allowing both a simplification and a volume reduction of the system inside the car with a strong impact on costs and reliability. However, PEMFCs require the development of the components such as catalysts, ionomers and membranes with a proper stability. In this work, PtCo/KB and Pt/KB electrocatalysts were investigated with the aim of verifying the performance and stability, coupling them with an innovative reinforced Aquivion® membrane. An optimization of the catalytic ink composition was carried out, according to the different ionomers characteristics to be used in the catalytic layer in order to reduce the degradation level. The stability is assessed by considering the variations of the performance and electrochemical parameters, such as electrochemical surface area (ECSA) and mass activity (jm), at the beginning and end of accelerated stress test procedures., The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) for Fuel Cell and Hydrogen Joint Technology Initiative under Grant no 303452 (IMPACT).

The catalytic conversion of biomass and its derivatives into valuable chemicals requires efficient, energy saving, and sustainable technologies. In this work, a variety of bifunctional catalysts are prepared combining immobilized metal nanoparticles and acid solid materials featuring Lewis or Brønsted acidity. The catalytic systems are tested in the reductive amination of bio-derived levulinates with primary amines, using hydrogen as clean reducing agent, to obtain N-substituted-5-methyl-2-pyrrolidones, which are proposed as substitutes for the widely used, REACH-restricted solvent N-methyl-2-pyrrolidone. The overall process is studied in depth to identify the best combination of metal and acid functionalities to be used in one-pot and one stage. Pt immobilized onto the Brønsted solid acid Aquivion is shown to be the most efficient catalyst, with a productivity of N-heptyl-5-methyl-2-pyrrolidone of 7.9 mmolgcat-1 h-1 reached at full conversion and 98.6% selectivity, under 120 °C, 4 bar H2 pressure and solvent-free conditions.

Endothelial cells are constantly exposed to blood flow and the resulting frictional force, the wall shear stress, varies in magnitude and direction with time, depending on vasculature geometry. Previous studies have shown that the structure and function of endothelial cells, and ultimately of the vessel wall, are deeply affected by the nature of wall shear stress waveforms. To investigate the in vitro effects of these stimuli, we developed a compact, programmable, real-time operated system based on cone-and-plate geometry, that can be used within a standard cell incubator. To verify the capability to replicate realistic shear stress waveforms, we calculated both analytically and numerically to what extent the system is able to correctly deliver the stimuli defined by the user at plate level. Our results indicate that for radii greater than 25 mm, the shear stress is almost uniform and directly proportional to cone rotation velocity. We further established that using a threshold of 10 Hz of wall shear stress waveform frequency components, oscillating flow conditions can be reproduced on cell monolayer surface. Finally, we verified the capability of the system to perform long-term flow exposure experiments ensuring sterility and cell culture viability on human umbilical vein endothelial cells exposed to unidirectional and oscillating shear stress. In conclusion, the system we developed is a highly dynamic, easy to handle, and able to generate pulsatile and unsteady oscillating wall shear stress waveforms. This system can be used to investigate the effects of realistic stimulations on endothelial cells, similar to those exerted in vivo by blood flow.

A simple and broadly applicable preparation procedure to obtain silica-supported transition metal (namely Cr, Co and Mn)-based radical scavengers, containing sulfonic acid functionalities, is reported. These systems are widely characterised in terms of structure, bulk and surface composition and morphology by X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF), X-Ray Photoelectron Spectroscopy (XPS) and Transmission Electron Microscopy (TEM). The scavenger material is loaded in ePTFE reinforced membranes prepared from Aquivion ® perfluorosulfonic acid (PFSA) dispersions. All these composite membranes show longer lifetime in Accelerated Stress Tests (AST) and reduced fluoride release in Fenton's tests than the scavenger-free membranes without any loss in electrochemical performance. The Cr-scavenger-based polymer electrolyte shows a three-time larger stability than the pristine membrane.

A new protocol for the diasteroselective synthesis of pyrrolidin-2-ones 4–14 is presented. Aquivion PFSA effectively catalyzed the diasteroselective nitro-mannich/lactamization cascade reaction between the imine formed from aldehydes 1a–g and amines 2a–b with methyl 3-nitropropanoate 3. The use of flow conditions allow a very efficient waste minimization confirmed by representative green metrics calculations.

Here, we investigated that the mechanocatalytic depolymerization of cellulose in the presence of Aquivion, a sulfonated perfluorinated ionomer. Under optimized conditions, yields of water soluble sugars of 90-97% were obtained using Aquivion PW98 and PW66, respectively, as a solid acid catalyst. The detailed characterization of the water soluble fraction revealed (i) the selective formation of oligosaccharides with a DP up to 11 and (ii) that depolymerization and reversion reactions concomitantly occurred during the mechanocatalytic process, although the first largely predominated. More importantly, we discussed on the critical role of water contained in Aquivion and cellulose on the efficiency of the mechanocatalytic process.

The perfluorosulfonic acid (PFSA) Aquivion PW98 is an amphiphilic solid superacid which is shown to catalyze the conversion of cellulose into amphiphilic alkyl glycosides (AAGs) in 85 % yield (with 97 % selectivity). The process involves a mechanocatalytic depolymerization of cellulose followed by a direct glycosylation with n-dodecanol. In comparison to H2 SO4 and solid acid catalysts commonly employed in cellulose processing, Aquivion PFSA PW98 is not only recyclable but also exhibits superior catalytic performances in terms of yield, selectivity, and reactor productivity.

A facile synthesis, based on a wet impregnation technique and a thermal treatment, of a novel silica-supported cerium-oxide-based radical scavenger bearing sulfonic acid functionalities is presented. This material is loaded as a filler in ePTFE reinforced membranes (called R79-02S) prepared starting from Aquivion ® Perfluoro-Sulfonic Acid (PFSA) dispersions. The aim is to mitigate the peroxy radicals attack to the polymeric membrane under fuel cell operating conditions. These membranes show much longer (7 times more) life-time in Accelerated Stress Tests (AST) and reduced fluoride release (about one half) in Fenton's tests than the radical scavenger-free membrane without any loss in electrochemical performance. Scavenger-free Aquivion ® PFSA-based membrane durability is about 200 h in AST whereas the same membrane containing the newly developed radical scavenger exceeds 1400 h. These results confirm the stability of the modified membranes and the excellent activity of the composite scavenger in mitigating the polymer electrolyte degradation.

Recent interest in alternative energy technologies promoted the development of perfluorinated polymer membranes for fuel cells; the degradation mechanism occurring during operation and the polymer ageing that may lead to membrane failure are still a matter of investigation with the aim to identify proper testing protocols and analytical methods. This study illustrates some results obtained through micro Raman spectroscopy; this analytical technique showed itself to be a powerful tool in terms of spatial resolution and chemical data gathering. Detailed analytical and structural information along the cross sections of two membrane grades have been presented, shedding light on intrinsic structural modifications related to overall membrane performance. This study clearly shows an ununiformly distributed loss of sulfonic groups in two different Aquivion ® membrane grades, being the spectroscopic technique able to unveil very subtle effects due to equivalent weight and membrane thickness variations. The overall results support the mechanism previously proposed by other authors using different analytical techniques.

A robust method for coating polydimethylsiloxane (PDMS) allowing covalent binding of biomolecules is reported. The coating is based on adsorption of a copolymer, copoly(DMA-NAS-MAPS), bearing functional groups. The polymer is synthesized by free radical polymerization; it self-adsorbs onto the PDMS very rapidly, typically in 30 min, even without any PDMS surface pre-treatment. PDMS slides coated by copoly(DMA-NAS-MAPS) covalently bind amino-modified DNA fragments and have been tested in bacterial genotyping experiments. The usefulness of this functional coating on PDMS structures in lab-on-chip devices powered by microfluidics has been demonstrated. The copoly(DMA-NAS-MAPS) coated PDMS slides were used as flexible components of a microcell in semi-automated DNA microarray experiments for rapid food pathogen identification.

In the few last years, the need of reliable, fast and inexpensive methods for selective analysis of specific substances in complex mixtures has grown exponentially. In particular, the detection of biomolecules, such as oligonucleotides, proteins, peptides and carbohydrates is of outstanding importance in gene expression, drug design and medicine studies. To these purposes, molecular recognition on microarray-configured devices is one of the most promising tools. This technology uses a number of different substrates such as glass, silicon, alumina or gold-coated slides. The use of polymers is a very effective way to tailor surface properties introducing functional groups able to bind biomolecules and prevent denaturation and non-specific binding. Furthermore, advanced polymers, thanks to their particular physico-chemical properties, can be used to improve selectivity and sensitivity during assays. This review will provide very recent examples of polymer-mediated molecular recognition between guest molecules in solution and host molecules located at the solid phase.

Carboxy-terminated polyvinylpyrrolidin-2-one (PVP) has been used as a new water-soluble and biocompatible polymeric support for a series of ferrocene labeled amino acid and peptide nucleic acid (PNA) monomer derivatives 4 – 7 . The organometallic polymer-conjugates thus obtained are new and potentially useful as water-soluble electrochemically active probes for biomolecules. In view of such application, their electrochemical activity has been evaluated and has proved very high notwithstanding the complexity and bulkiness of the molecule, affording detection limits down to 10 −8 M in the aqueous medium.

Novel l-vinylpyrrolidin-2-one (VP) derivatives, namely 3,3-di(ethoxycarbonyl)-1-vinylpyr rolidin-2-one (DEVP) and 3-(ethoxycarbonyl)-l-vinylpyrrolidin-2-one (EVP), were obtained through a two-step synthetic pathway involving the abstraction of a hydrogen atom a to the lactam C=0, followed by condensation with ethyl chloroformate. By properly selecting the reaction conditions, DEVP could be obtained in high yields, through a straightforward purification procedure. Both DEVP and EVP were converted to sodium 1-vinylpyrrolidin-2-one-3-carboxylate (VP-COONa) by saponification of the ester group, followed by decarboxylation reaction in the case of DEVP. All monomers were homo- and copolymerized with VP by radical polymerization, the structure of the polymer obtained was determined by means of 1 H and 13 C NMR spectroscopy, and molecular weights were analyzed by means of size exclusion chromatography. The resultant DEVP- and EVP-based polymers also underwent hydrolysis with alkali solutions, followed by decarboxylation reaction in the case of DEVP units, which led in all cases to one carboxylate function linked to the lactam ring. The reactivity ratios for the copolymerization of DEVP with VP were determined in methanol solution according to the Kelen-Tudos procedure, through polymerization experiments performed at different feed, in which compositional drifts were followed by monitoring monomer conversions by means of 1 H NMR spectroscopy. The values of the reactivity ratios obtained were r DEVP = 0.63 and rvp = 0.33. The validity of these parameters was checked by means of the classical Skeist equation.

Thanks to their robustness, reliability and ease of use, step motor drives are widely used in several fields, mainly for small size automation. Step motor drives have also some well known bad running conditions related to their oscillatory behaviour and synchronism loss. In order to properly design the application, those conditions must be accurately taken into account setting-up proper mathematical models. In particular in this paper we refer to a simplified electro-mechanical model where the most of the parameters can be drawn from datasheets, while the others, as the equivalent damping factor, need experimental investigation. This paper deals with preliminary experimental activities performed on small size step motor drives for both testing the suitability of a test bench designed and developed in previous works, and outlining some remarks on the behaviour of the tested motors.

Multilayer actuators (MLA) are among the piezoelectric devices best suited to be introduced into fast and high-precision mechanical systems, because of their relatively large strokes and short actuation time. Several analytical models of their dynamic behaviour were developed during the last decades but none considered the real structure of the multilayer actuator. In this paper a more detailed model of a generic mechanical system driven by a piezoelectric multilayer actuator is presented. A complete description of such model is given and a comparison to existing modelling techniques is made. The behaviour of some commercially available actuators is analysed and results are discussed.

A new Aquivion™ E79-03S short-side chain perfluorosulfonic membrane with a thickness of 30 μm (dry form) and an equivalent weight (EW) of 790 g/equiv recently developed by Solvay-Solexis for high-temperature operation was tested in a pressurised (3 bar abs.) polymer electrolyte membrane (PEM) single cell at a temperature of 130 °C. For comparison, a standard Nafion™ membrane (EW 1100 g/equiv) of similar thickness (50 μm) was investigated under similar operating conditions. Both membranes were tested for high temperature operation in conjunction with an in-house prepared carbon supported Pt electrocatalyst. The electrocatalyst consisted of nanosized Pt particles (particle size ∼2 nm) dispersed on a high surface area carbon black. The electrochemical tests showed better performance for the Aquivion™ membrane as compared to Nafion™ with promising properties for high temperature PEM fuel cell applications. Beside the higher open circuit voltage and lower ohmic constraints, a higher electrocatalytic activity was observed at high temperature for the electrocatalyst-Aquivion™ ionomer interface indicating a better catalyst utilization.

Electro-hydraulic elevators are widely used systems, especially in low level buildings, due to their very good ratio between power generation and dynamic response. Generally, the goal of an elevator system is just to reach the floor with a precision enough to be comfortable for the passengers, without the need to follow a specific law of motion; hence an open-loop control system could be enough. Otherwise such a kind of solution reduces the number of components, bringing down the costs of production. On the other hand a complete knowledge of the mechanical system’s behaviour is required. In this work we deal with the analysis of the behaviour of a commercial hydraulic elevator driven by an open loop control that monitors the downstream pressure of the proportional valve supplying the cylinder. At the end of the paper, a closed loop solution based on the pressure measurement and on the motion time is proposed.Copyright © 2009 by ASME

In the hit to lead process, a drug candidate is selected from a set of potential leads by screening its binding with potential targets. This review focuses on the lead identification assays that employ a bio-chemical or bio-physical test to detect molecular recognition events between proteins and small molecules in a parallel format. These tests require either the lead or the target immobilization followed by incubation with the set of potential interaction partners and detection of a signal related to the target-ligand binding. In the first part of the review the different detection strategies amenable for drug screening are discussed. In the second part, a review of immobilization approaches for leads or targets, allowing the parallel screening of arrays of molecules, is presented.