Polyelectrolyte behaviour of acrylonitrile methallylsulphonate copolymers in dimethylformamide

The properties in organic solvent (DMF) of two ionic copolymers are investigated and compared to those of polyelectrolytes in aqueous solutions. First, the viscometric behaviour is disccussed: it is demonstrated that [η] varies linearly with $\text{C}{}^{\mathrm{<mtext>?1</mtext><mtext>2</mtext>}}{}_{\mathrm{T}}$, where C_T is the ionic concentration of the solution. At infinite salt concentration we obtain data in agreement with unperturbed dimensions. Using isoionic dilution, we deduce ø_p, the osmotic coefficient. From osmometry, the dependence of ø_p on the concentration is obtained and compared to the theoretical value. In the presence of neutral salt, the osmotic pressure is determined as a function of salt and polymer concentrations. The results are interpreted in terms of a Donnan equilibrium.     

A novel architecture of a tunable bandpass BAW-filter for a WCDMA transceiver

This paper presents an integrated tunable filter using Bulk Acoustic Wave (BAW) resonators, designed and fabricated in a 0.25 μm BiCMOS process. This filter is intended to be used in a zero-IF W-CDMA receiver between the LNA and the mixer. BAWs resonators turn out to be very attractive and competitive components thanks to their high Q-factor at high frequencies. Moreover, BAW technology, unlike Surface Acoustic Wave (SAW) technology, is compatible with Silicon process technology and allows a considerable reduction of the circuit area. However, because of its stacked structure and the thin thickness of materials to deposit, such devices are sensitive to process. They also suffer from temperature dispersions. The presented filter offers a reduced sensitivity to process and temperature variations thanks to its tunability. It allows correcting thermal and process dispersions on the piezoelectric layer of the BAW devices. The tuning is achieved through additional passive components (Q-enhanced inductance and varicaps). Simulations exhibit a tuning range of 1.4% for a 2.4 mA current consumption at 2 GHz. Good in-band linearity and noise performances have also been simulated. Stephane Razafimandimby was born in Lehon, France, in 1979. He received the engineering degree in electronics from the Institut Supérieur d'Electronique du Nord (ISEN), Lille, France, in 2003. Since 2003, he has been working toward the Ph.D. degree with STMicroelectronics, Crolles, France in collaboration with the Institut d'électronique, de Microélectronique et de Nanotechnologies (IEMN)/ISEN, Lille, France. His actual work and main research interests include RF integrated circuits and notably the feasability of integrating MEMS for mobile devices. Cyrille Tilhac was born in Tulle, France, in 1979. He received the master degree in radio-frequency and microwave communications from the Faculté des Sciences et Techniques de Limoges, France, in 2003. Since 2003, he has been working toward the Ph.D. degree with STMicroelectronics, Crolles, France in collaboration with the XLIM research laboratory, MINACOM department, Limoges, France. His actual work and main research interests include RF integrated circuits and particularly the integration of bulk acoustic wave resonators into RF devices. Andreas Kaiser (S'84, M'87) received the engineering diploma from the Institut Supérieur d'Electronique du Nord (ISEN), Lille, France, in 1984. In 1990 he received the PhD degree and in 1998 the HDR degree, both from the University of Lille. In 1990 he joined the Centre National de la Recherche Scientifique (CNRS) where he is responsible for the analog/RF IC design group at the Institut d'Electronique, de Microelectronique et de Nanotechnologies (IEMN) in Villeneuve-d'Ascq. He is also a Professor at ISEN. He published numerous papers on continuous and discrete time analog circuits, data-converters, RF-MEMS and analogue design automation. Prof. Kaiser served as Programme Chairman of the European Solid State Circuits Conference in 1995 and 2005 respectively. Andreia Cathelin was born in Bucarest, Romania. She started her electronic studies at the Polytechnic Institute of Bucarest, Romania and graduated from the Institut Supérieur d'Electronique du Nord (ISEN), Lille, France in 1994. From 1994 till 1998, she prepared a Ph. D. thesis with IEMN/ISEN, Lille, France and MS2 Company, Roubaix, France on a fully-integrated BiCMOS low power—low voltage FM/RDS receiver. From 1997 till 1998, she was with Info Technologies, Gradignan, France, working on analog and RF communications design. Since 1998, she is with STMicroelectronics, Crolles, France, in the Central R&D Division. Her major fields of interest are analog filtering, RF systems for mobile communication solutions, as well as MEMS devices co-integration. Didier Belot received the “D.U.T Electronique” degree from the “Institut Universitaire de Technologie” of Grenoble, Grenoble France in 1982, and the M.S. degree from the “Ecole Nationale Superieure d'Electronique et de Radioelectricite de Grenoble”, Grenoble France in 1991. In 1983, he joined the Bipolar Device Characterization and Modelization group, Thomson Semiconductor. In 1986, he joined Thomson “Etude et Fabrication de Circuits Integres Speciaux”, where he was involved with digital CMOS design. In 1988, he was involved with the design of high speed ECL/CML data communication ICs at STMicroelectronics. In 1996 he moves to the Radio Frequency design. Presently he manages a design group involved with the development of circuits for Mobile Phones and Local Network standards in Central Research and Development, STMicroelectronics, Crolles, France.     

An Algorithm to compute damage from load in composites

We present a new method to model fracture of concrete based on energy minimisation. The concrete is considered on the mesoscale as composite consisting of cement paste, aggregates and micro pores. In this first step, the alkali-silica reaction is taken into account through damage mechanics though the process is more complex involving thermo-hygro-chemo-mechanical reaction. We use a non-local damage model that ensures the well-posedness of the boundary value problem (BVP). In contrast to existing methods, the interactions between degrees of freedom evolve with the damage evolutions. Numerical results are compared to analytical and experimental results and show good agreement.     

Highly Dispersed Palladium–Polypyrrole Nanocomposites: In‐Water Synthesis and Application for Catalytic Arylation of Heteroaromatics by Direct C–H Bond Activation

Pd@PPy hybrid catalytic materials are synthesized in water via redox polymerization reaction of pyrrole with [Pd(NH₃)₄Cl₂]. The nanocomposites formed are composed of highly dispersed palladium particles which are either zerovalent or easily reducible, and are embedded in spherical polypyrrole globules. A unique combination of high palladium dispersion (NP size: 2.4 nm) and elevated palladium content (35 wt%) is obtained. The components of these novel nanocomposites are characterized by means of FTIR, XPS, XRD, SEM, and TEM microscopy techniques. The process of formation in solution is also monitored using UV‐visible and DLS techniques. The application of these novel hybrid nanomaterials in the palladium‐catalyzed direct arylation of heteroaromatics is reported. High efficiency in C–C bond formation is obtained using these materials. Furans and thiophenes are arylated by using bromoarenes. Pd@PPy nanocomposites can efficiently couple n‐butyl furan and n‐butyl thiophene with bromobenzene and bromoquinoline, as well as with activated or deactivated electron‐poor and electron‐rich functionalized bromoarenes. Thus, a clean reaction process is developed that combines the absence of organic ligand in catalytic reactions and easy recovery of Pd@PPy nanocomposite via simple filtration. Preliminary kinetic and post‐catalysis studies suggest a molecular or colloidal soluble active species. These very active species are efficiently delivered by the nanocomposites and susceptible to a surprisingly uniform back redeposition within the polypyrrole support.     

The Use of Nanoparticles to Deliver Nitric Oxide to Hepatic Stellate Cells for Treating Liver Fibrosis and Portal Hypertension

Polymeric nanoparticles are designed to transport and deliver nitric oxide (NO) into hepatic stellate cells (HSCs) for the potential treatment of both liver fibrosis and portal hypertension. The nanoparticles, incorporating NO donor molecules (S‐nitrosoglutathione compound), are designed for liver delivery, minimizing systemic delivery of NO. The nanoparticles are decorated with vitamin A to specifically target HSCs. We demonstrate, using in vitro and in vivo experiments, that the targeted nanoparticles are taken up specifically by rat primary HSCs and the human HSC cell line accumulating in the liver. When nanoparticles, coated with vitamin A, release NO in liver cells, we find inhibition of collagen I and α‐smooth muscle actin (α‐SMA), fibrogenic genes associated with activated HSCs expression in primary rat liver and human activated HSCs without any obvious cytotoxic effects. Finally, NO‐releasing nanoparticles targeted with vitamin A not only attenuate endothelin‐1 (ET‐1) which elicites HSC contraction but also acutely alleviates haemodynamic disorders in bile duct‐ligated‐induced portal hypertension evidenced by decreasing portal pressure (≈20%) and unchanging mean arterial pressure. This study clearly shows, for the first time, the potential for HSC targeted nanoparticle delivery of NO as a treatment for liver diseases with proven efficacy for alleviating both liver fibrosis and portal hypertension.     

Sm0.5Sr0.5CoO3 + Sm0.2Ce0.8O1.9 composite cathode for cermet supported thin Sm0.2Ce0.8O1.9 electrolyte SOFC operating below 600 °C

The cathode is a key component in low temperature solid oxide fuel cells. In this study, composite cathode, 75 wt.% Sm_0.5Sr_0.5CoO₃ (SSC) + 25 wt.% Sm_0.2Ce_0.8O_1.9 (SDC), was applied on the cermet supported thin SDC electrolyte cell which was fabricated by tape casting, screen-printing, and co-firing. Single cells with the composite cathodes sintered at different temperatures were tested from 400 to 650 °C. The best cell performance, 0.75 W cm⁻² peak power operating at 600 °C, was obtained from the 1050 °C sintered cathode. The measured thin SDC electrolyte resistance R_s was 0.128 Ω cm² and total electrode polarization R_p(a + c) was only 0.102 Ω cm² at 600 °C.     

Noncovalent functionalization of carbon nanotubes with amphiphilic gd3+ chelates: toward powerful t1 and t2 MRI contrast agents

An amphiphilic gadolinium (III) chelate (GdL) was synthesized from commercially available stearic acid. Aqueous solutions of the complex at different concentrations (from 1 mM to 1 microM) were prepared and adsorbed on multiwalled carbon nanotubes. The resulting suspensions were stable for several days and have been characterized with regard to magnetic resonance imaging (MRI) contrast agent applications. Longitudinal water proton relaxivities, r1, have been measured at 20, 300, and 500 MHz. The r1 values show a strong dependence on the GdL concentration, particularly at low field. The relaxivities decrease with increasing field as it is predicted by the Solomon-Bloembergen-Morgan theory. Transverse water proton relaxation times, T2, have also been measured and are practically independent of both the frequency and the GdL concentration. An in vivo feasibility MRI study has been performed at 300 MHz in mice. A negative contrast could be well observed after injection of a suspension of functionalized nanotubes into the muscle of the leg of the mouse.     

Strong magneto-chiral dichroism in enantiopure chiral ferromagnets

As materials science is moving towards the synthesis, the study and the processing of new materials exhibiting well-defined and complex functions, the synthesis of new multifunctional materials is one of the important challenges. One of these complex physical properties is magneto-chiral dichroism which arises, at second order, from the coexistence of spatial asymmetry and magnetization in a material. Herein we report the first measurement of strong magneto-chiral dichroism in an enantiopure chiral ferromagnet. The ab initio synthesis of the enantiopure chiral ferromagnet is based on an enantioselective self-assembly, where a resolved chiral quaternary ammonium cation imposes the absolute configurations of the metal centres within chromium-manganese two-dimensional oxalate layers. The ferromagnetic interaction between Cr(III) and Mn(II) ions leads to a Curie temperature of 7 K. The magneto-chiral dichroic effect is enhanced by a factor of 17 when entering into the ferromagnetic phase.     

Hydrogen-bond relays in concerted proton-electron transfers

Reaction mechanisms in which electron and proton transfers are coupled are central to a huge number of processes, both natural and synthetic. Moreover, most of the new approaches to address modern energy challenges involve proton-coupled electron transfer (PCET). Recent research has focused on the possibility that the two steps are concerted, that is, concerted proton-electron transfer (CPET) reactions, rather than stepwise pathways in which proton transfer precedes (PET) or follows (EPT) electron transfer. CPET pathways have the advantage of bypassing the high-energy intermediates of stepwise pathways, although this thermodynamic benefit may have a kinetic cost. Concerted processes require short distances between the group being oxidized and the proton acceptor (and vice versa for a reduction process), which usually involves the formation of a hydrogen bond. Unlike the electron in outer-sphere electron-transfer reactions, the distance a proton may travel in a CPET is therefore rather limited. The idea has recently emerged, however, that this distance may be substantially increased via a H-bond relay located between the electron-transfer-triggered proton source and the proton acceptor. Generally speaking, the relay is a group bearing a H atom able to accept a H-bond from the moiety being oxidized and, at the same time, to form a H-bond with the proton-accepting group without going through a protonated intermediate. Although these molecules do not retain all the properties of chains of water molecules engaged in Grotthuss-type transport of a proton, the OH group in these molecules does possess a fundamental property of water molecules: namely, it is both a hydrogen-bond acceptor and a hydrogen-bond donor. Despite centuries of study, the mechanisms of proton movement in water remain active experimental and theoretical research areas, but so far with no connection to CPET reactions. In this Account, we bring together recent results concerning (i) the oxidative response of molecules containing a H-bond relay and (ii) the oxidation of phenol with water (in water) as the proton acceptor. In the first case, a nondestructive electrochemical method (cyclic voltammetry) was used to investigate the oxidation of phenol molecules containing one H-bond relay and an amine proton acceptor compared with a similar amino phenol deprived of relay. In the second, the kinetics of phenol oxidation with water (in water) as proton acceptor is contrasted with that of conventional proton acceptors (such as hydrogen phosphate and pyridine) to afford evidence of the concerted nature of Grotthuss-type proton displacement with electron transfer. First indications were provided by the same electrochemical method, whereas a more complete kinetic characterization was obtained from laser flash photolysis. Older electrochemical results concerning the reduction of superoxide ion in the presence of water are also examined. The result is a timely picture of current insight into concerted mechanisms involving electron transfer coupled with proton transport over simple H-bond relays and over H-bond networks.     

High performance metal-supported solid oxide fuel cells fabricated by thermal spray

Metal-supported solid oxide fuel cells (SOFCs) have been fabricated and characterized in this work. The cells consist of porous NiO-SDC as anode, thin SDC as electrolyte, and SSCo as cathode on porous stainless steel substrate. The anode and electrolyte layers were consecutively deposited onto porous metal substrate by thermal spray, using standard industrial thermal spray equipment, operated in an open-air atmosphere. The cathode materials were applied to the as-sprayed half-cells by screen-printing and heat-treated at 800 °C for 2 h. The cell components and performance were examined by scanning electron microscopy (SEM), X-ray diffraction, leakage test, ac impedance and electrochemical polarization at temperatures between 500 and 700 °C. The half-inch button cells exhibit a maximum power density in excess of 0.50 W cm⁻² at 600 °C and 0.92 W cm⁻² at 700 °C operated with humidified hydrogen fuel, respectively. The half-inch button cell was run at 0.5 A cm⁻² at 603 °C for 100 h. The cell voltage decreased from 0.701 to 0.698 V, giving a cell degradation rate of 4.3% kh⁻¹. Impedance analysis indicated that the cell degradation included 4.5% contribution from ohmic loss and 1.4% contribution from electrode polarization. The 5 cm × 5 cm cells were also fabricated under the same conditions and showed a maximum power density of 0.26 W cm⁻² at 600 °C and 0.56 W cm⁻² at 700 °C with dry hydrogen as fuel, respectively. The impedance analysis showed that the ohmic resistance of the cells was the major polarization loss for all the cells, while both ohmic and electrode polarizations were significantly increased when the operating temperature decreased from 700 to 500 °C. This work demonstrated the feasibility for the fabrication of metal-supported SOFCs with relatively high performance using industrially available deposition techniques. Further optimization of the metal support, electrode materials and microstructure, and deposition process is ongoing.