Data collection: evaluation of a pilot model

The overall purpose of this study was to explore nurses' feelings about the applicability and adequacy of a pilot model of nursing assessment (PMNA) developed for coronary care units (CCU) in order to obtain data that could help in establishing a definitive model. The evaluation, performed by 11 CCU nurses, showed that they considered the development and implementation of PMNA as valuable, and that its design was adequate for interviewing cardiac patients. These results will be employed in the elaboration of a definitive model of nursing assessment.     

Protein Folding and Aggregation into Amyloid: The Interference by Natural Phenolic Compounds

Amyloid aggregation is a hallmark of several degenerative diseases affecting the brain or peripheral tissues, whose intermediates (oligomers, protofibrils) and final mature fibrils display different toxicity. Consequently, compounds counteracting amyloid aggregation have been investigated for their ability (i) to stabilize toxic amyloid precursors; (ii) to prevent the growth of toxic oligomers or speed that of fibrils; (iii) to inhibit fibril growth and deposition; (iv) to disassemble preformed fibrils; and (v) to favor amyloid clearance. Natural phenols, a wide panel of plant molecules, are one of the most actively investigated categories of potential amyloid inhibitors. They are considered responsible for the beneficial effects of several traditional diets being present in green tea, extra virgin olive oil, red wine, spices, berries and aromatic herbs. Accordingly, it has been proposed that some natural phenols could be exploited to prevent and to treat amyloid diseases, and recent studies have provided significant information on their ability to inhibit peptide/protein aggregation in various ways and to stimulate cell defenses, leading to identify shared or specific mechanisms. In the first part of this review, we will overview the significance and mechanisms of amyloid aggregation and aggregate toxicity; then, we will summarize the recent achievements on protection against amyloid diseases by many natural phenols.     

Composite short-side-chain PFSA electrolyte membranes containing selectively modified halloysite nanotubes (HNTs)

Aquivion membrane displays improved properties as compared to Nafion membrane, partly due to shorter side chains. However, some improvements are still necessary for proton exchange membrane fuel cell to operate at low relative humidity. To overcome this drawback, the addition of clay nanoparticle into the Aquivion matrix can be considered. In this study, different composite membranes have been prepared mixing short-side-chain PFSA (perfluorosulfonic acid) Aquivion and selectively modified halloysite nanotubes for PEMFC low relative humidity operation. Halloysites were grafted with fluorinated groups, sulfonated groups, or perfluoro-sulfonated groups on inner or outer surface of the tubes. The obtained composite membranes showed improved properties, especially higher water uptake associated with reduced swelling and better mechanical strength compared to pristine Aquivion membrane and commercially available Nafion HP used as reference. The best performance in this study was obtained with Aquivion loaded with 5 wt% of pretreated perfluoro-sulfonated halloysite. The composite membrane, referred to as Aq/pHNT-SF5, displayed the largest water uptake and proton conductivity among the panel of membranes tested. The chemical stability was not affected by the presence of halloysite in the Aquivion matrix.

Graphical abstract

     

Impact of three different TiO2 morphologies on hydrogen evolution by methanol assisted water splitting: Nanoparticles, nanotubes and aerogels

Increasing the activity of a photocatalyst goes through the improvement of both its absorption (light) and adsorption (reactant) properties. For a given semiconducting material, the charge carrier separation is also a very important step. Properly combining chosen phases is one option to improve this separation (example of the commercial P25) and depositing platinum on the surface of the catalyst, another one. In some cases, coupling both may nevertheless lead to a decrease of photoactivity or at least limit the potentiality of the catalyst. A third option, consisting in modifying the morphology of the photoactive phase, has shown very promising results.In this study, we have elaborated, characterized and evaluated the hydrogen evolution potentiality (through methanol assisted water splitting) of different TiO₂ morphologies: nanoparticles, nanotubes and aerogels. These materials have shown different behaviours depending on both their composition and morphology. Different types of separation processes have been claimed to account for the observed different photoactivities, with more or less pronounced synergetic effects, due to: the use of Pt as a co-catalyst, the mixture of different TiO₂ phases (anatase and TiO₂(B) or rutile) and the specific morphology of the samples (nanotubes or aerogels). Among all the tested samples, the TiO₂ aerogel supported Pt one exhibited very promising performances, three times as active as P25 supported Pt, which is already much more active than pure P25 in our testing conditions.     

The low-molecular-weight phosphotyrosine protein phosphatase, when overexpressed, reduces the mitogenic response to macrophage colony-stimulating factor and tyrosine phosphorylation of its receptor

Inert gases at raised pressure exert anaesthetic effects. It is assumed that anaesthesia by the inert gases is fundamentally similar to anaesthesia produced by general anaesthetics. However, do general anaesthetics bind directly to proteins or influence activity by indirectly perturbing membrane lipids still remains a major question. Although the pressure required to achieve anaesthesia with inert gases has been suggested to exert potentially some pressure antagonism per se, this has not been studied yet to our knowledge. We investigated this possibility using nitrogen, argon, and nitrous oxide. Whatever the narcotic agent used, our results showed that the pressure of narcotic required to induce anaesthetic effects increased, as compression rate increased, in a sigmoid fashion rather than in a linear fashion. Evidence for sigmo?dal responses vs. linear responses depended of the narcotic potency of the anaesthetic agent used (nitrogen: r2=0.973 vs. r2=0.941; argon: r2=0. 971 vs. r2=0.866; nitrous oxide: r2=0.995 vs. r2=0.879). Since a linear antagonism is predicted by lipid theories, we think it likely that these findings indicate that inert gases bind to a modulatory site of a protein receptor and act as allosteric modulators. Since other workers provided evidence for binding processes using volatile anaesthetics, the present findings could indicate that all classes of general anaesthetics, including inert gases, could act by binding directly to proteins rather than by dissolving in some lipids of the cellular membrane.     

New nanostructured carbons based on porous cellulose: Elaboration,pyrolysis and use as platinum nanoparticles substrate for oxygen reduction electrocatalysis

New nanostructured carbons have been prepared from pyrolysis of recently developed highly porous cellulose, aerocellulose (AC). Aerocellulose is an ultra-light and highly porous pure cellulose material prepared from cellulose gels followed by drying in carbon dioxide supercritical conditions. The carbonized aerocellulose (CAC) materials were obtained after pyrolysis of the aerocellulose under nitrogen flow at 830 °C, and subsequently doped by platinum nanoparticles. The platinum insertion process consisted of (i) thermal activation at various temperatures in CO₂ atmosphere, (ii) impregnation by PtCl₆²⁻ and (iii) platinum salt chemical reduction. The aerocellulose materials and their carbonized counterparts were investigated by scanning and transmission electron microscopy (SEM and TEM), mercury porosimetry and thermogravimetric analysis. The morphology of the platinum particles deposited on the carbonized aerocellulose materials (Pt/CAC) was investigated by transmission electron microscopy (TEM) and X-ray diffraction (XRD): the Pt particles are of 4–5 nm size, mainly agglomerated, as a result of the complex surface chemistry of the CAC. Their electrocatalytic activity was investigated by quasi-steady-state voltammetry in the rotating disk electrode (RDE) setup, regarding the oxygen reduction reaction (ORR). The Pt/CAC materials exhibit ORR specific activities comparable with those of commercial Pt/Vulcan XC72R. Their mass activity is lower, as a result of the ca. 10 times smaller specific area of platinum as compared with the commercial electrocatalyst. We nevertheless believe that provided an appropriate pyrolysis temperature is chosen, such green carbonized aerocellulose could be a promising electrocatalyst support for PEM application.     

Cellulose-based aerogels

New organic aerogels were prepared using cellulose derivatives as precursors. The elaboration process and the structural characterisations of these porous cellulose-based materials are described in the present study. Series of monolithic gels were synthesised in acetone by crosslinking cellulose acetate with a non-toxic isocyanate via sol-gel route, using tin-based catalyst. Gelation times (ranging from 15 to 150 min) were significantly dependent on reagents' nature and concentration. Low-density materials (from 0.25 cm³/g to 0.85 cm³/g) were obtained after supercritical carbon dioxide drying. These newly developed nanostructured materials were characterised using mercury porosimetry, nitrogen adsorption and scanning electron microscopy. All the prepared materials have shown both a nanostructured solid network (specific surface areas between 140 and 250 m²/g) and a nanoporous network (characteristic pore sizes between 13 and 25 nm) together with specific porous volumes as large as 3.30 cm³/g.Influence of sol-gel synthesis parameters as crosslinker content and cellulose degree of polymerisation or concentration was investigated. First empirical correlations between synthesis parameters and final material properties were obtained. A special attention was dedicated to the different shrinkages occurring during the elaboration process. In particular, the important shrinkage occurring during the supercritical drying step was studied in terms of affinity between the crosslinked polymeric network and carbon dioxide. In parallel, first thermo-mechanical properties were presented in terms of bulk modulus and effective thermal conductivity.     

Use of cellulose-based carbon aerogels as catalyst support for PEM fuel cell electrodes: Electrochemical characterization

New nanostructured carbons have been developed through pyrolysis of organic aerogels, based on supercritical drying of cellulose acetate gels. These cellulose acetate-based carbon aerogels (CA) are activated by CO₂ at 800 °C and impregnated by PtCl₆²⁻; the platinum salt is then chemically or electrochemically reduced. The resulting platinized carbon aerogels (Pt/CA) are characterized with transmission electron microscopy (TEM) and electrochemistry. The active area of platinum is estimated from hydrogen adsorption/desorption or CO-stripping voltammetry: it is possible to deposit platinum nanoparticles onto the cellulose acetate-based carbon aerogel surface in significant proportions. The oxygen reduction reaction (ORR) kinetic parameters of the Pt/CA materials, determined from quasi-steady-state voltammetry, are comparable with that of Pt/Vulcan XC72R. These cellulose acetate-based carbon aerogels are thus promising electrocatalyst support for PEM application.