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Fabrication of electrodes for polymer electrolyte fuel cells is a intriguing process in which a balance between gas transport, electrical conductivity, proton transport and water managing must be optimized. In this work four different electrodes prepared by electrospray deposition have been studied using different catalytic inks, in which Nafion and epoxy doped with Graphene-Nanoplatelets were used as binders. After studying the behavior of those electrodes in a single open cathode fuel cell proton electrolyte membrane, it is clear that the addition of epoxy as binder doped with graphene, improves the performance of the fuel cell and increase the mechanical stability of the electrode avoiding the loose of catalyst during the electrode manipulation in the fuel cell assembly process and the durability of the fuel cell. To explain this behavior, an ex-situ study was carried out, in which properties such as its surface morphology, hydrophobicity and electrical and thermal conductivity of those electrodes were studied. From the results of this study, such improvement in the performance of the fuel cell was justified on the basis of the increase in the electrical conductivity, a diminution in its thermal conductivity and an enhancement of hydrophobicity (surface morphology) of the deposited catalyst layer, when an optimum quantity of epoxy is added to the catalytic ink that makes to improve the mechanical properties of those electrodes

Pathogenic bacteria have the ability to develop antibiotic resistance mechanisms. Their action consists mainly in the production of bacterial enzymes that inactivate antibiotics or the appearance of modifications that prevent the arrival of the drug at the target point or the alteration of the target point itself, becoming a growing problem for health systems. Chitosan–gold nanoparticles (Cs-AuNPs) have been shown as effective bactericidal materials avoiding damage to human cells. In this work, Cs-AuNPs were synthesized using chitosan as the reducing agent, and a systematic analysis of the influence of the synthesis parameters on the size and zeta potential of the Cs-AuNPs and their UV-vis spectra was carried out. We used a simulation model to characterize the interaction of chitosan with bacterial membranes, using a symmetric charged bilayer and two different chitosan models with different degrees of the chitosan amine protonation as a function of pH, with the aim to elucidate the antibacterial mechanism involving the cell wall disruption. The Cs-AuNP antibacterial activity was evaluated to check the simulation model.

Lyotropic nematic liquid crystals (lnlc) have attracted attention due to their resemblance to natural membranes and several technological applications. The effect of tetradecyltrimethyl ammonium chloride (TTAC) in the viscosity of a new lnlc containing also decanol, NaCl and natural lipids, was studied. In this article we study how the concentration of phospholipids, decanol and NaCl affects the bilayer and the liquid crystal/solution interface structures. 2 H-NMR quadrupole splittings and longitudinal relaxation times of several deuterated species were measured. Polarized light microscopy, transmission electron microscopy and kinematic viscosity measurements were also obtained. The structure of the bilayer is dominated by the surface charge density of TTAC. Water rotation, translation and ion solvation depend on the charge and distance from the interface. With increasing TTAC, MD predicts hydrocarbon chain inter-digitation and lipid rafts formation. This was rationalized using energy arguments.

Synovial liquid is a natural lubricant of articular joints, such as shoulders, knees and hips. Thus, the development of biocompatible lubricants that can be employed in medical prosthesis for artificial implants, and eventually in certain therapies against osteo-arthritis or rheumatoid-arthritis diseases, is of an undoubted importance. Lyotropic liquid crystals have been used in the synthesis of silica and metals containing regularly oriented nanoporous, to obtain oriented carbon nanotube materials, in several pharmaceutical applications, as membrane mimetics and in lubrication applications. In this context, a new nematic lyotropic liquid crystal has been developed based on tetradecyltrimethyl ammonium chloride (TTAC), decanol (DeOH), a natural mixture of lipids (PL) extracted from soybean and sodium chloride (NaCl), all dissolved in water. A 30% w/w increase in TTAC content respect a certain composition of reference produces a more than 24-fold increase in the macroscopic viscosity of the solution. To understand the molecular principles that explain this behavior, several experimental and theoretical studies have been carried out. In this regard, 2 H-NMR quadrupole splittings of fully deuterated sodium dodecyl sulphate (SDS-d25) introduced as molecular probe, transmission electron microscopy (TEM), freeze fracture transmission electron microscopy (FF-TEM), cryogenic transmission electron microscopy (Cryo-TEM) and polarized light microscopy (PLM) were obtained. In addition, hydrodynamic studies determined how the enhancement in viscosity requires a change in the shape of the aggregate, from circular to elliptic. Finally, molecular dynamics simulations allowed to estimate how variations in the bending modulus, kb, can explain the observed tendency of the quadrupole splittings, on the basis of a modification in the flexibility of the aggregate.

Atomic insight of langmuir monolayer: molecular dynamics simulations. The gas phase: zoom of lipid/water interface. Solid condensed phase: zoom of lipid/water interface. Gas phase: spontaneus domain formation, solid phase view of the hexagonal tail packaging . Gas phase: lipid interactions.