Toward optimization of a robust low-cost sulfonated-polyethersulfone containing layered double hydroxide for PEM fuel cells

Polyethersulphone (PES) is an aromatic thermoplastic, at low environmental impact, evaluated in this work as a promising candidate for new polymer electrolytes in the PEMFCs technology. A sulfonation procedure has been tuned in order to graft sulfonic acid groups on the polymer chains (sPES) and to make it hydrophilic. Homogeneous membranes with different polymer's sulfonation degrees (SD%) have demonstrated excellent mechanical properties and very low permeability toward methanol (important in the DMFCs), even if low proton conductivity. Nanocomposite sPES membranes were prepared by dispersion of highly hydrophilic lamellar particles such as layered double hydroxide (LDH) in the polymer. Deep investigations performed by a combination of PFG-NMR, EIS, XRD, DMA, and scanning electron microscopy have evidenced the exfoliation of the lamellae in polymer matrix. However, a certain anisotropy was evidenced both in the morphology and molecular diffusion, favored in the longitudinal direction (parallel to surface), while completely inhibited in the cross-section. This finding is most likely induced by the polymer structure, therefore particular attention must be paid to the choice of the filler and preparation of the composites. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47884.     

From the individual element test to finite element templates: Evolution of the patch test

This paper starts a sequence of three articles that follow an unconventional approach in finite element research. The ultimate objective is to construct high-performance elements and element-level error estimators for those elements. The approach takes off from our previous work in high-performance elements and culminates with the development of finite element templates. The present paper concentrates on the patch test and evolved versions of the test that have played a key role in this research. Following a brief review of the historical roots, we present the Individual Element Test (IET) of Bergan and Hanssen in an expanded context that encompasses several important classes of new elements. The relationship of the IET to the multielement forms A, B and C of the patch test and to the single-element test are investigated. An important consequence of the IET application is that the element stiffness equations decompose naturally into basic and higher-order parts. The application of this decomposition to the “sanitization” of the non-convergent BCIZ element is described and verified with numerical experiments. Two sequel papers in preparation are subtitled ‘the algebraic approach’ and ‘element-level error estimation’. These apply the fundamental decomposition to the derivation of templates for specific mechanical elements and to the construction of element-level error estimators, respectively.     

Direct Methods Optimised for Solving Crystal Structure by Powder Diffraction Data: Limits,Strategies, and Prospects

The ab-initio crystal structure solution by powder diffraction data requires great efforts because of the collapse of the experimental information onto the one dimensional 2θ axis of the pattern. Different strategies will be described aiming at improving the process of extraction of the integrated intensities from the experimental pattern in order to make more straightforward the structure solution process by direct methods. Particular attention will be devoted to the EXPO program. Some of its performance will be analysed and results will be shown.     

Suitability of the SWAT Model for Simulating Water Discharge and Sediment Load in a Karst Watershed of the Semiarid Mediterranean Basin

Water Resources Management - This paper presents a case study conducted in the Upper Argos River, in southeast Spain, to verify the applicability of the SWAT model for prediction of the water...     

Recommendation of RILEM Technical Committee 250-CSM: Test method for Textile Reinforced Mortar to substrate bond characterization

Textile Reinforced Mortar (TRM), also known as Fabric Reinforced Mortar or Fabric Reinforced Cementitious Matrix, composites are an emerging technology for the external repair and strengthening of existing structures. For most applications, the effectiveness of the TRM reinforcement relies on its bond performance. This recommendation identifies the best practice to characterize the bond behaviour of TRM. A shear bond test method is proposed to determine the peak axial stress (associated with the maximum load that can be transferred from the structural member to the externally bonded TRM reinforcement), the stress–slip relationship and the failure mode that controls the TRM-to-substrate load transfer capacity. Guidelines on specimen manufacturing, experimental setup, test execution, and determination of test results are provided.     

A CSP model for simple non-reversible and parallel repair plans

This work presents a constraint satisfaction problem (CSP) model for the planning and scheduling of disassembly and assembly tasks when repairing or substituting faulty parts. The problem involves not only the ordering of assembly and disassembly tasks, but also the selection of them from a set of alternatives. The goal of the plan is the minimization of the total repairing time, and the model considers, apart from the durations and resources used for the assembly and disassembly tasks, the necessary delays due to the change of configuration in the machines, and to the transportation of intermediate subassemblies between different machines. The problem considers that sub-assemblies that do not contain the faulty part are nor further disassembled, but allows non-reversible and parallel repair plans. The set of all feasible repair plans are represented by an extended And/Or graph. This extended representation embodies all of the constraints of the problem, such as temporal and resource constraints and those related to the selection of tasks for obtaining a correct plan.     

Fast Separation of Capsaicinoids from Peppers by Reversed Phase Ultra-Performance Liquid Chromatography: Comparation with Traditional High-Performance Liquid Chromatography Methods

A new chromatographic method for the separation of major capsaicinoids in peppers has been developed. Nordihydrocapsaicin, capsaicin, dihydrocapsaicin, homocapsaicin, and homodihydrocapsaicin have been separated by reversed-phase ultra-performance liquid chromatography. A gradient method has been developed using two solvents: 0.1% acetic acid in water and 0.1% acetic acid in methanol. The developed method allows the full separation of capsaicinoids in less than 3 min, with high reproducibility (relative standard deviation < 4.3%) and repeatability (relative standard deviation < 3.6%). Robustness regarding the total amount of methanol in the sample was determined. Comparison with previous reversed-phase high-performance liquid chromatography methods using both monolithic and conventional columns was also studied. Finally, the method was applied in the determination of major capsaicinoids in 16 hot pepper samples produced in Spain.     

Influence of catalyst pretreatments on volatile organic compounds oxidation over gold/iron oxide

This paper reports a study on the influence of calcination pretreatments on the catalytic behaviour of the Au/iron oxide system towards the combustion of some representative volatile organic compounds (2-propanol, ethanol, methanol, acetone and toluene). The catalytic activity of Au/Fe₂O₃ samples towards the total oxidation to CO₂ has been found to be strongly dependent on the catalyst pretreatment, decreasing on increasing the calcination temperature. On the basis of characterisation data (XPS, FT-IR, XRD, BET surface area) it has been proposed that the catalytic behaviour is related to the gold state and/or the iron oxide phase. It appears plausible to suggest that the gold oxidation state and/or the particle size play a key role in the catalytic combustion of volatile organic compounds.