Response of a direct methanol fuel cell to fuel change

Methanol and ethanol have recently received much attention as liquid fuels particularly as alternative ‘energy-vectors’ for the future. In this sense, to find a direct alcohol fuel cell that able to interchange the fuel without losing performances in an appreciable way would represent an evident advantage in the field of portable applications. In this work, the response of a in-house direct methanol fuel cell (DMFC) to the change of fuel from methanol to ethanol and its behaviour at different ambient temperature values have been investigated. A corrosion study on materials suitable to fabricate the bipolar plates has been carried out and either 316- or 2205-duplex stainless steels have proved to be adequate for using in direct alcohol fuel cells. Polarization curves have been measured at different ambient temperature values, controlled by an experimental setup devised for this purpose. Data have been fitted to a model taking into account the temperature effect. For both fuels, methanol and ethanol, a linear dependence of adjustable parameters with temperature is obtained. Fuel cell performance comparison in terms of open circuit voltage, kinetic and resistance is established.     

Micro–macro interactions and effect of section thickness of hpdc AZ91 Mg alloy

This work is aimed to conclude the effect of section thickness of a high pressure die cast (hpdc) Mg alloy on the tensile properties as ambiguous conclusions are presented in the literature. Tensile tests were performed on as-cast hpdc AZ91 alloy and the effect of section thickness on the tensile properties such as yield strength (YS), ultimate tensile strength (UTS), ductility and fracture strain (FS) are explained. Additionally, explanation on the microfailure mode of the material is presented to explain the influence of different microfeatures on the failure process. The average size, area fraction and clustering tendency of pores and Mg₁₇Al₁₂ (β) particles as well as average grain size are quantified and their effects on section thickness are obtained. The results confirm that the UTS, YS, ductility and FS are mainly influenced by the area fraction, size distribution and spatial arrangement of pores and phases.     

Multiphase poroelastic modeling in semi-space for deformable reservoirs

Field observations suggest that while pressure depletion is a local process that occurs dominantly in reservoirs being exploited, it triggers a redistribution of effective stress in a more extensive domain that involves not just the adjacent strata, but the entire overburden and surrounding rocks out to considerable distances. In an infinite or semi-infinite domain, a petroleum reservoir can be simulated as a displacement discontinuity, permitting use of an efficient displacement discontinuity boundary element method to calculate surrounding stress and displacement changes. A 3D poroelastic finite element method is used to account for the local reservoir model. By coupling the displacement discontinuity and finite element models, a 3D poroelastic reservoir in an infinite or semi-infinite domain is simulated. The numerical model has been verified and numerical examples are given. Results show that the relative deformation properties of surrounding strata have significant effects on pressure drawdown and reservoir deformation during production, and thus should be taken into account.     

Improved creaminess of low-fat yoghurt: The impact of amylomaltase-treated starch domains

Amylomaltase-treated starch (ATS) is an excellent creaminess enhancer in yoghurt. Small amounts of ATS raised the creaminess perception of low-fat yoghurt (1.5%) to that of full-fat yoghurt (5%). In this way, a reduction in fat-related energy value could be achieved from 45 to 21.5 kcal/100 g product. The functionality of ATS in set yoghurt resulted from discrete domains of ATS that resemble the microstructural behaviour of fat particles. The microstructure of the yoghurt is dominated by the protein and the ATS domains are enclosed in or bound to this protein network. The perceived creaminess resulted from in-mouth melting of these ATS domains due to a combined effect of their physical melting and hydrolysis by amylase present in the saliva.     

Curvature prediction in air bending of metal sheet

The paper describes the use of bending models for air bending and focuses in particular on the importance of adequate determination of sheet curvatures, especially the curvature under the punch nose. After an introduction to air bending, the principles of models which are based on the assumption that the sheet wraps around the punch are described. This ‘wrap-around’ assumption is a limitation and often not in accordance with industrial practice. A method to predict the sheet curvature under the punch, thus eliminating the need for the wrap-around assumption, is discussed and its results are compared with experimental results. The paper then describes how models based on this method can be used to improve adaptive control methods in air bending.     

Facile Synthesis and Characterization of Palm CNF-ZnO Nanocomposites with Antibacterial and Reinforcing Properties

Cellulose nanofibers (CNF) isolated from plant biomass have attracted considerable interests in polymer engineering. The limitations associated with CNF-based nanocomposites are often linked to the time-consuming preparation methods and lack of desired surface functionalities. Herein, we demonstrate the feasibility of preparing a multifunctional CNF-zinc oxide (CNF-ZnO) nanocomposite with dual antibacterial and reinforcing properties via a facile and efficient ultrasound route. We characterized and examined the antibacterial and mechanical reinforcement performances of our ultrasonically induced nanocomposite. Based on our electron microscopy analyses, the ZnO deposited onto the nanofibrous network had a flake-like morphology with particle sizes ranging between 21 to 34 nm. pH levels between 8–10 led to the formation of ultrafine ZnO particles with a uniform size distribution. The resultant CNF-ZnO composite showed improved thermal stability compared to pure CNF. The composite showed potent inhibitory activities against Gram-positive (methicillin-resistant Staphylococcus aureus (MRSA)) and Gram-negative Salmonella typhi (S. typhi) bacteria. A CNF-ZnO-reinforced natural rubber (NR/CNF-ZnO) composite film, which was produced via latex mixing and casting methods, exhibited up to 42% improvement in tensile strength compared with the neat NR. The findings of this study suggest that ultrasonically-synthesized palm CNF-ZnO nanocomposites could find potential applications in the biomedical field and in the development of high strength rubber composites.     

Controlled p-doping of pigment layers by cosublimation: Basic mechanisms and implications for their use in organic photovoltaic cells

We present a systematic study on doping of vanadyl- and zinc-pathalocyanine by a fully fluorinated form of tetracyano-quinodimethane as an example of controlled doping of thin organic films by cosublimation of matrix and dopant. The films are characterized in situ by temperature dependent Seebeck and conductivity measurements. We observe a drastic increase of conductivity and a corresponding shift of the Fermi level towards the valence states with increasing dopant concentration. We thus conclude that doping has the potential of both reducing the series resistance and increasing the photovoltage of organic solar cells. As a first step to exploit this potential, we present two different ways of preparing diodes with rectification ratios in excess of 10⁴ using doped phthalocyanines. By adding an undoped interlayer between the contact and the doped layer, we have produced diodes which work already in the strict absence of oxygen and are stable in air. To increase the efficiency of charge carrier generation in photovoltaic cells, we need to use photoactive donor–acceptor-heterojunctions. We present here first examples of pn- and pin-type heterojunctions combining p-doped and nominally undoped layers.