X-ray computed tomography reconstruction and analysis of polymer electrolyte membrane fuel cell porous transport layers

A commercially available porous transport layer (SGL carbon group Sigracet^® GDL 30BA), is investigated using X-ray computed tomography reconstruction. A novel aspect of this study is an investigation of the effects of non-homogeneous compression of the GDL 30BA sample including effective transport properties. Non-homogeneous compression is typical in polymer electrolyte fuel cells as the flow field plates consist of a series of lands and channels which apply an uneven loading to the porous transport layers. The X-ray computed tomography technique provides input data for the computer reconstruction procedures integrating image post-processing and iso-surface reconstruction. The resulting tomographic and surface reconstruction is converted into the computational volume/grid for microstructural and computational fluid dynamics (CFD) analysis. The heterogeneous compression effects on effective geometric and transport properties are investigated for various compression levels and effective transport properties are compared to theoretical studies such as Bruggeman [1] and Tomadakis and Sotirchos [2]. The effects of non-homogeneous compression are significant, with the transport properties differing by a factor of about 2 between the land and the channel regions. It is found that the effective transport properties are significantly lower than predicted by commonly used relations, with the lowest values representing only 15% of the predictions from the Bruggeman relation.     

What’s in a name? The effects of sound symbolism and package shape on consumer responses to food products

In the global market, consumers are exposed to multiple brand names in unfamiliar languages. Even meaningless words can trigger certain semantic associations. This phenomenon is known as sound symbolism, i.e., the direct link between a sound and a meaning. Sound symbolism helps consumers to form product expectations based on unfamiliar brand names. Product expectations can be also formed based on various elements of packaging design, including colours, shapes and materials. This study investigated the effects of unfamiliar brand names (“Asahi” vs. “Ramune”), package shapes (round vs. angular) and product types (muesli cookie vs. butter cookie) varied in perceived healthiness (low vs. high) on perceived product healthfulness, product evaluation, taste expectations and purchase intention. General health interest (GHI) was used as the moderating variable. The results showed that package shape and product type significantly influenced the perceived product healthfulness of the two experimental products. Brand name alone did not affect consumer responses. However, the congruent combination of product shape and brand name (round “Ramune” cookie) was preferred to incongruent combinations. Furthermore, the congruent combinations (“Ramune” butter cookie and “Asahi” muesli cookie) were expected to taste better and were more likely to be purchased compared to incongruent combinations. These results suggest that congruency between the type of product, brand name, and package design is important for creating a successful brand strategy. The study also showed that the effects of sound symbolism and congruency on perceived product healthfulness are more pronounced for consumers with low interest in healthy eating. However, further research is needed to generalise our results to other product groups.     

Surface shape measurement of mirrors in the form of rotation figures by using point diffraction interferometer

The paper deals with the use of a point diffraction interferometer (PDI) to study the surface shape of rotation figures. The relations are given for the correspondence of the coordinates on the surfaces of an ellipsoid, a paraboloid and a hyperboloid as well as on an interferogram. Using PDI and Zygo white-light interferometer (WLI), we experimentally investigated the surface shape of the grazing incidence ellipsoid with the multilayer reflective coating on a wavelength of 0.154 nm with the following parameters: length is 55 mm, half-axis are 6 and 235 mm. The results coincided with an accuracy of 73 nm (RMS) without taking into account the PDI lateral resolution, and with an accuracy of 50 nm (RMS) with taking it into account, which ensures the local angles measurement accuracy of the ellipsoid-shaped reflecting surface at a level of 3 μrad. We think that this difference may be attributed to the limited lateral resolution of PDI and errors of frames stitching of WLI; nevertheless, we do believe that the PDI measurement accuracy is in the range of sub-μrad.     

Durable superoleophobic fabric surfaces with counterintuitive superwettability for polar solvents

Smart superoleophobic (SOP) cotton fabric surfaces are created only through a controlled fluorosilanization treatment, exhibiting the first‐ever extreme wetting behaviors displaying ultrarepellency to nonpolar oils and counterintuitive superwettability for all polar solvents. The smart durable SOP surfaces, demonstrated chemically, thermally, and mechanically, render great potential practical and industrial applications in robust oil shielding, effective antifouling, highly energy efficient self‐cleaning, and solely gravity‐driven oil–water separations. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2752–2756, 2014     

Graphene network enabled high speed electrical actuation of shape memory nanocomposite based on poly(vinyl acetate)

Here strong electroactive shape memory nanocomposites were prepared by incorporating graphene nanoplatelets into poly(vinyl acetate) (PVAc ) through the simple solvent mixing method. TEM and XRD revealed that well exfoliated graphene nanoplatelets formed a continuous network throughout the matrix with a large amount of interconnectedness. Dynamic mechanical analysis showed that the inclusion of graphene significantly improves both glassy and rubbery moduli of the matrix. Furthermore, the prepared nanocomposites demonstrated a marked electrical conductivity up to 24.7 S m^?1 and thereby surprisingly rapid electrical actuation behaviour exhibiting a 100% recovery ratio in 2.5 s. Moreover, PVAc and its nanocomposites displayed scratch self‐healing capability. This work demonstrates that the PVAc /graphene nanocomposites with high modulus and excellent electroactive shape memory performance can be a promising material in many applications such as sensors and fast deployable and actuating devices. © 2016 Society of Chemical Industry     

Electroseparation of an antibacterial peptide fraction from snow crab by-products hydrolysate by electrodialysis with ultrafiltration membranes

Recently, a snow crab by-products hydrolysate has demonstrated antibacterial properties due to a peptide with a molecular weight of about 800 Da, but only at high concentration. Consequently, peptide hydrolysate has been fractionated to obtain peptides in a more purified form. The aim of this work was to separate a snow crab by-products hydrolysate by electrodialysis with ultrafiltration membranes (EDUF). EDUF, which allows separation of molecules according to their charges and molecular weights, was used to recover and concentrate the active antibacterial fraction. Two different ultrafiltration membranes (20 and 50 kDa) and two electrical field strengths (2 and 14 V/cm) were used as separation parameters. After EDUF separation, the 300-600 Da peptide molecular weight range was the most recovered with an abundance of 94%. Moreover, fractionation at 14 V/cm with ultrafiltration membranes of 50 kDa allowed the recovery of an anionic fraction which showed antibacterial properties on Escherichia coli ATCC 25922 and Listeria innocua HPB 13.     

Synthesis and Characterization of Microporous ZrO2 Membranes for Gas Permeation at 200°C

The development of gas separation membranes able to work at high temperatures require robust and thin ceramic layers. In this work, zirconia membranes have been prepared by the sol-gel method, following the colloidal sol route. The microporosity and crystallinity of the ZrO₂ material was tested by N₂ adsorption and XRD. The derived active zirconia layers were defect-free as seen by SEM. The optimum firing temperature range was set in the range 400–500°C. He, H₂, CO₂, N₂ gas permeation was conducted at temperatures up to 200°C. High permeances were obtained and the microporosity of the zirconia layer was confirmed.     

Novel Polysilsesquioxane Hybrid Membranes for Proton Exchange Membrane Fuel Cell (PEMFC) Applications

Abstract

Novel polysilsesquioxane (R–Si–(O)_1.5) PEMs with highly cross-linked Si–O backbones and pendant organic side chains comprising propylsulfonic or ethylphosphonic acid groups, were prepared via sol-gel polymerization. The inorganic component provides thermal/mechanical/chemical stability while the organic component gives flexibility and proton-conducting properties. The propylsulfonic acid membranes exhibited proton conductivities (σ) up to 10^?2 S/cm at high relative humidities and temperatures, while the ethylphosphonic acid membranes showed lower proton conductivities but higher thermal stabilities. Preliminary results for the propylsulfonic acid membranes in direct methanol fuel cell (DMFC) performance are reported.     

Chitosan disrupts Penicillium expansum and controls postharvest blue mold of jujube fruit

Chitosan has been shown to be effective for control of postharvest diseases on various fruit. However, little is known about the effect of chitosan on blue mold caused by Penicillium expansum on jujube fruit. Here we show that application of chitosan reduced disease development of blue mold caused by P. expansum in wounded and inoculated jujube fruit at 25 °C. Chitosan also provided an inhibitory effect on natural decay of jujube fruit during storage at 0 °C. Application of a chitosan coating to fruit had hardly any significant effect on the changes of weight loss, soluble solid contents, titratable acidity, and vitamin C, as storage time increased. To investigate the mechanisms underlying the effectiveness of chitosan against blue mold on jujube fruit, we analyzed the growth of P. expansum after chitosan treatment. Results indicated that spore germination, germ tube length and mycelial growth of P. expansum were significantly inhibited by chitosan in a concentration-dependent mode. Using the fluorescent probe propidium iodide, we found that the plasma membrane of P. expansum collapsed significantly after chitosan treatment. Further observation by electron microscopy revealed that plasma membrane of P. expansum was gradually disrupted after chitosan application. Our data suggest that chitosan may be potentially used for controlling postharvest diseases in jujube fruit without negative effect on fruit quality.     

Electromagnetically induced transparency in a quadratically coupled optomechanical system with an atomic medium

We investigate a quadratically coupled optomechanical cavity system filled with a two-level atomic medium. The output of the cavity field exhibits analogous electromagnetically induced transparency when the optomechanical system interacts with the coupling and probe fields, respectively. We show that the introduction of the atomic medium can enhance the fluctuation of the displacement of the membrane as well as its energy. With the increasing of the atomic number, the dip of the absorption becomes deep.