Conductive Materials for Proton Exchange Membrane Fuel Cell Bipolar Plates Made from PVDF,PET and Co‐continuous PVDF/PET Filled with Carbon Additives

The aim of this work was to develop and characterise electrically conductive materials for proton exchange membrane fuel cells and bipolar plates (BPPs). These BPPs were made from highly conductive blends of polyethylene terephthalate (PET) and polyvinylidene fluoride (PVDF), as matrix phase. The conductive materials were developed from carefully formulated blends composed of conductive carbon black (CB) powder and, in some cases, graphite synthetic flakes mixed with pure PET, PVDF or with PVDF/PET systems. They were first developed by twin‐screw extrusion process then compression‐molded to give BPP final shape. As the developed blends have to meet properties suitable for BPP applications, they were characterised for their rheological properties, electrical through‐plane resistivity (the inverse of conductivity), oxygen permeability, flexural and impact properties. Results showed that lower resistivity was obtained with PVDF/CB blends due to the higher interfacial energy between the PVDF matrix and CB and also the higher density and crystallinity of PVDF, compared to those of PET. It was also observed that the lowest resistivity values were obtained with mixing PVDF and PET at controlled compositions to ensure PVDF/PET co‐continuous morphology. Also, slow cooling rates helped to attain the lowest values of through‐plane resistivity for all studied blends. This behaviour was related to the higher crystallinity obtained with low cooling rates leading to smaller amorphous regions in which carbon particles are much more concentrated.     

A Backside-Illuminated Image Sensor With 200 000 Pixels Operating at 250 000 Frames per Second

In this paper, a high-speed image sensor with very high sensitivity is developed. The high sensitivity is achieved by introduction of backside illumination and charge-carrier multiplication (CCM). The high frame rate is guaranteed by installing the in situ storage image sensor (ISIS) structure on the front side. A test sensor of the BSI-ISIS has been developed and evaluated. It is shown that an image with a very low signal level embedded under the noise floor is recognizable by activating the CCM.     

A Binary-Weighted Switching and Reconfiguration-Based Programmable Gain Amplifier

In previous works, the authors reported on binary-weighted switching and reconfiguration techniques to design programmable gain amplifiers (PGAs) with a wide decibel (dB)-linear range, a small gain error, a wide 3-dB bandwidth, and high linearity. In this brief, two techniques are analyzed in more detail. Adopting the two techniques, a new low-voltage PGA version is proposed that offers a precise and process/temperature-insensitive gain and achieves a double dB-linear range with a small gain error while maintaining the same chip size, as compared with those of previous designs. Implemented in 0.18-mum CMOS, from the measurements, the proposed PGA shows a dB-linear gain range of 42 dB (-21 to 21 dB) with a gain error of less than plusmn 0.54 dB, a maximum input-referred third-order intercept point (IIP3) of 14 dBm, and a 3-dB bandwidth of 60 MHz at the maximum gain while consuming only 2.1 mA from a 1.5-V supply.     

Role of acidic sphingomyelinase in thymol‐mediated dendritic cell death

Scope : Thymol is a component of several plants with antimicrobial activity. Little is known about the effects of thymol on immune cells of the host. This study addressed the effects of thymol on dendritic cells (DCs), regulators of innate and adaptive immunity. Methods and results : Immunohistochemistry, Western blotting and fluorescence‐activated cell sorting analysis were performed in bone marrow‐derived DCs either from wild‐type mice or from mice lacking acid sphingomyelinase (ASM^?/?) treated and untreated for 24 h with thymol (2–100 μg/mL). Thymol treatment resulted in activation of ASM, stimulation of ceramide formation, downregulation of anti‐apoptotic Bcl‐2 and Bcl‐xL proteins, activation of caspase 3 and caspase 8, DNA fragmentation as well as cell membrane scrambling. The effects were dependent on the presence of ASM and were lacking in ASM^?/? mice or in wild‐type DCs treated with sphingomyelinase inhibitor amitriptyline. Conclusion : Thymol triggers suicidal DC death, an effect mediated by and requiring activation of ASM.     

Measuring the embodied energy in drinking water supply systems: a case study in the Great Lakes region

A sustainable supply of both energy and water is critical to long-term national security, effective climate policy, natural resource sustainability, and social wellbeing. These two critical resources are inextricably and reciprocally linked; the production of energy requires large volumes of water, while the treatment and distribution of water is also significantly dependent upon energy. In this paper, a hybrid analysis approach is proposed to estimate embodied energy and to perform a structural path analysis of drinking water supply systems. The applicability of this approach is then tested through a case study of a large municipal water utility (city of Kalamazoo) in the Great Lakes region to provide insights on the issues of water-energy pricing and carbon footprints. Kalamazoo drinking water requires approximately 9.2 MJ/m(3) of energy to produce, 30% of which is associated with indirect inputs such as system construction and treatment chemicals.     

A role for water molecules in DNA-ligand minor groove recognition

Targeting the minor groove of DNA through binding to a small molecule has long been considered an important molecular-recognition strategy in biology. A wide range of synthetic heterocyclic molecules bind noncovalently in the minor groove of the double helix and are also effective against a number of human and animal diseases. A classic structural concept, the isohelicity principle, has guided much of this work: such heterocyclic molecules require a shape that complements the convex surface of the minor groove. Researchers have used this principle to design molecules that can read DNA sequences. This principle also predicts that molecules that lack the complementary shape requirement would only bind weakly to DNA. Recently, however, researchers have unexpectedly found that some essentially linear compounds, which do not have this feature, can have high DNA affinity. In this Account, we discuss an alternative recognition concept based on these new findings. We demonstrate that highly structured water molecules can play a key role in mediating between the ligand and DNA minor groove without loss of binding affinity. Combined structural and thermodynamic approaches to understanding the behavior of these molecules have shown that there are different categories of bound water in their DNA complexes. For example, application of this water-bridging concept to the phenylamidine platform has resulted in the discovery of molecules with high levels of biological activity and low nonspecific toxicity. Some of these molecules are now in advanced clinical trials.     

Electric field induced reversible switch in hydrogen storage based on single-layer and bilayer graphenes

In an ideal hydrogen storage system, binding strength should increase during adsorption whereas the opposite should be the case during desorption. These two seemingly contradictory requirements limit the types of systems that can be utilized. Density-functional theory (DFT) calculations are carried out to investigate hydrogen physisorption on Li-doped single-layer and bilayer graphenes. We propose that the superimposition of an electric field can be used to effectively control hydrogen adsorption. More specifically, we report that hydrogen binding can be enhanced under a positive electric field, whereas it can be weakened under a negative electric field. Our results show that the binding strength increases by 88% when a field with a magnitude of +0.020 au is imposed. Hirshfeld charge analysis results suggest that an increase in the binding strength will occur as long as the Li (or C) carries more positive (or negative) charges. Our calculations demonstrate that, in the case of Li-doped graphene, the application of a positive electric field yields an increase in binding strength during adsorption while a negative field decreases the binding strength during desorption.     

Adsorption of rotavirus and bacteriophage MS2 using glass fiber coated with hematite nanoparticles

Batch and flow-through experiments were conducted to investigate the removal and inactivation of rotavirus (RV) and bacteriophage MS2 using glass fiber coated with hematite nanoparticles. Batch tests showed a high removal of MS2 (2.49 × 10¹¹ plaque forming unit/g) and RV (8.9 × 10⁶ focal forming unit/g) at a low concentration of hematite nanoparticles in solution (0.043 g/L and 0.26 g/L, respectively). Virus adsorption was, however, decreased in the presence of bicarbonate ions and natural organic matter (NOM) in solution, suggesting a great affinity of iron oxide nanoparticles for these competitors. Adsorption on hematite nanoparticles by MS2 and RV was also tested with aquifer groundwater under saturated flow conditions to mimic environmental conditions with promising results (8 × 10⁸ plaque forming unit/g and 3 × 10⁴ focal forming unit/g, respectively). Desorption of up to 63% of infectious MS2 and only 2% of infectious RV from hematite nanoparticles were achieved when an eluant solution containing beef extract and glycine was used. Transmission electron microscopy (TEM) images showed evidence of electrostatic adsorption of apparently intact MS2 and structurally damaged RV particles to hematite nanoparticles. Results from this research suggest that a cartridge made of glass fiber coated with hematite nanoparticles could be used as a point-of-use device for virus removal for drinking water treatment.     

The behaviour of masonry walls subjected to fire: Modelling and parametrical studies in the case of hollow burnt-clay bricks

A thermo-mechanical model is adopted in order to investigate the fire behaviour of clay masonry walls. In this analysis, conductive, convective and radiative thermal transfers are considered together with local energy consumption due to phase changes. These latter are essentially initiated by both the vaporisation of adsorbed water and the chemical transformation of clay under rising temperatures. Therefore, experimental tests at both the material scale and the brick scale are performed in order to identify the parameters that characterise the thermo-hygral behaviour of clay. For this purpose, numerical simulations are carried out on the experimentally tested hollow bricks in order to determine by back analysis these material parameters. The thermal model being validated, the thermo-mechanical behaviour of a masonry wall subjected to fire, is thereafter investigated by adopting a full three-dimensional finite-element analysis. Numerical simulations results are compared to the experimentally measured ones in terms of both temperature and out-of plane displacement fields. In this analysis, it is shown that a non-linear elastic behaviour for bricks and mortar with temperature-dependent mechanical parameters is sufficient to retrieve the overall behaviour of thin masonry walls. Finally, a parametric study provides the influence of each material parameter on the fire behaviour of the partition walls.