Effect of heat-treatment temperature on carbon corrosion in polymer electrolyte membrane fuel cells

This study examines the effect of heat-treatment temperature on the electrochemical corrosion of carbon nanofibers (CNFs) in polymer electrolyte membrane (PEM) fuel cells. Corrosion is investigated by monitoring the generation of CO₂ using an on-line mass spectrometer at a constant potential of 1.4 V for 30 min. The experimental results show that the generation of CO₂ decreases with increasing heat-treatment temperature, indicating that less electrochemical carbon corrosion occurs. In particular, when the heat-treatment temperature is 2400 °C, the change intensifies. X-ray photoelectron spectroscopic analysis shows that oxygen functional groups on the carbon surface decrease with increasing heat-treatment temperature. A reduction in oxygen functional groups increases the hydrophobic nature of the carbon surface, which is responsible for the increased corrosion resistance of CNFs.     

Exergo‐economic analysis of micro pin fin heat sinks

A parametric study of thermoeconomic performance over four micro pin fin heat sinks of different spacing and shapes was conducted. Unit cost per product exergy, relative cost difference, and exergo‐economic factor were utilized to evaluate the thermoeconomic performance. The effect of working fluid on the thermoeconomic performance was also investigated using R‐123 and water as working fluids. Unit costs per product exergy were obtained to evaluate the product costs (total exergy change between exit and inlet streams) in micro pin fin heat sinks at fixed mass flow rate and fixed pressure drop. The results of the thermoeconomic analysis were compared with the results of a past exergy performance study by the author. In the light of raw experimental data acquired from the past studies of the author, important differences between the results of exergy and exergo‐economic performances were observed. It was found that the unit cost of exergy change decreased as electrical power increased and the relative cost difference approached to unity at high electrical powers (greater than 20 W). Moreover, high exergo‐economic factor values (more than 0.5) were obtained at low electrical powers while exergo‐economic factors had a small value at high electrical powers. When looking at the effect of the working fluid, higher cost per Watts of the products (up to the double of R‐123) was obtained with water compared with R‐123 at both fixed mass flow rate and pressure drop. No significant effect of pin fin spacing on the unit cost of exergy change was observed at fixed mass flow rate, while higher unit costs (up to 102%) were recorded at fixed pressure drop for scarcely packed pin fin heat sinks. Finally, the unit cost of exergy change was found to be independent of pin fin shape at fixed mass flow rate, whereas at fixed pressure drop, the hydrofoil‐based pin fin heat sink had higher unit costs (up to 1.8 times as much) when compared with the unit costs of pin fin heat sinks having flow separation promoting pin fins. Copyright © 2010 John Wiley & Sons, Ltd.     

Developing a custom DSP for vision based human computer interaction applications

Multimedia Tools and Applications - As the computing power of modern devices become greater, computer vision is increasingly adopted as the means of human-computer interaction. The industry is...     

DADE: a fast data anomaly detection engine for kernel integrity monitoring

The Journal of Supercomputing - In computer systems, ensuring the integrity of the kernel assumes importance as attacks against the kernel allow an adversary to obtain the highest privilege within...     

Design,synthesis, and characterization of hybrid micro-nano surface coatings for enhanced heat transfer applications

Metal particles coating is extensively used for surface coating a wide range of application including thermal management of electronics, concentrating photovoltaics, sensors and nuclear power plants. Both micro and nano-scale surfaces have been proven to show an enhanced two-phase heat transfer performance by varying surface properties like area, wettability, and roughness. To combine the unique features of both micro and nano-scale surface coatings, this study presents the design, synthesis, and characterization of new hybrid micro-nano scale surface coating by a new two steps approach. Five different types of surfaces; namely, plain nanocoated (PNC), uniform micro-porous (UMP), uniform hybrid micro-nano porous (UHMNP), 2-D modulated microporous (MMP) and modulated hybrid micro-nano (MHMNP) surfaces were fabricated. A new two steps approach of hot-pressing followed by nucleate boiling is used for the fabrication of these surfaces. Successful coating of hybrid micro-nano scale coating was achieved. Considering the critical surface properties of micro and nanoscale coatings, new hybrid micro-nano surfaces have been characterized for SEM, wettability, roughness test. The comparative analysis of these new hybrid coating is also performed with micro coated and uncoated surfaces. With the coating of nanoparticles, the average roughness of PNC surface increased by 4.67 times and that of hybrid micro-nano particle surface by 2.3 times. The deposition of nanoparticles resulted in an increase in contact angle for PNC surface, while the contact angle of hybrid micro-nano surfaces decreases from 126.4° to 82.1°.     

A Polyallylamine Anchored Amine‐Rich Laser‐Ablated Graphene Platform for Facile and Highly Selective Electrochemical IgG Biomarker Detection

Current immunosensors have an insufficient number of binding sites for the recognition of biomolecules, which leads to false positive or negative results. In this research, a facile, cost‐effective, disposable, and highly selective electrochemical immunosensing platform is developed based on cationic polyelectrolyte polyallylamine (PAAMI) anchored laser‐ablated graphene (LAG). Here, for the first time, PAAMI is introduced to stabilize LAG flakes, while retaining the intrinsic thermal and electronic properties of the substrate by noncovalent π–π interaction and electrostatic physical absorption. The sensing platform offers a suitable number of anchoring sites for the immobilized antibodies by providing ? NH₂ functional groups. The proper grafting of PAAMI is confirmed through X‐ray photoelectron spectroscopy and Raman spectroscopy. The immunosensing platform is applied to detect immunoglobulin (IgG) biomarkers as a proof of concept. Under optimized conditions, the sensing platform exhibits a linear range of 0.012–15 and 15–352 ng mL^?1 with a limit of detection of 6 pg mL^?1 for IgG detection with high selectivity. Based on the analysis, the developed immunosensing platform can be used for point‐of‐care detection of IgG in clinical diagnostic centers. Furthermore, the developed strategy is well suited for the detection of other cancer biomarkers after immobilizing the relevant antibodies.     

Automatic Transformation of Membrane‐Type Electronic Devices into Complex 3D Structures via Extrusion Shear Printing and Thermal Relaxation of Acrylonitrile–Butadiene–Styrene Frameworks

This work demonstrates a means of automatic transformation from planar electronic devices to desirable 3D forms. The method uses a spatially designed thermoplastic framework created via extrusion shear printing of acrylonitrile–butadiene–styrene (ABS) on a stress‐free ABS film, which can be laminated to a membrane‐type electronic device layer. Thermal annealing above the glass transition temperature allows stress relaxation in the printed polymer chains, resulting in an overall shape transformation of the framework. In addition, the significant reduction in the Young's modulus and the ability of the polymer chains to reflow in the rubbery state release the stress concentration in the electronic device layer, which can be positioned outside the neutral mechanical plane. Electrical analyses and mechanical simulations of a membrane‐type Au electrode and indium gallium zinc oxide transistor arrays before and after transformation confirm the versatility of this method for developing 3D electronic devices based on planar forms.