A spiral shaped regenerative microfluidic fuel cell with Ni‐C based porous electrodes

Microchannel geometry, electrode surface area, and better fuel utilization are important aspects of the performance of a microfluidic fuel cell (MFC). In this communication, a membraneless spiral‐shaped MFC fabricated with Ni as anode and C as a cathode supported over a porous filter paper substrate is presented. Vanadium oxychloride and dilute sulfuric acid solutions are used as fuel and electrolyte, respectively, in this fuel cell system. The device generates a maximum open‐circuit voltage of ~1.2 V, while the maximum energy density and current density generated from the fuel cell are ~10 mW cm^?2 and ~51 mA cm^?2, respectively. The cumulative energy density generated from the device after five cycles are measured as ~200 mW after regeneration of the fuel by applying external voltage. The spiral design of the fuel cell enables improved fuel utilization, rapid diffusive transport of ions, and in‐situ regeneration of the fuel. The present self‐standing spiral‐shaped MFC will eliminate the challenges associated with two inlet membrane‐less fuel cells and has the potential to scale up for commercial application in portable energy generation.     

View invariant DIBR-3D image watermarking using DT-CWT

In 3D image compression, depth image based rendering (DIBR) is one of the latest techniques where the center image (say the main view, is used to synthesise the left and the right view image) and the depth image are communicated to the receiver side. It has been observed in the literature that most of the existing 3D image watermarking schemes are not resilient to the view synthesis process used in the DIBR technique. In this paper, a 3D image watermarking scheme is proposed which is invariant to the DIBR view synthesis process. In this proposed scheme, 2D-dual-tree complex wavelet transform (2D-DT-CWT) coefficients of centre view are used for watermark embedding such that shift invariance and directional property of the DT-CWT can be exploited to make the scheme robust against view synthesis process. A comprehensive set of experiments has been carried out to justify the robustness of the proposed scheme over the related existing schemes with respect to the JPEG compression and synthesis view attack.

     

Insight into the Solid Electrolyte Interphase Formation in Bis(fluorosulfonyl)Imide Based Ionic Liquid Electrolytes

The formation of the solid electrolyte interphase (SEI) in an ionic liquid electrolyte of 0.5 m lithium bis(fluorosulfonyl)imide (LiFSI) in 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide at high cell voltages (1.7–1.9 V) is investigated in ordered mesoporous carbon (OMC) based Li metal cells using an operando small-angle neutron scattering (SANS) technique coupled with electrochemical impedance spectroscopy and ex situ X-ray photoelectron spectroscopy (XPS). It is demonstrated that discharging the OMC Li metal cells to ≈2 V and holding the cell voltage constant induces a rapid current increase with time, confirming extensive reduction and SEI formation. XPS analysis reveals that LiF is formed at open cell voltage (OCV), which is attributed to the carbenes generated at the lithium negative electrode because of its reaction with EMIm cation diffusing to and initiating the reaction with FSI⁻ anions at the carbon positive electrode. It is confirmed that the chemical reaction at OCV and electrochemical reduction at high cell voltage of the FSI⁻ anion plays a protective role against EMIm cation co-intercalation into the carbon positive electrode during the initial discharge. Operando SANS studies also suggest that slight differences occur in the surface composition and reaction mechanism as a function of cell voltage.     

Engineering the Interlayer Spacing by Pre-Intercalation for High Performance Supercapacitor MXene Electrodes in Room Temperature Ionic Liquid

MXenes exhibit excellent capacitance at high scan rates in sulfuric acid aqueous electrolytes, but the narrow potential window of aqueous electrolytes limits the energy density. Organic electrolytes and room-temperature ionic liquids (RTILs) can provide higher potential windows, leading to higher energy density. The large cation size of RTIL hinders its intercalation in-between the layers of MXene limiting the specific capacitance in comparison to aqueous electrolytes. In this work, different chain lengths alkylammonium (AA) cations are intercalated into Ti₃C₂T_x, producing variation of MXene interlayer spacings (d-spacing). AA-cation-intercalated Ti₃C₂T_x (AA-Ti₃C₂), exhibits higher specific capacitances, and cycling stabilities than pristine Ti₃C₂T_x in 1 m 1-ethly-3-methylimidazolium bis-(trifluoromethylsulfonyl)-imide (EMIMTFSI) in acetonitrile and neat EMIMTFSI RTIL electrolytes. Pre-intercalated MXene with an interlayer spacing of ≈2.2 nm, can deliver a large specific capacitance of 257 F g⁻¹ (1428 mF cm⁻² and 492 F cm⁻³) in neat EMIMTFSI electrolyte leading to high energy density. Quasi elastic neutron scattering and electrochemical impedance spectroscopy are used to study the dynamics of confined RTIL in pre-intercalated MXene. Molecular dynamics simulations suggest significant differences in the structures of RTIL ions and AA cations inside the Ti₃C₂T_x interlayer, providing insights into the differences in the observed electrochemical behavior.     

Modification of polyvinyl butyral rheological properties via blending with ionomeric polyvinyl butyral

Summary Polyvinyl butyral containing ionomer groups (IPVB) can be blended with conventional polyvinyl butyral (PVB) in order to modify rheological properties of the latter including ambient temperature stiffness and flow at processing temperatures. Thus by blending IPVB with PVB at levels up to 50 percent by weight, increases in the ambient temperature stiffness as measured by the storage modulus of the polymer blends (G) are achieved while maintaining or improving flow characteristics at processing temperatures.     

Striped nanowires and nanorods from mixed SAMS

We investigate the use of mixed self-assembled monolayers (SAMs) for creating nanoscale striped patterns on nanowires and nanorods. Our simulations predict that SAMs comprised of an equal composition of length-mismatched, thermodynamically incompatible surfactants adsorbed on nanowire surfaces self-organize into equilibrium stripes of alternating composition always perpendicular, rather than parallel, to the nanowire axis. We support the simulation results with preliminary experimental investigations of gold nanorods coated with binary mixtures of ligand molecules, which show stripes roughly perpendicular to the rod axis in all cases.     

Novelty of bamboo fabric

Fabric samples using 100% cotton, 100% viscose rayon, 100% regenerated bamboo viscose fibre and cotton/bamboo viscose blend (60/40) were produced and characterised for hand value and health care applications. The present study shows the results of these woven fabrics in terms of antibacterial, absorbency, ultraviolet protection factor (UPF), static characteristics, moisture vapour permeability (MVTR) and handle and dust catchability. Bamboo fabrics (100%) give better results compared to 100% cotton and 100% viscose fabric in terms of antibacterial property and absorbency i.e. wettability. Bamboo fabric (100%) also shows slightly higher moisture vapour transmission rate than cotton fabric. In the case of UPF, 100% cotton and 100% bamboo give excellent-rated UPF. There is no significant difference between these fabric samples in terms of time to lapse half saturated voltage. Total hand value is higher in the case of viscose and bamboo fabric than cotton fabric. The studies also show that breaking load and extension of bamboo gauze bandages are higher than cotton bandages. Sinking time is faster but absorptive capacity is lower in the case of bamboo gauze bandage than cotton gauze bandage.     

Steganalysis of Network Packet Length Based Data Hiding

Recently, data hiding by modifying network parameters like packet header, payload, and packet length has become popular among researchers. Different algorithms have been proposed during the last few years which have altered the network packets in different ways to embed the data bits. Some of these algorithms modify the network packet length for embedding. Although most of the packet length based embedding schemes try to imitate the normal network traffic distribution, they have altered the statistical distribution of network packet lengths during embedding. These statistical anomalies can be exploited to detect such schemes. In this paper, a second order detection scheme for packet length based steganography has been proposed. A comprehensive set of experiments have been carried out to show that the proposed detection scheme can detect network packet length based steganography with a considerably high accuracy.     

Heat transfer and flow pattern in co‐current downward steam condensation in vertical pipes‐II: Comparison with published work

The condensation of pure steam flowing downward inside a vertical tube has been extensively studied. Considerable amount of experimental and analytical efforts can be found due to the significance of this subject in practice. In this work, a critical review of the most important experimental, analytical and computational fluid dynamic (CFD) investigations have been presented. CFD simulations for the geometries of Goodykoontz and Dorsch [Goodykoontz and Dorsch, NASA TN D‐3326, 1966; Goodykoontz and Dorsch, NASA TN D‐3953, 1967], Kim and No [Kim and No, Int. J. Heat Mass Transf. 2000;43:4031–4042] and the present work have been performed and compared with the experimental data reported in these investigations. CFD predictions of the pressure drop and the heat transfer coefficient (HTC) were in close agreement with the experimental values. A preliminary regime map has been constructed for downward flow steam condensation inside pipes. Finally, all the published semi‐empirical correlations for the HTC have been critically analysed and compared with the CFD predictions. An attempt has been made to make specific recommendations. © 2012 Canadian Society for Chemical Engineering