Direct synthesis of nitrogen-rich carbon sheets via polybenzoxazine as highly active electrocatalyst for water splitting

In this work, we propose a novel nitrogen-rich carbon sheets (N-CSs), with conceivable use as efficient catalysts for hydrogen evolution reaction (HER). N-CSs are directly synthesized from polybenzoxazine (PBz) by carbonization followed by KOH activation. PBz was prepared from eugenol, melamine, and paraformaldehyde through ring-opening polymerization. FT-IR and NMR spectroscopy confirmed the corresponding chemical structures of the new benzoxazine monomer. The morphology, structure and surface properties of the N-CSs are investigated by Raman spectroscopy, wide-angle X-ray diffraction, and X-ray photoelectron spectroscopy. The catalytic activity of N-CSs towards HER is thoroughly investigated by electrochemical techniques. In N-CSs, it is established that nitrogen gratified electrocatalytic activity, and hence nitrogen atoms should enhance the electrocatalytic properties by increasing the active sites. As the kinetic current is stabilized by the outer nitrogen atom as such, HER is proposed to proceed on these active sites by the Volmer-Heyrovsky mechanism. The N-CSs show outstanding catalytic activity towards HER with lowest onset-potential (?10 mV_RHE) and Tafel slope (45 mV dec^?1) in 0.5 M H₂SO₄ aqueous electrolyte.     

Thermal and Structural Response of RCC Dams During Their Service Life

Roller compacted concrete (RCC) dams are vulnerable to cracking as a result of high tensile stresses due to material properties, thermal and mechanical loads. Making reliable prediction of stress fields, and thereby temperature cracking risk form an important part of the material modelling. The present study figures out the changes in thermal stresses and crack fields of the Kinta RCC dam at the end of the construction and its service life. Water temperature at various levels of the reservoir and its fluctuations were considered in the present study. The developed finite element program has been used in the analysis. Based on the obtained results, it is revealed that there is an increase in the thermal stresses after some years of dam completion. However, their location and distribution are mostly similar.     

Conducting polymer coated textile based multilayered shields for suppression of microwave radiations in 8.2–12.4 GHz range

Polypyrrole (PPY) based conducting textiles were prepared by in situ polymerization of pyrrole over cotton fabric. The SEM micrographs show smooth and uniform coating of PPY over fabric with only few loose dendrites. The elemental analysis and XRD patterns revealed the presence of iron whereas magnetization measurement shows ferromagnetic signature with well defined hysteresis loop and saturation magnetization (Ms) of 0.3 emu/g. The good antistatic property and rapid static charge dissipability was reflected by decay profile with decay time of only 0.16 sec. In addition, the microwave absorption studies of multilayered shields; made up of these conducting fabrics; show absorption dominated total shielding effectiveness (SE_T) value of ?43.9 dB (i.e. >99.99% attenuation) which can be attributed to the better impedance matching, high microwave conductivity, shallow skin depth, and multiple scattering of incident electromagnetic radiation. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effect of polyaniline concentration on the photoconversion efficiency of nano-TiO<Subscript>2</Subscript> based dye sensitized solar cells

Extensive research have been made in improving the dye sensitized solar cells (DSSC) performance by designing, tailoring and enhancing the photoconversion properties of the matrix. The approaches used are material synthesis, dye permutation combinations, use of natural extracts or using several sensitizers. The polymers are also being explored in this regards in their pristine or composite forms. Therefore, in this study an attempt is made to synthesize a mesoporous polyaniline–titanium dioxide (PANI–TiO₂) nanocomposites with one pot synthesis approach at different concentrations of PANI (0.3–0.7 ml). Titanium isopropoxide was used as precursor for TiO₂ with aniline and the material was synthesized at ice bath temperature. Morphological observations showed that the composite is a mesoporous material with tubular structure where TiO₂ particles are seen entrapped in the polymer matrix and found that intercalation can be tailored with PANI concentration. Structural, functional and optical characterization indicate anatase phase of TiO₂, with several functional bands that can help in dye interaction and broad absorption bands within visible region. The photocurrent-voltage response was measured with simulated light and source-meter. It is interesting to note that increasing PANI concentration enhances the mesoporous structure and hence increases the dye loading capacity and photoconductivity of the material. The efficiency increased by about 22 % with addition of 0.5 ml of PANI from 0.3 ml. The proposed study has indicated that such material have the potential to be used for DSSC fabrication with which the device performance can further be increased to a better levels.     

Thermophysical Properties of Binary Mixtures of Methanol with Chlorobenzene and Bromobenzene from 293 K to 313 K

Densities and viscosities have been measured for the binary mixtures of methanol with chlorobenzene and with bromobenzene from 293 K to 313 K over the complete composition range. Densities were used to compute the excess molar volume ( , for these binary systems. The results have been discussed in terms of molecular interactions. Furthermore, viscosity results were compared with a corresponding-states model. The average absolute deviation was found to be 1.9 %.     

Design of high performance copyright protection watermarking based on lifting wavelet transform and bi empirical mode decomposition

This paper developed new and efficient image watermarking scheme for copyright protection based on Lifting wavelet transform (LWT) and Bi- dimensional Empirical Mode Decomposition (BEMD). A LWT has been selected because it is fast, less computational cost and maintains the integrity of the recovered watermark. The BEMD transform can separate the image from the most robust to the least sensitive or fragile frequency bands. This advantage is utilised in this study for the purpose of embedding the watermark in the robust part of BEMD, i.e. the residue (r). In addition, the embedding process has been performed in the low sub-band of LWT decomposed image as the low sub-band is more robust to image processing such as JPEG compression. The robust watermark which is grey scale image is decomposed using DWT to enhance the security and select only high sub-band as it has less impact on the quality of the watermarked image. As a result, the original image’s visual quality can be preserved and the concealed watermark could be successfully retrieved even if the watermarked images have undergone severe attacks like JPEG, rotation, Gamma correction, filtering, additive noise, translation, shearing, and scaling. Furthermore, the improved scheme offers greater robustness against many image processing operations, in comparison to the current schemes about copyright protection.     

Spatial planning and climate change

Wind energy development is expanding. Preparations for wind farms include environmental impact assessments, specifically with visual impact assessments (VIAs). Often using simulated photographs, VIAs depict the post-development landscape appearance with new wind energy structures. This Ontario case study compares simulated photographs submitted as part of a VIA with post-development conditions. Simulations were judged for accuracy in turbine number, height, diameter, and location, and adequacy in representation of built conditions. Simulations were partially representative of postdevelopment conditions, yet commonly under-represented turbine number and size in different locations than they were built. Simulation frames were too narrow to adequately represent human vision and simulations under-estimated how many wind turbines were visible from a single landscape position. Outcomes suggest that visual simulations can lack accuracy or representativeness, misleading the public. Adopting province-wide VIA criteria and increasing adherence to visual simulation guidance may be necessary to improve the accuracy and representativeness of VIA content.     

Effect of size of fly ash particle on enhancement of mullite content and glass formation

Quartz is widely replaced by fly ash in traditional porcelain composite. Increased strength and stability of the fly ash-mixed composite depends on the quantity and crystallinity of the mullite phase in the fly ash. Our aim in this investigation is to increase the formation of mullite in nanocrystalline form and study the effect of temperature. Quantitative estimation of mullite and residual quartz content were done by X-ray diffraction (XRD) and nanostructure and crystallization were studied using differential thermal analysis (DTA), field effect scanning electron microscopy (FESEM), XRD and Fourier transform infrared (FTIR) spectroscopy. The results show that fly ash sieved through 250 holes/cm² mesh contain more mullite initially and growth of mullite as well as glass formation was faster in this sample compared to coarse fly ash. The maximum mullite in these samples was formed at 1600°C. Transformation of quartz and cristobalite phases into glassy phase was also faster for smaller particle sizes of fly ash.     

Antibodies to single-stranded and double-stranded DNA in antinuclear antibody-positive type 1-autoimmune hepatitis

To determine the significance of antibodies to single-stranded (anti-ssDNA) and double-stranded DNA (anti-dsDNA) in antinuclear antibody (ANA)-positive type 1 autoimmune hepatitis, sera from 53 patients were tested by enzyme immunosorbent assay (ELISA) and indirect immunofluorescence using the Crithidia luciliae substrate. Anti-dsDNA were detected in 18 patients (34%) by ELISA and 12 patients (23%) by the Crithidia-based assay. Twenty patients with anti-dsDNA by either assay (38%) had higher serum levels of immunoglobulin G (3971 +/- 270 mg/dL vs. 3201 +/- 247 mg/dL, P = .05) than seronegative patients. They also had human leukocyte antigen (HLA) DR4 more commonly than other patients (83% vs. 41%, P = .006) and normal subjects (83% vs. 30%, P = .00007). In contrast to patients seropositive by the Crithidia-based assay, those seropositive by ELISA failed corticosteroid therapy more commonly (24% vs. 3%, P = .04). Anti-ssDNA were found in 45 patients (85%) and they did not distinguish patients with different clinical features or outcomes. We conclude that anti-dsDNA are common in ANA-positive type 1 autoimmune hepatitis. HLA DR4 is associated with their production, and seropositivity by ELISA characterizes patients who have a poorer immediate response to corticosteroid treatment. Anti-ssDNA are common but they do not have important clinical implications.