Studies on sintering kinetics and correlation with the sinterability of 8Y zirconia ceramics based on the dilatometric shrinkage curves

Prediction of the dominant sintering mechanism and corresponding temperature regimes become important in arriving at the optimum sintering schedule of ceramics. The sintering kinetics of 8Y zirconia (8YSZ) submicron powders, with particle sizes ～205 nm, has been evaluated through, (i) constant rates of heating and (ii) master sintering curve (MSC) technique. Slip cast green 8YSZ compacts, close to 50% of the theoretical density, have been subjected to dilatometry, for recording the shrinkage behavior, at constant heating rates of 5, 10 and 20 °C/min. The kinetics of the corresponding sintering process has been evaluated by estimating and comparing the apparent activation energies (Q) from the constant heating rate technique, and MSC approach. The observed apparent activation energy (～350 kJ/mol) suggests grain-boundary diffusion to be the dominant mechanism in sintering of 8YSZ ceramics.     

Synthesis,characterization, and magneto‐electric properties of (1−x)BCZT‐xCFO ceramic particulate composites

Synthesis of a new magnetoelectric [(1?x)(Ba_0.85Ca_0.15)(Zr_0.1Ti_0.9)O₃‐xCoFe₂O₄] (weight fraction x=0, 0.1, 0.2, 0.3, 0.4, 0.5 and 1) ceramic particulate composites with its structural characterization and magneto‐electric properties have been reported here in this study. Lead free piezoelectric (Ba_0.85Ca_0.15)(Zr_0.1Ti_0.9)O₃ (BCZT) and ferrimagnetic CoFe₂O₄ (CFO) were synthesized using sol‐gel and combustion methods respectively. (1?x)BCZT‐xCFO magnetoelectric composites were then synthesized by mixing of the calcined individual ferroic phases with required weight fractions. Powder X‐ray diffraction studies indicate the coexistence of BCZT and CFO phases in the composites sintered at 1300°C. 0.5BCZT‐0.5CFO composite showed high strain sensitivity (dλ/dH) of 52×10^?9 Oe^?1, which is comparable to that of pure CFO (50×10^?9 Oe^?1). A high piezoelectric voltage constant (g₃₃) of 8×10^?3 V m/N was measured for 0.8BCZT‐0.2CFO sample. All the composites showed magnetoelectric effect and a high magnetoelectric coupling coefficient (α_ME) of 6.85 mV/cm Oe was measured for 0.5BCZT‐0.5CFO composite at 1 kHz and a large ME coefficient of 115 mV/cm Oe at its resonance frequency. The effect of microstructure on the magnetoelectric properties of [(1?x)BCZT‐(x)CFO] composites has been studied and reported here as a function of its piezoelectric (BCZT)/ferrite (CoFe₂O₄) content.     

Investigation of solid supported dendrimers for water disinfection

Polystyrene copolymer beads supported dendrimer was synthesized and investigated for its biological applications. Macroporous cross‐linked polystyrene copolymer beads were synthesized using suspension polymerization. Two successive generations of di(chloroethyl) amine‐type end group functionality was formed on the polystyrene copolymer beads. Elemental analysis, Fourier transform infrared spectra, and solid state ¹³C NMR spectra were employed to characterize the polymer bound dendrimer. The polymer bound dendrimer was tested for antibacterial action against both Gram‐positive and Gram‐negative bacteria. The activity against both types of organism increased with an increase in the nitrogen atoms in the polymer back bone. The dendritic structure containing both amino and di(chloroethyl) groups showed significant reduction in the bacterial count when kept in 20 mL autoclaved water with bacterial cultures having an initial count in the range of 12–83 × 10⁶ CFU/mL. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Riemannian formulation and comparison of color difference formulas

Study of various color difference formulas by the Riemannian approach is useful. By this approach, it is possible to evaluate the performance of various color difference formulas having different color spaces for measuring visual color difference. In this article, the authors present mathematical formulations of CIELAB (ΔE), CIELUV (ΔE), OSA‐UCS (ΔE_E) and infinitesimal approximation of CIEDE2000 (ΔE₀₀) as Riemannian metric tensors in a color space. It is shown how such metrics are transformed in other color spaces by means of Jacobian matrices. The coefficients of such metrics give equi‐distance ellipsoids in three dimensions and ellipses in two dimensions. A method is also proposed for comparing the similarity between a pair of ellipses. The technique works by calculating the ratio of the area of intersection and the area of union of a pair of ellipses. The performance of these four color difference formulas is evaluated by comparing computed ellipses with experimentally observed ellipses in the xy chromaticity diagram. The result shows that there is no significant difference between the Riemannized ΔE₀₀ and the ΔE_E at small color difference, but they are both notably better than ΔE and ΔE. © 2011 Wiley Periodicals, Inc. Col Res Appl, 2011;     

Biocompatible,stimuli‐responsive hydrogel of chemically crosslinked β‐cyclodextrin as amoxicillin carrier

A novel pH‐responsive, chemically crosslinked hydrogelator (cl‐β‐CD/pVP) has been fabricated using β‐cyclodextrin (β‐CD) and N‐vinyl pyrollidone (N‐VP) in presence of diurethane dimethacrylate (DUDMA) crosslinker/azobisisobutyronitrile initiator through free radical polymerization. Various grades of cl‐β‐CD/pVP have been synthesized and the best grade has been considered with higher crosslinking density, higher gel strength, and lower % swelling ratio. The hydrogelator has been characterized by FTIR, ¹H and ¹³C NMR spectroscopy, TGA, and FESEM analyses. The hydrogelator demonstrates pH‐responsive behavior, which has been confirmed by swelling behavior and gel characteristics at various pH (at 37 °C). Using hen egg lysozyme, degradation experiment has been performed, which confirms the biodegradable nature of the hydrogel. The in vitro cytotoxicity study and live–dead assay suggest that the hydrogelator is cytocompatible toward MG‐63 cells. Finally, the hydrogelator shows excellent efficacy as an antibiotic (amoxicillin) carrier. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45939.     

Physical aging of polycarbonate block copolymers: Ductility rejuvenation below the glass transition temperature

Thermal aging of block copolymers of bisphenol A polycarbonate and polydimethylsiloxane (BPAPC and PDMS) have been studied. Changes in notched izod impact performance and yield stress are reported following aging at 120°C and 130°C for up to 20 days. Retention of impact at 120°C of the block copolymers was found to improve with increasing size of siloxane domains in the polycarbonate matrix. Quite contrary to our expectation, the retention of impact for a given sample at 130°C was found to be better than that of at120°C. These block copolymers showed (thermo) reversible ductility rejuvenation behavior at 130°C when the samples heat‐aged at 120°C were shifted from 120 to 130°C. Transmission electron microscopy, small‐angle X‐ray scattering, and dynamic mechanical analysis techniques were used to probe the observed phenomenon. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

Synthesis of a new rhodamine‐containing block copolymer for highly selective and sensitive detection of Cu2+ and CN− ions in aqueous media

Development of new chemosensors that are selective and sensitive to Cu²⁺ and CN^? ions, especially in aqueous media, is of tremendous importance. We report the synthesis of a new block copolymer that is capable of highly selective and sensitive detection of Cu²⁺ and CN^? ions in aqueous media. Poly(t‐butylacrylate)‐block‐poly(3‐bromopropylacrylate) was prepared using the reversible addition–fragmentation chain transfer polymerization technique. This block copolymer was reacted with 2,4‐dihydroxybenzaldehyde followed by reaction with rhodamine B hydrazide for successful incorporation of the desired rhodamine units into the block copolymer structure. Cu²⁺‐induced opening of the spirolactam ring of the rhodamine units resulted in rapid and easily noticeable colour change, thus enabling a highly selective detection of Cu²⁺ ions in aqueous media for concentrations as low as 2 µmol L^?1. We further demonstrate that this Cu²⁺ bound polymer complex can further act as a selective and sensitive sensing platform for CN^? in aqueous media with concentrations <1 µmol L^?1 (0.06 ppm). Moreover, the polymer can also be used to remove Cu²⁺ from aqueous media. © 2014 Society of Chemical Industry     

A novel method for binarization of scene text images and its application in text identification

Pattern Analysis and Applications - The aim of this article is twofold. First, we propose an effective methodology for binarization of scene images. For our present study, we use the publicly...     

Image encryption using permutation generated by modified Regula-Falsi method

Applied Intelligence - Transmission and sharing of multimedia data have drastically increased in the last few years due to the availability of low-cost image capturing devices, development of...     

Color image compression based on block truncation coding using pattern fitting principle

This paper describes a color image compression technique based on block truncation coding using pattern fitting (BTC-PF). High degree of correlation between the RGB planes of a color image is reduced by transforming them to O₁O₂O₃ planes. Each O_i plane (1?i?3) is then encoded using BTC-PF method. Size of the pattern book and the block size are selected based on the information content of the corresponding plane. The result of the proposed method is compared with that of several BTC based methods and the former is found superior. Though this method is a spatial domain technique, it is also compared with JPEG compression method, which is one of most popular frequency domain techniques. It is found that the performance of the proposed method is a little inferior to that of the JPEG in terms of quality of the reconstructed image. Decoding time is another important criterion where the compressed image is decoded frequently for various purposes. As the proposed method requires negligible decoding time compared to JPEG, the former is preferred over the latter in those cases.