Synthesis and characterization of poly(arylene ether) containing cyanate ester networks

A series of bisphenols containing ether linkage were prepared from halo phenol/dihalo compound and dihydroxy compounds in the presence of K₂CO₃. The bisphenols were transformed to cyanate esters by treatment with cyanogen bromide using triethyl amine catalyst. The structure of all the five bisphenols and the cyanate esters were structurally confirmed by FT-IR, ¹H-NMR and ¹³C-NMR spectral methods and elemental analysis. The cyanate esters were cured at 100 °C (30 min) → 150 °C (30 min) → 200 °C (60 min) → 250 °C (3 hr). The thermal properties of the cured resins were studied by DSC and TGA. DSC analysis shows that these cyanate esters exhibit T _g in the range of 203–234 °C. The CE(c) has the highest glass transition temperature. The cyanate ester CE(e) shows the lowest T _g which is due to its asymmetric structure. The initial degradation temperature of the cured resins was found to be in the range of 324–336 °C. The Limiting Oxygen Index (LOI) value, determined by Van Krevelen’s equation, is in the range of 35.5–38.7.     

Synthesis,characterization, and thermal properties of cyanate esters with azo linkages

A series of azo functionalized diols were synthesized through diazotization which involves the reaction of amine with phenol and 2,6‐dimethyl phenol. Four different amines have been used to prepare five bisphenols. These bisphenols were converted to their corresponding cyanate esters by treatment with cyanogen bromide (BrCN) in the presence of triethylamine (Et₃N). The chemical structures of the prepared compounds were characterized with Fourier Transform Infrared, ¹H‐NMR, ¹³C‐NMR spectroscopy, and elemental analysis. Dynamic curing behavior was investigated using differential scanning calorimetry. The maximum curing temperature of these cyanate esters are in the range of (186–208°C). T_g values of the polycyanurate networks are in the range of 245–276°C. The thermal properties of cured cyanate ester were studied at a heating rate of 10°C min^?1 in N₂ atmosphere. The polymers showed excellent thermal stability (T₁₀ was found to be in the range 405–438°C) and the percentage of char yield at 800°C were found to be 30–49. The flame retardancy of the cyanate ester resins have been studied using limited oxygen index value which is in the range of 29.5–37.1 at 800°C. POLYM. ENG. SCI., 55:47–53, 2015. © 2014 Society of Plastics Engineers     

Raman,photoluminescence analysis on Cu(InAl)Se2 thin films and the fabrication of Cu(InAl)Se2 based thin film solar cells

Cu(InAl)Se₂ (CIAS) thin films have been prepared by chemical bath deposition technique. Thickness of the prepared films has been measured by gravimetric technique. The structure, composition and optical transition as well as bandgap have been estimated by X-ray diffraction, energy dispersive X-ray analysis and spectrophotometer analysis. Raman analysis has been made on the prepared CIAS thin films to assign the fundamental lattice mode and to confirm the films crystallinity and stoichiometry. PL analysis has been carried out to find the effective mass of holes and electron, dielectric constant, the involved defects and their activation energy. Cu(InAl)Se₂-based solar cells with different types of buffer layers such as CdS, CdS:Cu, CdS:In were fabricated. The current and voltage were measured using an optical power meter and an electrometer and the fabricated solar cells were illuminated using 100 mW/cm² white light under AM1 conditions.     

Real-time grasping strategies using event camera

Journal of Intelligent Manufacturing - Robotic vision plays a key role for perceiving the environment in grasping applications. However, the conventional framed-based robotic vision, suffering from...     

Texture pattern analysis of kidney tissues for disorder identification and classification using dominant Gabor wavelet

A study on ultrasound kidney images using proposed dominant Gabor wavelet is made for classifying a few important kidney categories. Three kidney categories, namely, normal (NR), medical renal diseases (MRD) and cortical cyst (CC) are considered for the analysis. Of the 30 Gabor wavelets, a unique dominant Gabor wavelet is determined by maximizing the similarity between original pre-processed image and reconstructed Gabor image. The dominant Gabor features “m_mn^D{\mu_{mn}^D } ” and “AAD_mn^D{AAD_{mn}^D } ” are then evaluated to characterize the tissues of kidney region and compared with the Gabor features derived by considering all Gabor wavelets individually and as a whole using the resultant classification efficiency. The results obtained show that the proposed dominant Gabor wavelet features provide the classification efficiency of 86.66% for NR, 76.66% for MRD and 83.33% for CC, while individual wavelet features offer less than 70%, 63.33% and 66% for NR, MRD and CC. The overall classification efficiency improves by 18.89% with dominant Gabor features when compared to the classification efficiency obtained by considering all the Gabor wavelets features. The outputs of the proposed technique are validated with medical experts to assess the actual efficiency. The overall discriminating ability of the systems is also evaluated with performance evaluation measures, F-score and ROC. It has been observed that the dominant Gabor wavelet improves the classification efficiency appreciably and explores the possibility of implementing a computer-aided diagnosis system exclusively for ultrasound kidney images.     

Preparation,characterization, and functional analysis of zinc oxide nanoparticle-coated cotton fabric for antibacterial efficacy

Nanotechnology is an emerging interdisciplinary technology and nanostructures capable of enhancing the physical properties of conventional textiles in areas such as antimicrobial properties, water repellence, soil resistance, antistatic, anti-infrared and flame-retardant properties, dye ability, color fastness, and strength of textile materials. The studies were carried out in order to fine tune the preparation of zinc oxide nanoparticles (NPs) for special applications. Soluble starch (stabilizing agent), zinc nitrate and sodium hydroxide (precursors) were used for the preparation of zinc oxide NPs by wet chemical method. The synthesized NPs were coated on cotton fabric (plain weave), and the antibacterial property of the treated fabric was analyzed. Fourier transform infrared spectroscopic analysis, scanning electron microscopy, and physical and chemical characterization were employed to determine the phase and morphology of the final nanoparticle-coated fabric. The results indicated that 2% zinc oxide nanoparticle (200 nm) -coated fabric have high antibacterial efficiency (99.9% against Staphylococcus aureus and 80% against Escherichia coli) and upon washing the coated fabric (five hand washes), the antibacterial activity was found to be 98% against S. aureus and 75% against Escherichia coli.     

Dual chemosensing properties of new ferrocene-based receptors towards fluoride and copper(II) ions

The new ferrocene based receptors N-[4-ferrocenyl-2-methyl-4-oxobut-1-enyl]-N′-phenylthiourea (1), N-[4-ferrocenyl-2-methyl-4-oxobut-1-enyl]-N′-[4-nitrophenyl]thiourea (2) were synthesized and characterized. Fluorescence titrations of receptors 1 and 2 with various transition metal ions showed selective response to Cu²⁺ ions and the emission intensities quenched significantly. Electrochemical titrations with anions revealed that receptors 1 and 2 sensed the F⁻ anion in high selectivity with a cathodic shift of 100 mV.