Synthesis and Characterization of Conducting Composites of Polypyrrole/Polypyrrole-Coated Short Nylon Fiber and Natural Rubber

Pyrrole was polymerized in the presence of anhydrous ferric chloride as oxidant and p-toluene sulphonic acid as dopant. Polypyrrole-coated short Nylon fibers were prepared by polymerizing pyrrole in the presence of short Nylon fibers. The resultant polypyrrole (PPy) and polypyrrole-coated Nylon fiber (F-PPy) were characterized using SEM and then used to prepare rubber composites based on natural rubber. The cure pattern, cure kinetics, filler dispersion, DC conductivity, mechanical properties and morphology of the resulting composites were studied. The presence of PPy-coated fibers in the natural rubber/PPy system reduced the cure time significantly. The DC conductivity of the composites was found to be better for the F-PPy system compared to PPy-filled NR composite. The F-PPy system also showed better tensile strength, modulus and tear resistance.     

Study on properties of simul wood (Bombax ceiba L.) impregnated with styrene acrylonitrile copolymer, TiO2, and nanoclay

Dimensional stability, thermal, and water repellency are very important properties of wood. In this research, wood polymer nanocomposite (WPNC) has been prepared by impregnation of styrene acrylonitrile copolymer (SAN), ??-trimethoxy silyl propyl methacrylate-modified TiO₂ nanoparticles, nanoclay into simul (Bombex ceiba L.) wood. The characterization of the composites was done by using Fourier transform infrared spectroscopy, X-ray diffractometry, and thermogravimetry. The resultant WPNC exhibited an improvement in water repellency, moisture resistance, dimensional stability, chemical resistance, hardness, and thermal stability. The maximum improvement in all the properties has been observed for the wood sample treated with SAN/TiO₂ (0.5?%)/nanoclay (0.5?%).     

Bubble size and radial gas hold‐up distributions in a slurry bubble column using ultrafast electron beam X‐ray tomography

Gas hold‐up and bubble size distribution in a slurry bubble column (SBC) were measured using the advanced noninvasive ultrafast electron beam X‐ray tomography technique. Experiments have been performed in a cylindrical column (D_T = 0.07 m) with air and water as the gas and liquid phase and spherical glass particles (d_P = 100 μm) as solids. The effects of solid concentration (0 ≤ C_s ≤ 0.36) and superficial gas velocity (0.02 ≤ U_G ≤ 0.05 m/s) on the flow structure, radial gas hold‐up profile and approximate bubble size distribution at different column heights in a SBC were studied. Bubble coalescence regime was observed with addition of solid particles; however, at higher solid concentrations, larger bubble slugs were found to break‐up. The approximate bubble size distribution and radial gas hold‐up was found to be dependent on U_G and C_s. The average bubble diameter calculated from the approximate bubble size distribution was increasing with increase of U_G. The average gas hold‐up was calculated as a function of U_G and agrees satisfactorily with previously published findings. The average gas hold‐up was also predicted as a function of C_s and agrees well for low C_s and disagrees for high C_s with findings of previous literature. © 2012 American Institute of Chemical Engineers AIChE J, 59: 1709–1722, 2013     

Bioprocess for Hyperactive Thermotolerant Aspergillus fumigatus Phytase and its Application in Dephytinization of Wheat Flour

Catalysis Letters - In the present study, statistically optimized production of thermotolerant Aspergillus fumigatus phytase was carried out in batch fermentation (1-L). An enhancement in phytase...     

Damage accumulation in plasma-sprayed zirconia under cyclic loading

The stiffness and hysteretic response due to mechanical and thermo-mechanical cycling have been studied in plasma-sprayed yttria-stabilized zirconia (YSZ). Mechanical cycling of free-standing cantilevers of YSZ shows that the progressive decrease in stiffness is accompanied by monotonic increase in hysteretic energy dissipation per cycle and a permanent ratcheting displacement of ∼20 nm/cycle. Below a critical stress, it varies from coating to coating, ratcheting accompanied by a slow decrease in stiffness does not lead to failure even after ∼1000 cycles. In contrast, at higher stresses, the rates of ratcheting and decrease in stiffness increase rapidly, leading to the nucleation of macrocracks that lead to fracture failure. Prior thermal cycling of coatings on Inconel substrate up to 700°C, which induced an estimated cyclic thermal stress of ∼35 MPa, led to a pronounced reduction in stiffness and mechanical cycling life. During bending, damage accumulates in the tension side of the cantilever and the volume going through the compression cycle remains relatively undamaged.     

One step synthesis and characterization of copper doped sulfated titania and its enhanced photocatalytic activity in visible light by degradation of methyl orange

This paper reports on the synthesis of copper doped sulfated titania nano-crystalline powders with varying(2.0%–10.0%, by mass) by single step sol gel method. The synthesized photo catalyst has been characterized by employing various techniques like X-ray Diffraction(XRD), Ultraviolet–Visible Diffuse Reflection Spectroscopy(UV–Vis DRS), X-ray Photoelectron Spectroscopy(XPS), Scanning Electron Microscopy(SEM), Energy Dispersive Spectrometry(EDS), Fourier Transform Infrared Spectroscopic Studies(FT-IR), and Transmission Electron Microscopy(TEM). From the XRD and TEM results, all the samples were reported in anatase phase with reduction in particle size in the range of 7 to 12 nm. SEM indicated the change in morphology of the particles. The presence of copper in titania lattice was evidenced by XPS. From UV–Vis DRS and FT-IR studies indicated that prominent absorption shift is observed towards visible region(red shift), the entry of Cu2+into Ti O2 lattice as a substitutional dopant and SO42-ions were covalently bonded with Ti4 +on the surface of the copper doped titania respectively.The photocatalytic activity studies were investigated by considering methyl orange(MO) as dye pollutant in the presence of the visible light. The effect of various parameters like effect of dosage of the catalyst, dopant concentration, p H of the solution, and concentration of the dye was studied in detail.     

Kinetics and mechanism of styrene‐acrylonitrile copolymerization in micro‐emulsion

Stable and transparent poly(styrene‐acrylonitrile) latexes were produced by the polymerization of styrene‐acrylonitrile in ternary o/w micro‐emulsions containing sodium dodecyl sulfate as an anionic surfactant. Kinetics of copolymerization was studied at different temperatures using different concentrations of potassium persulfate and hydrogen peroxide/ascorbic acid. The suitability of existing model for homopolymerization was examined for styrene‐acrylonitrile copolymerization after appropriate modification. The latexes were characterized for particle size and number of particles by dynamic light scattering and TEM. The isolated products were characterized by ¹H and ¹³C NMR as well as by thermal analysis. The overall size of particles was found to be between 15 and 20 nm. © 2000 Society of Chemical Industry     

Using statistical data for reliable mobile communications

We examine the extent to which statistical mobility information can increase the reliability of the service experienced by users in mobile networks. Interrupted or dropped calls are an aspect of reliability that stems from the mobility of users. An existing user can move to a cell where there are no resources available to support their call. A natural solution is the reservation of resources in multiple cells that the user is likely to move to. This scheme is called selective reservations and it relies on predicting the next move of the user. Recently, there has been some work on estimating the movement probabilities (also known as the mobility profile) of the user. In this paper, we quantify the usefulness of the mobility profile to improve the reliability of the service perceived by the mobile users. We identify two parameters which characterize the profile: Accuracy and Focus. Accuracy expresses the probability that the host will move as we expect it to. Focus describes how well we can identify patterns in the movement of the users. In our simulations, we examine the effect of the quality of the predictions on the performance of the system. We show that Accuracy and Focus have great impact on the performance of selective reservations. We also show how flexibility in hand‐offs can help in decreasing the dropping probability, and how this can be facilitated by letting the users make a second try at moving in case it fails the first time. Copyright © 2001 John Wiley & Sons, Ltd.