MODIFICATIONS OF BITUMEN BY ELASTOMER AND REACTIVE POLYMER—A COMPARATIVE STUDY

With increasing demand for higher performance, different modifications to asphalt are being explored. Asphalt is expected to become harder on modification thereby improving its life span. The modification further helps asphalt in developing resistance to cracking/fatigue at low temperatures and stability with minimum creep at higher temperatures. Polymers and rubber are being blended with asphalt to obtain good low temperature as well as high temperature performance. Various factors such as polymer chemical nature, molecular weight and particle size play a crucial role in determining the effect of modified asphalt properties. The effect of these factors and physical/chemical interaction between the additive and asphalt has not yet been fully established due to limitations in appropriate evaluation methodologies. This paper attempts to evaluate the improvements in modification of asphalt due to the addition of an elastomer and a reactive polymer, relatively. The evaluation is made more reliable and valid by considering all the three key characteristics namely cohesion, adhesion and durability aspects of the asphalt as the basis to highlight the improvements in application benefits.     

Prediction of surface roughness in turning operations by computer vision using neural network trained by differential evolution algorithm

In recent years, the measurement of surface roughness of a workpiece plays a vital role since the roughness of a surface has a considerable influence on the product quality and the functional aspects. In this work, a differential evolution algorithm (DEA)-based artificial neural network (ANN) has been used for the prediction of surface roughness in turning operations. Cutting speed, feed rate, depth of cut, and average gray level of the surface image of workpiece, acquired by computer vision, were taken as the input parameters and surface roughness as the output parameter. The results obtained from the DEA-based ANN model were compared with the backpropagation (BP)-based ANN. It is found that the error percentage is very close, and it is also observed that the convergence speed for the DEA-based ANN is higher than the BP-based ANN.     

Cloning and functional expression of Citrobacter amalonaticus Y19 carbon monoxide dehydrogenase in Escherichia coli

Carbon monoxide (CO) is highly toxic but is an abundant carbon source that can be utilized for the production of hydrogen (H₂). CO-dependent H₂ production is catalyzed by a unique enzyme complex composed of carbon monoxide dehydrogenase (CODH) and CO-dependent hydrogenase (CO–H₂ase), both of which contain metal cluster(s). In this study, CODH and the required maturation proteins from the novel facultative anaerobic bacterium Citrobacter amalonaticus Y19 were cloned and heterologously expressed in Escherichia coli. For functional expression of CODH in E. coli, only CooF (ferredoxin-like protein) and CooS (CODH), not the maturation proteins, were needed. The recombinant E. coli BL21(DE3)-cooFS showed a 3.5-fold higher specific CODH activity (4.9 U mg protein⁻¹) compared to C. amalonaticus Y19 (Y19) (1.4 U mg protein⁻¹). Purified heterologous CODH from the soluble cell-free extract of the recombinant E. coli showed a specific activity of 170.6 U mg protein⁻¹. Recombinant E. coli harboring Y19 CODH and maturation proteins did not produce H₂ from CO, suggesting that the native hydrogenases present in E. coli could not substitute the Y19 CO–H₂ase for CO-dependent H₂ production.     

Role of newspapers in creating mass concern with environmental issues in India

The present study has been undertaken with the objective of assessing the role of Indian newspapers in creating mass concern with environmental issues. The content analysis of three leading national English dailies revealed that these newspapers publish news items, editorials and articles on environmental issues of local, national and international interest. They brought into focus specific environmental problems in sufficient intensity with scope and time. A survey was conducted to obtain opinions of individuals about the extent of role of Indian newspapers in arousing popular interest by way of disseminating information about the environmental problems. The response strongly suggests a limited role of the Indian press in creating mass concern with environmental issues. Various reasons for the unsuccessful performance of the press have been presented. Two mass media‐public interaction models are also discussed in light of their value for the environmental problems of India.     

Quantitative method for analysis of monensin in soil, water, and urine by direct combination of single-drop microextraction with atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry

A simple and selective analytical method for the quantitative determination of low concentrations of monensin in soil, surface water, and human urine has been developed. Prior to atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry (AP-MALDI-MS) analysis, the samples were preconcentrated by using the single-drop microextraction (SDME) technique. Several factors that affect the analyte's extraction, including selection of solvent, microdrop volume, extraction time, and ionic strength, were investigated. Chloroform-toluene (1:1, v/v) was selected as the extraction solvent. Reliable results were obtained using dibenzo-30-crown-10-ether as an internal standard. The proposed method has been successfully applied for the determination of monensin in soil, surface water, and human urine spiked samples. Under the optimized conditions, the limits of quantification of the analyte in surface water, soil, and human urine were 6.7, 12.4 and 7.8 ng/mL, respectively. The intraday and interday precision variation and accuracy of the present method is within the acceptable ranges. The present method avoids the pre- and postderivatization of weak UV absorbing monensin determination using high performance liquid chromatography-ultraviolet detection (HPLC-UV). Furthermore, these techniques are time-consuming, nonreproducible at trace levels, and form undesirable products. The proposed SDME combined with AP-MALDI-MS is simple, fast, and selective for the determination of monensin in environmental and urine samples.     

Effect of Molecular Rotation on Vapor Phase Nucleation: Fullerenes C60 and C70

Abstract

The effect of rotational free energy of fullerenes C₆₀ and C₇₀ on homogeneous nucleation of crystals from vapor phase have been studied. Classical nucleation parameters have been estimated for the case of nucleation and crystal growth of C₆₀ and C₇₀ by Physical Vapor Transport (PVT) method under different supercooling in the range of 20–150 K, keeping the source temperatures constant. The result shows that the growth of large size single crystals is more feasible in the lower supercooling range. The effect of change in interfacial tension on the critical free energy of formation of the nuclei is also studied.     

Dispersant-free disperse dyes for polyester an eco-friendly approach

Disperse dyes contain around 30–60% of dispersing agents as well as dyeing with disperse dyes requires around 2–5 g/L of dispersing agent for faultless dyeing of polyester and other hydrophobic fibres. Dispersing agents are not absorbed by the fibres and a large quantity of dispersing agent creates unavoidable load on the effluent treatment. Dispersant-free disperse dyes seem to have an acceptable solution to this existing problem. These dyes can work in absence of dispersing agents and thus are called as dispersant free disperse dyes. In this work, dispersant-free disperse dyes were synthesised by coupling diazotised p-nitroaniline with the different components like sulfomethylated aniline and m-toluidine. These synthesised dyes were applied successfully on polyester which resulted into uniform dyeing, good build-up and desired colour yield. The dyeing was dependent on the pH and the optimum pH was 5 similar to that employed in conventional polyester dyeing. The fastness properties obtained were good and comparable with the conventional dyes. Whereas the chemical oxygen demand levels of the dispersant-free disperse dyes were much lower than those from commercial disperse dye.     

Linear quadratic regulators with eigenvalue placement in a specified region

A linear optimal quadratic regulator is developed for optimally placing the closed-loop poles of multivariable continuous-time systems within the common region of an open sector, bounded by lines inclined at ±π/2k (k = 2 or 3) from the negative real axis with a sector angle ≤π/2, and the left-hand side of a line parallel to the imaginary axis in the complex s-plane. Also, a shifted sector method is presented to optimally place the closed-loop poles of a system in any general sector having a sector angle between π/2 and π. The optimal pole placement is achieved without explicitly utilizing the eigenvalues of the open-loop system. The design method is mainly based on the solution of a linear matrix Lyapunov equation and the resultant closed-loop system with its eigenvalues in the desired region is optimal with respect to a quadratic performance index.     

Thermally stimulated discharge current studies on PMMA-PVAc blends

Thermally stimulated discharge current (TSDC) studies have been carried out on blends of polymethyl methacrylate (PMMA) and polyvinyl acetate (PVA). The effects of polarization temperature and field on the TSDC peaks of polyblends indicate that the polarization in the polyblends is due to charge-carrier trapping in deep traps which leads to induced dipole formation. The results of a.c. dielectric bridge measurements are also compared with the TSDC results. The dielectric relaxation parameters are also reported.