Plasticizing effect of biodegradable dipropylene glycol bibenzoate and epoxidized linseed oil on diglycidyl ether of bisphenol A based epoxy resin

Major limitation for use of epoxy thermosets in engineering applications is its sudden brittle failure. In the present study dipropylene glycol dibenzoate (DPGDB) based plasticizer is used to modify diglycidyl ether of bisphenol A (DEGEBA) based epoxy resin system via simple blending technique. Bio-based epoxidized linseed oil was also used to modify epoxy resin system and compared with DPGDB modified resin. For DPGDB modified resin storage modulus and loss modulus of the epoxy system modified with 10% plasticizer increased by 7.54% and 12.24%, respectively. The primary mechanism responsible for such behavior is improved crosslinking density. With 5% plasticizer loading, flexural strength increased by 21%. There was an improvement of 312.74% in strain at failure for 10% plasticizer loading, while preserving its mechanical strength. It was found that DPGDB based modification was better than epoxidized linseed oil modification.     

Enhanced bioremediation of crude oil‐contaminated soil by a Pseudomonas species and mutually associated adapted Azotobacter vinelandii

A mixed culture of compatible hydrocarbonoclastic and diazotrophic bacteria, each at a density of 10⁸ organisms cm^?3, was developed for optimised bioremediation of crude oil‐contaminated soil. The hydrocarbonoclastic bacterium, Pseudomonas sp and the diazotroph, Azotobacter vinelandii, were both isolated from a previously crude oil‐contaminated soil and thereafter modelled as a unit of mutualistic consortium in situ. Stabilisation of the consortium and hence the optimised bioremediation process occurred when the bacterial growth attained a pseudo‐steady state condition. This was considered to be as a result of a symbiotic association between A vinelandii and the Pseudomonas sp in which A vinelandii produced the required concentration of fixed nitrogen compounds required for the growth of the Pseudomonas sp. Enhancement in biodegradation, due to stimulated growth of Pseudomonas sp and co‐metabolic activity of A vinelandii, was mathematically evaluated as the difference in the specific growth rates (µ) between the consortium Pseudomonas sp/A vinelandii and Pseudomonas sp alone. The proportion of petroleum hydrocarbons degraded by the consortium from the contaminated soil ranged between 66.83 and 69.6% as compared with that of a pure culture of Pseudomonas sp (23.2–44.45%). Hence, beyond their role in biological nitrogen fixation, diazotrophs may be used to contribute to bioremediation of crude oil‐contaminated land. Copyright © 2004 Society of Chemical Industry     

Application of an equation-oriented framework to formulate and estimate parameters of chemical looping reaction models

Accurate, predictive reaction models are critical for the design and optimization of chemical looping combustion (CLC) reactors. The formulation and estimation of kinetic parameters for these reaction models using a first-principles equation-oriented (EO) approach is particularly beneficial as large amounts of experimental data spanning process-relevant conditions can be used to estimate parameters in a computationally tractable way. This work demonstrates the application of a novel EO framework to develop reduction reaction kinetic models of an iron-based CLC oxygen carrier (OC). An optimization problem is formulated to estimate kinetic parameters that provide the best fit to the experimental data. The model predicts the state of the OC with mean square error values of 2.5%–4.4% across the full range of validation data, including multiple reduction cycles.     

Transformation of GO to rGO due to 8.0 MeV carbon (C++) ions irradiation and characteristics performance on MnO2–NiO–ZnO@GO electrode

The effect of 8.0 MeV carbon ions (C⁺⁺) radiations on features and performances of MnO₂–NiO–ZnO@GO electrodes (thin films). MnO₂–NiO–ZnO@GO thin films were produced using the hydrothermal technique. 8.0 MeV carbon ions (C⁺⁺) with doses of 2.25 × 10¹⁵, 5.0 × 10¹⁵, 7.5 × 10¹⁵ and 1.0 × 10¹⁶ ions/cm² were irradiated on MnO₂–NiO–ZnO@GO thin films. The XRD spectra indicate crystalline nature of the films while SEM images show rod-like structures. The XRD calculated crystallite sizes varied from 1.24 to 5.58 nm. Energy-dispersive X-ray spectroscopy, Proton induced X-ray emission (PIXE) and Rutherford back scattering (RBS) analysis are used to evaluate the elemental compositions of samples. Optical studies show reduced bandgap energies of various oxides due to the addition of graphene oxide. The electrochemical studies obtained a specific capacitance of 1627 and 1960 F/g for electrodes illuminated with radiation doses of 5.0 × 10¹⁵ and 7.5 × 10¹⁵ ions/cm², respectively. Results indicate that carbon ion irradiation with low doses improved the performances of the nanostructured thin films while radiation with high doses induces adverse disorder and flaw to the MnO₂–NiO–ZnO@GO thin film properties. These results show that ion beam irradiation is a useful tool to enhance or damage the properties of nanostructured materials depending on the dosages radiation beamed on the material.     

Modelling the effects of production rates and physico-chemical parameters on pitting rate and pit depth growth of onshore oil and gas pipelines

To estimate the pitting rate of internally corroded oil and gas gathering pipelines, a multivariate regression modelling was carried out, using pitting rates and operating parameters. These operating parameters, temperature, pH, CO₂ partial pressure, water cut, wall shear stress, chloride ion concentration, sulphate ion concentration, operating pressure, oil production rate, gas production rate and water production rate, were obtained from routine monitoring of the pipelines, whereas, the pitting rates (mean pit depths over time) were determined by the ultrasonic thickness measurement technique. The operating parameters and pitting rates were also used to estimate the pit depth growth of the pipelines using Monte Carlo simulation, and field data were used to test the developed models. The results obtained indicated that the pipelines under severe pitting corrosion rate were, more conservatively predicted than those under low, moderate and high pitting corrosion rates.     

Topology optimization parallel-computing framework based on the inherent strain method for support structure design in laser powder-bed fusion additive manufacturing

International Journal of Mechanics and Materials in Design - In this work, a topology optimization parallel-computing framework is developed to design support structures for minimizing deflections...