UDCaT-4: a novel mesoporous superacid catalyst in the selective synthesis of 4,4′-diisopropylbiphenyl by the isopropylation of biphenyl

A novel superacidic mesoporous catalyst UDCaT-4 was developed in this laboratory, which has been used in the alkylation of biphenyl with isopropanol. UDCaT-4 is a synergistic combination of persulfated alumina and zirconia with hexagonal mesoporous silica. 4,4′-Diisopropylbiphenyl (DIPB) has been increasingly used as an intermediate for manufacturing polymers and films possessing high heat resistance and strength. A variety of solid acid catalysts, especially zeolites, are reported for the alkylation of biphenyl to make DIPB but all of them e.g. mordenites, ZSM-5, H-β etc. suffer from coke formation and require regeneration within a few hours of time-on-stream. We report the efficacy of UDCaT-4, which exhibits tremendous stability, activity and selectivity in the vapor phase isopropylation of biphenyl with isopropanol to DIPB. A systematic investigation of the effects of various operating parameters is done. Furthermore, a mathematical model is developed to describe the reaction kinetics which is validated with experimental results.     

Materials Challenges in Reverse‐Flow Pyrolysis Reactors for Petrochemical Applications

Currently, the pyrolysis of hydrocarbons for the production of light olefins is almost exclusively carried out in steam crackers operating around 900–1000°C. However, cracking hydrocarbons at much higher temperature results in high selectivity to acetylene, which can be converted into many petrochemical products including ethylene. The desired hydropyrolysis reaction from hydrocarbons to acetylene can be realized in a reverse‐flow reactor at very high temperatures (>1700°C) in a scalable manner. The reactor elements include ceramic components that are placed in the hottest regions of the reactor and must withstand a temperature that is in the range of 1500–2000°C. In addition, the temperature rises and falls with the reverse‐flow cycle; a fluctuation that could be as high as 100–500°C over a period of several seconds. Moreover, the materials in the hot zone are exposed alternately to a regeneration (heat addition) step that is mildly oxidizing, and a pyrolysis (cracking) step that is strongly reducing with a correspondingly high carbon activity. This article addresses the thermodynamic stability of selected ceramic materials based on alumina, zirconia, and yttria for such an application. Results from laboratory tests involving the exposure of these ceramic materials to simulated process conditions followed by their microstructural characterization are compared with expectations from thermodynamic predictions.     

Castor-oil derived nonhalogenated reactive flame-retardant-based polyurethane foams with significant reduced heat release rate

National Fire Protection Association encounters one structural fire every 66 s. Rigid polyurethane foam is one of the principal components used in constructional and household applications. In this work, a reactive flame retardant (FR) was synthesized using a facile one-step thiol–ene reaction by reacting mercaptenized castor oil (MCO) and diethyl allyl phosphonate (DEAP). The obtained MCO–DEAP polyol was used for the preparation of polyurethanes having different weight percentages of phosphorus (P). Addition of FR polyol showed no adverse effect on the cellular structure of the foams and maintained the compressive strength. All the foams showed closed cell content greater than 95%. Horizontal burning test (HBT) was performed before and after the migration test to understand the stability of the FR within the foams. Foams showed no relative weight loss before and after the migration test and maintained equivalent results for HBT. For 1.5 wt % P foams, low extinguishing time of 3 s and weight loss of 4% was observed. The cone calorimeter test showed a reduction in the peak heat release rate from 313 to 158 kW m⁻³, the total heat release from 18 to 8 MJ m⁻², and O₂ consumption from 12 to 6 g. Our results suggest that MCO–DEAP polyol could act as an essential FR for rigid PU foam ensuring fire safety. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47276.     

Miniaturized polymeric enzymatic biofuel cell with integrated microfluidic device and enhanced laser ablated bioelectrodes

The present work establishes a simple, customized, and economical laser-induced graphene (LIG) material produced using a CO₂ laser. The one-step LIG bioelectrodes have been further validated for Enzymatic Biofuel Cell (EBFC) application by integrating them into a microfluidic device, fabricated by the conventional soft-lithography on Polydimethylsiloxane (PDMS). This electrode and device manufacturing technology delivers a simple and quick fabrication method, which eliminates the necessity of any further amendment and post-processing. LIG electrodes were created at optimized CO₂ laser (5.1 W power and 0.625 cm s^?1 speed) irradiation which has been further modified by Multi-walled carbon nanotubes (CNT), called C-LIG electrodes, which offers improved performance and enzyme stability. In this novel study, CNT functionalized LIG electrodes have been incorporated into a microfluidic device for biofuel cell applications. LIG and C-LIG bioelectrodes have been integrated into a microfluidic device under the laminar fluid flow regime and the electrochemical and polarization study of the platform have been carried out. This C-LIG bioelectrodes integrated microfluidic device, without any metal catalyst, generated 2.2 μW/cm² power density with an optimized 200 μl/min flow rate which is 1.37 times higher than the LIG bioelectrodes. Such novel and simple EBFC platform is amenable to further improvement for generating even more power output by optimizing the LIG formation, alternate nano-functionalisation and mediator based electrochemical analysis.     

Microfluidic paper microbial fuel cell powered by Shewanella putrefaciens in IoT cloud framework

The present work demonstrates a miniaturized, easily fabricated, environment-friendly, and cost-effective Microfluidic Paper-based Microbial Fuel Cell (MPMFC) as a potential Energy Harvesting Device. The device consists of a microchannel with a reductant (Shewanella putrefaciens exoelectrogen bacterium with L.B Broth) and oxidant (aerated tap water) flowing over Carbon electrode (anode) and Silver electrode (cathode) using co-laminar flow with the self-capillary phenomenon. The electrochemical analysis like Polarization, Open Circuit Voltage (OCV) was evaluated using a potentiostat, and conductivity and sheet resistance were evaluated using a four-point probe instrument. Various bacterial studies, like growth curve study (Optical Density), volumetric concentrations, and incubation time, were carried out to find out the best suitable optimal bacterial conditions. Lastly, detailed element composition study and morphology of the surface of the electrode with biofouling was carried out using Energy Dispersive Spectroscopy (EDS) and Scanning Electron Microscopy (SEM) techniques, respectively. The portable MPMFC yields a maximum power density of 15.4 μW/cm² (1340 nA/cm²) at 390 mV over 90 μL of culture. Also, An Internet of Things (IoT)/cloud-based hardware has been developed and integrated with MPMFC platform to observe the real-time device performance leading to its long-lasting potential to operate miniaturized microelectronics sensors and portable devices.     

Detection of novel coronavirus from chest X-rays using deep convolutional neural networks

Multimedia Tools and Applications - With over 172 Million people infected with the novel coronavirus (COVID-19) globally and with the numbers increasing exponentially, the dire need of a fast...     

Quantifying microstructures in isotropic grain growth from phase field modeling: Methods

While digital microstructures can be produced using various numerical models, quantitative characterization of these microstructures is often limited to a few attributes, such as grain diameter, the number of faces per grain and their distributions. A large number of topological and geometric properties that are useful for both experimental and theoretical analysis of microstructure–property relations have yet to be explored. To address this problem, we developed a series of numerical methods to compute geometric and topological properties of the microstructures. To test these methods, we performed a quantitative analysis of the digital microstructures obtained from a phase field simulation during isotropic grain growth. The new characterization methods allow us to not only identify each individual microstructure entity, including grain cell, grain boundary interface, triple junction line and vertex point, but also calculate the interface area, the triple junction length, and the curvature of grain boundary interfaces and triple junction lines. The detailed time evolution of these microstructural attributes, particularly the distributions of interface area and the length of triple junction lines, is extracted during the grain-coarsening process. The quantitative information gives us a detailed picture of grain growth in the phase field model that has not been seen before. Both the quantitative microstructures and the dynamic behavior are expected to serve as a benchmark for comparison to the microstructures obtained from other methods, including experiments.     

High Yttria–Zirconia and Yttria Ceramics for Petrochemical Reverse‐Flow Reactor Applications

Reverse‐flow reactors achieve the desired hydropyrolysis reaction of natural gas and other hydrocarbon feeds at very high temperatures of up to 2000°C, which enables the production of many high‐value chemicals. To identify refractory ceramic materials suitable for constructing key components of the reactor, the full range of solid solutions between zirconia and yttria having 18 to 100 mol% yttria have been tested in a laboratory reactor. Conventional yttria‐stabilized zirconia (YSZ) materials having 8 mol% Y₂O₃ appear to accommodate reactor thermal severity, but are prone to a new form of corrosion termed ceramic dusting that is observed when pyrolysis and oxidation cycles are alternated under reverse‐flow conditions. Yttria and high yttria–zirconia ceramics having ~80 mol% or more yttria suppress ceramic dusting corrosion in steam‐free pyrolysis environments. The addition of low levels of steam of ~5% to the pyrolysis gas stream increases the stability of YSZ materials substantially, so that the stability threshold is closer to 40 mol% Y₂O₃ in the yttria–zirconia system. The two approaches can be combined to optimize reactor performance. Key experimental results are presented and discussed taking into account the thermodynamic phase stability of the different phases.     

Injection of biosurfactant and chemical surfactant following hot water injection to enhance heavy oil recovery

This study investigates the potential of enhancing oil recovery from a Middle East heavy oil field via hot water injection followed by injection of a chemical surfactant and/or a biosurfactant produced by a Bacillus subtilis strain which was isolated from oil-contaminated soil. The results reveal that the biosurfactant and the chemical surfactant reduced the residual oil saturation after a hot water flood. Moreover, it was found that the performance of the biosurfactant increased by mixing it with the chemical surfactant. It is expected that the structure of the biosurfactant used in this study was changed when mixed with the chemical surfactant as a probable synergetic effect of biosurfactant-chemical surfactants was observed on enhancing oil recovery, when used as a mixture, rather than alone. This work proved that it is more feasible to inject the biosurfactant as a blend with the chemical surfactant, at the tertiary recovery stage. This might be attributed to the fact that in the secondary mode, improvement of the macroscopic sweep efficiency is important, whereas in the tertiary recovery mode, the microscopic sweep efficiency matters mainly and it is improved by the biosurfactant-chemical surfactant mixture. Also as evidenced by this study, the biosurfactant worked better than the chemical surfactant in reducing the residual heavy oil saturation after a hot water flood.     

Molecularly Hybridized Conduction in DPP-Based Donor–Acceptor Copolymers toward High-Performance Iono-Electronics

Iono-electronics, that is, transducing devices able to translate ionic injection into electrical output, continue to demand a variety of mixed ionic–electronic conductors (MIECs). Though polar sidechains are widely used in designing novel polymer MIECs, it remains unclear to chemists how much balance is needed between the two antagonistic modes of transport (ion permeability and electronic charge transport) to yield high-performance materials. Here, the impact of molecularly hybridizing ion permeability and charge mobility in semiconducting polymers on their performance in electrochemical and synaptic transistors is investigated. A series of diketopyrrolopyrrole (DPP)-based copolymers are employed to demonstrate the multifunctionality attained by controlling the density of polar sidechains along the backbone. Notably, efficient electrochemical signal transduction and reliable synaptic plasticity are demonstrated via controlled ion insertion and retention. The newly designed DPP-based copolymers further demonstrate unprecedented thermal tolerance among organic mixed ionic–electronic conductors, a key property in the manufacturing of organic electronics.