Monitoring inverse‐phase emulsion polymerization using electrical impedance spectroscopy

Inverse‐phase emulsion polymerization (IEP) is a widely used technique for synthesizing polyacrylamide, a product in demand for water treatment and in food industries. Despite its extensive application, challenges exist in controlling and monitoring IEP due to the relatively high polymerization rate and high viscosity of polyacrylamide. We investigated IEP of acrylamide with an industrial solvent, D80, as the oil phase, azobisisobutyronitrile as an oil‐soluble initiator, and a mixture of sorbitan monooleate (Span 80) and poly(oxyethylene sorbitan trioleate) (Tween 85) as emulsifier. Our study showed that electrical impedance spectroscopy (EIS) is an efficient tool for monitoring the progress and characteristics of IEP in real time. The results revealed that the monomer conversion and polymerization rate correlate well with on‐line capacitance measurements using EIS at an appropriate frequency, while changes in conductance correlate well with changes in particle diameter which was validated using an off‐line dynamic light scattering method. © 2014 Society of Chemical Industry     

Numerical study of homogeneous–heterogeneous reactions on stagnation point flow of ferrofluid with non-linear slip condition

This study deals with the stagnation point flow of ferrofluid over a flat plate with non-linear slip boundary condition in the presence of homogeneous-heterogeneous reactions.Three kinds of ferroparticles,namely,magnetite(Fe_3O_4),cobalt ferrite(CoFe_2O_4) and manganese zinc ferrite(Mn-ZnFe_2O_4) are taken into account with water and kerosene as conventional base fluids.The developed model of homogeneous-heterogeneous reactions in boundary layer flow with equal and unequal diffusivities for reactant and autocatalysis is considered.The governing partial differential equations are converted into system of non-linear ordinary differential equations by mean of similarity transformations.These ordinary differential equations are integrated numerically using shooting method.The effects of pertinent parameters on velocity and concentration profiles are presented graphically and discussed.We found that in the presence of Fe_3O_4-kerosene and CoFe_2O_4-kerosene,velocity profiles increase for large values of α and β whereas there is a decrement in concentration profiles with increasing values of if and K_s.Furthermore,the comparison between non-magnetic(A1_2O_3) and magnetic Fe_3O_4 nanoparticles is given in tabular form.     

Designing dual phase sensing materials from polyaniline filled styrene–isoprene–styrene composites

The demand for developing oil detectors is ever increasing since the cleanup and recovery from oil spill usually take long time. Here we propose oil sensors made of polyaniline (PANI) filled poly(styrene–isoprene–styrene) (SIS) block copolymer composite films with good uniformity and dispersion. The changes in resistivity of the samples in presence of both oil and water media reveal the good sensing ability of SIS–PANI films towards oil in water (dual phase). The morphology and chemical composition of the developed products are characterized by scanning electron microscopy and Fourier transformation infrared spectroscopy. Swelling studies are performed to correlate the sensing response to the structural variations and based on it a mechanism is derived for the dual phase sensing. Contact angle measurements confirm the behavior further. The thermal properties and crystallinity of the composites are also addressed by the thermogravimetric and differential scanning calorimetric studies. The developed oil sensor material is able to withstand extreme temperature condition as well.     

Bubble hydrodynamic influence on oxygen transfer rate at presence of cationic and anionic surfactants in electroflotation process

In this work, the effects of the presence of surfactants in the liquid phase and the hydrodynamic regime of the bubble flow on the oxygen transfer rate were investigated in an electroflotation process ...     

Molecular release from painted surfaces: Free and encapsulated biocides

The current standard way of using biocide in coatings for protection against micro-organic surface growth, so called biofouling, is insufficient as the biocide leaks out from the coating too fast. In this article, we investigate a method for prolongation of the coating protection by slowing down the release rate of biocides in a controlled way. The biocide is placed into micrometer-sized reservoirs, called microspheres, from where it is slowly distributed into the coating. By different microscopic techniques the microspheres were found to be compatible (i.e. no phase separation was observed) both with the coating material and the paint. Biocide release from the coating is recorded by liquid scintillation counting and it was clear that the release is considerably slower from coatings with microspheres compared to an ordinary formulation with freely dispersed biocides. Microspheres might thus be a beneficial tool for the development of coatings with a longer protection against biofouling.     

Multiscale X-ray and Proton Imaging of Bismuth-Tin Solidification

The formation of structural patterns during metallic solidification is complex and multiscale in nature, ranging from the nanometer scale, where solid–liquid interface properties are important, to the macroscale, where casting mold filling and intended heat transfer are crucial. X-ray and proton imaging can directly interrogate structure, solute, and fluid flow development in metals from the microscale to the macroscale. X-rays permit high spatio-temporal resolution imaging of microscopic solidification dynamics in thin metal sections. Similarly, high-energy protons permit imaging of mesoscopic and macroscopic solidification dynamics in large sample volumes. In this article, we highlight multiscale x-ray and proton imaging of bismuth-tin alloy solidification to illustrate dynamic measurement of crystal growth rates and solute segregation profiles that can be that can be acquired using these techniques.     

The quest for alternatives to microbial cellulase mix production: corn stover‐produced heterologous multi‐cellulases readily deconstruct lignocellulosic biomass into fermentable sugars

BACKGROUND: Production of cellulosic ethanol is still expensive compared with corn (maize) grain ethanol due to the high costs of bulk production of microbial cellulases. At least three cellulases including endo‐cellulase, exo‐cellulase and cellobiase are needed to convert cellulosic biomass into fermentable sugars. All these cellulases could be self‐produced within cells of transgenic bio‐energy crops. The production of heterologous Acidothermus cellulolyticus (E1) endo‐cellulase in endoplasmic reticulum and mitochondria of green tissues of transgenic corn plants was recently reported, and it was confirmed that the heterologous E1 converts cellulose into fermentable sugars. RESULTS: Biologically active A. cellulolyticus E1, Trichoderma reesei 1,4‐β‐cellobiohydrolases I (CBH I) exo‐cellulase and bovine rumen Butyrivibrio fibrisolvens cellobiase were expressed in corn plant endoplasmic reticulum (ER), apoplast (cell wall areas) and vacuole respectively. Results show that the ratio 1:4:1 (E1:CBH I:cellobiase) of crude heterologous cellulases is ideal for converting ammonia fiber explosion (AFEX) pretreated corn stover into fermentable sugars. CONCLUSIONS: Corn plants that express all three biologically active heterologous cellulases within their cellulosic biomass to facilitate conversion of pretreated corn stover into fermentable sugars is a step forward in the quest for alternatives to the present microbial cellulase mix production for cellulosic biofuels. Copyright © 2011 Society of Chemical Industry     

Anticipation of future events in squirrel monkeys (Saimiri sciureus) and rats (Rattus norvegicus): Tests of the Bischof-Kohler hypothesis.

The Bischof-Kohler hypothesis holds that nonhuman animals cannot anticipate a future event and take appropriate action when that event involves satisfaction of a need not currently experienced. Tests of the Bischof-Kohler hypothesis were performed with squirrel monkeys (Saimiri sciureus) and rats (Rattus norvegicus). In experimental trials with both species, a nonthirsty animal had its water bottle removed and then chose between a smaller and larger quantity of food. Consumption of the food induced thirst. Choice of the smaller quantity led to the return of the water bottle sooner than choice of the larger quantity. Monkeys reversed their baseline preference for the larger quantity of food when the experimental contingencies were introduced, but rats continued to prefer the larger amount. Although the rat findings support the Bischof-Kohler hypothesis, the monkey findings challenge it. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Synthesis and Characterization of Anti-Scratch and Anti-Corrosion Hybrid Nanocomposite Coatings Based on Sol-Gel Process

Silicon - Hybrid nanocomposite coatings containing SiO2, TiO2, ZnO, and ZrO2 particles were synthesized based on sol-gel precursors, including tetraethoxysilane (TEOS), 3glycidoxypropyl...