Single-stage microscale solvent extraction in parallel microbore tubes using a monoblock distributor with integrated microfluidic junctions

This study is focused on the scale-up of solvent extraction in microbore tubes. A monoblock distributor with integrated microfluidic junctions (MDIMJ) is used for generating liquid–liquid dispersion and feeding the parallel microbore tubes. Experiments involve solvent extraction of U(VI) from simulated lean streams using 30% (v/v) tributyl phosphate (TBP) in dodecane. Polytetrafluoroethylene (PTFE) microbore tubes are used as a microscale contactor. The effects of inlet flow rate and O/A ratio on stage efficiency and percentage extraction (PE) are studied. Maximum capacity tested is 1.33 × 10^–6 m³/s (4.8 LPH). With O/A = 2/1, more than 90% extraction is achieved in a contact time of less than 3 s.     

Highly efficient chemoselective catalytic hydrogenation of diaryl substituted α,β-unsaturated nitriles/carbonyls using homogeneous Pd(OAc)2/PPh3 catalyst

α,β-unsaturated nitriles are chemoselectively hydrogenated to corresponding saturated nitriles with Pd(OAc)₂/PPh₃ as a homogeneous catalytic system using atmospheric pressure of molecular hydrogen. Various parameters like catalyst concentration, role of solvents, variation in the reaction temperature were screened and optimized reaction conditions were successfully used for chemoselective hydrogenation of other diaryl substituted α,β-unsaturated nitriles. The present catalytic system have also been used for hydrogenation of α,β-unsaturated carbonyls at atmospheric pressure of hydrogen.     

Global-patch-hybrid template-based arbitrary object tracking with integral channel features

Arbitrary object tracking is a challenging task in computer vision, as many factors affecting the target representation must be considered. A target template based on only the global appearance or on only the local appearance is unable to capture the discriminating information required for the robust performance of a tracker. In this paper, the target appearance is represented using a hybrid of global and local appearances along with a framework to exploit the Integral Channel Features (ICF). The proposed hybrid approach achieves fusion of the conventional global and patch-based approaches for target representation to synergize the advantages of both approaches. The ICF approach under the hybrid approach integrates heterogeneous sources of information of the target and provides feature strength to the hybrid template. The use of ICF also expedites the extraction of the structural and color features from video frames as the features are collected over multiple channels. The target appearance representation is updated based on only samples with appearances similar to the target appearance using clustering and vector quantization. These factors offer the proposed algorithm robustness to occlusion, illumination changes, and in-plane rotation. Further experimentation analyzes the effects of a change in the scale of the bounding box on the tracking performance of the proposed algorithm. The proposed approach outperforms all the state-of-the-art algorithms in all considered scenarios.     

Effect of microporous membrane properties and operating conditions on particle retention: Measurements and model studies

Depth filtration with microporous membranes has been modelled by extending upon previous approaches of Polyakov^[1–4] to incorporate pore size distribution, tortuosity, and cake buildup. The model-forecasts were benchmarked against filtration measurements performed with colloidal particles using three very different commercial membrane morphologies with the same nominal average pore size. The critical flux for each membrane was determined by a standard flux-stepping method. Particle retention and permeance were studied under constant flux or transmembrane pressure test conditions. Comparison of the forecast results with data shows reasonable qualitative agreement, but the results are very sensitive to the measurement uncertainties of the various properties.     

Living specimens under field immobilization and smartphone microscopic observation

In this work a single glycerol–water mixture, determined to be most apt at 30% (wt/vol), was used to immobilize Drosophila samples as well as to create a liquid lens for smartphone magnification viewing. This provides the advantage of being able to observe immobilized insects directly in the field rather than in the laboratory. In order to avoid having bubbles in the liquid lens and immobilizing medium that hinder visibility, an approach was developed where a stable pendant drop is moved in tandem with the dispensing tip by gravity and stopped abruptly so that sufficient momentum is transferred to the drop for its dislodgement. With 30% glycerol–water (wt/vol) mixtures, applying a minimal stroke of 10 mm with longitudinal impact delivered a momentum of 0.1464 N/s that allowed transfer of a preselected liquid volume for the processes.     

Palladium on Carbon: An Efficient,Heterogeneous and Reusable Catalytic System for Carbonylative Synthesis of N‐Substituted Phthalimides

The application of palladium on carbon (Pd/C) as a heterogeneous recyclable catalyst was investigated for the double carbonylation of o‐dihaloarenes with amines providing excellent yield of N‐substituted phthalimides in shorter reaction time as compared to earlier reported homogeneous protocols. Furthermore, the scope of the developed protocol was applied for the synthesis N‐substituted phthalimides from o‐halobenzoates and o‐halobenzoic acid via a single step carbonylative cyclization reaction. The developed methodology describes an efficient one‐step approach for the synthesis of an important class of heterocycles and tolerates a wide variety of functional groups. It circumvents the use of phosphine ligands with an additional advantage of catalyst recyclability for up to eight consecutive cycles.     

Ring‐opening polymerization of epoxy end‐terminated poly(ethylene oxide) as a route to highly crosslinked materials with exceptional swelling behavior (II)

Highly swellable poly(ethylene oxide) (PEO) gels were prepared by anionic ring‐opening polymerization of diepoxy end‐capped PEO (3400 g mol^?1) and PEO (8000 g mol^?1) using dianionic glycerol and glycolic acid initiators at scales of up to 50 g diepoxide. The glycerol‐derived materials swell to almost 20 times their mass in water. The driving force for rapid swelling appears to arise during ‘crystallization’, as segments between crosslinks are forced to pack under conditions that create high‐energy domains within the material. Solvation and therefore swelling are driven by the release of the resulting packing energy. These observations may offer insight into methods for designing other highly swellable materials. When the polyfunctional initiators have groups with different reactivities (e.g. alkoxide versus carboxylate), as might be expected, the more nucleophilic functional group appears to dominate the ring‐opening polymerization process. Copyright © 2007 Society of Chemical Industry     

Liquid–liquid mixing using micro-fluidised beds

This study experimentally investigates the application of a solid–liquid micro-fluidised bed as a micro-mixing device. The experiments were performed in a borosilicate capillary tube with an internal diameter of 1.2 mm (i.e. near the upper-limit dimension of a micro-fluidic system) using borosilicate particles with a mean diameter of 98 μm. Refractive index matching technique using sodium iodide solution was employed to achieve a transparent fluidised bed. Mixing performance of the micro-fluidised bed in terms of mixing time was investigated using a dye dilution technique. Experiments were carried out in the creeping flow regime at Reynolds numbers ranging between 0.27 and 0.72. It was demonstrated that the micro-fluidised bed mixing time sharply decreases as the Reynolds number increases. That is because at relatively high Reynolds numbers, the particle oscillation is stronger creating larger disturbances in the flow. The energy dissipation rate in micro fluidised bed was estimated to be four orders of magnitude less than other passive micro mixers which operate in the turbulent regime. It was also demonstrated that the ratio of mixing time and the energy dissipation rate for fluidised bed micro-mixer was comparable to K-M, Tangential IMTEK, and interdigital micro-mixers. However, the fluidised bed micro-mixer was found to operate at much lower Reynolds numbers compared to other passive mixers, with a mixing time of the order of few seconds.