A non-intrusive method is presented for measuring different fluidic properties in a microfluidic chip by optically monitoring the flow of droplets. A neural network is used to extract the desired ...information from the images of the droplets. We demonstrate the method in two applications: measurement of the concentration of each component of a water/alcohol mixture, and measurement of the flow rate of the same mixture. A large number of droplet images are recorded and used to train deep neural networks (DNN) to predict the flow rate or the concentration. It is shown that this method can be used to quantify the concentrations of each component with a 0.5% accuracy and the flow rate with a resolution of 0.05 ml/h. The proposed method can in principle be used to measure other properties of the fluid such as surface tension and viscosity.
A simple and efficient synthesis of spirooxindole derivatives by one-pot, three-component reaction of isatins, malononitrile and different nucleophiles under catalyst-free condition in deep eutectic ...solvent is reported. A series of biological importance, spirooxindole derivatives were synthesized via a multicomponent reaction of isatin, or acenaphthoquinone, and malononitrile or cyanoacetic ester with 1,3-dicarbonyl compounds, naphtol and 4-hydroxycumarin in biodegradable choline chloride based deep eutectic solvent in good yields (50–95%). This green procedure has the advantages of higher yields, shorter reaction times, environmental friendliness, and easy work-up.
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•First catalyst-free multicomponent reaction in deep eutectic solvent is explored.•The procedure gave good yields in lesser reaction times.•The biodegradable choline chloride based deep eutectic solvent was used in spirooxindole synthesis.•The developed low price deep eutectic solvents were applied as green media.
A finite element method is introduced to simulate surface tension dominated flow of two immiscible fluids featuring an enriched space for capturing both strong and weak pressure discontinuities. The ...proposed enriched finite element space is created utilizing the standard finite element shape functions. Discontinuities are captured by adding merely one additional degree of freedom per each node of the elements cut by the interface. Being local to the cut elements, these additional degrees of freedom are eliminated before assembling the global system of equations following a condensation procedure. The method is stabilized introducing a procedure for improving the conditioning of the enriched pressure contribution to the stiffness matrix in small-cut situations. An improved smoothing strategy based on an artificial diffusion equation is proposed to enhance the performance of the method on rather coarse meshes. A series of three-dimensional two-phase fluid flow benchmarks are solved to assess the performance of the method. Particular attention is paid to surface tension dominated cases. The method is verified by showing its accuracy in capturing strong pressure discontinuity at the interface of a spherical droplet as well as its capability in handling large pressure gradient discontinuity in a hydrostatic liquid–gas container. The method is further validated by simulating oscillations of a slightly disturbed spherical droplet. The mass conservation property of the method and the effect of the smoothing procedure on the result is assessed by simulating the oscillations of a prolate droplet. Ultimately, the method is tested in a more challenging setting by simulating the rising gas bubble inside a liquid domain.
•Stabilized pressure-enriched fixed-grid finite element method.•Accurate capturing of the discontinuity in the pressure and its gradient.•Condensation of the additional degrees of freedom.•Stabilization within the variational multi-scale framework.•Taylored for modeling the droplet dynamics.
PurposeThe purpose of this paper is to identify the applications and contributions of blockchain technology in finance in general, and to identify areas where the technology can make a larger impact ...in payment systems.Design/methodology/approachThe authors do an exhaustive review of blockchain technology and cryptocurrency, and examine the successful applications of blockchain technology in several finance disciplines including cryptocurrency. The authors critically evaluate the technical studies on behaviors in cryptocurrency prices.FindingsCryptocurrency is the first successful application of blockchain technology and can be used as the main fuel of the global money transfer network.Research limitations/implicationsBlockchain is a revolutionary technology that can change the world with its convenience, transparency, accuracy and efficiency in speed and cost. The growth of blockchain usage in finance depends on further familiarization and trust gained by an increasing number of proven successful usage cases and testimonials as well as appropriate legislative changes.Originality/valueThis paper provides a comprehensive review of the contributions that blockchain technology has made and is expected to make in the field of finance with the aim of adding value to corporate executives, investors, policy makers and a general audience.
•Customized Level-set/Enriched-FEM framework for moving contact-line problems.•Combination of the molecular kinetic and hydrodynamic models at the numerical level.•Level-set regularization strategy ...incorporating contact with a solid substrate.•Application of the surface tension on zero-thickness phase interface.•Accurate capturing of the contact-line dynamics in wetting problems.
A physically consistent approach is introduced to simulate dynamics of droplets in contact with solid substrates. The numerical method is developed by introducing the molecular–kinetic model within the framework of the level-set/enriched finite element method and including the theoretically resolved sub-elemental hydrodynamics. The level-set method is customized to comply fully with the model acquired for the moving contact-line. The consistency of the proposed method is verified by comparing the simulation results with the theoretical predictions. In order to further validate the method, the spreading of a droplet is numerically modeled and compared rigorously with the experimental data reported in the literature. The proposed method is also employed to capture the evolution of a droplet trapped in a conical pore. All test-cases are simulated on three-dimensional computational domains.
•Determining of rheological behavior and viscosities of sonicated starches during the ultrasound-assisted modification (UAM)•UAM mathematical and 3D computational flow dynamics simulation of various ...botanical starches.•Remarkable decrease of shear stress after sonication treatment.
The study aimed to optimize the ultrasonic-assisted modification (UAM) of corn and potato starch by assessing the influence of ultrasound geometry, power, and frequency on the fluid flow for sonicated starch to achieve porous starch with a higher degree of hydrolyzing by α-amylase. This assessment was conducted through mathematical modeling and 3D computational fluid dynamics (CFD) simulations. The ultrasonic pressure field is determined by the solution of the non-linear Westervelt equation in the frequency domain. Then, the obtained field is utilized to simulate the dissipated power and flow field characteristics. According to the results obtained from the Rapid Visco Analyzer (RVA), it was observed that the peak and final viscosity of hydrolyzed sonicated starch were less than hydrolyzed native starch. This decrease in viscosity indicates a breakdown of the starch structure, leading to a more fluid-like consistency. The shear rate and shear stress data are used for rheology modeling. The fluid's viscosity is represented based on three models of Herschel–Bulkley, Casson, and Power law (Ostwald–de Waele). The magnitude of yield shear stress at low shear rates, the shear-thinning behavior, and the nearly Newtonian fluid nature at high shear rates are extracted from the viscosity models. The surfaces of the starch granules were analyzed using scanning electron microscopy (SEM) revealed that sonication treatments caused damage, cracks, and porosity on the surfaces of the starch granules which were prone to amylolytic enzymes. This indicates that the structural integrity of the granules was compromised and facilitated enzyme penetration. This study proposes that ultrasonication can be utilized to produce damaged starch, which is susceptible to hydrolysis by α-amylase. This approach holds the potential for reducing enzyme consumption in various industries.
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► We synthesized a novel ionic liquid with two catalytic functions. ► This dual task-specific ionic liquid provides WO42- and –SO3H species. ► The catalyst is efficient for oxidation ...of cyclohexene to adipic acid.
The sole industrial process which currently used for adipic acid production is nitric acid oxidation of either cyclohexanol or cyclohexanol/cyclohexanone mixture. Emission of greenhouse nitrous oxide (N2O) gas from this process strongly contributes to global warming, resulting in acid rain and ozone depletion. Herein, we report a catalytic application of a novel dual task-specific ionic liquid (an ionic liquid with two catalytic functions) for oxidation of cyclohexene to adipic acid using 30% hydrogen peroxide. The catalyst showed desirable activity toward oxidation of cyclohexene and some cyclic olefins to produce their corresponding dicarboxylic acids.
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