The goal of the current study is to propose and study an innovative method in synthesizing biocatalyst within a microfluidic reactor and later use it in the esterification of β-sitosterol. A droplet ...microreactor was specially designed and fabricated using soft-lithography technique and was used for formulation of silica nanoparticles. Sol-gel reaction method was adapted in the microreactor to produce nanoparticles which were used as the support for lipase from Rhizomucor miehei. Another microfluidics reactor was also designed and fabricated for the immobilization of the Lipase on the silica nanoparticles through a physical adsorption technique producing a biocatalyst. The catalytic efficacy of the biocatalyst was next evaluated by esterifying β-sitosterol (the main component of phytosterol) at two different catalyst loadings and comparing it to free lipase under the same experimental parameters. Samples were taken periodically and diluted with n-hexane before injecting them into gas chromatography for analysis. Spherical silica nanoparticles synthesized from the microreactor have good monodispersity with an average size of 480 nm. The silica nanoparticles produced in the microflow system showed large BET surface area, pore volume, and pore size of 125.08 m
2
/g, 0.42 cm
3
/g, and 135.70 Å, respectively. Rhizomucor miehei lipase was successfully adsorbed on the support with lipase activity around 16160 U/g. Increasing the catalyst loading increased the esterification rate from 79% to 97.3% when utilized 2.0 and 2.5 mg/ml of immobilized lipase, respectively. The findings also revealed that, under comparable reaction parameters, immobilized lipase had a higher esterification rate than free lipase.
Organic polymers were extracted from okra, aloe vera, and hibiscus leaves and used as drag‐reducing additives (DRAs) to enhance the laminar flow in custom‐made microchannels that simulate the human ...brain vessels. The experiment was conducted using an open‐loop microfluidic system. The flow enhancement performance was evaluated as the function of percentage of flow increment of mucilage additives at different concentrations. Okra mucilage showed greater flow enhancement performance at higher mucilage concentration while both aloe vera and hibiscus mucilage performed better at lower additive concentration. The findings prove the potential of these organic polymers as DRAs to enhance the blood flow.
Organic polymers were extracted from three different plant sources and used as flow enhancers in a microchannel that simulates the human brain vessels. All extracted organic polymeric additives showed high flow enhancement efficiency in the brain‐like vessels, providing great future opportunities for investigations regarding the effect of organic natural extracts on the flow in blood vessels.
Despite the efforts of mainstreaming in sports, inclusive participation of people with Intellectual Disabilities (ID) in sports remains challenging. In sports settings, the social environment may ...influence the motivation of athletes and promote (or restrict) inclusive sports participation of athletes with ID. Thus, this study aims to explore the motivations of athletes and coaches and to investigate the role of the social environment in sports participation of athletes with and without ID. Coaches who coach athletes with ID (n = 11), athletes without ID (n = 13) and both groups (n = 2) were involved in semi-structured interviews. From the inductive thematic analysis three themes were identified for the sports motivations of athletes with ID (Sport-related Progression, Social Interaction, Positive Emotions), two for their coaches' motivations (Help others, Personal and Professional Development) and four for coaching practices toward athletes with ID (Psychological and Life skills development, Building Meaningful Relationships, Behaviour adaptations and Participation-focused). Moreover, 'Teammates and Opponents' and 'Family' were classified as social agents that influence the sport participation of athletes with ID. Coaches of athletes without ID reported additional themes about their athletes' motivations (Health-related Reasons), their coaching motivations (Career aspirations) and their coaching practices towards athletes without ID (Performance-focused). The motivations of athletes and the practices of coaches could promote sports participation of athletes with ID, but more work is needed to address athletes' sports motivations and overcome the able-ist attitudes and the social oppression that may make their inclusion in sports more challenging. These sports participation barriers and facilitators could provide direction to stakeholders for developing inclusive sports pathways to people with ID.
Over the past few decades, experimental investigations have confirmed that it is not possible to enhance the flow in microfluidics channels due to its laminar flow nature. Reducing the scale of the ...carrying conduit (e.g. a microchannel) will enable the fluid properties, such as the viscosity and surface tension, to dominate and change the flow behavior. Most of the experimental efforts in this field focus on modifying the inner surfaces of the microchannels by controlling its hydrophobicity or hydrophilicity. The effect of active flow enhancement additives on the liquid flow in a microchannel is not addressed previously. The present work investigates the effect of two different types of viscoelastic additives, an anionic polymer (xanthan gum, XG) and a cationic surfactant (benzethonium chloride, BC), and their complexes on flow behavior in a 100 × 100 µm square microchannel. The effects of the additive concentrations and solution flow rates were investigated. The rheological and morphological properties of the solutions were tested using rheometer and cryo Transmission Electron Microscopy (cryo-TEM) techniques. The experimental results showed that the individual additives and their complexes can act as effective flow enhancement agents in a microchannel flow system. A maximum flow enhancement performance of 66% was achieved with the 300 ppm BC and 1000 ppm XG complex. It is believed that the interferences of the soluble additives in the microflow layers will be controlled by the aggregate size, which will result in different drag reduction behaviors.
The unique micromixing environment of microfluidic technology provides new opportunities to apply known nanoparticle formulation techniques for higher reaction rates and better product quality. Novel ...methods to formulate silica nanoparticles and immobilize Rhizomucor miehei lipase on these particles in a microflow environment are introduced. The quality of the formulated nanoparticles from the microfluidic reactor was compared with those produced in the traditional bench‐scale method. The results demonstrate that the smaller silica nanoparticles were produced from the microfluidic reactor with higher dispersity compared to nanoparticles obtained from the bench‐scale. Immobilization of lipase is found to be more effective using silica nanoparticles synthesized in microflow systems as the carriers.
Highly monodispersed silica nanoparticles were successfully synthesized in a droplet‐based microflow system. The produced nanoparticles were immobilized with Rhizomucor miehei lipase via physical adsorption in a microreactor, achieving high lipase affinity on the carriers with high immobilization yield within a short residence time.
The aim of the present work is to investigate the flow enhancement performance of an organic polymeric additive extracted from Aloe Vera in a specially designed microchannel simulating the real flow ...in the human artery. The additive rheological and flow enhancement properties were tested using a rheometer and an open-loop microfluidics flow system, respectively. The additive concentrations and solutions flow rates were the main investigated variables in the present work. The experimental results confirmed the flow enhancement effect of the new organic additive with a maximum flow enhancement up to 94% with the addition of 100 ppm of additives at 400 mbar pressure. The flow enhancement performance in heart artery-like microchannel was lower than in the straight channel due to the complexity of the design that can result in a high back pressure.
Chaotic advection method is usually implemented to design any micro-mixing device, specifically micro-mixers, where the base or the top wide surface is structured for maximum mixing performance. This ...method comes with several drawbacks, such as the high-pressure drop caused by the structured inner surface. In the present work, V-shaped micro-riblets with the riblets size ranged between 20 and 100 µm are designed and structured on the side-walls of a rectangular T-shaped micro-mixers to test its mixing and flow enhancement performances at different flow rates for single and multiple phases flow. The micro-mixers were fabricated using a direct writing method with polydimethylsiloxane as a substrate. The flow and mixing behaviors of single and multiphase flow systems were investigated through monitoring the flow of the fluids flowing through the system using micro-Particle Image Velocimetry (µ-PIV). The results showed a flow enhancement up to ∼29% for a 60 µm of base-to-height riblet at an operating pressure of ∼200 mbar for a single-phase flow system. Larger micro-riblets were found to produce a thicker laminar sub-layer within the devices that narrowed the active core of the solution. When a two-phase flow system is introduced, the flow enhancement was observed in the water phase at operating pressure > 600 mbar and riblets dimension > 60 µm. On the other hand, the maximum mixing intensity of 52% was observed in 60 µm micro-riblets size indicating that the presence of micro-structure in the micro-mixer can enhance both the flow and mixing efficiency.
Active drag reduction (DR) methods have been used to enhance flow in pipelines. Such techniques could be applied in the vasculature to improve blood flow without altering the properties of the blood. ...However, most tested DR additives have been artificial and are considered toxic. In the present work, organic mucilage from hibiscus leaves was extracted and tested with microfluidic devices simulating human heart vessels. Custom-made microchannels were connected to an open-loop micro-flow system. Pressure measurements were used to evaluate the flow enhancement performance of mucilage additives at different concentrations (100-500 ppm). Velocity profiles in the microchannels at narrowed areas were observed using a micro-particle image velocimetry system. A maximum flow increase in 63% was observed at an operating pressure of 50 mbar at 300 ppm hibiscus mucilage.
Heterogeneous reactions are considered the heart of chemical synthesis with numerous industrial applications due to their high conversion rates and low reaction time. On the other hand, the ...performance of heterogeneous reactions suffers from several drawbacks such as lower product selectivity and high mass transfer resistance that, in many cases, reduce the reaction rate. The efficiency of various conventional mixing techniques in heterogeneous reactors is believed to play a critical role in controlling the product quality and mass transfer rates besides other essential factors. Microfluidics technology provides a unique opportunity to revisit many established heterogeneous reaction processes to optimize and understand the reaction mechanisms. The unique flow conditions in microflow systems provide an excellent platform for exploring the effect of high‐precision micromixing techniques on reaction rates and productivities. Recent advances in microreactor technology in general and specifically heterogeneous reactions in microflow systems with an insight on the enzymatic reactions in microreactors are reviewed.
Microfluidic technology provides a new platform in chemical engineering to explore the known reactions, and advanced understanding in the fundamentals using microreactors. Recent applications, advances, and the possible future of microreactor technology in general and specifically in heterogeneous reactions including enzymatic reactions are reviewed and discussed.
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