Membrane Fouling During Hollow Fiber Ultrafiltration of Protein Solutions: Computational Fluid Modeling and Physicochemical Properties

Hollow fiber ultrafiltration is a viable low cost alternative technology for the concentration or separation of protein solutions. However, membrane fouling and solute build up in the vicinity of the membrane surface decrease the performance of the process by lowering the permeate flux. Major efforts have been devoted to study membrane fouling and design more efficient ultrafiltration membrane systems. The complexity of membrane fouling, however, has limited the progress to better understand and predict the occurrence of fouling. This work was motivated by the desire to develop a microscopic Computational Fluid Dynamics (CFD) model to capture the complexity of the membrane fouling during hollow fiber ultrafiltration of protein solutions. A CFD model was developed to investigate the transient permeate flux and protein concentration and the spatial fouling behavior during the concentration of electroacidified (pH 6) and non- electroacidified (pH 9) soy protein extracts by membrane ultrafiltration. Electroacidification of the soy protein to pH 6 was found to decrease the permeate flux during UF which resulted in longer filtration time. Lower electrostatic repulsion forces between the proteins at pH 6 (near the protein isoelectric point) resulted in a tighter protein accumulation on the membrane surface suggested to be responsible for the lower permeate flux observed in the UF of the electroacidified soy protein extract. A new transient two-component fouling resistance model based on the local pressure difference, permeate velocity and protein concentration was implemented in the resistance-in-series flux model to describe the dynamics of the reversible and irreversible fouling during the filtration and the effect of pH on the membrane fouling. Good agreement between the experimental data and the model predictions was observed. Mathematical modeling was performed to estimate the osmotic pressure and diffusion coefficient of the proteins bovine serum albumin (BSA) and soy glycinin, one of the major storage proteins in soy, as a function of protein concentration, pH, and ionic strength. Osmotic pressure and diffusion coefficient of proteins play vital roles in membrane filtration processes because they control the distribution of particles in the vicinity of the membrane surface, often influencing the permeation rate. Therefore, understanding the behavior of these properties is of great importance in addressing questions about membrane fouling. An artificial neural network was developed to analyze the estimated data in order to find a simple relation for osmotic pressure as a function of protein concentration, pH, and ionic strength. For both proteins, the osmotic pressure increased as pH diverged from the protein isoelectric point. Increasing the ionic strength, however, reversed the effect by shielding charges and thereby decreasing the osmotic pressure. Osmotic pressure of glycinin was found lower than that of BSA. Depending on how much pH was far from the isoelectric point of the protein, osmotic pressure of BSA could be up to three times more than the glycinin’s. Two different trends for diffusion coefficient at specified pH and ionic strength were observed for both proteins; diffusion coefficient values that decreased with protein concentration and diffusion coefficient values that passed through a maximum. A rigorous CFD model based on a description of protein interactions was developed to predict membrane fouling during ultrafiltration of BSA. BSA UF was performed in a total recycle operation mode in order to maintain a constant feed concentration. To establish a more comprehensive model and thereby alleviate the shortcomings of previous filtration models in literature, this model considered three major phenomena causing the permeate flux decline during BSA ultrafiltration: osmotic pressure, concentration polarization, and protein adsorption on the membrane surface. A novel mathematical approach was introduced to predict the concentration polarization resistance on the membrane. The resistance was estimated based on the concentration and thickness profile of the polarization layer on the membrane obtained from the solution of the equation of motion and continuity equation at a previous time step. Permeate flux was updated at each time step according to the osmotic pressure, concentration polarization resistance, and protein adsorption resistance. This model had the ability to show how microscopic phenomena such as protein interactions can affect the macroscopic behaviors such as permeate flux and provided detailed information about the local characteristics on the membrane. The model estimation was finally validated against experimental permeate flux data and good agreement was observed

Functional properties of navy bean (Phaseolus vulgaris) protein concentrates obtained by pneumatic tribo-electrostatic separation

The final publication is available at Elsevier via https://doi.org/10.1016/j.foodchem.2019.01.031 © 2019. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/A sustainable, chemical-free dry tribo-electrostatic separation approach was employed to fractionate navy bean flour. The resulting protein-enriched fractions had 36–38% protein on a moisture free basis, accounting for 43% of the total available protein. SDS-PAGE analysis of the dry-enriched protein fractions showed a similar protein profile to that of the original navy bean flour. The functional properties of these fractions were examined and compared with the commercial soybean protein concentrate as well as navy bean protein isolate obtained by a conventional wet fractionation process. These electrostatically separated protein fractions exhibited superior solubility at their intrinsic pH as well as superior emulsion stability (ES), foam expansion (FE) and foam volume stability (FVS) compared to the wet-fractionated navy bean protein isolate that was almost depleted of albumins, exhibiting poor solubility and foaming properties. These results suggest electrostatic separation as a promising route to deliver functional protein concentrates as novel food formulation ingredients.Growing Forward 2Mitacs CanadaOntario Centres of ExcellenceNatural Sciences and Engineering Researcdh CouncilHoward UniversityAdvanced CERT CanadaAgricultural Adaptation Counci

Engineering Student Experiences of Group Work

Soft skills are a crucial component for success in today’s workplace as employers increasingly value work that is collaborative and encompasses diverse perspectives. Despite this, most engineering programs fail to explicitly teach students transferable skills, including the best practices of group work. This research sought to explore how undergraduate experiences of group work change over time. This research also investigated what reflecting on cooperative education (co-op) experiences tells us about teaching group work in academic settings. Despite frequently noting the influence of group work in developing their communication skills and brainstorming ideas over time, students become somewhat more frustrated over time with their experiences of group work, mainly due to conflicting personalities and ideas among team members and/or a “slacker” student. However, our findings also show that students become more confident working in teams over time, as upper-year students were more likely to assume a leadership role and self-reported higher past performance as a group member. This study offers insights into the changing group work experiences of undergraduate engineering students as they progress through coursework and engage in experiential learning and work-integrated learning opportunities, such as co-op placements. The findings of this study can inform educators on how to best incorporate methods for teaching transferable soft skills

Engineering Student Experiences of Group Work

Soft skills are a crucial component for success in today’s workplace as employers increasingly value work that is collaborative and encompasses diverse perspectives. Despite this, most engineering programs fail to explicitly teach students transferable skills, including the best practices of group work. This research sought to explore how undergraduate experiences of group work change over time. This research also investigated what reflecting on cooperative education (co-op) experiences tells us about teaching group work in academic settings. Despite frequently noting the influence of group work in developing their communication skills and brainstorming ideas over time, students become somewhat more frustrated over time with their experiences of group work, mainly due to conflicting personalities and ideas among team members and/or a “slacker” student. However, our findings also show that students become more confident working in teams over time, as upper-year students were more likely to assume a leadership role and self-reported higher past performance as a group member. This study offers insights into the changing group work experiences of undergraduate engineering students as they progress through coursework and engage in experiential learning and work-integrated learning opportunities, such as co-op placements. The findings of this study can inform educators on how to best incorporate methods for teaching transferable soft skills

Positively Charged Gold Quantum Dots: An Nanozymatic “Off-On” Sensor for Thiocyanate Detection

The concentration of thiocyanate (SCN−) in bodily fluids is a good indicator of potential and severe health issues such as nasal bleeding, goiters, vertigo, unconsciousness, several inflammatory diseases, and cystic fibrosis. Herein, a visual SCN− sensing method has been developed using the enzyme-like nature of positively charged gold quantum dots (Au QDs) mixed with 3,3′,5,5′-tetramethylbenzidine (TMB) and hydrogen peroxide (H2O2). This research also reports a new method of synthesizing positively charged Au QDs directly from gold nanoparticles through a hydrothermal process. Microscopic imaging has showed that the Au QDs were 3–5 nm in size, and the emission wavelength was at 438 nm. Au QDs did not display any enzyme-like nature while mixed up with TMB and H2O2. However, the nanozymatic activity of Au QDs appeared when SCN− was included, leading to a very low detection limit (LOD) of 8 nM and 99–105% recovery in complex media. The steady-state kinetic reaction of Au QDs showed that Au QDs had a lower Michaelis–Menten constant (Km) toward H2O2 and TMB, which indicates that the Au QDs had a higher affinity for H2O2 and TMB than horseradish peroxidase (HRP). A mechanism study has revealed that the scavenging ability of hydroxyl (•OH) radicals by the SCN− group plays an important role in enhancing the sensitivity in this study. The proposed nanozymatic “Off–On” SCN− sensor was also successfully validated in commercial milk samples

MXene-Based Elastomer Mimetic Stretchable Sensors: Design, Properties, and Applications

Highlights MXenes, a new family of 2D nanomaterials, have been drawing notable attention due to their high electrical conductivity, processability, mechanical robustness and chemical tunability. Flexible sensors based on MXene-polymer composites are highly prospective for next-generation wearable electronics used in human–machine interfaces. With our article, we intend to fortify the bond between flexible matrices and MXenes thus promoting the swift advancement of flexible MXene-sensors for wearable technologies

Digging on the application of novel rod-like particles of polydopamine-CdTe quantum dots for photohermal cancer therapy

Trabajo presentado al RSC Chemical Nanoscience and Nanotechnology Early Careers Virtual Meeting, celebrado el 24 de marzo de 2021.Peer reviewe

Naturally Derived Carbon Dots In Situ Confined Self-Healing and Breathable Hydrogel Monolith for Anomalous Diffusion-Driven Phytomedicine Release

Fluorescent nanocarbons are well-proficient nanomaterials because of their optical properties and surface engineering. Herein, Apium graveolens-derived carbon dots (ACDs) have been synthesized by a one-step hydrothermal process without using any surplus vigorous chemicals or ligands. ACDs were captured via an in situ gelation reaction to form a semi-interpenetrating polymer network system showing mechanical robustness, fluorescent behavior, and natural adhesivity. ACDs-reinforced hydrogels were tested against robust uniaxial stress, repeated mechanical stretching, thixotropy, low creep, and fast strain recovery, confirming their elastomeric sustainability. Moreover, the room-temperature self-healing behavior was observed for the ACDs-reinforced hydrogels, with a healing efficacy of more than 45%. Water imbibition through hydrogel surfaces was digitally monitored via “breathing” and “accelerated breathing” behaviors. The phytomedicine release from the hydrogels was tuned by the ACDs’ microstructure regulatory activity, resulting in better control of the diffusion rate compared to conventional chemical hydrogels. Finally, the phytomedicine-loaded hydrogels were found to be excellent bactericidal materials eradicating more than 85% of Gram-positive and -negative bacteria. The delayed network rupturing, superstretchability, fluorescent self-healing, controlled release, and antibacterial behavior could make this material an excellent alternative to soft biomaterials and soft robotics

Naturally Derived Carbon Dots In Situ Confined Self-Healing and Breathable Hydrogel Monolith for Anomalous Diffusion-Driven Phytomedicine Release

Fluorescent nanocarbons are well-proficient nanomaterials because of their optical properties and surface engineering. Herein, Apium graveolens-derived carbon dots (ACDs) have been synthesized by a one-step hydrothermal process without using any surplus vigorous chemicals or ligands. ACDs were captured via an in situ gelation reaction to form a semi-interpenetrating polymer network system showing mechanical robustness, fluorescent behavior, and natural adhesivity. ACDs-reinforced hydrogels were tested against robust uniaxial stress, repeated mechanical stretching, thixotropy, low creep, and fast strain recovery, confirming their elastomeric sustainability. Moreover, the room-temperature self-healing behavior was observed for the ACDs-reinforced hydrogels, with a healing efficacy of more than 45%. Water imbibition through hydrogel surfaces was digitally monitored via “breathing” and “accelerated breathing” behaviors. The phytomedicine release from the hydrogels was tuned by the ACDs’ microstructure regulatory activity, resulting in better control of the diffusion rate compared to conventional chemical hydrogels. Finally, the phytomedicine-loaded hydrogels were found to be excellent bactericidal materials eradicating more than 85% of Gram-positive and -negative bacteria. The delayed network rupturing, superstretchability, fluorescent self-healing, controlled release, and antibacterial behavior could make this material an excellent alternative to soft biomaterials and soft robotics