scholarly journals The impact of geometrical confinement in a slab on the behavior of tracer particles near active glucose oxidase micropump

2020 ◽  
Author(s):  
Raluca-Elena Munteanu ◽  
Mihail N. Popescu ◽  
Szilveszter Gáspár
Keyword(s):  
Glucose Oxidase ◽  
Glucose Solution ◽  
Microfluidic Devices ◽  
Depletion Zone ◽  
Promising Direction ◽  
Tracer Particles ◽  
Catalytically Active ◽  
Self Powered ◽  
Low Ionic Strength ◽  
The Impact

Abstract Patches of surface-immobilized and catalytically active enzyme, immersed into a solution with the corresponding substrate, induce flow in the solution. Such systems are currently investigated as a promising direction in the development of self-powered micropumps that could operate autonomously within microfluidic devices. Here, we investigate the influence of confinement, within a slab of height H, on the response exhibited by silica tracer particles sedimented near a chemically active glucose oxidase patch which is immersed into a glucose solution of very low ionic strength. Irrespective of the value H, within the range explored in this study, a region depleted of tracers forms around the patch. When H is not much larger than the radius of the patch, the rate of growth of the depletion zone depends on H; somewhat surprisingly, this dependence is influenced by the glucose concentration. The results are discussed within the context of a simple model for a chemically active patch.

scholarly journals Glucose Oxidase Micropumps: Multi-Faceted Effects of Chemical Activity on Tracer Particles Near the Solid–Liquid Interface

2019 ◽  
Vol 4 (3) ◽  
pp. 73 ◽  
Author(s):  
Raluca-Elena Munteanu ◽  
Mihail N. Popescu ◽  
Szilveszter Gáspár
Keyword(s):  
Glucose Oxidase ◽  
Areal Density ◽  
Plane Motion ◽  
Plane Region ◽  
Depletion Zone ◽  
Rate Dependent ◽  
Tracer Particles ◽  
Lateral Extent ◽  
Solid Liquid Interface ◽  
Solid Liquid

We report the development of glucose oxidase pumps characterized by small lateral dimensions (≈200 μ m). We studied the effects of the activity of the enzyme pump on silica particles (“tracers”) sedimented around the enzyme pump/patch. Once the activity of the pump was turned on (i.e., the glucose substrate was added to the solution), in-plane motion of the tracers away from the enzyme patch, as well as the emergence of an in-plane region around the patch which was depleted by tracers, was observed. The lateral extent of this depletion zone increased in time at a rate dependent both on the glucose concentration and on the areal density of the enzyme in the patch. We argue that, when the tracers were very near the wall, their motion and the emergence of the depletion zone were most likely the result of diffusiophoresis and drag by osmotic flows induced at the wall, rather than that of drag by a solutal buoyancy driven convective flow. We infer that, for the glucose oxidase enzymatic pumps, bulk (solutal buoyancy), as previously reported, as well as surface (osmotic) driven flows coexist and have to be explicitly accounted for. It seems plausible to assume that this is the case in general for enzyme pumps, and these complementary effects should be considered in the design of applications, e.g., stirring or sensing inside microfluidic systems, based on such pumps.

Overcoming stereotypes of renewable energy

2019 ◽  
pp. 124-136
Author(s):  
Victor D. Gazman
Keyword(s):  
Renewable Energy ◽  
Empirical Analysis ◽  
Energy Generation ◽  
New Paradigm ◽  
Financial Instrument ◽  
Promising Direction ◽  
Investment Projects ◽  
Power Stations ◽  
New Generation ◽  
The Impact

The article considers prerequisites for the formation of a new paradigm in the energy sector. The factors that may affect the imminent change of leadership among the energy generation are analyzed. The variability of the projects of creation and functioning of power stations is examined. The focus is made on problematic aspects of the new generation, especially, storage and supply of energy, achieving a system of parity that ensures balance in pricing generations. The author substantiates the principles of forming system of parities arising when comparing traditional and new generations. The article presents the results of an empirical analysis of the 215 projects for the construction of facilities for renewable energy. The significance and direction of the impact of these factors on the growth in investment volumes of transactions are determined. The author considers leasing as an effective financial instrument for overcoming stereotypes of renewable energy and as a promising direction for accelerated implementation of investment projects.

scholarly journals Development of Epoxy Resin-Based Elastomeric Microfluidic Devices Using CO2 Laser Ablation for DNA-Amplification Point-Of-Care (POC) Applications: Assessment of Microchannels' Dimensions and Quality

2021 ◽  
Author(s):  
Heba Mansour ◽  
Ahmed M.R. Fath El-Bab ◽  
Emad A. Soliman ◽  
Ahmed L. Abdel-Mawgood
Keyword(s):  
Laser Ablation ◽  
Epoxy Resin ◽  
Epoxy Resins ◽  
Carbon Dioxide Laser ◽  
Microfluidic Devices ◽  
Microfluidic Chips ◽  
Laser Technique ◽  
Lab On Chip ◽  
Expensive Equipment ◽  
The Impact

Abstract Microfluidic devices are a rising technology to automatize chemical and biological operations. In this context, laser ablation has significant potential for polymer-based microfluidic platforms' fast and economical manufacturing. Nevertheless, the manufacturing of epoxy-based microfluidic chips is considered highly cost full due to demand for cleanroom facilities that utilize expensive equipment and lengthy processes. Therefore, this study targeted investigating the feasibility of epoxy resins to be fabricated as a lab-on-chip using carbon dioxide laser ablation. The chemical structural properties and thermal stability of the plain epoxy resins were characterized by Fourier transform infrared spectral analysis (FT-IR) and thermogravimetric analysis (TGA). Moreover, a specific migration test was performed to quantify potential migrants by gas chromatography coupled to mass spectrometry (GC-MS) to prove that the cured epoxy resin would not release unreacted monomers to the biological solution test, which caused inhibition of the sensitive biological reactions. By investigating the impact of this process on microchannels' dimensions and quality, a laser technique using CO2 laser was used in vector mode to engrave into a transparent epoxy resin chip. The resulting microchannels were characterized using 3D Laser microscopy. The outcomes of this study showed considerable potential for laser ablation in machining the epoxy-based chips, whereas the microchannels were produced with minor bulges' height (0.027 µm) with no clogging. Moreover, a reasonable depth of 99.31 µm with roughness (Ra) of 14.52 µm was obtained at a laser speed of 5 mm/s and laser power of 1.8 W. This process can produce epoxy resin-based microfluidic chips without the need for cleanroom facilities that require expensive equipment and lengthy process.

scholarly journals Assumptions about footprint layer heights influence the quantification of emission sources: a case study for Cyprus

2017 ◽  
Vol 17 (18) ◽  
pp. 10955-10967 ◽  
Author(s):  
Imke Hüser ◽  
Hartwig Harder ◽  
Angelika Heil ◽  
Johannes W. Kaiser
Keyword(s):  
Mixing Layer ◽  
Particle Dispersion ◽  
Reasonable Assumption ◽  
Night Time ◽  
Meteorological Model ◽  
Source Contributions ◽  
Time Sensitivity ◽  
Tracer Particles ◽  
Constant Height ◽  
The Impact

Abstract. Lagrangian particle dispersion models (LPDMs) in backward mode are widely used to quantify the impact of transboundary pollution on downwind sites. Most LPDM applications count particles with a technique that introduces a so-called footprint layer (FL) with constant height, in which passing air tracer particles are assumed to be affected by surface emissions. The mixing layer dynamics are represented by the underlying meteorological model. This particle counting technique implicitly assumes that the atmosphere is well mixed in the FL. We have performed backward trajectory simulations with the FLEXPART model starting at Cyprus to calculate the sensitivity to emissions of upwind pollution sources. The emission sensitivity is used to quantify source contributions at the receptor and support the interpretation of ground measurements carried out during the CYPHEX campaign in July 2014. Here we analyse the effects of different constant and dynamic FL height assumptions. The results show that calculations with FL heights of 100 and 300 m yield similar but still discernible results. Comparison of calculations with FL heights constant at 300 m and dynamically following the planetary boundary layer (PBL) height exhibits systematic differences, with daytime and night-time sensitivity differences compensating for each other. The differences at daytime when a well-mixed PBL can be assumed indicate that residual inaccuracies in the representation of the mixing layer dynamics in the trajectories may introduce errors in the impact assessment on downwind sites. Emissions from vegetation fires are mixed up by pyrogenic convection which is not represented in FLEXPART. Neglecting this convection may lead to severe over- or underestimations of the downwind smoke concentrations. Introducing an extreme fire source from a different year in our study period and using fire-observation-based plume heights as reference, we find an overestimation of more than 60  % by the constant FL height assumptions used for surface emissions. Assuming a FL that follows the PBL may reproduce the peak of the smoke plume passing through but erroneously elevates the background for shallow stable PBL heights. It might thus be a reasonable assumption for open biomass burning emissions wherever observation-based injection heights are not available.

scholarly journals A Self-Powered Biosensor for the Detection of Glutathione

Biosensors ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 114 ◽  
Author(s):  
Brandon G. Roy ◽  
Julia L. Rutherford ◽  
Anna E. Weaver ◽  
Kevin Beaver ◽  
Michelle Rasmussen
Keyword(s):  
Detection Limit ◽  
Glucose Oxidase ◽  
Power Output ◽  
Low Cost ◽  
Linear Range ◽  
Biofuel Cell ◽  
Bilirubin Oxidase ◽  
Biological Molecule ◽  
Enzymatic Biofuel Cell ◽  
Self Powered

Glutathione is an important biological molecule which can be an indicator of numerous diseases. A method for self-powered detection of glutathione levels in solution has been developed using an enzymatic biofuel cell. The device consists of a glucose oxidase anode and a bilirubin oxidase cathode. For the detection of glutathione, the inhibition of bilirubin oxidase leads to a measurable decrease in current and power output. The reported method has a detection limit of 0.043 mM and a linear range up to 1.7 mM. Being able to detect a range of concentrations can be useful in evaluating a patient’s health. This method has the potential to be implemented as a quick, low-cost alternative to previously reported methods.

scholarly journals Decomposition of Glucose-Sensitive Layer-by-Layer Films Using Hemin, DNA, and Glucose Oxidase

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 319 ◽  
Author(s):  
Kentaro Yoshida ◽  
Yu Kashimura ◽  
Toshio Kamijo ◽  
Tetsuya Ono ◽  
Takenori Dairaku ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Glucose Oxidase ◽  
Dna Cleavage ◽  
Electrostatic Interactions ◽  
Glucose Solution ◽  
Layer By Layer ◽  
Sensitive Layer ◽  
Physiological Conditions ◽  
Lbl Films ◽  
Low Glucose

Glucose-sensitive films were prepared through the layer-by-layer (LbL) deposition of hemin-modified poly(ethyleneimine) (H-PEI) solution and DNA solution (containing glucose oxidase (GOx)). H-PEI/DNA + GOx multilayer films were constructed using electrostatic interactions. The (H-PEI/DNA + GOx)5 film was then partially decomposed by hydrogen peroxide (H2O2). The mechanism for the decomposition of the LbL film was considered to involve more reactive oxygen species (ROS) that were formed by the reaction of hemin and H2O2, which then caused nonspecific DNA cleavage. In addition, GOx present in the LbL films reacts with glucose to generate hydrogen peroxide. Therefore, decomposition of the (H-PEI/DNA + GOx)5 film was observed when the thin film was immersed in a glucose solution. (H-PEI/DNA + GOx)5 films exposed to a glucose solution for periods of 24, 48 72, and 96 h indicated that the decomposition of the film increased with the time to 9.97%, 16.3%, 23.1%, and 30.5%, respectively. The rate of LbL film decomposition increased with the glucose concentration. At pH and ionic strengths close to physiological conditions, it was possible to slowly decompose the LbL film at low glucose concentrations of 1–10 mM.

Energy-harvesting bioreactors: toward self-powered microfluidic devices, a mini-review

2020 ◽  
Vol 24 (7) ◽  
Author(s):  
Mengren Wu ◽  
Alireza Ahmadian Yazdi ◽  
Daniel Attinger ◽  
Jie Xu
Keyword(s):  
Energy Harvesting ◽  
Microfluidic Devices ◽  
Self Powered

Molecular diffusion analysis of dynamic blood flow and plasma separation driven by self-powered microfluidic devices

2021 ◽  
Vol 15 (3) ◽  
pp. 034106
Author(s):  
Sung Oh Woo ◽  
Myungkeun Oh ◽  
Kyle Nietfeld ◽  
Bailey Boehler ◽  
Yongki Choi
Keyword(s):  
Blood Flow ◽  
Molecular Diffusion ◽  
Microfluidic Devices ◽  
Plasma Separation ◽  
Diffusion Analysis ◽  
Self Powered

scholarly journals Hyperosmolarity in the small intestine contributes to postprandial ghrelin suppression

2014 ◽  
Vol 306 (12) ◽  
pp. G1108-G1116 ◽  
Author(s):  
Joost Overduin ◽  
Tracy S. Tylee ◽  
R. Scott Frayo ◽  
David E. Cummings
Keyword(s):  
Small Intestine ◽  
Glucose Solution ◽  
Jugular Vein ◽  
Gastric Bypass Surgery ◽  
Sprague Dawley ◽  
Macronutrient Composition ◽  
Sprague Dawley Rats ◽  
Small Intestinal ◽  
The Impact ◽  
Dietary Modifications

Plasma levels of the orexigenic hormone ghrelin are suppressed by meals with an efficacy dependent on their macronutrient composition. We hypothesized that heterogeneity in osmolarity among macronutrient classes contributes to these differences. In three studies, the impact of small intestinal hyperosmolarity was examined in Sprague-Dawley rats. In study 1, isotonic, 2.5×, and 5× hypertonic solutions of several agents with diverse absorption and metabolism properties were infused duodenally at a physiological rate (3 ml/10 min). Jugular vein blood was sampled before and at 30, 60, 90, 120, 180, 240, and 300 min after infusion. Plasma ghrelin was suppressed dose dependently and most strongly by glucose. Hyperosmolar infusions of lactulose, which transits the small intestine unabsorbed, and 3- O-methylglucose (3- O-MG), which is absorbed like glucose but remains unmetabolized, also suppressed ghrelin. Glucose, but not lactulose or 3- O-MG, infusions increased plasma insulin. In study 2, intestinal infusions of hyperosmolar NaCl suppressed ghrelin, a response that was not attenuated by coinfusion with the neural blocker lidocaine. In study 3, we reconfirmed that the low-osmolar lipid emulsion Intralipid suppresses ghrelin more weakly than isocaloric (but hypertonic) glucose. Importantly, raising Intralipid's osmolarity to that of the glucose solution by nonabsorbable lactulose supplementation enhanced ghrelin suppression to that seen after glucose. Hyperosmolar ghrelin occurred particularly during the initial 3 postinfusion hours. We conclude that small intestinal hyperosmolarity 1) is sufficient to suppress ghrelin, 2) may combine with other postprandial mechanisms to suppress ghrelin, 3) might contribute to altered ghrelin regulation after gastric bypass surgery, and 4) may inform dietary modifications for metabolic health.

Research of Electrochemistry Measuring System Based on Saliva Glucose

2011 ◽  
Vol 301-303 ◽  
pp. 1139-1144
Author(s):  
Li Ying Jiang ◽  
Li Jie Ren ◽  
Qing Hua Chen ◽  
Guang Zhao Cui
Keyword(s):  
Glucose Oxidase ◽  
Chemical Sensors ◽  
Linear Relation ◽  
Glucose Solution ◽  
Solution Concentration ◽  
Measuring System ◽  
Cross Linking ◽  
Glucose Content ◽  
Relationship Of ◽  
The Relationship

According to the relationship of glucose content in diabetes saliva and blood, the biosensor for detecting saliva glucose was introduced based on electrochemical detecting principle, glucose oxidase was immobilized onto the surface of electrode by glutaraldehyde cross-linking. The measuring system was designed by using potentiostat for amperometric chemical sensors. The characters of the microsystem has been demonstrated with the detection of standard glucose solution concentration of saliva parameter. Compared with the data obtained from the instrument CHI660A, it showed that has a good linear relation in the linear range of 0-2200µmol/L, with the correlation coefficient of 0.9531.

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