scholarly journals Rapid flow in multilayer microfluidic paper-based analytical devices

Lab on a Chip ◽  
2018 ◽  
Vol 18 (5) ◽  
pp. 793-802 ◽  
Author(s):  
Robert B. Channon ◽  
Michael P. Nguyen ◽  
Alexis G. Scorzelli ◽  
Elijah M. Henry ◽  
John Volckens ◽  
...  
Keyword(s):  
Single Layer ◽  
Sequential Injection ◽  
Stripping Analysis ◽  
Flow Rates ◽  
Rapid Flow ◽  
Paper Device ◽  
Fast Flow

Multilayer paper devices are used to generate fast flow rates (1.56 cm s−1) which are 145-fold quicker than classical single-layer paper device designs. These self-pumping devices are demonstrated for the sequential injection stripping analysis of cadmium.

Characterization of the Mixing Performance of an Innovative Hepatic Sinusoids-Based Microreactor Using Villermaux-Dushman Protocol

2020 ◽  
Vol 1008 ◽  
pp. 28-32
Author(s):  
Mahmoud Abdelghany Shouman ◽  
Ahmed Hassan El-Shazly ◽  
Marwa Farouk El-Kady ◽  
Mohamed Nabil Sabry
Keyword(s):  
Single Layer ◽  
Industrial Applications ◽  
Low Flow ◽  
Reactor Performance ◽  
Test Reaction ◽  
Chemical Test ◽  
Flow Rates ◽  
Mixing Performance ◽  
Mixing Quality ◽  
Microreactor Technology

Microreactor technology has drawn attention in many industrial applications, especially those that requires the use of low flow rates whereas the flow is considered to be stratified. At such low flow rates, the reactor performance is usually down especially if mass transfer occurs mainly by diffusion. In the present work, the mixing performance of a novel hepatic sinusoids-based microreactor has been investigated using Villermaux–Dushman protocol. The protocol is an iodide/iodate chemical test reaction that relies on testing the absorbance of the product at 352 nm as an indication of the formation of triiodide. The investigation is carried out at low flow rates ranges from 0.5 to 3 ml/min. The novel microreactor has proven to give satisfactory performance and is easy to be fabricated as it consists of a single layer. The absorbance of light ranges between 0.29 to 0.48 resulting on the creation of limited amount of triiodide ions. It is also noticed that the mixing performance of the reactor is nearly the same over the whole studied range of flow rate. The mixing quality is also determined using another system containing 200 ppm congo red aqueous solution and pure distilled water. About 94% to 96% mixing quality is achieved.

scholarly journals Parylene-Coated Polytetrafluoroethylene-Membrane-Based Portable Urea Sensor for Real-Time Monitoring of Urea in Peritoneal Dialysate

Sensors ◽  
2019 ◽  
Vol 19 (20) ◽  
pp. 4560 ◽  
Author(s):  
Park ◽  
Kim ◽  
Kim ◽  
Pyun ◽  
Sung
Keyword(s):  
Electrode System ◽  
Optimum Concentration ◽  
Artificial Kidney ◽  
Optimum Number ◽  
Flow Conditions ◽  
Flow Rates ◽  
Peritoneal Dialysate ◽  
Amine Functionalized ◽  
Fast Flow ◽  
Optimized Conditions

A portable urea sensor for use in fast flow conditions was fabricated using porous polytetrafluoroethylene (PTFE) membranes coated with amine-functionalized parylene, parylene-A, by vapor deposition. The urea-hydrolyzing enzyme urease was immobilized on the parylene-A-coated PTFE membranes using glutaraldehyde. The urease-immobilized membranes were assembled in a polydimethylsiloxane (PDMS) fluidic chamber, and a screen-printed carbon three-electrode system was used for electrochemical measurements. The success of urease immobilization was confirmed using scanning electron microscopy, and fourier-transform infrared spectroscopy. The optimum concentration of urease for immobilization on the parylene-A-coated PTFE membranes was determined to be 48 mg/mL, and the optimum number of membranes in the PDMS chamber was found to be eight. Using these optimized conditions, we fabricated the urea biosensor and monitored urea samples under various flow rates ranging from 0.5 to 10 mL/min in the flow condition using chronoamperometry. To test the applicability of the sensor for physiological samples, we used it for monitoring urea concentration in the waste peritoneal dialysate of a patient with chronic renal failure, at a flow rate of 0.5 mL/min. This developed urea biosensor is considered applicable for (portable) applications, such as artificial kidney systems and portable dialysis systems.

PHOTOCHEMICAL SEPARATION OF MERCURY ISOTOPES: IV. THE REACTION OF Hg2026(3P1) ATOMS, PHOTOEXCITED IN NATURAL MERCURY VAPOR, WITH METHYL CHLORIDE AND ISOPROPYL CHLORIDE

1959 ◽  
Vol 37 (8) ◽  
pp. 1315-1327 ◽  
Author(s):  
K. R. Osborn ◽  
H. E. Gunning
Keyword(s):  
Flow Rate ◽  
Room Temperature ◽  
Methyl Chloride ◽  
Mercury Vapor ◽  
Progressive Increase ◽  
Temperature Data ◽  
Third Body ◽  
Flow Rates ◽  
Fast Flow ◽  
Static Conditions

A detailed investigation has been made of the reaction of Hg2026(3P1) atoms, photoexcited in natural mercury vapor (HgN), with methyl chloride, at room temperature. Data are also reported on the reaction with isopropyl chloride as substrate. Hg202 enrichment in the calomel product is taken as evidence of its formation in the primary quenching reaction.Under static conditions the methyl chloride reaction was found to form calomel with the natural Hg202 abundance (29.8%). With increasing flow rate a progressive increase in Hg202 abundance was observed. Maximum enrichments were found at fast flow rates, low substrate pressures, and high values for the absorbed light intensity (IA). The most highly enriched calomel obtained in this study contained 50.4% Hg202. With increasing IA, a corresponding increase in flow rate was required to achieve maximum Hg202 enrichment. The addition of propylene or butene-1 to the methyl chloride stream was found to result in a slight decrease in Hg202 abundance over that for the pure substrate.The isotopically specific aspects of the reaction are explained in terms of the sequence:[Formula: see text]where M represents a third body, including the wall. The decrease in enrichment observed at high substrate pressures is shown to be due to Lorentz-broadening effects on the hyperfine absorption contours of HgN. The failure to obtain enrichment under static conditions is explained by the depletion in Hg202 of the HgN in the cell through reaction [1].The investigation shows that there are two primary processes operative in the mercury-6(3P1)-photosensitized decomposition of alkyl chlorides, in one of which calomel is formed. These processes presumably involve a common short-lived intermediate R—Cl—Hg.

Inspiratory Flow Rate and Ventilation Distribution in Normal Subjects and in Patients with Simple Chronic Bronchitis

1972 ◽  
Vol 43 (5) ◽  
pp. 583-595 ◽  
Author(s):  
J. M. B. Hughes ◽  
B. J. B. Grant ◽  
R. E. Greene ◽  
L. D. Iliff ◽  
J. Milic-Emili
Keyword(s):  
Airway Resistance ◽  
Bolus Injection ◽  
Normal Subjects ◽  
Breath Holding ◽  
Ventilation Distribution ◽  
Inspiratory Flow Rate ◽  
Flow Rates ◽  
History Of ◽  
Fast Flow ◽  
Volume History

1. Seated subjects stopped ventilation briefly at end expiration while a 5 ml bolus of 133Xe was injected close to the mouth. They then inspired air at different flow rates and the distribution of radioactivity in the lungs was measured with a scanning technique during a period of breath-holding at maximal inspiration. 2. In five normal subjects the dependent zones received a greater fraction of the 133Xe bolus than the apex during slow inspirations, but apical distribution exceeded basal for fast inspirations. The volume history of the lungs before the bolus injection had no effect on the slow/fast difference in four out of five subjects. 3. In five patients with clinical bronchitis but normal forced expired volume, dependent zone ventilation was much reduced on a slow inspiration compared with normals, but at fast flow rates the distribution was normal. 4. Insofar as the bolus in the fast inspiration was distributed according to regional airway conductances, these results suggest that in normal subjects differences in airway resistance exist between the upper and lower zones of the upright lung. An early abnormality in bronchitis appears to be a reduction of compliance in the dependent zones, as judged from the decrease in basal ventilation on a slow inspiration.

Melt Compounding Based Rotational Foam Molding Technology for Manufacture of Polypropylene Foams

2002 ◽  
Vol 21 (2) ◽  
pp. 101-120 ◽  
Author(s):  
Remon Pop-Iliev ◽  
Chul B. Park
Keyword(s):  
Raw Materials ◽  
Single Layer ◽  
Flow Rates ◽  
Melt Compounding ◽  
Processing Strategies ◽  
Single Piece ◽  
Wide Range ◽  
Parametric Search ◽  
Twin Screw ◽  
Material Preparation

This paper is intended to provide an engineering understanding of the technological potentials for processing polypropylene (PP) foams in rotational foam molding. A process proposal, based on the melt compounding material-preparation approach, capable of producing completely foamed, single-layer, single-piece PP products in rotational foam molding, is disclosed in detail. It comprises dispersing a chemical blowing agent (CBA) in the PP matrix using a twin-screw compounder, pelletizing the obtained expandable composition, and then producing foams in an uninterrupted rotational foam molding cycle by using the pre-compounded foamable pellets. Several PP grades were deliberately selected to cover a wide range of melt flow rates (MFR), starting from 5.5 up to 35 dg/min. After the raw materials participating in the study were characterized using thermal analysis instrumentation, different foamable compositions were formulated in order to prepare both 3-fold and 6-fold foamable pellets from each PP grade. The optimal foam processing strategies were identified via a systematic experimental parametric search. Foams with the best cell morphologies were obtained out of the high melt strength PP grades. In addition, the experimental results revealed that the cell morphology of the processed PP foams is not as good as that of respective PE foams. However, the cell morphologies of the PP foams processed by using the melt compounding-based approach demonstrated significant improvements in comparison with those processed by using the dry blending-based approach.

scholarly journals Parylene-Coated PTFE-Membrane-Based Portable Urea Sensor for Use in Fast Flow Conditions

2019 ◽  
Author(s):  
Min Park ◽  
JeeYoung Kim ◽  
Kyounghee Kim ◽  
Jae-Chul Pyun ◽  
Gun Yong Sung
Keyword(s):  
Flow Condition ◽  
Electrode System ◽  
Optimum Concentration ◽  
Optimum Number ◽  
Flow Conditions ◽  
Flow Rates ◽  
Ptfe Membrane ◽  
Amine Functionalized ◽  
Fast Flow ◽  
Optimized Conditions

A portable urea sensor for use in the fast flow condition was fabricated using porous polytetrafluoroethylene (PTFE) membranes coated with amine-functionalized parylene, parylene-A, by vapor deposition. To generate a specific electrochemical sensor signal from urea, the urea-hydrolyzing enzyme urease was immobilized on the parylene-A-coated PTFE membranes via chemical crosslinking using glutaraldehyde. The urease-immobilized membranes were assembled in a polydimethylsiloxane (PDMS) fluidic chamber, and a screen-printed carbon three-electrode system was used for electrochemical measurements. The success of urease immobilization was confirmed using fluorescence microscopy, scanning electron microscopy, and Fourier-transform infrared spectroscopy. The optimum concentration of urease for immobilization on the parylene-A-coated PTFE membranes was determined to be 48 mg/mL, and the optimum number of membranes in the PDMS chamber was found to be 8. Using these optimized conditions, we fabricated the urea biosensor and monitored urea samples under various flow rates ranging from 0.5 to 10 mL/min in the flow condition using chronoamperometry. To test the applicability of the sensor for physiological samples, we used it for monitoring urea concentration in the waste peritoneal dialysate of a patient with chronic renal failure, at a flow rate of 0.5 mL/min.

scholarly journals FACTORS AFFECTING THE ADHESIVENESS OF HUMAN LEUCOCYTES AND PLATELETS IN VITRO

1961 ◽  
Vol 114 (1) ◽  
pp. 51-73 ◽  
Author(s):  
James E. Garvin
Keyword(s):  
Calcium Ions ◽  
Glass Bead ◽  
Divalent Cations ◽  
Polymorphonuclear Neutrophils ◽  
Chelating Resin ◽  
Column Length ◽  
Flow Rates ◽  
Factors Affecting ◽  
Rapid Flow

Some factors affecting the retention of human polymorphonuclear neutrophils (PMN), lymphocytes, and platelets on a siliconized glass bead column were explored. PMN were more effectively retained when the flow rates were slow and the columns long. They were found largely on the upper portions of the columns except with rapid flow rates when they spread down the columns. PMN retention on the columns was greatest in the range 30°–43°C. Both magnesium and calcium ions were required for full adhesiveness; calcium ions alone were unable to restore adhesiveness to PMN from blood which had been treated with a chelating resin to remove divalent cations. The adhesiveness of the PMN was independent of cyanide and dinitrophenol, but was almost completely eliminated by iodoacetamide. Under all the conditions mentioned above in which adhesiveness was lost there was a concurrent loss of the usual ability of the PMN to migrate, but at least in the presence of EDTA, a capacity to change shape by pseudopod formation remained. Lymphocytes were retained on the columns to a much lesser extent than the PMN under all conditions and, within limits, this retention was not related to either flow rate or column length. Maximum lymphocyte retention occurred in the range 30°–43°C. No dependence of lymphocyte adhesiveness was shown for divalent cations, cyanide, dinitrophenol, or iodoacetamide, but such dependence is not excluded by the data obtained. Platelets were largely retained by the glass bead columns under most conditions and this was unrelated to temperature in the range 0°–50°C. Their adhesiveness was found to require either magnesium or calcium ions and to be blocked by iodoacetamide.

Computational Study and Optimization of Laminar Heat Transfer and Pressure Loss of Double-Layer Microchannels for Chip Liquid Cooling

2013 ◽  
Vol 5 (1) ◽  
Author(s):  
Gongnan Xie ◽  
Yanquan Liu ◽  
Bengt Sunden ◽  
Weihong Zhang
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Double Layer ◽  
Flow Rate ◽  
Single Layer ◽  
Parallel Flow ◽  
Heat Fluxes ◽  
Liquid Cooling ◽  
Counter Flow ◽  
Flow Rates

The problem involved in the increase of the chip output power of high-performance integrated electronic devices is the failure of reliability because of excessive thermal loads. This requires advanced cooling methods to be incorporated to manage the increase of the dissipated heat. The traditional air-cooling can not meet the requirements of cooling heat fluxes as high as 100 W/cm2, or even higher, and the traditional liquid cooling is not sufficient either in cooling very high heat fluxes although the pressure drop is small. Therefore, a new generation of liquid cooling technology becomes necessary. Various microchannels are widely used to cool the electronic chips by a gas or liquid removing the heat, but these microchannels are often designed to be single-layer channels with high pressure drop. In this paper, the laminar heat transfer and pressure loss of a kind of double-layer microchannel have been investigated numerically. The layouts of parallel-flow and counter-flow for inlet/outlet flow directions are designed and then several sets of inlet flow rates are considered. The simulations show that such a double-layer microchannel can not only reduce the pressure drop effectively but also exhibits better thermal characteristics. Due to the negative heat flux effect, the parallel-flow layout is found to be better for heat dissipation when the flow rate is limited to a low value while the counter-flow layout is better when a high flow rate can be provided. In addition, the thermal performance of the single-layer microchannel is between those of parallel-flow layout and counter-flow layout of the double-layer microchannel at low flow rates. At last, the optimizations of geometry parameters of double-layer microchannel are carried out through changing the height of the upper-branch and lower-branch channels to investigate the influence on the thermal performance.

Mechanism underlying flow stimulation of sodium absorption in the mammalian collecting duct

2006 ◽  
Vol 291 (3) ◽  
pp. F663-F669 ◽  
Author(s):  
Tetsuji Morimoto ◽  
Wen Liu ◽  
Craig Woda ◽  
Marcelo D. Carattino ◽  
Yuan Wei ◽  
...  
Keyword(s):  
Flow Rate ◽  
Membrane Trafficking ◽  
Collecting Duct ◽  
Extracellular Fluid ◽  
Brefeldin A ◽  
Sodium Absorption ◽  
Laminar Shear Stress ◽  
Open Probability ◽  
Flow Rates ◽  
Fast Flow

Vectorial Na+ absorption across the aldosterone-sensitive distal nephron plays a key role in the regulation of extracellular fluid volume and blood pressure. Within this nephron segment, Na+ diffuses from the urinary fluid into principal cells through an apical, amiloride-sensitive, epithelial Na+ channel (ENaC), which is considered to be the rate-limiting step for Na+ absorption. We have reported that increases in tubular flow rate in microperfused rabbit cortical collecting ducts (CCDs) lead to increases in net Na+ absorption and that increases in laminar shear stress activate ENaC expressed in oocytes by increasing channel open probability. We therefore examined whether flow stimulates net Na+ absorption ( JNa) in CCDs by increasing channel open probability or by increasing the number of channels at the apical membrane. Both baseline and flow-stimulated JNa in CCDs were mediated by ENaC, as JNa was inhibited by benzamil. Flow-dependent increases in JNa were observed following treatment of tubules with reagents that altered membrane trafficking by disrupting microtubules (colchicine) or Golgi (brefeldin A). Furthermore, reducing luminal Ca2+ concentration ([Ca2+]) or chelating intracellular [Ca2+] with BAPTA did not prevent the flow-dependent increase in JNa. Extracellular trypsin has been shown to activate ENaC by increasing channel open probability, and we observed that trypsin significantly enhanced JNa when tubules were perfused at a slow flow rate. However, trypsin did not further enhance JNa in CCDs perfused at fast flow rates. Similarly, the shear-induced increase in benzamil-sensitive JNa in oocytes expressing protease resistance ENaC mutants was similar to that of controls. Our results suggest the rise in JNa accompanying increases in luminal flow rates reflects an increase in channel open probability.

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