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Full-Text Articles in Physical Sciences and Mathematics

Two-Ply Channels For Faster Wicking In Paper-Based Microfluidic Devices, Conor K. Camplisson, Kevin M. Schilling, William L. Pedrotti, Howard A. Stone, Andres W. Martinez Oct 2015

Two-Ply Channels For Faster Wicking In Paper-Based Microfluidic Devices, Conor K. Camplisson, Kevin M. Schilling, William L. Pedrotti, Howard A. Stone, Andres W. Martinez

Chemistry and Biochemistry

This article describes the development of porous two-ply channels for paper-based microfluidic devices that wick fluids significantly faster than conventional, porous, single-ply channels. The two-ply channels were made by stacking two single-ply channels on top of each other and were fabricated entirely out of paper, wax and toner using two commercially available printers, a convection oven and a thermal laminator. The wicking in paper-based channels was studied and modeled using a modified Lucas–Washburn equation to account for the effect of evaporation, and a paper-based titration device incorporating two-ply channels was demonstrated.


The Effect Of Drought On Stomatal Conductance In The Biosphere 2 Rainforest, Justin Gay, Joost Van Haren Aug 2015

The Effect Of Drought On Stomatal Conductance In The Biosphere 2 Rainforest, Justin Gay, Joost Van Haren

STAR Program Research Presentations

Drought is a major climate change concern for the Earth’s rainforests; however little is currently known about how these forests and individual plants will respond to water stress. At the individual level, the ability of plants to regulate their stomatal conductance is an important preservation mechanism that helps to cool leaves, regulate water loss, and uptake carbon dioxide. At the ecosystem level, transpiration in rain forests is a major contributor to the feedback loop that returns moisture to the atmosphere for continued rains. Nearly 60% of atmospheric moisture in the Amazon rain forests has been traced back to origins of …


Evaluation Of Anthropogenic Marine Debris And Sargassum Fluitans And Its Potential Impact On Sea Turtle Hatchlings At Sandy Point National Wildlife Refuge, Christina Macmillan Aug 2015

Evaluation Of Anthropogenic Marine Debris And Sargassum Fluitans And Its Potential Impact On Sea Turtle Hatchlings At Sandy Point National Wildlife Refuge, Christina Macmillan

STAR Program Research Presentations

Anthropogenic debris, particularly plastic, has become a significant threat for marine species with the increased use of plastics over the years. Marine birds and sea turtles, mostly green, loggerhead and leatherback turtles, are especially vulnerable to mistaking plastic debris for food and ingesting it. There has been a rise in the incidence of turtles having plastic fragments in their GI tracts; even small amounts of plastic may have major long-term health and reproductive effects. On the nesting beaches, both adults and hatchlings may become entangled in debris or have trouble navigating around beach debris during their crawl to the sea. …


Radiocarbon Isotopic Classification Of Deep Tropical Forest Soils, Brooke Butler, Karis J. Mcfarlane, Jennifer Pett-Ridge, Katherine A. Heckman Aug 2015

Radiocarbon Isotopic Classification Of Deep Tropical Forest Soils, Brooke Butler, Karis J. Mcfarlane, Jennifer Pett-Ridge, Katherine A. Heckman

STAR Program Research Presentations

Tropical forest soils have an important role in global carbon (C) stocks. Small changes in the cycling of C could drastically affect atmospheric carbon dioxide (CO2) concentrations and active cycling of carbon in a forest community. Currently, little is understood of how tropical forest soils will respond to the increasing global temperatures. To examine the effects of warming/ drought on losses of older versus younger soil C pools, we implemented radiocarbon (14C) isotopic characterization of various soil plot samples and depths from the Luquillo Experimental Forest, Puerto Rico. 14C was measured using Accelerated Mass Spectrometry (AMS) from catalytically condensed carbon …


Poly(N-Isopropylacrylamide) Hydrogels For Storage And Delivery Of Reagents To Paper-Based Analytical Devices, Haydn T. Mitchell, Spencer Schultz, Philip Costanzo, Andres W. Martinez Jul 2015

Poly(N-Isopropylacrylamide) Hydrogels For Storage And Delivery Of Reagents To Paper-Based Analytical Devices, Haydn T. Mitchell, Spencer Schultz, Philip Costanzo, Andres W. Martinez

Chemistry and Biochemistry

The thermally responsive hydrogel N,N'-methylenebisacrylamide-cross-linked poly(N-isopropylacrylamide) (PNIPAM) was developed and evaluated as a reagent storage and delivery system for microfluidic paper-based analytical devices (microPADs). PNIPAM was shown to successfully deliver multiple solutions to microPADs in specific sequences or simultaneously in laminar-flow configuration and was found to be suitable for delivering four classes of reagents to the devices: Small molecules, enzymes, antibodies and DNA. PNIPAM was also able to successfully deliver a series of standard glucose solutions to microPADs equipped to perform a colorimetric glucose assay. The results of these tests were used to produce an external calibration …


Reagent Pencils: A New Technique For Solvent-Free Deposition Of Reagents Onto Paper-Based Microfluidic Devices, Haydn T. Mitchell, Isabelle C. Noxon, Cory A. Chaplan, Samantha J. Carlton, Cheyenne H. Liu, Kirsten A. Ganaja, Nathaniel W. Martinez, Chad Immoos, Philip Costanzo, Andres W. Martinez Apr 2015

Reagent Pencils: A New Technique For Solvent-Free Deposition Of Reagents Onto Paper-Based Microfluidic Devices, Haydn T. Mitchell, Isabelle C. Noxon, Cory A. Chaplan, Samantha J. Carlton, Cheyenne H. Liu, Kirsten A. Ganaja, Nathaniel W. Martinez, Chad Immoos, Philip Costanzo, Andres W. Martinez

Chemistry and Biochemistry

Custom-made pencils containing reagents dispersed in a solid matrix were developed to enable rapid and solvent-free deposition of reagents onto membrane-based fluidic devices. The technique is as simple as drawing with the reagent pencils on a device. When aqueous samples are added to the device, the reagents dissolve from the pencil matrix and become available to react with analytes in the sample. Colorimetric glucose assays conducted on devices prepared using reagent pencils had comparable accuracy and precision to assays conducted on conventional devices prepared with reagents deposited from solution. Most importantly, sensitive reagents, such as enzymes, are stable in the …