Physical Sciences and Mathematics Commons^™

Pressure Driven Desalination Utilizing Nanomaterials, Fangyou Xie

Master's Theses

Nanomaterials such as graphene oxide and carbon nanotubes, have demonstrated excellent properties for membrane desalination, including decrease of maintenance, increase of flux rate, simple solution casting, and impressive chemical inertness. Here, two projects are studied to investigate nanocarbon based membrane desalination. The first project is to prepare hybrid membranes with amyloid fibrils intercalated with graphene oxide sheets. The addition of protein amyloid fibrils expands the interlayer spacing between graphene oxide nanosheets and introduces additional functional groups in the diffusion pathways, resulting in increase of flux rate and rejection rate for the organic dyes. Amyloid fibrils also provide structural assistance to …

Analysis Of Biofilm Remediation Capacity For Octenyl Succinic Anhydride (Osa), A Bioactive Food Starch Modifier Compound, Matthew R. Borglin

Master's Theses

Matthew R. Borglin

This thesis demonstrates efficacy of Octenyl Succinic Anhydride (OSA), as a biofilm sanitizer. Biofilms allow bacteria to adhere to solid surfaces with the use of excreted polymeric compounds. For example, surfaces found in food production or processing facilities such as the interior of a raw milk holding tank, are some of the most susceptible to biofilm contamination. When present, biofilms can cause a variety of negative effects, which include; reduction of product shelf life, corrosion, and outbreaks of foodborne illnesses. The close association of biofilms with the majority of foodborne illness cases led the US Environmental Protection …

Fabrication Of Miniaturized Paper-Based Microfluidic Devices (Micropads), E. Brandon Strong, Spencer A. Schultz, Andres Martinez, Nathaniel W. Martinez

Chemistry and Biochemistry

Microfluidic paper-based analytical devices (microPADs) are emerging as cost-effective and portable platforms for point-of-care assays. A fundamental limitation of microPAD fabrication is the imprecise nature of most methods for patterning paper. The present work demonstrates that paper patterned via wax printing can be miniaturized by treating it with periodate to produce higher-resolution, high-fidelity microPADs. The optimal miniaturization parameters were determined by immersing microPADs in various concentrations of aqueous sodium periodate (NaIO₄) for varying lengths of time. This treatment miniaturized microPADs by up to 80% in surface area, depending on the concentration of periodate and length of the reaction …

Adapting Cell-Free Protein Synthesis As A Platform Technology For Education, Grace W. Chu, Max Z. Levine, Nicole E. Gregorio, Javin P. Oza

STAR Program Research Presentations

Cell-free protein synthesis (CFPS) has emerged as an enabling biotechnology for research and biomanufacturing as it allows for the production of protein without the need for a living cell. Applications of CFPS include the construction of libraries for functional genomics and structural biology, the production of personalized medicine, and the expression of virus-like particles. The absence of a cell wall provides an open platform for direct manipulation of the reaction conditions and biological machinery. This project focuses on adapting the CFPS biotechnology to the classroom, making a hands-on bioengineering approach to learning protein synthesis accessible to students grades K-16 through …

Characterization Of Reagent Pencils For Deposition Of Reagents Onto Paper-Based Microfluidic Devices, Cheyenne H. Liu, Isabelle C. Noxon, Leah E. Cuellar, Amanda L. Thraen, Chad Immoos, Andres W. Martinez, Philip J. Costanzo

Chemistry and Biochemistry

Reagent pencils allow for solvent-free deposition of reagents onto paper-based microfluidic devices. The pencils are portable, easy to use, extend the shelf-life of reagents, and offer a platform for customizing diagnostic devices at the point of care. In this work, reagent pencils were characterized by measuring the wear resistance of pencil cores made from polyethylene glycols (PEGs) with different molecular weights and incorporating various concentrations of three different reagents using a standard pin abrasion test, as well as by measuring the efficiency of reagent delivery from the pencils to the test zones of paper-based microfluidic devices using absorption spectroscopy and …

Paper Microzone Plates As Analytical Tools For Studying Enzyme Stability: A Case Study On The Stabilization Of Horseradish Peroxidase Using Trehalose And Su-8 Epoxy Novolac Resin, Kirsten A. Ganaja, Cory Chaplan, Jingyi Zhang, Nathaniel W. Martinez, Andres W. Martinez

Chemistry and Biochemistry

Paper microzone plates in combination with a noncontact liquid handling robot were demonstrated as tools for studying the stability of enzymes stored on paper. The effect of trehalose and SU-8 epoxy novolac resin (SU-8) on the stability of horseradish peroxidase (HRP) was studied in both a short-term experiment, where the activity of various concentrations of HRP dried on paper were measured after 1 h, and a long-term experiment, where the activity of a single concentration of HRP dried and stored on paper was monitored for 61 days. SU-8 was found to stabilize HRP up to 35 times more than trehalose …

Paper-Based Diagnostic Devices, Spencer A. Schultz, Isabelle C. Noxon, Tyler A. Sisley, Andres W. Martinez

Chemistry and Biochemistry

This chapter will provide an overview of existing diagnostic devices made primarily out of paper and then focus on paper-based microfluidic devices, the next generation of paper-based diagnostic devices that promises to extend the use of paper as a material for fabricating diagnostic devices well into the future.

Chapter Contents:

• 2.1 Introduction
• 2.2 Current paper-based diagnostic devices
• 2.2.1 Dipstick devices
• 2.2.2 Lateral-flow devices
• 2.2.2.1 Vertical-flow devices
• 2.2.3 Paper-based arrays
• 2.3 Paper-based microfluidic devices
• 2.3.1 Fabrication of paper-based microfluidic devices
• 2.3.2 Applications of paper-based microfluidic devices
• 2.4 Conclusions
• References

Phthalate Plasticizers Covalently Linked To Pvc Via Copper-Free Or Copper Catalyzed Axide-Alkyne Cycloadditions, Aruna Earla, Li Longbo, Philip Costanzo, Rebecca Braslau

Chemistry and Biochemistry

Plasticization of PVC was carried out by covalently linking phthalate derivatives via copper-free (thermal) or copper catalyzed azide-alkyne cycloadditions. Di(2-ethylhexyl) phthalate derivatives (DEHP-ether and DEHP-ester) were synthesized and appended to PVC at two different densities. The glass transition temperatures of the modified PVC decreased with increasing content of plasticizer. PVC-DEHP-ether gave lower glass transition temperatures than PVC-DEHP-ester, reflecting the enhanced flexibility of the ether versus ester linker.

An Examination Of Student Outcomes In Studio Chemistry, Alan L. Kiste, Gregory E. Scott, Jesse Paul Bukenberger, Miles Markmann, Jennifer Moore

Chemistry and Biochemistry

Twenty years ago, a major curriculum revision at a large, comprehensive university in the Western United States led to the implementation of an integrated lecture/laboratory (studio) experience for our engineering students taking general chemistry. Based on these twenty years of experience, construction of four purpose-built studio classrooms to house the majority of the remaining general chemistry courses was completed in 2013. A detailed study of the effects of the entire ecology of the studio experience on student success was initiated at that time. Data from content knowledge pre- and post-tests, learning attitudes surveys, and student course evaluations show positive effects …

Atomic Tiles: Manipulative Resources For Exploring Bonding And Molecular Structure, Alan L. Kiste, Rebecca G. Hooper, Gregory E. Scott, Seth Bush

Chemistry and Biochemistry

A simple manipulative resource, Atomic Tiles, is described for scaffolding the learning of Lewis structures without using algorithmic, rule-based methods of drawing. Students use Atomic Tiles to (1) create models of bonding that lead to drawing Lewis structures, (2) use the structures they create to infer patterns required for rational structures and common organic functional groups, (3) translate between Lewis structures and molecular models, and (4) use molecular models to identify isomers.

Comparative Analysis Of In Situ Fibronectin Using Tof-Sims, Spi-Ms, And Dropdesi-Ms In A Microfluidic Reactor, Shannon Fasing, Xiao-Ying Yu, Juan Yao, Jiachao Yu

STAR Program Research Presentations

Fibronectin is an important biomolecule due to its role in cell differentiation, growth, kinesis, and adhesion. Such biological responses are mediated through membrane recognition and signaling; where fibronectin is found. Studying the outer molecular surface of fibronectin allows deeper insight into the microbiological reactions that occur during these processes. In situ mass spectrometry analysis in aqueous solution accurately represents fibronectin’s chemical components, made possible by a vacuum compatible microfluidic reactor, SALVI (System for Analysis at the Liquid Vacuum Interface). SALVI was paired with the analytical tools: time-of-flight secondary ion mass spectrometer (ToF-SIMS), single photon ionization mass spectrometer (SPI-MS) and drop …

Production And Harvest Of Microalgae In Wastewater Raceways With Resource Recycling, Alexander Colin Roberts

Master's Theses

Microalgae can be grown on municipal wastewater media to both treat the wastewater and produce feedstock for algae biofuel production. However the reliability of treatment must be demonstrated, as well as high areal algae productivity on recycled wastewater media and efficient sedimentation harvesting. This processes was studied at pilot scale in the present research.

A pilot facility was operated with nine CO₂-supplemented raceway ponds, each with a 33-m² surface area and a 0.3-m depth, continuously from March 6, 2013 through September 24, 2014. The ponds were operated as three sets of triplicates with two sets continuously fed …

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.

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

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 …

Paper-Based Standard Addition Assays, Cory A. Chaplan, Haydn T. Mitchell, Andres W. Martinez

Chemistry and Biochemistry

Standard addition assays conducted on paper-based microfluidic devices are introduced as an alternative to external standards for calibrating quantitative tests. To demonstrate this technique, a colorimetric, paper-based, standard addition assay was optimized for the determination of glucose concentrations in the range of 0 to 5 mM. Comparable results were obtained from the assay via digital image colorimetry under three different lighting conditions.

Synthesis And Evaluation Of Thermally-Responsive Coatings Based Upon Diels–Alder Chemistry And Renewable Materials, Dahlia N. Amato, Gregory A. Strange, John P. Swanson, Anton D. Chavez, Suzanne E. Roy, Kim L. Varney, Craig A. Machado, Douglas V. Amato, Philip Costanzo

Chemistry and Biochemistry

A soybean based coating with thermally responsive Diels–Alder linkages has been prepared following an automotive 2-component formulation. The resulting coatings displayed the capability to be healed following physical deformation by a thermal stimulus, and such a material has significant potential for end users. Various curing agents were employed, and resulted in variation of scratch resistance and re-healablity. Different thermally responsive soybean resins were synthesized to have varying amounts reversible and nonreversible linkages when incorporated into the coating. Additionally, different isocyanates were added at differing ratios of NCO:OH in search of the optimum coating. It was found through the analysis of …

Paper And Toner Three-Dimensional Fluidic Devices: Programming Fluid Flow To Improve Point-Of-Care Diagnostics, Kevin M. Schilling, Daisy Jauregui, Andres W. Martinez

Chemistry and Biochemistry

We present a new method for fabricating three-dimensional paper-based fluidic devices that uses toner as a thermal adhesive to bond multiple layers of patterned paper together. The fabrication process is rapid, involves minimal equipment (a laser printer and a laminator) and produces complex channel networks with dimensions down to 1 mm. The devices can run multiple diagnostic assays on one or more samples simultaneously, can incorporate positive and negative controls and can be programmed to display the results of the assays in a variety of patterns. The patterns of the results can encode information, which could be used to identify …

Optimizing Electrode Design For Microbial Fuel Cells Used For Wastewater Treatment, Lindsay Nichols, John A. Hogan

STAR Program Research Presentations

Microbial fuel cells (MFC) utilize bacteria to generate an electrical current that can be used in the decomposition of sludge and human urine. In a MFC there is an anode (for oxidation of organic compounds), cathode (reduction of oxygen or carbon dioxide), and a proton exchange membrane (PEM, allows protons to migrate); reduction-oxidation reactions between the anode and cathode produce a measurable current. Bacteria that are found in sludge can be used to produce electrons in a voltaic cell, but optimizing conditions for harnessing the energy is crucial to making a MFC efficient. Research has shown that the ratios of …

Using Stable Isotope Analysis Of Zooplankton To Document Trophic And Biogeochemical Changes In The San Francisco Estuary, Steven C. Westbrook, Julien Moderan

STAR Program Research Presentations

Zooplankton represent a vital link between phytoplankton and fish, like the endangered Delta Smelt. Human interferences (nitrates from waste water, flow alteration, invasive species introduction…) have altered the structure of the San Francisco Estuary (SFE) ecosystem. We use stable isotope analysis to improve our knowledge of the planktonic food web in the SFE and gain insights into its evolution over the past decades. We use the ratios of certain isotopes (Nitrogen, Carbon, Sulfur, etc.) in different species of zooplankton to tell us what it is feeding on as well as the trophic level it feeds in. My research focused on …

Correction To Fully Enclosed Microfluidic Paper-Based Analytical Devices, Kevin M. Schilling, Anna L. Lepore, Jason A. Kurian, Andres W. Martinez

Chemistry and Biochemistry

There is an error in the units of the concentrations of potassium iodide and trehalose described in the experimental details on page 1581. The correct concentrations are 0.6 M potassium iodide and 0.3 M trehalose.

Fully Enclosed Microfluidic Paper-Based Analytical Devices, Kevin M. Schilling, Anna L. Lepore, Jason A. Kurian, Andres W. Martinez

Chemistry and Biochemistry

This article introduces fully enclosed microfluidic paper-based analytical devices (microPADs) fabricated by printing toner on the top and bottom of the devices using a laser printer. Enclosing paper-based microfluidic channels protects the channels from contamination, contains and protects reagents stored on the device, contains fluids within the channels so that microPADs can be handled and operated more easily, and reduces evaporation of solutions from the channels. These benefits extend the capabilities of microPADs for applications as low-cost point-of-care diagnostic devices.

Β-Casein–Phospholipid Monolayers As Model Systems To Understand Lipid–Protein Interactions In The Milk Fat Globule Membrane, Sophie Gallier, Derek E. Gragson, Rafael Jiménez-Flores, David W. Everett

Chemistry and Biochemistry

Phospholipid–protein monolayer films were studied as model systems to mimic the structure of the native bovine milk fat globule membrane (MFGM) and to understand lipid–protein interactions at the surface of the globule. Phospholipids extracted from bovine raw milk, raw cream, processed milk and buttermilk powder were spread onto the air–water interface of a Langmuir trough, β-casein was then added to the sub-phase, and Langmuir–Blodgett films were studied by epifluorescence microscopy and atomic force microscopy. In all films, β-casein was responsible for clustering of the sphingomyelin- and cholesterol-rich microdomains into larger platforms. This suggests that the same phenomenon may happen at …

Thermal-Initiated Hydroxyethyl Methacrylate Functionalization Of Multiwalled Carbon Nanotubes, Greg Curtzwiler, Philip Costanzo, Ray Fernando, Jeffrey E. Danes, Keith Vorst

Chemistry and Biochemistry

Multiwalled-carbon nanotubes (MWCNTs) were functionalized via thermoinitiated free radical polymerization of 2-hydroxyethyl methacrylate (HEMA) using benzoyl peroxide. Tip sonication was used during the polymerization reaction to separate agglomerated nanotubes. The functionalization was confirmed by control experiments and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). Differential scanning calorimetry indicated that the addition of poly(HEMA)-MWCNTs to a two-component polyurethane coating will have little effect on the glass transition temperature of the coating. The poly(HEMA)-functionalized MWCNTs formed large colloidal structures of highly dispersed nanotubes in both the nonsheared and sheared coatings as determined by atomic force microscopy. This study determined a quick …

Direct Imaging Of Two-State Dynamics On The Amorphous Silicon Surface, S. Ashtekar, Gregory E. Scott, J. Lyding, M. Gruebele

Chemistry and Biochemistry

Amorphous silicon is an important material, amidst a debate whether or not it is a glass. We produce amorphous Si surfaces by ion bombardment and vapor growth, and image discrete Si clusters which hop by two-state dynamics at 295 K. Independent of surface preparation, these clusters have an average diameter of ~5 atoms. Given prior results for metallic glasses, we suggest that this cluster size is a universal feature. The hopping activation free energy of 0.93 ± 0.15 eV is rather small, in agreement with a previously untested surface glass model. Hydrogenation quenches the two-state dynamics, apparently by increasing surface …

Better Biomolecule Thermodynamics From Kinetics, Kiran Girdhar, Gregory Scott, Yann R. Chemla, Martin Gruebele

Chemistry and Biochemistry

Protein stability is measured by denaturation: When solvent conditions are changed (e.g., temperature, denaturant concentration, or pH) the protein population switches between thermodynamic states. The resulting denaturation curves have baselines. If the baselines are steep, nonlinear, or incomplete, it becomes difficult to characterize protein denaturation. Baselines arise because the chromophore probing denaturation is sensitive to solvent conditions, or because the thermodynamic states evolve structurally when solvent conditions are changed, or because the barriers are very low (downhill folding). Kinetics can largely eliminate such baselines: Relaxation of chromophores, or within thermodynamic states, is much faster than the transition over activation …

Microfluidic Paper-Based Analytical Devices: From Pocket To Paper-Based Elisa, Andres W. Martinez

Chemistry and Biochemistry

Microfluidic paper-based analytical devices (microPADs) began as a simple idea with an ambitious goal. The idea was to make microfluidic devices out of paper instead of plastic or glass. The goal was to develop low-cost and portable paper-based diagnostic devices to improve healthcare in developing countries. Over the past 6 years, many developments have been made in the emerging field of paper-based microfluidic devices. Reviewing the development of these devices in the Whitesides group at Harvard University (Cambridge, MA, USA) can provide some insight into the future of the field and encourage scientists from a variety of backgrounds to contribute …

Dual Inhibition Of Sodium-Mediated Proton And Calcium Efflux Triggers Non-Apoptotic Cell Death In Malignant Gliomas, William Harley, Candace Floyd, Tamara Dunn, Xiao-Dong Zhang, Tsung-Yu Chen, Manu Hegde, Hasan Palandoken, Michael H. Nantz, Leonardo Leon, K.L. Carraway Iii, Bruce Lyeth, Fredric A. Gorin

Chemistry and Biochemistry

Malignant glioma cells maintain an elevated intracellular pH (pH_i) within hypoxic–ischemic tumormicroenvironments through persistent activation of sodium–proton transport (McLean et al., 2000). Amiloride has been reported to selectively kill human malignant glioma cell lines but not primary astrocytes (Hegde et al., 2004). While amiloride reduces pH_i of malignant gliomas by inhibiting isoform 1 of sodium–proton exchange (NHE1), direct acidification was shown to be cytostatic rather than cytotoxic. At cytotoxic concentrations, amiloride has multiple drug targets including inhibition of NHE1 and sodium–calciumexchange. Amiloride's glioma cytotoxicity can be explained, at least in part, by dual inhibition of NHE1 and …

Solving The Low Dimensional Smoluchowski Equation With A Singular Value Basis Set, Gregory E. Scott, Martin Gruebele

Chemistry and Biochemistry

Reaction kinetics on free energy surfaces with small activation barriers can be computed directly with the Smoluchowski equation. The procedure is computationally expensive even in a few dimensions. We present a propagation method that considerably reduces computational time for a particular class of problems: when the free energy surface suddenly switches by a small amount, and the probability distribution relaxes to a new equilibrium value. This case describes relaxation experiments. To achieve efficient solution, we expand the density matrix in a basis set obtained by singular value decomposition of equilibrium density matrices. Grid size during propagation is reduced from (100–1000) …

Novel Polymer Coupling Chemistry Based Upon Latent Cysteine-Like Residues And Thiazolidine Chemistry, Jospeh S. Carlson, Megan R. Hill, Taiga Young, Philip Costanzo

Chemistry and Biochemistry

Chain end functional polymers were prepared via reversible addition–fragmentation transfer (RAFT) polymerization techniques that were further chain extended with acrylonitrile. Under reducing conditions, latent cysteine-like residues were exposed at the chain ends. A variety of reduction conditions were explored and base polymers were then tethered together via thiazolidine chemistry.