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Full-Text Articles in Physical Sciences and Mathematics

Replacing −Ch2ch2– With −Conh– Does Not Significantly Change Rates Of Charge Transport Through Agts-Sam//Ga2o3/Egain Junctions, Martin M. Thuo, William F. Reus, Felice C. Simeone, Choongik Kim, Michael D. Schulz, Hyo Jae Yoon, George M. Whitesides Jun 2012

Replacing −Ch2ch2– With −Conh– Does Not Significantly Change Rates Of Charge Transport Through Agts-Sam//Ga2o3/Egain Junctions, Martin M. Thuo, William F. Reus, Felice C. Simeone, Choongik Kim, Michael D. Schulz, Hyo Jae Yoon, George M. Whitesides

Martin M. Thuo

This paper describes physical-organic studies of charge transport by tunneling through self-assembled monolayers (SAMs), based on systematic variations of the structure of the molecules constituting the SAM. Replacing a −CH2CH2– group with a −CONH– group changes the dipole moment and polarizability of a portion of the molecule and has, in principle, the potential to change the rate of charge transport through the SAM. In practice, this substitution produces no significant change in the rate of charge transport across junctions of the structure AgTS-S(CH2)mX(CH2)nH//Ga2O3/EGaIn (TS = template stripped, X = −CH2CH2– or −CONH–, and EGaIn = eutectic alloy of gallium and …


A Reference-Free Algorithm For Computational Normalization Of Shotgun Sequencing Data, C. Titus Brown, Adina Howe, Qingpeng Zhang, Alexis B. Pyrkosz, Timothy H. Brom May 2012

A Reference-Free Algorithm For Computational Normalization Of Shotgun Sequencing Data, C. Titus Brown, Adina Howe, Qingpeng Zhang, Alexis B. Pyrkosz, Timothy H. Brom

Adina Howe

Deep shotgun sequencing and analysis of genomes, transcriptomes, amplified single-cell genomes, and metagenomes has enabled investigation of a wide range of organisms and ecosystems. However, sampling variation in short-read data sets and high sequencing error rates of modern sequencers present many new computational challenges in data interpretation. These challenges have led to the development of new classes of mapping tools and {\em de novo} assemblers. These algorithms are challenged by the continued improvement in sequencing throughput. We here describe digital normalization, a single-pass computational algorithm that systematizes coverage in shotgun sequencing data sets, thereby decreasing sampling variation, discarding redundant data, …


Measuring Markers Of Liver Function Using A Micropatterned Paper Device Designed For Blood From A Fingerstick, Sarah J. Vella, Patrick Beattie, Rebecca Cademartiri, Anna Laromaine, Andres W. Martinez, Scott T. Phillips, Katherine A. Mirica, George M. Whitesides Mar 2012

Measuring Markers Of Liver Function Using A Micropatterned Paper Device Designed For Blood From A Fingerstick, Sarah J. Vella, Patrick Beattie, Rebecca Cademartiri, Anna Laromaine, Andres W. Martinez, Scott T. Phillips, Katherine A. Mirica, George M. Whitesides

Rebecca Cademartiri

This paper describes a paper-based microfluidic device that measures two enzymatic markers of liver function (alkaline phosphatase, ALP, and aspartate aminotransferase, AST) and total serum protein. A device consists of four components: (i) a top plastic sheet, (ii) a filter membrane, (iii) a patterned paper chip containing the reagents necessary for analysis, and (iv) a bottom plastic sheet. The device performs both the sample preparation (separating blood plasma from erythrocytes) and the assays; it also enables both qualitative and quantitative analysis of data. The data obtained from the paper-microfluidic devices show standard deviations in calibration runs and “spiked” standards that …


Statistical Tools For Analyzing Measurements Of Charge Transport, William F. Reus, Christian A. Nijhuis, Jabulani R. Barber, Martin M. Thuo, Simon Tricard, George M. Whitesides Feb 2012

Statistical Tools For Analyzing Measurements Of Charge Transport, William F. Reus, Christian A. Nijhuis, Jabulani R. Barber, Martin M. Thuo, Simon Tricard, George M. Whitesides

Martin M. Thuo

This paper applies statistical methods to analyze the large, noisy data sets produced in measurements of tunneling current density (J) through self-assembled monolayers (SAMs) in large-area junctions. It describes and compares the accuracy and precision of procedures for summarizing data for individual SAMs, for comparing two or more SAMs, and for determining the parameters of the Simmons model (β and J0). For data that contain significant numbers of outliers (i.e., most measurements of charge transport), commonly used statistical techniques—e.g., summarizing data with arithmetic mean and standard deviation and fitting data using a linear, least-squares algorithm—are prone to large errors. The …


Electrical Resistance Of Agts–S(Ch2)N−1ch3//Ga2o3/Egain Tunneling Junctions, Ludovico Cademartiri, Martin M. Thuo, Christian A. Nijhuis, William F. Reus, Simon Tricard, Jubulani R. Barber, Rana N.S. Sodhi, Peter Brodersen, Choongik Kim, Ryan C. Chiechi, George M. Whitesides Feb 2012

Electrical Resistance Of Agts–S(Ch2)N−1ch3//Ga2o3/Egain Tunneling Junctions, Ludovico Cademartiri, Martin M. Thuo, Christian A. Nijhuis, William F. Reus, Simon Tricard, Jubulani R. Barber, Rana N.S. Sodhi, Peter Brodersen, Choongik Kim, Ryan C. Chiechi, George M. Whitesides

Martin M. Thuo

Tunneling junctions having the structure AgTS–S(CH2)n−1CH3//Ga2O3/EGaIn allow physical–organic studies of charge transport across self-assembled monolayers (SAMs). In ambient conditions, the surface of the liquid metal electrode (EGaIn, 75.5 wt % Ga, 24.5 wt % In, mp 15.7 °C) oxidizes and adsorbs―like other high-energy surfaces―adventitious contaminants. The interface between the EGaIn and the SAM thus includes a film of metal oxide, and probably also organic material adsorbed on this film; this interface will influence the properties and operation of the junctions. A combination of structural, chemical, and electrical characterizations leads to four conclusions about AgTS–S(CH2)n−1CH3//Ga2O3/EGaIn junctions. (i) The oxide is ∼0.7 …


Bacterial Isolation By Lectin-Modified Microengines, Susana Campuzano, Jahir Orozco, Daniel Kagan, Maria Guix, Wei Gao, Sirilak Sattayasamitsathit, Jonathan C. Claussen, Arben Merkoci, Joseph Wang Jan 2012

Bacterial Isolation By Lectin-Modified Microengines, Susana Campuzano, Jahir Orozco, Daniel Kagan, Maria Guix, Wei Gao, Sirilak Sattayasamitsathit, Jonathan C. Claussen, Arben Merkoci, Joseph Wang

Jonathan C. Claussen

New template-based self-propelled gold/nickel/polyaniline/platinum (Au/Ni/PANI/Pt) microtubular engines, functionalized with the Concanavalin A (ConA) lectin bioreceptor, are shown to be extremely useful for the rapid, real-time isolation of Escherichia coli (E. coli) bacteria from fuel-enhanced environmental, food, and clinical samples. These multifunctional microtube engines combine the selective capture of E. coli with the uptake of polymeric drug-carrier particles to provide an attractive motion-based theranostics strategy. Triggered release of the captured bacteria is demonstrated by movement through a low-pH glycine-based dissociation solution. The smaller size of the new polymer-metal microengines offers convenient, direct, and label-free optical visualization of the captured bacteria and …


Mox/Cnts Hetero-Structures For Gas Sensing Applications: Role Of Cnts Defects, G. Neri, S. G. Leonardi, N. Donato, C. Marichy, Jean-Philippe Tessonnier, M.-G. Willinger, Kyeong-Hwan Lee, N. Pinna Jan 2012

Mox/Cnts Hetero-Structures For Gas Sensing Applications: Role Of Cnts Defects, G. Neri, S. G. Leonardi, N. Donato, C. Marichy, Jean-Philippe Tessonnier, M.-G. Willinger, Kyeong-Hwan Lee, N. Pinna

Jean-Philippe Tessonnier

The preparation, characterization and sensing properties of CNT composites with a thin metal oxide (MOx) surface layer is presented. Atomic layer deposition (ALD) was applied for the coating of the inner and outer CNTs walls with thin films of ZnO and SnO2 of precisely controlled thicknesses. Differently treated CNTs with different degree of surface functionalization were used as support for the oxide films. The sensing properties of the obtained composite materials towards NO2 were investigated and related to the morphological and microstructural characteristics of both the coating and support. SnO2-based composites on CNTs treated at 700 °C show enhanced performance …


Materials For Diabetes Therapeutics, Kaitlin M. Bratlie, Roger L. York, Michael A. Invernale, Robert Langer, Daniel G. Anderson Jan 2012

Materials For Diabetes Therapeutics, Kaitlin M. Bratlie, Roger L. York, Michael A. Invernale, Robert Langer, Daniel G. Anderson

Kaitlin M. Bratlie

This review is focused on the materials and methods used to fabricate closedloop systems for type 1 diabetes therapy. Herein, we give a brief overview of current methods used for patient care and discuss two types of possible treatments and the materials used for these therapies-(i) artificial pancreases, comprised of insulin producing cells embedded in a polymeric biomaterial, and (ii) totally synthetic pancreases formulated by integrating continuous glucose monitors with controlled insulin release through degradable polymers and glucose-responsive polymer systems. Both the artificial and the completely synthetic pancreas have two major design requirements: the device must be both biocompatible and …


Overview Of Fuel Ethanol Production And Distillers Grains, Kurt A. Rosentrater Jan 2012

Overview Of Fuel Ethanol Production And Distillers Grains, Kurt A. Rosentrater

Kurt A. Rosentrater

Modern societies face many challenges, including growing populations, increased demands for food, clothing, housing, consumer goods, and the concomitant raw materials required to produce all of these. Additionally, there is a growing need for energy, which is most easily met by use of fossil fuels (e.g., coal, natural gas, and petroleum). In 2008, the overall U.S. demand for energy was 99.3 x 1015 Btu (1.05 x 1014 MJ); 84% of this was supplied by fossil sources (U.S. EIA, 2009). Transportation fuels accounted for 28% of all energy consumed during this time, and nearly 97% of this came from fossil sources. …


Manufacturing Of Fuel Ethanol And Distillers Grains—Current And Evolving Processes, Kurt A. Rosentrater, Klein Ileleji, David B. Johnson Jan 2012

Manufacturing Of Fuel Ethanol And Distillers Grains—Current And Evolving Processes, Kurt A. Rosentrater, Klein Ileleji, David B. Johnson

Kurt A. Rosentrater

Before examining all of the different possible uses of distillers dried grains with solubles (DDGS), a discussion regarding ethanol and DDGS production methods is warranted. This chapter will cover current production processes and some of the new practices that have been developed and are being adopted at plants, including front-end fractionation and back-end fractionation. Additionally, standard coproduct definitions will be discussed, as they govern the marketing and sales of these materials.


Labeling And Monitoring The Distribution Of Anchoring Sites On Functionalized Cnts By Atomic Layer Deposition, Catherine Marichy, Jean-Philippe Tessonnier, Marta C. Ferro, Kyeong-Hwan Lee, Robert Schlogl, Nicola Pinna, Marc-Georg Willinger Jan 2012

Labeling And Monitoring The Distribution Of Anchoring Sites On Functionalized Cnts By Atomic Layer Deposition, Catherine Marichy, Jean-Philippe Tessonnier, Marta C. Ferro, Kyeong-Hwan Lee, Robert Schlogl, Nicola Pinna, Marc-Georg Willinger

Jean-Philippe Tessonnier

The chemical inertness of graphite and, in the case of tubes, of rolled up few layer graphene sheets, requires some degree of "defect engineering" for the fabrication of carbon based heterostructured materials. It is shown that atomic layer deposition provides a means to specifically label anchoring sites and can be used to characterize the surface functionality of differently treated carbon nanotubes. Direct observation of deposited titania by analytical transmission electron microscopy reveals the location and density of anchoring sites as well as structure related concentrations of functional groups on the surface of the tubes. Controlled functionalization of the tubes therefore …


Toward A Scientific Understanding Of Ddgs, Keshun Liu, Kurt A. Rosentrater Jan 2012

Toward A Scientific Understanding Of Ddgs, Keshun Liu, Kurt A. Rosentrater

Kurt A. Rosentrater

Recently, many people have asked what the fuel ethanol industry is going to do about the growing piles of nonfermented leftovers. Actually this question has been around for quite some time. As early as the 1940s, one report stated that "Grain distillers have developed equipment and an attractive market for their recovered grains" (Boruff, 1947), while another report described that "Distillers are recovering, drying, and marketing their destarched grain stillage as distillers dried grains and dried solubles" (Boruff, 1952). So it appears that a viable solution had already been developed as far back as the 1940s. And by the early …