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Adhesion And Interfacial Fracture Toughness Between Hard And Soft Materials, Nima Rahbar, Kurt Wolf, Argjenta Orana, Roy Fennimore, Zong Zong, Juan Meng, George Papandreou, Cynthia Maryanoff, Wole Soboyejo

Nima Rahbar

This paper presents the results of a combined experimental and theoretical study of adhesion between hard and soft layers that are relevant to medical devices such as drug-eluting stents and semiconductor applications. Brazil disk specimens were used to measure the interfacial fracture energies between model parylene C and 316L stainless steel over a wide range of mode mixities. The trends in the overall fracture energies are predicted using a combination of adhesion theories and fracture mechanics concepts. The measured interfacial fracture energies are shown to be in good agreement with the predictions.

Potential Driven Deposition Of Poly(Diallyldimethylammonium Chloride) Onto The Surface Of 3-Mercaptopropionic Acid Monolayers Assembled On Gold, Wesley Sanders, Mark Anderson

Mark R. Anderson

Electrochemical impedance spectroscopy (EIS) and quartz crystal microbalance (QCM) measurements are used to examine the ability of applied potential to drive the ionic self-assembly of poly(diallyldimethylammonium) chloride (PDDA) onto a substrate modified with a monolayer of 3-mercaptopropionic acid (3-MPA). The potential of zero charge (PZC) of the gold electrode modified with a monolayer of 3-MPA was found by differential capacitance measurements to be −0.12 (±0.01) V versus Ag−AgCl. Changing the substrate potential to values positive (−0.01 V vs Ag−AgCl) of the PZC induces interfacial conditions that are favorable for the electrostatic deposition of cationic polymers onto the surface of 3-MPA …

Sequence Specific And High Affinity Recognition Of 5′-Acgcgt-3′ By Rationally Designed Pyrrole-Imidazole H-Pin Polyamides: Thermodynamic And Structural Studies., Hilary Mackay, Toni Brown, Peter Uthe, Laura Westrate, Alan Sielaff, Justin Jones, James Lajiness, Jerome Kluza, Caroline O'Hare, Binh Nguyen, Zach Davis, Chrystal Bruce, W. Wilson, John Hartley, Moses Lee

Chrystal D. Bruce

Imidazole (Im) and Pyrrole (Py)-containing polyamides that can form stacked dimers can be programmed to target specific sequences in the minor groove of DNA and control gene expression. Even though various designs of polyamides have been thoroughly investigated for DNA sequence recognition, the use of H-pin polyamides (covalently cross-linked polyamides) has not received as much attention. Therefore, experiments were designed to systematically investigate the DNA recognition properties of two symmetrical H-pin polyamides composed of PyImPyIm (5) or f-ImPyIm (3e, f=formamido) tethered with an ethylene glycol linker. These compounds were created to recognize the cognate 5′-ACGCGT-3′ through an overlapped and staggered …

Characterization Of Carboxylic Acid-Terminated Self-Assembled Monolayers By Electrochemical Impedance Spectroscopy And Scanning Electrochemical Microscopy, Wesley Sanders, Ricardo Vargas, Mark Anderson

Mark R. Anderson

Electrochemical impedance spectroscopy (EIS) and scanning electrochemical microscopy (SECM) are used to monitor changes in the ionization of monolayers of 11-mercaptoundecanoic acid. When using an anionic redox probe, Fe(CN)6−4, the charge-transfer resistance of the 11-mercaptoundecanoic acid monolayer-modified interface increases in a sigmoidal fashion as the solution is made basic. The opposite effect is observed when using a cationic redox probe. The inflection points of these two titration curves, however, differ when using the different redox probes. This result is taken as being characteristic of the influence that applied potential has on the ionization of the monolayer. The role of substrate …

Modifying The N-Terminus Of Polyamides: Pyimpyim Has Improved Sequence Specificity Over F-Impyim, Toni Brown, Hilary Mackay, Mark Turlington, Arden Sutterfield, Traci Smith, Alan Sielaff, Laura Westrate, Chrystal Bruce, Jerome Kluza, Caroline O'Hare, Binh Nguyen, W. Wilson, John Hartley, Moses Lee

Chrystal D. Bruce

Seven N-terminus modified derivatives of a previously published minor-groove binding polyamide (f-ImPyIm, 1) were synthesized and the biochemical and biophysical chemistry evaluated. These compounds were synthesized with the aim of attaining a higher level of sequence selectivity over f-ImPyIm (1), a previously published strong minor-groove binder. Two compounds possessing a furan or a benzofuran moiety at the N-terminus showed a footprint of 0.5μM at the cognate ACGCGT site (determined by DNase I footprinting); however, the specificity of these compounds was not improved. In contrast, PyImPyIm (4) produced a footprint of 0.5μM but showed a superior specificity using the same technique. …

Simultaneous Determination Of Glucose And L‐Glutamate Using A Capillary Enzyme Reactor With Electrochemical Detection, Stephanie Hooper, Mark Anderson

Mark R. Anderson

An electrophoresis capillary that incorporates two enzymes for the simultaneous determination of glucose and l-glutamate is described. The enzymes deposited along the separation capillary walls react with their respective substrate as they are separated during the electrophoresis to produce hydrogen peroxide that is detected by amperometry as the hydrogen peroxide zone emerges from the end of the capillary. Even though both enzyme reactions produce a common product, hydrogen peroxide, the hydrogen peroxide produced by each enzyme reaction stays in narrow zones that migrate the length of the capillary at different rates. The rate of migration for the individual H2O2 zones …

The Development Of Novel Therapeutics For Sickle-Cell Disease, Brian Brennan, Sara Costello, '10, Steven Sturlis, '10

Brian B. Brennan

No abstract provided.

The Expression Of Recombinant Hemoglobin In Escherichia Coli, Brian Brennan, Christopher Miedema, '10, Evan Mason, '10

Brian B. Brennan

No abstract provided.

Selective Formation Of A Symmetric Sc3n@C78 Bisadduct:  Adduct Docking Controlled By An Internal Trimetallic Nitride Cluster, Ting Cai, Liaosa Xu, Chunying Shu, Hunter Champion, Jonathan Reid, Clemins Anklin, Mark Anderson, Harry Gibson, Harry Dorn

Mark R. Anderson

In this paper we report a regioselective Bingel−Hirsch reaction of Sc3N@C78 yielding a single mono- and a dominate bis-ethyl malonate derivative for the first time. The Cs-symmetric monoadduct 1 and C2v-symmetric bisadduct 2 were isolated by HPLC and characterized by MS, UV−vis, and NMR spectroscopy. The symmetric bisadduct 2 clearly demonstrate the remarkable regioselectivity control exerted by the encapsulated Sc3N cluster. We have employed a LUMO electron density surface computational approach to predict multiadduct docking sites on the ellipsoidal fullerene cage surface.

'Partial Derivatives: Are You Kidding?': Teaching Thermodynamics Using Virtual Substance, Chrystal Bruce, Carribeth Bliem, John Papanikolas

Chrystal D. Bruce

No abstract provided.

Highly Fluorous Bidentate Phosphines, Brad Berven, George Koutsantonis

Brad Berven

The reaction of tetrachlorodiphosphines [Cl2P(CH2)nPCl2; n = 2-4] with fluorous aromatic precursors 4-bromo(perfluorohexyl)benzene and 4-(perfluorohexyl)phenol gave a series of fluorous-tagged diphosphines [(p-C6F13C6H4)2P(CH2)nP(C6H4C6F13-p)2; n = 2-4] and a new diphosphonite [(p-C6F13C6H4O)2P(CH2)3P(OC6H4C6F13-p)2]. The improved synthesis of 1,3-bis(dichlorophosphino)propane (dcpp), involved the facile chlorination of the corresponding primary phosphine with triphosgene. Fluorinated diimines RN=C(CH3)C(CH3)=NR, where R = p-C6H4C6F13 or p-C6H4C8F17 have also been prepared, and were found to be air-stable alternatives to the highly air-sensitive phosphorus-containing ligands. All compounds were characterised by a variety of techniques including NMR, IR, MS and microanalysis. The successful reduction of the phosphine-oxides [(p-C6F13C6H4)2P(O)(CH2)nP(O)(C6H4C6F13-p)2; n = 2,3] with phenylsilane …

Environmentally Friendly Organic Synthesis Using Bismuth Compounds. Bismuth Trifluoromethanesulfonate-Catalyzed Allylation Of Dioxolanes, Ram Mohan, Matthew Spaffpord, James Christensen, Matthew Huddle, Joshua Lacey

Ram S. Mohan

A bismuth trifluoromethanesulfonate (triflate)-catalyzed (2.0 mol-%) multicomponent reaction involving the allylation of dioxolanes followed by in situ derivatization with anhydrides to generate highly functionalized esters has been developed under solvent-free conditions. Most reagents used to date for allylation of dioxolanes are highly corrosive and are often required in stoichiometric amounts. In contrast, the use of a relatively non-toxic and non-corrosive bismuth(iii)-based catalyst makes this methodology especially attractive for scale-up.

Application Of A Square‐Wave Potential Program For Time‐Dependent Amperometric Detection In Capillary Electrophoresis, Stephanie Hooper, David Roach, Mark Anderson

Mark R. Anderson

Use of a square-wave potential program for time-dependent amperometric detection of analyte zones in capillary electrophoresis (CE) is described. Electrochemical detection for CE requires that the separation field be isolated from that of the electrochemical detection. This is generally done by physically separating the CE separation field from that of the detection. By applying a time variant potential program to the detection electrode, the detector current has a time dependence that can be used to help isolate the electrochemical detection current from that of the separation. When using a 20 μm inner-diameter capillary, we find that a square-wave potential program …

Intermolecular Forces And The Glass Transition, Randall W. Hall, Peter G. Wolynes

Randall W. Hall