isis poster session
program information / abstracts

Congratulations to our poster session winners, who have been awarded a $50 gift certificate to the UCI Bookstore!  See photos of winners and participants below!


Poster Session Award Recipients:

14.  Author(s)::  R. J. Lazarowich and P. Taborek (1);  N. V. Myung (2)
(1) Department of Physics and Astronomy, UC Irvine
(2) Department of Chemical and Environmental Engineering, U C Riverside    
   
TITLE::  FABRICATION OF HUMIDITY SENSORS USING POROUS ALUMINA    
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17.  Author(s)::  A. A. Shinde C. Jo J.P. You J. Choi R. Wu R. Ragan
Department of Physics and Astronomy / ChEMS, UC Irvine    
   
TITLE::  FABRICATION, OPTIMIZATION AND MODELING OF HIGHLY ORDERED ASSEMBLIES OF MONODISPERSE METALLIC NANOSTRUCTURE ARRAYS
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18.  Author(s):: I. Vlassiouk, Z. Siwy
Department of Physics and Astronomy, UC Irvine    
 
TITLE::  NANOFLUIDIC DIODE
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20.  Author(s)::  C. Xiang, M.A. Thompson,  A.G. Güell,  E.J. Menke, R. M. Penner
Department of Chemistry, U C Irvine    

TITLE::  LITHOGRAPHICALLY PATTERNED NANOWIRE ELECTRODEPOSITION
POSTER SESSION WINNERS

December 8, 2006

5:00 - 7:00 p.m.

Location:  1201 Natural Sciences II

ISIS (the Institute of Surface and Interface Science) is one of 16 Organized Research Units (ORUs) on the University of California, Irvine (UCI) campus. Through collaborative projects it brings together faculty and researchers in:

:: Chemistry
:: Physics
:: Developmental and Cell Biology
:: Chemical Engineering and Materials Science
:: INRF
:: Electrical Engineering and Computer Science

This poster session is informal in nature, and it provides an opportunity to learn about current ISIS member research projects.  This is also a social occasion for ISIS members to get together to interact - students, postdocs and other group members are especially welcome! 

Posters for the session can be composed of papers presented at recent conferences, or just a few figures interspersed with brief explanatory prose.

Please submit abstract and presentation using the ONLINE SUBMISSION FORM:

http://forms5.createforms.com/11061/form_3_1.html

If your abstract exceeds 250 characters, please forward it to Alison Lara:

laraa@uci.edu

For additional information, please contact:

Anne Taub (annetaub@uci.edu) or Diane Stathakis (destatha@uci.edu).

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Program Information  (updated 12-11-2006 10:00 a.m.)
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1
Author(s)::	M. G. Aggleton, J. C. Burton, D. A. Hook, P. Taborek, J. E. Rutledge, M. T. Dugger (email: maggleton@gmail.com)
Affiliation(s)::	Chemical & Material Physics, U C Irvine
Title::	Cryotribology in Micro and Macroscale Setups
Abstract::	An overview of current and recent cryo-tribological studies performed at UCI with support from NCSU and Sandia Nationa Laboratories.  We focus on two systems: a sliding block tribometer and a MEMS tribometer.  Measurements of static and kinetic friction are taken from room temperature to 4K.  This work is supported by Extreme Friction: MURI AFOSR # FA9550-04-1-0381.

2
Author(s)::	J. A. Abbondondola, K. Janda (email: jabbondo@uci.edu)
Affiliation(s)::	Chemical & Material Physics, U C Irvine
Title::	Hydrogen and Argon Uptake into a Propane Hydrate
Abstract::	It has been proposed that clathrate hydrates can be a possible storage medium for alternative fuels, such as hydrogen.  However, pure hydrogen clathrate requires extremely high pressure (220MPa) and low temperature (249K) for production, resulting in a costly hydrate to produce and use in commercial applications.  The sII natural gas hydrate is an alternative to a pure hydrogen clathrate.  The larger cavities are filled by a relatively large guest molecule (e.g., propane), the small cavities are available for hydrogen storage.  Our objective is to determine whether hydrogen diffuses into the sII propane hydrate at near-ambient conditions and quantify the uptake rate.  We investigated hydrogen and argon gas uptake into a propane hydrate and into ice grains at 0.68 MPa and 263 K.  The data showed that there is an average of 19 times more total gas uptake into the propane hydrate, as compared to the ice grain samples. A review of the physical processes involved in gas adsorption and absorption into a solid suggests that the dominant process involved in hydrate-uptake is bulk or lattice diffusion.  The ice grain-uptake is very small and saturates very quickly which is indicative of surface adsorption.  The propane hydrate occupancy yields for the total hydrogen and argon uptake were estimated at 1.3 % and 1.8 %; respectively.  The average argon initial hydrate-uptake rate is 8.7 x 10-6 Mol/g-hr, which is less than the average hydrogen initial hydrate-uptake rate of 2.7 x 10-4 Mol/g-hr.  Initially, the hydrogen uptake rate into a propane hydrate is faster than the argon hydrate-uptake rate, but this hydrogen uptake rate decreases within 10 minutes to near-equilibrium.  The argon hydrate-uptake rate does not reach equilibrium even at the end of a 90 hour experimental run.  This results in a total argon uptake into a propane hydrate which is larger than the hydrogen uptake over the long-time period.

3
Author(s)::	M. Bourg, R. M. Penner (email: mbourg@uci.edu)
Affiliation(s)::	Department of Chemistry, UC Irvine
Title::	Towards Nanowire-Based Thermocouples
Abstract::	The ability to accurately measure temperature on the same time scale as a thermal process under investigation is important in many industrial processes.  A thermocouple, which consists of a junction between two dissimilar metals, is most often the device used for such measurements.  As the thermal mass of the junction decreases, the response time decreases and the spatial resolution increases.  Therefore, junctions containing nanowires should lead to faster response times and increased spatial resolution.  In order to initally investigate this, we prepared nanowire-thin film (NWTF) junctions consisting of electrodeposited nanowires and an evaporated film.  These devices measure temperature accurately and reproducibly, and have a response time of 1.9ms.  For comparison, the response time of a 125μm type J thermocouple was 5.7ms.  To improve upon the enhancements shown by NWTF devices, nanowire-nanowire (NWNW) junctions were also fabricated.  NWNW thermocouples measure temperature accurately and reproducibly, and have a response time of 0.7ms.  Neither type of nanowire- based thermocouple show a decrease in sensitivity.   The characterization of these thermocouple arrays by SEM, EDS, and thermal measurements will be presented.

4
Author(s)::	K. Callahan, M. Roeselova, D.J. Tobias (email:  callahak@uci.edu)
Affiliation(s)::	Department of Chemistry, UC Irvine
Title::	Molecular Dynamics Simulations of the Influence of Magnesium Dication on Aqueous Salt Solutions
Abstract::	Field studies and laboratory measurements have demonstrated that molecular chlorine is produced via oxidation of sea salt aerosol by hydroxyl radical.  A surface mechanism for chloride production was proposed based on molecular dynamics simulations of concentrated sodium chloride solutions, which predicted that chloride anions adsorb to the solution-air interface.  Sea water contains a substantial amount of magnesium chloride in addition to sodium chloride.  The present study seeks to quantify the effects of magnesium dications on the interfacial propensity and reactivity of chloride anion.  To this end, molecular dynamics simulations of concentrated magnesium chloride and sodium chloride solutions, as well as a model of sea water containing 85 mol% sodium chloride and 15 mol% magnesium chloride, were performed.  Structural and thermodynamic properties were calculated from the simulations and compared to available experimental data. The simulations show that the presence of magnesium dications does not effect the interfacial distribution of chloride anions.  In addition, the simulations predict that magnesium dications displace sodium cations in the model sea water system, and the presence of magnesium dications in the subsurface layer induces changes of the solvent structure in the interfacial region that could influence the surface reactivity of chloride anion.

5
Author(s)::	J. X. Cao (Juexian Cao) and R. Q. Wu (email: uexianc@uci.edu)
Affiliation(s)::	Department of Physics and Astronomy, UC Irvine
Title::	High piezoresistance effect in silicon nanowires
Abstract::	The silicon nanowires possess an unusually large piezoresistance effects compared with Si bulk (Nature nanotechnology, 1(2006), 42). Using first principle technique, we found that the high piezoresistance coefficient was traceable from the effective mass change effect with compressive strain. It is found that compressive strain would induce the change of the heavy effective mass band with a light effective mass band. The difference between the effective mass of those band is rather large compared with the valance band in p-type Si bulk. Due to those bands are surface states, the surface modification would play a vital role on the piezoresistance effects.

6
Author(s)::	P. Chu, D.L. Mills (email: pingc@uci.edu)
Affiliation(s)::	Department of Physics and Astronomy, UC Irvine
Title::	Laser Induced Forces Between Metallic Nanospheres; The Role of Collective Plasmon Resonances
Abstract::	We explore the theory of laser induced attractive forces between conducting nanospheres. Emphasis is placed on the influence of collective mode resonances on this force. As two spheres approach each other, the dipole active plasmon resonances drop in frequency and can pass through the laser frequency. This produces a dramatic enhancement of the force. We present explicit calculation for Ag nanospheres in solution. We compare the amplitude of the laser induced attractive force with the van der Waals forece. Research supported by the U.S. Department of Energy through Grant No. DE-FG03-84ER-45083.

7
Author(s)::	B. Goldsmith, J. Mannik, J.G. Coroneus A.A. Kane G.A. Weiss P.G. Collins (email:  bgoldsmi@uci.edu)
Affiliation(s)::	Department of Physics and Astronomy, UC Irvine
Title::	Fabrication of Single-Biomolecule Electronic Devices
Abstract::	New inventions in nanotechnology are likely to enable the investigation of biochemical reactions with single molecule precision.  One promising approach is the integration of bioactive molecules into electronic devices.  We present a two step method to build single protein sensors from carbon nanotube circuits.  In the first, feedback-controlled step, a single attachment site is introduced to the nanotube sidewall using electrochemical oxidation.  In the second step, the site is covalently linked to a protein's amide termination.  The resulting circuits incorporate a single functional molecule and allow interrogation under various environments and biochemical conditions

8
Author(s)::	Y. He, Z. Siwy (email: zsiwy@uci.edu)
Affiliation(s)::	Department of Physics and Astronomy, UC Irvine
Title::	Preparation of Synthetic Nanopores Selective for Calcium Channels
Abstract::	Ion channels in biological membranes are nanodevices selectively transporting one type of ion and excluding other ions. We have studied mechanism of calcium channel selectivity and have tested predictions of a particular theoretical model.  The model suggests that if there is a high density of carboxylate groups on walls of a nanometric channel, which ensures a high binding affinity for calcium ions, these groups will preferentially bind doubly charged calcium ions rather than monovalent ions like sodium. Predictions of this model have been tested with polymer nanopores of high suface charge density of COOH groups.

9
Author(s)::	C. Jo, R. Wu (email:cjo@uci.edu)
Affiliation(s)::	Department of Physics and Astronomy, UC Irvine
Title::	Interface Configuration in Fe/GaAs(001) and Induced Spin Polarization
Abstract::	We have calculated x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) of the interface in Fe/GaAs(001) by using the density functional full-potential linearized augmented plane wave method. Intermixing interface with As and substitutional Ga plausibly reproduces the experimental XAS/XMCD data of As and Ga. The XAS/XMCD curves are highly sensitive to the change of interface configurations, and thus provide a clue to determine the atomic structure of the interface between Fe and GaAs. The significant spin polarizations on As and Ga atoms are induced, which is the key factor for the carrier-induced magnetic ordering.

10
Author(s)::	E. Kalman, Z. Siwy (email: zsiwy@uci.edu)
Affiliation(s)::	Department of Physics and Astronomy, UC Irvine
Title::	Tuning of Ion Current Rectification in Asymmetric Nanopores by Signal Mixing
Abstract::	Transport properties of asymmetric and rectifying single nanopores in polymer films were studied in the presence of two periodic, rectangular voltage signals. We show that tuning the ratio of frequencies, the phase difference and amplitude of the two voltage inputs gives a new possibility to enhance, hinder or cancel the rectifying properties of the nanoporous system.

11
Author(s)::	A. Kane, B. Goldsmith, P.G. Collins (email:  akane@uci.edu)
Affiliation(s)::	Department of Physics and Astronomy, UC Irvine
Title::	High Temperature Resistance and Reactivity of Carbon Nanotube Electronic Circuits
Abstract::	At sufficiently high temperatures, carbon nanotubes (CNTs) begin to react with their immediate environment. For example, adsorbates first desorb, then the carbon may react with connective electrodes, and ultimately Stone-Wales defects become mobile and can be annealed. We have designed and built an apparatus to study electronic transport in individual CNTs under these extreme conditions. Our apparatus provides continuous, four probe measurements of impedance and transimpedance from room temperature to 1500 K in an ultrahigh vacuum (UHV) system. By heating the devices to such temperatures, we are able to study the onset and progress of reactions, and the UHV environment allows for precise control of the local surface chemistry. Furthermore, the devices can be heated either resistively or radiatively at rates exceeding 100 K/min, allowing for pulsed thermal processing and an investigation of photoinduced chemistries.We will present results on the high temperature resistance of CNT devices in a UHV environment, and preliminary results indicating irreversible chemical changes which occur at high temperatures.

12
Author(s)::	V. Khalap, A. Kane, P. G. Collins (email: vkhalap@uci.edu)
Affiliation(s)::	Department of Physics and Astronomy, UC Irvine
Title::	Chemoresistance of carbon nanotube circuits incorporating electrochemically-decorated defects
Abstract::	We specifically investigate SWNT devices with single point functionalizations. Standard fabrication techniques are supplemented by an electrochemical point-oxidation process that creates insulating defects into otherwise pristine SWNTs.  Selective electrochemistry subsequently deposits metal onto the insulating site(s) and restores the device conductivity.  Furthermore, the resulting circuits inherit the chemicalsensitivity of the metal deposits.

13
Author(s)::	M. Krisch, R. D’Auria, M.A. Brown, D.J. Tobias, J.C. Hemminger (email: mkrisch@uci.edu)
Affiliation(s)::	Department of Chemistry, UC Irvine
Title::	The effect of an organic on the interfacial structure of an electrolyte solution
Abstract::	The addition of 1-butanol to an aqueous potassium iodide solution modifies the interfacial profile of ions at the liquid - vapor interface.  Our experiments probe atomic composition at the liquid surface with ambient pressure x-ray photoelectron spectroscopy at beamline 11.0.2 of the Advanced Light Source.  Photoelectron kinetic energies are varied to produce a depth profile of the liquid - vapor interface.  Surface enhancement of iodide anions, an effect observed in aqueous potassium iodide solution, disappears in the presence of 1-butanol, a surface active alcohol.  Molecular dynamics simulations of butanol in an aqueous electrolyte solution observe the same effect.  Radial distribution functions show that butanol appears to interact with both the anion and the cation; this is likely to be the basis for the observed changes in the ion distribution in the presence of the organic.  Insight into ion behavior at mixed liquid surfaces is crucial for understanding the chemistry of atmospheric aerosols, which frequently contain mixtures of water, electrolytes, and organics.
	Markus Ammann Laboratory of Radio- and Environmental Chemistry, Paul Scherrer Institute, CH-5232 Villigen, Switzerland David E. Starr, Hendrik Bluhm Lawrence Berkeley National Laboratory, Mail Stop 6R2100, One Cyclotron Road, Berkeley, CA 94720

14
Author(s)::	R. J. Lazarowich and P. Taborek (1);  N. V. Myung (2) (email:  rlazarowich@gmail.com)
Affiliation(s)::	(1) Department of Physics and Astronomy, UC Irvine (2) Department of Chemical and Environmental Engineering, U C Riverside
Title::	Fabrication of Humidity Sensors Using Porous Alumina
Abstract::	Nanoporous alumina structures were fabricated on quartz crystal microbalances (QCMs) by electrochemically anodizing aluminum electrodes which had a typical thickness of 10-15 microns. By varying the temperature and voltage of anodization, the diameter of the cylindrical pores could be controlled in the range of 12 to 40 nm. Properties of the porous films were determined from SEM images and by analyzing isotherms of N$2$, O$2$, C$3$H$8$, and H$2$O. The sensitivity increased up to 120 times that of a conventional QCM with flat electrodes. With a long-range order of cylindrical pores and enhanced sensitivity, these devices are prime candidates for use as sensors and templates. A subsequent experiment under constant flow of N$2$ near room temperature shows that QCMs with porous alumina electrodes are very sensitive to the condensation of water, therefore, making them excellent humidity sensors.

15
Author(s)::	J. Loussaert (email:jloussae@uci.edu)
Affiliation(s)::	Department of Chemistry, UC Irvine
Title::	The Characterization and Functionalization of Polymer Optical Waveguide Layers for Bio-Affinity Sensing
Abstract::	The technique of Optical Waveguide Layer Spectroscopy (OWLS) is demonstrated as new methodology for surface bioaffinity sensing.   OWLS uses a combination of a thin metal film and a thin polymer overlayer to create enhanced TE and TM-polarized electromagnetic fields within the film and at the biosensor surface. Chemical modification of the interface with bioaffinity probe molecules lead to the formation of biosensors for DNA, RNA, proteins and antibodies.

16
Author(s)::	Gang Qiu, M.M. Kobayashi, C.S. Tsai (email: cstsai@uci.edu)
Affiliation(s)::	Department of Electrical Engineering & Computer Science
Title::	Enhanced Microwave FMR Absorption in a YIG/GGG-GaAs Flip-Chip Layer  Structure Using Microstrip Step-Impedance Low-Pass Filter
Abstract::	Enhanced microwave ferromagnetic resonance (FMR) absorptions in yttrium  iron garnet / gadolinium gallium garnet-gallium arsenide (YIG/GGG-GaAs) flip-chip layer structures using a microstrip step-impedance low-pass filter (LPF) are reported. The field simulations of the step-impedance LPF show clearly that, in contrast to a 50   microstrip, the ac magnetic fields of the propagating microwaves are heavily concentrated in its inductive elements. Stronger local ac magnetic fields at each inductive element of the step-impedance LPF facilitate enhanced coupling into the magnetic over-layer and, thus, significantly increase the microwave power absorptions at the FMR frequencies. The measured transmission loss (S21) and return loss (S11) of –25.0 dB and –8.7 dB using the microstrip step-impedance LPF, at FMR frequency of 8.5 GHz, show a higher level of microwave FMR absorption in the YIG/GGG-GaAs layer structure as compared to a 50   microstrip with the measured S21 and S11 of –20.8 dB and –5.8 dB. The microwave transmission characteristics of the magnetic over-layer in a large base band of 2.0-20.0 GHz, using both the step-impedance LPF and the 50   microstrip, were also measured and compared. Sponsor: This work was supported in part by the UC Discovery Program

17
Author(s)::	A. A. Shinde C. Jo J.P. You J. Choi R. Wu R. Ragan (email: ashinde@uci.edu)
Affiliation(s)::	Department of Physics and Astronomy / ChEMS UC Irvine
Title::	Fabrication, Optimization and Modeling of Highly Ordered Assemblies of Monodisperse Metallic Nanostructure Arrays
Abstract::	Metal nanostructures have demonstrated extraordinary properties: the capacity for single molecule detection in plasmon resonance biosensors, chemical sensitivity and higher performance in catalytic processes than their bulk counterparts, and the transport of electromagnetic energy along particle chains in optical circuits.  One of the most significant challenges to technical developments that capitalize on unique properties of metal nanostructures is the fabrication of nanostructure arrays with monodisperse size, shape and high density using low cost and high throughput technique.  We will present a unique Si-compatible fabrication process for dense ordered arrays (~1011 cm 2) of metal nanostructures with monodisperse size and shape, over large area ( >1mm2), and having feature size and inter-particle spacing unattainable with state of the art electron beam lithography. Noble metal deposited via physical vapor deposition on a nanowire template combined with reactive ion etching produced noble metal core-shell nanowire and nanoparticle arrays with mean feature size of approximately 8 nm.  Hexagonal rare earth disilicide nanowires, such as DySi2 and ErSi2, are used as self-assembled nanowire templates on Si(001).  Dense arrays of parallel DySi2 and ErSi2 nanowires having lengths greater than 1 micron and widths less than 5 nm have been fabricated and characterized on vicinal Si(001) previously.  Scanning tunneling microscopy has shown than platinum (gold) forms clusters on the ErSi2 (DySi2) nanowire surfaces, and scanning electron microscopy backscattered images have shown that noble metal preferentially aggregates on the nanowire surfaces as opposed to the Si substrate.  Noble metal coverage is used to select nanoparticle versus nanowire arrays after RIE.  In the case of nanoparticles, a narrow size distribution of less than than ±1 nm and inter-particle spacing of approximately 10 nm is obtained by our process.  Few studies have been done on the theory behind the formation of the nanowire templates as well as the phenomena of preferential aggregation of noble metal on nanowire surfaces.  Thus, theoretical modeling is combined with scanning probe microscopy in order to gain a deeper understanding of thermodynamics and kinetics driving nanostructure formation.  We will also present ongoing work that uses VASP, an ab initio software package, to simulate RESi2 crystal structures as well as metal atoms on nanowire surfaces.  Our preliminary calculations for bulk YSi2 have been found to be in close agreement with experiment and other theoretical studies.  Our goal is to understand assembly mechanisms in order to optimize structure and make our process applicable to other material systems.

18
Author(s)::	I. Vlassiouk, Z. Siwy (email: zsiwy@uci.edu)
Affiliation(s)::	Department of Physics and Astronomy, UC Irvine
Title::	Nanofluidic diode
Abstract::	We present a nanofluidic diode that at voltage range (-5 V, +5V) rectifies ion current with degrees of rectification reaching several hundreds. The diode is based on a single asymmetric nanopore whose surface was patterned so that a sharp boundary between positively and negatively charged regions is created. This boundary defines a zone that is enriched with positive and negative ions or creates a depletion zone. The principle of operation of the nanofluidic diode is analogues to that of a bipolar semiconductor diode.

19
Author(s)::	S. Wu (1), N. Ogawa (2), W. Ho (1,3) (email: shiweiw@uci.edu)
Affiliation(s)::	1 Department of Physics and Astronomy, UC Irvine 2 Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo 153-8904, Japan, 3 Department of Chemistry, UC Irvine
Title::	Atomic-scale coupling of photons to single-molecule junctions
Abstract::	The study of optical phenomena at the atomic scale is expected to provide new understanding of molecules and their chemical dynamics. The combination of lasers with a low temperature scanning tunneling microscope (STM) has led to the observation of photo-induced resonant tunneling with sub-molecular spatial resolution for electron transfer to a single molecule adsorbed on a solid surface [Science 312, 1362, (2006)]. Furthermore, irradiation of femtosecond laser pulses into this single-molecule junction defined by STM results in non-linear coupling by two-photon excitation, rather than the single-photon coupling in the case of continuous wave (CW) lasers. These experiments lead to new opportunities by tapping into the unique properties of lasers and the STM.

20
Author(s)::	C. Xiang, M.A. Thompson,  A.G. Güell,  E.J. Menke, R. M. Penner (email: cxiang@uci.edu)
Affiliation(s)::	Department of Chemistry, U C Irvine
Title::	Lithographically Patterned Nanowire Electrodeposition
Abstract::	Nanowire fabrication methods can be classified either as “top down”, involving photo- or electron beam lithography, or “bottom-up”, involving the synthesis of nanowires from molecular precursors. Lithographically Patterned Nanowire Electrodeposition (LPNE) combines attributes of photolithography with the versatility of bottom-up electrochemical synthesis. Photolithography is employed to define the position of a sacrificial nickel nanoband electrode that is recessed into a horizontal trench defined by the substrate surface and photoresist. This trench acts as a “nanoform” to define the height of an incipient nanowire during its electrodeposition.  The width of the nanowire is determined by the electrodeposition duration.  Removal of the photoresist and nickel reveals a nanowire - composed of gold, platinum or palladium – with a rectangular cross section and a height and width that can be independently controlled, and as small as 10 nm. The polycrystalline nanowires synthesized by LPNE can be electrically continuous for 1 cm. Application of LPNE synthesized nanowires including thermocouples, crossed wires, and bimetallic wire arrays are briefly explored.

21
Author(s)::	L.C. Yang, P.Y. Tam, J. Diaz, T.M. McIntire, B.J. Murray, C.M. Overstreet, G.A. Weiss, R.M. Penner (email:  lcyang@uci.edu)
Affiliation(s)::	Department of Chemistry, UC Irvine
Title::	Electrodes for Biodetection
Abstract::	The development of label-free biosensors for key biomolecules is an objective that is shared by many research groups worldwide.  We present an approach involving the electrochemical detection of biomolecules binding to electrode surfaces on which an engineered bacteriophage, M13, has been covalently attached. This bacteriophage has - on its surface - polypeptide receptors that form the basis for molecular recognition.  These phage particles are prepared using the techniques of phage display.      We describe the preparation of the biosensor surface, the optimization of the electrochemical impedance and quartz crystal microbalance measurements, and the results of our experiments that involve the detection of antibodies that are recognized and bound by the immobilized phage particles, and “control” antibodies that are not recognized.  The response of this biosensor to the prostate cancer marker, PMSA, is also reported. In all cases, the observed impedance responses are “benchmarked” against the response of a quartz crystal microbalance, on which the biosensor is constructed.

22
Author(s)::	Donghyung Lee, Kieron Burke (email:  donghyul@uci.edu)
Affiliation(s)::	Department of Chemistry, UC Irvine
Title::	Negative Ions in DFT
Abstract::	The atomic electron affinities and densities are investigated using density functional methods (LDA, GGA) with both large basis sets and using OEP densities on a numerical basis, and the results are compared. The instability of negative ions in DFT is a well-known problem.[1,2] In the case of negative ions such as H¯ and F¯, the incorrect asymptotic single particle potential and density decay lead to unbound systems. In this work, we show the functional dependence of the extra electron density behavior in asymptotic region and how the values of electron affinity are significantly improved by using OEP densities. [1] Galbraith, J.M., et al, J. Chem. Phys. 105, 862, 1996 [2] Rosch, N., et al, J. Chem. Phys. 105, 862, 199

23
Author(s)::	Ilya Goldshleger, Galina Kerenskaya, Vahan Senekerymian, V. Ara Apakarian, and Kenneth C. Janda (email: igoldshl@uci.edu)
Affiliation(s)::	Department of Chemistry, UC Irvine
Title::	Bromine Hydrate: Microscopy, Spectroscopy, and Ultrfast Dynamics
Abstract::

24
Author(s)::	L. Pocivavsek, S. Frey, K. Krishan, H. Diamant. K.Y. Lee, M. Dennin (email: kkrishan@uci.edu)
Affiliation(s)::	Department of Physics & Astronomy, UC Irvine
Title::	Packing in Biphasic Monolayers: Origins and Effects on Collapse.
Abstract::	One of the inherent limitations of standard Langmuir monolayer troughs is the rectangular geometry used. Here, one or two barriers are used to reduce the area of the system with the other boundaries remaining stationary. The compression in this geometry is anisotropic, and prone to shear stresses and flows. Such influence of externally imposed symmetries  on microscopic dynamics in monolayers has not been investigated systematically. Our current experiments attempt to understand this in relation to DPPC:POPG monolayers by subjecting them to circularly symmetric compression. These monolayers are similar to those used as lung surfactants, where monolayer compression and dilation are essential. These surfactants also have a novel mechanism of collapse through reversible folding. The folding seen in these surfactants reflect the symmetries of the compression in rectangular geometries. In addition, spatial structure of domains have also been observed to have symmetries that may be associated with the symmetry of compression. The use of circularly symmetric compression contrasted with linear compression is expected to clarify aspects of spatial structure formation in monolayers that may be associated with the geometry of  compression.