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IBS and Expected Luminosity Performance For RHIC Beams At Top Energy With 56 MHz SRF Cavity (open access)

IBS and Expected Luminosity Performance For RHIC Beams At Top Energy With 56 MHz SRF Cavity

N/A
Date: October 1, 2008
Creator: A., Fedotov
Object Type: Report
System: The UNT Digital Library
RHIC Performance with 56 MHz RF and Gold Ion Beams Pre-cooled at Lower Energy (open access)

RHIC Performance with 56 MHz RF and Gold Ion Beams Pre-cooled at Lower Energy

N/A
Date: October 1, 2008
Creator: A., Fedotov
Object Type: Report
System: The UNT Digital Library
FFAG Accelerator Proton Driver for Neutrino Factory (open access)

FFAG Accelerator Proton Driver for Neutrino Factory

N/A
Date: October 1, 2005
Creator: A., Ruggiero
Object Type: Report
System: The UNT Digital Library
PROPOSAL FOR A SILICON VERTEX TRACKER (VTX) FOR THE PHENIX EXPERIMENT (open access)

PROPOSAL FOR A SILICON VERTEX TRACKER (VTX) FOR THE PHENIX EXPERIMENT

We propose the construction of a Silicon Vertex Tracker (VTX) for the PHENIX experiment at RHIC. The VTX will substantially enhance the physics capabilities of the PHENIX central arm spectrometers. Our prime motivation is to provide precision measurements of heavy-quark production (charm and beauty) in A+A, p(d)+A, and polarized p+p collisions. These are key measurements for the future RHIC program, both for the heavy ion program as it moves from the discovery phase towards detailed investigation of the properties of the dense nuclear medium created in heavy ion collisions, and for the exploration of the nucleon spin-structure functions. In addition, the VTX will also considerably improve other measurements with PHENIX. The main physics topics addressed by the VTX are: (1) Hot and dense strongly interacting matter--(a) Potential enhancement of charm production, (b) Open beauty production, (c) Flavor dependence of jet quenching and QCD energy loss, (d) Accurate charm reference for quarkonium, (e) Thermal dilepton radiation, (f) High p{sub T} phenomena with light flavors above 10-15 GeV/c in p{sub T}, and (g) Upsilon spectroscopy in the e{sup +}e{sup -} decay channel. (2) Gluon spin structure of the nucleon--(a) {Delta}G/G with charm, (b) {Delta}G/G with beauty, and (c) x dependence of {Delta}G/G …
Date: October 1, 2004
Creator: AKIBA,Y.
Object Type: Report
System: The UNT Digital Library
HYBRIDIZATION AND PRESSURE EFFECTS IN UTX COMPOUNDS (open access)

HYBRIDIZATION AND PRESSURE EFFECTS IN UTX COMPOUNDS

None
Date: October 1, 2001
Creator: ALSAMDI, A.; SECHOVSKY, V. & AL, ET
Object Type: Article
System: The UNT Digital Library
Construction and Testing of a Low-power Cryostat for MARS (open access)

Construction and Testing of a Low-power Cryostat for MARS

A low-power cryostat was designed and built for the Multi-sensor Airborne Radiation Survey (MARS) project for the purpose of housing a close-packed high-purity germanium (HPGe) detector array of 14 HPGe detectors. The power consumption of the cold mass in the cryostat was measured to be 4.07(11) watts, sufficient for 5.5 days of continuous operation using only 8 liters of liquid nitrogen. Temperatures throughout the cryostat were measured by platinum resistance temperature detectors. These measurements were used to determine the emissivity of the copper used in the floating radiation shield and outer cryostat wall, which was constructed using chemically cleaned and passivated copper metal. Using a PNNL-developed passivation process, an emissivity of 2.5(3)% was achieved for copper.
Date: October 1, 2007
Creator: Aalseth, Craig E.; Caggiano, Joseph A.; Day, Anthony R.; Fast, James E. & Fuller, Erin S.
Object Type: Report
System: The UNT Digital Library
Search for Standard Model Higgs Bosons Produced in Association with W Bosons (open access)

Search for Standard Model Higgs Bosons Produced in Association with W Bosons

The authors report on the results of a search for standard model Higgs bosons produced in association with W bosons from p{bar p} collisions at {radical}s = 1.96 TeV. The search uses a data sample corresponding to approximately 1 fb{sup -1} of integrated luminosity. Events consistent with the W {yields} {ell}{nu} and H {yields} b{bar b} signature are selected by triggering on a high-p{sub T} electron or muon candidate and tagging one or two of the jet candidates as having originated from b quarks. A neural network filter rejects a fraction of tagged charm and light flavor jets, increasing the b-jet purity in the sample and thereby reducing the background to Higgs boson production. They observe no excess {ell}{nu}b{bar b} production beyond the background expectation, and they set 95% confidence level upper limits on the production cross section times branching fraction {sigma}(p{bar p} {yields} WH) {center_dot} Br(H {yields} b{bar b}) ranging from 3.9 to 1.3 pb, for specific Higgs boson mass hypotheses in the range 110 to 150 GeV/c{sup 2}, respectively.
Date: October 1, 2007
Creator: Aaltonen, T.
Object Type: Article
System: The UNT Digital Library
Measurements of the top-quark mass using charged particle tracking (open access)

Measurements of the top-quark mass using charged particle tracking

We present three measurements of the top-quark mass in the lepton plus jets channel with approximately 1.9 fb{sup -1} of integrated luminosity collected with the CDF II detector using quantities with minimal dependence on the jet energy scale. One measurement exploits the transverse decay length of b-tagged jets to determine a top-quark mass of 166.9{sub -8.5}{sup +9.5} (stat) {+-} 2.9 (syst) GeV/c{sup 2}, and another the transverse momentum of electrons and muons from W-boson decays to determine a top-quark mass of 173.5{sub -8.9}{sup +8.8} (stat) {+-} 3.8 (syst) GeV/c{sup 2}. These quantities are combined in a third, simultaneous mass measurement to determine a top-quark mass of 170.7 {+-} 6.3 (stat) {+-} 2.6 (syst) GeV/c{sup 2}.
Date: October 1, 2009
Creator: Aaltonen, T.; Adelman, J.; Akimoto, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D. et al.
Object Type: Article
System: The UNT Digital Library
Measurement of the Inclusive Isolated Prompt Photon Cross Section in ppbar Collisions at sqrt{s} = 1.96 TeV using the CDF Detector (open access)

Measurement of the Inclusive Isolated Prompt Photon Cross Section in ppbar Collisions at sqrt{s} = 1.96 TeV using the CDF Detector

A measurement of the cross section for the inclusive production of isolated photons by the CDF experiment at the Fermilab Tevatron collider is presented. The measurement covers the pseudorapidity region |{eta}{sup {gamma}}| < 1.0 and the transverse energy range E{sub T}{sup {gamma}} > 30 GeV and is based on 2.5 fb{sup -1} of integrated luminosity. The sample is almost a factor of seven larger than those used for recent published results and extends the E{sub T}{sup {gamma}} coverage by 100 GeV. The result agrees with next-to-leading order perturbative QCD calculations within uncertainties over the range 50 < E{sub T}{sup {gamma}} < 400 GeV, though the energy spectrum in the data shows a steeper slope at lower E{sub T}{sup {gamma}}.
Date: October 1, 2009
Creator: Aaltonen, T.; Adelman, J.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A. et al.
Object Type: Article
System: The UNT Digital Library
Search for Anomalous Production of Events with Two Photons and Additional Energetic Objects at CDF (open access)

Search for Anomalous Production of Events with Two Photons and Additional Energetic Objects at CDF

The authors present results of a search for anomalous production of two photons together with an electron, muon, {tau} lepton, missing transverse energy, or jets using p{bar p} collision data from 1.1-2.0 fb{sup -1} of integrated luminosity collected by the Collider Detector at Fermilab (CDF). The event yields and kinematic distributions are examined for signs for new physics without favoring a specific model of new physics. The results are consistent with the standard model expectations. The search employs several new analysis techniques that significantly reduce instrumental backgrounds in channels with an electron and missing transverse energy.
Date: October 1, 2009
Creator: Aaltonen, T.; Adelman, J.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A. et al.
Object Type: Article
System: The UNT Digital Library
Search for Supersymmetry with Gauge-Mediated Breaking in Diphoton Events with Missing Transverse Energy at CDF II (open access)

Search for Supersymmetry with Gauge-Mediated Breaking in Diphoton Events with Missing Transverse Energy at CDF II

The authors present the results of a search for supersymmetry with gauge-mediated breaking and {tilde {chi}}{sub 1}{sup 0} {yields} {gamma}{tilde G} in the {gamma}{gamma} + missing transverse energy final state. In 2.6 {+-} 0.2 fb{sup -1} of p{bar p} collisions at {radical}s = 1.96 TeV recorded by the CDF II detector they observe no candidate events, consistent with a standard model background expectation of 1.4 {+-} 0.4 events. They set limits on the cross section at the 95% C.L. and place the world's best limit of 149 GeV/c{sup 2} on the {tilde {chi}}{sub 1}{sup 0} mass at {tau}{sub {tilde {chi}}{sub 1}{sup 0}} << 1 ns. They also exclude regions in the {tilde {chi}}{sub 1}{sup 0} mass-lifetime plane of {tau}{sub {tilde {chi}}{sub 1}{sup 0}} {approx}< 2 ns.
Date: October 1, 2009
Creator: Aaltonen, T.; Adelman, J.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A. et al.
Object Type: Article
System: The UNT Digital Library
Search for High-Mass \boldmath$e^+e^-$ Resonances in \boldmath$p\bar{p}$ Collisions at \boldmath$\sqrt{s}=$1.96 TeV (open access)

Search for High-Mass \boldmath$e^+e^-$ Resonances in \boldmath$p\bar{p}$ Collisions at \boldmath$\sqrt{s}=$1.96 TeV

A search for high-mass resonances in the e{sup +}e{sup -} final state is presented based on {radical}s =1.96 TeV p{bar p} collision data from the CDF II detector at the Fermilab Tevatron from an integrated luminosity of 2.5 fb{sup -1}. The largest excess over the standard model prediction is at an e{sup +}e{sup -} invariant mass of 240 GeV/c{sup 2}. The probability of observing such an excess arising from fluctuations in the standard model anywhere in the mass range of 150-1,000 GeV/c{sup 2} is 0.6% (equivalent to 2.5 {sigma}). We set Bayesian upper limits on {sigma}(p{bar p} {yields} X) {center_dot} {Beta}(X {yields} e{sup +}e{sup -}) at the 95% credibility level, where X is a spin 1 or spin 2 particle, and we exclude the standard model coupling Z{prime} and the Randall-Sundrum graviton for {kappa}/{bar M}{sub Pl} = 0.1 with masses below 963 and 848 GeV/c{sup 2}, respectively.
Date: October 1, 2008
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Adelman, J.; /Chicago U., EFI; Akimoto, T.; U., /Tsukuba et al.
Object Type: Article
System: The UNT Digital Library
Evidence of WW+WZ production with lepton + jets final states in p anti-p collisions at s**(1/2) = 1.96-TeV (open access)

Evidence of WW+WZ production with lepton + jets final states in p anti-p collisions at s**(1/2) = 1.96-TeV

We present the first evidence of WW+WZ production with lepton+jets final states at a hadron collider. The data correspond to 1.07 inverse femtobarns of integrated luminosity collected with the D0 detector at the Fermilab Tevatron Collider in proton-antiproton collisions at sqrt(s)=1.96 TeV. The observed cross section for WW+WZ production is 20.2 +/- 4.5 pb, consistent with the SM prediction of 16.1 +/- 0.9 pb. The probability for background fluctuations to produce an excess equal to or larger than that observed is estimated to be 5.4e-6, corresponding to a significance of 4.4 standard deviations.
Date: October 1, 2008
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
Object Type: Article
System: The UNT Digital Library
Atmospheric Mercury Concentrations Near Salmon Falls Creek Reservoir - Phase 1 (open access)

Atmospheric Mercury Concentrations Near Salmon Falls Creek Reservoir - Phase 1

Elemental and reactive gaseous mercury (EGM/RGM) were measured in ambient air concentrations over a two-week period in July/August 2005 near Salmon Falls Creek Reservoir, a popular fishery located 50 km southwest of Twin Falls, Idaho. A fish consumption advisory for mercury was posted at the reservoir in 2002 by the Idaho Department of Health and Welfare. The air measurements were part of a multi-media (water, sediment, precipitation, air) study initiated by the Idaho Department of Environmental Quality and the U.S. Environmental Protection Agency (EPA) Region 10 to identify potential sources of mercury contamination to the reservoir. The sampling site is located about 150 km northeast of large gold mining operations in Nevada, which are known to emit large amounts of mercury to the atmosphere (est. 2,200 kg/y from EPA 2003 Toxic Release Inventory). The work was co-funded by the Idaho National Laboratory’s Community Assistance Program and has a secondary objective to better understand mercury inputs to the environment near the INL, which lies approximately 230 km to the northeast. Sampling results showed that both EGM and RGM concentrations were significantly elevated (~ 30 – 70%, P<0.05) compared to known regional background concentrations. Elevated short-term RGM concentrations (the primary form that …
Date: October 1, 2005
Creator: Abbott, M. L.
Object Type: Report
System: The UNT Digital Library
Environmental Sampling FY03 Annual Report - Understanding the Movement of Mercury on the INEEL (open access)

Environmental Sampling FY03 Annual Report - Understanding the Movement of Mercury on the INEEL

Environmental mercury measurements were started in Fy-01 at the Idaho National Engineering Laboratory (INEEL) to monitor downwind impacts from on-going waste treatment operations at the Idaho Nuclear Technology and Engineering Center (INTEC) and to improve our scientific understanding of mercury fate and transport in this region. This document provides a summary of the sampling done in FY04. Continuous total gaseous mercury (TGM) measurements were made using a Tekran Model 2537A mercury vapor analyzer during October 2002 and from February through July 2003. The equipment was deployed in a self-contained field trailer at the Experimental Field Station (EFS) four kilometers downwind (northeast) of INTEC. Mercury surface-to-air flux measurements were made in October 2002 and from February through May 2003 to better understand the fate of the estimated 1500 kg of mercury emitted from 36 years of calciner operations at INTEC and to improve our scientific understanding of mercury environmental cycling in this region. Flux was measured using an INEEL-designed dynamic flux chamber system with a Tekran automated dual sampling (TADS) unit. Diel flux was positively correlated with solar radiation (r = 0.65), air temperature (r = 0.64), and wind speed (r = 0.38), and a general linear model for flux prediction …
Date: October 1, 2003
Creator: Abbott, Michael L.
Object Type: Report
System: The UNT Digital Library
A Fusion Chamber for the 2002 Robust Point Design (open access)

A Fusion Chamber for the 2002 Robust Point Design

A top-level overview of the mechanical design for the 2002 Robust Point Design (RPD-2002) fusion chamber is introduced. It is based on the HYLIFE-II design and includes modifications to the liquid pocket configuration and first structural wall (FSW), facilitates periodic maintenance or replacement of internal components, and is compliant with all other RPD-2002 parameters. This work has been carried out by constructing a parametric computer model capable of being updated as future changes become necessary.
Date: October 1, 2003
Creator: Abbott, R P
Object Type: Article
System: The UNT Digital Library
Effects of Light Scalar Mesons in eta -&gt; 3pi decay (open access)

Effects of Light Scalar Mesons in eta -&gt; 3pi decay

We study the role of a possible nonet of light scalar mesons in the still interesting [eta] -&gt; 3[p]i decay process, with the primary motivation of learning more about the scalars themselves. The framework is a conventional non-linear chiral Lagrangian of pseudoscalars and vectors extended to include the scalars. The parameters involving the scalars were previously obtained to fit the s-wave [pi][pi] and [pi] K scatterings in the region up to about 1 GeV as well as the strong decay [eta]' --&gt; [eta][pi][pi]. At first, one might expect a large enhancement from diagrams including a light [sigma] (560). However there is an amusing cancellation mechanism which prevents this from occurring. In the simplest model there is an enhancement of about 13 per cent in the [eta] -&gt; 3[pi] decay rate due to the scalars. In a more complicated model which includes derivative type symmetry breakers, the cancellation is modified and the scalars contribute about 30 percent of the total decay rate (although the total is not significantly changed). The vectors do not contribute much. Our model produces a reasonable estimate for the related a{sub 0}(980) - f{sub 0}(980) mixing strength, which has been a topic of current debate. Promising directions …
Date: October 1, 2002
Creator: Abdel-Rehim, Abdou; Black, Deirdre; Fariborz, Amir H. & Schechter, Joseph
Object Type: Article
System: The UNT Digital Library
Noncontact surface thermometry for microsystems: LDRD final report. (open access)

Noncontact surface thermometry for microsystems: LDRD final report.

We describe a Laboratory Directed Research and Development (LDRD) effort to develop and apply laser-based thermometry diagnostics for obtaining spatially resolved temperature maps on working microelectromechanical systems (MEMS). The goal of the effort was to cultivate diagnostic approaches that could adequately resolve the extremely fine MEMS device features, required no modifications to MEMS device design, and which did not perturb the delicate operation of these extremely small devices. Two optical diagnostics were used in this study: microscale Raman spectroscopy and microscale thermoreflectance. Both methods use a low-energy, nonperturbing probe laser beam, whose arbitrary wavelength can be selected for a diffraction-limited focus that meets the need for micron-scale spatial resolution. Raman is exploited most frequently, as this technique provides a simple and unambiguous measure of the absolute device temperature for most any MEMS semiconductor or insulator material under steady state operation. Temperatures are obtained from the spectral position and width of readily isolated peaks in the measured Raman spectra with a maximum uncertainty near {+-}10 K and a spatial resolution of about 1 micron. Application of the Raman technique is demonstrated for V-shaped and flexure-style polycrystalline silicon electrothermal actuators, and for a GaN high-electron-mobility transistor. The potential of the Raman technique …
Date: October 1, 2006
Creator: Abel, Mark (Georgia Institute of Technology, Atlanta, GA); Beecham, Thomas (Georgia Institute of Technology, Atlanta, GA); Graham, Samuel (Georgia Institute of Technology, Atlanta, GA); Kearney, Sean Patrick; Serrano, Justin Raymond & Phinney, Leslie Mary
Object Type: Report
System: The UNT Digital Library
Adaptive Control Optimization of Cutting Parameters for High Quality Machining Operations based on Neural Networks and Search Algorithms (open access)

Adaptive Control Optimization of Cutting Parameters for High Quality Machining Operations based on Neural Networks and Search Algorithms

This book chapter presents an Adaptive Control with Optimization (ACO) system for optimising a multi-objective function based on material removal rate, quality loss function related to surface roughness, and cutting-tool life subjected to surface roughness specifications constraint.
Date: October 1, 2008
Creator: Abellan, J. V.; Romero, F.; Siller Carrillo, Héctor Rafael; Estruch, A. & Vila, C.
Object Type: Book Chapter
System: The UNT Digital Library
Prototype Weigh-In-Motion Performance (open access)

Prototype Weigh-In-Motion Performance

Oak Ridge National Laboratory (ORNL) has developed and patented methods to weigh slowly moving vehicles. We have used this technology to produce a portable weigh-in-motion system that is robust and accurate. This report documents the performance of the second-generation portable weigh-in-motion prototype (WIM Gen II). The results of three modes of weight determination are compared in this report: WIM Gen II dynamic mode, WIM Gen II stop-and-go mode, and static (parked) mode on in-ground, static scales. The WIM dynamic mode measures axle weights as the vehicle passes over the system at speeds of 3 to 7 miles per hour (1.3 to 3.1 meters/second). The WIM stop-and-go mode measures the weight of each axle of the vehicle as the axles are successively positioned on a side-by-side pair of WIM measurement pads. In both measurement modes the center of balance (CB) and the total weight are obtained by a straight-forward calculation from axle weights and axle spacings. The performance metric is measurement error (in percent), which is defined as 100 x (sample standard deviation)/(average); see Appendix A for details. We have insufficient data to show that this metric is predictive. This report details the results of weight measurements performed in May 2005 …
Date: October 1, 2006
Creator: Abercrombie, Robert K; Beshears, David L; Hively, Lee M; Scudiere, Matthew B & Sheldon, Frederick T
Object Type: Report
System: The UNT Digital Library
NEW PARADIGM IN SEPARATIONS: MOLECULAR RECOGNITION MEMBRANES (open access)

NEW PARADIGM IN SEPARATIONS: MOLECULAR RECOGNITION MEMBRANES

None
Date: October 1, 2000
Creator: Abney, K.D. & Barr, M.E.
Object Type: Article
System: The UNT Digital Library
Measurement of the Ratios of Branching Fractions B(Bs -> Ds pi pi pi) / B(Bd -> Dd pi pi pi) and B(Bs -> Ds pi) / B(Bd -> Dd pi) (open access)

Measurement of the Ratios of Branching Fractions B(Bs -> Ds pi pi pi) / B(Bd -> Dd pi pi pi) and B(Bs -> Ds pi) / B(Bd -> Dd pi)

Using 355 pb{sup -1} of data collected by the CDF II detector in p{bar p} collisions at {radical}s = 1.96 TeV at the Fermilab Tevatron, they study the fully reconstructed hadronic decays B{sub (s)}{sup 0} {yields} D{sub (s)}{sup -}{pi}{sup +} and B{sub (s)}{sup 0} {yields} D{sub (s)}{sup -} {pi}{sup +}{pi}{sup +}{pi}{sup -}. They present the first measurement of the ratio of branching fractions {Beta}(B{sub s}{sup 0} {yields} D{sub s}{sup -}{pi}{sup +}{pi}{sup +}{pi}{sup -})/{Beta}(B{sup 0} {yields} D{sup -} {pi}{sup +}{pi}{sup +}{pi}{sup -}) = 1.05 {+-} 0.10(stat.) {+-} 0.22(syst.). They also update their measurement of {Beta}(B{sub s}{sup 0} {yields} D{sub s}{sup -} {pi}{sup +})/{Beta}(B{sup 0} {yields} D{sup -} {pi}{sup +}) to 1.13 {+-} 0.08(stat.) {+-} 0.23(syst.) improving the statistical uncertainty by more than a factor of two. They find {Beta}(B{sub s}{sup 0} {yields} D{sub s}{sup -} {pi}{sup +}) = [3.8 {+-} 0.3(stat.) {+-} 1.3(syst.)] x 10{sup -3} and {Beta}(B{sub s}{sup 0} {yields} D{sub s}{sup -} {pi}{sup +}{pi}{sup +}{pi}{sup -}) = [8.4 {+-} 0.8(stat.) {+-} 3.2(syst.)] x 10{sup -3}.
Date: October 1, 2006
Creator: Abulencia, A.; /Illinois U., Urbana; Adelman, J.; U., /Chicago; Affolder, T.; /UC, Santa Barbara et al.
Object Type: Article
System: The UNT Digital Library
A Detailed Chemical Kinetic Analysis of Low Temperature Non-Sooting Diesel Combustion (open access)

A Detailed Chemical Kinetic Analysis of Low Temperature Non-Sooting Diesel Combustion

We have developed a model of the diesel fuel injection process for application to analysis of low temperature non-sooting combustion. The model uses a simplified mixing correlation and detailed chemical kinetics, and analyzes a parcel of fuel as it moves along the fuel jet, from injection into evaporation and ignition. The model predicts chemical composition and soot precursors, and is applied at conditions that result in low temperature non-sooting combustion. Production of soot precursors is the first step toward production of soot, and modeling precursor production is expected to give insight into the overall evolution of soot inside the engine. The results of the analysis show that the model has been successful in describing many of the observed characteristics of low temperature combustion. The model predicts results that are qualitatively similar to those obtained for soot formation experiments at conditions in which the EGR rate is increased from zero to very high values as the fueling rate is kept constant. The model also describes the two paths to achieve non-sooting combustion. The first is smokeless rich combustion and the second is modulated kinetics (MK). The importance of the temperature after ignition and the equivalence ratio at the time of ignition …
Date: October 1, 2004
Creator: Aceves, S M & Flowers, D L
Object Type: Article
System: The UNT Digital Library
Macro-ions collapse leading to hybrid bio-nanomaterials. (open access)

Macro-ions collapse leading to hybrid bio-nanomaterials.

I used supramolecular self-assembling cyanine and the polyamine spermine binding to Escherichia coli genomic DNA as a model for DNA collapse during high throughput screening. Polyamine binding to DNA converts the normally right handed B-DNA into left handed Z-DNA conformation. Polyamine binding to DNA was inhibited by the supramolecular self-assembling cyanine. Self-assembly of cyanine upon DNA scaffold was likewise competitively inhibited by spermine as signaled by fluorescence quench from DNA-cyanine ensemble. Sequence of DNA exposure to cyanine or spermine was critical in determining the magnitude of fluorescence quench. Methanol potentiated spermine inhibition by &gt;10-fold. The IC{sub 50} for spermine inhibition was 0.35 {+-} 0.03 {micro}M and the association constant Ka was 2.86 x 10{sup -6}M. Reversibility of the DNA-polyamine interactions was evident from quench mitigation at higher concentrations of cyanine. System flexibility was demonstrated by similar spermine interactions with {lambda}DNA. The choices and rationale regarding the polyamine, the cyanine dye as well as the remarkable effects of methanol are discussed in detail. Cyanine might be a safer alternative to the mutagenic toxin ethidium bromide for investigating DNA-drug interactions. The combined actions of polyamines and alcohols mediate DNA collapse producing hybrid bio-nanomaterials with novel signaling properties that might be useful in …
Date: October 1, 2009
Creator: Achyuthan, Komandoor E.
Object Type: Report
System: The UNT Digital Library