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2009

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Combination Of Tt Cross Section Measurements And Constraints On The Mass Of The Top Quark And Its Decays Into Charged Higgs Bosons, V. M. Abazov, Kenneth A. Bloom, Gregory Snow, D0 Collaboration Jan 2009

Combination Of Tt Cross Section Measurements And Constraints On The Mass Of The Top Quark And Its Decays Into Charged Higgs Bosons, V. M. Abazov, Kenneth A. Bloom, Gregory Snow, D0 Collaboration

Kenneth Bloom Publications

We combine measurements of the top quark pair production cross section in pp collisions in the ℓ + jets, ℓℓ, and τℓ final states (where ℓ is an electron or muon) at a center of mass energy of √s = 1.96 TeV in 1 fb-1 of data collected with the D0 detector. For a top quark mass of 170 GeV/c2, we obtain σtt = 8.18-0.87+0.98 pb in agreement with the theoretical prediction. Based on predictions from higher order quantum chromodynamics, we extract a mass for the top quark from the combined tt …

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Search For Charged Higgs Bosons In Decays Of Top Quarks, V. M. Abazov, Kenneth A. Bloom, Gregory Snow, D0 Collaboration Jan 2009

Search For Charged Higgs Bosons In Decays Of Top Quarks, V. M. Abazov, Kenneth A. Bloom, Gregory Snow, D0 Collaboration

Kenneth Bloom Publications

We present a search for charged Higgs bosons in decays of top quarks, in the mass range 80 < mH± < 155 GeV, assuming the subsequent decay H+ → τ+vτ (and its charge conjugate). Using 0.9 fb-1 of lepton + jets data collected with the D0 detector at the Fermilab Tevatron pp collider, operating at a center of mass energy √s = 1.96 TeV, we find no evidence for a H± signal. Hence we exclude branching ratios B(t → H+b) > 0.24 for mH± = 80 GeV and B(t → H …

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Observation Of Single Top-Quark Production, V. M. Abazov, Kenneth A. Bloom, Gregory Snow, D0 Collaboration Jan 2009

Observation Of Single Top-Quark Production, V. M. Abazov, Kenneth A. Bloom, Gregory Snow, D0 Collaboration

Kenneth Bloom Publications

We report observation of the electroweak production of single top quarks in pp collisions at √s = 1.96 TeV based on 2.3 fb-1 of data collected by the D0 detector at the Fermilab Tevatron Collider. Using events containing an isolated electron or muon and missing transverse energy, together with jets originating from the fragmentation of b quarks, we measure a cross section of σ(pp → tb + X, tqb + X) = 3.94 ± 0.88 pb. The probability to measure a cross section at this value or higher in the absence of signal is 2.5 x 10 …

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Measurement Of The ZΓ → Ννγ Production Cross Section And Limits On Anomalous ZzΓ And ZΓγ Couplings In Pp Collisions At √S= 1.96 Tev, V. M. Abazov, Kenneth A. Bloom, Gregory Snow, D0 Collaboration Jan 2009

Measurement Of The ZΓ → Ννγ Production Cross Section And Limits On Anomalous ZzΓ And ZΓγ Couplings In Pp Collisions At √S= 1.96 Tev, V. M. Abazov, Kenneth A. Bloom, Gregory Snow, D0 Collaboration

Kenneth Bloom Publications

We present the first observation of the Zγ → ννγ process at the Fermilab Tevatron at 5.1 standard deviations significance, based on 3.6 fb-1 of integrated luminosity collected with the D0 detector at the Fermilab Tevatron pp Collider at √s = 1.96 TeV. The measured Zγ production cross section multiplied by the branching fraction of Z → νν is 32 ± 9(stat + syst) ± 2(lumi) fb for the photon ET > 90 GeV. It is in agreement with the standard model prediction of 39 ± 4 fb. We set limits on anomalous trilinear Zγγ …

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Measurement Of The W Boson Mass, V. M. Abazov, Kenneth A. Bloom, Gregory Snow, D0 Collaboration Jan 2009

Measurement Of The W Boson Mass, V. M. Abazov, Kenneth A. Bloom, Gregory Snow, D0 Collaboration

Kenneth Bloom Publications

We present a measurement of the W boson mass in W → ev decays using 1 fb-1 of data collected with the D0 detector during Run II of the Fermilab Tevatron collider. With a sample of 499830 W → ev candidate events, we measure MW = 80.401 ± 0.043 GeV. This is the most precise measurement from a single experiment.

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Measurement Of Dijet Angular Distributions At √S = 1.96 Tev And Searches For Quark Compositeness And Extra Spatial Dimensions, V. M. Abazov, Kenneth A. Bloom, Gregory R. Snow, D0 Collaboration Jan 2009

Measurement Of Dijet Angular Distributions At √S = 1.96 Tev And Searches For Quark Compositeness And Extra Spatial Dimensions, V. M. Abazov, Kenneth A. Bloom, Gregory R. Snow, D0 Collaboration

Kenneth Bloom Publications

We present the first measurement of dijet angular distributions in pp collisions at √s = 1.96 TeV at the Fermilab Tevatron Collider. The measurement is based on a dataset corresponding to an integrated luminosity of 0:7 fb-1 collected with the D0 detector. Dijet angular distributions have been measured over a range of dijet masses, from 0.25 TeV to above 1.1 TeV. The data are in good agreement with the predictions of perturbative QCD and are used to constrain new physics models including quark compositeness, large extra dimensions, and TeV-1 scale extra dimensions. For all models considered, we …

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Direct Measurement Of The Mass Difference Between Top And Antitop Quarks, V. M. Abazov, Kenneth A. Bloom, Gregory Snow, D0 Collaboration Jan 2009

Direct Measurement Of The Mass Difference Between Top And Antitop Quarks, V. M. Abazov, Kenneth A. Bloom, Gregory Snow, D0 Collaboration

Kenneth Bloom Publications

We present a measurement of the mass difference between t and t quarks in lepton + jets final states of tt events in 1 fb-1 of data collected with the D0 detector from Fermilab Tevatron Collider pp collisions at √s = 1.96 TeV. The measured mass difference of 3.8 ± 3.7 GeV is consistent with the equality of t and t masses. This is the first direct measurement of a mass difference between a quark and its antiquark partner.

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Search For The Standard Model Higgs Boson In Tau Final States, V. M. Abazov, Kenneth A. Bloom, Gregory Snow, D0 Collaboration Jan 2009

Search For The Standard Model Higgs Boson In Tau Final States, V. M. Abazov, Kenneth A. Bloom, Gregory Snow, D0 Collaboration

Kenneth Bloom Publications

We present a search for the standard model Higgs boson using hadronically decaying tau leptons, in 1 fb-1 of data collected with the D0 detector at the Fermilab Tevatron pp collider. We select two final states: τ± plus missing transverse energy and b jets, and τ+τ- plus jets. These final states are sensitive to a combination of associated W/Z boson plus Higgs boson, vector boson fusion, and gluon-gluon fusion production processes. The observed ratio of the combined limit on the Higgs production cross section at the 95% C.L. to the standard model expectation is 29 …

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Search For Resonant Pair Production Of Neutral Long-Lived Particles Decaying To Bb In Pp Collisions At √S = 1.96 Tev, V. M. Abazov, Kenneth A. Bloom, Gregory R. Snow, D0 Collaboration Jan 2009

Search For Resonant Pair Production Of Neutral Long-Lived Particles Decaying To Bb In Pp Collisions At √S = 1.96 Tev, V. M. Abazov, Kenneth A. Bloom, Gregory R. Snow, D0 Collaboration

Kenneth Bloom Publications

We report on a first search for resonant pair production of neutral long-lived particles (NLLP) which each decay to a bb pair, using 3.6 fb-1 of data recorded with the D0 detector at the Fermilab Tevatron collider. We search for pairs of displaced vertices in the tracking detector at radii in the range 1.6–20 cm from the beam axis. No significant excess is observed above background, and upper limits are set on the production rate in a hidden-valley benchmark model for a range of Higgs boson masses and NLLP masses and lifetimes.

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Search For Next-To-Minimal Supersymmetric Higgs Bosons In The H → Aa → Μμμμ, Μμττ Channels Using Pp Collisions At √S = 1.96 Tev, V.M. Abazov, Kenneth A. Bloom, Gregory R. Snow, D0 Collaboration Jan 2009

Search For Next-To-Minimal Supersymmetric Higgs Bosons In The H → Aa → Μμμμ, Μμττ Channels Using Pp Collisions At √S = 1.96 Tev, V.M. Abazov, Kenneth A. Bloom, Gregory R. Snow, D0 Collaboration

Kenneth Bloom Publications

We report on a first search for production of the lightest neutral CP-even Higgs boson (h) in the next-to-minimal supersymmetric standard model, where h decays to a pair of neutral pseudoscalar Higgs bosons (a), using 4.2 fb-1 of data recorded with the D0 detector at Fermilab. The a bosons are required to either both decay to μ+μ- or one to μ+μ and the other to τ+τ. No significant signal is observed, and we set limits on its production as functions of Ma and Mh.

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Search For Long-Lived Charged Massive Particles With The D0 Detector, V. M. Abazov, Kenneth A. Bloom, Gregory Snow, D0 Collaboration Jan 2009

Search For Long-Lived Charged Massive Particles With The D0 Detector, V. M. Abazov, Kenneth A. Bloom, Gregory Snow, D0 Collaboration

Kenneth Bloom Publications

We search for long-lived charged massive particles using 1.1 fb-1 of data collected by the D0 detector at the Fermilab Tevatron pp Collider. Time-of-flight information is used to search for pair produced long-lived tau sleptons, gauginolike charginos, and Higgsino-like charginos. We find no evidence of a signal and set 95% C.L. cross section upper limits for staus, which vary from 0.31 to 0.04 pb for stau masses between 60 and 300 GeV. We also set lower mass limits of 206 GeV (171 GeV) for pair produced charged gauginos (Higgsinos).

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Self-Assembly Of Magnetic Ni Nanoparticles Into 1d Arrays With Antiferromagnetic Order, Valery Bliznyuk, Srikanth Singamaneni, Sarbeswar Sahoo, Srinivas Polisetty, Xi He, Christian Binek Jan 2009

Self-Assembly Of Magnetic Ni Nanoparticles Into 1d Arrays With Antiferromagnetic Order, Valery Bliznyuk, Srikanth Singamaneni, Sarbeswar Sahoo, Srinivas Polisetty, Xi He, Christian Binek

Christian Binek Publications

In this paper, we report on the magnetic properties of isolated nanoparticles and interacting nanochains formed by the self-assembly of Ni nanoparticles. The magnetic properties were studied using superconducting quantum interference device (SQUID) magnetometry and magnetic force microscopy (MFM). We demonstrate that single-domain Ni nanoparticles spontaneously form one-dimensional (1D) chains under the influence of an external magnetic field. Furthermore, such magnetic field-driven self-assembly in conjunction with surface templating produces regular arrays of 1D nanochains with antiferromagnetic intra-chain order. The antiferromagnetic order, which is in striking contrast to what is found for non-interacting nanoparticle assemblies within the chains, can be evidenced …

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Dipole-Induced, Thermally Stable Lamellar Structure By Polar Aromatic Silane, Jinyue Jiang, Ocelio V. Lima, Yong Pei, Xiao Cheng Zeng, Li Tan, Eric Forsythe Jan 2009

Dipole-Induced, Thermally Stable Lamellar Structure By Polar Aromatic Silane, Jinyue Jiang, Ocelio V. Lima, Yong Pei, Xiao Cheng Zeng, Li Tan, Eric Forsythe

Xiao Cheng Zeng Publications

Lamellar structures, consisting of alternating inorganic layers separated by organic moieties, have attracted much attention over a wide range of applications, such as polymer-clay composites, rheology control, and optoelectronic devices. Organosilanes are ideal candidates for such efforts due to their ability to self-assemble and the intrinsic hybrid configuration of organic/inorganic moieties. Yet, the main emphasis has been focused on alkylsilane, where an alkyl group is linked with a silane terminal, i.e., R-SiX3 (R is alkane and X can be halogen or alkoxy). Construction of stacked monolayers of alkylsilane through chemisorption is possible. The demonstrated pathway usually takes place after …

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Materials Design Of Half-Metallic Graphene And Graphene Nanoribbons, Menghao Wu, Xiaojun Wu, Yi Gao, Xiao Cheng Zeng Jan 2009

Materials Design Of Half-Metallic Graphene And Graphene Nanoribbons, Menghao Wu, Xiaojun Wu, Yi Gao, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

Through patterned chemical modification, we show that both graphene sheets and zigzag-edged graphene nanoribbons (ZGNRs) can be converted to half-metals as long as the unmodified carbon strip (or width of ZGNRs) is sufficiently wide. Periodically functionalized graphene can mimic electronic behavior of edge-modified ZGNRs as the edge-modified zigzag carbon chains effectively divide a graphene sheet into a series of identical ZGNRs.

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First-Principles Study Of Methane Dehydrogenation On A Bimetallic Cu/N(111) Surface, Wei An, Xiao Cheng Zeng, C. Heath Turner Jan 2009

First-Principles Study Of Methane Dehydrogenation On A Bimetallic Cu/N(111) Surface, Wei An, Xiao Cheng Zeng, C. Heath Turner

Xiao Cheng Zeng Publications

We present density-functional theory calculations of the dehydrogenation of methane and CHx (x = 1 – 3) on a Cu/Ni(111) surface, where Cu atoms are substituted on the Ni surface at a coverage of 1/4 monolayer.

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On The Phase Diagram Of Water With Density Functional Theory Potentials: The Melting Temperature Of Ice /H With The Perdew–Burke–Ernzerhof And Becke–Lee–Yang–Parr Functionals, Soohaeng Yoo, Xiao Cheng Zeng, Sotiris C. Xantheas Jan 2009

On The Phase Diagram Of Water With Density Functional Theory Potentials: The Melting Temperature Of Ice /H With The Perdew–Burke–Ernzerhof And Becke–Lee–Yang–Parr Functionals, Soohaeng Yoo, Xiao Cheng Zeng, Sotiris C. Xantheas

Xiao Cheng Zeng Publications

The melting temperature (Tm) of ice Ih was determined from constant enthalpy and pressure (NPH) Born–Oppenheimer molecular dynamics simulations to be 417±3 K for the Perdew–Burke– Ernzerhof and 411±4 K for the Becke–Lee–Yang–Parr density functionals using a coexisting ice (Ih)-liquid phase at constant pressures of P=2500 and 10 000 bar and a density p=1 g/cm3, respectively.

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Noncovalent Interactions In The Asymmetric Synthesis Of Rigid, Conjugated Helical Structures, Makoto Miyasaka, Maren Pink, Suchada Rajca, Andrzej Rajca Jan 2009

Noncovalent Interactions In The Asymmetric Synthesis Of Rigid, Conjugated Helical Structures, Makoto Miyasaka, Maren Pink, Suchada Rajca, Andrzej Rajca

Andrzej Rajca Publications

Helical supramolecular architecture, such as helical foldamers, supramolecular helicates and aggregates, helical molecules, macromolecules, and oligomers, is a fascinating topic of interest in chemistry and materials science. Although such supramolecular structures may provide advantages in the design of stimuli-responsive and functional materials, the weak nature of the noncovalent forces, as well as the dependency of the dynamic process on their local environments, may hinder their possible applications because of their limited structural stability and processibility. Stabilization of these supramolecular structures could be achieved by modification of the molecular backbone with specific functional groups that permit intramolecular cross-linking, in which covalent …

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Paleohydrology Of Kangerlussuaq (Søndre Strømfjord), West Greenland During The Last ~8,000 Years, Frank Aebly, Sherilyn C. Fritz Jan 2009

Paleohydrology Of Kangerlussuaq (Søndre Strømfjord), West Greenland During The Last ~8,000 Years, Frank Aebly, Sherilyn C. Fritz

Department of Earth and Atmospheric Sciences: Faculty Publications

Major fluctuations of hydroclimate in West Greenland are recorded in paleoshoreline terraces that encircle several lakes near Kangerlussuaq, Greenland (67°01’N, 50°40’W). Geomorphic and stratigraphic analyses were used to construct a lake-level curve for Hunde Sø, a large closed-basin lake in this region. Changes in lake volume associated with lake-level fluctuations were calculated, and a water-balance model was used to determine the primary factors influencing lake volume and the changes in those factors necessary to affect reconstructed lake-level change. Sensitivity tests suggest that mean annual precipitation and the relative proportion of summer versus winter precipitation are the primary climate drivers of …

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Can Information Systems Foster Emotional Intelligence? A Design Theory-Based Approach, Richard J. Burkhard, Thomas A. Horan, Brian N. Hilton, Michael Leih Jan 2009

Can Information Systems Foster Emotional Intelligence? A Design Theory-Based Approach, Richard J. Burkhard, Thomas A. Horan, Brian N. Hilton, Michael Leih

Journal of International Technology and Information Management

Researchers in Information Systems (IS) have conducted extensive research into various kinds of collaboration systems over the last twenty-five years. A parallel stream of inquiry in psychology and management has developed research in organizational Emotional Intelligence, which contributes to the effectiveness of group interactions by increasing cooperation and reducing conflict. Collaboration systems present a special opportunity to introduce soft management functions such as Emotional Intelligence because they are designed as an intelligent channel of interaction between group members. This research used an Information Systems Design Theory approach to guide the integration of Emotional Intelligence functions into collaboration systems. Two artifact …

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Pentral: Pattern Based Logic Language, Manuj Darbari, Abhay Kumar Srivastava, Sanjay Medhavi Jan 2009

Pentral: Pattern Based Logic Language, Manuj Darbari, Abhay Kumar Srivastava, Sanjay Medhavi

Journal of International Technology and Information Management

The article focuses on the urban traffic representation using patterns which are specifically developed for traffic situations. The framework PENTRAL (PEtri-Net TRAnsportation Language) provides conversion of these patterns into algebraic format. These formats are saved as an XML file following the three tier architecture of urban Traffic system.

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Machine Translation In A Multilingual Electronic Meeting, Milam Aiken, Mina Park Jan 2009

Machine Translation In A Multilingual Electronic Meeting, Milam Aiken, Mina Park

Journal of International Technology and Information Management

Electronic meetings can be more efficient and effective than traditional, oral discussions, but until only recently, groups with no common language could not benefit from machine translation. Although it is possible for linguists or other staff members using machines to translate comments during a multilingual discussion, the research presented here shows that this is not feasible for large groups speaking many languages. As a solution, we propose a fully automated multilingual meeting system, and an example of its use in a meeting with Chinese, Korean, and English comments shows its potential to reduce multinational communication barriers.

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Androgen-Stimulated Udp-Glucose Dehydrogenase Expression Limits Prostate Androgen Availability Without Impacting Hyaluronan Levels, Qin Wei, Robert Galbenus, Ashraf Raza, Ronald Cerny, Melanie A. Simpson Jan 2009

Androgen-Stimulated Udp-Glucose Dehydrogenase Expression Limits Prostate Androgen Availability Without Impacting Hyaluronan Levels, Qin Wei, Robert Galbenus, Ashraf Raza, Ronald Cerny, Melanie A. Simpson

Ronald Cerny Publications

UDP-glucose dehydrogenase (UGDH) oxidizes UDP-glucose to UDP-glucuronate, an essential precursor for production of hyaluronan (HA), proteoglycans, and xenobiotic glucuronides. High levels of HA turnover in prostate cancer are correlated with aggressive progression. UGDH expression is high in the normal prostate even though HA accumulation is virtually undetectable. Thus, its normal role in the prostate may be to provide precursors for glucuronosyltransferase enzymes, which inactivate and solubilize androgens by glucuronidation. In this report, we quantified androgen dependence of UGDH, glucuronosyltransferase, and HA synthase expression. Androgen dependent and independent human prostate cancer cell lines were used to test the effects of UGDH …

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Continuous And Smooth Potential Energy Surface For Conductorlike Screening Solvation Model Using Fixed Points With Variable Areas, Peifeng Su, Hui Li Jan 2009

Continuous And Smooth Potential Energy Surface For Conductorlike Screening Solvation Model Using Fixed Points With Variable Areas, Peifeng Su, Hui Li

Department of Chemistry: Faculty Publications

Rigorously continuous and smooth potential energy surfaces, as well as exact analytic gradients, are obtained for a conductorlike screening solvation model (CPCM, a variant of the general COSMO) with Hartree–Fock (RHF, ROHF, UHF, and MCSCF) and density functional theory (R-DFT, RO-DFT, and U-DFT) methods using a new tessellation scheme, fixed points with variable areas (FIXPVA). In FIXPVA, spheres centered at atoms are used to define the molecular cavity and surface. The surface of each sphere is divided into 60, 240, or 960 tesserae, which have positions fixed relative to the sphere center and areas scaled by switching functions of their …

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Smooth Potential Energy Surface For Cavitation, Dispersion, And Repulsion Free Energies In Polarizable Continuum Model, Yali Wang, Hui Li Jan 2009

Smooth Potential Energy Surface For Cavitation, Dispersion, And Repulsion Free Energies In Polarizable Continuum Model, Yali Wang, Hui Li

Department of Chemistry: Faculty Publications

The fixed points with variable areas [FIXPVA (Ref. 1)] tessellation scheme is used to obtain smooth potential energy surfaces for the cavitation Gcav, dispersion Gdis, and repulsion Grep free energies in the polarizable continuum model (PCM). It is shown that FIXPVA can reproduce the standard GEPOL (Ref. 4) results to within 1 kcal/mol.

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A New Peroxide Fragmentation: Efficient Chemical Generation Of 1O2 In Organic Media, Patrick Dussault, Prasanta Ghorai Jan 2009

A New Peroxide Fragmentation: Efficient Chemical Generation Of 1O2 In Organic Media, Patrick Dussault, Prasanta Ghorai

Department of Chemistry: Faculty Publications

Monoactivated derivatives of 1,1-dihydroperoxides undergo an unprecedented base-promoted fragmentation to efficiently generate singlet oxygen (1O2) in anhydrous organic solvents.

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A Multi-Step Nmr Screen For The Identification And Evaluation Of Chemical Leads For Drug Discovery, Kelly A. Mercier, Matthew D. Shortridge, Robert Powers Jan 2009

A Multi-Step Nmr Screen For The Identification And Evaluation Of Chemical Leads For Drug Discovery, Kelly A. Mercier, Matthew D. Shortridge, Robert Powers

Department of Chemistry: Faculty Publications

A multi-step NMR based screening assay is described for identifying and evaluating chemical leads for their ability to bind a target protein. The multi-step NMR assay provides structure-related information while being an integral part of a structure based drug discovery and design program. The fundamental principle of the multi-step NMR assay is to combine distinct 1D and 2D NMR techniques, in such a manner, that the inherent strengths and weakness associated with each technique is complementary to each other in the screen. By taking advantage of the combined strengths of 1D and 2D NMR experiments, it is possible to minimize …

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Anhydrous Fluoride Salts And Reagents And Methods For Their Production, Stephen G. Dimagno, Haoran Sun Jan 2009

Anhydrous Fluoride Salts And Reagents And Methods For Their Production, Stephen G. Dimagno, Haoran Sun

Department of Chemistry: Faculty Publications

Anhydrous organic fluoride salts and reagents prepared by a method comprising the nucleophilic Substitution of a fluorinated aromatic or fluorinated unsaturated organic compound with a salt having the formula: [QnM]x+Ax- in an inert polar, aprotic solvent; wherein M is an atom capable of supporting a formal positive charge, the n groups Q are independently varied organic moieties, n is an integer such that the [QnM] carries at least one formal positive charge, x is an integer defining the number of formal positive charge(s), +, carried by the [QnM], A- …

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Bess: BIofuel ENergy SYstems SImulator: Life Cycle Energy & Emissions Analysis Model For Corn-Ethanol Biofuel Production Systems -- User’S Guide For The Bess Model, Adam Liska, Haishun Yang, Daniel T. Walters, Kenneth Cassman, Terry Klopfenstein, Galen Erickson, Virgil R. Bremer, Richard K. Koelsch, Dan Kenney, Patrick Tracy Jan 2009

Bess: BIofuel ENergy SYstems SImulator: Life Cycle Energy & Emissions Analysis Model For Corn-Ethanol Biofuel Production Systems -- User’S Guide For The Bess Model, Adam Liska, Haishun Yang, Daniel T. Walters, Kenneth Cassman, Terry Klopfenstein, Galen Erickson, Virgil R. Bremer, Richard K. Koelsch, Dan Kenney, Patrick Tracy

Adam Liska Papers

The BESS model is a software tool to calculate the energy efficiency, greenhouse gas (GHG) emissions, and natural resource requirements of corn–to-ethanol biofuel production systems. The model provides a “cradle-to-grave” analysis of the production life cycle of biofuels from the creation of material inputs to finished products, producing an inventory of distributed GHG emissions from fossil fuels and a few key indirect emissions in the production life cycle. The model parameters can be set by the user to achieve the highest accuracy in evaluating a single corn-ethanol biorefinery and its surrounding feedstock crop production zone. The model equations and summary …

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Energy Gradients In Combined Fragment Molecular Orbital And Polarizable Continuum Model (Fmo/Pcm) Calculation, Hui Li, Dmitri G. Federov, Takeshi Nagata, Kazuo Kitaura, Jan H. Jensen, Mark S. Gordon Jan 2009

Energy Gradients In Combined Fragment Molecular Orbital And Polarizable Continuum Model (Fmo/Pcm) Calculation, Hui Li, Dmitri G. Federov, Takeshi Nagata, Kazuo Kitaura, Jan H. Jensen, Mark S. Gordon

Hui Li Publications

The analytic energy gradients for the combined fragment molecular orbital and polarizable continuum model (FMO/PCM) method are derived and implemented. Applications of FMO/PCM geometry optimization to polyalanine show that the structures obtained with the FMO/PCM method are very close to those obtained with the corresponding full ab initio PCM methods. FMO/PCM (RHF/6-31G* level) is used to optimize the solution structure of the 304-atom Trp-cage miniprotein and the result is in agreement with NMR experiments. The key factors determining the relative stability of the a-helix, b-turn and the extended form in solution are elucidated for polyalanine.

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Semiclassical Propagation Method For Tunneling Ionization, Ilya I. Fabrikant, Gordon A. Gallup Jan 2009

Semiclassical Propagation Method For Tunneling Ionization, Ilya I. Fabrikant, Gordon A. Gallup

Gordon Gallup Publications

We apply the semiclassical propagation technique to tunneling ionization in atomic and molecular systems. Semiclassical wave functions and the tunneling flux are calculated from the solution of the classical equations of motion in the complex time plane. We illustrate this method by rederiving the known result for the decay rate of a negative ion in a weak electric field. We then obtain numerical results for atomic hydrogen, H2+, H2, and Ar, and compare them with the results of the asymptotic [Ammosov-Delone-Krainov (ADK)] theory. The asymptotic theory gives surprisingly good results for the atomic and molecular …

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