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Articles 1 - 23 of 23
Full-Text Articles in Physical Sciences and Mathematics
Computational Study Of Vibrational Qubits In Anharmonic Linear Ion Traps, Lei Wang
Computational Study Of Vibrational Qubits In Anharmonic Linear Ion Traps, Lei Wang
Dr Lei Wang
A string of cold ions confined in a linear trap represents a man-made quantum object with a broad range of applications in atomic and molecular spectroscopy, such as high-precision measurement of atomic properties. An efficient isolation from the environment guarantees excellent coherent properties of such systems and makes them suitable for practical realization of the quantum information processing. The pioneering theoretical [Cirac and Zoller] and experimental [Wineland and Monroe] work in 1990s resulted in the explosive expansion of this field during the last decade. In this dissertation an alternative new method for controlling the quantized motional/vibrational states of ions in …
36 Degrees Step Size Of Proton-Driven C-Ring Rotation In Fof1-Atp Synthase, Monika Düser, Nawid Zarrabi, Daniel Cipriano, Stefan Ernst, Gary Glick, Stanley Dunn, Michael Börsch
36 Degrees Step Size Of Proton-Driven C-Ring Rotation In Fof1-Atp Synthase, Monika Düser, Nawid Zarrabi, Daniel Cipriano, Stefan Ernst, Gary Glick, Stanley Dunn, Michael Börsch
Stanley D Dunn
Synthesis of adenosine triphosphate ATP, the 'biological energy currency', is accomplished by F(o)F(1)-ATP synthase. In the plasma membrane of Escherichia coli, proton-driven rotation of a ring of 10 c subunits in the F(o) motor powers catalysis in the F(1) motor. Although F(1) uses 120 degrees stepping during ATP synthesis, models of F(o) predict either an incremental rotation of c subunits in 36 degrees steps or larger step sizes comprising several fast substeps. Using single-molecule fluorescence resonance energy transfer, we provide the first experimental determination of a 36 degrees sequential stepping mode of the c-ring during ATP synthesis.
A Dipolar Coupling Based Strategy For Simultaneous Resonance Assignment And Structure Determination Of Protein Backbones, Fang Tian, Homayoun Valafar, James Prestegard
A Dipolar Coupling Based Strategy For Simultaneous Resonance Assignment And Structure Determination Of Protein Backbones, Fang Tian, Homayoun Valafar, James Prestegard
Homayoun Valafar
A new approach for simultaneous protein backbone resonance assignment and structure determination by NMR is introduced. This approach relies on recent advances in high-resolution NMR spectroscopy that allow observation of anisotropic interactions, such as dipolar couplings, from proteins partially aligned in field ordered media. Residual dipolar couplings are used for both geometric information and a filter in the assembly of residues in a sequential manner. Experimental data were collected in less than one week on a small redox protein, rubredoxin, that was 15N enriched but not enriched above 1% natural abundance in 13C. Given the acceleration possible with partial 13C …
Re-Introduction Of Transmembrane Serine Residues Reduce The Minimum Pore Diameter Of Channelrhodopsin-2, Robert Dempski, Ryan Richards
Re-Introduction Of Transmembrane Serine Residues Reduce The Minimum Pore Diameter Of Channelrhodopsin-2, Robert Dempski, Ryan Richards
Robert E. Dempski
Channelrhodopsin-2 (ChR2) is a microbial-type rhodopsin found in the green algae Chlamydomonas reinhardtii. Under physiological conditions, ChR2 is an inwardly rectifying cation channel that permeates a wide range of mono- and divalent cations. Although this protein shares a high sequence homology with other microbial-type rhodopsins, which are ion pumps, ChR2 is an ion channel. A sequence alignment of ChR2 with bacteriorhodopsin, a proton pump, reveals that ChR2 lacks specific motifs and residues, such as serine and threonine, known to contribute to non-covalent interactions within transmembrane domains. We hypothesized that reintroduction of the eight transmembrane serine residues present in bacteriorhodopsin, but …
Structural Insights Into Neuronal K+ Channel-Calmodulin Complexes, Karen Mruk, Shivender Shandilya, Robert Blaustein, Celia Schiffer, William Kobertz
Structural Insights Into Neuronal K+ Channel-Calmodulin Complexes, Karen Mruk, Shivender Shandilya, Robert Blaustein, Celia Schiffer, William Kobertz
Celia A. Schiffer
Calmodulin (CaM) is a ubiquitous intracellular calcium sensor that directly binds to and modulates a wide variety of ion channels. Despite the large repository of high-resolution structures of CaM bound to peptide fragments derived from ion channels, there is no structural information about CaM bound to a fully folded ion channel at the plasma membrane. To determine the location of CaM docked to a functioning KCNQ K(+) channel, we developed an intracellular tethered blocker approach to measure distances between CaM residues and the ion-conducting pathway. Combining these distance restraints with structural bioinformatics, we generated an archetypal quaternary structural model of …
A Reduced Model Of Cavitation Physics For Use In Sonochemistry, Brian Storey, Andrew Szeri
A Reduced Model Of Cavitation Physics For Use In Sonochemistry, Brian Storey, Andrew Szeri
Brian Storey
Sonochemistry involves focusing acoustic energy through cavitation bubbles to increase chemical activity. The violent bubble collapses lead to temperatures of several thousand kelvin, which drive chemical reactions. In previous work, we gave a detailed computational model of a single bubble collapse, taking into account phase change, mass diffusion, heat diffusion and chemical reactions. All of these phenomena are important in determining the conditions at collapse. The present work involves development of a much simpler model that includes all the physics relevant to the determination of the reaction products. Comparisons with the more detailed computations are made; the reduced model is …
Water Vapour, Sonoluminescence And Sonochemistry, Brian Storey, Andrew Szeri
Water Vapour, Sonoluminescence And Sonochemistry, Brian Storey, Andrew Szeri
Brian Storey
Sonoluminescence is the production of light from acoustically forced bubbles; sonochemistry is a related chemical processing technique. The two phenomena share a sensitive dependence on the liquid phase. The present work is an investigation of the fate and consequences of water vapour in the interior of strongly forced argon micro–bubbles. Due to the extreme nonlinearity of the volume oscillations, excess water vapour is trapped in the bubble during a rapid inertial collapse. Water vapour is prevented from exiting by relatively slow diffusion and non–equilibrium condensation at the bubble wall. By reducing the compression heating of the mixture and through primarily …
Dynamical Signature Of The Mott-Hubbard Transition In Ni(S,Se)(2), Yevgeniya Zastavker, Anke Husmann, Deborah Jin, Thomas Rosenbaum, X Yao, J Honig
Dynamical Signature Of The Mott-Hubbard Transition In Ni(S,Se)(2), Yevgeniya Zastavker, Anke Husmann, Deborah Jin, Thomas Rosenbaum, X Yao, J Honig
Yevgeniya V. Zastavker
The transition metal chalcogenide Ni(S,Se)2 is one of the few highly correlated, Mott-Hubbard systems without a strong first-order structural distortion that normally cuts off the critical behavior at the metal-insulator transition. The zero-temperature (T) transition was tuned with pressure, and significant deviations were found near the quantum critical point from the usual T1/2 behavior of the conductivity characteristic of electron-electron interactions in the presence of disorder. The transport data for pressure and temperature below 1 kelvin could be collapsed onto a universal scaling curve.
The Effect Of Frictional And Adhesion Forces Attributed To Slurry Particles On The Surface Quality Of Polished Copper, Yi-Koan Hong, Ja-Hyung Han, Tae-Gon Kim, Jin-Goo Park, Ahmed Busnaina
The Effect Of Frictional And Adhesion Forces Attributed To Slurry Particles On The Surface Quality Of Polished Copper, Yi-Koan Hong, Ja-Hyung Han, Tae-Gon Kim, Jin-Goo Park, Ahmed Busnaina
Jin-Goo Park
The effect of frictional and adhesion forces attributed to slurry particles on the quality of copper surfaces was experimentally investigated during copper chemical mechanical planarization process. The highest frictional force of 9 Kgf and adhesion force of 5.83 nN were observed in a deionized water-based alumina slurry. On the other hand, the smallest frictional force of 4 Kgf and adhesion force of 0.38 nN were measured in an alumina slurry containing citric acid. However, frictional (6 Kgf) and adhesion (1 nN) forces of silica particles in the slurry were not significantly changed regardless of the addition of citric acid. These …
Iron (Iii) Tosylate Catalyzed Synthesis Of Acylals (1,1-Diesters) From Aromatic Aldehydes, Ram Mohan, Anna Nord, '13
Iron (Iii) Tosylate Catalyzed Synthesis Of Acylals (1,1-Diesters) From Aromatic Aldehydes, Ram Mohan, Anna Nord, '13
Ram S. Mohan
No abstract provided.
Iron (Iii) Tosylate Catalyzed Synthesis Of Dihydropyrimidiones And Dihydropyrmidinothiones Via The Biginelli Reaction, Ram Mohan, Jacob Starcevich, '13, Thomas Laughlin, '14
Iron (Iii) Tosylate Catalyzed Synthesis Of Dihydropyrimidiones And Dihydropyrmidinothiones Via The Biginelli Reaction, Ram Mohan, Jacob Starcevich, '13, Thomas Laughlin, '14
Ram S. Mohan
No abstract provided.
The Development Of A Novel Therapeutic For The Treatment Of Sickle Cell Disease, Brian Brennan, Cody Wynn, '14
The Development Of A Novel Therapeutic For The Treatment Of Sickle Cell Disease, Brian Brennan, Cody Wynn, '14
Brian B. Brennan
No abstract provided.
Iron (Iii) Tosylate Catalyzed Synthesis Of Dihydrobenzopyrans, Ram Mohan, Stephen Whitfield, '14
Iron (Iii) Tosylate Catalyzed Synthesis Of Dihydrobenzopyrans, Ram Mohan, Stephen Whitfield, '14
Ram S. Mohan
No abstract provided.
Bismuth (Iii) Triflate Catalyzed Synthesis Of Homoallyl Allyl Ethers And Their Reactions, Ram Mohan, Brendan O'Donnell, '14
Bismuth (Iii) Triflate Catalyzed Synthesis Of Homoallyl Allyl Ethers And Their Reactions, Ram Mohan, Brendan O'Donnell, '14
Ram S. Mohan
No abstract provided.
Iron (Iii) Tosylate Catalyzed Acylation Of Alcohols And Phenols, Ram Mohan, Neil Baldwin, '13
Iron (Iii) Tosylate Catalyzed Acylation Of Alcohols And Phenols, Ram Mohan, Neil Baldwin, '13
Ram S. Mohan
No abstract provided.
Cuprocleav-1, A First Generation Photocage For Cu+, Shawn Burdette, Hannah Mbatia, H.M.Dhammika Bandara
Cuprocleav-1, A First Generation Photocage For Cu+, Shawn Burdette, Hannah Mbatia, H.M.Dhammika Bandara
Shawn C. Burdette
By utilizing thioether ligands, CuproCleav-1 stabilizes Cu+ complexes in aqueous solution and releases the guest metal ion upon photolysis of the nitrobenzyl group. The photocage has an apparent Kd of 54 pM for Cu+, and metal ion release has been demonstrated using the fluorescent sensor CS1.
Quantifying Factors That Influence Metal Ion Release In Photocaged Complexes Using Zincast Derivatives, Shawn Burdette
Quantifying Factors That Influence Metal Ion Release In Photocaged Complexes Using Zincast Derivatives, Shawn Burdette
Shawn C. Burdette
Two generations of nitrobenzhydrol-based photocages for Zn2+ have been prepared and characterized. The first series includes the tridentate ZinCast-1 utilizes a bis-pyridin-2-ylmethyl-aniline ligand that forms a 5,5-chelate ring upon metal binding. The related photocages ZinCast-2 with a N-[2-(pyridine-2-yl)ethyl]-N-(pyridine-2-ylmethyl)aniline (5,6-chelate ring) and ZinCast-3 with a N,N-bis[2-(pyridine-2-yl)ethyl]aniline (6,6-chelate ring) were synthesized for comparative studies. The complexes formed by the ions Cu2+, Zn2+ and Cd2+ with three ZinCast and their photoproducts (ZinUnc) were interrogated by UV-Vis spectroscopy. The studies indicate that ZinCast-1 forms complexes of the highest stability and ZinCast-3 exhibits the most significant changes in metal affinity upon uncaging. These results suggest …
The Synthesis And Biological Evaluation Of Tamandarin B Analogs, Kenneth Lassen
The Synthesis And Biological Evaluation Of Tamandarin B Analogs, Kenneth Lassen
Kenneth Lassen
The tamandarin and didemnins are a class of cyclodepsipeptides that have shown a wide range of biological activity. The didemnins have demonstrated antitumor, antiviral and immunosuppressive activity at low nano- and femtomolar levels. Didemnin B was the first marine natural product to enter clinical trials in humans in the United States. The structures of tamandarins A and B were reported in 2000 and possess almost identical structure and biological activity to didemnin B. These compounds have shown impressive biological activity and some progress has been made in establishing structure-activity relationships. However, their molecular mechanism of action is still unclear. The …
The Molecular Determinants Of The Zinc Transporter, Hzip4, Robert Dempski, Sagar Antala, Tuong-Vi Nguyen
The Molecular Determinants Of The Zinc Transporter, Hzip4, Robert Dempski, Sagar Antala, Tuong-Vi Nguyen
Robert E. Dempski
Zinc is an essential micronutrient which is required for the function of hundreds of cellular enzymes. In addition, zinc is the second most abundant transition metal found in biological systems (iron is most abundant). However, the concentration of free zinc is nano to picomolar since most zinc is bound to proteins. This makes investigating the mechanism of zinc transport across the plasma membrane a challenge. Our interest has been to elucidate the mechanism of zinc transport mediated by one member of the ZIP family of proteins, hZIP4.
Beyond Cell Penetrating Peptides: Designed Molecular Transporters, Paul Wender, Christina Cooley, Erika Geihe
Beyond Cell Penetrating Peptides: Designed Molecular Transporters, Paul Wender, Christina Cooley, Erika Geihe
Christina B Cooley
Inspired originally by peptides that traverse biological barriers, research on molecular transporters has since identified the key structural requirements that govern cellular entry, leading to new, significantly more effective and more readily available agents. These new drug delivery systems enable or enhance cellular and tissue uptake, can be targeted and provide numerous additional advantages of significance in imaging, diagnostics and therapy.
C60 Oxide As A Key Component Of Aqueous C60 Colloidal Suspensions, Befrika Murdianti, Joshua Damron, Martha Hilburn, Randall Maples, Rangika Hikkaduwa Koralege, Sathish Kuriyavar, Kevin Ausman
C60 Oxide As A Key Component Of Aqueous C60 Colloidal Suspensions, Befrika Murdianti, Joshua Damron, Martha Hilburn, Randall Maples, Rangika Hikkaduwa Koralege, Sathish Kuriyavar, Kevin Ausman
Kevin D. Ausman
Stable aqueous fullerene colloidal suspensions (nC60) are demonstrated to rely on the [6,6]-closed epoxide derivative of the fullerene (C60O) for stability. This derivative is present, though often unrecognized, in small quantities in nearly all C60 starting materials due to a reaction with air. The low-yield formation of nC60 from organic solvent solutions results from a preferential partitioning and thus enrichment of C60O in the colloidal particles. This partitioning is significantly retarded in the nC60 synthesis method that does not involve organic solvent solutions: long-term stirring in water. Instead, this method relies on trace levels of ozone in the ambient atmosphere …
Nanoscale Toughness And Behavior Of Graphene/Epoxy Interfaces, Nima Rahbar, Hossein Salahshoor
Nanoscale Toughness And Behavior Of Graphene/Epoxy Interfaces, Nima Rahbar, Hossein Salahshoor
Nima Rahbar
Atomistic simulations are performed to investigate the nano-scale interfacial fracture toughness between graphene and epoxy. Nano-mechanical properties of graphene and epoxy are initially studied using molecular dynamics simulations. A novel method is suggested to accurately model the behavior of the graphen/epoxy interface during the curing process of the epoxy as a function of temperature. The computed interfacial fracture energy is computed at about 0.203 J/m2, which is in good agreement with available experimental data. It is also shown that the adhesion between cured epoxy and graphene layer increases the pre-existing waviness of the 2-dimensional graphene sheet in a 3-dimensional space. …
Environmentally Friendly Organic Synthesis Using Bismuth(Iii) Compounds, Ram Mohan, Scott Krabbe
Environmentally Friendly Organic Synthesis Using Bismuth(Iii) Compounds, Ram Mohan, Scott Krabbe
Ram S. Mohan
Abstract With increasing environmental concerns, the need for environmentally friendly organic synthesis has gained increased importance. In this regard, bismuth (III) compounds are especially attractive as “green” reagents and catalysts for organic synthesis. Bismuth(III) compounds are remarkably nontoxic, relatively air and moisture stable, and easy to handle. The contributions from our laboratory in the last 5 years in the field of applications of bismuth(III) compounds as catalysts are presented.