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- Acetylcholine (1)
- Acetylcholine receptor (1)
- Acetylcholinesterase (1)
- Archaeglobus fulgidis (1)
- Butyrylcholinesterase (1)
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- Chemoselective reduction (1)
- Cobalt oxides (1)
- Diaphragm (1)
- Epitaxial films (1)
- Fumonisin; <i>Fusarium verticillioides</i>; mycotoxin; biosynthesis (1)
- Knockout mice (1)
- Magnesium (1)
- Methanol (1)
- Muscle tension (1)
- NMR (1)
- Protein AF2095 (1)
- Reagent (1)
- Resonance assignments (1)
- Rocksalt (1)
- Secondary structure (1)
- Spinel (1)
- Water adsorption (1)
Articles 1 - 23 of 23
Full-Text Articles in Physical Sciences and Mathematics
An Extension Of The Quasicontinuum Treatment Of Multiscale Solid Systems To Nonzero Temperature, Dennis J. Diestler, Z.-B. Wu, Xiao Cheng Zeng
An Extension Of The Quasicontinuum Treatment Of Multiscale Solid Systems To Nonzero Temperature, Dennis J. Diestler, Z.-B. Wu, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
Covering the solid lattice with a finite-element mesh produces a coarse-grained system of mesh nodes as pseudoatoms interacting through an effective potential energy that depends implicitly on the thermodynamic state. Use of the pseudoatomic Hamiltonian in a Monte Carlo simulation of the two-dimensional Lennard-Jones crystal yields equilibrium thermomechanical properties (e.g., isotropic stress) in excellent agreement with “exact” fully atomistic results.
Nanoscale Hydrophobic Interaction And Nanobubble Nucleation, T. Koishi, S. Yoo, K. Yasuoka, Xiao Cheng Zeng, T. Narumi, R. Susukita, A. Kawai, H. Furusawa, A. Suenaga, N. Okimoto, N. Futatsugi, T. Ebisuzaki
Nanoscale Hydrophobic Interaction And Nanobubble Nucleation, T. Koishi, S. Yoo, K. Yasuoka, Xiao Cheng Zeng, T. Narumi, R. Susukita, A. Kawai, H. Furusawa, A. Suenaga, N. Okimoto, N. Futatsugi, T. Ebisuzaki
Xiao Cheng Zeng Publications
We report large-scale atomistic simulation of midrange nanoscale hydrophobic interaction, manifested by the nucleation of nanobubble between nanometer-sized hydrophobes at constrained equilibrium. When the length scale of the hydrophobes is greater than 2 nm, the nanobubble formation shows hysteresis behavior resembling the first-order transition. Calculation of the potential of mean force versus interhydrophobe distance provides a quantitative measure of the strength of the nanoscale hydrophobic interaction.
Hybrid Atomistic-Coarse-Grained Treatment Of Thin-Film Lubrication. Ii, Z.-B. Wu, Dennis J. Diestler, Xiao Cheng Zeng
Hybrid Atomistic-Coarse-Grained Treatment Of Thin-Film Lubrication. Ii, Z.-B. Wu, Dennis J. Diestler, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
A new hybrid atomistic-coarse-grained (HACG) treatment of reversible processes in multiple-scale systems involving fluid-solid interfaces was tested through isothermal-isobaric Monte Carlo simulations of the quasistatic shearing of a model two-dimensional lubricated contact comprising two planar Lennard-Jones solid substrates that sandwich a softer Lennard-Jones film. Shear-stress profiles (plots of shear stress Tyx versus lateral displacement of the substrates) obtained by the HACG technique, which combines an atomistic description of the interfacial region with a continuum description of regions well removed from the interface, are compared with “exact” profiles (obtained by treating the whole system at the atomic scale) for a …
Melting Points And Thermal Expansivities Of Proton-Disordered Hexagonal Ice With Several Model Potentials, Yuji Koyama, Hideki Tanaka, Guangtu Gao, Xiao Cheng Zeng
Melting Points And Thermal Expansivities Of Proton-Disordered Hexagonal Ice With Several Model Potentials, Yuji Koyama, Hideki Tanaka, Guangtu Gao, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
A method of free energy calculation is proposed, which enables to cover a wide range of pressure and temperature. The free energies of proton-disordered hexagonal ice (ice Ih) and liquid water are calculated for the TIP4P [J. Chem. Phys. 79, 926 (1983)] model and the TIP5P @J. Chem. Phys. 112, 8910 (2000) model. From the calculated free energy curves, we determine the melting point of the proton-disordered hexagonal ice at 0.1 MPa (atmospheric pressure), 50 MPa, 100 MPa, and 200 MPa. The melting temperatures at atmospheric pressure for the TIP4P ice and the TIP5P ice are found to be about …
1H, 13C, And 15N Assignments For The Archaeglobus Fulgidis Protein Af2095, Robert Powers, Thomas B. Acton, Yi-Wen Chiang, P. K. Rajan, John R. Cort, Michael A. Kennedy, Jinfeng Liu, Lichung Ma, Burkhard Rost, Gaetano T. Montelione
1H, 13C, And 15N Assignments For The Archaeglobus Fulgidis Protein Af2095, Robert Powers, Thomas B. Acton, Yi-Wen Chiang, P. K. Rajan, John R. Cort, Michael A. Kennedy, Jinfeng Liu, Lichung Ma, Burkhard Rost, Gaetano T. Montelione
Robert Powers Publications
Structural genomics is providing a means to determine the molecular and cellular function for the vast amount of proteins in the Human proteome that lack any explicit experimental information by characterizing the complete range of protein folds (Montelione, 2001). The Northeast Structural Genomics Consortium (NESG; http://www.nesg.org/) is a pilot project funded by the National Institutes of Health Protein Structure Initiative, focusing on proteins from eukaryotic model organisms including humans. The thermophillic archaea Archaeglobus fulgidis AF2095 protein is an example of a protein of unknown biological function targeted for structural analysis by NESG. AF2095 belongs to the Pfam family PF01981 – …
Curtius Rearrangement And Wolff Homologation Of Functionalized Peroxides, Patrick Dussault, Chunping Xu
Curtius Rearrangement And Wolff Homologation Of Functionalized Peroxides, Patrick Dussault, Chunping Xu
Patrick Dussault Publications
The Curtius and Wolff rearrangements of peroxide-containing alkanoyl azides and diazoketones provide an efficient entry to peroxysubstituted amines, isocyanates, carbamates, and peroxyalkanoates.
Includes 6 pages of "Experimental/Supporting Information" not published with the printed journal edition, and previously available only online.
In Situ Enzymatic Screening (Ises) Of P,N-Ligands For Ni(0)- Mediated Asymmetric Intramolecular Allylic Amination, David B. Berkowitz, Weijun Shen, Gourhari Maiti
In Situ Enzymatic Screening (Ises) Of P,N-Ligands For Ni(0)- Mediated Asymmetric Intramolecular Allylic Amination, David B. Berkowitz, Weijun Shen, Gourhari Maiti
David Berkowitz Publications
An in situ enzymatic screening (ISES) approach to rapid catalyst evaluation recently pointed to Ni(0) as a new candidate transition metal for intramolecular allylic amination. This led to further exploration of chiral bidentate phosphine ligands for such transformations. Herein, a variety of P,N-ligands are examined for this Ni(0)-chemistry, using a model reaction leading into the vinylglycinol scaffold. On the one hand, an N,N-bis(2-diphenylphosphinoethyl)alkylamine (‘PNP’) ligand proved to be the fastest ligand yet seen for this Ni(0)-transformation. On the other, phosphinooxazoline (PHOX) ligands of the Pfaltz–Helmchen– Williams variety gave the highest enantioselectivities (up to 51% ee) among P,N-ligands …
Surface Composition And Structure Of Co3O4(110) And The Effect Of Impurity Segregation, S.C. Petitto, Marjorie Langell
Surface Composition And Structure Of Co3O4(110) And The Effect Of Impurity Segregation, S.C. Petitto, Marjorie Langell
Marjorie A. Langell Publications
The Co3O4 (110) single crystal surface has been characterized by low energy electron diffraction (LEED), Auger electron spectroscopy, and x-ray photoelectron spectroscopy (XPS). LEED analysis of the clean Co3O4 (110) spinel surface shows a well-ordered pattern with sharp diffraction features. The XPS spectra are consistent with stoichiometric Co3O4 as determined by the concentration ratio of oxygen to cobalt (CO /CCo) and spectral peak shape. In particular, the cobalt 2p XPS spectra are characteristic of the spinel structure with Co3+ occupying octahedral sites and Co2+ …
Evidence That Hsp90 Is Involved In The Altered Interactions Of Acanthamoeba Castellanii Variants With Bacteria, Ling Yan, Ronald Cerny, Jeffrey D. Cirillo
Evidence That Hsp90 Is Involved In The Altered Interactions Of Acanthamoeba Castellanii Variants With Bacteria, Ling Yan, Ronald Cerny, Jeffrey D. Cirillo
Ronald Cerny Publications
There are many similarities between the interactions of environmental protozoa with pathogenic bacterial species and those observed in mammalian macrophages. Since single-celled protozoa predate mammalian hosts, it is likely that interactions in environmental biofilms have selected for many of the bacterial virulence mechanisms responsible for human disease. In order to better understand bacterial-phagocyte interactions, we developed a selection for Acanthamoeba castellanii variants that are more resistant to killing by bacterial pathogens. We identified four amoebal clones that display decreased phagocytosis of bacteria but no difference in uptake of latex beads compared to wild-type amoebae. These amoebal variants display differences in …
Structures And Stability Of Medium Silicon Clusters. Ii. Ab Initio Molecular Orbital Calculations Of Si12–Si20, X.-L. Zhu, Xiao Cheng Zeng, Y.A. Lei, B. Pan
Structures And Stability Of Medium Silicon Clusters. Ii. Ab Initio Molecular Orbital Calculations Of Si12–Si20, X.-L. Zhu, Xiao Cheng Zeng, Y.A. Lei, B. Pan
Xiao Cheng Zeng Publications
Ab initio all-electron molecular-orbital calculations are carried out to study the structures and relative stability of low-energy silicon clusters (Sin , n=12– 20). Selected geometric isomers include those predicted by Ho et al. [Nature (London) 392, 582 (1998)] based on an unbiased search with tight-binding/genetic algorithm, as well as those found by Rata et al. [Phys. Rev. Lett. 85, 546 (2000)] based on density-functional tight-binding/single-parent evolution algorithm. These geometric isomers are optimized at the Møller–Plesset (MP2) MP2/6-31G(d) level. The single-point energy at the coupled-cluster single and double substitutions (including triple excitations) [CCSD(T)] CCSD(T)/6-31G(d …
Determining The Biosynthetic Sequence In The Early Steps Of The Fumonisin Pathway By Use Of Three Gene-Disruption Mutants Of Fusarium Verticillioides, Ravi S. Bojja, Ronald Cerny, Robert H. Proctor, Liangcheng Du
Determining The Biosynthetic Sequence In The Early Steps Of The Fumonisin Pathway By Use Of Three Gene-Disruption Mutants Of Fusarium Verticillioides, Ravi S. Bojja, Ronald Cerny, Robert H. Proctor, Liangcheng Du
Ronald Cerny Publications
Fumonisins are polyketide-derived mycotoxins produced by Fusarium verticillioides, a fungal pathogen of corn plants. Although a gene cluster for the biosynthesis of fumonisins has been cloned, the biosynthetic pathway is still not clear. We have used three gene-disrupted mutants, designated ΔFUM1, ΔFUM6, and ΔFUM8, to study the early steps of the pathway. Fumonisins were not produced in single-strain cultures of the ΔFUM1, ΔFUM6, and ΔFUM8 mutants. However, fumonisins were produced by ΔFUM1 or ΔFUM8 mutants when they were cocultured with the ΔFUM6 mutant. No fumonisins were produced when the ΔFUM1 and ΔFUM8 mutants were cocultured. These results suggest that …
In Situ Magnetoresistance Of Ni Nanocontacts, C-S Yang, Chunjuan Zhang, Jody G. Redepenning, Bernard Doudin
In Situ Magnetoresistance Of Ni Nanocontacts, C-S Yang, Chunjuan Zhang, Jody G. Redepenning, Bernard Doudin
Chemistry Department: Faculty Publications
Magnetoresistance properties of Ni nanocontacts in the ballistic quantum regime are investigated in situ during closure and opening of electrochemically grown planar electrodes. The magnitude of conductance change when sweeping the magnetic field is of the order of the quantum conductance e2/h for conductance values spanning 1–100 quanta. The relative orientation of electric current and applied magnetic field changes the magnetoresistance sign, with symmetry properties reminiscent of bulk anisotropy magnetoresistance. Ex situ investigations of samples of higher conductance values, of the order of 1000 quanta, unambiguously show the analogy with bulk anisotropy magnetoresistance.
Hybrid Atomistic-Coarse-Grained Treatment Of Thin-Film Lubrication. I, Z.-B. Wu, Dennis J. Diestler, Ruqiang Feng, Xiao Cheng Zeng
Hybrid Atomistic-Coarse-Grained Treatment Of Thin-Film Lubrication. I, Z.-B. Wu, Dennis J. Diestler, Ruqiang Feng, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
A technique that melds an atomistic description of the interfacial region with a coarse-grained description of the far regions of the solid substrates is presented and applied to a two-dimensional model contact consisting of planar solid substrates separated by a monolayer fluid film. The hybrid method yields results in excellent agreement with the “exact” (i.e., fully atomistic) results. The importance of a proper accounting for the elastic response of the substrates, which is reliably and efficiently accomplished through coarse-graining of the far regions, is demonstrated.
Fum3p, A 2-Ketoglutarate-Dependent Dioxygenase Required For C-5 Hydroxylation Of Fumonisins In Fusarium Verticillioides, Yousong Ding, Ravi S. Bojja, Liangcheng Du
Fum3p, A 2-Ketoglutarate-Dependent Dioxygenase Required For C-5 Hydroxylation Of Fumonisins In Fusarium Verticillioides, Yousong Ding, Ravi S. Bojja, Liangcheng Du
Liangcheng Du Publications
Fumonisins are polyketide-derived mycotoxins produced by several agriculturally important Fusarium species. The B series fumonisins, FB1, FB2, FB3, and FB4, are fumonisins produced by wild-type Fusarium verticillioides strains, differing in the number and location of hydroxyl groups attached to the carbon backbone. We characterized the protein encoded by FUM3, a gene in the fumonisin biosynthetic gene cluster. The 33-kDa FUM3 protein (Fum3p) was heterologously expressed and purified from Saccharomyces cerevisiae. Yeast cells expressing the Fum3p converted FB3 to FB1, indicating that Fum3p catalyzes the C-5 hydroxylation of fumonisins. …
Magnesium/Methanol: An Effective Reducing Agent For Peroxides , Peng Dai, Patrick Dussault, Tony K. Trullinger
Magnesium/Methanol: An Effective Reducing Agent For Peroxides , Peng Dai, Patrick Dussault, Tony K. Trullinger
Chemistry Department: Faculty Publications
Magnesium in methanol is an effective reagent for the chemoselective reduction of peroxides, including ozonides. Mg/MeOH is significantly more reactive than Me2S or PPh3 and somewhat more reactive than Zn/HOAc
The Creation Of Organic And Biological Nanostructures At Surfaces Using Scanning Probe Nanolithography, B. L. Weeks, Chin Li Cheung, J. J. De Yoreo
The Creation Of Organic And Biological Nanostructures At Surfaces Using Scanning Probe Nanolithography, B. L. Weeks, Chin Li Cheung, J. J. De Yoreo
Barry Chin Li Cheung Publications
As the size of microelectronic devices continues to shrink and the desire to build in hierarchical structures of organic and biological materials grows, control of the chemistry and structure of materials at the molecular level will become increasingly important. Conventional lithographic techniques to pattern polymeric thin films are beginning to reach their resolution limit and several alternative "bottom-up" strategies have emerged that use the scanning probe microscope to manipulate matter at the atomic or molecular scale. Of these new scanning probe nanolithography (SPN) techniques, dip-pen nanolithography (DPN) [I] and scanning probe nanografting (SNG) [2] are particularly promising.
The DPN methodology …
Orientation And Bonding Of Biphenyldimethyldithiol, A. N. Caruso, R. Rajesh, Gordon A. Gallup, Jody G. Redepenning, Peter A. Dowben
Orientation And Bonding Of Biphenyldimethyldithiol, A. N. Caruso, R. Rajesh, Gordon A. Gallup, Jody G. Redepenning, Peter A. Dowben
Chemistry Department: Faculty Publications
The molecular orbitals of 1, 1′-biphenyl-4,4′-dimethyldithiol (HS– CH2–C6H4–C6H4–CH2–SH) are identified from combined photoemission and inverse photoemission studies and compared with theory for several different surfaces, molecular conformations and molecular orientations. The preferential molecular orientations of biphenyldimethyldithiol, on both Au(111) and polycrystalline Co, are identified from polarization resolved photoemission studies. Two different molecular orientations are adopted by biphenyldimethyldithiol on gold depending on adsorption conditions. Biphenyldimethyldithiol is observed to bond more strongly to cobalt than gold surfaces.
Cobalt Oxide Surface Chemistry: The Interaction Of Coo(1 0 0), Co3O4(1 1 0), And Co3O4(1 1 1) With Oxygen And Water, Sarah C. Petitto, Erin M. Marsh, Gregory A. Carson, Marjorie Langell
Cobalt Oxide Surface Chemistry: The Interaction Of Coo(1 0 0), Co3O4(1 1 0), And Co3O4(1 1 1) With Oxygen And Water, Sarah C. Petitto, Erin M. Marsh, Gregory A. Carson, Marjorie Langell
Marjorie A. Langell Publications
Cobalt oxides comprise two readily accessible cation oxidation states: Co2+ and Co3+, which are thermodynamically competitive under common ambient conditions, and redox mechanisms connecting the two states are largely responsible for their success in partial oxidation catalysis. In our studies, CoO(1 0 0), Co3O4(1 1 0), and Co3O4(1 1 1) single crystal substrates have been investigated with X-ray photoelectron spectroscopy (XPS), high-resolution electron energy loss spectroscopy (HREELS), and low energy electron diffraction (LEED) for their surface reactivity toward O3 and H2O and for their stability under …
The Melting Lines Of Model Silicon Calculated From Coexisting Solid–Liquid Phases, S. Yoo, Xiao Cheng Zeng, James R. Morris
The Melting Lines Of Model Silicon Calculated From Coexisting Solid–Liquid Phases, S. Yoo, Xiao Cheng Zeng, James R. Morris
Xiao Cheng Zeng Publications
The melting line is an important thermodynamic property of materials and can be calculated via computer simulation, given the intermolecular potential for the materials. Conventionally, the free-energy method has been mainly employed to calculate the melting line. Alternatives to the free-energy method for calculating the melting line include simulation of the solid-liquid coexistence and nonequilibrium molecular dynamics (MD) method. Recently, one of us (Morris) and Song reported a detailed simulation procedure to calculate the melting line of the Lennard-Jones system. Specifically, the MD simulation consists of a preparation run and a production run. In the preparation run, the liquid and …
Optimization Of Conditions For Studies Of Protein Unfolding By Hydrogen Exchange/Mass Spectrometry, A.S. Raza, David L. Smith
Optimization Of Conditions For Studies Of Protein Unfolding By Hydrogen Exchange/Mass Spectrometry, A.S. Raza, David L. Smith
Chemistry Department: Faculty Publications
Understanding the forces driving protein folding and aggregation is an essential step in developing means for controlling these important processes. Amide hydrogen exchange, coupled with mass spectrometry, has become an important method for studying protein unfolding and refolding. To extend procedures developed to study unfolding of relatively soluble proteins to less soluble, aggregation-prone proteins requires special considerations. This publication describes a general strategy developed using yeast transaldolase, which aggregates easily under conditions required to study its unfolding. Results presented here show that reducing the protein concentration to the nanomolar range is essential for managing aggregation of transaldolase. In addition, the …
Reduced Acetylcholine Receptor Density, Morphological Remodeling, And Butyrylcholinesterase Activity Can Sustain Muscle Function In Acetylcholinesterase Knockout Mice, Michael Adler, Heather A. Manley, Angela L. Purcell, Sharad S. Deshpande, Tracey A. Hamilton, Robert K. Kan, George Oyler, Oksana Lockridge, Ellen G. Duysen, Robert E. Sheridan
Reduced Acetylcholine Receptor Density, Morphological Remodeling, And Butyrylcholinesterase Activity Can Sustain Muscle Function In Acetylcholinesterase Knockout Mice, Michael Adler, Heather A. Manley, Angela L. Purcell, Sharad S. Deshpande, Tracey A. Hamilton, Robert K. Kan, George Oyler, Oksana Lockridge, Ellen G. Duysen, Robert E. Sheridan
US Army Research
The vertebrate neuromuscular junction is designed for rapid transmission of excitatory signals for initiation of muscle contraction.5 Among the features responsible for the high throughput of this synapse are the close proximity of the presynaptic and postsynaptic membranes,10 the direct coupling of acetylcholine (ACh) binding to the opening of the ion channel associated with the nicotinic acetylcholine receptor (nAChR),27 the brief open time of this channel,21,27 and the presence of cholinesterase (ChE) for hydrolysis of ACh.21,30 At the endplate, there are two distinct ChEs for transmitter hydrolysis: acetylcholinesterase (EC 3.1.1.7, AChE) and butyrylcholinesterase (EC 3.1.1.8, BChE).33 Both enzymes can …
Metallic Single-Walled Silicon Nanotubes, Jaeil Bai, Xiao Cheng Zeng, Hideki Tanaka, J. Y. Zeng
Metallic Single-Walled Silicon Nanotubes, Jaeil Bai, Xiao Cheng Zeng, Hideki Tanaka, J. Y. Zeng
Xiao Cheng Zeng Publications
Atomistic computer-simulation evidences are presented for the
possible existence of one-dimensional silicon nanostructures: the
square, pentagonal, and hexagonal single-walled silicon nanotubes
(SWSNTs). The local geometric structure of the SWSNTs
differs from the local tetrahedral structure of cubic diamond
silicon, although the coordination number of atoms of the SWSNTs
is still fourfold. Ab initio calculations show that the SWSNTs
are locally stable in vacuum and have zero band gap, suggesting
that the SWSNTs are possibly metals rather than wide-gap
semiconductors.
Analysis Of Free Analyte Fractions By Rapid Affinity Chromatography, David S. Hage, William A. Clarke
Analysis Of Free Analyte Fractions By Rapid Affinity Chromatography, David S. Hage, William A. Clarke
Chemistry Department: Faculty Publications
The invention is generally directed toward an analytical method to determine the concentration of the free analyte fraction in a sample. More particularly, the method encompasses applying a sample comprising a free and bound analyte fraction to an affinity column capable of selectively extracting the free fraction in the millisecond time domain. The signal generated by the free fraction is then quantified by standard analytical detection techniques. The concentration of the free fraction may then be determined by comparison of its signal with that of a calibration curve depicting the signal of known concentration of the same analyte.