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Sample records for reveals noncovalently bound

  1. Crystal Structure of the Dithiol Oxidase DsbA Enzyme from Proteus Mirabilis Bound Non-covalently to an Active Site Peptide Ligand

    Science.gov (United States)

    Kurth, Fabian; Duprez, Wilko; Premkumar, Lakshmanane; Schembri, Mark A.; Fairlie, David P.; Martin, Jennifer L.

    2014-01-01

    The disulfide bond forming DsbA enzymes and their DsbB interaction partners are attractive targets for development of antivirulence drugs because both are essential for virulence factor assembly in Gram-negative pathogens. Here we characterize PmDsbA from Proteus mirabilis, a bacterial pathogen increasingly associated with multidrug resistance. PmDsbA exhibits the characteristic properties of a DsbA, including an oxidizing potential, destabilizing disulfide, acidic active site cysteine, and dithiol oxidase catalytic activity. We evaluated a peptide, PWATCDS, derived from the partner protein DsbB and showed by thermal shift and isothermal titration calorimetry that it binds to PmDsbA. The crystal structures of PmDsbA, and the active site variant PmDsbAC30S were determined to high resolution. Analysis of these structures allows categorization of PmDsbA into the DsbA class exemplified by the archetypal Escherichia coli DsbA enzyme. We also present a crystal structure of PmDsbAC30S in complex with the peptide PWATCDS. The structure shows that the peptide binds non-covalently to the active site CXXC motif, the cis-Pro loop, and the hydrophobic groove adjacent to the active site of the enzyme. This high-resolution structural data provides a critical advance for future structure-based design of non-covalent peptidomimetic inhibitors. Such inhibitors would represent an entirely new antibacterial class that work by switching off the DSB virulence assembly machinery. PMID:24831013

  2. A FRET-based probe for epidermal growth factor receptor bound non-covalently to a pair of synthetic amphipathic helixes

    International Nuclear Information System (INIS)

    Itoh, Reina E.; Kurokawa, Kazuo; Fujioka, Aki; Sharma, Alok; Mayer, Bruce J.; Matsuda, Michiyuki

    2005-01-01

    Epidermal growth factor (EGF) receptor plays a pivotal role in a variety of cellular functions, such as proliferation, differentiation, and migration. To monitor the EGF receptor (EGFR) activity in living cells, we developed a probe for EGFR activity based on the principle of fluorescence resonance energy transfer (FRET). Previously, we developed a probe designated as Picchu (Phosphorylation indicator of the CrkII chimeric unit), which detects the tyrosine phosphorylation of the CrkII adaptor protein. We used a pair of synthetic amphipathic helixes, WinZipA2 and WinZipB1, to bind Picchu non-covalently to the carboxyl-terminus of the EGFR. Using this modified probe named Picchu-Z, the activity of EGFR was followed in EGF-stimulated Cos7 cells. We found that a high level of tyrosine phosphorylation of Picchu-Z probe remained after endocytosis until the point when the EGFR was translocated to the perinuclear region. These findings are in agreement with the previously reported 'signaling endosome' model. Furthermore, by pulse stimulation with EGF and by acute ablation of EGFR activity with AG1478, it was suggested that the phosphorylation of Picchu-Z probe, and probably the phosphorylation of EGFR also, underwent a rapid equilibrium (τ 1/2 < 2 min) between the phosphorylated and dephosphorylated states in the presence of EGF

  3. Noncovalent Molecular Electronics.

    Science.gov (United States)

    Gryn'ova, G; Corminboeuf, C

    2018-05-03

    Molecular electronics covers several distinctly different conducting architectures, including organic semiconductors and single-molecule junctions. The noncovalent interactions, abundant in the former, are also often found in the latter, i.e., the dimer junctions. In the present work, we draw the parallel between the two types of noncovalent molecular electronics for a range of π-conjugated heteroaromatic molecules. In silico modeling allows us to distill the factors that arise from the chemical nature of their building blocks and from their mutual arrangement. We find that the same compounds are consistently the worst and the best performers in the two types of electronic assemblies, emphasizing the universal imprint of the underlying chemistry of the molecular cores on their diverse charge transport characteristics. The interplay between molecular and intermolecular factors creates a spectrum of noncovalent conductive architectures, which can be manipulated using the design strategies based upon the established relationships between chemistry and transport.

  4. Noncovalent synthesis of protein dendrimers

    NARCIS (Netherlands)

    Lempens, E.H.M.; Baal, van I.; Dongen, van J.L.J.; Hackeng, T.M.; Merkx, M.; Meijer, E.W.

    2009-01-01

    The covalent synthesis of complex biomolecular systems such as multivalent protein dendrimers often proceeds with low efficiency, thereby making alternative strategies based on noncovalent chemistry of high interest. Here, the synthesis of protein dendrimers using a strong but noncovalent

  5. Noncovalent Hydrogen Isotope Effects

    Science.gov (United States)

    Buchachenko, A. L.; Breslavskaya, N. N.

    2018-02-01

    Zero-point energies (ZPE) and isotope effects, induced by intermolecular, noncovalent vibrations, are computed and tested by experimental data. The ZPE differences of H- and D-complexes of water with hydrogen, methane, and water molecules are about 100-300 cal/mol; they result to isotope effects IE of 1.20-1.70. Semi-ionic bonds between metal ions and water ligands in M(H2O) 6 2+ complexes are much stronger; their ZPEs are about 12-14 kcal/mol per molecule and result to IE of 1.9-2.1 at 300 K. Protonated (deuterated) water and biwater exhibit the largest ZPE differences and isotope effects; the latter are 25-28 and 12-13 for water and biwater, respectively. Noncovalent IEs contribute markedly into the experimentally measured effects and explain many anomalous and even magic properties of the effects, such as the dependence of IE on the solvents and on the presence of the third substances, enormously large isotope effects at the mild conditions, the difference between IEs measured in the reactions of individual protiated and deuterated compounds and those measured in their mixture. Noncovalent IEs are not negligible and should be taken into account to make correct and substantiated conclusions on the reaction mechanisms. The kinetic equations are derived for the total isotope effects, which include noncovalent IEs as additive factors.

  6. Noncovalent interactions in biochemistry

    Czech Academy of Sciences Publication Activity Database

    Riley, Kevin Eugene; Hobza, Pavel

    2011-01-01

    Roč. 1, č. 1 (2011), s. 3-17 ISSN 1759-0876 R&D Projects: GA MŠk LC512 Grant - others:NSF EPSCORE(US) EPS-0701525; Korea Science and Engineering Foundation(KR) R32-2008-000-10180-0 Institutional research plan: CEZ:AV0Z40550506 Keywords : noncovalent interactions * WFT calculations * DFT calculations * applications Subject RIV: CF - Physical ; Theoretical Chemistry

  7. Structure of a SUMO-binding-motif mimic bound to Smt3p–Ubc9p: conservation of a noncovalent Ubiquitin-like protein–E2 complex as a platform for selective interactions within a SUMO pathway

    Science.gov (United States)

    Duda, David M.; van Waardenburg, Robert C. A. M.; Borg, Laura A.; McGarity, Sierra; Nourse, Amanda; Waddell, M. Brett; Bjornsti, Mary-Ann; Schulman, Brenda A.

    2007-01-01

    Summary The SUMO ubiquitin-like proteins play regulatory roles in cell division, transcription, DNA repair, and protein subcellular localization. Paralleling other ubiquitin-like proteins, SUMO proteins are proteolytically processed to maturity, conjugated to targets by E1-E2-E3 cascades, and subsequently recognized by specific downstream effectors containing a SUMO-binding motif (SBM). SUMO and its E2 from the budding yeast S. cerevisiae, Smt3p and Ubc9p, are encoded by essential genes. Here we describe the 1.9 Å resolution crystal structure of a noncovalent Smt3p–Ubc9p complex. Unexpectedly, a heterologous portion of the crystallized complex derived from the expression construct mimics an SBM, and binds Smt3p in a manner resembling SBM binding to human SUMO family members. In the complex, Smt3p binds a surface distal from Ubc9's catalytic cysteine. The structure implies that a single molecule of Smt3p cannot bind concurrently to both the noncovalent binding site and the catalytic cysteine of a single Ubc9p molecule. However, formation of higher-order complexes can occur, where a single Smt3p covalently linked to one Ubc9p's catalytic cysteine also binds noncovalently to another molecule of Ubc9p. Comparison with other structures from the SUMO pathway suggests that formation of the noncovalent Smt3p–Ubc9p complex occurs mutually exclusively with many other Smt3p and Ubc9p interactions in the conjugation cascade. By contrast, high-resolution insights into how Smt3p–Ubc9p can also interact with downstream recognition machineries come from contacts with the SBM mimic. Interestingly, the overall architecture of the Smt3p–Ubc9p complex is strikingly similar to recent structures from the ubiquitin pathway. The results imply that noncovalent ubiquitin-like protein–E2 complexes are conserved platforms, which function as parts of larger assemblies involved many protein post-translational regulatory pathways. PMID:17475278

  8. Di- or polysulphide-bound biomarkers in sulphur-rich geomacromolecules as revealed by selective chemolysis

    Science.gov (United States)

    Kohnen, Math E. l.; Sinninghe Damsté, Jaap S.; Kock-van Dalen, A. c.; Jan, W. De Leeuw

    1991-05-01

    Three types of sulphur-rich high-molecular-weight material in the alkylsulphide, the polar, and the asphaltene fractions isolated from the bitumen of an immature bituminous shale from the Vena del Gesso basin (Italy) were desulphurised using Raney Ni and were treated with MeLi/MeI, a chemical degradation method which cleaves selectively and quantitatively di- or polysulphide linkages. The products formed were characterised by gas chromatography-mass spectrometry. Raney Ni desulphurisation revealed that these S-rich macromolecules are in substantial part composed of sulphur-linked biomarkers with linear, branched, isoprenoid, steroid, hopanoid, and carotenoid carbon skeletons. MeLi/Mel treatment provided evidence that a major part of the total amount of macromolecularly bound biomarkers are linked via di- or polysulphide moieties to the macromolecular network. Since the di- or polysulphide linkages are attached at specific positions of the bound biomarkers it is proposed that they are formed by intermolecular incorporation reactions of HS x- into low-molecular-weight functionalised biological lipids during early diagenesis. The different properties (solubility and molecular weight) of the sulphur-rich macromolecules in the alkylsulphide, the resin, and the asphaltene fractions can be explained simply by differences in degree of sulphur cross-linking.

  9. Transparency Trade-offs for a 3-channel Controller Revealed by the Bounded Environment Passivity Method

    OpenAIRE

    Willaert, Bert; Corteville, Brecht; Reynaerts, Dominiek; Van Brussel, Hendrik; Vander Poorten, Emmanuel

    2010-01-01

    In this paper, the Bounded Environment Passivity method [1] is applied to a 3-channel controller. This method enables the design of teleoperation controllers that show passive behaviour for interactions with a bounded range of environments. The resulting tuning guidelines, derived analytically, provide interesting tuning flexibility, which allows to focus on different aspects of transparency. As telesurgery is the motivation behind this work, the focus lies on correctly r...

  10. The origins of the directionality of noncovalent intermolecular interactions.

    Science.gov (United States)

    Wang, Changwei; Guan, Liangyu; Danovich, David; Shaik, Sason; Mo, Yirong

    2016-01-05

    The recent σ-hole concept emphasizes the contribution of electrostatic attraction to noncovalent bonds, and implies that the electrostatic force has an angular dependency. Here a set of clusters, which includes hydrogen bonding, halogen bonding, chalcogen bonding, and pnicogen bonding systems, is investigated to probe the magnitude of covalency and its contribution to the directionality in noncovalent bonding. The study is based on the block-localized wavefunction (BLW) method that decomposes the binding energy into the steric and the charge transfer (CT) (hyperconjugation) contributions. One unique feature of the BLW method is its capability to derive optimal geometries with only steric effect taken into account, while excluding the CT interaction. The results reveal that the overall steric energy exhibits angular dependency notably in halogen bonding, chalcogen bonding, and pnicogen bonding systems. Turning on the CT interactions further shortens the intermolecular distances. This bond shortening enhances the Pauli repulsion, which in turn offsets the electrostatic attraction, such that in the final sum, the contribution of the steric effect to bonding is diminished, leaving the CT to dominate the binding energy. In several other systems particularly hydrogen bonding systems, the steric effect nevertheless still plays the major role whereas the CT interaction is minor. However, in all cases, the CT exhibits strong directionality, suggesting that the linearity or near linearity of noncovalent bonds is largely governed by the charge-transfer interaction whose magnitude determines the covalency in noncovalent bonds. © 2015 Wiley Periodicals, Inc.

  11. Two-dimensional sum-frequency generation (2D SFG) reveals structure and dynamics of a surface-bound peptide

    Science.gov (United States)

    Laaser, Jennifer E.; Skoff, David R.; Ho, Jia-Jung; Joo, Yongho; Serrano, Arnaldo L.; Steinkruger, Jay D.; Gopalan, Padma; Gellman, Samuel H.; Zanni, Martin T.

    2014-01-01

    Surface-bound polypeptides and proteins are increasingly used to functionalize inorganic interfaces such as electrodes, but their structural characterization is exceedingly difficult with standard technologies. In this paper, we report the first two-dimensional sum-frequency generation (2D SFG) spectra of a peptide monolayer, which is collected by adding a mid-IR pulse shaper to a standard femtosecond SFG spectrometer. On a gold surface, standard FTIR spectroscopy is inconclusive about the peptide structure because of solvation-induced frequency shifts, but the 2D lineshapes, anharmonic shifts, and lifetimes obtained from 2D SFG reveal that the peptide is largely α-helical and upright. Random coil residues are also observed, which do not themselves appear in SFG spectra due to their isotropic structural distribution, but which still absorb infrared light and so can be detected by cross-peaks in 2D SFG spectra. We discuss these results in the context of peptide design. Because of the similar way in which the spectra are collected, these 2D SFG spectra can be directly compared to 2D IR spectra, thereby enabling structural interpretations of surface-bound peptides and biomolecules based on the well-studied structure/2D IR spectra relationships established from soluble proteins. PMID:24372101

  12. Noncovalent binding of 4-nitroquinoline-N-oxide to proteins

    International Nuclear Information System (INIS)

    Yamamoto, Osamu

    1979-01-01

    Binding of 4NQO to various kinds of enzymes or proteins was studied. Each one of proteins was mixed with 4NQO in 0.4 mM NaHCO 3 solution and eluted through Ultrogel AcA 22 column. Radioactivity of 14 C-labeled 4NQO found in protein fraction was measured. 4NQO bound hardly to polyglutamic acid and polyaspertic acid, somewhat to serum albumin, insulin, trypsin, RNA polymerase and DNA polymerase, and markedly to ureas which is an SH enzyme. Lactate dehydrogenase, one of SH enzymes, aggregated with 4NQO. The binding of SH enzyme with the N-oxide would be attributable to a noncovalent binding such as >N-O---H-S-, because 4NQO-urease binding yield markedly decreased in the presence of sodium dodecyl sulfate or cysteine, and also 4NQO-bound urease released 4NQO by the addition of sodium dodecyl sulfate. (author)

  13. Noncovalent binding of 4-nitroquinoline-N-oxide to proteins

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, O [Hiroshima Univ. (Japan). Research Inst. for Nuclear Medicine and Biology

    1979-12-01

    Binding of 4NQO to various kinds of enzymes or proteins was studied. Each one of proteins was mixed with 4NQO in 0.4 mM NaHCO/sub 3/ solution and eluted through Ultrogel AcA 22 column. Radioactivity of /sup 14/C-labeled 4NQO found in protein fraction was measured. 4NQO bound hardly to polyglutamic acid and polyaspertic acid, somewhat to serum albumin, insulin, trypsin, RNA polymerase and DNA polymerase, and markedly to ureas which is an SH enzyme. Lactate dehydrogenase, one of SH enzymes, aggregated with 4NQO. The binding of SH enzyme with the N-oxide would be attributable to a noncovalent binding such as >N-O---H-S-, because 4NQO-urease binding yield markedly decreased in the presence of sodium dodecyl sulfate or cysteine, and also 4NQO-bound urease released 4NQO by the addition of sodium dodecyl sulfate.

  14. Noncovalent Interactions in Organic Electronic Materials

    KAUST Repository

    Ravva, Mahesh Kumar; Risko, Chad; Bredas, Jean-Luc

    2017-01-01

    In this chapter, we provide an overview of how noncovalent interactions, determined by the chemical structure of π-conjugated molecules and polymers, govern essential aspects of the electronic, optical, and mechanical characteristics of organic

  15. Dynamic features of apo and bound HIV-Nef protein reveal the anti-HIV dimerization inhibition mechanism.

    Science.gov (United States)

    Moonsamy, Suri; Bhakat, Soumendranath; Soliman, Mahmoud E S

    2015-01-01

    The first account on the dynamic features of Nef or negative factor, a small myristoylated protein located in the cytoplasm believes to increase HIV-1 viral titer level, is reported herein. Due to its major role in HIV-1 pathogenicity, Nef protein is considered an emerging target in anti-HIV drug design and discovery process. In this study, comparative long-range all-atom molecular dynamics simulations were employed for apo and bound protein to unveil molecular mechanism of HIV-Nef dimerization and inhibition. Results clearly revealed that B9, a newly discovered Nef inhibitor, binds at the dimeric interface of Nef protein and caused significant separation between orthogonally opposed residues, namely Asp108, Leu112 and Gln104. Large differences in magnitudes were observed in the radius of gyration (∼1.5 Å), per-residue fluctuation (∼2 Å), C-alpha deviations (∼2 Å) which confirm a comparatively more flexible nature of apo conformation due to rapid dimeric association. Compared to the bound conformer, a more globally correlated motion in case of apo structure of HIV-Nef confirms the process of dimeric association. This clearly highlights the process of inhibition as a result of ligand binding. The difference in principal component analysis (PCA) scatter plot and per-residue mobility plot across first two normal modes further justifies the same findings. The in-depth dynamic analyses of Nef protein presented in this report would serve crucial in understanding its function and inhibition mechanisms. Information on inhibitor binding mode would also assist in designing of potential inhibitors against this important HIV target.

  16. Crystal structure of APOBEC3A bound to single-stranded DNA reveals structural basis for cytidine deamination and specificity.

    Science.gov (United States)

    Kouno, Takahide; Silvas, Tania V; Hilbert, Brendan J; Shandilya, Shivender M D; Bohn, Markus F; Kelch, Brian A; Royer, William E; Somasundaran, Mohan; Kurt Yilmaz, Nese; Matsuo, Hiroshi; Schiffer, Celia A

    2017-04-28

    Nucleic acid editing enzymes are essential components of the immune system that lethally mutate viral pathogens and somatically mutate immunoglobulins, and contribute to the diversification and lethality of cancers. Among these enzymes are the seven human APOBEC3 deoxycytidine deaminases, each with unique target sequence specificity and subcellular localization. While the enzymology and biological consequences have been extensively studied, the mechanism by which APOBEC3s recognize and edit DNA remains elusive. Here we present the crystal structure of a complex of a cytidine deaminase with ssDNA bound in the active site at 2.2 Å. This structure not only visualizes the active site poised for catalysis of APOBEC3A, but pinpoints the residues that confer specificity towards CC/TC motifs. The APOBEC3A-ssDNA complex defines the 5'-3' directionality and subtle conformational changes that clench the ssDNA within the binding groove, revealing the architecture and mechanism of ssDNA recognition that is likely conserved among all polynucleotide deaminases, thereby opening the door for the design of mechanistic-based therapeutics.

  17. Noncovalent Interactions in Organic Electronic Materials

    KAUST Repository

    Ravva, Mahesh Kumar

    2017-06-29

    In this chapter, we provide an overview of how noncovalent interactions, determined by the chemical structure of π-conjugated molecules and polymers, govern essential aspects of the electronic, optical, and mechanical characteristics of organic semiconductors. We begin by describing general aspects of materials design, including the wide variety of chemistries exploited to control the electronic and optical properties of these materials. We then discuss explicit examples of how the study of noncovalent interactions can provide deeper chemical insights that can improve the design of new generations of organic electronic materials.

  18. The noncovalent bonding of antibiotics to a polytetrafluoroethylene-benzalkonium graft

    International Nuclear Information System (INIS)

    Harvey, R.A.; Greco, R.S.

    1981-01-01

    This study evaluates the noncovalent bonding of anionic antibiotics to polytetrafluoroethylene grafts using benzalkonium chloride as a cationic anchor. The binding of radiolabeled surfactants and antibiotics was evaluated by liquid scintillation and in an in vitro microbiologic assay against Staphylococcus aureus. Significant quantities of antibiotic were bound when the grafts were pretreated with benzalkonium in ethanol or aqueous solution at elevated temperature. Bound antibiotic is stable in aqueous salt solutions, but slowly dissociates in the presence of blood or serum. The ionic nature of the bonding process is clarified by the use of a variety of antibiotics and surfactants with complementary charges. The ability of the benzalkonium treated grafts to adsorb antibiotic from blood is, likewise, demonstrated and the possibility of concomitantly binding heparin and antibiotic simultaneously is evaluated. These studies support the ability to noncovalently bond antibiotics to polytetrafluoroethylene surfaces and form the basis of eventually utilizing these surfaces in the prevention of vascular prosthetic infections

  19. Native Liquid Extraction Surface Analysis Mass Spectrometry: Analysis of Noncovalent Protein Complexes Directly from Dried Substrates

    Science.gov (United States)

    Martin, Nicholas J.; Griffiths, Rian L.; Edwards, Rebecca L.; Cooper, Helen J.

    2015-08-01

    Liquid extraction surface analysis (LESA) mass spectrometry is a promising tool for the analysis of intact proteins from biological substrates. Here, we demonstrate native LESA mass spectrometry of noncovalent protein complexes of myoglobin and hemoglobin from a range of surfaces. Holomyoglobin, in which apomyoglobin is noncovalently bound to the prosthetic heme group, was observed following LESA mass spectrometry of myoglobin dried onto glass and polyvinylidene fluoride surfaces. Tetrameric hemoglobin [(αβ)2 4H] was observed following LESA mass spectrometry of hemoglobin dried onto glass and polyvinylidene fluoride (PVDF) surfaces, and from dried blood spots (DBS) on filter paper. Heme-bound dimers and monomers were also observed. The `contact' LESA approach was particularly suitable for the analysis of hemoglobin tetramers from DBS.

  20. Crystal Structures of Staphylococcus epidermidis Mevalonate Diphosphate Decarboxylase Bound to Inhibitory Analogs Reveal New Insight into Substrate Binding and Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Barta, Michael L.; Skaff, D. Andrew; McWhorter, William J.; Herdendorf, Timothy J.; Miziorko, Henry M.; Geisbrecht, Brian V. (UMKC)

    2011-10-28

    The polyisoprenoid compound undecaprenyl phosphate is required for biosynthesis of cell wall peptidoglycans in Gram-positive bacteria, including pathogenic Enterococcus, Streptococcus, and Staphylococcus spp. In these organisms, the mevalonate pathway is used to produce the precursor isoprenoid, isopentenyl 5-diphosphate. Mevalonate diphosphate decarboxylase (MDD) catalyzes formation of isopentenyl 5-diphosphate in an ATP-dependent irreversible reaction and is therefore an attractive target for inhibitor development that could lead to new antimicrobial agents. To facilitate exploration of this possibility, we report the crystal structure of Staphylococcus epidermidis MDD (1.85 {angstrom} resolution) and, to the best of our knowledge, the first structures of liganded MDD. These structures include MDD bound to the mevalonate 5-diphosphate analogs diphosphoglycolyl proline (2.05 {angstrom} resolution) and 6-fluoromevalonate diphosphate (FMVAPP; 2.2 {angstrom} resolution). Comparison of these structures provides a physical basis for the significant differences in K{sub i} values observed for these inhibitors. Inspection of enzyme/inhibitor structures identified the side chain of invariant Ser{sup 192} as making potential contributions to catalysis. Significantly, Ser {yields} Ala substitution of this side chain decreases k{sub cat} by {approx}10{sup 3}-fold, even though binding interactions between FMVAPP and this mutant are similar to those observed with wild type MDD, as judged by the 2.1 {angstrom} cocrystal structure of S192A with FMVAPP. Comparison of microbial MDD structures with those of mammalian counterparts reveals potential targets at the active site periphery that may be exploited to selectively target the microbial enzymes. These studies provide a structural basis for previous observations regarding the MDD mechanism and inform future work toward rational inhibitor design.

  1. Coherence-enhanced phase-dependent dissipation in long SNS Josephson junctions: Revealing Andreev bound state dynamics

    Science.gov (United States)

    Dassonneville, B.; Murani, A.; Ferrier, M.; Guéron, S.; Bouchiat, H.

    2018-05-01

    the quantum dynamics of Andreev bound states. By spanning different physical regimes, our experiments provide unique access to inelastic scattering and spectroscopy of an isolated quantum coherent system, and reveal the associated relaxation times. This technique should be a tool of choice to investigate topological superconductivity and detect the topological protection of edge states.

  2. Aryloxyalkanoic Acids as Non-Covalent Modifiers of the Allosteric Properties of Hemoglobin

    Directory of Open Access Journals (Sweden)

    Abdelsattar M. Omar

    2016-08-01

    Full Text Available Hemoglobin (Hb modifiers that stereospecifically inhibit sickle hemoglobin polymer formation and/or allosterically increase Hb affinity for oxygen have been shown to prevent the primary pathophysiology of sickle cell disease (SCD, specifically, Hb polymerization and red blood cell sickling. Several such compounds are currently being clinically studied for the treatment of SCD. Based on the previously reported non-covalent Hb binding characteristics of substituted aryloxyalkanoic acids that exhibited antisickling properties, we designed, synthesized and evaluated 18 new compounds (KAUS II series for enhanced antisickling activities. Surprisingly, select test compounds showed no antisickling effects or promoted erythrocyte sickling. Additionally, the compounds showed no significant effect on Hb oxygen affinity (or in some cases, even decreased the affinity for oxygen. The X-ray structure of deoxygenated Hb in complex with a prototype compound, KAUS-23, revealed that the effector bound in the central water cavity of the protein, providing atomic level explanations for the observed functional and biological activities. Although the structural modification did not lead to the anticipated biological effects, the findings provide important direction for designing candidate antisickling agents, as well as a framework for novel Hb allosteric effectors that conversely, decrease the protein affinity for oxygen for potential therapeutic use for hypoxic- and/or ischemic-related diseases.

  3. Andreev Bound States Formation and Quasiparticle Trapping in Quench Dynamics Revealed by Time-Dependent Counting Statistics.

    Science.gov (United States)

    Souto, R Seoane; Martín-Rodero, A; Yeyati, A Levy

    2016-12-23

    We analyze the quantum quench dynamics in the formation of a phase-biased superconducting nanojunction. We find that in the absence of an external relaxation mechanism and for very general conditions the system gets trapped in a metastable state, corresponding to a nonequilibrium population of the Andreev bound states. The use of the time-dependent full counting statistics analysis allows us to extract information on the asymptotic population of even and odd many-body states, demonstrating that a universal behavior, dependent only on the Andreev state energy, is reached in the quantum point contact limit. These results shed light on recent experimental observations on quasiparticle trapping in superconducting atomic contacts.

  4. Targeting membrane-bound viral RNA synthesis reveals potent inhibition of diverse coronaviruses including the middle East respiratory syndrome virus.

    Directory of Open Access Journals (Sweden)

    Anna Lundin

    2014-05-01

    Full Text Available Coronaviruses raise serious concerns as emerging zoonotic viruses without specific antiviral drugs available. Here we screened a collection of 16671 diverse compounds for anti-human coronavirus 229E activity and identified an inhibitor, designated K22, that specifically targets membrane-bound coronaviral RNA synthesis. K22 exerts most potent antiviral activity after virus entry during an early step of the viral life cycle. Specifically, the formation of double membrane vesicles (DMVs, a hallmark of coronavirus replication, was greatly impaired upon K22 treatment accompanied by near-complete inhibition of viral RNA synthesis. K22-resistant viruses contained substitutions in non-structural protein 6 (nsp6, a membrane-spanning integral component of the viral replication complex implicated in DMV formation, corroborating that K22 targets membrane bound viral RNA synthesis. Besides K22 resistance, the nsp6 mutants induced a reduced number of DMVs, displayed decreased specific infectivity, while RNA synthesis was not affected. Importantly, K22 inhibits a broad range of coronaviruses, including Middle East respiratory syndrome coronavirus (MERS-CoV, and efficient inhibition was achieved in primary human epithelia cultures representing the entry port of human coronavirus infection. Collectively, this study proposes an evolutionary conserved step in the life cycle of positive-stranded RNA viruses, the recruitment of cellular membranes for viral replication, as vulnerable and, most importantly, druggable target for antiviral intervention. We expect this mode of action to serve as a paradigm for the development of potent antiviral drugs to combat many animal and human virus infections.

  5. Crystal structure of the adenosine A 2A receptor bound to an antagonist reveals a potential allosteric pocket

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Bingfa; Bachhawat, Priti; Chu, Matthew Ling-Hon; Wood, Martyn; Ceska, Tom; Sands, Zara A.; Mercier, Joel; Lebon, Florence; Kobilka, Tong Sun; Kobilka, Brian K. (Stanford-MED); (ConfometRx); (UCB Pharma)

    2017-02-06

    The adenosine A2A receptor (A2AR) has long been implicated in cardiovascular disorders. As more selective A2AR ligands are being identified, its roles in other disorders, such as Parkinson’s disease, are starting to emerge, and A2AR antagonists are important drug candidates for nondopaminergic anti-Parkinson treatment. Here we report the crystal structure of A2A receptor bound to compound 1 (Cmpd-1), a novel A2AR/N-methyl D-aspartate receptor subtype 2B (NR2B) dual antagonist and potential anti-Parkinson candidate compound, at 3.5 Å resolution. The A2A receptor with a cytochrome b562-RIL (BRIL) fusion (A2AR–BRIL) in the intracellular loop 3 (ICL3) was crystallized in detergent micelles using vapor-phase diffusion. Whereas A2AR–BRIL bound to the antagonist ZM241385 has previously been crystallized in lipidic cubic phase (LCP), structural differences in the Cmpd-1–bound A2AR–BRIL prevented formation of the lattice observed with the ZM241385–bound receptor. The crystals grew with a type II crystal lattice in contrast to the typical type I packing seen from membrane protein structures crystallized in LCP. Cmpd-1 binds in a position that overlaps with the native ligand adenosine, but its methoxyphenyl group extends to an exosite not previously observed in other A2AR structures. Structural analysis revealed that Cmpd-1 binding results in the unique conformations of two tyrosine residues, Tyr91.35 and Tyr2717.36, which are critical for the formation of the exosite. The structure reveals insights into antagonist binding that are not observed in other A2AR structures, highlighting flexibility in the binding pocket that may facilitate the development of A2AR-selective compounds for the treatment of Parkinson’s disease.

  6. Different functions of the insect soluble and membrane-bound trehalase genes in chitin biosynthesis revealed by RNA interference.

    Directory of Open Access Journals (Sweden)

    Jie Chen

    Full Text Available BACKGROUND: Trehalase, an enzyme that hydrolyzes trehalose to yield two glucose molecules, plays a pivotal role in various physiological processes. In recent years, trehalase proteins have been purified from several insect species and are divided into soluble (Tre-1 and membrane-bound (Tre-2 trehalases. However, no functions of the two trehalases in chitin biosynthesis in insects have yet been reported. PRINCIPAL FINDINGS: The membrane-bound trehalase of Spodoptera exigua (SeTre-2 was characterized in our laboratory previously. In this study, we cloned the soluble trehalase gene (SeTre-1 and investigated the tissue distribution and developmental expression pattern of the two trehalase genes. SeTre-1 was expressed highly in cuticle and Malpighian tubules, while SeTre-2 was expressed in tracheae and fat body. In the midgut, the two trehalase genes were expressed in different locations. Additionally, the expression profiles of both trehalase mRNAs and their enzyme activities suggest that they may play different roles in chitin biosynthesis. The RNA interference (RNAi of either SeTre-1 or SeTre-2 was gene-specific and effective, with efficiency rates up to 83% at 72 h post injection. After RNAi of SeTre-1 and SeTre-2, significant higher mortality rates were observed during the larva-pupa stage and pupa-adult stage, and the lethal phenotypes were classified and analyzed. Additionally, the change trends of concentration of trehalose and glucose appeared reciprocally in RNAi-mutants. Moreover, knockdown of SeTre-1 gene largely inhibited the expression of chitin synthase gene A (CHSA and reduced the chitin content in the cuticle to two-thirds relative to the control insects. The chitin synthase gene B (CHSB expression, however, was inhibited more by the injection of dsRNA for SeTre-2, and the chitin content in the midgut decreased by about 25%. CONCLUSIONS: SeTre-1 plays a major role in CHSA expression and chitin synthesis in the cuticle, and SeTre-2

  7. Characterising non-covalent interactions with the Cambridge Structural Database.

    Science.gov (United States)

    Lommerse, J P; Taylor, R

    1997-02-01

    This review describes how the CSD can be used to study non-covalent interactions. Several different types of information may be obtained. First, the relative frequencies of various interactions can be studied; for example, we have shown that the terminal oxygen atoms of phosphate groups accept hydrogen bonds far more often than the linkage oxygens. Secondly, information can be obtained about the geometries of nonbonded contacts; for example, hydrogen bonds to P-O groups rarely form along the extension of the P-O bond, whereas short contacts between oxygen and carbon-bound iodine show a strong preference for linear C-I ... O angles. Thirdly, the CSD can be searched for novel interactions which may be exploited in inhibitor design; for example, the I ... O contacts just mentioned, and N-H ... pi hydrogen bonds. Finally, the CSD can suggest synthetic targets for medicinal chemistry; for example, molecules containing delocalised electron deficient groups such as trimethylammonium, pyridinium, thaizolium and dinitrophenyl have a good chance of binding to an active-site tryptophan. Although the CSD contains small-molecule crystal structures, not protein-ligand complexes, there is considerable evidence that the contacts seen in the two types of structures are similar. We have illustrated this a number of times in the present review and additional evidence has been given previously by Klebe. The major advantages of the CSD are its size, diversity and experimental accuracy. For these reasons, it is a useful tool for modellers engaged in rational inhibitor design.

  8. Synthesis and characterization of new chiral ketopinic acid-derived catalysts immobilized on polystyrene-bound imidazole

    Directory of Open Access Journals (Sweden)

    Hassan Yusuf

    2017-02-01

    Full Text Available Four new chiral ketopinic acid-derived catalysts were anchored on a polystyrene-bound imidazole via non-covalent bond. The resulting heterogeneous catalysts were successfully characterized using IR, SEM, and TGA analyses.

  9. Non-covalent associative structure of coal

    Energy Technology Data Exchange (ETDEWEB)

    Shui, H. [Anhui University of Technology, Maanshan (China). School of Chemistry and Chemical Engineering

    2004-06-01

    The recent progress of non-covalent associative structure of coal and the mechanisms of the carbon disulphide-N-methyl-2-pyrrolidone (CS{sub 2}/NMP) are mixed solvent and the additive addition enhancing the extraction yield of coals are reviewed, and the aggregation behaviour of coal in solid and solution states are presented, and the aggregation behavior of coal in solid and solution states are introduced in this paper. Coal extraction and swelling in organic solvents at room temperature were the most useful methods to understand the associative structure of coal. CS{sub 2}/NMP is a unique solvent to give high extraction yields for some bituminous coals. Some additives such as tetracyanoethylene (TCNE) can dissociate the stronger interactions among coal molecules and enhance the extraction yields of coal in the mixed solvent. 37 refs., 1 fig.

  10. Predominantly ligand guided non-covalently linked assemblies of ...

    Indian Academy of Sciences (India)

    JUBARAJ B BARUAH

    2018-05-12

    May 12, 2018 ... Abstract. Various non-covalently linked inorganic self-assemblies formed by the supramolecular interacting .... metal-organic frameworks.59 Inorganic chemists rou- ...... two-dimensional organic–inorganic layered perovskite.

  11. A thiamin-bound, pre-decarboxylation reaction intermediate analogue in the pyruvate dehydrogenase E1 subunit induces large scale disorder-to-order transformations in the enzyme and reveals novel structural features in the covalently bound adduct.

    Science.gov (United States)

    Arjunan, Palaniappa; Sax, Martin; Brunskill, Andrew; Chandrasekhar, Krishnamoorthy; Nemeria, Natalia; Zhang, Sheng; Jordan, Frank; Furey, William

    2006-06-02

    The crystal structure of the E1 component from the Escherichia coli pyruvate dehydrogenase multienzyme complex (PDHc) has been determined with phosphonolactylthiamin diphosphate (PLThDP) in its active site. PLThDP serves as a structural and electrostatic analogue of the natural intermediate alpha-lactylthiamin diphosphate (LThDP), in which the carboxylate from the natural substrate pyruvate is replaced by a phosphonate group. This represents the first example of an experimentally determined, three-dimensional structure of a thiamin diphosphate (ThDP)-dependent enzyme containing a covalently bound, pre-decarboxylation reaction intermediate analogue and should serve as a model for the corresponding intermediates in other ThDP-dependent decarboxylases. Regarding the PDHc-specific reaction, the presence of PLThDP induces large scale conformational changes in the enzyme. In conjunction with the E1-PLThDP and E1-ThDP structures, analysis of a H407A E1-PLThDP variant structure shows that an interaction between His-407 and PLThDP is essential for stabilization of two loop regions in the active site that are otherwise disordered in the absence of intermediate analogue. This ordering completes formation of the active site and creates a new ordered surface likely involved in interactions with the lipoyl domains of E2s within the PDHc complex. The tetrahedral intermediate analogue is tightly held in the active site through direct hydrogen bonds to residues His-407, Tyr-599, and His-640 and reveals a new, enzyme-induced, strain-related feature that appears to aid in the decarboxylation process. This feature is almost certainly present in all ThDP-dependent decarboxylases; thus its inclusion in our understanding of general thiamin catalysis is important.

  12. Krypton Derivatization of an O2 -Tolerant Membrane-Bound [NiFe] Hydrogenase Reveals a Hydrophobic Tunnel Network for Gas Transport.

    Science.gov (United States)

    Kalms, Jacqueline; Schmidt, Andrea; Frielingsdorf, Stefan; van der Linden, Peter; von Stetten, David; Lenz, Oliver; Carpentier, Philippe; Scheerer, Patrick

    2016-04-25

    [NiFe] hydrogenases are metalloenzymes catalyzing the reversible heterolytic cleavage of hydrogen into protons and electrons. Gas tunnels make the deeply buried active site accessible to substrates and inhibitors. Understanding the architecture and function of the tunnels is pivotal to modulating the feature of O2 tolerance in a subgroup of these [NiFe] hydrogenases, as they are interesting for developments in renewable energy technologies. Here we describe the crystal structure of the O2 -tolerant membrane-bound [NiFe] hydrogenase of Ralstonia eutropha (ReMBH), using krypton-pressurized crystals. The positions of the krypton atoms allow a comprehensive description of the tunnel network within the enzyme. A detailed overview of tunnel sizes, lengths, and routes is presented from tunnel calculations. A comparison of the ReMBH tunnel characteristics with crystal structures of other O2 -tolerant and O2 -sensitive [NiFe] hydrogenases revealed considerable differences in tunnel size and quantity between the two groups, which might be related to the striking feature of O2 tolerance. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Direct effects of ionizing radiation on integral membrane proteins. Noncovalent energy transfer requires specific interpeptide interactions

    International Nuclear Information System (INIS)

    Jhun, E.; Jhun, B.H.; Jones, L.R.; Jung, C.Y.

    1991-01-01

    The 12 transmembrane alpha helices (TMHs) of human erythrocyte glucose transporter were individually cut by pepsin digestion as membrane-bound 2.5-3.5-kDa peptide fragments. Radiation-induced chemical degradation of these fragments showed an average target size of 34 kDa. This is 10-12 x larger than the average size of an individual TMH, demonstrating that a significant energy transfer occurs among these TMHs in the absence of covalent linkage. Heating this TMH preparation at 100 degree C for 15 min reduced the target size to 5 kDa or less, suggesting that the noncovalent energy transfer requires specific helix-helix interactions. Purified phospholamban, a small (6-kDa) integral membrane protein containing a single TMH, formed a pentameric assembly in sodium dodecyl sulfate. The chemical degradation target size of this phospholamban pentamer was 5-6 kDa, illustrating that not all integral membrane protein assemblies permit intersubunit energy transfer. These findings together with other published observations suggest strongly that significant noncovalent energy transfer can occur within the tertiary and quaternary structure of membrane proteins and that as yet undefined proper molecular interactions are required for such covalent energy transfer. Our results with pepsin-digested glucose transporter also illustrate the importance of the interhelical interaction as a predominating force in maintaining the tertiary structure of a transmembrane protein

  14. Noncovalent Labeling of Biomolecules with Red and Near- Infrared Dyes

    Directory of Open Access Journals (Sweden)

    Lucjan Strekowski

    2004-02-01

    Full Text Available Biopolymers such as proteins and nucleic acids can be labeled with a fluorescent marker to allow for their detection. Covalent labeling is achieved by the reaction of an appropriately functionalized dye marker with a reactive group on a biomolecule. The recent trend, however, is the use of noncovalent labeling that results from strong hydrophobic and/or ionic interactions between the marker and biomolecule of interest. The main advantage of noncovalent labeling is that it affects the functional activity of the biomolecule to a lesser extent. The applications of luminescent cyanine and squarylium dyes are reviewed.

  15. The crystal structure of the interleukin 21 receptor bound to interleukin 21 reveals that a sugar chain interacting with the WSXWS motif is an integral part of the interleukin 21 receptor

    DEFF Research Database (Denmark)

    Hamming, Ole Jensen; Kang, Lishan; Svensson, Anders

    2012-01-01

    to be a consensus sequence for C-mannosylation. Here we present the crystal structure of IL-21 bound to IL-21R and reveal that the WSXWS motif of IL-21R is C-mannosylated on the first tryptophan. We furthermore demonstrate that a sugar chain bridge the two fibronectin domains which constitute the extracellular...

  16. Benchmark Calculations of Noncovalent Interactions of Halogenated Molecules

    Czech Academy of Sciences Publication Activity Database

    Řezáč, Jan; Riley, Kevin Eugene; Hobza, Pavel

    2012-01-01

    Roč. 8, č. 11 (2012), s. 4285-4292 ISSN 1549-9618 R&D Projects: GA ČR GBP208/12/G016 Institutional support: RVO:61388963 Keywords : halogenated molecules * noncovalent interactions * benchmark calculations Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.389, year: 2012

  17. Multi-step non-covalent pathways to supramolecular systems

    NARCIS (Netherlands)

    Hermans, T.M.

    2010-01-01

    The spontaneous organization of building blocks into ordered structures governed by non-covalent interactions, or self-assembly, is a commonly encountered pathway in nature to obtain functional materials. These materials often consist of many different components ordered into intricate structures.

  18. Preventing disulfide bond formation weakens non-covalent forces among lysozyme aggregates.

    Directory of Open Access Journals (Sweden)

    Vijay Kumar Ravi

    Full Text Available Nonnative disulfide bonds have been observed among protein aggregates in several diseases like amyotrophic lateral sclerosis, cataract and so on. The molecular mechanism by which formation of such bonds promotes protein aggregation is poorly understood. Here in this work we employ previously well characterized aggregation of hen eggwhite lysozyme (HEWL at alkaline pH to dissect the molecular role of nonnative disulfide bonds on growth of HEWL aggregates. We employed time-resolved fluorescence anisotropy, atomic force microscopy and single-molecule force spectroscopy to quantify the size, morphology and non-covalent interaction forces among the aggregates, respectively. These measurements were performed under conditions when disulfide bond formation was allowed (control and alternatively when it was prevented by alkylation of free thiols using iodoacetamide. Blocking disulfide bond formation affected growth but not growth kinetics of aggregates which were ∼50% reduced in volume, flatter in vertical dimension and non-fibrillar in comparison to control. Interestingly, single-molecule force spectroscopy data revealed that preventing disulfide bond formation weakened the non-covalent interaction forces among monomers in the aggregate by at least ten fold, thereby stalling their growth and yielding smaller aggregates in comparison to control. We conclude that while constrained protein chain dynamics in correctly disulfide bonded amyloidogenic proteins may protect them from venturing into partial folded conformations that can trigger entry into aggregation pathways, aberrant disulfide bonds in non-amyloidogenic proteins (like HEWL on the other hand, may strengthen non-covalent intermolecular forces among monomers and promote their aggregation.

  19. Positive and negative ion mode comparison for the determination of DNA/peptide noncovalent binding sites through the formation of "three-body" noncovalent fragment ions.

    Science.gov (United States)

    Brahim, Bessem; Tabet, Jean-Claude; Alves, Sandra

    2018-02-01

    Gas-phase fragmentation of single strand DNA-peptide noncovalent complexes is investigated in positive and negative electrospray ionization modes.Collision-induced dissociation experiments, performed on the positively charged noncovalent complex precursor ions, have confirmed the trend previously observed in negative ion mode, i.e. a high stability of noncovalent complexes containing very basic peptidic residues (i.e. R > K) and acidic nucleotide units (i.e. Thy units), certainly incoming from the existence of salt bridge interactions. Independent of the ion polarity, stable noncovalent complex precursor ions were found to dissociate preferentially through covalent bond cleavages of the partners without disrupting noncovalent interactions. The resulting DNA fragment ions were found to be still noncovalently linked to the peptides. Additionally, the losses of an internal nucleic fragment producing "three-body" noncovalent fragment ions were also observed in both ion polarities, demonstrating the spectacular salt bridge interaction stability. The identical fragmentation patterns (regardless of the relative fragment ion abundances) observed in both polarities have shown a common location of salt bridge interaction certainly preserved from solution. Nonetheless, most abundant noncovalent fragment ions (and particularly three-body ones) are observed from positively charged noncovalent complexes. Therefore, we assume that, independent of the preexisting salt bridge interaction and zwitterion structures, multiple covalent bond cleavages from single-stranded DNA/peptide complexes rely on an excess of positive charges in both electrospray ionization ion polarities.

  20. Four levels of hierarchical organization, including noncovalent chainmail, brace the mature tumor herpesvirus capsid against pressurization.

    Science.gov (United States)

    Zhou, Z Hong; Hui, Wong Hoi; Shah, Sanket; Jih, Jonathan; O'Connor, Christine M; Sherman, Michael B; Kedes, Dean H; Schein, Stan

    2014-10-07

    Like many double-stranded DNA viruses, tumor gammaherpesviruses Epstein-Barr virus and Kaposi's sarcoma-associated herpesvirus withstand high internal pressure. Bacteriophage HK97 uses covalent chainmail for this purpose, but how this is achieved noncovalently in the much larger gammaherpesvirus capsid is unknown. Our cryoelectron microscopy structure of a gammaherpesvirus capsid reveals a hierarchy of four levels of organization: (1) Within a hexon capsomer, each monomer of the major capsid protein (MCP), 1,378 amino acids and six domains, interacts with its neighboring MCPs at four sites. (2) Neighboring capsomers are linked in pairs by MCP dimerization domains and in groups of three by heterotrimeric triplex proteins. (3) Small (∼280 amino acids) HK97-like domains in MCP monomers alternate with triplex heterotrimers to form a belt that encircles each capsomer. (4) One hundred sixty-two belts concatenate to form noncovalent chainmail. The triplex heterotrimer orchestrates all four levels and likely drives maturation to an angular capsid that can withstand pressurization. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Calculations on Noncovalent Interactions and Databases of Benchmark Interaction Energies

    Czech Academy of Sciences Publication Activity Database

    Hobza, Pavel

    2012-01-01

    Roč. 45, č. 4 (2012), s. 663-672 ISSN 0001-4842 R&D Projects: GA ČR GBP208/12/G016 Grant - others:European Social Fund(XE) CZ.1.05/2.1.00/03.0058 Institutional research plan: CEZ:AV0Z40550506 Keywords : non-covalent interactions * covalent interactions * quantum chemical approach Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 20.833, year: 2012

  2. Enzymatic Activity Enhancement of Non-Covalent Modified Superoxide Dismutase and Molecular Docking Analysis

    Directory of Open Access Journals (Sweden)

    Fa-Jun Song

    2012-03-01

    Full Text Available The enzyme activity of superoxide dismutase was improved in the pyrogallol autoxidation system by about 27%, after interaction between hydroxypropyl-β-cyclo- dextrin and superoxide dismutase. Fluorescence spectrometry was used to study the interaction between hydroxypropyl-β-cyclodextrin and superoxide dismutase at different temperatures. By doing this, it can be found that these interactions increase fluorescence sensitivity. In the meantime, the synchronous fluorescence intensity revealed the interaction sites to be close to the tryptophan (Trp and tyrosine (Tyr residues of superoxide dismutase. Furthermore, molecular docking was applied to explore the binding mode between the ligands and the receptor. This suggested that HP-β-CD interacted with the B ring, G ring and the O ring and revealed that the lysine (Lys residues enter the nanocavity. It was concluded that the HP-β-CD caused specific conformational changes in SOD by non-covalent modification.

  3. MicroRNA transfection and AGO-bound CLIP-seq data sets reveal distinct determinants of miRNA action

    DEFF Research Database (Denmark)

    Wen, Jiayu; Parker, Brian J; Jacobsen, Anders

    2011-01-01

    the predictive effect of target flanking features. We observe distinct target determinants between expression-based and CLIP-based data. Target flanking features such as flanking region conservation are an important AGO-binding determinant-we hypothesize that CLIP experiments have a preference for strongly bound......Microarray expression analyses following miRNA transfection/inhibition and, more recently, Argonaute cross-linked immunoprecipitation (CLIP)-seq assays have been used to detect miRNA target sites. CLIP and expression approaches measure differing stages of miRNA functioning-initial binding of the mi...... miRNP-target interactions involving adjacent RNA-binding proteins that increase the strength of cross-linking. In contrast, seed-related features are major determinants in expression-based studies, but less so for CLIP-seq studies, and increased miRNA concentrations typical of transfection studies...

  4. Molecular simulations of lactose-bound and unbound forms of the FaeG adhesin reveal critical amino acids involved in sugar binding.

    Science.gov (United States)

    Baker, Joseph L; Jafri, Heba

    2016-11-01

    F4 fimbriae are protein filaments found in enterotoxigenic Escherichia coli cells and are implicated in the process of bacterial infection due to their function as bacterial adhesins. These filaments are comprised from several proteins, but the bacterial adhesin FaeG, which is a lactose-binding protein, is the major subunit comprising F4 fimbriae. Crystal structures for three variants of the FaeG protein were recently solved, including the ad variant of FaeG that was crystallized in complex with lactose. However, the dynamics of the FaeG protein bound to lactose have not been explored previously using molecular dynamics simulations. Therefore, in order to study the dynamical interactions between the FaeG ad variant and lactose, we have carried out the first all-atom molecular dynamics simulations of this system. We have also probed the role of crystallographic water molecules on the stability of lactose in the FaeG binding site, and have simulated seven FaeG mutants to probe the influence of amino acid substitutions on the ability of FaeG to bind lactose effectively. Our simulations agree well with experimental results for the influence of mutations on lactose binding, provide dynamical insights into the interactions of FaeG with lactose, and also suggest the possibility of additional regions of the FaeG protein that may act as secondary lactose binding sites. Copyright © 2016 Elsevier Inc. All rights reserved.

  5. Relationships between Cargo, Cell Penetrating Peptides and Cell Type for Uptake of Non-Covalent Complexes into Live Cells

    Directory of Open Access Journals (Sweden)

    Andrea-Anneliese Keller

    2013-02-01

    Full Text Available Modulating signaling pathways for research and therapy requires either suppression or expression of selected genes or internalization of proteins such as enzymes, antibodies, nucleotide binding proteins or substrates including nucleoside phosphates and enzyme inhibitors. Peptides, proteins and nucleotides are transported by fusing or conjugating them to cell penetrating peptides or by formation of non-covalent complexes. The latter is often preferred because of easy handling, uptake efficiency and auto-release of cargo into the live cell. In our studies complexes are formed with labeled or readily detectable cargoes for qualitative and quantitative estimation of their internalization. Properties and behavior of adhesion and suspension vertebrate cells as well as the protozoa Leishmania tarentolae are investigated with respect to proteolytic activity, uptake efficiency, intracellular localization and cytotoxicity. Our results show that peptide stability to membrane-bound, secreted or intracellular proteases varies between different CPPs and that the suitability of individual CPPs for a particular cargo in complex formation by non-covalent interactions requires detailed studies. Cells vary in their sensitivity to increasing concentrations of CPPs. Thus, most cells can be efficiently transduced with peptides, proteins and nucleotides with intracellular concentrations in the low micromole range. For each cargo, cell type and CPP the optimal conditions must be determined separately.

  6. Non-Covalent Fluorescent Labeling of Hairpin DNA Probe Coupled with Hybridization Chain Reaction for Sensitive DNA Detection.

    Science.gov (United States)

    Song, Luna; Zhang, Yonghua; Li, Junling; Gao, Qiang; Qi, Honglan; Zhang, Chengxiao

    2016-04-01

    An enzyme-free signal amplification-based assay for DNA detection was developed using fluorescent hairpin DNA probes coupled with hybridization chain reaction (HCR). The hairpin DNAs were designed to contain abasic sites in the stem moiety. Non-covalent labeling of the hairpin DNAs was achieved when a fluorescent ligand was bound to the abasic sites through hydrogen bonding with the orphan cytosine present on the complementary strand, accompanied by quench of ligand fluorescence. As a result, the resultant probes, the complex formed between the hairpin DNA and ligand, showed almost no fluorescence. Upon hybridization with target DNA, the probe underwent a dehybridization of the stem moiety containing an abasic site. The release of ligand from the abasic site to the solution resulted in an effective fluorescent enhancement, which can be used as a signal. Compared with a sensing system without HCR, a 20-fold increase in the sensitivity was achieved using the sensing system with HCR. The fluorescent intensity of the sensing system increased with the increase in target DNA concentration from 0.5 nM to 100 nM. A single mismatched target ss-DNA could be effectively discriminated from complementary target DNA. Genotyping of a G/C single-nucleotide polymorphism of polymerase chain reaction (PCR) products was successfully demonstrated with the sensing system. Therefore, integrating HCR strategy with non-covalent labeling of fluorescent hairpin DNA probes provides a sensitive and cost-effective DNA assay. © The Author(s) 2016.

  7. Scaled MP3 non-covalent interaction energies agree closely with accurate CCSD(T) benchmark data.

    Science.gov (United States)

    Pitonák, Michal; Neogrády, Pavel; Cerný, Jirí; Grimme, Stefan; Hobza, Pavel

    2009-01-12

    Scaled MP3 interaction energies calculated as a sum of MP2/CBS (complete basis set limit) interaction energies and scaled third-order energy contributions obtained in small or medium size basis sets agree very closely with the estimated CCSD(T)/CBS interaction energies for the 22 H-bonded, dispersion-controlled and mixed non-covalent complexes from the S22 data set. Performance of this so-called MP2.5 (third-order scaling factor of 0.5) method has also been tested for 33 nucleic acid base pairs and two stacked conformers of porphine dimer. In all the test cases, performance of the MP2.5 method was shown to be superior to the scaled spin-component MP2 based methods, e.g. SCS-MP2, SCSN-MP2 and SCS(MI)-MP2. In particular, a very balanced treatment of hydrogen-bonded compared to stacked complexes is achieved with MP2.5. The main advantage of the approach is that it employs only a single empirical parameter and is thus biased by two rigorously defined, asymptotically correct ab-initio methods, MP2 and MP3. The method is proposed as an accurate but computationally feasible alternative to CCSD(T) for the computation of the properties of various kinds of non-covalently bound systems.

  8. Non-covalent and reversible functionalization of carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Antonello Di Crescenzo

    2014-09-01

    Full Text Available Carbon nanotubes (CNTs have been proposed and actively explored as multipurpose innovative nanoscaffolds for applications in fields such as material science, drug delivery and diagnostic applications. Their versatile physicochemical features are nonetheless limited by their scarce solubilization in both aqueous and organic solvents. In order to overcome this drawback CNTs can be easily non-covalently functionalized with different dispersants. In the present review we focus on the peculiar hydrophobic character of pristine CNTs that prevent them to easily disperse in organic solvents. We report some interesting examples of CNTs dispersants with the aim to highlight the essential features a molecule should possess in order to act as a good carbon nanotube dispersant both in water and in organic solvents. The review pinpoints also a few examples of dispersant design. The last section is devoted to the exploitation of the major quality of non-covalent functionalization that is its reversibility and the possibility to obtain stimuli-responsive precipitation or dispersion of CNTs.

  9. [Noncovalent cation-π interactions--their role in nature].

    Science.gov (United States)

    Fink, Krzysztof; Boratyński, Janusz

    2014-11-07

    Non-covalent interactions play an extremely important role in organisms. The main non-covalent interactions in nature are: ion-ion interactions, dipole-dipole interactions, hydrogen bonds, and van der Waals interactions. A new kind of intermolecular interactions--cation-π interactions--is gaining increasing attention. These interactions occur between a cation and a π system. The main contributors to cation-π interactions are electrostatic, polarization and, to a lesser extent, dispersion interactions. At first, cation-π interactions were studied in a gas phase, with metal cation-aromatic system complexes. The characteristics of these complexes are as follows: an increase of cation atomic number leads to a decrease of interaction energy, and an increase of cation charge leads to an increase of interaction energy. Aromatic amino acids bind with metal cations mainly through interactions with their main chain. Nevertheless, cation-π interaction with a hydrophobic side chain significantly enhances binding energy. In water solutions most cations preferentially interact with water molecules rather than aromatic systems. Cation-π interactions occur in environments with lower accessibility to a polar solvent. Cation-π interactions can have a stabilizing role on the secondary, tertiary and quaternary structure of proteins. These interactions play an important role in substrate or ligand binding sites in many proteins, which should be taken into consideration when the screening of effective inhibitors for these proteins is carried out. Cation-π interactions are abundant and play an important role in many biological processes.

  10. Using PyMOL to Explore the Effects of pH on Noncovalent Interactions between Immunoglobulin G and Protein A: A Guided-Inquiry Biochemistry Activity.

    Science.gov (United States)

    Roche Allred, Zahilyn D; Tai, Heeyoung; Bretz, Stacey Lowery; Page, Richard C

    2017-11-01

    Students' understandings of foundational concepts such as noncovalent interactions, pH and pK a are crucial for success in undergraduate biochemistry courses. We developed a guided-inquiry activity to aid students in making connections between noncovalent interactions and pH/pK a . Students explore these concepts by examining the primary and tertiary structures of immunoglobulin G (IgG) and Protein A. Students use PyMOL, an open source molecular visualization application, to (1) identify hydrogen bonds and salt bridges between and within the proteins at physiological pH and (2) apply their knowledge of pH/pK a to association rate constant data for these proteins at pH 4 and pH 11. The laboratory activity was implemented within a one semester biochemistry laboratory for students majoring in allied health disciplines, engineering, and biological sciences. Several extensions for more advanced students are discussed. Students' overall performance highlighted their ability to successfully complete tasks such as labeling and identifying noncovalent interactions and revealed difficulties with analyzing noncovalent interactions under varying pH/pK a conditions. Students' evaluations after completing the activity indicated they felt challenged but also recognized the potential of the activity to help them gain meaningful understanding of the connections between noncovalent interactions, pH, pK a , and protein structure. © 2017 by The International Union of Biochemistry and Molecular Biology, 45(6):528-536, 2017. © 2017 The International Union of Biochemistry and Molecular Biology.

  11. Non-Covalent Organocatalyzed Domino Reactions Involving Oxindoles: Recent Advances

    Directory of Open Access Journals (Sweden)

    Tecla Gasperi

    2017-09-01

    Full Text Available The ubiquitous presence of spirooxindole architectures with several functionalities and stereogenic centers in bioactive molecules has been appealing for the development of novel methodologies seeking their preparation in high yields and selectivities. Expansion and refinement in the field of asymmetric organocatalysis have made possible the development of straightforward strategies that address these two requisites. In this review, we illustrate the current state-of-the-art in the field of spirooxindole synthesis through the use of non-covalent organocatalysis. We aim to provide a concise overview of very recent methods that allow to the isolation of unique, densely and diversified spirocyclic oxindole derivatives with high structural diversity via the use of cascade, tandem and domino processes.

  12. Structural dynamics of a noncovalent charge transfer complex from femtosecond stimulated Raman spectroscopy.

    Science.gov (United States)

    Fujisawa, Tomotsumi; Creelman, Mark; Mathies, Richard A

    2012-09-06

    Femtosecond stimulated Raman spectroscopy is used to examine the structural dynamics of photoinduced charge transfer within a noncovalent electron acceptor/donor complex of pyromellitic dianhydride (PMDA, electron acceptor) and hexamethylbenzene (HMB, electron donor) in ethylacetate and acetonitrile. The evolution of the vibrational spectrum reveals the ultrafast structural changes that occur during the charge separation (Franck-Condon excited state complex → contact ion pair) and the subsequent charge recombination (contact ion pair → ground state complex). The Franck-Condon excited state is shown to have significant charge-separated character because its vibrational spectrum is similar to that of the ion pair. The charge separation rate (2.5 ps in ethylacetate and ∼0.5 ps in acetonitrile) is comparable to solvation dynamics and is unaffected by the perdeuteration of HMB, supporting the dominant role of solvent rearrangement in charge separation. On the other hand, the charge recombination slows by a factor of ∼1.4 when using perdeuterated HMB, indicating that methyl hydrogen motions of HMB mediate the charge recombination process. Resonance Raman enhancement of the HMB vibrations in the complex reveals that the ring stretches of HMB, and especially the C-CH(3) deformations are the primary acceptor modes promoting charge recombination.

  13. Helical Polyacetylenes Induced via Noncovalent Chiral Interactions and Their Applications as Chiral Materials.

    Science.gov (United States)

    Maeda, Katsuhiro; Yashima, Eiji

    2017-08-01

    Construction of predominantly one-handed helical polyacetylenes with a desired helix sense utilizing noncovalent chiral interactions with nonracemic chiral guest compounds based on a supramolecular approach is described. As with the conventional dynamic helical polymers possessing optically active pendant groups covalently bonded to the polymer chains, this noncovalent helicity induction system can show significant chiral amplification phenomena, in which the chiral information of the nonracemic guests can transfer with high cooperativity through noncovalent bonding interactions to induce an almost single-handed helical conformation in the polymer backbone. An intriguing "memory effect" of the induced macromolecular helicity is observed for some polyacetylenes, which means that the helical conformations induced in dynamic helical polyacetylene can be transformed into metastable static ones by tuning their helix-inversion barriers. Potential applications of helical polyacetylenes with controlled helix sense constructed by the "noncovalent helicity induction and/or memory effect" as chiral materials are also described.

  14. Perceptron Mistake Bounds

    OpenAIRE

    Mohri, Mehryar; Rostamizadeh, Afshin

    2013-01-01

    We present a brief survey of existing mistake bounds and introduce novel bounds for the Perceptron or the kernel Perceptron algorithm. Our novel bounds generalize beyond standard margin-loss type bounds, allow for any convex and Lipschitz loss function, and admit a very simple proof.

  15. Tuning the electronic structure and transport properties of graphene by noncovalent functionalization: effects of organic donor, acceptor and metal atoms

    International Nuclear Information System (INIS)

    Zhang Yonghui; Zhou Kaige; Xie Kefeng; Zeng Jing; Zhang Haoli; Peng Yong

    2010-01-01

    Using density functional theory and nonequilibrium Green's function (NEGF) formalism, we have theoretically investigated the binding of organic donor, acceptor and metal atoms on graphene sheets, and revealed the effects of the different noncovalent functionalizations on the electronic structure and transport properties of graphene. The adsorptions of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and tetrathiafulvalene (TTF) induce hybridization between the molecular levels and the graphene valence bands, and transform the zero-gap semiconducting graphene into a metallic graphene. However, the current versus voltage (I-V) simulation indicates that the noncovalent modifications by organic molecules are not sufficient to significantly alter the transport property of the graphene for sensing applications. We found that the molecule/graphene interaction could be dramatically enhanced by introducing metal atoms to construct molecule/metal/graphene sandwich structures. A chemical sensor based on iron modified graphene shows a sensitivity two orders of magnitude higher than that of pristine graphene. The results of this work could help to design novel graphene-based sensing or switching devices.

  16. Electromagnetic interference shielding and thermal properties of non-covalently functionalized reduced graphene oxide/epoxy composites

    Directory of Open Access Journals (Sweden)

    Suman Chhetri

    2016-12-01

    Full Text Available Graphene oxide (GO was non-covalently functionalized using sulfanilic acid azocromotrop (SAC followed by hydrazine reduction to achieve SAC functionalized reduced GO (SAC-rGO. Fourier transform infrared spectra analysis and electrical conductivity measurements confirmed the successful functionlization and reduction of GO. The electrical conductivity of ~515 S•m−1 for SAC-rGO was recorded. The non-covalently functionalized reduced GO was subsequently dispersed in epoxy matrix at the loading level of 0.3 to 0.5 wt% to investigate its electromagnetic interference (EMI shielding properties. The morphological and structural characterization of the SAC-rGO/epoxy composites was carried out using X-ray diffraction and Transmission electron microscopy analysis, which revealed the good dispersion of SAC-rGO in the epoxy. The SAC-rGO/epoxy composites showed the EMI shielding of −22.6 dB at the loading of 0.5 wt% SAC-rGO. Dynamical mechanical properties of the composites were studied to establish the reinforcing competency of the SAC-rGO. The storage modulus of the composites was found to increase within the studied temperature. Thermal stability of pure epoxy and its composites were compared by selecting the temperatures at 10 and 50% weight loss, respectively.

  17. Noncovalent Interactions between Dopamine and Regular and Defective Graphene.

    Science.gov (United States)

    Fernández, Ana C Rossi; Castellani, Norberto J

    2017-08-05

    The role of noncovalent interactions in the adsorption of biological molecules on graphene is a subject of fundamental interest regarding the use of graphene as a material for sensing and drug delivery. The adsorption of dopamine on regular graphene and graphene with monovacancies (GV) is theoretically studied within the framework of density functional theory. Several adsorption modes are considered, and notably those in which the dopamine molecule is oriented parallel or quasi-parallel to the surface are the more stable. The adsorption of dopamine on graphene implies an attractive interaction of a dispersive nature that competes with Pauli repulsion between the occupied π orbitals of the dopamine ring and the π orbitals of graphene. If dopamine adsorbs at the monovacancy in the A-B stacking mode, a hydrogen bond is produced between one of the dopamine hydroxy groups and one carbon atom around the vacancy. The electronic charge redistribution due to adsorption is consistent with an electronic drift from the graphene or GV surface to the dopamine molecule. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Circuit lower bounds in bounded arithmetics

    Czech Academy of Sciences Publication Activity Database

    Pich, Ján

    2015-01-01

    Roč. 166, č. 1 (2015), s. 29-45 ISSN 0168-0072 R&D Projects: GA AV ČR IAA100190902 Keywords : bounded arithmetic * circuit lower bounds Subject RIV: BA - General Mathematics Impact factor: 0.582, year: 2015 http://www.sciencedirect.com/science/article/pii/S0168007214000888

  19. Nicked apomyoglobin: a noncovalent complex of two polypeptide fragments comprising the entire protein chain.

    Science.gov (United States)

    Musi, Valeria; Spolaore, Barbara; Picotti, Paola; Zambonin, Marcello; De Filippis, Vincenzo; Fontana, Angelo

    2004-05-25

    Limited proteolysis of the 153-residue chain of horse apomyoglobin (apoMb) by thermolysin results in the selective cleavage of the peptide bond Pro88-Leu89. The N-terminal (residues 1-88) and C-terminal (residues 89-153) fragments of apoMb were isolated to homogeneity and their conformational and association properties investigated in detail. Far-UV circular dichroism (CD) measurements revealed that both fragments in isolation acquire a high content of helical secondary structure, while near-UV CD indicated the absence of tertiary structure. A 1:1 mixture of the fragments leads to a tight noncovalent protein complex (1-88/89-153, nicked apoMb), characterized by secondary and tertiary structures similar to those of intact apoMb. The apoMb complex binds heme in a nativelike manner, as given by CD measurements in the Soret region. Second-derivative absorption spectra in the 250-300 nm region provided evidence that the degree of exposure of Tyr residues in the nicked species is similar to that of the intact protein at neutral pH. Also, the microenvironment of Trp residues, located in positions 7 and 14 of the 153-residue chain of the protein, is similar in both protein species, as given by fluorescence emission data. Moreover, in analogy to intact apoMb, the nicked protein binds the hydrophobic dye 1-anilinonaphthalene-8-sulfonate (ANS). Taken together, our results indicate that the two proteolytic fragments 1-88 and 89-153 of apoMb adopt partly folded states characterized by sufficiently nativelike conformational features that promote their specific association and mutual stabilization into a nicked protein species much resembling in its structural features intact apoMb. It is suggested that the formation of a noncovalent complex upon fragment complementation can mimic the protein folding process of the entire protein chain, with the difference that the folding of the complementary fragments is an intermolecular process. In particular, this study emphasizes the

  20. Thermometric sensing of nitrofurantoin by noncovalently imprinted polymers containing two complementary functional monomers.

    Science.gov (United States)

    Athikomrattanakul, Umporn; Gajovic-Eichelmann, Nenad; Scheller, Frieder W

    2011-10-15

    Molecularly imprinted polymers (MIPs) for nitrofurantoin (NFT) recognition addressing in parallel of two complementary functional groups were created using a noncovalent imprinting approach. Specific tailor-made functional monomers were synthesized: a diaminopyridine derivative as the receptor for the imide residue and three (thio)urea derivatives for the interaction with the nitro group of NFT. A significantly improved binding of NFT to the new MIPs was revealed from the imprinting factor, efficiency of binding, affinity constants and maximum binding number as compared to previously reported MIPs, which addressed either the imide or the nitro residue. Substances possessing only one functionality (either the imide group or nitro group) showed significantly weaker binding to the new imprinted polymers than NFT. However, the compounds lacking both functionalities binds extremely weak to all imprinted polymers. The new imprinted polymers were applied in a flow-through thermistor in organic solvent for the first time. The MIP-thermistor allows the detection of NFT down to a concentration of 5 μM in acetonitrile + 0.2% dimethyl sulfoxide (DMSO). The imprinting factor of 3.91 at 0.1 mM of NFT as obtained by thermistor measurements is well comparable to the value obtained by batch binding experiments. © 2011 American Chemical Society

  1. Non-covalent interactions of cadmium sulphide and gold nanoparticles with DNA

    Science.gov (United States)

    Atay, Z.; Biver, T.; Corti, A.; Eltugral, N.; Lorenzini, E.; Masini, M.; Paolicchi, A.; Pucci, A.; Ruggeri, G.; Secco, F.; Venturini, M.

    2010-08-01

    Mercaptoethanol-capped CdS nanoparticles (CdSnp) and monohydroxy-(1-mercaptoundec-11-yl)tetraethylene-glycol-capped Au nanoparticles (Aunp) were synthesised, characterised and their interactions with DNA were investigated. Aunp are stable in different aqueous solvents, whereas CdSnp do precipitate in 0.1 M NaCl and form two different cluster types in 0.1 M NaNO3. As regards the CdSnp/DNA interaction, absorbance and fluorescence titrations, ethidium bromide displacement assays and gel electrophoresis experiments indicate that a non-covalent interaction between DNA and the CdSnp external surface does take place. The binding constant was evaluated to be equal to (2.2 ± 0.5) × 105 M-1. On the contrary, concerning Aunp, no direct interaction with DNA could be observed. Possible interaction with serum albumin was also checked, but no effects could be observed for either CdSnp or Aunp. Finally, short-time exposure of cultured cells to nanoparticles revealed the ability of CdSnp to enter the cells and allocate both in cytosol and nucleus, thus promoting cell proliferation at low concentration ( p resulted in a significant inhibition of cell growth, accompanied by apoptotic cell death. Aunp neither enter the cells, nor do affect cell proliferation. In conclusion, our data indicate that CdSnp can strongly interact with living cells and nucleic acid while no effects or interactions were observed for Aunp.

  2. Scattering by bound nucleons

    International Nuclear Information System (INIS)

    Tezuka, Hirokazu.

    1984-10-01

    Scattering of a particle by bound nucleons is discussed. Effects of nucleons that are bound in a nucleus are taken as a structure function. The way how to calculate the structure function is given. (author)

  3. Thermal solid-state Z/E isomerization of 2-alkylidene-4-oxothiazolidines: effects of non-covalent interactions

    Directory of Open Access Journals (Sweden)

    ZDRAVKO DŽAMBASKI

    2011-03-01

    Full Text Available Configurational isomerization of stereo-defined 5-substituted and unsubstituted 2-alkylidene-4-oxothiazolidines (1 in the solid state, giving the Z/E mixtures in various ratios, was investigated by 1H-NMR spectroscopy, X-ray powder crystallography and differential scanning calorimetry (DSC. The Z/E composition can be rationalized in terms of non-covalent interactions, involving intermolecular and intramolecular hydrogen bonding and directional non-bonded 1,5-type S×××O interactions. X-Ray powder crystallography, using selected crystalline (Z-4-oxothiazolidine substrates, revealed transformation to the amorphous state during the irreversible Z®E process. A correlation between previous results on the Z/E isomerization in solution and now in the solid state was established.

  4. Vanillyl alcohol oxidases produced in Komagataella phaffii contain a highly stable non-covalently bound anionic FAD semiquinone

    NARCIS (Netherlands)

    Gygli, G.A.; Berkel, van W.J.H.

    2017-01-01

    Vanillyl alcohol oxidase (VAO) from Penicillium simplicissimum is a covalent flavoprotein that has emerged as a promising biocatalyst for the production of aromatic fine chemicals such as vanillin, coniferyl alcohol and enantiopure 1-(4’-hydroxyphenyl) alcohols. The largescale production of this

  5. Noncovalent Attachment of PbS Quantum Dots to Single- and Multiwalled Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Anirban Das

    2014-01-01

    Full Text Available Attachment of PbS quantum dots (QD to single-walled carbon nanotubes (SWNT and multiwalled carbon nanotubes (MWCNT is described; wherein commercially obtained PbS-QD of size 2.7 nm, stabilized by oleic acid, are added to a suspension of single- or multiwalled carbon nanotubes (CNT prefunctionalized noncovalently with 1,2-benzenedimethanethiol (1,2-BDMT in ethanol. The aromatic part of 1,2-BDMT attaches to the CNT by π-π stacking interactions, noncovalently functionalizing the CNT. The thiol part of the 1,2-BDMT on the functionalized CNT replaces oleic acid on the surface of the QD facilitating the noncovalent attachment of the QD to the CNT. The composites were characterized by TEM and FTIR spectroscopy. Quenching of NIR fluorescence of the PbS-QD on attachment to the carbon nanotubes (CNT was observed, indicating FRET from the QD to the CNT.

  6. Physical Uncertainty Bounds (PUB)

    Energy Technology Data Exchange (ETDEWEB)

    Vaughan, Diane Elizabeth [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Preston, Dean L. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-03-19

    This paper introduces and motivates the need for a new methodology for determining upper bounds on the uncertainties in simulations of engineered systems due to limited fidelity in the composite continuum-level physics models needed to simulate the systems. We show that traditional uncertainty quantification methods provide, at best, a lower bound on this uncertainty. We propose to obtain bounds on the simulation uncertainties by first determining bounds on the physical quantities or processes relevant to system performance. By bounding these physics processes, as opposed to carrying out statistical analyses of the parameter sets of specific physics models or simply switching out the available physics models, one can obtain upper bounds on the uncertainties in simulated quantities of interest.

  7. Atomic Ensemble Effects and Non-Covalent Interactions at the Electrode–Electrolyte Interface

    Directory of Open Access Journals (Sweden)

    Angel Cuesta

    2016-09-01

    Full Text Available Cyanide-modified Pt(111 electrodes have been recently employed to study atomic ensemble effects in electrocatalysis. This work, which will be briefly reviewed, reveals that the smallest site required for methanol dehydrogenation and formic acid dehydration is composed of three contiguous Pt atoms. By blocking these trigonal sites, the specific adsorption of anions, such as sulfate and phosphate, can be inhibited, thus increasing the rate of oxygen reduction reaction by one order of magnitude or more. Moreover, alkali metal cations affect hydrogen adsorption on cyanide-modified Pt(111. This effect is attributed to the non-covalent interactions at the electrical double layer between specifically adsorbed anions or dipoles and the alkali metal cations. A systematic investigation is conducted on the effect of the concentration of alkali metal cations. Accordingly, a simple model that reproduces the experimental observations accurately and enables the understanding of the trends in the strength of the interaction between M+ and CNad when moving from Li+ to Cs+, as well as the deviations from the expected trends, is developed. This simple model can also explain the occurrence of super-Nernstian shifts of the equilibrium potential of interfacial proton-coupled electron transfers. Therefore, the model can be generally applied to explain quantitatively the effect of cations on the properties of the electrical double layer. The recently reported effects of alkali metal cations on several electrocatalytic reactions must be mediated by the interaction between these cations and chemisorbed species. As these interactions seem to be adequately and quantitatively described by our model, we expect the model to also be useful to describe, explain, and potentially exploit these effects.

  8. Non-covalent interactions of cadmium sulphide and gold nanoparticles with DNA

    Energy Technology Data Exchange (ETDEWEB)

    Atay, Z. [Bogazici University, Department of Chemistry (Turkey); Biver, T., E-mail: tarita@dcci.unipi.i [Universita di Pisa, Dipartimento di Chimica e Chimica Industriale (Italy); Corti, A. [Universita di Pisa, Dipartimento di Patologia Sperimentale BMIE (Italy); Eltugral, N. [Universita di Pisa, Dipartimento di Chimica e Chimica Industriale (Italy); Lorenzini, E.; Masini, M.; Paolicchi, A. [Universita di Pisa, Dipartimento di Patologia Sperimentale BMIE (Italy); Pucci, A.; Ruggeri, G.; Secco, F.; Venturini, M. [Universita di Pisa, Dipartimento di Chimica e Chimica Industriale (Italy)

    2010-08-15

    Mercaptoethanol-capped CdS nanoparticles (CdS{sub np}) and monohydroxy-(1-mercaptoundec-11-yl)tetraethylene-glycol-capped Au nanoparticles (Au{sub np}) were synthesised, characterised and their interactions with DNA were investigated. Au{sub np} are stable in different aqueous solvents, whereas CdS{sub np} do precipitate in 0.1 M NaCl and form two different cluster types in 0.1 M NaNO{sub 3}. As regards the CdS{sub np}/DNA interaction, absorbance and fluorescence titrations, ethidium bromide displacement assays and gel electrophoresis experiments indicate that a non-covalent interaction between DNA and the CdS{sub np} external surface does take place. The binding constant was evaluated to be equal to (2.2 {+-} 0.5) x 10{sup 5} M{sup -1}. On the contrary, concerning Au{sub np}, no direct interaction with DNA could be observed. Possible interaction with serum albumin was also checked, but no effects could be observed for either CdS{sub np} or Au{sub np}. Finally, short-time exposure of cultured cells to nanoparticles revealed the ability of CdS{sub np} to enter the cells and allocate both in cytosol and nucleus, thus promoting cell proliferation at low concentration (p < 0.005), while longer-time exposure resulted in a significant inhibition of cell growth, accompanied by apoptotic cell death. Au{sub np} neither enter the cells, nor do affect cell proliferation. In conclusion, our data indicate that CdS{sub np} can strongly interact with living cells and nucleic acid while no effects or interactions were observed for Au{sub np}.

  9. Crystal structures of Mycobacterium tuberculosis GlgE and complexes with non-covalent inhibitors

    Energy Technology Data Exchange (ETDEWEB)

    Lindenberger, Jared J.; Veleti, Sri Kumar; Wilson, Brittney N.; Sucheck, Steven J.; Ronning, Donald R. (Toledo)

    2015-08-06

    GlgE is a bacterial maltosyltransferase that catalyzes the elongation of a cytosolic, branched α-glucan. In Mycobacterium tuberculosis (M. tb), inactivation of GlgE (Mtb GlgE) results in the rapid death of the organism due to a toxic accumulation of the maltosyl donor, maltose-1-phosphate (M1P), suggesting that GlgE is an intriguing target for inhibitor design. In this study, the crystal structures of the Mtb GlgE in a binary complex with maltose and a ternary complex with maltose and a maltosyl-acceptor molecule, maltohexaose, were solved to 3.3 Å and 4.0 Å, respectively. The maltohexaose structure reveals a dominant site for α-glucan binding. To obtain more detailed interactions between first generation, non-covalent inhibitors and GlgE, a variant Streptomyces coelicolor GlgEI (Sco GlgEI-V279S) was made to better emulate the Mtb GlgE M1P binding site. The structure of Sco GlgEI-V279S complexed with α-maltose-C-phosphonate (MCP), a non-hydrolyzable substrate analogue, was solved to 1.9 Å resolution, and the structure of Sco GlgEI-V279S complexed with 2,5-dideoxy-3-O-α-D-glucopyranosyl-2,5-imino-D-mannitol (DDGIM), an oxocarbenium mimic, was solved to 2.5 Å resolution. These structures detail important interactions that contribute to the inhibitory activity of these compounds, and provide information on future designs that may be exploited to improve upon these first generation GlgE inhibitors.

  10. Photon virtual bound state

    International Nuclear Information System (INIS)

    Inoue, J.; Ohtaka, K.

    2004-01-01

    We study virtual bound states in photonics, which are a vectorial extension of electron virtual bound states. The condition for these states is derived. It is found that the Mie resonant state which satisfies the condition that the size parameter is less than the angular momentum should be interpreted as a photon virtual bound state. In order to confirm the validity of the concept, we compare the photonic density of states, the width of which represents the lifetime of the photon virtual bound states, with numerical results

  11. The DMM Bound

    DEFF Research Database (Denmark)

    Emiris, Ioannis Z.; Mourrain, Bernard; Tsigaridas, Elias

    2010-01-01

    ) resultant by means of mixed volume, as well as recent advances on aggregate root bounds for univariate polynomials, and are applicable to arbitrary positive dimensional systems. We improve upon Canny's gap theorem [7] by a factor of O(dn-1), where d bounds the degree of the polynomials, and n is the number...... bound on the number of steps that subdivision-based algorithms perform in order to isolate all real roots of a polynomial system. This leads to the first complexity bound of Milne's algorithm [22] in 2D....

  12. Photochemistry of triarylmethane dyes bound to proteins

    Science.gov (United States)

    Indig, Guilherme L.

    1996-04-01

    Triarylmethanes represent a class of cationic dyes whose potential as photosensitizers for use in photodynamic therapy of neoplastic diseases has never been comprehensively evaluated. Here, the laser-induced photodecomposition of three triarylmethane dyes, crystal violet, ethyl violet, and malachite green, non-covalently bound to bovine serum albumin (a model biological target) was investigated. Upon laser excitation at 532 nm, the bleaching of the corresponding dye-protein molecular complexes follows spectroscopic patterns that suggest the formation of reduced forms of the dyes as major reaction photoproducts. That implies that an electron or hydrogen atom transfer from the protein to the dye's moiety within the guest-host complex is the first step of the photobleaching process. Since the availability of dissolved molecular oxygen was not identified as a limiting factor for the phototransformations to occur, these dyes can be seen as potential phototherapeutic agents for use in hypoxic areas of tumors. These triarylmethane dyes strongly absorb at relatively long wavelengths (absorption maximum around 600 nm; (epsilon) max approximately equals 105 M-1 cm-1), and only minor changes in their absorption characteristics are observed upon binding to the protein. However the binding event leads to a remarkable increase in their fluorescence quantum yield and photoreactivity.

  13. Bounded Gaussian process regression

    DEFF Research Database (Denmark)

    Jensen, Bjørn Sand; Nielsen, Jens Brehm; Larsen, Jan

    2013-01-01

    We extend the Gaussian process (GP) framework for bounded regression by introducing two bounded likelihood functions that model the noise on the dependent variable explicitly. This is fundamentally different from the implicit noise assumption in the previously suggested warped GP framework. We...... with the proposed explicit noise-model extension....

  14. Bounded Intention Planning Revisited

    OpenAIRE

    Sievers Silvan; Wehrle Martin; Helmert Malte

    2014-01-01

    Bounded intention planning provides a pruning technique for optimal planning that has been proposed several years ago. In addition partial order reduction techniques based on stubborn sets have recently been investigated for this purpose. In this paper we revisit bounded intention planning in the view of stubborn sets.

  15. Control of structural isomerism in noncovalent hydrogen-bonded assemblies using peripheral chiral information

    NARCIS (Netherlands)

    Prins, L.J.; Jolliffe, K.A.; Hulst, A.J.R.L.; Timmerman, P.; Reinhoudt, David

    2000-01-01

    The results of a systematic study of the structural isomerism in more than 30 noncovalent hydrogen-bonded assemblies are described. These dynamic assemblies, composed of three calix[4]arene dimelamines and six barbiturates/cyanurates, can be present in three isomeric forms with either D3, C3h, or Cs

  16. Stabilization of Proteins and Noncovalent Protein Complexes during Electrospray Ionization by Amino Acid Additives.

    Science.gov (United States)

    Zhang, Hua; Lu, Haiyan; Chingin, Konstantin; Chen, Huanwen

    2015-07-21

    Ionization of proteins and noncovalent protein complexes with minimal disturbance to their native structure presents a great challenge for biological mass spectrometry (MS). In living organisms, the native structure of intracellular proteins is commonly stabilized by solute amino acids (AAs) accumulated in cells at very high concentrations. Inspired by nature, we hypothesized that AAs could also pose a stabilizing effect on the native structure of proteins and noncovalent protein complexes during ionization. To test this hypothesis, here we explored MS response for various protein complexes upon the addition of free AAs at mM concentrations into the electrospray ionization (ESI) solution. Thermal activation of ESI droplets in the MS inlet capillary was employed as a model destabilizing factor during ionization. Our results indicate that certain AAs, in particular proline (Pro), pose considerable positive effect on the stability of noncovalent protein complexes in ESI-MS without affecting the signal intensity of protein ions and original protein-ligand equilibrium, even when added at the 20 mM concentration. The data suggest that the degree of protein stabilization is primarily determined by the osmolytic and ampholytic characteristics of AA solutes. The highest stability and visibility of noncovalent protein complexes in ESI-MS are achieved using AA additives with neutral isoelectric point, moderate proton affinity, and unfavorable interaction with the native protein state. Overall, our results indicate that the simple addition of free amino acids into the working solution can notably improve the stability and accuracy of protein analysis by native ESI-MS.

  17. Are Noncovalent Interactions an Achilles Heel in Chemistry Education? A Comparison of Instructional Approaches

    Science.gov (United States)

    Williams, Leah C.; Underwood, Sonia M.; Klymkowsky, Michael W.; Cooper, Melanie M.

    2015-01-01

    Intermolecular forces (IMFs), or more broadly, noncovalent interactions either within or between molecules, are central to an understanding of a wide range of chemical and biological phenomena. In this study, we present a multiyear, multi-institutional, longitudinal comparison of how students enrolled in traditional general chemistry courses and…

  18. Catalyst recycling via specific non-covalent adsorption on modified silicas

    NARCIS (Netherlands)

    Kluwer, A.M.; Simons, C.; Knijnenburg, Q.; van der Vlugt, J.I.; de Bruin, B.; Reek, J.N.H.

    2013-01-01

    This article describes a new strategy for the recycling of a homogeneous hydroformylation catalyst, by selective adsorption of the catalyst to tailor-made supports after a batchwise reaction. The separation of the catalyst from the product mixture is based on selective non-covalent supramolecular

  19. Nature and consequences of non-covalent interactions between flavonoids and macronutrients in foods.

    Science.gov (United States)

    Bordenave, Nicolas; Hamaker, Bruce R; Ferruzzi, Mario G

    2014-01-01

    Many of the potential health benefits of flavonoids have been associated with their specific chemical and biological properties including their ability to interact and bind non-covalently to macronutrients in foods. While flavonoid-protein interactions and binding have been the subject of intensive study, significantly less is understood about non-covalent interactions with carbohydrates and lipids. These interactions with macronutrients are likely to impact both the flavonoid properties in foods, such as their radical scavenging activity, and the food or beverage matrix itself, including their taste, texture and other sensorial properties. Overall, non-covalent binding of flavonoids with macronutrients is primarily driven by van der Waals interactions. From the flavonoid perspective, these interactions are modulated by characteristics such as degree of polymerization, molecular flexibility, number of external hydroxyl groups, or number of terminal galloyl groups. From the macronutrient standpoint, electrostatic and ionic interactions are generally predominant with carbohydrates, while hydrophobic interactions are generally predominant with lipids and mainly limited to interactions with flavonols. All of these interactions are involved in flavonoid-protein interactions. While primarily associated with undesirable characteristics in foods and beverages, such as astringency, negative impact on macronutrient digestibility and hazing, more recent efforts have attempted to leverage these interactions to develop controlled delivery systems or strategies to enhance flavonoids bioavailability. This paper aims at reviewing the fundamental bases for non-covalent interactions, their occurrence in food and beverage systems and their impact on the physico-chemical, organoleptic and some nutritional properties of food.

  20. Non-covalently functionalized carbon nanostructures for synthesizing carbon-based hybrid nanomaterials.

    Science.gov (United States)

    Li, Haiqing; Song, Sing I; Song, Ga Young; Kim, Il

    2014-02-01

    Carbon nanostructures (CNSs) such as carbon nanotubes, graphene sheets, and nanodiamonds provide an important type of substrate for constructing a variety of hybrid nanomaterials. However, their intrinsic chemistry-inert surfaces make it indispensable to pre-functionalize them prior to immobilizing additional components onto their surfaces. Currently developed strategies for functionalizing CNSs include covalent and non-covalent approaches. Conventional covalent treatments often damage the structure integrity of carbon surfaces and adversely affect their physical properties. In contrast, the non-covalent approach offers a non-destructive way to modify CNSs with desired functional surfaces, while reserving their intrinsic properties. Thus far, a number of surface modifiers including aromatic compounds, small-molecular surfactants, amphiphilic polymers, and biomacromolecules have been developed to non-covalently functionalize CNS surfaces. Mediated by these surface modifiers, various functional components such as organic species and inorganic nanoparticles were further decorated onto their surfaces, resulting in versatile carbon-based hybrid nanomaterials with broad applications in chemical engineering and biomedical areas. In this review, the recent advances in the generation of such hybrid nanostructures based on non-covalently functionalized CNSs will be reviewed.

  1. Enhanced mechanical properties of epoxy nanocomposites by mixing noncovalently functionalized boron nitride nanoflakes.

    Science.gov (United States)

    Lee, Dongju; Song, Sung Ho; Hwang, Jaewon; Jin, Sung Hwan; Park, Kwang Hyun; Kim, Bo Hyun; Hong, Soon Hyung; Jeon, Seokwoo

    2013-08-12

    The influence of surface modifications on the mechanical properties of epoxy-hexagonal boron nitride nanoflake (BNNF) nanocomposites is investigated. Homogeneous distributions of boron nitride nanoflakes in a polymer matrix, preserving intrinsic material properties of boron nitride nanoflakes, is the key to successful composite applications. Here, a method is suggested to obtain noncovalently functionalized BNNFs with 1-pyrenebutyric acid (PBA) molecules and to synthesize epoxy-BNNF nanocomposites with enhanced mechanical properties. The incorporation of noncovalently functionalized BNNFs into epoxy resin yields an elastic modulus of 3.34 GPa, and 71.9 MPa ultimate tensile strength at 0.3 wt%. The toughening enhancement is as high as 107% compared to the value of neat epoxy. The creep strain and the creep compliance of the noncovalently functionalized BNNF nanocomposite is significantly less than the neat epoxy and the nonfunctionalized BNNF nanocomposite. Noncovalent functionalization of BNNFs is effective to increase mechanical properties by strong affinity between the fillers and the matrix. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Combining covalent and noncovalent cross-linking: a novel terpolymer for two-step curing applications

    NARCIS (Netherlands)

    El-Ghayoury, A.; Hofmeier, H.; Ruiter, de B.; Schubert, U.S.

    2003-01-01

    A terpolymer of poly(butyl acrylate) bearing terpyridine as well as oxetane units was synthesized by free radical polymerization and characterized using NMR, UV-vis, and GPC. Subsequently, UV-vis experiments indicated clearly a noncovalent cross-linking of the terpyridine moieties by addition of

  3. Bounding species distribution models

    Directory of Open Access Journals (Sweden)

    Thomas J. STOHLGREN, Catherine S. JARNEVICH, Wayne E. ESAIAS,Jeffrey T. MORISETTE

    2011-10-01

    Full Text Available Species distribution models are increasing in popularity for mapping suitable habitat for species of management concern. Many investigators now recognize that extrapolations of these models with geographic information systems (GIS might be sensitive to the environmental bounds of the data used in their development, yet there is no recommended best practice for “clamping” model extrapolations. We relied on two commonly used modeling approaches: classification and regression tree (CART and maximum entropy (Maxent models, and we tested a simple alteration of the model extrapolations, bounding extrapolations to the maximum and minimum values of primary environmental predictors, to provide a more realistic map of suitable habitat of hybridized Africanized honey bees in the southwestern United States. Findings suggest that multiple models of bounding, and the most conservative bounding of species distribution models, like those presented here, should probably replace the unbounded or loosely bounded techniques currently used [Current Zoology 57 (5: 642–647, 2011].

  4. Bounding Species Distribution Models

    Science.gov (United States)

    Stohlgren, Thomas J.; Jarnevich, Cahterine S.; Morisette, Jeffrey T.; Esaias, Wayne E.

    2011-01-01

    Species distribution models are increasing in popularity for mapping suitable habitat for species of management concern. Many investigators now recognize that extrapolations of these models with geographic information systems (GIS) might be sensitive to the environmental bounds of the data used in their development, yet there is no recommended best practice for "clamping" model extrapolations. We relied on two commonly used modeling approaches: classification and regression tree (CART) and maximum entropy (Maxent) models, and we tested a simple alteration of the model extrapolations, bounding extrapolations to the maximum and minimum values of primary environmental predictors, to provide a more realistic map of suitable habitat of hybridized Africanized honey bees in the southwestern United States. Findings suggest that multiple models of bounding, and the most conservative bounding of species distribution models, like those presented here, should probably replace the unbounded or loosely bounded techniques currently used [Current Zoology 57 (5): 642-647, 2011].

  5. SHARP ENTRYWISE PERTURBATION BOUNDS FOR MARKOV CHAINS.

    Science.gov (United States)

    Thiede, Erik; VAN Koten, Brian; Weare, Jonathan

    For many Markov chains of practical interest, the invariant distribution is extremely sensitive to perturbations of some entries of the transition matrix, but insensitive to others; we give an example of such a chain, motivated by a problem in computational statistical physics. We have derived perturbation bounds on the relative error of the invariant distribution that reveal these variations in sensitivity. Our bounds are sharp, we do not impose any structural assumptions on the transition matrix or on the perturbation, and computing the bounds has the same complexity as computing the invariant distribution or computing other bounds in the literature. Moreover, our bounds have a simple interpretation in terms of hitting times, which can be used to draw intuitive but rigorous conclusions about the sensitivity of a chain to various types of perturbations.

  6. Organically bound tritium

    International Nuclear Information System (INIS)

    Diabate, S.; Strack, S.

    1993-01-01

    Tritium released into the environment may be incorporated into organic matter. Organically bound tritium in that case will show retention times in organisms that are considerably longer than those of tritiated water which has significant consequences on dose estimates. This article reviews the most important processes of organically bound tritium production and transport through food networks. Metabolic reactions in plant and animal organisms with tritiated water as a reaction partner are of great importance in this respect. The most important production process, in quantitative terms, is photosynthesis in green plants. The translocation of organically bound tritium from the leaves to edible parts of crop plants should be considered in models of organically bound tritium behavior. Organically bound tritium enters the human body on several pathways, either from the primary producers (vegetable food) or at a higher tropic level (animal food). Animal experiments have shown that the dose due to ingestion of organically bound tritium can be up to twice as high as a comparable intake of tritiated water in gaseous or liquid form. In the environment, organically bound tritium in plants and animals is often found to have higher specific tritium concentrations than tissue water. This is not due to some tritium enrichment effects but to the fact that no equilibrium conditions are reached under natural conditions. 66 refs

  7. Deeply bound pionic atom

    International Nuclear Information System (INIS)

    Toki, Hiroshi; Yamazaki, Toshimitsu

    1989-01-01

    The standard method of pionic atom formation does not produce deeply bound pionic atoms. A study is made on the properties of deeply bound pionic atom states by using the standard pion-nucleus optical potential. Another study is made to estimate the cross sections of the formation of ls pionic atom states by various methods. The pion-nucleus optical potential is determined by weakly bound pionic atom states and pion nucleus scattering. Although this potential may not be valid for deeply bound pionic atoms, it should provide some hint on binding energies and level widths of deeply bound states. The width of the ls state comes out to be 0.3 MeV and is well separated from the rest. The charge dependence of the ls state is investigated. The binding energies and the widths increase linearly with Z azbove a Z of 30. The report then discusses various methods to populate deeply bound pionic atoms. In particular, 'pion exchange' reactions are proposed. (n, pπ) reaction is discussed first. The cross section is calculated by assuming the in- and out-going nucleons on-shell and the produced pion in (n1) pionic atom states. Then, (n, dπ - ) cross sections are estimated. (p, 2 Heπ - ) reaction would have cross sections similar to the cross section of (n, dπ - ) reaction. In conclusion, it seems best to do (n, p) experiment on heavy nuclei for deeply bound pionic atom. (Nogami, K.)

  8. Bounded Rationality and Budgeting

    OpenAIRE

    Ibrahim, Mukdad

    2016-01-01

    This article discusses the theory of bounded rationality which had been introduced by Herbert Simon in the 1950s. Simon introduced the notion of bounded rationality stating that while decision-makers strive for rationality, they are limited by the effect of the environment, their information process capacity and by the constraints on their information storage and retrieval capabilities. Moreover, this article tries to specifically blend this notion into budgeting, using the foundations of inc...

  9. Inhibitory profiles of spices against free and protein-bound heterocyclic amines of roast beef patties as revealed by ultra-performance liquid chromatography-tandem mass spectrometry and principal component analysis.

    Science.gov (United States)

    Chen, Jing; He, Zhiyong; Qin, Fang; Chen, Jie; Cao, Dongsheng; Guo, Fengxian; Zeng, Maomao

    2017-11-15

    The effects of various levels of chili pepper, Sichuan pepper, and black pepper on the amounts of 17 heterocyclic amines (HAs) from seven categories of both free and protein-bound states in roast beef patties were assessed by ultra-performance liquid chromatography-tandem mass spectrometry combined with principal component analysis. Three groups of HA, including imidazopyridines (DMIP), imidazoquinoxalines (MeIQx and 4,8-MeIQx), and β-carbolines (norharman and harman), were detected and quantified in both their free and protein-bound states, whereas PhIP was detected only in its free state, and imidazoquinolines (IQ, IQ[4,5-b], and MeIQ), α-carbolines (AαC and MeAαC), and phenylpyridines (Phe-P-1) were detected only in their protein-bound states. The results demonstrate that the peppers at all three levels had significant inhibitory effects on free PhIP, DMIP, MeIQx, and 4,8-DiMeIQx and could promote free norharman. Harman was significantly suppressed by chili pepper and black pepper, but enhanced by Sichuan pepper. All 11 protein-bound HAs, with the exception of IQ, IQ[4,5-b], and MeIQx with added chili pepper, were significantly reduced by the three peppers. The total amounts of the free and protein-bound states of all 11 HAs (1692.4 ± 78.9 ng g -1 ), imidazopyridines (5.5 ± 0.2 ng g -1 ), imidazoquinolines (7.2 ± 0.2 ng g -1 ), imidazoquinoxalines (6.9 ± 0.2 ng g -1 ), α-carbolines (20.1 ± 0.4 ng g -1 ), and β-carbolines (1651.7 ± 79.5 ng g -1 ) were suppressed by each level of all of the three peppers except for 0.5% and 1.0% chili pepper. Our findings may facilitate the inhibition of HA formation in the processing of meat products.

  10. Virial Expansion Bounds

    Science.gov (United States)

    Tate, Stephen James

    2013-10-01

    In the 1960s, the technique of using cluster expansion bounds in order to achieve bounds on the virial expansion was developed by Lebowitz and Penrose (J. Math. Phys. 5:841, 1964) and Ruelle (Statistical Mechanics: Rigorous Results. Benjamin, Elmsford, 1969). This technique is generalised to more recent cluster expansion bounds by Poghosyan and Ueltschi (J. Math. Phys. 50:053509, 2009), which are related to the work of Procacci (J. Stat. Phys. 129:171, 2007) and the tree-graph identity, detailed by Brydges (Phénomènes Critiques, Systèmes Aléatoires, Théories de Jauge. Les Houches 1984, pp. 129-183, 1986). The bounds achieved by Lebowitz and Penrose can also be sharpened by doing the actual optimisation and achieving expressions in terms of the Lambert W-function. The different bound from the cluster expansion shows some improvements for bounds on the convergence of the virial expansion in the case of positive potentials, which are allowed to have a hard core.

  11. Bound and rebound states

    International Nuclear Information System (INIS)

    Orzalesi, C.A.

    1979-01-01

    In relativistic quantum theory, bound states generate forces in the crossed channel; such forces can affect the binding and self-consistent solutions should be sought for the bound-state problem. The author investigates how self-consistency can be achieved by successive approximations, in a simple scalar model and with successive relativistic eikonal approximations (EAs). Within the generalized ladder approximation, some exact properties of the resulting ''first generation'' bound states are discussed. The binding energies in this approximation are rather small even for rather large values of the primary coupling constant. The coupling of the constituent particles to the first-generation reggeon is determined by a suitable EA and a new generalized ladder amplitude is constructed with rungs given either by the primary gluons or by the first-generation reggeons. The resulting new (second-generation) bound states are found in a reggeized EA. The size of the corrections to the binding energies due to the rebinding effects is surprisingly large. The procedure is then iterated, so as to find - again in an EA - the third-generation bound states. The procedure is found to be self-consistent already at this stage: the third-generation bound states coincide with those of second generation, and no further rebinding takes place in the higher iterations of the approximation method. Features - good and bad - of the model are discussed, as well as the possible relevance of rebinding mechanisms in hadron dynamics. (author)

  12. Materials Design via Optimized Intramolecular Noncovalent Interactions for High-Performance Organic Semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Xiaojie; Liao, Qiaogan; Manley, Eric F.; Wu, Zishan; Wang, Yulun; Wang, Weida; Yang, Tingbin; Shin, Young-Eun; Cheng, Xing; Liang, Yongye; Chen, Lin X.; Baeg, Kang-Jun; Marks, Tobin J.; Guo, Xugang

    2016-03-15

    We report the design, synthesis, and implemention in semiconducting polymers of a novel head-to-head linkage containing the TRTOR (3-alkyl-3'-alkoxy-2,2'-bithiophene) donor subunit having a single strategically optimized, planarizing noncovalent S···O interaction. Diverse complementary thermal, optical, electrochemical, X-ray scattering, electrical, photovoltaic, and electron microscopic characterization techniques are applied to establish structure-property correlations in a TRTOR-based polymer series. In comparison to monomers having double S···O interactions, replacing one alkoxy substituent with a less electron-donating alkyl one yields TRTOR-based polymers with significantly depressed (0.2-0.3 eV) HOMOs. Furthermore, the weaker single S···O interaction and greater TRTOR steric encumberance enhances materials processability without sacrificing backbone planarity. From another perspective, TRTOR has comparable electronic properties to ring-fused 5Hdithieno[ 3,2-b:2',3'-d]pyran (DTP) subunits, but a centrosymmetric geometry which promotes a more compact and ordered structure than bulkier, axisymmetric DTP. Compared to monosubstituted TTOR (3-alkoxy-2,2'-bithiophene), alkylation at the TRTOR bithiophene 3-position enhances conjugation and polymer crystallinity with contracted π-π stacking. Grazing incidence wide-angle X-ray scattering (GIWAXS) data reveal that the greater steric hindrance and the weaker single S···O interaction are not detrimental to close packing and high crystallinity. As a proof of materials design, copolymerizing TRTOR with phthalimides yields copolymers with promising thin-film transistor mobility as high as 0.42 cm2/(V·s) and 6.3% power conversion efficiency in polymer solar cells, the highest of any phthalimide copolymers reported to date. The depressed TRTOR HOMOs imbue these polymers with substantially increased Ion/Ioff ratios and Voc’s versus analogous subunits with multiple electron donating

  13. Materials Design via Optimized Intramolecular Noncovalent Interactions for High-Performance Organic Semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Xiaojie [Shenzhen Key Laboratory; Liao, Qiaogan [Shenzhen Key Laboratory; Manley, Eric F. [Department; Chemical; Wu, Zishan [Shenzhen Key Laboratory; Wang, Yulun [Shenzhen Key Laboratory; Wang, Weida [Shenzhen Key Laboratory; Yang, Tingbin [Shenzhen Key Laboratory; Shin, Young-Eun [Department; Cheng, Xing [Shenzhen Key Laboratory; Liang, Yongye [Shenzhen Key Laboratory; Chen, Lin X. [Department; Chemical; Baeg, Kang-Jun [Department; Marks, Tobin J. [Department; Guo, Xugang [Shenzhen Key Laboratory

    2016-03-15

    We report the design, synthesis, and implemention in semiconducting polymers of a novel head-to-head linkage containing the TRTOR (3-alkyl-3'-alkoxy-2,2'-bithiophene) donor subunit having a single strategically optimized, planarizing noncovalent S···O interaction. Diverse complementary thermal, optical, electrochemical, X-ray scattering, electrical, photovoltaic, and electron microscopic characterization techniques are applied to establish structure–property correlations in a TRTOR-based polymer series. In comparison to monomers having double S···O interactions, replacing one alkoxy substituent with a less electron-donating alkyl one yields TRTOR-based polymers with significantly depressed (0.2–0.3 eV) HOMOs. Furthermore, the weaker single S···O interaction and greater TRTOR steric encumberance enhances materials processability without sacrificing backbone planarity. From another perspective, TRTOR has comparable electronic properties to ring-fused 5H-dithieno[3,2-b:2',3'-d]pyran (DTP) subunits, but a centrosymmetric geometry which promotes a more compact and ordered structure than bulkier, axisymmetric DTP. Compared to monosubstituted TTOR (3-alkoxy-2,2'-bithiophene), alkylation at the TRTOR bithiophene 3-position enhances conjugation and polymer crystallinity with contracted π–π stacking. Grazing incidence wide-angle X-ray scattering (GIWAXS) data reveal that the greater steric hindrance and the weaker single S···O interaction are not detrimental to close packing and high crystallinity. As a proof of materials design, copolymerizing TRTOR with phthalimides yields copolymers with promising thin-film transistor mobility as high as 0.42 cm2/(V·s) and 6.3% power conversion efficiency in polymer solar cells, the highest of any phthalimide copolymers reported to date. The depressed TRTOR HOMOs imbue these polymers with substantially increased Ion/Ioff ratios and Voc’s versus analogous subunits with multiple electron

  14. Noncovalent Intermolecular Interactions in Organic Electronic Materials: Implications for the Molecular Packing vs Electronic Properties of Acenes

    KAUST Repository

    Sutton, Christopher; Risko, Chad; Bredas, Jean-Luc

    2015-01-01

    Noncovalent intermolecular interactions, which can be tuned through the toolbox of synthetic chemistry, determine not only the molecular packing but also the resulting electronic, optical, and mechanical properties of materials derived from π

  15. Second-Generation Non-Covalent NAAA Inhibitors are Protective in a Model of Multiple Sclerosis.

    Science.gov (United States)

    Migliore, Marco; Pontis, Silvia; Fuentes de Arriba, Angel Luis; Realini, Natalia; Torrente, Esther; Armirotti, Andrea; Romeo, Elisa; Di Martino, Simona; Russo, Debora; Pizzirani, Daniela; Summa, Maria; Lanfranco, Massimiliano; Ottonello, Giuliana; Busquet, Perrine; Jung, Kwang-Mook; Garcia-Guzman, Miguel; Heim, Roger; Scarpelli, Rita; Piomelli, Daniele

    2016-09-05

    Palmitoylethanolamide (PEA) and oleoylethanolamide (OEA) are endogenous lipid mediators that suppress inflammation. Their actions are terminated by the intracellular cysteine amidase, N-acylethanolamine acid amidase (NAAA). Even though NAAA may offer a new target for anti-inflammatory therapy, the lipid-like structures and reactive warheads of current NAAA inhibitors limit the use of these agents as oral drugs. A series of novel benzothiazole-piperazine derivatives that inhibit NAAA in a potent and selective manner by a non-covalent mechanism are described. A prototype member of this class (8) displays high oral bioavailability, access to the central nervous system (CNS), and strong activity in a mouse model of multiple sclerosis (MS). This compound exemplifies a second generation of non-covalent NAAA inhibitors that may be useful in the treatment of MS and other chronic CNS disorders. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. PyContact: Rapid, Customizable, and Visual Analysis of Noncovalent Interactions in MD Simulations.

    Science.gov (United States)

    Scheurer, Maximilian; Rodenkirch, Peter; Siggel, Marc; Bernardi, Rafael C; Schulten, Klaus; Tajkhorshid, Emad; Rudack, Till

    2018-02-06

    Molecular dynamics (MD) simulations have become ubiquitous in all areas of life sciences. The size and model complexity of MD simulations are rapidly growing along with increasing computing power and improved algorithms. This growth has led to the production of a large amount of simulation data that need to be filtered for relevant information to address specific biomedical and biochemical questions. One of the most relevant molecular properties that can be investigated by all-atom MD simulations is the time-dependent evolution of the complex noncovalent interaction networks governing such fundamental aspects as molecular recognition, binding strength, and mechanical and structural stability. Extracting, evaluating, and visualizing noncovalent interactions is a key task in the daily work of structural biologists. We have developed PyContact, an easy-to-use, highly flexible, and intuitive graphical user interface-based application, designed to provide a toolkit to investigate biomolecular interactions in MD trajectories. PyContact is designed to facilitate this task by enabling identification of relevant noncovalent interactions in a comprehensible manner. The implementation of PyContact as a standalone application enables rapid analysis and data visualization without any additional programming requirements, and also preserves full in-program customization and extension capabilities for advanced users. The statistical analysis representation is interactively combined with full mapping of the results on the molecular system through the synergistic connection between PyContact and VMD. We showcase the capabilities and scientific significance of PyContact by analyzing and visualizing in great detail the noncovalent interactions underlying the ion permeation pathway of the human P2X 3 receptor. As a second application, we examine the protein-protein interaction network of the mechanically ultrastable cohesin-dockering complex. Copyright © 2017 Biophysical Society

  17. Small-angle X-ray scattering analysis reveals the ATP-bound monomeric state of the ATPase domain from the homodimeric MutL endonuclease, a GHKL phosphotransferase superfamily protein.

    Science.gov (United States)

    Iino, Hitoshi; Hikima, Takaaki; Nishida, Yuya; Yamamoto, Masaki; Kuramitsu, Seiki; Fukui, Kenji

    2015-05-01

    DNA mismatch repair is an excision system that removes mismatched bases chiefly generated by replication errors. In this system, MutL endonucleases direct the excision reaction to the error-containing strand of the duplex by specifically incising the newly synthesized strand. Both bacterial homodimeric and eukaryotic heterodimeric MutL proteins belong to the GHKL ATPase/kinase superfamily that comprises the N-terminal ATPase and C-terminal dimerization regions. Generally, the GHKL proteins show large ATPase cycle-dependent conformational changes, including dimerization-coupled ATP binding of the N-terminal domain. Interestingly, the ATPase domain of human PMS2, a subunit of the MutL heterodimer, binds ATP without dimerization. The monomeric ATP-bound state of the domain has been thought to be characteristic of heterodimeric GHKL proteins. In this study, we characterized the ATP-bound state of the ATPase domain from the Aquifex aeolicus MutL endonuclease, which is a homodimeric GHKL protein unlike the eukaryotic MutL. Gel filtration, dynamic light scattering, and small-angle X-ray scattering analyses clearly showed that the domain binds ATP in a monomeric form despite its homodimeric nature. This indicates that the uncoupling of dimerization and ATP binding is a common feature among bacterial and eukaryotic MutL endonucleases, which we suggest is closely related to the molecular mechanisms underlying mismatch repair.

  18. Alignment of non-covalent interactions at protein-protein interfaces.

    Directory of Open Access Journals (Sweden)

    Hongbo Zhu

    Full Text Available BACKGROUND: The study and comparison of protein-protein interfaces is essential for the understanding of the mechanisms of interaction between proteins. While there are many methods for comparing protein structures and protein binding sites, so far no methods have been reported for comparing the geometry of non-covalent interactions occurring at protein-protein interfaces. METHODOLOGY/PRINCIPAL FINDINGS: Here we present a method for aligning non-covalent interactions between different protein-protein interfaces. The method aligns the vector representations of van der Waals interactions and hydrogen bonds based on their geometry. The method has been applied to a dataset which comprises a variety of protein-protein interfaces. The alignments are consistent to a large extent with the results obtained using two other complementary approaches. In addition, we apply the method to three examples of protein mimicry. The method successfully aligns respective interfaces and allows for recognizing conserved interface regions. CONCLUSIONS/SIGNIFICANCE: The Galinter method has been validated in the comparison of interfaces in which homologous subunits are involved, including cases of mimicry. The method is also applicable to comparing interfaces involving non-peptidic compounds. Galinter assists users in identifying local interface regions with similar patterns of non-covalent interactions. This is particularly relevant to the investigation of the molecular basis of interaction mimicry.

  19. Geometric Shape Regulation and Noncovalent Synthesis of One-Dimensional Organic Luminescent Nano-/Micro-Materials.

    Science.gov (United States)

    Song, Xiaoxian; Zhang, Zuolun; Zhang, Shoufeng; Wei, Jinbei; Ye, Kaiqi; Liu, Yu; Marder, Todd B; Wang, Yue

    2017-08-03

    Noncovalent synthesis of one-dimensional (1D) organic nano-/micro-materials with controllable geometric shapes or morphologies and special luminescent and electronic properties is one of the greatest challenges in modern chemistry and material science. Control of noncovalent interactions is fundamental for realizing desired 1D structures and crucial for understanding the functions of these interactions. Here, a series of thiophene-fused phenazines composed of a halogen-substituted π-conjugated plate and a pair of flexible side chains is presented, which displays halogen-dependent 1D self-assemblies. Luminescent 1D twisted wires, straight rods, and zigzag wires, respectively, can be generated in sequence when the halogen atoms are varied from the lightest F to the heaviest I. It was demonstrated that halogen-dependent anisotropic noncovalent interactions and mirror-symmetrical crystallization dominated the 1D-assembly behaviors of this class of molecules. The methodology developed in this study provides a potential strategy for constructing 1D organic materials with unique optoelectronic functions.

  20. Non-covalent interaction between polyubiquitin and GTP cyclohydrolase 1 dictates its degradation.

    Directory of Open Access Journals (Sweden)

    Yu Zhao

    Full Text Available GTP cyclohydrolase 1 (GTPCH1 is the rate-limiting enzyme in the de novo synthesis of tetrahydrobiopterin (BH4. GTPCH1 protein degradation has been reported in animal models of several diseases, including diabetes mellitus and hypertension. However, the molecular mechanisms by which GTPCH1 is degraded remain uncharacterized. Here we report a novel non-covalent interaction between polyubiquitin and GTPCH1 in vitro and in vivo. The non-covalent binding of GTPCH1 to polyubiquitin via an ubiquitin-binding domain (UBD results in ubiquitination and degradation. Ectopic expression of ubiquitin in cultured cells accelerated GTPCH1 degradation. In cultured cells and in vitro assays, Lys48-linked ubiquitin chains, but not Lys63-linked chains, interacted with GTPCH1 and targeted it for degradation. Consistently, proteasome inhibition attenuated GTPCH1 degradation. Finally, direct mutagenesis of an isoleucine (Ile131 in the hydrophobic patch of the GTPCH1 UBD affected its ubiquitin binding and the enzyme stability. Taken together, we conclude that GTPCH1 non-covalently interacts with polyubiquitin via an ubiquitin-binding domain. The polyubiquitin binding directs GTPCH1 ubiquitination and proteasome degradation.

  1. Bounded Tamper Resilience

    DEFF Research Database (Denmark)

    Damgård, Ivan Bjerre; Faust, Sebastian; Mukherjee, Pratyay

    2013-01-01

    Related key attacks (RKAs) are powerful cryptanalytic attacks where an adversary can change the secret key and observe the effect of such changes at the output. The state of the art in RKA security protects against an a-priori unbounded number of certain algebraic induced key relations, e.......g., affine functions or polynomials of bounded degree. In this work, we show that it is possible to go beyond the algebraic barrier and achieve security against arbitrary key relations, by restricting the number of tampering queries the adversary is allowed to ask for. The latter restriction is necessary......-protocols (including the Okamoto scheme, for instance) are secure even if the adversary can arbitrarily tamper with the prover’s state a bounded number of times and obtain some bounded amount of leakage. Interestingly, for the Okamoto scheme we can allow also independent tampering with the public parameters. We show...

  2. Massive Galileon positivity bounds

    Science.gov (United States)

    de Rham, Claudia; Melville, Scott; Tolley, Andrew J.; Zhou, Shuang-Yong

    2017-09-01

    The EFT coefficients in any gapped, scalar, Lorentz invariant field theory must satisfy positivity requirements if there is to exist a local, analytic Wilsonian UV completion. We apply these bounds to the tree level scattering amplitudes for a massive Galileon. The addition of a mass term, which does not spoil the non-renormalization theorem of the Galileon and preserves the Galileon symmetry at loop level, is necessary to satisfy the lowest order positivity bound. We further show that a careful choice of successively higher derivative corrections are necessary to satisfy the higher order positivity bounds. There is then no obstruction to a local UV completion from considerations of tree level 2-to-2 scattering alone. To demonstrate this we give an explicit example of such a UV completion.

  3. Unexpected strong attraction in the presence of continuum bound state

    International Nuclear Information System (INIS)

    Delfino, A.; Frederico, T.

    1992-06-01

    The result of few-particle ground-state calculation employing a two-particle non-local potential supporting a continuum bound state in addition to a negative-energy bound state has occasionally revealed unexpected large attraction in producing a very strongly bound ground state. In the presence of the continuum bound state the difference of phase shift between zero and infinite energies has an extra jump of φ as in the presence of an additional bound state. The wave function of the continuum bound state is identical with that of a strongly bound negative-energy state, which leads us to postulate a pseudo bound state in the two-particle system in order to explain the unexpected attraction. The role of the Pauli forbidden states is expected to be similar to these pseudo states. (author)

  4. Patient-derived Hormone-naive Prostate Cancer Xenograft Models Reveal Growth Factor Receptor Bound Protein 10 as an Androgen Receptor-repressed Gene Driving the Development of Castration-resistant Prostate Cancer.

    Science.gov (United States)

    Hao, Jun; Ci, Xinpei; Xue, Hui; Wu, Rebecca; Dong, Xin; Choi, Stephen Yiu Chuen; He, Haiqing; Wang, Yu; Zhang, Fang; Qu, Sifeng; Zhang, Fan; Haegert, Anne M; Gout, Peter W; Zoubeidi, Amina; Collins, Colin; Gleave, Martin E; Lin, Dong; Wang, Yuzhuo

    2018-06-01

    Although androgen deprivation therapy is initially effective in controlling growth of hormone-naive prostate cancers (HNPCs) in patients, currently incurable castration-resistant prostate cancer (CRPC) inevitably develops. To identify CRPC driver genes that may provide new targets to enhance CRPC therapy. Patient-derived xenografts (PDXs) of HNPCs that develop CRPC following host castration were examined for changes in expression of genes at various time points after castration using transcriptome profiling analysis; particular attention was given to pre-CRPC changes in expression indicative of genes acting as potential CRPC drivers. The functionality of a potential CRPC driver was validated via its knockdown in cultured prostate cancer cells; its clinical relevance was established using data from prostate cancer patient databases. Eighty genes were found to be significantly upregulated at the CRPC stage, while seven of them also showed elevated expression prior to CRPC development. Among the latter, growth factor receptor bound protein 10 (GRB10) was the most significantly and consistently upregulated gene. Moreover, elevated GRB10 expression in clinical prostate cancer samples correlated with more aggressive tumor types and poorer patient treatment outcome. GRB10 knockdown markedly reduced prostate cancer cell proliferation and activity of AKT, a well-established CRPC mediator. A positive correlation between AKT activity and GRB10 expression was also found in clinical cohorts. GRB10 acts as a driver of CRPC and sensitizes androgen receptor pathway inhibitors, and hence GRB10 targeting provides a novel therapeutic strategy for the disease. Development of castration-resistant prostate cancer (CRPC) is a major problem in the management of the disease. Using state-of-the-art patient-derived hormone-naive prostate cancer xenograft models, we found and validated the growth factor receptor bound protein 10 gene as a driver of CRPC, indicating that it may be used as a

  5. Bounded variation and around

    CERN Document Server

    Appell, Jürgen; Merentes Díaz, Nelson José

    2013-01-01

    This monographis a self-contained exposition of the definition and properties of functionsof bounded variation and their various generalizations; the analytical properties of nonlinear composition operators in spaces of such functions; applications to Fourier analysis, nonlinear integral equations, and boundary value problems. The book is written for non-specialists. Every chapter closes with a list of exercises and open problems.

  6. Artificial nacre-like papers based on noncovalent functionalized boron nitride nanosheets with excellent mechanical and thermally conductive properties.

    Science.gov (United States)

    Zeng, Xiaoliang; Ye, Lei; Yu, Shuhui; Li, Hao; Sun, Rong; Xu, Jianbin; Wong, Ching-Ping

    2015-04-21

    Inspired by the nano/microscale hierarchical structure and the precise inorganic/organic interface of natural nacre, we fabricated artificial nacre-like papers based on noncovalent functionalized boron nitride nanosheets (NF-BNNSs) and poly(vinyl alcohol) (PVA) via a vacuum-assisted self-assembly technique. The artificial nacre-like papers exhibit excellent tensile strength (125.2 MPa), on a par with that of the natural nacre, and moreover display a 30% higher toughness (2.37 MJ m(-3)) than that of the natural nacre. These excellent mechanical properties result from an ordered 'brick-and-mortar' arrangement of NF-BNNSs and PVA, in which the long-chain PVA molecules act as the bridge to link NF-BNNSs via hydrogen bonds. The resulting papers also render high thermal conductivity (6.9 W m(-1) K(-1)), and reveal their superiority as flexible substrates to support light-emitting-diode chips. The combined mechanical and thermal properties make the materials highly desirable as flexible substrates for next-generation commercial portable electronics.

  7. Production of recombinant cholesterol oxidase containing covalently bound FAD in Escherichia coli

    Directory of Open Access Journals (Sweden)

    Molla Gianluca

    2010-04-01

    Full Text Available Abstract Background Cholesterol oxidase is an alcohol dehydrogenase/oxidase flavoprotein that catalyzes the dehydrogenation of C(3-OH of cholesterol. It has two major biotechnological applications, i.e. in the determination of serum (and food cholesterol levels and as biocatalyst providing valuable intermediates for industrial steroid drug production. Cholesterol oxidases of type I are those containing the FAD cofactor tightly but not covalently bound to the protein moiety, whereas type II members contain covalently bound FAD. This is the first report on the over-expression in Escherichia coli of type II cholesterol oxidase from Brevibacterium sterolicum (BCO. Results Design of the plasmid construct encoding the mature BCO, optimization of medium composition and identification of the best cultivation/induction conditions for growing and expressing the active protein in recombinant E. coli cells, concurred to achieve a valuable improvement: BCO volumetric productivity was increased from ~500 up to ~25000 U/L and its crude extract specific activity from 0.5 up to 7.0 U/mg protein. Interestingly, under optimal expression conditions, nearly 55% of the soluble recombinant BCO is produced as covalently FAD bound form, whereas the protein containing non-covalently bound FAD is preferentially accumulated in insoluble inclusion bodies. Conclusions Comparison of our results with those published on non-covalent (type I COs expressed in recombinant form (either in E. coli or Streptomyces spp., shows that the fully active type II BCO can be produced in E. coli at valuable expression levels. The improved over-production of the FAD-bound cholesterol oxidase will support its development as a novel biotool to be exploited in biotechnological applications.

  8. Conformers and non-covalent interactions studied by laser spectroscopies and ab initio calculations

    Energy Technology Data Exchange (ETDEWEB)

    Ullrich, Susanne

    2001-07-01

    The model peptides, formanilide and acetanilide, and their weakly bound complexes were studied in the gas-phase using resonance enhanced multi-photon ionisation (REMPI) and zero electron kinetic energy (ZEKE) photoelectron spectroscopy. Both, cis- and trans-isomers of formanilide, were observed under molecular beam conditions. Trans-formanilide displayed predominantly in-plane vibrational excitation indicative of a planar geometry with modest geometry changes upon excitation and ionisation. In cis-formanilide the side-chain is twisted compared to the phenyl plane in the S{sub 0} state, but planar in the S{sub 1} and D{sub 0} states, revealed in characteristic side-chain torsional and out-of-plane bending excitations. Additionally, the ZEKE spectra provide evidence that excess cationic charge is delocalised from the aromatic ring to the side chain. The work on trans-formanilide was extended to its van der Waals complex with Argon with the purpose of investigating the torsional potential of the side-chain and probing charge delocalisation. Complexation of amides with water is of considerable interest since water is not only present as a bulk solvent surrounding a peptide but also attached to specific binding sites in its interior. Evidence was found for the existence of a NH- and CO-bound isomer of trans-formanilide in the neutral, S{sub 0} and S{sub 1}, states, with the ZEKE spectrum of the cationic 'CO-bound' complex indicating a strong preference for the NH binding site. (author)

  9. Maps of Bounded Rationality

    OpenAIRE

    Kahneman, Daniel

    2002-01-01

    The work cited by the Nobel committee was done jointly with the late Amos Tversky (1937-1996) during a long and unusually close collaboration. Together, we explored the psychology of intuitive beliefs and choices and examined their bounded rationality. This essay presents a current perspective on the three major topics of our joint work: heuristics of judgment, risky choice, and framing effects. In all three domains we studied intuitions - thoughts and preferences that come to mind quickly an...

  10. Bounded Satisfiability for PCTL

    OpenAIRE

    Bertrand, Nathalie; Fearnley, John; Schewe, Sven

    2012-01-01

    While model checking PCTL for Markov chains is decidable in polynomial-time, the decidability of PCTL satisfiability, as well as its finite model property, are long standing open problems. While general satisfiability is an intriguing challenge from a purely theoretical point of view, we argue that general solutions would not be of interest to practitioners: such solutions could be too big to be implementable or even infinite. Inspired by bounded synthesis techniques, we turn to the more appl...

  11. Noncovalently-functionalized reduced graphene oxide sheets by water-soluble methyl green for supercapacitor application

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Xiaoying; Hu, Zhongai, E-mail: zhongai@nwnu.edu.cn; Hu, Haixiong; Qiang, Ruibin; Li, Li; Li, Zhimin; Yang, Yuying; Zhang, Ziyu; Wu, Hongying

    2015-10-15

    Graphical abstract: Electroactive methyl green (MG) is selected to functionalize reduced graphene oxide (RGO) through non-covalent modification and the composite achieves high specific capacitance, good rate capability and excellent long life cycle. - Highlights: • MG–RGO composites were firstly prepared through non-covalent modification. • The mass ratio in composites is a key for achieving high specific capacitance. • MG–RGO 5:4 exhibits the highest specific capacitance of 341 F g{sup −1}. • MG–RGO 5:4 shows excellent rate capability and long life cycle. - Abstract: In the present work, water-soluble electroactive methyl green (MG) has been used to non-covalently functionalize reduced graphene oxide (RGO) for enhancing supercapacitive performance. The microstructure, composition and morphology of MG–RGO composites are systematically characterized by UV–vis absorption, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The electrochemical performances are investigated by cyclic voltammetry (CV), galvanostatic charge/discharge and electrochemical impedance spectroscopy (EIS). The fast redox reactions from MG could generate additional pseudocapacitance, which endows RGO higher capacitances. As a result, the MG–RGO composite (with the 5:4 mass ratio of MG:RGO) achieve a maximum value of 341 F g{sup −1} at 1 A g{sup −1} within the potential range from −0.25 to 0.75 V and provide a 180% enhancement in specific capacitance in comparison with pure RGO. Furthermore, excellent rate capability (72% capacitance retention from 1 A g{sup −1} to 20 A g{sup −1}) and long life cycle (12% capacitance decay after 5000 cycles) are achieved for the MG–RGO composite electrode.

  12. Correlating Nitrile IR Frequencies to Local Electrostatics Quantifies Noncovalent Interactions of Peptides and Proteins.

    Science.gov (United States)

    Deb, Pranab; Haldar, Tapas; Kashid, Somnath M; Banerjee, Subhrashis; Chakrabarty, Suman; Bagchi, Sayan

    2016-05-05

    Noncovalent interactions, in particular the hydrogen bonds and nonspecific long-range electrostatic interactions are fundamental to biomolecular functions. A molecular understanding of the local electrostatic environment, consistently for both specific (hydrogen-bonding) and nonspecific electrostatic (local polarity) interactions, is essential for a detailed understanding of these processes. Vibrational Stark Effect (VSE) has proven to be an extremely useful method to measure the local electric field using infrared spectroscopy of carbonyl and nitrile based probes. The nitrile chemical group would be an ideal choice because of its absorption in an infrared spectral window transparent to biomolecules, ease of site-specific incorporation into proteins, and common occurrence as a substituent in various drug molecules. However, the inability of VSE to describe the dependence of IR frequency on electric field for hydrogen-bonded nitriles to date has severely limited nitrile's utility to probe the noncovalent interactions. In this work, using infrared spectroscopy and atomistic molecular dynamics simulations, we have reported for the first time a linear correlation between nitrile frequencies and electric fields in a wide range of hydrogen-bonding environments that may bridge the existing gap between VSE and H-bonding interactions. We have demonstrated the robustness of this field-frequency correlation for both aromatic nitriles and sulfur-based nitriles in a wide range of molecules of varying size and compactness, including small molecules in complex solvation environments, an amino acid, disordered peptides, and structured proteins. This correlation, when coupled to VSE, can be used to quantify noncovalent interactions, specific or nonspecific, in a consistent manner.

  13. Noncovalent Complexation of Monoamine Neurotransmitters and Related Ammonium Ions by Tetramethoxy Tetraglucosylcalix[4]arene

    Science.gov (United States)

    Torvinen, Mika; Kalenius, Elina; Sansone, Francesco; Casnati, Alessandro; Jänis, Janne

    2012-02-01

    The noncovalent complexation of monoamine neurotransmitters and related ammonium and quaternary ammonium ions by a conformationally flexible tetramethoxy glucosylcalix[4]arene was studied by electrospray ionization Fourier transform ion cyclotron resonance (ESI-FTICR) mass spectrometry. The glucosylcalixarene exhibited highest binding affinity towards serotonin, norepinephrine, epinephrine, and dopamine. Structural properties of the guests, such as the number, location, and type of hydrogen bonding groups, length of the alkyl spacer between the ammonium head-group and the aromatic ring structure, and the degree of nitrogen substitution affected the complexation. Competition experiments and guest-exchange reactions indicated that the hydroxyl groups of guests participate in intermolecular hydrogen bonding with the glucocalixarene.

  14. Synthesis and non-covalent functionalization of carbon nanotubes rings: new nanomaterials with lectin affinity

    International Nuclear Information System (INIS)

    Assali, Mohyeddin; Leal, Manuel Pernía; Khiar, Noureddine; Fernández, Inmaculada

    2013-01-01

    We present a mild and practical carbon nanotubes rings (CNRs) synthesis from non-covalent functionalized and water-soluble linear single-wall carbon nanotubes. The hemi-micellar–supramolecular self-organization of lactose-based glycolipid 1 on the ring surface, followed by photo-polymerization of the diacetylenic function triggered by UV light afforded the first water-soluble and biocompatible CNRs. The obtained donut-like nanoconstructs expose a high density of lactose moieties on their surface, and are able to engage specific interactions with Arachis hypogea lectin similar to glycoconjugates on the cell membrane. (paper)

  15. Arginine-rich intracellular delivery peptides noncovalently transport protein into living cells

    International Nuclear Information System (INIS)

    Wang, Y.-H.; Chen, C.-P.; Chan, M.-H.; Chang, M.; Hou, Y.-W.; Chen, H.-H.; Hsu, H.-R.; Liu, Kevin; Lee, H.-J.

    2006-01-01

    Plasma membranes of plant or animal cells are generally impermeable to peptides or proteins. Many basic peptides have previously been investigated and covalently cross-linked with cargoes for cellular internalization. In the current study, we demonstrate that arginine-rich intracellular delivery (AID) peptides are able to deliver fluorescent proteins or β-galactosidase enzyme into animal and plant cells, as well as animal tissue. Cellular internalization and transdermal delivery of protein could be mediated by effective and nontoxic AID peptides in a neither fusion protein nor conjugation fashion. Therefore, noncovalent AID peptides may provide a useful strategy to have active proteins function in living cells and tissues in vivo

  16. Enzyme catalysis: a new definition accounting for noncovalent substrate- and product-like states.

    Science.gov (United States)

    Purich, D L

    2001-07-01

    Biological catalysis frequently causes changes in noncovalent bonding. By building on Pauling's assertion that any long-lived, chemically distinct interaction is a chemical bond, this article redefines enzyme catalysis as the facilitated making and/or breaking of chemical bonds, not just of covalent bonds. It is also argued that nearly every ATPase or GTPase is misnamed as a hydrolase and actually belongs to a distinct class of enzymes, termed here 'energases'. By transducing covalent bond energy into mechanical work, energases mediate such fundamental processes as protein folding, self-assembly, G-protein interactions, DNA replication, chromatin remodeling and even active transport.

  17. Universal bounds on current fluctuations.

    Science.gov (United States)

    Pietzonka, Patrick; Barato, Andre C; Seifert, Udo

    2016-05-01

    For current fluctuations in nonequilibrium steady states of Markovian processes, we derive four different universal bounds valid beyond the Gaussian regime. Different variants of these bounds apply to either the entropy change or any individual current, e.g., the rate of substrate consumption in a chemical reaction or the electron current in an electronic device. The bounds vary with respect to their degree of universality and tightness. A universal parabolic bound on the generating function of an arbitrary current depends solely on the average entropy production. A second, stronger bound requires knowledge both of the thermodynamic forces that drive the system and of the topology of the network of states. These two bounds are conjectures based on extensive numerics. An exponential bound that depends only on the average entropy production and the average number of transitions per time is rigorously proved. This bound has no obvious relation to the parabolic bound but it is typically tighter further away from equilibrium. An asymptotic bound that depends on the specific transition rates and becomes tight for large fluctuations is also derived. This bound allows for the prediction of the asymptotic growth of the generating function. Even though our results are restricted to networks with a finite number of states, we show that the parabolic bound is also valid for three paradigmatic examples of driven diffusive systems for which the generating function can be calculated using the additivity principle. Our bounds provide a general class of constraints for nonequilibrium systems.

  18. A bound on chaos

    Energy Technology Data Exchange (ETDEWEB)

    Maldacena, Juan [School of Natural Sciences, Institute for Advanced Study,1 Einstein Drive, Princeton, NJ (United States); Shenker, Stephen H. [Stanford Institute for Theoretical Physics and Department of Physics, Stanford University,382 Via Pueblo Mall, Stanford, CA (United States); Stanford, Douglas [School of Natural Sciences, Institute for Advanced Study,1 Einstein Drive, Princeton, NJ (United States)

    2016-08-17

    We conjecture a sharp bound on the rate of growth of chaos in thermal quantum systems with a large number of degrees of freedom. Chaos can be diagnosed using an out-of-time-order correlation function closely related to the commutator of operators separated in time. We conjecture that the influence of chaos on this correlator can develop no faster than exponentially, with Lyapunov exponent λ{sub L}≤2πk{sub B}T/ℏ. We give a precise mathematical argument, based on plausible physical assumptions, establishing this conjecture.

  19. ESI-MS study on non-covalent bond complex of rhFKBP12 and new neurogrowth promoter

    Institute of Scientific and Technical Information of China (English)

    WANG; Hongxia; (王红霞); ZHANG; Xuemin; (张学敏); YANG; Songcheng; (杨松成); XIAO; Junhai; (肖军海); NIE; Aihua; (聂爱华); ZHAO; Liqin; (赵丽琴); LI; Song; (李松)

    2003-01-01

    An ESI-MS method for studying the non-covalent bond complex of rhFKBP12 with its nonimmunosuppressive ligands was developed. The method was used to screen out three compounds capable of binding to rhFKBP12 non-covalently from 52 compounds. By competing binding experiment, the binding site and the relative binding strength of these three compounds 000107, 000308 and A2B12 with rhFKBP12 were measured. All of them have the same binding site as FK506 does. X-ray crystalline diffraction experiment of non-covalent bond complex of 000107, 000308 with rhFKBP12 by Tsinghua University showed the same results. Among them 000308 has good effect on stimulating neurite to grow in chicken sensory neuronal cultures.

  20. Noncovalent Intermolecular Interactions in Organic Electronic Materials: Implications for the Molecular Packing vs Electronic Properties of Acenes

    KAUST Repository

    Sutton, Christopher

    2015-10-30

    Noncovalent intermolecular interactions, which can be tuned through the toolbox of synthetic chemistry, determine not only the molecular packing but also the resulting electronic, optical, and mechanical properties of materials derived from π-conjugated molecules, oligomers, and polymers. Here, we provide an overview of the theoretical underpinnings of noncovalent intermolecular interactions and briefly discuss the computational chemistry approaches used to understand the magnitude of these interactions. These methodologies are then exploited to illustrate how noncovalent intermolecular interactions impact important electronic properties-such as the electronic coupling between adjacent molecules, a key parameter for charge-carrier transport-through a comparison between the prototype organic semiconductor pentacene with a series of N-substituted heteropentacenes. Incorporating an understanding of these interactions into the design of organic semiconductors can assist in developing novel materials systems from this fascinating molecular class. © 2015 American Chemical Society.

  1. Noncovalent functionalization of graphene by CdS nanohybrids for electrochemical applications

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Li [Chemical Engineering Research Center, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Qi, Wei, E-mail: qiwei@tju.edu.cn [Chemical Engineering Research Center, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); State Key Laboratory of Chemical Engineering, Tianjin University, Tianjin 300072 (China); Tianjin Key Laboratory of Membrane Science and Desalination Technology, Tianjin University, Tianjin 300072 (China); Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072 (China); Su, Rongxin [Chemical Engineering Research Center, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); State Key Laboratory of Chemical Engineering, Tianjin University, Tianjin 300072 (China); Tianjin Key Laboratory of Membrane Science and Desalination Technology, Tianjin University, Tianjin 300072 (China); Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072 (China); He, Zhimin [Chemical Engineering Research Center, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); State Key Laboratory of Chemical Engineering, Tianjin University, Tianjin 300072 (China); Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072 (China)

    2014-10-01

    Graphene–CdS (GR–CdS) nanocomposites were synthesized via a noncovalent functionalization process. To retain the intrinsic electronic and mechanical properties of graphene, the pristine graphene was firstly modified with 1-aminopyrene based on a strong π–π bond between the pyrenyl groups and the carbon rings of the graphene. Then the CdS nanocrystals were uniformly grown on the amino-graphene. The GR–CdS nanocomposites were characterized by UV–vis spectroscopy and scanning electron microscopy. A glucose biosensor was then fabricated based on the as-prepared GR–CdS nanocomposite by immobilizing glucose oxidase (GOD) in a chitosan thin film on a glassy carbon electrode. Direct electron transfer between GOD and the electrode was achieved and the biosensor showed good electrocatalytic activity with glucose ranging from 0.5 to 7.5 mM and a sensitivity of 45.4 μA mM{sup −1} cm{sup −2}. This work provided a simple and nondestructive functionalization strategy to fabricate graphene-based hybrid nanomaterials and it is expected that this composite film may find more potential applications in biosensors and biocatalysis. - Highlights: • A simple noncovalent approach to synthesize graphene–CdS (GR–CdS) nanocomposites • Direct electrochemistry of glucose oxidase based on synergistic effect of GR–CdS • A sensitive glucose biosensor was fabricated based on the GR–CdS hybrids.

  2. Noncovalent functionalization of graphene by CdS nanohybrids for electrochemical applications

    International Nuclear Information System (INIS)

    Wang, Li; Qi, Wei; Su, Rongxin; He, Zhimin

    2014-01-01

    Graphene–CdS (GR–CdS) nanocomposites were synthesized via a noncovalent functionalization process. To retain the intrinsic electronic and mechanical properties of graphene, the pristine graphene was firstly modified with 1-aminopyrene based on a strong π–π bond between the pyrenyl groups and the carbon rings of the graphene. Then the CdS nanocrystals were uniformly grown on the amino-graphene. The GR–CdS nanocomposites were characterized by UV–vis spectroscopy and scanning electron microscopy. A glucose biosensor was then fabricated based on the as-prepared GR–CdS nanocomposite by immobilizing glucose oxidase (GOD) in a chitosan thin film on a glassy carbon electrode. Direct electron transfer between GOD and the electrode was achieved and the biosensor showed good electrocatalytic activity with glucose ranging from 0.5 to 7.5 mM and a sensitivity of 45.4 μA mM −1 cm −2 . This work provided a simple and nondestructive functionalization strategy to fabricate graphene-based hybrid nanomaterials and it is expected that this composite film may find more potential applications in biosensors and biocatalysis. - Highlights: • A simple noncovalent approach to synthesize graphene–CdS (GR–CdS) nanocomposites • Direct electrochemistry of glucose oxidase based on synergistic effect of GR–CdS • A sensitive glucose biosensor was fabricated based on the GR–CdS hybrids

  3. Stereodynamic tetrahydrobiisoindole “NU-BIPHEP(O”s: functionalization, rotational barriers and non-covalent interactions

    Directory of Open Access Journals (Sweden)

    Golo Storch

    2016-07-01

    Full Text Available Stereodynamic ligands offer intriguing possibilities in enantioselective catalysis. “NU-BIPHEPs” are a class of stereodynamic diphosphine ligands which are easily accessible via rhodium-catalyzed double [2 + 2 + 2] cycloadditions. This study explores the preparation of differently functionalized “NU-BIPHEP(O” compounds, the characterization of non-covalent adduct formation and the quantification of enantiomerization barriers. In order to explore the possibilities of functionalization, we studied modifications of the ligand backbone, e.g., with 3,5-dichlorobenzoyl chloride. Diastereomeric adducts with Okamoto-type cellulose derivatives and on-column deracemization were realized on the basis of non-covalent interactions. Enantioselective dynamic HPLC (DHPLC allowed for the determination of rotational barriers of ΔG‡298K = 92.2 ± 0.3 kJ mol−1 and 99.5 ± 0.1 kJ mol−1 underlining the stereodynamic properties of “NU-BIPHEPs” and “NU-BIPHEP(Os”, respectively. These results make the preparation of tailor-made functionalized stereodynamic ligands possible and give an outline for possible applications in enantioselective catalysis.

  4. Molecular Dynamics Simulation of Barnase: Contribution of Noncovalent Intramolecular Interaction to Thermostability

    Directory of Open Access Journals (Sweden)

    Zhiguo Chen

    2013-01-01

    Full Text Available Bacillus amyloliquefaciens ribonuclease Barnase (RNase Ba is a 12 kD (kilodalton small extracellular ribonuclease. It has broad application prospects in agriculture, clinical medicine, pharmaceutical, and so forth. In this work, the thermal stability of Barnase has been studied using molecular dynamics simulation at different temperatures. The present study focuses on the contribution of noncovalent intramolecular interaction to protein stability and how they affect the thermal stability of the enzyme. Profiles of root mean square deviation and root mean square fluctuation identify thermostable and thermosensitive regions of Barnase. Analyses of trajectories in terms of secondary structure content, intramolecular hydrogen bonds and salt bridge interactions indicate distinct differences in different temperature simulations. In the simulations, Four three-member salt bridge networks (Asp8-Arg110-Asp12, Arg83-Asp75-Arg87, Lys66-Asp93-Arg69, and Asp54-Lys27-Glu73 have been identified as critical salt bridges for thermostability which are maintained stably at higher temperature enhancing stability of three hydrophobic cores. The study may help enlighten our knowledge of protein structural properties, noncovalent interactions which can stabilize secondary peptide structures or promote folding, and also help understand their actions better. Such an understanding is required for designing efficient enzymes with characteristics for particular applications at desired working temperatures.

  5. Effects of multiple substitution upon the P...N noncovalent interaction

    International Nuclear Information System (INIS)

    Scheiner, Steve

    2011-01-01

    Graphical abstract: The presence of one halogen opposite the N results in strong attraction between P and N. This force is little affected by identity of Y atoms, whether H or halogen. Highlights: → Strong attractive force directly between trivalent P and N atoms. → P...N force is unlike H-bonds or halogen bonds, but stronger than both. → Multiple halogenation beyond a single atom on P slightly weakens the interaction. - Abstract: The attractive noncovalent interaction of a P atom with N is derived primarily from two sources. Charge transfer from the N lone pair into the σ * antibonding orbital of a P-X bond that is turned away from the N atom combines with attractive Coulombic forces. As in the case of H-bonding, which is parallel in some ways to P...N attraction, placement of an electron-withdrawing substituent on the P atom enhances both of these components, and strengthens the overall interaction. However, in stark contrast with H-bonding, halogenation beyond monosubstitution does not lead to any further strengthening of the P...N noncovalent bond. Indeed, di and tri-substitution lead to small reductions in the interaction energy. In all cases, the geometry which contains a P...N bond is more stable than other candidate structures, some of which contain hydrogen or halogen bonds.

  6. A noncovalent class of papain-like protease/deubiquitinase inhibitors blocks SARS virus replication

    Energy Technology Data Exchange (ETDEWEB)

    Ratia, Kiira; Pegan, Scott; Takayama, Jun; Sleeman, Katrina; Coughlin, Melissa; Baliji, Surendranath; Chaudhuri, Rima; Fu, Wentao; Prabhakar, Bellur S.; Johnson, Michael E.; Baker, Susan C.; Ghosh, Arun K.; Mesecar, Andrew D. (Loyola); (Purdue); (UIC)

    2008-10-27

    We report the discovery and optimization of a potent inhibitor against the papain-like protease (PLpro) from the coronavirus that causes severe acute respiratory syndrome (SARS-CoV). This unique protease is not only responsible for processing the viral polyprotein into its functional units but is also capable of cleaving ubiquitin and ISG15 conjugates and plays a significant role in helping SARS-CoV evade the human immune system. We screened a structurally diverse library of 50,080 compounds for inhibitors of PLpro and discovered a noncovalent lead inhibitor with an IC{sub 50} value of 20 {mu}M, which was improved to 600 nM via synthetic optimization. The resulting compound, GRL0617, inhibited SARS-CoV viral replication in Vero E6 cells with an EC{sub 50} of 15 {mu}M and had no associated cytotoxicity. The X-ray structure of PLpro in complex with GRL0617 indicates that the compound has a unique mode of inhibition whereby it binds within the S4-S3 subsites of the enzyme and induces a loop closure that shuts down catalysis at the active site. These findings provide proof-of-principle that PLpro is a viable target for development of antivirals directed against SARS-CoV, and that potent noncovalent cysteine protease inhibitors can be developed with specificity directed toward pathogenic deubiquitinating enzymes without inhibiting host DUBs.

  7. The effect of non-covalent functionalization on the thermal conductance of graphene/organic interfaces

    International Nuclear Information System (INIS)

    Lin Shangchao; Buehler, Markus J

    2013-01-01

    The intrinsic interfacial thermal resistance at graphene/organic interfaces, as a result of mismatches in the phonon vibrational spectra of the two materials, diminishes the overall heat transfer performance of graphene/organic nanocomposites. In this paper, we use molecular dynamics (MD) simulations to design alkyl-pyrene molecules that can non-covalently functionalize graphene surfaces in contact with a model organic phase composed of octane. The alkyl-pyrene molecules possess phonon-spectra features of both graphene and octane and, therefore, can serve as phonon-spectra linkers to bridge the vibrational mismatch at the graphene/octane interface. In support of this hypothesis, we find that the best linker candidate can enhance the out-of-plane graphene/organic interfacial thermal conductance by ∼22%, attributed to its capability to compensate the low-frequency phonon mode of graphene. We also find that the length of the alkyl chain indirectly affects the interfacial thermal conductance through different orientations of these chains because they dictate the contribution of the out-of-plane high-frequency carbon–hydrogen bond vibrations to the overall phonon transport. This study advances our understanding of the less destructive non-covalent functionalization method and design principles of suitable linker molecules to enhance the thermal performance of graphene/organic nanocomposites while retaining the intrinsic chemical, thermal, and mechanical properties of pristine graphene. (paper)

  8. On the performance of the semiempirical quantum mechanical PM6 and PM7 methods for noncovalent interactions

    Science.gov (United States)

    Hostaš, Jiří; Řezáč, Jan; Hobza, Pavel

    2013-05-01

    In this Letter, we compare the recently released semiempirical method PM7 with its predecessor, PM6 with post-SCF corrections. These corrections were introduced in order to improve the description of noncovalent interactions (dispersion, hydrogen bonds and halogen bonds) and have become an integral part of PM7. A large collection of data on noncovalent interactions, covering not only interaction energies but also conformational changes and geometries, is used as a benchmark. Among the methods tested, PM6 with the latest corrections (PM6-D3H4X) yields the best results. PM7 yields only slightly worse results but brings additional improvements in the description of other molecular properties.

  9. Using PyMOL to Explore the Effects of ph on Noncovalent Interactions between Immunoglobulin G and Protein A: A Guided-Inquiry Biochemistry Activity

    Science.gov (United States)

    Roche Allred, Zahilyn D.; Tai, Heeyoung; Bretz, Stacey Lowery; Page, Richard C.

    2017-01-01

    Students' understandings of foundational concepts such as noncovalent interactions, pH and pK[subscript a] are crucial for success in undergraduate biochemistry courses. We developed a guided-inquiry activity to aid students in making connections between noncovalent interactions and pH/pK[subscript a]. Students explore these concepts by examining…

  10. Artificial nacre-like papers based on noncovalent functionalized boron nitride nanosheets with excellent mechanical and thermally conductive properties

    Science.gov (United States)

    Zeng, Xiaoliang; Ye, Lei; Yu, Shuhui; Li, Hao; Sun, Rong; Xu, Jianbin; Wong, Ching-Ping

    2015-04-01

    Inspired by the nano/microscale hierarchical structure and the precise inorganic/organic interface of natural nacre, we fabricated artificial nacre-like papers based on noncovalent functionalized boron nitride nanosheets (NF-BNNSs) and poly(vinyl alcohol) (PVA) via a vacuum-assisted self-assembly technique. The artificial nacre-like papers exhibit excellent tensile strength (125.2 MPa), on a par with that of the natural nacre, and moreover display a 30% higher toughness (2.37 MJ m-3) than that of the natural nacre. These excellent mechanical properties result from an ordered `brick-and-mortar' arrangement of NF-BNNSs and PVA, in which the long-chain PVA molecules act as the bridge to link NF-BNNSs via hydrogen bonds. The resulting papers also render high thermal conductivity (6.9 W m-1 K-1), and reveal their superiority as flexible substrates to support light-emitting-diode chips. The combined mechanical and thermal properties make the materials highly desirable as flexible substrates for next-generation commercial portable electronics.Inspired by the nano/microscale hierarchical structure and the precise inorganic/organic interface of natural nacre, we fabricated artificial nacre-like papers based on noncovalent functionalized boron nitride nanosheets (NF-BNNSs) and poly(vinyl alcohol) (PVA) via a vacuum-assisted self-assembly technique. The artificial nacre-like papers exhibit excellent tensile strength (125.2 MPa), on a par with that of the natural nacre, and moreover display a 30% higher toughness (2.37 MJ m-3) than that of the natural nacre. These excellent mechanical properties result from an ordered `brick-and-mortar' arrangement of NF-BNNSs and PVA, in which the long-chain PVA molecules act as the bridge to link NF-BNNSs via hydrogen bonds. The resulting papers also render high thermal conductivity (6.9 W m-1 K-1), and reveal their superiority as flexible substrates to support light-emitting-diode chips. The combined mechanical and thermal properties make

  11. Relativistic bound states

    International Nuclear Information System (INIS)

    Ritchie, Burke

    2006-01-01

    The Hamiltonian for Dirac's second-order equation depends nonlinearly on the potential V and the energy E. For this reason the magnetic contribution to the Hamiltonian for s-waves, which has a short range, is attractive for a repulsive Coulomb potential (V>0) and repulsive for an attractive Coulomb potential (V 2 . Usually solutions are found in the regime E=mc 2 +ε , where except for high Z, ε 2 . Here it is shown that for V>0 the attractive magnetic term and the linear repulsive term combine to support a bound state near E=0.5mc 2 corresponding to a binding energy E b =-ε =0.5mc 2

  12. A role for non-covalent SUMO interaction motifs in Pc2/CBX4 E3 activity.

    Directory of Open Access Journals (Sweden)

    Jacqueline C Merrill

    2010-01-01

    Full Text Available Modification of proteins by the small ubiquitin like modifier (SUMO is an essential process in mammalian cells. SUMO is covalently attached to lysines in target proteins via an enzymatic cascade which consists of E1 and E2, SUMO activating and conjugating enzymes. There is also a variable requirement for non-enzymatic E3 adapter like proteins, which can increase the efficiency and specificity of the sumoylation process. In addition to covalent attachment of SUMO to target proteins, specific non-covalent SUMO interaction motifs (SIMs that are generally short hydrophobic peptide motifs have been identified.Intriguingly, consensus SIMs are present in most SUMO E3s, including the polycomb protein, Pc2/Cbx4. However, a role for SIMs in SUMO E3 activity remains to be shown. We show that Pc2 contains two functional SIMs, both of which contribute to full E3 activity in mammalian cells, and are also required for sumoylation of Pc2 itself. Pc2 forms distinct sub-nuclear foci, termed polycomb bodies, and can recruit partner proteins, such as the corepressor CtBP. We demonstrate that mutation of the SIMs in Pc2 prevents Pc2-dependent CtBP sumoylation, and decreases enrichment of SUMO1 and SUMO2 at polycomb foci. Furthermore, mutational analysis of both SUMO1 and SUMO2 reveals that the SIM-interacting residues of both SUMO isoforms are required for Pc2-mediated sumoylation and localization to polycomb foci.This work provides the first clear evidence for a role for SIMs in SUMO E3 activity.

  13. Identification and Characterization of Noncovalent Interactions That Drive Binding and Specificity in DD-Peptidases and β-Lactamases.

    Science.gov (United States)

    Hargis, Jacqueline C; Vankayala, Sai Lakshmana; White, Justin K; Woodcock, H Lee

    2014-02-11

    Bacterial resistance to standard (i.e., β-lactam-based) antibiotics has become a global pandemic. Simultaneously, research into the underlying causes of resistance has slowed substantially, although its importance is universally recognized. Key to unraveling critical details is characterization of the noncovalent interactions that govern binding and specificity (DD-peptidases, antibiotic targets, versus β-lactamases, the evolutionarily derived enzymes that play a major role in resistance) and ultimately resistance as a whole. Herein, we describe a detailed investigation that elicits new chemical insights into these underlying intermolecular interactions. Benzylpenicillin and a novel β-lactam peptidomimetic complexed to the Stremptomyces R61 peptidase are examined using an arsenal of computational techniques: MD simulations, QM/MM calculations, charge perturbation analysis, QM/MM orbital analysis, bioinformatics, flexible receptor/flexible ligand docking, and computational ADME predictions. Several key molecular level interactions are identified that not only shed light onto fundamental resistance mechanisms, but also offer explanations for observed specificity. Specifically, an extended π-π network is elucidated that suggests antibacterial resistance has evolved, in part, due to stabilizing aromatic interactions. Additionally, interactions between the protein and peptidomimetic substrate are identified and characterized. Of particular interest is a water-mediated salt bridge between Asp217 and the positively charged N-terminus of the peptidomimetic, revealing an interaction that may significantly contribute to β-lactam specificity. Finally, interaction information is used to suggest modifications to current β-lactam compounds that should both improve binding and specificity in DD-peptidases and their physiochemical properties.

  14. The crystal structures of apo and cAMP-bound GlxR from Corynebacterium glutamicum reveal structural and dynamic changes upon cAMP binding in CRP/FNR family transcription factors.

    Directory of Open Access Journals (Sweden)

    Philip D Townsend

    Full Text Available The cyclic AMP-dependent transcriptional regulator GlxR from Corynebacterium glutamicum is a member of the super-family of CRP/FNR (cyclic AMP receptor protein/fumarate and nitrate reduction regulator transcriptional regulators that play central roles in bacterial metabolic regulatory networks. In C. glutamicum, which is widely used for the industrial production of amino acids and serves as a non-pathogenic model organism for members of the Corynebacteriales including Mycobacterium tuberculosis, the GlxR homodimer controls the transcription of a large number of genes involved in carbon metabolism. GlxR therefore represents a key target for understanding the regulation and coordination of C. glutamicum metabolism. Here we investigate cylic AMP and DNA binding of GlxR from C. glutamicum and describe the crystal structures of apo GlxR determined at a resolution of 2.5 Å, and two crystal forms of holo GlxR at resolutions of 2.38 and 1.82 Å, respectively. The detailed structural analysis and comparison of GlxR with CRP reveals that the protein undergoes a distinctive conformational change upon cyclic AMP binding leading to a dimer structure more compatible to DNA-binding. As the two binding sites in the GlxR homodimer are structurally identical dynamic changes upon binding of the first ligand are responsible for the allosteric behavior. The results presented here show how dynamic and structural changes in GlxR lead to optimization of orientation and distance of its two DNA-binding helices for optimal DNA recognition.

  15. Asymmetric noncovalent synthesis of self-assembled one-dimensional stacks by a chiral supramolecular auxiliary approach

    NARCIS (Netherlands)

    George, S.J.; Tomovic, Z.; Averbeke, Van B.; Beljonne, D.; Lazzaroni, R.; Schenning, A.P.H.J.; Meijer, E.W.

    2012-01-01

    Stereoselective noncovalent synthesis of one-dimensional helical self-assembled stacks of achiral oligo(p-phenylenevinylene) ureidotriazine (AOPV3) monomers is obtained by a chiral supramolecular auxiliary approach. The racemic mixture of helical stacks of achiral AOPV3 molecules is converted into

  16. Bounding approaches to system identification

    CERN Document Server

    Norton, John; Piet-Lahanier, Hélène; Walter, Éric

    1996-01-01

    In response to the growing interest in bounding error approaches, the editors of this volume offer the first collection of papers to describe advances in techniques and applications of bounding of the parameters, or state variables, of uncertain dynamical systems. Contributors explore the application of the bounding approach as an alternative to the probabilistic analysis of such systems, relating its importance to robust control-system design.

  17. Network Formation via Anion Coordination: Crystal Structures Based on the Interplay of Non-Covalent Interactions

    Directory of Open Access Journals (Sweden)

    Matteo Savastano

    2018-03-01

    Full Text Available We describe the synthesis and the structural characterization of new H2L(CF3CO22 (1 and H2L(Ph2PO42 (2 compounds containing the diprotonated form (H2L2+ of the tetrazine-based molecule 3,6-di(pyridin-4-yl-1,2,4,5-tetrazine. X-ray diffraction (XRD analysis of single crystals of these compounds showed that H2L2+ displays similar binding properties toward both anions when salt bridge interactions are taken into account. Nevertheless, the different shapes, sizes and functionalities of trifluoroacetate and diphenyl phosphate anions define quite different organization patterns leading to the peculiar crystal lattices of 1 and 2. These three-dimensional (3D architectures are self-assembled by a variety of non-covalent forces, among which prominent roles are played by fluorine–π (in 1 and anion–π (in 2 interactions.

  18. Core/Shell Conjugated Polymer/Quantum Dot Composite Nanofibers through Orthogonal Non-Covalent Interactions

    Directory of Open Access Journals (Sweden)

    Brad W. Watson

    2016-11-01

    Full Text Available Nanostructuring organic polymers and organic/inorganic hybrid materials and controlling blend morphologies at the molecular level are the prerequisites for modern electronic devices including biological sensors, light emitting diodes, memory devices and solar cells. To achieve all-around high performance, multiple organic and inorganic entities, each designed for specific functions, are commonly incorporated into a single device. Accurate arrangement of these components is a crucial goal in order to achieve the overall synergistic effects. We describe here a facile methodology of nanostructuring conjugated polymers and inorganic quantum dots into well-ordered core/shell composite nanofibers through cooperation of several orthogonal non-covalent interactions including conjugated polymer crystallization, block copolymer self-assembly and coordination interactions. Our methods provide precise control on the spatial arrangements among the various building blocks that are otherwise incompatible with one another, and should find applications in modern organic electronic devices such as solar cells.

  19. Non-covalent functionalization of single wall carbon nanotubes and graphene by a conjugated polymer

    KAUST Repository

    Jiwuer, Jilili

    2014-07-07

    We report first-principles calculations on the binding of poly[(9,9-bis-(6-bromohexylfluorene-2,7-diyl)-co-(benzene-1,4-diyl)] to a (8,0) single wall carbon nanotube (SWCNT) and to graphene. Considering different relative orientations of the subsystems, we find for the generalized gradient approximation a non-binding state, whereas the local density approximation predicts reasonable binding energies. The results coincide after inclusion of van der Waals corrections, which demonstrates a weak interaction between the polymer and SWCNT/graphene, mostly of van der Waals type. Accordingly, the density of states shows essentially no hybridization. The physisorption mechanism explains recent experimental observations and suggests that the conjugated polymer can be used for non-covalent functionalization.

  20. Non-Covalent Microgel Particles Containing Functional Payloads: Coacervation of PEG-Based Triblocks via Microfluidics.

    Science.gov (United States)

    Wang, Cynthia X; Utech, Stefanie; Gopez, Jeffrey D; Mabesoone, Mathijs F J; Hawker, Craig J; Klinger, Daniel

    2016-07-06

    Well-defined microgel particles were prepared by combining coacervate-driven cross-linking of ionic triblock copolymers with the ability to control particle size and encapsulate functional cargos inherent in microfluidic devices. In this approach, the efficient assembly of PEO-based triblock copolymers with oppositely charged end-blocks allows for bioinspired cross-linking under mild conditions in dispersed aqueous droplets. This strategy enables the integration of charged cargos into the coacervate domains (e.g., the loading of anionic model compounds through electrostatic association with cationic end-blocks). Distinct release profiles can be realized by systematically varying the chemical nature of the payload and the microgel dimensions. This mild and noncovalent assembly method represents a promising new approach to tunable microgels as scaffolds for colloidal biomaterials in therapeutics and regenerative medicine.

  1. Photoclickable dendritic molecular glue: noncovalent-to-covalent photochemical transformation of protein hybrids.

    Science.gov (United States)

    Uchida, Noriyuki; Okuro, Kou; Niitani, Yamato; Ling, Xiao; Ariga, Takayuki; Tomishige, Michio; Aida, Takuzo

    2013-03-27

    A water-soluble dendron with a fluorescein isothiocyanate (FITC) fluorescent label and bearing nine pendant guanidinium ion (Gu(+))/benzophenone (BP) pairs at its periphery (Glue(BP)-FITC) serves as a "photoclickable molecular glue". By multivalent salt-bridge formation between Gu(+) ions and oxyanions, Glue(BP)-FITC temporarily adheres to a kinesin/microtubule hybrid. Upon subsequent exposure to UV light, this noncovalent binding is made permanent via a cross-linking reaction mediated by carbon radicals derived from the photoexcited BP units. This temporal-to-permanent transformation by light occurs quickly and efficiently in this preorganized state, allowing the movements of microtubules on a kinesin-coated glass plate to be photochemically controlled. A fundamental difference between such temporal and permanent bindings was visualized by the use of "optical tweezers".

  2. Non-covalent functionalization of single wall carbon nanotubes and graphene by a conjugated polymer

    KAUST Repository

    Jiwuer, Jilili; Abdurahman, Ayjamal; Gü lseren, Oğuz; Schwingenschlö gl, Udo

    2014-01-01

    We report first-principles calculations on the binding of poly[(9,9-bis-(6-bromohexylfluorene-2,7-diyl)-co-(benzene-1,4-diyl)] to a (8,0) single wall carbon nanotube (SWCNT) and to graphene. Considering different relative orientations of the subsystems, we find for the generalized gradient approximation a non-binding state, whereas the local density approximation predicts reasonable binding energies. The results coincide after inclusion of van der Waals corrections, which demonstrates a weak interaction between the polymer and SWCNT/graphene, mostly of van der Waals type. Accordingly, the density of states shows essentially no hybridization. The physisorption mechanism explains recent experimental observations and suggests that the conjugated polymer can be used for non-covalent functionalization.

  3. Market access through bound tariffs

    DEFF Research Database (Denmark)

    Sala, Davide; Yalcin, Erdal; Schröder, Philipp

    2010-01-01

    on the risk that exporters face in destination markets. The present paper formalizes the underlying interaction of risk, fixed export costs and firms' market entry decisions based on techniques known from the real options literature; doing so we highlight the important role of bound tariffs at the extensive...... margin of trade. We find that bound tariffs are more effective with higher risk destination markets, that a large binding overhang may still command substantial market access, and that reductions in bound tariffs generate effective market access even when bound rates are above current and longterm...

  4. Market Access through Bound Tariffs

    DEFF Research Database (Denmark)

    Sala, Davide; Schröder, Philipp J.H.; Yalcin, Erdal

    on the risk that exporters face in destination markets. The present paper formalizes the underlying interaction of risk, fixed export costs and firms' market entry decisions based on techniques known from the real options literature; doing so we highlight the important role of bound tariffs at the extensive...... margin of trade. We find that bound tariffs are more effective with higher risk destination markets, that a large binding overhang may still command substantial market access, and that reductions in bound tariffs generate effective market access even when bound rates are above current and long...

  5. Optimization of single-walled carbon nanotube solubility by noncovalent PEGylation using experimental design methods

    Directory of Open Access Journals (Sweden)

    Hadidi N

    2011-04-01

    Full Text Available Naghmeh Hadidi1, Farzad Kobarfard2, Nastaran Nafissi-Varcheh3, Reza Aboofazeli11Department of Pharmaceutics, 2Department of Pharmaceutical Chemistry, 3Department of Pharmaceutical Biotechnology, School of Pharmacy, Shaheed Beheshti University of Medical Sciences, Tehran, IranAbstract: In this study, noncovalent functionalization of single-walled carbon nanotubes (SWCNTs with phospholipid-polyethylene glycols (Pl-PEGs was performed to improve the solubility of SWCNTs in aqueous solution. Two kinds of PEG derivatives, ie, Pl-PEG 2000 and Pl-PEG 5000, were used for the PEGylation process. An experimental design technique (D-optimal design and second-order polynomial equations was applied to investigate the effect of variables on PEGylation and the solubility of SWCNTs. The type of PEG derivative was selected as a qualitative parameter, and the PEG/SWCNT weight ratio and sonication time were applied as quantitative variables for the experimental design. Optimization was performed for two responses, aqueous solubility and loading efficiency. The grafting of PEG to the carbon nanostructure was determined by thermogravimetric analysis, Raman spectroscopy, and scanning electron microscopy. Aqueous solubility and loading efficiency were determined by ultraviolet-visible spectrophotometry and measurement of free amine groups, respectively. Results showed that Pl-PEGs were grafted onto SWCNTs. Aqueous solubility of 0.84 mg/mL and loading efficiency of nearly 98% were achieved for the prepared Pl-PEG 5000-SWCNT conjugates. Evaluation of functionalized SWCNTs showed that our noncovalent functionalization protocol could considerably increase aqueous solubility, which is an essential criterion in the design of a carbon nanotube-based drug delivery system and its biodistribution.Keywords: phospholipid-PEG, D-optimal design, loading efficiency, Raman spectroscopy, scanning electron microscopy, theromogravimetric analysis, carbon nanotubes

  6. Exchange-Correlation Effects for Noncovalent Interactions in Density Functional Theory.

    Science.gov (United States)

    Otero-de-la-Roza, A; DiLabio, Gino A; Johnson, Erin R

    2016-07-12

    In this article, we develop an understanding of how errors from exchange-correlation functionals affect the modeling of noncovalent interactions in dispersion-corrected density-functional theory. Computed CCSD(T) reference binding energies for a collection of small-molecule clusters are decomposed via a molecular many-body expansion and are used to benchmark density-functional approximations, including the effect of semilocal approximation, exact-exchange admixture, and range separation. Three sources of error are identified. Repulsion error arises from the choice of semilocal functional approximation. This error affects intermolecular repulsions and is present in all n-body exchange-repulsion energies with a sign that alternates with the order n of the interaction. Delocalization error is independent of the choice of semilocal functional but does depend on the exact exchange fraction. Delocalization error misrepresents the induction energies, leading to overbinding in all induction n-body terms, and underestimates the electrostatic contribution to the 2-body energies. Deformation error affects only monomer relaxation (deformation) energies and behaves similarly to bond-dissociation energy errors. Delocalization and deformation errors affect systems with significant intermolecular orbital interactions (e.g., hydrogen- and halogen-bonded systems), whereas repulsion error is ubiquitous. Many-body errors from the underlying exchange-correlation functional greatly exceed in general the magnitude of the many-body dispersion energy term. A functional built to accurately model noncovalent interactions must contain a dispersion correction, semilocal exchange, and correlation components that minimize the repulsion error independently and must also incorporate exact exchange in such a way that delocalization error is absent.

  7. Quivers of Bound Path Algebras and Bound Path Coalgebras

    Directory of Open Access Journals (Sweden)

    Dr. Intan Muchtadi

    2010-09-01

    Full Text Available bras and coalgebras can be represented as quiver (directed graph, and from quiver we can construct algebras and coalgebras called path algebras and path coalgebras. In this paper we show that the quiver of a bound path coalgebra (resp. algebra is the dual quiver of its bound path algebra (resp. coalgebra.

  8. Noncovalent DNA Binding Drives DNA Alkylation by Leinamycin. Evidence That the Z,E-5-(Thiazol-4-yl)-penta-2,4-dienone Moiety of the Natural Product Serves As An Atypical DNA Intercalator

    Science.gov (United States)

    Fekry, Mostafa I.; Szekely, Jozsef; Dutta, Sanjay; Breydo, Leonid; Zang, Hong; Gates, Kent S.

    2012-01-01

    Molecular recognition and chemical modification of DNA are important in medicinal chemistry, toxicology, and biotechnology. Historically, natural products have revealed many interesting and unexpected mechanisms for noncovalent DNA binding and covalent DNA modification. The studies reported here characterize the molecular mechanisms underlying the efficient alkylation of duplex DNA by the Streptomyces-derived natural product leinamycin. Previous studies suggested that alkylation of duplex DNA by activated leinamycin (2) is driven by noncovalent association of the natural product with the double helix. This is striking because leinamycin does not contain a classical noncovalent DNA-binding motif such as an intercalating unit, a groove binder, or a polycation. The experiments described here provide evidence that leinamycin is an atypical DNA-intercalating agent. A competition binding assay involving daunomycin-mediated inhibition of DNA alkylation by leinamycin provided evidence that activated leinamycin binds to duplex DNA with an apparent binding constant of approximately 4.3 ± 0.4 × 103 M−1. Activated leinamycin caused duplex unwinding and hydrodynamic changes in DNA-containing solutions that are indicative of DNA intercalation. Characterization of the reaction of activated leinamycin with palindromic duplexes containing 5'-CG and 5'-GC target sites, bulge-containing duplexes, and 5-methylcytosine-containing duplexes provided evidence regarding the orientation of leinamycin with respect to target guanine residues. The data allows construction of a model for the leinamycin-DNA complex suggesting how a modest DNA-binding constant combines with proper positioning of the natural product to drive efficient alkylation of guanine residues in the major groove of duplex DNA. PMID:21954957

  9. Bounds for Asian basket options

    Science.gov (United States)

    Deelstra, Griselda; Diallo, Ibrahima; Vanmaele, Michèle

    2008-09-01

    In this paper we propose pricing bounds for European-style discrete arithmetic Asian basket options in a Black and Scholes framework. We start from methods used for basket options and Asian options. First, we use the general approach for deriving upper and lower bounds for stop-loss premia of sums of non-independent random variables as in Kaas et al. [Upper and lower bounds for sums of random variables, Insurance Math. Econom. 27 (2000) 151-168] or Dhaene et al. [The concept of comonotonicity in actuarial science and finance: theory, Insurance Math. Econom. 31(1) (2002) 3-33]. We generalize the methods in Deelstra et al. [Pricing of arithmetic basket options by conditioning, Insurance Math. Econom. 34 (2004) 55-57] and Vanmaele et al. [Bounds for the price of discrete sampled arithmetic Asian options, J. Comput. Appl. Math. 185(1) (2006) 51-90]. Afterwards we show how to derive an analytical closed-form expression for a lower bound in the non-comonotonic case. Finally, we derive upper bounds for Asian basket options by applying techniques as in Thompson [Fast narrow bounds on the value of Asian options, Working Paper, University of Cambridge, 1999] and Lord [Partially exact and bounded approximations for arithmetic Asian options, J. Comput. Finance 10 (2) (2006) 1-52]. Numerical results are included and on the basis of our numerical tests, we explain which method we recommend depending on moneyness and time-to-maturity.

  10. Product differentiation under bounded rationality

    NARCIS (Netherlands)

    Vermeulen, B.; Poutré, La J.A.; Kok, de A.G.; Pyka, A.; Handa, H.; Ishibuchi, H.; Ong, Y.-S.; Tan, K.-C.

    2015-01-01

    We study product differentiation equilibria and dynamics on the Salop circle under bounded rationality. Due to bounded rationality, firms tend to agglomerate in pairs. Upon adding a second tier of component suppliers, downstream assemblers may escape pairwise horizontal agglomeration. Moreover, we

  11. Metabolism of organically bound tritium

    International Nuclear Information System (INIS)

    Travis, C.C.

    1984-01-01

    The classic methodology for estimating dose to man from environmental tritium ignores the fact that organically bound tritium in foodstuffs may be directly assimilated in the bound compartment of tissues without previous oxidation. We propose a four-compartment model consisting of a free body water compartment, two organic compartments, and a small, rapidly metabolizing compartment. The utility of this model lies in the ability to input organically bound tritium in foodstuffs directly into the organic compartments of the model. We found that organically bound tritium in foodstuffs can increase cumulative total body dose by a factor of 1.7 to 4.5 times the free body water dose alone, depending on the bound-to-loose ratio of tritium in the diet. Model predictions are compared with empirical measurements of tritium in human urine and tissue samples, and appear to be in close agreement. 10 references, 4 figures, 3 tables

  12. Quantum engine efficiency bound beyond the second law of thermodynamics.

    Science.gov (United States)

    Niedenzu, Wolfgang; Mukherjee, Victor; Ghosh, Arnab; Kofman, Abraham G; Kurizki, Gershon

    2018-01-11

    According to the second law, the efficiency of cyclic heat engines is limited by the Carnot bound that is attained by engines that operate between two thermal baths under the reversibility condition whereby the total entropy does not increase. Quantum engines operating between a thermal and a squeezed-thermal bath have been shown to surpass this bound. Yet, their maximum efficiency cannot be determined by the reversibility condition, which may yield an unachievable efficiency bound above unity. Here we identify the fraction of the exchanged energy between a quantum system and a bath that necessarily causes an entropy change and derive an inequality for this change. This inequality reveals an efficiency bound for quantum engines energised by a non-thermal bath. This bound does not imply reversibility, unless the two baths are thermal. It cannot be solely deduced from the laws of thermodynamics.

  13. Curvature bound from gravitational catalysis

    Science.gov (United States)

    Gies, Holger; Martini, Riccardo

    2018-04-01

    We determine bounds on the curvature of local patches of spacetime from the requirement of intact long-range chiral symmetry. The bounds arise from a scale-dependent analysis of gravitational catalysis and its influence on the effective potential for the chiral order parameter, as induced by fermionic fluctuations on a curved spacetime with local hyperbolic properties. The bound is expressed in terms of the local curvature scalar measured in units of a gauge-invariant coarse-graining scale. We argue that any effective field theory of quantum gravity obeying this curvature bound is safe from chiral symmetry breaking through gravitational catalysis and thus compatible with the simultaneous existence of chiral fermions in the low-energy spectrum. With increasing number of dimensions, the curvature bound in terms of the hyperbolic scale parameter becomes stronger. Applying the curvature bound to the asymptotic safety scenario for quantum gravity in four spacetime dimensions translates into bounds on the matter content of particle physics models.

  14. Combining Alphas via Bounded Regression

    Directory of Open Access Journals (Sweden)

    Zura Kakushadze

    2015-11-01

    Full Text Available We give an explicit algorithm and source code for combining alpha streams via bounded regression. In practical applications, typically, there is insufficient history to compute a sample covariance matrix (SCM for a large number of alphas. To compute alpha allocation weights, one then resorts to (weighted regression over SCM principal components. Regression often produces alpha weights with insufficient diversification and/or skewed distribution against, e.g., turnover. This can be rectified by imposing bounds on alpha weights within the regression procedure. Bounded regression can also be applied to stock and other asset portfolio construction. We discuss illustrative examples.

  15. Improved Range Searching Lower Bounds

    DEFF Research Database (Denmark)

    Larsen, Kasper Green; Nguyen, Huy L.

    2012-01-01

    by constructing a hard input set and query set, and then invoking Chazelle and Rosenberg's [CGTA'96] general theorem on the complexity of navigation in the pointer machine. For the group model, we show that input sets and query sets that are hard for range reporting in the pointer machine (i.e. by Chazelle...... and Rosenberg's theorem), are also hard for dynamic range searching in the group model. This theorem allows us to reuse decades of research on range reporting lower bounds to immediately obtain a range of new group model lower bounds. Amongst others, this includes an improved lower bound for the fundamental...

  16. Bound states in string nets

    Science.gov (United States)

    Schulz, Marc Daniel; Dusuel, Sébastien; Vidal, Julien

    2016-11-01

    We discuss the emergence of bound states in the low-energy spectrum of the string-net Hamiltonian in the presence of a string tension. In the ladder geometry, we show that a single bound state arises either for a finite tension or in the zero-tension limit depending on the theory considered. In the latter case, we perturbatively compute the binding energy as a function of the total quantum dimension. We also address this issue in the honeycomb lattice where the number of bound states in the topological phase depends on the total quantum dimension. Finally, the internal structure of these bound states is analyzed in the zero-tension limit.

  17. On functions of bounded semivariation

    Czech Academy of Sciences Publication Activity Database

    Monteiro, Giselle Antunes

    2015-01-01

    Roč. 40, č. 2 (2015), s. 233-276 ISSN 0147-1937 Institutional support: RVO:67985840 Keywords : semivariation * functions of bounded variation * regulated functions Subject RIV: BA - General Mathematics http://projecteuclid.org/euclid.rae/1491271216

  18. Computational Lower Bounds Using Diagonalization

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 14; Issue 7. Computational Lower Bounds Using Diagonalization - Languages, Turing Machines and Complexity Classes. M V Panduranga Rao. General Article Volume 14 Issue 7 July 2009 pp 682-690 ...

  19. Observations of bound and unbound states of Ce−

    International Nuclear Information System (INIS)

    Walter, C W; Li, Y-G; Matyas, D J; Alton, R M; Lou, S E; III, R L Field; Gibson, N D; Hanstorp, D

    2012-01-01

    The negative ion of cerium has been investigated with tunable infrared laser photodetachment spectroscopy over selected photon energy ranges between 0.56 − 0.70 eV. The spectrum reveals several sharp peaks due to negative ion resonances and possible bound-bound transitions in Ce − . The newly observed transitions, together with our previous measurements, provide insight into the rich near-threshold spectrum of this lanthanide negative ion.

  20. Noncovalent interaction of polyethylene glycol with copper complex of ethylenediaminetetraacetic acid and its application in constructing inorganic nanomaterials.

    Science.gov (United States)

    Pan, Shu Zhen; Song, Le Xin; Chen, Jie; Du, Fang Yun; Yang, Jing; Xia, Juan

    2011-10-21

    In this study, we try to answer a fundamental question: what is the consequence of the noncovalent interaction between a polymer and a coordination compound? Here, polyethylene glycol (PEG-4000, PEG-b) and copper complex of ethylenediaminetetraacetic acid (H(2)CuY) were employed to solve this problem. A novel adduct (CEP) between H(2)CuY and PEG-b was prepared. Our results indicated several interesting findings. First, the introduction of H(2)CuY had no effect on the stacking structure of PEG-b but led to a large change in surface structure of the polymer. Second, there was a significant difference (117 K) in the maximum degradation temperature between the PEG and the CEP, suggesting that the noncovalent interaction can drastically improve the thermal stability of the PEG. Third, sintering experiments showed that H(2)CuY and CEP produced completely different decomposition products. The former formed Cu crystals in nitrogen and CuO in air, but the latter generated Cu and CuCl crystals with good crystallinity, respectively. Finally, three independent measurements: viscosity, conductivity and nuclear magnetic resonance in solution, provided useful information and insights from both sides of the noncovalent interaction. Probable interaction mechanisms and interaction sites were proposed. We consider that the current research could create the foundation for a new understanding of how the noncovalent adduct interaction between a metallic complex and a polymer relates to the change in physical and chemical properties of the adducted components. This journal is © The Royal Society of Chemistry 2011

  1. Preparation and Performance of Amphiphilic Random Copolymer Noncovalently Modified MWCNTs/Epoxy Composite

    Directory of Open Access Journals (Sweden)

    MA Qiang

    2016-09-01

    Full Text Available An amphiphilic random copolymer of polyglycidyl methacrylate-co-N-vinyl carbazole P(GMA-co-NVC was synthesized by free radical polymerization and was used to noncovalently modify multi-walled carbon nanotubes (MWCNTs. The obtained P(GMA-co-NVC/MWCNTs was mixed with epoxy resin and used to reinforce epoxy resin. Polymer modified carbon nanotubes/epoxy resin composites were prepared by a casting molding method. Tensile test, electrical resistivity test and differential scanning calorimeter(DSC analysis were used to study the effect of polymer modified carbon nanotubes on the mechanical, electrical, and thermal properties of epoxy resin. The results show that the epoxy composite reinforced with P(GMA-co-NVC/MWCNTs shows a remarkable enhancement in both tensile strength and elongation at break compared to either the pure epoxy or the pristine MWCNTs/epoxy composites. In addition, the electrical conductivity of epoxy is significantly improved and the volume resistivity decreases from 1014Ω·m to 106Ω·m with 0.25% mass fraction loading of P(GMA-co-NVC/MWCNTs. Moreover, glass transition temperature of the epoxy composite also increases from 144℃ to 149℃.

  2. Covalent and non-covalent chemical engineering of actin for biotechnological applications.

    Science.gov (United States)

    Kumar, Saroj; Mansson, Alf

    2017-11-15

    The cytoskeletal filaments are self-assembled protein polymers with 8-25nm diameters and up to several tens of micrometres length. They have a range of pivotal roles in eukaryotic cells, including transportation of intracellular cargoes (primarily microtubules with dynein and kinesin motors) and cell motility (primarily actin and myosin) where muscle contraction is one example. For two decades, the cytoskeletal filaments and their associated motor systems have been explored for nanotechnological applications including miniaturized sensor systems and lab-on-a-chip devices. Several developments have also revolved around possible exploitation of the filaments alone without their motor partners. Efforts to use the cytoskeletal filaments for applications often require chemical or genetic engineering of the filaments such as specific conjugation with fluorophores, antibodies, oligonucleotides or various macromolecular complexes e.g. nanoparticles. Similar conjugation methods are also instrumental for a range of fundamental biophysical studies. Here we review methods for non-covalent and covalent chemical modifications of actin filaments with focus on critical advantages and challenges of different methods as well as critical steps in the conjugation procedures. We also review potential uses of the engineered actin filaments in nanotechnological applications and in some key fundamental studies of actin and myosin function. Finally, we consider possible future lines of investigation that may be addressed by applying chemical conjugation of actin in new ways. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  3. π-Donors microstructuring on surface of polymer film by their noncovalent interactions with iodine

    Energy Technology Data Exchange (ETDEWEB)

    Traven, Valerii F., E-mail: valerii.traven@gmail.com [Mendeleev University of Chemical Technology, Moscow 125047, Miusskaya sq., 9 (Russian Federation); Ivanov, Ivan V.; Dolotov, Sergei M. [Mendeleev University of Chemical Technology, Moscow 125047, Miusskaya sq., 9 (Russian Federation); Veciana, Jaume Miro; Lebedev, Victor S. [Institut de Ciencia de Materials de Barcelona–CSIC, Campus de la UAB, 08193, Bellaterra (Spain); Shulga, Yurii M.; Khasanov, Salavat S. [Institute of Problems of Chemical Physics, Russian Academy of Sciences, Acad. N.N. Semenov Prosp., 1, Chernogolovka, 142432 (Russian Federation); Medvedev, Michael G. [A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Moscow 119991, Vavilova str., 28 (Russian Federation); Laukhina, Elena E. [The Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine, ICMAB-CSIC, Bellaterra, 08193 (Spain)

    2015-06-15

    Noncovalent (charge transfer) interaction between perylene and iodine in polycarbonate film provides formation of microstructured perylene layer on the polymer surface upon exposure of polymer film which contains dissolved perylene to solvent + iodine vapors. The prepared bilayer film possesses a sensing effect to iodine vapors which can be observed by both fluorescence and electrical conductivity changes. Similar bilayer films have been prepared also with anthracene and phenothiazine as π-donors with use of different polymer matrixes. Interaction of iodine with polycyclic aromatic hydrocarbons (PAH) has also been studied by the M06-2x DFT calculations for better understanding of phenomenon of π-donors microstructuring on surface of polymer film. - Highlights: • Preparation of bilayer polymer films with π-donors on surface for the first time. • π-Donor phase purity is confirmed by XRD, IR spectroscopy, SEM. • Perylene bilayer polymer films possess fluorescence. • Perylene bilayer polymer films loss fluorescence under iodine vapors. • Perylene bilayer polymer films possess electrical conductivity when treated by iodine vapors.

  4. An NMR study of the covalent and noncovalent interactions of CC-1065 and DNA

    International Nuclear Information System (INIS)

    Scahill, T.A.; Jensen, R.M.; Swenson, D.H.; Hatzenbuhler, N.T.; Petzold, G.; Wierenga, W.; Brahme, N.D.

    1990-01-01

    The binding of the antitumor drug CC-1065 has been studied with nuclear magnetic resonance (NMR) spectroscopy. This study involves two parts, the elucidation of the covalent binding site of the drug to DNA and a detailed investigation of the noncovalent interactions of CC-1065 with a DNA fragment through analysis of 2D NOE (NOESY) experiments. A CC-1065-DNA adduct was prepared, and an adenine adduct was released upon heating. NMR ( 1 H and 13 C) analysis of the adduct shows that the drug binds to N3 of adenine by reaction of its cyclopropyl group. The reaction pathway and product formed were determined by analysis of the 13 C DEPT spectra. An octamer duplex, d(CGATTAGC·GCTAATCG), was synthesized and used in the interaction study of CC-1065 and the oligomer. The duplex and the drug-octamer complex were both analyzed by 2D spectroscopy (COSY, NOESY). The relative intensity of the NOEs observed between the drug (CC-1065) and the octamer duplex shows conclusively that the drug is located in the minor groove, covalently attached to N3 of adenine 6 and positioned from the 3' → 5' end in relation to strand A [d(CGATTA 6 GC)]. A mechanism for drug binding and stabilization can be inferred from the NOE data and model-building studies

  5. Improving Dispersion and Barrier Properties of Polyketone/Graphene Nanoplatelet Composites via Noncovalent Functionalization Using Aminopyrene.

    Science.gov (United States)

    Cho, Jaehyun; Jeon, Ikseong; Kim, Seong Yun; Lim, Soonho; Jho, Jae Young

    2017-08-23

    A series of polyketone (PK) nanocomposite films with varying content of noncovalently functionalized graphene nanoplatelet with 1-aminopyrene (GNP/APy) is prepared by solution blending with a solvent of hexafluoro-2-propanol. GNP/APy, prepared by a facile method, can effectively induce specific interaction such as hydrogen bonding between the amine functional group of GNP/APy and the carbonyl functional group of the PK matrix. With comparison of GNP and GNP/Py as reference materials, intensive investigation on filler-matrix interaction is achieved. In addition, the dispersion state of the functionalized GNP (f-GNPs; GNP/Py and GNP/APy) in the PK matrix is analyzed by three-dimensional nondestructive X-ray microcomputed tomography, and the increased dispersion state of those fillers results in significant improvement in the water vapor transmission rate (WVTR). The enhancement in WVTR of the PK/GNP/APy nanocomposite film at 1 wt % loading of filler leads to a barrier performance approximately 2 times larger compared to that of PK/GNP nanocomposite film and an approximately 92% reduction in WVTR compared to the case of pristine PK film. We expect that this facile method of graphene functionalization to enhance graphene dispersibility as well as interfacial interaction with the polymer matrix will be widely utilized to expand the potential of graphene materials to barrier film applications.

  6. Origin of supercharging in electrospray ionization of noncovalent complexes from aqueous solution.

    Science.gov (United States)

    Sterling, Harry J; Williams, Evan R

    2009-10-01

    The use of m-nitrobenzyl alcohol (m-NBA) to enhance charging of noncovalent complexes formed by electrospray ionization from aqueous solutions was investigated. Addition of up to 1% m-NBA can result in a significant increase in the average charging of complexes, ranging from approximately 13% for the homo-heptamer of NtrC4-RC (317 kDa; maximum charge state increases from 42+ to 44+) to approximately 49% for myoglobin (17.6 kDa; maximum charge state increases from 9+ to 16+). Charge state distributions of larger complexes obtained from heated solutions to which no m-NBA was added are remarkably similar to those containing small amounts of m-NBA. Dissociation of the complexes through identical channels both upon addition of higher concentrations of m-NBA and heating is observed. These results indicate that the enhanced charging upon addition of m-NBA to aqueous electrospray solutions is a result of droplet heating owing to the high boiling point of m-NBA, which results in a change in the higher-order structure and/or dissociation of the complexes. For monomeric proteins and small complexes, the enhancement of charging is lower for heated aqueous solutions than from solutions with m-NBA because rapid folding of proteins from heated solutions that do not contain m-NBA can occur after the electrospray droplet is formed and is evaporatively cooled.

  7. Enhancing catalytic performance of Au catalysts by noncovalent functionalized graphene using functional ionic liquids

    International Nuclear Information System (INIS)

    Li, Shuwen; Guo, Shujing; Yang, Honglei; Gou, Galian; Ren, Ren; Li, Jing; Dong, Zhengping; Jin, Jun; Ma, Jiantai

    2014-01-01

    Highlights: • The new catalyst was fabricated by a facile and environment-friendly approach. • The catalyst has excellent activity and reusability due to the synergistic effect. • The approach provides a green way to synthesize low cost Au-based catalysts. - Abstract: New catalyst, prepared through Au nanoparticles anchored on the Ionic Liquid of 3,4,9,10-perylene tetracarboxylic acid-noncovalent functionalized graphene (Au/PDIL-GS), was fabricated using a facile and environment-friendly approach. The information of the morphologies, sizes, dispersion of Au nanoparticles (NPs) and chemical composition for the as-prepared catalysts was verified by systematic characterizations, including transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), Raman spectra, X-ray diffraction (XRD) and X-Ray photoelectron spectroscopy (XPS). As a new catalyst, the resulting Au/PDIL-GS exhibited excellent catalytic activity in the reduction of 4-nitrophenol because of the synergistic effect between the PDIL-GS and Au NPs. The facile and environment-friendly approach provides a green way to effectively synthesize low cost Au-based catalysts for 4-NP reduction and is promising for the development of other useful materials

  8. Stable non-covalent labeling of layered silicate nanoparticles for biological imaging.

    Science.gov (United States)

    Mortimer, Gysell M; Jack, Kevin S; Musumeci, Anthony W; Martin, Darren J; Minchin, Rodney F

    2016-04-01

    Layered silicate nanoparticles (LSN) are widely used in industrial applications and consumer products. They also have potential benefits in biomedical applications such as implantable devices and for drug delivery. To study how nanomaterials interact with cells and tissues, techniques to track and quantify their movement through different biological compartments are essential. While radiolabels can be very sensitive, particularly for in vivo studies, fluorescent labeling has been preferred in recent years because of the array of methods available to image and quantify fluorescent nanoparticles. However, labeling can be problematic, especially if it alters the physical properties of the nanomaterial. Herein is described a novel non-covalent labeling technique for LSN using readily available fluorescent dimeric cyanine dyes without the need to use excess amounts of dye to achieve labeling, or the need for removal of unbound dye. The approach utilizes the cationic binding properties of layered silicate clays and the multiple quaternary nitrogens associated with the dyes. Preparation of YOYO-1 labeled LSN with optimal dispersion in aqueous media is presented. The utilization of the labeled particles is then demonstrated in cell binding and uptake studies using flow cytometry and confocal microscopy. The labeled LSN are highly fluorescent, stable and exhibit identical physical properties with respect to the unlabeled nanoparticles. The general approach described here is applicable to other cyanine dyes and may be utilized more widely for labeling nanoparticles that comprise a crystalline plate structure with a high binding capacity. Crown Copyright © 2016. Published by Elsevier B.V. All rights reserved.

  9. Isoelectric focusing of small non-covalent metal species from plants.

    Science.gov (United States)

    Köster, Jessica; Hayen, Heiko; von Wirén, Nicolaus; Weber, Günther

    2011-03-01

    IEF is known as a powerful electrophoretic separation technique for amphoteric molecules, in particular for proteins. The objective of the present work is to prove the suitability of IEF also for the separation of small, non-covalent metal species. Investigations are performed with copper-glutathione complexes, with the synthetic ligand ethylenediamine-N,N'-bis(o-hydroxyphenyl)acetic acid (EDDHA) and respective metal complexes (Fe, Ga, Al, Ni, Zn), and with the phytosiderophore 2'-deoxymugineic acid (DMA) and its ferric complex. It is shown that ethylenediamine-N,N'-bis(o-hydroxyphenyl)acetic acid and DMA species are stable during preparative scale IEF, whereas copper-glutathione dissociates considerably. It is also shown that preparative scale IEF can be applied successfully to isolate ferric DMA from real plant samples, and that multidimensional separations are possible by combining preparative scale IEF with subsequent HPLC-MS analysis. Focusing of free ligands and respective metal complexes with di- and trivalent metals results in different pIs, but CIEF is usually needed for a reliable estimation of pI values. Limitations of the proposed methods (preparative IEF and CIEF) and consequences of the results with respect to metal speciation in plants are discussed. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Inverting Steric Effects: Using "Attractive" Noncovalent Interactions To Direct Silver-Catalyzed Nitrene Transfer.

    Science.gov (United States)

    Huang, Minxue; Yang, Tzuhsiung; Paretsky, Jonathan D; Berry, John F; Schomaker, Jennifer M

    2017-12-06

    Nitrene transfer (NT) reactions represent powerful and direct methods to convert C-H bonds into amine groups that are prevalent in many commodity chemicals and pharmaceuticals. The importance of the C-N bond has stimulated the development of numerous transition-metal complexes to effect chemo-, regio-, and diastereoselective NT. An ongoing challenge is to understand how subtle interactions between catalyst and substrate influence the site-selectivity of the C-H amination event. In this work, we explore the underlying reasons why Ag(tpa)OTf (tpa = tris(pyridylmethyl)amine) prefers to activate α-conjugated C-H bonds over 3° alkyl C(sp 3 )-H bonds and apply these insights to reaction optimization and catalyst design. Experimental results suggest possible roles of noncovalent interactions (NCIs) in directing the NT; computational studies support the involvement of π···π and Ag···π interactions between catalyst and substrate, primarily by lowering the energy of the directed transition state and reaction conformers. A simple Hess's law relationship can be employed to predict selectivities for new substrates containing competing NCIs. The insights presented herein are poised to inspire the design of other catalyst-controlled C-H functionalization reactions.

  11. Selective removal of 2,4-dichlorophenol from contaminated water using non-covalent imprinted microspheres

    International Nuclear Information System (INIS)

    Li Ying; Li Xin; Li Yuqi; Qi Jingyao; Bian Jiang; Yuan Yixing

    2009-01-01

    A molecularly imprinted polymer (MIP) for selective removal of 2,4-dichlorophenol (2,4-DCP) in water was prepared as microspheres by the reverse microemulsion polymerization method based on the non-covalent interactions between 2,4-DCP, oleic acid, and divinylbenzene in acetonitrile. Microspheres have been characterized by Fourier transform infrared spectrometer (FTIR) and energy dispersive X-ray spectrometer (EDS) studies with evidence of 2,4-DCP linkage in polymer particles and scanning electron microscopy (SEM) to study their morphological properties. The proper adsorption and selective recognition ability of the MIP were studied by an equilibrium-adsorption method. The MIP showed outstanding affinity towards 2,4-DCP in aqueous solution and the optimum pH value for binding has been found around the neutral range. The molecular recognition of 2,4-DCP was analyzed in detail by using molecular modeling software. In addition, by investigating the variation in the adsorption ability of the MIP, it clearly showed excellent reproducibility. - Molecular imprinting has potential as a remediation technology in water treatment.

  12. Noncovalently functionalized graphitic mesoporous carbon as a stable support of Pt nanoparticles for oxygen reduction

    Energy Technology Data Exchange (ETDEWEB)

    Shao, Yuyan; Zhang, Sheng; Kou, Rong; Wang, Chongmin; Viswanathan, Vilayanur; Liu, Jun; Wang, Yong; Lin, Yuehe [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Wang, Xiqing; Dai, Sheng [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

    2010-04-02

    We report a durable electrocatalyst support, highly graphitized mesoporous carbon (GMPC), for oxygen reduction in polymer electrolyte membrane (PEM) fuel cells. GMPC is prepared through graphitizing the self-assembled soft-template mesoporous carbon (MPC) under high temperature. Heat-treatment at 2800 C greatly improves the degree of graphitization while most of the mesoporous structures and the specific surface area of MPC are retained. GMPC is then noncovalently functionalized with poly(diallyldimethylammonium chloride) (PDDA) and loaded with Pt nanoparticles by reducing Pt precursor (H{sub 2}PtCl{sub 6}) in ethylene glycol. Pt nanoparticles of {proportional_to}3.0 nm in diameter are uniformly dispersed on GMPC. Compared to Pt supported on Vulcan XC-72 carbon black (Pt/XC-72), Pt/GMPC exhibits a higher mass activity towards oxygen reduction reaction (ORR) and the mass activity retention (in percentage) is improved by a factor of {proportional_to}2 after 44 h accelerated degradation test under the potential step (1.4-0.85 V) electrochemical stressing condition which focuses on support corrosion. The enhanced activity and durability of Pt/GMPC are attributed to the graphitic structure of GMPC which is more resistant to corrosion. These findings demonstrate that GMPC is a promising oxygen reduction electrocatalyst support for PEM fuel cells. The approach reported in this work provides a facile, eco-friendly promising strategy for synthesizing stable metal nanoparticles on hydrophobic support materials. (author)

  13. The non-covalent decoration of self-assembling protein fibers.

    Science.gov (United States)

    Mahmoud, Zahra N; Grundy, Daniel J; Channon, Kevin J; Woolfson, Derek N

    2010-10-01

    The design of self-assembling fibers presents challenges in basic science, and has potential for developing materials for applications in areas such as tissue engineering. A contemporary issue in the field is the construction of multi-component, functionalized systems. Previously, we have developed peptide-based fibers, the SAF system, that comprises two complementary peptides, which affords considerable control over assembly and morphology. Here we present a straightforward route to functionalizing the SAFs with small molecules and, subsequently, other moieties. This is achieved via non-covalent recruitment of charged peptide tags, which offers advantages such as further control, reversibility, and future prospects for developing recombinant tags. We demonstrate the concept by appending fluorescent labels and biotin (and thence gold nanoparticles) to the peptides, and visualising the resulting decorated SAFs by light and electron microscopy. The peptide tags bind in the nm-mum range, and show specificity compared with control peptides, and for the SAFs over similar alpha-helix-based peptide fibers. 2010 Elsevier Ltd. All rights reserved.

  14. Bioelectrochemistry of non-covalent immobilized alcohol dehydrogenase on oxidized diamond nanoparticles.

    Science.gov (United States)

    Nicolau, Eduardo; Méndez, Jessica; Fonseca, José J; Griebenow, Kai; Cabrera, Carlos R

    2012-06-01

    Diamond nanoparticles are considered a biocompatible material mainly due to their non-cytotoxicity and remarkable cellular uptake. Model proteins such as cytochrome c and lysozyme have been physically adsorbed onto diamond nanoparticles, proving it to be a suitable surface for high protein loading. Herein, we explore the non-covalent immobilization of the redox enzyme alcohol dehydrogenase (ADH) from Saccharomyces cerevisiae (E.C.1.1.1.1) onto oxidized diamond nanoparticles for bioelectrochemical applications. Diamond nanoparticles were first oxidized and physically characterized by X-ray diffraction (XRD), FT-IR and TEM. Langmuir isotherms were constructed to investigate the ADH adsorption onto the diamond nanoparticles as a function of pH. It was found that a higher packing density is achieved at the isoelectric point of the enzyme. Moreover, the relative activity of the immobilized enzyme on diamond nanoparticles was addressed under optimum pH conditions able to retain up to 70% of its initial activity. Thereafter, an ethanol bioelectrochemical cell was constructed by employing the immobilized alcohol dehydrogenase onto diamond nanoparticles, this being able to provide a current increment of 72% when compared to the blank solution. The results of this investigation suggest that this technology may be useful for the construction of alcohol biosensors or biofuel cells in the near future. Copyright © 2011 Elsevier B.V. All rights reserved.

  15. Effect of noncovalent basal plane functionalization on the quantum capacitance in graphene.

    Science.gov (United States)

    Ebrish, Mona A; Olson, Eric J; Koester, Steven J

    2014-07-09

    The concentration-dependent density of states in graphene allows the capacitance in metal-oxide-graphene structures to be tunable with the carrier concentration. This feature allows graphene to act as a variable capacitor (varactor) that can be utilized for wireless sensing applications. Surface functionalization can be used to make graphene sensitive to a particular species. In this manuscript, the effect on the quantum capacitance of noncovalent basal plane functionalization using 1-pyrenebutanoic acid succimidyl ester and glucose oxidase is reported. It is found that functionalized samples tested in air have (1) a Dirac point similar to vacuum conditions, (2) increased maximum capacitance compared to vacuum but similar to air, (3) and quantum capacitance "tuning" that is greater than that in vacuum and ambient atmosphere. These trends are attributed to reduced surface doping and random potential fluctuations as a result of the surface functionalization due to the displacement of H2O on the graphene surface and intercalation of a stable H2O layer beneath graphene that increases the overall device capacitance. The results are important for future application of graphene as a platform for wireless chemical and biological sensors.

  16. Structure of eight molecular salts assembled from noncovalent bonding between carboxylic acids, imidazole, and benzimidazole

    Science.gov (United States)

    Jin, Shouwen; Zhang, Huan; Liu, Hui; Wen, Xianhong; Li, Minghui; Wang, Daqi

    2015-09-01

    Eight organic salts of imidazole/benzimidazole have been prepared with carboxylic acids as 2-methyl-2-phenoxypropanoic acid, α-ketoglutaric acid, 5-nitrosalicylic acid, isophthalic acid, 4-nitro-phthalic acid, and 3,5-dinitrosalicylic acid. The eight crystalline forms reported are proton-transfer compounds of which the crystals and compounds were characterized by X-ray diffraction analysis, IR, mp, and elemental analysis. These structures adopted hetero supramolecular synthons, with the most common R22(7) motif observed at salts 2, 3, 5, 6 and 8. Analysis of the crystal packing of 1-8 suggests that there are extensive strong Nsbnd H⋯O, and Osbnd H⋯O hydrogen bonds (charge assisted or neutral) between acid and imidazolyl components in all of the salts. Except the classical hydrogen bonding interactions, the secondary propagating interactions also play important roles in structure extension. This variety, coupled with the varying geometries and number of acidic groups of the acids utilized, has led to the creation of eight supramolecular arrays with 1D-3D structure. The role of weak and strong noncovalent interactions in the crystal packing is analyzed. The results presented herein indicate that the strength and directionality of the Nsbnd H⋯O, and Osbnd H⋯O hydrogen bonds between acids and imidazole/benzimidazole are sufficient to bring about the formation of organic salts.

  17. A non-covalent peptide-based strategy for ex vivo and in vivo oligonucleotide delivery.

    Science.gov (United States)

    Crombez, Laurence; Morris, May C; Heitz, Frederic; Divita, Gilles

    2011-01-01

    The dramatic acceleration in identification of new nucleic acid-based therapeutic molecules such as short interfering RNA (siRNA) and peptide-nucleic acid (PNA) analogues has provided new perspectives for therapeutic targeting of specific genes responsible for pathological disorders. However, the poor cellular uptake of nucleic acids together with the low permeability of the cell membrane to negatively charged molecules remain major obstacles to their clinical development. Several non-viral strategies have been proposed to improve the delivery of synthetic short oligonucleotides both in cultured cells and in vivo. Cell-penetrating peptides constitute very promising tools for non-invasive cellular import of oligonucleotides and analogs. We recently described a non-covalent strategy based on short amphiphatic peptides (MPG8/PEP3) that have been successfully applied ex vivo and in vivo for the delivery of therapeutic siRNA and PNA molecules. PEP3 and MPG8 form stable nanoparticles with PNA analogues and siRNA, respectively, and promote their efficient cellular uptake, independently of the endosomal pathway, into a wide variety of cell lines, including primary and suspension lines, without any associated cytotoxicity. This chapter describes easy-to-handle protocols for the use of MPG-8 or PEP-3-nanoparticle technologies for PNA and siRNA delivery into adherent and suspension cell lines as well as in vivo into cancer mouse models.

  18. Simulation bounds for system availability

    International Nuclear Information System (INIS)

    Tietjen, G.L.; Waller, R.A.

    1976-01-01

    System availability is a dominant factor in the practicality of nuclear power electrical generating plants. A proposed model for obtaining either lower bounds or interval estimates on availability uses observed data on ''n'' failure-to-repair cycles of the system to estimate the parameters in the time-to-failure and time-to-repair models. These estimates are then used in simulating failure/repair cycles of the system. The availability estimate is obtained for each of 5000 samples of ''n'' failure/repair cycles to form a distribution of estimates. Specific percentile points of those simulated distributions are selected as lower simulation bounds or simulation interval bounds for the system availability. The method is illustrated with operational data from two nuclear plants for which an exponential time-to-failure and a lognormal time-to-repair are assumed

  19. Interactions between macromolecule-bound antioxidants and Trolox during liposome autoxidation

    DEFF Research Database (Denmark)

    Celik, Ecem Evrim; Amigo Rubio, Jose Manuel; Andersen, Mogens Larsen

    2017-01-01

    The interactions between free and macromolecule-bound antioxidants were investigated in order to evaluate their combined effects on the antioxidant environment. Dietary fiber (DF), protein and lipid-bound antioxidants, obtained from whole wheat, soybean and olive oil products, respectively and Tr...... of logistic function was successfully used for modelling the oxidation curve of liposomes. Principal component analysis revealed two separate phases of liposome autoxidation.......The interactions between free and macromolecule-bound antioxidants were investigated in order to evaluate their combined effects on the antioxidant environment. Dietary fiber (DF), protein and lipid-bound antioxidants, obtained from whole wheat, soybean and olive oil products, respectively...... of the simple addition effects of Trolox and bound antioxidants with measured values on lipid oxidation revealed synergetic interactions for DF and refined olive oil-bound antioxidants, and antagonistic interactions for protein and extra virgin olive oil-bound antioxidants with Trolox. A generalized version...

  20. Relativistic bound state wave functions

    International Nuclear Information System (INIS)

    Micu, L.

    2005-01-01

    A particular method of writing the bound state wave functions in relativistic form is applied to the solutions of the Dirac equation with confining potentials in order to obtain a relativistic description of a quark antiquark bound system representing a given meson. Concerning the role of the effective constituent in the present approach we first observe that without this additional constituent we couldn't expand the bound state wave function in terms of products of free states. Indeed, we notice that if the wave function depends on the relative coordinates only, all the expansion coefficients would be infinite. Secondly we remark that the effective constituent enabled us to give a Lorentz covariant meaning to the potential energy of the bound system which is now seen as the 4th component of a 4-momentum. On the other side, by relating the effective constituent to the quantum fluctuations of the background field which generate the binding, we provided a justification for the existence of some spatial degrees of freedom accompanying the interaction potential. These ones, which are quite unusual in quantum mechanics, in our model are the natural consequence of the the independence of the quarks and can be seen as the effect of the imperfect cancellation of the vector momenta during the quantum fluctuations. Related with all these we remark that the adequate representation for the relativistic description of a bound system is the momentum representation, because of the transparent and easy way of writing the conservation laws and the transformation properties of the wave functions. The only condition to be fulfilled is to find a suitable way to take into account the potential energy of the bound system. A particular feature of the present approach is that the confining forces are due to a kind of glue where both quarks are embedded. This recalls other bound state models where the wave function is factorized in terms of constituent wave functions and the confinement is

  1. Four-quark bound states

    International Nuclear Information System (INIS)

    Zouzou, S.

    1986-01-01

    In the framework of simple non-relativistic potential models, we examine the system consisting of two quarks and two antiquarks with equal or unequal masses. We search for possible bound states below the threshold for the spontaneous dissociation into two mesons. We solve the four body problem by empirical or systematic variational methods and we include the virtual meson-meson components of the wave function. With standard two-body potentials, there is no proliferation of multiquarks. With unequal quark masses, we obtain however exotic (anti Qanti Qqq) bound states with a baryonic antidiquark-quark-quark structure very analogous to the heavy flavoured (Q'qq) baryons. (orig.)

  2. Bound entanglement and local realism

    International Nuclear Information System (INIS)

    Kaszlikowski, Dagomir; Zukowski, Marek; Gnacinski, Piotr

    2002-01-01

    We show using a numerical approach, which gives necessary and sufficient conditions for the existence of local realism, that the bound entangled state presented in Bennett et al. [Phys. Rev. Lett. 82, 5385 (1999)] admits a local and realistic description. We also find the lowest possible amount of some appropriate entangled state that must be ad-mixed to the bound entangled state so that the resulting density operator has no local and realistic description and as such can be useful in quantum communication and quantum computation

  3. Functional materials based on carbon nanotubes: Carbon nanotube actuators and noncovalent carbon nanotube modification

    Science.gov (United States)

    Fifield, Leonard S.

    Carbon nanotubes have attractive inherent properties that encourage the development of new functional materials and devices based on them. The use of single wall carbon nanotubes as electromechanical actuators takes advantage of the high mechanical strength, surface area and electrical conductivity intrinsic to these molecules. The work presented here investigates the mechanisms that have been discovered for actuation of carbon nanotube paper: electrostatic, quantum chemical charge injection, pneumatic and viscoelastic. A home-built apparatus for the measurement of actuation strain is developed and utilized in the investigation. An optical fiber switch, the first demonstrated macro-scale device based on the actuation of carbon nanotubes, is described and its performance evaluated. Also presented here is a new general process designed to modify the surface of carbon nanotubes in a non-covalent, non-destructive way. This method can be used to impart new functionalities to carbon nanotube samples for a variety of applications including sensing, solar energy conversion and chemical separation. The process described involves the achievement of large degrees of graphitic surface coverage with polycyclic aromatic hydrocarbons through the use of supercritical fluids. These molecules are bifunctional agents that anchor a desired chemical group to the aromatic surface of the carbon nanotubes without adversely disrupting the conjugated backbone that gives rise the attractive electronic and physical properties of the nanotubes. Both the nanotube functionalization work and the actuator work presented here emphasize how an understanding and control of nanoscale structure and phenomena can be of vital importance in achieving desired performance for active materials. Opportunities for new devices with improved function over current state-of-the-art can be envisioned and anticipated based on this understanding and control.

  4. Strategies to balance covalent and non-covalent biomolecule attachment within collagen-GAG biomaterials.

    Science.gov (United States)

    Pence, Jacquelyn C; Gonnerman, Emily A; Bailey, Ryan C; Harley, Brendan A C

    2014-09-01

    Strategies to integrate instructive biomolecular signals into a biomaterial are becoming increasingly complex and bioinspired. While a large majority of reports still use repeated treatments with soluble factors, this approach can be prohibitively costly and difficult to translate in vivo for applications where spatial control over signal presentation is necessary. Recent efforts have explored the use of covalent immobilization of biomolecules to the biomaterial, via both bulk (ubiquitous) as well as spatially-selective light-based crosslinking, as a means to both enhance stability and bioactivity. However, little is known about how processing conditions during immobilization impact the degree of unintended non-covalent interactions, or fouling, that takes place between the biomaterial and the biomolecule of interest. Here we demonstrate the impact of processing conditions for bulk carbodiimide (EDC) and photolithography-based benzophenone (BP) crosslinking on specific attachment vs. fouling of a model protein (Concanavalin A, ConA) within collagen-glycosaminoglycan (CG) scaffolds. Collagen source significantly impacts the selectivity of biomolecule immobilization. EDC crosslinking intensity and ligand concentration significantly impacted selective immobilization. For benzophenone photoimmobilization we observed that increased UV exposure time leads to increased ConA immobilization. Immobilization efficiency for both EDC and BP strategies was maximal at physiological pH. Increasing ligand concentration during immobilization process led to enhanced immobilization for EDC chemistry, no impact on BP immobilization, but significant increases in non-specific fouling. Given recent efforts to covalently immobilize biomolecules to a biomaterial surface to enhance bioactivity, improved understanding of the impact of crosslinking conditions on selective attachment versus non-specific fouling will inform the design of instructive biomaterials for applications across tissue

  5. Noncovalently Functionalized Tungsten Disulfide Nanosheets for Enhanced Mechanical and Thermal Properties of Epoxy Nanocomposites.

    Science.gov (United States)

    Sahu, Megha; Narashimhan, Lakshmi; Prakash, Om; Raichur, Ashok M

    2017-04-26

    In the present study, noncovalently functionalized tungsten disulfide (WS 2 ) nanosheets were used as a toughening agent for epoxy nanocomposites. WS 2 was modified with branched polyethyleneimine (PEI) to increase the degree of interaction of nanosheets with the epoxy matrix and prevent restacking and agglomeration of the sheets in the epoxy matrix. The functionalization of WS 2 sheets was confirmed through Fourier transform infrared spectroscopy and thermogravimetric analysis. The exfoliation of the bulk WS 2 was confirmed through X-ray diffraction and various microscopic techniques. Epoxy nanocomposites containing up to 1 wt % of WS 2 -PEI nanosheets were fabricated. They showed a remarkable improvement in fracture toughness (K IC ). K IC increased from 0.94 to 1.72 MPa m -1/2 for WS 2 -PEI nanosheet loadings as low as 0.25 wt %. Compressive and flexural properties also showed a significant improvement as incorporation of 0.25 wt % of WS 2 -PEI nanosheets resulted in 43 and 65% increase in the compressive and flexural strengths of epoxy nanocomposites, respectively, compared with neat epoxy. Thermal stability and thermomechanical properties of the WS 2 -PEI-modified epoxy also showed a significant improvement. The simultaneous improvement in the mechanical and thermal properties could be attributed to the good dispersion of WS 2 -PEI nanosheets in the matrix, intrinsic high strength and thermal properties of the nanosheets, and improved interaction of the WS 2 nanosheets with the epoxy matrix owing to the presence of PEI molecules on the surface of the WS 2 nanosheets.

  6. Semiclassical bounds in magnetic bottles

    Czech Academy of Sciences Publication Activity Database

    Barseghyan, Diana; Exner, Pavel; Kovařík, H.; Weidl, T.

    2016-01-01

    Roč. 28, č. 1 (2016), s. 1650002 ISSN 0129-055X R&D Projects: GA ČR(CZ) GA14-06818S Institutional support: RVO:61389005 Keywords : magnetic Laplacian * discrete spectrum * eigenvalue bounds Subject RIV: BE - Theoretical Physics Impact factor: 1.426, year: 2016

  7. Positivity bounds for Sivers functions

    International Nuclear Information System (INIS)

    Kang Zhongbo; Soffer, Jacques

    2011-01-01

    We generalize a positivity constraint derived initially for parity-conserving processes to the parity-violating ones, and use it to derive non-trivial bounds on several Sivers functions, entering in the theoretical description of single spin asymmetry for various processes.

  8. Bound states of 'dressed' particles

    International Nuclear Information System (INIS)

    Shirokov, M.I.

    1994-01-01

    A new approach to the problem of bound states in relativistic quantum field theories is suggested. It uses the creation - destruction operators of 'dresses' particles which have been granted by Faddeev's (1963) 'dressing' formalism. Peculiarities of the proposed approach as compared to the known ones are discussed. 8 refs. (author)

  9. Quantum lower bound for sorting

    OpenAIRE

    Shi, Yaoyun

    2000-01-01

    We prove that \\Omega(n log(n)) comparisons are necessary for any quantum algorithm that sorts n numbers with high success probability and uses only comparisons. If no error is allowed, at least 0.110nlog_2(n) - 0.067n + O(1) comparisons must be made. The previous known lower bound is \\Omega(n).

  10. Unconditional lower bounds against advice

    NARCIS (Netherlands)

    Buhrman, H.; Fortnow, L.; Santhanam, R.

    2009-01-01

    We show several unconditional lower bounds for exponential time classes against polynomial time classes with advice, including: (1) For any constant c, NEXP not in P^{NP[n^c]} (2) For any constant c, MAEXP not in MA/n^c (3) BPEXP not in BPP/n^{o(1)}. It was previously unknown even whether NEXP in

  11. Binding energies of two deltas bound states

    International Nuclear Information System (INIS)

    Sato, Hiroshi; Saito, Koichi.

    1982-06-01

    Bound states of the two-deltas system are investigated by employing the realistic one boson exchange potential. It is found that there exist many bound states in each isospin channel and also found that the tensor interaction plays important role in producing these bound states. Relationship between these bound states and dibaryon resonances is discussed. (J.P.N.)

  12. Accuracy of the DLPNO-CCSD(T) method for non-covalent bond dissociation enthalpies from coinage metal cation complexes

    KAUST Repository

    Minenkov, Yury; Chermak, Edrisse; Cavallo, Luigi

    2015-01-01

    The performance of the domain based local pair-natural orbital coupled-cluster (DLPNO-CCSD(T)) method has been tested to reproduce the experimental gas phase ligand dissociation enthalpy in a series of Cu+, Ag+ and Au+ complexes. For 33 Cu+ - non-covalent ligand dissociation enthalpies all-electron calculations with the same method result in MUE below 2.2 kcal/mol, although a MSE of 1.4 kcal/mol indicates systematic underestimation of the experimental values. Inclusion of scalar relativistic effects for Cu either via effective core potential (ECP) or Douglass-Kroll-Hess Hamiltonian, reduces the MUE below 1.7 kcal/mol and the MSE to -1.0 kcal/mol. For 24 Ag+ - non-covalent ligand dissociation enthalpies the DLPNO-CCSD(T) method results in a mean unsigned error (MUE) below 2.1 kcal/mol and vanishing mean signed error (MSE). For 15 Au+ - non-covalent ligand dissociation enthalpies the DLPNO-CCSD(T) methods provides larger MUE and MSE, equal to 3.2 and 1.7 kcal/mol, which might be related to poor precision of the experimental measurements. Overall, for the combined dataset of 72 coinage metal ion complexes DLPNO-CCSD(T) results in a MUE below 2.2 kcal/mol and an almost vanishing MSE. As for a comparison with computationally cheaper density functional theory (DFT) methods, the routinely used M06 functional results in MUE and MSE equal to 3.6 and -1.7 kca/mol. Results converge already at CC-PVTZ quality basis set, making highly accurate DLPNO-CCSD(T) estimates to be affordable for routine calculations (single-point) on large transition metal complexes of > 100 atoms.

  13. Accuracy of the DLPNO-CCSD(T) method for non-covalent bond dissociation enthalpies from coinage metal cation complexes

    KAUST Repository

    Minenkov, Yury

    2015-08-27

    The performance of the domain based local pair-natural orbital coupled-cluster (DLPNO-CCSD(T)) method has been tested to reproduce the experimental gas phase ligand dissociation enthalpy in a series of Cu+, Ag+ and Au+ complexes. For 33 Cu+ - non-covalent ligand dissociation enthalpies all-electron calculations with the same method result in MUE below 2.2 kcal/mol, although a MSE of 1.4 kcal/mol indicates systematic underestimation of the experimental values. Inclusion of scalar relativistic effects for Cu either via effective core potential (ECP) or Douglass-Kroll-Hess Hamiltonian, reduces the MUE below 1.7 kcal/mol and the MSE to -1.0 kcal/mol. For 24 Ag+ - non-covalent ligand dissociation enthalpies the DLPNO-CCSD(T) method results in a mean unsigned error (MUE) below 2.1 kcal/mol and vanishing mean signed error (MSE). For 15 Au+ - non-covalent ligand dissociation enthalpies the DLPNO-CCSD(T) methods provides larger MUE and MSE, equal to 3.2 and 1.7 kcal/mol, which might be related to poor precision of the experimental measurements. Overall, for the combined dataset of 72 coinage metal ion complexes DLPNO-CCSD(T) results in a MUE below 2.2 kcal/mol and an almost vanishing MSE. As for a comparison with computationally cheaper density functional theory (DFT) methods, the routinely used M06 functional results in MUE and MSE equal to 3.6 and -1.7 kca/mol. Results converge already at CC-PVTZ quality basis set, making highly accurate DLPNO-CCSD(T) estimates to be affordable for routine calculations (single-point) on large transition metal complexes of > 100 atoms.

  14. A symmetric Roos bound for linear codes

    NARCIS (Netherlands)

    Duursma, I.M.; Pellikaan, G.R.

    2006-01-01

    The van Lint–Wilson AB-method yields a short proof of the Roos bound for the minimum distance of a cyclic code. We use the AB-method to obtain a different bound for the weights of a linear code. In contrast to the Roos bound, the role of the codes A and B in our bound is symmetric. We use the bound

  15. Non-covalent conjugates of single-walled carbon nanotubes and folic acid for interaction with cells overexpressing folate receptors

    DEFF Research Database (Denmark)

    Castillo, John J.; Rindzevicius, Tomas; Novoa, Leidy V.

    2013-01-01

    We here present amethod to form a noncovalent conjugate of single-walled carbon nanotubes and folic acid aimed to interact with cells over-expressing folate receptors. The bonding was obtained without covalent chemical functionalization using a simple, rapid “one pot” synthesis method. The zeta...... a low toxicity of the conjugates in the THP-1 cells. The low toxicity and the cellular uptake of single-walled carbon nanotube–folic acid by cancer cells suggest their potential use in carbon nanotube-based drug delivery systems and in the diagnosis of cancer or tropical diseases such as leishmaniasis....

  16. Inter- and intramolecular non-covalent interactions in 1-methylimidazole-2-carbaldehyde complexes of copper, silver, and gold

    Science.gov (United States)

    Koskinen, Laura; Jääskeläinen, Sirpa; Hirva, Pipsa; Haukka, Matti

    2014-09-01

    Three new imidazole compounds, [CuBr2(mimc)2] (1), [Ag(mimc)2][CF3SO3] (2), and [AuCl3(mimc)] (3) (mimc = 1-methylimidazole-2-carbaldehyde), have been synthesized, structurally characterized, and further analyzed using the QTAIM analysis. The compounds exhibit self-assembled 3D networks arising from intermolecular non-covalent interactions such as metallophilic interactions, metal-π contacts, halogens-halogen interactions, and hydrogen bonds. These weak interactions have a strong impact on the coordination sphere of the metal atoms and on the packing of compounds 1, 2, and 3.

  17. Discovery, Synthesis, And Structure-Based Optimization of a Series of N-(tert-Butyl)-2-(N-arylamido)-2-(pyridin-3-yl) Acetamides (ML188) as Potent Noncovalent Small Molecule Inhibitors of the Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV) 3CL Protease

    Energy Technology Data Exchange (ETDEWEB)

    Jacobs, Jon [Vanderbilt Univ., Nashville, TN (United States); Vanderbilt Specialized Chemistry Center for Probe Development (MLPCN), Nashville, TN (United States); Grum-Tokars, Valerie [Northwestern Univ., Chicago, IL (United States); Zhou, Ya [Vanderbilt Univ., Nashville, TN (United States); Vanderbilt Specialized Chemistry Center for Probe Development (MLPCN), Nashville, TN (United States); Turlington, Mark [Vanderbilt Univ., Nashville, TN (United States); Vanderbilt Specialized Chemistry Center for Probe Development (MLPCN), Nashville, TN (United States); Saldanha, S. Adrian [Sripps Research Inst. Molecular Screening Center, Jupiter, FL (United States); Chase, Peter [Sripps Research Inst. Molecular Screening Center, Jupiter, FL (United States); Eggler, Aimee [Purdue Univ., West Lafayette, IN (United States); Dawson, Eric S. [Vanderbilt Univ., Nashville, TN (United States); Vanderbilt Specialized Chemistry Center for Probe Development (MLPCN), Nashville, TN (United States); Baez-Santos, Yahira M. [Purdue Univ., West Lafayette, IN (United States); Tomar, Sakshi [Purdue Univ., West Lafayette, IN (United States); Mielech, Anna M. [Loyola Univ. Medical Center, Maywood, IL (United States); Baker, Susan C. [Loyola Univ. Medical Center, Maywood, IL (United States); Lindsley, Craig W. [Vanderbilt Univ., Nashville, TN (United States); Vanderbilt Specialized Chemistry Center for Probe Development (MLPCN), Nashville, TN (United States); Hodder, Peter [Sripps Research Inst. Molecular Screening Center, Jupiter, FL (United States); Mesecar, Andrew [Purdue Univ., West Lafayette, IN (United States); Stauffer, Shaun R. [Vanderbilt Univ., Nashville, TN (United States); Vanderbilt Specialized Chemistry Center for Probe Development (MLPCN), Nashville, TN (United States)

    2012-12-11

    A high-throughput screen of the NIH molecular libraries sample collection and subsequent optimization of a lead dipeptide-like series of severe acute respiratory syndrome (SARS) main protease (3CLpro) inhibitors led to the identification of probe compound ML188 (16-(R), (R)-N-(4-(tert-butyl)phenyl)-N-(2-(tert-butylamino)-2-oxo-1-(pyridin-3-yl)ethyl)furan-2-carboxamide, Pubchem CID: 46897844). But, unlike the majority of reported coronavirus 3CLpro inhibitors that act via covalent modification of the enzyme, 16-(R) is a noncovalent SARS-CoV 3CLpro inhibitor with moderate MW and good enzyme and antiviral inhibitory activity. A multicomponent Ugi reaction was utilized to rapidly explore structure–activity relationships within S1', S1, and S2enzyme binding pockets. Moreover, the X-ray structure of SARS-CoV 3CLpro bound with 16-(R) was instrumental in guiding subsequent rounds of chemistry optimization. 16-(R) provides an excellent starting point for the further design and refinement of 3CLpro inhibitors that act by a noncovalent mechanism of action.

  18. Covalent and non-covalent curcumin loading in acid-responsive polymeric micellar nanocarriers

    Science.gov (United States)

    Gao, Min; Chen, Chao; Fan, Aiping; Zhang, Ju; Kong, Deling; Wang, Zheng; Zhao, Yanjun

    2015-07-01

    Poor aqueous solubility, potential degradation, rapid metabolism and elimination lead to low bioavailability of pleiotropic impotent curcumin. Herein, we report two types of acid-responsive polymeric micelles where curcumin was encapsulated via both covalent and non-covalent modes for enhanced loading capacity and on-demand release. Biodegradable methoxy poly(ethylene glycol)-poly(lactic acid) copolymer (mPEG-PLA) was conjugated with curcumin via a hydrazone linker, generating two conjugates differing in architecture (single-tail versus double-tail) and free curcumin was encapsulated therein. The two micelles exhibited similar hydrodynamic size at 95 ± 3 nm (single-tail) and 96 ± 3 nm (double-tail), but their loading capacities differed significantly at 15.0 ± 0.5% (w/w) (single-tail) and 4.8 ± 0.5% (w/w) (double-tail). Under acidic sink conditions (pH 5.0 and 6.0), curcumin displayed a faster release from the single-tail nanocarrier, which was correlated to a low IC50 of 14.7 ± 1.6 (μg mL-1) compared to the value of double-tail micelle (24.9 ± 1.3 μg mL-1) in HeLa cells. The confocal imaging and flow cytometry analysis demonstrated a superior capability of single-tail micelle for intracellular curcumin delivery, which was a consequence of the higher loading capacity and lower degree of mPEG surface coverage. In conclusion, the dual loading mode is an effective means to increase the drug content in the micellar nanocarriers whose delivery efficiency is highly dependent on its polymer-drug conjugate architecture. This strategy offers an alternative nanoplatform for intracellularly delivering impotent hydrophobic agents (i.e. curcumin) in an efficient stimuli-triggered way, which is valuable for the enhancement of curcumin’s efficacy in managing a diverse range of disorders.

  19. Covalent and non-covalent curcumin loading in acid-responsive polymeric micellar nanocarriers

    International Nuclear Information System (INIS)

    Gao, Min; Chen, Chao; Fan, Aiping; Wang, Zheng; Zhao, Yanjun; Zhang, Ju; Kong, Deling

    2015-01-01

    Poor aqueous solubility, potential degradation, rapid metabolism and elimination lead to low bioavailability of pleiotropic impotent curcumin. Herein, we report two types of acid-responsive polymeric micelles where curcumin was encapsulated via both covalent and non-covalent modes for enhanced loading capacity and on-demand release. Biodegradable methoxy poly(ethylene glycol)-poly(lactic acid) copolymer (mPEG-PLA) was conjugated with curcumin via a hydrazone linker, generating two conjugates differing in architecture (single-tail versus double-tail) and free curcumin was encapsulated therein. The two micelles exhibited similar hydrodynamic size at 95 ± 3 nm (single-tail) and 96 ± 3 nm (double-tail), but their loading capacities differed significantly at 15.0 ± 0.5% (w/w) (single-tail) and 4.8 ± 0.5% (w/w) (double-tail). Under acidic sink conditions (pH 5.0 and 6.0), curcumin displayed a faster release from the single-tail nanocarrier, which was correlated to a low IC_5_0 of 14.7 ± 1.6 (μg mL"−"1) compared to the value of double-tail micelle (24.9 ± 1.3 μg mL"−"1) in HeLa cells. The confocal imaging and flow cytometry analysis demonstrated a superior capability of single-tail micelle for intracellular curcumin delivery, which was a consequence of the higher loading capacity and lower degree of mPEG surface coverage. In conclusion, the dual loading mode is an effective means to increase the drug content in the micellar nanocarriers whose delivery efficiency is highly dependent on its polymer–drug conjugate architecture. This strategy offers an alternative nanoplatform for intracellularly delivering impotent hydrophobic agents (i.e. curcumin) in an efficient stimuli-triggered way, which is valuable for the enhancement of curcumin’s efficacy in managing a diverse range of disorders. (paper)

  20. Computer simulation of bounded plasmas

    International Nuclear Information System (INIS)

    Lawson, W.S.

    1987-01-01

    The problems of simulating a one-dimensional bounded plasma system using particles in a gridded space are systematically explored and solutions to them are given. Such problems include the injection of particles at the boundaries, the solution of Poisson's equation, and the inclusion of an external circuit between the confining boundaries. A recently discovered artificial cooling effect is explained as being a side-effect of quiet injection, and its potential for causing serious but subtle errors in bounded simulation is noted. The methods described in the first part of the thesis are then applied to the simulation of an extension of the Pierce diode problem, specifically a Pierce diode modified by an external circuit between the electrodes. The results of these simulations agree to high accuracy with theory when a theory exists, and also show some interesting chaotic behavior in certain parameter regimes. The chaotic behavior is described in detail

  1. Bounded Rationality in Transposition Processes

    DEFF Research Database (Denmark)

    Vollaard, Hans; Martinsen, Dorte Sindbjerg

    2014-01-01

    Studies explaining the timeliness and correctness of the transposition of EU directives into national legislation have provided rather inconclusive findings. They do not offer a clear-cut prediction concerning the transposition of the patients’ rights directive, which is one of the first that con......Studies explaining the timeliness and correctness of the transposition of EU directives into national legislation have provided rather inconclusive findings. They do not offer a clear-cut prediction concerning the transposition of the patients’ rights directive, which is one of the first...... that concerns the organisation and financing of national healthcare systems. This article applies the perspective of bounded rationality to explain (irregularities in) the timely and correct transposition of EU directives. The cognitive and organisational constraints long posited by the bounded rationality...

  2. 78 FR 18326 - Agency Information Collection Activities; Comment Request; Upward Bound and Upward Bound Math...

    Science.gov (United States)

    2013-03-26

    ...; Comment Request; Upward Bound and Upward Bound Math Science Annual Performance Report AGENCY: The Office... considered public records. Title of Collection: Upward Bound and Upward Bound Math Science Annual Performance...) and Upward Bound Math and Science (UBMS) Programs. The Department is requesting a new APR because of...

  3. Spectrum of gluino bound states

    International Nuclear Information System (INIS)

    Chanowitz, M.; Sharpe, S.; California Univ., Berkeley

    1983-01-01

    Using the bag model to first order in αsub(s) we find that if light gluinos exist they will appear as constituents of electrically charged bound states which are stable against strong interaction decay. We review the present experimental constraints and conclude that light, long-lived charged hadrons containing gluinos might exist with lifetimes between 2x10 - 8 and 10 - 14 s. (orig.)

  4. Cyclotron transitions of bound ions

    Science.gov (United States)

    Bezchastnov, Victor G.; Pavlov, George G.

    2017-06-01

    A charged particle in a magnetic field possesses discrete energy levels associated with particle rotation around the field lines. The radiative transitions between these levels are the well-known cyclotron transitions. We show that a bound complex of particles with a nonzero net charge displays analogous transitions between the states of confined motion of the entire complex in the field. The latter bound-ion cyclotron transitions are affected by a coupling between the collective and internal motions of the complex and, as a result, differ from the transitions of a "reference" bare ion with the same mass and charge. We analyze the cyclotron transitions for complex ions by including the coupling within a rigorous quantum approach. Particular attention is paid to comparison of the transition energies and oscillator strengths to those of the bare ion. Selection rules based on integrals of collective motion are derived for the bound-ion cyclotron transitions analytically, and the perturbation and coupled-channel approaches are developed to study the transitions quantitatively. Representative examples are considered and discussed for positive and negative atomic and cluster ions.

  5. Preparation and characterization of malonic acid cross-linked chitosan and collagen 3D scaffolds: an approach on non-covalent interactions.

    Science.gov (United States)

    Mitra, Tapas; Sailakshmi, G; Gnanamani, A; Mandal, A B

    2012-05-01

    The present study emphasizes the influence of non-covalent interactions on the mechanical and thermal properties of the scaffolds of chitosan/collagen origin. Malonic acid (MA), a bifuncitonal diacid was chosen to offer non-covalent cross-linking. Three dimensional scaffolds was prepared using chitosan at 1.0% (w/v) and MA at 0.2% (w/v), similarly collagen 0.5% (w/v) and MA 0.2% (w/v) and characterized. Results on FT-IR, TGA, DSC, SEM and mechanical properties (tensile strength, stiffness, Young's modulus, etc.) assessment demonstrated the existence of non-covalent interaction between MA and chitosan/collagen, which offered flexibility and high strength to the scaffolds suitable for tissue engineering research. Studies using NIH 3T3 fibroblast cells suggested biocompatibility nature of the scaffolds. Docking simulation study further supports the intermolecular hydrogen bonding interactions between MA and chitosan/collagen.

  6. Labeling schemes for bounded degree graphs

    DEFF Research Database (Denmark)

    Adjiashvili, David; Rotbart, Noy Galil

    2014-01-01

    We investigate adjacency labeling schemes for graphs of bounded degree Δ = O(1). In particular, we present an optimal (up to an additive constant) log n + O(1) adjacency labeling scheme for bounded degree trees. The latter scheme is derived from a labeling scheme for bounded degree outerplanar...... graphs. Our results complement a similar bound recently obtained for bounded depth trees [Fraigniaud and Korman, SODA 2010], and may provide new insights for closing the long standing gap for adjacency in trees [Alstrup and Rauhe, FOCS 2002]. We also provide improved labeling schemes for bounded degree...

  7. Non-covalent interactions between thio-caffeine derivatives and water-soluble porphyrin in ethanol-water environment

    Science.gov (United States)

    Lipke, Agnieszka; Makarska-Bialokoz, Magdalena; Sierakowska, Arleta; Jasiewicz, Beata

    2018-03-01

    To determine the binding interactions and ability to form the non-covalent systems, the association process between 5,10,15,20-tetrakis[4-(trimethylammonio)phenyl]-21H,23H-porphine tetra-p-tosylate (H2TTMePP) and a series of five structurally diverse thio-caffeine analogues has been studied in ethanol and ethanol-water solutions, analyzing its absorption and steady-state fluorescence spectra. The porphyrin fluorescence lifetimes in the systems studied were established as well. During the titration with thio-caffeine compounds the slight bathochromic effect and considerable hypochromicity of the porphyrin Soret band maximum can be noted. The fluorescence quenching effect observed for interactions in H2TTMePP - thio-caffeine derivative systems, as well as the order of binding and fluorescence quenching constants (of 105-103 mol- 1) suggest the existence of the mechanism of static quenching due to the formation of non-covalent and non-fluorescent stacking complexes. In all the systems studied the phenomenon of the fractional accessibility of the fluorophore for the quencher was observed as well. Additionally, the specific binding interactions, due to the changes in reaction environment polarity, can be observed. It was found that thio-caffeine compounds can quench the porphyrin fluorescence according to the structure of thio-substituent in caffeine molecule. The obtained results can be potentially useful from scientific, therapeutic or environmental points of view.

  8. Non-covalent attachment of silver nanoclusters onto single-walled carbon nanotubes with human serum albumin as linking molecule

    Energy Technology Data Exchange (ETDEWEB)

    Rodríguez-Galván, Andrés, E-mail: andres.rodriguez@nucleares.unam.mx [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Circuito Exterior C.U., 04510 México D.F. (Mexico); Instituto de Física, Dpto. Física Experimental, Universidad Nacional Autónoma de México, Coyoacán, México, DF 04510 (Mexico); Unidad de Investigación Biomédica en Cáncer INCan-UNAM, Instituto Nacional de Cancerología, México, DF 14080 (Mexico); Heredia, Alejandro [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Circuito Exterior C.U., 04510 México D.F. (Mexico); Amelines-Sarria, Oscar; Rivera, Margarita [Instituto de Física, Dpto. Materia Condensada, Universidad Nacional Autónoma de México, Coyoacán, 04510 México D.F. (Mexico); and others

    2015-03-15

    The attachment of silver nanoclusters (AgNCs) onto single-walled carbon nanotubes (SWNTs) for the formation of integrated fluorescence sites has attracted much attention due their potential applications as biological probes and nanovectors in theragnosis. Here, we report the preparation through assembly of fluorescent quasi 1-D nanomaterial based on SWNTs and silver nanoclusters (AgNCs) non-covalently attached to human serum albumin as biological linker. The fluorescent SWNT–AgNCs–HSA conjugates were characterized by atomic force microscopy, high-resolution transmission electron microscopy (HRTEM), high angle annular dark field scanning TEM (HAADF-STEM), fluorescent and UV–vis spectroscopy. The above techniques confirmed that AgNCs were non-covalently attached onto the external surface of SWNTs. In addition, it was observed that the modification did not affect the optical properties of the synthesized AgNCs since the absorption spectra and fluorescence under UV irradiation (λ = 365 nm) remain the same. The effect of the functionalized systems was tested on mammal red blood cells (RBCs) and it was found that their structural integrity was compromised by the conjugates, limiting their biological and medical applications.

  9. Non-covalent attachment of silver nanoclusters onto single-walled carbon nanotubes with human serum albumin as linking molecule

    International Nuclear Information System (INIS)

    Rodríguez-Galván, Andrés; Heredia, Alejandro; Amelines-Sarria, Oscar; Rivera, Margarita

    2015-01-01

    The attachment of silver nanoclusters (AgNCs) onto single-walled carbon nanotubes (SWNTs) for the formation of integrated fluorescence sites has attracted much attention due their potential applications as biological probes and nanovectors in theragnosis. Here, we report the preparation through assembly of fluorescent quasi 1-D nanomaterial based on SWNTs and silver nanoclusters (AgNCs) non-covalently attached to human serum albumin as biological linker. The fluorescent SWNT–AgNCs–HSA conjugates were characterized by atomic force microscopy, high-resolution transmission electron microscopy (HRTEM), high angle annular dark field scanning TEM (HAADF-STEM), fluorescent and UV–vis spectroscopy. The above techniques confirmed that AgNCs were non-covalently attached onto the external surface of SWNTs. In addition, it was observed that the modification did not affect the optical properties of the synthesized AgNCs since the absorption spectra and fluorescence under UV irradiation (λ = 365 nm) remain the same. The effect of the functionalized systems was tested on mammal red blood cells (RBCs) and it was found that their structural integrity was compromised by the conjugates, limiting their biological and medical applications

  10. Gas-phase noncovalent functionalization of carbon nanotubes with a Ni(II) tetraaza[14]annulene complex

    Science.gov (United States)

    Basiuk, Vladimir A.; Henao-Holguín, Laura Verónica; Álvarez-Zauco, Edgar; Bassiouk, María; Basiuk, Elena V.

    2013-04-01

    The noncovalent functionalization of carbon nanotubes (CNTs) with aromatic polyazamacrocyclic compounds, based on π-π-interactions, keeps the intrinsic electronic structure of CNTs totally intact and allows for combining unique properties of the two interacting components. In addition to porphyrins and phthalocyanines, there are other, simpler compounds exhibiting similar properties, potentially useful for photovoltaic, catalytic and electrochemical applications: for example, tetraaza[14]annulenes. Many of them are highly thermally stable, which makes it possible to employ physical vapor deposition for the preparation of macrocycle-nanotube hybrids. One of such compounds is Ni(II) complex of 5,7,12,14-tetramethyldibenzo-1,4,8,11-tetraazacyclotetradeca-3,5,7,10,12,14-hexaene (also called Ni(II)-tetramethyldibenzotetraaza[14]annulene, or NiTMTAA for simplicity). In the present work, we attempted the noncovalent functionalization of both single-walled and multi-walled CNTs with NiTMTAA in the gas phase at two selected temperatures of 220 and 270 °C, which does not require the use of organic solvents and therefore can be considered as ecologically friendly. The nanohybrids obtained were characterized by means of scanning and transmission electron microscopy, energy dispersive X-ray, Fourier-transform infrared and Raman spectroscopy, as well as thermogravimetric analysis. An additional insight into the structure of adsorption complexes of NiTMTAA on CNTs was provided from density functional theory and molecular mechanics calculations.

  11. Gas-phase noncovalent functionalization of carbon nanotubes with a Ni(II) tetraaza[14]annulene complex

    Energy Technology Data Exchange (ETDEWEB)

    Basiuk, Vladimir A., E-mail: basiuk@nucleares.unam.mx [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, 04510, México D.F. (Mexico); Henao-Holguín, Laura Verónica [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, 04510, México D.F. (Mexico); Álvarez-Zauco, Edgar [Facultad de Ciencias, Universidad Nacional Autónoma de México, Circuito Exterior C.U., 04510, México D.F. (Mexico); Bassiouk, María [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, 04510, México D.F. (Mexico); Basiuk, Elena V. [Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, 04510, México D.F. (Mexico)

    2013-04-01

    The noncovalent functionalization of carbon nanotubes (CNTs) with aromatic polyazamacrocyclic compounds, based on π–π-interactions, keeps the intrinsic electronic structure of CNTs totally intact and allows for combining unique properties of the two interacting components. In addition to porphyrins and phthalocyanines, there are other, simpler compounds exhibiting similar properties, potentially useful for photovoltaic, catalytic and electrochemical applications: for example, tetraaza[14]annulenes. Many of them are highly thermally stable, which makes it possible to employ physical vapor deposition for the preparation of macrocycle–nanotube hybrids. One of such compounds is Ni(II) complex of 5,7,12,14-tetramethyldibenzo-1,4,8,11-tetraazacyclotetradeca-3,5,7,10,12, 14-hexaene (also called Ni(II)-tetramethyldibenzotetraaza[14]annulene, or NiTMTAA for simplicity). In the present work, we attempted the noncovalent functionalization of both single-walled and multi-walled CNTs with NiTMTAA in the gas phase at two selected temperatures of 220 and 270 °C, which does not require the use of organic solvents and therefore can be considered as ecologically friendly. The nanohybrids obtained were characterized by means of scanning and transmission electron microscopy, energy dispersive X-ray, Fourier-transform infrared and Raman spectroscopy, as well as thermogravimetric analysis. An additional insight into the structure of adsorption complexes of NiTMTAA on CNTs was provided from density functional theory and molecular mechanics calculations.

  12. Gas-phase noncovalent functionalization of carbon nanotubes with a Ni(II) tetraaza[14]annulene complex

    International Nuclear Information System (INIS)

    Basiuk, Vladimir A.; Henao-Holguín, Laura Verónica; Álvarez-Zauco, Edgar; Bassiouk, María; Basiuk, Elena V.

    2013-01-01

    The noncovalent functionalization of carbon nanotubes (CNTs) with aromatic polyazamacrocyclic compounds, based on π–π-interactions, keeps the intrinsic electronic structure of CNTs totally intact and allows for combining unique properties of the two interacting components. In addition to porphyrins and phthalocyanines, there are other, simpler compounds exhibiting similar properties, potentially useful for photovoltaic, catalytic and electrochemical applications: for example, tetraaza[14]annulenes. Many of them are highly thermally stable, which makes it possible to employ physical vapor deposition for the preparation of macrocycle–nanotube hybrids. One of such compounds is Ni(II) complex of 5,7,12,14-tetramethyldibenzo-1,4,8,11-tetraazacyclotetradeca-3,5,7,10,12, 14-hexaene (also called Ni(II)-tetramethyldibenzotetraaza[14]annulene, or NiTMTAA for simplicity). In the present work, we attempted the noncovalent functionalization of both single-walled and multi-walled CNTs with NiTMTAA in the gas phase at two selected temperatures of 220 and 270 °C, which does not require the use of organic solvents and therefore can be considered as ecologically friendly. The nanohybrids obtained were characterized by means of scanning and transmission electron microscopy, energy dispersive X-ray, Fourier-transform infrared and Raman spectroscopy, as well as thermogravimetric analysis. An additional insight into the structure of adsorption complexes of NiTMTAA on CNTs was provided from density functional theory and molecular mechanics calculations.

  13. Eight supramolecular assemblies constructed from bis(benzimidazole) and organic acids through strong classical hydrogen bonding and weak noncovalent interactions

    Science.gov (United States)

    Jin, Shouwen; Wang, Daqi

    2014-05-01

    Eight crystalline organic acid-base adducts derived from alkane bridged bis(N-benzimidazole) and organic acids (2,4,6-trinitrophenol, p-nitrobenzoic acid, m-nitrobenzoic acid, 3,5-dinitrobenzoic acid, 5-sulfosalicylic acid and oxalic acid) were prepared and characterized by X-ray diffraction analysis, IR, mp, and elemental analysis. Of the eight compounds five are organic salts (1, 4, 6, 7 and 8) and the other three (2, 3, and 5) are cocrystals. In all of the adducts except 1 and 8, the ratio of the acid and the base is 2:1. All eight supramolecular assemblies involve extensive intermolecular classical hydrogen bonds as well as other noncovalent interactions. The role of weak and strong noncovalent interactions in the crystal packing is ascertained. These weak interactions combined, all the complexes displayed 3D framework structure. The results presented herein indicate that the strength and directionality of the classical N+-H⋯O-, O-H⋯O, and O-H⋯N hydrogen bonds (ionic or neutral) and other nonbonding associations between acids and ditopic benzimidazoles are sufficient to bring about the formation of cocrystals or organic salts.

  14. Honey bee odorant-binding protein 14: effects on thermal stability upon odorant binding revealed by FT-IR spectroscopy and CD measurements.

    Science.gov (United States)

    Schwaighofer, Andreas; Kotlowski, Caroline; Araman, Can; Chu, Nam; Mastrogiacomo, Rosa; Becker, Christian; Pelosi, Paolo; Knoll, Wolfgang; Larisika, Melanie; Nowak, Christoph

    2014-03-01

    In the present work, we study the effect of odorant binding on the thermal stability of honey bee (Apis mellifera L.) odorant-binding protein 14. Thermal denaturation of the protein in the absence and presence of different odorant molecules was monitored by Fourier transform infrared spectroscopy (FT-IR) and circular dichroism (CD). FT-IR spectra show characteristic bands for intermolecular aggregation through the formation of intermolecular β-sheets during the heating process. Transition temperatures in the FT-IR spectra were evaluated using moving-window 2D correlation maps and confirmed by CD measurements. The obtained results reveal an increase of the denaturation temperature of the protein when bound to an odorant molecule. We could also discriminate between high- and low-affinity odorants by determining transition temperatures, as demonstrated independently by the two applied methodologies. The increased thermal stability in the presence of ligands is attributed to a stabilizing effect of non-covalent interactions between odorant-binding protein 14 and the odorant molecule.

  15. Controlling noncovalent interactions between a lysine-rich α-helical peptide and self-assembled monolayers of alkanethiols on Au through functional group diversity

    Energy Technology Data Exchange (ETDEWEB)

    Raigoza, Annette F.; Onyirioha, Kristeen; Webb, Lauren J., E-mail: lwebb@cm.utexas.edu

    2017-02-28

    Highlights: • Functional variety in SAMs control covalent binding of proteins to surfaces. • Peptide density on Au(111) surfaces controlled by SAM functional groups. • Affinity between biomolecule and SAM surface follows a Langmuir isotherm. • Surface chemistry can mimic functional group diversity in proteins and peptides. - Abstract: Reliably attaching a structured biomolecule to an inorganic substrate would enable the preparation of surfaces that incorporate both biological and inorganic functions and structures. To this end, we have previously developed a procedure using the copper(I)-catalyzed click reaction to tether synthetic α-helical peptides carrying two alkyne groups to well-ordered alkanethiol self-assembled monolayers (SAM) on a Au(111) surface, in which the SAM is composed of a mixture of methyl and azide termination. Proteins, however, are composed of many diverse functional groups, and this composition directly effects protein structure, interactions, and reactivity. Here, we explore the utility of mixed SAMs with alternative terminating functional groups to tune and direct the reactivity of the surface through noncovalent peptide-surface interactions. We study both polar surfaces (OH-terminated) and charged surfaces (COOH- and NH{sub 3}-terminated, which are negatively and positively charged, respectively, under our reaction conditions). Surfaces were functionalized with a bipolar peptide composed of Lys and Leu residues that could express different interactions through either hydrophilic and/or charge (Lys) or hydrophobic (Leu) influences. X-ray photoelectron spectroscopy (XPS) and surface infrared spectroscopy were used to characterize surfaces at all stages of the peptide functionalization procedure. This strategy resulted in a high density of surface-bound α-helices without aggregation. Mixed SAMs that included a positively charged alkanethiol along with the azide-terminated thiol resulted in a more efficient reaction and better

  16. Controlling noncovalent interactions between a lysine-rich α-helical peptide and self-assembled monolayers of alkanethiols on Au through functional group diversity

    International Nuclear Information System (INIS)

    Raigoza, Annette F.; Onyirioha, Kristeen; Webb, Lauren J.

    2017-01-01

    Highlights: • Functional variety in SAMs control covalent binding of proteins to surfaces. • Peptide density on Au(111) surfaces controlled by SAM functional groups. • Affinity between biomolecule and SAM surface follows a Langmuir isotherm. • Surface chemistry can mimic functional group diversity in proteins and peptides. - Abstract: Reliably attaching a structured biomolecule to an inorganic substrate would enable the preparation of surfaces that incorporate both biological and inorganic functions and structures. To this end, we have previously developed a procedure using the copper(I)-catalyzed click reaction to tether synthetic α-helical peptides carrying two alkyne groups to well-ordered alkanethiol self-assembled monolayers (SAM) on a Au(111) surface, in which the SAM is composed of a mixture of methyl and azide termination. Proteins, however, are composed of many diverse functional groups, and this composition directly effects protein structure, interactions, and reactivity. Here, we explore the utility of mixed SAMs with alternative terminating functional groups to tune and direct the reactivity of the surface through noncovalent peptide-surface interactions. We study both polar surfaces (OH-terminated) and charged surfaces (COOH- and NH_3-terminated, which are negatively and positively charged, respectively, under our reaction conditions). Surfaces were functionalized with a bipolar peptide composed of Lys and Leu residues that could express different interactions through either hydrophilic and/or charge (Lys) or hydrophobic (Leu) influences. X-ray photoelectron spectroscopy (XPS) and surface infrared spectroscopy were used to characterize surfaces at all stages of the peptide functionalization procedure. This strategy resulted in a high density of surface-bound α-helices without aggregation. Mixed SAMs that included a positively charged alkanethiol along with the azide-terminated thiol resulted in a more efficient reaction and better alignment

  17. Density-functional approaches to noncovalent interactions: a comparison of dispersion corrections (DFT-D), exchange-hole dipole moment (XDM) theory, and specialized functionals.

    Science.gov (United States)

    Burns, Lori A; Vázquez-Mayagoitia, Alvaro; Sumpter, Bobby G; Sherrill, C David

    2011-02-28

    A systematic study of techniques for treating noncovalent interactions within the computationally efficient density functional theory (DFT) framework is presented through comparison to benchmark-quality evaluations of binding strength compiled for molecular complexes of diverse size and nature. In particular, the efficacy of functionals deliberately crafted to encompass long-range forces, a posteriori DFT+dispersion corrections (DFT-D2 and DFT-D3), and exchange-hole dipole moment (XDM) theory is assessed against a large collection (469 energy points) of reference interaction energies at the CCSD(T) level of theory extrapolated to the estimated complete basis set limit. The established S22 [revised in J. Chem. Phys. 132, 144104 (2010)] and JSCH test sets of minimum-energy structures, as well as collections of dispersion-bound (NBC10) and hydrogen-bonded (HBC6) dissociation curves and a pairwise decomposition of a protein-ligand reaction site (HSG), comprise the chemical systems for this work. From evaluations of accuracy, consistency, and efficiency for PBE-D, BP86-D, B97-D, PBE0-D, B3LYP-D, B970-D, M05-2X, M06-2X, ωB97X-D, B2PLYP-D, XYG3, and B3LYP-XDM methodologies, it is concluded that distinct, often contrasting, groups of these elicit the best performance within the accessible double-ζ or robust triple-ζ basis set regimes and among hydrogen-bonded or dispersion-dominated complexes. For overall results, M05-2X, B97-D3, and B970-D2 yield superior values in conjunction with aug-cc-pVDZ, for a mean absolute deviation of 0.41 - 0.49 kcal/mol, and B3LYP-D3, B97-D3, ωB97X-D, and B2PLYP-D3 dominate with aug-cc-pVTZ, affording, together with XYG3/6-311+G(3df,2p), a mean absolute deviation of 0.33 - 0.38 kcal/mol.

  18. The algebras of bounded and essentially bounded Lebesgue measurable functions

    Directory of Open Access Journals (Sweden)

    Mortini Raymond

    2017-04-01

    Full Text Available Let X be a set in ℝn with positive Lebesgue measure. It is well known that the spectrum of the algebra L∞(X of (equivalence classes of essentially bounded, complex-valued, measurable functions on X is an extremely disconnected compact Hausdorff space.We show, by elementary methods, that the spectrum M of the algebra ℒb(X, ℂ of all bounded measurable functions on X is not extremely disconnected, though totally disconnected. Let ∆ = { δx : x ∈ X} be the set of point evaluations and let g be the Gelfand topology on M. Then (∆, g is homeomorphic to (X, Τdis,where Tdis is the discrete topology. Moreover, ∆ is a dense subset of the spectrum M of ℒb(X, ℂ. Finally, the hull h(I, (which is homeomorphic to M(L∞(X, of the ideal of all functions in ℒb(X, ℂ vanishing almost everywhere on X is a nowhere dense and extremely disconnected subset of the Corona M \\ ∆ of ℒb(X, ℂ.

  19. Detection of free and covalently bound microcystins in animal tissues by liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Neffling, Milla-Riina; Lance, Emilie; Meriluoto, Jussi

    2010-03-01

    Microcystins are cyanobacterial hepatotoxins capable of accumulation into animal tissues. The toxins act by inhibiting specific protein phosphatases and both non-covalent and covalent interactions occur. The 2-methyl-3-methoxy-4-phenylbutyric acid (MMPB) method determines the total, i.e. the sum of free and protein-bound microcystin in tissues. The aim of the method development in this paper was to tackle the problems with the MMPB methodology: the rather laborious workflow and the loss of material during different steps of the method. In the optimised workflow the oxidation recovery was of acceptable level (29-40%), the extraction efficiency good (62-97%), but the signal suppression effect from the matrix remained severe in our system (16-37% signal left). The extraction efficiency for the determination of the free, extractable microcystins, was found to be good, 52-100%, depending on the sample and the toxin variant and concentration. Copyright (c) 2009 Elsevier Ltd. All rights reserved.

  20. Voronoi Diagrams Without Bounding Boxes

    Science.gov (United States)

    Sang, E. T. K.

    2015-10-01

    We present a technique for presenting geographic data in Voronoi diagrams without having to specify a bounding box. The method restricts Voronoi cells to points within a user-defined distance of the data points. The mathematical foundation of the approach is presented as well. The cell clipping method is particularly useful for presenting geographic data that is spread in an irregular way over a map, as for example the Dutch dialect data displayed in Figure 2. The automatic generation of reasonable cell boundaries also makes redundant a frequently used solution to this problem that requires data owners to specify region boundaries, as in Goebl (2010) and Nerbonne et al (2011).

  1. Sensitivity analysis using probability bounding

    International Nuclear Information System (INIS)

    Ferson, Scott; Troy Tucker, W.

    2006-01-01

    Probability bounds analysis (PBA) provides analysts a convenient means to characterize the neighborhood of possible results that would be obtained from plausible alternative inputs in probabilistic calculations. We show the relationship between PBA and the methods of interval analysis and probabilistic uncertainty analysis from which it is jointly derived, and indicate how the method can be used to assess the quality of probabilistic models such as those developed in Monte Carlo simulations for risk analyses. We also illustrate how a sensitivity analysis can be conducted within a PBA by pinching inputs to precise distributions or real values

  2. Bounded Densities and Their Derivatives

    DEFF Research Database (Denmark)

    Kozine, Igor; Krymsky, V.

    2009-01-01

    This paper describes how one can compute interval-valued statistical measures given limited information about the underlying distribution. The particular focus is on a bounded derivative of a probability density function and its combination with other available statistical evidence for computing ...... quantities of interest. To be able to utilise the evidence about the derivative it is suggested to adapt the ‘conventional’ problem statement to variational calculus and the way to do so is demonstrated. A number of examples are given throughout the paper....

  3. Removal of bound metal fasteners

    Science.gov (United States)

    Kramer, R. F.

    1981-04-01

    This project explored the removal of bound metal fasteners through the use of ultrasonically assisted wrenches. Two wrenches were designed, fabricated and tested. Previous studies had indicated an increase in thread tension for a given torque application under the influence of ultrasonics. Based on this, the loosening of seized and corroded fasteners with the aid of ultrasonics was explored. Experimental data confirmed our prior analysis of the torque-tension relationship under the influence of ultrasonics; however, our progress did not satisfy the requirements necessary to loosen seized studs in a shipyard environment.

  4. Space mappings with bounded distortion

    CERN Document Server

    Reshetnyak, Yu G

    1989-01-01

    This book is intended for researchers and students concerned with questions in analysis and function theory. The author provides an exposition of the main results obtained in recent years by Soviet and other mathematicians in the theory of mappings with bounded distortion, an active direction in contemporary mathematics. The mathematical tools presented can be applied to a broad spectrum of problems that go beyond the context of the main topic of investigation. For a number of questions in the theory of partial differential equations and the theory of functions with generalized derivatives, this is the first time they have appeared in an internationally distributed monograph.

  5. Influence of non-covalent modification of multiwalled carbon nanotubes on the crystallization behaviour of binary blends of polypropylene and polyamide 6.

    Science.gov (United States)

    Mukhopadhyay, Nabaneeta; Panwar, Ajay S; Kumar, Gulshan; Samajdar, I; Bhattacharyya, Arup R

    2015-02-14

    Blends of polypropylene (PP) and polyamide 6 (PA6) with multiwalled carbon nanotubes (MWNTs) were prepared using different processing strategies in a twin-screw micro-compounder. The effect of MWNTs on the crystallization behaviour of the PP phase and the PA6 phase of the blend has been investigated through non-isothermal crystallization studies by differential scanning calorimetric analysis. Furthermore, the effect of the addition of the compatibilizer (PP-g-MA) and the modification of MWNTs (m-MWNTs) with a non-covalent organic modifier (Li-salt of 6 amino hexanoic acid, Li-AHA) has also been studied in context to the crystallization behaviour of the PP and PA6 phase in the blend. The crystallization studies have indicated a significant increase in bulk crystallization temperature of the PP phase in the blend in the presence of MWNTs. Moreover, the formation of 'trans-lamellar crystalline' structure consisting of PA6 'trans-crystalline lamellae' on MWNTs surface was facilitated in the case of blends prepared via 'protocol 2' as compared to the corresponding blends prepared via 'protocol 1'. Wide angle X-ray diffraction analysis has showed the existence of a β-polymorph of the PP phase due to incorporation of the PA6 phase in the blend. Addition of MWNTs in the blends has facilitated further β-crystalline structure formation of the PP phase. In the presence of m-MWNTs, a higher β-fraction was observed in the PP phase as compared to the blend with pristine MWNTs. Addition of PP-g-MA has suppressed the β-phase formation in the PP phase in the blend. X-ray bulk texture analysis revealed that incorporation of PA6 as well as pristine/modified MWNTs has influenced the extent of orientation of the PP chains towards specific crystalline planes in various blend compositions of PP and PA6.

  6. Synthesis and structure of 1,3-dimethyl-5-(p-sulfonamide-phenylazo)-6-aminouracil and its Ni(II) complex: Topological insights and investigation for noncovalent interactions

    Science.gov (United States)

    Debnath, Diptanu; Roy, Subhadip; Purkayastha, Atanu; Bauzá, Antonio; Choudhury, Rupasree; Ganguly, Rakesh; Frontera, Antonio; Misra, Tarun Kumar

    2017-08-01

    The azo-derivative, 1,3-dimethyl-5-(p-sulfonamide-phenylazo)-6-aminouracil (HL) containing 6-aminouracil (a biomolecule) and sulfonamide functionality (commonly found in sulfa-drugs), and its Ni(II) complex, NiIIL2 were synthesized. Single-crystal X-ray diffraction studies show that the ligand (HL) consists of an E conformation about the azo-linkage with a nearly planar geometry and the complex possesses distorted square planar geometry. The H-bonded underlying networks of HL and NiIIL2 were topologically classified revealing distinct topological types, namely tts and hxl, respectively. Moreover, topology of molecular packings in HL and NiIIL2 has also been discussed. Density functional theory (DFT) calculations, at the M06-2X/def2TZVP level of theory, are employed to characterize a great variety of non-covalent interactions that explicitly show the importance of antiparallel stacking interactions established by π--π+ interactions and H-bonds in the self-assembled dimmers in HL and lp-π/C-H⋯π interactions in NiIIL2. The results of NMR and UV-vis spectroscopies evidence that the ligand exists in hydrazone-imine-keto (B) tautomeric form in solution. The ligand absorption bands consist of the overlapping bands of π→π* and n→π* transitions. The complex experiences electronic transitions that consist of basically ILCT in character with some sort of participation of the atomic d-orbitals of the nickel. The pKa value of the ligand is found to be 4.09.

  7. Determining Normal-Distribution Tolerance Bounds Graphically

    Science.gov (United States)

    Mezzacappa, M. A.

    1983-01-01

    Graphical method requires calculations and table lookup. Distribution established from only three points: mean upper and lower confidence bounds and lower confidence bound of standard deviation. Method requires only few calculations with simple equations. Graphical procedure establishes best-fit line for measured data and bounds for selected confidence level and any distribution percentile.

  8. On semidefinite programming bounds for graph bandwidth

    NARCIS (Netherlands)

    de Klerk, E.; Nagy, M.; Sotirov, R.

    2013-01-01

    In this paper, we propose two new lower bounds on graph bandwidth and cyclic bandwidth based on semidefinite programming (SDP) relaxations of the quadratic assignment problem. We compare the new bounds with two other SDP bounds reported in [A. Blum, G. Konjevod, R. Ravi, and S. Vempala,

  9. Observational Bounds on Cosmic Doomsday

    Energy Technology Data Exchange (ETDEWEB)

    Shmakova, Marina

    2003-07-11

    Recently it was found, in a broad class of models, that the dark energy density may change its sign during the evolution of the universe. This may lead to a global collapse of the universe within the time t{sub c} {approx} 10{sup 10}-10{sup 11} years. Our goal is to find what bounds on the future lifetime of the universe can be placed by the next generation of cosmological observations. As an example, we investigate the simplest model of dark energy with a linear potential V({phi}) = V{sub 0}(1 + {alpha}{phi}). This model can describe the present stage of acceleration of the universe if {alpha} is small enough. However, eventually the field {phi} rolls down, V({phi}) becomes negative, and the universe collapses. The existing observational data indicate that the universe described by this model will collapse not earlier than t{sub c} {approx_equal} 10 billion years from the present moment. We show that the data from SNAP and Planck satellites may extend the bound on the ''doomsday'' time to tc 40 billion years at the 95% confidence level.

  10. Quantum bounds on Bell inequalities

    Science.gov (United States)

    Pál, Károly F.; Vértesi, Tamás

    2009-02-01

    We have determined the maximum quantum violation of 241 tight bipartite Bell inequalities with up to five two-outcome measurement settings per party by constructing the appropriate measurement operators in up to six-dimensional complex and eight-dimensional real-component Hilbert spaces using numerical optimization. Out of these inequalities 129 have been introduced here. In 43 cases higher-dimensional component spaces gave larger violation than qubits, and in three occasions the maximum was achieved with six-dimensional spaces. We have also calculated upper bounds on these Bell inequalities using a method proposed recently. For all but 20 inequalities the best solution found matched the upper bound. Surprisingly, the simplest inequality of the set examined, with only three measurement settings per party, was not among them, despite the high dimensionality of the Hilbert space considered. We also computed detection threshold efficiencies for the maximally entangled qubit pair. These could be lowered in several instances if degenerate measurements were also allowed.

  11. Two supramolecular complexes based on polyoxometalates and Co-EDTA units via covalent connection or non-covalent interaction

    Energy Technology Data Exchange (ETDEWEB)

    Teng, Chunlin; Xiao, Hanxi [Key Laboratory of Theoretical Organic Chemistry and Functional Molecule for Ministry of Education, Hunan University of Science and Technology, Xiangtan 411201 (China); Cai, Qing [Chemistry Department, City University of New York, New York, NY 10016 (United States); Tang, Jianting; Cai, Tiejun [Key Laboratory of Theoretical Organic Chemistry and Functional Molecule for Ministry of Education, Hunan University of Science and Technology, Xiangtan 411201 (China); Deng, Qian, E-mail: dengqian10502@163.com [Key Laboratory of Theoretical Organic Chemistry and Functional Molecule for Ministry of Education, Hunan University of Science and Technology, Xiangtan 411201 (China)

    2016-11-15

    Two new 3D network organic-inorganic hybrid supramolecular complexes ([Na{sub 6}(CoEDTA){sub 2}(H{sub 2}O){sub 13}]·(H{sub 2}SiW{sub 12}O{sub 40})·xH{sub 2}O)n (1) and [CoH{sub 4}EDTA(H{sub 2}O)]{sub 2}(SiW{sub 12}O{sub 40})·15H{sub 2}O (2) (H{sub 4}EDTA=Ethylenediamine tetraacetic acid) have been successfully synthesized by solution method, and characterized by infrared spectrum (IR), thermogravimetric-differential thermal analysis (TG-DTA), cyclic voltammetry (CV) and single{sup −}crystal X-ray diffraction (XRD). Both of the complexes are the supramolecules, but with different liking mode, they are two representative models of supramolecule. complex (1) is a 3D infinite network supramolecular coordination polymer with a rare multi-metal sturcture of sodium-cobalt-containing, which is mainly linked through coordinate-covalent bonds. While complex (2) is normal supramolecule, which linked by non-covalent interactions, such as H-bonding interaction, electrostatic interaction and van der waals force. Both of complex (1) and (2) exhibit good catalytic activities for catalytic oxidation of methanol, when the initial concentration of methanol is 3.0 g m{sup −3}, flow rate is 10 mL min{sup −1}, and the quality of catalyst is 0.2 g, for complex (1) and complex (2) the maximum elimination rates of methanol are 85% (150 °C) and 92% (120 °C), respectively. - Graphical abstract: Two new organic-inorganic hybrid supramolecular complexes based on Co-EDTA, and Keggin polyanions have been successfully synthesized with different pH value by solution method. They are attributed to two representative models of supramolecule. Complex(1) is an infinite coordination polymer with a rare multi-metal sturcture of sodium-cobalt-containing, which is mainly linked through covalent bonds. Complex (2) is a normal supramolecule, which linked by non-covalent interactions of H-bonding interaction, electrostatic interaction and van der waals force. - Highlights: • Two supramolecules

  12. Effects of non-covalent interactions with 5-O-caffeoylquinic acid (chlorogenic acid) on the heat denaturation and solubility of globular proteins

    NARCIS (Netherlands)

    Prigent, S.V.E.; Gruppen, H.; Visser, A.J.W.G.; Koningsveld, G.A. van; Jong, G.A.H. de; Voragen, A.G.J.

    2003-01-01

    The non-covalent interactions between the monomeric phenolic compound chlorogenic acid (5-CQA) and bovine serum albumin (BSA), lysozyme, and α-lactalbumin were characterized, and their effect on protein properties was examined. 5-CQA had a low affinity for all three proteins, and these interactions

  13. Capacity Bounds for Parallel Optical Wireless Channels

    KAUST Repository

    Chaaban, Anas; Rezki, Zouheir; Alouini, Mohamed-Slim

    2016-01-01

    A system consisting of parallel optical wireless channels with a total average intensity constraint is studied. Capacity upper and lower bounds for this system are derived. Under perfect channel-state information at the transmitter (CSIT), the bounds have to be optimized with respect to the power allocation over the parallel channels. The optimization of the lower bound is non-convex, however, the KKT conditions can be used to find a list of possible solutions one of which is optimal. The optimal solution can then be found by an exhaustive search algorithm, which is computationally expensive. To overcome this, we propose low-complexity power allocation algorithms which are nearly optimal. The optimized capacity lower bound nearly coincides with the capacity at high SNR. Without CSIT, our capacity bounds lead to upper and lower bounds on the outage probability. The outage probability bounds meet at high SNR. The system with average and peak intensity constraints is also discussed.

  14. Covalently bound phosphate residues in bovine milk xanthine oxidase and in glucose oxidase from Aspergillus niger: A reevaluation

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, J.L.; Rajagopalan, K.V. (Duke Univ. Medical Center, Durham, NC (USA)); London, R.E. (National Institute of Environmental Health Science, Research Triangle Park, NC (USA))

    1989-09-01

    The reported presence of covalently bound phosphate residues in flavoproteins has significant implications with regard to the catalytic mechanisms and structural stability of the specific enzymes themselves and in terms of general cellular metabolic regulation. These considerations have led to a reevaluation of the presence of covalently bound phosphorus in the flavoproteins xanthine oxidase and glucose oxidase. Milk xanthine oxidase purified by a procedure that includes anion-exchange chromatography is shown to contain three phosphate residues. All three are noncovalently associated with the protein, two with the FAD cofactor, and one with the molybdenum cofactor. Results of chemical analysis and {sup 31}P NMR spectroscopy indicate that enzyme purified by this method contains no phosphoserine residues. Xanthine oxidase preparations purified by chromatography on calcium phosphate gel in place of DEAE-Sephadex yielded higher phosphate-to-protein ratios, which could be reduced to the expected values by additional purification on a folate affinity column. Highly active, highly purified preparations of glucose oxidase are shown to contain only the two phosphate residues of the FAD cofactor. The covalently bound bridging phosphate reported by others may arise in aged or degraded preparations of the enzyme but appears not to be a constituent of functional glucose oxidase. These results suggest that the presence of covalent phosphate residues in other flavoproteins should be rigorously reevaluated as well.

  15. Covalently bound phosphate residues in bovine milk xanthine oxidase and in glucose oxidase from Aspergillus niger: A reevaluation

    International Nuclear Information System (INIS)

    Johnson, J.L.; Rajagopalan, K.V.; London, R.E.

    1989-01-01

    The reported presence of covalently bound phosphate residues in flavoproteins has significant implications with regard to the catalytic mechanisms and structural stability of the specific enzymes themselves and in terms of general cellular metabolic regulation. These considerations have led to a reevaluation of the presence of covalently bound phosphorus in the flavoproteins xanthine oxidase and glucose oxidase. Milk xanthine oxidase purified by a procedure that includes anion-exchange chromatography is shown to contain three phosphate residues. All three are noncovalently associated with the protein, two with the FAD cofactor, and one with the molybdenum cofactor. Results of chemical analysis and 31 P NMR spectroscopy indicate that enzyme purified by this method contains no phosphoserine residues. Xanthine oxidase preparations purified by chromatography on calcium phosphate gel in place of DEAE-Sephadex yielded higher phosphate-to-protein ratios, which could be reduced to the expected values by additional purification on a folate affinity column. Highly active, highly purified preparations of glucose oxidase are shown to contain only the two phosphate residues of the FAD cofactor. The covalently bound bridging phosphate reported by others may arise in aged or degraded preparations of the enzyme but appears not to be a constituent of functional glucose oxidase. These results suggest that the presence of covalent phosphate residues in other flavoproteins should be rigorously reevaluated as well

  16. A Bulky Rhodium Complex Bound to an Adenosine-Adenosine DNA Mismatch: General Architecture of the Metalloinsertion Binding Mode†

    Science.gov (United States)

    Zeglis, Brian M.; Pierre, Valérie C.; Kaiser, Jens T.; Barton, Jacqueline K.

    2009-01-01

    Two crystal structures are determined for Δ-Rh(bpy)2(chrysi)3+ (chrysi = 5,6-chrysenequinone diimine) bound to the oligonucleotide duplex 5′-CGGAAATTACCG-3′ containing two adenosine-adenosine mismatches (italics) through metalloinsertion. Diffraction quality crystals with two different space groups (P3221 and P43212) were obtained under very similar crystallization conditions. In both structures, the bulky rhodium complex inserts into the two mismatched sites from the minor groove side, ejecting the mismatched bases into the major groove. The conformational changes are localized to the mismatched site; the metal complex replaces the mismatched base pair without an increase in base pair rise. The expansive metal complex is accommodated in the duplex by a slight opening in the phosphodiester backbone; all sugars retain a C2′-endo puckering, and flanking base pairs neither stretch nor shear. The structures differ, however, in that in one of the structures, an additional metal complex is bound by intercalation from the major groove at the central 5′-AT-3′ step. We conclude that this additional metal complex is intercalated into this central step because of crystal packing forces. The structures described here of Δ-Rh(bpy)2(chrysi)3+ bound to thermodynamically destabilized AA mismatches share critical features with binding by metalloinsertion in two other oligonucleotides containing different single base mismatches. These results underscore the generality of the metalloinsertion as a new mode of non-covalent binding by small molecules with a DNA duplex. PMID:19374348

  17. Temperature Scanning Stress Relaxation of an Autonomous Self-Healing Elastomer Containing Non-Covalent Reversible Network Junctions

    Directory of Open Access Journals (Sweden)

    Amit Das

    2018-01-01

    Full Text Available In this work, we report about the mechanical relaxation characteristics of an intrinsically self-healable imidazole modified commercial rubber. This kind of self-healing rubber was prepared by melt mixing of 1-butyl imidazole with bromo-butyl rubber (bromine modified isoprene-isobutylene copolymer, BIIR. By this melt mixing process, the reactive allylic bromine of bromo-butyl rubber was converted into imidazole bromide salt. The resulting development of an ionic character to the polymer backbone leads to an ionic association of the groups which ultimately results to the formation of a network structure of the rubber chains. The modified BIIR thus behaves like a robust crosslinked rubber and shows unusual self-healing properties. The non-covalent reversible network has been studied in detail with respect to stress relaxation experiments, scanning electron microscopic and X-ray scattering.

  18. Effect of density variation and non-covalent functionalization on the compressive behavior of carbon nanotube arrays

    Energy Technology Data Exchange (ETDEWEB)

    Misra, A [Instrumentation and Applied Physics, Indian Institute of Science, Bangalore, 560012 (India); Raney, J R; Craig, A E; Daraio, C, E-mail: daraio@caltech.edu [Engineering and Applied Science, California Institute of Technology, Pasadena, CA 91125 (United States)

    2011-10-21

    Arrays of aligned carbon nanotubes (CNTs) have been proposed for different applications, including electrochemical energy storage and shock-absorbing materials. Understanding their mechanical response, in relation to their structural characteristics, is important for tailoring the synthesis method to the different operational conditions of the material. In this paper, we grow vertically aligned CNT arrays using a thermal chemical vapor deposition system, and we study the effects of precursor flow on the structural and mechanical properties of the CNT arrays. We show that the CNT growth process is inhomogeneous along the direction of the precursor flow, resulting in varying bulk density at different points on the growth substrate. We also study the effects of non-covalent functionalization of the CNTs after growth, using surfactant and nanoparticles, to vary the effective bulk density and structural arrangement of the arrays. We find that the stiffness and peak stress of the materials increase approximately linearly with increasing bulk density.

  19. Specific Noncovalent Association of Chiral Large-Ring Hexaimines: Ion Mobility Mass Spectrometry and PM7 Study.

    Science.gov (United States)

    Troć, Anna; Gajewy, Jadwiga; Danikiewicz, Witold; Kwit, Marcin

    2016-09-05

    Ion mobility mass spectrometry and PM7 semiempirical calculations are effective complementary methods to study gas phase formation of noncovalent complexes from vaselike macrocycles. The specific association of large-ring chiral hexaimines, derived from enantiomerically pure trans-1,2-diaminocyclohexane and various isophthaldehydes, is driven mostly by CH-π and π-π stacking interactions. The isotrianglimine macrocycles are prone to form two types of aggregates: tail-to-tail and head-to-head (capsule) dimers. The stability of the tail-to-tail dimers is affected by the size and electronic properties of the substituents at the C-5 position of the aromatic ring. Electron-withdrawing groups stabilize the aggregate, whereas bulky or electron-donating groups destabilize the complexes. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Lithium Enolates in the Enantioselective Construction of Tetrasubstituted Carbon Centers with Chiral Lithium Amides as Noncovalent Stereodirecting Auxiliaries.

    Science.gov (United States)

    Yu, Kai; Lu, Ping; Jackson, Jeffrey J; Nguyen, Thuy-Ai D; Alvarado, Joseph; Stivala, Craig E; Ma, Yun; Mack, Kyle A; Hayton, Trevor W; Collum, David B; Zakarian, Armen

    2017-01-11

    Lithium enolates derived from carboxylic acids are ubiquitous intermediates in organic synthesis. Asymmetric transformations with these intermediates, a central goal of organic synthesis, are typically carried out with covalently attached chiral auxiliaries. An alternative approach is to utilize chiral reagents that form discrete, well-defined aggregates with lithium enolates, providing a chiral environment conducive of asymmetric bond formation. These reagents effectively act as noncovalent, or traceless, chiral auxiliaries. Lithium amides are an obvious choice for such reagents as they are known to form mixed aggregates with lithium enolates. We demonstrate here that mixed aggregates can effect highly enantioselective transformations of lithium enolates in several classes of reactions, most notably in transformations forming tetrasubstituted and quaternary carbon centers. Easy recovery of the chiral reagent by aqueous extraction is another practical advantage of this one-step protocol. Crystallographic, spectroscopic, and computational studies of the central reactive aggregate, which provide insight into the origins of selectivity, are also reported.

  1. VORONOI DIAGRAMS WITHOUT BOUNDING BOXES

    Directory of Open Access Journals (Sweden)

    E. T. K. Sang

    2015-10-01

    Full Text Available We present a technique for presenting geographic data in Voronoi diagrams without having to specify a bounding box. The method restricts Voronoi cells to points within a user-defined distance of the data points. The mathematical foundation of the approach is presented as well. The cell clipping method is particularly useful for presenting geographic data that is spread in an irregular way over a map, as for example the Dutch dialect data displayed in Figure 2. The automatic generation of reasonable cell boundaries also makes redundant a frequently used solution to this problem that requires data owners to specify region boundaries, as in Goebl (2010 and Nerbonne et al (2011.

  2. Spectral computations for bounded operators

    CERN Document Server

    Ahues, Mario; Limaye, Balmohan

    2001-01-01

    Exact eigenvalues, eigenvectors, and principal vectors of operators with infinite dimensional ranges can rarely be found. Therefore, one must approximate such operators by finite rank operators, then solve the original eigenvalue problem approximately. Serving as both an outstanding text for graduate students and as a source of current results for research scientists, Spectral Computations for Bounded Operators addresses the issue of solving eigenvalue problems for operators on infinite dimensional spaces. From a review of classical spectral theory through concrete approximation techniques to finite dimensional situations that can be implemented on a computer, this volume illustrates the marriage of pure and applied mathematics. It contains a variety of recent developments, including a new type of approximation that encompasses a variety of approximation methods but is simple to verify in practice. It also suggests a new stopping criterion for the QR Method and outlines advances in both the iterative refineme...

  3. Instanton bound states in ABJM theory

    Energy Technology Data Exchange (ETDEWEB)

    Hatsuda, Yasuyuki [DESY Hamburg (Germany). Theory Group; Tokyo Institute of Technology (Japan). Dept. of Physics; Moriyama, Sanefumi [Nagoya Univ. (Japan). Kobayashi Maskawa Inst. and Graduate School of Mathematics; Okuyama, Kazumi [Shinshu Univ., Matsumoto, Nagano (Japan). Dept. of Physics

    2013-06-15

    The partition function of the ABJM theory receives non-perturbative corrections due to instanton effects. We study these non-perturbative corrections, including bound states of worldsheet instantons and membrane instantons, in the Fermi-gas approach. We require that the total non-perturbative correction should be always finite for arbitrary Chern-Simons level. This finiteness is realized quite non-trivially because each bound state contribution naively diverges at some levels. The poles of each contribution should be canceled out in total. We use this pole cancellation mechanism to find unknown bound state corrections from known ones. We conjecture a general expression of the bound state contribution. Summing up all the bound state contributions, we find that the effect of bound states is simply incorporated into the worldsheet instanton correction by a redefinition of the chemical potential in the Fermi-gas system. Analytic expressions of the 3- and 4-membrane instanton corrections are also proposed.

  4. Angular-momentum nonclassicality by breaking classical bounds on statistics

    Energy Technology Data Exchange (ETDEWEB)

    Luis, Alfredo [Departamento de Optica, Facultad de Ciencias Fisicas, Universidad Complutense, E-28040 Madrid (Spain); Rivas, Angel [Departamento de Fisica Teorica I, Facultad de Ciencias Fisicas, Universidad Complutense, E-28040 Madrid (Spain)

    2011-10-15

    We derive simple practical procedures revealing the quantum behavior of angular momentum variables by the violation of classical upper bounds on the statistics. Data analysis is minimum and definite conclusions are obtained without evaluation of moments, or any other more sophisticated procedures. These nonclassical tests are very general and independent of other typical quantum signatures of nonclassical behavior such as sub-Poissonian statistics, squeezing, or oscillatory statistics, being insensitive to the nonclassical behavior displayed by other variables.

  5. Bounded elements in Locally C*-algebras

    International Nuclear Information System (INIS)

    El Harti, Rachid

    2001-09-01

    In order to get more useful information about Locally C*-algebras, we introduce in this paper the notion of bounded elements. First, we study the connection between bounded elements and spectrally bounded elements. Some structural results of Locally C*-algebras are established in Theorems 1 , 2 and 3. As an immediate consequence of Theorem 3, we give a characterization of the connected component of the identity in the group of unitary elements for a Locally C*-algebra. (author)

  6. Fuzzy upper bounds and their applications

    Energy Technology Data Exchange (ETDEWEB)

    Soleimani-damaneh, M. [Department of Mathematics, Faculty of Mathematical Science and Computer Engineering, Teacher Training University, 599 Taleghani Avenue, Tehran 15618 (Iran, Islamic Republic of)], E-mail: soleimani_d@yahoo.com

    2008-04-15

    This paper considers the concept of fuzzy upper bounds and provides some relevant applications. Considering a fuzzy DEA model, the existence of a fuzzy upper bound for the objective function of the model is shown and an effective approach to solve that model is introduced. Some dual interpretations are provided, which are useful for practical purposes. Applications of the concept of fuzzy upper bounds in two physical problems are pointed out.

  7. Bounded cohomology of discrete groups

    CERN Document Server

    Frigerio, Roberto

    2017-01-01

    The author manages a near perfect equilibrium between necessary technicalities (always well motivated) and geometric intuition, leading the readers from the first simple definition to the most striking applications of the theory in 13 very pleasant chapters. This book can serve as an ideal textbook for a graduate topics course on the subject and become the much-needed standard reference on Gromov's beautiful theory. -Michelle Bucher The theory of bounded cohomology, introduced by Gromov in the late 1980s, has had powerful applications in geometric group theory and the geometry and topology of manifolds, and has been the topic of active research continuing to this day. This monograph provides a unified, self-contained introduction to the theory and its applications, making it accessible to a student who has completed a first course in algebraic topology and manifold theory. The book can be used as a source for research projects for master's students, as a thorough introduction to the field for graduate student...

  8. Some Improved Nonperturbative Bounds for Fermionic Expansions

    Energy Technology Data Exchange (ETDEWEB)

    Lohmann, Martin, E-mail: marlohmann@gmail.com [Universita di Roma Tre, Dipartimento di Matematica (Italy)

    2016-06-15

    We reconsider the Gram-Hadamard bound as it is used in constructive quantum field theory and many body physics to prove convergence of Fermionic perturbative expansions. Our approach uses a recursion for the amplitudes of the expansion, discovered in a model problem by Djokic (2013). It explains the standard way to bound the expansion from a new point of view, and for some of the amplitudes provides new bounds, which avoid the use of Fourier transform, and are therefore superior to the standard bounds for models like the cold interacting Fermi gas.

  9. Matrix Isolation and ab initio study of the noncovalent complexes between formamide and acetylene.

    Science.gov (United States)

    Mardyukov, Artur; Sánchez-García, Elsa; Sander, Wolfram

    2009-02-12

    Matrix isolation spectroscopy in combination with ab initio calculations is a powerful technique for the identification of weakly bound intermolecular complexes. Here, weak complexes between formamide and acetylene are studied, and three 1:1 complexes with binding energies of -2.96, -2.46, and -1.79 kcal/mol have been found at the MP2 level of theory (MP2/cc-pVTZ + ZPE + BSSE). The two most stable dimers A and B are identified in argon and nitrogen matrices by comparison between the experimental and calculated infrared frequencies. Both complexes are stabilized by the formamide C=O...HC acetylene and H...pi interactions. Large shifts have been observed experimentally for the C-H stretching vibrations of the acetylene molecule, in very good agreement with the calculated values. Eight 1:2 FMA-acetylene trimers (T-A to T-H) with binding energies between -5.44 and -2.62 kcal/mol (MP2/aug-cc-pVDZ + ZPE + BSSE) were calculated. The two most stable trimers T-A and T-B are very close in energy and have similar infrared spectra. Several weak bands that are in agreement with the calculated frequencies of the trimers T-A and T-B are observed under matrix isolation conditions. However, the differences are too small for a definitive assignment.

  10. Variational lower bound on the scattering length

    International Nuclear Information System (INIS)

    Rosenberg, L.; Spruch, L.

    1975-01-01

    The scattering length A characterizes the zero-energy scattering of one system by another. It was shown some time ago that a variational upper bound on A could be obtained using methods, of the Rayleigh-Ritz type, which are commonly employed to obtain upper bounds on energy eigenvalues. Here we formulate a method for obtaining a variational lower bound on A. Once again the essential idea is to express the scattering length as a variational estimate plus an error term and then to reduce the problem of bounding the error term to one involving bounds on energy eigenvalues. In particular, the variational lower bound on A is rigorously established provided a certin modified Hamiltonian can be shown to have no discrete states lying below the level of the continuum threshold. It is unfortunately true that necessary conditions for the existence of bound states are not available for multiparticle systems in general. However, in the case of positron-atom scattering the adiabatic approximation can be introduced as an (essentially) solvable comparison problem to rigorously establish the nonexistence of bound states of the modified Hamiltonian. It has recently been shown how the validity of the variational upper bound on A can be maintained when the target ground-state wave function is imprecisely known. Similar methods can be used to maintain the variational lower bound on A. Since the bound is variational, the error in the calculated scattering length will be of second order in the error in the wave function. The use of the adiabatic approximation in the present context places no limitation in principle on the accuracy achievable

  11. Effect of Telecollaboration on Translation of Culture-Bound Texts

    Directory of Open Access Journals (Sweden)

    Vahid Rafieyan

    2016-07-01

    Full Text Available One of the most problematic perspectives of translation phenomenon is the cultural gap between the source language and the target language (Yang, 2010. This gap can be ideally filled through telecollaboration which provides internationally dispersed language learners in parallel language classes with cost-effective access to, and engagement with, peers who are expert speakers of the language under study (Belz, 2005. To investigate the effect of telecollaboration on the quality of translation of culture-bound texts, the current study was conducted on 64 Iranian undergraduate students of English translation at a university in Iran. Instruments used in the study consisted of three texts containing news excerpts from Voice of America (VOA. The study consisted of three phases: 1 assessing quality of translation of culture-bound texts, 2 random assignment of participants to two groups: one merely receiving cultural instruction while the other being linked to native English speakers through LinkedIn alongside receiving cultural instruction, and 3 assessing quality of translation of culture-bound texts immediately and two months following treatment. The results of mixed between-within subjects analysis of variance revealed the significant positive effect of telecollaboration on developing quality of translation of culture-bound texts and sustaining the attained knowledge. The pedagogical implications of the findings suggested incorporation of cultural components of source language society into translation courses and providing opportunities for translation students to be exposed to authentic and intensive source language culture through telecollaboration.

  12. Quantum chemical investigation of attractive non-covalent interactions between halomethanes and rare gases.

    Science.gov (United States)

    McAllister, Linda J; Bruce, Duncan W; Karadakov, Peter B

    2012-11-01

    The interaction between rare gas atoms and trifluoromethylhalides and iodomethane is investigated using ab initio and density functional theory (DFT) methods: MP2, CCSD, B3LYP, M06, M06-L, M06-2X, M06-HF, X3LYP, PBE, B97-D, B3LYP-D3, and M06-L-D3, in combination with the aug-cc-pVTZ and aug-cc-pVTZ-PP basis sets. A weakly attractive interaction is observed for all complexes, whose strength increases as the rare gas and halogen bond donor become more polarizable, and as the group bound to the halogen bond donor becomes more electron-withdrawing. The separation between iodine and krypton in the complex CF(3)I···Kr, calculated at the MP2 and B3LYP-D3 levels of theory, agrees very well with recent experimental results (Stephens, S. L.; Walker, N. R.; Legon, A. C. J. Chem. Phys. 2011, 135, 224309). Analysis of the ability of theoretical methods to account for the dispersion interaction present in these complexes leads to the conclusion that MP2 and B3LYP-D3, which produce very similar results, are the better performing methods, followed by B97-D and the M06 suite of functionals; the popular B3LYP as well as X3LYP perform poorly and significantly underestimate the interaction strength. The orbitals responsible for the interaction are identified through Edmiston-Ruedenberg localization; it is shown that, by combining the key orbitals, it is possible to observe a molecular orbital picture of a σ-hole interaction.

  13. Stacked spheres and lower bound theorem

    Indian Academy of Sciences (India)

    BASUDEB DATTA

    2011-11-20

    Nov 20, 2011 ... Preliminaries. Lower bound theorem. On going work. Definitions. An n-simplex is a convex hull of n + 1 affinely independent points. (called vertices) in some Euclidean space R. N . Stacked spheres and lower bound theorem. Basudeb Datta. Indian Institute of Science. 2 / 27 ...

  14. A strongly quasiconvex PAC-Bayesian bound

    DEFF Research Database (Denmark)

    Thiemann, Niklas; Igel, Christian; Wintenberger, Olivier

    2017-01-01

    We propose a new PAC-Bayesian bound and a way of constructing a hypothesis space, so that the bound is convex in the posterior distribution and also convex in a trade-off parameter between empirical performance of the posterior distribution and its complexity. The complexity is measured by the Ku...

  15. On the range of completely bounded maps

    Directory of Open Access Journals (Sweden)

    Richard I. Loebl

    1978-01-01

    Full Text Available It is shown that if every bounded linear map from a C*-algebra α to a von Neumann algebra β is completely bounded, then either α is finite-dimensional or β⫅⊗Mn, where is a commutative von Neumann algebra and Mn is the algebra of n×n complex matrices.

  16. Bounds in the location-allocation problem

    DEFF Research Database (Denmark)

    Juel, Henrik

    1981-01-01

    Develops a family of stronger lower bounds on the objective function value of the location-allocation problem. Solution methods proposed to solve problems in location-allocation; Efforts to develop a more efficient bound solution procedure; Determination of the locations of the sources....

  17. Experimental evidence for bounds on quantum correlations.

    Science.gov (United States)

    Bovino, F A; Castagnoli, G; Degiovanni, I P; Castelletto, S

    2004-02-13

    We implemented the experiment proposed by Cabello in the preceding Letter to test the bounds of quantum correlation. As expected from the theory we found that, for certain choices of local observables, Tsirelson's bound of the Clauser-Horne-Shimony-Holt inequality (2 x square root of 2) is not reached by any quantum states.

  18. Exponential Lower Bounds For Policy Iteration

    OpenAIRE

    Fearnley, John

    2010-01-01

    We study policy iteration for infinite-horizon Markov decision processes. It has recently been shown policy iteration style algorithms have exponential lower bounds in a two player game setting. We extend these lower bounds to Markov decision processes with the total reward and average-reward optimality criteria.

  19. Conductivity bound from dirty black holes

    Energy Technology Data Exchange (ETDEWEB)

    Bitaghsir Fadafan, Kazem, E-mail: bitaghsir@shahroodut.ac.ir

    2016-11-10

    We propose a lower bound of the dc electrical conductivity in strongly disordered, strongly interacting quantum field theories using holography. We study linear response of black holes with broken translational symmetry in Einstein–Maxwell-dilaton theories of gravity. Using the generalized Stokes equations at the horizon, we derive the lower bound of the electrical conductivity for the dual two dimensional disordered field theory.

  20. No-arbitrage bounds for financial scenarios

    DEFF Research Database (Denmark)

    Geyer, Alois; Hanke, Michael; Weissensteiner, Alex

    2014-01-01

    We derive no-arbitrage bounds for expected excess returns to generate scenarios used in financial applications. The bounds allow to distinguish three regions: one where arbitrage opportunities will never exist, a second where arbitrage may be present, and a third, where arbitrage opportunities...

  1. New bounds on isotropic Lorentz violation

    International Nuclear Information System (INIS)

    Carone, Christopher D.; Sher, Marc; Vanderhaeghen, Marc

    2006-01-01

    Violations of Lorentz invariance that appear via operators of dimension four or less are completely parametrized in the Standard Model Extension (SME). In the pure photonic sector of the SME, there are 19 dimensionless, Lorentz-violating parameters. Eighteen of these have experimental upper bounds ranging between 10 -11 and 10 -32 ; the remaining parameter, k-tilde tr , is isotropic and has a much weaker bound of order 10 -4 . In this Brief Report, we point out that k-tilde tr gives a significant contribution to the anomalous magnetic moment of the electron and find a new upper bound of order 10 -8 . With reasonable assumptions, we further show that this bound may be improved to 10 -14 by considering the renormalization of other Lorentz-violating parameters that are more tightly constrained. Using similar renormalization arguments, we also estimate bounds on Lorentz-violating parameters in the pure gluonic sector of QCD

  2. Covariant entropy bound and loop quantum cosmology

    International Nuclear Information System (INIS)

    Ashtekar, Abhay; Wilson-Ewing, Edward

    2008-01-01

    We examine Bousso's covariant entropy bound conjecture in the context of radiation filled, spatially flat, Friedmann-Robertson-Walker models. The bound is violated near the big bang. However, the hope has been that quantum gravity effects would intervene and protect it. Loop quantum cosmology provides a near ideal setting for investigating this issue. For, on the one hand, quantum geometry effects resolve the singularity and, on the other hand, the wave function is sharply peaked at a quantum corrected but smooth geometry, which can supply the structure needed to test the bound. We find that the bound is respected. We suggest that the bound need not be an essential ingredient for a quantum gravity theory but may emerge from it under suitable circumstances.

  3. MP2.5 and MP2.X: Approaching CCSD(T) Quality Description of Noncovalent Interaction at the Cost of a Single CCSD Iteration

    Czech Academy of Sciences Publication Activity Database

    Sedlák, Robert; Riley, K. E.; Řezáč, Jan; Pitoňák, M.; Hobza, Pavel

    2013-01-01

    Roč. 14, č. 4 (2013), s. 698-707 ISSN 1439-4235 R&D Projects: GA ČR GBP208/12/G016 Grant - others:European Social Fund(XE) CZ1.05/2.1.00/03/0058 Institutional support: RVO:61388963 Keywords : benchmark dataset * complete basis set limit * correlation energy * MOllerPlesset perturbation theory * noncovalent interactions Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.360, year: 2013

  4. The aug-cc-pVnZ-F12 basis set family: Correlation consistent basis sets for explicitly correlated benchmark calculations on anions and noncovalent complexes.

    Science.gov (United States)

    Sylvetsky, Nitai; Kesharwani, Manoj K; Martin, Jan M L

    2017-10-07

    We have developed a new basis set family, denoted as aug-cc-pVnZ-F12 (or aVnZ-F12 for short), for explicitly correlated calculations. The sets included in this family were constructed by supplementing the corresponding cc-pVnZ-F12 sets with additional diffuse functions on the higher angular momenta (i.e., additional d-h functions on non-hydrogen atoms and p-g on hydrogen atoms), optimized for the MP2-F12 energy of the relevant atomic anions. The new basis sets have been benchmarked against electron affinities of the first- and second-row atoms, the W4-17 dataset of total atomization energies, the S66 dataset of noncovalent interactions, the Benchmark Energy and Geometry Data Base water cluster subset, and the WATER23 subset of the GMTKN24 and GMTKN30 benchmark suites. The aVnZ-F12 basis sets displayed excellent performance, not just for electron affinities but also for noncovalent interaction energies of neutral and anionic species. Appropriate CABSs (complementary auxiliary basis sets) were explored for the S66 noncovalent interaction benchmark: between similar-sized basis sets, CABSs were found to be more transferable than generally assumed.

  5. Non-covalent interactions of the carcinogen (+)-anti-BPDE with exon 1 of the human K-ras proto-oncogene

    Science.gov (United States)

    Rodriguez, Jorge H.; Deligkaris, Christos

    2013-03-01

    Investigating the complementary, but different, effects of physical (non-covalent) and chemical (covalent) mutagen-DNA and carcinogen-DNA interactions is important for understanding possible mechanisms of development and prevention of mutagenesis and carcinogenesis. A highly mutagenic and carcinogenic metabolite of the polycyclic aromatic hydrocarbon benzo[ α]pyrene, namely (+)-anti-BPDE, is known to undergo both physical and chemical complexation with DNA. The major covalent adduct, a promutagenic, is known to be an external (+)-trans-anti-BPDE-N2-dGuanosine configuration whose origins are not fully understood. Thus, it is desirable to study the mechanisms of external non-covalent BPDE-DNA binding and their possible relationships to external covalent trans adduct formation. We present a detailed codon-by-codon computational study of the non-covalent interactions of (+)-anti-BPDE with DNA which explains and correctly predicts preferential (+)-anti-BPDE binding at minor groove guanosines. Due to its relevance to carcinogenesis, the interaction of (+)-anti-BPDE with exon 1 of the human K-ras gene has been studied in detail. Present address: Department of Physics, Drury University

  6. Recognition of anions using urea and thiourea substituted calixarenes: A density functional theory study of non-covalent interactions

    Science.gov (United States)

    Athar, Mohd; Lone, Mohsin Y.; Jha, Prakash C.

    2018-02-01

    Designing of new calixarene receptors for the selective binding of anions is an age-old concept; even though expected outcomes from this field are at premature stage. Herein, we have performed quantum chemical calculations to provide structural basis of anion binding with urea and thiourea substituted calixarenes (1, 2, and 3). In particular, spherical halides (F-, Cl-, Br-) and linear anions (CN-, N3-, SCN-) were modelled for calculating binding energies with receptor 1, 2 and 3 followed by their marked IR vibrations; taking the available experimental information into account. We found that the thiourea substitutions have better capability to stabilize the anions. Results have suggested that the structural behaviour of macrocyclic motifs were responsible for displaying the anion binding potentials. Moreover, second order "charge transfer" interactions of n-σ∗NH and n-σ∗OH type along the H-bond axis played critical role in developing hydrogen bonds. The present work also examines the role of non-covalent interactions (NCI) and their effects on thermodynamic and chemical-reactivity descriptors.

  7. Capillaries modified by noncovalent anionic polymer adsorption for capillary zone electrophoresis, micellar electrokinetic capillary chromatography and capillary electrophoresis mass spectrometry

    DEFF Research Database (Denmark)

    Bendahl, L; Hansen, S H; Gammelgaard, Bente

    2001-01-01

    A simple coating procedure for generation of a high and pH-independent electroosmotic flow in capillary zone electrophoresis (CZE) and micellar electrokinetic capillary chromatography (MEKC) is described. The bilayer coating was formed by noncovalent adsorption of the ionic polymers Polybrene...... capillaries was (4.9+/-0.1) x 10(-4) cm2V(-1)s(-1) in a pH-range of 2-10 (ionic strength = 30 mM). When alkaline compounds were used as test substances intracapillary and intercapillary migration time variations (n = 6) were less than 1% relative standard deviation (RSD) and 2% RSD, respectively in the entire...... pH range. The coating was fairly stable in the presence of sodium dodecyl sulfate, and this made it possible to perform fast MEKC separations at low pH. When neutral compounds were used as test substances, the intracapillary migration time variations (n = 6) were less than 2% RSD in a pH range of 2...

  8. Noncovalent Pi-Pi Stacking at the Carbon-Electrolyte Interface: Controlling the Voltage Window of Electrochemical Supercapacitors.

    Science.gov (United States)

    Li, Mengya; Westover, Andrew S; Carter, Rachel; Oakes, Landon; Muralidharan, Nitin; Boire, Timothy C; Sung, Hak-Joon; Pint, Cary L

    2016-08-03

    A key parameter in the operation of an electrochemical double-layer capacitor is the voltage window, which dictates the device energy density and power density. Here we demonstrate experimental evidence that π-π stacking at a carbon-ionic liquid interface can modify the operation voltage of a supercapacitor device by up to 30%, and this can be recovered by steric hindrance at the electrode-electrolyte interface introduced by poly(ethylene oxide) polymer electrolyte additives. This observation is supported by Raman spectroscopy, electrochemical impedance spectroscopy, and differential scanning calorimetry that each independently elucidates the signature of π-π stacking between imidazole groups in the ionic liquid and the carbon surface and the role this plays to lower the energy barrier for charge transfer at the electrode-electrolyte interface. This effect is further observed universally across two separate ionic liquid electrolyte systems and is validated by control experiments showing an invariant electrochemical window in the absence of a carbon-ionic liquid electrode-electrolyte interface. As interfacial or noncovalent interactions are usually neglected in the mechanistic picture of double-layer capacitors, this work highlights the importance of understanding chemical properties at supercapacitor interfaces to engineer voltage and energy capability.

  9. The BioFragment Database (BFDb): An open-data platform for computational chemistry analysis of noncovalent interactions

    Science.gov (United States)

    Burns, Lori A.; Faver, John C.; Zheng, Zheng; Marshall, Michael S.; Smith, Daniel G. A.; Vanommeslaeghe, Kenno; MacKerell, Alexander D.; Merz, Kenneth M.; Sherrill, C. David

    2017-10-01

    Accurate potential energy models are necessary for reliable atomistic simulations of chemical phenomena. In the realm of biomolecular modeling, large systems like proteins comprise very many noncovalent interactions (NCIs) that can contribute to the protein's stability and structure. This work presents two high-quality chemical databases of common fragment interactions in biomolecular systems as extracted from high-resolution Protein DataBank crystal structures: 3380 sidechain-sidechain interactions and 100 backbone-backbone interactions that inaugurate the BioFragment Database (BFDb). Absolute interaction energies are generated with a computationally tractable explicitly correlated coupled cluster with perturbative triples [CCSD(T)-F12] "silver standard" (0.05 kcal/mol average error) for NCI that demands only a fraction of the cost of the conventional "gold standard," CCSD(T) at the complete basis set limit. By sampling extensively from biological environments, BFDb spans the natural diversity of protein NCI motifs and orientations. In addition to supplying a thorough assessment for lower scaling force-field (2), semi-empirical (3), density functional (244), and wavefunction (45) methods (comprising >1M interaction energies), BFDb provides interactive tools for running and manipulating the resulting large datasets and offers a valuable resource for potential energy model development and validation.

  10. Sacrificial spacer and non-covalent routes toward the molecular imprinting of 'poorly-functionalized' N-heterocycles

    International Nuclear Information System (INIS)

    Kirsch, N.; Alexander, C.; Davies, S.; Whitcombe, M.J.

    2004-01-01

    A comparison of three different methods for the imprinting of small aromatic heterocycles containing only a single nitrogen atom, for the preparation of specific analytical phases, was carried out. A conventional non-covalent approach to the imprinting of pyridine using methacrylic acid as the functional monomer was compared with two sacrificial spacer methods, in which heterocycles were imprinted as covalent template analogues. The results of binding experiments showed that discrimination based on ligand size was possible when polymers were prepared using a silyl ester-based template. The most selective polymer was able to bind pyridine in preference to quinoline or acridine which is opposite to the trend predicted by the pK HB values for the three ligands. Curve fitting of the isotherm for pyridine binding to this polymer to the Langmuir model gave an approximate K d of 1.1±0.1 mM and a binding site concentration of 57±2 mmol g -1 . Acridine binding did not show saturation behaviour and was non-specific and cooperative in nature

  11. Non-covalent functionalization of carbon nanotubes: Controlling Chirality Selectivity via Alkyl Groups of Conjugated Co-Polymers

    Science.gov (United States)

    Weight, Braden; Gifford, Brendan; Kilina, Svetlana

    Carbon nanotubes (CNTs) play an important role in nanotechnology, including electronics, chemical sensors, and solar cells. Their electronic and optical properties depend on the size and geometry (chirality) of the nanotube. However, one main concern regarding nanotube application in optoelectronic devices is the difficulty of separating them based upon chirality after synthesis, as all known synthesis methods produce more than one chirality simultaneously. To get around this, one method is the functionalization of the CNTs via non-covalent bonding of co-polymers by wrapping them around the tube. We use force field simulations to explore the effects of various structural manipulations to the co-polymer 9,9-dialkylfluorenyl-2,7-diyl bipyridine (PFO-BPY) to find the preferential mechanisms of selective interactions between the PFO-BPY and CNTs of various chiralities. In particular, we focus on the effect of the branching in alkyl side-groups of PFO-BPY on their binding to the CNT surface. We have observed correlations between the side-group structures and their wrapping morphology on the CNT-Polymer interactions. Our calculations demonstrate that the branching in the position closest to the conjugated backboned results in the strongest interaction with all CNT. This research was supported by the National Science Foundation (CHE 1413614) and the Center for Computationally-Assisted Science and Technology at NDSU.

  12. Non-Covalent Interactions and Impact of Charge Penetration Effects in Linear Oligoacene Dimers and Single Crystals

    KAUST Repository

    Ryno, Sean

    2016-05-18

    Non-covalent interactions determine in large part the thermodynamic aspects of molecular packing in organic crystals. Using a combination of symmetry-adapted perturbation theory (SAPT) and classical multipole electrostatics, we describe the interaction potential energy surfaces for dimers of the oligoacene family, from benzene to hexacene. An analysis of these surfaces and a thorough assessment of dimers extracted from the reported crystal structures underline that high-order interactions (i.e., three-body non-additive interactions) must be considered in order to rationalize the details of the crystal structures. A comparison of the SAPT electrostatic energy with the multipole interaction energy demonstrates the importance of the contribution of charge penetration, which is shown to account for up to 50% of the total interaction energy in dimers extracted from the experimental single crystals; in the case of the most stable co-facial model dimers, this contribution is even larger than the total interaction energy. Our results highlight the importance of taking account of charge penetration in studies of the larger oligoacenes.

  13. Sacrificial spacer and non-covalent routes toward the molecular imprinting of 'poorly-functionalized' N-heterocycles

    Energy Technology Data Exchange (ETDEWEB)

    Kirsch, N.; Alexander, C.; Davies, S.; Whitcombe, M.J

    2004-02-16

    A comparison of three different methods for the imprinting of small aromatic heterocycles containing only a single nitrogen atom, for the preparation of specific analytical phases, was carried out. A conventional non-covalent approach to the imprinting of pyridine using methacrylic acid as the functional monomer was compared with two sacrificial spacer methods, in which heterocycles were imprinted as covalent template analogues. The results of binding experiments showed that discrimination based on ligand size was possible when polymers were prepared using a silyl ester-based template. The most selective polymer was able to bind pyridine in preference to quinoline or acridine which is opposite to the trend predicted by the pK{sub HB} values for the three ligands. Curve fitting of the isotherm for pyridine binding to this polymer to the Langmuir model gave an approximate K{sub d} of 1.1{+-}0.1 mM and a binding site concentration of 57{+-}2 mmol g{sup -1}. Acridine binding did not show saturation behaviour and was non-specific and cooperative in nature.

  14. Detection of free and covalently bound microcystins in animal tissues by liquid chromatography-tandem mass spectrometry

    International Nuclear Information System (INIS)

    Neffling, Milla-Riina; Lance, Emilie; Meriluoto, Jussi

    2010-01-01

    Microcystins are cyanobacterial hepatotoxins capable of accumulation into animal tissues. The toxins act by inhibiting specific protein phosphatases and both non-covalent and covalent interactions occur. The 2-methyl-3-methoxy-4-phenylbutyric acid (MMPB) method determines the total, i.e. the sum of free and protein-bound microcystin in tissues. The aim of the method development in this paper was to tackle the problems with the MMPB methodology: the rather laborious workflow and the loss of material during different steps of the method. In the optimised workflow the oxidation recovery was of acceptable level (29-40%), the extraction efficiency good (62-97%), but the signal suppression effect from the matrix remained severe in our system (16-37% signal left). The extraction efficiency for the determination of the free, extractable microcystins, was found to be good, 52-100%, depending on the sample and the toxin variant and concentration. - The study concerns method development for the LC-MS-MS analysis of both free and protein-bound microcystin in tissue materials.

  15. Detection of free and covalently bound microcystins in animal tissues by liquid chromatography-tandem mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Neffling, Milla-Riina, E-mail: mneffling@gmail.co [Department of Biochemistry and Pharmacy, Abo Akademi University, Tykistoekatu 6 A, Biocity 3rd floor, FI-20520, Turku (Finland); Lance, Emilie [UMR CNRS Ecobio 6553, University of Rennes 1, Avenue du General Leclerc, 35042, Rennes Cedex (France); Meriluoto, Jussi [Department of Biochemistry and Pharmacy, Abo Akademi University, Tykistoekatu 6 A, Biocity 3rd floor, FI-20520, Turku (Finland)

    2010-03-15

    Microcystins are cyanobacterial hepatotoxins capable of accumulation into animal tissues. The toxins act by inhibiting specific protein phosphatases and both non-covalent and covalent interactions occur. The 2-methyl-3-methoxy-4-phenylbutyric acid (MMPB) method determines the total, i.e. the sum of free and protein-bound microcystin in tissues. The aim of the method development in this paper was to tackle the problems with the MMPB methodology: the rather laborious workflow and the loss of material during different steps of the method. In the optimised workflow the oxidation recovery was of acceptable level (29-40%), the extraction efficiency good (62-97%), but the signal suppression effect from the matrix remained severe in our system (16-37% signal left). The extraction efficiency for the determination of the free, extractable microcystins, was found to be good, 52-100%, depending on the sample and the toxin variant and concentration. - The study concerns method development for the LC-MS-MS analysis of both free and protein-bound microcystin in tissue materials.

  16. Continuous bounded cohomology of locally compact groups

    CERN Document Server

    2001-01-01

    Recent research has repeatedly led to connections between important rigidity questions and bounded cohomology. However, the latter has remained by and large intractable. This monograph introduces the functorial study of the continuous bounded cohomology for topological groups, with coefficients in Banach modules. The powerful techniques of this more general theory have successfully solved a number of the original problems in bounded cohomology. As applications, one obtains, in particular, rigidity results for actions on the circle, for representations on complex hyperbolic spaces and on Teichmüller spaces. A special effort has been made to provide detailed proofs or references in quite some generality.

  17. Positivity bounds on double parton distributions

    International Nuclear Information System (INIS)

    Diehl, Markus; Kasemets, Tomas

    2013-03-01

    Double hard scattering in proton-proton collisions is described in terms of double parton distributions. We derive bounds on these distributions that follow from their interpretation as probability densities, taking into account all possible spin correlations between two partons in an unpolarized proton. These bounds constrain the size of the polarized distributions and can for instance be used to set upper limits on the effects of spin correlations in double hard scattering. We show that the bounds are stable under leading-order DGLAP evolution to higher scales.

  18. Remarks on Bousso's covariant entropy bound

    CERN Document Server

    Mayo, A E

    2002-01-01

    Bousso's covariant entropy bound is put to the test in the context of a non-singular cosmological solution of general relativity found by Bekenstein. Although the model complies with every assumption made in Bousso's original conjecture, the entropy bound is violated due to the occurrence of negative energy density associated with the interaction of some the matter components in the model. We demonstrate how this property allows for the test model to 'elude' a proof of Bousso's conjecture which was given recently by Flanagan, Marolf and Wald. This corroborates the view that the covariant entropy bound should be applied only to stable systems for which every matter component carries positive energy density.

  19. The bound state problem and quark confinement

    International Nuclear Information System (INIS)

    Chaichian, M.; Demichev, A.P.; Nelipa, N.F.

    1980-01-01

    A quantum field-theoretic model in which quark is confined is considered. System of equations for the Green functions of colour singlet and octet bound states is obtained. The method is based on the nonperturbative Schwinger-Dyson equations with the use of Slavnov-Taylor identities. It is shown that in the framework of the model if there exist singlet, then also exist octet bound states of the quark-antiquark system. Thus in general, confinement of free quarks does not mean absence of their coloured bound states. (author)

  20. Quasi-bound states in continuum

    International Nuclear Information System (INIS)

    Nakamura, Hiroaki; Hatano, Naomichi; Garmon, Sterling; Petrosky, Tomio

    2007-08-01

    We report the prediction of quasi-bound states (resonant states with very long lifetimes) that occur in the eigenvalue continuum of propagating states for a wide region of parameter space. These quasi-bound states are generated in a quantum wire with two channels and an adatom, when the energy bands of the two channels overlap. A would-be bound state that lays just below the upper energy band is slightly destabilized by the lower energy band and thereby becomes a resonant state with a very long lifetime (a second QBIC lays above the lower energy band). (author)

  1. Revealing Ligand Binding Sites and Quantifying Subunit Variants of Noncovalent Protein Complexes in a Single Native Top-Down FTICR MS Experiment

    Science.gov (United States)

    Li, Huilin; Wongkongkathep, Piriya; Van Orden, Steve L.; Ogorzalek Loo, Rachel R.; Loo, Joseph A.

    2014-12-01

    "Native" mass spectrometry (MS) has been proven to be increasingly useful for structural biology studies of macromolecular assemblies. Using horse liver alcohol dehydrogenase (hADH) and yeast alcohol dehydrogenase (yADH) as examples, we demonstrate that rich information can be obtained in a single native top-down MS experiment using Fourier transform ion cyclotron mass spectrometry (FTICR MS). Beyond measuring the molecular weights of the protein complexes, isotopic mass resolution was achieved for yeast ADH tetramer (147 kDa) with an average resolving power of 412,700 at m/z 5466 in absorption mode, and the mass reflects that each subunit binds to two zinc atoms. The N-terminal 89 amino acid residues were sequenced in a top-down electron capture dissociation (ECD) experiment, along with the identifications of the zinc binding site at Cys46 and a point mutation (V58T). With the combination of various activation/dissociation techniques, including ECD, in-source dissociation (ISD), collisionally activated dissociation (CAD), and infrared multiphoton dissociation (IRMPD), 40% of the yADH sequence was derived directly from the native tetramer complex. For hADH, native top-down ECD-MS shows that both E and S subunits are present in the hADH sample, with a relative ratio of 4:1. Native top-down ISD of the hADH dimer shows that each subunit (E and S chains) binds not only to two zinc atoms, but also the NAD/NADH ligand, with a higher NAD/NADH binding preference for the S chain relative to the E chain. In total, 32% sequence coverage was achieved for both E and S chains.

  2. A Comparison of Error Bounds for a Nonlinear Tracking System with Detection Probability Pd < 1

    Science.gov (United States)

    Tong, Huisi; Zhang, Hao; Meng, Huadong; Wang, Xiqin

    2012-01-01

    Error bounds for nonlinear filtering are very important for performance evaluation and sensor management. This paper presents a comparative study of three error bounds for tracking filtering, when the detection probability is less than unity. One of these bounds is the random finite set (RFS) bound, which is deduced within the framework of finite set statistics. The others, which are the information reduction factor (IRF) posterior Cramer-Rao lower bound (PCRLB) and enumeration method (ENUM) PCRLB are introduced within the framework of finite vector statistics. In this paper, we deduce two propositions and prove that the RFS bound is equal to the ENUM PCRLB, while it is tighter than the IRF PCRLB, when the target exists from the beginning to the end. Considering the disappearance of existing targets and the appearance of new targets, the RFS bound is tighter than both IRF PCRLB and ENUM PCRLB with time, by introducing the uncertainty of target existence. The theory is illustrated by two nonlinear tracking applications: ballistic object tracking and bearings-only tracking. The simulation studies confirm the theory and reveal the relationship among the three bounds. PMID:23242274

  3. The shock formation distance in a bounded sound beam of finite amplitude.

    Science.gov (United States)

    Tao, Chao; Ma, Jian; Zhu, Zhemin; Du, Gonghuan; Ping, Zihong

    2003-07-01

    This paper investigates the shock formation distance in a bounded sound beam of finite amplitude by solving the Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation using frequency-domain numerical method. Simulation results reveal that, besides the nonlinearity and absorption, the diffraction is another important factor that affects the shock formation of a bounded sound beam. More detailed discussions of the shock formation in a bounded sound beam, such as the waveform of sound pressure and the spatial distribution of shock formation, are also presented and compared for different parameters.

  4. Tight Bounds for Distributed Functional Monitoring

    DEFF Research Database (Denmark)

    Woodruff, David P.; Zhang, Qin

    2011-01-01

    $, our bound resolves their main open question. Our lower bounds are based on new direct sum theorems for approximate majority, and yield significant improvements to problems in the data stream model, improving the bound for estimating $F_p, p > 2,$ in $t$ passes from $\\tilde{\\Omega}(n^{1-2/p}/(\\eps^{2/p......} t))$ to $\\tilde{\\Omega}(n^{1-2/p}/(\\eps^{4/p} t))$, giving the first bound for estimating $F_0$ in $t$ passes of $\\Omega(1/(\\eps^2 t))$ bits of space that does not use the gap-hamming problem, and showing a distribution for the gap-hamming problem with high external information cost or super...

  5. Redshift-space limits of bound structures

    NARCIS (Netherlands)

    Duenner, Rolando; Reisenegger, Andreas; Meza, Andres; Araya, Pablo A.; Quintana, Hernan

    2007-01-01

    An exponentially expanding Universe, possibly governed by a cosmological constant, forces gravitationally bound structures to become more and more isolated, eventually becoming causally disconnected from each other and forming so-called 'island universes'. This new scenario reformulates the question

  6. Upper Bound for Neutron Emission from Sonoluminescing Bubbles in Deuterated Acetone

    International Nuclear Information System (INIS)

    Camara, C. G.; Putterman, S. J.; Hopkins, S. D.; Suslick, K. S.

    2007-01-01

    An experimental search for nuclear fusion inside imploding bubbles of degassed deuterated acetone at 0 degree sign C driven by a 15 atm sound field and seeded with a neutron generator reveals an upper bound that is a factor of 10 000 less than the signal reported by Taleyarkhan et al. The strength of our upper bound is limited by the weakness of sonoluminescence, which we ascribe to the relatively high vapor pressure of acetone

  7. Halloysite Nanotubes Noncovalently Functionalised with SDS Anionic Surfactant and PS-b-P4VP Block Copolymer for Their Effective Dispersion in Polystyrene as UV-Blocking Nanocomposite Films

    Directory of Open Access Journals (Sweden)

    Lazaros Tzounis

    2017-01-01

    Full Text Available A simple and versatile method is reported for the noncovalent functionalisation of natural and “green” halloysite nanotubes (HNTs allowing their effective dispersion in a polystyrene (PS thermoplastic matrix via solvent mixing. Initially, HNTs (pristine HNTs were modified with physically adsorbed surfactant molecules of sodium dodecyl sulphate (SDS and PS-b-P4VP [P4VP: poly(4-vinylpyridine] block copolymer (BCP. Hereafter, SDS and BCP modified HNTs will be indicated as SDS-m-HNT and BCP-m-HNT. Nanocomposite films with 1, 2, and 5 wt.% HNT loadings were prepared, abbreviated as PS-SDS-m-HNT1, PS-SDS-m-HNT2, and PS-SDS-m-HNT5 and PS-BCP-m-HNT1, PS-BCP-m-HNT2, and PS-BCP-m-HNT5 (where 1, 2, and 5 correspond to the wt.% of HNTs. All nanocomposites depicted improved thermal degradation compared to the neat PS as revealed by thermogravimetric analysis (TGA. Transmission electron microscopy (TEM confirmed the good dispersion state of HNTs and the importance of modification by SDS and BCP. X-ray diffraction (XRD studies showed the characteristic interlayer spacing between the two silicate layers of pristine and modified HNTs. The PS/HNT nanocomposite films exhibited excellent ultraviolent-visible (UV-vis absorbance properties and their potential application as UV-filters could be envisaged.

  8. Error Bounds: Necessary and Sufficient Conditions

    Czech Academy of Sciences Publication Activity Database

    Outrata, Jiří; Kruger, A.Y.; Fabian, Marián; Henrion, R.

    2010-01-01

    Roč. 18, č. 2 (2010), s. 121-149 ISSN 1877-0533 R&D Projects: GA AV ČR IAA100750802 Institutional research plan: CEZ:AV0Z10750506; CEZ:AV0Z10190503 Keywords : Error bounds * Calmness * Subdifferential * Slope Subject RIV: BA - General Mathematics Impact factor: 0.333, year: 2010 http://library.utia.cas.cz/separaty/2010/MTR/outrata-error bounds necessary and sufficient conditions.pdf

  9. Malabsorption of protein bound vitamin B12.

    OpenAIRE

    Dawson, D W; Sawers, A H; Sharma, R K

    1984-01-01

    Patients with subnormal serum vitamin B12 concentrations were tested for absorption of protein bound vitamin B12 and compared with controls. Absorption of the protein bound vitamin appeared to decrease with increasing age in healthy subjects. Differences between the result of this test and the result of the Schilling test in patients who had undergone gastric surgery were confirmed; such differences were also seen in some patients who had iron deficiency anaemia, an excessive alcohol intake, ...

  10. New Spectral Features from Bound Dark Matter

    DEFF Research Database (Denmark)

    Catena, Riccardo; Kouvaris, Chris

    2016-01-01

    We demonstrate that dark matter particles gravitationally bound to the Earth can induce a characteristic nuclear recoil signal at low energies in direct detection experiments. The new spectral feature we predict can provide the ultimate smoking gun for dark matter discovery for experiments...... with positive signal but unclear background. The new feature is universal, in that the ratio of bound over halo dark matter event rates at detectors is independent of the dark matter-nucleon cross section....

  11. Automatic bounding estimation in modified NLMS algorithm

    International Nuclear Information System (INIS)

    Shahtalebi, K.; Doost-Hoseini, A.M.

    2002-01-01

    Modified Normalized Least Mean Square algorithm, which is a sign form of Nlm based on set-membership (S M) theory in the class of optimal bounding ellipsoid (OBE) algorithms, requires a priori knowledge of error bounds that is unknown in most applications. In a special but popular case of measurement noise, a simple algorithm has been proposed. With some simulation examples the performance of algorithm is compared with Modified Normalized Least Mean Square

  12. Absolute Lower Bound on the Bounce Action

    Science.gov (United States)

    Sato, Ryosuke; Takimoto, Masahiro

    2018-03-01

    The decay rate of a false vacuum is determined by the minimal action solution of the tunneling field: bounce. In this Letter, we focus on models with scalar fields which have a canonical kinetic term in N (>2 ) dimensional Euclidean space, and derive an absolute lower bound on the bounce action. In the case of four-dimensional space, we show the bounce action is generically larger than 24 /λcr, where λcr≡max [-4 V (ϕ )/|ϕ |4] with the false vacuum being at ϕ =0 and V (0 )=0 . We derive this bound on the bounce action without solving the equation of motion explicitly. Our bound is derived by a quite simple discussion, and it provides useful information even if it is difficult to obtain the explicit form of the bounce solution. Our bound offers a sufficient condition for the stability of a false vacuum, and it is useful as a quick check on the vacuum stability for given models. Our bound can be applied to a broad class of scalar potential with any number of scalar fields. We also discuss a necessary condition for the bounce action taking a value close to this lower bound.

  13. Generalized surface tension bounds in vacuum decay

    Science.gov (United States)

    Masoumi, Ali; Paban, Sonia; Weinberg, Erick J.

    2018-02-01

    Coleman and De Luccia (CDL) showed that gravitational effects can prevent the decay by bubble nucleation of a Minkowski or AdS false vacuum. In their thin-wall approximation this happens whenever the surface tension in the bubble wall exceeds an upper bound proportional to the difference of the square roots of the true and false vacuum energy densities. Recently it was shown that there is another type of thin-wall regime that differs from that of CDL in that the radius of curvature grows substantially as one moves through the wall. Not only does the CDL derivation of the bound fail in this case, but also its very formulation becomes ambiguous because the surface tension is not well defined. We propose a definition of the surface tension and show that it obeys a bound similar in form to that of the CDL case. We then show that both thin-wall bounds are special cases of a more general bound that is satisfied for all bounce solutions with Minkowski or AdS false vacua. We discuss the limit where the parameters of the theory attain critical values and the bound is saturated. The bounce solution then disappears and a static planar domain wall solution appears in its stead. The scalar field potential then is of the form expected in supergravity, but this is only guaranteed along the trajectory in field space traced out by the bounce.

  14. Investigating the Non-Covalent Functionalization and Chemical Transformation of Graphene

    Science.gov (United States)

    Sham, Chun-Hong

    Trend in device miniatures demands capabilities to produce rationally designed patterns in ever-shrinking length scale. The research community has examined various techniques to push the current lithography resolution to sub-10nm scale. One of the ideas is to utilize the natural nanoscale patterns of molecular assemblies. In this thesis, the self-assembling phenomenon of a photoactive molecule on epitaxial graphene (EG) grown on SiC was discussed. This molecular assembly enables manipulation of chemical contrast in nanoscale through UV exposure or atomic layer deposition. Future development of nanoelectronics industry will be fueled by innovations in electronics materials, which could be discovered through covalent modification of graphene. In a study reported in this thesis, silicon is deposited onto EG. After annealing, a new surface reconstruction, identified to be (3x3)-SiC, was formed. Raman spectroscopy finds no signature of graphene after annealing, indicating a complete chemical transformation of graphene. DFT calculations reveal a possible conversion mechanism. Overall, these studies provide insights for future device miniaturization; contribute to the search of novel materials and help bridging the gap between graphene and current silicon-based industrial infrastructures.

  15. Properties of ammonium ion-water clusters: analyses of structure evolution, noncovalent interactions, and temperature and humidity effects.

    Science.gov (United States)

    Pei, Shi-Tu; Jiang, Shuai; Liu, Yi-Rong; Huang, Teng; Xu, Kang-Ming; Wen, Hui; Zhu, Yu-Peng; Huang, Wei

    2015-03-26

    Although ammonium ion-water clusters are abundant in the biosphere, some information regarding these clusters, such as their growth route, the influence of temperature and humidity, and the concentrations of various hydrated clusters, is lacking. In this study, theoretical calculations are performed on ammonium ion-water clusters. These theoretical calculations are focused on determining the following characteristics: (1) the pattern of cluster growth; (2) the percentages of clusters of the same size at different temperatures and humidities; (3) the distributions of different isomers for the same size clusters at different temperatures; (4) the relative strengths of the noncovalent interactions for clusters of different sizes. The results suggest that the dipole moment may be very significant for the ammonium ion-water system, and some new stable isomers were found. The nucleation of ammonium ions and water molecules is favorable at low temperatures; thus, the clusters observed at high altitudes might not be present at low altitudes. High humidity can contribute to the formation of large ammonium ion-water clusters, whereas the formation of small clusters may be favorable under low-humidity conditions. The potential energy surfaces (PES) of these different sized clusters are complicated and differ according to the distribution of isomers at different temperatures. Some similar structures are observed between NH4(+)(H2O)n and M(H2O)n (where M represents an alkali metal ion or water molecule); when n = 8, the clusters begin to form the closed-cage geometry. As the cluster size increases, these interactions become progressively weaker. The successive binding energy at the DF-MP2-F12/VDZ-F12 level is better than that at the PW91PW91/6-311++G(3df, 3pd) level and is consistent with the experimentally determined values.

  16. Quantum Mechanical Calculation of Noncovalent Interactions: A Large-Scale Evaluation of PMx, DFT, and SAPT Approaches.

    Science.gov (United States)

    Li, Amanda; Muddana, Hari S; Gilson, Michael K

    2014-04-08

    Quantum mechanical (QM) calculations of noncovalent interactions are uniquely useful as tools to test and improve molecular mechanics force fields and to model the forces involved in biomolecular binding and folding. Because the more computationally tractable QM methods necessarily include approximations, which risk degrading accuracy, it is essential to evaluate such methods by comparison with high-level reference calculations. Here, we use the extensive Benchmark Energy and Geometry Database (BEGDB) of CCSD(T)/CBS reference results to evaluate the accuracy and speed of widely used QM methods for over 1200 chemically varied gas-phase dimers. In particular, we study the semiempirical PM6 and PM7 methods; density functional theory (DFT) approaches B3LYP, B97-D, M062X, and ωB97X-D; and symmetry-adapted perturbation theory (SAPT) approach. For the PM6 and DFT methods, we also examine the effects of post hoc corrections for hydrogen bonding (PM6-DH+, PM6-DH2), halogen atoms (PM6-DH2X), and dispersion (DFT-D3 with zero and Becke-Johnson damping). Several orders of the SAPT expansion are also compared, ranging from SAPT0 up to SAPT2+3, where computationally feasible. We find that all DFT methods with dispersion corrections, as well as SAPT at orders above SAPT2, consistently provide dimer interaction energies within 1.0 kcal/mol RMSE across all systems. We also show that a linear scaling of the perturbative energy terms provided by the fast SAPT0 method yields similar high accuracy, at particularly low computational cost. The energies of all the dimer systems from the various QM approaches are included in the Supporting Information, as are the full SAPT2+(3) energy decomposition for a subset of over 1000 systems. The latter can be used to guide the parametrization of molecular mechanics force fields on a term-by-term basis.

  17. A pH-responsive wormlike micellar system of a noncovalent interaction-based surfactant with a tunable molecular structure.

    Science.gov (United States)

    Kang, Wanli; Wang, Pengxiang; Fan, Haiming; Yang, Hongbin; Dai, Caili; Yin, Xia; Zhao, Yilu; Guo, Shujun

    2017-02-08

    Responsive wormlike micelles are very useful in a number of applications, whereas it is still challenging to create dramatic viscosity changes in wormlike micellar systems. Here we developed a pH-responsive wormlike micellar system based on a noncovalent constructed surfactant, which is formed by the complexation of N-erucamidopropyl-N,N-dimethylamine (UC 22 AMPM) and citric acid at the molar ratio of 3 : 1 (EACA). The phase behavior, aggregate microstructure and viscoelasticity of EACA solutions were investigated by macroscopic appearance observation, rheological and cryo-TEM measurements. It was found that the phase behavior of EACA solutions undergoes transition from transparent viscoelastic fluids to opalescent solutions and then phase separation with white floaters upon increasing the pH. Upon increasing the pH from 2.03 to 6.17, the viscosity of wormlike micelles in the transparent solutions continuously increased and reached ∼683 000 mPa s at pH 6.17. As the pH was adjusted to 7.31, the opalescent solution shows a water-like flowing behaviour and the η 0 rapidly declines to ∼1 mPa s. Thus, dramatic viscosity changes of about 6 magnitudes can be triggered by varying the pH values without any deterioration of the EACA system. This drastic variation in rheological behavior is attributed to the pH dependent interaction between UC 22 AMPM and citric acid. Furthermore, the dependence on concentration and temperature of the rheological behavior of EACA solutions was also studied to assist in obtaining the desired pH-responsive viscosity changes.

  18. Non-covalent interactions across organic and biological subsets of chemical space: Physics-based potentials parametrized from machine learning

    Science.gov (United States)

    Bereau, Tristan; DiStasio, Robert A.; Tkatchenko, Alexandre; von Lilienfeld, O. Anatole

    2018-06-01

    Classical intermolecular potentials typically require an extensive parametrization procedure for any new compound considered. To do away with prior parametrization, we propose a combination of physics-based potentials with machine learning (ML), coined IPML, which is transferable across small neutral organic and biologically relevant molecules. ML models provide on-the-fly predictions for environment-dependent local atomic properties: electrostatic multipole coefficients (significant error reduction compared to previously reported), the population and decay rate of valence atomic densities, and polarizabilities across conformations and chemical compositions of H, C, N, and O atoms. These parameters enable accurate calculations of intermolecular contributions—electrostatics, charge penetration, repulsion, induction/polarization, and many-body dispersion. Unlike other potentials, this model is transferable in its ability to handle new molecules and conformations without explicit prior parametrization: All local atomic properties are predicted from ML, leaving only eight global parameters—optimized once and for all across compounds. We validate IPML on various gas-phase dimers at and away from equilibrium separation, where we obtain mean absolute errors between 0.4 and 0.7 kcal/mol for several chemically and conformationally diverse datasets representative of non-covalent interactions in biologically relevant molecules. We further focus on hydrogen-bonded complexes—essential but challenging due to their directional nature—where datasets of DNA base pairs and amino acids yield an extremely encouraging 1.4 kcal/mol error. Finally, and as a first look, we consider IPML for denser systems: water clusters, supramolecular host-guest complexes, and the benzene crystal.

  19. Photodissociative Cross-Linking of Non-covalent Peptide-Peptide Ion Complexes in the Gas Phase

    Science.gov (United States)

    Nguyen, Huong T. H.; Andrikopoulos, Prokopis C.; Rulíšek, Lubomír; Shaffer, Christopher J.; Tureček, František

    2018-05-01

    We report a gas-phase UV photodissociation study investigating non-covalent interactions between neutral hydrophobic pentapeptides and peptide ions incorporating a diazirine-tagged photoleucine residue. Phenylalanine (Phe) and proline (Pro) were chosen as the conformation-affecting residues that were incorporated into a small library of neutral pentapeptides. Gas-phase ion-molecule complexes of these peptides with photo-labeled pentapeptides were subjected to photodissociation. Selective photocleavage of the diazirine ring at 355 nm formed short-lived carbene intermediates that underwent cross-linking by insertion into H-X bonds of the target peptide. The cross-link positions were established from collision-induced dissociation tandem mass spectra (CID-MS3) providing sequence information on the covalent adducts. Effects of the amino acid residue (Pro or Phe) and its position in the target peptide sequence were evaluated. For proline-containing peptides, interactions resulting in covalent cross-links in these complexes became more prominent as proline was moved towards the C-terminus of the target peptide sequence. The photocross-linking yields of phenylalanine-containing peptides depended on the position of both phenylalanine and photoleucine. Density functional theory calculations were used to assign structures of low-energy conformers of the (GLPMG + GLL*LK + H)+ complex. Born-Oppenheimer molecular dynamics trajectory calculations were used to capture the thermal motion in the complexes within 100 ps and determine close contacts between the incipient carbene and the H-X bonds in the target peptide. This provided atomic-level resolution of potential cross-links that aided spectra interpretation and was in agreement with experimental data. [Figure not available: see fulltext.

  20. Modulation of the genotoxicity of bleomycin by amines through noncovalent DNA interactions and alteration of physiological conditions in yeast

    International Nuclear Information System (INIS)

    Hoffmann, George R.; Gessner, Gabrielle S.; Hughes, Jennifer F.; Ronan, Matthew V.; Sylvia, Katelyn E.; Willett, Christine J.

    2007-01-01

    noncovalent association with DNA, altered BLM access to DNA, and modulation of physiological conditions

  1. Modulation of the genotoxicity of bleomycin by amines through noncovalent DNA interactions and alteration of physiological conditions in yeast

    Energy Technology Data Exchange (ETDEWEB)

    Hoffmann, George R. [Department of Biology, College of the Holy Cross, One College Street, Worcester, MA 01610-2395 (United States)], E-mail: ghoffmann@holycross.edu; Gessner, Gabrielle S.; Hughes, Jennifer F.; Ronan, Matthew V.; Sylvia, Katelyn E.; Willett, Christine J. [Department of Biology, College of the Holy Cross, One College Street, Worcester, MA 01610-2395 (United States)

    2007-10-01

    noncovalent association with DNA, altered BLM access to DNA, and modulation of physiological conditions.

  2. Ultrasensitive Nanoimmunosensor by coupling non-covalent functionalized graphene oxide platform and numerous ferritin labels on carbon nanotubes.

    Science.gov (United States)

    Akter, Rashida; Jeong, Bongjin; Choi, Jong-Soon; Rahman, Md Aminur

    2016-06-15

    An ultrasensitive electrochemical nanostructured immunosensor for a breast cancer biomarker carbohydrate antigen 15-3 (CA 15-3) was fabricated using non-covalent functionalized graphene oxides (GO/Py-COOH) as sensor probe and multiwalled carbon nanotube (MWCNTs)-supported numerous ferritin as labels. The immunosensor was constructed by immobilizing a monoclonal anti-CA 15-3 antibody on the GO modified cysteamine (Cys) self-assembled monolayer (SAM) on an Au electrode (Au/Cys) through the amide bond formation between the carboxylic acid groups of GO/Py-COOH and amine groups of anti-CA 15-3. Secondary antibody conjugated MWCNT-supported ferritin labels (Ab2-MWCNT-Ferritin) were prepared through the amide bond formation between amine groups of Ab2 and ferritin and carboxylic acid groups of MWCNTs. The detection of CA 15-3 was based on the enhanced bioelectrocatalytic reduction of hydrogen peroxide mediated by hydroquinone (HQ) at the GO/Py-COOH-based sensor probe. The GO/Py-COOH-based sensor probe and Ab2-MWCNT-Ferritin labels were characterized using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM), transmission electron microscope (TEM), and x-ray photoelectron spectroscopy (XPS) techniques. Using differential pulse voltammetry (DPV) technique, CA 15-3 can be selectively detected as low as 0.01 ± 0.07 U/mL in human serum samples. Additionally, the proposed CA 15-3 immunosensor showed excellent selectivity and better stability in human serum samples, which demonstrated that the proposed immunosensor has potentials in proteomic researches and diagnostics. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Mathematics revealed

    CERN Document Server

    Berman, Elizabeth

    1979-01-01

    Mathematics Revealed focuses on the principles, processes, operations, and exercises in mathematics.The book first offers information on whole numbers, fractions, and decimals and percents. Discussions focus on measuring length, percent, decimals, numbers as products, addition and subtraction of fractions, mixed numbers and ratios, division of fractions, addition, subtraction, multiplication, and division. The text then examines positive and negative numbers and powers and computation. Topics include division and averages, multiplication, ratios, and measurements, scientific notation and estim

  4. The ultimate security bounds of quantum key distribution protocols

    International Nuclear Information System (INIS)

    Nikolopoulos, G.M.; Alber, G.

    2005-01-01

    Full text: Quantum key distribution (QKD) protocols exploit quantum correlations in order to establish a secure key between two legitimate users. Recent work on QKD has revealed a remarkable link between quantum and secret correlations. In this talk we report on recent results concerning the ultimate upper security bounds of various QKD schemes (i.e., the maximal disturbance up to which the two legitimate users share quantum correlations) under the assumption of general coherent attacks. In particular, we derive an analytic expression for the ultimate upper security bound of QKD schemes that use two mutually unbiased bases. As long as the two legitimate users focus on the sifted key and treat each pair of data independently during the post processing, our results are valid for arbitrary dimensions of the information carriers. The bound we have derived is well below the predictions of optimal cloning machines. The possibility of extraction of a secret key beyond entanglement distillation is also discussed. In the case of qutrits we argue that any eavesdropping strategy is equivalent to a symmetric one. For higher dimensions, however, such equivalence is generally no longer valid. (author)

  5. Exploring the "intensity fading" phenomenon in the study of noncovalent interactions by MALDI-TOF mass spectrometry

    DEFF Research Database (Denmark)

    Yanes, Oscar; Aviles, Francesc X; Roepstorff, Peter

    2007-01-01

    the intensity fading phenomenon, as well as a comparison with the strategy based on the direct detection of intact complexes by MALDI MS. For this purpose, the study is focused on two different protease-inhibitor complexes naturally occurring in solution, together with a heterogeneous mixture of nonbinding...... molecules derived from a biological extract, to examine the specificity of the approach, i.e., those of carboxypeptidase A (CPA) bound to potato carboxypeptidase inhibitor (PCI) and of trypsin bound to bovine pancreatic trypsin inhibitor (BPTI). Our results show that the intensity fading phenomenon occurs...

  6. Upper bounds on superpartner masses from upper bounds on the Higgs boson mass.

    Science.gov (United States)

    Cabrera, M E; Casas, J A; Delgado, A

    2012-01-13

    The LHC is putting bounds on the Higgs boson mass. In this Letter we use those bounds to constrain the minimal supersymmetric standard model (MSSM) parameter space using the fact that, in supersymmetry, the Higgs mass is a function of the masses of sparticles, and therefore an upper bound on the Higgs mass translates into an upper bound for the masses for superpartners. We show that, although current bounds do not constrain the MSSM parameter space from above, once the Higgs mass bound improves big regions of this parameter space will be excluded, putting upper bounds on supersymmetry (SUSY) masses. On the other hand, for the case of split-SUSY we show that, for moderate or large tanβ, the present bounds on the Higgs mass imply that the common mass for scalars cannot be greater than 10(11)  GeV. We show how these bounds will evolve as LHC continues to improve the limits on the Higgs mass.

  7. Far-Infrared Spectroscopy of Weakly Bound Hydrated Cluster Molecules

    DEFF Research Database (Denmark)

    Andersen, Jonas

    The thermodynamic properties of condensed phases, the functionality of many materials and the molecular organization in biological organisms are all governed by the classes of non-covalent interactions that occur already on the microscopic scale between pairs of molecules. A detailed investigation...... of the intermolecular interactions between prototypical molecular assemblies are valuable for accurate descriptions of larger supramolecular systems such as materials, gas hydrates and biological macromolecules. The aim of this PhD dissertation is to investigate intermolecular interactions fora series of medium...... vibrational bands of the cluster molecules in the challenging far-infrared and terahertz spectral regions.A key parameter in the validation of the performance of theoretical predictions for weak non-covalent intermolecular interactions is the dissociation energy D0 that depends heavily on the class of large...

  8. Bounds on poloidal kinetic energy in plane layer convection

    Science.gov (United States)

    Tilgner, A.

    2017-12-01

    A numerical method is presented that conveniently computes upper bounds on heat transport and poloidal energy in plane layer convection for infinite and finite Prandtl numbers. The bounds obtained for the heat transport coincide with earlier results. These bounds imply upper bounds for the poloidal energy, which follow directly from the definitions of dissipation and energy. The same constraints used for computing upper bounds on the heat transport lead to improved bounds for the poloidal energy.

  9. Bounds for nonlinear composites via iterated homogenization

    Science.gov (United States)

    Ponte Castañeda, P.

    2012-09-01

    Improved estimates of the Hashin-Shtrikman-Willis type are generated for the class of nonlinear composites consisting of two well-ordered, isotropic phases distributed randomly with prescribed two-point correlations, as determined by the H-measure of the microstructure. For this purpose, a novel strategy for generating bounds has been developed utilizing iterated homogenization. The general idea is to make use of bounds that may be available for composite materials in the limit when the concentration of one of the phases (say phase 1) is small. It then follows from the theory of iterated homogenization that it is possible, under certain conditions, to obtain bounds for more general values of the concentration, by gradually adding small amounts of phase 1 in incremental fashion, and sequentially using the available dilute-concentration estimate, up to the final (finite) value of the concentration (of phase 1). Such an approach can also be useful when available bounds are expected to be tighter for certain ranges of the phase volume fractions. This is the case, for example, for the "linear comparison" bounds for porous viscoplastic materials, which are known to be comparatively tighter for large values of the porosity. In this case, the new bounds obtained by the above-mentioned "iterated" procedure can be shown to be much improved relative to the earlier "linear comparison" bounds, especially at low values of the porosity and high triaxialities. Consistent with the way in which they have been derived, the new estimates are, strictly, bounds only for the class of multi-scale, nonlinear composites consisting of two well-ordered, isotropic phases that are distributed with prescribed H-measure at each stage in the incremental process. However, given the facts that the H-measure of the sequential microstructures is conserved (so that the final microstructures can be shown to have the same H-measure), and that H-measures are insensitive to length scales, it is conjectured

  10. Functions that Protect Escherichia coli from Tightly Bound DNA-Protein Complexes Created by Mutant EcoRII Methyltransferase.

    Science.gov (United States)

    Henderson, Morgan L; Kreuzer, Kenneth N

    2015-01-01

    Expression of mutant EcoRII methyltransferase protein (M.EcoRII-C186A) in Escherichia coli leads to tightly bound DNA-protein complexes (TBCs), located sporadically on the chromosome rather than in tandem arrays. The mechanisms behind the lethality induced by such sporadic TBCs are not well studied, nor is it clear whether very tight binding but non-covalent complexes are processed in the same way as covalent DNA-protein crosslinks (DPCs). Using 2D gel electrophoresis, we found that TBCs induced by M.EcoRII-C186A block replication forks in vivo. Specific bubble molecules were detected as spots on the 2D gel, only when M.EcoRII-C186A was induced, and a mutation that eliminates a specific EcoRII methylation site led to disappearance of the corresponding spot. We also performed a candidate gene screen for mutants that are hypersensitive to TBCs induced by M.EcoRII-C186A. We found several gene products necessary for protection against these TBCs that are known to also protect against DPCs induced with wild-type M.EcoRII (after 5-azacytidine incorporation): RecA, RecBC, RecG, RuvABC, UvrD, FtsK, XerCD and SsrA (tmRNA). In contrast, the RecFOR pathway and Rep helicase are needed for protection against TBCs but not DPCs induced by M.EcoRII. We propose that stalled fork processing by RecFOR and RecA promotes release of tightly bound (but non-covalent) blocking proteins, perhaps by licensing Rep helicase-driven dissociation of the blocking M.EcoRII-C186A. Our studies also argued against the involvement of several proteins that might be expected to protect against TBCs. We took the opportunity to directly compare the sensitivity of all tested mutants to two quinolone antibiotics, which target bacterial type II topoisomerases and induce a unique form of DPC. We uncovered rep, ftsK and xerCD as novel quinolone hypersensitive mutants, and also obtained evidence against the involvement of a number of functions that might be expected to protect against quinolones.

  11. Functions that Protect Escherichia coli from Tightly Bound DNA-Protein Complexes Created by Mutant EcoRII Methyltransferase.

    Directory of Open Access Journals (Sweden)

    Morgan L Henderson

    Full Text Available Expression of mutant EcoRII methyltransferase protein (M.EcoRII-C186A in Escherichia coli leads to tightly bound DNA-protein complexes (TBCs, located sporadically on the chromosome rather than in tandem arrays. The mechanisms behind the lethality induced by such sporadic TBCs are not well studied, nor is it clear whether very tight binding but non-covalent complexes are processed in the same way as covalent DNA-protein crosslinks (DPCs. Using 2D gel electrophoresis, we found that TBCs induced by M.EcoRII-C186A block replication forks in vivo. Specific bubble molecules were detected as spots on the 2D gel, only when M.EcoRII-C186A was induced, and a mutation that eliminates a specific EcoRII methylation site led to disappearance of the corresponding spot. We also performed a candidate gene screen for mutants that are hypersensitive to TBCs induced by M.EcoRII-C186A. We found several gene products necessary for protection against these TBCs that are known to also protect against DPCs induced with wild-type M.EcoRII (after 5-azacytidine incorporation: RecA, RecBC, RecG, RuvABC, UvrD, FtsK, XerCD and SsrA (tmRNA. In contrast, the RecFOR pathway and Rep helicase are needed for protection against TBCs but not DPCs induced by M.EcoRII. We propose that stalled fork processing by RecFOR and RecA promotes release of tightly bound (but non-covalent blocking proteins, perhaps by licensing Rep helicase-driven dissociation of the blocking M.EcoRII-C186A. Our studies also argued against the involvement of several proteins that might be expected to protect against TBCs. We took the opportunity to directly compare the sensitivity of all tested mutants to two quinolone antibiotics, which target bacterial type II topoisomerases and induce a unique form of DPC. We uncovered rep, ftsK and xerCD as novel quinolone hypersensitive mutants, and also obtained evidence against the involvement of a number of functions that might be expected to protect against quinolones.

  12. Thermalization Time Bounds for Pauli Stabilizer Hamiltonians

    Science.gov (United States)

    Temme, Kristan

    2017-03-01

    We prove a general lower bound to the spectral gap of the Davies generator for Hamiltonians that can be written as the sum of commuting Pauli operators. These Hamiltonians, defined on the Hilbert space of N-qubits, serve as one of the most frequently considered candidates for a self-correcting quantum memory. A spectral gap bound on the Davies generator establishes an upper limit on the life time of such a quantum memory and can be used to estimate the time until the system relaxes to thermal equilibrium when brought into contact with a thermal heat bath. The bound can be shown to behave as {λ ≥ O(N^{-1} exp(-2β overline{ɛ}))}, where {overline{ɛ}} is a generalization of the well known energy barrier for logical operators. Particularly in the low temperature regime we expect this bound to provide the correct asymptotic scaling of the gap with the system size up to a factor of N -1. Furthermore, we discuss conditions and provide scenarios where this factor can be removed and a constant lower bound can be proven.

  13. Universal bounds in even-spin CFTs

    Energy Technology Data Exchange (ETDEWEB)

    Qualls, Joshua D. [Department of Physics, National Taiwan University,Taipei, Taiwan (China)

    2015-12-01

    We prove using invariance under the modular S− and ST−transformations that every unitary two-dimensional conformal field theory (CFT) having only even-spin primary operators (with no extended chiral algebra and with right- and left-central charges c,c̃>1) contains a primary operator with dimension Δ{sub 1} satisfying 0<Δ{sub 1}<((c+c̃)/24)+0.09280…. After deriving both analytical and numerical bounds, we discuss how to extend our methods to bound higher conformal dimensions before deriving lower and upper bounds on the number of primary operators in a given energy range. Using the AdS{sub 3}/CFT{sub 2} dictionary, the bound on Δ{sub 1} proves the lightest massive excitation in appropriate theories of 3D matter and gravity with cosmological constant Λ<0 can be no heavier than 1/8G{sub N}+O(√(−Λ)); the bounds on the number of operators are related via AdS/CFT to the entropy of states in the dual gravitational theory. In the flat-space approximation, the limiting mass is exactly that of the lightest BTZ black hole.

  14. Targeted drug delivery with polymers and magnetic nanoparticles: covalent and noncovalent approaches, release control, and clinical studies

    Czech Academy of Sciences Publication Activity Database

    Ulbrich, Karel; Holá, K.; Šubr, Vladimír; Bakandritsos, A.; Tuček, J.; Zbořil, R.

    2016-01-01

    Roč. 116, č. 9 (2016), s. 5338-5431 ISSN 0009-2665 R&D Projects: GA ČR(CZ) GAP301/12/1254 Institutional support: RVO:61389013 Keywords : iron-oxide nanoparticles * cell lung-cancer * copolymer-bound doxorubicin Subject RIV: CD - Macromolecular Chemistry Impact factor: 47.928, year: 2016

  15. Yukawa Bound States and Their LHC Phenomenology

    Directory of Open Access Journals (Sweden)

    Enkhbat Tsedenbaljir

    2013-01-01

    Full Text Available We present the current status on the possible bound states of extra generation quarks. These include phenomenology and search strategy at the LHC. If chiral fourth-generation quarks do exist their strong Yukawa couplings, implied by current experimental lower bound on their masses, may lead to formation of bound states. Due to nearly degenerate 4G masses suggested by Precision Electroweak Test one can employ “heavy isospin” symmetry to classify possible spectrum. Among these states, the color-octet isosinglet vector ω 8 is the easiest to be produced at the LHC. The discovery potential and corresponding decay channels are covered in this paper. With possible light Higgs at ~125 GeV two-Higgs doublet version is briefly discussed.

  16. Bounded Gaps between Products of Special Primes

    Directory of Open Access Journals (Sweden)

    Ping Ngai Chung

    2014-03-01

    Full Text Available In their breakthrough paper in 2006, Goldston, Graham, Pintz and Yıldırım proved several results about bounded gaps between products of two distinct primes. Frank Thorne expanded on this result, proving bounded gaps in the set of square-free numbers with r prime factors for any r ≥ 2, all of which are in a given set of primes. His results yield applications to the divisibility of class numbers and the triviality of ranks of elliptic curves. In this paper, we relax the condition on the number of prime factors and prove an analogous result using a modified approach. We then revisit Thorne’s applications and give a better bound in each case.

  17. Braneworld black holes and entropy bounds

    Directory of Open Access Journals (Sweden)

    Y. Heydarzade

    2018-01-01

    Full Text Available The Bousso's D-bound entropy for the various possible black hole solutions on a 4-dimensional brane is checked. It is found that the D-bound entropy here is apparently different from that of obtained for the 4-dimensional black hole solutions. This difference is interpreted as the extra loss of information, associated to the extra dimension, when an extra-dimensional black hole is moved outward the observer's cosmological horizon. Also, it is discussed that N-bound entropy is hold for the possible solutions here. Finally, by adopting the recent Bohr-like approach to black hole quantum physics for the excited black holes, the obtained results are written also in terms of the black hole excited states.

  18. Energy conditions bounds and supernovae data

    International Nuclear Information System (INIS)

    Lima, M.P.; Vitenti, S.D.P.; Reboucas, M.J.

    2008-01-01

    The energy conditions play an important role in the description of some important properties of the Universe, including the current accelerating expansion phase and the possible recent phase of super-acceleration. In a recent work we have provided a detailed study of the energy conditions for the recent past by deriving bounds from energy conditions and by making the confrontation of the bounds with supernovae data. Here, we extend and update these results in two different ways. First, by carrying out a new statistical analysis for q(z) estimates needed for the confrontation between the bounds and supernovae data. Second, by providing a new picture of the energy conditions fulfillment and violation in the light of the recently compiled Union set of 307 type Ia supernovae and by using two different statistical approaches

  19. Bound water in Kevlar 49 fibers

    International Nuclear Information System (INIS)

    Garza, R.G.; Pruneda, C.O.; Morgan, R.J.

    1981-01-01

    From elemental analyses, thermogravimetric-mass spectroscopy studies and re-evaluation of previous water diffusion studies in Kevlar 49 fibers it is concluded that these fibers can contain two types of sorbed moisture. The fibers can absorb up to approx. 6 wt % loosely bound water with an activation energy for outgassing by desorption of 6 kcal/mole. This loosely bound water is a direct result of the presence of Na 2 SO 4 impurities and the perturbations they induce on the packing of the rod-like poly (p-phenylene terephthalamide) macromolecules. Kevlar 49 fibers also inherently contain up to 30 wt % additional water which is tightly bound within the crystal lattice. This water exhibits an activation energy for outgassing by diffusion of approx. 40 kcal/mole and is only evolved from the fiber in significant quantities at t > 350 0 C over a period of hours

  20. Cosmological implications of Dark Matter bound states

    Energy Technology Data Exchange (ETDEWEB)

    Mitridate, Andrea [Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126, Pisa (Italy); Redi, Michele; Smirnov, Juri [INFN, Sezione di Firenze, and Dipartimento di Fisica e Astronomia, Università di Firenze, Via G. Sansone 1, 50019 Sesto Fiorentino (Italy); Strumia, Alessandro, E-mail: andrea.mitridate@gmail.com, E-mail: michele.redi@fi.infn.it, E-mail: juri.smirnov@mpi-hd.mpg.de, E-mail: alessandro.strumia@cern.ch [Dipartimento di Fisica dell' Università di Pisa and INFN, Pisa (Italy)

    2017-05-01

    We present generic formulæ for computing how Sommerfeld corrections together with bound-state formation affects the thermal abundance of Dark Matter with non-abelian gauge interactions. We consider DM as a fermion 3plet (wino) or 5plet under SU(2) {sub L} . In the latter case bound states raise to 11.5 TeV the DM mass required to reproduce the cosmological DM abundance and give indirect detection signals such as (for this mass) a dominant γ-line around 70 GeV. Furthermore, we consider DM co-annihilating with a colored particle, such as a squark or a gluino, finding that bound state effects are especially relevant in the latter case.

  1. Culture-Bound Words of the Danube Basin Countries: Translation into English

    Directory of Open Access Journals (Sweden)

    Chetverikova Olena

    2015-08-01

    Full Text Available Any course in linguistic country study or popular text translation is impossible without adequate understanding and presentation of culture-bound elements, which present one of the most difficult topics to deal with, especially in multicultural countries. Our investigation aims to show the problems, which appear when we deal with equivalent-lacking words related to culture. Sometimes equivalent-lacking words are associated with culture-bound words, the Ukrainian equivalent for them is “реалії” (derived from Latin realis, pl. realia. However, the term “culture-bound word” is of narrower meaning than the term “equivalent-lacking word”. A culture-bound word names an object peculiar to this or that ethnic culture. Equivalent-lacking words include, along with culture-bound words, neologisms, i.e. newly coined forms, dialect words, slang, taboo-words, foreign (third language terms, proper names, misspellings, archaisms. Comparison of languages and cultures reveals the various types of culture-bound words. Reasons for using them can be extralinguistic, lexical or stylistic. When translating culture-bound words a translator should be aware of the receptor’s potential problems, take into account his background knowledge and choose the best means of translation.

  2. Comparison of Lasserre's Measure-based Bounds for Polynomial Optimization to Bounds Obtained by Simulated Annealing

    NARCIS (Netherlands)

    de Klerk, Etienne; Laurent, Monique

    We consider the problem of minimizing a continuous function f over a compact set K. We compare the hierarchy of upper bounds proposed by Lasserre in [SIAM J. Optim. 21(3) (2011), pp. 864-885] to bounds that may be obtained from simulated annealing. We show that, when f is a polynomial and K a convex

  3. Career Development and Personal Functioning Differences between Work-Bound and Non-Work Bound Students

    Science.gov (United States)

    Creed, Peter A.; Patton, Wendy; Hood, Michelle

    2010-01-01

    We surveyed 506 Australian high school students on career development (exploration, planning, job-knowledge, decision-making, indecision), personal functioning (well-being, self-esteem, life satisfaction, school satisfaction) and control variables (parent education, school achievement), and tested differences among work-bound, college-bound and…

  4. A note on BPS vortex bound states

    Directory of Open Access Journals (Sweden)

    A. Alonso-Izquierdo

    2016-02-01

    Full Text Available In this note we investigate bound states, where scalar and vector bosons are trapped by BPS vortices in the Abelian Higgs model with a critical ratio of the couplings. A class of internal modes of fluctuation around cylindrically symmetric BPS vortices is characterized mathematically, analyzing the spectrum of the second-order fluctuation operator when the Higgs and vector boson masses are equal. A few of these bound states with low values of quantized magnetic flux are described fully, and their main properties are discussed.

  5. A note on BPS vortex bound states

    Energy Technology Data Exchange (ETDEWEB)

    Alonso-Izquierdo, A., E-mail: alonsoiz@usal.es [Departamento de Matematica Aplicada, Universidad de Salamanca (Spain); Garcia Fuertes, W., E-mail: wifredo@uniovi.es [Departamento de Fisica, Universidad de Oviedo (Spain); Mateos Guilarte, J., E-mail: guilarte@usal.es [Departamento de Fisica Fundamental, Universidad de Salamanca (Spain)

    2016-02-10

    In this note we investigate bound states, where scalar and vector bosons are trapped by BPS vortices in the Abelian Higgs model with a critical ratio of the couplings. A class of internal modes of fluctuation around cylindrically symmetric BPS vortices is characterized mathematically, analyzing the spectrum of the second-order fluctuation operator when the Higgs and vector boson masses are equal. A few of these bound states with low values of quantized magnetic flux are described fully, and their main properties are discussed.

  6. [Membrane-bound cytokine and feedforward regulation].

    Science.gov (United States)

    Wu, Ke-Fu; Zheng, Guo-Guang; Ma, Xiao-Tong; Song, Yu-Hua

    2013-10-01

    Feedback and feedforward widely exist in life system, both of them are the basic processes of control system. While the concept of feedback has been widely used in life science, feedforward regulation was systematically studied in neurophysiology, awaiting further evidence and mechanism in molecular biology and cell biology. The authors put forward a hypothesis about the feedforward regulation of membrane bound macrophage colony stimulation factor (mM-CSF) on the basis of their previous work. This hypothesis might provide a new direction for the study on the biological effects of mM-CSF on leukemia and solid tumors, and contribute to the study on other membrane bound cytokines.

  7. The covariant entropy bound in gravitational collapse

    International Nuclear Information System (INIS)

    Gao, Sijie; Lemos, Jose P. S.

    2004-01-01

    We study the covariant entropy bound in the context of gravitational collapse. First, we discuss critically the heuristic arguments advanced by Bousso. Then we solve the problem through an exact model: a Tolman-Bondi dust shell collapsing into a Schwarzschild black hole. After the collapse, a new black hole with a larger mass is formed. The horizon, L, of the old black hole then terminates at the singularity. We show that the entropy crossing L does not exceed a quarter of the area of the old horizon. Therefore, the covariant entropy bound is satisfied in this process. (author)

  8. Bound states in curved quantum waveguides

    International Nuclear Information System (INIS)

    Exner, P.; Seba, P.

    1987-01-01

    We study free quantum particle living on a curved planar strip Ω of a fixed width d with Dirichlet boundary conditions. It can serve as a model for electrons in thin films on a cylindrical-type substrate, or in a curved quantum wire. Assuming that the boundary of Ω is infinitely smooth and its curvature decays fast enough at infinity, we prove that a bound state with energy below the first transversal mode exists for all sufficiently small d. A lower bound on the critical width is obtained using the Birman-Schwinger technique. (orig.)

  9. Lower Bounds for External Memory Dictionaries

    DEFF Research Database (Denmark)

    Brodal, Gerth Stølting; Fagerberg, Rolf

    2003-01-01

    We study trade-offs between the update time and the query time for comparison based external memory dictionaries. The main contributions of this paper are two lower bound trade offs between the I/O complexity of member queries and insertions: If N < M insertions perform at most δ · N/B I/Os, then......We study trade-offs between the update time and the query time for comparison based external memory dictionaries. The main contributions of this paper are two lower bound trade offs between the I/O complexity of member queries and insertions: If N

  10. Finding Maximal Pairs with Bounded Gap

    DEFF Research Database (Denmark)

    Brodal, Gerth Stølting; Lyngsø, Rune B.; Pedersen, Christian N. S.

    1999-01-01

    . In this paper we present methods for finding all maximal pairs under various constraints on the gap. In a string of length n we can find all maximal pairs with gap in an upper and lower bounded interval in time O(n log n+z) where z is the number of reported pairs. If the upper bound is removed the time reduces...... to O(n+z). Since a tandem repeat is a pair where the gap is zero, our methods can be seen as a generalization of finding tandem repeats. The running time of our methods equals the running time of well known methods for finding tandem repeats....

  11. Bound constrained quadratic programming via piecewise

    DEFF Research Database (Denmark)

    Madsen, Kaj; Nielsen, Hans Bruun; Pinar, M. C.

    1999-01-01

    of a symmetric, positive definite matrix, and is solved by Newton iteration with line search. The paper describes the algorithm and its implementation including estimation of lambda/sub 1/ , how to get a good starting point for the iteration, and up- and downdating of Cholesky factorization. Results of extensive......We consider the strictly convex quadratic programming problem with bounded variables. A dual problem is derived using Lagrange duality. The dual problem is the minimization of an unconstrained, piecewise quadratic function. It involves a lower bound of lambda/sub 1/ , the smallest eigenvalue...

  12. Quantum Kolmogorov complexity and bounded quantum memory

    International Nuclear Information System (INIS)

    Miyadera, Takayuki

    2011-01-01

    The effect of bounded quantum memory in a primitive information protocol has been examined using the quantum Kolmogorov complexity as a measure of information. We employed a toy two-party protocol in which Bob, by using a bounded quantum memory and an unbounded classical memory, estimates a message that was encoded in qubits by Alice in one of the bases X or Z. Our theorem gave a nontrivial effect of the memory boundedness. In addition, a generalization of the uncertainty principle in the presence of quantum memory has been obtained.

  13. Collision-induced dissociation of noncovalent complexes between vancomycin antibiotics and peptide ligand stereoisomers: evidence for molecular recognition in the gas phase

    DEFF Research Database (Denmark)

    Jørgensen, Thomas J. D.; Delforge, D; Remacle, J

    1999-01-01

    In solution, the antibiotics of the vancomycin group bind stereospecifically to peptides with the C-terminal sequence: -L-Lys-D-Ala-D-Ala, Substitution by a L-Ala at either of the two C-terminal residues causes a dramatic decrease in the binding affinity to the antibiotics. This solution behavior...... is clearly reflected in electrospray ionization (ESI) mass spectra obtained from equimolar mixtures of an antibiotic, an isotopically labelled peptide ligand and an unlabelled peptide stereoisomer. Using collision-induced dissociation (CID) we have probed the gas phase stability of isomeric (1:1) noncovalent...

  14. Revealing Rembrandt

    Directory of Open Access Journals (Sweden)

    Andrew J Parker

    2014-04-01

    Full Text Available The power and significance of artwork in shaping human cognition is self-evident. The starting point for our empirical investigations is the view that the task of neuroscience is to integrate itself with other forms of knowledge, rather than to seek to supplant them. In our recent work, we examined a particular aspect of the appreciation of artwork using present-day functional magnetic resonance imaging (fMRI. Our results emphasised the continuity between viewing artwork and other human cognitive activities. We also showed that appreciation of a particular aspect of artwork, namely authenticity, depends upon the co-ordinated activity between the brain regions involved in multiple decision making and those responsible for processing visual information. The findings about brain function probably have no specific consequences for understanding how people respond to the art of Rembrandt in comparison with their response to other artworks. However, the use of images of Rembrandt’s portraits, his most intimate and personal works, clearly had a significant impact upon our viewers, even though they have been spatially confined to the interior of an MRI scanner at the time of viewing. Neuroscientific studies of humans viewing artwork have the capacity to reveal the diversity of human cognitive responses that may be induced by external advice or context as people view artwork in a variety of frameworks and settings.

  15. Models of bounded rationality under certainty

    NARCIS (Netherlands)

    Rasouli, S.; Timmermans, H.J.P.; Rasouli, S.; Timmermans, H.J.P.

    2015-01-01

    Purpose This chapter reviews models of decision-making and choice under conditions of certainty. It allows readers to position the contribution of the other chapters in this book in the historical development of the topic area. Theory Bounded rationality is defined in terms of a strategy to simplify

  16. Sobolev spaces on bounded symmetric domains

    Czech Academy of Sciences Publication Activity Database

    Engliš, Miroslav

    Roč. 60, č. 12 ( 2015 ), s. 1712-1726 ISSN 1747-6933 Institutional support: RVO:67985840 Keywords : bounded symmetric domain * Sobolev space * Bergman space Subject RIV: BA - General Mathematics Impact factor: 0.466, year: 2015 http://www.tandfonline.com/doi/abs/10.1080/17476933. 2015 .1043910

  17. Properties of Excitons Bound to Ionized Donors

    DEFF Research Database (Denmark)

    Skettrup, Torben; Suffczynski, M.; Gorzkowski, W.

    1971-01-01

    Binding energies, interparticle distances, oscillator strengths, and exchange corrections are calculated for the three-particle complex corresponding to an exciton bound to an ionized donor. The results are given as functions of the mass ratio of the electron and hole. Binding of the complex is o...

  18. Bogomol'nyi bounds for cosmic strings

    International Nuclear Information System (INIS)

    Comtet, A.; Gibbons, G.W.; Cambridge Univ.

    1987-09-01

    We establish Bogomol'nyi inequalities for the deficit angle of some cylindrically symmetric asymptotically local flat (CALF) spacetimes containing cosmic strings. These results prove the stability against arbitrary cylindrical deformations of those configurations which saturate the bound. Such configurations satisfy first order equations which can, in some cases, be solved exactly

  19. Bounding the bias of contrastive divergence learning

    DEFF Research Database (Denmark)

    Fischer, Anja; Igel, Christian

    2011-01-01

    Optimization based on k-step contrastive divergence (CD) has become a common way to train restricted Boltzmann machines (RBMs). The k-step CD is a biased estimator of the log-likelihood gradient relying on Gibbs sampling. We derive a new upper bound for this bias. Its magnitude depends on k...

  20. Bound States in the Mirror TBA

    NARCIS (Netherlands)

    Arutyunov, G.E.; Frolov, S.; van Tongeren, S.J.

    2012-01-01

    The spectrum of the light-cone AdS_5 \\times S^5 superstring contains states composed of particles with complex momenta including in particular those which turn into bound states in the decompactification limit. We propose the mirror TBA description for these states. We focus on a three-particle

  1. Harmonic maps of the bounded symmetric domains

    International Nuclear Information System (INIS)

    Xin, Y.L.

    1994-06-01

    A shrinking property of harmonic maps into R IV (2) is proved which is used to classify complete spacelike surfaces of the parallel mean curvature in R 4 2 with a reasonable condition on the Gauss image. Liouville-type theorems of harmonic maps from the higher dimensional bounded symmetric domains are also established. (author). 25 refs

  2. Scattering theory methods for bound state problems

    International Nuclear Information System (INIS)

    Raphael, R.B.; Tobocman, W.

    1978-01-01

    For the analysis of the properties of a bound state system one may use in place of the Schroedinger equation the Lippmann-Schwinger (LS) equation for the wave function or the LS equation for the reactance operator. Use of the LS equation for the reactance operator constrains the solution to have correct asymptotic behaviour, so this approach would appear to be desirable when the bound state wave function is to be used to calculate particle transfer form factors. The Schroedinger equation based N-level analysis of the s-wave bound states of a square well is compared to the ones based on the LS equation. It is found that the LS equation methods work better than the Schroedinger equation method. The method that uses the LS equation for the wave function gives the best results for the wave functions while the method that uses the LS equation for the reactance operator gives the best results for the binding energies. The accuracy of the reactance operator based method is remarkably insensitive to changes in the oscillator constant used for the harmonic oscillator function basis set. It is also remarkably insensitive to the number of nodes in the bound state wave function. (Auth.)

  3. Lower bounds on scintillation detector timing performance

    International Nuclear Information System (INIS)

    Clinthorne, N.H.; Rogers, W.L.; Hero, A.O. III.; Petrick, N.A.

    1990-01-01

    Fundamental method-independent limits on the timing performance of scintillation detectors are useful for identifying regimes in which either present timing methods are nearly optimal or where a considerable performance gain might be realized using better pulse processing techniques. Several types of lower bounds on mean-squared timing error (MSE) performance have been developed and applied to scintillation detectors. The simple Cramer-Rao (CR) bound can be useful in determining the limiting MSE for scintillators having a relatively high rate of photon problction such as BaF 2 and NaI(Tl); however, it tends to overestimate the achievalbe performance for scintillators with lower rates such as BGO. For this reason, alternative bounds have been developed using rate-distortion theory or by assuming that the conversion of energy to scintillation light must pass through excited states which have exponential lifetime densities. The bounds are functions of the mean scintillation pulse shape, the scintillation intensity, and photodetector characteristics; they are simple to evaluate and can be used to conveniently assess the limiting timing performance of scintillation detectors. (orig.)

  4. Efficiency gains, bounds, and risk in finance

    NARCIS (Netherlands)

    Sarisoy, Cisil

    2015-01-01

    This thesis consists of three chapters. The first chapter analyzes efficiency gains in the estimation of expected returns based on asset pricing models and examines the economic implications of such gains in portfolio allocation exercises. The second chapter provides nonparametric efficiency bounds

  5. Book Selection, Collection Development, and Bounded Rationality.

    Science.gov (United States)

    Schwartz, Charles A.

    1989-01-01

    Reviews previously proposed schemes of classical rationality in book selection, describes new approaches to rational choice behavior, and presents a model of book selection based on bounded rationality in a garbage can decision process. The role of tacit knowledge and symbolic content in the selection process are also discussed. (102 references)…

  6. Monotonicity and bounds on Bessel functions

    Directory of Open Access Journals (Sweden)

    Larry Landau

    2000-07-01

    Full Text Available survey my recent results on monotonicity with respect to order of general Bessel functions, which follow from a new identity and lead to best possible uniform bounds. Application may be made to the "spreading of the wave packet" for a free quantum particle on a lattice and to estimates for perturbative expansions.

  7. Collisional properties of weakly bound heteronuclear dimers

    NARCIS (Netherlands)

    Marcelis, B.; Kokkelmans, S.J.J.M.F.; Shlyapnikov, G.V.; Petrov, D.S.

    2008-01-01

    We consider collisional properties of weakly bound heteronuclear molecules (dimers) formed in a two-species mixture of atoms with a large mass difference. We focus on dimers containing light fermionic atoms as they manifest collisional stability due to an effective dimer-dimer repulsion originating

  8. Bounded Rationality of Generalized Abstract Fuzzy Economies

    Directory of Open Access Journals (Sweden)

    Lei Wang

    2014-01-01

    Full Text Available By using a nonlinear scalarization technique, the bounded rationality model M for generalized abstract fuzzy economies in finite continuous spaces is established. Furthermore, by using the model M, some new theorems for structural stability and robustness to (λ,ϵ-equilibria of generalized abstract fuzzy economies are proved.

  9. Bounded Rationality in Individual Decision Making

    OpenAIRE

    Camerer, Colin F.

    1998-01-01

    The main objectives of this paper are: (i) To give a pithy, opinionated summary of what has been learned about bounded rationality in individual decision making from experiments in economics and psychology (drawing on my 1995 Handbook of Experimental Economics chapter); and (ii) mention some promising new directions for research which would be included if that chapter were written today.

  10. Sharp Bounds for Symmetric and Asymmetric Diophantine Approximation

    Institute of Scientific and Technical Information of China (English)

    Cornelis KRAAIKAMP; Ionica SMEETS

    2011-01-01

    In 2004,Tong found bounds for the approximation quality of a regular continued fraction convergent to a rational number,expressed in bounds for both the previous and next approximation.The authors sharpen his results with a geometric method and give both sharp upper and lower bounds.The asymptotic frequencies that these bounds occur are also calculated.

  11. Bounds on fluid permeability for viscous flow through porous media

    International Nuclear Information System (INIS)

    Berryman, J.G.

    1985-01-01

    General properties of variational bounds on Darcy's constant for slow viscous flow through porous media are studied. The bounds are also evaluated numerically for the penetrable sphere model. The bound of Doi depending on two-point correlations and the analytical bound of Weissberg and Prager give comparable results in the low density limit but the analytical bound is superior for higher densities. Prager's bound depending on three-point correlation functions is worse than the analytical bound at low densities but better (although comparable to it) at high densities. A procedure for methodically improving Prager's three point bound is presented. By introducing a Gaussian trial function, the three-point bound is improved by an order of magnitude for moderate values of porosity. The new bounds are comparable in magnitude to the Kozeny--Carman empirical relation for porous materials

  12. Surface functionalization of PLGA nanoparticles by non-covalent insertion of a homo-bifunctional spacer for active targeting in cancer therapy

    Science.gov (United States)

    Thamake, S. I.; Raut, S. L.; Ranjan, A. P.; Gryczynski, Z.; Vishwanatha, J. K.

    2011-01-01

    This work reports the surface functionalization of polymeric PLGA nanoparticles by non-covalent insertion of a homo-bifunctional chemical crosslinker, bis(sulfosuccinimidyl) suberate (BS3) for targeted cancer therapy. We dissolved BS3 in aqueous solution of PVA during formulation of nanoparticles by a modified solid/oil/water emulsion solvent evaporation method. The non-covalent insertion of BS3 was confirmed by Fourier transform infrared (FTIR) spectroscopy. Curcumin and annexin A2 were used as a model drug and a cell specific target, respectively. Nanoparticles were characterized for particle size, zeta potential and surface morphology. The qualitative assessment of antibody attachment was performed by transmission electron microscopy (TEM) as well as confocal microscopy. The optimized formulation showed antibody attachment of 86%. However, antibody attachment was abolished upon blocking the functional groups of BS3. The availability of functional antibodies was evaluated by the presence of a light chain fraction after gel electrophoresis. We further evaluated the in vitro release kinetics of curcumin from antibody coated and uncoated nanoparticles. The release of curcumin is enhanced upon antibody attachment and followed an anomalous release pattern. We also observed that the cellular uptake of nanoparticles was significantly higher in annexin A2 positive cells than in negative cells. Therefore, these results demonstrate the potential use of this method for functionalization as well as to deliver chemotherapeutic agents for treating cancer.

  13. Non-covalent conjugation of cutinase from Fusarium sp. ICT SAC1 with pectin for enhanced stability: Process minutiae, kinetics, thermodynamics and structural study.

    Science.gov (United States)

    Muley, Abhijeet B; Chaudhari, Sandeep A; Singhal, Rekha S

    2017-09-01

    Cutinase, a member of α/β-fold hydrolase family possess potentially diverse applications in several industrial processes and products. The present work aims towards thermo-stabilization of cutinase from novel source Fusarium sp. ICT SAC1 via non-covalent interaction with polysaccharides. Although all six polysaccharides chosen for study enhanced the thermal stability, pectin was found to be most promising. The interaction protocol for cutinase with pectin was optimized sequentially with respect to the ratio of enzyme to pectin, solution pH, and buffer strength. Cutinase-pectin conjugate under optimized conditions (1:12, pH-6.5, 50mM) showed enhanced thermal stability as evident from lower inactivation rate constant, higher half-life and D-value within the 40-55°C. A slender rise in K m and V max values and enhanced thermodynamic parameters of cutinase-pectin conjugate were observed after non-covalent interaction. Entropy values were 1.5-fold higher for cutinase-pectin conjugate at each temperature suggesting an upsurge in number of protein molecules in a transition activated state. Positive values of entropy for both forms of cutinase suggested a rise in disordered conformation. Noticeable conformational changes in cutinase after conjugation with pectin were confirmed by FTIR as well as fluorescence emission spectra. An increment in helix to turn conversion was observed in complexed cutinase vis-à-vis free cutinase. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Surface functionalization of PLGA nanoparticles by non-covalent insertion of a homo-bifunctional spacer for active targeting in cancer therapy

    Energy Technology Data Exchange (ETDEWEB)

    Thamake, S I; Raut, S L [Department of Biomedical Sciences, University of North Texas Health Science Center at Fort Worth, Fort Worth, TX 76107 (United States); Ranjan, A P; Vishwanatha, J K [Department of Molecular Biology and Immunology, University of North Texas Health Science Center, Fort Worth, TX 76107 (United States); Gryczynski, Z, E-mail: jamboor.vishwanatha@unthsc.edu [Center for Commercialization of Fluorescence Technology, University of North Texas Health Science Center, Fort Worth, TX 76107 (United States)

    2011-01-21

    This work reports the surface functionalization of polymeric PLGA nanoparticles by non-covalent insertion of a homo-bifunctional chemical crosslinker, bis(sulfosuccinimidyl) suberate (BS3) for targeted cancer therapy. We dissolved BS3 in aqueous solution of PVA during formulation of nanoparticles by a modified solid/oil/water emulsion solvent evaporation method. The non-covalent insertion of BS3 was confirmed by Fourier transform infrared (FTIR) spectroscopy. Curcumin and annexin A2 were used as a model drug and a cell specific target, respectively. Nanoparticles were characterized for particle size, zeta potential and surface morphology. The qualitative assessment of antibody attachment was performed by transmission electron microscopy (TEM) as well as confocal microscopy. The optimized formulation showed antibody attachment of 86%. However, antibody attachment was abolished upon blocking the functional groups of BS3. The availability of functional antibodies was evaluated by the presence of a light chain fraction after gel electrophoresis. We further evaluated the in vitro release kinetics of curcumin from antibody coated and uncoated nanoparticles. The release of curcumin is enhanced upon antibody attachment and followed an anomalous release pattern. We also observed that the cellular uptake of nanoparticles was significantly higher in annexin A2 positive cells than in negative cells. Therefore, these results demonstrate the potential use of this method for functionalization as well as to deliver chemotherapeutic agents for treating cancer.

  15. Preparation of non-aggregated fluorescent nanodiamonds (FNDs) by non-covalent coating with a block copolymer and proteins for enhancement of intracellular uptake.

    Science.gov (United States)

    Lee, Jong Woo; Lee, Seonju; Jang, Sangmok; Han, Kyu Young; Kim, Younggyu; Hyun, Jaekyung; Kim, Seong Keun; Lee, Yan

    2013-05-01

    Fluorescent nanodiamonds (FNDs) are very promising fluorophores for use in biosystems due to their high biocompatibility and photostability. To overcome their tendency to aggregate in physiological solutions, which severely limits the biological applications of FNDs, we developed a new non-covalent coating method using a block copolymer, PEG-b-P(DMAEMA-co-BMA), or proteins such as BSA and HSA. By simple mixing of the block copolymer with FNDs, the cationic DMAEMA and hydrophobic BMA moieties can strongly interact with the anionic and hydrophobic moieties on the FND surface, while the PEG block can form a shell to prevent the direct contact between FNDs. The polymer-coated FNDs, along with BSA- and HSA-coated FNDs, showed non-aggregation characteristics and maintained their size at the physiological salt concentration. The well-dispersed, polymer- or protein-coated FNDs in physiological solutions showed enhanced intracellular uptake, which was confirmed by CLSM. In addition, the biocompatibility of the coated FNDs was expressly supported by a cytotoxicity assay. Our simple non-covalent coating with the block copolymer, which can be easily modified by various chemical methods, projects a very promising outlook for future biomedical applications, especially in comparison with covalent coating or protein-based coating.

  16. Determination of Noncovalent Binding Using a Continuous Stirred Tank Reactor as a Flow Injection Device Coupled to Electrospray Ionization Mass Spectrometry

    Science.gov (United States)

    Santos, Inês C.; Waybright, Veronica B.; Fan, Hui; Ramirez, Sabra; Mesquita, Raquel B. R.; Rangel, António O. S. S.; Fryčák, Petr; Schug, Kevin A.

    2015-07-01

    Described is a new method based on the concept of controlled band dispersion, achieved by hyphenating flow injection analysis with ESI-MS for noncovalent binding determinations. A continuous stirred tank reactor (CSTR) was used as a FIA device for exponential dilution of an equimolar host-guest solution over time. The data obtained was treated for the noncovalent binding determination using an equimolar binding model. Dissociation constants between vancomycin and Ac-Lys(Ac)-Ala-Ala-OH peptide stereoisomers were determined using both the positive and negative ionization modes. The results obtained for Ac- L-Lys(Ac)- D-Ala- D-Ala (a model for a Gram-positive bacterial cell wall) binding were in reasonable agreement with literature values made by other mass spectrometry binding determination techniques. Also, the developed method allowed the determination of dissociation constants for vancomycin with Ac- L-Lys(Ac)- D-Ala- L-Ala, Ac- L-Lys(Ac)- L-Ala- D-Ala, and Ac- L-Lys(Ac)- L-Ala- L-Ala. Although some differences in measured binding affinities were noted using different ionization modes, the results of each determination were generally consistent. Differences are likely attributable to the influence of a pseudo-physiological ammonium acetate buffer solution on the formation of positively- and negatively-charged ionic complexes.

  17. Upper bounds for reversible circuits based on Young subgroups

    DEFF Research Database (Denmark)

    Abdessaied, Nabila; Soeken, Mathias; Thomsen, Michael Kirkedal

    2014-01-01

    We present tighter upper bounds on the number of Toffoli gates needed in reversible circuits. Both multiple controlled Toffoli gates and mixed polarity Toffoli gates have been considered for this purpose. The calculation of the bounds is based on a synthesis approach based on Young subgroups...... that results in circuits using a more generalized gate library. Starting from an upper bound for this library we derive new bounds which improve the existing bound by around 77%....

  18. Chirality of weakly bound complexes: The potential energy surfaces for the hydrogen-peroxide−noble-gas interactions

    Energy Technology Data Exchange (ETDEWEB)

    Roncaratti, L. F., E-mail: lz@fis.unb.br; Leal, L. A.; Silva, G. M. de [Instituto de Física, Universidade de Brasília, 70910 Brasília (Brazil); Pirani, F. [Dipartimento di Chimica, Biologia e Biotecnologie, Università di Perugia, 06123 Perugia (Italy); Aquilanti, V. [Dipartimento di Chimica, Biologia e Biotecnologie, Università di Perugia, 06123 Perugia (Italy); Instituto de Física, Universidade Federal da Bahia, 40210 Salvador (Brazil); Gargano, R. [Instituto de Física, Universidade de Brasília, 70910 Brasília (Brazil); Departments of Chemistry and Physics, University of Florida, Quantum Theory Project, Gainesville, Florida 32611 (United States)

    2014-10-07

    We consider the analytical representation of the potential energy surfaces of relevance for the intermolecular dynamics of weakly bound complexes of chiral molecules. In this paper we study the H{sub 2}O{sub 2}−Ng (Ng=He, Ne, Ar, Kr, and Xe) systems providing the radial and the angular dependence of the potential energy surface on the relative position of the Ng atom. We accomplish this by introducing an analytical representation which is able to fit the ab initio energies of these complexes in a wide range of geometries. Our analysis sheds light on the role that the enantiomeric forms and the symmetry of the H{sub 2}O{sub 2} molecule play on the resulting barriers and equilibrium geometries. The proposed theoretical framework is useful to study the dynamics of the H{sub 2}O{sub 2} molecule, or other systems involving O–O and S–S bonds, interacting by non-covalent forces with atoms or molecules and to understand how the relative orientation of the O–H bonds changes along collisional events that may lead to a hydrogen bond formation or even to selectivity in chemical reactions.

  19. Optima and bounds for irreversible thermodynamic processes

    International Nuclear Information System (INIS)

    Hoffmann, K.H.

    1990-01-01

    In this paper bounds and optima for irreversible thermodynamic processes and their application in different fields are discussed. The tools of finite time thermodynamics are presented and especially optimal control theory is introduced. These methods are applied to heat engines, including models of the Diesel engine and a light-driven engine. Further bounds for irreversible processes are introduced, discussing work deficiency and its relation to thermodynamic length. Moreover the problem of dissipation in systems composed of several subsystems is studied. Finally, the methods of finite time thermodynamics are applied to thermodynamic processes described on a more microscopic level. The process used as an example is simulated annealing. It is shown how optimal control theory is applied to find the optimal cooling schedule for this important stochastic optimization method

  20. Bounded excursion stable gravastars and black holes

    Energy Technology Data Exchange (ETDEWEB)

    Rocha, P [Instituto de Fisica, Universidade Federal Fluminense, Avenida Litoranea, s/n, Boa Viagem 24210-340, Niteroi, RJ (Brazil); Miguelote, A Y; Chan, R [Coordenacao de Astronomia e Astrofisica, Observatorio Nacional, Rua General Jose Cristino, 77, Sao Cristovao 20921-400, Rio de Janeiro, RJ (Brazil); Da Silva, M F; Wang, Anzhong [Departamento de Fisica Teorica, Instituto de Fisica, Universidade do Estado do Rio de Janeiro, Rua Sao Francisco Xavier 524, Maracana 20550-900, Rio de Janeiro-RJ (Brazil); Santos, N O, E-mail: pedrosennarocha@gmail.com, E-mail: yasuda@on.br, E-mail: chan@on.br, E-mail: mfasnic@gmail.com, E-mail: N.O.Santos@qmul.ac.uk, E-mail: anzhong_wang@baylor.edu [LERMA/CNRS-FRE 2460, Universite Pierre et Marie Curie, ERGA, Boite 142, 4 Place Jussieu, 75005 Paris Cedex 05 (France)

    2008-06-15

    Dynamical models of prototype gravastars were constructed in order to study their stability. The models are the Visser-Wiltshire three-layer gravastars, in which an infinitely thin spherical shell of stiff fluid divides the whole spacetime into two regions, where the internal region is de Sitter, and the external one is Schwarzschild. It is found that in some cases the models represent the 'bounded excursion' stable gravastars, where the thin shell is oscillating between two finite radii, while in other cases they collapse until the formation of black holes occurs. In the phase space, the region for the 'bounded excursion' gravastars is very small in comparison to that of black holes, but not empty. Therefore, although the possibility of the existence of gravastars cannot be excluded from such dynamical models, our results indicate that, even if gravastars do indeed exist, that does not exclude the possibility of the existence of black holes.

  1. Optimal Bounds in Parametric LTL Games

    Directory of Open Access Journals (Sweden)

    Martin Zimmermann

    2011-06-01

    Full Text Available We consider graph games of infinite duration with winning conditions in parameterized linear temporal logic, where the temporal operators are equipped with variables for time bounds. In model checking such specifications were introduced as "PLTL" by Alur et al. and (in a different version called "PROMPT-LTL" by Kupferman et al.. We present an algorithm to determine optimal variable valuations that allow a player to win a game. Furthermore, we show how to determine whether a player wins a game with respect to some, infinitely many, or all valuations. All our algorithms run in doubly-exponential time; so, adding bounded temporal operators does not increase the complexity compared to solving plain LTL games.

  2. Asymptotic Sharpness of Bounds on Hypertrees

    Directory of Open Access Journals (Sweden)

    Lin Yi

    2017-08-01

    Full Text Available The hypertree can be defined in many different ways. Katona and Szabó introduced a new, natural definition of hypertrees in uniform hypergraphs and investigated bounds on the number of edges of the hypertrees. They showed that a k-uniform hypertree on n vertices has at most (nk−1$\\left( {\\matrix{n \\cr {k - 1} } } \\right$ edges and they conjectured that the upper bound is asymptotically sharp. Recently, Szabó verified that the conjecture holds by recursively constructing an infinite sequence of k-uniform hypertrees and making complicated analyses for it. In this note we give a short proof of the conjecture by directly constructing a sequence of k-uniform k-hypertrees.

  3. A holographic bound for D3-brane

    Energy Technology Data Exchange (ETDEWEB)

    Momeni, Davood; Myrzakul, Aizhan; Myrzakulov, Ratbay [Eurasian National University, Eurasian International Center for Theoretical Physics, Astana (Kazakhstan); Eurasian National University, Department of General Theoretical Physics, Astana (Kazakhstan); Faizal, Mir [University of British Columbia-Okanagan, Irving K. Barber School of Arts and Sciences, Kelowna, BC (Canada); University of Lethbridge, Department of Physics and Astronomy, Lethbridge, AB (Canada); Bahamonde, Sebastian [University College London, Department of Mathematics, London (United Kingdom)

    2017-06-15

    In this paper, we will regularize the holographic entanglement entropy, holographic complexity and fidelity susceptibility for a configuration of D3-branes. We will also study the regularization of the holographic complexity from the action for a configuration of D3-branes. It will be demonstrated that for a spherical shell of D3-branes the regularized holographic complexity is always greater than or equal to the regularized fidelity susceptibility. Furthermore, we will also demonstrate that the regularized holographic complexity is related to the regularized holographic entanglement entropy for this system. Thus, we will obtain a holographic bound involving regularized holographic complexity, regularized holographic entanglement entropy and regularized fidelity susceptibility of a configuration of D3-brane. We will also discuss a bound for regularized holographic complexity from action, for a D3-brane configuration. (orig.)

  4. Bound states in weakly disordered spin ladders

    Energy Technology Data Exchange (ETDEWEB)

    Arlego, M. [Departamento de Fisica, Universidad Nacional de La Plata, CC 67 (1900) La Plata (Argentina)]. E-mail: arlego@venus.fisica.unlp.edu.ar; Brenig, W. [Institut fuer Theoretische Physik, Technische Universitaet Braunschweig (Germany); Cabra, D.C. [Laboratoire de Physique Theorique, Universite Louis Pasteur Strasbourg (France); Heidrich-Meisner, F. [Institut fuer Theoretische Physik, Technische Universitaet Braunschweig (Germany); Honecker, A. [Institut fuer Theoretische Physik, Technische Universitaet Braunschweig (Germany); Rossini, G. [Departamento de Fisica, Universidad Nacional de La Plata, CC 67 (1900) La Plata (Argentina)

    2005-04-30

    We study the appearance of bound states in the spin gap of spin-12 ladders induced by weak bond disorder. Starting from the strong-coupling limit, i.e., the limit of weakly coupled dimers, we perform a projection on the single-triplet subspace and derive the position of bound states for the single impurity problem of one modified coupling as well as for small impurity clusters. The case of a finite concentration of impurities is treated with the coherent-potential approximation (CPA) in the strong-coupling limit and compared with numerical results. Further, we analyze the details in the structure of the density of states and relate their origin to the influence of impurity clusters.

  5. Entanglement detection with bounded reference frames

    International Nuclear Information System (INIS)

    Costa, Fabio; Brukner, Caslav; Harrigan, Nicholas; Rudolph, Terry

    2009-01-01

    Quantum experiments usually assume the existence of perfect, classical reference frames (RFs), which allow for the specification of measurement settings (e.g. orientation of the Stern-Gerlach magnet in spin measurements) with arbitrary precision. If the RFs are 'bounded' (i.e. quantum systems themselves, having a finite number of degrees of freedom), only limited precision can be attained. Using spin coherent states as bounded RFs, we have found the minimum size needed for them to violate local realism for entangled spin systems. For composite systems of spin 1/2 particles, RFs of very small size are sufficient for the violation; however, to see this violation for macroscopic entangled spins, the size of the RF must be at least quadratically larger than that of the spins. The unavailability of such RFs gives a possible explanation for the non-observance of violation of local realism in everyday experience.

  6. A proof of the conformal collider bounds

    Energy Technology Data Exchange (ETDEWEB)

    Hofman, Diego M. [Institute for Theoretical Physics, University of Amsterdam, Science Park 904, Postbus 94485, 1090 GL, Amsterdam (Netherlands); Li, Daliang [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States); Meltzer, David [Department of Physics, Yale University, New Haven, CT 06511 (United States); Poland, David [Department of Physics, Yale University, New Haven, CT 06511 (United States); School of Natural Sciences, Institute for Advanced Study, Princeton, NJ 08540 (United States); Rejon-Barrera, Fernando [Institute for Theoretical Physics, University of Amsterdam, Science Park 904, Postbus 94485, 1090 GL, Amsterdam (Netherlands)

    2016-06-20

    In this paper, we prove that the “conformal collider bounds” originally proposed in http://dx.doi.org/10.1088/1126-6708/2008/05/012 hold for any unitary parity-preserving conformal field theory (CFT) with a unique stress tensor in dimensions d≥3. In particular this implies that the ratio of central charges for a unitary 4d CFT lies in the interval (31/18)≥(a/c)≥(1/3). For superconformal theories this is further reduced to (3/2)≥(a/c)≥(1/2). The proof relies only on CFT first principles — in particular, bootstrap methods — and thus constitutes the first complete field theory proof of these bounds. We further elaborate on similar bounds for non-conserved currents and relate them to results obtained recently from deep inelastic scattering.

  7. Efficiency bounds for nonequilibrium heat engines

    International Nuclear Information System (INIS)

    Mehta, Pankaj; Polkovnikov, Anatoli

    2013-01-01

    We analyze the efficiency of thermal engines (either quantum or classical) working with a single heat reservoir like an atmosphere. The engine first gets an energy intake, which can be done in an arbitrary nonequilibrium way e.g. combustion of fuel. Then the engine performs the work and returns to the initial state. We distinguish two general classes of engines where the working body first equilibrates within itself and then performs the work (ergodic engine) or when it performs the work before equilibrating (non-ergodic engine). We show that in both cases the second law of thermodynamics limits their efficiency. For ergodic engines we find a rigorous upper bound for the efficiency, which is strictly smaller than the equivalent Carnot efficiency. I.e. the Carnot efficiency can be never achieved in single reservoir heat engines. For non-ergodic engines the efficiency can be higher and can exceed the equilibrium Carnot bound. By extending the fundamental thermodynamic relation to nonequilibrium processes, we find a rigorous thermodynamic bound for the efficiency of both ergodic and non-ergodic engines and show that it is given by the relative entropy of the nonequilibrium and initial equilibrium distributions. These results suggest a new general strategy for designing more efficient engines. We illustrate our ideas by using simple examples. -- Highlights: ► Derived efficiency bounds for heat engines working with a single reservoir. ► Analyzed both ergodic and non-ergodic engines. ► Showed that non-ergodic engines can be more efficient. ► Extended fundamental thermodynamic relation to arbitrary nonequilibrium processes

  8. Recent advances in bound state quantum electrodynamics

    International Nuclear Information System (INIS)

    Brodsky, S.J.; Lepage, G.P.

    1977-06-01

    Recent developments are reviewed in four areas of computational quantum electrodynamics: a new relativistic two-body formalism equal in rigor to the Bethe-Salpeter formalism but with strong calculational advantages is discussed; recent work on the computation of the decay rate of bound systems (positronium in particular) is presented; limits on possible composite structure of leptons are discussed; a new multidimensional integration program ('VEGAS') suitable for higher order calculations is presented

  9. Bounding probabilistic safety assessment probabilities by reality

    International Nuclear Information System (INIS)

    Fragola, J.R.; Shooman, M.L.

    1991-01-01

    The investigation of the failure in systems where failure is a rare event makes the continual comparisons between the developed probabilities and empirical evidence difficult. The comparison of the predictions of rare event risk assessments with historical reality is essential to prevent probabilistic safety assessment (PSA) predictions from drifting into fantasy. One approach to performing such comparisons is to search out and assign probabilities to natural events which, while extremely rare, have a basis in the history of natural phenomena or human activities. For example the Segovian aqueduct and some of the Roman fortresses in Spain have existed for several millennia and in many cases show no physical signs of earthquake damage. This evidence could be used to bound the probability of earthquakes above a certain magnitude to less than 10 -3 per year. On the other hand, there is evidence that some repetitive actions can be performed with extremely low historical probabilities when operators are properly trained and motivated, and sufficient warning indicators are provided. The point is not that low probability estimates are impossible, but continual reassessment of the analysis assumptions, and a bounding of the analysis predictions by historical reality. This paper reviews the probabilistic predictions of PSA in this light, attempts to develop, in a general way, the limits which can be historically established and the consequent bounds that these limits place upon the predictions, and illustrates the methodology used in computing such limits. Further, the paper discusses the use of empirical evidence and the requirement for disciplined systematic approaches within the bounds of reality and the associated impact on PSA probabilistic estimates

  10. Multipartite secret key distillation and bound entanglement

    International Nuclear Information System (INIS)

    Augusiak, Remigiusz; Horodecki, Pawel

    2009-01-01

    Recently it has been shown that quantum cryptography beyond pure entanglement distillation is possible and a paradigm for the associated protocols has been established. Here we systematically generalize the whole paradigm to the multipartite scenario. We provide constructions of new classes of multipartite bound entangled states, i.e., those with underlying twisted Greenberger-Horne-Zeilinger (GHZ) structure and nonzero distillable cryptographic key. We quantitatively estimate the key from below with the help of the privacy squeezing technique.

  11. Closed form bound-state perturbation theory

    Directory of Open Access Journals (Sweden)

    Ollie J. Rose

    1980-01-01

    Full Text Available The perturbed Schrödinger eigenvalue problem for bound states is cast into integral form using Green's Functions. A systematic algorithm is developed and applied to the resulting equation giving rise to approximate solutions expressed as functions of the given perturbation parameter. As a by-product, convergence radii for the traditional Rayleigh-Schrödinger and Brillouin-Wigner perturbation theories emerge in a natural way.

  12. Exact BPS bound for noncommutative baby Skyrmions

    International Nuclear Information System (INIS)

    Domrin, Andrei; Lechtenfeld, Olaf; Linares, Román; Maceda, Marco

    2013-01-01

    The noncommutative baby Skyrme model is a Moyal deformation of the two-dimensional sigma model plus a Skyrme term, with a group-valued or Grassmannian target. Exact abelian solitonic solutions have been identified analytically in this model, with a singular commutative limit. Inside any given Grassmannian, we establish a BPS bound for the energy functional, which is saturated by these baby Skyrmions. This asserts their stability for unit charge, as we also test in second-order perturbation theory

  13. The organically bound tritium: an analyst vision

    International Nuclear Information System (INIS)

    Ansoborlo, E.; Baglan, N.

    2009-01-01

    The authors report the work of a work group on tritium analysis. They recall the different physical forms of tritium: gas (HT, hydrogen-tritium), water vapour (HTO or tritiated water) or methane (CH3T), but also in organic compounds (OBT, organically bound tritium) which are either exchangeable or non-exchangeable. They evoke measurement techniques and methods, notably to determine the tritium volume activity. They discuss the possibilities to analyse and distinguish exchangeable and non-exchangeable OBTs

  14. New approach to calculate bound state eigenvalues

    International Nuclear Information System (INIS)

    Gerck, E.; Gallas, J.A.C.

    1983-01-01

    A method of solving the radial Schrodinger equation for bound states is discussed. The method is based on a new piecewise representation of the second derivative operator on a set of functions that obey the boundary conditions. This representation is trivially diagonalised and leads to closed form expressions of the type E sub(n)=E(ab+b+c/n+...) for the eigenvalues. Examples are given for the power-law and logarithmic potentials. (Author) [pt

  15. A sorting network in bounded arithmetic

    Czech Academy of Sciences Publication Activity Database

    Jeřábek, Emil

    2011-01-01

    Roč. 162, č. 4 (2011), s. 341-355 ISSN 0168-0072 R&D Projects: GA AV ČR IAA1019401; GA MŠk(CZ) 1M0545 Institutional research plan: CEZ:AV0Z10190503 Keywords : bounded arithmetic * sorting network * proof complexity * monotone sequent calculus Subject RIV: BA - General Mathematics Impact factor: 0.450, year: 2011 http://www.sciencedirect.com/science/article/pii/S0168007210001272

  16. Heterogeneity, Bounded Rationality and Market Dysfunctionality

    OpenAIRE

    Xue-Zhong He; Lei Shi

    2008-01-01

    As the main building blocks of the modern finance theory, homogeneity and rational expectation have faced difficulty in explaining many market anomalies, stylized factors, and market inefficiency in empirical studies. As a result, heterogeneity and bounded rationality have been used as an alterative paradigm of asset price dynamics and this paradigm has been widely recognized recently in both academic and financial market practitioners. Within the framework of Chiarella, Dieci and He (2006a, ...

  17. Kinetic simulation on collisional bounded plasma

    International Nuclear Information System (INIS)

    Zhu, S.P.; Sato, Tetsuya; Tomita, Yukihiro; Hatori, Tadatsugu

    1998-01-01

    A self-consistent kinetic simulation model on collisional bounded plasma is presented. The electric field is given by solving Poisson equation and collisions among particles (including charged particles and neutral particles) are included. The excitation and ionization of neutral particle, and recombination are also contained in the present model. The formation of potential structure near a boundary for a discharge system was used as an application of this model. (author)

  18. Analysis of the organically bound tritium

    International Nuclear Information System (INIS)

    Baglan, N.; Alanic, G.

    2011-01-01

    In environmental samples, tritium is very often combined with the fraction of bulk water accumulated in the sample but also in the form of organically bound tritium. When the tritium is organically bound, 2 forms can coexist: the exchangeable fraction and the non-exchangeable fraction. The analysis of the different forms of tritium present in the sample is necessary to assess the sanitary hazards due to tritium. The total tritium is obtained from the analysis of the water released when the fresh sample is burnt while the organically bound tritium is obtained from the analysis of the water released when the dry extract of the sample is burnt. The measurement of the exchangeable fraction and the non-exchangeable fraction requires an additional stage of labile exchange. The exchangeable fraction is determined from the analysis of the water released during the labile exchange and the non-exchangeable fraction is determined from the water released during the combustion of the dry extract of the labile exchange

  19. Search for quasi bound η mesons

    International Nuclear Information System (INIS)

    Machner, H

    2015-01-01

    The search for a quasi bound η meson in atomic nuclei is reviewed. This tentative state is studied theoretically as well as experimentally. The theory starts from elastic η nucleon scattering which is derived from production data within some models. From this interaction the η nucleus interaction is derived. Model calculations predict binding energies and widths of the quasi bound state. Another method is to derive the η nucleus interaction from excitation functions of η production experiments. The s wave interaction is extracted from such data via final state interaction (FSI) theorem. We give the derivation of s wave amplitudes in partial wave expansion and in helicity amplitudes and their relation to observables. Different experiments extracting the FSI are discussed as are production experiments. So far only three experiments give evidence for the existence of the quasi bound state: a pion double charge exchange experiment, an effective mass measurement, and a transfer reaction at recoil free kinematics with observation of the decay of the state. (topical review)

  20. Lower bounds for the minimum distance of algebraic geometry codes

    DEFF Research Database (Denmark)

    Beelen, Peter

    , such as the Goppa bound, the Feng-Rao bound and the Kirfel-Pellikaan bound. I will finish my talk by giving several examples. Especially for two-point codes, the generalized order bound is fairly easy to compute. As an illustration, I will indicate how a lower bound can be obtained for the minimum distance of some...... description of these codes in terms of order domains has been found. In my talk I will indicate how one can use the ideas behind the order bound to obtain a lower bound for the minimum distance of any AG-code. After this I will compare this generalized order bound with other known lower bounds...

  1. Mass size distribution of particle-bound water

    Science.gov (United States)

    Canepari, S.; Simonetti, G.; Perrino, C.

    2017-09-01

    The thermal-ramp Karl-Fisher method (tr-KF) for the determination of PM-bound water has been applied to size-segregated PM samples collected in areas subjected to different environmental conditions (protracted atmospheric stability, desert dust intrusion, urban atmosphere). This method, based on the use of a thermal ramp for the desorption of water from PM samples and the subsequent analysis by the coulometric KF technique, had been previously shown to differentiate water contributes retained with different strength and associated to different chemical components in the atmospheric aerosol. The application of the method to size-segregated samples has revealed that water showed a typical mass size distribution in each one of the three environmental situations that were taken into consideration. A very similar size distribution was shown by the chemical PM components that prevailed during each event: ammonium nitrate in the case of atmospheric stability, crustal species in the case of desert dust, road-dust components in the case of urban sites. The shape of the tr-KF curve varied according to the size of the collected particles. Considering the size ranges that better characterize the event (fine fraction for atmospheric stability, coarse fraction for dust intrusion, bi-modal distribution for urban dust), this shape is coherent with the typical tr-KF shape shown by water bound to the chemical species that predominate in the same PM size range (ammonium nitrate, crustal species, secondary/combustion species - road dust components).

  2. Hybridization thermodynamics of DNA bound to gold nanoparticles

    International Nuclear Information System (INIS)

    Lang, Brian

    2010-01-01

    Isothermal Titration Calorimetry (ITC) was used to study the thermodynamics of hybridization on DNA-functionalized colloidal gold nanoparticles. When compared to the thermodynamics of hybridization of DNA that is free in solution, the differences in the values of the Gibbs free energy of reaction, Δ r G o , the enthalpy, Δ r H o , and entropy, Δ r S o , were small. The change in Δ r G o between the free and bound states was always positive but with statistical significance outside the 95% confidence interval, implying the free DNA is slightly more stable than when in the bound state. Additionally, ITC was also able to reveal information about the binding stoichiometry of the hybridization reactions on the DNA-functionalized gold nanoparticles, and indicates that there is a significant fraction of the DNA on gold nanoparticle surface that is unavailable for DNA hybridization. Furthermore, the fraction of available DNA is dependent on the spacer group on the DNA that is used to span the gold surface from that to the probe DNA.

  3. Structure of Escherichia coli Hfq bound to polyriboadenylate RNA

    DEFF Research Database (Denmark)

    Link, Todd M; Valentin-Hansen, Poul; Brennan, Richard G

    2009-01-01

    (A) RNA, A(15). The structure reveals a unique RNA binding mechanism. Unlike uridine-containing sequences, which bind to the "proximal" face, the poly(A) tract binds to the "distal" face of Hfq using 6 tripartite binding motifs. Each motif consists of an adenosine specificity site (A site), which......Hfq is a small, highly abundant hexameric protein that is found in many bacteria and plays a critical role in mRNA expression and RNA stability. As an "RNA chaperone," Hfq binds AU-rich sequences and facilitates the trans annealing of small RNAs (sRNAs) to their target mRNAs, typically resulting...... in the down-regulation of gene expression. Hfq also plays a key role in bacterial RNA decay by binding tightly to polyadenylate [poly(A)] tracts. The structural mechanism by which Hfq recognizes and binds poly(A) is unknown. Here, we report the crystal structure of Escherichia coli Hfq bound to the poly...

  4. Transcriptome of E. coli K1 bound to human brain microvascular endothelial cells

    OpenAIRE

    Xie, Yi; Parthasarathy, Geetha; Di Cello, Francescopaolo; Teng, Ching-Hao; Paul-Satyaseela, Maneesh; Kim, Kwang Sik

    2007-01-01

    Escherichia coli K1 is the most common Gram-negative organism causing neonatal meningitis. Binding to human brain microvascdular endothelial cells (HBMEC) is an essential step for E. coli K1 traversal of the blood-brain barrier. In this study, we examined expression profiles of E. coli K1 strain RS218 during its binding to HBMEC. Comparison of HBMEC-bound E. coli K1 with collagen-bound E. coli revealed more than one hundred genes whose expression patterns were significantly changed in HBMEC-b...

  5. Derivation of upper bound concentration of LLW for land disposal in Taiwan

    International Nuclear Information System (INIS)

    Chang, F.D.; Liou, C.T.; Su, M.F.; Tsai, S.C.

    1989-01-01

    The upper bound concentrations of radionuclides in the low level waste to be disposed in Taiwan are investigated based on a proposed reference site with all of the scenarios and exposure pathways reflecting the local conditions and environmental characteristics. The analysis reveals that most of the upper bound concentrations are determined from the scenario of intruder-agriculture. It can also be found that the Transuranic radionuclides and those with long half-lives are the dominant radionuclides which result in major radiological impact to the environment in this intruder-agriculture scenario

  6. OPRA capacity bounds for selection diversity over generalized fading channels

    KAUST Repository

    Hanif, Muhammad Fainan; Yang, Hongchuan; Alouini, Mohamed-Slim

    2014-01-01

    , lower and upper bounds on OPRA capacity for selection diversity scheme are presented. These bounds hold for variety of fading channels including log-normal and generalized Gamma distributed models and have very simple analytic expressions for easy

  7. Bounded Perturbation Regularization for Linear Least Squares Estimation

    KAUST Repository

    Ballal, Tarig; Suliman, Mohamed Abdalla Elhag; Al-Naffouri, Tareq Y.

    2017-01-01

    This paper addresses the problem of selecting the regularization parameter for linear least-squares estimation. We propose a new technique called bounded perturbation regularization (BPR). In the proposed BPR method, a perturbation with a bounded

  8. Bound values for Hall conductivity of heterogeneous medium under ...

    Indian Academy of Sciences (India)

    - ditions in inhomogeneous medium has been studied. It is shown that bound values for. Hall conductivity differ from bound values for metallic conductivity. This is due to the unusual character of current percolation under quantum Hall effect ...

  9. A versatile strategy towards non-covalent functionalization of graphene by surface-confined supramolecular self-assembly of Janus tectons

    Directory of Open Access Journals (Sweden)

    Ping Du

    2015-03-01

    Full Text Available Two-dimensional (2D, supramolecular self-assembly at surfaces is now well-mastered with several existing examples. However, one remaining challenge to enable future applications in nanoscience is to provide potential functionalities to the physisorbed adlayer. This work reviews a recently developed strategy that addresses this key issue by taking advantage of a new concept, Janus tecton materials. This is a versatile, molecular platform based on the design of three-dimensional (3D building blocks consisting of two faces linked by a cyclophane-type pillar. One face is designed to steer 2D self-assembly onto C(sp2-carbon-based flat surfaces, the other allowing for the desired functionality above the substrate with a well-controlled lateral order. In this way, it is possible to simultaneously obtain a regular, non-covalent paving as well as supramolecular functionalization of graphene, thus opening interesting perspectives for nanoscience applications.

  10. The preparation of highly water-soluble multi-walled carbon nanotubes by irreversible noncovalent functionalization with a pyrene-carrying polymer

    International Nuclear Information System (INIS)

    Xue Chaohua; Zhou Renjia; Shi Minmin; Gao Yan; Wu Gang; Chen Hongzheng; Wang Mang; Zhang Xiaobin

    2008-01-01

    Multi-walled carbon nanotubes (MWNTs) have been solubilized in water via a noncovalent method of exfoliation and centrifugation cycles with the assistance of hydrolyzed poly(styrene-co-maleic anhydride) carrying pyrene (HPSMAP). After the obtained solution was micro-filtered and dried, a water-soluble complex of HPSMAP-MWNTs was obtained. The solubility of HPSMAP-MWNTs was measured to be 46.2 mg ml -1 with a net MWNT concentration of 7.4 mg ml -1 in water. Thermal gravimetric analyses showed that there was a large amount of polymer remaining on the surface of MWNTs irreversibly after thoroughly removing the free polymer. Other characterizations using transmission electron microscopy, Fourier transform infrared (FTIR) spectroscopy, fluorescence spectra, and fluorescence decay were conducted

  11. Fabrication and non-covalent modification of highly oriented thin films of a zeolite-like metal-organic framework (ZMOF) with rho topology

    KAUST Repository

    Shekhah, Osama

    2015-01-01

    Here we report the fabrication of the first thin film of a zeolite-like metal-organic framework (ZMOF) with rho topology (rho-ZMOF-1, ([In48(HImDC)96]48-)n) in a highly oriented fashion on a gold-functionalized substrate. The oriented rho-ZMOF-1 film was functionalized by non-covalent modification via post-synthetic exchange of different probe molecules, such as acridine yellow, methylene blue, and Nile red. In addition, encapsulation of a porphyrin moiety was achieved via in situ synthesis and construction of the rho-ZMOF. Adsorption kinetics of volatile organic compounds on rho-ZMOF-1 thin films was also investigated. This study suggests that rho-ZMOF-1 thin films can be regarded as a promising platform for various applications such as sensing and catalysis. This journal is

  12. Bound states of Θ+ in nuclei

    International Nuclear Information System (INIS)

    Oset, E.; Cabrera, D.; Li, Q.B.; Magas, V.K.; Vicente Vacas, M.J.

    2005-01-01

    We study the binding energy and the width of the Θ + in nuclei, associated to the KN and KπN components. The first one leads to negligible contributions while the second one leads to a sizeable attraction, enough to bind the Θ + in nuclei. Pauli blocking and binding effects on the KN decay reduce considerably the Θ + decay width in nuclei and medium effects associated to the KπN component also lead to a very small width, as a consequence of which one finds separation between the bound levels considerably larger than the width of the states

  13. Fermionic bound states in distinct kinklike backgrounds

    Energy Technology Data Exchange (ETDEWEB)

    Bazeia, D. [Universidade Federal da Paraiba, Departamento de Fisica, Joao Pessoa, Paraiba (Brazil); Mohammadi, A. [Universidade Federal de Campina Grande, Departamento de Fisica, Caixa Postal 10071, Campina Grande, Paraiba (Brazil)

    2017-04-15

    This work deals with fermions in the background of distinct localized structures in the two-dimensional spacetime. Although the structures have a similar topological character, which is responsible for the appearance of fractionally charged excitations, we want to investigate how the geometric deformations that appear in the localized structures contribute to the change in the physical properties of the fermionic bound states. We investigate the two-kink and compact kinklike backgrounds, and we consider two distinct boson-fermion interactions, one motivated by supersymmetry and the other described by the standard Yukawa coupling. (orig.)

  14. Quarks as quasiparticles of bound states

    International Nuclear Information System (INIS)

    Tyapkin, A.A.

    1977-01-01

    Interpretation of quarks as strongly bound subsystems of the baryon structure, being in various states with integer the quantum numbers Q and B, is considered. Three original quark states, distinguished by Q, B, and J, are unambiguously determined from the condition that the quarks have the corresponding fractional quantum numbers while the integer quantum numbers for the whole system are known. With this in view the new quantum number ''colour'' is interpreted as a quantity, specifying the appearance of the subsystems in various eigen-states. Basing on the generalized Sakata model, the self-consistency of change of the colour states in the three-quark system is explained

  15. Magnetic moment of a bound electron

    CERN Document Server

    Czarnecki, Andrzej; Mondejar, Jorge; Piclum, Jan H

    2010-01-01

    Theoretical predictions underlying determinations of the fine structure constant alpha and the electron-to-proton mass ratio m_e/m_p are reviewed, with the emphasis on the bound electron magnetic anomaly g-2. The theory of the interaction of hydrogen-like ions with a magnetic field is discussed. The status of efforts aimed at the determination of O(alpha (Z alpha)^5) and O(alpha^2 (Z alpha)^5) corrections to the g factor is presented. The reevaluation of analogous corrections to the Lamb shift and the hyperfine splitting is summarized.

  16. Andreev bound states. Some quasiclassical reflections

    International Nuclear Information System (INIS)

    Lin, Y.; Leggett, A. J.

    2014-01-01

    We discuss a very simple and essentially exactly solvable model problem which illustrates some nice features of Andreev bound states, namely, the trapping of a single Bogoliubov quasiparticle in a neutral s-wave BCS superfluid by a wide and shallow Zeeman trap. In the quasiclassical limit, the ground state is a doublet with a splitting which is proportional to the exponentially small amplitude for “normal” reflection by the edges of the trap. We comment briefly on a prima facie paradox concerning the continuity equation and conjecture a resolution to it

  17. Andreev bound states. Some quasiclassical reflections

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Y., E-mail: yiriolin@illinois.edu; Leggett, A. J. [University of Illinois at Urhana-Champaign, Dept. of Physics (United States)

    2014-12-15

    We discuss a very simple and essentially exactly solvable model problem which illustrates some nice features of Andreev bound states, namely, the trapping of a single Bogoliubov quasiparticle in a neutral s-wave BCS superfluid by a wide and shallow Zeeman trap. In the quasiclassical limit, the ground state is a doublet with a splitting which is proportional to the exponentially small amplitude for “normal” reflection by the edges of the trap. We comment briefly on a prima facie paradox concerning the continuity equation and conjecture a resolution to it.

  18. Uniformly bounded representations of the Lorentz groups

    International Nuclear Information System (INIS)

    Brega, A.O.

    1982-01-01

    For the Lorentz group G = SO/sub e/(n + 1, 1)(ngreater than or equal to 2) the author constructs a family of uniformly bounded representations by means of analytically continuing a certain normalization of the unitary principal series. The method the author uses relies on an analysis of various operators under a Mellin transform and extends earlier work of E.N. Wilson. In a series of papers Kunze and Stein initiated the theory of uniformly bounded representations of semisimple Lie groups; the starting point is the unitary principal series T(sigma,s) obtained in a certain subgroup M of G and a purely imaginary number s. From there Kunze and Stein constructed families of representations R(sigma,s) depending analytically on a parameter s in a domain D of C containing the imaginary axis which are unitarily equilvalent to T(sigma,s) for s contained in the set of imaginary numbers and whose operator norms are uniformly bounded for each s in D. In the case of the Lorentz groups SO/sub e/(n + 1, 1)(ngreater than or equal to2) and the trivial representation 1 of M, E.N. Wilson obtained such a family R(1,s) for the domain D = [s contained in the set of C: absolute value Re(s) Vertical Bar2]. For this domain D and for any representation sigma of M the author provides a family R(sigma,s) of uniformly bounded representations analytically continuing T(sigma,s), thereby generalizing Wilson's work. The author has also investigated certain symmetry properties of the representations R(sigma,s) under the action of the Weyl group. The trivial representation is Weyl group invariant and the family R(1,s) obtained by Wilson satisfies R(1,s) = R(1,-s) reflecting this. Obtained was the analogous result R(sigma,s) = R(sigma,-s) for some well known representations sigma that are Weyl group invariant. This involves the explicit computation of certain constants arising in the Fourier transforms of intertwining operators

  19. BOUND PERIODICAL HOLDINGS BATTELLE - NORTHWEST LIBRARY

    Energy Technology Data Exchange (ETDEWEB)

    None

    1967-05-01

    This report lists the bound periodicals in the Technical Library at the Pacific Northwest Laboratory, operated by Battelle Memorial Institute. It was prepared from a computer program and is arranged in two parts. Part one is an alphabetical list of journals by title; part two is an arrangement of the journals by subject. The list headings are self-explanatory, with the exception of the title code, which is necessary in the machine processing. The listing is complete through June, 1966 and updates an earlier publication issued in March, 1965.

  20. Total-variation regularization with bound constraints

    International Nuclear Information System (INIS)

    Chartrand, Rick; Wohlberg, Brendt

    2009-01-01

    We present a new algorithm for bound-constrained total-variation (TV) regularization that in comparison with its predecessors is simple, fast, and flexible. We use a splitting approach to decouple TV minimization from enforcing the constraints. Consequently, existing TV solvers can be employed with minimal alteration. This also makes the approach straightforward to generalize to any situation where TV can be applied. We consider deblurring of images with Gaussian or salt-and-pepper noise, as well as Abel inversion of radiographs with Poisson noise. We incorporate previous iterative reweighting algorithms to solve the TV portion.

  1. Bound Alternative Direction Optimization for Image Deblurring

    Directory of Open Access Journals (Sweden)

    Xiangrong Zeng

    2014-01-01

    the ℓp regularizer by a novel majorizer and then, based on a variable splitting, to reformulate the bound unconstrained problem into a constrained one, which is then addressed via an augmented Lagrangian method. The proposed algorithm actually combines the reweighted ℓ1 minimization method and the alternating direction method of multiples (ADMM such that it succeeds in extending the application of ADMM to ℓp minimization problems. The conducted experimental studies demonstrate the superiority of the proposed algorithm for the synthesis ℓp minimization over the state-of-the-art algorithms for the synthesis ℓ1 minimization on image deblurring.

  2. Lower bound on inconclusive probability of unambiguous discrimination

    International Nuclear Information System (INIS)

    Feng Yuan; Zhang Shengyu; Duan Runyao; Ying Mingsheng

    2002-01-01

    We derive a lower bound on the inconclusive probability of unambiguous discrimination among n linearly independent quantum states by using the constraint of no signaling. It improves the bound presented in the paper of Zhang, Feng, Sun, and Ying [Phys. Rev. A 64, 062103 (2001)], and when the optimal discrimination can be reached, these two bounds coincide with each other. An alternative method of constructing an appropriate measurement to prove the lower bound is also presented

  3. Thermodynamic Upper Bound on Broadband Light Coupling with Photonic Structures

    KAUST Repository

    Yu, Zongfu; Raman, Aaswath; Fan, Shanhui

    2012-01-01

    to an upper bound dictated by the second law of thermodynamics. Such bound limits how efficient light can be coupled to any photonic structure. As one example of application, we use this upper bound to derive the limit of light absorption in broadband solar

  4. Bounds on the capacity of constrained two-dimensional codes

    DEFF Research Database (Denmark)

    Forchhammer, Søren; Justesen, Jørn

    2000-01-01

    Bounds on the capacity of constrained two-dimensional (2-D) codes are presented. The bounds of Calkin and Wilf apply to first-order symmetric constraints. The bounds are generalized in a weaker form to higher order and nonsymmetric constraints. Results are given for constraints specified by run-l...

  5. Bounded Rationality, Retaliation, and the Spread of Urban Violence

    Science.gov (United States)

    Jacobs, Bruce A.; Wright, Richard

    2010-01-01

    Drawing from in-depth interviews with 52 active street criminals, this article examines the grounded theoretic implications of bounded rationality for retaliatory street violence. The bounds on rationality that this article explores are anger, uncertainty, and time pressure. These bounds create imperfections in the retaliatory decision-making…

  6. Di- or polysulphide-bound biomarkers in sulphur-rich geomacromolecules as revealed by selective chemolysis

    NARCIS (Netherlands)

    Sinninghe Damsté, J.S.; Kohnen, M.E.L.; Kock-van Dalen, A.C.; Leeuw, J.W. de

    1991-01-01

    Three types of sulphur-rich, high-molecular-weight material in the alkylsulphide, the polar and the asphaltene fracions isolated from the bitumen of an immature bituminous shale from the Vena del Gesso basin (Italy) were desulphurised.

  7. Bounded dust-acoustic waves in a cylindrically bounded collisional dusty plasma with dust charge variation

    International Nuclear Information System (INIS)

    Wei Nanxia; Xue Jukui

    2006-01-01

    Taking into account the boundary, particle collisions, and dust charging effects, dust-acoustic waves in a uniform cylindrically bounded dusty plasma is investigated analytically, and the dispersion relation for the dust-acoustic wave is obtained. The effects of boundary, dust charge variation, particle collision, and dust size on the dust-acoustic wave are discussed in detail. Due to the bounded cylindrical boundary effects, the radial wave number is discrete, i.e., the spectrum is discrete. It is shown that the discrete spectrum, the adiabatic dust charge variation, dust grain size, and the particle collision have significant effects on the dust-acoustic wave

  8. Effect of uniaxial stress on free and bismuth-bound excitons in InP

    International Nuclear Information System (INIS)

    Weber, G.; Ruehle, W.

    1979-01-01

    The reduction of the shear deformation potentials of holes bound to the isoelectronic impurity Bi in InP is determined by piezoluminescence. It is compared with the corresponding reduction for holes bound to the Coulomb-type acceptors C and Zn. The theory for an effective mass acceptor describes well the cases of C and Zn. However, additional effects as local strain and Stark fields must be involved in the case of Bi leading to an extremely large reduction of the deformation potentials. No change in binding energy with applied stress as well as no exchange splitting of the Bi-bound exciton can be detected within experimental accuracy. The stress dependence of the free exciton reflectance reveals values for the band deformation potentials and a value of 0.07 meV for the exchange splitting of the free exciton in InP. (author)

  9. A Branch and Bound Algorithm for a Class of Biobjective Mixed Integer Programs

    DEFF Research Database (Denmark)

    Stidsen, Thomas Riis; Andersen, Kim Allan; Dammann, Bernd

    2014-01-01

    there is the complicating factor that some of the variables are required to be integral. The resulting class of problems is named multiobjective mixed integer programming (MOMIP) problems. Solving these kinds of optimization problems exactly requires a method that can generate the whole set of nondominated points (the...... Pareto-optimal front). In this paper, we first give a survey of the newly developed branch and bound methods for solving MOMIP problems. After that, we propose a new branch and bound method for solving a subclass of MOMIP problems, where only two objectives are allowed, the integer variables are binary......, and one of the two objectives has only integer variables. The proposed method is able to find the full set of nondominated points. It is tested on a large number of problem instances, from six different classes of MOMIP problems. The results reveal that the developed biobjective branch and bound method...

  10. Analytic quantum bounds on Bell inequalities

    International Nuclear Information System (INIS)

    Filipp, S.; Svozil, K.

    2005-01-01

    Full text: Can realism be combined with the quantum world? An important tool to investigate in this question are Bell's inequalities and violations thereof - they represent a cornerstone of our present understanding of quantum mechanics and therefore the description of nature. Here we present a simple algebraic method to calculate violations for any measurement arrangements that are maximal in the sense that quantum mechanics does not allow a stronger violation. Having two or more polarization analyzers available and a source producing photon-pairs in arbitrary polarization states Bell-type inequalities tell us which probabilities for measuring the polarization in particular directions are viable in a deterministic theory. Quantum mechanics does not obey these rules, but yields a violation of these inequalities. The questions is to what extent the inequalities are violated. Making use of a min-max principle analytical expressions can be found for the 'fine structure' of the maximal violations of arbitrary Bell-like inequalities, i. e. the upper bound reachable by any state when the analyzers measure in given directions. Knowing these bounds is useful for experimental tests of the validity of quantum mechanics and can serve as a prerequisite to answer the even more pressing question, why no stronger violation has been observed until now. (author)

  11. Electromagnetic structure of a bound nucleon

    International Nuclear Information System (INIS)

    Nogami, Y.

    1977-01-01

    The effect of binding on the electromagnetic (e.m.) structure of a nucleon in a nucleus is examined by means of a model consisting of a single nucleon which is bound in a harmonic oscillator potential and also coupled to the pion field through the Chew-Low interaction. The 'two-pion contribution' to the e.m. structure is considered. This is the part which is probably most susceptible to the binding effect. By the binding effect it is meant the one which arises because the nucleon wave functions, in the intermediate state as well as in the initial and final states, are distorted by the potential in which the nucleon is bound. This may be compared to a similar correction to the impulse approximation for pion-nucleus scattering. Unlike the latter which is likely to be quite appreciable, the binding correction to the e.m. structure of the nucleon is found to be negligibly small. The so-called quenching effect due to the Pauli principle when there are other nucleons is also discussed [pt

  12. Dynamic bounds coupled with Monte Carlo simulations

    Energy Technology Data Exchange (ETDEWEB)

    Rajabalinejad, M., E-mail: M.Rajabalinejad@tudelft.n [Faculty of Civil Engineering, Delft University of Technology, Delft (Netherlands); Meester, L.E. [Delft Institute of Applied Mathematics, Delft University of Technology, Delft (Netherlands); Gelder, P.H.A.J.M. van; Vrijling, J.K. [Faculty of Civil Engineering, Delft University of Technology, Delft (Netherlands)

    2011-02-15

    For the reliability analysis of engineering structures a variety of methods is known, of which Monte Carlo (MC) simulation is widely considered to be among the most robust and most generally applicable. To reduce simulation cost of the MC method, variance reduction methods are applied. This paper describes a method to reduce the simulation cost even further, while retaining the accuracy of Monte Carlo, by taking into account widely present monotonicity. For models exhibiting monotonic (decreasing or increasing) behavior, dynamic bounds (DB) are defined, which in a coupled Monte Carlo simulation are updated dynamically, resulting in a failure probability estimate, as well as a strict (non-probabilistic) upper and lower bounds. Accurate results are obtained at a much lower cost than an equivalent ordinary Monte Carlo simulation. In a two-dimensional and a four-dimensional numerical example, the cost reduction factors are 130 and 9, respectively, where the relative error is smaller than 5%. At higher accuracy levels, this factor increases, though this effect is expected to be smaller with increasing dimension. To show the application of DB method to real world problems, it is applied to a complex finite element model of a flood wall in New Orleans.

  13. More loosely bound hadron molecules at CDF?

    CERN Document Server

    Bignamini, C; Piccinini, F; Polosa, A D; Riquer, V; Sabelli, C

    2010-01-01

    In a recent paper we have proposed a method to estimate the prompt production cross section of X(3872) at the Tevatron assuming that this particle is a loosely bound molecule of a D and a D*bar meson. Under this hypothesis we find that it is impossible to explain the high prompt production cross section found by CDF at sigma(X(3872)) \\sim 30-70 nb as our theoretical prediction is about 300 times smaller than the measured one. Following our work, Artoisenet and Braaten, have suggested that final state interactions in the DD*bar system might be so strong to push the result we obtained for the cross section up to the experimental value. Relying on their conclusions we show that the production of another very narrow loosely bound molecule, the X_s=D_s D_s*bar, could be similarly enhanced. X_s should then be detectable at CDF with a mass of 4080 MeV and a prompt production cross section of sigma(X_s) \\sim 1-3 nb.

  14. Generalized bounds for convex multistage stochastic programs

    CERN Document Server

    Künzi, H; Fandel, G; Trockel, W; Basile, A; Drexl, A; Dawid, H; Inderfurth, K; Kürsten, W; Schittko, U

    2005-01-01

    This work was completed during my tenure as a scientific assistant and d- toral student at the Institute for Operations Research at the University of St. Gallen. During that time, I was involved in several industry projects in the field of power management, on the occasion of which I was repeatedly c- fronted with complex decision problems under uncertainty. Although usually hard to solve, I quickly learned to appreciate the benefit of stochastic progr- ming models and developed a strong interest in their theoretical properties. Motivated both by practical questions and theoretical concerns, I became p- ticularly interested in the art of finding tight bounds on the optimal value of a given model. The present work attempts to make a contribution to this important branch of stochastic optimization theory. In particular, it aims at extending some classical bounding methods to broader problem classes of practical relevance. This book was accepted as a doctoral thesis by the University of St. Gallen in June 2004.1...

  15. Phenomenological bounds in inclusive neutrino interactions

    International Nuclear Information System (INIS)

    Aubrecht, G.J. II; Takasugi, E.; Tanaka, K.

    1975-01-01

    Using expressions for the ν and anti ν charged and neutral current cross sections and the electroproduction structure function integral and positivity requirements of the sea contribution, bounds are obtained on sigma/sup anti nu N//sigma/sup anti nu N/, and sigma/sup anti nu N//sub nc//sigma/sup nu N//sub nc/ in the standard model. A bound on sigma/sup anti nu N//sigma/sup nu N/ obtained with a V + A term anti p'γ/sub mu/(1-γ 5 )n is used to rule out such a term in the current. A plot of sigma/sup nu N//sub nc/ + sigma/sup anti nu N//sub nc/ versus sigma/sup nu N//sub nc/ - sigma/sup anti nu N//sub nc/ is introduced to analyze the neutral current data. A new relation connecting moments of y and y distributions at a particular point y/sub n/ for ν and anti ν interactions is found. The results do not depend on the neutral current data

  16. Search for a bound K− pp system

    Directory of Open Access Journals (Sweden)

    Camerini P.

    2010-04-01

    Full Text Available Data from the K− absorption reaction on 6,7Li, 9Be, 13C and 16O have recently been collected by FINUDA at the DAΦNE φ-factory (Laboratori Nazionali di Frascati-INFN, following an earlier lower statitics run on 12C and some other targets. FINUDA is a high acceptance magnetic spectrometer which performed a wide range of studies by detecting the charged particles and neutrons exiting the targets after the absorption event. In this paper it is discussed about the study of the A(K− , Λp reaction in the context of the search for deeply bound $ar{K}$ - nuclear states. The observation of a bump in the Λp invariant mass distribution is discussed in terms of a possible signature of a deeply bound K− pp kaonic cluster as well as of more conventional physics. An overview of the experimental situation in this field will be given.

  17. New Insights into the Functional Behavior of Antibodies as Revealed by Binding Studies on an Anti-Uranium Monoclonal Antibody

    International Nuclear Information System (INIS)

    Blake, Diane A.; Xia Li; Haini Yu; Blake, Robert C.

    2004-01-01

    As part of an ongoing effort to develop immunoassays for chelated uranium(VI) on a hand-held flow fluorimeter, an anti-uranium monoclonal antibody designated as 8A11 was fluorescently labeled using two different strategies. When 8A11 was coupled via reactive lysines to either ALEXATM 488 or Cy5TM, the resulting fluorescent antibody conjugate exhibited positive cooperativity in the presence of its antigen, U(VI) chelated with 2,9-dicarboxy-1,10-phenanthroline (U(VI)-DCP). That is, when one of the two binding sites on the covalently modified 8A11 was occupied with bound antigen, the affinity of the remaining site on the antibody for U(VI)-DCP appeared to increase. Unmodified 8A11 bound U(VI)-DCP with the expected hyperbolic dependence on the concentration of antigen, consistent with independent and equal binding of ligand at both sites. Proteolytic cleavage of the fluorescently conjugated 8A11 to produce the fluorescent monovalent Fab fragment yielded an active preparation that now bound U(VI)-DCP with no evidence of positive cooperativity. Although, in principle, any divalent antibody has the potential to exhibit positive cooperativity in its binding interactions with its antigen, very little literature precedent for this type of behavior exists. Native 8A11 was also noncovalently labeled with highly fluorescent ZENONTM reagents. These reagents are fluorescently-labeled Fab fragments of goat anti-mouse antibodies that bind to the Fc portion of 8A11. These high-affinity, monovalent fluorescent reagents permitted the intact 8A11 mouse antibody to be labeled in situ with no covalent modifications. Incubation of the 8A11 with ZENON 647 produced a fluorescent protein complex that showed an 8-fold higher affinity for U(VI)-DCP than did the free 8A11 alone. Again, very few literature precedents exist for this phenomenon, where agents that bind to the Fc portion of an intact antibody change the affinity of the antibody for the antigen at the structurally distant Fab portion

  18. USE OF BOUNDING ANALYSES TO ESTIMATE THE PREFORMANCE OF A SEISMICALLY ISOLATED STRUCTURE

    Directory of Open Access Journals (Sweden)

    Gökhan ÖZDEMİR

    2017-03-01

    Full Text Available Current design approach for seismic isolated structures is to perform bounding analyses. These analyses provide an envelope for the response of the seismic isolated structure rather than focusing on the actual performance. In this study, the success of bounding analyses to estimate performance of a seismic isolated structure, in which the isolation is provided by means of lead rubber bearings (LRBs, is evaluated in a comparative manner. For this purpose, nonlinear response history analyses were performed under the effect of bidirectional ground motion excitations. In bounding analyses, non-deteriorating hysteretic representations were used to model the hysteretic behavior of LRBs. On the other hand, to estimate the actual performance of both the superstructure and isolator units, deteriorating hysteretic idealizations were employed. The deterioration in strength of LRBs was defined as a function of temperature rise in the lead core. The analyzed structure is an existing seismically isolated hospital building and analytically modeled in accordance with its reported design properties for both isolation units and superstructure. Results obtained from analyses where LRBs are idealized by both deteriorating and non-deteriorating hysteretic representations are used in the comparisons. The response quantities used in the comparisons are maximum isolator displacement, maximum isolator force, maximum absolute floor acceleration, and maximum relative story displacements. In an average sense, bounding analyses is found to provide conservative estimates for the selected response quantities and fulfills its intended purpose. However, it is revealed that there may be individual cases where bounding analyses fails to provide a safe envelope.

  19. Experimental and theoretical study of bound and quasibound states of Ce{sup -}

    Energy Technology Data Exchange (ETDEWEB)

    Walter, C. W.; Gibson, N. D.; Li, Y.-G.; Matyas, D. J.; Alton, R. M.; Lou, S. E.; Field, R. L. III; Hanstorp, D.; Pan, Lin; Beck, Donald R. [Department of Physics and Astronomy, Denison University, Granville, Ohio 43023 (United States); Department of Physics, University of Gothenburg, SE-412 96 Gothenburg (Sweden); Department of Physics, Michigan Technological University, Houghton, Michigan 49931 (United States)

    2011-09-15

    The negative ion of cerium is investigated experimentally with tunable infrared laser photodetachment spectroscopy and theoretically with relativistic configuration interaction in the continuum formalism. The relative cross section for neutral atom production is measured with a crossed ion-beam-laser-beam apparatus over the photon energy range of 0.54-0.75 eV. A rich resonance spectrum is revealed near the threshold with, at least, 12 peaks observed due to transitions from bound states of Ce{sup -} to either bound or quasibound excited states of the negative ion. Theoretical calculations of the photodetachment cross sections enable identification of the transitions responsible for the measured peaks. Two of the peaks are due to electric dipole-allowed bound-bound transitions in Ce{sup -}, making cerium only the second atomic negative ion that has been demonstrated to support multiple bound states of opposite parity. In addition, combining the experimental data with the theoretical analysis determines the electron affinity of cerium to be 0.628(10) eV and the fine structure splitting of the ground state of Ce{sup -} ({sup 4} H{sub 7/2}-{sup 4} H{sub 9/2}) to be 0.097 75(4) eV.

  20. Reducing Conservatism of Analytic Transient Response Bounds via Shaping Filters

    Science.gov (United States)

    Kwan, Aiyueh; Bedrossian, Nazareth; Jan, Jiann-Woei; Grigoriadis, Karolos; Hua, Tuyen (Technical Monitor)

    1999-01-01

    Recent results show that the peak transient response of a linear system to bounded energy inputs can be computed using the energy-to-peak gain of the system. However, analytically computed peak response bound can be conservative for a class of class bounded energy signals, specifically pulse trains generated from jet firings encountered in space vehicles. In this paper, shaping filters are proposed as a Methodology to reduce the conservatism of peak response analytic bounds. This Methodology was applied to a realistic Space Station assembly operation subject to jet firings. The results indicate that shaping filters indeed reduce the predicted peak response bounds.

  1. Degenerate quantum codes and the quantum Hamming bound

    International Nuclear Information System (INIS)

    Sarvepalli, Pradeep; Klappenecker, Andreas

    2010-01-01

    The parameters of a nondegenerate quantum code must obey the Hamming bound. An important open problem in quantum coding theory is whether the parameters of a degenerate quantum code can violate this bound for nondegenerate quantum codes. In this article we show that Calderbank-Shor-Steane (CSS) codes, over a prime power alphabet q≥5, cannot beat the quantum Hamming bound. We prove a quantum version of the Griesmer bound for the CSS codes, which allows us to strengthen the Rains' bound that an [[n,k,d

  2. Tight bounds on computing error-correcting codes by bounded-depth circuits with arbitrary gates

    Czech Academy of Sciences Publication Activity Database

    Gál, A.; Hansen, A. K.; Koucký, Michal; Pudlák, Pavel; Viola, E.

    2013-01-01

    Roč. 59, č. 10 (2013), s. 6611-6627 ISSN 0018-9448 R&D Projects: GA AV ČR IAA100190902 Institutional support: RVO:67985840 Keywords : bounded-depth circuits * error-correcting codes * hashing Subject RIV: BA - General Mathematics Impact factor: 2.650, year: 2013 http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6578188

  3. Tight bounds on computing error-correcting codes by bounded-depth circuits with arbitrary gates

    Czech Academy of Sciences Publication Activity Database

    Gál, A.; Hansen, A. K.; Koucký, Michal; Pudlák, Pavel; Viola, E.

    2013-01-01

    Roč. 59, č. 10 (2013), s. 6611-6627 ISSN 0018-9448 R&D Projects: GA AV ČR IAA100190902 Institutional support: RVO:67985840 Keywords : bounded-depth circuits * error -correcting codes * hashing Subject RIV: BA - General Mathematics Impact factor: 2.650, year: 2013 http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6578188

  4. Structure and dynamics of weakly bound complexes

    International Nuclear Information System (INIS)

    Skouteris, D.

    1998-01-01

    The present thesis deals with the spectroscopic and theoretical investigation of weakly bound complexes involving a methane molecule. Studies of these Van der Waals complexes can give valuable information on the relevant intermolecular dynamics and promote the understanding of the interactions between molecules (which can ultimately lead to chemical reactions). Especially interesting are complexes involving molecules of high symmetry (e.g. tetrahedral, such as methane) because of the unusual effects arising from it (selection rules, nuclear Spin statistical weights etc.). The infrared spectrum of the Van der Waals complex between a CH 4 and a N 2 O molecule has been recorded and most of it has been assigned in the region of the N - O stretch (approximately 2225.0 cm -1 ). Despite the fact that this is really a weakly bound complex, it is nevertheless rigid enough so that the standard model for asymmetric top spectra can be applied to it with the usual quantum numbers. From the value of the inertial defect, it turns out that the methane unit is locked in a rigid configuration within the complex rather than freely rotating. The intermolecular distance as well as the tilting angle of the N 2 O linear unit are determined from the rotational constants. The complex itself turns out to have a T - shaped configuration. The infrared spectrum of the Ar - CH 4 complex at the ν 4 (bending) band of methane is also assigned. This is different from the previous one in that the methane unit rotates almost freely Within the complex. As a result, the quantum numbers used to classify rovibrational energy levels include these of the free unit. The concept of 'overall symmetry' is made use of to rationalise selection rules in various sub-bands of the spectrum. Moreover, new terms in the potential anisotropy Hamiltonian are calculated through the use of the overall symmetry concept. These are termed 'mixed anisotropy' terms since they involve both rotational and vibrational degrees of

  5. Helioscope bounds on hidden sector photons

    International Nuclear Information System (INIS)

    Redondo, J.

    2008-01-01

    The flux of hypothetical ''hidden photons'' from the Sun is computed under the assumption that they interact with normal matter only through kinetic mixing with the ordinary standard model photon. Requiring that the exotic luminosity is smaller than the standard photon luminosity provides limits for the mixing parameter down to χ -14 , depending on the hidden photon mass. Furthermore, it is pointed point out that helioscopes looking for solar axions are also sensitive to hidden photons. The recent results of the CAST collaboration are used to further constrain the mixing parameter χ at low masses (m γ' <1 eV) where the luminosity bound is weaker. In this regime the solar hidden photon ux has a sizable contribution of longitudinally polarized hidden photons of low energy which are invisible for current helioscopes. (orig.)

  6. Frenetic Bounds on the Entropy Production

    Science.gov (United States)

    Maes, Christian

    2017-10-01

    We give a systematic derivation of positive lower bounds for the expected entropy production (EP) rate in classical statistical mechanical systems obeying a dynamical large deviation principle. The logic is the same for the return to thermodynamic equilibrium as it is for steady nonequilibria working under the condition of local detailed balance. We recover there recently studied "uncertainty" relations for the EP, appearing in studies about the effectiveness of mesoscopic machines. In general our refinement of the positivity of the expected EP rate is obtained in terms of a positive and even function of the expected current(s) which measures the dynamical activity in the system, a time-symmetric estimate of the changes in the system's configuration. Also underdamped diffusions can be included in the analysis.

  7. Bounded rational choice behaviour: applications in transport

    DEFF Research Database (Denmark)

    Jensen, Anders Fjendbo

    2016-01-01

    Even though the theory of rational behaviour has been challenged for almost 100 years, the dominant approach within the field of transport has been based upon the assumptions of neoclassical economics that we live in a world of rational decision makers who always have perfect knowledge and aim...... rational choice behaviour focuses on how the latter approach can be seriously taken into account within transport applications. As the editors discuss in the introduction, a true optimal choice can only be made if an individual has full and perfect information of all relevant attributes in his/her choice...... set. An individual is said to demonstrate bounded rational behaviour if he/she does not systematically consider all attributes deemed relevant for the decision problem at hand, does not consider all choice options and/or does not choose the best choice alternative. Such simplified representation...

  8. Diffraction scattering of strongly bound system

    International Nuclear Information System (INIS)

    Kuzmichev, V.E.

    1982-04-01

    The scattering of a hadron on a strongly bound system of two hadrons (dihadron) is considered in the high-energy limit for the relative hadron-dihadron motion. The dihadron scatterer motion and the internal interaction are included in our consideration. It is shown that only small values of the internal transfer momentum of dihadron particles bring the principal contribution to the three-particle propagator in eikonal approximation. On the basis of the exact analytical solution of the integral equation for the total Green function the scattering amplitude is derived. It is shown that the scattering amplitude contains only single, double, and triple scattering terms. The three new terms to the Glauber formula for the total cross section are obtained. These terms decrease both the true total hadron-hadron cross section and the screening correction. (orig.)

  9. Transient response in granular bounded heap flows

    Science.gov (United States)

    Xiao, Hongyi; Ottino, Julio M.; Lueptow, Richard M.; Umbanhowar, Paul B.

    2017-11-01

    Heap formation, a canonical granular flow, is common in industry and is also found in nature. Here, we study the transition between steady flow states in quasi-2D bounded heaps by suddenly changing the feed rate from one fixed value to another. During the transition, in both experiments and discrete element method simulations, an additional wedge of flowing particles propagates over the rising free surface. The downstream edge of the wedge - the wedge front - moves downstream with velocity inversely proportional to the square root of time. An additional longer duration transient process continues after the wedge front reaches the downstream wall. The transient flux profile during the entire transition is well modeled by a diffusion-like equation derived from local mass balance and a local linear relation between the flux and the surface slope. Scalings for the transient kinematics during the flow transitions are developed based on the flux profiles. Funded by NSF Grant CBET-1511450.

  10. Similarity problems and completely bounded maps

    CERN Document Server

    Pisier, Gilles

    2001-01-01

    These notes revolve around three similarity problems, appearing in three different contexts, but all dealing with the space B(H) of all bounded operators on a complex Hilbert space H. The first one deals with group representations, the second one with C* -algebras and the third one with the disc algebra. We describe them in detail in the introduction which follows. This volume is devoted to the background necessary to understand these three problems, to the solutions that are known in some special cases and to numerous related concepts, results, counterexamples or extensions which their investigation has generated. While the three problems seem different, it is possible to place them in a common framework using the key concept of "complete boundedness", which we present in detail. Using this notion, the three problems can all be formulated as asking whether "boundedness" implies "complete boundedness" for linear maps satisfying certain additional algebraic identities. Two chapters have been added on the HALMO...

  11. 'Critical' behaviour of weakly bound systems

    International Nuclear Information System (INIS)

    Lassaut, M.; Lombard, R.J.; Bulboaca, I.

    1995-11-01

    The class of 3-dimensional finite range or similar potentials λW(r) is discussed, depending on a strength constant λ. The behaviour of the eigenvalue E as function of λ-λ c is studied, where λ c is the critical value at the transition from 0 → 1 bound state. For the l=0 case, E α (λ-λ c ) 2 was found, whereas the relationship is linear for l≥1. Treating l as a continuous parameter in the radial Schroedinger equation, the evolution of the power-law between l=0 and l=1 is given. Besides spherically symmetric scalar potentials, the case of a repulsive scalar potential combined with a spin-orbit component of the Thomas form is also discussed. (author)

  12. Entanglement negativity bounds for fermionic Gaussian states

    Science.gov (United States)

    Eisert, Jens; Eisler, Viktor; Zimborás, Zoltán

    2018-04-01

    The entanglement negativity is a versatile measure of entanglement that has numerous applications in quantum information and in condensed matter theory. It can not only efficiently be computed in the Hilbert space dimension, but for noninteracting bosonic systems, one can compute the negativity efficiently in the number of modes. However, such an efficient computation does not carry over to the fermionic realm, the ultimate reason for this being that the partial transpose of a fermionic Gaussian state is no longer Gaussian. To provide a remedy for this state of affairs, in this work, we introduce efficiently computable and rigorous upper and lower bounds to the negativity, making use of techniques of semidefinite programming, building upon the Lagrangian formulation of fermionic linear optics, and exploiting suitable products of Gaussian operators. We discuss examples in quantum many-body theory and hint at applications in the study of topological properties at finite temperature.

  13. Dilation volumes of sets of bounded perimeter

    DEFF Research Database (Denmark)

    Kiderlen, Markus; Rataj, Jan

    , this derivative coincides up to sign with the directional derivative of the covariogram of A in direction u. By known results for the covariogram, this derivative can therefore be expressed by the cosine transform of the surface area measure of A. We extend this result to sets Q that are at most countable and use...... it to determine the derivative of the contact distribution function of a stationary random closed set at zero. A variant for uncountable Q is given, too. The proofs are based on approximation of the characteristic function of A by smooth functions of bounded variation and showing corresponding formulas for them....

  14. Hyperquarks and bosonic preon bound states

    International Nuclear Information System (INIS)

    Schmid, Michael L.; Buchmann, Alfons J.

    2009-01-01

    In a model in which leptons, quarks, and the recently introduced hyperquarks are built up from two fundamental spin-(1/2) preons, the standard model weak gauge bosons emerge as preon bound states. In addition, the model predicts a host of new composite gauge bosons, in particular, those responsible for hyperquark and proton decay. Their presence entails a left-right symmetric extension of the standard model weak interactions and a scheme for a partial and grand unification of nongravitational interactions based on, respectively, the effective gauge groups SU(6) P and SU(9) G . This leads to a prediction of the Weinberg angle at low energies in good agreement with experiment. Furthermore, using evolution equations for the effective coupling strengths, we calculate the partial and grand unification scales, the hyperquark mass scale, as well as the mass and decay rate of the lightest hyperhadron.

  15. Factorization Procedure for Harmonically Bound Brownian Particle

    International Nuclear Information System (INIS)

    Omolo, JK.

    2006-01-01

    The method of factorization to solve the problem of the one-dimensional harmonically bound Brownian particle was applied. Assuming the the rapidily fluctuating random force is Gaussian and has an infinitely short correlation time, explicit expressions for the position-position,velocity-velocity, and the position-velocity correlation functions, which are also use to write down appropriate distribution functions were used. The correlation and distribution functions for the complex quantity (amplititude) which provides the expressions for the position and velocity of the particle are calculated. Finally, Fokker-Planck equations for the joint probability distribution functions for the amplititude and it's complex conjugate as well as for the position and velocity of the particle are obtained. (author)

  16. Lower complexity bounds for lifted inference

    DEFF Research Database (Denmark)

    Jaeger, Manfred

    2015-01-01

    instances of the model. Numerous approaches for such “lifted inference” techniques have been proposed. While it has been demonstrated that these techniques will lead to significantly more efficient inference on some specific models, there are only very recent and still quite restricted results that show...... the feasibility of lifted inference on certain syntactically defined classes of models. Lower complexity bounds that imply some limitations for the feasibility of lifted inference on more expressive model classes were established earlier in Jaeger (2000; Jaeger, M. 2000. On the complexity of inference about...... that under the assumption that NETIME≠ETIME, there is no polynomial lifted inference algorithm for knowledge bases of weighted, quantifier-, and function-free formulas. Further strengthening earlier results, this is also shown to hold for approximate inference and for knowledge bases not containing...

  17. Surface-bound states in nanodiamonds

    Science.gov (United States)

    Han, Peng; Antonov, Denis; Wrachtrup, Jörg; Bester, Gabriel

    2017-05-01

    We show via ab initio calculations and an electrostatic model that the notoriously low, but positive, electron affinity of bulk diamond becomes negative for hydrogen passivated nanodiamonds and argue that this peculiar situation (type-II offset with a vacuum level at nearly midgap) and the three further conditions: (i) a surface dipole with positive charge on the outside layer, (ii) a spherical symmetry, and (iii) a dielectric mismatch at the surface, results in the emergence of a peculiar type of surface state localized just outside the nanodiamond. These states are referred to as "surface-bound states" and have consequently a strong environmental sensitivity. These type of states should exist in any nanostructure with negative electron affinity. We further quantify the band offsets of different type of nanostructures as well as the exciton binding energy and contrast the results with results for "conventional" silicon quantum dots.

  18. Volume Stability of Bitumen Bound Building Blocks

    Directory of Open Access Journals (Sweden)

    Thanaya I.N.A.

    2010-01-01

    Full Text Available This paper covers results of laboratory investigations on the volume stability of masonry units incorporating waste materials bound with bitumen (Bitublocks, due to moisture adsorption, thermal exposure and vacuum saturation. The materials used were steel slag, crushed glass, coal fly ash, and 50 pen bitumen. The samples were produced in hot mix method, compacted, then exposed to moist and temperature. It was found that moisture adsorption from the environment caused the Bitublock to expand. The samples with less intense curing regime experienced lower expansion and became stable faster, and vice versa. Under thermal condition (at 70°C, the samples with less intense curing regime underwent higher expansion, and vice versa. They were also highly reversible. Their volume stability was found unique under water exposure. The expansion on first vacuum saturation cycle was irreversible, then largely reversible on the following cycles.

  19. Extreme hydrothermal conditions at an active plate-bounding fault

    Science.gov (United States)

    Sutherland, Rupert; Townend, John; Toy, Virginia; Upton, Phaedra; Coussens, Jamie; Allen, Michael; Baratin, Laura-May; Barth, Nicolas; Becroft, Leeza; Boese, Carolin; Boles, Austin; Boulton, Carolyn; Broderick, Neil G. R.; Janku-Capova, Lucie; Carpenter, Brett M.; Célérier, Bernard; Chamberlain, Calum; Cooper, Alan; Coutts, Ashley; Cox, Simon; Craw, Lisa; Doan, Mai-Linh; Eccles, Jennifer; Faulkner, Dan; Grieve, Jason; Grochowski, Julia; Gulley, Anton; Hartog, Arthur; Howarth, Jamie; Jacobs, Katrina; Jeppson, Tamara; Kato, Naoki; Keys, Steven; Kirilova, Martina; Kometani, Yusuke; Langridge, Rob; Lin, Weiren; Little, Timothy; Lukacs, Adrienn; Mallyon, Deirdre; Mariani, Elisabetta; Massiot, Cécile; Mathewson, Loren; Melosh, Ben; Menzies, Catriona; Moore, Jo; Morales, Luiz; Morgan, Chance; Mori, Hiroshi; Niemeijer, Andre; Nishikawa, Osamu; Prior, David; Sauer, Katrina; Savage, Martha; Schleicher, Anja; Schmitt, Douglas R.; Shigematsu, Norio; Taylor-Offord, Sam; Teagle, Damon; Tobin, Harold; Valdez, Robert; Weaver, Konrad; Wiersberg, Thomas; Williams, Jack; Woodman, Nick; Zimmer, Martin

    2017-06-01

    Temperature and fluid pressure conditions control rock deformation and mineralization on geological faults, and hence the distribution of earthquakes. Typical intraplate continental crust has hydrostatic fluid pressure and a near-surface thermal gradient of 31 ± 15 degrees Celsius per kilometre. At temperatures above 300-450 degrees Celsius, usually found at depths greater than 10-15 kilometres, the intra-crystalline plasticity of quartz and feldspar relieves stress by aseismic creep and earthquakes are infrequent. Hydrothermal conditions control the stability of mineral phases and hence frictional-mechanical processes associated with earthquake rupture cycles, but there are few temperature and fluid pressure data from active plate-bounding faults. Here we report results from a borehole drilled into the upper part of the Alpine Fault, which is late in its cycle of stress accumulation and expected to rupture in a magnitude 8 earthquake in the coming decades. The borehole (depth 893 metres) revealed a pore fluid pressure gradient exceeding 9 ± 1 per cent above hydrostatic levels and an average geothermal gradient of 125 ± 55 degrees Celsius per kilometre within the hanging wall of the fault. These extreme hydrothermal conditions result from rapid fault movement, which transports rock and heat from depth, and topographically driven fluid movement that concentrates heat into valleys. Shear heating may occur within the fault but is not required to explain our observations. Our data and models show that highly anomalous fluid pressure and temperature gradients in the upper part of the seismogenic zone can be created by positive feedbacks between processes of fault slip, rock fracturing and alteration, and landscape development at plate-bounding faults.

  20. Extreme hydrothermal conditions at an active plate-bounding fault.

    Science.gov (United States)

    Sutherland, Rupert; Townend, John; Toy, Virginia; Upton, Phaedra; Coussens, Jamie; Allen, Michael; Baratin, Laura-May; Barth, Nicolas; Becroft, Leeza; Boese, Carolin; Boles, Austin; Boulton, Carolyn; Broderick, Neil G R; Janku-Capova, Lucie; Carpenter, Brett M; Célérier, Bernard; Chamberlain, Calum; Cooper, Alan; Coutts, Ashley; Cox, Simon; Craw, Lisa; Doan, Mai-Linh; Eccles, Jennifer; Faulkner, Dan; Grieve, Jason; Grochowski, Julia; Gulley, Anton; Hartog, Arthur; Howarth, Jamie; Jacobs, Katrina; Jeppson, Tamara; Kato, Naoki; Keys, Steven; Kirilova, Martina; Kometani, Yusuke; Langridge, Rob; Lin, Weiren; Little, Timothy; Lukacs, Adrienn; Mallyon, Deirdre; Mariani, Elisabetta; Massiot, Cécile; Mathewson, Loren; Melosh, Ben; Menzies, Catriona; Moore, Jo; Morales, Luiz; Morgan, Chance; Mori, Hiroshi; Niemeijer, Andre; Nishikawa, Osamu; Prior, David; Sauer, Katrina; Savage, Martha; Schleicher, Anja; Schmitt, Douglas R; Shigematsu, Norio; Taylor-Offord, Sam; Teagle, Damon; Tobin, Harold; Valdez, Robert; Weaver, Konrad; Wiersberg, Thomas; Williams, Jack; Woodman, Nick; Zimmer, Martin

    2017-06-01

    Temperature and fluid pressure conditions control rock deformation and mineralization on geological faults, and hence the distribution of earthquakes. Typical intraplate continental crust has hydrostatic fluid pressure and a near-surface thermal gradient of 31 ± 15 degrees Celsius per kilometre. At temperatures above 300-450 degrees Celsius, usually found at depths greater than 10-15 kilometres, the intra-crystalline plasticity of quartz and feldspar relieves stress by aseismic creep and earthquakes are infrequent. Hydrothermal conditions control the stability of mineral phases and hence frictional-mechanical processes associated with earthquake rupture cycles, but there are few temperature and fluid pressure data from active plate-bounding faults. Here we report results from a borehole drilled into the upper part of the Alpine Fault, which is late in its cycle of stress accumulation and expected to rupture in a magnitude 8 earthquake in the coming decades. The borehole (depth 893 metres) revealed a pore fluid pressure gradient exceeding 9 ± 1 per cent above hydrostatic levels and an average geothermal gradient of 125 ± 55 degrees Celsius per kilometre within the hanging wall of the fault. These extreme hydrothermal conditions result from rapid fault movement, which transports rock and heat from depth, and topographically driven fluid movement that concentrates heat into valleys. Shear heating may occur within the fault but is not required to explain our observations. Our data and models show that highly anomalous fluid pressure and temperature gradients in the upper part of the seismogenic zone can be created by positive feedbacks between processes of fault slip, rock fracturing and alteration, and landscape development at plate-bounding faults.

  1. Resignation syndrome: Catatonia? Culture-bound?

    Directory of Open Access Journals (Sweden)

    Karl eSallin

    2016-01-01

    Full Text Available Resignation syndrome (RS designates a long-standing disorder predominately affecting psychologically traumatised children and adolescents in the midst of a strenuous and lengthy migration process. Typically a depressive onset is followed by gradual withdrawal progressing via stupor into a state that prompts tube feeding and is characterised by failure to respond even to painful stimuli. The patient is seemingly unconscious. Recovery ensues within months to years and is claimed to be dependent on the restoration of hope to the family.Descriptions of disorders resembling RS can be found in the literature and the condition is unlikely novel. Nevertheless, the magnitude and geographical distribution stand out. Several hundred cases have been reported exclusively in Sweden in the past decade prompting the Swedish National Board of Health and Welfare to recognise RS as a separate diagnostic entity. The currently prevailing stress hypothesis fails to account for the regional distribution and contributes little to treatment. Consequently, a re-evaluation of diagnostics and treatment is required. Psychogenic catatonia is proposed to supply the best fit with the clinical presentation. Treatment response, altered brain metabolism or preserved awareness would support this hypothesis.Epidemiological data suggests culture-bound beliefs and expectations to generate and direct symptom expression and we argue that culture-bound psychogenesis can accommodate the endemic distribution.Last, we review recent models of predictive coding indicating how expectation processes are crucially involved in the placebo and nocebo effect, delusions and conversion disorders. Building on this theoretical framework we propose a neurobiological model of RS in which the impact of overwhelming negative expectations are directly causative of the down-regulation of higher order and lower order behavioural systems in particularly vulnerable individuals.

  2. Models for light QCD bound states

    International Nuclear Information System (INIS)

    LaCourse, D.P.

    1992-01-01

    After a brief overview of Regge, tower, and heavy-quark experimental data, this thesis examines two massless wave equations relevant to quark bound states. We establish general conditions on the Lorentz scalar and Lorentz vector potentials which yield arbitrary leading Regge trajectories for the case of circular classical motion. A semi-classical approximation which includes radial motion reproduces remarkably well the exact solutions. Conditions for tower structure are examined, and found to be incompatible with conditions which give a Nambu stringlike Regge slope. The author then proposes a generalization of the usual potential model of quark bound states in which the confining flux tube is a dynamical object carrying both angular momentum and energy. The Q bar Q-string system with spinless quarks is quantized using an implicit operator technique and the resulting relativistic wave equation is solved. For heavy quarks the usual Schroedinger valence-quark model is recovered. The Regge slope with light quarks agree with the classical rotating-string result and is significantly larger and the effects of short-range forces are also considered. A relativistic generalization of the quantized flux tube model predicts the glueball ground state mass to be √3/α' ≅ 1.9 GeV where α' is the normal Regge slope. The groundstate as well as excited levels like considerably above the expectations of previous models and also above various proposed experimental candidates. The glueball Regge slope is only about three-eighths that for valence quark hadrons. A semi-classical calculation of the Regge slope is in good agreement with a numerically exact value

  3. Coherent structures in wall-bounded turbulence

    Science.gov (United States)

    Jiménez, Javier

    2018-05-01

    This article discusses the description of wall-bounded turbulence as a deterministic high-dimensional dynamical system of interacting coherent structures, defined as eddies with enough internal dynamics to behave relatively autonomously from any remaining incoherent part of the flow. The guiding principle is that randomness is not a property, but a methodological choice of what to ignore in the flow, and that a complete understanding of turbulence, including the possibility of control, requires that it be kept to a minimum. After briefly reviewing the underlying low-order statistics of flows at moderate Reynolds numbers, the article examines what two-point statistics imply for the decomposition of the flow into individual eddies. Intense eddies are examined next, including their temporal evolution, and shown to satisfy many of the properties required for coherence. In particular, it is shown that coherent structures larger than the Corrsin scale are a natural consequence of the shear. In wall-bounded turbulence, they can be classified into coherent dispersive waves and transient bursts. The former are found in the viscous layer near the wall and as very-large structures spanning the boundary layer thickness. Although they are shear-driven, these waves have enough internal structure to maintain a uniform advection velocity. Conversely, bursts exist at all scales, are characteristic of the logarithmic layer, and interact almost linearly with the shear. While the waves require a wall to determine their length scale, the bursts are essentially independent from it. The article concludes with a brief review of our present theoretical understanding of turbulent structures, and with a list of open problems and future perspectives.

  4. Structure of the protein core of translation initiation factor 2 in apo, GTP-bound and GDP-bound forms

    International Nuclear Information System (INIS)

    Simonetti, Angelita; Marzi, Stefano; Fabbretti, Attilio; Hazemann, Isabelle; Jenner, Lasse; Urzhumtsev, Alexandre; Gualerzi, Claudio O.; Klaholz, Bruno P.

    2013-01-01

    The crystal structures of the eubacterial translation initiation factor 2 in apo form and with bound GDP and GTP reveal conformational changes upon nucleotide binding and hydrolysis, notably of the catalytically important histidine in the switch II region. Translation initiation factor 2 (IF2) is involved in the early steps of bacterial protein synthesis. It promotes the stabilization of the initiator tRNA on the 30S initiation complex (IC) and triggers GTP hydrolysis upon ribosomal subunit joining. While the structure of an archaeal homologue (a/eIF5B) is known, there are significant sequence and functional differences in eubacterial IF2, while the trimeric eukaryotic IF2 is completely unrelated. Here, the crystal structure of the apo IF2 protein core from Thermus thermophilus has been determined by MAD phasing and the structures of GTP and GDP complexes were also obtained. The IF2–GTP complex was trapped by soaking with GTP in the cryoprotectant. The structures revealed conformational changes of the protein upon nucleotide binding, in particular in the P-loop region, which extend to the functionally relevant switch II region. The latter carries a catalytically important and conserved histidine residue which is observed in different conformations in the GTP and GDP complexes. Overall, this work provides the first crystal structure of a eubacterial IF2 and suggests that activation of GTP hydrolysis may occur by a conformational repositioning of the histidine residue

  5. Structure of the protein core of translation initiation factor 2 in apo, GTP-bound and GDP-bound forms

    Energy Technology Data Exchange (ETDEWEB)

    Simonetti, Angelita [IGBMC (Institute of Genetics and of Molecular and Cellular Biology), Centre National de la Recherche Scientifique (CNRS) UMR 7104/Institut National de la Santé de la Recherche Médicale - INSERM U964/Université de Strasbourg, 1 Rue Laurent Fries, 67404 Illkirch (France); Marzi, Stefano [Architecture et Réactivité de l’ARN, UPR 9002 CNRS, IBMC (Institute of Molecular and Cellular Biology), 15 Rue R. Descartes, 67084 Strasbourg, France, Université de Strasbourg, 67000 Strasbourg (France); Fabbretti, Attilio [University of Camerino, 62032 Camerino (Monaco) (Italy); Hazemann, Isabelle; Jenner, Lasse [IGBMC (Institute of Genetics and of Molecular and Cellular Biology), Centre National de la Recherche Scientifique (CNRS) UMR 7104/Institut National de la Santé de la Recherche Médicale -INSERM U964/Université de Strasbourg, 1 Rue Laurent Fries, 67404 Illkirch (France); Urzhumtsev, Alexandre [IGBMC (Institute of Genetics and of Molecular and Cellular Biology), Centre National de la Recherche Scientifique (CNRS) UMR 7104/Institut National de la Santé de la Recherche Médicale - INSERM U964/Université de Strasbourg, 1 Rue Laurent Fries, 67404 Illkirch (France); Université de Lorraine, 54506 Vandoeuvre-lès-Nancy (France); Gualerzi, Claudio O. [University of Camerino, 62032 Camerino (Monaco) (Italy); Klaholz, Bruno P., E-mail: klaholz@igbmc.fr [IGBMC (Institute of Genetics and of Molecular and Cellular Biology), Centre National de la Recherche Scientifique (CNRS) UMR 7104/Institut National de la Santé de la Recherche Médicale - INSERM U964/Université de Strasbourg, 1 Rue Laurent Fries, 67404 Illkirch (France)

    2013-06-01

    The crystal structures of the eubacterial translation initiation factor 2 in apo form and with bound GDP and GTP reveal conformational changes upon nucleotide binding and hydrolysis, notably of the catalytically important histidine in the switch II region. Translation initiation factor 2 (IF2) is involved in the early steps of bacterial protein synthesis. It promotes the stabilization of the initiator tRNA on the 30S initiation complex (IC) and triggers GTP hydrolysis upon ribosomal subunit joining. While the structure of an archaeal homologue (a/eIF5B) is known, there are significant sequence and functional differences in eubacterial IF2, while the trimeric eukaryotic IF2 is completely unrelated. Here, the crystal structure of the apo IF2 protein core from Thermus thermophilus has been determined by MAD phasing and the structures of GTP and GDP complexes were also obtained. The IF2–GTP complex was trapped by soaking with GTP in the cryoprotectant. The structures revealed conformational changes of the protein upon nucleotide binding, in particular in the P-loop region, which extend to the functionally relevant switch II region. The latter carries a catalytically important and conserved histidine residue which is observed in different conformations in the GTP and GDP complexes. Overall, this work provides the first crystal structure of a eubacterial IF2 and suggests that activation of GTP hydrolysis may occur by a conformational repositioning of the histidine residue.

  6. Stimulation of Tetrabromobisphenol A Binding to Soil Humic Substances by Birnessite and the Chemical Structure of the Bound Residues.

    Science.gov (United States)

    Tong, Fei; Gu, Xueyuan; Gu, Cheng; Xie, Jinyu; Xie, Xianchuan; Jiang, Bingqi; Wang, Yongfeng; Ertunc, Tanya; Schäffer, Andreas; Ji, Rong

    2016-06-21

    Studies have shown the main fate of the flame retardant tetrabromobisphenol A (TBBPA) in soils is the formation of bound residues, and mechanisms on it are less-understood. This study investigated the effect of birnessite (δ-MnO2), a naturally occurring oxidant in soils, on the formation of bound residues. (14)C-labeled TBBPA was used to investigate the pH dependency of TBBPA bound-residue formation to two soil humic acids (HAs), Elliott soil HA and Steinkreuz soil HA, in the presence of δ-MnO2. The binding of TBBPA and its transformation products to both HAs was markedly increased (3- to 17-fold) at all pH values in the presence of δ-MnO2. More bound residues were formed with the more aromatic Elliott soil HA than with Steinkreuz soil HA. Gel-permeation chromatography revealed a uniform distribution of the bound residues within Steinkreuz soil HA and a nonuniform distribution within Elliott soil HA. (13)C NMR spectroscopy of (13)C-TBBPA residues bound to (13)C-depleted HA suggested that in the presence of δ-MnO2, binding occurred via ester and ether and other types of covalent bonds besides HA sequestration. The insights gained in this study contribute to an understanding of the formation of TBBPA bound residues facilitated by δ-MnO2.

  7. The neural basis of bounded rational behavior

    Directory of Open Access Journals (Sweden)

    Coricelli, Giorgio

    2012-03-01

    Full Text Available Bounded rational behaviour is commonly observed in experimental games and in real life situations. Neuroeconomics can help to understand the mental processing underlying bounded rationality and out-of-equilibrium behaviour. Here we report results from recent studies on the neural basis of limited steps of reasoning in a competitive setting —the beauty contest game. We use functional magnetic resonance imaging (fMRI to study the neural correlates of human mental processes in strategic games. We apply a cognitive hierarchy model to classify subject’s choices in the experimental game according to the degree of strategic reasoning so that we can identify the neural substrates of different levels of strategizing. We found a correlation between levels of strategic reasoning and activity in a neural network related to mentalizing, i.e. the ability to think about other’s thoughts and mental states. Moreover, brain data showed how complex cognitive processes subserve the higher level of reasoning about others. We describe how a cognitive hierarchy model fits both behavioural and brain data.

    La racionalidad limitada es un fenómeno observado de manera frecuente tanto en juegos experimentales como en situaciones cotidianas. La Neuroeconomía puede mejorar la comprensión de los procesos mentales que caracterizan la racionalidad limitada; en paralelo nos puede ayudar a comprender comportamientos que violan el equilibrio. Nuestro trabajo presenta resultados recientes sobre la bases neuronales del razonamiento estratégico (y sus límite en juegos competitivos —como el juego del “beauty contest”. Estudiamos las bases neuronales del comportamiento estratégico en juegos con interacción entre sujetos usando resonancia magnética funcional (fMRI. Las decisiones de los participantes se clasifican acorde al grado de razonamiento estratégico: el llamado modelo de Jerarquías Cognitivas. Los resultados muestran una correlación entre niveles de

  8. Tight bounds on computing error-correcting codes by bounded-depth circuits with arbitrary gates

    DEFF Research Database (Denmark)

    Gal, A.; Hansen, Kristoffer Arnsfelt; Koucky, Michal

    2013-01-01

    We bound the minimum number w of wires needed to compute any (asymptotically good) error-correcting code C:{0,1}Ω(n)→{0,1}n with minimum distance Ω(n), using unbounded fan-in circuits of depth d with arbitrary gates. Our main results are: 1) if d=2, then w=Θ(n (lgn/lglgn)2); 2) if d=3, then w...

  9. Tight bounds on computing error-correcting codes by bounded-depth circuits with arbitrary gates

    DEFF Research Database (Denmark)

    Gál, Anna; Hansen, Kristoffer Arnsfelt; Koucký, Michal

    2012-01-01

    We bound the minimum number w of wires needed to compute any (asymptotically good) error-correcting code C:{0,1}Ω(n) -> {0,1}n with minimum distance Ω(n), using unbounded fan-in circuits of depth d with arbitrary gates. Our main results are: (1) If d=2 then w = Θ(n ({log n/ log log n})2). (2) If d...

  10. Peptide carrier-mediated non-covalent delivery of unmodified cisplatin, methotrexate and other agents via intravenous route to the brain.

    Directory of Open Access Journals (Sweden)

    Gobinda Sarkar

    Full Text Available BACKGROUND: Rapid pre-clinical evaluation of chemotherapeutic agents against brain cancers and other neurological disorders remains largely unattained due to the presence of the blood-brain barrier (BBB, which limits transport of most therapeutic compounds to the brain. A synthetic peptide carrier, K16ApoE, was previously developed that enabled transport of target proteins to the brain by mimicking a ligand-receptor system. The peptide carrier was found to generate transient BBB permeability, which was utilized for non-covalent delivery of cisplatin, methotrexate and other compounds to the brain. APPROACH: Brain delivery of the chemotherapeutics and other agents was achieved either by injecting the carrier peptide and the drugs separately or as a mixture, to the femoral vein. A modification of the method comprised injection of K16ApoE pre-mixed with cetuximab, followed by injection of a 'small-molecule' drug. PRINCIPAL FINDINGS: Seven-of-seven different small molecules were successfully delivered to the brain via K16ApoE. Depending on the method, brain uptake with K16ApoE was 0.72-1.1% for cisplatin and 0.58-0.92% for methotrexate (34-50-fold and 54-92 fold greater for cisplatin and methotrexate, respectively, with K16ApoE than without. Visually intense brain-uptake of Evans Blue, Light Green SF and Crocein scarlet was also achieved. Direct intracranial injection of EB show locally restricted distribution of the dye in the brain, whereas K16ApoE-mediated intravenous injection of EB resulted in the distribution of the dye throughout the brain. Experiments with insulin suggest that ligand-receptor signaling intrinsic to the BBB provides a natural means for passive transport of some molecules across the BBB. SIGNIFICANCE: The results suggest that the carrier peptide can non-covalently transport various chemotherapeutic agents to the brain. Thus, the method offers an avenue for pre-clinical evaluation of various small and large therapeutic molecules

  11. Noncovalent functionalization of pristine CVD single-walled carbon nanotubes with 3d metal(II) phthalocyanines by adsorption from the gas phase

    Science.gov (United States)

    Basiuk, Vladimir A.; Flores-Sánchez, Laura J.; Meza-Laguna, Victor; Flores-Flores, José Ocotlán; Bucio-Galindo, Lauro; Puente-Lee, Iván; Basiuk, Elena V.

    2018-04-01

    Noncovalent hybrids of carbon nanotubes (CNTs) with phthalocyanines (Pcs) is a subject of growing research effort focused on the development of new efficient organic photovoltaic cells, heterogeneous catalysts, lithium batteries, gas sensors, field effect transistors, among other possible applications. The main advantage of using unsubstituted Pcs is their very moderate cost and easy commercial availability. Unfortunately, the deposition of unsubstituted Pcs onto CNT sidewalls via the traditional liquid-phase strategy proves to be very problematic due to an extremely poor solubility of Pcs. At the same time, unsubstituted free-base H2Pc ligand and many of its transition metal complexes exhibit high thermal stability and volatility under reduced pressure, which allows for their physical vapor deposition onto solid surfaces. In the present work, we demonstrated the possibility of simple, fast, efficient and environmentally friendly noncovalent functionalization of single-walled CNTs (SWNTs) with a series of 3d metal(II) phthalocyanines Me(II)Pc, where Me = Co, Ni, Cu and Zn. The functionalization can be performed at 400-500 °C under moderate vacuum, and takes about 2-3 h only. The nanohybrids obtained were characterized by means of Fourier-transform infrared, Raman, UV-vis and energy-dispersive X-ray spectroscopy (EDS), thermogravimetric analysis (TGA), scanning and transmission electron microscopy. TGA suggested that Pc weight content is 30%, 17% and 35% for NiPc, CuPc and ZnPc, respectively (CoPc exhibited anomalous behavior), which is close to the estimates from EDS spectra of 24-39%, 27-36% and 27-44% for CoPc, CuPc and ZnPc, respectively. A strong increase in intensity of D band in the Raman spectra of SWNT‒Pc hybrids, as compared to that of pristine nanotubes, was interpreted as very strong interactions between Pc molecules and SWNT sidewalls. Very high absolute values of binding energies of 32.46-37.12 kcal/mol and the patterns of HOMO and LUMO distribution

  12. A look at the density functional theory zoo with the advanced GMTKN55 database for general main group thermochemistry, kinetics and noncovalent interactions.

    Science.gov (United States)

    Goerigk, Lars; Hansen, Andreas; Bauer, Christoph; Ehrlich, Stephan; Najibi, Asim; Grimme, Stefan

    2017-12-13

    We present the GMTKN55 benchmark database for general main group thermochemistry, kinetics and noncovalent interactions. Compared to its popular predecessor GMTKN30 [Goerigk and Grimme J. Chem. Theory Comput., 2011, 7, 291], it allows assessment across a larger variety of chemical problems-with 13 new benchmark sets being presented for the first time-and it also provides reference values of significantly higher quality for most sets. GMTKN55 comprises 1505 relative energies based on 2462 single-point calculations and it is accessible to the user community via a dedicated website. Herein, we demonstrate the importance of better reference values, and we re-emphasise the need for London-dispersion corrections in density functional theory (DFT) treatments of thermochemical problems, including Minnesota methods. We assessed 217 variations of dispersion-corrected and -uncorrected density functional approximations, and carried out a detailed analysis of 83 of them to identify robust and reliable approaches. Double-hybrid functionals are the most reliable approaches for thermochemistry and noncovalent interactions, and they should be used whenever technically feasible. These are, in particular, DSD-BLYP-D3(BJ), DSD-PBEP86-D3(BJ), and B2GPPLYP-D3(BJ). The best hybrids are ωB97X-V, M052X-D3(0), and ωB97X-D3, but we also recommend PW6B95-D3(BJ) as the best conventional global hybrid. At the meta-generalised-gradient (meta-GGA) level, the SCAN-D3(BJ) method can be recommended. Other meta-GGAs are outperformed by the GGA functionals revPBE-D3(BJ), B97-D3(BJ), and OLYP-D3(BJ). We note that many popular methods, such as B3LYP, are not part of our recommendations. In fact, with our results we hope to inspire a change in the user community's perception of common DFT methods. We also encourage method developers to use GMTKN55 for cross-validation studies of new methodologies.

  13. Persistence-Based Branch Misprediction Bounds for WCET Analysis

    DEFF Research Database (Denmark)

    Puffitsch, Wolfgang

    2015-01-01

    Branch prediction is an important feature of pipelined processors to achieve high performance. However, it can lead to overly pessimistic worst-case execution time (WCET) bounds when being modeled too conservatively. This paper presents bounds on the number of branch mispredictions for local...... dynamic branch predictors. To handle interferences between branch instructions we use the notion of persistence, a concept that is also found in cache analyses. The bounds apply to branches in general, not only to branches that close a loop. Furthermore, the bounds can be easily integrated into integer...... linear programming formulations of the WCET problem. An evaluation on a number of benchmarks shows that with these bounds, dynamic branch prediction does not necessarily lead to higher WCET bounds than static prediction schemes....

  14. Architecture-independent power bound for vibration energy harvesters

    International Nuclear Information System (INIS)

    Halvorsen, E; Le, C P; Mitcheson, P D; Yeatman, E M

    2013-01-01

    The maximum output power of energy harvesters driven by harmonic vibrations is well known for a range of specific harvester architectures. An architecture-independent bound based on the mechanical input-power also exists and gives a strict limit on achievable power with one mechanical degree of freedom, but is a least upper bound only for lossless devices. We report a new theoretical bound on the output power of vibration energy harvesters that includes parasitic, linear mechanical damping while still being architecture independent. This bound greatly improves the previous bound at moderate force amplitudes and is compared to the performance of established harvester architectures which are shown to agree with it in limiting cases. The bound is a hard limit on achievable power with one mechanical degree of freedom and can not be circumvented by transducer or power-electronic-interface design

  15. Sharp bounds for periodic solutions of Lipschitzian differential equations

    International Nuclear Information System (INIS)

    Zevin, A A

    2009-01-01

    A general system of Lipschitzian differential equations, containing simultaneously terms without delay and with arbitrary constant and time-varying delays, is considered. For the autonomous case, a lower bound for the period of nonconstant periodic solutions, expressed in the respective supremum Lipschitz constants, is found. For nonautonomous periodic equations, explicit upper bounds for the amplitudes and maximum derivatives of periodic solutions are obtained. For all n ≥ 2, the bounds do not depend on n and, in general, are different from that for n = 1. All the bounds are sharp; they are attained in linear differential equations with piece-wise constant deviating arguments. A relation between the obtained bounds and the sharp bounds in other metrics is established

  16. ``Carbon Credits'' for Resource-Bounded Computations Using Amortised Analysis

    Science.gov (United States)

    Jost, Steffen; Loidl, Hans-Wolfgang; Hammond, Kevin; Scaife, Norman; Hofmann, Martin

    Bounding resource usage is important for a number of areas, notably real-time embedded systems and safety-critical systems. In this paper, we present a fully automatic static type-based analysis for inferring upper bounds on resource usage for programs involving general algebraic datatypes and full recursion. Our method can easily be used to bound any countable resource, without needing to revisit proofs. We apply the analysis to the important metrics of worst-case execution time, stack- and heap-space usage. Our results from several realistic embedded control applications demonstrate good matches between our inferred bounds and measured worst-case costs for heap and stack usage. For time usage we infer good bounds for one application. Where we obtain less tight bounds, this is due to the use of software floating-point libraries.

  17. A simple but usually fast branch-and-bound algorithm for the capacitated facility location problem

    DEFF Research Database (Denmark)

    Görtz, Simon; Klose, Andreas

    2012-01-01

    This paper presents a simple branch-and-bound method based on Lagrangean relaxation and subgradient optimization for solving large instances of the capacitated facility location problem (CFLP) to optimality. To guess a primal solution to the Lagrangean dual, we average solutions to the Lagrangean...... subproblem. Branching decisions are then based on this estimated (fractional) primal solution. Extensive numerical results reveal that the method is much faster and more robust than other state-of-the-art methods for solving the CFLP exactly....

  18. Interaction of solitons and the formation of bound states in the generalized Lugiato-Lefever equation

    Science.gov (United States)

    Parra-Rivas, Pedro; Gomila, Damia; Colet, Pere; Gelens, Lendert

    2017-07-01

    Bound states, also called soliton molecules, can form as a result of the interaction between individual solitons. This interaction is mediated through the tails of each soliton that overlap with one another. When such soliton tails have spatial oscillations, locking or pinning between two solitons can occur at fixed distances related with the wavelength of these oscillations, thus forming a bound state. In this work, we study the formation and stability of various types of bound states in the Lugiato-Lefever equation by computing their interaction potential and by analyzing the properties of the oscillatory tails. Moreover, we study the effect of higher order dispersion and noise in the pump intensity on the dynamics of bound states. In doing so, we reveal that perturbations to the Lugiato-Lefever equation that maintain reversibility, such as fourth order dispersion, lead to bound states that tend to separate from one another in time when noise is added. This separation force is determined by the shape of the envelope of the interaction potential, as well as an additional Brownian ratchet effect. In systems with broken reversibility, such as third order dispersion, this ratchet effect continues to push solitons within a bound state apart. However, the force generated by the envelope of the potential is now such that it pushes the solitons towards each other, leading to a null net drift of the solitons. Contribution to the Topical Issue "Theory and Applications of the Lugiato-Lefever Equation", edited by Yanne K. Chembo, Damia Gomila, Mustapha Tlidi, Curtis R. Menyuk.

  19. Electrospray soft-landing for the construction of non-covalent molecular nanostructures using charged droplets under ambient conditions.

    Science.gov (United States)

    Hou, Jian; Zheng, Qingna; Badu-Tawiah, Abraham K; Xiong, Caiqiao; Guan, Cuizhong; Chen, Suming; Nie, Zongxiu; Wang, Dong; Wan, Lijun

    2016-11-17

    An electrospray soft-landing (SL) technique was utilized to create 2D nano-networks on HOPG under ambient conditions. A 2,3,6,7,10,11-hexahydroxy-triphenylene close-packing structure was observed by STM instead of unorganized clusters, as well as amine and acid nanostructures. On C 18 H 37 NH 2 networks, C 18 H 37 NH 3 + was identified by XPS analysis revealing retaining of charges on the SL-modified surface.

  20. Lying for the Greater Good: Bounded Rationality in a Team

    OpenAIRE

    Oktay Sürücü

    2014-01-01

    This paper is concerned with the interaction between fully and boundedly rational agents in situations where their interests are perfectly aligned. The cognitive limitations of the boundedly rational agent do not allow him to fully understand the market conditions and lead him to take non-optimal decisions in some situations. Using categorization to model bounded rationality, we show that the fully rational agent can nudge, i.e., he can manipulate the information he sends and decrease the exp...

  1. Upper bounds on minimum cardinality of exact and approximate reducts

    KAUST Repository

    Chikalov, Igor

    2010-01-01

    In the paper, we consider the notions of exact and approximate decision reducts for binary decision tables. We present upper bounds on minimum cardinality of exact and approximate reducts depending on the number of rows (objects) in the decision table. We show that the bound for exact reducts is unimprovable in the general case, and the bound for approximate reducts is almost unimprovable in the general case. © 2010 Springer-Verlag Berlin Heidelberg.

  2. Entropic Lower Bound for Distinguishability of Quantum States

    Directory of Open Access Journals (Sweden)

    Seungho Yang

    2015-01-01

    Full Text Available For a system randomly prepared in a number of quantum states, we present a lower bound for the distinguishability of the quantum states, that is, the success probability of determining the states in the form of entropy. When the states are all pure, acquiring the entropic lower bound requires only the density operator and the number of the possible states. This entropic bound shows a relation between the von Neumann entropy and the distinguishability.

  3. Uniform Bounds for Black--Scholes Implied Volatility

    OpenAIRE

    Tehranchi, Michael Rummine

    2016-01-01

    In this note, Black--Scholes implied volatility is expressed in terms of various optimization problems. From these representations, upper and lower bounds are derived which hold uniformly across moneyness and call price. Various symmetries of the Black--Scholes formula are exploited to derive new bounds from old. These bounds are used to reprove asymptotic formulas for implied volatility at extreme strikes and/or maturities. the Society for Industrial and Applied Mathematics 10.1137/14095248X

  4. Uniform bounds for Black--Scholes implied volatility

    OpenAIRE

    Tehranchi, Michael R.

    2015-01-01

    In this note, Black--Scholes implied volatility is expressed in terms of various optimisation problems. From these representations, upper and lower bounds are derived which hold uniformly across moneyness and call price. Various symmetries of the Black--Scholes formula are exploited to derive new bounds from old. These bounds are used to reprove asymptotic formulae for implied volatility at extreme strikes and/or maturities.

  5. On an extension of the space of bounded deformations

    Czech Academy of Sciences Publication Activity Database

    Kružík, Martin; Zimmer, J.

    2012-01-01

    Roč. 31, č. 1 (2012), s. 75-91 ISSN 0232-2064 R&D Projects: GA AV ČR IAA100750802 Institutional research plan: CEZ:AV0Z10750506 Keywords : Bounded sequences of symmetrised gradients * bounded deformation Subject RIV: BA - General Mathematics Impact factor: 0.620, year: 2012 http://library.utia.cas.cz/separaty/2012/MTR/kruzik-on an extension of the space of bounded deformations.pdf

  6. General bounds in Hybrid Natural Inflation

    Science.gov (United States)

    Germán, Gabriel; Herrera-Aguilar, Alfredo; Hidalgo, Juan Carlos; Sussman, Roberto A.; Tapia, José

    2017-12-01

    Recently we have studied in great detail a model of Hybrid Natural Inflation (HNI) by constructing two simple effective field theories. These two versions of the model allow inflationary energy scales as small as the electroweak scale in one of them or as large as the Grand Unification scale in the other, therefore covering the whole range of possible energy scales. In any case the inflationary sector of the model is of the form V(phi)=V0 (1+a cos(phi/f)) where 0waterfall field. One interesting characteristic of this model is that the slow-roll parameter epsilon(phi) is a non-monotonic function of phi presenting a maximum close to the inflection point of the potential. Because the scalar spectrum Script Ps(k) of density fluctuations when written in terms of the potential is inversely proportional to epsilon(phi) we find that Script Ps(k) presents a minimum at phimin. The origin of the HNI potential can be traced to a symmetry breaking phenomenon occurring at some energy scale f which gives rise to a (massless) Goldstone boson. Non-perturbative physics at some temperature Tmodels is not common. We use this property of HNI to determine bounds for the inflationary energy scale Δ and for the tensor-to-scalar ratio r.

  7. Probabilistic error bounds for reduced order modeling

    Energy Technology Data Exchange (ETDEWEB)

    Abdo, M.G.; Wang, C.; Abdel-Khalik, H.S., E-mail: abdo@purdue.edu, E-mail: wang1730@purdue.edu, E-mail: abdelkhalik@purdue.edu [Purdue Univ., School of Nuclear Engineering, West Lafayette, IN (United States)

    2015-07-01

    Reduced order modeling has proven to be an effective tool when repeated execution of reactor analysis codes is required. ROM operates on the assumption that the intrinsic dimensionality of the associated reactor physics models is sufficiently small when compared to the nominal dimensionality of the input and output data streams. By employing a truncation technique with roots in linear algebra matrix decomposition theory, ROM effectively discards all components of the input and output data that have negligible impact on reactor attributes of interest. This manuscript introduces a mathematical approach to quantify the errors resulting from the discarded ROM components. As supported by numerical experiments, the introduced analysis proves that the contribution of the discarded components could be upper-bounded with an overwhelmingly high probability. The reverse of this statement implies that the ROM algorithm can self-adapt to determine the level of the reduction needed such that the maximum resulting reduction error is below a given tolerance limit that is set by the user. (author)

  8. Tensor squeezed limits and the Higuchi bound

    Energy Technology Data Exchange (ETDEWEB)

    Bordin, Lorenzo [SISSA, via Bonomea 265, 34136, Trieste (Italy); Creminelli, Paolo [Abdus Salam International Centre for Theoretical Physics, Strada Costiera 11, 34151, Trieste (Italy); Mirbabayi, Mehrdad [Institute for Advanced Study, Princeton, NJ 08540 (United States); Noreña, Jorge, E-mail: lbordin@sissa.it, E-mail: creminel@ictp.it, E-mail: mehrdadm@ias.edu, E-mail: jorge.norena@pucv.cl [Instituto de Física, Pontificia Universidad Católica de Valparaíso, Avenida Universidad 330, Curauma, Valparaíso (Chile)

    2016-09-01

    We point out that tensor consistency relations—i.e. the behavior of primordial correlation functions in the limit a tensor mode has a small momentum—are more universal than scalar consistency relations. They hold in the presence of multiple scalar fields and as long as anisotropies are diluted exponentially fast. When de Sitter isometries are approximately respected during inflation this is guaranteed by the Higuchi bound, which forbids the existence of light particles with spin: de Sitter space can support scalar hair but no curly hair. We discuss two indirect ways to look for the violation of tensor consistency relations in observations, as a signature of models in which inflation is not a strong isotropic attractor, such as solid inflation: (a) graviton exchange contribution to the scalar four-point function; (b) quadrupolar anisotropy of the scalar power spectrum due to super-horizon tensor modes. This anisotropy has a well-defined statistics which can be distinguished from cases in which the background has a privileged direction.

  9. Decision theory with resource-bounded agents.

    Science.gov (United States)

    Halpern, Joseph Y; Pass, Rafael; Seeman, Lior

    2014-04-01

    There have been two major lines of research aimed at capturing resource-bounded players in game theory. The first, initiated by Rubinstein (), charges an agent for doing costly computation; the second, initiated by Neyman (), does not charge for computation, but limits the computation that agents can do, typically by modeling agents as finite automata. We review recent work on applying both approaches in the context of decision theory. For the first approach, we take the objects of choice in a decision problem to be Turing machines, and charge players for the "complexity" of the Turing machine chosen (e.g., its running time). This approach can be used to explain well-known phenomena like first-impression-matters biases (i.e., people tend to put more weight on evidence they hear early on) and belief polarization (two people with different prior beliefs, hearing the same evidence, can end up with diametrically opposed conclusions) as the outcomes of quite rational decisions. For the second approach, we model people as finite automata, and provide a simple algorithm that, on a problem that captures a number of settings of interest, provably performs optimally as the number of states in the automaton increases. Copyright © 2014 Cognitive Science Society, Inc.

  10. Boudot's Range-Bounded Commitment Scheme Revisited

    Science.gov (United States)

    Cao, Zhengjun; Liu, Lihua

    Checking whether a committed integer lies in a specific interval has many cryptographic applications. In Eurocrypt'98, Chan et al. proposed an instantiation (CFT Proof). Based on CFT, Boudot presented a popular range-bounded commitment scheme in Eurocrypt'2000. Both CFT Proof and Boudot Proof are based on the encryption E(x, r)=g^xh^r mod n, where n is an RSA modulus whose factorization is unknown by the prover. They did not use a single base as usual. Thus an increase in cost occurs. In this paper, we show that it suffices to adopt a single base. The cost of the modified Boudot Proof is about half of that of the original scheme. Moreover, the key restriction in the original scheme, i.e., both the discrete logarithm of g in base h and the discrete logarithm of h in base g are unknown by the prover, which is a potential menace to the Boudot Proof, is definitely removed.

  11. Dynamics of water bound to crystalline cellulose

    Energy Technology Data Exchange (ETDEWEB)

    O’Neill, Hugh; Pingali, Sai Venkatesh; Petridis, Loukas; He, Junhong; Mamontov, Eugene; Hong, Liang; Urban, Volker; Evans, Barbara; Langan, Paul; Smith, Jeremy C.; Davison, Brian H.

    2017-09-19

    Interactions of water with cellulose are of both fundamental and technological importance. Here, we characterize the properties of water associated with cellulose using deuterium labeling, neutron scattering and molecular dynamics simulation. Quasi-elastic neutron scattering provided quantitative details about the dynamical relaxation processes that occur and was supported by structural characterization using small-angle neutron scattering and X-ray diffraction. We can unambiguously detect two populations of water associated with cellulose. The first is “non-freezing bound” water that gradually becomes mobile with increasing temperature and can be related to surface water. The second population is consistent with confined water that abruptly becomes mobile at ~260 K, and can be attributed to water that accumulates in the narrow spaces between the microfibrils. Quantitative analysis of the QENS data showed that, at 250 K, the water diffusion coefficient was 0.85 ± 0.04 × 10-10 m2sec-1 and increased to 1.77 ± 0.09 × 10-10 m2sec-1 at 265 K. MD simulations are in excellent agreement with the experiments and support the interpretation that water associated with cellulose exists in two dynamical populations. Our results provide clarity to previous work investigating the states of bound water and provide a new approach for probing water interactions with lignocellulose materials.

  12. Bounding the Higgs boson width through interferometry.

    Science.gov (United States)

    Dixon, Lance J; Li, Ye

    2013-09-13

    We study the change in the diphoton-invariant-mass distribution for Higgs boson decays to two photons, due to interference between the Higgs resonance in gluon fusion and the continuum background amplitude for gg→γγ. Previously, the apparent Higgs mass was found to shift by around 100 MeV in the standard model in the leading-order approximation, which may potentially be experimentally observable. We compute the next-to-leading-order QCD corrections to the apparent mass shift, which reduce it by about 40%. The apparent mass shift may provide a way to measure, or at least bound, the Higgs boson width at the Large Hadron Collider through "interferometry." We investigate how the shift depends on the Higgs width, in a model that maintains constant Higgs boson signal yields. At Higgs widths above 30 MeV, the mass shift is over 200 MeV and increases with the square root of the width. The apparent mass shift could be measured by comparing with the ZZ* channel, where the shift is much smaller. It might be possible to measure the shift more accurately by exploiting its strong dependence on the Higgs transverse momentum.

  13. Phenomenology of wall-bounded Newtonian turbulence.

    Science.gov (United States)

    L'vov, Victor S; Pomyalov, Anna; Procaccia, Itamar; Zilitinkevich, Sergej S

    2006-01-01

    We construct a simple analytic model for wall-bounded turbulence, containing only four adjustable parameters. Two of these parameters are responsible for the viscous dissipation of the components of the Reynolds stress tensor. The other two parameters control the nonlinear relaxation of these objects. The model offers an analytic description of the profiles of the mean velocity and the correlation functions of velocity fluctuations in the entire boundary region, from the viscous sublayer, through the buffer layer, and further into the log-law turbulent region. In particular, the model predicts a very simple distribution of the turbulent kinetic energy in the log-law region between the velocity components: the streamwise component contains a half of the total energy whereas the wall-normal and cross-stream components contain a quarter each. In addition, the model predicts a very simple relation between the von Kármán slope k and the turbulent velocity in the log-law region v+ (in wall units): v+=6k. These predictions are in excellent agreement with direct numerical simulation data and with recent laboratory experiments.

  14. Organically bound tritium analysis in environmental samples

    Energy Technology Data Exchange (ETDEWEB)

    Baglan, N. [CEA/DAM/DIF, Arpajon (France); Kim, S.B. [AECL, Chalk River Laboratories, Chalk River, ON (Canada); Cossonnet, C. [IRSN/PRP-ENV/STEME/LMRE, Orsay (France); Croudace, I.W.; Warwick, P.E. [GAU-Radioanalytical, University of Southampton, Southampton (United Kingdom); Fournier, M. [IRSN/DG/DMQ, Fontenay-aux-Roses (France); Galeriu, D. [IFIN-HH, Horia-Hulubei, Inst. Phys. and Nucl. Eng., Bucharest (Romania); Momoshima, N. [Kyushu University, Radioisotope Ctr., Fukuoka (Japan); Ansoborlo, E. [CEA/DEN/DRCP/CETAMA, Bagnols-sur-Ceze (France)

    2015-03-15

    Organically bound tritium (OBT) has become of increased interest within the last decade, with a focus on its behaviour and also its analysis, which are important to assess tritium distribution in the environment. In contrast, there are no certified reference materials and no standard analytical method through the international organization related to OBT. In order to resolve this issue, an OBT international working group was created in May 2012. Over 20 labs from around the world participated and submitted their results for the first intercomparison exercise results on potato (Sep 2013). The samples, specially-prepared potatoes, were provided in March 2013 to each participant. Technical information and results from this first exercise are discussed here for all the labs which have realised the five replicates necessary to allow a reliable statistical treatment. The results are encouraging as the increased number of participating labs did not degrade the observed dispersion of the results for a similar activity level. Therefore, the results do not seem to depend on the analytical procedure used. From this work an optimised procedure can start to be developed to deal with OBT analysis and will guide subsequent planned OBT trials by the international group.

  15. Revisiting cosmological bounds on sterile neutrinos

    Energy Technology Data Exchange (ETDEWEB)

    Vincent, Aaron C. [Institute for Particle Physics Phenomenology (IPPP), Department of Physics, Durham University, Durham DH1 3LE (United Kingdom); Martínez, Enrique Fernández [Departamento and Instituto de Física Teórica (IFT), UAM/CSIC, Universidad Autonoma de Madrid, C/ Nicolás Cabrera 13-15, E-28049 Cantoblanco, Madrid (Spain); Hernández, Pilar; Mena, Olga [Instituto de Física Corpuscular (IFIC), CSIC-Universitat de València, Apartado de Correos 22085, E-46071 Valencia (Spain); Lattanzi, Massimiliano, E-mail: aaron.vincent@durham.ac.uk, E-mail: enrique.fernandez-martinez@uam.es, E-mail: m.pilar.hernandez@uv.es, E-mail: omena@ific.uv.es, E-mail: lattanzi@fe.infn.it [Dipartimento di Fisica e Science della Terra, Università di Ferrara and INFN, sezione di Ferrara, Polo Scientifico e Tecnologico, Edificio C Via Saragat, 1, I-44122 Ferrara (Italy)

    2015-04-01

    We employ state-of-the art cosmological observables including supernova surveys and BAO information to provide constraints on the mass and mixing angle of a non-resonantly produced sterile neutrino species, showing that cosmology can effectively rule out sterile neutrinos which decay between BBN and the present day. The decoupling of an additional heavy neutrino species can modify the time dependence of the Universe's expansion between BBN and recombination and, in extreme cases, lead to an additional matter-dominated period; while this could naively lead to a younger Universe with a larger Hubble parameter, it could later be compensated by the extra radiation expected in the form of neutrinos from sterile decay. However, recombination-era observables including the Cosmic Microwave Background (CMB), the shift parameter R{sub CMB} and the sound horizon r{sub s} from Baryon Acoustic Oscillations (BAO) severely constrain this scenario. We self-consistently include the full time-evolution of the coupled sterile neutrino and standard model sectors in an MCMC, showing that if decay occurs after BBN, the sterile neutrino is essentially bounded by the constraint sin{sup 2}θ ∼< 0.026 (m{sub s}/eV){sup −2}.

  16. Nonlinear delay monopoly with bounded rationality

    International Nuclear Information System (INIS)

    Matsumoto, Akio; Szidarovszky, Ferenc

    2012-01-01

    The purpose of this paper is to study the dynamics of a monopolistic firm in a continuous-time framework. The firm is assumed to be boundedly rational and to experience time delays in obtaining and implementing information on output. The dynamic adjustment process is based on the gradient of the expected profit. The paper is divided into three parts: we examine delay effects on dynamics caused by one-time delay and two-time delays in the first two parts. Global dynamics and analytical results on local dynamics are numerically confirmed in the third part. Four main results are demonstrated. First, the stability switch from stability to instability occurs only once in the case of a single delay. Second, the alternation of stability and instability can continue if two time delays are involved. Third, the occurence of Hopf bifurcation is analytically shown if stability is lost. Finally, in a bifurcation process, there are a period-doubling cascade to chaos and a period-halving cascade to the equilibrium point in the case of two time delays if the difference between the two delays is large.

  17. NITRO MUSK BOUND TO CARP HEMOGLOBIN ...

    Science.gov (United States)

    Nitroaromatic compounds including synthetic nitro musks are important raw materials and intermediates in the synthesis of explosives, dyes, and pesticides, pharmaceutical and personal care-products (PPCPs). The nitro musks such as musk xylene (MX) and musk ketone (MK) are extensively used as fragrance ingredients in PPCPs and other commercial toiletries. Identification and quantification of a bound 4-amino-MX (4-AMX) metabolite as well as a 2- amino-MK (2-AMK) metabolite were carried out by gas chromatography-mass spectrometry' (GC/MS), with selected ion monitoring (SIM) in both the electron ionization (ElMS) and electron capture (EC) negative ion chemical ionization (NICIMS) modes. Detection of 4-AMX and 2-AMK occurred after the cysteine adducts in carp hemoglobin, derived from the nitroso metabolites, were released by alkaline hydrolysis. The released metabolites were extracted into n-hexane. The extract was preconcentrated by evaporation, and analyzed by GC-SIM-MS. A comparison between the El and EC approaches was made. EC NICIMS detected both metabolites whereas only 4-AMX was detected by ElMS. The EC NICIMS approach exhibited fewer matrix responses and provided a lower detection limit. Quantitation in both approaches was based on internal standard and a calibration plot. The research focused on in the subtasks is the development and application of state-of the-art technologies to meet the needs of the public, Office of Water, and ORD in the area of Water Q

  18. Charged boson bound states in the kerr-newman metric

    International Nuclear Information System (INIS)

    Li Yuanjie; Zhang Duanming

    1986-01-01

    Charged boson bound states in Kerr-Newman metric are discussed. It is found that massless boson cannot be attracted by Kerr-Newman black hole to form bound states. For the massive boson, the condition of the nonbound states when 0 2 - Q 2 and both the condition and wave functions of the bound states when a = √M 2 - Q 2 are obtained. The energy mode of the bound states is single, E = (m√M 2 - Q 2 + eQM)/(2M 2 - Q 2 ). When Q = 0 or e = 0, the conclusion is in agreement with that of Zhang Shiwei and Su Rukeng

  19. On the Applicability of Lower Bounds for Solving Rectilinear

    DEFF Research Database (Denmark)

    Clausen, Jens; Karisch, Stefan E.; Perregaard, M.

    1998-01-01

    . Recently, lower bounds based on decomposition were proposed for the so called rectilinear QAP that proved to be the strongest for a large class of problem instances. We investigate the strength of these bounds when applied not only at the root node of a search tree but as the bound function used......The quadratic assignment problem (QAP) belongs to the hard core of NP-hard optimization problems. After almost forty years of research only relatively small instances can be solved to optimality. The reason is that the quality of the lower bounds available for exact methods is not sufficient...

  20. Upper bounds on quantum uncertainty products and complexity measures

    Energy Technology Data Exchange (ETDEWEB)

    Guerrero, Angel; Sanchez-Moreno, Pablo; Dehesa, Jesus S. [Department of Atomic, Molecular and Nuclear Physics, University of Granada, Granada (Spain); Department of Applied Mathematics, University of Granada, Granada (Spain) and Institute Carlos I for Computational and Theoretical Physics, University of Granada, Granada (Spain); Department of Atomic, Molecular and Nuclear Physics, University of Granada, Granada (Spain); Institute Carlos I for Computational and Theoretical Physics, University of Granada, Granada (Spain)

    2011-10-15

    The position-momentum Shannon and Renyi uncertainty products of general quantum systems are shown to be bounded not only from below (through the known uncertainty relations), but also from above in terms of the Heisenberg-Kennard product . Moreover, the Cramer-Rao, Fisher-Shannon, and Lopez-Ruiz, Mancini, and Calbet shape measures of complexity (whose lower bounds have been recently found) are also bounded from above. The improvement of these bounds for systems subject to spherically symmetric potentials is also explicitly given. Finally, applications to hydrogenic and oscillator-like systems are done.

  1. Twisting, supercoiling and stretching in protein bound DNA

    Science.gov (United States)

    Lam, Pui-Man; Zhen, Yi

    2018-04-01

    We have calculated theoretical results for the torque and slope of the twisted DNA, with various proteins bound on it, using the Neukirch-Marko model, in the regime where plectonemes exist. We found that the torque in the protein bound DNA decreases compared to that in the bare DNA. This is caused by the decrease in the free energy g(f) , and hence the smaller persistence lengths, in the case of protein bound DNA. We hope our results will encourage experimental investigations of supercoiling in protein bound DNA, which can provide further tests of the Neukirch-Marko model.

  2. Generalized Hofmann quantum process fidelity bounds for quantum filters

    Science.gov (United States)

    Sedlák, Michal; Fiurášek, Jaromír

    2016-04-01

    We propose and investigate bounds on the quantum process fidelity of quantum filters, i.e., probabilistic quantum operations represented by a single Kraus operator K . These bounds generalize the Hofmann bounds on the quantum process fidelity of unitary operations [H. F. Hofmann, Phys. Rev. Lett. 94, 160504 (2005), 10.1103/PhysRevLett.94.160504] and are based on probing the quantum filter with pure states forming two mutually unbiased bases. Determination of these bounds therefore requires far fewer measurements than full quantum process tomography. We find that it is particularly suitable to construct one of the probe bases from the right eigenstates of K , because in this case the bounds are tight in the sense that if the actual filter coincides with the ideal one, then both the lower and the upper bounds are equal to 1. We theoretically investigate the application of these bounds to a two-qubit optical quantum filter formed by the interference of two photons on a partially polarizing beam splitter. For an experimentally convenient choice of factorized input states and measurements we study the tightness of the bounds. We show that more stringent bounds can be obtained by more sophisticated processing of the data using convex optimization and we compare our methods for different choices of the input probe states.

  3. Bound entangled states violate a nonsymmetric local uncertainty relation

    International Nuclear Information System (INIS)

    Hofmann, Holger F.

    2003-01-01

    As a consequence of having a positive partial transpose, bound entangled states lack many of the properties otherwise associated with entanglement. It is therefore interesting to identify properties that distinguish bound entangled states from separable states. In this paper, it is shown that some bound entangled states violate a nonsymmetric class of local uncertainty relations [H. F. Hofmann and S. Takeuchi, Phys. Rev. A 68, 032103 (2003)]. This result indicates that the asymmetry of nonclassical correlations may be a characteristic feature of bound entanglement

  4. Classical Physics and the Bounds of Quantum Correlations.

    Science.gov (United States)

    Frustaglia, Diego; Baltanás, José P; Velázquez-Ahumada, María C; Fernández-Prieto, Armando; Lujambio, Aintzane; Losada, Vicente; Freire, Manuel J; Cabello, Adán

    2016-06-24

    A unifying principle explaining the numerical bounds of quantum correlations remains elusive, despite the efforts devoted to identifying it. Here, we show that these bounds are indeed not exclusive to quantum theory: for any abstract correlation scenario with compatible measurements, models based on classical waves produce probability distributions indistinguishable from those of quantum theory and, therefore, share the same bounds. We demonstrate this finding by implementing classical microwaves that propagate along meter-size transmission-line circuits and reproduce the probabilities of three emblematic quantum experiments. Our results show that the "quantum" bounds would also occur in a classical universe without quanta. The implications of this observation are discussed.

  5. Photophysics of aggregated 9-methylthiacarbocyanine bound to polyanions

    Science.gov (United States)

    Chibisov, Alexander K.; Görner, Helmut

    2002-05-01

    The photophysical properties of 3,3 '-diethyl-9-methylthiacarbocyanine (DTC) were studied in the presence of polystyrene sulfonate (PSS), polyacrylic acid (PAA) and polymethacrylic acid (PMA). The absorption spectra reflect a monomer/dimer equilibrium in neat aqueous solution and a shift towards bound H-aggregates, bound dimers and bound monomers on increasing the ratio of polyanion residue to dye concentrations ( r). These equilibria also determine the photodeactivation modes of DTC. The fluorescence intensity is reduced, when dimers and aggregates are present and strongly enhanced for low dye loading ( r=10 4). In contrast, the quantum yield of intersystem crossing is enhanced for bound dimers ( r=10 3).

  6. Accurate Open-Shell Noncovalent Interaction Energies from the Orbital-Optimized Møller-Plesset Perturbation Theory: Achieving CCSD Quality at the MP2 Level by Orbital Optimization.

    Science.gov (United States)

    Soydaş, Emine; Bozkaya, Uğur

    2013-11-12

    The accurate description of noncovalent interactions is one of the most challenging problems in modern computational chemistry, especially those for open-shell systems. In this study, an investigation of open-shell noncovalent interactions with the orbital-optimized MP2 and MP3 (OMP2 and OMP3) is presented. For the considered test set of 23 complexes, mean absolute errors in noncovalent interaction energies (with respect to CCSD(T) at complete basis set limits) are 0.68 (MP2), 0.37 (OMP2), 0.59 (MP3), 0.23 (OMP3), and 0.38 (CCSD) kcal mol(-1) . Hence, with a greatly reduced computational cost, one may achieve CCSD quality at the MP2 level by orbital optimization [scaling formally as O(N(6)) for CCSD compared to O(N(5)) for OMP2, where N is the number of basis functions]. Further, one may obtain a considerably better performance than CCSD using the OMP3 method, which has also a lower cost than CCSD.

  7. Non-covalent doping of graphitic carbon nitride with ultrathin graphene oxide and molybdenum disulfide nanosheets: an effective binary heterojunction photocatalyst under visible light irradiation.

    Science.gov (United States)

    Hu, S W; Yang, L W; Tian, Y; Wei, X L; Ding, J W; Zhong, J X; Chu, Paul K

    2014-10-01

    A proof of concept integrating binary p-n heterojunctions into a semiconductor hybrid photocatalyst is demonstrated by non-covalent doping of graphite-like carbon nitride (g-C3N4) with ultrathin GO and MoS2 nanosheets using a facile sonochemical method. In this unique ternary hybrid, the layered MoS2 and GO nanosheets with a large surface area enhance light absorption to generate more photoelectrons. On account of the coupling between MoS2 and GO with g-C3N4, the ternary hybrid possesses binary p-n heterojunctions at the g-C3N4/MoS2 and g-C3N4/GO interfaces. The space charge layers created by the p-n heterojunctions not only enhance photogeneration, but also promote charge separation and transfer of electron-hole pairs. In addition, the ultrathin MoS2 and GO with high mobility act as electron mediators to facilitate separation of photogenerated electron-hole pairs at each p-n heterojunction. As a result, the ternary hybrid photocatalyst exhibits improved photoelectrochemical and photocatalytic activity under visible light irradiation compared to other reference materials. The results provide new insights into the large-scale production of semiconductor photocatalysts. Copyright © 2014 Elsevier Inc. All rights reserved.

  8. Investigation of Non-Covalent Interactions of Aflatoxins (B1, B2, G1, G2, and M1 with Serum Albumin

    Directory of Open Access Journals (Sweden)

    Miklós Poór

    2017-10-01

    Full Text Available Aflatoxins are widely spread mycotoxins produced mainly by Aspergillus species. Consumption of aflatoxin-contaminated foods and drinks causes serious health risks for people worldwide. It is well-known that the reactive epoxide metabolite of aflatoxin B1 (AFB1 forms covalent adducts with serum albumin. However, non-covalent interactions of aflatoxins with human serum albumin (HSA are poorly characterized. Thus, in this study the complex formation of aflatoxins was examined with HSA applying spectroscopic and molecular modelling studies. Our results demonstrate that aflatoxins form stable complexes with HSA as reflected by binding constants between 2.1 × 104 and 4.5 × 104 dm3/mol. A binding free energy value of −26.90 kJ mol−1 suggests a spontaneous binding process between AFB1 and HSA at room-temperature, while the positive entropy change of 55.1 JK−1 mol−1 indicates a partial decomposition of the solvation shells of the interacting molecules. Modeling studies and investigations with site markers suggest that Sudlow’s Site I of subdomain IIA is the high affinity binding site of aflatoxins on HSA. Interaction of AFB1 with bovine, porcine, and rat serum albumins was also investigated. Similar stabilities of the examined AFB1-albumin complexes were observed suggesting the low species differences of the albumin-binding of aflatoxins.

  9. Noncovalent PEGylation: different effects of dansyl-, L-tryptophan-, phenylbutylamino-, benzyl- and cholesteryl-PEGs on the aggregation of salmon calcitonin and lysozyme.

    Science.gov (United States)

    Mueller, Claudia; Capelle, Martinus A H; Seyrek, Emek; Martel, Sophie; Carrupt, Pierre-Alain; Arvinte, Tudor; Borchard, Gerrit

    2012-06-01

    Protein aggregation is a major instability that can occur during all stages of protein drug production and development. Protein aggregates may compromise the safety and efficacy of the final protein formulation. In this paper, various new excipients [phenylbutylamino-, benzyl-, and cholesteryl-polyethylene glycols (PEGs)] and their use for the reduction of aggregation of salmon calcitonin (sCT) and hen egg-white lysozyme (HEWL) by noncovalent PEGylation are presented. The ability to suppress aggregation of sCT in various buffer systems at a 1:1 molar ratio was assessed by following changes in protein conformation and aggregation state over time. The results are compared with that of dansyl- and L-tryptophan (Trp)-PEGs described in earlier publications. Furthermore, the influence of the different PEG-based excipients on the aggregation of HEWL was measured. HEWL aggregation was completely suppressed in the presence of cholesteryl-PEGs (2 and 5 kDa), whereas deterioration was observed using benzyl-methoxy polyethylene glycols (mPEGs; 2 and 5 kDa). Phenylbutylamino- and Trp-mPEG (2 kDa), as well as dansyl-PEGs of different molecular weight prolonged the lag phase of aggregation and reduced the aggregation velocity of HEWL. Copyright © 2012 Wiley Periodicals, Inc.

  10. An Effective Approach towards the Immobilization of PtSn Nanoparticles on Noncovalent Modified Multi-Walled Carbon Nanotubes for Ethanol Electrooxidation

    Directory of Open Access Journals (Sweden)

    Xi Geng

    2016-03-01

    Full Text Available In this article, we describe an effective method to tether Pt and PtSn nanoparticles (NPs on polyelectrolyte modified multi-walled carbon nanotubes (MWCNTs for ethanol electrooxidation. By using a polymer wrapping technique, positively charged polyethyleneimine (PEI was attached onto carbon nanotubes (CNTs to provide preferential linking sites for metal precursors. Well-dispersed Pt and PtSn nanocrystals (2–5 nm were subsequently decorated on PEI-functionalized MWCNTs through the polyol reduction method. The successful non-covalent modification of MWCNTs was confirmed by Fourier transform infrared spectroscopy (FTIR and Zeta potential measurements. Energy dispersive X-ray (EDX spectrum indicates approximately 20 wt % Pt loading and a desirable Pt:Sn atomic ratio of 1:1. Electrochemical analysis demonstrated that the as-synthesized PtSn/PEI-MWCNTs nanocomposite exhibited improved catalytic activity and higher poison tolerance for ethanol oxidation as compared to Pt/PEI-MWCNTs and commercial Pt/XC-72 catalysts. The enhanced electrochemical performance may be attributed to the uniform dispersion of NPs as well as the mitigating of CO self-poisoning effect by the alloying of Sn element. This modification and synthetic strategy will be studied further to develop a diversity of carbon supported Pt-based hybrid nanomaterials for electrocatalysis.

  11. Non-Covalent Functionalisation of C30 Fullerene by Pyrrole-n-Carboxylic Acid (n=2, 3): Density Functional Theory Studies

    Science.gov (United States)

    Harismah, Kun; Mirzaei, Mahmoud; Ghasemi, Nahid; Nejati, Mohammad

    2017-12-01

    For functionalisation of a representative C30 fullerene nanostructure by pyrrole-n-carboxylic acid (PnCA; n=2, 3) their stabilities and properties were investigated based on density functional theory calculations. Parallel calculations were also done for C60 fullerene as evidence for comparing the results. Non-covalent interactions are considered to make the functionalised structures. In contrast with the spherical shape of C60, the shape of C30 fullerene is elliptical; therefore, the functionalisation processes were done for both axial and equatorial elliptical positions (AC30 and EC30). The results indicated that both the positions of C30 have almost equivalent chances to be functionalised by PnCA; but functionalisation by P2CA is slightly more favourable than P3CA, either for C60. The illustrated molecular orbitals' distributions indicated that the direction of charge transfer could be considered from PnCA counterparts to fullerene counterparts. The molecular properties indicated more reactivity for C30 than for C60 fullerene. Finally, the atomic scale quadrupole coupling constants indicated different roles for N and O atoms of PnCA in the functionalised models.

  12. A novel noncovalent complex of chorismate mutase and DAHP synthase from Mycobacterium tuberculosis: protein purification, crystallization and X-ray diffraction analysis

    International Nuclear Information System (INIS)

    Ökvist, Mats; Sasso, Severin; Roderer, Kathrin; Kast, Peter; Krengel, Ute

    2009-01-01

    Two shikimate-pathway enzymes from M. tuberculosis, the intracellular chorismate mutase (MtCM) and DAHP synthase (MtDS), were produced recombinantly and purified. MtCM was crystallized alone and in complex with MtDS and analyzed by X-ray diffraction. Chorismate mutase catalyzes a key step in the shikimate-biosynthetic pathway and hence is an essential enzyme in bacteria, plants and fungi. Mycobacterium tuberculosis contains two chorismate mutases, a secreted and an intracellular one, the latter of which (MtCM; Rv0948c; 90 amino-acid residues; 10 kDa) is the subject of this work. Here are reported the gene expression, purification and crystallization of MtCM alone and of its complex with another shikimate-pathway enzyme, DAHP synthase (MtDS; Rv2178c; 472 amino-acid residues; 52 kDa), which has been shown to enhance the catalytic efficiency of MtCM. The MtCM–MtDS complex represents the first noncovalent enzyme complex from the common shikimate pathway to be structurally characterized. Soaking experiments with a transition-state analogue are also reported. The crystals of MtCM and the MtCM–MtDS complex diffracted to 1.6 and 2.1 Å resolution, respectively

  13. A novel noncovalent complex of chorismate mutase and DAHP synthase from Mycobacterium tuberculosis: protein purification, crystallization and X-ray diffraction analysis

    Science.gov (United States)

    Ökvist, Mats; Sasso, Severin; Roderer, Kathrin; Kast, Peter; Krengel, Ute

    2009-01-01

    Chorismate mutase catalyzes a key step in the shikimate-biosynthetic pathway and hence is an essential enzyme in bacteria, plants and fungi. Mycobacterium tuberculosis contains two chorismate mutases, a secreted and an intracellular one, the latter of which (MtCM; Rv0948c; 90 amino-acid residues; 10 kDa) is the subject of this work. Here are reported the gene expression, purification and crystallization of MtCM alone and of its complex with another shikimate-pathway enzyme, DAHP synthase (MtDS; Rv2178c; 472 amino-acid residues; 52 kDa), which has been shown to enhance the catalytic efficiency of MtCM. The MtCM–MtDS complex represents the first noncovalent enzyme complex from the common shikimate pathway to be structurally characterized. Soaking experiments with a transition-state analogue are also reported. The crystals of MtCM and the MtCM–MtDS complex diffracted to 1.6 and 2.1 Å resolution, respectively. PMID:19851019

  14. Non-covalent functionalisation of C{sub 30} fullerene by pyrrole-n-carboxylic acid (n=2, 3). Density functional theory studies

    Energy Technology Data Exchange (ETDEWEB)

    Harismah, Kun [Univ. Muhammadiyah Surakarta (Indonesia). Dept. of Chemical Engineering; Mirzaei, Mahmoud [Isfahan Univ. of Medical Sciences (Iran, Islamic Republic of). Bioinformatics Research Center; Ghasemi, Nahid [Islamic Azad Univ., Arak (Iran, Islamic Republic of). Dept. of Chemistry; Nejati, Mohammad [Islamic Azad Univ., Tehran (Iran, Islamic Republic of). Dept. of Chemistry

    2018-04-01

    For functionalisation of a representative C{sub 30} fullerene nanostructure by pyrrole-n-carboxylic acid (PnCA; n=2, 3) their stabilities and properties were investigated based on density functional theory calculations. Parallel calculations were also done for C{sub 60} fullerene as evidence for comparing the results. Non-covalent interactions are considered to make the functionalised structures. In contrast with the spherical shape of C{sub 60}, the shape of C{sub 30} fullerene is elliptical; therefore, the functionalisation processes were done for both axial and equatorial elliptical positions (AC{sub 30} and EC{sub 30}). The results indicated that both the positions of C{sub 30} have almost equivalent chances to be functionalised by PnCA; but functionalisation by P2CA is slightly more favourable than P3CA, either for C{sub 60}. The illustrated molecular orbitals' distributions indicated that the direction of charge transfer could be considered from PnCA counterparts to fullerene counterparts. The molecular properties indicated more reactivity for C{sub 30} than for C{sub 60} fullerene. Finally, the atomic scale quadrupole coupling constants indicated different roles for N and O atoms of PnCA in the functionalised models.

  15. Host-Guest Complexes of Cyclodextrins and Nanodiamonds as a Strong Non-Covalent Binding Motif for Self-Assembled Nanomaterials.

    Science.gov (United States)

    Schibilla, Frauke; Voskuhl, Jens; Fokina, Natalie A; Dahl, Jeremy E P; Schreiner, Peter R; Ravoo, Bart Jan

    2017-11-13

    We report the inclusion of carboxy- and amine-substituted molecular nanodiamonds (NDs) adamantane, diamantane, and triamantane by β-cyclodextrin and γ-cyclodextrin (β-CD and γ-CD), which have particularly well-suited hydrophobicity and symmetry for an optimal fit of the host and guest molecules. We studied the host-guest interactions in detail and generally observed 1:1 association of the NDs with the larger γ-CD cavity, but observed 1:2 association for the largest ND in the series (triamantane) with β-CD. We found higher binding affinities for carboxy-substituted NDs than for amine-substituted NDs. Additionally, cyclodextrin vesicles (CDVs) were decorated with d-mannose by using adamantane, diamantane, and triamantane as non-covalent anchors, and the resulting vesicles were compared with the lectin concanavalin A in agglutination experiments. Agglutination was directly correlated to the host-guest association: adamantane showed lower agglutination than di- or triamantane with β-CDV and almost no agglutination with γ-CDV, whereas high agglutination was observed for di- and triamantane with γ-CDV. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Non-covalently anchored multi-walled carbon nanotubes with hexa-decafluorinated zinc phthalocyanine as ppb level chemiresistive chlorine sensor

    Science.gov (United States)

    Sharma, Anshul Kumar; Mahajan, Aman; Bedi, R. K.; Kumar, Subodh; Debnath, A. K.; Aswal, D. K.

    2018-01-01

    A cost effective solution assembly method has been explored for preparing zinc(II)1,2,3,4,8,9,10,11,15,16,17,18,22,23,24,25-hexa-decafluoro-29H,31H-phthalocyanine/multi-walled carbon nanotubes (F16ZnPc/MWCNTs-COOH) hybrid. Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, transmission electron microscopy (TEM) and field emission scanning electron microscopy (FE-SEM) investigations confirm the non-covalent anchoring of F16ZnPc onto MWCNTs-COOH through п-п stacking interactions. Further, a highly sensitive and selective chemiresistive Cl2 sensor has been fabricated using F16ZnPc/MWCNTs-COOH hybrid. The response of sensor is found to be 21.28% for 2 ppm of Cl2 with a response time of 14 s and theoretical detection limit of the sensor is found down to 0.06 ppb. The improved Cl2 sensing characteristics of hybrid are found to be originated from the synergetic interaction between F16ZnPc and MWCNTs-COOH. The underlying mechanism for improved gas sensing performance of F16ZnPc/MWCNTs-COOH sensor towards Cl2 has been explained using Raman, X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS) studies.

  17. Sea level: measuring the bounding surfaces of the ocean

    Science.gov (United States)

    Tamisiea, Mark E.; Hughes, Chris W.; Williams, Simon D. P.; Bingley, Richard M.

    2014-01-01

    The practical need to understand sea level along the coasts, such as for safe navigation given the spatially variable tides, has resulted in tide gauge observations having the distinction of being some of the longest instrumental ocean records. Archives of these records, along with geological constraints, have allowed us to identify the century-scale rise in global sea level. Additional data sources, particularly satellite altimetry missions, have helped us to better identify the rates and causes of sea-level rise and the mechanisms leading to spatial variability in the observed rates. Analysis of all of the data reveals the need for long-term and stable observation systems to assess accurately the regional changes as well as to improve our ability to estimate future changes in sea level. While information from many scientific disciplines is needed to understand sea-level change, this review focuses on contributions from geodesy and the role of the ocean's bounding surfaces: the sea surface and the Earth's crust. PMID:25157196

  18. Sea level: measuring the bounding surfaces of the ocean.

    Science.gov (United States)

    Tamisiea, Mark E; Hughes, Chris W; Williams, Simon D P; Bingley, Richard M

    2014-09-28

    The practical need to understand sea level along the coasts, such as for safe navigation given the spatially variable tides, has resulted in tide gauge observations having the distinction of being some of the longest instrumental ocean records. Archives of these records, along with geological constraints, have allowed us to identify the century-scale rise in global sea level. Additional data sources, particularly satellite altimetry missions, have helped us to better identify the rates and causes of sea-level rise and the mechanisms leading to spatial variability in the observed rates. Analysis of all of the data reveals the need for long-term and stable observation systems to assess accurately the regional changes as well as to improve our ability to estimate future changes in sea level. While information from many scientific disciplines is needed to understand sea-level change, this review focuses on contributions from geodesy and the role of the ocean's bounding surfaces: the sea surface and the Earth's crust. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  19. Dynamic nuclear polarization of nucleic acid with endogenously bound manganese

    International Nuclear Information System (INIS)

    Wenk, Patricia; Kaushik, Monu; Richter, Diane; Vogel, Marc; Suess, Beatrix; Corzilius, Björn

    2015-01-01

    We report the direct dynamic nuclear polarization (DNP) of 13 C nuclei of a uniformly [ 13 C, 15 N]-labeled, paramagnetic full-length hammerhead ribozyme (HHRz) complex with Mn 2+ where the enhanced polarization is fully provided by the endogenously bound metal ion and no exogenous polarizing agent is added. A 13 C enhancement factor of ε = 8 was observed by intra-complex DNP at 9.4 T. In contrast, “conventional” indirect and direct DNP experiments were performed using AMUPol as polarizing agent where we obtained a 1 H enhancement factor of ε ≈ 250. Comparison with the diamagnetic (Mg 2+ ) HHRz complex shows that the presence of Mn 2+ only marginally influences the (DNP-enhanced) NMR properties of the RNA. Furthermore two-dimensional correlation spectra ( 15 N– 13 C and 13 C– 13 C) reveal structural inhomogeneity in the frozen, amorphous state indicating the coexistence of several conformational states. These demonstrations of intra-complex DNP using an endogenous metal ion as well as DNP-enhanced MAS NMR of RNA in general yield important information for the development of new methods in structural biology

  20. Dynamic nuclear polarization of nucleic acid with endogenously bound manganese

    Energy Technology Data Exchange (ETDEWEB)

    Wenk, Patricia [University of Tübingen, Werner Siemens Imaging Center and Department of Preclinical Imaging and Radiopharmacy (Germany); Kaushik, Monu; Richter, Diane [Goethe University, Institute of Physical und Theoretical Chemistry, Institute of Biophysical Chemistry und Center for Biomolecular Magnetic Resonance (BMRZ) (Germany); Vogel, Marc; Suess, Beatrix [Technical University Darmstadt, Department of Biology (Germany); Corzilius, Björn, E-mail: corzilius@em.uni-frankfurt.de [Goethe University, Institute of Physical und Theoretical Chemistry, Institute of Biophysical Chemistry und Center for Biomolecular Magnetic Resonance (BMRZ) (Germany)

    2015-09-15

    We report the direct dynamic nuclear polarization (DNP) of {sup 13}C nuclei of a uniformly [{sup 13}C,{sup 15}N]-labeled, paramagnetic full-length hammerhead ribozyme (HHRz) complex with Mn{sup 2+} where the enhanced polarization is fully provided by the endogenously bound metal ion and no exogenous polarizing agent is added. A {sup 13}C enhancement factor of ε = 8 was observed by intra-complex DNP at 9.4 T. In contrast, “conventional” indirect and direct DNP experiments were performed using AMUPol as polarizing agent where we obtained a {sup 1}H enhancement factor of ε ≈ 250. Comparison with the diamagnetic (Mg{sup 2+}) HHRz complex shows that the presence of Mn{sup 2+} only marginally influences the (DNP-enhanced) NMR properties of the RNA. Furthermore two-dimensional correlation spectra ({sup 15}N–{sup 13}C and {sup 13}C–{sup 13}C) reveal structural inhomogeneity in the frozen, amorphous state indicating the coexistence of several conformational states. These demonstrations of intra-complex DNP using an endogenous metal ion as well as DNP-enhanced MAS NMR of RNA in general yield important information for the development of new methods in structural biology.