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Sample records for chemical shift correlation

  1. Effects of Protein-pheromone Complexation on Correlated Chemical Shift Modulations

    Energy Technology Data Exchange (ETDEWEB)

    Perazzolo, Chiara; Wist, Julien [Ecole Polytechnique Federale de Lausanne, Institut des Sciences et Ingenierie Chimiques (Switzerland); Loth, Karine; Poggi, Luisa [Ecole Normale Superieure, Departement de chimie, associe au CNRS (France); Homans, Steve [University of Leeds, School of Biochemistry and Microbiology (United Kingdom); Bodenhausen, Geoffrey [Ecole Polytechnique Federale de Lausanne, Institut des Sciences et Ingenierie Chimiques (Switzerland)], E-mail: Geoffrey.Bodenhausen@ens.fr

    2005-12-15

    Major urinary protein (MUP) is a pheromone-carrying protein of the lipocalin family. Previous studies by isothermal titration calorimetry (ITC) show that the affinity of MUP for the pheromone 2-methoxy-3-isobutylpyrazine (IBMP) is mainly driven by enthalpy, with a small unfavourable entropic contribution. Entropic terms can be attributed in part to changes in internal motions of the protein upon binding. Slow internal motions can lead to correlated or anti-correlated modulations of the isotropic chemical shifts of carbonyl C' and amide N nuclei. Correlated chemical shift modulations (CSM/CSM) in MUP have been determined by measuring differences of the transverse relaxation rates of zero- and double-quantum coherences ZQC{l_brace}C'N{r_brace} and DQC{l_brace}C'N{r_brace}, and by accounting for the effects of correlated fluctuations of dipole-dipole couplings (DD/DD) and chemical shift anisotropies (CSA/CSA). The latter can be predicted from tensor parameters of C' and N nuclei that have been determined in earlier work. The effects of complexation on slow time-scale protein dynamics can be determined by comparing the temperature dependence of the relaxation rates of APO-MUP (i.e., without ligand) and HOLO-MUP (i.e., with IBMP as a ligand)

  2. Correlation of chemical shifts predicted by molecular dynamics simulations for partially disordered proteins

    Energy Technology Data Exchange (ETDEWEB)

    Karp, Jerome M.; Erylimaz, Ertan; Cowburn, David, E-mail: cowburn@cowburnlab.org, E-mail: David.cowburn@einstein.yu.edu [Albert Einstein College of Medicine of Yeshiva University, Department of Biochemistry (United States)

    2015-01-15

    There has been a longstanding interest in being able to accurately predict NMR chemical shifts from structural data. Recent studies have focused on using molecular dynamics (MD) simulation data as input for improved prediction. Here we examine the accuracy of chemical shift prediction for intein systems, which have regions of intrinsic disorder. We find that using MD simulation data as input for chemical shift prediction does not consistently improve prediction accuracy over use of a static X-ray crystal structure. This appears to result from the complex conformational ensemble of the disordered protein segments. We show that using accelerated molecular dynamics (aMD) simulations improves chemical shift prediction, suggesting that methods which better sample the conformational ensemble like aMD are more appropriate tools for use in chemical shift prediction for proteins with disordered regions. Moreover, our study suggests that data accurately reflecting protein dynamics must be used as input for chemical shift prediction in order to correctly predict chemical shifts in systems with disorder.

  3. Sequential acquisition of multi-dimensional heteronuclear chemical shift correlation spectra with 1H detection

    Science.gov (United States)

    Bellstedt, Peter; Ihle, Yvonne; Wiedemann, Christoph; Kirschstein, Anika; Herbst, Christian; Görlach, Matthias; Ramachandran, Ramadurai

    2014-03-01

    RF pulse schemes for the simultaneous acquisition of heteronuclear multi-dimensional chemical shift correlation spectra, such as {HA(CA)NH & HA(CACO)NH}, {HA(CA)NH & H(N)CAHA} and {H(N)CAHA & H(CC)NH}, that are commonly employed in the study of moderately-sized protein molecules, have been implemented using dual sequential 1H acquisitions in the direct dimension. Such an approach is not only beneficial in terms of the reduction of experimental time as compared to data collection via two separate experiments but also facilitates the unambiguous sequential linking of the backbone amino acid residues. The potential of sequential 1H data acquisition procedure in the study of RNA is also demonstrated here.

  4. Correlation of 1H NMR Chemical Shift for Aqueous Solutions by Statistical Associating Fluid Theory Association Model

    Institute of Scientific and Technical Information of China (English)

    许波; 李浩然; 王从敏; 许映杰; 韩世钧

    2005-01-01

    1H NMR chemical shifts of binary aqueous mixtures of acylamide, alcohol, dimethyl sulphoxide (DMSO), and acetone are correlated by statistical associating fluid theory (SAFT) association model. The comparison between SAFT association model and Wilson equation shows that the former is better for dealing with aqueous solutions. Finally, the specialties of both models are discussed.

  5. A NMR experiment for simultaneous correlations of valine and leucine/isoleucine methyls with carbonyl chemical shifts in proteins.

    Science.gov (United States)

    Tugarinov, Vitali; Venditti, Vincenzo; Marius Clore, G

    2014-01-01

    A methyl-detected 'out-and-back' NMR experiment for obtaining simultaneous correlations of methyl resonances of valine and isoleucine/leucine residues with backbone carbonyl chemical shifts, SIM-HMCM(CGCBCA)CO, is described. The developed pulse-scheme serves the purpose of convenience in recording a single data set for all Ile(δ1), Leu(δ) and Val(γ) (ILV) methyl positions instead of acquiring two separate spectra selective for valine or leucine/isoleucine residues. The SIM-HMCM(CGCBCA)CO experiment can be used for ILV methyl assignments in moderately sized protein systems (up to ~100 kDa) where the backbone chemical shifts of (13)C(α), (13)Cβ and (13)CO are known from prior NMR studies and where some losses in sensitivity can be tolerated for the sake of an overall reduction in NMR acquisition time.

  6. Protein Chemical Shift Prediction

    CERN Document Server

    Larsen, Anders S

    2014-01-01

    The protein chemical shifts holds a large amount of information about the 3-dimensional structure of the protein. A number of chemical shift predictors based on the relationship between structures resolved with X-ray crystallography and the corresponding experimental chemical shifts have been developed. These empirical predictors are very accurate on X-ray structures but tends to be insensitive to small structural changes. To overcome this limitation it has been suggested to make chemical shift predictors based on quantum mechanical(QM) calculations. In this thesis the development of the QM derived chemical shift predictor Procs14 is presented. Procs14 is based on 2.35 million density functional theory(DFT) calculations on tripeptides and contains corrections for hydrogen bonding, ring current and the effect of the previous and following residue. Procs14 is capable at performing predictions for the 13CA, 13CB, 13CO, 15NH, 1HN and 1HA backbone atoms. In order to benchmark Procs14, a number of QM NMR calculatio...

  7. Halodemetallation of (Z)-1-[2-(Triarylstannyl)vinyl]-cyclooctanol and Correlation of Proton Chemical Shift with Electronegativity

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    @@ Introduction Organotin compounds have attracted attention as an optimal model for antitumour agents due to the function of the interesting intramolecular O→Sn coordination[1,2]. Our recent concern has been focused on the preparation of (Z)-1-[2-(triarylstannyl)vinyl]-cyclooctanol[3]. In order to find more appropriate compounds used as anticancer agents and explore the effect of the coordinate O→Sn interaction to the antitumor activity, the new compounds were halodemetallated and characterized. During the course of the process, some linear correlations between proton chemical shifts and the sum of the electronegativities of the tin substituents of halogens were found for the first time.

  8. Sequence correction of random coil chemical shifts: correlation between neighbor correction factors and changes in the Ramachandran distribution

    DEFF Research Database (Denmark)

    Kjærgaard, Magnus; Poulsen, Flemming Martin

    2011-01-01

    Random coil chemical shifts are necessary for secondary chemical shift analysis, which is the main NMR method for identification of secondary structure in proteins. One of the largest challenges in the determination of random coil chemical shifts is accounting for the effect of neighboring residues....... The contributions from the neighboring residues are typically removed by using neighbor correction factors determined based on each residue's effect on glycine chemical shifts. Due to its unusual conformational freedom, glycine may be particularly unrepresentative for the remaining residue types. In this study, we...... in the conformational ensemble are an important source of neighbor effects in disordered proteins. Glutamine derived random coil chemical shifts and correction factors modestly improve our ability to predict (13)C chemical shifts of intrinsically disordered proteins compared to existing datasets, and may thus improve...

  9. Indirectly detected chemical shift correlation NMR spectroscopy in solids under fast magic angle spinning

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Kanmi [Iowa State Univ., Ames, IA (United States)

    2011-01-01

    The development of fast magic angle spinning (MAS) opened up an opportunity for the indirect detection of insensitive low-γ nuclei (e.g., 13C and 15N) via the sensitive high-{gamma} nuclei (e.g., 1H and 19F) in solid-state NMR, with advanced sensitivity and resolution. In this thesis, new methodology utilizing fast MAS is presented, including through-bond indirectly detected heteronuclear correlation (HETCOR) spectroscopy, which is assisted by multiple RF pulse sequences for 1H-1H homonuclear decoupling. Also presented is a simple new strategy for optimization of 1H-1H homonuclear decoupling. As applications, various classes of materials, such as catalytic nanoscale materials, biomolecules, and organic complexes, are studied by combining indirect detection and other one-dimensional (1D) and two-dimensional (2D) NMR techniques. Indirectly detected through-bond HETCOR spectroscopy utilizing refocused INEPT (INEPTR) mixing was developed under fast MAS (Chapter 2). The time performance of this approach in 1H detected 2D 1H{l_brace}13C{r_brace} spectra was significantly improved, by a factor of almost 10, compared to the traditional 13C detected experiments, as demonstrated by measuring naturally abundant organic-inorganic mesoporous hybrid materials. The through-bond scheme was demonstrated as a new analytical tool, which provides complementary structural information in solid-state systems in addition to through-space correlation. To further benefit the sensitivity of the INEPT transfer in rigid solids, the combined rotation and multiple-pulse spectroscopy (CRAMPS) was implemented for homonuclear 1H decoupling under fast MAS (Chapter 3). Several decoupling schemes (PMLG5m$\\bar{x}$, PMLG5mm$\\bar{x}$x and SAM3) were analyzed to maximize the performance of through-bond transfer based

  10. Solid state NMR of proteins at high MAS frequencies: symmetry-based mixing and simultaneous acquisition of chemical shift correlation spectra

    Energy Technology Data Exchange (ETDEWEB)

    Bellstedt, Peter [Fritz Lipmann Institute, Biomolecular NMR spectroscopy, Leibniz Institute for Age Research (Germany); Herbst, Christian [Ubon Ratchathani University, Department of Physics, Faculty of Science (Thailand); Haefner, Sabine; Leppert, Joerg; Goerlach, Matthias; Ramachandran, Ramadurai, E-mail: raman@fli-leibniz.de [Fritz Lipmann Institute, Biomolecular NMR spectroscopy, Leibniz Institute for Age Research (Germany)

    2012-12-15

    We have carried out chemical shift correlation experiments with symmetry-based mixing sequences at high MAS frequencies and examined different strategies to simultaneously acquire 3D correlation spectra that are commonly required in the structural studies of proteins. The potential of numerically optimised symmetry-based mixing sequences and the simultaneous recording of chemical shift correlation spectra such as: 3D NCAC and 3D NHH with dual receivers, 3D NC Prime C and 3D C Prime NCA with sequential {sup 13}C acquisitions, 3D NHH and 3D NC Prime H with sequential {sup 1}H acquisitions and 3D CANH and 3D C'NH with broadband {sup 13}C-{sup 15}N mixing are demonstrated using microcrystalline samples of the {beta}1 immunoglobulin binding domain of protein G (GB1) and the chicken {alpha}-spectrin SH3 domain.

  11. Proton-detected 3D (15)N/(1)H/(1)H isotropic/anisotropic/isotropic chemical shift correlation solid-state NMR at 70kHz MAS.

    Science.gov (United States)

    Pandey, Manoj Kumar; Yarava, Jayasubba Reddy; Zhang, Rongchun; Ramamoorthy, Ayyalusamy; Nishiyama, Yusuke

    2016-01-01

    Chemical shift anisotropy (CSA) tensors offer a wealth of information for structural and dynamics studies of a variety of chemical and biological systems. In particular, CSA of amide protons can provide piercing insights into hydrogen-bonding interactions that vary with the backbone conformation of a protein and dynamics. However, the narrow span of amide proton resonances makes it very difficult to measure (1)H CSAs of proteins even by using the recently proposed 2D (1)H/(1)H anisotropic/isotropic chemical shift (CSA/CS) correlation technique. Such difficulties due to overlapping proton resonances can in general be overcome by utilizing the broad span of isotropic chemical shifts of low-gamma nuclei like (15)N. In this context, we demonstrate a proton-detected 3D (15)N/(1)H/(1)H CS/CSA/CS correlation experiment at fast MAS frequency (70kHz) to measure (1)H CSA values of unresolved amide protons of N-acetyl-(15)N-l-valyl-(15)N-l-leucine (NAVL).

  12. Homonuclear chemical shift correlation in rotating solids via RN{sup {nu}}{sub n} symmetry-based adiabatic RF pulse schemes

    Energy Technology Data Exchange (ETDEWEB)

    Riedel, Kerstin; Leppert, Joerg; Haefner, Sabine; Ohlenschlaeger, Oliver; Goerlach, Matthias; Ramachandran, Ramadurai [Institut fuer Molekulare Biotechnologie, Abteilung Molekulare Biophysik/NMR-Spektroskopie (Germany)], E-mail: raman@imb-jena.de

    2004-12-15

    The efficacy of RN{sup {nu}}{sub n} symmetry-based adiabatic Zero-Quantum (ZQ) dipolar recoupling schemes for obtaining chemical shift correlation data at moderate magic angle spinning frequencies has been evaluated. RN{sub n}{sup {nu}} sequences generally employ basic inversion elements that correspond to a net 180 deg. rotation about the rotating frame x-axis. It is shown here via numerical simulations and experimental measurements that it is also possible to achieve efficient ZQ dipolar recoupling via RN{sub n}{sup {nu}} schemes employing adiabatic pulses. Such an approach was successfully used for obtaining {sup 1}3C chemical shift correlation spectra of a uniformly labelled sample of (CUG){sub 9}7- a triplet repeat expansion RNA that has been implicated in the neuromuscular disease myotonic dystrophy. An analysis of the {sup 1}3C sugar carbon chemical shifts suggests, in agreement with our recent {sup 1}5N MAS-NMR studies, that this RNA adopts an A-helical conformation.

  13. Empirical isotropic chemical shift surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Czinki, Eszter; Csaszar, Attila G. [Eoetvoes University, Laboratory of Molecular Spectroscopy, Institute of Chemistry (Hungary)], E-mail: csaszar@chem.elte.hu

    2007-08-15

    A list of proteins is given for which spatial structures, with a resolution better than 2.5 A, are known from entries in the Protein Data Bank (PDB) and isotropic chemical shift (ICS) values are known from the RefDB database related to the Biological Magnetic Resonance Bank (BMRB) database. The structures chosen provide, with unknown uncertainties, dihedral angles {phi} and {psi} characterizing the backbone structure of the residues. The joint use of experimental ICSs of the same residues within the proteins, again with mostly unknown uncertainties, and ab initio ICS({phi},{psi}) surfaces obtained for the model peptides For-(l-Ala){sub n}-NH{sub 2}, with n = 1, 3, and 5, resulted in so-called empirical ICS({phi},{psi}) surfaces for all major nuclei of the 20 naturally occurring {alpha}-amino acids. Out of the many empirical surfaces determined, it is the 13C{sup {alpha}} ICS({phi},{psi}) surface which seems to be most promising for identifying major secondary structure types, {alpha}-helix, {beta}-strand, left-handed helix ({alpha}{sub D}), and polyproline-II. Detailed tests suggest that Ala is a good model for many naturally occurring {alpha}-amino acids. Two-dimensional empirical 13C{sup {alpha}}-{sup 1}H{sup {alpha}} ICS({phi},{psi}) correlation plots, obtained so far only from computations on small peptide models, suggest the utility of the experimental information contained therein and thus they should provide useful constraints for structure determinations of proteins.

  14. Correlations of the chemical shift on fasly rotating biological solids by means of NMR spectroscopy; Korrelationen der chemischen Verschiebung an schnell rotierenden biologischen Festkoerpern mittels NMR-Spektroskopie

    Energy Technology Data Exchange (ETDEWEB)

    Herbst, Christian

    2010-04-27

    The basic aim of the thesis was the development and improvement of homo- and heteronuclear feedback sequences for the generation of correlation spectra of the chemical shift. In a first step the possibility of the acquisition of {sup 13}C-{sup 13} correlation spectra of the chemical shift by means of inversion pulses with low RF power factor was studied. Furthermore it was shown that broad-band phase-modulated inversion and universal rotational pulses can be constructed by means of global optimization procedures like the genetic algorithms under regardment of the available RF field strength. By inversion, universal rotational, and 360 pulses as starting values of the optimization efficient homonuclear CN{sub n}{sup {nu}} and RN{sub n}{sup {nu}} mixing sequences as well as heteronuclear RN{sub n}{sup {nu}{sub s},{nu}{sub k}} feedback sequences were generated. The satisfactory power of the numerically optimized sequences was shown by means of the simulation as well by means of correlation experiments of the chemical shift of L-histidine, L-arginine, and the (CUG){sub 97}-RNA. This thesis deals furthermore with the possibility to acquire simultaneously different signals with several receivers. By means of numerically optimized RN{sub n}{sup {nu}{sub s},{nu}{sub k}} pulse sequences both {sup 15}N-{sup 13}C and {sup 13}C-{sup 15}N correlation spectra were simultaneously generated. Furthermore it could be shown that the simultaneous acquisition of 3D-{sup 15}N-{sup 13}C-{sup 13}C and {sup 13}C-{sup 15}N-({sup 1}H)-{sup 1}H correlation spectra is possible. By this in only one measurement process resonance assignments can be met and studies of the global folding performed. A further application of several receivers is the simultaneous acquisition of CHHC, NHHN, NHHC, as well as CHHN spectra. By such experiments it is possible to characterize the hydrogen-bonding pattern and the glycosidic torsion angle {sup {chi}} in RNA. This was demonstrated by means of the (CUG){sub 97

  15. Chemical shift prediction for denatured proteins

    Energy Technology Data Exchange (ETDEWEB)

    Prestegard, James H., E-mail: jpresteg@ccrc.uga.edu; Sahu, Sarata C.; Nkari, Wendy K.; Morris, Laura C.; Live, David; Gruta, Christian

    2013-02-15

    While chemical shift prediction has played an important role in aspects of protein NMR that include identification of secondary structure, generation of torsion angle constraints for structure determination, and assignment of resonances in spectra of intrinsically disordered proteins, interest has arisen more recently in using it in alternate assignment strategies for crosspeaks in {sup 1}H-{sup 15}N HSQC spectra of sparsely labeled proteins. One such approach involves correlation of crosspeaks in the spectrum of the native protein with those observed in the spectrum of the denatured protein, followed by assignment of the peaks in the latter spectrum. As in the case of disordered proteins, predicted chemical shifts can aid in these assignments. Some previously developed empirical formulas for chemical shift prediction have depended on basis data sets of 20 pentapeptides. In each case the central residue was varied among the 20 amino common acids, with the flanking residues held constant throughout the given series. However, previous choices of solvent conditions and flanking residues make the parameters in these formulas less than ideal for general application to denatured proteins. Here, we report {sup 1}H and {sup 15}N shifts for a set of alanine based pentapeptides under the low pH urea denaturing conditions that are more appropriate for sparse label assignments. New parameters have been derived and a Perl script was created to facilitate comparison with other parameter sets. A small, but significant, improvement in shift predictions for denatured ubiquitin is demonstrated.

  16. Accessible surface area from NMR chemical shifts

    Energy Technology Data Exchange (ETDEWEB)

    Hafsa, Noor E.; Arndt, David; Wishart, David S., E-mail: david.wishart@ualberta.ca [University of Alberta, Department of Computing Science (Canada)

    2015-07-15

    Accessible surface area (ASA) is the surface area of an atom, amino acid or biomolecule that is exposed to solvent. The calculation of a molecule’s ASA requires three-dimensional coordinate data and the use of a “rolling ball” algorithm to both define and calculate the ASA. For polymers such as proteins, the ASA for individual amino acids is closely related to the hydrophobicity of the amino acid as well as its local secondary and tertiary structure. For proteins, ASA is a structural descriptor that can often be as informative as secondary structure. Consequently there has been considerable effort over the past two decades to try to predict ASA from protein sequence data and to use ASA information (derived from chemical modification studies) as a structure constraint. Recently it has become evident that protein chemical shifts are also sensitive to ASA. Given the potential utility of ASA estimates as structural constraints for NMR we decided to explore this relationship further. Using machine learning techniques (specifically a boosted tree regression model) we developed an algorithm called “ShiftASA” that combines chemical-shift and sequence derived features to accurately estimate per-residue fractional ASA values of water-soluble proteins. This method showed a correlation coefficient between predicted and experimental values of 0.79 when evaluated on a set of 65 independent test proteins, which was an 8.2 % improvement over the next best performing (sequence-only) method. On a separate test set of 92 proteins, ShiftASA reported a mean correlation coefficient of 0.82, which was 12.3 % better than the next best performing method. ShiftASA is available as a web server ( http://shiftasa.wishartlab.com http://shiftasa.wishartlab.com ) for submitting input queries for fractional ASA calculation.

  17. Protein Structure Determination Using Chemical Shifts

    DEFF Research Database (Denmark)

    Christensen, Anders Steen

    In this thesis, a protein structure determination using chemical shifts is presented. The method is implemented in the open source PHAISTOS protein simulation framework. The method combines sampling from a generative model with a coarse-grained force field and an energy function that includes...... chemical shifts. The method is benchmarked on folding simulations of five small proteins. In four cases the resulting structures are in excellent agreement with experimental data, the fifth case fail likely due to inaccuracies in the energy function. For the Chymotrypsin Inhibitor protein, a structure...... is determined using only chemical shifts recorded and assigned through automated processes. The CARMSD to the experimental X-ray for this structure is 1.1. Å. Additionally, the method is combined with very sparse NOE-restraints and evolutionary distance restraints and tested on several protein structures >100...

  18. Random coil chemical shift for intrinsically disordered proteins

    DEFF Research Database (Denmark)

    Kjærgaard, Magnus; Brander, Søren; Poulsen, Flemming Martin

    2011-01-01

    . Temperature has a non-negligible effect on the (13)C random coil chemical shifts, so temperature coefficients are reported for the random coil chemical shifts to allow extrapolation to other temperatures. The pH dependence of the histidine random coil chemical shifts is investigated in a titration series......, which allows the accurate random coil chemical shifts to be obtained at any pH. By correcting the random coil chemical shifts for the effects of temperature and pH, systematic biases of the secondary chemical shifts are minimized, which will improve the reliability of detection of transient secondary...

  19. Chemical-shift-resolved ¹⁹F NMR spectroscopy between 13.5 and 135 MHz: Overhauser-DNP-enhanced diagonal suppressed correlation spectroscopy.

    Science.gov (United States)

    George, Christy; Chandrakumar, Narayanan

    2014-08-01

    Overhauser-DNP-enhanced homonuclear 2D (19)F correlation spectroscopy with diagonal suppression is presented for small molecules in the solution state at moderate fields. Multi-frequency, multi-radical studies demonstrate that these relatively low-field experiments may be operated with sensitivity rivalling that of standard 200-1000 MHz NMR spectroscopy. Structural information is accessible without a sensitivity penalty, and diagonal suppressed 2D NMR correlations emerge despite the general lack of multiplet resolution in the 1D ODNP spectra. This powerful general approach avoids the rather stiff excitation, detection, and other special requirements of high-field (19)F NMR spectroscopy.

  20. Correlation of Fe2+ isomer shifts with bond lengths and bond strengths in neso- and sorosilicates

    Institute of Scientific and Technical Information of China (English)

    李哲; E.DeGrave

    1995-01-01

    An evaluation of Mbssbauer isomer shift and quadrupole splitting data of Fe2+ in a number of structurally well characterized neso- and sorosilicates is presented. It is found that the nearly linear correlations exist both between the isomer shift and the bond length and between the isomer shift and the bond strength. These correlations are discussed on the basis of the variation of the s-electron density at the Fe2+ nuclei with the chemical bond characteristics.

  1. Cross-Correlated Relaxation of Dipolar Coupling and Chemical-Shift Anisotropy in Magic-Angle Spinning R1ρ NMR Measurements: Application to Protein Backbone Dynamics Measurements.

    Science.gov (United States)

    Kurauskas, Vilius; Weber, Emmanuelle; Hessel, Audrey; Ayala, Isabel; Marion, Dominique; Schanda, Paul

    2016-09-01

    Transverse relaxation rate measurements in magic-angle spinning solid-state nuclear magnetic resonance provide information about molecular motions occurring on nanosecond-to-millisecond (ns-ms) time scales. The measurement of heteronuclear ((13)C, (15)N) relaxation rate constants in the presence of a spin-lock radiofrequency field (R1ρ relaxation) provides access to such motions, and an increasing number of studies involving R1ρ relaxation in proteins have been reported. However, two factors that influence the observed relaxation rate constants have so far been neglected, namely, (1) the role of CSA/dipolar cross-correlated relaxation (CCR) and (2) the impact of fast proton spin flips (i.e., proton spin diffusion and relaxation). We show that CSA/D CCR in R1ρ experiments is measurable and that the CCR rate constant depends on ns-ms motions; it can thus provide insight into dynamics. We find that proton spin diffusion attenuates this CCR due to its decoupling effect on the doublet components. For measurements of dynamics, the use of R1ρ rate constants has practical advantages over the use of CCR rates, and this article reveals factors that have so far been disregarded and which are important for accurate measurements and interpretation.

  2. Relationship between chemical shift value and accessible surface area for all amino acid atoms

    Directory of Open Access Journals (Sweden)

    Rieping Wolfgang

    2009-04-01

    Full Text Available Abstract Background Chemical shifts obtained from NMR experiments are an important tool in determining secondary, even tertiary, protein structure. The main repository for chemical shift data is the BioMagResBank, which provides NMR-STAR files with this type of information. However, it is not trivial to link this information to available coordinate data from the PDB for non-backbone atoms due to atom and chain naming differences, as well as sequence numbering changes. Results We here describe the analysis of a consistent set of chemical shift and coordinate data, in which we focus on the relationship between the per-atom solvent accessible surface area (ASA in the reported coordinates and their reported chemical shift value. The data is available online on http://www.ebi.ac.uk/pdbe/docs/NMR/shiftAnalysis/index.html. Conclusion Atoms with zero per-atom ASA have a significantly larger chemical shift dispersion and often have a different chemical shift distribution compared to those that are solvent accessible. With higher per-atom ASA, the chemical shift values also tend towards random coil values. The per-atom ASA, although not the determinant of the chemical shift, thus provides a way to directly correlate chemical shift information to the atomic coordinates.

  3. Collisionally induced atomic clock shifts and correlations

    Energy Technology Data Exchange (ETDEWEB)

    Band, Y. B.; Osherov, I. [Departments of Chemistry and Electro-Optics and the Ilse Katz Center for Nano-Science, Ben-Gurion University, Beer-Sheva 84105 (Israel)

    2011-07-15

    We develop a formalism to incorporate exchange symmetry considerations into the calculation of collisional frequency shifts for atomic clocks using a density-matrix formalism. The formalism is developed for both fermionic and bosonic atomic clocks. Numerical results for a finite-temperature {sup 87}Sr {sup 1}S{sub 0} (F=9/2) atomic clock in a magic wavelength optical lattice are presented.

  4. A probabilistic model for secondary structure prediction from protein chemical shifts.

    Science.gov (United States)

    Mechelke, Martin; Habeck, Michael

    2013-06-01

    Protein chemical shifts encode detailed structural information that is difficult and computationally costly to describe at a fundamental level. Statistical and machine learning approaches have been used to infer correlations between chemical shifts and secondary structure from experimental chemical shifts. These methods range from simple statistics such as the chemical shift index to complex methods using neural networks. Notwithstanding their higher accuracy, more complex approaches tend to obscure the relationship between secondary structure and chemical shift and often involve many parameters that need to be trained. We present hidden Markov models (HMMs) with Gaussian emission probabilities to model the dependence between protein chemical shifts and secondary structure. The continuous emission probabilities are modeled as conditional probabilities for a given amino acid and secondary structure type. Using these distributions as outputs of first- and second-order HMMs, we achieve a prediction accuracy of 82.3%, which is competitive with existing methods for predicting secondary structure from protein chemical shifts. Incorporation of sequence-based secondary structure prediction into our HMM improves the prediction accuracy to 84.0%. Our findings suggest that an HMM with correlated Gaussian distributions conditioned on the secondary structure provides an adequate generative model of chemical shifts.

  5. Bayesian inference of protein structure from chemical shift data

    DEFF Research Database (Denmark)

    Bratholm, Lars Andersen; Christensen, Anders Steen; Hamelryck, Thomas Wim;

    2015-01-01

    Monte Carlo simulations of three small proteins (ENHD, Protein G and the SMN Tudor Domain) using the PROFASI force field and the chemical shift predictor CamShift. Using a clustering-criterion for identifying the best structure, together with the addition of a solvent exposure scoring term...... content of the data. Here, we present the formulation of such a probability distribution where the error in chemical shift prediction is described by either a Gaussian or Cauchy distribution. The methodology is demonstrated and compared to a set of empirically weighted potentials through Markov chain......Protein chemical shifts are routinely used to augment molecular mechanics force fields in protein structure simulations, with weights of the chemical shift restraints determined empirically. These weights, however, might not be an optimal descriptor of a given protein structure and predictive model...

  6. A refined model of the chlorosomal antennae of the green bacterium chlorobium tepidum from proton chemical shift constraints obtained with high-field 2-D and 3-D MAS NMR dipolar correlation spectroscopy

    NARCIS (Netherlands)

    Rossum, van B.E.J.; Steengaard, D.B.; Boender, G.J.; Schaffner, K.; Holzwarth, A.R.; Groot, de H.J.M.

    2001-01-01

    Heteronuclear 2-D and 3-D magic-angle spinning NMR dipolar correlation spectroscopy was applied to determine solid-state 1H shifts for aggregated bacteriochlorophyll c (BChl c) in uniformly 13C-enriched light harvesting chlorosomes of the green photosynthetic bacterium Chlorobium tepidum. A complete

  7. Is the Lamb shift chemically significant?

    Science.gov (United States)

    Dyall, Kenneth G.; Bauschlicher, Charles W., Jr.; Schwenke, David W.; Pyykko, Pekka; Arnold, James (Technical Monitor)

    2001-01-01

    The contribution of the Lamb shift to the atomization energies of some prototype molecules, BF3, AlF3, and GaF3, is estimated by a perturbation procedure. It is found to be in the range of 3-5% of the one-electron scalar relativistic contribution to the atomization energy. The maximum absolute value is 0.2 kcal/mol for GaF3. These sample calculations indicate that the Lamb shift is probably small enough to be neglected for energetics of molecules containing light atoms if the target accuracy is 1 kcal/mol, but for higher accuracy calculations and for molecules containing heavy elements it must be considered.

  8. Improved chemical shift prediction by Rosetta conformational sampling

    Energy Technology Data Exchange (ETDEWEB)

    Tian Ye [Sanford Burnham Medical Research Institute (United States); Opella, Stanley J. [University of California San Diego, Department of Chemistry and Biochemistry (United States); Marassi, Francesca M., E-mail: fmarassi@sbmri.org [Sanford Burnham Medical Research Institute (United States)

    2012-11-15

    Chemical shift frequencies represent a time-average of all the conformational states populated by a protein. Thus, chemical shift prediction programs based on sequence and database analysis yield higher accuracy for rigid rather than flexible protein segments. Here we show that the prediction accuracy can be significantly improved by averaging over an ensemble of structures, predicted solely from amino acid sequence with the Rosetta program. This approach to chemical shift and structure prediction has the potential to be useful for guiding resonance assignments, especially in solid-state NMR structural studies of membrane proteins in proteoliposomes.

  9. Effects of structural differences on the NMR chemical shifts in isostructural dipeptides.

    Science.gov (United States)

    Altheimer, Benjamin D; Mehta, Manish A

    2014-04-10

    Porous crystalline dipeptides have gained recent attention for their potential as gas-storage materials. Within this large class is a group of dipeptides containing alanine, valine, and isoleucine with very similar crystal structures. We report the (13)C (carbonyl and Cα) and (15)N (amine and amide) solid-state NMR isotropic chemical shifts in a series of seven such isostructural porous dipeptides as well as shift tensor data for the carbonyl and amide sites. Using their known crystal structures and aided by ab initio quantum chemical calculations for the resonance assignments, we elucidate trends relating local structure, hydrogen-bonding patterns, and chemical shift. We find good correlation between the backbone dihedral angles and the Cα1 and Cα2 shifts. For the C1 shift tensor, the δ11 value shifts downfield as the hydrogen-bond distance increases, δ22 shifts upfield, and δ33 shows little variation. The C2 shift tensor shows no appreciable correlation with structural parameters. For the N2 tensor, δ11 shows little dependence on the hydrogen-bond length, whereas δ22 and δ33 both show a decrease in shielding as the hydrogen bond shortens. Our analysis teases apart some, but not all, structural contributors to the observed differences the solid-state NMR chemical shifts.

  10. Calculations of proton chemical shifts in olefins and aromatics

    CERN Document Server

    Escrihuela, M C

    2000-01-01

    induced reagents on alpha,beta unsaturated ketones has also been investigated in order to deduce molecular structures and to obtain the assignment of the spectra of these molecules. A semi-empirical calculation of the partial atomic charges in organic compounds based on molecular dipole moments (CHARGE3) was developed into a model capable of predicting proton chemical shifts in a wide variety of organic compounds to a reasonable degree of accuracy. The model has been modified to include condensed aromatic hydrocarbons and substituted benzenes, alkenes, halo-monosubstituted benzenes and halo-alkenes. Within the aromatic compounds the influence of the pi electron densities and the ring current have been investigated, along with the alpha, beta and gamma effects. The model gives the first accurate calculation of the proton chemical shifts of condensed aromatic compounds and the proton substituent chemical shifts (SCS) in the benzene ring. For the data set of 55 proton chemical shifts spanning 3 ppm the rms error...

  11. Nearly optimal correlations for shift-invariant associative memories.

    Science.gov (United States)

    Khoury, J; Gianino, P D; Woods, C L

    1995-07-10

    The optical implementation of the Hopfield algorithm in shift-invariant holographic associative memories is based on the use of correlators with matched filters. However, it is well known that such correlators have poor discrimination. We propose nearly optimal correlation designs for associative memories based on correlation filters that have maximum discrimination ability. These new designs avoid large cross-correlation-peak terms caused by a mismatch between partial input and the fully stored information in the filter. These solutions rely on whitened spectra of the stored and the recalled information.Computer simulations are made of eight different combinations.

  12. Proton chemical shift tensors determined by 3D ultrafast MAS double-quantum NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Rongchun; Mroue, Kamal H.; Ramamoorthy, Ayyalusamy, E-mail: ramamoor@umich.edu [Biophysics and Department of Chemistry, The University of Michigan, Ann Arbor, Michigan 48109-1055 (United States)

    2015-10-14

    Proton NMR spectroscopy in the solid state has recently attracted much attention owing to the significant enhancement in spectral resolution afforded by the remarkable advances in ultrafast magic angle spinning (MAS) capabilities. In particular, proton chemical shift anisotropy (CSA) has become an important tool for obtaining specific insights into inter/intra-molecular hydrogen bonding. However, even at the highest currently feasible spinning frequencies (110–120 kHz), {sup 1}H MAS NMR spectra of rigid solids still suffer from poor resolution and severe peak overlap caused by the strong {sup 1}H–{sup 1}H homonuclear dipolar couplings and narrow {sup 1}H chemical shift (CS) ranges, which render it difficult to determine the CSA of specific proton sites in the standard CSA/single-quantum (SQ) chemical shift correlation experiment. Herein, we propose a three-dimensional (3D) {sup 1}H double-quantum (DQ) chemical shift/CSA/SQ chemical shift correlation experiment to extract the CS tensors of proton sites whose signals are not well resolved along the single-quantum chemical shift dimension. As extracted from the 3D spectrum, the F1/F3 (DQ/SQ) projection provides valuable information about {sup 1}H–{sup 1}H proximities, which might also reveal the hydrogen-bonding connectivities. In addition, the F2/F3 (CSA/SQ) correlation spectrum, which is similar to the regular 2D CSA/SQ correlation experiment, yields chemical shift anisotropic line shapes at different isotropic chemical shifts. More importantly, since the F2/F1 (CSA/DQ) spectrum correlates the CSA with the DQ signal induced by two neighboring proton sites, the CSA spectrum sliced at a specific DQ chemical shift position contains the CSA information of two neighboring spins indicated by the DQ chemical shift. If these two spins have different CS tensors, both tensors can be extracted by numerical fitting. We believe that this robust and elegant single-channel proton-based 3D experiment provides useful atomistic

  13. Bayesian inference of protein structure from chemical shift data

    DEFF Research Database (Denmark)

    Bratholm, Lars Andersen; Christensen, Anders Steen; Hamelryck, Thomas Wim;

    2015-01-01

    Protein chemical shifts are routinely used to augment molecular mechanics force fields in protein structure simulations, with weights of the chemical shift restraints determined empirically. These weights, however, might not be an optimal descriptor of a given protein structure and predictive model...... Monte Carlo simulations of three small proteins (ENHD, Protein G and the SMN Tudor Domain) using the PROFASI force field and the chemical shift predictor CamShift. Using a clustering-criterion for identifying the best structure, together with the addition of a solvent exposure scoring term......, result in overall better convergence to the native fold, suggesting that both types of distribution might be useful in different aspects of the protein structure prediction....

  14. Counterion influence on chemical shifts in strychnine salts

    Energy Technology Data Exchange (ETDEWEB)

    Metaxas, Athena E.; Cort, John R.

    2013-05-01

    The highly toxic plant alkaloid strychnine is often isolated in the form of the anion salt of its protonated tertiary amine. Here we characterize the relative influence of different counterions on 1H and 13C chemical shifts in several strychnine salts in D2O, methanol-d4 (CD3OD) and chloroform-d (CDCl3) solvents. In organic solvents, but not in water, substantial variation in chemical shifts of protons near the tertiary amine was observed among different salts. These secondary shifts reveal differences in the way each anion influences electronic structure within the protonated amine. The distributions of secondary shifts allow salts to be easily distinguished from each other as well as from the free base form. The observed effects are much greater in organic solvents than in water. Slight concentration-dependence in chemical shifts of some protons near the amine was observed for two salts in CDCl3, but this effect is small compared to the influence of the counterion. Distinct chemical shifts in different salt forms of the same compound may be useful as chemical forensic signatures for source attribution and sample matching of alkaloids such as strychnine and possibly other organic acid and base salts.

  15. Theoretical Modeling of 99 Tc NMR Chemical Shifts

    Energy Technology Data Exchange (ETDEWEB)

    Hall, Gabriel B.; Andersen, Amity; Washton, Nancy M.; Chatterjee, Sayandev; Levitskaia, Tatiana G.

    2016-09-06

    Technetium (Tc) displays a rich chemistry due to the wide range of oxidation states (from -I to +VII) and ability to form coordination compounds. Determination of Tc speciation in complex mixtures is a major challenge, and 99Tc NMR spec-troscopy is widely used to probe chemical environments of Tc in odd oxidation states. However interpretation of the 99Tc NMR data is hindered by the lack of reference compounds. DFT computations can help fill this gap, but to date few com-putational studies have focused on 99Tc NMR of compounds and complexes. This work systematically evaluates the inclu-sion small percentages of Hartree-Fock exchange correlation and relativistic effects in DFT computations to support in-terpretation of the 99Tc NMR spectra. Hybrid functionals are found to perform better than their pure GGA counterparts, and non-relativistic calculations have been found to generally show a lower mean absolute deviation from experiment. Overall non-relativistic PBE0 and B3PW91 calculations are found to most accurately predict 99Tc NMR chemical shifts.

  16. /sup 3/H-/sup 1/H shift correlation NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Funke, C.W.; Wagenaars, G.N.; Kaspersen, F.M.

    1986-05-01

    Three two-dimensional /sup 3/H-/sup 1/H chemical shift correlation experiments are described, all using familiar pulse sequences. The experiments reveal the chemical shifts of the /sup 1/H spins which are coupled scalarly to a /sup 3/H spin and, thus, assist in the unambiguous location of this /sup 3/H spin within the molecule. The limitations for molecules involving a /sup 3/H spin which is coupled differently to various /sup 1/H spins are indicated. In practice, the detection limit is of the order of 100 MBq per /sup 3/H-labelling site.

  17. Conformationally selective multidimensional chemical shift ranges in proteins from a PACSY database purged using intrinsic quality criteria

    OpenAIRE

    2015-01-01

    We have determined refined multidimensional chemical shift ranges for intra-residue correlations ([superscript 13]C–[superscript 13]C, [superscript 15]N–[superscript 13]C, etc.) in proteins, which can be used to gain type-assignment and/or secondary-structure information from experimental NMR spectra. The chemical-shift ranges are the result of a statistical analysis of the PACSY database of >3000 proteins with 3D structures (1,200,207 [superscript 13]C chemical shifts and >3 million chemical...

  18. From NMR chemical shifts to amino acid types: Investigation of the predictive power carried by nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Marin, Antoine; Malliavin, Therese E. [Institut de Biologie Physico-Chimique, Laboratoire de Biochimie Theorique, CNRS UPR 9080 (France)], E-mail: therese.malliavin@ibpc.fr; Nicolas, Pierre; Delsuc, Marc-Andre [INRA - Domaine de Vilvert, Unite Mathematique Informatique et Genome (France)

    2004-09-15

    An approach to automatic prediction of the amino acid type from NMR chemical shift values of its nuclei is presented here, in the frame of a model to calculate the probability of an amino acid type given the set of chemical shifts. The method relies on systematic use of all chemical shift values contained in the BioMagResBank (BMRB). Two programs were designed, one (BMRB stats) for extracting statistical chemical shift parameters from the BMRB and another one (RESCUE2) for computing the probabilities of each amino acid type, given a set of chemical shifts. The Bayesian prediction scheme presented here is compared to other methods already proposed: PROTYP (Grzesiek and Bax, J. Biomol. NMR, 3, 185-204, 1993) RESCUE (Pons and Delsuc, J. Biomol. NMR, 15, 15-26, 1999) and PLATON (Labudde et al., J. Biomol. NMR, 25, 41-53, 2003) and is found to be more sensitive and more specific. Using this scheme, we tested various sets of nuclei. The two nuclei carrying the most information are C{sub {beta}} and H{sub {beta}}, in agreement with observations made in Grzesiek and Bax, 1993. Based on four nuclei: H{sub {beta}}, C{sub {beta}}, C{sub {alpha}} and C', it is possible to increase correct predictions to a rate of more than 75%. Taking into account the correlations between the nuclei chemical shifts has only a slight impact on the percentage of correct predictions: indeed, the largest correlation coefficients display similar features on all amino acids.

  19. Improving 3D structure prediction from chemical shift data

    Energy Technology Data Exchange (ETDEWEB)

    Schot, Gijs van der [Utrecht University, Computational Structural Biology, Bijvoet Center for Biomolecular Research, Faculty of Science-Chemistry (Netherlands); Zhang, Zaiyong [Technische Universitaet Muenchen, Biomolecular NMR and Munich Center for Integrated Protein Science, Department Chemie (Germany); Vernon, Robert [University of Washington, Department of Biochemistry (United States); Shen, Yang [National Institutes of Health, Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases (United States); Vranken, Wim F. [VIB, Department of Structural Biology (Belgium); Baker, David [University of Washington, Department of Biochemistry (United States); Bonvin, Alexandre M. J. J., E-mail: a.m.j.j.bonvin@uu.nl [Utrecht University, Computational Structural Biology, Bijvoet Center for Biomolecular Research, Faculty of Science-Chemistry (Netherlands); Lange, Oliver F., E-mail: oliver.lange@tum.de [Technische Universitaet Muenchen, Biomolecular NMR and Munich Center for Integrated Protein Science, Department Chemie (Germany)

    2013-09-15

    We report advances in the calculation of protein structures from chemical shift nuclear magnetic resonance data alone. Our previously developed method, CS-Rosetta, assembles structures from a library of short protein fragments picked from a large library of protein structures using chemical shifts and sequence information. Here we demonstrate that combination of a new and improved fragment picker and the iterative sampling algorithm RASREC yield significant improvements in convergence and accuracy. Moreover, we introduce improved criteria for assessing the accuracy of the models produced by the method. The method was tested on 39 proteins in the 50-100 residue size range and yields reliable structures in 70 % of the cases. All structures that passed the reliability filter were accurate (<2 A RMSD from the reference)

  20. Magnetic shift of the chemical freezeout and electric charge fluctuations

    CERN Document Server

    Fukushima, Kenji

    2016-01-01

    We discuss the effect of a strong magnetic field on the chemical freezeout points in the ultra-relativistic heavy-ion collision. As a result of the inverse magnetic catalysis or the magnetic inhibition, the crossover onset to hot and dense matter out of quarks and gluons should be shifted to a lower temperature. To quantify this shift we employ the hadron resonance gas model and an empirical condition for the chemical freezeout. We point out that the charged particle abundances are significantly affected by the magnetic field so that the electric charge fluctuation is largely enhanced especially at high baryon density. The charge conservation partially cancels the enhancement but our calculation shows that the electric charge fluctuation could serve as a magnetometer.

  1. Protein secondary structure prediction using NMR chemical shift data.

    Science.gov (United States)

    Zhao, Yuzhong; Alipanahi, Babak; Li, Shuai Cheng; Li, Ming

    2010-10-01

    Accurate determination of protein secondary structure from the chemical shift information is a key step for NMR tertiary structure determination. Relatively few work has been done on this subject. There needs to be a systematic investigation of algorithms that are (a) robust for large datasets; (b) easily extendable to (the dynamic) new databases; and (c) approaching to the limit of accuracy. We introduce new approaches using k-nearest neighbor algorithm to do the basic prediction and use the BCJR algorithm to smooth the predictions and combine different predictions from chemical shifts and based on sequence information only. Our new system, SUCCES, improves the accuracy of all existing methods on a large dataset of 805 proteins (at 86% Q(3) accuracy and at 92.6% accuracy when the boundary residues are ignored), and it is easily extendable to any new dataset without requiring any new training. The software is publicly available at http://monod.uwaterloo.ca/nmr/succes.

  2. Estimation of optical chemical shift in nuclear spin optical rotation

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Fang [Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Yao, Guo-hua [Key Laboratory of Ion Beam Bio-engineering, Institute of Technical Biology and Agriculture Engineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031 (China); He, Tian-jing [Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Chen, Dong-ming, E-mail: dmchen@ustc.edu.cn [Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Liu, Fan-chen, E-mail: fcliu@ustc.edu.cn [Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2014-05-19

    Highlights: • Analytical theory of nuclear spin optical rotation (NSOR) is further developed. • Derive formula of NSOR ratio R between different nuclei in a same molecule. • Calculated results of R agree with the experiments. • Analyze influence factors on R and chemical distinction by NSOR. - Abstract: A recently proposed optical chemical shift in nuclear spin optical rotation (NSOR) is studied by theoretical comparison of NSOR magnitude between chemically non-equivalent or different element nuclei in the same molecule. Theoretical expressions of the ratio R between their NSOR magnitudes are derived by using a known semi-empirical formula of NSOR. Taking methanol, tri-ethyl-phosphite and 2-methyl-benzothiazole as examples, the ratios R are calculated and the results approximately agree with the experiments. Based on those, the important influence factors on R and chemical distinction by NSOR are discussed.

  3. The correlation theory of the chemical bond

    CERN Document Server

    Szalay, Szilárd; Szilvási, Tibor; Veis, Libor; Legeza, Örs

    2016-01-01

    The notion of chemical bond is a very useful concept in chemistry. It originated at the beginning of chemistry, it is expressive for the classically thinking mind, and the errors arising from the approximative nature of the concept can often be ignored. In the first half of the twentieth century, however, we learned that the proper description of the microworld is given by quantum mechanics. Quantum mechanics gives more accurate results for chemical systems than any preceding model, however, it is very inexpressive for the classically thinking mind. The quantum mechanical description of the chemical bond is given in terms of delocalized bonding orbitals, or, alternatively, in terms of correlations of occupations of localized orbitals. However, in the latter case, multiorbital correlations were treated only in terms of two-orbital correlations, although the structure of multiorbital correlations is far richer; and, in the case of bonds established by more than two electrons, multiorbital correlations represent...

  4. Chemical shift assignments of two oleanane triterpenes from Euonymus hederaceus

    Institute of Scientific and Technical Information of China (English)

    HU He-jiao; WANG Kui-wu; WU Bin; SUN Cui-rong; PAN Yuan-jiang

    2005-01-01

    1H-NMR and 13C-NMR assignments of 12-oleanene-3,11-dione (compound 1) were completely described for the first time through conventional 1D NMR and 2D shift-correlated NMR experiments using 1H-1HCOSY, HMQC, HMBC techniques.Based on its NMR data, the assignments of 28-hydroxyolean-12-ene-3,11-dione (compound 2) were partially revised.

  5. Ontogenetic shift in response to prey-derived chemical cues in prairie rattlesnakes Crotalus viridis viridis

    Institute of Scientific and Technical Information of China (English)

    Anthony J.SAVIOLA; David CHISZAR; Stephen P.MACKESSY

    2012-01-01

    Snakes often have specialized diets that undergo a shift from one prey type to another depending on the life stage of the snake.Crotalus viridis viridis (prairie rattlesnake) takes different prey at different life stages,and neonates typically prey on ectotherms,while adults feed almost entirely on small endotherms.We hypothesized that elevated rates of tongue flicking to chemical stimuli should correlate with particular prey consumed,and that this response shifts from one prey type to another as individuals age.To examine if an ontogenetic shift in response to chemical cues occurred,we recorded the rate of tongue flicking for 25 neonate,20 subadult,and 20 adult (average SVL=280.9,552,789.5 mm,respectively) wild-caught C.v.viridis to chemical stimuli presented on a cotton-tipped applicator; water-soluble cues from two ectotherms (prairie lizard,Sceloporus undulatus,and house gecko,Hemidactylusfrenatus),two endotherms (deer mouse,Peromyscus maniculatus and lab mouse,Mus musculus),and water controls were used.Neonates tongue flicked significantly more to chemical cues of their common prey,S.undulatus,than to all other chemical cues; however,the response to this lizard's chemical cues decreased in adult rattlesnakes.Subadults tongue flicked with a higher rate of tongue flicking to both S.undulatus and P.maniculatus than to all other treatments,and adults tongue flicked significantly more to P.maniculatus than to all other chemical cues.In addition,all three sub-classes demonstrated a greater response for natural prey chemical cues over chemical stimuli of prey not encountered in the wild (M.musculus and H.frenatus).This shift in chemosensory response correlated with the previously described ontogenetic shifts in C.v.viridis diet.Because many vipers show a similar ontogenetic shift in diet and venom composition,we suggest that this shift in prey cue discrimination is likely a general phenomenon among viperid snakes.

  6. Relationship between electrophilicity index, Hammett constant and nucleus-independent chemical shift

    Indian Academy of Sciences (India)

    M Elango; R Parthasarathi; G Karthik Narayanan; A Md Sabeelullah; U Sarkar; N S Venkatasubramaniyan; V Subramanian; P K Chattaraj

    2005-01-01

    Inter-relationships between the electrophilicity index (), Hammett constant (ó) and nucleusindependent chemical shift (NICS (1) - NICS value one å ngstrom above the ring centre) have been investigated for a series of meta- and para-substituted benzoic acids. Good linear relationships between Hammett constant vs electrophilicity and Hammett constant vs NICS (1) values have been observed. However, the variation of NICS (1) against shows only a low correlation coefficient.

  7. Effects of source correlation on the spectral shift of light waves on scattering.

    Science.gov (United States)

    Wang, Tao; Zhao, Daomu

    2013-05-01

    The far-zone scattered spectrum has been investigated for the scattering of two correlated sources from a deterministic medium. It is shown that red shift or blue shift can be produced in the far-zone scattered spectrum, and the spectral shift is influenced by the source correlation.

  8. Conformationally selective multidimensional chemical shift ranges in proteins from a PACSY database purged using intrinsic quality criteria

    Energy Technology Data Exchange (ETDEWEB)

    Fritzsching, Keith J., E-mail: kfritzsc@brandeis.edu [Brandeis University, Department of Chemistry (United States); Hong, Mei [Massachusetts Institute of Technology, Department of Chemistry (United States); Schmidt-Rohr, Klaus, E-mail: srohr@brandeis.edu [Brandeis University, Department of Chemistry (United States)

    2016-02-15

    We have determined refined multidimensional chemical shift ranges for intra-residue correlations ({sup 13}C–{sup 13}C, {sup 15}N–{sup 13}C, etc.) in proteins, which can be used to gain type-assignment and/or secondary-structure information from experimental NMR spectra. The chemical-shift ranges are the result of a statistical analysis of the PACSY database of >3000 proteins with 3D structures (1,200,207 {sup 13}C chemical shifts and >3 million chemical shifts in total); these data were originally derived from the Biological Magnetic Resonance Data Bank. Using relatively simple non-parametric statistics to find peak maxima in the distributions of helix, sheet, coil and turn chemical shifts, and without the use of limited “hand-picked” data sets, we show that ∼94 % of the {sup 13}C NMR data and almost all {sup 15}N data are quite accurately referenced and assigned, with smaller standard deviations (0.2 and 0.8 ppm, respectively) than recognized previously. On the other hand, approximately 6 % of the {sup 13}C chemical shift data in the PACSY database are shown to be clearly misreferenced, mostly by ca. −2.4 ppm. The removal of the misreferenced data and other outliers by this purging by intrinsic quality criteria (PIQC) allows for reliable identification of secondary maxima in the two-dimensional chemical-shift distributions already pre-separated by secondary structure. We demonstrate that some of these correspond to specific regions in the Ramachandran plot, including left-handed helix dihedral angles, reflect unusual hydrogen bonding, or are due to the influence of a following proline residue. With appropriate smoothing, significantly more tightly defined chemical shift ranges are obtained for each amino acid type in the different secondary structures. These chemical shift ranges, which may be defined at any statistical threshold, can be used for amino-acid type assignment and secondary-structure analysis of chemical shifts from intra

  9. Conformationally selective multidimensional chemical shift ranges in proteins from a PACSY database purged using intrinsic quality criteria.

    Science.gov (United States)

    Fritzsching, Keith J; Hong, Mei; Schmidt-Rohr, Klaus

    2016-02-01

    We have determined refined multidimensional chemical shift ranges for intra-residue correlations ((13)C-(13)C, (15)N-(13)C, etc.) in proteins, which can be used to gain type-assignment and/or secondary-structure information from experimental NMR spectra. The chemical-shift ranges are the result of a statistical analysis of the PACSY database of >3000 proteins with 3D structures (1,200,207 (13)C chemical shifts and >3 million chemical shifts in total); these data were originally derived from the Biological Magnetic Resonance Data Bank. Using relatively simple non-parametric statistics to find peak maxima in the distributions of helix, sheet, coil and turn chemical shifts, and without the use of limited "hand-picked" data sets, we show that ~94% of the (13)C NMR data and almost all (15)N data are quite accurately referenced and assigned, with smaller standard deviations (0.2 and 0.8 ppm, respectively) than recognized previously. On the other hand, approximately 6% of the (13)C chemical shift data in the PACSY database are shown to be clearly misreferenced, mostly by ca. -2.4 ppm. The removal of the misreferenced data and other outliers by this purging by intrinsic quality criteria (PIQC) allows for reliable identification of secondary maxima in the two-dimensional chemical-shift distributions already pre-separated by secondary structure. We demonstrate that some of these correspond to specific regions in the Ramachandran plot, including left-handed helix dihedral angles, reflect unusual hydrogen bonding, or are due to the influence of a following proline residue. With appropriate smoothing, significantly more tightly defined chemical shift ranges are obtained for each amino acid type in the different secondary structures. These chemical shift ranges, which may be defined at any statistical threshold, can be used for amino-acid type assignment and secondary-structure analysis of chemical shifts from intra-residue cross peaks by inspection or by using a provided

  10. Applications of Chemical Shift Imaging to Marine Sciences

    Directory of Open Access Journals (Sweden)

    Haakil Lee

    2010-08-01

    Full Text Available The successful applications of magnetic resonance imaging (MRI in medicine are mostly due to the non-invasive and non-destructive nature of MRI techniques. Longitudinal studies of humans and animals are easily accomplished, taking advantage of the fact that MRI does not use harmful radiation that would be needed for plain film radiographic, computerized tomography (CT or positron emission (PET scans. Routine anatomic and functional studies using the strong signal from the most abundant magnetic nucleus, the proton, can also provide metabolic information when combined with in vivo magnetic resonance spectroscopy (MRS. MRS can be performed using either protons or hetero-nuclei (meaning any magnetic nuclei other than protons or 1H including carbon (13C or phosphorus (31P. In vivo MR spectra can be obtained from single region ofinterest (ROI or voxel or multiple ROIs simultaneously using the technique typically called chemical shift imaging (CSI. Here we report applications of CSI to marine samples and describe a technique to study in vivo glycine metabolism in oysters using 13C MRS 12 h after immersion in a sea water chamber dosed with [2-13C]-glycine. This is the first report of 13C CSI in a marine organism.

  11. Synthetic circular-harmonic phase-only filter for shift, rotation and scaling-invariant correlation

    DEFF Research Database (Denmark)

    Zi-Liang, ping; Dalsgaard, Erik

    1995-01-01

    A syntetic circuler-harmonic phase-only filter is described. With this filter and a Fourier-transform correlator it is possible to obtain shift, rotation and scaling-invariant correlations......A syntetic circuler-harmonic phase-only filter is described. With this filter and a Fourier-transform correlator it is possible to obtain shift, rotation and scaling-invariant correlations...

  12. Deuterium isotope effects on 13C chemical shifts of 10-Hydroxybenzo[h]quinolines

    DEFF Research Database (Denmark)

    Hansen, Poul Erik; Kamounah, Fadhil S.; Gryko, Daniel T.

    2013-01-01

    Deuterium isotope effects on 13C-NMR chemical shifts are investigated in a series of 10-hydroxybenzo[h]quinolines (HBQ’s) The OH proton is deuteriated. The isotope effects on 13C chemical shifts in these hydrogen bonded systems are rather unusual. The formal four-bond effects are found to be nega......Deuterium isotope effects on 13C-NMR chemical shifts are investigated in a series of 10-hydroxybenzo[h]quinolines (HBQ’s) The OH proton is deuteriated. The isotope effects on 13C chemical shifts in these hydrogen bonded systems are rather unusual. The formal four-bond effects are found...

  13. Optoelectronic Correlator Architecture for Shift Invariant Target Recognition

    CERN Document Server

    Monjur, Mehjabin S; Tripathi, Renu; Donoghue, John; Shahriar, M S

    2013-01-01

    In this paper, we present theoretical details and the underlying architecture of a hybrid optoelectronic correlator that correlates images using SLMs, detectors and VLSI chips. The proposed architecture bypasses the nonlinear material such as photorefractive polymer film by using detectors instead, and the phase information is yet conserved by the interference of plane waves with the images.

  14. Speech and neurology-chemical impairment correlates

    Science.gov (United States)

    Hayre, Harb S.

    2002-05-01

    Speech correlates of alcohol/drug impairment and its neurological basis is presented with suggestion for further research in impairment from poly drug/medicine/inhalent/chew use/abuse, and prediagnosis of many neuro- and endocrin-related disorders. Nerve cells all over the body detect chemical entry by smoking, injection, drinking, chewing, or skin absorption, and transmit neurosignals to their corresponding cerebral subsystems, which in turn affect speech centers-Broca's and Wernick's area, and motor cortex. For instance, gustatory cells in the mouth, cranial and spinal nerve cells in the skin, and cilia/olfactory neurons in the nose are the intake sensing nerve cells. Alcohol depression, and brain cell damage were detected from telephone speech using IMPAIRLYZER-TM, and the results of these studies were presented at 1996 ASA meeting in Indianapolis, and 2001 German Acoustical Society-DEGA conference in Hamburg, Germany respectively. Speech based chemical Impairment measure results were presented at the 2001 meeting of ASA in Chicago. New data on neurotolerance based chemical impairment for alcohol, drugs, and medicine shall be presented, and shown not to fully support NIDA-SAMSHA drug and alcohol threshold used in drug testing domain.

  15. Subpixel Accuracy Analysis of Phase Correlation Shift Measurement Methods Applied to Satellite Imagery

    Directory of Open Access Journals (Sweden)

    S.M. Badwai

    2013-01-01

    Full Text Available the key point of super resolution process is the accurate measuring of sub-pixel shift. Any tiny error in measuring such shift leads to an incorrect image focusing. In this paper, methodology of measuring sub-pixel shift using Phase correlation (PC are evaluated using different window functions, then modified version of (PC method using high pass filter (HPF is introduced . Comprehensive analysis and assessment of (PC methods shows that different natural features yield different shift measurements. It is concluded that there is no universal window function for measuring shift; it mainly depends on the features in the satellite images. Even the question of which window is optimal of particular feature is generally remains open. This paper presents the design of a method for obtaining high accuracy sub pixel shift phase correlation using (HPF.The proposed method makes the change in the different locations that lack of edges easy.

  16. Inferential protein structure determination and refinement using fast, electronic structure based backbone amide chemical shift predictions

    CERN Document Server

    Christensen, Anders S

    2015-01-01

    This report covers the development of a new, fast method for calculating the backbone amide proton chemical shifts in proteins. Through quantum chemical calculations, structure-based forudsiglese the chemical shift for amidprotonen in protein has been parameterized. The parameters are then implemented in a computer program called Padawan. The program has since been implemented in protein folding program Phaistos, wherein the method andvendes to de novo folding of the protein structures and to refine the existing protein structures.

  17. Ab Initio Calculation of Nuclear Magnetic Resonance Chemical Shift Anisotropy Tensors 1. Influence of Basis Set on the Calculation of 31P Chemical Shifts

    Energy Technology Data Exchange (ETDEWEB)

    Alam, T.M.

    1998-09-01

    The influence of changes in the contracted Gaussian basis set used for ab initio calculations of nuclear magnetic resonance (NMR) phosphorous chemical shift anisotropy (CSA) tensors was investigated. The isotropic chemical shitl and chemical shift anisotropy were found to converge with increasing complexity of the basis set at the Hartree-Fock @IF) level. The addition of d polarization function on the phosphorous nucIei was found to have a major impact of the calculated chemical shi~ but diminished with increasing number of polarization fimctions. At least 2 d polarization fimctions are required for accurate calculations of the isotropic phosphorous chemical shift. The introduction of density fictional theory (DFT) techniques through tie use of hybrid B3LYP methods for the calculation of the phosphorous chemical shift tensor resulted in a poorer estimation of the NMR values, even though DFT techniques result in improved energy and force constant calculations. The convergence of the W parametem with increasing basis set complexity was also observed for the DFT calculations, but produced results with consistent large deviations from experiment. The use of a HF 6-31 l++G(242p) basis set represents a good compromise between accuracy of the simulation and the complexity of the calculation for future ab initio calculations of 31P NMR parameters in larger complexes.

  18. DFT calculations of 1H and 13C NMR chemical shifts in transition metal hydrides.

    Science.gov (United States)

    del Rosal, I; Maron, L; Poteau, R; Jolibois, F

    2008-08-14

    instance in cluster chemistry. The reliance of NMR chemical shielding on dynamical effects, such as intramolecular rearrangements or trigonal twists, is also examined for H2Fe(CO)4, K+[HFe(CO)](-), HMn(CO)5 and HRe(CO)5. The accuracy of the theory is also examined for complexes with two dihydrogen ligands (Tp*RuH(H2)2 and [FeH(H2)(DMPE)2]+) and a ruthenium cluster, [H3Ru4(C6H6)4(CO)]+. It is shown that for all complexes studied in this work, the effect of the ligands on the chemical shielding of hydrogen coordinated to metal is suitably calculated, thus yielding a very good correlation between experimental chemical shifts and theoretical chemical shielding.

  19. Origin of the conformational modulation of the 13C NMR chemical shift of methoxy groups in aromatic natural compounds.

    Science.gov (United States)

    Toušek, Jaromír; Straka, Michal; Sklenář, Vladimír; Marek, Radek

    2013-01-24

    The interpretation of nuclear magnetic resonance (NMR) parameters is essential to understanding experimental observations at the molecular and supramolecular levels and to designing new and more efficient molecular probes. In many aromatic natural compounds, unusual (13)C NMR chemical shifts have been reported for out-of-plane methoxy groups bonded to the aromatic ring (~62 ppm as compared to the typical value of ~56 ppm for an aromatic methoxy group). Here, we analyzed this phenomenon for a series of aromatic natural compounds using Density Functional Theory (DFT) calculations. First, we checked the methodology used to optimize the structure and calculate the NMR chemical shifts in aromatic compounds. The conformational effects of the methoxy group on the (13)C NMR chemical shift then were interpreted by the Natural Bond Orbital (NBO) and Natural Chemical Shift (NCS) approaches, and by excitation analysis of the chemical shifts, breaking down the total nuclear shielding tensor into the contributions from the different occupied orbitals and their magnetic interactions with virtual orbitals. We discovered that the atypical (13)C NMR chemical shifts observed are not directly related to a different conjugation of the lone pair of electrons of the methoxy oxygen with the aromatic ring, as has been suggested. Our analysis indicates that rotation of the methoxy group induces changes in the virtual molecular orbital space, which, in turn, correlate with the predominant part of the contribution of the paramagnetic deshielding connected with the magnetic interactions of the BD(CMet-H)→BD*(CMet-OMet) orbitals, resulting in the experimentally observed deshielding of the (13)C NMR resonance of the out-of-plane methoxy group.

  20. A robust algorithm for optimizing protein structures with NMR chemical shifts.

    Science.gov (United States)

    Berjanskii, Mark; Arndt, David; Liang, Yongjie; Wishart, David S

    2015-11-01

    Over the past decade, a number of methods have been developed to determine the approximate structure of proteins using minimal NMR experimental information such as chemical shifts alone, sparse NOEs alone or a combination of comparative modeling data and chemical shifts. However, there have been relatively few methods that allow these approximate models to be substantively refined or improved using the available NMR chemical shift data. Here, we present a novel method, called Chemical Shift driven Genetic Algorithm for biased Molecular Dynamics (CS-GAMDy), for the robust optimization of protein structures using experimental NMR chemical shifts. The method incorporates knowledge-based scoring functions and structural information derived from NMR chemical shifts via a unique combination of multi-objective MD biasing, a genetic algorithm, and the widely used XPLOR molecular modelling language. Using this approach, we demonstrate that CS-GAMDy is able to refine and/or fold models that are as much as 10 Å (RMSD) away from the correct structure using only NMR chemical shift data. CS-GAMDy is also able to refine of a wide range of approximate or mildly erroneous protein structures to more closely match the known/correct structure and the known/correct chemical shifts. We believe CS-GAMDy will allow protein models generated by sparse restraint or chemical-shift-only methods to achieve sufficiently high quality to be considered fully refined and "PDB worthy". The CS-GAMDy algorithm is explained in detail and its performance is compared over a range of refinement scenarios with several commonly used protein structure refinement protocols. The program has been designed to be easily installed and easily used and is available at http://www.gamdy.ca.

  1. Protein structure validation and refinement using amide proton chemical shifts derived from quantum mechanics

    DEFF Research Database (Denmark)

    Christensen, Anders Steen; Linnet, Troels Emtekær; Borg, Mikael;

    2013-01-01

    We present the ProCS method for the rapid and accurate prediction of protein backbone amide proton chemical shifts - sensitive probes of the geometry of key hydrogen bonds that determine protein structure. ProCS is parameterized against quantum mechanical (QM) calculations and reproduces high level...... QM results obtained for a small protein with an RMSD of 0.25 ppm (r = 0.94). ProCS is interfaced with the PHAISTOS protein simulation program and is used to infer statistical protein ensembles that reflect experimentally measured amide proton chemical shift values. Such chemical shift...

  2. Chemical shift imaging and localised magnetic resonance spectroscopy in full-term asphyxiated neonates

    Energy Technology Data Exchange (ETDEWEB)

    Brissaud, Olivier [Children' s Hospital, Paediatric Intensive Care Unit, Bordeaux (France); Chateil, Jean-Francois; Bordessoules, Martine; Brun, Muriel [Children' s Hospital, Radiology Unit, Bordeaux (France)

    2005-10-01

    Diagnosis of brain lesions after birth anoxia-ischemia is essential for appropriate management. Clinical evaluation is not sufficient. MRI has been proven to provide useful information. To compare abnormalities observed with MRI, including diffusion-weighted imaging (DWI), localised magnetic resonance spectroscopy (MRS) and chemical shift imaging (CSI) and correlate these findings with the clinical outcome. Fourteen full-term neonates with birth asphyxia were studied. MRI, MRS and CSI were performed within the first 4 days of life. Lesions observed with DWI were correlated with outcome, but the apparent diffusion coefficient (ADC) did improve diagnostic confidence. The mean value of Lac/Cr for the neonates with a favourable outcome was statically lower than for those who died (0.22 vs 1.04; P = 0.01). The same results were observed for the Lac/NAA ratio (0.21 vs 1.23; P = 0.01). Data obtained with localised MRS and CSI were correlated for the ratio N-acetyl-aspartate/choline, but not for the other metabolites. No correlation was found between the ADC values and the metabolite ratios. Combination of these techniques could be helpful in our understanding of the physiopathological events occurring in neonates with asphyxia. (orig.)

  3. Observed and calculated 1H and 13C chemical shifts induced by the in situ oxidation of model sulfides to sulfoxides and sulfones.

    Science.gov (United States)

    Dracínský, Martin; Pohl, Radek; Slavetínská, Lenka; Budesínský, Milos

    2010-09-01

    A series of model sulfides was oxidized in the NMR sample tube to sulfoxides and sulfones by the stepwise addition of meta-chloroperbenzoic acid in deuterochloroform. Various methods of quantum chemical calculations have been tested to reproduce the observed (1)H and (13)C chemical shifts of the starting sulfides and their oxidation products. It has been shown that the determination of the energy-minimized conformation is a very important condition for obtaining realistic data in the subsequent calculation of the NMR chemical shifts. The correlation between calculated and observed chemical shifts is very good for carbon atoms (even for the 'cheap' DFT B3LYP/6-31G* method) and somewhat less satisfactory for hydrogen atoms. The calculated chemical shifts induced by oxidation (the Delta delta values) agree even better with the experimental values and can also be used to determine the oxidation state of the sulfur atom (-S-, -SO-, -SO(2)-).

  4. Deep sequencing analysis of HBV genotype shift and correlation with antiviral efficiency during adefovir dipivoxil therapy.

    Directory of Open Access Journals (Sweden)

    Yuwei Wang

    Full Text Available Viral genotype shift in chronic hepatitis B (CHB patients during antiviral therapy has been reported, but the underlying mechanism remains elusive.38 CHB patients treated with ADV for one year were selected for studying genotype shift by both deep sequencing and Sanger sequencing method.Sanger sequencing method found that 7.9% patients showed mixed genotype before ADV therapy. In contrast, all 38 patients showed mixed genotype before ADV treatment by deep sequencing. 95.5% mixed genotype rate was also obtained from additional 200 treatment-naïve CHB patients. Of the 13 patients with genotype shift, the fraction of the minor genotype in 5 patients (38% increased gradually during the course of ADV treatment. Furthermore, responses to ADV and HBeAg seroconversion were associated with the high rate of genotype shift, suggesting drug and immune pressure may be key factors to induce genotype shift. Interestingly, patients with genotype C had a significantly higher rate of genotype shift than genotype B. In genotype shift group, ADV treatment induced a marked enhancement of genotype B ratio accompanied by a reduction of genotype C ratio, suggesting genotype C may be more sensitive to ADV than genotype B. Moreover, patients with dominant genotype C may have a better therapeutic effect. Finally, genotype shifts was correlated with clinical improvement in terms of ALT.Our findings provided a rational explanation for genotype shift among ADV-treated CHB patients. The genotype and genotype shift might be associated with antiviral efficiency.

  5. On the relation between the echo-peak shift and Brownian-oscillator correlation function

    NARCIS (Netherlands)

    de Boeij, W.P.; Pshenichnikov, M.S; Wiersma, D. A.

    1996-01-01

    We show that for systems that exhibit bimodal dynamics in their system-bath correlation function the shift of the stimulated photon-echo maximum as a function of waiting time reflects fairly well the long time part of the correlation function. For early times this correspondence breaks down due to a

  6. PPM-One: a static protein structure based chemical shift predictor

    Energy Technology Data Exchange (ETDEWEB)

    Li, Dawei; Brüschweiler, Rafael, E-mail: bruschweiler.1@osu.edu [The Ohio State University, Campus Chemical Instrument Center (United States)

    2015-07-15

    We mined the most recent editions of the BioMagResDataBank and the protein data bank to parametrize a new empirical knowledge-based chemical shift predictor of protein backbone atoms using either a linear or an artificial neural network model. The resulting chemical shift predictor PPM-One accepts a single static 3D structure as input and emulates the effect of local protein dynamics via interatomic steric contacts. Furthermore, the chemical shift prediction was extended to most side-chain protons and it is found that the prediction accuracy is at a level allowing an independent assessment of stereospecific assignments. For a previously established set of test proteins some overall improvement was achieved over current top-performing chemical shift prediction programs.

  7. Phase-shifting technique applied to circular harmonic-based joint transform correlator

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The phase-shifting technique is applied to the circular harmonic expansion-based joint transform correlator. Computer simulation has shown that the light efficiency and the discrimination capability are greatly enhanced, and the full rotation invariance is preserved after the phase-shifting technique has been used. A rotation-invariant optical pattern recognition with high discrimination capability and high light efficiency is obtained. The influence of the additive noise on the performance of the correlator is also investigated. However, the anti-noise capability of this kind of correlator still needs improving.

  8. Prediction of hydrogen and carbon chemical shifts from RNA using database mining and support vector regression

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Joshua D.; Summers, Michael F. [University of Maryland Baltimore County, Howard Hughes Medical Institute (United States); Johnson, Bruce A., E-mail: bruce.johnson@asrc.cuny.edu [University of Maryland Baltimore County, Department of Chemistry and Biochemistry (United States)

    2015-09-15

    The Biological Magnetic Resonance Data Bank (BMRB) contains NMR chemical shift depositions for over 200 RNAs and RNA-containing complexes. We have analyzed the {sup 1}H NMR and {sup 13}C chemical shifts reported for non-exchangeable protons of 187 of these RNAs. Software was developed that downloads BMRB datasets and corresponding PDB structure files, and then generates residue-specific attributes based on the calculated secondary structure. Attributes represent properties present in each sequential stretch of five adjacent residues and include variables such as nucleotide type, base-pair presence and type, and tetraloop types. Attributes and {sup 1}H and {sup 13}C NMR chemical shifts of the central nucleotide are then used as input to train a predictive model using support vector regression. These models can then be used to predict shifts for new sequences. The new software tools, available as stand-alone scripts or integrated into the NMR visualization and analysis program NMRViewJ, should facilitate NMR assignment and/or validation of RNA {sup 1}H and {sup 13}C chemical shifts. In addition, our findings enabled the re-calibration a ring-current shift model using published NMR chemical shifts and high-resolution X-ray structural data as guides.

  9. Chemical shift selective magnetic resonance imaging of the optic nerve in patients with acute optic neuritis

    DEFF Research Database (Denmark)

    Larsson, H B; Thomsen, C; Frederiksen, J;

    1988-01-01

    Optic neuritis is often the first manifestation of multiple sclerosis (MS). Sixteen patients with acute optic neuritis and one patient with benign intracranial hypertension (BIH) were investigated by magnetic resonance imaging, using a chemical shift selective double spin echo sequence. In 3...... were only shown in 3/16 (19%) of the patients with optic neuritis. Nevertheless, the presented chemical shift selective double spin echo sequence may be of great value for detection of retrobulbar lesions....

  10. Chemical shift MRI can aid in the diagnosis of indeterminate skeletal lesions of the spine

    Energy Technology Data Exchange (ETDEWEB)

    Douis, H. [University Hospital Birmingham, Department of Radiology, Birmingham (United Kingdom); Royal Orthopaedic Hospital, Department of Radiology, Birmingham (United Kingdom); Davies, A.M. [Royal Orthopaedic Hospital, Department of Radiology, Birmingham (United Kingdom); Jeys, L. [Royal Orthopaedic Hospital, Department of Orthopaedic Oncology, Birmingham (United Kingdom); Sian, P. [Royal Orthopaedic Hospital, Department of Spinal Surgery and Spinal Oncology, Birmingham (United Kingdom)

    2016-04-15

    To evaluate the role of chemical shift MRI in the characterisation of indeterminate skeletal lesions of the spine as benign or malignant. Fifty-five patients (mean age 54.7 years) with 57 indeterminate skeletal lesions of the spine were included in this retrospective study. In addition to conventional MRI at 3 T which included at least sagittal T1WI and T2WI/STIR sequences, patients underwent chemical shift MRI. A cut-off value with a signal drop-out of 20 % was used to differentiate benign lesions from malignant lesions (signal drop-out <20 % being malignant). There were 45 benign lesions and 12 malignant lesions. Chemical shift imaging correctly diagnosed 33 of 45 lesions as benign and 11 of 12 lesions as malignant. In contrast, there were 12 false positive cases and 1 false negative case based on chemical shift MRI. This yielded a sensitivity of 91.7 %, a specificity of 73.3 %, a negative predictive value of 97.1 %, a positive predictive value of 47.8 % and a diagnostic accuracy of 82.5 %. Chemical shift MRI can aid in the characterisation of indeterminate skeletal lesions of the spine in view of its high sensitivity in diagnosing malignant lesions. Chemical shift MRI can potentially avoid biopsy in a considerable percentage of patients with benign skeletal lesions of the spine. (orig.)

  11. Effects of side-chain orientation on the {sup 13}C chemical shifts of antiparallel {beta}-sheet model peptides

    Energy Technology Data Exchange (ETDEWEB)

    Villegas, Myriam E.; Vila, Jorge A. [Facultad de Ciencias Fisico Matematicas y Naturales, Instituto de Matematica Aplicada San Luis, Universidad Nacional de San Luis, CONICET (Argentina); Scheraga, Harold A. [Cornell University, Baker Laboratory of Chemistry and Chemical Biology (United States)], E-mail: has5@cornell.edu

    2007-02-15

    The dependence of the {sup 13}C chemical shift on side-chain orientation was investigated at the density functional level for a two-strand antiparallel {beta}-sheet model peptide represented by the amino acid sequence Ac-(Ala){sub 3}-X-(Ala){sub 12}-NH{sub 2} where X represents any of the 17 naturally occurring amino acids, i.e., not including alanine, glycine and proline. The dihedral angles adopted for the backbone were taken from, and fixed at, observed experimental values of an antiparallel {beta}-sheet. We carried out a cluster analysis of the ensembles of conformations generated by considering the side-chain dihedral angles for each residue X as variables, and use them to compute the {sup 13}C chemical shifts at the density functional theory level. It is shown that the adoption of the locally-dense basis set approach for the quantum chemical calculations enabled us to reduce the length of the chemical-shift calculations while maintaining good accuracy of the results. For the 17 naturally occurring amino acids in an antiparallel {beta}-sheet, there is (i) good agreement between computed and observed {sup 13}C{sup {alpha}} and {sup 13}C{sup {beta}} chemical shifts, with correlation coefficients of 0.95 and 0.99, respectively; (ii) significant variability of the computed {sup 13}C{sup {alpha}} and {sup 13}C{sup {beta}} chemical shifts as a function of {chi}{sup 1} for all amino acid residues except Ser; and (iii) a smaller, although significant, dependence of the computed {sup 13}C{sup {alpha}} chemical shifts on {chi}{sup {xi}} (with {xi} {>=} 2) compared to {chi}{sup 1} for eleven out of seventeen residues. Our results suggest that predicted {sup 13}C{sup {alpha}} and {sup 13}C{sup {beta}} chemical shifts, based only on backbone ({phi},{psi}) dihedral angles from high-resolution X-ray structure data or from NMR-derived models, may differ significantly from those observed in solution if the dihedral-angle preferences for the side chains are not taken into

  12. Core correlation effects in multiconfiguration calculations of isotope shifts in Mg I

    CERN Document Server

    Filippin, Livio; Ekman, Jörgen; Jönsson, Per

    2016-01-01

    The present work reports results from systematic multiconfiguration Dirac-Hartree-Fock calculations of isotope shifts for several well-known transitions in neutral magnesium. Relativistic normal and specific mass shift factors as well as the electronic probability density at the origin are calculated. Combining these electronic quantities with available nuclear data, energy and transition level shifts are determined for the $^{26}$Mg$-^{24}$Mg pair of isotopes. Different models for electron correlation are adopted. It is shown that although valence and core-valence models provide accurate values for the isotope shifts, the inclusion of core-core excitations in the computational strategy significantly improves the accuracy of the transition energies and normal mass shift factors.

  13. Further conventions for NMR shielding and chemical shifts (IUPAC Recommendations 2008)

    Energy Technology Data Exchange (ETDEWEB)

    Harris, R.K. [University of Durham, Durham (United Kingdom). Dept. of Chemistry; Becker, E.D. [National Institutes of Health, Bethesda, MD (United States); Menezes, S.M. Cabral de [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES); Granger, P. [University Louis Pasteur, Strasbourg (France). Inst. of Chemistry; Hoffman, R.E. [The Hebrew University of Jerusalem, Safra Campus, Jerusalem (Israel). Dept. of Organic Chemistry; Zilm, K.W., E-mail: r.k.harris@durham.ac.uk [Yale University, New Haven, CT (United States). Dept. of Chemistry

    2008-07-01

    IUPAC has published a number of recommendations regarding the reporting of nuclear magnetic resonance (NMR) data, especially chemical shifts. The most recent publication [Pure Appl. Chem. 73, 1795 (2001)] recommended that tetramethylsilane (TMS) serve as a universal reference for reporting the shifts of all nuclides, but it deferred recommendations for several aspects of this subject. This document first examines the extent to which the {sup 1}H shielding in TMS itself is subject to change by variation in temperature, concentration, and solvent. On the basis of recently published results, it has been established that the shielding of TMS in solution [along with that of sodium-3- (trimethylsilyl)propanesulfonate, DSS, often used as a reference for aqueous solutions] varies only slightly with temperature but is subject to solvent perturbations of a few tenths of a part per million (ppm). Recommendations are given for reporting chemical shifts under most routine experimental conditions and for quantifying effects of temperature and solvent variation, including the use of magnetic susceptibility corrections and of magic-angle spinning (MAS). This document provides the first IUPAC recommendations for referencing and reporting chemical shifts in solids, based on high-resolution MAS studies. Procedures are given for relating {sup 13}C NMR chemical shifts in solids to the scales used for high resolution studies in the liquid phase. The notation and terminology used for describing chemical shift and shielding tensors in solids are reviewed in some detail, and recommendations are given for best practice. (author)

  14. Magnetic couplings in the chemical shift of paramagnetic NMR.

    Science.gov (United States)

    Vaara, Juha; Rouf, Syed Awais; Mareš, Jiří

    2015-10-13

    We apply the Kurland-McGarvey (J. Magn. Reson. 1970, 2, 286) theory for the NMR shielding of paramagnetic molecules, particularly its special case limited to the ground-state multiplet characterized by zero-field splitting (ZFS) interaction of the form S·D·S. The correct formulation for this problem was recently presented by Soncini and Van den Heuvel (J. Chem. Phys. 2013, 138, 054113). With the effective electron spin quantum number S, the theory involves 2S+1 states, of which all but one are low-lying excited states, between which magnetic couplings take place by Zeeman and hyperfine interactions. We investigate these couplings as a function of temperature, focusing on both the high- and low-temperature behaviors. As has been seen in work by others, the full treatment of magnetic couplings is crucial for a realistic description of the temperature behavior of NMR shielding up to normal measurement temperatures. At high temperatures, depending on the magnitude of ZFS, the effect of magnetic couplings diminishes, and the Zeeman and hyperfine interactions become effectively averaged in the thermally occupied states of the multiplet. At still higher temperatures, the ZFS may be omitted altogether, and the shielding properties may be evaluated using a doublet-like formula, with all the 2S+1 states becoming effectively degenerate at the limit of vanishing magnetic field. We demonstrate these features using first-principles calculations of Ni(II), Co(II), Cr(II), and Cr(III) complexes, which have ZFS of different sizes and signs. A non-monotonic inverse temperature dependence of the hyperfine shift is predicted for axially symmetric integer-spin systems with a positive D parameter of ZFS. This is due to the magnetic coupling terms that are proportional to kT at low temperatures, canceling the Curie-type 1/kT prefactor of the hyperfine shielding in this case.

  15. Effect of shifting cultivation on soil physical and chemical properties in Bandarban hill district, Bangladesh

    Institute of Scientific and Technical Information of China (English)

    Khandakar Showkat Osman; M. Jashimuddin; S. M. Sirajul Haque; Sohag Miah

    2013-01-01

    This study reports the effects of shifting cultivation at slashing stage on soil physicochemical properties at Bandarban Sadar Upazila in Chittagong Hill Tracts of Bangladesh. At this initial stage of shifting cultivation no general trend was found for moisture content, maximum water holding capacity, field capacity, dry and moist bulk density, parti-cle density for some chemical properties between shifting cultivated land and forest having similar soil texture. Organic matter was significantly (p≤0.05) lower in 1-year and 3-year shifting cultivated lands and higher in 2-year shifting cultivation than in adjacent natural forest. Significant differences were also found for total N, exchangeable Ca, Mg and K and in CEC as well as for available P. Slashed area showed higher soil pH. Deterioration in land quality starts from burning of slashing materials and continues through subsequent stages of shifting cultivation.

  16. Prediction algorithm for amino acid types with their secondary structure in proteins (PLATON) using chemical shifts.

    Science.gov (United States)

    Labudde, D; Leitner, D; Krüger, M; Oschkinat, H

    2003-01-01

    The algorithm PLATON is able to assign sets of chemical shifts derived from a single residue to amino acid types with its secondary structure (amino acid species). A subsequent ranking procedure using optionally two different penalty functions yields predictions for possible amino acid species for the given set of chemical shifts. This was demonstrated in the case of the alpha-spectrin SH3 domain and applied to 9 further protein data sets taken from the BioMagRes database. A database consisting of reference chemical shift patterns (reference CSPs) was generated from assigned chemical shifts of proteins with known 3D-structure. This reference CSP database is used in our approach for extracting distributions of amino acid types with their most likely secondary structure elements (namely alpha-helix, beta-sheet, and coil) for single amino acids by comparison with query CSPs. Results obtained for the 10 investigated proteins indicates that the percentage of correct amino acid species in the first three positions in the ranking list, ranges from 71.4% to 93.2% for the more favorable penalty function. Where only the top result of the ranking list for these 10 proteins is considered, 36.5% to 83.1% of the amino acid species are correctly predicted. The main advantage of our approach, over other methods that rely on average chemical shift values is the ability to increase database content by incorporating newly derived CSPs, and therefore to improve PLATON's performance over time.

  17. Protein structure validation and refinement using amide proton chemical shifts derived from quantum mechanics

    CERN Document Server

    Christensen, Anders S; Borg, Mikael; Boomsma, Wouter; Lindorff-Larsen, Kresten; Hamelryck, Thomas; Jensen, Jan H

    2013-01-01

    We present the ProCS method for the rapid and accurate prediction of protein backbone amide proton chemical shifts - sensitive probes of the geometry of key hydrogen bonds that determine protein structure. ProCS is parameterized against quantum mechanical (QM) calculations and reproduces high level QM results obtained for a small protein with an RMSD of 0.25 ppm (r = 0.94). ProCS is interfaced with the PHAISTOS protein simulation program and is used to infer statistical protein ensembles that reflect experimentally measured amide proton chemical shift values. Such chemical shift-based structural refinements, starting from high-resolution X-ray structures of Protein G, ubiquitin, and SMN Tudor Domain, result in average chemical shifts, hydrogen bond geometries, and trans-hydrogen bond (h3JNC') spin-spin coupling constants that are in excellent agreement with experiment. We show that the structural sensitivity of the QM-based amide proton chemical shift predictions is needed to refine protein structures to this...

  18. Broadband shifts in LFP power spectra are correlated with single-neuron spiking in humans

    Science.gov (United States)

    Manning, Jeremy R.; Jacobs, Joshua; Fried, Itzhak; Kahana, Michael J.

    2010-01-01

    A fundamental question in neuroscience concerns the relation between the spiking of individual neurons and the aggregate electrical activity of neuronal ensembles as seen in local-field potentials (LFPs). Because LFPs reflect both spiking activity and subthreshold events, this question is not simply one of data aggregation. Recording from 20 neurosurgical patients, we directly examined the relation between LFPs and neuronal spiking. Examining 2,030 neurons in widespread brain regions, we found that firing rates were positively correlated with broadband (2 – 150 Hz) shifts in the LFP power spectrum. In contrast, narrowband oscillations correlated both positively and negatively with firing rates at different recording sites. Broadband power shifts were a more-reliable predictor of neuronal spiking than narrowband power shifts. These findings suggest that broadband LFP power provides valuable information concerning neuronal activity beyond that contained in narrowband oscillations. PMID:19864573

  19. Deuterium isotope effects on 13C chemical shifts of negatively charged NH.N systems

    DEFF Research Database (Denmark)

    Hansen, Poul Erik; Pietrzak, Mariusz; Grech, Eugeniusz

    2013-01-01

    Deuterium isotope effects on 13C chemical shifts are investigated in anions of 1,8-bis(4-toluenesulphonamido)naphthalenes together with N,N-(naphthalene-1,8-diyl)bis(2,2,2-trifluoracetamide) all with bis(1,8-dimethylamino)napthaleneH+ as counter ion. These compounds represent both “static......” and equilibrium cases. NMR assignments of the former have been revised. The NH proton is deuteriated. The isotope effects on 13C chemical shifts are rather unusual in these strongly hydrogen bonded systems between a NH and a negatively charged nitrogen atom. The formal four-bond effects are found to be negative...

  20. Protein Structure Validation and Refinement Using Chemical Shifts Derived from Quantum Mechanics

    DEFF Research Database (Denmark)

    Bratholm, Lars Andersen

    In this thesis, my work involving dierent aspects of protein structure determination by computer modeling is presented. Determination of several protein's native fold were carried out with Markov chain Monte Carlo simulations in the PHAISTOS protein structure simulation framework, utilizing...... to within 3 A. Furthermore, a fast quantum mechanics based chemical shift predictor was developed together with methodology for using chemical shifts in structure simulations. The developed predictor was used for renement of several protein structures and for reducing the computational cost of quantum...

  1. Differential dynamic engagement within 24 SH3 domain: peptide complexes revealed by co-linear chemical shift perturbation analysis.

    Directory of Open Access Journals (Sweden)

    Elliott J Stollar

    Full Text Available There is increasing evidence for the functional importance of multiple dynamically populated states within single proteins. However, peptide binding by protein-protein interaction domains, such as the SH3 domain, has generally been considered to involve the full engagement of peptide to the binding surface with minimal dynamics and simple methods to determine dynamics at the binding surface for multiple related complexes have not been described. We have used NMR spectroscopy combined with isothermal titration calorimetry to comprehensively examine the extent of engagement to the yeast Abp1p SH3 domain for 24 different peptides. Over one quarter of the domain residues display co-linear chemical shift perturbation (CCSP behavior, in which the position of a given chemical shift in a complex is co-linear with the same chemical shift in the other complexes, providing evidence that each complex exists as a unique dynamic rapidly inter-converting ensemble. The extent the specificity determining sub-surface of AbpSH3 is engaged as judged by CCSP analysis correlates with structural and thermodynamic measurements as well as with functional data, revealing the basis for significant structural and functional diversity amongst the related complexes. Thus, CCSP analysis can distinguish peptide complexes that may appear identical in terms of general structure and percent peptide occupancy but have significant local binding differences across the interface, affecting their ability to transmit conformational change across the domain and resulting in functional differences.

  2. Predicting Heats of Explosion of Nitroaromatic Compounds through NBO Charges and 15N NMR Chemical Shifts of Nitro Groups

    Directory of Open Access Journals (Sweden)

    Ricardo Infante-Castillo

    2012-01-01

    Full Text Available This work presents a new quantitative model to predict the heat of explosion of nitroaromatic compounds using the natural bond orbital (NBO charge and 15N NMR chemical shifts of the nitro groups (15NNitro as structural parameters. The values of the heat of explosion predicted for 21 nitroaromatic compounds using the model described here were compared with experimental data. The prediction ability of the model was assessed by the leave-one-out cross-validation method. The cross-validation results show that the model is significant and stable and that the predicted accuracy is within 0.146 MJ kg−1, with an overall root mean squared error of prediction (RMSEP below 0.183 MJ kg−1. Strong correlations were observed between the heat of explosion and the charges (R2 = 0.9533 and 15N NMR chemical shifts (R2 = 0.9531 of the studied compounds. In addition, the dependence of the heat of explosion on the presence of activating or deactivating groups of nitroaromatic explosives was analyzed. All calculations, including optimizations, NBO charges, and 15NNitro NMR chemical shifts analyses, were performed using density functional theory (DFT and a 6-311+G(2d,p basis set. Based on these results, this practical quantitative model can be used as a tool in the design and development of highly energetic materials (HEM based on nitroaromatic compounds.

  3. An atomic electronegative distance vector and carbon-13 nuclear magnetic resonance chemical shifts of alcohols and alkanes

    Institute of Scientific and Technical Information of China (English)

    LIU, Shu-Shea; XIA, Zhi-Ning; CAI, Shao-Xi; LIU, Yan

    2000-01-01

    A novel atomic electronegative distance vector (AEDV) has been developed to express the chemical environment of various chemically equivalent carbon atoms in alcohols and alkanes.Combining AEDV and γ parameter, four five-parameter Iinear relationship equations of chemical shift for four types of carbon atoms are created by using multiple linear regression.Correlation coefficients are R = 0.9887, 0.9972, 0.9978 and 0.9968 and roots of mean square error are RMS = 0.906, 0.821, 1.091and 1.091of four types of carbons, i.e., type1,2, 3, and 4 for primary, secondary, tertiary, and quaternary carbons, respectively. The stability and prediction capacity for external samples of four models have been tested by cross- validation.

  4. Energy gap in tunneling spectroscopy: effect of the chemical potential shift

    Science.gov (United States)

    Fedotov, N. I.; Zaitsev-Zotov, S. V.

    2016-12-01

    We study the effect of a shift of the chemical potential level on the tunneling conductance spectra. In the systems with gapped energy spectra, significant chemical-potential dependent distortions of the differential tunneling conductance curves, dI/dV, arise in the gap region. An expression is derived for the correction of the dI/dV, which in a number of cases was found to be large. The sign of the correction depends on the chemical potential level position with respect to the gap. The correction of the dI/dV associated with the chemical potential shift has a nearly linear dependence on the tip-sample separation z and vanishes at z → 0.

  5. Pressure dependence of backbone chemical shifts in the model peptides Ac-Gly-Gly-Xxx-Ala-NH2.

    Science.gov (United States)

    Erlach, Markus Beck; Koehler, Joerg; Crusca, Edson; Kremer, Werner; Munte, Claudia E; Kalbitzer, Hans Robert

    2016-06-01

    For a better understanding of nuclear magnetic resonance (NMR) detected pressure responses of folded as well as unstructured proteins the availability of data from well-defined model systems are indispensable. In this work we report the pressure dependence of chemical shifts of the backbone atoms (1)H(α), (13)C(α) and (13)C' in the protected tetrapeptides Ac-Gly-Gly-Xxx-Ala-NH2 (Xxx one of the 20 canonical amino acids). Contrary to expectation the chemical shifts of these nuclei have a nonlinear dependence on pressure in the range from 0.1 to 200 MPa. The polynomial pressure coefficients B 1 and B 2 are dependent on the type of amino acid studied. The coefficients of a given nucleus show significant linear correlations suggesting that the NMR observable pressure effects in the different amino acids have at least partly the same physical cause. In line with this observation the magnitude of the second order coefficients of nuclei being direct neighbors in the chemical structure are also weakly correlated.

  6. Causal Correlation Functions and Fourier Transforms: Application in Calculating Pressure Induced Shifts

    Science.gov (United States)

    Ma, Q.; Tipping, R. H.; Lavrentieva, N. N.

    2012-01-01

    By adopting a concept from signal processing, instead of starting from the correlation functions which are even, one considers the causal correlation functions whose Fourier transforms become complex. Their real and imaginary parts multiplied by 2 are the Fourier transforms of the original correlations and the subsequent Hilbert transforms, respectively. Thus, by taking this step one can complete the two previously needed transforms. However, to obviate performing the Cauchy principal integrations required in the Hilbert transforms is the greatest advantage. Meanwhile, because the causal correlations are well-bounded within the time domain and band limited in the frequency domain, one can replace their Fourier transforms by the discrete Fourier transforms and the latter can be carried out with the FFT algorithm. This replacement is justified by sampling theory because the Fourier transforms can be derived from the discrete Fourier transforms with the Nyquis rate without any distortions. We apply this method in calculating pressure induced shifts of H2O lines and obtain more reliable values. By comparing the calculated shifts with those in HITRAN 2008 and by screening both of them with the pair identity and the smooth variation rules, one can conclude many of shift values in HITRAN are not correct.

  7. Multilinear relations between {sup 13} C NMR chemical shifts of aliphatic halides; Relacoes lineares multiplas entre deslocamentos quimicos em RMN {sup 13} C de haletos alifaticos

    Energy Technology Data Exchange (ETDEWEB)

    Doyama, Julio Toshimi [UNESP, Botucatu, SP (Brazil). Inst. de Biociencias. Dept. de Quimica e Bioquimica; Tornero, Maria Teresinha Trovarelli [UNESP, Botucatu, SP (Brazil). Inst. de Biociencias. Dept. de Bioestatistica; Yoshida, Massayoshi [UNESP, Araraquara, SP (Brazil). Inst. de Quimica. Dept. de Quimica Organica

    1999-07-01

    The {sup 13} C NMR chemical shifts of the {alpha}, {beta}, {gamma} and {delta} carbons of 17 sets of aliphatic halides (F, Cl, Br and I), including mono, bi and tricyclic compounds, can be reproduced by a linear equation composed with two constants and two variables: {delta}{sub RX} = A{sup *} {delta}{sub R-X2}, where A and B are constants derived from multilinear regression of {sup 13} C chemical shifts observed; {delta}{sub R-X}, the chemical shifts of aliphatic halide (R-X); and {delta}{sub R-X1}, {delta}{sub R-X2} the chemical shifts of other halides. It was observed a better correlation for aliphatic bromides (R-X) by using data of aliphatic fluorides (R-X 1) and aliphatic iodides (R-X 2), resulting R{sup 2} of 0.9989 and average absolute deviation (AVG) of 0.39 ppm. For the chlorides (R-X), the better correlation was observed by using data of bromides (R-X 1) was observed better correlation with data of bromides (R-X 1) and iodides (R-X 2), R{sup 2} of 0.997 and AVG of 1.10 ppm. For the iodides (R-X) was observed better correlation with data of fluorides (R-X 1) and bromides (R-X 2), R{sup 2} of 0.9972 and AVG of 0.60 ppm. (author)

  8. Using NMR chemical shifts to calculate the propensity for structural order and disorder in proteins

    NARCIS (Netherlands)

    Tamiola, Kamil; Mulder, Frans A. A.

    2012-01-01

    NMR spectroscopy offers the unique possibility to relate the structural propensities of disordered proteins and loop segments of folded peptides to biological function and aggregation behaviour. Backbone chemical shifts are ideally suited for this task, provided that appropriate reference data are a

  9. Isotope effects on chemical shifts in the study of intramolecular hydrogen bonds

    DEFF Research Database (Denmark)

    Hansen, Poul Erik

    2015-01-01

    The paper deals with the use of isotope effects on chemical shifts in characterizing intramolecular hydrogen bonds. Both so-called resonance-assisted (RAHB) and non-RAHB systems are treated. The importance of RAHB will be discussed. Another very important issue is the borderline between “static” ...

  10. Can the current density map topology be extracted from the nucleus independent chemical shifts?

    NARCIS (Netherlands)

    Van Damme, Sofie; Acke, Guillaume; Havenith, Remco W. A.; Bultinck, Patrick

    2016-01-01

    Aromatic compounds are characterised by the presence of a ring current when in a magnetic field. As a consequence, current density maps are used to assess (the degree of) aromaticity of a compound. However, often a more discrete set of so-called Nucleus Independent Chemical Shift (NICS) values is us

  11. Computation of Chemical Shifts for Paramagnetic Molecules: A Laboratory Experiment for the Undergraduate Curriculum

    Science.gov (United States)

    Pritchard, Benjamin P.; Simpson, Scott; Zurek, Eva; Autschbach, Jochen

    2014-01-01

    A computational experiment investigating the [superscript 1]H and [superscript 13]C nuclear magnetic resonance (NMR) chemical shifts of molecules with unpaired electrons has been developed and implemented. This experiment is appropriate for an upper-level undergraduate laboratory course in computational, physical, or inorganic chemistry. The…

  12. The statistical shift of the chemical potential causing anomalous conductivity in hydrogenated microcrystalline silicon

    NARCIS (Netherlands)

    Lof, R.W.; Schropp, R.E.I.

    2010-01-01

    The behavior of the electrical conductivity in hydrogenated microcrystalline silicon (μ c-Si:H) that is frequently observed is explained by considering the statistical shift in the chemical potential as a function of the crystalline fraction (Xc), the dangling bond density (N db), and the doping den

  13. Protein structure validation and refinement using amide proton chemical shifts derived from quantum mechanics

    DEFF Research Database (Denmark)

    Christensen, Anders Steen; Linnet, Troels Emtekær; Borg, Mikael;

    2013-01-01

    We present the ProCS method for the rapid and accurate prediction of protein backbone amide proton chemical shifts - sensitive probes of the geometry of key hydrogen bonds that determine protein structure. ProCS is parameterized against quantum mechanical (QM) calculations and reproduces high level...

  14. A Physically Based Correlation of Irradiation-Induced Transition Temperature Shifts for RPV Steels

    Energy Technology Data Exchange (ETDEWEB)

    Eason, Ernest D. [Modeling and Computing Services, LLC; Odette, George Robert [UCSB; Nanstad, Randy K [ORNL; Yamamoto, Takuya [ORNL

    2007-11-01

    The reactor pressure vessels (RPVs) of commercial nuclear power plants are subject to embrittlement due to exposure to high-energy neutrons from the core, which causes changes in material toughness properties that increase with radiation exposure and are affected by many variables. Irradiation embrittlement of RPV beltline materials is currently evaluated using Regulatory Guide 1.99 Revision 2 (RG1.99/2), which presents methods for estimating the shift in Charpy transition temperature at 30 ft-lb (TTS) and the drop in Charpy upper shelf energy (ΔUSE). The purpose of the work reported here is to improve on the TTS correlation model in RG1.99/2 using the broader database now available and current understanding of embrittlement mechanisms. The USE database and models have not been updated since the publication of NUREG/CR-6551 and, therefore, are not discussed in this report. The revised embrittlement shift model is calibrated and validated on a substantially larger, better-balanced database compared to prior models, including over five times the amount of data used to develop RG1.99/2. It also contains about 27% more data than the most recent update to the surveillance shift database, in 2000. The key areas expanded in the current database relative to the database available in 2000 are low-flux, low-copper, and long-time, high-fluence exposures, all areas that were previously relatively sparse. All old and new surveillance data were reviewed for completeness, duplicates, and discrepancies in cooperation with the American Society for Testing and Materials (ASTM) Subcommittee E10.02 on Radiation Effects in Structural Materials. In the present modeling effort, a 10% random sample of data was reserved from the fitting process, and most aspects of the model were validated with that sample as well as other data not used in calibration. The model is a hybrid, incorporating both physically motivated features and empirical calibration to the U.S. power reactor surveillance

  15. Elucidating the Link between NMR Chemical Shifts and Electronic Structure in d(0) Olefin Metathesis Catalysts.

    Science.gov (United States)

    Halbert, Stéphanie; Copéret, Christophe; Raynaud, Christophe; Eisenstein, Odile

    2016-02-24

    The nucleophilic carbon of d(0) Schrock alkylidene metathesis catalysts, [M] = CHR, display surprisingly low downfield chemical shift (δ(iso)) and large chemical shift anisotropy. State-of-the-art four-component relativistic calculations of the chemical shift tensors combined with a two-component analysis in terms of localized orbitals allow a molecular-level understanding of their orientations, the magnitude of their principal components (δ11 > δ22 > δ33) and associated δ(iso). This analysis reveals the dominating influence of the paramagnetic contribution yielding a highly deshielded alkylidene carbon. The largest paramagnetic contribution, which originates from the coupling of alkylidene σ(MC) and π*(MC) orbitals under the action of the magnetic field, is analogous to that resulting from coupling σ(CC) and π*(CC) in ethylene; thus, δ11 is in the MCH plane and is perpendicular to the MC internuclear direction. The higher value of carbon-13 δ(iso) in alkylidene complexes relative to ethylene is thus due to the smaller energy gap between σ(MC) and π*(MC) vs this between σ(CC) and π*(CC) in ethylene. This effect also explains why the highest value of δ(iso) is observed for Mo and the lowest for Ta, the values for W and Re being in between. In the presence of agostic interaction, the chemical shift tensor principal components orientation (δ22 or δ33 parallel or perpendicular to π(MX)) is influenced by the MCH angle because it determines the orientation of the alkylidene CHR fragment relative to the MC internuclear axis. The orbital analysis shows how the paramagnetic terms, understood with a localized bond model, determine the chemical shift tensor and thereby δ(iso).

  16. Magnetic Shift of the Chemical Freeze-out and Electric Charge Fluctuations

    Science.gov (United States)

    Fukushima, Kenji; Hidaka, Yoshimasa

    2016-09-01

    We discuss the effect of a strong magnetic field on the chemical freeze-out points in ultrarelativistic heavy-ion collisions. As a result of inverse magnetic catalysis or magnetic inhibition, the crossover onset to hot and dense matter out of quarks and gluons should be shifted to a lower temperature. To quantify this shift we employ the hadron resonance gas model and an empirical condition for the chemical freeze-out. We point out that the charged particle abundances are significantly affected by the magnetic field so that the electric charge fluctuation is largely enhanced, especially at high baryon density. The charge conservation partially cancels the enhancement, but our calculation shows that the electric charge fluctuation could serve as a magnetometer. We find that the fluctuation exhibits a crossover behavior rapidly increased for e B ≳(0.4 GeV )2, while the charge chemical potential has smoother behavior with an increasing magnetic field.

  17. Thalassiosira spp. community composition shifts in response to chemical and physical forcing in the northeast Pacific Ocean.

    Science.gov (United States)

    Chappell, P Dreux; Whitney, Leeann P; Haddock, Traci L; Menden-Deuer, Susanne; Roy, Eric G; Wells, Mark L; Jenkins, Bethany D

    2013-01-01

    Diatoms are genetically diverse unicellular photosynthetic eukaryotes that are key primary producers in the ocean. Many of the over 100 extant diatom species in the cosmopolitan genus Thalassiosira are difficult to distinguish in mixed populations using light microscopy. Here, we examine shifts in Thalassiosira spp. composition along a coastal to open ocean transect that encountered a 3-month-old Haida eddy in the northeast Pacific Ocean. To quantify shifts in Thalassiosira species composition, we developed a targeted automated ribosomal intergenic spacer analysis (ARISA) method to identify Thalassiosira spp. in environmental samples. As many specific fragment lengths are indicative of individual Thalassiosira spp., the ARISA method is a useful screening tool to identify changes in the relative abundance and distribution of specific species. The method also enabled us to assess changes in Thalassiosira community composition in response to chemical and physical forcing. Thalassiosira spp. community composition in the core of a 3-month-old Haida eddy remained largely (>80%) similar over a 2-week period, despite moving 24 km southwestward. Shifts in Thalassiosira species correlated with changes in dissolved iron (Fe) and temperature throughout the sampling period. Simultaneously tracking community composition and relative abundance of Thalassiosira species within the physical and chemical context they occurred allowed us to identify quantitative linkages between environmental conditions and community response.

  18. Thalassiosira spp. community composition shifts in response to chemical and physical forcing in the northeast Pacific Ocean.

    Directory of Open Access Journals (Sweden)

    Phoebe Dreux Chappell

    2013-09-01

    Full Text Available Diatoms are genetically diverse unicellular photosynthetic eukaryotes that are key primary producers in the ocean. Many of the over 100 extant diatom species in the cosmopolitan genus Thalassiosira are difficult to distinguish in mixed populations using light microscopy. Here we examine shifts in Thalassiosira spp. composition along a coastal to open ocean transect that encountered a three-month-old Haida eddy in the northeast Pacific Ocean. To quantify shifts in Thalassiosira species composition, we developed a targeted automated ribosomal intergenic spacer analysis (ARISA method to identify Thalassiosira spp. in environmental samples. As many specific fragment lengths are indicative of individual Thalassiosira spp., the ARISA method is a useful screening tool to identify changes in the relative abundance and distribution of specific species. The method also enabled us to assess changes in Thalassiosira community composition in response to chemical and physical forcing. Thalassiosira spp. community composition in the core of a three-month-old Haida eddy remained largely (>80% similar over a two-week period, despite moving 24 km southwestward. Shifts in Thalassiosira species correlated with changes in dissolved iron (Fe and temperature throughout the sampling period. Simultaneously tracking community composition and relative abundance of Thalassiosira species within the physical and chemical context they occurred allowed us to identify quantitative linkages between environmental conditions and community response.

  19. Protein structural information derived from NMR chemical shift with the neural network program TALOS-N.

    Science.gov (United States)

    Shen, Yang; Bax, Ad

    2015-01-01

    Chemical shifts are obtained at the first stage of any protein structural study by NMR spectroscopy. Chemical shifts are known to be impacted by a wide range of structural factors, and the artificial neural network based TALOS-N program has been trained to extract backbone and side-chain torsion angles from (1)H, (15)N, and (13)C shifts. The program is quite robust and typically yields backbone torsion angles for more than 90 % of the residues and side-chain χ 1 rotamer information for about half of these, in addition to reliably predicting secondary structure. The use of TALOS-N is illustrated for the protein DinI, and torsion angles obtained by TALOS-N analysis from the measured chemical shifts of its backbone and (13)C(β) nuclei are compared to those seen in a prior, experimentally determined structure. The program is also particularly useful for generating torsion angle restraints, which then can be used during standard NMR protein structure calculations.

  20. Stereoelectronic effects on 1H nuclear magnetic resonance chemical shifts in methoxybenzenes

    DEFF Research Database (Denmark)

    Lambert, Maja; Olsen, Lars; Jaroszewski, Jerzy W

    2006-01-01

    the Ar-OCH3 torsion out of the ring plane, resulting in large stereoelectronic effects on the chemical shift of Hpara. Conformational searches and geometry optimizations for 3-16 at the B3LYP/6-31G** level, followed by B3LYP/6-311++G(2d,2p) calculations for all low-energy conformers, gave excellent......Investigation of all O-methyl ethers of 1,2,3-benzenetriol and 4-methyl-1,2,3-benzenetriol (3-16) by 1H NMR spectroscopy and density-functional calculations disclosed practically useful conformational effects on 1H NMR chemical shifts in the aromatic ring. While the conversion of phenol (2......) to anisole (1) causes only small positive changes of 1H NMR chemical shifts (Delta delta Hmeta > Hpara, the experimental O-methylation induced shifts in ortho-disubstituted phenols are largest for Hpara, Delta delta equals; 0.19 +/- 0.02 ppm (n = 11...

  1. Noninvasive Monitoring of Training Induced Muscle Adaptation with -MRS: Fibre Type Shifts Correlate with Metabolic Changes

    Directory of Open Access Journals (Sweden)

    Eike Hoff

    2013-01-01

    Full Text Available Purpose. To evaluate training induced metabolic changes noninvasively with magnetic resonance spectroscopy (-MRS for measuring muscle fibre type adaptation. Methods. Eleven volunteers underwent a 24-week training, consisting of speed-strength, endurance, and detraining (each 8 weeks. Prior to and following each training period, needle biopsies and -MRS of the resting gastrocnemius muscle were performed. Fibre type distribution was analyzed histologically and tested for correlation with the ratios of high energy phosphates ([PCr]/[], [PCr]/[βATP] and [PCr + ]/[βATP]. The correlation between the changes of the -MRS parameters during training and the resulting changes in fibre composition were also analysed. Results. We observed an increased type-II-fibre proportion after speed-strength and detraining. After endurance training the percentage of fast-twitch fibres was reduced. The progression of the [PCr]/[]-ratio was similar to that of the fast-twitch fibres during the training. We found a correlation between the type-II-fibre proportion and [PCr]/[] (, or [PCr]/[βATP] (, ; the correlations between its changes (delta and the fibre-shift were significant as well (delta[PCr]/[] , delta[PCr]/[βATP] , . Conclusion. Shifts in fibre type composition and high energy phosphate metabolite content covary in human gastrocnemius muscle. Therefore -MRS might be a feasible method for noninvasive monitoring of exercise-induced fibre type transformation.

  2. Predicting paramagnetic 1H NMR chemical shifts and state-energy separations in spin-crossover host-guest systems.

    Science.gov (United States)

    Isley, William C; Zarra, Salvatore; Carlson, Rebecca K; Bilbeisi, Rana A; Ronson, Tanya K; Nitschke, Jonathan R; Gagliardi, Laura; Cramer, Christopher J

    2014-06-14

    The behaviour of metal-organic cages upon guest encapsulation can be difficult to elucidate in solution. Paramagnetic metal centres introduce additional dispersion of signals that is useful for characterisation of host-guest complexes in solution using nuclear magnetic resonance (NMR). However, paramagnetic centres also complicate spectral assignment due to line broadening, signal integration error, and large changes in chemical shifts, which can be difficult to assign even for known compounds. Quantum chemical predictions can provide information that greatly facilitates the assignment of NMR signals and identification of species present. Here we explore how the prediction of paramagnetic NMR spectra may be used to gain insight into the spin crossover (SCO) properties of iron(II)-based metal organic coordination cages, specifically examining how the structure of the local metal coordination environment affects SCO. To represent the tetrahedral metal-organic cage, a model system is generated by considering an isolated metal-ion vertex: fac-ML3(2+) (M = Fe(II), Co(II); L = N-phenyl-2-pyridinaldimine). The sensitivity of the (1)H paramagnetic chemical shifts to local coordination environments is assessed and utilised to shed light on spin crossover behaviour in iron complexes. Our data indicate that expansion of the metal coordination sphere must precede any thermal SCO. An attempt to correlate experimental enthalpies of SCO with static properties of bound guests shows that no simple relationship exists, and that effects are likely due to nuanced dynamic response to encapsulation.

  3. 13C-detected NMR experiments for measuring chemical shifts and coupling constants in nucleic acid bases.

    Science.gov (United States)

    Fiala, Radovan; Sklenár, Vladimír

    2007-10-01

    The paper presents a set of two-dimensional experiments that utilize direct (13)C detection to provide proton-carbon, carbon-carbon and carbon-nitrogen correlations in the bases of nucleic acids. The set includes a (13)C-detected proton-carbon correlation experiment for the measurement of (13)C-(13)C couplings, the CaCb experiment for correlating two quaternary carbons, the HCaCb experiment for the (13)C-(13)C correlations in cases where one of the carbons has a proton attached, the HCC-TOCSY experiment for correlating a proton with a network of coupled carbons, and a (13)C-detected (13)C-(15)N correlation experiment for detecting the nitrogen nuclei that cannot be detected via protons. The IPAP procedure is used for extracting the carbon-carbon couplings and/or carbon decoupling in the direct dimension, while the S(3)E procedure is preferred in the indirect dimension of the carbon-nitrogen experiment to obtain the value of the coupling constant. The experiments supply accurate values of (13)C and (15)N chemical shifts and carbon-carbon and carbon-nitrogen coupling constants. These values can help to reveal structural features of nucleic acids either directly or via induced changes when the sample is dissolved in oriented media.

  4. Two-Dimensional Proton Chemical-Shift Imaging of Human Muscle Metabolites

    Science.gov (United States)

    Hu, Jiani; Willcott, M. Robert; Moore, Gregory J.

    1997-06-01

    Large lipid signals and strong susceptibility gradients introduced by muscle-bone interfaces represent major technical challenges forin vivoproton MRS of human muscle. Here, the demonstration of two-dimensional proton chemical-shift imaging of human muscle metabolites is presented. This technique utilizes a chemical-shift-selective method for water and lipid suppression and automatic shimming for optimal homogeneity of the magnetic field. The 2D1H CSI technique described facilitates the acquisition of high-spatial-resolution spectra, and allows one to acquire data from multiple muscle groups in a single experiment. A preliminary investigation utilizing this technique in healthy adult males (n= 4) revealed a highly significant difference in the ratio of the creatine to trimethylamine resonance between the fast and slow twitch muscle groups examined. The technique is robust, can be implemented on a commercial scanner with relative ease, and should prove to be a useful tool for both clinical and basic investigators.

  5. Modeling proteins using a super-secondary structure library and NMR chemical shift information.

    Science.gov (United States)

    Menon, Vilas; Vallat, Brinda K; Dybas, Joseph M; Fiser, Andras

    2013-06-04

    A remaining challenge in protein modeling is to predict structures for sequences with no sequence similarity to any experimentally solved structure. Based on earlier observations, the library of protein backbone supersecondary structure motifs (Smotifs) saturated about a decade ago. Therefore, it should be possible to build any structure from a combination of existing Smotifs with the help of limited experimental data that are sufficient to relate the backbone conformations of Smotifs between target proteins and known structures. Here, we present a hybrid modeling algorithm that relies on an exhaustive Smotif library and on nuclear magnetic resonance chemical shift patterns without any input of primary sequence information. In a test of 102 proteins, the algorithm delivered 90 homology-model-quality models, among them 24 high-quality ones, and a topologically correct solution for almost all cases. The current approach opens a venue to address the modeling of larger protein structures for which chemical shifts are available.

  6. PACSY, a relational database management system for protein structure and chemical shift analysis.

    Science.gov (United States)

    Lee, Woonghee; Yu, Wookyung; Kim, Suhkmann; Chang, Iksoo; Lee, Weontae; Markley, John L

    2012-10-01

    PACSY (Protein structure And Chemical Shift NMR spectroscopY) is a relational database management system that integrates information from the Protein Data Bank, the Biological Magnetic Resonance Data Bank, and the Structural Classification of Proteins database. PACSY provides three-dimensional coordinates and chemical shifts of atoms along with derived information such as torsion angles, solvent accessible surface areas, and hydrophobicity scales. PACSY consists of six relational table types linked to one another for coherence by key identification numbers. Database queries are enabled by advanced search functions supported by an RDBMS server such as MySQL or PostgreSQL. PACSY enables users to search for combinations of information from different database sources in support of their research. Two software packages, PACSY Maker for database creation and PACSY Analyzer for database analysis, are available from http://pacsy.nmrfam.wisc.edu.

  7. Identifying Stereoisomers by ab-initio Calculation of Secondary Isotope Shifts on NMR Chemical Shieldings

    Directory of Open Access Journals (Sweden)

    Karl-Heinz Böhm

    2014-04-01

    Full Text Available We present ab-initio calculations of secondary isotope effects on NMR chemical shieldings. The change of the NMR chemical shift of a certain nucleus that is observed if another nucleus is replaced by a different isotope can be calculated by computing vibrational corrections on the NMR parameters using electronic structure methods. We demonstrate that the accuracy of the computational results is sufficient to even distinguish different conformers. For this purpose, benchmark calculations for fluoro(2-2Hethane in gauche and antiperiplanar conformation are carried out at the HF, MP2 and CCSD(T level of theory using basis sets ranging from double- to quadruple-zeta quality. The methodology is applied to the secondary isotope shifts for 2-fluoronorbornane in order to resolve an ambiguity in the literature on the assignment of endo- and exo-2-fluoronorbornanes with deuterium substituents in endo-3 and exo-3 positions, also yielding insight into mechanistic details of the corresponding synthesis.

  8. First-principles calculation of core-level binding energy shift in surface chemical processes

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Combined with third generation synchrotron radiation light sources, X-ray photoelectron spectroscopy (XPS) with higher energy resolution, brilliance, enhanced surface sensitivity and photoemission cross section in real time found extensive applications in solid-gas interface chemistry. This paper reports the calculation of the core-level binding energy shifts (CLS) using the first-principles density functional theory. The interplay between the CLS calculations and XPS measurements to uncover the structures, adsorption sites and chemical reactions in complex surface chemical processes are highlight. Its application on clean low index (111) and vicinal transition metal surfaces, molecular adsorption in terms of sites and configuration, and reaction kinetics are domonstrated.

  9. Crime Scene Investigation: Clinical Application of Chemical Shift Imaging as a Problem Solving Tool

    Science.gov (United States)

    2016-02-26

    MDW/SGVU SUBJECT: Professional Presentation Approva l 26 FEB 2016 1. Your paper, entitled Crime Scene Investigation: Clinical Aoolication of...or technical information as a publication/presentation, a new 59 MDW Form 3039 must be submitted for review and approval.] Crime Scene Investiga...tion: Clinical Application of Chemical Shift Imaging as a Problem Solving Tool 1. TITLE OF MATERIAL TO BE PUBLISHED OR PRESENTED Crime Scene

  10. Chemical shift selective magnetic resonance imaging of the optic nerve in patients with acute optic neuritis

    Energy Technology Data Exchange (ETDEWEB)

    Larsson, H.B.W.; Thomsen, C.; Frederiksen, J.; Henriksen, O.; Olesen, J.

    Optic neuritis is often the first manifestion of multiple sclerosis (MS). Sixteen patients with acute optic neuritis and one patient with benign intracranial hypertension (BIH) were investigated by magnetic resonance imaging, using a chemical shift selective double spin echo sequence. In 3 of the 16 patients, abnormalities were seen. In one patient with bilateral symptoms, signal hyperintensity and swelling of the right side of the chiasm were found. In another patient the optic nerve was found diffusely enlarged with only a marginally increased signal in the second echo. In the third patient an area of signal hyperintensity and swelling was seen in the left optic nerve. In the patient with BIH the subarachnoid space which surrounds the optic nerves was enlarged. Even using this refined pulse sequence, avoiding the major artefact in imaging the optic nerve, the chemical shift artefact, lesions were only shown in 3/16 (19%) of the patients with optic neuritis. Nevertheless, the presented chemical shift selective double spin echo sequence may be of great value for detection of retrobulbar lesions.

  11. Substituent effects in the 13C NMR chemical shifts of alpha-mono-substituted acetonitriles.

    Science.gov (United States)

    Reis, Adriana K C A; Rittner, Roberto

    2007-03-01

    13C chemical shifts empirical calculations, through a very simple additivity relationship, for the alpha-methylene carbon of some alpha-mono-substituted acetonitriles, Y-CH(2)-CN (Y=H, F, Cl, Br, I, OMe, OEt, SMe, SEt, NMe(2), NEt(2), Me and Et), lead to similar, or even better, results in comparison to the reported values obtained through Quantum Mechanics methods. The observed deviations, for some substituents, are very similar for both approaches. This divergence between experimental and calculated, either empirically or theoretically, values are smaller than for the corresponding acetones, amides, acetic acids and methyl esters, which had been named non-additivity effects (or intramolecular interaction chemical shifts, ICS) and attributed to some orbital interactions. Here, these orbital interactions do not seem to be the main reason for the non-additivity effects in the empirical calculations, which must be due solely to the magnetic anisotropy of the heavy atom present in the substituent. These deviations, which were also observed in the theoretical calculations, were attributed in that case to the non-inclusion of relativistic effects and spin-orbit coupling in the Hamiltonian. Some divergence is also observed for the cyano carbon chemical shifts, probably due to the same reasons.

  12. Double-image encryption based on joint transform correlation and phase-shifting interferometry

    Institute of Scientific and Technical Information of China (English)

    Lina Shen; Jun Li; Hongsen Chang

    2007-01-01

    An image encryption method combining the joint transform correlator (JTC) architecture with phaseshifting interferometry to realize double random-phase encoding is proposed. The encrypted field and the decrypting key are registered as holograms by phase-shifting interferometry. This method can encrypt two images simultaneously to improve the encryption efficiency of the methods based on JTC architecture, and eliminate the system alignment constraint of the methods based on Mach-Zehnder interferometer (MZI)architecture. Its feasibility and validity are verified by computer simulations. Moreover, image encryption and decryption can be achieved at high speed optically or digitally. The encrypted data are suitable for Internet transmission.

  13. Predictions of the fluorine NMR chemical shifts of perfluorinated carboxylic acids, CnF(2n+1)COOH (n = 6-8).

    Science.gov (United States)

    Liu, Zizhong; Goddard, John D

    2009-12-17

    Perfluorinated carboxylic acids (PFCAs) are a class of persistent environmental pollutants. Commercially available PFCAs are mixtures of linear and branched isomers, possibly with impurities. Different isomers have different physical and chemical properties and toxicities. However, little is known about the properties and the finer details of the structures of the individual branched isomers. Full geometry optimizations for the linear n-alkane (C(6)-C(27)) PFCAs indicated that all have helical structures. The helical angle increases slightly with increasing chain length, from 16.3 degrees in C(6)F(13)COOH to 17.0 degrees in C(27)F(55)COOH. This study predicts (19)F NMR parameters for 69 linear and branched isomers of the perfluoro carboxylic acids C(6)F(13)COOH, C(7)F(15)COOH, and C(8)F(17)COOH. B3LYP-GIAO/6-31++G(d,p)//B3LYP/6-31G(d,p) was used for the NMR calculations with analysis of the chemical shifts by the natural bond orbital method. The predictions of the (19)F chemical shifts revealed the differences among the CF(3), CF(2), and CF groups. In general, the absolute values for the chemical shifts for the CF(3) group are smaller than 90 ppm, for the CF larger than 160 ppm, and for the CF(2) between 110 and 130 ppm. The chemical shifts of the branched isomers are smaller in magnitude than the linear ones. The decrease is correlated with the steric hindrance of the CF(3) groups, the more hindered the CF(3), the greater the decrease in the (19)F chemical shifts. The predicted (19)F chemical shifts are similar to those for analogous perfluoro compounds with other terminal functional groups such as -SO(3)H or -SO(3)NH(2)CH(2)CH(3).

  14. Canonical correlations between chemical and energetic characteristics of lignocellulosic wastes

    Directory of Open Access Journals (Sweden)

    Thiago de Paula Protásio

    2012-09-01

    Full Text Available Canonical correlation analysis is a statistical multivariate procedure that allows analyzing linear correlation that may exist between two groups or sets of variables (X and Y. This paper aimed to provide canonical correlation analysis between a group comprised of lignin and total extractives contents and higher heating value (HHV with a group of elemental components (carbon, hydrogen, nitrogen and sulfur for lignocellulosic wastes. The following wastes were used: eucalyptus shavings; pine shavings; red cedar shavings; sugar cane bagasse; residual bamboo cellulose pulp; coffee husk and parchment; maize harvesting wastes; and rice husk. Only the first canonical function was significant, but it presented a low canonical R². High carbon, hydrogen and sulfur contents and low nitrogen contents seem to be related to high total extractives contents of the lignocellulosic wastes. The preliminary results found in this paper indicate that the canonical correlations were not efficient to explain the correlations between the chemical elemental components and lignin contents and higher heating values.

  15. Temperature dependence of contact and dipolar NMR chemical shifts in paramagnetic molecules.

    Science.gov (United States)

    Martin, Bob; Autschbach, Jochen

    2015-02-07

    Using a recently proposed equation for NMR nuclear magnetic shielding for molecules with unpaired electrons [A. Soncini and W. Van den Heuvel, J. Chem. Phys. 138, 021103 (2013)], equations for the temperature (T) dependent isotropic shielding for multiplets with an effective spin S equal to 1/2, 1, 3/2, 2, and 5/2 in terms of electron paramagnetic resonance spin Hamiltonian parameters are derived and then expanded in powers of 1/T. One simplifying assumption used is that a matrix derived from the zero-field splitting (ZFS) tensor and the Zeeman coupling matrix (g-tensor) share the same principal axis system. The influence of the rhombic ZFS parameter E is only investigated for S = 1. Expressions for paramagnetic contact shielding (from the isotropic part of the hyperfine coupling matrix) and pseudo-contact or dipolar shielding (from the anisotropic part of the hyperfine coupling matrix) are considered separately. The leading order is always 1/T. A temperature dependence of the contact shielding as 1/T and of the dipolar shielding as 1/T(2), which is sometimes assumed in the assignment of paramagnetic chemical shifts, is shown to arise only if S ≥ 1 and zero-field splitting is appreciable, and only if the Zeeman coupling matrix is nearly isotropic (Δg = 0). In such situations, an assignment of contact versus dipolar shifts may be possible based only on linear and quadratic fits of measured variable-temperature chemical shifts versus 1/T. Numerical data are provided for nickelocene (S = 1). Even under the assumption of Δg = 0, a different leading order of contact and dipolar shifts in powers of 1/T is not obtained for S = 3/2. When Δg is not very small, dipolar and contact shifts both depend in leading order in 1/T in all cases, with sizable contributions in order 1/T(n) with n = 2 and higher.

  16. Time-Shift Correlation Algorithm for P300 Event Related Potential Brain-Computer Interface Implementation.

    Science.gov (United States)

    Liu, Ju-Chi; Chou, Hung-Chyun; Chen, Chien-Hsiu; Lin, Yi-Tseng; Kuo, Chung-Hsien

    2016-01-01

    A high efficient time-shift correlation algorithm was proposed to deal with the peak time uncertainty of P300 evoked potential for a P300-based brain-computer interface (BCI). The time-shift correlation series data were collected as the input nodes of an artificial neural network (ANN), and the classification of four LED visual stimuli was selected as the output node. Two operating modes, including fast-recognition mode (FM) and accuracy-recognition mode (AM), were realized. The proposed BCI system was implemented on an embedded system for commanding an adult-size humanoid robot to evaluate the performance from investigating the ground truth trajectories of the humanoid robot. When the humanoid robot walked in a spacious area, the FM was used to control the robot with a higher information transfer rate (ITR). When the robot walked in a crowded area, the AM was used for high accuracy of recognition to reduce the risk of collision. The experimental results showed that, in 100 trials, the accuracy rate of FM was 87.8% and the average ITR was 52.73 bits/min. In addition, the accuracy rate was improved to 92% for the AM, and the average ITR decreased to 31.27 bits/min. due to strict recognition constraints.

  17. Time-Shift Correlation Algorithm for P300 Event Related Potential Brain-Computer Interface Implementation

    Directory of Open Access Journals (Sweden)

    Ju-Chi Liu

    2016-01-01

    Full Text Available A high efficient time-shift correlation algorithm was proposed to deal with the peak time uncertainty of P300 evoked potential for a P300-based brain-computer interface (BCI. The time-shift correlation series data were collected as the input nodes of an artificial neural network (ANN, and the classification of four LED visual stimuli was selected as the output node. Two operating modes, including fast-recognition mode (FM and accuracy-recognition mode (AM, were realized. The proposed BCI system was implemented on an embedded system for commanding an adult-size humanoid robot to evaluate the performance from investigating the ground truth trajectories of the humanoid robot. When the humanoid robot walked in a spacious area, the FM was used to control the robot with a higher information transfer rate (ITR. When the robot walked in a crowded area, the AM was used for high accuracy of recognition to reduce the risk of collision. The experimental results showed that, in 100 trials, the accuracy rate of FM was 87.8% and the average ITR was 52.73 bits/min. In addition, the accuracy rate was improved to 92% for the AM, and the average ITR decreased to 31.27 bits/min. due to strict recognition constraints.

  18. Complete (1)H and (13)C NMR chemical shift assignments of mono-, di-, and trisaccharides as basis for NMR chemical shift predictions of polysaccharides using the computer program casper.

    Science.gov (United States)

    Roslund, Mattias U; Säwén, Elin; Landström, Jens; Rönnols, Jerk; Jonsson, K Hanna M; Lundborg, Magnus; Svensson, Mona V; Widmalm, Göran

    2011-08-16

    The computer program casper uses (1)H and (13)C NMR chemical shift data of mono- to trisaccharides for the prediction of chemical shifts of oligo- and polysaccharides. In order to improve the quality of these predictions the (1)H and (13)C, as well as (31)P when applicable, NMR chemical shifts of 30 mono-, di-, and trisaccharides were assigned. The reducing sugars gave two distinct sets of NMR resonances due to the α- and β-anomeric forms. In total 35 (1)H and (13)C NMR chemical shift data sets were obtained from the oligosaccharides. One- and two-dimensional NMR experiments were used for the chemical shift assignments and special techniques were employed in some cases such as 2D (1)H,(13)C-HSQC Hadamard Transform methodology which was acquired approximately 45 times faster than a regular t(1) incremented (1)H,(13)C-HSQC experiment and a 1D (1)H,(1)H-CSSF-TOCSY experiment which was able to distinguish spin-systems in which the target protons were only 3.3Hz apart. The (1)H NMR chemical shifts were subsequently refined using total line-shape analysis with the PERCH NMR software. The acquired NMR data were then utilized in the casper program (http://www.casper.organ.su.se/casper/) for NMR chemical shift predictions of the O-antigen polysaccharides from Klebsiella O5, Shigella flexneri serotype X, and Salmonella arizonae O62. The data were compared to experimental data of the polysaccharides from the two former strains and the lipopolysaccharide of the latter strain showing excellent agreement between predicted and experimental (1)H and (13)C NMR chemical shifts.

  19. Parameter-free calculation of K alpha chemical shifts for Al, Si, and Ge oxides

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper

    2001-01-01

    The chemical shifts of the K alpha radiation line from Al, Si, and Ge ions between their elemental and oxide forms are calculated within the framework of density functional theory using ultrasoft pseudopotentials. It is demonstrated that this theoretical approach yields quantitatively accurate...... results fur the systems investigated, provided that relaxations of the valence electrons upon the core-hole transition are properly accounted for. Therefore, such calculations provide a powerful tool for identification of impurity states based on x-ray fluorescence data. Results for an Al impurity...

  20. NMR Chemical Shift Ranges of Urine Metabolites in Various Organic Solvents

    Directory of Open Access Journals (Sweden)

    Benjamin Görling

    2016-09-01

    Full Text Available Signal stability is essential for reliable multivariate data analysis. Urine samples show strong variance in signal positions due to inter patient differences. Here we study the exchange of the solvent of a defined urine matrix and how it affects signal and integral stability of the urinary metabolites by NMR spectroscopy. The exchange solvents were methanol, acetonitrile, dimethyl sulfoxide, chloroform, acetone, dichloromethane, and dimethyl formamide. Some of these solvents showed promising results with a single batch of urine. To evaluate further differences between urine samples, various acid, base, and salt solutions were added in a defined way mimicking to some extent inter human differences. Corresponding chemical shift changes were monitored.

  1. NMR Chemical Shift Ranges of Urine Metabolites in Various Organic Solvents

    Science.gov (United States)

    Görling, Benjamin; Bräse, Stefan; Luy, Burkhard

    2016-01-01

    Signal stability is essential for reliable multivariate data analysis. Urine samples show strong variance in signal positions due to inter patient differences. Here we study the exchange of the solvent of a defined urine matrix and how it affects signal and integral stability of the urinary metabolites by NMR spectroscopy. The exchange solvents were methanol, acetonitrile, dimethyl sulfoxide, chloroform, acetone, dichloromethane, and dimethyl formamide. Some of these solvents showed promising results with a single batch of urine. To evaluate further differences between urine samples, various acid, base, and salt solutions were added in a defined way mimicking to some extent inter human differences. Corresponding chemical shift changes were monitored. PMID:27598217

  2. Three model space experiments on chemical reactions. [Gibbs adsorption, equilibrium shift and electrodeposition

    Science.gov (United States)

    Grodzka, P.; Facemire, B.

    1977-01-01

    Three investigations conducted aboard Skylab IV and Apollo-Soyuz involved phenomena that are of interest to the biochemistry community. The formaldehyde clock reaction and the equilibrium shift reaction experiments conducted aboard Apollo Soyuz demonstrate the effect of low-g foams or air/liquid dispersions on reaction rate and chemical equilibrium. The electrodeposition reaction experiment conducted aboard Skylab IV demonstrate the effect of a low-g environment on an electrochemical displacement reaction. The implications of the three space experiments for various applications are considered.

  3. Optimal voxel size for measuring global gray and white matter proton metabolite concentrations using chemical shift imaging

    DEFF Research Database (Denmark)

    Hanson, Lars Peter Grüner; Adalsteinsson, E; Pfefferbaum, A;

    2000-01-01

    Quantification of gray and white matter levels of spectroscopically visible metabolites can provide important insights into brain development and pathological conditions. Chemical shift imaging offers a gain in efficiency for estimation of global gray and white matter metabolite concentrations...

  4. Predicting Pt-195 NMR chemical shift using new relativistic all-electron basis set.

    Science.gov (United States)

    Paschoal, D; Guerra, C Fonseca; de Oliveira, M A L; Ramalho, T C; Dos Santos, H F

    2016-10-01

    Predicting NMR properties is a valuable tool to assist the experimentalists in the characterization of molecular structure. For heavy metals, such as Pt-195, only a few computational protocols are available. In the present contribution, all-electron Gaussian basis sets, suitable to calculate the Pt-195 NMR chemical shift, are presented for Pt and all elements commonly found as Pt-ligands. The new basis sets identified as NMR-DKH were partially contracted as a triple-zeta doubly polarized scheme with all coefficients obtained from a Douglas-Kroll-Hess (DKH) second-order scalar relativistic calculation. The Pt-195 chemical shift was predicted through empirical models fitted to reproduce experimental data for a set of 183 Pt(II) complexes which NMR sign ranges from -1000 to -6000 ppm. Furthermore, the models were validated using a new set of 75 Pt(II) complexes, not included in the descriptive set. The models were constructed using non-relativistic Hamiltonian at density functional theory (DFT-PBEPBE) level with NMR-DKH basis set for all atoms. For the best model, the mean absolute deviation (MAD) and the mean relative deviation (MRD) were 150 ppm and 6%, respectively, for the validation set (75 Pt-complexes) and 168 ppm (MAD) and 5% (MRD) for all 258 Pt(II) complexes. These results were comparable with relativistic DFT calculation, 200 ppm (MAD) and 6% (MRD). © 2016 Wiley Periodicals, Inc.

  5. Robust alignment of chromatograms by statistically analyzing the shifts matrix generated by moving window fast Fourier transform cross-correlation.

    Science.gov (United States)

    Zhang, Mingjing; Wen, Ming; Zhang, Zhi-Min; Lu, Hongmei; Liang, Yizeng; Zhan, Dejian

    2015-03-01

    Retention time shift is one of the most challenging problems during the preprocessing of massive chromatographic datasets. Here, an improved version of the moving window fast Fourier transform cross-correlation algorithm is presented to perform nonlinear and robust alignment of chromatograms by analyzing the shifts matrix generated by moving window procedure. The shifts matrix in retention time can be estimated by fast Fourier transform cross-correlation with a moving window procedure. The refined shift of each scan point can be obtained by calculating the mode of corresponding column of the shifts matrix. This version is simple, but more effective and robust than the previously published moving window fast Fourier transform cross-correlation method. It can handle nonlinear retention time shift robustly if proper window size has been selected. The window size is the only one parameter needed to adjust and optimize. The properties of the proposed method are investigated by comparison with the previous moving window fast Fourier transform cross-correlation and recursive alignment by fast Fourier transform using chromatographic datasets. The pattern recognition results of a gas chromatography mass spectrometry dataset of metabolic syndrome can be improved significantly after preprocessing by this method. Furthermore, the proposed method is available as an open source package at https://github.com/zmzhang/MWFFT2.

  6. Uncovering symmetry-breaking vector and reliability order for assigning secondary structures of proteins from atomic NMR chemical shifts in amino acids

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Wookyung [Pusan National University, Department of Physics, Center for Proteome Biophysics (Korea, Republic of); Lee, Woonghee; Lee, Weontae [Yonsei University, Department of Biochemistry, Structural Biochemistry and Molecular Biophysics Laboratory (Korea, Republic of); Kim, Suhkmann [Pusan National University, Department of Chemistry, Biochemistry and Bio-NMR Laboratory (Korea, Republic of); Chang, Iksoo, E-mail: iksoochang@pusan.ac.kr [Pusan National University, Department of Physics, Center for Proteome Biophysics (Korea, Republic of)

    2011-12-15

    Unravelling the complex correlation between chemical shifts of {sup 13}C{sup {alpha}}, {sup 13}C{sup {beta}}, {sup 13}C Prime , {sup 1}H{sup {alpha}}, {sup 15}N, {sup 1}H{sup N} atoms in amino acids of proteins from NMR experiment and local structural environments of amino acids facilitates the assignment of secondary structures of proteins. This is an important impetus for both determining the three-dimensional structure and understanding the biological function of proteins. The previous empirical correlation scores which relate chemical shifts of {sup 13}C{sup {alpha}}, {sup 13}C{sup {beta}}, {sup 13}C Prime , {sup 1}H{sup {alpha}}, {sup 15}N, {sup 1}H{sup N} atoms to secondary structures resulted in progresses toward assigning secondary structures of proteins. However, the physical-mathematical framework for these was elusive partly due to both the limited and orthogonal exploration of higher-dimensional chemical shifts of hetero-nucleus and the lack of physical-mathematical understanding underlying those correlation scores. Here we present a simple multi-dimensional hetero-nuclear chemical shift score function (MDHN-CSSF) which captures systematically the salient feature of such complex correlations without any references to a random coil state of proteins. We uncover the symmetry-breaking vector and its reliability order not only for distinguishing different secondary structures of proteins but also for capturing the delicate sensitivity interplayed among chemical shifts of {sup 13}C{sup {alpha}}, {sup 13}C{sup {beta}}, {sup 13}C Prime , {sup 1}H{sup {alpha}}, {sup 15}N, {sup 1}H{sup N} atoms simultaneously, which then provides a straightforward framework toward assigning secondary structures of proteins. MDHN-CSSF could correctly assign secondary structures of training (validating) proteins with the favourable (comparable) Q3 scores in comparison with those from the previous correlation scores. MDHN-CSSF provides a simple and robust strategy for the

  7. 125Te NMR chemical-shift trends in PbTe–GeTe and PbTe–SnTe alloys

    Energy Technology Data Exchange (ETDEWEB)

    Njegic, Bosiljka [Ames Laboratory; Levin, Evgenii M. [Ames Laboratory; Schmidt-Rohr, Klaus [Ames Laboratory

    2013-10-08

    Complex tellurides, such as doped PbTe, GeTe, and their alloys, are among the best thermoelectric materials. Knowledge of the change in 125Te NMR chemical shift due to bonding to dopant or “solute” atoms is useful for determination of phase composition, peak assignment, and analysis of local bonding. We have measured the 125Te NMR chemical shifts in PbTe-based alloys, Pb1-xGexTe and Pb1-xSnxTe, which have a rocksalt-like structure, and analyzed their trends. For low x, several peaks are resolved in the 22-kHz MAS 125Te NMR spectra. A simple linear trend in chemical shifts with the number of Pb neighbors is observed. No evidence of a proposed ferroelectric displacement of Ge atoms in a cubic PbTe matrix is detected at low Ge concentrations. The observed chemical shift trends are compared with the results of DFT calculations, which confirm the linear dependence on the composition of the first-neighbor shell. The data enable determination of the composition of various phases in multiphase telluride materials. They also provide estimates of the 125Te chemical shifts of GeTe and SnTe (+970 and +400±150 ppm, respectively, from PbTe), which are otherwise difficult to access due to Knight shifts of many hundreds of ppm in neat GeTe and SnTe.

  8. 125Te NMR chemical-shift trends in PbTe-GeTe and PbTe-SnTe alloys.

    Science.gov (United States)

    Njegic, B; Levin, E M; Schmidt-Rohr, K

    2013-01-01

    Complex tellurides, such as doped PbTe, GeTe, and their alloys, are among the best thermoelectric materials. Knowledge of the change in (125)Te NMR chemical shift due to bonding to dopant or "solute" atoms is useful for determination of phase composition, peak assignment, and analysis of local bonding. We have measured the (125)Te NMR chemical shifts in PbTe-based alloys, Pb1-xGexTe and Pb1-xSnxTe, which have a rocksalt-like structure, and analyzed their trends. For low x, several peaks are resolved in the 22-kHz MAS (125)Te NMR spectra. A simple linear trend in chemical shifts with the number of Pb neighbors is observed. No evidence of a proposed ferroelectric displacement of Ge atoms in a cubic PbTe matrix is detected at low Ge concentrations. The observed chemical shift trends are compared with the results of DFT calculations, which confirm the linear dependence on the composition of the first-neighbor shell. The data enable determination of the composition of various phases in multiphase telluride materials. They also provide estimates of the (125)Te chemical shifts of GeTe and SnTe (+970 and +400±150 ppm, respectively, from PbTe), which are otherwise difficult to access due to Knight shifts of many hundreds of ppm in neat GeTe and SnTe.

  9. Liver fat quantification: Comparison of dual-echo and triple-echo chemical shift MRI to MR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Satkunasingham, Janakan; Besa, Cecilia [Department of Radiology, Body MRI, Icahn School of Medicine at Mount Sinai, One Gustave Levy Place, New York, NY 10029 (United States); Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, One Gustave Levy Place, New York, NY 10029 (United States); Bane, Octavia [Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, One Gustave Levy Place, New York, NY 10029 (United States); Shah, Ami [Department of Radiology, Body MRI, Icahn School of Medicine at Mount Sinai, One Gustave Levy Place, New York, NY 10029 (United States); Oliveira, André de; Gilson, Wesley D.; Kannengiesser, Stephan [Siemens AG, Healthcare Sector, Erlangen (Germany); Taouli, Bachir, E-mail: bachir.taouli@mountsinai.org [Department of Radiology, Body MRI, Icahn School of Medicine at Mount Sinai, One Gustave Levy Place, New York, NY 10029 (United States); Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, One Gustave Levy Place, New York, NY 10029 (United States)

    2015-08-15

    Highlights: • We present a large cohort of patients who underwent dual and triple echo chemical shift imaging against multi-echo T{sub 2} corrected MR spectroscopy (MRS) for liver fat quantification. • Our data suggests that a triple-echo sequence is highly accurate for detection of liver fat, even in the presence of T{sub 2}{sup *} shortening, with minor discrepancies when compared with the advanced fat quantification method. - Abstract: Purpose: To assess the diagnostic value of MRI using dual-echo (2PD) and triple-echo (3PD) chemical shift imaging for liver fat quantification against multi-echo T{sub 2} corrected MR spectroscopy (MRS) used as the reference standard, and examine the effect of T{sub 2}{sup *} imaging on accuracy of MRI for fat quantification. Materials and methods: Patients who underwent 1.5 T liver MRI that incorporated 2PD, 3PD, multi-echo T{sub 2}{sup *} and MRS were included in this IRB approved prospective study. Regions of interest were placed in the liver to measure fat fraction (FF) with 2PD and 3PD and compared with MRS-FF. A random subset of 25 patients with a wide range of MRS-FF was analyzed with an advanced FF calculation method, to prove concordance with the 3PD. The statistical analysis included correlation stratified according to T{sub 2}{sup *}, Bland-Altman analysis, and calculation of diagnostic accuracy for detection of MRS-FF > 6.25%. Results: 220 MRI studies were identified in 217 patients (mean BMI 28.0 ± 5.6). 57/217 (26.2%) patients demonstrated liver steatosis (MRS-FF > 6.25%). Bland-Altman analysis revealed strong agreement between 3PD and MRS (mean ± 1.96 SD: −0.5% ± 4.6%) and weaker agreement between 2PD and MRS (4.7% ± 16.0%). Sensitivity of 3PD for diagnosing FF> 6.25% was higher than that of 2PD. 3PD-FF showed minor discrepancies (coefficient of variation <10%) from FF measured with the advanced method. Conclusion: Our large series study validates the use of 3PD chemical shift sequence for detection of

  10. In Situ Correlated Molecular Imaging of Chemically Communicating Microbial Communities

    Energy Technology Data Exchange (ETDEWEB)

    Bohn, Paul W. [Univ. of Notre Dame, IN (United States); Shrout, J. D. [Univ. of Notre Dame, IN (United States); Sweedler, J. V. [Univ. of Illinois, Urbana-Champaign, IL (United States); Farrand, S. [Univ. of Illinois, Urbana-Champaign, IL (United States)

    2016-01-25

    This document constitutes the final technical report for DE-SC0006642, In Situ Correlated Molecular Imaging of Chemically Communicating Microbial Communities, a project carried out collaboratively by investigators at Notre Dame and UIUC. The work carried out under DOE support in this project produced advances in two areas: development of new highly sophisticated correlated imaging approaches and the application of these new tools to the growth and differentiation of microbial communities under a variety of environmental conditions. A significant effort involved the creation of technical enhancements and sampling approaches to allow us to advance heterocorrelated mass spectrometry imaging (MSI) and correlated Raman microscopy (CRM) from bacterial cultures and biofilms. We then exploited these measurement advances in heterocorrelated MS/CRM imaging to determine relationship of signaling molecules and excreted signaling molecules produced by P. aeruginosa to conditions relevant to the rhizosphere. In particular, we: (1) developed a laboratory testbed mimic for the rhizosphere to enable microbial growth on slides under controlled conditions; (2) integrated specific measurements of (a) rhamnolipids, (b) quinolone/quinolones, and (c) phenazines specific to P. aeruginosa; and (3) utilized the imaging tools to probe how messenger secretion, quorum sensing and swarming behavior are correlated with behavior.

  11. Reassigning the Structures of Natural Products Using NMR Chemical Shifts Computed with Quantum Mechanics: A Laboratory Exercise

    Science.gov (United States)

    Palazzo, Teresa A.; Truong, Tiana T.; Wong, Shirley M. T.; Mack, Emma T.; Lodewyk, Michael W.; Harrison, Jason G.; Gamage, R. Alan; Siegel, Justin B.; Kurth, Mark J.; Tantillo, Dean J.

    2015-01-01

    An applied computational chemistry laboratory exercise is described in which students use modern quantum chemical calculations of chemical shifts to assign the structure of a recently isolated natural product. A pre/post assessment was used to measure student learning gains and verify that students demonstrated proficiency of key learning…

  12. Predicting the redox state and secondary structure of cysteine residues using multi-dimensional classification analysis of NMR chemical shifts.

    Science.gov (United States)

    Wang, Ching-Cheng; Lai, Wen-Chung; Chuang, Woei-Jer

    2016-09-01

    A tool for predicting the redox state and secondary structure of cysteine residues using multi-dimensional analyses of different combinations of nuclear magnetic resonance (NMR) chemical shifts has been developed. A data set of cysteine [Formula: see text], (13)C(α), (13)C(β), (1)H(α), (1)H(N), and (15)N(H) chemical shifts was created, classified according to redox state and secondary structure, using a library of 540 re-referenced BioMagResBank (BMRB) entries. Multi-dimensional analyses of three, four, five, and six chemical shifts were used to derive rules for predicting the structural states of cysteine residues. The results from 60 BMRB entries containing 122 cysteines showed that four-dimensional analysis of the C(α), C(β), H(α), and N(H) chemical shifts had the highest prediction accuracy of 100 and 95.9 % for the redox state and secondary structure, respectively. The prediction of secondary structure using 3D, 5D, and 6D analyses had the accuracy of ~90 %, suggesting that H(N) and [Formula: see text] chemical shifts may be noisy and made the discrimination worse. A web server (6DCSi) was established to enable users to submit NMR chemical shifts, either in BMRB or key-in formats, for prediction. 6DCSi displays predictions using sets of 3, 4, 5, and 6 chemical shifts, which shows their consistency and allows users to draw their own conclusions. This web-based tool can be used to rapidly obtain structural information regarding cysteine residues directly from experimental NMR data.

  13. The interplay between transient a-helix formation and side chain rotamer distributions in disordered proteins probed by methyl chemical shifts

    DEFF Research Database (Denmark)

    Kjærgaard, Magnus; Iesmantavicius, Vytautas; Poulsen, Flemming M

    2011-01-01

    and retinoid receptors (ACTR). We find that small differences in the methyl carbon chemical shifts due to the ¿-gauche effect may provide information about the side chain rotamer distributions. However, the effects of neighboring residues on the methyl group chemical shifts obscure the direct observation...... of ¿-gauche effect. To overcome this, we reference the chemical shifts to those in a more disordered state resulting in residue specific random coil chemical shifts. The (13)C secondary chemical shifts of the methyl groups of valine, leucine, and isoleucine show sequence specific effects, which allow...

  14. Ab Initio Calculations of Deuterium Isotope Effects on Chemical Shifts of Salt-Bridged Lysines

    DEFF Research Database (Denmark)

    Ullah, Saif; Ishimoto, Takayoshi; Williamson, Mike P.;

    2011-01-01

    Deuterium isotope effects measure the change in chemical shift on substitution of a proton by deuterium. They have been calculated by direct treatment of the H/D nuclear quantum effect using a multicomponent ab initio molecular orbital method based on a non-Born−Oppenheimer approximation....... This method enables the determination of both the electronic and the protonic (deuteronic) wave functions simultaneously and can directly calculate the geometrical difference induced by H/D isotope effects. The calculations show that the one-bond deuterium isotope effects on 15N nuclear shielding, 1Δ15N......(D), in ammonium and amines decrease as a counterion or water molecule moves closer to the nitrogen. 1Δ15N(D) and 2Δ1H(D) of the NH3+ groups of lysine residues in the B1 domain of protein G have been calculated using truncated side chains and also determined experimentally by NMR. Comparisons show...

  15. Alpha spindles as neurophysiological correlates indicating attentional shift in a simulated driving task.

    Science.gov (United States)

    Sonnleitner, Andreas; Simon, Michael; Kincses, Wilhelm E; Buchner, Axel; Schrauf, Michael

    2012-01-01

    The intention of this paper is to describe neurophysiological correlates of driver distraction with highly robust parameters in the EEG (i.e. alpha spindles). In a simulated driving task with two different secondary tasks (i.e. visuomotor, auditory), N=28 participants had to perform full stop brakes reacting to appearing stop signs and red traffic lights. Alpha spindle rate was significantly higher during an auditory secondary task and significantly lower during a visuomotor secondary task as compared to driving only. Alpha spindle duration was significantly shortened during a visuomotor secondary task. The results are consistent with the assumption that alpha spindles indicate active inhibition of visual information processing. Effects on the alpha spindles while performing secondary tasks on top of the driving task indicate attentional shift according to the task modality. As compared to alpha band power, both the measures of alpha spindle rate and alpha spindle duration were less vulnerable to artifacts and the effect sizes were larger, allowing for a more accurate description of the current driver state.

  16. Developmental instability and right shift theory hypotheses concerning correlates of familial sinistrality: negative findings.

    Science.gov (United States)

    McKeever, W F; Cerone, L J; Chase-Carmichael, C

    2000-04-01

    Both the right shift (Annett, 1985) and developmental instability (Yeo & Gangestad, 1993) theories of handedness predict that familial sinistrality (FS) should relate to hand skill asymmetries (HSA) on peg-moving tasks. Annett also hypothesises that both HSA and a procedure she derived for classifying individuals according to the pattern of their hand preferences for different manual activities can index the genotypes posited in her theory, i.e. she believes these variables are highly correlated. These hypotheses were tested in a sample of 280 dextral college students. Results failed to support the finding of Gangestad and Yeo (1994) that subjects showing greater hand skill asymmetry deviations from typical asymmetry had a greater probability of having a left-handed parent. There was also no support for Annett's finding that greater dextrality, as defined by her hand preference classification system, was negatively associated with familial sinistrality. Additionally, the relationship between HSA and Annett's hand preference classes was found to be exceedingly weak, contrary to Annett's theorising. These and other failures to find highly replicable differences between FS- and FS+ dextrals cast doubt on the validity of genetic or partial-genetic theories of handedness that posit a ''penetrance'' of a recessive non-dextrality-favouring gene that causes presumed dextral heterozygotic persons to differ from presumed homozygotic dominant persons in cognitive or manual skills.

  17. Study of wavelength-shifting chemicals for use in large-scale water Cherenkov detectors

    CERN Document Server

    Sweany, M; Dazeley, S; Dunmore, J; Felde, J; Svoboda, R; Tripathi, M

    2011-01-01

    Cherenkov detectors employ various methods to maximize light collection at the photomultiplier tubes (PMTs). These generally involve the use of highly reflective materials lining the interior of the detector, reflective materials around the PMTs, or wavelength-shifting sheets around the PMTs. Recently, the use of water-soluble wavelength-shifters has been explored to increase the measurable light yield of Cherenkov radiation in water. These wave-shifting chemicals are capable of absorbing light in the ultravoilet and re-emitting the light in a range detectable by PMTs. Using a 250 L water Cherenkov detector, we have characterized the increase in light yield from three compounds in water: 4-Methylumbelliferone, Carbostyril-124, and Amino-G Salt. We report the gain in PMT response at a concentration of 1 ppm as: 1.88 $\\pm$ 0.02 for 4-Methylumbelliferone, stable to within 0.5% over 50 days, 1.37 $\\pm$ 0.03 for Carbostyril-124, and 1.20 $\\pm$ 0.02 for Amino-G Salt. The response of 4-Methylumbelliferone was modele...

  18. Handling the influence of chemical shift in amplitude-modulated heteronuclear dipolar recoupling solid-state NMR

    Science.gov (United States)

    Basse, Kristoffer; Shankar, Ravi; Bjerring, Morten; Vosegaard, Thomas; Nielsen, Niels Chr.; Nielsen, Anders B.

    2016-09-01

    We present a theoretical analysis of the influence of chemical shifts on amplitude-modulated heteronuclear dipolar recoupling experiments in solid-state NMR spectroscopy. The method is demonstrated using the Rotor Echo Short Pulse IRrAdiaTION mediated Cross-Polarization (RESPIRATIONCP) experiment as an example. By going into the pulse sequence rf interaction frame and employing a quintuple-mode operator-based Floquet approach, we describe how chemical shift offset and anisotropic chemical shift affect the efficiency of heteronuclear polarization transfer. In this description, it becomes transparent that the main attribute leading to non-ideal performance is a fictitious field along the rf field axis, which is generated from second-order cross terms arising mainly between chemical shift tensors and themselves. This insight is useful for the development of improved recoupling experiments. We discuss the validity of this approach and present quaternion calculations to determine the effective resonance conditions in a combined rf field and chemical shift offset interaction frame transformation. Based on this, we derive a broad-banded version of the RESPIRATIONCP experiment. The new sequence is experimentally verified using SNNFGAILSS amyloid fibrils where simultaneous 15N → 13CO and 15N → 13Cα coherence transfer is demonstrated on high-field NMR instrumentation, requiring great offset stability.

  19. 50 years anniversary of the discovery of the core level chemical shifts. The early years of photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Mårtensson, Nils [Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala (Sweden); Sokolowski, Evelyn [Tvär-Ramsdal 1, 611 99 Tystberga (Sweden); Svensson, Svante, E-mail: Svante.Svensson@fysik.uu.se [Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala (Sweden)

    2014-03-01

    Highlights: • 50 years since the discovery of t the core level chemical shift. • The pioneering years of ESCA. • A critical review of the first core electron chemical shift results. - Abstract: The pioneering years of photoelectron spectroscopy in Uppsala are discussed, especially the work leading to the discovery of the core level chemical shifts. At a very early stage of the project, the pioneering group observed what they described as evidence for chemical shifts in the core level binding energies. However, it can now be seen that the initial observations to a large extent was due to charging of the samples. It is interesting to note that the decisive experiment was realized, not as a result of a systematic study, but was obtained with a large element of serendipity. Only when a chemical binding energy shift was observed between two S2p electron lines in the same molecule, the results were accepted internationally, and the fascinating expansion of modern core level photoelectron spectroscopy could start.

  20. Correlation Between Chemical Element Contents in Tree Rings and Soils

    Institute of Scientific and Technical Information of China (English)

    QIANJUN-LONG; KESHAN-ZHE; 等

    1993-01-01

    The annual growth rings of ten trees and the soils near the tree roots were sampled from the mining ares of lead-and zinc-dominant metals in the Xixia Mountain,Nanjing,for the determination of chemical element contents.The study results showed that the elemental contents in the tree rings were correlated with those in the soils,i.e.,the elemental contents in the tree rings increased with those in the soils,even in the cases of different environments and different tree species.Therefore,a time-concentration sequence could be set up on the basis of determining the elemental contents in the successive annual growth rings of trees to qualitatively reflect the annual variations of relevant elements in the soils,and a time-concentration sequence of elemental contents in soils could also be established in terms of related model to reproduce the dynamic changes of the surroundings.

  1. Toward structural dynamics: protein motions viewed by chemical shift modulations and direct detection of C'N multiple-quantum relaxation.

    Science.gov (United States)

    Mori, Mirko; Kateb, Fatiha; Bodenhausen, Geoffrey; Piccioli, Mario; Abergel, Daniel

    2010-03-17

    Multiple quantum relaxation in proteins reveals unexpected relationships between correlated or anti-correlated conformational backbone dynamics in alpha-helices or beta-sheets. The contributions of conformational exchange to the relaxation rates of C'N coherences (i.e., double- and zero-quantum coherences involving backbone carbonyl (13)C' and neighboring amide (15)N nuclei) depend on the kinetics of slow exchange processes, as well as on the populations of the conformations and chemical shift differences of (13)C' and (15)N nuclei. The relaxation rates of C'N coherences, which reflect concerted fluctuations due to slow chemical shift modulations (CSMs), were determined by direct (13)C detection in diamagnetic and paramagnetic proteins. In well-folded proteins such as lanthanide-substituted calbindin (CaLnCb), copper,zinc superoxide dismutase (Cu,Zn SOD), and matrix metalloproteinase (MMP12), slow conformational exchange occurs along the entire backbone. Our observations demonstrate that relaxation rates of C'N coherences arising from slow backbone dynamics have positive signs (characteristic of correlated fluctuations) in beta-sheets and negative signs (characteristic of anti-correlated fluctuations) in alpha-helices. This extends the prospects of structure-dynamics relationships to slow time scales that are relevant for protein function and enzymatic activity.

  2. Chemical shift tensor determination using magnetically oriented microcrystal array (MOMA): 13C solid-state CP NMR without MAS

    Science.gov (United States)

    Kusumi, R.; Kimura, F.; Song, G.; Kimura, T.

    2012-10-01

    Chemical shift tensors for the carboxyl and methyl carbons of L-alanine crystals were determined using a magnetically oriented microcrystal array (MOMA) prepared from a microcrystalline powder sample of L-alanine. A MOMA is a single-crystal-like composite in which microcrystals are aligned three-dimensionally in a matrix resin. The single-crystal rotation method was applied to the MOMA to determine the principal values and axes of the chemical shift tensors. The result showed good agreement with the literature data for the single crystal of L-alanine. This demonstrates that the present technique is a powerful tool for determining the chemical shift tensor of a crystal from a microcrystal powder sample.

  3. Chemical shift assignments of zinc finger domain of methionine aminopeptidase 1 (MetAP1) from Homo sapiens.

    Science.gov (United States)

    Rachineni, Kavitha; Arya, Tarun; Singarapu, Kiran Kumar; Addlagatta, Anthony; Bharatam, Jagadeesh

    2015-10-01

    Methionine aminopeptidase Type I (MetAP1) cleaves the initiator methionine from about 70 % of all newly synthesized proteins in almost every living cell. Human MetAP1 is a two domain protein with a zinc finger on the N-terminus and a catalytic domain on the C-terminus. Here, we report the chemical shift assignments of the amino terminal zinc binding domain (ZBD) (1-83 residues) of the human MetAP1 derived by using advanced NMR spectroscopic methods. We were able to assign the chemical shifts of ZBD of MetAP1 nearly complete, which reveal two helical fragments involving residues P44-L49 (α1) and Q59-K82 (α2). The protein structure unfolds upon complex formation with the addition of 2 M excess EDTA, indicated by the appearance of amide resonances in the random coil chemical shift region of (15)NHSQC spectrum.

  4. Corrosion inhibitors: Correlation between chemical structure and efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Lukovits, I.; Koszto, T. [Hungarian Academy of Sciences (Hungary). Inst. of Chemistry

    1999-11-01

    Corrosion inhibition efficiencies of heterocyclic aromatic or partially saturated aromatic compounds (pyrimidines, benzothiazole derivatives, amino-acids containing an aromatic part, pyridines and quinolines) were correlated with quan chemical indices of the respective molecules. Inhibition efficiencies measured in acidic solutions containing 0.001 and 0.01 mol/L of the inhibitor, respectively, were collected. The quantum chemical calculations were done by using the simple Hueckel method. Comparison of inhibition efficiencies and the differences between energies of the highest occupied and the lowest unoccupied molecular orbitals {Delta} indicated that if {Delta} is lower than 1.3 (in beta units) then the compound will not be active, whereas if {Delta} > 1.3 beta, the compound may be efficient in 0.001 mole/L concentration. The critical value of {Delta} may be lower in solution with 0.01 mole/L inhibitor concentration. Although {Delta} alone is not sufficient to account for the variation in the experimental inhibition efficiencies, the present result indicates that compounds which may be easily excited will be inefficient inhibitors because they maybe altered or decomposed after the excitation takes place.

  5. Regional Differences in Muscle Energy Metabolism in Human Muscle by 31P-Chemical Shift Imaging.

    Science.gov (United States)

    Kime, Ryotaro; Kaneko, Yasuhisa; Hongo, Yoshinori; Ohno, Yusuke; Sakamoto, Ayumi; Katsumura, Toshihito

    2016-01-01

    Previous studies have reported significant region-dependent differences in the fiber-type composition of human skeletal muscle. It is therefore hypothesized that there is a difference between the deep and superficial parts of muscle energy metabolism during exercise. We hypothesized that the inorganic phosphate (Pi)/phosphocreatine (PCr) ratio of the superficial parts would be higher, compared with the deep parts, as the work rate increases, because the muscle fiber-type composition of the fast-type may be greater in the superficial parts compared with the deep parts. This study used two-dimensional 31Phosphorus Chemical Shift Imaging (31P-CSI) to detect differences between the deep and superficial parts of the human leg muscles during dynamic knee extension exercise. Six healthy men participated in this study (age 27±1 year, height 169.4±4.1 cm, weight 65.9±8.4 kg). The experiments were carried out with a 1.5-T superconducting magnet with a 5-in. diameter circular surface coil. The subjects performed dynamic one-legged knee extension exercise in the prone position, with the transmit-receive coil placed under the right quadriceps muscles in the magnet. The subjects pulled down an elastic rubber band attached to the ankle at a frequency of 0.25, 0.5 and 1 Hz for 320 s each. The intracellular pH (pHi) was calculated from the median chemical shift of the Pi peak relative to PCr. No significant difference in Pi/PCr was observed between the deep and the superficial parts of the quadriceps muscles at rest. The Pi/PCr of the superficial parts was not significantly increased with increasing work rate. Compared with the superficial areas, the Pi/PCr of the deep parts was significantly higher (p<0.05) at 1 Hz. The pHi showed no significant difference between the two parts. These results suggest that muscle oxidative metabolism is different between deep and superficial parts of quadriceps muscles during dynamic exercise.

  6. Efficient face recognition using local derivative pattern and shifted phase-encoded fringe-adjusted joint transform correlation

    Science.gov (United States)

    Biswas, Bikram K.; Alam, Mohammad S.; Chowdhury, Suparna

    2016-04-01

    An improved shifted phase-encoded fringe-adjusted joint transform correlation technique is proposed in this paper for face recognition which can accommodate the detrimental effects of noise, illumination, and other 3D distortions such as expression and rotation variations. This technique utilizes a third order local derivative pattern operator (LDP3) followed by a shifted phase-encoded fringe-adjusted joint transform correlation (SPFJTC) operation. The local derivative pattern operator ensures better facial feature extraction in a variable environment while the SPFJTC yields robust correlation output for the desired signals. The performance of the proposed method is determined by using the Yale Face Database, Yale Face Database B, and Georgia Institute of Technology Face Database. This technique has been found to yield better face recognition rate compared to alternate JTC based techniques.

  7. Electrophysiological correlates of preparation and implementation for different types of task shifts.

    Science.gov (United States)

    Hsieh, Shulan; Wu, Mengyao

    2011-11-14

    The ability to flexibly shift between tasks is central to cognitive control, but whether the same brain mechanisms mediate shifting across different tasks is unknown. In this study, we investigated whether variations in stimulus-dimensions or response-mapping might influence task switching in terms of its preparatory processes, as reflected in cue-locked event-related potentials (ERPs), and its implementation processes, as reflected in stimulus-locked ERPs. Participants judged pairs of digits as same or different in one of two conditions. In one condition, the task-relevant stimulus-dimension was either repeated or switched across trials while the response-mapping rule was kept constant. In the other condition, the task-relevant stimulus-dimension was kept constant while the response-mapping rule was repeated or switched across trials. The length of the preparatory interval was manipulated. Data revealed switch-related preparatory ERP components (including N2 and a late slow positivity) that were associated with both types of task shifting and an N400-like negativity that distinguished between the two types. Several switch-related implementation ERP components associated with both types of task shifting were found at posterior sites. Distinct frontal modulations of the N1, P2, and N2 were found to associate with the implementation of the response-mapping shift, whereas a slow positivity was associated with the implementation of the stimulus-dimension shift. Therefore, this study demonstrates that there are shared and distinct processes across different types of task shifting. Finally, because the same transition-cue was used for different task shifts, the distinct processes cannot be explained simply by differences in cue processing.

  8. Effects of Irritant Chemicals on Aedes aegypti Resting Behavior: Is There a Simple Shift to Untreated "Safe Sites"?

    Science.gov (United States)

    2011-07-26

    Effects of Irritant Chemicals on Aedes aegypti Resting Behavior: Is There a Simple Shift to Untreated ‘‘Safe Sites’’? Hortance Manda*, Luana M. Arce... aegypti to irritant and repellent chemicals that can be exploited to reduce man-vector contact. Maximum efficacy of interventions based on irritant...overall impact. Methods: Using a laboratory box assay, resting patterns of two population strains of female Ae. aegypti (THAI and PERU) were evaluated

  9. Characterization of mu s-ms dynamics of proteins using a combined analysis of N-15 NMR relaxation and chemical shift: Conformational exchange in plastocyanin induced by histidine protonations

    DEFF Research Database (Denmark)

    Hass, M. A. S.; Thuesen, Marianne Hallberg; Christensen, Hans Erik Mølager

    2004-01-01

    An approach is presented that allows a detailed, quantitative characterization of conformational exchange processes in proteins on the mus-ms time scale. The approach relies on a combined analysis of NMR relaxation rates and chemical shift changes and requires that the chemical shift...... variabilis (A.v. PCu) (Ma, L.; Hass, M. A. S.; Vierick, N.; Kristensen, S. M.; Ulstrup, J.; Led, J. J. Biochemistry 2003, 42, 320-330). The R-1 and R-2 relaxation rates of the backbone N-15 nuclei were measured at a series of pH and temperatures on an 15N labeled sample of A.v. PCu, and the 15 N chemical...... quantitatively by the correlation between the R-ex terms and the corresponding chemical shift differences of the exchanging species. By this approach, the R-ex terms of N-15 nuclei belonging to contiguous regions in the protein could be assigned to the same exchange process. Furthermore, the analysis...

  10. SUBSTITUENT CHEMICAL SHIFT (SCS) AND THE SEQUENCE STRUCTURE OF ETHYLENE-VINYL ALCOHOL COPOLYMERS

    Institute of Scientific and Technical Information of China (English)

    ZHOU Zinan; TIAN Wenjing; WU Shengrong; DAI Yingkun; FENG Zhiliu; SHEN Lianfang; YUAN Hanzhen

    1992-01-01

    Three ethylene-vinyl alcohol copolymers were studied by means of the substituent chemical shift(SCS) method. The SCS parameters of hydroxy (-OH)in two different solvents were obtained: in deuterium oxide/phenol (20/80 W/W ) the parameters are S1 = 42.77 ± 0.08ppm, S2 = 7.15 ±0.06 ppm,S3(s )=-4.08±0.02ppm, S3(t)=-3.09±0.20ppm,S4=0.48±0.03ppm, S5 =0.26±0.05ppm. In o-dichlorobenzen-d4 S1(s)=44.79±0.61ppm, S2=7.40±0.00ppm, S3 (s)=-4.51±0.17ppm, S3 (t)= -3.13± 0.00 ppm, S4 =0 . 63±0.04ppm, S5=0.36±0.00ppm. Simultaneously the 13CNMR spectra of EVA copolymers were assigned by using the SCS parameters obtained.

  11. Chemical Fingerprint of Dachaihu Granule and Its Chemical Correlation Between Raw Herbs.

    Science.gov (United States)

    Mao, Chunqin; Zhou, Yaping; Ji, De; Tan, Xuanzhong; Tao, Yi; Zang, Wenyi; Lu, Tulin

    2017-04-01

    To develop a method to overall evaluate the quality of Dachaihu Granule (DCHG), high-performance liquid chromatography coupled with diode array detector was used to establish chemical fingerprint of DCHG. The correlation between the formula and its raw herbs was also evaluated. According to the retention time of standard components, chemical fingerprint of DCHG was developed and a total of 21 constituents were characterized. The separation was performed on a Kromasil C18 column (250 mm × 4.6 mm i.d. with 5.0 μm particle size) with a linear gradient elution of acetonitrile and water with 0.05% phosphoric acid. Precision, stability and repeatability of the method were validated. The developed method was subsequently applied to evaluate 15 batches of DCHG using similarity analysis, principal component analysis and partial least squares discriminate analysis.

  12. Analysis of {sup 13}C{sup {alpha}} and {sup 13}C{sup {beta}} chemical shifts of cysteine and cystine residues in proteins: a quantum chemical approach

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Osvaldo A.; Villegas, Myriam E.; Vila, Jorge A. [Universidad Nacional de San Luis, Instituto de Matematica Aplicada San Luis (Argentina); Scheraga, Harold A., E-mail: has5@cornell.ed [Cornell University, Baker Laboratory of Chemistry and Chemical Biology (United States)

    2010-03-15

    Cysteines possess a unique property among the 20 naturally occurring amino acids: it can be present in proteins in either the reduced or oxidized form, and can regulate the activity of some proteins. Consequently, to augment our previous treatment of the other types of residues, the {sup 13}C{sup {alpha}} and {sup 13}C{sup {beta}} chemical shifts of 837 cysteines in disulfide-bonded cystine from a set of seven non-redundant proteins, determined by X-ray crystallography and NMR spectroscopy, were computed at the DFT level of theory. Our results indicate that the errors between observed and computed {sup 13}C{sup {alpha}} chemical shifts of such oxidized cysteines can be attributed to several effects such as: (a) the quality of the NMR-determined models, as evaluated by the conformational-average (ca) rmsd value; (b) the existence of high B-factor or crystal-packing effects for the X-ray-determined structures; (c) the dynamics of the disulfide bonds in solution; and (d) the differences in the experimental conditions under which the observed {sup 13}C{sup {alpha}} chemical shifts and the protein models were determined by either X-ray crystallography or NMR-spectroscopy. These quantum-chemical-based calculations indicate the existence of two, almost non-overlapped, basins for the oxidized and reduced -SH {sup 13}C{sup {beta}}, but not for the {sup 13}C{sup {alpha}}, chemical shifts, in good agreement with the observation of 375 {sup 13}C{sup {alpha}} and 337 {sup 13}C{sup {beta}} resonances from 132 proteins by Sharma and Rajarathnam (2000). Overall, our results indicate that explicit consideration of the disulfide bonds is a necessary condition for an accurate prediction of {sup 13}C{sup {alpha}} and {sup 13}C{sup {beta}} chemical shifts of cysteines in cystines.

  13. Analysis of the contributions of ring current and electric field effects to the chemical shifts of RNA bases.

    Science.gov (United States)

    Sahakyan, Aleksandr B; Vendruscolo, Michele

    2013-02-21

    Ring current and electric field effects can considerably influence NMR chemical shifts in biomolecules. Understanding such effects is particularly important for the development of accurate mappings between chemical shifts and the structures of nucleic acids. In this work, we first analyzed the Pople and the Haigh-Mallion models in terms of their ability to describe nitrogen base conjugated ring effects. We then created a database (DiBaseRNA) of three-dimensional arrangements of RNA base pairs from X-ray structures, calculated the corresponding chemical shifts via a hybrid density functional theory approach and used the results to parametrize the ring current and electric field effects in RNA bases. Next, we studied the coupling of the electric field and ring current effects for different inter-ring arrangements found in RNA bases using linear model fitting, with joint electric field and ring current, as well as only electric field and only ring current approximations. Taken together, our results provide a characterization of the interdependence of ring current and electric field geometric factors, which is shown to be especially important for the chemical shifts of non-hydrogen atoms in RNA bases.

  14. Elucidation of the substitution pattern of 9,10-anthraquinones through the chemical shifts of peri-hydroxyl protons

    DEFF Research Database (Denmark)

    Schripsema, Jan; Danigno, Denise

    1996-01-01

    In 9,10-anthraquinones the chemical shift of a peri-hydroxyl proton is affected by the substituents in the other benzenoid ring. These effects are additive. They are useful for the determination of substitution patterns and have been used to revise the structures of six previously reported anthra...

  15. The local order of supercooled water in solution with LiCl studied by NMR proton chemical shift

    Science.gov (United States)

    Corsaro, C.; Mallamace, D.; Vasi, S.; Cicero, N.; Dugo, G.; Mallamace, F.

    2016-05-01

    We study by means of Nuclear Magnetic Resonance (NMR) spectroscopy the local order of water molecules in solution with lithium chloride at eutectic concentration. In particular, by measuring the proton chemical shift as a function of the temperature in the interval 203{ K}Widom line for water supporting the liquid-liquid transition hypothesis.

  16. The correlation of blue shift of photoluminescence and morphology of silicon nanoporous

    Science.gov (United States)

    Al-Jumaili, Batool E. B.; Talib, Zainal A.; Josephine L., Y.; Paiman, Suriati B.; Ahmed, Naser M.; Al-Jumaily, Abdulmajeed H. J.; Ramizy, Asmiet; Abdulateef, Sinan A.; Muh'd, Ibrahim B.; Mofdal, Manahil E. E.

    2016-07-01

    Porous silicon with diameters ranging from 6.41 to 7.12 nm were synthesized via electrochemical etching by varied anodization current density in ethanoic solutions containing aqueous hydrofluoric acid up to 65mA/cm2.The luminescence properties of the nanoporous at room temperature were analyzed via photoluminescence spectroscopy. Photoluminescence PL spectra exhibit a broad emission band in the range of 360-700 nm photon energy. The PL spectrum has a blue shift in varied anodization current density; the blue shift incremented as the existing of anodization although the intensity decreased. The current blue shift is owning to alteration of silicon nanocrystal structure at the superficies. The superficial morphology of the PS layers consists of unified and orderly distribution of nanocrystalline Si structures, have high porosity around (93.75%) and high thickness 39.52 µm.

  17. Female sea lamprey shift orientation toward a conspecific chemical cue to escape a sensory trap

    Science.gov (United States)

    Brant, Cory O.; Johnson, Nicholas; Li, Ke; Buchinger, Tyler J.; Li, Weiming

    2016-01-01

    The sensory trap model of signal evolution hypothesizes that signalers adapt to exploit a cue used by the receiver in another context. Although exploitation of receiver biases can result in conflict between the sexes, deceptive signaling systems that are mutually beneficial drive the evolution of stable communication systems. However, female responses in the nonsexual and sexual contexts may become uncoupled if costs are associated with exhibiting a similar response to a trait in both contexts. Male sea lamprey (Petromyzon marinus) signal with a mating pheromone, 3-keto petromyzonol sulfate (3kPZS), which may be a match to a juvenile cue used by females during migration. Upstream movement of migratory lampreys is partially guided by 3kPZS, but females only move toward 3kPZS with proximal accuracy during spawning. Here, we use in-stream behavioral assays paired with gonad histology to document the transition of female preference for juvenile- and male-released 3kPZS that coincides with the functional shift of 3kPZS as a migratory cue to a mating pheromone. Females became increasingly biased toward the source of synthesized 3kPZS as their maturation progressed into the reproductive phase, at which point, a preference for juvenile odor (also containing 3kPZS naturally) ceased to exist. Uncoupling of female responses during migration and spawning makes the 3kPZS communication system a reliable means of synchronizing mate search. The present study offers a rare example of a transition in female responses to a chemical cue between nonsexual and sexual contexts, provides insights into the origins of stable communication signaling systems.

  18. Liver steatosis (LS) evaluated through chemical-shift magnetic resonance imaging liver enzymes in morbid obesity; effect of weight loss obtained with intragastric balloon gastric banding.

    Science.gov (United States)

    Folini, Laura; Veronelli, Annamaria; Benetti, Alberto; Pozzato, Carlo; Cappelletti, Marco; Masci, Enzo; Micheletto, Giancarlo; Pontiroli, Antonio E

    2014-01-01

    The aim of this study was to evaluate in morbid obesity clinical and metabolic effects related to weight loss on liver steatosis (LS), measured through chemical-shift magnetic resonance imaging (MRI) and liver enzymes. Forty obese subjects (8 M/32 W; BMI 42.8 ± 7.12 kg/m(2), mean ± SD) were evaluated for LS through ultrasound (US-LS), chemical-shift MRI (MRI-LS), liver enzymes [aspartate aminotransferase (AST), alanine aminotransferase (ALT), γ-glutamyltransferase (GGT), alkaline phosphatase (ALP)], anthropometric parameters [weight, BMI, waist circumference (WC)], lipids, insulin, insulin resistance (HOMA-IR), glycated hemoglobin (HbA1c), oral glucose tolerance test, and body composition [fat mass (FM) and fat-free mass (FFM) at bio-impedance analysis (BIA)]. Anthropometric measures, MRI-LS, BIA, and biochemical parameters were reevaluated 6 months later in 18 subjects undergoing restrictive bariatric approach, i.e., intragastric balloon (BIB, n = 13) or gastric banding (LAGB, n = 5), and in 13 subjects receiving hypocaloric diet. At baseline, US-LS correlates only with MRI-LS, and the latter correlates with ALT, AST, and GGT. After 6 months, subjects undergoing BIB or LAGB had significant changes of BMI, weight, WC, ALT, AST, GGT, ALP, HbA1c, insulin, HOMA-IR, FM, FFM, and MRI-LS. Diet-treated obese subjects had no significant change of any parameter under study; change of BMI, fat mass, and fat-free mass was significantly greater in LAGB/BIB subjects than in diet-treated subjects. Change of MRI-LS showed a significant correlation with changes in weight, BMI, WC, GGT, ALP, and basal MRI-LS. Significant weight loss after BIB or LAGB is associated with decrease in chemical-shift MRI-LS and with reduction in liver enzymes; chemical-shift MRI and liver enzymes allow monitoring of LS in follow-up studies.

  19. Brazilian Propolis: Correlation between Chemical Composition and Antimicrobial Activity

    Directory of Open Access Journals (Sweden)

    Kelly Salomão

    2008-01-01

    Full Text Available The chemical composition of ethanol extracts from samples of Brazilian propolis (EEPs determined by HPLC and their activity against Trypanosoma cruzi, Staphylococcus aureus, Streptococcus pneumoniae, Klebisiella pneumoniae, Candida albicans, Sporothrix schenckii and Paracoccidioides brasiliensis were determined. Based on the predominant botanical origin in the region of samples' collection, the 10 extracts were separated into three groups: A (B. dracunculifolia + Auraucaria spp, B (B. dracunculifolia and C (Araucaria spp. Analysis by the multiple regression of all the extracts together showed a positive correlation, higher concentrations leading to higher biological effect, of S. aureus with p-coumaric acid (PCUM and 3-(4-hydroxy-3-(oxo-butenyl-phenylacrylic acid (DHCA1 and of trypomastigotes of T. cruzi with 3,5-diprenyl-4-hydroxycinnamic acid derivative 4 (DHCA4 and 2,2-dimethyl-6-carboxyethenyl-2H-1-benzopyran (DCBEN. When the same approach was employed for each group, due to the small number of observations, the statistical test gave unreliable results. However, an overall analysis revealed for group A an association of S. aureus with caffeic acid (CAF and dicaffeoylquinic acid 3 (CAFQ3, of S. pneumoniae with CAFQ3 and monocaffeoylquinic acid 2 (CAFQ2 and of T. cruzi also with CAFQ3. For group B, a higher activity against S. pneumoniae was associated DCBEN and for T. cruzi with CAF. For group C no association was observed between the anitmicrobial effect and any component of the extracts. The present study reinforces the relevance of PCUM and derivatives, especially prenylated ones and also of caffeolyquinic acids, on the biological activity of Brazilian propolis.

  20. The shift from a response strategy to object-in-place strategy during learning is accompanied by a matching shift in neural firing correlates in the hippocampus.

    Science.gov (United States)

    Lee, Inah; Kim, Jangjin

    2010-08-01

    Hippocampal-dependent tasks often involve specific associations among stimuli (including egocentric information), and such tasks are therefore prone to interference from irrelevant task strategies before a correct strategy is found. Using an object-place paired-associate task, we investigated changes in neural firing patterns in the hippocampus in association with a shift in strategy during learning. We used an object-place paired-associate task in which a pair of objects was presented in two different arms of a radial maze. Each object was associated with reward only in one of the arms, thus requiring the rats to consider both object identity and its location in the maze. Hippocampal neurons recorded in CA1 displayed a dynamic transition in their firing patterns during the acquisition of the task across days, and this corresponded to a shift in strategy manifested in behavioral data. Specifically, before the rats learned the task, they chose an object that maintained a particular egocentric relationship with their body (response strategy) irrespective of the object identity. However, as the animal acquired the task, it chose an object according to both its identity and the associated location in the maze (object-in-place strategy). We report that CA1 neurons in the hippocampus changed their prospective firing correlates according to the dominant strategy (i.e., response versus object-in-place strategy) employed at a given stage of learning. The results suggest that neural firing pattern in the hippocampus is heavily influenced by the task demand hypothesized by the animal and the firing pattern changes flexibly as the perceived task demand changes.

  1. On the Correlation between the Blue Shift of Hydrogen Bonding and the Proton Donor-Proton Acceptor Distance

    Institute of Scientific and Technical Information of China (English)

    WANG,Jin-Ti(王金姼); FENG,Yong(封勇); LIU,Lei(刘磊); LI,Xiao-Song(李晓松); GUO,Qing-Xiang(郭庆祥)

    2004-01-01

    It is demonstrated that in all types of hydrogen bonds (X-H…Y) there is a balance between the long-range attractive orbital interactions and short-range Pauli/nucleus repulsions. When the proton acceptor approaches the proton donor from distance, the hydrogen bonding energy becomes more negative at relatively large distance, goes through a minimum, and then starts to become less negative when the short-range repulsive forces come into effect.Meanwhile, the X-H bond length increases at relatively large distances, goes through a maximum and starts to shorten when the short-range repulsive forces come into effect. Whether the hydrogen bond is red or blue shifted is dictated by the energy minimum position. If at the energy minimum position the X-H bond length is shorter than that for the free monomer, the hydrogen bond is blue shifted and vice versa. Further studies demonstrate that the recent report about the correlation of C-H bond lengths with proton donor-acceptor distance in F3C-H…OH2 and F3C-H…Cl- is not fully correct because the authors conducted an inappropriate comparison. Furthermore, it is shown for the first time that the Pauli/nucleus repulsion theory is applicable to the blue-shifted hydrogen bonds in the X-H…π complexes and the blue-shifted lithium bonds in the X-Li…Y complexes.

  2. Cuticular hydrocarbon divergence in the jewel wasp Nasonia : evolutionary shifts in chemical communication channels?

    NARCIS (Netherlands)

    Buellesbach, J.; Gadau, J.; Beukeboom, L. W.; Echinger, F.; Raychoudhury, R.; Werren, J. H.; Schmitt, T.

    2013-01-01

    The evolution and maintenance of intraspecific communication channels constitute a key feature of chemical signalling and sexual communication. However, how divergent chemical communication channels evolve while maintaining their integrity for both sender and receiver is poorly understood. In this s

  3. Computer programming for nucleic acid studies. II. Total chemical shifts calculation of all protons of double-stranded helices.

    Science.gov (United States)

    Giessner-Prettre, C; Ribas Prado, F; Pullman, B; Kan, L; Kast, J R; Ts'o, P O

    1981-01-01

    A FORTRAN computer program called SHIFTS is described. Through SHIFTS, one can calculate the NMR chemical shifts of the proton resonances of single and double-stranded nucleic acids of known sequences and of predetermined conformations. The program can handle RNA and DNA for an arbitrary sequence of a set of 4 out of the 6 base types A,U,G,C,I and T. Data files for the geometrical parameters are available for A-, A'-, B-, D- and S-conformations. The positions of all the atoms are calculated using a modified version of the SEQ program [1]. Then, based on this defined geometry three chemical shift effects exerted by the atoms of the neighboring nucleotides on the protons of each monomeric unit are calculated separately: the ring current shielding effect: the local atomic magnetic susceptibility effect (including both diamagnetic and paramagnetic terms); and the polarization or electric field effect. Results of the program are compared with experimental results for a gamma (ApApGpCpUpU) 2 helical duplex and with calculated results on this same helix based on model building of A'-form and B-form and on graphical procedure for evaluating the ring current effects.

  4. Towards the versatile DFT and MP2 computational schemes for 31P NMR chemical shifts taking into account relativistic corrections.

    Science.gov (United States)

    Fedorov, Sergey V; Rusakov, Yury Yu; Krivdin, Leonid B

    2014-11-01

    The main factors affecting the accuracy and computational cost of the calculation of (31)P NMR chemical shifts in the representative series of organophosphorous compounds are examined at the density functional theory (DFT) and second-order Møller-Plesset perturbation theory (MP2) levels. At the DFT level, the best functionals for the calculation of (31)P NMR chemical shifts are those of Keal and Tozer, KT2 and KT3. Both at the DFT and MP2 levels, the most reliable basis sets are those of Jensen, pcS-2 or larger, and those of Pople, 6-311G(d,p) or larger. The reliable basis sets of Dunning's family are those of at least penta-zeta quality that precludes their practical consideration. An encouraging finding is that basically, the locally dense basis set approach resulting in a dramatic decrease in computational cost is justified in the calculation of (31)P NMR chemical shifts within the 1-2-ppm error. Relativistic corrections to (31)P NMR absolute shielding constants are of major importance reaching about 20-30 ppm (ca 7%) improving (not worsening!) the agreement of calculation with experiment. Further better agreement with the experiment by 1-2 ppm can be obtained by taking into account solvent effects within the integral equation formalism polarizable continuum model solvation scheme. We recommend the GIAO-DFT-KT2/pcS-3//pcS-2 scheme with relativistic corrections and solvent effects taken into account as the most versatile computational scheme for the calculation of (31)P NMR chemical shifts characterized by a mean absolute error of ca 9 ppm in the range of 550 ppm.

  5. Chemical shift of Mn and Cr K-edges in X-ray absorption spectroscopy with synchrotron radiation

    Indian Academy of Sciences (India)

    D Joseph; A K Yadav; S N Jha; D Bhattacharyya

    2013-11-01

    Mn and Cr K X-ray absorption edges were measured in various compounds containing Mn in Mn2+, Mn3+ and Mn4+ oxidation states and Cr in Cr3+ and Cr6+ oxidation states. Few compounds possess tetrahedral coordination in the 1st shell surrounding the cation while others possess octahedral coordination. Measurements have been carried out at the energy dispersive EXAFS beamline at INDUS-2 Synchrotron Radiation Source at Raja Ramanna Centre for Advanced Technology, Indore. Energy shifts of ∼8–16 eV were observed for Mn K edge in the Mn-compounds while a shift of 13–20 eV was observed for Cr K edge in Cr-compounds compared to values in elementalMn and Cr, respectively. The different chemical shifts observed for compounds having the same oxidation state of the cation but different anions or ligands show the effect of different chemical environments surrounding the cations in determining their X-ray absorption edges in the above compounds. The above chemical effect has been quantitatively described by determining the effective charges on Mn and Cr cations in the above compounds.

  6. Identification of zinc-ligated cysteine residues based on 13Calpha and 13Cbeta chemical shift data.

    Science.gov (United States)

    Kornhaber, Gregory J; Snyder, David; Moseley, Hunter N B; Montelione, Gaetano T

    2006-04-01

    Although a significant number of proteins include bound metals as part of their structure, the identification of amino acid residues coordinated to non-paramagnetic metals by NMR remains a challenge. Metal ligands can stabilize the native structure and/or play critical catalytic roles in the underlying biochemistry. An atom's chemical shift is exquisitely sensitive to its electronic environment. Chemical shift data can provide valuable insights into structural features, including metal ligation. In this study, we demonstrate that overlapped 13Cbeta chemical shift distributions of Zn-ligated and non-metal-ligated cysteine residues are largely resolved by the inclusion of the corresponding 13Calpha chemical shift information, together with secondary structural information. We demonstrate this with a bivariate distribution plot, and statistically with a multivariate analysis of variance (MANOVA) and hierarchical logistic regression analysis. Using 287 13Calpha/13Cbeta shift pairs from 79 proteins with known three-dimensional structures, including 86 13Calpha and 13Cbeta shifts for 43 Zn-ligated cysteine residues, along with corresponding oxidation state and secondary structure information, we have built a logistic regression model that distinguishes between oxidized cystines, reduced (non-metal ligated) cysteines, and Zn-ligated cysteines. Classifying cysteines/cystines with a statistical model incorporating all three phenomena resulted in a predictor of Zn ligation with a recall, precision and F-measure of 83.7%, and an accuracy of 95.1%. This model was applied in the analysis of Bacillus subtilis IscU, a protein involved in iron-sulfur cluster assembly. The model predicts that all three cysteines of IscU are metal ligands. We confirmed these results by (i) examining the effect of metal chelation on the NMR spectrum of IscU, and (ii) inductively coupled plasma mass spectrometry analysis. To gain further insight into the frequency of occurrence of non-cysteine Zn

  7. Algorithms for calculating mass-velocity and Darwin relativistic corrections with n-electron explicitly correlated Gaussians with shifted centers

    Science.gov (United States)

    Stanke, Monika; Palikot, Ewa; Adamowicz, Ludwik

    2016-05-01

    Algorithms for calculating the leading mass-velocity (MV) and Darwin (D) relativistic corrections are derived for electronic wave functions expanded in terms of n-electron explicitly correlated Gaussian functions with shifted centers and without pre-exponential angular factors. The algorithms are implemented and tested in calculations of MV and D corrections for several points on the ground-state potential energy curves of the H2 and LiH molecules. The algorithms are general and can be applied in calculations of systems with an arbitrary number of electrons.

  8. Structural Expression of Chemical Environment and C-13 NMR Chemical Shift for Carbons in Alcohols%脂肪醇分子碳环境结构表征与碳谱化学位移

    Institute of Scientific and Technical Information of China (English)

    刘树深; 徐红

    2000-01-01

    A novel atomic electronegative distance vector (AEDV) has been developed to express the chemical environment of various equivalent carbon in alcohols and four 4-parameter linear relationship between chemical shift and AEDV are created by using multiple linear regression.

  9. Quantitative and qualitative shifts in defensive metabolites define chemical defense investment during leaf development in Inga, a genus of tropical trees.

    Science.gov (United States)

    Wiggins, Natasha L; Forrister, Dale L; Endara, María-José; Coley, Phyllis D; Kursar, Thomas A

    2016-01-01

    Selective pressures imposed by herbivores are often positively correlated with investments that plants make in defense. Research based on the framework of an evolutionary arms race has improved our understanding of why the amount and types of defenses differ between plant species. However, plant species are exposed to different selective pressures during the life of a leaf, such that expanding leaves suffer more damage from herbivores and pathogens than mature leaves. We hypothesize that this differential selective pressure may result in contrasting quantitative and qualitative defense investment in plants exposed to natural selective pressures in the field. To characterize shifts in chemical defenses, we chose six species of Inga, a speciose Neotropical tree genus. Focal species represent diverse chemical, morphological, and developmental defense traits and were collected from a single site in the Amazonian rainforest. Chemical defenses were measured gravimetrically and by characterizing the metabolome of expanding and mature leaves. Quantitative investment in phenolics plus saponins, the major classes of chemical defenses identified in Inga, was greater for expanding than mature leaves (46% and 24% of dry weight, respectively). This supports the theory that, because expanding leaves are under greater selective pressure from herbivores, they rely more upon chemical defense as an antiherbivore strategy than do mature leaves. Qualitatively, mature and expanding leaves were distinct and mature leaves contained more total and unique metabolites. Intraspecific variation was greater for mature leaves than expanding leaves, suggesting that leaf development is canalized. This study provides a snapshot of chemical defense investment in a speciose genus of tropical trees during the short, few-week period of leaf development. Exploring the metabolome through quantitative and qualitative profiling enables a more comprehensive examination of foliar chemical defense investment.

  10. Free variable selection QSPR study to predict (19)F chemical shifts of some fluorinated organic compounds using Random Forest and RBF-PLS methods.

    Science.gov (United States)

    Goudarzi, Nasser

    2016-04-05

    In this work, two new and powerful chemometrics methods are applied for the modeling and prediction of the (19)F chemical shift values of some fluorinated organic compounds. The radial basis function-partial least square (RBF-PLS) and random forest (RF) are employed to construct the models to predict the (19)F chemical shifts. In this study, we didn't used from any variable selection method and RF method can be used as variable selection and modeling technique. Effects of the important parameters affecting the ability of the RF prediction power such as the number of trees (nt) and the number of randomly selected variables to split each node (m) were investigated. The root-mean-square errors of prediction (RMSEP) for the training set and the prediction set for the RBF-PLS and RF models were 44.70, 23.86, 29.77, and 23.69, respectively. Also, the correlation coefficients of the prediction set for the RBF-PLS and RF models were 0.8684 and 0.9313, respectively. The results obtained reveal that the RF model can be used as a powerful chemometrics tool for the quantitative structure-property relationship (QSPR) studies.

  11. High resolution NMR theory and chemical applications

    CERN Document Server

    Becker, Edwin D

    1969-01-01

    High Resolution NMR: Theory and Chemical Applications focuses on the applications of nuclear magnetic resonance (NMR), as well as chemical shifts, lattices, and couplings. The book first offers information on the theory of NMR, including nuclear spin and magnetic moment, spin lattice relaxation, line widths, saturation, quantum mechanical description of NMR, and ringing. The text then ponders on instrumentation and techniques and chemical shifts. Discussions focus on the origin of chemical shifts, reference compounds, empirical correlations of chemical shifts, modulation and phase detection,

  12. Predicting Heats of Explosion of Nitroaromatic Compounds through NBO Charges and 15N NMR Chemical Shifts of Nitro Groups

    OpenAIRE

    Ricardo Infante-Castillo; Samuel P. Hernández-Rivera

    2012-01-01

    This work presents a new quantitative model to predict the heat of explosion of nitroaromatic compounds using the natural bond orbital (NBO) charge and 15N NMR chemical shifts of the nitro groups (15NNitro) as structural parameters. The values of the heat of explosion predicted for 21 nitroaromatic compounds using the model described here were compared with experimental data. The prediction ability of the model was assessed by the leave-one-out cross-validation method. The cross-validation re...

  13. The Effect of Molecular Conformation on the Accuracy of Theoretical (1)H and (13)C Chemical Shifts Calculated by Ab Initio Methods for Metabolic Mixture Analysis.

    Science.gov (United States)

    Chikayama, Eisuke; Shimbo, Yudai; Komatsu, Keiko; Kikuchi, Jun

    2016-04-14

    NMR spectroscopy is a powerful method for analyzing metabolic mixtures. The information obtained from an NMR spectrum is in the form of physical parameters, such as chemical shifts, and construction of databases for many metabolites will be useful for data interpretation. To increase the accuracy of theoretical chemical shifts for development of a database for a variety of metabolites, the effects of sets of conformations (structural ensembles) and the levels of theory on computations of theoretical chemical shifts were systematically investigated for a set of 29 small molecules in the present study. For each of the 29 compounds, 101 structures were generated by classical molecular dynamics at 298.15 K, and then theoretical chemical shifts for 164 (1)H and 123 (13)C atoms were calculated by ab initio quantum chemical methods. Six levels of theory were used by pairing Hartree-Fock, B3LYP (density functional theory), or second order Møller-Plesset perturbation with 6-31G or aug-cc-pVDZ basis set. The six average fluctuations in the (1)H chemical shift were ±0.63, ± 0.59, ± 0.70, ± 0.62, ± 0.75, and ±0.66 ppm for the structural ensembles, and the six average errors were ±0.34, ± 0.27, ± 0.32, ± 0.25, ± 0.32, and ±0.25 ppm. The results showed that chemical shift fluctuations with changes in the conformation because of molecular motion were larger than the differences between computed and experimental chemical shifts for all six levels of theory. In conclusion, selection of an appropriate structural ensemble should be performed before theoretical chemical shift calculations for development of an accurate database for a variety of metabolites.

  14. Effect of pH, urea, peptide length, and neighboring amino acids on alanine alpha-proton random coil chemical shifts.

    Science.gov (United States)

    Carlisle, Elizabeth A; Holder, Jessica L; Maranda, Abby M; de Alwis, Adamberage R; Selkie, Ellen L; McKay, Sonya L

    2007-01-01

    Accurate random coil alpha-proton chemical shift values are essential for precise protein structure analysis using chemical shift index (CSI) calculations. The current study determines the chemical shift effects of pH, urea, peptide length and neighboring amino acids on the alpha-proton of Ala using model peptides of the general sequence GnXaaAYaaGn, where Xaa and Yaa are Leu, Val, Phe, Tyr, His, Trp or Pro, and n = 1-3. Changes in pH (2-6), urea (0-1M), and peptide length (n = 1-3) had no effect on Ala alpha-proton chemical shifts. Denaturing concentrations of urea (8M) caused significant downfield shifts (0.10 +/- 0.01 ppm) relative to an external DSS reference. Neighboring aliphatic residues (Leu, Val) had no effect, whereas aromatic amino acids (Phe, Tyr, His and Trp) and Pro caused significant shifts in the alanine alpha-proton, with the extent of the shifts dependent on the nature and position of the amino acid. Smaller aromatic residues (Phe, Tyr, His) caused larger shift effects when present in the C-terminal position (approximately 0.10 vs. 0.05 ppm N-terminal), and the larger aromatic tryptophan caused greater effects in the N-terminal position (0.15 ppm vs. 0.10 C-terminal). Proline affected both significant upfield (0.06 ppm, N-terminal) and downfield (0.25 ppm, C-terminal) chemical shifts. These new Ala correction factors detail the magnitude and range of variation in environmental chemical shift effects, in addition to providing insight into the molecular level interactions that govern protein folding.

  15. NMR chemical shift as analytical derivative of the Helmholtz free energy.

    Science.gov (United States)

    Van den Heuvel, Willem; Soncini, Alessandro

    2013-02-07

    We present a theory for the temperature-dependent nuclear magnetic shielding tensor of molecules with arbitrary electronic structure. The theory is a generalization of Ramsey's theory for closed-shell molecules. The shielding tensor is defined as a second derivative of the Helmholtz free energy of the electron system in equilibrium with the applied magnetic field and the nuclear magnetic moments. This derivative is analytically evaluated and expressed as a sum over states formula. Special consideration is given to a system with an isolated degenerate ground state for which the size of the degeneracy and the composition of the wave functions are arbitrary. In this case, the paramagnetic part of the shielding tensor is expressed in terms of the g and A tensors of the electron paramagnetic resonance spin Hamiltonian of the degenerate state. As an illustration of the proposed theory, we provide an explicit formula for the paramagnetic shift of the central lanthanide ion in endofullerenes Ln@C(60), with Ln = Ce(3+), Nd(3+), Sm(3+), Dy(3+), Er(3+), and Yb(3+), where the ground state can be a strongly spin-orbit coupled icosahedral sextet for which the paramagnetic shift cannot be described by previous theories.

  16. Modeling the chemical shift of lanthanide 4f electron binding energies

    NARCIS (Netherlands)

    Dorenbos, P.

    2012-01-01

    Lanthanides in compounds can adopt the tetravalent [Xe]4fn−1 (like Ce4+, Pr4+, Tb4+), the trivalent [Xe]4fn (all lanthanides), or the divalent [Xe]4f n+1 configuration (like Eu2+, Yb2+, Sm2+, Tm2+). The 4f-electron binding energy depends on the charge Q of the lanthanide ion and its chemical environ

  17. The correlation between urinary 5-hydroxyindoleacetic acid and sperm quality in infertile men and rotating shift workers

    Directory of Open Access Journals (Sweden)

    Pariente José A

    2010-11-01

    Full Text Available Abstract Background Serotonin is a neurotransmitter that modulates a wide range of neuroendocrine functions. However, excessive circulating serotonin levels may induce harmful effects in the male reproductive system. The objective of this study was to evaluate whether the levels of urinary 5-hydroxyindoleacetic acid (5-HIIA, a major serotonin metabolite, correlate with different classical seminal parameters. Methods Human ejaculates were obtained from 40 men attending infertility counselling and rotating shift workers by masturbation after 4-5 days of abstinence. Urinary 5- HIIA concentration was quantified by using a commercial ELISA kit. Forward motility was assessed by a computer-aided semen analysis (CASA system. Sperm concentration was determined using the haemocytometer method. Sperm morphology was evaluated after Diff-Quik staining, while sperm vitality was estimated after Eosin-Nigrosin vital staining. Results Our results show that urinary 5-HIIA levels obtained from a set of 20 volunteers negatively correlated with sperm concentration, forward motility, morphology normal range and sperm vitality. On the other hand, we checked the relationship between male infertility and urinary 5-HIIA levels in 20 night shift workers. Thus, urinary 5-HIIA levels obtained from 10 recently-proven fathers were significantly lower than those found in 10 infertile males. Additionally, samples from recent fathers exhibited higher sperm concentration, as well as better forward motility and normal morphology rate. Conclusions In the light of our findings, we concluded that high serotonin levels, indirectly measured as urinary 5-HIIA levels, appear to play a role as an infertility determinant in male subjects.

  18. Nuclear Magnetic Resonance-Assisted Prediction of Secondary Structure for RNA: Incorporation of Direction-Dependent Chemical Shift Constraints.

    Science.gov (United States)

    Chen, Jonathan L; Bellaousov, Stanislav; Tubbs, Jason D; Kennedy, Scott D; Lopez, Michael J; Mathews, David H; Turner, Douglas H

    2015-11-17

    Knowledge of RNA structure is necessary to determine structure-function relationships and to facilitate design of potential therapeutics. RNA secondary structure prediction can be improved by applying constraints from nuclear magnetic resonance (NMR) experiments to a dynamic programming algorithm. Imino proton walks from NOESY spectra reveal double-stranded regions. Chemical shifts of protons in GH1, UH3, and UH5 of GU pairs, UH3, UH5, and AH2 of AU pairs, and GH1 of GC pairs were analyzed to identify constraints for the 5' to 3' directionality of base pairs in helices. The 5' to 3' directionality constraints were incorporated into an NMR-assisted prediction of secondary structure (NAPSS-CS) program. When it was tested on 18 structures, including nine pseudoknots, the sensitivity and positive predictive value were improved relative to those of three unrestrained programs. The prediction accuracy for the pseudoknots improved the most. The program also facilitates assignment of chemical shifts to individual nucleotides, a necessary step for determining three-dimensional structure.

  19. Heat Integration of the Water-Gas Shift Reaction System for Carbon Sequestration Ready IGCC Process with Chemical Looping

    Energy Technology Data Exchange (ETDEWEB)

    Juan M. Salazara; Stephen E. Zitney; Urmila M. Diwekara

    2010-01-01

    Integrated gasification combined cycle (IGCC) technology has been considered as an important alternative for efficient power systems that can reduce fuel consumption and CO2 emissions. One of the technological schemes combines water-gas shift reaction and chemical-looping combustion as post gasification techniques in order to produce sequestration-ready CO2 and potentially reduce the size of the gas turbine. However, these schemes have not been energetically integrated and process synthesis techniques can be applied to obtain an optimal flowsheet. This work studies the heat exchange network synthesis (HENS) for the water-gas shift reaction train employing a set of alternative designs provided by Aspen energy analyzer (AEA) and combined in a process superstructure that was simulated in Aspen Plus (AP). This approach allows a rigorous evaluation of the alternative designs and their combinations avoiding all the AEA simplifications (linearized models of heat exchangers). A CAPE-OPEN compliant capability which makes use of a MINLP algorithm for sequential modular simulators was employed to obtain a heat exchange network that provided a cost of energy that was 27% lower than the base case. Highly influential parameters for the pos gasification technologies (i.e. CO/steam ratio, gasifier temperature and pressure) were calculated to obtain the minimum cost of energy while chemical looping parameters (oxidation and reduction temperature) were ensured to be satisfied.

  20. Theory of NMR chemical shift in an electronic state with arbitrary degeneracy

    CERN Document Server

    Heuvel, Willem Van den

    2012-01-01

    We present a theory of nuclear magnetic resonance (NMR) shielding tensors for electronic states with arbitrary degeneracy. The shieldings are here expressed in terms of generalized Zeeman ($g^{(k)}$) and hyperfine ($A^{(k)}$) tensors, of all ranks $k$ allowed by the size of degeneracy. Contrary to recent proposals [T. O. Pennanen and J. Vaara, Phys. Rev. Lett. 100, 133002 (2008)], our theory is valid in the strong spin-orbit coupling limit. Ab initio calculations for the 4-fold degenerate $\\Gamma_8$ ground state of lanthanide-doped fluorite crystals CaF$_2$:Ln (Ln = Pr$^{2+}$, Nd$^{3+}$, Sm$^{3+}$, and Dy$^{3+}$) show that previously neglected contributions can account for more than 50% of the paramagnetic shift.

  1. Quantitative analysis of deuterium using the isotopic effect on quaternary {sup 13}C NMR chemical shifts

    Energy Technology Data Exchange (ETDEWEB)

    Darwish, Tamim A., E-mail: tamim.darwish@ansto.gov.au [National Deuteration Facility, Australian Nuclear Science and Technology Organisation, Locked Bag 21, Kirrawee DC, NSW 2232 (Australia); Yepuri, Nageshwar Rao; Holden, Peter J. [National Deuteration Facility, Australian Nuclear Science and Technology Organisation, Locked Bag 21, Kirrawee DC, NSW 2232 (Australia); James, Michael [Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria 3168 (Australia)

    2016-07-13

    Quantitative analysis of specifically deuterated compounds can be achieved by a number of conventional methods, such as mass spectroscopy, or by quantifying the residual {sup 1}H NMR signals compared to signals from internal standards. However, site specific quantification using these methods becomes challenging when dealing with non-specifically or randomly deuterated compounds that are produced by metal catalyzed hydrothermal reactions in D{sub 2}O, one of the most convenient deuteration methods. In this study, deuterium-induced NMR isotope shifts of quaternary {sup 13}C resonances neighboring deuterated sites have been utilized to quantify the degree of isotope labeling of molecular sites in non-specifically deuterated molecules. By probing {sup 13}C NMR signals while decoupling both proton and deuterium nuclei, it is possible to resolve {sup 13}C resonances of the different isotopologues based on the isotopic shifts and the degree of deuteration of the carbon atoms. We demonstrate that in different isotopologues, the same quaternary carbon, neighboring partially deuterated carbon atoms, are affected to an equal extent by relaxation. Decoupling both nuclei ({sup 1}H, {sup 2}H) resolves closely separated quaternary {sup 13}C signals of the different isotopologues, and allows their accurate integration and quantification under short relaxation delays (D1 = 1 s) and hence fast accumulative spectral acquisition. We have performed a number of approaches to quantify the deuterium content at different specific sites to demonstrate a convenient and generic analysis method for use in randomly deuterated molecules, or in cases of specifically deuterated molecules where back-exchange processes may take place during work up. - Graphical abstract: The relative intensities of quaternary {sup 13}C {"1H,"2H} resonances are equal despite the different relaxation delays, allowing the relative abundance of the different deuterated isotopologues to be calculated using NMR fast

  2. Correlations between (51)V solid-state NMR parameters and chemical structure of vanadium (V) complexes as models for related metalloproteins and catalysts.

    Science.gov (United States)

    Fenn, Annika; Wächtler, Maria; Gutmann, Torsten; Breitzke, Hergen; Buchholz, Axel; Lippold, Ines; Plass, Winfried; Buntkowsky, Gerd

    2009-12-01

    The parameters describing the quadrupolar and CSA interactions of 51V solid-state MAS NMR investigations of model complexes mimicking vanadoenzymes as well as vanadium containing catalysts and enzyme complexes are interpreted with respect to the chemical structure. The interpretation is based on the data of 15 vanadium complexes including two new complexes with previously unpublished data and 13 complexes with data previously published by us. Correlations between the chemical structure and the 51V solid-state NMR data of this class of compounds have been established. Especially for the isotropic chemical shift delta(iso) and the chemical shift anisotropy delta(sigma), correlations with specific structural features like the coordination number of the vanadium atom, the number of coordinating nitrogens, the number of oxygen atoms and the chemical surrounding of the complex could be established for these compounds. Moreover, quantitative correlations between the solid-state NMR parameters and specific bond angles and bond lengths have been obtained. Our results can be of particular interest for future investigations concerning the structure and the mode of action of related vanadoenzymes and vanadate protein assemblies, including the use of vanadate adducts as transition state analogs for phosphate metabolizing systems.

  3. NMR chemical shift as analytical derivative of the Helmholtz free energy

    CERN Document Server

    Heuvel, Willem Van den

    2012-01-01

    We present a theory for the temperature-dependent nuclear magnetic shielding tensor of molecules with arbitrary electronic structure. The theory is a generalization of Ramsey's theory for closed-shell molecules. The shielding tensor is defined as a second derivative of the Helmholtz free energy of the electron system in equilibrium with the applied magnetic field and the nuclear magnetic moments. This derivative is analytically evaluated and expressed as a sum over states formula. Special consideration is given to a system with an isolated degenerate ground state for which the size of the degeneracy and the composition of the wave functions are arbitrary. In this case the paramagnetic part of the shielding tensor is expressed in terms of the $g$ and $A$ tensors of the EPR spin Hamiltonian of the degenerate state. As an illustration of the proposed theory, we provide an explicit formula for the paramagnetic shift of the central lanthanide ion in endofullerenes Ln@C$_{60}$, with Ln=Ce$^{3+}$, Nd$^{3+}$, Sm$^{3+...

  4. Mode shifting in school travel mode: examining the prevalence and correlates of active school transport in Ontario, Canada

    Directory of Open Access Journals (Sweden)

    Buliung Ron

    2011-08-01

    Full Text Available Abstract Background Studies examining the correlates of school transport commonly fail to make the distinction between morning and afternoon school trips. The purpose of this study was to examine the prevalence and correlates of mode shift from passive in the morning to active in the afternoon among elementary and secondary school students in Ontario, Canada. Methods Data were derived from the 2009 cycle of the Ontario Student Drug Use and Health Survey (OSDUHS. 3,633 students in grades 7 through 12 completed self-administered questionnaires. Socio-demographic, behavioural, psychological, and environmental predictors of active school transport (AST were assessed using logistic regression. Results Overall, 47% and 38% of elementary school students reported AST to and from school, respectively. The corresponding figures were 23% and 32% for secondary school students. The prevalence of AST varied temporarily and spatially. There was a higher prevalence of walking/biking found for elementary school students than for secondary school students, and there was an approximate 10% increase in AST in the afternoon. Different correlates of active school transport were also found across elementary and secondary school students. For all ages, students living in urban areas, with a shorter travel time between home and school, and having some input to the decision making process, were more likely to walk to and from school. Conclusions Future research examining AST should continue to make the analytic distinction between the morning and afternoon trip, and control for the moderating effect of age and geography in predicting mode choice. In terms of practice, these variations highlight the need for school-specific travel plans rather than 'one size fits all' interventions in promoting active school transport.

  5. Chemical shift magnetic resonance spectroscopy of cingulate grey matter in patients with minimal hepatic encephalopathy

    Energy Technology Data Exchange (ETDEWEB)

    Mechtcheriakov, Sergei; Kugener, Andre; Mattedi, Michael; Hinterhuber, Hartmann; Marksteiner, Josef [Innsbruck Medical University, Department of General Psychiatry, Innsbruck (Austria); Schocke, Michael [Innsbruck Medical University, Department of Radiology I, Innsbruck (Austria); Graziadei, Ivo W.; Vogel, Wolfgang [Innsbruck Medical University, Department of Gastroenterology, Innsbruck (Austria)

    2005-01-01

    Minimal hepatic encephalopathy (MHE) is frequently diagnosed in patients with liver cirrhosis who do not show overt clinical cirrhosis-associated neurological deficits. This condition manifests primarily with visuo-motor and attention deficits. We studied the association between visuo-motor deficits and magnetic resonance spectroscopic parameters in cingulate grey matter and white matter of centrum semiovale in patients with liver cirrhosis. The data revealed an increase in the glutamate-glutamine/creatine ratio and a decrease in choline/creatine and inositol/creatine ratios in patients with liver cirrhosis. The analysis of the data showed that cirrhosis-associated deterioration of the visuo-motor function significantly correlates with a decrease in the choline/creatine ratio and an increase in N-acetylaspartate/choline in cingulate grey matter but not in the neighbouring white matter. Furthermore, the increase in the glutamate-glutamine/creatine ratio correlated significantly with the increase in the N-acetylaspartate/creatine ratio. These data suggest an association between altered choline, glutamate-glutamine and NAA metabolism in cingulate grey matter and symptoms of MHE, and underline the importance of differentiation between grey and white matter in magnetic resonance spectroscopic studies on patients with cirrhosis-associated brain dysfunction. (orig.)

  6. Synthesis, NMR spectroscopic characterization and structure of a divinyldisilazane-(triphenylphosphine)platinum(0) complex: observation of isotope-induced chemical shifts (1)Δ(12/13)C((195)Pt).

    Science.gov (United States)

    Wrackmeyer, Bernd; Klimkina, Elena V; Schmalz, Thomas; Milius, Wolfgang

    2013-05-01

    Tetramethyldivinyldisilazane-(triphenylphosphine)platinum(0) was prepared, characterized in solid state by X-ray crystallography and in solution by multinuclear magnetic resonance spectroscopy ((1)H, (13)C, (15)N, (29)Si, (31)P and (195)Pt NMR). Numerous signs of spin-spin coupling constants were determined by two-dimensional heteronuclear shift correlations (HETCOR) and two-dimensional (1)H/(1)H COSY experiments. Isotope-induced chemical shifts (1)Δ(12/13)C((195)Pt) were measured from (195)Pt NMR spectra of the title compound as well as of other Pt(0), Pt(II) and Pt(IV) compounds for comparison. In contrast to other heavy nuclei such as (199)Hg or (207)Pb, the "normal" shifts of the heavy isotopomers to low frequencies are found, covering a range of >500 ppb.

  7. Chemical structure elucidation from ¹³C NMR chemical shifts: efficient data processing using bipartite matching and maximal clique algorithms.

    Science.gov (United States)

    Koichi, Shungo; Arisaka, Masaki; Koshino, Hiroyuki; Aoki, Atsushi; Iwata, Satoru; Uno, Takeaki; Satoh, Hiroko

    2014-04-28

    Computer-assisted chemical structure elucidation has been intensively studied since the first use of computers in chemistry in the 1960s. Most of the existing elucidators use a structure-spectrum database to obtain clues about the correct structure. Such a structure-spectrum database is expected to grow on a daily basis. Hence, the necessity to develop an efficient structure elucidation system that can adapt to the growth of a database has been also growing. Therefore, we have developed a new elucidator using practically efficient graph algorithms, including the convex bipartite matching, weighted bipartite matching, and Bron-Kerbosch maximal clique algorithms. The utilization of the two matching algorithms especially is a novel point of our elucidator. Because of these sophisticated algorithms, the elucidator exactly produces a correct structure if all of the fragments are included in the database. Even if not all of the fragments are in the database, the elucidator proposes relevant substructures that can help chemists to identify the actual chemical structures. The elucidator, called the CAST/CNMR Structure Elucidator, plays a complementary role to the CAST/CNMR Chemical Shift Predictor, and together these two functions can be used to analyze the structures of organic compounds.

  8. Chemical shift powder spectra enhanced by multiple-contact cross-polarization under slow magic-angle spinning

    Science.gov (United States)

    Raya, Jésus; Perrone, Barbara; Hirschinger, Jérôme

    2013-02-01

    A simple multiple-contact cross-polarization (CP) scheme is applied to a powder sample of ferrocene and β-calcium formate under static and magic-angle spinning (MAS) conditions. The method is described analytically through the density matrix formalism. We show that multiple equilibrations-re-equilibrations with the proton spin bath improves the polarization transfer efficiency at short contact times and provides higher signal enhancements than state-of-the art techniques such as adiabatic passage through the Hartmann-Hahn condition CP (APHH-CP) when MAS is applied. The resulting chemical shift powder spectra then are identical to the ones obtained by using ROtor-Directed Exchange of Orientations CP (APHH-RODEO-CP) with intensity gains of a factor 1.1-1.3.

  9. 13C-NMR chemical shift databases as a quick tool to evaluate structural models of humic substances

    DEFF Research Database (Denmark)

    Nyrop Albers, Christian; Hansen, Poul Erik

    2010-01-01

    Models for humic and fulvic acids are discussed based on 13C liquid state NMR spectra combined with results from elemental analysis and titration studies. The analysis of NMR spectra is based on a full reconstruction of the NMR spectrum done with help of 13C-NMR data bases by adding up chemical...... side missing structural elements in the models can be suggested. A number of proposed structures for humic and fulvic acids are discussed based on the above analysis....... shifts of all substructures from the proposed models. A full reconstruction makes sure that all carbons are accounted for and enables on the negative side to discuss structural elements identified from recorded spectra of humic substances that cannot be observed in the simulated spectrum. On the positive...

  10. Chemical shift powder spectra enhanced by multiple-contact cross-polarization under slow magic-angle spinning.

    Science.gov (United States)

    Raya, Jésus; Perrone, Barbara; Hirschinger, Jérôme

    2013-02-01

    A simple multiple-contact cross-polarization (CP) scheme is applied to a powder sample of ferrocene and β-calcium formate under static and magic-angle spinning (MAS) conditions. The method is described analytically through the density matrix formalism. We show that multiple equilibrations-re-equilibrations with the proton spin bath improves the polarization transfer efficiency at short contact times and provides higher signal enhancements than state-of-the art techniques such as adiabatic passage through the Hartmann-Hahn condition CP (APHH-CP) when MAS is applied. The resulting chemical shift powder spectra then are identical to the ones obtained by using ROtor-Directed Exchange of Orientations CP (APHH-RODEO-CP) with intensity gains of a factor 1.1-1.3.

  11. Portable Sequentially Shifted Excitation Raman spectroscopy as an innovative tool for in situ chemical interrogation of painted surfaces.

    Science.gov (United States)

    Conti, Claudia; Botteon, Alessandra; Bertasa, Moira; Colombo, Chiara; Realini, Marco; Sali, Diego

    2016-08-07

    We present the first validation and application of portable Sequentially Shifted Excitation (SSE) Raman spectroscopy for the survey of painted layers in art. The method enables the acquisition of shifted Raman spectra and the recovery of the spectral data through the application of a suitable reconstruction algorithm. The technique has a great potentiality in art where commonly a strong fluorescence obscures the Raman signal of the target, especially when conventional portable Raman spectrometers are used for in situ analyses. Firstly, the analytical capability of portable SSE Raman spectroscopy is critically discussed using reference materials and laboratory specimens, comparing its results with other conventional high performance laboratory instruments (benchtop FT-Raman and dispersive Raman spectrometers with an external fiber optic probe); secondly, it is applied directly in situ to study the complex polychromy of Italian prestigious terracotta sculptures of the 16(th) century. Portable SSE Raman spectroscopy represents a new investigation modality in art, expanding the portfolio of non-invasive, chemically specific analytical tools.

  12. Microscopic structures of ionic liquids 1-ethyl-3-methylimidazolium tetrafluoroborate in water probed by the relative chemical shift

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The relative chemical shifts (△δ) △δwere put forward to investigate the microscopic structure of 1-ethyl-3-methyl-imidazolium tetrafluoroborate (EmimBF4) during the dilution process with water.The concentration-dependent △δ(C2)H-(C4)H,△δ(C2)H-(C5)H and △δ(C4)H-(C5)H were analyzed.The results reveal that the variations of the microscopic structures of three aromatic protons are inconsistent.The strength of the H-bond between water and three aromatic protons follows the order:(C2)H···O > (C4)H···O > (C5)H···O.The concentration-dependent △δ(C6)H-(C7)H and △δ(C6)H-(C8)H indicate the formation of the H-bonds of (Calkyl)H···O is impossible,and more water is located around (C6)H than around (C7)H or (C8)H.The concentration-dependent △δ(C2)H-(C4)H and △δ(C2)H-(C5)H both increase rapidly when xwater > 0.9 or so,suggesting the ionic pairs of EmimBF4 are dissociated rapidly.The turning points of concentration-dependent △δ(C2)H-(C4)H and △δ(C2)H-(C5)H indicate that some physical properties of the EmimBF4/water mixtures also change at the corresponding concentration point.The microscopic structures of EmimBF4 in water could be clearly detected by the relative chemical shifts.

  13. Thickness-Dependent Binding Energy Shift in Few-Layer MoS2 Grown by Chemical Vapor Deposition.

    Science.gov (United States)

    Lin, Yu-Kai; Chen, Ruei-San; Chou, Tsu-Chin; Lee, Yi-Hsin; Chen, Yang-Fang; Chen, Kuei-Hsien; Chen, Li-Chyong

    2016-08-31

    The thickness-dependent surface states of MoS2 thin films grown by the chemical vapor deposition process on the SiO2-Si substrates are investigated by X-ray photoelectron spectroscopy. Raman and high-resolution transmission electron microscopy suggest the thicknesses of MoS2 films to be ranging from 3 to 10 layers. Both the core levels and valence band edges of MoS2 shift downward ∼0.2 eV as the film thickness increases, which can be ascribed to the Fermi level variations resulting from the surface states and bulk defects. Grainy features observed from the atomic force microscopy topographies, and sulfur-vacancy-induced defect states illustrated at the valence band spectra imply the generation of surface states that causes the downward band bending at the n-type MoS2 surface. Bulk defects in thick MoS2 may also influence the Fermi level oppositely compared to the surface states. When Au contacts with our MoS2 thin films, the Fermi level downshifts and the binding energy reduces due to the hole-doping characteristics of Au and easy charge transfer from the surface defect sites of MoS2. The shift of the onset potentials in hydrogen evolution reaction and the evolution of charge-transfer resistances extracted from the impedance measurement also indicate the Fermi level varies with MoS2 film thickness. The tunable Fermi level and the high chemical stability make our MoS2 a potential catalyst. The observed thickness-dependent properties can also be applied to other transition-metal dichalcogenides (TMDs), and facilitates the development in the low-dimensional electronic devices and catalysts.

  14. VITAL NMR: Using Chemical Shift Derived Secondary Structure Information for a Limited Set of Amino Acids to Assess Homology Model Accuracy

    Energy Technology Data Exchange (ETDEWEB)

    Brothers, Michael C [University of Illinois, Urbana-Champaign; Nesbitt, Anna E [University of Illinois, Urbana-Champaign; Hallock, Michael J [University of Illinois, Urbana-Champaign; Rupasinghe, Sanjeewa [University of Illinois, Urbana-Champaign; Tang, Ming [University of Illinois, Urbana-Champaign; Harris, Jason B [ORNL; Baudry, Jerome Y [ORNL; Schuler, Mary A [University of Illinois, Urbana-Champaign; Rienstra, Chad M [University of Illinois, Urbana-Champaign

    2011-01-01

    Homology modeling is a powerful tool for predicting protein structures, whose success depends on obtaining a reasonable alignment between a given structural template and the protein sequence being analyzed. In order to leverage greater predictive power for proteins with few structural templates, we have developed a method to rank homology models based upon their compliance to secondary structure derived from experimental solid-state NMR (SSNMR) data. Such data is obtainable in a rapid manner by simple SSNMR experiments (e.g., (13)C-(13)C 2D correlation spectra). To test our homology model scoring procedure for various amino acid labeling schemes, we generated a library of 7,474 homology models for 22 protein targets culled from the TALOS+/SPARTA+ training set of protein structures. Using subsets of amino acids that are plausibly assigned by SSNMR, we discovered that pairs of the residues Val, Ile, Thr, Ala and Leu (VITAL) emulate an ideal dataset where all residues are site specifically assigned. Scoring the models with a predicted VITAL site-specific dataset and calculating secondary structure with the Chemical Shift Index resulted in a Pearson correlation coefficient (-0.75) commensurate to the control (-0.77), where secondary structure was scored site specifically for all amino acids (ALL 20) using STRIDE. This method promises to accelerate structure procurement by SSNMR for proteins with unknown folds through guiding the selection of remotely homologous protein templates and assessing model quality.

  15. VITAL NMR: using chemical shift derived secondary structure information for a limited set of amino acids to assess homology model accuracy

    Energy Technology Data Exchange (ETDEWEB)

    Brothers, Michael C.; Nesbitt, Anna E.; Hallock, Michael J. [University of Illinois at Urbana-Champaign, Department of Chemistry (United States); Rupasinghe, Sanjeewa G. [University of Illinois at Urbana-Champaign, Department of Cell and Developmental Biology (United States); Tang Ming [University of Illinois at Urbana-Champaign, Department of Chemistry (United States); Harris, Jason; Baudry, Jerome [University of Tennessee, Department of Biochemistry, Cellular and Molecular Biology (United States); Schuler, Mary A. [University of Illinois at Urbana-Champaign, Department of Cell and Developmental Biology (United States); Rienstra, Chad M., E-mail: rienstra@illinois.edu [University of Illinois at Urbana-Champaign, Department of Chemistry (United States)

    2012-01-15

    Homology modeling is a powerful tool for predicting protein structures, whose success depends on obtaining a reasonable alignment between a given structural template and the protein sequence being analyzed. In order to leverage greater predictive power for proteins with few structural templates, we have developed a method to rank homology models based upon their compliance to secondary structure derived from experimental solid-state NMR (SSNMR) data. Such data is obtainable in a rapid manner by simple SSNMR experiments (e.g., {sup 13}C-{sup 13}C 2D correlation spectra). To test our homology model scoring procedure for various amino acid labeling schemes, we generated a library of 7,474 homology models for 22 protein targets culled from the TALOS+/SPARTA+ training set of protein structures. Using subsets of amino acids that are plausibly assigned by SSNMR, we discovered that pairs of the residues Val, Ile, Thr, Ala and Leu (VITAL) emulate an ideal dataset where all residues are site specifically assigned. Scoring the models with a predicted VITAL site-specific dataset and calculating secondary structure with the Chemical Shift Index resulted in a Pearson correlation coefficient (-0.75) commensurate to the control (-0.77), where secondary structure was scored site specifically for all amino acids (ALL 20) using STRIDE. This method promises to accelerate structure procurement by SSNMR for proteins with unknown folds through guiding the selection of remotely homologous protein templates and assessing model quality.

  16. Zero discharge tanning: a shift from chemical to biocatalytic leather processing.

    Science.gov (United States)

    Thanikaivelan, Palanisamy; Rao, Jonnalagadda Raghava; Nair, Balachandran Unni; Ramasami, Thirumalachari

    2002-10-01

    Beam house processes (Beam house processes generally mean liming-reliming processes, which employ beam.) contribute more than 60% of the total pollution from leather processing. The use of lime and sodium sulfide is of environmental concern (1, 2). Recently, the authors have developed an enzyme-based dehairing assisted with a very low amount of sodium sulfide, which completely avoids the use of lime. However, the dehaired pelt requires opening up of fiber bundles for further processing, where lime is employed to achieve this through osmotic swelling. Huge amounts of lime sludge and total solids are the main drawbacks of lime. An alternative bioprocess, based on alpha-amylase for fiber opening, has been attempted after enzymatic unhairing. This totally eliminates the use of lime in leather processing. This method enables subsequent processes and operations in leather making feasible without a deliming process. A control experiment was run in parallel using conventional liming-reliming processes. It has been found that the extent of opening up of fiber bundles using alpha-amylase is comparable to that of the control. This has been substantiated through scanning electron microscopic, stratigraphic chrome distribution analysis, and softness measurements. Performance of the leathers is shown to be on a par with leathers produced by the conventional process through physical and hand evaluation. Importantly, softness of the leathers is numerically proven to be comparable with that of control. The process also demonstrates reduction in chemical oxygen demand load by 45% and total solids load by 20% compared to the conventional process. The total dry sludge from the beam house processes is brought down from 152 to 8 kg for processing 1 ton of raw hides.

  17. Comparison of experimental and DFT-calculated NMR chemical shifts of 2-amino and 2-hydroxyl substituted phenyl benzimidazoles, benzoxazoles and benzothiazoles in four solvents using the IEF-PCM solvation model.

    Science.gov (United States)

    Pierens, Gregory K; Venkatachalam, T K; Reutens, David C

    2016-04-01

    A comparative study of experimental and calculated NMR chemical shifts of six compounds comprising 2-amino and 2-hydroxy phenyl benzoxazoles/benzothiazoles/benzimidazoles in four solvents is reported. The benzimidazoles showed interesting spectral characteristics, which are discussed. The proton and carbon chemical shifts were similar for all solvents. The largest chemical shift deviations were observed in benzene. The chemical shifts were calculated with density functional theory using a suite of four functionals and basis set combinations. The calculated chemical shifts revealed a good match to the experimentally observed values in most of the solvents. The mean absolute error was used as the primary metric. The use of an additional metric is suggested, which is based on the order of chemical shifts. The DP4 probability measures were also used to compare the experimental and calculated chemical shifts for each compound in the four solvents. Copyright © 2015 John Wiley & Sons, Ltd.

  18. Chemical shift imaging at 3 Tesla: effect of echo time on assessing bone marrow abnormalities

    Energy Technology Data Exchange (ETDEWEB)

    Del Grande, F. [The Johns Hopkins Medical Institutions, The Russell H. Morgan Department of Radiology and Radiological Science, Baltimore, MD (United States); Ospedale Regionale di Lugano, Servizio di Radiologia, Lugano, TI (Switzerland); Subhawong, Ty [University of Miami Miller School of Medicine, Department of Radiology, Miami, FL (United States); Flammang, A. [Siemens Medical Solutions USA, Inc., Malvern, PA (United States); Fayad, L.M. [The Johns Hopkins Medical Institutions, The Russell H. Morgan Department of Radiology and Radiological Science, Baltimore, MD (United States)

    2014-08-15

    Our purpose is to test the effect of varied in-phase (IP) and opposed-phase (OP) sequence order on characterizing marrow signal changes at 3T. The study was HIPAA compliant and IRB approved. Informed consent was waived. At 3T, IP and OP sequences were acquired in three patients with biopsy-proven osteosarcomas, using two methods: approach 1 (OP acquisition before IP acquisition) and approach 2 (OP after IP). Signal intensity (SI) measurements in 12 locations of biopsy-proven osteosarcoma and in six locations with normal bone marrow were performed independently by two experienced musculoskeletal radiologists. The signal intensity ratio (SIR) was measured within the marrow where there was T1 signal lower than skeletal muscle. A SIR < 20 % on the OP compared with IP imaging was considered positive for marrow replacement, while SIR > = 20 % was considered negative. Interobserver agreement was measured by the Lin concordance correlation coefficient (CCC). In 75 % (18/24) of locations within the biopsy-proven tumors, the SIR was >20 % (SI drop more than 20 % in OP compared to IP) using approach 2 and in 100 % (24/24) of the locations the SIR was <20 % (SI drop less than 20 % in OP compared to IP) using approach 1, indicating a high percentage of false-negative results by approach 2, and no false-negative results with approach 1. There was good agreement between observer measurement (CCC = 0.96). At 3T, the OP sequence should be acquired prior to the IP sequence, because susceptibility artifacts on a later-acquired OP sequence may lead to an erroneous interpretation of marrow signal abnormalities. (orig.)

  19. High-Frequency (1)H NMR Chemical Shifts of Sn(II) and Pb(II) Hydrides Induced by Relativistic Effects: Quest for Pb(II) Hydrides.

    Science.gov (United States)

    Vícha, Jan; Marek, Radek; Straka, Michal

    2016-10-17

    The role of relativistic effects on (1)H NMR chemical shifts of Sn(II) and Pb(II) hydrides is investigated by using fully relativistic DFT calculations. The stability of possible Pb(II) hydride isomers is studied together with their (1)H NMR chemical shifts, which are predicted in the high-frequency region, up to 90 ppm. These (1)H signals are dictated by sizable relativistic contributions due to spin-orbit coupling at the heavy atom and can be as large as 80 ppm for a hydrogen atom bound to Pb(II). Such high-frequency (1)H NMR chemical shifts of Pb(II) hydride resonances cannot be detected in the (1)H NMR spectra with standard experimental setup. Extended (1)H NMR spectral ranges are thus suggested for studies of Pb(II) compounds. Modulation of spin-orbit relativistic contribution to (1)H NMR chemical shift is found to be important also in the experimentally known Sn(II) hydrides. Because the (1)H NMR chemical shifts were found to be rather sensitive to the changes in the coordination sphere of the central metal in both Sn(II) and Pb(II) hydrides, their application for structural investigation is suggested.

  20. High accuracy NMR chemical shift corrected for bulk magnetization as a tool for structural elucidation of dilutable microemulsions. Part 1 - Proof of concept.

    Science.gov (United States)

    Hoffman, Roy E; Darmon, Eliezer; Aserin, Abraham; Garti, Nissim

    2016-02-01

    In microemulsions, changes in droplet size and shape and possible transformations occur under various conditions. They are difficult to characterize by most analytical tools because of their nano-sized structure and dynamic nature. Several methods are usually combined to obtain reliable information, guiding the scientist in understanding their physical behavior. We felt that there is a need for a technique that complements those in use today in order to provide more information on the microemulsion behavior, mainly as a function of dilution with water. The improvement of NMR chemical shift measurements independent of bulk magnetization effects makes it possible to study the very weak intermolecular chemical shift effects. In the present study, we used NMR high resolution magic angle spinning to measure the chemical shift very accurately, free of bulk magnetization effects. The chemical shift of microemulsion components is measured as a function of the water content in order to validate the method in an interesting and promising, U-type dilutable microemulsion, which had been previously studied by a variety of techniques. Phase transition points of the microemulsion (O/W, bicontinuous, W/O) and changes in droplet shape were successfully detected using high-accuracy chemical shift measurements. We analyzed the results and found them to be compatible with the previous studies, paving the way for high-accuracy chemical shifts to be used for the study of other microemulsion systems. We detected two transition points along the water dilution line of the concentrate (reverse micelles) corresponding to the transition from swollen W/O nano-droplets to bicontinuous to the O/W droplets along with the changes in the droplets' sizes and shapes. The method seems to be in excellent agreement with other previously studied techniques and shows the advantage of this easy and valid technique.

  1. Intermolecular Interactions in Crystalline Theobromine as Reflected in Electron Deformation Density and (13)C NMR Chemical Shift Tensors.

    Science.gov (United States)

    Bouzková, Kateřina; Babinský, Martin; Novosadová, Lucie; Marek, Radek

    2013-06-11

    An understanding of the role of intermolecular interactions in crystal formation is essential to control the generation of diverse crystalline forms which is an important concern for pharmaceutical industry. Very recently, we reported a new approach to interpret the relationships between intermolecular hydrogen bonding, redistribution of electron density in the system, and NMR chemical shifts (Babinský et al. J. Phys. Chem. A, 2013, 117, 497). Here, we employ this approach to characterize a full set of crystal interactions in a sample of anhydrous theobromine as reflected in (13)C NMR chemical shift tensors (CSTs). The important intermolecular contacts are identified by comparing the DFT-calculated NMR CSTs for an isolated theobromine molecule and for clusters composed of several molecules as selected from the available X-ray diffraction data. Furthermore, electron deformation density (EDD) and shielding deformation density (SDD) in the proximity of the nuclei involved in the proposed interactions are calculated and visualized. In addition to the recently reported observations for hydrogen bonding, we focus here particularly on the stacking interactions. Although the principal relations between the EDD and CST for hydrogen bonding (HB) and stacking interactions are similar, the real-space consequences are rather different. Whereas the C-H···X hydrogen bonding influences predominantly and significantly the in-plane principal component of the (13)C CST perpendicular to the HB path and the C═O···H hydrogen bonding modulates both in-plane components of the carbonyl (13)C CST, the stacking modulates the out-of-plane electron density resulting in weak deshielding (2-8 ppm) of both in-plane principal components of the CST and weak shielding (∼ 5 ppm) of the out-of-plane component. The hydrogen-bonding and stacking interactions may add to or subtract from one another to produce total values observed experimentally. On the example of theobromine, we demonstrate

  2. Reproducibility of Intra- and Inter-scanner Measurements of Liver Fat Using Complex Confounder-corrected Chemical Shift Encoded MRI at 3.0 Tesla

    Science.gov (United States)

    Wu, Bing; Han, Wei; Li, Zhenhong; Zhao, Yonghua; Ge, Mingmei; Guo, Xueqing; Wu, Xinhuai

    2016-01-01

    The purpose of this study was to prospectively evaluate the reproducibility of the proton density fat-fraction (PDFF) of the liver using the IDEAL algorithm, a quantitative confounder-corrected chemical-shift-encoded MRI method. Data were obtained from 15 volunteers on four different days. The first and the third examinations were conducted on scanner one with one-week intervals, while the second and the fourth tests were performed on scanner two with same time interval. For each test, two MR scans were performed, one before and one after a meal. Regions-of-interest measurements were manually calculated to estimate the PDFF in the right and left lobes on the PDFF images. Reproducibility was measured using the intra-class correlation coefficient (ICC). The ICCs of the PDFF in the right and left lobes were 0.935 and 0.878, respectively. The intra-scanner ICCs of the right lobe before and after a meal or at a one-week interval were 0.924 and 0.953, respectively. The inter-scanner ICCs of PDFF the next day and at a one-week interval were 0.920 and 0.864, respectively. The PDFF of liver derived from IDEAL demonstrated high intra- and inter-scanner measurement reproducibility. The PDFF of the right lobe before a meal was more reproducible than after-meal measurements. PMID:26763303

  3. Shifting Phases for Patchy Particles - Effect of mutagenesis and chemical modification on the phase diagram of human gamma D crystallin

    Science.gov (United States)

    McManus, Jennifer J.; James, Susan; McNamara, Ruth; Quinn, Michelle

    2014-03-01

    Single mutations in human gamma D crystallin (HGD), a protein found in the eye lens are associated with several childhood cataracts. Phase diagrams for several of these protein mutants have been measured and reveal that phase boundaries are shifted compared with the native protein, leading to condensation of protein in a physiologically relevant regime. Using HGD as a model protein, we have constructed phase diagrams for double mutants of the protein, incorporating two single amino acid substitutions for which phase diagrams are already known. In doing so, the characteristics of each of the single mutations are maintained but both are now present in the same protein particle. While these proteins are not of interest physiologically, this strategy allows the controlled synthesis of nano-scale patchy particles in which features associated with a known phase behavior can be included. It can also provide a strategy for the controlled crystallisation of proteins. Phase boundaries also change after the chemical modification of the protein, through the covalent attachment of fluorescent labels, for example, and this will also be discussed. The authors acknowledge Science Foundation Ireland Stokes Lectureship and Grant 11/RFP.1/PHY/3165. The authors also acknowledge the Irish Research Council and the John and Pat Hume Scholarship.

  4. Molecular structure and vibrational and chemical shift assignments of 3'-chloro-4-dimethylamino azobenzene by DFT calculations.

    Science.gov (United States)

    Toy, Mehmet; Tanak, Hasan

    2016-01-05

    In the present work, a combined experimental and theoretical study on ground state molecular structure, spectroscopic and nonlinear optical properties of azo compound 3'-chloro-4-dimethlamino azobenzene are reported. The molecular geometry, vibrational wavenumbers and the first order hyperpolarizability of the title compound were calculated with the help of density functional theory computations. The optimized geometric parameters obtained by using DFT (B3LYP/6-311++G(d,p)) show good agreement with the experimental data. The vibrational transitions were identified based on the recorded FT-IR spectra in the range of 4000-400cm(-1) for solid state. The (1)H isotropic chemical shifts with respect to TMS were also calculated using the gauge independent atomic orbital (GIAO) method and compared with the experimental data. Using the TD-DFT method, electronic absorption spectra of the title compound have been predicted, and good agreement is determined with the experimental ones. To investigate the NLO properties of the title compound, the polarizability and the first hyperpolarizability were calculated using the density functional B3LYP method with the 6-311++G(d,p) basis set. According to results, the title compound exhibits non-zero first hyperpolarizability value revealing second order NLO behavior. In addition, DFT calculations of the title compound, molecular electrostatic potential and frontier molecular orbitals were also performed at 6-311++G(d,p) level of theory.

  5. Chemical shifts assignments of the archaeal MC1 protein and a strongly bent 15 base pairs DNA duplex in complex.

    Science.gov (United States)

    Loth, Karine; Landon, Céline; Paquet, Françoise

    2015-04-01

    MC1 is the most abundant architectural protein present in Methanosarcina thermophila CHTI55 in laboratory growth conditions and is structurally unrelated to other DNA-binding proteins. MC1 functions are to shape and to protect DNA against thermal denaturation by binding to it. Therefore, MC1 has a strong affinity for any double-stranded DNA. However, it recognizes and preferentially binds to bent DNA, such as four-way junctions and negatively supercoiled DNA minicircles. Combining NMR data, electron microscopy data, biochemistry, molecular modelisation and docking approaches, we proposed recently a new type of DNA/protein complex, in which the monomeric protein MC1 binds on the concave side of a strongly bent 15 base pairs DNA. We present here the NMR chemical shifts assignments of each partner in the complex, (1)H (15)N MC1 protein and (1)H (13)C (15)N bent duplex DNA, as first step towards the first experimental 3D structure of this new type of DNA/protein complex.

  6. Fragment-Based Approach for the Evaluation of NMR Chemical Shifts for Large Biomolecules Incorporating the Effects of the Solvent Environment.

    Science.gov (United States)

    Jose, K V Jovan; Raghavachari, Krishnan

    2017-03-14

    We present an efficient implementation of the molecules-in-molecules (MIM) fragment-based quantum chemical method for the evaluation of NMR chemical shifts of large biomolecules. Density functional techniques have been employed in conjunction with large basis sets and including the effects of the solvent environment in these calculations. The MIM-NMR method is initially benchmarked on a set of (alanine)10 conformers containing strong intramolecular interactions. The incorporation of a second low level of theory to recover the missing long-range interactions in the primary fragmentation scheme is critical to yield reliable chemical shifts, with a mean absolute deviation (MAD) from direct unfragmented calculations of 0.01 ppm for (1)H chemical shifts and 0.07 ppm for (13)C chemical shifts. In addition, the performance of MIM-NMR has been assessed on two large peptides: the helical portion of ubiquitin ( 1UBQ ) containing 12 residues where the X-ray structure is known, and E6-binding protein of papilloma virus ( 1RIJ ) containing 23 residues where the structure has been derived from solution-phase NMR analysis. The solvation environment is incorporated in these MIM-NMR calculations, either through an explicit, implicit, or a combination of both solvation models. Using an explicit treatment of the solvent molecules within the first solvation sphere (3 Å) and an implicit solvation model for the rest of the interactions, the (1)H and (13)C chemical shifts of ubiquitin show excellent agreement with experiment (mean absolute deviation of 0.31 ppm for (1)H and 1.72 ppm for (13)C), while the larger E6-binding protein yields a mean absolute deviation of 0.34 ppm for (1)H chemical shifts. The proposed MIM-NMR method is computationally cost-effective and provides a substantial speedup relative to conventional full calculations, the largest density functional NMR calculation included in this work involving more than 600 atoms and over 10,000 basis functions. The MIM

  7. Chemical shift as a probe of molecular interfaces: NMR studies of DNA binding by the three amino-terminal zinc finger domains from transcription factor IIIA

    Energy Technology Data Exchange (ETDEWEB)

    Foster, Mark P.; Wuttke, Deborah S.; Clemens, Karen R.; Jahnke, Wolfgang; Radhakrishnan, Ishwar; Tennant, Linda; Reymond, Martine; Chung, John; Wright, Peter E. [Scripps Research Institute, Department of Molecular Biology and Skaggs Institute for Chemical Biology (United States)

    1998-07-15

    We report the NMR resonance assignments for a macromolecular protein/DNA complex containing the three amino-terminal zinc fingers (92 amino acid residues) of Xenopus laevis TFIIIA (termed zf1-3) bound to the physiological DNA target (15 base pairs), and for the free DNA. Comparisons are made of the chemical shifts of protein backbone{sup 1} H{sup N}, {sup 15}N,{sup 13} C{sup {alpha}} and{sup 13} C{sup {beta}} and DNA base and sugar protons of the free and bound species. Chemical shift changes are analyzed in the context of the structures of the zf1-3/DNA complex to assess the utility of chemical shift change as a probe of molecular interfaces. Chemical shift perturbations that occur upon binding in the zf1-3/DNA complex do not correspond directly to the structural interface, but rather arise from a number of direct and indirect structural and dynamic effects.

  8. Correlation between dynamic wetting behavior and chemical components of thermally modified wood

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Wang; Zhu, Yuan; Cao, Jinzhen, E-mail: caoj@bjfu.edu.cn; Sun, Wenjing

    2015-01-01

    Highlights: • We studied the dynamic wetting behavior of thermally modified wood by wetting models. • We found lower wetting speed of water droplets on thermally modified wood surface. • Dynamic wetting behavior and surface chemical components show a strong correlation. - Abstract: In order to investigate the dynamic wetting behavior of thermally modified wood, Cathay poplar (Populus cathayana Rehd.) and Scots pine (Pinus sylvestris L.) samples were thermally modified in an oven at 160, 180, 200, 220 or 240 °C for 4 h in this study. The dynamic contact angles and droplet volumes of water droplets on modified and unmodified wood surfaces were measured by sessile drop method, and their changing rates (expression index: K value and wetting slope) calculated by wetting models were illustrated for mapping the dynamic wetting process. The surface chemical components were also measured by X-ray photoelectron spectroscopy analysis (XPS), thus the relationship between dynamic wetting behavior and chemical components of thermally modified wood were determined. The results indicated that thermal modification was capable of decreasing the dynamic wettability of wood, expressed in lowing spread and penetration speed of water droplets on wood surfaces. This change was more obvious with the increased heating temperature. The K values varied linearly with the chemical components parameter (mass loss, O/C ratio, and C{sub 1}/C{sub 2} ratio), indicating a strong correlation between dynamic wetting behavior and chemical components of thermally modified wood.

  9. Chemical shift of U L3 edges in different uranium compounds obtained by X-ray absorption spectroscopy with synchrotron radiation

    Indian Academy of Sciences (India)

    D Joseph; C Nayak; P Venu Babu; S N Jha; D Bhattacharyya

    2014-05-01

    Uranium L3 X-ray absorption edge was measured in various compounds containing uranium in U4+, U5+ and U6+ oxidation states. The measurements have been carried out at the Energy Dispersive EXAFS beamline (BL-08) at INDUS-2 synchrotron radiation source at RRCAT, Indore. Energy shifts of ∼ 2–3 eV were observed for U L3 edge in the U-compounds compared to their value in elemental U. The different chemical shifts observed for the compounds having the same oxidation state of the cation but different anions or ligands show the effect of different chemical environments surrounding the cations in determining their X-ray absorption edges in the above compounds. The above chemical effect has been quantitatively described by determining the effective charges on U cation in the above compounds.

  10. Combining ambiguous chemical shift mapping with structure-based backbone and NOE assignment from 15N-NOESY

    KAUST Repository

    Jang, Richard

    2011-01-01

    Chemical shift mapping is an important technique in NMRbased drug screening for identifying the atoms of a target protein that potentially bind to a drug molecule upon the molecule\\'s introduction in increasing concentrations. The goal is to obtain a mapping of peaks with known residue assignment from the reference spectrum of the unbound protein to peaks with unknown assignment in the target spectrum of the bound protein. Although a series of perturbed spectra help to trace a path from reference peaks to target peaks, a one-to-one mapping generally is not possible, especially for large proteins, due to errors, such as noise peaks, missing peaks, missing but then reappearing, overlapped, and new peaks not associated with any peaks in the reference. Due to these difficulties, the mapping is typically done manually or semi-automatically. However, automated methods are necessary for high-throughput drug screening. We present PeakWalker, a novel peak walking algorithm for fast-exchange systems that models the errors explicitly and performs many-to-one mapping. On the proteins: hBclXL, UbcH5B, and histone H1, it achieves an average accuracy of over 95% with less than 1.5 residues predicted per target peak. Given these mappings as input, we present PeakAssigner, a novel combined structure-based backbone resonance and NOE assignment algorithm that uses just 15N-NOESY, while avoiding TOCSY experiments and 13C- labeling, to resolve the ambiguities for a one-toone mapping. On the three proteins, it achieves an average accuracy of 94% or better. Copyright © 2011 ACM.

  11. Correlation between the band gap, elastic modulus, Raman shift and melting point of CdS, ZnS, and CdSe semiconductors and their size dependency

    Science.gov (United States)

    Yang, C.; Zhou, Z. F.; Li, J. W.; Yang, X. X.; Qin, W.; Jiang, R.; Guo, N. G.; Wang, Y.; Sun, C. Q.

    2012-02-01

    With structural miniaturization down to the nanoscale, the detectable quantities of solid materials no longer remain constant but become tunable. For the II-VI semiconductors example, the band gap expands, the elastic modulus increases, the melting point drops, and the Raman optical phonons experience red shift associated with creation of low frequency Raman acoustic modes that undergo blue shift with decreasing the dimensional scale. In order to understand the common origin of the size dependency of these seemingly irrelevant properties, we formulated these quantities for CdS, ZnS, and CdSe semiconductors from the perspectives of bond order-length-strength correlation and the local bond averaging approach. Consistency between the theory predictions and the measured size dependence of these quantities clarified that the undercoordination-induced local strain and quantum entrapment and the varied fraction of undercoordinated atoms of the entire solid correlate these quantities and dominate their size effect.

  12. Phase-shifting of correlation fringes created by image processing as an alternative to improve digital shearography

    Science.gov (United States)

    Braga, Roberto A.; González-Peña, Rolando J.; Marcon, Marlon; Magalhães, Ricardo R.; Paiva-Almeida, Thiago; Santos, Igor V. A.; Martins, Moisés

    2016-12-01

    The adoption of digital speckle pattern shearing interferometry, or speckle shearography, is well known in many areas when one needs to measure micro-displacements in-plane and out of the plane in biological and non-biological objects; it is based on the Michelson's Interferometer with the use of a piezoelectric transducer (PZT) in order to provide the phase-shift of the fringes and then to improve the quality of the final image. The creation of the shifting images using a PZT, despite its widespread use, has some drawbacks or limitations, such as the cost of the apparatus, the difficulties in applying the same displacement in the mirror repeated times, and when the phase-shift cannot be used in dynamic object measurement. The aim of this work was to create digitally phase-shift images avoiding the mechanical adjustments of the PZT, testing them with the digital shearography method. The methodology was tested using a well-known object, a cantilever beam of aluminium under deformation. The results documented the ability to create the deformation map and curves with reliability and sensitivity, reducing the cost, and improving the robustness and also the accessibility of digital speckle pattern shearing interferometry.

  13. Correlation of Chemical and Physical Test Data for the Environmental Ageing of Tefzel (ETFE). Revised

    Science.gov (United States)

    Morgan, G. J.; Campion, R. P.

    1997-01-01

    In a similar approach to that used for the previously issued correlation report for Coflon (CAPP/M.10), this report aims to identify any correlations between mechanical property changes and chemical/morphological changes for Tefzel, using information supplied in other MERL and TRI project reports. Differences identified with Coflon behaviour will be of scientific interest as well as appropriate to project applications, as Tefzel and Coflon are chemical isomers. Owing to the considerable chemical resistance of Tefzel, much of its testing so far has been based on mechanical properties. Where changes have occurred, chemical analysis can now be targeted more effectively. Relevant test data collated here include: tensile modulus and related properties, permeation coefficients, % crystallinity, some crack growth resistance measurements, and other observations where significant. Fluids based on methanol and amine (Fluid G), a mixture of methane, carbon dioxide and hydrogen sulphide gases plus an aqueous amine solution (Fluid F), and an aromatic oil mix of heptane, cyclohexane, toluene and 1-propanol (Fluid I) have affected Tefzel to varying degrees, and are discussed in some detail herein.

  14. Correlation of Chemical and Physical Test Data for the Environmental Ageing of Tefzel (ETFE)

    Science.gov (United States)

    Morgan, G. J.; Campion, R. P.

    1996-01-01

    In a similar approach to that used for the previously issued correlation report for Coflon (CAPP/M.10), this report aims to identify any correlations between mechanical property changes and chemical/morphological changes for Tefzel, using information supplied in other MERL and TRI project reports (plus latest data which will be included in final reports for Phase 1). Differences identified with Coflon behaviour will be of scientific interest as well as appropriate to project applications, as Tefzel and Coflon are chemical isomers. Owing to the considerable chemical resistance of Tefzel, much of its testing so far has been based on mechanical properties. Where changes have occurred, chemical analysis can now be targeted more effectively. Relevant test data collated here include: tensile modulus and related properties, permeation coefficients, % crystallinity, and other observations where significant. Fluids based on methanol and amine (Fluid G), a mixture of methane, carbon dioxide and hydrogen sulphide gases plus an aqueous amine solution (Fluid F), and an aromatic oil mix of heptane, cyclohexane, toluene and I-propanol (Fluid 1) have affected Tefzel to varying degrees, and are discussed in some detail herein.

  15. Evaluation of correlation between chemical dosimetry and subharmonic spectrum analysis to examine the acoustic cavitation.

    Science.gov (United States)

    Hasanzadeh, Hadi; Mokhtari-Dizaji, Manijhe; Bathaie, S Zahra; Hassan, Zuhair M

    2010-06-01

    Currently several therapeutic applications of ultrasound in cancer treatment are under progress which uses cavitation phenomena to deliver their effects. There are several methods to evaluate cavitation activity such as chemical dosimetry and measurement of subharmonic signals. In this study, the cavitation activity induced by the ultrasound irradiation on exposure parameters has been measured by terephthalic acid chemical dosimetry and subharmonic analysis. Experiments were performed in the near 1 MHz fields in the progressive wave mode and effect of duty cycles changes with 2 W/cm(2) intensity (I(SATA)) and acoustic intensity changes in continuous mode on both fluorescence intensity and subharmonic intensity were measured. The dependence between fluorescence intensity of terephthalic acid chemical dosimetry and subharmonic intensity analysis were analyzed by Pearson correlation (p-value subharmonic intensity and the fluorescence intensity for continuous mode is higher than for pulsing mode (p-value subharmonic intensity and the fluorescence intensity with sonication intensity (p-value subharmonic intensity at different duty cycles (R=0.997, p-value subharmonic intensity (microW/cm(2)) significantly correlated with the fluorescence intensity (count) (R=0.901; psubharmonic intensity due to subharmonic spectrum analysis. It is concluded that there is dependence between terephthalic acid chemical dosimetry and subharmonic spectrum analysis to examine the acoustic cavitation activity.

  16. COSMO-RSC: Second-Order Quasi-Chemical Theory Recovering Local Surface Correlation Effects.

    Science.gov (United States)

    Klamt, A

    2016-03-31

    The conductor-like screening model for realistic solvation (COSMO-RS) was introduced 20 years ago and meanwhile has become an important tool for the prediction of fluid phase equilibrium properties. Starting from quantum chemical information about the surface polarity of solutes and solvents, it solves the statistical thermodynamics of molecules in liquid phases by the very efficient approximation of independently pairwise interacting surfaces, which meanwhile was shown to be equivalent to Guggenheim's quasi-chemical theory. One of the basic limitations of COSMO-RS, as of any quasi-chemical model, is the neglect of neighbor information, i.e., of local correlations of surface types on the molecular surface. In this paper we present the completely novel concept of using the first-order COSMO-RS contact probabilities for the construction of local surface correlation functions. These are fed as an entropic correction for the pair interactions into a second COSMO-RS self-consistency loop, which yields new contact probabilities, enthalpies, free energies and activity coefficients recovering much of the originally lost neighbor effects. By a novel analytic correction for concentration dependent interactions, the resulting activity coefficients remain exactly Gibbs-Duhem consistent. The theory is demonstrated on the example of a lattice Monte Carlo fluid of dimerizing pseudomolecules. In this showcase the strong deviations of the lattice Monte Carlo fluid from quasi-chemical theory are almost perfectly reproduced by COSMO-RSC.

  17. Relativistic four-component DFT calculations of 1H NMR chemical shifts in transition-metal hydride complexes: unusual high-field shifts beyond the Buckingham-Stephens model.

    Science.gov (United States)

    Hrobárik, Peter; Hrobáriková, Veronika; Meier, Florian; Repiský, Michal; Komorovský, Stanislav; Kaupp, Martin

    2011-06-09

    State-of-the-art relativistic four-component DFT-GIAO-based calculations of (1)H NMR chemical shifts of a series of 3d, 4d, and 5d transition-metal hydrides have revealed significant spin-orbit-induced heavy atom effects on the hydride shifts, in particular for several 4d and 5d complexes. The spin-orbit (SO) effects provide substantial, in some cases even the dominant, contributions to the well-known characteristic high-field hydride shifts of complexes with a partially filled d-shell, and thereby augment the Buckingham-Stephens model of off-center paramagnetic ring currents. In contrast, complexes with a 4d(10) and 5d(10) configuration exhibit large deshielding SO effects on their hydride (1)H NMR shifts. The differences between the two classes of complexes are attributed to the dominance of π-type d-orbitals for the true transition-metal systems compared to σ-type orbitals for the d(10) systems.

  18. Solvent-induced chemical shifts of methoxyl nuclear resonance signals in chalcones by benzene and trifluoroacetic acid

    Science.gov (United States)

    Khurana, Shashi K.; Krishnamoorthy, V.; Parmar, Virinder S.

    The 1H NMR spectra of eight different methoxylated chalcones have separately been recorded, (1) in deuterated chloroform; (2) in a mixture (1:1) of deuterated chloroform and benzene; and (3) in a mixture of deuterated chloroform, benzene and trifluoroacetic acid (2:2:1) and the benzene induced and TFA induced shift values have been assigned to different methoxyl groups. These shift values can serve as a guide in determining the structures of natural or new chalcones. The steric, electronic and conformational factors are discussed to explain the shift values.

  19. Precision Measurement of the Quadrupole Coupling and Chemical Shift Tensors of the Deuterons in α-Calcium Formate

    Science.gov (United States)

    Schmitt, Heike; Zimmermann, H.; Körner, O.; Stumber, M.; Meinel, C.; Haeberlen, U.

    2001-07-01

    Using calcium formate, α-Ca(DCOO)2, as a test sample, we explore how precisely deuteron quadrupole coupling (QC) and chemical shift (CS) tensors Q and σ can currently be measured. The error limits, ±0.09 kHz for the components of Q and ±0.06 ppm for those of σ, are at least three times lower than in any comparable previous experiment. The concept of a new receiver is described. A signal/noise ratio of 100 is realized in single-shot FT spectra. The measurement strategies and a detailed error analysis are presented. The precision of the measurement of Q is limited by the uncertainty of the rotation angles of the sample and that of σ by the uncertainty of the phase correction parameters needed in FT spectroscopy. With a 4-sigma confidence, it is demonstrated for the first time that the unique QC tensor direction of a deuteron attached to a carbon deviates from the bond direction; the deviation found is (1.2±0.3°). Evidence is provided for intermolecular QC contributions. In terms of Q, their size is roughly 4 kHz. The deuteron QC tensors in α-Ca(DCOO)2 (two independent deuteron sites) are remarkable in three respects. For deuterons attached to sp2 carbons, first, the asymmetry factors η and, second, the quadrupole coupling constants CQ, are unusually small, η1=0.018, η2=0.011, and CQ1=(151.27±0.06) kHz, CQ2=(154.09±0.06) kHz. Third, the principal direction associated with the largest negative QC tensor component lies in and not, as usual, perpendicular to the molecular plane. A rationalization is provided for these observations. The CS tensors obtained are in quantitative agreement with the results of an earlier, less precise, line-narrowing multiple-pulse study of α-Ca(HCOO)2. The assignment proposed in that work is confirmed. Finally we argue that a further 10-fold increase of the measurement precision of deuteron QC tensors, and a 2-fold increase of that of CS tensors, should be possible. We indicate the measures that need to be taken.

  20. Detection of chemical vapor with high sensitivity by using the symmetrical metal-cladding waveguide-enhanced Goos-Hänchen shift.

    Science.gov (United States)

    Nie, Yiyou; Li, Yuanhua; Wu, Zhijing; Wang, Xianping; Yuan, Wen; Sang, Minghuang

    2014-04-21

    We present a novel and simple optical structure, i.e., the symmetrical metal-cladding waveguide, in which a polymer layer is added into the guiding layer, for sensitive detection of chemical vapor by using the enhanced Goos-Hänchen (GH) shift (nearly a millimeter scale). Owing to the high sensitivity of the excited ultrahigh-order modes, the vapor-induced effect (swelling effect and refractive index change) in the polymer layer will lead to a dramatic variation of the GH shift. The detected GH shift signal is irrelevant to the power fluctuation of the incident light. The detection limit of 9.5 ppm for toluene and 28.5 ppm for benzene has been achieved.

  1. Chemical shifts of K-X-ray absorption edges on copper in different compounds by X-ray absorption spectroscopy (XAS) with Synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Joseph, D., E-mail: djoseph@barc.gov.in [Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Basu, S.; Jha, S.N.; Bhattacharyya, D. [Applied Spectroscopy Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2012-03-01

    Cu K X-ray absorption edges were measured in compounds such as CuO, Cu(CH{sub 3}CO{sub 2}){sub 2}, Cu(CO{sub 3}){sub 2}, and CuSO{sub 4} where Cu is present in oxidation state of 2+, using the energy dispersive EXAFS beamline at INDUS-2 Synchrotron radiation source at RRCAT, Indore. Energy shifts of {approx}4-7 eV were observed for Cu K X-ray absorption edge in the above compounds compared to its value in elemental copper. The difference in the Cu K edge energy shifts in the different compounds having same oxidation state of Cu shows the effect of different chemical environments surrounding the cation in the above compounds. The above chemical effect has been quantitatively described by determining the effective charges on Cu cations in the above compounds.

  2. Chemical shifts of K-X-ray absorption edges on copper in different compounds by X-ray absorption spectroscopy (XAS) with Synchrotron radiation

    Science.gov (United States)

    Joseph, D.; Basu, S.; Jha, S. N.; Bhattacharyya, D.

    2012-03-01

    Cu K X-ray absorption edges were measured in compounds such as CuO, Cu(CH3CO2)2, Cu(CO3)2, and CuSO4 where Cu is present in oxidation state of 2+, using the energy dispersive EXAFS beamline at INDUS-2 Synchrotron radiation source at RRCAT, Indore. Energy shifts of ˜4-7 eV were observed for Cu K X-ray absorption edge in the above compounds compared to its value in elemental copper. The difference in the Cu K edge energy shifts in the different compounds having same oxidation state of Cu shows the effect of different chemical environments surrounding the cation in the above compounds. The above chemical effect has been quantitatively described by determining the effective charges on Cu cations in the above compounds.

  3. Repeatability, correlation and path analysis of physical and chemical characteristics of peach fruits

    Directory of Open Access Journals (Sweden)

    Rosana Gonçalves Pires Matias

    2014-12-01

    Full Text Available This study aimed to determine the number of measurements necessary to evaluate physical and chemical characteristics of peach fruits, study the relationships between them and their direct and indirect effects on the content of ascorbic acid and total carotenoids. The characteristics skin and pulp color, fruit weight, suture, equatorial and polar diameters, firmness, soluble solids (SS, titratable acidity (TA, SS/TA ratio, ascorbic acid and total carotenoids were evaluated in 39 cultivars of peach and 3 cultivars of nectarine from the orchard of the Universidade Federal de Viçosa. The repeatability coefficient was estimated by ANOVA and CPCOR. Phenotypic correlation coefficients (rf were estimated and, after the multicollinearity diagnostics, they were unfolded to direct and indirect effects of the explanatory variables on the response variable using path analysis. There was agreement on the magnitude of repeatability coefficients obtained by the two methods; however, they varied among the 14 characteristics. The highest correlations were found between FW, SD, ED and PD. Seven fruits are sufficient to evaluate the physical and chemical characteristics of peach with a correlation coefficient of 90%. The characteristics considered in the path diagrams (b* skin, hº skin, b* pulp, hº pulp, ED, PD, FIR, SS, SS/AT and TC are not the main determinants of the ascorbic acid. The yellow hue of the pulp (hº pulp has the potential to be used in indirect selection for total carotenoids.

  4. Free magnesium levels in normal human brain and brain tumors: sup 31 P chemical-shift imaging measurements at 1. 5 T

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, J.S.; Vigneron, D.B.; Murphy-Boesch, J.; Nelson, S.J.; Kessler, H.B.; Coia, L.; Curran, W.; Brown, T.R. (Fox Chase Cancer Center, Philadelphia, PA (United States))

    1991-08-01

    The authors have studied a series of normal subjects and patients with brain tumors, by using {sup 31}P three-dimensional chemical shift imaging to obtain localized {sup 31}P spectra of the brain. A significant proportion of brain cytosolic ATP in normal brain is not complexed to Mg{sup 2+}, as indicated by the chemical shift {delta} of the {beta}-P resonance of ATP. The ATP {beta}P resonance position in brain thus is sensitive to changes in intracellular free Mg{sup 2+} concentration and in the proportion of ATP complexed with Mg because this shift lies on the rising portion of the {delta} vs. Mg{sup 2+} titration curve for ATP. They have measured the ATP {beta}-P shift and compared intracellular free Mg{sup 2+} concentration and fractions of free ATP for normal individuals and a limited series of patients with brain tumors. In four of the five spectra obtained from brain tissue containing a substantial proportion of tumor, intracellular free Mg{sup 2+} was increased, and the fraction of free ATP was decreased, compared with normal brain.

  5. Evidence of chemical-potential shift with hole doping in Bi sub 2 Sr sub 2 CaCu sub 2 O sub 8+. delta

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Z.; Dessau, D.S.; Wells, B.O. (Stanford Electronics Laboratory, Stanford University, Stanford, California 94305 (United States)); Olson, C.G. (Ames Laboratory, Iowa State University, Ames, Iowa 50011 (United States)); Mitzi, D.B.; Lombado, L. (Department of Applied Physics, Stanford University, Stanford, California 94305 (United States)); List, R.S.; Arko, A.J. (Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States))

    1991-12-01

    We have performed photoemission studies on high-quality Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} samples with various {delta}. Our results show a clear chemical-potential shift (0.15--0.2 eV) as a function of doping. This result and the existing angle-resolved-photoemission data give a rather standard doping behavior of this compound in its highly doped regime.

  6. Progress in spin dynamics solid-state nuclear magnetic resonance with the application of Floquet-Magnus expansion to chemical shift anisotropy.

    Science.gov (United States)

    Mananga, Eugene Stephane

    2013-01-01

    The purpose of this article is to present an historical overview of theoretical approaches used for describing spin dynamics under static or rotating experiments in solid state nuclear magnetic resonance. The article gives a brief historical overview for major theories in nuclear magnetic resonance and the promising theories. We present the first application of Floquet-Magnus expansion to chemical shift anisotropy when irradiated by BABA pulse sequence.

  7. Correlation between dynamic wetting behavior and chemical components of thermally modified wood

    Science.gov (United States)

    Wang, Wang; Zhu, Yuan; Cao, Jinzhen; Sun, Wenjing

    2015-01-01

    In order to investigate the dynamic wetting behavior of thermally modified wood, Cathay poplar (Populus cathayana Rehd.) and Scots pine (Pinus sylvestris L.) samples were thermally modified in an oven at 160, 180, 200, 220 or 240 °C for 4 h in this study. The dynamic contact angles and droplet volumes of water droplets on modified and unmodified wood surfaces were measured by sessile drop method, and their changing rates (expression index: K value and wetting slope) calculated by wetting models were illustrated for mapping the dynamic wetting process. The surface chemical components were also measured by X-ray photoelectron spectroscopy analysis (XPS), thus the relationship between dynamic wetting behavior and chemical components of thermally modified wood were determined. The results indicated that thermal modification was capable of decreasing the dynamic wettability of wood, expressed in lowing spread and penetration speed of water droplets on wood surfaces. This change was more obvious with the increased heating temperature. The K values varied linearly with the chemical components parameter (mass loss, O/C ratio, and C1/C2 ratio), indicating a strong correlation between dynamic wetting behavior and chemical components of thermally modified wood.

  8. All-atom Molecular Dynamic Simulations Combined with the Chemical Shifts Study on the Weak Interactions of Ethanol-water System

    Institute of Scientific and Technical Information of China (English)

    ZHANG Rong; LUO San-Lai; WU Wen-Juan

    2008-01-01

    All-atom molecular dynamics(MD)simulation combined with chemical shifts was performed to investigate the interactions over the entire concentration range of the ethanol(EtOH)-water system.The results of the simulation were adopted to explain the NMR experiments by hydrogen bonding analysis.The strong hydrogen bonds and weak C-H…O contacts coexist in the mixtures through the analysis of the radial distribution functions.And the liquid structures in the whole concentration of EtOH-water mixtures can be classified into three regions by the statistic analysis of the hydrogen-bonding network in the MD simulations.Moreover,the chemical shifts of the hydrogen atom are in agreement witb the statistical results of the average number hydrogen bonds in the MD simulations.Interestingly,the excess relative extent Eηrel calculated by the MD simulations and chemical shifts in the EtOH aqueous solutions shows the largest deviation at XEtOH≈0.18.The excess properties present good agreement with the excess enthalpy in the concentration dependence.

  9. CSI 3.0: a web server for identifying secondary and super-secondary structure in proteins using NMR chemical shifts.

    Science.gov (United States)

    Hafsa, Noor E; Arndt, David; Wishart, David S

    2015-07-01

    The Chemical Shift Index or CSI 3.0 (http://csi3.wishartlab.com) is a web server designed to accurately identify the location of secondary and super-secondary structures in protein chains using only nuclear magnetic resonance (NMR) backbone chemical shifts and their corresponding protein sequence data. Unlike earlier versions of CSI, which only identified three types of secondary structure (helix, β-strand and coil), CSI 3.0 now identifies total of 11 types of secondary and super-secondary structures, including helices, β-strands, coil regions, five common β-turns (type I, II, I', II' and VIII), β hairpins as well as interior and edge β-strands. CSI 3.0 accepts experimental NMR chemical shift data in multiple formats (NMR Star 2.1, NMR Star 3.1 and SHIFTY) and generates colorful CSI plots (bar graphs) and secondary/super-secondary structure assignments. The output can be readily used as constraints for structure determination and refinement or the images may be used for presentations and publications. CSI 3.0 uses a pipeline of several well-tested, previously published programs to identify the secondary and super-secondary structures in protein chains. Comparisons with secondary and super-secondary structure assignments made via standard coordinate analysis programs such as DSSP, STRIDE and VADAR on high-resolution protein structures solved by X-ray and NMR show >90% agreement between those made with CSI 3.0.

  10. A Correlation Study on Physico-Chemical Characteristics of Dairy Wastewater

    Directory of Open Access Journals (Sweden)

    V. Karthikeyan

    2015-02-01

    Full Text Available The dairy industry has important to day-to- day in human life. Dairy industry involves processing of raw milk into products like milk, butter and cheese, etc., and generates 1 to 3 times the volume of milk produced. Knowledge on the physico-chemical characteristics of dairy wastewater is essential in the design, operation, collection and treatment as well as disposal facilities for the effective management of environmental quality. In this regard wastewater samples were collected from a dairy industry located in Thanjavur District, Tamilnadu and analyzed for various physico-chemical parameters. Most of the parameters exceed the permissible limits prescribed by the Central Pollution Control Board of India for discharging into surface waters. A correlation analysis has been carried out among various parameters. The analysis is terribly realistic in wastewater management as well as safe disposal strategies.

  11. Correlation between mechanical and chemical degradation after outdoor and accelerated laboratory aging for multilayer photovoltaic backsheets

    Science.gov (United States)

    Lin, Chiao-Chi; Lyu, Yadong; Yu, Li-Chieh; Gu, Xiaohong

    2016-09-01

    Channel cracking fragmentation testing and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy were utilized to study mechanical and chemical degradation of a multilayered backsheet after outdoor and accelerated laboratory aging. A model sample of commercial PPE backsheet, namely polyethylene terephthalate/polyethylene terephthalate/ethylene vinyl acetate (PET/PET/EVA) was investigated. Outdoor aging was performed in Gaithersburg, Maryland, USA for up to 510 days, and complementary accelerated laboratory aging was conducted on the NIST (National Institute of Standards and Technology) SPHERE (Simulated Photodegradation via High Energy Radiant Exposure). Fracture energy, mode I stress intensity factor and film strength were analyzed using an analytical model based on channel cracking fragmentation testing results. The correlation between mechanical and chemical degradation was discussed for both outdoor and accelerated laboratory aging. The results of this work provide preliminary understanding on failure mechanism of backsheets after weathering, laying the groundwork for linking outdoor and indoor accelerated laboratory testing for multilayer photovoltaic backsheets.

  12. Allometric shape change of the lower pharyngeal jaw correlates with a dietary shift to piscivory in a cichlid fish

    Science.gov (United States)

    Hellig, Christoph J.; Kerschbaumer, Michaela; Sefc, Kristina M.; Koblmüller, Stephan

    2010-07-01

    The morphological versatility of the pharyngeal jaw of cichlid fishes is assumed to represent a key factor facilitating their unparalleled trophic diversification and explosive radiation. It is generally believed that the functional design of an organism relates to its ecology, and thus, specializations to different diets are typically associated with distinct morphological designs, especially manifested in the cichlids’ pharyngeal jaw apparatus. Thereby, the lower pharyngeal jaw (LPJ) incorporates some of the most predictive features for distinct diet-related morphotypes. Thus, considering that piscivorous cichlids experience an ontogenetic dietary shift from typically various kinds of invertebrates to fish, concomitant morphological changes in the LPJ are expected. Using Lepidiolamprologus elongatus, a top predator in the shallow rocky habitat of Lake Tanganyika, as model, and applying geometric and traditional morphometric techniques, we demonstrate an allometric change in ontogenetic LPJ shape development coinciding with the completion of the dietary shift toward piscivory. The piscivorous LPJ morphotype is initiated in juvenile fish by increasing elongation and narrowing of the LPJ and—when the fish reach a size of 80-90 mm standard length—further refined by the elongation of the posterior muscular processes, which serve as insertion for the fourth musculus levator externus. The enlarged muscular processes of the fully mature piscivorous morphotype provide for the construction of a powerful lever system, which allows the large individuals to process large prey fish and rely on exclusive piscivory.

  13. A nonlinear training set superposition filter derived by neural network training methods for implementation in a shift-invariant optical correlator

    Science.gov (United States)

    Kypraios, Ioannis; Young, Rupert C. D.; Birch, Philip M.; Chatwin, Christopher R.

    2003-08-01

    The various types of synthetic discriminant function (sdf) filter result in a weighted linear superposition of the training set images. Neural network training procedures result in a non-linear superposition of the training set images or, effectively, a feature extraction process, which leads to better interpolation properties than achievable with the sdf filter. However, generally, shift invariance is lost since a data dependant non-linear weighting function is incorporated in the input data window. As a compromise, we train a non-linear superposition filter via neural network methods with the constraint of a linear input to allow for shift invariance. The filter can then be used in a frequency domain based optical correlator. Simulation results are presented that demonstrate the improved training set interpolation achieved by the non-linear filter as compared to a linear superposition filter.

  14. Double-echo gradient chemical shift MR imaging fails to differentiate minimal fat renal angiomyolipomas from other homogeneous solid renal tumors

    Energy Technology Data Exchange (ETDEWEB)

    Ferré, R., E-mail: kn638@yahoo.fr [Department of Radiology, Necker Hospital, 149 rue de Sèvres, 75730 Paris (France); Cornelis, F. [Department of Radiology, Pellegrin Hospital, Place Amélie Raba Léon, 33076 Bordeaux (France); Verkarre, V. [Department of Pathology, Necker Hospital, 149 rue de Sèvres, 75730 Paris (France); Eiss, D.; Correas, J.M. [Department of Radiology, Necker Hospital, 149 rue de Sèvres, 75730 Paris (France); Grenier, N. [Department of Radiology, Pellegrin Hospital, Place Amélie Raba Léon, 33076 Bordeaux (France); Hélénon, O. [Department of Radiology, Necker Hospital, 149 rue de Sèvres, 75730 Paris (France)

    2015-03-15

    Highlights: •Diagnosis of AMLs with minimal fat (mfAMLs) is still challenging with MRI. •Drop of signal on opposed-phase MR imaging is not specific of mfAMLs. •Double-echo gradient-echo sequences cannot accurately differentiate renal mfAMLs from other renal tumors. -- Abstract: Objectives: The purpose of this retrospective study was to evaluate the diagnostic performance of double-echo gradient chemical shift (GRE) magnetic resonance (MR) imaging for the differentiation of angiomyolipomas with minimal fat (mfAML) from other homogeneous solid renal tumors. Methods: Between 2005 and 2010 in two institutions, all histologically proven homogenous solid renal tumors imaged with computed tomography and MR imaging, including GRE sequences, have been retrospectively selected. A total of 118 patients (mean age: 61 years; range: 20–87) with 119 tumors were included. Two readers measured independently the signal intensity (SI) on GRE images and calculated SI index (SII) and tumor-to-spleen ratio (TSR) on in-phase and opposed-phase images. Intra- and interreader agreement was obtained. Cut-off values were derived from the receiver operating characteristic (ROC) curve analysis. Results: Twelve mfAMLs in 11 patients were identified (mean size: 2.8 cm; range: 1.2–3.5), and 107 non-AML tumors (3.2 cm; 1–7.8) in 107 patients. The intraobserver reproducibility of SII and TSR was excellent with an intraclass correlation coefficient equal to 0.99 [0.98–0.99]. The coefficient of correlation between the readers was 0.99. The mean values of TSR for mfAMLs and non-mfAMLs were −7.0 ± 22.8 versus −8.2 ± 21.2 for reader 1 and −6.7 ± 22.8 versus −8.4 ± 20.9 for reader 2 respectively. No significant difference was noticed between the two groups for SII (p = 0.98) and TSR (p = 0.86). Only 1 out of 12 mfAMLs and 11 of 107 non-AML tumors presented with a TSR inferior to −30% (p = 0.83). Conclusion: In a routine practice, GRE sequences cannot be a confident tool to

  15. Identification of Zinc-ligated Cysteine Residues Based on {sup 13}C{alpha} and {sup 13}C{beta} Chemical Shift Data

    Energy Technology Data Exchange (ETDEWEB)

    Kornhaber, Gregory J.; Snyder, David; Moseley, Hunter N. B.; Montelione, Gaetano T. [Rutgers University, Center for Advanced Biotechnology and Medicine, Department of Molecular Biology and Biochemistry (United States)], E-mail: guy@cabm.rutgers.edu

    2006-04-15

    Although a significant number of proteins include bound metals as part of their structure, the identification of amino acid residues coordinated to non-paramagnetic metals by NMR remains a challenge. Metal ligands can stabilize the native structure and/or play critical catalytic roles in the underlying biochemistry. An atom's chemical shift is exquisitely sensitive to its electronic environment. Chemical shift data can provide valuable insights into structural features, including metal ligation. In this study, we demonstrate that overlapped {sup 13}C{beta} chemical shift distributions of Zn-ligated and non-metal-ligated cysteine residues are largely resolved by the inclusion of the corresponding {sup 13}C{alpha} chemical shift information, together with secondary structural information. We demonstrate this with a bivariate distribution plot, and statistically with a multivariate analysis of variance (MANOVA) and hierarchical logistic regression analysis. Using 287 {sup 13}C{alpha}/{sup 13}C{beta} shift pairs from 79 proteins with known three-dimensional structures, including 86 {sup 13}C{alpha} and{sup 13}C{beta} shifts for 43 Zn-ligated cysteine residues, along with corresponding oxidation state and secondary structure information, we have built a logistic regression model that distinguishes between oxidized cystines, reduced (non-metal ligated) cysteines, and Zn-ligated cysteines. Classifying cysteines/cystines with a statisical model incorporating all three phenomena resulted in a predictor of Zn ligation with a recall, precision and F-measure of 83.7%, and an accuracy of 95.1%. This model was applied in the analysis of Bacillus subtilis IscU, a protein involved in iron-sulfur cluster assembly. The model predicts that all three cysteines of IscU are metal ligands. We confirmed these results by (i) examining the effect of metal chelation on the NMR spectrum of IscU, and (ii) inductively coupled plasma mass spectrometry analysis. To gain further insight into

  16. Sugarcane productivity correlated with physical-chemical attributes to create soil management zone

    Directory of Open Access Journals (Sweden)

    Flávio Carlos Dalchiavon

    2013-10-01

    Full Text Available The socioeconomic importance of sugar cane in Brazil is unquestionable because it is the raw material for the production of ethanol and sugar. The accurate spatial intervention in the management of the crop, resulting zones of soil management, increases productivity as well as its agricultural yields. The spatial and Person's correlations between sugarcane attributes and physico-chemical attributes of a Typic Tropustalf were studied in the growing season of 2009, in Suzanápolis, State of São Paulo, Brazil (20°28'10'' S lat.; 50°49'20'' W long., in order to obtain the one that best correlates with agricultural productivity. Thus, the geostatistical grid with 120 sampling points was installed to soil and data collection in a plot of 14.6 ha with second crop sugarcane. Due to their substantial and excellent linear and spatial correlations with the productivity of the sugarcane, the population of plants and the organic matter content of the soil, by evidencing substantial correlations, linear and spatial, with the productivity of sugarcane, were indicators of management zones strongly attached to such productivity.

  17. The cerebral correlates of set-shifting: an fMRI study of the trail making test

    Directory of Open Access Journals (Sweden)

    Moll Jorge

    2002-01-01

    Full Text Available The trail making test (TMT pertains to a family of tests that tap the ability to alternate between cognitive categories. However, the value of the TMT as a localizing instrument remains elusive. Here we report the results of a functional magnetic resonance imaging (fMRI study of a verbal adaptation of the TMT (vTMT. The vTMT takes advantage of the set-shifting properties of the TMT and, at the same time, minimizes the visuospatial and visuomotor components of the written TMT. Whole brain BOLD fMRI was performed during the alternating execution of vTMTA and vTMTB in seven normal adults with more than 12 years of formal education. Brain activation related to the set-shifting component of vTMTB was investigated by comparing performance on vTMTB with vTMTA, a simple counting task. There was a marked asymmetry of activation in favor of the left hemisphere, most notably in dorsolateral prefrontal cortex (BA 6 lateral, 44 and 46 and supplementary motor area/cingulate sulcus (BA 6 medial and 32. The intraparietal sulcus (BA 7 and 39 was bilaterally activated. These findings are in line with clinico-anatomic and functional neuroimaging data that point to a critical role of the dorsolateral and medial prefrontal cortices as well as the intraparietal sulci in the regulation of cognitive flexibility, intention, and the covert execution of saccades/anti-saccades. Many commonly used neuropsychological paradigms, such as the Stroop, Wisconsin Card Sorting, and go - no go tasks, share some patterns of cerebral activation with the TMT.

  18. Study of rosin-glycerol esters as microencapsulating materials. II. Quantitative correlation between physico-chemical properties and release characteristics.

    Science.gov (United States)

    Pathak, Y V; Rao, M N; Dorle, A K

    1985-01-01

    Rosin-glycerol esters have been used as microencapsulating materials. A quantitative correlation has been observed between the physico-chemical properties, i.e. acid value and moisture affinity, and the release characteristics from the encapsulated drug.

  19. In Situ Solid-State Reactions Monitored by X-ray Absorption Spectroscopy: Temperature-Induced Proton Transfer Leads to Chemical Shifts.

    Science.gov (United States)

    Stevens, Joanna S; Walczak, Monika; Jaye, Cherno; Fischer, Daniel A

    2016-10-24

    The dramatic colour and phase alteration with the solid-state, temperature-dependent reaction between squaric acid and 4,4'-bipyridine has been probed in situ with X-ray absorption spectroscopy. The electronic and chemical sensitivity to the local atomic environment through chemical shifts in the near-edge X-ray absorption fine structure (NEXAFS) revealed proton transfer from the acid to the bipyridine base through the change in nitrogen protonation state in the high-temperature form. Direct detection of proton transfer coupled with structural analysis elucidates the nature of the solid-state process, with intermolecular proton transfer occurring along an acid-base chain followed by a domino effect to the subsequent acid-base chains, leading to the rapid migration along the length of the crystal. NEXAFS thereby conveys the ability to monitor the nature of solid-state chemical reactions in situ, without the need for a priori information or long-range order.

  20. Correlative atomic force and confocal fluorescence microscopy: single molecule imaging and force induced spectral shifts (Conference Presentation)

    Science.gov (United States)

    Basché, Thomas; Hinze, Gerald; Stöttinger, Sven

    2016-09-01

    A grand challenge in nanoscience is to correlate structure or morphology of individual nano-sized objects with their photo-physical properties. An early example have been measurements of the emission spectra and polarization of single semiconductor quantum dots as well as their crystallographic structure by a combination of confocal fluorescence microscopy and transmission electron microscopy.[1] Recently, the simultaneous use of confocal fluorescence and atomic force microscopy (AFM) has allowed for correlating the morphology/conformation of individual nanoparticle oligomers or molecules with their photo-physics.[2, 3] In particular, we have employed the tip of an AFM cantilever to apply compressive stress to single molecules adsorbed on a surface and follow the effect of the impact on the electronic states of the molecule by fluorescence spectroscopy.[3] Quantum mechanical calculations corroborate that the spectral changes induced by the localized force can be associated to transitions among the different possible conformers of the adsorbed molecule.

  1. 4D Non-uniformly sampled HCBCACON and {sup 1}J(NC{sup {alpha}})-selective HCBCANCO experiments for the sequential assignment and chemical shift analysis of intrinsically disordered proteins

    Energy Technology Data Exchange (ETDEWEB)

    Novacek, Jiri [Masaryk University, Faculty of Science, NCBR, and CEITEC (Czech Republic); Haba, Noam Y.; Chill, Jordan H. [Bar Ilan University, Department of Chemistry (Israel); Zidek, Lukas, E-mail: lzidek@chemi.muni.cz; Sklenar, Vladimir [Masaryk University, Faculty of Science, NCBR, and CEITEC (Czech Republic)

    2012-06-15

    A pair of 4D NMR experiments for the backbone assignment of disordered proteins is presented. The experiments exploit {sup 13}C direct detection and non-uniform sampling of the indirectly detected dimensions, and provide correlations of the aliphatic proton (H{sup {alpha}}, and H{sup {beta}}) and carbon (C{sup {alpha}}, C{sup {beta}}) resonance frequencies to the protein backbone. Thus, all the chemical shifts regularly used to map the transient secondary structure motifs in the intrinsically disordered proteins (H{sup {alpha}}, C{sup {alpha}}, C{sup {beta}}, C Prime , and N) can be extracted from each spectrum. Compared to the commonly used assignment strategy based on matching the C{sup {alpha}} and C{sup {beta}} chemical shifts, inclusion of the H{sup {alpha}} and H{sup {beta}} provides up to three extra resonance frequencies that decrease the chance of ambiguous assignment. The experiments were successfully applied to the original assignment of a 12.8 kDa intrinsically disordered protein having a high content of proline residues (26 %) in the sequence.

  2. Correlation of Chemical and Physical Test Data For the Environment Ageing of Coflon (PVDF). Revised

    Science.gov (United States)

    Morgan, G. J.; Campion, R. P.

    1997-01-01

    This report aims to identify correlations between mechanical property changes and chemical/morphological structure changes for Coflon. It is intended both to illustrate the overall methodology and to indicate the testing that needs to be undertaken in order to obtain correlations. Many fluid exposures have now been carried out on Coflon during the project and many data generated as a result. The report summarises the changes observed in mechanical and physical properties and relates these as well as possible to the chemistry thought to be occurring during ageing. For this purpose, data have been collated from already-issued MERL and TRI technical and progress reports. Most of the mechanical testing of aged testpieces has been performed soon after the completion of the exposure; however, there is of necessity a delay in obtaining chemical analysis of the same testpieces, so that more physical than chemical data are shown. Three fluids have so far caused measurable deterioration of Coflon, these being: methanol (Fluid A), a methanol and amine mixture (Fluid G), and a mixture of methane, carbon dioxide gas and hydrogen sulphide gas plus aqueous amine (Fluid F). Only the effects of these fluids will be dealt with in any detail in this report, although other fluids are assessed to give relevant background information. Relevant test data collated here include: tensile modulus and related properties, mode of sample failure at break, fracture toughness, fatigue crack growth rate and resistance, stress relaxation rate, permeation coefficients, % crystallinity and molecular weight distributions together with changes in fluorine levels, and other observations where appropriate. However, not all of these were obtained for every ageing condition. Because of the wide range of tests employed, and the different ways in which their results are obtained, the following section has been included to serve as a background for making comparisons.

  3. THE APPLICATION OF AUTOMATED CORRELATION OPTIMIZED WARPING TO THE QUALITY EVALUATION OF Radix Puerariae thomsonii: CORRECTING RETENTION TIME SHIFT IN THE CHROMATOGRAPHIC FINGERPRINTS

    Directory of Open Access Journals (Sweden)

    Long Jiao

    2015-01-01

    Full Text Available The application of automated correlation optimized warping (ACOW to the correction of retention time shift in the chromatographic fingerprints of Radix Puerariae thomsonii (RPT was investigated. Twenty-seven samples were extracted from 9 batches of RPT products. The fingerprints of the 27 samples were established by the HPLC method. Because there is a retention time shift in the established fingerprints, the quality of these samples cannot be correctly evaluated by using similarity estimation and principal component analysis (PCA. Thus, the ACOW method was used to align these fingerprints. In the ACOW procedure, the warping parameters, which have a significant influence on the alignment result, were optimized by an automated algorithm. After correcting the retention time shift, the quality of these RPT samples was correctly evaluated by similarity estimation and PCA. It is demonstrated that ACOW is a practical method for aligning the chromatographic fingerprints of RPT. The combination of ACOW, similarity estimation, and PCA is shown to be a promising method for evaluating the quality of Traditional Chinese Medicine.

  4. Lead-lag cross-sectional structure and detection of correlated-anticorrelated regime shifts: Application to the volatilities of inflation and economic growth rates

    CERN Document Server

    Zhou, W X; Sornette, Didier; Zhou, Wei-Xing

    2006-01-01

    We have recently introduced the ``thermal optimal path'' (TOP) method to investigate the real-time lead-lag structure between two time series. The TOP method consists in searching for a robust noise-averaged optimal path of the distance matrix along which the two time series have the greatest similarity. Here, we generalize the TOP method by introducing a more general definition of distance which takes into account possible regime shifts between positive and negative correlations. This generalization to track possible changes of correlation signs is able to identify possible transitions from one convention (or consensus) to another. Numerical simulations on synthetic time series verify that the new TOP method performs as expected even in the presence of substantial noise. We then apply it to investigate changes of convention in the dependence structure between the historical volatilities of the USA inflation rate and economic growth rate. Several measures show that the new TOP method significantly outperforms...

  5. A Cross-Correlated Trellis-Coded Quadrature Modulation Representation of MIL-STD Shaped Offset Quadrature Phase-Shift Keying

    Science.gov (United States)

    Simon, M. K.; Li, L.

    2003-08-01

    We show that MIL-STD shaped offset quadrature phase-shift keying (SOQPSK), a highly bandwidth-efficient constant-envelope modulation, can be represented in the form of a cross-correlated trellis-coded quadrature modulation, a generic structure containing both memory and cross-correlation between the in-phase and quadrature-phase channels. Such a representation allows identification of the optimum form of receiver for MIL-STD SOQPSK and at the same time, through modification of the equivalent I and Q encoders to recursive types, allows for it to be embedded as the inner code of a serial or parallel (turbo-like) concatenated coding structure together with iterative decoding.

  6. Effects of irritant chemicals on Aedes aegypti resting behavior: is there a simple shift to untreated "safe sites"?

    Directory of Open Access Journals (Sweden)

    Hortance Manda

    2011-07-01

    Full Text Available BACKGROUND: Previous studies have identified the behavioral responses of Aedes aegypti to irritant and repellent chemicals that can be exploited to reduce man-vector contact. Maximum efficacy of interventions based on irritant chemical actions will, however, require full knowledge of variables that influence vector resting behavior and how untreated "safe sites" contribute to overall impact. METHODS: Using a laboratory box assay, resting patterns of two population strains of female Ae. aegypti (THAI and PERU were evaluated against two material types (cotton and polyester at various dark:light surface area coverage (SAC ratio and contrast configuration (horizontal and vertical under chemical-free and treated conditions. Chemicals evaluated were alphacypermethrin and DDT at varying concentrations. RESULTS: Under chemical-free conditions, dark material had significantly higher resting counts compared to light material at all SAC, and significantly increased when material was in horizontal configuration. Cotton elicited stronger response than polyester. Within the treatment assays, significantly higher resting counts were observed on chemical-treated dark material compared to untreated light fabric. However, compared to matched controls, significantly less resting observations were made on chemical-treated dark material overall. Most importantly, resting observations on untreated light material (or "safe sites" in the treatment assay did not significantly increase for many of the tests, even at 25% SAC. Knockdown rates were ≤5% for all assays. Significantly more observations of flying mosquitoes were made in test assays under chemical-treatment conditions as compared to controls. CONCLUSIONS/SIGNIFICANCE: When preferred Ae. aegypti resting sites are treated with chemicals, even at reduced treatment coverage area, mosquitoes do not simply move to safe sites (untreated areas following contact with the treated material. Instead, they become agitated

  7. Transport-induced shifts in condensate dew-point and composition in multicomponent systems with chemical reaction

    Science.gov (United States)

    Rosner, D. E.; Nagarajan, R.

    1985-01-01

    Partial heterogeneous condensation phenomena in multicomponent reacting systems are analyzed taking into consideration the chemical element transport phenomena. It is demonstrated that the dew-point surface temperature in chemically reactive systems is not a purely thermodynamic quantity, but is influenced by the multicomponent diffusion and Soret-mass diffusion phenomena. Several distinct dew-points are shown to exist in such systems and, as a result of transport constraints, the 'sharp' locus between two chemically distinct condensates is systematically moved to a difference mainstream composition.

  8. Phonon frequency shift and effect of correlation on the electron-phonon interaction in heavy fermion systems

    Indian Academy of Sciences (India)

    B Ojha; P Nayak; S N Behera

    2000-02-01

    The electron–phonon interaction in the periodic Anderson model (PAM) is considered. The PAM incorporates the effect of onsite Coulomb interaction () between -electrons. The influence of Coulomb correlation on the phonon response of the system is studied by evaluating the phonon spectral function for various parameters of the model. The numerical evaluation of the spectral function is carried out in the long wavelength limit at finite temperatures keeping only linear terms in . The observed behaviour is found to agree well with the general features obtained experimentally for some heavy fermion (HF) systems.

  9. Adaptive evolution of the symbiotic gene NORK is not correlated with shifts of rhizobial specificity in the genus Medicago

    Directory of Open Access Journals (Sweden)

    Ronfort Joëlle

    2007-11-01

    Full Text Available Abstract Background The NODULATION RECEPTOR KINASE (NORK gene encodes a Leucine-Rich Repeat (LRR-containing receptor-like protein and controls the infection by symbiotic rhizobia and endomycorrhizal fungi in Legumes. The occurrence of numerous amino acid changes driven by directional selection has been reported in this gene, using a limited number of messenger RNA sequences, but the functional reason of these changes remains obscure. The Medicago genus, where changes in rhizobial associations have been previously examined, is a good model to test whether the evolution of NORK is influenced by rhizobial interactions. Results We sequenced a region of 3610 nucleotides (encoding a 392 amino acid-long region of the NORK protein in 32 Medicago species. We confirm that positive selection in NORK has occurred within the Medicago genus and find that the amino acid positions targeted by selection occur in sites outside of solvent-exposed regions in LRRs, and other sites in the N-terminal region of the protein. We tested if branches of the Medicago phylogeny where changes of rhizobial symbionts occurred displayed accelerated rates of amino acid substitutions. Only one branch out of five tested, leading to M. noeana, displays such a pattern. Among other branches, the most likely for having undergone positive selection is not associated with documented shift of rhizobial specificity. Conclusion Adaptive changes in the sequence of the NORK receptor have involved the LRRs, but targeted different sites than in most previous studies of LRR proteins evolution. The fact that positive selection in NORK tends not to be associated to changes in rhizobial specificity indicates that this gene was probably not involved in evolving rhizobial preferences. Other explanations (e.g. coevolutionary arms race must be tested to explain the adaptive evolution of NORK.

  10. Compressive Shift Retrieval

    Science.gov (United States)

    Ohlsson, Henrik; Eldar, Yonina C.; Yang, Allen Y.; Sastry, S. Shankar

    2014-08-01

    The classical shift retrieval problem considers two signals in vector form that are related by a shift. The problem is of great importance in many applications and is typically solved by maximizing the cross-correlation between the two signals. Inspired by compressive sensing, in this paper, we seek to estimate the shift directly from compressed signals. We show that under certain conditions, the shift can be recovered using fewer samples and less computation compared to the classical setup. Of particular interest is shift estimation from Fourier coefficients. We show that under rather mild conditions only one Fourier coefficient suffices to recover the true shift.

  11. On the detectability of trace chemical species in the martian atmosphere using gas correlation filter radiometry

    Science.gov (United States)

    Sinclair, J. A.; Irwin, P. G. J.; Calcutt, S. B.; Wilson, E. L.

    2015-11-01

    The martian atmosphere is host to many trace gases including water (H2O) and its isotopologues, methane (CH4) and potentially sulphur dioxide (SO2), nitrous oxide (N2O) and further organic compounds, which would serve as indirect tracers of geological, chemical and biological processes on Mars. With exception of the recent detection of CH4 by Curiosity, previous detections of these species have been unsuccessful or considered tentative due to the low concentrations of these species in the atmosphere (∼10-9 partial pressures), limited spectral resolving power and/or signal-to-noise and the challenge of discriminating between telluric and martian features when observing from the Earth. In this study, we present radiative transfer simulations of an alternative method for detection of trace gas species - the gas correlation radiometry method. Two potential observing scenarios were explored where a gas correlation filter radiometer (GCFR) instrument: (1) performs nadir and/or limb sounding of the martian atmosphere in the thermal infrared (200-2000 cm-1 from an orbiting spacecraft or (2) performs solar occultation measurements in the near-infrared (2000-5000 cm-1) from a lander on the martian surface. In both scenarios, simulations of a narrowband filter radiometer (without gas correlation) were also generated to serve as a comparison. From a spacecraft, we find that a gas correlation filter radiometer, in comparison to a filter radiometer (FR), offers a greater discrimination between temperature and dust, a greater discrimination between H2O and HDO, and would allow detection of N2O and CH3OH at concentrations of ∼10 ppbv and ∼2 ppbv, respectively, which are lower than previously-derived upper limits. However, the lowest retrievable concentration of SO2 (approximately 2 ppbv) is comparable with previous upper limits and CH4 is only detectable at concentrations of approximately 10 ppbv, which is an order of magnitude higher than the concentration recently measured

  12. Diffusion tensor imaging and chemical shift imaging assessment of heterogeneity in low grade glioma under temozolomide chemotherapy.

    Science.gov (United States)

    Sijens, P E; Heesters, M A A M; Enting, R H; van der Graaf, W T A; Potze, J H; Irwan, R; Meiners, L C; Oudkerk, M

    2007-12-01

    Diffusion tensor imaging and multiple voxel magnetic resonance spectroscopy were performed in the MRI follow-up of a patient with a glioma treated with temozolomide chemotherapy. Tumor shrinkage was paralleled by reductions in choline level and by increases in apparent diffusion coefficient indicating decreased cellularity. Within the tumor, choline level and apparent diffusion coefficient showed a significant inverse correlation (P < 0.01). Fractional anisotropy distribution in the tumor correlated positively with N-acetyl aspartate level (P < 0.001), indicating that these parameters reflect (remaining) axonal structure. Tumor lactate level, also found to decrease under therapy, did not correlate with any other parameter.

  13. 平衡电负性与烷烃核磁共振碳谱位移%EQUILIBRIUM ELECTRONEGATIVITY AND 13C NMR CHEMICAL SHIFTS OF ALKANES

    Institute of Scientific and Technical Information of China (English)

    聂长明; 文松年

    2001-01-01

    In this paper, the atomic equilibrium electronegativity in a molecule has been defined and the model of 13C NMR chemical shifts of alkanes has been studied with the atomic equilibrium electronegativity and the structural information parameters NiH(i=0,α,β,γ) and NjC(j=α,β,γ). The results indicate that the 13C NMR chemical shifts of alkanes can be described as follows: CS=-1736.776+755.118AEE+5.2539N0H+1.8837NβH-0.2066NγH By the use of the formula the chemical shifts of 99 carbon atoms are predicated, and the standard error is only 0.9861ppm. The average absolute error is 0.78ppm, The calculated values conform very much to the observed values.%定义了烷烃分子中碳原子的平衡电负性(AEE),用平衡电负性和NiH(i=0,α,β,γ)和NjC(j=α,β,γ)结构信息参数研究了烷烃的13C NMR化学位移模型.结果表明,烷烃13C NMR化学位移(CS)可用下式来定量描述: CS=-1736.776+755.118AEE+5.2539N0H+1.8837NβH-0.2066NγH   用上式估算了99个碳原子的化学位移,标准差为0.9861ppm,平均绝对误差0.78ppm,预测值与实验值十分吻合.

  14. Prediction of microvascular invasion of hepatocellular carcinomas with gadoxetic acid-enhanced MR imaging: Impact of intra-tumoral fat detected on chemical-shift images

    Energy Technology Data Exchange (ETDEWEB)

    Min, Ji Hye [Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); Kim, Young Kon, E-mail: jmyr@dreamwiz.com [Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); Lim, Sanghyeok [Department of Radiology, Guri Hospital, Hanyang University College of Medicine, Guri (Korea, Republic of); Jeong, Woo Kyoung; Choi, Dongil; Lee, Won Jae [Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of)

    2015-06-15

    Highlights: • Intra-tumoral fat detected with MR imaging may suggest lower risk for MVI of HCC. • Alfa-fetoprotein, tumor size, and fat component were associated with MVI of HCC. • Chemical shift MRI should be considered for the evaluation of HCC. - Abstract: Purpose: To investigate the impact of intra-tumoral fat detected by chemical-shift MR imaging in predicting the MVI of HCC. Materials and methods: Gadoxetic acid-enhanced MR imaging of 365 surgically proven HCCs from 365 patients (306 men, 59 women; mean age, 55.6 years) were evaluated. HCCs were classified into two groups, fat-containing and non-fat-containing, based on the presence of fat on chemical-shift images. Fat-containing HCCs were subdivided into diffuse or focal fatty change groups. Logistic regression analyses were used to identify clinical and MR findings associated with MVI. Results: Based on MR imaging, 66 tumors were classified as fat-containing HCCs and 299 as non-fat-containing HCCs. Among the 66 fat-containing HCCs, 38 (57.6%) showed diffuse fatty changes and 28 (42.4%) showed focal fatty changes. MVI was present in 18 (27.3%) fat-containing HCCs and in 117 (39.1%) non-fat-containing HCCs (P = 0.07). Univariate analysis revealed that serum alpha-fetoprotein (AFP) and tumor size were significantly associated with MVI (P < 0.001). A multiple logistic regression analysis showed that log AFP (odds ratio 1.178, P = 0.0016), tumor size (odds ratio 1.809, P < 0.001), and intra-tumoral fat (odds ratio 0.515, P = 0.0387) were independent variables associated with MVI. Conclusion: Intra-tumoral fat detected with MR imaging may suggest lower risk for MVI of HCC and, therefore, a possibly more favorable prognosis, but the clinical value of this finding is uncertain.

  15. Chemical shift magnetic resonance imaging in differentiation of benign from malignant vertebral collapse in a rural tertiary care hospital in North India

    Science.gov (United States)

    Mittal, Puneet; Gupta, Ranjana; Mittal, Amit; Joshi, Sandeep

    2016-01-01

    Introduction: Magnetic resonance imaging (MRI) is the modality of the first choice for evaluation of vertebral compression/collapse. Many MRI qualitative features help to differentiate benign from malignant collapse. We conducted this study to look for a quantitative difference in chemical shift values in benign and malignant collapse using dual-echo gradient echo in-phase/out-phase imaging. Materials and Methods: MRI examinations of a total of 38 patients were retrospectively included in the study who had vertebral compression/collapse with marrow edema in which final diagnosis was available at the time of imaging/follow-up. Signal intensity value in the region of abnormal marrow signal and adjacent normal vertebra was measured on in phase/out phase images. Signal intensity ratio (SIR) was measured by dividing signal intensity value on opposite phase images to that on in phase images. SIR was compared in normal vertebrae and benign and malignant vertebral collapse. Results: There were 21 males and 17 females with mean age of 52.4 years (range 28–76 years). Out of total 38 patients, 18 were of benign vertebral collapse and 20 of malignant vertebral collapse. SIR in normal vertebrae was 0.30 ± 0.14, 0.67 ± 0.18 in benign vertebral collapse, and 1.20 ± 0.27 in malignant vertebral collapse with significant difference in SIR of normal vertebrae versus benign collapse (P < 0.01) and in benign collapse versus malignant collapse (P < 0.01). Assuming a cutoff of <0.95 for benign collapse and ≥0.95 for malignant collapse, chemical shift imaging had a sensitivity of 90% and specificity of 94.4%. Conclusion: Chemical shift imaging is a rapid and useful sequence in differentiating benign from malignant vertebral collapse with good specificity and sensitivity.

  16. 1H NMR spectra. Part 30(+): 1H chemical shifts in amides and the magnetic anisotropy, electric field and steric effects of the amide group.

    Science.gov (United States)

    Abraham, Raymond J; Griffiths, Lee; Perez, Manuel

    2013-03-01

    The (1)H spectra of 37 amides in CDCl(3) solvent were analysed and the chemical shifts obtained. The molecular geometries and conformational analysis of these amides were considered in detail. The NMR spectral assignments are of interest, e.g. the assignments of the formamide NH(2) protons reverse in going from CDCl(3) to more polar solvents. The substituent chemical shifts of the amide group in both aliphatic and aromatic amides were analysed using an approach based on neural network data for near (≤3 bonds removed) protons and the electric field, magnetic anisotropy, steric and for aromatic systems π effects of the amide group for more distant protons. The electric field is calculated from the partial atomic charges on the N.C═O atoms of the amide group. The magnetic anisotropy of the carbonyl group was reproduced with the asymmetric magnetic anisotropy acting at the midpoint of the carbonyl bond. The values of the anisotropies Δχ(parl) and Δχ(perp) were for the aliphatic amides 10.53 and -23.67 (×10(-6) Å(3)/molecule) and for the aromatic amides 2.12 and -10.43 (×10(-6) Å(3)/molecule). The nitrogen anisotropy was 7.62 (×10(-6) Å(3)/molecule). These values are compared with previous literature values. The (1)H chemical shifts were calculated from the semi-empirical approach and also by gauge-independent atomic orbital calculations with the density functional theory method and B3LYP/6-31G(++) (d,p) basis set. The semi-empirical approach gave good agreement with root mean square error of 0.081 ppm for the data set of 280 entries. The gauge-independent atomic orbital approach was generally acceptable, but significant errors (ca. 1 ppm) were found for the NH and CHO protons and also for some other protons.

  17. Halogen effect on structure and 13C NMR chemical shift of 3,6-disubstituted-N-alkyl carbazoles

    DEFF Research Database (Denmark)

    Radula-Janik, Klaudia; Kupka, Teobald; Ejsmont, Krzysztof

    2013-01-01

    Structures of selected 3,6-dihalogeno-N-alkyl carbazole derivatives were calculated at the B3LYP/6-311++G(3df,2pd) level of theory and their 13C NMR isotropic nuclear shieldings were predicted using density functional theory (DFT). The model compounds contained 9H-, N-methyl and N-ethyl derivatives......). The decreasing electronegativity of the halogen substituent (F, Cl, Br and I) was reflected in both nonrelativistic and relativistic NMR results as decreased values of chemical shifts of carbon atoms attached to halogen (C3 and C6) leading to a strong sensitivity to halogen atom type at 3 and 6 positions...

  18. Other compounds isolated from Simira glaziovii and the {sup 1}H and {sup 13}C NMR chemical shift assignments of new 1-epi-castanopsol

    Energy Technology Data Exchange (ETDEWEB)

    Araujo, Marcelo F. de; Vieira, Ivo J. Curcino [Universidade Federal Rural do Rio de Janeiro, Seropedica, RJ (Brazil). Dept. de Quimica; Braz-Filho, Raimundo [Universidade Estadual do Norte Fluminense (UENF), Campos dos Goytacases, RJ (Brazil). Centro de Ciencias Tecnologicas. Lab. de Ciencias Quimicas; Carvalho, Mario G. de, E-mail: mgeraldo@ufrrj.br [Universidade Federal do Rio de Janeiro (NPPN/UFRJ), RJ (Brazil). Centro de Ciencias da Saude. Nucleo de Pesquisa em Produtos Naturais

    2012-07-01

    A new triterpene, 1-epi-castanopsol, besides eleven known compounds: sitosterol, stigmasterol, campesterol, lupeol, lupenone, simirane B, syringaresinol, scopoletin, isofraxidin, 6,7,8-trimethoxycoumarin and harman, were isolated from the wood of Simira glaziovii. The structures of the known compounds were defined by 1D, 2D {sup 1}H, {sup 13}C NMR spectra data analyses and comparison with literature data. The detailed spectral data analyses allowed the definition of the structure of the new 1-epi isomer of castanopsol and performance of {sup 1}H and {sup 13}C NMR chemical shift assignments. (author)

  19. Accurate calculation of chemical shifts in highly dynamic H2@C60 through an integrated quantum mechanics/molecular dynamics scheme.

    Science.gov (United States)

    Jiménez-Osés, Gonzalo; García, José I; Corzana, Francisco; Elguero, José

    2011-05-20

    A new protocol combining classical MD simulations and DFT calculations is presented to accurately estimate the (1)H NMR chemical shifts of highly mobile guest-host systems and their thermal dependence. This strategy has been successfully applied for the hydrogen molecule trapped into C(60) fullerene, an unresolved and challenging prototypical case for which experimental values have never been reproduced. The dependence of the final values on the theoretical method and their implications to avoid over interpretation of the obtained results are carefully described.

  20. 1H, 13C and 15N backbone and side-chain chemical shift assignment of the Fyn SH2 domain and its complex with a phosphotyrosine peptide.

    Science.gov (United States)

    Huculeci, Radu; Buts, Lieven; Lenaerts, Tom; van Nuland, Nico A J

    2011-10-01

    SH2 domains are interaction modules uniquely dedicated to recognize phosphotyrosine sites, playing a central role in for instance the activation of tyrosine kinases or phosphatases. Here we report the (1)H, (15)N and (13)C backbone and side-chain chemical shift assignments of the SH2 domain of the human protein tyrosine kinase Fyn, both in its free state and bound to a high-affinity phosphotyrosine peptide corresponding to a specific sequence in the hamster middle-T antigen. The BMRB accession numbers are 17,368 and 17,369, respectively.

  1. Spatio-temporal variability of airborne bacterial communities and their correlation with particulate matter chemical composition across two urban areas.

    Science.gov (United States)

    Gandolfi, I; Bertolini, V; Bestetti, G; Ambrosini, R; Innocente, E; Rampazzo, G; Papacchini, M; Franzetti, A

    2015-06-01

    The study of spatio-temporal variability of airborne bacterial communities has recently gained importance due to the evidence that airborne bacteria are involved in atmospheric processes and can affect human health. In this work, we described the structure of airborne microbial communities in two urban areas (Milan and Venice, Northern Italy) through the sequencing, by the Illumina platform, of libraries containing the V5-V6 hypervariable regions of the 16S rRNA gene and estimated the abundance of airborne bacteria with quantitative PCR (qPCR). Airborne microbial communities were dominated by few taxa, particularly Burkholderiales and Actinomycetales, more abundant in colder seasons, and Chloroplasts, more abundant in warmer seasons. By partitioning the variation in bacterial community structure, we could assess that environmental and meteorological conditions, including variability between cities and seasons, were the major determinants of the observed variation in bacterial community structure, while chemical composition of atmospheric particulate matter (PM) had a minor contribution. Particularly, Ba, SO4 (2-) and Mg(2+) concentrations were significantly correlated with microbial community structure, but it was not possible to assess whether they simply co-varied with seasonal shifts of bacterial inputs to the atmosphere, or their variation favoured specific taxa. Both local sources of bacteria and atmospheric dispersal were involved in the assembling of airborne microbial communities, as suggested, to the one side by the large abundance of bacteria typical of lagoon environments (Rhodobacterales) observed in spring air samples from Venice and to the other by the significant effect of wind speed in shaping airborne bacterial communities at all sites.

  2. Chemical evolution, petrogenesis, and regional chemical correlations of the flood basalt sequence in the central Deccan Traps, India

    Indian Academy of Sciences (India)

    Leone Melluso; Mario Barbieri; Luigi Beccaluva

    2004-12-01

    The lava sequence of the central-western Deccan Traps (from Jalgaon towards Mumbai) is formed by basalts and basaltic andesites having a significant variation in TiO2 (from 1.2 to 3.3 wt%), Zr (from 84 to 253 ppm), Nb (from 5 to 16 ppm) and Ba (from 63 to 407 ppm), at MgO ranging from 10 to 4.2 wt%. Most of these basalts follow a liquid line of descent dominated by low pressure fractionation of clinopyroxene, plagioclase and olivine, starting from the most mafic compositions, in a temperature range from 1220° to 1125°C. These rocks resemble those belonging to the lowermost formations of the Deccan Traps in the Western Ghats (Jawhar, Igatpuri and Thakurvadi) as well as those of the Poladpur formation. Samples analyzed for 87Sr/86Sr give a range of initial ratios from 0.70558 to 0.70621. A group of flows of the Dhule area has low TiO2 (1.2–1.5 wt%) and Zr (84–105 ppm) at moderate MgO (5.2–6.2 wt%), matching the composition of low-Ti basalts of Gujarat, low-Ti dykes of the Tapti swarm and Toranmal basalts, just north of the study area. This allows chemical correlations between the lavas of central Deccan, the Tapti dykes and the northwestern outcrops. The mildly enriched high field strength element contents of the samples with TiO2 < 1.5 wt% make them products of mantle sources broadly similar to those which generated the Ambenali basalts, but their high La/Nb and Ba/Nb, negative Nb anomalies in the mantle normalized diagrams, and relatively high 87Sr/86Sr, make evident a crustal input with crustally derived materials at less differentiated stages than those represented in this sample set, or even within the sub-Indian lithospheric mantle.

  3. Fractional enrichment of proteins using [2-{sup 13}C]-glycerol as the carbon source facilitates measurement of excited state {sup 13}Cα chemical shifts with improved sensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Ahlner, Alexandra; Andresen, Cecilia; Khan, Shahid N. [Linköping University, Division of Chemistry, Department of Physics, Chemistry and Biology (Sweden); Kay, Lewis E. [The University of Toronto, Departments of Molecular Genetics, Biochemistry and Chemistry, One King’s College Circle (Canada); Lundström, Patrik, E-mail: patlu@ifm.liu.se [Linköping University, Division of Chemistry, Department of Physics, Chemistry and Biology (Sweden)

    2015-07-15

    A selective isotope labeling scheme based on the utilization of [2-{sup 13}C]-glycerol as the carbon source during protein overexpression has been evaluated for the measurement of excited state {sup 13}Cα chemical shifts using Carr–Purcell–Meiboom–Gill (CPMG) relaxation dispersion (RD) experiments. As expected, the fractional incorporation of label at the Cα positions is increased two-fold relative to labeling schemes based on [2-{sup 13}C]-glucose, effectively doubling the sensitivity of NMR experiments. Applications to a binding reaction involving an SH3 domain from the protein Abp1p and a peptide from the protein Ark1p establish that accurate excited state {sup 13}Cα chemical shifts can be obtained from RD experiments, with errors on the order of 0.06 ppm for exchange rates ranging from 100 to 1000 s{sup −1}, despite the small fraction of {sup 13}Cα–{sup 13}Cβ spin-pairs that are present for many residue types. The labeling approach described here should thus be attractive for studies of exchanging systems using {sup 13}Cα spin probes.

  4. Evaluation of a rabbit model for osteomyelitis by high field, high resolution imaging using the chemical-shift-specific-slice-selection technique.

    Science.gov (United States)

    Volk, A; Crémieux, A C; Belmatoug, N; Vallois, J M; Pocidalo, J J; Carbon, C

    1994-01-01

    The rabbit model of osteomyelitis introduced by C.W. Norden, based on injection of an infecting solution (Staphylococcus aureus, sodium morrhuate) into the tibia, was studied at 4.7 Tesla with a time-efficient chemical shift selective imaging technique, Chemical Shift Specific Slice Selection (C4S). The evolution of the disease over several weeks was followed on water-selective, fat-selective, and sum images obtained simultaneously with this imaging sequence. Experiments were performed either on different groups of rabbits at different times after infection with subsequent sacrifice of the animal and microbiological analysis of the infected tibia or on the same group of animals imaged several times after infection. Associated analysis of the water and fat selective images revealed marrow modifications very early (Day 5 after inoculation) demonstrating the high sensitivity of the employed imaging technique. Later on, bone modifications were best identified on the sum images. Additional experiments performed on animals injected with a noninfecting solution containing only sodium morrhuate showed however that the sclerosing agent alone can yield images similar to those produced by infection at early stages after inoculation. Therefore, the Norden model would not be suitable for monitoring quantitatively outcome of therapy by magnetic resonance imaging. It is however well adapted for the evaluation and optimization of MRI techniques or protocols intended to detect early changes of bone marrow produced by septic or aseptic infarct.

  5. Optical Red shift in ZnO Nanoflowers Fabricated on Non-Seeded Substrates by Soft Wet Chemical Route

    Science.gov (United States)

    Murali, K. V.; Preetha, K. C.; Ragina, A. J.; Deepa, K.; Remadevi, T. L.

    2011-10-01

    Zinc oxide (ZnO) nanoflowers were fabricated on non-seeded glass substrates by successive ionic layer adsorption and reaction (SILAR) method using different complex agents. Influence of complex agents ammonia, lithium hydroxide and hexamine on the optical properties of the as-synthesized and the samples annealed at 400 °C was studied. Optical red shift was observed in ZnO samples and was analyzed with respect to the complex agents. All samples possessed a steep absorption edge in the wavelength range 375-425 nm. ZnO nanostructures except that synthesized using hexamine have low and steady absorbance and show higher transmittance (70-85%) in the entire visible region. SEM, XRD and EDAX studies confirmed the high surface-to-volume ratio, good optical quality, excellent crystalline nature and purity of the formed and annealed ZnO nanostructures.

  6. Final Technical Report: A Paradigm Shift in Chemical Processing: New Sustainable Chemistries for Low-VOC Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Kenneth F.

    2006-07-26

    The project employed new processes to make emulsion polymers from reduced levels of petroleum-derived chemical feedstocks. Most waterborne paints contain spherical, emulsion polymer particles that serve as the film-forming binder phase. Our goal was to make emulsion polymer particles containing 30 percent feedstock that would function as effectively as commercial emulsions made from higher level feedstock. The processes developed yielded particles maintained their film formation capability and binding capacity while preserving the structural integrity of the particles after film formation. Rohm and Haas Company (ROH) and Archer Daniels Midland Company (ADM) worked together to employ novel polymer binders (ROH) and new, non-volatile, biomass-derived coalescing agents (ADM). The University of Minnesota Department of Chemical Engineering and Material Science utilized its unique microscopy capabilities to characterize films made from the New Emulsion Polymers (NEP).

  7. Comparison of clinical semi-quantitative assessment of muscle fat infiltration with quantitative assessment using chemical shift-based water/fat separation in MR studies of the calf of post-menopausal women

    Energy Technology Data Exchange (ETDEWEB)

    Alizai, Hamza; Nardo, Lorenzo; Karampinos, Dimitrios C.; Joseph, Gabby B.; Yap, Samuel P.; Baum, Thomas; Krug, Roland; Majumdar, Sharmila; Link, Thomas M. [University of California, San Francisco, Musculoskeletal and Quantitative Imaging Research Group, Department of Radiology and Biomedical Imaging, San Francisco, CA (United States)

    2012-07-15

    The goal of this study was to compare the semi-quantitative Goutallier classification for fat infiltration with quantitative fat-fraction derived from a magnetic resonance imaging (MRI) chemical shift-based water/fat separation technique. Sixty-two women (age 61 {+-} 6 years), 27 of whom had diabetes, underwent MRI of the calf using a T1-weighted fast spin-echo sequence and a six-echo spoiled gradient-echo sequence at 3 T. Water/fat images and fat fraction maps were reconstructed using the IDEAL algorithm with T2* correction and a multi-peak model for the fat spectrum. Two radiologists scored fat infiltration on the T1-weighted images using the Goutallier classification in six muscle compartments. Spearman correlations between the Goutallier grades and the fat fraction were calculated; in addition, intra-observer and inter-observer agreement were calculated. A significant correlation between the clinical grading and the fat fraction values was found for all muscle compartments (P < 0.0001, R values ranging from 0.79 to 0.88). Goutallier grades 0-4 had a fat fraction ranging from 3.5 to 19%. Intra-observer and inter-observer agreement values of 0.83 and 0.81 were calculated for the semi-quantitative grading. Semi-quantitative grading of intramuscular fat and quantitative fat fraction were significantly correlated and both techniques had excellent reproducibility. However, the clinical grading was found to overestimate muscle fat. (orig.)

  8. Pure magnetic hard fct FePt nanoparticles: Chemical synthesis, structural and magnetic properties correlations

    Energy Technology Data Exchange (ETDEWEB)

    Suber, L., E-mail: lorenza.suber@ism.cnr.it [ISM-CNR, Area della Ricerca di Roma 1, Via Salaria km 29.300, 00015 Monterotondo Scalo, RM (Italy); Marchegiani, G. [ISM-CNR, Area della Ricerca di Roma 1, Via Salaria km 29.300, 00015 Monterotondo Scalo, RM (Italy); Olivetti, E.S.; Celegato, F.; Coïsson, M.; Tiberto, P. [INRIM, Electromagnetism Division, Strada delle Cacce 91, 10135 Torino (Italy); Allia, P. [DISAT Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy); Barrera, G. [Dipartimento di Chimica, Università di Torino, Via Pietro Giuria 7, 10125 Torino (Italy); Pilloni, L. [UTTMAT-CHI, Via Anguillarese 10, 00123 S. Maria di Galeria, Roma (Italy); Barba, L. [IC-CNR, Area Science Park, SS 14 Km 163.5 Basovizza, 34149 Trieste (Italy); Padella, F. [UTTMAT-CHI, Via Anguillarese 10, 00123 S. Maria di Galeria, Roma (Italy); Cossari, P. [IGAG-CNR, Area della Ricerca di Roma 1, Via Salaria km 29.300, 00015 Monterotondo Scalo, RM (Italy); Chiolerio, A. [Istituto Italiano di Tecnologia, Center for Space Human Robotics, Corso Trento 21, 10129 Torino (Italy)

    2014-03-01

    FePt nanoparticles, containing a near-equal atomic percentage of Fe and Pt, with a face centered tetragonal structure (fct), are challenging for potential applications in high performance permanent magnets and high density data storage. In this study, we report on the chemical synthesis, carried out both solvothermally and hydrothermally in autoclave reacting iron (III) acetylacetonate and platinum (II) acetylacetonate with tri- or tetra-ethylene glycol, these employed as solvents, reducers and particle surface protecting agents as well. In both methods, a subsequent thermal treatment at high temperatures is necessary to transform the magnetic soft face centered cubic (fcc) phase to the hard fct one. Organic low-weight molecules, generally used to protect the nanoparticle surface and avoid particle aggregation, are decomposed by the thermal treatment resulting in particle aggregation and coalescence phenomena; on the contrary, in this case, a polymer matrix is formed as particle protecting agent and, by thermally treating the hydrothermally prepared nanoparticles up to 750 °C for 1 h, the pure magnetic hard fct phase is obtained while preserving the nanostructure. A detailed study is carried out on FePt nanoparticle structure (fcc and fct phases) and correlated to the magnetic properties of the system. - Highlights: • fct FePt nanoparticles for hard magnetic nanotechnology applications. • Influence of synthesis parameters on the precursor fcc FePt nanoparticle structure. • Easy hydrothermal method for preparing pure fct FePt nanoparticles. • Monitoring the role of temperature and time on the FePt fcc–fct phase transformation. • Correlation between FePt nanoparticle structural and magnetic properties.

  9. Chemical library screening for WNK signalling inhibitors using fluorescence correlation spectroscopy.

    Science.gov (United States)

    Mori, Takayasu; Kikuchi, Eriko; Watanabe, Yuko; Fujii, Shinya; Ishigami-Yuasa, Mari; Kagechika, Hiroyuki; Sohara, Eisei; Rai, Tatemitsu; Sasaki, Sei; Uchida, Shinichi

    2013-11-01

    WNKs (with-no-lysine kinases) are the causative genes of a hereditary hypertensive disease, PHAII (pseudohypoaldosteronism type II), and form a signal cascade with OSR1 (oxidative stress-responsive 1)/SPAK (STE20/SPS1-related proline/alanine-rich protein kinase) and Slc12a (solute carrier family 12) transporters. We have shown that this signal cascade regulates blood pressure by controlling vascular tone as well as renal NaCl excretion. Therefore agents that inhibit this signal cascade could be a new class of antihypertensive drugs. Since the binding of WNK to OSR1/SPAK kinases was postulated to be important for signal transduction, we sought to discover inhibitors of WNK/SPAK binding by screening chemical compounds that disrupt the binding. For this purpose, we developed a high-throughput screening method using fluorescent correlation spectroscopy. As a result of screening 17000 compounds, we discovered two novel compounds that reproducibly disrupted the binding of WNK to SPAK. Both compounds mediated dose-dependent inhibition of hypotonicity-induced activation of WNK, namely the phosphorylation of SPAK and its downstream transporters NKCC1 (Na/K/Cl cotransporter 1) and NCC (NaCl cotransporter) in cultured cell lines. The two compounds could be the promising seeds of new types of antihypertensive drugs, and the method that we developed could be applied as a general screening method to identify compounds that disrupt the binding of two molecules.

  10. Plant absorption of trace elements in sludge amended soils and correlation with soil chemical speciation

    Energy Technology Data Exchange (ETDEWEB)

    Torri, Silvana, E-mail: torri@agro.uba.ar [Catedra de Fertilidad y Fertilizantes, Facultad de Agronomia, UBA, Avda San Martin 4453, Buenos Aires (C1417 DSE) (Argentina); Lavado, Raul [Catedra de Fertilidad y Fertilizantes, Facultad de Agronomia, UBA, Avda San Martin 4453, Buenos Aires (C1417 DSE) (Argentina)

    2009-07-30

    The aim of the present study was to investigate the relationship between Lolium perenne L. uptake of Cd, Cu, Pb, and Zn in sludge amended soils and soil availability of these elements assessed by soil sequential extraction. A greenhouse experiment was set with three representative soils of the Pampas Region, Argentina, amended with sewage sludge and sewage sludge enriched with its own incinerated ash. After the stabilization period of 60 days, half of the pots were sampled for soil analysis; the rest of the pots were sown with L. perenne and harvested 8, 12, 16 and 20 weeks after sowing, by cutting just above the soil surface. Cadmium and Pb concentrations in aerial tissues of L. perenne were below detection limits, in good agreement with the soil fractionation study. Copper and Zn concentration in the first harvest were significantly higher in the coarse textured soil compared to the fine textured soil, in contrast with soil chemical speciation. In the third harvest, there was a positive correlation between Cu and Zn concentration in aerial biomass and soil fractions usually considered of low availability. We conclude that the most available fractions obtained by soil sequential extraction did not provide the best indicator of Cu and Zn availability to L. perenne.

  11. Structure-based predictions of 13C-NMR chemical shifts for a series of 2-functionalized 5-(methylsulfonyl)-1-phenyl-1H-indoles derivatives using GA-based MLR method

    Science.gov (United States)

    Ghavami, Raouf; Sadeghi, Faridoon; Rasouli, Zolikha; Djannati, Farhad

    2012-12-01

    Experimental values for the 13C NMR chemical shifts (ppm, TMS = 0) at 300 K ranging from 96.28 ppm (C4' of indole derivative 17) to 159.93 ppm (C4' of indole derivative 23) relative to deuteride chloroform (CDCl3, 77.0 ppm) or dimethylsulfoxide (DMSO, 39.50 ppm) as internal reference in CDCl3 or DMSO-d6 solutions have been collected from literature for thirty 2-functionalized 5-(methylsulfonyl)-1-phenyl-1H-indole derivatives containing different substituted groups. An effective quantitative structure-property relationship (QSPR) models were built using hybrid method combining genetic algorithm (GA) based on stepwise selection multiple linear regression (SWS-MLR) as feature-selection tools and correlation models between each carbon atom of indole derivative and calculated descriptors. Each compound was depicted by molecular structural descriptors that encode constitutional, topological, geometrical, electrostatic, and quantum chemical features. The accuracy of all developed models were confirmed using different types of internal and external procedures and various statistical tests. Furthermore, the domain of applicability for each model which indicates the area of reliable predictions was defined.

  12. Stereochemistry of Complex Marine Natural Products by Quantum Mechanical Calculations of NMR Chemical Shifts: Solvent and Conformational Effects on Okadaic Acid

    Directory of Open Access Journals (Sweden)

    Humberto J. Domínguez

    2014-01-01

    Full Text Available Marine organisms are an increasingly important source of novel metabolites, some of which have already inspired or become new drugs. In addition, many of these molecules show a high degree of novelty from a structural and/or pharmacological point of view. Structure determination is generally achieved by the use of a variety of spectroscopic methods, among which NMR (nuclear magnetic resonance plays a major role and determination of the stereochemical relationships within every new molecule is generally the most challenging part in structural determination. In this communication, we have chosen okadaic acid as a model compound to perform a computational chemistry study to predict 1H and 13C NMR chemical shifts. The effect of two different solvents and conformation on the ability of DFT (density functional theory calculations to predict the correct stereoisomer has been studied.

  13. Examination of anticipated chemical shift and shape distortion effect on materials commonly used in prosthetic socket fabrication when measured using MRI: a validation study.

    Science.gov (United States)

    Safari, Mohammad Reza; Rowe, Philip; Buis, Arjan

    2013-01-01

    The quality of lower-limb prosthetic socket fit is influenced by shape and volume consistency during the residual limb shape-capturing process (i.e., casting). Casting can be quantified with magnetic resonance imaging (MRI) technology. However, chemical shift artifact and image distortion may influence the accuracy of MRI when common socket/casting materials are used. We used a purpose-designed rig to examine seven different materials commonly used in socket fabrication during exposure to MRI. The rig incorporated glass marker tubes filled with water doped with 1 g/L copper sulfate (CS) and 9 plastic sample vials (film containers) to hold the specific material specimens. The specimens were scanned 9 times in different configurations. The absolute mean difference of the glass marker tube length was 1.39 mm (2.98%) (minimum = 0.13 mm [0.30%], maximum = 5.47 mm [14.03%], standard deviation = 0.89 mm). The absolute shift for all materials was <1.7 mm. This was less than the measurement tolerance of +/-2.18 mm based on voxel (three-dimensional pixel) dimensions. The results show that MRI is an accurate and repeatable method for dimensional measurement when using matter containing water. Additionally, silicone and plaster of paris plus 1 g/L CS do not show a significant shape distortion nor do they interfere with the MRI image of the residual limb.

  14. Examination of anticipated chemical shift and shape distortion effect on materials commonly used in prosthetic socket fabrication when measured using MRI: A validation study

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Safari, PhD

    2013-02-01

    Full Text Available The quality of lower-limb prosthetic socket fit is influenced by shape and volume consistency during the residual limb shape-capturing process (i.e., casting. Casting can be quantified with magnetic resonance imaging (MRI technology. However, chemical shift artifact and image distortion may influence the accuracy of MRI when common socket/casting materials are used. We used a purpose-designed rig to examine seven different materials commonly used in socket fabrication during exposure to MRI. The rig incorporated glass marker tubes filled with water doped with 1 g/L copper sulfate (CS and 9 plastic sample vials (film containers to hold the specific material specimens. The specimens were scanned 9 times in different configurations. The absolute mean difference of the glass marker tube length was 1.39 mm (2.98% (minimum = 0.13 mm [0.30%], maximum = 5.47 mm [14.03%], standard deviation = 0.89 mm. The absolute shift for all materials was <1.7 mm. This was less than the measurement tolerance of +/–2.18 mm based on voxel (three-dimensional pixel dimensions. The results show that MRI is an accurate and repeatable method for dimensional measurement when using matter containing water. Additionally, silicone and plaster of paris plus 1 g/L CS do not show a significant shape distortion nor do they interfere with the MRI image of the residual limb.

  15. A stochastic chemical dynamic approach to correlate autoimmunity and optimal vitamin-D range.

    Directory of Open Access Journals (Sweden)

    Susmita Roy

    Full Text Available Motivated by several recent experimental observations that vitamin-D could interact with antigen presenting cells (APCs and T-lymphocyte cells (T-cells to promote and to regulate different stages of immune response, we developed a coarse grained but general kinetic model in an attempt to capture the role of vitamin-D in immunomodulatory responses. Our kinetic model, developed using the ideas of chemical network theory, leads to a system of nine coupled equations that we solve both by direct and by stochastic (Gillespie methods. Both the analyses consistently provide detail information on the dependence of immune response to the variation of critical rate parameters. We find that although vitamin-D plays a negligible role in the initial immune response, it exerts a profound influence in the long term, especially in helping the system to achieve a new, stable steady state. The study explores the role of vitamin-D in preserving an observed bistability in the phase diagram (spanned by system parameters of immune regulation, thus allowing the response to tolerate a wide range of pathogenic stimulation which could help in resisting autoimmune diseases. We also study how vitamin-D affects the time dependent population of dendritic cells that connect between innate and adaptive immune responses. Variations in dose dependent response of anti-inflammatory and pro-inflammatory T-cell populations to vitamin-D correlate well with recent experimental results. Our kinetic model allows for an estimation of the range of optimum level of vitamin-D required for smooth functioning of the immune system and for control of both hyper-regulation and inflammation. Most importantly, the present study reveals that an overdose or toxic level of vitamin-D or any steroid analogue could give rise to too large a tolerant response, leading to an inefficacy in adaptive immune function.

  16. 2D 1H -13C Heteronuclear Shift Correlation Of 2a - Hydroxy Aiantolactone From Pulicaria Undulata C.A. Mey

    Directory of Open Access Journals (Sweden)

    A. Rustaiyan

    1992-07-01

    Full Text Available We have reported recently the isolation and characterization of several sesquiterpene lactones from Pulicaria undulata (1."nThe lactones were isolated from an Et20 - Petrol (1:3 fraction by different chromatographic techniques including HPLC (RP 8, MeOH - H2O, 13:7."nIn this way three eudesmanolides 1 - 3, a guaianolide 4, a nor -guaianolide 5, as well as the pseudoguaianolide 6 and the xanthanolide 7 were isolated. One of the eudesmanolides (2a - hydroxy aiantolactone, 1, was present as the main component."nSuch lactones being known as biologically active substances, we have decided to describe for the first time a detailed interpretation of proton, 1H -NMR, 13C - NMR and 2D lH -13C - heteronuclear shift correlation spectra of 2a - hydroxy aiantolactone. The stereochemistry of C - 2 , C - 7 and C - 8 was determined by the NOESY experiments, H - 7 and H - 8 are in the a configuration and H - 2 is in the b configuration.

  17. Chemical profiling and classification of illicit heroin by principal component analysis, calculation of inter sample correlation and artificial neural networks.

    Science.gov (United States)

    Esseiva, Pierre; Anglada, Frederic; Dujourdy, Laurence; Taroni, Franco; Margot, Pierre; Pasquier, Eric Du; Dawson, Michael; Roux, Claude; Doble, Philip

    2005-08-15

    Artificial neural networks (ANNs) were utilised to validate illicit drug classification in the profiling method used at "Institut de Police Scientifique" of the University of Lausanne (IPS). This method established links between samples using a combination of principal component analysis (PCA) and calculation of a correlation value between samples. Heroin seizures sent to the IPS laboratory were analysed using gas chromatography (GC) to separate the major alkaloids present in illicit heroin. Statistical analysis was then performed on 3371 samples. Initially, PCA was performed as a preliminary screen to identify samples of a similar chemical profile. A correlation value was then calculated for each sample previously identified with PCA. This correlation value was used to determine links between drug samples. These links were then recorded in an Ibase((R)) database. From this database the notion of "chemical class" arises, where samples with similar chemical profiles are grouped together. Currently, about 20 "chemical classes" have been identified. The normalised peak areas of six target compounds were then used to train an ANN to classify each sample into its appropriate class. Four hundred and sixty-eight samples were used as a training data set. Sixty samples were treated as blinds and 370 as non-linked samples. The results show that in 96% of cases the neural network attributed the seizure to the right "chemical class". The application of a neural network was found to be a useful tool to validate the classification of new drug seizures in existing chemical classes. This tool should be increasingly used in such situations involving profile comparisons and classifications.

  18. Correlating the nanoscale mechanical and chemical properties of knockout mice bones

    Science.gov (United States)

    Kavukcuoglu, Nadire Beril

    Bone is a mineral-organic composite where the organic matrix is mainly type I collagen plus small amounts of non-collagenous proteins including osteopontin (OPN), osteocalcin (OC) and fibrillin 2 (Fbn2). Mature bone undergoes remodeling continually so new bone is formed and old bone resorbed. Uncoupling between the bone resorption and bone formation causes an overall loss of bone mass and leads to diseases like osteoporosis and osteopenia. These are characterized by structural deterioration of the bone tissue and an increased risk of fracture. The non-collagenous bone proteins are known to have a role in regulating bone turnover and to affect the structural integrity of bone. OPN and OC play a key role in bone resorption and formation, while absence of Fbn-2 causes a connective tissue disorder (congenital contractural arachnodactyly) and has been associated with decreased bone mass. In this thesis nanoindentation and Raman-microspectroscopy techniques were used to investigate and correlate the mechanical and chemical properties of cortical femoral bones from OPN deficient (OPN-/-), OC deficient (OC-/-) and Fbn-2 deficient (Fbn2-/-) mice and their age, sex and background matched wild-type controls (OPN+/+, OC+/+ and Fbn2+/+). For OPN the hardness (H) and elastic modulus (E) of under 12 week OPN-/- bones were significantly lower than for OPN+/+ bones, but Raman showed no significant difference. Mechanical properties of bones from mice older than 12 weeks were not significantly different with genotype. However, mineralization and crystallinity from >50 week OPN-/- bones were significantly higher than for OPN+/+ bones. Mechanical properties of OPN-/- bones showed no variation with age, but mineralization, crystallinity and type-B carbonate substitution increased for both genotypes. For OC-/- intra-bone analyses showed that the hardness and crystallinity of the bones were significantly higher, especially in the mid-cortical sections, compared to OC+/+ bones. Fbn2

  19. Measurement of the principal values of the chemical-shift tensors of overlapping protonated and unprotonated carbons with the 2D-SUPER technique and dipolar dephasing (DD-SUPER)

    Science.gov (United States)

    Liu, Wei; Wang, Wei D.; Wang, Wei; Bai, Shi; Dybowski, Cecil

    2010-09-01

    A modified 2D-SUPER technique is demonstrated to allow independent measurement of the principal values of the chemical-shift tensors of overlapping protonated and unprotonated carbons. The insertion of a dipolar-dephasing period into the sequence causes loss of signal from protonated carbons. The spectrum obtained with this modification allows one to determine the principal values of the unprotonated carbons with high precision. Subsequent fitting of the usual 2D-SUPER spectrum, with the chemical-shift parameters of the unprotonated carbons fixed, gives the parameters of the overlapped resonances of the protonated carbons. As an example, we report the determination of the 13C chemical-shift parameters of the carbons of form II of piroxicam. The experimental results are compared with those obtained from calculations using the DFT/GIAO method. Potential applications of this method are discussed.

  20. The test-particle induced inhomogeneous direct correlation functions and extensions of Widom's theorem: impacts on the incremental chemical potentials and high-order correlation functions.

    Science.gov (United States)

    Lee, Lloyd L

    2013-10-21

    We develop the potential distributions of several test particles to obtain a hierarchy of the nonuniform singlet direct correlation functions (s-DCFs). These correlation functions are interpreted as the segmental chemical potentials or works of insertion of successive test particles in a classical fluid. The development has several interesting consequences: (i) it extends the Widom particle insertion formula to higher-order theorems, the first member gives the chemical potential as in the original theorem, the second member gives the incremental energy for dimer formation, with higher members giving the energies for forming trimers, tetramers, etc. (ii) The second and third order s-DCFs can be related to the cavity distribution functions y((2)) and y((3)) in the liquid-state theory. Thus we can express the triplet cavity function y((3)) in terms of these s-DCFs in an exact form. This enables us to calculate, as an illustration of the above theoretical developments, the numerical values of the s-DCFs via Monte Carlo (MC) simulation data on hard spheres. We use these data to critically analyze the commonly used approximations, the Kirkwood superposition (KSA) and the linear approximation (LA) for triplet correlation functions. An improved rule over KSA and LA is proposed for triplet hard spheres in the rolling-contact configurations. (iii) The s-DCFs are naturally suited for analyzing the chain-incremental Ansatz or hypothesis in the calculation of the chemical potentials of polymeric chain molecules. The first few segments of a polymer chain have been shown from extensive Monte Carlo simulations to not obey this Ansatz. By examining the insertion energies of successive segments through the s-DCFs, we are able to quantitatively decipher the decay of the segmental chemical potentials for at least the first three segments. Comparison with MC data on 4-mer and 8-mer hard-sphere fluids shows commensurate behavior with the s-DCFs. In addition, an analytical density

  1. The effects of librations on the 13C chemical shift and 2H electric field gradient tensors in β-calcium formate

    Science.gov (United States)

    Hallock, Kevin J.; Lee, Dong Kuk; Ramamoorthy, A.

    2000-12-01

    The magnitudes and orientations of the principal elements of the 13C chemical shift anisotropy (CSA) tensor in the molecular frame of the formate ion in β-calcium formate is determined using one-dimensional dipolar-shift spectroscopy. The magnitudes of the principal elements of the 13C CSA tensor are σ11C=104 ppm, σ22C=179 ppm, and σ33C=233 ppm. The least shielding element of the 13C CSA tensor, σ33C, is found to be collinear with the C-H bond. The temperature dependence of the 13C CSA and the 2H quadrupole coupling tensors in β-calcium formate are analyzed for a wide range of temperature (173-373 K). It was found that the span of the 13C CSA and the magnitude of the 2H quadrupole coupling interactions are averaged with the increasing temperature. The experimental results also show that the 2H quadrupole coupling tensor becomes more asymmetric with increasing temperature. A librational motion about the σ22C axis of the 13C CSA tensor is used to model the temperature dependence of the 13C CSA tensor. The temperature dependence of the mean-square amplitude of the librational motion is found to be =2.6×10-4(T) rad2 K-1. The same librational motion also accounts for the temperature-dependence of the 2H quadrupole coupling tensor after the relative orientation of the 13C CSA and 2H electric field gradient tensors are taken into account. Reconsideration of the results of a previous study found that the librational motion, not the vibrational motion, accounts for an asymmetry in the 1H-13C dipolar coupling tensor of α-calcium formate at room temperature.

  2. A lanthanide complex with dual biosensing properties: CEST (chemical exchange saturation transfer) and BIRDS (biosensor imaging of redundant deviation in shifts) with europium DOTA-tetraglycinate.

    Science.gov (United States)

    Coman, Daniel; Kiefer, Garry E; Rothman, Douglas L; Sherry, A Dean; Hyder, Fahmeed

    2011-12-01

    Responsive contrast agents (RCAs) composed of lanthanide(III) ion (Ln3R) complexes with a variety of1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate (DOTA4S) derivatives have shown great potential as molecular imaging agents for MR. A variety of LnDOTA–tetraamide complexes have been demonstrated as RCAs for molecular imaging using chemical exchange saturation transfer (CEST). The CEST method detects proton exchange between bulk water and any exchangeable sites on the ligand itself or an inner sphere of bound water that is shifted by a paramagnetic Ln3R ion bound in the core of the macrocycle. It has also been shown that molecular imaging is possible when the RCA itself is observed (i.e. not its effect on bulk water) using a method called biosensor imaging of redundant deviation in shifts (BIRDS). The BIRDS method utilizes redundant information stored in the nonexchangeable proton resonances emanating from the paramagnetic RCA for ambient factors such as temperature and/or pH.Thus, CEST and BIRDS rely on exchangeable and nonexchangeable protons, respectively, for biosensing. We posited that it would be feasible to combine these two biosensing features into the same RCA (i.e. dual CEST and BIRDS properties). A complex between europium(III) ion (Eu3R) and DOTA–tetraglycinate [DOTA–(gly)S4] was used to demonstrate that its CEST characteristics are preserved, while its BIRDS properties are also detectable. The in vitro temperature sensitivity of EuDOTA–(gly)S4 was used to show that qualitative MR contrast with CEST can be calibrated using quantitative MR mapping with BIRDS, thereby enabling quantitative molecular imaging at high spatial resolution.

  3. Concurrent Increases and Decreases in Local Stability and Conformational Heterogeneity in Cu, Zn Superoxide Dismutase Variants Revealed by Temperature-Dependence of Amide Chemical Shifts.

    Science.gov (United States)

    Doyle, Colleen M; Rumfeldt, Jessica A; Broom, Helen R; Sekhar, Ashok; Kay, Lewis E; Meiering, Elizabeth M

    2016-03-08

    The chemical shifts of backbone amide protons in proteins are sensitive reporters of local structural stability and conformational heterogeneity, which can be determined from their readily measured linear and nonlinear temperature-dependences, respectively. Here we report analyses of amide proton temperature-dependences for native dimeric Cu, Zn superoxide dismutase (holo pWT SOD1) and structurally diverse mutant SOD1s associated with amyotrophic lateral sclerosis (ALS). Holo pWT SOD1 loses structure with temperature first at its periphery and, while having extremely high global stability, nevertheless exhibits extensive conformational heterogeneity, with ∼1 in 5 residues showing evidence for population of low energy alternative states. The holo G93A and E100G ALS mutants have moderately decreased global stability, whereas V148I is slightly stabilized. Comparison of the holo mutants as well as the marginally stable immature monomeric unmetalated and disulfide-reduced (apo(2SH)) pWT with holo pWT shows that changes in the local structural stability of individual amides vary greatly, with average changes corresponding to differences in global protein stability measured by differential scanning calorimetry. Mutants also exhibit altered conformational heterogeneity compared to pWT. Strikingly, substantial increases as well as decreases in local stability and conformational heterogeneity occur, in particular upon maturation and for G93A. Thus, the temperature-dependence of amide shifts for SOD1 variants is a rich source of information on the location and extent of perturbation of structure upon covalent changes and ligand binding. The implications for potential mechanisms of toxic misfolding of SOD1 in disease and for general aspects of protein energetics, including entropy-enthalpy compensation, are discussed.

  4. Correlation between magnetic spin structure and the three-dimensional geometry in chemically synthesized nanoscale magnetite rings

    DEFF Research Database (Denmark)

    Eltschka, M.; Klaui, M.; Rudiger, U;

    2008-01-01

    The correlation between magnetic spin structure and geometry in nanoscale chemically synthesized Fe3O4 rings has been investigated by transmission electron microscopy. We find primarily the flux closure vortex states but in rings with thickness variations, an effective stray field occurs. Using....... The interaction between exchange coupled rings leads to antiparallel vortex states and extended onion states. (c) 2008 American Institute of Physics....

  5. Chemical constituents of Ottonia corcovadensis Miq. from Amazon forest: {sup 1}H and {sup 13}C chemical shift assignments; Constituintes quimicos de Ottonia corcovadensis Miq. da floresta Amazonica - atribuicao dos deslocamentos quimicos dos atomos de hidrogenio e carbono

    Energy Technology Data Exchange (ETDEWEB)

    Facundo, Valdir A. [Rondonia Univ., Porto Velho, RO (Brazil). Dept. de Quimica; Morais, Selene M. [Ceara Univ., Fortaleza, CE (Brazil). Dept. de Quimica e Fisica; Braz Filho, Raimundo [Universidade Estadual do Norte Fluminense (UENF), Campos dos Goytacases, RJ (Brazil). Setor de Quimica de Produtos Naturais. Lab. de Ciencias Quimicas. Setor de Quimica de Produtos Naturais]. E-mail: braz@uenf.br

    2004-02-01

    In an ethanolic extract of leaves of Ottonia corcovadensis (Piperaceae) were identified sixteen terpenoids of essential oil and the three flavonoids 3',4',5,5',7-penta methoxyflavone (1), 3',4',5,7-tetra methoxyflavone (2) and 5-hydroxy-3',4',5',7-tetra methoxyflavone (3) and cafeic acid (4). Two amides (5 and 6) were isolated from an ethanolic extract of the roots. The structures were established by spectral analysis, meanly NMR (1D and 2D) and mass spectra. Extensive NMR analysis was also used to complete {sup 1}H and {sup 13}C chemical shift assignments of the flavonoids and amides. The components of the essential oil were identified by computer library search, retention indices and visual interpretation of mass spectra. (author)

  6. Determination of the Orientation and Dynamics of Ergosterol in Model Membranes Using Uniform 13C Labeling and Dynamically Averaged 13C Chemical Shift Anisotropies as Experimental Restraints

    Science.gov (United States)

    Soubias, O.; Jolibois, F.; Massou, S.; Milon, A.; Réat, V.

    2005-01-01

    A new strategy was established to determine the average orientation and dynamics of ergosterol in dimyristoylphosphatidylcholine model membranes. It is based on the analysis of chemical shift anisotropies (CSAs) averaged by the molecular dynamics. Static 13C CSA tensors were computed by quantum chemistry, using the gauge-including atomic-orbital approach within Hartree-Fock theory. Uniformly 13C-labeled ergosterol was purified from Pichia pastoris cells grown on labeled methanol. After reconstitution into dimyristoylphosphatidylcholine lipids, the complete 1H and 13C assignment of ergosterol's resonances was performed using a combination of magic-angle spinning two-dimensional experiments. Dynamically averaged CSAs were determined by standard side-band intensity analysis for isolated 13C resonances (C3 and ethylenic carbons) and by off-magic-angle spinning experiments for other carbons. A set of 18 constraints was thus obtained, from which the sterol's molecular order parameter and average orientation could be precisely defined. The validity of using computed CSAs in this strategy was verified on cholesterol model systems. This new method allowed us to quantify ergosterol's dynamics at three molar ratios: 16 mol % (Ld phase), 30 mol % (Lo phase), and 23 mol % (mixed phases). Contrary to cholesterol, ergosterol's molecular diffusion axis makes an important angle (14°) with the inertial axis of the rigid four-ring system. PMID:15923221

  7. ¹³C solid-state NMR analysis of the most common pharmaceutical excipients used in solid drug formulations, Part I: Chemical shifts assignment.

    Science.gov (United States)

    Pisklak, Dariusz Maciej; Zielińska-Pisklak, Monika Agnieszka; Szeleszczuk, Łukasz; Wawer, Iwona

    2016-04-15

    Solid-state NMR is an excellent and useful method for analyzing solid-state forms of drugs. In the (13)C CP/MAS NMR spectra of the solid dosage forms many of the signals originate from the excipients and should be distinguished from those of active pharmaceutical ingredient (API). In this work the most common pharmaceutical excipients used in the solid drug formulations: anhydrous α-lactose, α-lactose monohydrate, mannitol, sucrose, sorbitol, sodium starch glycolate type A and B, starch of different origin, microcrystalline cellulose, hypromellose, ethylcellulose, methylcellulose, hydroxyethylcellulose, sodium alginate, magnesium stearate, sodium laurilsulfate and Kollidon(®) were analyzed. Their (13)C CP/MAS NMR spectra were recorded and the signals were assigned, employing the results (R(2): 0.948-0.998) of GIPAW calculations and theoretical chemical shifts. The (13)C ssNMR spectra for some of the studied excipients have not been published before while for the other signals in the spectra they were not properly assigned or the assignments were not correct. The results summarize and complement the data on the (13)C ssNMR analysis of the most common pharmaceutical excipients and are essential for further NMR studies of API-excipient interactions in the pharmaceutical formulations.

  8. Scan time reduction in {sup 23}Na-Magnetic Resonance Imaging using the chemical shift imaging sequence. Evaluation of an iterative reconstruction method

    Energy Technology Data Exchange (ETDEWEB)

    Weingaertner, Sebastian; Konstandin, Simon; Schad, Lothar R. [Heidelberg Univ., Mannheim (Germany). Computer Assisted Clinical Medicine; Wetterling, Friedrich [Heidelberg Univ., Mannheim (Germany). Computer Assisted Clinical Medicine; Dublin Univ. (Ireland) Trinity Inst. of Neuroscience; Fatar, Marc [Heidelberg Univ., Mannheim (Germany). Dept. of Neurology; Neumaier-Probst, Eva [Heidelberg Univ., Mannheim (Germany). Dept. of Neuroradiology

    2015-07-01

    To evaluate potential scan time reduction in {sup 23}Na-Magnetic Resonance Imaging with the chemical shift imaging sequence (CSI) using undersampled data of high-quality datasets, reconstructed with an iterative constrained reconstruction, compared to reduced resolution or reduced signal-to-noise ratio. CSI {sup 23}Na-images were retrospectively undersampled and reconstructed with a constrained reconstruction scheme. The results were compared to conventional methods of scan time reduction. The constrained reconstruction scheme used a phase constraint and a finite object support, which was extracted from a spatially registered {sup 1}H-image acquired with a double-tuned coil. The methods were evaluated using numerical simulations, phantom images and in-vivo images of a healthy volunteer and a patient who suffered from cerebral ischemic stroke. The constrained reconstruction scheme showed improved image quality compared to a decreased number of averages, images with decreased resolution or circular undersampling with weighted averaging for any undersampling factor. Brain images of a stroke patient, which were reconstructed from three-fold undersampled k-space data, resulted in only minor differences from the original image (normalized root means square error < 12%) and an almost identical delineation of the stroke region (mismatch < 6%). The acquisition of undersampled {sup 23}Na-CSI images enables up to three-fold scan time reduction with improved image quality compared to conventional methods of scan time saving.

  9. Study on Model of Correlation Between Chemical Element Contents in Tree Rings and Soils near Tree Roots

    Institute of Scientific and Technical Information of China (English)

    KESHAN-ZHE; QIANJUN-LONG; 等

    1994-01-01

    The chemical element contents in tree rings are correlated with those in the soils near the tree roots,The results in the present study showed that the correlation between them could be described using the following logarithmic linear correlation model:lgC'(Z)=a(Z)+b(Z)lgC(Z).Therefor,by determining the chrono-sequence C(Z,t),where Z is the atomic number and t the year,of elemental contents in the annual growth rings of trees,we could get the chrono-sequence C'(Z,t) of elemental contents in the soil,thus inferring the dynaminc variations of relevant elemental contents in the soil.

  10. CANONICAL CORRELATION OF PHYSICAL AND CHEMICAL CHARACTERISTICS OF THE WOOD OF Eucalyptus grandis AND Eucalyptus saligna CLONES

    Directory of Open Access Journals (Sweden)

    Paulo Fernando Trugilho

    2003-01-01

    Full Text Available The analysis of canonical correlation measures the existence and the intensity of the association between two groups of variables. The research objectified to evaluate thecanonical correlation between chemical and physical characteristics and fiber dimensional ofwood of Eucalyptus grandis and Eucalyptus saligna clones, verifying the interdependenceamong the groups of studied variables. The analysis indicated that the canonical correlationswere high and that in two cases the first and second pair were significant at the level of 1% ofprobability. The analysis of canonical correlation showed that the groups are notindependent. The intergroup associations indicated that the wood of high insoluble lignin contentand low ash content is associated with the high radial and tangential contraction and highbasic density wood.

  11. Changes of Polyphenols in Tobacco Leaves During the Flue-Curing Process and Correlation Analysis on Some Chemical Components

    Institute of Scientific and Technical Information of China (English)

    GONG Chang-rong; WANG Ai-hua; WANG Song-feng

    2006-01-01

    The changes of polyphenols in tobacco leaves during the flue-curing process and correlation analysis on some chemical components were studied. Leaf samples were taken from different tobacco-producing regions in Henan Province, China.The results indicated that the content of total phenols increased during the first 24 h of curing, and then decreased. It reached the lowest value at 72 h of curing and increased rapidly after that. The content of chlorogenic acid also increased during 0-24 h of curing. But the lowest point occurred at 60 or 72 h of curing and then it increased till the end of the curing process. The content of rutin generally increased with curing, and showed little fluctuations. The changes of PPO and POD activity were the opposite. Rutin was found to have a highly significant positive correlation with total sugar (r=0.822**),but a highly significant negative correlation with starch, nicotine, and protein.

  12. Study of the correlation between columnar aerosol burden, suspended matter at ground and chemical components in a background European environment

    Science.gov (United States)

    EstelléS, VíCtor; MartíNez-Lozano, José A.; Pey, Jorge; Sicard, MichaëL.; Querol, Xavier; Esteve, Anna R.; Utrillas, MaríA. P.; Sorribas, Mar; Gangoiti, Gotzon; Alastuey, AndréS.; Rocadenbosch, Francesc

    2012-02-01

    Although routinely monitored by ground based air quality networks, the particulate matter distribution could be eventually better described with remote sensing techniques. However, valid relationships between ground level and columnar ground based quantities should be known beforehand. In this study we have performed a comparison between particulate matter measurements at ground level at different cut sizes (10, 2.5 and 1.0 μm), and the aerosol optical depth obtained by means of a ground based sunphotometer during a multiinstrumental field campaign held in El Arenosillo (Huelva, Spain) from 28 June to 4 July 2006. All the PM fractions were very well correlated with AOD with correlation coefficients that ranged from 0.71 to 0.81 for PM10, PM2.5 and PM1. Furthermore, the influence of the mixing layer height in the correlations was explored. The improvement in the correlation when the vertical distribution is taken into account was significant for days with a homogeneous mixing layer. Moreover, the chemical analysis of the individual size fractions allowed us to study the origin of the particulate matter. Secondary components were the most abundant and also well correlated in the three size fractions; but for PM10 fraction, chemical species related to marine origin were best correlated. Finally, we obtained a relationship between MODIS L3 AOD from collection 5.1 and the three PM cut sizes. In spite of being a relatively clean environment, all the techniques were able to capture similar day to day variations during this field campaign.

  13. Determination of the Tautomeric Equilibria of Pyridoyl Benzoyl -Diketones in the Liquid and Solid State through the use of Deuterium Isotope Effects on 1H and 13C NMR Chemical Shifts and Spin Coupling Constants

    DEFF Research Database (Denmark)

    Hansen, Poul Erik; Borisov, Eugeny V.; Lindon, John C.

    2015-01-01

    The tautomeric equilibria for 2-pyridoyl-, 3-pyridoyl-, and 4-pyridoyl-benzoyl methane have been investigated using deuterium isotope effects on 1H and 13C chemical shifts both in the liquid and the solid state. Equilibria are established both in the liquid and the solid state. In addition, in th...

  14. Comparison of brown and white adipose tissue fat fractions in ob, seipin, and Fsp27 gene knockout mice by chemical shift-selective imaging and (1)H-MR spectroscopy.

    Science.gov (United States)

    Peng, Xin-Gui; Ju, Shenghong; Fang, Fang; Wang, Yu; Fang, Ke; Cui, Xin; Liu, George; Li, Peng; Mao, Hui; Teng, Gao-Jun

    2013-01-15

    Brown adipose tissue (BAT) plays a key role in thermogenesis to protect the body from cold and obesity. White adipose tissue (WAT) stores excess energy in the form of triglycerides. To better understand the genetic effect on regulation of WAT and BAT, we investigated the fat fraction (FF) in two types of adipose tissues in ob/ob, human BSCL2/seipin gene knockout (SKO), Fsp27 gene knockout (Fsp27(-/-)), and wild-type (WT) mice in vivo using chemical shift selective imaging and (1)H-MR spectroscopy. We reported that the visceral fat volume in WAT was significantly larger in ob/ob mice, but visceral fat volumes were lower in SKO and Fsp27(-/-) mice compared with WT mice. BAT FF was significantly higher in ob/ob mice than the WT group and similar to that of WAT. In contrast, WAT FFs in SKO and Fsp27(-/-) mice were lower and similar to that of BAT. The adipocyte size of WAT in ob/ob mice and the BAT adipocyte size in ob/ob, SKO, and Fsp27 mice were significantly larger compared with WT mice. However, the WAT adipocyte size was significantly smaller in SKO mice than in WT mice. Positive correlations were observed between the adipocyte size and FFs of WAT and BAT. These results suggested that smaller adipocyte size correlates with lower FFs of WAT and BAT. In addition, the differences in FFs in WAT and BAT measured by MR methods in different mouse models were related to the different regulation effects of ob, seipin, or Fsp27 gene on developing WAT and BAT.

  15. Shifting Attention

    Science.gov (United States)

    Ingram, Jenni

    2014-01-01

    This article examines the shifts in attention and focus as one teacher introduces and explains an image that represents the processes involved in a numeric problem that his students have been working on. This paper takes a micro-analytic approach to examine how the focus of attention shifts through what the teacher and students do and say in the…

  16. Tough Shift

    DEFF Research Database (Denmark)

    Brewer, Robert S.; Verdezoto, Nervo; Holst, Thomas;

    2015-01-01

    in a student dormitory and found that players did not shift their electricity use, because they were unwilling to change their schedules and found it easier to focus on reducing electricity use. Based on our findings, we discuss the implications for encouraging shifting, and also the challenges of integrating...

  17. Lack of contralateral suppression in transient-evoked otoacoustic emissions in multiple chemical sensitivity: a clinical correlation study

    Directory of Open Access Journals (Sweden)

    Alessandro Micarelli

    2016-01-01

    Full Text Available Multiple chemical sensitivity (MCS is a chronic disorder characterized by a variety of symptoms associated with the exposure to chemicals at a concentration below the toxic level. Previous studies have demonstrated peculiar responses in brain activity in these patients with respect to sensory stimuli while the association between chemical sensitivity and other environmental intolerances such as noise sensitivity has been questioned by researchers. In this study, a cohort of 18 MCS patients underwent transient-evoked otoacoustic emission (TEOAE testing with and without contralateral suppression to evaluate the functionality of the medial olivocochlear (MOC reflex involved in speech-in-noise sensitivity. Results were compared with an age- and gender-matched control group (n = 20 and correlation analysis with disease onset and quick environmental exposure sensitivity inventory (qEESI symptom severity scale was performed. Subjects affected by MCS showed statistically significant impairment of MOC reflex, and the onset of the disease and several symptom subscales showed to be correlated to such reduction in some of the frequencies tested. These data suggest that alterations of MOC reflex could be part of the complex features of this disease although more studies are needed to further explore auditory perception disorders in environmental intolerances.

  18. Correlating chemical sensitivity and basal gene expression reveals mechanism of action | Office of Cancer Genomics

    Science.gov (United States)

    Changes in cellular gene expression in response to small-molecule or genetic perturbations have yielded signatures that can connect unknown mechanisms of action (MoA) to ones previously established. We hypothesized that differential basal gene expression could be correlated with patterns of small-molecule sensitivity across many cell lines to illuminate the actions of compounds whose MoA are unknown.

  19. HONEYDEW HONEY: CORRELATIONS BETWEEN CHEMICAL COMPOSITION, ANTIOXIDANT CAPACITY AND ANTIBACTERIAL EFFECT

    Directory of Open Access Journals (Sweden)

    OTILIA BOBIS

    2013-12-01

    Full Text Available Selected physico-chemical parameters, total polyphenols, flavonoids, antioxidant and antibacterial activity of honeydew honey samples from Romanian were determined. Regarding the chemical composition, analysed honey samples framed in this type of honey, phenolic content, determined as gallic acid equivalents, presented a mean value of 116.45mg GAE/100 g honey. Total flavonoid content expressed as quercetin equivalents, was 1.53 mg in honeydew honey. Antioxidant activity expressed as % inhibition of a solution of DPPH, ranged between 47.84 and 62.99%. The concentration of honey that inhibit with 50% the DPPH solution was established to be 16.16%. 10 strains of Staphylococcus aureus presented different inhibition percentages when were treatred with a solution of honey. In conclusion, Honeydew honey could be recommended to complement other polyphenol source in human diet and also used in medical treatment.

  20. Correlation of urinary thioethers with chemical exposure in a rubber plant.

    Science.gov (United States)

    Kilpikari, I

    1981-01-01

    Exposure to potentially alkylating in a rubber factory was measured by determining thioether concentrations in urine samples collected at the end of work on a Friday. The study population consisted of the total work force (113) in the production departments of a factory, and office clerks (111) in two factories of the same company. The highest excretion of thioethers was detected in female workers in the belt department who were exposed through the palmar skin. High excretion was also found in workers exposed to air-borne contaminants in the calender department and in workers in the raw material stores and chemical mixing sections. Lower values were found in this dispatching station and in the contaminant-free offices. Urinary thioether determination appears to be a reliable and easy method of assessing the exposure to certain rubber chemicals. PMID:7470409

  1. In vitro crude protein digestibility of Tenebrio molitor and Hermetia illucens insect meals and its correlation with chemical composition traits

    Directory of Open Access Journals (Sweden)

    Stefania Marono

    2015-07-01

    Full Text Available The aims of this study were to evaluate the correlation between in vitro crude protein digestibility coefficients of insect meals from Tenebrio molitor (TI and Hermetia illucens (HI and their chemical composition traits as well as to develop regression equations able to estimate the in vitro crude protein digestibility (CPd from proximate analysis of insect meals. Twelve samples of insect meals (6 from TM larvae, TM 1-6 and 6 from HI larvae, HI 1-6 were obtained from different producers and analysed for chemical composition and in vitro crude protein digestibility by a two-step enzymatic method (digestion with pepsin and trypsin-enriched pancreatin. For both insect meal samples, CPd was negatively correlated to ADF and chitin contents, while just for HI there was a positive correlation (P<0.01 between CP percentage of the samples and CPd. For both insect meals the former variable chosen in the stepwise analysis was the chitin, explaining the 79.45% of CPd variability for Tenebrio molitor samples and the 98.30% for Hermetia illucens. In the second step, the amount of protein linked to ADF was added in the model for T. molitor and CP for H. illucens samples. The coefficients chitin is the main constituent of insect body able to affect the crude protein digestibility of Tenebrio molitor and Hermetia illucens larvae meals estimated by an in vitro enzymatic method.

  2. FONO: a difficult case for theory. The ELF and ELI-D topological studies on the chemical bonding using correlated wavefunctions.

    Science.gov (United States)

    Berski, Slawomir; Gordon, Agnieszka J; Latajka, Zdzislaw

    2013-04-01

    The complicated nature of the chemical bonding in cis and trans isomers of F-O-N=O is discussed based on the results obtained from the topological analysis of electron localization function (η) (ELF), electron localizability index (Y(D)(σ)), and electron density (ρ). The calculations have been performed for correlated wavefunctions using the CCSD and CASSCF methods. The F-O1 bond with non-bonding basins, V(F) and V(')(O1), belongs to the protocovalent type (η,Y(D)(σ)) and its total population ranges between 0.2 and 0.4e. The central N-O1 bond in the cis form is protocovalent (η, Y(D)(σ)) with two basins, V(N) and V(O1). The total population oscillates between 0.7 and 0.9e. In the trans isomer, topology of ELF depends on used method. At the CCSD level only one non-bonding basin, V(N), is observed (η). Its population is about 0.5e. According to the definition of a heteronuclear charge-shift (CS) bond, only N-O1 bond in trans-FONO belongs to the CS class. A relation between η- and ρ-topology and N-O1 bond length is discussed.

  3. The use of chemical shift temperature gradients to establish the paramagnetic susceptibility tensor orientation: Implication for structure determination/refinement in paramagnetic metalloproteins

    Energy Technology Data Exchange (ETDEWEB)

    Xia Zhicheng; Nguyen, Bao D.; La Mar, Gerd N. [University of California, Department of Chemistry (United States)

    2000-06-15

    The use of dipolar shifts as important constraints in refining molecular structure of paramagnetic metalloproteins by solution NMR is now well established. A crucial initial step in this procedure is the determination of the orientation of the anisotropic paramagnetic susceptibility tensor in the molecular frame which is generated interactively with the structure refinement. The use of dipolar shifts as constraints demands knowledge of the diamagnetic shift, which, however, is very often not directly and easily accessible. We demonstrate that temperature gradients of dipolar shifts can serve as alternative constraints for determining the orientation of the magnetic axes, thereby eliminating the need to estimate the diamagnetic shifts. This approach is tested on low-spin, ferric sperm whale cyanometmyoglobin by determining the orientation, anisotropies and anisotropy temperature gradients by the alternate routes of using dipolar shifts and dipolar shift gradients as constraints. The alternate routes ultimately lead to very similar orientation of the magnetic axes, magnetic anisotropies and magnetic anisotropy temperature gradients which, by inference, would lead to an equally valid description of the molecular structure. It is expected that the use of the dipolar shift temperature gradients, rather than the dipolar shifts directly, as constraints will provide an accurate shortcut in a solution structure determination of a paramagnetic metalloprotein.

  4. Tracking contributions to human body burden of environmental chemicals by correlating environmental measurements with biomarkers.

    Directory of Open Access Journals (Sweden)

    Hyeong-Moo Shin

    Full Text Available The work addresses current knowledge gaps regarding causes for correlations between environmental and biomarker measurements and explores the underappreciated role of variability in disaggregating exposure attributes that contribute to biomarker levels. Our simulation-based study considers variability in environmental and food measurements, the relative contribution of various exposure sources (indoors and food, and the biological half-life of a compound, on the resulting correlations between biomarker and environmental measurements. For two hypothetical compounds whose half-lives are on the order of days for one and years for the other, we generate synthetic daily environmental concentrations and food exposures with different day-to-day and population variability as well as different amounts of home- and food-based exposure. Assuming that the total intake results only from home-based exposure and food ingestion, we estimate time-dependent biomarker concentrations using a one-compartment pharmacokinetic model. Box plots of modeled R2 values indicate that although the R2 correlation between wipe and biological (e.g., serum measurements is within the same range for the two compounds, the relative contribution of the home exposure to the total exposure could differ by up to 20%, thus providing the relative indication of their contribution to body burden. The novel method introduced in this paper provides insights for evaluating scenarios or experiments where sample, exposure, and compound variability must be weighed in order to interpret associations between exposure data.

  5. High temperature conductance mapping for correlation of electrical properties with micron-sized chemical and microstructural features

    DEFF Research Database (Denmark)

    Hansen, Karin Vels; Norrman, Kion; Jacobsen, Torben

    2016-01-01

    High temperature AC conductance mapping is a scanning probe technique for resolving local electrical properties in microscopic areas. It is especially suited for detecting poorly conducting phases and for ionically conducting materials such as those used in solid oxide electrochemical cells....... Secondary silicate phases formed at the edge of lanthanum strontium manganite microelectrodes are used as an example for correlation of chemical, microstructural and electrical properties with a spatial resolution of 1–2 µm to demonstrate the technique. The measurements are performed in situ in a controlled...

  6. Correlation of the isosteric heat of adsorption of organic molecules over zeolites with equalized electronegativity and chemical hardness

    Indian Academy of Sciences (India)

    N V K Dutt; S J Kulkarni; Y V L Ravikumar; B S N Murthy

    2006-07-01

    Considering the direct correlation between charge transfer and heat of adsorption, we have equated the isosteric heat of adsorption () with Nalewajski's charge transfer equation involving equalized electronegativities and chemical hardness given in the literature. The equation is then tested and compared with the experimental heat of adsorption values of organic molecules over zeolites given in the literature with the average percentage deviation of 15.9. Other similar types of equations of charge transfer affinity are also tested. Various semi-empirical equations based on Barrer's approach of the determination of and neural network method have been proposed, tested and compared for the first time.

  7. Correlation between the Chemical and Genetic Relationships among Thymus saturejoides Genotypes Cultured under in vitro and in vivo Environments.

    Science.gov (United States)

    Nordine, Aicha; Udupa, Sripada M; Iraqi, Driss; Meksem, Khalid; Hmamouchi, Mohamed; ElMeskaoui, Abdelmalek

    2016-04-01

    In this study, the in vitro and in vivo essential oil (EO) composition and genetic variability in six micropropagated genotypes of Thymus saturejoides Coss., a Mediterranean medicinal and aromatic plant, were analyzed by GC/MS and randomly amplified polymorphic DNA (RAPD). Yield and composition of the EO varied between genotypes. Cluster analysis based on RAPD data and EO grouped the six genotypes in three groups in both culture conditions, thus showing considerable intraspecific genetic and chemical variations. Applying the Mantel test, the result showed a significant correlation between the two proximity matrices RAPD and EO obtained from in vitro genotypes, whereas this correlation was not observed when using the EO obtained from the in vivo genotypes.

  8. Correlations between Optical, Chemical and Physical Properties ofBiomass Burn Aerosols

    Energy Technology Data Exchange (ETDEWEB)

    Hopkins, Rebecca J.; Lewis, K.; Desyaterik, Yury; Wang, Z.; Tivanski, Alexei V.; Arnott, W.P.; Laskin, Alexander; Gilles, M.K.

    2008-01-29

    Aerosols generated from burning different plant fuels were characterized to determine relationships between chemical, optical and physical properties. Single scattering albedo ({omega}) and Angstrom absorption coefficients ({alpha}{sub ap}) were measured using a photoacoustic technique combined with a reciprocal nephelometer. Carbon-to-oxygen atomic ratios, sp{sup 2} hybridization, elemental composition and morphology of individual particles were measured using scanning transmission X-ray microscopy coupled with near-edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS) and scanning electron microscopy with energy dispersion of X-rays (SEM/EDX). Particles were grouped into three categories based on sp2 hybridization and chemical composition. Measured {omega} (0.4-1.0 at 405 nm) and {alpha}{sub ap} (1.0-3.5) values displayed a fuel dependence. The category with sp{sup 2} hybridization >80% had values of {omega} (<0.5) and {alpha}{sub ap} ({approx}1.25) characteristic of light absorbing soot. Other categories with lower sp2 hybridization (20 to 60%) exhibited higher {omega} (>0.8) and {alpha}{sub ap} (1.0 to 3.5) values, indicating increased absorption spectral selectivity.

  9. Origin of the chemical shift in X-ray absorption near-edge spectroscopy at the Mn K-Edge in manganese oxide compounds

    NARCIS (Netherlands)

    de Vries, AH; Hozoi, L; Broer, R; Broer-Braam, H.B.

    2003-01-01

    The absorption edge in Mn K-edge X-ray absorption spectra of manganese oxide compounds shows a shift of several electronvolts in going from MnO through LaMnO3 to CaMnO3. On the other hand, in X-ray photoelectron spectra much smaller shifts are observed. To identify the mechanisms that cause the obse

  10. (1) H NMR Spectra. Part 28: Proton chemical shifts and couplings in three-membered rings. A ring current model for cyclopropane and a novel dihedral angle dependence for (3) J(HH) couplings involving the epoxy proton.

    Science.gov (United States)

    Abraham, Raymond J; Leonard, Paul; Tormena, Cláudio F

    2012-04-01

    The (1) H chemical shifts of selected three-membered ring compounds in CDCl(3) solvent were obtained. This allowed the determination of the substituent chemical shifts of the substituents in the three-membered rings and the long-range effect of these rings on the distant protons. The substituent chemical shifts of common substituents in the cyclopropane ring differ considerably from the same substituents in acyclic fragments and in cyclohexane and were modelled in terms of a three-bond (γ)-effect. For long-range protons (more than three bonds removed), the substituent effects of the cyclopropane ring were analysed in terms of the cyclopropane magnetic anisotropy and steric effect. The cyclopropane magnetic anisotropy (ring current) shift was modelled by (a) a single equivalent dipole perpendicular to and at the centre of the cyclopropane ring and (b) by three identical equivalent dipoles perpendicular to the ring placed at each carbon atom. Model (b) gave a more accurate description of the (1) H chemical shifts and was the selected model. After parameterization, the overall root mean square error for the dataset of 289 entries was 0.068 ppm. The anisotropic effects are significant for the cyclopropane protons (ca 1 ppm) but decrease rapidly with distance. The heterocyclic rings of oxirane, thiirane and aziridine do not possess a ring current. (3) J(HH) couplings of the epoxy ring proton with side-chain protons were obtained and shown to be dependent on both the H-C-C-H and H-C-C-O orientations. Both density functional theory calculations and a simple Karplus-type equation gave general agreement with the observed couplings (root mean square error 0.5 Hz over a 10-Hz range).

  11. Surface magnetism Correlation of structural, electronic and chemical properties with magnetic behavior

    CERN Document Server

    Getzlaff, Mathias

    2010-01-01

    This volume reviews on selected aspects related to surface magnetism, a field of extraordinary interest during the last decade. The special emphasis is set to the correlation of structural, electronic and magnetic properties in rare earth metal systems and ferromagnetic transition metals. This is made possible by the combination of electron emission techniques (spin polarized photoelectron spectroscopy, magnetic dichroism in photoemission and spin polarized metastable deexcitation spectroscopy) and local probes with high lateral resolution down to the atomic scale (spin polarized scanning tunneling microscopy / spectroscopy).

  12. X-ray texture analysis of paper coating pigments and the correlation with chemical composition analysis

    Science.gov (United States)

    Roine, J.; Tenho, M.; Murtomaa, M.; Lehto, V.-P.; Kansanaho, R.

    2007-10-01

    The present research experiments the applicability of x-ray texture analysis in investigating the properties of paper coatings. The preferred orientations of kaolin, talc, ground calcium carbonate, and precipitated calcium carbonate particles used in four different paper coatings were determined qualitatively based on the measured crystal orientation data. The extent of the orientation, namely, the degree of the texture of each pigment, was characterized quantitatively using a single parameter. As a result, the effect of paper calendering is clearly seen as an increase on the degree of texture of the coating pigments. The effect of calendering on the preferred orientation of kaolin was also evident in an independent energy dispersive spectrometer analysis on micrometer scale and an electron spectroscopy for chemical analysis on nanometer scale. Thus, the present work proves x-ray texture analysis to be a potential research tool for characterizing the properties of paper coating layers.

  13. Volatile terpenes from actinomycetes: a biosynthetic study correlating chemical analyses to genome data.

    Science.gov (United States)

    Rabe, Patrick; Citron, Christian A; Dickschat, Jeroen S

    2013-11-25

    The volatile terpenes of 24 actinomycetes whose genomes have been sequenced (or are currently being sequenced) were collected by use of a closed-loop stripping apparatus and identified by GC/MS. The analytical data were compared against a phylogenetic analysis of all 192 currently available sequences of bacterial terpene cyclases (excluding geosmin and 2-methylisoborneol synthases). In addition to the several groups of terpenes with known biosynthetic origin, selinadienes were identified as a large group of biosynthetically related sesquiterpenes that are produced by several streptomycetes. The detection of a large number of previously unrecognised side products of known terpene cyclases proved to be particularly important for an in depth understanding of biosynthetic pathways to known terpenes in actinomycetes. Interpretation of the chemical analytical data in the context of the phylogenetic tree of bacterial terpene cyclases pointed to the function of three new enzymes: (E)-β-caryophyllene synthase, selina-3,7(11)-diene synthase and aristolochene synthase.

  14. Utility of chemical-shift MR imaging in detecting small amounts of fat in extrahepatic abdominal tumors; Utilidad de la tecnica de desplazamiento quimico den RM para la deteccion de pequenas cantidades de grasa en tumores abdominales extrahepaticos

    Energy Technology Data Exchange (ETDEWEB)

    Martin, J.; Falco, J.; Puig, J.; Donoso, L. [Unidad de Diagnostico por Imagen de Alta Tecnologia (UDIAT). Sabadell (Spain)

    1999-07-01

    To determine the utility of the chemical shift technique in magnetic resonance imaging (MRI) to confirm small amounts of fat in extrahepatic intraabdominal tumours. 7 extrahepatic abdominal tumours that are suspected to have fat as seen in the axial computed tomography (TC) are analysed retrospectively. In order to confirm the fat content, the chemical displacement technique with gradient echo sequences (GE) in phase (P) and in opposite phase (OP) was used with MRI 1 T equipment. The tumours corresponded to renal angiomyolipoma (AML) (n=4), intraperitoneal liposarcoma (n=1), retroperitoneal liposarcoma (n=1) and intraabdominal extramedular hematopoiesis (n=1). To confirm the existence of fat in the tumours, we used a quantitative percentage variation parameter of the intensity of the signals (VIS) between the images in P and OP, according to the formula: IS{sub (}p)-IS({sub o}p)x100/IS{sub (}op), where IS is the intensity of the signal. The chemical shift technique showed fat in the seven tumours. Upon visual inspection, all the tumoral areas that were suspected to have fat showed a notable difference in the signal intensity, being hypointense in OP and hyperintense in P. In these areas the average VIS percentage was 170% while in the rest of the tumour the average VIS percentage was 3%. The chemical shift technique with RG sequences can be easily used in MRI equipment and allows us to confirm if a specific abdominal tumour has fat, even if there is only a small quantity. (Author) 13 refs.

  15. Correlation of chemical compositions of cassava varieties to their resistance to Prostephanus truncatus Horn (Coleoptera: Bostrichidae).

    Science.gov (United States)

    Osipitan, Adebola A; Sangowusi, Victoria T; Lawal, Omoniyi I; Popoola, Kehinde O

    2015-01-01

    The preference of cassava as a major host by Prostephanus truncatus Horn is a major constraint to ample production of cassava, Manihot esculenta Crantz and storage. This study analyzed the nutritional and secondary metabolite compositions in 15 cassava varieties, evaluated levels of damage and reproduction by P. truncatus, and assessed their resistance to attack. One hundred grams of dried cassava chips in 250-ml Kilner jars were infested with 10 adult larger grain borerof 0-10 days old and held for 3 months. The nutritional and secondary metabolites compositions of the dry cassava chips were determined using the method of Association of Analytical Chemists . Chip perforation rates in the cassava varieties ranged from 17.7 to 71.6%. The weight of cassava powder varied by about threefold. The final number of larger grain borer in the cassava varieties varied by about sixfold with 63 in 01/0040 and 379 in 01/1368. Hydrocyanic acid content content varied by over 10-fold and correlated negatively with number of larger grain borer. Flavonoid content varied by ∼10%. Tannins and saponin content of the cassava negatively correlated with number of adult P. truncatus. The cassava varieties 95/0166, 92/0326, 01/0040, 05/0024, and 34 91934 had selection index 0.8 were classified as susceptible. The resistance to high damage in the resistant varieties was conferred by secondary metabolites such as tannins, saponins, alkaloids, and hydrocyanic acid content. The genetic variation in cassava varieties could be explored to breed resistant cassava varieties for use in larger grain borer-endemic areas.

  16. CHEMICALS

    CERN Multimedia

    Medical Service

    2002-01-01

    It is reminded that all persons who use chemicals must inform CERN's Chemistry Service (TIS-GS-GC) and the CERN Medical Service (TIS-ME). Information concerning their toxicity or other hazards as well as the necessary individual and collective protection measures will be provided by these two services. Users must be in possession of a material safety data sheet (MSDS) for each chemical used. These can be obtained by one of several means : the manufacturer of the chemical (legally obliged to supply an MSDS for each chemical delivered) ; CERN's Chemistry Service of the General Safety Group of TIS ; for chemicals and gases available in the CERN Stores the MSDS has been made available via EDH either in pdf format or else via a link to the supplier's web site. Training courses in chemical safety are available for registration via HR-TD. CERN Medical Service : TIS-ME :73186 or service.medical@cern.ch Chemistry Service : TIS-GS-GC : 78546

  17. Soymilk plain beverages: correlation between acceptability and physical and chemical characteristics

    Directory of Open Access Journals (Sweden)

    Marcela Moreira Terhaag

    2013-06-01

    Full Text Available The objective of the research was to relate the physical and chemical characteristics of soymilk plain beverages to its sensory acceptance. Five commercial products and a new product formulated based on the less accepted sample were used. The overall acceptance was evaluated by 102 assessors using a 10-point hybrid hedonic scale. The hedonic scores ranged from 3.8 (sample E to 7.0 (A. Most assessors (55% preferred sample A, which was viscous (26.6 cp, dark (L* = 77.7, and slightly acidic (pH = 6.6. Sample C, which had lower solid content and higher acidity, was preferred by 29% of the assessors. These two beverages showed the greatest commercial potential of the products analyzed. The least-accepted sample (E, preferred by 8% of the assessors, had a lighter color (L* = 96.8, lower viscosity (13.5 cp, higher lipid content (2.2 g/100 g, and less protein (1.68 g/100 g than the other products evaluated. A reformulation of the least preferred product (E with the addition of maltodextrin and also vanilla and milk flavors increased its acceptance, yielding an average score of 7.2. Overall, it was observed that a soymilk plain beverage with higher viscosity, darker color, and higher protein content best meets consumer expectations.

  18. Correlation Study on Sweetness of Amino Acid with Different Configurations and Quantum Chemical Parameters

    Institute of Scientific and Technical Information of China (English)

    LI Jun-Ling; GU Jun; QIU Guang-Min

    2006-01-01

    Quantum chemical parameters of 10 amino acids with D- and L-configurations were firstly calculated with semi-empirical AM1 method. Furthermore, the relationship between mole- cular structures of D-, L-amino acids and their sweetness were observed. The results show that upon different configurations of amino acids, the sweetness is relative with their formation heat, dipole moment, energy gap of frontier orbital and other parameters. The formation heats of the same amino acids possessing D- and L-configurations are different except glycine. The algebraic value of D- amino acid is generally larger than that of corresponding L-configuration with only one except of tyrosine. The dipole moment of D-amino acid is generally larger than that of corresponding L-amino acid except tyrosine and lysine. The lowest unoccupied orbital energy (ELUMO) of D-amino acid is higher than that of corresponding L-configuration except phenylalanine. △E of D-amino acid is larger than that of L-amino acid except histidine, phenylalanine and lysine. The larger gap will have advantage for its matching with frontier orbital energy of human protein acceptor, which strengthens the interaction between D-amino acid and sweet taste acceptor. Besides, the changing rules of these parameters are generally identical.

  19. Correlation between somatic cell count and chemical composition of cooled raw milk in properties of Rio Grande do Norte, Brazil

    Directory of Open Access Journals (Sweden)

    Adriano Henrique do Nascimento Rangel

    2014-06-01

    Full Text Available Due to the damage caused by subclinical mastitis in loss of production and quality of milk, the present study aimed to verify the correlation between somatic cell count (SCC and the chemical composition of cooled raw milk collected in the Agreste region of Rio Grande do Norte, Brazil, in drought and rain seasons. Samples were collected in seven dairy farms during morning time, between January 2010 and March 2012, and sent to the Brazilian et of Milk Quality Laboratory (ESALQ/USP. The contents of protein, fat, lactose, casein, total solids, nonfat dry extract and urea nitrogen, besides of SCC and total bacterial count were performed. Data were submitted to analysis of variance, correlation analysis and comparison of means by Tuckey test , 5%. The average SCC was 604,000 cells/mL and had significant variation in the dry period (558 000 cells/mL and rainy (650 000 cells/mL. The SCC was positively correlated with fat and total solids but negatively with the lactose cow’s milk of bulk tank, regardless of the season in the Agreste of Rio Grande do Norte.

  20. Determination of pKa values of tenoxicam from 1H NMR chemical shifts and of oxicams from electrophoretic mobilities (CZE) with the aid of programs SQUAD and HYPNMR.

    Science.gov (United States)

    Rodríguez-Barrientos, Damaris; Rojas-Hernández, Alberto; Gutiérrez, Atilano; Moya-Hernández, Rosario; Gómez-Balderas, Rodolfo; Ramírez-Silva, María Teresa

    2009-12-15

    In this work it is explained, by the first time, the application of programs SQUAD and HYPNMR to refine equilibrium constant values through the fit of electrophoretic mobilities determined by capillary zone electrophoresis experiments, due to the mathematical isomorphism of UV-vis absorptivity coefficients, NMR chemical shifts and electrophoretic mobilities as a function of pH. Then, the pK(a) values of tenoxicam in H(2)O/DMSO 1:4 (v/v) have been obtained from (1)H NMR chemical shifts, as well as of oxicams in aqueous solution from electrophoretic mobilities determined by CZE, at 25 degrees C. These values are in very good agreement with those reported by spectrophotometric and potentiometric measurements.

  1. Lanthanide ion (III) complexes of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraaminophosphonate for dual biosensing of pH with chemical exchange saturation transfer (CEST) and biosensor imaging of redundant deviation in shifts (BIRDS).

    Science.gov (United States)

    Huang, Yuegao; Coman, Daniel; Ali, Meser M; Hyder, Fahmeed

    2015-01-01

    Relaxivity-based magnetic resonance of phosphonated ligands chelated with gadolinium (Gd(3+)) shows promise for pH imaging. However instead of monitoring the paramagnetic effect of lanthanide complexes on the relaxivity of water protons, biosensor (or molecular) imaging with magnetic resonance is also possible by detecting either the nonexchangeable or the exchangeable protons on the lanthanide complexes themselves. The nonexchangeable protons (e.g. -CHx, where 3 ≥ x ≥ 1) are detected using a three-dimensional chemical shift imaging method called biosensor imaging of redundant deviation in shifts (BIRDS), whereas the exchangeable protons (e.g. -OH or -NHy , where 2 ≥ y ≥ 1) are measured with chemical exchange saturation transfer (CEST) contrast. Here we tested the feasibility of BIRDS and CEST for pH imaging of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraaminophosphonate (DOTA-4AmP(8-)) chelated with thulium (Tm(3+) ) and ytterbium (Yb(3+)). BIRDS and CEST experiments show that both complexes are responsive to pH and temperature changes. Higher pH and temperature sensitivities are obtained with BIRDS for either complex when using the chemical shift difference between two proton resonances vs using the chemical shift of a single proton resonance, thereby eliminating the need to use water resonance as reference. While CEST contrast for both agents is linearly dependent on pH within a relatively large range (i.e. 6.3-7.9), much stronger CEST contrast is obtained with YbDOTA-4AmP(5-) than with TmDOTA-4AmP(5-). In addition, we demonstrate the prospect of using BIRDS to calibrate CEST as new platform for quantitative pH imaging.

  2. Bacterial genomes lacking long-range correlations may not be modeled by low-order Markov chains: the role of mixing statistics and frame shift of neighboring genes.

    Science.gov (United States)

    Cocho, Germinal; Miramontes, Pedro; Mansilla, Ricardo; Li, Wentian

    2014-12-01

    We examine the relationship between exponential correlation functions and Markov models in a bacterial genome in detail. Despite the well known fact that Markov models generate sequences with correlation function that decays exponentially, simply constructed Markov models based on nearest-neighbor dimer (first-order), trimer (second-order), up to hexamer (fifth-order), and treating the DNA sequence as being homogeneous all fail to predict the value of exponential decay rate. Even reading-frame-specific Markov models (both first- and fifth-order) could not explain the fact that the exponential decay is very slow. Starting with the in-phase coding-DNA-sequence (CDS), we investigated correlation within a fixed-codon-position subsequence, and in artificially constructed sequences by packing CDSs with out-of-phase spacers, as well as altering CDS length distribution by imposing an upper limit. From these targeted analyses, we conclude that the correlation in the bacterial genomic sequence is mainly due to a mixing of heterogeneous statistics at different codon positions, and the decay of correlation is due to the possible out-of-phase between neighboring CDSs. There are also small contributions to the correlation from bases at the same codon position, as well as by non-coding sequences. These show that the seemingly simple exponential correlation functions in bacterial genome hide a complexity in correlation structure which is not suitable for a modeling by Markov chain in a homogeneous sequence. Other results include: use of the (absolute value) second largest eigenvalue to represent the 16 correlation functions and the prediction of a 10-11 base periodicity from the hexamer frequencies.

  3. Power Shift

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ "We are entering a new era of world history: the end of Western domination and the arrival of the Asian century. The question is: will Washington wake up to this reality?" This is the central premise of Kishore Mahbubani's provocative new book The New Asian Hemisphere: The Irresistible Shift of Global Power to the East.

  4. Correlation between topological band character and chemical bonding in a Bi14Rh3I9-based family of insulators

    Science.gov (United States)

    Rasche, Bertold; Isaeva, Anna; Ruck, Michael; Koepernik, Klaus; Richter, Manuel; van den Brink, Jeroen

    2016-02-01

    Recently the presence of topologically protected edge-states in Bi14Rh3I9 was confirmed by scanning tunnelling microscopy consolidating this compound as a weak 3D topological insulator (TI). Here, we present a density-functional-theory-based study on a family of TIs derived from the Bi14Rh3I9 parent structure via substitution of Ru, Pd, Os, Ir and Pt for Rh. Comparative analysis of the band-structures throughout the entire series is done by means of a unified minimalistic tight-binding model that evinces strong similarity between the quantum-spin-Hall (QSH) layer in Bi14Rh3I9 and graphene in terms of -molecular orbitals. Topologically non-trivial energy gaps are found for the Ir-, Rh-, Pt- and Pd-based systems, whereas the Os- and Ru-systems remain trivial. Furthermore, the energy position of the metal -band centre is identified as the parameter which governs the evolution of the topological character of the band structure through the whole family of TIs. The -band position is shown to correlate with the chemical bonding within the QSH layers, thus revealing how the chemical nature of the constituents affects the topological band character.

  5. CHEMICAL DETERMINATION OF HEAVY METALS IN PB AND ZN CONCENTRATES OF TREPÇA (KOSOVO AND CORRELATIONS COEFFI CIENTS STUDY BETWEEN CHEMICAL DATA

    Directory of Open Access Journals (Sweden)

    Fatbardh Gashi

    2017-03-01

    Full Text Available Kosovo ore deposits are located in the Trepça belt which extends for over 80 km. The concentrate produced by the flotation process of the Trepça metallurgical corporation contains a considerable quantity of valuable metals, such as Pb, Zn, Fe and minor accompanying metals such as Cd, Cu, As, Sb, Bi, Ag, Au, etc. The subject of this work was to assess the concentration of major and minor metals in lead and zinc concentrates of Trepça and to study the correlation coefficients between metals. Chemical determination of concentrates was performed by using atomic absorption spectroscopy (AAS. In the content on lead concentrate samples, the following were found: Pb>Fe>Zn> Ag> As>Sb>Cd. In the content of zinc concentrate, the following were found: Zn>Fe>Pb>Ag>As>Cd. The program “Statistica ver. 6.0” has been used for calculations of basic statistical parameters, relationships between data and cluster analysis of R-mode. R-mode cluster analysis on lead concentrate samples showed that Pb has the closest linkages with Fe and they form one branch of the dendogram. On the zinc concentrate samples, Zn has the closest linkages with Fe and they form one branch of the dendogram.

  6. Prediction of (195) Pt NMR chemical shifts of dissolution products of H2 [Pt(OH)6 ] in nitric acid solutions by DFT methods: how important are the counter-ion effects?

    Science.gov (United States)

    Tsipis, Athanassios C; Karapetsas, Ioannis N

    2016-08-01

    (195) Pt NMR chemical shifts of octahedral Pt(IV) complexes with general formula [Pt(NO3 )n (OH)6 - n ](2-) , [Pt(NO3 )n (OH2 )6 - n ](4 - n) (n = 1-6), and [Pt(NO3 )6 - n  - m (OH)m (OH2 )n ](-2 + n - m) formed by dissolution of platinic acid, H2 [Pt(OH)6 ], in aqueous nitric acid solutions are calculated employing density functional theory methods. Particularly, the gauge-including atomic orbitals (GIAO)-PBE0/segmented all-electron relativistically contracted-zeroth-order regular approximation (SARC-ZORA)(Pt) ∪ 6-31G(d,p)(E)/Polarizable Continuum Model computational protocol performs the best. Excellent second-order polynomial plots of δcalcd ((195) Pt) versus δexptl ((195) Pt) chemical shifts and δcalcd ((195) Pt) versus the natural atomic charge QPt are obtained. Despite of neglecting relativistic and spin orbit effects the good agreement of the calculated δ (195) Pt chemical shifts with experimental values is probably because of the fact that the contribution of relativistic and spin orbit effects to computed σ(iso) (195) Pt magnetic shielding of Pt(IV) coordination compounds is effectively cancelled in the computed δ (195) Pt chemical shifts, because the relativistic corrections are expected to be similar in the complexes and the proper reference standard used. To probe the counter-ion effects on the (195) Pt NMR chemical shifts of the anionic [Pt(NO3 )n (OH)6 - n ](2-) and cationic [Pt(NO3 )n (OH2 )6 - n ](4 - n) (n = 0-3) complexes we calculated the (195) Pt NMR chemical shifts of the neutral (PyH)2 [Pt(NO3 )n (OH)6 - n ] (n = 1-6; PyH = pyridinium cation, C5 H5 NH(+) ) and [Pt(NO3 )n (H2 O)6 - n ](NO3 )4 - n (n = 0-3) complexes. Counter-anion effects are very important for the accurate prediction of the (195) Pt NMR chemical shifts of the cationic [Pt(NO3 )n (OH2 )6 - n ](4 - n) complexes, while counter-cation effects are less important for the anionic [Pt(NO3 )n (OH)6

  7. DOPING AND BOND LENGTH CONTRIBUTIONS TO Mn K-EDGE SHIFT IN La1-xSrxMnO3 AND THEIR CORRELATION WITH ELECTRICAL TRANSPORT BEHAVIOUR.

    Energy Technology Data Exchange (ETDEWEB)

    PANDEY,S.K.; KHALID,S.; BINDU, R.; KUMAR, A.; PIMPALE, A.V.

    2006-12-04

    The experimental Mn K-edge x-ray absorption spectra of La{sub 1-x}Sr{sub x}MnO{sub 3}, x = 0 - 0.7 are compared with the band structure calculations using spin polarized density functional theory. It is explicitly shown that there is a correspondence between the inflection point on the absorption edge and the center of gravity of the unoccupied Mn 4p-band. This correspondence has been used to separate the doping and size contributions to edge shift due to variation in number of electrons in valence band and Mn-O bond lengths, respectively when Sr is doped into LaMnO{sub 3}. Such separation is helpful to find the localization behavior of charge carriers and to understand the observed transport properties and type of charge carrier participating in the conduction process in these compounds.

  8. Fluid Shifts

    Science.gov (United States)

    Stenger, M. B.; Hargens, A. R.; Dulchavsky, S. A.; Arbeille, P.; Danielson, R. W.; Ebert, D. J.; Garcia, K. M.; Johnston, S. L.; Laurie, S. S.; Lee, S. M. C.; Liu, J.; Macias, B.; Martin, D. S.; Minkoff, L.; Ploutz-Snyder, R.; Ribeiro, L. C.; Sargsyan, A.; Smith, S. M.

    2017-01-01

    Introduction. NASA's Human Research Program is focused on addressing health risks associated with long-duration missions on the International Space Station (ISS) and future exploration-class missions beyond low Earth orbit. Visual acuity changes observed after short-duration missions were largely transient, but now more than 50 percent of ISS astronauts have experienced more profound, chronic changes with objective structural findings such as optic disc edema, globe flattening and choroidal folds. These structural and functional changes are referred to as the visual impairment and intracranial pressure (VIIP) syndrome. Development of VIIP symptoms may be related to elevated intracranial pressure (ICP) secondary to spaceflight-induced cephalad fluid shifts, but this hypothesis has not been tested. The purpose of this study is to characterize fluid distribution and compartmentalization associated with long-duration spaceflight and to determine if a relation exists with vision changes and other elements of the VIIP syndrome. We also seek to determine whether the magnitude of fluid shifts during spaceflight, as well as any VIIP-related effects of those shifts, are predicted by the crewmember's pre-flight status and responses to acute hemodynamic manipulations, specifically posture changes and lower body negative pressure. Methods. We will examine a variety of physiologic variables in 10 long-duration ISS crewmembers using the test conditions and timeline presented in the figure below. Measures include: (1) fluid compartmentalization (total body water by D2O, extracellular fluid by NaBr, intracellular fluid by calculation, plasma volume by CO rebreathe, interstitial fluid by calculation); (2) forehead/eyelids, tibia, and calcaneus tissue thickness (by ultrasound); (3) vascular dimensions by ultrasound (jugular veins, cerebral and carotid arteries, vertebral arteries and veins, portal vein); (4) vascular dynamics by MRI (head/neck blood flow, cerebrospinal fluid

  9. Helichrysum gymnocephalum Essential Oil: Chemical Composition and Cytotoxic, Antimalarial and Antioxidant Activities, Attribution of the Activity Origin by Correlations

    Directory of Open Access Journals (Sweden)

    François Couderc

    2011-09-01

    Full Text Available Helichrysum gymnocephalum essential oil (EO was prepared by hydrodistillation of its leaves and characterized by GC-MS and quantified by GC-FID. Twenty three compounds were identified. 1,8-Cineole (47.4%, bicyclosesquiphellandrene (5.6%, γ-curcumene (5.6%, α-amorphene (5.1% and bicyclogermacrene (5% were the main components. Our results confirmed the important chemical variability of H. gymnocephalum. The essential oil was tested in vitro for cytotoxic (on human breast cancer cells MCF-7, antimalarial (Plasmodium falciparum: FcB1-Columbia strain, chloroquine-resistant and antioxidant (ABTS and DPPH assays activities. H. gymnocephalum EO was found to be active against MCF-7 cells, with an IC50 of 16 ± 2 mg/L. The essential oil was active against P. falciparum (IC50 = 25 ± 1 mg/L. However, the essential oil exhibited a poor antioxidant activity in the DPPH (IC50 value > 1,000 mg/L and ABTS (IC50 value = 1,487.67 ± 47.70 mg/L assays. We have reviewed the existing results on the anticancer activity of essential oils on MCF-7 cell line and on their antiplasmodial activity against the P. falciparum. The aim was to establish correlations between the identified compounds and their biological activities (antiplasmodial and anticancer. β-Selinene (R² = 0.76, α-terpinolene (R² = 0.88 and aromadendrene (R² = 0.90 presented a higher relationship with the anti-cancer activity. However, only calamenene (R² = 0.70 showed a significant correlation for the antiplasmodial activity.

  10. Site-specific protein backbone and side-chain NMR chemical shift and relaxation analysis of human vinexin SH3 domain using a genetically encoded {sup 15}N/{sup 19}F-labeled unnatural amino acid

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Pan [National Laboratory for Physical Science at Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China); School of Life Science, University of Science and Technology of China, Hefei, Anhui 230026 (China); Xi, Zhaoyong; Wang, Hu [School of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026 (China); Shi, Chaowei [National Laboratory for Physical Science at Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China); School of Life Science, University of Science and Technology of China, Hefei, Anhui 230026 (China); Xiong, Ying, E-mail: yxiong73@ustc.edu.cn [School of Life Science, University of Science and Technology of China, Hefei, Anhui 230026 (China); Tian, Changlin, E-mail: cltian@ustc.edu.cn [National Laboratory for Physical Science at Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2010-11-19

    Research highlights: {yields} Chemical synthesis of {sup 15}N/{sup 19}F-trifluomethyl phenylalanine. {yields} Site-specific incorporation of {sup 15}N/{sup 19}F-trifluomethyl phenylalanine to SH3. {yields} Site-specific backbone and side chain chemical shift and relaxation analysis. {yields} Different internal motions at different sites of SH3 domain upon ligand binding. -- Abstract: SH3 is a ubiquitous domain mediating protein-protein interactions. Recent solution NMR structural studies have shown that a proline-rich peptide is capable of binding to the human vinexin SH3 domain. Here, an orthogonal amber tRNA/tRNA synthetase pair for {sup 15}N/{sup 19}F-trifluoromethyl-phenylalanine ({sup 15}N/{sup 19}F-tfmF) has been applied to achieve site-specific labeling of SH3 at three different sites. One-dimensional solution NMR spectra of backbone amide ({sup 15}N){sup 1}H and side-chain {sup 19}F were obtained for SH3 with three different site-specific labels. Site-specific backbone amide ({sup 15}N){sup 1}H and side-chain {sup 19}F chemical shift and relaxation analysis of SH3 in the absence or presence of a peptide ligand demonstrated different internal motions upon ligand binding at the three different sites. This site-specific NMR analysis might be very useful for studying large-sized proteins or protein complexes.

  11. Plakilactones G and H from a marine sponge. Stereochemical determination of highly flexible systems by quantitative NMR-derived interproton distances combined with quantum mechanical calculations of 13C chemical shifts

    Directory of Open Access Journals (Sweden)

    Simone Di Micco

    2013-12-01

    Full Text Available In this paper the stereostructural investigation of two new oxygenated polyketides, plakilactones G and H, isolated from the marine sponge Plakinastrella mamillaris collected at Fiji Islands, is reported. The stereostructural studies began on plakilactone H by applying an integrated approach of the NOE-based protocol and quantum mechanical calculations of 13C chemical shifts. In particular, plakilactone H was used as a template to extend the application of NMR-derived interproton distances to a highly flexible molecular system with simultaneous assignment of four non-contiguous stereocenters. Chemical derivatization and quantum mechanical calculations of 13C on plakilactone G along with a plausible biogenetic interconversion between plakilactone G and plakilactone H allowed us to determine the absolute configuration in this two new oxygenated polyketides.

  12. Evaluation of Beef by Electronic Tongue System TS-5000Z: Flavor Assessment, Recognition and Chemical Compositions According to Its Correlation with Flavor.

    Directory of Open Access Journals (Sweden)

    Xinzhuang Zhang

    Full Text Available The aim of this study was to assess the ability of electronic tongue system TS-5000Z to evaluate meat quality based on flavor assessment, recognition and correlation with the meat chemical composition. Meat was sampled from eighteen beef cattle including 6 Wagyu breed cattle, 6 Angus breed cattle and 6 Simmental breed cattle. Chemical composition including dry matter, crude protein, fat, ash, cholesterol and taurine and flavor of the meat were measured. The results showed that different breed cattle had different chemical compositions and flavor, which contains sourness, umami, saltiness, bitterness, astringency, aftertaste from astringency, aftertaste from bitterness and aftertaste from umami, respectively. A principal component analysis (PCA showed an easily visible separation between different breeds of cattle and indicated that TS-5000Z made a rapid identification of different breeds of cattle. In addition, TS-5000Z seemed to be used to predict the chemical composition according to its correlation with the flavor. In conclusion, TS-5000Z would be used as a rapid analytical tool to evaluate the beef quality both qualitatively and quantitatively, based on flavor assessment, recognition and chemical composition according to its correlation with flavor.

  13. 氢键复合物中键长变化与振动频率移动相关性重访%Correlation between Bond-Length Change and Vibrational Frequency Shift in Hydrogen-Bonded Complexes Revisited

    Institute of Scientific and Technical Information of China (English)

    张愚; 马宁; 王伟周

    2012-01-01

    X—H…Y(Y为电子供体)型氢键形成时,X-H键长伸长或缩短与相应的X-H伸缩振动频率红移或蓝移存在较强的相关性,这也是氢键光谱检测和研究的基础.但是,最近的理论研究却推翻了这一观点,认为X-H键长变化和相应的X-H伸缩振动频率移动在有些氢键体系中并不存在相关性(McDowell,S.A.C.;Buckingham,A.D.J.Am.Chem.Soc.2005,127,15515.).本文中,我们采用更为可信的计算方法,对这一问题进行再研究.结果表明是错误的计算方法导致了McDowell和Buckingham得出错误的结论.在McDowell和Buckingham所研究的氢键体系中,X-H键长变化和相应的X-H伸缩振动频率移动仍存在较强的相关性.%The correlation between the X-H bond-length change and the corresponding X-H stretching frequency shift upon X - H … Y (Y is an electron donor) hydrogen bond formation is the basis for the spectroscopic detection and investigation of the hydrogen bond.However,this view has been questioned in a recent report,suggesting that the widely accepted correlation between the bond-length change and the frequency shift in hydrogen-bonded complexes is unreliable (McDowell,S.A.C.; Buckingham,A.D.J.Am.Chem.Soc.2005,127,15515.).In this work,several robust computational methods have been used to investigate this issue.The results clearly show that a computational artifact leads to the conclusion incorrectly reported by McDowell and Buckingham and that the correlation between the X- H bond-length change and the corresponding X- H stretching frequency shift is still very good in the hydrogen-bonded complexes studied.

  14. Organic compounds as corrosion inhibitors for mild steel in acidic media: correlation between inhibition efficiency and chemical structure

    Energy Technology Data Exchange (ETDEWEB)

    Elias, Elizandra C.S.; Chrisman, Erika C.A.N. [Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ (Brazil). Escola de Quimica

    2009-12-19

    The use of inhibitors for mild steels corrosion control which are in contact with aggressive environment is an accepted practice in acid treatment of oil-wells. Organic compounds have been studied to evaluate their corrosion inhibition potential. Film-forming corrosion inhibitors, commonly used to protect oil-field equipment, can be absorbed on the steel surface to give structurally ordered layers. Therefore, the electrons should act as an important role for this adsorption. Studies reveal that organic compounds show significant inhibition efficiency. For this purpose, their molecules should contain N, O and S heteroatoms in various functional groups, long hydrocarbon linear or branched radical and anion and cation active components. However, most of these compounds are not only expensive but also toxic to living beings. According to the 'Green Chemistry' rules, corrosion inhibitors based on organic compounds should be cheap, with low toxicity and have high inhibition efficiency. In this study, the effects of some organic compounds with different groups such as amide, ether, phenyldiamine, anime and aminophenol on the corrosion behavior of mild steel in acidic media have been investigated. The experimental data were obtained by gravimetric measurements. The results show that these compounds reveal a promising corrosion inhibition where phenyldiamine is the most efficient. The effect of molecular structure on the corrosion inhibition efficiency was investigated by semi-empirical quantum chemical calculations. The electronic properties such as highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO) energy levels, and LUMO-HOMO energy gap orbital density were calculated. The relations between the inhibition efficiency and some quantum parameters are discussed and correlations are proposed. The highest values for the HOMO densities were found in the vicinity nitrogen atom, indicating that it is the most probable adsorption center

  15. Spin-orbit ZORA and four-component Dirac-Coulomb estimation of relativistic corrections to isotropic nuclear shieldings and chemical shifts of noble gas dimers

    DEFF Research Database (Denmark)

    Jankowska, Marzena; Kupka, Teobald; Stobiński, Leszek

    2016-01-01

    Hartree-Fock and density functional theory with the hybrid B3LYP and general gradient KT2 exchange-correlation functionals were used for non-relativistic and relativistic nuclear magnetic shielding calculations of helium, neon, argon, krypton and xenon dimers and free atoms. Relativistic...

  16. Influence of Chemical Effect on the Kβ/Kα Intensity Ratios and Kβ Energy Shift of Co, Ni, Cu, and Zn Complexes

    Institute of Scientific and Technical Information of China (English)

    G. Apaydma, V. Ayhkg; Z. Biyiklioglu; E. Tirasoglu; H. Kantekin

    2008-01-01

    Chemical effects on the Kβ/Kα intensity ratios and ΔE energy differences for Co, Ni, Cu, and Zn complexes were investigated. The samples were excited by 59.5 keV γ-rays from a 241 Am annular radioactive source. K X-rays emitted by samples were counted by an Ultra-LEGe detector with a resolution of 150 eV at 5.9 keV. We observed the effects of different ligands on the Kβ/Kα intensity ratios and ΔE energy differences for Co, Ni, Cu, and Zn complexes. We tried to investigate chemical effects on central atoms using the behaviors of different ligands in these complexes. The experimental values of Kβ/Kα were compared with the theoretical and other experimental values of pure Co, Ni, Cu, and Zn.

  17. Correlation-Peak Imaging

    Science.gov (United States)

    Ziegler, A.; Metzler, A.; Köckenberger, W.; Izquierdo, M.; Komor, E.; Haase, A.; Décorps, M.; von Kienlin, M.

    1996-08-01

    Identification and quantitation in conventional1H spectroscopic imagingin vivois often hampered by the small chemical-shift range. To improve the spectral resolution of spectroscopic imaging, homonuclear two-dimensional correlation spectroscopy has been combined with phase encoding of the spatial dimensions. From the theoretical description of the coherence-transfer signal in the Fourier-transform domain, a comprehensive acquisition and processing strategy is presented that includes optimization of the width and the position of the acquisition windows, matched filtering of the signal envelope, and graphical presentation of the cross peak of interest. The procedure has been applied to image the spatial distribution of the correlation peaks from specific spin systems in the hypocotyl of castor bean (Ricinus communis) seedlings. Despite the overlap of many resonances, correlation-peak imaging made it possible to observe a number of proton resonances, such as those of sucrose, β-glucose, glutamine/glutamate, lysine, and arginine.

  18. Automated two-point dixon screening for the evaluation of hepatic steatosis and siderosis: comparison with R2*-relaxometry and chemical shift-based sequences

    Energy Technology Data Exchange (ETDEWEB)

    Henninger, B.; Rauch, S.; Schocke, M.; Jaschke, W.; Kremser, C. [Medical University of Innsbruck, Department of Radiology, Innsbruck (Austria); Zoller, H. [Medical University of Innsbruck, Department of Internal Medicine, Innsbruck (Austria); Kannengiesser, S. [Siemens AG, Healthcare Sector, MR Applications Development, Erlangen (Germany); Zhong, X. [Siemens Healthcare, MR R and D Collaborations, Atlanta, GA (United States); Reiter, G. [Siemens AG, Healthcare Sector, MR R and D Collaborations, Graz (Austria)

    2015-05-01

    To evaluate the automated two-point Dixon screening sequence for the detection and estimated quantification of hepatic iron and fat compared with standard sequences as a reference. One hundred and two patients with suspected diffuse liver disease were included in this prospective study. The following MRI protocol was used: 3D-T1-weighted opposed- and in-phase gradient echo with two-point Dixon reconstruction and dual-ratio signal discrimination algorithm (''screening'' sequence); fat-saturated, multi-gradient-echo sequence with 12 echoes; gradient-echo T1 FLASH opposed- and in-phase. Bland-Altman plots were generated and correlation coefficients were calculated to compare the sequences. The screening sequence diagnosed fat in 33, iron in 35 and a combination of both in 4 patients. Correlation between R2* values of the screening sequence and the standard relaxometry was excellent (r = 0.988). A slightly lower correlation (r = 0.978) was found between the fat fraction of the screening sequence and the standard sequence. Bland-Altman revealed systematically lower R2* values obtained from the screening sequence and higher fat fraction values obtained with the standard sequence with a rather high variability in agreement. The screening sequence is a promising method with fast diagnosis of the predominant liver disease. It is capable of estimating the amount of hepatic fat and iron comparable to standard methods. (orig.)

  19. Influence of electron correlation and degeneracy on the Fukui matrix and extension of frontier molecular orbital theory to correlated quantum chemical methods.

    Science.gov (United States)

    Bultinck, Patrick; Van Neck, Dimitri; Acke, Guillaume; Ayers, Paul W

    2012-02-21

    The Fukui function is considered as the diagonal element of the Fukui matrix in position space, where the Fukui matrix is the derivative of the one particle density matrix (1DM) with respect to the number of electrons. Diagonalization of the Fukui matrix, expressed in an orthogonal orbital basis, explains why regions in space with negative Fukui functions exist. Using a test set of molecules, electron correlation is found to have a remarkable effect on the eigenvalues of the Fukui matrix. The Fukui matrices at the independent electron model level are mathematically proven to always have an eigenvalue equal to exactly unity while the rest of the eigenvalues possibly differ from zero but sum to zero. The loss of idempotency of the 1DM at correlated levels of theory causes the loss of these properties. The influence of electron correlation is examined in detail and the frontier molecular orbital concept is extended to correlated levels of theory by defining it as the eigenvector of the Fukui matrix with the largest eigenvalue. The effect of degeneracy on the Fukui matrix is examined in detail, revealing that this is another way by which the unity eigenvalue and perfect pairing of eigenvalues can disappear.

  20. Sequential identification of model parameters by derivative double two-dimensional correlation spectroscopy and calibration-free approach for chemical reaction systems.

    Science.gov (United States)

    Spegazzini, Nicolas; Siesler, Heinz W; Ozaki, Yukihiro

    2012-10-02

    A sequential identification approach by two-dimensional (2D) correlation analysis for the identification of a chemical reaction model, activation, and thermodynamic parameters is presented in this paper. The identification task is decomposed into a sequence of subproblems. The first step is the construction of a reaction model with the suggested information by model-free 2D correlation analysis using a novel technique called derivative double 2D correlation spectroscopy (DD2DCOS), which enables one to analyze intensities with nonlinear behavior and overlapped bands. The second step is a model-based 2D correlation analysis where the activation and thermodynamic parameters are estimated by an indirect implicit calibration or a calibration-free approach. In this way, a minimization process for the spectral information by sample-sample 2D correlation spectroscopy and kinetic hard modeling (using ordinary differential equations) of the chemical reaction model is carried out. The sequential identification by 2D correlation analysis is illustrated with reference to the isomeric structure of diphenylurethane synthesized from phenylisocyanate and phenol. The reaction was investigated by FT-IR spectroscopy. The activation and thermodynamic parameters of the isomeric structures of diphenylurethane linked through a hydrogen bonding equilibrium were studied by means of an integration of model-free and model-based 2D correlation analysis called a sequential identification approach. The study determined the enthalpy (ΔH = 15.25 kJ/mol) and entropy (TΔS = 13.20 kJ/mol) of C═O···H hydrogen bonding of diphenylurethane through direct calculation from the differences in the kinetic parameters (δΔ(‡)H, -TδΔ(‡)S) at equilibrium in the chemical reaction system.

  1. Synthesis, antimicrobial evaluation and theoretical prediction of NMR chemical shifts of thiazole and selenazole derivatives with high antifungal activity against Candida spp.

    Science.gov (United States)

    Łączkowski, Krzysztof Z.; Motylewska, Katarzyna; Baranowska-Łączkowska, Angelika; Biernasiuk, Anna; Misiura, Konrad; Malm, Anna; Fernández, Berta

    2016-03-01

    Synthesis and investigation of antimicrobial activities of novel thiazoles and selenazoles is presented. Their structures were determined using NMR, FAB(+)-MS, HRMS and elemental analyses. To support the experiment, theoretical calculations of the 1H NMR shifts were carried out for representative systems within the DFT B3LYP/6-311++G** approximation which additionally confirmed the structure of investigated compounds. Among the derivatives, compounds 4b, 4h, 4j and 4l had very strong activity against reference strains of Candida albicans ATCC and Candida parapsilosis ATCC 22019 with MIC = 0.49-7.81 μg/ml. In the case of compounds 4b, 4c, 4h - 4j and 4l, the activity was very strong against of Candida spp. isolated from clinical materials, i.e. C. albicans, Candida krusei, Candida inconspicua, Candida famata, Candida lusitaniae, Candida sake, C. parapsilosis and Candida dubliniensis with MIC = 0.24-15.62 μg/ml. The activity of several of these was similar to the activity of commonly used antifungal agent fluconazole. Additionally, compounds 4m - 4s were found to be active against Gram-positive bacteria, both pathogenic staphylococci Staphylococcus aureus ATCC with MIC = 31.25-125 μg/ml and opportunistic bacteria, such as Staphylococcus epidermidis ATCC 12228 and Micrococcus luteus ATCC 10240 with MIC = 7.81-31.25 μg/ml.

  2. Unusual Physical and Chemical Properties of Ni in Ce1-xNixO2-y Oxides: Structural Characterization and Catalytic Activity for the Water Gas Shift Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Barrio, L.; Kubacka, A; Zhou, G; Estrella, M; Martinez-Arias, A; Hanson, J; Fernandez-Garcia, M; Rodriguez, J

    2010-01-01

    The structural and electronic properties of Ce{sub 1-x}Ni{sub x}O{sub 2-y} nanosystems prepared by a reverse microemulsion method were characterized with synchrotron-based X-ray diffraction, X-ray absorption spectroscopy, Raman spectroscopy, and density functional calculations. The Ce{sub 1-x}Ni{sub x}O{sub 2-y} systems adopt a lattice with a fluorite-type structure with an acute local order where Ni displays a strongly distorted (oxygen) nearest-neighbor coordination and the presence of Ni atoms as first cation distances, pointing to the existence of Ni-O-Ni entities embedded into the ceria lattice. A Ni {leftrightarrow} Ce exchange within the CeO{sub 2} leads to a charge redistribution and the appearance of O vacancies. The Ni-O bonds in Ce{sub 1-x}Ni{sub x}O{sub 2-y} are more difficult to reduce than the bonds in pure NiO. The specific structural configuration of Ni inside the mixed-metal oxide leads to a unique catalyst with a high activity for the water gas shift (CO + H{sub 2}O {yields} H{sub 2} + CO{sub 2}) reaction and a simultaneous reduction of the methanation activity of nickel. Characterization results indicate that small particles of metallic Ni at the interface position of a ceria network may be the key for high WGS activity and that the formate-carbonate route is operative for the production of hydrogen.

  3. Unusual Physical and Chemical Properties of Ni in Ce1-xNixO2-y Oxides: Structural Characterization and Catalytic Activity for the Water Gas Shift Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, J.A.; Barrio, L.; Kubacka, A.; Zhou, G.; Estrella, M.; Mart& #305; nez-Arias, A.; Hanson, J.C.; Fernandez-Garc& #305; a, M.

    2010-07-29

    The structural and electronic properties of Ce{sub 1-x}Ni{sub x}O{sub 2-y} nanosystems prepared by a reverse microemulsion method were characterized with synchrotron-based X-ray diffraction, X-ray absorption spectroscopy, Raman spectroscopy, and density functional calculations. The Ce{sub 1-x}Ni{sub x}O{sub 2-y} systems adopt a lattice with a fluorite-type structure with an acute local order where Ni displays a strongly distorted (oxygen) nearest-neighbor coordination and the presence of Ni atoms as first cation distances, pointing to the existence of Ni-O-Ni entities embedded into the ceria lattice. A Ni {leftrightarrow} Ce exchange within the CeO{sub 2} leads to a charge redistribution and the appearance of O vacancies. The Ni?O bonds in Ce{sub 1-x}Ni{sub x}O{sub 2-y} are more difficult to reduce than the bonds in pure NiO. The specific structural configuration of Ni inside the mixed-metal oxide leads to a unique catalyst with a high activity for the water gas shift (CO + H{sub 2}O {yields} H{sub 2} + CO{sub 2}) reaction and a simultaneous reduction of the methanation activity of nickel. Characterization results indicate that small particles of metallic Ni at the interface position of a ceria network may be the key for high WGS activity and that the formate?carbonate route is operative for the production of hydrogen.

  4. Iboga alkaloids from Peschiera affinis (Apocynaceae) - unequivocal {sup 1}H and {sup 13}C chemical shift assignments: antioxidant activity; Alcaloides iboga de Peschiera affinis (Apocynaceae) - atribuicao inequivoca dos deslocamentos quimicos dos atomos de hidrogenio e carbono: atividade antioxidante

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Allana Kellen L.; Magalhaes, Ticiane S.; Monte, Francisco Jose Q.; Mattos, Marcos Carlos de; Oliveira, Maria Conceicao F. de; Almeida, Maria Mozarina B.; Lemos, Telma L.G.; Braz-Filho, Raimundo [Universidade Federal do Ceara (UFC), Fortaleza, CE (Brazil). Dept. de Quimica Organica e Inorganica], e-mail: tlemos@dqoi.ufc.br

    2009-07-01

    Six known alkaloids iboga type and the triterpene {alpha}- and {beta}-amyrin acetate were isolated from the roots and stems of Peschiera affinis. Their structures were characterized on the basis of spectral data mainly NMR and mass spectra. 1D and 2D NMR spectra were also used to unequivocal {sup 1}H and {sup 13}C chemical shift assignments of alkaloids. The ethanolic extract of roots, alkaloidic and no-alkaloidic fractions and iso-voacristine hydroxyindolenine and voacangine were evaluated for their antioxidative properties using an autographic assay based on {beta}-carotene bleaching on TLC plates, and also spectrophotometric detection by reduction of the stable DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical. (author)

  5. Correlation between Biochemical Oxygen Demand and Chemical Oxygen Demand for Various Wastewater Treatment Plants in Egypt to Obtain the Biodegradability Indices

    OpenAIRE

    Khaled Zaher Abdallah; Gina Hammam

    2014-01-01

    Biochemical Oxygen Demand (BOD5) and Chemical Oxygen Demand (COD) are the most commonly used parameters for the characterization of wastewaters. Both of these parameters have advantages and disadvantages, and the choice usually depends on many factors such as the time period required to determine each one of them. It is essential to obtain a correlation between BOD5 and COD for various wastewater treatment plants, to help in the design and operation of these plants. In this paper, the biodegr...

  6. Hard X-ray photoelectron spectra (HXPES) of bulk non-conductor vitreous SiO{sub 2}: Minimum linewidths and surface chemical shifts

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Y.F., E-mail: Yongfeng.hu@lightsource.ca [Canadian Light Source, Saskatoon, SK (Canada); Xiao, Q.; Wang, D.; Cui, X. [Canadian Light Source, Saskatoon, SK (Canada); Nesbitt, H.W. [Department of Earth Sciences, University of Western Ontario, London, ONT (Canada); Bancroft, G.M. [Department of Chemistry, University of Western Ontario, London, ONT (Canada)

    2015-07-15

    Highlights: • Electronic structure of non-conducting glass studied by hard X-ray photoelectron spectroscopy. • A thin film of Cr was deposited on the vitreous SiO{sub 2} glass to overcome the sample charging. • Excellent O 1s and Si 1s linewidths were obtained, matching those reported using the laboratory based Kratos Axis Ultra spectrometer equipped with a magnetic compensation system. • The bulk and interface states of non-conducting samples are studied as a function of photon energy. - Abstract: Hard X-ray photoelectron spectra (2200 eV to 5000 eV photon energies) have been obtained for the first time on a bulk non-conductor, vitreous SiO{sub 2}, on a high resolution (E/ΔE of 10,000) synchrotron beamline at the Canadian Light Source (CLS). To minimize charging and differential charging, the SiO{sub 2} was coated with very thin layers (0.5 to 1.5 nm) of Cr metal. The O 1s linewidth obtained at 2500 eV photon energy was 1.26 eV—the minimum linewidth for SiO{sub 2}—and in good agreement with that obtained at 1486 eV on a Kratos Axis Ultra spectrometer equipped with a magnetic charge compensation system. The Si 1s linewidth of 1.5 eV, somewhat broader than that previously obtained at 1486 eV on the Si 2p{sub 3/2} line of 1.16 eV, is mainly due to the much larger inherent Si 1s linewidth (0.5 eV) compared to the inherent Si 2p linewidth (<0.1 eV). Both linewidths are dominated by the large final state vibrational broadening previously described. The Cr coating produces surface monolayers of interfacial Cr “suboxide” (Cr-subox), Cr metal, and a surface Cr oxide (Cr-surfox). Cr-subox (Si−O−Cr) gives rise to the weak near-surface Si 1s peak, while both oxides give rise to both the weak surface O 1s peak and the Cr 2p oxide peak. Both the O 1s and Si 1s surface peaks are shifted by ∼2 eV relative to the large bulk Si 1s and O 1s peaks. The weak Si 1s and O 1s surface peaks along with the Cr 2p oxide peak decrease in intensity greatly as the photon

  7. Randic and Schultz molecular topological indices and their correlation with some X-ray absorption parameters

    Science.gov (United States)

    Khatri, Sunil; Kekre, Pravin A.; Mishra, Ashutosh

    2016-10-01

    The properties of a molecular system are affected by the topology of molecule. Therefore many studies have been made where the various physic-chemical properties are correlated with the topological indices. These studies have shown a very good correlation demonstrating the utility of the graph theoretical approach. It is, therefore, very natural to expect that the various physical properties obtained by the X-ray absorption spectra may also show correlation with the topological indices. Some complexes were used to establish correlation between topological indices and some X-ray absorption parameters like chemical shift. The chemical shift is on the higher energy side of the metal edge in these complexes. The result obtained in these studies shows that the topological indices of organic molecule acting as a legands can be used for estimating edge shift theoretically.

  8. Intraspecific chemical diversity among neighbouring plants correlates positively with plant size and herbivore load but negatively with herbivore damage

    NARCIS (Netherlands)

    Bustos-segura, Carlos; Poelman, Erik H.; Reichelt, Michael; Gershenzon, Jonathan; Gols, Rieta; Scherber, Christoph

    2017-01-01

    Intraspecific plant diversity can modify the properties of associated arthropod communities and plant fitness. However, it is not well understood which plant traits determine these ecological effects. We explored the effect of intraspecific chemical diversity among neighbouring plants on the associa

  9. Correlation between chemical compounds and mechanical response in culms of two different ages of Guadua angustifolia Kunth

    OpenAIRE

    Luz Adriana Sánchez Echeverri; Giovanna Aita; Diana Robert; Mario Enrique Rodriguez Garcia

    2014-01-01

    Wet chemical analysis was used to determine carbohydrate structural contents, as well as ash and extractive contents on four Guadua Angustifolia Kunth forms ( f. Cebolla, f. Macana, f. Rayada Amarilla and f. Castilla ) with two different growth ages (young and mature). Soluble and insoluble fiber content was determined by using AOAC 985.29 method. Bending tests were conducted in a universal testing machine following ASTM D143 standard method in order to determine modulus of rupture ( MOR ). F...

  10. Evaluating the correlation between chemical and sensory compounds in Blaufränkisch and Cabernet Franc wines

    Directory of Open Access Journals (Sweden)

    Irina Balga

    2014-12-01

    Full Text Available The positive physiological effects of the bioactive compounds of red wines have been known for a long time. Besides that, the polyphenolic compounds of red wines represent one of the most important factors for oenology. With a special chemical analysis, we discover the relationship between chemical and sensory compounds. In this way, we explore which compounds influence sensory properties. The phenolic compounds are the quality attributes of the wine. The analysis of phenolic compounds was carried out in two red wines: Cabernet Franc and Blaufränkisch. The aim of this study was to analyse the chemical and organoleptic characteristics of these two wines and evaluate the connection between the two parameters. In addition, we also examined the influence of the polyphenolic content on sensory perception. The experiment was carried out in a cool climate wine region in Eger, Hungary, in vintage of 2008. We investigated the profile of phenolic contents in new and aged wines. Total polyphenolic content, anthocyanin, leucoanthocyanin and catechin were evaluated by spectrophotometer. Stilbenes were identified and quantified by high-performance liquid chromatography.

  11. On the calculation of Mossbauer isomer shift

    NARCIS (Netherlands)

    Filatov, Michael

    2007-01-01

    A quantum chemical computational scheme for the calculation of isomer shift in Mossbauer spectroscopy is suggested. Within the described scheme, the isomer shift is treated as a derivative of the total electronic energy with respect to the radius of a finite nucleus. The explicit use of a finite nuc

  12. Monazite chemical age and composition correlations, an insight in the Palaeozoic evolution of the Leaota Massif, South Carpathians

    Science.gov (United States)

    Săbău, Gavril; Negulescu, Elena

    2015-04-01

    Notwithstanding remarkable advantages of monazite microprobe U-Th-PbT geochronology of metamorphic formations, such as the direct investigation of a metamorphic mineral in a truly in situ setting, unequalled spatial resolution, and cost-effective analyses, it essentially remains affected by indeterminations as regards the accuracy and the representativity of the results. Besides the experimental hurdles related to trace element analyses with the microprobe (sensitivity, background and overlap effects) the method faces two main biases, firstly its inherently blind status emerging from the aprioric assumption of isotopic equilibrium, and secondly the marked susceptibility of monazite to fluid-stimulated chemical recrystallization and compositional resetting (e. g. Kelly et al. 2012). Age spectra obtained from individual sampled habitually display a significant scatter of calculated age data, in such a way that the separation of coherent and geologically relevant populations may often represent a substantial challenge. The interpretation of the results greatly benefits from the qualitative analysis of the textural and paragenetic setting or a trial-and error quantitative statistical assessment of distinct age clusters (Montel et al., 1996), though still maintaining a variable degree of subjectivity, as in any interpretative process not fully sustained by quantitative analysis. Additional dependable support can be gained from further qualitative parameters characterizing, besides the distribution of individual age data, also the global chemical composition of the analysed monazite grains, as well as the relationship to the corresponding metamorphic assemblages (Săbău & Negulescu, 2013). The quantitative assessment of the age patterns of individual samples can be achieved by plotting the normalized age gradient from the sorted age pattern, allowing distinction of quasi-gaussian distribution domains likely to correspond to coherent age clusters of geologic significance

  13. Correlation between the Inhibition of Positronium Formation by Scavenger Molecules, and Chemical Reaction Rate of Electrons with these Molecules in Nonpolar Liquids

    DEFF Research Database (Denmark)

    Levay, B.; Mogensen, O. E.

    1977-01-01

    o-Ps yields were determined in various liquid hydrocarbons, tetramethylsilane, and mixtures thereof as a function of C2H5Br and CCll concentration. These molecules are known to be good electron scavengers and positronium inhibitors as well. The spur reaction model of Ps formation predicts...... a correlation between the inhibition coefficient and the chemical rate constant of electrons with scavenger molecules. We found that the dependence of the inhibition coefficient on the work function (VOo)f electrons in different liquids shows a very unusual behavior, similar to that recently found...... for the chemical rate constants of quasifree electrons with the same scavenger molecules. The inhibition coefficient as a function of Vo had a maximum for C2HsBr, while it increased monotonously with decreasing V, for CC14. The inhibition coefficient for C2H5Br in a 1:l molar tetramethylsilane...

  14. An attempt to correlate surface physics with chemical properties: molecular beam and Kelvin probe investigations of Ce1-xZrxO2 thin films.

    Science.gov (United States)

    Kolekar, Sadhu K; Dubey, Anjani; Date, Kalyani S; Datar, Suwarna; Gopinath, Chinnakonda S

    2016-10-05

    What is the correlation between physical properties of the surfaces (such as surface potential, electronic nature of the surface), and chemical and catalysis properties (such as chemisorption, sticking probability of surface)? An attempt has been made to explore any correlation that might exist between the physical and chemical properties of thin film surfaces. Kelvin probe microscopy (KPM) and the molecular beam (MB) methods were employed to carry out the surface potential, and oxygen adsorption and oxygen storage capacity (OSC) measurements on Ce1-xZrxO2 thin films. A sol-gel synthesis procedure and spin-coating deposition method have been applied to make continuous nanocrystalline Ce1-xZrxO2 (x = 0-1) (CZ) thin films with uniform thickness (35-50 nm); however, surface roughness and porosity inherently changes with CZ composition. MB studies of O2 adsorption on CZ reveal high OSC for Ce0.9Zr0.1O2, which also exhibits highly porous and significantly rough surface characteristics. The surface potential observed from KPM studies varied between 30 and 80 mV, with Ce-rich compositions exhibiting the highest surface potential. Surface potential shows large changes after reduction or oxidation of the CZ film demonstrating the influence of Ce(3+)/Ce(4+) on surface potential, which is also a key to catalytic activity for ceria-based catalysts. The surface potential measured from KPM and the OSC measured from MB vary linearly and they depend on the Ce(3+)/Ce(4+) ratio. More and detailed studies are suggested to arrive at a correlation between the physical and chemical properties of the surfaces.

  15. Chemical composition of scales generated from oil industry and correlation to radionuclide contents and gamma-ray measurements of (210)Pb.

    Science.gov (United States)

    Al Attar, Lina; Safia, Bassam; Abdul Ghani, Basem

    2016-03-01

    Scale generated from the maintenance of equipment contaminated by naturally occurring radioactive materials may contain also chemical components that cause hazardous pollution to human health and the environment. This study spotlights the characterisation of chemical pollutants in scales in relation to home-made comparison samples as no reference material for such waste exists. Analysis by energy dispersive x-ray fluorescence, with accuracy and precision better than 90%, revealed that barium was the most abundant element in scale samples, ranging from 1.4 to 38.2%. The concentrations of the toxic elements such as lead and chromium were as high as 2.5 and 1.2% respectively. Statistically, high correlation was observed between the concentration of Ba and Sr, sample density, radionuclide contents ((210)Pb and (226)Ra) and self-attenuation factor used for the radio-measurements. However, iron showed a reverse correlation. Interpretation of data with regards to the mineralogical components indicated that (226)Ra and (210)Pb co-precipitated with the insoluble salt Ba0.75Sr0.25SO4. Since both Ba and Sr have high Z, samples of high density (ρ) were accompanied with high values of self-attenuation correction factors (Cf) for the emitted radiation; correlation matrix of Pearson reached 0.935 between ρ and Cf. An attempt to eliminate the effect of the elemental composition and improve gamma measurements of (210)Pb activity concentration in scale samples was made, which showed no correction for self-attenuation was needed when sample densities were in the range 1.0-1.4 g cm(-3). For denser samples, a mathematical model was developed. Accurate determinations of radionuclide and chemical contents of scale would facilitate future Environmental Impact Assessment for the petroleum industry.

  16. Xinjiang Guanghui Shifts to Coal Chemical Business

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ Xinjiang Guanghui Industry Co., Ltd.(Xinjiang Guanghui, SH: 600256) was established on April 10th, 1999. It is located in Urumqi Economic and Technological Development Zone,Xinjiang of western China. The company got listed in Shanghai Stock Exchange on May 26th, 2000.

  17. The local free volume and its correlation with the structural, chemical and dynamic properties of branched polymers, polymer electrolytes, highly oriented polyethylene fibres and other polymers

    CERN Document Server

    Bamford, D

    2002-01-01

    The work described in this thesis is concerned with the study of the local free volume measured by Positron Annihilation Spectroscopy and its correlation with the physical, chemical and structural properties of polymers. The average size of the local free volume holes in branched poly(ethylene-co-olefin) and poly(propylene-co-olefin) copolymers is studied using Positron Annihilation Lifetime Spectroscopy PALS and correlated with the number and length of the branches and the physical properties determined from Differential Scanning Calorimetry DSC and density measurements. The presence of the n-alkyl branches were found to form sterical hindrances to an effective chain packing resulting in a linear increase in the average free volume hole sizes, an increase in the specific volume of the amorphous phase, a decrease in the sample crystallinity and a decrease in the glass transition and melting temperatures. A linear relation was found between the average size of the free volume holes and the glass transition tem...

  18. Variable angle correlation spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Y K [Univ. of California, Berkeley, CA (United States)

    1994-05-01

    In this dissertation, a novel nuclear magnetic resonance (NMR) technique, variable angle correlation spectroscopy (VACSY) is described and demonstrated with {sup 13}C nuclei in rapidly rotating samples. These experiments focus on one of the basic problems in solid state NMR: how to extract the wealth of information contained in the anisotropic component of the NMR signal while still maintaining spectral resolution. Analysis of the anisotropic spectral patterns from poly-crystalline systems reveal information concerning molecular structure and dynamics, yet in all but the simplest of systems, the overlap of spectral patterns from chemically distinct sites renders the spectral analysis difficult if not impossible. One solution to this problem is to perform multi-dimensional experiments where the high-resolution, isotropic spectrum in one dimension is correlated with the anisotropic spectral patterns in the other dimensions. The VACSY technique incorporates the angle between the spinner axis and the static magnetic field as an experimental parameter that may be incremented during the course of the experiment to help correlate the isotropic and anisotropic components of the spectrum. The two-dimensional version of the VACSY experiments is used to extract the chemical shift anisotropy tensor values from multi-site organic molecules, study molecular dynamics in the intermediate time regime, and to examine the ordering properties of partially oriented samples. The VACSY technique is then extended to three-dimensional experiments to study slow molecular reorientations in a multi-site polymer system.

  19. Development of microsatellite markers and their correlation with morphological and chemical markers in Withania somnifera (L. Dunal

    Directory of Open Access Journals (Sweden)

    Punit Kumar Khanna

    2016-04-01

    Full Text Available The genetic variation and relationships among 14 Withania accessions were evaluated using morphological, chemical and Simple Sequence Repeat (SSR markers. Wild accessions are more robust and better performing in morphological and chemical metabolite accumulation than cultivated one. The results revealed that out of fourteen, four primers showed distinct polymorphism, indicating the robust nature of microsatellites in revealing polymorphism. The banding pattern was recorded in the form of 0-1 data sheet which was analyzed using unweighted pair group method with arithmetic mean (UPGMA based on Jaccard's similarity coefficient. The cluster analysis showed higher level of genetic variation among the accessions. Similarity coefficients ranged from 0.125 to 1. The dendrogram revealed 3 major distinct clusters. Higher range of similarity values for related genotypes using simple sequence repeats (SSR provides greater confidence for the assessment of genetic diversity and relationships. The polymorphism information content (PIC value for the SSR loci ranged from 0.0 to 0.40. Higher PIC values were associated with higher level of polymorphism. Results of this study showed a high degree of variation among analyzed accessions, indicating an important source of genetic diversity that can be used in future breeding programs.

  20. Chemical profiling and adulteration screening of Aquilariae Lignum Resinatum by Fourier transform infrared (FT-IR) spectroscopy and two-dimensional correlation infrared (2D-IR) spectroscopy

    Science.gov (United States)

    Qu, Lei; Chen, Jian-bo; Zhang, Gui-Jun; Sun, Su-qin; Zheng, Jing

    2017-03-01

    As a kind of expensive perfume and valuable herb, Aquilariae Lignum Resinatum (ALR) is often adulterated for economic motivations. In this research, Fourier transform infrared (FT-IR) spectroscopy is employed to establish a simple and quick method for the adulteration screening of ALR. First, the principal chemical constituents of ALR are characterized by FT-IR spectroscopy at room temperature and two-dimensional correlation infrared (2D-IR) spectroscopy with thermal perturbation. Besides the common cellulose and lignin compounds, a certain amount of resin is the characteristic constituent of ALR. Synchronous and asynchronous 2D-IR spectra indicate that the resin (an unstable secondary metabolite) is more sensitive than cellulose and lignin (stable structural constituents) to the thermal perturbation. Using a certified ALR sample as the reference, the infrared spectral correlation threshold is determined by 30 authentic samples and 6 adulterated samples. The spectral correlation coefficient of an authentic ALR sample to the standard reference should be not less than 0.9886 (p = 0.01). Three commercial adulterated ALR samples are identified by the correlation threshold. Further interpretation of the infrared spectra of the adulterated samples indicates the common adulterating methods - counterfeiting with other kind of wood, adding ingredient such as sand to increase the weight, and adding the cheap resin such as rosin to increase the content of resin compounds. Results of this research prove that FT-IR spectroscopy can be used as a simple and accurate quality control method of ALR.

  1. Chemical profiling and adulteration screening of Aquilariae Lignum Resinatum by Fourier transform infrared (FT-IR) spectroscopy and two-dimensional correlation infrared (2D-IR) spectroscopy.

    Science.gov (United States)

    Qu, Lei; Chen, Jian-Bo; Zhang, Gui-Jun; Sun, Su-Qin; Zheng, Jing

    2017-03-05

    As a kind of expensive perfume and valuable herb, Aquilariae Lignum Resinatum (ALR) is often adulterated for economic motivations. In this research, Fourier transform infrared (FT-IR) spectroscopy is employed to establish a simple and quick method for the adulteration screening of ALR. First, the principal chemical constituents of ALR are characterized by FT-IR spectroscopy at room temperature and two-dimensional correlation infrared (2D-IR) spectroscopy with thermal perturbation. Besides the common cellulose and lignin compounds, a certain amount of resin is the characteristic constituent of ALR. Synchronous and asynchronous 2D-IR spectra indicate that the resin (an unstable secondary metabolite) is more sensitive than cellulose and lignin (stable structural constituents) to the thermal perturbation. Using a certified ALR sample as the reference, the infrared spectral correlation threshold is determined by 30 authentic samples and 6 adulterated samples. The spectral correlation coefficient of an authentic ALR sample to the standard reference should be not less than 0.9886 (p=0.01). Three commercial adulterated ALR samples are identified by the correlation threshold. Further interpretation of the infrared spectra of the adulterated samples indicates the common adulterating methods - counterfeiting with other kind of wood, adding ingredient such as sand to increase the weight, and adding the cheap resin such as rosin to increase the content of resin compounds. Results of this research prove that FT-IR spectroscopy can be used as a simple and accurate quality control method of ALR.

  2. Do differences in chemical composition of stem and cap of Amanita muscaria fruiting bodies correlate with topsoil type?

    Science.gov (United States)

    Deja, Stanisław; Wieczorek, Piotr P; Halama, Marek; Jasicka-Misiak, Izabela; Kafarski, Paweł; Poliwoda, Anna; Młynarz, Piotr

    2014-01-01

    Fly agaric (Amanita muscaria) was investigated using a 1H NMR-based metabolomics approach. The caps and stems were studied separately, revealing different metabolic compositions. Additionally, multivariate data analyses of the fungal basidiomata and the type of soil were performed. Compared to the stems, A. muscaria caps exhibited higher concentrations of isoleucine, leucine, valine, alanine, aspartate, asparagine, threonine, lipids (mainly free fatty acids), choline, glycerophosphocholine (GPC), acetate, adenosine, uridine, 4-aminobutyrate, 6-hydroxynicotinate, quinolinate, UDP-carbohydrate and glycerol. Conversely, they exhibited lower concentrations of formate, fumarate, trehalose, α- and β-glucose. Six metabolites, malate, succinate, gluconate, N-acetylated compounds (NAC), tyrosine and phenylalanine, were detected in whole A. muscaria fruiting bodies but did not show significant differences in their levels between caps and stems (P value>0.05 and/or OPLS-DA loading correlation coefficient muscaria from mineral and mineral-organic topsoil. Moreover, the metabolomic approach and multivariate tools enabled to ascribe the basidiomata of fly agaric to the type of topsoil. Obtained results revealed that stems metabolome is more dependent on the topsoil type than caps. The correlation between metabolites and topsoil contents together with its properties exhibited mutual dependences.

  3. Do differences in chemical composition of stem and cap of Amanita muscaria fruiting bodies correlate with topsoil type?

    Directory of Open Access Journals (Sweden)

    Stanisław Deja

    Full Text Available Fly agaric (Amanita muscaria was investigated using a 1H NMR-based metabolomics approach. The caps and stems were studied separately, revealing different metabolic compositions. Additionally, multivariate data analyses of the fungal basidiomata and the type of soil were performed. Compared to the stems, A. muscaria caps exhibited higher concentrations of isoleucine, leucine, valine, alanine, aspartate, asparagine, threonine, lipids (mainly free fatty acids, choline, glycerophosphocholine (GPC, acetate, adenosine, uridine, 4-aminobutyrate, 6-hydroxynicotinate, quinolinate, UDP-carbohydrate and glycerol. Conversely, they exhibited lower concentrations of formate, fumarate, trehalose, α- and β-glucose. Six metabolites, malate, succinate, gluconate, N-acetylated compounds (NAC, tyrosine and phenylalanine, were detected in whole A. muscaria fruiting bodies but did not show significant differences in their levels between caps and stems (P value>0.05 and/or OPLS-DA loading correlation coefficient <0.4. This methodology allowed for the differentiation between the fruiting bodies of A. muscaria from mineral and mineral-organic topsoil. Moreover, the metabolomic approach and multivariate tools enabled to ascribe the basidiomata of fly agaric to the type of topsoil. Obtained results revealed that stems metabolome is more dependent on the topsoil type than caps. The correlation between metabolites and topsoil contents together with its properties exhibited mutual dependences.

  4. Correlation between the inhibition of positronium formation by scavenger molecules, and chemical reaction rate of electrons with these molecules in nonpolar liquids

    Energy Technology Data Exchange (ETDEWEB)

    Levay, B.; Mogensen, O.E.

    1977-03-10

    o-Ps yields were determined in various liquid hydrocarbons, tetramethylsilane, and mixtures thereof as a function of C/sub 2/H/sub 5/Br and CCl/sub 4/ concentration. These molecules are known to be good electron scavengers and positronium inhibitors as well. The spur reaction model of Ps formation predicts a correlation between the inhibition coefficient and the chemical rate constant of electrons with scavenger molecules. We found that the dependence of the inhibition coefficient on the work function (V/sub 0/) of electrons in different liquids shows a very unusual behavior, similar to that recently found for the chemical rate constants of quasifree electrons with the same scavenger molecules. The inhibition coefficient as a function of V/sub 0/ had a maximum for C/sub 2/H/sub 5/Br, while it increased monotonously with decreasing V/sub 0/ for CCl/sub 4/. The inhibition coefficient for C/sub 2/H/sub 5/Br in a 1 : 1 molar tetramethylsilane-n-tetradecane mixture was found to be greater than in both of the pure components. The clear correlation found between electron scavenging rate constants and positronium inhibition constitutes the severest test to date of the spur reaction model of positronium formation. The importance of the positron annihilation method from the point of view of radiation chemistry is also emphasized.

  5. Theoretical NMR correlations based Structure Discussion

    Directory of Open Access Journals (Sweden)

    Junker Jochen

    2011-07-01

    Full Text Available Abstract The constitutional assignment of natural products by NMR spectroscopy is usually based on 2D NMR experiments like COSY, HSQC, and HMBC. The actual difficulty of the structure elucidation problem depends more on the type of the investigated molecule than on its size. The moment HMBC data is involved in the process or a large number of heteroatoms is present, a possibility of multiple solutions fitting the same data set exists. A structure elucidation software can be used to find such alternative constitutional assignments and help in the discussion in order to find the correct solution. But this is rarely done. This article describes the use of theoretical NMR correlation data in the structure elucidation process with WEBCOCON, not for the initial constitutional assignments, but to define how well a suggested molecule could have been described by NMR correlation data. The results of this analysis can be used to decide on further steps needed to assure the correctness of the structural assignment. As first step the analysis of the deviation of carbon chemical shifts is performed, comparing chemical shifts predicted for each possible solution with the experimental data. The application of this technique to three well known compounds is shown. Using NMR correlation data alone for the description of the constitutions is not always enough, even when including 13C chemical shift prediction.

  6. 绶草内生真菌化学成分相关性的研究%Correlations of chemical constituents in endophyte isolated from Spiranthes sinensis

    Institute of Scientific and Technical Information of China (English)

    程玉鹏; 匡海学; 高宁; 胡凤; 侯素云; 王振月

    2011-01-01

    Objective To discuss correlations between the chemical constituents of different endophytic fungi and their host and provide basis of researching the mechanism of some endophytic fungi which have the abilities to produce the same or similar chemical constituents as their host plant product. Methods Chemical compounds derived from the endophytic fungi and their host Spiramthes sinensis were tested by HPLC, and the correlation data were analysed by SPSS16.0. Results The clustering is not obvious between petroleum ether extracts of fungi; the result of study on the ethyl acetate extracts and water-saturated n-butanol extracts showed that fungi isolated from the same organ tended to cluster together and the same species fungi tended to cluster together. Conclusion Correlation among the petroleum ether extracts of the fungi is not obvious. The correlation between the ethyl acetate extracts are the most obvious in organ from which the fungi isolated and within the species.%目的 探讨绶草内生真菌与其宿主化学成分的相关性,为阐明药用植物真菌与宿主植物产生相同或相似化学成分的机制奠定基础.方法 采用HPLC法对绶草及其内生真菌各提取部位进行色谱分析,并利用SPSS16.0软件对色谱结果进行聚类,得到绶草内生真菌之间化学成分的相关性.结果 绶草内生真菌石油醚提取物的聚类规律不明显;醋酸乙酯提取物及水饱和正丁醇提取物均表现为分离自同一部位的真菌倾向于聚类在同一分支,相同种属的内生真菌同样倾向于聚类在同一分支,且以醋酸乙酯提取物表现最为明显.结论 绶草内生真菌石油醚提取物之间的相关性最小,醋酸乙酯提取物与真菌分离部位相关性最为明显,与真菌的种属同样存在较大的相关性.

  7. On some hydrogen bond correlations at high pressures

    Science.gov (United States)

    Sikka, S. K.

    2007-09-01

    In situ high pressure neutron diffraction measured lengths of O H and H O pairs in hydrogen bonds in substances are shown to follow the correlation between them established from 0.1 MPa data on different chemical compounds. In particular, the conclusion by Nelmes et al that their high pressure data on ice VIII differ from it is not supported. For compounds in which the O H stretching frequencies red shift under pressure, it is shown that wherever structural data is available, they follow the stretching frequency versus H O (or O O) distance correlation. For compounds displaying blue shifts with pressure an analogy appears to exist with improper hydrogen bonds.

  8. Effects of humic substances on the bioconcentration of polycyclic aromatic hydrocarbons: Correlations with spectroscopic and chemical properties of humic substances

    Science.gov (United States)

    Haitzer, M.; Abbt-Braun, G.; Traunspurger, W.; Steinberg, C.E.W.

    1999-01-01

    The presence of dissolved humic substances (HS, fulvic and humic acids) generally reduces the uptake of hydrophobic organic compounds into aquatic organisms. The extent of this effect depends both on the concentration and on the origin of the HS. The aim of this study was to investigate the role of qualitative differences between HS from different origins. The effects of seven different HS on the bioconcentration of pyrene and benzo[a]pyrene (BaP) in the nematode Caenorhabditis elegans were related to the spectroscopic and chemical properties of the HS. The effect of each humic material on the bioconcentration of pyrene or BaP was quantified as a 'biologically determined' partition coefficient K(DOC). We observed significant linear relationships between K(DOC) and the atomic H/C ratio, the specific absorptivity at 254 nm, the content of aromatic carbons (as determined by 13C nuclear magnetic resonance spectroscopy, the copper-complexing capacity, the content of phenolic OH groups, and the molecular weight of the HS. There was no discernible relationship of K(DOC) with the atomic (N + O)/C ratio, an indicator of the polarity of HS. Taken together, our results show that the variability in the effects of HS from different origins could be related to variations in bulk properties of the HS. Parameters describing the aromaticity of the humic materials seemed to be most useful for estimating effects of HS on the bioconcentration of pyrene and BaP.

  9. Sectoral Shifts and Cyclical Fluctuations Sectoral Shifts and Cyclical Fluctuations

    Directory of Open Access Journals (Sweden)

    Richard Rogerson

    1991-03-01

    Full Text Available Sectoral Shifts and Cyclical Fluctuations This paper studies a two sector real business cycle model in which the sectors experience different trend rates of growth and labor mobility is costly. Predictions are derived concerning the correlation between sectoral reallocation of workers and the cycle. This correlation may be positive or negative depending upon whether the growing sector displays larger or smaller fluctuations than the shrinking sector. The post- World War II period has witnessed two major patterns of sectoral change in industrialized countries: movement out of agriculture and movement out of the industrial sector. The model's basic prediction is shown to be consistent with the observed pattern of reallocation.

  10. 磁共振梯度双回波化学位移成像定量诊断脂肪肝的临床应用%Clinical application of MR dual-echo chemical shift gradient-echo imaging in quantitative diagnosis of fatty liver

    Institute of Scientific and Technical Information of China (English)

    徐东风; 施蒋巍; 沈莉; 戴鸿志; 赵雪文; 刘利; 沈一易; 刘柯柯; 李曼

    2011-01-01

    目的 探讨磁共振梯度双回波化学位移成像定量诊断脂肪肝的临床应用.方法 20例弥漫性脂肪肝病例,同期行CT及磁共振梯度双回波化学位移成像,分别对肝VI段及IV段(Couinaud法)选取同一部位感兴趣区进行测量.正反相位信号强度差/正相位信号强度(SIP-SOP)/SIP及正反相位信号强度差SIP-SOP与肝/脾CT值比值(L/S)进行Spearman相关性分析及建立直线回归方程.根据L/S评价脂肪肝程度的标准,计算(SIP-SOP)/SIP、SIP-SOP评价脂肪肝程度的标准.结果 (SIP-SOP)/SIP、SIP-SOP与L/S的相关系数分别是r=-0.908及r=-0.844(P(SIP-SOP)/SIP≥0.159、中度0.444>(SIP-SOP)/SIP≥0.329,重度为(SIP-SOP)/SIP≥0.444.SIP-SOP诊断脂肪肝的标准为轻度:193.0>SIP-SOP≥3.2,中度:319.6>SIP-SOP≥193.0,重度:SIP-SOP≥319.6.结论 磁共振梯度双回波化学位移技术与CT定量诊断脂肪肝具有较好的相关性,可成为临床定量诊断脂肪肝的一种简单、有效方法.%Objective To evaluate the clinical application of MR dual-echo chemical shift gradient-echo imaging in quantitative diagnosis of fatty liver. Methods 20 patients with diffused fatty liver underwent CT and MR dual-echo chemical shift gradient-echo imaging simutaneously. The liver segments (Couinaud) VI and IV were selected separately at region of interest (ROI) in the same site to study the relationship between(Sip -Sop )/Sip ,Sip - Sop and L/S (Sip :signal intensity of in-phase, Sop :signal intensity of out-phase, L/S: CT attenuation ratio of liver to spleen) using Spearman correlation coefficient and linear regression equation. The diagnostic criteria of fatty liver using(Sip-Sop)/Sip and Sip - Sop were calculated refer to the criteria of L/S. Results (Sip - Sop)/Sip and Sip - Sop had significant relationship with L/S(r= -0. 908 and r= -0. 844 ,P(S,P - Sop )/S,P>0. 159,moderate level :0. 444>(S,P - Sop ) /S,P>0. 329 and severe level; (S,P-Sop )/SipS?0. 444 ,and the diagnostic

  11. PM2.5 chemical composition at a rural background site in Central Europe, including correlation and air mass back trajectory analysis

    Science.gov (United States)

    Schwarz, Jaroslav; Cusack, Michael; Karban, Jindřich; Chalupníčková, Eva; Havránek, Vladimír; Smolík, Jiří; Ždímal, Vladimír

    2016-07-01

    PM2.5 mass concentrations and chemical compositions sampled over a 13-month period at a Central European rural background site (Košetice) are presented in this work. A comprehensive chemical analysis of PM2.5 was performed, which provided elemental composition (Al, Si, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Br, Rb, Sr, Y, Zr, and Pb) and the concentration of water-soluble inorganic anions (SO42 -, NO3-. Cl-, NO2-, Br-, and H2PO4-) and cations (Na+, NH4+, K+, Ca2 +, and Mg2 +), elemental and organic carbon (EC and OC), and levoglucosan. Spearman correlation coefficients between individual chemical species and particle number concentrations were calculated for the following six size ranges: 10-25 nm (N10-25), 25-50 nm (N25-50), 50-80 nm (N50-80), 80-150 nm (N80-150), 150-300 nm (N150-300), and 300-800 nm (N300-800). Average concentrations of individual species were comparable with concentrations reported from similar sites across Central Europe. Organic matter (OM) accounted for 45% of the PM2.5 mass (calculated from OC by a factor of 1.6), while the second most common component were secondary aerosols (SO42 -: 19%, NO3-: 14%, NH4+: 10%), which accounted for 43% of the mass. Based on levoglucosan analysis, 31% of OM was attributed to emissions associated with biomass burning (OMBB). EC concentrations, determined using the EUSAAR_2 thermal optical protocol, contributed 4% to PM2.5 mass. A total of 1% of the mass was attributed to a mineral matter source, while the remaining 6% was from an undetermined mass. Seasonal variations showed highest concentrations of NO3- and OMBB in winter, nitrate share in spring, and an increase in percentage of SO42 - and mineral matter in summer. The largest seasonal variation was found for species associated with wood and coal combustion (levoglucosan, K+, Zn, Pb, As), which had clear maxima during winter. Correlation analysis of different size fraction particle number concentrations was used to distinguish the influence

  12. Constituintes químicos de Ottonia corcovadensis Miq. da floresta Amazônica: atribuição dos deslocamentos químicos dos átomos de hidrogênio e carbono Chemical constituents of Ottonia corcovadensis Miq. from Amazon forest: ¹h and 13c chemical shift assignments

    Directory of Open Access Journals (Sweden)

    Valdir A. Facundo

    2004-02-01

    Full Text Available In an ethanolic extract of leaves of Ottonia corcovadensis (Piperaceae were identified sixteen terpenoids of essential oil and the three flavonoids 3',4',5,5',7-pentamethoxyflavone (1, 3',4',5,7-tetramethoxyflavone (2 and 5-hydroxy-3',4',5',7-tetramethoxyflavone (3 and cafeic acid (4. Two amides (5 and 6 were isolated from an ethanolic extract of the roots. The structures were established by spectral analysis, meanly NMR (1D and 2D and mass spectra. Extensive NMR analysis was also used to complete ¹H and 13C chemical shift assignments of the flavonoids and amides. The components of the essential oil were identified by computer library search, retention indices and visual interpretation of mass spectra.

  13. Correlation, sedimentology, structural setting, chemical composition, and provenance of selected formations in Mesoproterozoic Lemhi Group, central Idaho

    Science.gov (United States)

    Tysdal, Russell G.; Lindsey, David A.; Taggart, Joseph E.

    2003-01-01

    A unit of the Mesoproterozoic Apple Creek Formation of the Lemhi Range previously was correlated with part of the lower subunit of the Mesoproterozoic Yellowjacket Formation in the Salmon River Mountains. Strata currently assigned to the middle subunit of the Yellowjacket Formation lie conformably above the Apple Creek unit in the Salmon River Mountains, and are here renamed the banded siltite unit and reassigned to the Apple Creek Formation. Almost all of the banded siltite unit is preserved within the Salmon River Mountains, where it grades upward into clastic rocks that currently are assigned to the upper subunit of the Yellowjacket Formation and that here are reassigned to the Gunsight Formation. The banded siltite unit of the Apple Creek Formation is composed of a turbidite sequence, as recognized by previous workers. Uppermost strata of the unit were reworked by currents, possibly storm generated, and adjusted to a high water content by developing abundant soft-sediment deformation features. Basal strata of the overlying Gunsight Formation in the Salmon River Mountains display abundant hummocky crossbeds, storm-generated features deposited below fair-weather wave base, that are conformable above the storm-reworked deposits. The hummocky crossbedded strata grade upward into marine shoreface strata deposited above fair-weather wave base, which in turn are succeeded by fluvial strata. Hummocky and shoreface strata are absent from the Gunsight Formation in the Lemhi Range. The major thickness of the Gunsight Formation in both the Salmon River Mountains and the Lemhi Range is composed of fluvial rocks, transitional in the upper part into marine rocks of the Swauger Formation. The fluvial strata are mainly characterized by stacked sheets of metasandstone and coarse siltite; they are interpreted as deposits of braided rivers. The Poison Creek thrust fault of the Lemhi Range extends northwestward through the study area in the east-central part of the Salmon River

  14. Effects of surgical and chemical lesions on striatal (/sup 3/H)threo-(+-)-methylphenidate binding: correlation with (/sup 3/H)dopamine uptake

    Energy Technology Data Exchange (ETDEWEB)

    Janowsky, A.; Berger, P.; Long, R.; Paul, S.M. (National Inst. of Mental Health, Bethesda, MD (USA)); Schweri, M.M.; Skolnick, P. (National Institutes of Health, Bethesda, MD (USA))

    1985-01-22

    The specific binding of (/sup 3/H)threo-(+-)-methylphenidate to membranes prepared from rat striatum was significantly reduced following either surgical lesions of the medial forebrain bundle or intracerebroventricular administration of 6-hydroxydopamine. The decrease in the density of (/sup 3/H)threo-(+-)-methylphenidate binding sites in striatum following chemical or surgical denervation was highly correlated with the decrease in (/sup 3/H)dopamine uptake. In contrast, intracerebroventricular administration of 5,7-dihydroxytryptamine, AF64A, or chronic parenteral administration of reserpine did not alter either the number or apparent affinity of (/sup 3/H)threo-(+-)-methylphenidate binding sites. These data suggest that the specific binding sites for (/sup 3/H)threo-(+-)-methylphenidate in striatum are localized to dopaminergic nerve terminals, and may be associated with the dopamine transport complex.

  15. Corrosion inhibition of mild steel in acidic media using newly synthesized heterocyclic organic molecules: Correlation between inhibition efficiency and chemical structure

    Energy Technology Data Exchange (ETDEWEB)

    Ouici, H. B., E-mail: ouici.houari@yahoo.fr; Guendouzi, A., E-mail: guendouzzi@yahoo.fr [Departement of Chimistry, Faculty of Sciences, University of Saïda (Algeria); Benali, O. [Department of Biology, Faculty of Science, University of Saida (Algeria)

    2015-03-30

    The corrosion inhibition of mild steel in 5% HCl solutions by some new synthesized organic compounds namely 3-(2-methoxyphenyl) 5-mercapto-1. 2. 4-triazole (2-MMT), 3-(3-methoxyphenyl) 5-mercapto-1. 2. 4-triazole (3-MMT) and 3-(2-hydroxyphenyl) 5-mercapto-1. 2. 4-triazole (2-HMT) was investigated using weight loss and potentiostatic polarization techniques. These measurements reveal that the inhibition efficiency obtained by these compounds increased by increasing their concentration. The inhibition efficiency follows the order 2-MMT >3-MMT >2-HMT. Polarization studies show that these compounds are of the mixed type but dominantly act as a cathodic inhibitors for mild steel in 5% HCl solutions. These inhibitors function through adsorption following Langmuir isotherm. Activation energy and Gibbs free energy for adsorption of inhibitors are calculated. Molecular modeling has been conducted to correlate the corrosion inhibition properties with the calculated quantum chemical parameters.

  16. Correlative analysis of the in situ changes of carrier decay and proton induced photoluminescence characteristics in chemical vapor deposition grown GaN

    Energy Technology Data Exchange (ETDEWEB)

    Gaubas, E., E-mail: eugenijus.gaubas@ff.vu.lt; Ceponis, T.; Jasiunas, A.; Meskauskaite, D.; Pavlov, J.; Tekorius, A.; Vaitkus, J. [Vilnius University, Institute of Applied Research, Vilnius LT-10222 (Lithuania); Kovalevskij, V.; Remeikis, V. [Centre for Physical Sciences and Technology, Vilnius LT-02300 (Lithuania)

    2014-02-10

    In order to evaluate carrier densities created by 1.6 MeV protons and to trace radiation damage of the 2.5 μm thick GaN epi-layers grown by metalorganic chemical vapor deposition technique, a correlation between the photoconductivity transients and the steady-state photoluminescence spectra have been examined. Comparison of luminescence spectra induced by proton beam and by laser pulse enabled us to evaluate the efficiency of a single proton generation being of 1 × 10{sup 7} cm{sup −3} per 1.6 MeV proton and 40 carrier pairs per micrometer of layer depth. This result indicates that GaN layers can be an efficient material for detection of particle flows. It has been demonstrated that GaN material can also be a rather efficient scintillating material within several wavelength ranges.

  17. Correlations in the chemical composition of rural background atmospheric aerosol in the UK determined in real time using time-of-flight mass spectrometry.

    Science.gov (United States)

    Beddows, David C S; Donovan, Robert J; Harrison, Roy M; Heal, Mathew R; Kinnersley, Robert P; King, Martin D; Nicholson, David H; Thompson, Katherine C

    2004-02-01

    An aerosol time-of-flight mass spectrometer (ATOFMS) was used to determine, in real time, the size and chemical composition of individual particles in the atmosphere at the remote inland site of Eskdalemuir, Scotland. A total of 51,980 particles, in the size range 0.3-7.4 microm, were detected between the 25th and 30th June 2001. Rapid changes in the number density, size and chemical composition of the atmospheric aerosol were observed. These changes are attributed to two distinct types of air mass; a polluted air mass that had passed over the British mainland before reaching Eskdalemuir, interposed between two cleaner air masses that had arrived directly from the sea. Such changes in the background aerosol could clearly be very important to studies of urban aerosols and attempts at source apportionment. The results of an objective method of data analysis are presented. Correlations were sought between the occurrence of: lithium, potassium, rubidium, caesium, beryllium, strontium, barium, ammonium, amines, nitrate, nitrite, boron, mercury, sulfate, phosphate, fluorine, chlorine, bromine, iodine and carbon (both elemental and organic hydrocarbon) in both fine (d 2.5 microm) particle fractions. Several previously unreported correlations were observed, for instance between the elements lithium, beryllium and boron. The results suggest that about 2 in 3 of all fine particles (by number rather than by mass), and 1 in 2 of all coarse particles containing carbon, consisted of elemental carbon rather than organic hydrocarbon (although a bias in the sensitivity of the ATOFMS could have affected these numbers). The ratio of the number of coarse particles containing nitrate anions to the number of particles containing chloride anions exceeded unity when the air mass had travelled over the British mainland. The analysis also illustrates that an air mass of marine origin that had travelled slowly over agricultural land can accumulate amines and ammonium.

  18. A Transition from Localized to Strongly Correlated Electron Behavior and Mixed Valence Driven by Physical or Chemical Pressure in ACo2As2 (A = Eu and Ca)

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Xiaoyan; Fabbris, Gilberto; Haskel, Daniel; Yaroslavtsev, Alexander A.; Cao, H.; Thompson, Corey M.; Kovnir, Kirill; Menushenkov, Alexey P.; Chernikov, Roman V.; Garlea, V. Ovidiu; Shatruk, Michael

    2016-03-02

    We demonstrate that the action of physical pressure, chemical compression, or aliovalent substitution in ACo(2)As(2) (A = Eu and Ca) has a general consequence of causing these antiferromagnetic materials to become ferromagnets. In all cases, the mixed valence triggered at the electropositive A site results in the increase of the Co 3d density of states at the Fermi level. Remarkably, the dramatic alteration of magnetic behavior results from the very minor (<0.15 eleetron) change in the population of the 3d orbitals. The mixed valence state of En observed in the high-pressure (HP) form of EuCo2As2 exhibits a remarkable stability, achieving the average oxidation state of +2.25 at 12.6 GPa. In the case of CaCo2As2, substituting even 10% of Eu or La into the Ca site causes ferromagnetic ordering of Co moments. Similar to HP-EuCo2As2, the itinerant 3d ferromagnetism emerges from electronic doping into the Co layer because of chemical compression of Eu sites in Ca0.9Eu0.1Co1.91As2 or direct electron doping in Ca0.85La0.15Co1.89As2. The results reported herein demonstrate the general possibility of amplifying minor localized electronic effects to achieve major changes in material's properties via involvement of strongly correlated electrons.

  19. Correlation between chemical composition and antibacterial activity of essential oils from fifteen Eucalyptus species growing in the Korbous and Jbel Abderrahman arboreta (North East Tunisia).

    Science.gov (United States)

    Elaissi, Ameur; Rouis, Zyed; Mabrouk, Samia; Salah, Karima Bel Haj; Aouni, Mahjoub; Khouja, Mohamed Larbi; Farhat, Farhat; Chemli, Rachid; Harzallah-Skhiri, Fethia

    2012-03-12

    The essential oils of fifteen Eucalyptus species harvested from the Jbel Abderrahman and Korbous arboreta (North East Tunisia) were screened for their antibacterial activities by the agar disc diffusion method. Eighteen major components as identified by GC/FID and GC/MS were selected for a study of the chemical and biological activity variability. The main one was 1,8-cineole, followed by spathulenol, trans-pinocarveol, α-pinene, p-cymene, globulol, cryptone, β-phellandrene, viridiflorol, borneol, limonene and isospathulenol. The chemical principal component analysis identified five species groups and subgroups, where each group constituted a chemotype, however that of the values of zone diameter of the inhibition (zdi) identified six groups of Eucalyptus oils, characterized by their antibacterial inhibition ability. The strongest activity was shown by E. platypus oil against Enterococcus faecalis and by E. lamannii oil against Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli. A correlation between the levels of some major components and the antibacterial activities was observed.

  20. Correlation Between Chemical Composition and Antibacterial Activity of Essential Oils from Fifteen Eucalyptus Species Growing in the Korbous and Jbel Abderrahman Arboreta (North East Tunisia

    Directory of Open Access Journals (Sweden)

    Fethia Harzallah-Skhiri

    2012-03-01

    Full Text Available The essential oils of fifteen Eucalyptus species harvested from the Jbel Abderrahman and Korbous arboreta (North East Tunisia were screened for their antibacterial activities by the agar disc diffusion method. Eighteen major components as identified by GC/FID and GC/MS were selected for a study of the chemical and biological activity variability. The main one was 1,8-cineole, followed by spathulenol, trans-pinocarveol, α-pinene, p-cymene, globulol, cryptone, β-phellandrene, viridiflorol, borneol, limonene and isospathulenol. The chemical principal component analysis identified five species groups and subgroups, where each group constituted a chemotype, however that of the values of zone diameter of the inhibition (zdi identified six groups of Eucalyptus oils, characterized by their antibacterial inhibition ability. The strongest activity was shown by E. platypus oil against Enterococcus faecalis and by E. lamannii oil against Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli. A correlation between the levels of some major components and the antibacterial activities was observed.

  1. Doping and bond length contributions to Mn K-edge shift in La1-SrMnO3 (=0-0.7) and their correlation with electrical transport properties

    Indian Academy of Sciences (India)

    S K Pandey; R Bindu; Ashwini Kumar; S Khalid; A V Pimpale

    2008-02-01

    The room temperature experimental Mn K-edge X-ray absorption spectra of La1-SrMnO3 ( = 0-0.7) are compared with the band structure calculations using spin polarized density functional theory. It is explicitly shown that the observed shift in the energy of Mn K-edge on substitution of divalent Sr on trivalent La sites corresponds to the shift in the center of gravity of the unoccupied Mn 4-band contributing to the Mn K-absorption edge region. This correspondence is then used to separate the doping and size contributions to the edge shift due to variation in the number of electrons in valence band and Mn-O bond lengths, respectively, when Sr is doped into LaMnO3. Such separation is helpful to find the localization behaviour of charge carriers and to understand the observed transport properties of these compounds.

  2. Physical and chemical parameter correlations with technical and technological characteristics of heating systems and the presence of Legionella spp. in the hot water supply.

    Science.gov (United States)

    Rakić, Anita; Štambuk-Giljanović, Nives

    2016-02-01

    The purpose of this study was to evaluate the prevalence of Legionella spp. and compare the quality of hot water between four facilities for accommodation located in Southern Croatia (the Split-Dalmatian County). The research included data collection on the technical and technological characteristics in the period from 2009 to 2012. The survey included a type of construction material for the distribution and internal networks, heating system water heater type, and water consumption. Changes in water quality were monitored by determination of the physical and chemical parameters (temperature, pH, free chlorine residual concentrations, iron, zinc, copper and manganese) in the samples, as well as the presence and concentration of bacteria Legionella spp. The temperature is an important factor for the development of biofilms, and it is in negative correlation with the appearance of Legionella spp. Positive correlations between the Fe and Zn concentrations and Legionella spp. were established, while the inhibitory effect of a higher Cu concentration on the Legionella spp. concentration was proven. Legionella spp. were identified in 38/126 (30.2%) of the water samples from the heating system with zinc-coated pipes, as well as in 78/299 (26.1%) of the samples from systems with plastic pipes. A similar number of Legionella spp. positive samples were established regardless of the type of the water heating system (central or independent). The study confirms the necessity of regular microbial contamination monitoring of the drinking water distribution systems (DWDSs).

  3. 化学位移 MRI 测量2型糖尿病患者胰腺脂肪含量的临床研究%Study of pancreatic steatosis in patients with type 2 diabetes by chemical shift magnetic resonance imaging

    Institute of Scientific and Technical Information of China (English)

    柴军; 刘朋; 洪旭; 尹洁; 于恒池; 苏天昊; 张洁; 史凯宁; 靳二虎

    2015-01-01

    Objective To investigate the fat content and distribution of the pancreas,and to explore its relation with hepatic fat content by chemical shift MRI in patients with newly - diagnosed type 2 diabetes. Methods 70 patients with newly - diagnosed type 2 diabetes were recrui-ted in this study. Fat content in the pancreatic head,body,tail and the liver was respectively measured with the technique of double - echo chemi-cal shift gradient - echo magnetic resonance imaging. The fat fraction in the pancreatic head,body and tail was compared. Its relation with hepatic fat fraction was analyzed. Results The fat fraction in the pancreatic head,body and tail was 5. 59% ± 4. 70% ,4. 80% ± 3. 75% and 4. 88% ± 3. 86% ,respectively,and there was no statistical difference among them( F = 1. 761,P ﹥ 0. 05). The mean value of fat fraction in the pancreas and the liver was 5. 15% ± 3. 75% and 9. 88% ± 3. 19% ,respectively. They were not correlated each other( r = 0. 053,P ﹥ 0. 05). Conclu-sion Fat content in the head,body and tail of the pancreas was basically even. And the pancreatic and hepatic fat content was not correlated in patients with newly - diagnosed type 2 diabetes.%目的:采用化学位移 MRI 研究初诊2型糖尿病患者的胰腺脂肪含量及分布特点,并探讨胰腺与肝脏脂肪含量的相关性。方法征集初诊的2型糖尿病患者70例,采用化学位移双回波 MRI 技术分别测量胰腺头部、体部、尾部及肝脏的脂肪含量,比较胰腺头部、体部、尾部的脂肪含量差异,分析胰腺脂肪含量与肝脏脂肪含量的相关性。结果本组患者胰腺头部、体部、尾部的脂肪分数分别为5.59%±4.70%、4.80%±3.75%、4.88%±3.86%,三个区域的脂肪含量没有统计学差异( F =1.761,P ﹥0.05)。胰腺的平均脂肪分数为5.15%±3.75%,肝脏为9.88%±3.19%,胰腺的脂肪含量与肝脏的脂肪含量没有相关性( r =0.053,P ﹥0.05

  4. Implementing OpenShift

    CERN Document Server

    Miller, Adam

    2013-01-01

    A standard tutorial-based approach to using OpenShift and deploying custom or pre-built web applications to the OpenShift Online cloud.This book is for software developers and DevOps alike who are interested in learning how to use the OpenShift Platform-as-a-Service for developing and deploying applications, how the environment works on the back end, and how to deploy their very own open source Platform-as-a-Service based on the upstream OpenShift Origin project.

  5. Quantized beam shifts

    CERN Document Server

    Kort-Kamp, W J M; Dalvit, D A R

    2015-01-01

    We predict quantized Imbert-Fedorov, Goos-H\\"anchen, and photonic spin Hall shifts for light beams impinging on a graphene-on-substrate system in an external magnetic field. In the quantum Hall regime the Imbert-Fedorov and photonic spin Hall shifts are quantized in integer multiples of the fine structure constant $\\alpha$, while the Goos- H\\"anchen ones in multiples of $\\alpha^2$. We investigate the influence on these shifts of magnetic field, temperature, and material dispersion and dissipation. An experimental demonstration of quantized beam shifts could be achieved at terahertz frequencies for moderate values of the magnetic field.

  6. Concentrations, correlations and chemical species of PM2.5/PM10 based on published data in China: Potential implications for the revised particulate standard.

    Science.gov (United States)

    Zhou, Xuehua; Cao, Zhaoyu; Ma, Yujie; Wang, Linpeng; Wu, Ruidong; Wang, Wenxing

    2016-02-01

    Particulate matter (PM) has been of great concern in China due to the increasing haze pollution in recent years. In 2012, the Chinese national ambient air quality standard (NAAQS) was amended with a "more strict" regulation on the PM concentrations, i.e., 35 and 70 µg/m(3) for annual PM2.5 and PM10 averages, respectively (Grade-Ⅱ, GB3095-2012). To evaluate the potential of China to attain such new NAAQS and provide a more generalized chemical profile of PM in China, a comprehensive statistical analysis was carried out based on the published data of parallel PM2.5 and PM10 mass concentrations and chemical compositions of PM2.5 and PM10. The results show that most of the measured concentrations far exceed the new NAAQS. PM2.5 and PM10 show a strong positive correlation (R(2) = 0.87, p China. Organic carbon (OC), sulfate and crustal species are the three major components of PM. The NO3(-)/SO4(2-) ratios are 0.43 ± 0.26 in PM2.5 and 0.56 ± 0.29 in PM10, and the OC/EC ratios are 3.63 ± 1.73 in PM2.5 and 4.17 ± 2.09 in PM10, signifying that the stationary emissions from coal combustion remain the main PM source. An evaluation of PM2.5 situation in current China was carried out and the results show that it would take about 27 years to meet the limit value of 35 µg/m(3) in the revised standard, implying a rigorous challenge in PM2.5 control in China in the future.

  7. Making Shifts toward Proficiency

    Science.gov (United States)

    McGatha, Maggie B.; Bay-Williams, Jennifer M.

    2013-01-01

    The Leading for Mathematical Proficiency (LMP) Framework (Bay-Williams et al.) has three components: (1) The Standards for Mathematical Practice; (2) Shifts in classroom practice; and (3) Teaching skills. This article briefly describes each component of the LMP framework and then focuses more in depth on the second component, the shifts in…

  8. Shifting employment revisited

    NARCIS (Netherlands)

    Cremers, Jan; Gramuglia, Alessia

    2014-01-01

    The CLR-network examined in 2006 the phenomenon of undeclared labour, with specific regard to the construction sector. The resulting study, Shifting Employment: undeclared labour in construction (Shifting-study hereafter), gave evidence that this is an area particularly affected by undeclared activi

  9. Shifted Independent Component Analysis

    DEFF Research Database (Denmark)

    Mørup, Morten; Madsen, Kristoffer Hougaard; Hansen, Lars Kai

    2007-01-01

    Delayed mixing is a problem of theoretical interest and practical importance, e.g., in speech processing, bio-medical signal analysis and financial data modelling. Most previous analyses have been based on models with integer shifts, i.e., shifts by a number of samples, and have often been carried...

  10. OpenShift cookbook

    CERN Document Server

    Gulati, Shekhar

    2014-01-01

    If you are a web application developer who wants to use the OpenShift platform to host your next big idea but are looking for guidance on how to achieve this, then this book is the first step you need to take. This is a very accessible cookbook where no previous knowledge of OpenShift is needed.

  11. Externally predictive single-descriptor based QSPRs for physico-chemical properties of polychlorinated-naphthalenes: Exploring relationships of log S{sub W}, log K{sub OA}, and log K{sub OW} with electron-correlation

    Energy Technology Data Exchange (ETDEWEB)

    Chayawan; Vikas, E-mail: qlabspu@pu.ac.in

    2015-10-15

    Highlights: • Aqueous solubility and partition coefficient are modelled using single-parameter. • Electron-correlation observed as a vital predictorof physico-chemical properties. • For octanol-air partition coefficient, energy and polarizability yield best models. • Dipole-moment is found to be worst single-descriptor for the properties analysed. - Abstract: Quantitative structure–property relationships (QSPRs), based only on a single-parameter, are proposed for the prediction of physico-chemical properties, namely, aqueous solubility (log S{sub W}), octanol–water partition coefficient (log K{sub OW}) and octanol–air partition coefficient (log K{sub OA}) of polychloronaphthalenes (PCNs) including all the 75 chloronaphthalene congeners. The QSPR models are developed using molecular descriptors computed through quantum mechanical methods including ab-initio as well as advanced semi-empirical methods. The predictivity of the developed models is tested through state-of-the-art external validation procedures employing an external prediction set of compounds. To analyse the role of instantaneous interactions between electrons (the electron-correlation), the models are also compared with those developed using only the electron-correlation contribution of the quantum chemical descriptor. The electron-correlation contribution towards the chemical hardness and the LUMO energy are observed to be the best predictors for octanol–water partition coefficient, whereas for the octanol–air partition coefficient, the total electronic energy and electron-correlation energy are found to be reliable descriptors, in fact, even better than the polarisability. For aqueous solubility of PCNs, the absolute electronegativity is observed to be the best predictor. This work suggests that the electron-correlation contribution of a quantum-chemical descriptor can be used as a reliable indicator for physico-chemical properties, particularly the partition coefficients.

  12. Correlation of chromosome patterns in human leukemic cells with exposure to chemicals and/or radiation. Comprehensive progress report, July 1991--June 1994

    Energy Technology Data Exchange (ETDEWEB)

    Rowley, J.D.

    1994-06-01

    This comprehensive progress report provides a synopsis of major research accomplishments during the years of 1991-1994, including the technical aspects of the project. The objectives and accomplishments are as follows: 1. Defining the chromosome segments associated with radiation and chemically-induced leukemogenesis (treatment-related acute myeloid leukemia, t-AML); A. Continued genetic analysis of chromosomes 5 and 7, B. Correlation of treatment with balanced and unbalanced translocations. 2. Cloning the breakpoints in balanced translocations in t-AML; A. Clone the t(9;11) and t(11;19) breakpoints, B. Clone the t(3,21)(q26,q22) breakpoint, C. Determine the relationship of these translocations to prior exposure to topoisomerase II inhibitors. 3. Compare the breakpoint junctions in patients who have the same translocations in t-AML and AML de novo. 4. Map the scaffold attachment regions in the genes that are involved in balanced translocations in t-AML. Plans for the continuation of present objectives and possible new objectives in consideration of past results are also provided.

  13. The Correlation between Chemical Composition, as Determined by UPLC-TOF-MS, and Acute Toxicity of Veratrum nigrum L. and Radix paeoniae alba

    Directory of Open Access Journals (Sweden)

    Xianxie Zhang

    2014-01-01

    Full Text Available The eighteen incompatible medicaments is an important theory in traditional Chinese medicine. The theory suggests that drugs in the eighteen incompatible medicaments can be toxic when used together. Veratrum nigrum L. and Radix paeoniae alba belong to the eighteen incompatible medicaments and have been prohibited for thousands of years. This study offers preliminary insight into the mechanism and chemical constituents responsible for the incompatibility and toxicity of these two agents. Specifically, we performed toxicology studies to identify and quantify the constituent substances of the two agents. Experiments revealed that acute toxicity increases when the dose of V. nigrum L. is higher than, or equal to, RPA. UPLC-TOF-MS analysis showed that, although the volumes of V. nigrum L. were the same, the content of some veratrum alkaloids changed significantly and had a trend toward a highly positive correlation r≥0.8 with toxicity. This suggests that the increased toxicity of the V. nigrum L. and RPA combination was due mainly to increased content of the special veratrum alkaloids. The cytotoxicity of veratridine in SH-SY5Y cells was decreased with increasing paeoniflorin concentrations. This study provides insight into the mechanism behind the incompatibility theory of TCM.

  14. Photoluminescence characteristics of CdS layers deposited in a chemical bath and their correlation to CdS/CdTe solar cell performance

    Energy Technology Data Exchange (ETDEWEB)

    Mendoza-Perez, R.; Aguilar-Hernandez, J.; Sastre-Hernandez, J.; Ximello-Quiebras, N.; Contreras-Puente, G.; Vigil-Galan, O.; Moreno-Garcia, E. [Escuela Superior de Fisica y Matematicas del IPN, Edificio 9, UPALM, DF 07738 (Mexico); Santana-Rodriguez, G. [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Coyoacan 04510, DF (Mexico); Morales-Acevedo, A. [CINVESTAV-IPN, Depto. de Ingenieria Electrica, Avenida IPN No. 2508, DF 07360 (Mexico)

    2006-06-15

    In this work, we study CdS films processed by chemical bath deposition (CBD) using different thiourea concentrations in the bath solution with post-thermal treatments using CdCl{sub 2}. We study the effects of the thiourea concentration on the photovoltaic performance of the CdS/CdTe solar cells, by the analysis of the I-V curve, for S/Cd ratios in the CBD solution from 3 to 8. In this range of S/Cd ratios the CdS/CdTe solar cells show variations of the open circuit voltage (V{sub oc}), the short circuit current (J{sub sc}) and the fill factor (FF). Other experimental data such as the optical transmittance and photoluminescence were obtained in order to correlate to the I-V characteristics of the solar cells. The best performance of CdS-CdTe solar cells made with CdS films obtained with a S/Cd ratio of 6 is explained in terms of the sulfur vacancies to sulfur interstitials ratio in the CBD-CdS layers. (author)

  15. NMR cross-correlated relaxation rates reveal ion coordination sites in DNA

    NARCIS (Netherlands)

    Fiala, R.; Spackova, N.; Foldynová-Trantírková, S.; Sponer, J.; Sklenár, V.; Trantirek, L.

    2011-01-01

    In this work, a novel NMR method for the identification of preferential coordination sites between physiologically relevant counterions and nucleic acid bases is demonstrated. In this approach, the NMR cross-correlated relaxation rates between the aromatic carbon chemical shift anisotropy and the pr

  16. Protein structure prediction using global optimization by basin-hopping with NMR shift restraints.

    Science.gov (United States)

    Hoffmann, Falk; Strodel, Birgit

    2013-01-14

    Computational methods that utilize chemical shifts to produce protein structures at atomic resolution have recently been introduced. In the current work, we exploit chemical shifts by combining the basin-hopping approach to global optimization with chemical shift restraints using a penalty function. For three peptides, we demonstrate that this approach allows us to find near-native structures from fully extended structures within 10,000 basin-hopping steps. The effect of adding chemical shift restraints is that the α and β secondary structure elements form within 1000 basin-hopping steps, after which the orientation of the secondary structure elements, which produces the tertiary contacts, is driven by the underlying protein force field. We further show that our chemical shift-restraint BH approach also works for incomplete chemical shift assignments, where the information from only one chemical shift type is considered. For the proper implementation of chemical shift restraints in the basin-hopping approach, we determined the optimal weight of the chemical shift penalty energy with respect to the CHARMM force field in conjunction with the FACTS solvation model employed in this study. In order to speed up the local energy minimization procedure, we developed a function, which continuously decreases the width of the chemical shift penalty function as the minimization progresses. We conclude that the basin-hopping approach with chemical shift restraints is a promising method for protein structure prediction.

  17. 河北省食管癌与土壤化学元素的关系%Correlation Between Chemical Elements in Soil and Esophageal Cancer in Hebei

    Institute of Scientific and Technical Information of China (English)

    赵树青; 张秀兰; 赵川; 陈志峰; 杨立学; 任永红; 梁索源

    2011-01-01

    目的 从土壤化学元素含量分布规律,探索河北省食管癌死亡率地域性分布与化学元素的关系,为食管癌的防治提供科学依据.方法 根据研究区域,2008-06采用网络布点,常规采集土壤样品(磁县-食管癌高发区、赤城-食管癌低发区,各采集31份),测定土壤中铜、锌、铁、钙、镁元素含量,对磁县土壤成分差别较大的元素铜、锌、铁、镁的含量与磁县食管癌死亡率进行了Pearson直线相关分析.结果 磁县土壤中铜的含量均值为12.68μg/g、锌为119.70 μg/g,均明显高于赤城的12.07μg/g、55.33μg/g,铁、镁含量、铜/锌比值为443.98μg/g、1526.12μg/g、0.12分别低于赤城的7841.48μg/g、2202.93μg/g、0.22,经t检验,差异均有统计学意义(P0.05),差异无统计学意义.食管癌死亡率与土壤中的铜、锌、铁、镁含量有相关性.铜、锌的含量与食管癌死亡率呈正相关,相关系数分别为r=0.308 8(P<0.05)、r=0.254 8(p<0.05);铁、镁的含量呈负相关,相关系数分别为r=-0.267 9,(P<0.05)、r=-0.342 8,(P<0.05).结论 河北省食管癌死亡率地域性分布与土壤化学元素含量有关,提示地质条件的差异可能是河北省食管癌死亡率具有明显地域性的原因之一.%Objective To understand chemical elements concentrations in soil, analyze the correlation between the chemical elements in soil and the distribution of esophageal cancer mortality in Hebei province and provide scientific evidence for the prevention and control of the disease. Methods Sixty two soil samples were collected in highly endemic area-Cixian county (31) and low endemic area-Chicheng county (31) to detect the copper,zinc , iron, calcium and magnesium concentrations. Pearson liner correlation analysis was conducted on the correlation between high concentration of copper, zinc, iron and magnesium in Cixian and the mortality of esophageal cancer. Results The results showed that the copper and zinc

  18. Shift Verification and Validation

    Energy Technology Data Exchange (ETDEWEB)

    Pandya, Tara M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Evans, Thomas M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Davidson, Gregory G [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Johnson, Seth R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Godfrey, Andrew T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-09-07

    This documentation outlines the verification and validation of Shift for the Consortium for Advanced Simulation of Light Water Reactors (CASL). Five main types of problems were used for validation: small criticality benchmark problems; full-core reactor benchmarks for light water reactors; fixed-source coupled neutron-photon dosimetry benchmarks; depletion/burnup benchmarks; and full-core reactor performance benchmarks. We compared Shift results to measured data and other simulated Monte Carlo radiation transport code results, and found very good agreement in a variety of comparison measures. These include prediction of critical eigenvalue, radial and axial pin power distributions, rod worth, leakage spectra, and nuclide inventories over a burn cycle. Based on this validation of Shift, we are confident in Shift to provide reference results for CASL benchmarking.

  19. Shift Verification and Validation

    Energy Technology Data Exchange (ETDEWEB)

    Pandya, Tara M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Evans, Thomas M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Davidson, Gregory G [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Johnson, Seth R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Godfrey, Andrew T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-09-07

    This documentation outlines the verification and validation of Shift for the Consortium for Advanced Simulation of LightWater Reactors (CASL). Fivemain types of problems were used for validation: small criticality benchmark problems; full-core reactor benchmarks for light water reactors; fixed source coupled neutron-photon dosimetry benchmarks; depletion/burnup benchmarks; and full-core reactor performance benchmarks. We compared Shift results to measured data and other simulated Monte Carlo radiation transport code results and found very good agreement in a variety of comparison measures. These include prediction of critical eigenvalue, radial and axial pin power distributions, rod worth, leakage spectra, and nuclide inventories over a burn cycle. Based on this validation of Shift, we are confident in Shift to provide reference results for CASL benchmarking.

  20. Trends in adsorbate induced core level shifts

    Science.gov (United States)

    Nilsson, Viktor; Van den Bossche, Maxime; Hellman, Anders; Grönbeck, Henrik

    2015-10-01

    Photoelectron core level spectroscopy is commonly used to monitor atomic and molecular adsorption on metal surfaces. As changes in the electron binding energies are convoluted measures with different origins, calculations are often used to facilitate the decoding of experimental signatures. The interpretation could in this sense benefit from knowledge on trends in surface core level shifts for different metals and adsorbates. Here, density functional theory calculations have been used to systematically evaluate core level shifts for (111) and (100) surfaces of 3d, 4d, and 5d transition metals upon CO, H, O and S adsorption. The results reveal trends and several non-intuitive cases. Moreover, the difficulties correlating core level shifts with charging and d-band shifts are underlined.

  1. E-2-Benzylidenebenzocycloalkanones. IV. Studies on transmission of substituent effects on 13C NMR chemical shifts of E-2-(X-benzylidene)-1-tetralones, and -benzosuberones. Comparison with the 13C NMR data of chalcones and E-2-(X-benzylidene)-1-indanones

    Science.gov (United States)

    Perjési, Pál; Linnanto, Juha; Kolehmainen, Erkki; Ősz, Erzsébet; Virtanen, Elina

    2005-04-01

    Single substituent parameter (SSP) and dual substituent parameter (DSP) analyses were applied to study the transmission of substituent effects on selected 13C NMR chemical shifts of the cyclic chalcone analogues, E-2-(4'-X-benzylidene)-1-tetralones ( 2) and E-2-(4'-X-benzylidene)-1-benzosuberones ( 3). In order to study how the geometry of the cyclic chalcone analogues affects the transmission of substituent effects similar investigations with the respective chalcones ( 4) were also performed. The results obtained earlier with the five-membered analogue E-2-(4'-X-benzylidene)-1-indanones ( 1) were also involved in the comparisons. Geometry optimization of the unsubstituted 1a, 2a, 3a and 4a as well as the substituted 2 and 3 was performed by ab initio quantum chemical calculations. Both SSP and DSP analyses reflected that resonance effects contribute more to the chemical shift of C-α (C2), while inductive effects primarily affect that of C-β (C10) of the enone moiety of all the four series. This latter effect, however, is far not as pronounced as that of the former one. It was found that DSP analysis data ( ρF and ρR values) of transmission of substituent effects on the δC2 data can serve as a measure of choice to study the conformation (planarity) of the investigated enones in the four series.

  2. Quantification of fat using chemical shift imaging and 1H-MR spectroscopy in phantom model%化学位移成像及MR波谱分析在体外水脂模型中对脂肪定量的研究

    Institute of Scientific and Technical Information of China (English)

    彭新桂; 居胜红; 方芳; 滕皋军

    2010-01-01

    Objective To evaluate the accuracy of chemical shift imaging (CSI) and MR spectroscopy (MRS) for fat quantification in phantom model. Methods Eleven phantoms were made according to the volume percentage of fat ranging from 0 to 100% with an interval of 10% . The fat concentration in the phantoms were measured respectively by CSI and MRS and compared using one-sample t test The correlation between the two methods was also analyzed. The concentration of saturated fatty acids ( FS), unsaturated fatty acids (FU) and the polyunsaturation degree (PUD) were calculated by using MRS. Results The fat concentration was (48.0 ±1.0)%, (57.0 ±0.5)%, (67.3±0.6)%, (77.3 ±0.6)%, (83.3±0.6)% and (91.0±1.0)% respectively with fat volume of 50% to 100% by CSI. The fat concentration was (8.3 ±0.6)%, (16.3 ±0.7)%, (27.7 ±0.6)%, (36.0 ±1.0)%, (43.5±0. 6)% and (56. 5 ±1. 0)% respectively with fat volume of 10% to 60% by MRS, the fat concentration were underestimated by CSI and MRS (P < 0.05 ), and had high linear correlation with the real concentration in phantoms ( CSI: r = 0. 998, MRS: r = 0.996, P < 0.01 ) . There was also a linear correlation between two methods (r = 0. 992, P < 0. 01 ) but no statistically significant difference ( pairedsamples t test, t = -0. 125 ,P = 0.903). By using MRS, the relative ratio of FS and FU in fat were 0. 15and 0. 85, the PUD was 0. 0325, respectively, and highly consistent with these in phantoms. Conclusion Both CSI and MRS are efficient and accurate methods in fat quantification at 7.0 T MR.%目的 评价化学位移成像(chemical shift imaging,CSI)和MRS两种方法在脂肪研究中的作用,为进一步活体实验提供定量标准.方法 在7.0 T MR成像仪上运用CSI和MRS方法对体外水脂模型进行水脂定量分析.体外水脂模型的脂肪含量从0~100%平均分成11个组,各组间浓度相差10%,分别应用水、脂肪选择性CSI和1H-MRS对体外水脂模型进行图像和波谱数据采集,对2种方法所得

  3. Correlation Analysis of the Power Team Management Thinking Paradigm Shift%对电力班组管理思维模式转变的相关分析

    Institute of Scientific and Technical Information of China (English)

    李婷婷

    2015-01-01

    The team is the most basic level of power supply enterprise unit, is the basis of the power supply enterprise management, team building and management of a direct impact on the development of the power companies. Power supply enterprises with particularity and rigor for the construction and management team with high demands. Presented to the power supply enterprise team management thinking paradigm shift specific recommendations designed to power the production of new construction and management team to provide a reference.%班组是供电企业中最基层的单位,是供电企业管理的基础,班组的建设和管理水平直接影响着供电企业的发展。供电企业具有的特殊性和严谨性对班组的建设和管理有着很高的要求。提出了对供电企业班组管理思维模式转变具体的建议,旨在为电力生产的新型班组建设和管理提供参考。

  4. QSAR model for human pregnane X receptor (PXR) binding: Screening of environmental chemicals and correlations with genotoxicity, endocrine disruption and teratogenicity

    DEFF Research Database (Denmark)

    Dybdahl, Marianne; Nikolov, Nikolai G.; Wedebye, Eva Bay;

    2012-01-01

    among chemicals predicted to cause adverse effects, such as genotoxicity, teratogenicity, estrogen receptor activation and androgen receptor antagonism compared to chemicals not causing these effects. The developed model may be useful as a tool for predicting potential PXR ligands and for providing...

  5. A Shift of Power

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Administrative reforms are shifting prefecture government powers to the county level in an effort to boost local economies on July 8, the government of China’s southernmost Hainan Province announced that it was to hand over 177 of its administrative powers to county-level governments. The move practically dismantled the powers of the

  6. On an accidental degeneracy in the {sup 31}P{l_brace}{sup 1}H{r_brace} NMR chemical shifts in ruthenium diphosphine complexes; Sobre uma degenerescencia acidental nos deslocamentos quimicos de RMN {sup 31}P{l_brace}{sup 1}H{r_brace} em complexos difosfinicos de rutenio

    Energy Technology Data Exchange (ETDEWEB)

    Valle, Eliana Maira Agostini; Nascimento, Fabio Batista do; Ferreira, Antonio Gilberto; Batista, Alzir A. [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil). Dept. de Quimica]. E-mail: alzir@dq.ufscar.br; Monteiro, Marcos Claudio Rodrigues; Machado, Sergio de Paula [Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ (Brazil). Inst. de Quimica. Dept. de Quimica Inorganica; Ellena, Javier; Castellano, Eduardo E.; Azevedo, Eduardo Ribeiro de [Universidade de Sao Paulo (USP), Sao Carlos, SP (Brazil). Inst. de Fisica

    2008-07-01

    The [RuCl(bipy)(dppb)(4-pic)]PF{sub 6} complex was prepared and fully characterized. The X-ray crystal structure of this complex was determined in order to make an unambiguous distinction between the two possible positions of the 4-methylpyridine ligand (4-pic) in the compound: trans to phosphorus atom or trans to nitrogen atom. The [RuCl(bipy)(dppb)(4-pic)]PF{sub 6} complex exhibits an unusual temperature-dependent accidental degeneracy of the {sup 31}P chemical shifts in its solution NMR spectrum. (author)

  7. Label-free surface-enhanced infrared spectro-electro-chemical analysis of the Redox potential shift of cytochrome c complexed with a cardiolipin-containing lipid membrane of varied composition

    Science.gov (United States)

    Liu, Li; Wu, Lie; Zeng, Li; Jiang, Xiu-E.

    2015-12-01

    In this study, a lipid membrane was fabricated by fusing cardiolipin-phosphatidylcholine (CL_PC, 1:4) vesicles onto a hydrophobic surface of 1-dodecanethiol (DT) preadsorbed on a nanostructured gold film. By changing the concentration of the DT adsorption solution, we constructed a series of CL_PC-DT bilayers with different hydrophobicity to study the effects of lipid membrane characteristics on the adsorption conformation of cytochrome c (Cyt c). Electrochemical analysis showed that the formal potential is 0.24 V for Cyt c-CL_PC-DT(10), 0.2 V for Cyt c-CL_PC-DT(20), and 0.16 V for Cyt c-CL_PC-DT(40) — a gradual positive shift with the decreasing DT concentration — relative to the potential of native cyt c (0.02 V). Potential-induced surface-enhanced infrared adsorption difference spectroscopy revealed that the gradual positive shift of the formal potential of CL-bound cyt c is determined by the environment with the gradually lowered dielectric constant for the heme cofactor in CL-bound cyt c (Fe3+). Project supported by the National Natural Science Foundation of China (Grant Nos. 91227114, 21322510, and 21105097), the China Postdoctoral Science Foundation (Grant No. 2013M530998), the Natural Science Foundation of Jilin Province, China (Grant No. 201215092), and the President Funds of the Chinese Academy of Sciences.

  8. A New Paradigm for Chemical Engineering?

    DEFF Research Database (Denmark)

    Gani, Rafiqul

    businesses has been observed. There is an increasing trend within the chemical industry to focus on products and the sustainable processes that can make them. Do these changes point to a paradigm shift in chemical engineering as a discipline? Historically, two previous paradigm shifts in chemical engineering...... corresponded to major shifts in chemical engineering as a discipline, which affected not only the education of chemical engineers, but also the development of chemical engineering as a discipline. Has the time come for a new paradigm shift that will prepare the current and future chemical engineering graduates...... to tackle the complex problems facing the chemicals based industries and serve the modern society more efficiently? The lecture will review the current status of chemical engineering as a discipline, the proposals for the third paradigm, the need for such a paradigm shift and related educational issues....

  9. Development of a drug-in-adhesive patch combining ion pair and chemical enhancer strategy for transdermal delivery of zaltoprofen: pharmacokinetic, pharmacodynamic and in vitro/in vivo correlation evaluation.

    Science.gov (United States)

    Cui, Hongxia; Quan, Peng; Zhou, Zhuang; Fang, Liang

    2016-11-01

    The aim of the study was to develop a drug-in-adhesive patch system for transdermal delivery of zaltoprofen (ZAL). The formulation was designed in combination with the ion pair and chemical enhancer strategy. Seven organic amines were chosen as counter ions, and the prepared ion pairs were characterized by Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The in vivo pharmacokinetic performance of ZAL was studied on rabbits following transdermal and intravenous administration. A deconvolution method was applied to determine the correlation between the in vitro permeation and the in vivo absorption. Acetic acid-induced writhing response was conducted on mice to evaluate the analgesic effect. In vitro permeation results showed that both ion pairs and chemical enhancers were effective in modulating ZAL skin permeation from patches. The enhancement ratio was negatively correlated to the polar surface area (PSA) of counter ions, and was positively correlated to the octanol-water partition coefficient (log Ko/w) of chemical enhancers, respectively. The optimized formulation contained 10% (w/w) ZAL-triethylamine and 10% (w/w) isopropyl myristate, with DURO-TAK® 87-4098 as the pressure sensitive adhesive matrix. Furthermore, the in vitro permeation data were well correlated with the in vivo absorption data. The analgesic effect of the optimized patch was comparable to the commercial indometacin plasters. In conclusion, it was feasible for transdermal delivery of ZAL by the synergistic action of ion pair and chemical enhancer, and the in vitro permeation data were indicative of the in vivo performance for the developed patches.

  10. On the Lamb shift

    Energy Technology Data Exchange (ETDEWEB)

    Villarroel, D. [Av. Tobalaba 3696, Puente Alto, Santiago, Metropolitana (Chile)

    2008-02-15

    The Lamb shift is calculated, in an approximate way, considering the hydrogen atom as an isolated physical system; the quantized radiation field does not play any role in the present approach. Our formalism is based on the generalization of the Dirac wave equation that incorporates the effects of the electron self-fields directly into it. Both the physical picture as well as the mathematical formalism have their roots in the classical theory of the electron. (author)

  11. Correlation spectrometer

    Science.gov (United States)

    Sinclair, Michael B.; Pfeifer, Kent B.; Flemming, Jeb H.; Jones, Gary D.; Tigges, Chris P.

    2010-04-13

    A correlation spectrometer can detect a large number of gaseous compounds, or chemical species, with a species-specific mask wheel. In this mode, the spectrometer is optimized for the direct measurement of individual target compounds. Additionally, the spectrometer can measure the transmission spectrum from a given sample of gas. In this mode, infrared light is passed through a gas sample and the infrared transmission signature of the gasses present is recorded and measured using Hadamard encoding techniques. The spectrometer can detect the transmission or emission spectra in any system where multiple species are present in a generally known volume.

  12. QSAR model for human pregnane X receptor (PXR) binding: Screening of environmental chemicals and correlations with genotoxicity, endocrine disruption and teratogenicity

    Energy Technology Data Exchange (ETDEWEB)

    Dybdahl, Marianne, E-mail: mdyb@food.dtu.dk; Nikolov, Nikolai G.; Wedebye, Eva Bay; Jónsdóttir, Svava Ósk; Niemelä, Jay R.

    2012-08-01

    The pregnane X receptor (PXR) has a key role in regulating the metabolism and transport of structurally diverse endogenous and exogenous compounds. Activation of PXR has the potential to initiate adverse effects, causing drug–drug interactions, and perturbing normal physiological functions. Therefore, identification of PXR ligands would be valuable information for pharmaceutical and toxicological research. In the present study, we developed a quantitative structure–activity relationship (QSAR) model for the identification of PXR ligands using data based on a human PXR binding assay. A total of 631 molecules, representing a variety of chemical structures, constituted the training set of the model. Cross-validation of the model showed a sensitivity of 82%, a specificity of 85%, and a concordance of 84%. The developed model provided knowledge about molecular descriptors that may influence the binding of molecules to PXR. The model was used to screen a large inventory of environmental chemicals, of which 47% was found to be within domain of the model. Approximately 35% of the chemicals within domain were predicted to be PXR ligands. The predicted PXR ligands were found to be overrepresented among chemicals predicted to cause adverse effects, such as genotoxicity, teratogenicity, estrogen receptor activation and androgen receptor antagonism compared to chemicals not causing these effects. The developed model may be useful as a tool for predicting potential PXR ligands and for providing mechanistic information of toxic effects of chemicals. -- Highlights: ► Global QSAR model for the identification of PXR ligands was developed. ► Molecular descriptors that may influence PXR binding were identified. ► 35% of a large set of environmental chemicals were predicted to be PXR ligands. ► Predicted PXR binding was associated with various adverse effects.

  13. Quantum Key Distribution Network Based on Differential Phase Shift

    Institute of Scientific and Technical Information of China (English)

    WANG Wan-Ying; WANG Chuan; WEN Kai; LONG Gui-Lu

    2007-01-01

    Using a series of quantum correlated photon pairs, we propose a theoretical scheme for any-to-any multi-user quantum key distribution network based on differential phase shift. The differential phase shift and the different detection time slots ensure the security of our scheme against eavesdropping. We discuss the security under the intercept-resend attack and the source replacement attack.

  14. Inspection of chemically roughened copper surfaces using optical interferometry and scanning electron microscopy: Establishing a correlation between surface morphology and solderability

    Energy Technology Data Exchange (ETDEWEB)

    Stevenson, J.O.; Hosking, F.M.; Guilinger, T.R.; Yost, F.G.; Sorensen, N.R.

    1995-08-01

    Sandia National Laboratories has established a Cooperative Research and Development Agreement with consortium members of the National Center for Manufacturing Sciences (NCMS) to develop fundamental generic technology in printed wiring board materials and surface finishes. We are investigating the effects of surface roughness on the wettability and solderability behavior of several types of copper board finishes to gain insight into surface morphologies that lead to improved solderability. In this paper, we present optical interterometry and scanning electron microscopy results for a variety of chemically-etched copper substrates. Initial testing on six chemical etches demonstrate that surface roughness can be greatly enhanced through chemical etching. Noticeable movements in solder wettability were observed to company increases in roughness.

  15. Catastrophic shifts in ecosystems

    Science.gov (United States)

    Scheffer, Marten; Carpenter, Steve; Foley, Jonathan A.; Folke, Carl; Walker, Brian

    2001-10-01

    All ecosystems are exposed to gradual changes in climate, nutrient loading, habitat fragmentation or biotic exploitation. Nature is usually assumed to respond to gradual change in a smooth way. However, studies on lakes, coral reefs, oceans, forests and arid lands have shown that smooth change can be interrupted by sudden drastic switches to a contrasting state. Although diverse events can trigger such shifts, recent studies show that a loss of resilience usually paves the way for a switch to an alternative state. This suggests that strategies for sustainable management of such ecosystems should focus on maintaining resilience.

  16. Correlation of rocket propulsion fuel properties with chemical composition using comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry followed by partial least squares regression analysis.

    Science.gov (United States)

    Kehimkar, Benjamin; Hoggard, Jamin C; Marney, Luke C; Billingsley, Matthew C; Fraga, Carlos G; Bruno, Thomas J; Synovec, Robert E

    2014-01-31

    There is an increased need to more fully assess and control the composition of kerosene-based rocket propulsion fuels such as RP-1. In particular, it is critical to make better quantitative connections among the following three attributes: fuel performance (thermal stability, sooting propensity, engine specific impulse, etc.), fuel properties (such as flash point, density, kinematic viscosity, net heat of combustion, and hydrogen content), and the chemical composition of a given fuel, i.e., amounts of specific chemical compounds and compound classes present in a fuel as a result of feedstock blending and/or processing. Recent efforts in predicting fuel chemical and physical behavior through modeling put greater emphasis on attaining detailed and accurate fuel properties and fuel composition information. Often, one-dimensional gas chromatography (GC) combined with mass spectrometry (MS) is employed to provide chemical composition information. Building on approaches that used GC-MS, but to glean substantially more chemical information from these complex fuels, we recently studied the use of comprehensive two dimensional (2D) gas chromatography combined with time-of-flight mass spectrometry (GC×GC-TOFMS) using a "reversed column" format: RTX-wax column for the first dimension, and a RTX-1 column for the second dimension. In this report, by applying chemometric data analysis, specifically partial least-squares (PLS) regression analysis, we are able to readily model (and correlate) the chemical compositional information provided by use of GC×GC-TOFMS to RP-1 fuel property information such as density, kinematic viscosity, net heat of combustion, and so on. Furthermore, we readily identified compounds that contribute significantly to measured differences in fuel properties based on results from the PLS models. We anticipate this new chemical analysis strategy will have broad implications for the development of high fidelity composition-property models, leading to an

  17. Correlation of rocket propulsion fuel properties with chemical composition using comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry followed by partial least squares regression analysis

    Energy Technology Data Exchange (ETDEWEB)

    Kehimkar, Benjamin; Hoggard, Jamin C.; Marney, Luke C.; Billingsley, Matthew; Fraga, Carlos G.; Bruno, Thomas J.; Synovec, Robert E.

    2014-01-31

    There is an increased need to more fully assess and control the composition of kerosene based rocket propulsion fuels, namely RP-1 and RP-2. In particular, it is crucial to be able to make better quantitative connections between the following three attributes: (a) fuel performance, (b) fuel properties (flash point, density, kinematic viscosity, net heat of combustion, hydrogen content, etc) and (c) the chemical composition of a given fuel (i.e., specific chemical compounds and compound classes present as a result of feedstock blending and processing). Indeed, recent efforts in predicting fuel performance through modeling put greater emphasis on detailed and accurate fuel properties and fuel compositional information. In this regard, advanced distillation curve (ADC) metrology provides improved data relative to classical boiling point and volatility curve techniques. Using ADC metrology, data obtained from RP-1 and RP-2 fuels provides compositional variation information that is directly relevant to predictive modeling of fuel performance. Often, in such studies, one-dimensional gas chromatography (GC) combined with mass spectrometry (MS) is typically employed to provide chemical composition information. Building on approaches using GC-MS, but to glean substantially more chemical composition information from these complex fuels, we have recently studied the use of comprehensive two dimensional gas chromatography combined with time-of-flight mass spectrometry (GC × GC - TOFMS) to provide chemical composition data that is significantly richer than that provided by GC-MS methods. In this report, by applying multivariate data analysis techniques, referred to as chemometrics, we are able to readily model (correlate) the chemical compositional information from RP-1 and RP-2 fuels provided using GC × GC - TOFMS, to the fuel property information such as that provided by the ADC method and other specification properties. We anticipate that this new chemical analysis

  18. Repetition and Translation Shifts

    Directory of Open Access Journals (Sweden)

    Simon Zupan

    2006-06-01

    Full Text Available Repetition manifests itself in different ways and at different levels of the text. The first basic type of repetition involves complete recurrences; in which a particular textual feature repeats in its entirety. The second type involves partial recurrences; in which the second repetition of the same textual feature includes certain modifications to the first occurrence. In the article; repetitive patterns in Edgar Allan Poe’s short story “The Fall of the House of Usher” and its Slovene translation; “Konec Usherjeve hiše”; are compared. The author examines different kinds of repetitive patterns. Repetitions are compared at both the micro- and macrostructural levels. As detailed analyses have shown; considerable microstructural translation shifts occur in certain types of repetitive patterns. Since these are not only occasional; sporadic phenomena; but are of a relatively high frequency; they reduce the translated text’s potential for achieving some of the gothic effects. The macrostructural textual property particularly affected by these shifts is the narrator’s experience as described by the narrative; which suffers a reduction in intensity.

  19. Multiconfiguration calculations of electronic isotope shift factors in Al I

    CERN Document Server

    Filippin, Livio; Ekman, Jörgen; Fritzsche, Stephan; Godefroid, Michel; Jönsson, Per

    2016-01-01

    The present work reports results from systematic multiconfiguration Dirac-Hartree-Fock calculations of electronic isotope shift factors for a set of transitions between low-lying states in neutral aluminium. These electronic quantities together with observed isotope shifts between different pairs of isotopes provide the changes in mean-square charge radii of the atomic nuclei. Two computational approaches are adopted for the estimation of the mass- and field shift factors. Within these approaches, different models for electron correlation are explored in a systematic way to determine a reliable computational strategy and estimate theoretical uncertainties of the isotope shift factors.

  20. Prediction of β-hairpin Motif in Enzyme Based on Values of Matrix Scoring and Averaged Chemical Shifts%基于矩阵打分值和化学位移值预测酶蛋白质中β-发夹模体

    Institute of Scientific and Technical Information of China (English)

    宋航宇; 胡秀珍

    2014-01-01

    Enzyme is a kind of protein that acts with catalytic functions in living organisms ,thus the study of the structure and function of enzyme is essential .β-hairpin is a specific super -secondary structure motif which carries abundant folding information .The prediction of β-hairpin motifs in en-zyme protein is helpful to study the structure and function of enzyme .In this paper ,we constructed a non-redundant β-hairpin database ,w hich have 2 ,818β-hairpins and 1 ,098 non-β-hairpins motif in 1 ,080 enzyme protein chains .The hydropaths composed of position and adjacent to dipeptide hydro-paths composition of position extracted as parameter for matrix scoring algorithm ,the prediction re-sults were unsatisfactory .Then ,we selected the scores of hydropathy composition of position ,the scores of adjacent to dipeptide hydropathy composition of position and averaged chemical shift as the in-put parameters for Support Vector Machine algorithm ,the overall accuracy and Matthew ’s correlation coefficient reached 81 .8% and 0 .636 respectively by 5-fold cross-validation .%酶是一类具有催化功能的蛋白质,对其结构和功能的研究是非常有必要的。特殊模体β-发夹是一种简单的超二级结构,它们包含了丰富的折叠信息,对酶中β-发夹的预测有助于酶结构和功能的预测。本文建立了非冗余的β-发夹模体数据集,包含1080条酶蛋白质链,2818个β-发夹模体,1098个非β-发夹。提取位点亲疏水组分及位点亲疏水紧邻关联组分作为参数,运用矩阵打分算法得到的预测结果不理想。将位点亲疏水、位点亲疏水紧邻关联组分为参数得到的打分值和平均化学位移值共同作为特征参数,输入支持向量机算法对模体进行预测,5交叉检验预测总精度是81.8%,相关系数达到了0.636。

  1. Preliminary results of determination of chemical changes on Lingzhi or Reishi medicinal mushroom, Ganoderma lucidum (W.Curt.:Fr.)P. Karst. (higher Basidiomycetes) carried by Shenzhou I spaceship with FTIR and 2D-IR correlation spectroscopy.

    Science.gov (United States)

    Choong, Yew Keong; Chen, Xiangdong; Jamal, Jamia Azdina; Wang, Qiuying; Lan, Jin

    2012-01-01

    Spaceflight represents a complex environmental condition. Space mutagenesis breeding has achieved marked results over the years. The objective of this study is to determine the chemical changes in medicinal mushroom Ganoderma lucidum cultivated after spaceflight in 1999. Fourier transform infrared (FTIR) and two-dimensional infrared (2DIR) correlation spectroscopy were used in analysis. The sample Sx and its control Cx showed the least dissimilarities in one-dimensional FTIR spectra, but absorbance of Sx is twice as high as Cx. Sx presented a clear peak at 1648 cm in 2nd derivative spectra, which could not be detected in the Cx. The 2DIR spectra showed the intensity of Sx in the range 1800-1400 cm-1 for protein is higher than the control. The sample Sx produced some carbohydrate peaks in the area of 889 cm-1 compared with the Cx. The spaceflight set up an extreme condition and caused changes of chemical properties in G. lucidum strain.

  2. 杂苯C5H5X(X=N,P,As,Sb,Bi)芳香性的核独立化学位移(NICS)与异构体稳定化能(ISE)研究%Study on the Aromaticity of Heterobenzenes C5H5X(X=N,P,As,Sb,Bi)by Nucleus Independent Chemical Shifts(NICS)and Isomerization Stabilization Energies(ISE)

    Institute of Scientific and Technical Information of China (English)

    易平贵; 侯博; 汪朝旭; 刘峥军; 于贤勇; 徐百元

    2013-01-01

    In different research fields nucleus independent chemical shift (NICS) has been used frequently as a convenient tool for obtaining information about induced dia-paratropic and paratropic ring currents, especially for the purpose of assigning aromaticity and anti-aromaticity to molecules, obviously, aromaticities and magnetic properties of molecules can be measured by NICS. This paper presents the investigation on some important features of benzene and heterobenzenes C5H5X (X=CH, N, P, As, Sb, Bi) based on the analyzing maximum value of NICS above the cycle planar about 0.8~0.9 A. Compared with density functional theory (DFT), the calculated results by ab initio (HF) are more accurate and acceptable for the NICS of heterobenzenes. There are two primary reasons to explain the phenomenon. First, the correlation coefficient of the proton chemical shifts of 1H NMR between calculated and experimental data by HF method is larger than adopted DFT methods. Second, because the ghost position plays a critical role in judging aromaticity, only involving HF method satisfy the results through comparing NICS(l) with the aromaticity of benzene, pyridine and other heterobenzenes in normal temperature and pressure. Furthermore, according to the calculation of natural localized molecular orbitals (NLMO), we can get a conclusion that the π bonds are main contributions to the zz tensor of NlCS(max), and the order is benzene > pyridine > phosphabenzene > arsabenzene > stibabenzene > bimabenzene. σ bonds all show σ aromaticity. However, other bonds' anti-aromaticity is revealed. In order to be further studied for aromaticity and chemical shifts of 1H NMR about the heterobenzenes, the magnitudes induced are depicted by the outer magnetic field. For pyridine, the magnitudes of red area coincide with the proton chemical shifts (α-H>γ-H>β-H); others are in accord with the order (α-H>β-H>γ-H). Finally, the induced magnitudes by the outer magnetic field show the same global

  3. Alcaloides iboga de Peschiera affinis (Apocynaceae - Atribuição inequívoca dos deslocamentos químicos dos átomos de hidrogênio e carbono: atividade antioxidante Iboga alkaloids from Peschiera affinis (Apocynaceae - unequivocal 1H and 13C chemical shift assignments: antioxidant activity

    Directory of Open Access Journals (Sweden)

    Allana Kellen L. Santos

    2009-01-01

    Full Text Available Six known alkaloids iboga type and the triterpen α- and β-amyrin acetate were isolated from the roots and stems of Peschiera affinis. Their structures were characterized on the basis of spectral data mainly NMR and mass spectra. 1D and 2D NMR spectra were also used to unequivocal ¹H and 13C chemical shift assignments of alkaloids. The ethanolic extract of roots, alkaloidic and no-alkaloidic fractions and iso-voacristine hydroxyindolenine and voacangine were evaluated for their antioxidative properties using an autographic assay based on β-carotene bleaching on TLC plates, and also spectrophotometric detection by reduction of the stable DPPH (2,2-diphenyl-1-picrylhydrazyl free radical.

  4. 鲜榨苹果汁的理化特性和感官品质相关性%Correlations between Physico-chemical Characteristics and Sensory Quality of Fresh Apple Juice

    Institute of Scientific and Technical Information of China (English)

    袁亚宏; 王周利; 李彩霞; 岳田利; 赵镭

    2012-01-01

    The aim of the present study was to explore the correlations between physico-chemical characteristics and sensory measures of fresh apple juice from 9 varieties. The results showed that: 1) there were significant correlations among partial physico-chemical characteristics of apple juice; 2) significant correlations were found between physicochemical characteristics and sensory measures of apple juice. The fruity aroma of apple juice was significantly correlated with its pH and titratable acidity. A positive correlation was observed between the faint scent and color value or total sugar content. The astringent taste had a positive correlation with the titratable acidity total phenol content or buffer capacity, but revealed a negative correlation with the pH, sugar/acid ratio or solid/acid ratio. The acidic taste was correlated with the pH, total sugar content, titratable acidity, buffer capacity, sugar/acid ratio or solid/acid ratio. Moreover, the sweet taste presented a correlation with soluble solid content (SSC), titratable acidity, buffer capacity or solid/acid ratio; 3)the developed regression model for taste evaluation of apple juice was significant, indicating that there are good correlations between physico-chemical characteristics and sensory measures of fresh apple juice. Thus physicochemical characteristics can be measures for predictive analysis of the sensory quality of fresh apple juice.%以9种苹果鲜榨汁为材料,通过理化指标测定和感官评价,研究鲜榨苹果汁理化特性和感官品质之间的相关性。结果表明:1)部分理化指标之间具有显著的相关性;2)理化指标与感官特性之间存在显著的相关性:苹果香与pH值、可滴定酸含量有显著的相关性;清香与色值、总糖含量呈正相关;涩味与可滴定酸含量、多酚含量、缓冲容量成正相关,与pH值、糖酸比、固酸比呈现显著的负相关;酸味与pH值、总糖含量、可滴定酸含量、缓

  5. Two-dimensional NMR measurement and point dipole model prediction of paramagnetic shift tensors in solids

    Energy Technology Data Exchange (ETDEWEB)

    Walder, Brennan J.; Davis, Michael C.; Grandinetti, Philip J. [Department of Chemistry, Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210 (United States); Dey, Krishna K. [Department of Physics, Dr. H. S. Gour University, Sagar, Madhya Pradesh 470003 (India); Baltisberger, Jay H. [Division of Natural Science, Mathematics, and Nursing, Berea College, Berea, Kentucky 40403 (United States)

    2015-01-07

    A new two-dimensional Nuclear Magnetic Resonance (NMR) experiment to separate and correlate the first-order quadrupolar and chemical/paramagnetic shift interactions is described. This experiment, which we call the shifting-d echo experiment, allows a more precise determination of tensor principal components values and their relative orientation. It is designed using the recently introduced symmetry pathway concept. A comparison of the shifting-d experiment with earlier proposed methods is presented and experimentally illustrated in the case of {sup 2}H (I = 1) paramagnetic shift and quadrupolar tensors of CuCl{sub 2}⋅2D{sub 2}O. The benefits of the shifting-d echo experiment over other methods are a factor of two improvement in sensitivity and the suppression of major artifacts. From the 2D lineshape analysis of the shifting-d spectrum, the {sup 2}H quadrupolar coupling parameters are 〈C{sub q}〉 = 118.1 kHz and 〈η{sub q}〉 = 0.88, and the {sup 2}H paramagnetic shift tensor anisotropy parameters are 〈ζ{sub P}〉 = − 152.5 ppm and 〈η{sub P}〉 = 0.91. The orientation of the quadrupolar coupling principal axis system (PAS) relative to the paramagnetic shift anisotropy principal axis system is given by (α,β,γ)=((π)/2 ,(π)/2 ,0). Using a simple ligand hopping model, the tensor parameters in the absence of exchange are estimated. On the basis of this analysis, the instantaneous principal components and orientation of the quadrupolar coupling are found to be in excellent agreement with previous measurements. A new point dipole model for predicting the paramagnetic shift tensor is proposed yielding significantly better agreement than previously used models. In the new model, the dipoles are displaced from nuclei at positions associated with high electron density in the singly occupied molecular orbital predicted from ligand field theory.

  6. Constant-time 2D and 3D through-bond correlation NMR spectroscopy of solids under 60 kHz MAS

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Rongchun; Ramamoorthy, Ayyalusamy, E-mail: ramamoor@umich.edu [Biophysics and Department of Chemistry, The University of Michigan, Ann Arbor, Michigan 48109-1055 (United States)

    2016-01-21

    Establishing connectivity and proximity of nuclei is an important step in elucidating the structure and dynamics of molecules in solids using magic angle spinning (MAS) NMR spectroscopy. Although recent studies have successfully demonstrated the feasibility of proton-detected multidimensional solid-state NMR experiments under ultrafast-MAS frequencies and obtaining high-resolution spectral lines of protons, assignment of proton resonances is a major challenge. In this study, we first re-visit and demonstrate the feasibility of 2D constant-time uniform-sign cross-peak correlation (CTUC-COSY) NMR experiment on rigid solids under ultrafast-MAS conditions, where the sensitivity of the experiment is enhanced by the reduced spin-spin relaxation rate and the use of low radio-frequency power for heteronuclear decoupling during the evolution intervals of the pulse sequence. In addition, we experimentally demonstrate the performance of a proton-detected pulse sequence to obtain a 3D {sup 1}H/{sup 13}C/{sup 1}H chemical shift correlation spectrum by incorporating an additional cross-polarization period in the CTUC-COSY pulse sequence to enable proton chemical shift evolution and proton detection in the incrementable t{sub 1} and t{sub 3} periods, respectively. In addition to through-space and through-bond {sup 13}C/{sup 1}H and {sup 13}C/{sup 13}C chemical shift correlations, the 3D {sup 1}H/{sup 13}C/{sup 1}H experiment also provides a COSY-type {sup 1}H/{sup 1}H chemical shift correlation spectrum, where only the chemical shifts of those protons, which are bonded to two neighboring carbons, are correlated. By extracting 2D F1/F3 slices ({sup 1}H/{sup 1}H chemical shift correlation spectrum) at different {sup 13}C chemical shift frequencies from the 3D {sup 1}H/{sup 13}C/{sup 1}H spectrum, resonances of proton atoms located close to a specific carbon atom can be identified. Overall, the through-bond and through-space homonuclear/heteronuclear proximities determined from the

  7. Constant-time 2D and 3D through-bond correlation NMR spectroscopy of solids under 60 kHz MAS.

    Science.gov (United States)

    Zhang, Rongchun; Ramamoorthy, Ayyalusamy

    2016-01-21

    Establishing connectivity and proximity of nuclei is an important step in elucidating the structure and dynamics of molecules in solids using magic angle spinning (MAS) NMR spectroscopy. Although recent studies have successfully demonstrated the feasibility of proton-detected multidimensional solid-state NMR experiments under ultrafast-MAS frequencies and obtaining high-resolution spectral lines of protons, assignment of proton resonances is a major challenge. In this study, we first re-visit and demonstrate the feasibility of 2D constant-time uniform-sign cross-peak correlation (CTUC-COSY) NMR experiment on rigid solids under ultrafast-MAS conditions, where the sensitivity of the experiment is enhanced by the reduced spin-spin relaxation rate and the use of low radio-frequency power for heteronuclear decoupling during the evolution intervals of the pulse sequence. In addition, we experimentally demonstrate the performance of a proton-detected pulse sequence to obtain a 3D (1)H/(13)C/(1)H chemical shift correlation spectrum by incorporating an additional cross-polarization period in the CTUC-COSY pulse sequence to enable proton chemical shift evolution and proton detection in the incrementable t1 and t3 periods, respectively. In addition to through-space and through-bond (13)C/(1)H and (13)C/(13)C chemical shift correlations, the 3D (1)H/(13)C/(1)H experiment also provides a COSY-type (1)H/(1)H chemical shift correlation spectrum, where only the chemical shifts of those protons, which are bonded to two neighboring carbons, are correlated. By extracting 2D F1/F3 slices ((1)H/(1)H chemical shift correlation spectrum) at different (13)C chemical shift frequencies from the 3D (1)H/(13)C/(1)H spectrum, resonances of proton atoms located close to a specific carbon atom can be identified. Overall, the through-bond and through-space homonuclear/heteronuclear proximities determined from the 3D (1)H/(13)C/(1)H experiment would be useful to study the structure and dynamics of

  8. Performance of density functional theory methods to describe intramolecular hydrogen shifts

    Indian Academy of Sciences (India)

    Nelly González-Rivas; Andrés Cedillo

    2005-09-01

    The performance of three exchange and correlation density functionals, LDA, BLYP and B3LYP, with four basis sets is tested in three intramolecular hydrogen shift reactions. The best reaction and activation energies come from the hybrid functional B3LYP with triple- basis sets, when they are compared with high-level post-Hartree-Fock results from the literature. For a fixed molecular geometry, the electrophilic Fukui function is computed from a finite difference approximation. Fukui function shows a small dependence with both the exchange and correlation functional and the basis set. Evolution of the Fukui function along the reaction path describes important changes in the basic sites of the corresponding molecules. These results are in agreement with the chemical behavior of those species.

  9. Bond-length analysis of the omega structure in Ti,Zr,Hf and their alloys: experimental data, new correlations and implications for chemical bonding models

    Energy Technology Data Exchange (ETDEWEB)

    Grad, G.B.; Benites, G.M. [Comision Nacional de Energia Atomica, San Carlos de Bariloche (Argentina). Centro Atomico Bariloche; Aurelio, G. [Departamento de Fisica, Universidad del Comahue, 8300, Neuquen (Argentina); Fernandez Guillermet, A. [Centro Atomico Bariloche, 8400, San Carlos de Bariloche (Argentina)

    1999-12-15

    An analysis is performed of the experimental information on the key interatomic distances (IDs) of the AlB{sub 2} type structure, the so-called omega ({omega}) phase in Ti and Zr, as well as in Ti-V and Zr-Nb alloys. Various remarkable correlations are found between these IDs and standard measures of the atomic size, and with Pauling's bond-lengths. These observations are discussed in the light of the phenomenological bonding pictures of the {omega} structure, and with our recent ab initio calculations of the electronic structure of this phase. (orig.)

  10. Shape-shifting colloids via stimulated dewetting

    Science.gov (United States)

    Youssef, Mena; Hueckel, Theodore; Yi, Gi-Ra; Sacanna, Stefano

    2016-07-01

    The ability to reconfigure elementary building blocks from one structure to another is key to many biological systems. Bringing the intrinsic adaptability of biological systems to traditional synthetic materials is currently one of the biggest scientific challenges in material engineering. Here we introduce a new design concept for the experimental realization of self-assembling systems with built-in shape-shifting elements. We demonstrate that dewetting forces between an oil phase and solid colloidal substrates can be exploited to engineer shape-shifting particles whose geometry can be changed on demand by a chemical or optical signal. We find this approach to be quite general and applicable to a broad spectrum of materials, including polymers, semiconductors and magnetic materials. This synthetic methodology can be further adopted as a new experimental platform for designing and rapidly prototyping functional colloids, such as reconfigurable micro swimmers, colloidal surfactants and switchable building blocks for self-assembly.

  11. Energy phase shift as mechanism for catalysis

    KAUST Repository

    Beke-Somfai, Tamás

    2012-05-01

    Catalysts are agents that by binding reactant molecules lower the energy barriers to chemical reaction. After reaction the catalyst is regenerated, its unbinding energy recruited from the environment, which is associated with an inevitable loss of energy. We show that combining several catalytic sites to become energetically and temporally phase-shifted relative to each other provides a possibility to sustain the overall reaction by internal \\'energy recycling\\', bypassing the need for thermal activation, and in principle allowing the system to work adiabatically. Using an analytical model for superimposed, phase-shifted potentials of F 1-ATP synthase provides a description integrating main characteristics of this rotary enzyme complex. © 2012 Elsevier B.V. All rights reserved.

  12. Study on the correlation between chemical and mineral composition of coal ashes; Sekitanbaibun no kobutsu soseigakuteki kento kagakubutsu sosei to kobutsugakuteki sosei no sokan

    Energy Technology Data Exchange (ETDEWEB)

    Hirato, M.; Nagashima, S.; Okada, S. [Hachinohe Institute of Technology, Aomori (Japan)

    1996-10-28

    Coal ash is a substance that has been mixed into minerals in the earth`s crust during their coalification process. Estimation was made on what kinds of mineral composition have been mixed into coals. Noted first was the kinds of compounds contained in the ash, wherein the ratios of mass in the compounds and minerals were correlated, and selection was made on minerals which are thought correlated. The selection criterion was based on minerals containing silica, alumina, iron oxide, lime and magnesium as compounds. Then, a phase equilibrium line diagram was used to estimate compositions and melting points of minerals which are thought to have been produced from these compounds. By comparing the estimation with the measured melting points of the ashes, mineral compositions thought reasonable were all selected. Assumption was possible on minerals that are thought to have been transferred into coal ash. Compound indications of ashes from 29 kinds of the world`s typical coals were replaced with the subject minerals and expressed as mineral compositions. As a method of calculation, stoichiometric coefficients for each mineral were determined by taking material balance in atomic/molecular levels in masses of compound aggregates and mineral composition aggregates. 7 tabs.

  13. Quantized beam shifts in graphene

    Energy Technology Data Exchange (ETDEWEB)

    de Melo Kort-Kamp, Wilton Junior [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Sinitsyn, Nikolai [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dalvit, Diego Alejandro Roberto [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-10-08

    We predict the existence of quantized Imbert-Fedorov, Goos-Hanchen, and photonic spin Hall shifts for light beams impinging on a graphene-on-substrate system in an external magnetic field. In the quantum Hall regime the Imbert-Fedorov and photonic spin Hall shifts are quantized in integer multiples of the fine structure constant α, while the Goos-Hanchen ones in multiples of α2. We investigate the influence on these shifts of magnetic field, temperature, and material dispersion and dissipation. An experimental demonstration of quantized beam shifts could be achieved at terahertz frequencies for moderate values of the magnetic field.

  14. Beam shifts and distribution functions

    CERN Document Server

    Aiello, Andrea

    2011-01-01

    When a beam of light is reflected by a smooth surface its behavior deviates from geometrical optics predictions. Such deviations are quantified by the so-called spatial and angular Goos-Haenchen (GH) and Imbert-Fedorov (IF) shifts of the reflected beam. These shifts depend upon the shape of the incident beam, its polarization and on the material composition of the reflecting surface. In this article we suggest a novel approach that allows one to unambiguously isolate the beam-shape dependent aspects of GH and IF shifts. We show that this separation is possible as a result of some universal features of shifted distribution functions which are presented and discussed.

  15. [Correlations between standing trees trunk decay degree and soil physical-chemical properties in Korean pine-broadleaved mixed forest in Xiao Xing'an Mountains of Northeast China].

    Science.gov (United States)

    Sun, Tian-Yong; Wang, Li-Hai; Sun, Mo-Long

    2013-07-01

    Standing trees decay often causes vast loss of timber resources. To investigate the correlations between the standing trees decay and the site conditions is of importance to scientifically and reasonably manage forests and to decrease wood resources loss. By using Resistograph and meter ruler, a measurement was made on the decay degree of the trunk near root and the diameter at breast height (DBH) of 15 mature Korean pine standing trees in a Korean pine-broadleaved mixed forest in Xiao Xing' an Mountains in May, 2011. In the meantime, soil samples were collected from the root zones of standing trees and the upslope and downslope 5 meters away from the trunks, respectively. Five physical-chemical properties including moisture content, bulk density, total porosity, pH value, and organic matter content of the soil samples were tested. The regression equations concerning the trunk decay degree of the standing trees, their DBH, and the 5 soil properties were established. The results showed that the trunk decay degree of the mature Korean pine standing trees had higher correlations with the bulk density, total porosity, pH value, and organic matter content (R = 0.687), and significant positive correlation with the moisture content (R = 0.507) of the soils at the root zones of standing trees, but less correlation with the 5 properties of the soils at both upslope and downslope 5 meters away from the trunks. The trunk decay degree was decreased when the soil moisture content was below 18.4%. No significant correlation was observed between the trunk decay degree of mature Korean pine standing trees and the tree age.

  16. Analysis of Correlation between Climatic Factors and Conventional Chemical Composition of Flue-cured Tobacco%气候因子与烤烟常规化学成分相关性分析

    Institute of Scientific and Technical Information of China (English)

    李琦; 王勇军; 蔡凤梅

    2014-01-01

    为了明确气候因子与烤烟品质之间的关系,对卢氏县2005~2012年度气象数据与当地烤烟常规化学成分含量数据进行了相关性分析。结果表明:平均气温与中部叶氯元素累积、中部叶钾氯比、下部叶糖碱比显著相关;空气相对湿度与上部叶钾元素累积显著相关,降雨量与上部叶钾、氯元素的累积和中部叶还原糖含量显著相关。在今后的烟叶生产中,可有针对性地调整烤烟的播种时间或是采取其他管理措施,来平衡烟叶中的化学成分含量,提高烟叶品质。%In order to determine the correlation between climatic factors and quality of flue-cured tobacco, a correlation analysis was conducted to the annual climate data in Lushi County from 2005 to 2012 and the conventional chemical composition content of local tobacco. The results showed that average temperature was significantly correlated with chlorine accumulation in middle leaves, ratio of potassium to chloride in middle leaves, and ratio of sugar to alkali in lower leaves; air relative humidity was significantly correlated with potassium accumulation in upper leaves; rainfall was significantly correlated with potassium accumulation and chloride accumulation in upper leaves, and reducing sugar content in middle leaves. In the future tobacco-leaf production, it could adjust sowing time of tobacco or adopting the other managing measures accordingly to balance the contents of chemical compositions in the tobacco leaves in order to improve the quality of tobacco leaves.

  17. Work shifts in Emergency Medicine

    Directory of Open Access Journals (Sweden)

    Roberto Recupero

    2007-06-01

    Full Text Available Emergency Medicine is known as a high stress specialty. The adverse effect of constantly rotating shifts is the single most important reason given for premature attrition from the field. In this work problems tied with night shift work will be taken into account and some solutions to reduce the impact of night work on the emergency physicians will be proposed.

  18. Regime shifts in resource management

    NARCIS (Netherlands)

    de Zeeuw, A.J.

    2014-01-01

    Resource management has to take account of the possibility of tipping points and regime shifts in ecological systems that provide the resources. This article focuses on the typical model of regime shifts in the ecological literature and analyzes optimal management and common-property issues when tra

  19. Korelacija rezultata ispitivanja hemijske stabilnosti prirodno i ubrzano starenih baruta / Correlation of chemical stability estimation results of naturally and accelerated aging gun powders

    Directory of Open Access Journals (Sweden)

    Luka Grbović

    2005-09-01

    Full Text Available Praćenje sadržaja stabilizatora jedna je od savremenih i pouzdanih metoda koja se u svetu, a i kod nas, primenjuje za kontrolu kemijske stabilnosti i prognoziranje veka upotrebljivosti baruta. Radi ocene pouzdanosti metode ispitivani su uzorci prirodno starenog jednobaznog baruta tipa NC i dvobaznog baruta tipa NGB različitih godina proizvodnje. Uzorci su uzimani iz ubojnih sredstava. Određene su konstante brzine reakcije utroška stabilizatora i vremena upotrebljivosti baruta. Ove vrednosti upoređene su sa analognim rezultatima dobijenim za iste barute pre dvadeset godina pri čemu je utvrđeno zadovoljavajuće slaganje kako za prirodno tako i ubrzano starenje. Pored toga, utvrđeno je da NC baruti iz dehermetizovanog pakovanja municije pokazuju znatno manju stabilnost od baruta iz originalnog pakovanja. / Monitoring the content of the stabilizer is one of the most reliable and modern methods used all over the world as well as in our country for chemical stability control and shelf life prediction of gun powders. For reliability rating of the used method, there has been examined samples of naturally aged single-based gun powder NC type and double-based gun powder NGB type all manufactured in different years. The samples were taken from explosive ordnance. Reaction rates constants of stabilizer consumption and shelf life of gun powders have been determined. These values were compared to analog results taken for the same gun powders tested 20 years ago. Satisfactory agreement either for naturally or accelerating aging gun powders has been confirmed. Beside that, it was determined that NC gun powder from non hermetic munitions cases proved to be considerably less stable than the originally packed NC gun powder.

  20. Metabolic impact of shift work.

    Science.gov (United States)

    Zimberg, Ioná Zalcman; Fernandes Junior, Silvio A; Crispim, Cibele Aparecida; Tufik, Sergio; de Mello, Marco Tulio

    2012-01-01

    In developing countries, shift work represents a considerable contingent workforce. Recently, studies have shown that overweight and obesity are more prevalent in shift workers than day workers. In addition, shift work has been associated with a higher propensity for the development of many metabolic disorders, such as insulin resistance, diabetes, dislipidemias and metabolic syndrome. Recent data have pointed that decrease of the sleep time, desynchronization of circadian rhythm and alteration of environmental aspects are the main factors related to such problems. Shortened or disturbed sleep is among the most common health-related effects of shift work. The plausible physiological and biological mechanisms are related to the activation of the autonomic nervous system, inflammation, changes in lipid and glucose metabolism, and related changes in the risk for atherosclerosis, metabolic syndrome, and type II diabetes. The present review will discuss the impact of shift work on obesity and metabolic disorders and how disruption of sleep and circadian misalignment may contribute to these metabolic dysfunctions.

  1. Electrostatics determine vibrational frequency shifts in hydrogen bonded complexes.

    Science.gov (United States)

    Dey, Arghya; Mondal, Sohidul Islam; Sen, Saumik; Ghosh, Debashree; Patwari, G Naresh

    2014-12-14

    The red-shifts in the acetylenic C-H stretching vibration of C-H∙∙∙X (X = O, N) hydrogen-bonded complexes increase with an increase in the basicity of the Lewis base. Analysis of various components of stabilization energy suggests that the observed red-shifts are correlated with the electrostatic component of the stabilization energy, while the dispersion modulates the stabilization energy.

  2. Beyond climate: disturbance niche shifts in invasive species

    OpenAIRE

    González-Moreno, Pablo; Diez, Jeffrey M.; Richardson, David M.; Vilà, Montserrat

    2015-01-01

    Analysing how species niches shift between native and introduced ranges is a powerful tool for understanding the determinants of species distributions and for anticipating range expansions by invasive species. Most studies only consider the climatic niche, by correlating widely available presence-only data with regional climate. However, habitat characteristics and disturbance also shape species niches, thereby potentially confounding shifts attributed only to differences in climate. Here we ...

  3. Correlation Analysis of Sensory Coziness and Main Chemical Indices of Flue-cured Tobacco%烤烟主要化学指标与感官舒适度的相关性分析

    Institute of Scientific and Technical Information of China (English)

    朱保昆; 朱东来; 王明锋; 赵建华; 廖头根

    2011-01-01

    To analyze the influence of main chemical indices of flue-cured tobacco on overall sensory coziness. 35 tobacco chemical indices in 50 domestic and imported representative tobacco leaves were analyzed and verified. Meanwhile, a comprehensive sensory coziness evaluation was conducted on the 50 samples. The data of chemical indicators and sensory evaluation were analyzed by multiple correlation coefficient method. The results showed that: nicotine, ratio of N to nicotine, the ratio of reducing sugar to nicotine, petroleum ether extracts and sensory comfort as a whole was significantly related (P0.05). According to the multiple correlation coefficient and significance level, the specific influence degree order of main chemical components of tobacco on the sensory comfort was nicotine > ratio of N to nicotine > the ratio of reducing sugar to nicotine > petroleum ether extract.%为了分析烤烟主要化学指标对其感官舒适度的影响,利用复相关系数分析方法对50个涵盖国内主要烟叶产区及进口烟叶原料的35个主要化学指标检测数据与感官舒适度评价数据进行分析与验证.结果表明,烤烟烟碱、氮碱比和糖碱比与感官舒适度整体上呈极显著相关(P<0.01),石油醚提取物含量与感官舒适度整体上呈显著相关(P<0.05),其余化学指标与感官舒适度10个指标得分的相关性统计上不显著(P>0.05);根据复相关系数的大小及显著性水平,烤烟主要化学成分对其感官舒适度的影响程度为:烟碱>氮碱比>糖碱比>石油醚提取物.

  4. Group Chemical Changes and Physical Property Correlations in Refining of Lube Base Stocks. Physico-Chemical and Adsorption Chromatography Parameters Corrélations entre les propriétés physiques et les changements de composition chimique au cours du raffinage des huiles de base. Paramètres physico-chimiques et de chromatographie par adsorption

    Directory of Open Access Journals (Sweden)

    Singh H.

    2006-11-01

    Full Text Available Changes in twenty-two lubricating oil base stocks prepared from Darius and Assam Mix Crudes by different types of refining treatment and severity of refining have been investigated. Changes in the viscosity index with progressive refining in base stocks of different viscosity have been studied in relation to physico-chemical properties, structural analysis and saturate contents of the base oils. Correlations between the concentration of saturates, saturate-to-aromatic ratio and VI of the base stocks are reported.

  5. Correlativity between main chemical components and smoking quality of flue-cured tobacco%烤烟主要化学成分与吸味品质的相关性

    Institute of Scientific and Technical Information of China (English)

    李朝建; 李晓刚

    2009-01-01

    The correlativity between the main chemical components and smoking quality of 55 tobacco leaf samples coming from Yunnan and Guizhou province was analyzed by using the maths' statistical methods. The results of correlative analysis were as follows. The correlative analysis between the main chemical components and smoking quality showed that aroma quality,physiological strength,offensive odor,exquisite degree,irritation,dryness,sweetness and remaining flavor were significantly correlated with the main chemical components. The aroma quality had extremely significant and positive effect on reducing sugar;The physiological strength had extremely significant and positive effect on nicotine and total nitrogen,but had significantly negative effect on the ratio of reducing sugar to nicotine;The offensive odor and exquisite degree had extremely significant and positive effect on reducing sugar;The irritation,dryness and sweetness had extreme significant positive effect on total sugar,reducing sugar and the ratio of reducing sugar to nicotine;The remaining flavor had extremely significant and positive effect on reducing sugar and the ratio of reducing sugar to nicotine,but had extremly significant and negative effect on nicotine. The method combined cluster analysis based on chemical components with cluster analysis based on on smoking quality could be used to select substitute tobacco leaves.%对云南、贵州两省C3F烟叶55个样品的常规化学成分及评吸质量进行了相关分析及Q型聚类分析.烟叶化学成分与评吸质量评价指标之间的相关分析表明:香气质、劲头、杂气、细腻度、刺激性、干燥感、甜度及余味与烟叶主要化学成分相关性显著,其中香气质与还原糖极显著正相关;劲头与烟碱、总氮极显著正相关,与糖碱比极显著负相关;杂气、细腻度与还原糖极显著正相关;刺激性、干燥感及甜度与总糖、还原糖、糖碱比极显著正相关;余味与还原糖、

  6. 3.0T1H-MRS联合梯度回波化学位移技术定量分析评估脂肪肝治疗效果%Quantification of liver fat content by 1H-MR spectroscopy combined with chemical shift gradient-echo MR imaging at 3.0T for therapeutic evaluation of fatty liver—a preliminary study

    Institute of Scientific and Technical Information of China (English)

    张羲娥; 黄子星; 袁放; 宋彬; 刘曦娇; 张威

    2012-01-01

    Objective:To investigate the feasibility of proton magnetic resonance spectroscopy OH-MRS) and chemical shift gradient-echo imaging to quantitatively analyze liver fat content for therapeutic evaluation of fatty liver at 3. OT MR system. Methods:26 patients diagnosed as fatty liver were examined with proton MRS and magnetic resonance chemical shift based fat suppression sequences(Dixon and triple-echo Dixon)at 3. OT MR system before and 3,6 months after treatment respectively to calculate the fat index(FI)of Dixon, the water peak (Pwater), fat peak (Pliptd) and water peak area (Awater),fat peak area (Aliptd) were for MRS to calculate relative lipid content KRLCDand relative lipid content 2(RLC2). Fatty liver index(FLI)was referred to the standard which was calculated from triglycerides (TG),gamma-glutamyl-trans-ferase CGGT) ,waist circumference and body mass index(BMI). Results:Significant positive correlation (r>0,P0,P<0. 05)was demonstrated in MRI measured valuesCFI, RLCl,RLC2)and FLI. Significant difference between groups was demonstrated in FI, RLC1,RLC2 and FLI. Significance in statistics was demonstrated in time* type in the Polynomial test for the comparison of time change trend which point out the significant difference of FI-,RLC1,RLC2 between pre-treatment and pos-treatment. Reliability analysis showed that FI in both pre-treatment and pos-treatment groups and RLC1 ,RLC2 in pre-treatment group got significant repeatability while ICC ≥0. 75. Conclusion:' H-MRS combined with chemical shift gradient-echo techniques can quantitatively measure liver fat content. They can be reliably used for dynamic monitoring the therapeutic effects for fatty liver. Dixon technique is more stable, while 1H-MRS is more accurate. Both 1H-MRS and Dixon technique have good clinical application in dynamically monitoring the progression of fatty liver and evaluating the therapeutic effects of various treatments.%目的:探讨在3.0T MRI上联合运用氢质子波谱成像(1H-MRS

  7. Computational Protocols for Prediction of Solute NMR Relative Chemical Shifts

    DEFF Research Database (Denmark)

    Eriksen, Janus Juul; Olsen, Jógvan Magnus Haugaard; Aidas, Kestutis;

    2011-01-01

    In this study, we have applied two different spanning protocols for obtaining the molecular conformations of L-tryptophan in aqueous solution, namely a molecular dynamics simulation and a molecular mechanics conformational search with subsequent geometry re-optimization of the stable conformers...... using a quantum mechanically based method. These spanning protocols represent standard ways of obtaining a set of conformations on which NMR calculations may be performed. The results stemming from the solute–solvent configurations extracted from the MD simulation at 300 K are found to be inferior...

  8. 15N NMR chemical shifts in papaverine decomposition products

    Science.gov (United States)

    Czyrski, Andrzej; Girreser, Ulrich; Hermann, Tadeusz

    2013-03-01

    Papaverine can be easily oxidized to papaverinol, papaveraldine and 2,3,9,10-tetramethoxy-12-oxo-12H-indolo[2,1-a]isoquinolinium chloride. On addition of alkali solution the latter compound forms 2-(2-carboxy-4,5-dimethoxyphenyl)-6,7-dimethoxyisoquinolinium inner salt. Together with these structures the interesting 13-(3,4-dimethoxyphenyl)-2,3,8,9-tetramethoxy-6a-12a-diazadibenzo[a,g]fluorenylium chloride is discussed, which is formed in the Gadamer-Schulemann reaction of papaverine as a side product. This letter reports the 15N NMR spectra of the above mentioned compounds.

  9. Thermal field theories and shifted boundary conditions

    CERN Document Server

    Giusti, Leonardo

    2013-01-01

    The analytic continuation to an imaginary velocity of the canonical partition function of a thermal system expressed in a moving frame has a natural implementation in the Euclidean path-integral formulation in terms of shifted boundary conditions. The Poincare' invariance underlying a relativistic theory implies a dependence of the free-energy on the compact length L_0 and the shift xi only through the combination beta=L_0(1+xi^2)^(1/2). This in turn implies that the energy and the momentum distributions of the thermal theory are related, a fact which is encoded in a set of Ward identities among the correlators of the energy-momentum tensor. The latter have interesting applications in lattice field theory: they offer novel ways to compute thermodynamic potentials, and a set of identities to renormalize non-perturbatively the energy-momentum tensor. At fixed bare parameters the shifted boundary conditions also provide a simple method to vary the temperature in much smaller steps than with the standard procedur...

  10. VP Anaphors and Object Shift

    DEFF Research Database (Denmark)

    Ørsnes, Bjarne

    2013-01-01

    The article discusses the placement of the VP anaphor det ‘it’ as a complement of verbs selecting VP complements in Danish. With verbs that only allow a VP complement, the VP anaphor must be in SpecCP regardless of its information structure properties. If SpecCP is occupied by an operator, the an...... be in situ. The article argues that a shifted pronominal in Danish must be categorially licensed by the verb and extends this analysis to shifting locatives. An Optimality Theory analysis is proposed that accounts for the observed facts......., the anaphor can be in situ, but it cannot shift. With verbs that allow its VP complement to alternate with an NP complement, the VP anaphor can be in SpecCP, shifted or in situ according to the information structural properties of the anaphor. Only if SpecCP is occupied by an operator, must a topical anaphor...

  11. Explaining (Missing) Regulator Paradigm Shifts

    DEFF Research Database (Denmark)

    Wigger, Angela; Buch-Hansen, Hubert

    2014-01-01

    The global financial and economic crisis has prompted some scholars to suggest that a fundamental regulatory shift away from neoliberalism will take place – both in general and in the field of EU competition regulation. This paper shows that so far no radical break with the neoliberal type...... of competition regulation is heaving into sight. It sets out to explain this from the vantage point of a critical political economy perspective, which identifies the circumstances under which a crisis can result in a regulatory paradigm shift. Contrasting the current situation with the shift in EC/EU competition...... capitalism; the social power configuration underpinning the neoliberal order remains unaltered; no clear counter-project has surfaced; the European Commission has been (and remains) in a position to oppose radical changes; and finally, there are no signs of a wider paradigm shift in the EU's regulatory...

  12. Shift Work: Improving Daytime Sleep

    Science.gov (United States)

    ... sleeping during the day. Do you have any sleep tips for shift workers? Answers from Timothy Morgenthaler, ... to be awake during the day and to sleep at night. Good daytime sleep is possible, though, ...

  13. Chemical and thermal stability of insulin

    DEFF Research Database (Denmark)

    Huus, Kasper; Havelund, Svend; Olsen, Helle B;

    2006-01-01

    To study the correlation between the thermal and chemical stability of insulin formulations with various insulin hexamer ligands.......To study the correlation between the thermal and chemical stability of insulin formulations with various insulin hexamer ligands....

  14. Goos-Hänchen shift.

    Science.gov (United States)

    Snyder, A W; Love, J D

    1976-01-01

    An extremely simple derivation of the Goos-Hänchen shift is presented for total internal reflection at a plane interface between two semiinfinite dielectric media, as well as for optical waveguides of plane arid circular cross section. The derivation is based on energy considerations, requires knowledge of Fresnel's equation only, and shows explicitly that the shift is due to the flow of energy across the dielectric boundary.

  15. 卷烟烟气指标与烟丝化学成分的相关性%Correlation Between Smoke Indexes of Cigarette and Chemical Components of Cut Tobacco

    Institute of Scientific and Technical Information of China (English)

    张国建

    2014-01-01

    The relational degree between smoke index of cigarette and chemical components of cut tobacco was determined by the grey correlation analysis.The relational degree between tar and total sugar was up to 0.80 (the highest)and the relational degree between tar of cigarette and chemical components of cut tobacco was total sugar>reducing sugar>sugar-nicotine ratio>total nitrogen=total nicotine>nitrogen-nicotine ratio>K-Chl ratio>K>Chl The relational degree between cigarette’s nicotine content and total nicotine content of cut tobacco reached 0.78 and the relational degree between cigarette’s nicotine content and chemical components of cut tobacco was total nicotine>total sugar=reducing sugar>total nitrogen>sugar-nicotine ratio>K-Chl ratio>nitrogen-nicotine ratio>K>Chl.The relational degree between cigarette’s CO content and total nitrogen content of cut tobacco was 0.71 and the relational degree between cigarette’s CO content and chemical components of cut tobacco was total nitrogen>K-Chl ratio>total nicotine>nitrogen-nicotine ratio>sugar-nicotine ratio=total sugar>K>reducing sugar>Chl.%为探明卷烟烟气指标与烟丝化学成分的相关性,采用灰色关联分析方法,研究了卷烟烟气指标与烟丝化学成分之间的关联度。结果表明:焦油关联度总糖最高,达0.80,各指标大小依次为总糖>还原糖>糖碱比>总氮=总烟碱>氮碱比>钾氯比>钾>氯;烟碱关联度总烟碱最高,达0.78,各指标大小依次为总烟碱>总糖=还原糖>总氮>糖碱比>钾氯比>氮碱比>钾>氯;CO关联度总氮最高,达0.71,各指标大小依次为总氮>钾氯比>总烟碱>氮碱比>糖碱比=总糖>钾>还原糖>氯。

  16. Clinical investigation of set-shifting subtypes in anorexia nervosa.

    Science.gov (United States)

    Abbate-Daga, Giovanni; Buzzichelli, Sara; Marzola, Enrica; Amianto, Federico; Fassino, Secondo

    2014-11-30

    While evidence continues to accumulate on the relevance of cognitive inflexibility in anorexia nervosa (AN), its clinical correlates remain unclear. We aimed at examining the relationship between set-shifting and clinical variables (i.e., eating psychopathology, depression, and personality) in AN. Ninety-four individuals affected by AN and 59 healthy controls (HC) were recruited. All participants were assessed using: Eating Disorders Inventory-2 (EDI-2), Temperament and Character Inventory (TCI), Beck Depression Inventory (BDI), and Wisconsin Card Sorting Test (WCST). The AN group scored worse than HCs on set-shifting. According to their neuropsychological performances, AN patients were split into two groups corresponding to poor (N=30) and intact (N=64) set-shifting subtypes. Interoceptive awareness, impulse regulation, and maturity fears on the EDI-2 and depression on the BDI differed across all groups (HC, intact, and poor set-shifting subtype). Self-directedness on the TCI differed significantly among all groups. Cooperativeness and reward dependence differed instead only between HC and AN poor set-shifting subtype. After controlling for depression, only interoceptive awareness remained significant with reward dependence showing a trend towards statistical significance. These findings suggest that multiple clinical variables may be correlated with set-shifting performances in AN. The factors contributing to impaired cognitive inflexibility could be more complex than heretofore generally considered.

  17. 氟斑牙检出率与病区土壤化学元素含量相关性研究%Correlation between prevalence of dental fluorosis and soil chemical elements in endemic fluorosis areas

    Institute of Scientific and Technical Information of China (English)

    闫菊; 钟朝晖; 黄巧; 王力; 雍开文; 张茂忠; 罗兴建; 晏维

    2013-01-01

    Objective To explore the correlation between chemical elements in soil and dental fluorosis and to provide a scientific basis for prevention of endemic fluorosis.Methods In 2011,using cluster sampling,totally 38 of 55 townships (towns) in Fengjie and Wushan Counties were selected as investigation spots.Dental fluorosis of children aged 8 to 12 were examined with Dean index in all individuals from the sampled townships (towns).We also detected the content of fluorine(F),zinc(Zn),copper(Cu),iodine(I),selenium(Se),cadmium (Cd),chromium (Cr),arsenic (As),nickel (Ni),mercury (Hg) and lead (Pb) in topsoil of sampled townships (towns).Using Spearman rank correlation analysis the correlation between dental fluorosis prevalence and the content of chemical elements in the topsoil of selected townships (towns) was analyzed.Results Children's dental fluorosis prevalence was positively correlated with surface soil F and Cd content in Wushan County,but negatively correlated with the content of Cu,Zn and Se,and the correlation coefficients were 1.0000,0.9053,-0.6617,-0.7353 and-0.5143,respectively (P < 0.05).Children's dental fluorosis detection rate was also positively correlated with the surface soil content of F and Cd in Fengjie County,but also negatively correlated with the content of Cu,Zn and Se,and the correlation coefficients were 0.9959,0.9298,-0.5728,-0.8308 and-0.6533,respectively(P <0.05).Conclusions The relationship between detection rate of children's dental fluorosis and the content of F,Cd,Cu,Zn and Se in topsoil was positively or negatively correlated in Fengjie and Wushan Counties.And the relationship between these elements and endemic fluorosis should be further studied.%目的 探索土壤中的化学元素与氟斑牙的关系,为地方性氟中毒的防治提供科学依据.方法 2011年,在巫山县与奉节县的55个乡(镇)中,采取整群随机抽样方法,选择38个乡(镇),采用Dean法对所有8~ 12岁儿童进行氟斑牙检查,并检测

  18. Electron correlation in molecules

    CERN Document Server

    Wilson, S

    2007-01-01

    Electron correlation effects are of vital significance to the calculation of potential energy curves and surfaces, the study of molecular excitation processes, and in the theory of electron-molecule scattering. This text describes methods for addressing one of theoretical chemistry's central problems, the study of electron correlation effects in molecules.Although the energy associated with electron correlation is a small fraction of the total energy of an atom or molecule, it is of the same order of magnitude as most energies of chemical interest. If the solution of quantum mechanical equatio

  19. A generalized Ramsey excitation scheme with suppressed light shift

    CERN Document Server

    Huntemann, N; Okhapkin, M; Tamm, Chr; Peik, E; Taichenachev, A V; Yudin, V I

    2012-01-01

    We experimentally investigate a recently proposed optical excitation scheme [V.I. Yudin et al., Phys. Rev. A 82, 011804(R)(2010)] that is a generalization of Ramsey's method of separated oscillatory fields and consists of a sequence of three excitation pulses. The pulse sequence is tailored to produce a resonance signal which is immune to the light shift and other shifts of the transition frequency that are correlated with the interaction with the probe field. We investigate the scheme using a single trapped 171Yb+ ion and excite the highly forbidden 2S1/2-2F7/2 electric-octupole transition under conditions where the light shift is much larger than the excitation linewidth, which is in the Hertz range. The experiments demonstrate a suppression of the light shift by four orders of magnitude and an immunity against its fluctuations.

  20. Generalized Ramsey excitation scheme with suppressed light shift.

    Science.gov (United States)

    Huntemann, N; Lipphardt, B; Okhapkin, M; Tamm, Chr; Peik, E; Taichenachev, A V; Yudin, V I

    2012-11-21

    We experimentally investigate a recently proposed optical excitation scheme V. I. Yudin et al. [Phys. Rev. A 82, 011804(R) (2010)] that is a generalization of Ramsey's method of separated oscillatory fields and consists of a sequence of three excitation pulses. The pulse sequence is tailored to produce a resonance signal that is immune to the light shift and other shifts of the transition frequency that are correlated with the interaction with the probe field. We investigate the scheme using a single trapped ^{171}Yb^{+} ion and excite the highly forbidden (2)S(1/2) - (2)F(7/2) electric-octupole transition under conditions where the light shift is much larger than the excitation linewidth, which is in the hertz range. The experiments demonstrate a suppression of the light shift by four orders of magnitude and an immunity against its fluctuations.

  1. Chemical Emergencies

    Science.gov (United States)

    When a hazardous chemical has been released, it may harm people's health. Chemical releases can be unintentional, as in the case of an ... the case of a terrorist attack with a chemical weapon. Some hazardous chemicals have been developed by ...

  2. Electrically assisted water shift reaction

    Energy Technology Data Exchange (ETDEWEB)

    Czernichowski, A. [Universite d`Orleans (France); Meguernes, K. [Universite de Tizi-Ouzou (Algeria)

    1995-07-01

    GlidArc-type plasma assisted water shift process of CO to H{sub 2} can be performed at atmospheric pressure without any solid catalyst and at low ({le} 415{degrees}C) temperatures in a bench-scale 1.5 kW, 1.35 l reactor with 6 knife-shaped steel electrodes for the space velocity of the order of 1000 h{sup -1}. Some 18 to 45% of CO-to-H{sub 2} shift rates are obtained for initial H{sub 2}O/CO = 0.93 to 2.7 mol/mol inputs.

  3. Thermal momentum distribution from shifted boundary conditions

    CERN Document Server

    Giusti, Leonardo

    2011-01-01

    At finite temperature the distribution of the total momentum is an observable characterizing the thermal state of a field theory, and its cumulants are related to thermodynamic potentials. In a relativistic system at zero chemical potential, for instance, the thermal variance of the total momentum is a direct measure of the entropy. We relate the generating function of the cumulants to the ratio of a path integral with properly shifted boundary conditions in the compact direction over the ordinary partition function. In this form it is well suited for Monte-Carlo evaluation, and the cumulants can be extracted straightforwardly. We test the method in the SU(3) Yang--Mills theory, and obtain the entropy density at three different temperatures.

  4. Group Chemical Changes and Physical Property Correlations in Refining of Lube Base Stocks. Ir and Nmr Spectroscopy Corrélations entre les propriétés physiques et les changements de composition chimique au cours du raffinage des huiles de base. Spectrométrie infra rouge et résonance magnétique nucléaire

    OpenAIRE

    Singh H.; Gulati I. B.

    2006-01-01

    Changes occurring in the chemical composition of lubricating oil base stocks with different degreeand typeof refining have been investigated by IR and NMR spectroscopy. Significant conclusions about the chemical composition have been reached through the study of structural parameters. Correlations between molecular parameters such as aromaticity , average number of carbon atoms per alkyl substituentand the Viscosity Indexof base oils are reported. The term degree of refininghas been assigned ...

  5. 术前颈椎曲度与椎管扩大成形术后脊髓后移程度及疗效的相关性%Correlation between cervical curvature and spinal cord shift, surgical outcome after expansive open-door laminoplasty

    Institute of Scientific and Technical Information of China (English)

    朱继超; 刘晓光; 刘忠军; 姜亮; 韦峰; 于淼; 吴奉梁

    2013-01-01

    cervical curvature after expansive open-door laminoplasty for cervical myelopathy,and to investigate the relationship between cervical curvature and spinal cord shift.Methods:63 cases of cervical myelopathy undergoing traditional expansive open-door laminoplasty between January 2005 and December 2011 were reviewed retrospectively,the pathogenesis included cervical spondylotic myelopathy(26 cases),ossification of posterior longitudinal ligament(OPLL,20 cases) and developmental cervical spinal stenosis(17 cases).Traditional expansive open-door laminoplasty was performed because of multisegmental disc disease,multilevel OPLL or developmental cervical stenosis.All cases were divided into three groups according to the cervical curvature:the kyphosis group(n=16),the straight group(n=18) and the normal alignment group(n=29).The posterior shift of center of spinal cord(PCS) at each level of laminoplasty(C3-C7) was measured and calculated through the midsagittal images of MRI T2-weighted before and after surgery.Statistic analysis was performed to analyze the difference of PCS at each level (C3-C7) among three groups.The neurofunction for each patient was estimated by using the Japanese Orthopedic Association(JOA) score before surgery and at final follow-up,and the JOA recovery rate was calculated.Statistic analysis was performed to analyze the difference of the JOA recovery rate at final follow-up among three groups.Results:There was no statistical difference in the age,sex ratio,duration of symptoms,entity,follow-up time or the preoperative JOA score(P>0.05).Posterior migration of spinal cord was observed in all three groups,and there was no significant difference with respect to the mean PCS at C3-C7 level among three groups(P>0.05).The mean follow-up was 47±24(range 15-90) months,and the mean JOA recovery rate at final follow-up of each group was 59.81%,69.25% and 54.44% respectively,which showed no statistical difference(P>0.05).No linear correlation was found

  6. The Shift Needed for Sustainability

    Science.gov (United States)

    Smith, Peter A. C.; Sharicz, Carol

    2011-01-01

    Purpose: The purpose of this action research is to begin to assess to what extent organizations have in practice begun to make the shift towards triple bottom line (TBL) sustainability. Design/methodology/approach: A definition of TBL sustainability is provided, and key elements of TBL sustainability considered necessary to success are identified…

  7. Wavelength-shifted Cherenkov radiators

    Science.gov (United States)

    Krider, E. P.; Jacobson, V. L.; Pifer, A. E.; Polakos, P. A.; Kurz, R. J.

    1976-01-01

    The scintillation and Cherenkov responses of plastic Cherenkov radiators containing different wavelength-shifting fluors in varying concentrations have been studied in beams of low energy protons and pions. For cosmic ray applications, where large Cherenkov to scintillation ratios are desired, the optimum fluor concentrations are 0.000025 by weight or less.

  8. Anthropometric changes and fluid shifts

    Science.gov (United States)

    Thornton, W. E.; Hoffler, G. W.; Rummel, J. A.

    1974-01-01

    Several observations of body size, shape, posture, and configuration were made to document changes resulting from direct effects of weightlessness during the Skylab 4 mission. After the crewmen were placed in orbit, a number of anatomical and anthropometric changes occurred including a straightening of the thoracolumbar spine, a general decrease in truncal girth, and an increase in height. By the time of the earliest in-flight measurement on mission day 3, all crewmen had lost more than two liters of extravascular fluid from the calf and thigh. The puffy facies, the bird legs effect, the engorgement of upper body veins, and the reduced volume of lower body veins were all documented with photographs. Center-of-mass measurements confirmed a fluid shift cephalad. This shift remained throughout the mission until recovery, when a sharp reversal occurred; a major portion of the reversal was completed in a few hours. The anatomical changes are of considerable scientific interest and of import to the human factors design engineer, but the shifts of blood and extravascular fluid are of more consequence. It is hypothesized that the driving force for the fluid shift is the intrinsic and unopposed lower limb elasticity that forces venous blood and then other fluid cephalad.

  9. Size-Dependent Raman Shifts for nanocrystals.

    Science.gov (United States)

    Gao, Yukun; Zhao, Xinmei; Yin, Penggang; Gao, Faming

    2016-04-22

    Raman spectroscopy is a very sensitive tool for probing semiconductor nanocrystals. The underlying mechanism behind the size-dependent Raman shifts is still quite controversial. Here we offer a new theoretical method for the quantum confinement effects on the Raman spectra of semiconductor nanocrystals. We propose that the shift of Raman spectra in nanocrystals can result from two overlapping effects: the quantum effect shift and surface effect shift. The quantum effect shift is extracted from an extended Kubo formula, the surface effect shift is determined via the first principles calculations. Fairly good prediction of Raman shifts can be obtained without the use of any adjustable parameter. Closer analysis shows that the size-dependent Raman shifts in Si nanocrystals mainly result from the quantum effect shifts. For nanodiamond, the proportion of surface effect shift in Raman shift is up to about 40%. Such model can also provide a good baseline for using Raman spectroscopy as a tool to measure size.

  10. Nanofiltration and sensing of picomolar chemical residues in aqueous solution using an optical porous resonator in a microelectrofluidic channel

    Science.gov (United States)

    Huang, Lei; Guo, Zhixiong

    2012-02-01

    For the first time the use of a porous microresonator placed in a microelectrofluidic system for integrated functions of nanofiltration and sensing of small biomolecules and chemical analytes in extremely dilute solution was proposed and investigated. As an example, aminoglycosides in drug residues in food and livestock products were considered as the trace chemical analyte. The filtration process of the charged analyte in aqueous solution driven by an applied electrical field and the accompanying optical whispering-gallery modes in the resonator are modeled. The dynamic process of adsorption and desorption of the analyte onto the porous matrix is studied. Deposition of the analyte inside the porous structure will alter the material refractive index of the resonator, and thus induce an optical resonance frequency shift. By measuring the optical frequency shift, the analyte concentration as well as the absorption/desorption process can be analyzed. Through an intensive numerical study, a correlation between the frequency shift and the analyte concentration and the applied electrical voltage gradient was obtained. This reveals a linear relationship between the resonance frequency shift and the analyte concentration. The applied electrical voltage substantially enhances the filtration capability and the magnitude of the optical frequency shift, pushing the porous resonator-based sensor to function at the extremely dilute picomolar concentration level for small bio/chemical molecules down to the sub-nanometer scale. Moreover, use of the second-order whispering-gallery mode is found to provide better sensitivity compared with the first-order mode.

  11. Decoding covert shifts of attention induced by ambiguous visuospatial cues

    Directory of Open Access Journals (Sweden)

    Romain eTrachel

    2015-06-01

    Full Text Available Simple and unambiguous visual cues (e.g. an arrow can be used to trigger covert shifts of visual attention away from the center of gaze. The processing of visual stimuli is enhanced at the attended location. Covert shifts of attention modulate the power of cerebral oscillations in the alpha band over parietal and occipital regions. These modulations are sufficiently robust to be decoded on a single trial basis from electro-encephalography (EEG signals. It is often assumed that covert attention shifts are under voluntary control, and also occur in more natural and complex environments, but there is no direct evidence to support this assumption. We address this important issue by using random-dot stimuli to cue one of two opposite locations, where a visual target is presented. We contrast two conditions in which the random-dot motion is either predictive of the target location or contains ambiguous information. Behavioral results show attention shifts in anticipation of the visual target, in both conditions. In addition, these attention shifts involve similar neural sources, and the EEG can be decoded on a single trial basis. These results shed a new light on the behavioral and neural correlates of visuospatial attention, with implications for Brain-Computer Interfaces (BCI based on covert attention shifts.

  12. Looping through the Lamb Shift

    Energy Technology Data Exchange (ETDEWEB)

    Hazi, A U

    2007-02-06

    Sometimes in science, a small measurement can have big ramifications. For a team of Livermore scientists, such was the case when they measured a small shift in the spectrum of extremely ionized atoms of uranium. The measurement involves the Lamb shift, a subtle change in the energy of an electron orbiting an atom's nucleus. The precision of the Livermore result was 10 times greater than that of existing measurements, making it the best measurement to date of a complicated correction to the simplest quantum description of how atoms behave. The measurement introduces a new realm in the search for deviations between the theory of quantum electrodynamics (QED), which is an extension of quantum mechanics, and the real world. Such deviations, if discovered, would have far-reaching consequences, indicating that QED is not a fundamental theory of nature.

  13. Lamb shift in muonic deuterium

    Energy Technology Data Exchange (ETDEWEB)

    Gorchtein, Mikhail; Vanderhaeghen, Marc [Institut für Kernphysik, Universität Mainz, 55128 Mainz (Germany); Carlson, Carl E. [Department of Physics, College of William and Mary, Williamsburg, Virginia 23187 (United States)

    2013-11-07

    We consider the two-photon exchange contribution to the 2P-2S Lamb shift in muonic deuterium in the framework of forward dispersion relations. The dispersion integrals are evaluated with minimal model dependence using experimental data on elastic deuteron form factors and inelastic electron-deuteron scattering, both in the quasielastic and hadronic range. The subtraction constant that is required to ensure convergence of the dispersion relation for the forward Compton amplitude T{sub 1} (ν,Q{sup 2}) is related to the deuteron magnetic polarizability β(Q{sup 2}) and represents the main source of uncertainty in our analysis. We obtain for the Lamb shift ΔE{sub 2P-2S} = 1.620±0.190 meV and discuss ways to further reduce this uncertainty.

  14. Anthropometric changes and fluid shifts

    Science.gov (United States)

    Thornton, W. E.; Hoffler, G. W.; Rummel, J. A.

    1977-01-01

    In an effort to obtain the most comprehensive and coherent picture of changes under weightlessness, a set of measurements on Skylab 2 was initiated and at every opportunity, additional studies were added. All pertinent information from ancillary sources were gleaned and collated. On Skylab 2, the initial anthropometric studies were scheduled in conjunction with muscle study. A single set of facial photographs was made in-flight. Additional measurements were made on Skylab 3, with photographs and truncal and limb girth measurements in-flight. Prior to Skylab 4, it was felt there was considerable evidence for large and rapid fluid shifts, so a series of in-flight volume and center of mass measurements and infrared photographs were scheduled to be conducted in the Skylab 4 mission. A number of changes were properly documented for the first time, most important of which were the fluid shifts. The following description of Skylab anthropometrics address work done on Skylab 4 primarily.

  15. Transformation of Image Positions, Rotations, and Sizes into Shift Parameters

    DEFF Research Database (Denmark)

    Skov Jensen, A.; Lindvold, L.; Rasmussen, E.

    1987-01-01

    An optical image processing system is described that converts orientation and size to shift properties and simultaneously preserves the positional information as a shift. The system is described analytically and experimentally. The transformed image can be processed further with a classical...... correlator working with a rotational and size-invariant. multiplexed match filter. An optical robot vision system designed on this concept would be able to look at several objects simultaneously and determine their shape, size, orientation, and position with two measurements on the input scene at different...

  16. New Thermodynamic Paradigm of Chemical Equilibria

    CERN Document Server

    Zilbergleyt, B

    2011-01-01

    The paper presents new thermodynamic paradigm of chemical equilibrium, setting forth comprehensive basics of Discrete Thermodynamics of Chemical Equilibria (DTd). Along with previous results by the author during the last decade, this work contains also some new developments of DTd. Based on the Onsager's constitutive equations, reformulated by the author thermodynamic affinity and reaction extent, and Le Chatelier's principle, DTd brings forward a notion of chemical equilibrium as a balance of internal and external thermodynamic forces (TdF), acting against a chemical system. Basic expression of DTd is the chemical system logistic map of thermodynamic states that ties together energetic characteristics of chemical reaction, occurring in the system, the system shift from "true" thermodynamic equilibrium (TdE), and causing that shift external thermodynamic forces. Solutions to the basic map are pitchfork bifurcation diagrams in coordinates "shift from TdE - growth factor (or TdF)"; points, corresponding to the ...

  17. Debt Shifting and Ownership Structure

    OpenAIRE

    Dirk Schindler; Guttorm Schjelderup

    2011-01-01

    Previous theoretical studies on the debt shifting behavior of multinationals have assumed affiliates of multinationals to be wholly owned. We develop a model that allows a multinational firm to determine both the leverage and ownership structure in affiliates endogenously. A main finding is that affiliates with minority owners have less debt than wholly owned affiliates and therefore a less tax efficient financing structure. This is due to an externality that arises endogenously in our model,...

  18. Lamb shift in muonic deuterium

    CERN Document Server

    Carboni, G

    1973-01-01

    The author has calculated the various contributions to 2s-2p splitting for muonic deuterium. An instantaneous potential is constructed between the muon and the nucleus. Except for the Coulomb potential, all the remaining terms are treated as a perturbation. The effects taken into account are fine structure, magnetic and electric hyperfine structure, muonic Lamb shift, vacuum polarisation, nuclear polarisation and nuclear size. (11 refs).

  19. Frequency shifts in gravitational resonance spectroscopy

    CERN Document Server

    Baeßler, S; Pignol, G; Protasov, K V; Rebreyend, D; Kupriyanova, E A; Voronin, A Yu

    2015-01-01

    Quantum states of ultracold neutrons in the gravitational field are to be characterized through gravitational resonance spectroscopy. This paper discusses systematic effects that appear in the spectroscopic measurements. The discussed frequency shifts, which we call Stern-Gerlach shift, interference shift, and spectator state shift, appear in conceivable measurement schemes and have general importance. These shifts have to be taken into account in precision experiments.

  20. Shift work and endocrine disorders.

    Science.gov (United States)

    Ulhôa, M A; Marqueze, E C; Burgos, L G A; Moreno, C R C

    2015-01-01

    The objective of this review was to investigate the impact of shift and night work on metabolic processes and the role of alterations in the sleep-wake cycle and feeding times and environmental changes in the occurrence of metabolic disorders. The literature review was performed by searching three electronic databases for relevant studies published in the last 10 years. The methodological quality of each study was assessed, and best-evidence synthesis was applied to draw conclusions. The literature has shown changes in concentrations of melatonin, cortisol, ghrelin, and leptin among shift workers. Melatonin has been implicated for its role in the synthesis and action of insulin. The action of this hormone also regulates the expression of transporter glucose type 4 or triggers phosphorylation of the insulin receptor. Therefore, a reduction in melatonin can be associated with an increase in insulin resistance and a propensity for the development of diabetes. Moreover, shift work can negatively affect sleep and contribute to sedentarism, unhealthy eating habits, and stress. Recent studies on metabolic processes have increasingly revealed their complexity. Physiological changes induced in workers who invert their activity-rest cycle to fulfill work hours include disruptions in metabolic processes.

  1. Shift Work and Endocrine Disorders

    Directory of Open Access Journals (Sweden)

    M. A. Ulhôa

    2015-01-01

    Full Text Available The objective of this review was to investigate the impact of shift and night work on metabolic processes and the role of alterations in the sleep-wake cycle and feeding times and environmental changes in the occurrence of metabolic disorders. The literature review was performed by searching three electronic databases for relevant studies published in the last 10 years. The methodological quality of each study was assessed, and best-evidence synthesis was applied to draw conclusions. The literature has shown changes in concentrations of melatonin, cortisol, ghrelin, and leptin among shift workers. Melatonin has been implicated for its role in the synthesis and action of insulin. The action of this hormone also regulates the expression of transporter glucose type 4 or triggers phosphorylation of the insulin receptor. Therefore, a reduction in melatonin can be associated with an increase in insulin resistance and a propensity for the development of diabetes. Moreover, shift work can negatively affect sleep and contribute to sedentarism, unhealthy eating habits, and stress. Recent studies on metabolic processes have increasingly revealed their complexity. Physiological changes induced in workers who invert their activity-rest cycle to fulfill work hours include disruptions in metabolic processes.

  2. Solvent effects on 15N NMR coordination shifts.

    Science.gov (United States)

    Kleinmaier, Roland; Arenz, Sven; Karim, Alavi; Carlsson, Anna-Carin C; Erdélyi, Máté

    2013-01-01

    (15)N NMR chemical shift became a broadly utilized tool for characterization of complex structures and comparison of their properties. Despite the lack of systematic studies, the influence of solvent on the nitrogen coordination shift, Δ(15)N(coord), was hitherto claimed to be negligible. Herein, we report the dramatic impact of the local environment and in particular that of the interplay between solvent and substituents on Δ(15)N(coord). The comparative study of CDCl(3) and CD(3)CN solutions of silver(I)-bis(pyridine) and silver(I)-bis(pyridylethynyl)benzene complexes revealed the strong solvent dependence of their (15)N NMR chemical shift, with a solvent dependent variation of up to 40 ppm for one and the same complex. The primary influence of the effect of substituent and counter ion on the (15)N NMR chemical shifts is rationalized by corroborating Density-Functional Theory (nor discrete Fourier transform) calculations on the B3LYP/6-311 + G(2d,p)//B3LYP/6-31G(d) level. Cooperative effects have to be taken into account for a comprehensive description of the coordination shift and thus the structure of silver complexes in solution. Our results demonstrate that interpretation of Δ(15)N(coord) in terms of coordination strength must always consider the solvent and counter ion. The comparable magnitude of Δ(15)N(coord) for reported transition metal complexes makes the principal findings most likely general for a broad scale of complexes of nitrogen donor ligands, which are in frequent use in modern organometallic chemistry.

  3. Direct Monte Carlo simulation of the chemical equilibrium composition of detonation products

    Energy Technology Data Exchange (ETDEWEB)

    Shaw, M.S.

    1993-06-01

    A new Monte Carlo simulation method has been developed by the author which gives the equilibrium chemical composition of a molecular fluid directly. The usual NPT ensemble (isothermal-isobaric) is implemented with N being the number of atoms instead of molecules. Changes in chemical composition are treated as correlated spatial moves of atoms. Given the interaction potentials between molecular products, ``exact`` EOS points including the equilibrium chemical composition can be determined from the simulations. This method is applied to detonation products at conditions in the region near the Chapman- Jouget state. For the example of NO, it is shown that the CJ detonation velocity can be determined to a few meters per second. A rather small change in cross potentials is shown to shift the chemical equilibrium and the CJ conditions significantly.

  4. Score Correlation

    OpenAIRE

    Fabián, Z. (Zdeněk)

    2010-01-01

    In this paper, we study a distribution-dependent correlation coefficient based on the concept of scalar score. This new measure of association of continuous random variables is compared by means of simulation experiments with the Pearson, Kendall and Spearman correlation coefficients.

  5. Cross-correlation beamforming

    Science.gov (United States)

    Ruigrok, Elmer; Gibbons, Steven; Wapenaar, Kees

    2016-10-01

    An areal distribution of sensors can be used for estimating the direction of incoming waves through beamforming. Beamforming may be implemented as a phase-shifting and stacking of data recorded on the different sensors (i.e., conventional beamforming). Alternatively, beamforming can be applied to cross-correlations between the waveforms on the different sensors. We derive a kernel for beamforming cross-correlated data and call it cross-correlation beamforming (CCBF). We point out that CCBF has slightly better resolution and aliasing characteristics than conventional beamforming. When auto-correlations are added to CCBF, the array response functions are the same as for conventional beamforming. We show numerically that CCBF is more resilient to non-coherent noise. Furthermore, we illustrate that with CCBF individual receiver-pairs can be removed to improve mapping to the slowness domain. An additional flexibility of CCBF is that cross-correlations can be time-windowed prior to beamforming, e.g., to remove the directionality of a scattered wavefield. The observations on synthetic data are confirmed with field data from the SPITS array (Svalbard). Both when beamforming an earthquake arrival and when beamforming ambient noise, CCBF focuses more of the energy to a central beam. Overall, the main advantage of CCBF is noise suppression and its flexibility to remove station pairs that deteriorate the signal-related beampower.

  6. Giant Goos-H\\"anchen shift in Scattering: the role of interfering Localized Plasmon modes

    CERN Document Server

    Soni, J; Gupta, S Dutta; Banerjee, A; Ghosh, N

    2014-01-01

    The longitudinal and the transverse beam shifts, namely, the Goos-H\\"anchen (GH) and the Spin-Hall (SH) shifts are usually observed at planar interfaces. It has recently been shown that the transverse SH shift may also arise due to scattering of plane waves. Here, we show that analogous in-plane (longitudinal) shift also exist in scattering of plane waves from micro/nano systems. We study both the GH and the SH shifts in plasmonic metal nanoparticles/ nanostructures and dielectric micro-particles employing a unified framework that utilizes the transverse components of the Poynting vector of the scattered wave. The results demonstrate that interference of neighboring resonance modes in plasmonic nanostructures (e.g., electric dipolar and quadrupolar modes in metal spheres) leads to giant enhancement of GH shift in scattering from such systems. We also unravel interesting correlations between these shifts with the polarimetry parameters, diattenuation and retardance.

  7. Giant Goos-Hänchen shift in scattering: the role of interfering localized plasmon modes

    Science.gov (United States)

    Soni, J.; Mansha, S.; Dutta Gupta, S.; Banerjee, A.; Ghosh, N.

    2014-07-01

    The longitudinal and the transverse beam shifts, namely, the Goos-H\\"anchen (GH) and the Spin-Hall (SH) shifts are usually observed at planar interfaces. It has recently been shown that the transverse SH shift may also arise due to scattering of plane waves. Here, we show that analogous in-plane (longitudinal) shift also exist in scattering of plane waves from micro/nano systems. We study both the GH and the SH shifts in plasmonic metal nanoparticles/ nanostructures and dielectric micro-particles employing a unified framework that utilizes the transverse components of the Poynting vector of the scattered wave. The results demonstrate that interference of neighboring resonance modes in plasmonic nanostructures (e.g., electric dipolar and quadrupolar modes in metal spheres) leads to giant enhancement of GH shift in scattering from such systems. We also unravel interesting correlations between these shifts with the polarimetry parameters, diattenuation and retardance.

  8. 当归-桃仁药对配伍特点及其效应物质基础研究%Study on the correlation of chemical constituents and activities of Radix Angelicae Sinensis and Semen Persicae

    Institute of Scientific and Technical Information of China (English)

    刘立; 段金廒; 唐于平; 钱大玮; 史旭芹; 宿树兰; 胡莹

    2011-01-01

    Objective: Study on the correlation of chemical constituents and activities in different proportions of Radix Angelicae Sinensis and Semen Persicae. Methods: Data mining technology was applied on prescription to screening the proportions of Radix Angelicae Sinensis and Semen Persicae. HPLC determined the changes of the contents of amygdalin, chlorogenic acid, caffeic acid and ferulic acid in the single and mixed decoction of Radix Angelicae Sinensis and Semen Persicae. The experiments of thrombin time, anti-platelet aggregation and scavenging DPPH were evaluated the activities. Results: The top 10 proportions of Radix Angelicae Sinensis and Semen Persicae were screening. The contents of amygdalin, chlorogenic acid, caffeic acid and ferulic acid were higher than the single decoction of Radix Angelicae Sinensis and Semen Persicae. Thrombin time was prolonged, anti-platelet aggregation was increased and the activity of scavenging DPPH was enhanced when compared to the same drug dosage of the single decoction of Semen Persicae. The activity of anti-platelet aggregation was also increased when compared to the same drug dosage of the single decoction of Radix Angelicae Sinensis. Conclusion: Mixed decoction of Radix Angelicae Sinensis and Semen Persicae was rationality. The change of chemical constituents and activities has some correlation, but different proportions have no conspicuous variability.%目的:探讨当归-桃仁药对不同配比的应用特点及其效应物质基础.方法:基于自建的中医方剂数据库,采用关联规则分析方法,挖掘归纳出当归-桃仁药对在方剂中的配伍特点;采用HPLC法分析当归-桃仁药对共煎液与单煎液不同配比中苦杏仁苷、绿原酸、咖啡酸、阿魏酸的含量变化;采用凝血时间、抑制血小板聚集和清除DPPH自由基实验评价配伍效应及其作用特点.结果:挖掘归纳出当归-桃仁药对在方剂中的配伍特点及其出现频度;实验结果表明当

  9. Correlation ion mobility spectroscopy

    Science.gov (United States)

    Pfeifer, Kent B.; Rohde, Steven B.

    2008-08-26

    Correlation ion mobility spectrometry (CIMS) uses gating modulation and correlation signal processing to improve IMS instrument performance. Closely spaced ion peaks can be resolved by adding discriminating codes to the gate and matched filtering for the received ion current signal, thereby improving sensitivity and resolution of an ion mobility spectrometer. CIMS can be used to improve the signal-to-noise ratio even for transient chemical samples. CIMS is especially advantageous for small geometry IMS drift tubes that can otherwise have poor resolution due to their small size.

  10. Redox regime shifts in microbially mediated biogeochemical cycles

    Science.gov (United States)

    Bush, T.; Butler, I. B.; Free, A.; Allen, R. J.

    2015-06-01

    Understanding how the Earth's biogeochemical cycles respond to environmental change is a prerequisite for the prediction and mitigation of the effects of anthropogenic perturbations. Microbial populations mediate key steps in these cycles, yet they are often crudely represented in biogeochemical models. Here, we show that microbial population dynamics can qualitatively affect the response of biogeochemical cycles to environmental change. Using simple and generic mathematical models, we find that nutrient limitations on microbial population growth can lead to regime shifts, in which the redox state of a biogeochemical cycle changes dramatically as the availability of a redox-controlling species, such as oxygen or acetate, crosses a threshold (a "tipping point"). These redox regime shifts occur in parameter ranges that are relevant to the present-day sulfur cycle in the natural environment and the present-day nitrogen cycle in eutrophic terrestrial environments. These shifts may also have relevance to iron cycling in the iron-containing Proterozoic and Archean oceans. We show that redox regime shifts also occur in models with physically realistic modifications, such as additional terms, chemical states, or microbial populations. Our work reveals a possible new mechanism by which regime shifts can occur in nutrient-cycling ecosystems and biogeochemical cycles, and highlights the importance of considering microbial population dynamics in models of biogeochemical cycles.

  11. Correlative Analysis between Several Chemical Substances and Chinese Chives Cultivar Resistance to Bradysia odoriphage Yang et Zhang%几种生化物质与韭菜抗迟眼蕈蚊的相关分析

    Institute of Scientific and Technical Information of China (English)

    潘敏; 杨建平; 曹安堂

    2011-01-01

    选用20个具有不同迟眼蕈蚊抗性的韭菜栽培品种,在迟眼蕈蚊发生高峰期对韭菜叶组织中的粗纤维、芳香油、可溶性蛋白、可溶性糖、色素、叶绿素a及游离氨基酸含量进行了测定,通过与韭菜抗虫性评价指标(虫口密度、受害植株比例和叶片被害指数)的相关分析,进行了韭菜生化物质含量与韭菜抗虫性的相互关系研究.结果表明,与感虫品种相比,抗虫品种中均有较低的芳香油、可溶性糖和游离氨基酸含量;抗虫品种较感虫品种有较高的粗纤维、可溶性蛋白、色素和叶绿素a含量.基于相关分析和逐步回归分析的韭菜抗虫性和生化指标间关系分析表明:芳香油、可溶性蛋白和游离氨基酸等3个生化指标与韭菜品种抗虫性有较为紧密的关系,其中又以芳香油含量与韭菜抗虫性的关系最为密切.%Twenty Chinese chives cultivars that showed different resistance to Bradysia odoriphage were selected to study the correlations between the pest resistance ( based on 3 pest resistant index: pest density, percentage of infected plants and leaf suffering index ) and the content of several physiological chemical substances, including coarse-fiber, naphtha, soluble sugar, soluble protein, pigment, chlorophl-a and dissociative amino acids. The results showed that the contents of naphths, soluble sugar and dissociative amino acids in the resistant cultivars appeared with lower content than those of the infective ones. But the contents of coarse-fiber, soluble protein, pigment and chlorophl-a in the resistant cultivars showed higher values than the infective ones. The results of correlative analysis showed that the contents of naphtha, soluble protein and dissociative amino acids displayed distinct correlations with the level of pest resistance. And the results of regression analysis also revealed that the content of naphtha might be the most important factor for the pest resistance.

  12. Correlation exploration of metabolic and genomic diversity in rice

    Directory of Open Access Journals (Sweden)

    Shinozaki Kazuo

    2009-12-01

    Full Text Available Abstract Background It is essential to elucidate the relationship between metabolic and genomic diversity to understand the genetic regulatory networks associated with the changing metabolo-phenotype among natural variation and/or populations. Recent innovations in metabolomics technologies allow us to grasp the comprehensive features of the metabolome. Metabolite quantitative trait analysis is a key approach for the identification of genetic loci involved in metabolite variation using segregated populations. Although several attempts have been made to find correlative relationships between genetic and metabolic diversity among natural populations in various organisms, it is still unclear whether it is possible to discover such correlations between each metabolite and the polymorphisms found at each chromosomal location. To assess the correlative relationship between the metabolic and genomic diversity found in rice accessions, we compared the distance matrices for these two "omics" patterns in the rice accessions. Results We selected 18 accessions from the world rice collection based on their population structure. To determine the genomic diversity of the rice genome, we genotyped 128 restriction fragment length polymorphism (RFLP markers to calculate the genetic distance among the accessions. To identify the variations in the metabolic fingerprint, a soluble extract from the seed grain of each accession was analyzed with one dimensional 1H-nuclear magnetic resonance (NMR. We found no correlation between global metabolic diversity and the phylogenetic relationships among the rice accessions (rs = 0.14 by analyzing the distance matrices (calculated from the pattern of the metabolic fingerprint in the 4.29- to 0.71-ppm 1H chemical shift and the genetic distance on the basis of the RFLP markers. However, local correlation analysis between the distance matrices (derived from each 0.04-ppm integral region of the 1H chemical shift against genetic

  13. On the use of pseudocontact shifts in the structure determination of metalloproteins.

    Science.gov (United States)

    Jensen, Malene Ringkjøbing; Hansen, D Flemming; Ayna, Umit; Dagil, Robert; Hass, Mathias A S; Christensen, Hans E M; Led, Jens J

    2006-03-01

    The utility of pseudocontact shifts in the structure refinement of metalloproteins has been evaluated using a native, paramagnetic Cu(2+) metalloprotein, plastocyanin from Anabaena variabilis (A.v.), as a model protein. First, the possibility of detecting signals of nuclei spatially close to the paramagnetic metal ion is investigated using the WEFT pulse sequence in combination with the conventional TOCSY and (1)H-(15)N HSQC sequences. Second, the importance of the electrical charge of the metal ion for the determination of correct pseudocontact shifts from the obtained chemical shifts is evaluated. Thus, using both the Cu(+) plastocyanin and Cd(2+)-substituted plastocyanin as the diamagnetic references, it is found that the Cd(2+)-substituted protein with the same electrical charge of the metal ion as the paramagnetic Cu(2+) plastocyanin provides the most appropriate diamagnetic reference signals. Third, it is found that reliable pseudocontact shifts cannot be obtained from the chemical shifts of the (15)N nuclei in plastocyanin, most likely because these shifts are highly dependent on even minor differences in the structure of the paramagnetic and diamagnetic proteins. Finally, the quality of the obtained (1)H pseudocontact shifts, as well as the possibility of improving the accuracy of the obtained structure, is demonstrated by incorporating the shifts as restraints in a refinement of the solution structure of A.v. plastocyanin. It is found that incorporation of the pseudocontact shifts enhances the precision of the structure in regions with only few NOE restraints and improves the accuracy of the overall structure.

  14. [Essentials of pharmacophylogeny: knowledge pedigree, epistemology and paradigm shift].

    Science.gov (United States)

    Hao, Da-cheng; Xiao, Pei-gen; Liu, Li-wei; Peng, Yong; He, Chun-nian

    2015-09-01

    Chinese materia medica resource (CMM resource) is the foundation of the development of traditional Chinese medicine. In the study of sustainable utilization of CMM resource, adopting innovative theory and method to find new CMM resource is one of hotspots and always highlighted. Pharmacophylogeny interrogates the phylogenetic relationship of medicinal organisms (especially