WorldWideScience

Sample records for chemical shift correlation

  1. Mineral Moessbauer spectroscopy: correlations between chemical shift and quadrupole splitting parameters

    International Nuclear Information System (INIS)

    The variety of coordination numbers, symmetries, distortions and ligand environments in thermally-stable iron-bearing minerals provide wide ranges of chemical shift (δ) and quadrupole splitting (Δ) parameters, which serve to characterize the crystal chemistries and site occupancies of Fe2+ and Fe3+ ions in minerals of terrestrial and extraterrestrial origins. Correlations between ferrous and ferric chemical shifts enable thermally-induced electron delocalization behavior in mixed-valence Fe2+-Fe3+ minerals to be identified, while chemical shift versus quadrupole splitting correlations serve to identify nanophase ferric oxides and oxyhydroxides in oxidized minerals and in meteorites subjected to aqueous oxidation before and after they arrived on Earth. (orig.)

  2. 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...... use random coil peptides containing glutamine instead of glycine to determine the random coil chemical shifts and the neighbor correction factors. The resulting correction factors correlate to changes in the populations of the major wells in the Ramachandran plot, which demonstrates that changes...... 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...

  3. 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.

  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. 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

  8. 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.

  9. 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).

  10. 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

  11. 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.

  12. Accessible surface area from NMR chemical shifts

    International Nuclear Information System (INIS)

    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

  13. A Short History of Three Chemical Shifts

    Science.gov (United States)

    Nagaoka, Shin-ichi

    2007-01-01

    A short history of chemical shifts in nuclear magnetic resonance (NMR), electron spectroscopy for chemical analysis (ESCA) and Mossbauer spectroscopy, which are useful for chemical studies, is described. The term chemical shift is shown to have originated in the mistaken assumption that nuclei of a given element would all undergo resonance at the…

  14. Dynamics-based selective 2D {sup 1}H/{sup 1}H chemical shift correlation spectroscopy under ultrafast MAS conditions

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-05-28

    Dynamics plays important roles in determining the physical, chemical, and functional properties of a variety of chemical and biological materials. However, a material (such as a polymer) generally has mobile and rigid regions in order to have high strength and toughness at the same time. Therefore, it is difficult to measure the role of mobile phase without being affected by the rigid components. Herein, we propose a highly sensitive solid-state NMR approach that utilizes a dipolar-coupling based filter (composed of 12 equally spaced 90° RF pulses) to selectively measure the correlation of {sup 1}H chemical shifts from the mobile regions of a material. It is interesting to find that the rotor-synchronized dipolar filter strength decreases with increasing inter-pulse delay between the 90° pulses, whereas the dipolar filter strength increases with increasing inter-pulse delay under static conditions. In this study, we also demonstrate the unique advantages of proton-detection under ultrafast magic-angle-spinning conditions to enhance the spectral resolution and sensitivity for studies on small molecules as well as multi-phase polymers. Our results further demonstrate the use of finite-pulse radio-frequency driven recoupling pulse sequence to efficiently recouple weak proton-proton dipolar couplings in the dynamic regions of a molecule and to facilitate the fast acquisition of {sup 1}H/{sup 1}H correlation spectrum compared to the traditional 2D NOESY (Nuclear Overhauser effect spectroscopy) experiment. We believe that the proposed approach is beneficial to study mobile components in multi-phase systems, such as block copolymers, polymer blends, nanocomposites, heterogeneous amyloid mixture of oligomers and fibers, and other materials.

  15. SAFT缔合模型关联含水体系的1H NMR%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.

  16. Probabilistic Approach to Determining Unbiased Random-coil Carbon-13 Chemical Shift Values from the Protein Chemical Shift Database

    International Nuclear Information System (INIS)

    We describe a probabilistic model for deriving, from the database of assigned chemical shifts, a set of random coil chemical shift values that are 'unbiased' insofar as contributions from detectable secondary structure have been minimized (RCCSu). We have used this approach to derive a set of RCCSu values for 13Cα and 13Cβ for 17 of the 20 standard amino acid residue types by taking advantage of the known opposite conformational dependence of these parameters. We present a second probabilistic approach that utilizes the maximum entropy principle to analyze the database of 13Cα and 13Cβ chemical shifts considered separately; this approach yielded a second set of random coil chemical shifts (RCCSmax-ent). Both new approaches analyze the chemical shift database without reference to known structure. Prior approaches have used either the chemical shifts of small peptides assumed to model the random coil state (RCCSpeptide) or statistical analysis of chemical shifts associated with structure not in helical or strand conformation (RCCSstruct-stat). We show that the RCCSmax-ent values are strikingly similar to published RCCSpeptide and RCCSstruct-stat values. By contrast, the RCCSu values differ significantly from both published types of random coil chemical shift values. The differences (RCCSpeptide-RCCSu) for individual residue types show a correlation with known intrinsic conformational propensities. These results suggest that random coil chemical shift values from both prior approaches are biased by conformational preferences. RCCSu values appear to be consistent with the current concept of the 'random coil' as the state in which the geometry of the polypeptide ensemble samples the allowed region of (φ,ψ)-space in the absence of any dominant stabilizing interactions and thus represent an improved basis for the detection of secondary structure. Coupled with the growing database of chemical shifts, this probabilistic approach makes it possible to refine

  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...

  18. Easy and unambiguous sequential assignments of intrinsically disordered proteins by correlating the backbone {sup 15}N or {sup 13}C′ chemical shifts of multiple contiguous residues in highly resolved 3D spectra

    Energy Technology Data Exchange (ETDEWEB)

    Yoshimura, Yuichi; Kulminskaya, Natalia V.; Mulder, Frans A. A., E-mail: fmulder@chem.au.dk [Aarhus University, Department of Chemistry and Interdisciplinary Nanoscience Center (iNANO) (Denmark)

    2015-02-15

    Sequential resonance assignment strategies are typically based on matching one or two chemical shifts of adjacent residues. However, resonance overlap often leads to ambiguity in resonance assignments in particular for intrinsically disordered proteins. We investigated the potential of establishing connectivity through the three-bond couplings between sequentially adjoining backbone carbonyl carbon nuclei, combined with semi-constant time chemical shift evolution, for resonance assignments of small folded and larger unfolded proteins. Extended sequential connectivity strongly lifts chemical shift degeneracy of the backbone nuclei in disordered proteins. We show here that 3D (H)N(COCO)NH and (HN)CO(CO)NH experiments with relaxation-optimized multiple pulse mixing correlate up to seven adjacent backbone amide nitrogen or carbonyl carbon nuclei, respectively, and connections across proline residues are also obtained straightforwardly. Multiple, recurrent long-range correlations with ultra-high resolution allow backbone {sup 1}H{sup N}, {sup 15}N{sup H}, and {sup 13}C′ resonance assignments to be completed from a single pair of 3D experiments.

  19. A Series of Diamagnetic Pyridine Monoimine Rhenium Complexes with Different Degrees of Metal-to-Ligand Charge Transfer: Correlating (13) C NMR Chemical Shifts with Bond Lengths in Redox-Active Ligands.

    Science.gov (United States)

    Sieh, Daniel; Kubiak, Clifford P

    2016-07-18

    A set of pyridine monoimine (PMI) rhenium(I) tricarbonyl chlorido complexes with substituents of different steric and electronic properties was synthesized and fully characterized. Spectroscopic (NMR and IR) and single-crystal X-ray diffraction analyses of these complexes showed that the redox-active PMI ligands are neutral and that the overall electronic structure is little affected by the choices of the substituent at the ligand backbone. One- and two-electron reduction products were prepared from selected starting compounds and could also be characterized by multiple spectroscopic methods and X-ray diffraction. The final product of a one-electron reduction in THF is a diamagnetic metal-metal-bonded dimer after loss of the chlorido ligand. Bond lengths in and NMR chemical shifts of the PMI ligand backbone indicate partial electron transfer to the ligand. Two-electron reduction in THF also leads to the loss of the chlorido ligand and a pentacoordinate complex is obtained. The comparison with reported bond lengths and (13) C NMR chemical shifts of doubly reduced free pyridine monoaldimine ligands indicates that both redox equivalents in the doubly reduced rhenium complex investigated here are located in the PMI ligand. With diamagnetic complexes varying over three formal reduction stages at the PMI ligand we were, for the first time, able to establish correlations of the (13) C NMR chemical shifts with the relevant bond lengths in redox-active ligands over a full redox series. PMID:27319753

  20. Random coil chemical shift for intrinsically disordered proteins

    DEFF Research Database (Denmark)

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

    2011-01-01

    Secondary chemical shift analysis is the main NMR method for detection of transiently formed secondary structure in intrinsically disordered proteins. The quality of the secondary chemical shifts is dependent on an appropriate choice of random coil chemical shifts. We report random coil chemical....... 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...

  1. 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.

  2. 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.

  3. 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.

  4. Shifting-and-Scaling Correlation Based Biclustering Algorithm.

    Science.gov (United States)

    Ahmed, Hasin Afzal; Mahanta, Priyakshi; Bhattacharyya, Dhruba Kumar; Kalita, Jugal Kumar

    2014-01-01

    The existence of various types of correlations among the expressions of a group of biologically significant genes poses challenges in developing effective methods of gene expression data analysis. The initial focus of computational biologists was to work with only absolute and shifting correlations. However, researchers have found that the ability to handle shifting-and-scaling correlation enables them to extract more biologically relevant and interesting patterns from gene microarray data. In this paper, we introduce an effective shifting-and-scaling correlation measure named Shifting and Scaling Similarity (SSSim), which can detect highly correlated gene pairs in any gene expression data. We also introduce a technique named Intensive Correlation Search (ICS) biclustering algorithm, which uses SSSim to extract biologically significant biclusters from a gene expression data set. The technique performs satisfactorily with a number of benchmarked gene expression data sets when evaluated in terms of functional categories in Gene Ontology database. PMID:26357059

  5. Sideband correlation algorithm to detect phase shift and contrast variation in temporal phase-shifting interferometry

    International Nuclear Information System (INIS)

    Phase shift error and contrast variation caused by vibration lead to a large measurement error in temporal phase-shifting interferometry (PSI). To suppress the error, a sideband correlation algorithm is proposed to detect phase shift and contrast variation. The tilt factors and translational values of phase shift are determined by analyzing the correlations of spectral sidebands of interferograms. The contrast variations are determined by detecting the modulus of the baseband and sideband correlation result. A least-squares equation with contrast compensation is established to retrieve the wavefront phase. The algorithm requires a set of temporal phase-shifting interferograms, each one also containing a moderate amount of spatial-carrier; the interferograms may have an arbitrary aperture. Simulations demonstrate the reliability, and the experiments under vibration show the practical effectiveness of the algorithm. (paper)

  6. 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 negative, indicating transmission via the hydrogen bond. In addition unusual long-range effects are seen. Structures, NMR chemical shifts and changes in nuclear shieldings upon deuteriation are calculated using DFT methods. Two-bond deuterium isotope effects on 13C chemical shifts are correlated...... with calculated OH stretching frequencies. Isotope effects on chemical shifts are calculated for systems with OH exchanged by OD. Hydrogen bond potentials are discussed. New and more soluble nitro derivatives are synthesized....

  7. 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.

  8. 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.

  9. Detection of initiation sites in protein folding of the four helix bundle ACBP by chemical shift analysis

    DEFF Research Database (Denmark)

    Modig, K.; Jürgensen, Vibeke Würtz; Lindorff-Larsen, K.;

    2007-01-01

    A simple alternative method for obtaining "random coil" chemical shifts by intrinsic referencing using the protein's own peptide sequence is presented. These intrinsic random coil backbone shifts were then used to calculate secondary chemical shifts, that provide important information on the resi......A simple alternative method for obtaining "random coil" chemical shifts by intrinsic referencing using the protein's own peptide sequence is presented. These intrinsic random coil backbone shifts were then used to calculate secondary chemical shifts, that provide important information...... on the residual secondary structure elements in the acid-denatured state of an acylcoenzyme A binding protein. This method reveals a clear correlation between the carbon secondary chemical shifts and the amide secondary chemical shifts 3-5 residues away in the primary sequence. These findings strongly suggest...... transient formation of short helix-like segments, and identify unique sequence segments important for protein folding....

  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. Chemical shifts in transition metal dithiocarbamates from infrared and X-ray photoelectron spectroscopies

    Science.gov (United States)

    Payne, R.; Magee, R. J.; Liesegang, J.

    1982-11-01

    Measurements of the IR stretching frequencies of the NC and MS bonds in transition-metal (M) dithiocarbamates show significant correlation with measurement of core level XPS chemical shifts. This is believed to be the first demonstration of such a correlation for a series of solid-phase compounds.

  12. 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.

  13. Counterion influence on chemical shifts in strychnine salts.

    Science.gov (United States)

    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 (1)H and (13)C 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. 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 with 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. PMID:23495106

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

    International Nuclear Information System (INIS)

    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 Cβ and Hβ, in agreement with observations made in Grzesiek and Bax, 1993. Based on four nuclei: Hβ, Cβ, Cα 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

  15. /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.

  16. 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......, and a bias is introduced which might result in incorrect structures. In the inferential structure determination framework, both the unknown structure and the disagreement between experimental and back-calculated data are formulated as a joint probability distribution, thus utilizing the full information...... 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...

  17. Ab Initio Prediction of 29Si-NMR Chemical Shifts

    Institute of Scientific and Technical Information of China (English)

    CHU Shidong; LI Yingxia; SONG Ni; GUAN Huashi

    2002-01-01

    The ability of several ab initio models to predict experimental 29Si-NMR chemical shift is examined. The shielding values of trimethylsilyl chloride (A), t-butyldimethylsilyl chloride (B) and allyltrimethylsilane (C) are calculated by GIAO, CSGT and IGAIM methods, using HF/6-31G*, B3LYP/6-31G*, HF/6-311+G**, B3LYP/6-311+G** and MPWlPW91/6-311+G** models respectively. The 29Si chemical shifts calculated by GIAO method using HF/6-311+G**model are highly in agreement with those obtained experimentally. All of the models above reproduce the trends of chemical shifts in all cases studied, suggesting that the models are of practical value.

  18. Pitfalls of adrenal imaging with chemical shift MRI

    International Nuclear Information System (INIS)

    Chemical shift (CS) MRI of the adrenal glands exploits the different precessional frequencies of fat and water protons to differentiate the intracytoplasmic lipid-containing adrenal adenoma from other adrenal lesions. The purpose of this review is to illustrate both technical and interpretive pitfalls of adrenal imaging with CS MRI and emphasize the importance of adherence to strict technical specifications and errors that may occur when other imaging features and clinical factors are not incorporated into the diagnosis. When performed properly, the specificity of CS MRI for the diagnosis of adrenal adenoma is over 90%. Sampling the in-phase and opposed-phase echoes in the correct order and during the same breath-hold are essential requirements, and using the first echo pair is preferred, if possible. CS MRI characterizes more adrenal adenomas then unenhanced CT but may be non-diagnostic in a proportion of lipid-poor adenomas; CT washout studies may be able to diagnose these lipid-poor adenomas. Other primary and secondary adrenal tumours and supra-renal disease entities may contain lipid or gross fat and mimic adenoma or myelolipoma. Heterogeneity within an adrenal lesion that contains intracytoplasmic lipid could be due to myelolipoma, lipomatous metaplasia of adenoma, or collision tumour. Correlation with previous imaging, other imaging features, clinical history, and laboratory investigations can minimize interpretive errors

  19. Protein backbone chemical shifts predicted from searching a database for torsion angle and sequence homology

    International Nuclear Information System (INIS)

    Chemical shifts of nuclei in or attached to a protein backbone are exquisitely sensitive to their local environment. A computer program, SPARTA, is described that uses this correlation with local structure to predict protein backbone chemical shifts, given an input three-dimensional structure, by searching a newly generated database for triplets of adjacent residues that provide the best match in φ/ψ/χ1 torsion angles and sequence similarity to the query triplet of interest. The database contains 15N, 1HN, 1Hα, 13Cα, 13Cβ and 13C' chemical shifts for 200 proteins for which a high resolution X-ray (≤2.4 A) structure is available. The relative importance of the weighting factors for the φ/ψ/χ1 angles and sequence similarity was optimized empirically. The weighted, average secondary shifts of the central residues in the 20 best-matching triplets, after inclusion of nearest neighbor, ring current, and hydrogen bonding effects, are used to predict chemical shifts for the protein of known structure. Validation shows good agreement between the SPARTA-predicted and experimental shifts, with standard deviations of 2.52, 0.51, 0.27, 0.98, 1.07 and 1.08 ppm for 15N, 1HN, 1Hα, 13Cα, 13Cβ and 13C', respectively, including outliers

  20. 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.

  1. Calculations of NMR chemical shifts with APW-based methods

    Science.gov (United States)

    Laskowski, Robert; Blaha, Peter

    2012-01-01

    We present a full potential, all electron augmented plane wave (APW) implementation of first-principles calculations of NMR chemical shifts. In order to obtain the induced current we follow a perturbation approach [Pickard and Mauri, Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.63.245101 63, 245101 (2001)] and extended the common APW + local orbital (LO) basis by several LOs at higher energies. The calculated all-electron current is represented in traditional APW manner as Fourier series in the interstitial region and with a spherical harmonics representation inside the nonoverlapping atomic spheres. The current is integrated using a “pseudocharge” technique. The implementation is validated by comparison of the computed chemical shifts with some “exact” results for spherical atoms and for a set of solids and molecules with available published data.

  2. 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)

  3. 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.

  4. Chemical-shift MRI of exogenous lipoid pneumonia

    Energy Technology Data Exchange (ETDEWEB)

    Cox, J.E.; Choplin, R.H.; Chiles, C. [Wake Forest Univ., Winston-Salem, NC (United States)

    1996-05-01

    Exogenous lipoid pneumonia results from the aspiration or inhalation of fatty substances, such as mineral oil found in laxatives or nasal medications containing liquid paraffin. We present standard and lipid-sensitive (chemical-shift) MR findings in a patient with histologically confirmed lipoid pneumonia. The loss of signal intensity in an area of airspace disease on opposed-phase imaging was considered specific for the presence of lipid. 14 refs., 3 figs.

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

    Science.gov (United States)

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

    2006-12-01

    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). The differences are due to different conformational behavior of the OH and OCH3 groups; while the ortho-disubstituted OH group remains planar in polyphenols due to hydrogen bonding and conjugative stabilization, the steric congestion in ortho-disubstituted anisoles outweighs the conjugative effects and forces 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 correlation between computed and observed 1H NMR chemical shifts, including agreement between computed and observed chemical shift changes caused by O-methylation. The observed regularities can aid structure elucidation of partly O-methylated polyphenols, including many natural products and drugs, and are useful in connection with chemical shift predictions by desktop computer programs. PMID:17137372

  6. 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...

  7. Database proton NMR chemical shifts for RNA signal assignment and validation

    International Nuclear Information System (INIS)

    The Biological Magnetic Resonance Data Bank contains NMR chemical shift depositions for 132 RNAs and RNA-containing complexes. We have analyzed the 1H NMR chemical shifts reported for non-exchangeable protons of residues that reside within A-form helical regions of these RNAs. The analysis focused on the central base pair within a stretch of three adjacent base pairs (BP triplets), and included both Watson–Crick (WC; G:C, A:U) and G:U wobble pairs. Chemical shift values were included for all 43 possible WC-BP triplets, as well as 137 additional triplets that contain one or more G:U wobbles. Sequence-dependent chemical shift correlations were identified, including correlations involving terminating base pairs within the triplets and canonical and non-canonical structures adjacent to the BP triplets (i.e. bulges, loops, WC and non-WC BPs), despite the fact that the NMR data were obtained under different conditions of pH, buffer, ionic strength, and temperature. A computer program (RNAShifts) was developed that enables convenient comparison of RNA 1H NMR assignments with database predictions, which should facilitate future signal assignment/validation efforts and enable rapid identification of non-canonical RNA structures and RNA-ligand/protein interaction sites.

  8. 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.

  9. Substituent effects on 61Ni NMR chemical shifts

    OpenAIRE

    Bühl, Michael; Peters, Dietmund; Herges, Rainer

    2009-01-01

    Ni-61 chemical shifts of Ni(all-trans-cdt) L (cdt = cyclododecatriene, L = none, CO, PMe3), Ni(CO)(4), Ni(C2H4)(2)(PMe3), Ni(cod)(2) (cod = cyclooctadiene) and Ni(PX3)(4) (X = Me, F, Cl) are computed at the GIAO (gauge-including atomic orbitals), BPW91, B3LYP and BHandHLYP levels, using BP86-optimised geometries and an indirect referencing scheme. For this set of compounds, substituent effects on delta(Ni-61) are better described with hybrid functionals than with the pure BPW91 functional. On...

  10. 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.

  11. Identification of helix capping and {beta}-turn motifs from NMR chemical shifts

    Energy Technology Data Exchange (ETDEWEB)

    Shen Yang; Bax, Ad, E-mail: bax@nih.gov [National Institutes of Health, Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases (United States)

    2012-03-15

    We present an empirical method for identification of distinct structural motifs in proteins on the basis of experimentally determined backbone and {sup 13}C{sup {beta}} chemical shifts. Elements identified include the N-terminal and C-terminal helix capping motifs and five types of {beta}-turns: I, II, I Prime , II Prime and VIII. Using a database of proteins of known structure, the NMR chemical shifts, together with the PDB-extracted amino acid preference of the helix capping and {beta}-turn motifs are used as input data for training an artificial neural network algorithm, which outputs the statistical probability of finding each motif at any given position in the protein. The trained neural networks, contained in the MICS (motif identification from chemical shifts) program, also provide a confidence level for each of their predictions, and values ranging from ca 0.7-0.9 for the Matthews correlation coefficient of its predictions far exceed those attainable by sequence analysis. MICS is anticipated to be useful both in the conventional NMR structure determination process and for enhancing on-going efforts to determine protein structures solely on the basis of chemical shift information, where it can aid in identifying protein database fragments suitable for use in building such structures.

  12. NMR chemical shifts in amino acids: Effects of environments, electric field, and amine group rotation

    International Nuclear Information System (INIS)

    The authors present calculations of NMR chemical shifts in crystalline phases of some representative amino acids such as glycine, alanine, and alanyl-alanine. To get an insight on how different environments affect the chemical shifts, they study the transition from the crystalline phase to completely isolated molecules of glycine. In the crystalline limit, the shifts are dominated by intermolecular hydrogen-bonds. In the molecular limit, however, dipole electric field effects dominate the behavior of the chemical shifts. They show that it is necessary to average the chemical shifts in glycine over geometries. Tensor components are analyzed to get the angle dependent proton chemical shifts, which is a more refined characterization method

  13. 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.

  14. Computational Assignment of Chemical Shifts for Protein Residues

    CERN Document Server

    Bratholm, Lars A

    2013-01-01

    Fast and accurate protein structure prediction is one of the major challenges in structural biology, biotechnology and molecular biomedicine. These fields require 3D protein structures for rational design of proteins with improved or novel properties. X-ray crystallography is the most common approach even with its low success rate, but lately NMR based approaches have gained popularity. The general approach involves a set of distance restraints used to guide a structure prediction, but simple NMR triple-resonance experiments often provide enough structural information to predict the structure of small proteins. Previous protein folding simulations that have utilised experimental data have weighted the experimental data and physical force field terms more or less arbitrarily, and the method is thus not generally applicable to new proteins. Furthermore a complete and near error-free assignment of chemical shifts obtained by the NMR experiments is needed, due to the static, or deterministic, assignment. In this ...

  15. 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

  16. 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

  17. 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

  18. 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...

  19. 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.

  20. Diagnostic value of chemical shift artifact in distinguishing benign lymphadenopathy

    International Nuclear Information System (INIS)

    Purpose: Today, distinguishing metastatic lymph nodes from secondary benign inflammatory ones via using non-invasive methods is increasingly favorable. In this study, the diagnostic value of chemical shift artifact (CSA) in magnetic resonance imaging (MRI) was evaluated to distinguish benign lymphadenopathy. Subjects and methods: A prospective intraindividual internal review board-approved study was carried out on 15 men and 15 women having lymphadenopathic lesions in different locations of the body who underwent contrast-enhanced dynamic MR imaging at 1.5 T. Then, the imaging findings were compared with pathology reports, using the statistics analyses. Results: Due to the findings of the CSA existence in MRI, a total of 56.7% of the studied lesions (17 of 30) were identified as benign lesions and the rest were malignant, whereas the pathology reports distinguished twelve malignant and eighteen benign cases. Furthermore, the CSA findings comparing the pathology reports indicated that CSA, with confidence of 79.5%, has a significant diagnostic value to differentiate benign lesions from malignant ones. Conclusion: Our study demonstrated that CSA in MR imaging has a suitable diagnostic potential nearing readiness for clinical trials. Furthermore, CSA seems to be a feasible tool to differentiate benign lymph nodes from malignant ones; however, further studies including larger numbers of patients are required to confirm our results.

  1. 19-Fluorine nuclear magnetic resonance chemical shift variability in trifluoroacetyl species

    OpenAIRE

    Sloop, Joseph

    2013-01-01

    Joseph C SloopSchool of Science and Technology, Georgia Gwinnett College, Lawrenceville, GA, USAAbstract: This review examines the variability of chemical shifts observed in 19-fluorine (19F) nuclear magnetic resonance spectra for the trifluoroacetyl (TFA) functional group. The range of 19F chemical shifts reported spectra for the TFA group varies generally from −85 to −67 ppm relative to CFCl3. The literature revealed several factors that impact chemical shifts of the TFA...

  2. 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.

  3. Understanding the shift of correlation matrices during financial crisis: A network topology

    Science.gov (United States)

    Yusoff, Nur Syahidah; Sharif, Shamshuritawati

    2015-02-01

    Understanding the shift of correlation matrices in any process is not an easy task. From the literatures, the most popular and widely used test for correlation shift is Jennrich's test. This motivates us to use it in this paper. However, if after hypothesis testing the hypothesis of stable process correlation is rejected, then the next problem is to find out the root causes of that situation. In this paper, network topology approach will be used to understand the shift. A case study will be discussed and presented to illustrate the advantage of this approach.

  4. Equilibrium simulations of proteins using molecular fragment replacement and NMR chemical shifts

    DEFF Research Database (Denmark)

    Boomsma, Wouter; Tian, Pengfei; Frellsen, J.;

    2014-01-01

    Significance Chemical shifts are the most fundamental parameters measured in nuclear magnetic resonance spectroscopy. Since these parameters are exquisitely sensitive to the local atomic environment, they can provide detailed information about the three-dimensional structures of proteins. It has...... their thermal fluctuations, thereby broadening the scope of chemical shifts in structural biology....

  5. Carbon-13 magnetic resonance chemical shift additivity relationships of clinically used furocoumarins and furchromones

    International Nuclear Information System (INIS)

    The natural abundance carbon-13 nuclear magnetic resonance spectra of various clinically used furocoumarins and furochromones have been studied. The assignments of carbon chemical shift values were based on the theory of chemical shift, additivity rules, SFORD spectra and model compounds. (author)

  6. 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.

  7. Low-temperature behavior of transmission phase shift across a Kondo correlated quantum dot

    Science.gov (United States)

    Takada, S.; Yamamoto, M.; Bäuerle, C.; Alex, A.; von Delft, J.; Ludwig, A.; Wieck, A. D.; Tarucha, S.

    2016-08-01

    We study the transmission phase shift across a Kondo correlated quantum dot in a GaAs heterostructure at temperatures below the Kondo temperature (T coefficient through a resonance level near the Fermi energy.

  8. 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.

  9. Method of evaluating chemical shifts of X-ray emission lines in molecules and solids

    OpenAIRE

    Lomachuk, Yuriy V.; Titov, Anatoly V.

    2013-01-01

    Method of evaluating chemical shifts of X-ray emission lines for sufficiently heavy atoms (beginning from period 4 elements) in chemical compounds is developed. This method is based on the pseudopotential model and one-center restoration method (to reconstruct the proper electronic structure in heavy-atom cores). The approximations of instantaneous transition and frozen inner core spinors of the atom are used for derivation of an expression for chemical shift as a difference between mean valu...

  10. 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.

  11. 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. PMID:18648699

  12. Distal and proximal ligand interactions in heme proteins: Correlations between C-O and Fe-C vibrational frequencies, oxygen-17 and carbon-13 nuclear magnetic resonance chemical shifts, and oxygen-17 nuclear quadrupole coupling constants in C sup 17 O- and sup 13 CO-labeled species

    Energy Technology Data Exchange (ETDEWEB)

    Ki Deok Park; Guo, K.; Adebodun, F.; Chiu, M.L.; Sligar, S.G.; Oldfield, E. (Univ. of Illinois, Urbana (United States))

    1991-03-05

    The authors have obtained the oxygen-17 nuclear magnetic resonance (NMR) spectra of a variety of C{sup 17}O-labeled heme proteins, including sperm whale (Physeter catodon) myoglobin, two synthetic sperm whale myoglobin mutants (His E7 {yields} Val E7; His E7 {yields} Phe E7), adult human hemoglobin, rabbit (Oryctolagus cuniculus) hemoglobin, horseradish (Cochlearia armoracia) peroxidase isoenzymes A and C, and Caldariomyces fumago chloroperoxidase, in some cases as a function of pH, and have determined their isotropic {sup 17}O NMR chemical shifts, {delta}{sub i}, and spin-lattice relaxation times, T{sub 1}. They have also obtained similar results on a picket fence prophyrin. The results show an excellent correlation between the infrared C-O vibrational frequencies, {nu}(C-O), and {delta}{sub i}, between {nu}(C-O) and the {sup 17}O nuclear quadrupole coupling constant, and as expected between e{sup 2}qQ/h and {delta}{sub i}. The results suggest the IR and NMR measurements reflect the same interaction, which is thought to be primarily the degree of {pi}-back-bonding from Fe d to CO {pi}* orbitals, as outlined previously.

  13. 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.

  14. Nuclear magnetic resonance shielding constants and chemical shifts in linear 199Hg compounds: a comparison of three relativistic computational methods.

    Science.gov (United States)

    Arcisauskaite, Vaida; Melo, Juan I; Hemmingsen, Lars; Sauer, Stephan P A

    2011-07-28

    We investigate the importance of relativistic effects on NMR shielding constants and chemical shifts of linear HgL(2) (L = Cl, Br, I, CH(3)) compounds using three different relativistic methods: the fully relativistic four-component approach and the two-component approximations, linear response elimination of small component (LR-ESC) and zeroth-order regular approximation (ZORA). LR-ESC reproduces successfully the four-component results for the C shielding constant in Hg(CH(3))(2) within 6 ppm, but fails to reproduce the Hg shielding constants and chemical shifts. The latter is mainly due to an underestimation of the change in spin-orbit contribution. Even though ZORA underestimates the absolute Hg NMR shielding constants by ∼2100 ppm, the differences between Hg chemical shift values obtained using ZORA and the four-component approach without spin-density contribution to the exchange-correlation (XC) kernel are less than 60 ppm for all compounds using three different functionals, BP86, B3LYP, and PBE0. However, larger deviations (up to 366 ppm) occur for Hg chemical shifts in HgBr(2) and HgI(2) when ZORA results are compared with four-component calculations with non-collinear spin-density contribution to the XC kernel. For the ZORA calculations it is necessary to use large basis sets (QZ4P) and the TZ2P basis set may give errors of ∼500 ppm for the Hg chemical shifts, despite deceivingly good agreement with experimental data. A Gaussian nucleus model for the Coulomb potential reduces the Hg shielding constants by ∼100-500 ppm and the Hg chemical shifts by 1-143 ppm compared to the point nucleus model depending on the atomic number Z of the coordinating atom and the level of theory. The effect on the shielding constants of the lighter nuclei (C, Cl, Br, I) is, however, negligible. PMID:21806118

  15. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-11-15

    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 http://www.gamdy.ca.

  17. 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.

  18. 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

  19. 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.

  20. 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)-).

  1. 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.

  2. Supramolecular chemical shift reagents inducing conformational transitions: NMR analysis of carbohydrate homooligomer mixtures

    DEFF Research Database (Denmark)

    Beeren, Sophie; Meier, Sebastian

    2015-01-01

    We introduce the concept of supramolecular chemical shift reagents as a tool to improve signal resolution for the NMR analysis of homooligomers. Non-covalent interactions with the shift reagent can constrain otherwise flexible analytes inducing a conformational transition that results in signal...

  3. AFNMR: automated fragmentation quantum mechanical calculation of NMR chemical shifts for biomolecules

    Energy Technology Data Exchange (ETDEWEB)

    Swails, Jason [Rutgers University, Department of Chemistry and Chemical Biology and BioMaPS Institute (United States); Zhu, Tong; He, Xiao, E-mail: xiaohe@phy.ecnu.edu.cn [East China Normal University, State Key Laboratory of Precision Spectroscopy, Institute of Theoretical and Computational Science (China); Case, David A., E-mail: case@biomaps.rutgers.edu [Rutgers University, Department of Chemistry and Chemical Biology and BioMaPS Institute (United States)

    2015-10-15

    We evaluate the performance of the automated fragmentation quantum mechanics/molecular mechanics approach (AF-QM/MM) on the calculation of protein and nucleic acid NMR chemical shifts. The AF-QM/MM approach models solvent effects implicitly through a set of surface charges computed using the Poisson–Boltzmann equation, and it can also be combined with an explicit solvent model through the placement of water molecules in the first solvation shell around the solute; the latter substantially improves the accuracy of chemical shift prediction of protons involved in hydrogen bonding with solvent. We also compare the performance of AF-QM/MM on proteins and nucleic acids with two leading empirical chemical shift prediction programs SHIFTS and SHIFTX2. Although the empirical programs outperform AF-QM/MM in predicting chemical shifts, the differences are in some cases small, and the latter can be applied to chemical shifts on biomolecules which are outside the training set employed by the empirical programs, such as structures containing ligands, metal centers, and non-standard residues. The AF-QM/MM described here is implemented in version 5 of the SHIFTS software, and is fully automated, so that only a structure in PDB format is required as input.

  4. 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.

  5. 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.)

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

    International Nuclear Information System (INIS)

    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.)

  7. 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)

  8. Method for evaluating chemical shifts of x-ray emission lines in molecules and solids

    Science.gov (United States)

    Lomachuk, Yuriy V.; Titov, Anatoly V.

    2013-12-01

    A method of evaluating chemical shifts of x-ray emission lines for period four and heavier elements is developed. This method is based on the relativistic pseudopotential model and one-center restoration approach [Int. J. Quantum Chem.IJQCB20020-760810.1002/qua.20418 104, 223 (2005)] to recover a proper electronic structure in heavy-atom cores after the pseudopotential simulation of chemical compounds. The approximations of instantaneous transition and frozen core are presently applied to derive an expression for chemical shift as a difference between mean values of certain effective operator. The method allows one to avoid evaluation of small quantities (chemical shifts ˜0.01-1 eV) as differences of very large values (transition energies ˜1-100 keV in various compounds). The results of our calculations of chemical shifts for the Kα1, Kα2, and L transitions of group-14 metal cations with respect to neutral atoms are presented. Calculations of Kα1-line chemical shifts for the Pb core transitions in PbO and PbF2 with respect to those in the Pb atom are also performed and discussed. The accuracy of approximations used is estimated and the quality of the calculations is analyzed.

  9. Method of evaluating chemical shifts of X-ray emission lines in molecules and solids

    CERN Document Server

    Lomachuk, Yuriy V

    2013-01-01

    Method of evaluating chemical shifts of X-ray emission lines for sufficiently heavy atoms (beginning from period 4 elements) in chemical compounds is developed. This method is based on the pseudopotential model and one-center restoration method (to reconstruct the proper electronic structure in heavy-atom cores). The approximations of instantaneous transition and frozen inner core spinors of the atom are used for derivation of an expression for chemical shift as a difference between mean values of some effective operator. The method allows one to avoid evaluating small values (chemical shifts ~ 0.01{\\div}1 eV) as differences of very large values (transition energies ~ 1{\\div}100 keV in various compounds). The results of our calculations of chemical shifts for the K_{\\alpha1,2} and L transitions of the group 14 metal cations with respect to neutral atoms are presented. The calculations of chemical shift of K_{\\alpha1}-line in the Pb-core transition within PbO and PbF_2 with respect to the neutral Pb are also p...

  10. 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.

  11. Theoretical Modeling of (99)Tc NMR Chemical Shifts.

    Science.gov (United States)

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

    2016-09-01

    Technetium-99 (Tc) displays a rich chemistry due to its wide range of accessible oxidation states (from -I to +VII) and ability to form coordination compounds. Determination of Tc speciation in complex mixtures is a major challenge, and (99)Tc nuclear magnetic resonance (NMR) spectroscopy is widely used to probe chemical environments of Tc in odd oxidation states. However, interpretation of (99)Tc NMR data is hindered by the lack of reference compounds. Density functional theory (DFT) calculations can help to fill this gap, but to date few computational studies have focused on (99)Tc NMR of compounds and complexes. This work evaluates the effectiveness of both pure generalized gradient approximation and their corresponding hybrid functionals, both with and without the inclusion of scalar relativistic effects, to model the (99)Tc NMR spectra of Tc(I) carbonyl compounds. With the exception of BLYP, which performed exceptionally well overall, hybrid functionals with inclusion of scalar relativistic effects are found to be necessary to accurately calculate (99)Tc NMR spectra. The computational method developed was used to tentatively assign an experimentally observed (99)Tc NMR peak at -1204 ppm to fac-Tc(CO)3(OH)3(2-). This study examines the effectiveness of DFT computations for interpretation of the (99)Tc NMR spectra of Tc(I) coordination compounds in high salt alkaline solutions. PMID:27518482

  12. RefDB: A database of uniformly referenced protein chemical shifts

    International Nuclear Information System (INIS)

    RefDB is a secondary database of reference-corrected protein chemical shifts derived from the BioMagResBank (BMRB). The database was assembled by using a recently developed program (SHIFTX) to predict protein 1H, 13C and 15N chemical shifts from X-ray or NMR coordinate data of previously assigned proteins. The predicted shifts were then compared with the corresponding observed shifts and a variety of statistical evaluations performed. In this way, potential mis-assignments, typographical errors and chemical referencing errors could be identified and, in many cases, corrected. This approach allows for an unbiased, instrument-independent solution to the problem of retrospectively re-referencing published protein chemical shifts. Results from this study indicate that nearly 25% of BMRB entries with 13C protein assignments and 27% of BMRB entries with 15N protein assignments required significant chemical shift reference readjustments. Additionally, nearly 40% of protein entries deposited in the BioMagResBank appear to have at least one assignment error. From this study it evident that protein NMR spectroscopists are increasingly adhering to recommended IUPAC 13C and 15N chemical shift referencing conventions, however, approximately 20% of newly deposited protein entries in the BMRB are still being incorrectly referenced. This is cause for some concern. However, the utilization of RefDB and its companion programs may help mitigate this ongoing problem. RefDB is updated weekly and the database, along with its associated software, is freely available at http://redpoll.pharmacy.ualberta.ca and the BMRB website

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

    Energy Technology Data Exchange (ETDEWEB)

    Labudde, D.; Leitner, D.; Krueger, M.; Oschkinat, H. [Forschungsinstitut fuer Molekulare Pharmakologie (Germany)], E-mail: oschkinat@fmp-berlin.de

    2003-01-15

    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.

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

    Directory of Open Access Journals (Sweden)

    Anders S Christensen

    Full Text Available 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 ((h3J(NC' 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 obtain this agreement. The ProCS method thus offers a powerful new tool for refining the structures of hydrogen bonding networks to high accuracy with many potential applications such as protein flexibility in ligand binding.

  15. 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...

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

    International Nuclear Information System (INIS)

    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 α-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 α-helix, β-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. 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......” and tautomeric systems. Isotope effects on chemical shifts are particularly useful in such studies. All kinds of intramolecular hydrogen bonded systems will be treated, typical hydrogen bond donors: OH, NH, SH and NH+, typical acceptors C=O, C=N, C=S C=N−. The paper will be deal with both secondary...... and primary isotope effects on chemical shifts. These two types of isotope effects monitor the same hydrogen bond, but from different angles...

  18. 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......” and tautomeric systems. Isotope effects on chemical shifts are particularly useful in such studies. All kinds of intramolecular hydrogen bonded systems will be treated, typical hydrogen bond donors: OH, NH, SH and NH+, typical acceptors C=O, C=N, C=S C=N−. The paper will be deal with both secondary and primary...... isotope effects on chemical shifts. These two types of isotope effects monitor the same hydrogen bond, but from different angles...

  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

    ” 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...... indicating transmission via the hydrogen bond. In addition, unusual long range effects are seen. Structures, 1H and 13C NMR chemical shifts and changes in nuclear shieldings upon deuteriation are calculated using density functional theory methods......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...

  20. Quantification of fat using chemical shift imaging and 1H-MR spectroscopy in phantom model

    International Nuclear Information System (INIS)

    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 poly, unsaturation 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 (paired- samples t test, t=-0.125, P=0.903). By using MRS, the relative ratio of FS and FU in fat were 0. 15 and 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. (authors)

  1. Pulse NMR in solids: chemical shift, lead fluoride, and thorium hydride

    International Nuclear Information System (INIS)

    The fluorine chemical shift of a single crystal CaF2 was measured up to 4 kilobar at room temperature using multiple pulse NMR. The pressure dependence of the shift is found to be --1.7 +- 1 ppM/kbar, while an overlap model predicts a shift of --0.46 ppM/kbar.The chemical shift tensor is separated into ''geometrical'' and ''chemical'' contributions, and comparison of the proposed model calculations with recent data on hydroxyl proton chemical shift tensors shows that the geometrical portion accounts for the qualitative features of the measured tensors. A study of fluoride ion motion in β-PbF2 doped with NaF was conducted by measurement of the 19F transverse relaxation time (T2), spin lattice relaxation time (T1) and the spin lattice relaxation time in the rotating frame (T/sub 1r). Two samples of Th4H15, prepared under different conditions but both having the proper ratio of H/Th (to within 1 percent), were studied. The structure of the Th4H15 suggested by x-ray measurements is confirmed through a moment analysis of the rigid lattice line shape

  2. 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 me......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...

  3. 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.

  4. 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.

  5. 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.

  6. Proton Magnetic Resonance and Human Thyroid Neoplasia III. Ex VivoChemical-Shift Microimaging

    Science.gov (United States)

    Rutter, Allison; Künnecke, Basil; Dowd, Susan; Russell, Peter; Delbridge, Leigh; Mountford, Carolyn E.

    1996-03-01

    Magnetic-resonance chemical-shift microimaging, with a spatial resolution of 40 × 40 μm, is a modality which can detect alterations to cellular chemistry and hence markers of pathological processes in human tissueex vivo.This technique was used as a chemical microscope to assess follicular thyroid neoplasms, lesions which are unsatisfactorily investigated using standard histopathological techiques or water-based magnetic-resonance imaging. The chemical-shift images at the methyl frequency (0.9 ppm) identify chemical heterogeneity in follicular tumors which are histologically homogeneous. The observed changes to cellular chemistry, detectable in foci of approximately 100 cells or less, support the existence of a preinvasive state hitherto unidentified by current pathological techniques.

  7. 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. PMID:27335085

  8. 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.

  9. 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

  10. Automated assignment of NMR chemical shifts based on a known structure and 4D spectra.

    Science.gov (United States)

    Trautwein, Matthias; Fredriksson, Kai; Möller, Heiko M; Exner, Thomas E

    2016-08-01

    Apart from their central role during 3D structure determination of proteins the backbone chemical shift assignment is the basis for a number of applications, like chemical shift perturbation mapping and studies on the dynamics of proteins. This assignment is not a trivial task even if a 3D protein structure is known and needs almost as much effort as the assignment for structure prediction if performed manually. We present here a new algorithm based solely on 4D [(1)H,(15)N]-HSQC-NOESY-[(1)H,(15)N]-HSQC spectra which is able to assign a large percentage of chemical shifts (73-82 %) unambiguously, demonstrated with proteins up to a size of 250 residues. For the remaining residues, a small number of possible assignments is filtered out. This is done by comparing distances in the 3D structure to restraints obtained from the peak volumes in the 4D spectrum. Using dead-end elimination, assignments are removed in which at least one of the restraints is violated. Including additional information from chemical shift predictions, a complete unambiguous assignment was obtained for Ubiquitin and 95 % of the residues were correctly assigned in the 251 residue-long N-terminal domain of enzyme I. The program including source code is available at https://github.com/thomasexner/4Dassign . PMID:27484442

  11. 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

    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 an...

  12. 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…

  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. 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

  15. 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

  16. 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). PMID:26787258

  17. 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).

  18. 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.

  19. 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.

  20. Noninvasive Temperature Mapping With MRI Using Chemical Shift Water-Fat Separation

    OpenAIRE

    Soher, Brian J.; Wyatt, Cory; Reeder, Scott B.; MacFall, James R.

    2010-01-01

    Tissues containing both water and lipids, e.g., breast, confound standard MR proton reference frequency-shift methods for mapping temperatures due to the lack of temperature-induced frequency shift in lipid protons. Generalized Dixon chemical shift–based water-fat separation methods, such as GE’s iterative decomposition of water and fat with echo asymmetry and least-squares estimation method, can result in complex water and fat images. Once separated, the phase change over time of the water s...

  1. Application of multivariate image analysis in QSPR study of 13C chemical shifts of naphthalene derivatives: a comparative study.

    Science.gov (United States)

    Garkani-Nejad, Zahra; Poshteh-Shirani, Marziyeh

    2010-11-15

    A new implemented QSPR method, whose descriptors achieved from bidimensional images, was applied for predicting (13)C NMR chemical shifts of 25 mono substituted naphthalenes. The resulted descriptors were subjected to principal component analysis (PCA) and the most significant principal components (PCs) were extracted. MIA-QSPR (multivariate image analysis applied to quantitative structure-property relationship) modeling was done by means of principal component regression (PCR) and principal component-artificial neural network (PC-ANN) methods. Eigen value ranking (EV) and correlation ranking (CR) were used here to select the most relevant set of PCs as inputs for PCR and PC-ANN modeling methods. The results supported that the correlation ranking-principal component-artificial neural network (CR-PC-ANN) model could predict the (13)C NMR chemical shifts of all 10 carbon atoms in mono substituted naphthalenes with R(2) ≥ 0.922 for training set, R(2) ≥ 0.963 for validation set and R(2) ≥ 0.936 for the test set. Comparison of the results with other existing factor selection method revealed that less accurate results were obtained by the eigen value ranking procedure. PMID:21035668

  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. PMID:24752730

  3. 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.

  4. 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.

  5. Protein backbone and sidechain torsion angles predicted from NMR chemical shifts using artificial neural networks

    Energy Technology Data Exchange (ETDEWEB)

    Shen Yang; Bax, Ad, E-mail: bax@nih.gov [National Institutes of Health, Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases (United States)

    2013-07-15

    A new program, TALOS-N, is introduced for predicting protein backbone torsion angles from NMR chemical shifts. The program relies far more extensively on the use of trained artificial neural networks than its predecessor, TALOS+. Validation on an independent set of proteins indicates that backbone torsion angles can be predicted for a larger, {>=}90 % fraction of the residues, with an error rate smaller than ca 3.5 %, using an acceptance criterion that is nearly two-fold tighter than that used previously, and a root mean square difference between predicted and crystallographically observed ({phi}, {psi}) torsion angles of ca 12 Masculine-Ordinal-Indicator . TALOS-N also reports sidechain {chi}{sup 1} rotameric states for about 50 % of the residues, and a consistency with reference structures of 89 %. The program includes a neural network trained to identify secondary structure from residue sequence and chemical shifts.

  6. Correlating Wine Quality Indicators to Chemical and Sensory Measurements

    Directory of Open Access Journals (Sweden)

    Helene Hopfer

    2015-05-01

    Full Text Available Twenty-seven commercial Californian Cabernet Sauvignon wines of different quality categories were analyzed with sensory and chemical methods. Correlations between five quality proxies—points awarded during a wine competition, wine expert scores, retail price, vintage, and wine region—were correlated to sensory attributes, volatile compounds, and elemental composition. Wine quality is a multi-faceted construct, incorporating many different layers. Depending on the quality proxy studied, significant correlations between quality and attributes, volatiles and elements were found, some of them previously reported in the literature.

  7. 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.

  8. Using Neural Networks for 13C NMR Chemical Shift Prediction-Comparison with Traditional Methods

    Science.gov (United States)

    Meiler, Jens; Maier, Walter; Will, Martin; Meusinger, Reinhard

    2002-08-01

    Interpretation of 13C chemical shifts is essential for structure elucidation of organic molecules by NMR. In this article, we present an improved neural network approach and compare its performance to that of commonly used approaches. Specifically, our recently proposed neural network ( J. Chem. Inf. Comput. Sci. 2000, 40, 1169-1176) is improved by introducing an extended hybrid numerical description of the carbon atom environment, resulting in a standard deviation (std. dev.) of 2.4 ppm for an independent test data set of ˜42,500 carbons. Thus, this neural network allows fast and accurate 13C NMR chemical shift prediction without the necessity of access to molecule or fragment databases. For an unbiased test dataset containing 100 organic structures the accuracy of the improved neural network was compared to that of a prediction method based on the HOSE code ( hierarchically ordered spherical description of environment) using S PECI NFO. The results show the neural network predictions to be of quality (std. dev.=2.7 ppm) comparable to that of the HOSE code prediction (std. dev.=2.6 ppm). Further we compare the neural network predictions to those of a wide variety of other 13C chemical shift prediction tools including incremental methods (C HEMD RAW, S PECT OOL), quantum chemical calculation (G AUSSIAN, C OSMOS), and HOSE code fragment-based prediction (S PECI NFO, ACD/CNMR, P REDICTI T NMR) for the 47 13C-NMR shifts of Taxol, a natural product including many structural features of organic substances. The smallest standard deviations were achieved here with the neural network (1.3 ppm) and S PECI NFO (1.0 ppm).

  9. Fragment-Based Electronic Structure Approach for Computing Nuclear Magnetic Resonance Chemical Shifts in Molecular Crystals.

    Science.gov (United States)

    Hartman, Joshua D; Beran, Gregory J O

    2014-11-11

    First-principles chemical shielding tensor predictions play a critical role in studying molecular crystal structures using nuclear magnetic resonance. Fragment-based electronic structure methods have dramatically improved the ability to model molecular crystal structures and energetics using high-level electronic structure methods. Here, a many-body expansion fragment approach is applied to the calculation of chemical shielding tensors in molecular crystals. First, the impact of truncating the many-body expansion at different orders and the role of electrostatic embedding are examined on a series of molecular clusters extracted from molecular crystals. Second, the ability of these techniques to assign three polymorphic forms of the drug sulfanilamide to the corresponding experimental (13)C spectra is assessed. This challenging example requires discriminating among spectra whose (13)C chemical shifts differ by only a few parts per million (ppm) across the different polymorphs. Fragment-based PBE0/6-311+G(2d,p) level chemical shielding predictions correctly assign these three polymorphs and reproduce the sulfanilamide experimental (13)C chemical shifts with 1 ppm accuracy. The results demonstrate that fragment approaches are competitive with the widely used gauge-invariant projector augmented wave (GIPAW) periodic density functional theory calculations. PMID:26584373

  10. 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.

  11. 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.

  12. 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

    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.

  13. 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.

  14. 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.

  15. 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).

  16. Correlation between biogas yield and chemical composition of energy crops.

    Science.gov (United States)

    Dandikas, V; Heuwinkel, H; Lichti, F; Drewes, J E; Koch, K

    2014-12-01

    The scope of this study was to investigate the influence of the chemical composition of energy crops on biogas and methane yield. In total, 41 different plants were analyzed in batch test and their chemical composition was determined. For acid detergent lignin (ADL) content below 10% of total solids, a significant negative correlation for biogas and methane yields (r≈-0.90) was observed. Based on a simple regression analysis, more than 80% of the sample variation can be explained through ADL. Based on a principal component analysis and multiple regression analysis, ADL and hemicellulose are suggested as suitable model variables for biogas yield potential predictions across plant species. PMID:25443623

  17. NMR chemical shift pattern changed by ammonium sulfate precipitation in cyanobacterial phytochrome Cph1

    Directory of Open Access Journals (Sweden)

    Chen eSong

    2015-07-01

    Full Text Available Phytochromes are dimeric biliprotein photoreceptors exhibiting characteristic red/far-red photocycles. Full-length cyanobacterial phytochrome Cph1 from Synechocystis 6803 is soluble initially but tends to aggregate in a concentration-dependent manner, hampering attempts to solve the structure using NMR and crystallization methods. Otherwise, the Cph1 sensory module (Cph1Δ2, photochemically indistinguishable from the native protein and used extensively in structural and other studies, can be purified to homogeneity in >10 mg amounts at mM concentrations quite easily. Bulk precipitation of full-length Cph1 by ammonium sulfate (AmS was expected to allow us to produce samples for solid-state magic-angle spinning (MAS NMR from dilute solutions before significant aggregation began. It was not clear, however, what effects the process of partial dehydration might have on the molecular structure. Here we test this by running solid-state MAS NMR experiments on AmS-precipitated Cph1Δ2 in its red-absorbing Pr state carrying uniformly 13C/15N-labeled phycocyanobilin (PCB chromophore. 2D 13C–13C correlation experiments allowed a complete assignment of 13C responses of the chromophore. Upon precipitation, 13C chemical shifts for most of PCB carbons move upfield, in which we found major changes for C4 and C6 atoms associated with the A-ring positioning. Further, the broad spectral lines seen in the AmS 13C spectrum reflect primarily the extensive homogeneous broadening presumably due to an increase in the distribution of conformational states in the protein, in which less free water is available to partake in the hydration shells. Our data suggest that dehydration indeed leads to motional and electronic structural changes of the bilin chromophore and its binding pocket and is not restricted to the protein surface. The extent of the changes induced differs from the freezing process of the solution samples routinely used in previous MAS NMR and

  18. NMR chemical shift pattern changed by ammonium sulfate precipitation in cyanobacterial phytochrome Cph1.

    Science.gov (United States)

    Song, Chen; Lang, Christina; Kopycki, Jakub; Hughes, Jon; Matysik, Jörg

    2015-01-01

    Phytochromes are dimeric biliprotein photoreceptors exhibiting characteristic red/far-red photocycles. Full-length cyanobacterial phytochrome Cph1 from Synechocystis 6803 is soluble initially but tends to aggregate in a concentration-dependent manner, hampering attempts to solve the structure using NMR and crystallization methods. Otherwise, the Cph1 sensory module (Cph1Δ2), photochemically indistinguishable from the native protein and used extensively in structural and other studies, can be purified to homogeneity in >10 mg amounts at mM concentrations quite easily. Bulk precipitation of full-length Cph1 by ammonium sulfate (AmS) was expected to allow us to produce samples for solid-state magic-angle spinning (MAS) NMR from dilute solutions before significant aggregation began. It was not clear, however, what effects the process of partial dehydration might have on the molecular structure. Here we test this by running solid-state MAS NMR experiments on AmS-precipitated Cph1Δ2 in its red-absorbing Pr state carrying uniformly (13)C/(15)N-labeled phycocyanobilin (PCB) chromophore. 2D (13)C-(13)C correlation experiments allowed a complete assignment of (13)C responses of the chromophore. Upon precipitation, (13)C chemical shifts for most of PCB carbons move upfield, in which we found major changes for C4 and C6 atoms associated with the A-ring positioning. Further, the broad spectral lines seen in the AmS (13)C spectrum reflect primarily the extensive inhomogeneous broadening presumably due to an increase in the distribution of conformational states in the protein, in which less free water is available to partake in the hydration shells. Our data suggest that the effect of dehydration process indeed leads to changes of electronic structure of the bilin chromophore and a decrease in its mobility within the binding pocket, but not restricted to the protein surface. The extent of the changes induced differs from the freezing process of the solution samples routinely

  19. NMR chemical shift analysis of the conformational transition between the monomer and tetramer of melittin in an aqueous solution.

    Science.gov (United States)

    Miura, Yoshinori

    2016-05-01

    It is known that melittin in an aqueous solution undergoes a conformational transition between the monomer and tetramer by variation in temperature. The transition correlates closely with isomers of the proline residue; monomeric melittin including a trans proline peptide bond (trans-monomer) is involved directly in the transition, whereas monomeric melittin having a cis proline peptide bond (cis-monomer) is virtually not. The transition has been explored by using nuclear magnetic resonance spectroscopy in order to clarify the stability of the tetrameric conformation and the cooperativity of the transition. In the light of temperature dependence of chemical shifts of resonances from the isomeric monomers, we qualitatively estimate the temperature-, salt-, and concentration-dependence of the relative equilibrium populations of the trans-monomer and tetramer, and show that the tetramer has a maximum conformational stability at 30-45 °C and that the transition cooperativity is very low. PMID:26658745

  20. SPARTA+: a modest improvement in empirical NMR chemical shift prediction by means of an artificial neural network

    Energy Technology Data Exchange (ETDEWEB)

    Shen Yang; Bax, Ad, E-mail: bax@nih.go [National Institutes of Health, Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases (United States)

    2010-09-15

    NMR chemical shifts provide important local structural information for proteins and are key in recently described protein structure generation protocols. We describe a new chemical shift prediction program, SPARTA+, which is based on artificial neural networking. The neural network is trained on a large carefully pruned database, containing 580 proteins for which high-resolution X-ray structures and nearly complete backbone and {sup 13}C{sup {beta}} chemical shifts are available. The neural network is trained to establish quantitative relations between chemical shifts and protein structures, including backbone and side-chain conformation, H-bonding, electric fields and ring-current effects. The trained neural network yields rapid chemical shift prediction for backbone and {sup 13}C{sup {beta}} atoms, with standard deviations of 2.45, 1.09, 0.94, 1.14, 0.25 and 0.49 ppm for {delta}{sup 15}N, {delta}{sup 13}C', {delta}{sup 13}C{sup {alpha}}, {delta}{sup 13}C{sup {beta}}, {delta}{sup 1}H{sup {alpha}} and {delta}{sup 1}H{sup N}, respectively, between the SPARTA+ predicted and experimental shifts for a set of eleven validation proteins. These results represent a modest but consistent improvement (2-10%) over the best programs available to date, and appear to be approaching the limit at which empirical approaches can predict chemical shifts.

  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. 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...

  3. Model analysis of influences of the high-temperature reactor on location shifting in chemical industry

    International Nuclear Information System (INIS)

    An analysis is presented of the influences of High-Temperature Reactor on probable location shifting of big chemical plants, in the future. This is done by a spatial location model, that includes an investigation on 116 industrial locations within the first six countries of Common Market. The results of a computerized program show differences in location qualities when furnished either with traditional or with nuclear energy systems. In addition to location factor energy some other important factors, as subventions, taxes, labour, and transport costs are analysed, and their influence on industrial location is quantified. (orig.)

  4. Calculation of NMR chemical shifts. 7. Gauge-invariant INDO method

    Science.gov (United States)

    Fukui, H.; Miura, K.; Hirai, A.

    A gauge-invariant INDO method based on the coupled Hartree-Fuck perturbation theory is presented and applied to the calculation of 1H and 13C chemical shifts of hydrocarbons including ring compounds. Invariance of the diamagnetic and paramagnetic shieldings with respect to displacement of the coordinate origin is discussed. Comparison between calculated and experimental results exhibits fairly good agreement, provided that the INDO parameters of Ellis et al. (J. Am. Chem. Soc.94, 4069 (1972)) are used with the inclusion of all multicenter one-electron integrals.

  5. 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.

  6. 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

  7. 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.

  8. Probing the solvent shell with 195Pt chemical shifts: density functional theory molecular dynamics study of Pt(II) and Pt(IV) anionic complexes in aqueous solution.

    Science.gov (United States)

    Truflandier, Lionel A; Autschbach, Jochen

    2010-03-17

    Ab initio molecular dynamics (aiMD) simulations based on density functional theory (DFT) were performed on a set of five anionic platinum complexes in aqueous solution. (195)Pt nuclear magnetic shielding constants were computed with DFT as averages over the aiMD trajectories, using the two-component relativistic zeroth-order regular approximation (ZORA) in order to treat relativistic effects on the Pt shielding tensors. The chemical shifts obtained from the aiMD averages are in good agreement with experimental data. For Pt(II) and Pt(IV) halide complexes we found an intermediate solvent shell interacting with the complexes that causes pronounced solvent effects on the Pt chemical shifts. For these complexes, the magnitude of solvent effects on the Pt shielding constant can be correlated with the surface charge density. For square-planar Pt complexes the aiMD simulations also clearly demonstrate the influence of closely coordinated non-equatorial water molecules on the Pt chemical shift, relating the structure of the solution around the complex to the solvent effects on the metal NMR chemical shift. For the complex [Pt(CN)(4)](2-), the solvent effects on the Pt shielding constant are surprisingly small. PMID:20166712

  9. Qualitative Study of Substituent Effects on NMR 15N and 17O Chemical Shifts

    Science.gov (United States)

    Contreras, Rubén H.; Llorente, Tomás; Pagola, Gabriel I.; Bustamante, Manuel G.; Pasqualini, Enrique E.; Melo, Juan I.; Tormena, Cláudio F.

    2009-08-01

    A qualitative approach to analyze the electronic origin of substituent effects on the paramagnetic part of chemical shifts is described and applied to few model systems, where its potentiality can be appreciated. The formulation of this approach is based on the following grounds. The influence of different inter- or intramolecular interactions on a second-order property can be qualitatively predicted if it can be known how they affect the main virtual excitations entering into that second-order property. A set of consistent approximations are introduced in order to analyze the behavior of occupied and virtual orbitals that define some experimental trends of magnetic shielding constants. This approach is applied first to study the electronic origin of methyl-β substituent effects on both 15N and 17O chemical shifts, and afterward it is applied to a couple of examples of long-range substituent effects originated in charge transfer interactions such as the conjugative effect in aromatic compounds and σ-hyperconjugative interactions in saturated multicyclic compounds.

  10. Qualitative study of substituent effects on NMR (15)N and (17)O chemical shifts.

    Science.gov (United States)

    Contreras, Rubén H; Llorente, Tomás; Pagola, Gabriel I; Bustamante, Manuel G; Pasqualini, Enrique E; Melo, Juan I; Tormena, Cláudio F

    2009-09-10

    A qualitative approach to analyze the electronic origin of substituent effects on the paramagnetic part of chemical shifts is described and applied to few model systems, where its potentiality can be appreciated. The formulation of this approach is based on the following grounds. The influence of different inter- or intramolecular interactions on a second-order property can be qualitatively predicted if it can be known how they affect the main virtual excitations entering into that second-order property. A set of consistent approximations are introduced in order to analyze the behavior of occupied and virtual orbitals that define some experimental trends of magnetic shielding constants. This approach is applied first to study the electronic origin of methyl-beta substituent effects on both (15)N and (17)O chemical shifts, and afterward it is applied to a couple of examples of long-range substituent effects originated in charge transfer interactions such as the conjugative effect in aromatic compounds and sigma-hyperconjugative interactions in saturated multicyclic compounds. PMID:19685922

  11. 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.

  12. Functional shifts in unvegetated, perhumid, recently-deglaciated soils do not correlate with shifts in soil bacterial community composition.

    Science.gov (United States)

    Sattin, Sarah R; Cleveland, Cory C; Hood, Eran; Reed, Sasha C; King, Andrew J; Schmidt, Steven K; Robeson, Michael S; Ascarrunz, Nataly; Nemergut, Diana R

    2009-12-01

    Past work in recently deglaciated soils demonstrates that microbial communities undergo shifts prior to plant colonization. To date, most studies have focused on relatively 'long' chronosequences with the ability to sample plant-free sites over at least 50 years of development. However, some recently deglaciated soils feature rapid plant colonization and questions remain about the relative rate of change in the microbial community in the unvegetated soils of these chronosequences. Thus, we investigated the forelands of the Mendenhall Glacier near Juneau, AK, USA, where plants rapidly establish. We collected unvegetated samples representing soils that had been ice-free for 0, 1, 4, and 8 years. Total nitrogen (N) ranged from 0.00 approximately 0.14 mg/g soil, soil organic carbon pools ranged from 0.6 approximately 2.3 mg/g soil, and both decreased in concentration between the 0 and 4 yr soils. Biologically available phosphorus (P) and pH underwent similar dynamics. However, both pH and available P increased in the 8 yr soils. Nitrogen fixation was nearly undetectable in the most recently exposed soils, and increased in the 8 yr soils to approximately 5 ng N fixed/cm(2)/h, a trend that was matched by the activity of the soil N-cycling enzymes urease and beta-l,4-N-acetyl-glucosa-minidase. 16S rRNA gene clone libraries revealed no significant differences between the 0 and 8 yr soils; however, 8 yr soils featured the presence of cyanobacteria, a division wholly absent from the 0 yr soils. Taken together, our results suggest that microbes are consuming allochtonous organic matter sources in the most recently exposed soils. Once this carbon source is depleted, a competitive advantage may be ceded to microbes not reliant on in situ nutrient sources. PMID:20127458

  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

    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. 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.

  15. 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

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

    International Nuclear Information System (INIS)

    Highlights: • We present a large cohort of patients who underwent dual and triple echo chemical shift imaging against multi-echo T2 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 T2* 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 T2 corrected MR spectroscopy (MRS) used as the reference standard, and examine the effect of T2* 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 T2* 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 T2*, 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 liver fat in the clinical environment, even in the presence of

  17. Water-fat imaging and general chemical shift imaging with spectrum modeling

    Science.gov (United States)

    An, Li

    Water-fat chemical shift imaging (CSI) has been an active research area in magnetic resonance imaging (MRI) since the early 1980's. There are two main reasons for water- fat imaging. First, water-fat imaging can serve as a fat- suppression method. Removing the usually bright fatty signals not only extends the useful dynamic range of an image, but also allows better visualization of lesions or injected contrast, and removes chemical shift artifacts, which may contribute to improved diagnosis. Second, quantification of water and fat provides useful chemical information for characterizing tissues such as bone marrow, liver, and adrenal masses. A milestone in water- fat imaging is the Dixon method that can produce separate water and fat images with only two data acquisitions. In practice, however, the Dixon method is not always successful due to field inhomogeneity problems. In recent years, many variations of the Dixon method have been proposed to overcome the field inhomogeneity problem. In general, these methods can at best separate water and fat without identifying the two because the water and fat magnetization vectors are sampled symmetrically, only parallel and anti-parallel. Furthermore, these methods usually depend on two-dimensional phase unwrapping which itself is sensitive to noise and artifacts, and becomes unreliable when the images have disconnected tissues in the field-of-view (FOV). We will first introduce the basic principles of nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) in chapter 1, and briefly review the existing water-fat imaging techniques in chapter 2. In chapter 3, we will introduce a new method for water-fat imaging. With three image acquisitions, a general direct phase encoding (DPE) of the chemical shift information is achieved, which allows an unambiguous determination of water and fat on a pixel by pixel basis. Details of specific implementations and noise performance will be discussed. Representative results

  18. Chemical potential shift in organic field-effect transistors identified by soft X-ray operando nano-spectroscopy

    Science.gov (United States)

    Nagamura, Naoka; Kitada, Yuta; Tsurumi, Junto; Matsui, Hiroyuki; Horiba, Koji; Honma, Itaru; Takeya, Jun; Oshima, Masaharu

    2015-06-01

    A chemical potential shift in an organic field effect transistor (OFET) during operation has been revealed by soft X-ray operando nano-spectroscopy analysis performed using a three-dimensional nanoscale electron-spectroscopy chemical analysis system. OFETs were fabricated using ultrathin (3 ML or 12 nm) single-crystalline C10-DNBDT-NW films on SiO2 (200 nm)/Si substrates with a backgate electrode and top source/drain Au electrodes, and C 1s line profiles under biasing at the backgate and drain electrodes were measured. When applying -30 V to the backgate, there is C 1s core level shift of 0.1 eV; this shift can be attributed to a chemical potential shift corresponding to band bending by the field effect, resulting in p-type doping.

  19. Chemical potential shift in organic field-effect transistors identified by soft X-ray operando nano-spectroscopy

    International Nuclear Information System (INIS)

    A chemical potential shift in an organic field effect transistor (OFET) during operation has been revealed by soft X-ray operando nano-spectroscopy analysis performed using a three-dimensional nanoscale electron-spectroscopy chemical analysis system. OFETs were fabricated using ultrathin (3 ML or 12 nm) single-crystalline C10-DNBDT-NW films on SiO2 (200 nm)/Si substrates with a backgate electrode and top source/drain Au electrodes, and C 1s line profiles under biasing at the backgate and drain electrodes were measured. When applying −30 V to the backgate, there is C 1s core level shift of 0.1 eV; this shift can be attributed to a chemical potential shift corresponding to band bending by the field effect, resulting in p-type doping

  20. Chemical potential shift in organic field-effect transistors identified by soft X-ray operando nano-spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Nagamura, Naoka, E-mail: NAGAMURA.Naoka@nims.go.jp; Kitada, Yuta; Honma, Itaru [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Tsurumi, Junto; Matsui, Hiroyuki; Takeya, Jun [Department of Advanced Materials Science, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561 (Japan); Horiba, Koji [Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Oshima, Masaharu [Synchrotron Radiation Research Organization, The University of Tokyo, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan)

    2015-06-22

    A chemical potential shift in an organic field effect transistor (OFET) during operation has been revealed by soft X-ray operando nano-spectroscopy analysis performed using a three-dimensional nanoscale electron-spectroscopy chemical analysis system. OFETs were fabricated using ultrathin (3 ML or 12 nm) single-crystalline C10-DNBDT-NW films on SiO{sub 2} (200 nm)/Si substrates with a backgate electrode and top source/drain Au electrodes, and C 1s line profiles under biasing at the backgate and drain electrodes were measured. When applying −30 V to the backgate, there is C 1s core level shift of 0.1 eV; this shift can be attributed to a chemical potential shift corresponding to band bending by the field effect, resulting in p-type doping.

  1. 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…

  2. 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.

  3. Improving the chemical shift dispersion of multidimensional NMR spectra of intrinsically disordered proteins

    Energy Technology Data Exchange (ETDEWEB)

    Bermel, Wolfgang [Bruker BioSpin GmbH (Germany); Bruix, Marta [Consejo Superior de Investigaciones Cientificas, Instituto de Quimica Fisica ' ' Rocasolano' ' (Spain); Felli, Isabella C., E-mail: felli@cerm.unifi.it [University of Florence, Department of Chemistry ' Ugo Shiff' (Italy); Kumar, M.V. Vasantha [University of Florence, Magnetic Resonance Center (Italy); Pierattelli, Roberta, E-mail: pierattelli@cerm.unifi.it [University of Florence, Department of Chemistry ' Ugo Shiff' (Italy); Serrano, Soraya [Consejo Superior de Investigaciones Cientificas, Instituto de Quimica Fisica ' ' Rocasolano' ' (Spain)

    2013-03-15

    Intrinsically disordered proteins (IDPs) have recently attracted the attention of the scientific community challenging the well accepted structure-function paradigm. In the characterization of the dynamic features of proteins nuclear magnetic resonance spectroscopy (NMR) is a strategic tool of investigation. However the peculiar properties of IDPs, with the lack of a unique 3D structure and their high flexibility, have a strong impact on NMR observables (low chemical shift dispersion, efficient solvent exchange broadening) and thus on the quality of NMR spectra. Key aspects to be considered in the design of new NMR experiments optimized for the study of IDPs are discussed. A new experiment, based on direct detection of {sup 13}C{sup {alpha}}, is proposed.

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

    International Nuclear Information System (INIS)

    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 ultraviolet 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±0.02 for 4-Methylumbelliferone, stable within 0.5% over 50 days, 1.37±0.03 for Carbostyril-124, and 1.20±0.02 for Amino-G Salt. The response of 4-Methylumbelliferone was modeled, resulting in a simulated gain within 9% of the experimental gain at 1 ppm concentration. Finally, we report an increase in neutron detection performance of a large-scale (3.5 kL) gadolinium-doped water Cherenkov detector at a 4-Methylumbelliferone concentration of 1 ppm.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-09-21

    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 {+-} 0.02 for 4-Methylumbelliferone, stable to within 0.5% over 50 days, 1.37 {+-} 0.03 for Carbostyril-124, and 1.20 {+-} 0.02 for Amino-G Salt. The response of 4-Methylumbelliferone was modeled, resulting in a simulated gain within 9% of the experimental gain at 1 ppm concentration. Finally, we report an increase in neutron detection performance of a large-scale (3.5 kL) gadolinium-doped water Cherenkov detector at a 4-Methylumbelliferone concentration of 1 ppm.

  6. 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...

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

    OpenAIRE

    Buliung Ron; Faulkner Guy; Wong Bonny Yee-Man; Irving Hyacinth

    2011-01-01

    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 th...

  8. Automated prediction of 15N, 13Cα, 13Cβ and 13C' chemical shifts in proteins using a density functional database

    International Nuclear Information System (INIS)

    A database of peptide chemical shifts, computed at the density functional level, has been used to develop an algorithm for prediction of 15N and 13C shifts in proteins from their structure; the method is incorporated into a program called SHIFTS (version 4.0). The database was built from the calculated chemical shift patterns of 1335 peptides whose backbone torsion angles are limited to areas of the Ramachandran map around helical and sheet configurations. For each tripeptide in these regions of regular secondary structure (which constitute about 40% of residues in globular proteins) SHIFTS also consults the database for information about sidechain torsion angle effects for the residue of interest and for the preceding residue, and estimates hydrogen bonding effects through an empirical formula that is also based on density functional calculations on peptides. The program optionally searches for alternate side-chain torsion angles that could significantly improve agreement between calculated and observed shifts. The application of the program on 20 proteins shows good consistency with experimental data, with correlation coefficients of 0.92, 0.98, 0.99 and 0.90 and r.m.s. deviations of 1.94, 0.97, 1.05, and 1.08 ppm for 15N, 13Cα, 13Cβ and 13C', respectively. Reference shifts fit to protein data are in good agreement with 'random-coil' values derived from experimental measurements on peptides. This prediction algorithm should be helpful in NMR assignment, crystal and solution structure comparison, and structure refinement

  9. 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.

  10. 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.

  11. Fragment-based 13C nuclear magnetic resonance chemical shift predictions in molecular crystals: An alternative to planewave methods

    International Nuclear Information System (INIS)

    We assess the quality of fragment-based ab initio isotropic 13C chemical shift predictions for a collection of 25 molecular crystals with eight different density functionals. We explore the relative performance of cluster, two-body fragment, combined cluster/fragment, and the planewave gauge-including projector augmented wave (GIPAW) models relative to experiment. When electrostatic embedding is employed to capture many-body polarization effects, the simple and computationally inexpensive two-body fragment model predicts both isotropic 13C chemical shifts and the chemical shielding tensors as well as both cluster models and the GIPAW approach. Unlike the GIPAW approach, hybrid density functionals can be used readily in a fragment model, and all four hybrid functionals tested here (PBE0, B3LYP, B3PW91, and B97-2) predict chemical shifts in noticeably better agreement with experiment than the four generalized gradient approximation (GGA) functionals considered (PBE, OPBE, BLYP, and BP86). A set of recommended linear regression parameters for mapping between calculated chemical shieldings and observed chemical shifts are provided based on these benchmark calculations. Statistical cross-validation procedures are used to demonstrate the robustness of these fits

  12. 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.

  13. Attainable entanglement of unitary transformed thermal states in liquid-state nuclear magnetic resonance with the chemical shift

    CERN Document Server

    Ota, Y; Ohba, I; Yoshida, N; Mikami, Shuji; Ohba, Ichiro; Ota, Yukihiro; Yoshida, Noriyuki

    2006-01-01

    Recently, Yu, Brown, and Chuang [Phys. Rev. A {\\bf 71}, 032341 (2005)] investigated the entanglement attainable from unitary transformed thermal states in liquid-state nuclear magnetic resonance (NMR). Their research gave an insight into the role of the entanglement in a liquid-state NMR quantum computer. Moreover, they attempted to reveal the role of mixed-state entanglement in quantum computing. However, they assumed that the Zeeman energy of each nuclear spin which corresponds to a qubit takes a common value for all; there is no chemical shift. In this paper, we research a model with the chemical shifts and analytically derive the physical parameter region where unitary transformed thermal states are entangled, by the positive partial transposition (PPT) criterion with respect to any bipartition. We examine the effect of the chemical shifts on the boundary between the separability and the nonseparability, and find it is negligible.

  14. 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.

  15. 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. PMID:26782194

  16. 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.

  17. The study on temporal lobe epilepsy with single-voxel proton MR spectroscopy and chemical shift imaging

    International Nuclear Information System (INIS)

    Objective: To investigate the value of different proton MR spectroscopy techniques including single-voxel spectroscopy (SVS) and chemical shift imaging (CSI) in diagnosing patients with temporal lobe epilepsy. Methods: Sixty cases (40 normal, 20 temporal lobe epilepsy) experienced SVS and CSI. The volume of interest (VOI) of SVS was placed over the anterior hippocampus formation (HF) region, including part of the head and body of the HF. The VOI of CSI encompassed bilateral HF and the head, body and tail of HF. The VOI was divided into 5 voxels from anterior to posterior. The metabolite data of both SVS and CSI were obtained and the ratios of NAA/Cr and NAA/(Cho+Cr) were recorded or calculated. Results: The ipsilateral hippocampus to the seizure of TLE patients had lower ratios of NAA/(Cho+Cr) and NAA/Cr, and the differences compared with those of the normal group and contralateral subgroup were statistically significant (F=41.958, P1HMRS study improved the diagnostic yield of MR evaluation in TLE patients. There was a correlation between the ratio of NAA/(Cho+Cr) and the location of HF. Regional variation must be considered when interpreting proton spectra of the HF. (author)

  18. 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.

  19. Chemical shift assignment of the alternative scaffold protein IscA.

    Science.gov (United States)

    Popovic, Matija; Pastore, Annalisa

    2016-04-01

    The IscA protein (11.5 kDa) is an essential component of the iron sulphur cluster biogenesis machine. In bacteria, the machine components are clustered in operons, amongst which the most important is the isc operon. Bacterial IscA has direct homologues also in eukaryotes. Like the protein IscU, IscA is thought to assist cluster formation as an alternative scaffold protein which receives the cluster before transferring it further to the final acceptors. Several crystal structures have been published. They all report an IscA dimeric form, although the packing of the protomers in the dimers differs amongst structures. No solution studies have currently been reported. Here we report the (1)H, (13)C and (15)N backbone and side-chain chemical shift assignments of the cluster-free E. coli IscA as a starting point for further studies of the structure and functions of this still poorly characterized protein. We show that IscA exists in solution as an equilibrium between different species. Spectrum assignment was thus challenging given the heterogeneous nature of the sample but doable through judicious choice of selective labelling and concentration dependent studies.

  20. 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.

  1. Spin-Correlation Coefficients and Phase-Shift Analysis for p+$^3$He Elastic Scattering

    CERN Document Server

    Daniels, T V; Cesaratto, J M; Clegg, T B; Couture, A H; Karwowski, H J; Katabuchi, T

    2010-01-01

    Angular Distributions for the target spin-dependent observables A$_{0y}$, A$_{xx}$, and A$_{yy}$ have been measured using polarized proton beams at several energies between 2 and 6 MeV and a spin-exchange optical pumping polarized $^3$He target. These measurements have been included in a global phase-shift analysis following that of George and Knutson, who reported two best-fit phase-shift solutions to the previous global p+$^3$He elastic scattering database below 12 MeV. These new measurements, along with measurements of cross-section and beam-analyzing power made over a similar energy range by Fisher \\textit{et al.}, allowed a single, unique solution to be obtained. The new measurements and phase-shifts are compared with theoretical calculations using realistic nucleon-nucleon potential models.

  2. 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...

  3. 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.

  4. A comparison of chemical shift sensitivity of trifluoromethyl tags: optimizing resolution in {sup 19}F NMR studies of proteins

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Libin; Larda, Sacha Thierry; Frank Li, Yi Feng [University of Toronto, UTM, Department of Chemistry (Canada); Manglik, Aashish [Stanford University School of Medicine, Department of Molecular and Cellular Physiology (United States); Prosser, R. Scott, E-mail: scott.prosser@utoronto.ca [University of Toronto, UTM, Department of Chemistry (Canada)

    2015-05-15

    The elucidation of distinct protein conformers or states by fluorine ({sup 19}F) NMR requires fluorinated moieties whose chemical shifts are most sensitive to subtle changes in the local dielectric and magnetic shielding environment. In this study we evaluate the effective chemical shift dispersion of a number of thiol-reactive trifluoromethyl probes [i.e. 2-bromo-N-(4-(trifluoromethyl)phenyl)acetamide (BTFMA), N-(4-bromo-3-(trifluoromethyl)phenyl)acetamide (3-BTFMA), 3-bromo-1,1,1-trifluoropropan-2-ol (BTFP), 1-bromo-3,3,4,4,4-pentafluorobutan-2-one (BPFB), 3-bromo-1,1,1-trifluoropropan-2-one (BTFA), and 2,2,2-trifluoroethyl-1-thiol (TFET)] under conditions of varying polarity. In considering the sensitivity of the {sup 19}F NMR chemical shift to the local environment, a series of methanol/water mixtures were prepared, ranging from relatively non-polar (MeOH:H{sub 2}O = 4) to polar (MeOH:H{sub 2}O = 0.25). {sup 19}F NMR spectra of the tripeptide, glutathione ((2S)-2-amino-4-{[(1R)-1-[(carboxymethyl)carbamoyl] -2-sulfanylethyl]carbamoyl}butanoic acid), conjugated to each of the above trifluoromethyl probes, revealed that the BTFMA tag exhibited a significantly greater range of chemical shift as a function of solvent polarity than did either BTFA or TFET. DFT calculations using the B3LYP hybrid functional and the 6-31G(d,p) basis set, confirmed the observed trend in chemical shift dispersion with solvent polarity.

  5. 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.

  6. 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.

  7. 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.

  8. Anomalous chemical shifts in X-ray photoelectron spectra of sulfur-containing compounds of silver (I) and (II)

    International Nuclear Information System (INIS)

    Highlights: • Ag 3d5/2 binding energy for Ag(II)SO4 is as large as 370.1 eV. • This is the largest value ever measured for a silver (II) compound. • Large shift is connected with the extreme oxidizing nature of Ag(II) species. • Ag(I)2S2O7 exhibits both positive and negative shifts with respect to metallic Ag. • Two distinct Ag(I) sites are responsible for large BE difference of 3.6 eV. - Abstract: Anomalous chemical shifts, i.e. cases when binding energy decreases with the increase of the oxidation state, have been well-documented for selected compounds of silver, and well understood based on analysis of initial- and final-state effects in the XPS spectra. Here we report two examples of even more exotic behaviour of chemical shifts for two silver compounds. The first one is Ag2S2O7 which exhibits both positive and negative substantial shifts with respect to metallic Ag for two distinct Ag(I) sites in its crystal structure, which differ by as much as 3.6 eV. Another is AgSO4, a rare example of oxo silver (II) salt, which exhibits “normal” chemical shift but the Ag 3d5/2 binding energy takes the largest value measured for a silver (II) compound (370.1 eV). This property is connected predominantly with the extremely strongly oxidizing nature of Ag(II) species

  9. 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

    ). 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....... The relativistic effect of Br and I atoms on nuclear shieldings was modeled using the spin-orbit ZORA method. Significant heavy atom shielding effects for the carbon atom directly bonded with bromine and iodine were observed (~ -10 and ~ -30 ppm while the other carbon shifts were practically unaffected...

  10. 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.

  11. Predicting 15N chemical shifts in proteins using the preceding residue-specific individual shielding surfaces from φ, ψi-1, and χ1torsion angles

    International Nuclear Information System (INIS)

    Empirical shielding surfaces are most commonly used to predict chemical shifts in proteins from known backbone torsion angles, φ and ψ. However, the prediction of 15N chemical shifts using this technique is significantly poorer, compared to that for the other nuclei such as 1Hα, 13Cα, and 13Cβ. In this study, we investigated the effects from the preceding residue and the side-chain geometry, χ1, on 15N chemical shifts by statistical methods. For an amino acid sequence XY, the 15N chemical shift of Y is expressed as a function of the amino acid types of X and Y, as well as the backbone torsion angles, φ and ψi-1. Accordingly, 380 empirical 'Preceding Residue Specific Individual (PRSI)' 15N chemical shift shielding surfaces, representing all the combinations of X and Y (except for Y=Pro), were built and used to predict 15N chemical shift from φ and ψi-1. We further investigated the χ1 effects, which were found to account for differences in 15N chemical shifts by ∼5 ppm for amino acids Val, Ile, Thr, Phe, His, Tyr, and Trp. Taking the χ1 effects into account, the χ1-calibrated PRSI shielding surfaces (XPRSI) were built and used to predict 15N chemical shifts for these amino acids. We demonstrated that 15N chemical shift predictions are significantly improved by incorporating the preceding residue and χ1 effects. The present PRSI and XPRSI shielding surfaces were extensively compared with three recently published programs, SHIFTX (Neal et al., 2003), SHIFTS (Xu and Case, 2001 and 2002), and PROSHIFT (Meiler, 2003) on a set of ten randomly selected proteins. A set of Java programs using XPRSI shielding surfaces to predict 15N chemical shifts in proteins were developed and are freely available for academic users at http://www.pronmr.com or by sending email to one of the authors Yunjun Wang

  12. 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

  13. Magnetic activity cycles in solar-like stars: The cross-correlation technique of p-mode frequency shifts

    OpenAIRE

    Regulo, C.; Garcia, R.A.; Ballot, J.

    2016-01-01

    Aims. We aim studying the use of cross-correlation techniques to infer the frequency shifts induced by changing magnetic fields in the p-mode frequencies and provide precise estimation of the error bars. Methods. This technique and the calculation of the associated errors is first tested and validated on the Sun where the p-mode magnetic behaviour is very well known. These validation tests are performed on 6000-day time series of Sun-as-a-star observations delivered by the SoHO spacecraft. Er...

  14. Distinguishing between cystic teratomas and endometriomas of the ovary using chemical shift gradient echo magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Ishijima Hideyuki; Ishizaka Hiroshi; Inoue Tomio [Gunma University Hospital, Gunma (Japan). Depts. of Diagnostic Radiaology and Nuclear Medicine

    1996-02-01

    The purpose of this study was to evaluate the efficacy of chemical shift gradient echo magnetic resonance imaging (MRI) in distinguishing between cystic teratomas and endometriomas of the ovary, using a 1.5 T magnet. The study included 22 patients with 31 ovarian lesions (15 cystic teratomas and 16 endometriomas), which showed high signal intensity on T1-weighted spin echo images. Chemical shift gradient echo images with three different echo times (TE = 2.5, 4.5 and 6.5 ms) were obtained in all cases. Indices were calculated on the basis of the signal intensities of lesions on the chemical shift gradient echo images. All endometriomas had signal intensity indices of less than 2.1, while all cystic teratomas had signal intensity indices of 18.1 or greater. It was concluded that the method used in this study presents the following advantages: the acquisition time is short; it needs no special software; and it does not depend on magnetic field homogeneity. 11 refs., 4 figs.

  15. 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.

  16. Secondary structural analysis of proteins based on 13C chemical shift assignments in unresolved solid-state NMR spectra enhanced by fragmented structure database

    International Nuclear Information System (INIS)

    Magic-angle-spinning solid-state 13C NMR spectroscopy is useful for structural analysis of non-crystalline proteins. However, the signal assignments and structural analysis are often hampered by the signal overlaps primarily due to minor structural heterogeneities, especially for uniformly-13C,15N labeled samples. To overcome this problem, we present a method for assigning 13C chemical shifts and secondary structures from unresolved two-dimensional 13C–13C MAS NMR spectra by spectral fitting, named reconstruction of spectra using protein local structures (RESPLS). The spectral fitting was conducted using databases of protein fragmented structures related to 13Cα, 13Cβ, and 13C′ chemical shifts and cross-peak intensities. The experimental 13C–13C inter- and intra-residue correlation spectra of uniformly isotope-labeled ubiquitin in the lyophilized state had a few broad peaks. The fitting analysis for these spectra provided sequence-specific Cα, Cβ, and C′ chemical shifts with an accuracy of about 1.5 ppm, which enabled the assignment of the secondary structures with an accuracy of 79 %. The structural heterogeneity of the lyophilized ubiquitin is revealed from the results. Test of RESPLS analysis for simulated spectra of five different types of proteins indicated that the method allowed the secondary structure determination with accuracy of about 80 % for the 50–200 residue proteins. These results demonstrate that the RESPLS approach expands the applicability of the NMR to non-crystalline proteins exhibiting unresolved 13C NMR spectra, such as lyophilized proteins, amyloids, membrane proteins and proteins in living cells.

  17. Interval shifts in basophil measures correlate with disease activity in chronic spontaneous urticaria.

    Science.gov (United States)

    Oliver, E T; Sterba, P M; Saini, S S

    2015-05-01

    Chronic spontaneous urticaria (CSU) significantly impacts the quality of life of those affected through symptoms of pruritus and recurrent skin lesions. In active CSU disease, reduced IgE-mediated basophil histamine release (HR) and basopenia are observed. We sought to examine the relationship between interval changes in basophil measures and shifts in patient-reported disease impairment. Simultaneous symptom and basophil evaluations were completed at two sequential study visits, and interval changes in measures were compared between visits for each subject (n = 38). These measures included Skindex-29, current itch and hives scores, total leukocyte histamine content (an indirect measure of blood basophil presence), and basophil HR in response to anti-IgE and formyl-methionine-leucine-phenylalanine. Overall, interval improvements in disease measures in CSU subjects were associated with increased basophil numbers (total leukocyte histamine content) and IgE-mediated HR. This suggests these measures are potential biomarkers for CSU disease improvement and further implicates a role for basophils in CSU. PMID:25631394

  18. 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

  19. Bonding and chemical shifts in aluminosilicate glasses: importance of Madelung effects

    CERN Document Server

    Cruguel, H; Kerjan, O; Bart, F; Gautier-Soyer, M

    2003-01-01

    A detailed study of the XPS binding energy shifts of Si 2p, O 1s and Zr 3d in a series of aluminosilicate glasses (a three oxide glass: SiO sub 2 -Al sub 2 O sub 3 -CaO, three four-oxide glasses: SiO sub 2 -Al sub 2 O sub 3 -CaO-TiO sub 2 , ZrO sub 2 or CeO sub 2 , along with a six-oxide glass SiO sub 2 -Al sub 2 O sub 3 -CaO-TiO sub 2 -ZrO sub 2 -CeO sub 2) is presented. Their composition is such that these glasses have the same mean electronegativity, so that no changes in the atomic charges is expected. The binding energy shifts are interpreted in terms of initial and final state effects, and the balance of charge transfer contribution and electrostatic effects is discussed. Referred to the ternary glass, the binding energy shifts of the Si 2p, O 1s and Zr 3d lines in the complex glasses are due to an initial state effect, as the extraatomic relaxation is similar along the glass series. These shifts originate from electrostatic Madelung effects, likely coming from a structural change induced by the presenc...

  20. Differential neural correlates of set-shifting in the bingeing-purging and restrictive subtypes of anorexia nervosa : An fMRI study

    NARCIS (Netherlands)

    Van Autreve, Sara; De Baene, W.; Baeken, Chris; van Heeringen, Kees; Vancayseele, Nikita; Vervaet, Myriam

    2016-01-01

    In this study, possible differences in the neural correlates of set-shifting abilities between the restrictive (AN-R) and bingeing/purging (AN-BP) subtypes of anorexia nervosa have been explored. Three groups of participants performed a set-shifting task during functional magnetic resonance imaging:

  1. 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.

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

    Science.gov (United States)

    Goudarzi, Nasser

    2016-04-01

    In this work, two new and powerful chemometrics methods are applied for the modeling and prediction of the 19F 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 19F 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.

  3. Conventional Quantum Chemical Correlation Energy versus Density-Functional Correlation Energy

    OpenAIRE

    Gross, E.K.U.; Petersilka, M.; Grabo, T.

    1995-01-01

    We analyze the difference between the correlation energy as defined within the conventional quantum chemistry framework and its namesake in density-functional theory. Both quantities are rigorously defined concepts; one finds that $E_c^{QC} \\geq E_c^{DFT}$. We give numerical and analytical arguments suggesting that the numerical difference between the two rigorous quantities is small. Finally, approximate density functional correlation energies resulting from some popular correlation energy f...

  4. Conventional quantum chemical correlation energy versus density-functional correlation energy

    CERN Document Server

    Gross, Eberhard K U; Grabo, T

    1995-01-01

    We analyze the difference between the correlation energy as defined within the conventional quantum chemistry framework and its namesake in density-functional theory. Both quantities are rigorously defined concepts; one finds that E_c^{QC} \\geq E_c^{DFT}. We give numerical and analytical arguments suggesting that the numerical difference between the two rigorous quantities is small. Finally, approximate density functional correlation energies resulting from some popular correlation energy functionals are compared with the conventional quantum chemistry values.

  5. Associations between neural correlates of visual stimulus processing and set-shifting in ill and recovered women with anorexia nervosa.

    Science.gov (United States)

    Sultson, Hedvig; van Meer, Floor; Sanders, Nicole; van Elburg, Annemarie A; Danner, Unna N; Hoek, Hans W; Adan, Roger A H; Smeets, Paul A M

    2016-09-30

    Women ill with anorexia nervosa (AN) have been shown to exhibit altered cognitive functioning, particularly poor set-shifting (SS). In this study, we investigated whether brain activation in frontal and parietal regions during visual stimulus processing correlates with SS ability. Women currently ill with AN (AN; N=14), recovered women (REC; N=14) and healthy controls (HC; N=15), viewed alternating blocks of food and non-food pictures during functional magnetic resonance imaging (fMRI). The Berg's Card Sorting Task was completed outside the scanner to measure SS. A priori regions of interest (ROIs) were defined in frontal and parietal regions. The activation during visual stimulus processing in several ROIs correlated positively with poor SS ability in REC, particularly in the left dorsal anterior cingulate cortex (dACC). The correlations with poor SS ability were opposite in AN patients, particularly in the right dACC. These findings underscore that addressing heightened levels of cognitive control associated with higher frontal activation could reduce cognitive inflexibility in recovered women. In AN, greater activation in frontal and parietal regions might be necessary to perform at normal levels during various tasks. Thus, weight restoration could be necessary for AN patients prior to addressing cognitive inflexibility. PMID:27518327

  6. 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,

  7. Magnetic activity cycles in solar-like stars: The cross-correlation technique of p-mode frequency shifts

    CERN Document Server

    Regulo, C; Ballot, J

    2016-01-01

    Aims. We aim studying the use of cross-correlation techniques to infer the frequency shifts induced by changing magnetic fields in the p-mode frequencies and provide precise estimation of the error bars. Methods. This technique and the calculation of the associated errors is first tested and validated on the Sun where the p-mode magnetic behaviour is very well known. These validation tests are performed on 6000-day time series of Sun-as-a-star observations delivered by the SoHO spacecraft. Errors of the frequency shifts are quantified through Monte Carlo simulations. The same methodology is then applied to three solar-like oscillating stars: HD 49933, observed by CoRoT, as well as KIC 3733735 and KIC 7940546 observed by Kepler. Results. We first demonstrate the reliability of the error bars computed with the Monte Carlo simulations using the Sun. From the three analyzed stars we confirm the presence of a magnetic activity cycle with this methodology in HD 49933 and we unveil seismic signature of on going magn...

  8. CORRELATION STUDIES BETWEEN PHYSICO-CHEMICAL, CHEMICAL AND NUTRIENT UPTAKES OF PADDY IN PHOSPHORUS RICH VERTISOLS

    OpenAIRE

    V Siva Jyothi; T Giridhara Krishna; P.KAVITHA; Srinivasa Reddy, M.

    2014-01-01

    A field experiment was conducted in paddy having high soil available P vertisols under K.C. Canal ayacut at Regional Agricultural Research Station, Nandyal, Andhra Pradesh. The correlation studies revealed that there exist a positive strong correlation between agronomic characters at different stages with the yield. pH and EC was positively correlate with yield except pH at panicle initiation stage is non significantly correlate with yield. The available nitrogen at tillering (r= 0.446), pani...

  9. 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.

  10. Gradient-echo in-phase and opposed-phase chemical shift imaging: Role in evaluating bone marrow

    International Nuclear Information System (INIS)

    Chemical shift imaging (CSI) provides valuable information for assessing the bone marrow, while adding little to total examination time. In this article, we review the uses of CSI for evaluating bone marrow abnormalities. CSI can be used for differentiating marrow-replacing lesions from a range of non-marrow-replacing processes, although the sequence is associated with technical limitations and pitfalls. Particularly at 3 T, susceptibility artefacts are prevalent, and optimal technical parameters must be implemented with appropriate choices for echo times

  11. A multiple pulse zero crossing NMR technique, and its application to F-19 chemical shift measurements in solids

    Science.gov (United States)

    Burum, D. P.; Elleman, D. D.; Rhim, W.-K.

    1978-01-01

    A simple multiple-pulse 'zero crossing technique' for accurately determining the first moment of a solid-state NMR spectrum is introduced. This technique was applied to obtain the F-19 chemical shift versus pressure curves up to 5 kbar for single crystals of CaF2 (0.29 + or - 0.02 ppm/kbar) and BaF2 (0.62 + or - 0.05 ppm/kbar). Results at ambient temperature and pressure are also reported for a number of other fluorine compounds. Because of its high data rate, this technique is potentially several orders of magnitude more sensitive than similar CW methods.

  12. 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.

  13. 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.

  14. Correlation analyses between volatiles and glucosinolates show no evidence for chemical defense signaling in Brassica rapa

    Directory of Open Access Journals (Sweden)

    Florian Paul Schiestl

    2014-04-01

    Full Text Available Positive correlations between volatile organic compounds (VOCs and defense chemicals indicate signaling of defense status. Such aposematic signaling has been hypothesized to be widespread in plants, however, it has up to now only been shown for visual signals. Correlations between identical compounds in different plant tissues, on the other hand, can be informative about the (co-regulation of their biosynthesis or emission. Here I use Brassica rapa to investigate 1 correlations between identical metabolites (volatiles, glucosinolates in leaf and flower tissue, and 2 correlations between volatiles and glucosinolates in the same plant organs (flowers and leaves. Whereas the amounts of many glucosinolates were positively correlated in leaves and flower tissue, identical leaf and floral VOCs showed no such correlations, indicating independent regulation of emission. None of the leaf or flower volatiles showed positive correlations with the two major glucosinolates (gluconapin, glucobrassicanapin or the sum of all glucosinolates in either leaves or flowers. Some VOCs, however, showed positive correlations with minor glucosinolates which, however, represented less than one percent of the total amounts of glucosinolates. Some leaf monoterpenes showed negative associations with gluconapin. The lack of consistent positive correlations between VOCs and major defense compounds suggests that plants do not chemically signal their defense status. This could be adaptive as it may avoid eavesdropping by specialist herbivores to locate their host plants. Negative correlations likely indicate chemical trade-offs in the synthesis of secondary metabolites.

  15. 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.

  16. 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.

  17. 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+...

  18. Molecular structure and vibrational bands and 13C chemical shift assignments of both enmein-type diterpenoids by DFT study

    Science.gov (United States)

    Wang, Tao; Wu, Yi fang; Wang, Xue liang

    2014-01-01

    We report here theoretical and experimental studies on the molecular structure and vibrational and NMR spectra of both natural enmein type diterpenoids molecule (6, 7-seco-ent-kaurenes enmein type), isolated from the leaves of Isodon japonica (Burm.f.) Hara var. galaucocalyx (maxin) Hara. The optimized geometry, total energy, NMR chemical shifts and vibrational wavenumbers of epinodosinol and epinodosin have been determined using B3LYP method with 6-311G (d,p) basis set. A complete vibrational assignment is provided for the observed IR spectra of studied compounds. The calculated wavenumbers and 13C c.s. are in an excellent agreement with the experimental values. Quantum chemical calculations at the B3LYP/6-311G (d,p) level of theory have been carried out on studied compounds to obtain a set of molecular electronic properties (MEP,HOMO, LUMO and gap energies ΔEg). Electrostatic potential surfaces have been mapped over the electron density isosurfaces to obtain information about the size, shape, charge density distribution and chemical reactivity of the molecules.

  19. Backbone and stereospecific (13)C methyl Ile (δ1), Leu and Val side-chain chemical shift assignments of Crc.

    Science.gov (United States)

    Sharma, Rakhi; Sahu, Bhubanananda; Ray, Malay K; Deshmukh, Mandar V

    2015-04-01

    Carbon catabolite repression (CCR) allows bacteria to selectively assimilate a preferred compound among a mixture of several potential carbon sources, thus boosting growth and economizing the cost of adaptability to variable nutrients in the environment. The RNA-binding catabolite repression control (Crc) protein acts as a global post-transcriptional regulator of CCR in Pseudomonas species. Crc triggers repression by inhibiting the expression of genes involved in transport and catabolism of non-preferred substrates, thus indirectly favoring assimilation of preferred one. We report here a nearly complete backbone and stereospecific (13)C methyl side-chain chemical shift assignments of Ile (δ1), Leu and Val of Crc (~ 31 kDa) from Pseudomonas syringae Lz4W. PMID:24496608

  20. Reliable resonance assignments of selected residues of proteins with known structure based on empirical NMR chemical shift prediction

    Science.gov (United States)

    Li, Da-Wei; Meng, Dan; Brüschweiler, Rafael

    2015-05-01

    A robust NMR resonance assignment method is introduced for proteins whose 3D structure has previously been determined by X-ray crystallography. The goal of the method is to obtain a subset of correct assignments from a parsimonious set of 3D NMR experiments of 15N, 13C labeled proteins. Chemical shifts of sequential residue pairs are predicted from static protein structures using PPM_One, which are then compared with the corresponding experimental shifts. Globally optimized weighted matching identifies the assignments that are robust with respect to small changes in NMR cross-peak positions. The method, termed PASSPORT, is demonstrated for 4 proteins with 100-250 amino acids using 3D NHCA and a 3D CBCA(CO)NH experiments as input producing correct assignments with high reliability for 22% of the residues. The method, which works best for Gly, Ala, Ser, and Thr residues, provides assignments that serve as anchor points for additional assignments by both manual and semi-automated methods or they can be directly used for further studies, e.g. on ligand binding, protein dynamics, or post-translational modification, such as phosphorylation.

  1. 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. PMID:27488185

  2. 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.

  3. 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.

  4. The protein amide {sup 1}H{sup N} chemical shift temperature coefficient reflects thermal expansion of the N-H{center_dot}{center_dot}{center_dot}O=C hydrogen bond

    Energy Technology Data Exchange (ETDEWEB)

    Hong Jingbo; Jing Qingqing; Yao Lishan, E-mail: yaols@qibebt.ac.cn [Chinese Academy of Sciences, Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology (China)

    2013-01-15

    The protein amide {sup 1}H{sup N} chemical shift temperature coefficient can be determined with high accuracy by recording spectra at different temperatures, but the physical mechanism responsible for this temperature dependence is not well understood. In this work, we find that this coefficient strongly correlates with the temperature coefficient of the through-hydrogen-bond coupling, {sup 3h}J{sub NC Prime }, based on NMR measurements of protein GB3. Parallel tempering molecular dynamics simulation suggests that the hydrogen bond distance variation at different temperatures/replicas is largely responsible for the {sup 1}H{sup N} chemical shift temperature dependence, from which an empirical equation is proposed to predict the hydrogen bond thermal expansion coefficient, revealing responses of individual hydrogen bonds to temperature changes. Different expansion patterns have been observed for various networks formed by {beta} strands.

  5. 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.

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

    International Nuclear Information System (INIS)

    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 % 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.)

  7. 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.

  8. Chemical shift measurements of chlorine K X-ray spectra using a high-resolution PIXE system

    International Nuclear Information System (INIS)

    A high-efficiency high-resolution wavelength-dispersive spectrograph with a von-Hamos configuration was developed for chemical state identification of elements in environmental samples using PIXE analysis. To evaluate the performance of this system, chlorine K X-ray spectra for NaCl, NH4Cl and polyvinylchloride (PVC) targets were measured and compared. Also, to study the applicability to environmental mixed samples, mixtures of NaCl and NH4Cl with different mixing ratios were measured. Through observation of Cl Kα1 X-ray from NaCl, the energy resolution of the system was determined to be 1.1 eV. For the NaCl sample, a Kβx line was observed at an energy, which is higher than that of the Kβ main peak by 2 eV, whereas no Kβx emission was observed for the NH4Cl sample. The chemical shift of the Kβ main peak for PVC relative to that for NaCl was about 1.2 eV. For NaCl-NH4Cl mixture targets, the relative intensity of Kβx satellite to the Kβ main line provided an indication of mixing ratio. Energies and relative intensity of Cl Kβ X-ray satellites for NaCl and NH4Cl samples calculated by a simple molecular-orbital method agreed only qualitatively with the experimental results

  9. Correlation between apparent electrical conductivity and chemical and physical attributes of a Rhodic Hapludox

    Directory of Open Access Journals (Sweden)

    Eduardo Leonel Bottega

    2015-07-01

    Full Text Available Precision agriculture has been used as an important technique for localized management of soil fertility. Therefore, it is essential to characterize the spatial variability of chemical and physical attributes of the soil by sampling can represent such variations. This study aimed to analyze the correlation between the apparent electrical conductivity with the chemical and physical attributes of an Rhodic Hapludox. The work was performed on a property located in the Brazilian Cerrado. In an area of 90 hectare were collected 181 georeferenced soil samples at depths from 0.00 to 0.20 meters. The same sites and removal of samples were made apparent electrical conductivity of the soil. The samples were sent to the laboratory to perform the physical and chemical analysis. Were selected randomly sampling 30 points and calculated the Pearson correlation coefficient between the variable physical, chemical and apparent soil electrical conductivity. There was no significant correlation between the apparent electrical conductivity with the soil physical attributes. There was a significant positive correlation of apparent electrical conductivity of the soil at a depth of 0.20 m with the chemical attributes match, remaining phosphorus and zinc.

  10. The correlation of chemical characteristics of an oil to dispersant effectiveness

    Energy Technology Data Exchange (ETDEWEB)

    Fingas, M.F.; Wang, Z.D.; Fieldhouse, B.G.; Smith, P. [Environment Canada, Ottawa, ON (Canada). River Road Environmental Technology Centre

    2003-07-01

    The effectiveness of a dispersant is defined as the amount of oil that the dispersant puts into the water column compared to what is dispersed. The effectiveness of the dispersant depends mostly on the composition of the oil, followed by sea energy and the amount of dispersant applied. Other significant factors include the state of oil weathering, type of dispersant, temperature, and salinity of the water. Oil properties and dispersant effectiveness can be correlated to determine the amount of oil dispersion. The correlation can be used to determine which oil properties would inhibit or facilitate oil dispersion. This paper presents thirteen newly developed models that predict chemical dispersibility. They were created from data on 295 oils and 29 of their chemical and physical properties. The key parameter was dispersibility of Corexit 9500 in the swirling flask apparatus. Each model varies significantly in terms of input parameters and in statistical quality, but all can be used to predict the chemical dispersibility of oils given the required input parameters. Many essentials of chemical dispersions were discovered during the development of these models. For example, small n-alkanes were found to be prone to dispersion. It was shown that some parameters, such as chemical composition indicators, are very good predictors of chemical dispersibility, while physical properties were found to be poor predictors of chemical dispersibility. Wax content, interfacial tension, and flash point were among the properties that did not help in predicting dispersibility. 10 refs., 8 tabs., 26 figs.

  11. 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.

  12. The value of 15-minute delayed contrast-enhanced CT to differentiate hyperattenuating adrenal masses compared with chemical shift MR imaging

    Energy Technology Data Exchange (ETDEWEB)

    Koo, Hyun Jung; Choi, Hyuck Jae; Cho, Kyoung-Sik [Asan Medical Center, University of Ulsan College of Medicine, Department of Radiology and Research Institute of Radiology, Seoul (Korea, Republic of); Kim, Hwa Jung; Kim, Sun-Ok [Asan Medical Center, University of Ulsan College of Medicine, Cancer Center, Department of Clinical Epidemiology and Biostatistics, Seoul (Korea, Republic of)

    2014-06-15

    To investigate the diagnostic performance of 15-min delayed contrast-enhanced computed tomography (15-DECT) compared with that of chemical shift magnetic resonance (CSMR) imaging in differentiating hyperattenuating adrenal masses and to perform subgroup analysis in underlying malignancy and non-malignancy. This study included 478 adrenal masses in 453 patients examined with 15-DECT and 235 masses in 217 patients examined with CSMR. Relative percentage washout (RPW) and absolute percentage washout (APW) on 15-DECT, and signal intensity index (SII) and adrenal-to-spleen ratio (ASR) on CSMR were measured. Sensitivity, specificity and accuracy of 15-DECT and CSMR were analysed for characterisation of adrenal adenoma. Subgroup analyses were performed in patients with and without underlying malignancy. Attenuation and size of the masses on unenhanced CT correlated with the risk of non-adenoma. RPW calculated from 15-DECT showed the highest diagnostic performance for characterising hyperattenuating adrenal masses regardless of underlying malignancy, and the sensitivity, specificity and accuracy were 91.7 %, 74.8 % and 88.1 %, respectively in all patients. The risk of non-adenoma increased approximately threefold as mass size increased 1 cm or as its attenuation value increased by 10 Hounsfield units. 15-DECT was more accurate than CSMR in characterising hyperattenuating adrenal masses regardless of underlying malignancy. (orig.)

  13. Ultrafast magnetic-resonance-imaging velocimetry of liquid-liquid systems: overcoming chemical-shift artifacts using compressed sensing.

    Science.gov (United States)

    Tayler, Alexander B; Benning, Martin; Sederman, Andrew J; Holland, Daniel J; Gladden, Lynn F

    2014-06-01

    We present simultaneous measurement of dispersed and continuous phase flow fields for liquid-liquid systems obtained using ultrafast magnetic resonance imaging. Chemical-shift artifacts, which are otherwise highly problematic for this type of measurement, are overcome using a compressed sensing based image reconstruction algorithm that accounts for off-resonant signal components. This scheme is combined with high-temporal-resolution spiral imaging (188 frames per second), which is noted for its robustness to flow. It is demonstrated that both quantitative signal intensity and phase preconditioning are preserved throughout the image reconstruction algorithm. Measurements are acquired of oil droplets of varying viscosity rising through stagnant water. From these data it is apparent that the internal droplet flow fields are heavily influenced by the droplet shape oscillations, and that the accurate modeling of droplet shape is of critical importance in the modeling of droplet-side hydrodynamics. The application of the technique to three-component systems is also demonstrated, as is the measurement of local concentration maps of a mutually soluble species (acetone in polydimethylsiloxane-water).

  14. Effect of spectra recording conditions on the example of chemical shifts calculation in CMR spectra of 1-pentylbenzoylformate

    OpenAIRE

    Mizyuk, Volodymyr; Shibanov, Volodymyr

    2011-01-01

    The concept of "compatible" and "incompatible" CMR spectra has been introduced. Application of compatibility increments (IC) allows to calculate the chemical shifts of C and C3 atoms of pentyloxyl fragment in 1-pentylbenzoylformate with a sufficiently good accuracy. Введено поняття "сумісних " і "несумісних " ЯМР спектрів. Застосування "інкрементів узгодження " дало можливість з достатньою точністю розрахувати хімічні зсуви атомів С2 і С пентилоксильного фрагменту в 1-пентилбензоїлформіаті....

  15. 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.

  16. 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.

  17. 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

    2012-02-21

    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. PMID:22241243

  18. Accuracy of chemical shift MR imaging in diagnosing indeterminate bone marrow lesions in the pelvis: review of a single institution's experience

    International Nuclear Information System (INIS)

    To re-assess the accuracy of chemical shift imaging in diagnosing indeterminate bone marrow lesions as benign or malignant. We retrospectively reviewed our experience with MR imaging of the pelvis to assess the accuracy of chemical shift imaging in distinguishing benign from malignant bone lesions. Two musculoskeletal radiologists retrospectively reviewed all osseous lesions biopsied since 2006, when chemical shift imaging was added to our routine pelvic imaging protocol. Study inclusion criteria required (1) MR imaging of an indeterminate bone marrow lesion about the pelvis and (2) subsequent histologic confirmation. The study group included 50 patients (29 male, 21 female) with an average age of 67 years (range, 41-89 years). MR imaging results were evaluated using biopsy results as the ''gold standard.'' There were 27 malignant and 23 benign lesions. Chemical shift imaging using an opposed-phase signal loss criteria of less than 20 % to indicate a malignant lesion, correctly diagnosed 27/27 malignant lesions and 14/23 benign lesions, yielding a 100 % sensitivity, 61 % specificity, 75 % PPV, 100 % NPV, and 82 % accuracy. The area under the receiver operator characteristic (ROC) curve was 0.88. The inter-rater and intra-rater agreement K values were both 1.0. Chemical shift imaging is a useful adjunct MR technique to characterize focal and diffuse marrow abnormalities on routine non-contrast pelvic imaging. It is highly sensitive in identifying malignant disease. Despite its lower specificity, the need for biopsy could be eliminated in more than 60 % of patients with benign disease. (orig.)

  19. Accuracy of chemical shift MR imaging in diagnosing indeterminate bone marrow lesions in the pelvis: review of a single institution's experience

    Energy Technology Data Exchange (ETDEWEB)

    Kohl, Chad A. [Mayo Clinic, Department of Radiology, Phoenix, AZ (United States); Radiology Ltd., Tucson, AZ (United States); Chivers, F.S.; Lorans, Roxanne; Roberts, Catherine C.; Kransdorf, Mark J. [Mayo Clinic, Department of Radiology, Phoenix, AZ (United States)

    2014-08-15

    To re-assess the accuracy of chemical shift imaging in diagnosing indeterminate bone marrow lesions as benign or malignant. We retrospectively reviewed our experience with MR imaging of the pelvis to assess the accuracy of chemical shift imaging in distinguishing benign from malignant bone lesions. Two musculoskeletal radiologists retrospectively reviewed all osseous lesions biopsied since 2006, when chemical shift imaging was added to our routine pelvic imaging protocol. Study inclusion criteria required (1) MR imaging of an indeterminate bone marrow lesion about the pelvis and (2) subsequent histologic confirmation. The study group included 50 patients (29 male, 21 female) with an average age of 67 years (range, 41-89 years). MR imaging results were evaluated using biopsy results as the ''gold standard.'' There were 27 malignant and 23 benign lesions. Chemical shift imaging using an opposed-phase signal loss criteria of less than 20 % to indicate a malignant lesion, correctly diagnosed 27/27 malignant lesions and 14/23 benign lesions, yielding a 100 % sensitivity, 61 % specificity, 75 % PPV, 100 % NPV, and 82 % accuracy. The area under the receiver operator characteristic (ROC) curve was 0.88. The inter-rater and intra-rater agreement K values were both 1.0. Chemical shift imaging is a useful adjunct MR technique to characterize focal and diffuse marrow abnormalities on routine non-contrast pelvic imaging. It is highly sensitive in identifying malignant disease. Despite its lower specificity, the need for biopsy could be eliminated in more than 60 % of patients with benign disease. (orig.)

  20. Enthalpy-entropy correlations as chemical guides to unravel self-assembly processes.

    Science.gov (United States)

    Piguet, Claude

    2011-08-28

    Intermolecular connections play a crucial role in biology (recognition, signalling, binding), in physics (material cohesion) and in chemistry ((supra)molecular engineering). While a phenomenological thermodynamic free-energy approach for modelling self-assemblies is now at hand, a more satisfying description based on the chemically-intuitive enthalpic and entropic contributions remains elusive. On the other hand, the innumerable reports of empirical enthalpy/entropy correlations characterizing intermolecular interactions justify a questioning about the emergence and exploitation of an apparent 'fourth law of thermodynamics', which could provide a simple manipulation of intermolecular binding processes. This tutorial Perspective aims at highlighting the current level of non-quantum rationalization of enthalpy-entropy correlations and their chemical consequences on the tuning and on the programming of intermolecular interactions in pure materials, and in diluted solutions. PMID:21629958

  1. Spectroscopic and Ab Initio Investigation of C-H⋅⋅⋅N Hydrogen-Bonded Complexes of Fluorophenylacetylenes: Frequency Shifts and Correlations.

    Science.gov (United States)

    Dey, Arghya; Mondal, Sohidul Islam; Sen, Saumik; Patwari, G Naresh

    2016-08-18

    The C-H⋅⋅⋅N hydrogen-bonded complexes of several fluorophenyacetylenes with ammonia and methylamine were characterized by a redshift in the acetylenic C-H stretching vibration of the phenylacetylene moiety. These redshifts were linearly correlated with the stabilization energies calculated at the CCSD(T)/CBS//MP2-aug-cc-pVDZ level. Analysis of various components of the interaction energy indicated that the observed redshifts were weakly correlated with the electrostatic component. The weaker linear correlation between the frequency shifts and the electrostatic component between two data sets can perhaps be attributed to the marginal differences in the Stark tuning rate and zero-field shifts. The induction and exchange-repulsion components were linearly correlated. However, the dispersion component depends on the nature of the hydrogen-bond acceptor and shows a quantum jump when the hydrogen-bond acceptor is changed from ammonia to methylamine. The observed linear correlation between the redshifts in the C-H stretching frequencies and the total stabilization energies is due to mutual cancellation of deviations from linearity between various components. PMID:27146197

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Multilayer MoS2 prepared by one-time and repeated chemical vapor depositions: anomalous Raman shifts and transistors with high ON/OFF ratio

    Science.gov (United States)

    Wu, Chong-Rong; Chang, Xiang-Rui; Chang, Shu-Wei; Chang, Chung-En; Wu, Chao-Hsin; Lin, Shih-Yen

    2015-11-01

    We show that multilayer molybdenum disulfide (MoS2) grown with the chemical vapor deposition (CVD) may exhibit quite distinct behaviors of Raman shifts from those of exfoliated ones. The anomalous Raman shifts depend on CVD growth modes and are attributed to the modified dielectric screening and interlayer coupling of MoS2 in various growth conditions. With repeated CVD growths, we demonstrated the precise control over the layer number of MoS2. A decently large drain current, high ON/OFF ratio of 105, and enhanced field-effect mobility can be achieved in transistors fabricated on the six-layer MoS2.

  8. Cardiac high-energy phosphate metabolism alters with age as studied in 196 healthy males with the help of 31-phosphorus 2-dimensional chemical shift imaging.

    Directory of Open Access Journals (Sweden)

    Regina Esterhammer

    Full Text Available Recently published studies have elucidated alterations of mitochondrial oxidative metabolism during ageing. The intention of the present study was to evaluate the impact of ageing on cardiac high-energy phosphate metabolism and cardiac function in healthy humans. 31-phosphorus 2-dimensional chemical shift imaging (31P 2D CSI and echocardiography were performed in 196 healthy male volunteers divided into groups of 20 to 40 years (I, n = 43, 40 to 60 years (II, n = 123 and >60 years (III, n = 27 of age. Left ventricular PCr/β-ATP ratio, myocardial mass (MM, ejection fraction and E/A ratio were assessed. Mean PCr/β-ATP ratios were significantly different among the three groups of volunteers (I, 2.10 ± 0.37; II, 1.77 ± 0.37; III, 1.45 ± 0.28; all p<0.001. PCr/β-ATP ratios were inversely related to age (r(2  =  -0.25; p<0.001 with a decrease from 2.65 by 0.02 per year of ageing. PCr/β-ATP ratios further correlated with MM (r =  -0.371; p<0.001 and E/A ratios (r = 0.213; p<0.02. Moreover, E/A ratios (r =  -0.502, p<0.001, MM (r = 0.304, p<0.001, glucose-levels (r = 0.157, p<0.05 and systolic blood pressure (r = 0.224, p<0.005 showed significant correlations with age. The ejection fraction did not significantly differ between the groups. This study shows that cardiac PCr/β-ATP ratios decrease moderately with age indicating an impairment of mitochondrial oxidative metabolism due to age. Furthermore, MM increases, and E/A ratio decreases with age. Both correlate with left-ventricular PCr/β-ATP ratios. The findings of the present study confirm numerous experimental studies showing an impairment of cardiac mitochondrial function with age.

  9. Cardiac high-energy phosphate metabolism alters with age as studied in 196 healthy males with the help of 31-phosphorus 2-dimensional chemical shift imaging.

    Science.gov (United States)

    Esterhammer, Regina; Klug, Gert; Wolf, Christian; Mayr, Agnes; Reinstadler, Sebastian; Feistritzer, Hans-Josef; Metzler, Bernhard; Schocke, Michael F H

    2014-01-01

    Recently published studies have elucidated alterations of mitochondrial oxidative metabolism during ageing. The intention of the present study was to evaluate the impact of ageing on cardiac high-energy phosphate metabolism and cardiac function in healthy humans. 31-phosphorus 2-dimensional chemical shift imaging (31P 2D CSI) and echocardiography were performed in 196 healthy male volunteers divided into groups of 20 to 40 years (I, n = 43), 40 to 60 years (II, n = 123) and >60 years (III, n = 27) of age. Left ventricular PCr/β-ATP ratio, myocardial mass (MM), ejection fraction and E/A ratio were assessed. Mean PCr/β-ATP ratios were significantly different among the three groups of volunteers (I, 2.10 ± 0.37; II, 1.77 ± 0.37; III, 1.45 ± 0.28; all p<0.001). PCr/β-ATP ratios were inversely related to age (r(2)  =  -0.25; p<0.001) with a decrease from 2.65 by 0.02 per year of ageing. PCr/β-ATP ratios further correlated with MM (r =  -0.371; p<0.001) and E/A ratios (r = 0.213; p<0.02). Moreover, E/A ratios (r =  -0.502, p<0.001), MM (r = 0.304, p<0.001), glucose-levels (r = 0.157, p<0.05) and systolic blood pressure (r = 0.224, p<0.005) showed significant correlations with age. The ejection fraction did not significantly differ between the groups. This study shows that cardiac PCr/β-ATP ratios decrease moderately with age indicating an impairment of mitochondrial oxidative metabolism due to age. Furthermore, MM increases, and E/A ratio decreases with age. Both correlate with left-ventricular PCr/β-ATP ratios. The findings of the present study confirm numerous experimental studies showing an impairment of cardiac mitochondrial function with age. PMID:24940736

  10. Differential Neural Correlates of Set-Shifting in the Bingeing-Purging and Restrictive Subtypes of Anorexia Nervosa: An fMRI Study.

    Science.gov (United States)

    Van Autreve, Sara; De Baene, Wouter; Baeken, Chris; van Heeringen, Kees; Vancayseele, Nikita; Vervaet, Myriam

    2016-07-01

    In this study, possible differences in the neural correlates of set-shifting abilities between the restrictive (AN-R) and bingeing/purging (AN-BP) subtypes of anorexia nervosa have been explored. Three groups of participants performed a set-shifting task during functional magnetic resonance imaging: patients with AN-R (N = 16), AN-BP (N = 13) and healthy control participants (N = 15). As in a typical set-shifting experiment, participants had to switch between two easy tasks (i.e. 'Is the presented number odd/even' or 'Is the presented number smaller/larger than 5'). The trials in which the task was repeated (repeat trials) were compared with trials in which the task was switched (switch trials). With regards to the level of task performance, no significant group differences could be established. However, when comparing switch specific brain activity across study groups, a stronger activation was found in the insula and the precuneus in AN-R when compared to AN-BP and HC. These results suggest that the both subtypes of AN might have different neurobiological correlates, and thus, might benefit from different treatment approaches. Copyright © 2016 John Wiley & Sons, Ltd and Eating Disorders Association. PMID:26856396

  11. The limits of local correlation theory: electronic delocalization and chemically smooth potential energy surfaces.

    Science.gov (United States)

    Subotnik, Joseph E; Sodt, Alex; Head-Gordon, Martin

    2008-01-21

    Local coupled-cluster theory provides an algorithm for measuring electronic correlation quickly, using only the spatial locality of localized electronic orbitals. Previously, we showed [J. Subotnik et al., J. Chem. Phys. 125, 074116 (2006)] that one may construct a local coupled-cluster singles-doubles theory which (i) yields smooth potential energy surfaces and (ii) achieves near linear scaling. That theory selected which orbitals to correlate based only on the distances between the centers of different, localized orbitals, and the approximate potential energy surfaces were characterized as smooth using only visual identification. This paper now extends our previous algorithm in three important ways. First, locality is now based on both the distances between the centers of orbitals as well as the spatial extent of the orbitals. We find that, by accounting for the spatial extent of a delocalized orbital, one can account for electronic correlation in systems with some electronic delocalization using fast correlation methods designed around orbital locality. Second, we now enforce locality on not just the amplitudes (which measure the exact electron-electron correlation), but also on the two-electron integrals themselves (which measure the bare electron-electron interaction). Our conclusion is that we can bump integrals as well as amplitudes, thereby gaining a tremendous increase in speed and paradoxically increasing the accuracy of our LCCSD approach. Third and finally, we now make a rigorous definition of chemical smoothness as requiring that potential energy surfaces not support artificial maxima, minima, or inflection points. By looking at first and second derivatives from finite difference techniques, we demonstrate complete chemical smoothness of our potential energy surfaces (bumping both amplitudes and integrals). These results are significant both from a theoretical and from a computationally practical point of view. PMID:18205484

  12. Mapping dry matter production of Tifton 85 and its correlation with the soil chemical properties

    Directory of Open Access Journals (Sweden)

    Osmar Henrique de Castro Pias

    2015-07-01

    Full Text Available The creation of cattle in the semi extensive system has currently been the most used by the farmers on Brazil, however, problems such as degradation of pastures are committing this production system, reducing the production of forager and consequently the profitability of producers. In this sense, the aim of this study was to perform the mapping of the dry mass production, nitrogen accumulation, phosphorus and potassium in the Tifton 85, and evaluate their correlations with the chemical attributes in different layers of the soil profile. The study was carried out in an area of 4.3 ha constituted of Tifton 85 in the city of Vista Gaucha - RS, Brazil, during the months from October to December in the year of 2012. The experimental area was georeferenced and divided into a sample mesh of 50 x 50 m, resulting in 16 sampling points. It was conducted two cuts on Tifton 85 to evaluate the dry mass production. Soil sampling was done in the layers from 0.00 - 0.10 m, 0.10 - 0.20 and 0.20 - 0.40 m. The data were submitted to descriptive statistical analysis and linear correlation matrix of Pearson, being the results specialized in thematic maps. The production of dry mass, nitrogen accumulation, phosphorus and potassium by Tifton 85 showed coefficients of variation ranked of high to very high, and in generally, demonstrated low correlation with the soil chemical properties, independently of the layer profile evaluated.

  13. 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.

  14. 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.

  15. Deciphering Noncovalent Interactions Accompanying 7,7,8,8-Tetracyanoquinodimethane Encapsulation within Biphene[n]arenes: Nucleus-Independent Chemical Shifts Approach.

    Science.gov (United States)

    Lande, Dipali N; Rao, Soniya S; Gejji, Shridhar P

    2016-07-18

    Binding of novel biphene[n]arene hosts to antiaromatic 7,7,8,8-tetracyanoquinodimethane (TCNQ) are investigated by DFT. Biphene[4]arene favors the inclusion complex through noncovalent interactions, such as hydrogen bonding, π-π stacking, C-H⋅⋅⋅π, and C-H⋅⋅⋅H-C dihydrogen bonding. Donor-acceptor complexation renders aromatic character to the guest through charge transfer. The formation of TCNQ anionic radicals through supramolecular π stacking significantly influences its chemical and photophysical behavior. Electron density reorganization consequent to encapsulation of TCNQ reflects in the shift of characteristic vibrations in the IR spectra. The accompanying aromaticities arising from the induced ring currents are analyzed by employing nucleus-independent chemical shifts based profiles. PMID:27028656

  16. 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.

  17. Measurement of sample temperatures under magic-angle spinning from the chemical shift and spin-lattice relaxation rate of 79Br in KBr powder

    OpenAIRE

    Thurber, Kent R.; Tycko, Robert

    2008-01-01

    Accurate determination of sample temperatures in solid state nuclear magnetic resonance (NMR) with magic-angle spinning (MAS) can be problematic, particularly because frictional heating and heating by radio-frequency irradiation can make the internal sample temperature significantly different from the temperature outside the MAS rotor. This paper demonstrates the use of 79Br chemical shifts and spin-lattice relaxation rates in KBr powder as temperature-dependent parameters for the determinati...

  18. Orientational constraints as three-dimensional structural constraints from chemical shift anisotropy: the polypeptide backbone of gramicidin A in a lipid bilayer.

    OpenAIRE

    Mai, W.; Hu, W; Wang, C; Cross, T A

    1993-01-01

    Chemical shifts observed from samples that are uniformly aligned with respect to the magnetic field can be used as very high-resolution structural constraints. This constraint takes the form of an orientational constraint rather than the more familiar distance constraint. The accuracy of these constraints is dependent upon the quality of the tensor characterization. Both tensor element magnitudes and tensor orientations with respect to the molecular frame need to be considered. Here these con...

  19. Correlation of the five test methods to assess chemical toxicity and relation to physical properties

    Energy Technology Data Exchange (ETDEWEB)

    Yoshioka, Y.; Ose, Y.; Sato, T.

    1986-08-01

    Biological tests using Orizias latipes (LC50 and oxygen uptake test), Moina macrocopa (LC50), and Dugesia japonica (head regeneration test and LC50) were carried out in order to clarify the mutual relationship of these test methods. The oxygen uptake rate of O. latipes was not effective to assess chemical toxicity. Adding the results of the growth inhibition test of Tetrahymena pyriformis (Yoshioka, Y., Ose, Y., and Sato, T. (1985). Sci. Total Environ. 43, 149-157), the correlation coefficients between each two test methods were calculated. The test results except EC50 and LC50 of D. japonica showed a good relation to each other. We determined the solubility and the n-octanol/water partition coefficient (P) of some chemicals used in the test. Log P interpreted the toxicity in mol/liter unit but not in mg/liter. Solubility was not a useful descripter neither in mol/liter nor in mg/liter unit.

  20. 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.

  1. 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.

  2. 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.

  3. Chemical Variation in Volatiles of Craniotome furcata: Correlation with Soil Properties

    Directory of Open Access Journals (Sweden)

    Shalini Singh

    2013-08-01

    Full Text Available The essential oils from the aerial parts of ten wild growing Craniotome furcata (Link. O. Kuntze of the family Lamiaceae collected from different locations in Uttarakhand, India, was analyzed by capillary GC and GC/MS. The oils were rich in sesquiterpenoids. The cluster analysis showed the presence of four groups. Group-I was significantly rich in δ-elemene and germacrene D while group-II had germacrene D in abundant quantity. α-Bisabolol oxide A, α-cadinol and germacrene D-4-ol were major constituents of group-III. Group-IV showed the presence of α-muurolol and germacrene D as major constituents. Germacrene D was found to be present in all the samples of C. furcata collected from different locations and was positively correlated with the altitude of the collection regions. Chemical variation in the volatiles was statistically correlated with altitude and soil properties.

  4. 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.

  5. 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

  6. 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.

  7. 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...

  8. Determination of the Optimal Energy Denominator Shift Parameter of KRb Electronic States in Quantum Chemical Computations Using Perturbation Theory

    Science.gov (United States)

    Shundalau, M. B.; Minko, A. A.

    2016-01-01

    The influence of the energy denominator shift (EDS) parameter and the quantitative and qualitative compositions of electronic states included in CASSCF(2,14)/XMCQDPT2 ab initio calculations of the ground state equilibrium internuclear distance and dissociation energy of polar KRb was determined.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. The HSP90 binding mode of a radicicol-like E-oxime from docking, binding free energy estimations, and NMR 15N chemical shifts

    Science.gov (United States)

    Spichty, Martin; Taly, Antoine; Hagn, Franz; Kessler, Horst; Barluenga, Sofia; Winssinger, Nicolas; Karplus, Martin

    2009-01-01

    We determine the binding mode of a macrocyclic radicicol-like oxime to yeast HSP90 by combining computer simulations and experimental measurements. We sample the macrocyclic scaffold of the unbound ligand by parallel tempering simulations and dock the most populated conformations to yeast HSP90. Docking poses are then evaluated by the use of binding free energy estimations with the linear interaction energy method. Comparison of QM/MM-calculated NMR chemical shifts with experimental shift data for a selective subset of back-bone 15N provides an additional evaluation criteria. As a last test we check the binding modes against available structure-activity-relationships. We find that the most likely binding mode of the oxime to yeast HSP90 is very similar to the known structure of the radicicol-HSP90 complex. PMID:19482409

  16. The correlation between selenium adsorption and the mineral and chemical composition of Taiwan local granite samples

    Energy Technology Data Exchange (ETDEWEB)

    Wang, TsingHai; Chiang, Chu-Ling; Wang, Chu-Fang [National Tsing Hua Univ., Hsinchu, Taiwan (China). Biomedical Engineering and Environmental Sciences

    2015-07-01

    Selenium-79 (Se-79) is a radioactive isotope of selenium, which is considered as one of the highly mobile nuclides since Se-79 would be presented in an anion species when dissolving into the intruded groundwater. Being an anionic species, the transport of Se-79 would be regulated by the metal oxides relevant minerals such as goethite and hematite (Jan et al., 2008). This is true that the transport of selenium in the shallow surface environment could be relatively easy to estimate by considering the amount of these metal oxides presenting in the soils and sediments. However, when dealing with deep geological repository, the transport of Se-79 becomes less predictable because of the much less content of metal oxide residing in the host rock such as granite. In order to conduct a reliable performance assessment of repository, it is very important to establish the correlation between selenium adsorption and the properties of potential host rock, in this study, the mineral and chemical compositions of Taiwan local granite. From this point of view, selenium adsorption experiments were conducted with 54 different Taiwan local granite samples collected from the depth ranging from 100 ∝ 400 meters below the surface. These granite samples represent a variety of deep geological environments, including the intact rock, groundwater intruded zones, and some weathered samples. Based upon our preliminary results, several solid conclusions could be made. First, the correlation coefficients between the Kd values and the mineral and chemical compositions are rather low (R-square values are often < 0.2). This points out the complexity of these geological samples and strongly suggests more efforts should be put into to acquire more relevant information. Second, the correlation between the selenium Kd values and the content of iron oxide (R-square 0.110) is much higher than that between the CEC of these granite samples (R-square 0.001). This clearly indicates that the minerals that

  17. 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

  18. 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.

  19. Geochemistry and stratigraphic correlation of basalt lavas beneath the Idaho Chemical Processing Plant, Idaho National Engineering Laboratory

    Science.gov (United States)

    Reed, M.F.; Bartholomay, R.C.; Hughes, S.S.

    1997-01-01

    Thirty-nine samples of basaltic core were collected from wells 121 and 123, located approximately 1.8 km apart north and south of the Idaho Chemical Processing Plant at the Idaho National Engineering Laboratory. Samples were collected from depths ranging from 15 to 221 m below land surface for the purpose of establishing stratigraphic correlations between these two wells. Elemental analyses indicate that the basalts consist of three principal chemical types. Two of these types are each represented by a single basalt flow in each well. The third chemical type is represented by many basalt flows and includes a broad range of chemical compositions that is distinguished from the other two types. Basalt flows within the third type were identified by hierarchical K-cluster analysis of 14 representative elements: Fe, Ca, K, Na, Sc, Co, La, Ce, Sm, Eu, Yb, Hf, Ta, and Th. Cluster analyses indicate correlations of basalt flows between wells 121 and 123 at depths of approximately 38-40 m, 125-128 m, 131-137 m, 149-158 m, and 183-198 m. Probable correlations also are indicated for at least seven other depth intervals. Basalt flows in several depth intervals do not correlate on the basis of chemical compositions, thus reflecting possible flow margins in the sequence between the wells. Multi-element chemical data provide a useful method for determining stratigraphic correlations of basalt in the upper 1-2 km of the eastern Snake River Plain.

  20. 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.

  1. 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.

  2. 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. PMID:25592734

  3. 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)

  4. 129Xe-NMR of xenon adsorbed on zeolites: determination of the dimensions of the void space from the chemical shift δ(129Xe)

    International Nuclear Information System (INIS)

    The chemical shift δS of xenon adsorbed on zeolite and extrapolated to zero concentration depends only on the internal void space of the solid. The smaller the channels or cavities, or the more restricted the diffusion, the greater δS becomes. We have calculated the theoretical values of the mean free path l-bar of xenon adsorbed in various zeolites. We deduce from them the dependence of the δS on l-bar. It is now possible to determine the dimensions of any void space in which xenon can be adsorbed. 4 refs.; 2 figs.; 3 tabs

  5. 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.

  6. Cross correlation of chemical profiles in minerals: insights into the architecture of magmatic reservoirs

    Science.gov (United States)

    Probst, Line; Caricchi, Luca; Gander, Martin; Wallace, Glenn

    2016-04-01

    Analysis of chemical zoning in minerals offers the opportunity to reconstruct the pre-eruptive conditions and the temporal evolution of magmatic reservoirs. The chemical composition of minerals is a function of the thermodynamic conditions of the reservoir from which they grow and therefore minerals record the evolution and variation of residual melt chemistry and intensive parameters within the magmatic system. A quantitative approach is required to determine if similar crystals actually shared a portion of their crystallisation history. These analyses are in many cases extremely time consuming and rather expensive. Therefore, it is not always possible to analyse a statically significant number of crystals, especially within their textural context in thin sections and that is the main reason to build automated methods. We are presenting a numerical cross-correlation method that compares the zonation pattern of minerals to identify if they share the totality or part of their growth history. We modified the method first developed by Wallace and Bergantz (2004) to compare profiles in minerals also from samples collected in different outcrops and that can be used for any dataset (i.e. geochemical proxies in stratigraphic sections). The main purpose of this method is to objectively compare chemical profiles in minerals (collected by electron microprobe, LA-ICP-MS or cathodoluminescence images) and quantify their degree of similarity. For this purpose, we use a well-known mathematical tool: the cross correlation which is a way of quantifying the difference between two given signals at a given position. Once our program was built, we performed tests using a set of synthetic profiles, profiles acquired along different transects of the same mineral and also on different minerals. Finally we applied our program to about 100 zircons from Kilgore Tuff, Heise Volcanic Field (USA) collected at different stratigraphic levels in two different outcrops. The correlation shows that

  7. 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 s...

  8. DFT Studies on Thermal Stabilities,Electronic Structures, and 13C Chemical Shifts of C24O2 Based on Fullerene C24(D6)

    Institute of Scientific and Technical Information of China (English)

    WANG Zhen; ZHANG Jing

    2011-01-01

    Quantum chemical calculations on some possible equilibrium geometries of C2402 isomers derived from C24 (D6) and C240 have been performed using density functional theory (DFT) method. The geometric and electronic structures as well as the relative energies and thermal stabilities of various C2402 isomers at the ground state have been calculated at the B3LYP/6-31G(d) level of theory. And the 1,4,2,5-C2402 isomer was found to be the most stable geometry where two oxygen atoms were added to the longest carbon-carbon bonds in the same pentagon from a thermodynamic point of view. Based on the optimized neutral geometries, the vertical ionization potential and vertical electron affinity have been obtained. Meanwhile, the vibrational frequencies,IR spectrum, and 13C chemical shifts of various C2402 isomers have been calculated and analyzed.

  9. 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).

  10. Unified Electrostatic Understanding on the Solvation-Induced Changes in the CN Stretching Frequency and the NMR Chemical Shifts of a Nitrile.

    Science.gov (United States)

    Torii, Hajime

    2016-09-15

    Understanding on the spectroscopic properties of a functional group is essential to use it to detect changes in the structural and/or dynamical properties through the situations of intermolecular interactions. The present study is devoted to elucidating the factors that control the solvation-induced changes in the C≡N stretching frequency and the (13)C and (15)N NMR chemical shifts of the nitrile group. It is shown that the nonelectrostatic contribution of the hydration-induced changes in the C≡N stretching frequency as previously thought, as well as the specific effect of hydrogen bonding on the (13)C and (15)N chemical shifts, actually originate from the spatially inhomogeneous nature of the electrostatic situation generated by the hydrogen-bond donating water molecule, especially by the OH bond dipole. On this basis, a unified electrostatic interaction model that encompasses the cases of both hydration and dipolar solvation is constructed. The responses of electrons in these two cases are also discussed. PMID:27547990

  11. 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.

  12. 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.)

  13. 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.

  14. Bioactive amines in Brazilian wines: types, levels and correlation with physico-chemical parameters

    Directory of Open Access Journals (Sweden)

    Solange C. Souza

    2005-01-01

    Full Text Available The levels of ten bioactive amines and the physico-chemical characteristics of Cabernet Sauvignon, Cabernet Franc and Merlot wines from Bento Gonçalves, RS, Brazil, vintage of 1999 were investigated. The physico-chemical characteristics varied significantly: pH from 3.80 to 4.07, total acidity from 67.7 to 85.3 meq/L, alcohol content from 11.45 to 12.46 mL/100 mL and total SO2 from 9.6 to 102 mg/L. Six amines were detected in every sample - spermidine, putrescine, histamine, tyramine, serotonine and phenylethylamine. Total amine levels ranged from 2.03 to 7.60 mg/L. Putrescine was the prevalent amine, contributing with 20 to 66% of total levels. The amine profile and total levels were affected to a greater extent by vinification practices compared to grape type. There was significant correlation between some amines and also between amines and the physico-chemical parameters. Histamine levels were well below limits recommended by several countries.Os teores de aminas bioativas e as características físico-químicas de Cabernet Sauvignon, Cabernet Franc e Merlot da região de Bento Gonçalves, RS, safra de 1999, foram analisados. As características físico-químicas variaram significativamente: pH de 3,80 a 4,07; acidez total de 67,7 a 85,3 meq/L, teor alcoólico de 11,45 a 12,46 mL/100 mL e SO2 total de 9,6 a 102 mg/L. Seis aminas estavam presentes em todas as amostras - espermidina, putrescina, histamina, tiramina, serotonina e feniletilamina. Os teores totais de aminas variaram de 2,03 a 7,60 mg/L. Putrescina foi a amina predominante, contribuindo com 20 a 66% do total. O perfil de aminas foi mais afetado pela vinícola do que pelo tipo de uva. Houve correlação significativa entre aminas e também entre aminas e parâmetros físico-químicos. Os teores de histamina detectados são inferiores aos limites máximos estipulados para o vinho em outros países.

  15. Insertion of CdSe quantum dots in ZnSe nanowires: Correlation of structural and chemical characterization with photoluminescence

    OpenAIRE

    Den Hertog, Martien; Elouneg-Jamroz, Miryam; Bellet-Amalric, Edith; Bounouar, Samir; Bougerol, Catherine; André, Régis; Genuist, Yann; Poizat, Jean-Philippe; Kheng, Kuntheak; Tatarenko, Serge

    2011-01-01

    ZnSe nanowires with CdSe quantum dot insertions were grown by molecular beam epitaxy using gold as a catalyst. Structural, chemical, and optical properties of the wires and quantum dots were characterized using electron microscopy and photoluminescence spectroscopy. We determined the crystalline structure, the chemical composition, and the size of the quantum dot and established a correlation between quantum dot size and luminescence. As expected, a blueshift of the luminescence was observed ...

  16. 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.

  17. Pronounced susceptibility to infection by Salmonella enterica serovar Typhimurium in mice chronically exposed to lead correlates with a shift to Th2-type immune responses

    International Nuclear Information System (INIS)

    Persistent exposure to inorganic lead (Pb) is known to adversely affect the immune system. In the present study, we assessed the effect of chronic Pb exposure on susceptibility to infection by the facultative intracellular pathogen Salmonella enterica serovar Typhimurium. Mice were exposed to 10 mM Pb-acetate in drinking water for ∼ 16 weeks, resulting in a significant level of Pb in the blood (106.2 ± 8.9 μg/dl). Pb exposure rendered mice susceptible to Salmonella infection, manifested by increased bacterial burden in target organs and heightened mortality. Flow cytometric analysis of the splenic cellular composition in normal and Pb-exposed mice revealed no gross alteration in the ratios of B and T lymphocytes or myeloid cells. Similarly, the capacity of B and T cells to upregulate the expression of activation antigens in response to mitogenic or inflammatory stimuli was not hindered by Pb exposure. Analysis of the ability of ex vivo-cultured splenocytes to secrete cytokines demonstrated a marked reduction in IFN-γ and IL-12p40 production associated with Pb exposure. In contrast, secretion of IL-4 by splenocytes of Pb-treated mice was 3- to 3.6-fold higher than in normal mice. The increased capacity to produce IL-4 correlated with a shift in the in vivo anti-Salmonella antibody response from the protective IgG2a isotype to the Th2-induced IgG1 isotype. We conclude that chronic exposure to high levels of Pb results in a state of immunodeficiency which is not due to an overt cytotoxic or immunosuppressive mechanism, but rather is largely caused by a shift in immune responsiveness to Th2-type reactions

  18. 1H chemical shift imaging of the brain in guanidino methyltransferase deficiency, a creatine deficiency syndrome; guanidinoacetate accumulation in the gray matter

    International Nuclear Information System (INIS)

    MR spectroscopy results in a mild case of guanidinoacetate methyltransferase (GAMT) deficiency are presented. The approach differs from previous MRS studies in the acquisition of a chemical shift imaging spectral map showing gray and white matter with the corresponding spectra in one overview. MR spectroscopy revealed guanidinoacetate (GAA) in the absence of creatine. New is that GAA signals are more prominent in gray matter than in white. In the prevailing view, that enzyme deficiency is localized in liver and pancreas and that all GAA is transported into the brain from the blood and the cerebrospinal fluid, this would be compatible with a more limited uptake and/or better clearance of GAA from the white matter compared to the grey matter. (orig.)

  19. 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.

  20. 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.

  1. 31P-MR spectroscopy of all regions of the human heart at 1.5 T with acquisition-weighted chemical shift imaging

    International Nuclear Information System (INIS)

    Aim: Aim of this study was to show whether or not acquisition-weighted chemical shift imaging (AW-CSI) allows the determination of PCr and ATP in the lateral and posterior wall of the human heart at 1.5 T. Methods: 12 healthy volunteers were examined using a conventional chemical shift imaging (CSI) and an AW-CSI. The sequences differed only in the number of repetitions for each point in k space. A hanning function was used as filter function leading to 7 repetitions in the center of the k space and 0 in the corners. Thus, AW-CSI had the same resolution as the CSI sequence. The results for both sequences were analyzed using identically positioned voxels in the septal, anterior, lateral and posterior wall. Results: The determined averaged AW-CSI signal to noise ratios were higher for PCr by a factor of 1.3 and for ATP by 1.4 than those of CSI. The PCr/ATP ratios were higher by a factor of 1.2 - 1.3 and showed a smaller standard deviation in all locations for AW-CSI. The mean PCr/ATP ratios determined by AW-CSI of septal, lateral and posterior wall were almost identical (1.72 - 1.76), while it was higher in the anterior wall (1.9). Conclusions: The reduced contamination in AW-CSI improves the signal to noise ratio and the determination of the PCr/ATP ratio in cardiac 31P spectroscopy compared to CSI with the same resolution. The results in volunteers indicate that AW-CSI renders 31P spectroscopy of the lateral and posterior wall of the human heart feasible for patient studies at 1.5 T. (orig.)

  2. 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.

  3. 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

  4. 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.

  5. 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 t...... interaction between exchange coupled rings leads to antiparallel vortex states and extended onion states. (c) 2008 American Institute of Physics....

  6. Correlated analysis of chemical variations with spectroscopic features of the K-Na jarosite solid solutions relevant to Mars

    Science.gov (United States)

    Ling, Zongcheng; Cao, Fengke; Ni, Yuheng; Wu, Zhongchen; Zhang, Jiang; Li, Bo

    2016-06-01

    Detailed chemical, structural and spectroscopic properties of jarosite solid solution minerals are key information for their potential discoveries by future remote sensing and in-situ detections on Mars. We successfully synthesized seven homogeneous K-Na jarosite solid solutions under hydrothermal conditions at 140 °C, whose phase identifications and chemical compositions are confirmed by X-ray diffraction (XRD) and inductively coupled plasma mass spectrometry (ICP-MS). The chemical ratios of K/(K+Na) in jarosite solid solutions lead to systematic shifts of their characteristic Raman peaks ν1 (SO4)2- (from 1006 to 1011.3 cm-1), ν3 (SO4)2- (from 1100.6 to 1111.2 cm-1), ν2 (SO4)2- (from 434.2 to 444.8 cm-1) with the increase of Na content. While the OH stretching mode decreases with even larger peak position variations (e.g., ∼3410 cm-1 peak shifts from 3410.5 to 3385.7 cm-1) as the K-Na jarosite solid solutions are enriched in Na content. Raman spectroscopic measurements of the seven K-Na jarosite solid solutions enabled us to build a calibration that uses Raman peak positions to estimate K-Na variation in jarosite, which is the key step for their possible applications in the future Raman applications on Mars' missions (e.g., ExoMars and Mars 2020 missions). The band assignments and compositional related variations of their XRD, near-infrared (NIR) and mid-infrared (MIR) spectra also provide informative clues for identifying the jarosite minerals and inferring their composition during martian in-situ and remote sensing measurements.

  7. High resolution spectroscopy and chemical shift imaging of hyperpolarized 129Xe dissolved in the human brain in vivo at 1.5 tesla

    Science.gov (United States)

    Rao, Madhwesha; Stewart, Neil J.; Norquay, Graham; Griffiths, Paul D.

    2016-01-01

    Purpose Upon inhalation, xenon diffuses into the bloodstream and is transported to the brain, where it dissolves in various compartments of the brain. Although up to five chemically distinct peaks have been previously observed in 129Xe rat head spectra, to date only three peaks have been reported in the human head. This study demonstrates high resolution spectroscopy and chemical shift imaging (CSI) of 129Xe dissolved in the human head at 1.5 Tesla. Methods A 129Xe radiofrequency coil was built in‐house and 129Xe gas was polarized using spin‐exchange optical pumping. Following the inhalation of 129Xe gas, NMR spectroscopy was performed with spectral resolution of 0.033 ppm. Two‐dimensional CSI in all three anatomical planes was performed with spectral resolution of 2.1 ppm and voxel size 20 mm × 20 mm. Results Spectra of hyperpolarized 129Xe dissolved in the human head showed five distinct peaks at 188 ppm, 192 ppm, 196 ppm, 200 ppm, and 217 ppm. Assignment of these peaks was consistent with earlier studies. Conclusion High resolution spectroscopy and CSI of hyperpolarized 129Xe dissolved in the human head has been demonstrated. For the first time, five distinct NMR peaks have been observed in 129Xe spectra from the human head in vivo. Magn Reson Med 75:2227–2234, 2016. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. PMID:27080441

  8. 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.

  9. 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.

  10. 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.

  11. 13C Magic angle spinning NMR analysis and quantum chemical modeling of the bathochromic shift of astaxanthin in alpha-crustacyanin, the blue carotenoprotein complex in the carapace of the lobster Homarus gammarus.

    Science.gov (United States)

    Weesie, R J; Jansen, F J; Merlin, J C; Lugtenburg, J; Britton, G; de Groot, H J

    1997-06-17

    Selective isotope enrichment, 13C magic angle spinning (MAS) NMR, and semiempirical quantum chemical modeling, have been used to analyze ligand-protein interactions associated with the bathochromic shift of astaxanthin in alpha-crustacyanin, the blue carotenoprotein complex from the carapace of the lobster Homarus gammarus. Spectra of alpha-crustacyanin were obtained after reconstitution with astaxanthins labeled with 13C at positions 4,4', 12,12', 13,13', or 20,20'. The data reveal substantial downfield shifts of 4.9 and 7.0 ppm at positions 12 and 12' in the complex, respectively. In contrast, at the 13 and 13' positions, small upfield shifts of 1.9 ppm were observed upon binding to the protein. These data are in line with previously obtained results for positions 14,14' (3.9 and 6.8 ppm downfield) and 15,15' (0.6 ppm upfield) and confirm the unequal perturbation of both halves after binding of the chromophore. However, these results also show that the main perturbation is of symmetrical origin, since the chemical shift differences exhibit a similar pattern in both halves of the astaxanthin molecule. A small downfield shift of 2.4 ppm was detected for the 4 and 4' positions. Finally, the 20,20' methyl groups are shifted 0.4 ppm upfield by the protein. The full data set provides convincing evidence that charge polarization is of importance for the bathochromic shift. The NMR shifts are compared with calculated charge densities for astaxanthin subjected to variations in protonation states of the ring-functional groups, as models of ligand-protein interactions. Taking into account the color shift and other available optical data, the current model for the mechanisms of interaction with the protein was refined. The results point toward a mechanism in which the astaxanthin is charged and subject to strong electrostatic polarizations originating from both keto groups, most likely a double protonation. PMID:9200677

  12. 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. PMID:26845204

  13. Measurement of sample temperatures under magic-angle spinning from the chemical shift and spin-lattice relaxation rate of 79Br in KBr powder

    Science.gov (United States)

    Thurber, Kent R.; Tycko, Robert

    2009-01-01

    Accurate determination of sample temperatures in solid state nuclear magnetic resonance (NMR) with magic-angle spinning (MAS) can be problematic, particularly because frictional heating and heating by radio-frequency irradiation can make the internal sample temperature significantly different from the temperature outside the MAS rotor. This paper demonstrates the use of 79Br chemical shifts and spin-lattice relaxation rates in KBr powder as temperature-dependent parameters for the determination of internal sample temperatures. Advantages of this method include high signal-to-noise, proximity of the 79Br NMR frequency to that of 13C, applicability from 20 K to 320 K or higher, and simultaneity with adjustment of the MAS axis direction. We show that spin-lattice relaxation in KBr is driven by a quadrupolar mechanism. We demonstrate a simple approach to including KBr powder in hydrated samples, such as biological membrane samples, hydrated amyloid fibrils, and hydrated microcrystalline proteins, that allows direct assessment of the effects of frictional and radio-frequency heating under experimentally relevant conditions. PMID:18930418

  14. Comprehensive signal assignment of 13C-labeled lignocellulose using multidimensional solution NMR and 13C chemical shift comparison with solid-state NMR.

    Science.gov (United States)

    Komatsu, Takanori; Kikuchi, Jun

    2013-09-17

    A multidimensional solution NMR method has been developed using various pulse programs including HCCH-COSY and (13)C-HSQC-NOESY for the structural characterization of commercially available (13)C labeled lignocellulose from potatoes (Solanum tuberosum L.), chicory (Cichorium intybus), and corn (Zea mays). This new method allowed for 119 of the signals in the (13)C-HSQC spectrum of lignocelluloses to be assigned and was successfully used to characterize the structures of lignocellulose samples from three plants in terms of their xylan and xyloglucan structures, which are the major hemicelluloses in angiosperm. Furthermore, this new method provided greater insight into fine structures of lignin by providing a high resolution to the aromatic signals of the β-aryl ether and resinol moieties, as well as the diastereomeric signals of the β-aryl ether. Finally, the (13)C chemical shifts assigned in this study were compared with those from solid-state NMR and indicated the presence of heterogeneous dynamics in the polysaccharides where rigid cellulose and mobile hemicelluloses moieties existed together. PMID:24010724

  15. 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

  16. 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.

  17. Determination of NH proton chemical shift anisotropy with 14N-1H heteronuclear decoupling using ultrafast magic angle spinning solid-state NMR

    Science.gov (United States)

    Pandey, Manoj Kumar; Nishiyama, Yusuke

    2015-12-01

    The extraction of chemical shift anisotropy (CSA) tensors of protons either directly bonded to 14N nuclei (I = 1) or lying in their vicinity using rotor-synchronous recoupling pulse sequence is always fraught with difficulty due to simultaneous recoupling of 14N-1H heteronuclear dipolar couplings and the lack of methods to efficiently decouple these interactions. This difficulty mainly arises from the presence of large 14N quadrupolar interactions in comparison to the rf field that can practically be achieved. In the present work it is demonstrated that the application of on-resonance 14N-1H decoupling with rf field strength ∼30 times weaker than the 14N quadrupolar coupling during 1H CSA recoupling under ultrafast MAS (90 kHz) results in CSA lineshapes that are free from any distortions from recoupled 14N-1H interactions. With the use of extensive numerical simulations we have shown the applicability of our proposed method on a naturally abundant L-Histidine HCl·H2O sample.

  18. 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.

  19. Bioactive amines in Brazilian wines: types, levels and correlation with physico-chemical parameters

    OpenAIRE

    Solange C. Souza; Karine H. Theodoro; Élson R. Souza; Silvana da Motta; Maria Beatriz Abreu Glória

    2005-01-01

    The levels of ten bioactive amines and the physico-chemical characteristics of Cabernet Sauvignon, Cabernet Franc and Merlot wines from Bento Gonçalves, RS, Brazil, vintage of 1999 were investigated. The physico-chemical characteristics varied significantly: pH from 3.80 to 4.07, total acidity from 67.7 to 85.3 meq/L, alcohol content from 11.45 to 12.46 mL/100 mL and total SO2 from 9.6 to 102 mg/L. Six amines were detected in every sample - spermidine, putrescine, histamine, tyramine, seroton...

  20. 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…

  1. 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.

  2. 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...

  3. 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.

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

    Science.gov (United States)

    Micarelli, Alessandro; Viziano, Andrea; Genovesi, Giuseppe; Bruno, Ernesto; Ottaviani, Fabrizio; Alessandrini, Marco

    2016-01-01

    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. PMID:27157687

  5. 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.

  6. 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.

  7. Effects of correlated parameters and uncertainty in electronic-structure-based chemical kinetic modelling

    Science.gov (United States)

    Sutton, Jonathan E.; Guo, Wei; Katsoulakis, Markos A.; Vlachos, Dionisios G.

    2016-04-01

    Kinetic models based on first principles are becoming common place in heterogeneous catalysis because of their ability to interpret experimental data, identify the rate-controlling step, guide experiments and predict novel materials. To overcome the tremendous computational cost of estimating parameters of complex networks on metal catalysts, approximate quantum mechanical calculations are employed that render models potentially inaccurate. Here, by introducing correlative global sensitivity analysis and uncertainty quantification, we show that neglecting correlations in the energies of species and reactions can lead to an incorrect identification of influential parameters and key reaction intermediates and reactions. We rationalize why models often underpredict reaction rates and show that, despite the uncertainty being large, the method can, in conjunction with experimental data, identify influential missing reaction pathways and provide insights into the catalyst active site and the kinetic reliability of a model. The method is demonstrated in ethanol steam reforming for hydrogen production for fuel cells.

  8. 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.

  9. Correlation between chemical composition of dental calculus and bone samples in ancient human burials: perspectives in paleonutritional studies

    International Nuclear Information System (INIS)

    Full text: The authors describe the results of an assay based on the comparison between chemical composition of dental calculus and bone respectively obtained from teeth and bones of ancient skeletons. The chemical analysis has been performed by synchrotron light. The concentrations of the following oligoelements having paleonutritional correlations were analysed: Fe, Cu, Zn, Pb, Sr and Ca. The authors demonstrate that- in a given individual the concentration of such elements in the bone sample were in the range of those obtained for the same elements in the sample of dental calculus. Such correspondence suggests that the chemical analysis of dental calculus may give paleonutritional indications analogous to those deriving from the analysis of bone samples. The authors underline also that the use of dental calculus has a distinct advantage over the use of bone samples, since it may allow a diachronic investigation. In fact, dental calculus typically presents a concentric pattern of growth, and the chemical composition of each layer may vary in accordance with temporal dietary variations. This is not the case for bone. This fact is the theoretical basis for the possible future development of techniques directed to the reconstruction of variations in the dietary habits of ancient individuals, possibly in relation to environmental seasonal changes

  10. Overall structure and sugar dynamics of a DNA dodecamer from homo- and heteronuclear dipolar couplings and 31P chemical shift anisotropy

    International Nuclear Information System (INIS)

    The solution structure of d(CGCGAATTCGCG)2 has been determined on the basis of an exceptionally large set of residual dipolar couplings. In addition to the heteronuclear 13C-1H and 15N-1H and qualitative homonuclear 1H-1H dipolar couplings, previously measured in bicelle medium, more than 300 quantitative 1H-1H and 22 31P-1H dipolar restraints were obtained in liquid crystalline Pf1 medium, and 22 31P chemical shift anisotropy restraints. High quality DNA structures can be obtained solely on the basis of these new restraints, and these structures are in close agreement with those calculated previously on the basis of 13C-1H and 15N-1H dipolar couplings. In the newly calculated structures, 31P-1H dipolar and 3JsubH3'Psub couplings and 31P CSA data restrain the phosphodiester backbone torsion angles. The final structure represents a quite regular B-form helix with a modest bending of ∼10 deg., which is essentially independent of whether or not electrostatic terms are used in the calculation. Combined, the number of homo- and heteronuclear dipolar couplings significantly exceeds the number of degrees of freedom in the system. Results indicate that the dipolar coupling data cannot be fit by a single structure, but are compatible with the presence of rapid equilibria between C2'-endo and C3'-endo deoxyribose puckers (sugar switching). The C2'-H2'/H2'' dipolar couplings in B-form DNA are particularly sensitive to sugar pucker and yield the largest discrepancies when fit to a single structure. To resolve these discrepancies, we suggest a simplified dipolar coupling analysis that yields N/S equilibria for the ribose sugar puckers, which are in good agreement with previous analyses of NMR JHH couplings, with a population of the minor C3'-endo form higher for pyrimidines than for purines

  11. 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.

  12. Chemical Fluxes in Cellular Steady States Measured by Fluorescence Correlation Spectroscopy

    Science.gov (United States)

    Qian, Hong; Elson, Elliot L.

    Genetically, identical cells adopt phenotypes that have different structures, functions, and metabolic properties. In multi-cellular organisms, for example, tissue-specific phenotypes distinguish muscle cells, liver cells, fibroblasts, and blood cells that differ in biochemical functions, geometric forms, and interactions with extracellular environments. Tissue-specific cells usually have different metabolic functions such as synthesis of distinct spectra of secreted proteins, e.g., by liver or pancreatic cells, or of structural proteins, e.g., muscle vs. epithelial cells. But more importantly, a phenotype should include a dynamic aspect: different phenotypes can have distinctly different dynamic functions such as contraction of muscle cells and locomotion of leukocytes. The phenotypes of differentiated tissue cells are typically stable, but they can respond to changes in external conditions, e.g., as in the hypertrophy of muscle cells in response to extra load [1] or the phenotypic shift of fibroblasts to myofibroblasts as part of the wound healing response [2]. Cells pass through sequences of phenotypes during development and also undergo malignant phenotypic transformations as occur in cancer and heart disease.

  13. 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.

  14. Correlation of chromosome patterns in human leukemic cells with exposure to chemicals and/or radiation

    International Nuclear Information System (INIS)

    This project seeks to defining the chromosome segments associated with radiation induced leukemogenesis (treatment-related acute myeloid leukemia, or t-AML). Towards these goals genetic analysis of human chromosomes 5 and 7 continues to investigate correlation of treatment with balanced and unbalanced chromosomal translocations. Progress is being made in cloning the breakpoints in balanced translocations in t-AML, that is to clone the t(9;11) and t(11;19) breakpoints, to clone the t(3;21)(q26;q22) breakpoints and to determine the relationship of these translocations to prior exposure to topoisomerase II inhibitors. 11 figs. 3 figs

  15. 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).

  16. 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

  17. Correlating chemical sensitivity and basal gene expression reveals mechanism of action

    Science.gov (United States)

    Rees, Matthew G.; Seashore-Ludlow, Brinton; Cheah, Jaime H.; Adams, Drew J.; Price, Edmund V.; Gill, Shubhroz; Javaid, Sarah; Coletti, Matthew E.; Jones, Victor L.; Bodycombe, Nicole E.; Soule, Christian K.; Alexander, Benjamin; Li, Ava; Montgomery, Philip; Kotz, Joanne D.; Hon, C. Suk-Yee; Munoz, Benito; Liefeld, Ted; Dančík, Vlado; Haber, Daniel A.; Clish, Clary B.; Bittker, Joshua A.; Palmer, Michelle; Wagner, Bridget K.; Clemons, Paul A.; Shamji, Alykhan F.; Schreiber, Stuart L.

    2015-01-01

    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. To test this idea, we correlated the sensitivity patterns of 481 compounds with ~19,000 basal transcript levels across 823 different human cancer cell lines and identified selective outlier transcripts. This process yielded many novel mechanistic insights, including the identification of activation mechanisms, cellular transporters, and direct protein targets. We found that ML239, originally identified in a phenotypic screen for selective cytotoxicity in breast cancer stem-like cells, most likely acts through activation of fatty acid desaturase 2 (FADS2). These data and analytical tools are available to the research community through the Cancer Therapeutics Response Portal. PMID:26656090

  18. Impact of environmental chemicals on key transcription regulators and correlation to toxicity end points within EPA's ToxCast program.

    Science.gov (United States)

    Martin, Matthew T; Dix, David J; Judson, Richard S; Kavlock, Robert J; Reif, David M; Richard, Ann M; Rotroff, Daniel M; Romanov, Sergei; Medvedev, Alexander; Poltoratskaya, Natalia; Gambarian, Maria; Moeser, Matt; Makarov, Sergei S; Houck, Keith A

    2010-03-15

    Exposure to environmental chemicals adds to the burden of disease in humans and wildlife to a degree that is difficult to estimate and, thus, mitigate. The ability to assess the impact of existing chemicals for which little to no toxicity data are available or to foresee such effects during early stages of chemical development and use, and before potential exposure occurs, is a pressing need. However, the capacity of the current toxicity evaluation approaches to meet this demand is limited by low throughput and high costs. In the context of EPA's ToxCast project, we have evaluated a novel cellular biosensor system (Factorial (1) ) that enables rapid, high-content assessment of a compound's impact on gene regulatory networks. The Factorial biosensors combined libraries of cis- and trans-regulated transcription factor reporter constructs with a highly homogeneous method of detection enabling simultaneous evaluation of multiplexed transcription factor activities. Here, we demonstrate the application of the technology toward determining bioactivity profiles by quantitatively evaluating the effects of 309 environmental chemicals on 25 nuclear receptors and 48 transcription factor response elements. We demonstrate coherent transcription factor activity across nuclear receptors and their response elements and that Nrf2 activity, a marker of oxidative stress, is highly correlated to the overall promiscuity of a chemical. Additionally, as part of the ToxCast program, we identify molecular targets that associate with in vivo end points and represent modes of action that can serve as potential toxicity pathway biomarkers and inputs for predictive modeling of in vivo toxicity. PMID:20143881

  19. Correlation of chromosome patterns in human leukemic cells with exposure to chemicals and/or radiation

    International Nuclear Information System (INIS)

    This document lists the major accomplishments funded by DOE in the period of January 1989 through June 1991. Specific topics covered include: studies of chromosome translocations in patients with Acute Myeloid Leukemia (AML) de novo; correlation of karyotype and therapeutic response; the relationship of specific chromosomal abnormalities to a patient's occupational history; definition of regions on chromosome 5 involved in leukemogenesis; the influence of pervious chemotherapy on leukemogenesis; identification of genes at or near breakpoints involved in leukemia and lymphoma; identification of the critical rearrangement in the 9;11 translocation; molecular analysis of translocations involving 11q23; identification of other genes (like RAS) involved in leukemogenesis; development of fluorescence in situ hybridization as a cytogenetic tool; and examination of an unequivocal case of radiation induced preleukemia. 26 refs., 8 figs., 6 tabs

  20. 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.

  1. 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.

  2. Structural and spectroscopic evidence for stable chemical bonds and the correlation with high Tc superconductivity

    International Nuclear Information System (INIS)

    It is discovered that in the high-Tc superconducting YBa2−xLaxCu3Oz system, by structural analysis and Raman spectroscopy, a stable ‘fixed triangle’ structure exists in the CuO2 planes. All chemical bonds and angles constituting the O(3)–Cu(2)–O(2) triangle are almost constant with doping. The frequencies and linewidths of the out-of-phase c-axis O(2)–O(3) buckling modes around 337 cm−1 and the in-plane Cu(2)–O(2) bond stretching modes around 534 cm−1 are both independent of the doping level, providing direct evidence for the stability of this fixed triangle. It was previously revealed that just these two phonons couple strongly with the antinodal and nodal electronic states, respectively, resulting in an anisotropic electron–phonon interaction in the cuprates. This work implies that the stability of the CuO2 subunit and phonons related to it might be quite important in inducing the d-wave high-Tc superconductivity and should be paid more attention. (paper)

  3. 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.

  4. Experimental measurement of local displacement and chemical pair correlations in crystalline solid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Sparks, C.L.; Ice, G.E.; Robertson, J.L. [Oak Ridge National Lab., TN (United States); Shaffer, L.B. [Anderson Univ., Anderson, IN (United States)

    1993-10-01

    Measurement of near-neighbor atomic arrangements in crystalline solid solutions is well established and provides meaningful values for chemical preference of atoms for their near neighbors to beyond the first ten neighboring shells. Static displacements (atomic size) between these atom pairs have mostly been either ignored in the recovery of the local pair preferences or removed by making use of the displacement scattering dependence on momentum transfer. With intense and energy tunable x-ray synchrotron sources, our ability to recover these static displacements between atoms has greatly improved. Data taken with multiple x-ray energies to obtain the contrast necessary to separate like from unlike neighbor pair distances are discussed for the two cases studied to date: A locally ordered Ni{sub 77.5}Fe{sub 22.5} crystal and a locally clustered Fe{sub 53}Cr{sub 47} crystal. Analysis of experimental parameters and data gives the systematic and statistical errors on the recovered parameters. Meaningful atomic displacements from the mean lattice can be measured and recovered. These displacements help us understand material properties and will provide theorists with tests for their calculations.

  5. 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.

  6. Tough Shift

    DEFF Research Database (Denmark)

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

    2015-01-01

    people to change their behavior at home. Leveraging prior research on encouraging reductions in residential energy use through game play, we introduce ShareBuddy: a casual mobile game intended to encourage players not only to reduce, but also to shift their electricity use. We conducted two field studies...... real-world resource use into a game....

  7. 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.

  8. 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

  9. Oxygen 17 NMR in the evaluation of oxygen bounding with central ion using hydrolysis products of niobium, tantalum, arsenic, antimony pentafluorides as an example. Symbasis in the change of 17O and 19F chemical shifts

    International Nuclear Information System (INIS)

    Hydrolysis products of niobium, tantalum, antimony and arsenic pentafluorides in acetonitrile solution were studied by the methods of 17O and 19F NMR. In 17O NMR spectra of niobium and tantalum pentafluorides hydrolysis products resonance signals of oxo-, hydroxo- and aquafluorocomplexes were defined. Considerable shift of 17O NMR resonance signals towards weak field making up about 300 m.p., may indicate a higher covalency (Π-character) of Nb-O bond compared to Ta-O one. Symbasis in the change of chemical shifts in 17O NMR and 19F NMR of the relevant hexafluorides and hydrolysis products was detected implying similarity of chemical bond nature in oxygen and fluorine

  10. Proton-detected 3D 14N/14N/1H isotropic shift correlation experiment mediated through 1H-1H RFDR mixing on a natural abundant sample under ultrafast MAS

    Science.gov (United States)

    Pandey, Manoj Kumar; Nishiyama, Yusuke

    2015-09-01

    In this contribution, we have demonstrated a proton detection-based approach on a natural abundant powdered L-Histidine HCl-H2O sample at ultrafast magic angle spinning (MAS) to accomplish 14N/14N correlation from a 3D 14N/14N/1H isotropic shift correlation experiment mediated through 1H finite-pulse radio frequency-driven recoupling (fp-RFDR). Herein the heteronuclear magnetization transfer between 14N and 1H has been achieved by HMQC experiment, whereas 14N/14N correlation is attained through enhanced 1H-1H spin diffusion process due to 1H-1H dipolar recoupling during the RFDR mixing. While the use of ultrafast MAS (90 kHz) provides sensitivity enhancement through increased 1H transverse relaxation time (T2), the use of micro-coil probe which can withstand strong 14N radio frequency (RF) fields further improves the sensitivity per unit sample volume.

  11. Electronic Structures of the [Fe(N2)(SiP(iPr)3)](+1/0/-1) Electron Transfer Series: A Counterintuitive Correlation between Isomer Shifts and Oxidation States.

    Science.gov (United States)

    Ye, Shengfa; Bill, Eckhard; Neese, Frank

    2016-04-01

    The electronic structure analysis of the low-spin iron(II/I/0) complexes [Fe(N2)(SiP(iPr)3)](+/0/-) (SiP(iPr)3 = [Si(o-C6H4P(i)Pr2)3](-)) recently published by J. Peters et al. (Nature Chem. 2010, 2, 558-565) reveals that the redox processes stringing this electron transfer series are best viewed as metal-centered reductions, i.e. Fe(II)N2(0) → Fe(I)N2(0) → Fe(0)N2(0). Superficially, the interpretation seems to be incompatible with the Mössbauer measurement, because the observed isomer shifts are more negative for the lower oxidation states, whereas typically iron-based reduction tends to increase the isomer shift. To rationalize the experimental findings, we analyzed the contributions from the 1s to 4s orbitals to the charge density at the Mössbauer nucleus and found that the positive correlation between the isomer shift and the oxidation state results from an unusual shrinking of the Fe-N2 bond upon reduction due to enhanced N2 to Fe π-backbonding. The other effects of reduction arising from shielding of the nuclear potential, decreasing covalency, and changes in the 4s population would induce the usual negative correlation. The structure distortion dictates the radial distribution of the 4s orbital and the charge density at the nucleus such that a virtually linear relationship between the isomer shift and the Fe-N2 distance could be identified for this series. PMID:26966915

  12. 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.

  13. 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.

  14. 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

  15. Shifting densities

    OpenAIRE

    Mille, Matthieu

    2000-01-01

    In this paper, the author adopt a time-geography approach to examine the temporal variation of urban density by analysing spatial load changes at different times of the day at the communal and community level. The evolution of means of transport coupled with the abandon of the notion of direct proximity to the urban dwelling place provide the basis for this new approach to the study of urban densities. The shift towards spatial specialisation within cities has lead to radical changes in the f...

  16. The strong diachronous Muschelkalk/Keuper facies shift in the Central European Basin: implications from the type-section of the Erfurt Formation (Lower Keuper, Triassic) and basin-wide correlations

    Science.gov (United States)

    Franz, Matthias; Henniger, Matthias; Barnasch, Jens

    2013-04-01

    The transition from the shallow marine Upper Muschelkalk Sea to the Lower Keuper fluvial plain represents the most diachronous facies shift of the entire Germanic Triassic. The type-section of the fluvial Lower Keuper (Erfurt Formation) is described in detail for the first time including biostratigraphic dating of the Muschelkalk/Keuper boundary. The type-section is integrated into a NNE-SSW cross section through the Central European Basin, and the Muschelkalk/Keuper facies shift is constrained by high-resolution conodont and ceratite biostratigraphy. Thus, the fundamental changes in palaeogeography, shifts of facies belts and stratal pattern architecture are visualised. Forced by a rapid transgression from Tethyan waters, the shallow marine Upper Muschelkalk Sea attained its maximum flooding in the lower conodont zone 2 ( sequens/pulcher to philippi/robustus zones). Subsequent slow continuous regression to the South was accompanied by step-by-step progradation of coastal to fluvial plain environments of the Lower Keuper, culminating in a fluvial plain extending to South Germany. Based on stratal patterns, an improved sequence-stratigraphic interpretation for the Upper Muschelkalk/Lower Keuper interval is suggested. In combination with biostratigraphic arguments, the new sequence-stratigraphy points to a revised correlation of this interval within the Tethyan Triassic, incorporating the positions of the Anisian/Ladinian and Fassanian/Longobardian boundaries.

  17. On the calculation of Mössbauer isomer shift.

    Science.gov (United States)

    Filatov, Michael

    2007-08-28

    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 nucleus model in the calculations enables one to incorporate straightforwardly the effects of relativity and electron correlation. The results of benchmark calculations carried out for several iron complexes as well as for a number of atoms and atomic ions are presented and compared with the available experimental and theoretical data. PMID:17764223

  18. Absorption driven focus shift

    Science.gov (United States)

    Harrop, N.; Wolf, S.; Maerten, O.; Dudek, K.; Ballach, S.; Kramer, R.

    2016-03-01

    Modern high brilliance near infrared lasers have seen a tremendous growth in applications throughout the world. Increased productivity has been achieved by higher laser power and increased brilliance of lasers. Positive impacts on the performance and costs of parts are opposed to threats on process stability and quality, namely shift of focus position over time. A high initial process quality will be reduced by contamination of optics, eventually leading to a focus shift or even destruction of the optics. Focus analysis at full power of multi-kilowatt high brilliance lasers is a very demanding task because of high power densities in the spot and the high power load on optical elements. With the newly developed high power projection optics, the High-Power Micro-Spot Monitor High Brilliance (HP-MSM-HB) is able to measure focus diameter as low as 20 μm at power levels up to 10 kW at very low internal focus shift. A main driving factor behind thermally induced focus shift is the absorption level of the optical element. A newly developed measuring system is designed to determine the relative absorption level in reference to a gold standard. Test results presented show a direct correlation between absorption levels and focus shift. The ability to determine the absorption level of optical elements as well as their performance at full processing power before they are put to use, enables a high level of quality assurance for optics manufacturers and processing head manufacturers alike.

  19. 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.

  20. Acquired cisplatin resistance in human ovarian A2780 cancer cells correlates with shift in taurine homeostasis and ability to volume regulate

    DEFF Research Database (Denmark)

    Sørensen, Belinda Halling; Thorsteinsdottir, Unnur Arna; Lambert, Ian Henry

    2014-01-01

    Cisplatin resistance is a major challenge in the treatment of cancer and develops through reduced drug accumulation and an increased ability to avoid drug-induced cell damage, cell shrinkage, and hence initiation of apoptosis. Uptake and release of the semiessential amino acid taurine contribute to...... cell volume homeostasis, and taurine has been reported to have antiapoptotic effects. Here we find that volume-sensitive taurine release in cisplatin-sensitive [wild-type (WT)] human ovarian cancer A2780 cells is reduced in the presence of the phospholipase A2 inhibitor bromenol lactone, the 5......-induced cell death in RES A2780 cells correlates with an increased accumulation of taurine, due to an increased taurine uptake and a concomitant impairment of the volume-sensitive taurine release pathway, as well an inability to reduce cell volume after osmotic cell swelling. Downregulation of volume...

  1. 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.

  2. 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.

  3. 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.

  4. Application of Kinetic Models in Describing Soil Potassium Release Characteristics and Their Correlations with Potassium Extracted by Chemical Methods

    Institute of Scientific and Technical Information of China (English)

    A.R.HOSSEINPUR; H.R.MOTAGHIAN

    2013-01-01

    Potassium (K) release characteristics in soil play a significant role in supplying available K.Information on K-release characteristics in soils of central Iran is limited.The objectives of this study were to determine K release characteristics and correlations of K release rate constants with K extracted by different chemical methods in surface soils of ten calcareous soils of central Iran.The kinetics of K release in the soils was determined by successive extraction with 0.01 mol L-1 CaCl2 in a period of 2-2017 h at 25±1 ℃.Soil K was extracted by distilled water,0.5 mol L-1 MgNO3,0.002 mol L-1 SrCl2,0.1 mol L-1 BaCl2,0.01 mol L-1 CaCl2,1 mol L-1 NaCI,1 mol L-1 boiling HNO3,1 mol L-1 NH4OAC,Mehlich 1,0.002 mol L-1 SrCl2 + 0.05 mol L-1 citric acid,and ammonium bicarbonate-diethylenetriamine pentaacetic acid (AB-DTPA).A plot of cumulative amounts of K released showed a discontinuity in slope at 168 h.Thus,two equations were applied to two segments of the total reaction time (2-168 and 168-2 017 h).Cumulative amounts of K released ranged from 55 to 299 mg kg-1 in 2-168 h and from 44 to 119 mg kg-1 in 168-2017 h.Release kinetics of K in the two time segments conformed fairly well to parabolic diffusion,simplified Elovich,and power function models.There was a wide variation in the K release rate constants.Increasingly higher average concentrations of soil K were extracted by distilled water,Mehlich 1,SrCl2,CaCl2,SrCl2 + citric acid,AB-DTPA,MgNO3,NaCl,NH4OAc,BaCl2,and HNO3.Potassium release rate constants were significantly correlated with K extracted.The results of this study showed that information obtained from mathematical modeling in two reaction time segments can help to estimate the K-supplying power of soils.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. Hash: a program to accurately predict protein H{sup {alpha}} shifts from neighboring backbone shifts

    Energy Technology Data Exchange (ETDEWEB)

    Zeng Jianyang, E-mail: zengjy@gmail.com [Tsinghua University, Institute for Interdisciplinary Information Sciences (China); Zhou Pei [Duke University Medical Center, Department of Biochemistry (United States); Donald, Bruce Randall [Duke University, Department of Computer Science (United States)

    2013-01-15

    Chemical shifts provide not only peak identities for analyzing nuclear magnetic resonance (NMR) data, but also an important source of conformational information for studying protein structures. Current structural studies requiring H{sup {alpha}} chemical shifts suffer from the following limitations. (1) For large proteins, the H{sup {alpha}} chemical shifts can be difficult to assign using conventional NMR triple-resonance experiments, mainly due to the fast transverse relaxation rate of C{sup {alpha}} that restricts the signal sensitivity. (2) Previous chemical shift prediction approaches either require homologous models with high sequence similarity or rely heavily on accurate backbone and side-chain structural coordinates. When neither sequence homologues nor structural coordinates are available, we must resort to other information to predict H{sup {alpha}} chemical shifts. Predicting accurate H{sup {alpha}} chemical shifts using other obtainable information, such as the chemical shifts of nearby backbone atoms (i.e., adjacent atoms in the sequence), can remedy the above dilemmas, and hence advance NMR-based structural studies of proteins. By specifically exploiting the dependencies on chemical shifts of nearby backbone atoms, we propose a novel machine learning algorithm, called Hash, to predict H{sup {alpha}} chemical shifts. Hash combines a new fragment-based chemical shift search approach with a non-parametric regression model, called the generalized additive model, to effectively solve the prediction problem. We demonstrate that the chemical shifts of nearby backbone atoms provide a reliable source of information for predicting accurate H{sup {alpha}} chemical shifts. Our testing results on different possible combinations of input data indicate that Hash has a wide rage of potential NMR applications in structural and biological studies of proteins.

  10. Automated two-point dixon screening for the evaluation of hepatic steatosis and siderosis: comparison with R2*-relaxometry and chemical shift-based sequences

    International Nuclear Information System (INIS)

    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.)

  11. 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.)

  12. 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.

  13. Red-Shifting versus Blue-Shifting Hydrogen Bonds: Perspective from Ab Initio Valence Bond Theory.

    Science.gov (United States)

    Chang, Xin; Zhang, Yang; Weng, Xinzhen; Su, Peifeng; Wu, Wei; Mo, Yirong

    2016-05-01

    Both proper, red-shifting and improper, blue-shifting hydrogen bonds have been well-recognized with enormous experimental and computational studies. The current consensus is that there is no difference in nature between these two kinds of hydrogen bonds, where the electrostatic interaction dominates. Since most if not all the computational studies are based on molecular orbital theory, it would be interesting to gain insight into the hydrogen bonds with modern valence bond (VB) theory. In this work, we performed ab initio VBSCF computations on a series of hydrogen-bonding systems, where the sole hydrogen bond donor CF3H interacts with ten hydrogen bond acceptors Y (═NH2CH3, NH3, NH2Cl, OH(-), H2O, CH3OH, (CH3)2O, F(-), HF, or CH3F). This series includes four red-shifting and six blue-shifting hydrogen bonds. Consistent with existing findings in literature, VB-based energy decomposition analyses show that electrostatic interaction plays the dominating role and polarization plays the secondary role in all these hydrogen-bonding systems, and the charge transfer interaction, which denotes the hyperconjugation effect, contributes only slightly to the total interaction energy. As VB theory describes any real chemical bond in terms of pure covalent and ionic structures, our fragment interaction analysis reveals that with the approaching of a hydrogen bond acceptor Y, the covalent state of the F3C-H bond tends to blue-shift, due to the strong repulsion between the hydrogen atom and Y. In contrast, the ionic state F3C(-) H(+) leads to the red-shifting of the C-H vibrational frequency, owing to the attraction between the proton and Y. Thus, the relative weights of the covalent and ionic structures essentially determine the direction of frequency change. Indeed, we find the correlation between the structural weights and vibrational frequency changes. PMID:27074500

  14. Evaluating the correlation between chemical and sensory compounds in Blaufränkisch and Cabernet Franc wines

    OpenAIRE

    Irina Balga; Attila Kiss; Lajos Gál; Annamária Leskó; Miklós Kállay

    2014-01-01

    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 ca...

  15. 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...

  16. 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)

  17. Chemical shift changes provide evidence for overlapping single-stranded DNA and XPA binding sites on the 70 kDa subunit of human replication protein A

    Energy Technology Data Exchange (ETDEWEB)

    Daughdrill, Gary W.; Buchko, Garry W.; Botuyan, Maria V.; Arrowsmith, Cheryl H.; Wold, Marc S.; Kennedy, Michael A.; Lowry, David F.

    2003-07-15

    Replication protein A (RPA) is a heterotrimeric single-stranded DNA (ssDNA) binding protein that can form a complex with the xeroderma pigmentosum group A protein (XPA). This complex can preferentially recognize UV damaged DNA over undamaged DNA and has been implicated in the stabilization of open complex formation during nucleotide excision repair. In this report, NMR spectroscopy was used to investigate the interaction between a fragment of the 70 kDa subunit of human RPA, residues 1-326 (hRPA701-326), and a fragment of the human XPA protein, residues 98-219 (XPA-MBD). Intensity changes were observed for amide resonances in the 1H-15N correlation spectrum of uniformly 15N-labeled hRPA701-326 after the addition of unlabeled XPA-MBD. The intensity changes observed were restricted to an ssDNA binding domain that is between residues 183 and 296 of the hRPA701-326 fragment. The hRPA701-326 residues with the largest resonance intensity reductions were mapped onto the structure of the ssDNA binding domain to identify the binding surface with XPA-MBD. The XPA-MBD binding surface showed significant overlap with an ssDNA binding surface that was previously identified using NMR spectroscopy and X-ray crystallography.

  18. Using NMR chemical shift imaging to monitor swelling and molecular transport in drug-loaded tablets of hydrophobically modified poly(acrylic acid): methodology and effects of polymer (in)solubility.

    Science.gov (United States)

    Knöös, Patrik; Topgaard, Daniel; Wahlgren, Marie; Ulvenlund, Stefan; Piculell, Lennart

    2013-11-12

    A new technique has been developed using NMR chemical shift imaging (CSI) to monitor water penetration and molecular transport in initially dry polymer tablets that also contain small low-molecular weight compounds to be released from the tablets. Concentration profiles of components contained in the swelling tablets could be extracted via the intensities and chemical shift changes of peaks corresponding to protons of the components. The studied tablets contained hydrophobically modified poly(acrylic acid) (HMPAA) as the polymer component and griseofulvin and ethanol as hydrophobic and hydrophilic, respectively, low-molecular weight model compounds. The water solubility of HMPAA could be altered by titration with NaOH. In the pure acid form, HMPAA tablets only underwent a finite swelling until the maximum water content of the polymer-rich phase, as confirmed by independent phase studies, had been reached. By contrast, after partial neutralization with NaOH, the polyacid became fully miscible with water. The solubility of the polymer affected the water penetration, the polymer release, and the releases of both ethanol and griseofulvin. The detailed NMR CSI concentration profiles obtained highlighted the clear differences in the disintegration/dissolution/release behavior for the two types of tablet and provided insights into their molecular origin. The study illustrates the potential of the NMR CSI technique to give information of importance for the development of pharmaceutical tablets and, more broadly, for the general understanding of any operation that involves the immersion and ultimate disintegration of a dry polymer matrix in a solvent. PMID:24106807

  19. Control of Correlations in Sr4V2O6Fe2As2 by Chemical Stoichiometry

    OpenAIRE

    Sefat, Athena S.; Singh, David J.; Garlea, V. Ovidiu; Zuev, Yuri L.; McGuire, Michael A.; VanBebber, Lindsay; Sales, Brian C.

    2010-01-01

    We show using a combination of powder X-ray and neutron diffraction, first principles calculations, temperature- and field-dependent magnetization, heat capacity and resistivity data that the superconducting behavior of `Sr$_4$V$_2$O$_6$Fe$_2$As$_2$' is dependent on synthesis conditions, particularly, heating profiles result in unintentional chemical doping. This compound can be tuned from a state in which the vanadium electrons are itinerant with a high electronic density of states, to a sta...

  20. 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.

  1. 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

  2. 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. PMID:26741561

  3. 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.

  4. 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...

  5. Electrostatic Interactions Are Key to C═O n-π* Shifts: An Experimental Proof.

    Science.gov (United States)

    Haldar, Tapas; Bagchi, Sayan

    2016-06-16

    Carbonyl n-π* transitions are known to undergo blue shift in polar and hydrogen-bonding solvents. Using semiempirical expressions, previous studies hypothesized several factors like change in dipole moment and hydrogen-bond strength upon excitation to cause the blue shift. Theoretically, ground-state electrostatics has been predicted to be the key to the observed shifts, however, an experimental proof has been lacking. Our experimental results demonstrate a consistent linear correlation between IR (ground-state phenomenon) and n-π* frequency shifts (involves both ground and excited electronic-states) of carbonyls in hydrogen-bonded and non-hydrogen-bonded environments. The carbonyl hydrogen-bonding status is experimentally verified from deviation in n-π*/fluorescence correlation. The IR/n-π* correlation validates the key role of electrostatic stabilization of the ground state toward n-π* shifts and demonstrates the electrostatic nature of carbonyl hydrogen bonds. n-π* shifts show linear sensitivity to calculated electrostatic fields on carbonyls. Our results portray the potential for n-π* absorption to estimate local polarity in biomolecules and to probe chemical reactions involving carbonyl activation/stabilization. PMID:27249517

  6. 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.

  7. 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 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. PMID:25437454

  8. 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.

  9. A comparative quantitative analysis of the IDEAL (iterative decomposition of water and fat with echo asymmetry and least-squares estimation) and the CHESS (chemical shift selection suppression) techniques in 3.0 T L-spine MRI

    Science.gov (United States)

    Kim, Eng-Chan; Cho, Jae-Hwan; Kim, Min-Hye; Kim, Ki-Hong; Choi, Cheon-Woong; Seok, Jong-min; Na, Kil-Ju; Han, Man-Seok

    2013-03-01

    This study was conducted on 20 patients who had undergone pedicle screw fixation between March and December 2010 to quantitatively compare a conventional fat suppression technique, CHESS (chemical shift selection suppression), and a new technique, IDEAL (iterative decomposition of water and fat with echo asymmetry and least squares estimation). The general efficacy and usefulness of the IDEAL technique was also evaluated. Fat-suppressed transverse-relaxation-weighed images and longitudinal-relaxation-weighted images were obtained before and after contrast injection by using these two techniques with a 1.5T MR (magnetic resonance) scanner. The obtained images were analyzed for image distortion, susceptibility artifacts and homogenous fat removal in the target region. The results showed that the image distortion due to the susceptibility artifacts caused by implanted metal was lower in the images obtained using the IDEAL technique compared to those obtained using the CHESS technique. The results of a qualitative analysis also showed that compared to the CHESS technique, fewer susceptibility artifacts and more homogenous fat removal were found in the images obtained using the IDEAL technique in a comparative image evaluation of the axial plane images before and after contrast injection. In summary, compared to the CHESS technique, the IDEAL technique showed a lower occurrence of susceptibility artifacts caused by metal and lower image distortion. In addition, more homogenous fat removal was shown in the IDEAL technique.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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

  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. 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.

  18. 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.

  19. 磁共振化学位移成像评估椎体骨髓脂肪含量的应用%Application of assessing fat content of vertebral bone marrow with chemical-shift MRI

    Institute of Scientific and Technical Information of China (English)

    雷立存; 任庆云; 母建奎; 祁宇轩; 何丽; 刘斋

    2015-01-01

    Objective To investigate the feasibility for assessing the fat content of vertebral bone marrow in postmenopausal women with chemical-shift MRI technique..Methods Lumbar vertebral body.(L1-L4)(224 vertebral body) of 56 cases of postmeno-pausal women were selected and all patients were performed with chemical-shift MRI and dual-energy X-ray absorptiometry (DXA).to obtain signal decline index and bone density..The patients were divided into normal group,.osteopenia group and osteoporosis group according to DXA results,.and the difference of signal decline index among three groups was analyzed so as to investigate the law of signal decline index of vertebrae of groups with different bone density. Results 68 subjects in normal group,.72 subjects with osteopenia and 84 subjects with osteoporosis were determined according to DXA results. .The median of vertebrae signal decline index of the three groups (normal group, osteopenia group and osteoporosis group) were 60.57%(67.86%-45.34%),.58.22%.(69.29%-49.49%) and 56.80%.(67.52%-36.00%),.respectively. There was statistically significant difference (P0.05). Conclusion Measuring vertebrae signal decline index with chemical shift MRI can reflect the changes of fat content in patients with osteoporosis, and is of high value in clinical application.%目的:探讨磁共振化学位移成像技术评估绝经后女性椎体骨髓脂肪含量的可行性。方法选取56例绝经后女性患者的腰椎1~4椎体(共计224个椎体),所有患者均行磁共振化学位移成像和双能X线吸收法骨密度测定,得出每个椎体信号下降指数和骨密度值,按照骨密度T分数分为骨量正常组,骨量减少组和骨质疏松组,分析三组椎体信号下降指数的差异,探讨不同骨密度组椎体信号下降指数的变化规律。结果56例患者224个椎体按照T分数进行分组,骨量正常组68个,骨量减少组72个,骨质疏松组84个,骨量正常组,骨量减少组和

  20. 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.

  1. 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.

  2. 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.

  3. 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).

  4. 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). PMID:26733467

  5. 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.

  6. NMR spectroscopy, Hammett correlations and biological activity of some Schiff bases derived from piperonal

    Energy Technology Data Exchange (ETDEWEB)

    Echevarria, Aurea [Universidade Federal Rural do Rio de Janeiro, Itaguai, RJ (Brazil). Dept. de Quimica; Nascimento, Maria da Graca; Geronimo, Vanilde [Santa Catarina Univ., Florianopolis, SC (Brazil). Dept. de Quimica; Miller, Joseph [Paraiba Univ., Joao Pessoa, PB (Brazil); Giesbrecht, Astrea [Sao Paulo Univ., SP (Brazil). Inst. de Ciencias Biomedicas

    1999-07-01

    A series of eleven Schiff Bases have been synthesized. They were obtained by condensation of piperonal (3,4-methylenedioxybenzaldehyde) with the corresponding aromatic primary amines. Their {sup 1}H and {sup 13}C-NMR spectra have been obtained and the Hammett correlations including chemical shifts and the substituent constants ({sigma}{sub p}, {sigma}R e {sigma}I) were studied. Linear and bilinear significant correlations were observed for iminic carbon (C-{alpha}) and C-1{sup '}, showing a more significant resonance effect on chemical shifts. The chemical shifts for C-4{sup '} were highly affected by substituent effects, especially for halogens in the expected direction. Their biological activity against microorganisms has also been measured and significant activity was showed against Epidermophyton floccosum. The biological activity did not give a reasonable relationship with electronic effects. (author)

  7. NMR spectroscopy, Hammett correlations and biological activity of some Schiff bases derived from piperonal

    International Nuclear Information System (INIS)

    A series of eleven Schiff Bases have been synthesized. They were obtained by condensation of piperonal (3,4-methylenedioxybenzaldehyde) with the corresponding aromatic primary amines. Their 1H and 13C-NMR spectra have been obtained and the Hammett correlations including chemical shifts and the substituent constants (σp, σR e σI) were studied. Linear and bilinear significant correlations were observed for iminic carbon (C-α) and C-1', showing a more significant resonance effect on chemical shifts. The chemical shifts for C-4' were highly affected by substituent effects, especially for halogens in the expected direction. Their biological activity against microorganisms has also been measured and significant activity was showed against Epidermophyton floccosum. The biological activity did not give a reasonable relationship with electronic effects. (author)

  8. 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…

  9. 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

  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. 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...

  12. 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.

  13. Transformations of the chemical compositions of high molecular weight DOM along a salinity transect: Using two dimensional correlation spectroscopy and principal component analysis approaches

    Science.gov (United States)

    Abdulla, Hussain A. N.; Minor, Elizabeth C.; Dias, Robert F.; Hatcher, Patrick G.

    2013-10-01

    In a study of chemical transformations of estuarine high-molecular-weight (HMW, >1000 Da) dissolved organic matter (DOM) collected over a period of two years along a transect through the Elizabeth River/Chesapeake Bay system to the coastal Atlantic Ocean off Virginia, USA, δ13C values, N/C ratios, and principal component analysis (PCA) of the solid-state 13C NMR (nuclear magnetic resonance) spectra of HMW-DOM show an abrupt change in both its sources and chemical structural composition occurring around salinity 20. HMW-DOM in the lower salinity region had lighter isotopic values, higher aromatic and lower carbohydrate contents relative to that in the higher salinity region. These changes around a salinity of 20 are possibly due to introduction of a significant amount of new carbon (autotrophic DOM) to the transect. PC-1 loadings plot shows that spatially differing DOM components are similar to previously reported 13C NMR spectra of heteropolysaccharides (HPS) and carboxyl-rich alicyclic molecules (CRAM). Applying two dimensional correlation spectroscopy techniques to 1H NMR spectra from the same samples reveals increases in the contribution of N-acetyl amino sugars, 6-deoxy sugars, and sulfated polysaccharides to HPS components along the salinity transect, which suggests a transition from plant derived carbohydrates to marine produced carbohydrates within the HMW-DOM pool. In contrast to what has been suggested previously, our combined results from 13C NMR, 1H NMR, and FTIR indicate that CRAM consists of at least two different classes of compounds (aliphatic polycarboxyl compounds and lignin-like compounds).

  14. 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.

  15. S-Wave Collisional Frequency Shift of a Fermion Clock

    CERN Document Server

    Hazlett, Eric L; Stites, Ronald W; Gibble, Kurt; O'Hara, Kenneth M

    2012-01-01

    We report an s-wave collisional frequency shift of an atomic clock based on fermions. In contrast to bosons, the fermion clock shift is insensitive to the population difference of the clock states, set by the first pulse area in Ramsey spectroscopy, \\theta_1. The fermion shift instead depends strongly on the second pulse area \\theta_2. It allows the shift to be canceled, nominally at \\theta_2 = \\pi/2, but correlations shift the null to slightly larger \\theta_2. The shift applies to optical lattice clocks and increases with the spatial inhomogeneity of the clock excitation field, naturally large at optical frequencies.

  16. Determination of depth, permeability, and fluid pressure of hydraulically active fractures in the COSC-1 borehole and their correlation with chemical and geophysical logging data

    Science.gov (United States)

    Tsang, Chin-Fu; Doughty, Christine; Rosberg, Jan-Erik; Berthet, Theo; Juhlin, Christopher; Niemi, Auli

    2016-04-01

    appears that the depths of the breakout zones do not correspond to the depths of the hydraulically active fractures. Chemical analyses of water samples from the borehole as a function of depth are currently being conducted. Correlation of these findings with the FFEC results will be presented.

  17. 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.

  18. Correlation between chemical composition and antibacterial activity of essential oils of some aromatic medicinal plants growing in the Democratic Republic of Congo.

    Science.gov (United States)

    Cimanga, K; Kambu, K; Tona, L; Apers, S; De Bruyne, T; Hermans, N; Totté, J; Pieters, L; Vlietinck, A J

    2002-02-01

    The chemical composition of essential oils from 15 aromatic medicinal plant species growing in the Democratic Republic of Congo have been studied. More than 15 constituents in an amount higher than 0.1% were identified in each essential oil. 1,8-cineole, alpha and beta-pinene, p-cymene, myrcene, gamma-terpinene, alpha-terpineol and limonene were prevalent constituents in almost more than 10 selected plant species. Results from the antibacterial testing by the diffusion method indicate that all essential oils (5 microl per disc) inhibited the growth of selected bacteria at different extents. The most active antibacterial essential oils were those of the leaves of Eucalyptus camadulensis and Eucalyptus terticornis (12-30 mm zone diameter of inhibition). They showed particularly a most potent inhibition of Pseudomonas aeruginosa growth (15-16 mm), followed by Eucalyptus robusta (12 mm). Essential oils from the leaves of Eucalyptus alba, Eucalyptus citriodora, Eucalyptus deglupta, Eucalyptus globulus, Eucalyptus saligna, Eucalyptus robusta, Aframomum stipulatum, Cymbopogon citratus, Ocimum americanum and that of the seeds of Monodora myristica showed also a good antibacterial activity (10-18 mm). Eucalyptus propinqua, Eucalyptus urophylla and Ocimum gratissimum essential oils were the less active samples against the selected bacteria. No correlation between the amount of major constituents such as 1,8-cineol, alpha-pinene, p-cymene, cryptone or thymol and the antibacterial activity was observed. PMID:11801384

  19. 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)

  20. 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.

  1. 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

  2. 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

  3. 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.

  4. 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.

  5. 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。

  6. 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

  7. Shifts that divide population

    Science.gov (United States)

    Muneepeerakul, Rachata; Qubbaj, Murad; Aggarwal, Rimjhim; Anderies, John M.; Janssen, Marco

    2014-05-01

    How does a population of organisms in an ecosystem or of people in a society respond to rapid shifts in the environment? Answers to this question are critical to our ability to anticipate and cope with a changing ecohydrological system. We have developed a generic model of adaptation mechanisms, based on replicator dynamics, in which we derive a simple and insightful threshold condition that separates two important types of responses: 'cohesive transition' in which the whole population changes gradually together, and 'population-dividing transition' in which the population splits into two groups with one eventually dominating the other. The threshold depends on the magnitude of the shift and the shape of the fitness landscape. Division in populations can fundamentally alter the functioning of and induce subsequent feedbacks within the system; knowing the condition that gives rise to such division is thus fundamentally important.

  8. Prediction of the brittle-ductile transition temperature shift, from irradiation experiments obtained in France

    International Nuclear Information System (INIS)

    In integrety - evaluation studies of the nuclear-reactor vessel, the toughness of component materials is given by a reference curve, which represents the lowest level of the toughness possible values, as a function of the temperature. Its temperature-scale position is given by the null ductility temperature. In non-irradiated conditions, the temperature of the vessel materials is experimentally obtained. To take into account the irradiation effect, a shift of this temperature, given by the correlations where chemical composition and neutronic dose are included, is considered. Up to date correlations, settled for materials brittler than those applied in the French program, are called in question again. A correlation between results obtained in France since 1973, for base metals and welded joints is given. The behavior of CHOOZ vessel, under irradiation conditions, is discussed

  9. 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.

  10. 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.

  11. 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.

  12. Shifted genus expanded W ∞ algebra and shifted Hurwitz numbers

    Science.gov (United States)

    Zheng, Quan

    2016-05-01

    We construct the shifted genus expanded W ∞ algebra, which is isomorphic to the central subalgebra A ∞ of infinite symmetric group algebra and to the shifted Schur symmetrical function algebra Λ* defined by Okounkov and Olshanskii. As an application, we get some differential equations for the generating functions of the shifted Hurwitz numbers; thus, we can express the generating functions in terms of the shifted genus expanded cut-and-join operators.

  13. Shift rostering using decomposition: assign weekend shifts first

    NARCIS (Netherlands)

    Veen, van der Egbert; Hans, Erwin W.; Post, Gerhard F.; Veltman, Bart

    2015-01-01

    This paper introduces a shift rostering problem that surprisingly has not been studied in the literature: the weekend shift rostering problem. It is motivated by our experience that employees’ shift preferences predominantly focus on the weekends, since many social activities happen during weekends.

  14. 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.

  15. Assignment of hyperfine shifted haem methyl carbon resonances in paramagnetic low-spin met-cyano complex of sperm whale myoglobin

    International Nuclear Information System (INIS)

    The hyperfine shifted resonances arising from all four individual haem carbons of the paramagnetic low-spin met-cyano complex of sperm whale myoglobin have been clearly identified and assigned for the first time with the aid of 1H-13C heteronuclear chemical shift correlated spectroscopy. Alteration of the in-plane symmetry of the electronic structure of haem induced by the ligation of proximal histidyl imidazole spreads the haem carbon resonances to 32 ppm at 220C, indicating the sensitivity of those resonances to the haem electronic/molecular structure. Those resonances are potentially powerful probes in characterizing the nature of haem electronic structure. 25 refs.; 2 figs.; 1 table

  16. Spectroscopy and quantum chemical modeling reveal a predominant contribution of excitonic interactions to the bathochromic shift in alpha-crustacyanin, the blue carotenoprotein in the carapace of the lobster Homarus gammarus.

    Science.gov (United States)

    van Wijk, Arjan A C; Spaans, Arnold; Uzunbajakava, Natallia; Otto, Cees; de Groot, Huub J M; Lugtenburg, Johan; Buda, Francesco

    2005-02-01

    To resolve the molecular basis of the coloration mechanism of alpha-crustacyanin, we used (13)C-labeled astaxanthins as chromophores for solid-state (13)C NMR and resonance Raman spectroscopy of [6,6',7,7']-(13)C(4) alpha-crustacyanin and [8,8',9,9',10,10',11,11',20,20']-(13)C(10) alpha-crustacyanin. We complement the experimental data with time-dependent density functional theory calculations on several models based on the structural information available for beta-crustacyanin. The data rule out major changes and strong polarization effects in the ground-state electron density of astaxanthin upon binding to the protein. Conformational changes in the chromophore and hydrogen-bond interactions between the astaxanthin and the protein can account only for about one-third of the total bathochromic shift in alpha-crustacyanin. The exciton coupling due to the proximity of two astaxanthin chromophores is found to be large, suggesting that aggregation effects in the protein represent the primary source of the color change. PMID:15686376

  17. Chemical recycling of carbon dioxide emissions from a cement plant into dimethyl ether, a case study of an integrated process in France using a Reverse Water Gas Shift (RWGS) step

    International Nuclear Information System (INIS)

    Recycling of carbon dioxide (CO2) and hydrogen (H2) into liquid fuel technology has recently gained wide public interest since it is a potential pathway to increase the liquid fuel supply and to mitigate CO2 emissions simultaneously. In France, the majority of the electricity production is derived from nuclear and renewable energy which have a low CO2 footprint. This electricity power enables a potential for massive hydrogen production with low carbon emissions. We studied the possibility to develop this technology at an industrial scale in the French context on a typical industrial example of a cement manufacture in the south of France. An integrated process is proposed, which enables the use of the heat released by the CO2 to fuel process to help to capture the CO2 released by the cement manufacture. Some technological issues are discussed, and a potential solution is proposed for the catalyst used in the critical step of the Reverse Water Gas-Shift reaction (RWGS) of the process. (authors)

  18. 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.

  19. Correlation of chromosome patterns in human leukemic cells with exposure to chemicals and/or radiation. Progress report, January 1-December 31, 1984

    International Nuclear Information System (INIS)

    Oncogenes associated with human neoplasms are genetically mapped to the human genome. In addition, chromosomal deletions and rearrangements presumably induced by radiotherapy and/or chemotherapy for other maladys are correlated with malignant lymphomas. 27 refs., 6 figs., 2 tabs. (DT)

  20. Study of chemical composition of sludges and scales from the oil production activities and correlation with natural radioactivity - case study: Campos Basin, Brazil

    International Nuclear Information System (INIS)

    This work intended to study general aspects related to natural radioactivity, focusing on its occurrence in the oil industry and on sludge and scales samples taken from the Oil E and P region from Campos's Basin. The physical and chemical analysis and the statistical treatment were carried out with the objective of determine the samples composition checking the differences between the sludges and the scales. Third six representative samples were obtained from the Radioprotection and Dosimetry Institute (IRD/CNEN), Brazil, taking into account factors such as activity concentration, physical and chemical aspects and origin. After the oil extraction, samples were classified by aspects as color and granulometry. Ali the studied samples were analyzed by X-rays diffraction being identified the presence of barite, calcite, quartz among others. The results supplied a base for the elaboration of a successive determination scheme which comprehended residual organic material, carbonate, sulfate, silica, chloride and metals as the alkaline, earthy alkaline, aluminum, etc. The sludges presented a highly variable chemical composition, being rich in silica and carbonates. The main components analysis showed a statistical valid relationship among the radium isotopes and the carbonates presence. On the other hand, the scales are made of barium and strontium sulfates (75%), presenting a minor variation on its chemical composition and in the existing radium content. Due to this low variability of the barium, sulfate and radium contents, it has not been possible to consider valid a relationship that could exist among them in the application of the main component analysis. (author)

  1. 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。

  2. Shift work in a security environment

    International Nuclear Information System (INIS)

    Human beings are diurnal species, normally active by day and asleep by night. Yet over thirty million Americans struggle with work schedules that include an off-normal work effort. The railroads, law enforcement, health services, Department of Defense, factory workers, chemical plants and public services, communications and utility workers must provide some form of around-the-clock effort. Shift work has been around since the advent of recorded history. There has always been a need for some type of off-normal service and assistance. The impact of shift work is replete with tales and factual evidence of an increased personnel error rate; disorders, both personal and family, and of course, increased accident events. In recent memory, the Three Mile Island Nuclear Plant incident, Union Carbide's explosion in Bhopal, and the Chernobyl Nuclear Plant catastrophe all occurred during off-normal working hours. Yet management overall has done little to correct the production-driven twelve hour, seven day week shift mentality of the nineteenth century. Most schedules in use today are nothing more than cosmetic variations of the old production schedules. This could be driven by a management consideration of the worker's response to change coupled with a reluctant buy-in of responsibility for the effects of change. Florida Power Corporation has developed for its nuclear security force, a unique work schedule which attempts to employ the sound principles of circadian rhythms coupled with a comprehensive training program to counter the problems associated with shift work. The results over the last four years have seen a marked reduction in the generic problems of personnel errors, absenteeism, unscheduled overtime and turnover rates. Utilization and understanding of this scheduling process for rotational shift work needs to be assessed to determine if the benefits are site specific or provide an expected response to the problems of shift work

  3. Spatial correlation as leading indicator of catastrophic shifts

    NARCIS (Netherlands)

    Dakos, V.; Nes, van E.H.; Donangelo, R.; Fort, H.; Scheffer, M.

    2010-01-01

    Generic early-warning signals such as increased autocorrelation and variance have been demonstrated in time-series of systems with alternative stable states approaching a critical transition. However, lag times for the detection of such leading indicators are typically long. Here, we show that incre

  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. New Phase Shifting Algorithms Insensitive to Linear Phase Shift Errors

    Directory of Open Access Journals (Sweden)

    J. Novák

    2002-01-01

    Full Text Available This article describes and analyses multistep algorithms for evaluating of the wave field phase in interferometric measurements using the phase shifting technique. New phase shifting algorithms are proposed, with a constant but arbitrary phase shift between captured frames of the intensity of the interference field. The phase evaluation process then does not depend on linear phase shift errors. A big advantage of the described algorithms is their ability to determine the phase shift value at every point of the detector plane. A detailed analysis of these algorithms with respect to main factors that affect interferometric measurements is then carried out. The dependency of these algorithms on phase shift values is also studied several phase calculation algorithms are proposed. These are compared with respect to the resulting phase errors.

  6. 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

  7. 1H-MAS-NMR Chemical Shifts in Hydrogen-Bonded Complexes of Chlorophenols (Pentachlorophenol, 2,4,6-Trichlorophenol, 2,6-Dichlorophenol, 3,5-Dichlorophenol, and p-Chlorophenol) and Amine, and H/D Isotope Effects on 1H-MAS-NMR Spectra

    OpenAIRE

    Hisashi Honda

    2013-01-01

    Chemical shifts (CS) of the 1H nucleus in N···H···O type hydrogen bonds (H-bond) were observed in some complexes between chlorophenols [pentachlorophenol (PCP), 2,4,6-tricholorophenol (TCP), 2,6-dichlorophenol (26DCP), 3,5-dichlorophenol (35DCP), and p-chlorophenol (pCP)] and nitrogen-base (N-Base) by solid-state high-resolution 1H-NMR with the magic-angle-spinning (MAS) method. Employing N-Bases with a wide range of pKa values (0.65–10.75), 1H-MAS-NMR CS values of bridging H atoms in H-bonds...

  8. Antiretroviral therapy: Shifting sands.

    Science.gov (United States)

    Sashindran, V K; Chauhan, Rajeev

    2016-01-01

    HIV/AIDS has been an extremely difficult pandemic to control. However, with the advent of antiretroviral therapy (ART), HIV has now been transformed into a chronic illness in patients who have continued treatment access and excellent long-term adherence. Existing indications for ART initiation in asymptomatic patients were based on CD4 levels; however, recent evidence has broken the shackles of CD4 levels. Early initiation of ART in HIV patients irrespective of CD4 counts can have profound positive impact on morbidity and mortality. Early initiation of ART has been found not only beneficial for patients but also to community as it reduces the risk of transmission. There have been few financial concerns about providing ART to all HIV-positive people but various studies have proven that early initiation of ART not only proves to be cost-effective but also contributes to economic and social growth of community. A novel multidisciplinary approach with early initiation and availability of ART at its heart can turn the tide in our favor in future. Effective preexposure prophylaxis and postexposure prophylaxis can also lower transmission risk of HIV in community. New understanding of HIV pathogenesis is opening new vistas to cure and prevention. Various promising candidate vaccines and drugs are undergoing aggressive clinical trials, raising optimism for an ever-elusive cure for HIV. This review describes various facets of tectonic shift in management of HIV. PMID:26900224

  9. 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.

  10. 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.)

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. Shape-shifting colloids via stimulated dewetting.

    Science.gov (United States)

    Youssef, Mena; Hueckel, Theodore; Yi, Gi-Ra; Sacanna, Stefano

    2016-01-01

    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. PMID:27426418

  17. Portable shift register

    International Nuclear Information System (INIS)

    An electronics package for a small, battery-operated, self-contained, neutron coincidence counter based on a portable shift-register (PSR) has been developed. The counter was developed for applications not adequately addressed by commercial packages, including in-plant measurements to demonstrate compliance with regulations (domestic and international), in-plant process control, and in-field measurements (environmental monitoring or safeguards). Our package's features, which address these applications, include the following: Small size for portability and ease of installation;battery or mains operation; a built-in battery to power the unit and a typical detector such as a small sample counter, for over 6 h if power lines are bad or noisy, if there is a temporary absence of power, or if portability is desired; complete support, including bias, for standard neutron detectors; a powerful communications package to easily facilitate robust external control over a serial port; and a C-library to simplify creating external control programs in computers or other controllers. Whereas the PSR specifically addresses the applications mentioned above, it also performs all the measurements made by previous electronics packages for neutron coincidence counters developed at Los Alamos and commercialized. The PSR electronics package, exclusive of carrying handle, is 8 by 10 by 20 cm; it contains the circuit boards, battery, and bias supply and weighs less than 2 kg. This instrument package is the second in an emerging family of portable measurement instruments being developed; the first was the Miniature and Modular Multichannel Analyzer (M3CA). The PSR makes extensive use of hardware and software developed for the M3CA; like the M3CA, it is intended primarily for use with an external controller interfaced over a serial channel

  18. analysis of some human-daily - used products and studying the correlation between elemental content and possible health harm using chemical and nuclear analytical techniques

    International Nuclear Information System (INIS)

    radiochemical and chemical techniques have been used for analysis of some human-daily-used products. these techniques were: instrumental neutron activation analysis (INAA), and inductively coupled plasma mass spectrometry (ICP-MS). the first technique was used for simultaneously multi-element determination of some trace, minor, and major elements in the analyzed samples, whereas icp-ms was used for analysis of Cd,Cu,Hg, and Pb in some samples. in the present study samples of various products as indicated below were analyzed: 1- samples of various kinds of cosmetic products such as : compact face powder, compact rouge make-up, compact eyeshadow, 2-samples of some common drugs. 3- samples of different kinds of toothpaste, and shaving cream. 4- samples of some mosquitoes exterminators. these samples have been randomly selected from the egyptian market. some of these samples were imported from the world market, and the others were manufactured in Egypt

  19. Instrument Measures Shift In Focus

    Science.gov (United States)

    Steimle, Lawrence J.

    1992-01-01

    Optical components tested at wavelengths from ultraviolet to infrared. Focus-shift-measuring instrument easy to use. Operated in lighted room, without having to make delicate adjustments while peering through microscope. Measures distance along which focal point of converging beam of light shifted by introduction of nominally plane parallel optical component into beam. Intended primarily for measuring focus shifts produced by windows and filters at wavelengths from 120 to 1,100 nanometers. Portable, compact, and relatively inexpensive for degree of precision.

  20. Zero-shifted accelerometer outputs

    Science.gov (United States)

    Galef, Arnold

    1986-08-01

    It is claimed that the commonly appearing zero-shift in pyroshock data is usually a symptom of a malfunctioning measurement system, so that the data can not be repaired (by high-pass filtering or equivalent) unless tests can be devised that permit the demonstration that the system is operating in a linear mode in all respects other than the shift. The likely cause of the zero-shift and its prevention are discussed.

  1. 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.

  2. [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. PMID:24175511

  3. [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.

  4. Correlative microscopy.

    Science.gov (United States)

    Loussert Fonta, Céline; Humbel, Bruno M

    2015-09-01

    In recent years correlative microscopy, combining the power and advantages of different imaging system, e.g., light, electrons, X-ray, NMR, etc., has become an important tool for biomedical research. Among all the possible combinations of techniques, light and electron microscopy, have made an especially big step forward and are being implemented in more and more research labs. Electron microscopy profits from the high spatial resolution, the direct recognition of the cellular ultrastructure and identification of the organelles. It, however, has two severe limitations: the restricted field of view and the fact that no live imaging can be done. On the other hand light microscopy has the advantage of live imaging, following a fluorescently tagged molecule in real time and at lower magnifications the large field of view facilitates the identification and location of sparse individual cells in a large context, e.g., tissue. The combination of these two imaging techniques appears to be a valuable approach to dissect biological events at a submicrometer level. Light microscopy can be used to follow a labelled protein of interest, or a visible organelle such as mitochondria, in time, then the sample is fixed and the exactly same region is investigated by electron microscopy. The time resolution is dependent on the speed of penetration and fixation when chemical fixatives are used and on the reaction time of the operator for cryo-fixation. Light microscopy can also be used to identify cells of interest, e.g., a special cell type in tissue or cells that have been modified by either transfections or RNAi, in a large population of non-modified cells. A further application is to find fluorescence labels in cells on a large section to reduce searching time in the electron microscope. Multiple fluorescence labelling of a series of sections can be correlated with the ultrastructure of the individual sections to get 3D information of the distribution of the marked proteins: array

  5. Correlation between Sensory Evaluation and the Chemical and Microbiological Composition of Yoghourt%酸奶的感官与理化特性和乳酸菌活菌数的相关性

    Institute of Scientific and Technical Information of China (English)

    李俊芳; 康灵芝

    2015-01-01

    在前期酸奶工艺优化的基础上,对酸奶进行感官评分和理化、微生物检测,对酸奶感官评分与理化、微生物指标之间的相关性进行研究。结果表明:黏度、酸度、乳酸菌活菌数和持水性与感官特性有极显著的相关性,由此提出以黏度、酸度和乳酸菌活菌数以及持水性4个指标来客观评价酸奶品质,为酸奶的研制提供理论依据。%On the basis of the previous research about the process optimization of yoghourt. The yoghourt was analyzed by the method of sensory evaluation and the chemical and microbiological composition , and the relationship between the sensory evaluation and the chemical and microbiological composition of yoghourt were explored. The viscosity, acidity, water holding capacity and viable count of lactobacillus of yoghourt were significantly correlated with their sensory scores.Therefore, the Viscosity, acidity, water holding capacity and viable count of lactobacillus were applied to evaluate the quality of yoghourt. objectively , which will provide theoretical basis for the application of The chemical and microbiological composition in the yoghourt quality evaluation.

  6. Correlation between mobility collapse and carbon impurities in Si-doped GaN grown by low pressure metalorganic chemical vapor deposition

    Science.gov (United States)

    Kaess, Felix; Mita, Seiji; Xie, Jingqiao; Reddy, Pramod; Klump, Andrew; Hernandez-Balderrama, Luis H.; Washiyama, Shun; Franke, Alexander; Kirste, Ronny; Hoffmann, Axel; Collazo, Ramón; Sitar, Zlatko

    2016-09-01

    In the low doping range below 1 × 1017 cm-3, carbon was identified as the main defect attributing to the sudden reduction of the electron mobility, the electron mobility collapse, in n-type GaN grown by low pressure metalorganic chemical vapor deposition. Secondary ion mass spectroscopy has been performed in conjunction with C concentration and the thermodynamic Ga supersaturation model. By controlling the ammonia flow rate, the input partial pressure of Ga precursor, and the diluent gas within the Ga supersaturation model, the C concentration in Si-doped GaN was controllable from 6 × 1019 cm-3 to values as low as 2 × 1015 cm-3. It was found that the electron mobility collapsed as a function of free carrier concentration, once the Si concentration closely approached the C concentration. Lowering the C concentration to the order of 1015 cm-3 by optimizing Ga supersaturation achieved controllable free carrier concentrations down to 5 × 1015 cm-3 with a peak electron mobility of 820 cm2/V s without observing the mobility collapse. The highest electron mobility of 1170 cm2/V s was obtained even in metalorganic vapor deposition-grown GaN on sapphire substrates by optimizing growth parameters in terms of Ga supersaturation to reduce the C concentration.

  7. Flexible Schedules and Shift Work.

    Science.gov (United States)

    Beers, Thomas M.

    2000-01-01

    Flexible work hours have gained prominence, as more than 25 million workers (27.6% of all full-time workers) can now vary their schedules. However, there has been little change since the mid-1980s in the proportion who work a shift other than a regular daytime shift. (JOW)

  8. 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

  9. Explaining (Missing) Regulator Paradigm Shifts

    DEFF Research Database (Denmark)

    Wigger, Angela; Buch-Hansen, Hubert

    2014-01-01

    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...

  10. TIPS (trigger an IIF paradigm shift)

    International Nuclear Information System (INIS)

    5 had no severe (recordable) injuries -Biggest total injury type was ergonomic -Biggest recordable injury type (58%) was cuts/lacerations -Chemical exposure and inhalations resulted in no recordables - Biggest root cause category was behavioral -Biggest behavioral root cause was 'Failure to Evaluate Hazards' - Biggest administrative controls root cause was 'Inadequate Procedures' - Biggest engineering controls root cause was 'Unrecognized Workplace Hazard' - Majority of injuries occurred in Spring/Summer which accounted for 86% of recordables -Response was inadequate or poor for 25% of injuries - Number of injuries by workgroup were about equal -Work area injuries were mostly in the CUB and Subfab but CUB injuries favored cuts/lacerations while Subfab favored ergonomic injuries These learnings and gaps were used to develop our New Mexico Site Safety Action Plan for 2005. It has also been used by individual managers and supervisors in their day-to-day business meetings, activities, and communications, for a more focused IIF message and effort. Results: Conclusions/Recommendations: Challenges are different amongst shifts. Shift culture may be stronger than workgroup culture. Work areas pose different challenges that all should be aware of and prepared for. We should prepare ourselves for challenges posed by the Spring and Summer seasons as well. We should be aware of and prepare for the different challenges and cultures characteristic of each shift. Supervisors need to spend more time in the field with their people to help them address safety issues and help make IIF a more consistent component of daily workgroup culture. Each site should analyze their data and look for their unique safety challenges. This will allow customized, focused action plans that meet the unique needs of each site

  11. 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.

  12. 1H-MAS-NMR Chemical Shifts in Hydrogen-Bonded Complexes of Chlorophenols (Pentachlorophenol, 2,4,6-Trichlorophenol, 2,6-Dichlorophenol, 3,5-Dichlorophenol, and p-Chlorophenol and Amine, and H/D Isotope Effects on 1H-MAS-NMR Spectra

    Directory of Open Access Journals (Sweden)

    Hisashi Honda

    2013-04-01

    Full Text Available Chemical shifts (CS of the 1H nucleus in N···H···O type hydrogen bonds (H-bond were observed in some complexes between chlorophenols [pentachlorophenol (PCP, 2,4,6-tricholorophenol (TCP, 2,6-dichlorophenol (26DCP, 3,5-dichlorophenol (35DCP, and p-chlorophenol (pCP] and nitrogen-base (N-Base by solid-state high-resolution 1H-NMR with the magic-angle-spinning (MAS method. Employing N-Bases with a wide range of pKa values (0.65–10.75, 1H-MAS-NMR CS values of bridging H atoms in H-bonds were obtained as a function of the N-Base’s pKa. The result showed that the CS values were increased with increasing pKa values in a range of DpKa 2: The maximum CS values was recorded in the PCP (pKa = 5.26–4-methylpyridine (6.03, TCP (6.59–imidazole (6.99, 26DCP (7.02–2-amino-4-methylpyridine (7.38, 35DCP (8.04–4-dimethylaminopyridine (9.61, and pCP (9.47–4-dimethylaminopyridine (9.61 complexes. The largest CS value of 18.6 ppm was recorded in TCP–imidazole crystals. In addition, H/D isotope effects on 1H-MAS-NMR spectra were observed in PCP–2-amino-3-methylpyridine. Based on the results of CS simulation using a B3LYP/6-311+G** function, it can be explained that a little changes of the N–H length in H-bond contribute to the H/D isotope shift of the 1H-MAS-NMR peaks.

  13. Structure correlation and chemistry

    International Nuclear Information System (INIS)

    The main goal of crystal and molecular structure determination is to provide a starting point for understanding the physical, chemical and biological properties of matter. At present, results from nearly 300000 crystal structure studies are available in computer-readable form. Structure correlation attempts to extract knowledge and understanding from this body of information, which is not available from its parts. This article reviews some typical examples: libraries of prototypal molecular dimensions, mappings of chemical reaction pathways, correlations between structure on one hand and energy, reaction rate, catalytic activity or magnetism on the other. The knowledge gained from structure-correlation studies, together with quantum-chemical and other modeling techniques, provides conceptual and practical tools for designing molecules and materials with tailor-made properties. (orig.)

  14. [Shift work and cardiometabolic risk].

    Science.gov (United States)

    Copertaro, Alfredo; Barbaresi, Mariella; Bracci, Massimo

    2009-11-01

    Shift work is frequently associated with coronary heart disease. Medical research indicate metabolic disturbance among shift workers, which is characterized by associated modifications in the concentration of serum glucose and serum lipids, hypertension and obesity, especially addominal weight. Atrasversal study has been carried out: 193 (126 females and 67 males) healthcare shift workers were compared with 221 (160 females and 61 males) day workers. Medical history, health examination including anthropometric and arterial blood pressure measurements were assessed. All participants were submitted a standardized questionnaire on health-related behaviours and biochemical determinations (fasting plasma glucose, HDL-cholesterol, triglycerides). Job seniority of shift work resulted at 13.5 +/- 8.2 among shift workers and 19.0 +/- 11.3 among day workers. Assessment of the metabolic syndrome relevance was defined according to the criterions proposed by the International Diabetes Federation. The 20% shift workers (33% males and 13% females) was affected by metabolic syndrome against 12% non shift workers (20% males and 9% females). The most frequently altered parameter, apart from metabolic syndrome, was high abdominal obesity, which occurred in 64% of the sample (70% shift workers vs 58% day workers). The results of multiple logistic regression attested the presence of a higher relative risk among shift workers regarding both the prevalence of a metabolic syndrome (OR 2,1 - 95% Cl 1.15-3.86) and the excess in abdominal obesity (OR 1.8 - 95% Cl 1.16-3.25). After adjusting confusing factors such as smoke, age, alchool, consumption, physical activity, scholastic degree, a OR 2.9 - 95%Cl 1,53-5.53 and a OR 1.9 - 95%.Cl 1.32-3.86 were confirmed. PMID:20066881

  15. 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、

  16. Chemical shift imprint of intersubunit communication in a symmetric homodimer.

    Science.gov (United States)

    Falk, Bradley T; Sapienza, Paul J; Lee, Andrew L

    2016-08-23

    Allosteric communication is critical for protein function and cellular homeostasis, and it can be exploited as a strategy for drug design. However, unlike many protein-ligand interactions, the structural basis for the long-range communication that underlies allostery is not well understood. This lack of understanding is most evident in the case of classical allostery, in which a binding event in one protomer is sensed by a second symmetric protomer. A primary reason why study of interdomain signaling is challenging in oligomeric proteins is the difficulty in characterizing intermediate, singly bound species. Here, we use an NMR approach to isolate and characterize a singly ligated state ("lig1") of a homodimeric enzyme that is otherwise obscured by rapid exchange with apo and saturated forms. Mixed labeled dimers were prepared that simultaneously permit full population of the lig1 state and isotopic labeling of either protomer. Direct visualization of peaks from lig1 yielded site-specific ligand-state multiplets that provide a convenient format for assessing mechanisms of intersubunit communication from a variety of NMR measurements. We demonstrate this approach on thymidylate synthase from Escherichia coli, a homodimeric enzyme known to be half-the-sites reactive. Resolving the dUMP1 state shows that active site communication occurs not upon the first dUMP binding, but upon the second. Surprisingly, for many sites, dUMP1 peaks are found beyond the limits set by apo and dUMP2 peaks, indicating that binding the first dUMP pushes the enzyme ensemble to further conformational extremes than the apo or saturated forms. The approach used here should be generally applicable to homodimers. PMID:27466406

  17. 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 u...

  18. 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...

  19. 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

  20. 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 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...... 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....

  1. Semantic Shift in Plant Names

    OpenAIRE

    DOSKOČILOVÁ, Iveta

    2014-01-01

    The aim of the present work is to identify and list English plant names coined by semantic shift, namely by metaphor, metonymy or synecdoche, and to carry out a detailed categorisation of individual semantic categories based on different tendencies within them and interpretation of the results. The theoretical part of my work focuses on different approaches to semantic shift and its categories. It is followed by the practical part which deals individually with metaphor, metonymy and synecdoch...

  2. 压力波对豚鼠耳蜗血管纹、毛细胞心钠素免疫活性改变的研究%Change of Atrial Natriuretic Peptides Immunoreactivity in Stria Vascularis and Hair Cells of Cochlear and Correlation Study of Auditory Threshold Shift After Shock Wave

    Institute of Scientific and Technical Information of China (English)

    陈合新; 邱建华; 王锦玲

    2000-01-01

    目的为探讨压力波的致聋机理,对豚鼠耳蜗血管纹(SV)、毛细胞(HC)中心钠素免疫活性(ANP-IR)的改变及与听阈阈移的相关性进行研究。方法采用免疫细胞化学(ABC法)法、图像分析听性脑干反应测听技术(ABR)对压力波暴露后不同时间分组的豚鼠耳蜗SV、HC中ANP-IR产物进行检测。结果压力波暴露后6、12、24h和48h组SV组织中ANP-IR光密度值较对照组均有明显的差异(P<0.05),其中24h组最高;冲击波暴露后6、12、24h组内毛细胞(IHC)中ANP-IR阳性产物的光密度值较对照组明显增高(P<0.05),其中以12 h组最高。二者的变化均与听阈阈移有明显的正相关性(r1=0.8175,P>0.05;r2=0.9185,P>0.05)。而外毛细胞(OHC)中ANP-IR阳性产物变化不明显。结论压力波暴露后,SV组织中ANP的增高可能是内耳的一种代偿机制;IHC和OHC中ANP-IR的变化可能是冲击波对其损伤机制的不同表现。%Objective In order to investigate the effects of shock wave on atrial natriuretic peptides immunoreactivity in the stria vascularis and hair cells of cochlear and correlation of auditory threshold shift,to study the mechanism of deafness caused by blast trauma. Methods After shock wave, different groups of guinea pigs were studied by ABC immunohistochemistry, image analysis and auditory brainstem response. Results ANP - IR optic density in experimental group was higher than that of control in the stria vascularis and inner hair cells. The change of ANP- IR optic density was directy correlated with ABR threshold shift (r2 =0.9185. P2<0.05). There was no change of ABR and ANP - IR optic density on outer hair cells. Conclusion The change of ANP in the stria vascularis may be a compensatory mechanism to heating lose caused by shock wave; ANP in inner cells may be a pathological manifestation of shock wave. The changes of ANP - IR in outer cells may be a false appearance, it was the shock wave which

  3. 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....

  4. 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

  5. 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。

  6. SAT in shift manager training

    International Nuclear Information System (INIS)

    EDF has improved the organization of the operation shift teams with the replacement of shift supervisor in shift manager function. The shift manager is not only responsible for tasks associated to plant operation (production), but he is also responsible for safety of these tasks and for management of shift team members. A job analysis of this new job position has been performed in order to design the training programme. It resulted in a 10-month training programme that includes 8 weeks in safety-related topics and 12 weeks in soft-skills related topics. The safety related training courses are mandatory, the other courses are optional courses depending on individual trainee needs. The training also includes the development of management competencies. During the 10 month period, each trainee develops an individual project that is evaluated by NPP manager. As well, as group project is undertaken by the trainees and overseen by a steering committee. The steering committee participates in the evaluation process and provides operational experience feedback to the trainee groups and to the overall programme

  7. 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

  8. Correlation of Tobacco Chemical Components and Sensory Quality Assessed by PLSR%基于PLSR分析烟叶化学成分与感官质量的相关性

    Institute of Scientific and Technical Information of China (English)

    林顺顺; 张晓鸣

    2016-01-01

    Partial least squares regression (PLSR) was employed to analyze the correlation of tobacco chemical components and sensory quality. The results showed that sugar/alkaloids and sugar/nitrogen had positive correlations with comfortable and aftertaste attributes, and negative correlations with irritation and off-taste attributes. Additionally, alkaline composition including total alkaloids and volatile alkali had significant negative correlations with aroma quality attributes (p<0.05). Total nitrogen, total alkaloids, protein, volatile alkali and petroleum ether extracts contributed significantly to the increase of irritation, while total sugars and reducing sugars had significant effect on masking harsh-taste (p<0.05). K, Cl and volatile acids contributed to the increase of the sensory comfortable attribute, and the reduction of sensory impact (p<0.05). PLSR solved the multiple linear regression problems in which the use of traditional multivariate methods is severely limited, such as limited number of observations and collinearity. The results of this study are important for guiding cigarette tobacco processing and modifying technology.%采用偏最小二乘回归(PLSR)方法对烟叶化学成分与感官质量的关系进行了分析.结果表明,糖碱比和糖氮比与感官刺激性、杂气呈显著负相关,与柔细度、余味显著正相关(p<0.05).此外,总植物碱、挥发碱对香气质具有显著负影响(p<0.05);总氮、总植物碱、蛋白质、挥发碱及石油醚提取物显著贡献于感官刺激性的增强,而水溶性总糖、还原糖对消除杂气具有显著贡献(p<0.05);K、Cl、挥发酸对增强感官柔细度,降低劲头具有显著贡献(p<0.05).PLSR解决了传统分析方法中的观察值数量限制及数据共线性等问题.

  9. 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.

  10. The shifting foundations of nursing.

    Science.gov (United States)

    Law, Kate; Aranda, Kay

    2010-08-01

    In this paper we argue that the concerns generated by the development of Foundation Degrees and the Assistant and Associate Practitioner roles have rekindled some of the unresolved debates regarding the status and identity of nursing and nurses. Through the application of the sociological theories of professionalisation and nostalgia we have identified the shifting and unresolved nature of nursing. We argue that these theories continue to have resonance in the current climate of change and 'upskilling' of the health care workforce and argue, that the shifts illuminated are perhaps so significant as to demonstrate that we have entered a post-nursing era.

  11. 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.

  12. Leadership Shifts in Changing Field

    Science.gov (United States)

    Zubrzycki, Jaclyn

    2013-01-01

    As groups representing local and state education players struggle to remain relevant in a policy conversation often dominated by foundations, think tanks, new advocacy groups, and political and business figures, a shift in leadership has been under way at major associations. Most of the changes have come as part of the natural churn; former…

  13. 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…

  14. Magnetic shift of magic nuclei

    International Nuclear Information System (INIS)

    The shell effect of nuclei in strong magnetic fields associated with magnetars' is considered within the shell model. It is demonstrated that the magnetic field gives rise to a change of the phase in shell-oscillations of nuclear masses. The nuclear magic numbers of the iron region are shifted significantly towards smaller mass numbers. (author)

  15. The ALICE Glance Shift Accounting Management System (SAMS)

    Science.gov (United States)

    Martins Silva, H.; Abreu Da Silva, I.; Ronchetti, F.; Telesca, A.; Maidantchik, C.

    2015-12-01

    ALICE (A Large Ion Collider Experiment) is an experiment at the CERN LHC (Large Hadron Collider) studying the physics of strongly interacting matter and the quark-gluon plasma. The experiment operation requires a 24 hours a day and 7 days a week shift crew at the experimental site, composed by the ALICE collaboration members. Shift duties are calculated for each institute according to their correlated members. In order to ensure the full coverage of the experiment operation as well as its good quality, the ALICE Shift Accounting Management System (SAMS) is used to manage the shift bookings as well as the needed training. ALICE SAMS is the result of a joint effort between the Federal University of Rio de Janeiro (UFRJ) and the ALICE Collaboration. The Glance technology, developed by the UFRJ and the ATLAS experiment, sits at the basis of the system as an intermediate layer isolating the particularities of the databases. In this paper, we describe the ALICE SAMS development process and functionalities. The database has been modelled according to the collaboration needs and is fully integrated with the ALICE Collaboration repository to access members information and respectively roles and activities. Run, period and training coordinators can manage their subsystem operation and ensure an efficient personnel management. Members of the ALICE collaboration can book shifts and on-call according to pre-defined rights. ALICE SAMS features a user profile containing all the statistics and user contact information as well as the Institutes profile. Both the user and institute profiles are public (within the scope of the collaboration) and show the credit balance in real time. A shift calendar allows the Run Coordinator to plan data taking periods in terms of which subsystems shifts are enabled or disabled and on-call responsible people and slots. An overview display presents the shift crew present in the control room and allows the Run Coordination team to confirm the presence

  16. 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 ...

  17. 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.

  18. Superadditive correlation.

    Science.gov (United States)

    Giraud, B G; Heumann, J M; Lapedes, A S

    1999-05-01

    The fact that correlation does not imply causation is well known. Correlation between variables at two sites does not imply that the two sites directly interact, because, e.g., correlation between distant sites may be induced by chaining of correlation between a set of intervening, directly interacting sites. Such "noncausal correlation" is well understood in statistical physics: an example is long-range order in spin systems, where spins which have only short-range direct interactions, e.g., the Ising model, display correlation at a distance. It is less well recognized that such long-range "noncausal" correlations can in fact be stronger than the magnitude of any causal correlation induced by direct interactions. We call this phenomenon superadditive correlation (SAC). We demonstrate this counterintuitive phenomenon by explicit examples in (i) a model spin system and (ii) a model continuous variable system, where both models are such that two variables have multiple intervening pathways of indirect interaction. We apply the technique known as decimation to explain SAC as an additive, constructive interference phenomenon between the multiple pathways of indirect interaction. We also explain the effect using a definition of the collective mode describing the intervening spin variables. Finally, we show that the SAC effect is mirrored in information theory, and is true for mutual information measures in addition to correlation measures. Generic complex systems typically exhibit multiple pathways of indirect interaction, making SAC a potentially widespread phenomenon. This affects, e.g., attempts to deduce interactions by examination of correlations, as well as, e.g., hierarchical approximation methods for multivariate probability distributions, which introduce parameters based on successive orders of correlation. PMID:11969452

  19. Two approaches to the blind phase shift extraction for two-step electronic speckle pattern interferometry

    Science.gov (United States)

    Muravsky, Leonid; Kmet', Arkady; Voronyak, Taras

    2013-10-01

    A two-step electronic speckle pattern interferometry (ESPI) method with blind phase shift of a reference wave, in which the phase shift extraction is fulfilled by using both a correlation and a discrete Fourier transform (DFT) approaches, is presented here. In the correlation approach, the blind phase shift is calculated via the correlation coefficient between two similar speckle interferograms (SI) differing only by the reference wave phase shift. The DFT approach is based on the blind phase shift extraction from frequency components of SI Fourier spectra. Comparative analysis of these approaches has testified to their high performance. Moreover, it is shown that the correlation approach is more preferable for blind phase shift extraction from SIs with a rough surface than from interferograms with a smooth surface; hence, it is more convenient for ESPI than for phase-shifting interferometry. In addition, this approach provides a lesser level of systematic error of extracted phase shift in comparison with the DFT. The correlation approach was used for experimental definition of Poisson's ratio for duralumin constructional material by the two-step ESPI method.

  20. Predator-induced phenotypic plasticity in Daphnia pulex: Uncoupling morphological defenses and life history shifts

    NARCIS (Netherlands)

    Repka, S.; Pihlajamaa, K.

    1996-01-01

    Chemical cues from a predator Chaoborus sp. induce morphological defense (neck spine) and life history shifts (later reproduction, decreased fecundity but larger juvenile size) in the waterflea Daphnia pulex. These shifts have been interpreted either as costs of defense or as separate adaptation. In