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1

Production of 199Ir via Exotic Nucleon Transfer Reaction  

NASA Astrophysics Data System (ADS)

A new nucleus 199Ir has been produced using the exotic transfer reaction 198Pt(18O, 17F)199Ir at 140 MeV. The mass of 199Ir has been measured by the determination of the reaction Q value. Its mass excess is -24.424 ± 0.034 MeV.

Zhao, Kui; J, Lilley S.; P, Drumm V.; D, Warner D.; R, Cunningham A.; J, Mo N.

1993-05-01

2

FT-IR and {sup 1}H NMR characterization of the products of an ethylene inverse diffusion flame  

SciTech Connect

Knowledge of the chemical structure of young soot and its precursors is very useful in the understanding of the paths leading to soot particle inception. This paper presents analyses of the chemical functional groups, based on FT-IR and {sup 1}H NMR spectroscopy of the products obtained in an ethylene inverse diffusion flame. The trends in the data indicate that the soluble fraction of the soot becomes progressively more aromatic and less aliphatic as the height above the burner increases. Results from {sup 1}H NMR spectra of the chloroform-soluble soot samples taken at different heights above the burner corroborate the infrared results based on proton chemical shifts (Ha, H{alpha}, H{beta}, and H{gamma}). The results indicate that the aliphatic {beta} and {gamma} hydrogens suffered the most drastic reduction, while the aromatic character increased considerably with height, particularly in the first half of the flame. (author)

Santamaria, Alexander; Mondragon, Fanor [Institute of Chemistry, University of Antioquia, A.A. 1226, Medellin (Colombia); Molina, Alejandro [Combustion Research Facility, Sandia National Laboratories, Livermore, CA 94551 (United States); Marsh, Nathan D.; Eddings, Eric G.; Sarofim, Adel F. [Department of Chemical Engineering, University of Utah, Salt Lake City, UT 84112 (United States)

2006-07-15

3

Click Reaction: Highly Efficient Synthesis of 2,3-Dihydroquinazolin-4(1H)-ones  

Microsoft Academic Search

In this work, condensation reaction of 2-aminobenzamide with various alkyl, aryl, and alicyclic aldehydes or ketones to 2,3-dihydroquinazolin-4(1H)-one derivatives in the presence of a catalytic amount of ammonium chloride in ethanol at room temperature is described. This reaction can be classified as a click chemical synthesis because of its high yields, short reaction times, and green and efficient reaction medium.

Ahmad Shaabani; Ali Maleki; Hamid Mofakham

2008-01-01

4

IR, 1H NMR, mass, XRD and TGA/DTA investigations on the ciprofloxacin/iodine charge-transfer complex  

NASA Astrophysics Data System (ADS)

The charge-transfer complex (CTC) of ciprofloxacin drug (CIP) as a donor with iodine (I 2) as a sigma acceptor has been studied spectrophotometrically in CHCl 3. At maximum absorption bands, the stoichiometry of CIP:iodine system was found to be 1:1 ratio according to molar ratio method. The essential spectroscopic data like formation constant ( KCT), molar extinction coefficient ( ?CT), standard free energy (? G°), oscillator strength ( f), transition dipole moment ( ?), resonance energy ( RN) and ionization potential ( ID) were estimated. The spectroscopic techniques such as IR, 1H NMR, mass and UV-vis spectra and elemental analyses (CHN) as well as TG-DTG and DTA investigations were used to characterize the chelating behavior of CIP/iodine charge-transfer complex. The iodine CT interaction was associated with a presence of intermolecular hydrogen bond. The X-ray investigation was carried out to investigate the iodine doping in the synthetic CT complex.

Refat, Moamen S.; El-Hawary, W. F.; Moussa, Mohamed A. A.

2011-05-01

5

Experimental (FT-IR, FT-Raman, 1H NMR) and theoretical study of magnesium, calcium, strontium, and barium picolinates  

NASA Astrophysics Data System (ADS)

The experimental IR, Raman, and 1H NMR spectra of picolinic acid, as well as magnesium, calcium, strontium, and barium picolinates were registered, assigned and studied. Characteristic changes in the spectra of metal picolinates in comparison with the spectrum of ligand were observed, which lead to the conclusion that perturbation of the aromatic system of picolinates increases along with the series Mg ? Ca ? Sr ? Ba. Theoretical structures of beryllium and magnesium picolinates, as well as theoretical IR spectrum of magnesium picolinate were calculated in B3PW91/6-311++G(d, p) level. On the basis of calculated bond lengths in pyridine ring geometric, aromaticity indexes HOMA were calculated. The idea of these indexes is based on the fact that the essential factor in aromatic stabilization is the ? delocalization manifested in: planar geometry, equalization of the bond lengths and angles, and symmetry. The decidedly lower value of HOMA for magnesium picolinate (i.e. 0.545; 0.539) than that for beryllium picolinate (i.e. 0.998; 0.998) indicate higher aromatic properties of Be picolinate than of Mg picolinate. The comparison of theoretical and literature experimental structures of magnesium picolinate was done. The experimental structure contains two water molecules, so the calculations for hydrated magnesium picolinate were carried on, and the influence of coordinated water molecule on the structure of picolinates was discussed. The HOMAs for hydrated experimental and calculated Mg picolinate amount to 0.870; 0.743, and 0.900; 0.890, respectively, whereas for anhydrous structure, it is as described above, i.e. 0.545; 0.539. Thus, the calculations clearly showed that water molecules coordinated to the central atom weakens the effect of metal on the electronic system of ligand.

?widerski, G.; Kalinowska, M.; Wojtulewski, S.; Lewandowski, W.

2006-05-01

6

Search for the Halo Effect in the 1H(6He, 6Li)n Reaction  

NASA Astrophysics Data System (ADS)

The angular distributions of the charge exchange reaction 1H(6He, 6Li)n were measured in reverse kinematics with a secondary 6He beam at the energy of 4.17 A MeV. The data were analysed in the context of a microscopic calculation. It is shown that both the ground state of 6He and the second excited state of 6Li (3.563 MeV, 0+) have a halo structure.

Li, Zhi-Hong; Liu, Wei-Ping; Bai, Xi-Xiang; Wang, You-Bao; Lian, Gang; Li, Zhi-Chang; Shen, Qing-Biao; Lin, Cheng-Jian; Zeng, Sheng; Fu, Chang-Bo

2002-03-01

7

Organocatalyzed enantioselective aldol reaction of 1H-pyrrole-2,3-diones  

PubMed Central

The enantioselective cross aldol reaction of 1-benzyl 4,5-dioxo-2-aryl-4,5-dihydro-1H-pyrrole-3-carboxylates and ketones was studied with proline derivatives or cinchona alkaloid-derived primary amines as the catalysts for the first time. trans-4-Benzoyloxy-L-proline (15) was found to be the best catalyst for acyclic ketones. For cyclohexanone, the best results were achieved with 9-deoxy-9-epi-aminoquinine (18) as the catalyst in the presence of racemic 1,1'-binaphthyl-2,2'-diyl hydrogen phosphate (19) as the cocatalyst. Using these protocols, 3-alkyl-3-hydroxy-1H-pyrrol-2(3H)-one derivatives were obtained in excellent yields and good to high ee values (up to 94% ee).

Bhanushali, Mayur

2011-01-01

8

Discovering [superscript 13]C NMR, [superscript 1]H NMR, and IR Spectroscopy in the General Chemistry Laboratory through a Sequence of Guided-Inquiry Exercises  

ERIC Educational Resources Information Center

|This sequence of three guided-inquiry labs is designed for a second-semester general chemistry course and challenges students to discover basic theoretical principles associated with [superscript 13]C NMR, [superscript 1]H NMR, and IR spectroscopy. Students learn to identify and explain basic concepts of magnetic resonance and vibrational…

Iler, H. Darrell; Justice, David; Brauer, Shari; Landis, Amanda

2012-01-01

9

Longitudinal and Transverse Cross Sections in the 1H\\\\(e, e'K+\\\\)Lambda Reaction  

Microsoft Academic Search

The 1H\\\\(e,e'K+\\\\)Lambda reaction was studied as a function of the squared four-momentum transfer, Q2, and the virtual photon polarization, ?. For each of four Q2 settings, 0.52, 0.75, 1.00, and 2.00 \\\\(GeV\\/c\\\\)2, the longitudinal and transverse virtual photon cross sections were extracted in measurements at three virtual photon polarizations. The Q2 dependence of the sigmaL\\/sigmaT ratio differs significantly from current

Gabriel Niculescu; R. M. Mohring; P. Gueye; D. Abbott; A. Ahmidouch; Ts. A. Amatuni; P. Ambrozewicz; T. Angelescu; C. S. Armstrong; K. Assamagan; S. Avery; K. Bailey; O. K. Baker; K. Beard; S. Beedoe; E. Beise; H. Breuer; R. Carlini; J. Cha; C. C. Chang; N. Chant; E. Cisbani; G. Collins; W. Cummings; S. Danagoulian; R. de Leo; F. Duncan; J. Dunne; D. Dutta; T. Eden; R. Ent; L. Eyraud; L. Ewell; M. Finn; T. Fortune; V. Frolov; S. Frullani; C. Furget; F. Garibaldi; D. Gaskell; D. F. Geesaman; K. K. Gustafsson; J.-O. Hansen; M. Harvey; W. Hinton; E. Hungerford; M. Iodice; C. Jackson; C. Keppel; W. Kim; K. Kino; D. Koltenuk; S. Kox; L. Kramer; T. Leone; G. Lolos; A. Lung; D. Mack; R. Madey; M. Maeda; S. Majewski; P. Markowitz; C. J. Martoff; D. Meekins; A. Mihul; J. Mitchell; H. Mkrtchyan; S. Mtingwa; I. Niculescu; R. Perrino; D. Potterveld; J. W. Price; B. A. Raue; J.-S. Real; J. Reinhold; P. Roos; T. Saito; G. Savage; R. Sawafta; R. Segel; S. Stepanyan; P. Stoler; V. Tadevosian; L. Tang; L. Teodorescu; T. Terasawa; H. Tsubota; G. M. Urciuoli; J. Volmer; W. Vulcan; P. Welch; R. Williams; S. Wood; C. Yan; B. Zeidman

1998-01-01

10

Separation of the longitudinal and transverse cross sections in the 1H(e,e'K+)Lambda and 1H(e,e'K+)Sigma0 reactions  

Microsoft Academic Search

We report measurements of cross sections for the reaction 1H(e,e'K+)Y, for both the Lambda and Sigma0 hyperon states, at an invariant mass of W=1.84 GeV and four-momentum transfers 0.5

R. M. Mohring; D. Abbott; A. Ahmidouch; Ts. A. Amatuni; P. Ambrozewicz; T. Angelescu; C. S. Armstrong; J. Arrington; K. Assamagan; S. Avery; K. Bailey; K. Beard; S. Beedoe; E. J. Beise; H. Breuer; R. Carlini; J. Cha; C. C. Chang; N. Chant; E. Cisbani; G. Collins; W. Cummings; S. Danagoulian; R. de Leo; F. Duncan; J. Dunne; D. Dutta; T. Eden; R. Ent; L. Eyraud; L. Ewell; M. Finn; T. Fortune; V. Frolov; S. Frullani; C. Furget; F. Garibaldi; D. Gaskell; D. F. Geesaman; P. Gueye; K. K. Gustafsson; J.-O. Hansen; M. Harvey; W. Hinton; E. Hungerford; M. Iodice; C. Jackson; C. Keppel; W. Kim; K. Kino; D. Koltenuk; S. Kox; L. Kramer; T. Leone; A. Lung; D. Mack; R. Madey; M. Maeda; S. Majewski; P. Markowitz; T. Mart; C. J. Martoff; D. Meekins; A. Mihul; J. Mitchell; H. Mkrtchyan; S. Mtingwa; I. Niculescu; R. Perrino; D. Potterveld; J. W. Price; B. A. Raue; J.-S. Real; J. Reinhold; P. Roos; T. Saito; G. Savage; R. Sawafta; R. Segel; S. Stepanyan; P. Stoler; V. Tadevosian; L. Tang; L. Teodorescu; T. Terasawa; H. Tsubota; G. M. Urciuoli; J. Volmer; W. Vulcan; T. P. Welch; R. Williams; S. Wood; C. Yan; B. Zeidman

2003-01-01

11

Neutron-hole states in 45Ar from 1H(46Ar, d) 45Ar reactions  

NASA Astrophysics Data System (ADS)

To improve the effective interactions in the pf shell, it is important to measure the single-particle and single-hole states near the N = 28 shell gap. In this paper, the neutron spectroscopic factors of hole states from the unstable neutron-rich 45Ar (Z = 18,N = 27) nucleus have been studied using the 1H(46Ar,d) 45Ar transfer reaction in inverse kinematics. Comparison of our results with the particle states of 45Ar produced in 2H(44Ar, p) 45Ar reaction shows that the two reactions populate states with different angular momenta. Using the angular distributions, we are able to confirm the spin assignments of four low-lying states of 45Ar. These are the ground state (f7/2), the first-excited state (p3/2), and the s1/2 and d3/2 states. While large basis shell-model predictions describe spectroscopic properties of the ground and p3/2 states very well, they fail to describe the s1/2 and d3/2 hole states.

Lu, F.; Lee, Jenny; Tsang, M. B.; Bazin, D.; Coupland, D.; Henzl, V.; Henzlova, D.; Kilburn, M.; Lynch, W. G.; Rogers, A. M.; Sanetullaev, A.; Sun, Z. Y.; Youngs, M.; Charity, R. J.; Sobotka, L. G.; Famiano, M.; Hudan, S.; Horoi, M.; Ye, Y. L.

2013-07-01

12

The spectroscopic (FT-IR, FT-Raman and 1H, 13C NMR) and theoretical studies of cinnamic acid and alkali metal cinnamates  

NASA Astrophysics Data System (ADS)

The effect of alkali metals (Li ? Na ? K ? Rb ? Cs) on the electronic structure of cinnamic acid (phenylacrylic acid) was studied. In this research many miscellaneous analytical methods, which complement one another, were used: infrared (FT-IR), Raman (FT-Raman), nuclear magnetic resonance (1H, 13C NMR) and quantum mechanical calculations. The spectroscopic studies lead to conclusions concerning the distribution of the electronic charge in molecule, the delocalization energy of ?-electrons and the reactivity of metal complexes. The change of metal along with the series: Li ? Na ? K ? Rb ? Cs caused: (1) the change of electronic charge distribution in cinnamate anion what is seen via the occurrence of the systematic shifts of several bands in the experimental and theoretical IR and Raman spectra of cinnamates, (2) systematic chemical shifts for protons 1H and 13C nuclei.

Kalinowska, Monika; ?wis?ocka, Renata; Lewandowski, W?odzimierz

2007-05-01

13

1 H NMR, IR and UV\\/VIS Spectroscopic Studies of Some Schiff Bases Derived From 2-Aminobenzothiazole and 2Amino3-hydroxypyridine  

Microsoft Academic Search

By condensing 2-aminobenzothiazole with 2-hydroxy-1-naphthaldehyde, 2-hydroxybenzaldehyde, 4-methoxybenzaldehyde, 4-hydroxybenzal-dehyde, benzaldehyde and 4-dimethylaminobenzaldehyde, and five Schiff bases Ia-Ie are prepared. Also, two Schiff bases IIa and IIb are prepared by condensation of 2-amino-3-hydroxypyridine with 2-hydroxy-1-naphthaldehyde and 2-hydroxybenzaldehyde. The 1H NMR, IR and UV\\/Vis spectra of these seven Schiff bases are investigated. The signals of the 1 HN MR spectra as well as

Raafat M. Issa; Abdalla M. Khedr; Helen Rizk

14

Preparation, UV–Vis, IR and 1H NMR spectra, and molecular structure of the complex ion (? 2-carbonato)(?,?,?,?-tetrakis ( o-pivalamidophenyl)porphinato)ferrate(III)  

Microsoft Academic Search

An iron(III) porphyrin complex containing a bidentate carbonato axial ligand has been synthesized for the first time and fully characterized by UV–Vis, IR and 1H NMR spectroscopies and X-ray crystallography. Proton NMR data for the isolated species is in accordance with high-spin (S=5\\/2) ferric derivative. The crystal structure of the (cryptand-222)potassium(+) (dihaptocarbonato)(?,?,?,?-terakis(o-pivalamidophenyl)(porphinato)ferrate(III) chlorobenzene has been determined. This structure confirms the

Mondher Dhifet; Mohamed Salah Belkhiria; Michel Giorgi; Habib Nasri

2009-01-01

15

FT-IR, 1H, 13C NMR, ESI-MS and semiempirical investigation of the structures of Monensin phenyl urethane complexes with the sodium cation  

NASA Astrophysics Data System (ADS)

In this paper three forms of phenyl urethane of Monensin i.e. its acid form (H-MU) and its 1:1 complex with NaClO4 (H-MU-Na) and its sodium salt (Na-MU) were obtained and their structures were studied by FT-IR, 1H and 13C NMR, ESI MS and PM5 methods. The FT-IR data of Na-MU complexes demonstrate that the Cdbnd O urethane group is not engaged in the complexation of the sodium cation. However spectroscopic studies of H-MU-Na complex show that the structure in which this Cdbnd O urethane groups participate in the complexation is also present, but it is in the minority. The PM5 semiempirical calculations allow visualisation of all structures and determination of the hydrogen bond parameters.

Huczy?ski, Adam

2013-06-01

16

Molecular structures of 3,6-di(hexylthioureido)acridine conformers, their protonation, 1H NMR and IR analyses: Theoretical and experimental studies  

NASA Astrophysics Data System (ADS)

The optimized structures of the 3,6-di(hexylthioureido)acridine conformers were obtained using density functional theory (DFT) and ONIOM methods. Three conformers of 3,6-di(hexylthioureido)acridine and their corresponding protonated forms were found. Single-point energies calculations were obtained using second-order Møller Plesset at the MP2(fc)/6-31G(d) level. The computed 1H NMR chemical shifts referenced to TMS in DMSO for all conformers were obtained. The presence of symmetrical conformers of the neutral and protonated structures were confirmed by the 1H NMR measurement. The measured and computed IR spectra of the neutral and protonated species of 3,6-di(hexylthioureido)acridine were obtained and compared.

Keawwangchai, Somchai; Tuntulani, Thawatchai; Ruangpornvisuti, Vithaya

2007-04-01

17

Concentration and solvent effects on the conformational equilibrium of cis-3-ethoxycyclohexanol by 1H NMR and IR spectroscopy  

NASA Astrophysics Data System (ADS)

NMR data, in CCl4, show that an increase in the concentration of cis-3-ethoxycyclohexanol (cis-3-ECH) shifts the conformational equilibrium from the ax ax conformer (Xax ax=51% at 0.01 mol L-1), stabilized by an intramolecular hydrogen bond (IAHB), to the eq eq conformer (Xeq eq=67% at 0.40 mol L-1), which forms intermolecular hydrogen bonds (IEHB), as confirmed by IR data. The ?? values, obtained by IR spectra, indicated that cis-3-ECH presents a stronger IAHB than the cis-3-methoxycyclohexanol, due to the increase in substituent steric and group electronegativity effects. The percentage of eq eq conformer also increases with the solvent basicity, from 51% (?Geqeq axax=-0.03 kcal mol-1 in CCl4 to 97% (?Geqeq axax=-2.05 kcal mol-1) in DMSO. Values of 4.58 and 5.39 kcal mol-1, for the IAHB strength in cis-3-ECH, were obtained from the theoretical data at CBS-4M and B3LYP/6-311+G** levels, respectively.

de Oliveira, Paulo R.; Ortiz, Danilo S.; Rittner, Roberto

2006-05-01

18

UV/Vis, IR and 1H NMR spectrophotometric studies of some bisazo-dianil compounds based on bis-(hydroxy, formyl) phenylazo phenylene and anthranilic acid  

NASA Astrophysics Data System (ADS)

The electronic absorption spectra of some bisazo-dianils are studied in organic solvents of different polarity and in buffer solutions of varied pH. The different absorption bands are assigned to the corresponding electronic transitions, the solvent effect on the CT band energy is also discussed. The spectral study in buffer solutions is utilized for the determination of the p Ka of the phenolic OH-groups. The important bands in the IR spectra as well as the signals of the 1H NMR spectra are assigned and discussed in relation to molecular structure. The fluorescence spectra of the compounds are recorded. The fluorescence quantum yield and p K in the ground and excited states are determined.

Issa, Raafat M.; El-baradie, Kamal Y.; El-Wakiel, Nadia A.

2004-10-01

19

Behavior of phenol (phenol-d5) on NaX zeolite as studied by 1H NMR and FT-IR techniques  

NASA Astrophysics Data System (ADS)

The reactivity and behavior of phenol (phenol-d5) on NaX zeolite at different temperatures have been studied by 1H MAS NMR and FT-IR techniques. An interaction between hydroxyl of phenol and zeolite framework oxygen atoms has been revealed, favouring the transfer of H(D) atoms of phenolic hydroxyl to zeolite framework to give phenolate ions. In phenol, the isotope exchange between H(D) atoms of phenolic hydroxyl and those of ring occurs mainly at ortho and para positions. The formation of phenolate ions changes the isotope exchange to meta position. The formation of phenol to phenolate ions is enhanced on NaX zeolite, explaining the high O-alkylation selectivity observed in phenol alkylation with methanol.

Beutel, Tilman; Su, Bao-Lian

2005-11-01

20

Crystal structure and theoretical study of IR and 1H and 13C NMR spectra of cordatin, a natural product with antiulcerogenic activity  

NASA Astrophysics Data System (ADS)

Cordatin is a furan diterpenoid with a clerodane skeleton isolated from Croton palanostigma Klotzsch (Euphorbiaceae). This natural product shows significant antiulcerogenic activity, similar to cimetidine (Tagamet®), a compound used for the treatment of peptic ulcers. The crystal structure of cordatin was obtained by X-ray diffraction and its geometrical parameters were compared with theoretical calculations at the B3LYP theory level. The IR and NMR (1H and 13C chemical shifts and coupling constants) spectra were obtained and compared with the theoretical calculations. The B3LYP theory level, with the 6-31G(d,p) and 6-311G(d,p) basis set, provided IR absorption values close to the experimental data. Moreover, theoretical NMR parameters obtained in both gas phase and chloroform solvent at the B3PW91/DGDZVP, B3LYP/6-311+G(2d,p), and B3PW91/6-311+G(2d,p) levels showed good correlations with the experimental results.

Brasil, Davi S. B.; Alves, Cláudio N.; Guilhon, Giselle M. S. P.; Muller, Adolfo H.; Secco, Ricardo De S.; Peris, Gabriel; Llusar, Rosa

21

Angular dependence of the Doppler broadening in the resonance of the 1H(15N, alphagamma)12C reaction  

Microsoft Academic Search

We provide the first direct demonstration of the three-dimensional vibrational motion of hydrogen monoatomically chemisorbed at the bridge sites on a well defined W(001) surface in beta1 phase, by the Doppler broadening in the narrow resonance of the 1H(15H, alphagamma)12C (Eres = 6.385 MeV) reaction. The beam-incident angle (theta) dependence of the Doppler width shows that the mean square of

Yasushi Iwata

1991-01-01

22

Isomeric [RuCl2(dmso)2(indazole)2] complexes: ruthenium(II)-mediated coupling reaction of acetonitrile with 1H-indazole.  

PubMed

Reaction of the antitumor complex trans-[Ru(III)Cl4(Hind)2]- (Hind = indazole) with an excess of dimethyl sulfoxide (dmso) in acetone afforded the complex trans,trans,trans-[Ru(II)Cl2(dmso)2(Hind)2] (1). Two other isomeric compounds trans,cis,cis-[Ru(II)Cl2(dmso)2(Hind)2] (2) and cis,cis,cis-[Ru(II)Cl2(dmso)2(Hind)2] (3) have been obtained on refluxing cis-[Ru(II)Cl(2)(dmso)(4)] with 2 equiv. of indazole in ethanol and methanol, respectively. Isomers 1 and 2 react with acetonitrile yielding the complexes trans-[Ru(II)Cl2(dmso)(Hind){HN=C(Me)ind}].CH3CN (4.CH3CN) and trans,cis-[Ru(II)Cl2(dmso)2{HN=C(Me)ind}].H2O (5.H2O), respectively, containing a cyclic amidine ligand resulting from insertion of the acetonitrile C triple bond N group in the N1-H bond of the N2-coordinated indazole ligand in the nomenclature used for 1H-indazole. These are the first examples of the metal-assisted iminoacylation of indazole. The products isolated have been characterized by elemental analysis, IR spectroscopy, UV-vis spectroscopy, electrospray mass-spectrometry, thermogravimetry, differential scanning calorimetry, 1H NMR spectroscopy, and solid-state 13C CP MAS NMR spectroscopy. The isomeric structures of 1-3 and the presence of a chelating amidine ligand in 4 and 5 have been confirmed by X-ray crystallography. The electrochemical behavior of 1-5 and the formation of 5 have been studied by cyclic voltammetry. PMID:15995743

Reisner, Erwin; Arion, Vladimir B; Rufi?ska, Anna; Chiorescu, Ion; Schmid, Wolfgang F; Keppler, Bernhard K

2005-06-15

23

FT-IR, UV–vis, 1H and 13C NMR spectra and the equilibrium structure of organic dye molecule disperse red 1 acrylate: A combined experimental and theoretical analysis  

Microsoft Academic Search

This study reports the characterization of disperse red 1 acrylate compound by spectral techniques and quantum chemical calculations. The spectroscopic properties were analyzed by FT-IR, UV–vis, 1H NMR and 13C NMR techniques. FT-IR spectrum in solid state was recorded in the region 4000–400cm?1. The UV–vis absorption spectrum of the compound that dissolved in methanol was recorded in the range of

Mehmet Cinar; Ali Coruh; Mehmet Karabacak

2011-01-01

24

Measurement of T20(90°) in the 1H(d-->,?)3He reaction below deuteron breakup threshold  

NASA Astrophysics Data System (ADS)

The tensor analyzing powers of the 1H(d-->,?)3He reaction are sensitive to the tensor component of the nucleon-nucleon force, which mixes the L=2 D state into the 3He ground state wave function. Modern Faddeev calculations of this reaction allow a quantitative comparison to the parametrization of the tensor force in the trinucleon system. The T20 analyzing power was measured at an incident beam energy of 5.25 MeV and a laboratory angle of 90° (?c.m.=92.9°), where the comparison to theory is especially rigorous. The measured value of T20(90°lab) is -0.035+/-0.004, which differs by ~=3? from a recent Faddeev calculation which uses the separable expansion of the Paris potential.

Browne, K. P.; Pitts, W. K.; Smith, M. K.; McAninch, J. E.; Knutson, L. D.

1996-10-01

25

Regioselective aromatic substitution reactions of cyclometalated Ir(III) complexes: synthesis and photochemical properties of substituted Ir(III) complexes that exhibit blue, green, and red color luminescence emission.  

PubMed

In this manuscript, the regioselective halogenation, nitration, formylation, and acylation of Ir(tpy)(3) and Ir(ppy)(3) (tpy = 2-(4'-tolyl)pyridine and ppy = 2-phenylpyridine) and the subsequent conversions are described. During attempted bromination of the three methyl groups in fac-Ir(tpy)(3) using N-bromosuccinimide (NBS) and benzoyl peroxide (BPO), three protons at the 5'-position (p-position with respect to the C-Ir bond) of phenyl rings in tpy units were substituted by Br, as confirmed by (1)H NMR spectra, mass spectra, and X-ray crystal structure analysis. It is suggested that such substitution reactions of Ir complexes proceed via an ionic mechanism rather than a radical mechanism. UV-vis and luminescence spectra of the substituted Ir(III) complexes are reported. The introduction of electron-withdrawing groups such as CN and CHO groups at the 5'-position of tpy induces a blue shift of luminescence emission to about 480 nm, and the introduction of electron-donating groups such as an amino group results in a red shift to about 600 nm. A reversible change of emission for the 5'-amino derivative of Ir(tpy)(3), Ir(atpy)(3), between red and green occurs upon protonation and deprotonation. PMID:21214169

Aoki, Shin; Matsuo, Yasuki; Ogura, Shiori; Ohwada, Hiroki; Hisamatsu, Yosuke; Moromizato, Shinsuke; Shiro, Motoo; Kitamura, Masanori

2011-01-07

26

New modification of the Perkow reaction: halocarboxylate anions as leaving groups in 3-acyloxyquinoline-2,4(1H,3H)-dione compounds  

PubMed Central

Substituted 3-(fluoroacyloxy)quinoline-2,4(1H,3H)-diones including 3-(fluoroiodoacetoxy) derivatives react with triethyl phosphite to afford either the product of the Perkow reaction or the corresponding 4-ethoxyquinolin-2(1H)-one. In both reactions, the fluorocarboxylate anion acts as the first observed leaving group. This observation restricts the application of the intramolecular Horner-Wadsworth-Emmons synthesis to modify quinoline-2,4(1H,3H)-diones by the annulation of fluorinated but-2-enolide rings.

Paleta, Oldrich; Pomeisl, Karel; Kafka, Stanislav; Klasek, Antonin; Kubelka, Vladislav

2005-01-01

27

Channelling experiments on the lattice location of hydrogen in metals using the nuclear reaction 1H(11B, ?)??  

NASA Astrophysics Data System (ADS)

In order to locate hydrogen dissolved in metals a nuclear reaction 1H(11B, ?)?? was applied to a channelling method. As an example of this application the results of the following two experiments were briefly reported. (1) The lattice location of H in V was investigated under a <001> compressive stress of 7 kg/mm2 below the elastic limit. The configuration of hydrogen is extremely sensitive to compressive stress and changes from a tetrahedral (T) site to a diplaced-T or 4T configuration. On release of this stress the hydrogen atoms returned to T-sites. (2) To elucidate the mechanism of the enhancement of the terminal solubility for hydrogen (TSH) in Nb on alloying with undersized Mo atoms, the state of hydrogen was studied in Nb-based Nb-Mo dilute alloys. It was demonstrated that H atoms are trapped by Mo atoms and located at sites displaced from T-sites by about 0.6 Å. This result supports the trapping model for the enhancement of the TSH in the region of low Mo concentration.

Yagi, Eiichi

1992-03-01

28

Experimental (FT-IR, FT-Raman and UV-Vis spectra) and density functional theory calculations of diethyl 1H-pyrazole-3,5-dicarboxylate  

NASA Astrophysics Data System (ADS)

The vibrational and electronic spectra of diethyl 1H-pyrazole-3,5-dicarboxylate (DE1H35DC) are reported and discussed. In this work the structural properties and vibrational frequencies of diethyl 1H-pyrazole-3,5-dicarboxylate have been investigated extensively using density functional theory (DFT) employing B3LYP exchange correlation with the normal basis level 6-31G(d,p). The first hyperpolarizabilities and electric dipole moments of the said molecule have been computed using quantum mechanical calculations. NBO and HOMO, LUMO analysis has been carried out. The geometries and normal modes of vibrations obtained from B3LYP calculations are in good agreement with the experimentally observed data.

Udaya Sri, N.; Chaitanya, Kadali; Prasad, M. V. S.; Veeraiah, V.; Veeraiah, A.

2012-07-01

29

Separation of the longitudinal and transverse cross sections in the {sup 1}H(e,e{prime} K{sup +}){Lambda} and {sup 1}H(e,e{prime} K{sup +}){Sigma}{sup 0} reactions  

SciTech Connect

We report measurements of cross sections for the reaction {sup 1}H(e,e{prime} K{sup +})Y, for both the {Lambda} and {Sigma}{sup 0} hyperon states, at an invariant mass of W = 1.84 GeV and four-momentum transfers 0.5 < Q{sup 2} < 2 (GeV/c){sup 2}. Data were taken for three values of virtual photon polarization {epsilon}, allowing the decomposition of the cross sections into longitudinal and transverse components. The {Lambda} data are a revised analysis of prior work, whereas the {Sigma}{sup 0} results have not been previously reported.

R.M. Mohring; David Abbott; Abdellah Ahmidouch; Thomas Amatuni; Pawel Ambrozewicz; Tatiana Angelescu; Christopher Armstrong; John Arrington; Ketevi Assamagan; Steven Avery; Kevin Bailey; Kevin Beard; S Beedoe; Elizabeth Beise; Herbert Breuer; Roger Carlini; Jinseok Cha; C. Chang; Nicholas Chant; Evaristo Cisbani; Glenn Collins; William Cummings; Samuel Danagoulian; Raffaele De Leo; Fraser Duncan; James Dunne; Dipangkar Dutta; T Eden; Rolf Ent; Laurent Eyraud; Lars Ewell; John Finn; H. Terry Fortune; Valera Frolov; Salvatore Frullani; Christophe Furget; Franco Garibaldi; David Gaskell; Donald Geesaman; Paul Gueye; Kenneth Gustafsson; Jens-Ole Hansen; Mark Harvey; Wendy Hinton; Ed Hungerford; Mauro Iodice; Ceasar Jackson; Cynthia Keppel; Wooyoung Kim; Kouichi Kino; Douglas Koltenuk; Serge Kox; Laird Kramer; Antonio Leone; Allison Lung; David Mack; Richard Madey; M Maeda; Stanislaw Majewski; Pete Markowitz; T Mart; C Martoff; David Meekins; A. Mihul; Joseph Mitchell; Hamlet Mkrtchyan; Sekazi Mtingwa; Maria-Ioana Niculescu; R. Perrino; David Potterveld; John Price; Brian Raue; Jean Sebastien Real; Joerg Reinhold; Philip Roos; Teijiro Saito; Geoff Savage; Reyad Sawafta; Ralph Segel; Stepan Stepanyan; Paul Stoler; Vardan Tadevosyan; Liguang Tang; Liliana Teodorescu; Tatsuo Terasawa; Hiroaki Tsubota; Guido Urciuoli; Jochen Volmer; William Vulcan; T. Welch; Robert Williams; Stephen Wood; Chen Yan; Benjamin Zeidman

2003-05-19

30

Experimental and theoretical studies on the functionalization reactions of 4-benzoyl-1,5-diphenyl-1 H -pyrazole-3-carboxylic acid and-acid chloride with various aminophenols  

Microsoft Academic Search

The 1H-pyrazole-3-carboxylic acid 1 was converted via reactions of its acid chloride 2 with various aminophenol derivatives 3a--d into the corresponding N-(hydroxyphenyl)-1H-pyrazole-3-carboxamides 4a--d, respectively, in good yields (34–53%). The reactions of 1 or 2 with 3 in benzene or toluene for 5–7 h with no catalytic amounts of base lead to the formation of the products 4. The structures of all

Ismail Y?ld?r?m; Fatma Kandemirli

2006-01-01

31

Molecular motions contributions to optical nonlinearity of N-benzyl-2-methyl-4-nitroaniline studied by temperature-dependent FT-IR, 1H NMR spectroscopy and DFT calculations  

NASA Astrophysics Data System (ADS)

The fourier transform infrared (FT-IR) spectra of polycrystalline orthorhombic N-benzyl-2-methyl-4-nitroaniline (BNA) were recorded in the 380-4000 cm-1 region within the 11-297 K temperature range while the 1H NMR spin-lattice relaxation time and the second moment of 1H NMR resonance line were measured in the 145-373 K and 80-400 K temperature range, respectively. Above 80 K the methyl group rotation is found to be dominant among other motions and leading to a significant reduction of the proton second moment which agrees with proposed models for the rigid structure and for the internal rotations in the BNA crystal such as methyl group C3 rotation, phenyl ring rotation and trans-gauche motion of methylene group. Activation energies for the nitro and methyl group rotations were experimentally estimated by FT-IR and 1H NMR, appropriately. For comparison the potential barriers for these two group motions in BNA molecule were calculated by DFT quantum chemical methods. The role of molecular motions in the BNA crystal in the large temperature range is discussed from the point of view of its nonlinear optical properties.

Piela, Katarzyna; Ho?derna-Natkaniec, Krystyna; Baranowski, Miko?aj; Misiaszek, Tomasz; Baran, Jan; Magdalena Szostak, M.

2013-02-01

32

Spectroscopic (FT-IR, FT-Raman, UV absorption, 1H and 13C NMR) and theoretical (in B3LYP/6-311++G** level) studies on alkali metal salts of caffeic acid.  

PubMed

The effect of some metals on the electronic system of benzoic and nicotinic acids has recently been investigated by IR, Raman and UV spectroscopy [1-3]. Benzoic and nicotinic acids are regarded model systems representing a wide group of aromatic ligands which are incorporated into enzymes. In this work the FT-IR (in solid state and in solution), FT-Raman, UV absorption and (1)H and (13)C NMR spectra of caffeic acid (3,4-dihydroxycinnamic acid) and its salts with lithium, sodium, potassium, rubidium and caesium were registered, assigned and analyzed. The effect of alkali metals on the electronic system of ligands was discussed. Studies of differences in the number and position of bands from the IR, Raman, UV absorption spectra and chemical shifts from NMR spectra allowed to conclude on the distribution of electronic charge in the molecules, the delocalization energy of ? electrons and the reactivity of ligands in metal complexes. Optimized geometrical structures of studied compounds were calculated by B3LYP method using 6-311++G** basis set. Bond lengths, angles and dipole moments for the optimized structures of caffeic acid and lithium, sodium, potassium caffeinates were also calculated. The theoretical wavenumbers and intensities of IR spectra were obtained. The calculated parameters were compared to the experimental characteristics of investigated compounds. Microbial activity of studied compounds was tested against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Proteus vulgaris. PMID:22369898

?wis?ocka, Renata

2012-02-14

33

Spectroscopic (FT-IR, FT-Raman, UV absorption, 1H and 13C NMR) and theoretical (in B3LYP/6-311++G** level) studies on alkali metal salts of caffeic acid  

NASA Astrophysics Data System (ADS)

The effect of some metals on the electronic system of benzoic and nicotinic acids has recently been investigated by IR, Raman and UV spectroscopy [1-3]. Benzoic and nicotinic acids are regarded model systems representing a wide group of aromatic ligands which are incorporated into enzymes. In this work the FT-IR (in solid state and in solution), FT-Raman, UV absorption and 1H and 13C NMR spectra of caffeic acid (3,4-dihydroxycinnamic acid) and its salts with lithium, sodium, potassium, rubidium and caesium were registered, assigned and analyzed. The effect of alkali metals on the electronic system of ligands was discussed. Studies of differences in the number and position of bands from the IR, Raman, UV absorption spectra and chemical shifts from NMR spectra allowed to conclude on the distribution of electronic charge in the molecules, the delocalization energy of ? electrons and the reactivity of ligands in metal complexes. Optimized geometrical structures of studied compounds were calculated by B3LYP method using 6-311++G** basis set. Bond lengths, angles and dipole moments for the optimized structures of caffeic acid and lithium, sodium, potassium caffeinates were also calculated. The theoretical wavenumbers and intensities of IR spectra were obtained. The calculated parameters were compared to the experimental characteristics of investigated compounds. Microbial activity of studied compounds was tested against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Proteus vulgaris.

?wis?ocka, Renata

34

Three Component Reaction: An Efficient Synthesis and Reactions of 3,4-Dihydropyrimidin-2(1H)-Ones and Thiones Using New Natural Catalyst  

PubMed Central

Synthesis of 3,4-dihydropyrimidin-2(1H)-one and 3,4-dihydropyrimidin-2(1H)-thione derivatives from aldehydes, 1,3-dicarbonyl derivatives and urea or thiourea using granite and quartz as new, natural and reusable catalysts. Some of the 3,4-dihydropyrimidin-2(1H)-thione derivatives were used to prepare new heterocyclic compounds. The antimicrobial activity of selected examples of the synthesized compounds was tested and showed moderate activity.

Elmaghraby, A. M.; Mousa, I. A.; Harb, A. A.; Mahgoub, M. Y.

2013-01-01

35

Vibrational spectroscopic (FT-IR, FT-Raman, 1H NMR and UV) investigations and computational study of 5-nitro-2-(4-nitrobenzyl) benzoxazole  

NASA Astrophysics Data System (ADS)

The optimized molecular structure, vibrational frequencies, corresponding vibrational assignments of 5-nitro-2-(4-nitrobenzyl) benzoxazole have been investigated experimentally and theoretically using Gaussian09 software package. Potential energy distribution of the normal modes of vibrations was done using GAR2PED program. The energy and oscillator strength calculated by time dependent density functional theory almost compliments with experimental findings. Gauge-including atomic orbital 1H NMR chemical shifts calculations were carried out by using B3LYP functional with 6-31G* basis set. The HOMO and LUMO analysis is used to determine the charge transfer within the molecule. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization have been analyzed using NBO analysis. MEP was performed by the DFT method and the predicted infrared intensities and Raman activities have also been reported. The calculated geometrical parameters are in agreement with that of similar derivatives.

Bhagyasree, J. B.; Varghese, Hema Tresa; Panicker, C. Yohannan; Samuel, Jadu; Van Alsenoy, Christian; Bolelli, Kayhan; Yildiz, Ilkay; Aki, Esin

2013-02-01

36

FT-IR, FT-Raman spectral and conformational studies on (E)-2-(2-hydroxybenzylidenamino)-3-(1H-indol-3yl) propionic acid.  

PubMed

The (E)-2-(2-hydroxybenzylidenamino)-3-(1H-indol-3yl) propionic acid ((E)-2HBA3IPA) was synthesized. The theoretical conformational analysis was performed to identify the stable structure. Optimized molecular bond parameters were calculated by using B3LYP/6-31G(d,p) basis set. The hyperconjugative interaction energy (E(2)) and electron densities of donor (i) and acceptor (j) bonds were calculated using NBO analysis. First order hyperpolarizability (?0) was calculated. The band gap energy was analyzed by UV-Visible recorded spectra and compared with theoretical band gap TD-DFT/B3LYP/6-31G(d,p) values. The intra-molecular hydrogen bonding interaction was identified between nitrogen and hydroxyl hydrogen (N?H-O). PMID:23099165

Saleem, H; Subashchandrabose, S; Erdogdu, Y; Thanikachalam, V; Jayabharathi, J

2012-09-16

37

Assembly of N,N-Disubstituted Hydrazines and 1-Aryl-1H-indazoles via Copper-Catalyzed Coupling Reactions.  

PubMed

CuI-catalyzed coupling of N-acyl-N'-substituted hydrazines with aryl iodides takes place at 60-90 °C to afford N-acyl-N',N'-disubstituted hydrazines regioselectively and thereby gives a facile method for assembling N,N-diaryl hydrazines. N-Acyl-N'-substituted hydrazines can also react with 2-bromoarylcarbonylic compounds at 60-125 °C under the catalysis of CuI/4-hydroxy-l-proline to provide 1-aryl-1H-indazoles. PMID:22545771

Xiong, Xiaodong; Jiang, Yongwen; Ma, Dawei

2012-04-30

38

FT-IR, UV-vis, 1H and 13C NMR spectra and the equilibrium structure of organic dye molecule disperse red 1 acrylate: a combined experimental and theoretical analysis.  

PubMed

This study reports the characterization of disperse red 1 acrylate compound by spectral techniques and quantum chemical calculations. The spectroscopic properties were analyzed by FT-IR, UV-vis, (1)H NMR and (13)C NMR techniques. FT-IR spectrum in solid state was recorded in the region 4000-400 cm(-1). The UV-vis absorption spectrum of the compound that dissolved in methanol was recorded in the range of 200-800 nm. The (1)H and (13)C NMR spectra were recorded in CDCl(3) solution. The structural and spectroscopic data of the molecule in the ground state were calculated using density functional theory (DFT) employing B3LYP exchange correlation and the 6-311++G(d,p) basis set. The vibrational wavenumbers were calculated and scaled values were compared with experimental FT-IR spectrum. A satisfactory consistency between the experimental and theoretical spectra was obtained and it shows that the hybrid DFT method is very useful in predicting accurate vibrational structure, especially for high-frequency region. The complete assignments were performed on the basis of the experimental results and total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method. Isotropic chemical shifts were calculated using the gauge-invariant atomic orbital (GIAO) method. A study on the electronic properties were performed by timedependent DFT (TD-DFT) and CIS(D) approach. To investigate non linear optical properties, the electric dipole moment ?, polarizability ?, anisotropy of polarizability ?? and molecular first hyperpolarizability ? were computed. The linear polarizabilities and first hyperpolarizabilities of the studied molecule indicate that the compound can be a good candidate of nonlinear optical materials. PMID:21958518

Cinar, Mehmet; Coruh, Ali; Karabacak, Mehmet

2011-09-09

39

Three Component Reaction: An Efficient Synthesis and Reactions of 3,4-Dihydropyrimidin-2(1H)-Ones and Thiones Using New Natural Catalyst.  

PubMed

Synthesis of 3,4-dihydropyrimidin-2(1H)-one and 3,4-dihydropyrimidin-2(1H)-thione derivatives from aldehydes, 1,3-dicarbonyl derivatives and urea or thiourea using granite and quartz as new, natural and reusable catalysts. Some of the 3,4-dihydropyrimidin-2(1H)-thione derivatives were used to prepare new heterocyclic compounds. The antimicrobial activity of selected examples of the synthesized compounds was tested and showed moderate activity. PMID:24052868

Elmaghraby, A M; Mousa, I A; Harb, A A; Mahgoub, M Y

2013-08-18

40

Mass of {sup 11}Li from the {sup 1}H({sup 11}Li,{sup 9}Li){sup 3}H reaction  

SciTech Connect

The mass of {sup 11}Li has been determined from Q-value measurements of the {sup 1}H({sup 11}Li,{sup 9}Li){sup 3}H reaction. The experiment was performed at TRIUMF laboratory with the GANIL active target MAYA. Energy-energy and angle-angle kinematics reconstruction give a Q value of 8.119(22) MeV for the reaction. The derived {sup 11}Li two-neutron separation energy is S{sub 2n}=363(22) keV.

Roger, T.; Savajols, H.; Mittig, W.; Caamano, M.; Roussel-Chomaz, P. [GANIL, Boulevard Henri Becquerel, Boite Postale 55027, F-14076 Caen Cedex 05 (France); Tanihata, I.; Alcorta, M.; Bandyopadhyay, D.; Bieri, R.; Buchmann, L.; Davids, B.; Galinski, N.; Howell, D.; Mills, W.; Mythili, S.; Openshaw, R.; Padilla-Rodal, E.; Ruprecht, G.; Sheffer, G.; Shotter, A. C. [TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3 (Canada)] (and others)

2009-03-15

41

Integrated HPLC-MS and (1)H-NMR spectroscopic studies on acyl migration reaction kinetics of model drug ester glucuronides.  

PubMed

Acyl glucuronides (AGs) are common, chemically reactive metabolites of acidic xenobiotics. Concerns about the potential of this class of conjugate to cause toxicity in man require efficient methods for the determination of reactivity, and this is commonly done by measuring transacylation kinetics. High-performance liquid chromatography-mass spectrometry (HPLC-MS) and nuclear magnetic resonance (NMR) spectroscopy were applied to the kinetic analysis of AG isomerization and hydrolysis for the 1-beta-O-AGs of ibufenac, (R)- and (S)-ibuprofen, and an alpha,alpha-dimethylated ibuprofen analogue. Each AG was incubated in either aqueous buffer at pH 7.4 or human plasma at 37 degrees C. Aliquots of these samples, taken throughout the reaction time course, were analysed by HPLC-MS and (1)H-NMR spectroscopy and the results compared. For identification of the AGs incubated in pH 7.4 buffer and for analysis of kinetic rates, (1)H-NMR spectroscopy generally gave the most complete set of data, but for human plasma the use of (1)H-NMR spectroscopy was impractical and HPLC-MS was more suitable. HPLC-MS was more sensitive than (1)H-NMR spectroscopy, but the lack of suitable stable-isotope labelled internal standards, together with differences in response between glucuronides and aglycones, made quantification problematic. Using HPLC-MS a specific 1-beta-O-AG-related ion at m/z 193 (the glucuronate fragment) was noted enabling selective determination of these isomers. In buffer, transacylation reactions predominated, with relatively little hydrolysis to the free aglycone observed. In human plasma incubations the observed rates of reaction were much faster than for buffer, and hydrolysis to the free aglycone was the major route. These results illustrate the strengths and weaknesses of each analytical approach for this class of analyte. PMID:19919325

Johnson, C H; Karlsson, E; Sarda, S; Iddon, L; Iqbal, M; Meng, X; Harding, J R; Stachulski, A V; Nicholson, J K; Wilson, I D; Lindon, J C

2010-01-01

42

Analyzing powers for the three-nucleon breakup reaction /sup 1/H(d vector,p)pn at 16 MeV  

SciTech Connect

Analyzing powers for the /sup 1/H(d,p)pn reaction were measured at 16.0 MeV and beam polarization of approximately 0.82. Similar data for the elastic scattering /sup 1/H(d,p)/sup 2/H were also taken. The breakup analyzing power A/sub xz/, which attains the largest magnitude, is shown as a function of excitation energy. Angular distributions of elastic and breakup analyzing powers are compared; large differences are noted for A/sub xx/ and A/sub xz/. It is found that 1-MeV energy bins are too large to use in the study of singlet-state effects. 2 figures. (RWR)

Brown, R.E.; Ohlsen, G.G.; Correll, F.D.; Hardekopf, R.A.; Jarmie, N.

1980-01-01

43

Effects which will not blur the message of the 1H (11Li, 9Li) 3H reaction: observation of phonon-exchange pairing correlations in nuclei  

NASA Astrophysics Data System (ADS)

The results of the 1H (11Li, 9Li) 3H experiment carried out recently at TRIUMF have given detailed information concerning the structure and the reaction mechanism at work in the case of halo, exotic nuclei, providing important stepping stones for an eventual quantitative description of superfluidity in finite nuclei. In fact, the central role played by renormalization processes as testified by the excitation of the 1/2- (2.69 MeV) member of the 9Li (2+ otimesp3/2(?))j- multiplet (nuclear structure) together with the post-prior symmetry (reaction), testify to the fact that a detailed knowledge of the "bare" quantities, like e.g. the NN-interaction is likely to be less important, in a unified Nuclear Field Theory description of the structure and the reaction aspects of the experiment, than previously thought.

Vigezzi, E.; Potel, G.; Barranco, F.; Broglia, R. A.

2011-09-01

44

Molecular structure, spectroscopic (FT-IR, FT-Raman, 13C and 1H NMR, UV), polarizability and first-order hyperpolarizability, HOMO and LUMO analysis of 4'-methylbiphenyl-2-carbonitrile.  

PubMed

In the present study, the molecular structure, vibrational and electronic transition, isotropic chemical shifts analysis of 4'-methylbiphenyl-2-carbonitrile were presented using experimental techniques (FT-IR, FT-Raman, NMR and UV) and quantum chemical calculations. FT-IR and FT-Raman spectra in solid state were observed in the region 4000-400cm(-1) and 3500-50cm(-1), respectively. The ultraviolet absorption spectrum of studied compound that dissolved in ethanol was examined in the range of 200-400nm. The (1)H and (13)C NMR spectra were recorded in DMSO solution. To determine lowest-energy molecular conformation of the title molecule, the selected torsion angle is varied every 10° and molecular energy profile is calculated from 0° to 360°. The molecular structure and spectroscopic data of the molecule in the ground state were computed by density functional theory (DFT) using 6-31++G(d,p) basis set. The complete assignments of all vibrational modes were performed on the basis of the total energy distributions (TED) of the vibrational modes, computed with scaled quantum mechanics (SQM) method. (13)C and (1)H isotropic chemical shifts were computed using the gauge-invariant atomic orbital (GIAO) method. Moreover, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energies, absorption wavelength were performed by time-dependent DFT approach. The dipole moment, linear polarizability and first hyperpolarizability values were also computed. The linear polarizabilities and first hyper polarizabilities of the studied molecule indicate that the compound is a good candidate of nonlinear optical materials. Comparison of the calculated frequencies, NMR chemical shifts, absorption wavelengths with the experimental values revealed that DFT method produces good results. PMID:22185952

Karabacak, Mehmet; Yilan, Erkan

2011-12-04

45

Design, synthesis, structural characterization by IR, (1) H, (13) C, (15) N, 2D-NMR, X-ray diffraction and evaluation of a new class of phenylaminoacetic acid benzylidene hydrazines as pfENR inhibitors.  

PubMed

Recent studies have revealed that plasmodial enoyl-ACP reductase (pfENR, FabI), one of the crucial enzymes in the plasmodial type II fatty acid synthesis II (FAS II) pathway, is a promising target for liver stage malaria infections. Hence, pfENR inhibitors have the potential to be used as causal malarial prophylactic agents. In this study, we report the design, synthesis, structural characterization and evaluation of a new class of pfENR inhibitors. The search for inhibitors began with a virtual screen of the iResearch database by molecular docking. Hits obtained from the virtual screen were ranked according to their Glide score. One hit was selected as a lead and modified to improve its binding to pfENR; from this, a series of phenylamino acetic acid benzylidene hydrazides were designed and synthesized. These molecules were thoroughly characterized by IR, (1) H, (13) C, (15) N, 2D-NMR (COSY, NOESY, (1) H-(13) C, (1) H-(15) N HSQC and HMBC), and X-ray diffraction. NMR studies revealed the existence of conformational/configurational isomers around the amide and imine functionalities. The major species in DMSO solution is the E, E form, which is in dynamic equilibrium with the Z, E isomer. In the solid state, the molecule has a completely extended conformation and forms helical structures that are stabilized by strong hydrogen bond interactions, forming a helical structure stabilized by N-H…O interactions, a feature unique to this class of compounds. Furthermore, detailed investigation of the NMR spectra indicated the presence of a minor impurity in most compounds. The structure of this impurity was deduced as an imidazoline-4-one derivative based on (1) H-(13) C and (1) H-(15) H HMBC spectra and was confirmed from the NOESY spectra. The molecules were screened for in vitro activity against recombinant pfENR enzyme by a spectrophotometric assay. Four molecules, viz. 17, 7, 10, and 12 were found to be active at 7, 8, 10, and 12 ?m concentration, respectively, showing promising pfENR inhibitory potential. A classification model was derived based on a binary QSAR approach termed recursive partitioning (RP) to highlight structural characteristics that could be tuned to improve activity. PMID:23398677

Samal, Ramanuj P; Khedkar, Vijay M; Pissurlenkar, Raghuvir R S; Bwalya, Angela Gono; Tasdemir, Deniz; Joshi, Ramesh A; Rajamohanan, P R; Puranik, Vedavati G; Coutinho, Evans C

2013-04-11

46

Longitudinal and Transverse Cross Sections in the {sup 1}H ({ital e},thinspthinsp {ital e}{sup {prime}}{ital K}{sup +}){Lambda} Reaction  

SciTech Connect

The {sup 1}H( e,thinspe{sup {prime}}K{sup +}){Lambda} reaction was studied as a function of the squared four-momentum transfer, Q{sup 2} , and the virtual photon polarization, {var_epsilon} . For each of four Q{sup 2} settings, 0.52, 0.75, 1.00, and 2.00 (GeV/c){sup 2} , the longitudinal and transverse virtual photon cross sections were extracted in measurements at three virtual photon polarizations. The Q{sup 2} dependence of the {sigma}{sub L}/{sigma}{sub T} ratio differs significantly from current theoretical predictions. This, combined with the precision of the measurement, implies a need for revision of existing calculations. {copyright} {ital 1998} {ital The American Physical Society }

Niculescu, G.; Gueye, P.; Ahmidouch, A.; Assamagan, K.; Avery, S.; Baker, O.K.; Beard, K.; Cha, J.; Eden, T.; Harvey, M.; Hinton, W.; Keppel, C.; Madey, R.; Niculescu, I.; Savage, G.; Tang, L.; Williams, R. [Hampton University, Hampton, Virginia 23668 (United States); Mohring, R.M.; Beise, E.; Breuer, H.; Chang, C.C.; Chant, N.; Collins, G.; Duncan, F.; Ewell, L.; Gustafsson, K.K.; Lung, A.; Roos, P. [University of Maryland, College Park, Maryland 20742 (United States); Abbott, D.; Baker, O.K.; Carlini, R.; Dunne, J.; Ent, R.; Keppel, C.; Mack, D.; Majewski, S.; Mitchell, J.; Tang, L.; Vulcan, W.; Wood, S.; Yan, C. [Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606 (United States); Ahmidouch, A.; Madey, R. [Kent State University, Kent, Ohio 44242 (United States); Amatuni, T.A.; Mkrtchyan, H.; Stepanyan, S.; Tadevosian, V. [Yerevan Physics Institute, Yerevan, (Armenia) 375306; Ambrozewicz, P.; Martoff, C.J. [Temple University, Philadelphia, Pennsylvania 19122 (United States); Angelescu, T.; Mihul, A.; Teodorescu, L. [Bucharest University, Bucharest, (Romania) R76900; Armstrong, C.S.; Finn, M.; Meekins, D. [College of William and Mary, Williamsburg, Virginia 23187 (United States); Bailey, K.; Cummings, W.; Geesaman, D.F.; Hansen, J.; Potterveld, D.; Reinhold, J.; Zeidman, B. [Argonne National Laboratory, Argonne, Illinois 60439 (United States); Beedoe, S.; Danagoulian, S.; Jackson, C.; Mtingwa, S.; Sawafta, R. [North Carolina A T State University, Greensboro, North Carolina 27411 (United States); Volmer, J. [Free University, Amsterdam, (The Netherlands) 1081; Cisbani, E.; De Leo, R.; Frullani, S.; Garibaldi, F.; Iodice, M.; Leone, T.; Lolos, G.; Perrino, R.; Urciuoli, G.M. [Physics Laboratory, Istituto Superiore di Sanita and INFN-Sezione Sanita, Rome, (Italy) I-00161; Dutta, D.; Segel, R. [Northwestern University, Evanston, Illinois 60201 (United States); Eyraud, L.; Furget, C.; Kox, S.; Real, J. [ISN, Grenoble, (France)

1998-08-01

47

Spectroscopic (IR, Raman, UV, 1H and 13C NMR) and microbiological studies of Fe(III), Ni(II), Cu(II), Zn(II) and Ag(I) picolinates  

NASA Astrophysics Data System (ADS)

The FT-IR, Raman spectra of picolinic acid as well as Fe(III), Zn(II), Cu(II), Ni(II) and Ag(I) picolinates were registered, assigned and compared. Some regularities in the spectra of studied picolinates within the regions: 1650 1340 cm-1 [?(CC)ar, ?as(COO-), ?s(COO-)]; 1300 1020 cm-1 [?(CH)]; 780 620 cm-1 [?(CH), ?(CCC)] were found. 1H and 13C NMR spectra for picolinic acid, Zn(II) and Ag(I) picolinates were recorded and studied as well. Moreover the UV spectra of picolinic and picolinates were registered and compared. The influence of Ag(I), Zn(II), Ni(II), Cu(II) and Fe(III) on the electronic system of picolinic acid was investigated. The microbiological activity of picolinates against two species of bacteria: Escherichia coli, Bacillus subtilis as well as two species of yeasts: Saccharomyces cerevisiae and Hansenula anomala was also studied.

Kalinowska, M.; Borawska, M.; ?wis?ocka, R.; Piekut, J.; Lewandowski, W.

2007-05-01

48

Molecular structures, FT-IR and FT-Raman spectra, NBO analysis, NLO properties, reactive sites and quantum chemical calculations of keto-enol tautomerism (2-amino-4-pyrimidinol and 2-amino-pyrimidine-4(1H)-one)  

NASA Astrophysics Data System (ADS)

The keto-enol tautomerism of 2-amino-4-pyrimidinol (APN) and 2-amino-pyrimidine-4(1H)-one (APO) are investigated by vibrational spectroscopy and quantum chemical method. FT-IR and FT-Raman spectra are recorded in the regions of 4000-400 cm-1 and 3500-100 cm-1, respectively for APN. Geometrical parameters, vibrational wavenumbers of APN and APO are predicted by density functional theory (DFT) employing B3LYP level with 6-311++G(d,p) and 6-311++G(2d,p) basis sets. The non-linear optical (NLO) properties of the title molecules are computed. The molecular electrostatic potential (MEP) surface maps are plotted and explained in detail. Natural bond orbital (NBO) analyses have been performed on APN molecule. The significant changes in occupancies and the energies of bonding and antibonding orbital have been explained in detail. Thermodynamic properties (heat capacities, entropies, and enthalpy) and their correlations with temperatures are also obtained from the calculated frequencies of the optimized structures. Reactivity descriptors, Fukui functions and electrophilic sites are found and discussed.

Balachandran, V.; Parimala, K.

2013-02-01

49

Molecular structures, FT-IR and FT-Raman spectra, NBO analysis, NLO properties, reactive sites and quantum chemical calculations of keto-enol tautomerism (2-amino-4-pyrimidinol and 2-amino-pyrimidine-4(1H)-one).  

PubMed

The keto-enol tautomerism of 2-amino-4-pyrimidinol (APN) and 2-amino-pyrimidine-4(1H)-one (APO) are investigated by vibrational spectroscopy and quantum chemical method. FT-IR and FT-Raman spectra are recorded in the regions of 4000-400 cm(-1) and 3500-100 cm(-1), respectively for APN. Geometrical parameters, vibrational wavenumbers of APN and APO are predicted by density functional theory (DFT) employing B3LYP level with 6-311++G(d,p) and 6-311++G(2d,p) basis sets. The non-linear optical (NLO) properties of the title molecules are computed. The molecular electrostatic potential (MEP) surface maps are plotted and explained in detail. Natural bond orbital (NBO) analyses have been performed on APN molecule. The significant changes in occupancies and the energies of bonding and antibonding orbital have been explained in detail. Thermodynamic properties (heat capacities, entropies, and enthalpy) and their correlations with temperatures are also obtained from the calculated frequencies of the optimized structures. Reactivity descriptors, Fukui functions and electrophilic sites are found and discussed. PMID:23220518

Balachandran, V; Parimala, K

2012-10-22

50

Unusual 1H NMR chemical shifts support (His) C1---H···O==C H-bond: Proposal for reaction-driven ring flip mechanism in serine protease catalysis  

Microsoft Academic Search

13C-selective NMR, combined with inhibitor perturbation experiments, shows that the C1---H proton of the catalytic histidine in resting -lytic protease and subtilisin BPN' resonates, when protonated, at 9.22 ppm and 9.18 ppm, respectively, which is outside the normal range for such protons and 0.6 to 0.8 ppm further downfield than previously reported. They also show that the previous -lytic protease

Elissa L. Ash; James L. Sudmeier; Regina M. Day; Matthew Vincent; Ekaterina V. Torchilin; Kristin Coffman Haddad; Elizabeth M. Bradshaw; David G. Sanford; William W. Bachovchin

2000-01-01

51

The adsorption and reaction of normal alkanes on the Ir(110)-(1 × 2) surface  

NASA Astrophysics Data System (ADS)

Previous studies of the adsorption and reaction of ethane and propane on the Ir(110)-(1 × 2) surface have been extended to the normal isomers of butane, pentane, hexane and heptane. At low coverages, each of these alkanes undergoes dissociative chemisorption at 125 130 K. At higher coverages, molecular adsorption occurs as well. Thermal desorption spectra of hydrogen are similar in many respects for the dissociative adsorption of all six of these paraffins, and both desorption-limited and reaction-limited adstates are observed. The latter are associated with the dehydrogenation of hydrocarbon fragments on the surface. Ethane, butane and hexane form high temperature adstates, the associated fragments of which are low in hydrogen content, while those for propane, pentane and heptane contain relatively more hydrogen. This difference may be explained in terms of a model for dehydrogenation which has been proposed previously [T.S. Wittrig, P.D. Szuromi and W.H. Weinberg, J. Chem. Phys. 76, (1982) 3305] in understanding the reaction of other hydrocarbons on this surface.

Szuromi, P. D.; Weinberg, W. H.

1985-01-01

52

Calcium fluoride: an efficient and reusable catalyst for the synthesis of 3,4-dihydropyrimidin-2(1 H)-ones and their corresponding 2(1 H)thione: an improved high yielding protocol for the Biginelli reaction  

Microsoft Academic Search

A simple and effective synthesis of 3,4-dihydropyrimidinone derivatives from aldehydes, 1,3-dicarbonyl compounds, and urea\\/thiourea in ethanol by using calcium fluoride as catalyst has been described. Compared with classical Biginelli reaction conditions, this new method has the advantage of excellent yields and shorter reaction times. Also, the catalyst can be reused without any reduction in efficiency.

S. Chitra; K. Pandiarajan

2009-01-01

53

Comparative IR spectroscopic study of Pt- and Pd-containing zeolites in the hydrodechlorination reaction of carbon tetrachloride  

NASA Astrophysics Data System (ADS)

Hydrodechlorination of CCl4 was investigated on noble metal containing zeolite catalysts by IR spectroscopy. Both the surface species and the gas phase reaction products were simultaneously analysed. Results revealed that the reaction rate and the reaction products were different on Pt- and Pd-containing samples. The enhanced formation of ethane and the suppressed generation of methane over Pd/NaY-FAU zeolite and the formation of chloroform as intermediate product over Pt/NaY-FAU zeolite were explained by the different bond strength of reaction intermediates to the metal surface. The influence of acid sites on the product distribution was traced back to the local decomposition of zeolite framework. A combination of IR spectroscopic methods including simultaneous analysis of gas phase products and surface intermediates proved to be an excellent tool for investigating the reaction mechanism.

Imre, Béla; Hannus, István; Kiricsi, Imre

2005-06-01

54

Platinum-monolayer Electrocatalysts: Palladium Interlayer on IrCo Alloy Core Improves Activity in Oxygen-reduction Reaction  

SciTech Connect

We describe the synthesis and electrocatalytic properties of a new low-Pt electrocatalyst consisting of an IrCo core, a Pd interlayer, and a surface Pt monolayer, emphasizing the interlayer's role in improving electrocatalytic activity for the oxygen-reduction reaction on Pt in HClO{sub 4} solution. We prepared the IrCo alloys by decomposing, at 800 C, hexacyanometalate, KCoIr(CN){sub 6}, adsorbed on the carbon surfaces. The synthesis of Ir{sub 3}Co/C involved heating a mix of metal salts and carbon in hydrogen at 500 C. Thereafter, we placed a palladium and/or platinum monolayer on them via the galvanic displacement of an underpotentially deposited copper monolayer. The electrocatalysts were characterized using structural- and electrochemical-techniques. For PtML/PdML/IrCo/C, we observed a Pt mass activity of 1.18 A/mg{sub (Pt)} and the platinum-group-metals mass of 0.16 A/mg{sub (Pt, Pd, Ir)}. In comparison, without a Pd interlayer, i.e., Pt{sub ML}/IrCo/C, the activities of 0.15 A/mg{sub (Pt)} and 0.036 A/mg{sub (Pt, Pd, Ir)} were considerably lower. We consider that the palladium interlayer plays an essential role in achieving high catalytic activity by adjusting the electronic interaction of the platinum monolayer with the IrCo core, so that it accelerates the kinetics of adsorption and desorption of the intermediates of oxygen reduction. A similar trend was observed for Pt{sub ML}/Pd{sub ML} and Pt{sub ML} deposited on Ir{sub 3}Co/C alloy core. We used density functional theory to interpret the observed phenomena.

Gong, K.; Chen, W.-F.; Sasaki, K.; Su, D.; Vukmirovic, M.B.; Zhou, W.; Izzo, E.L.; Perez-Acosta, C.; Hirunsit, P.; Balbuena, P.B.; Adzic, R.R.

2010-11-15

55

Platinum Monolayer on IrFe CoreâShell Nanoparticle Electrocatalysts for the Oxygen Reduction Reaction  

Microsoft Academic Search

We synthesized high activity and stability platinum monolayer on IrFe core-shell nanoparticle electrocatalysts. Carbon-supported IrFe core-shell nanoparticles were synthesized by chemical reduction and subsequent thermal annealing. The formation of Ir shells on IrFe solid-solution alloy cores has been verified by scanning transmission electron microscopy coupled with energy-loss spectroscopy (EELS) and in situ X-ray absorption spectroscopy. The Pt monolayers were deposited

Sasaki K; K. A. Kuttiyiel; D. Su; R. R. Adzic

2012-01-01

56

High accuracy measurements of OH reaction rate constants and IR absorption spectra: substituted 2-propanols.  

PubMed

Rate constants for the gas phase reactions of OH radicals with 2-propanol and three fluorine substituted 2-propanols, (CH(3))(2)CHOH (k(0)), (CF(3))(2)CHOH (k(1)), (CF(3))(2)C(OH)CH(3) (k(2)), and (CF(3))(3)COH (k(3)), were measured using a flash photolysis resonance-fluorescence technique over the temperature range 220-370 K. The Arrhenius plots were found to exhibit noticeable curvature for all four reactions. The temperature dependences of the rate constants can be represented by the following expressions: k(0)(T) = 1.46 × 10(-11) exp{-883/T} + 1.30 × 10(-12) exp{+371/T} cm(3) molecule(-1) s(-1); k(1)(T) = 1.19 × 10(-12) exp{-1207/T} + 7.85 × 10(-16) exp{+502/T } cm(3) molecule(-1) s(-1); k(2)(T) = 1.68 × 10(-12) exp{-1718/T} + 7.32 × 10(-16) exp{+371/T} cm(3) molecule(-1) s(-1); k(3)(T) = 3.0 × 10(-20) × (T/298)(11.3) exp{+3060/T} cm(3) molecule(-1) s(-1). The atmospheric lifetimes due to reactions with tropospheric OH were estimated to be 2.4 days and 1.9, 6.3, and 46 years, respectively. UV absorption cross sections were measured between 160 and 200 nm. The IR absorption cross sections of the three fluorinated compounds were measured between 450 and 1900 cm(-1), and their global warming potentials were estimated. PMID:22372969

Orkin, Vladimir L; Khamaganov, Victor G; Kurylo, Michael J

2012-04-02

57

Analyzing powers for the {sup 2}H({ital {rvec p}},{ital pn}){sup 1}H reaction at 200 MeV  

SciTech Connect

We measured the analyzing power {ital A}{sub {ital y}} and the triple differential cross section {ital d}{sup 3}{sigma}/{ital d}{Omega}{sub {ital pd}}{Omega}{sub {ital ndE}}{sub {ital p}} for the {sup 2}H({ital {rvec p}},{ital pn}){sup 1}H reaction at 200 MeV. Coplanar coincidence data were taken for all combinations of neutron angles {theta}{sub {ital n}}=35{degree}, 45{degree}, or 55{degree} with proton angles {theta}{sub {ital p}}=35{degree}, 45{degree}, or 52{degree}. Protons were detected with a {Delta}{ital E}-{ital E} telescope with a 1000-{mu}m silicon surface barrier {Delta}{ital E} detector and a plastic scintillator {ital E} detector. Neutrons were detected with large-volume plastic scintillators at flight paths of 17.5 or 18 m. The overall neutron separation-energy resolution was about 3 MeV. Data are compared with plane-wave impulse-approximation calculations with a Hulthen deuteron wave function and {ital p}-{ital n} cross sections and analyzing powers obtained from {ital N}-{ital N} phase shifts. The agreement between these calculations and the data is generally good for the cross sections. The agreement for the analyzing powers is good near the point of zero recoil momentum. Our results suggest that the deuteron is a good ``neutron target`` for recoil momenta {lt}100 MeV/{ital c}.

Pairsuwan, W.; Watson, J.W.; Ahmad, M.; Chant, N.S.; Flanders, B.S.; Madey, R.; Pella, P.J.; Roos, P.G. [Department of Physics, Kent State University, Kent, Ohio 44242 (United States)]|[Department of Physics and Astronomy, University of Maryland, College Park, Maryland 20742 (United States)]|[Department of Physics, Gettysburg College, Gettysburg, Pennsylvania 17325 (United States)

1995-11-01

58

REACTION OF SCHIFF'S BASES WITH MERCAPTO ACIDS. SYNTHESIS OF SPIRO [2H-1,3-BENZOTHIAZINE-2,3?-[3H]INDOLE]-2?,4(1?H,3H)-DIONES AND SPIRO[3H-INDOLE-3,2?THIAZOLIDINE]-2,4?(1H)-DIONES  

Microsoft Academic Search

The synthesis of some new sulfur containing spiroindole derivatives is reported. Spiro[2H-1,3-benzothiazine-2,3?-[3H]indole]-2?,4(1?H,3H)-diones and spiro[3H-indole-3,2?-thiazolidine]-2,4?(1H)-diones were prepared by the reaction of 3-[2-(4-arylthiazolylimino)]-1,3-dihydro-2H-indol-2-one with o-mer-captobenzoic acid and mercaptoacetic acid respectively. Such spiro benzothiazineindoles are being reported for the first time. The compounds have been characterised on the basis of elemental and spectral studies.

Renuka Jain; Shipra Vajpei

1992-01-01

59

Platinum Monolayer on IrFe Core–Shell Nanoparticle Electrocatalysts for the Oxygen Reduction Reaction  

SciTech Connect

We synthesized high activity and stability platinum monolayer on IrFe core-shell nanoparticle electrocatalysts. Carbon-supported IrFe core-shell nanoparticles were synthesized by chemical reduction and subsequent thermal annealing. The formation of Ir shells on IrFe solid-solution alloy cores has been verified by scanning transmission electron microscopy coupled with energy-loss spectroscopy (EELS) and in situ X-ray absorption spectroscopy. The Pt monolayers were deposited on IrFe core-shell nanoparticles by galvanic replacement of underpotentially deposited Cu adatoms on the Ir shell surfaces. The specific and Pt mass activities for the ORR on the Pt monolayer on IrFe core-shell nanoparticle electrocatalyst are 0.46 mA/cm{sup 2} and 1.1 A/mg{sub Pt}, which are much higher than those on a commercial Pt/C electrocatalyst. High durability of Pt{sub ML}/IrFe/C has also been demonstrated by potential cycling tests. These high activity and durability observed can be ascribed to the structural and electronic interaction between the Pt monolayer and the IrFe core-shell nanoparticles.

Sasaki K.; Kuttiyiel, K.A.; Su, D.; Adzic, R.R.

2012-04-19

60

Platinum Monolayer on IrFe Core-Shell Nanoparticle Electrocatalysts for the Oxygen Reduction Reaction  

SciTech Connect

We synthesized high activity and stability platinum monolayer on IrFe core-shell nanoparticle electrocatalysts. Carbon-supported IrFe core-shell nanoparticles were synthesized by chemical reduction and subsequent thermal annealing. The formation of Ir shells on IrFe solid-solution alloy cores has been verified by scanning transmission electron microscopy coupled with energy-loss spectroscopy (EELS) and in situ X-ray absorption spectroscopy. The Pt monolayers were deposited on IrFe core-shell nanoparticles by galvanic replacement of underpotentially deposited Cu adatoms on the Ir shell surfaces. The specific and Pt mass activities for the ORR on the Pt monolayer on IrFe core-shell nanoparticle electrocatalyst are 0.46 mA/cm{sup 2} and 1.1 A/mg{sub Pt}, which are much higher than those on a commercial Pt/C electrocatalyst. High durability of Pt{sub ML}/IrFe/C has also been demonstrated by potential cycling tests. These high activity and durability observed can be ascribed to the structural and electronic interaction between the Pt monolayer and the IrFe core-shell nanoparticles.

K Sasaki; K Kuttiyiel; D Su; R Adzic

2011-12-31

61

Platinum Monolayer on IrFe Core–Shell Nanoparticle Electrocatalysts for the Oxygen Reduction Reaction  

Microsoft Academic Search

We synthesized high activity and stability platinum monolayer on IrFe core–shell nanoparticle electrocatalysts. Carbon-supported\\u000a IrFe core–shell nanoparticles were synthesized by chemical reduction and subsequent thermal annealing. The formation of Ir\\u000a shells on IrFe solid-solution alloy cores has been verified by scanning transmission electron microscopy coupled with energy-loss\\u000a spectroscopy (EELS) and in situ X-ray absorption spectroscopy. The Pt monolayers were deposited

Kotaro Sasaki; Kurian A. Kuttiyiel; Dong Su; Radoslav R. Adzic

2011-01-01

62

[FT-IR study on the solid-state reaction of bilirubin on BaF2].  

PubMed

Bilirubinate complexes are the main component of pigment gallstones and the recent researches suggested that bilirubin free radical plays a role in some biological processes. In this paper the solid-state reaction of bilirubin on BaF2 was examined by FT-IR. The solid-state reaction was produced by grinding the crystalline bilirubin and single crystals BaF2 together in an agate mortar. From the results the free radical mechanism is suggested in the solid-state reaction of bilirubin on BaF2. The replacement of H on NH of pyrrole by Ba2+ was prior to that of H on COOH. The structure of the resultant complex from the solid-state reaction is different compared with that from the liquid-state reaction. PMID:15810303

Yang, Z; Weng, S; Wu, J

1998-04-01

63

One-pot three component condensation reaction in water: an efficient and improved procedure for the synthesis of furo[2,3- d]pyrimidine-2,4(1 H,3 H)-diones  

Microsoft Academic Search

The environment-friendly three component condensation reactions of N,N?-dimethylbarbituric acid, 4-nitrobenzaldehyde and alkyl or aryl isocyanides to afford the corresponding furo[2,3-d]pyrimidine-2,4(1H,3H)-diones, in water, in high yields after several minutes are reported.

Ahmad Shaabani; Mohammad Bagher Teimouri; Hamid Reza Bijanzadeh

2002-01-01

64

Model calculations of (sup 111)In production via the (sup 112,114,115,116,117)Sn((sup 1)H, xnypz(alpha))(sup 111)Sb (yields) (sup 111)Sn (yields) (sup 111)In reactions.  

National Technical Information Service (NTIS)

The possibility of production of no-carrier-added (sup 111)In from its grandparent (sup 111)Sb via (sup 112,114,115,116,117)Sn ((sup 1)H,xn) (sup 111)Sb (yields) (sup 111)Sb (yields) (sup 111)Sn (yields) (sup 111)In reactions and from its parent (sup 111)...

E. Rurarz S. Mikolajewski

1993-01-01

65

Diels-Alder reactions of 5,6-dihydro-2(1 H)-pyridones. Preparation of partially reduced cis-isoquinolones and cis-3,4-disubstituted piperidines  

Microsoft Academic Search

The Diels-Alder reactions of 5,6-dihydro-2(1H)-pyridones with a variety of diversely substituted butadienes to give partially reduced isoquinolones is reported. Reductive ozonolysis of the resulting octahydroisoquinolones gave cis-3,4-disubstituted piperidines.

Núria Casamitjana; Angela Jorge; Carles G. Pérez; Joan Bosch; Enric Espinosa; Elies Molins

1997-01-01

66

Reactions of chloride salts of 7-amino-9-ethylguanine and 1-amino-3-methylbenzimidazoles with lead(IV) acetate: Formation of 8-aza-9-ethylguanine and 1-methyl-1 H-benzotriazoles  

Microsoft Academic Search

Reaction of 7-amino-9-ethylguaninium chloride with lead(IV) acetate (LTA) in MeOH yielded 8-aza-9-ethylguanine. Similarly, the reaction of 1-amino-3-methylbenzimidazolium chloride or its substituted derivatives (6-methyl, 5,6-dimethyl and 5-nitro) with LTA gave the corresponding 1-methyl-1H-benzotriazole (or 1-methyl-2-azabenzimidazole) derivatives along with N-methylformanilide derivatives.

Toyo Kaiya; Shinsuke Aoyama; Kohfuku Kohda

1999-01-01

67

Reactions of chloride salts of 7-amino-9-ethylguanine and 1-amino-3-methylbenzimidazoles with lead(IV) acetate: formation of 8-aza-9-ethylguanine and 1-methyl-1H-benzotriazoles.  

PubMed

Reaction of 7-amino-9-ethylguaninium chloride with lead(IV) acetate (LTA) in MeOH yielded 8-aza-9-ethylguanine. Similarly, the reaction of 1-amino-3-methylbenzimidazolium chloride or its substituted derivatives (6-methyl, 5,6-dimethyl and 5-nitro) with LTA gave the corresponding 1-methyl-1H-benzotriazole (or 1-methyl-2-azabenzimidazole) derivatives along with N-methylformananilide derivatives. PMID:10230620

Kaiya, T; Aoyama, S; Kohda, K

1999-04-01

68

Oxygen evolution reaction on IrO 2-based DSA ® type electrodes: kinetics analysis of Tafel lines and EIS  

Microsoft Academic Search

The oxygen evolution reaction (OER) on IrO2–Ta2O5 mixed oxide electrodes in H2SO4 solution was studied by performing quasi-stationary current-potential and electrochemical impedance spectroscopy (EIS) measurements. The uncompensated resistance corrected Tafel lines displayed two distinct linear regions, with one of the slope close to 60mVdec?1 in the low potential region and the other close to 130mVdec?1 in the high potential region.

Ji-Ming Hu; Jian-Qing Zhang; Chu-Nan Cao

2004-01-01

69

In situ FT-IR study on the reaction path of skeletal isomerization of n-butene over different zeolites  

Microsoft Academic Search

Adsorption and reaction of 1-butene, cis- and trans-2-butene and isobutene on H-ZSM-5 and H-FER were studied by FT-IR spectroscopy between 30–450°C. n-Butenes were monomolecularly adsorbed via ?-bonding on H-FER at 30°C. At elevated temperatures butadiene was monitored on H-FER, which was then transformed into dialkyldiphenyl. On H-ZSM-5 all butene isomers were adsorbed via ?-bonds, followed by dimerization. From these results

P. Ivanov; H. Papp

2001-01-01

70

The chemistry of indoles. CVII. A novel synthesis of 3,4,5,6-tetrahydro-7-hydroxy-1H-azepino[5,4,3-cd]indoles and a new finding on Pictet-Spengler reaction.  

PubMed

Serotonins were found to produce 3,4,5,6-tetrahydro-7-hydroxy-1H-azepino[5,4,3-cd]indoles by simple heating with amines under an oxygen atmosphere. Serotonins also reacted with various aldehydes to provide 3,4,5,6-tetrahydro-7-hydroxy-1H-azepino[5,4,3-cd]indoles rather than beta-carbolines under basic conditions. In these novel reactions, the presence of the 5-hydroxy group on the indole nucleus was suggested to be essential. Possible mechanisms are discussed. PMID:11558603

Somei, M; Teranishi, S; Yamada, K; Yamada, F

2001-09-01

71

Infrared spectra of XC[triple bond]IrX(3) and CX(2)=IrX(2) prepared by reactions of laser-ablated iridium atoms with halomethanes.  

PubMed

Small iridium high oxidation-state complexes with carbon-iridium multiple bonds are identified in the product matrix infrared spectra from reactions of laser-ablated Ir atoms with tetra-, tri- and dihalomethanes. In contrast to the previously studied Rh case, Ir carbyne complexes (XC[triple bond]IrX(3)) are generated in reactions of tetrahalomethanes, and their short Ir-C bond lengths of 1.725-1.736 A are appropriate for the carbon-metal triple bonds. DFT calculations also show that the Ir carbynes with an Ir-F bond have unusual square planar structures, similar to the recently discovered Ru planar complexes. Diminishing preference for the carbyne complexes leads to methylidene product absorptions in the tri- and dihalomethane spectra, marking a limit for generation of small metal carbynes. The insertion complexes, on the other hand, are not observed in this study, suggesting that X migration from C to Ir following initial C-X insertion is swift. PMID:20442951

Cho, Han-Gook; Andrews, Lester

2010-05-05

72

Reaction between enaminones and acetylenic esters in the presence of triphenylphosphine: a convenient synthesis of alkyl 2(1-benzyl-2,4-dioxo-2,3,4,5,6,7-hexahydro-1H-indol-3-yl)acetates.  

PubMed

One-pot reaction between enaminocarbonyl compounds derived from six-membered 1,3-diketones and substituted benzylamines, and electron-deficient acetylenic esters in the presence of triphenylphosphine lead to alkyl 2-(1-benzyl-6,6-dimethyl-2,4-dioxo-2,3,4,5,6,7-hexahydro-1H-indol-3-yl)acetate derivatives in good yields. PMID:22926458

Nasiri, Farough; Bayzidi, Massood; Zolali, Amin

2012-08-25

73

Synthesis of densely functionalized 3a,4-dihydro-1H-pyrrolo[1,2-b]pyrazoles via base mediated domino reaction of vinyl malononitriles with 1,2-diaza-1,3-dienes.  

PubMed

A domino reaction of vinyl malononitriles (VMs) with 1,2-diaza-1,3-dienes (DDs) produce unprecedented 3a,4-dihydro-1H-pyrrolo[1,2-b]pyrazole systems in a chemo-, regio-, and stereoselective fashion. This base promoted (DIPEA) one-pot transformation involving multiple steps constructs one new C-C bond, two C-N bonds, and two new fused heterocyclic rings with total atom economy. PMID:23683051

Attanasi, Orazio A; Favi, Gianfranco; Geronikaki, Athina; Mantellini, Fabio; Moscatelli, Giada; Paparisva, Aliki

2013-05-17

74

In situ FT-IR study on the reaction path of skeletal isomerization of n-butene over different zeolites  

NASA Astrophysics Data System (ADS)

Adsorption and reaction of 1-butene, cis- and trans-2-butene and isobutene on H-ZSM-5 and H-FER were studied by FT-IR spectroscopy between 30-450°C. n-Butenes were monomolecularly adsorbed via ?-bonding on H-FER at 30°C. At elevated temperatures butadiene was monitored on H-FER, which was then transformed into dialkyldiphenyl. On H-ZSM-5 all butene isomers were adsorbed via ?-bonds, followed by dimerization. From these results and from catalytic measurements a monomolecular pathway is proposed on H-FER and a bimolecular one on H-ZSM-5.

Ivanov, P.; Papp, H.

2001-07-01

75

Reaction properties of NO and CO over an Ir(211) surface  

SciTech Connect

The adsorption and thermal reactivity of NO and CO over an Ir(211) surface were studied using x-ray photoelectron spectroscopy, infrared reflection absorption spectroscopy, and temperature-programed desorption. NO adsorbed on the atop site of the (111) terrace and the bridge site of the (100) step at 273 K. In contrast, CO adsorbed only on the atop site at 273 K, initially on the (111) terrace and then on the (100) step. Both atop NO and bridge NO decomposed to N{sub 2} through the recombination of atomic nitrogen, indicating that the Ir(211) surface provides high NO dissociation activity. When NO and CO were coadsorbed, the preadsorption of atop CO on the terrace sites selectively inhibited the adsorption of atop NO on the terrace sites, while preadsorption of atop CO on the step sites significantly inhibited the adsorption of bridge NO on the step sites. These results indicate that NO may be selectively reduced by CO in the presence of O{sub 2} when Ir(211) is used as the catalyst.

Nakamura, I.; Suzuki, K.; Takahashi, A.; Haneda, M.; Hamada, H.; Fujitani, T. [Research Institute for Innovation in Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569 (Japan)

2007-07-15

76

Bimetallic IrNi Core Platinum Monolayer Shell Electrocatalysts for the Oxygen Reduction Reaction  

SciTech Connect

We synthesized a low-Pt content electrocatalyst consisting of a Pt monolayer placed on carbon-supported thermally treated IrNi core-shell structured nanoparticles using galvanic displacement of a Cu monolayer deposited at underpotentials. The Pt mass activity of the Pt{sub ML}/IrNi/C electrocatalyst obtained in a scale-up synthesis is approximately 3 times higher than that of the commercial Pt/C electrocatalyst. The electronic and geometrical effects of the IrNi substrate on the Pt monolayer result in its higher catalytic activity than that of Pt nanoparticles. The structure and composition of the core-shell nanoparticles were verified using transmission electron microscopy and in situ X-ray absorption spectroscopy, while a potential cycling test was employed to confirm the stability of the electrocatalyst. Our experimental results, supported by the density functional calculations using a sphere-like model, demonstrate an effective way of using Pt that can resolve key problems of cathodic oxygen reduction hampering fuel cell commercialization.

Kuttiyiel K. A.; Sasaki, K.; Choi, Y.M.; Su, D.; Liu, P.; Adzic, R.R.

2012-01-01

77

2D NMR studies of aminoglycoside antibiotics. Use of relayed coherence transfer for /sub 1/H resonance assignment and in situ structure elucidation of amikacin derivatives in reaction mixtures  

SciTech Connect

Phase-sensitive 2D /sup 1/H//sup 1/H COSY spectra can be used to identify the structures of individual pure specimens of the aminoglycoside antibiotic amikacin and its N-hemisuccinyl derivatives. However, even at 500 MHz the 2D chemical shift dispersion does not allow for unambiguous assignment of all cross-peaks. By use of 2D relayed coherence transfer experiments (RELAY) optimized to detect two-step /sup 1/H//sup 1/H scalar interactions in which one of the J-values is small, sufficient additional correlations can be obtained from the frequency-isolated resonances to allow facile tracing of all scalar connectivities. Complete assignments of the /sup 1/H NMR spectra of amikacin, its 6'-N-hemisuccinamide, and a novel bis(acylate) (..gamma..-N-(p-vinylbenzoyl)amikacin 6'-N-hemisuccinamide) were obtained for aqueous media. The NMR spectrum of amikacin free base was also assigned in dimethyl sulfoxide solution. The RELAY experiment can be extended to the analysis of reaction mixtures, which allows for the identification and resonance assignment of regioisomeric amikacin haptens in the mixture state. All of the N-monohemisuccinyl isomers of amikacin have been identified in reaction mixtures through the RELAY experiment. The relative reactivities of the amino functions of amikacin toward acylating agents were found to be 6'-N > 3-N greater than or equal to 3''-N greater than or equal to ..gamma..-N. However, this reactivity order is altered after the initial acylation event.

Andersen, N.H.; Eaton, H.L.; Nguyen, K.T.; Hartzell, C.; Nelson, R.J.; Priest, J.H.

1988-04-19

78

Investigation of Raman, FT-IR, EPR spectra and antimicrobial activity of 2-(5-H\\/Me\\/Cl1 H -benzimidazol-2-yl)-phenol ligands and their Fe(NO 3 ) 3 complexes  

Microsoft Academic Search

2-(5-H\\/Me\\/Cl-1H-benzimidazol-2-yl)-phenol ligands form 1:1 electrolytes, 5-coordinate monometallic complexes with iron(III) nitrate. The geometry of the [Fe(L)(OH)(H2O)2](NO3) complexes was derived from theoretical calculation in DGauss\\/DFT level (DZVP basis set) on CACHE. In all of the complexes\\u000a the ligands are bidentate, via one imine nitrogen atom and phenolate oxygen atom. The coordination is completed with a hydroxide ion, and two water molecules,

Aydin Tavman; Naz M. Agh-Atabay; Sadik Guner; Fahrettin Gucin; Basaran Dulger

2007-01-01

79

FT-IR and theoretical study of 3,5-dimethyl-1 H-pyrazole-1-carboxamidine (L) and the complexes CoL 2(H 2O) 2(NO 3) 2, NiL 2(H 2O) 2(NO 3) 2  

NASA Astrophysics Data System (ADS)

In the paper a joint experimental and theoretical study of 3,5-dimethyl-1 H-pyrazole-1-carboxamidine (L) as well as its complexes CoL 2(H 2O) 2(NO 3) 2 and NiL 2(H 2O) 2(NO 3) 2 is reported. On the basis of FT-IR experiments and a DFT-derived scaled quantum mechanical force field the normal coordinate analysis of L was carried out. The FT-IR spectra of the two complexes were interpreted using the present assignment of L and computed vibrational data of the complexes. The ionic and charge transfer interactions in the complexes were assessed by means of natural bond orbital (NBO) analysis.

Pogány, Peter; Kovács, Attila; Szécsényi, Katalin Mészáros; Leovac, Vukadin M.

2008-12-01

80

Synthesis, spectroscopic (FT-IR, FT-Raman, 13C, 1H, UV) study, first order hyperpolarizability, NBO analysis, HOMO and LUMO analysis of 2(2-Hydroxyphenyl)-N-(4-Methylphenyl) Nitrone  

NASA Astrophysics Data System (ADS)

The title compound, 2(2-Hydroxyphenyl)-N-(4-Methylphenyl) Nitrone (2HPN4MPN) was synthesized and characterized by FT-IR, FT-Raman, UV-Vis and 1HNMR, 13CNMR spectral analysis. The molecular geometry, harmonic vibrational frequencies and bonding features of the title compound in the ground state are computed at three parameter hybrid functional Lee-Yang-Parr/6-311++G(d,p) levels of theory. The most stable conformer of 2HPN4MPN is identified from the computational results. The assignments of the vibrational spectra have been carried out with the help of normal co-ordinate analysis (NCA) following the scaled quantum mechanical force field methodology (SQMF). The UV-Vis spectrum was recorded in chloroform solution. The energy and oscillator strength calculated by time-dependent density functional theory (TD-DFT) complements the experimental findings. The calculated HOMO and LUMO energies confirm that charge transfer occurs within the molecule. In addition, DFT calculations of the compound, Molecular Electrostatic Potential (MEP), Natural Bond Orbital analysis (NBO) and non-linear optical (NLO) properties are performed at B3LYP/6-311++G(d,p) level of theory. Finally, the calculations are applied to simulated FT-IR and FT-Raman spectra of the title compound which show good agreement with observed spectra.

Sheela, N. R.; Sampathkrishnan, S.; Thirumalai Kumar, M.; Muthu, S.

2013-05-01

81

Product screening of fast reactions in IR-laser-heated liquid water filaments in a vacuum by mass spectrometry.  

PubMed

In the present article a novel approach for rapid product screening of fast reactions in IR-laser-heated liquid microbeams in a vacuum is highlighted. From absorbed energies, a shock wave analysis, high-speed laser stroboscopy, and thermodynamic data of high-temperature water the enthalpy, temperature, density, pressure, and the reaction time window for the hot water filament could be characterized. The experimental conditions (30 kbar, 1750 K, density approximately 1 g/cm3) present during the lifetime of the filament (20-30 ns) were extreme and provided a unique environment for high-temperature water chemistry. For the probe of the reaction products liquid beam desorption mass spectrometry was employed. A decisive feature of the technique is that ionic species, as well as neutral products and intermediates may be detected (neutrals as protonated aggregates) via time-of-flight mass spectrometry without any additional ionization laser. After the explosive disintegration of the superheated beam, high-temperature water reactions are efficiently quenched via expansion and evaporative cooling. For first exploratory experiments for chemistry in ultrahigh-temperature, -pressure and -density water, we have chosen resorcinol as a benchmark system, simple enough and well studied in high-temperature water environments much below 1000 K. Contrary to oxidation reactions usually present under less extreme and dense supercritical conditions, we have observed hydration and little H-atom abstraction during the narrow time window of the experiment. Small amounts of radicals but no ionic intermediates other than simple proton adducts were detected. The experimental findings are discussed in terms of the energetic and dense environment and the small time window for reaction, and they provide firm evidence for additional thermal reaction channels in extreme molecular environments. PMID:16509656

Charvat, A; Stasicki, B; Abel, B

2006-03-01

82

Copper(II)-catalyzed asymmetric henry reaction of o-alkynylbenzaldehydes followed by gold(I)-mediated cycloisomerization: an enantioselective route to chiral 1H-isochromenes and 1,3-dihydroisobenzofurans.  

PubMed

By combining the copper(II)-catalyzed asymmetric Henry reaction of o-alkynylbenzaldehydes with subsequent gold(I)-catalyzed cycloisomerization, optically active 1H-isochromenes and 1,3-dihydroisobenzofurans were successfully synthesized in good overall yields with good to excellent enantioselectivities (up to 98%). Various substrates were investigated, and a correlation between the regioselectivity and electronic nature of the substrates was studied. The substrates with electro-donating groups at the alkynyl moiety preferred a 6-endo-dig manner to generated 1H-isochromenes 3 as main products (up to >30:1) while the ones with electron-withdrawing groups were inclined to undergo 5-exo-dig cyclization to form 1,3-dihydroisobenzofurans 4 (up to 1:5). PMID:21967551

Lu, Dengfu; Zhou, Yirong; Li, Yajun; Yan, Shaobai; Gong, Yuefa

2011-10-11

83

Multivariate data analysis as a tool to investigate the reaction kinetics of intramolecular cyclization of enalapril maleate studied by isothermal and non-isothermal FT-IR microscopy  

Microsoft Academic Search

In this paper, the use of multivariate data analysis approach to investigate the kinetics of solid-state reaction monitored via FT-IR thermal microscopy is discussed. The solid-state degradation of enalapril maleate was monitored non-isothermally at temperature range from 25 to 200°C and isothermally at various temperatures (115, 120, 125, 130, and 135°C) for a few hours. The collected FT-IR spectra were

Effendi Widjaja; Geok Hong Lim; Pui Shan Chow; Selvi Tan

2007-01-01

84

Stabilities and dissociation reactions of the Irm(CO)n+ ions observed in TOF-SIMS of Ir4(CO)12 thin layer  

NASA Astrophysics Data System (ADS)

The kinetic energies of Irm(CO)n+ ions observed in the high resolution TOF-SIMS of Ir4(CO)12 layer have been estimated using the post-acceleration electrode method. The observed kinetic energy of secondary ion depends on the number of coordinated CO molecules, but not on the cluster size of Irm+ shell.The signal of Ir5(CO)12+ ion is missing in the observed mass spectrum. The analysis of the uni-molecular dissociation reactions of the complex ions and DFT calculations have shown that this is due to the structural change of Ir5+ shell with the increase of the coordinated CO molecules.

Nakanaga, Taisuke; Nagai, Hidekazu; Saito, Naoaki; Fujiwara, Yukio; Nonaka, Hidehiko

2013-01-01

85

ESR and IR spectroscopic investigation of the reaction of p-nitrosoaniline derivatives with polyamides  

Microsoft Academic Search

There are two active centers in the molecule of p-nitrosoaniline s: the nitroso group, with pronounced nucleophflic properties; and the nitrogen of the amino group, with very low reactivity due to the withdrawal of the free electron pair by the aromatic nucleus. In view of this, the formation of the initial reaction center in the p-nitrosoaniline molecule and the rate

N. V. Antonova; Yu. G. Shevchenko; D. B. Boguslavskii

1973-01-01

86

Charged pion form factor between $Q^2$=0.60 and 2.45 GeV$^2$. I. Measurements of the cross section for the ${^1}$H($e,e'\\\\pi^+$)$n$ reaction  

Microsoft Academic Search

DOI: http:\\/\\/dx.doi.org\\/10.1103\\/PhysRevC.78.045202
Cross sections for the reaction 1H(e,e'pi+)n were measured in Hall C at Thomas Jefferson National Accelerator Facility (JLab) using the high-intensity Continuous Electron Beam Accelerator Facility (CEBAF) to determine the charged pion form factor. Data were taken for central four-momentum transfers ranging from Q2=0.60 to 2.45 GeV2 at an invariant mass of the virtual photon-nucleon system of

Henk Blok; Tanja Horn; Garth Huber; Elizabeth Beise; David Gaskell; David Mack; Vardan Tadevosyan; Jochen Volmer; David Abbott; Konrad Aniol; Heinz Anklin; Christopher Armstrong; John Arrington; Ketevi Assamagan; Steven Avery; O. Baker; Robert Barrett; Christopher Bochna; Werner Boeglin; Edward Brash; Herbert Breuer; C. Chang; Nicholas Chant; Michael Christy; James Dunne; Thomas Eden; Rolf Ent; Howard Fenker; Edward Gibson; Ronald Gilman; Kenneth Gustafsson; Wendy Hinton; Roy Holt; Harold Jackson; Seong uk Jin; Mark Jones; Cynthia Keppel; pyunghun Kim; Wooyoung Kim; Paul King; Andreas Klein; Douglas Koltenuk; Vitali Kovaltchouk; Meihua Liang; Jinghua Liu; George Lolos; Allison Lung; Demetrius Margaziotis; Pete Markowitz; Akihiko Matsumura; David McKee; David Meekins; Joseph Mitchell; Toshinobu Miyoshi; Hamlet Mkrtchyan; Robert Mueller; Gabriel Niculescu; Maria-Ioana Niculescu; Yuichi Okayasu; Lubomir Pentchev; Charles Perdrisat; David Pitz; David Potterveld; Vina Punjabi; Liming Qin; Paul Reimer; Joerg Reinhold; Julie Roche; Philip Roos; Adam Sarty; Ilkyoung Shin; Gregory Smith; Stepan Stepanyan; Liguang Tang; Vladas Tvaskis; Rob van der Meer; Kelley Vansyoc; Derek Van Westrum; Sandra Vidakovic; William Vulcan; Glen Warren; Stephen Wood; C. Xu; Chen Yan; Wenxia Zhao; Xiaochao Zheng; Benedikt Zihlmann

2008-01-01

87

An Efficient One-Pot Green Protocol for the Synthesis of 5-Unsubstituted 3,4-Dihydropyrimidin-2(1H)-Ones Using Recyclable Amberlyst 15 DRY as a Heterogeneous Catalyst via Three-Component Biginelli-Like Reaction  

PubMed Central

An environmentally benign green protocol for the synthesis of 5-unsubstituted 3,4-dihydropyrimidin-2(1H)-ones using Amberlyst 15 DRY as a recyclable catalyst has been developed. The use of resinous, nontoxic, thermally stable, and inexpensive Amberlyst 15 DRY, as a recyclable heterogeneous catalyst, makes the process simple with negligible chemical waste. Among the various solid acid catalysts Amberlyst 15 DRY was found to be the most efficient catalyst with regard to reaction time, yield, and ease of work-up procedure.

Jetti, Srinivasa Rao; Verma, Divya; Jain, Shubha

2012-01-01

88

IR spectroscopy applied subsequent to a proton transfer reaction in the excited state of isolated 3-hydroxyflavone and 2-(2-naphthyl)-3-hydroxychromone.  

PubMed

IR/R2PI-spectroscopy has been applied to the electronic ground and electronically excited states of 3-hydroxyflavone (3-HF) and 2-(2-naphthyl)-3-hydroxychromone (2-NHC) in a supersonic jet yielding direct structural information on the educt and product of a proton transfer reaction. We show that IR spectra of the electronically excited states can be recorded subsequent to a photoinduced chemical reaction, in this case a proton transfer. In combination with DFT and TDDFT calculations structural assignments are performed. PMID:19209360

Bartl, K; Funk, A; Schwing, K; Fricke, H; Kock, G; Martin, H-D; Gerhards, M

2009-01-07

89

IR spectroscopic characterization of intermediates in a gas-phase ionic reaction  

NASA Astrophysics Data System (ADS)

Decarbonylation of acetophenone is a facile process mediated by Co+ complexation. Structures of two species on the gas-phase reaction path have been characterized by their infrared photodissociation spectroscopy, namely the Co+(acetophenone) complex itself, and the decarbonylated but still complexed product ion Co+(C7H8). Infrared spectra over the 500-1800 cm-1 frequency range were obtained by wavelength-dependent multiple-photon dissociation using the FELIX free electron laser and a Fourier-transform ion cyclotron resonance mass spectrometer. Structural characterizations were made by comparison with predicted spectra calculated by density functional theory (DFT) using the B3LYP functional. The initial complex Co+(acetophenone) was found to be intact, with little or no presence of rearrangement or bond-inserted structures. The spectrum indicates a mixture of O-bound and ring-bound isomers of this complex. The decarbonylated product ion was assigned to have the most stable structure, namely Co+(toluene), with no indication of the presence of possible bond-inserted isomers having a two-coordinate metal ion. A decarbonylation path involving metal ion insertion adjacent to the carbonyl group was suggested, and the corresponding bond-inserted complexes were computed to be energetically reasonable intermediate structures on the reaction path.

Dunbar, Robert C.; Moore, David T.; Oomens, Jos

2007-09-01

90

Synthesis, FT-IR, 1H, 13C NMR, ESI MS and PM5 studies of a new Mannich base of polyether antibiotic - Lasalocid acid and its complexes with Li+, Na+ and K+ cations  

NASA Astrophysics Data System (ADS)

The polyether antibiotic Lasalocid acid has been converted to its Mannich base derivative by a chemoselective one-pot reaction with formaldehyde and morpholine through the decarboxylation process. Spectroscopic studies of the structure of this new derivative have shown that in this ortho-phenol Mannich base the Osbnd H⋯N intarmolecular hydrogen bond is present. The compound forms complexes with Li+, Na+ and K+ cations of exclusively 1:1 stoichiometry. The structures of these complexes have been studied and visualized by semi-empirical calculation based on results of spectrometric and spectroscopic investigation. It is demonstrated that in contrast to Lasalocid acid the novel Mannich type derivative forms preferential complexes with Li+ cation.

Huczy?ski, Adam; Rutkowski, Jacek; Brzezinski, Bogumil; Bartl, Franz

2013-03-01

91

The Cl + H2 --> HCl + H reaction induced by IR + UV irradiation of Cl2 in solid para-H2: experiment.  

PubMed

We report IR + UV coirradiation photolysis experiments conducted on Cl(2)-doped para-hydrogen (p-H(2)) crystals at 1.8 K, using pulsed 355 nm UV radiation and cw broad-band near-IR light from a FTIR tungsten source. The amount of HCl photoproduct is monitored using FTIR spectroscopy as a function of the IR + UV exposure time. Detailed analysis of the HCl growth kinetics reveals that the reaction Cl + H(2)(v=1,J=0) --> HCl + H is playing a significant (15%) role in the in situ photochemistry. In contrast, UV-only photolysis experiments conducted under similar conditions produce almost exclusively (99%) isolated Cl atom photofragments, indicating the reaction Cl + H(2)(v=0,J=0) --> HCl + H is not readily occurring. This combination of photolysis experiments confirms that under these conditions, the Cl + H(2) reaction probability increases by a factor greater than 25 for Cl atom reactions with H(2)(v=1) versus H(2)(v=0). These results are therefore consistent with the expectation that vibrational excitation of the H(2) reagent lowers the reaction threshold and increases the reaction cross section for the Cl + H(2) reaction. These experimental studies were motivated by and are compared to the quantum model simulations reported by Korolkov, Manz, and Schild in the accompanying paper. PMID:19378980

Kettwich, Sharon C; Raston, Paul L; Anderson, David T

2009-07-01

92

Spectroscopic (FT-IR, FT-Raman and 1H and 13C NMR) and theoretical in MP2/6-311++G(d,p) and B3LYP/6-311++G(d,p) levels study of benzenesulfonic acid and alkali metal benzenesulfonates  

NASA Astrophysics Data System (ADS)

The FT-IR, FT-Raman and NMR (1H and 13C) spectra of benzenesulfonic acid as well as lithium, sodium, potassium, rubidium and caesium benzenesulfonates were registered, assigned and compared. The molecular structures of ligand and alkali metal salts were discussed. On the basis of quantum mechanical calculations in MP2/6-311++G(d,p) and B3LYP/6-311++G(d,p) levels the geometric parameters, infrared spectra, NMR spectra, the magnetic and geometric aromaticity indices for acid and alkali metal benzenesulfonates and benzoates were obtained. The effect of alkali metal ions on the electronic charge distribution of benzenesulfonic acid was studied and compared with the alkali metal benzoates and benzoic acid.

?widerski, G.; Kalinowska, M.; ?wis?ocka, R.; Wojtulewski, S.; Lewandowski, W.

93

FT-IR Study of the Kinetics and Products of the Reactions of Dimethylsulphide, Dimethylsulphoxide and Dimethylsulphone with Br and BrO  

Microsoft Academic Search

Kinetics and products of the gas-phase reactions of dimethylsulphide (DMS), dimethylsulphoxide (DMSO) and dimethylsulphone (DMSO2) with Br atoms and BrO radicals in air have beeninvestigated using on-line Fourier Transform Infrared Spectroscopy (FT-IR) as analytical technique at 740 ± 5 Torr total pressure and at 296 ± 3 K in a480 L reaction chamber. Using a relative rate method for determining

B. Ballesteros; N. R. Jensen; J. Hjorth

2002-01-01

94

Thermal FT-IR microspectroscopy for rapid detection of solid-state ion-exchange reaction between metoclopramide HCl monohydrate and potassium bromide.  

PubMed

The combination of Fourier transform infrared (FT-IR) microspectroscopy with a thermal analyzer was applied to quickly investigate the solid-state ion-exchange reaction of metoclopramide HCl monohydrate (MCP H(2)O) by clipping MCP H(2)O powder between two KBr or KCl pellets. The physical and ground mixtures of MCP H(2)O or 150 °C-preheated MCP powder and KBr or KCl powders with a weight ratio of 1 : 100 were also prepared and determined by FT-IR microspectroscopy. The samples of MCP H(2)O or 150 °C-preheated MCP were identified by using differential scanning calorimetry (DSC) and thermogravimetric (TG) analysis. The results of present study indicate that the ion-exchange reaction was easily induced between MCP H(2)O and KBr by grinding and heating processes. The possible mechanism of ion-exchange reaction may take place between the HCl salt of MCP H(2)O and a KBr matrix by grinding or heating to yield a mixture of HCl and HBr salts of the MCP sample in the presence of hydrated water. The crystal hydrate played an important role to improve this ion-exchange reaction between MCP H(2)O and KBr. However, no ion-exchange reaction occurred between MCP H(2)O and KCl or between 150 °C-preheated MCP and KBr. The solid-state ion-exchange reaction was more easily determined by this novel thermal FT-IR microspectroscopy than other conventional methods. PMID:21183974

Cheng, Wen-Ting; Wang, Shun-Li; Lin, Shan-Yang

2010-12-23

95

Investigation of photoneutron reactions on {sup 192}Os and {sup 191,193}Ir at energies of relevance for the astrophysical p process  

SciTech Connect

We have investigated the photoneutron reactions on the isotopes {sup 192}Os and {sup 191,193}Ir for astrophysically relevant photon energies just above the neutron separation energy. The experiments were performed using the photoactivation technique at the superconducting Darmstadt linear electron accelerator (S-DALINAC). The measurements extend the existing experimental database on photoneutron reactions in this mass region and serve as an important test for the state-of-the-art statistical model calculations commonly used for the prediction of stellar reaction rates.

Hasper, J.; Zilges, A. [Institut fuer Kernphysik, Universitaet zu Koeln, Zuelpicher Strasse 77, D-50937 Koeln (Germany); Galaviz, D. [Centro de Fisica Nuclear da Universidade de Lisboa, Av. Prof. Gama Pinto 2, PT-1649-003 Lisbon (Portugal); Mueller, S.; Sauerwein, A.; Savran, D.; Schnorrenberger, L.; Sonnabend, K. [Institut fuer Kernphysik, Technische Universitaet Darmstadt, Schlossgartenstrasse 9, D-64289 Darmstadt (Germany)

2009-05-15

96

Measurement of {ital T}{sub 20}(90{degree}) in the {sup 1}H({ital d{searrow}},{gamma}){sup 3}He reaction below deuteron breakup threshold  

SciTech Connect

The tensor analyzing powers of the {sup 1}H({ital d{searrow}},{gamma}){sup 3}He reaction are sensitive to the tensor component of the nucleon-nucleon force, which mixes the {ital L}=2 {ital D} state into the {sup 3}He ground state wave function. Modern Faddeev calculations of this reaction allow a quantitative comparison to the parametrization of the tensor force in the trinucleon system. The {ital T}{sub 20} analyzing power was measured at an incident beam energy of 5.25 MeV and a laboratory angle of 90{degree} ({theta}{sub c.m.}=92.9{degree}), where the comparison to theory is especially rigorous. The measured value of {ital T}{sub 20}(90{sub lab}{sup {degree}}) is {minus}0.035{plus_minus}0.004, which differs by {approx_equal}3{sigma} from a recent Faddeev calculation which uses the separable expansion of the Paris potential. {copyright} {ital 1996 The American Physical Society.}

Browne, K.P.; Pitts, W.K. [University of Louisville, Physics Department, Louisville, Kentucky 40292 (United States); Smith, M.K.; McAninch, J.E.; Knutson, L.D. [University of Wisconsin, Physics Department, Madison, Wisconsin 53706 (United States)

1996-10-01

97

Time-resolved mid-IR spectroscopy of (bio)chemical reactions in solution utilizing a new generation of continuous-flow micro-mixers  

Microsoft Academic Search

A specially designed micro-mixer made of silicon, calcium fluoride, and silicone with an optical transmission path of 8 ?m\\u000a has been used for mid-IR spectroscopy monitoring of mixing-induced chemical reactions in the low millisecond time regime.\\u000a The basic principle of the proposed continuous-flow technique is to mix two liquids introduced in two times two alternatingly\\u000a stacked layers through diffusion at the

Christoph Wagner; Wolfgang Buchegger; Michael Vellekoop; Martin Kraft; Bernhard Lendl

2011-01-01

98

Reactions of H atoms produced by electron irradiation of benzene in solid xenon: IR spectrum of cylohexadienyl radical and possible involvement of HXeC 6H 5  

Microsoft Academic Search

Chemical reactions induced by fast electron irradiation of benzene in solid xenon were studied by EPR and FTIR spectroscopy. Irradiation at 16K leads to H atoms and phenyl radicals. Annealing at 45K results in formation of HXeH and cyclohexadienyl radical (C6H7). A strong IR absorption at 618\\/620cm?1 and several weaker bands were assigned to cyclohexadienyl radical from comparison with EPR

Vladimir I. Feldman; Fedor F. Sukhov; Elizaveta A. Logacheva; Aleksei Yu. Orlov; Irina V. Tyulpina; Daniil A. Tyurin

2007-01-01

99

Synthesis and antimicrobial activities of novel 1H-dibenzo[a,c]carbazoles from dehydroabietic acid.  

PubMed

A series of novel 1H-dibenzo[a,c]carbazole derivatives were synthesized in good yield through reaction of methyl 7-oxo-dehydroabietate with a variety of substituted phenylhydrazines. The structures of the newly synthesized compounds were confirmed by IR, (1)H NMR, MS spectral studies and elemental analysis. All compounds were investigated for their activity against four bacteria (Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas fluorescens) and three fungi (Trichophyton rubrum, Candida albicans and Aspergillus niger). Among the compound tested, 6d, 6e, 6f and 6m exhibited pronounced antibacterial activities and 6e and 6m also showed moderate antifungal activities. Particularly, 6d exhibited stronger antibacterial activity against B. subtilis comparable to positive control. PMID:20702006

Gu, Wen; Wang, Shifa

2010-07-24

100

Synthesis, characterization, and antimicrobial evaluation of carbostyril derivatives of 1H-pyrazole  

PubMed Central

A new series of 12 derivatives of 4-pyrazolyl-N-arylquinoline-2,5-dione (4a–l) were synthesized by one pot base catalyzed cyclocondensation reaction of 1-aryl-5-chloro-3-methyl-1H-pyrazole-4-carbaldehyde (1a–c), Meldrum’s acid (2) and 3-arylamino-5,5-disubstitutedcyclohex-2-enone (3a–d). All the compounds were characterized by elemental analysis, FT-IR, 1H NMR and 13C NMR spectral data and were screened, against six bacterial pathogens, namely Bacillus subtilis, Clostridium tetani, Streptococcus pneumoniae, Salmonella typhi, Vibrio cholerae, Escherichia coli and antifungal activity, against two fungal pathogens Aspergillus fumigatus and Candida albicans, using broth microdilution MIC (minimum inhibitory concentration) method. Some of the compounds were found to be equipotent or more potent than commercial drugs, against most of the employed strains, as evident from the screening data.

Thumar, Nilesh J.; Patel, Manish P.

2011-01-01

101

Teaching 1H NMR Spectrometry Using Computer Modeling.  

ERIC Educational Resources Information Center

Molecular modeling by computer is used to display stereochemistry, molecular orbitals, structure of transition states, and progress of reactions. Describes new ideas for teaching 1H NMR spectroscopy using computer modeling. (Contains 12 references.) (ASK)

Habata, Yoichi; Akabori, Sadatoshi

2001-01-01

102

CP-1-H Analysis Tests.  

National Technical Information Service (NTIS)

A CP-1-H test was done on 10 November 1986. The performance of the experiment is studied using comparisons of the monostatic part and the remote station part, and pulse coded part and the long pulse part. One of the goals of the experiment was to evaluate...

T. Turunen

1987-01-01

103

Evaluation of a setting reaction pathway in the novel composite TiHA-CSD bone cement by FT-Raman and FT-IR spectroscopy  

NASA Astrophysics Data System (ADS)

The aim of this study was to determine a setting reaction pathway in a novel, surgically handy implant material, based on calcium sulfate hemihydrate (CSH) and titanium doped hydroxyapatite (TiHA). The previous studies confirmed superior biological properties of TiHA in comparison to the undoped hydroxyapatite (HA) what makes it highly attractive for future medical applications. In this study the three types of titanium modified HA powders: untreated, calcined at 800 °C, sintered at 1250 °C and CSH were used to produce bone cements. The Fourier Transform-InfraRed (FT-IR) spectroscopy and Raman spectroscopy were applied to evaluate processes taking place during the setting of the studied materials. Our results undoubtedly confirmed that the reaction pathways and the phase compositions differed significantly for set cements and were dependent on the initial heat treatment of TiHA powder. Final materials were multiphase composites consisting of calcium sulfate dihydrate, bassanite, tricalcium phosphate, hydroxyapatite and calcium titanate (perovskite). The FT-IR and Scanning Electron Microscopy (SEM) measurements performed after the incubation of the cement samples in the simulated body fluid (SBF), indicate on high bioactive potential of the obtained bone cements.

Paluszkiewicz, Czes?awa; Czechowska, Joanna; ?lósarczyk, Anna; Paszkiewicz, Zofia

2013-02-01

104

Reactions of ?-dichlorobis(? 3-allyl)palladium(II) with bis(1 -H-benzo-triazolyl-methyl) selenide: Formation of unexpected polymeric structure with dormant Se donor site. Applications of the polymeric Pd-complexes in Heck coupling  

Microsoft Academic Search

Bis(1-H-benzotriazolylmethyl)selenide (L) has been synthesized by reacting Se2? generated in situ with 1-(chloromethyl)-1H-benzotriazole. Proton, C-13 and Se-77 NMR spectra of L are characteristic. ?-Dichlorobis(?3-allyl)palladium(II) reacts with L resulting in polymeric complexes which give single crystals of stoichiometry [Pd(?3-C3H5)(L)]·ClO4\\/PF6·CH3CN (1\\/2). The single crystal X-ray diffraction analyses of these polymeric species reveal that they have chain type of structures, and anions through

Dipanwita Das; Monika Singh; Ajai K. Singh

2009-01-01

105

U1h shaft project  

SciTech Connect

The U1h shaft project is a design/build subcontract to construct one 20 foot (ft) finished diameter shaft to a depth of 1,045 ft at the Nevada Test Site. Atkinson Construction was subcontracted by Bechtel Nevada to construct the U1h Shaft for the Department of Energy. The project consists of furnishing and installing the sinking plant, construction of the 1,045 ft of concrete lined shaft, development of a shaft station at a depth of 976 ft, and construction of a loading pocket at the station. The outfitting of the shaft and installation of a new hoist may be incorporated into the project at a later date. This paper should be of interest to those involved with the construction of relatively deep shafts and underground excavations.

Brian Briggs; R. G. Musick

2000-06-30

106

The electrocatalytic properties of an IrO 2\\/SnO 2 catalyst using SnO 2 as a support and an assisting reagent for the oxygen evolution reaction  

Microsoft Academic Search

Electrocatalysts made of IrO2\\/SnO2 were prepared using the Adams method for solid polymer electrolyte (SPE) water electrolysis. The physicochemical properties of the catalyst were characterized via X-ray diffraction (XRD) and transmission electron microscopy (TEM). The electrochemical properties of the catalyst were investigated using cyclic voltammetry (CV), electrochemical impendence spectroscopy (EIS), chronopotentiometry and Tafel curve measurements in 0.1molL?1 H2SO4 at room

Junyuan Xu; Gaoyang Liu; Jianling Li; Xindong Wang

107

Efficient and general synthesis of oxazino[4,3-a]indoles by cascade addition-cyclization reactions of (1H-indol-2-yl)methanols and vinyl sulfonium salts.  

PubMed

An efficient and general approach to oxazino[4,3-a]indole architectures is described. The addition-cyclization cascade of (1H-indol-2-yl)methanols with vinyl sulfonium salts affords oxazino[4,3-a]indole derivatives in high yields. PMID:21120235

An, Jing; Chang, Ning-Jie; Song, Li-Dong; Jin, Yu-Qin; Ma, Ying; Chen, Jia-Rong; Xiao, Wen-Jing

2010-11-30

108

A study of the reactions of ethanol on CeO{sub 2} and Pd/CeO{sub 2} by steady state reactions, temperature programmed desorption, and in situ FT-IR  

SciTech Connect

The reaction of ethanol on unreduced and H{sub 2}-reduced CeO{sub 2} and 1 wt% Pd/CeO{sub 2} has been investigated by steady state reactions, temperature programmed desorption (TPD), and in situ Fourier transform infrared (FT-IR) spectroscopy. Steady state reactions have shown a zero reaction order dependency for diatomic oxygen at and above 20%, while the addition of Pd to CeO{sub 2} decreases the apparent activation energy of the reaction from 75 kJ/mol on CeO{sub 2} alone to 40 kJ/mol (Pd/CeO{sub 2}). TPD experiments following ethanol adsorption on both CeO{sub 2} and Pd/CeO{sub 2} have shown desorption profiles corresponding to unreacted ethanol and various reaction and decomposition products (acetaldehyde, acetone, CO, CO{sub 2}, and methane). Ethanol conversion to reaction products was increased by the addition of Pd, from 15 to 30% on CeO{sub 2} and H{sub 2}-reduced CeO{sub 2}, to 71 and 63% on Pd/CeO{sub 2} and H{sub 2}-reduced Pd/CeO{sub 2}, respectively.

Yee, A.; Morrison, S.J.; Idriss, H. [Univ. of Auckland (New Zealand)

1999-09-10

109

Time-resolved mid-IR spectroscopy of (bio)chemical reactions in solution utilizing a new generation of continuous-flow micro-mixers.  

PubMed

A specially designed micro-mixer made of silicon, calcium fluoride, and silicone with an optical transmission path of 8 ?m has been used for mid-IR spectroscopy monitoring of mixing-induced chemical reactions in the low millisecond time regime. The basic principle of the proposed continuous-flow technique is to mix two liquids introduced in two times two alternatingly stacked layers through diffusion at the entrance of a 200 ?m wide, 1 cm long micro-fluidic channel also serving as measurement area. By using this special, dedicated arrangement, diffusion lengths and hence the mixing times can be significantly shortened and the overall performance improved in comparison to previous systems and alternative methods. Measurements were carried out in transmission mode using an Fourier transform infrared (FTIR) microscope, recording spectra with spot sizes of 180?×?100 ?m(2) each at defined spots along this channel. Each of these spots corresponds to a specific reaction time: moving the measurement spot towards the entry yields shorter reaction times, moving it towards the channel's end gives longer reaction times. This principle is generic in nature and provides a solution for accurate, chemically induced triggering of reactions requiring the mixing of two liquid reagents or reagent solutions. A typical experiment thus yields up to 85 time-coded data points, covering a time span from 1 to 80 ms at a total reagent consumption of only about 125 ?L. Using the fast neutralization reaction of acetic acid with sodium hydroxide as a model, the time required for 90% mixing was determined to be around 4 ms. Additionally, first experiments on ubiquitin changing its secondary structure from native to "A-state" were carried out, illustrating the potential for time-resolved measurements of proteins in aqueous solutions. PMID:21369756

Wagner, Christoph; Buchegger, Wolfgang; Vellekoop, Michael; Kraft, Martin; Lendl, Bernhard

2011-01-11

110

Near-IR absorbance changes and electrogenic reactions in the microsecond-to-second time domain in Photosystem I.  

PubMed Central

The back-reaction kinetics in Photosystem I (PS I) were studied on the microsecond-to-s time scale in cyanobacterial preparations, which differed in the number of iron-sulfur clusters to assess the contributions of particular components to the reduction of P700+. In membrane fragments and in trimeric P700-FA/FB complexes, the major contribution to the absorbance change at 820 nm (delta A820) was the back-reaction of FA- and/or FB- with lifetimes of approximately 10 and 80 ms (approximately 10% and 40% relative amplitude). The decay of photoinduced electric potential (delta psi) across a membrane with directionally incorporated P700-FA/FB complexes had similar kinetics. HgCl2-treated PS I complexes, which contain FA but no FB, retain both of these kinetic components, indicating that neither can be assigned uniquely to a specific acceptor. These results suggest that FA- reduces P700+ directly and argue for a rapid electron equilibration between FA and FB, which would eliminate their kinetic distinction in a back-reaction. In PsaC-depleted P700-Fx cores, as well as in P700-FA/FB complexes with chemically reduced FA and FB, the major contribution to the delta A820 and the delta psi decay is a biphasic back-reaction of F-X (approximately 400 microseconds and 1.5 ms) with some contribution from A-1 (approximately 10 microseconds and 100 microseconds), the latter of which is variable depending on experimental conditions. The delta A820 decay in a P700-A1 core devoid of all iron-sulfur clusters comprises two phases with lifetimes of 10 microseconds and 130 microseconds (2.7:1 ratio). The biexponential back-reaction kinetics found for each of the electron acceptors may be related to existence of different conformational states of the PS I complex. In all preparations studied, excitation at 532 nm with flash energies exceeding 10 mJ gives rise to formation of antenna 3Chl, which also contributes to delta A820 decay on the tens-of-microsecond time scale. A distinction between delta A820 components related to back-reactions and to 3Chl decay can be made by analysis of flash saturation dependencies and by measurements of kinetics with preoxidized P700.

Vassiliev, I R; Jung, Y S; Mamedov, M D; Semenov AYu; Golbeck, J H

1997-01-01

111

Spectroscopic IR, EPR, and operando DRIFT insights into surface reaction pathways of selective reduction of NO by propene over the Co-BEA zeolite.  

PubMed

Interaction of a Co-BEA catalyst with individual components (NO, C(3)H(6), CO, O(2)) and mixtures simulating the real feed of the selective catalytic reduction (SCR) of nitric oxide in static and pulse experiments at variable temperatures was investigated by means of IR, EPR, and operando DRIFT spectroscopy coupled with QMS/GC analysis of the products. Speciation of cobalt active sites into Co(II), mono- and polynuclear oxo-cobalt species as well as CoO clusters was quantified by IR using CO and NO as probe molecules. The key intermediates, by-products, and final products of the SCR reaction were identified and their spectroscopic signatures ascertained. Based on the spectroscopic operando results, a concise mechanistic scheme of the selective catalytic reduction of nitric oxide by propene, triggered by a two-electron Co(II)/Co(0) redox couple, was developed. It consists of a complex network of the sequential/parallel selective reduction steps that are interlocked by the rival nonselective oxidation of the intermediates and their thermal decomposition. It has been shown that the SCR process is initiated by the chemoselective capture of NO from the reaction mixture by the cobalt active sites leading to the cobalt(II) dinitrosyls, which in the excess of oxygen are partially oxidized to surface nitrates and nitrites. N(2)O is produced by semi-decomposition of the dinitrosyl intermediates on the mononuclear centers, whereas NO(2)via NO oxidation on the polynuclear oxo-cobalt sites. Cyanide and isocyanate species, formed together with propene oxygenates in the course of the C=C bond scission, are the mechanistically pivotal reaction intermediates of C(3)H(6) interaction with the dinitrosyles and NO(3)(-)/NO(2)(-) surface species. Dinitrogen is produced by three main reaction routes involving oxidation of cyanides by NO/NO(2), reduction of dinitrosyls, nitrates, and nitrites by propene oxygenates (medium temperature range) or their reduction by carbon monoxide (high temperature range). PMID:22134498

Pietrzyk, Piotr; Dujardin, Christophe; Góra-Marek, Kinga; Granger, Pascal; Sojka, Zbigniew

2011-12-02

112

On the road from formamide ices to nucleobases: IR-spectroscopic observation of a direct reaction between cyano radicals and formamide in a high-energy impact event.  

PubMed

The formamide-based synthesis of nucleic acids is considered as a nonaqueous scenario for the emergence of biomolecules from inorganic matter. In the current study, we scrutinized the chemical composition of formamide ices mixed with an FeNi meteorite material treated with laser-induced dielectric breakdown plasma created in nitrogen buffer gas. These experiments aimed to capture the first steps of those chemical transformations that may lead to the formation of nucleobases during the impact of an extraterrestrial icy body containing formamide on an early Earth atmosphere. High-resolution FT-IR spectroscopy combined with quantum chemical calculations was used to analyze the volatile fraction of the products formed during such an event. We have found that the spectrum of the evaporated formamide ices is dominated by the spectral signatures of the dimeric form of formamide. Upon exposure to laser sparks, new well-defined bands appear in the spectrum centered at ~820, ~995, and ~1650 cm(-1). On the basis of quantum chemical calculations, these bands can be assigned to the absorptions of 2-amino-2-hydroxy-acetonitrile and to 2-amino-2-hydroxy-malononitrile, which are formed in a direct reaction between formamide and CN(•) radicals upon the high-energy impact event. We also show that there is an exergonic reaction route via these intermediates leading to diaminomaleonitrile, which is generally considered to play a key role in the synthesis of nucleobases. PMID:23193998

Ferus, Martin; Civiš, Svatopluk; Mládek, Arnošt; Šponer, Ji?í; Juha, Libor; Šponer, Judit E

2012-12-12

113

Determination of the rate constants for the NH2(X2B1) + NH2(X2B1) and NH2(X2B1) + H Recombination reactions with collision partners CH4, C2H6, CO2, CF4, and SF6 at low pressures and 296 K. Part 2.  

PubMed

The recombination rate constants for the reactions NH2(X2B1) + NH2(X2B1) + M ? N2H4 + M and NH2(X2B1) + H + M ? NH3 + M, where M was CH4, C2H6, CO2, CF4, or SF6, were measured in the same experiment over presseure ranges of 1-20 and 7-20 Torr, respectively, at 296 ± 2 K. The NH2 radical was produced by the 193 nm laser photolysis of NH3. Both NH2 and NH3 were monitored simultaneously following the photolysis laser pulse. High-resolution time-resolved absorption spectroscopy was used to monitor the temporal dependence of both species: NH2 on the (1)2(21) ? (1)3(31) rotational transition of the (0,7,0)A2A1 ? (0,0,0)X2B1 electronic transition near 675 nm and NH3 in the IR on either of the inversion doublets of the qQ3(3) rotational transition of the ?1 fundamental near 2999 nm. The NH2 self-recombination clearly exhibited falloff behavior for the third-body collision partners used in this work. The pressure dependences of the NH2 self-recombination rate constants were fit using Troe’s parametrization scheme, k(inf), k(0), and F(cent), with k(inf) = 7.9 × 10(-11) cm3 molecule(-1) s(-1), the theoretical value calculated by Klippenstein et al. (J. Phys. Chem. A113, 113, 10241). The individual Troe parameters were CH4, k(0)(CH4) = 9.4 × 10(-29) and F(cent)(CH4) = 0.61; C2H6, k(0)(C2H6) = 1.5 × 10(-28) and F(cent)(C2H6) = 0.80; CO2, k(0)(CO2) = 8.6 × 10(-29) and F(cent)(CO2) = 0.66; CF4, k(0)(CF4) = 1.1 × 10(-28) and F(cent)(CF4) = 0.55; and SF6, k(0)(SF6) = 1.9 × 10(-28) and F(cent)(SF6) = 0.52, where the units of k0 are cm6 molecule(-2) s(-1). The NH2 + H + M reaction rate constant was assumed to be in the three-body pressure regime, and the association rate constants were CH4, (6.0 ± 1.8) × 10(-30); C2H6, (1.1 ± 0.41) × 10(-29); CO2, (6.5 ± 1.8) × 10(-30); CF4, (8.3 ± 1.7) × 10(-30); and SF6, (1.4 ± 0.30) × 10(-29), with units cm6 molecule(-1) s,(-1) and the systematic and experimental errors are given at the 2? confidence level. PMID:22280011

Altinay, Gokhan; Macdonald, R Glen

2012-02-22

114

Novel C?Thionucleosides: Synthesis and Reactions of 1,5? and 1,3?Dialkyl Derivatives of (1,5?Dithio?1?thiomethyl???D,L?arabinopentulo?pyranos?1?yl)?1H?1,2,4?triazole Nucleosides  

Microsoft Academic Search

A series of novel C?thionucleosides: 1,5? and 1,3?dialkyl derivatives of (2,3,4,5?tetra?O?acetyl?1,5?dithio?1?methylthio???D,L?arabinopentulopyranos?1?yl)?1H?1,2,4?triazole nucleosides 10a–d and 17a–c were synthesized, after spontaneous rearrangements, from concerted 1,3?cycloaddition of the sugar nitrile 5 with the reactive 1?(chloroalkyl)?1?aza?2?azoniaallenes 6 and 13 in the presence of a Lewis acid. Deblocking of the acylated nucleosides afforded the free nucleosides 11a–d and 18a–c. The structures of the synthesized compounds

2004-01-01

115

Synthesis of novel 4-(1H-benzimidazol-2-yl)benzene-1,3-diols and their cytotoxic activity against human cancer cell lines.  

PubMed

One-pot synthesis of new biologically active 4-(1H-benzimidazol-2-yl)benzene-l,3-diols has been developed. The compounds were prepared by the reaction of aryl-modified sulfinylbis[(2,4-dihydroxyphenyl)methanethione]s with benzene-l,2-diamines. Their structures were identified using elemental, IR, (1)H-NMR, and mass spectra analyses. The developed method offers short reaction times, relatively large-scale synthesis, easy and quick isolation of the products, and good yields. The cytotoxicity in vitro against the 4 human cancer cell lines: SW707 (rectal), HCV29T (bladder), A549 (lung), and T47D (breast) was determined. The antiproliferative properties of some compounds studies were stronger than those of cisplatin, which was used as a comparator drug. PMID:22076764

Karpi?ka, Monika M; Matysiak, Joanna; Niewiadomy, Andrzej

2011-11-12

116

Diminished CAGE Effect in {p}-H2: IR Identification of Intermediates in Addition Reactions of CL Atom with Unsaturated Hydrocarbons  

NASA Astrophysics Data System (ADS)

We report infrared absorption spectra of several free radicals produced upon reaction of Cl atoms with unsaturated hydrocarbons isolated in solid {p}-H2. Cl atoms were produced by in situ photodissociation of Cl2 isolated in solid {p}-H2 at 365 nm. In experiments with the Cl2/C6H6/{p}-H2 matrices, intense absorption features at 617.0, 719.8, 956.0, and 1430.5 Cm-1 and weaker ones at 577.1, 833.6, 876.8, 833.6, 983.0, 993.5, 1008.0, 1026.4, 1112.5, 1118.5, 1179.0, 1406.5, 1509.4, 2967.2, 3054.3, 3063.4, 3070.9, and 3083.9 Cm-1 appeared upon irradiation of the matrix at 365 nm and increased in intensity upon subsequent annealing of the matrix at 4.8 K for a few minutes. By comparison of vibrational wavenumbers and deuterium isotopic shifts predicted with the B3PW91 and MPW1PW91/aug-cc-pVTZ methods, these features are readily assigned to the ?-complex of ClC6H6 (chlorocyclohexadienyl radical), rather than the previously proposed ?-complex. In experiments with the Cl2/C2H2/{p}-H2 matrices, the 1-chloroethyl radicals (CHClCH3) and chloroethene (C2H3Cl) are identified as the main products of the Cl + C2H2 reaction in solid {p}-H2. The assignments of IR absorption lines at 738.2, 1027.6, 1283.4, 1377.1, 1426.6, 1442.6, and 2861.2 Cm-1 to 1-chloroethyl radicals are based on comparison of the observed vibrational wavenumbers and 13C- and D-isotopic shifts with those predicted with the B3LYP and MP2/aug-cc-pVDZ methods. These results indicate that the primary products of the addition reaction Cl + C2H2, the 2-chlorovinyl radicals, are unstable; they react readily with {p}-H2 to form CHClCH3 and C2H3Cl. If time permits, other examples such as Cl + 1, 3-butadien and H + C6H6 or C6H5Cl will be discussed. These results serve as excellent examples to demonstrate that the diminished cage effect of solid {p}-H2 makes production of free radicals via bimolecular reactions feasible.

Lee, Yuan-Pern; Bahou, Mohammed; Golec, Barbara

2011-06-01

117

Synthesis of chromeno[2,3-d]imidazol-9(1H)-ones via tandem reactions of 3-iodochromones with amidines involving copper-catalyzed C-H functionalization and C-O bond formation.  

PubMed

A novel six-membered heterocyclic skeleton of imidazochromone was prepared via an efficient one-pot reaction including a key step of copper-catalyzed aerobic C-H intramolecular cycloetherification. Notably, this process does not require the presence of strong para electron-withdrawing groups on the phenol component. Also, the results of this effort show that acyl phenols containing electron-rich heterocycles participate in an efficient C-H activation/C-O formation process. PMID:23944967

Sheng, Jia; Chao, Bo; Chen, Hong; Hu, Youhong

2013-08-14

118

Measurement of the Two-Halo Neutron Transfer Reaction {sup 1}H({sup 11}Li,{sup 9}Li){sup 3}H at 3A MeV  

SciTech Connect

The p({sup 11}Li,{sup 9}Li)t reaction has been studied for the first time at an incident energy of 3A MeV at the new ISAC-2 facility at TRIUMF. An active target detector MAYA, built at GANIL, was used for the measurement. The differential cross sections have been determined for transitions to the {sup 9}Li ground and first excited states in a wide range of scattering angles. Multistep transfer calculations using different {sup 11}Li model wave functions show that wave functions with strong correlations between the halo neutrons are the most successful in reproducing the observation.

Tanihata, I.; Alcorta, M.; Bandyopadhyay, D.; Bieri, R.; Buchmann, L.; Davids, B.; Galinski, N.; Howell, D.; Mills, W.; Mythili, S.; Openshaw, R.; Padilla-Rodal, E.; Ruprecht, G.; Sheffer, G.; Shotter, A. C.; Trinczek, M.; Walden, P.; Savajols, H.; Roger, T.; Caamano, M. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3 (Canada); GANIL, Bd Henri Becquerel, BP 55027, 14076 Caen Cedex 05 (France); Saint Mary's University, 923 Robie St., Halifax, Nova Scotia B3H 3C3 (Canada); ANL, 9700 S. Cass Ave., Argonne, Illinois 60439 (United States); LLNL, L-414, P.O. Box 808, Livermore, California 94551 (United States)] (and others)

2008-05-16

119

Highly effective Ir(x)Sn(1-x)O2 electrocatalysts for oxygen evolution reaction in the solid polymer electrolyte water electrolyser.  

PubMed

We developed an advanced surfactant-assistant method for the Ir(x)Sn(1-x)O(2) (0 < x ? 1) nanoparticle (NP) preparation, and examined the OER performances by a series of half-cell and full-cell tests. In contrast to the commercial Ir black, the collective data confirmed the outstanding activity and stability of the fabricated Ir(x)Sn(1-x)O(2) (x = 1, 0.67 and 0.52) NPs, which could be ascribed to the amorphous structure, good dispersion, high pore volume, solid-solution state and Ir-rich surface for bi-metal oxides, and relatively large size (10-11 nm), while Ir(0.31)Sn(0.69) exhibited poor electro-catalytic activity because of the separated two phases, a SnO(2)-rich phase and an IrO(2)-rich phase. Furthermore, compared with highly active IrO(2), the improved durability, precious-metal Ir utilization efficiency and correspondingly reduced Ir loading were realized by the addition of Sn component. When the Ir(0.52)Sn(0.48)O(2) cell operated at 80 °C using Nafion® 115 membrane and less than 0.8 mg cm(-2) of the noble-metal Ir loading, the cell voltages we achieved were 1.631 V at 1000 mA cm(-2), and 1.821 V at 2000 mA cm(-2). The IR-free voltage at the studied current density was very close to the onset voltage of oxygen evolution. The only 50 ?V h(-1) of voltage increased for the 500 h durability test at 500 mA cm(-2). In fact, these results are exceptional compared to the performances for OER in SPEWE cells known so far. This work highlights the potential of using highly active and stable IrO(2)-SnO(2) amorphous NPs to enhance the electrolysis efficiency, reduce the noble-metal Ir loading and thus the cost of hydrogen production from the solid polymer electrolyte water electrolysis. PMID:23338525

Li, Guangfu; Yu, Hongmei; Wang, Xunying; Sun, Shucheng; Li, Yongkun; Shao, Zhigang; Yi, Baolian

2013-01-22

120

OH reaction rate constant, IR absorption spectrum, ozone depletion potentials and global warming potentials of 2-bromo-3,3,3-trifluoropropene  

NASA Astrophysics Data System (ADS)

The rate constant for the gas phase reaction of OH radicals with BTP (2-bromo-3,3,3-trifluoropropene, CH2 = CBrCF3) was measured using a flash photolysis resonance-fluorescence technique over the temperature range 220 K to 370 K. The Arrhenius plot was found to exhibit noticeable curvature. The temperature dependence of the rate constant can be represented askBTP(220 - 370 K) = 4.85 × 10-13 × (T/298)0.92 × exp{+613/T} cm3 molecule-1 s-1. For atmospheric modeling purposes, kBTP(T) can be equally well represented by the standard Arrhenius expression kBTP(220 - 298 K) = 1.05 × 10-12 × exp{+381/T} cm3 molecule-1 s-1. The IR absorption cross-sections of BTP were also measured between 450 cm-1 and 1900 cm-1. BTP atmospheric lifetime, Ozone Depletion Potential (ODP), and Global Warming Potential (GWP) were evaluated in the Whole Atmosphere Community Climate Model for land emissions from 30 to 60°N and from 60°S to 60°N. The global, annual average atmospheric lifetime of BTP in the former scenario was 7.0 days, its ODP was 0.0028, and its GWP (100-yr time horizon) was 0.0050; in the latter scenario, the global, annual average BTP lifetime was 4.3 days, ODP was 0.0052, and 100-yr GWP was 0.0028. The short lifetime, low ODP, and low GWP indicate that BTP should have minimal effects on ozone and climate. Little BTP reaches the stratosphere in either emission scenario, but 27% of the ozone loss in the 30 to 60°N scenario and 46% of the ozone loss in the 60°S to 60°N scenario occurs above the tropopause due to Bry from BTP.

Patten, Kenneth O.; Khamaganov, Victor G.; Orkin, Vladimir L.; Baughcum, Steven L.; Wuebbles, Donald J.

2011-12-01

121

Termination of the W2Oy-+H2O/D2O-->W2Oy+1-+H2/D2 sequential oxidation reaction: An exploration of kinetic versus thermodynamic effects  

NASA Astrophysics Data System (ADS)

Several mechanisms proposed and calculated for the sequential oxidation of tungsten suboxide clusters by H2O/D2O [Mayhall et al., J. Chem. Phys. 131, 144302 (2009)] are evaluated using anion photoelectron spectroscopy of an apparent intermediate, W2O6D2-. The spectrum of W2O6D2- is consistent with the W2O5-+D2O-->W2O6-+D2 intermediate in which the initial water addition involves the interaction of the oxygen from D2O with a tungsten atom, approaching from a direction with the least repulsion from the W2O5- oxygen atoms, coupled with the interaction between a deuterium with a tungsten-tungsten bridging oxygen on the cluster. The presence of W2O6H2- and W2O6D2- suggests that there is insufficient internal energy in the complex to surmount the barrier for rearrangement required for tungsten hydride and hydroxide formation necessary for H2 or D2 evolution, which was calculated to be energetically favorable. The quality of the calculations is verified by direct comparison between experimental photoelectron spectra of W2O5- and W2O6- and spectral simulations generated from the lowest energy structures calculated for W2O5-, W2O6- and their corresponding neutrals. The results shed light on the importance of repulsion on the pathway a reaction follows under room temperature conditions.

Rothgeb, David W.; Hossain, Ekram; Mayhall, Nicholas J.; Raghavachari, Krishnan; Jarrold, Caroline Chick

2009-10-01

122

Improved homopolymer separation to enable the application of 1H NMR and HPLC for the determination of the reaction parameters of the graft copolymerization of acrylic acid onto starch.  

PubMed

Graft copolymers of starch with acrylic acid are a promising green, bio based material with many potential applications. The grafting of acrylic acid onto cassava starch in an aqueous medium initiated by Fenton's reagent has been studied. Common grafting result parameters are add-on (yield) and graft efficiency (selectivity). However, the analysis of the reaction products and an accurate determination of these parameters stand or fall with a complete separation of the entangled but ungrafted homopolymer from the grafted product. Therefore, this separation is the core of the newly developed analytical procedure. An appropriate solvent has been selected with dedicated testing from the range methanol, ethanol, acetone, dioxane, 2-propanol, and 1-propanol. Acetone showed the best performance in many respects. It has a high dissolving power for the homopolymer, as well as the highest yield of precipitation for the starch derivatives and it is the most economical in use. After the successful separation, the precipitated graft copolymers could be analyzed quantitatively by nuclear magnetic resonance. The liquid with homopolymer and unreacted monomer was analyzed by high pressure liquid chromatography. Proof of grafting has been found by FTIR and TGA analyses. The mass balance calculation shows a systematic error which appears fairly consistent: 18.0±2.5 wt%. This was used as a correction factor in the calculation of the grafting parameters but more importantly, it means that the method we developed has a high level of repeatability, in the order of 97%. PMID:23435285

Witono, Judy R; Marsman, Jan Henk; Noordergraaf, Inge-Willem; Heeres, Hero J; Janssen, Leon P B M

2013-01-31

123

Campath-1H Treatment of Multiple Sclerosis  

Microsoft Academic Search

Campath-1H is a humanised monoclonal antibody that targets CD52, a cell surface protein expressed on lymphocytes, monocytes and eosinophils. A single dose of Campath-1H leads to a rapid and profound lymphopenia. Campath-1H has been used in Cambridge as an experimental treatment of multiple sclerosis for more than 15 years. Here, we summarise our clinical and laboratory findings, describing how this

Joanne L. Jones; Alasdair J. Coles

2008-01-01

124

Electronic and steric effects on the mechanism of the inverse electron demand Diels-Alder reaction of 2-aminopyrroles with 1,3,5-triazines: identification of five intermediates by 1H, 13C, 15N, and 19F NMR spectroscopy.  

PubMed

The inverse electron demand Diels-Alder (IEDDA) reaction of 1-tert-butyl-2-aminopyrrole with 2,4,6-tris(trifluoromethyl)-1,3,5-triazine in THF-d(8) to give a pyrrolo[2,3-d]pyrimidine was studied by (1)H, (13)C, (15)N, and (19)F NMR spectroscopy, and five intermediates were identified. A zwitterion was the first intermediate detected, and it cyclized to a tricyclic adduct and its conjugate acid. It also gave a neutral imine via a proton switch. The tricyclic adduct underwent a retro-Diels-Alder reaction, but the expected CF(3)CN was not detected. NMR indicated that the amino group of the 2-aminopyrrole was bonded to the CF(3)CN to form a trifluoroacetoamidinium ion. The products of the retro-Diels-Alder reaction reacted rapidly with each other to give the final intermediate observed. Acid-catalyzed loss of an amidine gave the final aromatic product. This is the first study in which direct experimental evidence for the order of the steps in the IEDDA cascade reaction of 1,3,5-triazines with amino-containing dienophiles has been obtained. This study and analogous 1,3-dipolar cycloaddition reactions, in which zwitterions have been detected or proposed, have two factors in common: electronic effects that stabilize the zwitterions and steric effects that inhibit their cyclization. PMID:19053577

De Rosa, Michael; Arnold, David

2009-01-01

125

Charged pion form factor between Q{sup 2}=0.60 and 2.45 GeV{sup 2}. I. Measurements of the cross section for the {sup 1}H(e,e{sup '}{pi}{sup +})n reaction  

SciTech Connect

Cross sections for the reaction {sup 1}H(e,e{sup '}{pi}{sup +})n were measured in Hall C at Thomas Jefferson National Accelerator Facility (JLab) using the high-intensity Continuous Electron Beam Accelerator Facility (CEBAF) to determine the charged pion form factor. Data were taken for central four-momentum transfers ranging from Q{sup 2}=0.60 to 2.45 GeV{sup 2} at an invariant mass of the virtual photon-nucleon system of W=1.95 and 2.22 GeV. The measured cross sections were separated into the four structure functions {sigma}{sub L},{sigma}{sub T},{sigma}{sub LT}, and {sigma}{sub TT}. The various parts of the experimental setup and the analysis steps are described in detail, including the calibrations and systematic studies, which were needed to obtain high-precision results. The different types of systematic uncertainties are also discussed. The results for the separated cross sections as a function of the Mandelstam variable t at the different values of Q{sup 2} are presented. Some global features of the data are discussed, and the data are compared with the results of some model calculations for the reaction {sup 1}H(e,e{sup '}{pi}{sup +})n.

Blok, H. P. [Dept. of Physics, VU university, NL-1081 HV Amsterdam (Netherlands); NIKHEF, Postbus 41882, NL-1009 DB Amsterdam (Netherlands); Horn, T. [University of Maryland, College Park, Maryland 20742 (United States); Physics Division, TJNAF, Newport News, Virginia 23606 (United States); Huber, G. M.; Brash, E. J.; Kovaltchouk, V.; Lolos, G. J.; Meer, R. L. J. van der; Vidakovic, S.; Xu, C. [University of Regina, Regina, Saskatchewan S4S 0A2 (Canada); Beise, E. J.; Breuer, H.; Chang, C. C.; Chant, N.; Gustafsson, K.; King, P. M.; Liu, J.; Roos, P. G. [University of Maryland, College Park, Maryland 20742 (United States); Gaskell, D.; Mack, D. J.; Abbott, D. [Physics Division, TJNAF, Newport News, Virginia 23606 (United States)] (and others)

2008-10-15

126

Measurement of Imino 1H-1H Residual Dipolar Couplings in RNA  

PubMed Central

Imino 1H-15N residual dipolar couplings (RDCs) provide additional structural information that complements standard 1H-1H NOEs leading to improvements in both the local and global structure of RNAs. Here, we report measurement of imino 1H-1H RDCs for the Iron Responsive Element (IRE) RNA and native E. coli tRNAVal using a BEST-Jcomp-HMQC2 experiment. 1H-1H RDCs are observed between the imino protons in G-U wobble base pairs and between imino protons on neighboring base pairs in both RNAs. These imino 1H-1H RDCs complement standard 1H-15N RDCs because the 1H-1H vectors generally point along the helical axis, roughly perpendicular to 1H-15N RDCs. The use of longitudinal relaxation enhancement increased the signal-to-noise of the spectra by ~3.5-fold over the standard experiment. The ability to measure imino 1H-1H RDCs offers a new restraint, which can be used in NMR domain orientation and structural studies of RNAs.

Latham, Michael P.; Pardi, Arthur

2010-01-01

127

Determination of the Langmuir adsorption isotherms of under- and over-potentially deposited hydrogen for the cathodic H 2 evolution reaction at poly-Ir\\/aqueous electrolyte interfaces using the phase-shift method  

Microsoft Academic Search

The Langmuir adsorption isotherms of under-potentially deposited hydrogen (UPD H) and over-potentially deposited hydrogen (OPD H) for the cathodic H2 evolution reaction (HER) at poly-Ir\\/0.5M H2SO4 and 0.05M KOH aqueous electrolyte interfaces have been studied using cyclic voltammetric, differential pulse voltammetric, and ac impedance techniques. The behavior of the lagged phase shift (0°????90°) for the optimum intermediate frequency can be

Jang H. Chun; Sang K. Jeon; Bok K. Kim; Jin Y. Chun

2005-01-01

128

A complete 1H and 13C NMR data assignment for 3-phenylmethylene-1H,3H-naphtho-[1,8-c,d]-pyran-1-one.  

PubMed

Complete assignments of the 1H and 13C NMR chemical shifts for 3-phenylmethylene-1H,3H-naphtho-[1,8-c,d]-pyran-1-one were done by means of one- and two-dimensional NMR techniques, including 1H-(1)H COSY, HMQC and HMBC spectra. Ab initio quantum chemistry calculations and a shift prediction by an incremental method provided values close to the proposed assignments. All mid-IR spectral bands are given as reference data. The DRIFT FTIR, ATR FTIR and Raman spectra are given as a Supplementary data in JCAMP-DX format, version 4.24. In addition, a method of compound's synthesis, that has the product yield higher as compared to already known data in the literature, is given. PMID:21169052

Penchev, Plamen N; Stoyanov, Neyko M; Marinov, Marin N

2010-12-02

129

The synthesis, X-ray crystal structure and optical properties of novel 1-ferrocenyl-2-(3-phenyl-1 H-1,2,4-triazol-5-ylthio)ethanone derivatives  

NASA Astrophysics Data System (ADS)

A series of novel 1-ferrocenyl-2-(3-phenyl-1 H-1,2,4-triazol-5-ylthio)ethanone derivatives was synthesized by the reaction of 3-substituted-1 H-1,2,4-triazole-5-thiol and chloroacetyl ferrocene in the presence of sodium hydride and potassium iodide at reflux. The structures of the new compounds were determined by IR and 1H NMR spectroscopy and HRMS. The structure of compound 5c was established by X-ray crystallography. UV-vis absorption and fluorescence spectra were recorded in ethanol and dichloromethane. The results showed that compounds 5a-g display similar absorptions ranging from 300 to 500 nm and maximal emission bands are about 566 nm. The intensity of fluorescence and maximal emission bands are dependent on the groups bonded to triazole rings.

Liu, Wei-Yong; Xie, Yong-Sheng; Zhao, Bao-Xiang; Lian, Song; Lv, Hong-Shui; Gong, Zhong-Liang; Shin, Dong-Soo

2010-09-01

130

Measurements of the neutron electric to magnetic form factor ratio G{sub En}/G{sub Mn} via the {sup 2}H(e{yields},e{sup '}n{yields}){sup 1}H reaction to Q{sup 2}=1.45 (GeV/c){sup 2}  

SciTech Connect

We report values for the neutron electric to magnetic form factor ratio, G{sub En}/G{sub Mn}, deduced from measurements of the neutron's recoil polarization in the quasielastic {sup 2}H(e{yields},e{sup '}n{yields}){sup 1}H reaction, at three Q{sup 2} values of 0.45, 1.13, and 1.45 (GeV/c){sup 2}. The data at Q{sup 2}=1.13 and 1.45 (GeV/c){sup 2} are the first direct experimental measurements of G{sub En} employing polarization degrees of freedom in the Q{sup 2}>1 (GeV/c){sup 2} region and stand as the most precise determinations of G{sub En} for all values of Q{sup 2}.

Plaster, B. [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); California Institute of Technology, Pasadena, California 91125 (United States); Semenov, A.Yu.; Semenova, I.A. [Kent State University, Kent, Ohio 44242 (United States); Joint Institute for Nuclear Research, Dubna RU-141980 (Russian Federation); Aghalaryan, A.; Asaturyan, R.; Mkrtchyan, H.; Stepanyan, S.; Tadevosyan, V. [Yerevan Physics Institute, Yerevan 375036 (Armenia); Crouse, E.; Finn, J.M.; Perdrisat, C.; Roche, J. [College of William and Mary, Williamsburg, Virginia 23187 (United States); MacLachlan, G.; Opper, A.K. [Ohio University, Athens, Ohio 45701 (United States); Tajima, S.; Churchwell, S.; Howell, C.R. [Duke University and TUNL, Durham, North Carolina 27708 (United States); Tireman, W. [Kent State University, Kent, Ohio 44242 (United States); Northern Michigan University, Marquette, Michigan 49855 (United States); Ahmidouch, A. [North Carolina A and T State University, Greensboro, North Carolina 27411 (United States); Anderson, B. D. [Kent State University, Kent, Ohio 44242 (United States)] (and others)

2006-02-15

131

XRD, Raman and FT-IR spectroscopic observations of nanosized TiO 2 synthesized by the sol–gel method based on an esterification reaction  

Microsoft Academic Search

Ti(IV)-isopropoxide was hydrolyzed with water molecules generated “in situ” by an esterification between carboxylic acid and alcohol providing excellent control of the hydrolysis and condensation rate. Raman and FT-IR spectra of the TiO2–acetate precursor suggested that the organic ligand is chemically bound to the titanium. With heating of the TiO2–acetate precursor up to 320°C, the surface area increased from 3

M. Ivanda; S Popovi?; M Goti?

1999-01-01

132

FT–IR study of the ring-retaining products from the reaction of OH radicals with phenol, o-, m-, and p-cresol  

Microsoft Academic Search

The ring-retaining products of the OH-initiated degradation of phenol and o-, m-, and p-cresol in the presence of NOx have been investigated and their formation yields determined. The experiments were carried out in a large volume reactor at (298±2)K and 1000mbar total pressure of synthetic air using FT–IR spectroscopy for the analysis of reactants and products.The products observed and their

Romeo Iulian Olariu; Björn Klotz; Ian Barnes; Karl Heinz Becker; Raluca Mocanu

2002-01-01

133

Aqueous organometallic chemistry. 2. {sup 1}H NMR spectroscopic, synthetic, and structural study of the chemo- and diastereoselective reactions of [Cp{sup *}Rh(H{sub 2}O){sub 3}]{sup 2+} with nitrogen ligands as a function of pH  

SciTech Connect

The reactions of a new Cp{sup *}Rh aqua synthon, [Cp{sup *}Rh(H{sub 2}O){sub 3}]{sup 2+} (1), at acidic pH values (2-6) with aniline (2), pyridine (3), and L-phenylalanine (4) have provided interesting chemo- and diastereoselectivities as studied by {sup 1}H NMR, FAB/MS, and single-crystal X-ray crystallography. The reaction of 2 and aqua complex 1, at pH values from 4 to 6, quantitatively provided [Cp{sup *}Rh({eta}{sup 6}-aniline)]{sup 2+} (5); the structure of 5 was unequivocally determined by a single-crystal X-ray analysis, which also showed an approximate 25% {eta}{sup 5} component. Compound 3 reacted with 1, at pH 2-6, to selectively provide [Cp{sup *}Rh({eta}{sup 1}-pyridine){sub n} (H{sub 2}O){sub 3-n}]{sup 2+} (n = 1-3) complexes 6a-c as a function of pH. Surprisingly, complex 1 reacted with 4, from pH 4 to 6, to provide only one diastereomer of the known cyclic trimer [(Cp{sup *}Rh)({mu}-{eta}{sup 1}-(OCO):{eta}{sup 2}-(N,OCO)-L-phe nylalanine)]{sub 3}{sup 3+} (7; S{sub C},S{sub C},S{sub C},S{sub Rh},S{sub Rh},S{sub Rh},) an example of a one-step, highly diastereoselective reaction in H{sub 2}O. 8 refs., 4 figs., 2 tabs.

Ogo, Seiji; Chen, H.; Fish, R.H. [Lawrence Berkeley Lab., CA (United States); Olmstead, M.M. [Univ. of California, Davis, CA (United States)

1996-04-16

134

Test of Low-Energy Theorems for 1H(?-->, ?0)1H in the Threshold Region  

NASA Astrophysics Data System (ADS)

The photon asymmetry in the reaction 1H(?-->,?0)1H close to threshold has been measured for the first time with the photon spectrometer TAPS using linearly polarized photons from the tagged-photon facility at the Mainz Microtron MAMI. The total and differential cross sections were also measured simultaneously with the photon asymmetry. This allowed determination of the S-wave and all three P-wave amplitudes. The values obtained at threshold are E0+ = [-1.33+/-0.08(stat)+/-0.03(syst)]×10- 3/m?+, P1 = [9.47+/-0.08(stat)+/-0.29(syst)]×10- 3q/m2?+, P2 = [-9.46+/-0.1(stat)+/-0.29(syst)]×10- 3q/m2?+, and P3 = [11.48+/-0.06(stat)+/-0.35(syst)]×10- 3q/m2?+.

Schmidt, A.; Achenbach, P.; Ahrens, J.; Arends, H. J.; Beck, R.; Bernstein, A. M.; Hejny, V.; Kotulla, M.; Krusche, B.; Kuhr, V.; Leukel, R.; MacGregor, I. J.; McGeorge, J. C.; Metag, V.; Olmos de León, V. M.; Rambo, F.; Siodlaczek, U.; Ströher, H.; Walcher, Th.; Weiß, J.; Wissmann, F.; Wolf, M.

2001-12-01

135

The Discovery-Oriented Approach to Organic Chemistry. 4. Epoxidation of p-Methoxy-trans-b-methylstyrene: An Exercise in NMR and IR Spectroscopy for Sophomore Organic Laboratories  

NASA Astrophysics Data System (ADS)

Epoxidation of alkenes using peroxyacids is one of the most fundamental reactions in organic chemistry, yet there are very few examples of laboratory experiments that illustrate this important reaction. We have developed a discovery-oriented lab experiment that illustrates epoxidation of alkenes as well as the reactivity of epoxides toward acids. The experiment involves reaction of p-methoxy-trans-b-methylstyrene (trans-anethole) with m-chloroperoxybenzoic acid (MCPBA), in both the absence and presence of a buffer, followed by product identification using 1H NMR, 13C NMR, and IR spectroscopy. The added element of discovery ensures that students' interest and enthusiasm are retained.

Centko, Rebecca S.; Mohan, Ram S.

2001-01-01

136

One-pot synthesis of ferrocenyl ketones containing biaryls and 6-aryl-2-ferrocenylquinolines via Ir/Pd-cocatalyzed ?-alkylation/Suzuki reaction.  

PubMed

An efficient PPh3-cyclometalated iridium(III) benzo[h]quinoline hydride 1/Pd(OAc)2-cocatalyzed three-component ?-alkylation/Suzuki reaction has been developed. The three-component reaction of 4-bromobenzyl alcohol, acetylferrocene, and arylboronic acids gives ferrocenyl ketones containing biaryls in moderate to good yields. This method was successfully applied to a one-pot synthesis of 6-aryl-2-ferrocenyl quinolines, using (2-amino-5-bromophenyl)methanol instead of 4-bromobenzyl alcohol. PMID:23924342

Xu, Chen; Hao, Xin-Qi; Xiao, Zhi-Qiang; Wang, Zhi-Qiang; Yuan, Xiao-Er; Fu, Wei-Jun; Ji, Bao-Ming; Song, Mao-Ping

2013-08-16

137

X-ray molecular structures and multinuclear NMR studies of the tetranuclear iridium clusters [Ir 4(CO) 7(? 4-? 3-PhCC(H)CCPh)(?-PPh 2) 3] and [Ir 4(CO) 7(? 3-? 2-HCCPh)(? 1-CCPh)(?-PPh 2) 3  

Microsoft Academic Search

The reaction of [HIr4(CO)10(?-PPh2)] with two equiv. of Ph2PCCPh produced [HIr4(CO)8(Ph2PCCPh)2(?-PPh2)] (1) in quantitative yield. Mild thermolysis of 1 gave [Ir4(CO)7(?4-?3-PhCC(H)CCPh)(?-PPh2)3] (2) and [Ir4(CO)7(?3-?2-HCCPh)(?1-CCPh)(?-PPh2)3] (3) in good yields. These compounds were characterized with analytical and spectroscopic data including 1H, 13C and 31P NMR (1 and 2D) spectroscopy, and their molecular structures were established by X-ray diffraction studies. The metal frameworks

Maria Helena Araujo; Regina M. S. Pereira; Maria D. Vargas; Dario Braga; Fabrizia Grepioni

2005-01-01

138

Phototoxicity of (1H-indenyl)thiophenes.  

PubMed

The (1H-indenyl)thiophene derivatives 2 and 3 were recently reported to be excellent singlet oxygen sensitizers, comparable to alpha-terthienyl (1). The phototoxicity of these compounds was compared, using human erythrocytes, Aedes aegypti mosquito larvae, Daphnia magna, and fish (fathead minnows, Pimephales promelas). The known ranking of the photooxidation properties was found to be a good predictor of phototoxic properties in erythrocytes and mosquito larvae but not in daphnias. All three compounds photosensitized the cleavage of supercoiled pBR322 DNA to the same extent. PMID:8378432

Herrnreiter, M; Kagan, J; Chen, X; Lau, K Y; D'Auria, M; Vantaggi, A

1993-07-01

139

De novo design of chiral organotin cancer drug candidates: validation of enantiopreferential binding to molecular target DNA and 5'-GMP by UV-visible, fluorescence, (1)H and (31)P NMR.  

PubMed

N,N-bis[(R-/S-)-1-benzyl-2-ethoxyethane] tin (IV) complexes were synthesized by applying de novo design strategy by the condensation reaction of (R-/S-)2-amino-2-phenylethanol and dibromoethane in presence of dimethyltin dichloride and thoroughly characterized by elemental analysis, conductivity measurements, IR, ESI-MS, (1)H, (13)C and (119)Sn, multinuclear NMR spectroscopy and XRD study. Enantioselective and specific binding profile of R-enantiomer 1 in comparison to S-enantiomer 2 with ultimate molecular target CT-DNA was validated by UV-visible, fluorescence, circular dichroism, (1)H and (31)P NMR techniques. This was further corroborated well by interaction of 1 and 2 with 5'-GMP. PMID:21945056

Arjmand, Farukh; Sharma, Girish Chandra; Sayeed, Fatima; Muddassir, Mohd; Tabassum, Sartaj

2011-08-26

140

Kinetics of the F + NO 2 + M ? FNO 2 + M reaction studied by pulse radiolysis combined with time-resolved IR and UV spectroscopy  

Microsoft Academic Search

The title reaction was initiated by the pulse radiolys ofSF6NO2 gas mixtures, and the formation of FNO2 was studied by time-resolved infrared spectroscopy employing strong rotational transitions within the?1and?4 bands of FNO2. The pressure dependence of the formation kinetics was studied with SF6 pressures of 5–1000 mbar at 298 K. Comparative studies were carried out by monitoring the decay kinetics

Palle Pagsberg; Alfred Sillesen; Jerzy T. Jodkowski; Emil Ratajczak

1996-01-01

141

ALBERMARLE PAMLICO IR 2002  

EPA Science Inventory

The 2002 Albermarle Pamlico Implementation Review (IR) highlights recent successes and challenges with the estuary program. Various components within the IR include: CCMP implementation, outlining priority management actions, public involvement, stakeholder contribution, and limi...

142

Nd(III) and Dy(III) coordination compounds based on 1H-tetrazolate-5-acetic acid ligands: Synthesis, crystal structures and catalytic properties  

NASA Astrophysics Data System (ADS)

Reactions of 1H-tetrazolate-5-acetic acid(H2tza) with Nd(NO3)3·6H2O or Dy(NO3)3·6H2O with the presence of KOH under solvothermal conditions, produced two new coordination compounds, [M2(tza)3(H2O)6]·2H2O [M=Nd(1), Dy(2)]. Both compounds were structurally characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. Compounds 1 and 2 reveal 1D structures via bridging tza as linker. Furthermore, the compounds 1 and 2 showed a specific and good catalytic behavior for the polymerization of styrene, and the polymerization showed controlled characteristics.

Li, Qiao-Yun; Chen, Dian-Yu; He, Ming-Hua; Yang, Gao-Wen; Shen, Lei; Zhai, Chun; Shen, Wei; Gu, Kun; Zhao, Jing-Jing

2012-06-01

143

Atmospheric chemistry of sulfuryl fluoride: reaction with OH radicals, Cl atoms and O3, atmospheric lifetime, IR spectrum, and global warming potential.  

PubMed

Sulfuryl fluoride (SO2F2) is a radiatively active industrial chemical released into the atmosphere in significant (ktonne/ year) quantities. The potential for SO2F2 to contribute to radiative forcing of climate change needs to be assessed. Long path length FTIR/smog chamber techniques were used to investigate the kinetics of the gas-phase reactions of Cl atoms, OH radicals, and O3 with SO2F2, in 700 Torr total pressure of air or N2 at 296 +/- 1 K. Upper limits of k(Cl + SO2F2) < 9 x 10(-19), k(OH + SO2F2) < 1.7 x 10(-14) and k(O3 + SO2F2) < 5.5 x 10(-24) cm3 molecule(-1) s(-1) were determined. Reaction with Cl atoms, OH radicals, or O3 does not provide an efficient removal mechanism for SO2F2. The infrared spectrum of SO2F2 is reported and a radiative efficiency of 0.196 W m(-2) ppbv(-1) was calculated. Historic production data estimates are presented which provide an upper limit for expected atmospheric concentrations. The radiative forcing of climate change associated with emissions of SO2F2 depends critically on the atmospheric lifetime of SO2F2. Further research is urgently needed to define the magnitude of potential nonatmospheric sinks. PMID:19320159

Andersen, M P Sulbaek; Blake, D R; Rowland, F S; Hurley, M D; Wallington, T J

2009-02-15

144

IR Window Studies.  

National Technical Information Service (NTIS)

This document describes the results of a variety to studies of IR window materials and systems performed at the University of Southern California during 1974-75. The studies fall under three categories: a) IR window material characterization, B) IR window...

F. A. Kroger J. H. Marburger

1975-01-01

145

Global sampling of the photochemical reaction paths of bromoform by ultrafast deep-UV through near-IR transient absorption and ab initio multiconfigurational calculations  

NASA Astrophysics Data System (ADS)

Ultrafast deep-ultraviolet through near infrared (210-950 nm) transient absorption spectroscopy complemented by ab initio multiconfigurational calculations offers a global description of the photochemical reaction pathways of bromoform following 255-nm excitation in methylcyclohexane and acetonitrile solutions. Photoexcitation of CHBr3 leads to the ground-state iso-CHBr3 product in a large quantum yield (~35%), formed through two different mechanisms: concerted excited-state isomerization and cage-induced isomerization through the recombination of the nascent radical pair. These two processes take place on different time scales of tens of femtoseconds and several picoseconds, respectively. The novel ultrafast direct isomerization pathway proposed herein is consistent with the occurrence of a conical intersection between the first excited singlet state of CHBr3 and the ground electronic state of iso-CHBr3. Complete active space self-consistent field calculations characterize this singularity in the vicinity of a second order saddle point on the ground state which connects the two isomer forms. For cage-induced isomerization, both the formation of the nascent radical pair and its subsequent collapse into ground-state iso-CHBr3 are directly monitored through the deep-ultraviolet absorption signatures of the radical species. In both mechanisms, the optically active (i.e., those with largest Franck-Condon factors) C-Br-Br bending and Br-Br stretching modes of ground-state iso-CHBr3 have the largest projection on the reaction coordinate, enabling us to trace the structural changes accompanying vibrational relaxation of the non-equilibrated isomers through transient absorption dynamics. The iso-CHBr3 photoproduct is stable in methylcyclohexane, but undergoes either facile thermal isomerization to the parent CHBr3 structure through a cyclic transition state stabilized by the polar acetonitrile medium (~300-ps lifetime), and hydrolysis in the presence of water.

Pal, S. K.; Mereshchenko, A. S.; Butaeva, E. V.; El-Khoury, P. Z.; Tarnovsky, A. N.

2013-03-01

146

Synthesis of 3,4-Dihydropyrimidin-2(1H)-Ones and Their Corresponding 2(1H)Thiones Using Trichloroacetic Acid as a Catalyst under Solvent-Free Conditions  

PubMed Central

Trichloroacetic acid was found to be a convenient catalyst for the synthesis of 3,4-dihydropyrimidin-2-(1H)-ones and their corresponding 2(1H)-thiones through a one-pot three-component reaction of aldehydes, alkyl acetoacetate, and urea or thiourea at 70°C under solvent-free conditions.

Karimi-Jaberi, Zahed; Moaddeli, Mohammad Sadegh

2012-01-01

147

Dynamics of the reactions of O(1D) with CD3OH and CH3OD studied with time-resolved Fourier-transform IR spectroscopy.  

PubMed

We investigated the reactivity of O((1)D) towards two types of hydrogen atoms in CH(3)OH. The reaction was initiated on irradiation of a flowing mixture of O(3) and CD(3)OH or CH(3)OD at 248 nm. Relative vibration-rotational populations of OH and OD (1 ? v ? 4) states were determined from their infrared emission recorded with a step-scan time-resolved Fourier-transform spectrometer. In O((1)D) + CD(3)OH, the rotational distribution of OD is nearly Boltzmann, whereas that of OH is bimodal; the product ratio [OH]/[OD] is 1.56 ± 0.36. In O((1)D) + CH(3)OD, the rotational distribution of OH is nearly Boltzmann, whereas that of OD is bimodal; the product ratio [OH]/[OD] is 0.59 ± 0.14. Quantum-chemical calculations of the potential energy and microcanonical rate coefficients of various channels indicate that the abstraction channels are unimportant and O((1)D) inserts into the C-H and O-H bonds of CH(3)OH to form HOCH(2)OH and CH(3)OOH, respectively. The observed three channels of OH are consistent with those produced via decomposition of the newly formed OH or the original OH moiety in HOCH(2)OH or decomposition of CH(3)OOH. The former decomposition channel of HOCH(2)OH produces vibrationally more excited OH because of incomplete intramolecular vibrational relaxation, and decomposition of CH(3)COOH produces OH with greater rotational excitation, likely due to a large torque angle during dissociation. The predicted [OH]/[OD] ratios are 1.31 and 0.61 for O((1)D) + CD(3)OH and CH(3)OD, respectively, at collision energy of 26 kJ mol(-1), in satisfactory agreement with the experimental results. These predicted product ratios vary weakly with collision energy. PMID:23126710

Huang, Chong-Kai; Xu, Zhen-Feng; Nakajima, Masakazu; Nguyen, Hue M T; Lin, M C; Tsuchiya, Soji; Lee, Yuan-Pern

2012-10-28

148

First synthesis of 3-acetyl-2-aminothiophenes using the Gewald reaction.  

PubMed

Novel 3-acetyl-2-aminothiophenes were prepared from cyanoacetone and 1,4-dithianyl-2,5-diols using a modified Gewald reaction. The syntheses of the corresponding acetamides, as well as that of 3-acetyl-2-amino-5-nitrothiophene - an interesting building-block for thiophene azo dyes - are reported. Detailed spectroscopic investigations ((1)H-NMR, (13)C-NMR, MS, IR) of the obtained compounds are presented. PMID:17962769

Eller, Gernot A; Holzer, Wolfgang

2006-05-16

149

Genetic Variation in Myosin 1H Contributes to Mandibular Prognathism  

PubMed Central

Introduction Several candidate loci have been suggested as influencing mandibular prognathism (1p22.1, 1p22.2, 1p36, 3q26.2, 5p13-p12, 6q25, 11q22.2-q22.3, 12q23, 12q13.13, and 19p13.2). The goal of this study was to replicate these results in a well-characterized homogeneous sample set. Methods Thirty-three single nucleotide polymorphisms spanning all candidate regions were studied in 44 prognathic and 35 Class I subjects from the University of Pittsburgh School of Dental Medicine Dental Registry and DNA Repository. The 44 mandibular prognathism subjects had an average age of 18.4 years, 31 were females and 13 males, and 24 were White, 15 African American, two Hispanic, and three Asian. The 35 Class I subjects had an average age of 17.6 years, 27 were females and 9 males, and 27 were White, six African Americans, one Hispanic, and two Asian. Skeletal mandibular prognathism diagnosis included cephalometric values indicative of Class III such as ANB smaller than two degrees, negative Witts appraisal, and positive A–B plane. Additional mandibular prognathism criteria included negative OJ and visually prognathic (concave) profile as determined by the subject's clinical evaluation. Orthognathic subjects without jaw deformations were used as a comparison group. Mandibular prognathism and orthognathic subjects were matched based on race, sex and age. Genetic markers were tested by polymerase chain reaction using TaqMan chemistry. Chi-square and Fisher exact tests were used to determine overrepresentation of marker allele with alpha of 0.05. Results An association was unveiled between a marker in MYO1H (rs10850110) and the mandibular prognathism phenotype (p=0.03). MYO1H is a Class-I myosin that is in a different protein group than the myosin isoforms of muscle sarcomeres, which are the basis of skeletal muscle fiber typing. Class I myosins are necessary for cell motility, phagocytosis and vesicle transport. Conclusions More strict clinical definitions may increase homogeneity and aid the studies of genetic susceptibility to malocclusions. We provide evidence that MYO1H may contribute to mandibular prognathism.

Tassopoulou-Fishell, Maria; Deeley, Kathleen; Harvey, Erika M.; Sciote, James; Vieira, Alexandre R.

2013-01-01

150

Practical Methylation Procedure for (1H)-1,2,4-Triazole (Preprint).  

National Technical Information Service (NTIS)

Conversion of (1H)-1,2,4-triazole to its sodium salt with methanolic sodium methoxide is followed by reaction with iodomethane. A scalable approach that overcomes problems associated with water-soluble starting material and water-soluble product combined ...

J. L. Belletire R. A. Bills S. A. Shackelford

2007-01-01

151

Practical Methylation Procedure for (1H)-1,2,4-Triazole (Postprint).  

National Technical Information Service (NTIS)

Conversion of (1H)-1,2,4-triazole to its sodium salt with methanolic sodium methoxide is followed by reaction with iodomethane. A scalable approach that overcomes problems associated with water-soluble starting material and water-soluble product combined ...

J. L. Belletire R. A. Bills S. A. Shackelford

2007-01-01

152

Synthesis of 5-substituted-1H-indol-2-yl-1H-quinolin-2-ones: a novel class of KDR kinase inhibitors.  

PubMed

[reaction: see text] A number of approaches for the synthesis of the 1H-indol-2-yl-1H-quinolin-2-one ring system found in the potent and selective KDR kinase inhibitor 1 are described. The preparation and reaction of trimethylsilylnitrobenzene 26 with 2-methoxy-3-quinolinecarboxaldehyde 28 afforded alcohol 30, which was the key intermediate for the preparation of the target compounds. Conversion of alcohol 30 to either nitroketone 36 or nitrostyrene 45 set the stage for reductive cyclization and the formation of indole 25. The quinolin-2-one functionality was unmasked in the last step to provide compound 1 in 56-60% overall yield from readily available starting materials. PMID:15787543

Kuethe, Jeffrey T; Wong, Audrey; Qu, Chuanxing; Smitrovich, Jacqueline; Davies, Ian W; Hughes, David L

2005-04-01

153

Structural and spectroscopic characterization of 2-mesityl-1H-benzo[d]imidazol-3-ium chloride: a combined experimental and theoretical analysis.  

PubMed

The title molecular salt, 2-mesityl-1H-benzo[d]imidazol-3-ium chloride (C(16)H(17)N(2)(+)·Cl-), was synthesized unexpectedly from the reaction of N-[(1E)-mesitylmethylene]benzene-1,2-diamine and CoCl(2)·6H(2)O, and characterized by elemental analysis, (1)H NMR and FT-IR spectroscopies, and single-crystal X-ray diffraction technique. In addition, quantum chemical calculations employing density functional theory (DFT) method with the 6-311++G(d,p) basis set were performed to study the molecular, spectroscopic and some electronic structure properties of the title compound, and the results were compared with the experimental findings. The computational result shows that the optimized geometry can well reproduce the crystal structural parameters. The intermolecular proton transfer process between the ionic (C(16)H(17)N(2)(+)·Cl-) and nonionic forms (C(16)H(16)N(2)·HCl) of the title salt is investigated and found to be almost barierless with an energy value of 0.20 kcal mol(-1). The NLO properties of the compound are bigger than those of urea. PMID:22366614

Özdemir, Nam?k

2012-02-04

154

Analysis of 1H/2H exchange kinetics using model infrared spectra.  

PubMed

This paper investigates the different approaches that best retrieve band shape parameters and kinetic time constants from series of protein Fourier transform infrared (FT-IR) spectra recorded in the course of 1H/2H exchange. In this first approach, synthetic spectra were used. It is shown that 1H/2H exchange kinetic measurements can help resolve spectral features otherwise hidden because of the overlap of various spectral contributions. We evaluated the efficiency of Fourier self-deconvolution, synchronous/asynchronous correlation, difference spectroscopy, principal component analysis, inverse Laplace transform, and determination of the underlying spectra by global analysis assuming first-order kinetics with either known or unknown time constants. It is demonstrated that some strategies allow the extraction of both the time dependence and the spectral shape of the underlying contributions. PMID:14727723

Raussens, Vincent; Ruysschaert, Jean-Marie; Goormaghtigh, Erik

2004-01-01

155

Synthesis and Supramolecular Structure of a (5-(3-(1H-tetrazol-5-yl)phenyl)-1H-tetrazole) Cobalt Complex  

PubMed Central

The reaction of CoCl2·6H2O with m-BDTH2 (1,3-benzeneditetrazol-5-yl) leads to [Co(C8H6N8)2(H2O)2(CH3CN)2]Cl2 (1). Both tetrazolic groups remain protonated existing in a 1H tautomeric form. A trifurcated chlorine atom and stacking interactions assemble compound 1 into a three-dimensional network.

Kostakis, George E.; Anson, Christopher E.; Powell, Annie K.

2010-01-01

156

IOT Overview: IR Instruments  

Microsoft Academic Search

In this instrument review chapter the calibration plans of ESO IR instruments are presented and briefly reviewed focusing,\\u000a in particular, on the case of ISAAC, which has been the first IR instrument at VLT and whose calibration plan served as prototype\\u000a for the coming instruments.

E. Mason

2008-01-01

157

Reactions of lithiated P-diphenyl(alkyl)( N-methoxycarbonyl)phosphazenes with Michael acceptors and aldehydes. Synthesis of 1 H-1,2-azaphosphinin-6-ones, ?-hydroxy( N-methoxycarbonyl)phosphazenes and 5,6-dihydro-1,3,4-oxazaphosphinin-2-ones  

Microsoft Academic Search

Lithium (N-methoxycarbonyl)phosphazenes add C-regioselectively to DMAD, dimethyl malonate, fumarate, and butylidenmalonate in a [1,4] manner. Only one diastereoisomer is observed with the olefinic electrophiles. With DMAD the initial adduct evolves through cyclocondensation with the CO2Me group of the phosphazene and 1H-1,2-azaphosphinin-6-ones are obtained. Exceptionally, methyl phenylpropiolate reacted exclusively through the carbonyl yielding a mixture of C- and N-acylated compounds. The

Julia M Álvarez-Gutiérrez; Emma Peralta-Pérez; Isidro Pérez-Álvarez; Fernando López-Ortiz

2001-01-01

158

WebSpectra: Problems in NMR and IR Spectroscopy  

NSDL National Science Digital Library

From the University of California at Los Angeles's Chemistry Department, WebSpectra provides chemistry students with a searchable library of Nuclear Magnetic Resonance (NMR) and Infrared (IR) spectroscopy problems. According to the makers of this innovative site, "Interpretation of spectra is a technique that requires practice - this site provides 1H NMR and 13C NMR, DEPT, COSY and IR spectra of various compounds for students to interpret." A set of instructional documents are entitled Solving Spectral Problems, Overview of NMR Spectroscopy, Notes on NMR Solvents, Types of NMR Spectra, Introduction to IR Spectra, and a Table of IR Absorptions. A wide variety of compounds and their spectra are available for interpretation and have been organized in categories from Beginning to Advanced. Spectrum for each compound may be magnified 16X by clicking on peaks. This is an outstanding learning tool for students coming to grips with interpreting NMR and IR spectra.

159

Synthesis, spectroscopic properties and crystal structure determination of 2-(2-pyridin-4-yl-vinyl)-1 H -benzimidazole derivatives  

Microsoft Academic Search

Substituted 2-(2-pyridin-4-yl-vinyl)-1H-benzimidazole derivatives 2, 3 and 6 were synthesized. 2-(2-Pyridin-4-yl-vinyl)-1H-benzimidazole 2 and 6-methyl-2-(2-pyridin-4-yl-vinyl)-1H-benzimidazole 3 were prepared by condensation reaction from 3-pyridin-4-yl-acrylic acid and corresponding 1,2-phenylenediamines in polyphosporic\\u000a acid (PPA). 2,7,11-b-Triaza-benzo[c]fluorene 4 was prepared by photochemical dehydrocyclization reaction of ethanolic solution of 2-(2-pyridin-4-yl-vinyl)-1H-benzimidazole 2. 2-(2-Pyridin-4-yl-vinyl)-3H-benzimidazole-6-carbonitrile 6 was prepared by condensation reaction from 3-pyridin-4-yl-propenal and 4-cyano-1,2-phenylenediamine using p-benzoquinone as oxidants. The structure

Marijana Hranjec; Gordana Pavlovi?; Marinela Marinovi?; Grace Karminski-Zamola

2008-01-01

160

Isolation and characterization of 3-[(carboxymethyl)thio]-3-(1H-imidazol-4-yl)propanoic acid from human urine and preparation of its proposed precursor, S-[2-carboxy-1-(1H-imidazol-4-yl)ethyl]cysteine.  

PubMed Central

3-[(Carboxymethyl)thio]-3-(1H-imidazol-4-yl)propanoic acid (I) was isolated from healthy human urine by using ion-exchange column chromatography, and characterized by physicochemical analyses involving i.r., m.s. and n.m.r. spectrometries as well as chemical synthesis. The urinary content was 0.04-0.07 mumol/l. Compound (I) was synthesized by the addition of mercaptoacetic acid to urocanic acid. In order to establish the origin of the compound. S-[2-carboxy-1-(1H-imidazol-4-yl)ethyl]cysteine (II) and S-[2-carboxy-1-(1H-imidazol-4-yl)ethyl]glutathione (III) were produced by similar reactions of urocanic acid with cysteine and GSH respectively. The yield of compound (II) was markedly increased by sunlight irradiation of the reaction mixture or by the use of cis-urocanic acid rather than the trans isomer. Incubation of compound (II) with rat liver homogenate in a phosphate buffer, pH 7.40, formed a major and some minor products of enzymic degradation, one of which was identified with compound (I). Exposure of rats to the sunlight for 2 days resulted in increase of the epidermal content of trans-urocanic acid from the normal value of 0.38 to 1.70 micrograms/mg wet wt. of skin, accompanied by formation de novo of the epidermal cis isomer. After sunlight irradiation, the content of the trans isomer decreased at a constant rate of 0.03 micrograms/mg wet wt. of skin per day, whereas the cis isomer was eliminated more quickly, having a phase of rapid decrease in the early period. From these results we suggest that compound (I) may participate in the metabolism of urocanic acid and natural thiol compounds such as cysteine and GSH.

Kinuta, M; Yao, K; Masuoka, N; Ohta, J; Teraoka, T; Ubuka, T

1991-01-01

161

Insulin receptor substrate 3 (IRS-3) and IRS-4 impair IRS-1- and IRS-2-mediated signaling.  

PubMed

To investigate the roles of insulin receptor substrate 3 (IRS-3) and IRS-4 in the insulin-like growth factor 1 (IGF-1) signaling cascade, we introduced these proteins into 3T3 embryonic fibroblast cell lines prepared from wild-type (WT) and IRS-1 knockout (KO) mice by using a retroviral system. Following transduction of IRS-3 or IRS-4, the cells showed a significant decrease in IRS-2 mRNA and protein levels without any change in the IRS-1 protein level. In these cell lines, IGF-1 caused the rapid tyrosine phosphorylation of all four IRS proteins. However, IRS-3- or IRS-4-expressing cells also showed a marked decrease in IRS-1 and IRS-2 phosphorylation compared to the host cells. This decrease was accounted for in part by a decrease in the level of IRS-2 protein but occurred with no significant change in the IRS-1 protein level. IRS-3- or IRS-4-overexpressing cells showed an increase in basal phosphatidylinositol 3-kinase activity and basal Akt phosphorylation, while the IGF-1-stimulated levels correlated well with total tyrosine phosphorylation level of all IRS proteins in each cell line. IRS-3 expression in WT cells also caused an increase in IGF-1-induced mitogen-activated protein kinase phosphorylation and egr-1 expression ( approximately 1.8- and approximately 2.4-fold with respect to WT). In the IRS-1 KO cells, the impaired mitogenic response to IGF-1 was reconstituted with IRS-1 to supranormal levels and was returned to almost normal by IRS-2 or IRS-3 but was not improved by overexpression of IRS-4. These data suggest that IRS-3 and IRS-4 may act as negative regulators of the IGF-1 signaling pathway by suppressing the function of other IRS proteins at several steps. PMID:11113178

Tsuruzoe, K; Emkey, R; Kriauciunas, K M; Ueki, K; Kahn, C R

2001-01-01

162

Web Spectra: Problems in NMR and IR spectroscopy  

NSDL National Science Digital Library

This site was established to provide chemistry students with a library of spectroscopy problems. Interpretation of spectra is a technique that requires practice - this site provides 1H NMR and 13 C NMR, DEPT, COSY and IR spectra of various compounds for students to interpret. Hopefully, these problems will provide a useful resource to better understand spectroscopy.

Merlic, Craig A.

2008-02-29

163

Lipoatrophic diabetes in Irs1(-/-)/Irs3(-/-) double knockout mice.  

PubMed

Based on the phenotypes of knockout mice and cell lines, as well as pathway-specific analysis, the insulin receptor substrates IRS-1, IRS-2, IRS-3, and IRS-4 have been shown to play unique roles in insulin signal transduction. To investigate possible functional complementarity within the IRS family, we generated mice with double knockout of the genes for IRS-1/IRS-3 and IRS-1/IRS-4. Mice with a combined deficiency of IRS-1 and IRS-4 showed no differences from Irs1(-/-) mice with respect to growth and glucose homeostasis. In contrast, mice with a combined deficiency of IRS-1 and IRS-3 developed early-onset severe lipoatrophy associated with marked hyperglycemia, hyperinsulinemia, and insulin resistance. However, in contrast to other models of lipoatrophic diabetes, there was no accumulation of fat in liver or muscle. Furthermore, plasma leptin levels were markedly decreased, and adenovirus-mediated expression of leptin in liver reversed the hyperglycemia and hyperinsulinemia. The results indicate that IRS-1 and IRS-3 play important complementary roles in adipogenesis and establish the Irs1(-/-)/Irs3(-/-) double knockout mouse as a novel model of lipoatrophic diabetes. PMID:12502742

Laustsen, Palle G; Michael, M Dodson; Crute, Barbara E; Cohen, Shmuel E; Ueki, Kohjiro; Kulkarni, Rohit N; Keller, Susanna R; Lienhard, Gustav E; Kahn, C Ronald

2002-12-15

164

Carbon–carbon coupling on tetrahedral iridium clusters: X-ray molecular structures and multinuclear NMR studies of the two isomeric forms of [Ir 4(CO) 6(? 3-? 2-HCCPh)(? 2-? 4-C 4H 2Ph 2)(?-PPh 2) 2  

Microsoft Academic Search

The reactions of [HIr4(CO)9(Ph2PCCPh)(?-PPh2)] (1) or [Ir4(CO)8(?3-?2-HCCPh)(?-PPh2)2] (2) with HCCPh gave two isomeric forms of [Ir4(CO)6(?3-?2-HCCPh)(?2-?4-C4H2Ph2)(?-PPh2)2] (3 and 4) in good yields as the only products. These compounds were characterized with analytical and spectroscopic data including 1H, 13C and 31P NMR (1 and 2D) spectroscopy and their molecular structures were established by X-ray diffraction studies. Compounds 3 and 4 exhibit

Maria Helena Araujo; Maria D. Vargas; Anthony G. Avent; Dario Braga; Fabrizia Grepioni

2004-01-01

165

Synthetic IR scene generation  

NASA Astrophysics Data System (ADS)

Testing sensor systems against accurate simulated laboratory data furnishes a higher level of confidence in actual flight test planning and evaluation of the test results. An account is presently given of an IR scene-generation model consisting of images from the AERIE terrain model, the ACM cloud model, and the SPIRITS target model. IR scene synthesis will be useful in studies of observables for air vehicle detection and for systems vulnerability analysis, as well as in sensor system evaluation.

Stets, J.; Conant, J.; Gruninger, J.; Ryali, B.

1988-01-01

166

Antitubercular activity of novel substituted 4,5-dihydro-1H-1-pyrazolylmethanethiones.  

PubMed

A series of, anilino-5-(substituted) phenyl-3-(4-hydroxy-3-methylphenyl)-4,5-dihydro-1H-1-pyrazolylmethanethione and 2-chloroanilino-5-(substituted) phenyl-3-(4-hydroxy-3-methylphenyl)-4,5-dihydro-1H-1-pyrazolylmethanethione were synthesized by the reaction between hydrazine hydrate and the chalcones (3a-k) followed by condensation with the appropriate aryl isothiocyanate which yielded the N-substituted pyrazoline derivatives. These were tested for their in-vitro anti-mycobacterial activity against INH resistant Mycobacterium tuberculosis (INHR MTB) using the BACTEC 460 radiometric system. Compound 2-chloroanilino-5-(2,6-dichlorophenyl)-3-(4-hydroxy-3-methylphenyl)-4,5-dihydro-1H-1-pyrazolyl-methanethione (6i) was found to be most active agent with a minimum inhibitory concentration of 0.96 microg/mL. PMID:17518345

Ali, Mohamed Ashraf; Yar, Mohammad Shahar

2007-04-01

167

Copper-Catalyzed Arylation of 1H-Perfluoroalkanes  

PubMed Central

A general method has been developed for arylation of readily available 1H-perfluoroalkanes. The method employs aryl iodide and 1H-perfluoroalkane reagents, DMPU solvent, TMP2Zn base, and a copper chloride/phenanthroline catalyst. Preliminary mechanistic studies are reported.

Popov, Ilya; Lindeman, Sergey; Daugulis, Olafs

2011-01-01

168

Copper-catalyzed arylation of 1H-perfluoroalkanes.  

PubMed

A general method has been developed for arylation of readily available 1H-perfluoroalkanes. The method employs aryl iodide and 1H-perfluoroalkane reagents, DMPU solvent, TMP(2)Zn base, and a copper chloride/phenanthroline catalyst. Preliminary mechanistic studies are reported. PMID:21627068

Popov, Ilya; Lindeman, Sergey; Daugulis, Olafs

2011-05-31

169

IrO2-deposited Pt electrocatalysts for unitized regenerative polymer electrolyte fuel cells  

Microsoft Academic Search

An IrO2\\/Pt electrocatalyst for the polymer electrolyte-type unitized regenerative fuel cell (URFC) was prepared by deposition of iridium oxide (IrO2) particles on Pt black via a colloidal iridium hydroxide hydrate precursor, and URFC performance was examined. After the iridium hydroxide hydrate deposited Pt was calcined at 400 °C in air for 1 h, rutile-structure IrO2 particles (20–50 nm dia.) were

T. Ioroi; N. Kitazawa; K. Yasuda; Y. Yamamoto; H. Takenaka

2001-01-01

170

Predicted NO2 IR chemiluminescence in the natural atmosphere  

NASA Astrophysics Data System (ADS)

Results from the author's recent theoretical study of NO2 IR Chemiluminescence from the NO + 0 and NO + 03 reactions are employed in a new upper atmospheric NO2 IR radiance model. Predictions are made for altitude dependent and column-integrated NO2 chemiluminescent radiance in four vibrational bands, and comparison is made with previous model predictions.

Adler-Golden, S.

1986-05-01

171

Measurement of (1)H-(15)N and (1)H-(13)C residual dipolar couplings in nucleic acids from TROSY intensities.  

PubMed

Analogous to the recently introduced ARTSY method for measurement of one-bond (1)H-(15)N residual dipolar couplings (RDCs) in large perdeuterated proteins, we introduce methods for measurement of base (13)C-(1)H and (15)N-(1)H RDCs in protonated nucleic acids. Measurements are based on quantitative analysis of intensities in (1)H-(15)N and (13)C-(1)H TROSY-HSQC spectra, and are illustrated for a 71-nucleotide adenine riboswitch. Results compare favorably with those of conventional frequency-based measurements in terms of completeness and convenience of use. The ARTSY method derives the size of the coupling from the ratio of intensities observed in two TROSY-HSQC spectra recorded with different dephasing delays, thereby minimizing potential resonance overlap problems. Precision of the RDC measurements is limited by the signal-to-noise ratio, S/N, achievable in the 2D TROSY-HSQC reference spectrum, and is approximately given by 30/(S/N) Hz for (15)N-(1)H and 65/(S/N) Hz for (13)C-(1)H. The signal-to-noise ratio of both (1)H-(15)N and (1)H-(13)C spectra greatly benefits when water magnetization during the experiments is not perturbed, such that rapid magnetization transfer from bulk water to the nucleic acid, mediated by rapid amino and hydroxyl hydrogen exchange coupled with (1)H-(1)H NOE transfer, allows for fast repetition of the experiment. RDCs in the mutated helix 1 of the riboswitch are compatible with nucleotide-specifically modeled, idealized A-form geometry and a static orientation relative to the helix 2/3 pair, which differs by ca 6° relative to the X-ray structure of the native riboswitch. PMID:21947918

Ying, Jinfa; Wang, Jinbu; Grishaev, Alex; Yu, Ping; Wang, Yun-Xing; Bax, Ad

2011-09-27

172

Measurement of 1H-15N and 1H-13C residual dipolar couplings in nucleic acids from TROSY intensities  

PubMed Central

Analogous to the recently introduced ARTSY method for measurement of one-bond 1H-15N residual dipolar couplings (RDCs) in large perdeuterated proteins, we introduce methods for measurement of base 13C-1H and 15N-1H RDCs in protonated nucleic acids. Measurements are based on quantitative analysis of intensities in 1H-15N and 13C-1H TROSY-HSQC spectra, and are illustrated for a 71-nucleotide adenine riboswitch. Results compare favorably with those of conventional frequency-based measurements in terms of completeness and convenience of use. The ARTSY method derives the size of the coupling from the ratio of intensities observed in two TROSY-HSQC spectra recorded with different dephasing delays, thereby minimizing potential resonance overlap problems. Precision of the RDC measurements is limited by the signal-to-noise ratio, S/N, achievable in the 2D TROSY-HSQC reference spectrum, and is approximately given by 30/(S/N) Hz for 15N-1H and 65/(S/N) Hz for 13C-1H. The signal-to-noise ratio of both 1H-15N and 1H-13C spectra greatly benefits when water magnetization during the experiments is not perturbed, such that rapid magnetization transfer from bulk water to the nucleic acid, mediated by rapid amino and hydroxyl hydrogen exchange coupled with 1H-1H NOE transfer, allows for fast repetition of the experiment. RDCs in the mutated helix 1 of the riboswitch are compatible with nucleotide-specifically modeled, idealized A-form geometry and a static orientation relative to the helix 2/3 pair, which differs by ca 6° relative to the X-ray structure of the native riboswitch.

Ying, Jinfa; Wang, Jinbu; Grishaev, Alex; Yu, Ping; Wang, Yun-Xing; Bax, Ad

2011-01-01

173

Ethyl 2-{[5-(3-chloro-phen-yl)-1-phenyl-1H-pyrazol-3-yl]-oxy}acetate  

PubMed Central

The title compound, C19H17ClN2O3, was synthesized by the reaction of 5-(3-chloro­phen­yl)-1-phenyl-1H-pyrazol-3-ol and ethyl 2-bromo­acetate. In the crystal, the C- and N-linked benzene rings are twisted by 45.15?(3) and 53.55?(3)°, respectively, from the plane of the bridging 1H-pyrazole ring.

Yang, Xiao-Li

2012-01-01

174

Synthesis of 4Alkynyl Substituted 3,4-Dihydropyrimidin-2(1H)-Ones  

Microsoft Academic Search

4-Alkynyl-3,4-dihydropyrimidin-2-(1H)-ones were synthesized by one-pot reaction of propynals, ethyl acetoacetate and urea. The yields of acetylenic dihydropyrimidinones depend significantly upon the propynal structure and catalyst type. Comparative study of the catalysts nature revealed an important advantage of polyphosphate ester in THF in comparison with hydrochloric acid in methanol or trimethylchlorosilane in DMF allowing the preparation of target compounds in good

Vladimir V. Novokshonov; Irina A. Novokshonova; Hien T. T. Nguyen; Alevtina S. Medvedeva

2012-01-01

175

1H + 2H radiative capture and the 3He d-state  

NASA Astrophysics Data System (ADS)

The tensor analyzing power of the reaction 1H(d, ?)3He has been measured at ?cm = 96° and deuteron energies of 29.2 and 45.3 MeV. It arises from the interference of the transitions to the 3He S- and D-states and allows a selective check of the D-state wave function. The experimental result is compared to a Faddeev calculation treating both continuum and bound states exactly.

Jourdan, J.; Baumgartner, M.; Burzynski, S.; Egelhof, P.; Klein, A.; Pickar, M. A.; Plattner, G. R.; Ramsay, W. D.; Roser, H. W.; Sick, I.; Torre, J.

1985-11-01

176

Airworthiness Evaluation NUH-1H Helicopter with Global Positioning System.  

National Technical Information Service (NTIS)

The United States Army Aviation Engineering Flight Activity conducted a limited airworthiness flight evaluation of an NUH-1H helicopter in which a prototype global positioning system (GPS) was installed. Flight tests were conducted at Edwards Air Force Ba...

C. L. Thomas T. P. Benson

1977-01-01

177

Models of Far-IR Sources at W3-IRS4 and W3-IRS5.  

National Technical Information Service (NTIS)

Far-IR continuum maps made with the KAO of W3 at 47 and 95 micrometers show peaks identified with the mid-IR sources IRS4 and IRS5 and extended emission identified with the radio source W3A. We have taken the steepest radial scan profiles from the peaks a...

M. F. Campbell M. B. Campbell H. M. Butner D. F. Lester P. M. Harvey

1995-01-01

178

Thermodynamic Properties of Ir2S3 and IrS2.  

National Technical Information Service (NTIS)

Thermodynamic properties of Ir2S3 have been obtained from the equilibrium pressures of S2(g) measured by the effusion technique in the range of 920 to 1110 K. The standard Gibbs energy change at these temperatures for 2 Ir(s)+1.5 S2(g) = Ir2S3(s) was foun...

E. T. Chang N. A. Gokcen

1972-01-01

179

[1H and 13C NMR investigation of nifedipine].  

PubMed

1H-13C shift-shift correlation based assignment of the 13C and 1H NMR spectra of nifedipin are presented along with some results of MM+ and PM3 conformation analysis. Both computation methods yield asymmetric low energy conformers. MM+ molecular dynamics simulations give similar results. A lower limit to the interconversion rate of the asymmetric low energy conformers is determined using magnetic shielding differences obtained by TNDO/2 calculations. PMID:8714360

Kövesdi, I; Kapillerné, D R

1996-01-01

180

Syntheses of 5-substituted 1H-tetrazoles catalyzed by reusable CoY zeolite.  

PubMed

A simple and efficient route for the synthesis of 5-substituted 1H-tetrazoles catalyzed by CoY zeolite is reported. The salient features of this atom-economical, cost-effective, and high-yield cobalt-catalyzed protocol are aerobic conditions, lower reaction time, and milder reaction conditions without additives. Other advantages include experimental ease of manipulation, safer alternative to hazardous, corrosive, and polluting conventional Lewis acid catalysts, recovery, and reusability with consistent catalytic activity. The results are rationalized by proposing a suitable mechanism. PMID:21910486

Rama, Velladurai; Kanagaraj, Kuppusamy; Pitchumani, Kasi

2011-10-05

181

Integrated IR sensors  

Microsoft Academic Search

Integrated infrared (IR) sensors which exploit modular avionics concepts can provide features such as operational flexibility, enhanced stealthiness, and ease of maintenance to meet the demands of tactical, airborne sensor systems. On-board, tactical airborne sensor systems perform target acquisition, tracking, identification, threat warning, missile launch detection, and ground mapping in support of situation awareness, self-defense, navigation, target attack, weapon support,

Michael Tom; Edward Trujillo

1994-01-01

182

Nuclear IRS-1 and Cancer  

PubMed Central

The family of insulin receptor substrates (IRS) consists of four proteins (IRS-1 - IRS-4), which were initially characterized as typical cytosolic adaptor proteins involved in insulin receptor (IR) and insulin-like growth factor I receptor (IGF-IR) signaling. The first cloned and characterized member of the IRS family, IRS-1, has predicted molecular weight of 132 kDa, however, as a result of its extensive serine phosphorylation it separates on a SDS gel as a band of approximately 160–185 kDa. In addition to its metabolic and growth-promoting functions, IRS-1 is also suspected to play a role in malignant transformation. The mechanism by which IRS-1 supports tumor growth is not fully understood, and the argument that IRS-1 merely amplifies the signal from the IGF-1R and/or IR requires further investigation. Almost a decade ago, we reported the presence of nuclear IRS-1 in medulloblastoma clinical samples, which express viral oncoprotein, large T-antigen of human polyomavirus JC (JCV T-antigen). This first demonstration of nuclear IRS-1 was confirmed in several other laboratories. The nuclear IRS-1 was also detected by cells expressing the SV40 T-antigen, v-Src, in immortalized fibroblasts stimulated with IGF-I, in hepatocytes, 32D cells, and in an osteosarcoma cell line. More recently, nuclear IRS-1 was detected in breast cancer cells in association with estrogen receptor alpha (ER?), and in JC virus negative medulloblastoma cells expressing ER?, further implicating nuclear IRS-1 in cellular transformation. Here, we discuss how nuclear IRS-1 acting on DNA repair fidelity, transcriptional activity, and cell growth can support tumor development and progression.

Reiss, Krzysztof; Valle, Luis Del; Lassak, Adam; Trojanek, Joanna

2011-01-01

183

Nitration reaction modification of asphalt  

SciTech Connect

An experimental design was prepared to study the nitration reaction of asphalts at various concentrations by Fourier Transform Infrared Spectroscopy (FT-IR) and physical methods. After selection of a usable treatment level (1% by weight), the nitration reaction was performed on eight asphalts. These asphalts were evaluated by physical methods and for elastic recovery and by FT-IR.

Boucher, J.L.; Ihsiung Wang; Romine, R.A. (Southwestern Labs., Inc., Houston, TX (United States))

1990-07-01

184

The Incident Reporting System (IRS)  

Microsoft Academic Search

Instead of investigating accidents, Incident Reporting Systems (IRS) analyze in- cidents. Because incidents happen more often than accidents, larger samples can be obtained by collecting incident reports. Incident reports can be used to gain insight into the factors leading to failures. IRS have been successfully used in the aviation industry and in anesthesiology. This report discusses the use of IRS

Ilías Ortega

1999-01-01

185

Optical properties of Ir 2+-implanted silica glass  

Microsoft Academic Search

High-purity silica samples (OH content less than 1 ppm, impurity content less than 20 ppm) were implanted with 2 MeV Ir2+ ions at doses ranging from 0.6 to 7×1016ions\\/cm2, and annealed in air at 300°C, 600°C and 900°C for 1 h. An optical absorption band at 248 nm, associated with the presence of B2 defects, appears in the spectra of

J. C. Cheang-Wong; A. Oliver; J. Roiz; J. M. Hernández; L. Rodr??guez-Fernández; J. G. Morales; A. Crespo-Sosa

2001-01-01

186

Metabotyping of long-lived mice using 1H NMR spectroscopy.  

PubMed

Significant advances in understanding aging have been achieved through studying model organisms with extended healthy lifespans. Employing 1H NMR spectroscopy, we characterized the plasma metabolic phenotype (metabotype) of three long-lived murine models: 30% dietary restricted (DR), insulin receptor substrate 1 null (Irs1-/-), and Ames dwarf (Prop1df/df). A panel of metabolic differences were generated for each model relative to their controls, and subsequently, the three long-lived models were compared to one another. Concentrations of mobile very low density lipoproteins, trimethylamine, and choline were significantly decreased in the plasma of all three models. Metabolites including glucose, choline, glycerophosphocholine, and various lipids were significantly reduced, while acetoacetate, d-3-hydroxybutyrate and trimethylamine-N-oxide levels were increased in DR compared to ad libitum fed controls. Plasma lipids and glycerophosphocholine were also decreased in Irs1-/- mice compared to controls, as were methionine and citrate. In contrast, high density lipoproteins and glycerophosphocholine were increased in Ames dwarf mice, as were methionine and citrate. Pairwise comparisons indicated that differences existed between the metabotypes of the different long-lived mice models. Irs1-/- mice, for example, had elevated glucose, acetate, acetone, and creatine but lower methionine relative to DR mice and Ames dwarfs. Our study identified several potential candidate biomarkers directionally altered across all three models that may be predictive of longevity but also identified differences in the metabolic signatures. This comparative approach suggests that the metabolic networks underlying lifespan extension may not be exactly the same for each model of longevity and is consistent with multifactorial control of the aging process. PMID:22225495

Wijeyesekera, Anisha; Selman, Colin; Barton, Richard H; Holmes, Elaine; Nicholson, Jeremy K; Withers, Dominic J

2012-02-27

187

Stable Ir/SiO2 catalyst for selective hydrogenation of crotonaldehyde  

NASA Astrophysics Data System (ADS)

Vapor-phase selective hydrogenation of crotonaldehyde was conducted over Ir/SiO2 catalysts to investigate the effects of Ir loading on the catalytic behaviors. The catalysts were characterized by X-ray powder diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), CO chemisorption, temperature-programmed reduction (TPR), diffuse reflectance infrared Fourier transform spectra of CO adsorption (CO-DRIFTS), NH3 temperature-programmed desorption (NH3-TPD), and temperature-programmed oxidation (TPO). It was found that the particle size of Ir in the catalyst increased with Ir loading, being 2.1, 3.9 and 6.7 nm for the 1Ir/SiO2, 3Ir/SiO2 and 5Ir/SiO2 catalyst, respectively. The Ir species on the Ir/SiO2 catalysts consisted of Ir0 and Ir?+, but the average valence of Ir species decreased with increasing Ir loading. Also, catalytic testing results revealed that the reactivity of the catalyst increased with Ir loading. Interestingly, it was found that the reaction underwent an induction period, with the conversion of crotonaldehyede and the selectivity to crotyl alcohol gradually increasing during the reaction, and eventually reaching a steady state. The highest selectivity (77.6%) to crotyl alcohol was obtained over the 3Ir/SiO2 catalyst, and the conversion increased gradually to 15.6%. The catalytic behavior of these stable catalysts could be attributed to the proper Ir particle size, the existence of Ir0 and Ir?+ species on the surface, and high amount of surface acid sites in these catalysts.

Hong, Xiao; Li, Bo; Wang, Yuejuan; Lu, Jiqing; Hu, Gengshen; Luo, Mengfei

2013-04-01

188

Absolute configuration of amino alcohols by 1H-NMR.  

PubMed

A general NMR spectroscopy protocol for determination of absolute configuration of 1,2-amino alcohols, that allows differentiation of the four possible stereoisomers by analysis of the 1H NMR spectra of their bis-MPA derivatives, is described. PMID:16358061

Leiro, Victoria; Freire, Félix; Quiñoá, Emilio; Riguera, Ricardo

2005-10-06

189

The influence of a 1 h nap on performance overnight  

Microsoft Academic Search

The effect on performance overnight of a 1 h nap taken at 0200 h was studied in six young female subjects. The subjects completed three schedules, including one with a nap and two without a nap, during which either a placebo or 300 mg caffeine was ingested at 2315 h. Performance was measured from 1700 h in the evening until

A. S. ROGERS; M. B. SPENCER; B. M. STONE; A. N. NICHOLSON

1989-01-01

190

1H NMR analysis of sporopollenin from Typha Angustifolia  

Microsoft Academic Search

The first analysis of sporopollenin using 1H NMR-techniques revealed the presence of four phenolic compounds in different amounts. The phenolic compounds are tri- or tetrasubstituted. The sporopollenin was isolated and purified from Typha angustifolia by an enzymatic procedure, followed by extraction with organic solvents.

Friedhelm Ahlers; Ina Thom; Jörg Lambert; Rüdiger Kuckuk; Rolf Wiermann

1999-01-01

191

Vibrational analyses of 1,3-dibenzoyl-4,5-dihydro-1H-imidazole-2-thione and 1,3-dibenzoyl tetrahydropyrimidine-2(1H)-thione by normal coordinate treatment.  

PubMed

Vibrational analyses of 1,3-dibenzoyl-4,5-dihydro-1H-imidazole-2-thione and 1,3-dibenzoyl tetrahydropyrimidine-2(1H)-thione were carried out using normal coordinate analysis. FT-IR spectra were recorded in the region 4000-400 cm(-1). The harmonic vibrational frequencies, molecular geometry and atomic charges have been computed, and NBO analysis has been carried out with the help of B3LYP density functional theory (DFT). The computed geometrical bond lengths and bond angles agree well with the crystallographic data. Atomic charges based on Mulliken population analysis, natural population analysis, Hirshfeld-I analysis and CHelpG analysis were calculated using the basis sets of 6-31G(*) and 6-31G(**). Stabilities of the two molecules were analyzed by means of natural bond orbital (NBO) analysis and delocalized ?-?(*) interactions. PMID:22995469

Gumus, Sedat; Sundius, Tom; Yilmaz, Veysel Turan

2012-08-27

192

New N?-alkylidene/cycloalkylidene derivatives of 5-methyl-3-phenyl-1H-indole-2-carbohydrazide: synthesis, crystal structure, and quantum mechanical calculations  

NASA Astrophysics Data System (ADS)

The condensation products of 5-methyl-3-phenyl-1H-indole-2-carbohydrazide (1) with 2-butanone, 3-pentanone and cyclopentanone were prepared. The adducts (2a-c) were characterized by microanalysis, UV, IR, 1H NMR, 13C NMR and EI mass spectrometry. 1H NMR spectra of 2a and 2b revealed rotational restriction about the C N bond in solution (DMSO-d6) and displayed double resonances associated with the CH3 and CH2CH3 residues of the alkylidene moieties. A variable temperature 1H NMR experiment was run on 2a to overcome the rotational barriers and thus determine the coalescence temperature but no coalescence was observed up to 77 °C. The structural analysis of 2a and 2c were also carried out by single crystal X-ray diffraction and confirmed by theoretical calculations (semiempirical PM3 and ab initio RHF/6-31G(d)).

Kaynak, F. Betül; Öztürk, Devrim; Özbey, Süheyla; Çapan, Gültaze

2005-04-01

193

Synthesis and biological activity evaluation of 1 H-benzimidazoles via mammalian DNA topoisomerase I and cytostaticity assays  

Microsoft Academic Search

Benzimidazoles are important compounds because of their antibacterial, antifungal, antimicrobial, antiprotozoal and antihelmintic activities. Some benzimidazole derivatives also interfere with the reactions of DNA topoisomerases, enzymes functioning at almost all stages of the cell cycle. In this study, nine 1H-benzimidazole derivatives with substituents at positions 2 and 5 were synthesized and the structure of the compounds was elucidated by instrumental

Gunes Coban; Sevil Zencir; István Zupkó; Borbála Réthy; H. Semih Gunes; Zeki Topcu

2009-01-01

194

M(HSO4)n-Promoted Synthesis of 2Aryl1-arylmethyl-1H-1,3-benzimidazole Derivatives  

Microsoft Academic Search

We have developed a highly selective synthesis of 2-aryl-1-arylmethyl-1H-1,3-benzimidazoles from the reaction of o-phenylenediamines and aromatic aldehydes in the presence of metal hydrogen sulfates [M(HSO4)n] in water and also under solvent-free conditions in good to excellent yields.

Khodabakhsh Niknam; Mohammad Ali Zolfigol; Negar Safikhani

2008-01-01

195

IR Earth Flats Pathfinder  

NASA Astrophysics Data System (ADS)

This program is an experimental path finder for Cycle 18 calibration. {The WFC3 UVIS version of this is program 11914 and contains additional detail in its description}. Infrared-wavelength flat fields will be obtained by observing the dark side of the Earth during periods of full moon illumination. The observations will consist of full-frame streaked WFC3 IR imagery: per single "dark-sky" orbit, we anticipate achieving Poisson S/N > 100 per pixel in each of three to five exposures, depending on sample sequence {SPARS25 or SPARS50}. Why not use the Sunlit Earth? It is too bright for WFC3 IR full-frame minimum exposure time of 3 sec. Similarly, for NICMOS the sunlit-Earth is too bright which saturates the detector too quickly and/or induces abnormal behaviors such as super-shading {Gilmore 1998, NIC 098-011}. In the narrowband IR filters the sunlit earth sometimes is faint enough to not saturate immediately, but based upon predictions {Cox et al. 1987 "Standard Astronomical Sources for HST: 6. Spatially Flat Fields."} and observations {Gilmore 1998}, we consider sunlit Earth unlikely to be successful unless it is twilight. Other possibilities? Cox et al.'s Section II.D addresses many other possible sources for flat fields, rejecting them for a variety of reasons. A remaining possibility would be the totally eclipsed moon. Such eclipses provide approximately 2 hours {1 HST orbit} of opportunity per year, so they are too rare to be generically useful. An advantage of the moon over the Earth is that the moon subtends less than 0.25 square degree, whereas the Earth subtends a steradian or more, so scattered light and light prior to the unshuttered exposure presents additional problems for the Earth. Also, we're unsure if HST can point 180 deg from the Sun.;

McCullough, Peter

2008-07-01

196

Synthesis, molecular structure and spectral analysis of ethyl 4-[(3,5-dinitrobenzoyl)-hydrazonomethyl]-3,5-dimethyl-1H-pyrrole-2-carboxylate: A combined experimental and quantum chemical approach  

NASA Astrophysics Data System (ADS)

A new hydrazone, ethyl 4-[(3,5-dinitrobenzoyl)-hydrazonomethyl]-3,5-dimethyl-1H-pyrrole-2-carboxylate (PDNBAH) has been synthesized and characterized by FT-IR, 1H NMR, UV-visible spectroscopy. All the quantum chemical calculations have been performed by density functional theory (DFT), using B3LYP functional and 6-31G(d,p) as basis set. The calculated and experimental wavenumber analyses confirm the existence of dimer of PDNBAH. The calculated binding energies of dimer using DFT and Bader's atoms in molecules (AIM) theory are -14.32 and -15.41 kcal/mol respectively. The intermolecular hydrogen bond energy of dimer due to the involvement of intermolecular hetero-nuclear double hydrogen bonds (Nsbnd H⋯Odbnd C) through pyrrolic Nsbnd H and Cdbnd O of ester is also calculated to be equal to -12.29 kcal/mol using AIM calculation. The strength and the nature of hydrogen bonding and weak interactions in dimer have been analyzed by AIM theory in detail. The presence of resonance assisted hydrogen bonds (RAHB) has been confirmed by calculated ellipticity parameters using AIM calculation. The calculated thermodynamic parameters show that the reaction is non spontaneous at room temperature. The local reactivity descriptors show that C(13) is most reactive site for nucleophilic attack.

Singh, R. N.; Verma, Divya; Kumar, Amit; Baboo, Vikas

2012-03-01

197

Synthesis, molecular structure and spectral analysis of ethyl 4-[(3,5-dinitrobenzoyl)-hydrazonomethyl]-3,5-dimethyl-1H-pyrrole-2-carboxylate: a combined experimental and quantum chemical approach.  

PubMed

A new hydrazone, ethyl 4-[(3,5-dinitrobenzoyl)-hydrazonomethyl]-3,5-dimethyl-1H-pyrrole-2-carboxylate (PDNBAH) has been synthesized and characterized by FT-IR, (1)H NMR, UV-visible spectroscopy. All the quantum chemical calculations have been performed by density functional theory (DFT), using B3LYP functional and 6-31G(d,p) as basis set. The calculated and experimental wavenumber analyses confirm the existence of dimer of PDNBAH. The calculated binding energies of dimer using DFT and Bader's atoms in molecules (AIM) theory are -14.32 and -15.41 kcal/mol respectively. The intermolecular hydrogen bond energy of dimer due to the involvement of intermolecular hetero-nuclear double hydrogen bonds (N-H···O=C) through pyrrolic N-H and C=O of ester is also calculated to be equal to -12.29 kcal/mol using AIM calculation. The strength and the nature of hydrogen bonding and weak interactions in dimer have been analyzed by AIM theory in detail. The presence of resonance assisted hydrogen bonds (RAHB) has been confirmed by calculated ellipticity parameters using AIM calculation. The calculated thermodynamic parameters show that the reaction is non spontaneous at room temperature. The local reactivity descriptors show that C(13) is most reactive site for nucleophilic attack. PMID:22208959

Singh, R N; Verma, Divya; Kumar, Amit; Baboo, Vikas

2011-12-06

198

Osmium(IV) complexes with 1H- and 2H-indazoles: Tautomer identity versus spectroscopic properties and antiproliferative activity  

PubMed Central

A one-pot synthesis of osmium(IV) complexes with two different tautomers of indazole, 1H-indazole and 2H-indazole, namely (H2ind)[OsIVCl5(2H-ind)] (1) and (H2ind)[OsIVCl5(1H-ind)] (2) is reported. Both compounds have been comprehensively characterized by NMR spectroscopy, ESI (electrospray ionization) mass spectrometry, electronic absorption spectroscopy, IR spectroscopy, cyclic voltammetry and tested for antiproliferative activity in vitro in three human cancer cell lines, CH1 (ovarian carcinoma), A549 (non-small cell lung cancer) and SW480 (colon carcinoma), as well as in vivo in a Hep3B SCID mouse xeno-transplantation model. 2H-Indazole tautomer stabilization in 1 has been confirmed by X-ray diffraction.

Buchel, Gabriel E.; Stepanenko, Iryna N.; Hejl, Michaela; Jakupec, Michael A.; Keppler, Bernhard K.; Heffeter, Petra; Berger, Walter; Arion, Vladimir B.

2012-01-01

199

Analysis of cold rolling oils by NMR and IR techniques  

SciTech Connect

A new technology has been developed based on infrared (IR) and nuclear magnetic resonance (NMR) spectroscopic techniques for the quantitation of various components in rolling oils without their prior separation. The IR method makes use of a curve-fitting approach in which the multicomponent mixtures with overlapping bands can be quantified without exhibiting isolated, characteristic frequencies for each component. Prior information about the nature and the type of the components in the mixture is the basic requirement for this method. NMR methodology involves the direct identification and quantitation of various components from their characteristic {sup 1}H, {sup 13}C and {sup 31}P-NMR chemical shift data. Both IR and NMR techniques have been successfully applied to nine component blends and commercial oils. 5 refs., 4 figs., 4 tabs.

Chopra, A.; Sastry, M.I.S.; Kapur, G.S.; Sarpal, A.S. [Indian Oil Corporation Limited, Faridabad (India)] [and others

1996-04-01

200

Observation of signature inversion in odd-odd 178Ir  

NASA Astrophysics Data System (ADS)

High spin states in 178Ir have been studied via the 152Sm(31P,5n ?)178Ir reaction through excitation functions, X- ? and ?-?-t coincidence measurements. According to the band structure characteristics and the measured intraband B( M1)/ B( E2) ratios, two rotational bands are identified and assigned to be associated with the ?h 9/2? ?i 13/2 and ?h 11/2? ?i 13/2 configurations, respectively. Both bands show the signature inversion feature.

Zhang, Y. H.; Hayakawa, T.; Oshima, M.; Toh, Y.; Katakura, J.; Hatsukawa, Y.; Matsuda, M.; Shinohara, N.; Ishii, T.; Kusakari, H.; Sugawara, M.; Komatsubara, T.

2000-07-01

201

Novel Fe3+-Based 1H MRI ?-Galactosidase Reporter Molecules**  

PubMed Central

There is increasing interest in the development of reporter agents to reveal enzyme activity in vivo using small animal imaging. We have previously demonstrated the feasibility of detecting lacZ gene activity using the commercially available 3,4-cyclohexenoesculetin-?-D-galactopyranoside (S-Gal™) as a 1H MRI reporter. Specifically, ?-galactosidase (?-gal) releases the aglycone, which forms an MR contrast-inducing paramagnetic precipitate in the presence of Fe3+. Contrast was primarily T2-weighted signal loss, but T1 effects were also observed. Since T1-contrast generally provides signal enhancement as opposed to loss, it appeared attractive to explore whether analogues could be generated with enhanced characteristics. We now report the design and successful synthesis of novel analogues together with characterization of 1H MRI contrast based on both T1 and T2 response to ?-gal activity in vitro for the lead agent.

Yu, Jian-Xin; Gulaka, Praveen K.; Liu, Li; Kodibagkar, Vikram D.; Mason, Ralph P.

2012-01-01

202

Derivatives of 1,5-diamino-1H-tetrazole: a new family of energetic heterocyclic-based salts.  

PubMed

1,5-Diamino-1H-tetrazole (2, DAT) can easily be protonated by reaction with strong mineral acids, yielding the poorly investigated 1,5-diaminotetrazolium nitrate (2a) and perchlorate (2b). A new synthesis for 2 is introduced that avoids lead azide as a hazardous byproduct. The reaction of 1,5-diamino-1H-tetrazole with iodomethane (7a) followed by the metathesis of the iodide (7a) with silver nitrate (7b), silver dinitramide (7c), or silver azide (7d) leads to a new family of heterocyclic-based salts. In all cases, stable salts were obtained and fully characterized by vibrational (IR, Raman) spectroscopy, multinuclear NMR spectroscopy, mass spectrometry, elemental analysis, X-ray structure determination, and initial safety testing (impact and friction sensitivity). Most of the salts exhibit good thermal stabilities, and both the perchlorate (2b) and the dinitramide (7c) have melting points well below 100 degrees C, yet high decomposition onsets, defining them as new (7c), highly energetic ionic liquids. Preliminary sensitivity testing of the crystalline compounds indicates rather low impact sensitivities for all compounds, the highest being that of the perchlorate (2b) and the dinitramide (7c) with a value of 7 J. In contrast, the friction sensitivities of the perchlorate (2b, 60 N) and the dinitramide (7c, 24 N) are relatively high. The enthalpies of combustion (Delta(c)H degrees ) of 7b-d were determined experimentally using oxygen bomb calorimetry: Delta(c)H degrees (7b) = -2456 cal g(-)(1), Delta(c)H degrees (7c) = -2135 cal g(-)(1), and Delta(c)H degrees (7d) = -3594 cal g(-)(1). The standard enthalpies of formation (Delta(f)H degrees ) of 7b-d were obtained on the basis of quantum chemical computations using the G2 (G3) method: Delta(f)H degrees (7b) = 41.7 (41.2) kcal mol(-)(1), Delta(f)H degrees (7c) = 92.1 (91.1) kcal mol(-)(1), and Delta(f)H degrees (7d) = 161.6 (161.5) kcal mol(-)(1). The detonation velocities (D) and detonation pressures (P) of 2b and 7b-d were calculated using the empirical equations of Kamlet and Jacobs: D(2b) = 8383 m s(-)(1), P(2b) = 32.2 GPa; D(7b) = 7682 m s(-)(1), P(7b) = 23.4 GPa; D(7c) = 8827 m s(-)(1), P(7c) = 33.6 GPa; and D(7d) = 7405 m s(-)(1), P(7d) = 20.8 GPa. For all compounds, a structure determination by single-crystal X-ray diffraction was performed. 2a and 2b crystallize in the monoclinic space groups C2/c and P2(1)/n, respectively. The salts of 7 crystallize in the orthorhombic space groups Pna2(1) (7a, 7d) and Fdd2 (7b). The hydrogen-bonded ring motifs are discussed in the formalism of graph-set analysis of hydrogen-bond patterns and compared in the case of 2a, 2b, and 7b. PMID:15934752

Gálvez-Ruiz, Juan Carlos; Holl, Gerhard; Karaghiosoff, Konstantin; Klapötke, Thomas M; Löhnwitz, Karolin; Mayer, Peter; Nöth, Heinrich; Polborn, Kurt; Rohbogner, Christoph J; Suter, Max; Weigand, Jan J

2005-06-13

203

Campath-1H therapy in refractory ocular inflammatory disease  

Microsoft Academic Search

BACKGROUNDStandard therapy for severe, immune mediated, ocular inflammation has significant side effects, and may fail to control the disease. T cell directed monoclonal antibody (mAb) therapy can provide long term remission of inflammatory disease in experimental models. The Campath-1H mAb was administered to patients with severe, refractory, ocular inflammation.METHODS10 patients with severe, refractory, non-infectious ocular inflammatory disease were treated with

Andrew D Dick; Paul Meyer; Teife James; John V Forrester; Geoff Hale; Herman Waldmann; John D Isaacs

2000-01-01

204

19F and 1H NMR spectra of halocarbons.  

PubMed

19F NMR chemical shifts and coupling constants are reported for 215 compounds. For 77 of these compounds, 1H NMR spectral data are also given. Long-range couplings, including 8J(F,F) and 5J(F,H), are reported. The complexity of halocarbon spectra owing to the presence of rotational isomers, asymmetric centers, long-range couplings, and chlorine isotope effects are illustrated, and the methods used for analyzing such complex spectra are briefly discussed. PMID:15137047

Foris, Anthony

2004-06-01

205

Liquid seaweed extracts identified using 1 H NMR profiles  

Microsoft Academic Search

Aqueous extracts of Ascophyllum nodosum and several other brown seaweeds are manufactured commercially and widely distributed for use on agricultural crops. The\\u000a increasingly regulated international trade in such products requires that they be standardized and defined to a degree not\\u000a previously required. We examined commercially available extracts using quantitative 1H NMR and principal components analysis (PCA) techniques. Extracts manufactured over

James S. Craigie; Shawna L. MacKinnon; John A. Walter

2008-01-01

206

Liquid seaweed extracts identified using 1 H NMR profiles  

Microsoft Academic Search

Aqueous extracts of Ascophyllum nodosum and several other brown seaweeds are manufactured commercially and widely distributed for use on agricultural crops. The\\u000a increasingly regulated international trade in such products requires that they be standardized and defined to a degree not\\u000a previously required. We examined commercially available extracts using quantitative 1H NMR and principal components analysis (PCA) techniques. Extracts manufactured over

James S. Craigie; Shawna L. MacKinnon; John A. Walter

207

Antitumor Activity of 6-(cyclohexylamino)-1, 3-dimethyl-5(2-pyridyl)furo[2,3-d]pyrimidine-2,4(1H,3H)-dione and Its Ti(IV), Zn(II), Fe(III), and Pd(II) Complexes on K562 and Jurkat Cell Lines  

PubMed Central

(6-(cyclohexylamino)-1,3-dimethyl-5(2-pyridyl)furo[2,3-d]pyrimidine-2,4(1H,3H)-dione) abbreviated as CDP was synthesized and characterized. Ti(IV), Zn(II), Fe(III), and Pd(II) metal complexes of this ligand are prepared by the reaction of salts of Ti(IV), Zn(II), Fe(III), and Pd(II) with CDP in acetonitrile. Characterization of the ligand and its complexes was made by microanalyses, FT-IR, 1H NMR, 13C NMR, and UV-Visible spectroscopy. All complexes were characterized by several techniques using elemental analysis (C, H, N), FT-IR, electronic spectra, and molar conductance measurements. The elemental analysis data suggest the stoichiometry to be 1:1 [M:L] ratio formation. The molar conductance measurements reveal the presence of 1:1 electrolytic nature complexes. These new complexes showed excellent antitumor activity against two kinds of cancer cells that are K562 (human chronic myeloid leukemia) cells and Jurkat (human T lymphocyte carcinoma) cells.

Shabani, Fahmideh; Ghammamy, Shahriar; Mehrani, Khayroallah; Teimouri, Mohammad Bagher; Soleimani, Masoud; Kaviani, Saeid

2008-01-01

208

Microscale Synthesis and 1H NMR Analysis of Tetraphenylporphyrins  

NASA Astrophysics Data System (ADS)

The synthesis of tetraphenylporphyrin, H2[TPP], and para-substituted tetraphenylporphyrins, H2[(p-X)4TPP], where X = CN, CH3, and OCH3, is easily accomplished using microscale glassware. The compounds are synthesized from inexpensive starting reagents. The synthesis of the porphyrins involves the condensation of pyrrole with the appropriate benzaldehydes, producing purple solids. It is accomplished within one 2 1/2 hour laboratory period. These porphyrin systems generate simple 1H NMR spectra. The compounds provide an excellent introduction into the effects that aromaticity and electron donating/withdrawing groups have on 1H NMR chemical shifts. The porphyrin ring systems' extensive electron "clouds" provide excellent examples of diamagnetic anisotropy due to the circulation of the electrons within their molecular orbitals. Furthermore, the 1H NMR spectra of the para-substituted compounds, H2[(p-X)4TPP], provide an excellent example of spin coupling systems (between the ortho and meta protons on the phenyl rings) with a range of Dv/J ratios.

Falvo, Raeanne E.; Mink, Larry M.; Marsh, Diane F.

1999-02-01

209

Acceptor (CF3)PCPH pincer reactivity with (PPh3)3Ir(CO)H.  

PubMed

The syntheses of Ir(I) and Ir(III) complexes incorporating the electron-withdrawing pincer ligand (1,3-C(6)H(4)(CH(2)P(CF(3))(2))(2)) ((CF(3))PCPH) with (PPh(3))(3)Ir(CO)H and subsequent chemistry are reported. Under ambient conditions, reaction of 1 equiv. (CF(3))PCPH with (PPh(3))(3)Ir(CO)H gave the mono-bridged complex [Ir(CO)(PPh(3))(2)(H)](2)(?-(CF(3))PCPH) (1). Reaction of (PPh(3))(3)Ir(CO)H with excess (CF(3))PCPH and MeI gave the doubly-bridged complex [Ir(CO)(PPh(3))(H)](2)(?-(CF(3))PCPH)(2) (2), whereas the tetrameric oligomer [Ir(CO)(PPh(3))(H)](4)(?-(CF(3))PCPH)(4) (2-sq) was obtained from a 1:1 ligand:metal mixture in benzene in the presence of excess MeI. At higher temperatures (165 °C) the reaction of (CF(3))PCPH with (PPh(3))(3)Ir(CO)H afforded the 5-coordinate Ir(I) complex ((CF(3))PCP)Ir(CO)(PPh(3)) (3). Complex 3 shows mild catalytic activity for the decarbonylation of 2-naphthaldehyde in refluxing diglyme (162 °C). PMID:21894332

Adams, Jeramie J; Arulsamy, Navamoney; Roddick, Dean M

2011-09-06

210

Determination of the composition of styrene, isoprene, butadiene terpolymer by IR attenuated total reflection (ATR) spectroscopy  

NASA Astrophysics Data System (ADS)

A rapid method for quantitative determination of the composition of statistical terpolymers of styrene, butadiene, and isoprene by IR attenuated total reflection (ATR) spectroscopy is described. A quantitative model is designed with the aid of 1 H NMR spectroscopy. This method does not require that the test samples be dissolved or their thickness be monitored precisely, and records the IR spectrum of the rubber rapidly (<5 min). It is easily reproduced and has good convergence. The relative error is less than 5 %.

Orlov, A. S.; Mashukov, V. I.; Rakitin, A. R.; Novikova, E. S.

2012-07-01

211

Experimental and computational studies on the tautomerism of N-substituted 3-amino-5-oxo-4-phenyl-1H-pyrazolo-1-carboxamides with antibacterial activity  

NASA Astrophysics Data System (ADS)

The tautomerism of N-substituted 3-amino-5-oxo-4-phenyl-1H-pyrazolo-1-carboxamides with antibacterial activity is studied with X-ray crystallography, IR, 1H and 13C NMR (including NOESY spectra) and quantum chemical calculations. It is found that the form with the keto group at position 5 is the preferred one in the crystalline state and in DMSO, although some fraction with the corresponding hydroxy group also occurs in both states. This finding was related to the antibacterial activity of the studied compounds as the energetic stabilization of the keto group may determine their proper hydrogen bond interactions with the bacterial enzyme.

Kaczor, Agnieszka A.; Wróbel, Tomasz; Karczmarzyk, Zbigniew; Wysocki, Waldemar; Mendyk, Ewaryst; Poso, Antti; Matosiuk, Dariusz; Pitucha, Monika

2013-11-01

212

Synthesis, crystal structure and photoluminescent behaviors of 3-(1H-benzotriazol-1-yl)-4-methyl-benzo[7,8]coumarin  

Microsoft Academic Search

A novel coumarin derivative containing an electron-transporting moiety (benzotriazole), 3-(1H-benzotriazol-1-yl)-4-methyl-benzo[7,8]coumarin (BMBC), was synthesized and characterized by element analysis, 1H NMR, FT-IR and UV–vis absorption spectra, TG-DTA and single crystal X-ray crystallography. Crystallographic data reveal a dihedral angle of 60.4° between the benzocoumarin and benzotriazole rings, which is attributed to the spatial hindrance of a 4-positioned methyl group. The photoluminescent behaviors

Tianzhi Yu; Yuling Zhao; Xiansheng Ding; Duowang Fan; Long Qian; Wenkui Dong

2007-01-01

213

IR Dark Current Monitor  

NASA Astrophysics Data System (ADS)

Analyses of ground test data showed that dark current signals are more reliably removed from science data using darks taken with the same exposure sequences as the science data, than with a single dark current image scaled by desired exposure time. Therefore, dark current images must be collected using all sample sequences that will be used in science observations. These observations will be used to monitor changes in the dark current of the WFC3-IR channel on a day-to-day basis, and to build calibration dark current ramps for each of the sample sequences to be used by GOs in Cycle 17. For each sample sequence/array size combination, a median ramp will be created and delivered to the calibration database system {CDBS}.;

Hilbert, Bryan

2008-07-01

214

Coherent IR radar technology  

NASA Astrophysics Data System (ADS)

Recent progress in the development of coherent IR radar equipment is reviewed, focusing on the Firepond laser radar installation and the more compact systems derived for it. The design and capabilities of Firepond as a long-range satellite-tracking device are outlined. The technological improvements necessary to make laser radar mobile are discussed: a lightweight, stable 5-10-W transmitter laser for both CW and pulsed operation, a 12-element HgCdTe detector array, an eccentric-pupil Ritchey-Chretien telescope, and a combination of near-field phase modification and anamorphic expansion to produce a fan beam of relatively uniform intensity. Sample images obtained with a prototype system are shown, and the applicability of the mobile system to range-resolved coherent DIAL measurement is found to be similar to that of a baseline DIAL system.

Gschwendtner, A. B.; Harney, R. C.; Hull, R. J.

215

Intense IR laser field  

SciTech Connect

Here, we present a new approach to simulate the molecular dissociation dynamics in strong IR laser field, which combines a quantum description of the dynamics of electronic states of a molecule and classical dynamics within a single electronic state. As an example, computer simulation results on HCl{sup +} dissociation in intense ({ital I}{approximately}10{sup 14} W/cm{sup 2}) laser field in two-level approximation are presented. The probabilities of different stable states of a molecule at the end of laser pulse are calculated. It is shown that molecule{close_quote}s dissociation dynamics in intense laser field has a quantum stochastic nature. It is argued that the used model can be applied to multiatomic molecules as well. {copyright} {ital 1996 American Institute of Physics.}

Grishanin, B.A.; Zadkov, V.N. [International Laser Center, Moscow State University, 119899 Moscow (Russia)

1996-05-01

216

Alkaloid-fullerene systems through photocycloaddition reactions.  

PubMed

The photocycloaddition of tertiary amines to ¿60fullerene (C(60)) is an interesting and useful reaction. We wished to extend the applications of this type of reaction through an investigation of the photoaddition of alkaloids to C(60) for the purpose of synthesizing novel and complex photoadducts that are difficult to obtain by usual methods. Irradiation of tazettine (2) or gramine (3) with C(60) in toluene leads to formation of one monoadduct (6 or 7), whereas scandine (1a) or 10-hydroxyscandine (1b) reacts with C(60) photochemically to give two products, the expected ¿6,6 monoadduct (5a, 5b) and a new type of monoadduct with a bis-¿6, 6 closed structure (4a, 4b). These new structures were characterized by UV-vis, FT-IR, (1)H NMR, (13)C NMR, (1)H-(1)H COSY, ROESY, HMQC (heteronuclear multiple-quantum coherence), and HMBC (heteronuclear multiple-bond connectivity) spectroscopy. The techniques of time-of-flight secondary ion MS (TOF-SIMS) and field desorption MS (FD-MS) were used for the mass determination. (3)He NMR analysis of the product mixture from photoaddition of 1a to C(60) containing a (3)He atom ((3)He@C(60)) led to two peaks at -9.091 and -11.090 ppm relative to gaseous (3)He, consistent with formation of a ¿6, 6-closed monoadduct and a bis-¿6,6 closed adduct. Presumably, the bis-¿6, 6 closed adducts are formed by an intramolecular ¿2 + 2 cycloaddition of the vinyl group to the adjacent 6,6-ring junction of C(60) after the initial photocycloaddition. PMID:10864768

Guo, L W; Gao, X; Zhang, D W; Wu, S H; Wu, H M; Li, Y J; Wilson, S R; Richardson, C F; Schuster, D I

2000-06-16

217

Probing degradation in complex engineering silicones by 1H multiple quantum NMR  

SciTech Connect

Static {sup 1}H Multiple Quantum Nuclear Magnetic Resonance (MQ NMR) has recently been shown to provide detailed insight into the network structure of pristine silicon based polymer systems. The MQ NMR method characterizes the residual dipolar couplings of the silicon chains that depend on the average molecular weight between physical or chemical constraints. Recently, we have employed MQ NMR methods to characterize the changes in network structure in a series of complex silicone materials subject to numerous degradation mechanisms, including thermal, radiative, and desiccative. For thermal degradation, MQ NMR shows that a combination of crosslinking due to post-curing reactions as well as random chain scissioning reactions occurs. For radiative degradation, the primary mechanisms are via crosslinking both in the network and at the interface between the polymer and the inorganic filler. For samples stored in highly desiccating environments, MQ NMR shows that the average segmental dynamics are slowed due to increased interactions between the filler and the network polymer chains.

Maxwell, R S; Chinn, S C; Giuliani, J; Herberg, J L

2007-09-05

218

Models of far-IR sources at W3-IRS4 and W3-IRS5  

NASA Astrophysics Data System (ADS)

Far-IR continuum maps made with the KAO of W3 at 47 and 95 micrometers show peaks identified with the mid-IR sources IRS4 and IRS5 and extended emission identified with the radio source W3A. We have taken the steepest radial scan profiles from the peaks at IRS4 and IRS5 to represent the objects as spherical clouds. Spherically symmetric models were created in an attempt to match the observed profiles. Radiative transfer dust cloud models heated by central protostars or stars do not match extended emission in the 47 micrometers scan profile for any assumed density distribution for either source. However, both sources can be approximately fit by power law density profiles and ad hoc temperature profiles which are much less steep than those by the single source radiative transfer models. One possible physical explanation for the shallow temperature gradients suggested by the data is heating by a distribution of luminosity sources.

Campbell, M. F.; Campbell, M. B.; Butner, H. M.; Lester, Dan F.; Harvey, Paul M.; Evans, N. J., II

219

Dynamics of chitosan by (1)h NMR relaxation.  

PubMed

The dynamics of chitosan (CS) in solution have been studied by (1)H NMR relaxation [longitudinal (T(1)) and transverse (T(2)) relaxation times and NOE] as a function of the degrees of acetylation (DA, 1-70) and polymerization (DP, 10-1200), temperature (278-343 K), concentration (0.1-30 g/L), and ionic strength (50-400 mM). This analysis points to CS as a semirigid polymer with increased flexibility at higher DA in agreement with reduced electrostatic repulsions between protonated amino groups. PMID:20593894

Novoa-Carballal, Ramon; Fernandez-Megia, Eduardo; Riguera, Ricardo

2010-08-01

220

Absolute configuration and 1H NMR characterization of rosmaridiphenol diacetate.  

PubMed

The correction of patented structure 1 of rosmaridiphenol, an antioxidant isolated from rosemary, Rosmarinus officinalis, was made recently. The correct structure is proposed as 11,12-dihydroxy-8,11,13-icetexatrien-1-one (2a) based on 2D NMR data. In order to further support the structure, this work reports the single-crystal X-ray analysis, the complete (1)H NMR assignment by full spin-spin simulation, and the absolute configuration of the diacetate 2b derived via vibrational circular dicroism measurements in comparison with density functional theory calculated data. PMID:22424272

Muñoz, Marcelo A; Perez-Hernandez, Nury; Pertino, Mariano W; Schmeda-Hirschmann, Guillermo; Joseph-Nathan, Pedro

2012-03-16

221

Synthesis, spectroscopic studies and crystal structure of ( E)-2-(2,4-dihydroxybenzylidene)thiosemicarbazone and ( E)-2-[(1 H-indol-3-yl)methylene]thiosemicarbazone  

Microsoft Academic Search

Thiosemicarbazone Schiff bases (1 and 2) derived from 2,4-dihydroxybenzaldehyde, indoline-3-carbaldehyde and thiosemicarbazone have been synthesized and their structures were elucidated by elemental analysis, FT-IR, 1H NMR, 13C NMR and UV–visible spectroscopic techniques. The structures of compounds 1 and 2 have also been examined cyrstallographically. The title compounds 1 and 2 crystallize in the monoclinic space group C2\\/c and triclinic space

Mustafa Yildiz; Hüseyin Ünver; Digdem Erdener; Askin Kiraz; Nazan Ocak ?skeleli

2009-01-01

222

NGC 7538 IRS 1 - Subarcsecond resolution recombination line and (N-15)H3 maser observations  

SciTech Connect

The present imaging of the NGC 7538 IRS 1-associated (N-15)H3 (J, K) = (3, 3) maser emission with 0.2-arcsec resolution shows the strongest such masers, which may be amplifying the strong double-lobe radio continuum core of the IRS 1 H II region, to be concentrated in two regions separated by about 0.2 arcsec. Observations of several hydrogen recombination line transitions indicate that the velocity of the IRS H II region is similar to that of the ambient molecular cloud. 23 refs.

Gaume, R.A.; Johnston, K.J.; Nguyen, H.A.; Wilson, T.L.; Dickel, H.R. (US Navy, Center for Advanced Space Sensing, Washington, DC (United States) Max-Planck-Inst. fuer Radioastronomie, Bonn (West Germany) Illinois Univ., Urbana (United States))

1991-08-01

223

The IR Theory Discussion List  

NSDL National Science Digital Library

The Theory of International Relations List is a moderated, manually distributed list for the scholarly discussion of ideas and issues directly related to International Relations (IR) theory and its research, as well as communicating with others involved or interested in IR theory and its research.

1996-01-01

224

23Na and (1)H NMR microimaging of intact plants.  

PubMed

(23)Na NMR microimaging is described to map, for the first time, the sodium distribution in living plants. As an example, the response of 6-day-old seedlings of Ricinus communis to exposure to sodium chloride concentrations from 5 to 300 mM was observed in vivo using (23)Na as well as (1)H NMR microimaging. Experiments were performed at 11.75 T with a double resonant (23)Na-(1)H probehead. The probehead was homebuilt and equipped with a climate chamber. T(1) and T(2) of (23)Na were measured in the cross section of the hypocotyl. Within 85 min (23)Na images with an in-plane resolution of 156 x 156 micrometer were acquired. With this spatial information, the different types of tissue in the hypocotyl can be discerned. The measurement time appears to be short compared to the time scale of sodium uptake and accumulation in the plant so that the kinetics of salt stress can be followed. In conclusion, (23)Na NMR microimaging promises great potential for physiological studies of the consequences of salt stress on the macroscopic level and thus may become a unique tool for characterizing plants with respect to salt tolerance and salt sensitivity. PMID:10828197

Olt, S; Krötz, E; Komor, E; Rokitta, M; Haase, A

2000-06-01

225

Profiling formulated monoclonal antibodies by (1)h NMR spectroscopy.  

PubMed

Nuclear magnetic resonance (NMR) is arguably the most direct methodology for characterizing the higher-order structure of proteins in solution. Structural characterization of proteins by NMR typically utilizes heteronuclear experiments. However, for formulated monoclonal antibody (mAb) therapeutics, the use of these approaches is not currently tenable due to the requirements of isotope labeling, the large size of the proteins, and the restraints imposed by various formulations. Here, we present a new strategy to characterize formulated mAbs using (1)H NMR. This method, based on the pulsed field gradient stimulated echo (PGSTE) experiment, facilitates the use of (1)H NMR to generate highly resolved spectra of intact mAbs in their formulation buffers. This method of data acquisition, along with postacquisition signal processing, allows the generation of structural and hydrodynamic profiles of antibodies. We demonstrate how variation of the PGSTE pulse sequence parameters allows proton relaxation rates and relative diffusion coefficients to be obtained in a simple fashion. This new methodology can be used as a robust way to compare and characterize mAb therapeutics. PMID:24006877

Poppe, Leszek; Jordan, John B; Lawson, Ken; Jerums, Matthew; Apostol, Izydor; Schnier, Paul D

2013-09-24

226

One-Pot Synthesis of 3,4-Dihydropyrimidine-2-(1H)-ones Using CsF–Celite as Catalyst  

Microsoft Academic Search

A facile, efficient, and environmentally benign procedure for the synthesis of 3,4-dihydropyrimidin-2-(1H)-ones via the cyclocondensation reaction of aromatic aldehyde, ethyl acetoaceate, and urea catalyzed by CsF–Celite was developed. This environmentally friendly method is superior to previous methods with respect to reaction time, yield, and workup.

Sirirat Chancharunee; Pilaiwan Pinhom; Manat Pohmakotr; Patrick Perlmutter

2009-01-01

227

3,4,5-Trihydr-oxy-N'-(1H-indol-2-ylmethyl-idene)benzohydrazide-1H-indole-2-carbaldehyde azine-methanol (2/1/2).  

PubMed

The title compound, 2C(16)H(13)N(3)O(4)·C(18)H(14)N(4)·2CH(4)O, was crystallized from the reaction between 3,4,5-trihydroxy-benzoyl-hydrazine and indole-2-carbaldehyde in a mixture of ethanol and methanol. The compound is a stoichiometric 2:1 cocrystal of the methanol-solvated reaction product, 3,4,5-trihydr-oxy-N'-(1H-indol-2-ylmethyl-idene)benzohydrazide and 1H-indole-2-carbaldehyde azine that arose unexpectedly during the synthesis. The former mol-ecules are linked by O-H?O hydrogen bonds and also by ?-? stacking inter-actions between benzoyl-hydrazide rings into a two-dimensional network. The methanol solvent mol-ecules are hydrogen bonded to this network. The centrosymmetric azine mol-ecules are not engaged in hydrogen bonding. PMID:21579996

Khaledi, Hamid; Alhadi, Abeer A; Mohd Ali, Hapipah; Robinson, Ward T; Abdulla, Mahmood A

2009-12-12

228

Molecular structure of 2-chloromethyl-1H-benzimidazole hydrochloride: Single crystal, spectral, biological studies, and DFT calculations  

NASA Astrophysics Data System (ADS)

In the present work, structural studies on 2-chloromethyl-1H-benzimidazole hydrochloride have been performed extensively by X-ray crystallography, 1H NMR, FT-IR, UV/vis, and elemental analysis. The title compound crystallizes in a monoclinic space group P21/c with a = 7.1982 (3) Å, b = 9.4513 (5) Å, c = 14.0485 (7) Å and ? = 102.440 (3)° forming an infinite chain structure parallel to " b" axis through the intermolecular hydrogen bond. Optimized geometrical structure, harmonic vibrational frequencies, natural bonding orbital (NBO) and frontier molecular orbitals (FMO) were obtained by DFT/B3LYP method combined with 6-31G(d) basis set. TD-DFT calculations help to assign the electronic transitions. The 1H NMR chemical shifts were computed at the B3LYP/6-311 + G(2d,p) level of theory in different solvents by applying GIAO method using the polarizable continuum model (PCM). The title compound was screened for its antibacterial activity referring to Tetracycline as a standard antibacterial agent.

Abdel Ghani, Nour T.; Mansour, Ahmed M.

2012-02-01

229

Molecular structure of 2-chloromethyl-1H-benzimidazole hydrochloride: single crystal, spectral, biological studies, and DFT calculations.  

PubMed

In the present work, structural studies on 2-chloromethyl-1H-benzimidazole hydrochloride have been performed extensively by X-ray crystallography, (1)H NMR, FT-IR, UV/vis, and elemental analysis. The title compound crystallizes in a monoclinic space group P2(1)/c with a=7.1982 (3) Å, b=9.4513 (5) Å, c=14.0485 (7) Å and ?=102.440 (3)° forming an infinite chain structure parallel to "b" axis through the intermolecular hydrogen bond. Optimized geometrical structure, harmonic vibrational frequencies, natural bonding orbital (NBO) and frontier molecular orbitals (FMO) were obtained by DFT/B3LYP method combined with 6-31G(d) basis set. TD-DFT calculations help to assign the electronic transitions. The (1)H NMR chemical shifts were computed at the B3LYP/6-311+G(2d,p) level of theory in different solvents by applying GIAO method using the polarizable continuum model (PCM). The title compound was screened for its antibacterial activity referring to Tetracycline as a standard antibacterial agent. PMID:22153740

Abdel Ghani, Nour T; Mansour, Ahmed M

2011-11-18

230

Structural Characterization and Antimicrobial Activity of 2-(5-H\\/methyl-1 H -benzimidazol-2-yl)-4-bromo\\/nitrophenol Ligands and their Fe(NO 3 ) 3 Complexes  

Microsoft Academic Search

2-(5-H\\/methyl-1H-benzimidazol-2-yl)-4-bromo\\/nitro-phenol (HLx:X=1–4) ligands and their iron(III) nitrate complexes have been synthesized and characterized. In all of the complexes, the\\u000a ligands are bidentate, via one imine nitrogen atom and a phenolate oxygen atom. The coordination is completed with a bidentate nitrate anion, and a\\u000a water molecule. Elemental analysis, molar conductivity, magnetic susceptibility, FT-Raman, FT-IR (mid i.r., far i.r.), UV–visible\\u000a and as

Aydin Tavman; Naz M. Agh-Atabay; Abdollah Neshat; Fahrettin Gucin; Basaran Dulger; Durata Haciu

2006-01-01

231

Palladium(II) thiocarboxamide complexes: synthesis, characterisation and application to catalytic Suzuki coupling reactions.  

PubMed

A simple route to synthesise palladium(II) complexes from the reaction of N-substituted pyridine-2-thiocarboxamide ligands and PdCl(2)(PPh(3))(2) has been developed. The new complexes are very soluble in common solvents and have been fully characterised (elemental analysis, FT-IR, (1)H, (31)P, (13)C-NMR), including an X-ray diffraction analysis. The molecular structures of all the complexes were determined and reveal the presence of square planar geometry around Pd with little distortion. The complexes were tested in the Suzuki coupling of electronically deactivated aryl and heteroaryl bromides and were found to have much greater activity, without using any promoting additives or phase transfer agent under aerobic conditions. Higher reaction rates are obtained by varying R substituents on the aromatic ring of pyridine-2-thiocarboxamide. The effect of other variables on the cross-coupling reaction, such as temperature, solvent and base, is also reported. PMID:22399145

Sindhuja, Elangovan; Ramesh, Rengan; Liu, Yu

2012-03-08

232

Transition Probabilities for 1H in Strong Magnetic Fields  

NASA Astrophysics Data System (ADS)

Atomic data alike transition probabilities (TPs) and oscillator strengths for 1H in strong magnetic fields are necessery for modelling the atmospheres of magnetized white dwarf or neutron stars. We worked out a mathematical treatment, which allowes us to compute any bound--bound dipole TPs. In our method we obtain the values of these quadratic functionals directly. We derive initial value problems fore some first order ordinary differential equations, which solutions provide the required values to us. Proceeding this way, we avoid the computation of eigenfuntions and awkward numerical integration of their compositions. Stability of computations may be proven. So, as opposed to the traditional way the TPs can be obtained in the same accuracy as the eigenvalues. The computation of the latter is described in Balla and Benko (1996), J. Phys. A 29, 6747.

Benko, J. M.; Balla, K.

233

The Dibenzalacetone Reaction Revisited  

NASA Astrophysics Data System (ADS)

A modification of a classic experiment is described that incorporates a discovery approach to organic synthesis. Groups of students are assigned target molecules of the dibenzalketone type and are given a sample procedure for the parent dibenzalacetone reaction. They are asked to design a synthesis of their target based on the model reaction and to modify the model reaction so it will work for their synthesis. They show they have synthesized the target with 1H NMR.

Hull, Leslie A.

2001-02-01

234

Hexamethyldisiloxane-based nanoprobes for (1) H MRI oximetry.  

PubMed

Quantitative in vivo oximetry has been reported using (19) F MRI in conjunction with reporter molecules, such as perfluorocarbons, for tissue oxygenation (pO(2) ). Recently, hexamethyldisiloxane (HMDSO) has been proposed as a promising alternative reporter molecule for (1) H MRI-based measurement of pO(2) . To aid biocompatibility for potential systemic administration, we prepared various nanoemulsion formulations using a wide range of HMDSO volume fractions and HMDSO to surfactant ratios. Calibration curves (R(1) versus pO(2) ) for all emulsion formulations were found to be linear and similar to neat HMDSO for low surfactant concentrations (<10% v/v). A small temperature dependence in the calibration curves was observed, similar to previous reports on neat HMDSO, and was characterized to be approximately 1?Torr/?°C under hypoxic conditions. To demonstrate application in vivo, 100 µL of this nanoemulsion was administered to healthy rat thigh muscle (Fisher 344, n=6). Dynamic changes in mean thigh tissue pO(2) were measured using the PISTOL (proton imaging of siloxanes to map tissue oxygenation levels) technique in response to oxygen challenge. Changing the inhaled gas to oxygen for 30 min increased the mean pO(2) significantly (p<0.001) from 39?±?7 to 275?±?27?Torr. When the breathing gas was switched back to air, the tissue pO(2) decreased to a mean value of 45?±?6?Torr, not significantly different from baseline (p>0.05), in 25?min. A first-order exponential fit to this part of the pO(2) data (i.e. after oxygen challenge) yielded an oxygen consumption-related kinetic parameter k=0.21?±?0.04?min(-1) . These results demonstrate the feasibility of using HMDSO nanoemulsions as nanoprobes of pO(2) and their utility to assess oxygen dynamics in vivo, further developing quantitative (1) H MRI oximetry. PMID:21412864

Gulaka, Praveen K; Rastogi, Ujjawal; McKay, Madalyn A; Wang, Xianghui; Mason, Ralph P; Kodibagkar, Vikram D

2011-03-15

235

Liver Metabolite Concentrations Measured with 1H MR Spectroscopy  

PubMed Central

Purpose: To determine the feasibility of measuring choline and glycogen concentrations in normal human liver in vivo with proton (hydrogen 1 [1H]) magnetic resonance (MR) spectroscopy. Materials and Methods: Signed consent to participate in an institutional review board–approved and HIPAA-compliant study was obtained from 46 subjects (mean age, 46 years ± 17 [standard deviation]; 24 women) consecutively recruited during 285 days. Navigator-gated MR images were used to select 8-mL volumes for point-resolved spectroscopy (PRESS) with a 35-msec echo time. Line widths were minimized with fast breath-hold B0 field mapping and further manual shimming. Navigator-gated spectra were recorded with and without water suppression to determine metabolite concentrations with water signals as an internal reference. In three subjects, echo time was varied to determine the glycogen and choline T2. Linear regression analysis was used to examine relations between choline, hepatic lipid content, body mass index, glycogen content, and age. Results: Choline concentrations could be determined in 46 of 48 studies and was found to be 8.6 mmol per kilogram of wet weight ± 3.1 (range, 3.8–17.6; n = 44). Twenty-seven spectra in 25 individuals with narrow line widths and low lipid content were adequate for quantitation of glycogen. The glycogen (glucosyl unit) concentration was 38.1 mmol/kg wet weight ± 14.4. The T2 of combined glycogen peaks in the liver of three subjects was 36 msec ± 8. Choline levels showed a weak but significant correlation with glycogen (r2 = 0.15; P < .05) but not with lipid content. Conclusion: Navigator-gated and gradient-echo shimmed PRESS 1H MR spectroscopy may allow quantification of liver metabolites that are important for understanding and identifying disorders of glucose and lipid metabolism. © RSNA, 2012 Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12112344/-/DC1

Pettigrew, Roderic I.; Gharib, Ahmed M.

2012-01-01

236

Kinetics of reactions occurring during polyurethane synthesis  

NASA Astrophysics Data System (ADS)

We have used Fourier transform IR spectroscopy to study the kinetics of reaction between phenylisocyanate and oligomeric polyols at room temperature. We have determined the degree of conversion and the reaction rate constants for urethane formation.

Volkova, E. R.; Tereshatov, V. V.; Karmanov, V. I.

2010-11-01

237

Facile and efficient synthesis of acridinediones from primary amino alcohols via three-component condensation reactions assisted by microwave irradiation  

Microsoft Academic Search

Microwave irradiation of three component reaction of dimedone, appropriate aromatic aldehydes and amino alcohols in a stoichiometrical ratio 2:1:1 for few minutes afforded the formation of a stable fused three membered ring of the corresponding 3,6,6-tetramethyl-2,3,4,5,6,7,8,9,10-decahydroacridine-1,8-dione derivatives in an excellent yield (80–91%). The structure of all products has been characterized by X-ray crystal structural analyses, 13C NMR, 1H NMR, IR

Antar A. Abdelhamid; S. K. Mohamed; A. M. Maharramov; A. N. Khalilov; M. A. Allahverdiev

238

Comparison of Ir oxide film redox kinetics in sulfuric and p-toluene sulfonic acid solutions  

Microsoft Academic Search

Ir oxide films were grown and studied electrochemically in 0.4 M H2SO4 and in 0.3 M para-toluenesulfonic acid (TsOH). The equilibrium CV characteristics for films formed in these two solutions were very similar, even though the kinetics of the Ir(+III)\\/Ir(+IV) charge transfer reaction were ca. 10 times more rapid for films grown and studied in H2SO4 versus TsOH. From the

C Bock; V. I Birss

2001-01-01

239

2,2-Bis(hy-droxy-meth-yl)-2,3-dihydro-1H-pyrrolizin-1-one  

PubMed Central

The title compound, C9H11NO3, was prepared by an Aldol reaction of 2,3-dihydro-1H-pyrrolizin-1-one with formaldehyde. The asymmetric unit contains six mol­ecules. The pyrrolizine ring system in each mol­ecule is planar, the maximum atomic deviation being 0.066?(2)?Å. In the crystal structure, mol­ecules are liked together by an extensive O—H?O hydrogen-bonding network.

Ali, Yousuf; Peng, Yu; Hua, Erbing; Afza, Nighat; Khan, Rashid Ali

2010-01-01

240

Kinetic study of the oxidative addition reaction between methyl iodide and [Rh(FcCOCHCOCF 3)(CO)(PPh 3)]: Structure of [Rh(FcCOCHCOCF 3)(CO)(PPh 3)(CH 3)(I)  

Microsoft Academic Search

The kinetics of oxidative addition of CH3I to [Rh(FcCOCHCOCF3)(CO)(PPh3)], where Fc=ferrocenyl and (FcCOCHCOCF3)?=fctfa=ferrocenoylacetonato, have been studied utilizing UV\\/Vis, IR, 1H and 31P NMR techniques. Three definite sets of reactions involving isomers of at least two distinctly different classes of RhIII-alkyl and two different classes of RhIII-acyl species were observed. Rate constants for this reaction in CHCl3 at 25°C, applicable to

Jeanet Conradie; Gert J. Lamprecht; Andreas Roodt; Jannie C. Swarts

2007-01-01

241

Review of IR Letter Responses  

Center for Biologics Evaluation and Research (CBER)

... flow rates and ---(b)(4)---- were maintained. The firm's response appears acceptable. IR letter comment 2g(A): Please adjust your linear flow rate ... More results from www.fda.gov/biologicsbloodvaccines/vaccines/approvedproducts

242

Effect of Exercise on the Creatine Resonances in ^1H MR Spectra of Human Skeletal Muscle  

NASA Astrophysics Data System (ADS)

^1H MR spectra of human muscles were recorded before, during, and after fatiguing exercise. In contrast to expectations, it was found that the spectral contributions of creatinesolarphosphocreatine (CrsolarPCr) were subject to change as a function of exercise. In particular, the dipolar-coupled methylene protons of CrsolarPCr were found to be reduced in intensity in proportion to the co-registered PCr levels. Recovery after exercise and behavior under ischemic conditions provide further evidence to suggest that the contributions of the CH_2 protons of CrsolarPCr to ^1H MR spectra of human muscle in vivo reflect PCr rather than Cr levels. Variation of experimental parameters showed that this effect is not due to a trivial change in relaxation times. At present it can only be speculated about why the Cr resonances have reduced NMR visibility. If temporary binding to macromolecules should be involved, the free Cr concentration-important for equilibrium calculations of the creatine kinase reaction-might be different from what was previously assumed.

Kreis, R.; Jung, B.; Slotboom, J.; Felblinger, J.; Boesch, C.

1999-04-01

243

Phenylacetylene One-Dimensional Nanostructures on the Si(100)-2 1:H Surface  

SciTech Connect

Using ultrahigh vacuum (UHV) scanning tunneling microscopy (STM), many olefins have been shown to self-assemble on the hydrogen-passivated Si(100)-2 1 surface into one-dimensional nanostructures. This paper demonstrates that similar one-dimensional nanostructures can also be realized using alkynes. In particular, UHV STM, sum frequency generation (SFG), and density functional theory (DFT) are employed to study the growth mechanism and binding configuration of phenylacetylene (PA) one-dimensional nanostructures on the Si(100)-2 1:H surface. Molecular-resolution UHV STM images reveal the binding position and spacing of PA with respect to the underlying silicon dimer rows. Furthermore, UHV STM characterization of heteromolecular one-dimensional nanostructures of styrene and PA shows distinct electronic contrast between the two molecules, which is confirmed using simulated STM images derived from DFT and provides insight into the nature of PA binding to silicon. Additional evidence from SFG measurements corroborates the conclusion that the terminal carbon atoms of PA retain -conjugation following reaction to the Si(100)-2 1:H surface.

Walsh, Michael A. [Northwestern University, Evanston; Walter, Stephanie R. [Northwestern University, Evanston; Bevan, Kirk H [ORNL; Geiger, Franz M [ORNL; Hersam, Mark C [ORNL

2010-01-01

244

Nd(III) and Dy(III) coordination compounds based on 1H-tetrazolate-5-acetic acid ligands: Synthesis, crystal structures and catalytic properties  

SciTech Connect

Reactions of 1H-tetrazolate-5-acetic acid(H{sub 2}tza) with Nd(NO{sub 3}){sub 3}{center_dot}6H{sub 2}O or Dy(NO{sub 3}){sub 3}{center_dot}6H{sub 2}O with the presence of KOH under solvothermal conditions, produced two new coordination compounds, [M{sub 2}(tza){sub 3}(H{sub 2}O){sub 6}]{center_dot}2H{sub 2}O [M=Nd(1), Dy(2)]. Both compounds were structurally characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. Compounds 1 and 2 reveal 1D structures via bridging tza as linker. Furthermore, the compounds 1 and 2 showed a specific and good catalytic behavior for the polymerization of styrene, and the polymerization showed controlled characteristics. - Graphical Abstract: Two new coordination compounds, [M{sub 2}(tza){sub 3}(H{sub 2}O){sub 6}]{center_dot}2H{sub 2}O [M=Nd(1), Dy(2)] have been synthesis. 1 and 2 reveal 1D structures via bridging tza as linker, and showed a specific and good catalytic behavior for the polymerization of styrene. Highlights: Black-Right-Pointing-Pointer we have reported two novel compounds formed by H{sub 2}tza and Nd(III) or Dy(III). Black-Right-Pointing-Pointer Compounds 1 and 2 were found to have catalysis property for the photo-polymerization of styrene. Black-Right-Pointing-Pointer The high molecular weight polymers with narrow molecular weight distributions were obtained.

Li Qiaoyun; Chen Dianyu; He Minghua [Jiangsu Laboratory of Advanced Functional Materials, Department of Chemistry and Materials Engineering, Changshu Institute of Technology, Changshu 215500, Jiangsu (China); Yang Gaowen, E-mail: ygwsx@126.com [Jiangsu Laboratory of Advanced Functional Materials, Department of Chemistry and Materials Engineering, Changshu Institute of Technology, Changshu 215500, Jiangsu (China); Shen Lei; Zhai Chun; Shen Wei; Gu Kun; Zhao Jingjing [Jiangsu Laboratory of Advanced Functional Materials, Department of Chemistry and Materials Engineering, Changshu Institute of Technology, Changshu 215500, Jiangsu (China)

2012-06-15

245

CCD and IR array controllers  

NASA Astrophysics Data System (ADS)

A family of controllers has bene developed that is powerful and flexible enough to operate a wide range of CCD and IR focal plane arrays in a variety of ground-based applications. These include fast readout of small CCD and IR arrays for adaptive optics applications, slow readout of large CCD and IR mosaics, and single CCD and IR array operation at low background/low noise regimes as well as high background/high speed regimes. The CCD and IR controllers have a common digital core based on user- programmable digital signal processors that are used to generate the array clocking and signal processing signals customized for each application. A fiber optic link passes image data and commands to VME or PCI interface boards resident in a host computer to the controller. CCD signal processing is done with a dual slope integrator operating at speeds of up to one Megapixel per second per channel. Signal processing of IR arrays is done either with a dual channel video processor or a four channel video processor that has built-in image memory and a coadder to 32-bit precision for operating high background arrays. Recent developments underway include the implementation of a fast fiber optic data link operating at a speed of 12.5 Megapixels per second for fast image transfer from the controller to the host computer, and supporting image acquisition software and device drivers for the PCI interface board for the Sun Solaris, Linux and Windows 2000 operating systems.

Leach, Robert W.; Low, Frank J.

2000-08-01

246

Probing a CMP-Kdn synthetase by 1H, 31P, and STD NMR spectroscopy.  

PubMed

CMP-Kdn synthetase catalyses the reaction of sialic acids (Sia) and cytidine-5'-triphosphate (CTP) to the corresponding activated sugar nucleotide CMP-Sia and pyrophosphate PP(i). STD NMR experiments of a recombinant nucleotide cytidine-5'-monophosphate-3-deoxy-d-glycero-d-galacto-nonulosonic acid synthetase (CMP-Kdn synthetase) were performed to map the binding epitope of the substrate CTP and the product CMP-Neu5Ac. The STD NMR analysis clearly shows that the anomeric proton of the ribose moiety of both investigated compounds is in close proximity to the protein surface and is likely to play a key role in the binding process. The relative rates of the enzyme reaction, derived from (1)H NMR signal integrals, show that Kdn is activated at a rate 2.5 and 3.1 faster than Neu5Ac and Neu5Gc, respectively. Furthermore, proton-decoupled (31)P NMR spectroscopy was successfully used to follow the enzyme reaction and clearly confirmed the appearance of CMP-Sia and the inorganic pyrophosphate by-product. PMID:15629150

Haselhorst, Thomas; Münster-Kühnel, Anja K; Stolz, Anita; Oschlies, Melanie; Tiralongo, Joe; Kitajima, Ken; Gerardy-Schahn, Rita; von Itzstein, Mark

2005-02-11

247

Theoretical study about the 5-azido-1H-tetrazole and its ion salts.  

PubMed

Periodic DFT method has been firstly used to calculate the bulk structure, electronic structure, electrical transferring and thermodynamic properties of crystalline 5-azido-1H-tetrazole (HCN?) and its four different salts. The anion CN?(-) was included in all of the salts such as ammonium 5-azidotetrazolate ([NH?](+)[CN?](-)), hydrazinium 5-azidotetrazolate ([N?H?](+)[CN?](-)), guanidinium 5-azidotetrazolate ([CH?N?](+)[CN?](-)?·?H?O) and 1-aminoguanidinium 5- azidotetrazolate ([CH?N?](+)[CN?](-)). The simulation is in reasonable agreement with the experimental results. It is found the salts of HCN? are more stable than itself because the band gap of the salts is larger. The density of state shows the p states of them (including HCN? and its four salts) have played a very significant role in the reaction. PMID:23412760

Wang, Kun; Zhang, Jianguo; Shang, Jing; Zhang, Tonglai

2013-02-15

248

Hydrate layers on ice particles and superheated ice: a {sup 1}H NMR microimaging study  

SciTech Connect

Recent observations on the interaction of methane gas with ice surfaces have led to the suggestion that the resulting hydrate layer prevents the encapsulated ice from melting at its usual temperature. This would require ice to exist in a superheated state. The authors have examined the product of the gas-solid reaction with {sup 1}H NMR imaging. The imaging experiments show that the hydrate-encapsulated ice is able to melt at its usual melting point. As a possible alternative model, the authors suggest that a considerable amount of ice inside the hydrate layer can be converted to hydrate and liquid water under isothermal and constant volume conditions, the hydrate layer acting as an insulating, semipermeable layer that insulates processes inside the hydrate layer from external bulk temperature and pressure measurements.

Moudrakovski, I.L.; Ratcliffe, C.I.; McLaurin, G.E.; Simard, B.; Ripmeester, J.A. [National Research Council of Canada, Ottawa, Ontario (Canada). Steacie Inst. for Molecular Sciences

1999-07-01

249

Car Exhaust Catalysis from First Principles:  Selective NO Reduction under Excess O 2 Conditions on Ir  

Microsoft Academic Search

Combining energetic data from density functional theory with thermodynamic calculations, we have studied in detail selective NO reduction under excess O2 conditions on Ir. We show that excess O2 can readily poison the Ir catalyst for NO reduction and the poisoning starts from a low O coverage on the surface. The adsorbed O switches the reaction selectivity from reduction (N2

Zhi-Pan Liu; Stephen J. Jenkins; David A. King

2004-01-01

250

3-hydroxy-2(1H)-pyridinone chelating agents  

DOEpatents

Disclosed is a series of improved metal chelating agents, which are highly effective upon both injection and oral administration; several of the most effective are of low toxicity. These chelating agents incorporate within their structure 1-hydroxy-2-pyridinone (1,2-HOPO) and 3-hydroxy-2-pyridinone (3,2-HOPO) moieties with a substituted carbamoyl group ortho to the hydroxy or oxo groups of the hydroxypyridinone ring. The electron-withdrawing carbamoyl group increases the acidity of the hydroxypyridinones. In the metal complexes of the chelating agents, the amide protons form very strong hydrogen bonds with its adjacent HOPO oxygen donor, making these complexes very stable at physiological conditions. The terminal N-substituents provides a certain degree of lipophilicity to the 3,2-HOPO, increasing oral activity. Also disclosed is a method of making the chelating agents and a method of producing a known compound, 3-hydroxy-1-alkyl-2(1H)pyridinone, used as a precursor to the chelating agent, safely and in large quantities. 2 figs.

Raymond, K.N.; Xu, J.

1997-04-29

251

1H Detected 13C Echo Planar Imaging  

NASA Astrophysics Data System (ADS)

Cyclic J cross polarisation (CYCLCROP) is a sensitive method for the noninvasive monitoring of 13C distributions and fluxes. The PRAWN rotating frame Hartmann-Hahn mixing sequence ameliorates problems associated with sensitivity to Hartmann-Hahn mismatch and reduces RF power deposition. The combination of CYCLCROP with echo planar imaging (EPI) for spatial encoding of the proton detected carbon signal allows efficient use of the available signal to be made, permitting a significant improvement in the temporal resolution of any study. We report here on some initial experiments to demonstrate the feasibility of echo planar proton detected 13C imaging using CYCLCROP based upon the PRAWN module, including the application of the technique to the measurement of transport and accumulation of 13C-labelled sucrose in a castor bean seedling. Two methods that can be used to eliminate the effect of the J-splitting in the EP images are presented. In addition, a fast, image-based B1 field-mapping method which may be used to quantitatively map the low frequency RF field in a dual resonant (13C/1H) probe is presented. The technique utilises the above described imaging method, permitting fully quantitative, 64×64 axial field maps to be generated in about a minute. .

Hudson, Alex. M. J.; Köckenberger, Walter; Heidenreich, Michael; Chandrakumar, Narayanan; Kimmich, Rainer; Bowtell, Richard

2002-03-01

252

3-hydroxy-2(1H)-pyridinone chelating agents  

DOEpatents

Disclosed is a series of improved metal chelating agents, which are highly effective upon both injection and oral administration; several of the most effective are of low toxicity. These chelating agents incorporate within their structure 1-hydroxy-2-pyridinone (1,2-HOPO) and 3-hydroxy-2-pyridinone (3,2-HOPO) moieties with a substituted carbamoyl group ortho to the hydroxy or oxo groups of the hydroxypyridinone ring. The electron-withdrawing carbamoyl group increases the acidity of the hydroxypyridinones. In the metal complexes of said chelating agents, the amide protons form very strong hydrogen bonds with its adjacent HOPO oxygen donor, making these complexes very stable at physiological conditions. The terminal N-substituents provides a certain degree of lipophilicity to said 3,2-HOPO, increasing oral activity. Also disclosed is a method of making the chelating agents and a method of producing a known compound, 3-hydroxy-1-alkyl-2(1H)pyridinone, used as a precursor to the chelating agent, safely and in large quantities.

Raymond, Kenneth N. (Berkeley, CA); Xu, Jide (Berkeley, CA)

1997-01-01

253

On the Jovian Near-IR Auroral H2 Emission  

NASA Astrophysics Data System (ADS)

Jupiter's auroral cascade causes H2 emission in the near-IR quadrupole lines, in addition to the FUV emission. Unlike the FUV aurora, the near-IR aurora can be observed from ground-based observatories; and has in fact been observed as emission in the H2 (1-0) band in the spectra of Jupiter and Uranus (NASA SP-494, 229, 1989; ApJ 524, 1059, 1999). Unlike the near-IR H3+ aurora, which is formed by the reaction of H2 ionized by the cascade reacting with neutral H2, the H2 aurora can emit from atmospheric levels below the homopause, where H3+ would be destroyed by chemical reaction with hydrocarbons. H2 thus probes the auroral energy input at deeper levels. We present ground-based observations of Jupiter's auroral H2 emission from the (1-0) Q-branch taken from McDonald Observatory using the CoolSpec Cassegrain IR spectrometer at the 2.7m telescope. We discuss the rotational temperature and excited H2 column in the auroral arc for various extracted System III longitudes and compare the results to previous FUV H2 and near-IR H3+ observations of Jupiter and Uranus. Significant overpopulation of the v=1 vibrational level is found, compared to thermal equilibrium, due to the auroral cascade.

Trafton, L. M.; Lester, D. F.

2001-11-01

254

Synthesis, crystal structure, HF and DFT calculations of 1-(2-chlorobenzyl)-N-(1-(2-chlorobenzyl)-4,5-dihydro-1H-imidazol-2-yl)-1H-benzimidazol-2-amine  

NASA Astrophysics Data System (ADS)

The titled compound ( 1), has been synthesized and characterized by IR and 1H-NMR spectroscopy, and single crystal X-ray diffraction. The compound crystallizes in the triclinic space group P-1. The crystal structure is stabilized by C-H…? and aromatic ?-? interactions. There are also intramolecular N-H…N and C-H…N hydrogen bonds in the molecule. The use of quantum chemical calculations to characterise and optimise the choice of material is illustrated by ab initio treatments. Vibrational frequencies and LUMO-HOMO energy difference of 1 have also been investigated by Density functional theory (DFT) and Hartree-Fock (HF) calculations. Calculated frequencies are in good agreement with the corresponding experimental data.

Yüksektepe, Çi?dem; Çali?kan, Nezihe; Genç, Murat; Servi, Süleyman

2010-12-01

255

1H NMR studies of aerosol-OT reverse micelles with alkali and magnesium counterions: preparation and analysis of MAOTs.  

PubMed

Simple procedures and characterization of a series of well-defined precursors are described for preparation of a unique microenvironment in nanoreactors, reverse micelles. The Na(+), K(+), Rb(+), Cs(+), and Mg(2+) surfactants were prepared using liquid-liquid ion exchange using chloride and nitrate salts. The surfactants were characterized using (1)H NMR spectroscopy and a variety of other techniques. (1)H NMR spectroscopy was found to be a sensitive probe for characterization of the size of the nanoreactor as well as its water content. (1)H NMR spectra can be used for detailed characterization of reactions in confined environments when counterion effects are likely to be important. (1)H NMR spectroscopy revealed two separate peaks corresponding to water in Mg(AOT)2 samples; one peak arises from water coordinated to the Mg(2+) ion while the other peak arises from bulk water. The two water signals arise directly from the slow exchange of the water coordinated to Mg(2+) in these microemulsions with water in the water pool, and provide an opportunity to study hydration of Mg(2+). This work thus extends the potential use of MAOT microemulsions for applications such as in green chemistry. PMID:18484757

Stahla, Michelle L; Baruah, Bharat; James, Dustin M; Johnson, Michael D; Levinger, Nancy E; Crans, Debbie C

2008-05-17

256

Possible assignment of chiral twin bands in {sup 188}Ir  

SciTech Connect

High-spin states in the doubly-odd Z=77 nucleus {sup 188}Ir were populated in the {sup 186}W({sup 7}Li,5n) reaction at 52 MeV. Two nearly degenerate {delta}I=1 sequences with the same parity were established. Both bands have been assigned the {pi}h{sub 9/2}x{nu}i{sub 13/2} configuration, based on the systematic behavior of these excitations in the Ir nuclei and on the measured values for the B(M1)/B(E2) ratios, and they are suggested as candidates for a chiral doublet.

Balabanski, D.L.; Danchev, M. [Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996 (United States); Faculty of Physics, St. Kliment Ohridski University of Sofia, BG-1164 Sofia (Bulgaria); Hartley, D.J.; Zeidan, O.; Zhang Jingye [Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996 (United States); Riedinger, L.L. [Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996 (United States); Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Barton, C.J.; Beausang, C.W.; Caprio, M.A.; Casten, R.F.; Cooper, J.R.; Hecht, A.A.; Kruecken, R.; Novak, J.R.; Zyromski, K.E. [WNSL, Physics Department, Yale University, New Haven, Connecticut 06520 (United States); Zamfir, N.V. [WNSL, Physics Department, Yale University, New Haven, Connecticut 06520 (United States); Clark University, Worcester, Massachusetts 10610 (United States); National Institute for Physics and Nuclear Engineering, Bucharest-Magurele (Romania)

2004-10-01

257

Radiation induced degradation of EPR by IR oxidation profiling  

NASA Astrophysics Data System (ADS)

Infrared absorption spectroscopy has been used to investigate the effect of ?-radiation on ethylene-propylene copolymer loaded with different amount of antioxidant. The oxidation profiles were obtained analyzing slices of the samples by an IR microscope. The IR spectra have shown that the antioxidant content does not affect the shape of the oxidation profiles; their dependence on thickness and dose rate is in good agreement with the Clough and Gillen model. Our results indicate that the antioxidant does not affect the reactions involved in the oxidation process and the oxygen distribution on the sample.

Baccaro, S.; Buontempo, U.; D'Atanasio, P.

1993-07-01

258

Synthesis and herbicidal activity of N,N-diethyl-3-(arylselenonyl)-1H-1,2,4-triazole-1-carboxamide.  

PubMed

Based on the carbamoyl triazole herbicide Cafenstrole, 12 novel selenium-containing compounds were designed and synthesized. All of the compounds were characterized and confirmed by IR, 1H NMR, and high-resolution mass spectroscopy. The bioassay tests showed that some of the compounds (C2, C4, C(7-8), and C12) exhibited good inhibitory activity against cucumber (Cucumis sativus L.) and semen euphorbiae (Leptochloa chinensis N.). Especially, compound C6 inhibited the growth of cucumber and semen euphorbiae by >90% at a concentration of 1.875 microg/mL, and the inhibition of the compound on the rice (Oryza sativa L.) was only 8.3% at a concentration of 7.5 microg/mL, which indicated a higher selectivity between weed and rice than that shown by Cafenstrole. PMID:17002445

Ma, Yanming; Liu, Runhui; Gong, Xiuying; Li, Zhong; Huang, Qingchun; Wang, Haishui; Song, Gonghua

2006-10-01

259

1-Carboxymethyl-3-methyl-1H-imidazol-3-ium chloride 2-(3-methyl-1H-imidazol-3-ium-1-yl)acetate monohydrate: a crystal stabilized by imidazolium zwitterions.  

PubMed

The title compound, C6H9N2O2(+)·Cl(-)·C6H8N2O2·H2O, contains one 2-(3-methyl-1H-imidazol-3-ium-1-yl)acetate inner salt molecule, one 1-carboxymethyl-3-methyl-1H-imidazol-3-ium cation, one chloride ion and one water molecule. In the extended structure, chloride anions and water molecules are linked via O-H...Cl hydrogen bonds, forming an infinite one-dimensional chain. The chloride anions are also linked by two weak C-H...Cl interactions to neighbouring methylene groups and imidazole rings. Two imidazolium moieties form a homoconjugated cation through a strong and asymmetric O-H...O hydrogen bond of 2.472?(2)?Å. The IR spectrum shows a continuous D-type absorption in the region below 1300?cm(-1) and is different to that of 1-carboxymethyl-3-methylimidazolium chloride [Xuan, Wang & Xue (2012). Spectrochim. Acta Part A, 96, 436-443]. PMID:24096510

Zhang, Heng; Chang, Liangliang; Wang, Na; Xuan, Xiaopeng

2013-09-06

260

Regional neonatal brain absolute thermometry by (1) H MRS.  

PubMed

Therapeutic hypothermia is standard care for infants with moderate to severe encephalopathy. (1) H MRS thermometry (MRSt) measures regional brain absolute temperature using the temperature-dependent water chemical shift. This study evaluates the clinical feasibility of MRSt in human neonates, and correlates white matter (WM) and thalamus (Thal) MRSt with conventional rectal temperature (T(rectal) ) measurement. Fifty-six infants born at term underwent perinatal MRSt for suspected hypoxic-ischaemic brain injury and 33 infants born preterm had MRSt at a term-equivalent age; 56 of the 89 had T(rectal) measured after MRSt of either a Thal or posterior WM voxel, or both. MRSt used point-resolved spectroscopy (no water suppression; TR?=?1370?ms; TE?=?288?ms; 1.5?×?1.5?×?1.5?cm(3) Thal and 1.1?×?1.3?×?1.4?cm(3) WM voxels). Time domain data were phase and frequency corrected before summation and motion-corrupted data were excluded from further analysis using simple criteria [preprocessing?+?quality assurance (QA)]. Two published water temperature-dependence calibrations [both using cerebral creatine (Cr), choline (Cho) and N-acetylaspartate (Naa) as independent reference peaks] were compared. The temperature measurements derived from Cr, Cho and Naa were combined to give a single amplitude-weighted combination temperature (T(AWC) ). WM and Thal T(AWC) correlated linearly with T(rectal) (Thal slope, 0.82?±?0.04, R(2) ?=?0.85, p?

Bainbridge, Alan; Kendall, Giles S; Vita, Enrico De; Hagmann, Cornelia; Kapetanakis, Andrew; Cady, Ernest B; Robertson, Nicola J

2012-10-16

261

Recall of Level 1 H-31B Air Detector/Clamping Devices, Level ...  

Center for Biologics Evaluation and Research (CBER)

... has received complaints for the Level 1 H-31B Air Detector/Clamping Device and Level 1 H-1200 Fast Flow Fluid ... Food and Drug Administration. ... More results from www.fda.gov/biologicsbloodvaccines/safetyavailability/recalls

262

New IR detectors pig-tailed with IR fibers  

NASA Astrophysics Data System (ADS)

New generation of Mercury-Cadmium-Telluride (MCT) high performance infrared radiation (IR) detectors with IR-fiber input has been developed and fabricated. This new product is originated from 25 years experience in MCT detectors and IR fiber optics technologies. Range of products includes single- and multi-element detectors designed for registration of optical signals in spectral range from 2 to 18 ?m. Detectors design is integrated or modular and includes package, sensitive element, cooling system, operating temperature sensor, optical components such as narrow band-pass filter and/or lens and/or different kind of optical window, optical connection unit and fiber pig-tail or fiber cable. Cooling system options include thermoelectric cooler, long-holding time dewar filled with liquid nitrogen, Joule-Thomson micro-liquidizer and Stirling-cycle cooler. Registered infrared radiation is delivered to sensitive area of detector through either Polycrystalline InfraRed (PIR-) Fiber (4 - 18 ?m) or Chalcogenide IR-glass (CIR-) Fiber (2 - 6 ?m). Unique feature intrinsic to Hg1-xCdxTe (MCT) alloys to form continuous series of alloy compositions "x" with proportionally changed energy gap Eg(x,T) allows to tune spectral responsivity of detector sensitive element with ordered spectral range and hence to use every time the highest sensitive detector.

Artiouchenko, Viatcheslav G.; Chekanova, Galina V.; Lartsev, Ivan Y.; Lobachev, Vladimir A.; Nikitine, Mikhail S.

2003-09-01

263

A simultaneous (15)N, (1)H- and (13)C, (1)H-HSQC with sensitivity enhancement and a heteronuclear gradient echo.  

PubMed

New pulse sequences are introduced and discussed that allow for simultaneous acquisition of (15)N,(1)H-and (13)C,(1)H-HSQC correlations for fully (13)C,(15)N-labeled biomacromolecules in combination with hetero-nuclear gradient echoes and sensitivity enhancement. The pulse sequence experimentally found to be optimal can be used as a building block, especially in time-consuming multidimensional NMR experiments. Due to the excellent solvent suppression obtained by employing heteronuclear gradient echoes, which allows detection of resonances under the water resonance, it would be possible to record two sensitivity-enhanced 4D experiments simultaneously on one sample dissolved in H(2)O, e.g. a 4D (13)C,(1)H-HSQC-NOESY-(15)N, (1)H/(13)C,(1)H-HSQC. PMID:22911437

Sattler, M; Maurer, M; Schleucher, J; Griesinger, C

1995-01-01

264

Dose parameters of 125I and 192Ir seed sources.  

PubMed

As mandated by an NCI brachytherapy contract, we measured dosimetric parameters for 192Ir seeds and two models of 125I seeds. Measurements were with LiF powder in a water-equivalent phantom. Data were corrected for background, sample mass, and finite detector volume. Selected parameters were also investigated through Monte Carlo calculations. Results are presented in terms of a dose parametrization that is described in detail, and are compared to published data. Our results agreed well with published data for relative quantities such as radial and angular dose dependence. Our measured value for the 192Ir dose factor was 4.55 cGy(H2O) cm2 mCi-1 h-1, also in good agreement with commonly used values. However, the measured dose factors for 125I seed models 6702 and 6711 were 1.18 and 1.06 cGy(H2O) cm2 mCi-1 h-1, values well below those in general use. PMID:2770636

Weaver, K A; Smith, V; Huang, D; Barnett, C; Schell, M C; Ling, C

265

40 CFR 721.10587 - 1H-Pyrazole, 3,4-dimethyl-.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false 1H-Pyrazole, 3,4-dimethyl-. 721.10587...Chemical Substances § 721.10587 1H-Pyrazole, 3,4-dimethyl-. (a) Chemical...chemical substance identified as 1H-pyrazole, 3,4-dimethyl- (PMN...

2013-07-01

266

1 H-Indole-3 acetonitrile glycosides from Capparis spinosa fruits  

Microsoft Academic Search

Two new glucose-containing 1H-indole-3-acetonitrile compounds, capparilosides A and B, were isolated from mature fruits of Capparis spinosa. On the basis of spectral and chemical evidence, they were shown to be 1H-indole-3-acetonitrile 4-O-?-glucopyranoside and 1H-indole-3-acetonitrile 4-O-?- (6?-O-?-glucopyranosyl)-glucopyranoside, respectively.

?hsan Çali?; Ay?e Kuruüzüm; Peter Rüedi

1999-01-01

267

Preparation of a Rapidly Forming Poly(ferrocenylsilane)-Poly(ethylene glycol)-based Hydrogel by a Thiol-Michael Addition Click Reaction.  

PubMed

The synthesis of a rapidly forming redox responsive poly(ferrocenylsilane)-poly(ethylene glycol) (PFS-PEG)-based hydrogel is described, achieved by a thiol-Michael addition click reaction. PFS bearing acrylate side groups (PFS-acryl) was synthesized by side group modification of poly(ferrocenyl(3-iodopropyl)methylsilane) (PFS-I) and characterized by (1) H NMR, (13) C NMR, and FT-IR spectroscopy. The equilibrium swelling ratio, morphology, rheology, and redox responsive properties of the PFS-PEG-based hydrogel are reported. PMID:21567631

Sui, Xiaofeng; van Ingen, Lennard; Hempenius, Mark A; Vancso, G Julius

2010-10-19

268

Surface oxides of Ir(111) prepared by gas-phase oxygen atoms  

NASA Astrophysics Data System (ADS)

The Ir(111) surface is oxidized with gas-phase oxygen atoms under vacuum condition to achieve an oxidation level beyond its saturation coverage for chemisorption. Two surface oxides, rutile IrO2 of (100) domain and corundum Ir2O3 of (001) domain, have been grown at 550 K with different oxygen exposure of 3.6 × 105 L and 7.2 × 105 L respectively. The temperature programmed desorption (TPD) experiment of rutile IrO2(100) shows its desorption curve (at 4 K s- 1) peaks at 750 K, followed by a long tail of less pronounced desorption features. On the other hand, TPD of corundum Ir2O3(001) displays a symmetric trace, peaking at 880 K. Carbon monoxide titration experiments show that adsorbed CO reduces corundum Ir2O3(001) at 400 K, but CO does not adsorb on rutile IrO2(100) and no reduction reaction occurs. Evidently, among the two surface oxides, corundum Ir2O3(001) involves in catalysis of carbon monoxide oxidation, while rutile IrO2(100) does not. The formation of two surface oxides is also compared, we conclude that the atom arrangement favors Ir2O3(001) at the oxide/metal interface.

Chung, Wen-Hung; Tsai, Dah-Shyang; Fan, Liang-Jen; Yang, Yaw-Wen; Huang, Ying-Sheng

2012-12-01

269

A one-pot reaction to synthesize two types of fluorescent materials containing benzothiazolyl moiety.  

PubMed

Two different types of fluorescent materials containing benzothiazolyl moiety, 2-(benzothiazol-2-yl)phenol derivatives and 3-(benzothiazol-2-yl)coumarin derivatives, were synthesized synchronously using ethyl cyanoacetate, appropriate aromatic aldehyde and 2-aminothiophenol as the starting materials under the catalysis of benzoic acid by one-pot reaction. This method has the advantages of mild reaction conditions, easy processing and low waste. All synthesized compounds were characterized by elemental analysis, IR, (1)H NMR spectra. The structures of 2-(benzothiazol-2-yl)phenol derivatives, 2-(benzothiazol-2-yl)phenol (BTP) and 2-(benzothiazol-2-yl)naphthol (BTN), were determined by X-ray single crystal analysis. The UV-vis absorption and photoluminescence spectra of all synthesized compounds were investigated. The 2-(benzothiazol-2-yl)phenol derivatives exhibit bright green emissions and 3-(benzothiazol-2-yl)coumarin derivatives emit bright blue light in solutions. PMID:23501939

Yu, Tianzhi; Zhang, Chengcheng; Zhao, Yuling; Chai, Haifang; Fan, Duowang; Ma, Ying; Yao, Shanglei; Li, Wentao

2013-02-17

270

Structure and antioxidant activities of sulfated guar gum: homogeneous reaction using DMAP/DCC catalyst.  

PubMed

It was essential to understand the chemical structure of polysaccharides for further research and biochemical or medical application of this natural biopolymer. In the present study, sulfated derivatives of guar gum with high degree of sulfation (DS) were synthesized using 4-dimethylaminopyridine (DMAP)/dimethylcyclohexylcarbodiimide (DCC) as catalyst in homogeneous conditions. The effects of the ratio of chlorosulfuric acid to pyridine, the content of catalyst and reaction temperature were investigated. Results of FT-IR, (1)H and (13)C NMR indicated that C-6 substitution was predominant in sulfated polysaccharide. In the sulfation reaction, a sharp decrease in M(W) was observed. The enhanced antioxidant activities of sulfated polysaccharides were not a function of a single factor but a combination of high DS and low molecule weight. PMID:22484325

Wang, Junlong; Zhao, Baotang; Wang, Xiaofang; Yao, Jian; Zhang, Ji

2012-03-29

271

A one-pot reaction to synthesize two types of fluorescent materials containing benzothiazolyl moiety  

NASA Astrophysics Data System (ADS)

Two different types of fluorescent materials containing benzothiazolyl moiety, 2-(benzothiazol-2-yl)phenol derivatives and 3-(benzothiazol-2-yl)coumarin derivatives, were synthesized synchronously using ethyl cyanoacetate, appropriate aromatic aldehyde and 2-aminothiophenol as the starting materials under the catalysis of benzoic acid by one-pot reaction. This method has the advantages of mild reaction conditions, easy processing and low waste. All synthesized compounds were characterized by elemental analysis, IR, 1H NMR spectra. The structures of 2-(benzothiazol-2-yl)phenol derivatives, 2-(benzothiazol-2-yl)phenol (BTP) and 2-(benzothiazol-2-yl)naphthol (BTN), were determined by X-ray single crystal analysis. The UV-vis absorption and photoluminescence spectra of all synthesized compounds were investigated. The 2-(benzothiazol-2-yl)phenol derivatives exhibit bright green emissions and 3-(benzothiazol-2-yl)coumarin derivatives emit bright blue light in solutions.

Yu, Tianzhi; Zhang, Chengcheng; Zhao, Yuling; Chai, Haifang; Fan, Duowang; Ma, Ying; Yao, Shanglei; Li, Wentao

2013-05-01

272

A suggestion for the IRS  

Microsoft Academic Search

Suggests that private psychology practitioners, hospitals, and psychological centers should be allowed to deduct discounts given to clients who are unable to pay or who are unable to pay the full fee. Currently, the Internal Revenue Service (IRS) does not permit such deductions. (0 ref)

William P. Hill

1971-01-01

273

IrYdium Project, The  

NSDL National Science Digital Library

The IrYdium Project, and CREATE Project, develop educational software that can be integrated flexibly into introductory chemistry courses nationwide. Our goal is to create simulation-based learning environments where college and high school students can approach chemistry more like practicing scientists and see interesting real-world applications of key concepts.

274

MARYLAND COASTAL BAYS IR 2002  

EPA Science Inventory

The Maryland Coastal Bays Program Implementation Review (IR) summarizes the progress and challenges ahead for the Program through examination of its activities in relation to the CCMP. During the CCMP planning phase the stakeholders prioritized the actions and determined the impl...

275

Atmospheric Entry Experiments at IRS  

Microsoft Academic Search

Entering the atmosphere of celestial bodies, spacecrafts encounter gases at velocities of several km\\/s, thereby being subjected to great heat loads. The thermal protection systems and the environment (plasma) have to be investigated by means of computational and ground facility based simulations. For more than a decade, plasma wind tunnels at IRS have been used for the investigation of TPS

M. Auweter-Kurtz; P. Endlich; G. Herdrich; H. Kurtz; T. Laux; S. Löhle; N. Nazina; S. Pidan

2002-01-01

276

Monitoring bound HA1(H1N1) and HA1(H5N1) on freely suspended graphene over plasmonic platforms with infrared spectroscopy  

NASA Astrophysics Data System (ADS)

Infrared (IR) spectroscopy provides fingerprinting of the energy and orientation of molecular bonds. The IR signals are generally weak and require amplification. Here we present a new plasmonic platform, made of freely suspended graphene, which was coating periodic metal structures. Only monolayer thick films were needed for a fast signal recording. We demonstrated unique IR absorption signals of bound proteins: these were the hemagglutinin area (HA1) of swine influenza (H1N1) and the avian influenza (H5N1) viruses bound to their respective tri-saccharides ligand receptors. The simplicity and sensitivity of such approach may find applications in fast monitoring of binding events.

Banerjee, Amrita; Chakraborty, Sumit; Altan-Bonnet, Nihal; Grebel, Haim

2013-09-01

277

Experimental design of Fenton and photo-Fenton reactions for the treatment of ampicillin solutions.  

PubMed

This paper discusses the degradation of the antibiotic ampicillin (AMP) by Fenton and photo-Fenton reactions. The influence of the three main variables that govern the degradation kinetic (pH, H(2)O(2) and Fe(II) concentrations) was evaluated with a circumscribed central composite (CCC) model and a response surface methodology (RSM). The optimal conditions for Fenton and photo-Fenton reactions are very similar: pH 3.5, around 400 micromol L(-1) H(2)O(2) and 87 micromol L(-1) Fe(II). Under such optimized conditions, the complete AMP removal was reached after 10 min and 3 min for Fenton and photo-Fenton reactions, respectively. A very similar removal profile in the first 2 min of reaction was observed for both systems with a high degree of degradation (close to 90%). After a 2-min treatment, the Fenton reaction became slower, and the IR product analysis suggests the formation of different oxidation intermediates. This observation was confirmed by the COD and TOC evolution during the reactions. The oxidation degree, measured as Average Oxidation State (AOS), indicates that the photo-Fenton reaction produces faster most of the oxidation intermediates. The antibacterial activity (AA) of the oxidized samples was determined using the inhibition halo methodology on agar plates cultured with Staphylococcus aureus bacteria. The course of AA is concomitant with the AMP removal, which indicates that the long-term intermediates do not present antibiotic properties. PMID:20097473

Rozas, Oscar; Contreras, David; Mondaca, M Angélica; Pérez-Moya, Montserrat; Mansilla, Héctor D

2010-01-13

278

Electrochemical studies of Pt\\/Ir–IrO 2 electrocatalyst as a bifunctional oxygen electrode  

Microsoft Academic Search

In the present study, Ir nanoparticles are deposited on the surface of IrO2 nanoparticles with microwave-assisted polyol process. Then the obtained Ir–IrO2 nanocomposite is used as a support to prepare Pt\\/Ir–IrO2 nanocomposite, which has been demonstrated as an excellent bifunctional oxygen catalyst for unitized regenerative fuel cell. X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), and transmission electron microscopy (TEM) characterizations

Fan-Dong Kong; Sheng Zhang; Ge-Ping Yin; Zhen-Bo Wang; Chun-Yu Du; Guang-Yu Chen; Na Zhang

279

Anharmonic vibrations of N-H in Cl(-)(N-methylacetamide)1(H2O)0-2Ar2 cluster ions. Combined IRPD experiments and BOMD simulations.  

PubMed

Infrared Predissociation (IRPD) spectra of Cl(-)(NMA)1(H2O)0-2Ar2 combined with Born-Oppenheimer Molecular Dynamics (BOMD) IR spectra have been acquired, providing the structure and dynamics of these systems. We show that the chloride ion is bound to the hydrogen of the amide N-H group, forming a strong ionic hydrogen bond, weakening the N-H stretch, and shifting it to lower frequency. The presence of water molecules enhances the ionic hydrogen bond by binding to the amide carbonyl oxygen of NMA and shifts the N-H stretch further to lower frequency. The BOMD IR spectra can recapture all, but about 100 cm(-1), of the 600 to 700 cm(-1) shifts due to the strong N-H stretch anharmonicities observed in experiments. This residual error was found to be due to the lack of zero point energy in the classical treatment of motion in the BOMD method. PMID:23986352

Beck, Jordan P; Gaigeot, Marie-Pierre; Lisy, James M

2013-08-29

280

Cobalt, nickel, copper and zinc complexes with 1,3-diphenyl-1H-pyrazole-4-carboxaldehyde Schiff bases: antimicrobial, spectroscopic, thermal and fluorescence studies.  

PubMed

Two new Schiff bases of 1,3-diphenyl-1H-pyrazole-4-carboxaldehyde and 4-amino-5-mercapto-3-methyl/H-1,2,4-triazole [HL(1-2)] and their Cobalt, Nickel, Copper and Zinc complexes have been synthesized and characterized by elemental analyses, spectral (UV-vis, IR, (1)H NMR, Fluorescence) studies, thermal techniques and magnetic measurements. A square planar geometry for Cu(II) and octahedral geometry for Co(II), Ni(II) and Zn(II) complexes have been proposed. In order to evaluate the biological activity of Schiff bases and to assess the role of metal ion on biological activity, the pyrazole Schiff bases and their metal complexes have been studied in vitro antibacterial against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa and antifungal against Aspergillus niger, and Aspergillus flavus. In most of the cases higher activity was exhibited upon coordination with metal ions. PMID:22429912

Singh, Kiran; Kumar, Yogender; Puri, Parvesh; Kumar, Mahender; Sharma, Chetan

2012-03-03

281

Metallothionein 1 h tumour suppressor activity in prostate cancer is mediated by euchromatin methyltransferase 1.  

PubMed

Metallothioneins (MTs) are a group of metal binding proteins thought to play a role in the detoxification of heavy metals. Here we showed by microarray and validation analyses that MT1h, a member of MT, is down-regulated in many human malignancies. Low expression of MT1h was associated with poor clinical outcomes in both prostate and liver cancer. We found that the promoter region of MT1h was hypermethylated in cancer and that demethylation of the MT1h promoter reversed the suppression of MT1h expression. Forced expression of MT1h induced cell growth arrest, suppressed colony formation, retarded migration, and reduced invasion. SCID mice with tumour xenografts with inducible MT1h expression had lower tumour volumes as well as fewer metastases and deaths than uninduced controls. MT1h was found to interact with euchromatin histone methyltransferase 1 (EHMT1) and enhanced its methyltransferase activity on histone 3. Knocking down of EHMT1 or a mutation in MT1h that abrogates its interaction with EHMT1 abrogated MT1h tumour suppressor activity. This demonstrates tumour suppressor activity in a heavy metal binding protein that is dependent on activation of histone methylation. PMID:23355073

Han, Yu-Chen; Zheng, Zhong-Liang; Zuo, Ze-Hua; Yu, Yan P; Chen, Rui; Tseng, George C; Nelson, Joel B; Luo, Jian-Hua

2013-06-01

282

Pseudospin doublet aligned structure in doubly odd 186Ir  

NASA Astrophysics Data System (ADS)

186Ir has been restudied through the 180Hf(11B,5n) reaction at 65 MeV using in-beam ?-ray and conversion-electron spectroscopy. The unfavored component of the doubly decoupled band was established and shown to be consistent with a description in terms of the ?h9/2??[411~1/2,3/2] structure, i.e., the coupling of an aligned proton and a neutron pseudospin doublet.

Cardona, M. A.; Debray, M. E.; García Bermúdez, G.; Hojman, D.; Kreiner, A. J.; Somacal, H.; Burlon, A.; Davidson, J.; Davidson, M.; Levinton, G.; Ozafrán, M.; Vázquez, M.; Napoli, D. R.; Rico, J.; Bazzacco, D.; Burch, R.; de Acuña, D.; Lenzi, S. M.; Medina, N.; Rossi Alvarez, C.; Blasi, N.; Lo Bianco, G.; de Boer, J.; Frischke, D.; Maier, H. J.

1997-01-01

283

Selective hydrogenation and H-D exchange of unsaturated hydrocarbons on Pd(100)-p(1x1)-H(D)  

SciTech Connect

The adsorption and reactions of unsaturated hydrocarbons (ethylene, propene, 1-butene, acetylene, allene, 1,3-butadiene, 1,3,5-hexatriene, and 1,5-hexadiene) have been investigated on the Pd(100)-p(1x1)-H and Pd(100)-p(1x1)-D surfaces using temperature-programmed reaction spectroscopy (TPRS). It is found that 1-alkenes (ethylene, propene, and 1-butene) undergo efficient H-D exchange reactions below 300 K for all C-H bonds, whereas no hydrogenation products (alkanes) are observed. Conjugated polyenes (acetylene, allene, 1,3-butadiene, and 1,3,5,-hexatriene) undergo selective hydrogenation to corresponding alkenes below or around 300 K, whereas no exchange reaction is observed to occur for the parent molecules. Nonconjugated polyene (1,5-hexadiene) undergoes both exchange and hydrogenation reactions, with its reactivity in between 1-alkenes and conjugated polyenes. The exchange reaction is proposed to occur via reversible hydrogenation to a half-hydrogenated intermediate. The relative quantities and evolution temperatures of successively H-D exchanged products are reproduced by kinetic simulations of competition between desorption and reaction. The absence of alkene hydrogenation may be due to stronger metal-hydrogen bonds on Pd(100) than on other metals such as Pt and Rh. Strong bonding of the half-hydrogenated intermediate to the surface may be the reason for the irreversible hydrogenation of conjugated polyenes to alkenes. Both exchange and hydrogenation reactions occur at all coverages, but at low coverages the reaction products dehydrogenate to C(a) and H(a) without product evolution. 23 refs., 8 figs., 2 tab.

Guo, Xing-Cai; Madix, R.J. [Stanford Univ., CA (United States)

1995-09-01

284

Synthesis and evaluation of novel 1-(1 H-1,2,4-triazol-1-yl)-2-(2,4-difluorophenyl)-3-[(4-substitutedphenyl)-piperazin-1-yl]-propan-2-ols as antifungal agents  

Microsoft Academic Search

A series of 1-(1H-1,2,4-triazol-1-yl)-2-(2,4-difluorophenyl)-3-[(4-substitutedphenyl)-piperazin-1-yl]-propan-2-ols have been designed and synthesized on the basis of the structure–activity relationships and antimycotic mechanism of azole antifungal agents. Their structures were confirmed by elemental analysis, IR, MS, 1H NMR and 13C NMR. Results of preliminary antifungal tests against six human pathogenic fungi (Candida albicans, Candida parapsilosis, Cryptococcus neoformans, Candida tropicalis, inherently fluconazole-resistant Candida krusei, Candida

Qing-Yan Sun; Wan-Nian Zhang; Jian-Ming Xu; Yong-Bing Cao; Qiu-Ye Wu; Da-Zhi Zhang; Chao-Mei Liu; Shi-Chong Yu; Yuan-Ying Jiang

2007-01-01

285

Synthesis and biological activity of Magnesium(II) complexes of heptaaza Schiff base macrocyclic ligands; 1 H and 13 C chemical shifts computed by the GIAO-DFT and CSGT-DFT methodologies  

Microsoft Academic Search

Two new pendant armed Schiff base macrocyclic complexes, [MgL1](ClO4)2 (1), and [MgL2](ClO4)2 (2), have been prepared via cyclocondensation of 2,6-diformylpyridine and 2,6-diacetylpyridine with two hexadentate hexaamines,\\u000a ten and tmen, in the presence of Mg(II) ion. The ligands are 15-membered pentaaza macrocycles having two 2-aminoethyl pendant\\u000a arms. The newly prepared complexes are investigated by IR, 1H NMR, 13C{1H} NMR, DEPT(135), COSY(H,

Hamid Khanmohammadi; Hassan Keypour; Mehdi Salehei Fard; Mohammad H. Abnosi

2009-01-01

286

1H NMR investigations of the molecular nature of cobalt(II) ions in human saliva.  

PubMed

High-resolution (1)H NMR spectroscopy demonstrated that addition of Co(II) ions to isolated human salivary supernatants (HSSs) gave rise to its complexation by a variety of biomolecules. The relative efficacies of these complexants/chelators in this context were classifiable by the influence of added Co(II) on their line-widths and chemical shift values, and also the added Co(II) concentration-dependence of these spectral modifications. Those which were most affected by the addition of this metal ion were lactate > formate ?histidinate > succinate, this order reflecting the ability of these complexants to compete for the available Co(II) in terms of (1) thermodynamic equilibrium constants for the formation of their complexes and (2) their HSS concentrations. Since many of these HSS Co(II) complexants (particularly lactate, formate and histidine) serve as powerful ()OH scavengers, the results acquired indicate that any of this radical generated from the Co(II) source in such complexes via pseudo-Fenton reactions may be 'site-specifically' scavenged. The significance of these observations regarding the in vivo corrosion of cobalt-containing metal alloy dental prostheses (e.g., Co-Cr alloys), the availability of trace levels of this metal ion in human saliva, and cobalt toxicity, is discussed. PMID:22342562

Chang, Hubert; Tomoda, Shigetaka; Silwood, Christopher J L; Lynch, Edward; Grootveld, Martin

2012-02-10

287

Borax: An Ecofriendly and Efficient Catalyst for One-Pot Synthesis of 3,4-Dihydropyrimidine-2(1H)-ones under Solvent-Free Conditions  

Microsoft Academic Search

Borax in the presence of a very small amount of 5 M sulfuric acid efficiently catalyses the three-component condensation of an aldehyde, ?-ketoester, and urea or thiourea to afford the corresponding 3,4-dihydropyrimidin-2(1H)-ones or 3,4-dihydropyrimidin-2(1H)-thiones in good to excellent yields under solvent-free conditions at 80 °C. Compared with the classical Biginelli reaction conditions, this new method has the advantage of excellent yield, short

Jayashree Nath; Mihir K. Chaudhuri

2010-01-01

288

The Use and Evaluation of Scaffolding, Student Centered-Learning, Behaviorism, and Constructivism to Teach Nuclear Magnetic Resonance and IR Spectroscopy in a Two-Semester Organic Chemistry Course  

ERIC Educational Resources Information Center

|Since 2002, infrared spectroscopy (IR) and nuclear magnetic resonance (NMR) spectrometry have been introduced at the beginning of the first-semester organic chemistry lab course at this university. Starting in 2008, each individual student was given 20 unique homework problems that consisted of multiple-choice [superscript 1]H NMR and IR problems…

Livengood, Kimberly; Lewallen, Denver W.; Leatherman, Jennifer; Maxwell, Janet L.

2012-01-01

289

Time-resolved IR chemiluminescence in gas-phase chemical kinetics  

Microsoft Academic Search

The time-resolved IR chemiluminescence method based on the study of the chemiluminescence of vibrationally excited molecules formed in chemical reactions is discussed. The approaches used in the study of elementary reactions and complex processes are systematised. The technique is compared with other methods for the study of gas-phase chemical kinetics. The bibliography includes 76 references.

Evgenii N. Chesnokov; Viktor N. Panfilov

1999-01-01

290

Preparation, spectroscopic properties of 1,4-di (N,N-diisopropylacetamido)-2,3(1H,4H)-quinoxalinedione (L) lanthanide complexes and the supramolecular structure of [Nd{sub 2}L{sub 2}(NO{sub 3}){sub 6}(H{sub 2}O){sub 2}].H{sub 2}O  

SciTech Connect

The reaction of lanthanide nitrate with 1,4-di (N,N-diisopropylacetamido)-2,3(1H,4H)-quinoxalinedione (L) yields six novel Ln(III) complexes ([Ln{sub 2}L{sub 2}(NO{sub 3}){sub 6}(H{sub 2}O){sub 2}].H{sub 2}O) which are characterized by elemental analysis, thermogravimetric analysis (TGA), conductivity measurements, IR, electronic and {sup 1}H NMR spectroscopies. A new quinoxalinedione-based ligand is used as antenna ligand to sensitize the emission of lanthanide cations. The lowest triplet state energy level of the ligand in the nitrate complex matches better to the resonance level of Eu(III) and Sm(III) than Tb(III) and Dy(III) ion. The f-f fluorescence is induced in the Eu{sup 3+} and Sm{sup 3+} complexes by exciting into the {pi}-{pi}* absorptions of the ligand in the UV. Furthermore, the crystal structures of a novel binuclear complex [Nd{sub 2}L{sub 2}(NO{sub 3}){sub 6}(H{sub 2}O){sub 2}].H{sub 2}O has been determined by single-crystal X-ray diffraction. The binuclear [Nd{sub 2}L{sub 2}(NO{sub 3}){sub 6}(H{sub 2}O){sub 2}].H{sub 2}O complex units are linked by the intermolecular hydrogen bonds and {pi}-{pi} interactions to form a two-dimensional (2-D) layer supramolecule. - Graphical abstract: Preparation, spectroscopic properties of 1,4-di (N,N-diisopropylacetamido)-2,3(1H,4H)-quinoxalinedione (L) lanthanide complexes and the supramolecular structure of [Nd{sub 2}L{sub 2}(NO{sub 3}){sub 6}(H{sub 2}O){sub 2}].H{sub 2}O.

Song Xueqin [College of Chemistry and Chemical Engineering, State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000 (China); School of Chemical and Biological Engineering, Lanzhou Jiaotong University, Lanzhou 730070 (China); Yu Yang [College of Chemistry and Chemical Engineering, State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000 (China); Liu Weisheng [College of Chemistry and Chemical Engineering, State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000 (China)], E-mail: liuws@lzu.edu.cn; Dou Wei; Zheng Jiangrong; Yao Junna [College of Chemistry and Chemical Engineering, State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000 (China)

2007-09-15

291

Molecular structure, heteronuclear resonance assisted hydrogen bond analysis, chemical reactivity and first hyperpolarizability of a novel ethyl-4-{[(2,4-dinitrophenyl)-hydrazono]-ethyl}-3,5-dimethyl-1H-pyrrole-2-carboxylate: a combined DFT and AIM approach.  

PubMed

A new ethyl-4-{[(2,4-dinitrophenyl)-hydrazono]-ethyl}-3,5-dimethyl-1H-pyrrole-2-carboxylate (EDPHEDPC) has been synthesized and characterized by FT-IR, (1)H NMR, UV-vis, DART-Mass spectroscopy and elemental analysis. Quantum chemical calculations have been performed by DFT level of theory using B3LYP functional and 6-31G(d,p) as basis set. The (1)H NMR chemical shifts are calculated using gauge including atomic orbitals (GIAO) approach in DMSO as solvent. The time dependent density functional theory (TD-DFT) is used to find the various electronic transitions and their nature within molecule. A combined theoretical and experimental wavenumber analysis confirms the existence of dimer. Topological parameters such as electron density (?(BCP)), Laplacian of electron density (nabla(2)?(BCP)), kinetic electron energy density (G(BCP)), potential electron density (V(BCP)) and the total electron energy density (H(BCP)) at bond critical points (BCP) have been analyzed by Bader's 'Atoms in molecules' AIM theory in detail. The intermolecular hydrogen bond energy of dimer is calculated as -12.51 kcal/mol using AIM calculations. AIM ellipticity analysis is carried out to confirm the presence of resonance assisted intra and intermolecular hydrogen bonds in dimer. The calculated thermodynamic parameters show that reaction is exothermic and non-spontaneous at room temperature. The local reactivity descriptors such as Fukui functions (f(k)(+), f(k)(-)), local softnesses (s(k)(-), s(k)(+)) and electrophilicity indices (?(k)(+), ?(k)(-)) analyses are performed to determine the reactive sites within molecule. Nonlinear optical (NLO) behavior of title compound is investigated by the computed value of first hyperpolarizability (?(0)). PMID:22446779

Singh, R N; Kumar, Amit; Tiwari, R K; Rawat, Poonam; Baboo, Vikas; Verma, Divya

2012-03-02

292

A combined experimental and theoretical (DFT and AIM) studies on synthesis, molecular structure, spectroscopic properties and multiple interactions analysis in a novel Ethyl-4-[2-(thiocarbamoyl)hydrazinylidene]-3,5-dimethyl-1H-pyrrole-2-carboxylate and its dimer  

NASA Astrophysics Data System (ADS)

In the present work, ethyl-4-[2-(thiocarbamoyl)hydrazinylidene]-3,5-dimethyl-1H-pyrrole-2-carboxylate (3) has been synthesized and characterized by 1H NMR, UV-Vis, FT-IR and Mass spectroscopy. The formation of the compound and its properties have also been evaluated by quantum chemical calculations using DFT, B3LYP functional and 6-31G(d,p) as basis set. The calculated thermodynamic parameters show that the formation of 3 is an exothermic and spontaneous reaction at room temperature. 1H NMR chemical shifts are calculated using gauge including atomic orbitals (GIAO) approach in DMSO-d6 as solvent. Time dependent density functional theory (TD-DFT) is used to calculate the energy (E), oscillator strength (f) and wavelength absorption maxima (?max) of various electronic transitions and their nature within the molecule. NBO analysis is carried out to investigate the charge transfer or charge delocalization in various intra- and intermolecular interactions of molecular system. The vibrational analysis indicates the formation of dimer in the solid state by intermolecular heteronuclear hydrogen bonding (Nsbnd H⋯O). Topological parameters at bond critical points (BCP) are calculated to analyze the strength and nature of various types of intra and intermolecular interactions in dimer by Bader's 'Atoms in molecules' AIM theory in detail. The binding energy of intermolecular multiple interactions is calculated to be 15.54 kcal/mol, using AIM calculation. The local reactivity descriptors such as Fukui functions (fk+,fk-), local softnesses (sk+,sk-) and electrophilicity indices (?k+,?k-) analyses are performed to determine the reactive sites within molecule.

Singh, R. N.; Kumar, Amit; Tiwari, R. K.; Rawat, Poonam

2013-08-01

293

Soybean biodiesel methyl esters, free glycerin and acid number quantification by 1H nuclear magnetic resonance spectroscopy.  

PubMed

Production of alternative fuels, such as biodiesel, from transesterification of vegetable oil driven by heterogeneous catalysts is a promising alternative to fossil diesel. However, achieving a successful substitution for a new renewable fuel depends on several quality parameters. (1)H NMR spectroscopy was used to determine the amount of methyl esters, free glycerin and acid number in the transesterification of soybean oil with methanol in the presence of hydrotalcite-type catalyst to produce biodiesel. Reaction parameters, such as temperature and time, were used to evaluate soybean oil methyl esters rate conversion. Temperatures of 100 to 180 °C and times of 20 to 240 min were tested on a 1 : 12 molar ratio soybean oil/methanol reaction. At 180 °C/240 min conditions, a rate of 94.5 wt% of methyl esters was obtained, where free glycerin and free fatty acids were not detected. PMID:23225640

Coral, Natasha; Rodrigues, Elizabeth; Rumjanek, Victor; Zamian, José Roberto; da Rocha Filho, Geraldo Narciso; da Costa, Carlos Emmerson Ferreira

2012-12-07

294

In-beam {gamma}-ray and {alpha}-decay spectroscopy of {sup 170}Ir  

SciTech Connect

Excited states in the highly neutron deficient odd-odd nucleus {sup 170}Ir have been investigated. The experiment was performed using the {sup 112}Sn({sup 60}Ni, pn){sup 170}Ir reaction and employing the recoil-decay tagging technique. Gamma rays were detected using the JUROGAM {gamma}-ray spectrometer and those belonging to {sup 170}Ir were selected based on recoil identification provided by the RITU gas-filled recoil separator and the GREAT spectrometer at the RITU focal plane. A partial level scheme of {sup 170}Ir is presented for the first time. New {alpha}-decay branches are assigned to {sup 170}Ir and a tentative level structure for {sup 166}Re is deduced from a study of the {alpha}-decay fine structure and the associated {alpha}-{gamma} correlations.

Hadinia, B.; Cederwall, B.; Wyss, R.; Johnson, A.; Lagergren, K.; Andgren, K.; Baeck, T.; Liotta, R. J.; Sandzelius, M. [Department of Physics, Royal Institute of Technology, SE-10691 Stockholm (Sweden); Joss, D. T.; Appelbe, D. E.; Barton, C. J.; Warner, D. D. [CCLRC, Daresbury Laboratory, Daresbury, Warrington, WA4 4AD (United Kingdom); Page, R. D.; Simpson, J.; Wiseman, D. R. [Oliver Lodge Laboratory, Department of Physics, University of Liverpool, Liverpool, L69 7ZE (United Kingdom); Scholey, C.; Eeckhaudt, S.; Grahn, T.; Greenlees, P. [Department of Physics, University of Jyvaeskylae, Post Office Box 35, University of Jyvaeskylae, FIN-40014 Jyvaeskylae (Finland)] (and others)

2007-10-15

295

Unusual behavior in the reactivity of 5-substituted-1H-tetrazoles in a resistively heated microreactor  

PubMed Central

Summary The decomposition of 5-benzhydryl-1H-tetrazole in an N-methyl-2-pyrrolidone/acetic acid/water mixture was investigated under a variety of high-temperature reaction conditions. Employing a sealed Pyrex glass vial and batch microwave conditions at 240 °C, the tetrazole is comparatively stable and complete decomposition to diphenylmethane requires more than 8 h. Similar kinetic data were obtained in conductively heated flow devices with either stainless steel or Hastelloy coils in the same temperature region. In contrast, in a flow instrument that utilizes direct electric resistance heating of the reactor coil, tetrazole decomposition was dramatically accelerated with rate constants increased by two orders of magnitude. When 5-benzhydryl-1H-tetrazole was exposed to 220 °C in this type of flow reactor, decomposition to diphenylmethane was complete within 10 min. The mechanism and kinetic parameters of tetrazole decomposition under a variety of reaction conditions were investigated. A number of possible explanations for these highly unusual rate accelerations are presented. In addition, general aspects of reactor degradation, corrosion and contamination effects of importance to continuous flow chemistry are discussed.

Gutmann, Bernhard; Glasnov, Toma N; Razzaq, Tahseen; Goessler, Walter; Roberge, Dominique M

2011-01-01

296

Unprecedented Construction of C?C Double Bonds via Ir-Catalyzed Dehydrogenative and Dehydrative Cross-Couplings.  

PubMed

Unprecedented constructions of C?C double bonds have been achieved by Ir-catalyzed intramolecular dehydrogenative and dehydrative cross-coupling of tertiary amines and ketones. The reactions are proposed to proceed via an Ir-mediated C-H activation mechanism. PMID:23621093

Nie, Shao-Zhen; Sun, Xiang; Wei, Wen-Tao; Zhang, Xue-Jing; Yan, Ming; Xiao, Jian-Liang

2013-04-26

297

Preliminary study of corrosion mechanisms of actinides alloys: calibration of FT-IR spectroscopy  

SciTech Connect

In situ analyzes of gaseous atmospheres could be performed by FT-IR spectroscopy in order to study the corrosion reactions of actinides. Nevertheless experimental conditions and the nature of studied species have a strong effect on IR absorption laws. Thus a prior calibration of our set-up is required to obtain an accurate estimation of gas concentration. For this purpose, the behavior of several air pure gases has been investigated according to their concentration from IR spectra. Reproducible results revealed subsequent increases of the most significant peak areas with gas pressure and small deviations from Beer Lambert's law. This preliminary work allowed to determine precise absorption laws for each studied pure gas in our in situ experimental conditions. Besides our FT-IR set-up was well suitable to quantitative analysis of gaseous atmosphere during corrosion reactions. Finally the effect of foreign gas will be investigated through more complex air mixtures to obtain a complete calibration network. (authors)

Magnien, Veronique; Cadignan, Marx; Faivret, Olivier; Rosa, Gaelle [Centre de Valduc, CEA, Is sur tille, 21120 (France)

2008-07-01

298

Ab initio calculation of 1H, 17O, 27Al and 29Si NMR parameters, vibrational frequencies and bonding energetics in hydrous silica and Na-aluminosilicate glasses  

NASA Astrophysics Data System (ADS)

Ab initio, molecular orbital (MO) calculations were performed on model systems of SiO 2, NaAlSi 3O 8 (albite), H 2O-SiO 2 and H 2O-NaAlSi 3O 8 glasses. Model nuclear magnetic resonance (NMR) isotropic chemical shifts (? iso) for 1H, 17O, 27Al and 29Si are consistent with experimental data for the SiO 2, NaAlSi 3O 8, H 2O-SiO 2 systems where structural interpretations of the NMR peak assignments are accepted. For H 2O-NaSi 3AlO 8 glass, controversy has surrounded the interpretation of NMR and infrared (IR) spectra. Calculated ? iso1H, ? iso17O, ? iso27Al and ? iso29Si are consistent with the interpretation of Kohn et al. (1992) that Si-(OH)-Al linkages are responsible for the observed peaks in hydrous Na-aluminosilicate glasses. In addition, a theoretical vibrational frequency associated with the Kohn et al. (1992) model agrees well with the observed shoulder near 900 cm -1 in the IR and Raman spectra of hydrous albite glasses. MO calculations suggest that breaking this Si-(OH)-Al linkage requires ˜+56 to +82 kJ/mol which is comparable to the activation energies for viscous flow in hydrous aluminosilicate melts.

Kubicki, J. D.; Sykes, D. G.

2004-10-01

299

Carbon nanotube IR detectors (SV)  

SciTech Connect

Sandia National Laboratories (Sandia) and Lockheed Martin Corporation (LMC) collaborated to (1) evaluate the potential of carbon nanotubes as channels in infrared (IR) photodetectors; (2) assemble and characterize carbon nanotube electronic devices and measure the photocurrent generated when exposed to infrared light;(3) compare the performance of the carbon nanotube devices with that of traditional devices; and (4) develop and numerically implement models of electronic transport and opto-electronic behavior of carbon nanotube infrared detectors. This work established a new paradigm for photodetectors.

Leonard, F. L.

2012-03-01

300

Ir/TaN as a bilayer diffusion barrier for advanced Cu interconnects  

SciTech Connect

The properties of an Ir (5 nm)/TaN (5 nm) stacked layer as a copper diffusion barrier on Si have been investigated. Ir/TaN bilayer barriers were prepared at room temperature by magnetron sputtering followed by in situ Cu deposition for diffusion tests. Thermal annealing of the barrier stacks was carried out in vacuum at high temperatures for 1 h. X-ray diffraction patterns, cross sectional transmission electron microscopy images, and energy-dispersive spectrometer line scans on the samples annealed at 600 deg. C revealed no Cu diffusion through the barrier. The results indicate that the Ir/TaN bilayer is an effective diffusion barrier for copper metallization.

Leu, L. C.; Norton, D. P. [Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611 (United States); McElwee-White, L. [Department of Chemistry, University of Florida, Gainesville, Florida 32611 (United States); Anderson, T. J. [Department of Chemical Engineering, University of Florida, Gainesville, Florida 32611 (United States)

2008-03-17

301

5Trifluoromethyl1,2-dimethyl-1H-pyrazolium chlorides: synthesis and 1 H , 13 C , 19 F and 35 Cl NMR chemical shifts  

Microsoft Academic Search

The one-pot synthesis of nine novel 5-trifluoromethyl-1,2-dimethyl-1H-pyrazolium chlorides 2 from the cyclocondensation of 4-alkoxy-1,1,1-trifluoro-3-alken-2-ones 1 [CF3C(O)CH=C(R1)OR, where R1=H, Me, n-Pr, n-Hex, Ph, 4-Me-C6H4, 4-F-C6H4, 4-Cl-C6H4, 4-NO2-C6H4, and R=Me, Et] with 1-2-dimethyl hydrazine, in quantitative yields, is reported. The 1H, 13C, 19F and 35Cl NMR chemical shifts of compounds 2 also are described.

Marcos A. P Martins; Rogério F Blanco; Claudio M. P Pereira; Paulo Beck; Sergio Brondani; Wilson Cunico; Nilo E. K Zimmermann; Helio G Bonacorso; Nilo Zanatta

2002-01-01

302

Mid-IR spectroscopy for rapid on-line analysis in heterogeneous catalyst testing  

Microsoft Academic Search

Instrumentation is reported for rapid, on-line quantitative analysis of the gaseous effluent from a heterogeneously catalyzed reaction. Absorption bands over the mid-infrared (IR) range 4000–580cm?1 have been used to quantify, in less than 2min, the major gaseous products of the hydrogenation of carbon monoxide (Fischer-Tropsch synthesis) using partial least squares (PLS) methodology. The fast analysis capability of the IR technique

Owen M Wilkin; Peter M Maitlis; Anthony Haynes; Michael L Turner

2003-01-01

303

Relationship between mutation of IR in the mtr system of neisseria gonorrhoeae and multiple antibiotic resistance  

Microsoft Academic Search

Summary  To study the relationship between mutation of the inverted repeat sequence (IR) in the multiple transferable resistant system\\u000a (mtr) of Neisseria gonorrhoeae (NG) and its multiple antibiotic resistance, minimal inhibitory concentrations (MICs) for the\\u000a clinically isolated strains were tested by agar-dilution-method. The mtr systems IR gene of NG was sequenced after amplification\\u000a by polymerase chain reaction (PCR). Either two susceptive

Zhang Lixia; Lin Nengxing; Huang Changzheng; Chen Hongxiang; Lin Yun; TU Yating

2006-01-01

304

Evaluation of CACNA1H in European patients with childhood absence epilepsy  

Microsoft Academic Search

CACNA1H was evaluated in a resource of Caucasian European patients with childhood absence epilepsy by linkage analysis and typing of sequence variants previously identified in Chinese patients. Linkage analysis of 44 pedigrees provided no evidence for a locus in the CACNA1H region and none of the Chinese variants were found in 220 unrelated patients.

Barry Chioza; Kate Everett; Harald Aschauer; Oebele Brouwer; Petra Callenbach; Athanasios Covanis; Olivier Dulac; Martina Durner; Orvar Eeg-Olofsson; Martha Feucht; Mogens Friis; Armin Heils; Marianne Kjeldsen; Katrin Larsson; Anna-Elina Lehesjoki; Rima Nabbout; Ingrid Olsson; Thomas Sander; Auli Sirén; Robert Robinson; Michele Rees; R. Mark Gardiner

2006-01-01

305

Complete Genome Sequence of the Arcobacter butzleri Cattle Isolate 7h1h.  

PubMed

Arcobacter butzleri strain 7h1h was isolated in the United Kingdom from the feces of a clinically healthy dairy cow. The genome of this isolate was sequenced to completion. Here, we present the annotation and analysis of the completed 7h1h genome, along with a comparison of this genome to the existing A. butzleri genomes. PMID:23969057

Merga, J Yvette; Winstanley, Craig; Williams, Nicola J; Yee, Emma; Miller, William G

2013-08-22

306

Studies towards rotational dynamics of dimethyl 2-(triphenylphosphoranylidene) succinate by 1H NMR  

NASA Astrophysics Data System (ADS)

We describe here the dynamic 1H NMR studies of dimethyl 2-(triphenylphosphoranylidene) succinate (1). Phosphorane 1 has a bond presenting slow (in the 1H NMR time scale) rotation which results in spectra of two isomers at the same time. From the spectral data were calculated the rate constant and thermodynamic parameters for the rotational process.

Rodrigues, Shirley M. M.; Palaretti, Vinicius; Nardini, Viviani; Constantino, Mauricio G.; da Silva, Gil Valdo J.

2013-11-01

307

High-resolution 1H MAS RFDR NMR of biological membranes  

NASA Astrophysics Data System (ADS)

The combination of magic angle spinning (MAS) with the high-resolution 1H NOESY NMR experiment is an established method for measuring through-space 1H1H dipolar couplings in biological membranes. The segmental motion of the lipid acyl chains along with the overall rotational diffusion of the lipids provides sufficient motion to average the 1H dipolar interaction to within the range where MAS can be effective. One drawback of the approach is the relatively long NOESY mixing times needed for relaxation processes to generate significant crosspeak intensity. In order to drive magnetization transfer more rapidly, we use solid-state radiofrequency driven dipolar recoupling (RFDR) pulses during the mixing time. We compare the 1H MAS NOESY experiment with a 1H MAS RFDR experiment on dimyristoylphosphocholine, a bilayer-forming lipid and show that the 1H MAS RFDR experiment provides considerably faster magnetization exchange than the standard 1H MAS NOESY experiment. We apply the method to model compounds containing basic and aromatic amino acids bound to membrane bilayers to illustrate the ability to locate the position of aromatic groups that have penetrated to below the level of the lipid headgroups.

Aucoin, Darryl; Camenares, Devin; Zhao, Xin; Jung, Jay; Sato, Takeshi; Smith, Steven O.

2009-03-01

308

Subcortical Ischemic Vascular Dementia: Assessment with Quantitative MR Imaging and 1H MR Spectroscopy  

Microsoft Academic Search

METHODS: Patients with dementia and lacunes (n 5 11), cognitive impairment and lacunes (n 5 14), and dementia without lacunes (n 5 18) and healthy age-matched control volunteers (n 5 20) underwent MR imaging and 1H MR spectroscopy. 1H MR spectroscopy data were coan- alyzed with coregistered segmented MR images to account for atrophy and tissue composition. RESULTS: Compared with

Aristides A. Capizzano; Norbert Schuff; Diane L. Amend; Jody L. Tanabe; David Norman; Andrew A. Maudsley; William Jagust; Helena C. Chui; George Fein; Mark R. Segal; Michael W. Weiner

309

Deformations of the Lie Algebras L1(H(2)) and L1(W(2)).  

National Technical Information Service (NTIS)

For the Lie algebras L1(H(2)) and L1(W(2)), infinitesimal deformations and the corresponding global ones are studied. It is shown that, as in the case of L1(W(1)), all infinitesimal deformations of L1(H(2)) and L1(W(2)) that are extendable to global defor...

N. Vandenhijligenberg Y. Kotchetkov G. Post

1992-01-01

310

Near-IR Photometry of Nova Del 2013  

NASA Astrophysics Data System (ADS)

Subjects: Infra-Red, Nova We report Near-IR photometry of Nova Del 2013 taken with the 0.76-m infrared telescope at the University of Minnesota's O'Brien Observatory (Marine on St. Croix, Minnesota, USA). RIJHKLM photometry were obtained on August 21.17 and 23.13 UT using an AsSi bolometer. Vega (alpha Lyrae) was used as the standard star. Our photometry show: August 21.17 UT: R = 5.1 +/- 0.1, I = 4.6 +/- 0.1, J = 4.6 +/- 0.1, H = 4.1 +/- 0.1, K = 3.9 +/- 0.1, L = 2.7 +/- 0.2, M = +2.2 +/- 0.2.

Cass, C. A.; Carlon, L. R.; Corgan, T. D.; Dykhoff, A. D.; Gehrz, D. R.; Shenoy, P. D.

2013-08-01

311

Fabrication of Ir-Based Electrodes by Metal Organic Chemical Vapor Deposition Using Liquid Ir Precursors  

NASA Astrophysics Data System (ADS)

Ir-based electrodes were fabricated by metal organic chemical vapor deposition (MOCVD) using a newly developed liquid precursor, (ethylcyclopentadienyl)bis(ethylene) iridium [Ir(EtCp)(C2H4)2], with a lower decomposition temperature than previous precursors, (ethylcyclopentadienyl)(1,5-cyclooctadiene) iridium [Ir(EtCp)(COD)] and (ethylcyclopentadienyl)(1,3-cyclohexadiene) iridium [Ir(EtCp)(CHD)]. Film growth behavior during MOCVD using Ir(EtCp)(C2H4)2 was investigated and compared with that using Ir(EtCp)(COD) and Ir(EtCp)(CHD). When Ir(EtCp)(C2H4)2 was used, significantly higher nucleation was observed at the initial growth stage than that using Ir(EtCp)(COD) and Ir(EtCp)(CHD) owing to the lower thermal decomposition temperature of 220 °C. Ir, IrO2 and Ir/IrO2 films were successfully prepared using Ir(EtCp)(C2H4)2 on underlying SiO2, TiN and Pb(Zr,Ti)O3, showing that Ir-based top and bottom electrodes can be fabricated by MOCVD. The root-mean-square surface roughnesses and electrical resistivities of Ir and IrO2 films on SiO2 were 2.2 nm and 9.4 ??\\cdotcm, and 3.3 nm and 1.8× 102 ??\\cdotcm, respectively. The step coverages of Ir films prepared at 230-400 °C were 35-45%.

Fujisawa, Hironori; Watari, Soichi; Iwamoto, Naoya; Shimizu, Masaru; Furukawa, Taishi; Kawano, Kazuhisa; Oshima, Noriaki

2006-09-01

312

IR+vacuum ultraviolet (118 nm) nonresonant ionization spectroscopy of methanol monomers and clusters: neutral cluster distribution and size-specific detection of the OH stretch vibrations.  

PubMed

Small methanol clusters are formed by expanding a mixture of methanol vapor seeded in helium and are detected using vacuum UV (vuv) (118 nm) single-photon ionization/linear time-of-flight mass spectrometer (TOFMS). Protonated cluster ions, (CH3OH)(n-1)H+ (n=2-8), formed through intracluster ion-molecule reactions following ionization, essentially correlate to the neutral clusters, (CH3OH)n, in the present study using 118 nm light as the ionization source. Both experimental and Born-Haber calculational results clarify that not enough excess energy is released into protonated cluster ions to initiate further fragmentation in the time scale appropriate for linear TOFMS. Size-specific spectra for (CH3OH)n (n=4 to 8) clusters in the OH stretch fundamental region are recorded by IR+vuv (118 nm) nonresonant ion-dip spectroscopy through the detection chain of IR multiphoton predissociation and subsequent vuv single-photon ionization. The general structures and gross features of these cluster spectra are consistent with previous theoretical calculations. The lowest-energy peak contributed to each cluster spectrum is redshifted with increasing cluster size from n=4 to 8, and limits near approximately 3220 cm(-1) in the heptamer and octamer. Moreover, IR+vuv nonresonant ionization detected spectroscopy is employed to study the OH stretch first overtone of the methanol monomer. The rotational temperature of the clusters is estimated to be at least 50 K based on the simulation of the monomer rotational envelope under clustering conditions. PMID:16422578

Fu, H B; Hu, Y J; Bernstein, E R

2006-01-14

313

IR+vacuum ultraviolet (118 nm) nonresonant ionization spectroscopy of methanol monomers and clusters: Neutral cluster distribution and size-specific detection of the OH stretch vibrations  

SciTech Connect

Small methanol clusters are formed by expanding a mixture of methanol vapor seeded in helium and are detected using vacuum UV (vuv) (118 nm) single-photon ionization/linear time-of-flight mass spectrometer (TOFMS). Protonated cluster ions, (CH{sub 3}OH){sub n-1}H{sup +} (n=2-8), formed through intracluster ion-molecule reactions following ionization, essentially correlate to the neutral clusters, (CH{sub 3}OH){sub n}, in the present study using 118 nm light as the ionization source. Both experimental and Born-Haber calculational results clarify that not enough excess energy is released into protonated cluster ions to initiate further fragmentation in the time scale appropriate for linear TOFMS. Size-specific spectra for (CH{sub 3}OH){sub n} (n=4 to 8) clusters in the OH stretch fundamental region are recorded by IR+vuv (118 nm) nonresonant ion-dip spectroscopy through the detection chain of IR multiphoton predissociation and subsequent vuv single-photon ionization. The general structures and gross features of these cluster spectra are consistent with previous theoretical calculations. The lowest-energy peak contributed to each cluster spectrum is redshifted with increasing cluster size from n=4 to 8, and limits near {approx}3220 cm{sup -1} in the heptamer and octamer. Moreover, IR+vuv nonresonant ionization detected spectroscopy is employed to study the OH stretch first overtone of the methanol monomer. The rotational temperature of the clusters is estimated to be at least 50 K based on the simulation of the monomer rotational envelope under clustering conditions.

Fu, H.B.; Hu, Y.J.; Bernstein, E.R. [Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523 (United States)

2006-01-14

314

catena-Poly[[chloridocadmium(II)]bis-{?-1-[(2-ethyl-1H-imidazol-1-yl)meth-yl]-1H-benzotriazole}[chloridocadmium(II)]di-?-chlorido  

PubMed Central

In the polymeric title complex, [CdCl2(C12H13N5)]n, the CdII atom is five-coordinated by two N atoms from two bridging 1-[(2-ethyl-1H-imidazol-1-yl)meth­yl]-1H-benzotriazole (bmei) ligands, two bridging Cl atoms and one terminal Cl atom in a distorted trigonal–bipyramidal geometry. The CdII atoms are connected alternately by the Cl atoms and bmei ligands, leading to a zigzag chain extending parallel to [011]. ?–? inter­actions, with a centroid–centroid distance of 3.3016?(3)?Å, help to stabilize the crystal packing.

Wang, Xia; Shi, Xian-Ju; Yang, Huai-Xia; Feng, Hu; Liu, Pan

2011-01-01

315

Oxygen induced nano-faceting of Ir(210)  

NASA Astrophysics Data System (ADS)

The adsorption of oxygen and the nanometer-scale faceting induced by oxygen have been studied on Ir(210) (I. Ermanoski, K. Pelhos, W. Chen, J. S. Quinton and T. E. Madey, Surface Science (2003) in press). Oxygen is found to chemisorb dissociatively on Ir(210) at room temperature and desorb molecularly at temperatures between 625K and 1500K. Using low energy electron diffraction (LEED) and scanning tunneling microscopy (STM), pyramid-shaped facets with 311 and (110) crystallographic orientations are found to form on the oxygen-covered Ir(210) surface when annealed to T>600K. The surface remains faceted for T<850 K. For T>850K, the substrate structure reverts to the oxygen-covered (210) planar state and does so reversibly, provided that oxygen is not lost due to desorption or via chemical reactions upon which the planar (210) structure remains. A clean faceted surface is prepared through the use of low temperature surface cleaning methods: Using CO oxidation, or reaction of hydrogen to form water, oxygen can be removed from the surface while preserving (freezing) the faceted structure. The resulting clean faceted surface remains stable for T<600K. For higher temperatures, the surface irreversibly relaxes to the planar state.

Ermanoski, Ivan; Chen, Wenhua; Madey, Theodore

2004-03-01

316

Complexes of IrIII-Octaethylporphyrin with Peptides as Probes for Sensing Cellular O2  

PubMed Central

IrIII–porphyrins are a relatively new group of phosphorescent dyes that have potential for oxygen sensing and labeling of biomolecules. The requirement of two axial ligands for the IrIII ion permits simple linkage of biomolecules by a one-step ligand-exchange reaction, for example, using precursor carbonyl chloride complexes and peptides containing histidine residue(s). Using this approach, we produced three complexes of IrIII–octaethylporphyrin with cell-penetrating (Ir1 and Ir2) and tumor-targeting (Ir3) peptides and studied their photophysical properties. All of the complexes were stable and possessed bright, long-decay (unquenched lifetimes exceeding 45 ?s) phosphorescence at around 650 nm, with moderate sensitivity to oxygen. The Ir1 and Ir2 complexes showed positive staining of a number of mammalian cell types, thus demonstrating localization similar to endoplasmic reticulum and ATP- and temperature-independent intracellular accumulation (direct translocation mechanism). Their low photo- and cytotoxicity allows intracellular oxygen to be probed.

Koren, Klaus; Dmitriev, Ruslan I; Borisov, Sergey M; Papkovsky, Dmitri B; Klimant, Ingo

2012-01-01

317

Complexes of Ir(III)-octaethylporphyrin with peptides as probes for sensing cellular O2.  

PubMed

Ir(III)-porphyrins are a relatively new group of phosphorescent dyes that have potential for oxygen sensing and labeling of biomolecules. The requirement of two axial ligands for the Ir(III) ion permits simple linkage of biomolecules by a one-step ligand-exchange reaction, for example, using precursor carbonyl chloride complexes and peptides containing histidine residue(s). Using this approach, we produced three complexes of Ir(III)-octaethylporphyrin with cell-penetrating (Ir1 and Ir2) and tumor-targeting (Ir3) peptides and studied their photophysical properties. All of the complexes were stable and possessed bright, long-decay (unquenched lifetimes exceeding 45 ?s) phosphorescence at around 650 nm, with moderate sensitivity to oxygen. The Ir1 and Ir2 complexes showed positive staining of a number of mammalian cell types, thus demonstrating localization similar to endoplasmic reticulum and ATP- and temperature-independent intracellular accumulation (direct translocation mechanism). Their low photo- and cytotoxicity allows intracellular oxygen to be probed. PMID:22532338

Koren, Klaus; Dmitriev, Ruslan I; Borisov, Sergey M; Papkovsky, Dmitri B; Klimant, Ingo

2012-04-24

318

Properties of the transition metal dichalcogenides: The case of IrS sub 2 and IrSe sub 2  

SciTech Connect

The syntheses and structure determination of IrSe{sub 2} and IrS{sub 2} were undertaken. Pure phases were obtained and powder data were measured on an X-ray diffractometer. Rietveld refinement was successfully carried out for both structures (IrSe{sub 2}, 269 observations R (weighted profile) 0.062; IrS{sub 2}, 205 observations R (weighted profile) 0.074). The Pnam space group (No. 62) was found to yield the best results, eliminating Pna2{sub 1} as the other possible space group considered in a previous study of IrSe{sub 2}. Chalcogen pairs are found in both structures and these may correspond, in a first approach, to the charge balance Ir{sup 3+}X{sup 2{minus}}(X{sub 2}){sup 2{minus}}{sub 1/2}. However, long bond lengths were found in the chalcogen pairs (S-S 2.299(11) {angstrom}, Se-Se 2.555(4) {angstrom}) along with an unexpectedly small effective cationic radius of 0.50 {angstrom} for Ir{sup 3+}. These features of IrS{sub 2} and IrSe{sub 2} are discussed.

Jobic, S.; Deniard, P.; Brec, R.; Rouxel, J. (Institut de Physique et Chimie des Materiaux, Nantes (France)); Drew, M.G.B. (The University, Reading (England)); David, W.I.F. (Rutherford Appleton Laboratory, Didcot (England))

1990-12-01

319

Structural and in vitro cytotoxicity studies on 1H-benzimidazol-2-ylmethyl-N-phenyl amine and its Pd(II) and Pt(II) complexes  

NASA Astrophysics Data System (ADS)

[MLCl 2]· zH 2O (L = (1H-benzimidazol-2-ylmethyl)-N-phenyl amine; M = Pd, z = 0; M = Pt, z = 1) and [PdL(OH 2) 2]·2X·zH 2O (X = Br, I, NO 3, z = 0; X = SCN, z = 1) complexes were synthesized as potential anticancer compounds and characterized by elemental analysis, spectral and thermal methods. FT-IR and 1H NMR studies revealed that the benzimidazole L is coordinated to the metal ions via the pyridine-type nitrogen (N py) of the benzimidazole ring and secondary amino group (NH sec). Quantum mechanical calculations of energies, geometries, vibrational wavenumbers, and 1H NMR of the benzimidazole L and its complexes were carried out by density functional theory using B3LYP functional combined with 6-31G(d) and LANL2DZ basis sets. Natural bond orbitals (NBOs) and frontier molecular orbitals were performed at B3LYP/LANL2DZ level of theory. The synthesized ligand, in comparison to its metal complexes was screened for its antibacterial activity. The benzimidazole L is more toxic against the bacterium Staphylococcus aureus (MIC = 58 ?g/mL) than the standard tetracycline (MIC = 82 ?g/mL). The complexes showed cytotoxicity against breast cancer, Colon Carcinoma, and human heptacellular Carcinoma cells. The platinum complex ( 6) displays cytotoxicity (IC 50 = 12.4 ?M) against breast cancer compared with that reported for cis-platin 9.91 ?M.

Abdel Ghani, Nour T.; Mansour, Ahmed M.

2011-10-01

320

Synthesis, multiple interactions and spectroscopy analysis of ethyl-4-[(benzoyl)-hydrazonomethyl]-3,5-dimethyl-1H-pyrrole-2-carboxylate: Through experimental and quantum chemical approaches  

NASA Astrophysics Data System (ADS)

The carboxaldehydes of pyrrole form important class of precursors for synthesis of acid hydrazide-hydrazones and their derivatives which show the various applications. A novel hydrazide-hydrazone of pyrrole: Ethyl-4-[(benzoyl)-hydrazonomethyl]-3,5-dimethyl-1H-pyrrole-2-carboxylate (3) has been synthesized by condensation of ethyl-4-formyl-3,5-dimetyl-1H-pyrrole-2-carboxylate and benzohydrazide. The product was characterized by spectroscopy methods (FT-IR, 1H NMR, UV-Vis and DART Mass) and quantum chemical calculations. The calculated thermodynamic parameters show that the formation of (3) is exothermic and spontaneous at room temperature. The local electronic descriptors analysis and molecular electrostatic potential surface were used to predict the sites and nature of interactions which indicate the dimer formation through multiple interaction through NH\\ctdot O and C-H\\ctdot O. The vibrational analysis shows red shifts in vNH and vCO as result of dimer formation. Topological and energetic parameters generated by AIM show the nature of interactions in dimer. The interaction energies of dimer formation using DFT and AIM calculations are found to be 14.19 and 15.19 kcal/mol respectively. Ellipticity analysis confirms the presence of resonance assisted heteronuclear H-bonding in dimer.

Singh, R. N.; Kumar, Amit; Tiwari, R. K.; Rawat, Poonam

2013-03-01

321

Synthesis, spectroscopic characterization, X-ray structure and DFT studies on 2,6-bis(1-benzyl-1H-benzo[d]imidazol-2-yl)pyridine  

NASA Astrophysics Data System (ADS)

The title molecule, 2,6-bis(1-benzyl-1H-benzo[d]imidazol-2-yl)pyridine (C33H25N5), was synthesized and characterized by elemental analysis, FT-IR spectroscopy, one- and two-dimensional NMR spectroscopies, and single-crystal X-ray diffraction. In addition, the molecular geometry, vibrational frequencies and gauge-independent atomic orbital (GIAO) 1H and 13C NMR chemical shift values of the title compound in the ground state have been calculated using the density functional theory at the B3LYP/6-311G(d,p) level, and compared with the experimental data. The complete assignments of all vibrational modes were performed by potential energy distributions using VEDA 4 program. The geometrical parameters of the optimized structure are in good agreement with the X-ray crystallographic data, and the theoretical vibrational frequencies and GIAO 1H and 13C NMR chemical shifts show good agreement with experimental values. Besides, molecular electrostatic potential (MEP) distribution, frontier molecular orbitals (FMO) and non-linear optical properties of the title compound were investigated by theoretical calculations at the B3LYP/6-311G(d,p) level. The linear polarizabilities and first hyper polarizabilities of the molecule indicate that the compound is a good candidate of nonlinear optical materials. The thermodynamic properties of the compound at different temperatures were calculated, revealing the correlations between standard heat capacity, standard entropy, standard enthalpy changes and temperatures.

?nkaya, Ersin; Günnaz, Salih; Özdemir, Nam?k; Dayan, Osman; Dinçer, Muharrem; Çetinkaya, Bekir

2013-02-01

322

Heterocyclic analogues of xanthone and xanthione. 1H-pyrano[2,3-c:6,5-c]dipyrazol-4(7H)-ones and thiones: synthesis and NMR data.  

PubMed

The synthesis of the title compounds is described. Reaction of 1-substituted 2-pyrazolin-5-ones with 5-chloro-1-phenyl-1H-pyrazole-4-carbonyl chloride or 5-chloro-3-methyl-1-phenyl-1H-pyrazole-4-carbonyl chloride, respectively, using calcium hydroxide in refluxing 1,4-dioxane gave the corresponding 4-heteroaroylpyrazol-5-ols, which were cyclized into 1H-pyrano[2,3-c:6,5-c]dipyrazol-4(7H)-ones by treatment with K2CO3/DMF. The latter were converted into the corresponding thiones upon reaction with Lawesson's reagent. Detailed NMR spectroscopic investigations (1H, 13C, 15N) of the ring systems and their precursors are presented. PMID:20877210

Datterl, Barbara; Tröstner, Nicole; Kucharski, Dorota; Holzer, Wolfgang

2010-09-01

323

Chemical models for the contracting W3 IRS4  

NASA Astrophysics Data System (ADS)

We have studied the chemical evolution in the central core of a contracting cloud representing W3 IRS4. We modified the equation of temperature to satisfy the physical conditions of W3 IRS4. The chemical rate equations and the hydrodynamics are integrated simultaneously. The contraction is followed from a very low density of n = 10 cm^ - 3 to high core density of n = 10^6 cm^ - 3. The chemical evolution is studied for various chemical conditions including both the effects of varying cosmic ray ionization rate and the effect of ion-dipole molecule collisions.The main results by using the more extensive chemical network with the most updating reaction rates show that the calculated fractional abundances are in agreement with observation at intermediate and enhanced cosmic ray ionization rate at high depletion of elemental atoms.

Amin, Magdy Y.

2000-12-01

324

Identification of Lactam-Lactim Tautomers of Aromatic Heterocycles in Aqueous Solution Using 2D IR Spectroscopy  

PubMed Central

The tautomerism of aromatic heterocycles is of great interest because it directly affects their chemical properties and biological function. The tautomerism of 2-pyridone, 6-chloro-2-pyridone, and 4-pyrimidinone have been examined in D2O using FTIR, two-dimensional IR (2D IR) spectroscopy and density functional theory (DFT) calculations. Using the 2D IR cross-peak patterns, the lactim tautomer of 6-chloro-2-pyridone was separated from the lactam tautomer, and its population was observed to increase with temperature. The equilibrium constant of [lac-tam]/[lactim] was determined to be 2.1 at room temperature for 6-chloro-2-pyridone. Similarly, the N1H and N3H lactam tautomers of 4-pyrimidinone were identified with 2D IR. To assign the vibrational modes of different tautomers, DFT calculations of these chemical species were performed with explicit water molecules, and the hydration effects on the vibrational frequencies and intensities were established.

Peng, Chunte Sam; Tokmakoff, Andrei

2012-01-01

325

Magnetorheological finishing of IR materials  

NASA Astrophysics Data System (ADS)

Magnetorheological finishing (MRF) is a subaperture lap, deterministic process developed at the Center for Optics Manufacturing. MRF can remove subsurface damage from an optical component while correcting figure errors and smoothing small scale microroughness. The 'standard' magnetorheological fluid for finishing of optical glasses consists of magnetic carbonyl iron and nonmagnetic cerium oxide particles in water. This composition works well for a variety of soft and hard glass types, but it does not perform adequately for certain single crystal materials and polycrystalline compounds used in IR applications. In this paper, we describe modifications to MRF and finishing experiments for LiF, ZnSe, CaF2, AMTIR-1, ZnS, MgF2, sapphire, and CVD diamond.

Jacobs, Stephen D.; Yang, Fuqian; Fess, E.; Feingold, J. B.; Gillman, Birgit E.; Kordonski, V. W.; Edwards, H.; Golini, Donald

1997-10-01

326

MCT IR detectors in France  

NASA Astrophysics Data System (ADS)

This paper describes the status of MCT IR technology in France at Leti and Sofradir. This concerns first evolution of crystal growth of large CZT for substrates, and MCT epilayers grown by LPE and MBE. A focus will be made on extrinsic doping of MCT with Indium and Arsenic for device fabrication. Evolution of detector technology will also be considered for detectors that operate from NIR/SWIR to VLWIR, moving from an n on p vacancy doped technology to a fully extrinsically doped p on n device architecture. Last results on 3rd generation detectors such as multicolor FPAs, HOT detectors and 2D or 3D FPAs that use MCT APD will also be described. Moving to larger FPAs, pixel pitch reduction become mandatory and technology evolution to achieve this goal will be presented .Then, cost reduction achievement through more compact systems that operate at higher temperature and/or integrate optical functions inside the cryostat will also be considered.

Destéfanis, Gérard; Tribolet, Philippe; Vuillermet, Michel; Billon Lanfrey, David

2011-05-01

327

Vibrational and electronic absorption spectral studies of 5-amino-1-(4-bromophenyl)-3-phenyl-1-H-pyrazole  

NASA Astrophysics Data System (ADS)

The FT-IR and FT-Raman spectra of 5-amino-1-(4-bromophenyl)-3-phenyl-1-H-pyrazole have been measured in the regions 4000-400 cm-1 and 3500-100 cm-1, respectively. The equilibrium geometry, bonding features and harmonic vibrational frequencies have been carried out with the help of DFT method. The assignments of the vibrational spectra have been carried out with the normal coordinate analysis (NCA) following the scaled quantum mechanical force field methodology (SQMFF). The first-order hyperpolarizability (?0) and related properties (?, ?0, and ??) of 5A4BP3PP are calculated by using HF/6-31G(d,p) method on the finite field approach. Stability of the molecule arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bonding orbital (NBO) analysis. The results show that electron density (ED) in the ?* and ?* antibonding orbitals and second order delocalization energies E(2) confirms the occurrence of the intramolecular charge transfer (ICT) within the molecule. UV-vis spectrum of the compound was recorded and the electronic properties, such as HOMO and LUMO energies, were performed by TDDFT using 6-31G(d,p). The HOMO-LUMO calculations indicating the charge transfer takes place within the molecule.

Prasad, M. V. S.; Chaitanya, Kadali; Udaya Sri, N.; Veeraiah, V.

2012-12-01

328

Synthesis and biological activity of novel 1-substituted phenyl-4-[N-[(2'-morpholinothoxy)phenyl]aminomethyl]-1H-1,2,3-triazoles.  

PubMed

In an attempt to search for potent antifungal agents, a series of novel 1-substituted phenyl-4-[N-[(2'-morpholinothoxy)phenyl]aminomethyl]-1H-1,2,3-triazoles 5a-m was designed and synthesized via Huisgen cycloaddition reaction between various (2-morpholinoethoxy)-N-(prop-2-ynyl)aniline and different azidobenzene. Their chemical structures were characterized by (1) H NMR and elemental analysis. A cleaner reaction with milder conditions and satisfactory yields was observed in the micorwave-assisted synthesis of 4a-c. The fungicidal activity of some target compounds were evaluated in vitro against Fusarium omysporum, Physalospora piricola, Alternaria solani, Cercospora arachidicola and Gibberella zeae at 50 ?g/mL. The bioassay results indicated that some compounds exhibited moderate fungicidal activities. Furthermore, compound 5h displayed equal activity to the positive control compounds against Alternaria solani. PMID:21736703

Mao, Ming-Zhen; Li, Yu-Xin; Zhou, Yun-Yun; Chen, Wei; Liu, Tuan-Wei; Yu, Shu-Jing; Wang, Su-Hua; Li, Zheng-Ming

2011-08-03

329

1H NMR observation of the critical slowing down in ammonium chloride  

NASA Astrophysics Data System (ADS)

We have studied the ? transition in ammonium chloride (NH4Cl) by means of 1H NMR. In previous reports, the 1H NMR spin-lattice relaxation time (T1) did not show the critical slowing down, whereas the Cl35 NMR spin-lattice relaxation time revealed a sharp ? transition at the critical temperature. Our measurements of the 1H solid echo decay constant (T2E) and the second moment near the critical temperature manifest the critical slowing down, and the temperature dependence of the T2E is well explained by the dynamic Ising model.

Lee, K. W.; Lee, C. H.; Lee, C. E.; Kang, J. K.

1995-12-01

330

Monitoring the enzymatic degradation of sinigrin from B. juncea meal using (1)H NMR spectroscopy.  

PubMed

A simple procedure for extracting and purifying sinigrin from Oriental mustard (Brassica juncea) meal using cold water was developed. Subsequently, the chemical degradation of sinigrin due to enzymatic activity was monitored using (1)H NMR spectroscopy over the course of 30 h. The experimental findings show that sinigrin has been positively identified from B. juncea using (1)H NMR spectroscopy and the prescribed preparation procedure. The results that have been presented also offer unambiguous evidence that (1)H NMR spectroscopy can be used to detect changes in sinigrin concentration over time. PMID:20013469

Belliveau, Kody A; Romero-Zerón, Laura B

2010-01-01

331

UV\\/Vis, IR and 1H NMR spectrophotometric studies of some bisazo-dianil compounds based on bis-(hydroxy, formyl) phenylazo phenylene and anthranilic acid  

Microsoft Academic Search

The electronic absorption spectra of some bisazo-dianils are studied in organic solvents of different polarity and in buffer solutions of varied pH. The different absorption bands are assigned to the corresponding electronic transitions, the solvent effect on the CT band energy is also discussed. The spectral study in buffer solutions is utilized for the determination of the pKa of the

Raafat M. Issa; Kamal Y. El-baradie; Nadia A. El-Wakiel

2004-01-01

332

Investigation of ethylene oxide oligomerization during functionalization of poly(butadienyl)lithium using MALDI-TOF MS and 1H NMR analyses  

Microsoft Academic Search

Oligomerization of ethylene oxide during the functionalization of poly(butadienyl)lithium in benzene and cyclohexane at 25 °C has been investigated by MALDI-TOF MS and 1H NMR. Chemically significant amounts of oligomer were found using 4equiv. of ethylene oxide ([EO]\\/[PLi]) after 12 h in both benzene and cyclohexane. No oligomer was observed when the reaction time was minimized.

Roderic P. Quirk; Ya Guo; Chrys Wesdemiotis; Mark A. Arnould

2004-01-01

333

REGIOSELECTIVE SYNTHESIS OF EITHER 1H- OR 2H-1,2,3- TRIAZOLES VIA MICHAEL ADDITION TO ?,ss-UNSATURATED KETONES  

PubMed Central

The Michael reaction of NH-1,2,3-triazole (1) with ?,?-unsaturated ketones was studied. 1H-1,2,3-triazolyl-ketones were selectively generated when 1 was combined neat with a variety of enones. The use of aprotic solvents with catalytic base gave the corresponding 2H-regioisomers. Together, these two protocols provide direct access to either the N1- or N2-substituted 1,3-triazolyl ketone regioisomers.

Kwok, Sen Wai; Hein, Jason E.; Fokin, Valery V.; Sharpless, K. Barry

2009-01-01

334

Cross sections and Rosenbluth separations in 1H(e, e'K+)Lambda up to Q2=2.35 GeV2  

Microsoft Academic Search

The kaon electroproduction reaction 1H(e,e'K+)Lambda was studied as a function of the virtual-photon four-momentum, Q2, total energy, W, and momentum transfer, t, for different values of the virtual- photon polarization parameter. Data were taken at electron beam energies ranging from 3.40 to 5.75 GeV. The center of mass cross section was determined for 21 kinematics corresponding to Q2 of 1.90

M. Coman; P. Markowitz; K. A. Aniol; K. Baker; W. U. Boeglin; H. Breuer; P. Bydzovsky; A. Camsonne; J. Cha; C. Chang; N. Chant; J.-P. Chen; E. A. Chudakov; E. Cisbani; L. Cole; F. Cusanno; C. W. de Jager; R. De Leo; A. P. Deur; S. Dieterich; F. Dohrmann; D. Dutta; R. Ent; O. Filoti; K. Fissum; S. Frullani; F. Garibaldi; O. Gayou; F. Gilman; J. Gomez; P. Gueye; J. O. Hansen; D. W. Higinbotham; W. Hinton; T. Horn; B. Hu; G. M. Huber; M. Iodice; C. Jackson; X. Jiang; M. Jones; K. Kanda; C. Keppel; P. King; F. Klein; K. Kozlov; K. Kramer; L. Kramer; L. Lagamba; J. J. LeRose; N. Liyanage; D. J. Margaziotis; S. Marrone; K. McCormick; R. W. Michaels; J. Mitchell; T. Miyoshi; S. Nanda; M. Palomba; V. Pattichio; C. F. Perdrisat; E. Piasetzky; V. A. Punjabi; B. Raue; J. Reinhold; B. Reitz; R. E. Roche; P. Roos; A. Saha; A. J. Sarty; Y. SATO; S. Sirca; M. Sotona; L. Tang; H. Ueno; P. E. Ulmer; G. M. Urciuoli; A. Uzzle; A. Vacheret; K. Wang; K. Wijesooriya; B. Wojtsekhowski; S. Wood; I. Yaron; X. Zheng; L. Zhu

2010-01-01

335

2-Chloro-N-[1-(4-chloro-phen-yl)-3-cyano-1H-pyrazol-5-yl]acetamide  

PubMed Central

The title compound, C12H8Cl2N4O, was synthesized by the reaction of 5-amino-1-(4-chloro­phen­yl)-1H-pyrazole-3-carbonitrile and 2-chloro­acetyl chloride. The dihedral angle between the pyrazole and benzene rings is 30.7?(3)°. In the crystal structure, strong N—H?O hydrogen bonds link the mol­ecules into chains along [001]. C—H?N hydrogen bonds are also present.

Mu, Hai-ping; Yang, Yang; Jiang, Qiang-hua; Fu, Xiao-dong; Wan, Rong

2012-01-01

336

Ultrasound-assisted one-pot, three-component synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-diones.  

PubMed

Triethylamine was found to be an efficient catalyst for the synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-diones by one-pot reaction of phthalhydrazide, aromatic aldehydes, and malononitrile or ethyl cyanoacetate in ethanol under ultrasonic irradiation. The advantages of this method are the use of an inexpensive and readily available catalyst, easy workup, improved yields, and the use of ethanol as a solvent that is considered to be relatively environmentally benign. PMID:19589715

Nabid, Mohammad Reza; Rezaei, Seyed Jamal Tabatabaei; Ghahremanzadeh, Ramin; Bazgir, Ayoob

2009-06-18

337

Absence of structural transition in M0.5IrTe2 (M = Mn, Fe, Co, Ni)  

NASA Astrophysics Data System (ADS)

M-doped IrTe2 (M = Mn, Fe, Co, Ni) compounds were synthesized by solid-state reaction. Single crystal x-ray diffraction experiments indicate that part of the doped M ions (M = Fe, Co, and Ni) substitute for Ir, and the rest intercalate into the octahedral interstitial sites located in between IrTe2 layers. Due to the lattice mismatch between MnTe2 and IrTe2, Mn has limited solubility in IrTe2 lattice. The trigonal structure is stable in the whole temperature range 1.80 K? T ? 300 K for all doped compositions. No long-range magnetic order or superconductivity was observed in any doped compositions above 1.80 K. A spin glass behavior below 10 K was observed in Fe-doped IrTe2 from the temperature dependence of magnetization, electrical resistivity, and specific heat. The low temperature specific heat data suggest the electron density of states is enhanced in Fe- and Co-doped compositions but reduced in Ni-doped IrTe2. With the 3d transition metal doping the trigonal a-lattice parameter increases but the c-lattice parameter decreases. Detailed analysis of the single crystal x-ray diffraction data shows that interlayer Te-Te distance increases despite a reduced c lattice. The importance of the Te-Te, Te-Ir, and Ir-Ir bonding is discussed.

Yan, J.-Q.; Saparov, B.; Sefat, A. S.; Yang, H.; Cao, H. B.; Zhou, H. D.; Sales, B. C.; Mandrus, D. G.

2013-10-01

338

Fabrication of Ir-Based Electrodes by Metal Organic Chemical Vapor Deposition Using Liquid Ir Precursors  

Microsoft Academic Search

Ir-based electrodes were fabricated by metal organic chemical vapor deposition (MOCVD) using a newly developed liquid precursor, (ethylcyclopentadienyl)bis(ethylene) iridium [Ir(EtCp)(C2H4)2], with a lower decomposition temperature than previous precursors, (ethylcyclopentadienyl)(1,5-cyclooctadiene) iridium [Ir(EtCp)(COD)] and (ethylcyclopentadienyl)(1,3-cyclohexadiene) iridium [Ir(EtCp)(CHD)]. Film growth behavior during MOCVD using Ir(EtCp)(C2H4)2 was investigated and compared with that using Ir(EtCp)(COD) and Ir(EtCp)(CHD). When Ir(EtCp)(C2H4)2 was used, significantly higher nucleation was

Hironori Fujisawa; Soichi Watari; Naoya Iwamoto; Masaru Shimizu; Taishi Furukawa; Kazuhisa Kawano; Noriaki Oshima

2006-01-01

339

Epitaxial cobalt oxide films on Ir(100)-the importance of crystallographic analyses.  

PubMed

Epitaxial cobalt oxide films on Ir(100) exhibit a rich scenario of different structural phases which are reviewed in this paper. The great majority of phases could be, as a rare case, crystallographically described by the joint application of atomically resolved STM and quantitative LEED, whereby structural surprises were more the rule than the exception. So, the oxide grows in the polar (111) orientation for both the Co3O4 and CoO stoichiometry on the bare Ir substrate in spite of the latter's square symmetry. Moreover, the film orientation can be tuned to non-polar (100) growth when one or several pseudomorphic Co layers are introduced as an interface between oxide and Ir substrate. By using the nanostructured Ir(100)-(5 × 1)-H phase as a template a nanostructured Co film can be formed whose oxidation leads to a nanostructured oxide. The nominally polar films circumvent the polarity problem by appropriate surface terminations. That of CoO(111) is, again as a surprise, realized by a switch from rocksalt-type to wurtzite-type stacking near the surface, by which the latter becomes metallic. The stepwise oxidation of a pseudomorphic Co layer on the bare Ir substrate leads to the sequential formation of rocksalt-type tetrahedral Co-O building blocks (with intermediate BN-type blocks) whereby the Co species more and more assume positions determined by the inner-oxidic binding. PMID:23535176

Heinz, K; Hammer, L

2013-03-27

340

New supersymmetric quartet of nuclei: {sup 192,193}Os-{sup 193,194}Ir  

SciTech Connect

We present evidence for the existence of a new supersymmetric quartet of nuclei in the A{approx}190 mass region. The analysis is based on new experimental information on the odd-odd nucleus {sup 194}Ir from transfer and neutron capture reactions. The new data allow the identification of a new supersymmetric quartet, consisting of the {sup 192,193}Os and {sup 193,194}Ir nuclei. We make explicit predictions for {sup 193}Os, and suggest that its spectroscopic properties be measured in dedicated experiments. Finally, we study correlations between different transfer reactions.

Bijker, R.; Frank, A. [ICN-UNAM, AP 70-543, 04510 Mexico DF (Mexico); Barea, J. [Center for Theoretical Physics, Sloane Physics Laboratory, Yale University, P.O. Box 208210, New Haven, Connecticut 06520-8120 (United States); Graw, G.; Wirth, H.-F. [Sektion Physik, Ludwig-Maximilians-Universitaet Muenchen, D-85748 Garching (Germany); Hertenberger, R. [Fakultaet fuer Physik, Ludwig-Maximilians-Universitaet Muenchen, D-85748 Garching (Germany); Jolie, J. [Institut fuer Kernphysik, Universitaet zu Koeln, D-50937 Koeln (Germany)

2009-01-28

341

1H NMR, a rapid method to monitor organic acids during cupuassu (Theobroma grandiflorum Spreng) processing.  

PubMed

The development of an analytical method using 1H nuclear magnetic resonance (1H NMR) spectrometry to monitor cupuassu (Theobroma grandiflorum Spreng) bean fermentation, drying, and roasting processes is reported. The analysis of organic acids and alcohols of crude water extracts of cupuassu ground kernels were monitored by HPLC and 1H NMR spectroscopy. The residual protein signals caused deleterious effects on acid and alcohol quantifications. Therefore, the analytical procedures were optimized by sample cleanup and water suppression pulse sequences in order to obtain compatible data using HPLC and 1H NMR. The quantification of lactic acid, acetic acid, and 2,3-butanediol by NMR is 5- to 10-fold faster than by HPLC, with the advantage of providing the identification of several chemical species in a single experiment. Application of these analytical conditions to some cupuassu samples revealed that this methodology can be applied to the quality profiles of fermentation and roasting processes. PMID:16756332

Figueiredo, Isis M; Pereira, Nadia R; Efraim, Priscilla; García, Nelson H P; Rodrigues, Nadia R; Marsaioli, Antônio; Marsaioli, Anita J

2006-06-14

342

2-{(R)-2-methylpyrrolidin-2-yl)-1H-benzimidazole-4-carboxamide crystalline form 2  

US Patent & Trademark Office Database

2-((R)-2-Methylpyrrolidin-2-yl)-1H-benzimidazole-4-carboxamide Crystalline Form 2, ways to make it, compositions comprising it and made using it, and methods of treating patients having disease using it are disclosed.

2011-09-06

343

Iridium(III) emitters based on 1,4-disubstituted-1H-1,2,3-triazoles as cyclometalating ligand: synthesis, characterization, and electroluminescent devices.  

PubMed

A series of blue and blue-green emitters based on neutral bis- and tris-cyclometalated Ir(III) complexes with 1-benzyl-4-(2,6-difluorophenyl)-1H-1,2,3-triazole (dfptrBn) as cyclometalating ligand is reported. The bis-cyclometalated complexes of the type [Ir(dfptrBn)(2)(L(^)X)] with different ancillary ligands, L(^)X = picolinate (pic) (2) or 2-(5-(perfluorophenyl)-2H-1,2,4-triazol-3-yl)pyridine (pytrF(5)) (3), are described and their photophysical properties compared with the analogous complexes containing the archetypal 2-(2,4-difluorophenyl)pyridinato (dfppy) as cyclometaled ligand (C(^)N). Complex 2 exhibits a marked solvatochromic behavior, from 475 nm in toluene to 534 nm in formamide, due to the strong MLCT character of its emissive excited state. Complex 3 displays a true-blue emission, narrower in the visible part than FIrpic. In addition, the homoleptic complex [Ir(dfprBn)(3)] (4) and the heteroleptic compounds with mixed arylpyridine/aryltriazole ligands, [Ir(dfptrBn)(2)(C(^)N)] (C(^)N = 2-phenylpyridinato (ppy) (5) or dfppy (6)), have been synthesized and fully characterized. The facial (fac) complex fac-4 is emissive at 77 K showing a deep-blue emission, but it is not luminescent in solution at room temperature similarly to their phenylpyrazole counterparts. However, the fac isomers, fac-5 and fac-6, are highly emissive in solution and thin films, reaching emission quantum yields of 76%, with emission colors in the blue to blue-green region. The photophysical properties for all complexes have been rationalized by means of quantum-chemical calculations. In addition, we constructed electroluminescent devices, organic light-emitting diodes (OLEDs) by sublimation of fac-6, and by solution processed polymer-based devices (PLEDs) using complexes fac-5 or fac-6 as dopants. PMID:23383706

Fernández-Hernández, Jesús M; Beltrán, Juan I; Lemaur, Vincent; Gálvez-López, Maria-Dolores; Chien, Chen-Han; Polo, Federico; Orselli, Enrico; Fröhlich, Roland; Cornil, Jérôme; De Cola, Luisa

2013-02-05

344

Cerebral glutamine metabolism under hyperammonemia determined in vivo by localized 1H and 15N NMR spectroscopy  

PubMed Central

Brain glutamine synthetase (GS) is an integral part of the glutamate–glutamine cycle and occurs in the glial compartment. In vivo Magnetic Resonance Spectroscopy (MRS) allows noninvasive measurements of the concentrations and synthesis rates of metabolites. 15N MRS is an alternative approach to 13C MRS. Incorporation of labeled 15N from ammonia in cerebral glutamine allows to measure several metabolic reactions related to nitrogen metabolism, including the glutamate–glutamine cycle. To measure 15N incorporation into the position 5N of glutamine and position 2N of glutamate and glutamine, we developed a novel 15N pulse sequence to simultaneously detect, for the first time, [5-15N]Gln and [2-15N]Gln+Glu in vivo in the rat brain. In addition, we also measured for the first time in the same experiment localized 1H spectra for a direct measurement of the net glutamine accumulation. Mathematical modeling of 1H and 15N MRS data allowed to reduce the number of assumptions and provided reliable determination of GS (0.30±0.050??mol/g per minute), apparent neurotransmission (0.26±0.030??mol/g per minute), glutamate dehydrogenase (0.029±0.002??mol/g per minute), and net glutamine accumulation (0.033±0.001??mol/g per minute). These results showed an increase of GS and net glutamine accumulation under hyperammonemia, supporting the concept of their implication in cerebral ammonia detoxification.

Cudalbu, Cristina; Lanz, Bernard; Duarte, Joao MN; Morgenthaler, Florence D; Pilloud, Yves; Mlynarik, Vladimir; Gruetter, Rolf

2012-01-01

345

The identification of vicinally substituted cyclohexane isomers in their mixtures by 1H and 13C NMR spectroscopy  

NASA Astrophysics Data System (ADS)

The radical addition reactions of organobromine compounds, XBr (X=CH 2COOMe, PhCH 2, CHBr 2 and CCl 3) with cyclohexene afforded mixtures of cis/ trans isomer pairs of 1-X-2-Br-cyclohexanes. In addition to benzyl benzoyloxy derivatives are formed also, when benzoyl peroxide is used as an initiator. Owing to the great difficulties in separating these cis/ trans isomer pairs, they are identified directly in their mixtures by NMR spectroscopy. In addition to one-dimensional (1D) 1H, proton decoupled 13C and DEPT-135, also two-dimensional (2D) 13C- 13C INADEQUATE as well as 1H- 13C HMQC experiments have been used in assigning the signals of each compound in their mixtures. The identification of each isomer was based on comparison of experimental 3JH,H coupling constants with theoretical ones based on the well-known Karplus type relationship. The more stable conformation for each isomer was estimated using the semiempirical AM1 molecular orbital method. The calculations support the isomer pair elucidations.

Laihia, Katri; Kolehmainen, Erkki; Nevalainen, Tapio; Kauppinen, Reijo; Vasilieva, Tamara T.; Terentiev, Alexander B.

2000-02-01

346

1H-NMR spectroscopy of body fluids: inborn errors of purine and pyrimidine metabolism  

Microsoft Academic Search

Background: The diagnosis of inborn errors of purine and pyrimidine metabolism is often difficult. We exam- ined the potential of 1H-NMR as a tool in evaluation of patients with these disorders. Methods: We performed 1H-NMR spectroscopy on 500 and 600 MHz instruments with a standardized sample volume of 500 mL. We studied body fluids from 25 patients with nine inborn

Ron A. Wevers; Udo F. H. Engelke; Sytske H. Moolenaar; Christa Brautigam; Jong de J. G. N; Ries Duran; Abreu de R. A; Gennip van A. H

1999-01-01

347

Application of the multi-standard methodology for calculating 1H NMR chemical shifts.  

PubMed

Gauge including atomic orbitals (GIAO) (1)H NMR chemical shift calculations have been performed for 66 organic compounds at 72 different levels of theory using the multi-standard approach (MSTD) previously developed for (13)C NMR. This straightforward computational technique involves the combination of methanol and benzene as standards. The studied methodology has been shown to predict (1)H NMR chemical shifts efficiently at different levels of theory. PMID:22713105

Sarotti, Ariel M; Pellegrinet, Silvina C

2012-07-03

348

Molality as a unit of measure for expressing 1H MRS brain metabolite concentrations in vivo  

Microsoft Academic Search

Absolute concentrations of cerebral metabolite in in vivo1H magnetic resonance spectroscopy studies (1H-MRS) are widely reported in molar units as moles per liter of tissue, or in molal units as moles per kilogram of tissue. Such measurements require external referencing or assumptions as to local water content. To reduce the scan time, avoid assumptions that may be invalid under specific

Jack Knight-Scott; Andreana P. Haley; Sarah R. Rossmiller; Elana Farace; Vu M. Mai; John M. Christopher; Carol A. Manning; Virginia I. Simnad; Helmy M. Siragy

2003-01-01

349

15 N–{ 1 H} NOE experiment at high magnetic field strengths  

Microsoft Academic Search

The heteronuclear 15N–{1H} NOE values are typically determined by taking the ratio of 15N signal intensities recorded in the presence and absence of 1H saturation prior to evolution of 15N magnetization. Since the intensity ratio of two independent experiments is taken, complete recovery of 15N magnetization during the scan repetition delay is critical to obtain reliable NOE values. Because it

Qingguo Gong; Rieko Ishima

2007-01-01

350

[Brain metabolism alterations in patients with anorexia nervosa observed in 1H-MRS  

Microsoft Academic Search

The causes of metabolic brain changes in patients with anorexia nervosa are still not fully explained. The purpose of this study was to use the 1H-MRS method in investigating metabolic changes in the brain of patients with anorexia nervosa. We studied 10 patients for visible alternations in brain metabolism and compared the results to healthy controls. 1H-MRS was acquired by

P. Grzelak; W. Gajewicz; A. Wyszogrodzka-Kucharska; A. Rotkiewicz; L. Stefanczyk; B. M. Goraj; J. Rabe-Jablonska

2005-01-01

351

Synthesis of a 2(1H)-pyridone library via rhodium catalyzed formation of isomunchones.  

PubMed

Through the use of the dipolar cycloaddition of isomunchones with olefins the 2(1H)-pyridone ring system has been synthesized.1 The use of different cyclization partners followed by diversification of the initial scaffold has provded libraries of 4-hydroxy-2(1H)-pyridones. There are no examples of this ring system in either PubChem or the MLSMR. PMID:23742807

De, Subhasis; Chen, Lu; Zhang, Shuxing; Gilbertson, Scott Richard

2013-06-01

352

Spatially Localized 1H NMR Spectra of Metabolites in the Human Brain  

Microsoft Academic Search

Using a surface coil, we have obtained 1H NMR spectra from metabolites in the human brain. Localization was achieved by combining depth pulses with imageselected in vivo spectroscopy magnetic field gradient methods. 1H spectra in which total creatine (3.03 ppm) has a signal\\/noise ratio of 95:1 were obtained in 4 min from 14 ml of brain. A resonance at 2.02

C. C. Hanstock; D. L. Rothman; J. W. Prichard; T. Jue; R. G. Shulman

1988-01-01

353

Evidence for long-term neurotoxicity associated with methamphetamine abuse A 1H MRS study  

Microsoft Academic Search

Article abstract—Objective: To determine whether proton MRS (1H MRS) can detect long-term metabolite abnormalities in abstinent methamphetamine users. Background: Methamphetamine is toxic to dopaminergic and serotonergic neurons in rodents; however, little data are available on the toxic effects of methamphetamine on the human brain. Methods: 1H MRS was performed in 26 abstinent methamphetamine abusers with a history of methamphetamine dependence

Thomas Ernst; Linda Chang; Maria Leonido-Yee; Oliver Speck

354

Role of IRS1 and IRS2 in Modulating ErbB-induced Tumorigenesis.  

National Technical Information Service (NTIS)

Previous studies suggested that the adapter proteins IRS1 and IRS2 may interact with ErbB1 or ErbB2 receptors. However, we could not clearly decipher a role of IRSs in ErbB2 induced tumorigenesis. We expanded our research to the IGF-IR receptor for which ...

B. Litzenburger

2010-01-01

355

Role of IRS1 and IRS2 in Modulating ErbB-induced Tumorigenesis.  

National Technical Information Service (NTIS)

Previous studies suggested that the adapter proteins IRS1 and IRS2 may interact with ErbB1 or ErbB2 receptors. However, I found that overexpression of IRS2 didn't affect ErbB2-induced tumorigenesis or metastasis. Supporting this, I failed to find an assoc...

B. Litzenburger

2010-01-01

356

Atmospheric Entry Experiments at IRS  

NASA Astrophysics Data System (ADS)

Entering the atmosphere of celestial bodies, spacecrafts encounter gases at velocities of several km/s, thereby being subjected to great heat loads. The thermal protection systems and the environment (plasma) have to be investigated by means of computational and ground facility based simulations. For more than a decade, plasma wind tunnels at IRS have been used for the investigation of TPS materials. Nevertheless, ground tests and computer simulations cannot re- place space flights completely. Particularly, entry mission phases encounter challenging problems, such as hypersonic aerothermodynamics. Concerning the TPS, radiation-cooled materials used for reuseable spacecrafts and ablator tech- nologies are of importance. Besides the mentioned technologies, there is the goal to manage guidance navigation, con- trol, landing technology and inflatable technologies such as ballutes that aim to keep vehicles in the atmosphere without landing. The requirement to save mass and energy for planned interplanetary missions such as Mars Society Balloon Mission, Mars Sample Return Mission, Mars Express or Venus Sample Return mission led to the need for manoeuvres like aerocapture, aero-breaking and hyperbolic entries. All three are characterized by very high kinetic vehicle energies to be dissipated by the manoeuvre. In this field flight data are rare. The importance of these manoeuvres and the need to increase the knowledge of required TPS designs and behavior during such mission phases point out the need of flight experiments. As result of the experience within the plasma diagnostic tool development and the plasma wind tunnel data base, flight experiments like the PYrometric RE-entry EXperiment PYREX were developed, fully qualified and successfully flown. Flight experiments such as the entry spectrometer RESPECT and PYREX on HOPE-X are in the conceptual phase. To increase knowledge in the scope of atmospheric manoeuvres and entries, data bases have to be created combining both 3-D calculations and obtained flight data. Experience in this field and flight data are rare. But there are data bases in the USA, where public access is often difficult. The data mostly deal with reuseable launch vehi- cle technology which is a concern for the understanding of entry missions to earth and for the aim to reduce payload transportation costs in future. For X-38 about 40 international partners have been collaborating to develop, qualify and fly X-38 which is a technology demonstrator for the Crew Return Vehicle (CRV) of the International Space Station (ISS). About 1000 sensors will be operated to obtain a data base which will be combined with a aerothermodynamic data base (European contribution). Additionally, a lot of instrumentation has been contributed. PYREX-KAT38 meas- uring the temperature distribution in the X-38 nose structure was developed by IRS. The data of the PYREX sensor system contribute to several fields of interest i.e. temperature histories at 5 positons in the nose structure, information about rotational degrees of freedom of the vehicle during entry, statements on the behavior of the TPS material and heat flux distribution. The paper presents experiments that are being developed at IRS. Below summaries of such experi- ments are given: PYREX is a pyrometric entry experiment measuring rear side temperatures of ceramic TPS. It has already been flown twice. The first flight was with the German-Japanese capsule EXPRESS, the second with the capsule MIRKA. PY- REX-KAT38 was delivered to NASA. It is a fully qualified temperature measurement system and will be operated aboard the X-38 vehicle. RESPECT is a spectrometer that will be used to gain spectral data in the flow field around a space vehicle. The main goal is to obtain information about the plasma state in the post shock regime of a vehicle by measuring the spectrally resolved radiation. The obtained database will provide radiation of multiple species for a comparison with computer simulations. PHLUX: Based on experiences with PYREX, a sensor for heat flux measurements is being de

Auweter-Kurtz, M.; Endlich, P.; Herdrich, G.; Kurtz, H.; Laux, T.; Löhle, S.; Nazina, N.; Pidan, S.

2002-01-01

357

Activation of human monocytes by both human ?1H and C3b  

PubMed Central

We tested whether highly purified human ?1H and C3b, two proteins of the alternative pathway of complement activation, could exert an influence on the activity of human monocytes (M?). The activation process of M? was assessed by measurements of the respiratory burst in terms of nitro blue tetrazolium (NBT) reduction and by chemiluminescence (CL) tests. In NBT reduction experiments, we found a tendency for ?1H to increase NBT reduction, while C3b was found to be rather inhibitory. In CL measurements, both ?1H and C3b displayed a stimulatory effect on M?, showing different time- and dose-dependency. For ?1H, the maximum stimulation occurred after 15 min, whereas for C3b after 45 min. Zymosan particles which served as a positive control also showed the highest stimulation after 45 min. In dose—response experiments, ?1H reached a plateau ranging from 30 to 80 ?g/ml. In contrast, using C3b up to 170 ?g/ml, no plateau was reached. M?-depletion and enrichment studies suggested at M? as being responsible for the stimulatory effects found. The differences between NBT reduction and CL could possibly be explained by the measurement of only cell-bound reductive potentials by NBT reduction, while in CL measurements, products of the extracellular space are also assessed. Our results suggest that both human ?1H and C3b are appropriate stimuli for human monocytes.

Schopf, R. E.; Hammann, K. P.; Scheiner, O.; Lemmel, E.-M.; Dierich, M. P.

1982-01-01

358

Synthesis and structure-activity relationships of 3-hydrazono-1H-2-indolinones with antituberculosis activity.  

PubMed

A series of 3-[S-(4-substituted phenacyl)-4-substituted-isothiosemicarbazono]-1H-2-indolinones+ ++ 2a-h and 3-[(3,4-disubstituted-4-thiazolin-2-ylidene)hydrazono]-1H-2- indolinones 3a-f were synthesized. These new hydrazonoindolinone derivatives and 3-(4-substituted-thiosemicarbazono)-1H/1-acetyl-2-indolinones++ + 1a-g 3-[(2-substituted-4-thiazolidinon-2-ylidene)hydrazono]-1H-2- indolinones 4a-o, 3-[(2-substituted-4-carboxy/carbetoxy-5-methyl-4-thiazolin-2 -ylidene) hydrazono]-1H-2-indolinones 5a-e and 3-substituted-hydrazono-1H-2-indolinones 6a-o which had been previously reported were evaluated for antituberculosis activity against Mycobacterium tuberculosis H37Rv. These compounds exhibited varying degrees of inhibition in the in vitro primary screening that was conducted at 12 micrograms/ml against M. tuberculosis H37Rv in BACTEC 12B medium using the BACTEC 460 radiometric system. 2a, 2c, 2f-h, 3c and 3f demonstrating activity in the primary screen were re-tested at lower concentrations against M. tuberculosis H37Rv to determine the actual minimum inhibitory concentration (MIC) in CABTEC 460. The structure-activity relationships of the derivatives were investigated. PMID:9706377

Karah, N; Terzio?lu, N; Gürsoy, A

1998-07-01

359

Measurements of the ^1H(^18F,p)^18F and ^1H(^18F,?)^15O Excitation Functions at the HRIBF  

NASA Astrophysics Data System (ADS)

Knowledge of the astrophysical ^18F(p,?)^15O rate is important for understanding gamma-ray emission from novae and heavy-element production in x-ray bursts. A state with Ex ~= 7.075 MeV in ^19Ne provides an s-wave resonance and, depending on its properties, could dominate the ^18F(p,?)^15O rate. By simultaneously measuring the ^1H(^18F,p)^18F and ^1H(^18F,?)^15O excitation functions with a radioactive ^18F beam at ORNL's Holifield Radioactive Ion Beam Facility, we have resolved discrepancies(Utku et al.), Phys. Rev. C57, 2731 (1998).^,(Coszach et al.), Phys. Lett. B353, 184 (1995).^,(Rehm et al.), Phys. Rev. C52, R460 (1995); 53, 1950 (1996). in the properties of this astrophysically-important state. Our results will be presented.

Bardayan, D. W.; Blackmon, J. C.; Smith, M. S.; Bradfield-Smith, W.; Lewis, R.; Parker, P. D.; Visser, D. W.; Brune, C. R.; Champagne, A. E.; Johnson, B. A.; Kozub, R. L.; Davinson, T.; Shotter, A. C.; Woods, P. J.; Lee, C. S.

2000-10-01

360

Determination of glucan phosphorylation using heteronuclear (1) H,(13) C double and (1) H,(13) C,(31) P triple-resonance NMR spectra.  

PubMed

Phosphorylation and dephosphorylation of starch and glycogen are important for their physicochemical properties and also their physiological functions. It is therefore desirable to reliably determine the phosphorylation sites. Heteronuclear multidimensional NMR-spectroscopy is in principle a straightforward analytical approach even for complex carbohydrate molecules. With heterogeneous samples from natural sources, however, the task becomes more difficult because a full assignment of the resonances of the carbohydrates is impossible to obtain. Here, we show that the combination of heteronuclear (1) H,(13) C and (1) H,(13) C,(31) P techniques and information derived from spectra of a set of reference compounds can lead to an unambiguous determination of the phosphorylation sites even in heterogeneous samples. Copyright © 2013 John Wiley & Sons, Ltd. PMID:23913630

Schmieder, Peter; Nitschke, Felix; Steup, Martin; Mallow, Keven; Specker, Edgar

2013-08-04

361

Magnesium Silicate Dissolution Investigated by 29Si MAS, 1H-29Si CP MAS, 25Mg QCPMG, and 1H-25Mg CP QCPMG NMR  

SciTech Connect

Olivine has been the subject of frequent investigation in the earth sciences because of its simple structure and rapid dissolution kinetics. Several studies have observed a preferential release of magnesium with respect to silica during weathering under acidic conditions, which has been correlated to the formation of a silicon rich leached layer. While leached layer formation has been inferred through the changing solution chemistry, a thorough spectroscopic investigation of olivine reacted under acidic conditions has not been conducted. In particular, the fate of magnesium in the system is not understood and spectroscopic interrogations through nuclear magnetic resonance can elucidate the changing magnesium coordination and bonding environment. In this study, we combine analysis of the changing solution chemistry with advanced spectroscopic techniques (29Si MAS, 1H-29Si CP MAS, 25Mg QCPMG, and 1H-25Mg 2 CP QCPMG NMR) to probe leached layer formation and possible secondary phase precipitation during the dissolution of forsterite at 150 oC.

Davis, Michael C.; Brouwer, William J.; Wesolowski, David J.; Anovitz, Lawrence M.; Lipton, Andrew S.; Mueller, Karl T.

2009-08-01

362

Bis{?-1-[(2-ethyl-1H-imidazol-1-yl)meth-yl]-1H-benzotriazole}bis-(iodido-cadmium)  

PubMed Central

The dinuclear title complex, [Cd2I4(C12H13N5)2], lies on a crystallographic center of inversion. The CdII atom is four-coordinated by two N atoms from two 1-[(2-ethyl-1H-imidazol-1-yl)meth­yl]-1H-benzotriazole (bmei) ligands and two terminal I atoms in a distorted tetra­hedral coordination environment. The CdII atoms are connected to each other by two bridging bmei ligands. The benzotriazole rings in adjacent mol­ecules are almost parallel, with an average inter­planar distance of 3.3400?(2)?Å and a centroid–centroid distance of 4.852?(2)?Å.

Wang, Xia; Niu, Jun-long

2011-01-01

363

Synthesis, structures, simulated IR spectra and two-dimensional infrared correlation spectroscopy of two nitrogen-heterocyclic ?-octamolybdate supported compounds  

NASA Astrophysics Data System (ADS)

Two metal-organic ?-octamolybdate supported compounds containing nitrogen-heterocyclic ligands, [Co(dpq)2 H2O]2[?-Mo8O26] 0.5H2O 1, (H3biim)4[?-Mo8O26] 2 (dpq = 1,10-phenanthroline-5,6-dione; H2bimm = 2,2?-biimidazole), have been hydrothermally synthesized and characterized by X-ray crystal structural analysis, elemental analysis, IR spectrum, UV-VIS DRIS, 2D-IR COS (two-dimensional infrared correlation spectroscopy), PXRD, TG analysis, simulated IR spectrum and theoretical calculations from HOMO-LUMO. X-ray crystal structural analyses reveal that compound 1 has the 1-D supramolecular structure, which is formed via hydrogen bonds between water molecules coordinated to Co2+. In compound 2, the 2-D supramolecular structure is built by aromatic-aromatic stacking interactions and H-bonds between ligands. Simulated IR spectra gained by quantum calculation are used for structure discussion, which is the first time that simulated IR results are used to reveal the relationship between bond vibrations of ?-octamolybdate compounds and their related IR peak responses. Additionally, by using 2D-IR COS, structural properties like thermal and magnetic sensitivities have also been analyzed.

Chen, Xiang-Yi; Chen, Yi-Ping; Chai, Feng; Sun, Yan-Qiong; Huang, Bi-Hua

2013-03-01

364

Airborne passive FT-IR spectrometry  

Microsoft Academic Search

Rapid airborne identification and quantification of vapor hazards is an environmentally important capability for a variety of open-air scenarios. This study demonstrates the use of a commercially available passive Fourier transform IR (FT-IR) spectrometer to detect, identify, and quantify ammonia and ethanol vapor signatures depending on the appropriate signal processing strategy. The signal- processing strategy removes the need for a

Robert T. Kroutil; Roger J. Combs; Robert B. Knapp; Gary W. Small

2002-01-01

365

IRS proteins and beta-cell function.  

PubMed

Insulin receptor substrate (IRS) proteins mediate a variety of the metabolic and growth-promoting actions of insulin and IGF-1. After phosphorylation by activated receptors, these intracellular signaling molecules recruit various downstream effector pathways including phosphatidylinositol 3-kinase and Grb2. Ablation of the IRS-2 gene produces a diabetic phenotype; mice lacking IRS-2 display peripheral insulin resistance and beta-cell dysfunction characterized by a 50% reduction in beta-cell mass. In contrast, deletion of IRS-1 retards somatic growth and enhances beta-cell mass. IRS1-/- mice are 50% smaller than controls but have a twofold increase in pancreatic beta-cell mass. Thus, observations from these recently developed animal models implicate the IRS signaling systems in the response of classical insulin target tissues, and they suggest a critical role for these proteins in the regulation of beta-cell function. In humans, type 2 diabetes generally occurs when insulin-secretory reserves fail to compensate for peripheral insulin resistance. Study and identification of the signals downstream of IRS proteins in beta-cells may provide unique insights into the compensatory mechanisms by which these cells respond to insulin resistance. Therefore, the intent of this review is to summarize recent observations regarding the regulation of beta-cell function by members of the IRS protein family. PMID:11272176

Burks, D J; White, M F

2001-02-01

366

Concept based retrieval in classical IR systems  

Microsoft Academic Search

This paper describes some aspects of a project with the aim of developing a user-friendly interface to a classical Information Retrieval (IR) System in order to improve the effectiveness of retrieval. The character by character approach to IR has been abandoned in favor of an approach based on the meaning of both the queries and the texts containing the information

H. P. Giger

1988-01-01

367

IGF-IR Signaling in Breast Cancer.  

National Technical Information Service (NTIS)

Clinical and experimental evidence suggest that the insulin-like growth factor receptor (IGF-IR) is involved in breast cancer etiology. For instance, IGF-IR is overexpressed in breast tumors (relative to normal breast epithelium) and high levels of IGF-I ...

E. Surmacz

1998-01-01

368

Cooled IR detectors calibration analysis and optimization  

Microsoft Academic Search

As far as high performance IR detector are concerned, MWIR cooled 2D arrays are more and more used for high quality systems which need the uniformity and quality of the response in order to offer a good non uniformity corrections (NUC) and a stable IR detector calibrations. The aim of this paper is to demonstrate the state of the art

Patrice Fillon; Agnes Combette; Philippe Tribolet

2005-01-01

369

Nonpeptide angiotensin II receptor antagonists. 2. Design, synthesis, and structure-activity relationships of 2-alkyl-4-(1H-pyrrol-1-yl)-1H-imidazole derivatives: profile of 2-propyl-1-[[2'-(1H-tetrazol-5-yl)-[1,1' -biphenyl]-4-yl]-methyl]-4-[2-(trifluoroacetyl)-1H-pyrrol-1-yl]-1H- imidazole-5-carboxylic acid (CI-996).  

PubMed

A novel series of nonpeptide angiotensin II (AII) receptor antagonists containing a 1H-pyrrol-1-yl moiety at the 4-position of the imidazole have been developed. The pyrrole group occupies the same lipophilic pocket at the receptor as the chloro group in DuP 753 (68) and EXP 3174 (69) and the pentafluoro group in DuP 532 (70), respectively. The impetus for its selection came from bioisosteric considerations based on hydrophobic and electronic substituent constants. An extensive study of the structure-activity relationships revealed several highly potent AII receptor antagonists. An acyl substitution at the 2-position of the pyrrole ring improved activity, most notably in the in vivo rat model. In addition, the 2-substituted pyrrole compounds improved chemical stability toward extremely facile decarboxylation reaction associated with unsubstituted pyrrole analogues, thus facilitating development of these agents. The IC50's of 18, 20, and 42 (< 1 nM) were better than the reference compounds 69 and 70, respectively. These compounds were selective AII antagonists that compete at the AT1 receptor and showed no affinity at the AT2 receptor at concentrations up to 10 microM. Upon intravenous administration in a normotensive rat model, compound 18 inhibited the AII-induced responses with ED50 of 6 micrograms/kg per min. In a renal hypertensive rat model, the antihypertensive potency of compound 18, at a dose of 10 mg/kg, was very similar to those 68 and 69, respectively. Compound 18 demonstrated a dose-related (3-30 mg/kg) decrease in blood pressure that was sustained for greater than 24 h. On the basis of its profile, compound 18, designated as CI-996, has been selected for in-depth studies. The design, synthesis, in vitro, and in vivo structure-activity relationships are described. PMID:8360871

Sircar, I; Hodges, J C; Quin, J; Bunker, A M; Winters, R T; Edmunds, J J; Kostlan, C R; Connolly, C; Kesten, S J; Hamby, J M

1993-08-01

370

Elevated Glutamatergic Compounds in Pregenual Anterior Cingulate in Pediatric Autism Spectrum Disorder Demonstrated by 1H MRS and 1H MRSI  

Microsoft Academic Search

Recent research in autism spectrum disorder (ASD) has aroused interest in anterior cingulate cortex and in the neurometabolite glutamate. We report two studies of pregenual anterior cingulate cortex (pACC) in pediatric ASD. First, we acquired in vivo single-voxel proton magnetic resonance spectroscopy (1H MRS) in 8 children with ASD and 10 typically developing controls who were well matched for age,

Anthony Bejjani; Joseph ONeill; John A. Kim; Andrew J. Frew; Victor W. Yee; Ronald Ly; Christina Kitchen; Noriko Salamon; James T. McCracken; Arthur W. Toga; Jeffry R. Alger; Jennifer G. Levitt

2012-01-01

371

1-Ethyl-2-phenyl-3-[2-(tri-methyl-sil-yl)ethyn-yl]-1H-indole  

PubMed Central

The title compound, C21H23NSi, was synthesized by Sonogashira-type reaction of 1-ethyl-3-iodo-2-phenyl-1H-indole with tri­methyl­silyl­acetyl­ene. The indole ring system is nearly planar [maximum atomic deviation = 0.0244?(15)?Å] and is oriented at a dihedral angle of 51.48?(4)° with respect to the phenyl ring. The supramolecular aggregation is completed by weak C—H?? inter­actions of the methylene and phenyl groups with the benzene and pyrrole rings of the indole ring system. The methyl groups of the tri­methyl­silyl unit are equally disordered over two sets of sites.

Baglai, Iaroslav; Maraval, Valerie; Duhayon, Carine; Chauvin, Remi

2013-01-01

372

1-Ethyl-2-phenyl-3-[2-(tri-methyl-sil-yl)ethyn-yl]-1H-indole.  

PubMed

The title compound, C21H23NSi, was synthesized by Sonogashira-type reaction of 1-ethyl-3-iodo-2-phenyl-1H-indole with tri-methyl-silyl-acetyl-ene. The indole ring system is nearly planar [maximum atomic deviation = 0.0244?(15)?Å] and is oriented at a dihedral angle of 51.48?(4)° with respect to the phenyl ring. The supramolecular aggregation is completed by weak C-H?? inter-actions of the methylene and phenyl groups with the benzene and pyrrole rings of the indole ring system. The methyl groups of the tri-methyl-silyl unit are equally disordered over two sets of sites. PMID:23795091

Baglai, Iaroslav; Maraval, Valérie; Duhayon, Carine; Chauvin, Remi

2013-05-18

373

Heterohelicenes with embedded P-chiral 1H-phosphindole or dibenzophosphole units: diastereoselective photochemical synthesis and structural characterization.  

PubMed

The oxidative photocyclization reactions of olefins that contain 1H-phosphindole or dibenzophosphole substituents have been applied to the synthesis of P/N-bi-heterosubstituted dimeric helicenes, as well as of new [6]- and [8]phosphahelicenes. In these photocyclization processes, the configuration of the stereogenic phosphorus center dictates the sense of helical chirality. Thus, by starting from enantiomerically pure P-menthylphosphole-oxide units, this method affords enantiopure helical compounds. The helical phosphine oxides were characterized by X-ray diffraction. After reduction of the phosphine-oxides, the corresponding helical phosphines have been used as ligands in transition-metal complexes. The X-ray crystal structure of a gold chloride complex of a [6]helicene is reported. PMID:23766244

Yavari, Keihann; Retailleau, Pascal; Voituriez, Arnaud; Marinetti, Angela

2013-06-13

374

Pseudospin doublet aligned structure in doubly odd {sup 186}Ir  

SciTech Connect

{sup 186}Ir has been restudied through the {sup 180}Hf({sup 11}B,5n) reaction at 65 MeV using in-beam {gamma}-ray and conversion-electron spectroscopy. The unfavored component of the doubly decoupled band was established and shown to be consistent with a description in terms of the {pi}h{sub 9/2}{circle_times}{nu}[{number_sign}411{number_sign}{number_sign}&dbigwig;1/2,3/2] structure, i.e., the coupling of an aligned proton and a neutron pseudospin doublet. {copyright} {ital 1997} {ital The American Physical Society}

Cardona, M.A.; Debray, M.E.; Garcia Bermudez, G.; Hojman, D.; Kreiner, A.J.; Somacal, H.; Burlon, A.; Davidson, J.; Davidson, M.; Levinton, G.; Ozafran, M.; Vazquez, M.; Napoli, D.R.; Rico, J.; Bazzacco, D.; Burch, R.; De Acuna, D.; Lenzi, S.M.; Medina, N.; Rossi Alvarez, C.; Blasi, N.; Lo Bianco, G.; de Boer, J.; Frischke, D.; Maier, H.J. [Departamento de Fisica, Comision Nacional de Energia Atomica, 1429 Buenos Aires (Argentina)

1997-01-01

375

VIS-IR transmitting windows  

NASA Astrophysics Data System (ADS)

The U.S. Naval Research Laboratory (NRL) has developed two unique materials with excellent properties for various military and commercial applications in the UV-Vis-IR wavelength range. These materials are: an amorphous Barium Gallo-Germanate (BGG) glass and a polycrystalline Magnesium Aluminate Spinel. The BGG glass is made using traditional glass melting techniques, and was developed as a low cost alternative to the currently used window materials. Large prototype windows have been fabricated for a Navy reconnaissance program. BGG windows have been successfully tested for environmental ruggedness (MIL-F-48616) and rain erosion durability up to 300 mph. BGG glass is currently under development and evaluation for High Energy Laser (HEL) applications. A new process has been developed to sinter spinel to clear transparency with very high yields. This process has been used to make various sizes and shapes (flats and domes) and is readily scalable to industrial sizes to produce large windows & domes for various applications. NRL has also developed modified BGG glasses, which are compatible with Spinel and ALON substrates for bonding.

Bayya, S. S.; Chin, G. D.; Villalobos, G.; Sanghera, J. S.; Aggarwal, I. D.

2005-05-01

376

Kinetics, stoichiometry, morphology, and current drive capabilities of Ir-based silicides  

SciTech Connect

A detailed study of the formation of iridium silicide obtained by ultrahigh vacuum annealing and atmospheric rapid thermal processing is proposed using x-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and electrical characterizations. Using XPS analysis, the stoichiometry of each silicide phase (IrSi, IrSi{sub 1.6}) is identified. A model based on the variation of the measured intensity of the Ir 4f spectra is used to obtain the kinetic coefficients of reaction of Ir silicidation (E{sub A}=2.48 eV, D{sub 0}=9 cm{sup 2}/s). TEM cross sections indicate that the roughness of the silicide/silicon interface increases with temperature. Lastly, electrical characteristics are used to identify the optimum annealing temperature to obtain an iridium silicide contact with the lowest Schottky barrier height to holes.

Larrieu, G.; Dubois, E.; Wallart, X.; Katcki, J. [Institut d'Electronique de Microelectronique et de Nanotechnologie, IEMN/ISEN UMR CNRS 8520, Avenue Poincare, Cite Scientifique, 59652 Villeneuve d'Ascq Cedex (France); Institute of Electron Technology, Al. Lotnikow 32/46, 02-668 Warsaw (Poland)

2007-11-01

377

Interaction of Na atoms with CsCl molecules on the surface of a graphite monolayer on Ir(III)  

SciTech Connect

The authors have investigated the reaction CsCl + Na ..-->.. NaCl + Cs on the passive surface of a graphite monolayer on Ir(III) under steady-state conditions. The authors judged the reaction from the current of Cs/sup +/ ions formed upon surface ionization of the reaction products. The dependences of the reaction efficiency on the incident particle fluxes and on the surface temperature are considered within the model of the CsClNa complex.

Zandberg, E.Ya.; Nasrullaev, N.M.; Rut'kov, E.V.; Tontegode, A.Ya.

1987-04-01

378

Alzheimer Disease: Postmortem Neuropathologic Correlates of Antemortem 1H MR Spectroscopy Metabolite Measurements  

PubMed Central

Purpose To determine the neuropathologic correlates of antemortem hydrogen 1 (1H) magnetic resonance (MR) spectroscopy metabolite measurements in subjects with Alzheimer disease (AD)-type pathology. Materials and Methods This study was approved by the institutional review board and was compliant with HIPAA regulations. Informed consent was obtained from each subject. The authors identified 54 subjects who underwent antemortem 1H MR spectroscopy and were clinically healthy or had AD-type pathology with low to high likelihood of AD according to National Institute on Aging–Reagan neuropathologic criteria at autopsy. They investigated the associations between 1H MR spectroscopy metabolite measurements and Braak neurofibrillary tangle stage (Braak stage), neuritic plaque score, and AD likelihood, with adjustments for subject age, subject sex, and time between 1H MR spectroscopy and death. Results Decreases in N-acetylaspartate–to-creatine ratio, an index of neuronal integrity, and increases in myo-inositol–to-creatine ratio were associated with higher Braak stage, higher neuritic plaque score, and greater likelihood of AD. The N-acetylaspartate–to–myo-inositol ratio proved to be the strongest predictor of the pathologic likelihood of AD. The strongest association observed was that between N-acetylaspartate–to–myo-inositol ratio and Braak stage (RN2 = 0.47, P < .001). Conclusion Antemortem 1H MR spectroscopy metabolite changes correlated with AD-type pathology seen at autopsy. The study findings validated 1H MR spectroscopy metabolite measurements against the neuropathologic criteria for AD, and when combined with prior longitudinal 1H MR spectroscopy findings, indicate that these measurements could be used as biomarkers for disease progression in clinical trials.

Kantarci, Kejal; Knopman, David S.; Dickson, Dennis W.; Parisi, Joseph E.; Whitwell, Jennifer L.; Weigand, Stephen D.; Josephs, Keith A.; Boeve, Bradley F.; Petersen, Ronald C.; Jack, Clifford R.

2009-01-01

379

Electrochemical and IR spectroelectrochemical studies of the electrocatalytic reduction of carbon dioxide by [Ir{sub 2}(dimen){sub 4}]{sup 2+} (dimen = 1,8-diisocyanomenthane)  

SciTech Connect

The electrocatalytic reactions of carbon dioxide that are catalyzed by [Ir{sub 2}(dimen){sub 4}]{sup 2+} (dimen = 1,8-diisocyanomenthane) were studied with cyclic voltammetry and infrared spectroelectrochemistry. The hexafluorophosphate (PF{sub 6}{sup -}) salt and the tetraphenylborate (B(C{sub 6}H{sub 5}){sub 4}{sup -}) salt are electrocatalysts for carbon dioxide reduction. Infrared spectroelectrochemistry allowed the identification of the carbon dioxide reduction products and provided information about the mechanism(s) of the reduction. Biocarbonate and formate were identified as the electrocatalytic carbon dioxide reaction products by comparing the infrared bands observed by spectroelectrochemistry with authentic samples of tetrabutylammonium oxalate, and tetrabutylammonium bicarbonate. Formate arises from a net two-electron reduction of carbon dioxide that produces free formate and a formate complex of [Ir{sub 2}(dimen){sub 4}]{sup 2+}. Bicarbonate results from the reaction of hydroxide (produced when residual water is reduced to hydrogen) with carbon dioxide.

Cheng, S.C.; Blaine, C.A.; Hill, M.G.; Mann, K.R. [Univ. of Minnesota, Minneapolis, MN (United States)

1996-12-18

380

Diazirine-modified gold nanoparticle: template for efficient photoinduced interfacial carbene insertion reactions.  

PubMed

Photolysis of a 3-aryl-3-(trifluoromethyl)diazirine-modified monolayer-protected gold nanoparticles (2-C(12)MPNs), with a core size of 1.8 ± 0.3 nm, in the presence of model carbene trapping reagents leads to efficient, essentially quantitative, modification of the interface via carbene insertion reactions. The utility of carbene insertion reactions as a general approach for the modification of Au-MPNs to provide a breadth of new structures available was demonstrated using acetic acid, methanol, benzyl alcohol, phenol, benzylamine, methyl acrylate, and styrene (10a-g, respectively) as electrophilic carbene trapping agents to form the corresponding modified 3a-g-C(12)MPNs. The 1.8 ± 0.3 nm gold nanoparticles bearing a diazirine group (2-C(12)MPNs) were synthesized using the ligand exchange reaction with the requisite 3-aryl-3-(trifluoromethyl)diazirinealkylthiol. The 2-C(12)MPNs and the resulting products of the reaction on the MPN (3a-g-C(12)MPN) were fully characterized by IR, (1)H NMR, and (19)F NMR spectroscopy and, when applicable, transmission electron microscopy (TEM). Verification for the 3a-g-C(12)MPNs was accomplished by comparison of the spectral data to those of obtained for the photoreactions of 3-(3-methoxyphenyl)-3-(trifluoromethyl)-3H-diazirine as a model with 10a-g. PMID:20735050

Ismaili, Hossein; Lee, Soo; Workentin, Mark S

2010-09-21

381

2H and 1H NMR study on hydrogen isotope effects in silicate glasses  

NASA Astrophysics Data System (ADS)

A series of experiments were conducted to investigate hydrogen isotope effects between the two forms of water dissolved in silicate glasses, i.e. as silanol groups (silica bound hydroxyl) and dissolved water molecules. The starting material was a dry synthetic glass (Na2O?4SiO2) with 6 wt% water of varying 2H/1H ratios equilibrated at 1400°C and 1.5 GPa and quenched to a glass at a rate of ~100°C/s. Experimental duration ranged from 3 hrs to 2 days. Single-pulse 2H and 1H NMR experiments were performed to characterize the speciation of each isotope in the glass, which allows quantitative estimation of isotope fractionation factor (?) between H in silanol group and H in dissolved water molecules. From the 1H NMR data <25% of total 1H is present in silanol groups, whereas 2H NMR reveals that more than 80% of the total 2H is in silanol groups. As 2H2O proportion of the starting water mixture increases from 10, to 50, 90, and 100%, the partitioning of 2H between silanol groups and water molecules remains constant near 4:1, whereas 1H increasingly proportionates into molecular water. Consequently, the measured fractionation factor (? = [2H/1H]silanol/[2H/1H]molecule) increases from 14.6 (water D:H=1:9) to 24.5 (water D:H=9:1). Prolonged experimental duration does not affect the value of apparent fractionation factors, suggesting attainment of isotopic equilibrium. The observed hydrogen isotope fractionation is most easily explained as molar volume isotope effects (MVIE). These effects are generally understood in terms of isotope effects on bond vibrational amplitudes, leading to distinct molar volume of different isotopologues (Jancso et al., 1993). It has been shown, for example, that O-2H bonds in hydrous minerals have greater compressibility than O-1H bonds (Horita et al., 2010), i.e., normal MVIE; whereas molecular water at high-pressures (>20 MPa) shows V(2H2O) > V(1H2O), giving rise to inverse MVIE (Horita et al., 2002; Polyakov et al., 2006). The combined effects would act to accommodate preferentially 2H in silanol groups relative to water molecules in the quenched silicate melts, which is consistent with our observation. However, our fractionation factors are substantially higher than previously reported from experimental or theoretical studies between bulk silicate glasses/minerals and water vapor. This difference may be due to the fact that our study focuses on dissolved water in the melt at water contents below the saturation limit.

Wang, Y.; Cody, S. X.; Cody, G. D.; Mysen, B. O.

2011-12-01

382

PREMIER's imaging IR limb sounder  

NASA Astrophysics Data System (ADS)

The Imaging IR Limb Sounder (IRLS) is one of the two instruments planned on board of the candidate Earth Explorer Core Mission PREMIER. PREMIER stands for PRocess Exploration through Measurements of Infrared and Millimetrewave Emitted Radiation and is presently under feasibility study by ESA. Emerging from recent enhanced detector and processing technologies IRLS shall, next to a millimetre-wave limb sounder, explore the benefits of three-dimensional limb sounding with embedded cloud imaging capability. Such 3d imaging technology is expected to open a new era of limb sounding that will allow detailed studies of the link between atmospheric composition and climate, since it will map simultaneously fields of temperature and many trace gases in the mid/upper troposphere and stratosphere across a large vertical and horizontal field of view and with relatively high vertical and horizontal resolution. PREMIER shall fly in tandem formation looking backwards to METOP's swath and thereby explore the benefit of 3-dimensional information for meteorological/environmental analyses and climate forcing investigations. As currently planned and if implemented, IRLS will cover a total horizontal field of about 360 km and observe the limb at altitudes between 4 and 52 km. The vertical spatial sampling distance (SSD) will be well below 1 km. It will be run in two different exclusive modes to address scientific questions about atmospheric dynamics and chemistry at spectral samplings of ~1.2 cm-1 and ~0.2 cm-1, respectively. In such configuration IRLS will be composed of an imaging array with about 1800 macro pixels or sub-samples, thereby allowing cloud imaging and rejection at sufficient spatial resolution. We will present an overview of the instrument requirements as derived from the scientific requirements, the present status of the mission, and we will give an overview of the currently identified technology needs and instrument predevelopments.

Kraft, Stefan; Caron, Jerome; Bézy, Jean-Loup; Meynart, Roland; Langen, Jörg; Carnicero Dominguez, Bernardo; Bensi, Paolo; Silvestrin, Pierluigi

2011-10-01

383

Synthesis and characterization of nido-[1,1,2,2-(CO){sub 4}-1,2-(PPh{sub 3}){sub 2}-1,2-FeIrB{sub 2}H{sub 5}]: A heterobimetallaborane analogue of nido-[B{sub 4}H{sub 7}]{sup -}  

SciTech Connect

The synthesis and characterization of nido-[1,1,2,2-(CO){sub 4}-1,2-(PPh{sub 3}){sub 2}-1,2-FeIrB{sub 2}H{sub 5}] (1) is reported. 1 is formed in low yield as a degradation product from the reaction between [({mu}-Fe(CO){sub 4})B{sub 6}H{sub 9}]{sup -} and trans-Ir(CO)Cl(PPh{sub 3}){sub 2} in THF and is characterized from NMR, IR, and analytical data and by a single-crystal X-ray diffraction study. 1 crystallizes in the monoclinic space group P2/n with a = 12.8622(12), b = 14.3313(12), c = 23.579(3) {angstrom}, {beta} = 97.12(2){degrees}, Z = 4, V = 4257.0(8) {angstrom}{sup 3}, R = 4.83%, and wR{sub 2}(F{sup 2}) = 12.43%. The heterobimetallaborane structure may be viewed as a derivative of the binary boron hydride nido-[B{sub 4}H{sub 7}]{sup -} and is related to the known homobimetallatetraborane analogues [Fe{sub 2}(CO){sub 6}B{sub 2}H{sub 6}] and [Co{sub 2}(CO){sub 6}B{sub 2}H{sub 4}]. 1 exhibits proton fluxionality in its {sup 1}H NMR spectrum, which is related to that found in the latter two compounds.

Bould, J.; Rath, N.P.; Barton, L. [Univ. of Missouri, St. Louis, MO (United States)

1996-01-03

384

Hematocrit and oxygenation dependence of blood (1) H(2) O T(1) at 7 tesla.  

PubMed

Knowledge of blood (1) H(2) O T(1) is critical for perfusion-based quantification experiments such as arterial spin labeling and cerebral blood volume-weighted MRI using vascular space occupancy. The dependence of blood (1) H(2) O T(1) on hematocrit fraction (Hct) and oxygen saturation fraction (Y) was determined at 7 T using in vitro bovine blood in a circulating system under physiological conditions. Blood (1) H(2) O R(1) values for different conditions could be readily fitted using a two-compartment (erythrocyte and plasma) model, which are described by a monoexponential longitudinal relaxation rate constant dependence. It was found that T(1) = 2171 ± 39 ms for Y = 1 (arterial blood) and 2010 ± 41 ms for Y = 0.6 (venous blood), for a typical Hct of 0.42. The blood (1) H(2) O T(1) values in the normal physiological range (Hct from 0.35 to 0.45, and Y from 0.6 to 1.0) were determined to range from 1900 to 2300 ms. The influence of oxygen partial pressure (pO(2) ) and the effect of plasma osmolality for different anticoagulants were also investigated. It is discussed why blood (1) H(2) O T(1) values measured in vivo for human blood may be about 10-20% larger than found in vitro for bovine blood at the same field strength. Magn Reson Med, 2012. © 2012 Wiley Periodicals, Inc. PMID:23169066

Grgac, Ksenija; van Zijl, Peter C M; Qin, Qin

2012-11-20

385

Dipolar filtered 1H-13C heteronuclear correlation spectroscopy for resonance assignment of proteins.  

PubMed

Resonance assignment is necessary for the comprehensive structure determination of insoluble proteins by solid-state NMR spectroscopy. While various 2D and 3D correlation techniques involving 13C and 15N spins have been developed for this purpose, H chemical shift has not been exploited sufficiently. We demonstrate the combination of the regular 1H-13C heteronuclear correlation (HETCOR) experiment and a dipolar filtered HETCOR technique to obtain better resolved 1H chemical shift spectra. The dipolar filtered experiment, MELODI-HETCOR. simplifies the 1H spectra by suppressing the directly bonded C-H correlation peaks and retaining only the medium- and long-range cross peaks. We apply this MELODI-HETCOR technique to several amino acids and proteins with various isotopic labeling patterns. The enhanced 1H chemical shift resolution allows the assignment of overlapping H alpha and H beta resonances in Ser, identifies the 1H chemical shift differences between neutral and cationic imidazole rings of His, and permits the assignment of residues with side chain nitrogen atoms in ubiquitin. The potential utility of this dipolar filtered HETCOR technique to resonance assignment of extensively labeled proteins is discussed. PMID:11519749

Yao, X L; Hong, M

2001-07-01

386

Gene content and virtual gene order of barley chromosome 1H.  

PubMed

Chromosome 1H (approximately 622 Mb) of barley (Hordeum vulgare) was isolated by flow sorting and shotgun sequenced by GSFLX pyrosequencing to 1.3-fold coverage. Fluorescence in situ hybridization and stringent sequence comparison against genetically mapped barley genes revealed 95% purity of the sorted chromosome 1H fraction. Sequence comparison against the reference genomes of rice (Oryza sativa) and sorghum (Sorghum bicolor) and against wheat (Triticum aestivum) and barley expressed sequence tag datasets led to the estimation of 4,600 to 5,800 genes on chromosome 1H, and 38,000 to 48,000 genes in the whole barley genome. Conserved gene content between chromosome 1H and known syntenic regions of rice chromosomes 5 and 10, and of sorghum chromosomes 1 and 9 was detected on a per gene resolution. Informed by the syntenic relationships between the two reference genomes, genic barley sequence reads were integrated and ordered to deduce a virtual gene map of barley chromosome 1H. We demonstrate that synteny-based analysis of low-pass shotgun sequenced flow-sorted Triticeae chromosomes can deliver linearly ordered high-resolution gene inventories of individual chromosomes, which complement extensive Triticeae expressed sequence tag datasets. Thus, integration of genomic, transcriptomic, and synteny-derived information represents a major step toward developing reference sequences of chromosomes and complete genomes of the most important plant tribe for mankind. PMID:19692534

Mayer, Klaus F X; Taudien, Stefan; Martis, Mihaela; Simková, Hana; Suchánková, Pavla; Gundlach, Heidrun; Wicker, Thomas; Petzold, Andreas; Felder, Marius; Steuernagel, Burkhard; Scholz, Uwe; Graner, Andreas; Platzer, Matthias; Dolezel, Jaroslav; Stein, Nils

2009-08-19

387

A new europium(III) complex containing a neutral ligand of 2-(pyridin-2-yl)-1H-benzo[d]imidazole: thermal, electrochemical, luminescent properties.  

PubMed

A new europium(III) complex i.e. Eu(ECTFBD)3PBI was synthesized, where ECTFBD and PBI are 4-(9-ethyl-9H-carbazol-3-yl)-1,1,1-trifluoro-4-oxobutan-2-olate anion and 2-(pyridin-2-yl)-1H-benzo[d]imidazole, respectively. Its IR, UV-Vis spectra, electrochemical, thermal properties as well as photoluminescent performances in solid state and in CH2Cl2 were investigated. Eu(ECTFBD)3PBI exhibited strong red emission without any emission from ECTFBD and PBI in solid state, but with a very weak emission from ECTFBD in CH2Cl2. We explored this difference of the luminesecences of Eu(ECTFBD)3PBI in solid state and in CH2Cl2 based on the excited triplet energy levels of ECTFBD and PBI. PMID:23416914

Liu, Jian; Li, Shuigen; Liao, Weibing; Chen, Yong

2013-01-23

388

Synthesis, spectroscopic and structural evaluation of ethyl 2-cyano-3-{5-[(4-nitro-benzoyl)-hydrazonomethyl]-1H-pyrrol-2-yl}-acrylate using experimental and theoretical approaches  

NASA Astrophysics Data System (ADS)

A new C-vinylpyrrole containing aroylhydrazone, ethyl 2-cyano-3-{5-[(4-nitro-benzoyl)-hydrazonomethyl]-1H-pyrrol-2-yl}-acrylate (ECNBHPA) derived from ethyl 2-cyano-3-(5-formyl-1H-pyrrol-2-yl)-acrylate and 4-nitro-benzohydrazide has been characterized by various spectroscopic techniques (1H NMR, 13C NMR, Mass, UV–Visible, Emission, FT-IR). TD-DFT has been used to calculate the various electronic excitations and their nature within molecule. The emission spectra of ECNBHPA show photoluminescent behavior of title molecule. Natural bond orbital (NBO) analysis has been carried out to explore the various conjugative/hyperconjugative interactions within molecule and their second order stabilization energy (E(2)). A combined experimental and theoretical vibrational analysis designates presence of the classical hydrogen bonding N1H29⋯N9 between pyrrole NH as proton donor and N atom of cyanide as proton acceptor. To determine the strength and nature of hydrogen bonding, topological parameters at bond critical points (BCP) have been analyzed by 'Quantum theory of atoms in molecules' (QTAIM) in detail. The result of hydrogen bonding is obvious in 1H NMR, FT-IR and ESP map as down field chemical shift, vibrational red shift and absence of blue colur relative to pyrrole NH proton, respectively. Global electrophilicity index (? = 6.573 eV) shows that title molecule behaves as a strong electrophile. The local reactivity descriptors analyses such as Fukui functions (fk+,fk-), local softnesses (sk+,sk-) and electrophilicity indices (?k+,?k-) have been performed to determine the reactive sites within molecule. The first hyperpolarizability (?0) of ECNBHPA has been computed to evaluate the non-linear optical (NLO) response of the investigated molecule.

Singh, R. N.; Kumar, Amit; Rawat, Poonam; Srivastsva, Anchal

2013-10-01

389

Synthesis, crystal structures and theoretical calculations of new 1-[2-(5-chloro-2-benzoxazolinone-3-yl)acetyl]-3,5-diphenyl-4,5-dihydro-(1H)-pyrazoles  

NASA Astrophysics Data System (ADS)

1-[2-(5-Chloro-2-benzoxazolinone-3-yl)acetyl]-3-phenyl-5-(3-methoxyphenyl)-4,5-dihydro-(1H)-pyrazole (5a), 1-[2-(5-chloro-2-benzoxazolinone-3-yl)acetyl]-3-phenyl-5-(3,4-dimethoxyphenyl)-4,5-dihydro-(1H)-pyrazole (5b) and 1-[2-(5-chloro-2-benzoxazolinone-3-yl)acetyl]-3-(4-methylphenyl)-5-(2,3-dimethoxyphenyl)-4,5-dihydro-(1H)-pyrazole (5c) were synthesized. The crystal and molecular structures of the compounds 5a, 5b and 5c were determined by elemental analyses, IR, 1H NMR, ESI-MS and single-crystal X-ray diffraction. DFT method with 6-31G(d,p) basis set was used to calculate the optimized geometrical parameters, vibrational frequencies and chemical shift values. The calculated vibrational frequencies and chemical shift values were compared with experimental IR and 1H NMR values. The results represented that there was a good agreement between experimental and calculated values of the compounds 5a-5c. In addition, DFT calculations of the compounds, molecular electrostatic potentials (MEPs) and frontier molecular orbitals were performed at B3LYP/6-31G(d,p) level of theory. Furthermore, compounds were tested against three Gram-positive bacteria: Staphylococcus aureus ATCC 29213 (American Type Culture Collection), methicillin resistant S. aureus (MRSA) ATCC 43300 and Enterococcus faecalis ATCC 29212; two Gram negative bacteria: Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853; and three fungi: Candida albicans ATCC 90028, Candida krusei ATCC 6258 and Candida parapsilosis ATCC 90018. In general, all of the compounds were found to be slightly active against tested microorganisms.

Gök?en, Umut Salgin; Alpaslan, Yelda Bingöl; Kelekçi, Nesrin Gökhan; I?ik, ?amil; Ekizo?lu, Melike

2013-05-01

390

FT-IR and NMR spectroscopic studies of salicylic acid derivatives. I. Gentisamide -- a metabolite of salicylamide.  

PubMed

Gentisamide (GAM, 2,5-dihydroxybenzamide), a minor first-pass metabolite of salicylamide (SAM, 2-hydroxybenzamide), was studied using FT-IR, 1D and 2D homo- and heteronuclear 1H and 13C NMR spectroscopy. GAM was isolated from human urine eight hours after oral administration of SAM. FT-IR, 1H and 13C NMR spectra unequivocally confirmed the chemical structure of GAM through chemical and substituent shifts, coupling constants and connectivities in COSY, NOESY, HETCOR and HBMC spectra. From NOESY spectra of GAM in DMSO-d6, it was concluded that the amide protons are oriented toward the ortho-proton at C-6. Obtained results indicate that the presence of the additional phenol group at C-5 in GAM favours the formation of intramolecular hydrogen bonding of the O...HO type between C2-OH proton and oxygen atom of the amide group. PMID:15610614

Jadrijevi?-Mladar Takac, Milena; Viki? Topi?, Drazen; Govorcinovi?, Tihana

2004-09-01

391

Quantitative measurements of glutathione in yeast cell lysate using 1H NMR.  

PubMed

Methods for quantifying the level of glutathione (GSH) in yeast cell lysate are described using (1)H NMR analysis. For quantification purposes, the (1)H resonances corresponding to the Cys ?CH2 of GSH were identified as having the fewest overlapping spectral interferences from lysate matrix components using GSH spiked yeast lysate samples. Two methods, standard addition based on peak integration and a spectral subtraction approach, were evaluated for quantifying GSH in lysate samples. The peak integration procedure required baseline estimation and a peak fitting step to correct for background interferences while the spectral subtraction procedure was comparatively straightforward. The level of GSH measured by (1)H NMR was in good agreement with the concentration measured by the DTNB-GSSG reductase recycling assay. The proposed NMR method can lead to a reliable quantitation of GSH and could be applicable to a variety of other analytes of interest in complex biological matrices. PMID:23471371

Rhieu, Steve Y; Urbas, Aaron A; Lippa, Katrice A; Reipa, Vytas

2013-03-08

392

A simple scheme for probehead background suppression in one-pulse 1H NMR.  

PubMed

A very simple method for reducing probehead background signal in one-pulse 1H nuclear magnetic resonance (NMR) spectra is presented. Two one-pulse spectra are recorded, the first with pulse length tp1, the second with an L-times longer pulse, e.g. with L = 2. The second spectrum scaled by 1/L is subtracted from the first. Since the weak pulses experienced by spins outside the coil are in the linear regime, the background from outside the coil is effectively subtracted out. The background suppression efficiency is approximately 1.5b2, where b is the ratio of the B1 field inside the coil relative to that outside the coil. Experimentally, background suppression by at least a factor of 10 was achieved. Examples of background suppression in 1H wideline as well as 1H fast magic-angle spinning (MAS) one-pulse spectra of clay and polymer samples are shown. PMID:15157534

Chen, Q; Hou, S S; Schmidt-Rohr, K

2004-08-01

393

Protein-induced water 1H MR frequency shifts: contributions from magnetic susceptibility and exchange effects.  

PubMed

Defining the biophysics underlying the remarkable MRI phase contrast reported in high field MRI studies of human brain would lead to more quantitative image analysis and more informed pulse sequence development. Toward this end, the dependence of water (1)H resonance frequency on protein concentration was investigated using bovine serum albumin (BSA) as a model system. Two distinct mechanisms were found to underlie a water (1)H resonance frequency shift: (i) a protein-concentration-induced change in bulk magnetic susceptibility, causing a shift to lower frequency, and (ii) exchange of water between chemical-shift distinct environments, i.e., free (bulk water) and protein-associated ("bound") water, including freely exchangeable (1)H sites on proteins, causing a shift to higher frequency. At 37 degrees C the amplitude of the exchange effect is roughly half that of the susceptibility effect. PMID:19879785

Luo, Jie; He, Xiang; d'Avignon, D Andre'; Ackerman, Joseph J H; Yablonskiy, Dmitriy A

2009-10-30

394

Protein-induced water 1H MR frequency shifts: Contributions from magnetic susceptibility and exchange effects  

NASA Astrophysics Data System (ADS)

Defining the biophysics underlying the remarkable MRI phase contrast reported in high field MRI studies of human brain would lead to more quantitative image analysis and more informed pulse sequence development. Toward this end, the dependence of water 1H resonance frequency on protein concentration was investigated using bovine serum albumin (BSA) as a model system. Two distinct mechanisms were found to underlie a water 1H resonance frequency shift: (i) a protein-concentration-induced change in bulk magnetic susceptibility, causing a shift to lower frequency, and (ii) exchange of water between chemical-shift distinct environments, i.e., free (bulk water) and protein-associated (“bound”) water, including freely exchangeable 1H sites on proteins, causing a shift to higher frequency. At 37 °C the amplitude of the exchange effect is roughly half that of the susceptibility effect.

Luo, Jie; He, Xiang; D'Avignon, D. Andre'; Ackerman, Joseph J. H.; Yablonskiy, Dmitriy A.

2010-01-01

395

Multislice 1H magnetic resonance spectroscopic imaging: assessment of epilepsy, Alzheimer's disease, and amyotrophic lateral sclerosis  

NASA Astrophysics Data System (ADS)

Proton magnetic resonance spectroscopic imaging (1H MRSI) with volume pre-selection (i.e. by PRESS) or multislice 1H MRSI was used to investigate changes in brain metabolites in Alzheimer's disease, epilepsy, and amyotrophic lateral sclerosis. Examples of results from several ongoing clinical studies are provided. Multislice 1H MRSI of the human brain, without volume pre-selection offers considerable advantages over previously available techniques. Furthermore, MRI tissue segmentation and completely automated spectra curve fitting greatly facilitate quantitative data analysis. Future efforts will be devoted to obtaining full brain coverage and data acquisition at short spin echo times (TE less than 30 ms) for the detection of metabolites with short T2 relaxation times.

Weiner, Michael W.; Maudsley, Andrew A.; Schuff, Norbert; Soher, Brian J.; Vermathen, Peter P.; Fein, George; Laxer, Kenneth D.

1998-07-01

396

Effect of fertilizers on galanthamine and metabolite profiles in Narcissus bulbs by 1H NMR.  

PubMed

Narcissus bulbs contain the biologically active alkaloid galanthamine, and Narcissus is being developed as a natural source of the molecule for the pharmaceutical industry. The effect of fertilizer on galanthamine production was investigated in a field study using a (1)H nuclear magnetic resonance (NMR) metabolite profiling approach. Galanthamine was quantitated and major metabolites in the bulbs were identified. The application of standard fertilization levels of nitrogen and potassium caused a significant increase in galanthamine as compared to a control. Multivariate data analysis of the (1)H NMR data revealed that applying double the standard level of nitrogen fertilizer resulted in production of more amino acids and citric acid cycle intermediates, but not more galanthamine. The results indicated that standard levels of fertilizer currently applied in The Netherlands are sufficient for optimal galanthamine accumulation in the bulbs. This study shows how (1)H NMR-based metabolic profiling can provide insight into the response of plant metabolism to agricultural practices. PMID:21375239

Lubbe, Andrea; Choi, Young Hae; Vreeburg, Peter; Verpoorte, Robert

2011-03-04

397

Substituted benzimidazo[2,1 - h ]pteridine-2,4-diones  

Microsoft Academic Search

5-Alkyl-5,6-dihydrobenzimidazo[2,1 -h]pteridine-2,4(1H,3H)-diones (4 a–d) have been synthesised by the condensation of 2-(alkyl-aminomethyl)benzimidazole dihydrochloride (1 a–d) with 5-bromobarbituric acid (2). Similarly, 5-alkyl-5,6-dihydro-4 a-nitrobenzimidazo[2,1 -h] pteridine-2,4(3H,4aH)-diones (10 a–d) have also been synthesised by the condensation of1 a–d with 5-bromo-5-nitrobarbituric acid (8) followed by cyclisation of the intermediate 5-[(benzimidazol-2-ylmethyl)alkylamino]-5-nitrobarbituric acid (9 a–d) with 5% NaOH. Thermal cyclisation of the intermediates9 a–d have also

H. K. Gakhar; Punam Sachdev; Shashi Bhushan Gupta

1984-01-01

398

PKC{delta}-mediated IRS-1 Ser24 phosphorylation negatively regulates IRS-1 function  

SciTech Connect

The IRS-1 PH and PTB domains are essential for insulin-stimulated IRS-1 Tyr phosphorylation and insulin signaling, while Ser/Thr phosphorylation of IRS-1 disrupts these signaling events. To investigate consensus PKC phosphorylation sites in the PH-PTB domains of human IRS-1, we changed Ser24, Ser58, and Thr191 to Ala (3A) or Glu (3E), to block or mimic phosphorylation, respectively. The 3A mutant abrogated the inhibitory effect of PKC{delta} on insulin-stimulated IRS-1 Tyr phosphorylation, while reductions in insulin-stimulated IRS-1 Tyr phosphorylation, cellular proliferation, and Akt activation were observed with the 3E mutant. When single Glu mutants were tested, the Ser24 to Glu mutant had the greatest inhibitory effect on insulin-stimulated IRS-1 Tyr phosphorylation. PKC{delta}-mediated IRS-1 Ser24 phosphorylation was confirmed in cells with PKC{delta} catalytic domain mutants and by an RNAi method. Mechanistic studies revealed that IRS-1 with Ala and Glu point mutations at Ser24 impaired phosphatidylinositol-4,5-bisphosphate binding. In summary, our data are consistent with the hypothesis that Ser24 is a negative regulatory phosphorylation site in IRS-1.

Greene, Michael W. [Bassett Research Institute, Mary Imogene Bassett Hospital, Cooperstown, NY 13326 (United States)]. E-mail: michael.greene@bassett.org; Ruhoff, Mary S. [Bassett Research Institute, Mary Imogene Bassett Hospital, Cooperstown, NY 13326 (United States); Roth, Richard A. [Department of Molecular Pharmacology, Stanford University School of Medicine, Stanford, CA 94305 (United States); Kim, Jeong-a [Diabetes Unit, National Center for Complementary and Alternative Medicine, National Institutes of Health, Bethesda, MD 20892 (United States); Quon, Michael J. [Diabetes Unit, National Center for Complementary and Alternative Medicine, National Institutes of Health, Bethesda, MD 20892 (United States); Krause, Jean A. [Bassett Research Institute, Mary Imogene Bassett Hospital, Cooperstown, NY 13326 (United States)

2006-10-27

399

The hydrogenphosphate complex of (1,5-cyclooctadiene)iridium(I), {[Bu 4N][(1,5COD)Ir · HPO 4]} n : synthesis, spectroscopic characterization, and ES-MS of a new, preferred precursor to HPO 4 2? and Bu 4N + stabilized Ir(0) n nanoclusters  

Microsoft Academic Search

The synthesis and characterization of a previously unknown, rare organometallic–phosphate complex, {[Bu4N][(1,5-COD)Ir·HPO4]}n (1), is described. Characterization of 1 was accomplished by elemental analysis, electrospray mass spectrometry (ES-MS), and 1H and 13C NMR which established the symmetry of the product as at least C2 or Cs. The ES-MS reveals an interesting, Ir(I) to Ir(III) oxidative process with intense peaks displaying the

Saim Özkar; Richard G. Finke

2004-01-01

400

Study of phospholipid structure by 1H, 13C, and 31P dipolar couplings from two-dimensional NMR.  

PubMed Central

Various motionally averaged 31P-1H, 13C-1H, 1H-1H, and 31P-13C dipolar couplings were measured for natural-abundance and unoriented phosphocholine in the L alpha phase. The couplings were obtained and assigned by a variety of advanced and partly novel two-dimensional solid-state NMR experiments. Whereas 31P-1H and 31P-13C dipolar couplings provide long-range structural constraints, geminal 1H-1H couplings and the signs of 13C-1H couplings are important new elements in a segmental order-tensor analysis of the lipid headgroup and glycerol backbone. The implications of these measured dipolar couplings for the conformational exchange of the lipid headgroup and the bending of the headgroup from the glycerol backbone are discussed. These dipolar couplings are also analyzed semiquantitatively in terms of the segmental order tensor. Images FIGURE 2

Hong, M; Schmidt-Rohr, K; Nanz, D

1995-01-01

401

Intramolecular 1H-13C Distance Measurement in Uniformly 13C, 15N Labeled Peptides by Solid-State NMR  

PubMed Central

A 1H-13C frequency-selective REDOR (FS-REDOR) experiment is developed for measuring intramolecular 1H-13C distances in uniformly 13C, 15N-labeled molecules. Theory and simulations show that the experiment removes the interfering homonuclear 1H-1H, 13C-13C and heteronuclear 1H-15N, 13C-15N dipolar interactions while retaining the desired heteronuclear 1H-13C dipolar interaction. Our results indicate that this technique, combined with the numerical fitting, can be used to measure a 1H-13C distance up to 5 Å. We also demonstrate that the measured intramolecular 1H-13C distances are useful to determine dihedral angles in proteins.

Li, Shenhui; Su, Yongchao; Hong, Mei

2012-01-01

402

Fine Definition of IR Spectra from High Temperature Interactions of U + O2 - Part II.  

National Technical Information Service (NTIS)

The reactions of UO and UO2 with NO and NO2 have been studied by infrared (IR) spectroscopy using the matrix-isolation technique. Codeposition of vaporized UO and UO2 with NO2 and with NO gases in an argon matrix at 14K resulted in the production of the U...

D. W. Green S. D. Gabelnick G. T. Reedy

1975-01-01

403

Novel dehydration of carbohydrates to 5-hydroxymethylfurfural catalyzed by Ir and Au chlorides in ionic liquids  

Microsoft Academic Search

Catalytic dehydration of carbohydrates into 5-hydroxymethylfurfural (5-HMF) has been studied in the presence of ionic liquids, i.e., 1-butyl-3-methyl imidazolium chloride ([BMIM]Cl) and triethylamine sulphate ([Et3NH][HSO4]) using metal salts as catalysts. Novel metal chlorides IrCl3 and AuCl3·HCl as catalysts in ionic liquid showed remarkable activity and selectivity to 5-HMF for the reaction of fructose dehydration. The reaction conditions of fructose dehydration

Zuojun Wei; Yan Li; Dilantha Thushara; Yingxin Liu; Qilong Ren

2011-01-01

404

A 500MHz 1 H-NMR study on the N -linked carbohydrate chain of bromelain  

Microsoft Academic Search

The 500-MHz1H-NMR characteristics of theN-linked carbohydrate chain Mana1-6[Xylß1-2]Manß1-4GlcNAcß1-4[Fuca1-3]GlcNAcß1-NAsn of the proteolytic enzyme bromelain (EC 3.4.22.4) from pineapple stem were determined for the oligosaccharide-alditol and the glycopeptide, obtained by hydrazinolysis and Pronase digestion, respectively. The1H-NMR structural-reporter-groups of the a(1–3)-linked fucose residue form unique sets of data for the alditol as well as for the glycopeptide.

J A Van Kuik; R A Hoffmann; J H G M Mutsaers; H Van Halbeek; J P Kamerling; J F G Vliegenthart

1986-01-01

405

Optimization of 1H spin density for dynamic nuclear polarization using photo-excited triplet electron spins  

Microsoft Academic Search

In dynamic nuclear polarization (DNP) using photo-excited triplet electron spins, known as Microwave-Induced Optical Nuclear Polarization (MIONP), the attainable 1H polarization is determined by the ratio of the buildup rate and the spin–lattice relaxation rate, in turn depend on the 1H spin density. It is shown that the final 1H polarization can be enhanced by diluting the 1H spins with

Akinori Kagawa; Yu Murokawa; Kazuyuki Takeda; Masahiro Kitagawa

2009-01-01

406

Flexible and Efficient IR Using Array Databases.  

National Technical Information Service (NTIS)

The Matrix Framework is a recent proposal by IR researchers to flexibly represent all important information retrieval models in a single multi-dimensional array framework. Computational support for exactly this framework is provided by the array database ...

A. P. De Vries M. Zukowski P. A. Boncz R. Cornacchia S. Heman

2007-01-01

407

Molecular orbital calculations of /sup 13/C-/sup 13/C and /sup 1/H-/sup 1/H nuclear spin-spin coupling constants  

SciTech Connect

Theoretical studies are presented for the conformational dependencies of vicinal /sup 13/C-/sup 13/C coupling constants within a variety of saturated and unsaturated molecular frameworks. Using the molecular orbital approach of Blizzard and Santry, it is shown that three distinct patterns of dihedral angle versus /sup 3/H/sub CC/sup contract/ coupling are produced, depending upon the degree of double bonding present within the direct coupling path. By means of calculations that involve modifying the various exchange integrals, two of these coupling patterns are found to depend on sigma-..pi.. exchange. A rationalization of the origin of these coupling patterns is presented. In all systems studied, the orbital and dipolar contributions to the vicinal coupling constant are calculated to be negligible compared to the Fermi contact mechanism except in conjugated systems. The FP/INDO molecular orbital method is employed in the investigation of substitutent effects on /sup 1/H-/sup 1/H coupling constants in substituted ethanes, ethylenes, and benzenes. Substituent effects are simulated by varying the (1/2)(I + A) INDO parameters on two different types of pseudoatoms, one essentially a pseudo-hydrogen and the other involving 2s and 2p orbitals on two centers. A review of the theory of nuclear spin-spin coupling is presented.

Severson, M.L.

1984-01-01

408

Elevated Glutamatergic Compounds in Pregenual Anterior Cingulate in Pediatric Autism Spectrum Disorder Demonstrated by 1H MRS and 1H MRSI  

PubMed Central

Recent research in autism spectrum disorder (ASD) has aroused interest in anterior cingulate cortex and in the neurometabolite glutamate. We report two studies of pregenual anterior cingulate cortex (pACC) in pediatric ASD. First, we acquired in vivo single-voxel proton magnetic resonance spectroscopy (1H MRS) in 8 children with ASD and 10 typically developing controls who were well matched for age, but with fewer males and higher IQ. In the ASD group in midline pACC, we found mean 17.7% elevation of glutamate + glutamine (Glx) (p<0.05) and 21.2% (p<0.001) decrement in creatine + phosphocreatine (Cr). We then performed a larger (26 subjects with ASD, 16 controls) follow-up study in samples now matched for age, gender, and IQ using proton magnetic resonance spectroscopic imaging (1H MRSI). Higher spatial resolution enabled bilateral pACC acquisition. Significant effects were restricted to right pACC where Glx (9.5%, p<0.05), Cr (6.7%, p<0.05), and N-acetyl-aspartate + N-acetyl-aspartyl-glutamate (10.2%, p<0.01) in the ASD sample were elevated above control. These two independent studies suggest hyperglutamatergia and other neurometabolic abnormalities in pACC in ASD, with possible right-lateralization. The hyperglutamatergic state may reflect an imbalance of excitation over inhibition in the brain as proposed in recent neurodevelopmental models of ASD.

Bejjani, Anthony; O'Neill, Joseph; Kim, John A.; Frew, Andrew J.; Yee, Victor W.; Ly, Ronald; Kitchen, Christina; Salamon, Noriko; McCracken, James T.; Toga, Arthur W.; Alger, Jeffry R.; Levitt, Jennifer G.

2012-01-01

409

Reactions & Rates  

NSDL National Science Digital Library

Explore what makes a reaction happen by colliding atoms and molecules. Design experiments with different reactions, concentrations, and temperatures. When are reactions reversible? What affects the rate of a reaction?

Simulations, Phet I.; Koch, Linda; Lemaster, Ron; Loeblein, Trish; Perkins, Kathy; Gratny, Mindy

2006-12-01

410

Drug Reactions  

MedlinePLUS

... version Drug Reactions Drug Reactions What is an adverse drug reaction? Medicines can treat or prevent illness ... medicines can cause problems. These problems are called adverse drug reactions. You should know what to do ...

411

On Dead OH/IR Stars  

NASA Astrophysics Data System (ADS)

Because the net duration of all 1612 MHz emission phases from |b|>10deg OH/IR stars is ~1700 yr, one ``death,'' as evidenced by the disappearance of all 1612 MHz masers, should occur in a sample of 170 every 10 yr, on average, if they have only one emission phase. We report here on the reobservation after 12 yr of the 328 OH/IR stars in the Arecibo sky with a peak first-epoch I1612>100 mJy. Four of these now have undetectable 1612 MHz masers, while those from a fifth, FV Boo, appear to be in terminal decline. The blue IR colors, 315 day period of FV Boo, and presence of water and SiO masers in several of the newly identified dead OH/IR stars all suggest that these objects are still asymptotic giant branch (AGB) stars rather than proto-planetary nebulae. This conclusion suggests that most oxygen-rich AGB stars pass through the OH/IR star phase more than once. The positions of the dead OH/IR stars on first-epoch plots of I1612 versus S(25) and on plots of the ratio of these quantities versus IR color are entirely normal. However, all of the dead OH/IR stars have small, less than 12 km s-1, expansion velocities, and all but one have blue IR colors. When these criteria are used to further delimit the sample, the five dead OH/IR stars in a sample of 112 imply a mean 1612 MHz emission life te~314 (+387, -97) yr. The short duration of this emission phase is readily understood if oxygen-rich AGB stars toward the end of the AGB pass through a brief OH/IR star phase after a thermal pulse, when, as often happens, they are not bright enough to support heavy mass loss on the luminosity ascent to a thermal pulse. Copious AGB mass loss is thus frequently triggered by events that follow a thermal pulse.

Lewis, B. M.

2002-09-01

412

Multiview: a novel multispectral IR imaging camera  

Microsoft Academic Search

The Surveillance Sciences Directorate of the Northrop Grumman Advanced Systems and Technology organization is developing a novel Multispectral IR camera known as Multiview. This prototype system is capable of simultaneously acquiring 4-color SWIR\\/MWIR 2D imagery that is both spatially and temporally registered utilizing a single 2562 HgCdTe snapshot IR FPA capable of frame rates in excess of 240 Hz. The

Michael A. Soel; Stanley Rudman; Robert Ryan; Nils J. Fonneland; Steve Milano

1997-01-01

413

IR Optimization, DID and anti-DID  

SciTech Connect

In this paper, we discuss optimization of the larger crossing angle Interaction Region of the Linear Collider, where specially shaped transverse field of the Detector Integrated Dipole can be reversed and adjusted to optimize trajectories of the low energy pairs, so that their majority would be directed into the extraction exit hole. This decreases the backscattering and makes background in 14mrad IR to be similar to background in 2mrad IR.

Seryi, Andrei; Maruyama, Takashi; /SLAC; Parker, Brett; /Brookhaven

2006-02-03

414

ACTIVE MEDIA Kinetics of O2(1?) self-quenching in the O2 — O2(1?) — H2O gas mixture  

NASA Astrophysics Data System (ADS)

The self-quenching kinetics of O2(1?) molecules in the O2 — O2(1?) — H2O gas mixture produced by a chemical singlet-oxygen generator for an oxygen—iodine laser is investigated. The rate of change in the O2(1?) concentration in continuous-flow tube is determined by measuring the absolute spectral irradiance of the O2 — O2(1?) — H2O gas mixture in the ranges of 600 — 800 nm and 1210 — 1330 nm. The effective rate constant of O2(1?) deactivation in all possible channels of the O2(1?) + O2(1?) ? products reaction is found to be (8±1.2)×10-17 cm3 s-1.

Zagidullin, M. V.; Khvatov, N. A.

2010-11-01

415

6-Substituted 1H-quinolin-2-ones and 2-methoxy-quinolines: synthesis and evaluation as inhibitors of steroid 5alpha reductases types 1 and 2.  

PubMed

A Negishi-type coupling reaction between 6-bromo-2-methoxyquinoline (1a) and various 4-bromo-N,N-dialkyl-benzamides gave access to 6-substituted 2-methoxy-quinolines 1-3 and 1H-quinolin-2-ones 4-12. Most of these compound proved to be inhibitors of steroid 5alpha reductases with activity and selectivity both being strongly dependent on the features of the heterocycle and the size of the N,N-dialkylamide substituent. The most active inhibitor for the human type 2 isozyme was 6-[4-(N,N-diisopropylcarbamoyl)phenyl]-1H-quinolin-2-one 4 (Ki 800 +/- 85 nM), showing mostly competitive inhibitory patterns. A type 1 selective inhibitor could be identified with 6-[4-(N,N-diisopropylcarbamoyl)phenyl]-N-methyl-quinolin-2-one (5, IC50 510 nM). PMID:11121619

Baston, E; Palusczak, A; Hartmann, R W

2000-10-01

416

Molecular structure of 4-benzoyl-3-ethylcarboxylate 1-(4-methoxyphenyl)-5-phenyl-1H-pyrazole: A combined experimental and theoretical study  

NASA Astrophysics Data System (ADS)

The title molecule, 4-benzoyl-3-ethylcarboxylate 1-(4-methoxyphenyl)-5-phenyl-1H-pyrazole, (C26H22N2O4), was synthesized and characterized by IR-NMR spectroscopy and single-crystal X-ray diffraction. In addition to the molecular geometry from X-ray experiment, the molecular geometry, vibrational frequencies and gauge-independent atomic orbital (GIAO) 1H and 13C NMR chemical shift values of the title compound in the ground state have been calculated using the spin-restricted Hartree-Fock (HF) and density functional theory (DFT/B3LYP) method with the 6-31G (d, p) basis set, and compared with the experimental data. To determine conformational flexibility, molecular energy profile of the tittle compound was obtained by semi-empirical (AM1) with respect to selected degree of torsional freedom, which was varied from -180° to +180° in steps 10°. Besides, molecular electrostatic potential (MEP) distribution, frontier molecular orbitals (FMOs) and thermodynamic properties of the title molecule were investigated by theoretical calculations at the B3LYP/6-31G (d, p) level.

?nkaya, Ersin; Dinçer, Muharrem; Korkusuz, Elif; Yildirim, ?smail

2012-04-01

417

Synthesis, spectroscopic characterization and quantum chemical computational studies on 1-acetyl-3,5-di(4-methylphenyl)-1H-pyrazole  

NASA Astrophysics Data System (ADS)

The pyrazole compound 1-acetyl-3,5-di(4-methylphenyl)-1H-pyrazole, (C19H18N2O), was characterized by X-ray single crystal diffraction technique, IR-NMR spectroscopy and quantum chemical computational methods as both experimental and theoretically. The compound crystallizes in the monoclinic space group C 2/c with a = 32.5334 (1) Å, b = 5.8060 (1) Å, c = 23.6519 (8) Å, ? = 134.572 (2)°, and Z = 8. The molecular geometry was also optimized using the Hartree-Fock (HF) and density functional theory (DFT/B3LYP) methods with the 6-311G(d,p) basis set and compared with the experimental data. To determine conformational flexibility, molecular energy profile of the tittle compound was obtained by semi-empirical (AM1) with respect to selected degree of torsional freedom, which was varied from -180° to +180° in steps 10°. From the optimized geometry of the molecule, vibrational frequencies, gauge-independent atomic orbital (GIAO) 1H and 13C NMR chemical shift values, molecular electrostatic potential (MEP) distribution, non-linear optical properties, frontier molecular orbitals (FMOs) of the title compound have been calculated in the ground state theoretically. The theoretical result showed good agreement with the experimental values.

?nkaya, Ersin; Dinçer, Muharrem; Korkusuz, Elif; Yildirim, ?smail; Büyükgüngör, Orhan

2012-11-01

418

Synthesis, spectroscopic and structural characterization of 5-benzoyl-4-phenyl-2-methylthio-1H-pyrimidine with theoretical calculations using density functional theory  

NASA Astrophysics Data System (ADS)

In this paper, we will report a combined experimental and theoretical investigation of the molecular structure and spectroscopic parameters (FT-IR, 1H NMR, 13C NMR) of 5-benzoyl-4-phenyl-2-methylthio-1H-pyrimidine. The compound crystallizes in the triclinic space group P-1 with Z = 2. The molecular geometry was also optimized using density functional theory (DFT/B3LYP) method with the 6-311G(d,p) and 6-311++G(d,p) basis sets in ground state and compared with the experimental data. All the assignments of the theoretical frequencies were performed by potential energy distributions using VEDA 4 program. Information about the size, shape, charge density distribution and site of chemical reactivity of the molecules has been obtained by mapping electron density isosurface with electrostatic potential (ESP). Also, non-linear optical properties of the title compound were performed at B3LYP/6-311++G(d,p) level. The theoretical results showed an excellent agreement with the experimental values.

?nkaya, Ersin; Dinçer, Muharrem; ?ahan, Emine; Y?ld?r?m, ?smail

2013-10-01

419

Synthesis, photoluminescence properties and theoretical insights on 1,3-diphenyl-5-(9-anthryl)-2-pyrazoline and -1H-pyrazole.  

PubMed

1,3-Diphenyl-5-(9-anthryl)-2-pyrazoline and 1,3-diphenyl-5-(9-anthryl)-1H-pyrazole with an anthryl chromophore were synthesized and characterized using (1) H NMR, (13) C NMR, FT-IR, mass spectrometry and elemental analysis. Their optical properties were characterized by UV-vis absorption and fluorescence spectroscopy. It was observed that the absorption and fluorescence spectra of the two compounds showed a red shift with respect to that of anthracene. Pyrazole exhibited high fluorescent quantum yields (?f ?=?0.90 in toluene) while pyrazoline showed nearly no fluorescence in solution. The significant fluorescence divergence of the two similar compounds was investigated theoretically through density functional theory (DFT) calculations. The energetically lowest-lying state S1 in the pyrazoline exhibited both characteristics of locally excited and electron-transfer states that resulted in the fluorescence quenching of anthryl chromophore whereas the S1 state in the pyrazole corresponded to an optically allowed state that led to high fluorescence quantum yields in solutions. Copyright © 2012 John Wiley & Sons, Ltd. PMID:22829359

Dong, Baoli; Wang, Mingliang; Xu, Chunxiang

2012-07-24

420

Synthesis and characterization of 3-methyl-5-oxo-N,1-diphenyl-4,5-dihydro-1-H-pyrazole-4-carbothioamide and its metal complexes  

NASA Astrophysics Data System (ADS)

The molecular parameters have been calculated to confirm the geometry of 3-methyl-5-oxo-N,1-diphenyl-4,5-dihydro-1-H-pyrazole-4-carbothioamide, HL. The compound is introduced as a new chelating agent for complexation with Cr(III), Fe(III), Co(II), Ni(II) and Cu(II) ions. The isolated chelates were characterized by partial elemental analyses, magnetic moments, spectra (IR, UV-vis, ESR; 1H NMR) and thermal studies. The protonation constant of HL (5.04) and the stepwise stability constants of its Co(II), Cu(II), Cr(III) and Fe(III) complexes were calculated. The ligand coordinates as a monobasic bidentate through hydroxo and thiol groups in all complexes except Cr(III) which acts as a monobasic monodentate through the enolized carbonyl oxygen. Cr(III) and Fe(III) complexes measured normal magnetic moments; Cu(II) and Co(II) measured subnormal while Ni(II) complex is diamagnetic. The data confirm a high spin and low spin octahedral structures for the Fe(III) and Co(II) complexes. The ESR spectrum of the Cu(II) complex support the binuclear structure. The molecular parameters have also been calculated for the Cu(II) and Fe(III) complexes. The thermal decomposition stages of the complexes confirm the MS to be the residual part. Also, the thermodynamic and kinetic parameters were calculated for some decomposition steps.

El-Shazly, R. M.

2009-09-01

421

Formation of (bn?1 + H2O) Ions by Collisional Activation of MALDI-formed Peptide [M + H]+ Ions in a QqTOF Mass Spectrometer*  

PubMed Central

Collisional activation of [M + H]+ parent ions from peptides of n amino acid residues may yield a rearrangement that involves loss of the C-terminal amino acid residue to produce (bn?1+H2O) daughters. We have studied this reaction by a retrospective examination of the m/z spectra of two collections of data. The first set comprised 398 peptides from coat protein digests of a number of plant viruses by various enzymes, where conditions in the tryptic digests were chosen so as to produce many missed cleavages. In this case a large effect was observed– 323 (bn?1+H2O) daughter ions (~81%), including 185 (~ 46%) “strong” decays with ratios (bn?1+H2O)/(bn?1)>1. The second set comprised 1200 peptides, all from tryptic digests, which were carried out under more stringent conditions, resulting in relatively few missed cleavages. Even here, 190 (bn?1+H2O) ions (~ 16 %) were observed, including 87 (> 7%) “strong” decays, so the effect is still appreciable. The results suggest that the tendency for (bn?1+H2O) ion formation is promoted by the protonated side chain of a non-C-terminal basic amino acid residue, in the order arginine ? lysine ? histidine, and that its (non-C-terminal) position is not critical. The results can be interpreted by a mechanism in which hydrogen bonding between the protonated side chain and the (n-1) carbonyl oxygen facilitates loss of the C-terminal amino acid residue to give a product ion having a carboxyl group at the new C-terminus.

She, Yi-Min; Krokhin, Oleg; Spicer, Victor; Loboda, Alexandre; Garland, Gideon; Ens, Werner; Standing, Kenneth G.; Westmore, John B.

2007-01-01

422

Isolated gramicidin peptides probed by IR spectroscopy.  

PubMed

We report double-resonant IR/UV ion-dip spectroscopy of neutral gramicidin peptides in the gas phase. The IR spectra of gramicidin A and C, recorded in both the 1000 cm(-1) to 1800 cm(-1) and the 2700 to 3750 cm(-1) region, allow structural analysis. By studying this broad IR range, various local intramolecular interactions are probed, and complementary IR modes can be accessed. Ab initio quantum chemical calculations are used to support the interpretation of the experimental IR spectra. The comparison of the calculated frequencies with the experimental IR spectrum probed via the strong infrared absorptions of all the amide groups (NH stretch, C=O stretch and NH bend), shows evidence for a helical structure in the gas phase, which is similar to that in the condensed phase. Additionally, we show that to improve the spectral resolution when studying large neutral molecular structures of the size of gramicidin, the use of heavier carrier gas could be advantageous. PMID:21656894

Rijs, Anouk M; Kabelá?, Martin; Abo-Riziq, Ali; Hobza, Pavel; de Vries, Mattanjah S

2011-06-08

423

Tissue-specific insulin resistance in mice with mutations in the insulin receptor, IRS-1, and IRS-2  

Microsoft Academic Search

Type 2 diabetes is characterized by abnormalities of insulin action in muscle, adipose tissue, and liver and by altered ?-cell function. To analyze the role of the insulin signaling pathway in these processes, we have generated mice with combined heterozygous null mutations in insulin receptor (ir), insulin receptor substrate (irs-1), and\\/or irs-2. Diabetes developed in 40% of ir\\/irs-1\\/irs-2 +\\/- ,

Yoshiaki Kido; Deborah J. Burks; Dominic Withers; Jens C. Bruning; C. Ronald Kahn; Morris F. White; Domenico Accili

2000-01-01

424

Characteristics of Ni–Ir and Pt–Ir hard coatings surface treated by pulsed Nd:YAG laser  

Microsoft Academic Search

The subjects of the presented paper are to develop a laser surface treatment technology for the protective coatings of glass-molding dies and to better understand the interaction between laser beam and materials coated on the die surface. A variety of alloy films, including Ir-25 at.% Pt, Ir-50 at.% Pt, Ir-75 at.% Pt, Ir-25 at.% Ni, Ir-50 at.% Ni, and Ir-75

Shih-Feng Tseng; Wen-Tse Hsiao; Kuo-Cheng Huang; Ming-Fei Chen; Chao-Te Lee; Chang-Pin Chou

2010-01-01

425

DFT studies of structure and vibrational spectra of 4-benzylidene-1-phenyl-2-selenomorpholino-1H-imidazol-5(4H)-one and its derivatives.  

PubMed

The Raman spectra and FT-IR spectra of 4-benzylidene-1-phenyl-2-selenomorpholino-1H-imidazol-5(4H)-one and its derivatives have been measured and their ground-state geometries and vibrational spectra are studied by DFT at B3LYP/6-31G(d) level. Comparing the optimized geometries of compounds 1-6, we find that different substituent and substitution site on benzene rings result in very small changes on the imidazoline skeleton, the changes on bond length are within 0.005 Å and on bond angle are within 0.5°. Calculated spectra are well consistent with the experimental one and the deviations are smaller than 30 cm-1. The influence of substituent on IR and Raman spectrum must not be neglected. Electron-withdrawing chlorine atom makes the stretching vibration of carbonyl group shift 4-16 cm(-1) towards higher wavenumber, but electron-donating methoxyl group and dioxole group make it shift 6-10 cm(-1) in IR and 9-13 cm(-1) in Raman spectrum towards lower wavenumber, respectively. Dioxole substitution makes the C=C stretching vibration of phenyl shift to a higher position at 1617-1618 cm(-1). The influence of intermolecular weak interaction on vibrational spectrum is studied by two models (dimer and monomer inclusion van del Waals correction). Dimer model presents a better accuracy, but van del Waals correction on B3LYP hybrid function does not produce a significant change on accuracy in this system. PMID:23583851

Zhou, Shuli; You, Bin; Yao, Qi; Chen, Meng; Wang, Yujiao; Li, Wei

2013-03-25

426

Novel palladium(II) and platinum(II) complexes with 1H-benzimidazol-2-ylmethyl-N-(4-bromo-phenyl)-amine: structural studies and anticancer activity.  

PubMed

[MLCl(2)] (L = (1H-benzimidazol-2-ylmethyl)-N-(4-bromo-phenyl)-amine; M = Pd & Pt) and [PdL(OH(2))(2)]?2X?zH(2)O (X = Br, I, z = 2; X = SCN, z = 1; X = NO(3), z = 0) complexes have been synthesized as potential anticancer compounds and their structures were elucidated using elemental analysis, spectral, thermal analysis and X-ray powder diffraction. The benzimidazole (L) crystallizes in the space group P2(1)/c with a = 8.6660(3) Å, b = 16.6739(7) Å, c = 9.8611(4) Å and ? = 113.505(3) ° and forms an infinite chain structure with a trans-zigzag type along the crystallographic axis "a", through the intermolecular H-bond. FT-IR and (1)H NMR studies revealed that the ligand L is coordinated to the metal ion via the pyridine-type nitrogen (N(py)) of the benzimidazole ring and secondary amino group (NH(sec)). Quantum mechanical calculations of energies, geometries, vibrational wavenumbers, and (1)H NMR of the benzimidazole L and its complexes were carried out by DFT/B3LYP method combined with 6-31G(d) and LANL2DZ basis sets. Natural bond orbital (NBO) analysis and frontier molecular orbitals (FMO) were performed at B3LYP/LANL2DZ level of theory. The benzimidazole L, in comparison to its metal complexes was screened for its antibacterial activity. The complexes showed cyctotoxic effects against human breast cancer (MCF7), hepatocarcinoma (HepG(2)) and colon carcinoma cells (HCT). The platinum complex (6) exhibited a moderate antitumor activity against MCF7 with IC(50) = 10.2 ?M comparing to that reported for cis-platin 9.91 ?M. PMID:22119126

Abdel Ghani, Nour T; Mansour, Ahmed M

2011-11-15

427

Structural and in vitro cytotoxicity studies on 1H-benzimidazol-2-ylmethyl-N-phenyl amine and its Pd(II) and Pt(II) complexes.  

PubMed

[MLCl(2)]·zH(2)O (L = (1H-benzimidazol-2-ylmethyl)-N-phenyl amine; M = Pd, z = 0; M = Pt, z = 1) and [PdL(OH(2))(2)]·2X·zH(2)O (X = Br, I, NO(3), z = 0; X = SCN, z = 1) complexes were synthesized as potential anticancer compounds and characterized by elemental analysis, spectral and thermal methods. FT-IR and (1)H NMR studies revealed that the benzimidazole L is coordinated to the metal ions via the pyridine-type nitrogen (N(py)) of the benzimidazole ring and secondary amino group (NH(sec)). Quantum mechanical calculations of energies, geometries, vibrational wavenumbers, and (1)H NMR of the benzimidazole L and its complexes were carried out by density functional theory using B3LYP functional combined with 6-31G(d) and LANL2DZ basis sets. Natural bond orbitals (NBOs) and frontier molecular orbitals were performed at B3LYP/LANL2DZ level of theory. The synthesized ligand, in comparison to its metal complexes was screened for its antibacterial activity. The benzimidazole L is more toxic against the bacterium Staphylococcus aureus (MIC = 58 ?g/mL) than the standard tetracycline (MIC = 82 ?g/mL). The complexes showed cytotoxicity against breast cancer, Colon Carcinoma, and human heptacellular Carcinoma cells. The platinum complex (6) displays cytotoxicity (IC(50) = 12.4 ?M) against breast cancer compared with that reported for cis-platin 9.91 ?M. PMID:21763187

Abdel Ghani, Nour T; Mansour, Ahmed M

2011-06-24

428

10B-editing 1H-detection and 19F MRI strategies to optimize boron neutron capture therapy.  

PubMed

Boron neutron capture therapy (BNCT) is a binary radiation therapy used to treat malignant brain tumours. It is based on the nuclear reaction (10B + n th --> [11B*] --> alpha + 7Li + 2.79 MeV) that occurs when 10B captures a thermal neutron to yield alpha particles and recoiling 7Li nuclei, both responsible of tumour cells destruction by short range and high ionization energy release. The clinical success of the therapy depends on the selective accumulation of the 10B carriers in the tumour and on the high thermal neutron capture cross-section of 10B. Magnetic resonance imaging (MRI) methods provide the possibility of monitoring, through 10B nuclei, the metabolic and physiological processes suitable to optimize the BNCT procedure. In this study, spatial distribution mapping of borocaptate (BSH) and 4-borono-phenylalanine (BPA), the two boron carriers used in clinical trials, has been obtained. The BSH map in excised rat brain and the 19F-BPA image in vivo rat brain, representative of BPA spatial distribution, were reported. The BSH image was obtained by means of double-resonance 10B-editing 1H-detection sequence, named M-Bend, exploiting the J-coupling interaction between 10B and 1H nuclei. Conversely, the BPA map was obtained by 19F-BPA using 19F-MRI. Both images were obtained at 7 T, in C6 glioma-bearing rat brain. Our results demonstrate the powerful of non conventional MRI techniques to optimize the BNCT procedure. PMID:18486394

Capuani, Silvia; Porcari, Paola; Fasano, Fabrizio; Campanella, Renzo; Maraviglia, Bruno

2008-05-16

429

Human phase response curve to a 1 h pulse of bright white light.  

PubMed

The phase resetting response of the human circadian pacemaker to light depends on the timing of exposure and is described by a phase response curve (PRC). The current study aimed to construct a PRC for a 1 h