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1

IR, 1H NMR and DFT studies of novel bis-Betti base derivatives of 2,6-dihydroxynaphthalene: Thermodynamic control of diastereoselectivity and configurational preference  

NASA Astrophysics Data System (ADS)

Diastereoselectivity and configurational preference for synthetic reaction of novel bis-Betti base derivatives of 2,6-dihydroxynaphthalene were studied through density functional theory (DFT). Enthalpy, entropy and Gibbs free energy of reactions as well as stereochemistry, thermodynamic stability and spectroscopic analysis of products were investigated. The calculated 1H nuclear magnetic resonance (NMR) and infrared (IR) spectra of different configurations were compared to experimental data in order to find the preferred isomer. The diastereoselectivity of reaction was estimated through the calculated equilibrium distribution of stereoisomers. According to these results, preparation of bis-Betti bases is an exothermic process accompanied by a decrease in entropy. The calculated gas phase heats of formation of title compounds are positive. Since the energy difference between stereoisomers is quite small, the change of Gibbs free energy during the reaction favors one configuration over other possibilities. These results are in good agreement with the experimental observations.

Zamani, Mehdi; Shafiee, Mehdi; Keshavarz, Mohammad Hossein

2014-10-01

2

A Classical Approach in Simple Nuclear Fusion Reaction 1H2 + 1H3 using Two-Dimension Granular Molecular Dynamics Model  

E-print Network

Molecular dynamics in 2-D accompanied by granular model provides an opportunity to investigate binding between nuclei particles and its properties that arises during collision in a fusion reaction. A fully classical approach is used to observe the influence of initial angle of nucleus orientation to the product yielded by the reaction. As an example, a simplest fusion reaction between 1H2 and 1H3 is observed. Several products of the fusion reaction have been obtained, even the unreported ones, including temporary 2He4 nucleus.

Sparisoma Viridi; Rizal Kurniadi; Abdul Waris; Yudha Satya Perkasa

2011-09-10

3

A classical approach in simple nuclear fusion reaction {sub 1}H{sup 2}+{sub 1}H{sup 3} using two-dimension granular molecular dynamics model  

SciTech Connect

Molecular dynamics in 2-D accompanied by granular model provides an opportunity to investigate binding between nuclei particles and its properties that arises during collision in a fusion reaction. A fully classical approach is used to observe the influence of initial angle of nucleus orientation to the product yielded by the reaction. As an example, a simplest fusion reaction between {sub 1}H{sup 2} and {sub 1}H{sup 3} is observed. Several products of the fusion reaction have been obtained, even the unreported ones, including temporary {sub 2}He{sup 4} nucleus.

Viridi, S.; Kurniadi, R.; Waris, A.; Perkasa, Y. S. [Nuclear Physics and Biophysics Research Division, Institut Teknologi Bandung, Bandung 40132 (Indonesia); Doctoral Program in Physics, Institut Teknologi Bandung, Bandung 40132 Physics Department, Universitas Islam Negeri Sunan Gunung Djati, Bandung 40614 (Indonesia)

2012-06-06

4

Competing reaction channels in IR-laser-induced unimolecular reactions  

SciTech Connect

The competing reaction channels in the unimolecular decomposition of two molecules, formaldehyde and tetralin were studied. A TEA CO/sub 2/ laser was used as the excitation source in all experiments. The dissociation of D/sub 2/CO was studied by infrared multiphoton dissociation (MPD) and the small-molecule nature of formaldehyde with regard to MPD was explored. The effect of collisions in MPD were probed by the pressure dependence of the MPD yield and ir fluorescence from multiphoton excited D/sub 2/CO. MPD yield shows a near cubic dependence in pure D/sub 2/CO which is reduced to a 1.7 power dependence when 15 torr of NO is added. The peak amplitude of 5 ..mu..m ir fluorescence from D/sub 2/CO is proportional to the square of the D/sub 2/CO pressure in pure D/sub 2/CO or in the presence of 50 torr of Ar. Results are explained in terms of bottlenecks to excitation at the v = 1 level which are overcome by a combination of vibrational energy transfer and rotational relaxation. The radical/molecule branching ratio in D/sub 2/CO MPD was 0.10 +- 0.02 at a fluence of 125 J/cm/sup 2/ at 946.0 cm/sup -1/. The barrier height to molecular dissociation was calculated to be 3.6 +- 2.0 kcal/mole below the radical threshold or 85.0 +- 3.0 kcal/mole above the ground state of D/sub 2/CO. In H/sub 2/CO, this corresponds to 2.5 +- 2.0 kcal/mole below the radical threshold or 83.8 +- 3.0 kcal/mole above the ground state. Comparison with uv data indicate that RRKM theory is an acceptable description of formaldehyde dissociation in the 5 to 10 torr pressure range. The unimolecular decomposition of tetralin was studied by MPD and SiF/sub 4/ - sensitized pyrolysis. Both techniques induce decomposition without the interference of catalytic surfaces. Ethylene loss is identified as the lowest energy reaction channel. Dehydrogenation is found to result from step-wise H atom loss. Isomerization via disproportionation is also identified as a primary reaction channel.

Berman, M.R.

1981-01-01

5

UV-vis, IR and 1H NMR spectroscopic studies and characterization of ionic-pair crystal violet-oxytetracycline  

NASA Astrophysics Data System (ADS)

The present study shows the formation and characterization of the ionic-pair between the antibiotic oxytetracycline and the dye crystal violet in ammonia solution pH 9.0 ± 0.2 extracted into chloroform. The characterization was demonstrated using UV-vis spectrophotometry, 1H NMR, measurement of relaxation times T1 and IR spectroscopy, using a comparison between the signals of individual pure compounds with the signals with the mixture CV-OTC in different alkaline media. The formation of ionic-pair was also corroborated by new signals and chemical shifts. (2D) NMR spectroscopy experiments show that the interaction is electrostatic.

Orellana, Sandra; Soto, César; Toral, M. Inés

2010-01-01

6

L-glutamine: Dynamical properties investigation by means of INS, IR, RAMAN, 1H NMR and DFT techniques  

NASA Astrophysics Data System (ADS)

Vibrational spectra of L-glutamine in the solid state were studied using the inelastic neutron scattering (INS), infrared (IR), Raman and 1H NMR spectroscopy techniques. DFT calculation using CASTEP code with the periodic boundary conditions was used to determine and describe the normal modes in the vibrational spectra of pure L-glutamine. An excellent agreement between the calculated and experimental INS, IR and Raman data has been found. Bands assigned to the stretching vibrations of the NH3+ group in hydrogen bonds are observed at 2400, 2618 and 2619 cm-1, while the NH3+ torsion vibration mode is observed at 441 cm-1. The band at 2041 cm-1 is assigned to combinations of the NH3+ bending symmetry vibration and the CO2- rocking vibration and can be used as an “indicator band” for the identification of the NH3+ groups in amino acid. For the L-glutamine an activation energy needed for the NH3+ group reorientation was obtained as 7.4 kcal/mol. It was found, that the combination three spectroscopic methods (INS, IR and Raman) with calculations for the crystal state proved to be an effective tool to investigate dynamical properties of amino acid crystals.

Pawlukoj?, A.; Ho?derna-Natkaniec, K.; Bator, G.; Natkaniec, I.

2014-10-01

7

Measurement of the 1H(?,?p)?0 reaction using a novel nucleon spin polarimeter.  

PubMed

We report the first large-acceptance measurement of polarization transfer from a polarized photon beam to a recoiling nucleon. The measurement pioneers a novel polarimetry technique, which can be applied to many other nuclear and hadron physics experiments. The commissioning reaction of 1H(?,?p)?0 in the range 0.4

Sikora, M H; Watts, D P; Glazier, D I; Aguar-Bartolomé, P; Akasoy, L K; Annand, J R M; Arends, H J; Bantawa, K; Beck, R; Bekrenev, V S; Berghäuser, H; Braghieri, A; Branford, D; Briscoe, W J; Brudvik, J; Cherepnya, S; Codling, R F B; Demissie, B T; Downie, E J; Drexler, P; Fil'kov, L V; Freehart, B; Gregor, R; Hamilton, D; Heid, E; Hornidge, D; Howdle, D A; Jaegle, I; Jahn, O; Jude, T C; Kashevarov, V L; Keshelashvili, I; Kondratiev, R; Korolija, M; Kotulla, M; Koulbardis, A A; Kruglov, S P; Krusche, B; Lisin, V; Livingston, K; MacGregor, I J D; Maghrbi, Y; Manley, D M; Marinides, Z; Martinez, M; McGeorge, J C; McKinnon, B; McNicoll, E F; Mekterovic, D; Metag, V; Micanovic, S; Middleton, D G; Mushkarenkov, A; Nefkens, B M K; Nikolaev, A; Novotny, R; Ostrick, M; Otte, P B; Oussena, B; Pedroni, P; Pheron, F; Polonski, A; Prakhov, S; Robinson, J; Rosner, G; Rostomyan, T; Schumann, S; Sober, D I; Starostin, A; Strakovsky, I I; Suarez, I M; Supek, I; Thiel, M; Thomas, A; Unverzagt, M; Werthmüller, D; Workman, R L; Zamboni, I; Zehr, F

2014-01-17

8

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

9

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

PubMed

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). PMID:22544980

Bhanushali, Mayur; Zhao, Cong-Gui

2012-01-18

10

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

11

Induced Polarization in the $^2$H($?,\\vec n$)$^1$H Reaction at Low Energy  

E-print Network

The induced polarization, $P^\\prime_y$, of the neutron in the deuteron photo-disintegration from threshold up to 30 MeV is calculated using a variety of different, latest-generation potentials--Argonne $v_{18}$, Bonn 2000, and Nijmegen I-- and a realistic model for the nuclear electromagnetic current operator, including one- and two-body terms. The model dependence of the theoretical predictions is found to be very small. These predictions are systematically larger in magnitude than the measured $P^\\prime_y$ values, and corroborate the conclusions of an earlier, and much older, study. There is considerable scatter in the available experimental data. New and more accurate measurements of the induced polarization in the $^2$H($\\gamma,\\vec n$)$^1$H reaction are needed in order to establish unequivocally whether there is a discrepancy between theory and experiment.

R. Schiavilla

2005-05-25

12

Stereochemistry of the reaction catalysed by 2-aminoethylphosphonate aminotransferase. A 1H-NMR study.  

PubMed

(R)- and (S)-2-amino[2-D1]ethylphosphonic acids ([2-D1]AEP) were synthesised to investigate the stereochemistry of the reaction catalysed by 2-aminoethlphosphonate aminotransferase from Pseudomonas aeruginosa. This enzyme catalyses the transfer of the amino group of AEP to pyruvate to produce 2-phosphonoacetaldehyde and alanine. The enzymic reaction proceeding through the abstraction of a proton from the Schiff-base complex formed between the enzyme-bound pyridoxal 5'-phosphate, and the substrate, was carried out in an aqueous buffer at pH 8.5; it was followed by high-field 1H-NMR measurements (500 MHz, H2O) on an AMX 500 Bruker spectrometer. The spectra, recorded with chiral (R)- or (S)-[2-D1]AEP, both showed the methylenic signal (3.0 ppm), whereas (S)-[2-D1]AEP gave the additional aldehydic signal (CHO, 9.6 ppm). These data clearly show that AEP-aminotransferase catalyses the abstraction of the pro-S hydrogen atom at the prochiral C2 carbon of AEP. Furthermore, careful timing of NMR measurements over a 2-hour period allows us to show the occurrence of an isotopic effect. PMID:8394813

Lacoste, A M; Dumora, C; Balas, L; Hammerschmidt, F; Vercauteren, J

1993-08-01

13

Diastereoselective intermolecular ene reactions: synthesis of 4,5,6,7-tetrahydro-1H-benzo[d]imidazoles.  

PubMed

The Diels-Alder cycloadducts of 4-vinylimidazoles and N-phenylmaleimide are shown to undergo facile intermolecular ene reactions. Overall the reaction of three simple molecules (a diene, a dienophile and an enophile) in a two-step process gives 4,5,6,7-tetrahydro-1H-benzo[d]imidazoles with high yields, high atom economy and diastereocontrol of up to 5 new stereocentres. PMID:22801593

Watson, Lynsey J; Harrington, Ross W; Clegg, William; Hall, Michael J

2012-09-01

14

DFT simulations, FT-IR, FT-raman, and FT-NMR spectra of 4-(4-chlorophenyl)-1H-imidazole molecules  

NASA Astrophysics Data System (ADS)

The FT-IR, FT-Raman and FT-NMR spectra of the compound 4-(4-Chlorophenyl)-1H-imidazole (4-ClPI) was recorded and analyzed. Density functional method has been used to compute optimized geometry, vibrational wavenumbers and NMR spectra of the 4-ClPI. Only one tautomeric form was found most stable by using B3LYP functional with the 6-311++G( d, p) as basis sets. The detailed interpretation of the vibrational spectra was carried out with the aid of total energy distribution (TED) following the scaled quantum mechanical force field methodology.

Erdogdu, Y.; Güllüo?lu, M. T.; Yurdakul, S.; Dereli, Ö.

2012-07-01

15

Experimental (FT-IR, FT-Raman, UV-Vis, 1H and 13C NMR) and computational (density functional theory) studies on 3-bromophenylboronic acid  

NASA Astrophysics Data System (ADS)

Structurally, boronic acids are trivalent boron-containing organic compounds that possess one alkyl substituent (i.e., C-Br bond) and two hydroxyl groups to fill the remaining valences on the boron atom. We studied 3-bromophenylboronic acid (3BrPBA); a derivative of boronic acid. This study includes the experimental (FT-IR, FT-Raman, 1H and 13C NMR, UV-Vis) techniques and theoretical (DFT-density functional theory) calculations. The experimental data are recorded, FT-IR (4000-400 cm-1) and FT-Raman spectra (3500-10 cm-1) in the solid phase. 1H and 13C NMR spectra are recorded in DMSO solution. UV-Vis spectrum is recorded in the range of 200-400 nm for each solution (in ethanol and water). The theoretical calculations are computed DFT/B3LYP/6-311++G(d,p) basis set. The optimum geometry is also obtained from inside for possible four conformers using according to position of hydrogen atoms after the scan coordinate of these structures. The fundamental vibrations are assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and parallel quantum solutions (PQS) program. 1H and 13C NMR chemical shifts are racked on by using the gauge-invariant atomic orbital (GIAO) method. The time-dependent density functional theory (TD-DFT) is used to find HOMO and LUMO energies, excitation energies, oscillator strengths. The density of state of the studied molecule is investigated as total and partial density of state (TDOS and PDOS) and overlap population density of state (OPDOS or COOP) diagrams have been presented. Besides, frontier molecular orbitals (FMOs), molecular electrostatic potential surface (MEPs) and thermodynamic properties are performed. At the end of this work, the results are ensured beneficial for the literature contribution.

Karabacak, M.; Kose, E.; Atac, A.; Sas, E. B.; Asiri, A. M.; Kurt, M.

2014-11-01

16

In Situ Synchrotron-Based IR Microspectroscopy To Study Catalytic Reactions in Zeolite Crystals  

SciTech Connect

CSI: Carbocation species identification: The nonhomogeneous distribution of the reaction products of styrene oligomerization on large ZSM-5 crystals was mapped with in situ IR microspectroscopy. Diffraction-limited spatial resolution was achieved with synchrotron light. IR spectra for possible reaction products were calculated with DFT/B3LYP; by comparison with experimental results carbocationic reaction species formed in zeolite channels could be singled out.

Stavitski,E.; Kox, M.; Swart, I.; de Groot, F.; Weckhuysen, B.

2008-01-01

17

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

18

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

19

5-Benzyl-4-[3-(1H-imidazol-1-yl)propyl]- 2H-1,2,4-triazol-3(4H)-ones: Synthesis, spectroscopic characterization, crystal structure and a comparison of theoretical and experimental IR results by DFT calculations  

NASA Astrophysics Data System (ADS)

The synthesis and structural properties of novel compounds, 5-Benzyl- 4-[3-(1H-imidazol-1-yl)propyl]-2H-1,2,4-triazol-3(4H)-ones (3a- c) have been described. These products were obtained by the reaction of ethyl 2-[1-ethoxy-2-(phenyl or substituted phenyl)ethylidene]hydrazinecarboxylates (1) and N-(3-aminopropyl)imidazol (2). The structures of compounds 3a- c have been inferred through UV-vis, IR, 1H/ 13C NMR, mass spectrometry, elemental analyses, and X-ray crystallography. DFT level 6-31G?(d,p) calculations provided structural information and IR data that were in good agreement with experimental results for compound 3a. Additionally, the electronic structure of compound 3a has been studied by DFT level 6-31G?(d,p) calculations using the X-ray data.

Ünver, Yasemin; Sancak, Kemal; Tanak, Hasan; De?irmencio?lu, ?smail; Dü?dü, Esra; Er, Mustafa; I??k, ?amil

2009-11-01

20

Synthesis of 3,4-dihydro-1,8-naphthyridin-2(1H)-ones via microwave-activated inverse electron-demand Diels-Alder reactions  

PubMed Central

Summary Substituted 3,4-dihydro-1,8-naphthyridin-2(1H)-ones have been synthesized with the inverse electron-demand Diels–Alder reaction from 1,2,4-triazines bearing an acylamino group with a terminal alkyne side chain. Alkynes were first subjected to the Sonogashira cross-coupling reaction with aryl halides, the product of which then underwent an intramolecular inverse electron-demand Diels–Alder reaction to yield 5-aryl-3,4-dihydro-1,8-naphthyridin-2(1H)-ones by an efficient synthetic route. PMID:24605148

Fadel, Salah; Hajbi, Youssef; Khouili, Mostafa; Lazar, Said

2014-01-01

21

A low-level detection system for hydrogen analysis with the reaction 1H( 15N,??) 12C  

NASA Astrophysics Data System (ADS)

A spectrometer has been constructed for measurements of low hydrogen concentrations by detecting 4.43 MeV ?-rays from the reaction 1H( 15N,??) 12C at the 6.39 MeV resonance. It consists of an annular large-volume (2600 cm 3) BGO detector, an annular plastic-detector anticoincidence shield around it, and Pb and Cd shields. The spectrometer is placed in the target hall of the laboratory located 20 m deep inside the granite bedrock. The background counting rate arising mainly from impurity of the BGO materials is 0.023 Hz in the energy range 3.9-4.9 MeV. The detection sensitivity of 10 at.ppm H in silicon substrates was determined by measurements of concentration distributions of 2 × 10 13-1 × 10 17 40 keV protons cm -2 in single-crystal silicon substrates. The range profiles of 40 keV protons simulated by molecular dynamics calculations resulted in the correction factor of 1.21 for the commonly used electronic stopping power of silicon given by Ziegler et al. [The Stopping Power and Ranges of Ions in Matter (Pergamon, New York, 1985) vol. 1].

Torri, P.; Keinonen, J.; Nordlund, K.

1994-01-01

22

BIGINELLI REACTION IN AQUEOUS MEDIUM: A GREENER AND SUSTAINABLE APPROACH TO SUBSTITUTED 3,4-DIHYDROPYRIMIDIN-2(1H)-ONES  

EPA Science Inventory

An environmentally benign aqueous Biginelli protocol for the synthesis of substituted 3,4-dihydropyrimidin-2(1H)-ones using polystyrenesulfonic acid (PSSA) as a catalyst has been achieved. These microwave-assisted reactions proceed efficiently in water in the absence of organic s...

23

Structural and Electrocatalytic Properties of PtIrCo/C Catalysts for Oxygen Reduction Reaction  

SciTech Connect

This paper describes the results of an investigation of the synthesis of PtIrCo nanoparticles (2-3 nm) for electrocatalytic oxygen reduction reaction. The carbon-supported PtIrCo catalysts (PtIrCo/C) were thermally treated at temperatures ranging from 400 to 900 C. The size, composition, and atomic-scale structures of the PtIrCo/C catalysts were characterized for establishing their correlation with the electrocatalytic activity toward oxygen reduction reaction. The specific activity was found to increase by a factor of 3-5 for the PtIrCo/C catalysts in comparison with Pt/C catalysts. A correlation was identified between the specific activity and the nanoparticle's fcc-type lattice parameter. The specific activity increases whereas the fcc-type lattice parameter decreases with the thermal treatment temperature. This correlation was further substantiated by analyzing the interatomic spatial parameters in the trimetallic nanoparticles based on X-ray absorption fine structure spectroscopic and high-energy XRD experiments. Implications of these findings, along with the durability of the catalysts, to the design of active electrocatalysts were also discussed.

Loukrakpam, Rameshwori; Wanjala, Bridgid N.; Yin, Jun; Fang, Bin; Luo, Jin; Shao, Minhua; Protsailo, Lesia; Kawamura, Tetsuo; Chen, Yongsheng; Petkov, Valeri; Zhong, Chuan-Jian (CMU); (SUNY-Binghamton); (UTC Power); (Toyota); (Penn)

2011-08-29

24

1H, 13C and 15N NMR, FT-IR as well as PM5 studies of a new Schiff base of gossypol with 3,6-dioxadecylamine in solution  

NASA Astrophysics Data System (ADS)

The Schiff base of racemic gossypol with 3,6-dioxadecylamine (GSDN) has been synthesised and its structure has been studied by FT-IR, 1H, 13C and 15N NMR spectroscopy as well as by the PM5 semiempirical method. All spectroscopic methods have provided respective evidences that GSDN in solution exists exclusively in the enamine-enamine tautomeric form. The structure of the enamine-enamine tautomer is visualized and the hydrogen bonds stabilising this structure are discussed.

Przybylski, Piotr; Lewandowska, Weronika; Brzezinski, Bogumi?; Bartl, Franz

2006-09-01

25

Ion-pair charge transfer complex with near-IR absorption: Synthesis, crystal structure and properties of [Hb] 2[Cu(mnt) 2] (Hb = 1-(4-((1H-imidazol-1-yl)methyl)benzyl)-1H-imidazol-3-ium)  

NASA Astrophysics Data System (ADS)

The compound [Hb] 2[Cu(mnt) 2] ( 1) [Hb = 1-(4-((1H-imidazol-1-yl)methyl)benzyl)-1H-imidazol-3-ium] has been synthesized, starting from 1,4-bis((1H-imidazol-1-yl)methyl)benzene, cupric chloride, and Na 2mnt in methanol. Compound 1 crystallizes in monoclinic system with C2/ c space group. In the crystal structure, the interactions between cations and anions via bifurcated C sbnd H···(NC-mnt) 2 hydrogen bonds give rise to a two dimensional supramolecular network. It has also been observed that two cation moieties (Hb) are attached together by a very short C sbnd H···N hydrogen bonding interaction with H···N distance of 1.74 Å, ?CHN bond angle of 174.9°. Compound 1 is additionally characterized by cyclic voltammetry, UV-Vis, IR, 1H NMR and EPR spectroscopy. The ion-pair compound 1 shows an intense absorption in the near-IR region at ˜1214 nm which has been described as a charge transfer band from HOMO of the copper dithiolate anion [Cu(mnt) 2] 2-, to LUMO of the [Hb] + cation. The title compound exhibits an oxidative response at +0.46 V vs. Ag/AgCl and a reductive event at -0.67 V vs. Ag/AgCl.

Kishore, Ravada; Tripuramallu, Bharat Kumar; Durgaprasad, Gummadi; Das, Samar K.

2011-03-01

26

Experimental study and nuclear model calculations on the 192Os(p,n) 192Ir reaction: Comparison of reactor and cyclotron production of the therapeutic radionuclide 192Ir  

Microsoft Academic Search

In a search for an alternative route of production of the important therapeutic radionuclide 192Ir (T1\\/2=78.83d), the excitation function of the reaction 192Os(p,n)192Ir was investigated from its threshold up to 20MeV. Thin samples of enriched 192Os were obtained by electrodeposition on Ni, and the conventional stacked-foil technique was used for cross section measurements. The experimental data were compared with the

K. Hilgers; S. Sudár; S. M. Qaim

2005-01-01

27

FT-IR and 1H NMR studies of the state of solubilized water in water-in-oil microemulsions stabilized by mixtures of single- and double-tailed cationic surfactants.  

PubMed

The structure of solubilized water in water-in-n-heptane aggregates stabilized by mixtures of single- and double-tail quaternary ammonium surfactants, namely didodecyldimethylammonium chloride/dodecyltrimethylammonium chloride (DDAC/DTAC) or didodecyldimethylammonium bromide/dodecyltrimethylammonium bromide (DDAB/DTAB) was studied by two noninvasive techniques, (1)H NMR and FT-IR. In the former, the chemical shift data, ?(obs), were used to calculate the so-called deuterium/protium fractionation factor, ?(M), of the aggregate-solubilized water and were found to be unity. In the FT-IR study, upon increasing water/surfactant molar ratio, W, the frequency, ?(OD), of the HOD species decreases, while its full width at half height and its area increase. The results obtained from both techniques indicate that the water appears to be present as a single nano-phase and the structure varies continuously as a result of increasing W. In addition, the effect of changing the counter-ion (Br(-) or Cl(-)) on (1)H NMR and FT-IR results was investigated. In spite of the known difference in the dissociation of these counter-ions from micellar aggregates, this was found not to affect the state of solubilized water. This report gives further insight into the contradictory scientific debates on the structure of water in the polar nano-cores of microemulsions. PMID:23200348

Bumajdad, Ali; Madkour, Metwally; Shaaban, Ehab; El Seoud, Omar A

2013-03-01

28

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

29

Determination of the time course of an enzymatic reaction by 1H NMR spectroscopy: hydroxynitrile lyase catalysed transhydrocyanation  

NASA Astrophysics Data System (ADS)

The time course of the enzyme catalysed transhydrocyanation of benzaldehyde to give ( S)-mandelonitrile was investigated using a hydroxynitrile lyase from Hevea brasiliensis as catalyst and acetone cyanohydrin as cyanide donor. Employing special techniques it was possible to apply 1H NMR spectroscopy in aqueous medium to monitor the concentration changes of all substrates and products. By this technique strong evidence for inhibition of the enzyme at higher substrate concentrations was obtained.

Hickel, A.; Gradnig, G.; Griengl, H.; Schall, M.; Sterk, H.

1996-01-01

30

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. PMID:24052868

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

2013-01-01

31

The complexes between Schiff base of gossypol with L-phenylalanine methyl ester and some monovalent cations studied by 1H NMR, ESI MS, FT-IR as well as PM5 semi-empirical methods  

NASA Astrophysics Data System (ADS)

The Schiff base of racemic gossypol with L-phenylalanine methyl ester and its complexes with H + and monovalent metal cations was synthesized and studied by FT-IR, 1H NMR spectroscopy and Electrospray Ionization mass spectrometry as well as by the PM5 semi-empirical method. The studied Schiff base exists in acetonitrile solution in the enamine-enamine tautomeric form. After the protonation, the tautomeric form changes into the imine-imine one. For this form of the Schiff base the existence of diastereoisomers was very well visible in the 1H NMR spectra. The structures of the protonated Schiff base and its 1:1 complex with K + cation as well as the respective hydrogen bonds within these structures are discussed.

Przybylski, Piotr; Brzezinski, Bogumil

2003-06-01

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

2013-01-01

33

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

34

Quantum mechanical and spectroscopic (FT-IR, FT-Raman, 1H NMR and UV) investigations of 2-(phenoxymethyl)benzimidazole  

NASA Astrophysics Data System (ADS)

The optimized molecular structure, vibrational frequencies, corresponding vibrational assignments of 2-(phenoxymethyl)benzimidazole have been investigated experimentally and theoretically using Gaussian09 software package. The energy and oscillator strength calculated by time dependent density functional theory results almost compliments with experimental findings. Gauge-including atomic orbital 1H NMR chemical shifts calculations were carried out and compared with experimental data. 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 has been analyzed using NBO analysis. Molecular Electrostatic Potential was performed by the DFT method and the infrared intensities and Raman activities have also been reported. Mulliken’s net charges have been calculated and compared with the atomic natural charges. First hyperpolarizability is calculated in order to find its role in non-linear optics.

Mary, Y. Shyma; Jojo, P. J.; Panicker, C. Yohannan; Van Alsenoy, Christian; Ataei, Sanaz; Yildiz, Ilkay

35

Quantum mechanical and spectroscopic (FT-IR, FT-Raman, 1H NMR and UV) investigations of 5-nitro-2-phenylbenzoxazole  

NASA Astrophysics Data System (ADS)

The optimized molecular structure, vibrational wavenumbers, corresponding vibrational assignments of 5-nitro-2-phenylbenzoxazole have been investigated experimentally and theoretically. The energy and oscillator strength calculated by Time Dependent Density Functional Theory results almost compliments with experimental findings. Gauge-including atomic orbital 1H-NMR chemical shifts calculations were carried out and compared with experimental data. The HOMO and LUMO analysis is used to determine the charge transfer with in the molecule. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis. molecular electrostatic potential was performed by the DFT method and the infrared intensities and Raman activities are also been reported. Fist hyperpolarizability is calculated in order to find its role in nonlinear optics. Antimicrobial properties indicated that the title compound possessed a broad spectrum activity against the tested Gram-positive, Gram-negative bacteria.

Bhagyasree, J. B.; Varghese, Hema Tresa; Panicker, C. Yohannan; Samuel, Jadu; Van Alsenoy, Christian; Ertan-Bolelli, Tugba; Yildiz, Ilkay

2014-04-01

36

Equilibrium and 1 H NMR Kinetic Study of the Reactions of Dichlorido [S-Methyl-L-Cysteine(N,S)]Platinum(II) Complex with Some Relevant Biomolecules  

Microsoft Academic Search

The formation equilibria of the [Pt(SMC)(H2O)2]+ complex with some biologically relevant ligands such as L-methionine (L-met) and glutathione (GSH) were studied. The stoichiometry\\u000a and stability constants of the formed complexes are reported, and the concentration distribution of the various complex species\\u000a has been evaluated as a function of pH. The reaction between [PtCl2(SMC)] and guanosine-5?-monophosphate (5?-GMP) was studied by 1H

Tanja Soldatovi?; Predrag ?anovi?; Radivoje Nikoli?; Ratomir Jeli?; Živadin D. Bugar?i?

2009-01-01

37

Characterization of 40 kDa poly(ethylene glycol) polymers by proton transfer reaction QTOF mass spectrometry and 1H-NMR spectroscopy.  

PubMed

Several electrospray mass spectrometry (ESI-MS) techniques have been described during the past years to enable the characterization work of large poly(ethylene glycol)s (PEGs) and PEGylated proteins. The proton transfer reaction ESI-MS method utilizes amines to charge reduce the electrospray envelope of PEGs, hence PEG molecules are aminated instead of protonated. This method simplifies the mass spectrum of large PEGs, and enables the interpretation of the charge state of the observable envelopes (R ? 3,000 (FWHM) measured at the (M + 6H)(6+) ion from 40 K PEG compound 7,324.19). Hence, deconvolution of the MS data can be performed and relative molecular masses of the individual chain lengths of the PEGs can be calculated. However, as the poly-dispersity of PEGs may vary from batch to batch and from sample to sample, it was of interest to examine if the method could distinguish between these kinds of different material. Therefore, sample materials of each intermediate obtained at five synthetic steps during synthesis of a 40 kDa PEG molecule were collected. These four intermediates, starting material and the target molecule were examined by (1)H-NMR spectroscopy and ESI-MS using a proton stripping base. The study revealed that the charge-stripping ESI-MS method is able to differentiate between even small changes in the structure of the polymeric molecules only when the analysis is assisted by (1)H-NMR spectroscopy. A proper characterization of polymer molecules requires besides relative molecular mass, also poly-dispersity and end-group characterization. No end-group information is obtained based on MS data. Examination of the PEG polymers by (1)H-NMR spectroscopy provides the needed information. In addition, the (1)H-NMR spectra clearly distinguishes the examined polymers. PMID:22466162

Malmstrøm, Joan

2012-05-01

38

1H NMR spectroscopic studies on the reactions of haloalkylamines with bicarbonate ions: formation of N-carbamates and 2-oxazolidones in cell culture media and blood plasma.  

PubMed

1H NMR spectroscopic methods have been applied to compare the in vitro reactivity of the renal papillary nephrotoxin 2-bromoethanamine (BEA) with those of selected halide-substituted nephrotoxic analogues, 2-chloroethanamine (CEA), 2-fluoroethanamine (FEA), and 1-phenyl-2-iodoethanamine (PIEA). The primary 1H NMR-detectable transformation during a 24 h incubation of confluent Madin Darby canine kidney (MDCK) cells with BEA, CEA, and FEA (at concentrations up to the IC50 determined by neutral red uptake) was the appearance in cell culture media of 2-oxazolidone (OX). Additional novel signals assigned as FEA carbamate (N-carbamoyl-2-fluoroethanamine) were observed in media collected following incubation of cells with FEA. We propose that N-carbamate intermediates are formed from the spontaneous reaction of these haloalkylamines with HCO(3-)-buffered growth media and that OX is formed from the carbamate via elimination of the hydrogen halide. Further 1H NMR experiments, conducted for up to 8 h at 25 degrees C on 5 mM solutions of BEA, CEA, and FEA in 2H2O containing a 20-fold excess of HCO3- at pH 7.6, demonstrated a time-dependent decrease in the concentration of the free haloalkylamines accompanied by the production of N-carbamate intermediates and OX. Under these pseudo-first-order reaction conditions, the formation of OX from BEA was complete within approximately 6 h. In similar reaction conditions OX formation from CEA (24 h after initiation) had reached 54% of its final equilibrium concentration. Equivalent experiments demonstrated that PIEA was almost completely converted to 4-phenyl-2-oxazolidinone (PHOX) within 2 h. These observations reveal the strong disposition of this series of haloalkylamines toward reaction with HCO3- and indicate that the compounds in this family may exist only transiently as free amines in vivo, where there will virtually always be excess HCO3-. The physiological relevance of the in vitro findings is further indicated by the NMR-detectable conversion of BEA to OX and also an alkylating aziridine (AZ) moiety in rat plasma containing BEA. The ability to form carbamoylated species and OX (or PHOX) may mediate the toxicity of this series of haloalkylamines and hence is potentially of considerable significance. PMID:8605287

Anthony, M L; Holmes, E; McDowell, P C; Gray, T J; Blackmore, M; Nicholson, J K

1995-12-01

39

Single crystal structure, spectroscopic (FT-IR, FT-Raman, 1H NMR, 13C NMR) studies, physico-chemical properties and theoretical calculations of 1-(4-chlorophenyl)-3-(4-nitrophenyl)triazene.  

PubMed

In this paper, we will report a combined experimental and theoretical investigation of the molecular structure and spectroscopic parameteres (FT-IR, FT-Raman, (1)H NMR, (13)C NMR) of 1-(4-chlorophenyl)-3-(4-nitrophenyl)triazene, CNT. The optimized geometry, harmonic vibrational frequencies, infrared intensities and Raman scattering activities were obtained at the B3LYP/6-311++G(d,p) level of theory and thermodynamic functions were calculated at the same level. A detailed interpretation of the Infrared, Raman and NMR spectra of the compound was reported as well. Analysis of experimental NMR chemical shifts was supported by quantum chemical calculations and HOSE code fragment based prediction tool (ACD/NMR). The theoretical results showed an excellent agreement with the experimental values. The physico-chemical properties (such as logP, hydrophobicity, …) were also calculated using three commercially available programs. PMID:22343079

Fereyduni, E; Rofouei, M K; Kamaee, M; Ramalingam, S; Sharifkhani, S M

2012-05-01

40

Spectroscopic (FT-IR, FT-Raman, 1H, 13C NMR, UV/VIS), thermogravimetric and antimicrobial studies of Ca(II), Mn(II), Cu(II), Zn(II) and Cd(II) complexes of ferulic acid.  

PubMed

The molecular structure of Mn(II), Cu(II), Zn(II), Cd(II) and Ca(II) ferulates (4-hydroxy-3-methoxycinnamates) was studied. The selected metal ferulates were synthesized. Their composition was established by means of elementary and thermogravimetric analysis. The following spectroscopic methods were used: infrared (FT-IR), Raman (FT-Raman), nuclear magnetic resonance ((13)C, (1)H NMR) and ultraviolet-visible (UV/VIS). On the basis of obtained results the electronic charge distribution in studied metal complexes in comparison with ferulic acid molecule was discussed. The microbiological study of ferulic acid and ferulates toward Escherichia coli, Bacillus subtilis, Candida albicans, Pseudomonas aeruginosa, Staphylococcus aureus and Proteus vulgaris was done. PMID:24334064

Kalinowska, M; Piekut, J; Bruss, A; Follet, C; Sienkiewicz-Gromiuk, J; ?wis?ocka, R; Rz?czy?ska, Z; Lewandowski, W

2014-03-25

41

Single crystal structure, spectroscopic (FT-IR, FT-Raman, 1H NMR, 13C NMR) studies, physico-chemical properties and theoretical calculations of 1-(4-chlorophenyl)-3-(4-nitrophenyl)triazene  

NASA Astrophysics Data System (ADS)

In this paper, we will report a combined experimental and theoretical investigation of the molecular structure and spectroscopic parameteres (FT-IR, FT-Raman, 1H NMR, 13C NMR) of 1-(4-chlorophenyl)-3-(4-nitrophenyl)triazene, CNT. The optimized geometry, harmonic vibrational frequencies, infrared intensities and Raman scattering activities were obtained at the B3LYP/6-311++G(d,p) level of theory and thermodynamic functions were calculated at the same level. A detailed interpretation of the Infrared, Raman and NMR spectra of the compound was reported as well. Analysis of experimental NMR chemical shifts was supported by quantum chemical calculations and HOSE code fragment based prediction tool (ACD/NMR). The theoretical results showed an excellent agreement with the experimental values. The physico-chemical properties (such as log P, hydrophobicity, …) were also calculated using three commercially available programs.

Fereyduni, E.; Rofouei, M. K.; Kamaee, M.; Ramalingam, S.; Sharifkhani, S. M.

2012-05-01

42

Chemical reactions between CF2HCl and NH3 induced by IR double-beam excitation  

NASA Astrophysics Data System (ADS)

Infrared multiphoton dissociation experiments with two wavelengths in different mixtures of chlorodifluoromethane and ammonia have been carried out. It is shown that the presence of ammonia in the sample induces a decrease in the chlorodifluoromethane dissociation yield. It has been observed that the distinct chemical reaction channels are differently activated as the time delay between the two laser pulses is varied. The ratio of the obtained products in the infrared multiphoton dissociation changes with the composition of the initial mixture and are not compatible with the mechanism suggested by Sugita and Arai for this reaction in single IR wavelength excitation if it is assumed to be the only contributing mechanism other than that for direct CF2HCl dissociation and subsequent C2F4 formation from the resulting CF2 radicals. It appears that, although for simultaneous two-wavelength irradiation the presence of an accumulated solid NH4Cl deposit does not significantly influence the reaction, this is no longer the case when time delays are introduced between the two beams.

Sigüenza, C. L.; Simeonov, S. A.; Díaz, L.; González-Díaz, P. F.

1993-06-01

43

Combinatorial high-throughput screening for highly active Pd-Ir-Ce based ternary catalysts in electrochemical oxygen reduction reaction.  

PubMed

A combinatorial library having 66 different ternary compositions of Pd-Ir-Ce was prepared via the impregnation method to find the optimum ternary composition with the highest performance toward oxygen reduction reaction (ORR) in acid media. Its performance in ORR activity of the combinatorial array was evaluated through two different combinatorial high-throughput screening methods to gain validity: (1) multielectrode half-cell method and (2) optical screening method. From the combinatorial results, the spot at 79:12:9 for Pd-Ir-Ce (at. %) in the array showed the highest ORR activity. The electrochemical characterizations of the single catalyst demonstrates that the optimized Pd79Ir12Ce9/C catalyst shows 1.5 times the ORR activity compared to that of Pd/C catalyst at 0.85 V (vs. RHE). In the Pd-Ir-Ce based catalysts, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) results reveal that Ir and Ce are present in the form of IrO2 and CeO2, respectively, and the electron configuration of Pd is effectively modified through the decoration with IrO2 and CeO2. From the results, we suggest that the electro-modification of Pd through strong metal-metal oxide interaction with IrO2-CeO2 was a reason for the enhanced ORR activity. PMID:24144110

Park, Sung Hyeon; Choi, Chang Hyuck; Koh, Jae Kang; Pak, Chanho; Jin, Seon-ah; Woo, Seong Ihl

2013-11-11

44

Monomeric and dimeric structures analysis and spectroscopic characterization of 3,5-difluorophenylboronic acid with experimental (FT-IR, FT-Raman, 1H and 13C NMR, UV) techniques and quantum chemical calculations  

NASA Astrophysics Data System (ADS)

The spectroscopic properties of 3,5-difluorophenylboronic acid (3,5-DFPBA, C6H3F2B(OH)2) were investigated by FT-IR, FT-Raman UV-Vis, 1H and 13C NMR spectroscopic techniques. FT-IR (4000-400 cm-1) and FT-Raman spectra (3500-10 cm-1) in the solid phase and 1H and 13C NMR spectra in DMSO solution were recorded. The UV spectra that dissolved in ethanol and water were recorded in the range of 200-400 nm for each solution. The structural and spectroscopic data of the molecule have been obtained for possible three conformers from DFT (B3LYP) with 6-311++G(d,p) basis set calculations. The geometry of the molecule was fully optimized, vibrational spectra were calculated and fundamental vibrations were assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and PQS program. Hydrogen-bonded dimer of title molecule, optimized by counterpoise correction, was also studied B3LYP at the 6-311++G(d,p) level and the effects of molecular association through O-H⋯O hydrogen bonding have been discussed. 1H and 13C NMR chemical shifts were calculated by using the gauge-invariant atomic orbital (GIAO) method. The electronic properties, such as excitation energies, oscillator strength, wavelengths, HOMO and LUMO energies, were performed by time-dependent density functional theory (TD-DFT) results complements with the experimental findings. Total and partial density of state (TDOS and PDOS) and also overlap population density of state (OPDOS) diagrams analysis were presented. The effects due to the substitutions of boric acid group and halogen were investigated. The results of the calculations were applied to simulate spectra of the title compound, which show excellent agreement with observed spectra. Besides, frontier molecular orbitals (FMO), molecular electrostatic potential (MEP), nonlinear optical properties (NLO) and thermodynamic features were performed.

Karabacak, Mehmet; Kose, Etem; Atac, Ahmet; Asiri, Abdullah M.; Kurt, Mustafa

2014-01-01

45

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

46

Pt and Ir/Al 2O 3 catalysts: Study of the impregnation reaction with new precursors  

NASA Astrophysics Data System (ADS)

The preparation of Pt or Ir/? C-Al 2O 3 reforming catalysts with K 2PtCl 6 or (NH 4) 3IrCl 6 as precursors, instead of the conventional H 2PtCl 6 or H 2IrCl 6 complexes, allows to study the influence of the acidic pretreatment of the carrier on the aqueous impregnation reaction. The quantity of adsorbed metals is in fact highly dependent on this factor. In the case of platinum catalysts, the maximum of adsorption is reached for a neutral or weakly acidic pretreatment, whereas the adsorption of iridium needs a more acidic pretreatment and corresponds to a saturation of the adsorption sites (1). This work is an Exafs investigation of these catalysts to see if some differences exist in the first coordination sphere of Pt or Ir between the conventional and our new fixation procedures.

El-Biyyadh, A.; Guerin, M.; Kappenstein, C.; Bazin, D.; Dexpert, H.

1989-06-01

47

Aza-Diels-Alder reaction between N-aryl-1-oxo-1H-isoindolium ions and tert-enamides: Steric effects on reaction outcome  

PubMed Central

Summary The synthesis of 5-substituted 6,6a-dihydroisoindolo[2,1-a]quinolin-11(5H)-ones via [4 + 2] imino-Diels–Alder cyclization from N-aryl-3-hydroxyisoindolinones and N-vinyl lactams under Lewis acid-catalysed anhydrous conditions is reported. Reactions of N-(2-substituted-aryl)-3-hydroxyisoindolinones with N-vinylpyrrolidone under identical conditions resulted in the formation of 2-(2-substitued-aryl)-3-(2-(2-oxopyrrolidin-1-yl)vinyl)isoindolin-1-one analogues indicating steric hinderance as the cause of deviation. The probable mechanism of the reaction based on the results from X-ray crystallography and molecular modelling is discussed. PMID:24778740

Chou, Ting-Yi; ALJaroudi, Zainab; Ellis, Bobby D; Cameron, T Stanley

2014-01-01

48

Aza-Diels-Alder reaction between N-aryl-1-oxo-1H-isoindolium ions and tert-enamides: Steric effects on reaction outcome.  

PubMed

The synthesis of 5-substituted 6,6a-dihydroisoindolo[2,1-a]quinolin-11(5H)-ones via [4 + 2] imino-Diels-Alder cyclization from N-aryl-3-hydroxyisoindolinones and N-vinyl lactams under Lewis acid-catalysed anhydrous conditions is reported. Reactions of N-(2-substituted-aryl)-3-hydroxyisoindolinones with N-vinylpyrrolidone under identical conditions resulted in the formation of 2-(2-substitued-aryl)-3-(2-(2-oxopyrrolidin-1-yl)vinyl)isoindolin-1-one analogues indicating steric hinderance as the cause of deviation. The probable mechanism of the reaction based on the results from X-ray crystallography and molecular modelling is discussed. PMID:24778740

Jha, Amitabh; Chou, Ting-Yi; Aljaroudi, Zainab; Ellis, Bobby D; Cameron, T Stanley

2014-01-01

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)  

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

50

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

2013-02-01

51

Quantum mechanical and spectroscopic (FT-IR, 13C, 1H NMR and UV) investigations of potent antiepileptic drug 1-(4-chloro-phenyl)-3-phenyl-succinimide  

NASA Astrophysics Data System (ADS)

This study represents an integrated approach towards understanding the vibrational, electronic, NMR, and structural aspects, and reactivity of 1-(4-chloro-phenyl)-3-phenyl-succinimide (CPPS). A detailed interpretation of the FT-IR, UV and NMR spectra were reported. The equilibrium geometry, bonding features, and harmonic vibrational frequencies have been investigated with the help of density functional theory (DFT) B3LYP method using 6-31G(d,p) and 6-311++G(d,p) basis set. The scaled theoretical wavenumber showed very good agreement with the experimental values. The 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by the Gauge-Invariant Atomic Orbital (GIAO) method. Stability of the molecule, arising from hyperconjugative interactions and charge delocalization, has been analyzed using Natural Bond Orbital (NBO) analysis. The results show that ED in the ?* and ?* antibonding orbitals and second order delocalization energies E(2) confirm the occurrence of 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 calculated by Time-Dependent DFT (TD-DFT) approach. To estimate chemical reactivity of the molecule, the molecular electrostatic potential (MEP) surface map is calculated for the optimized geometry of the molecule.

Vitnik, Vesna D.; Vitnik, Željko J.; Banjac, Nebojša R.; Valenti?, Nataša V.; Uš?umli?, Gordana S.; Jurani?, Ivan O.

2014-01-01

52

1H, 13C NMR, FT-IR, ESI MS and PM5 studies of a new 3,6,9-trioxadecylamide of monensin A and its complexes with Li +, Na + and K + cations  

NASA Astrophysics Data System (ADS)

A new 3,6,9-trioxadecylamide of monensin A (M-AM4) has been synthesised and its ability to form complexes with Li +, Na + and K + cations has been studied by ESI mass spectrometry, 1H and 13C NMR, FT-IR spectroscopy and PM5 semiempirical method. The ESI MS data indicate that M-AM4 forms complexes with Li +, Na + and K + of exclusively 1:1 stoichiometry which are stable up to cv = 70 V. The formation of the M-AM4-Na + is strongly favoured. Above cv = 70 the fragmentation process is observed. The spectroscopic studies show that the structures of the M-AM4 and its complexes with the cations of 1:1 stoichiometry are stabilized by intramolecular hydrogen bonds in which the OH groups are always involved. The C dbnd O amide group is engaged in the complexation process of each cation. The M-AM4-K + complex can also assume a structure in which the C dbnd O amide group does not participate in the complexation but the complexes of such structure do not dominate.

?owicki, Daniel; Huczy?ski, Adam; Brzezinski, Bogumil; Bartl, Franz

2011-03-01

53

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

54

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

55

Measurement of the {sup 1}H({sup 6}He,{sup 6}Li){ital n} reaction in inverse kinematics  

SciTech Connect

The {sup 1}H({sup 6}He,{sup 6}Li){ital n} reaction was studied at 0{degree} with the NSCL A1200 fragment separator in the energy loss mode. A {sup 6}He secondary beam at {ital E}/{ital A}=93 MeV was used to measure the Gamow-Teller and Fermi strengths between the ground state of {sup 6}He and the ground and excited states of {sup 6}Li, in inverse kinematics. At 0{degree} the ground-state cross section is measured to be {ital d}{sigma}{sub {ital GS}}/({ital d}{Omega})=43{plus_minus}16 mb/sr, which is dominated by systematic error in the secondary beam flux. The ratio of Gamow-Teller to Fermi strength is not sensitive to this error and is found to be (87{plus_minus}6){percent} of that expected from ({ital p},{ital n}) systematics and {beta} decay. Angular distributions have been measured between 0{degree} and 10{degree} in the center of mass. {copyright} {ital 1996 The American Physical Society.}

Brown, J.A.; Bazin, D.; Benenson, W.; Caggiano, J.; Fauerbach, M.; Hellstroem, M.; Kelley, J.H.; Kryger, R.A.; Pfaff, R.; Sherrill, B.M.; Steiner, M. [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824-1321 (United States)] [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824-1321 (United States); Morrissey, D.J.; Powell, C.F. [National Superconducting Cyclotron Laboratory and Department of Chemistry, Michigan State University, East Lansing, Michigan 48824-1321 (United States)] [National Superconducting Cyclotron Laboratory and Department of Chemistry, Michigan State University, East Lansing, Michigan 48824-1321 (United States)

1996-11-01

56

Helium diffusion coefficient measurements in R7T7 nuclear glass by 3He(d,?) 1H nuclear reaction analysis  

NASA Astrophysics Data System (ADS)

The immobilization of fission products and minor actinides by vitrification is the reference process for industrial management of high-level radioactive wastes generated by spent fuel reprocessing. Radiation damage and radiogenic helium accumulation must be specifically studied to evaluate the effects of minor actinide alpha decay on the glass long-term behavior under repository conditions. A specific experimental study was conducted for a comprehensive evaluation of the behavior of helium and its diffusion mechanisms in borosilicate nuclear waste glass. Helium production was simulated by external implantation with 3He ions at a concentration (?1 at.%) 30 times higher than obtained after 10,000 years of storage. Helium diffusion coefficients as a function of temperature were extracted from the depth profiles after annealing. The 3He(d,?) 1H nuclear reaction analysis (NRA) technique was successfully adopted for low-temperature in situ measurements of depth profiles. Its high depth resolution revealed helium mobility at temperatures as low as 253 K and the presence of a trapped helium fraction. The diffusion coefficients of un-trapped helium atoms follow an Arrhenius law between 253 K and 323 K. An activation energy of 0.55 ± 0.03 eV was determined, which is consistent with a process controlled by diffusion in the glass free volume.

Chamssedine, F.; Sauvage, T.; Peuget, S.; Fares, T.; Martin, G.

2010-05-01

57

Free radicals formed in the reaction of 1H-1-oxo-2,4,6,8-tetrakis-(tert-butyl)phenoxazine and 1-hydroxy-2,4,6,8-tetrakis(tert-butyl)-phenoxazinyl radical with certain organometallic compounds  

SciTech Connect

1H-1-Oxo-2,4,6,8-tetrakis(tert-butyl)phenoxazine undergoes ligand exchange reactions and behaves as a spin trap for metal-centered radicals, as a result of which stable paramagnetic complexes are formed with delocalization of the unpaired electron in the organic ligand. Paramagnetic complexes are also formed as the result of a reaction between potassium salt (IA) and triphenyl-tin and triphenyl-lead monochlorides.

Karsanov, I.V.; Ivakhnenko, E.P.; Khandkarova, V.S.; Rubezhov, A.Z.; Okhlobystin, O.Yu.; Minkin, V.I.; Prokof'ev, A.I.; Kabachnik, M.I.

1987-07-10

58

Preignition reactions of AP-HTPB propellants studied by IR spectrometry. [Ammonium Perchlorate-Hydroxyl Terminated PolyButadiene  

NASA Technical Reports Server (NTRS)

IR absorption spectrometry was used to follow the disappearance of NH and CH bonds during the pyrolysis of a polymer film containing 30 weight percent ammonium perchlorate (AP). The remaining 70 weight percent consisted of a mixture of 92.5 weight percent hydroxyl-terminated polybutadiene (HTPB) and 7.5 weight percent isophrone diisocyanate (IPDI). The results indicate that polymer decomposition is induced by products of AP decomposition, and that about 2.5 CH bonds disappear for each NH bond that disappears. The diffusion process occurring in the later stages of the reaction is analyzed in an attempt to account for the unexpectedly low activation energy.

Law, R. J.; Baer, A. D.; Ryan, N. W.

1977-01-01

59

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

60

13 C and 1 H NMR spectra and stereoconfiguration of 1,4-adducts of the Diels-Alder reaction of furan with methyl acrylate and maleic anhydride  

Microsoft Academic Search

13C and1H NMR spectra were taken for the 1,4-adducts of furan with methyl acrylate and maleic anhydride. The13C chemical shifts are characteristic: these values for C1, C3, and C6 (adducts (I) and (II)) and C1, C4 C2, C3, C5, and C6 (adducts (III) and (IV)) depend on the orientation of the substituent at C2 in the case of methyl acrylate

Vo So Bogdanov; M. V. Kel'tseva; V. M. Zhulin

1990-01-01

61

Reactions in Nitroimidazole Triggered by Low-Energy (0-2?eV) Electrons: Methylation at N1-H Completely Blocks Reactivity.  

PubMed

Low-energy electrons (LEEs) at energies of less than 2?eV effectively decompose 4-nitroimidazole (4NI) by dissociative electron attachment (DEA). The reactions include simple bond cleavages but also complex reactions involving multiple bond cleavages and formation of new molecules. Both simple and complex reactions are associated with pronounced sharp features in the anionic yields, which are interpreted as vibrational Feshbach resonances acting as effective doorways for DEA. The remarkably rich chemistry of 4NI is completely blocked in 1-methyl-4-nitroimidazole (Me4NI), that is, upon methylation of 4NI at the N1 site. These remarkable results have also implications for the development of nitroimidazole based radiosensitizers in tumor radiation therapy. PMID:25224248

Tanzer, Katrin; Feketeová, Linda; Puschnigg, Benjamin; Scheier, Paul; Illenberger, Eugen; Denifl, Stephan

2014-11-01

62

Three ways of reactions of 5-(3,5-dimethyl-1 H -pyrazol-1-yl)-2-phenyl-1,3-oxazole-4-carbonitrile and its analogs with nitrogen-containing bases  

Microsoft Academic Search

Substituted 5-(3,5-dimethyl-1H-pyrazol-1-yl)-1,3-oxazole-4-carbonitrile differently react with nitrogen bases having different numbers of labile hydrogen\\u000a atoms. Treatment of the title compounds with secondary amines or morpholine results in nucleophilic replacement of the pyrazolyl\\u000a substituent at C5, the ozaxole ring remaining unchanged. Their reactions with primary amines are accompanied by cleavage of the oxazole ring\\u000a with formation of the corresponding enamino nitriles. Hydrazine

O. V. Shablykin; V. S. Brovarets; E. B. Rusanov; B. S. Drach

2008-01-01

63

Reaction of 1H-1-oxo-2,4,6,8-tetrakis(tert-butyl)phenoxazine with certain group II-IV metals  

SciTech Connect

It has already been shown that 2-amino-4,6-di(tert-butyl)phenol reacts with 3,5-di(tert-butyl)-o-benzoquinone to form 1H-1-oxo-2,4,6,8-tetrakis(tert-butyl)phenoxazine (I), which is readily reduced by alkali metals to the corresponding semiquinone anion-radical (II), and further to the diamagnetic dianion (IIA). They made use of this ability of (I) to undergo reduction to prepare anion-radical salts with different group II-IV metals in the form of their amalgams. In the EPR spectrum of the anion-radical complex (III) formed in the reduction of (I) by a thallium amalgam, the HFI constants of the unpaired electron with magnetic nuclei of the organic ligand are close to those of the K-salt (II), and a substantial HFI is observed with the /sup 203,205/Tl nuclei. This unequivocally proves that the complex has a semiquinone structure, since an HFI on the /sup 203,205/Tl nuclei of such an order of magnitude is characteristic of o-benzoquinone salts with a thallium cation.

Karsanov, I.V.; Ivakhnenko, E.P.; Khandkarova, V.S.; Rubezhov, A.Z.; Okhlobystin, O.Yu.; Minkin, V.I.; Prokof'ev, A.I.; Kabachnik, M.I.

1987-07-10

64

IR Characterization of BiPropellant Reaction Control Engines During Auxiliary Propulsion Systems Tests at NASA's White Sands Test Facility In Las Cruces, New Mexico  

Microsoft Academic Search

This paper describes the application of a FLIR Systems A40M infrared (IR) digital camera for thermal monitoring of a Liquid Oxygen (LOX) and Ethanol bi-propellant Reaction Control Engine (RCE) during Auxiliary Propulsion System (APS) testing at the National Aeronautics & Space Administration's (NASA) White Sands Test Facility (WSTF) near Las Cruces, New Mexico. Typically, NASA has relied mostly on the

Elizabeth Holleman

65

Palladium-catalysed cross-coupling reaction of ultra-stabilised 2-aryl-1,3-dihydro-1H-benzo[d]1,3,2-diazaborole compounds with aryl bromides: A direct protocol for the preparation of unsymmetrical biaryls  

PubMed Central

Summary There has been a significant interest in organoboron compounds such as arylboronic acids, arylboronate esters and potassium aryltrifluoroborate salts because they are versatile coupling partners in metal-catalysed cross-coupling reactions. On the other hand, their nitrogen analogues, namely, 1,3,2-benzodiazaborole-type compounds have been studied extensively for their intriguing absorption and fluorescence characteristics. Here we describe the first palladium-catalysed Suzuki–Miyaura cross-coupling reaction of easily accessible and ultra-stabilised 2-aryl-1,3-dihydro-1H-benzo[d]1,3,2-diazaborole derivatives with various aryl bromides. Aryl bromides bearing electron-withdrawing, electron-neutral and electron-donating substituents are reacted under the catalytic system furnishing unsymmetrical biaryl products in isolated yields of up to 96% in only 10 minutes. PMID:24991260

Sithebe, Siphamandla

2014-01-01

66

/sup 1/H NMR study of the base-pairing reactions of d(GGAATTCC): salt and polyamine effects on the imino proton exchange  

SciTech Connect

Salts and polyamines have a variety of effects on the physical properties of DNA, including stabilization against thermal melting. The authors wished to gain greater insight into the mechanism of this stabilization by ascertaining its effect on the dynamics of base opening and closing reactions, as measured by NMR. Since the binding of spermidine (3+) is influenced by salt, and since spermidine may act as a base catalyst in proton exchange reactions, they have undertaken a study of salt and base catalyst effects on the imino proton exchange kinetics of a model oligomeric DNA. The selective longitudinal NMR relaxation rates of the hydrogen-bonded imino protons of the self-complementary octadeoxyribonucleotide d(GGAATTCC) monitor the rate of the base-catalyzed chemical exchange of these protons with solvent water. The exchange rates thus obtained provide a sensitive measure of the base-pair opening reactions of the DNA duplex. Under conditions of low pH and no added base catalyst, the NMR relaxation rates allow the determination of k/sub d/, the rate constant for the dissociation of the octameric duplex into single strands. Titration with the base catalyst tris(hydroxymethyl) aminomethane allows the determination of k/sub op/, the rate constant for the localized opening of individual base pairs, prior to dissociation. The activation energy for helix dissociation is not dependent on the sodium ion concentration. In agreement with previous results, no measurable salt dependence is found for k/sub op/. Under low-salt conditions, the trivalent cation spermidine decreases the rate of helix dissociation, again without affecting the activation energy for this process.

Braunlin, W.H.; Bloomfield, V.A.

1988-02-23

67

Capture and dissociation in the complex-forming CH(v = 0,1) + D2 ? CHD + D, CD2 + H, CD + HD reactions and comparison with CH(v = 0,1) + H2.  

PubMed

Rate coefficients for the CH(v = 0,1) + D(2) reaction have been determined for all possible channels (T: 200-1200 K), using the quasiclassical trajectory method and a suitable treatment of the zero point energy. Calculations have also been performed on the CH(v = 1) + H(2) reaction and the CH(v = 1) + D(2) ? CH(v = 0) + D(2) process. Most of the results can be understood considering the key role played by the deep minimum of the potential energy surface (PES), the barrierless character of the PES, the energy of the reaction channels, and the kinematics. The good agreement found between theory and experiment for the rate coefficients of the capture process of CH(v = 0) + D(2), the total reactivity of CH(v = 1) + D(2), H(2), as well as the good agreement observed for the related CH(v = 0) + H(2) system (capture and abstraction), gives confidence on the theoretical rate coefficients obtained for the capture processes of CH(v = 1) + D(2), H(2), the individual reactive processes of CH(v = 1) + D(2), H(2), the abstraction and abstraction-exchange reactions for CH(v = 0) + D(2), and the inelastic process mentioned above, for which there are no experimental data available, and that can be useful in combustion chemistry and astrochemistry. PMID:21698329

González, Miguel; Mayneris-Perxachs, Jordi; Saracibar, Amaia; Garcia, Ernesto

2011-08-14

68

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

69

Comparative IR study of nitric oxide reactions with sublimed layers of iron(II)- and ruthenium(II)-meso-tetraphenylporphyrinates.  

PubMed

The interactions of nitric oxide gas with thin layers of Fe(II)(TPP) and Ru(II)(TPP), obtained by sublimation onto low-temperature substrate (77 K), has been investigated by means of IR spectroscopy (TPP = meso-tetraphenylporphyrinate). Only simple addition of NO to form Fe(TPP)(NO) is observed for the iron-porphyrin Fe(II)(TPP), while, in contrast, Ru(II)(TPP) promotes NO disproportionation to form the nitrosyl-nitrito complex Ru(TPP)(NO)(ONO) and N(2)O. Thin layers of Fe(TPP)(NO) are inert to further reaction with excess NO; however, the nitrosyl-nitro complex Fe(TPP)(NO)(NO(2)) is readily formed when traces of dioxygen are added to the NO atmosphere. When the NO(2) concentrations in the NO/NO(2) mixture are relatively high, the nitrato complex Fe(TPP)(NO(3)) is also formed. Spectral data are given indicating that moderate shifts in the nitrosyl stretching frequency of Fe(TPP)(NO) are due to crystal packing effects, rather than to the H-bonding of coordinated NO with protic contaminants suggested in an earlier publication. Removal of NO by exhaustive evacuation from layers containing Fe(TPP)(NO)(NO(2)) leads to formation of Fe(TPP)(NO) and Fe(TPP)(NO(3)). PMID:12188676

Kurtikyan, Tigran S; Martirosyan, Garik G; Lorkovic', Ivan M; Ford, Peter C

2002-08-28

70

Formation of condensed 1H-pyrrol-2-ylphosphonates and 1,2-dihydropyridin-2-ylphosphonates via Kabachnik-Fields reaction of acetylenic aldehydes and subsequent 5-exo-dig or 6-endo-dig cyclizations.  

PubMed

Kabachnik-Fields reactions of various carbocyclic or heterocyclic acetylenic aldehydes together with subsequent Lewis acid catalyzed cyclizations have been studied. It was found that 5-exo-dig versus 6-endo-dig cyclization mode strongly depends on the structure of starting materials. Thus, nonaromatic acetylenic ?-anilinomethylphosphonates underwent gold(III)-catalyzed or iodine-mediated 5-exo-dig cyclization to 1H-pyrrol-2-ylphosphonates. In contrast, electron-withdrawing heteroaromatic substrates formed 1,2-dihydropyridin-2-ylphosphonate ring containing materials via an exclusive 6-endo-dig ring-closure process. The dual mode of cyclization is possible only for ?-amino (2-alkynylphenyl)methylphosphonates containing a benzene ring. PMID:24956009

Bukšnaitien?, Rita; Urbanait?, Aurelija; ?ikotien?, Inga

2014-07-18

71

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

72

Influence of the preparation method on the morphological and electrochemical properties of Ti\\/IrO 2-coated electrodes  

Microsoft Academic Search

The IrO2 layer deposited on a Ti substrate for electrocatalysis of the oxygen evolution reaction (OER) in acidic media was obtained from one of three different deposition methods consisting of painting the substrate with the corresponding solutions followed by heat treatment at a temperature range 400–600°C for 1 h. The coating solutions were prepared by dissolving IrCl3?·?3H2O in 15% HCl

A de Oliveira-Sousa; M. A. S da Silva; S. A. S Machado; L. A Avaca; P de Lima-Neto

2000-01-01

73

Cross sections and tensor analyzing powers A_yy of the reaction ^1H(|vec|d,pp)n in SCRE geometries at E_d=19 MeV  

SciTech Connect

We measured the cross sections and tensor analyzing powers of the 1H({approx}d,pp)n breakup reaction at Ed=19 MeV in four symmetric constant relative energy (SCRE) configurations. The data are compared with theoretical predictions from three different approaches: one based on high precision (semi)phenomenological potentials alone or combined with model three-nucleon forces, another on chiral forces up to next-to-next-to-leading order (NNLO) in the chiral expansion. In both cases, the Coulomb interaction is not included. In addition, a comparison to predictions based on CD Bonn including the Lambda excitation and the Coulomb force is presented. In all cases the measured cross sections are significantly below the theoretical values whereas the magnitude of the tensor analyzing powers agree within the error bars in three of the four cases. The apparent discrepancies in the breakup cross sections are similar to the known differences for the space-star breakup. This adds to the data base of unsolved low-energy discrepancies.

J. Ley; C. Dueweke; A. Emmerich; A. Imig; H. Paez gen. Schieck; J. Golak; H. Witala; Evgeny Epelbaum; A. Deltuva; A. C. Fonseca; W. Gloeckle; Ulf-G. Meissner; A. Nogga; P. U. Sauer

2006-02-01

74

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.  

SciTech Connect

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 W=1.95 and 2.22 GeV. The measured cross sections were separated into the four structure functions sigmaL,sigmaT,sigmaLT, and sigmaTT. 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 Q2 are presented. Some global featu

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

2008-10-01

75

U1h Superstructure  

SciTech Connect

The U1H Shaft Project is a design build subcontract to supply the U. S. Department of Energy (DOE) a 1,045 ft. deep, 20 ft. diameter, concrete lined shaft for unspecified purposes. The subcontract awarded to Atkinson Construction by Bechtel Nevada to design and construct the shaft for the DOE has been split into phases with portions of the work being released as dictated by available funding. The first portion released included the design for the shaft, permanent hoist, headframe, and collar arrangement. The second release consisted of constructing the shaft collar to a depth of 110 ft., the service entry, utility trenches, and installation of the temporary sinking plant. The temporary sinking plant included the installation of the sinking headframe, the sinking hoist, two deck winches, the shaft form, the sinking work deck, and temporary utilities required to sink the shaft. Both the design and collar construction were completed on schedule. The third release consisted of excavating and lining the shaft to the station depth of approximately 950 feet. Work is currently proceeding on this production sinking phase. At a depth of approximately 600 feet, Atkinson has surpassed production expectation and is more than 3 months ahead of schedule. Atkinson has employed the use of a Bobcat 331 excavator as the primary means of excavation. the shaft is being excavated entirely in an alluvial deposit with varying degrees of calcium carbonate cementation. Several more work packages are expected to be released in the near future. The remaining work packages include, construction of the shaft station a depth of 975 ft. and construction of the shaft sump to a depth of 1,045 ft., installation of the loading pocket and station steel and equipment, installation of the shaft steel and guides, installation of the shaft utilities, and installation of the permanent headframe, hoist, collar utilities, and facilities.

Glen Sykes

2000-11-01

76

Acknowledgement Determination of the authenticity of commercial coffees using 1H  

E-print Network

Acknowledgement ! " Determination of the authenticity of commercial coffees using 1H NMR, FT-IR spectra and chemometrics Determination of the authenticity of commercial coffees usingDetermination of the authenticity of commercial coffees using 11 HH NMR, FT-IR spectra andNMR, FT-IR spectra

Ferreira, Márcia M. C.

77

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

78

On the faradaic selectivity and the role of surface inhomogeneity during the chlorine evolution reaction on ternary Ti-Ru-Ir mixed metal oxide electrocatalysts.  

PubMed

The faradaic selectivity of the chlorine evolution reaction (CER) and oxygen evolution reaction (OER) on the industrially important Ti-Ru-Ir mixed metal oxide is discussed. Absolute evolution rates as well as volume fractions of Cl2 and O2 were quantified using differential electrochemical mass spectrometry (DEMS), while the catalyst surface redox behavior was analyzed using cyclic voltammetry. The spatial inhomogeneity of the surface catalytic reaction rate was probed using Scanning Electrochemical Microscopy (SECM). Although the nature of the competition between electrochemical discharging of chloride ions and water molecules remains elusive on a molecular scale, new insights into the spatial reactivity distribution of the CER and OER were obtained. Oxidation of water is the initial step in corrosion and concomitant deactivation of the oxide electrodes; however, at the same time the nature of interaction between the oxide surface and water is used as a rational indicator of selectivity and catalytic activity. An experimental procedure was established that would allow the study of selectivity of a variety of different catalyst materials using polycrystalline electrode surfaces. PMID:24752521

Zeradjanin, Aleksandar R; Menzel, Nadine; Schuhmann, Wolfgang; Strasser, Peter

2014-07-21

79

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. PMID:8994615

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

1997-01-01

80

Measurement of the partial cross sections ?[subscript TT], ?[subscript LT], and (?[subscript T] + ??[subscript L]) of the [superscript 1]H(e, e??[subscript +])n reaction in the ?(1232) resonance  

E-print Network

We report precision [superscript 1]H(e, e??[superscript +])n measurements in the ?(1232) resonance at Q[superscript 2]=0.127(GeV/c)[superscript 2] obtained at the MIT-Bates out-of-plane scattering facility. These are the ...

Nakagawa, I.

81

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

NASA Astrophysics Data System (ADS)

The ring-retaining products of the OH-initiated degradation of phenol and o-, m-, and p-cresol in the presence of NO x have been investigated and their formation yields determined. The experiments were carried out in a large volume reactor at (298±2) K and 1000 mbar total pressure of synthetic air using FT-IR spectroscopy for the analysis of reactants and products. The products observed and their respective molar yields were: from phenol: 1,2-dihydroxybenzene (80.4±12.1)%, 1,4-benzoquinone (3.7±1.2)% and 2-nitrophenol (5.8±1.0)%; from o-cresol: 3-methyl-1,2-dihydroxybenzene (73.4±14.6)%, methyl-1,4-benzoquinone (6.8±1.0)% and 6-methyl-2-nitrophenol (6.8±1.5)%; from m-cresol: 3-methyl-1,2-dihydroxybenzene (68.6±13.4)%, 4-methyl-1,2-dihydroxybenzene (9.7±2.7)%, methyl-1,4-benzoquinone (11.3±2.5)%, 5-methyl-2-nitrophenol (4.4±1.5)% and 3-methyl-2-nitrophenol (4.3±1.6)% and from p-cresol: 4-methyl-1,2-dihydroxybenzene (64.1±11.3)% and 4-methyl-2-nitrophenol (7.6±2.2)%. Reaction pathways leading to the observed products are proposed and potential ramifications for the atmospheric reaction mechanisms of aromatic hydrocarbons are considered.

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

82

Density functional theory (DFT) and natural bond orbital (NBO) investigation of intramolecular hydrogen bond interaction and excited-state intramolecular proton transfer (ESIPT) reaction in a five-membered hydrogen-bonding system 2-(1 H-pyrazol-5-yl)pyridine: On the possibility of solvent (water)-assisted ESPT  

Microsoft Academic Search

The present work aims at exploring the excited-state intramolecular proton transfer (ESIPT) reaction in a five-member hydrogen bonding ring system, viz., 2-(1H-pyrazol-5-yl)pyridine (2Pz–5Py), in which the ESIPT process is found to be associated with an appreciably large barrier, on the lexicon of a Density Functional Theory (DFT)-based computational approach. Nevertheless the feasibility of ESIPT has been argued from the changeover

Bijan Kumar Paul; Nikhil Guchhait

2011-01-01

83

Linear metal-metal-bonded tetranuclear M-Mo-Mo-M complexes (M = Ir and Rh): oxidative metal-metal bond formation in a tetrametallic system and 1,4-addition reaction of alkyl halides.  

PubMed

Reaction of Mo2(pyphos)4 (1) with [MCl(CO)2]2 (M = Ir and Rh) afforded linear tetranuclear complexes of a formula Mo2M2(CO)2(Cl)2(pyphos)4 (2, M = Ir; 3, M = Rh). X-ray diffraction studies confirmed that two "MCl(CO)" fragments are introduced into both axial sites of the Mo2 core in 1 and coordinated by two PPh2 groups in a trans fashion, thereby forming a square-planar geometry around each M(I) metal. Treatment of 2 and 3 with an excess amount of tBuNC and XylNC induced dissociation of the carbonyl and chloride ligands to yield the corresponding dicationic complexes [Mo2M2(pyphos)4(tBuNC)4](Cl)2 (5a, M = Ir; 6a, M = Rh) and [Mo2M2(pyphos)4(XylNC)4](Cl)2 (7, M = Ir; 8, M = Rh). Their molecular structures were characterized by spectroscopic data as well as X-ray diffraction studies of BPh4 derivatives [Mo2M2(pyphos)4(tBuNC)4](BPh4)2 (5b, M = Ir; 6c, M = Rh), which confirmed that there is no direct sigma-bonding interaction between the M(I) atom and the Mo2 core. The M(I) atom in 5 and 6 can be oxidized by either 2 equiv of [Cp2Fe][PF6] or an equimolar amount of I2 to afford Mo(II)2M(II)2 complexes, [Mo2M2(X)2(tBuNC)4(pyphos)4]2+ in which two Mo-M(II) single bonds are formed and the bond order of the Mo-Mo moiety has been decreased to three. The Ir(I) complex 5a reacted not only with methyl iodide but also with dichloromethane to afford the 1,4-oxidative addition products [Mo2Ir2(CH3)(I)(tBuNC)4(pyphos)4](Cl)2 (13) and [Mo2Ir2(CH2Cl)(Cl)(tBuNC)4(pyphos)4](Cl)2 (15), respectively, although the corresponding reactions using the Rh(I) analogue 6 did not proceed. Kinetic analysis of the reaction with CH3I suggested that the 1,4-oxidative addition to the Ir(I) complex occurs in an SN2 reaction mechanism. PMID:17608413

Ohashi, Masato; Shima, Asuka; Rüffer, Tobias; Mizomoto, Hitoshi; Kaneda, Yutaka; Mashima, Kazushi

2007-08-01

84

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

85

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

86

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

2013-02-28

87

Two new neutral copper(II) complexes with dipicolinic acid and 3-amino-1H-1,2,4-triazole formed under different reaction conditions: synthesis, characterization, molecular structures and DNA-binding studies.  

PubMed

Two Cu(II) complexes, [Cu?(?-atr)(pydc)?(H?O)?]·5H?O (1) and [Cu(atr)(pydc) (H?O)]·H?O (2), with pyridine-2,6-dicarboxylic acid (H?pydc) and 3-amino-1H-1,2,4-triazole (atr), have been synthesized and characterized. The interaction ability of the both complexes with native calf thymus DNA (CT-DNA) has been monitored as a function of the metal complex-DNA molar ratio. UV-vis spectrophotometry, circular dichroism (CD), thermal denaturation studies, cyclic voltammetry (CV) and viscosity measurements. The intrinsic binding constants K(b) of complexes 1 and 2, with CT-DNA obtained from UV-vis absorption studies were 4.7 (±0. 1) × 10(4) and 9.5 (±0. 1) × 10(4) M(-1), respectively. Further investigation of interaction mode was performed using viscosity, cyclic voltammetry and T(m) of CT-DNA studies as well as CD study, indicating complexes bind to DNA via an intercalation mode. PMID:24177363

Tabatabaee, Masoumeh; Bordbar, Maryam; Ghassemzadeh, Mitra; Tahriri, Mozhgan; Tahrir, Marjan; Mehri Lighvan, Zohreh; Neumüller, Bernhard

2013-01-01

88

Preparation, GIAO NMR calculations and acidic properties of some novel 4,5-dihydro-1H-1,2,4-triazol-5-one derivatives with their antioxidant activities.  

PubMed

Six novel 3-alkyl(aryl)-4-(p-nitrobenzoylamino)-4,5-dihydro-1H-1,2,4-triazol-5- ones (2a-f) were synthesized by the reactions of 3-alkyl(aryl)-4-amino-4,5-dihydro-1H- 1,2,4-triazol-5-ones (1a-f) with p-nitrobenzoyl chloride and characterized by elemental analyses and IR, (1)H-NMR, (13)C-NMR and UV spectral data. The newly synthesized compounds 2 were titrated potentiometrically with tetrabutylammonium hydroxide in four non-aqueous solvents such as acetone, isopropyl alcohol, tert-butyl alcohol and N,N-dimethylformamide, and the half-neutralization potential values and the corresponding pK(a) values were determined for all cases. Thus, the effects of solvents and molecular structure upon acidity were investigated. In addition, isotropic (1)H and (13)C nuclear magnetic shielding constants of compounds 2 were obtained by the gauge-including-atomic-orbital (GIAO) method at the B3LYP density functional level. The geometry of each compound has been optimized using the 6-311G basis set. Theoretical values were compared to the experimental data. Furthermore, these new compounds and five recently reported 3-alkyl-4-(2-furoylamino)-4,5-dihydro-1H-1,2,4-triazol-5-ones (3a-c,e,f) were screened for their antioxidant activities. PMID:19325716

Yüksek, Haydar; Alkan, Muzaffer; Cakmak, Ismail; Ocak, Zafer; Bahçeci, Sule; Calapo?lu, Mustafa; Elmasta?, Mahfuz; Kolomuç, Ali; Aksu, Havva

2008-01-01

89

Solvent-free Michael addition reaction of fluorene with chalcon  

Microsoft Academic Search

A series of novel Michael addition products of fluorene to chalcone were obtained in the presence of sodium hydroxide under solvent-free condition. The advantages of this procedure were mild reaction conditions, simple protocol, and high yields. The structures of the products were characterized by IR, 1H NMR, MS and X-ray diffraction. The crystal of the new compound 3h is Triclinic,

Fu Feng

2011-01-01

90

Synthesis, characterization and theoretical studies of 5-(benzylthio)-1-cylopentyl-1H-tetrazole.  

PubMed

In this study, 5-(benzylthio)-1-cylopentyl-1H-tetrazole (5B1C1HT) have been synthesized. Boiling points of the obtained compound have been determined and it has been characterized by FT-IR, (1)H NMR, (13)C-APT and LC-MS spectroscopy techniques. The FT-IR, (1)H NMR and (13)C-APT spectral measurements of the 5B1C1HT compound and complete assignment of the vibrational bands observed in spectra has been discussed. The spectra were interpreted with the aid of normal coordinate analysis following full structure optimization and force field calculations based on Density Functional Theory (DFT) at 6-311++G(**), cc-pVDZ and cc-pVTZ basis sets. The optimized geometry with 6-311++G(**) basis sets were used to determine the total energy distribution, harmonic vibrational frequencies, IR intensities. PMID:25171051

Saglam, S; Disli, A; Erdogdu, Y; Marchewka, M K; Kanagathara, N; Bay, B; Güllüo?lu, M T

2015-01-25

91

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

92

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

PubMed

A series of novel 1-ferrocenyl-2-(3-phenyl-1H-1,2,4-triazol-5-ylthio)ethanone derivatives was synthesized by the reaction of 3-substituted-1H-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 (1)H 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 500nm and maximal emission bands are about 566nm. The intensity of fluorescence and maximal emission bands are dependent on the groups bonded to triazole rings. PMID:20452271

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

2010-09-01

93

Experimental study of the A(e,e 'pi(+)) [A (e, e prime pi superscript +)] reaction on H-1 [superscript 1 H], H-2 [superscript 2 H], C-12 [superscript 12 C], Al-27 [superscript 27 Al], Cu-63 [superscript 63 Cu], and Au-197 [superscript 197 Au  

E-print Network

Cross sections for the 1H(e,e??+)n [superscript 1 H (e, e prime pi superscript +) n] process on 1H [superscript 1 H], 2H [superscript 2 H], 12C [superscript 12 C], 27Al [superscript 27 Al], 63Cu [superscript 63 Cu], and ...

Clasie, Benjamin Michael Patrick

94

IR SensorsIR Sensors IR Sensor ApplicationsIR Sensor Applications  

E-print Network

IR SensorsIR Sensors #12;IR Sensor ApplicationsIR Sensor Applications Security/Motion Detector Types of IR SensorsTwo Types of IR Sensors TransmissiveTransmissive ­­ Emitter andEmitter and Detector faceDetector face one anotherone another ReflectiveReflective ­­ Emitter reflectsEmitter reflects IR

La Rosa, Andres H.

95

Poly(ethylene glycol) (PEG-400) as an alternative reaction solvent for the synthesis of some new 1-(4-(4'-chlorophenyl)-2-thiazolyl)-3-aryl-5-(2-butyl-4-chloro-1H-imidazol-5yl)-2-pyrazolines and their in vitro antimicrobial evaluation.  

PubMed

Several 1-(4-(4'-chlorophenyl)-2-thiazolyl)-3-aryl-5-(2-butyl-4-chloro-1H-imidazol-5yl)-2-pyrazoline derivatives were prepared by the base catalyzed treatment of appropriate chalcones with 4-(4'-chlorophenyl)-2-hydrazino-thiazole in poly (ethylene glycol) (PEG-400) as an alternative reaction solvent. All the synthesized compounds were tested for their antimicrobial activities against Escherichia coli (MTCC 2939), Salmonella typhi (MTCC 98), Staphylococcus aureus (MTCC 96), Bacillus subtilis (MTCC 441), Aspergillus niger (MTCC 281), Trichoderma viridae (MTCC 167), Penicillium chrysogenum (MTCC 160), Fusarium moniliforme (MTCC 156) and Candida albicans (MTCC 183). Most of the compounds showed potent antibacterial and antifungal activity. PMID:19896247

Dawane, Bhaskar S; Konda, Shankaraiah G; Mandawad, Gajanan G; Shaikh, Baseer M

2010-01-01

96

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

97

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

98

Radical coupling for directed C-C/C-S bond formation in the reaction of Cp*IrS2C2B10H10 with 1-azido-3-nitrobenzene.  

PubMed

Reactions of half-sandwich complex Cp*IrS2C2B10H10 (1) with 1-azido-3-nitrobenzene (3-NO2C6H4N3, L) upon heating or under light led to new complexes 2-6. Complexes 2 and 3 contain a five-membered cyclometalated ligand arising from C(sp(2))-H activation of the azide ligand L. Complex 4 is a 16 electron species containing a new-generated C-C bond between the azide ligand L and the Cp* unit where C(sp(3))-H activation of the methyl unit occurred. Complexes 5 and 6 contain two types of the ligand which appear in complexes 2, 3 and 4. Further reactions of complexes 5 and 6 with L under more harsh conditions gave rise to the nucleophilic addition products 7 and 8, where ring expansion of the azide ligand at the imido site of complexes 5 and 6 happened. Complexes 2-8 were characterized by NMR, MS, IR, and elemental analysis, and X-ray structural analyses were performed for complexes 2-4 and 6-8. The radical mechanisms for the formation of complexes 2-6 were proposed on the basis of capture experiments by EPR and ESI-MS. And the formation mechanism of complexes 7 and 8 was also suggested. PMID:24108087

Zhong, Wei; Jiang, Qibai; Zhang, Qian; Shang, Yi; Yan, Hong; Bregadze, Vladimir

2014-04-01

99

FT-IR, FT-Raman, molecular structure, first order hyperpolarizability, HOMO and LUMO analysis, MEP and NBO analysis of 3-(adamantan-1-yl)-4-(prop-2-en-1-yl)-1H-1,2,4-triazole-5(4H)-thione, a potential bioactive agent.  

PubMed

The optimized molecular structure, vibrational frequencies, corresponding vibrational assignments of 3-(adamantan-1-yl)-4-(prop-2-en-1-yl)-1H-1,2,4-triazole-5(4H)-thione have been investigated experimentally and theoretically using Gaussian09 software package. Potential energy distribution of normal modes vibrations was done using GAR2PED program. The HOMO and LUMO analysis are used to determine the charge transfer within the molecule. The stability of the molecule arising from hyperconjugative interaction and charge delocalization has been analyzed using NBO analysis. The calculated geometrical parameters are in agreement with the XRD data. The calculated first hyperpolarizability is high and the title compound is an attractive candidate for further studies in nonlinear optical applications. To estimate the chemical reactivity of the molecule, the molecular electrostatic potential is calculated for the optimized geometry of the molecule. PMID:24878436

Rosline Sebastian, S H; Attia, Mohamed I; Almutairi, Maha S; El-Emam, Ali A; Panicker, C Yohannan; Van Alsenoy, Christian

2014-11-11

100

FT-IR, FT-Raman, molecular structure, first order hyperpolarizability, HOMO and LUMO analysis, MEP and NBO analysis of 3-(adamantan-1-yl)-4-(prop-2-en-1-yl)-1H-1,2,4-triazole-5(4H)-thione, a potential bioactive agent  

NASA Astrophysics Data System (ADS)

The optimized molecular structure, vibrational frequencies, corresponding vibrational assignments of 3-(adamantan-1-yl)-4-(prop-2-en-1-yl)-1H-1,2,4-triazole-5(4H)-thione have been investigated experimentally and theoretically using Gaussian09 software package. Potential energy distribution of normal modes vibrations was done using GAR2PED program. The HOMO and LUMO analysis are used to determine the charge transfer within the molecule. The stability of the molecule arising from hyperconjugative interaction and charge delocalization has been analyzed using NBO analysis. The calculated geometrical parameters are in agreement with the XRD data. The calculated first hyperpolarizability is high and the title compound is an attractive candidate for further studies in nonlinear optical applications. To estimate the chemical reactivity of the molecule, the molecular electrostatic potential is calculated for the optimized geometry of the molecule.

Rosline Sebastian, S. H.; Attia, Mohamed I.; Almutairi, Maha S.; El-Emam, Ali A.; Panicker, C. Yohannan; Van Alsenoy, Christian

2014-11-01

101

A validated 1 H NMR method for the determination of the  

E-print Network

in this paper. # 2003 Published by Elsevier B.V. Keywords: Chitosan; Chitin; pH-sensitive; IR, 1 H NMR, degree and is used in many industries such as food processing, cos- metics, waste management, water clarification chromatography (GPC) [17]. Unfortunately, these techniques often show considerable discrepancies in the obtained

Buschmann, Michael

102

In situ attenuated total reflectance Fourier transform infrared (ATR FT-IR) spectroscopy monitoring of 1,2-butylene oxide polymerization reaction by using iterative concentration-guided classical least squares.  

PubMed

There has been rapid growth in the application of in situ optical spectroscopy techniques for reaction and process monitoring recently in both academia and industry. Vibrational spectroscopies such as mid-infrared, near-infrared spectroscopy, and Raman spectroscopy have proven to be versatile and informative. Accurate determination of concentrations, based on highly overlapped spectra, remains a challenge. As an example, 1,2-butylene oxide (BO) polymerization, an important industrial reaction, initiated by propylene glycol (PG) and catalyzed by KOH, is studied in this work in a semi-batch fashion by using in situ attenuated total reflectance Fourier transform infrared spectroscopy (ATR FT-IR) monitoring. The weak BO absorbance, the constantly changing interference from the product oligomers throughout the course of the reaction, and the change in BO spectral features with system polarity posed challenges for quantitative spectral analysis based on conventional methods. An iterative concentration-guided classical least-squares (ICG-CLS) method was developed to overcome these challenges. Taking advantage of the concentration-domain information, ICG-CLS enabled the estimation of the pure oligomer product spectra at different stages of the semi-batch process, which in turn was used to construct valid CLS models. The ICG-CLS algorithm provides an in situ calibration method that can be broadly applied to reactions of known order. Caveats in its applications are also discussed. PMID:23876733

Chen, Xiaoyun; Pell, Randy; Sarsani, Sagar; Cramm, Brian; Villa, Carlos; Dixit, Ravindra

2013-08-01

103

Solvent effects on the relative stability of 4-nitro-1 H-imidazole and 5-nitro-1 H-imidazole. Ab initio and density functional theory calculations  

Microsoft Academic Search

Ab initio and density functional theory (DFT) calculations were carried out to investigate the relative stability of 4-nitro-1H-imidazole (1) and 5-nitro-1H-imidazole (2) in the gas phase and in solutions with different polarities. Solvent effects were examined by means of both the self-consistent isodensity polarized continuum method (SCI-PCM) and the self-consistent reaction field (SCRF) method. In the gas phase, both QCISD(T)\\/6-311++G??

Soo Gyeong Cho; Jin Rai Cho; Bang Sam Park

2000-01-01

104

IR Windstreaks  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

Windstreaks are features caused by the interaction of wind and topographic landforms. The raised rims and bowls of impact craters causes a complex interaction such that the wind vortex in the lee of the crater can both scour away the surface dust and deposit it back in the center of the lee. If you look closely, you will see evidence of this in a darker 'rim' enclosing a brighter interior.

This infrared image shows windstreaks in the region between Gordii Dorsum and Amazonis Mensa.

Image information: IR instrument. Latitude -15.8, Longitude 215 East (145 West). 97 meter/pixel resolution.

Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

2005-01-01

105

The Probability of Collision for Slow H+, (H1H1)+, (H1H2)+, (H2H2)+, (H2)+ and He+ Ions in Argon  

Microsoft Academic Search

The probability of collision Pc for slow H+, (H1H1)+, (H1H2)+, (H2H2)+, (H2)+ and He+ ions in argon has been measured. The energy range studied was 225 to 4200 volts for the H+ and (H1H1)+ ions, 225 to 1300 volts for the (H1H2)+, (H2H2)+ and He+ ions and 300 to 1225 volts for the deuteron hydrogen molecular ion (H1H1)+ beam. The

Edward B. Jordan

1935-01-01

106

Synthesis, experimental and theoretical investigations of some new 4,4?-bis(3-substituted-4,5-dihydro-1H-1,2,4-triazol-5-one-4-yl)diphenylmethane derivatives  

NASA Astrophysics Data System (ADS)

The 4,4'-bis(3-substituted-4,5-dihydro-1 H-1,2,4-triazol-5-one-4-yl)diphenylmethane derivatives 3 were synthesized in the cyclization reaction of semicarbazide derivatives 2 in alkaline solution. The synthesized compounds were characterized by elemental analyses, IR, 1H and 13C NMR, as well as MS. Molecular structure of compound 3a was determined by the X-ray analysis. Theoretical calculations (DFT/B3LYP/6-311G ??) of molecular structures were carried out for all final (cyclic) compounds. In addition vibrational spectrum of 3a was reproduced by means of the single-parameter and SQM scaling approaches and the assignment of bands was proposed. Investigated new compounds exhibit antinociceptive properties.

Pitucha, Monika; Borowski, Piotr; Karczmarzyk, Zbigniew; Fruzi?ski, Andrzej

2009-02-01

107

Characterization of heroin samples by 1H NMR and 2D DOSY 1H NMR.  

PubMed

Twenty-four samples of heroin from different illicit drug seizures were analyzed using proton Nuclear Magnetic Resonance ((1)H NMR) and two-dimensional diffusion-ordered spectroscopy (2D DOSY) (1)H NMR. A careful assignment and quantification of (1)H signals enabled a comprehensive characterization of the substances present in the samples investigated: heroin, its main related impurities (6-acetylmorphine, acetylcodeine, morphine, noscapine and papaverine) and cutting agents (caffeine and acetaminophen in nearly all samples as well as lactose, lidocaine, mannitol, piracetam in one sample only), and hence to establish their spectral signatures. The good agreement between the amounts of heroin, noscapine, caffeine and acetaminophen determined by (1)H NMR and gas chromatography, the reference method in forensic laboratories, demonstrates the validity of the (1)H NMR technique. In this paper, 2D DOSY (1)H NMR offers a new approach for a whole characterization of the various components of these complex mixtures. PMID:24378299

Balayssac, Stéphane; Retailleau, Emmanuel; Bertrand, Geneviève; Escot, Marie-Pierre; Martino, Robert; Malet-Martino, Myriam; Gilard, Véronique

2014-01-01

108

Synthesis of 3-(1Methyl1H-imidazol-2-ylthio)propanoic Acid and (E)-3-(1Methyl1H-imidazol-2-ylthio)acrylic Acid  

Microsoft Academic Search

The syntheses of 3-(1-methyl-1H-imidazol-2-ylthio)acrylic acid and 3-(1-methyl-1H-imidazol-2-ylthio)propanoic acid, mitochondria-targeted prodrugs of the antioxidant methimazole, are described. The method of Fan et al. (Fan et al., Synthesis2006, 2286) for the reaction of phenols with propiolic acid and propiolate esters was modified to synthesize (E)-3-(1-methyl-1H-imidazol-2-ylthio)acrylic acid. The intermediate tert-butyl (E)-3-(1-methyl-1H-imidazol-2-ylthio)acrylate was prepared by the reaction of tert-butyl propiolate with methimazole; the use

Christopher M. Hattan; Jalil Shojaie; Serrine S. Lau; M. W. Anders

2012-01-01

109

Step and pulse transient studies of IR-observable adsorbates during NO and CO reaction on Rh/SiO{sub 2}  

SciTech Connect

The dynamics and reactivity of infrared-observable adsorbates for the reaction of NO with CO over a 44% Rh/SiO{sub 2} catalyst have been studied by in situ infrared spectroscopy combined with steady-state isotopic and pulse NO-CO transient techniques. Steady-state isotopic transient results reveal that (i) a rapid exchange between the gaseous CO and adsorbed CO occurs on the Rh surface; (ii) Rh+({sup 12}CO)({sup 13}CO) is an intermediate for the exchange between Rh{sup +}({sup 12}CO){sub 2} and gaseous {sup 13} CO; (iii) the adsorbed NCO species is not directly involved in the formation of CO{sub 2}; (iv) the residence time of the intermediate for CO{sub 2} formation decreases with an increase in temperature from 473 to 573 K. At 573 K, rapid NO dissociation led to the high availability of surface oxygen, which results in CO{sub 2} response leading the CO response during steady-state isotopic transient studies. Pulse NO-CO transients further confirm that the NCO species is not a reaction intermediate in the formation of CO{sub 2}- Pulse NO-CO studies show that Rh-NO{sup -}, Rh-NCO, and CO{sub 2} are formed prior to gem-dicarbonyl; CO{sub 2} can be produced without involving the gem-dicarbonyl as an intermediate. Steady-state isotopic transient and pulse studies were excellent complementary techniques that provided an insight into the reactivity and dynamics of adsorbates under reaction condition. 40 refs., 7 figs., 2 tabs.

Krishnamurthy, R. [Tesa Tape Inc., Charlotte, NC (United States)] [Tesa Tape Inc., Charlotte, NC (United States); Chuang, S.S.C. [Univ. of Akron, OH (United States)] [Univ. of Akron, OH (United States); Balakos, M.W. [United Catalysts Inc., Louisville, KY (United States)] [United Catalysts Inc., Louisville, KY (United States)

1995-12-01

110

Eco-friendly one-pot synthesis of acetals and ketals by heterogeneously catalyzed liquid-solid phase reaction  

Microsoft Academic Search

Twelve classes of acetals and ketals were synthesized from aldehyde\\/ketone and glycol using TiSiW12O4\\/TiO2 as a novel eco-friendly catalyst. The physical characterizations were carried out by TG\\/DTA, FT-IR, XRD, and 1H NMR spectra. The results indicated that the catalyst showed excellent catalytic activity for the condensation reactions. The yield of 12 classes of acetals and ketals reached 56.3%-96.3% under the

Shuijin YANG; Min WANG; Yongguang LIANG; Jutang SUN

2006-01-01

111

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

NASA Astrophysics Data System (ADS)

We investigated the reactivity of O(1D) towards two types of hydrogen atoms in CH3OH. The reaction was initiated on irradiation of a flowing mixture of O3 and CD3OH or CH3OD 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(1D) + CD3OH, 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(1D) + CH3OD, 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(1D) inserts into the C-H and O-H bonds of CH3OH to form HOCH2OH and CH3OOH, 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 HOCH2OH or decomposition of CH3OOH. The former decomposition channel of HOCH2OH produces vibrationally more excited OH because of incomplete intramolecular vibrational relaxation, and decomposition of CH3COOH 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(1D) + CD3OH and CH3OD, 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.

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

2012-10-01

112

Catalytic Activity of Platinum Monolayer on Iridium and Rhenium Alloy Nanoparticles for the Oxygen Reduction Reaction  

SciTech Connect

A new type of electrocatalyst with a core?shell structure that consists of a platinum monolayer shell placed on an iridium? rhenium nanoparticle core or platinum and palladium bilayer shell deposited on that core has been prepared and tested for electrocatalytic activity for the oxygen reduction reaction. Carbon-supported iridium? rhenium alloy nanoparticles with several different molar ratios of Ir to Re were prepared by reducing metal chlorides dispersed on Vulcan carbon with hydrogen gas at 400 °C for 1 h. These catalysts showed specific electrocatalytic activity for oxygen reduction reaction comparable to that of platinum. The activities of PtML/PdML/Ir2Re1, PtML/Pd2layers/Ir2Re1, and PtML/Pd2layers/Ir7Re3 catalysts were, in fact, better than that of conventional platinum electrocatalysts, and their mass activities exceeded the 2015 DOE target. Our density functional theory calculations revealed that the molar ratio of Ir to Re affects the binding strength of adsorbed OH and, thereby, the O2 reduction activity of the catalysts. The maximum specific activity was found for an intermediate OH binding energy with the corresponding catalyst on the top of the volcano plot. The monolayer concept facilitates the use of much less platinum than in other approaches. The results with the PtML/PdML/Ir2Re electrocatalyst indicate that it is a promising alternative to conventional Pt electrocatalysts in low-temperature fuel cells.

Karan, Hiroko I.; Sasaki, Kotaro; Kuttiyiel, Kurian; Farberow, Carrie A.; Mavrikakis, Manos; Adzic, Radoslav R.

2012-05-04

113

Facile method for the combinatorial synthesis of 2,2-disubstituted quinazolin-4(1H)-one derivatives catalyzed by iodine in ionic liquids.  

PubMed

A mild and facile method for the combinatorial synthesis of quinazolin-4-(1H)-one derivatives, containing simple 2,2-disubstituted quinazolin-4-(1H)-ones, spirocyclic quinazolin-4-(1H)-ones, spiro-heterocyclic quinazolin-4-(1H)-ones, and dispirocyclic quinazolin-4-(1H)-ones, is described, which results in high yields by using ionic liquids as green media. The method involves the reaction of 2-aminobenzamides with various ketones catalyzed by iodine and provides new quinazolin-4-(1H)-one library for biomedical screening. PMID:20334422

Wang, Xiang-Shan; Yang, Ke; Zhou, Jie; Tu, Shu-Jiang

2010-07-12

114

The synthesis, structure and properties of N-acetylated derivatives of ethyl 3-amino-1H-pyrazole-4-carboxylate.  

PubMed

Ethyl 3-amino-1H-pyrazole-4-carboxylate (1) was yielded through total synthesis and reacted with acetic anhydride to give the acetylated products 2-6. Compounds 1-6 were studied with HPLC, X-ray, FT-IR, (1)H-NMR, (13)C-NMR and MS. Acetylation was carried out in solvents of various polarity, namely; chloroform; dioxane; DMF; acetic anhydride, at room temperature and at boiling points; and in the presence and absence of DMAP. The acetylated products are mainly nitrogen atoms in the ring. The position of the ring proton in the solution was based on NOESY; multinuclear HMBC, HSQC spectra and calculations. For equivalent amounts (1-1.5 mol) of acetic anhydride at room temperature two products of monoacetylation are produced in the ring: 2 and 3, ca. 2 : 1 and at the same time only small amount of the third product of monoacetylated, 5 in DMF, as well the product diacetylated, 4. The greatest amount of the product 4 is produced during the reaction with chloroform. However, in this solvent and in dioxane no product 5 is produced. Compound 2 is, largely, formed in dimethylformamide, in the presence DMAP, 0.2 eq. In the presence of this catalytic base, for the first hour, there is a mixture 2 and 3 to the ratio ca. 95 : 5. With 8 eq of Ac(2)O at reflux, after another hour, the compounds 3, 4 and 6 appear about equal amounts. After a longer time, the compound, which appears most in this mixture is triacetylated derivative 6. The structural and spectroscopic characteristics of compounds 1-6 have been given and the methods for their preparation have been provided. PMID:17473461

Kusakiewicz-Dawid, Anna; Masiukiewicz, Elzbieta; Rzeszotarska, Barbara; Dyba?a, Izabela; Kozio?, Anna Eugenia; Broda, Ma?gorzata Anna

2007-05-01

115

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

NASA Astrophysics Data System (ADS)

The title molecular salt, 2-mesityl-1H-benzo[d]imidazol-3-ium chloride (C16H17N2+·Cl?), was synthesized unexpectedly from the reaction of N-[(1E)-mesitylmethylene]benzene-1,2-diamine and CoCl2·6H2O, and characterized by elemental analysis, 1H 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 (C16H17N2+·Cl?) and nonionic forms (C16H16N2·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.

Özdemir, Nam?k

2012-06-01

116

Stereoselective ?-fluorination of N-acyloxazolidinones at room temperature within 1 h.  

PubMed

A direct ?-fluorination of N-acyloxazolidinones based on the unique reactivity of group IVa metal enolates has been developed. The reaction is an experimentally simple, low-cost, quick, and energy-efficient alternative for asymmetric ?-fluorination of N-acyloxazolidinones. Preliminary studies have shown compatibility with alkyl, alkenyl, and alkynyl, aromatic, and several heteroaromatic substituents. High diastereoselectivities have been achieved with most substrates tested, and the reaction is typically complete within 1 h at ambient temperature. PMID:24926887

Alvarado, Joseph; Herrmann, Aaron T; Zakarian, Armen

2014-07-01

117

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. PMID:20631832

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

2010-01-01

118

WebSpectra: 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 13C NMR, DEPT, COSY and IR spectra of various compounds for students to interpret.

119

Green chemistry approaches to the synthesis of 5-alkoxycarbonyl-4-aryl-3,4- dihydropyrimidin-2(1H)-ones by a three-component coupling of one-pot condensation reaction: comparison of ethanol, water, and solvent-free conditions.  

PubMed

A general and practical green chemistry route to the Biginelli cyclocondensation reaction using cerium(III) chloride as the catalyst (25% mol) is described under three different sets of reaction conditions. This method provides an efficient and much improved modification of original Biginelli reaction reported in 1893, in terms of high yields, short reaction times, and simple work-up procedure, and it has the ability to tolerate a wide variety of substitutions in all three components, which is lacking in existing procedures. PMID:12530887

Bose, D Subhas; Fatima, Liyakat; Mereyala, Hari Babu

2003-01-24

120

Selective synthesis of 2-aryl-1-arylmethyl-1 H-1,3-benzimidazoles in water at ambient temperature  

Microsoft Academic Search

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 silica sulfuric acid is reported. The reactions were performed in ethanol or water and the catalyst could be reused for several runs.

Peyman Salehi; Minoo Dabiri; Mohammad Ali Zolfigol; Somayeh Otokesh; Mostafa Baghbanzadeh

2006-01-01

121

1H NMR spectroscopic studies of selenosubtilisin.  

PubMed

Anomalously low-field signals in 1H NMR spectra of serine proteases provide valuable information on the protonation state of the catalytic histidine residue. We have examined the pH dependence of the deshielded protons of three different oxidation states of selenosubtilisin, a semisynthetic selenoenzyme with significant peroxidase activity, in order to evaluate the influence of the selenium prosthetic group on the hydrogen-bonding network in the modified active site. In the spectra of the anionic seleninate and selenolate derivatives, two resonances were observed at 18.0 and 15.5/14.0 ppm, assigned respectively to the N delta 1 and N epsilon 2 protons of protonated His64. These signals were apparent from pH 4 to above pH 10, indicating that the negatively charged prosthetic group increases the stability of the imidazolium dramatically, raising its pKa by at least 3-4 pH units. In contrast, a neutral selenenyl sulfide species exhibits no deshielded proton signals at 18 ppm at any pH but has a weak signal at 14.1 ppm above pH 7 which was assigned to the N delta 1 imidazole proton of neutral His64. While the pKa of His64 appears normal (approximately 7) in this derivative, the selenenyl sulfide substitution may alter the orientation of the imidazole ring within the active site for steric reasons. Together with data on the influence of pH on peroxidase activity, these results suggest that selenosubtilisin's His64 acts as a general acid facilitating the reduction of the selenenyl sulfide to selenolate by thiols. PMID:8461308

House, K L; Garber, A R; Dunlap, R B; Odom, J D; Hilvert, D

1993-04-01

122

Electrostatic influence of QA reduction on the IR vibrational mode of the 10a-ester C==O of HA demonstrated by mutations at residues Glu L104 and Trp L100 in reaction centers from Rhodobacter sphaeroides.  

PubMed

The light-induced QA-/QA FTIR difference spectrum of the photoreduction of the primary quinone (QA) in reaction centers (RCs) from Rhodobacter sphaeroides exhibits a set of complex differential bands between 1750 and 1715 cm(-1). Several of these features correspond in frequency to bands that bleach in the HA-/HA FTIR difference spectra of the photoreduction of the bacteriopheophytin electron acceptor (HA). Since the 10a-ester C==O from HA and the side chains of protonated carboxylic acids would be expected to contribute in this spectral region, mutations were designed at Trp L100 and Glu L104, which have been proposed to form hydrogen bonds to the 10a-ester and the 9-keto carbonyls on ring V of HA, respectively. The QA/-/QA spectra measured in IH2O and 2H2O of RCs from wild type (WT) were compared to those of RCs with the mutation Trp to Phe at L100 [WF(L100)], Glu to Leu at L104 [EL(L104)], or both mutations [EL(L104)/WF(L100)]. The spectra of the mutants in the 1800-1400 cm(-1) frequency range exhibit only limited perturbations compared to those of WT, indicating the absence of significant structural changes due to the mutations. Part of a differential signal centered around 1732 cm(-1) in the spectrum of WT RCs is downshifted by approximately 7 cm(-1) in EL(L104), while it is upshifted by approximately 11 cm(-1) in WF(L100). This upshift of the differential signal is assigned to the frequency change of the 10a-ester C==O of HA induced by the rupture of the hydrogen bond with Trp L100. The 1H2O-minus-2H2O double-difference spectrum of WT RCs exhibits a characteristic differential signal positive at 1730 cm-1 and negative at 1724 cm-1 that is absent in the corresponding spectra of EL(L104) and of the double mutant, implicating Glu L104 in the QA-/QA spectral changes. This differential signal is strongly modified in frequency and amplitude in the 1H2O-minus-2H2O spectrum of WF(L100), indicating that it does not correspond to a direct response of the C==O mode of the Glu L104 side chain upon QA reduction. Instead, perturbation of the hydrogen bond of the 9-keto C==O with Glu L104 is proposed to induce a change of electron density on ring V of HA, thereby altering the frequency of the 10a-ester C==O that is in partial conjugation with ring V. The loss of the hydrogen bond to the 9-keto C==O of HA due to the Glu L104 to Leu mutation or the alteration of the strength of the hydrogen bond by 1H/2H exchange on Glu L104 appears to produce such effects. Thus, the QA-/QA spectra above 1700 cm-1 are dominated by contributions from the 10a-ester C==O of HA, with most of the differential signals assigned to a small frequency downshift of the 10a-ester C==O of HA in response to QA reduction. The complexity of the signals implies a structural heterogeneity of the conformation and hydrogen bonding of the 10a-ester C==O of HA, which may be related to the functional heterogeneity observed in electron transfer kinetics. The present FTIR results show that the reduction of QA can induce a pronounced electrostatic effect on molecular vibrations of chemical groups located about 10 A away from QA. They also demonstrate that, within experimental limits, the proton uptake observed at pH 7 upon QA photoreduction [McPherson, P. H., Okamura, M. Y., & Feher, G. (1988) Biochim. Biophys. Acta 934, 348-368] involves none of the exchangeable carboxylic groups of the RC. PMID:9109660

Breton, J; Nabedryk, E; Allen, J P; Williams, J C

1997-04-15

123

Targeted hepatic overexpression of human IRS-1: postnatal effects in the developing mouse  

Microsoft Academic Search

Insulin receptor substrate-1 (IRS-1) is an intracellular docking protein involved in insulin and insulin-like growth factor (IGF) signaling. The present studies examine postnatal liver development in transgenic mice with targeted hepatic overexpression of human insulin receptor substrate-1 (hIRS-1). In mature animals, hIRS-1 overexpression augments liver growth. Based on our previous studies that have shown markedly attenuated insulin signaling in the

Peter J. Giannone; Barham K. Abu Dayyeh; Theresa C. Bienieki; Jack R. Wands; Philip A. Gruppuso

2004-01-01

124

Efficient synthesis of 3-(4,5-dihydro-1 H-imidazole-2-yl)-1 H-indoles  

Microsoft Academic Search

A simple method for the synthesis of various 3-(4,5-dihydro-1H-imidazole-2-yl)-1H-indoles is described. Treatment of different substituted indoles with 1-acetyl-imidazolidin-2-one in the presence of phosphorus oxychloride afforded after hydrolysis in ethanol the corresponding 3-(4,5-dihydro-1H-imidazole-2-yl)-1H-indoles in moderate to good yields.

Ulrike Hary; Ulrike Roettig; Michael Paal

2001-01-01

125

Regioselective synthesis of dispiro[1 H-indene-2,3?-pyrrolidine-2?,3?-[3 H]indole]-1,2?(1? H)-diones of potential anti-tumor properties  

Microsoft Academic Search

1,3-Dipolar cycloaddition reaction of 2-(arylmethylene)-2,3-dihydro-1H-inden-1-ones 1a–g with non-stabilized azomethine ylides, generated in situ via decarboxylative condensation of isatins 2a,b and sarcosine (3) afforded dispiro[1H-indene-2,3?-pyrrolidine-2?,3?-[3H]indole]-1,2?(1?H)-diones 4a–n and not the isomeric forms dispiro[1H-indene-2,4?-pyrrolidine-2?,3?-[3H]indole]-1,2?(1?H)-diones 5 in a highly regioselective manner. Anti-tumor activity screening for the synthesized compounds (4c,d,i–l) at a dose of 10?M utilizing 56 different human tumor cell lines representing, leukemia, melanoma

Adel S. Girgis

2009-01-01

126

Measurement of the partial cross sections {sigma}{sub TT}, {sigma}{sub LT}, and ({sigma}{sub T} + {epsilon}{sigma}{sub L}) of the {sup 1}H(e, e{sup '{pi}+})n reaction in the {Delta}(1232) resonance  

SciTech Connect

We report precision {sup 1}H(e, e{sup '{pi}+})n measurements in the {Delta}(1232) resonance at Q{sup 2}=0.127(GeV/c){sup 2} obtained at the MIT-Bates out-of-plane scattering facility. These are the lowest, but nonzero, Q{sup 2} measurements in the {pi}{sup +} channel. The data offer tests of the theoretical calculations, particularly of the background amplitude contributions. The chiral effective field theory and Sato-Lee model calculations are not in agreement with this experiment.

Kirkpatrick, J. M.; Calarco, J.; Holtrop, A. [Department of Physics, University of New Hampshire, Durham, New Hampshire 03824 (United States); Sparveris, N. F. [Department of Physics, Temple University, Philadelphia, Pennsylvania 19122 (United States); Nakagawa, I.; Bernstein, A. M.; Bertozzi, W.; Botto, T.; Casagrande, F.; Dow, K.; Farkondeh, M.; Gilad, S.; Kowalski, S.; Milner, R.; Sirca, S.; Stave, S.; Tsentalivich, G.; Tschalaer, C.; Turchinetz, W.; Zhou, Z.-L. [Department of Physics, Laboratory for Nuclear Science, and Bates Linear Accelerator Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

2011-08-15

127

Synthesis and characterization of 2,2";-(pyridine-2,6-diyl)bis(1H-benzo[d]imidazol-3-ium) 2,4,6-trimethylbenzenesulfonate chloride by experimental and theoretical methods  

NASA Astrophysics Data System (ADS)

The title molecular salt (2), 2,2";-(pyridine-2,6-diyl)bis(1H-benzo[d]imidazol-3-ium) 2,4,6-trimethylbenzenesulfonate chloride (C19H15N52+·C9H11O3S-·Cl-), was synthesized unexpectedly from the reaction of 2,6-bis(benzimidazol-2-yl)pyridine (1) with 2-mesitylenesulfonyl chloride. Spectroscopic techniques (FT-IR, NMR and UV-vis.) were used to characterize compounds 1 and 2. Solid-state structure of compound 2 was identified by X-ray crystallography. Theoretical characterization of the spectroscopic properties of compounds 1 and 2 was achieved using the density functional theory (DFT) method with the 6-311G(d,p) basis set, and the results were checked against the experimental data. Electronic absorption spectra of the compounds have also been obtained.

Özdemir, Nam?k; Dayan, Osman; Yava?o?lu, Melek Tercan; Çetinkaya, Bekir

2014-10-01

128

Synthesis of a rare 3D copper cyanide compound based on 3-(5-(pyridin-4-yl)-1H-1,2,4-triazol-3-yl)pyridine via the transformation of acetonitrile to inorganic cyanide  

NASA Astrophysics Data System (ADS)

One-pot solvothermal treatments of acetonitrile, water, LiOH, Cu(CH3COO)2·H2O and 3-(5-(pyridin-4-yl)-1H-1,2,4-triazol-3-yl)pyridine (HL) yielded a rare copper cyanide coordination polymer, [Cu2(L) (CN)]n (1). The existence of a cyanide group in compound 1 may be due to the decomposition of acetonitrile at the relatively high temperature (160 °C) and autogenous pressure of the reaction. Compound 1 has been characterized by single-crystal X-ray diffraction, XRPD, IR, and elemental analysis. Compound 1 is a 3D copper cyanide coordination polymer, and a ({6.8.10}2{6.8^3.10^2}) topology in 1 is created. In addition, the optical and catalytic properties have been investigated.

Yang, Linyan; Xin, Liangliang; Tian, Jinlei; Du, Peiyao; Wei, Xiaohua; Liao, Shengyun; Zhang, Yanping; Lv, Rui; Gu, Wen; Liu, Xin

2014-05-01

129

Further derivatives of 4-benzoyl-1,5-diphenyl-1 H -pyrazole-3-carboxylic acid and their antibacterial activities  

Microsoft Academic Search

Compound 4, 5, 6, 7, and 8 were synthesized from 4-benzoyl-1,5-diphenyl-1H-pyrazole-3-carboxylic acid 1 as a starting material. The pyrazolo[4,3-d]oxazinone 4 was obtained from direct reaction of the acid 1 with hydroxylamine hydrochloride. Acid chloride 2 was converted easily into the new derivatives consisting of 1-(4-benzoyl-1,5-diphenyl-1H-pyrazol-3-oyl)-sulfamide 5 and 3,4-dibenzoyl-1,5-diphenyl-1H-pyrazole 6. The nitrile derivative 7 was obtained by dehydration of the amide

?shak Bildirici; Ahmet ?ener; ?srafil Tozlu

2007-01-01

130

CHARLOTTE HARBOR IR, 2002  

EPA Science Inventory

The 2002 Charlotte Harbor Implementation Review (IR) summarizes the progress and challenges ahead for the Charlotte Harbor National Estuary Program (CHNEP). The implementation review report requires seven components: Status of CCMP implementation (programmatic progress); Environm...

131

Synthesis of novel pyrazolic analogues of chalcones and their 3-aryl-4-(3-aryl-4,5-dihydro-1 H-pyrazol-5-yl)-1-phenyl-1 H-pyrazole derivatives as potential antitumor agents  

Microsoft Academic Search

Novel (E)-1-aryl-3-(3-aryl-1-phenyl-1H-pyrazol-4-yl)prop-2-en-1-ones 5\\/6 (pyrazolic chalcones) were synthesized from a Claisen–Schmidt reaction of 3-aryl-1-phenylpyrazol-4-carboxaldehydes 4 with several acetophenone derivatives 1. Subsequently, the microwave-assisted cyclocondensation reaction of chalcones 5\\/6 with hydrazine afforded the new racemic 3-aryl-4-(3-aryl-4,5-dihydro-1H-pyrazol-5-yl)-1-phenyl-1H-pyrazoles 7 or their N-acetyl derivatives 8 and 9 when reactions where carried out in DMF or acetic acid, respectively. Several of these compounds were screened by

Braulio Insuasty; Alexis Tigreros; Fabián Orozco; Jairo Quiroga; Rodrigo Abonía; Manuel Nogueras; Adolfo Sanchez; Justo Cobo

2010-01-01

132

Synthesis, spectroscopic characterization, calculational studies and in vitro antitumoral activity of 4-(3-(1H-imidazol-1-yl)propyl)-(thiophen-2-ylmethyl)-1H-1,2,4-triazol-5(4H)-one  

NASA Astrophysics Data System (ADS)

4-(3-(1H-imidazol-1-yl)propyl)-(thiophen-2-ylmethyl)-1H-1,2,4-triazol-5(4H)-one (IPTT), C 13H 15N 5OS, was synthesized and characterized by 13C NMR, 1H NMR, IR and single-crystal X-ray diffraction. The structure of IPTT is stabilized by three intermolecular hydrogen bonds and by intermolecular C sbnd H⋯ ? interaction. The compound IPTT was modelled by using DFT method. Calculations of vibrational frequencies, gauge including atomic orbital (GIAO), 1H and 13C NMR chemical shifts of IPTT in the ground state, total electronic charge density map and frontier molecular orbitals were performed at B3LYP/6-31 G(d) level of theory were carried out by using DFT method with 6-31 G(d) basis set. The structural parameters obtained by geometry optimization, the theoretical vibrational frequencies and chemical shift values are in good agreement with experimental ones. FT-IR, NMR and X-ray analytical results of IPTT show that the compound exists as keto form, that was supported by DFT calculations. In addition, in vitro studies showed hopeful antitumoral activity of the title IPTT compound.

Süleymano?lu, Nevin; Ustaba?, Re?at; Alpaslan, Yelda Bingöl; Ünver, Yasemin; Turan, Mustafa; Sancak, Kemal

2011-03-01

133

17O, 1H coupling constants in intramolecular hydrogen bonds  

NASA Astrophysics Data System (ADS)

17O, 1H spin-spin coupling constants in systems with intramolecular hydrogen bonds are reported. The 17O NMR spectra, proton decoupling and the special DECOMPOSITION program were used. In asymmetrical systems, 17O, 1H coupling constants of about 80 Hz were found for one of the oxygen nuclei while for symmetrical systems 17O, 1H coupling constants of about 30 Hz were observed for both equivalent oxygen nuclei. The data on 17O, 1H coupling constants can be used to estimate the state of the proton in the hydrogen bond.

Bolkunov, I. A.; Sergeyev, N. M.; Shapet'ko, N. N.

1990-11-01

134

Nanopore structure buildup during endodontic cement hydration studied by time-domain nuclear magnetic resonance of lower and higher mobility 1H.  

PubMed

Time-domain nuclear magnetic resonance (TD-NMR) of (1)H nuclei has been used to monitor and model changes of endodontic cement pastes during hydration, from the initial reaction period up to hours and days. The (1)H in the samples are divided into two major spin groups by fitting each free induction decay, acquired after the second pulse of an inversion recovery (I-R) pulse sequence with variable interpulse delay, by the sum of a quasi-Gaussian (signal from low mobility nuclei) and an exponential (from higher mobility nuclei). The extrapolations to zero time of the signals from the two spin groups give two sets of I-R data that have been analyzed to give quasi-continuous T(1) distributions. After about a day, two clearly solid components appear. From a day to a few days, three liquid populations are identified, one of them mainly in the low-mobility spin group, which later merge, giving a single T(1) or T(2) peak. The rapid onset of the solid components, at the cost of the liquid, and the rapid changes of the relaxation time distributions of all components are clear indicators of the amount and kinetics of reaction products formation (C-S-H gel and Portlandite) and of the C-S-H micronanoporous structure buildup and evolution. At 30 days of hydration, the very short T(1) and T(2) liquid component (T(1) congruent with 200 micros and T(2) congruent with 50 micros) can be assigned to C-S-H intralayer water (thickness of the order of fractions of a nanometer) and the remaining liquid signal to interlayer water (thickness of the order of 1 nm). Comparisons are made among a widely used commercial endodontic cement paste and two more recent commercial pastes, with additive compounds to make the hydration process faster and to increase the workability. Parameters can be extracted from the data to characterize the different kinetics and nanostructure of the pore space formed up to 30 days. The parameters are in agreement with the expected effects of the additives, so the parameters can be used to optimize the formulation of new pastes, in order to improve their therapeutic performance. PMID:20085239

Gombia, Mirko; Bortolotti, Villiam; De Carlo, Boris; Mongiorgi, Romano; Zanna, Silvano; Fantazzini, Paola

2010-02-11

135

Efficient synthesis and solid state analysis of 3-(1 H-pyrrol-2-yl)quinoxalin-2(1 H)-one and 2-(1 H-pyrrol-2-yl)-1 H-benzo[ d]imidazole from pyrrolo-2-ylglyoxyl acid  

Microsoft Academic Search

The synthesis of new pyrrole-functionalized quinoxalines and benzimidazole is described. Our methodology involves the condensation between 2-oxo-2-(1H-pyrrol-2-yl)acetic acid and differently substituted 1,2-phenylene diamines. Depending on the substitution and on the reaction conditions, the synthesis leads to either the pyrrolyl-quinoxaline or -benzimidazole heterocycles. Further insights concerning the structural arrangement of the pyrrolyl-quinoxaline were obtained by solid state analysis, revealing an inverted

Florence Szydlo; Bruno Andrioletti; Eric Rose; Carine Duhayon

2008-01-01

136

Dual emission from an ortho-metalated Ir(III) complex  

SciTech Connect

Several complexes of Ir(III) containing both the bidentate N-coordinating ligand 2,2'-bipyridine (bpy) and the N,C-orthometalating ligand 2-phenylpyridine (ppy) have recently been prepared; these include the two species Ir(ppy)/sub 2/(bpy)/sup +/ (A) and Ir(ppy)(bpy)/sub 2//sup 2 +/ (B). The former was prepared from the dichloro-bridged dimer, (Ir(ppy)/sub 2/Cl)/sub 2/, by modification of the procedure of Nonoyama while the latter was obtained by reaction of cis-(Ir(bpy)/sub 2/(OSO/sub 2/CF/sub 3/)/sub 2/) (CF/sub 3/SO/sub 3/) with ppy in refluxing 2-ethoxyethanol. The purity of the complexes was monitored with thin-layer chromatography using silica gel plates and 1:1:1 acetone/methanol/water mixtures for elution. Samples of the complexes used in these studies showed only one component in thin-layer chromatography. While only one isomer of B is possible, there are three possible isomers of A. Data from /sup 1/H and /sup 13/C NMR experiments indicate that A has C/sub 2/ symmetry. The NMR spectrum indicates, as does thin-layer chromatography, that only a single isomer of A is present with no detectable impurities due to a mixture of isomers. While X-ray structural data for A are lacking, structural data for related complexes suggest that A is the isomer with cisoid metal-carbon bonds and bpy metal-nitrogen bonds transoid to the metal-carbon bonds and bpy metal-nitrogen bonds transoid to the metal-carbon bonds. These species were prepared in order to probe further the effects of metal-carbon bonding on energy-transfer processes and electron-transfer reactions of metal complexes. Emission spectroscopic studies reported here reveal unusual and distinct intramolecular energy-transfer behavior in these complexes. Whereas dual emission from the former is observed in glasses at 77 K, a single emission is observed in the latter.

King, K.A.; Watts, R.J.

1987-03-04

137

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. PMID:21947918

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

2011-01-01

138

Modulation of the alternative complement pathways by beta 1 H globulin  

PubMed Central

C3b inactivator accelerator (A-C3bINA) was isolated from human plasma. An antiserum produced against the purified protein gave a reaction of identity with beta 1 H, a well-documented contaminant of C3 preparations. Beta 1 H appears to be composed of a single polypeptide chain containing a significant quantity of carbohydrate, and having a sedimentation coefficient of 5.6 on analytical, and 6.4 on sucrose density gradient ultracentrifugation. Its mol wt based on SDS polyacrylamide gel electrophoresis and equilibrium sedimentation is approximately 150,000, whereas it elutes from Sephadex G200 with an apparent mol wt of 300,000, suggesting that beta 1 H is an asymmetric molecule. Beta 1 H potentiates the inactivation of C3b by C3b inactivator, binds to EAC43 to limit the formation of EAC43bB and EAC43bBP, and in contrast to C3b inactivator, it increases the rate of loss of hemolytic sites from EAC43bB and EAC43bBP. For the C3b inactivator-potentiating effect, beta 1 H and C3b inactivator must necessarily be simultaneously present. The kinetics of inactivation of C3b by C3b inactivator and beta 1 H are first order, suggesting that potentiation is not a multistep process. The mechanisms of binding to C3b and inhibition of the alternative pathway convertases C3bB and C3bBP are currently unknown. PMID:62817

1976-01-01

139

Suzuki Cross-Coupling Reactions: Synthesis of Unsymmetrical Biaryls in the Organic Laboratory  

NASA Astrophysics Data System (ADS)

An organic chemistry laboratory experiment in which unsymmetrical biaryl alcohols are synthesized in a two-step process is described. In the first step, an aryl boronic acid is coupled with p-bromoacetaldehyde or p-bromoacetophenone. The carbonyl group of the product is reduced with sodium borohydride in the second step. The products of both reactions are solids that can be easily purified by recrystallization. The primary purpose in implementing this experiment was to give students additional exposure to transition-metal-catalyzed reactions. The experiment provides an opportunity to discuss a number of topics, including the palladium-catalyzed cross-coupling mechanism, reactions that permit the formation of C-C bonds in an aqueous environment, the reduction of carbonyl groups with metal hydrides, and atropisomerism. The students can use IR and 1H NMR spectroscopy to determine the structure of their products, and so this laboratory also allows them to improve their spectral interpretation skills.

Callam, Christopher S.; Lowary, Todd L.

2001-07-01

140

Multicolor IR emissive pixels  

NASA Astrophysics Data System (ADS)

We have evaluated several methods for generating multi-color emission for IR scene projector applications. The baseline requirements we employed were the ability to simulate color temperatures in the range 300-3000 K, minimum radiance levels consistent with existing IR sensor requirements, 1000 Hz frame rates and manufacturability. The analysis led us to down select two independent approaches that are capable of meeting HWIL multicolor requirements. We describe and discuss each of the approaches, their expected performance as well as their limitations.

Lannon, J.; Grego, S.; Solomon, S.

2007-04-01

141

Superconductor IR detector research  

NASA Astrophysics Data System (ADS)

A development status report is presented for efforts in the testing and characterization of high temperature superconducting thin films (HTSTFs) in the role of IR detectors. While none of the HTSTFs thus far tested was specifically formulated to serve in an IR sensing capacity, the results obtained have confirmed the ability of the test apparatus devised to obtain accurate, reliable, and repeatable detector performance data. The initial HTSTF tests were conducted on BaCuO films sputtered on strontium titanate substrates. Chips made from the films were 5 x 5 mm and approximately 2 microns thick.

Meuser, L. H.; Thiede, D. A.; McDonald, P.; Garcia, J.

1989-10-01

142

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

143

Coded IR proximity detector  

Microsoft Academic Search

The coded IR proximity detector is able to generate an electrical signal when the distance between the detector and a certain object becomes shorter than a preset value. The detector may be used as an automotive indicator and control. The detector consists of four parts: a controller, a transmitter, a receiver and the optical system, used both for transmission and

Tudor Zisu; Sorin Miclos

2001-01-01

144

HWIL IR imaging testing  

Microsoft Academic Search

The Army simulator facilities are presently configured to conduct hardware-in-the-loop mission tasks on the HELLFIRE and COPPERHEAD missile systems. These systems presently use a LASER seeker. The facility is an ideal candidate to be converted to include infrared (IR) seekers used on the TGSM system. This study investigates the possibility and impact of a facility update. This report documents the

R. J. Vinson; R. D. Passwater

1981-01-01

145

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

146

Novel 1H low field nuclear magnetic resonance applications for the field of biodiesel  

PubMed Central

Background Biodiesel production has increased dramatically over the last decade, raising the need for new rapid and non-destructive analytical tools and technologies. 1H Low Field Nuclear Magnetic Resonance (LF-NMR) applications, which offer great potential to the field of biodiesel, have been developed by the Phyto Lipid Biotechnology Lab research team in the last few years. Results Supervised and un-supervised chemometric tools are suggested for screening new alternative biodiesel feedstocks according to oil content and viscosity. The tools allowed assignment into viscosity groups of biodiesel-petrodiesel samples whose viscosity is unknown, and uncovered biodiesel samples that have residues of unreacted acylglycerol and/or methanol, and poorly separated and cleaned glycerol and water. In the case of composite materials, relaxation time distribution, and cross-correlation methods were successfully applied to differentiate components. Continuous distributed methods were also applied to calculate the yield of the transesterification reaction, and thus monitor the progress of the common and in-situ transesterification reactions, offering a tool for optimization of reaction parameters. Conclusions Comprehensive applied tools are detailed for the characterization of new alternative biodiesel resources in their whole conformation, monitoring of the biodiesel transesterification reaction, and quality evaluation of the final product, using a non-invasive and non-destructive technology that is new to the biodiesel research area. A new integrated computational-experimental approach for analysis of 1H LF-NMR relaxometry data is also presented, suggesting improved solution stability and peak resolution. PMID:23590829

2013-01-01

147

Kinetics of rearrangement of 2,4-dichlorophenyl-(1H-1,2,4-triazol-1-ylmethyl)ketone enol acetate  

Microsoft Academic Search

The kinetics of rearrangement of 2,4-dichlorophenyl(1H-1,2,4-triazol-1-ylmethyl)ketone enol acetate into 2,4-dichlorophenyl(5-acetyl-1H-1,2,4-triazol-l-ylmethyl)ketone were investigated by1H NMR spectroscopy. It was shown that this rearrangement is a first-order reaction. The rate constant was measured in the 129–156°C range and the activation parameters of the reaction were determined. A hypothesis concerning the intramolecular character of the observed rearrangement was drawn based on the kinetic data.

M. Z. Krimer; O. M. Radul; L. N. Margolin; I. V. Feofanova; L Ya Bogel'fer; V. V. Negrebetskii

1992-01-01

148

Versatile reactivity of half-sandwich Ir and Rh complexes toward carboranylamidinates and their derivatives: synthesis, structure, and catalytic activity for norbornene polymerization.  

PubMed

Synthesis, structure, and reactivity of carboranylamidinate-based half-sandwich iridium and rhodium complexes are reported for the first time. Treatment of dimeric metal complexes [{Cp*M(?-Cl)Cl}(2)] (M = Ir, Rh; Cp* = ?(5)-C(5)Me(5)) with a solution of one equivalent of nBuLi and a carboranylamidine produces 18-electron complexes [Cp*IrCl(Cab(N)-DIC)] (1?a; Cab(N)-DIC = [iPrN=C(closo-1,2-C(2)B(10)H(10))(NHiPr)]), [Cp*RhCl(Cab(N)-DIC)] (1?b), and [Cp*RhCl(Cab(N)-DCC)] (1?c; Cab(N)-DCC = [CyN=C(closo-1,2-C(2)B(10)H(10))(NHCy)]). A series of 16-electron half-sandwich Ir and Rh complexes [Cp*Ir(Cab(N')-DIC)] (2?a; Cab(N')-DIC = [iPrN=C(closo-1,2-C(2)B(10)H(10))(NiPr)]), [Cp*Ir(Cab(N')-DCC)] (2?b, Cab(N')-DCC = [CyN=C(closo-1,2-C(2)B(10)H(10)(NCy)]), and [Cp*Rh(Cab(N')-DIC)] (2?c) is also obtained when an excess of nBuLi is used. The unexpected products [Cp*M(Cab(N,S)-DIC)], [Cp*M(Cab(N,S)-DCC)] (M = Ir 3?a, 3?b; Rh 3?c, 3?d), formed through BH activation, are obtained by reaction of [{Cp*MCl(2)}(2)] with carboranylamidinate sulfides [RN=C(closo-1,2-C(2)B(10)H(10))(NHR)]S(-) (R = iPr, Cy), which can be prepared by inserting sulfur into the C-Li bond of lithium carboranylamidinates. Iridium complex 1?a shows catalytic activities of up to 2.69×10(6) ?g(PNB) mol(Ir)(-1) h(-1) for the polymerization of norbornene in the presence of methylaluminoxane (MAO) as cocatalyst. Catalytic activities and the molecular weight of polynorbornene (PNB) were investigated under various reaction conditions. All complexes were fully characterized by elemental analysis and IR and NMR spectroscopy; the structures of 1?a-c, 2?a, b; and 3?a, b, d were further confirmed by single crystal X-ray diffraction. PMID:22009699

Yao, Zi-Jian; Su, Ge; Jin, Guo-Xin

2011-11-18

149

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

150

?-Oxido-bis-[hydridotris(tri-methyl-phosphane-?P)iridium(III)](Ir--Ir) bis-(tetra-fluorido-borate) dihydrate  

PubMed Central

The title compound, [Ir2H2O(C3H9P)6](BF4)2·2H2O, was isolated from the reaction between [Ir(COD)(PMe3)3]BF4 and H2 in water (COD is cyclo­octa-1,5-diene). The asymmetric unit consists of one IrIII atom bonded to three PMe3 groups, one hydride ligand and half an oxide ligand, in addition to a BF4 ? counter-ion and one water molecule of hydration. The single oxide ligand bridging two IrIII atoms is disordered across an inversion center with each O atom having a 50% site occupancy. Each IrIII atom has three PMe3 groups occupying facial positions, with the half-occupancy O atoms, a hydride ligand and an Ir—Ir bond completing the coordination sphere. The Ir—Ir distance is 2.8614?(12)?Å, comparable to other iridium(III) metal–metal bonds. Two water mol­ecules hydrogen bond to two BF4 ? anions in the unit cell. PMID:24826089

Merola, Joseph; Husebo, Trang Le

2014-01-01

151

One-pot synthesis of 3,4-dihydropyrimidin-2(1 H)-ones using boric acid as catalyst  

Microsoft Academic Search

A simple effective synthesis of 3,4-dihydropyrimidin-2(1H)-one derivatives, using boric acid as catalyst, from aromatic aldehydes, 1,3-dicarbonyl compounds and urea in glacial acetic acid is described. Compared with the classical Biginelli reaction conditions, this new method has the advantage of excellent yields (86–97%) and short reaction time (0.5–2 h).

Shujang Tu; Fang Fang; Chunbao Miao; Hong Jiang; Youjian Feng; Daqing Shi; Xiangshan Wang

2003-01-01

152

Template-free synthesis of AlPO 4-H1, -H2, and -H3 by microwave heating  

Microsoft Academic Search

Aluminophosphate molecular sieves (AlPO4's) were prepared by microwave heating without using organic template reagents. The microwave heating enhanced the crystallization of aluminophosphate gels, and AlPO4-H1, -H2(AHT), and -H3(APC) were successfully obtained as single phases in a relatively short reaction time. The reaction conditions used for the crystallization of the three kinds of AlPO4's were very similar to each other, but

Katsuyuki Kunii; Kazuhiro Narahara; Shoji Yamanaka

2002-01-01

153

Solvent influence in the formation of normal and abnormal carbene complexes in reactions of imidazolium salts with [Ir(H)2(PPh3)2(OCMe2)2]BF4  

E-print Network

: Abnormal Normal Carbene Iridium compounds Tetrahydrofuran Dichloromethane a b s t r a c t Abnormal)2(OCMe2)2]BF4 at room temperature in tetrahydrofuran (THF) or dichloromethane (CH2Cl2). Reactions in THF

Baltisberger, Jay H.

154

A matrix isolation FT–IR and quasirelativistic density functional theory investigation of the reaction products of laser-ablated uranium atoms with NO, NO2 and N2O  

Microsoft Academic Search

The reaction products of laser-ablated uranium atoms with nitrogen oxide reagent gases were trapped in excess argon at 6–7 K. Infrared spectra of the resulting matrices revealed the presence of several new product species. Major bands at 983.6 and 818.9 cm?1 in the infrared spectra of the reaction products of U atoms with 14N16O are due to the U–N and

Gary P. Kushto; Philip F. Souter; Lester Andrews; Matthew Neurock

1997-01-01

155

Enhanced anhydrous proton conduction in binary mixtures of 1H-imidazole1H-1,2,3-triazole based compounds  

E-print Network

Enhanced anhydrous proton conduction in binary mixtures of 1H-imidazole�1H-1,2,3-triazole based-(4-(dodecyloxy) phenyl)-1H-imidazole (4) and 5-(4-(dodecyloxy)phenyl)-1H-1,2,3-triazole (10). We have found such as 1H-imid- azole or 1H-1,2,3-triazole have been considered due to their ability to form hydrogen bond

Auerbach, Scott M.

156

Abrogation of the alloreactive responses of cadaveric donor intestinal lymphocytes by intraoperative Campath-1H exposure.  

PubMed

A number of recent reports in clinical and experimental intestinal transplantation have suggested that the donor lymphocytes present in and around the gastrointestinal system are potent mediators of graft-versus-host (GvH) reactivity and that GvH responses may contribute to posttransplant morbidity. Therefore, we have tested the proliferative and cytotoxic capabilities of gut-associated lymphocytes from cadaveric donors obtained prerevascularization (pre-r) and about 6 hours postrevascularization (post-r) in recipients pretreated with Campath-1H antibody (alemtuzumab). Mixed lymphocyte reactions (MLR) were performed with lymphoid cells isolated from intestinal epithelial mucosa, lamina propria, and lymph nodes. The pre-r lymphocytes responded strongly to both the recipient and third-party alloantigenic stimulating cells. However, similar preparations from the post-r samples responded in MLR at significantly lower levels (P < .01). This post-r decrease in responsiveness was not observed in similar lymphocyte samples obtained from donors of recipients not treated with Campath-1H. Both the pre-r and post-r samples had similar flow cytometric profiles, suggesting that there was no receptor loss in these lymphoid tissues by the short-term 6-hour exposure to Campath-1H given to the recipient. Conversely, in preliminary experiments where the donor were treated with Campath-1H, it was observed that very few lymphocytes could be obtained from intestinal tissues (n = 3). These results suggested that Campath-1H treatment of the recipient could bring about a drastic reduction in an otherwise strong GvH reactivity by the donor intestinal immune cells. PMID:15848725

Mathew, J M; Defaria, W; Kato, T; Blomberg, B; Carreno, M; Santiago, S; Weppler, D; Esquenazi, V; Miller, J; Tzakis, A G

2005-03-01

157

A matrix isolation FT-IR and quasirelativistic density functional theory investigation of the reaction products of laser-ablated uranium atoms with NO, NO2 and N2O  

NASA Astrophysics Data System (ADS)

The reaction products of laser-ablated uranium atoms with nitrogen oxide reagent gases were trapped in excess argon at 6-7 K. Infrared spectra of the resulting matrices revealed the presence of several new product species. Major bands at 983.6 and 818.9 cm-1 in the infrared spectra of the reaction products of U atoms with 14N16O are due to the U-N and U-O stretching vibrations, respectively, of the linear NUO molecule. Weaker absorptions at 845.9 cm-1 and 718.3 cm-1 in similar experiments are indicative of a "T" shaped NUO2 species. A weaker 1017.0 cm-1 band provides evidence for the cation/anion pair [NUO]+[NO]-. Several possible products of the reaction of uranium atoms with nitrogen oxides have been further characterized by quasirelativistic density functional calculations.

Kushto, Gary P.; Souter, Philip F.; Andrews, Lester; Neurock, Matthew

1997-04-01

158

Biotransformation and toxicokinetics of the insect repellent IR3535® in male and female human subjects after dermal exposure.  

PubMed

The absorption and excretion of the insect repellent IR3535(®) was studied in human subjects (five males and five females) after dermal application of approx. 3g of a formulation containing 20% IR3535(®), i.e. the amounts of IR3535(®) applied were between 1.94 and 3.4 mmol/person (418-731 mg/person). Blood and urinary concentrations of IR3535(®) and its only metabolite, IR3535(®)-free acid, were determined over time. In plasma, concentrations of the parent compound IR3535(®) were at or below the limit of quantification (0.037 ?mol/L). IR3535(®)-free acid peaked in plasma samples 2-6h after dermal application. Cmax mean values were 5.7 ?mol/L in males, 3.0 ?mol/L in females and 4.2 ?mol/L in all volunteers. Mean AUC values were 41.6, 24.5 and 33.9 ?molL(-1)h in males, females and all subjects, respectively. In urine samples from all human subjects, both IR3535(®) and IR3535(®)-free acid were detectable, however, only very small amounts of IR3535(®) were found. Concentrations of IR3535(®)-free acid were several thousand-fold higher than the parent compound and peaked at the first two sampling points (4h and 8h after dermal application). Overall, IR3535(®) and IR3535(®)-free acid excreted with urine over 48 h representing 13.3 ± 3.05% of the dose applied. Since IR3535(®) is rapidly and extensively metabolized, and IR3535(®)-free acid has a low molecular weight and high water solubility, it is expected that urinary excretion of IR3535(®)-free acid and IR3535(®) represents the total extent of absorption of IR3535(®) in humans. Based on the results of this study, the skin penetration rate of IR3535(®) is 13.3% in humans after dermal application. PMID:23402938

Broschard, Thomas H; Bohlmann, Anja M; Konietzny, Stefan; Schauer, Ute M D; Dekant, Wolfgang

2013-04-26

159

Cd(II) and Zn(II) complexes of two new hexadentate Schiff base ligands derived from different aldehydes and ethanol amine; X-ray crystal structure, IR and NMR spectroscopy studies  

NASA Astrophysics Data System (ADS)

Four new [Cd(H2L1)(NO3)]ClO4 (1), [Zn(H2L1)](ClO4)2 (2), [Cd(H2L2)(NO3)]ClO4 (3), and [Zn(H2L2)](ClO4)2 (4), complexes were prepared by the reaction of two new Schiff base ligands and Cd(II) and Zn(II) metal ions in equimolar ratios. The ligands H2L1 and H2L2 were synthesized by reaction of 2-[2-(2-formyl phenoxy)ethoxy]benzaldehyde and/or 2-[2-(3-formyl phenoxy)propoxy]benzaldehyde and ethanol amine and characterized by IR, 1H and 13C NMR spectroscopy. All complexes were characterized by IR, 1H and 13C NMR, COSY, and elemental analysis. Also, the complex 1 was characterized by X-ray in addition to the above methods. The X-ray crystal structure of compound 1 showed that all nitrogen and oxygen atoms of ligand (N2O4) and a molecule of nitrate with two donor oxygen atom have been coordinated to the metal ion and the Cd(II) ion is in an eight-coordinate environment that is best described as a distorted dodecahedron geometry.

Golbedaghi, Reza; Rezaeivala, Majid; Albeheshti, Leila

2014-11-01

160

Experimental and DFT studies on the vibrational spectra of 1H-indene-2-boronic acid  

NASA Astrophysics Data System (ADS)

Stable conformers and geometrical molecular structures of 1H-indene-2-boronic acid (I-2B(OH)2) were studied experimentally and theoretically using FT-IR and FT-Raman spectroscopic methods. FT-IR and FT-Raman spectra were recorded in the region of 4000-400 cm-1, and 3700-400 cm-1, respectively. The optimized geometric structures were searched by Becke-3-Lee-Yang-Parr (B3LYP) hybrid density functional theory method with 6-31++G(d,p) basis set. Vibrational wavenumbers of I-2B(OH)2 were calculated using B3LYP density functional methods including 6-31++G(d,p) basis set. Experimental and theoretical results show that density functional B3LYP method gives satisfactory results for predicting vibrational wavenumbers except OH stretching modes which is probably due to increasing unharmonicity in the high wave number region and possible intra and inter molecular interaction at OH edges. To support the assigned vibrational wavenumbers, the potential energy distribution (PED) values were also calculated using VEDA 4 (Vibrational Energy Distribution Analysis) program.

Alver, Özgur; Kaya, Mehmet Fatih

2014-11-01

161

Synthesis, structural, theoretical studies and biological activities of 3-(arylamino)-2-phenyl-1H-inden-1-one derivative  

NASA Astrophysics Data System (ADS)

Five derivatives of 2-phenyl-1H-indene-1-one have been prepared and fully characterized. Spectroscopic techniques such as FT-IR, 1H NMR, mass spectrometry, and elemental analysis were used to investigate the chemical structures and physical properties of the prepared compounds. The optimized structures and the distribution of the frontier molecular orbital were obtained using density functional theory (DFT) at B3LYP/6-311++G(d,p) level of theory. Additionally, the UV spectral properties of the indene compounds were corroborated by frontier orbital (HOMO and LUMO) calculations. Intramolecular charge transfer (ICT) peak has been observed in the UV spectra of the compounds and theoretically confirmed by the HOMO and LUMO analysis. The potential use of these compounds as antibacterial agents was investigated. The results show that indene-1-one derivatives have an antibacterial activity for both gram-negative (Pseudomonas aeruginosa) and gram-positive (Methicillin Resistant Staphylococcus aureus) bacteria.

El-Sheshtawy, Hamdy S.; Abou Baker, Ahmed M.

2014-06-01

162

Determination of the delta(2H/1H)of Water: RSIL Lab Code 1574  

USGS Publications Warehouse

Reston Stable Isotope Laboratory (RSIL) lab code 1574 describes a method used to determine the relative hydrogen isotope-ratio delta(2H,1H), abbreviated hereafter as d2H of water. The d2H measurement of water also is a component of the National Water Quality Laboratory (NWQL) schedules 1142 and 1172. The water is collected unfiltered in a 60-mL glass bottle and capped with a Polyseal cap. In the laboratory, the water sample is equilibrated with gaseous hydrogen using a platinum catalyst (Horita, 1988; Horita and others, 1989; Coplen and others, 1991). The reaction for the exchange of one hydrogen atom is shown in equation 1.

Revesz, Kinga; Coplen, Tyler B.

2008-01-01

163

Asymmetric organocatalytic synthesis of 4,6-bis(1H-indole-3-yl)-piperidine-2 carboxylates.  

PubMed

We developed an asymmetric organocatalytic synthesis of 4,6-bis(1H-indole-3-yl)-piperidine-2-carboxylates using 10 mol% of a chiral phosphoric acid. The products, which are novel bisindole-piperidine-amino acid hybrids, can be obtained in one step from 3-vinyl indoles with imino esters in dichloromethane at room temperature after 1 h of reaction time. A variety of these compounds could be synthesized in up to 70% yield and 99% ee, and they were experimentally and computationally analyzed regarding their relative and absolute stereochemistry. PMID:24733144

Zhong, Sabilla; Nieger, Martin; Bihlmeier, Angela; Shi, Min; Bräse, Stefan

2014-05-28

164

A general Pd/Cu-catalyzed C-H heteroarylation of 3-bromoquinolin-2(1H)-ones.  

PubMed

3-(Heteroaryl)quinolin-2(1H)-ones were synthesized in good to excellent yields using a bimetallic catalytic system through the C-H heteroarylation strategy. Starting from 3-bromoquinolin-2(1H)-ones, various azoles have been successfully used. In all cases, the reactions take place rapidly in dioxane and efficiently proceed in the presence of a bimetallic Pd(OAc)2/CuI as the catalyst, PPh3 as the ligand and LiOtBu or KOAc as the base. PMID:25237986

Bruneau, Alexandre; Brion, Jean-Daniel; Messaoudi, Samir; Alami, Mouad

2014-10-01

165

Eco-friendly and facile synthesis of 2-substituted-1 H-imidazo[4,5- b]pyridine in aqueous medium by air oxidation  

Microsoft Academic Search

We report a new environmentally-benign, convenient, and facile methodology for the synthesis of 2-substituted-1H-imidazo[4,5-b]pyridine. The reaction of 2,3-diaminopyridine with substituted aryl aldehydes in water under thermal conditions without the use of any oxidative reagent has been studied. The reaction has yielded 1H-imidazo[4,5-b]pyridine derivatives by an air oxidative cyclocondensation reaction in one step in an excellent yield. Furthermore, a series of

Rajesh P. Kale; Mohammad U. Shaikh; Ganesh R. Jadhav; Charansingh H. Gill

2009-01-01

166

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

167

Synthesis, structure and reactivity of [Ir(dippe)(l-Cl)]2, [Ir(dippe)2][Ir(dippe)Cl2] and [Ir(dippe)2]Cl  

E-print Network

Synthesis, structure and reactivity of [Ir(dippe)(l-Cl)]2, [Ir(dippe)2][Ir(dippe)Cl2] and [Ir 2004 Abstract [Ir(COD)(l-Cl)]2 reacts with two equivalents of 1,2-bis(diisopropylphosphino)ethane (dippe) to produce [Ir(dippe)(l-Cl)]2 (1a) in yields that are dependent upon the solvent. Its single

Jones, William D.

168

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

2012-06-01

169

Metabolite Characterization in Peritoneal Dialysis Effluent Using High-resolution 1H and 1H-13C NMR Spectroscopy  

E-print Network

Metabolite analysis of peritoneal dialysis (PD) effluent may provide information regarding onset and progression of complications associated with prolonged PD therapy. In this context, the NMR detectable small metabolites of PD effluent samples were characterized using high resolution 1H and 1H-13C NMR spectroscopy. The various spectra were recorded (at 800 MHz proton frequency) on PD effluent samples obtained after 4 hour (intraperitoneal) dwell time from patients with end stage renal failure (ESRF) and continuing normally on PD therapy. Inspite of devastating spectral feature of PD effluent due to the presence of intense resonances from glucose and lactate, we were able to identify about 53 small endogenous metabolites (including many complex coupled spin systems) and more than 90 % of the total CH cross peaks of 1H-13C HSQC spectrum were identified specific to various metabolites of PD effluent. We foresee that the characteristic fingerprints of various metabolites of control PD effluent samples will be us...

Guleria, Anupam; Rawat, Atul; Khetrapal, C L; Prasad, Narayan; Kumar, Dinesh

2014-01-01

170

Isomer Dependence in the Assembly and Lability of Silver(I) Trifluoromethanesulfonate Complexes of the Heteroditopic Ligands, 2-, 3-, and 4-[Di(1H-pyrazolyl)methyl]phenyl(di-p-tolyl)phosphine.  

PubMed

Three isomers of a new heteroditopic ligand that contains a di(1H-pyrazolyl)methyl (-CHpz2) moiety connected to a di(p-tolyl)phosphine group via a para-, meta-, or ortho-phenylene spacer (pL, mL, and oL, respectively) have been synthesized by using a palladium(0)-catalyzed coupling reaction between HP(p-tolyl)2 and the appropriate isomer of (IC6H4)CHpz2. The 1:1 complexes of silver(I) trifluoromethanesulfonate, Ag(OTf), were prepared to examine the nature of ligand coordination and the type of supramolecular isomer (monomeric, cyclic oligomeric, or polymeric) that would be obtained. The single crystal X-ray diffraction studies showed that [Ag(pL)](OTf), 1, and [Ag(mL)](OTf), 2, possessed cyclic dimeric dications, whereas [Ag(oL)](OTf), 3, was a coordination polymer. The polymeric chain in 3 could be disrupted by reaction with triphenylphosphine, and the resulting complex, [Ag(oL)(PPh3)](OTf), 4, possessed a monometallic cation where the ligand was bound to silver in a chelating ?(2)P,N- coordination mode. The solution structures of 1-4 were probed via a combination of IR, variable-temperature multinuclear ((1)H, (13)C, (31)P) NMR spectroscopy, as well as by electron spray ionization (ESI)(+) mass spectrometry. A related complex [Ag(m-IC6H4CHpz2)2](OTf), 5, was also prepared, and its solid-state and solution spectroscopic properties were studied for comparison purposes. These studies suggest that the cyclic structures of 1 and 2 are likely preserved but are dynamic in solution at room temperature. Moreover, both 3 and 4 have dynamic solution structures where 3 is likely extensively dissociated in CH3CN or acetone rather than being polymeric as in the solid state. PMID:25375040

Gardinier, James R; Hewage, Jeewantha S; Lindeman, Sergey V

2014-11-17

171

Facile synthesis of 1-alkoxy-1H-benzo- and 7-azabenzotriazoles from peptide coupling agents, mechanistic studies, and synthetic applications  

PubMed Central

Summary (1H-Benzo[d][1,2,3]triazol-1-yloxy)tris(dimethylamino)phosphonium hexafluorophosphate (BOP), 1H-benzo[d][1,2,3]triazol-1-yl 4-methylbenzenesulfonate (Bt-OTs), and 3H-[1,2,3]triazolo[4,5-b]pyridine-3-yl 4-methylbenzenesulfonate (At-OTs) are classically utilized in peptide synthesis for amide-bond formation. However, a previously undescribed reaction of these compounds with alcohols in the presence of a base, leads to 1-alkoxy-1H-benzo- (Bt-OR) and 7-azabenzotriazoles (At-OR). Although BOP undergoes reactions with alcohols to furnish 1-alkoxy-1H-benzotriazoles, Bt-OTs proved to be superior. Both, primary and secondary alcohols undergo reaction under generally mild reaction conditions. Correspondingly, 1-alkoxy-1H-7-azabenzotriazoles were synthesized from At-OTs. Mechanistically, there are three pathways by which these peptide-coupling agents can react with alcohols. From 31P{1H}, [18O]-labeling, and other chemical experiments, phosphonium and tosylate derivatives of alcohols seem to be intermediates. These then react with BtO? and AtO? produced in situ. In order to demonstrate broader utility, this novel reaction has been used to prepare a series of acyclic nucleoside-like compounds. Because BtO? is a nucleofuge, several Bt-OCH2Ar substrates have been evaluated in nucleophilic substitution reactions. Finally, the possible formation of Pd ?–allyl complexes by departure of BtO? has been queried. Thus, alpha-allylation of three cyclic ketones was evaluated with 1-(cinnamyloxy)-1H-benzo[d][1,2,3]triazole, via in situ formation of pyrrolidine enamines and Pd catalysis. PMID:25246951

Singh, Manish K; Kumar, Mukesh; Chamala, Raghu Ram; Yedulla, Vijayender R; Wagner, Domenick; Leung, Evan; Yang, Lijia; Matin, Asha; Ahmad, Sadia

2014-01-01

172

A study of petroleum alkylcarbazoles using 1H NMR spectroscopy  

Microsoft Academic Search

A precision method for measuring proton chemical shift calculations of methylcarbazoles has been developed. For other abundant substituents the proton chemical shift correlation diagrams are reported. The method makes it possible to identify a number of carbazole structures present in petroleums. General structural regularities of petroleum carbazoles have been defined from 1H NMR data. Methylcarbazole isomers with 1- and 1,8-substituents

M. B. Smirnov; E. B. Frolov

1997-01-01

173

Quantification of in vivo 1 H Magnetic Resonance  

E-print Network

Quantification of in vivo 1 H Magnetic Resonance Spectroscopy (MRS) signals with baseline into account the macromolecular baseline contribution: (a) based on macromolecules and lipids measured in vivo prior knowledge from a database of inversion recovery signals. The ultimate goal is to measure

174

Diagnostic Performance 1 H after Simulation Training Predicts Learning  

ERIC Educational Resources Information Center

Although simulation training improves post-training performance, it is unclear how well performance soon after simulation training predicts longer term outcomes (i.e., learning). Here our objective was to assess the predictive value of performance 1 h post-training of performance 6 weeks later. We trained 84 first year medical students a simulated…

Consoli, Anna; Fraser, Kristin; Ma, Irene; Sobczak, Matthew; Wright, Bruce; McLaughlin, Kevin

2013-01-01

175

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

176

A study of 192Ir production conditions at an electron accelerator  

NASA Astrophysics Data System (ADS)

This communication deals with the conditions of 192Ir isotope production under a nonreactor technology via the 193Ir(?, n)192Ir reaction. It can be carried out by irradiation of a target from natural iridium with the high-energy X-ray of an electron accelerator. The possibility of increasing the photonuclear yield of the target isotope by addition of the 191Ir( n, ?)192Ir reaction induced by moderated photoneutrons has been shown. For this, an X-ray converter and a target were placed inside a neutron moderator. Data on the 192Ir and admixture yields for the techniques using the moderator and without it have been obtained by computer simulation and experimentally.

Dovbnya, A. N.; Rogov, Yu. V.; Shevchenko, V. A.; Shramenko, B. I.; Tenishev, A. Eh.; Torgovkin, A. V.; Uvarov, V. L.

2014-09-01

177

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

2009-01-01

178

? decay of the ?h11/2 isomer in Ir164  

NASA Astrophysics Data System (ADS)

The ?-decay branch of the ?h11/2 isomer in Ir164 has been identified using the GREAT spectrometer. The Ir164 nuclei were produced using the 92Mo(78Kr,p5n )164Ir reaction and separated in flight using the recoil ion transport unit (RITU) gas-filled separator. The measured ?-decay energy of 6880±10 keV allowed the excitation of the ?h11/2 state in Re160 to be deduced as 166±14 keV. The half-life of Ir164 was measured with improved precision to be 70±10?s and an ?-decay branching ratio of 4±2% was determined. Improved half-life and branching ratio measurements were also obtained for Ir165, but no evidence was found for the ground-state decays of either Ir164 or Ir165.

Drummond, M. C.; O'Donnell, D.; Page, R. D.; Joss, D. T.; Capponi, L.; Cox, D. M.; Darby, I. G.; Donosa, L.; Filmer, F.; Grahn, T.; Greenlees, P. T.; Hauschild, K.; Herzan, A.; Jakobsson, U.; Jones, P. M.; Julin, R.; Juutinen, S.; Ketelhut, S.; Leino, M.; Lopez-Martens, A.; Mistry, A. K.; Nieminen, P.; Peura, P.; Rahkila, P.; Rinta-Antila, S.; Ruotsalainen, P.; Sandzelius, M.; Sarén, J.; Say??, B.; Scholey, C.; Simpson, J.; Sorri, J.; Thornthwaite, A.; Uusitalo, J.

2014-06-01

179

Radicals and Hydroxy Radical Reactions in Troposphere  

E-print Network

with same molecule? { Which dominates? Depends on reaction rates-details of conditions and molecule. The art that OH can abstract in an exothermic reaction, this generally occurs #15; Bond strengths important: O HRadicals and Hydroxy Radical Reactions in Troposphere Examples of ground state radicals: 1. H atom

Schofield, Jeremy

180

Figure 1. In vivo 1 H NMR spectra of the  

E-print Network

Figure 1. In vivo 1 H NMR spectra of the hippocampus (bottom row), thalamus (middle row in thalamus (white), striatum (gray) and hippocampus (black) quantified in LCModel. Error bars represent ), thalamus (6.5 x 3.5 x 2.5 mm3 ) and striatum (7.7 x 3.0 x 3.0 mm3 ) were selected based on MR images

181

Cosmological solutions for model with a $1/H^{2}$ term  

E-print Network

We drive the cosmological solutions of five-dimensional model with $1/H^{2}$ term $(H^{2}\\equiv H_{MNPQ}H^{MNPQ})$, where $H_{MNPQ}$ is 4-form field strength. The behaviors of the scale factors and the scalar potential in effective theory are examined.As a consequence, we show that the universe changes from decelerated expansion to accelerated expansion in Einstein frame of the four-dimensional theory.

Masato Ito

2006-11-07

182

1-(2,4,6-Trialkylphenyl)-1H-Phospholes with a Flattened P-Pyramid: Synthesis and Reactivity  

NASA Astrophysics Data System (ADS)

The 1H-phospholes with a 2,4,6-trialkylphenyl substituent on the phosphorus atom synthesized in our laboratories are of aromatic character due to their flattened P-pyramid. Hence, they may undergo aromatic electrophilic substitution, such as Friedel-Crafts acylations. The arylphospholes were functionalized via the regioselective reaction with phosphorus tribromide to give substituted phospholes that may be ligands in rhodium complexes used in hydro-formylations. Despite their aromaticity, the arylphospholes may be involved in Diels-Alder cycloaddition with dienophiles to provide 7-phosphanorbornene derivatives useful in fragmentation - related phosphorylations. At elevated temperature, the aryl-1H-phospholes were converted to the 2H-derivatives by a sigmatropic rearrangement to furnish, after trapping, 1-phosphanorbornadienes. The complexation and the oxidation reactions of the sterically hindered arylphospholes are also discussed.

Keglevich, György

183

Why current IR engines fail  

Microsoft Academic Search

Observations from a unique investigation of failure analysis of Information Retrieval (IR) research engines are presented. The Reliable Information Access (RIA) Workshop invited seven leading IR research groups to supply both their systems and their experts to an effort to analyze why their systems fail on some topics and whether the failures are due to system flaws, approach flaws, or

Chris Buckley

2004-01-01

184

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

185

On the local sensitivity of different IR techniques: Ba species relevant in NO(x) storage-reduction.  

PubMed

IR spectroscopy is widely used to elucidate reaction mechanisms in NO(x) storage and reduction (NSR). Observed band positions and assignments of vibrational modes, however, differ remarkably among the various investigations. We report an IR study of barium species relevant in NSR, aiming to clarify the source of the reported discrepancies and different surface and bulk sensitivity of various IR measurement configurations. Four IR techniques, namely, transmission IR spectroscopy (TIRS), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), attenuated total reflection infrared spectroscopy (ATR-IRS), polarization-modulation infrared reflection-absorption spectroscopy (PM-IRRAS), all suitable for in situ studies of the reaction system, were used. Depending on the IR technique certain bands undergo a clear band shift or disappearance, evidently showing different surface and bulk sensitivity. In spectra of barium nitrate recorded by the more bulk sensitive IR techniques, i.e. TIRS, ATR-IRS, and PM-IRRAS, fewer bands appeared than in the more surface sensitive DRIFTS spectra. This work constitutes a collection of IR spectra of reference barium compounds for the clarification of species present in the NSR catalyst system. The band position or the presence of certain bands assigned to the same chemical species may deviate if the spectra were measured by different IR techniques, especially if the compared IR techniques differ in surface/bulk sensitivity. This implies that the band assignment valid for spectra measured by DRIFTS can be transferred to TIRS, ATR-IRS, and PM-IRRAS only with precautions. PMID:18846310

Roedel, Eva; Urakawa, Atsushi; Kureti, Sven; Baiker, Alfons

2008-10-28

186

Electrochemical and spectroelectrochemical studies of (TPP)(Ir(CO)/sub 3/)/sub 2/) in nonaqueous media  

SciTech Connect

A modified method for the synthesis of (TPP)(Ir(CO)/sub 3/)/sub 2/ from (Ir(CO)/sub 3/Cl)/sub 2/ and (TPP)H/sub 2/ where TPP is the dianion of tetraphenylporphyrin was developed and gives a much higher percent yield. Electrochemical and spectroelectrochemical studies of (TPP)(Ir(CO)/sub 3/)/sub 2/ indicate that this binuclear Ir(I) complex undergoes two reversible reductions at the porphyrin /pi/-ring system. Three irreversible oxidations are observed in benzonitrile containing 0.2 M tetrabutylammonium perchlorate, while in CH/sub 2/Cl/sub 2/, only two irreversible oxidations are recorded. The first oxidation occurs at one of the two Ir(I) centers of (TPP)(Ir(CO)/sub 3/)/sub 2/ and is followed by a rapid chemical reaction that leads to the generation of ((TPP)Ir)/sup +/ClO/sub 4//sup /minus// or a solvated form of this species in solution. An overall mechanism for the electrochemical conversion of binuclear (TPP)(Ir(CO)/sub 3/)/sub 2/ to monomeric ((TPP)Ir)/sup +/ClO/sub 4//sup /minus// and the additional reactions of this species are reported. Comparisons are also made between electrochemical properties of binuclear (TPP)(Ir(CO)/sub 3/)/sub 2/ and the binuclear Rh(I) analogue (TPP)(Rh(CO)/sub 2/)/sub 2/.

Kadish, K.M.; Deng, Y.J.; Yao, C.L.; Anderson, J.E.

1988-09-01

187

Ionic Liquid Promoted Eco-friendly and Efficient Synthesis of 2,3-Dihydroquinazolin-4(1 H )-ones  

Microsoft Academic Search

Summary.  2,3-Dihydroquinazolin-4(1H)-ones were efficiently synthesised by the reaction of isatoic anhydride, a primary amine or ammonium acetate, and different\\u000a aromatic aldehydes in 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim]BF4) without using any acidic catalyst. Also a bis-derivative of the title compound as a polyheterocyclic system was synthesised\\u000a successfully in high yield.

Minoo Dabiri; Peyman Salehi; Mostafa Baghbanzadeh

2007-01-01

188

IR fiber sources for scene projection  

Microsoft Academic Search

Naval Research Laboratory has developed IR transmitting fiber and IR fiber sources which can be used for HWIL testing. IR transmitting fiber is capable of broad transmission from near IR to LWIR and can be formed into bundles for imaging. IR fiber sources are based on rare earth doped glass or nonlinear processes in the glass and are cable of

L. B. Shaw; J. S. Sanghera; I. D. Aggarwal

2007-01-01

189

Elevated 1?h postload plasma glucose levels identify adults with normal glucose tolerance but increased risk of non-alcoholic fatty liver disease  

PubMed Central

Objective To determine the ability of the proposed diagnostic value of a 1-h OGTT glucose ?155mg/dL to identify individuals with non-alcoholic fatty liver disease (NAFLD) diagnosed by ultrasonography in a cohort of adult white individuals. Design The study group comprised 710 white individuals participating to the CATAnzaro MEtabolic RIsk factors (CATAMERI) Study, a cross-sectional study assessing cardio-metabolic risk factors in individuals carrying at least one risk factor including dysglycemia, overweight/obesity, hypertension, dyslipidemia. a 75 g oral Oral Glucose Tolerance Test (OGTT) was performed with 0, 30, 60, 90 and 120 min sampling for plasma glucose and insulin measurements. Cardio-metabolic risk factors including alanine aminotransferase (ALT), aspartate aminotransferase (AST), and gamma-glutamyltransferase (GGT) were assessed in the whole cohort. Results Of the 710 participants examined, 295 had normal glucose tolerance (NGT) with 1-hour post-load plasma glucose <155 mg/dL (NGT 1h-low), 109 individuals had NGT 1h-high, 104 had isolated impaired fasting glucose (IFG), and 202 had impaired glucose tolerance (IGT). As compared with NGT 1h-low, NGT 1h-high and IGT subjects exhibited significantly higher body mass index (BMI), triglycerides, high sensitivity C reactive protein, ALT, GGT, and hepatic insulin resistance (IR), assessed by the liver IR index, as well as lower high density lipoprotein, and insulin-like growth factor-1 (IGF-1) levels. In a logistic regression analysis adjusted for age, gender, and BMI, NGT 1h-high participants had a 1.5-fold increased risk of having NAFLD and an even increased risk was observed in subjects with IGT (1.8-fold), but not in the isolated IFG group (1.01-fold). Conclusions These data suggest that the value of a 1-hour OGTT glucose ?155 mg/dL may be helpful to identify a subset of NGT individuals at risk for NAFLD.

Sesti, Giorgio; Hribal, Marta Letizia; Fiorentino, Teresa Vanessa; Sciacqua, Angela; Perticone, Francesco

2014-01-01

190

CHHC and [superscript 1]H–[superscript 1]H magnetization exchange: Analysis by experimental solid-state NMR and 11-spin density-matrix simulations  

E-print Network

A protocol is presented for correcting the effect of non-specific cross-polarization in CHHC solid-state MAS NMR experiments, thus allowing the recovery of the [superscript 1]H–[superscript 1]H magnetization exchange ...

Aluas, Mihaela

191

Infrared Assisted Production of 3,4-Dihydro-2(1H)-pyridones in Solvent-Free Conditions  

PubMed Central

A green approach for the synthesis of a set of ten 4-aryl substituted-5-alcoxy carbonyl-6-methyl-3,4-dihydro-2(1H)-pyridones using Meldrum’s acid has been devised, the absence of solvent and the activation with infrared irradiation in addition to a multicomponent protocol are the main reaction conditions. The transformations proceeded with moderated yields (50–75%) with a reasonable reaction rate (3 h). It is worth noting that two novel molecules of the new class of the bis-3,4-dihydropyridones were also obtained. In addition, a comparison without the use of infrared irradiation was performed. PMID:21731463

Noguez, M. Olivia; Marcelino, Vanessa; Rodriguez, Hortensia; Martin, Osnieski; Martinez, Joel O.; Arroyo, Gabriel A.; Perez, Francisco J.; Suarez, Margarita; Miranda, Rene

2011-01-01

192

Synthesis and biological evaluation of 3-hydroxymethyl-5-(1H-1,2,3-triazol) isoxazolidines.  

PubMed

A synthetic approach towards a series of 3-hydroxymethyl-5-(1H-1,2,3-triazol)isoxazolidines has been reported, according to a procedure based on the cycloaddition reaction, under microwave irradiation, of a nitrone with 1-vinyl triazoles, prepared by a click reaction of azides with alkynes. Biological tests show that the synthesized compounds are able to inhibit proliferation of follicular and anaplastic human thyroid cancer cell lines, with IC50 values ranging from 3.87 to 8.76 lM. The obtained compounds induce caspase-3 activation and DNA fragmentation prevalently in follicular human thyroid cancer cell lines. PMID:24436994

Romeo, Roberto; Giofrè, Salvatore V; Carnovale, Caterina; Campisi, Agata; Parenti, Rosalba; Bandini, Lorenzo; Chiacchio, Maria A

2013-12-15

193

Ralf Siebenmorgen IR instrument from Antarctica (thermal) IR instruments from Antarctica  

E-print Network

Ralf Siebenmorgen IR instrument from Antarctica (thermal) IR instruments from Antarctica: what can Antarctica Atmospheric optical thickness spectrum #12;Ralf Siebenmorgen IR instrument from Antarctica Siebenmorgen IR instrument from Antarctica Paranal Dome C (30m) Atmospheric transmission #12;Ralf Siebenmorgen

Siebenmorgen, Ralf

194

Synthesis and antimicrobial evaluation of some new fluorinated spiro[[1,5] -benzothiazepin-2,3?[3? H]-indol]-2?(1? H)-ones  

Microsoft Academic Search

A series of fluorinated spiro[1,5-benzothiazepin-2,3?[3?H]-indol]-2?(1?H)-ones have been prepared by the reaction of 2-aminobenzene-thiols with 1,3-dihydro-3-[2-phenyl\\/(4-fluorophenyl)-2-oxoethylidene)-indol-2(1H)-ones (I) under microwave irradiation in open vessels using ethylene glycol as energy transfer medium and thermally in absolute ethanol saturated with hydrogen chloride gas. The comparative studies indicated that the microwave assisted organic synthesis has advantages of significantly reduced reaction time, improved yields and cleaner

Anshu Dandia; Mani Upreti; Babita Rani; U. C. Pant; I. J. Gupta

1998-01-01

195

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

196

The use of phosphite-type ligands in the Ir-catalyzed asymmetric hydrogenation of heterocyclic compounds.  

PubMed

A series of chiral phosphite-type ligands was tested in asymmetric Ir-catalyzed hydrogenation of quinolines and 2,4,5,6-tetrahydro-1H-pyrazino(3,2,1-j,k)carbazole. Hydrogenation of quinaldine hydrochloride provided superior enantioselectivity up to 65% ee compared to quinaldine free base. The ligands were tested for the first time in the asymmetric Ir-Ircatalyzed hydrogenation of 2,4,5,6-tetrahydro-1H-pyrazino(3,2,1-j,k)carbazole yielding the antidepressant drug, pirlindole. PMID:24272955

Lyubimov, Sergey E; Ozolin, Dmitry V; Ivanov, Pavel Yu; Melman, Artem; Velezheva, Valeriya S; Davankov, Vadim A

2014-01-01

197

IR fiber sources for scene projection  

NASA Astrophysics Data System (ADS)

Naval Research Laboratory has developed IR transmitting fiber and IR fiber sources which can be used for HWIL testing. IR transmitting fiber is capable of broad transmission from near IR to LWIR and can be formed into bundles for imaging. IR fiber sources are based on rare earth doped glass or nonlinear processes in the glass and are cable of high brightness IR emission. Recently, NRL developed a four emitter MWIR fiber source which is capable of high temperature simulation, high dynamic range, and fast response. New broadband fiber sources based upon IR supercontinuum generation in IR fibers are also being developed. In this paper, we will report on these technologies.

Shaw, L. B.; Sanghera, J. S.; Aggarwal, I. D.

2007-04-01

198

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 creatine/phosphocreatine (Cr/PCr) were subject to change as a function of exercise. In particular, the dipolar-coupled methylene protons of Cr/PCr 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 2protons of Cr/PCr to 1H MR spectra of human muscle in vivoreflect 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

199

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

200

[Expression of phytase gene phyA in Yarrowia lipolytica po1h].  

PubMed

Using the polymmerse chain reaction (PCR), we amplified the phytase gene phyA from Pichia pastoris GS115-phyA in Aspergillus niger NRRL3135 without the signal peptide sequence and intron sequence,. Then, it was cloned into pINA1297 vector to generate a recombinant vector of pINA1297-phyA. pINA1297-phyA was linearized and transformed into Yarrowia lipolytica po1h by the lithium acetate method. The positive transformants were obtained by YNB(casa) and PPB plates, after induced in YM medium at 28 degrees C for 6 day. The activity of the expressed phytase phyA reached 636.23 U/mL. The molecular weight of the enzyme was 130 kDa measured with SDS-PAGE analysis, whereas its molecular size reduced to 51 kDa after deglycosylation which is correspond with theoretical value. The enzymatic analysis of the recombinant phytase phyA revealed its optimal pH and temperature was 5.5 and 55 degrees C, which had high activity after incubated in pH ranged from 2.0 to 8.0 for 1 h. Moreover, its activity remained 86.08% after exposure to 90 degrees C for 10 min. It also was resistant to pepsin or trypsin treatment. PMID:20684304

Chen, Yun; Zou, You; Wang, Yiding; Ma, Lixin

2010-05-01

201

Optical/IR from ground  

NASA Technical Reports Server (NTRS)

Optical/infrared (O/IR) astronomy in the 1990's is reviewed. The following subject areas are included: research environment; science opportunities; technical development of the 1980's and opportunities for the 1990's; and ground-based O/IR astronomy outside the U.S. Recommendations are presented for: (1) large scale programs (Priority 1: a coordinated program for large O/IR telescopes); (2) medium scale programs (Priority 1: a coordinated program for high angular resolution; Priority 2: a new generation of 4-m class telescopes); (3) small scale programs (Priority 1: near-IR and optical all-sky surveys; Priority 2: a National Astrometric Facility); and (4) infrastructure issues (develop, purchase, and distribute optical CCDs and infrared arrays; a program to support large optics technology; a new generation of large filled aperture telescopes; a program to archive and disseminate astronomical databases; and a program for training new instrumentalists)

Strom, Stephen; Sargent, Wallace L. W.; Wolff, Sidney; Ahearn, Michael F.; Angel, J. Roger; Beckwith, Steven V. W.; Carney, Bruce W.; Conti, Peter S.; Edwards, Suzan; Grasdalen, Gary

1991-01-01

202

Complete 1H and 13C NMR spectra of pregnenolone.  

PubMed

Assignments for signals from 1H and 13C in the NMR spectra of pregnenolone (1), 16-dehydropregnenolone (2), and the 3-acetate of 1 (3) were validated by two-dimensional correlated spectroscopy (2D COSY) and heteronuclear single quantum coherence (HSQC). The narrow band of overlapping signals from H-7, H-2, and H-4 was resolved by exploiting three-bond coupling in the 2D COSY spectra and heteronuclear correlation. Assignments were based on high intensity cross peaks from long-range coupling by H-18 with H-17 and H-12 (axial). Similar cross peaks were observed for H-17 with H-21. Low intensity cross peaks were seen for H-4 coupled with H-6 and H-7, and also H-16 (quasi-axial) with H-14 of 1 and 3. Assignments based on 2D COSY spectra were confirmed by correlation peaks from HSQC. This now corrects the earlier conflicts among assignments reported for 13C signals of 1 and 3. Accurate assignments were similarly derived for signals from C-2, C-7, C-8, and C-21 of 1 and 3, and C-15 and C-16 of 1, 2, and 3. The complete sets of 1H and 13C NMR data for pregnenolone, pregnenolone 3-acetate, and 16-dehydropregnenolone serve as reference standards. PMID:7676476

Szendi, Z; Forgó, P; Sweet, F

1995-06-01

203

Optimal IR: How Far Away?  

Microsoft Academic Search

\\u000a There exists a gap between what a human user wants in mind and what (s)he could get from the information retrieval (IR) systems\\u000a by his\\/her queries. We say an IR system is perfect if it could always provide the users with what they want in their minds if available in corpus, and optimal if it could present to the users

Xiangdong An; Xiangji Huang; Nick Cercone

2010-01-01

204

Results of IR working group  

SciTech Connect

The IP luminosity at the Eloisatron will direct very large fluxes of hadronic debris into the IR quads. For instance at 1.10{sup 35} cm{sup 2}/sec the flux corresponds to 180 kilowatts. Already at the SSC fluxes in the neighborhood of 2 kilowatts are expected to require special handling. Scaling from SSC design experience we propose a configuration for the first IR quads at the Eloisatron capable of handling the heat load and radiation problems.

Ritson, D. (Stanford Linear Accelerator Center, Menlo Park, CA (United States) Superconducting Super Collider Lab., Dallas, TX (United States))

1992-03-01

205

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] [National Research Council of Canada, Ottawa, Ontario (Canada). Steacie Inst. for Molecular Sciences

1999-07-01

206

Eco-efficient one-pot synthesis of quinazoline-2,4(1H,3H)-diones at room temperature in water.  

PubMed

An efficient one-pot synthesis of quinazoline-2,4(1H,3H)-diones was developed. First, the reactions of anthranilic acid derivatives with potassium cyanate afforded the corresponding urea derivatives. Then, cyclization of the urea derivatives with NaOH afforded the monosodium salts of benzoylene urea. Finally, HCl treatment afforded the desired products in near-quantitative yields. This is an eco-efficient method because all the reactions were carried out in water, and the desired products were obtained simply by filtration. The aqueous filtrate was the only waste generated from the reaction. We scaled up the reaction to 1 kg starting material, thus establishing an alternative approach for the green synthesis of quinazoline-2,4(1H,3H)-diones in the chemical and pharmaceutical industries. PMID:24920051

Tian, Xin-Chuan; Huang, Xing; Wang, Dan; Gao, Feng

2014-01-01

207

Synthesis and caspase-3 inhibitory activity of 8-sulfonyl-1,3-dioxo-2,3-dihydro-1H-pyrrolo[3,4-c]quinolines.  

PubMed

A convenient synthesis of novel 8-sulfonyl-1,3-dioxo-4-methyl-2,3-dihydro-1H-pyrrolo[3,4-c]quinolines is described. As key steps to assemble the target molecular scaffold, our method features (a) Pfitzinger reaction of isatin-5-sulfonate 1 with methyl 3-oxo-3-phenylpropanoate, (b) formation of 1-(1H-pyrazol-4-yl)-1H-pyrrole-2,5-dione intermediate 5, and (c) reaction of sulfinic acid 9 with acrylate or methylacrylate leading to the corresponding sulfonyl propionates. Two compounds, ester 11 and morpholide 13, have been identified as potent inhibitors of caspase-3 with IC50 = 6 nM. Our primary data suggest noncompetitive and reversible character of caspase-3 inhibition. PMID:16182295

Kravchenko, Dmitri V; Kysil, Volodymyr M; Tkachenko, Sergey E; Maliarchouk, Sergey; Okun, Ilya M; Ivachtchenko, Alexandre V

2005-10-01

208

Synthesis and Antimicrobial Activity of 2-[2-(2,6-dichloro phenyl)amino]benzyl-3-(5-substituted phenyl-4,5-dihydro-1H-pyrazol-3-yl-amino)-6,8-dibromoquinazolin-4(3H)ones  

PubMed Central

A series of 2-[2-(2,6-dichlorophenyl)amino]benzyl-3-(5-substituted phenyl-4,5-dihydro-1H-pyrazol-3-yl-amino)-6,8-dibromoquinazolin-4(3H) ones 6a-m have been synthesized by the reaction of 2-[2-(2,6-dichlorophenyl)amino]benzyl-3-substituted phenylacrylamido-6,8-dibromoquinazolin-4(3H) ones 5a-m with hydrazine hydrate in the presence of glacial acetic acid. The chalcones 5a-m were prepared by the condensation of 2-[2-(2,6-dichlorophenyl)amino]benzyl-3-acetamido-6,8-dibromoquinazolin-4(3H)one 4 with different substituted aromatic aldehyde. The benzoxazinone 2 was synthesized from 2-[2-(2,6-dichlorophenyl)amino]phenyl acetyl chloride 1 on treatment with 3,5-dibromoanthranilic acid in pyridine, which on reaction with hydrazine hydrate and then on acetylation reaction yielded 4. The structures of these compounds have been elucidated by elemental analyses, IR, and NMR spectral data. The title compounds pyrazolyl-quinazolin-4(3H)ones 6a-m were evaluated for their antibacterial and antifungal activities in vitro. PMID:21264122

Patel, NB; Patel, JC; Barat, GG

2010-01-01

209

Bimetallic iridium(III) complexes consisting of Ir(ppy)(2) units (ppy = 2-phenylpyridine) and two laterally connected N/\\N chelates as bridge: synthesis, separation, and photophysical properties.  

PubMed

Reaction of the precursor complex Ir2(ppy)4Cl2 (ppy = 2-phenylpyridine) with the bridging ligand 3,8-dipyridyl-4,7-phenanthroline (L) affords, in 94% yield, the cyclometalated iridium dinuclear complex [(ppy)2Ir(mu-L)Ir(ppy)2]2+ (12+) as a mixture of three stereoisomers. This mixture consists of a meso form Delta,Lambda and a racemic form (enantiomeric pair Delta,Delta and Lambda,Lambda) in the ratio 1:1.5. Single-crystal X-ray characterization of the perchlorate salt of the meso form reveals (i) the distortion of the bridging ligand from the planarity and (ii) the location of the two iridium subunits above and below the medium plane of the bridging ligand. Ion-pair chromatography with Delta-TRISPHAT anion (TRISPHAT = tris(tetrachlorobenzenediolato)phosphate(V)) as resolving anion permits the separation of the three stereoisomers. The 1H NMR spectroscopic analysis of each fraction indicates high diastereomeric purity. Electronic circular dichroism properties and comparison with literature data establish their absolute configuration. The absorption and emission properties of the three stereoisomers show only very small variations. The anisotropic properties can be interpreted as distinct interactions of the isomers with the chiral resolving Delta-TRISPHAT anion. PMID:17636895

Auffrant, Audrey; Barbieri, Andrea; Barigelletti, Francesco; Lacour, Jérôme; Mobian, Pierre; Collin, Jean-Paul; Sauvage, Jean-Pierre; Ventura, Barbara

2007-08-20

210

Electrogenic 2 Na+/1 H+ exchange in crustaceans.  

PubMed

Hepatopancreatic brush border membrane vesicles of the freshwater prawn, Macrobrachium rosenbergii and the marine lobster, Homarus americanus exhibited 22Na uptake which was Cl-independent, amiloride sensitive, and stimulated by a transmembrane H gradient (Hi greater than Ho). Sodium influx by vesicles of both species were sigmoidal functions of [Na]o, yielding Hill coefficients that were not significantly different (P greater than 0.5) than 2.0. Estimations of half-saturation constants (KNa) were 82.2 mM (prawn) and 280.1 mM (lobster), suggesting a possible adaptation of this transporter to environmental salinity. Trans-stimulation and cis-inhibition experiments involving variable [H] suggested that the exchangers in both species possessed single internal cation binding sites (pK 6.5-6.7) and two external cation binding sites (prawn, pK 4.0 and 5.7; lobster pK 3.5 and 6.1). Similar cis inhibition studies using amiloride as a competitive inhibitor of Na uptake supported the occurrence of dual external sites (prawn, Ki50 and 1520 microM; lobster Ki9 and 340 microM). Electrogenic Na/H exchange by vesicles from both crustaceans was demonstrated using equilibrium shift experiments where a transmembrane potential was used as the only driving force for the transport event. Transport stoichiometries of the antiporters were determined using Static Head analysis where driving forces for cation transfer were balanced using a 10:1 Na gradient, a 100:1 H gradient, and a stoichiometry of 2.0. These electrogenic 2 Na/1 H exchangers appear thermodynamically capable of generating sufficient gastric acidification for organismic digestive activities. PMID:2167376

Ahearn, G A; Franco, P; Clay, L P

1990-07-01

211

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

212

3-Cyanopyridine-2(1H)-thiones and 3-cyano-2-(methylthio)pyridines in the synthesis of substituted 3-(aminomethyl)pyridines  

Microsoft Academic Search

The reactions of substituted 3-cyanopyridine-2(1H)-thiones and 3-cyano-2-(methylthio)pyridines with lithium aluminum hydride in anhydrous diethyl ether afforded the corresponding 3-aminomethyl derivatives, which were used in the synthesis of the corresponding amides.

A. A. Zubarev; V. K. Zavyalova; V. P. Litvinov

2003-01-01

213

Formal [4+2] annulation of enaminones and cyanomethyl sulfur ylide: one-pot access to polysubstituted pyridin-2(1H)-ones.  

PubMed

A facile and efficient one-pot synthesis of polysubstituted pyridin-2(1H)-ones from readily available enaminones and the cyanomethyl sulfonium bromide salt in the presence of cesium carbonate is developed, and a mechanism involving sequential nucleophilic vinylic substitution (SNV), intramolecular nucleophilic cyclization and dealkylation reactions is proposed. PMID:25349951

Zhang, Qian; Liu, Xu; Xin, Xiaoqing; Zhang, Rui; Liang, Yongjiu; Dong, Dewen

2014-12-18

214

Ammonium chloride-catalyzed one-pot synthesis of 3,4-dihydropyrimidin-2-(1 H)-ones under solvent-free conditions  

Microsoft Academic Search

Ammonium chloride as a very inexpensive and readily available reagent, and efficiently catalyzes one-pot, three component, Biginelli condensation reactions of aldehydes, 1,3-dicarbonyl compounds and urea or thiourea under solvent-free conditions to afford the corresponding 3,4-dihydropyrimidin-2-(1H)-ones in high yields at 100°C.

Ahmad Shaabani; Ayoob Bazgir; Fatemeh Teimouri

2003-01-01

215

Synthesis, characterization and computational study on ethyl 4-(3-Furan-2yl-acryloyl)-3,5-dimethyl-1H-pyrrole-2-carboxylate  

NASA Astrophysics Data System (ADS)

As part of study on pyrrole derivatives, we have synthesized a pyrrole chalcone derivative: ethyl 4-(3-Furan-2yl-acryloyl)-3,5-dimethyl-1H-pyrrole-2-carboxylate (EFADPC) by aldol condensation of ethyl 3, 5-dimethyl-4-actyl-1H-pyrrole-2-carboxylate with furan-2-carbaldehyde in the presence of strong hydroxyl base as catalyst. The product EFADPC has been confirmed by spectroscopic (FT-IR, 1H NMR, and UV-visible) analyses. Quantum chemical calculation also provides good correlation with experimental data. The molecular electrostatic potential surface (MEP), natural bond orbital interactions (NBO), electronic descriptors, quantum theory of atoms' in molecules (QTAIM) and experimental FT-IR spectrum have been used to predict the sites and nature of interactions which indicate that the dimer formation with multiple interactions through Nsbnd H···O and Csbnd H···O. The vibrational analysis shows red shifts in ?Nsbnd H and ?Cdbnd O as result of dimer formation. The binding energy of dimer is calculated as 13.82, 15.24 kcal/mol using DFT, QTAIM analysis, respectively. The result of ellipticity confirms the existence of resonance assisted hydrogen bonds (RAHB) in dimer. The MEP and local reactivity descriptors analyses have been performed and the results indicate that carbonyl carbon and ?-carbon of chalcone frame have been prone to nucleophilic attack and lead to large number of heterocyclic compounds such as oxirane, oxazoles, pyrazoles, pyridines, pyrimidines, and pyran.

Singh, R. N.; Rawat, Poonam; Sahu, Sangeeta

2014-11-01

216

Liver X receptors alpha gene (NR1H3) promoter polymorphisms are associated with systemic lupus erythematosus in Koreans  

PubMed Central

Introduction Liver X receptors are established sensors of lipid and cholesterol homeostasis. Recent studies have reported that these receptors are involved in the regulation of inflammation and immune responses. We attempted to identify single nucleotide polymorphisms (SNPs) of the NR1H3 gene associated with the susceptibility to systemic lupus erythematosus (SLE). Methods SNPs were genotyped using SNaPSHOT assay in 300 Korean patients with SLE and 217 normal controls (NC), and in replication samples (160 SLE patients and 143 NC). Also, the functional effects of NR1H3 gene promoter polymorphisms were analyzed using a luciferase assay, real-time polymerase chain reaction, B cell proliferation assay and an electrophoretic mobility shift assay. Results We identified five polymorphisms: -1851 T?>?C (rs3758673), -1830 T?>?C (rs3758674), -1003 G?>?A (new), -840 C?>?A (rs61896015) and -115 G?>?A (rs12221497). There was a significant and reproducible difference in the -1830 T?>?C, -1003 G?>?A and -115 G?>?A polymorphisms between the SLE and the NC. Luciferase activity of the structure containing -1830 C was less enhanced compared to the structure containing -1830 T in basal, GW3965 and T0901317 treated Hep3B cells (P?=?0.009, P?=?0.034 and P <0.001, respectively). Proliferation of the -1830 TC type was increased compared to the -1830 TT type in basal, GW3965 and T0901317 treated B cells from SLE patients (P?=?0.011, P?=?0.040 and P?=?0.017, respectively). Transcription factor GATA-3 preferentially bound the -1830 T allele in the promoter. Conclusions NR1H3 genetic polymorphisms may be associated with disease susceptibility and clinical manifestations of SLE. Specifically, -1830 T?>?C polymorphism within NR1H3 promoter region may be involved in regulation of NR1H3 expression. PMID:24886807

2014-01-01

217

Hydrogen on unsupported ruthenium sulfide: Thermodesorption and [sup 1]H NMR studies  

SciTech Connect

The interaction of transition metal sulfides with hydrogen is a complex process. Understanding this process is important due to the very large number of industrial processes dealing with these systems. The main utilization of these catalysts concerns catalytic hydrotreating which involves hydrogenation reactions and C-S, C-N, and C-O bond cleavage reactions carried out in the presence of high partial pressures of hydrogen. The complexity of the interaction of hydrogen with metal sulfides is related to its double role, as reactant and as modifier of the concentration of active sites. As a matter of fact, the interaction of hydrogen with the surface of the catalyst provokes its partial reduction, leading to coordinatively unsaturated metal ions which are directly involved in the adsorptive and catalytic properties. To tackle this fundamental problem of hydrogen adsorption on ruthenium sulfide, the authors have taken the fully sulfided state as starting point and evaluated the influence of progressive desulfurization on the amount of adsorbed hydrogen. The nature of the adsorbed species was investigated using thermodesorption and [sup 1]H NMR. 20 refs., 3 figs.

Lacroix, M.; Yuan, S.; Breysse, M. (Institut de Recherches sur la Catalyse, Villeurbanne (France)); Doremieux-Morin, C.; Fraissard, J. (Universite Piere et Marie Curie, Paris (France))

1992-11-01

218

Detection of IR target by fusing multispectral IR data  

NASA Astrophysics Data System (ADS)

Detection of the small target in clutter, usually regarded as singular points in the infrared image, is an important issue in infrared searching and tracking (IRST) system. Because of the far range of the target to the sensor, the stealth technology, the effects of inherent sensor noise and the phenomena of nature, the target is more difficult to be detected. Multispectral sensor system has been proved it could greatly improve detection of the small, hard-to-find targets by multispectral processing techniques (such as sensor or image fusion). Aiming at the problem of multispectral IR Target Detection, a kind method of the multispectral IR target detection is proposed, based on the existed detection systems. In this method, the image registration is done firstly to make the different sensors have a same scene. Then, a fusion rule, named as adaptive weighted voting theory, is developed to combine the target detection results from the different spectral sensors. The adaptive weighted voting theory can give the different weights, based on the different spectral IR characteristics, and these weights decide the detected target is identified as real target or background. The experimental results show that the proposed method can reduce the detection uncertainty and improve the detection performance. Compared with the single spectral detection results and the others fusion detection methods, it can decrease the lost alarm rate and the false alarm rate effectively. The proposed method has been employed in our IR surveillance system, and it is easy to be used in the various circumstances.

Li, Liya; Qi, Meng; Gao, Xuhui

2011-08-01

219

1H NMR Metabolomics Analysis of Glioblastoma Subtypes  

PubMed Central

Glioblastoma multiforme (GBM) is the most common form of malignant glioma, characterized by unpredictable clinical behaviors that suggest distinct molecular subtypes. With the tumor metabolic phenotype being one of the hallmarks of cancer, we have set upon to investigate whether GBMs show differences in their metabolic profiles. 1H NMR analysis was performed on metabolite extracts from a selection of nine glioblastoma cell lines. Analysis was performed directly on spectral data and on relative concentrations of metabolites obtained from spectra using a multivariate regression method developed in this work. Both qualitative and quantitative sample clustering have shown that cell lines can be divided into four groups for which the most significantly different metabolites have been determined. Analysis shows that some of the major cancer metabolic markers (such as choline, lactate, and glutamine) have significantly dissimilar concentrations in different GBM groups. The obtained lists of metabolic markers for subgroups were correlated with gene expression data for the same cell lines. Metabolic analysis generally agrees with gene expression measurements, and in several cases, we have shown in detail how the metabolic results can be correlated with the analysis of gene expression. Combined gene expression and metabolomics analysis have shown differential expression of transporters of metabolic markers in these cells as well as some of the major metabolic pathways leading to accumulation of metabolites. Obtained lists of marker metabolites can be leveraged for subtype determination in glioblastomas. PMID:22528487

Cuperlovic-Culf, Miroslava; Ferguson, Dean; Culf, Adrian; Morin, Pier; Touaibia, Mohamed

2012-01-01

220

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

221

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

222

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 B 1 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

223

A combined experimental and quantum chemical (DFT and AIM) study on molecular structure, spectroscopic properties, NBO and multiple interaction analysis in a novel ethyl 4-[2-(carbamoyl)hydrazinylidene]-3,5-dimethyl-1H-pyrrole-2-carboxylate and its dimer  

NASA Astrophysics Data System (ADS)

In the present paper, a new ethyl 4-[2-(carbamoyl)hydrazinylidene]-3,5-dimethyl-1H-pyrrole-2-carboxylate (3) has been synthesized and characterized by 1H NMR, UV-Visible, FT-IR and Mass spectroscopy. The formation of the compound and its properties have also been evaluated by quantum chemical calculations using density functional theory (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 stabilization energy of various intra and intermolecular interactions in molecular system. The vibrational analysis indicates the formation of dimer in the solid state by intermolecular heteronuclear hydrogen bonding (Nsbnd H⋯O) and the binding energy of dimer is calculated to be 10.40 kcal/mol, using DFT calculations. 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 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; Gupta, V. P.

2013-03-01

224

Synthesis, molecular structure, multiple interactions and chemical reactivity analysis of a novel ethyl 2-cyano-3-[5-(hydrazinooxalyl-hydrazonomethyl)-1H-pyrrol-2-yl]-acrylate and its dimer: A combined experimental and theoretical (DFT and QTAIM) approach  

NASA Astrophysics Data System (ADS)

A detailed spectroscopic analyses of a newly synthesized ethyl 2-cyano-3-[5-(hydrazinooxalyl-hydrazonomethyl)-1H-pyrrol-2-yl]-acrylate (3) have been carried out using 1H and 13C NMR, UV-Visible, FT-IR and mass spectroscopic techniques. All the quantum chemical calculations have been carried out using DFT level of theory, B3LYP functional and 6-31G(d,p) as basis set. The 1H and 13C NMR chemical shifts are calculated using gauge including atomic orbitals (GIAOs) approach in DMSO-d6. TD-DFT is used to calculate the energy (E), oscillatory strength (f) and wavelength absorption maxima (?max) of various electronic transitions and their nature within molecule. Natural bond orbital (NBO) analysis is carried out to investigate the various intra and intermolecular interactions in dimer and their corresponding second order stabilization energy (E(2)). A combined theoretical and experimental vibrational analysis confirms the existence of dimer and the binding energy of dimer is calculated as 9.21 kcal/mol using DFT calculations. To determine the energy and nature of different interactions topological parameters at bond critical points (BCPs) have been analyzed by Bader's 'atoms in molecules' (AIMs) theory in detail. Electrophilic charge transfer (ECT) is calculated to investigate the relative electrophilic or nucleophilic behavior of reactant molecules involved in chemical reaction. Global electrophilicity index (? = 5.5836 eV) shows that title molecule (3) is a strong electrophile. The local reactivity descriptors such as Fukui functions (fk+,fk-), local softness (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

2013-04-01

225

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

226

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

2012-06-15

227

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  

NASA Astrophysics Data System (ADS)

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, 1H 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 1H 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 (?2?BCP), kinetic electron energy density (GBCP), potential electron density (VBCP) and the total electron energy density (HBCP) 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 (fk+, fk-), local softnesses (sk-, sk+) 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).

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

228

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.  

PubMed

In the present work, ethyl-4-[2-(thiocarbamoyl)hydrazinylidene]-3,5-dimethyl-1H-pyrrole-2-carboxylate (3) has been synthesized and characterized by (1)H 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. (1)H 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 (NH···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 (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. PMID:23666353

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

2013-08-01

229

Spectroscopic and structural study of some 2,5-hexanedione bis(salicyloylhydrazone) complexes: crystal structures of its Ni(II) and Cu(II) complexes and N-(2,5-dimethyl-1H-pyrrol-1-yl)-2-hydroxy-benzamide.  

PubMed

The reaction between 2,5-hexanedione and salicylic acid hydrazide produced two compounds: 2,5-hexanedione bis(salicyloylhydrazone) [HDSH] (ethanol insoluble) and N-(2,5-dimethyl-1H-pyrrol-1-yl)-2-hydroxybenzamide [DPH] (ethanol soluble). HDSH formed complexes with Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Hg(II) and Pd(II) which are characterized by elemental analyses, spectra (IR, (1)H NMR, ESR and MS), thermal and magnetic measurements. The crystals of [Ni(HDSH-2H)(EtOH)(H2O)] and [Cu(HDSH-2H)] were solved having octahedral and square-planar geometries, respectively. The other complexes have the formulae [Co(HDSH-2H)(H2O)2], [Cu(HDSH-H)2], [Zn(HDSH-2H)(H2O)2], [Cd2(HDSH-4H)(H2O)4], [Cd2(HDSH-2H)(H2O)4Cl2]; [Hg(HDSH-2H)] and [Pd2(HDSH-4H)(H2O)4]. The obtained complexes are stable in air and non-hygroscopic. The magnetic moments and electronic spectra of the complexes provide different geometries. The ESR spectra support the mononuclear geometry for [Cu(HDSH-2H)] and [Cu(HDSH-H)2]. The thermal decomposition of the complexes revealed the coordinated waters as well as the end product which is in most cases the metal oxide. The crystal structure of N-(2,5-dimethyl-1H-pyrrol-1-yl)-2-hydroxybenzamide is solved by X-ray technique. PMID:24747853

Jeragh, Bakir; El-Asmy, Ahmed A

2014-08-14

230

Spectroscopic and structural study of some 2,5-hexanedione bis(salicyloylhydrazone) complexes: Crystal structures of its Ni(II) and Cu(II) complexes and N-(2,5-dimethyl-1H-pyrrol-1-yl)-2-hydroxy-benzamide  

NASA Astrophysics Data System (ADS)

The reaction between 2,5-hexanedione and salicylic acid hydrazide produced two compounds: 2,5-hexanedione bis(salicyloylhydrazone) [HDSH] (ethanol insoluble) and N-(2,5-dimethyl-1H-pyrrol-1-yl)-2-hydroxybenzamide [DPH] (ethanol soluble). HDSH formed complexes with Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Hg(II) and Pd(II) which are characterized by elemental analyses, spectra (IR, 1H NMR, ESR and MS), thermal and magnetic measurements. The crystals of [Ni(HDSH-2H)(EtOH)(H2O)] and [Cu(HDSH-2H)] were solved having octahedral and square-planar geometries, respectively. The other complexes have the formulae [Co(HDSH-2H)(H2O)2], [Cu(HDSH-H)2], [Zn(HDSH-2H)(H2O)2], [Cd2(HDSH-4H)(H2O)4], [Cd2(HDSH-2H)(H2O)4Cl2]; [Hg(HDSH-2H)] and [Pd2(HDSH-4H)(H2O)4]. The obtained complexes are stable in air and non-hygroscopic. The magnetic moments and electronic spectra of the complexes provide different geometries. The ESR spectra support the mononuclear geometry for [Cu(HDSH-2H)] and [Cu(HDSH-H)2]. The thermal decomposition of the complexes revealed the coordinated waters as well as the end product which is in most cases the metal oxide. The crystal structure of N-(2,5-dimethyl-1H-pyrrol-1-yl)-2-hydroxybenzamide is solved by X-ray technique.

Jeragh, Bakir; El-Asmy, Ahmed A.

2014-08-01

231

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

232

Dynamic metabolites profile of cerebral ischemia/reperfusion revealed by (1)H NMR-based metabolomics contributes to potential biomarkers.  

PubMed

Current metabolomic studies of ischemic brain mainly attach importance on a certain ischemic period, are lack of data about dynamic metabolites in ischemic stroke process, especially early period. Thus, in this study, (1)H NMR spectroscopy was used to investigate biochemical changes in the early stages of rats' focal cerebral ischemia reperfusion (I/R) injury. Serum samples of 0, 0.5, 1, 3, 6, 12, 24 h of reperfusion, based on multivariate data analyses, were tested to analyze the changing of metabolites during the early disease process. Partial least squares-discriminant analysis scores plots of the (1)H NMR data revealed clear differences among the experiment groups. Combination the results of loading plot and t-test, we found that 13 metabolites were changed significantly. Among that, malonic acid and glycine are the most noticeable variable metabolites. Dramatic changed malonic acid and glycine most probably served as biomarkers in this study. These findings help us understand the biochemical metabolite changes in early ischemic stroke stages, especially different periods. That may be conducive to distinguish at-risk individuals, benefit early diagnosis and understand the dynamic pathogenesis of early cerebral ischemia. PMID:25120785

Wang, Yun; Wang, Yi-Gang; Ma, Teng-Fei; Li, Mei; Gu, Shu-Ling

2014-01-01

233

Dynamic metabolites profile of cerebral ischemia/reperfusion revealed by 1H NMR-based metabolomics contributes to potential biomarkers  

PubMed Central

Current metabolomic studies of ischemic brain mainly attach importance on a certain ischemic period, are lack of data about dynamic metabolites in ischemic stroke process, especially early period. Thus, in this study, 1H NMR spectroscopy was used to investigate biochemical changes in the early stages of rats’ focal cerebral ischemia reperfusion (I/R) injury. Serum samples of 0, 0.5, 1, 3, 6, 12, 24 h of reperfusion, based on multivariate data analyses, were tested to analyze the changing of metabolites during the early disease process. Partial least squares-discriminant analysis scores plots of the 1H NMR data revealed clear differences among the experiment groups. Combination the results of loading plot and t-test, we found that 13 metabolites were changed significantly. Among that, malonic acid and glycine are the most noticeable variable metabolites. Dramatic changed malonic acid and glycine most probably served as biomarkers in this study. These findings help us understand the biochemical metabolite changes in early ischemic stroke stages, especially different periods. That may be conducive to distinguish at-risk individuals, benefit early diagnosis and understand the dynamic pathogenesis of early cerebral ischemia. PMID:25120785

Wang, Yun; Wang, Yi-Gang; Ma, Teng-Fei; Li, Mei; Gu, Shu-Ling

2014-01-01

234

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

235

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...

236

PREDICTION OF REGIONAL WIND POWER T.S. Nielsen1, H. Madsen1, H. Aa. Nielsen1, L. Landberg2, G. Giebel2  

E-print Network

PREDICTION OF REGIONAL WIND POWER T.S. Nielsen1, H. Madsen1, H. Aa. Nielsen1, L. Landberg2, G the total wind power production in a larger region based on a combination of on-line measurements of power ­ an on-line software system for calculating short-term pre- dictions of wind power currently being

237

A theoretical comparison of the chemical shifts of three related heterocycles: 1 H-pyrazoles, 1 H-1,2,4-triazoles and 1 H-1,2,4-diazaphospholes  

Microsoft Academic Search

Seventeen derivatives of 1H-pyrazoles, 1H-1,2,4-triazoles and 1H-1,2,4-diazaphospholes (three of them existing in two tautomeric forms, thus forming 20 families of compounds) were studied theoretically. At the GIAO\\/B3LYP\\/6-311++G(d,p) level, the calculations reproduce fairly well the available experimental chemical shifts. The completeness of the calculated absolute shieldings allows to discuss the relationships between the 4-position (CH, C, N and P) chemical shifts.

Ibon Alkorta; Fernando Blanco; José Elguero

2010-01-01

238

Vibrational spectroscopic, 1H NMR and quantum chemical computational study of 4-hydroxy-2-oxo-1,2-dihydroquinoline-8-carboxylic acid.  

PubMed

FT-IR, FT-Raman and (1)H NMR spectra of 4-hydroxy-2-oxo-1,2-dihydroquinoline-8-carboxylic acid were recorded and obtained data were confronted with the computed using Gaussian09 software package. DFT/B3LYP, B3PW91 calculations have been done using 6-31G* and SDD basis sets, to investigate the vibrational frequencies and geometrical parameters. The assignments of the normal modes are done by potential energy distribution (PED) calculations. The calculated first hyperpolarizability is comparable with the reported values of similar quinoline derivatives and is an attractive object for future studies of non-linear optics. The stability of the molecule arising from hyperconjugative interaction and charge delocalization has been analyzed using NBO analysis. MEP predicts the most reactive part in the molecule. The calculated (1)H NMR results are in good agreement with experimental data. PMID:24287054

Ulahannan, Rajeev T; Panicker, C Yohannan; Varghese, Hema Tresa; Van Alsenoy, C; Musiol, Robert; Jampilek, Josef; Anto, P L

2014-01-01

239

Synthesis and biological evaluation of novel N-substituted 1H-dibenzo[a,c]carbazole derivatives of dehydroabietic acid as potential antimicrobial agents.  

PubMed

A series of new N-substituted 1H-dibenzo[a,c]carbazole derivatives were synthesized from dehydroabietic acid, and their structures were characterized by IR, (1)H NMR and HRMS spectral data. All compounds were evaluated for their antibacterial and antifungal activities against four bacteria (Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas fluorescens) and three fungi (Candida albicans, Candida tropicalis and Aspergillus niger) by serial dilution technique. Some of the synthesized compounds displayed pronounced antimicrobial activity against tested strains with low MIC values ranging from 0.9 to 15.6?g/ml. Among them, compounds 6j and 6r exhibited potent inhibitory activity comparable to reference drugs amikacin and ketoconazole. PMID:24300736

Gu, Wen; Qiao, Chao; Wang, Shi-Fa; Hao, Yun; Miao, Ting-Ting

2014-01-01

240

Isomeric luminescent Zn(II) coordination polymers based on pyridinecarboxylate and 5-methyl-1H-tetrazole ligands  

NASA Astrophysics Data System (ADS)

Two new metal-organic frameworks, namely [Zn(nic)(mtz)]n (1) and [Zn(isonic)(mtz)]n (2) (Hnic = nicotinic acid, Hisonic = isonicotinic acid, Hmtz = 5-methyl-1H-tetrazole), have been obtained through the solvothermal reactions of Zn(NO3)2, Htmz and Hnic or Hisonic. Single crystal X-ray diffraction analysis reveals that compound 1 features a 2D layered structure with sql topology, which is further extended into a 3D supramolecular framework via weak CH…? interactions, and compound 2 is 2-fold interpenetrated 3D framework with dia topology. Luminescent investigation shows that both of them emit blue luminescence at room temperature.

An, Zhe; Gao, Jing; Zhu, Ling

2013-12-01

241

Reductive opening of 1 H,3 H-benzo[ de]isochromene: synthesis of 1,8-difunctionalised naphthalenes  

Microsoft Academic Search

The lithiation of 1H,3H-benzo[de]isochromene (6) with lithium and a catalytic amount of 4,4?-di-tert-butylbiphenyl (DTBB, 5% molar) in THF at ?50 °C gives dianionic intermediate 7, which by reaction with different electrophiles {H2O, D2O, tBuCHO, PhCHO, Me2CO, (CH3CH2)2CO, [CH3(CH2)4]2CO, (CH2)5CO, (CH2)7CO, (?)-menthone} at the same temperature followed by hydrolysis leads to functionalised alcohols 8. If after addition of a carbonyl compound

Francisco Foubelo; Benjam??n Moreno; Miguel Yus

2004-01-01

242

[Identification of the metabolites of an antiallergic agent, 1-(2-ethoxyethyl)-2-(hexahydro-4-methyl-1H-1,4-diazepine-1-yl)-1H- benzimidazole difumarate (KG-2413), in rats].  

PubMed

The urinary and biliary metabolites of a new antiallergic agent, 1-(2-ethoxyethyl)-2-(hexahydro-4-methyl-1H-1,4-diazepine-1-yl)-1H-b enzimidazole difumarate (KG-2413) in rats were identified by using a 14C-labelled drug and instrumental analyses, e.g., high performance liquid chromatography, gas chromatography (GC), 1H nuclear magnetic resonance, mass spectrometry (MS) and GC/MS. A slight amount of KG-2413 free base was detected only in the unconjugated fraction of urine. The main pathways of biotransformation of KG-2413 in rats were: (a) aromatic hydroxylation in the benzimidazole ring, (b) N-oxidation and N-demethylation in the 1,4-diazepine ring, (c) alpha-carbon oxidation (lactam formation) in the 1,4-diazepine ring (d) O-deethylation in the N-ethoxyethyl side chain. Regioselectivity was observed for aromatic hydroxylation, as only two of the four possible monohydroxylated metabolites could be detected. Furthermore, N-oxidation and lactam formation reactions were found to be regiospecific, that is, the former took place only at the position of 4-N atom and the latter at 5-C atom, respectively. PMID:2576283

Awata, N; Takahashi, H; Noumi, K; Sakai, T; Hamada, T

1989-05-01

243

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

244

Anion-directed assembly of two novel cadmium(II) complexes constructed by 2,2?-(1,4-butanediyl)bis(1 H-benzimidazole) ligand  

Microsoft Academic Search

Depending on the different coordinated anions used, reaction of Cd(II) salt with 2,2?-(1,4-butanediyl)bis(1H-benzimidazole) results in the formation of two coordination polymers: a 1D chain {[Cd(H2C4BIm)Cl2]·(H2C4BIm)}n (1), and a 2D sheet [Cd(HC4BIm)(NCS)]n (2) which features distorted 4.82 topology (H2C4BIm=2,2?-(1,4-butanediyl)bis(1H-benzimidazole)). The fluorescence properties for both the complexes have been studied.

Yong Wang; Hong-Bin Xu; Zhong-Min Su; Kui-Zhan Shao; Ya-Hui Zhao; Hong-Peng Cui; Ya-Qian Lan; Xiang-Rong Hao

2006-01-01

245

Simple Approaches for Estimating Vicinal 1H- 1H Coupling-Constants and for Obtaining Stereospecific Resonance Assignments in Leucine Side Chains  

NASA Astrophysics Data System (ADS)

An approach for deriving stereospecific ?-methyl assignments and ? 2 dihedral angle constraints for leucine residues, based on easily recognized patterns of 1H- 1H spin-spin coupling constants and intraresidue nuclear-Overhauser-effect spectroscopy (NOESY) cross-peak intensities, is described. The approach depends on resolved H ? and/or ?-methyl resonances and on initially obtaining stereospecific assignments for H ?2 and H ?3. As part of the overall strategy, a method is presented for obtaining qualitative or, in favorable cases, semiquantitative estimates of vicinal 1H- 1H coupling constants from peak intensities measured in a short-mixing-time 1H- 1H total correlation spectroscopy (TOCSY) experiment. This method of estimating 1H- 1H spin-spin coupling constants is generally applicable to all side-chain types. The approach is illustrated for several leucine residues within uniformly 15N-labeled and 15N/ 13C-double-labeled isolated light-chain variable domain of the anti-digoxin antibody 26-10. Estimates of 3J?? and 3J?? coupling constants are derived from a three-dimensional (3D) 13C-edited TOCSY-heteronuclear multiple-quantum coherence (HMQC) spectrum. These data are combined with information from 3D 15N-edited NOESY and 3D 13C-edited NOESY spectra to yield stereospecific H ?2, H ?3, and ?-methyl assignments, as well as constraints on ? (1) and ? 2 dihedral angles. Although the overall approach is illustrated using 3D 15N-edited and 13C-edited data, it is equally applicable to analysis of two-dimensional 1H- 1H NOESY and TOCSY spectra.

Constantine, K. L.; Friedrichs, M. S.; Mueller, L.

246

IrII(ethene): metal or carbon radical?  

PubMed

One-electron oxidation of [(Me(n)tpa)Ir(I)(ethene)]+ complexes (Me(3)tpa = N,N,N-tri(6-methyl-2-pyridylmethyl)amine; Me(2)tpa = N-(2-pyridylmethyl)-N,N,-di[(6-methyl-2-pyridyl)methyl]-amine) results in relatively stable, five-coordinate Ir(II)-olefin species [(Me(n)tpa)Ir(II)(ethene)](2+) (1(2+): n = 3; 2(2+): n = 2). These contain a "vacant site" at iridium and a "non-innocent" ethene fragment, allowing radical type addition reactions at both the metal and the ethene ligand. The balance between metal- and ligand-centered radical behavior is influenced by the donor capacity of the solvent. In weakly coordinating solvents, 1(2+) and 2(2+) behave as moderately reactive metallo-radicals. Radical coupling of 1(2+) with NO in acetone occurs at the metal, resulting in dissociation of ethene and formation of the stable nitrosyl complex [(Me(3)tpa)Ir(NO)](2+) (6(2+)). In the coordinating solvent MeCN, 1(2+) generates more reactive radicals; [(Me(3)tpa)Ir(MeCN)(ethene)](2+) (9(2+)) by MeCN coordination, and [(Me(3)tpa)Ir(II)(MeCN)](2+) (10(2+)) by substitution of MeCN for ethene. Complex 10(2+) is a metallo-radical, like 1(2+) but more reactive. DFT calculations indicate that 9(2+) is intermediate between the slipped-olefin Ir(II)(CH(2)=CH(2)) and ethyl radical Ir(III)-CH(2)-CH(2). resonance structures, of which the latter prevails. The ethyl radical character of 9(2+) allows radical type addition reactions at the ethene ligand. Complex 2(2+) behaves similarly in MeCN. In the absence of further reagents, 1(2+) and 2(2+) convert to the ethylene bridged species [(Me(n)tpa)(MeCN)Ir(III)(mu(2)-C(2)H(4))Ir(III)(MeCN)(Me(3)tpa)](4+) (n = 3: 3(4+); n = 2: 4(4+)) in MeCN. In the presence of TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxo), formation of 3(4+) from 1(2+) in MeCN is completely suppressed and only [(Me(3)tpa)Ir(III)(TEMPO(-))(MeCN)](2+) (7(2+)) is formed. This is thought to proceed via radical coupling of TEMPO at the metal center of 10(2+). In the presence of water, hydrolysis of the coordinated acetonitrile fragment of 7(2+) results in the acetamido complex [(Me(3)tpa)Ir(III)(NHC(O)CH(3)))(TEMPOH)](2+) (8(2+)). PMID:15701024

Hetterscheid, Dennis G H; Kaiser, Jasper; Reijerse, Eduard; Peters, Theo P J; Thewissen, Simone; Blok, Arno N J; Smits, Jan M M; de Gelder, René; de Bruin, Bas

2005-02-16

247

A novel immunosuppressant, IR-1116, which has a different biological mechanism from that of cyclosporine A.  

PubMed

The effects of an epifumagillol derivative, IR-1116, on human lymphocytes in vitro, mouse antibody production in vivo and rat renal and cardiac transplantation were investigated. IR-1116 suppressed the human primary mixed lymphocyte reaction (MLR) in a dose-dependent manner with a value of the dose required for 50% suppression of 0.32 microM. IR-1116 suppressed the antibody production by human B lymphocytes activated with pokeweed mitogen or Epstein-Barr virus, but did not affect the interleukin-2 production by human lymphocytes stimulated with phytohemagglutinin. Furthermore, IR-1116 did not have any effect on the proliferation of B or T lymphocytes. IR-1116 is thought to have a different mechanism from cyclosporine A (CsA). BALB/c mice were immunized by s.c. injection of bovine gamma-globulin (BGG) and then received IR-1116 or CsA by i.p. injection at a dose of 20 mg/kg every other day for 2 weeks. IR-1116 suppressed the production of serum antibodies against BGG as strongly as CsA. In this experiment, IR-1116 apparently showed no adverse effects, while CsA-treated mice suffered from diarrhea and appeared to be irritated. Histological studies showed that IR-1116 suppressed the formation of germinal centers in the spleen of immunized mice. Flow cytometric analysis showed that IR-1116 caused a reduction of B lymphocyte population in splenocytes. On the other hand, CsA caused a marked reduction of helper T lymphocyte population in splenocytes and thymocytes. Furthermore, the i.p. administration of IR-1116 prolonged the survival time in a rat renal allograft model and the vital period of grafted hearts in rats. Based on the above, IR-1116 seems to be a new type of immunosuppressant acting via novel mechanisms different from those of immunosuppressants such as CsA, a potent T lymphocyte suppressant. PMID:8370395

Matsumoto, S; Marui, S; Shiho, O; Tsukamoto, K; Yoshimura, N; Oka, T

1993-09-01

248

Syntheses, Crystal Structures, and Fluorescent Properties of Three Complexes Based on 1-((Benzotriazol-1-yl)methyl)-1-H-1,3-imdazole  

Microsoft Academic Search

Three new complexes formulated as [Zn(bmi)2Cl2] (1), [Zn(bmi)2(N3)2](2), and [Hg(bmi)Cl2]2 (3) (bmi = 1-((benzotriazol-1-yl)methyl)-1-H-1,3-imdazole) have been synthesized and characterized by elemental analysis, IR and single crystal X-ray diffraction. Complexes 1 and 2 show mononuclear structures, and complex 3 exhibits binuclear structure. In the solid state, they all possess a three-dimensional network formed by hydrogen bonds and ?-? interactions. Their fluorescent

Likun Duan; Shuangliang Liu; Wan Zhou; Xiangru Meng

2010-01-01

249

Synthesis of 2-aryl-4-(4- ? -D-allopyranosyloxyphenyl)4,6,7,8-tetrahydroquinolin-5(1 H )-one derivatives under solvent-free conditions and study of sedative activity  

Microsoft Academic Search

Under solvent-free conditions, syntheses of 2-aryl-4-(4-?-D-allopyranosyloxyphenyl)-4,6,7,8tetrahydroquinolin-5(1H)-one derivatives were carried out from chalcone (2a–2e), cyclohexane-1,3-dione (3), and NH4OAc in excellent yield without using any catalysts. The structure of the new compounds were characterized by 1H NMR, IR, and HR-MS spectroscopy. The preliminary bioassay tests of 4a–4j indicated that compounds 4b, 4e, and 4f exhibited potent sedative and hypnotic activity.

Congling Yang; Shiming Lv; Ying Li; Shufan Yin

2011-01-01

250

Synthesis and evaluation of substituted 5-(3-chloro-2-oxo-4-phenylazetidin-1-ylamino)pyrimidine-2,4,6(1 H ,3 H ,5 H )-triones against pentylenetetrazole-induced convulsant in mice  

Microsoft Academic Search

This study was designed to synthesis of substituted 5-(3-chloro-2-oxo-4-phenylazetidin-1-ylamino)pyrimidine-2,4,6(1H,3H,5H)-triones followed by evaluation against pentylenetetrazole-(PTZ) induced convulsant in mice. The titled compounds were confirmed\\u000a by IR and 1H-NMR spectral techniques. Pre-treatment of compound 4c showed significant anticonvulsant activity at 40 mg\\/kg which was comparable to that of PTZ and sodium valproate pre-treated\\u000a groups. The results show the importance of barbituric acid derivative

Karan Deep Singh Puri; Shailja Sood; Arunachalam Muthuraman

251

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

252

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

253

Broadband IR transparent rain erosion protective coating for IR windows  

Microsoft Academic Search

Texas Instruments (TI) has an ongoing development effort for protective coatings to enhance the environmental durability, particularly against water and particle impact, of infrared (IR) (8 to 12 micrometers ) transmissive windows and domes on airborne platforms. This program has produced a very effective, rain-erosion-resistant coating consisting of polycrystalline or epitaxial gallium phosphide (GaP). The GaP coating has been grown

Paul Klocek; James T. Hoggins; Michael Wilson

1992-01-01

254

Broadband IR transparent rain erosion protective coating for IR windows  

NASA Astrophysics Data System (ADS)

Texas Instruments (TI) has an ongoing development effort for protective coatings to enhance the environmental durability, particularly against water and particle impact, of infrared (IR) (8 to 12 micrometers ) transmissive windows and domes on airborne platforms. This program has produced a very effective, rain-erosion-resistant coating consisting of polycrystalline or epitaxial gallium phosphide (GaP). The GaP coating has been grown on germanium (Ge), gallium arsenide (GaAs), and zinc sulfide (ZnS) window/dome materials using a metal-organic chemical vapor deposition (MOCVD) process. The coatings have low IR absorption coefficients of 2 cm-1 at 10.6-micrometers wavelength, as measured by laser calorimetry. At a thickness of 20 micrometers , these GaP coatings degrade the transmission of the window/dome materials by only 1 percent. These high-transmission coatings have been shown to be very effective in protecting the window/dome materials from rain impact damage, as evidenced in testing by single-waterdrop impact, multiple-impact jet apparatus and whirling arm rain erosion. The details of the properties of these GaP IR protective coatings are presented and discussed.

Klocek, Paul; Hoggins, James T.; Wilson, Michael

1992-12-01

255

Ibogaino ir noribogaino pasiskirstymas peli? organuose.  

E-print Network

??Darbo tikslas: Nustatyti ibogaino ir noribogaino pasiskirstym? peli? organuose. Darbo uždaviniai: atlikti mokslin?s literat?ros apžvalg?. Pasirinkti tyrimo metodik? ir j? pritaikyti ibogaino, noribogaino pasiskirstymo nustatymui… (more)

Marksa,; Mindaugas

2011-01-01

256

Introduction Basic XML concepts Challenges in XML IR Vector space model for XML IR Evaluation of XML IR Web Search and Text Mining  

E-print Network

Introduction Basic XML concepts Challenges in XML IR Vector space model for XML IR Evaluation of XML IR Web Search and Text Mining http://www.cc.gatech.edu/~agray/6240spr11 IIR 10: XML Retrieval;Introduction Basic XML concepts Challenges in XML IR Vector space model for XML IR Evaluation of XML IR

Gray, Alexander

257

A Carbene-Rich but Carbonyl-Poor [Ir6 (IMe)8 (CO)2 H14 ](2+) Polyhydride Cluster as a Deactivation Product from Catalytic Glycerol Dehydrogenation.  

PubMed

The title cluster, a deactivation product in the catalytic dehydrogenation of glycerol, was characterized by XRD, DFT calculations, HRMS, FTIR spectroscopy, and NMR spectroscopy. Experimental/computational studies located the 14 H ligands, and all (1) H and (13) C{(1) H} NMR resonances were assigned. The structure contains an unprecedented Ir6 H14 core with two CO and eight IMe ligands. PMID:25252028

Campos, Jesús; Sharninghausen, Liam S; Crabtree, Robert H; Balcells, David

2014-11-17

258

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

2013-02-01

259

Mechanism of inhibition of H+, K(+)-ATPase by sodium 2-[[4-(3- methoxypropoxy)-3-methylpyridin-2-yl]methylsulfinyl]-1H-benzimidazole (E3810).  

PubMed

Sodium 2-[[4-(3-methoxypropoxy)-3-methylpyridin-2-yl]methylsulfinyl ]- 1H-benzimidazole (E3810) and omeprazole inhibit gastric acid secretion through inhibition of the activity of H+, K(+)-ATPase present in parietal cell membrane vesicles, by chemical modification of SH groups in the enzyme molecule. In order to clarify the mechanism of the chemical modification, reaction products of E3810 and omeprazole with 2-mercaptoethanol under acidic conditions (pH 3, 4, 5, 6) were isolated by HPLC, and subjected to structural analysis by UV, 1H-NMR and mass spectrometry. E3810 and omeprazole appeared to undergo two kinds of reactions, affording disulfide-type products (type I reaction) and sulfide-type products (type II reaction). The rates of these reactions were determined by HPLC, and the stability of the products in the presence and absence of glutathione was investigated. In the case of E3810, type I reaction was found to proceed faster than type II reaction at every pH value studied. The type I reaction of E3810 was faster than that of omeprazole. The rate of type I reaction decreased at pH 5 and 6, especially for omeprazole, and the contribution of type II reaction increased as the pH of the reaction mixture was increased. The sulfide-type modification products were stable, whereas the formation of the disulfide-type modification products was reversed by the action of endogenous SH compounds such as glutathione. These results suggest that higher inhibitory activity of E3810 against gastric acid secretion and faster recovery of the enzyme activity after inhibition by E3810 can be expected, as compared with those of omeprazole. PMID:8882453

Nochi, S; Yokoyama, Y; Narukawa, M; Ebine, K; Murahashi, M; Kawakami, Y; Asakawa, N; Sato, T

1996-03-01

260

Using Graded Relevance Assessments in IR Evaluation.  

ERIC Educational Resources Information Center

Proposes evaluation methods based on the use of nondichotomous relevance judgements in information retrieval (IR) experiments. Argues that evaluation methods should credit IR methods for their ability to retrieve highly relevant documents. This is desirable from the user point of view in modern large IR environments. (Author/AEF)

Kekalalainen, Jaana; Jarvelin, Kalervo

2002-01-01

261

Ultrafast 2D IR Vibrational Echo Spectroscopy  

E-print Network

Ultrafast 2D IR Vibrational Echo Spectroscopy JUNRONG ZHENG, KYUNGWON KWAK, AND M. D. FAYER The experimental technique and applications of ultrafast two- dimensional infrared (2D IR) vibrational echo systems. The form and time evolution of the 2D IR spectrum permits examination of processes that cannot

Fayer, Michael D.

262

Using graded relevance assessments in IR evaluation  

Microsoft Academic Search

This paper proposes evaluation methods based on the use of non-dichotomous relevance judgements in IR experi- ments. It is argued that evaluation methods should credit IR methods for their ability to retrieve highly relevant documents. This is desirable from the user point of view in modern large IR environments. The proposed methods are (1) a novel application of P-R curves

Jaana Kekäläinen; Kalervo Järvelin

2002-01-01

263

Nonlinear-optic IR radiation converters  

NASA Astrophysics Data System (ADS)

A new class of instruments, nonlinear-optic (parametric) IR-visible converters, is described. A geometrical optics approximation and the diffraction theory are presented, and an analysis is made of the converter efficiency, noise characteristics, and threshold sensitivity of IR nonlinear-optic IR detection schemes. The theoretically derived converter parameters are compared with experimental data.

Gainer, Aleksandr V.

264

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

PubMed

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. PMID:21647324

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

2011-01-01

265

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. PMID:21647324

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

2011-01-01

266

Decreased insulin clearance in individuals with elevated 1-h post-load plasma glucose levels.  

PubMed

Reduced insulin clearance has been shown to predict the development of type 2 diabetes. Recently, it has been suggested that plasma glucose concentrations ? 8.6 mmol/l (155 mg/dl) at 1 h during an oral glucose tolerance test (OGTT) can identify individuals at high risk for type 2 diabetes among those who have normal glucose tolerance (NGT 1 h-high). The aim of this study was to examine whether NGT 1 h-high have a decrease in insulin clearance, as compared with NGT individuals with 1-h post-load glucose <8.6 mmol/l (l (155 mg/dl, NGT 1 h-low). To this end, 438 non-diabetic White individuals were subjected to OGTT and euglycemic-hyperinsulinemic clamp to evaluate insulin clearance and insulin sensitivity. As compared with NGT 1 h-low individuals, NGT 1 h-high had significantly higher 1-h and 2-h post-load plasma glucose and 2-h insulin levels as well as higher fasting glucose and insulin levels. NGT 1 h-high exhibited also a significant decrease in both insulin sensitivity (P<0.0001) and insulin clearance (P = 0.006) after adjusting for age, gender, adiposity measures, and insulin sensitivity. The differences in insulin clearance remained significant after adjustment for fasting glucose (P = 0.02) in addition to gender, age, and BMI. In univariate analyses adjusted for gender and age, insulin clearance was inversely correlated with body weight, body mass index, waist, fat mass, 1-h and 2-h post-load glucose levels, fasting, 1-h and 2-h post-load insulin levels, and insulin-stimulated glucose disposal. In conclusion, our data show that NGT 1 h-high have a reduction in insulin clearance as compared with NGT 1 h-low individuals; this suggests that impaired insulin clearance may contribute to sustained fasting and post-meal hyperinsulinemia. PMID:24194886

Marini, Maria Adelaide; Frontoni, Simona; Succurro, Elena; Arturi, Franco; Fiorentino, Teresa Vanessa; Sciacqua, Angela; Hribal, Marta Letizia; Perticone, Francesco; Sesti, Giorgio

2013-01-01

267

Decreased Insulin Clearance in Individuals with Elevated 1-h Post-Load Plasma Glucose Levels  

PubMed Central

Reduced insulin clearance has been shown to predict the development of type 2 diabetes. Recently, it has been suggested that plasma glucose concentrations ?8.6 mmol/l (155 mg/dl) at 1 h during an oral glucose tolerance test (OGTT) can identify individuals at high risk for type 2 diabetes among those who have normal glucose tolerance (NGT 1 h-high). The aim of this study was to examine whether NGT 1 h-high have a decrease in insulin clearance, as compared with NGT individuals with 1-h post-load glucose <8.6 mmol/l (l (155 mg/dl, NGT 1 h-low). To this end, 438 non-diabetic White individuals were subjected to OGTT and euglycemic-hyperinsulinemic clamp to evaluate insulin clearance and insulin sensitivity. As compared with NGT 1 h-low individuals, NGT 1 h-high had significantly higher 1-h and 2-h post-load plasma glucose and 2-h insulin levels as well as higher fasting glucose and insulin levels. NGT 1 h-high exhibited also a significant decrease in both insulin sensitivity (P<0.0001) and insulin clearance (P?=?0.006) after adjusting for age, gender, adiposity measures, and insulin sensitivity. The differences in insulin clearance remained significant after adjustment for fasting glucose (P?=?0.02) in addition to gender, age, and BMI. In univariate analyses adjusted for gender and age, insulin clearance was inversely correlated with body weight, body mass index, waist, fat mass, 1-h and 2-h post-load glucose levels, fasting, 1-h and 2-h post-load insulin levels, and insulin-stimulated glucose disposal. In conclusion, our data show that NGT 1 h-high have a reduction in insulin clearance as compared with NGT 1 h-low individuals; this suggests that impaired insulin clearance may contribute to sustained fasting and post-meal hyperinsulinemia. PMID:24194886

Marini, Maria Adelaide; Frontoni, Simona; Succurro, Elena; Arturi, Franco; Fiorentino, Teresa Vanessa; Sciacqua, Angela; Hribal, Marta Letizia; Perticone, Francesco; Sesti, Giorgio

2013-01-01

268

Irs1 and Irs2 signaling is essential for hepatic glucose homeostasis and systemic growth  

PubMed Central

Insulin receptor substrates, including Irs1 and Irs2, integrate insulin and IGF receptor signals with heterologous pathways to coordinate growth and metabolism. Since Irs2 is thought to be especially important in hepatic nutrient homeostasis, we deleted Irs1 from hepatocytes of WT mice (called LKO) or genetically insulin-resistant Irs1–/– mice (called LKO::Irs1–/–). Viable LKO::Irs1–/– mice were 70% smaller than WT or LKO mice, and 40% smaller than Irs1–/– mice. Hepatic insulin receptors were functional in all the mice, but insulin signaling via the Akt—FoxO1 pathway was reduced in Irs1–/– and LKO liver, and undetected in LKO::Irs1–/– liver; however, Gsk3? phosphorylation (Ser9) and hepatic glycogen stores were nearly normal in all of the mice. LKO and Irs1–/– mice developed insulin resistance and glucose intolerance that never progressed to diabetes, whereas LKO::Irs1–/– mice developed hyperglycemia and hyperinsulinemia immediately after birth. Regardless, few hepatic genes changed expression significantly in Irs1–/– or LKO mice, whereas hundreds of genes changed in LKO::Irs1–/– mice — including elevated levels of Pck1, G6pc, Ppargc1, Pparg, and Igfbp1. Thus, signals delivered by Irs1 or Irs2 regulate hepatic gene expression that coordinates glucose homeostasis and systemic growth. PMID:16374520

Dong, Xiaocheng; Park, Sunmin; Lin, Xueying; Copps, Kyle; Yi, Xianjin; White, Morris F.

2006-01-01

269

What Nonlinear-IR Experiments Can Tell You about Water that the IR Spectrum Cannot  

E-print Network

What Nonlinear-IR Experiments Can Tell You about Water that the IR Spectrum Cannot Ivan R. PileticVersity, Stanford, California 94305 Received April 12, 2006; E-mail: fayer@stanford.edu Infrared (IR) spectroscopy as qualitative depictions of the integrity of the hydrogen bond network.2-4 Here, we use nonlinear-IR

Fayer, Michael D.

270

IR Spectroscopy and Microscopy Beamlines at the CLS CLS-IR-lines.doc (5-Sep00)  

E-print Network

IR Spectroscopy and Microscopy Beamlines at the CLS CLS-IR-lines.doc (5-Sep00) National Coordinator a comprehensive facility to perform spectroscopic experiments using synchrotron IR radiation which will be easily and government. One beamline will be devoted to far-IR and high resolution experiments. It is led by NRC

Hitchcock, Adam P.

271

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. PMID:22532338

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

2012-01-01

272

Effectiveness of novel 5-(5-amino-1-aryl-1H-pyrazol-4-yl)-1H-tetrazole derivatives against promastigotes and amastigotes of Leishmania amazonensis.  

PubMed

In this research, a series of substituted 5-(5-amino-1-aryl-1H-pyrazol-4-yl)-1H-tetrazoles were synthesized and evaluated for in vitro antileishmanial activity. Among the derivatives, examined compounds 3b and 3l exhibited promising activity against promastigotes and amastigotes forms of Leishmania amazonensis. The cytotoxicity of these compounds was evaluated on murine cells, giving access to the corresponding selectivity index (SI). PMID:24119090

dos Santos Faiões, Viviane; Leon, Leonor L; Canto-Cavalheiro, Marilene M; Torres-Santos, Eduardo C; Bernardino, Alice M R; Vegi, Percilene F; dos Santos, Maurício S

2014-03-01

273

Generation of a monoclonal antibody for INI1/hSNF5/BAF47.  

PubMed

INI1/hSNF5/BAF47, which has an SNF5 domain, belongs to the SWI/SNF family. This family is known as ATP-dependent regulators of gene expression by remodeling chromatin structure during cell differentiation. However, the detailed function of INI1/hSNF5/BAF47 is unclear. Here we report the generation of a specific monoclonal antibody for INI1/hSNF5/BAF47 by the mouse iliac lymph node method. The obtained antibody recognized two isoforms of INI1/hSNF5/BAF47 in immunoblotting and precisely recognized the nuclear localization of INI1/hSNF5/BAF47 in immunostaining. This antibody can contribute to further elucidation of the mechanisms of gene expression regulation by INI1/hSNF5/BAF47 during cell differentiation. PMID:24555937

Harada, Akihito; Hayashi, Masayasu; Kuniyoshi, Yuuki; Semba, Yuichiro; Sugahara, Satoko; Tachibana, Taro; Ohkawa, Yasuyuki; Fujita, Masatoshi

2014-02-01

274

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. PMID:23227298

Peng, Chunte Sam; Tokmakoff, Andrei

2012-01-01

275

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

276

Synthesis, Spectral Analysis, In Vitro Microbiological Evaluation, and Molecular Docking Studies of Some Novel 1-(1-Aryl-1H-tetrazol-5-yl)-2-(piperidin-1-yl)ethanone Derivatives.  

PubMed

A new series of novel heterocyclic compounds containing both tetrazoles and piperidine nuclei together, namely, 1-(1-aryl-1H-tetrazol-5-yl)-2-(piperidin-1-yl)ethanone (22-28), were synthesized by the treatment of the respective 2-chloro-1-(1-aryl-1H-tetrazol-5-yl)ethanone (15-21) with piperidine in acetonitrile for 6?h. A series of novel tetrazole substituted piperidine derivatives were synthesized and evaluated for their antimicrobial activity using serial dilution method. The structures of the synthesized compounds were characterized by IR, (1)H NMR, (13)C NMR, mass spectral data, and elemental analysis. Evaluation of antimicrobial activity shows that several compounds exhibit good activity when compared with the reference drug candidates and thus could be promising new lead molecules. PMID:24944827

Elavarasan, Thangasamy; Bhakiaraj, Durairaj Peter; Gopalakrishnan, Mannathusamy

2014-01-01

277

Nucleophilic Substitution of Oxazino-/Oxazolino-/Benzoxazin- [3,2-b]indazoles: An Effective Route to 1 H-Indazolones  

PubMed Central

A variety of nucleophiles – thiolates, alkoxides, amines, iodide, and cyanide – react with oxazino-, oxazolino-, and benzoxazin[3,2-b]indazoles under microwave conditions to yield a diverse set of 2-substituted 1 H-indazolones. The synthetic utility of these indazoles is further demonstrated by ANRORC (Addition of the Nucleophile, Ring Opening, and Ring Closure) reactions to yield isomeric pyrazoloindazolones by a process wherein iodide acts first as a nucleophile and subsequently as a leaving group. PMID:20438102

Donald, Michael B.; Conrad, Wayne E.; Oakdale, James S.; Butler, Jeffrey D.; Haddadin, Makhluf J.; Kurth, Mark J.

2011-01-01

278

Efficient access to (1 H)-isoindolin-1-one-3-carboxylic acid derivatives by orthopalladation and carbonylation of methyl arylglycinate substrates  

Microsoft Academic Search

The orthopalladation of methyl arylglycinate derivatives has been studied. The reaction proceeds efficiently for different electron-withdrawing and electron-releasing substituents at the aryl ring. The carbonylation of the orthopalladated complexes affords, in a single step, substituted (1H)-isoindolin-1-one-3-carboxylates. These compounds constitute valuable synthetic intermediates and can be transformed diastereoselectively into octahydroisoindole-1-carboxylic acid derivatives, an important scaffold in the synthesis of many biologically

Sonia Nieto; Francisco J. Sayago; Pedro Laborda; Tatiana Soler; Carlos Cativiela; Esteban P. Urriolabeitia

2011-01-01

279

Polynorbornene as a low loss matrix material for IR metamaterial applications.  

SciTech Connect

Novel low loss photopatternable matrix materials for IR metamaterial applications were synthesized using the ring opening metathesis polymerization reaction (ROMP) of norbornene followed by a partial hydrogenation to remove most of the IR absorbing olefin groups which absorb in the 8-12 {micro}m range. Photopatterning was achieved via crosslinking of the remaining olefin groups with alpha, omega-dithiols via the thiol-ene coupling reaction. Since ROMP is a living polymerization the molecular weight of the polymer can be controlled simply by varying the ratio of catalyst to monomer. In order to determine the optimum photopattenable IR matrix material we varied the amount of olefin remaining after the partial hydrogenation. Hydrogenation was accomplished using tosyl hydrazide. The degree of hydrogenation can be controlled by altering the reaction time or reaction stoichiometry and the by-products can be easily removed during workup by precipitation into ethanol. Several polymers have been prepared using this reduction scheme including two polymers which had 54% and 68% olefin remaining. Free standing films (approx. 12 {micro}m) were prepared from the 68% olefin material using draw-down technique and subsequently irradiated with a UV lamp (365 nm) for thirty minutes to induce crosslinking via thiol-ene reaction. After crosslinking, the olefin IR-absorption band disappeared and the Tg of the matrix material increased; both desirable properties for IR metamaterial applications. The polymer system has inherent photopatternable behavior primarily because of solubility differences between the pre-polymer and cross-linked matrix. Photopatterned structures using the 54% as well as the 68% olefin material were easily obtained. The synthesis, processing, and IR absorption data and the ramifications to dielectric metamaterials will be discussed.

Arrington, Christian Lew; Sinclair, Michael B.; Ginn, James Cleveland, III; Lee, Yun-Ju; Sanchez, Andrea E.; Clem, Paul Gilbert; Hines, Paul; Dirk, Shawn M.; Rasberry, Roger D.

2010-11-01

280

Five-coordinate nickel(II) complexes with carboxylate anions and derivatives of 1,5,9-triazacyclododec-1-ene: structural and 1H NMR spectroscopic studies.  

PubMed

The hydroxo complexes [Ni2(mcN3)2(mu-OH)2]2(PF6)2[mcN3 = 2,4,4-trimethyl-1,5,9-triazacyclododec-1-ene (Me3-mcN3) or 2,4,4,9-tetramethyl-1,5,9-triazacyclododec-1-ene (Me4-mcN3)] react with the corresponding carboxylic acid [HA = benzoic (Hbz), salicylic (Hsal) or acetylsalicylic (Hacsal) acid] to give five-coordinate nickel(II) complexes of the type [Ni(mcN3)(A)](PF6). The complexes have been studied by spectroscopic methods (IR, UV-Vis and 1H NMR). In acetone solution they exhibit isotropically shifted 1H NMR resonances. The full assignment of these resonances has been made using one- and two-dimensional 1H NMR techniques. The single-crystal structures of [Ni(Me4-mcN3)(bz)](PF6), [Ni(Me4-mcN3)(sal)](PF6) and[Ni(Me4-mcN3)(acsal)](PF6) have been established by X-ray diffraction. PMID:15605152

Santana, M Dolores; Lozano, A Abel; Garcia, Gabriel; Lopez, Gregorio; Perez, Jose

2005-01-01

281

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

282

Synthesis of novel 16-spiro steroids: spiro-7'-(aryl)tetrahydro-1H-pyrrolo[1,2-c][1,3]thiazolo-trans-androsterone hybrid heterocycles.  

PubMed

The 1,3-dipolar cycloaddition of azomethine ylide derived in situ from the reaction of acenaphthylene-1,2-dione and 1,3-thiazolane-4-carboxylic acid to various exocyclic dipolarophiles synthesized from trans-androsterone and trans-dehydroandrosterone afforded a library of novel spiro[5'.2?]acenaphthylene-1?-one-spiro[16.6']-(7'-aryl)-tetrahydro-1H-pyrrolo [1,2-c][1,3]thiazolo-trans-androsterone/dehydroandrosterone hybrid heterocycles respectively. These reactions proceeded stereo-specifically affording a single isomer of the 16-spiro steroids in excellent yields. PMID:23376110

Kanchithalaivan, Selvaraj; Kumar, Raju Ranjith; Perumal, Subbu

2013-04-01

283

Use of quantitative 1 H NMR chemical shift changes for ligand  

E-print Network

ARTICLE Use of quantitative 1 H NMR chemical shift changes for ligand docking into barnase Marina.V. 2008 Abstract 1 H NMR complexation-induced changes in chemical shift (CIS) of HN protons have been used Docking Á Guanine Abbreviations CIS Complexation-induced shift Ddexp Limiting chemical shift change

Williamson, Mike P.

284

Intestinal Transplantation With Alemtuzumab (Campath-1H) Induction for Adult Patients  

Microsoft Academic Search

BackgroundAlemtuzumab (Campath-1H [C1H]) is a humanized monoclonal antibody directed against the CD 52 antigen that is present on the surface of T cells, B cells, natural killer cells and monocytes. We studied its application in intestinal transplantation.

S. Nishida; D. M. Levi; J. I. Moon; J. R. Madariaga; T. Kato; G. Selvaggi; P. Tryphonopoulos; W. DeFaria; S. Santiago; J. Gaynor; D. Weppler; E. Martinez; P. Ruiz; A. G. Tzakis

2006-01-01

285

Hybrid inorganicorganic proton exchange membranes containing 1H-1,2,3-triazole moieties  

E-print Network

Hybrid inorganic­organic proton exchange membranes containing 1H-1,2,3-triazole moieties Shilpi Received in revised form 22 June 2010 Accepted 24 June 2010 Keywords: 1,2,3-Triazole Sol­gel Inorganic of 1H-1,2,3-triazole grafted alkoxy silanes, tetraethoxy silane (TEOS), polyethylene glycol (PEG

286

Proton Conducting Polymers Containing 1H-1,2,3-Triazole SURANGKHANA MARTWISET,1  

E-print Network

Proton Conducting Polymers Containing 1H-1,2,3-Triazole Moieties SURANGKHANA MARTWISET,1 OZGUR of 1H-1,2,3-triazole groups per repeat unit have been synthesized via conventional free radical triazole per repeat unit did not result in an increase in conductivity as there was an accompany- ing

287

A critical evaluation of heteronuclear TOCSY (HEHAHA) experiments for (1) H,(6) Li spin pairs.  

PubMed

Heteronuclear TOCSY (HEHAHA) experiments for (1) H,(6) Li spin pairs in organolithium compounds with adjacent strongly coupled (1) H,(1) H spin systems showed unexpected cross peak behaviour: for n-butyllithium (1) H,(6) Li cross peaks were completely missing, whereas for the dimer of (Z)-2-lithio-1-(o-lithiophenyl)ethane, a cross peak for remote protons was observed even at very short mixing times. It was assumed that strong magnetization transfer within the proton spin systems was responsible for these results, which prevented unambiguous chemical shift assignments. Selective experiments with the (6) Li,(1) H-HET-PLUSH-TACSY sequence then showed the expected (6) Li,(1) H cross peaks for the transfer via the directly coupled (1) H and (6) Li nuclei. For n-butyllithium transfer to H(C? ) via an unresolved heteronuclear coupling constant below 0.1?Hz is unambiguously observed. Cross peaks in the 2D (6) Li,(1) H-HET-PLUSH-TACSY spectra for the dimer of (Z)-2-lithio-1-(o-lithiophenyl)ethane are readily explained by the measured coupling network and the corresponding active mixing conditions. Copyright © 2014 John Wiley & Sons, Ltd. PMID:25169197

Bergander, Klaus; Hüls, Dietmar; Glaser, Steffen J; Günther, Harald; Luy, Burkhard

2014-12-01

288

Multicomponent analysis of encapsulated marine oil supplements using high-resolution 1 H and  

Microsoft Academic Search

Multicomponent high-resolution 1 H and 13 C NMR analysis has been employed for the purpose of detecting and quantifying a wide range of fatty acids (as triacylglycerols or otherwise) in encapsulated marine cod liver oil supple- ments. The 1 H NMR technique provided quantitative data regarding the docosahexaenoic acid content of these prod- ucts, which serves as a valuable index

Navaede Siddiqui; Julia Sim; Christopher J. L. Silwood; Harold Toms; Richard A. Iles; Martin Grootveld

289

Synthesis of 3-alkyl(Aryl)-4-alkylidenamino-4,5-dihydro-1H-1,2,4-triazol-5-ones and 3-alkyl-4-alkylamino-4,5-dihydro-1H-1,2,4-triazol-5-ones as antitumor agents  

Microsoft Academic Search

A series of 3-alkyl-4-phenylethylidenamino- (8) and 3-alkyl-4-(3-phenylallylidenamino)-4,5-dihydro-1H-1,2,4-triazol-5-ones (9) was synthesized from the reaction of the corresponding 3-alkyl(aryl)-4-amino-4,5-dihydro-1H-1,2,4-triazol-5-ones (1), with phenylacetaldehyde and cinnamaldehyde. 3-Alkyl-4-(2-phenylethylamino)- (10) and 3-alkyl-4-(3-phenylpropylamino)-4,5-dihydro-1H-1,2,4-triazol-5-ones (11) were obtained from the selective reduction of compounds (8) and (9) with NaBH4. The in vitro antitumor activity of the novel compounds was screened and the highest inhibition of tree tumor cell lines

Neslihan Demirba?; Ahmet Demirba?

2002-01-01

290

Selective hydrogenation of o-chloronitrobenzene over anatase-ferric oxides supported Ir nanocomposite catalyst.  

PubMed

The catalytic performance of Ir/TiO2-FeOx, an Ir/TiO2 catalyst modified with FeOx, was investigated for the hydrogenation of o-chloronitrobenzene, FeOx was found to promote both the activity and selectivity significantly. The initial reaction rate of Ir/TiO2-FeOx(10) nanocomposite catalyst was four times as high as that of Ir/TiO2 catalyst. Especially, the accumulation of intermediates was prohibited and finally 100% selectivity to o-chloroaniline was obtained at 100% conversion. Herein, we mainly discussed the promoting effect of FeOx with using the results of powder X-ray diffraction, transmission electron microscopy, element analysis mapping, hydrogen-temperature programmed reduction, hydrogen-temperature programmed desorption, diffuse reflectance infrared fourier transform spectra and X-ray photoelectron spectroscopy analysis. The FeOx was highly dispersed and a portion of FeO species existed in the Ir/TiO2-FeOx nanocomposite catalyst. Moreover, the FeOx was certified to have a strong interaction with Ir species, which should contribute to the excellent performance of the Ir/TiO2-FeOx nanocomposite catalyst. PMID:25086395

Lin, Weiwei; Zhao, Jia; Cheng, Haiyang; Li, Xiaoru; Li, Xiaonian; Zhao, Fengyu

2014-10-15

291

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

292

Transcriptional regulation of ?1H T-type calcium channel under hypoxia.  

PubMed

The low-voltage-activated T-type Ca(2+) channels play an important role in mediating the cellular responses to altered oxygen tension. Among three T-type channel isoforms, ?1G, ?1H, and ?1I, only ?1H was found to be upregulated under hypoxia. However, mechanisms underlying such hypoxia-dependent isoform-specific gene regulation remain incompletely understood. We, therefore, studied the hypoxia-dependent transcriptional regulation of ?1G and ?1H gene promoters with the aim to identify the functional hypoxia-response elements (HREs). In rat pulmonary artery smooth muscle cells (PASMCs) and pheochromocytoma (PC12) cells after hypoxia (3% O2) exposure, we observed a prominent increase in ?1H mRNA at 12 h along with a significant rise in ?1H-mediated T-type current at 24 and 48 h. We then cloned two promoter fragments from the 5'-flanking regions of rat ?1G and ?1H gene, 2,000 and 3,076 bp, respectively, and inserted these fragments into a luciferase reporter vector. Transient transfection of PASMCs and PC12 cells with these recombinant constructs and subsequent luciferase assay revealed a significant increase in luciferase activity from the reporter containing the ?1H, but not ?1G, promoter fragment under hypoxia. Using serial deletion and point mutation analysis strategies, we identified a functional HRE at site -1,173cacgc-1,169 within the ?1H promoter region. Furthermore, an electrophoretic mobility shift assay using this site as a DNA probe demonstrated an increased binding activity to nuclear protein extracts from the cells after hypoxia exposure. Taken together, these findings indicate that hypoxia-induced ?1H upregulation involves binding of hypoxia-inducible factor to an HRE within the ?1H promoter region. PMID:25099734

Sellak, Hassan; Zhou, Chun; Liu, Bainan; Chen, Hairu; Lincoln, Thomas M; Wu, Songwei

2014-10-01

293

Synthesis and antiprotozoal activity of novel 2-{[2-(1H-imidazol-1-yl)ethyl]sulfanyl}-1H-benzimidazole derivatives.  

PubMed

A series of 19 new 2-{[2-(1H-imidazol-1-yl)ethyl]sulfanyl}-1H-benzimidazole derivatives was synthesized starting from the properly substituted 1,2-phenylendiamine. These compounds have hydrogen or methyl at position 1; while hydrogen, chlorine, ethoxy or methoxycarbonyl group is at position 5 and/or 6. The novel compounds were tested against protozoa Trichomonas vaginalis, Giardia intestinalis and Entamoeba histolytica. Experimental evaluations revealed strong activity for all tested compounds, having IC50 values in the nanomolar range, which were even better than metronidazole, the drug of choice for these parasites. PMID:23731944

Pérez-Villanueva, Jaime; Hernández-Campos, Alicia; Yépez-Mulia, Lilián; Méndez-Cuesta, Carlos; Méndez-Lucio, Oscar; Hernández-Luis, Francisco; Castillo, Rafael

2013-07-15

294

Microbial biodegradation of a novel fluorotelomer alcohol, 1 H ,1 H ,2 H ,2 H ,8 H ,8 H -perfluorododecanol, yields short fluorinated acids  

Microsoft Academic Search

The accumulation of perfluorooctanoic acid (PFOA) has been detected in wildlife, soil, and water. Further, 8:2 fluorotelomer\\u000a alcohol (8:2 FTOH) is used for the industrial synthesis of other fluorotelomer compounds, surfactants, and polymeric materials;\\u000a however, it was recently found to be a potential source of PFOA contamination in the environment. 1H,1H,2H,2H,8H,8H-perfluorododecanol (degradable telomer fluoroalcohol (DTFA)), which is a newly developed

Atsushi Arakaki; Yuko Ishii; Takahito Tokuhisa; Seiichiro Murata; Katsuyuki Sato; Takehiro Sonoi; Haruyoshi Tatsu; Tadashi Matsunaga

2010-01-01

295

Paprastosios ir keturbriaun?s jonažoli? azoto ir sunki?j? metal? koncentracijos ypatumai.  

E-print Network

??Magistro darbe tiriama paprastosios ir keturbriaun?s jonažoli? azoto ir sunki?j? metal? koncentracijos ypatumai. Master degree work cover the studies of nitrogen and heavy metals concentration‘s… (more)

Ramonait?,; Kristina

2009-01-01

296

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

297

Synthesis and fungicidal activity of novel 3-(substituted/unsubstituted phenylselenonyl)-1-ribosyl/deoxyribosyl-1H-1,2,4-triazole.  

PubMed

Reaction of potassium 1H-1,2,4-triazole-3-selenolate (I) with acetylated ribose/deoxyribose (IIa,b) in the presence of montmorillonite K 10 as a solid adsorbent furnished potassium 1-acetylated ribosyl/deoxyribosyl-1H-1,2,4-triazole-3-selenolate (IIIa,b) with excellent yield under microwave irradiation in solvent-free conditions. This eliminates a series of complex isolation procedures and often minimizes the use of a large amount of expensive, toxic, and hazardous solvents after each step. This procedure reduces reaction time and cost and enhances yield. Reaction of compound (IIIa,b) with substituted/unsubstituted aryl diazonium chloride (IVa-e) at 0-5 °C gave pure 3-(substituted/unsubstituted phenyl selanyl)-1-acetylribosyl/deoxyribosyl-1H-1,2,4-triazole (Va-j). Oxidation of compound (Va-j) with oxone followed by alkaline hydrolysis furnished quantitatively and analytically pure 3-(substituted/unsubstituted phenylselenonyl)-1-ribosyl/deoxyribosyl-1H-1,2,4-triazole (VIIa-j). Compounds VIa-j and VIIa-j were evaluated in vitro for their fungitoxicities against Fusarium oxysporum and Penicillium citrinum. All the compounds were found to be antifungal active. Some of the compounds displayed activities comparable with that of the commercial fungicide Dithane M-45 and griseofulvin. Structure-activity relationships for the screened compounds were discussed. The fact that both of these fungi have developed resistance to several fungicide groups made them optimal candidates as target organisms for ongoing research about the potential application of 1,2,4-triazole and analogue compounds as reduced-risk fungicides. PMID:22563913

Singh, Pravin K

2012-06-13

298

0 (IR + ) = span f e ' 0k : S k e  

E-print Network

and 0 e V B 0 (IR + ) = span f e ' 0k : S Ÿ k Ÿ e L \\Gamma 1g := span 0 e \\Phi 0 : (7­spline case (see Proposition 9.1 and also [15]). As before, we set 0 V j (IR + ) := T j ( 0 V 0 (IR + )) and 0 e V j (IR + ) := f T j ( 0 e V 0 (IR + )): Let us define 0 P 0 : L p (IR + ) \\Gamma! 0 V 0 (IR

Tabacco, Anita

299

The IR Luminosity Functions of Rich Clusters  

E-print Network

We present MIPS observations of the cluster A3266. About 100 spectroscopic cluster members have been detected at 24 micron. The IR luminosity function in A3266 is very similar to that in the Coma cluster down to the detection limit L_IR~10^43 ergs/s, suggesting a universal form of the bright end IR LF for local rich clusters with M~10^15 M_sun. The shape of the bright end of the A3266-Coma composite IR LF is not significantly different from that of nearby field galaxies, but the fraction of IR-bright galaxies (SFR > 0.2M_sun/yr) in both clusters increases with cluster-centric radius. The decrease of the blue galaxy fraction toward the high density cores only accounts for part of the trend; the fraction of red galaxies with moderate SFRs (0.2 IR bright galaxies, nearby rich clusters are distinguished from the field by a lower star-forming galaxy fraction, but not by a change in L*_IR. The composite IR LF of Coma and A3266 shows strong evolution when compared with the composite IR LF of two z~0.8 clusters, MS 1054 and RX J0152, with L*_IR \\propto (1+z)^{3.2+/-0.7},Phi*_IR \\propto (1+z)^{1.7+/-1.0}. This L*_IR evolution is indistinguishable from that in the field, and the Phi*_IR evolution is stronger, but still consistent with that in the field. The similarity of the evolution of bright-end IR LF in very different cluster and field environments suggests either this evolution is driven by the mechanism that works in both environments, or clusters continually replenish their star-forming galaxies from the field, yielding an evolution in the IR LF that is similar to the field. The mass-normalized integrated star formation rates (SFRs) of clusters within 0.5R_200 also evolve strongly with redshift, as (1+z)^5.3.

Lei Bai; George H. Rieke; Marcia J. Rieke; Daniel Christlein; Ann I. Zabludoff

2008-12-02

300

Special Reactions  

NSDL National Science Digital Library

The basics of chemical reactions were covered in the first chemistry book, including how to write and balance chemical equations that represent those reactions. There is also a quick review of chemical reactions in Chapter 1 of this book. We're going to d

Robertson, William C.

2010-03-01

301

Enzyme Reactions  

NSDL National Science Digital Library

This video shows an enzyme reaction lab. The teacher demonstrates how the enzyme, catalase, reacts with hydrogen peroxide (a substrate found in cells). The teacher first demonstrates a normal enzyme reaction. He or she then goes on to show how manipulating temperature and pH will affect the reaction of an enzyme.

School, Minerva D.

2011-10-03

302

Chemical Reactions  

NSDL National Science Digital Library

We don't often stop to think about it, but underlying many of our everyday activities are chemical reactions. From the cooking of an egg to the growth of a child, chemical reactions make things happen. Although many of the reactions that support our lives

National Science Teachers Association (NSTA)

2009-05-01

303

Reversible Reactions  

NSDL National Science Digital Library

Watch a reaction proceed over time. How does total energy affect a reaction rate? Vary temperature, barrier height, and potential energies. Record concentrations and time in order to extract rate coefficients. Do temperature dependent studies to extract Arrhenius parameters. This simulation is best used with teacher guidance because it presents an analogy of chemical reactions.

Simulations, Phet I.; Barbera, Jack; Koch, Linda; Lemaster, Ron; Adams, Wendy

2005-09-01

304

Nuclear Reactions  

Microsoft Academic Search

Nuclear reactions generate energy in nuclear reactors, in stars, and are responsible for the existence of all elements heavier than hydrogen in the universe. Nuclear reactions denote reactions between nuclei, and between nuclei and other fundamental particles, such as electrons and photons. A short description of the conservation laws and the definition of basic physical quantities is presented, followed by

C. A. Bertulani

2009-01-01

305

Improved background suppression in 1H MAS NMR using composite pulses  

NASA Astrophysics Data System (ADS)

A well known feature of 1H MAS NMR spectroscopy, particularly of solids where the concentration of 1H nuclei is low, is the presence in the spectrum of a significant broad "background" signal arising from 1H nuclei that are outside the MAS rotor and radiofrequency coil, probably located on the surfaces of the static components of the probehead. A popular method of suppressing this unwanted signal is the "depth pulse" method, consisting of a 90° pulse followed by one or two 180° pulses that are phase cycled according to the "Exorcycle" scheme, which removes signal associated with imperfect 180° pulses. Consequently, only spins in the centre of the radiofrequency coil contribute to the 1H MAS spectrum, while those experiencing a low B1 field outside the coil are suppressed. Although very effective at removing background signal from the spectrum, one drawback with this approach is that significant loss of the desired signal from the sample also occurs. Here we investigate the 1H background suppression problem and, in particular, the use of novel antisymmetric passband composite pulses to replace the simple pulses in a depth pulse experiment. We show that it is possible to improve the intensity of the 1H signals of interest while still maintaining effective background suppression. We expect that these results will be relevant to 1H MAS NMR studies of, for example, nominally perdeuterated biological samples or nominally anhydrous inorganic materials.

Odedra, Smita; Wimperis, Stephen

2012-08-01

306

1-Ethyl-2-phenyl-3-[2-(tri­methyl­sil­yl)ethyn­yl]-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. PMID:23795091

Baglai, Iaroslav; Maraval, Valérie; Duhayon, Carine; Chauvin, Remi

2013-01-01

307

Syntheses, structures and properties of novel lanthanide complexes with 5-(1 H-imidazol-4-yl)methylaminoisophthalic acid  

NASA Astrophysics Data System (ADS)

Reactions of ligand 5-(1 H-imidazol-4-yl)methylaminoisophthalic acid (H 3L) with varied lanthanide metal salts led to the formation of five scalelike 2D layered complexes {[Ln(H 2L)(HL)(H 2O) 2]·H 2O} n [Ln(III) = Pr(III) ( 1), Nd(III) ( 2), Sm(III) ( 3), Gd(III) ( 4), Tb(III) ( 5)]. The single crystal X-ray diffraction analyses revealed that five complexes crystallized in the same monoclinic space group C2/ c are isomorphous and isostructural, and the 2D networks are further connected by hydrogen bonds and ?-? interactions resulting in formation of 3D structures. Investigations on the visible luminescent property of the complexes demonstrate that compounds 3 and 5 show characteristic emissions of Sm(III) and Tb(III) in the solid state at room temperature, respectively.

Xu, Jing; Liu, Qing; Okamura, Taka-aki; Chen, Man-Sheng; Sun, Wei-Yin; Ueyama, Norikazu

2009-11-01

308

Synthesis and characterization of some new Schiff base complexes of group 13 elements, ab initio studies, cytotoxicity and reaction with hydrogen peroxide  

NASA Astrophysics Data System (ADS)

A novel tetradentate Schiff base, naphthabza-H2 = N,N'-bis(naphthylidene)-2-aminobenzylamine, and a series of aluminum(III), gallium(III), and indium(III) complexes with general formula, MLNO3, were synthesized and characterized by elemental analysis, 1H NMR, FT-IR, UV-Vis spectroscopy and thermogravimetric method. The product of the reaction of complexes with hydrogen peroxide was characterized by similar techniques. According to the ab initio calculations aluminum and gallium complexes have five-coordinated structures and indium complex is a six-coordinated one. Also, the growth inhibitory effects of the complexes toward K562 cancer cell line were measured and the results for these complexes are as follows: Al > Ga > In.

Asadi, Mozaffar; Savaripoor, Nooshin; Asadi, Zahra; Ghatee, Mohammad Hadi; Moosavi, Fatemeh; Yousefi, Reza; Jamshidi, Mehrnaz

2013-01-01

309

Hydrogen bonding interactions of ?-phenylcinnamic acid isomers in the liquid phase studied by IR and NMR spectroscopies and computational methods  

Microsoft Academic Search

Intra- and intermolecular hydrogen bonding interactions of ?-phenylcinnamic acid isomers were studied in the solution phase by infrared (IR) and proton nuclear magnetic resonance (1H NMR) spectroscopies and the AM1 semi-empirical method. The solvents were CDCl3 or dimethyl sulfoxide (DMSO), the concentration of the acid isomers were varied. Spectroscopic measurements revealed that (i) intermolecular hydrogen bonds are typical for both

I. Pálinkó; B. Török; M. Rózsa-Tarjányi; J. T. Kiss; Gy. Tasi

1995-01-01

310

Synthesis and anthelminthic activity of alkyl-(5-acyl-1-H-benzimidazol-2-yl) carbamates.  

PubMed

A series of alkyl-(5-acyl-1-H-benzimidazol-2-yl)-carbamates were prepared and screened for anthelminthic activity. Some of them were found to be fully active at low, atoxic oral dose levels against gastro-intestinal nematodes. The activity against Symphacia muria and Strongyloides ratta is indicated. From these studies methyl (5-benzoyl-1-H-benzimidazol-2-yl) carbamate (mebendazole) and methyl [5-(4-flourobenzoyl)-1-H-benzimiazol-2 yl]carbamate flubendazole) were selected for detailed investigation. PMID:581933

Raeymaekers, A H; Van Gelder, J L; Roevens, L F; Janssen, P A

1978-01-01

311

A belief network model for IR  

Microsoft Academic Search

We introduce a belief network model for IR which is derived from probabilistic considerations over a clearly defined sam- ple space. This model subsumes the classical models in IR and generalizes the inference network model of Turtle and Croft. Further, we show how to extend the model with infor- mation from other queries (which we call contexts) to yield improved

Berthier A. Ribeiro-Neto; Richard R. Muntz

1996-01-01

312

On $?$-Deformation and UV/IR Mixing  

E-print Network

We examine the UV/IR mixing property on a $\\kappa$-deformed Euclidean space for a real scalar $\\phi^4$ theory. All contributions to the tadpole diagram are explicitly calculated. UV/IR mixing is present, though in a different dressing than in the case of the canonical deformation.

Harald Grosse; Michael Wohlgenannt

2005-07-04

313

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

314

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

315

IR imaging using uncooled microcantilever detectors.  

PubMed

Uncooled bimaterial microcantilever detectors were fabricated and used to obtain infrared (IR) images of objects at temperatures ranging from room temperature to a few hundred degrees C. Images were obtained using both single 50 micro m x 50 micro m microcantilever IR detectors and arrays of microcantilever detectors. Thermal radiation from the target object was imaged onto the detector and the resulting temperature change caused microcantilever bending due to the bimaterial effect. This micromechanical bending was measured using two different non-contact optical readout techniques and IR images were obtained. A smaller size (20 micro m x 20 micro m) microcantilever IR detector was also used to capture IR images of near room temperature objects. PMID:12801701

Senesac, L R; Corbeil, J L; Rajic, S; Lavrik, N V; Datskos, P G

2003-01-01

316

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 Salg?n; Alpaslan, Yelda Bingöl; Kelekçi, Nesrin Gökhan; I??k, ?amil; Ekizo?lu, Melike

2013-05-01

317

Near-Infrared Polarimetric Study of Monoceros R2 IRS  

NASA Astrophysics Data System (ADS)

We present H- and Ks-band imaging polarimetry for the star-forming region Mon R2 IRS, and spectropolarimetry from 1.2 to 4.2 ?m for the infrared sources IRS 2 and IRS 3. The nebular complex in Mon R2 IRS is revealed to be composed of four domains dominated by the infrared sources IRS 1, IRS 2, IRS 3, and IRS 6. IRS 2 is the predominant illuminating source in the region and dominates the emission of the IR ring and most of the western part of the nebulosity. IRS 1 is responsible for the enhanced unpolarized intensity in the southeast part of the IR ring and inside the IR ring. IRS 3 illuminates the bright eastern nebula, and together with IRS 2 illuminates the eastern region inside the IR ring. IRS 6 illuminates a small nebula to the south of the IR ring. An arc structure of polarized intensity is observed abutting the northwest IR ring, consistent with the outflow cavity structure inferred from millimeter-wave observations. IRS 3 is associated with a disklike condensation oriented southeast-northwest, perpendicular to the elongated eastern nebula. The magnetic field in the core region exhibits an hourglass structure oriented north-south.

Yao, Yongqiang; Hirata, Naohisa; Ishii, Miki; Nagata, Tetsuya; Ogawa, Yasunobu; Sato, Shuji; Watanabe, Makoto; Yamashita, Takuya

1997-11-01

318

Reactions of Pd(II) and Pt(II) Complexes With Tetraethylthiouram Disulfide  

PubMed Central

The reactions of tetraethylthiouram disulfide (DTS), an inhibitor of the nephrotoxicity of Pt(II) drugs, an efficient agent in the treatment of chronic alcoholism, in the treatment of HIV infections, AIDS and heavy metal toxicity, and a fungicide and herbicide, with K2[PtCl4], in ratio 1:1 and 1:2, gave the compounds [PtCl2DTS] and [Pt(S2CNEt2)2] respectively. The reaction of the complexes K2[PdCl4], Pd(AcO)2 and [PdCl2(PhCN)2], where PhCN = Benzonitrile, with tetraethylthiouram disulfide in ratio 1:1 or 1:2, yielded orange crystals identified as [Pd(S2CNEt2)2]. The crystals were suitable for study by X-ray diffraction. The -S-S- bridge in the tetraethylthiouram disulfude molecule was broken and the two molecules of the thiocarbamate derivative were bound to the Pd(II) by the equivalents sulfur atoms. All the compounds were characterized by IR, 1H and 13C NMR spectroscopies. PMID:18475812

Cervantes, G.; Molins, E.; Miravitlles, C.

1997-01-01

319

Synthesis of branched cores by poly-O-alkylation reaction under phase transfer conditions. A systematic study  

NASA Astrophysics Data System (ADS)

In the present paper is described a systematic study of poly-O-alkylation reactions of pentaerythritol (PE) and 1,1,1-tris(hydroxymethyl)ethane (TME) by 1,4 Michael addition, under phase transfer catalysis (PTC), considering the effect of: (1) the organophilicity of PTC (three different catalysts were tested), (2) PTC concentration (from catalytic to equimolar conditions), and (3) the regime of addition of reactants coexisting in the aqueous phase of the heterogeneous reaction system. The less organophilic transfer agent showed the best performance on these reactions. In our case, benzyltriethylammonium chloride (TEBAC) gathers the best features. The presence of NaOH as base, promotes the interfacial mechanism and not the bulk one. Out of the optimal range of concentration of NaOH (35-40%), competition between nucleophiles can occur, due to the saturation of the medium. Regarding the regime of addition of reactants, the scenario where NaOH and TEBAC are less time in contact, favors the formation of the desired products. Finally, the deprotection of tert-butyl groups of the poly-O-alkylated compounds is described, to get branched cores with terminal carboxylic acid groups in good yields (90-94%). Spectroscopic properties, such as IR, 1H and 13C NMR, of the synthesized compounds are also described.

Landeros, José M.; Silvestre, Hugo A.; Guadarrama, Patricia

2013-04-01

320

The effect of paramagnetic manganese cations on 1 H MR spectroscopy of the brain  

E-print Network

The effect of paramagnetic manganese cations on 1 H MR spectroscopy of the brain K. S. Madsen1 properties of divalent manganese cations (Mn2+ ) and their in vivo resemblance to calcium cations (Ca2+ ) has

321

Multi-Higgs doublet models with local U(1)H gauge symmetry and neutrino physics therein  

NASA Astrophysics Data System (ADS)

Multi-Higgs doublet models appear in many interesting extensions of the standard model (SM). But they suffer from Higgs-mediated flavor changing neutral current (FCNC) problem which is very generic. In this talk, I describe that this problem can be resolved or mitigated if we introduce local U(1)H Higgs flavor gauge symmetry. As examples, I describe chiral U(1)H models where the right-handed up-type quarks also carry U(1)H charges and discuss the top forward-backward asymmetry (FBA) and B ? D(*)?? puzzle. Next I describe the two-Higgs doublet models where the usual Z2 symmetry is implemented to U(1)H and show how the Type-I and Type-II models are extended. One possible extension of Type-II has the same fermion contents with the leptophobic E6Z' model by Rosner, and I discuss the neutrino sector in this model briefly.

Ko, P.; Omura, Yuji; Yu, Chaehyun

2014-06-01

322

Low energy theorem and polarization effects in sup 2 H(. gamma. , n ) sup 1 H  

SciTech Connect

Polarization effects in {sup 2}H({gamma},{ital n}){sup 1}H are considered in the low photon energy domain. We discuss linear photon polarization, one-nucleon polarization, and vector target asymmetry.

Alvarado, J.J.; Lucio M, J.L. (Institut fur Kernphysik, J. Gutenberg Universitat, D-6500 Mainz, Federal Republic of Germany (DE) Departamento de Fisica, Centro de Investigacion y de Estudios Avanzados Instituto Politecnico Nacional, 07000 Mexico, Distrito Federal, Mexico); Pestieau, J. (Institut de Physique Theorique, Universite Catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium)

1989-08-01

323

32 CFR 1630.15 - Class 1-H: Registrant not subject to processing for induction.  

Code of Federal Regulations, 2013 CFR

...Registrant not subject to processing for induction. 1630.15 Section 1630.15...Registrant not subject to processing for induction. In Class 1-H shall be placed...currently subject to processing for...

2013-07-01

324

32 CFR 1630.15 - Class 1-H: Registrant not subject to processing for induction.  

Code of Federal Regulations, 2012 CFR

...Registrant not subject to processing for induction. 1630.15 Section 1630.15...Registrant not subject to processing for induction. In Class 1-H shall be placed...currently subject to processing for...

2012-07-01

325

32 CFR 1630.15 - Class 1-H: Registrant not subject to processing for induction.  

Code of Federal Regulations, 2010 CFR

...Registrant not subject to processing for induction. 1630.15 Section 1630.15...Registrant not subject to processing for induction. In Class 1-H shall be placed...currently subject to processing for...

2010-07-01

326

32 CFR 1630.15 - Class 1-H: Registrant not subject to processing for induction.  

...Registrant not subject to processing for induction. 1630.15 Section 1630.15...Registrant not subject to processing for induction. In Class 1-H shall be placed...currently subject to processing for...

2014-07-01

327

32 CFR 1630.15 - Class 1-H: Registrant not subject to processing for induction.  

Code of Federal Regulations, 2011 CFR

...Registrant not subject to processing for induction. 1630.15 Section 1630.15...Registrant not subject to processing for induction. In Class 1-H shall be placed...currently subject to processing for...

2011-07-01

328

Spitzer IRS Analysis of Neptune  

NASA Astrophysics Data System (ADS)

Recent (2005) Spitzer Infrared Spectrometer (IRS) data of Neptune between 5 and 20 um contain a wealth of information about the chemical composition and temperature structure of its cold atmospheres. Emission features in its spectrum arise from many hydrocarbons, including ethane, acetylene and methane, and they appear to be superimposed on top of a collision-induced H2 continuum. As the derivation of all other parameters depends on the assumed temperature profile, special efforts were taken to ensure that the stratospheric profile between 1 bar and 0.3 mbar matched the H2 continuum and the H2 S(1) quadrupole feature at 17 um. Additionally we matched the methane v4 feature at 7.7 um in order to constrain the stratospheric temperature profile above the 0.3-mbar level as well as the methane stratospheric volume mixing ratios (VMRs). After the determination of the temperature profile and methane VMRs, the VMRs for several species were then determined through fitting their corresponding features in the spectrum, initially by scaling existing photochemical models (see Mahmud et al., this conference). These species include methylacetylene, diacetylene, benzene, acetylene, ethane, methyl radical, ethylene and carbon dioxide which are all derived from methane photochemistry. I would like to acknowledge the NASA USRP program for supporting this work.

Line, Michael R.; Orton, G. S.; Fletcher, L. N.; Mahmud, A.; Moses, J. I.; Mainzer, A. K.; Yung, Y. L.

2008-09-01

329

(Phenoxyimidazolyl-salicylaldimine)iron complexes: synthesis, properties and iron catalysed ethylene reactions.  

PubMed

The reaction of 2-{[2-(1H-imidazol-4-yl)-ethylimino]-methyl}-phenol (L1), 2,4-di-tert-butyl-6-{[2-(1H-imidazol-4-yl)-ethylimino]-methyl}-phenol (L2) or 4-tert-butyl-2-{[2-(1H-imidazol-4-yl)-ethylimino]-methyl}-phenol (L3) with iron(ii) precursors produced either iron(ii) or iron(iii) complexes, depending on the nature of the anions in the iron(ii) precursor and the ligand. When the anion is chloride and the ligand L1, the product is [(L1)2Fe][FeCl4] (1), but when the anion is triflate (OTf(-)) and the ligand is L2, the product is [(L2)2Fe][OTf]2 (2). With iron(ii) halides and tert-butyl groups on the phenoxy ligands L2 and L3, the iron(iii) complexes [(L2)FeX2] {where X = Cl (3), Br (4) and I = (5)} and [(L3)FeCl2] (6) were formed. Complexes 1-6 were characterised by a combination of elemental analyses, IR spectroscopy and mass spectrometry; and in selected cases (3 and 4) by single crystal X-ray crystallography. The crystal structures of 3 and 4 indicated that the iron(ii) precursors oxidised to iron(iii) in forming complexes 3-6; an observation that was corroborated by the magnetic properties and the (57)Fe Mössbauer spectra of 3 and 4. The iron(iii) complexes 3-6 were used as pre-catalysts for the oligomerisation and polymerisation of ethylene. Products of these ethylene reactions depended on the solvent used. In toluene ethylene oligomerised mainly to 1-butene and was followed by the 1-butene alkylating the solvent to form butyl-toluenes via a Friedel-Crafts alkylation reaction. In chlorobenzene, ethylene oligomerised mainly to a mixture of C4-C12 alkenes. Interestingly small amounts of butyl-chlorobenzenes and hexyl-chlorobenzenes were also formed via a Friedel-Crafts alkylation with butenes and hexenes from the oligomerisation of ethylene. PMID:25111396

Yankey, Margaret; Obuah, Collins; Guzei, Ilia A; Osei-Twum, Emmanuel; Hearne, Giovanni; Darkwa, James

2014-10-01

330

Medium and Long-Distance 1H– 13C Heteronuclear Correlation NMR in Solids  

Microsoft Academic Search

A simple method for obtaining 1H–13C HETCOR solid-state NMR spectra reflecting only medium- and long-range 1H–13C correlation peaks is presented. By dephasing the magnetization of protons directly bonded to a 13C nucleus, the short-range correlation peaks, which contain limited structural information, can be cleanly suppressed without reducing the long-range cross peaks significantly. The resulting reduction of resonance overlap simplifies spectral

X. L. Yao; K. Schmidt-Rohr; M. Hong

2001-01-01

331

5-Substituted-1 H-tetrazoles as carboxylic acid isosteres: medicinal chemistry and synthetic methods  

Microsoft Academic Search

5-Substituted-1H-tetrazoles (RCN4H) are often used as metabolism-resistant isosteric replacements for carboxylic acids (RCO2H) in SAR-driven medicinal chemistry analogue syntheses. This review provides a brief summary of the medicinal chemistry of tetrazolic acids and highlights some examples of tetrazole-containing drug substances in the current literature. A survey of representative literature procedures for the preparation of 5-substituted-1H-tetrazoles, focusing on preparations from aryl

R. Jason Herr

2002-01-01

332

The molecular and crystal structure of (+/-)-1-methyl-7-oxa-norborn-5-ene-2exo,3exo-dicarboxylic acid-anhydride and its enantiodifferentiation in 1H NMR spectroscopy.  

PubMed

The Diels-Alder reaction between 2-methylfuran and maleic anhydride leads to the formation of known racemic title adduct 3. The structure of this compound was confirmed by X-ray crystallography. An efficient enantiodifferentiation of 3 in 1H NMR spectroscopy was observed upon treatment with Eu(hfc)3. PMID:11958342

Maurin, J K; Czarnocki, Z; Wojtasiewicz, K; Matuszewka, I; Zió?kowski, M

2001-01-01

333

New Cu(TiIrNx) Alloy Films for Solder Bump Flip-Chip Application  

NASA Astrophysics Data System (ADS)

A new copper alloy that shows fine thermal stability and adhesion to the substrate is developed in this study by cosputtering Cu, Ti, and Ir on a barrierless Si substrate within an Ar/N2 gas atmosphere to form a Cu(TiIrNx) film. To reduce manufacture cost, we can replace both the wetting and diffusion layers underneath flip-chip solder joints in conventional under bump metallurgy with this thermally stable film, which exhibits weak, if any, interactions between the film and the substrate after annealing at 700 °C for 1 h. The alloy film's dissolution rate is lower than that of pure Cu by at least one order of magnitude, with a fine solderability similar to that of pure Cu. The film developed in this study seems to be a good candidate material for barrierless Si metallization and/or flip-chip solder bump application, with a low consumption rate comparable to that of Ni.

Lin, Chon-Hsin

2013-11-01

334

Influence of the metal (Al, Cr, and Co) and substituents of the porphyrin in controlling reactions involved in copolymerization of propylene oxide and carbon dioxide by porphyrin metal(III) complexes. 3. Cobalt chemistry.  

PubMed

A series of cobalt(III) complexes LCoX, where L = 5,10,15,20-tetraphenylporphyrin (TPP), 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin (TFPP), and 2,3,7,8,12,13,17,18-octaethylporphyirn (OEP) and X = Cl or acetate, has been investigated for homopolymerization of propylene oxide (PO) and copolymerization of PO and CO2 to yield polypropylene oxide (PPO) and polypropylene carbonate (PPC) or propylene carbonate (PC), respectively. These reactions were carried out both with and without the presence of a cocatalyst, namely, 4-dimethylaminopyridine (DMAP) or PPN(+)Cl(-) (bis(triphenylphosphine)iminium chloride). The PO/CO2 copolymerization process is notably faster than PO homopolymerization. With ionic PPN(+)Cl(-) cocatalyst the TPPCoOAc catalyst system grows two chains per Co center and the presence of excess [Cl(-)] facilitates formation of PC by two different backbiting mechanisms during copolymerization. Formation of PPC is dependent on both [Cl(-)] and the CO2 pressure employed (1-50 bar). TPPCoCl and PO react to form TPPCo(II) and ClCH2CH(Me)OH, while with DMAP, TPPCoCl yields TPPCo(DMAP)2(+)Cl(-). The reactions and their polymers and other products have been monitored by various methods including react-IR, FT-IR, GPC, ESI, MALDI TOF, EXAFS, and NMR ((1)H, (13)C{(1)H}) spectroscopy. Notable differences are seen in these reactions with previous studies of (porphyrin)M(III) complexes (M = Al, Cr) and of the (salen)M(III) complexes where M = Cr, Co. PMID:23556475

Chatterjee, Chandrani; Chisholm, Malcolm H; El-Khaldy, Adnan; McIntosh, Ruaraidh D; Miller, Jeffrey T; Wu, Tianpin

2013-04-15

335

Finite-pulse radio frequency driven recoupling with phase cycling for 2D (1)H/(1)H correlation at ultrafast MAS frequencies.  

PubMed

The first-order recoupling sequence radio frequency driven dipolar recoupling (RFDR) is commonly used in single-quantum/single-quantum homonuclear correlation 2D experiments under magic angle spinning (MAS) to determine homonuclear proximities. From previously reported analysis of the use of XY-based super-cycling schemes to enhance the efficiency of the finite-pulse-RFDR (fp-RFDR) pulse sequence, XY8(1)4 phase cycling was found to provide the optimum performance for 2D correlation experiments on low-? nuclei. In this study, we analyze the efficiency of different phase cycling schemes for proton-based fp-RFDR experiments. We demonstrate the advantages of using a short phase cycle, XY4, and its super-cycle XY4(1)4 that only recouples the zero-quantum homonuclear dipolar coupling, for the fp-RFDR sequence in 2D (1)H/(1)H correlation experiments at ultrafast MAS frequencies. The dipolar recoupling efficiencies of XY4, XY4(1)4 and XY8(1)4 phase cycling schemes are compared based on results obtained from 2D (1)H/(1)H correlation experiments, utilizing the fp-RFDR pulse sequence, on powder samples of U-(13)C,(15)N-l-alanine, N-acetyl-(15)N-l-valyl-(15)N-l-leucine, and glycine. Experimental results and spin dynamics simulations show that XY4(1)4 performs the best when a high RF power is used for the 180° pulse, whereas XY4 renders the best performance when a low RF power is used. The effects of RF field inhomogeneity and chemical shift offsets are also examined. Overall, our results suggest that a combination of fp-RFDR-XY4(1)4 employed in the recycle delay with a large RF-field to decrease the recycle delay, and fp-RFDR-XY4 in the mixing period with a moderate RF-field, is a robust and efficient method for 2D single-quantum/single-quantum (1)H/(1)H correlation experiments at ultrafast MAS frequencies. PMID:24713171

Nishiyama, Yusuke; Zhang, Rongchun; Ramamoorthy, Ayyalusamy

2014-06-01

336

Comparison of Inflammatory Events during Developing Immunoglobulin E-Mediated Late-Phase Reactions and Delayed-Hypersensitivity Reactions  

Microsoft Academic Search

To compare cellular and mediator responses in early developing late-phase skin reactions (LPR) and delayed-hypersensitivity (DH) reactions in the same subjects, responses in skin chambers overlying sites of challenge with pollen antigen and Candida albicans antigens were compared in six humans with demonstrated prominent LPR and DH responses. Histamine levels in overlying chamber fluids at 1 h were much higher

BURTON ZWEIMAN; ANNE R. MOSKOVITZ; CAROLYN VON ALLMEN

1998-01-01

337

Design, synthesis and discovery of 1-(2-(6-Chloro-3-methylsulfonyl)-naphthyl)-1H-pyrazole-5-carboxylamides as highly potent factor Xa inhibitors.  

PubMed

Based upon the biphenyl 1-(2-naphthyl)-1H-pyrazole-5-carboxylamides reported in our previous communications, we designed and discovered 2-(6-chloro-3-methylsulfonyl)-naphthyl as an optimal factor Xa S1 binding element. Employing a key Diels-Alder reaction of 1,4-dihydro-2,3-benzoxathiin-3-oxide with maleic anhydride and a key Cu(I)-mediated methylsulfonylation, we prepared two biphenyl 1-(2-(6-chloro-3-methylsulfonyl)-naphthyl)-1H-pyrazole-5-carboxylamides as highly potent factor Xa inhibitors with K(i) values of 0.065 nM and 0.045 nM respectively, and demonstrated the synergistically enhanced binding interaction in the factor Xa S1 site. PMID:19721266

Jia, Zhaozhong Jon; Scarborough, Robert Murry; Zhang, Penglie; Halfon, Sherin; Arfsten, Ann Elizabeth; Sinha, Uma; Zhu, Bing-Yan

2009-09-01

338

Visualizing Infrared (IR) Spectroscopy with Computer Animation  

NASA Technical Reports Server (NTRS)

IR Tutor, an interactive, animated infrared (IR) spectroscopy tutorial has been developed for Macintosh and IBM-compatible computers. Using unique color animation, complicated vibrational modes can be introduced to beginning students. Rules governing the appearance of IR absorption bands become obvious because the vibrational modes can be visualized. Each peak in the IR spectrum is highlighted, and the animation of the corresponding normal mode can be shown. Students can study each spectrum stepwise, or click on any individual peak to see its assignment. Important regions of each spectrum can be expanded and spectra can be overlaid for comparison. An introduction to the theory of IR spectroscopy is included, making the program a complete instructional package. Our own success in using this software for teaching and research in both academic and industrial environments will be described. IR Tutor consists of three sections: (1) The 'Introduction' is a review of basic principles of spectroscopy. (2) 'Theory' begins with the classical model of a simple diatomic molecule and is expanded to include larger molecules by introducing normal modes and group frequencies. (3) 'Interpretation' is the heart of the tutorial. Thirteen IR spectra are analyzed in detail, covering the most important functional groups. This section features color animation of each normal mode, full interactivity, overlay of related spectra, and expansion of important regions. This section can also be used as a reference.

Abrams, Charles B.; Fine, Leonard W.

1996-01-01

339

Detecting explosive substances by the IR spectrography  

NASA Astrophysics Data System (ADS)

Fast and safe detection methods of explosive substances are needed both before and after actualized explosions. This article presents an experiment of the detection of three selected explosives by the ATR FTIR spectrometer and by three different IR hyperspectral imaging devices. The IR spectrometers give accurate analyzing results, whereas hyperspectral imagers can detect and analyze desired samples without touching the unidentified target at all. In the controlled explosion experiment TNT, dynamite and PENO were at first analyzed as pure substances with the ATR FTIR spectrometer and with VNIR, SWIR and MWIR cameras. After three controlled explosions also the residues of TNT, dynamite and PENO were analyzed with the same IR devices. The experiments were performed in arctic outdoor conditions and the residues were collected on ten different surfaces. In the measurements the spectra of all three explosives were received as pure substances with all four IR devices. Also the explosion residues of TNT were found on cotton with the IR spectrometer and with VNIR, SWIR and MWIR hyperspectral imagers. All measurements were made directly on the test materials which had been placed on the explosion site and were collected for the analysis after each blast. Measurements were made with the IR spectrometer also on diluted sample. Although further tests are suggested, the results indicate that the IR spectrography is a potential detection method for explosive subjects, both as pure substances and as post-blast residues.

Kuula, J.; Rinta, Heikki J.; Pölönen, I.; Puupponen, H.-H.; Haukkamäki, Marko; Teräväinen, T.

2014-05-01

340

Nuclear Reactions  

Microsoft Academic Search

Nuclear reactions generate energy in nuclear reactors, in stars, and are\\u000aresponsible for the existence of all elements heavier than hydrogen in the\\u000auniverse. Nuclear reactions denote reactions between nuclei, and between nuclei\\u000aand other fundamental particles, such as electrons and photons. A short\\u000adescription of the conservation laws and the definition of basic physical\\u000aquantities is presented, followed by

C. A. Bertulani; B. Kinematics

2009-01-01

341

Ligand substitution, pH dependent deoxygenation, and linkage isomerization reactions of the 2,2'-bipyridinetetranitroruthenate dianion.  

PubMed

The reaction of the [Ru(bpy)(NO(2))(4)](2-) (bpy = 2,2'-bipyridine) ion in aqueous solutions produces two different nitrosyl complexes, depending on the pH of the solution. At acidic pH, complex cis,cis-Ru(bpy)(NO(2))(2)(ONO)(NO) was isolated. At neutral or basic pH, [Ru(bpy)(NO(2))(4)](2-) reacts to give cis,trans-Ru(bpy)(NO(2))(2)(NO)(OH). Both new complexes were fully characterized by elemental analysis and UV-vis, IR, (1)H NMR, and (15)N NMR spectroscopy. A single-crystal X-ray structure of cis,trans-Ru(bpy)(NO(2))(2)(NO)(OH) was also obtained. cis,cis-Ru(bpy)(NO(2))(2)(ONO)(NO) isomerizes in acetone or water solution to give a mixture of the trans,cis-Ru(bpy)(NO(2))(2)(ONO)(NO) and cis,cis-Ru(bpy)(ONO)(2)(NO(2))(NO) linkage isomers as determined by (1)H and (15)N NMR spectroscopy. A single-crystal X-ray structure of a solid solution of cis,cis-Ru(bpy)(ONO)(2)(NO(2))(NO)/trans,cis-Ru(bpy)(NO(2))(2)(ONO)(NO) was also obtained. This pair of isomers is the first crystallographically characterized compound with nitro, nitrito, and nitrosyl ligands. The kinetic studies of the Ru-NO(2) --> Ru-NO conversion reactions of [Ru(bpy)(NO(2))(4)](2)(-) in buffered solutions from pH 3 to pH 9 complement previous studies of the reverse reaction. The reactions are first order in [Ru(bpy)(NO(2))(4)](2-). At high pH, the reaction is independent of the concentration of H(+) while, at low pH, the reaction is first order in the concentration of H(+). The rate determining step of the high pH reaction involves breakage of the Ru-NO(2) bond while, at low pH, the mechanism involves a rapid reversible protonation of a NO(2) ligand followed by the rate determining loss of hydroxide to produce a nitrosyl ligand. PMID:12132905

Freedman, Daniel A; Janzen, Daron E; Vreeland, Jennifer L; Tully, Hannah M; Mann, Kent R

2002-07-29

342

Elaborated 1H NMR study for the ligitional behavior of two thiosemicarbazide derivatives towards some heavy metals (Sn(II), Sb(III), Pb(II) and Bi(III)), thermal, antibacterial and antifungal studies.  

PubMed

A new series of heavy metal complexes are prepared. Sn(II), Sb(III), Pb(II) and Bi(III) are the metal ions used in complexation with two thiosemicarbazide ligands. The IR and (1)H NMR spectra of the free ligands display their presence in thiole-thione forms coincide with each other. The IR spectra of the complexes support the presence of 2:2 molar ratio (M:HL) with HL(1) ligand and 1:1 beside 1:2 with HL(2). The ligand coordinates as bi molecules in some complexes and displays two tautomer forms at the same complex molecule (1)H NMR spectra of Sn(II) and Sb(III) complexes were done and comes coincide with IR data. The electronic spectral analysis displays a lower shift appearance in n??* charge transfer band in most isolated complexes. As well as, a new band is shinned in visible region with Sb(III), Bi(III) complexes and Sn(II)-HL(2). This band is pointed to its use in spectrophotometric analysis for these metal ions. The TG analysis for all isolated compounds was briefly discussed. The molecular modeling parameters support the stability of thiole form of the free ligands in comparing with their thiones by a small difference. The antibacterial and antifungal activities were studied against some organisms and reveal the priority of most investigated complexes. PMID:21767980

el-Metwaly, Nashwa M; Refat, Moamen S

2011-10-15

343

Structure and catalytic properties of Pt Ir catalysts as a function of different substrate  

NASA Astrophysics Data System (ADS)

A series of Pt-Ir catalysts prepared by the impregnation method in three different supports and different atomic concentrations were characterized by conventional transmission electron microscopy (TEM), high resolution electron microscopy (HREM), X-ray diffraction (XRD) and n-hexane contact reaction as a catalytic probe. The reaction products were grouped in linear (hydrogenolysis products), isomers (2- and 3-methilpentane), cyclic (cyclohexane) and aromatic (benzene) hydrocarbons. An increment in hydrogenolysis products was observed as the amount of Ir was increased. This observation was extreme when Al 2O 3 and SiO 2 were used as supports, but it was not so for the case of TiO 2. From TEM results, it was concluded that the metallic particle size is a function of Ir content. From X-ray diffraction analysis, it was found that a unique crystalline phase containing atoms of Pt and Ir precipitates into the specimens under study. This phase was found to have a face-centered cubic structure and a lattice parameter whose value changes as long as the relative amounts of Pt and Ir does. A linear relationship was observed to hold between the lattice parameter of the precipitated phase and the relative concentration of Pt for specimens with metallic weights of 4 and 8% in a SiO 2 support. This result may be taken as a direct experimental evidence of the fact that the crystalline structure of the phase-centered cubic phase found to precipitate in amorphous silica obeys the Vegard's law and therefore, the character of a solid solution Pt( x) Ir(1- x), where x is the Pt molar fraction, can be assigned to the structural nature of this phase. This new phase and the changes recorded in particle size could explain the changes in selectivity and catalytic activity observed in the n-hexane contact reaction.

Zecua-Fernández, A.; Gómez-Cortés, A.; Cordero-Borboa, A. E.; Vázquez-Zavala, A.

2001-10-01

344

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. PMID:21836875

Wang, Xia; Niu, Jun-long

2011-01-01

345

Bioinspired, cysteamine-catalyzed co-silicification of (1H, 1H, 2H, 2HPerfluorooctyl) triethoxysilane and tetraethyl orthosilicate: formation of superhydrophobic surfaces.  

PubMed

Bioinspired silicification attracts a great deal of interest because of its physiologically relevant, mild conditions for hydrolysis and condensation of silica precursors, which makes the bioinspired approach superior to the conventional sol–gel process, particularly when dealing with biological entities. However, the morphological control of silica structures with incorporation of functional groups in the bioinspired silicilication has been unexplored. In this work, we co-silicificated (1H, 1H, 2H, 2H-perfluorooctyl)triethoxysilane and tetraethyl orthosilicate to investigate the morphological evolution of fluorinated silica structures in the cetyltrimethylammonium bromide-mediated, cysteamine-catalyzed silicification. The generated micrometer-long wormlike and spherical silica structures display superhydrophobicity after film formation. Interestingly, the measurement of dynamic water contact angles shows that the morphological difference leads to a different wetting state, either the self-cleaning or the pinning state of the superhydrophobic surface. PMID:24730056

Park, Ji Hun; Kim, Ji Yup; Cho, Woo Kyung; Choi, Insung S

2014-03-01

346

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

347

Preparation and characterization of S-[2-carboxy-1-(1H-imidazol-4-yl)ethyl]glutathione and its derivatives as proposed precursors of S-[2-carboxy-1-(1H-imidazol-4-yl)ethyl]cysteine, a compound found in human urine.  

PubMed

Formation of 3-[(carboxymethyl)thio]-3-(1H-imidazol-4-yl)propanoic acid (I) and S-[2-carboxy-1-(1H-imidazol-4-yl)ethyl]cysteine (II), compounds found in human urine, has been demonstrated by enzymatic degradation of S-[2-carboxy-1-(1H-imidazol-4-yl)ethyl]glutathione (III). Compound (III) was chemically synthesized in 72% yield by incubating the reaction mixture of trans-urocanic acid and 3-fold excess GSH at 65 degrees C for 1 wk, which was accompanied by formation of N-(S-[2-carboxy-1-(1H-imidazol-4-yl)ethyl]cysteinyl)glycine (IV) in 15% yield. S-[2-Carboxy-1-(1H-imidazol-4-yl)ethyl]-N-gamma-glutamylcysteine (V) was produced by partial hydrolysis of compound (III) in HCl. The synthesized compounds were characterized mainly by fast-atom bombardment mass spectrometry and high-voltage paper electrophoresis as well as chemical degradation. Incubation of compound (III) with rat kidney homogenate in a Tris buffer (pH 8), formed compound (II) in 80% yield possibly via compound (IV). Yield of compound (II) was increased by adding glycylglycine to the reaction mixture. However, little degradation of compound (III) occurred in the use of rat liver, brain, heart or spleen homogenate as the enzyme source. Compound (II) was further metabolized to compound (I) by incubation with rat kidney homogenate in a phosphate buffer of pH 7.4. From these results, we suggest that the urinary compounds are products of enzymatic degradation of compound (III) and that GSH may participate in the metabolism of urocanic acid, the first catabolite of L-histidine. PMID:8507655

Kinuta, M; Ubuka, T; Yao, K; Yamada, S; Yukihiro, K; Tomozawa, M

1993-06-11

348

Complexes with hybrid phosphorus-NHC ligands: pincer-type Ir hydrides, dinuclear Ag and Ir and tetranuclear Cu and Ag complexes.  

PubMed

Three types of hybrid phosphorus-imidazolium salts, 1-methyl-3-(3-((diphenylphosphino)methyl)benzyl)-1H-imidazol-3-ium hexafluorophosphate (2·PF6), 1-methyl-3-(3-(di-tert-butylphosphinooxy)phenyl)imidazolium iodide (8a), and 3-(3-((diphenylphosphoryl)methyl)phenyl)-1-methyl-1H-imidazol-3-ium iodide (11) have been prepared and used as precursors to phosphine-NHC, phosphinite-NHC, and phosphoryl-NHC metal complexes, respectively. The structure of 11 has been determined by X-ray diffraction. The Ag(I) and Ir(I) complexes of the phosphine-NHC ligand, [Ag(?-P-NHC,?C,?P)]2(PF6)2 (3) and [Ir(cod)(?-P-NHC,?C,?P)]2(PF6)2 (4), were obtained and characterized by NMR, ESI-MS, elemental analysis, and X-ray diffraction. Both complexes are dinuclear and dicationic, with two P-NHC ligands bridging the two metal centers. The presence of the P donor led for 3 to an unprecedented structure compared to that of related Ag(I) complexes with trans spanning bis-NHC ligands. Complex 4 is the first example of a dinuclear iridium complex with a hybrid P-NHC ligand. The new hydrido, Ir(III) pincer-type complex [IrH(CNHCCCNHC)(MeCN)]PF6 (7) is suggested to have a square-pyramidal structure. The tetranuclear Ag(I) complex with the phosphinite-NHC ligand, [Ag2(?3-I)(?-PO-NHC,?P,?CNHC)]2 (9a) has a cubane-type structure, with alternating silver and iodine apexes and two PO-NHC ligands bridging opposite edges of the Ag4 tetrahedron. The Ir(III) pincer complexes [IrH(I)(PO-NHC,?P,?C,?CNHC)(Me)] (10a) and [IrH(I)(PO-NHC,?P,?C,?CNHC)(n-Bu)] (10b), with Me or n-Bu substituents on the nitrogen atom, respectively, have been prepared and characterized. Ag(I) and Cu(I) complexes with the phosphoryl-NHC ligand are reported and the centrosymmetric structure of the latter, [Cu(OP-NHC,?CNHC)2(?-I){Cu(?-I)}]2 (13), was established by X-ray diffraction and consists of a central Cu2(?-I)2 rhombus connected by single iodide bridges to two Cu(OP-NHC,?CNHC)2 moieties. The Ir(III) hydride pincer complexes 10a,b were tested as catalyst precursors for the C-H bond activation of alkanes. Although their efficiency was significantly lower for transfer dehydrogenation from cyclooctane (coa) to t-butylethylene (tbe) than that of known PCP-Ir systems, these results represent the first attempts to study the catalytic properties of hybrid P-NHC iridium pincer complexes. PMID:23750783

Liu, Xianghao; Braunstein, Pierre

2013-07-01

349

Higgs phenomenology in Type-I 2HDM with U(1) H Higgs gauge symmetry  

NASA Astrophysics Data System (ADS)

It is well known that generic two-Higgs-doublet models (2HDMs) suffer from potentially large Higgs-mediated flavor-changing neutral current (FCNC) problem, unless additional symmetries are imposed on the Higgs fields thereby respecting the Natural Flavor Conservation Criterion (NFC) by Glashow and Weinberg. A common way to respect the NFC is to impose Z 2 symmetry which is softly broken by a dim-2 operator. Another new way is to introduce local U(1) H Higgs flavor symmetry that distinguishes one Higgs doublet from the other. In this paper, we consider the Higgs phenomenology in Type-I 2HDMs with the U(1) H symmetry with the simplest U(1) H assignments that the SM fermions are all neutral under U(1) H , and we make detailed comparison with the ordinary Type-I 2HDM. After imposing various constraints such as vacuum stability and perturbativity as well as the electroweak precision observables and collider search bounds on charged Higgs boson, we find that the allowed Higgs signal strengths in our model are much broader than those in the ordinary Type-I 2HDM, because of newly introduced U(1) H -charged singlet scalar and U(1) H gauge boson. Still the ATLAS data on gg ? h ? ?? cannot be accommodated. Our model could be distinguished from the ordinary 2HDM with the Z 2 symmetry in a certain parameter region and some channels. If the couplings of the new boson turn out to be close to those in the SM, it would be essential to search for extra U(1) H gauge boson and/or one more neutral scalar boson to distinguish two models.

Ko, P.; Omura, Yuji; Yu, Chaehyun

2014-01-01

350

Mid-IR supercontinuum generation and applications: a review  

NASA Astrophysics Data System (ADS)

In this paper, a review on mid-IR supercontinuum generation (SCG) and its applications is presented. First, the physical mechanism of the supercontinuum generation in IR crystal fiber is introduced. Second, the recent progress on IR single crystal fiber, in particular ultrathin core double cladding IR single crystal fiber is described. Third, the transmission characteristics of mid-IR crystal fiber is illustrated. Fourth, the mid-IR supercontinuum generation in IR single crystal fiber is presented. Finally, the application of IR supercontinuum for smart target recognition is illustrated

Yin, Shizhuo; Ruffin, Paul; Brantley, Christina; Edwards, Eugene; Luo, Claire

2014-09-01

351

Reaction Time  

NSDL National Science Digital Library

In this activity, learners explore reaction time and challenge themselves to improve their coordination. Do you want to move faster? Catch that ball that you never seem to see in time? Use a simple test to help you improve your reaction (or response) time.

Science, New Y.

1999-01-01

352

Non-classical transformation of benzendiazonium hydrogen sulfates. Access to 1,3-dimethylisochromeno[4,3-c]pyrazol-5(1H)-one, a potential benzodiazepine receptor ligand.  

PubMed

The compound 2-((1,3-dimethyl-1H-pyrazol-5-yl)(methyl)carbamoyl)benzene-diazonium hydrogen sulfate (10) was reacted with copper sulfate and sodium chloride, in the presence of ascorbic acid as reducing agent, to afford a mixture of the chlorinated epimers 4'-chloro-2,2',5'-trimethyl-2',4'-dihydrospiro[isoindoline-1,3'-pyrazol]-3-one (18) and (19), the epimers 4'-hydroxy-2,2',5'-trimethyl-2',4'-dihydrospiro[isoindoline-1,3'-pyrazol]-3-one (20) and (21), and N-(1,3-dimethyl-1H-pyrazol-5-yl)benzamide (22). Under the foregoing conditions, diazonium salt 10 affords neither the 2-chloro-N-(1,3-dimethyl-1H-pyrazol-5-yl)-N-methylbenzamide (23) nor the tricyclic derivative 24, the classical products of the Sandmeyer and Pschorr reactions, respectively. Finally, by heating 20 at 210 °C the compound 1,3-dimethylisochromeno[4,3-c]pyrazol-5(1H)-one (24) was obtained. The transformation under the above conditions of 2-((4-chloro-3-methyl-1-phenyl- 1H-pyrazol-5-yl)(methyl)carbamoyl)benzendiazonium hydrogen sulphate (11) afforded 4',4'-dichloro-2,5'-dimethyl-2'-phenyl-2',4'-dihydrospiro[isoindoline-1,3'-pyrazol]-3-one (29) as the sole reaction product. PMID:24152597

Maggio, Benedetta; Raffa, Demetrio; Raimondi, Maria Valeria; Daidone, Giuseppe

2013-01-01

353

IR Free or Interacting? A Proposed Diagnostic  

E-print Network

We present and discuss a conjectured criterion for determining whether a 4d quantum field theory is IR free, or flows to an interacting conformal field theory in the infrared: ``the correct infrared phase is that with the larger conformal anomaly $a$". A stronger conjecture is that ``an operator can become IR free only if that results in a larger conformal anomaly $a$". We test these conjectures in the context of N=1 supersymmetric theories. They are verified to indeed predict the correct IR phase in every tested case, for a plethora of examples for which the infrared phase could already be determined on other grounds. When applied to the still unsettled case of SU(2) with a chiral superfield in the isospin 3/2 representation, the conjecture suggest that the IR phase is conformal rather than confining.

Kenneth Intriligator

2005-09-12

354

Pilietinis nepaklusnumas ir demokratija: socioedukacin? dimensija.  

E-print Network

??Magistro darbe analizuojama pilietinio ugdymo/nepaklusnumo proces? ir form? raiška besiformuojan?ioje pilietin?je visuomen?je. Tyrimu siekiama pagr?sti pilietinio nepaklusnumo paradigm? valstybi? kov? už nepriklausomyb? kontekste, ?vertinti j?… (more)

Butkevi?ius,; Audrius

2012-01-01

355

Far-IR selected star formation regions  

NASA Technical Reports Server (NTRS)

Detailed far-IR observations and complemenary submillimeter, 5 GHz continuum and c(18)0 observations of a sample of far-IR selected luminous regions of star formation. The clouds and that the exciting stars lie deep within these condensations. The far-IR sources have diversely shaped 40 micron to 180 micron spectra even through their 60 micron to 100 micron color temperatures are similar. The radio and far-IR results together show that the exciting stars are in clusters containing either zero-age main sequence and pre-main sequence stars or consisting entirely of premain sequence objects. C(18)0 and submillimeter observations imply gas densities approximately .00005 - high enough to make t(sub dust) approximately t(sub gas).

Jaffe, D. T.; Hildebrand, R. H.; Keene, J.; Harper, D. A.; Loewenstein, R. F.; Moran, J. M.

1984-01-01

356

Chemical Reactions  

NSDL National Science Digital Library

We are going go over a general view of reactions to prepare us for our unit on Chemical Reactions! Have fun learning! WARNING: If you are caught looking at ANY other site, without permission, you will be sent to the ALC, and you will not participate in any other computer activities for the rest of the year. Get your worksheet and begin! Overview Take this quiz and have me come over and sign off on your worksheet when you have completed the quiz! Overview Quiz Next let's take a look at what effect the rate of a chemical reaction. Rates of Reactions Another quiz, another check off by me! Rates of Reactions Quiz Now how do we measure how fast a ...

Hicken, Mrs.

2009-05-04

357

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

358

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

359

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

360

Gale Crater in IR Color  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

Released August 4, 2004 This image shows two representations of the same infra-red image of Gale Crater. On the left is a grayscale image showing surface temperature, and on the right is a false-color composite made from 3 individual THEMIS bands. The false-color image is colorized using a technique called decorrelation stretch (DCS), which emphasizes the spectral differences between the bands to highlight compositional variations.

In the bottom of the crater, surrounding the central mound, there are extensive basaltic sand deposits. The basaltic sand spectral signature combined with the warm surface (due to the low albedo of basaltic sand) produces a very strong pink/magenta color. This color signature contrasts with the green/yellow color of soil and dust in the top of the image, and the cyan color due to the presence of water ice clouds at the bottom of the image. This migrating sand may be producing the erosional features seen on the central mound.

Image information: IR instrument. Latitude -4.4, Longitude 137.4 East (222.6 West). 100 meter/pixel resolution.

Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

2004-01-01

361

Atmospheric Effects in IR Color  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

Released August 3, 2004 This image shows two representations of the same infra-red image covering parts of Ius Chasma and Oudemans Crater. On the left is a grayscale image showing surface temperature, and on the right is a false-color composite made from 3 individual THEMIS bands. The false-color image is colorized using a technique called decorrelation stretch (DCS), which emphasizes the spectral differences between the bands to highlight compositional variations.

This image is dominated by atmospheric effects. The pink/magenta colors inside the canyon show areas with a large amount of atmospheric dust. In the bottom half of the image, the patchy blue/cyan colors indicate the presence of water ice clouds out on the plains. Water ice clouds and high amounts of dust do not generally occur at the same place and time on Mars because the dust absorbs sunlight and heats the atmosphere. The more dust that is present, the warmer the atmosphere becomes, sublimating the water ice into water vapor and dissipating any clouds.

Image information: IR instrument. Latitude -8.2, Longitude 267.9 East (92.1.West). 100 meter/pixel resolution.

Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

2004-01-01

362

Noninvasive quantification of hepatic steatosis inrats using 3.0 T (1)H-magnetic resonance spectroscopy  

Microsoft Academic Search

PURPOSE:: To assess the accuracy of noninvasive 3.0 T (1)H-magnetic resonance spectroscopy ((1)H-MRS) in an experimental steatosis model for the discrimination of clinically relevant macrovesicular steatosis degrees and to evaluate three different (1)H-MR spectrum-based fat quantification methods. MATERIALS AND METHODS:: Steatosis was induced in rats by a methionine\\/choline-deficient diet for 0-5 weeks. (1)H-MRS measurements of hepatic fat content were compared

H. A. Marsman; Werven van J. R; A. J. Nederveen; Kate ten F. J; M. Heger; J. Stoker; Gulik van T. M

2010-01-01

363

Molecular structure, vibrational spectra and (13)C and (1)H NMR spectral analysis of 1-methylnaphthalene by ab initio HF and DFT methods.  

PubMed

The Fourier transform infrared (FT-IR) and FT-Raman of 1-methylnaphthalene (1MN) have been recorded and analyzed. The equilibrium geometry, bond lengths, bond angles and harmonic vibrational frequencies have been investigated with the help of density functional theory (DFT) method. Vibrational spectroscopic assignments of 1-methylnaphthalene (1MN) are carried out with the help of quantum chemical calculation. The (1)H and (13)C nuclear magnetic resonance (NMR) chemical shifts of the molecule are calculated by the Gauge including atomic orbital (GIAO) method. The molecular stability and bond strength have been investigated by using natural bond orbital analysis (NBO). The assignments of vibrational spectra have been carried out with the help of normal co-ordinate analysis (NCA) following the scaled quantum mechanical force field (SQMFF) methodology. The (1)H and (13)C nuclear magnetic resonance (NMR) chemical shift of the molecular is depend only on the structure of the molecule. The calculated HOMO and LUMO energy shows that charge transfer interactions take place within the molecule. Finally, the calculation results are applied to simulate infrared and Raman spectra of the title compound which show good agreement with observed spectra. PMID:24996214

Shailajha, S; Rajesh Kannan, U; Sheik Abdul Kadhar, S P; Isac Paulraj, E

2014-12-10

364

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

365

Crystal structure and DFT calculations of 5-(4-Chlorophenyl)-1-(6-methoxypyridazin-3-yl)-1H-pyrazole-3-carboxylic acid  

NASA Astrophysics Data System (ADS)

The title compound, 5-(4-Chlorophenyl)-1-(6-methoxypyridazin-3-yl)-1H-pyrazole-3-carboxylic acid, has been characterized by using elemental analysis, MS, FT-IR, 1H NMR and 13C NMR spectroscopic, and crystallographic techniques. The title compound crystallizes in the triclinic space group P-1 with a = 9.612(1), b = 9.894(1), c = 17.380(1) Å, ? = 90.213(5)°, ? = 104.99(1)°, ? = 111.072(5)°, V = 1481.3(2) Å3 and Dx = 1.483 g cm-3 respectively. The structure of the compound has also been examined by using quantum chemical methods. The molecular geometry and vibrational frequencies of monomeric and dimeric form of the title compound in the ground state have been calculated by using the B3LYP/6-31G(d,p) level of the theory. The calculated results show that the optimized geometry and the theoretical vibration frequencies of the dimeric form are good agreement with experimental data. In addition, HOMO-LUMO energy gap, molecular electrostatic potential map, thermodynamic properties of the title compound were performed at B3LYP/6-31G(d,p) level of theory.

Ala?alvar, Can; Soylu, Mustafa Serkan; Ünver, Hüseyin; Ocak ?skeleli, Nazan; Yildiz, Mustafa; Çiftçi, Murat; Bano?lu, Erden

2014-11-01

366

Synthesis, spectroscopic characterization and crystal structure of 5-bromo-1-(2-cyano-pyridin-4-yl)-1 H-indazole-3-carboxylic acid diethylamide  

NASA Astrophysics Data System (ADS)

The title compound 5-bromo-1-(2-cyano-pyridin-4-yl)-1 H-indazole-3-carboxylic acid diethylamide, C18H16BrN5O, is prepared from 5-bromoindazole-3-carboxylic acid methylester. N 1-arylation is carried out with 4-chloro-2-cyanopyridine and the resulting product is converted to diethylamide by reacting with thionyl chloride and diethylamine. The structure is identified from its FT-IR, 1H NMR, 13C NMR spectroscopy, elemental analysis data and unambiguously confirmed by single crystal X-ray diffraction studies. There are two symmetry independent molecules in the asymmetric unit with no significant differences in bond lengths and angles. The title compound crystallizes in the triclinic system, space group , with a = 11.2330(2); b = 11.6130(2); c = 15.4710(3) Å, ? = 92.515(1)°; ? = 109.956(1)°; ? = 107.199(1)°; V = 1788.45(6)Å3 and z = 4. An intramolecular C-H…N hydrogen bond forms an S(6) ring motif in one of the unique molecules. In the crystal, two molecules are linked about a center of inversion by C-H…O hydrogen bonded dimers generating an R {2/2}(16) ring motif. The crystal packing is stabilized by C-H…N, C-H…O hydrogen bonds and ?…? stacking interactions.

Anuradha, G.; Vasuki, G.; Surendrareddy, G.; Veerareddy, A.; Dubey, P. K.

2014-07-01

367

Molecular structure, vibrational spectra and 13C and 1H NMR spectral analysis of 1-methylnaphthalene by ab initio HF and DFT methods  

NASA Astrophysics Data System (ADS)

The Fourier transform infrared (FT-IR) and FT-Raman of 1-methylnaphthalene (1MN) have been recorded and analyzed. The equilibrium geometry, bond lengths, bond angles and harmonic vibrational frequencies have been investigated with the help of density functional theory (DFT) method. Vibrational spectroscopic assignments of 1-methylnaphthalene (1MN) are carried out with the help of quantum chemical calculation. The 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule are calculated by the Gauge including atomic orbital (GIAO) method. The molecular stability and bond strength have been investigated by using natural bond orbital analysis (NBO). The assignments of vibrational spectra have been carried out with the help of normal co-ordinate analysis (NCA) following the scaled quantum mechanical force field (SQMFF) methodology. The 1H and 13C nuclear magnetic resonance (NMR) chemical shift of the molecular is depend only on the structure of the molecule. The calculated HOMO and LUMO energy shows that charge transfer interactions take place within the molecule. Finally, the calculation results are applied to simulate infrared and Raman spectra of the title compound which show good agreement with observed spectra.

Shailajha, S.; Rajesh Kannan, U.; Sheik Abdul Kadhar, S. P.; Isac Paulraj, E.

2014-12-01

368

Hematocrit and oxygenation dependence of blood (1)H(2)O T(1) at 7 Tesla.  

PubMed

Knowledge of blood (1)H2O T1 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)H2O T1 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)H2O R1 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 T1 = 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)H2O T1 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 (pO2) and the effect of plasma osmolality for different anticoagulants were also investigated. It is discussed why blood (1)H2O T1 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. PMID:23169066

Grgac, Ksenija; van Zijl, Peter C M; Qin, Qin

2013-10-01

369

5-Phenyl-1-H-Tetrazole as a Low-pH Passivating Agent for Copper Chemical Mechanical Planarization  

E-print Network

5-Phenyl-1-H-Tetrazole as a Low-pH Passivating Agent for Copper Chemical Mechanical Planarization mechanical planarization CMP . An alternative passivation agent, 5-phenyl-1H-tetrazole PTA , is proposed here-10 The focus of the current investigation is 5-phenyl-1H-tetrazole PTA , whose molecular structure is shown

Suni, Ian Ivar

370

Near-IR/optical monitoring programme of the 'Arecibo sample of OH/IR stars'  

E-print Network

We performed a near-IR/optical monitoring programme from 1999 to 2005 in order to study the variability properties of the 'Arecibo sample of OH/IR stars' (periods, amplitudes, and colour variations). Here we describe this multi-wavelength long-term monitoring programme. Data analysis is still in process. Our ultimate goal is to study in particular the oxygen-rich AGB stars with masses larger than 2 Solar Mass, which are probably rare among AGB stars discovered optically and/or in the near-IR, but are common in samples discovered in the mid- to far-IR.

Francisco Jiménez-Esteban; Dieter Engels; Pedro García-Lario

2006-10-31

371

Near-IR spectroscopy of OH/IR stars in the Galactic Centre  

E-print Network

Context. Galactic Centre (GC) OH/IR stars can be, based on the expansion velocities of their circumstellar shells, divided into two groups which are kinematically different and therefore are believed to have evolved from different stellar populations. Aims. To study the metallicity distribution of the OH/IR stars population in the GC on basis of a theoretical relation between EW(Na), EW(Ca) and EW(CO) and the metallicity. Methods. For 70 OH/IR stars in the GC, we obtained near-IR spectra. The equivalent line widths of NaI, CaI, 12CO(2,0) and the curvature of the spectrum around 1.6 micron due to water absorption are determined. Results. The near-IR spectrum of OH/IR stars is influenced by several physical processes. OH/IR stars are variable stars suffering high mass-loss rates. The dust that is formed around the stars strongly influences the near-IR spectra and reduces the equivalent line widths of NaI, CaI. A similar effect is caused by the water content in the outer atmosphere of the OH/IR star. Because of these effects, it is not possible with our low resolution near-infrared spectroscopy to determine the metallicities of these stars.

E. Vanhollebeke; J. A. D. L. Blommaert; M. Schultheis; B. Aringer; A. Lancon

2006-04-28

372

Radical scavenging capacity of 2,4-dihydroxy-9-phenyl-1H-phenalen-1-one: a functional group exclusion approach.  

PubMed

2,4-Dihydroxy-9-phenyl-1H-phenalen-1-one (4-hydroxyanigorufone, 1), a compound isolated from Anigozanthos flavidus and Monochoria elata, displayed a high radical scavenging capacity in the ORAC assay. A systematic approach was adopted in order to explore the effect of each functional group. H-Atom transfer from the phenolic hydroxyl, a captodative effect from the hydroxy ketone, and the presumed involvement of the phenyl ring in the termination step of the radical reaction were disclosed as relevant features of this type of antioxidant. PMID:23834597

Duque, Luisa; Zapata, Carolina; Rojano, Benjamín; Schneider, Bernd; Otálvaro, Felipe

2013-07-19

373

Synthesis, structure, optical properties, antifungal and antibacterial activities of 2-(1-oxo-1H-2,3-dihydroisoindol-2-yl)-3-imidazolyl-L-lactamic acid  

NASA Astrophysics Data System (ADS)

2-(1-oxo-1H-2,3-dihydroisoindol-2-yl)-3-imidazolyl-L-lactamic acid has been prepared conveniently by the condensation reaction of o-phthalaldehyde (OPA) with L-Histidine, and its single crystal structure has been characterized by X-ray crystallography method. The in vitro antifungal and antibacterial activities of the compound were investigated with the representative strains of Candida albicans, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. Its luminescent and nonlinear optical properties have also been investigated. Second-harmonic-generation (SHG) measurements indicate that compound 1 displays a weak SHG response of about 0.75 times that of KH2PO4.

Jia, Ting; Zhang, Wei-Long; Chen, Yun; Cai, Shuang-Lian; Yi, Hai-Bo

2013-10-01

374

Double-tuned Radiofrequency Coil for (19)F and (1)H Imaging.  

PubMed

We developed a double-tuned radiofrequency (RF) coil using a novel circuit method to double tune for fluorine-19 ((19)F) and (1)H magnetic resonance imaging, whose frequencies are very close to each other. The RF coil consists of 3 parallel-connected series inductor capacitor circuits. A computer simulation for our double-tuned RF coil with a phantom demonstrated that the coil has tuned resonant frequency and high sensitivity for both (19)F and (1)H. Drug distribution was visualized at 7 tesla using this RF coil and a rat administered perfluoro 15-crown-5-ether emulsion. The double-tune RF coil we developed may be a powerful tool for (19)F and (1)H imaging. PMID:24990464

Otake, Yosuke; Soutome, Yoshihisa; Hirata, Koji; Ochi, Hisaaki; Bito, Yoshitaka

2014-09-29

375

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

376

DFT studies of structure and vibrational spectra of 4-benzylidene-1-phenyl-2-selenomorpholino-1H-imidazol-5(4H)-one and its derivatives  

NASA Astrophysics Data System (ADS)

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 30cm-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 Cdbnd 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.

Zhou, Shuli; You, Bin; Yao, Qi; Chen, Meng; Wang, Yujiao; Li, Wei

2013-06-01

377

Low-E probe for (19)F-(1)H NMR of dilute biological solids.  

PubMed

Sample heating induced by radio frequency (RF) irradiation presents a significant challenge to solid state NMR experiments in proteins and other biological systems, causing the sample to dehydrate which may result in distorted spectra and a damaged sample. In this work we describe a large volume, low-E (19)F-(1)H solid state NMR probe, which we developed for the 2D (19)F CPMG studies of dilute membrane proteins in a static and electrically lossy environment at 600MHz field. In (19)FCPMG and related multi-pulse (19)F-(1)H experiments the sample is heated by the conservative electric fields E produced in the sample coil at both (19)F and (1)H frequencies. Instead of using a traditional sample solenoid, our low-E (19)F-(1)H probe utilizes two orthogonal loop-gap resonators in order to minimize the conservative electric fields responsible for sample heating. Absence of the wavelength effects in loop-gap resonators results in homogeneous RF fields and enables the study of large sample volumes, an important feature for the dilute protein preparations. The orthogonal resonators also provide intrinsic isolation between the (19)F and (1)H channels, which is another major challenge for the (19)F-(1)H circuits where Larmor frequencies are only 6% apart. We detail steps to reduce (19)F background signals from the probe, which included careful choice of capacitor lubricants and manufacture of custom non-fluorinated coaxial cables. Application of the probe for two-dimensional (19)F CPMG spectroscopy in oriented lipid membranes is demonstrated with Flufenamic acid (FFA), a non-steroidal anti-inflammatory drug. PMID:17920316

Gor'kov, Peter L; Witter, Raiker; Chekmenev, Eduard Y; Nozirov, Farhod; Fu, Riqiang; Brey, William W

2007-12-01

378

Comparing A^1-h-cobordism and A^1-weak equivalence.  

E-print Network

We study the problem of classifying projectivizations of rank-two vector bundles over ${\\mathbb P}^2$ up to various notions of equivalence that arise naturally in ${\\mathbb A}^1$-homotopy theory, namely ${\\mathbb A}^1$-weak equivalence and ${\\mathbb A}^1$-$h$-cobordism. First, we classify such varieties up to ${\\mathbb A}^1$-weak equivalence: over algebraically closed fields having characteristic unequal to two the classification can be given in terms of characteristic classes of the underlying vector bundle. When the base field is ${\\mathbb C}$, this classification result can be compared to a corresponding topological result and we find that the algebraic and topological homotopy classifications agree. Second, we study the problem of classifying such varieties up to ${\\mathbb A}^1$-$h$-cobordism using techniques of deformation theory. To this end, we establish a deformation rigidity result for ${\\mathbb P}^1$-bundles over ${\\mathbb P}^2$ which links ${\\mathbb A}^1$-$h$-cobordisms to deformations of the underlying vector bundles. Using results from the deformation theory of vector bundles we show that if $X$ is a ${\\mathbb P}^1$-bundle over ${\\mathbb P}^2$ and $Y$ is the projectivization of a direct sum of line bundles on ${\\mathbb P}^2$, then if $X$ is ${\\mathbb A}^1$-weakly equivalent to $Y$, $X$ is also ${\\mathbb A}^1$-$h$-cobordant to $Y$. Finally, we discuss some subtleties inherent in the definition of ${\\mathbb A}^1$-$h$-cobordism. We show, for instance, that direct ${\\mathbb A}^1$-$h$-cobordism fails to be an equivalence relation.

Aravind Asok; Stefan Kebekus; Matthias Wendt

379

1H and 13C NMR assignments for the cyanine dyes SYBR Safe and thiazole orange.  

PubMed

Analysis of (1)H and (13)C NMR and mass spectral data for the fluorescent nucleic acid stain SYBR Safe indicates that it contains a cyanine-based cationic core structure identical to thiazole orange. The difference between these two compounds is the type of N-substitution on the quinolinium ring system (SYBR Safe, n-Pr; thiazole orange, Me). The (1)H and (13)C NMR resonances for both compounds were assigned on the basis of one- and two-dimensional (COSY, ROESY, HSQC, and HMBC) experiments. The preferred conformation of these compounds was computed by ab initio methods and found to be consistent with the NMR data. PMID:23137048

Evenson, William E; Boden, Lauren M; Muzikar, Katy A; O'Leary, Daniel J

2012-12-01

380

Proton Fingerprints Portray Molecular Structures: Enhanced Description of the 1H NMR Spectra of Small Molecules  

PubMed Central

The characteristic signals observed in NMR spectra encode essential information on the structure of small molecules. However, extracting all of this information from complex signal patterns is not trivial. This report demonstrates how computer-aided spectral analysis enables the complete interpretation of 1D 1H NMR data. The effectiveness of this approach is illustrated with a set of organic molecules, for which replicas of their 1H NMR spectra were generated. The potential impact of this methodology on organic chemistry research is discussed. PMID:24007197

Napolitano, Jose G.; Lankin, David C.; McAlpine, James B.; Niemitz, Matthias; Korhonen, Samuli-Petrus; Chen, Shao-Nong; Pauli, Guido F.

2013-01-01

381

Inclusion complex of benzocaine and ?-cyclodextrin: 1H NMR and isothermal titration calorimetry studies  

NASA Astrophysics Data System (ADS)

The supramolecular structure of the inclusion complex of ?-cyclodextrin with benzocaine in aqueous solution has been investigated by 1H NMR spectroscopy and isothermal titration nanocalorimetry (ITC). Analysis of 1H NMR data by continuous variation method indicates that the benzocaine: ?-cyclodextrin inclusion complex occurs and has a 1:1 stoichiometry. Rotating frame NOE spectroscopy (ROESY) was used to ascertain the solution geometry of the host-guest complex which indicates that the benzocaine molecule was included with the aromatic ring into the cyclodextrin cavity. Although the affinity of benzocaine for cyclodextrin is relatively high, the association constant cannot be measured using ITC due to the low solubility of benzocaine in water.

Mic, Mihaela; P?rn?u, Adrian; Bogdan, Mircea; Turcu, Ioan

2013-11-01

382

1H NMR study of inclusion compounds of phenylurea derivatives in ?-cyclodextrin  

NASA Astrophysics Data System (ADS)

Proton nuclear magnetic resonance spectroscopy ( 1H NMR), which has become an important tool for the study "in situ" of ?-cyclodextrin (?-CD) complexes, was used to study and structurally characterize the inclusion complexes formed between ?-CD and isoproturon, fenuron, monuron and diuron. The high variation of the chemical shifts from the proton located inside the cavity (H-3, H-5 and H-6) coupled with the non variation of the one located outer sphere of the ?-CD (H-1, H-2 and H-4) provided clear evidence of the inclusion phenomena. Two-dimensional rotating frame Overhauser effect spectroscopy (ROESY) experiments were carried out to further support the proposed inclusion mode.

Dupuy, N.; Barbry, D.; Bria, M.; Marquis, S.; Vrielynck, L.; Kister, J.

2005-04-01

383

Fourier Transform Infrared (FT-IR) Spectroscopy of Atmospheric Trace Gases HCl, NO and SO2  

NASA Technical Reports Server (NTRS)

Fourier Transform Infrared (FT-IR) spectral data have been recorded in the spectral region 400-4000/cm of hydrogen chloride and sulfur dioxide with I/cm resolution and of nitric oxide with 0.25 cm-i resolution, under quasi-static conditions, when the sample gas was passed through tubings of aluminum, copper, stainless steel and teflon. The absorbance was measured for the rotational lines of the fundamental bands of (1)H(35)Cl and (1)H(37)Cl for pressures in the range 100-1000 Torr and for the (14)N(16)O molecule in the range 100-300 Torr. The absorbance was also measured for individual rotational lines corresponding to the three modes of vibrations (upsilon(sub 1) - symmetric stretch, upsilon(sub 2) - symmetric bend, upsilon(sub 3) - anti-symmetric stretch) of the SO2 molecule in the pressure range 25-150 Torr. A graph of absorbance versus pressure was plotted for the observed rotational transitions of the three atmospherically significant molecules, and it was found that the absorbance was linearly proportional to the pressure range chosen, thereby validating Beer's law. The absorption cross-sections were determined from the graphical slopes for each rotational transition recorded for the HCl, NO and SO2 species. Qualitative and quantitative spectral changes in the FT-IR data will be discussed to identify and characterize various tubing materials with respect to their absorption features.

Haridass, C.; Aw-Musse, A.; Dowdye, E.; Bandyopadhyay, C.; Misra, P.; Okabe, H.

1998-01-01

384

Solid-state NMR structure characterization of a 13CO-Labeled Ir(I) complex with a P,N-donor ligand including ultrafast MAS methods.  

PubMed

The structural characterization of a (13)CO-labeled Ir(I) complex bearing an P,N-donor ligand (1-[2-(diphenylphosphino)ethyl]pyrazole), [Ir(PyP)((13)CO)Cl] is demonstrated using a series of tailored solid-state NMR techniques based on ultrafast (60 kHz) Magic Angle Spinning (MAS), which facilitates correlations with narrow proton line-widths. Our 1D (1)H MAS and 2D (13)C and (31)P CP-MAS NMR spectra provided structural information similar to that obtained using NMR spectroscopy in solution. We employed high-resolution 2D solid-state correlation spectroscopy ((1)H-(13)C HETCOR, (1)H-(31)P correlation) to characterize the networks of dipolar couplings between protons and carbon/phosphorus. (1)H-(1)H SQ-SQ correlation spectra showed the dipolar contacts between all protons in a similar fashion to its solution counterpart, NOESY. The use of the (1)H single quantum/double quantum experiments made it possible to observe the dipolar-coupling contacts between immediately adjacent protons. Additionally, internuclear (13)CO-(31)P distance measurements were performed using REDOR. The combination of all of these techniques made it possible to obtain comprehensive structural information on the molecule [Ir(PyP)((13)CO)Cl] in the solid state, which is in excellent agreement with the single crystal X-ray structure of the complex, and demonstrates the enormous value of ultrafast MAS NMR techniques for a broad range of future applications. PMID:24992359

Tregubov, Andrey A; Linser, Rasmus; Vuong, Khuong Q; Rawal, Aditiya; Gehman, John D; Messerle, Barbara A

2014-07-21

385

Allergic Reactions  

MedlinePLUS

... For instance, if you have an allergy to pollen, your immune system identifies pollen as an invader or allergen . Your immune system ... it can affect a child's speech and language development. Diagnosing and Treating Allergic Reactions An allergist / immunologist, ...

386

Drug Reactions  

MedlinePLUS

Most of the time, medicines make our lives better. They reduce aches and pains, fight infections, and control problems such as high blood pressure or diabetes. But medicines can also cause unwanted reactions. One problem is ...

387

Solid-state 1H NMR in 1-propyl-1H-tetrazole complexes of iron(II) and zinc(II)  

NASA Astrophysics Data System (ADS)

PMR linewidths (??) and spin-lattice relaxation times ( T1) were measured on [M(1- n-propyl-1H-tetrazole) 6](BF 4) 2 (M is Zn or Fe). Three motional minima of T1 associated with steps of ?? were found, and a structural change in the temperature region of 100 to 120 K is suggested in the zinc complex. The spin transition temperature was found to be ˜130 K, and an anomalous minimum of T1 occurred at 9 K in the iron complex.

Bokor, Mónika; Marek, Tamás; Tompa, Kálmán; Vértes, Attila

1997-06-01

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 N1sbnd H29⋯N9 between pyrrole Nsbnd H 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 Nsbnd H 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

A large perturbation on electronic and photophysical properties of Ir(III) carbene complexes caused by the variation of N-substitution in N,N?-heteroaromatic ligands  

NASA Astrophysics Data System (ADS)

DFT/TDDFT investigation was performed on the electronic and photophysical properties of blue-emitting Ir(III) carbene complexes (fpmi)3-xIr(N^N?)x (x = 1, 2) [fpmi = 1-(4-fluorophenyl)-3-methylimidazolin-2-ylidene-C,C2?, N^N? = 2-(1H-pyrazol-5-yl)pyridinato (1a(x = 1)/1a?(x = 2)); 2-(1H-imidazol-5-yl)pyridinato (1b/1b?); 2-(1H-imidazol-2-yl)pyridinato (1c/1c?); 2-(1H-1,2,4-triazol-5-yl)pyridinato (2a/2a?); 2-(1H-1,2,3-triazol-5-yl)pyridinato (2b/2b?); 2-(4H-1,2,4-triazol-3-yl)pyridinato (2c/2c?)]. The absorption intensities and band positions are obviously affected by the variation of N substitution in N^N? ligand. The emission properties show an apparent dependence on the solvent effects, and the N^N? ligand plays an important role in governing the emissive state. The pyrazolyl-pyridyl-based N^N? ligand is considered to be more beneficial for blue OLEDs emitters.

Liu, Yuqi; Si, Yanling; Wang, Ying; Wu, Zhijian

2014-08-01

390

Chloro- fac-tricarbonylrhenium(I) complexes of asymmetric azines derived from 6-acetyl-1,3,7-trimethylpteridine-2,4(1 H,3 H)-dione with hydrazine and aromatic aldehydes: Preparation, structural characterization and biological activity against several human tumor cell lines  

Microsoft Academic Search

A number of new asymmetric azines derived from hydrazine and 6-acetyl-1,3,7-trimethyllumazine (lumazine=pteridine-2,4(1H,3H)-dione) and its derivatives with several aromatic aldehydes have been prepared and characterized by usual procedures (XRD, IR, 1H and 13C NMR). These were reacted with [ReCl(CO)5] to give the corresponding mononuclear chloro-fac-tricarbonylrhenium(I) [ReCl(CO)3L] compounds. The complexes were characterized by elemental analysis, thermogravimetry (TG) and differential scanning calorimetry (DSC),

Inmaculada Picón-Ferrer; Francisco Hueso-Ureña; Nuria A. Illán-Cabeza; Sonia B. Jiménez-Pulido; José M. Martínez-Martos; María J. Ramírez-Expósito; Miguel N. Moreno-Carretero

2009-01-01

391

Enzyme Reactions  

NSDL National Science Digital Library

The enzyme reaction rate activity allows students to simulate the effects of variables such as temperature and pH on the reaction rate of the enzyme catalase. This computer simulation is best used after the students have done a wet lab experiment. The value of the simulation is that it requires the students to interpret and analyze the graphical representation of data and it enables the running of mutiple experiments in a short amount of time.

School, Maryland V.

392

The Diels-Alder reaction between substituted 6,6-dimethyl-2-vinylnorpinenes and maleic anhydride  

Microsoft Academic Search

Cycloaddition of substituted 6,6-dimethyl-2-vinylnorpinenes with maleic anhydride occursvia the attack of a dienophile on diene from the less hindered side of the bicyclic fragment. IR, UV, CD, and1H NMR spectra of adducts have been studied.

I. A. Nuretdinov; I. P. Karaseva; V. P. Gubskaya; A. V. Il'yasov

1995-01-01

393

3-phenyl-1H-indole-5-sulfonamides: structure-based drug design of a promising class of carbonic anhydrase inhibitors.  

PubMed

A series of 2-(hydrazinocarbonyl)-3-substituted-phenyl-1H-indole-5-sulfonamides possessing various 2-, 3- or 4- substituted phenyl groups with methyl-, halogeno- and methoxy- functionalities, as well as the perfluorophenyl moiety have been synthesized and evaluated as inhibitors of both ?- and ?-class carbonic anhydrases (CAs, EC 4.2.1.1). All human isoforms with medicinal chemistry applications were included in such studies, among which CA I, II, VA, VB, VII, IX and XII. Several low nanomolar, sometimes isoform-selective compounds were thus detected. Two ?-CAs from the pathogenic bacterium Mycobacterium tuberculosis encoded by the genes Rv1284 Rv3588c were also highly inhibited (sometimes in the sub-nanomolar range) by some pyridinium derivatives incoprorating this scaffold, obtained from the corresponding 2-(hydrazinocarbonyl)-3-substituted-phenyl-1H-indole-5-sulfonamides by reaction with pyrylium salts. The fungal ?-CAs from Candida albicans (Nce103) and Cryptococcus neoformans (Can2) were also investigated for their inhibition with this family of sulfonamides and some highly effective inhibitors detected. As the X-ray crystal structure of one such sulfonamide with the human isoform CA II is also know, the 3-substituted-phenyl-1H-indole-5-sulfonamides represent a totally new class of inhibitors obtained by structure-based drug design, which show efficiency in inhibiting both ?- and ?-CAs from several species. PMID:20819062

Güzel, Ozlen; Innocenti, Alessio; Vullo, Daniela; Scozzafava, Andrea; Supuran, Claudiu T

2010-01-01

394

Stereo vision for small targets in IR image sequences  

NASA Astrophysics Data System (ADS)

Surveillance systems against missile attacks require the automatic detection of targets with low false alarm rate (FAR). Infrared Search and Track (IRST) systems offer a passive detection of threats at long ranges. For maximum reaction time and the arrangement of counter measurements, it is necessary to declare the objects as early as possible. For this purpose the detection and tracking algorithms have to deal with point objects. Conventional object features like shape, size and texture are usually unreliable for small objects. More reliable features of point objects are three-dimensional spatial position and velocity. At least two sensors observing the same scene are required for multi-ocular stereo vision. Mainly three steps are relevant for successful stereo image processing. First of all the precise camera calibration (estimating the intrinsic and extrinsic parameters) is necessary to satisfy the demand of high degree of accuracy, especially for long range targets. Secondly the correspondence problem for the detected objects must be solved. Thirdly the three-dimensional location of the potential target has to be determined by projective transformation. For an evaluation a measurement campaign to capture image data was carried out with real targets using two identical IR cameras and additionally synthetic IR image sequences have been generated and processed. In this paper a straightforward solution for stereo analysis based on stationary bin-ocular sensors is presented, the current results are shown suggestions for future work are given.

Jutzi, Boris; Gabler, Richard; Jaeger, Klaus

2001-11-01

395

1H and 2H NMR spectroscopic studies on the metabolism and biochemical effects of 2-bromoethanamine in the rat.  

PubMed

Male Fischer 344 rats were dosed with 2-bromoethanamine hydrobromide (BEA, N = 6) or [1,2,2,-2H4]-bromoethanamine hydrobromide (BEA-d4, N = 6) at 150 mg/kg i.p. and urine was collected -24 to 0 hr pre-dose and at 0-2 hr, 2-4 hr, 4-8 hr and 8-12 hr post-dose (p.d.). Urine samples were analysed directly using 500 and 600 MHz 1H NMR and 92.1 MHz 2H NMR spectroscopy. The major observed effect of BEA treatment was the induction of transient elevations in urinary glutaric acid (GTA) and adipic acid (ADA) excretion lasting up to 24 hr p.d. Most of the GTA was excreted in the 0-8 hr p.d. with maximal rates of 100-120 microM/hr for each rat occurring between 4 and 8 hr p.d. in animals treated with BEA or BEA-d4. GTA and ADA were shown to be of endogenous origin as there was no detectable incorporation of the 2H label into either compound following treatment of rats with BEA-d4. Following BEA-treatment there was an initial decrease in the levels of urinary citrate, succinate, 2-oxoglutarate and trimethylamine-N-oxide. A subsequent recovery of citrate and succinate was noted following the onset of medullary nephropathy. The abnormal urinary metabolite profiles were similar to that observed in the urine of humans with glutaric aciduria type II (an inborn error of metabolism) caused by a lack of mitochondrial fatty acyl coenzyme A dehydrogenases indicating that BEA or its metabolites have similar metabolic consequences. The BEA metabolite aziridine was detected by 1H and 2H NMR spectroscopy of the urine 8 hr p.d. together with BEA itself and two novel metabolites 2-oxazolidone (OX) and 5-hydroxy-2-oxazolidone (HOX). The formation of OX requires the reaction of BEA with endogenous bicarbonate followed by a cyclisation reaction eliminating HBr. Dosing rats with authentic OX resulted in the excretion of HOX but did not cause glutaric or adipic aciduria indicating that either aziridine or BEA itself was responsible for the presumed defect in mitochondrial metabolism. PMID:7763276

Holmes, E; Caddick, S; Lindon, J C; Wilson, I D; Kryvawych, S; Nicholson, J K

1995-05-17

396

Wittig Reaction 33 Reaction: Synthesis of Alkenes  

E-print Network

elimination reactions (E1 or E2 reactions from alcohols or alkyl halides, for example), in eliminationWittig Reaction 33 The Wittig Reaction: Synthesis of Alkenes Intro The "Wittig Reaction" is one reactions the carbon skeleton is already pre-assembled. In the Wittig reaction, however, two smaller carbon

Jasperse, Craig P.

397

Promoting effect of Ir on the catalytic property of Ru/ZnO catalysts for selective hydrogenation of crotonaldehyde  

NASA Astrophysics Data System (ADS)

A series of ZnO supported Ru-Ir bimetal catalysts were prepared and tested for vapor-phase selective hydrogenation of crotonaldehyde. The addition of Ir could effectively promote the catalytic performance, especially the catalyst stability. A Ru-0.5Ir/ZnO catalyst showed the highest activity (a conversion of 63.3%) and selectivity to crotyl alcohol (94.4%) after 30 h reaction. The enhanced stability was attributed to the modified electronic property of Ru by the formation of RuIr alloy as the X-ray photoelectron spectroscopy results showed charge transfer from Ru to Ir, as well as the weakened surface acidity in the Ru-Ir/ZnO catalyst as evidenced by NH3 temperature-programmed desorption technique. Besides, the deactivation of the catalysts was due to the strong chemisorption of CO on the metal surface via decarbonylation reaction and deposition of organic compounds on the catalyst surface, which was characterized by CO poisoning experiment, CO temperature-programmed desorption and temperature-programmed oxidation methods.

Li, Bo; Hong, Xiao; Lin, Jian-Jun; Hu, Geng-Shen; Yu, Qin; Wang, Yue-Juan; Luo, Meng-Fei; Lu, Ji-Qing

2013-09-01

398

NMR resonance splitting of urea in stretched hydrogels: Proton exchange and 1H/2H isotopologues  

NASA Astrophysics Data System (ADS)

Urea at ?12 M in concentrated gelatin gel, that was stretched, gave 1H and 2H NMR spectral splitting patterns that varied in a predictable way with changes in the relative proportions of 1H2O and 2H2O in the medium. This required consideration of the combinatorics of the two amide groups in urea that have a total of four protonation/deuteration sites giving rise to 16 different isotopologues, if all the atoms were separately identifiable. The rate constant that characterized the exchange of the protons with water was estimated by back-transformation analysis of 2D-EXSY spectra. There was no 1H NMR spectral evidence that the chiral gelatin medium had caused in-equivalence in the protons bonded to each amide nitrogen atom. The spectral splitting patterns in 1H and 2H NMR spectra were accounted for by intra-molecular scalar and dipolar interactions, and quadrupolar interactions with the electric field gradients of the gelatin matrix, respectively.

Kuchel, Philip W.; Naumann, Christoph; Chapman, Bogdan E.; Shishmarev, Dmitry; Håkansson, Pär; Bacskay, George; Hush, Noel S.

2014-10-01

399

Quantitative 1H MRI and MRS Microscopy of Individual V79 Lung Tumor Spheroids  

NASA Astrophysics Data System (ADS)

In this Communication 1H MRI and MRS microscopy experiments of individual V79 lung tumor spheroids with diameters between 550 and 650 ?m are reported. The results have been used to determine the T1, T2, and Dvalues as well as the concentrations of water, total choline, creatine/phosphocreatine, and mobile lipids in the viable rims and in the necrotic centers.

Minard, Kevin R.; Guo, Xiuling; Wind, Robert A.

1998-08-01

400

On the measurement of 15N-{ 1H} nuclear Overhauser effects  

NASA Astrophysics Data System (ADS)

Accurate quantification of the 15N-{ 1H} steady-state NOE is central to current methods for the elucidation of protein backbone dynamics on the fast, sub-nanosecond time scale. This experiment is highly susceptible to systematic errors arising from multiple sources. The nature of these errors and their effects on the determined NOE ratio is evaluated by a detailed analysis of the spin dynamics during the pair of experiments used to measure this ratio and possible improvements suggested. The experiment that includes 1H irradiation, is analyzed in the framework of Average Liouvillian Theory and a modified saturation scheme that generates a stable steady-state and eliminates the need to completely saturate 1H nuclei is presented. The largest source of error, however, in 1H-dilute systems at ultra-high fields is found to be an overestimation of the steady-state NOE value as a consequence of the incomplete equilibration of the magnetization in the so-called "reference experiment". The use of very long relaxation delays is usually an effective, but time consuming, solution. Here, we introduce an alternative reference experiment, designed for larger, deuterated systems, that uses the fastest relaxing component of the longitudinal magnetization as a closer approximation to the equilibrium state for shorter relaxation delays. The utility of the modified approach is illustrated through simulations on realistic spin systems over a wide range of time scales and experimentally verified using a perdeuterated sample of human ubiquitin.

Ferrage, Fabien; Piserchio, Andrea; Cowburn, David; Ghose, Ranajeet

2008-06-01

401

THE ROLE OF FIRE IN LAND/WATER INTERACTIONS1/ H. E. Wright, Jr  

E-print Network

methods by which fire frequency can be determined for the time range beyond the tree-ring recordTHE ROLE OF FIRE IN LAND/WATER INTERACTIONS1/ H. E. Wright, Jr · . Regent's Professor of Geology, Ecology, and Botany University of Minnesota ABSTRACT Forest fires cause a temporary increase in runoff

402

Low-E probe for 19 F- 1 H NMR of dilute biological solids  

Microsoft Academic Search

Sample heating induced by radio frequency (RF) irradiation presents a significant challenge to solid state NMR experiments in pro- teins and other biological systems, causing the sample to dehydrate which may result in distorted spectra and a damaged sample. In this work we describe a large volume, low-E 19 F- 1 H solid state NMR probe, which we developed for

Peter L. Gor; Raiker Witter; Eduard Y. Chekmenev; Farhod Nozirov; Riqiang Fu; William W. Brey

2007-01-01

403

Molecular Structures from [superscript 1]H NMR Spectra: Education Aided by Internet Programs  

ERIC Educational Resources Information Center

The article presents the way in which freeware Internet programs can be applied to teach [superscript 1]H NMR spectroscopy. The computer programs described in this article are part of the educational curriculum that explores spectroscopy and spectra interpretation. (Contains 6 figures.)

Debska, Barbara; Guzowska-Swider, Barbara

2007-01-01

404

GPS Time Synchronization System for K2K 1 H. G. Berns and R. J. Wilkes  

E-print Network

GPS Time Synchronization System for K2K 1 H. G. Berns and R. J. Wilkes Department of Physics System (GPS) provides a means for satisfying this requirement at very low cost. In addition to low­resolution time data (day of year, hour, minute, second), commercial GPS receivers output a 1 pulse per sec (1PPS

Berns, Hans-Gerd

405

GPS Time Synchronization System for K2K1 H. G. Berns and R. J. Wilkes  

E-print Network

GPS Time Synchronization System for K2K1 H. G. Berns and R. J. Wilkes Department of Physics System (GPS) provides a means for satisfying this requirement at very low cost. In addition to low- resolution time data (day of year, hour, minute, second), commercial GPS receivers output a 1 pulse per sec

Berns, Hans-Gerd

406

Toward Arabidopsis thaliana hydrophilic metabolome: assessment of extraction methods and quantitative 1H NMR.  

PubMed

Our goal was to establish the hydrophilic metabolome of heterotrophic Arabidopsis thaliana cells grown in suspension, a cellular model of plant sink tissues. Water-soluble metabolites were extracted using four protocols: perchloric acid, boiling ethanol, methanol and methanol/chloroform (M/Chl). They were detected and quantified using (1)H nuclear magnetic resonance (NMR) spectroscopy at 400 MHz. Extraction yields and reproducibility of the extraction methods were investigated. The effects of cell harvest protocol, cell grinding and lyophilization and storage conditions on the measured metabolic profiles were also studied. These quantitative studies demonstrated for the first time that the four extraction protocols commonly used do lead to quite similar molecular compositions as analyzed by (1)H NMR. The M/Chl method proved effective and reliable to prepare series of physiologically significant extracts from plant cells for (1)H NMR analysis. Reproducibility of the detected metabolome was assessed over long periods of time by analyzing a large number of separate extracts prepared from independent cultures. Larger variations in the NMR metabolite profiles could be correlated to changes in physiological parameters of the culture medium. Quantitative resolved (1)H NMR of cell extracts proved to be robust and reliable for routine metabolite profiling of plant cell cultures. PMID:20522173

Gromova, Marina; Roby, Claude

2010-10-01

407

Synthesis of stereospecifically deuterated desoxypodophyllotoxins and 1H-nmr assignment of desoxypodophyllotoxin  

NASA Technical Reports Server (NTRS)

[4 beta- 2H1]Desoxypodophyllotoxin [3], [4 alpha- 2H1]desoxypodophyllotoxin [4], and [4, 4- 2 H2]desoxypodophyllotoxin [9] were prepared from podophyllotoxin [1] via its chloride [5]. A complete assignment of the 1H-nmr spectrum of desoxypodophyllotoxin [2] was made on the basis of the spectra of the deuterated compounds [3] and [4].

Pullockaran, A. J.; Kingston, D. G.; Lewis, N. G.

1989-01-01

408

CALCIUM TRANSLOCATION IN THE AVIAN SHELL GLAND (1) H. SCHRAER Rosemary SCHRAER  

E-print Network

. It is possible that in the high producers the calcium reserves were depleted due to the demands of calciumCALCIUM TRANSLOCATION IN THE AVIAN SHELL GLAND (1) H. SCHRAER Rosemary SCHRAER Department because of the large changes in calcium metabolism that occurred during the reproductive cycle

Boyer, Edmond

409

Investigation of oxidative status of the 2-furan-2-yl-1H-benzimidazole in rats.  

PubMed

We investigated the influence of 2-furan-2-yl-1H-benzimidazole regarding vitamins A, E, C, selenium (Se), malondialdehyde (MDA), and glutathione peroxidase (GSH-Px) levels on rats. 2-Furan-2-yl-1H-benzimidazole was given to rats by subcutaneous injection every other day for a total of 22 injections. At the end of the experiment, Se levels were determined by using a fluorimetric method. Serum levels of vitamins A, E, C, and malondialdehyde (MDA) were determined by high-performance liquid chromatography. Glutathione peroxidase (GSH-Px) levels of erythrocytes were spectrophotometrically determined. Our experimental results showed that vitamins A, E, C, and Se levels were found generally lower than the control groups, while serum MDA level and GSH-Px activity flexibly increased, which is dependent on injection days. The observed decreases in vitamins A, E, C, and Se levels in the blood might be causally related to the increased amount of free radicals that are generated with 2-furan-2-yl-1H-benzimidazole injection. However, further investigations are needed to clarify the significance of this observation in respect with the 2-furan-2-yl-1H-benzimidazole injection. PMID:18781285

Karatas, Fikret; Servi, Suleyman; Kara, Haki; Kiran, Tuba R; Saydam, Sinan

2008-01-01

410

1H, 15N and 13C NMR Assignments of Mouse Methionine Sulfoxide Reductase B2  

PubMed Central

A recombinant mouse methionine-r-sulfoxide reductase 2 (MsrB2?S) isotopically labeled with 15N and 15N/13C was generated. We report here the 1H, 15N and 13C NMR assignments of the reduced form of this protein. PMID:19636904

Breivik, Ashild S.; Aachmann, Finn L.; Sal, Lena S.; Kim, Hwa-Young; Del Conte, Rebecca; Gladyshev, Vadim N.; Dikiy, Alexander

2011-01-01

411

Selective reduction and functionalization of diethyl 1-alkyl-1 H-indole-2,3-dicarboxylates  

Microsoft Academic Search

A convenient and highly selective reduction of easily accessible indole-2,3-dicarboxylates is described. Ten different 1-alkyl-2-formyl-1H-indole-3-carboxylates are obtained in high yield and represent interesting building blocks for novel indoles.

Iliyas Ali Sayyed; Karolin Alex; Annegret Tillack; Nicolle Schwarz; Anke Spannenberg; Dirk Michalik; Matthias Beller

2008-01-01

412

Bulk magnetization and 1H NMR spectra of magnetically heterogeneous model systems  

SciTech Connect

Bulk magnetization and {sup 1}H static and magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectra of two magnetically heterogeneous model systems based on laponite (LAP) layered silicate or polystyrene (PS) with low and high proton concentration, respectively, and ferrimagnetic Fe{sub 2}O{sub 3} nano- or micro-particles have been studied. In LAP+Fe{sub 2}O{sub 3}, a major contribution to the NMR signal broadening is due to the dipolar coupling between the magnetic moments of protons and magnetic particles. In PS+Fe{sub 2}O{sub 3}, due to the higher proton concentration in polystyrene and stronger proton–proton dipolar coupling, an additional broadening is observed, i.e. {sup 1}H MAS NMR spectra of magnetically heterogeneous systems are sensitive to both proton–magnetic particles and proton–proton dipolar couplings. An increase of the volume magnetization by ?1 emu/cm{sup 3} affects the {sup 1}H NMR signal width in a way that is similar to an increase of the proton concentration by ?2×10{sup 22}/cm{sup 3}. {sup 1}H MAS NMR spectra, along with bulk magnetization measurements, allow the accurate determination of the hydrogen concentration in magnetically heterogeneous systems.

Levin, E. M.; Bud& #x27; ko, S. L.

2011-04-28

413

Bulk magnetization and 1H NMR spectra of magnetically heterogeneous model systems  

NASA Astrophysics Data System (ADS)

Bulk magnetization and 1H static and magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectra of two magnetically heterogeneous model systems based on laponite (LAP) layered silicate or polystyrene (PS) with low and high proton concentration, respectively, and ferrimagnetic Fe2O3 nano- or micro-particles have been studied. In LAP+Fe2O3, a major contribution to the NMR signal broadening is due to the dipolar coupling between the magnetic moments of protons and magnetic particles. In PS+Fe2O3, due to the higher proton concentration in polystyrene and stronger proton-proton dipolar coupling, an additional broadening is observed, i.e. 1H MAS NMR spectra of magnetically heterogeneous systems are sensitive to both proton-magnetic particles and proton-proton dipolar couplings. An increase of the volume magnetization by ?1 emu/cm3 affects the 1H NMR signal width in a way that is similar to an increase of the proton concentration by ?2×1022/cm3. 1H MAS NMR spectra, along with bulk magnetization measurements, allow the accurate determination of the hydrogen concentration in magnetically heterogeneous systems.

Levin, E. M.; Bud'ko, S. L.

2011-10-01

414

Determination of protoberberine alkaloids in Rhizoma Coptidis by ERETIC 1H NMR method  

Microsoft Academic Search

An alternative quantification approach called ERETIC (Electronic REference To access In vivo Concentrations) utilizing electronic reference-based proton nuclear magnetic resonance (1H NMR) spectroscopy techniques has been successfully introduced in our present study to simultaneously determine the contents of five major active protoberberine alkaloids (berberine, coptisine, jatrorrhizine, palmatine and epiberberine) in Rhizoma Coptidis, one of the most commonly used traditional Chinese

Pei-Lan Ding; Li-Qin Chen; Yang Lu; Yong-Guo Li

415

Cross Sections of Proton Induced Nuclear Reactions on Iridium  

SciTech Connect

Excitation functions of the reactions natIr(p,xn)188,189,191Pt and natIr(p,x)186,187,188,189,190,192Ir were measured up to 70 MeV for practical applications. The measured experimental data were compared with the earlier results and analyzed using theoretical calculations based on the model code Alice-IPPE, The new experimental data show significant deviations from the earlier experimental results. Good agreement was found on average with the model calculation. Applications are also discussed.

Tarkanyi, F.; Ditroi, F.; Takacs, S.; Kiraly, B. [Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), 4026 Debrecen (Hungary); Hermanne, A. [Cyclotron Laboratory, Vrije Universiteit Brussel, 1090 Brussels (Belgium); Uddin, M.S.; Hagiwara, M.; Baba, M. [Cyclotron and Radioisotope Center, Tohoku University, Sendai 980-8578 (Japan); Shubin, Yu.N.; Dityuk, A.I. [Institute of Physics and Power Engineering, Obninsk 249020 (Russian Federation)

2005-05-24

416

IR spectra of flavins in solution: DFT/MM description of redox effects.  

PubMed

The functional reactions in blue light photoreceptors generally involve transiently reduced flavins exhibiting characteristic infrared (IR) spectra. To approach a theoretical understanding, here we apply density functional theory (DFT) to flavin radicals embedded in a molecular mechanics (MM) model of an aqueous solution. Combining a DFT/MM approach with instantaneous normal-mode analyses (INMA), we compute the IR solution spectra of anionic and neutral flavin radicals. For a set of mid-IR marker bands, we identify those changes of spectral locations, intensities, and widths, which are caused by sequentially adding an electron and a proton to the oxidized flavin. Comparisons with experimental IR solution spectra of flavin radicals show the accuracy of our DFT/MM-INMA approach and allow us to assign the observed bands. The room temperature ensembles of solvent cages required for the INMA calculations of the IR spectra are generated in an MM setting from molecular dynamics (MD) simulations. For the solvated flavin radicals, these MD simulations employ MM force fields derived from DFT/MM calculations. PMID:21309580

Rieff, Benjamin; Bauer, Sebastian; Mathias, Gerald; Tavan, Paul

2011-03-10

417

Temperature Dependence of Blue Phosphorescent Cyclometalated Ir(III) Complexes  

E-print Network

Temperature Dependence of Blue Phosphorescent Cyclometalated Ir(III) Complexes Tissa Sajoto, Peter) cyclometalated Ir(III) complexes (fac- Ir(C N)3 (C N ) 2-phenylpyridyl (ppy), 2-(4,6-difluorophenyl)pyridyl (F2-(2-(9,9-dimethylfluorenyl))pyrazolyl (flz)), fac-Ir(C N)2(C N) (C N ) ppz or F2ppz and C N ) ppy or F2ppy), and fac-Ir(C C)3

Goddard III, William A.

418

The synthesis and characterization of nonperipherally tetra terminal alkynyl substituted phthalocyanines and glycoconjugation via the click reaction.  

PubMed

In order to obtain nonperipherally tetra terminal alkynyl substituted phthalocyanines (Pcs), new 3-pent-4-ynyloxy phthalonitrile (3) was prepared by the nucleophilic displacement reaction of 3-nitrophthalonitrile (1) and 4-pentyn-1-ol (2) and then cyclotetramerization was attained in the presence of zinc acetate, cobalt acetate, and/or DBU in n-pentanol without protection/deprotection. For the first time, the glycoconjugation of the nonperipherally tetra terminal alkynyl substituted zinc phthalocyanine (ZnPc) (6) can be easily achieved via the click reaction in a high yield. The electronic absorption spectrum of the glucopyranosyl substituted ZnPc (10) derivative showed a red-shifted Q band at 751 nm in dichloromethane due to the protonation of the meso nitrogens of the Pc macrocycle. Deacylation yielded ZnPc (11) bearing glucose substituents at nonperipheral positions with an improved water-solubility and non-aggregation in DMSO. The chemical structures of the new compounds were characterized by (1)H NMR, (13)C NMR, FT-IR, UV-Vis, mass spectrometry and elemental analysis. Moreover, the phthalonitrile compound was characterized using X-ray. PMID:24763524

Kanat, Zeliha; Dinçer, Hatice

2014-06-21

419

Effect of vaccination of cattle with the low virulence Nc-Spain 1H isolate of Neospora caninum against a heterologous challenge in early and mid-gestation.  

PubMed

Live vaccines have emerged as one of the most potentially cost-effective measures for the control of bovine neosporosis. Previous studies have shown that Nc-Spain 1H is a naturally attenuated isolate of Neospora caninum and that immunisation with live Nc-Spain 1H tachyzoites generated a protective immune response in mice. The aim of this study was to evaluate the safety and efficacy of immunisation in cattle. N. caninum-seronegative heifers were immunised subcutaneously twice with 107 live Nc-Spain 1H tachyzoites prior to artificial insemination. No adverse reactions or negative effects on reproductive parameters were recorded following immunisation. In immunised and non-challenged heifers, no foetal deaths were observed, and none of the calves was congenitally infected. The efficacy against N. caninum-associated foetal death and vertical transmission was determined after challenge with high doses of the Nc-1 isolate at 70 and 135 days of gestation, respectively. After the challenge in early gestation, the immunisation induced a protection of 50% against foetal death. In addition, the microsatellite analysis performed in PCR-positive tissue samples from foetuses that died after challenge infection showed that the profiles corresponded to the challenge isolate Nc-1. A degree of protection against vertical transmission was observed after challenge at mid-gestation; calves from immunised heifers showed significantly lower pre-colostral Neospora-specific antibody titres than calves from the non-immunised/challenge group (P < 0.05). Strong antibody and interferon gamma responses were induced in the immunised heifers. This study indicates that the immunisation before pregnancy with the Nc-Spain 1H vaccine isolate appeared to be safe and reduced the occurrence of N. caninum-associated abortion and vertical transmission in experimentally infected cattle. In light of these encouraging results, the next step for testing this live attenuated candidate should be the assessment of its efficacy and safety in naturally infected cattle. PMID:24180373

Rojo-Montejo, Silvia; Collantes-Fernández, Esther; Pérez-Zaballos, Francisco; Rodríguez-Marcos, Sonia; Blanco-Murcia, Javier; Rodríguez-Bertos, Antonio; Prenafeta, Antoni; Ortega-Mora, Luis Miguel

2013-01-01

420

Statistical total correlation spectroscopy editing of 1H NMR spectra of biofluids: application to drug metabolite profile identification and enhanced information recovery.  

PubMed

Here we present a novel method for enhanced NMR spectral information recovery, utilizing a statistical total correlation spectroscopy editing (STOCSY-E) procedure for the identification of drug metabolite peaks in biofluids and for deconvolution of drug and endogenous metabolite signals. Structurally correlated peaks from drug metabolites and those from closely related drug metabolite pathways are first identified using STOCSY. Subsequently, this correlation information is utilized to scale the biofluid (1)H NMR spectra across these identified regions, producing a modified set of spectra in which drug metabolite contributions are reduced and, thus, facilitating analysis by pattern recognition methods without drug metabolite interferences. The application of STOCSY-E is illustrated with two exemplar (1)H NMR spectroscopic data sets, posing various drug metabolic, toxicological, and analytical challenges viz. 800 MHz (1)H spectra of human urine (n = 21) collected over 10 h following dosing with the antibiotic flucloxacillin and 600 MHz (1)H NMR spectra of rat urine (n = 27) collected over 48 h following exposure to the renal papillary toxin 2-bromoethanamine (BEA). STOCSY-E efficiently identified and removed the major xenobiotic metabolite peaks in both data sets, providing enhanced visualization of endogenous changes via orthogonal to projection filtered partial least-squares discriminant analysis (OPLS-DA). OPLS-DA of the STOCSY-E spectral data from the BEA-treated rats revealed the gut bacterial-mammalian co-metabolite phenylacetylglycine as a previously unidentified surrogate biomarker of toxicity. STOCSY-E has a wide range of potential applications in clinical, epidemiology, toxicology, and nutritional studies where multiple xenobiotic metabolic interferences may confound biological interpretation. Additionally, this tool could prove useful for applications outside of metabolic analysis, for example, in process chemistry for following chemical reactions and equilibria and detecting impurities. PMID:19580292

Sands, Caroline J; Coen, Muireann; Maher, Anthony D; Ebbels, Timothy M D; Holmes, Elaine; Lindon, John C; Nicholson, Jeremy K

2009-08-01

421

Effect of vaccination of cattle with the low virulence Nc-Spain 1H isolate of Neospora caninum against a heterologous challenge in early and mid-gestation  

PubMed Central

Live vaccines have emerged as one of the most potentially cost-effective measures for the control of bovine neosporosis. Previous studies have shown that Nc-Spain 1H is a naturally attenuated isolate of Neospora caninum and that immunisation with live Nc-Spain 1H tachyzoites generated a protective immune response in mice. The aim of this study was to evaluate the safety and efficacy of immunisation in cattle. N. caninum-seronegative heifers were immunised subcutaneously twice with 107 live Nc-Spain 1H tachyzoites prior to artificial insemination. No adverse reactions or negative effects on reproductive parameters were recorded following immunisation. In immunised and non-challenged heifers, no foetal deaths were observed, and none of the calves was congenitally infected. The efficacy against N. caninum-associated foetal death and vertical transmission was determined after challenge with high doses of the Nc-1 isolate at 70 and 135 days of gestation, respectively. After the challenge in early gestation, the immunisation induced a protection of 50% against foetal death. In addition, the microsatellite analysis performed in PCR-positive tissue samples from foetuses that died after challenge infection showed that the profiles corresponded to the challenge isolate Nc-1. A degree of protection against vertical transmission was observed after challenge at mid-gestation; calves from immunised heifers showed significantly lower pre-colostral Neospora-specific antibody titres than calves from the non-immunised/challenge group (P?1H vaccine isolate appeared to be safe and reduced the occurrence of N. caninum-associated abortion and vertical transmission in experimentally infected cattle. In light of these encouraging results, the next step for testing this live attenuated candidate should be the assessment of its efficacy and safety in naturally infected cattle. PMID:24180373

2013-01-01

422

Accelerator production of 122Xe(20.1 h) as a source of 122I(3.6 m) labeled radiopharmaceuticals for applications in positron emission tomography  

NASA Astrophysics Data System (ADS)

Iodine-122 (3.6 m) radiopharmaceuticals have a proven potential for accelerator-free PET studies, including brain and heart perfusion, using a 122Xe?122I transportable generator. Nuclear reactions with up to 70 MeV proton beams were studied to produce the parent 122Xe(20.1 h) radionuclide. Theoretical and experimental measurements indicated that 122Xe can be produced in high yields allowing for an extensive use of a 122Xe?122I generator capable of producing multiple doses of 122I radiopharmaceuticals. Other lower energy reactions were studied and the results indicated the possibility of developing new methods that could be available to a larger number of commercial and research accelerators operating worldwide.

Lagunas-Solar, M. C.; Zeng, N. X.; Castaneda, C. M.; Carvacho, O. F.; VanBrocklin, H. F.; O'Neil, J. P.; Padgett, H. C.; Budinger, T. F.

1999-06-01

423

Taxol reactions.  

PubMed

Paclitaxel (Taxol) a taxane antineoplastic agent causing irreversible microtubule aggregation with activity against breast, ovarian, lung, head and neck, bladder, testicular, esophageal, endometrial and other less common tumors was derived from the bark of the Pacific yew (Taxus brevifolia). Phase I trials conducted in the late 1980s were almost halted because of the high frequency of hypersensitivity-like reactions. Respiratory distress (dyspnea and/or bronchospasm), hypotension, and angioedema were the major manifestations, but flushing, urticaria, chest, abdomen, and extremity pains were described also. Reactions occurred on first exposure in the majority of cases raising etiologic questions. The vehicle for paclitaxel Cremophor EL (polyoxyethylated castor oil in 50% ethanol) was strongly suspect as a direct (non-immunoglobulin E dependent) histamine releaser. Premedication regimens and longer infusion times lowered the incidence of reactivity allowing phase II and III trials to progress through the early 1990s. The mechanism(s) underlying paclitaxel hypersensitivity-like reactions is still unknown, and clinical data on probable complement and mast cell activation are lacking. The original clinical trial protocols for paclitaxel required discontinuation of therapy for patients who experienced hypersensitivity-like reactions. Here, we review the current etiologic knowledge of these reactions and describe our clinical approach to allow completion of chemotherapy with this powerful plant-derived agent. PMID:12125509

Price, Kursteen S; Castells, Mariana C

2002-01-01

424

The TAC IR FEL Oscillator Facility Project  

E-print Network

The TAC (Turkish Accelerator Center) IR FEL Oscillator facility, which has been supported by Turkish State Planning Organization (SPO) since 2006, will be based on a 15-40 MeV electron linac accompanying two different undulators with 2.5 cm and 9 cm periods in order to obtain IR FEL ranging between 2-250 microns. The electron linac will consist of two sequenced modules, each housing two 9-cell superconducting TESLA cavities for cw operation. It is planned that the TAC IR FEL facility will be completed in 2012 at Golbasi campus of Ankara University. This facility will give an opportunity to the scientists and industry to use FEL in research and development in Turkey and our region. In this study, the results of optimization studies and present plans about construction process of the facility are presented.

Ketenoglu, B; Yavas, O; Tural, M; Karsli, O; Ozkorucuklu, S; Arikan, P; Kasap, E; Yildiz, H; Bilen, B; Aksakal, H; Tapan, I

2009-01-01

425

IR signature management for the modern navy  

NASA Astrophysics Data System (ADS)

A methodology for analysing the infrared (IR) signature and susceptibility of naval platforms using ShipIR/NTCS was presented by Vaitekunas (2010). This paper provides three key improvements: use of a larger climatic data set (N=100), a new target sub-image algorithm eliminating false detections from pixel-aliasing at the horizon, and a new seeker model interfacing with a line-by-line background clutter model. Existing commercial stealth technologies (exhaust stack suppression, low solar absorptive paints, extended hull film-cooling) are re-analysed using the new models and methods to produce a more rigorous and comprehensive analysis of their effectiveness based on the statistics of reduction in IR susceptibility. These methods and results combined with the cost of each stealth option should allow platform managers to select an appropriate level of infrared suppression and establish the design criteria for a new ship.

Vaitekunas, David A.; Kim, Yoonsik

2013-06-01

426

Buckled silicene formation on Ir(111).  

PubMed

Silicene, a two-dimensional (2D) honeycomb structure similar to graphene, has been successfully fabricated on an Ir(111) substrate. It is characterized as a (?7×?7) superstructure with respect to the substrate lattice, as revealed by low energy electron diffraction and scanning tunneling microscopy. Such a superstructure coincides with the (?3×?3) superlattice of silicene. First-principles calculations confirm that this is a (?3×?3)silicene/(?7×?7)Ir(111) configuration and that it has a buckled conformation. Importantly, the calculated electron localization function shows that the silicon adlayer on the Ir(111) substrate has 2D continuity. This work provides a method to fabricate high-quality silicene and an explanation for the formation of the buckled silicene sheet. PMID:23330602

Meng, Lei; Wang, Yeliang; Zhang, Lizhi; Du, Shixuan; Wu, Rongting; Li, Linfei; Zhang, Yi; Li, Geng; Zhou, Haitao; Hofer, Werner A; Gao, Hong-Jun

2013-02-13

427

MTR and In-vivo 1H-MRS studies on mouse brain with parkinson's disease  

NASA Astrophysics Data System (ADS)

The aim of this study was to investigate whether the changes in the magnetization transfer ratio (MTR) histogram are related to specific characteristics of Parkinson's disease (PD) and to investigate whether the MTR histogram parameters are associated with neurochemical dysfunction by performing in vivo proton magnetic resonance spectroscopy (1H-MRS). MTR and in vivo 1H-MRS studies were performed on control mice (n = 10) and 1-methyl-1,2,3,6-tetrahydropyridine intoxicated mice (n = 10). All the MTR and in vivo 1H-MRS experiments were performed on a 9.4 T MRI/MRS system (Bruker Biospin, Germany) using a standard head coil. The protondensity fast spin echo (FSE) images and the T2-weighted spin echo (SE) images were acquired with no gap. Outer volume suppression (OVS), combined with the ultra-short echo-time stimulated echo acquisition mode (STEAM), was used for the localized in-vivo 1H-MRS. The quantitative analysis of metabolites was performed from the 1H spectra obtained in vivo on the striatum (ST) by using jMRUI (Lyon, France). The peak height of the MTR histograms in the PD model group was significantly lower than that in the control group (p < 0.05). The midbrain MTR values for volume were lower in the PD group than the control group(p < 0.05). The complex peak (Glx: glutamine+glutamate+ GABA)/creatine (Cr) ratio of the right ST in the PD group was significantly increased as compared to that of the control group. The present study revealed that the peak height of the MTR histogram was significantly decreased in the ST and substantia nigra, and a significant increase in the Gl x /Cr ratio was found in the ST of the PD group, as compared with that of the control group. These findings could reflect the early phase of neuronal dysfunction of neurotransmitters.

Yoon, Moon-Hyun; Kim, Hyeon-Jin; Chung, Jin-Yeung; Doo, Ah-Reum; Park, Hi-Joon; Kim, Seung-Nam; Choe, Bo-Young

2012-12-01

428

Aqua-bis(2,2?-bipyridine-?2 N,N?)(1H-indole-2-carboxyl-ato-?O)nickel(II) 1H-indole-2-carboxyl-ate dihydrate  

PubMed Central

The hydro­thermal reaction of Ni2(OH)2CO3 with 2,2?-bipyridine and 2-indolyl-formic acid in CH3OH/H2O at 423?K for 7?d produced the novel NiII complex [Ni(C9H6NO2)(C10H8N2)2(H2O)](C9H6NO2)·2H2O. The asymmetric unit of the title compound consists of a monovalent [Ni(L)(bpy)2(H2O)]+ cation (bpy is 2,2?-bipyridine and L is 1H-indole-2-carboxyl­ate), an L anion and two solvent water mol­ecules. In the [Ni(L)(bpy)2(H2O)]+ cations, the Ni atom coordinates to four N atoms from the two bpy ligands and two O atoms, one from a L anion and the other from a water mol­ecule to complete an significantly distorted NiN4O2 octa­hedron. The coordinated and solvate water mol­ecules form an extensive series of O—H?O hydrogen bonds. N—H?O and C—H?O hydrogen bonds are also present and the mol­ecules are inter­linked, forming a three-dimensional network. PMID:21581519

Zhang, Bi-Song; Liu, Zhen-Xiang; Liu, Li-Hua; Pan, Tao; Ye, Su-Fang

2009-01-01

429

Recent progress on mid-IR sensing with optical fibers  

NASA Astrophysics Data System (ADS)

Chemical sensors are analytical systems for the evaluation of compound- or ion-specific or - selective signals produced by specific or selective chemical reactions taking place at the interface between the chemically modified sensor surface and the substrate. The well known electrochemical sensing schemes have greatly contributed that sensors are considered now as the 'third supporting pillar of analytical chemistry' besides chromatography and spectroscopy. The aim of this paper is to describe the novel capabilities of chemical modified IR-transparent fibers as chemical IR-sensors for the on-line analysis of chlorinated hydrocarbons and organic compounds in aqueous solutions and gaseous mixtures, glucose, and sucrose in aqueous solution as developed in our laboratory. Moreover, the relative merits of this new method wil be depicted in comparison to other sensing techniques. Optical fiber sensors are novel analysis systems, based on molecular spectroscopy in the UV/VIS/IR-range. They benefit from the tremendous development in the field of optical fibers, an offspring of the telecommunication industry and the electronic revolution during the last few years. With the development of new materials besides the well known quartz fibers for the UV/VIS/NIR-range the optical window for fiber optic sensors was enlarged from 0,2 to 20 micrometers recently. The fiber length was increased recently to up to 2 meters for silver halides and approximately 10 meters for chalcogenides. New applications for environmental, food, and clinical sensing as well as process analysis are the driving force for modern research in IR-optical fiber sensors using mainly sapphire (Al2O3), chalcogenide (As-Se-Te) and silver halide (AgBr/AgCl) fibers and flow injection analysis (FIA) systems. Few representative examples for each of the various optical sensor types will be presented. Particular attention will be given to the use of silver halide fibers for the simultaneous determination of traces of chlorinated hydrocarbons in water and to FIA-systems for the process analysis of beverages.

Kellner, Robert A.; Gobel, R.; Goetz, R.; Lendl, B.; Edl-Mizaikoff, B.; Tacke, Maurus; Katzir, Abraham

1995-09-01

430

Properties of the {pi}h{sub 11/2} band in the stable nucleus {sup 193}Ir  

SciTech Connect

Excited states in the stable nucleus {sup 193}Ir have been investigated through an in-beam {gamma}-ray spectroscopic technique following the {sup 192}Os({sup 7}Li, {alpha}2n) reaction at a beam energy of 44 MeV. A level scheme built on the {pi}h{sub 11/2} isomer has been extended to high-spin states using eleven newly observed {gamma} transitions. The {pi}h{sub 11/2} band is proposed to be formed by coupling an h{sub 11/2} proton to a core with large triaxial deformation. Three-quasiparticle states are suggested in {sup 193}Ir on referring to the similar states in {sup 187}Ir. The features of signature splitting in the {pi}h{sub 11/2} bands of {sup 187-193}Ir are discussed with the help of total Routhian surface calculations.

Fang, Y. D.; Zhang, Y. H.; Zhou, X. H.; Liu, M. L.; Wang, J. G.; Ma, F.; Guo, Y. X.; Fang, F. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Shi, Y.; Xu, F. R. [Department of Technical Physics and MOE Key Laboratory, Peking University, Beijing 100871 (China); Gao, B. S.; Wang, S. C.; Li, S. C.; Yan, X. L.; He, L.; Wang, Z. G. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Graduate University of Chinese Academy of Sciences, Beijing 000049 (China); Wu, X. G.; He, C. Y.; Zheng, Y.; Wang, Z. M. [China Institute of Atomic Energy, Beijing 102413 (China)

2011-05-15

431

On IR solutions in Horava gravity theories  

E-print Network

In this note we search for large distance solutions of Horava gravity. In the case of the "detailed balance" action, gravity solutions asymptote to IR only above the cosmological constant ($\\sim$horizon) scale. However, if one adds IR dominant terms $\\alpha R^{(3)}+\\beta \\Lambda_W$, one can recover general relativity solutions on usual scales in the real Universe, provided one fine-tunes the cosmological constant, reobtaining the usual cosmological constant problem. We comment on pp wave solutions, in order to gain insight into the relativistic properties of the theory.

Horatiu Nastase

2009-04-23

432

Automatic NMR-based identification of chemical reaction types in mixtures of co-occurring reactions.  

PubMed

The combination of chemoinformatics approaches with NMR techniques and the increasing availability of data allow the resolution of problems far beyond the original application of NMR in structure elucidation/verification. The diversity of applications can range from process monitoring, metabolic profiling, authentication of products, to quality control. An application related to the automatic analysis of complex mixtures concerns mixtures of chemical reactions. We encoded mixtures of chemical reactions with the difference between the (1)H NMR spectra of the products and the reactants. All the signals arising from all the reactants of the co-occurring reactions were taken together (a simulated spectrum of the mixture of reactants) and the same was done for products. The difference spectrum is taken as the representation of the mixture of chemical reactions. A data set of 181 chemical reactions was used, each reaction manually assigned to one of 6 types. From this dataset, we simulated mixtures where two reactions of different types would occur simultaneously. Automatic learning methods were trained to classify the reactions occurring in a mixture from the (1)H NMR-based descriptor of the mixture. Unsupervised learning methods (self-organizing maps) produced a reasonable clustering of the mixtures by reaction type, and allowed the correct classification of 80% and 63% of the mixtures in two independent test sets of different similarity to the training set. With random forests (RF), the percentage of correct classifications was increased to 99% and 80% for the same test sets. The RF probability associated to the predictions yielded a robust indication of their reliability. This study demonstrates the possibility of applying machine learning methods to automatically identify types of co-occurring chemical reactions from NMR data. Using no explicit structural information about the reactions participants, reaction elucidation is performed without structure elucidation of the molecules in the mixtures. PMID:24551112

Latino, Diogo A R S; Aires-de-Sousa, João

2014-01-01

433

PIR fiber sensing in 4- to 18-mum range for flexible IR imaging and process IR spectroscopy  

Microsoft Academic Search

Innovative Polycrystalline IR-fibers (PIR-) from Silver Halide open a variety of promising fiber applications in 4-18 mum range. PIR-fibers coupled with IR-detectors enable unique flexible 2D & 3D IR-imaging, including IR-endoscopy with PIR-fiber bundles. FTIR- and other IR-spectrometers with PIR-fiber probes may be used for remote process molecular control, for in-vivo diagnostics of tissue and for pollution monitoring in liquid

Viatcheslav Artiouchenko; Vladimir A. Lobachev; Mikhail Nikitin; Tatjana Sakharova; Viatcheslav Sakharov; Cezar Wojciechowski

2004-01-01

434

A flexible Au-Ir cell with quick assembly for hydrothermal experiments  

USGS Publications Warehouse

The paper describes a new flexible reaction cell for high-temperature and high-pressure experiments in hydrothermal apparatus. The interior of the cell is all Au, except for two inert Ir gaskets. The design features an all Au cap that can be easily and rapidly assembled and disassembled. The capacity of the cell is approximately 240 mL, with a height of 20 cm and an o.d. of 6 cm. -Authors

Rosenbauer, R. J.; Bischoff, J. L.; Potter, J. M.

1993-01-01

435

Feeding of the 11/2{sup -} isomers in stable Ir and Au isotopes  

SciTech Connect

Excited states in {sup 191}Ir, {sup 193}Ir, and {sup 197}Au were studied and absolute partial {gamma}-ray cross sections were measured using the (n,n{sup '}{gamma}) reaction. A Compton-suppressed germanium-detector array (GEANIE) for {gamma}-ray spectroscopy was used for the measurement and the broad-spectrum pulsed neutron source of the Los Alamos Neutron Science Center's WNR facility provided energetic neutrons. The energy of the incident neutrons was determined using the time-of-flight technique. Absolute partial {gamma}-ray cross sections were measured up to incident neutron energy of 20 MeV for several transitions feeding directly the 11/2{sup -} isomers and ground states in {sup 191}Ir, {sup 193}Ir, and {sup 197}Au. The feeding of the 11/2{sup -} isomers, which originate from the odd proton occupying the h{sub 11/2} orbital, was found for the three targets to be very similar and increasing relative to the feeding of the corresponding ground state with increasing neutron energy up to E{sub n}{approx}10 MeV. Above this neutron energy the opening of the (n,2n) reaction channel strongly affects the population of the isomers and leads to a decrease of their relative population compared to the population of the ground states. The experimental results are compared with theoretical predictions from the GNASH reaction model calculation implementing a version of the spin distribution for the pre-equilibrium reaction piece with either a compound nucleus spin distribution (CN-GNASH) or a Feshbach-Kerman-Koonin (FKK-GNASH) quantum mechanical spin distribution. The effects of the spin cutoff parameter values on the population of states are examined. Evidence is presented that FKK-GNASH provides a description of the experimental data that mitigates the need for adjustment of the level density parameter to fit the data.

Fotiades, N.; Nelson, R. O.; Devlin, M.; Holloway, S.; Kawano, T.; Talou, P.; Chadwick, M. B.; Becker, J. A.; Garrett, P. E. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

2009-10-15

436

Platinum Monolayer Electrocatalysts for O2 Reduction: Pt Monolayer on Carbon-Supported PdIr Nanoparticles  

SciTech Connect

The kinetics of oxygen reduction was investigated in acid solutions on Pt monolayers deposited on modified carbon-supported PdIr nanoparticles using the rotating disk-electrode technique. Iridium is introduced into the Pd substrate in order to fine-tune the Pt-Pd interactions and to improve Pd stability under operating conditions of the fuel cell. The kinetics of the oxygen reduction reaction shows enhancement with the Pt monolayer on the PdIr nanoparticle surfaces in comparison with the reaction on Pt/C and Pt monolayer on Pd/C nanoparticles. The electrochemical measurements suggest that reduced oxidation of Pt monolayer on PdIr/C compared to Pt/C and Pt monolayer on Pd/C is the cause of enhanced activity. Besides a ligand effect induced to the Pt surface by the presence of PdIr in the second sublayer of the nanoparticle, as suggested by our density functional theory analysis, Ir also leads to a Pd skin contraction, so the Pt monolayer on PdIr/C is compressed more than on Pd/C. Both effects lead to further weakening of the Pt-OH interaction, thus increasing the ORR activity. The Pt-specific activity for Pt{sub ML}PdIr/C is three times and 25% higher than that of Pt/C and Pt{sub ML}Pd/C respectively; the Pt-mass activity of Pt{sub ML}PdIr/C is more than 20 times and 25% higher than that of Pt/C and Pt{sub ML}Pd/C, respectively.

Vukmirovic, M.B.; Knupp, S.L. Haldar, P.; Herron, J.A.: Mavrikakis, M.; Adzic, R.R.

2010-11-01

437

Spectrophotometric determination of mimosine and 3-hydroxy-4-(1H)-pyridone--the toxic principles of Leucaena leucocephala.  

PubMed

A sensitive and selective spectrophotometric method for the estimation of the toxic factors mimosine and 3-hydroxy-4-(1H)-pyridone (DHP) has been developed based on the intense yellow-colored azodye formed with p-nitroaniline which showed a sharp absorption maximum at 400 nm. The method was optimized based on relative sensitivity of the reaction with various aromatic primary amino compounds and under different conditions of pH. Interference from a variety of structurally related compounds and phenols was tested and found insensitive to this method. The molar extinction coefficient at 400 nm for the azodye formed with mimosine was 5.31 x 10(4) M-1 cm-1 and that for DHP was 1.699 x 10(4) M-1 cm-1. The applicability of the method was tested using different plant extracts and recovery was found to be at 100 +/- 0.3%. The method is suitable for accurate estimation of both mimosine and DHP after paper chromatographic separation of extracts of different biological samples. PMID:8238882

Lalitha, K; Vargheese, C M; Balasubramanian, N

1993-08-15