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1

Onium ions. 34. The methoxydiazonium ion: preparation, /sup 1/H, /sup 13/C, and /sup 15/N NMR and IR structural studies, theoretical calculations, and reaction with aromatics. Attempted preparation and the intermediacy of the hydroxydiazonium ion  

SciTech Connect

Nitrous oxide is methylated with CH/sub 3/F ..-->.. SbF/sub 5/F/sub 2/ or with CH/sub 3/O/sup +/SOClF in SO/sub 2/ClF to give the stable methoxydiazonium ion CH/sub 3/ON/sub 2//sup +/ (1), which was characterized by NMR (/sup 15/N, /sup 13/C, /sup 1/H) and FT IR spectroscopic studies. It is stable below -30 /sup 0/C, above which it decomposes, regenerating N/sub 2/O. When reacted with aromatics, such as toluene, 1 gives only methylation products and no methoxy derivatives are formed. Spectroscopic and chemical data indicate that the mesomeric form CH/sub 3/O-N=N/sup +/ is a significant contributor to the overall structure of 1. Consideration of computed charge distribution (4-31 G with full geometry optimization and 4-31 G*) also supports this conclusion. Independent generation of 1 was also studied by solvolysis of methylazoxy triflate and diazotization of methoxylamine with NO/sup +/BF/sub 4//sup -/. Preparation of the elusive hydroxydiazonium ion HON/sub 2//sup +/(4) was attempted by protonation of nitrous oxide in super acids, but no long-lived ion could be observed. Diazotization of hydroxylamine with NO/sup +/BF/sub 4//sup -/ gives nitrous oxide indicative of the intermediacy of 4.

Olah, G.A.; Herges, R.; Laali, K.; Segal, G.A.

1986-04-16

2

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

3

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

2011-09-30

4

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

5

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

SciTech Connect

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

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

2006-07-15

6

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

7

Reversed-phase HPLC of polymer additives with multiple on-line spectroscopic analysis (UV, IR, (1)H NMR and MS).  

PubMed

The reversed-phase chromatography of a number of polymer additives has been undertaken with on-line characterisation via a combination of diode array UV, (1)H NMR, IR spectroscopy and mass spectrometry. This combination of spectrometers enabled the on-flow collection of full UV, (1)H NMR, IR and mass spectra for a range of common polymer additives in amounts ranging from ca. 230 to 900 micro g on-column. The practical difficulties associated with multiple hyphenation and potential future developments are discussed. PMID:12172686

Louden, Dave; Handley, Alan; Lenz, Eva; Sinclair, Ian; Taylor, Steve; Wilson, Ian D

2002-07-01

8

Simultaneous 19F-1H medium resolution NMR spectroscopy for online reaction monitoring  

NASA Astrophysics Data System (ADS)

Medium resolution nuclear magnetic resonance (MR-NMR) spectroscopy is currently a fast developing field, which has an enormous potential to become an important analytical tool for reaction monitoring, in hyphenated techniques, and for systematic investigations of complex mixtures. The recent developments of innovative MR-NMR spectrometers are therefore remarkable due to their possible applications in quality control, education, and process monitoring. MR-NMR spectroscopy can beneficially be applied for fast, non-invasive, and volume integrating analyses under rough environmental conditions. Within this study, a simple 1/16? fluorinated ethylene propylene (FEP) tube with an ID of 0.04? (1.02 mm) was used as a flow cell in combination with a 5 mm glass Dewar tube inserted into a benchtop MR-NMR spectrometer with a 1H Larmor frequency of 43.32 MHz and 40.68 MHz for 19F. For the first time, quasi-simultaneous proton and fluorine NMR spectra were recorded with a series of alternating 19F and 1H single scan spectra along the reaction time coordinate of a homogeneously catalysed esterification model reaction containing fluorinated compounds. The results were compared to quantitative NMR spectra from a hyphenated 500 MHz online NMR instrument for validation. Automation of handling, pre-processing, and analysis of NMR data becomes increasingly important for process monitoring applications of online NMR spectroscopy and for its technical and practical acceptance. Thus, NMR spectra were automatically baseline corrected and phased using the minimum entropy method. Data analysis schemes were designed such that they are based on simple direct integration or first principle line fitting, with the aim that the analysis directly revealed molar concentrations from the spectra. Finally, the performance of 1/16? FEP tube set-up with an ID of 1.02 mm was characterised regarding the limit of detection (LOQ (1H) = 0.335 mol L-1 and LOQ (19F) = 0.130 mol L-1 for trifluoroethanol in D2O (single scan)) and maximum quantitative flow rates up to 0.3 mL min-1. Thus, a series of single scan 19F and 1H NMR spectra acquired with this simple set-up already presents a valuable basis for quantitative reaction monitoring.

Zientek, Nicolai; Laurain, Clément; Meyer, Klas; Kraume, Matthias; Guthausen, Gisela; Maiwald, Michael

2014-12-01

9

Simultaneous (19)F-(1)H medium resolution NMR spectroscopy for online reaction monitoring.  

PubMed

Medium resolution nuclear magnetic resonance (MR-NMR) spectroscopy is currently a fast developing field, which has an enormous potential to become an important analytical tool for reaction monitoring, in hyphenated techniques, and for systematic investigations of complex mixtures. The recent developments of innovative MR-NMR spectrometers are therefore remarkable due to their possible applications in quality control, education, and process monitoring. MR-NMR spectroscopy can beneficially be applied for fast, non-invasive, and volume integrating analyses under rough environmental conditions. Within this study, a simple 1/16? fluorinated ethylene propylene (FEP) tube with an ID of 0.04? (1.02mm) was used as a flow cell in combination with a 5mm glass Dewar tube inserted into a benchtop MR-NMR spectrometer with a (1)H Larmor frequency of 43.32MHz and 40.68MHz for (19)F. For the first time, quasi-simultaneous proton and fluorine NMR spectra were recorded with a series of alternating (19)F and (1)H single scan spectra along the reaction time coordinate of a homogeneously catalysed esterification model reaction containing fluorinated compounds. The results were compared to quantitative NMR spectra from a hyphenated 500MHz online NMR instrument for validation. Automation of handling, pre-processing, and analysis of NMR data becomes increasingly important for process monitoring applications of online NMR spectroscopy and for its technical and practical acceptance. Thus, NMR spectra were automatically baseline corrected and phased using the minimum entropy method. Data analysis schemes were designed such that they are based on simple direct integration or first principle line fitting, with the aim that the analysis directly revealed molar concentrations from the spectra. Finally, the performance of 1/16? FEP tube set-up with an ID of 1.02mm was characterised regarding the limit of detection (LOQ ((1)H)=0.335molL(-1) and LOQ ((19)F)=0.130molL(-1) for trifluoroethanol in D2O (single scan)) and maximum quantitative flow rates up to 0.3mLmin(-1). Thus, a series of single scan (19)F and (1)H NMR spectra acquired with this simple set-up already presents a valuable basis for quantitative reaction monitoring. PMID:25462947

Zientek, Nicolai; Laurain, Clément; Meyer, Klas; Kraume, Matthias; Guthausen, Gisela; Maiwald, Michael

2014-10-18

10

Synthesis of diverse indene derivatives from 1-diazonaphthalen-2(1H)-ones via thermal cascade reactions.  

PubMed

A sequential Wolff rearrangement of 1-diazonaphthalen-2(1H)-ones followed by trapping of the ketene intermediate with primary and aromatic amines or alcohols and phenols in the presence of various aldehydes generates 1H-indene-3-carboxamides or 1H-indene-3-carboxylates. This constitutes an unprecedented three-component coupling reaction that allows for the synthesis of functionalized indene derivatives under catalyst-free thermal conditions. PMID:23944353

Somai Magar, Krishna Bahadur; Lee, Yong Rok

2013-09-01

11

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

12

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

13

Study of inclusion complex between 2,6-dinitrobenzoic acid and ?-cyclodextrin by 1H NMR, 2D 1H NMR (ROESY), FT-IR, XRD, SEM and photophysical methods.  

PubMed

The formation of host-guest inclusion complex of 2,6-dinitrobenzoic acid (2,6-DNB) with nano-hydrophobic cavity of ?-cyclodextrin (?-CD) in solution phase has been studied by UV-visible spectroscopy and electrochemical analysis (cyclic voltammetry, CV). The effect of acid-base concentrations of 2,6-DNB has been studied in presence and absence of ?-CD to determination for the ground state acidity constant (pKa). The binding constant of inclusion complex at 303 K was calculated using Benesi-Hildebrand plot and thermodynamic parameter (?G) was also calculated. The solid inclusion complex formation between ?-CD and 2,6-DNB was confirmed by 1H NMR, 2D 1H NMR (ROESY), FT-IR, XRD and SEM analysis. A schematic representation of this inclusion process was proposed by molecular docking studies using patch dock server. PMID:24769381

Srinivasan, Krishnan; Stalin, Thambusamy

2014-09-15

14

Mn(II), Cu(II) and Cd(II) p-coumarates: FT-IR, FT-Raman, 1H and 13C NMR and thermogravimetric studies  

NASA Astrophysics Data System (ADS)

Manganese(II), copper(II) and cadmium(II) complexes of p-coumaric acid (p-hydroxycinnamic acid) were synthesized. Their composition was established by means of elementary and thermogravimetric analysis. To study the molecular structure of synthesized compounds many miscellaneous analytical methods, which complement one another, were used: infrared (FT-IR), Raman (FT-Raman) and nuclear magnetic resonance (1H, 13C NMR). The spectroscopic studies lead to conclusions concerning the distribution of the electronic charge in complexes in comparison with p-coumaric acid molecule and the type of metal ion coordination.

Kalinowska, M.; Laderiere, B.; Champagne, P.; Kowczyk-Sadowy, M.; Lewandowski, W.

2013-02-01

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

FT-IR, FT-Raman, dispersive Raman, NMR spectroscopic studies and NBO analysis of 2-Bromo-1H-Benzimidazol by density functional method  

NASA Astrophysics Data System (ADS)

In this study, geometrical optimization, FT-IR (4000-400 cm-1), FT-Raman (4000-40 cm-1), dispersive Raman (4000-40 cm-1) spectroscopic analysis, electronic structure and 1H and 13C nuclear magnetic resonance (NMR) studies of 2-Bromo-1H-Benzimidazol (abbreviated as 2Br1HB) were undertaken by utilizing DFT/B3LYP with 6-311+G(d,p) basis set. The results of the calculations were applied to simulate spectra of the title compound, which show good agreement with observed spectra. Complete vibrational assignments, analysis and correlations of the fundamental modes for 2Br1HB compound were carried out. Stability of the molecule arising from hyperconjugative interactions, charge delocalization was analyzed using natural bond orbital (NBO) analysis. The molecule orbital contributions were studied by using the total density of states (TDOS), partial density of states (PDOS), and overlap population density of states (OPDOS). The electronic properties like HOMO-LUMO energies and molecular electrostatic potential (MEP) analysis were reported. The calculated HOMO and LUMO energies shows that charge transfer interactions take place within the molecule. Mulliken population analysis on atomic charges was also calculated. Good correlation between the experimental 1H and 13C NMR chemical shifts in DMSO solution and calculated gauge-including atomic orbital (GIAO) shielding tensors were found.

Sas, E. B.; Kurt, M.; Karabacak, M.; Poiyamozhi, A.; Sundaraganesan, N.

2015-02-01

17

Structural study of 2-(1-oxo-1 H-inden-3-yl)-2 H-indene-1,3-dione by DFT calculations, NMR and IR spectroscopy  

NASA Astrophysics Data System (ADS)

Computational studies have been carried out at the DFT-B3LYP/6-31G(d) level of theory on the structural and spectroscopic properties of 2-(1-oxo-1 H-inden-3-yl)-2 H-indene-1,3-dione (OID). Experimental studies were conducted on these parameters, including X-ray, FT-IR and 13C NMR spectroscopy. The optimized geometries of OID and its bonding characteristics as well as IR and NMR spectra have been calculated and analyzed. It was observed that the bond lengths and angles in the molecule, obtained by X-ray, IR and NMR at the level of theory, were in a good agreement with those of the experiment. The correlation between the theoretical and the experimental vibrational frequencies and the chemical shifts of the OID molecule were 0.994 and 0.991, respectively. The agreement mutually verified the accuracy of the experimental method and the validity of the applied mathematical model.

Riahi, Siavash; Ganjali, Mohammad Reza; Moghaddam, Abdolmajid Bayandori; Norouzi, Parviz; Hosseiny Davarani, Saied Saeed

2008-06-01

18

Communication: Enhanced oxygen reduction reaction and its underlying mechanism in Pd-Ir-Co trimetallic alloys  

SciTech Connect

Based on a combined density functional theory and experimental study, we present that the electrochemical activity of Pd{sub 3}Co alloy catalysts toward oxygen reduction reaction (ORR) can be enhanced by adding a small amount of Ir. While Ir tends to favorably exist in the subsurface layers, the underlying Ir atoms are found to cause a substantial modification in the surface electronic structure. As a consequence, we find that the activation barriers of O/OH hydrogenation reactions are noticeably lowered, which would be mainly responsible for the enhanced ORR activity. Furthermore, our study suggests that the presence of Ir in the near-surface region can suppress Co out-diffusion from the Pd{sub 3}Co substrate, thereby improving the durability of Pd-Ir-Co catalysts. We also discuss the relative roles played by Ir and Co in enhancing the ORR activity relative to monometallic Pd catalysts.

Ham, Hyung Chul; Hwang, Gyeong S., E-mail: gshwang@che.utexas.edu [Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712 (United States); Manogaran, Dhivya [Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, Texas 78712 (United States)] [Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, Texas 78712 (United States); Lee, Kang Hee; Jin, Seon-ah; You, Dae Jong; Pak, Chanho [Energy Lab, Samsung Advanced Institute of Technology, Samsung Electronics Co., Ltd., Suwon (Korea, Republic of)] [Energy Lab, Samsung Advanced Institute of Technology, Samsung Electronics Co., Ltd., Suwon (Korea, Republic of); Kwon, Kyungjung [Department of Energy and Mineral Resources Engineering, Sejong University, Seoul 143-747 (Korea, Republic of)] [Department of Energy and Mineral Resources Engineering, Sejong University, Seoul 143-747 (Korea, Republic of)

2013-11-28

19

Iridium porphyrins in CD3OD: reduction of Ir(III), CD3-OD bond cleavage, Ir-D acid dissociation and alkene reactions.  

PubMed

Methanol solutions of iridium(III) tetra(p-sulfonatophenyl)porphyrin [(TSPP)Ir(III)] form an equilibrium distribution of methanol and methoxide complexes ([(TSPP)Ir(III)(CD3OD)(2-n)(OCD3)n]((3+n)-)). Reaction of [(TSPP)Ir(III) with dihydrogen (D2) in methanol produces an iridium hydride [(TSPP)Ir(III)-D(CD3OD)](4-) in equilibrium with an iridium(I) complex ([(TSPP)Ir(I)(CD3OD)](5-)). The acid dissociation constant of the iridium hydride (Ir-D) in methanol at 298 K is 3.5 × 10(-12). The iridium(I) complex ([(TSPP)Ir(I)(CD3OD)](5-)) catalyzes reaction of [(TSPP)Ir(III)-D(CD3OD)](4-) with CD3-OD to produce an iridium methyl complex [(TSPP)Ir(III)-CD3(CD3OD)](4-) and D2O. Reactions of the iridium hydride with ethene and propene produce iridium alkyl complexes, but the Ir-D complex fails to give observable addition with acetaldehyde and carbon monoxide in methanol. Reaction of the iridium hydride with propene forms both the isopropyl and propyl complexes with free energy changes (?G° 298 K) of -1.3 and -0.4 kcal mol(-1) respectively. Equilibrium thermodynamics and reactivity studies are used in discussing relative Ir-D, Ir-OCD3 and Ir-CD2- bond energetics in methanol. PMID:23540797

Bhagan, Salome; Imler, Gregory H; Wayland, Bradford B

2013-04-15

20

Investigation of the Exclusive {sup 3}He(e,e{sup '}pn){sup 1}H Reaction  

SciTech Connect

Cross sections for the {sup 3}He(e,e{sup '}pn){sup 1}H reaction were measured for the first time at energy transfers of 220 and 270 MeV for several momentum transfers ranging from 300 to 450 MeV/c. Cross sections are presented as a function of the momentum of the recoil proton and the momentum transfer. Continuum Faddeev calculations using the Argonne V18 and Bonn-B nucleon-nucleon potentials overestimate the measured cross sections by a factor 5 at low recoil proton momentum with the discrepancy becoming smaller at higher recoil proton momentum.

Middleton, D. G.; Grabmayr, P.; Hehl, T.; Heim, J.; Martin, I.; Moschini, F. [Kepler Centre for Astro and Particle Physics, Physikalisches Institut, Universitaet Tuebingen, D-72076 Tuebingen (Germany); Annand, J. R. M.; Glazier, D. I.; MacGregor, I. J. D.; McGeorge, J. C.; Monstad, K.; Rosner, G.; Watts, D. P. [Department of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, Scotland (United Kingdom); Antelo, M. Ases; Ayerbe, C.; Baumann, D.; Bermuth, J.; Bernauer, J.; Boehm, R.; Ding, M. [Institut fuer Kernphysik, Johannes Gutenberg-Universitaet Mainz, D-55099 Mainz (Germany)

2009-10-09

21

Quantum mechanical and spectroscopic (FT-IR, FT-Raman, 13C, 1H and UV) investigations of antiepileptic drug Ethosuximide  

NASA Astrophysics Data System (ADS)

The Fourier Transform Infrared (FT-IR) and Fourier Transform Raman (FT-Raman) spectra of antiepileptic drug Ethosuximide (ETX) have been recorded and analyzed. In addition, the IR spectra in CCl 4 at various concentrations of ETX are also recorded. The equilibrium geometry, bonding features and harmonic vibrational frequencies have been investigated with the help of Density Functional Theory (DFT) method. The 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by the Gauge Including 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 charge in electron density (ED) in the ? * and ? * antibonding orbitals and second order delocalization energies E(2) confirms 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 performed by Time-Dependent Density Functional Theory (TD-DFT) approach. Finally the calculation results were applied to simulate infrared and Raman spectra of the title compound which showed good agreement with observed spectra.

Vijaya Chamundeeswari, S. P.; James Jebaseelan Samuel, E.; Sundaraganesan, N.

2011-12-01

22

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

23

Synthesis of 1-(R-Phenyl)-5-(R-Methyl)-1H-1,2,3-triazole-4-carboxylic Acids by One-Pot Tandem Reaction  

Microsoft Academic Search

Substituted 1H-1,2,3-triazole-4-carboxylic acids were synthesized by a three-component reaction of arylazides, ethyl 4-chloro-3-oxobutanoate, and either O- or S-nucleophiles in the presence of a base catalyst. The reaction most probably proceeded as a [3 + 2] cyclocondensation reaction between arylazide and ethyl 4-chloro-3-oxobutanoate with the further nucleophilic substitution of chlorine in the chloromethyl group. Reaction optimization was performed to carry out the reaction

Nazariy T. Pokhodylo; Vasyl S. Matiychuk; Mykola D. Obushak

2010-01-01

24

The CIELO Collaboration:Neutron Reactions on 1H, 16O, 56Fe, 235,238U, and 239Pu  

SciTech Connect

CIELO (Collaborative International Evaluated Library Organization) provides a new working paradigm to facilitate evaluated nuclear reaction data advances. It brings together experts from across the international nuclear reaction data community to identify and document discrepancies among existing evaluated data libraries, measured data, and model calculation interpretations, and aims to make progress in reconciling these discrepancies to create more accurate ENDF-formatted files. The focus will initially be on a small number of the highest-priority isotopes, namely 1H, 16O, 56Fe, 235,238U, and 239Pu. This paper identifies discrepancies between various evaluations of the highest priority isotopes, and was commissioned by the OECD's Nuclear Energy Agency WPEC (Working Party on International Nuclear Data Evaluation Co-operation) during a meeting held in May 2012. The evaluated data for these materials in the existing nuclear data libraries — ENDF/B-VII.1, JEFF-3.1, JENDL-4.0, CENDL-3.1, ROSFOND, IRDFF 1.0 — are reviewed, discrepancies are identified, and some integral properties are given. The paper summarizes a program of nuclear science and computational work needed to create the new CIELO nuclear data evaluations.

Giuseppe Palmiotti; M. B. Chadwick

2014-04-01

25

The CIELO Collaboration: Neutron Reactions on 1H, 16O, 56Fe, 235,238U, and 239Pu  

NASA Astrophysics Data System (ADS)

CIELO (Collaborative International Evaluated Library Organization) provides a new working paradigm to facilitate evaluated nuclear reaction data advances. It brings together experts from across the international nuclear reaction data community to identify and document discrepancies among existing evaluated data libraries, measured data, and model calculation interpretations, and aims to make progress in reconciling these discrepancies to create more accurate ENDF-formatted files. The focus will initially be on a small number of the highest-priority isotopes, namely 1H, 16O, 56Fe, 235,238U, and 239Pu. This paper identifies discrepancies between various evaluations of the highest priority isotopes, and was commissioned by the OECD's Nuclear Energy Agency WPEC (Working Party on International Nuclear Data Evaluation Co-operation) during a meeting held in May 2012. The evaluated data for these materials in the existing nuclear data libraries - ENDF/B-VII.1, JEFF-3.1, JENDL-4.0, CENDL-3.1, ROSFOND, IRDFF 1.0 - are reviewed, discrepancies are identified, and some integral properties are given. The paper summarizes a program of nuclear science and computational work needed to create the new CIELO nuclear data evaluations.

Chadwick, M. B.; Dupont, E.; Bauge, E.; Blokhin, A.; Bouland, O.; Brown, D. A.; Capote, R.; Carlson, A.; Danon, Y.; De Saint Jean, C.; Dunn, M.; Fischer, U.; Forrest, R. A.; Frankle, S. C.; Fukahori, T.; Ge, Z.; Grimes, S. M.; Hale, G. M.; Herman, M.; Ignatyuk, A.; Ishikawa, M.; Iwamoto, N.; Iwamoto, O.; Jandel, M.; Jacqmin, R.; Kawano, T.; Kunieda, S.; Kahler, A.; Kiedrowski, B.; Kodeli, I.; Koning, A. J.; Leal, L.; Lee, Y. O.; Lestone, J. P.; Lubitz, C.; MacInnes, M.; McNabb, D.; McKnight, R.; Moxon, M.; Mughabghab, S.; Noguere, G.; Palmiotti, G.; Plompen, A.; Pritychenko, B.; Pronyaev, V.; Rochman, D.; Romain, P.; Roubtsov, D.; Schillebeeckx, P.; Salvatores, M.; Simakov, S.; Soukhovitski?˜, E. Sh.; Sublet, J. C.; Talou, P.; Thompson, I.; Trkov, A.; Vogt, R.; van der Marck, S.

2014-04-01

26

Conformational analysis, spectroscopic study (FT-IR, FT-Raman, UV, 1H and 13C NMR), molecular orbital energy and NLO properties of 5-iodosalicylic acid  

NASA Astrophysics Data System (ADS)

In this study, 5-iodosalicylic acid (5-ISA, C7H5IO3) is structurally characterized by FT-IR, FT-Raman, NMR and UV spectroscopies. There are eight conformers, Cn, n = 1-8 for this molecule therefore the molecular geometry for these eight conformers in the ground state are calculated by using the ab-initio density functional theory (DFT) B3LYP method approach with the aug-cc-pVDZ-PP basis set for iodine and the aug-cc-pVDZ basis set for the other elements. The computational results identified that the most stable conformer of 5-ISA is the C1 form. The vibrational spectra are calculated DFT method invoking the same basis sets and fundamental vibrations are assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method with PQS program. Total density of state (TDOS) and partial density of state (PDOS) and also overlap population density of state (COOP or OPDOS) diagrams analysis for C1 conformer were calculated using the same method. The energy and oscillator strength are calculated by time-dependent density functional theory (TD-DFT) results complement with the experimental findings. Besides, charge transfer occurring in the molecule between HOMO and LUMO energies, frontier energy gap, molecular electrostatic potential (MEP) are calculated and presented. The NMR chemical shifts (1H and 13C) spectra are recorded and calculated using the gauge independent atomic orbital (GIAO) method. Mulliken atomic charges of the title molecule are also calculated, interpreted and compared with salicylic acid. The optimized bond lengths, bond angles and calculated NMR and UV, vibrational wavenumbers showed the best agreement with the experimental results.

Karaca, Caglar; Atac, Ahmet; Karabacak, Mehmet

2015-02-01

27

Dynamic biochemical information recovery in spontaneous human seminal fluid reactions via 1H NMR kinetic statistical total correlation spectroscopy.  

PubMed

Human seminal fluid (HSF) is a complex mixture of reacting glandular metabolite and protein secretions that provides critical support functions in fertilization. We have employed 600-MHz (1)H NMR spectroscopy to compare and contrast the temporal biochemical and biophysical changes in HSF from infertile men with spinal cord injury compared to age-matched controls. We have developed new approaches to data analysis and visualization to facilitate the interpretation of the results, including the first application of the recently published K-STOCSY concept to a biofluid, enhancing the extraction of information on biochemically related metabolites and assignment of resonances from the major seminal protein, semenogelin. Principal components analysis was also applied to evaluate the extent to which macromolecules influence the overall variation in the metabolic data set. The K-STOCSY concept was utilized further to determine the relationships between reaction rates and metabolite levels, revealing that choline, N-acetylglucosamine, and uridine are associated with higher peptidase activity. The novel approach adopted here has the potential to capture dynamic information in any complex mixture of reacting chemicals including other biofluids or cell extracts. PMID:19117456

Maher, Anthony D; Cloarec, Olivier; Patki, Prasad; Craggs, Michael; Holmes, Elaine; Lindon, John C; Nicholson, Jeremy K

2009-01-01

28

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

29

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...

30

Nanosized IrO 2 electrocatalysts for oxygen evolution reaction in an SPE electrolyzer  

Microsoft Academic Search

Nanosized IrO2 electrocatalysts (d ~ 7–9 nm) with specific surface area up to 100 m2 g?1 were synthesized and characterized for the oxygen evolution reaction in a solid polymer electrolyte (SPE) electrolyzer. The\\u000a catalysts were prepared by a colloidal method in aqueous solution and a subsequent thermal treatment. An iridium hydroxide\\u000a hydrate precursor was obtained at ~100 °C, which was, successively, calcined at different temperatures from

J. C. Cruz; V. Baglio; S. Siracusano; R. Ornelas; L. Ortiz-Frade; L. G. Arriaga; V. Antonucci; A. S. Aricò

2011-01-01

31

Reaction Rate Prediction via Group Additivity Part 1H Abstraction from Alkanes by H and CH 3  

Microsoft Academic Search

Reliable estimates of high-pressure-limit reaction rates as a function of temperature are essential for the development of reaction sets that can be used to model complex chemical processes. As these reaction rates depend primarily on the thermodynamic properties of the reactants and the corresponding transition state, this work attempts to predict these properties within the framework of group additivity. Using

R. Sumathi; H.-H. Carstensen

2001-01-01

32

The spectroscopic (FT-IR, FT-Raman, l3C, 1H NMR and UV) and NBO analyses of 4-bromo-1-(ethoxycarbonyl)piperidine-4-carboxylic acid  

NASA Astrophysics Data System (ADS)

In this work, we will report a combined experimental and theoretical study on molecular and vibrational structure of 4-bromo-1-(ethoxycarbonyl)piperidine-4-carboxylic acid (BEPA). BEPA has been characterized by FT-IR, FT-Raman, 1H NMR, 13C NMR and UV spectroscopy. The FT-IR and FT-Raman spectra of BEPA were recorded in the solid phase. The optimized geometry was calculated by B3LYP and M06-2X methods using 6-311G(d,p) basis set. The FT-IR and FT-Raman spectra of BEPA were calculated at the same level and were interpreted in terms of Potential Energy Distribution (PED) analysis. The scaled theoretical wavenumber showed very good agreement with the experimental values. The 1H and l3C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by the Gauge-Independent Atomic Orbital (GIAO) method. Stability of the molecule arising from hyperconjugative interactions and charge delocalization has been analyzed using Natural Bond Orbital (NBO) analysis. Density plots over the highest occupied molecular orbitals (HOMO) and lowest unoccupied molecular orbitals (LUMO) energy surface directly identifies the donor and acceptor atoms in the molecule. It also provides information about the charge transfer within the molecule. To obtain chemical reactivity of the molecule, the molecular electrostatic potential (MEP) surface map is plotted over the optimized geometry of the molecule.

Vitnik, Vesna D.; Vitnik, Željko J.

2015-03-01

33

The spectroscopic (FT-IR, FT-Raman, (l3)C, (1)H NMR and UV) and NBO analyses of 4-bromo-1-(ethoxycarbonyl)piperidine-4-carboxylic acid.  

PubMed

In this work, we will report a combined experimental and theoretical study on molecular and vibrational structure of 4-bromo-1-(ethoxycarbonyl)piperidine-4-carboxylic acid (BEPA). BEPA has been characterized by FT-IR, FT-Raman, (1)H NMR, (13)C NMR and UV spectroscopy. The FT-IR and FT-Raman spectra of BEPA were recorded in the solid phase. The optimized geometry was calculated by B3LYP and M06-2X methods using 6-311G(d,p) basis set. The FT-IR and FT-Raman spectra of BEPA were calculated at the same level and were interpreted in terms of Potential Energy Distribution (PED) analysis. The scaled theoretical wavenumber showed very good agreement with the experimental values. The (1)H and (l3)C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by the Gauge-Independent Atomic Orbital (GIAO) method. Stability of the molecule arising from hyperconjugative interactions and charge delocalization has been analyzed using Natural Bond Orbital (NBO) analysis. Density plots over the highest occupied molecular orbitals (HOMO) and lowest unoccupied molecular orbitals (LUMO) energy surface directly identifies the donor and acceptor atoms in the molecule. It also provides information about the charge transfer within the molecule. To obtain chemical reactivity of the molecule, the molecular electrostatic potential (MEP) surface map is plotted over the optimized geometry of the molecule. PMID:25434858

Vitnik, Vesna D; Vitnik, Željko J

2015-03-01

34

Efficient synthesis of functionalized dihydro-1H-indol-4(5H)-ones via one-pot three-component reaction under catalyst-free conditions.  

PubMed

A facile and efficient one-pot procedure for the preparation of functionalized dihydro-1H-indol-4(5H)-ones by a catalyst-free, three-component reaction of 1,3-dicarbonyl compounds, arylglyoxal monohydrate and enaminones under mild conditions in excellent yield is reported. This synthesis was confirmed to follow the group-assisted-purification (GAP) chemistry process, which can avoid traditional purifications, chromatography, and recrystallization. PMID:23597107

Wang, Hui-Yan; Shi, Da-Qing

2013-05-13

35

The 1H(11B,n)11C reaction as a practical low background monoenergetic neutron source in the 10 MeV region  

Microsoft Academic Search

Neutron source properties of the 1H(11B,n)11C reaction were measured for incident 11B energies between 50 and 64 MeV by detecting the neutrons at angles of 0° to 40°. Neutron were produced with high monochromaticity in the range of several MeV to 12 MeV. In addition, the room background is very low because they were collimated to a forward cone according

Satoshi Chiba; Motoharu Mizumoto; Kazuo Hasegawa; Yoshimaro Yamanouti; Masayoshi Sugimoto; Yukinobu Watanabe; Manfred Drosg

1989-01-01

36

The reaction of Hg(6 3P1)+H2, D2, and HD: Product rotational and vibrational distributions; isotope effects  

NASA Astrophysics Data System (ADS)

The initial vibrational and rotational state distributions of HgH and HgD products of Hg(6 3P1)+H2, D2, and HD have been determined. No isotope effect was observed for the vibrationless molecules or for HgH(v=1) but this effect appears for vibrationally excited HgD. The relative yields of the various reactions are reported for each vibrational level. In the reaction with HD, HgD is preferentially produced: [HgD]/[HgH]?6.7.

Bras, N.; Jeannet, J. C.; Perrin, D.

1987-07-01

37

Probing the Reaction Pathway of Dehydrogenation of the LiNH2 + LiH Mixture Using In Situ 1H NMR Spectroscopy  

SciTech Connect

Using variable temperature in situ 1H NMR spectroscopy on a mixture of LiNH2 + LiH that was mechanically activated using high energy ball milling, the dehydrogenation of the LiNH2 + LiH to Li2NH + H2 was investigated. The analysis indicates NH3 release at a temperature as low as 300C and rapid reaction between NH3 and LiH at ~ 1500C. The transition from NH3 release to H2 appearance accompanied by disappearance of NH3 confirms unambiguously the two-step elementary reaction pathway proposed by other workers.

Hu, Jian Zhi; Kwak, Ja Hun; Yang, Zhenguo; osborn, william; Markmaitree, Tippawan; Shaw, Leonard D.

2008-06-15

38

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

39

IR spectrum and localization of excitation of reaction center of photosystem II in triplet state  

NASA Astrophysics Data System (ADS)

Using the density functional theory, vibrations of different model forms of the chlorophyll a molecule in the ground and triplet states have been calculated. The assignment of the experimental difference IR spectrum corresponding to the formation of the triplet state of the photosynthetic reaction center of photosystem II has been proposed on this basis. It has been shown that molecules of accessory chlorophyll B A and B B located between the special pair and H A and H B pheophytin molecules can be involved in the intermolecular hydrogen bond with the water molecule. The energy of this interaction in the triplet state of molecules for B A is larger on 6 kcal/mol. This allows us to relate this pigment to the location of the triplet excitation at the reaction center of photosystem II.

Ivashin, N. V.

2010-04-01

40

Combined experimental and theoretical studies on the X-ray crystal structure, FT-IR, 1H NMR, 13C NMR, UV-Vis spectra, NLO behavior and antimicrobial activity of 2-hydroxyacetophenone benzoylhydrazone.  

PubMed

A Schiff base ligand, 2-hydroxyacetophenone benzoylhydrazone (HL) was synthesized and fully characterized with FT-IR, elemental analyses, UV-Vis, (1)H NMR and (13)C NMR spectra. DFT calculations using B3LYP/6-31+G(d,p) and PW91/DZP are performed to optimize the molecular geometry. Optimized structures are used to calculate FT-IR, UV-Vis, (1)H NMR and (13)C NMR spectra of the compound. Also the energies of the frontier molecular orbitals (FMOs) have been determined. The results obtained from the optimization and spectral analyses are in good agreement with the experimental data. To investigate non-linear optical properties, the electric dipole moment (?), polarizability (?) and molecular first hyperpolarizability (?) were computed. The linear polarizabilities and first hyperpolarizabilities of the studied molecule indicate that the compound can be a good candidate of nonlinear optical materials. In addition, the minimal inhibitory concentration (MIC) of this compound against Staphylococcus aureus, and Candida albicans was determined. PMID:24508893

Sheikhshoaie, Iran; Ebrahimipour, S Yousef; Sheikhshoaie, Mahdeyeh; Rudbari, Hadi Amiri; Khaleghi, Moj; Bruno, Giuseppe

2014-04-24

41

Vibrational (FT-IR and FT-Raman), electronic (UV-Vis), NMR (1H and 13C) spectra and reactivity analyses of 4,5-dimethyl-o-phenylenediamine.  

PubMed

The structure of 4,5-dimethyl-o-phenylenediamine (C8H12N2, DMPDA) was investigated on the basis of spectroscopic data and theoretical calculations. The sterochemical structure was determined by FT-IR, FT-Raman, UV, 1H and 13C NMR spectra. An experimental study and a theoretical analysis were associated by using the B3LYP method with Gaussian09 package program. FT-IR and FT-Raman spectra were recorded in the region of 4000-400 cm(-1) and 4000-10 cm(-1), respectively. The vibrational spectra were calculated by DFT method and the fundamental vibrations were assigned on the basis of the total energy distribution (TED), calculated with scaled quantum mechanics (SQM) method with Parallel Quantum Solutions (PQS) program. The UV absorption spectrum of the compound that dissolved in ethanol solution were recorded in the range of 190-400 nm. Total density of state (TDOS) and partial density of state (PDOS) of the DMPDA in terms of HOMOs and LUMOs were calculated and analyzed. Chemical shifts were reported in ppm relative to tetramethylsilane (TMS) for 1H and 13C NMR spectra. The compound was dissolved in dimethyl sulfoxide (DMSO). Also, 1H and 13C chemical shifts calculated using the gauge independent atomic orbital (GIAO) method. Mullikan atomic charges and other thermo-dynamical parameters were investigated with the help of B3LYP (DFT) method using 6-311++G** basis set. On the basis of the thermodynamic properties of the title compound at different temperatures have been carried out, revealing the correlations between heat capacity (C), entropy (S), enthalpy changes (H) and temperatures. The optimized bond lengths, bond angles, chemical shifts and vibrational wavenumbers showed the best agreement with the experimental results. PMID:24813280

Atac, Ahmet; Karaca, Caglar; Gunnaz, Salih; Karabacak, Mehmet

2014-09-15

42

Vibrational (FT-IR and FT-Raman), electronic (UV-Vis), NMR (1H and 13C) spectra and reactivity analyses of 4,5-dimethyl-o-phenylenediamine  

NASA Astrophysics Data System (ADS)

The structure of 4,5-dimethyl-o-phenylenediamine (C8H12N2, DMPDA) was investigated on the basis of spectroscopic data and theoretical calculations. The sterochemical structure was determined by FT-IR, FT-Raman, UV, 1H and 13C NMR spectra. An experimental study and a theoretical analysis were associated by using the B3LYP method with Gaussian09 package program. FT-IR and FT-Raman spectra were recorded in the region of 4000-400 cm-1 and 4000-10 cm-1, respectively. The vibrational spectra were calculated by DFT method and the fundamental vibrations were assigned on the basis of the total energy distribution (TED), calculated with scaled quantum mechanics (SQM) method with Parallel Quantum Solutions (PQS) program. The UV absorption spectrum of the compound that dissolved in ethanol solution were recorded in the range of 190-400 nm. Total density of state (TDOS) and partial density of state (PDOS) of the DMPDA in terms of HOMOs and LUMOs were calculated and analyzed. Chemical shifts were reported in ppm relative to tetramethylsilane (TMS) for 1H and 13C NMR spectra. The compound was dissolved in dimethyl sulfoxide (DMSO). Also, 1H and 13C chemical shifts calculated using the gauge independent atomic orbital (GIAO) method. Mullikan atomic charges and other thermo-dynamical parameters were investigated with the help of B3LYP (DFT) method using 6-311++G** basis set. On the basis of the thermodynamic properties of the title compound at different temperatures have been carried out, revealing the correlations between heat capacity (C), entropy (S), enthalpy changes (H) and temperatures. The optimized bond lengths, bond angles, chemical shifts and vibrational wavenumbers showed the best agreement with the experimental results.

Atac, Ahmet; Karaca, Caglar; Gunnaz, Salih; Karabacak, Mehmet

2014-09-01

43

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

44

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

NASA Astrophysics Data System (ADS)

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

Cinar, Mehmet; Coruh, Ali; Karabacak, Mehmet

2011-12-01

45

Role of cluster size and substrate in the gas phase CC bond coupling reactions of allyl halides mediated by Agn+ and Agn-1H+ cluster cations  

NASA Astrophysics Data System (ADS)

Previous studies have demonstrated that the silver hydride cluster cation Ag4H+ promotes CC bond coupling of allylbromide [G.N. Khairallah, R.A.J. O'Hair, Angewandte Chemie International Edition 44 (2005) 728]. Here the influence of both the nature and the size of the silver cluster cation and the substrate on CC bond coupling are examined. Thus each of the cations Ag2H+, Ag4H+, Ag3+, and Ag5+ were allowed to react with three different halides: allyl chloride, allyl bromide and allyl iodide. No CC bond coupling is observed in the reactions of the cluster cations with allyl chloride. There are four main reaction sequences that result in CC bond coupling for allyl bromide and allyl iodide mediated by Agn+ and Agn-1H+ clusters: (i) A sequence involving the reactions of silver cluster cations with two molecules of C3H5X: Agn+ --> Agn(C3H5X)+ --> AgnX2+. This only occurs in the cases of: n = 3 and X = I; n = 5 and X = Br. (ii) A sequence involving the reactions of silver cluster cations with two molecules of C3H5X via an organometallic intermediate: Agn+ --> Agn-1(C3H5)+ --> Agn-1X+. This only occurs in the cases of: n = 5 and X = Br and I. (iii) A sequence involving the reactions of silver hydride cluster cations with three molecules of C3H5X: Agn-1H+ --> Agn-1X+ --> Agn-1X(C3H5X)+ --> Ag(C3H5)2+ and Agn-1X3+. This only occurs in the cases of: n = 5 and X = Br and I. (iv) A sequence involving the reactions of silver hydride cluster cations with three molecules of C3H5X via an organometallic intermediate: Agn-1H+ --> Agn-1X+ --> Agn-3(C3H5)+ --> Ag(C3H5)2+ and Agn-3X+. This only occurs in the cases of: n = 5 and X = I.

Wang, Farrah Qiuyun; Khairallah, George N.; O'Hair, Richard A. J.

2009-06-01

46

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

47

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

PubMed

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

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

2013-06-01

48

Spectroscopic investigation (FT-IR and FT-Raman), vibrational assignments, HOMO-LUMO, NBO, MEP analysis and molecular docking study of 2-(4-hydroxyphenyl)-4,5-dimethyl-1H-imidazole 3-oxide.  

PubMed

In this work, the vibrational spectral analysis was carried out using FT-IR and FT-Raman spectroscopy of 2-(4-hydroxyphenyl)-4,5-dimethyl-1H-imidazole 3-oxide. The computations were performed at DFT levels of theory to get the optimized geometry and vibrational frequencies of the normal modes of the title compound using Gaussian09 software. The complete vibrational assignments of frequencies were made on the basis of potential energy distribution. The calculated HOMO and LUMO energies show the chemical activity of the molecule. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis. The hyperpolarizability values are reported and the first hyperpolarizability of the title compound is 19.61 times that of standard NLO material urea. From the MEP plot, the negative charge covers the nitro group and the positive region is over the hydroxyl group and N-H part of the imidazole ring. The calculated (1)H NMR results are in good agreement with experimental data. Molecular docking study is also reported. PMID:25819320

Benzon, K B; Varghese, Hema Tresa; Panicker, C Yohannan; Pradhan, Kiran; Tiwary, Bipransh Kumar; Nanda, Ashis Kumar; Alsenoy, C Van

2015-07-01

49

Di-n-butyltin(IV) Complexes Derived from Heterocyclic ?-diketones and N-Phthaloyl Amino Acids: Preparation, Biological Evaluation, Structural Elucidation Based upon Spectral [IR, NMR (1H, 13C, 19F and 119Sn)] Studies  

PubMed Central

Stable, six coordinated Bu2SnLA type complexes have been prepared [where LH = RCOC:C(OH)N(C6 H5)N:CCH3; R = -4-F-C6H4-(L1H), R = -4-Cl-C6H4-(L2H), R= -4-Br-C6H4-(L3H), R=-CF3(L4H) and AH = C(O)C6 H4 C(O)NCHR'COOH; R'= -H(A1H), -CH3(A2H), -CH(CH3)2(A3H)] by the interaction of 1:1:1 molar ratios of di-n-butyltin(IV) dichloride with corresponding organic moieties in refluxing benzene using two moles of Et3N as a base. In these complexes LH and AH behave as bidentate and coordination is taking place through oxygen, this is inferred from IR and 13C NMR studies. These complexes possess tin atoms in skew trapezoidal bipyramidal geometry with the C-Sn-C angles ranging from 149.88° to 156.84°. Some of these complexes with their corresponding organic moieties (LH, AH) were tested for their antimicrobial activities. PMID:18365100

Verma, Shashi; Gaurb, R. B.; Sharma, R. R.

2005-01-01

50

Quantum mechanical calculations and spectroscopic (FT-IR, FT-Raman and UV) investigations, molecular orbital, NLO, NBO, NLMO and MESP analysis of 4-[5-(4-methylphenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl] benzene-1-sulfonamide  

NASA Astrophysics Data System (ADS)

The molecular structural parameters and vibrational frequencies of the fundamental modes of 4-[5-(4-methylphenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl] benzene-1-sulfonamide(abbreviated as 4MPTFM1HPB1SA) have been obtained using Density functional theory (DFT) technique in the B3LYP approximation with 6-311G(d,p) and 6-311++G(d,p) basis sets. Detailed vibrational assignments of the observed FT-IR and FT-Raman bands have been proposed on the basis of potential energy distribution (PED). The difference between the observed and the calculated wavenumbers values are very small. The theoretically predicted FT-IR and FT-Raman spectra of the title molecule have been constructed. The molecular electrostatic potential has been mapped primarily for predicting sites and relative reactivities toward electrophilic and nucleophilic attack. The intramolecular contacts have been interpreted using Natural Bond Orbital (NBO) and Natural Localized Molecular Orbital (NLMO) analysis. Important non-linear properties such as electric dipolemoment and first hyperpolarizability of 4MPTFM1HPB1SA have been computed using B3LYP quantum chemical calculation. The absorption wavelength, energy and oscillator's strength are calculated by TD-DFT and 4MPTFM1HPB1SA is approach complement with the experimental findings. The temperature dependence of thermodynamic properties has been analyzed. The Natural charges, Frontier molecular orbitals (FMOs), chemical hardness (?), chemical potential (?), Electro negativity (?) and electrophilicity values (?) are calculated and reported.

Govindasamy, P.; Gunasekaran, S.

2015-02-01

51

Using surface segregation to design stable Ru-Ir oxides for the oxygen evolution reaction in acidic environments.  

PubMed

The methods used to improve catalytic activity are well-established, however elucidating the factors that simultaneously control activity and stability is still lacking, especially for oxygen evolution reaction (OER) catalysts. Here, by studying fundamental links between the activity and stability of well-characterized monometallic and bimetallic oxides, we found that there is generally an inverse relationship between activity and stability. To overcome this limitation, we developed a new synthesis strategy that is based on tuning the near-surface composition of Ru and Ir elements by surface segregation, thereby resulting in the formation of a nanosegregated domain that balances the stability and activity of surface atoms. We demonstrate that a Ru0.5Ir0.5 alloy synthesized by using this method exhibits four-times higher stability than the best Ru-Ir oxygen evolution reaction materials, while still preserving the same activity. PMID:25297010

Danilovic, Nemanja; Subbaraman, Ramachandran; Chang, Kee Chul; Chang, Seo Hyoung; Kang, Yijin; Snyder, Joshua; Paulikas, Arvydas Paul; Strmcnik, Dusan; Kim, Yong Tae; Myers, Deborah; Stamenkovic, Vojislav R; Markovic, Nenad M

2014-12-15

52

Kinetic study of the reaction CH (X 2Pi) + H2 yields CH2 (X 3B1) + H in the temperature range 372 to 675 K  

NASA Technical Reports Server (NTRS)

The kinetics of the reversible reaction CH (X 2Pi) + H2 yields CH2 (X 3B1) + H at 372-675 K and total pressure 100 torr (mainly Ar) is investigated experimentally. The ground-state CH radicals are produced by photolysis of CHBr3 using 10-mJ 266-nm laser pulses (repetition rate 10 Hz) and monitored by measuring the fluorescence induced by a 429.8-nm dye laser, in the apparatus described by Berman et al. (1982) and Berman and Lin (1984). The results are presented in tables and graphs and characterized. The absolute rate constants for the forward and reverse reactions are determined, and their temperature dependence is given by Arrhenius expressions and formulas obtained in transition-state-theory calculations. The heat of formation of CH2 at 0 K is estimated (assuming that the recombination reaction CH2 + H has zero activation energy) as 92.6 + or - 0.5 kcal/mol.

Zabarnick, S.; Fleming, J. W.; Lin, M. C.

1986-01-01

53

Structure Determination and Excited State Proton Transfer Reaction of 1-NAPHTHOL-AMMONIA Clusters in the S_{1} State Studied by Uv-Ir Mid-Ir Spectroscopy  

NASA Astrophysics Data System (ADS)

1-naphthol ammonia clusters have been studied long time as a benchmark system of the excited state proton transfer (ESPT) reactions. Understanding the ESPT reaction in this system has still not been fully established. To detect the cluster size dependence of the S_{1} state properties, many researcher extensively investigated such as emission spectra, lifetime, solvents (ammonia) evaporation pattern. Curiously, cluster structure that is fundamental to discuss the reaction has not been determined for the system. Thus we applied an IR spectroscopy to the S_{1} states of the system to determine the cluster structure and to discuss the minimum size inducing the ionic dissociation of the O-H bond in the S_{1} state. IR spectra were recorded not only the O-H and N-H stretching region (3 {?}m) but also the skeletal vibrational region (5.5-10 {?}m). Though O-H and N-H stretching vibrations do not provide useful structural information due to the broadness, the skeletal vibrations hold the sharpness even in the S_{1} states. Changes in the skeletal vibrations due to the ammonia solvation, e.g. C-O stretching and C-O-H bending, will be discussed based on a comparison with theoretical calculations. O. Cheshnovsky and S. Leutwylar, J. Chem. Phys. 1, 4127 (1988). S. K. Kim et al., Chem. Phys. lett. 228, 369 (1994). C. Dedonder-Lardeux et al., Phys. Chem, Chem, Phys. 3, 4316 (2001).

Yoshikawa, Shunpei; Miyazaki, Mitsuhiko; Martin, Weiler; Ishikawa, Haruki; Fujii, Masaaki

2013-06-01

54

H2O2-promoted reactions of aliphatic primary amines with 1,3-diketones for the synthesis of 1H-pyrrol-3(2H)-ones at ambient temperature in water.  

PubMed

A green organic reaction of aliphatic primary amines with 1,3-diketones promoted by 30% aqueous H2O2 has been developed. It provides an inexpensive, regioselective, and efficient approach to 1H-pyrrol-3(2H)-ones with high yields from the simple and readily available starting materials in one pot via multicomponent tandem cyclization reactions and C-C cleavage under very mild and environmentally friendly reaction conditions. PMID:24702671

Sun, Xi; Li, Pinhua; Zhang, Xiuli; Wang, Lei

2014-04-18

55

Crystal structure, FT-IR, FT-Raman, 1H NMR and computational study of ethyl 2-{[(Z)3-(4-chlorophenyl)-3-hydroxy-2-propene-1-thione] amino} acetate  

NASA Astrophysics Data System (ADS)

The molecular structure of a thioamide derivative ethyl 2-{[(Z)3-(4-chlorophenyl)-3-hydroxy-2-propene-1-thione] amino} acetate was determined by X-ray diffraction. The proton NMR (1H NMR), Fourier Transform Infra-Red (FT-IR) and Fourier Transform Raman (FT-Raman) spectra of the compound were recorded and analyzed. The conjugated enol form of the compound was crystallized in the monoclinic space group P21/c, with unit cell dimensions a = 12.514(2) Å, b = 5.403(5) Å, c = 21.233(3) Å, ? = 94.597(4)°. The structure was solved by direct methods and refined to the R value of 0.0462. The thioamide moiety in the compound adopts the Z-conformation and the Csbnd N bond shows a high rotational barrier. The geometry in the gas phase was optimized by B3LYP and RHF quantum mechanical calculations using Gaussian 09 programme and the vibrational frequencies were calculated. The experimental and theoretical data are in good agreement.

Prasanth, S.; Varughese, Mary; Joseph, Nirmala; Mathew, Paulson; Manojkumar, T. K.; Sudarsanakumar, C.

2015-02-01

56

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

57

Quantum mechanical study and spectroscopic (FT-IR, FT-Raman, 13C, 1H) study, first order hyperpolarizability, NBO analysis, HOMO and LUMO analysis of 2-acetoxybenzoic acid by density functional methods  

NASA Astrophysics Data System (ADS)

In this work, colorless crystals of 2-acetoxybenzoic acid were grown by slow evaporation method and the FT-IR and FT-Raman spectra of the sample were recorded in the region 4000-500 cm-1 and 4000-100 cm-1 respectively. Molecular structure is optimized with the help of density functional theory method (B3LYP) with 6-31+G(d,p), 6-311++G(d,p) basis sets. Stability of the molecule arising from hyperconjugation and charge delocalization is confirmed by the natural bond orbital analysis (NBO). The results show that electron density (ED) in the ?? antibonding orbitals and E(2) energies confirms the occurrence of intramolecular charge transfer (ICT) within the molecule. The assignments of the vibrational spectra have been carried out with the help of normal coordinate analysis following the scaled quantum mechanical force field (SQMFF) methodology. The results of the calculations were applied to simulated spectra of the title compound, which show excellent agreement with observed spectra. The 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by GIAO method. Mulliken population analysis on atomic charges is also calculated. The calculated HOMO and LUMO energy gap shows that charge transfer occurs within the molecule.

Bhavani, K.; Renuga, S.; Muthu, S.; Sankara narayanan, K.

2015-02-01

58

Performic acid oxidation of exo-2-syn-7-bicyclo[2.2.1]hept-5-enediol. 1H and 13C NMR spectroscopic structure elucidation of the reaction products  

NASA Astrophysics Data System (ADS)

Performic acid oxidation of exo-2-syn-7-bicyclo[2.2.1]hept-5-enediol (norborn-5-enediol) gives exo-3-exo-5-syn-7-tricyclo[2.2.1.0 2,6]heptanetriol-(nortricyclenetriol), exo-2-endo-3-endo-5-syn-7-, exo-2-endo-3-endo5-anti-7- and exo-2-endo-3-exo-5-anti-7-bicyclo[2.2.1]heptanetetrols (norbornanetetrols) as reaction products, the relative amounts being 13.7%, 48.1%, 20.2% and 10.4% respectively. The structures of these polyols were elucidated using 1H and 13C NMR spectroscopy including 2D 1H? 1H NOESY, 1H? 1H COSY, 13C? 1H COSY and 13C? 13C INADEQUATE spectra. The reaction mechanism, which consists first of the formation of a norbornyl cation gives, after deprotonation, a triol as an end product. The mechanism leading to the three tetrols includes (1) a Wagner-Meerwein (W-M) rearrangement, (2) a 6,2-hydride shift, (3) another W-M rearrangement and (4) exo attack of the formate anion. The mechanism has been described using the known classical carbocation intermediates. The absence of three theoretically possible reaction products can be explained by intermediates, where the attack of the formate anion on a carbocation is hindered by the vicinal exo hydroxyl group.

Laihia, K.; Kolehmainen, E.; Mänttäri, P.; Ryynänen, R.; Messala-Rannanpiha, M.; Vepsäläinen, J.; Sundelin, J.-P.

1996-05-01

59

Impact of IrRu Oxygen Evolution Reaction Catalysts on Pt Nanostructured Thin Films under Start-Up/Shutdown Cycling  

SciTech Connect

Electron microscopy and X-ray photoelectron spectroscopy (XPS) methods have been utilized to study the role of oxygen evolution reaction (OER) catalysts in mitigating degradation arising from start-up/shutdown events. Pt nanostructured thin films (NSTF) were coated with a Ru0.1Ir0.9 OER catalyst at loadings ranging from 1 to 10 g/cm2 and submitted to 5,000 potential cycles within a membrane electrode assembly. Analysis of the as-deposited catalyst showed that Ir and Ru coating is primarily metallic, and further evidence is provided to support the previously reported interaction between Ru and the perylene-red support. Aberration-corrected scanning transmission electron microscopy and energy dispersive X-ray spectroscopy were used to observe the impact of the OER catalysts on Pt dissolution and migration through the membrane. Elemental mapping showed a high percentage of the Ir catalyst was maintained on the NSTF whisker surfaces following testing. The presence of the OER catalysts greatly reduced the smoothing of the Pt NSTF whiskers, which has been correlated with Pt dissolution and losses in electrochemically active surface area. The dissolution of both Ir and Pt led to the formation of IrPt nanoparticle clusters in the membrane close to the cathode, as well as the formation of a Pt band deeper in the membrane.

Cullen, David A [ORNL; More, Karren Leslie [ORNL; Atanasoska, Liliana [3M, Industrial Mineral Products Division; Atanasoski, Radoslav [3M, Industrial Mineral Products Division

2014-01-01

60

Electronic structure aspects of the spin-forbidden reaction CH3(X 2A2'') + N(4S) --> HCN(X 1?+) + H2(X 1?g+)  

NASA Astrophysics Data System (ADS)

Second order configuration interaction wave functions based on molecular orbitals determined from a state-averaged multiconfigurational self-consistent field procedure are used to investigate the intermediate complex driven model for the spin-forbidden reaction CH3(X 2A2?)+N(4S)?HCN(X 1?+)+H2(X 1?+). The minimum energy crossing point (MECP), the minimum energy point on the surface of intersection connecting the reactant channel, 3A'' potential energy surface, and product channel 1A' potential energy surface, is determined directly, i.e., without a priori characterization of the individual potential energy surfaces. The MECP is found to be 8.2 kcal/mol below of the reactants. The structure at the MECP clearly evinces the incipient formation of a H2 bond. Barrierless paths from the reactants to the intermediate complex-methylnitrene, from the intermediate complex to the MECP, and from the MECP to the products are established. The absence of a barrier on these paths supports the intermediate complex mechanism. Spin-orbit interactions are determined to be ˜30 cm-1 for points on the surface of intersection in the vicinity of the MECP. Spin-orbit interactions and the local potential surface topology at the MECP are used to probe the efficiency of the intersystem crossing using the Landau-Zener model. A reduced dimensionality model is proposed.

Sadygov, Rovshan G.; Yarkony, David R.

1997-10-01

61

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

62

Mechanisms and reaction pathways for simultaneous oxidation of NOx and SO? by ozone determined by in situ IR measurements.  

PubMed

Ozone (O3) oxidation combined with wet scrubbing is a promising method for the simultaneous removal of SO2 and NOx in flue gas. In this study, the O3 oxidation processes of NO and SO2, as well as their coexistence, were investigated using an in situ IR spectrometer. Experimental results showed that the O3 concentration and the reaction temperature played critical roles in the O3 oxidation process of NO. Around 80°C, when inlet molar ratio of O3/NO was less than 1, NO was mainly oxidized to NO2, while when the ratio was greater than 1, NO would be further oxidized to NO3, N2O5, and HNO3. NO3 was the key intermediate product for the formation of N2O5 and HNO3. However, the subsequent reactions of NO3 were temperature dependence. With the increase of reaction temperature above 100°C, the concentration of NO2 increased whereas the concentrations of N2O5 and HNO3 decreased. The oxidation of SO2 by O3 was negligible and SO2 had little influence on the oxidation of NO in the simultaneous oxidation of NO and SO2. Finally, based on the in situ IR results, the oxidation mechanism is discussed and the reaction pathways are proposed. PMID:24801895

Sun, Chenglang; Zhao, Nan; Zhuang, Zhuokai; Wang, Haiqiang; Liu, Yue; Weng, Xiaole; Wu, Zhongbiao

2014-06-15

63

An FT-IR study on Diels Alder reactions catalysed by heteropoly acid containing sol gel silica  

NASA Astrophysics Data System (ADS)

Following the general trend of using heterogeneous catalysts whenever possible, the replacement of traditional homogeneous Lewis acid catalysts for the Diels-Alder reaction is currently considered in the literature. In this contribution, we report the successful application of sol-gel derived tungstophosphoric acid-silica composites as catalysts in the reaction of 1,3-cyclohexadiene and 2-propenal. The reaction was monitored by in situ FT-IR spectroscopy following the changes in the fine structure of the ?(C?O) band. The catalytic activity of the sol-gel immobilised heteropoly acids seems to be comparable with that of more conventional sol-gel silica-aluminas and their selectivity is even better because Broensted acid sites are destroyed upon calcination of the dry gel.

Kukovecz, Á.; Kónya, Z.; Kiricsi, I.

2001-05-01

64

Efficient, Green, Solvent-Free Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones via Biginelli Reaction Catalyzed by Cu(NO3)2·3H2O  

Microsoft Academic Search

The synthesis of 3,4-dihydropyrimidin-2-(1H)-ones derivatives via a three-component Biginelli reaction using copper nitrate as a catalyst under solventless conditions is reported, providing a green, rapid, efficient, and convenient method for the preparation of Biginelli compounds in good yields.

Dong-Chao Wang; Hai-Ming Guo; Gui-Rong Qu

2010-01-01

65

Improved $^{192,194,195,196}$Pt($n,?$) and $^{192}$Ir($n,?$) astrophysical reactions rates  

E-print Network

$^{192}$Pt is produced solely by the slow neutron capture (\\textit{s}) nucleosynthesis process and hence an accurate ($n$,$\\gamma $) reaction rate for this nuclide would allow its use as an important calibration point near the termination of the \\textit{s}-process nucleosynthesis flow. For this reason, we have measured neutron capture and total cross sections for $% ^{192,194,195,196,nat}$Pt in the energy range from 10 eV to several hundred keV at the Oak Ridge Electron Linear Accelerator. Measurements on the other Pt isotopes were, in part, necessitated by the fact that only a relatively small $^{192}$Pt sample of modest enrichment was available. Astrophysical $% ^{192,194,195,196}$Pt($n,\\gamma $) reaction rates, accurate to approximately 3%--5 %, were calculated from these data. No accurate reaction rates have been published previously for any of these isotopes. At \\textit{s}-process temperatures, previously recommended rates are larger (by as much as 35%) and have significantly different shapes as functions of temperature, than our new rates. We used our new Pt results, together with $^{191,193}$Ir(n,$% \\gamma $) data, to calibrate nuclear statistical model calculations and hence obtain an improved rate for the unmeasured \\textit{s}-process branching-point isotope $^{192}$Ir.

P. E. Koehler; K. H. Guber

2013-09-03

66

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

67

Synthesis of 5-nitro-3,4-dihydropyrimidin-2(1 H )-ones catalyzed by metal salts. Retro-Henry reaction with formation of N,N? -disubstituted ureas  

Microsoft Academic Search

Three-component condensation of ?-nitroacetophenone with aromatic aldehydes and urea in the presence of iron(III), cobalt(II),\\u000a nickel(II), and copper(II) salts as catalyst led to the formation of 4,6-diaryl-5-nitro-3,4-dihydropyrimidin-2(1H)-ones and N-benzoyl-N?-(1-aryl-2-nitroethyl)ureas. The latter were formed as a result of retro-nitroaldol (retro-Henry) reaction of intermediate\\u000a 4,6-diaryl-6-hydroxy-5-nitro-3,4,5,6-tetra-hydropyrimidin-2(1H)-ones.

V. F. Sedova; V. P. Krivopalov; O. P. Shkurko

2007-01-01

68

Simultaneous IR and time-resolved X-ray diffraction measurements for studying self-sustained reactions.  

PubMed

Self-propagating high-temperature synthesis provides an attractive practical method for producing advanced materials such as ceramics, composites and intermetallics. This kind of reaction has been investigated in situ using time-resolved X-ray diffraction, with an X-ray synchrotron beam (D43 beamline, LURE, Orsay) coupled to simultaneous IR thermography to study structural transformations and thermal evolution. With short acquisition times (30 ms per pattern) it has been possible to observe several steps before obtaining compounds. Two different compound formations have been described: (i) the different steps of reaction, aluminium melting, subsequent temperature increase and fast reaction between Al and Ni at such temperatures that only Ni and AlNi are solid and all other compositions are liquid and well identified; (ii) the formation of FeAl. Here, a portion of the iron seems to transform into its allotropic phase and this transition stabilizes the reaction temperature at approximately 1173 K. In addition, the aluminium melting during the reaction explains why the nanostructure induced by the mechanical activation is maintained in the end product. PMID:16609169

Bernard, F; Gaffet, E; Gramond, M; Gailhanou, M; Gachon, J C

2000-01-01

69

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

SciTech Connect

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

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

2007-07-15

70

Adsorption and oxidation of formaldehyde on a polycrystalline Pt film electrode: An in situ IR spectroscopy search for adsorbed reaction intermediates.  

PubMed

As part of a mechanistic study of the electrooxidation of C1 molecules we have systematically investigated the dissociative adsorption/oxidation of formaldehyde on a polycrystalline Pt film electrode under experimental conditions optimizing the chance for detecting weakly adsorbed reaction intermediates. Employing in situ IR spectroscopy in an attenuated total reflection configuration (ATR-FTIRS) with p-polarized IR radiation to further improve the signal-to-noise ratio, and using low reaction temperatures (3 °C) and deuterium substitution to slow down the reaction kinetics and to stabilize weakly adsorbed reaction intermediates, we could detect an IR absorption band at 1660 cm(-1) characteristic for adsorbed formyl intermediates. This assignment is supported by an isotope shift in wave number. Effects of temperature, potential and deuterium substitution on the formation and disappearance of different adsorbed species (COad, adsorbed formate, adsorbed formyl), are monitored and quantified. Consequences on the mechanism for dissociative adsorption and oxidation of formaldehyde are discussed. PMID:24991512

Jusys, Zenonas; Behm, R Jürgen

2014-01-01

71

Adsorption and oxidation of formaldehyde on a polycrystalline Pt film electrode: An in situ IR spectroscopy search for adsorbed reaction intermediates  

PubMed Central

Summary As part of a mechanistic study of the electrooxidation of C1 molecules we have systematically investigated the dissociative adsorption/oxidation of formaldehyde on a polycrystalline Pt film electrode under experimental conditions optimizing the chance for detecting weakly adsorbed reaction intermediates. Employing in situ IR spectroscopy in an attenuated total reflection configuration (ATR-FTIRS) with p-polarized IR radiation to further improve the signal-to-noise ratio, and using low reaction temperatures (3 °C) and deuterium substitution to slow down the reaction kinetics and to stabilize weakly adsorbed reaction intermediates, we could detect an IR absorption band at 1660 cm?1 characteristic for adsorbed formyl intermediates. This assignment is supported by an isotope shift in wave number. Effects of temperature, potential and deuterium substitution on the formation and disappearance of different adsorbed species (COad, adsorbed formate, adsorbed formyl), are monitored and quantified. Consequences on the mechanism for dissociative adsorption and oxidation of formaldehyde are discussed. PMID:24991512

Behm, R Jürgen

2014-01-01

72

4240 J. Am. Chem. SOC.1982, 104, 4240-4242 After 1 h at room temperature, the reaction was concentrated in vacuo,  

E-print Network

L of glacial acetic acid-water (60:40,v/v) was stirred at room temperature for 5 h. Re- moval of the solventL of ether and filtered. The solvent was removed under reduced pressure, and the residue was chromatographed, J = 7.5Hz), 1.00(s, 1 H). Recrystallization from acetone-hexane provided analytically pure dl

Jones, William D.

73

Synthesis of 3,4-dihydropyridin-2(1H)-ones and 3,4-dihydro-2H-pyrans via Four-component reactions of aromatic aldehydes, cyclic 1,3-carbonyls, arylamines, and dimethyl acetylenedicarboxylate.  

PubMed

A protocol has been developed for the efficient synthesis of structurally diverse 3,4-dihydropyridin-2(1H)-ones and 3,4-dihydro-2H-pyrans via four-component reactions of arylamines, acetylenedicarboxylate, aromatic aldehydes and cyclic 1,3-diketones. The selective formation of the very different pyridinone or pyran derivatives depends on the structure of cyclic 1,3-diketone. The key steps are proposed to involve Michael addition of the enamino ester formed in situ from the reaction of arylamine with dimethyl acetylenedicarboxylate to arylidine cyclic 1,3-diketones. PMID:21568339

Sun, Jing; Xia, Er-Yan; Wu, Qun; Yan, Chao-Guo

2011-07-11

74

6Amino5-cyano-1H,4H-pyrazolo[3,4-b]pyrans  

Microsoft Academic Search

The reaction of 3-methyl-1-phenyl-5-pyrazolene with arylideneamino nitriles in alcohol leads to the formation of 3-methyl-4(1-aryl-2,2-dicyanoethyl)-5-pyrazolones, which are readily cyclized in the presence of bases to the corresponding 6-amino-5-cyano-3-methyl-4-aryl- 1H,4H-pyrazolo[3,4-b]pyrans. The structures of the intermediate and final products were confirmed by the IR, UV, PMR, and mass spectra.

L. G. Sharanina; V. K. Promonenkov; V. P. Marshtupa; A. V. Pashchenko; V. V. Puzanova; Yu. A. Sharanin; N. A. Klyuev; L. F. Gusev; A. P. Gnatusina

1982-01-01

75

A multimetallic piano-stool Ir-Sn3 catalyst for nucleophilic substitution reaction of ?-hydroxy lactams through N-acyliminium ions.  

PubMed

A multimetallic piano-stool complex [Cp*Ir(SnCl(3))(2){SnCl(2)(H(2)O)(2)}] (1) having Ir-Sn(3) motif has been synthesized from [Cp*IrCl(2)](2) and SnCl(2). The multimetallic complex catalytically promotes the nucleophilic substitution reaction (here after ?-amidoalkylation reaction) of ?-hydroxylactams generated from phthalimidals to obtain decorated isoindolinones in excellent yields. Succinamidals, however, lead to the substituted pyrrolidinones (thermodynamic control product) via S(N)1-type path as well as eliminated pyrrolinones (kinetic control product) via an E1-type path, depending on the reaction parameters. A straightforward application of this methodology is to synthesize benzo-fused indolizidine alkaloid mimics. PMID:22364643

Maity, Arnab Kumar; Roy, Sujit

2012-03-16

76

Time-Resolved O3 Chemical Chain Reaction Kinetics Via High-Resolution IR Laser Absorption Methods  

NASA Technical Reports Server (NTRS)

Excimer laser photolysis in combination with time-resolved IR laser absorption detection of OH radicals has been used to study O3/OH(v = 0)/HO2 chain reaction kinetics at 298 K, (i.e.,(k(sub 1) is OH + 03 yields H02 + 02 and (k(sub 2) is H02 + 03 yields OH + 202). From time-resolved detection of OH radicals with high-resolution near IR laser absorption methods, the chain induction kinetics have been measured at up to an order of magnitude higher ozone concentrations ([03] less than or equal to 10(exp 17) molecules/cu cm) than accessible in previous studies. This greater dynamic range permits the full evolution of the chain induction, propagation, and termination process to be temporally isolated and measured in real time. An exact solution for time-dependent OH evolution under pseudo- first-order chain reaction conditions is presented, which correctly predicts new kinetic signatures not included in previous OH + 03 kinetic analyses. Specifically, the solutions predict an initial exponential loss (chain "induction") of the OH radical to a steady-state level ([OH](sub ss)), with this fast initial decay determined by the sum of both chain rate constants, k(sub ind) = k(sub 1) + k(sub 2). By monitoring the chain induction feature, this sum of the rate constants is determined to be k(sub ind) = 8.4(8) x 10(exp -14) cu cm/molecule/s for room temperature reagents. This is significantly higher than the values currently recommended for use in atmospheric models, but in excellent agreement with previous results from Ravishankara et al.

Kulcke, Axel; Blackmon, Brad; Chapman, William B.; Kim, In Koo; Nesbitt, David J.

1998-01-01

77

Bismuth Subnitrate Catalyzed Efficient Synthesis of 3,4?Dihydropyrimidin?2(1H)?Ones: An Improved Protocol for the Biginelli Reaction  

Microsoft Academic Search

An efficient synthesis of 3,4?dihydropyrimidinones (DHPMs) using bismuth subnitrate as the catalyst for the first time from an aldehyde, ??ketoester, and urea in acetonitrile is described. This new method consistently has the advantage of excellent yields (88–96%) and short reaction times (1.5–4 h) than do classical Biginelli reaction conditions.

Y. Thirupathi Reddy; B. Rajitha; P. Narsimha Reddy; B. Sunil Kumar; V. P. Rao G

2004-01-01

78

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

PubMed

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

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

2009-02-28

79

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

PubMed Central

An environmentally benign green protocol for the synthesis of 5-unsubstituted 3,4-dihydropyrimidin-2(1H)-ones using Amberlyst 15 DRY as a recyclable catalyst has been developed. The use of resinous, nontoxic, thermally stable, and inexpensive Amberlyst 15 DRY, as a recyclable heterogeneous catalyst, makes the process simple with negligible chemical waste. Among the various solid acid catalysts Amberlyst 15 DRY was found to be the most efficient catalyst with regard to reaction time, yield, and ease of work-up procedure. PMID:24052845

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

2012-01-01

80

Comparative study for separation of atmospheric humic-like substance (HULIS) by ENVI-18, HLB, XAD-8 and DEAE sorbents: elemental composition, FT-IR, 1H NMR and off-line thermochemolysis with tetramethylammonium hydroxide (TMAH).  

PubMed

Humic-like substances (HULIS) are significant constituents of aerosols, and the isolation and characterization of HULIS by solid-phase extraction methods are dependent on the sorbents used. In this study, we used the following five methods: ENVI-18, HLB-M, HLB-N, XAD-8 and DEAE, to isolate atmospheric HULIS at an urban site. Then we conducted a comparative investigation of the HULIS chemical characteristics by means of elemental analysis, Fourier transform infrared spectroscopy, (1)H nuclear magnetic resonance spectroscopy and off-line thermochemolysis with tetramethylammonium hydroxide. The results indicate that HULIS isolated using different methods show many similarities in chemical composition and structure. Some differences were however also observed between the five isolated HULIS: HULISHLB-M contains a relatively high content of OCH group, compared to HULISENVI-18 and HULISXAD-8; HULISXAD-8 contains a relatively high content of hydrophobic and aromatic components, compared to HULISENVI-18 and HULISHLB-M; HULISDEAE contains the highest content of aromatic functional groups, as inferred by (1)H NMR spectra, but a great amount of salts generally present in the HULISDEAE and thereby limited the choices for characterizing the materials (i.e., elemental analysis and TMAH thermochemolysis); HULISHLB-N has relatively high levels of H and N, a high N/C atomic ratio, and includes N-containing functional groups, which suggests that it has been altered by 2% ammonia introduced in the eluents. In summary, we found that ENVI-18, HLB-M, and XAD-8 are preferable methods for isolation and characterization of HULIS in atmospheric aerosols. These results also suggest that caution is required when applying DEAE and HLB-N isolating methods for characterizing atmospheric HULIS. PMID:23773442

Fan, Xingjun; Song, Jianzhong; Peng, Ping'an

2013-11-01

81

/sup 194/ /sup 196/ /sup 198/Pt(t,. cap alpha. )/sup 193/ /sup 195/ /sup 197/Ir reactions with polarized tritons. [17 MeV  

SciTech Connect

The /sup 194/ /sup 196/ /sup 198/Pt(t vector, ..cap alpha..)/sup 193/ /sup 195/ /sup 197/Ir reactions were measured. Angular distributions of cross sections and analyzing powers for levels up to approx. 2.5 MeV in each residual nuclide were obtained, and comparisons with DWBA predictions allowed spins, parities, and pickup spectroscopic strengths to be determined. The results are being analyzed with the aim of testing the existence of supersymmmetric structures in nature. 2 figures.

Cizewski, J.A.; Flynn, E.R.; Sunier, J.W.; Brown, R.E.; Burke, D.G.

1980-01-01

82

Study of the 192Os(d,2n) reaction for production of the therapeutic radionuclide 192Ir in no-carrier added form  

Microsoft Academic Search

In the frame of an IAEA coordinated research project (CRP) on nuclear data for production of therapeutic radionuclides, the production of 192Ir via deuteron-induced reactions on enriched 192Os was investigated up to 21MeV deuteron energy. Cross sections were measured using the conventional stacked-foil irradiation technique and high-resolution gamma-ray spectroscopy of the activation products. No earlier experimental data were found in

F. Tárkányi; A. Hermanne; S. Takács; K. Hilgers; S. F. Kovalev; A. V. Ignatyuk; S. M. Qaim

2007-01-01

83

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

Microsoft Academic Search

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

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

2011-01-01

84

FT-IR, NBO, HOMO-LUMO, MEP analysis and molecular docking study of 1-[3-(4-Fluorophenyl)-5-phenyl-4,5-dihydro-1H-pyrazol-1-yl]ethanone  

NASA Astrophysics Data System (ADS)

The optimized molecular structure, vibrational frequencies, corresponding vibrational assignments of 1-[3-(4-fluorophenyl)-5-phenyl-4,5-dihydro-1H-pyrazol-1-yl]ethanone have been investigated experimentally and theoretically. The geometrical parameters are in agreement with XRD data. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis. The HOMO and LUMO analysis is used to determine the charge transfer within the molecule. From the MEP it is evident that the negative charge covers the carbonyl group and the positive region is over the remaining groups. The more electronegativity in the carbonyl group makes it the most reactive part in the molecule. First hyperpolarizability is calculated in order to find its role in nonlinear optics. From the molecular docking studies, it is evident that the fluorine atom attached to benzene ring and ethanone attached to the pyrazoline ring are crucial for binding and the compound might exhibit inhibitory activity against TPII and may act as anti-neoplastic agent.

Mary, Y. Sheena; Panicker, C. Yohannan; Sapnakumari, M.; Narayana, B.; Sarojini, B. K.; Al-Saadi, Abdulaziz A.; Van Alsenoy, Christian; War, Javeed Ahmad

2015-02-01

85

Quantum mechanical study of the structure and spectroscopic (FT-IR, FT-Raman, 13C, and 1H) and HOMO-LUMO analysis of 2,4-dimethoxy benzaldehyde (DMBA) and 4-methoxy-3-methyl benzaldehyde (MMBA)  

NASA Astrophysics Data System (ADS)

The present communication is aimed at comparing the molecular structural properties, vibrational and energetic data of 2,4-dimethoxy benzaldehyde and for 4-methoxy-3-methyl benzaldehyde, due to their commercial importance. The ground state properties of the title molecules have been calculated employing DFT/B3LYP level of theory using the 6-31G (d) basis set. In order to obtain a complete description of molecular dynamics, vibrational wavenumber calculation along with the normal mode analysis, have been carried out at the DFT level. The calculated spectra of both the molecules agree well with the experimental data. The 1H and 13C NMR spectra have been simulated using the gauge independent atomic orbital (GIAO) method. The electronic properties, such as HOMO, LUMO energies, absolute electronegativity X and absolute hardness ? were performed by DFT approach. The first order hyperpolarizability (?o) of these novel molecular system and related properties (?, ?o and ??) of DMBA and MMBA are calculated using DFT/6-31G (d) method on the finite-field approach.

KrishnaKumar, V.; Barathi, D.; Mathammal, R.

2013-03-01

86

Measurements of the neutron electric to magnetic form factor ratio GEn/GMn via the ^2H(\\vec{e},e'\\vec{n})^1H reaction to Q^2 = 1.45 (GeV/c)^2  

E-print Network

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

Jefferson Laboratory E93-038 Collaboration; :; B. Plaster; A. Yu. Semenov

2005-11-13

87

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

88

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

PubMed

The FT-IR, FT-Raman and NMR ((1)H and (13)C) spectra of benzenesulfonic acid as well as lithium, sodium, potassium, rubidium and caesium benzenesulfonates were registered, assigned and compared. The molecular structures of ligand and alkali metal salts were discussed. On the basis of quantum mechanical calculations in MP2/6-311++G(d,p) and B3LYP/6-311++G(d,p) levels the geometric parameters, infrared spectra, NMR spectra, the magnetic and geometric aromaticity indices for acid and alkali metal benzenesulfonates and benzoates were obtained. The effect of alkali metal ions on the electronic charge distribution of benzenesulfonic acid was studied and compared with the alkali metal benzoates and benzoic acid. PMID:22406243

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

2013-01-01

89

Mid-IR band gap engineering of CdxPb1-xS nanocrystals by mechanochemical reaction  

NASA Astrophysics Data System (ADS)

Composition-tunable ternary CdxPb1-xS nanocrystals (NCs) are very important materials for remote sensing and detecting in the infrared (IR) wavelength region. They are, however, almost exclusively prepared by wet chemical routes which lead to surface-capped nanoparticles. The surface capping molecules could move their absorption peaks from mid-IR to near IR wavelength region. However, surface clean CdxPb1-xS nanocrystals (NCs) would demonstrate intrinsic optical spectrum in the mid-IR region. Herein, we present a physical mechanical alloying (MA) process being applied to prepare tens of grams of surface clean CdxPb1-xS nanocrystals within the composition range of x = 0.0 to 0.4. The average particle size is smaller than 9 nm. The as-milled nanocrystals are chemically homogenous. The CdxPb1-xS nanocrystals show a continuous lattice contraction with Cd content. There is an exponential indirect band gap-composition relationship. This MA method shows the ability to continuously and precisely tune the band gap energies of ternary CdxPb1-xS semiconductor nanocrystals from mid-IR region (2638 nm) to NIR wavelength region (1240 nm) through chemical composition.

Tan, Guo-Long; Liu, Limin; Wu, Weibing

2014-06-01

90

Electrocatalytic activity of Ru{sub x}Ir{sub 1{minus}x}O{sub 2} thin layers for the hydrogen evolution reaction  

SciTech Connect

The catalytic activity of mixed oxide Ru{sub x}Ir{sub 1{minus}x}O{sub 2} layers have been studied for the hydrogen evolution reaction in 1M H{sub 2}SO{sub 4}. All the layers exhibit an activation phenomenon that yield to an increase of the current density. The occurrence of this phenomenon is driven by the potential of the electrode and the activation is lost when the electrode is withdrawn from the electrolytic solution. The activity of the various electrodes was measured with respect to the composition of the film (x in Ru{sub x}Ir{sub 1{minus}x}O{sub 2}). It was found that the current density is not a linear function of the Ru bulk nominal concentration. This effect is due to the surface enrichment of the electrode with iridium.

Blouin, M.; Guay, D. [INRS, Varennes, Quebec (Canada). Energie et Materiaux

1994-12-31

91

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

92

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

93

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

94

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

95

Time-resolved IR spectroscopy in liquid rare gases: Direct rate measurement of an intermolecular alkane CH oxidative addition reaction  

Microsoft Academic Search

Since the first demonstration of the intermolecular oxidative addition of alkane C-H bonds to transition-metal centers, there have been many studies of the mechanism of this reaction. While these studies have illuminated many aspects of the C-H activation process, they do not provide direct information about the reactive intermediates or the potential energy surface for the elementary insertion reaction. Flash

B. H. Weiller; E. P. Wasserman; R. G. Bergman; C. B. Moore; G. C. Pimentel

1989-01-01

96

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.

97

Measurement of the 187Re(? ,n )190Ir reaction cross section at sub-Coulomb energies using the Cologne Clover Counting Setup  

NASA Astrophysics Data System (ADS)

Background: Uncertainties in adopted models of particle+nucleu s optical-model potentials directly influence the accuracy in the theoretical predictions of reaction rates as they are needed for reaction-network calculations in, for instance, ? -process nucleosynthesis. The improvement of the ? +nucleu s optical-model potential is hampered by the lack of experimental data at astrophysically relevant energies especially for heavier nuclei. Purpose: Measuring the 187Re(? ,n )190Ir reaction cross section at sub-Coulomb energies extends the scarce experimental data available in this mass region and helps understanding the energy dependence of the imaginary part of the ? +nucleus optical-model potential at low energies. Method: Applying the activation method, after the irradiation of natural rhenium targets with ? -particle energies of 12.4 to 14.1 MeV, the reaction yield and thus the reaction cross section were determined via ? -ray spectroscopy by using the Cologne Clover Counting Setup and the method of ? ? coincidences. Results: Cross-section values at five energies close to the astrophysically relevant energy region were measured. Statistical model calculations revealed discrepancies between the experimental values and predictions based on widely used ? +nucleus optical-model potentials. However, an excellent reproduction of the measured cross-section values could be achieved from calculations based on the so-called Sauerwein-Rauscher ? +nucleus optical-model potential. Conclusion: The results obtained indicate that the energy dependence of the imaginary part of the ? +nucleus optical-model potential can be described by an exponential decrease. Successful reproductions of measured cross sections at low energies for ? -induced reactions in the mass range 141 ?A ?187 confirm the global character of the Sauerwein-Rauscher potential.

Scholz, P.; Endres, A.; Hennig, A.; Netterdon, L.; Becker, H. W.; Endres, J.; Mayer, J.; Giesen, U.; Rogalla, D.; Schlüter, F.; Pickstone, S. G.; Zell, K. O.; Zilges, A.

2014-12-01

98

Measurement of the 187Re(?,n)190Ir reaction cross section at sub-Coulomb energies using the Cologne Clover Counting Setup  

E-print Network

Uncertainties in adopted models of particle+nucleus optical-model potentials directly influence the accuracy in the theoretical predictions of reaction rates as they are needed for reaction-network calculations in, for instance, {\\gamma}-process nucleosynthesis. The improvement of the {\\alpha}+nucleus optical-model potential is hampered by the lack of experimental data at astrophysically relevant energies especially for heavier nuclei. Measuring the Re187({\\alpha},n)Ir190 reaction cross section at sub-Coulomb energies extends the scarce experimental data available in this mass region and helps understanding the energy dependence of the imaginary part of the {\\alpha}+nucleus optical-model potential at low energies. Applying the activation method, after the irradiation of natural rhenium targets with {\\alpha}-particle energies of 12.4 to 14.1 MeV, the reaction yield and thus the reaction cross section were determined via {\\gamma}-ray spectroscopy by using the Cologne Clover Counting Setup and the method of {\\gamma}{\\gamma} coincidences. Cross-section values at five energies close to the astrophysically relevant energy region were measured. Statistical model calculations revealed discrepancies between the experimental values and predictions based on widely used {\\alpha}+nucleus optical-model potentials. However, an excellent reproduction of the measured cross-section values could be achieved from calculations based on the so-called Sauerwein-Rauscher {\\alpha}+nucleus optical-model potential. The results obtained indicate that the energy dependence of the imaginary part of the {\\alpha}+nucleus optical-model potential can be described by an exponential decrease. Successful reproductions of measured cross sections at low energies for {\\alpha}-induced reactions in the mass range 141{\\leq}A{\\leq}187 confirm the global character of the Sauerwein-Rauscher potential.

P. Scholz; A. Endres; A. Hennig; L. Netterdon; H. W. Becker; J. Endres; J. Mayer; U. Giesen; D. Rogalla; F. Schlüter; S. G. Pickstone; K. O. Zell; A. Zilges

2015-01-07

99

FT-IR product study of the reactions of NO3 radicals with ortho-, meta-, and para-cresol.  

PubMed

Product analyses of the NO3 radical-initiated oxidation of ortho-, meta-, and para-cresol have been performed in large-volume chamber systems at the University of Wuppertal (1080 L quartz glass reactor: QUAREC) and the European Photoreactor (EUPHORE), Valencia, Spain. The reaction of O3 with NO2 was used for the in situ generation of NO3 radicals in both QUAREC and EUPHORE. In the QUAREC experiments the gas-phase reaction of ortho-cresol isomer with NO3 yielded (11.5 ± 0.8) % 6-methyl-2-nitrophenol (6M2NP), (4.4 ± 0.3) % methyl-1,4-benzoquinone (MQUIN) and (77.2 ± 6.3) % HNO3. The reaction of NO3 radicals with meta-cresol yielded (21.2 ± 1.4) % 3-methyl-2-nitrophenol (3M2NP), (22.8 ± 1.8) % 3-methyl-4-nitrophenol (3M4NP), (23.5 ± 1.8) % 5-methyl-2-nitrophenol (5M2NP), (4.2 ± 0.7) % MQUIN and (72.3 ± 6.4) % HNO3. In the reaction of NO3 radicals with para-cresol, 4-methyl-2-nitrophenol (4M2NP) and HNO3 were identified as products with yields of (41.3 ± 3.7) % and (85.0 ± 10.2) %, respectively. In the EUPHORE chamber not all products were formed at levels above the detection limit, however, in cases where detection was possible similar product yields were observed. The product formation yields determined in both chambers are compared with available literature data and a gas-phase mechanism is proposed to explain the formation of the products observed from the reaction of NO3 and with cresol isomers. PMID:23751015

Olariu, R I; Barnes, I; Bejan, I; Arsene, C; Vione, D; Klotz, B; Becker, K H

2013-07-16

100

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

101

Insights into the reaction mechanism of CO oxidative coupling to dimethyl oxalate over palladium: a combined DFT and IR study.  

PubMed

Oxidative coupling of toxic pollutant CO to form the platform raw chemical material dimethyl oxalate (DMO) has been industrialized however the catalytic mechanism has been unknown so far. The reaction mechanism of CO oxidative coupling to form DMO on a Pd(111) surface has been investigated using density functional theory (DFT) and in situ diffuse reflectance infrared (DRIR) spectroscopy. DFT calculations and in situ DRIRS measurements indicate that two co-adsorbed intermediates COOMe and OCCO, initiate the reaction. C-C coupling occurs earlier due to a low coupling barrier and small steric hindrance. The results also suggest that Pd(111) is selective towards DMO over DMC, and that CO pre-adsorption and CO in excess effectively enhance the yield of DMO. The microscopic elucidation of this important reaction suggests improvements in coal-to-EG (CTEG) production which can be applied in practice to effectively enhance the yield and reduce the cost. The results may help with further fine-tuning and designing of high-efficient noble metal catalysts. PMID:25759866

Li, Qiaohong; Zhou, Zhangfeng; Chen, Ruiping; Sun, Baozhen; Qiao, Luyang; Yao, Yuangen; Wu, Kechen

2015-04-14

102

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

103

Jul-Aug 2006 Synthesis and Biological Activities of cis and trans 5Amino3-((6-chloro-3- pyridyl)methyl)amino-1-(5,5-dimethyl-2-oxo-4-substitutedphenyl- 1,3,2-dioxaphosphinan-2-yl)-4-cyano(ethoxycarbonyl)-1H-pyrazoles  

Microsoft Academic Search

A series of novel title compounds have been designed and synthesized by a multi-step reaction, the stereochemistry of the reaction was investigated, the structures of all compounds prepared have been confirmed by 1 H NMR, IR, EI-MS spectroscopy and elemental analysis. The crystal structures of cis 6b and trans 6b were determined by single crystal X-ray diffraction. The results of

Zai-Gang Luo; De-Qing Shi

2006-01-01

104

Formation of 5- and 6-methyl-1H-indene (C10H10) via the reactions of the para-tolyl radical (C6H4CH3) with allene (H2CCCH2) and methylacetylene (HCCCH3) under single collision conditions.  

PubMed

The reactions of the p-tolyl radical with allene-d4 and methylacetylene-d4 as well as of the p-tolyl-d7 radical with methylacetylene-d1 and methylacetylene-d3 were carried out under single collision conditions at collision energies of 44-48 kJ mol(-1) and combined with electronic structure and statistical (RRKM) calculations. Our experimental results indicated that the reactions of p-tolyl with allene-d4 and methylacetylene-d4 proceeded via indirect reaction dynamics with laboratory angular distributions spanning about 20° in the scattering plane. As a result, the center-of-mass translational energy distribution determined a reaction exoergicity of 149 ± 28 kJ mol(-1) and exhibited a pronounced maximum at around 20 to 30 kJ mol(-1). In addition, the center-of-mass angular flux distribution T(?) depicted a forward-backward symmetry and indicated geometric constraints upon the decomposing complex(es). Combining with calculations, these results propose that the bicyclic polycyclic aromatic hydrocarbons, 6-methyl-1H-indene () and 5-methyl-1H-indene (), are formed under single collision conditions at fractions of at least 85% in both reaction systems. For the p-tolyl-methylacetylene system, experiments with partially deuterated reactants also reveal the formation of a third isomer (1-methyl-4-(1-propynyl)benzene) at levels of 5-10%, highlighting the importance in conducting reactions with partially deuterated reactants to elucidate the underlying reaction pathways comprehensively. PMID:25806373

Yang, Tao; Parker, Dorian S N; Dangi, Beni B; Kaiser, Ralf I; Mebel, Alexander M

2015-04-01

105

A novel one-pot three-(in situ five-)component condensation reaction: an unexpected approach for the synthesis of tetrahydro-2,4-dioxo-1H-benzo[b][1,5]diazepine-3-yl-2-methylpropanamide derivatives.  

PubMed

A novel and efficient method has been developed for the synthesis of tetrahydro-2,4-dioxo-1H-benzo[b][1,5]diazepine-3-yl-2-methylpropanamide derivatives using an aromatic diamine, Meldrum's acid, and an isocyanide in CH(2)Cl(2) at ambient temperature in high yields without using any catalyst or activation. The procedure provides an alternative method for the synthesis of benzo[b][1,5]diazepine derivatives. These compounds have closely related ring systems such as triflubazam, clobazam, and 1,5-benzodiazepines, which have a broad spectrum of biological activities. PMID:19719182

Shaabani, Ahmad; Rezayan, Ali Hossein; Keshipour, Sajjad; Sarvary, Afshin; Ng, Seik Weng

2009-08-01

106

Tetrahydroindeno[1',2':4,5]pyrrolo[1,2-a]imidazol-5(1H)-ones as Novel Neonicotinoid Insecticides: Reaction Selectivity and Substituent Effects on the Activity Level.  

PubMed

Tetraheterocyclic tetrahydroindeno[1',2':4,5]pyrrolo[1,2-a]imidazol-5(1H)-one derivatives as novel neonicotinoid candidates were designed and prepared by selective etherification, chlorination and esterification of ninhydrin-heterocyclic ketene aminals adducts. Some of the designed compounds showed excellent insecticidal activity against cowpea aphids (Aphis craccivora), brown planthopper (Nilaparvata lugens), and armyworm (Mythimna separata). In particular, the activity against armyworm (Mythimna separata) improved a lot in contrast with that of imidacloprid and cycloxaprid. The research here provides a novel neonicotinoid chemotype for further development. PMID:25611859

Chen, Nanyang; Meng, Xiaoqing; Zhu, Fengjuan; Cheng, Jiagao; Shao, Xusheng; Li, Zhong

2015-02-11

107

The rotational distribution in the mercury hydride molecules (X 2Sigma + 1/2;vscript=0) produced in the reactions Hg(6 3P1)+H2, HD, or D2  

NASA Astrophysics Data System (ADS)

Initial rotational distributions of the vibrationless HgH or HgD molecules produced in the exoergic reactions of Hg (3P1) with H2, D2, and HD have been determined. No isotope effects have been observed. In the case of the reaction with HD the ratio [HgH(v`=0)]/[HgD (v`=0)] as well as the summed over all v` ratio [HgH]/[HgD] have been measured.

Bras, N.; Butaux, J.; Jeannet, J. C.; Perrin, D.

1986-07-01

108

Time-dependent wave packet and quasiclassical trajectory study of the C(3P)+OH(X 2?)-->CO(X 1?+)+H(2S) reaction at the state-to-state level  

NASA Astrophysics Data System (ADS)

The first calculations of state-to-state reaction probabilities and product state-resolved integral cross sections at selected collision energies (0.05, 0.1, 0.5, and 1.0 eV) for the title reaction on the ab initio potential energy surface of [Zanchet et al. J. Phys. Chem. A 110, 12017 (2006)] with the OH reagent in selected rovibrational states (v =0-2, j=0-5) have been carried out by means of the real wave packet (RWP) and quasiclassical trajectory (QCT) methods. State-selected total reaction probabilities have been calculated for total angular momentum J =0 in a broad range of collision energies. Integral cross sections and state-specific rate coefficients have been obtained from the corresponding J =0 RWP reaction probabilities for initially selected rovibrational states by means of a capture model. The calculated RWP and QCT state-selected rate coefficients are practically temperature independent. Both RWP and QCT reaction probabilities, integral cross sections, and rate coefficients are almost independent of the initial rotational excitation. The RWP results are found to be in an overall good agreement with the corresponding QCT results. The present results have been compared with earlier wave packet calculations carried out on the same potential energy surface.

Bulut, Niyazi; Zanchet, Alexandre; Honvault, Pascal; Bussery-Honvault, Béatrice; Bañares, Luis

2009-05-01

109

Unexpected reactions of 2,5-dimethylthiopene (2,5-Me{sub 2}t) in Cp{sup *}Ir({eta}{sup 5}-2,5-Me{sub 2}T){sup 2+}, Cp{sup *}Ir({eta}{sup 4}-2,5-Me{sub 2}T), and Cp{sup *}Ir(C,S-2,5-Me{sub 2}T) with cobaltocene  

SciTech Connect

The reaction of Cp{sup *}Ir({eta}{sup 5}-2,5-Me{sub 2}T){sup 2+} (1) (Cp{sup *} = {eta}{sup 5}-C{sub 5}Me{sub 5}) with the reducing agent Cp{sub 2}Co yields Cp{sup *}Ir({eta}{sup 4}-2,5-Me{sub 2}T) (2) and Cp{sup *}Ir(C,S-2,5-Me{sub 2}T) (3), as well as the unexpected Cp{sup *}Ir({eta}{sup 4}-2,5-Me{sub 2}T{center_dot}C{sub 5}H{sub 4}) (4), which can also be prepared by reacting 1 with Cp{sup -}. An X-ray diffraction study of 4 shows the {eta}{sup 4}-2,5-Me{sub 2}T{center_dot}C{sub 5}H{sub 5} ligand to be a ring-opened 2,5-Me{sub 2}T allyl thiolate conjugated to a cyclopentadienylidene unit. The reduced products 2 and 3 react with Cp{sub 2}Co to give a ferrole-type product Cp{sup *}[IrC(Me)=CHCH=C(Me)]CoCp in which the planar iridacyclopentadiene ring is {pi}-bonded to the cobalt, as established by a structural investigation. The Cp{sup *}Co analog of 5 is prepared by the reaction of 2 or 3 with Cp{sup *}Co(CH{sub 2}=CH{sub 2}){sub 2}. These studies demonstrate that cobaltocene and Cp{sup *}Co(CH{sub 2}=CH{sub 2}){sub 2} readily desulfurize the 2,5-dimethylthiophene ligand in 2 and 3, which supports a previously proposed mechanism for the thiophene hydrodesulfurization. 37 refs., 2 figs., 5 tabs.

Chen, J.; Daniels, L.M.; Angelica, R.J. [Ames Lab., IA (United States)] [Ames Lab., IA (United States); [Iowa State Univ., Ames, IA (United States)

1996-02-20

110

reactions  

Microsoft Academic Search

Gene regulatory, signal transduction and metabolic networks are major areas of interest in the newly emerging field of systems biology. In living cells, stochastic dynamics play an important role; however, the kinetic parameters of biochemical reactions necessary for modelling these processes are often not accessible directly through experiments. The problem of estimating stochastic reaction constants from molecule count data measured,

S. Reinker; R. M. Altman; J. Timmer

111

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 Central

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, 1H-NMR, 13C-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 pKa values were determined for all cases. Thus, the effects of solvents and molecular structure upon acidity were investigated. In addition, isotropic 1H and 13C 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, ?ule; Calapo?lu, Mustafa; Elmasta?, Mahfuz; Kolomuç, Ali; Aksu, Havva

2008-01-01

112

Measurement of creatine kinase reaction rate in human brain using magnetization transfer image-selected in vivo spectroscopy (MT-ISIS) and a volume 31P/1H radiofrequency coil in a clinical 3-T MRI system  

PubMed Central

High-energy phosphate metabolism, which allows the synthesis and regeneration of adenosine triphosphate (ATP), is a vital process for neuronal survival and activity. In particular, creatine kinase (CK) serves as an energy reservoir for the rapid buffering of ATP levels. Altered CK enzyme activity, reflecting compromised high-energy phosphate metabolism or mitochondrial dysfunction in the brain, can be assessed using magnetization transfer (MT) MRS. MT 31P MRS has been used to measure the forward CK reaction rate in animal and human brain, employing a surface radiofrequency coil. However, long acquisition times and excessive radiofrequency irradiation prevent these methods from being used routinely for clinical evaluations. In this article, a new MT 31P MRS method is presented, which can be practically used to measure the CK forward reaction rate constant in a clinical MRI system employing a volume head 31P coil for spatial localization, without contamination from the scalp muscle, and an acquisition time of 30 min. Other advantages associated with the method include radiofrequency homogeneity within the regions of interest of the brain using a volume coil with image-selected in vivo spectroscopy localization, and reduction of the specific absorption rate using nonadiabatic radiofrequency pulses for MT saturation. The mean value of kf was measured as 0.320±0.075 s?1 from 10 healthy volunteers with an age range of 18–40 years. These values are consistent with those obtained using earlier methods, and the technique may be used routinely to evaluate energetic processes in the brain on a clinical MRI system. PMID:21834000

Jeong, Eun-Kee; Sung, Young-Hoon; Kim, Seong-Eun; Zuo, Chun; Shi, Xianfeng; Mellon, Eric A.; Renshaw, Perry F.

2011-01-01

113

Synthesis and Characterization of Cu(II), Ni(E), Cd(II) and Zn(II) with Salicylaldehyde1H- Benzotriazol-1-Aceylhydrazone and 2Hydroxy Naphthylaldehyde-1H- Benzotriazol-1-Aceylhydrazone  

Microsoft Academic Search

Two new ligands, salicylaldehyde— 1H-benzotriazol—1— acctylliydrazone and 2-hydroxy-naphthylaldehyde-1H-benzotriazol-1-acetyihydrazone have been synthesized and used in preparing some metal(II) complexes. Attempts have been made to ascertain their probable structures on the basis of elemental analyses, molar conductivities, IR, H NMR, TGA, UV and iluorescence spectra. It is suggested that the complexes have a four-coordinated, square-planar, dimer configuration. The IR and H NMR

Hu Youhong; Zhang Yulan; Wu Shaozu

1995-01-01

114

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.

115

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

NASA Astrophysics Data System (ADS)

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, 1H NMR, 13C-APT and LC-MS spectroscopy techniques. The FT-IR, 1H NMR and 13C-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.

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

2015-01-01

116

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

117

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

118

IRS organigram  

NASA Technical Reports Server (NTRS)

Charts and graphs relative to magnetoplasmadynamic (MPD) thruster technology are given. The research activities at the Institute of Space Transportation, University of Stuttgart, are summarized. Information is given on the Institute's Electric Propulsion and Plasma Wind Tunnel; thermal arcjet research; the nozzle-type thruster, DT-IRS; nozzle-type MPD thrusters; a hot anode thruster; the DT6 thruster; the ZT-1 thruster; the cylindrical MPD thruster; and a comparison of continuous and quasi-steady MPD.

Messerschmid, Ernst

1991-01-01

119

1H 2012Executive Summary  

E-print Network

The Global Internet Phenomena Report: 1H 2012 shines a light on fixed and mobile data networks around the world, identifying facts, fads, and the future trends that will shape the Internet’s future. Within this report, we present a mix of high-level observations, regional-focused analysis, deep-dives into specific subjects, and educational tidbits. Communications service providers (CSPs) in particular are in the position to act on this information, but we believe that the findings will be of interest to a wide range of readers. At the highest level, we observed that Real-Time Entertainment (comprised mostly of streaming video and audio) is the largest traffic category on every network we examined. Furthermore, with the sole exception of North America’s fixed access networks (where Netflix is dominant), YouTube is the largest single source of Real-Time Entertainment traffic. With appeal that crosses regions, access technologies and devices, YouTube has emerged to account for more Internet traffic than any other service. We also observed that rich communication services like WhatsApp, that replace traditional source of operator revenue, continue to enjoy widespread adoption – we counted an average of 7.6 million WhatsApp messages per day on a mobile operator with 1 million subscribers. North America’s mobile networks have the highest proportion of Real-Time Entertainment traffic – in fact, the majority of mobile data in North America is streaming audio and video. YouTube leads the way, accounting for 23.4 % of daily

unknown authors

120

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

121

Model car-exhaust catalyst studied by TPD and TP-RAIRS: Surface reactions of NO on clean and O-covered Ir{1 0 0}  

Microsoft Academic Search

The adsorption of NO on Ir{100} has been studied as a function of NO coverage and temperature using temperature programmed reflection absorption infrared spectroscopy (TP-RAIRS), low energy electron diffraction (LEED) and temperature programmed desorption (TPD). After saturating the clean (1×5)-reconstructed surface with NO at 95K, two N2 desorption peaks are observed upon heating. The first N2 peak at 346K results

Sabyasachi Khatua; Georg Held; David A. King

2005-01-01

122

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

Microsoft Academic Search

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

M. Ivanda; S Popovi?; M Goti?

1999-01-01

123

Hydroxyl radical reaction rate coefficients as a function of temperature and IR absorption cross sections for CF3CH=CH 2 (HFO-1243zf), potential replacement of CF 3CH 2F (HFC-134a).  

PubMed

CF3CH=CH2 (hydrofluoroolefin, HFO-1243zf) is a potential replacement of high global-warming potential (GWP) hydrofluorocarbon (HFC-134a, CF3CFH2). Both the atmospheric lifetime and the radiative efficiency of HFO-1243zf are parameters needed for estimating the GWP of this species. Therefore, the aim of this work is (i) to estimate the atmospheric lifetime of HFO-1243zf from the reported OH rate coefficients, k OH, determined under tropospheric conditions and (ii) to calculate its radiative efficiency from the reported IR absorption cross sections. The OH rate coefficient at 298 K also allows the estimation of the photochemical ozone creation potential (?(POCP)). The pulsed laser photolysis coupled to a laser-induced fluorescence technique was used to determine k OH for the reaction of OH radicals with HFO-1243zf as a function of pressure (50-650 Torr of He) and temperature (263-358 K). Gas-phase IR spectra of HFO-1243zf were recorded at room temperature using a Fourier transform IR spectrometer between 500 and 4,000 cm(-1). At all temperatures, k OH did not depend on bath gas concentration (i.e., on the total pressure between 50 and 650 Torr of He). A slight but noticeable T dependence of k OH was observed in the temperature range investigated. The observed behavior is well described by the following Arrhenius expression: k OH(T)?=?(7.65?±?0.26)?×?10(-13) exp [(165?±?10)?/?T]?cm(3) molecule(-1) s(-1). Negligible IR absorption of HFO-1243zf was observed at wavenumbers greater than 1,700 cm(-1). Therefore, IR absorption cross sections, [Formula: see text], were determined in the 500-1,700 cm(-1) range. Integrated [Formula: see text] were determined between 650 and 1,800 cm(-1) for comparison purposes. The main diurnal removal pathway for HFO-1243zf is the reaction with OH radicals, which accounts for 64 % of the overall loss by homogeneous reactions at 298 K. Globally, the lifetime due to OH reaction (? OH) was estimated to be 8.7 days under the assumption of a well-mixed atmosphere. Assuming other removal pathways, the atmospheric lifetime (?) was estimated to be ?6 days. Considering the estimated ? OH and the measured IR absorption cross sections of HFO-1243zf in the atmospheric window (720-1,250 cm(-1)), its lifetime corrected radiative efficiency was calculated to be 0.019 W m(-2) ppbv(-1). GWP100 years for the HFO investigated, 0.29, is negligible compared to that of HFC-134a, the HFC to be potentially replaced (GWP100 years?=?1,300, Hodnebrog et al. (Rev Geophys 51:300-378, 2013)). ? POCP for HFO-1243zf was estimated to be around 1 order of magnitude lower than that for ethylene. In conclusion, HFO-1243zf is fast degraded in the atmosphere, and it does not appreciably contribute to global warming and local/regional air pollution. Therefore, HFO-1243zf can be a suitable replacement for HFC-134a in air conditioning units. PMID:25138554

González, Sergio; Jiménez, Elena; Ballesteros, Bernabé; Martínez, Ernesto; Albaladejo, José

2015-04-01

124

Heteroleptic Ir(iii) complexes based on 2-(2,4-difluorophenyl)-pyridine and bisthienylethene: structures, luminescence and photochromic properties.  

PubMed

Two bisthienylethenes 2-(2-hydroxyphenyl)-4,5-bis[2,5-dimethyl(3-thienyl)]-1H-imidazole (L1H) and 2-(2-hydroxyphenyl)-4,5-bis(2,5-dimethyl(3-thienyl))-1-phenyl-imidazole (L2H), which have a chelating N,O-donor binding site attached to the photochromic core, have been synthesized using a one-pot condensation reaction, and used to prepare the heteroleptic complexes [Ir(dfppy)2(L1)]·2CH3OH () and [Ir(dfppy)2(L2)] () [dfppyH = 2-(2,4-difluorophenyl)-pyridine]. In the crystal structures of all four compounds, two thiophene groups of each bisthienylethene molecule adopt parallel conformation. Neighboring molecules in L1H and are linked into supramolecular chains through hydrogen bonds. Particularly, the packing structure of contains right- and left-handed 21 helical chains. In contrast, neighboring molecules in L2H and interact only through van der Waals interactions. At room temperature, L1H and L2H in CH2Cl2 show fluorescence emission at 442 nm and 469 nm, respectively. Compounds and in CH2Cl2 reveal broad emission band characteristics of the Ir(iii)/dfppy(-) chromophores at 508 nm and 494 nm, respectively, with a mixing of (3)MLCT and (3)LC characters. At room temperature, the photochromism ability of L2H in CH2Cl2 is clearly weaker than that of L1H. Moreover, no photochromism has been observed in and . It has been demonstrated that both the substituent group and {Ir(dfppy)2}(+) coordination could significantly influence the crystal structures, luminescence and photochromic properties of L1H, L2H, and . PMID:25635520

Cao, Deng-Ke; Wei, Ruo-Hong; Li, Xiao-Xiong; Chen, Jun-Feng; Ward, Michael D

2015-02-17

125

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

126

Abnormal Ligand Binding and Reversible Ring Hydrogenation in the Reaction of Imidazolium Salts with IrH5(PPh3)2  

E-print Network

Abnormal Ligand Binding and Reversible Ring Hydrogenation in the Reaction of Imidazolium SaltsVen, Connecticut 06520-8107 Received April 30, 2002 Abstract: We show that imidazolium salts do not always give complicated than previously thought. N,N-disubstituted imidazolium salts of type [(2-py)(CH2)n(C3H3N2)R]BF4

Baltisberger, Jay H.

127

Polymer hybrids of functionalized silsesquioxanes and organic polymers utilizing the sol–gel reaction of tetramethoxysilane  

Microsoft Academic Search

The ternary polymer hybrids were prepared by organic polymers such as poly(2-methyl-2-oxazoline) (POZO) or poly(N-vinylpyrrolidone) (PVP) and aminopropylsilsesquioxane (Cube-aminopropyl) utilizing the sol–gel reaction of tetramethoxysilane (TMOS). The prepared polymer hybrids were characterized by IR, thermogravimetric analysis (TGA), X-ray diffraction (XRD), 1H NMR, scanning electron microscopy (SEM), etc. In this hybrid system, hydrogen-bonding interactions played a critical role in the formation

Kyung-Min Kim; Kaoru Adachi; Yoshiki Chujo

2002-01-01

128

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

129

UV-Vis, IR spectra and thermal studies of charge transfer complexes formed in the reaction of 4-benzylpiperidine with ?- and ?-electron acceptors  

NASA Astrophysics Data System (ADS)

The reactions of the electron donor 4-benzylpiperidine (4BP) with the ?-acceptor iodine and ?-acceptors 7,7,8,8-tetracyanoquinodimethane (TCNQ), 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ), and 2,4,4,6-tetrabromo-2,5-cyclohexadienone (TBCHD) were studied spectrophotometrically in chloroform at room temperature. The electronic and infrared spectra of the formed molecular charge-transfer (CT) complexes were recorded. Based on the obtained data, the charge-transfer complexes were formulated as [I3-, [(4BP)(DDQ)2], and [(4BP)(TBCHD)] for the donor (4BP) and the acceptors I2, DDQ and TBCHD. In the 4BP-TCNQ reaction, a short-lived CT complex is formed followed by rapid N-substitution by TCNQ forming the final reaction product 7,7,8-tricyano-8-benzylpiperidinylquinodimethane [TCBPQDM]. These products were isolated as solids and have been characterized through electronic and infrared spectra as well as elemental and thermal analysis measurements. The formation constants (KCT), charge transfer energy (ECT), molar extinction coefficients (?CT), free energy change ?G? and ionization potential IP of the formed CT-complexes [I3-, [(4BP)(DDQ)2] and [(4BP)(TBCHD)] were obtained.

Mostafa, Adel; El-Ghossein, Nada; Cieslinski, G. Benjamin; Bazzi, Hassan S.

2013-12-01

130

Abnormal ligand binding and reversible ring hydrogenation in the reaction of imidazolium salts with IrH(5)(PPh(3))(2).  

PubMed

We show that imidazolium salts do not always give normal or even aromatic carbenes on metalation, and the chemistry of these ligands can be much more complicated than previously thought. N,N'-disubstituted imidazolium salts of type [(2-py)(CH(2))(n)(C(3)H(3)N(2))R]BF(4) react with IrH(5)(PPh(3))(2) to give N,C-chelated products (n = 0, 1; 2-py = 2-pyridyl; C(3)H(3)N(2) = imidazolium; R = mesityl, n-butyl, i-propyl, methyl). Depending on the circumstances, three types of kinetic products can be formed: in one, the imidazole metalation site is the normal C2 as expected; in another, the metalation occurs at the abnormal C4 site; and in the third, C4 metalation is accompanied by hydrogenation of the imidazolium ring. The bonding mode is confirmed by structural studies, and spectroscopic criteria can also distinguish the cases. Initial hydrogen transfer can take place from the metal to the carbene to give the imidazolium ring hydrogenation product, as shown by isotope labeling; this hydrogen transfer proves reversible on reflux when the abnormal aromatic carbene is obtained as final product. Care may therefore be needed in the future in verifying the structure(s) formed in cases where a catalyst is generated in situ from imidazolium salt and metal precursor. PMID:12197749

Gründemann, Stephan; Kovacevic, Anes; Albrecht, Martin; Faller, Jack W; Crabtree, Robert H

2002-09-01

131

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

PubMed

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

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

2009-02-15

132

Photochemical properties of trans-1-chloro-3,3,3-trifluoropropene (trans-CHCl?CHCF3): OH reaction rate constant, UV and IR absorption spectra, global warming potential, and ozone depletion potential.  

PubMed

Measurements of the rate constant for the gas-phase reactions of OH radicals with trans-1-chloro-3,3,3-trifluoropropene (trans-CHCl?CHCF3) were performed using a flash photolysis resonance-fluorescence technique over the temperature range 220-370 K. The reaction rate constant exhibits a noticeable curvature of the temperature dependence in the Arrhenius plot, which can be represented by the following expression: kt-CFP (220-370 K) = 1.025 × 10(-13) × (T/298)(2.29)?exp(+384/T) cm(3 )molecule(-1)?s(-1). The room-temperature rate constant was determined to be kt-CFP (298 K) = (3.29 ± 0.10) × 10(-13) cm(3)?molecule(-1)?s(-1), where the uncertainty includes both two standard errors (statistical) and the estimated systematic error. For atmospheric modeling purposes, the rate constant below room temperature can be represented by the following expression: kt-CFP (220-298 K) = (7.20 ± 0.46) × 10(-13)?exp[-(237 ± 16)/T]?cm(3)?molecule(-1)?s(-1). There was no difference observed between the rate constants determined at 4 kPa (30 Torr) and 40 kPa (300 Torr) at both 298 and 370 K. The UV and IR absorption cross sections of this compound were measured at room temperature. The atmospheric lifetime, global warming potential, and ozone depletion potential of trans-CHCl?CHCF3 were estimated. PMID:24955760

Orkin, Vladimir L; Martynova, Larissa E; Kurylo, Michael J

2014-07-17

133

Dynamic stereochemistry of erigeroside by measurement of 1H-1H and 13C-1H coupling constants.  

PubMed

Erigeroside was extracted from Satureja khuzistanica Jamzad (Marzeh Khuzistani in Persian, family of lamiaceae), and (1)H, (13)C, (13)C{(1)H}, (1)H-(1)H COSY, HMQC and J-HMBC were obtained to identify this compound and determine a complete set of J-coupling constants ((1)J(C-H), (2)J(C-H), (3)J(C-H) and (3)J(H-H)) values within the exocyclic hydroxymethyl group (CH(2)OH) and anomeric center. In parallel, density functional theory (DFT) using B3LYP functional and split-valance 6-311++G** basis set has been used to optimized the structures and conformers of erigeroside. In all calculations solvent effects were considered using a polarized continuum (overlapping spheres) model (PCM). The dependencies of (1)J, (2)J and (3)J involving (1)H and (13)C on the C(5')-C(6') (omega), C(6')-O(6') (theta) and C(1')-O(1') (phi) torsion angles in erigeroside were computed using DFT method. Complete hyper surfaces for (1)J(C1',H1'), (2)J(C5',H6'R), (2)J(C5',H6'S), (2)J(C6',H5'), (3)J(C4',H6'R), (3)J(C4',H6'S) and (2)J(H6'R-H5'S) as well as (3)J(H5',H6'R) were obtained and used to derive Karplus equations to correlate these couplings to omega, theta and phi. These calculated J-couplings are in agreement with experimental values. These results confirm the reliability of DFT calculated coupling constants in aqueous solution. PMID:18083614

Tafazzoli, Mohsen; Ghiasi, Mina; Moridi, Mahdi

2008-07-01

134

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

135

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

PubMed

Ultrafast deep-ultraviolet through near infrared (210-950 nm) transient absorption spectroscopy complemented by ab initio multiconfigurational calculations offers a global description of the photochemical reaction pathways of bromoform following 255-nm excitation in methylcyclohexane and acetonitrile solutions. Photoexcitation of CHBr3 leads to the ground-state iso-CHBr3 product in a large quantum yield (?35%), formed through two different mechanisms: concerted excited-state isomerization and cage-induced isomerization through the recombination of the nascent radical pair. These two processes take place on different time scales of tens of femtoseconds and several picoseconds, respectively. The novel ultrafast direct isomerization pathway proposed herein is consistent with the occurrence of a conical intersection between the first excited singlet state of CHBr3 and the ground electronic state of iso-CHBr3. Complete active space self-consistent field calculations characterize this singularity in the vicinity of a second order saddle point on the ground state which connects the two isomer forms. For cage-induced isomerization, both the formation of the nascent radical pair and its subsequent collapse into ground-state iso-CHBr3 are directly monitored through the deep-ultraviolet absorption signatures of the radical species. In both mechanisms, the optically active (i.e., those with largest Franck-Condon factors) C-Br-Br bending and Br-Br stretching modes of ground-state iso-CHBr3 have the largest projection on the reaction coordinate, enabling us to trace the structural changes accompanying vibrational relaxation of the non-equilibrated isomers through transient absorption dynamics. The iso-CHBr3 photoproduct is stable in methylcyclohexane, but undergoes either facile thermal isomerization to the parent CHBr3 structure through a cyclic transition state stabilized by the polar acetonitrile medium (?300-ps lifetime), and hydrolysis in the presence of water. PMID:23556730

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

2013-03-28

136

Synthesis, spectroscopic and theoretical studies of ethyl (2E)-3-amino-2-({[(4-benzoyl-1,5-diphenyl-1H-pyrazol-3-yl)carbonyl]amino}carbonothioyl)but-2-enoate butanol solvate  

NASA Astrophysics Data System (ADS)

We have synthesized ethyl (2E)-3-amino-2-({[(4-benzoyl-1,5-diphenyl-1H-pyrazol-3-yl)carbonyl]amino}carbonothioyl)but-2-enoate (2) by the reaction of 4-benzoyl-1,5-diphenyl-1H-pyrazole-3-carbonyl chloride (1), ammonium thiocyanate and ethyl 3-aminobut-2-enoate and then characterized by elemental analyses, IR, Raman, 1H NMR, 13C NMR and X-ray diffraction methods. The experimental and theoretical vibrational spectra of 2 were investigated. The experimental FT-IR (4000-400 cm-1) and Laser-Raman spectra (4000-100 cm-1) of the molecule in the solid phase were recorded. Theoretical vibrational frequencies and geometric parameters (bond lengths, bond angles) were calculated using Ab Initio Hartree Fock (HF), Density Functional Theory (B3LYP) methods with 6-311++G(d,p) basis set by Gaussian 09W program. The computed values of frequencies are scaled using a suitable scale factor to yield good coherence with the observed values. The assignments of the vibrational frequencies were performed by potential energy distribution (PED) analysis by using VEDA 4 program. The theoretical optimized geometric parameters and vibrational frequencies were compared with the corresponding experimental X-ray diffraction data, and they were seen to be in a good agreement with each other. Also, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energies were calculated.

Koca, ?rfan; Sert, Yusuf; Gümü?, Mehmet; Kani, ?brahim; Ç?rak, Ça?r?

2014-01-01

137

Rh III- and Ir III-catalyzed asymmetric transfer hydrogenation of ketones in water.  

PubMed

Asymmetric transfer hydrogenation (ATH) of ketones by formate in neat water is shown to be viable with Rh-TsDPEN and Ir-TsDPEN catalysts, derived in situ from [Cp*MCl2]2 (M=Rh, Ir) and TsDPEN. A variety of ketones were reduced, including nonfunctionalized aryl ketones, heteroaryl ketones, ketoesters, and unsaturated ketones. In comparison with Ir-TsDPEN and the related Ru II catalyst, the Rh III catalyst is most efficient in water, affording enantioselectivities of up to 99 % ee at substrate/catalyst (S/C) ratios of 100-1000 even without working under an inert atmosphere. The aqueous phase reduction is shown to be highly pH-dependent; the optimum pH windows for TOF greater than 50 mol mol(-1) h(-1) for Rh- and Ir-TsDPEN are 5.5-10.0 and 6.5-8.5, respectively. Outside the pH window, the reduction becomes slow or stagnant depending on the pH. However, the enantioselectivities erode only under acidic conditions. At a higher S/C ratio, the aqueous ATH by Rh-TsDPEN is shown to be product- as well as byproduct-inhibited; the product inhibition appears to stem at least partly from the reaction being reversible. The aqueous phase reduction is simple, efficient and environmentally benign, thus presenting a viable alternative for asymmetric reduction. PMID:18095274

Wu, Xiaofeng; Li, Xiaohong; Zanotti-Gerosa, Antonio; Pettman, Allan; Liu, Jianke; Mills, Allan James; Xiao, Jianliang

2008-01-01

138

Time-resolved FT-IR spectroscopic investigation of the pH-dependent proton transfer reactions in the E194Q mutant of bacteriorhodopsin.  

PubMed

The photoreaction of the E194Q mutant of bacteriorhodopsin has been investigated at various pH values by time-resolved step-scan Fourier-transform infrared difference spectroscopy employing the attenuated total reflection technique. The difference spectrum at pH 8.4 is comparable to the N-BR difference spectra of the wild type with the remarkable exception that D85 is deprotonated. Since the retinal configuration is not perturbed by the E194Q mutation, it is concluded that there is no interaction of D85 with retinal during the lifetime of the N state. At pH 6, a consecutive state to the O intermediate is detected in which D212 is transiently protonated. The comparison with wild-type bacteriorhodopsin reveals that protonation of D212 represents an intermediate step during proton transfer from D85 to the proton release group in the final stage of the reaction cycle. The described effects are more pronounced in the E194Q mutant than in the E204Q mutant demonstrating different roles of these two glutamates/glutamic acids at least in the final stages of the catalytic cycle of bacteriorhodopsin. PMID:11322767

Zscherp, C; Schlesinger, R; Heberle, J

2001-04-27

139

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

140

ALBERMARLE PAMLICO IR 2002  

EPA Science Inventory

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

141

Where IR you?: Using \\  

Microsoft Academic Search

Purpose – This paper aims to clarify the relationship between researcher, digital librarian, and cataloger supporting collection building in institutional repository (IR). It also aims to propose modeling the collaborative process and outline why and how cooperative partnership is important throughout the IR content building process. The study seeks to contribute to the body of knowledge of IR collection building

Plato L. Smith II

2008-01-01

142

Quantization 1. h-adic topology  

E-print Network

Quantization 1. h-adic topology 1.1 Let A be a ring. Let a be an ideal in A. We view the powers ak of the ideal a as a basis of neighborhoods in A containing 0. There is a unique topology-adic topology. If k ak = (0) then this topology is Hausdorff. 1.2 Let M be an A-module. We can transfer the a

Ram, Arun

143

1H–NMR Metabolomic Biomarkers of Poor Outcome after Hemorrhagic Shock are Absent in Hibernators  

PubMed Central

Background Hemorrhagic shock (HS) following trauma is a leading cause of death among persons under the age of 40. During HS the body undergoes systemic warm ischemia followed by reperfusion during medical intervention. Ischemia/reperfusion (I/R) results in a disruption of cellular metabolic processes that ultimately lead to tissue and organ dysfunction or failure. Resistance to I/R injury is a characteristic of hibernating mammals. The present study sought to identify circulating metabolites in the rat as biomarkers for metabolic alterations associated with poor outcome after HS. Arctic ground squirrels (AGS), a hibernating species that resists I/R injury independent of decreased body temperature (warm I/R), was used as a negative control. Methodology/principal findings Male Sprague-Dawley rats and AGS were subject to HS by withdrawing blood to a mean arterial pressure (MAP) of 35 mmHg and maintaining the low MAP for 20 min before reperfusing with Ringers. The animals’ temperature was maintained at 37±0.5°C for the duration of the experiment. Plasma samples were taken immediately before hemorrhage and three hours after reperfusion. Hydrophilic and lipid metabolites from plasma were then analyzed via 1H–NMR from unprocessed plasma and lipid extracts, respectively. Rats, susceptible to I/R injury, had a qualitative shift in their hydrophilic metabolic fingerprint including differential activation of glucose and anaerobic metabolism and had alterations in several metabolites during I/R indicative of metabolic adjustments and organ damage. In contrast, I/R injury resistant AGS, regardless of season or body temperature, maintained a stable metabolic homeostasis revealed by a qualitative 1H–NMR metabolic profile with few changes in quantified metabolites during HS-induced global I/R. Conclusions/significance An increase in circulating metabolites indicative of anaerobic metabolism and activation of glycolytic pathways is associated with poor prognosis after HS in rats. These same biomarkers are absent in AGS after HS with warm I/R. PMID:25211248

Bogren, Lori K.; Murphy, Carl J.; Johnston, Erin L.; Sinha, Neeraj; Serkova, Natalie J.; Drew, Kelly L.

2014-01-01

144

The hydrogen-bonded 2-pyridone dimer model system. 1. Combined NMR and FT-IR spectroscopy study.  

PubMed

2-Pyridone (PD), converting to 2-hydroxypyridine (HP) through a lactam-lactim isomerization mechanism, can form three different cyclic dimers by hydrogen bond formation: (PD)(2), (PD-HP), and (HP)(2). We investigate the complexation chemistry of pyridone in dichloromethane-d(2) using a combined NMR and Fourier transform infrared (FT-IR) approach. Temperature-dependent (1)H NMR spectra indicate that at low temperatures (<200 K) pyridone in solution predominantly exists as a cyclic (PD)(2) dimer, in exchange with PD monomers. At higher temperatures a proton exchange mechanism sets in, leading to a collapse of the doublet of (15)N labeled 2-pyridone. Linear FT-IR spectra indicate the existence of several pyridone species, where, however, a straightforward interpretation is hampered by extensive spectral overlap of many vibrational transitions in both the fingerprint and the NH/OH stretching regions. Two-dimensional IR correlation spectroscopy applied on concentration-dependent and temperature-dependent data sets reveals the existence of the (PD)(2) cyclic dimer, of PD-CD(2)Cl(2) solute-solvent complexes, and of PD-PD chainlike dimers. Regarding the difference in effective time scales of the NMR and FT-IR experiments, milliseconds vs (sub)picoseconds, the cyclic dimers (PD-HP) and (HP)(2), and the chainlike conformations HP-PD, may function as intermediates in reaction pathways through which the protons exchange between PD units in cyclic (PD)(2). PMID:20593823

Szyc, ?ukasz; Guo, Jing; Yang, Ming; Dreyer, Jens; Tolstoy, Peter M; Nibbering, Erik T J; Czarnik-Matusewicz, Bogus?awa; Elsaesser, Thomas; Limbach, Hans-Heinrich

2010-07-29

145

Synthesis of Hexahydro-1H-isoindole Derivatives from Arylacyl Bromides via Homoallenic Bromohydrins.  

PubMed

A procedure has been developed for the concise synthesis of hexahydro-1H-isoindole derivatives starting from phenacyl bromides. The approach employs a sequence involving an initial indium-mediated allenylation reaction of an arylacyl bromide with propargyl bromide. This process is followed by FeBr3-mediated SN2'-type substitution reaction of the formed homoallenic bromohydrin to produce a 2,5-dibromo-4-aryl-1,3-pentadiene, which then is subjected to a sequential, one-pot N-alkylation reaction with N-allyl-N-(p-tosyl)amine and a highly diastereoselective intramolecular Diels-Alder reaction of the formed ene-diene to generate the target hexahydro-1H-isoindole. PMID:25640074

Lin, Mei-Huey; Li, Yi-Syuan; Kuo, Chung-Kai; Chen, Chung-Hao; Huang, Yen-Chih; Liang, Kung-Yu; Chen, Yu-Chun; Tsai, Chang-Hsien; Chuang, Tsung-Hsun

2015-02-20

146

Infrared (IR) image synthesis method of IR real background and modeled IR target  

NASA Astrophysics Data System (ADS)

An infrared (IR) image synthesis method is proposed for the synthesis of a real IR background and modeled IR target, used as IR signatures, as well as a band-transformation between short wave IR (SWIR), middle wave IR (MWIR), and long wave IR (LWIR) in an IR imaging system simulation. IR target images are created by the RadThermIR software, an IR signature prediction software. Individual radiances for IR signatures, corresponding to the max/min temperatures of a real IR background and modeled IR target image, are calculated with Planck's law. First, an IR background of an arbitrary wavelength band is transformed to one of the other wavelength bands with the temperature-radiance characteristics. And then, after adjusting the gray levels of the arbitrary IR target signatures based on their radiances for the wavelength band of the transformed IR background, these IR target and background signatures can be synthesized as one image for a specific wavelength band. The experimental results show that the modeled IR target images, such as a modeled helicopter and F16, can be synthesized on the IR background images of three IR wavelength bands. And we confirmed that IR background images of the three IR wavelength bands can diversely be synthesized with the modeled IR targets as the setting temperature of the target and background, the target distance, and the field of view (FOV) arbitrarily.

Kim, Young-Choon; Bae, Tae-Wuk; Kwon, Hyuk-Ju; Kim, Byoung-Ik; Ahn, Sang-Ho

2014-03-01

147

Hydrophobization of epoxy nanocomposite surface with 1H,1H,2H,2H-perfluorooctyltrichlorosilane for superhydrophobic properties  

NASA Astrophysics Data System (ADS)

Nature inspires the design of synthetic materials with superhydrophobic properties, which can be used for applications ranging from self-cleaning surfaces to microfluidic devices. Their water repellent properties are due to hierarchical (micrometer- and nanometre-scale) surface morphological structures, either made of hydrophobic substances or hydrophobized by appropriate surface treatment. In this work, the efficiency of two surface treatment procedures, with a hydrophobic fluoropolymer, synthesized and deposited from 1H,1H,2H,2H-perfluorooctyltrichlorosilane (PFOTS) is investigated. The procedures involved reactions from the gas and liquid phases of the PFOTS/hexane solutions. The hierarchical structure is created in an epoxy nanocomposite surface, by filling the resin with alumina nanoparticles and micron-sized glass beads and subsequent sandblasting with corundum microparticles. The chemical structure of the deposited fluoropolymer was examined using XPS spectroscopy. The topography of the modified surfaces was characterized using scanning electron microscopy (SEM), and atomic force microscopy (AFM). The hydrophobic properties of the modified surfaces were investigated by water contact and sliding angles measurements. The surfaces exhibited water contact angles of above 150° for both modification procedures, however only the gas phase modification provided the non-sticking behaviour of water droplets (sliding angle of 3°). The discrepancy is attributed to extra surface roughness provided by the latter procedure.

Psarski, Maciej; Marczak, Jacek; Celichowski, Grzegorz; Sobieraj, Grzegorz; Gumowski, Konrad; Zhou, Feng; Liu, Weimin

2012-10-01

148

Observation of (1)H-(13)C and (1)H-(1)H proximities in a paramagnetic solid by NMR at high magnetic field under ultra-fast MAS.  

PubMed

The assignment of NMR signals in paramagnetic solids is often challenging since: (i) the large paramagnetic shifts often mask the diamagnetic shifts specific to the local chemical environment, and (ii) the hyperfine interactions with unpaired electrons broaden the NMR spectra and decrease the coherence lifetime, thus reducing the efficiency of usual homo- and hetero-nuclear NMR correlation experiments. Here we show that the assignment of (1)H and (13)C signals in isotopically unmodified paramagnetic compounds with moderate hyperfine interactions can be facilitated by the use of two two-dimensional (2D) experiments: (i) (1)H-(13)C correlations with (1)H detection and (ii) (1)H-(1)H double-quantum?single-quantum correlations. These methods are experimentally demonstrated on isotopically unmodified copper (II) complex of l-alanine at high magnetic field (18.8T) and ultra-fast Magic Angle Spinning (MAS) frequency of 62.5kHz. Compared to (13)C detection, we show that (1)H detection leads to a 3-fold enhancement in sensitivity for (1)H-(13)C 2D correlation experiments. By combining (1)H-(13)C and (1)H-(1)H 2D correlation experiments with the analysis of (13)C longitudinal relaxation times, we have been able to assign the (1)H and (13)C signals of each l-alanine ligand. PMID:25557861

Li, Shenhui; Trébosc, Julien; Lafon, Olivier; Zhou, Lei; Shen, Ming; Pourpoint, Frédérique; Amoureux, Jean-Paul; Deng, Feng

2015-02-01

149

WebSpectra: Problems in NMR and IR Spectroscopy  

NSDL National Science Digital Library

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

150

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.

151

Web Spectra: Problems in NMR and IR spectroscopy  

NSDL National Science Digital Library

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

Merlic, Craig A.

152

Isolation and structural characterization of anionic and neutral compounds resulting from the oxidative addition of HI or CH3I to [IrI2(CO)2](-).  

PubMed

The active iridium species in the methanol carbonylation reaction has been crystallized as the [PPN][IrI(2)(CO)(2)] complex and the X-ray structure solved, showing a cis-geometry and a square planar environment. Hydriodic acid reacts very quickly with this compound to provide [PPN][IrHI(3)(CO)(2)], the X-ray crystal structure of which has been determined. The two CO ligands remain in mutual cis-position in a pseudooctahedral environment. The same cis-arrangement has been observed from the X-ray structure for [PPN][IrI(3)(CH(3))(CO)(2)] resulting from the slower oxidative addition of CH(3)I to [PPN][IrI(2)(CO)(2)]. By iodide abstraction with InI(3), the anionic methyl complex gave rise to the dimeric neutral complex [Ir(2)(mu-I)(2)I(2)(CH(3))(2)(CO)(4)]. An X-ray structure showed that the methyl ligands are in the equatorial positions of the two octahedrons sharing an edge, formed by the two bridging iodide ligands. All these four complexes have been fully characterized by mass spectrometry, (1)H and (13)C NMR, and infrared both in solution and in the solid state. When necessary, the (13)CO- or (13)CH(3)-enriched complexes have been prepared and analyzed. PMID:12950199

Gautron, Samuel; Giordano, Roberto; Le Berre, Carole; Jaud, Joël; Daran, Jean-Claude; Serp, Philippe; Kalck, Philippe

2003-09-01

153

IR Hot Wave  

SciTech Connect

The IR Hot Wave{trademark} furnace is a breakthrough heat treatment system for manufacturing metal components. Near-infrared (IR) radiant energy combines with IR convective heating for heat treating. Heat treatment is an essential process in the manufacture of most components. The controlled heating and cooling of a metal or metal alloy alters its physical, mechanical, and sometimes chemical properties without changing the object's shape. The IR Hot Wave{trademark} furnace offers the simplest, quickest, most efficient, and cost-effective heat treatment option for metals and metal alloys. Compared with other heat treatment alternatives, the IR Hot Wave{trademark} system: (1) is 3 to 15 times faster; (2) is 2 to 3 times more energy efficient; (3) is 20% to 50% more cost-effective; (4) has a {+-}1 C thermal profile compared to a {+-}10 C thermal profile for conventional gas furnaces; and (5) has a 25% to 50% smaller footprint.

Graham, T. B.

2010-04-01

154

Simulations 'picture' IR scenes  

NASA Astrophysics Data System (ADS)

A computer simulation code, designated Spectral IR Imaging of Targets and Scenes (SPIRITS), has been integrated with the CLOUD IR Cloud-Irradiance Model to create the IR Scene Generator 1.0; the additional code AERIE, for terrain-background modeling, will in due course be incorporated as well. SPIRITS calculates and displays contrast-IR target image radiance and spectral radial intensity plots for targets of simulated air-to-air engagements in the 1-20 micron IR region. Scenarios can be planned through a motion interface which allows the user to move the target within a scene and produce a sequence of images: this makes possible the evaluation of algorithms for detection and tracking of targets in cluttered backgrounds.

Scott, Herman

1990-01-01

155

Sulfur-containing hyperbranched polymeric photoinitiator end-capped with benzophenone and tertiary amine moieties prepared via simultaneous double thiol-ene click reactions used for UV curing coatings  

Microsoft Academic Search

A series of sulfur-containing hyperbranched polymeric photoinitiators end-capped with benzophenone (BP) and tertiary amine moieties (B\\/A-HPIs) were synthesized via the simultaneous double thiol-ene click reactions of thiolated hyperbranched polymer with both dimethylaminoethyl acrylate and 3-(4-benzoylphenoxy)propyl acrylate. The molecular structures were characterized by 1H NMR and FT-IR spectroscopy. From the UV–vis spectra, B\\/A-HPIs showed the stronger n-?* absorption at ?340nm with

Han Xie; Lihua Hu; Yong Zhang; Wenfang Shi

2011-01-01

156

Genetic Variation in Myosin 1H Contributes to Mandibular Prognathism  

PubMed Central

Introduction Several candidate loci have been suggested as influencing mandibular prognathism (1p22.1, 1p22.2, 1p36, 3q26.2, 5p13-p12, 6q25, 11q22.2-q22.3, 12q23, 12q13.13, and 19p13.2). The goal of this study was to replicate these results in a well-characterized homogeneous sample set. Methods Thirty-three single nucleotide polymorphisms spanning all candidate regions were studied in 44 prognathic and 35 Class I subjects from the University of Pittsburgh School of Dental Medicine Dental Registry and DNA Repository. The 44 mandibular prognathism subjects had an average age of 18.4 years, 31 were females and 13 males, and 24 were White, 15 African American, two Hispanic, and three Asian. The 35 Class I subjects had an average age of 17.6 years, 27 were females and 9 males, and 27 were White, six African Americans, one Hispanic, and two Asian. Skeletal mandibular prognathism diagnosis included cephalometric values indicative of Class III such as ANB smaller than two degrees, negative Witts appraisal, and positive A–B plane. Additional mandibular prognathism criteria included negative OJ and visually prognathic (concave) profile as determined by the subject's clinical evaluation. Orthognathic subjects without jaw deformations were used as a comparison group. Mandibular prognathism and orthognathic subjects were matched based on race, sex and age. Genetic markers were tested by polymerase chain reaction using TaqMan chemistry. Chi-square and Fisher exact tests were used to determine overrepresentation of marker allele with alpha of 0.05. Results An association was unveiled between a marker in MYO1H (rs10850110) and the mandibular prognathism phenotype (p=0.03). MYO1H is a Class-I myosin that is in a different protein group than the myosin isoforms of muscle sarcomeres, which are the basis of skeletal muscle fiber typing. Class I myosins are necessary for cell motility, phagocytosis and vesicle transport. Conclusions More strict clinical definitions may increase homogeneity and aid the studies of genetic susceptibility to malocclusions. We provide evidence that MYO1H may contribute to mandibular prognathism. PMID:22196185

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

2013-01-01

157

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...

158

IR in Norway  

NASA Astrophysics Data System (ADS)

Infrared technology in Norway started at the Norwegian Defense Research Establishment (FFI) in the 1960s, and has since then spread to universities, other research institutes and industry. FFI has a large, integrated IR activity that includes research and development in IR detectors, optics design, optical coatings, advanced dewar design, modelling/simulation of IR scenes, and image analysis. Part of the integrated activity is a laboratory for more basic research in materials science and semiconductor physics, in which thin films of CdHgTe are grown by molecular beam epitaxy and processed into IR detectors by various techniques. FFI also has a lot of experience in research and development of tunable infrared lasers for various applications. Norwegian industrial activities include production of infrared homing anti-ship missiles, laser rangefinders, various infrared gas sensors, hyperspectral cameras, and fiberoptic sensor systems for structural health monitoring and offshore oil well diagnostics.

Haakenaasen, Randi; Lovold, Stian

2003-01-01

159

Synthetic IR scene generation  

NASA Astrophysics Data System (ADS)

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

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

1988-01-01

160

Te-Te and Te-C bond cleavage reactions using a monovalent gallanediyl.  

PubMed

LGa (L = [(2,6-i-Pr2-C6H3)NC(Me)]2CH) reacts with elemental tellurium with formation of the Te-bridged compound [LGa-?-Te]2, whereas the reactions with Ph2Te2 and i-Pr2Te occurred with cleavage of the Te-Te and Te-C bond, respectively, and subsequent formation of LGa(TePh)2 and LGa(i-Pr)Tei-Pr . were characterized by heteronuclear NMR ((1)H, (13)C, (125)Te) and IR spectroscopy and their solid state structures were determined by single crystal X-ray analyses. PMID:25680084

Ganesamoorthy, Chelladurai; Bendt, Georg; Bläser, Dieter; Wölper, Christoph; Schulz, Stephan

2015-03-01

161

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

162

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.  

PubMed

The title molecular salt (2), 2,2'-(pyridine-2,6-diyl)bis(1H-benzo[d]imidazol-3-ium) 2,4,6-trimethylbenzenesulfonate chloride (C19H15N5(2+)·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. PMID:24825668

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

2014-10-15

163

Analysis of pharmaceutical heparins and potential contaminants using (1)H-NMR and PAGE.  

PubMed

In 2008, heparin (active pharmaceutical ingredient, API) lots were associated with anaphylactoid-type reactions. Oversulfated chondroitin sulfate (OSCS), a semi-synthetic glycosaminoglycan (GAG), was identified as a contaminant and dermatan sulfate (DS) as an impurity. While DS has no known toxicity, OSCS was toxic leading to patient deaths. Heparins, prepared before these adverse reactions, needed to be screened for impurities and contaminants. Heparins were analyzed using high-field (1)H-NMR spectroscopy. Heparinoids were mixed with a pure heparin and analyzed by (1)H-NMR to assess the utility of (1)H-NMR for screening heparin adulterants. Sensitivity of heparinoids to deaminative cleavage, a method widely used to depolymerize heparin, was evaluated with polyacrylamide gel electrophoresis to detect impurities and contaminants, giving limits of detection (LOD) ranging from 0.1% to 5%. Most pharmaceutical heparins prepared between 1941 and 2008 showed no impurities or contaminants. Some contained DS, CS, and sodium acetate impurities. Heparin prepared in 2008 contained OSCS contaminant. Heparin adulterated with heparinoids showed additional peaks in their high-field (1)H-NMR spectra, clearly supporting NMR for monitoring of heparin API with an LOD of 0.5-10%. Most of these heparinoids were stable to nitrous acid treatment suggesting its utility for evaluating impurities and contaminants in heparin API. PMID:19642166

Zhang, Zhenqing; Li, Boyangzi; Suwan, Jiraporn; Zhang, Fuming; Wang, Zhenyu; Liu, Haiying; Mulloy, Barbara; Linhardt, Robert J

2009-11-01

164

Synthesis, characterization, antimicrobial, DNA-cleavage and antioxidant activities of 3-((5-chloro-2-phenyl-1H-indol-3-ylimino)methyl)quinoline-2(1H)-thione and its metal complexes  

NASA Astrophysics Data System (ADS)

Schiff base 3-((5-chloro-2-phenyl-1H-indol-3-ylimino)methyl)quinoline-2(1H)-thione and its Cu(II), Co(II), Ni(II), Zn(II) and Fe(III), complexes have been synthesized and characterized by elemental analysis, UV-Visible, IR, 1H NMR, 13C NMR and mass spectra, molar conductance, magnetic susceptibility, ESR and TGA data. The ligand and its metal complexes have been screened for their antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa, antifungal activity against Aspergillus niger and Aspergillus flavus in minimum inhibition concentration (MIC) by cup plate method respectively, antioxidant activity using 1,1-diphenyl-2-picryl hydrazyl (DPPH), which was compared with that of standard drugs vitamin-C and vitamin-E and DNA cleavage activity using calf-thymus DNA.

Vivekanand, B.; Mahendra Raj, K.; Mruthyunjayaswamy, B. H. M.

2015-01-01

165

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

166

Synthesis and Characterization of 5-(4-(3-Trimethoxysilyl)Propoxy)Phenyl)-1H-Tetrazole  

Microsoft Academic Search

N-heterocyclic molecules, bearing nitrogen atoms and conjugate ring and having protogenic proton conductivity, can be used as proton conducting functional group for proton exchange membrane (PEM). In this paper, 5-(4-hydroxyphenyl)-1H- tetrazole (b) was synthesized using 4-cyanophenol (a) and sodium azide as main materials and water as solvent by click chemistry. The optimum reaction conditions were obtained by orthogonal test design

Dongjie Wang; Chunpeng Niu; Jiang Long; Huiping Li; MinKyu Song; Meilin Liu

2012-01-01

167

Selective syntheses of leuconolam, leuconoxine, and mersicarpine alkaloids from a common intermediate through regiocontrolled cyclizations by Staudinger reactions† †Electronic supplementary information (ESI) available: Experimental details and procedures, compound characterization data, copies of 1H and 13C NMR spectra for new compounds. See DOI: 10.1039/c4qo00312h Click here for additional data file.  

PubMed Central

Selective syntheses of leuconolam, leuconoxine, and mersicarpine alkaloids bearing distinctive core structures were achieved through Staudinger reactions using a common intermediate. In the key cyclization step, water functioned like a switch to control which core structure to produce. The chemistry allowed for selective syntheses of the group of alkaloids from a simple intermediate through straightforward chemical operations. PMID:25717379

Li, Zining; Geng, Qian; Lv, Zhe; Pritchett, Beau P.; Baba, Katsuaki; Numajiri, Yoshitaka

2015-01-01

168

Luminescent cyanometallates based on phenylpyridine-Ir(III) units: solvatochromism, metallochromism, and energy-transfer in Ir/Ln and Ir/Re complexes.  

PubMed

[Ir(ppy)(2)(CN)(2)](-) (ppy = anion of 2-phenylpyridine) and some substituted derivatives have been investigated for their ability to interact with additional metal cations, both in solution and the solid state, via the externally-directed cyanide lone pairs, and to act as energy-donors in the resulting assemblies. [Ir(ppy)(2)(CN)(2)](-) is slightly solvatochromic, showing a blue-shift of the lowest energy absorption manifold in water compared to organic solvents, and the solubilised (t)Bu-substituted analogue [Ir((t)Buppy)(2)(CN)(2)](-) [(t)Buppy = anion of 2-(4-(t)Bu-phenyl)pyridine] is also metallochromic with coordination of the cyanide lone pairs to two M(II) cations in MeCN (M = Ba, Zn) resulting in blue-shifts of the lowest-energy absorption and emission maxima. These effects are however modest because of (i) the presence of only two cyanide groups, and (ii) the fact that the lowest-energy excited state has a substantial (3)LC component and is therefore not purely charge-transfer in nature. Crystallisation of [Ir(ppy)(2)(CN)(2)](-) as its (PPN)(+) salt in the presence of excess of lanthanide(III) salts leads to formation of assemblies based on Ir-CN-Ln bonds, which generate in the solid state either Ir(2)Ln(2)(?-CN)(4) square assemblies or linear trinuclear species with Ir-CN-Ln-NC-Ir cores. In the Ir(2)Eu(2)(?-CN)(4) and Ir(2)Nd(2)(?-CN)(4) complexes the Ir-based emission is substantially quenched due to energy-transfer to lower-lying f-f states of these lanthanide ions. In addition reaction of [Ir(F(2)ppy)(2)(CN)(2)](-) [F(2)ppy = cyclometallating anion of 2-(2,4-difluorophenyl)pyridine] with [Re(phen)(CO)(3)(MeCN)][PF(6)] in solution affords dinuclear IrRe and trinuclear IrRe(2) species in which {Re(phen)(CO)(3)} units are attached to the N-donor termini of one or both of the cyanide groups; these complexes have been structurally characterised and display quantitative Ir?Re energy-transfer, showing luminescence only from the Re(I) terminus on excitation of the Ir(III) unit. PMID:22216419

Ali, Noorshida Mohd; MacLeod, Voirrey L; Jennison, Petter; Sazanovich, Igor V; Hunter, Christopher A; Weinstein, Julia A; Ward, Michael D

2012-02-28

169

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

PubMed Central

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., Synthesis 2006, 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 of tert-butyl propiolate rather than methyl propiolate gave tert-butyl (E)-3-(1-methyl-1H-imidazol-2-ylthio)acrylate as the predominant isomer. Acid hydrolysis of the intermediate ester afforded the target compound. 3-(1-Methyl-1H-imidazol-2-ylthio)propanoic acid was synthesized from 3-bromopropanoic acid and methimazole under conditions that gave preferential substitution on sulfur and minimized substitution on nitrogen. PMID:24882887

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

2014-01-01

170

Synthesis of 3-(1-Methyl-1H-imidazol-2-ylthio)propanoic Acid and (E)-3-(1-Methyl-1H-imidazol-2-ylthio)acrylic Acid.  

PubMed

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., Synthesis 2006, 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 of tert-butyl propiolate rather than methyl propiolate gave tert-butyl (E)-3-(1-methyl-1H-imidazol-2-ylthio)acrylate as the predominant isomer. Acid hydrolysis of the intermediate ester afforded the target compound. 3-(1-Methyl-1H-imidazol-2-ylthio)propanoic acid was synthesized from 3-bromopropanoic acid and methimazole under conditions that gave preferential substitution on sulfur and minimized substitution on nitrogen. PMID:24882887

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

2013-01-01

171

BUZZARDS BAY IR, 2002  

EPA Science Inventory

The 2002 Buzzards Bay Implementation Review (IR) summarizes the progress and challenges ahead for the Buzzards Bay Project. Major new completed actions during the past two years include: designation of Buzzards Bay as a no discharge area in August 2000; full support by the Massac...

172

Ultimate IR horizon sensor  

Microsoft Academic Search

The accuracy of presently available IR horizon sensors is not sufficient to meet the stringent attitude sensing and control requirements for future remote sensing and meteorological satellites. The different sources of error in a horizon sensor are analyzed. The accuracy of the sensor is presently limited by the detector noise. Use of HgCdTe in place of an immersed bolometer detector,

Y. K. Jain; T. K. Alex; B. Kalakrishnan

1980-01-01

173

LARP Joint IR studies  

E-print Network

LARP initiated Joint IR Studies (JIRS) in October 2007 (FY2008) to coordinate efforts related to the LHC Phase I and II upgrades previously situated either in Accelerator Systems or in Magnet Systems. This note outlines JIRS goals, main directions and milestones.

Zlobin, A V

2008-01-01

174

In vivo activity of a phospholipase C inhibitor, 1-(6-((17beta-3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione (U73122), in acute and chronic inflammatory reactions.  

PubMed

To investigate the role of phospholipase C (PLC) in inflammatory processes, we tested 1-(6-((17beta-3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione (U73122), a widely used PLC inhibitor, in several in vitro and in vivo assays. We first examined the effects of U73122 on human phospholipase C-beta (PLC-beta) isozymes and found that U73122 significantly inhibited recombinant human PLC-beta2, with an IC(50) of approximately 6 microM. U73122 had little effect on PLC-beta1, PLC-beta3, or PLC-beta4. Consistent with its ability to inhibit PLC-beta2 enzymatic activity, U73122 reduced interleukin-8 and leukotriene B(4)-induced Ca(2+) flux and chemotaxis in human neutrophils in a concentration-dependent manner. In vivo, U73122 blocked carrageenan-induced hind paw edema in rats, carrageenan-induced macrophage and lymphocyte accumulation into subcutaneous chambers in dogs, lipopolysaccharide-induced macrophage, lymphocyte infiltration and prostaglandin E(2) production in a mouse peritonitis model, and 12-O-tetradecanoylphorbol-13-acetate-induced ear edema in mice. These results implicate PLC-dependent signaling pathways in the development of acute and chronic inflammatory responses in vivo. PMID:14730005

Hou, Cuifen; Kirchner, Thomas; Singer, Monica; Matheis, Michele; Argentieri, Dennis; Cavender, Druie

2004-05-01

175

Copper-Catalyzed Arylation of 1H-Perfluoroalkanes  

PubMed Central

A general method has been developed for arylation of readily available 1H-perfluoroalkanes. The method employs aryl iodide and 1H-perfluoroalkane reagents, DMPU solvent, TMP2Zn base, and a copper chloride/phenanthroline catalyst. Preliminary mechanistic studies are reported. PMID:21627068

Popov, Ilya; Lindeman, Sergey; Daugulis, Olafs

2011-01-01

176

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

177

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

178

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

PubMed

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 cyclo-octa-1,5-diene). The asymmetric unit consists of one Ir(III) 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 Ir(III) atoms is disordered across an inversion center with each O atom having a 50% site occupancy. Each Ir(III) 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 mol-ecules hydrogen bond to two BF4 (-) anions in the unit cell. PMID:24826089

Merola, Joseph; Husebo, Trang Le

2014-04-01

179

?-Oxido-bis­[hydridotris(tri­methyl­phosphane-?P)iridium(III)](Ir—Ir) bis­(tetra­fluorido­borate) 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

180

Observation of signature inversion in odd-odd 178Ir  

NASA Astrophysics Data System (ADS)

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

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

2000-07-01

181

Pulsed IR inductive lasers  

NASA Astrophysics Data System (ADS)

Pulsed inductive discharge is a new alternative method of pumping active gas laser media. The work presents results of experimental investigations of near, mid, and far IR inductive gas lasers (H2, HF, and CO2) operating at different transitions of atoms and molecules with different mechanisms of formation of inversion population. The excitation systems of a pulsed inductive cylindrical discharge (pulsed inductively coupled plasma) and pulsed RF inductive discharge in the gases are developed. Various gas mixtures including H2, N2, He, Ne, F2, NF3, and SF6 are used. Characteristics of near IR H2 laser radiation are investigated. Maximal pulse peak power of 7?kW is achieved. The possibility of using a pulsed inductive discharge as a new method of pumping HF laser active medium is demonstrated. The pulsed RF inductive CO2 laser is created and a total efficiency of 17% is achieved.

Razhev, A. M.; Churkin, D. S.; Kargapol’tsev, E. S.

2014-07-01

182

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

183

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

184

Nighttime IR Ejecta  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

Today's crater is slightly older than one shown yesterday. The ballistically emplaced ejecta is now a uniform gray tone in this nighttime IR image. With time dust will cover young surfaces and control the IR image tone. This crater is located east of Huygens Crater.

Image information: IR instrument. Latitude -10.6, Longitude 64.3 East (295.7 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

185

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

186

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

187

Synthesis, crystal structure, insecticidal activity and DFT study on the geometry and vibration of O-( E)-1-{1-[(6-chloropyridin-3-yl)methyl]-5-methyl-1 H-1,2,3-triazol-4-yl}ethyleneamino- O-ethyl- O-phenylphosphorothioate  

NASA Astrophysics Data System (ADS)

The title compound, O-( E)-1-{1-[(6-chloropyridin-3-yl)methyl]-5-methyl-1 H-1,2,3-triazol-4-yl}ethyleneamino- O-ethyl- O-phenylphosphorothioate, has been synthesized via the condensation reaction of 1-{1-[(6-chloropyridin-3-yl)methyl]-5-methyl-1 H-1,2,3-triazol-4-yl}ethanone oxime and O-ethyl- O-phenylphosphorochloridothioate in the presence of NaOH powder in refluxing EtOH. Its structure was characterized by 1H NMR, FTIR, Raman, elemental analysis and X-ray single crystal diffraction. The results of preliminary bioassays indicated that the title compound displays good insecticidal activity. Density functional (DFT) calculations have been carried out for the title compound by using the Becke-Lee-Yang-Parr's three-parameter hybrid functional (B3LYP) method at 6-31G** and 6-31G* basis sets. The calculated results show that the predicted geometry can well reproduce the structural parameters. The vibrational wave numbers of the title compound were calculated at same level. Predicted vibrational frequencies have been assigned and compared with experimental IR and Raman spectra and they are supported each other.

Shi, De-Qing; Zhu, Xiao-Fei; Song, Yuan-Zhi

2008-12-01

188

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.

189

Tyrrhena Patera Nighttime IR  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

Like yesterday's image, the small unnamed channel in this nighttime IR image is located near Tyrrhena Patera. This channel is located to the northwest of the volcanic complex and likely formed by fluvial action.

NOTE: in nighttime images North is to the bottom of the image.

Image information: IR instrument. Latitude -24.6, Longitude 349.7 East (10.3 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

190

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

191

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

192

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

PubMed Central

A one-pot synthesis of osmium(IV) complexes with two different tautomers of indazole, 1H-indazole and 2H-indazole, namely (H2ind)[OsIVCl5(2H-ind)] (1) and (H2ind)[OsIVCl5(1H-ind)] (2) is reported. Both compounds have been comprehensively characterized by NMR spectroscopy, ESI (electrospray ionization) mass spectrometry, electronic absorption spectroscopy, IR spectroscopy, cyclic voltammetry and tested for antiproliferative activity in vitro in three human cancer cell lines, CH1 (ovarian carcinoma), A549 (non-small cell lung cancer) and SW480 (colon carcinoma), as well as in vivo in a Hep3B SCID mouse xeno-transplantation model. 2H-Indazole tautomer stabilization in 1 has been confirmed by X-ray diffraction. PMID:22687494

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

2012-01-01

193

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

194

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

195

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

2014-11-14

196

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

Microsoft Academic Search

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

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

2007-01-01

197

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

198

Integrated IR sensors  

NASA Astrophysics Data System (ADS)

Integrated infrared (IR) sensors which exploit modular avionics concepts can provide features such as operational flexibility, enhanced stealthiness, and ease of maintenance to meet the demands of tactical, airborne sensor systems. On-board, tactical airborne sensor systems perform target acquisition, tracking, identification, threat warning, missile launch detection, and ground mapping in support of situation awareness, self-defense, navigation, target attack, weapon support, and reconnaissance activities. The use of sensor suites for future tactical aircraft such as US Air Force's multirole fighter require a blend of sensor inputs and outputs that may vary over time. It is expected that special-role units of these tactical aircraft will be formed to conduct tasks and missions such as anti-shipping, reconnaissance, or suppression of enemy air defenses.

Tom, Michael; Trujillo, Edward

1994-06-01

199

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

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

200

New insights into the solvent-assisted excited-state double proton transfer of 2-(1H-pyrazol-5-yl)pyridine with alcoholic partners: A TDDFT investigation.  

PubMed

Excited-state double proton transfer (ESDPT) in the hydrogen-bonded 2-(1H-pyrazol-5-yl)pyridine with propyl alcoholic partner (PPP) was theoretically investigated by time-dependent density functional theory (TDDFT) method. Great changes have taken place for the calculated geometric structures, the electron density features and vibrational spectrum of PPP system in S0 and S1 state. Our results have demonstrated that ESDPT reaction happens within the system upon photoexcitation. We also found that the ESDPT process is facilitated by the electronically excited state intermolecular hydrogen bond strengthening. Particularly, after the photoexcitation from HOMO(?) to the LUMO(?(?)), the rearrangement of electronic density distribution of frontier molecular orbitals (MOs) on pyridine and the pyrazol moieties exhibits a very important positive factor for the ESDPT. Furthermore, by the investigation of the stretching vibrations of NH and OH groups, the infrared (IR) spectroscopic results provide us not only a theoretical evidence of ESDPT, but also a considerable clue to characterize the nature of intermolecular reaction. In addition, efforts have also been devoted towards calculating the absorption peak, which shows good consistency with the experimental result of the studied system. PMID:25679182

Li, Hui; Shi, Ying; Yin, Hang; Wang, Ye; Cong, Lin; Jin, Mingxing; Ding, Dajun

2015-04-15

201

IR thermocycler for centrifugal microfluidic platform with direct on-disk wireless temperature measurement system  

Microsoft Academic Search

The direct on-disk wireless temperature measurement system [1,2] presented at muTAS 2010 was further improved in its robustness. We apply it to an IR thermocycler as part of a centrifugal microfluidic analyzer for polymerase chain reactions (PCR). This IR thermocycler allows the very efficient direct heating of aqueous liquids in microfluidic cavities by an IR radiation source. The efficiency factor

J. Burger; A. Gross; D. Mark; G. Roth; F. von Stetten; R. Zengerle

2011-01-01

202

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

203

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

204

Graphite catalyzed solvent free synthesis of dihydropyrimidin-2(1H)-ones/thiones and their antidiabetic activity.  

PubMed

A solvent free three component condensation reaction between an aldehyde, ethyl acetoacetate and urea catalyzed by graphite, a green catalyst is described for the synthesis of dihydropyrimidin-2(1H)-ones. This protocol is scalable and the catalyst is reusable. This method is also applied for the synthesis of dihydropyrimidin-2(1H)-thiones. ?-Amylase, a key enzyme in carbohydrate metabolism is generally targeted for management of type 2 diabetes. The therapeutic potential of the dihydropyrimidinones and dihydropyrimidinthiones to inhibit ?-amylase activity was evaluated by in vitro assay. Of the synthesized compounds 3,4-dihydropyrimidin-2(1H)-thione (1k) demonstrated highest inhibition of ?-amylase activity. PMID:24835627

Dhumaskar, Kashinath L; Meena, Surya Nandan; Ghadi, Sanjeev C; Tilve, Santosh G

2014-07-01

205

Shared epitope for monoclonal IR162 between Anisakis simplex larvae and Clonorchis sinensis and cross-reactivity between antigens.  

PubMed

IR162 is a rat monoclonal IgE antibody (mAb). In the investigation of rat IgE production, the antigens recognized by IR162 (IR-Ags) were found to be expressed by a variety of helminthic parasites. By western blot analysis, IR162 detected bands in crude extracts of Anisakis simplex larvae, Clonorchis sinensis, Paragonimus westermani, plerocercoids of Spirometra mansoni, and Toxocara canis. Excretory-secretory material from A. simplex larvae also contained a protein recognized by IR162. IR162 mAb obtained from both Serotec and Zymed recognized identical bands of A. simplex larvae. Sandwich enzyme-linked immunosorbent assay analysis indicated that both IR-Ags of A. simplex larvae (IR-As) and C. sinensis (IR-Cs) were important antigens with respect to induction of specific IgG in human infections with these 2 organisms. Even though minimal cross-reaction between IR-As and IR-Cs was observed using sera from infected individuals, these results indicate that IR-Ags are found in the parasites examined, that IR-As and IR-Cs are the antigens that induce specific antibody in natural infection, and that the epitope that binds IR162 is shared by A. simplex larvae and C. sinensis. PMID:11128497

Cho, J K; Cho, S W

2000-10-01

206

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

207

Applications of 1H-NMR to Biodiesel Research  

Technology Transfer Automated Retrieval System (TEKTRAN)

Biodiesel is an alternative diesel fuel derived from vegetable oils, animal fats, or used cooking oils. It is produced by reacting these materials with an alcohol in the presence of a catalyst to give the corresponding mono-alkyl esters. 1H-NMR is a routine analytical method that has been used for...

208

Appendix 1-H College of William and Mary  

E-print Network

Appendix 1-H College of William and Mary Department of Intercollegiate Athletics Policy for Adding standards as set by the College of William and Mary and the National Collegiate Athletic Association (NCAA, by its nature, must be a competitive athletic activity, requiring a high level of physical conditioning

Swaddle, John

209

Complete 1H and 13C spectral assignment of floridoside.  

PubMed

Floridoside (2-O-alpha-D-galactopyranosylglycerol) was extracted from the red marine alga Rhodymenia palmata, and purified by ion-exchange chromatography: 1D and 2D NMR spectroscopy experiments were used to unambiguously assign the complete 1H and 13C spectra. PMID:11844498

Simon-Colin, Christelle; Kervarec, Nelly; Pichon, Roger; Deslandes, Eric

2002-02-11

210

The influence of a 1 h nap on performance overnight  

Microsoft Academic Search

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

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

1989-01-01

211

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.

212

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

213

Triplet Organometallic Reactivity under Ambient Conditions: An Ultrafast UV Pump/IR Probe Study  

E-print Network

Triplet Organometallic Reactivity under Ambient Conditions: An Ultrafast UV Pump/IR Probe Study-temperature solution using femtosecond UV pump IR probe spectroscopy. Specifically, the Si-H bond-activation reaction, 841. (7) Burdett, J. K. J. Chem. Soc., Faraday Trans. 2. 1974, 70, 1599. (8) Daniel, C.; Benard, M

Harris, Charles B.

214

Higher energy electronic transitions of HC2n+1H+ ,,n=27... and HC2n+1H  

E-print Network

of Sciences, Al. Lotników 32-46, Pl-02668 Warsaw, Poland Received 3 April 2010; accepted 25 May 2010 to other carbon chains. The B~ 3 u - X~ 3 g - transition in the UV of neutral HC2n+1H n=4­7 has also been were detected in carbon- rich protoplanetary nebulae.14 Particularly interesting are the n=odd members

Maier, John Paul

215

Crystal structure of 1-methyl-3-[2,2,2-tri­fluoro-1-(1-methyl-1H-indol-3-yl)-1-phenyl­eth­yl]-1H-indole  

PubMed Central

The title compound, C26H21F3N2, was prepared by the palladium-catalysed reaction of (2,2,2-tri­fluoro­eth­yl)benzene with 1-methyl-1H-indole. The dihedral angle between the planes of the indole-ring systems is 52.13?(6)° and the N-methyl groups point away from each other. Three short intra­molecular C—H?F contacts are observed. PMID:25484800

Liu, Xian-Rong; Zhou, Yan-Ling

2014-01-01

216

Atmospheric chemistry of perfluorobutenes (CF 3CF dbnd CFCF 3 and CF 3CF 2CF dbnd CF 2): Kinetics and mechanisms of reactions with OH radicals and chlorine atoms, IR spectra, global warming potentials, and oxidation to perfluorocarboxylic acids  

NASA Astrophysics Data System (ADS)

Relative rate techniques were used to determine k(Cl + CF 3CF dbnd CFCF 3) = (7.27 ± 0.88) × 10 -12, k(Cl + CF 3CF 2CF dbnd CF 2) = (1.79 ± 0.41) × 10 -11, k(OH + CF 3CF dbnd CFCF 3) = (4.82 ± 1.15) × 10 -13, and k(OH + CF 3CF 2CF dbnd CF 2) = (1.94 ± 0.27) × 10 -12 cm 3 molecule -1 s -1 in 700 Torr of air or N 2 diluent at 296 K. The chlorine atom- and OH radical-initiated oxidation of CF 3CF dbnd CFCF 3 in 700 Torr of air gives CF 3C(O)F in molar yields of 196 ± 11 and 218 ± 20%, respectively. Chlorine atom-initiated oxidation of CF 3CF 2CF dbnd CF 2 gives molar yields of 97 ± 9% CF 3CF 2C(O)F and 97 ± 9% COF 2. OH radical-initiated oxidation of CF 3CF 2CF dbnd CF 2 gives molar yields of 110 ± 15% CF 3CF 2C(O)F and 99 ± 8% COF 2. The atmospheric fate of CF 3CF 2C(O)F and CF 3C(O)F is hydrolysis to give CF 3CF 2C(O)OH and CF 3C(O)OH. The atmospheric lifetimes of CF 3CF dbnd CFCF 3 and CF 3CF 2CF dbnd CF 2 are determined by reaction with OH radicals and are approximately 24 and 6 days, respectively. The contribution of CF 3CF dbnd CFCF 3 and CF 3CF 2CF dbnd CF 2 to radiative forcing of climate change will be negligible.

Young, Cora J.; Hurley, Michael D.; Wallington, Timothy J.; Mabury, Scott A.

217

Le IR, c'est mort. Vive le IR  

E-print Network

The institutional repository is dead -- long live the institutional repository! Despite their rocky beginnings, IRs are finally finding their niche and surging forward. What were their initial mistakes, and how can further missteps be avoided? How...

Salo, Dorothea

2008-07-31

218

1H and 13C assignments of two new macrocyclic lactones isolated from Streptomyces sp. 211726 and revised assignments of azalomycins F3a, F4a and F5a.  

PubMed

Azalomycin F(4a) 2-ethylpentyl ester (1) and Azalomycin F(5a) 2-ethylpentyl ester (2), two new macrocyclic lactones, along with three known compounds of Azalomycins F(3a) (3), F(4a) (4) and F(5a) (5), were identified from metabolites of Streptomyces sp. 211726 isolated from mangrove rhizosphere soil. The complete (1)H and (13)C assignments of these compounds were achieved by using (1)H, (13)C, DEPT, HSQC, (1)H-(1)H COSY and HMBC spectra, and the relative stereochemistry of 5 was first elucidated on the basis of proton-proton coupling constants, NOESY and IR spectra. Moreover, some errors in the (1)H and (13)C assignments published of 3, 4 and 5 were found and revised. 1 and 2 were active against Candida albicans, and exhibited moderate cytotoxicity against HCT-116 cell line. PMID:21086419

Yuan, Ganjun; Lin, Haipeng; Wang, Cheng; Hong, Kui; Liu, Yue; Li, Jia

2011-01-01

219

Gasoline analysis by 1H nuclear magnetic resonance spectroscopy  

Microsoft Academic Search

High-resolution proton nuclear magnetic resonance (1H n.m.r.) spectroscopy allows the rapid and exact quantitative determination of the composition and quality of gasolines. For this study about 140 gasolines from Austrian filling stations were analysed. The amounts of methanol, methyl tert-butyl ether (MTBE), benzene and aromatics were determined quantitatively using an internal standard. These results were compared with data obtained by

Reinhard Meusinger

1996-01-01

220

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ir4.rutgers.edu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Information Exchange  

E-print Network

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ir4.rutgers.edu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Information Exchange pg 2 10/09 The November 2008 IR-4 Newsletter reported on "Progress on GMUS Action Items". The article focused on regulatory capacity building workshops, where IR-4's Biopesticide & Organic Support

Cotty, Peter J.

221

Stereoselective Synthesis of Hexahydro-1H-spiro[isoquinoline-4,4'-pyran] Scaffolds through an Intramolecular Prins Cascade Process.  

PubMed

A novel tandem cyclization strategy has been developed for the synthesis of hexahydro-1H-spiro[isoquinoline-4,4'-pyran] derivatives through the condensation of 3-((benzylamino)methyl)but-3-en-1-ol with aldehydes using BF3·OEt2. The reaction proceeds in a highly stereoselective manner, leading to a single diastereoisomer. This approach is a simple and efficient alternative for the synthesis of pharmacologically important spiroisoquinoline scaffolds. PMID:25415448

Subba Reddy, B V; Medaboina, Durgaprasad; Sridhar, B

2014-12-01

222

Benzimidazoles derivatives with (2-{6-Chloro-5-nitro-1-(2-(1H-tetrazol-5-yl) biphenyl- 4-ylmethyl) 1H-benzoimidazol-2-yl}-phenyl)-(substituted-benzylidene)-amine with potential angiotensin II receptor antagonists as antihypertensive activity  

Microsoft Academic Search

In this study we have synthesized some Benzimidazole derivatives (2-{6- Chloro-5-nitro-1-(2-(1H-tetrazol-5-yl) biphenyl-4-ylmethyl) 1H- benzoimidazol-2-yl}-phenyl)-(Substituted-benzylidene)-amine and screened for their antihypertensive activity. 4-chloro-o-Phenylenediamine was condensed with anthranilic acid in presence of Polyphosphoric acid and different aryl aldehydes compounds with biphenyl tetrazole ring. The presence of specific functional group were analysed by IR spectroscopy, The determination of structure for the synthesized compounds by

Mukesh C. Sharma; Dharm V. Kohli; Smita Sharma

2010-01-01

223

Levels of two-particle and gamma bands in 192Ir  

NASA Astrophysics Data System (ADS)

Level scheme of the transitional doubly odd nucleus 192Ir is analysed in detail up to about 530 keV energy using earlier published experimental data of neutron capture and particle transfer reactions. A number of new levels are proposed. Obtained 192Ir level scheme is interpreted in terms of particle-plus-rotor coupling model. It is shown that the long-lived 241 year isomer of 192Ir has spin-parity 11-, just like the analogous states in neighbouring 190,194Ir.

Balodis, M.; Krasta, T.

2015-01-01

224

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. PMID:25452862

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

2014-01-01

225

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

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

226

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

227

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

228

Crystal structure of 1H,1?H-[2,2?-biimid­azol]-3-ium hydrogen tartrate hemi­hydrate  

PubMed Central

In the crystal of the title hydrated salt, C6H7N4 +·C4H5O6 ?·0.5H2O, the bi­imidazole monocation, 1H,1?H-[2,2?-biimidazol]-3-ium, is hydrogen bonded, via N—H?O, O—H?O and O—H?N hydrogen bonds, to the hydrogen tartrate anion and the water mol­ecule, which is located on a twofold rotation axis, forming sheets parallel to (001). The sheets are linked via C—H?O hydrogen bonds, forming a three-dimensional structure. There are also C=O?? inter­actions present [O?? distances are 3.00?(9) and 3.21?(7)?Å], involving the carbonyl O atoms and the imidazolium ring, which may help to consolidate the structure. In the cation, the dihedral angle between the rings is 11.6?(2)°. PMID:25484840

Gao, Xiao-Li; Bian, Li-Fang; Guo, Shao-Wei

2014-01-01

229

Integrated uncooled array IR sensors  

Microsoft Academic Search

Technologies enabling low-dissipation designs for uncooled array IR sensors are offered. The technique involves the etching of special buffer layers from under a 1-micrometers membrane followed by deposition of an IR-sensitive film and electrode structure. The electrical and physical properties of plumbum-zirconate-titanate, barium titanate, tetraaminodiphenyl, polyvinylidene fluoride pyroelectric films are compared. A circuit for sensing pyroelectric signals in a CCD

Eugeny P. Pevtsov; Eugeny G. Elkin; Marina A. Pospelova

1997-01-01

230

Formation of octahedral iridium(III) dihydrides from the reaction of ortho-chelated aryliridium(I) compounds with dihydrogen  

SciTech Connect

The reaction of Ir/sup I/(CH/sub 2/NMe/sub 2/)-2-R/sup 1/-4-R/sup 2/-6)(COD) (COD = cyclooacta-1,5-diene) with dihydrogen in CD/sub 2/Cl/sub 2/ was monitored by /sup 1/H NMR. At -20/sup 0/C quantitative formation of the novel dihydride complexes Ir/sup III/H/sub 2/(C/sub 6/H/sub 2/(CH/sub 2/NMe/sub 2/)-2-R/sup 1/-4-R/sup 2/-6)(COD) (R/sup 1/ = H, R/sup 2/ = CH/sub 2/NMe/sub 2/ (10), Me (11); R/sup 2/ = H, R/sup 1/ = H (12), Me (13), CH/sub 2/NMe/sub 2/ (14); R/sup 1/ = R/sup 2/ = CH/sub 2/NMe/sub 2/ (15)) occurs. Further reactions, the type of which depends on the bulkiness of the R/sup 1/ and R/sup 2/ groups, occur when these solutions are warmed to 0/sup 0/C. Complexes 12-14 (R/sup 2/ = H) lose H/sub 2/ to re-form Ir/sup I/(C/sub 6/H/sub 3/(CH/sub 2/NMe/sub 2/)-2-R/sup 1/-4)(COD). In contrast, complexes 10, 11, and 15 (R/sup 2/ = alkyl) react further by means of C(aryl)-H reductive elimination. For complex 15 (R/sup 1/ = CH/sub 2/NMe/sub 2/) this results in quantitative formation of 1,3,5-(Me/sub 2/NCH/sub 2/)/sub 3/C/sub 6/H/sub 3/ and IrH(COD). In Ir/sup III/H/sub 2/(C/sub 6/H/sub 3/(CH/sub 2/NMe/sub 2/)-2-R-6)(COD) (R = alkyl (10 and 11)), C(aryl)-H reductive elimination is followed by re-addition of another C(aryl)-H bond, which upon subsequent reductive elimination of H/sub 2/, yields the rearranged iridium(I) complexes Ir/sup I/(C/sub 6/H/sub 3/(CH/sub 2/NMe/sub 2/)-2-R-4)(COD). Since the rearrangement of Ir/sup I/(C/sub 6/H/sub 3/-(CH/sub 2/NMe/sub 2/)-2-R-6)(COD) to Ir/sup I/(C/sub 6/H/sub 3/(CH/sub 2/NMe/sub 2/)-2-R-4)(COD) can also be induced thermally at 60/sup 0/C, it is therefore being catalyzed by dihydrogen at 0/sup 0/C. None of these reactions with dihydrogen is attended by hydrogenation of the COD ligand.

van der Zeijden, A.A.H.; van Koten, G.; Lujik, R.; Grove, D.M.

1988-07-01

231

Synthesis and x-ray structural characterization of binuclear iridium(I) and rhodium(I) hydroxypyridinate complexes. 1. Complete assignment of the /sup 1/H NMR spectra by two-dimensional and NOE techniques. The nature of inside and outside /sup 1/H chemical shift differences  

SciTech Connect

Six new d/sup 8/-d/sup 8/ complexes, (Ir(COD)(..mu..-hp))/sub 2/, (Ir(COD)(..mu..-mhp))/sub 2/, (Ir(COD)(..mu..-chp))/sub 2/, (Ir(COD)(..mu..-2hq))/sub 2/, (Rh(COD)(..mu..-hp))/sub 2/, and (Rh(COD)(..mu..-mhp))/sub 2/ (hp = 2-hydroxyphridinate, mhp = 6-methyl-2-hydroxypyridinate, chp = 6-chloro-2-hydroxypyridinate, 2hq = 2-hydroxyquinolate, COD = 1,5-cyclooctadiene), were synthesized and characterized by /sup 1/H NMR, /sup 13/C NMR, and IR spectroscopy and FAB mass spectrometry. X-ray crystallographic analyses of the isostructural (M(COD)(..mu..-mhp))/sub 2/ (M = Ir and Rh) complexes confirmed the binuclear nature of the complexes. The complete assignment of the /sup 1/H NMR spectrum of (Ir(COD)(..mu..-hp))/sub 2/ (and by analogy, the spectra of the other five complexes) was carried out with selective decoupling, nuclear Overhauser effect (NOE), and two-dimensional NMR techniques. The NOE observed between hp proton H5 and COD proton H15 allowed the precise assignment of all 12 COD resonances. Olefinic proton H12 (trans to N and outside) resonates downfield of olefinic proton H11 (trans to N and inside). Olefininc proton H15 (trans to O and outside) resonates upfield of olefinic proton H16 (trans to O and inside). The endo methylene protons resonate upfield of the exo methylene protons. The inside/outside chemical shift differences observed for these compounds are ascribed to steric and magnetic anisotropy effects. The crystallographic data are presented. The molecular structure of the complexes is discussed in detail. 39 references, 5 figures, 9 tables.

Rodman, G.S.; Mann, K.R.

1988-09-21

232

Development of novel Asf1-H3/H4 inhibitors.  

PubMed

The histone chaperone anti-silencing function 1 (Asf1) has emerged as a promising target for therapeutic intervention for multiple cancers (Cell2006, 127, 458). Asf1 is involved in the packaging of the eukaryotic genome into chromatin, which is essential for normal growth, development, and differentiation, as this regulates all nuclear processes that use DNA as a substrate. Starting from a collection of HTS leads, we identified a series of N-acyl hydrazones as novel inhibitors of the Asf-histone H3/H4 interaction. These compounds represent the first example of inhibitors capable of disrupting the Asf1-H3/H4 complex. PMID:25582598

Miknis, Greg F; Stevens, Sarah J; Smith, Luke E; Ostrov, David A; Churchill, Mair E A

2015-02-15

233

Serial 1H-MRS in GM2 gangliosidoses  

Microsoft Academic Search

GM2 gangliosidoses are a group of neuronal storage disorders caused by deficiency in the lysosomal enzyme hexosaminidase A.\\u000a Clinically, the disease is marked by a relentless encephalopathy. Proton magnetic resonance spectroscopy (1H-MRS) provides\\u000a in-vivo measurement of various brain metabolites including N-acetyl aspartate+N-acetyl aspartate glutamate (NAA), myo-inositol\\u000a (mI), choline (Cho) and creatine (Cr). The NAA represents neuronal integrity while elevation in

Mitra Assadi; Susan Baseman; Christopher Janson; Dah-Jyuu Wang; Larissa Bilaniuk; Paola Leone

2008-01-01

234

60 MHz (1)H NMR spectroscopy for the analysis of edible oils.  

PubMed

We report the first results from a new 60 MHz (1)H nuclear magnetic resonance (NMR) bench-top spectrometer, Pulsar, in a study simulating the adulteration of olive oil with hazelnut oil. There were qualitative differences between spectra from the two oil types. A single internal ratio of two isolated groups of peaks could detect hazelnut oil in olive oil at the level of ?13%w/w, whereas a whole-spectrum chemometric approach brought the limit of detection down to 11.2%w/w for a set of independent test samples. The Pulsar's performance was compared to that of Fourier transform infrared (FTIR) spectroscopy. The Pulsar delivered comparable sensitivity and improved specificity, making it a superior screening tool. We also mapped NMR onto FTIR spectra using a correlation-matrix approach. Interpretation of this heat-map combined with the established annotations of the NMR spectra suggested a hitherto undocumented feature in the IR spectrum at ?1130 cm(-1), attributable to a double-bond vibration. PMID:24850979

Parker, T; Limer, E; Watson, A D; Defernez, M; Williamson, D; Kemsley, E Kate

2014-05-01

235

60 MHz 1H NMR spectroscopy for the analysis of edible oils?  

PubMed Central

We report the first results from a new 60 MHz 1H nuclear magnetic resonance (NMR) bench-top spectrometer, Pulsar, in a study simulating the adulteration of olive oil with hazelnut oil. There were qualitative differences between spectra from the two oil types. A single internal ratio of two isolated groups of peaks could detect hazelnut oil in olive oil at the level of ?13%w/w, whereas a whole-spectrum chemometric approach brought the limit of detection down to 11.2%w/w for a set of independent test samples. The Pulsar’s performance was compared to that of Fourier transform infrared (FTIR) spectroscopy. The Pulsar delivered comparable sensitivity and improved specificity, making it a superior screening tool. We also mapped NMR onto FTIR spectra using a correlation-matrix approach. Interpretation of this heat-map combined with the established annotations of the NMR spectra suggested a hitherto undocumented feature in the IR spectrum at ?1130 cm?1, attributable to a double-bond vibration. PMID:24850979

Parker, T.; Limer, E.; Watson, A.D.; Defernez, M.; Williamson, D.; Kemsley, E. Kate

2014-01-01

236

An iron-based green approach to 1-h production of single-layer graphene oxide.  

PubMed

As a reliable and scalable precursor of graphene, graphene oxide (GO) is of great importance. However, the environmentally hazardous heavy metals and poisonous gases, explosion risk and long reaction times involved in the current synthesis methods of GO increase the production costs and hinder its real applications. Here we report an iron-based green strategy for the production of single-layer GO in 1?h. Using the strong oxidant K2FeO4, our approach not only avoids the introduction of polluting heavy metals and toxic gases in preparation and products but also enables the recycling of sulphuric acid, eliminating pollution. Our dried GO powder is highly soluble in water, in which it forms liquid crystals capable of being processed into macroscopic graphene fibres, films and aerogels. This green, safe, highly efficient and ultralow-cost approach paves the way to large-scale commercial applications of graphene. PMID:25607686

Peng, Li; Xu, Zhen; Liu, Zheng; Wei, Yangyang; Sun, Haiyan; Li, Zheng; Zhao, Xiaoli; Gao, Chao

2015-01-01

237

An iron-based green approach to 1-h production of single-layer graphene oxide  

PubMed Central

As a reliable and scalable precursor of graphene, graphene oxide (GO) is of great importance. However, the environmentally hazardous heavy metals and poisonous gases, explosion risk and long reaction times involved in the current synthesis methods of GO increase the production costs and hinder its real applications. Here we report an iron-based green strategy for the production of single-layer GO in 1?h. Using the strong oxidant K2FeO4, our approach not only avoids the introduction of polluting heavy metals and toxic gases in preparation and products but also enables the recycling of sulphuric acid, eliminating pollution. Our dried GO powder is highly soluble in water, in which it forms liquid crystals capable of being processed into macroscopic graphene fibres, films and aerogels. This green, safe, highly efficient and ultralow-cost approach paves the way to large-scale commercial applications of graphene. PMID:25607686

Peng, Li; Xu, Zhen; Liu, Zheng; Wei, Yangyang; Sun, Haiyan; Li, Zheng; Zhao, Xiaoli; Gao, Chao

2015-01-01

238

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

PubMed

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

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

2013-10-15

239

Synthesis, crystal structure, and 1 H NMR spectra of a chloride-bridged chain complex of dinuclear ruthenium(II,III) 3,4,5-tri(ethoxy- d 5 )benzoate  

Microsoft Academic Search

Deuterated dinuclear ruthenium(II,III) 3,4,5-tri(ethoxy-d\\u000a 5)benzoate, [Ru2{3,4,5-(C2D5O)3C6H2-COO}4Cl]\\u000a n\\u000a , was synthesized by a reaction of [Ru2(C2H5COO)4Cl]\\u000a n\\u000a and 3,4,5-tri(ethoxy-d\\u000a 5)benzoic acid and characterized by single-crystal X-ray analysis as well as IR, UV-VIS, and 1H NMR spectra, and compared with those of the undeuterated complex [Ru2{3,4,5-(C2H5O)3C6H2COO}4Cl]\\u000a n\\u000a . Single-crystal X-ray analysis showed that chloride ligands bridge the dinuclear ruthenium(II,III) units at the

Hideaki Ishida; Makoto Handa; Takahisa Ikeue; Jun Taguchi; Masahiro Mikuriya

2010-01-01

240

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

241

Facile One?Pot Synthesis of 3,4?Dihydropyrimidin?2(1H)?one Catalyzed by Zn(NH2SO3)2  

Microsoft Academic Search

An efficient synthesis of 3,4?dihydropyrimidin?2(1H)?ones (DHPMS) from aromatic aldehydes, ??keto ester, and urea (or thiourea) in refluxing ethanol using zinc sulfamate as a catalyst is first described here. Compared to the classical Biginelli reaction, this new method consistently has the advantages of good yields (76–96%), short reaction time (2–5 h), no corrosion of equipment, ease of manipulation, and low?cost catalyst.

Min Zhang

2006-01-01

242

Sulfated Tin Oxide: A Reusable and Highly Efficient Heterogeneous Catalyst for the Synthesis of 2,4,5-Triaryl-1H-imidazole Derivatives  

Microsoft Academic Search

One-pot, three-component condensation of benzil\\/benzoin, substituted aromatic aldehydes, and ammonium acetate in an ethanol–water (1:1, v\\/v) solvent system using sulfated tin oxide catalyst under reflux condition afforded corresponding 2,4,5-triaryl-1H-imidazoles in excellent yield. The remarkable advantages offered by this method include green and reusable catalyst, mild reaction conditions, fast reaction rate, and excellent yield of products. This novel methodology maintains atom

Satish A. Dake; Mahesh B. Khedkar; Ghanshyam S. Irmale; Suhas J. Ukalgaonkar; Vinod V. Thorat; Suhas A. Shintre; Rajendra P. Pawar

2012-01-01

243

Sulfated Tin Oxide: A Reusable and Highly Efficient Heterogeneous Catalyst for the Synthesis of 2,4,5-triaryl-1H-imidazole Derivatives  

Microsoft Academic Search

One-pot three component condensation of benzil\\/benzoin, substituted aromatic aldehydes and ammonium acetate in ethanol: water (1:1, v\\/v) solvent system using sulfated tin oxide catalyst under reflux condition afforded corresponding 2,4,5-triaryl-1H-imidazoles in excellent yield. The remarkable advantage offered by this method is green & reusable catalyst, mild reaction conditions, fast reaction rate and excellent yield of products. This novel methodology maintains

Satish A. Dake; Mahesh B. Khedkar; Ghanshyam S. Irmale; Suhas J. Ukalgaonkar; Vinod V. Thorat; Suhas A. Shintre; Rajendra P. Pawar

2011-01-01

244

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 be gained Ralf Siebenmorgen Why? pwv, T, aerosols IR projects: DomeC and elsewhere Science cases Conclusion: my favoured modes (thermal) IR := 2-24µm = K,L,M,N,Q #12;Ralf Siebenmorgen IR instrument from

Siebenmorgen, Ralf

245

(1)H NMR and (1)H-(13)C HSQC surface characterization of chitosan-chitin sheath-core nanowhiskers.  

PubMed

Surface deacetylation of chitin nanowhiskers (CtNWs) to chitosan-sheath/chitin-core nanowhiskers (CsNWs) was successfully monitored by liquid-state high-resolution NMR of colloidal suspensions of these never-dried nanowhiskers. CtNWs were derived from acid hydrolysis (3N HCl, 30mL/g, 90min, 104°C) of chitin at 65% yield and 86% CrI. Deacetylation (50% NaOH, 48h, 50°C) of CtNWs generated CsNWs with unchanged nanowhisker morphology and overall length and width dimensions, but a reduced CrI of 54%. Successful step-wise exchanging the aqueous media with acetone, then D2O prevented agglomeration of nanowhiskers and enabled NMR detection of individual nanowhiskers. The crystalline structure of CtNWs and CsNWs provided different chemical environments for the glucosamine hydrogen atom H2, splitting the NMR signals into 2 peaks (? 3.0 and ? 3.35ppm) which differed from that reported for soluble chitosan (? 3.2ppm). Besides, (1)H-(13)C HSQC was only possible for CsNWs indicating the NMR phenomenon observed to represent that of the surfaces where the outer layers were highly mobile and less crystalline. The degree of acetylation at the surfaces was determined from (1)H NMR data to be 56% and 9% for CtNWs and CsNWs, respectively. PMID:25843833

Pereira, Antonio G B; Muniz, Edvani C; Hsieh, You-Lo

2015-06-01

246

Synthesis and properties of photochromic biindenylidenedione derivatives containing thiophene groups, and new insights into the reaction of 2,2?-biindanylidene-1,1?,3,3?-tetraone with Grignard reagent  

NASA Astrophysics Data System (ADS)

Three indenone derivatives ( 1: 2-[3'-hydroxy-3'-(2-thienyl)indanone-2'-yl]-3-(2-thienyl)indenone; 2: trans- anti-3,3'-(2-thienyl)-3,3'-dihydroxy-[2,2'-bi-1H-indene]-1,1'-dione and 3: trans- syn-3,3'-(2-thienyl)-3,3'-dihydroxy-[2,2'-bi-1H-indene]-1,1'-dione) were obtained in a one-pot reaction of 2,2'-biindanylidene-1,1',3,3'-tetraone with 2-thienylmagnesium bromide. Their structures were characterized by means of IR, 1H NMR, MS, elemental analysis, and X-ray crystallography. The photochromic and photo-induced radical behaviors of these compounds were investigated by means of solid UV-vis spectroscopy and electron spin resonance (ESR) spectroscopy. The results show that compounds 2 and 3 exhibit photochromism in the solid state, whereas compound 1 does not. The relationship between the crystal structures and photochemical properties is also discussed. Based on the formation and product distribution of compounds 1, 2, and 3, a plausible pathway is suggested for the reaction of 2,2'-biindanylidene-1,1',3,3'-tetraone with 2-thienylmagnesium bromide. The findings obtained in this study also provide new insights into the addition-oxidation mechanism for the reaction of 2,2'-biindanylidene-1,1',3,3'-tetraone with Grignard reagent.

Liu, Juyan; Han, Jie; Song, Zhiyi; Wei, Yongheng; Pang, Meili; Meng, Jiben

2008-11-01

247

Theoretical studies of Ir5Th and Ir5Ce nanoscale precipitates in Ir  

SciTech Connect

Experimentally, it is known that very small amounts of thorium and/or cerium added to iridium metal form a precipitate, Ir5Th / Ir5Ce, which improves the high temperature mechanical properties of the resulting alloys. We demonstrate that there are low-energy configurations for nano-scale precipitates of these phases in Ir, and that these coherent arrangements may assist in producing improved mechanical properties. One precipitate/matrix orientation gives a particularly low interfacial energy, and a low lattice misfit. Nanolayer precipitates with this orientation are found to be likely to form, with little driving force to coarsen. The predicted morphology of the precipitates and their orientation with the matrix phase provide a potential experiment that could be used to test these predictions.

Morris, James R [ORNL] [ORNL; Averill, Frank [ORNL] [ORNL; Cooper, Valentino R [ORNL] [ORNL

2014-01-01

248

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

249

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

ERIC Educational Resources Information Center

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

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

2012-01-01

250

Concealing compensation from the IRS.  

PubMed

Tougher reporting requirements from the Internal Revenue Service are prompting some not-for-profit hospitals to seek ways to hide compensation arrangements from the public and the media. Critics believe those tactics could get hospitals in hot water with the law, especially now that the IRS has launched a new, aggressive auditing offensive. PMID:10108763

Burda, D; Greene, J

1991-01-28

251

IrYdium Project, The  

NSDL National Science Digital Library

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

252

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...

253

Spitzer IRS Analysis of Neptune  

Microsoft Academic Search

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

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

2008-01-01

254

IR Variability of Eta Carinae  

NASA Astrophysics Data System (ADS)

Every 5.5 years, ? Carinae experiences a dramatic ``spectroscopic event'' when high-excitation lines in its UV, optical, and IR spectrum disappear, and its hard X-ray and radio continuum flux crash. This periodicity has been attributed to an eccentric binary system with a shell ejection occurring at periastron, and the next periastron event will occur at the very end of 2008. In addition, ? Car shows long term changes as it is still recovering from its giant 19th century outburst. Both types of variability are directly linked to the current mass-loss rate and dust formation in its wind. Mid-IR images and spectra with T-ReCS provide a direct measure of changes in the current bolometric luminosity and a direct measure of the massw in dust formation episodes that may occur at periastron in the colliding wind shock. Near-IR emission lines trace related changes in the post-event wind and ionization changes in the circumstellar environment needed to test specific models for the cause of ? Car's variability as it recovers from its recent ``event''. High resolution near-IR spectra with Phoenix will continue the important work of HST/STIS, investigating changes in the direct and reflected spectrum of the stellar wind, and ionization changes in the nebula.

Smith, Nathan

2008-02-01

255

IR Variability of Eta Carinae  

NASA Astrophysics Data System (ADS)

Every 5.5 years, ? Carinae experiences a dramatic ``spectroscopic event'' when high-excitation lines in its UV, optical, and IR spectrum disappear, and its hard X-ray and radio continuum flux crash. This periodicity has been attributed to an eccentric binary system with a shell ejection occurring at periastron. In addition, ? Car shows long term changes as it is still recovering from its giant 19th century outburst. Both types of variability are directly linked to the current mass-loss rate and dust formation in its wind. Mid-IR images and spectra with T-ReCS provide a direct measure of changes in the current bolometric luminosity and trace dust formation episodes. This will provide a direct measurement of the mass ejected. Near-IR emission lines trace related changes in the post-event wind and ionization changes in the circumstellar environment needed to test specific models for the cause of ? Car's variability as it recovers from its recent ``event''. High resolution near-IR spectra with GNIRS will continue the important work of HST/STIS, investigating changes in the direct and reflected spectrum of the stellar wind, and ionization changes in the nebula.

Smith, Nathan

2007-02-01

256

IR-UV photochemistry of protein-nucleic acid systems  

SciTech Connect

UV light has often been used to induce the formation of covalent bonds between DNA (or RNA) and tightly-bound protein molecules. However, the internal photoreactions of nucleic acids and proteins limit the yield and complicate the analysis of intermolecular crosslinks. In an ongoing search for improved reaction specificity or new photoreactions in these systems, we have employed UV photons from a Nd:YAG-pumped dye laser and mid-IR photons from the Vanderbilt FEL. Having crosslinked several protein-nucleic acid systems with nanosecond UV laser pulses, we are currently studying the effect of various IR wavelengths on a model system (gene 32 protein and poly[dT]). We have found that irradiation with sufficiently intense FEL macropulses creates an altered form of gene 32 protein which was not observed with UV-only irradiation. The electrophoretic nobility of the product is consistent with the formation of a specific protein-protein crosslink. No evidence of the non-specific protein damage typically induced by UV light is found. The yield of the new photoproduct is apparently enhanced by exposure to FEL macropulses which are synchronized with UV laser pulses. With ideal exposure parameters, the two-color reaction effectively competes with UV-only reactions. Experiments designed to determine the reaction mechanism and to demonstrate FEL-induced reactions in other protein-nucleic acid systems are currently underway.

Kozub, J.; Edwards, G. [Vanderbilt Univ., Nashville, TN (United States)

1995-12-31

257

Oxyfunctionalization with Cp*Ir(III)(NHC)(Me)(Cl) with O2: Identification of a Rare Bimetallic Ir(IV) ?-Oxo Intermediate.  

PubMed

Methanol formation from [Cp*Ir(III)(NHC)Me(CD2Cl2)](+) occurs quantitatively at room temperature with air (O2) as the oxidant and ethanol as a proton source. A rare example of a diiridium bimetallic complex, [(Cp*Ir(NHC)Me)2(?-O)][(BAr(F)4)2], 3, was isolated and shown to be an intermediate in this reaction. The electronic absorption spectrum of 3 features a broad observation at ?660 nm, which is primarily responsible for its blue color. In addition, 3 is diamagnetic and can be characterized by NMR spectroscopy. Complex 3 was also characterized by X-ray crystallography and contains an Ir(IV)-O-Ir(IV) core in which two d(5) Ir(IV) centers are bridged by an oxo ligand. DFT and MCSCF calculations reveal several important features of the electronic structure of 3, most notably, that the ?-oxo bridge facilitates communication between the two Ir centers, and ?/? mixing yields a nonlinear arrangement of the ?-oxo core (Ir-O-Ir ? 150°) to facilitate oxygen atom transfer. The formation of 3 results from an Ir oxo/oxyl intermediate that may be described by two competing bonding models, which are close in energy and have formal Ir-O bond orders of 2 but differ markedly in their electronic structures. The radical traps TEMPO and 1,4-cyclohexadiene do not inhibit the formation of 3; however, methanol formation from 3 is inhibited by TEMPO. Isotope labeling studies confirmed the origin of the methyl group in the methanol product is the iridium-methyl bond in the [Cp*Ir(NHC)Me(CD2Cl2)][BAr(F)4] starting material. Isolation of the diiridium-containing product [(Cp*Ir(NHC)Cl)2][(BAr(F)4)2], 4, in high yields at the end of the reaction suggests that the Cp* and NHC ligands remain bound to the iridium and are not significantly degraded under reaction conditions. PMID:25700811

Lehman, Matthew C; Pahls, Dale R; Meredith, Joseph M; Sommer, Roger D; Heinekey, D Michael; Cundari, Thomas R; Ison, Elon A

2015-03-18

258

Synthesis, Structure, and Reactivity of O-Donor Ir(III) Complexes: C-H Activation Studies with Benzene  

E-print Network

with Benzene Gaurav Bhalla, Xiang Yang Liu, Jonas Oxgaard, William A. Goddard, III, and Roy A. Periana. All the R-Ir-Py complexes undergo quantitative, intermolecular CH activation reactions with benzene to benzene to generate a discrete benzene complex, cis-R-Ir-PhH; and (D) rapid C-H cleavage. Kinetic isotope

Goddard III, William A.

259

Collaborative Student Laboratory Exercise Using FT-IR Spectroscopy for the Kinetics Study of a Biotin Analogue  

ERIC Educational Resources Information Center

The synthesis of N-methoxycarbonyl-2-imidazolidone, an analogue of biotin, was conducted by organic chemistry students and confirmed using FT-IR and H NMR. Spectroscopy students used FT-IR to measure the rate of hydrolysis of the product and determined the rate constant for the reaction using the integrated rate law. From the magnitude of the rate…

Leong, Jhaque; Ackroyd, Nathan C.; Ho, Karen

2014-01-01

260

An Ir(IV)-containing polyoxometalate.  

PubMed

[HIr(IV)W6O24](7-), representing the first Ir-containing Anderson-Evans-type polyanion and the first structurally characterized Ir(IV)-based polyoxometalate, has been isolated as its hydrated sodium salt and characterized by single-crystal X-ray diffraction, mass spectrometry, and IR, UV-Vis and EPR spectroscopy. Cyclic voltammetry indicates that the Ir(IV) ions in [HIrW6O24](7-) can undergo reversible one-electron reduction and oxidation, resulting in Ir(III) and Ir(V) derivatives. PMID:25469664

Adonin, Sergey A; Izarova, Natalya V; Besson, Claire; Abramov, Pavel A; Santiago-Schübel, Beatrix; Kögerler, Paul; Fedin, Vladimir P; Sokolov, Maxim N

2015-01-25

261

Chemometric prediction of alginate monomer composition: A comparative spectroscopic study using IR, Raman, NIR and NMR  

Microsoft Academic Search

The potential of using infrared (IR), Raman and near infrared (NIR) spectroscopy combined with chemometrics for reliable and rapid determination of the ratio of mannuronic and guluronic acid (M\\/G ratio) in commercial sodium alginate powders has been investigated. The reference method for quantification of the M\\/G ratio was solution-state 1H nuclear magnetic resonance (NMR) spectroscopy. For a set of 100

Tina Salomonsen; Henrik Max Jensen; Dorthe Stenbæk; Søren Balling Engelsen

2008-01-01

262

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

263

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

264

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

265

Phosphonic acid functionalized ordered mesoporous material: a new and ecofriendly catalyst for one-pot multicomponent Biginelli reaction under solvent-free conditions.  

PubMed

We report a new ordered 2D hexagonal mesoporous organosilica material (PAFMS-1) bearing phosphonic acid functionality at the surface. This hybrid material showed high Brunauer-Emmett-Teller surface area (565 m(2) g(-1)) and ordered assembly of mesoporoes with an average pore diameter of ca. 2.1 nm. This novel hybrid mesoporous material has been synthesized via cocondensation of (triethoxysilyl)(propyliminomethyl)biphenylmethyl phosphoester (PEFOS) and tetraethyl orthosilicate (TEOS) in the presence of cationic surfactant cetyltrimethylammonium bromide (CTAB) at 373 K. The phosphoester-functionalized organosilane (PEFOS) precursor has been synthesized for the first time by a simple SN2 reaction followed by Suzuki coupling and a Mannich reaction. The material has been characterized by powder X-ray diffraction, N2 sorption, and transmission electron microscopy image analysis, whereas the presence of organic moieties (an aromatic biphenyl ring and an aliphatic side chain), phosphrous, and silicon in the pore wall of the material have been characterized by solid-state magic-angle-spinning NMR, X-ray photoelectron, and Fourier transform infrared (FT-IR) spectroscopic tools. Further, the surface acid strength of the hybrid material has been determined by FT-IR analysis of the samples via temperature-programmed pyridine adsorption studies. The material has been utilized as a reusable heterogeneous catalyst for the synthesis of biologically important and value added multifunctionalized 3,4-dihydropyridin-2-1H-(ones)/3,4-dihydropyridin-2-1H-(thiones) (DHPMs) through a multicomponent Biginelli condensation reaction under solvent-free conditions at 333 K. The phosphonic acid functionalized 2D hexagonal mesoporous material showed much higher catalytic activity in this multicomponent condensation reaction over sulfonic acid functionalized mesoporous silica (MCM-41-SO3H) bearing an aliphatic chain in the hybrid framework. PMID:24372168

Pramanik, Malay; Bhaumik, Asim

2014-01-22

266

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

267

Pd(II)-catalyzed ligand controlled synthesis of methyl 1-benzyl-1H-indole-3-carboxylates and bis(1-benzyl-1H-indol-3-yl)methanones.  

PubMed

A simple change of ligand and solvent allows controlled, effective switching between cyclization-carbonylation and cyclization-carbonylation-cyclization-coupling (CCC-coupling) reactions of 2-alkynylanilines catalyzed by palladium(II). The use of a [Pd(tfa)2(box)] catalyst in iPrOH afforded symmetrical ketones bearing two indoles in good yields; replacing the catalyst and solvent with Pd(tfa)2 and DMSO-MeOH led to the formation of methyl 1-benzyl-1H-indole-3-carboxylates in good yields. PMID:24802816

Shen, Rong; Kusakabe, Taichi; Takahashi, Keisuke; Kato, Keisuke

2014-07-14

268

1H NMR spectroscopic identification of a glue sniffing biomarker.  

PubMed

Organic solvent abuse typically involves sniffing organic solvents to experience the mind-altering conditions they induce. In Republic of Korea, organic solvent abuse is a serious social problem, especially among teenagers. Several studies have addressed the effects of organic solvent abuse on mind and body, but there are no simple methods by which such abuse can be positively identified. In this report, we describe a method for analyzing toluene metabolites (toluene is the main ingredient of glue) in glue-sniffers' urine using (1)H NMR spectroscopy. Toluene is a commonly used solvent in the rubber, paint, plastics, leather, printing, and chemical industries. Inhaled toluene is metabolized to hippuric acid in the liver and excreted in the urine. Hippuric acid is known as a good biomarker for biological monitoring of toluene exposure. We have scanned hippuric acid and other toluene metabolites by NMR spectroscopy and performed statistical multivariate analysis of the data. Based on this analysis, we sought to determine parameters by which glue-sniffing (toluene inhalation) behavior may be verified. We also demonstrate the use of a pattern recognition method for accurate and efficient analysis of NMR data. In comparison to conventional methods, such as mass spectroscopy coupled with liquid chromatography or gas chromatography, nuclear magnetic resonance spectroscopy has several advantages, including simple sample preparation, non-destructive sampling, accuracy, short acquisition time, and reproducibility in the determination of urinary hippuric acid. PMID:21316881

Kwon, Bobae; Kim, Siwon; Kim, Sosun; Lee, Dong-Kye; Park, Yu-Jin; Kim, Myung-Duck; Lee, Jae-Shin; Kim, Suhkmann

2011-06-15

269

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

270

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

271

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

272

Preliminary 1H NMR study on archaeological waterlogged wood.  

PubMed

Magnetic Resonance Relaxation (MRR) and Magnetic Resonance Imaging (MRI) are powerful tools to obtain detailed information on the pore space structure that one is unlikely to obtain in other ways. These techniques are particularly suitable for Cultural Heritage materials, because they use water 1H nuclei as a probe. Interaction with water is one of the main causes of deterioration of materials. Porous structure in wood, for example, favours the penetration of water, which can carry polluting substances and promote mould growth. A particular case is waterlogged wood from underwater discoveries and moist sites; in fact, these finds are very fragile because of chemical, physical and biological decay from the long contact with the water. When wood artefacts are brought to the surface and directly dried in air, there is the collapse of the cellular structures, and wood loses its original form and dimensions and cannot be used for study and museum exhibits. In this work we have undertaken the study of some wood finds coming from Ercolano's harbour by MRR and MRI under different conditions, and we have obtained a characterization of pore space in wood and images of the spatial distribution of the confined water in the wood. PMID:16485652

Maccotta, Antonella; Fantazzini, Paola; Garavaglia, Carla; Donato, Ines D; Perzia, Patrizia; Brai, Maria; Morreale, Filippa

2005-01-01

273

1H and 13C Solid-state NMR of Gossypium barbadense (Pima) Cotton  

Technology Transfer Automated Retrieval System (TEKTRAN)

The interaction of water with cellulose and its influence on the nuclear spin dynamics in G. barbadense (Pima) cotton were investigated by 1H and 13C solid-state NMR techniques. 1H spin diffusion results from a Goldman-Shen experiment indicate that the water is multilayered. 1H MAS experiments pro...

274

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

PubMed

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

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

2012-06-01

275

Antifungal activity of novel 5-carbonyl derivatives of 3-phenyl-3-(1H-imidazol-1-ylmethyl)-2-methylisoxazolidines.  

PubMed

The synthesis and antifungal activity of a series of novel 5-carbonyl derivatives of 3-phenyl-3-(1H-imidazol-1-ylmethyl)-2-methylisoxazolidines (4) are discussed. The preparation of the title compounds involved a 1,3-dipolar cycloaddition reaction of alpha-substituted ketonitrones with either acrylic esters, acrylamide or methyl vinyl ketone to furnish cis/trans-diastereomeric mixtures of the desired 5-carbonyl isoxazolidines 4. The anifungal activity was evaluated in vitro in solid agar cultures. Some of the compounds tested exerted moderate to potent activity against a wide variety of dermatophytes and yeast and systemic fungi. PMID:2610586

Bennett, G A; Mullen, G B; DeCory, T R; Maryniak, D M; Jones, W E; Mitchell, J T; Allen, S D; St Georgiev, V

1989-09-01

276

Approaches to the construction of substituted 4-amino-1H-pyrrol-2(5H)-ones.  

PubMed

Fully substituted 4-aminopyrrolones are easily accessed via simple routes starting from imines, ketones, or ?-bromophenyl acetonitriles. Imines were reacted with KCN/NH(4)Cl in aqueous ethanol to produce ?-arylamino benzyl cyanides. On the other hand, ketones were transformed to the desired ?-amino nitriles using a modified Strecker reaction. Then, ?-amino nitrile precursors were allowed to react with a suitable acyl halide to produce the corresponding amides. Further treatment of these amides with ethanolic KOH converted them to highly substituted 4-amino-1H-pyrrol-2(5H)-one derivatives in moderate to excellent yields. PMID:22663152

Zali-Boeini, Hassan; Mobin, Mehdi; Hajibabaei, Khadijeh; Ghani, Maryam

2012-07-01

277

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

278

Ab initio Hartree-Fock investigation of 1- H-pyrrolo[3,2- b]pyridine-3-yl acetic acid  

NASA Astrophysics Data System (ADS)

The potential energy surface of 1- H-pyrrolo[3,2- b]pyridine-3-yl acetic acid has been investigated via RIIF/6-31G* calculations. The stationary points and reaction paths for syn orientation of the COOH group were determined and are compared with those of the derivatives of 3-indole acetic acid, which act as plant growth hormones. 1- H-pyrrolo[3,2- b]pyridine-3-yl acetic acid forms a kinetically stable conformer with a strong intramolecular hydrogen bond, in which the COOH group is in anti orientation. The influence of this hydrogen bond on bond lengths and vibration frequencies is described.

Ramek, Michael; Tomi?, Sanja

2001-09-01

279

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

280

Concerning the transformations of Ti 3Ir alloy during high-energy ball-milling  

Microsoft Academic Search

Thermodynamically stable Ti3Ir with the Cr3Si (A15)-type crystal structure can gradually be transformed into a metastable Ti3Ir alloy with a bcc crystal structure by high-energy ball-milling for 12.5 h. The long-term ball-milling for up to 112 h, however, is accompanied by a solid-state reaction between Ti3Ir and the vial material leading to the formation of a nano-crystalline or amorphous MgZn2-type

V. P Balema; A. O Pecharsky; V. K Pecharsky

2000-01-01

281

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 production from selected wind farms, power measure- ments for all wind turbines in the area and numerical

282

Vista IR Camera: Conceptual Design  

Microsoft Academic Search

This paper describes the conceptual design for a near infrared camera for the Visible and Infrared Survey Telescope for Astronomy (VISTA). VISTA is a 4m class survey telescope that is being designed to perform pre-planned, ground-based astronomical surveys of the Southern sky from ESO's Cerro Paranal Observatory in Chile. The IR Surveys will be carried out in the J, H

Ian Egan; Eli Atad-Ettedgui; Mark M. Casali; Simon C. Craig; Maureen A. Ellis; Peter R. Hastings; David M. Henry; Ken Laidlaw; John Murray; Malcom Stewart; Will Sutherland

2002-01-01

283

Sixteen new IR laser dyes  

Microsoft Academic Search

Sixteen new IR laser dyes are reported. All lased successfully under excitation from a simple linear flashlamp of about 700-ns rise time. Untuned lasing wavelengths ranged from 810 to 972 nm. Laser output pulse energies from the four best of these dyes were 5-15 times greater than from diethylthiatricarbocyanine iodide (DTTC), with peak output of about 50 mJ obtained from

J. P. Webb; F. G. Webster; B. E. Plourde

1975-01-01

284

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.

285

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

286

Retro-prospective in IR optical detectors  

Microsoft Academic Search

This presentation looks back over this last twenty years, the French activity in IR detectors. Photon and thermal detectors, cooled and uncooled focal plane arrays are considered. Two specific experiences are described on Automation Home IR Systems and Earth horizon IR sensing for Space Applications. The discussion is focussed on low cost devices and perspectives which are to be open

Daniel Esteve; Francis Bony; Christophe Escriba; E. Campo; Jean-Yves Fourniols

2004-01-01

287

Synthesis and antimycobacterial activity of 3-aryl-, 3-cyclohexyl- and 3-heteroaryl- substituted-2-(1 H(2 H)-benzotriazol-1(2)-yl)prop-2-enenitriles, prop-2-enamides and propenoic acids. II  

Microsoft Academic Search

A series of 32 3-aryl-, 3-cyclohexyl-, and 3-heteroaryl-substituted-2-(1H(2H)-benzotriazol-1(2)-yl)-prop-2-enenitriles, prop-2-enamides and propenoic acids, was synthesized as a part of our research in the antitubercular field, according to an international program with the Tuberculosis Antimicrobial Acquisition and Coordinating Facility (TAACF). This work reports the preparation and analytical and spectroscopic characterization (MS, UV, IR, 1H NMR) of all compounds synthesized. Among these only

Paolo Sanna; Antonio Carta; Laura Gherardini; Mohammad Esmail Rahbar Nikookar

2002-01-01

288

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

SciTech Connect

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

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

2008-03-17

289

LATE REACTION, PERSISTENT REACTION AND DOUBTFUL ALLERGIC REACTION: THE PROBLEMS OF INTERPRETATION  

PubMed Central

The standard method of patch test reading is to read the test site for any positive allergy at 48 hr and then again at 72/96 hr. A late reading on the seventh day is also advised to exclude the irritant reaction (IR) and to notice some delayed development of allergic reaction. However, multiple visits are often difficult for the patient; therefore, this late reading is sometimes omitted. Here a case of plantar hyperkeratosis, due to allergic contact dermatitis, is reported with some insight into interpretation of the patch test. The patient showed delayed patch test reaction to formaldehyde and colophony, which has never been reported before. PMID:20049272

Sarma, Nilendu

2009-01-01

290

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.

291

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.

292

Synthesis and antitubercular activity of 3-aryl substituted-2-(1 H(2 H)benzotriazol-1(2)-yl)acrylonitriles # 1 # Part of this work was presented as a poster communication at the 2nd European Symposium on Antimicrobial Agents, Hradec Kralove, Czech Republic, 1–4 July 1998  

Microsoft Academic Search

A series of 22 3-aryl substituted-2-(1H(2H)-benzotriazol-1(2)-yl)acrylonitriles was synthesized for a preliminary in vitro evaluation of antitubercular activity according to an international program with the Tuberculosis Antimicrobial Acquisition & Coordinating Facility (TAACF). This work reports the synthetic approach and analytical and spectroscopic characterization (UV, IR, 1H- and 13C-NMR) of all compounds synthesized. Several compounds showed an interesting activity in the preliminary screening

Paolo Sanna; Antonio Carta; Mohammad E. Rahbar Nikookar

2000-01-01

293

The partial (1)H NMR spectra of Al-OH and molecular H(2)O in hydrous aluminosilicate glasses: Component-Resolved analysis of (27)Al-(1)H cross polarization and (1)H spin-echo MAS NMR spectra.  

PubMed

The Component-Resolved methodology was applied to (1)H spin-echo and (27)Al-(1)H cross polarization (CP) MAS NMR data of aluminosilicate glasses. The method was able to resolve two components with different T2 relaxation rates, hydroxyl groups (OH) and molecular water (H(2)O(mol)), from the spin-echo data and to determine partial spectra and the relative abundances of OH and H(2)O(mol). The algorithm resolved two to three components with different (27)Al-(1)H CP dynamics from the (27)Al-(1)H cross polarization data; the obtained partial NMR spectra for Al-OH are in excellent agreement with those obtained previously from the difference spectra between spectra with various contact times and confirm previous quantitative results and models for the Al-OH, Si-OH and H(2)O(mol) speciation (Malfait and Xue, 2010). PMID:20418075

Malfait, Wim J; Xue, Xianyu

2010-01-01

294

FT?IR Study of the Hydrolysis and Polymerization of Tetraethyl Orthosilicate and Polydimethyl Siloxane in the Presence of Tetrabutyl Orthotitanate  

Microsoft Academic Search

In this work, we have used FT?IR spectroscopy to study the hydrolysis and polymerization reactions of tetraethyl orthosilicate (TEOS) and polydimethyl?siloxane (PDMS) in the presence of tetrabutyl orthotitanate (TBOT). These reactions are used for obtaining SiO2–PDMS–TiO2 organically modified silicates (Ormosils). In order to obtain semi?quantitative information about such reactions, a deconvolution procedure of the FT?IR spectra has been done by

L. Téllez; J. Rubio; F. Rubio; E. Morales; J. L. Oteo

2004-01-01

295

FT-IR/PAS characteristic of the Ni-NiO/Al{2}O{3} catalyst  

NASA Astrophysics Data System (ADS)

Carbon deposits formed on the catalysts' surface is characterized by the different properties. This depends, among others, on the temperature of the catalytic reaction conducted. Application of FT-IR/PA (Fourier transform infrared photoacoustic) spectroscopy allows to examine the carbon deposit forms created during the reaction. Samples of the commercial KUB-3 catalyst (Ni-NiO/Al{2}O{3}) taken from the industrial bed after three-year continuous work (applied for the hydrogenation of benzene) were characterized by means of FT-IR/PAS.

Ryczkowski, J.; Pasieczna, S.; Sto?ecki, K.; Borowiecki, T.

2006-11-01

296

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

297

Carbon nanotube IR detectors (SV)  

SciTech Connect

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

Leonard, F. L.

2012-03-01

298

Mechanistic investigation and reaction kinetics of the low-pressure copolymerization of cyclohexene oxide and carbon dioxide catalyzed by a dizinc complex.  

PubMed

The reaction kinetics of the copolymerization of carbon dioxide and cyclohexene oxide to produce poly(cyclohexene carbonate), catalyzed by a dizinc acetate complex, is studied by in situ attenuated total reflectance infrared (ATR-IR) and proton nuclear magnetic resonance ((1)H NMR) spectroscopy. A parameter study, including reactant and catalyst concentration and carbon dioxide pressure, reveals zero reaction order in carbon dioxide concentration, for pressures between 1 and 40 bar and temperatures up to 80 °C, and a first-order dependence on catalyst concentration and concentration of cyclohexene oxide. The activation energies for the formation of poly(cyclohexene carbonate) and the cyclic side product cyclohexene carbonate are calculated, by determining the rate coefficients over a temperature range between 65 and 90 °C and using Arrhenius plots, to be 96.8 ± 1.6 kJ mol(-1) (23.1 kcal mol(-1)) and 137.5 ± 6.4 kJ mol(-1) (32.9 kcal mol(-1)), respectively. Gel permeation chromatography (GPC), (1)H NMR spectroscopy, and matrix-assisted laser desorption/ionization time-of-flight (MALDI-ToF) mass spectrometry are employed to study the poly(cyclohexene carbonate) produced, and reveal bimodal molecular weight distributions, with narrow polydispersity indices (?1.2). In all cases, two molecular weight distributions are observed, the higher value being approximately double the molecular weight of the lower value; this finding is seemingly independent of copolymerization conversion or reaction parameters. The copolymer characterization data and additional experiments in which chain transfer agents are added to copolymerization experiments indicate that rapid chain transfer reactions occur and allow an explanation for the observed bimodal molecular weight distributions. The spectroscopic and kinetic analyses enable a mechanism to be proposed for both the copolymerization reaction and possible side reactions; a dinuclear copolymerization active site is implicated. PMID:21973120

Jutz, Fabian; Buchard, Antoine; Kember, Michael R; Fredriksen, Siw Bodil; Williams, Charlotte K

2011-11-01

299

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

PubMed Central

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

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

2014-01-01

300

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

PubMed

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

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

2012-04-01

301

Looking for new antileishmanial derivatives in 8-nitroquinolin-2(1H)-one series.  

PubMed

From a recently identified antileishmanial pharmacophore, a structure-activity relationship study was conducted by introducing various aminated, phenoxy or thiophenoxy moieties at position 4 of the 8-nitroquinolin-2(1H)-one scaffold, using SNAr reactions. Thus a series of 47 derivatives was synthesized and evaluated in vitro on the promastigote stage of Leishmania donovani. In parallel, the cytotoxicity of the active molecules was tested on the human HepG2 cell line. The results we obtained showed that the introduction of a substituent at position 4 of the antileishmanial pharmacophore can either lead to inactive or active derivatives, depending on the nature of the substituent. Aminated moieties appear as very unfavorable toward antileishmanial activity, while phenoxy or thiophenoxy moieties were shown to maintain the in vitro antileishmanial profile, especially when the phenyl ring of these moieties was substituted at the para or ortho position by a halogen atom (except fluorine), a trifluoromethyl group or a methyl group. Most of these derivatives showed a lack of solubility in the culture media which hindered the in vitro determination of both their cytotoxicity and activity against the intracellular amastigoste stage of L. donovani. PMID:25559208

Kieffer, Charline; Cohen, Anita; Verhaeghe, Pierre; Hutter, Sébastien; Castera-Ducros, Caroline; Laget, Michèle; Remusat, Vincent; M'Rabet, Manel Kraiem; Rault, Sylvain; Rathelot, Pascal; Azas, Nadine; Vanelle, Patrice

2015-03-01

302

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

303

Coprates Chasma Landslides in IR  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

Today's daytime IR image is of a portion of Coprates Chasma, part of Valles Marineris. As with yesterday's image, this image shows multiple large landslides.

Image information: IR instrument. Latitude -8.2, Longitude 300.2 East (59.8 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.

2005-01-01

304

Xanthe Terra Landslide in IR  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

This is a daytime IR image of a chaos region within Xanthe Terra. As with earlier images, the landslide in this image is caused by the failure of steep slopes releasing material to form the landslide deposit.

Image information: IR instrument. Latitude 3.1, Longitude 309.7 East (50.3 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.

2005-01-01

305

Towards Hydrogen Evolution Initiated by LED Light: 2-(1H-1,2,3-Triazol-4-yl)pyridine-Containing Polymers as Photocatalyst.  

PubMed

Two- and three-component polymethacrylates, featuring a 2-(1-substituted-1H-1,2,3-triazol-4-yl)pyridine-based metal complex as photosensitizer, a viologen-type electron mediator, and a triethylene glycol methyl ether as solubilizing part are synthesized by statistical reversible addition-fragmentation chain transfer (RAFT) radical polymerization allowing the construction of well-defined copolymers. Thereby, heteroleptic ruthenium(II) and iridium(III) complexes serve as charged photosensitizers. In hydrogen evolution experiments, as proof-of-concept, triethylamine is utilized as a sacrificial donor and colloidal platinum as hydrogen evolving catalyst. The macromolecules bearing heteroleptic iridium(III) complexes of the general formula [Ir(ppy)2 (trzpy)]PF6 (ppy: 2-phenylpyridine; trzpy: 2-(1-substituted-1H-1,2,3-triazol-4-yl)pyridine) and [Ir(btac)2 (trzpy)]PF6 (btac: 3-(2-benzothiazolyl)-7-(diethylamino)coumarin) are photocatalytically active producing molecular hydrogen in water upon illumination at 470 nm. By changing the cyclometalating ligand from ppy to btac, the photocatalytic performance of the copolymer as reflected in the turnover number increases by two orders of magnitude. PMID:25656046

Happ, Bobby; Kübel, Joachim; Pfeffer, Michael G; Winter, Andreas; Hager, Martin D; Dietzek, Benjamin; Rau, Sven; Schubert, Ulrich S

2015-04-01

306

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

307

IR Thermography NDE of ISS Radiator Panels  

NASA Technical Reports Server (NTRS)

The presentation covers an active and a passive infrared (IR) thermography for detection of delaminations in the radiator panels used for the International Space Station (ISS) program. The passive radiator IR data was taken by a NASA astronaut in an extravehicular activity (EVA) using a modified FLIR EVA hand-held camera. The IR data could be successfully analyzed to detect gross facesheet disbonds. The technique used the internal hot fluid tube as the heat source in analyzing the IR data. Some non-flight ISS radiators were inspected using an active technique of IR flash thermography to detect disbond of face sheet with honeycomb core, and debonds in facesheet overlap areas. The surface temperature and radiated heat emission from flight radiators is stable during acquisition of the IR video data. This data was analyzed to detect locations of unexpected surface temperature gradients. The flash thermography data was analyzed using derivative analysis and contrast evolutions. Results of the inspection are provided.

Koshti, Ajay; Winfree, William; Morton, Richard; Wilson, Walter; Reynolds, Gary

2010-01-01

308

Synthesis, conformational, spectroscopic and chemical reactivity analysis of 2-cyano-3-(1H-pyrrol-2-yl)acrylohydrazide using experimental and quantum chemical approaches  

NASA Astrophysics Data System (ADS)

This paper describes the synthesis, spectroscopic (1H and 13C NMR, UV-Visible, FT-IR and ESI Mass), conformational analysis, chemical reactivity and non-linear optical (NLO) properties of newly synthesized pyrrole derivative 2-cyano-3-(1H-pyrrol-2-yl)acrylohydrazide (2CPA) C8H8N4O using experimental and quantum chemical techniques. The presence of signal at ? 8.010 ppm due to vinyl proton as well as NH and NH2 protons signals at 11.054 and 2.499 ppm in experimental 1H NMR spectrum indicate that 2CPA contain sbnd CHdbnd CCNsbnd and sbnd NHsbnd NH2 frame. The combined experimental and theoretical symmetric (3194 cm-1) and asymmetric (3221 cm-1) stretching wavenumber analysis confirms free NH2 group in the solid phase FT-IR spectrum of the synthesized compound. The interaction energies of dimer formation using density functional theory (DFT) and Quantum theory of Atoms in Molecules (QTAIM) calculations are found to be 20.210, 19.683 kcal/mol, respectively. The maximum values of the electrophilic reactivity descriptors at C6 indicate that this site is more prone to nucleophilic attack and favoring the formation of heterocyclic derivatives. A natural bond orbital (NBOs) analysis has been carried out to investigate intramolecular charge transfer, conjugative and hyperconjugative interactions within molecule. The calculated first hyperpolarizability (?0) of 2CPA, indicates that investigated molecule will show non-linear optical response and might be used as non-linear optical (NLO) material.

Rawat, Poonam; Singh, R. N.

2015-02-01

309

Use of 1H/23Na and 1H/31P double frequency tuned birdcage coils to study in vivo carbon tetrachloride-induced hepatotoxicity in rats.  

PubMed

In vivo 1H and 23Na magnetic resonance imaging (MRI) and 31P magnetic resonance spectroscopy (MRS) techniques were used to study CCl4-induced acute hepatotoxicity in rats in situ. One or two hours following exposure to CCl4, a localized edematous region was detected in the liver by 1H MRI. The CCl4-induced edema was localized in a region surrounding the hepatic portal vein. With the use of a 23Na/1H double frequency tuned bird-cage imaging coil an increase in Na+ ion flux was also observed in the same region as the edematous region detected by 1H-MRI. Pretreatment with alpha-phenyl-tert-butyl nitrone (PBN), a free radical spin trap, 30 min prior to CCl4 exposure, was found to reduce the CCl4-induced edematous response in the liver observed in either 1H or 23Na-NMR images. Inhibition of the CCl4-induced edematous response in rat liver by PBN demonstrates that free radical intermediates, arising from the metabolism of CCl4, are possibly the key causal agents in the initiation of the edematous response. In addition, with the use of a 31P/1H double frequency tuned bird-cage imaging/spectroscopy coil, localized 31P spectra (ISIS) were obtained from the regions of CCl4-induced "tissue damage" observed in the 1H-MRI images. The most notable changes observed from the 31P spectra were an increase in inorganic phosphate (Pi) and a decrease in hepatocytosolic pH in the CCl4-treated rat livers in comparison to saline-treated control livers. PMID:1501538

Towner, R A; Janzen, E G; Chu, S C; Rath, A

1992-01-01

310

Structural and in vitro cytotoxicity studies on 1H-benzimidazol-2-ylmethyl-N-phenyl amine and its Pd(II) and Pt(II) complexes  

NASA Astrophysics Data System (ADS)

[MLCl 2]· zH 2O (L = (1H-benzimidazol-2-ylmethyl)-N-phenyl amine; M = Pd, z = 0; M = Pt, z = 1) and [PdL(OH 2) 2]·2X·zH 2O (X = Br, I, NO 3, z = 0; X = SCN, z = 1) complexes were synthesized as potential anticancer compounds and characterized by elemental analysis, spectral and thermal methods. FT-IR and 1H NMR studies revealed that the benzimidazole L is coordinated to the metal ions via the pyridine-type nitrogen (N py) of the benzimidazole ring and secondary amino group (NH sec). Quantum mechanical calculations of energies, geometries, vibrational wavenumbers, and 1H NMR of the benzimidazole L and its complexes were carried out by density functional theory using B3LYP functional combined with 6-31G(d) and LANL2DZ basis sets. Natural bond orbitals (NBOs) and frontier molecular orbitals were performed at B3LYP/LANL2DZ level of theory. The synthesized ligand, in comparison to its metal complexes was screened for its antibacterial activity. The benzimidazole L is more toxic against the bacterium Staphylococcus aureus (MIC = 58 ?g/mL) than the standard tetracycline (MIC = 82 ?g/mL). The complexes showed cytotoxicity against breast cancer, Colon Carcinoma, and human heptacellular Carcinoma cells. The platinum complex ( 6) displays cytotoxicity (IC 50 = 12.4 ?M) against breast cancer compared with that reported for cis-platin 9.91 ?M.

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

2011-10-01

311

Comparative field evaluation of repellent formulations containing deet and IR3535 against mosquitoes in Queensland, Australia.  

PubMed

Field trials comparing repellent formulations containing IR3535 (ethyl butylacetylaminopropionate) and deet (N,N-diethyl-3-methylbenzamide) against mosquitoes in Queensland, Australia, were conducted. Two repellents were compared: Avon Bug Guard, containing 7.5% IR3535; and Australian Defense Force (ADF) deet, containing 35% deet in a gel. Two tests were conducted, one in February-March 2006, and the second in February 2007. In the 1st test, the predominant mosquito species collected were Mansonia uniformis (58.9% of collection) and Culex annulirostris (33.4%), and in the 2nd test, the predominant species was Aedes vigilax (85.7% of collection). In the 1st test, Avon Bug Guard provided >95% protection against all mosquitoes for only 1 h, and ADF deet provided the same level of protection for 5 h. In the 2nd field test, Avon Bug Guard provided only 85% protection against all mosquitoes 1 h after repellent application, while ADF deet provided 5 h of protection. The study showed that ADF deet provided significantly better protection against mosquitoes than Avon Bug Guard (IR3535). PMID:20099600

Frances, S P; MacKenzie, D O; Rowcliffe, K L; Corcoran, S K

2009-12-01

312

Allergic reactions  

MedlinePLUS

... more often in people who have a family history of allergies . Substances that don't bother most people ( ... reaction is getting worse. The person has a history of severe allergic reactions (check for a medical ID ...

313

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

314

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

315

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.

Minerva Deland School

2011-10-03

316

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

William C. Robertson, Ph.D.

2010-03-01

317

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

318

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

319

A critical evaluation of heteronuclear TOCSY (HEHAHA) experiments for 1H,6Li 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. PMID:25169197

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

2014-12-01

320

"Batch" kinetics in flow: online IR analysis and continuous control.  

PubMed

Currently, kinetic data is either collected under steady-state conditions in flow or by generating time-series data in batch. Batch experiments are generally considered to be more suitable for the generation of kinetic data because of the ability to collect data from many time points in a single experiment. Now, a method that rapidly generates time-series reaction data from flow reactors by continuously manipulating the flow rate and reaction temperature has been developed. This approach makes use of inline IR analysis and an automated microreactor system, which allowed for rapid and tight control of the operating conditions. The conversion/residence time profiles at several temperatures were used to fit parameters to a kinetic model. This method requires significantly less time and a smaller amount of starting material compared to one-at-a-time flow experiments, and thus allows for the rapid generation of kinetic data. PMID:24288212

Moore, Jason S; Jensen, Klavs F

2014-01-01

321

Hydrogen Isotope Exchange Reactions in an Electrical Discharge  

Microsoft Academic Search

Hydrogen isotope exchange reactions occurring in (H2O, D2)or (D2O, H2) reacting system under a DC electricaldischarge were investigated using spectroscopic methods such asFourier-transform infrared (FTIR) and plasma emission spectroscopy(PES). The progress of the reactions was determined by real-time measurementof the IR absorbance of HDO molecule, a major product of the reaction. Theprogress of the reaction was studied as a function

H. J. Kim; Y. D. Park; W. M. Lee

2000-01-01

322

COMPUTING AERIAL SUPPRESSION EFFECTIVENES BY IR MONITORING  

Microsoft Academic Search

This document describes the methodology developed to analyse the IR images obtained during the aerial suppression experiments that were conducted in Ngarkat Conservation Park, South Australia, on 3 rd - 5 th March 2008. This methodology has been specifically developed in order to be able to extract the maximum information from the IR images taken from an observing helicopter, in

Eulalia Planas; Elsa Pastor; Yolanda Pérez; Matt Plucinski; Jim Gould

323

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

324

IR Investigations of the Structure of PVC  

Microsoft Academic Search

An infrared method has been developed to characterize the double bond and crystallizable syndiotactic sequence content of PVC. Good agreement was found for the double bond content as determined by the IR method and chemical methods. The IR crystallizable content was slightly greater than the x-ray crystallinity, presumably because not all crystallizable sequences actually crystallized.

P. Simak

1982-01-01

325

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

2005-09-08

326

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

327

Reaction mechanisms of Li(0.30)La(0.57)TiO3 powder with ambient air: H+/Li+ exchange with water and Li2CO3 formation.  

PubMed

The proton/lithium exchange property of the lithium lanthanum titanate Li(0.30)La(0.57)TiO(3) (named LLTO) is shown to occur at room temperature under ambient air. The (1)H and (7)Li MAS NMR, TGA analysis and IR spectroscopy techniques are used to probe reaction mechanisms. XRPD analysis gives evidence of the topotactic character of this exchange reaction. As for exchange in aqueous solution, it is shown that Li(0.30)La(0.57)TiO(3) is able to dissociate water on the grain surface and then to exchange H(+) for Li(+) into the perovskite structure. Lithium hydroxide is then formed on the grain surface and afterwards reacts with CO(2) contained in air to form Li(2)CO(3). It is shown that this mechanism is reversible. When the aged sample (aging in air for 5 months at room temperature) is annealed at 400 degrees C for two hours, the initial LLTO sample is totally recovered, a mass loss is observed and the carbonate signal in IR spectra disappears, demonstrating the reversibility of the carbonation reaction process. PMID:20372722

Boulant, Anthony; Bardeau, Jean Francois; Jouanneaux, Alain; Emery, Joël; Buzare, Jean-Yves; Bohnke, Odile

2010-04-28

328

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

329

Northern Polar Spring in IR  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

Released 12 March 2004

The Odyssey spacecraft has completed a full Mars year of observations of the red planet. For the next several weeks the Image of the Day will look back over this first mars year. It will focus on four themes: 1) the poles - with the seasonal changes seen in the retreat and expansion of the caps; 2) craters - with a variety of morphologies relating to impact materials and later alteration, both infilling and exhumation; 3) channels - the clues to liquid surface flow; and 4) volcanic flow features. While some images have helped answer questions about the history of Mars, many have raised new questions that are still being investigated as Odyssey continues collecting data as it orbits Mars.

Infrared images taken during the daytime exhibit both the morphological and thermophysical properties of the surface of Mars. Morphologic details are visible due to the effect of sun-facing slopes receiving more energy than antisun-facing slopes. This creates a warm (bright) slope and cool (dark) slope appearance that mimics the light and shadows of a visible wavelength image. Thermophysical properties are seen in that dust heats up more quickly than rocks. Thus dusty areas are bright and rocky areas are dark.

This image was collected October 19, 2002 during the northern spring season. The top half of this daytime IR image shows the North Polar sand sea.

Image information: IR instrument. Latitude 76.2, Longitude 226.8 East (133.2 West). 19 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

330

Electronic [UV-Visible] and vibrational [FT-IR, FT-Raman] investigation and NMR-mass spectroscopic analysis of terephthalic acid using quantum Gaussian calculations.  

PubMed

In this research work, the vibrational IR, polarization Raman, NMR and mass spectra of terephthalic acid (TA) were recorded. The observed fundamental peaks (IR, Raman) were assigned according to their distinctiveness region. The hybrid computational calculations were carried out for calculating geometrical and vibrational parameters by DFT (B3LYP and B3PW91) methods with 6-31++G(d,p) and 6-311++G(d,p) basis sets and the corresponding results were tabulated. The molecular mass spectral data related to base molecule and substitutional group of the compound was analyzed. The modification of the chemical property by the reaction mechanism of the injection of dicarboxylic group in the base molecule was investigated. The (13)C and (1)H NMR spectra were simulated by using the gauge independent atomic orbital (GIAO) method and the absolute chemical shifts related to TMS were compared with experimental spectra. The study on the electronic and optical properties; absorption wavelengths, excitation energy, dipole moment and frontier molecular orbital energies, were performed by hybrid Gaussian calculation methods. The orbital energies of different levels of HOMO and LUMO were calculated and the molecular orbital lobe overlapping showed the inter charge transformation between the base molecule and ligand group. From the frontier molecular orbitals (FMO), the possibility of electrophilic and nucleophilic hit also analyzed. The NLO activity of the title compound related to Polarizability and hyperpolarizability were also discussed. The present molecule was fragmented with respect to atomic mass and the mass variation depends on the substitutions have also been studied. PMID:25561302

Karthikeyan, N; Joseph Prince, J; Ramalingam, S; Periandy, S

2015-03-15

331

Synthesis, Structure and Spectroscopic Properties of the Dimer ?-Bis[2(1H)-Tetrahydropyrimidinone] Octakis[2(1H)-Tetrahydropyrimidinone] Dicopper(II) Perchlorate  

Microsoft Academic Search

The complex ?-Bis[2(1H)-tetrahydropyrimidinone]octakis[2(1H)-tetrahydropyrimidinone]dicopper(II) perchlorate has been synthesized and its crystal structure has been determined by X-ray diffraction at room temperature. Crystals are triclinic (space group p); a=11.709(8), b = 12.750(12), c=12.891(11)Å, ? = 62.98(7), ?=67.90(6), ? = 71.75(7)[ddot], R = 0.0675 and Rw = 0.0743. The unit cell contains one centro-symmetric, dimeric cation, [Cu2(PU)10], and four non-coordinated CIO- anions. The

I. Ková?ik; J. Kožíšek; J. Hanušík; H. Langfelderová; V. K. Voronkova; L. V. Mosina; Yu. V. Yablokov

1992-01-01

332

Which Oxidation State Leads to O-O Bond Formation in Cp*Ir(bpy)Cl-Catalyzed Water Oxidation, Ir(V), Ir(VI), or Ir(VII)?  

E-print Network

Which Oxidation State Leads to O-O Bond Formation in Cp*Ir(bpy)Cl-Catalyzed Water Oxidation, Ir(V), Ir(VI), or Ir(VII)? Rong-Zhen Liao* and Per E. M. Siegbahn* Department of Organic Chemistry by the Cp*Ir(bpy)Cl (Cp* = pentamethylcyclopentadienyl, bpy = 2,2-bipyridine) complex. One

Liao, Rongzhen

333

Investigation of the hydrolysis of (3-triethoxysilylpropyl)succinic acid anhydride by means of FT-IR  

Microsoft Academic Search

The kinetic data (rate constant, Arrhenius activation energy, frequency factor) of the hydrolysis reaction of the anhydride\\u000a moiety of (3-triethoxysilylpropyl)succinic acid anhydride (TESP-SA) were investigated by means of FT-IR monitoring the decrease\\u000a of the carbonyl stretching band at 1778 cm?1. The reaction had been conducted in an excess of water under acidic conditions (pseudo-first order reaction). In addition,\\u000a the application of

Christian Schramm; Beate Rinderer

2008-01-01

334

IR line scanner on UAV  

NASA Astrophysics Data System (ADS)

This paper introduces the designing principle and method of the IR line scanner on UAV in three aspects of optical-mechanical system, electronics system and processing software. It makes the system achieve good results in practical application that there are many features in the system such as light weight, small size, low power assumption, wide field of view, high instantaneous field of view, high noise equivalent temperature difference, wirelessly controlled and so on. The entire system is designed as follows: Multi-element scanner is put into use for reducing the electrical noise bandwidth, and then improving SNR; Square split aperture scanner is put into use for solving the image ratation distortion, besides fit for large velocity to height ratio; DSP is put into use for non-uniformity correction and background nosie subtraction, and then improving the imagery quality; SD card is put into use as image data storage media instead of the hard disk; The image data is stored in SD card in FAT32 file system, easily playbacked by processing software on Windows and Linux operating system; wireless transceiver module is put into use for wirelessly controlled.

Liu, Shi-chao; Qin, Jie-xin; Qi, Hong-xing; Xiao, Gong-hai

2011-08-01

335

Time-resolved near IR and 2D-correlation spectroscopic studies of the polymerization process of 3-aminopropyltriethoxysilane  

NASA Astrophysics Data System (ADS)

The polymerization behavior of 3-aminopropyltriethoxysilane, a process initiated by water molecules, has been examined using time-resolved Near IR and 2D Near IR correlation spectra. In the time-resolved Near IR spectra, the bands at 5184 and 5300 cm-1 have been assigned to water molecules and the silanol (SiOH) group, respectively. The intensities of the two Near IR bands decrease markedly as the reaction proceeds, indicating that water molecules and the SiOH groups are utilized in hydrolysis of the ethoxy groups and formation of a siloxane bond, respectively. It has also been found that this polymerization process is distinctly reflected in the 2D Near IR correlation spectra.

Ogasawara, Toshiaki; Nara, Akishi; Okabayashi, Hirofumi; Nishio, Etsuo; O'Connor, Charmian J.

2000-03-01

336

An Anion-Dependent Switch in Selectivity Results from a Change of C-H Activation Mechanism in the Reaction of an  

E-print Network

in the Reaction of an Imidazolium Salt with IrH5(PPh3)2 Leah N. Appelhans, Daniele Zuccaccia, Anes Kovacevic imidazolium salts causes the kinetic reaction products with IrH5(PPh3)2 to switch from chelating N observable counterion-dependent switching of reaction pathway in solution. Even then, the two transition

Baltisberger, Jay H.

337

Crystal structure and luminescent properties of [1-(biphenyl-4-yl)-1H-imidazole-?N 3]di­chloridozinc  

PubMed Central

The mononuclear title compound, [ZnCl2(C15H12N2)2], was synthesized by reaction of zinc chloride and 1-(biphenyl-4-yl)-1H-imidazole (bpi) under hydro­thermal conditions. The ZnII atom is tetra­hedrally coordinated by the free imidazole N atoms of two bpi ligands and by two Cl atoms. The bpi ligands are not planar, with dihedral angles of 37.52?(14) and 42.45?(14)° between the phenyl rings and 37.13?(14) and 40.05?(14)° between the phenyl rings and the attached imidazole rings, respectively. Mutual ?–? inter­actions, with a centroid-to-centroid distance of 3.751?(2)?Å between the phenyl and imidazole rings of neighbouring ligands, are present, leading to dimers that are arranged in rows parallel to [-211].

Liu, Xiao-Xiao; Wang, Yuan

2015-01-01

338

Lanthanide derivatives comprising arylhydrazones of ?-diketones: cooperative E/Z isomerization and catalytic activity in nitroaldol reaction.  

PubMed

Two complexes [KLa(HL(1))2{(CH3)2NCHO}2(H2O)3] () and [Sm(H2O)9](E-H2L(2))3·2H2O () were synthesized by the reaction of lanthanum(iii) and samarium(iii) nitrates with potassium 3-(2-(2,4-dioxopentan-3-ylidene)hydrazinyl)-2-hydroxy-5-nitrobenzenesulfonate (KH2L(1)) and potassium (E,Z)-5-chloro-3-(2-(1,3-dioxo-1-phenylbutan-2-ylidene)hydrazinyl)-2-hydroxybenzenesulfonate (KH2L(2)), respectively. Both complexes were fully characterized by elemental analysis, IR, (1)H and (13)C NMR spectroscopy, ESI-MS and single-crystal X-ray diffraction. Cooperative E,Z?E isomerization of KH2L(2), induced by resonance assisted hydrogen bonding and ionic interactions, occurs upon the interaction with Sm(iii). Catalytic activities of KH2L(1,2) and their lanthanide derivatives were evaluated in the Henry reaction of nitroethane with a variety of aromatic and aliphatic aldehydes. Good yields (up to 91%) and diastereoselectivities (syn/anti 3?:?1) were observed in the reactions catalyzed by in water. PMID:25698467

Mahmudov, Kamran T; Guedes da Silva, M Fátima C; Sutradhar, Manas; Kopylovich, Maximilian N; Huseynov, Fatali E; Shamilov, Nazim T; Voronina, Anna A; Buslaeva, Tatyana M; Pombeiro, Armando J L

2015-03-10

339

Combustion diagnostics at a biomass-fired grate furnace using FT-IR absorption spectroscopy for hot gas measurements  

Microsoft Academic Search

In-situ Fourier transform infrared (FT-IR) absorption spectroscopy has been applied as a combustion diagnostic tool to a biomass-fired travelling grate furnace with the purpose of obtaining information about the volatilisation of gaseous compounds from the fuel bed as well as the further reactions of these compounds during the combustion process. For these aims FT-IR in-situ measurements are carried out directly

Thomas Fleckl; Helmut Jäger; Ingwald Obernberger

340

Predicted NO/sub 2/ ir chemiluminescence in the natural atmosphere. Technical report, February-May 1986  

SciTech Connect

Results from the author's recent theoretical study of NO/sub 2/ ir chemiluminescence from the NO + 0 and NO + O/sub 3/ reactions are employed in a new upper atmospheric NO/sub 2/ ir radiance model. Predictions are made for altitude-dependent and column-integrated NO/sub 2/ chemiluminescent radiance in four vibrational bands, and comparison is made with previous model predictions.

Adler-Golden, S.

1986-05-13

341

Molecular characterization, tissue expression profile and SNP analysis of the porcine NR1H4 gene.  

PubMed

Nuclear Receptor subfamily 1, group H, member 4 (NR1H4) is a receptor for bile acids and has an important role in regulating energy metabolism in liver, muscle and adipose tissues in humans and animals. In this study, we cloned the full coding region of NR1H4 gene from porcine Longissimus dorsi by Rapid amplification of cDNA end (RACE). Results indicated that the open reading frame of NR1H4 covered 1461 bp encoding 486 amino acid residues and the deduced amino acid sequence was 91-94 % identical to that of Homo sapiens, Bos taurus, Macaca mulatta, Gorilla gorilla, and Ovis aries. Bioinformatic analysis indicated that NR1H4 contained 31 phosphorylation sites with 14 serine, 6 threonine and 11 tyrosine. One single nucleotide polymorphism (SNP) was detected by PCR-RFLP in 3' untranslated region of exon 9 (NR1H4) and the allele frequency analysis showed that A allele frequency was low among 396 pigs from five breeds. The NR1H4 mRNA expression pattern showed that NR1H4 gene was expressed highly in live and Longissimus dorsi. This work provided an important experimental basis for further research on mechanism of lipid metabolism and fat deposition in pigs. PMID:25034892

Yang, Hu; Jiang, Jun; Xu, Xingli; He, Jun; He, Changqing; Ma, Haiming

2014-10-01

342

The effect of treatment with Campath-1H in patients with autoimmune cytopenias.  

PubMed

We describe 21 patients with severe and life-threatening autoimmune cytopenias resistant to standard immunosuppression who were treated with the monoclonal antibody Campath-1H. Four patients had autoimmune neutropenia, four had autoimmune haemolytic anaemia, four had pure red cell aplasia, one had immune thrombocytopenia purpura (ITP), three had autoimmune haemolytic anaemia and ITP (Evan's syndrome), three had autoimmune pancytopenia (ITP, autoimmune neutropenia and autoimmune haemolytic anaemia), one had ITP (associated with acquired Glanzmann's disease) and autoimmune neutropenia, and one had ITP and red cell aplasia. Campath-1H was administered at a dose of 10 mg/d as an intravenous infusion for 10 d. Responses were seen in 15 patients, which were sustained in six. Relapse occurred in eight patients after Campath-1H treatment. Patients entering the study later, received cyclosporine after Campath-1H in an attempt to reduce the incidence of relapse. Three patients received a second course of Campath-1H; all responded but later relapsed. Fourteen patients are alive at a median of 12 months (range 4-61) after Campath-1H. Campath-1H represents an alternative therapeutic option for severe, refractory autoimmune cytopenias. PMID:11564082

Willis, F; Marsh, J C; Bevan, D H; Killick, S B; Lucas, G; Griffiths, R; Ouwehand, W; Hale, G; Waldmann, H; Gordon-Smith, E C

2001-09-01

343

Clusters [Ma(GaCp*)b(CNR)c] (M = Ni, Pd, Pt): synthesis, structure, and Ga/Zn exchange reactions.  

PubMed

Reactions of homoleptic isonitrile ligated complexes or clusters of d(10)-metals with the potent carbenoid donor ligand GaCp* are presented (Cp* = pentamethylcyclopentadienyl). Treatment of [Ni4(CNt-Bu)7], [{M(CNR)2}3] (M = Pd, Pt) and [Pd(CNR)2Me2] (R = t-Bu, Ph) with suitable amounts of GaCp* lead to the formation of the heteroleptic, tri- and tetranuclear clusters [Ni4(CNt-Bu)7(GaCp*)3] (1), [{M(CNt-Bu)}3(GaCp*)4] (M = Pd: 2a, Pt: 2b), and [{Pd(CNR)}4(GaCp*)4] (R = t-Bu: 3a, Ph: 3b). The reactions involve isonitrile substitution reactions, GaCp* addition reactions, and cluster formation reactions. The new compounds were investigated for their ability to undergo Ga/Zn exchange reactions when treated with ZnMe2. The novel tetranuclear Zn-rich clusters [Ni4GaZn7(Cp*)2Me7(CNt-Bu)6] (4) and [{Pd(CNR)}4(ZnCp*)4(ZnMe)4] (R = t-Bu: 5a, Ph: 5b) were obtained and isolated. The electronic situation and geometrical arrangement of atoms of all compounds will be presented and discussed. All new compounds are characterized by solution (1)H, (13)C NMR and IR spectroscopy, elemental analysis (EA), liquid injection field desorption ionization mass spectrometry (LIFDI-MS) as well as single crystal X-ray crystallography. PMID:24283457

Molon, Mariusz; Dilchert, Katharina; Gemel, Christian; Seidel, Rüdiger W; Schaumann, Julian; Fischer, Roland A

2013-12-16

344

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

345

Irs2 and Irs4 synergize in non-LepRb neurons to control energy balance and glucose homeostasis.  

PubMed

Insulin receptor substrates (Irs1, 2, 3 and Irs4) mediate the actions of insulin/IGF1 signaling. They have similar structure, but distinctly regulate development, growth, and metabolic homeostasis. Irs2 contributes to central metabolic sensing, partially by acting in leptin receptor (LepRb)-expressing neurons. Although Irs4 is largely restricted to the hypothalamus, its contribution to metabolic regulation is unclear because Irs4-null mice barely distinguishable from controls. We postulated that Irs2 and Irs4 synergize and complement each other in the brain. To examine this possibility, we investigated the metabolism of whole body Irs4(-/y) mice that lacked Irs2 in the CNS (bIrs2(-/-)·Irs4(-/y)) or only in LepRb-neurons (Lepr (?Irs2) ·Irs4 (-/y) ). bIrs2(-/-)·Irs4(-/y) mice developed severe obesity and decreased energy expenditure, along with hyperglycemia and insulin resistance. Unexpectedly, the body weight and fed blood glucose levels of Lepr (?Irs2) ·Irs4 (-/y) mice were not different from Lepr (?Irs2) mice, suggesting that the functions of Irs2 and Irs4 converge upon neurons that are distinct from those expressing LepRb. PMID:24567904

Sadagurski, Marianna; Dong, X Charlie; Myers, Martin G; White, Morris F

2014-02-01

346

Quantifying Flaw Characteristics from IR NDE Data  

SciTech Connect

Work is presented which allows flaw characteristics to be quantified from the transient IR NDE signature. The goal of this effort was to accurately determine the type, size and depth of flaws revealed with IR NDE, using sonic IR as the example IR NDE technique. Typically an IR NDE experiment will result in a positive qualitative indication of a flaw such as a cold or hot spot in the image, but will not provide quantitative data thereby leaving the practitioner to make educated guesses as to the source of the signal. The technique presented here relies on comparing the transient IR signature to exact heat transfer analytical results for prototypical flaws, using the flaw characteristics as unknown fitting parameters. A nonlinear least squares algorithm is used to evaluate the fitting parameters, which then provide a direct measure of the flaw characteristics that can be mapped to the imaged surface for visual reference. The method uses temperature data for the heat transfer analysis, so radiometric calibration of the IR signal is required. The method provides quantitative data with a single thermal event (e.g. acoustic pulse or flash), as compared to phase-lock techniques that require many events. The work has been tested with numerical data but remains to be validated by experimental data, and that effort is underway.

Miller, W; Philips, N R; Burke, M W; Robbins, C L

2003-02-14

347

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

348

Gallium nitride micromechanical resonators for IR detection  

NASA Astrophysics Data System (ADS)

This paper reports on a novel technology for low-noise un-cooled detection of infrared (IR) radiation using a combination of piezoelectric, pyroelectric, electrostrictive, and resonant effects. The architecture consists of a parallel array of high-Q gallium nitride (GaN) micro-mechanical resonators coated with an IR absorbing nanocomposite. The nanocomposite absorber converts the IR energy into heat with high efficiency. The generated heat causes a shift in frequency characteristics of the GaN resonators because of pyroelectric effect. IR detection is achieved by sensing the shift in the resonance frequency and amplitude of the exposed GaN resonator as compared to a reference resonator that is included in the array. This architecture offers improved signal to noise ratio compared with conventional pyroelectric detectors as the resonant effect reduces the background noise and improves sensitivity, enabling IR detection with NEDTs below 5 mK at room temperature. GaN is chosen as the resonant material as it possesses high pyroelectric, electrostrictive, and piezoelectric coefficients and can be grown on silicon substrates for low-cost batch fabrication. Measured results of a GaN IR detector prototype and a thin-film nanocomposite IR absorber are presented in this paper.

Rais-Zadeh, Mina

2012-06-01

349

Hydrogen bonding. Part 17. IR and NMR study of the lower hydrates of choline chloride  

NASA Astrophysics Data System (ADS)

Choline chloride forms two lower hydrates — a dihydrate and a monohydrate — with quite unusual properties. The dihydrate is a highly structured liquid salt; the IR spectrum is similar to that of a crystalline framework clathrate hydrate, and there are separate 1H-NMR signals for the cation hydroxyl and water protons. The dihydrate is a crystalline solid at reduced pressure. The crystalline monohydrate only exists at reduced pressure; at atmospheric pressure it disproportionates to liquid dihydrate and anhydrous choline chloride. The anhydrous choline chloride thus formed is a previously unreported crystal modification of choline chloride.

Harmon, Kenneth M.; Avci, Günsel F.

1984-09-01

350

Intermolecular Interactions between Eosin Y and Caffeine Using 1H-NMR Spectroscopy  

PubMed Central

DETECHIP has been used in testing analytes including caffeine, cocaine, and tetrahydrocannabinol (THC) from marijuana, as well as date rape and club drugs such as flunitrazepam, gamma-hydroxybutyric acid (GHB), and methamphetamine. This study investigates the intermolecular interaction between DETECHIP sensor eosin Y (DC1) and the analyte (caffeine) that is responsible for the fluorescence and color changes observed in the actual array. Using 1H-NMR, 1H-COSY, and 1H-DOSY NMR methods, a proton exchange from C-8 of caffeine to eosin Y is proposed. PMID:25018772

Okuom, Macduff O.; Wilson, Mark V.; Jackson, Abby; Holmes, Andrea E.

2014-01-01

351

Intermolecular Interactions between Eosin Y and Caffeine Using (1)H-NMR Spectroscopy.  

PubMed

DETECHIP has been used in testing analytes including caffeine, cocaine, and tetrahydrocannabinol (THC) from marijuana, as well as date rape and club drugs such as flunitrazepam, gamma-hydroxybutyric acid (GHB), and methamphetamine. This study investigates the intermolecular interaction between DETECHIP sensor eosin Y (DC1) and the analyte (caffeine) that is responsible for the fluorescence and color changes observed in the actual array. Using (1)H-NMR, (1)H-COSY, and (1)H-DOSY NMR methods, a proton exchange from C-8 of caffeine to eosin Y is proposed. PMID:25018772

Okuom, Macduff O; Wilson, Mark V; Jackson, Abby; Holmes, Andrea E

2013-12-31

352

2-IR 1-Visible Sum Frequency Generation Study on Co-adsorption of CO and Ethylene  

NASA Astrophysics Data System (ADS)

Surface Vibrational Sum Frequency Generation (SFG) is applied to investigate the co-adsorption of CO and ethylene on Pt(111) from ultra high vacuum (UHV) to 1 atmosphere. The co-adsorption of CO and ethylene is a special system for study because CO is a poison for catalytic hydrogenation of ethylene as well as many other olefins. We report the first use of 2-IR 1-Visible SFG to monitor both CO and ethylene simultaneously during the co-adsorption process as well as under reaction conditions. In UHV, co-adsorption was observed when a clean Pt(111) surface was exposed to 5L of both CO and ethylene near room temperature. Pressure dependence up to 1 atmosphere and temperature dependence from 25C to 550C were investigated. For reaction studies, 2-IR 1-Visible SFG was used in conjunction with a packed column gas chromatograph to correlate surface species with reaction kinetics.

Kung, K.; Chen, P.; Wei, F.; Shen, Y.; Somorjai, G.

2000-03-01

353

Holographic RG flows with nematic IR phases  

E-print Network

We construct zero-temperature geometries that interpolate between a Lifshitz fixed point in the UV and an IR phase that breaks spatial rotations but preserves translations. We work with a simple holographic model describing two massive gauge fields coupled to gravity and a neutral scalar. Our construction can be used to describe RG flows in non-relativistic, strongly coupled quantum systems with nematic order in the IR. In particular, when the dynamical critical exponent of the UV fixed point is z=2 and the IR scaling exponents are chosen appropriately, our model realizes holographically the scaling properties of the bosonic modes of the quadratic band crossing model.

Sera Cremonini; Xi Dong; Junchen Rong; Kai Sun

2015-01-22

354

Microwave-Promoted Synthesis of 3,4-Dihydropyrimidin-2(1H)-(thio)ones Using IL-ONO as Recyclable Base Catalyst Under Solvent-Free Conditions  

Microsoft Academic Search

A mild, efficient, and solvent-free microwave (MW)–promoted Biginelli reaction for the synthesis of 3,4-dihydropyrimidin-2(1H)-(thio)ones in nitrite ionic liquid (IL-ONO) is described. This ionic liquid is a weak Lewis base catalyst, which can be easily recovered and reused in several runs. The satisfactory results were obtained with good yields and short reaction time, using a simple experimental procedure.

Mortaza Mirzai; Hassan Valizadeh

2012-01-01

355

MW-Promoted Synthesis of 3,4-dihydropyrimidin-2(1 h)-(Thio)ones Using IL-ONO as Recyclable Base Catalyst Under Solvent-Free Conditions  

Microsoft Academic Search

A mild, efficient and solvent-free MW-promoted Biginelli reaction for the synthesis of 3,4-dihydropyrimidin-2(1H)-(thio)ones in nitrite ionic liquid (IL-ONO) is described. This ionic liquid plays as weak Lewis base catalyst, which can be easily recovered and reused in several runs. The satisfactory results were obtained with good yields, short reaction time and simplicity in the experimental procedure.

Mortaza Mirzai; Hassan Valizadeh

2011-01-01

356

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

357

2D 1H and 3D 1H-15N NMR of zinc-rubredoxins: contributions of the beta-sheet to thermostability.  

PubMed Central

Based on 2D 1H-1H and 2D and 3D 1H-15N NMR spectroscopies, complete 1H NMR assignments are reported for zinc-containing Clostridium pasteurianum rubredoxin (Cp ZnRd). Complete 1H NMR assignments are also reported for a mutated Cp ZnRd, in which residues near the N-terminus, namely, Met 1, Lys 2, and Pro 15, have been changed to their counterparts, (-), Ala and Glu, respectively, in rubredoxin from the hyperthermophilic archaeon, Pyrococcus furiosus (Pf Rd). The secondary structure of both wild-type and mutated Cp ZnRds, as determined by NMR methods, is essentially the same. However, the NMR data indicate an extension of the three-stranded beta-sheet in the mutated Cp ZnRd to include the N-terminal Ala residue and Glu 15, as occurs in Pf Rd. The mutated Cp Rd also shows more intense NOE cross peaks, indicating stronger interactions between the strands of the beta-sheet and, in fact, throughout the mutated Rd. However, these stronger interactions do not lead to any significant increase in thermostability, and both the mutated and wild-type Cp Rds are much less thermostable than Pf Rd. These correlations strongly suggest that, contrary to a previous proposal [Blake PR et al., 1992, Protein Sci 1:1508-1521], the thermostabilization mechanism of Pf Rd is not dominated by a unique set of hydrogen bonds or electrostatic interactions involving the N-terminal strand of the beta-sheet. The NMR results also suggest that an overall tighter protein structure does not necessarily lead to increased thermostability. PMID:8732760

Richie, K. A.; Teng, Q.; Elkin, C. J.; Kurtz, D. M.

1996-01-01

358

K6irs1, K6irs2, K6irs3, and K6irs4 Represent the Inner-Root-Sheath-Specific Type II Epithelial Keratins of the Human Hair Follicle1  

Microsoft Academic Search

In this study we report on the cloning of two novel human type II keratin cDNAs, K6irs3 and K6irs4, which were specifically expressed in the inner root sheath of the hair follicle. Together with the genes of two previously described type II inner root sheath keratins, K6irs1 and K6irs2, the K6irs3 and K6irs4 genes were subclustered in the type II

Lutz Langbein; Michael A Rogers; Silke Praetzel; Hermelita Winter; Jürgen Schweizer

2003-01-01

359

Nonpeptide angiotensin II receptor antagonists. 2. Design, synthesis, and structure-activity relationships of 2-alkyl-4-(1H-pyrrol-1-yl)-1H-imidazole derivatives: profile of 2-propyl-1-[[2'-(1H-tetrazol-5-yl)-[1,1' -biphenyl]-4-yl]-methyl]-4-[2-(trifluoroacetyl)-1H-pyrrol-1-yl]-1H- imidazole-5-carboxylic acid (CI-996).  

PubMed

A novel series of nonpeptide angiotensin II (AII) receptor antagonists containing a 1H-pyrrol-1-yl moiety at the 4-position of the imidazole have been developed. The pyrrole group occupies the same lipophilic pocket at the receptor as the chloro group in DuP 753 (68) and EXP 3174 (69) and the pentafluoro group in DuP 532 (70), respectively. The impetus for its selection came from bioisosteric considerations based on hydrophobic and electronic substituent constants. An extensive study of the structure-activity relationships revealed several highly potent AII receptor antagonists. An acyl substitution at the 2-position of the pyrrole ring improved activity, most notably in the in vivo rat model. In addition, the 2-substituted pyrrole compounds improved chemical stability toward extremely facile decarboxylation reaction associated with unsubstituted pyrrole analogues, thus facilitating development of these agents. The IC50's of 18, 20, and 42 (< 1 nM) were better than the reference compounds 69 and 70, respectively. These compounds were selective AII antagonists that compete at the AT1 receptor and showed no affinity at the AT2 receptor at concentrations up to 10 microM. Upon intravenous administration in a normotensive rat model, compound 18 inhibited the AII-induced responses with ED50 of 6 micrograms/kg per min. In a renal hypertensive rat model, the antihypertensive potency of compound 18, at a dose of 10 mg/kg, was very similar to those 68 and 69, respectively. Compound 18 demonstrated a dose-related (3-30 mg/kg) decrease in blood pressure that was sustained for greater than 24 h. On the basis of its profile, compound 18, designated as CI-996, has been selected for in-depth studies. The design, synthesis, in vitro, and in vivo structure-activity relationships are described. PMID:8360871

Sircar, I; Hodges, J C; Quin, J; Bunker, A M; Winters, R T; Edmunds, J J; Kostlan, C R; Connolly, C; Kesten, S J; Hamby, J M

1993-08-01

360

The morphology dependent electrocatalytic activity of Ir nanostructures towards oxygen reduction.  

PubMed

Iridium nanostructures with different morphologies are synthesized by a simple, environmentally friendly approach in aqueous media under mild conditions. The morphology dependent electrocatalytic activity of Ir nanochains and nanoparticles towards oxygen reduction reaction (ORR) has been demonstrated in both acidic and alkaline media. Comparative electrochemical studies reveal that nanochains exhibit significantly enhanced ORR activities in both acidic and alkaline media as compared with nanoparticles, as a result of the continuous structure of interconnected particles. The mechanism of oxygen reduction on Ir nanostructures predominantly follows a four-electron pathway in alkaline and acidic solutions. Excellent stability and good selectivity towards methanol tolerance are reported. PMID:25003715

Chakrapani, Kalapu; Sampath, Srinivasan

2014-08-21

361

Low-frequency IR spectroscopy in the study of the structures of cellulose and cellulose nitrates  

NASA Astrophysics Data System (ADS)

The application of low-frequency IR spectroscopy in the structural analysis of polymers is examined. The vibrations of crystal lattices and polymer chains as well as deformation and torsional vibrations manifested in the low-frequency part of the IR spectrum are discussed. Studies in this field are reviewed critically and the experimental and theoretical data concerning the interpretation of the low-frequency spectra of monosacchrides, polysaccharides, and their nitro-derivatives are surveyed. Attention is concentrated on the establishment of 'spectrum-structure' correlations for cellulose in the course of its physical modification and chemical reactions (nitration). The bibliography includes 79 references.

Mukhamadeeva, R. M.; Zhbankov, R. G.; Sopin, Vladimir F.; Marchenko, G. N.

1993-04-01

362

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

E-print Network

into a stereotactic device. Images and 1 H MR spectra were acquired using a Varian 4.7T animal scanner together those same pathways due to the high local concentrations of Mn required to provide MRI contrast

363

Functionalized multi-walled carbon nanotubes in an aldol reaction  

NASA Astrophysics Data System (ADS)

The covalent functionalization of multi-walled carbon nanotubes (MWCNTs) with a proline-based derivative is reported. Initially, MWCNTs were oxidized in order to introduce a large number of carboxylic units on their tips followed by N-tert-butoxycarbonyl-2,2'(ethylenedioxy)bis-(ethylamine) conjugation through an amide bond. Then, a proline derivative bearing a carboxylic terminal moiety at the 4-position was coupled furnishing proline-modified MWCNTs. This new hybrid material was fully characterized by spectroscopic and microscopy means and its catalytic activity in the asymmetric aldol reaction between acetone and 4-nitrobenzaldehyde was evaluated for the first time, showing to proceed almost quantitatively in aqueous media. Furthermore, several amino-modified MWCNTs were prepared and examined in the particular aldol reaction. These new hybrid materials exhibited an enhanced catalytic activity in water, contrasting with the pristine MWCNTs as well as the parent organic molecule, which failed to catalyze the reaction efficiently. Furthermore, the modified MWCNTs proved to catalyze the aldol reaction even after three repetitive cycles. Overall, a green approach for the aldol reaction is presented, where water can be employed as the solvent and modified MWCNTs can be used as catalysts, which can be successfully recovered and reused, while their catalytic activity is retained.The covalent functionalization of multi-walled carbon nanotubes (MWCNTs) with a proline-based derivative is reported. Initially, MWCNTs were oxidized in order to introduce a large number of carboxylic units on their tips followed by N-tert-butoxycarbonyl-2,2'(ethylenedioxy)bis-(ethylamine) conjugation through an amide bond. Then, a proline derivative bearing a carboxylic terminal moiety at the 4-position was coupled furnishing proline-modified MWCNTs. This new hybrid material was fully characterized by spectroscopic and microscopy means and its catalytic activity in the asymmetric aldol reaction between acetone and 4-nitrobenzaldehyde was evaluated for the first time, showing to proceed almost quantitatively in aqueous media. Furthermore, several amino-modified MWCNTs were prepared and examined in the particular aldol reaction. These new hybrid materials exhibited an enhanced catalytic activity in water, contrasting with the pristine MWCNTs as well as the parent organic molecule, which failed to catalyze the reaction efficiently. Furthermore, the modified MWCNTs proved to catalyze the aldol reaction even after three repetitive cycles. Overall, a green approach for the aldol reaction is presented, where water can be employed as the solvent and modified MWCNTs can be used as catalysts, which can be successfully recovered and reused, while their catalytic activity is retained. Electronic supplementary information (ESI) available: Experimental details for the synthesis of 5, 8 and 11; 1H & 13C NMR of compounds 8 and 11; ATR-IR spectra, thermographs and TEM imaging of hybrids 10 and 13. See DOI: 10.1039/c4nr06543c

Chronopoulos, D. D.; Kokotos, C. G.; Karousis, N.; Kokotos, G.; Tagmatarchis, N.

2015-01-01

364

Low-energy proton capture reactions  

SciTech Connect

An overview of experimental problems in measuring the cross sections for (p,?) and (p,n) reactions at low energies is given with a specific emphasis on electron screening in metallic targets. Thick target ?-ray and neutron yields are compared for Ni and NiO targets, V and VO{sub 2} targets and Mn and MnO targets. The {sup 1}H({sup 7}Li,?){sup 4}He reaction was studied in inverse kinematics with hydrogen loaded into Pd and PdAg alloy foils from gas phase. Based on these results, a new approach to electron screening in nuclear reactions is suggested.

Lipoglavsek, M.; Cvetinovic, A.; Gajevic, J.; Likar, A.; Vavpetic, P. [Jozef Stefan Institute, Jamova ulica 39, Ljubljana (Slovenia); Petrovic, T. [Jozef Stefan Institute, Jamova ulica 39, Ljubljana, Slovenia and Cosylab d.d., Teslova ulica 30, Ljubljana (Slovenia)

2014-05-09

365

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

366

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

2005-09-26

367

1 H, 13 C and 15 N chemical shift referencing in biomolecular NMR  

Microsoft Academic Search

A considerable degree of variability exists in the way that 1H, 13C and 15N chemical shifts are reported and referenced for biomolecules. In this article we explore some of the reasons for this situation and propose guidelines for future chemical shift referencing and for conversion from many common 1H, 13C and 15N chemical shift standards, now used in biomolecular NMR,

David S. Wishart; Colin G. Bigam; Jian Yao; Frits Abildgaard; H. Jane Dyson; Eric Oldfield; John L. Markley; Brian D. Sykes

1995-01-01

368

Evidence for long-term neurotoxicity associated with methamphetamine abuse A 1H MRS study  

Microsoft Academic Search

Article abstract—Objective: To determine whether proton MRS (1H MRS) can detect long-term metabolite abnormalities in abstinent methamphetamine users. Background: Methamphetamine is toxic to dopaminergic and serotonergic neurons in rodents; however, little data are available on the toxic effects of methamphetamine on the human brain. Methods: 1H MRS was performed in 26 abstinent methamphetamine abusers with a history of methamphetamine dependence

Thomas Ernst; Linda Chang; Maria Leonido-Yee; Oliver Speck

369

[Brain metabolism alterations in patients with anorexia nervosa observed in 1H-MRS  

Microsoft Academic Search

The causes of metabolic brain changes in patients with anorexia nervosa are still not fully explained. The purpose of this study was to use the 1H-MRS method in investigating metabolic changes in the brain of patients with anorexia nervosa. We studied 10 patients for visible alternations in brain metabolism and compared the results to healthy controls. 1H-MRS was acquired by

P. Grzelak; W. Gajewicz; A. Wyszogrodzka-Kucharska; A. Rotkiewicz; L. Stefanczyk; B. M. Goraj; J. Rabe-Jablonska

2005-01-01

370

Combined 17 O\\/ 1 H MRI study in a whole-body scanner  

Microsoft Academic Search

A simple method of obtaining consecutive1H and natural-abundance17O images is described with a scanner’s original body resonator (for1H) and a homemade linear birdcage (for17O). Two kinds of experiments were performed to test the method. In the first experiment, a proton image of the phantom was\\u000a acquired with a whole-body resonator. In the second experiment, the phantom was inserted into an

M. Kempka; J. Hankiewicz; D. Fiat

2003-01-01

371

Reduction in hypothalamic 1H-MRS metabolite ratios in patients with cluster headache  

Microsoft Academic Search

Objective: To determine the 1H-MR spectroscopic (MRS) findings in the hypothalamus in patients with episodic cluster headache.Methods: 47 patients were recruited with episodic cluster headache (35 in cluster period and 12 in remission), 21 normal controls, and 16 patients with chronic migraine. The hypothalamic 1H-MRS metabolite ratio changes in patients with cluster headache were evaluated and compared with results in

S-J Wang; J-F Lirng; J-L Fuh; J-J Chen

2006-01-01

372

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.

2012-06-26

373

Named Reactions  

NSDL National Science Digital Library

This Web site lists 95 of the most important named reactions in organic chemistry. Each is linked to a Web page that gives the primary reference and equations for one or more recent literature examples that illustrate the use of the reaction.

374

Xanthan Gum Removal for 1H-NMR Analysis of the Intracellular Metabolome of the Bacteria Xanthomonas axonopodis pv. citri 306  

PubMed Central

Xanthomonas is a genus of phytopathogenic bacteria, which produces a slimy, polysaccharide matrix known as xanthan gum, which involves, protects and helps the bacteria during host colonization. Although broadly used as a stabilizer and thickener in the cosmetic and food industries, xanthan gum can be a troubling artifact in molecular investigations due to its rheological properties. In particular, a cross-reaction between reference compounds and the xanthan gum could compromise metabolic quantification by NMR spectroscopy. Aiming at an efficient gum extraction protocol, for a 1H-NMR-based metabolic profiling study of Xanthomonas, we tested four different interventions on the broadly used methanol-chloroform extraction protocol for the intracellular metabolic contents observation. Lower limits for bacterial pellet volumes for extraction were also probed, and a strategy is illustrated with an initial analysis of X. citri’s metabolism by 1H-NMR spectroscopy. PMID:24957023

Pegos, Vanessa R.; Canevarolo, Rafael R.; Sampaio, Aline P.; Balan, Andrea; Zeri, Ana C. M.

2014-01-01

375

Melas Chasma in IR Color  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

Released August 11, 2004 This image shows two representations of the same infra-red image over Melas Chasma. 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.

There is a distinct purple/blue layer present in the northern wall of the Chasma. Although this layer likely has a composition different than the surrounding areas, it is difficult to interpret its specific composition due to the high variability of sunlit and shaded surfaces in this area, which cause a wide range of temperatures to be present within each pixel of the image. It is possible that this layer has a unique composition due to differences in the volcanic or sedimentary environment at the time that the rock formed, or it could be a layer of magma injected between two previously existing rock layers. Another possibility is that the wall is mostly covered by dust and debris, and this portion contains the only exposed bedrock. The light blue colors present in many other areas of the Chasma are due to water ice clouds.

Image information: IR instrument. Latitude -8.9, Longitude 282 East (78 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

376

Basaltic Crater in Color IR  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

Released August 6, 2004 This image shows two representations of the same infra-red image near Nili Fosse in the the Isidis region of Mars. 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 many cases craters trap sand in their topographic depressions, interrupting the sand's migration across the Martian surface. This image is particularly interesting because there appears to be more than 1 type of sand in the bottom of this crater and in the hummocky terrain near the bottom of the image. The pink/magenta areas are characteristic of a basaltic composition, but there are also orange areas that are likely caused by the presence of andesite. These two compositions, basalt and andesite, are some of the most common found on Mars.

Image information: IR instrument. Latitude 24, Longitude 80.7 East (297.3 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

377

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 ...

Mrs. Hicken

2009-05-04

378

Development of Ir-base refractory superalloys  

Microsoft Academic Search

In the present study the authors propose a new class of superalloys: refractory superalloys. This new concept is defined as alloys with γ-fcc and γâ²-L1â phases coherent structures similar to Ni-base superalloys, and yet with considerably higher melting points. Ir, having a melting point of 2,443 C, is selected as the base metal for the refractory superalloys since Ir has

Y. Yamabe; Y. Koizumi; H. Murakami; Y. Ro; T. Maruko; H. Harada

1996-01-01

379

Active IR-applications in civil engineering  

Microsoft Academic Search

Applications of IR-thermography in civil engineering are not limited to the identification of heat losses in building envelopes. As it is well known from other areas of non-destructive testing, active IR-thermographic methods such as cooling down or lock-in thermography improves the results in many investigations. In civil engineering these techniques have not been used widely. Mostly thermography is used in

H. Wiggenhauser

2002-01-01

380

Endothelial necrosis at 1h post-burn predicts progression of tissue injury  

PubMed Central

Burn injury progression has not been well characterized at the cellular level. To define burn injury progression in terms of cell death, histopathologic spatiotemporal relationships of cellular necrosis and apoptosis were investigated in a validated porcine model of vertical burn injury progression. Cell necrosis was identified by High Mobility Group Box 1 protein and apoptosis by Caspase 3a staining of tissue samples taken 1h, 24h and 7 days post-burn. Level of endothelial cell necrosis at 1h was predictive of level of apoptosis at 24h (Pearson's r=0.87) and of level of tissue necrosis at 7 days (Pearson's r=0.87). Furthermore, endothelial cell necrosis was deeper than interstitial cell necrosis at 1h (p<0.001). Endothelial cell necrosis at 1h divided the zone of injury progression (Jackson's zone of stasis) into an upper subzone with necrotic endothelial cells and initially viable adnexal and interstitial cells at 1h that progressed to necrosis by 24h, and a lower zone with initially viable endothelial cells at 1h, but necrosis and apoptosis of all cell types by 24h. Importantly, this spatiotemporal series of events and rapid progression resembles myocardial infarction and stroke, and implicates mechanisms of these injuries, ischemia, ischemia reperfusion, and programmed cell death, in burn progression. PMID:23627744

Hirth, Douglas; McClain, Steve A.; Singer, Adam J.; Clark, Richard A.F.

2013-01-01

381

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

382

Experimental and DFT studies on the vibrational and electronic spectra of 2-(1H-Imidazo [4,5-ƒ][1,10]phenanthrolin-2-yl)phenol  

NASA Astrophysics Data System (ADS)

The compound 2-(1H-Imidazo [4,5-ƒ][1,10] phenanthrolin-2-yl) phenol (IPP) was synthesized, followed by structure determination by X-ray diffraction, the results of which agree well with the calculated optimized, lowest energy geometrical structure. Vibrational information was obtained by FT-IR and Raman spectroscopy which also agree well with calculations (of harmonic vibration frequencies). The calculations were carried out with density functional theory B3LYP methods using 6-311G** and LANL2DZ basis sets. Absorption UV-Vis experiments of IPP in CH3OH solution reveal three maximum peaks at 237.0, 274.0 and 335.0 nm, which are in agreement with calculated electronic transitions using TD-B3LYP/6-311G** in CH3OH solution, and agree to a lesser extent with gas-phase calculations.

Tang, Tingting; Tang, Guodong; Kou, ShanShan; Zhao, Jianyin; Culnane, Lance F.; Zhang, Yu

2014-01-01

383

Complete assignment of the 1H and 13C NMR spectra of garciniaphenone and keto-enol equilibrium statements for prenylated benzophenones.  

PubMed

This article reports the structural elucidation by IR, UV and MS spectroscopic data along with 1H and 13C NMR chemical shift assignments of two benzophenones isolated from the fruit pericarp of Garcinia brasiliensis Mart. (Clusiaceae): garciniaphenone, (1R,5S,7S)-3-benzoyl-4-hydroxy-6,6-dimethyl-5,7-di(3-methyl-2-butenyl)bicyclo[3.3.1]non-3-ene-2,9-dione, a novel triprenylated benzophenone; and 7-epi-clusianone, a tetraprenylated benzophenone that has already been extracted from another species of the same family. Furthermore, the keto-enol tautomeric equilibrium at solution-state was described for these compounds by 1D and 2D NMR spectral methods and one attempt to rationalize the different ratios between the noted tautomers was based on stereochemical features. PMID:18236418

Derogis, Priscilla B M C; Martins, Felipe T; de Souza, Thiago C; de C Moreira, Maria E; Souza Filho, José D; Doriguetto, Antonio C; de Souza, Kamila R D; Veloso, Marcia P; Dos Santos, Marcelo H

2008-03-01

384

Enhancing the photoluminescence of 1-(naphthalene-1-yl)-2,4,5-triphenyl-1H-imidazole anchored to superparamagnetic nanoparticles  

NASA Astrophysics Data System (ADS)

Synthesis and characterization of 1-(naphthalene-1-yl)-2,4,5-triphenyl-1H-imidazole has been carried out by spectral studies. The synthesized phosphated imidazole and phosphated imidazole bound magnetic nanoparticles were characterized using fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and powder X-ray diffraction (XRD). The photophysical characteristics of the synthesized phosphated imidazole and phosphated imidazole bound magnetic nanoparticles were investigated by steady-state absorption and emission spectra as well as time resolved fluorometry. The intensities of absorption and emission maxima increase in the following order, phosphated imidazole bound Fe2O3 > phosphated imidazole > imidazole.

Jayabharathi, J.; Karunakaran, C.; Kalaiarasi, V.; Ramanathan, P.; Prabhakaran, A.

2015-01-01

385

Experimental and DFT studies on the vibrational and electronic spectra of 2-(4,5-phenyl-1H-imidazole-2-yl)-phenol  

NASA Astrophysics Data System (ADS)

The compound 2-(4,5-phenyl-1H-imidazole-2-yl-phenol (PIP) was synthesized, followed by structure determination by X-ray diffraction, the results of which agree well with the calculated optimized, lowest energy geometrical structure. Vibrational information was obtained by FT-IR and Raman spectroscopy which also agree well with calculations (of harmonic vibration frequencies). The calculations were carried out with density functional theory B3LYP methods using 6-311++G** and LANL2DZ basis sets. Absorption UV-Vis experiments of PIP in CH3CH2OH solution reveal three maximum peaks at 245, 292 and 317 nm, which are in agreement with calculated electronic transitions using TD-B3LYP/6-311++G** in CH3CH2OH solution, and agree to the gas-phase calculations.

Ye, Yunfeng; Tang, Guodong; Tang, Tingting; Culnane, Lance F.; Zhao, Jianyin; Zhang, Yu

2015-02-01

386

(1-Methyl-2-(thiophen-2-yl)-1H-benzo[d]imidazole) and its three copper complexes: Synthesis, characterization and fluorescence properties  

NASA Astrophysics Data System (ADS)

(1-Methyl-2-(thiophen-2-yl)-1H-benzo[d]imidazole) (C12H10N2S) (L) ligand and its three copper complexes [(Cu2(L)2I2] (1), [(Cu(L)2X2] (X = Cl- (2), and NO3- (3)) were synthesized and characterized by elemental analysis and IR measurements. The structures of the complexes 1-3 were determined by single crystal X-ray diffraction. The complex molecules interact with each other's via weak Csbnd H⋯X hydrogen bonds (X = I for the complex 1, X = Cl for the complex 2 and X = O for the complex 3). Upon excitation with a wavelength of 350 nm at room temperature, free L and complex 1 emit fluorescence at 420 and 560 nm, respectively.

Demir, Selçuk; Eren, Bilge; Ho?y?ska, Ma?gorzata

2015-02-01

387

Near-IR/Optical Monitoring Program of the Arecibo Sample of OH/IR Stars  

NASA Astrophysics Data System (ADS)

We performed a near-IR/optical monitoring program from 1999 to 2005 in order to study the variability properties of the `Arecibo sample of OH/IR stars' (periods, amplitudes, and color variations). Here we describe this multi-wavelength long-term monitoring program. Data analysis is still in process. Our ultimate goal is to study in particular the oxygen-rich AGB stars with M > 2 M?, 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.

Jiménez-Esteban, F.; Engels, D.; García-Lario, P.

2007-11-01

388

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

2006-11-02

389

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

390

Measurements of the ^1H(^18F,p)^18F and ^1H(^18F,?)^15O Excitation Functions at the HRIBF  

NASA Astrophysics Data System (ADS)

Knowledge of the astrophysical ^18F(p,?)^15O rate is important for understanding gamma-ray emission from novae and heavy-element production in x-ray bursts. A state with Ex ~= 7.075 MeV in ^19Ne provides an s-wave resonance and, depending on its properties, could dominate the ^18F(p,?)^15O rate. By simultaneously measuring the ^1H(^18F,p)^18F and ^1H(^18F,?)^15O excitation functions with a radioactive ^18F beam at ORNL's Holifield Radioactive Ion Beam Facility, we have resolved discrepancies(Utku et al.), Phys. Rev. C57, 2731 (1998).^,(Coszach et al.), Phys. Lett. B353, 184 (1995).^,(Rehm et al.), Phys. Rev. C52, R460 (1995); 53, 1950 (1996). in the properties of this astrophysically-important state. Our results will be presented.

Bardayan, D. W.; Blackmon, J. C.; Smith, M. S.; Bradfield-Smith, W.; Lewis, R.; Parker, P. D.; Visser, D. W.; Brune, C. R.; Champagne, A. E.; Johnson, B. A.; Kozub, R. L.; Davinson, T.; Shotter, A. C.; Woods, P. J.; Lee, C. S.

2000-10-01

391

Analysis of illegally manufactured formulations of tadalafil (Cialis ®) by 1H NMR, 2D DOSY 1H NMR and Raman spectroscopy  

Microsoft Academic Search

Counterfeit and\\/or imitation medicines are becoming a major health problem not only in developing countries but also in wealthier countries. The need of new and easy analytical methods for quality control of drugs is essential. We describe the use of Raman spectroscopy, 1H nuclear magnetic resonance (NMR) and 2D diffusion-ordered spectroscopy (DOSY) NMR to analyse genuine Cialis® and seven illegally

Saleh Trefi; Corinne Routaboul; Saleh Hamieh; Véronique Gilard; Myriam Malet-Martino; Robert Martino

2008-01-01

392

Enhanced blocking temperature in (Pt/Co)3/IrMn/Co and (Pd/Co)3/IrMn/Co trilayers with ultrathin IrMn layer  

NASA Astrophysics Data System (ADS)

IrMn blocking temperature (TB) is compared between IrMn/Co bilayers and (Pt/Co)3/IrMn/Co and (Pd/Co)3/IrMn/Co trilayers for different IrMn thicknesses. Exchange bias field (Hex) is measured from 5 to 400 K. Trilayers show a more concave thermal decrease of Hex(T) compared to bilayers and, for thin IrMn layers, larger TB and sharper peak of coercive field Hc around TB. This Hex(T) behaviour presents improved characteristics for thermally assisted-MRAM (TA-MRAM) applications, with large Hex/Hc ratio. Two physical explanations are proposed: an indirect IrMn intergrain coupling through the (Pt(Pd)/Co)3 layer and a reduction of IrMn/Co interfacial coupling due to out-of-plane canting of the IrMn spins.

Vinai, G.; Moritz, J.; Bandiera, S.; Prejbeanu, I. L.; Dieny, B.

2013-08-01

393

14N quadrupole resonance and 1H T1 dispersion in the explosive RDX.  

PubMed

The explosive hexahydro-1,3,5-trinitro-s-triazine (CH2-N-NO2)3, commonly known as RDX, has been studied by 14N NQR and 1H NMR. NQR frequencies and relaxation times for the three ?+ and ?- lines of the ring 14N nuclei have been measured over the temperature range 230-330 K. The 1H NMR T1 dispersion has been measured for magnetic fields corresponding to the 1H NMR frequency range of 0-5.4 M Hz. The results have been interpreted as due to hindered rotation of the NO2 group about the N-NO2 bond with an activation energy close to 92 kJ mol(-1). Three dips in the 1H NMR dispersion near 120, 390 and 510 kHz are assigned to the ?0, ?- and ?+ transitions of the 14NO2 group. The temperature dependence of the inverse line-width parameters T2? of the three ?+ and ?- ring nitrogen transitions between 230 and 320 K can be explained by a distribution in the torsional oscillational amplitudes of the NO2 group about the N-NO2 bond at crystal defects whose values are consistent with the latter being mainly edge dislocations or impurities in the samples studied. Above 310 K, the 14N line widths are dominated by the rapid decrease in the spin-spin relaxation time T2 due to hindered rotation of the NO2 group. A consequence of this is that above this temperature, the 1H T1 values at the quadrupole dips are dominated by the spin mixing time between the 1H Zeeman levels and the combined 1H and 14N spin-spin levels. PMID:21978662

Smith, John A S; Blanz, Martin; Rayner, Timothy J; Rowe, Michael D; Bedford, Simon; Althoefer, Kaspar

2011-12-01

394

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 ...

395

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.

Maryland Virtual High School

396

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

397

Experimental and DFT study on a newly synthesized ethyl 2-cyano-3-[5-(phenyl-hydrazonomethyl)-1H-pyrrol-2-yl]-acrylate  

NASA Astrophysics Data System (ADS)

A newly synthesized ethyl 2-cyano-3-[5-(phenyl-hydrazonomethyl)-1H-pyrrol-2-yl]-acrylate (ECPHPA) has been characterized by experimental measurements. The theoretically calculated results are in accordance with the experimental studies. All calculations have been performed using B3LY/6-31G(d,p) basis set. The oscillatory strength (f) and wavelength of various electronic excitations show ? ? ?? nature of transitions. Natural bond orbital (NBO) analysis shows intramolecular conjugative/hyperconjugative interactions within the studied molecule. The result of hydrogen bonding is obvious in 1H NMR, FT-IR and NBO analyses as down field chemical shift, vibrational red shift and ?1(C8sbnd N9) ? ??(N1sbnd H24) interaction, respectively. Global electrophilicity index (? = 4.80 eV) shows that ECPHPA is a strong electrophile and local reactivity descriptors indicate have reactive sites within molecule and undergo for the formation of various heterocyclic compounds. The first hyperpolarizability (?0) computed found to be 35.76 × 10-30 esu, evaluate the suitability of compound for non-linear optical (NLO) response.

Rawat, Poonam; Singh, R. N.

2015-02-01

398

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

PubMed

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. PMID:24892534

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

2014-11-11

399

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

400

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

401

Imaging, Diagnosis, Prognosis Near IR Heptamethine Cyanine DyeMediated  

E-print Network

Imaging, Diagnosis, Prognosis Near IR Heptamethine Cyanine Dye­Mediated Cancer Imaging Xiaojian hepatamethine cyanine dyes, IR-783 and MHI-148, in tumor cells and tissues. Experimental Design: IR-783 and MHI normal cells in blood. Results: These near-IR hepatamethine cyanine dyes were retained in cancer cells

Cheng, Jianjun

402

IGF-IR Targeted Therapy: Past, Present and Future  

PubMed Central

The IGF-I receptor (IGF-IR) has been studied as an anti-cancer target. However, monotherapy trials with IGF-IR targeted antibodies or with IGF-IR specific tyrosine kinase inhibitors have, overall, been very disappointing in the clinical setting. This review discusses potential reasons why IGF-I R targeted therapy fails to inhibit growth of human cancers. It has become clear that intracellular signaling pathways are highly interconnected and complex instead of being linear and simple. One of the most potent candidates for failure of IGF-IR targeted therapy is the insulin receptor isoform A (IR-A). Activation of the IR-A by insulin-like growth factor-II (IGF-II) bypasses the IGF-IR and its inhibition. Another factor may be that anti-cancer treatment may reduce IGF-IR expression. IGF-IR blocking drugs may also induce hyperglycemia and hyperinsulinemia, which may further stimulate cell growth. In addition, circulating IGF-IRs may reduce therapeutic effects of IGF-IR targeted therapy. Nevertheless, it is still possible that the IGF-IR may be a useful adjuvant or secondary target for the treatment of human cancers. Development of functional inhibitors that affect the IGF-IR and IR-A may be necessary to overcome resistance and to make IGF-IR targeted therapy successful. Drugs that modify alternative downstream effects of the IGF-IR, so called “biasing agonists,” should also be considered. PMID:25566194

Janssen, Joseph A. M. J. L.; Varewijck, Aimee J.

2014-01-01

403

1H relaxation dispersion in solutions of nitroxide radicals: Influence of electron spin relaxation  

NASA Astrophysics Data System (ADS)

The work presents a theory of nuclear (1H) spin-lattice relaxation dispersion for solutions of 15N and 14N radicals, including electron spin relaxation effects. The theory is a generalization of the approach presented by Kruk et al. [J. Chem. Phys. 137, 044512 (2012)], 10.1063/1.4736854. The electron spin relaxation is attributed to the anisotropic part of the electron spin-nitrogen spin hyperfine interaction modulated by rotational dynamics of the paramagnetic molecule, and described by means of Redfield relaxation theory. The 1H relaxation is caused by electron spin-proton spin dipole-dipole interactions which are modulated by relative translational motion of the solvent and solute molecules. The spectral density characterizing the translational dynamics is described by the force-free-hard-sphere model. The electronic relaxation influences the 1H relaxation by contributing to the fluctuations of the inter-molecular dipolar interactions. The developed theory is tested against 1H spin-lattice relaxation dispersion data for glycerol solutions of 4-oxo-TEMPO-d16-15N and 4-oxo-TEMPO-d16-14N covering the frequency range of 10 kHz-20 MHz. The studies are carried out as a function of temperature starting at 328 K and going down to 290 K. The theory gives a consistent overall interpretation of the experimental data for both 14N and 15N systems and explains the features of 1H relaxation dispersion resulting from the electron spin relaxation.

Kruk, D.; Korpa?a, A.; Kubica, A.; Kowalewski, J.; Rössler, E. A.; Moscicki, J.

2013-03-01

404

Urinary metabolic fingerprint of acute intermittent porphyria analyzed by (1)H NMR spectroscopy.  

PubMed

(1)H NMR is a nonbiased technique for the quantification of small molecules that could result in the identification and characterization of potential biomarkers with prognostic value and contribute to better understand pathophysiology of diseases. In this study, we used (1)H NMR spectroscopy to analyze the urinary metabolome of patients with acute intermittent porphyria (AIP), an inherited metabolic disorder of heme biosynthesis in which an accumulation of the heme precursors 5-aminolaevulinic acid (ALA) and porphobilinogen (PBG) promotes sudden neurovisceral attacks, which can be life-threatening. Our objectives were (1) to demonstrate the usefulness of (1)H NMR to identify and quantify ALA and PBG in urines from AIP patients and (2) to identify metabolites that would predict the response to AIP crisis treatment and reflect differential metabolic reprogramming. Our results indicate that (1)H NMR can help to diagnose AIP attacks based on the identification of ALA and PBG. We also show that glycin concentration increases in urines from patients with frequent recurrences at the end of the treatment, after an initial decrease, whereas PBG concentration remains low. Although the reasons for this altered are elusive, these findings indicate that a glycin metabolic reprogramming occurs in AIPr patients and is associated with recurrence. Our results validate the proof of concept of the usefulness of (1)H NMR spectroscopy in clinical chemistry for the diagnosis of acute attack of AIP and identify urinary glycin as a potential marker of recurrence of AIP acute attacks. PMID:24437734

Carichon, Mickael; Pallet, Nicolas; Schmitt, Caroline; Lefebvre, Thibaud; Gouya, Laurent; Talbi, Neila; Deybach, Jean Charles; Beaune, Philippe; Vasos, Paul; Puy, Hervé; Bertho, Gildas

2014-02-18

405

Iridium Interfacial Stack - IrIS  

NASA Technical Reports Server (NTRS)

Iridium Interfacial Stack (IrIS) is the sputter deposition of high-purity tantalum silicide (TaSi2-400 nm)/platinum (Pt-200 nm)/iridium (Ir-200 nm)/platinum (Pt-200 nm) in an ultra-high vacuum system followed by a 600 C anneal in nitrogen for 30 minutes. IrIS simultaneously acts as both a bond metal and a diffusion barrier. This bondable metallization that also acts as a diffusion barrier can prevent oxygen from air and gold from the wire-bond from infiltrating silicon carbide (SiC) monolithically integrated circuits (ICs) operating above 500 C in air for over 1,000 hours. This TaSi2/Pt/Ir/Pt metallization is easily bonded for electrical connection to off-chip circuitry and does not require extra anneals or masking steps. There are two ways that IrIS can be used in SiC ICs for applications above 500 C: it can be put directly on a SiC ohmic contact metal, such as Ti, or be used as a bond metal residing on top of an interconnect metal. For simplicity, only the use as a bond metal is discussed. The layer thickness ratio of TaSi2 to the first Pt layer deposited thereon should be 2:1. This will allow Si from the TaSi2 to react with the Pt to form Pt2Si during the 600 C anneal carried out after all layers have been deposited. The Ir layer does not readily form a silicide at 600 C, and thereby prevents the Si from migrating into the top-most Pt layer during future anneals and high-temperature IC operation. The second (i.e., top-most) deposited Pt layer needs to be about 200 nm to enable easy wire bonding. The thickness of 200 nm for Ir was chosen for initial experiments; further optimization of the Ir layer thickness may be possible via further experimentation. Ir itself is not easily wire-bonded because of its hardness and much higher melting point than Pt. Below the iridium layer, the TaSi2 and Pt react and form desired Pt2Si during the post-deposition anneal while above the iridium layer remains pure Pt as desired to facilitate easy and strong wire-bonding to the SiC chip circuitry.

Spry, David

2012-01-01

406

Quantitative 1H nuclear magnetic resonance metabolite profiling as a functional genomics platform to investigate alkaloid biosynthesis in opium poppy.  

PubMed

Opium poppy (Papaver somniferum) produces a diverse array of bioactive benzylisoquinoline alkaloids and has emerged as a versatile model system to study plant alkaloid metabolism. The plant is widely cultivated as the only commercial source of the narcotic analgesics morphine and codeine. Variations in plant secondary metabolism as a result of genetic diversity are often associated with perturbations in other metabolic pathways. As part of a functional genomics platform, we used (1)H nuclear magnetic resonance (NMR) metabolite profiling for the analysis of primary and secondary metabolism in opium poppy. Aqueous and chloroform extracts of six different opium poppy cultivars were subjected to chemometric analysis. Principle component analysis of the (1)H NMR spectra for latex extracts clearly distinguished two varieties, including a low-alkaloid variety and a high-thebaine, low-morphine cultivar. Distinction was also made between pharmaceutical-grade opium poppy cultivars and a condiment variety. Such phenotypic differences were not observed in root extracts. Loading plots confirmed that morphinan alkaloids contributed predominantly to the variance in latex extracts. Quantification of 34 root and 21 latex metabolites, performed using Chenomx NMR Suite version 4.6, showed major differences in the accumulation of specific alkaloids in the latex of the low-alkaloid and high-thebaine, low-morphine varieties. Relatively few differences were found in the levels of other metabolites, indicating that the variation was specific for alkaloid metabolism. Exceptions in the low-alkaloid cultivar included an increased accumulation of the alkaloid precursor tyramine and reduced levels of sucrose, some amino acids, and malate. Real-time polymerase chain reaction analysis of 42 genes involved in primary and secondary metabolism showed differential gene expression mainly associated with alkaloid biosynthesis. Reduced alkaloid levels in the condiment variety were associated with the reduced abundance of transcripts encoding several alkaloid biosynthetic enzymes. PMID:18550684

Hagel, Jillian M; Weljie, Aalim M; Vogel, Hans J; Facchini, Peter J

2008-08-01

407

Systematic modeling for the insulin signaling network mediated by IRS1 and IRS2  

E-print Network

in mammalian systems. A major function of the liver is to maintain glucose homeostasis under different signaling mediated by insulin receptor substrates IRS1 and IRS2 plays a central role in maintaining glucose homeostasis under different physiological conditions. Although functions of individual components

Liu, Di "Richard"

408

40 CFR 721.4468 - 1H-Imidazole, 2-ethyl-4,5-dihydro-4-methyl-.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false 1H-Imidazole, 2-ethyl-4,5-dihydro-4-methyl...Chemical Substances § 721.4468 1H-Imidazole, 2-ethyl-4,5-dihydro-4-methyl...chemical substance identified as 1H-imidazole,...

2010-07-01

409

Synthesis and antiviral activity of 4,4?-(arylmethylene)bis(1 H-pyrazol-5-ols) against peste des petits ruminant virus (PPRV)  

Microsoft Academic Search

An efficient and eco-friendly method for the synthesis of 4,4?-(arylmethylene)bis(1H-pyrazol-5-ols) has been accomplished by tandem Knoevenagel–Michael reaction of two equivalents of 5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one with various aromatic aldehydes catalyzed by ceric ammonium nitrate (CAN) in water. All the synthesized compounds 3a–j were evaluated for in vitro antiviral activity against peste des petits ruminant virus (PPRV). Compound 3i emerged as the most interesting

Kuppusamy Sujatha; Gnanamani Shanthi; Nagarajan Panneer Selvam; Seeralan Manoharan; Paramasivan T. Perumal; Melani Rajendran

2009-01-01

410

Synthesis of Highly Stable 1,3-Diaryl-1H-1,2,3-triazol-5-ylidenes and their Applications in Ruthenium-Catalyzed Olefin Metathesis  

PubMed Central

The formal cycloaddition between 1,3-diaza-2-azoniaallene salts and alkynes or alkyne equivalents provides an efficient synthesis of 1,3-diaryl-1H-1,2,3-triazolium salts, the direct precursors of 1,2,3-triazol-5-ylidenes. These N,N-diarylated mesoionic carbenes (MICs) exhibit enhanced stability in comparison to their alkylated counterparts. Experimental and computational results confirm that these MICs act as strongly electron-donating ligands. Their increased stability allows for the preparation of ruthenium olefin metathesis catalysts that are efficient in both ring-opening and ring-closing reactions. PMID:21572542

Bouffard, Jean; Keitz, Benjamin K.; Tonner, Ralf; Lavallo, Vincent; Guisado-Barrios, Gregorio; Frenking, Gernot

2011-01-01

411

Gold-catalyzed cycloisomerization of 1,6-diyne carbonates and esters to 2,4a-dihydro-1H-fluorenes.  

PubMed

A synthetic method to prepare 2,4a-dihydro-1H-fluorenes efficiently from gold(I)-catalyzed 1,2-acyloxy migration/cyclopropenation/Nazarov cyclization of 1,6-diyne carbonates and esters is described. The suggested reaction pathway provides rare examples of [2,3]-sigmatropic rearrangement in this class of compounds as well as the involvement of an in situ formed cyclopropene intermediate in gold catalysis. Experimental and ONIOM(QM:QM') [our own n-layered integrated molecular orbital and molecular mechanics(quantum mechanics:quantum mechanics')] computational studies based on the proposed Au carbenoid species provide insight into this unique selectivity. PMID:23627597

Rao, Weidong; Koh, Ming Joo; Li, Dan; Hirao, Hajime; Chan, Philip Wai Hong

2013-05-29

412

Analyzing powers for {sup 1}H{searrow}({pi}{sup +},{pi}{sup +}{ital p}) at {ital T}{sub {pi}}=165 and 240 MeV  

SciTech Connect

We have measured the analyzing power for elastic scattering of {pi}{sup +} from a target of polarized {sup 1}H. Data were taken for incident pion beam energies of 165 and 240 MeV at several pion scattering angles. The current data generally agree with previously existing measurements of {ital A}{sub {ital y}} for this reaction and also with results of the SAID phase-shift analysis program. In most cases the new data are of higher precision than previously existing data. {copyright} {ital 1996 The American Physical Society.}

Raue, B.A.; Greco, T.A.; Khayat, M.G.; Adimi, F.; Brandt, B.v.; Breuer, H.; Chang, T.; Chant, N.S.; Chen, H.; Dooling, T.A.; Dvoredsky, A.P.; Flanders, B.S.; Gu, T.; Haas, J.P.; Hautle, P.; Huffman, J.; Kelly, J.J.; Klein, A.; Koch, K.; Konter, J.A.; Kovalev, A.I.; Kyle, G.S.; Lawrie, J.J.; Lin, Z.; Mango, S.; Markowitz, P.; Meier, R.; Payerle, T.; Ritt, S.; Roos, P.G.; Wang, M. [Old Dominion University, Norfolk, Virginia 23529 (United States)] [Old Dominion University, Norfolk, Virginia 23529 (United States); [University of Maryland, College Park, Maryland 20742 (United States); [University of Karlsruhe, Karlsruhe (Germany); [New Mexico State University, Las Cruces, New Mexico 88003 (United States); [Towson State University, Towson, Maryland 21204 (United States); [American University, Washington, D.C. 20016 (United States); [Paul Scherrer Institute, CH-4232 Villigen PSI (Switzerland); [National Accelerator Centre, Faure (South Africa)

1996-02-01

413

An eco-friendly procedure for the efficient synthesis of arylidinemalononitriles and 4,4?-(arylmethylene)bis(3-methyl-1-phenyl-1H-pyrazol-5-ols) in aqueous media  

Microsoft Academic Search

Commercially available lithium hydroxide monohydrate (LiOH·H2O) was found to be a novel “dual activation” catalyst for Knoevenagel condensation between malononitrile (1) or 3-methyl 1-phenyl-1H-pyrazol-5-(4H)-one (6) with aromatic aldehydes 2a–e leading to an efficient and easy synthesis of arylidenemalononitriles 3a–d and 4,4?-(arylmethylene)bis(3-methyl-1-phenyl-1H-pyrazol-5-ols) 7a–c in short times. The reaction of aryl aldehydes with malononitrile afforded excellent yields after 1–6 min in aqueous

Moustafa A. Gouda; Ameen A. Abu-Hashem

2012-01-01

414

Synthesis, crystal structure, computational study of 1-(6-chloro-pyridin-2-yl)-5-hydroxy-1H-pyrazole-3-carboxylic acid methyl ester and its 5-acetoxy analogs  

NASA Astrophysics Data System (ADS)

Two new pyrazole derivatives of 1-(6-chloro-pyridin-2-yl)-5-hydroxy-1H-pyrazole-3-carboxylic acid methyl ester 1a and 5-acetoxy-1-(6-chloro-pyridin-2-yl)-1H-pyrazole-3-carboxylic acid methyl ester 2 were synthesized and characterized by 1H, 13C NMR, IR spectroscopies and HRMS analyses. The molecular structure of 1a and 2 were studied by X-ray diffraction and compared to density-functional-theory (DFT) calculations. The gauge-including atomic orbital (GIAO) method for calculating 1H and 13C NMR nuclear magnetic shielding tensors at the DFT method with 6-31+G* basis set were applied to the compounds 1a and 2. Additionally, thermodynamic properties of the cyclization of the compound 3 to these compounds (1a, 1b, 1c, 4) were investigated by theoretical calculations. These theoretical calculations was shown that the compound 1a was readily formed and was the most stable one. Tautomeric forms of the compound 1a were optimized at the same methods and basis set. The calculated relative Gibbs free energies of the tautomeric forms of 1a were used to estimate the equilibrium constants. It was shown that the 1a was the most stable than tautomer of 1b and 1c in the gas phase.

Shen, Li-Qun; Huang, Su-Yu; Diao, Kai-Sheng; Lei, Fu-Hou

2012-08-01

415

Superconducting squid amplifiers for IR detectors and other applications: Phase 2. Final report. [IR (Infrared)  

SciTech Connect

The subject of this report is a completed Phase II SBIR project to develop a superconducting analog multiplexer circuit. The intended application of the multiplexer is as a component of processing circuitry for a superconducting infrared focal plane array (IR FPA). Development of the IR FPA is in progress under a separate contract. Among the accomplishments that are described below is the fabrication and testing of a functioning, superconducting, 20-input multiplexer, appropriate for use with an IR FPA. The motivation for developing a superconducting multiplexer circuit derives primarily from the significant potential advantages of an all-superconducting IR FPA system, i.e. a system in which the detectors, as well as the associated processing circuitry, are superconducting. Section III of this report reviews the subject of superconducting IR FPAs. Chief among the advantages of such systems is the potential for larger arrays with greater numbers of detectors than is now possible.

Osterman, D.

1993-05-01

416

Growth of CaIrO3 and Gd2Ir2O7 by MBE  

NASA Astrophysics Data System (ADS)

Recently, it was pointed out that the 5d transition metal iridium oxides (iridates) are promising candidates to realize topological insulators, which provide a unique platform in studying the interplay of Coulomb interactions, spin-orbit coupling, and the band topology of solids. We successfully grew epitaxial perovskite CaIrO3 and pyrochlore Gd2Ir2O7 films by reactive molecular-beam epitaxy (MBE). A range of biaxial strains for epitaxial CaIrO3 films was achieved by growing on different substrates. Angle-resolved photoemission spectroscopy (ARPES) will be used to investigate the electronic structure of the epitaxial CaIrO3 and Gd2Ir2O7 films.

Nie, Yuefeng; Held, Rainer; Chatterjee, Shouvik; Monkman, Eric; Shai, Daniel; Harter, John; Burganov, Bulat; Adamo, Carolina; Schlom, Darrell; Shen, Kyle

2012-02-01

417

IR double-resonance spectroscopy applied to the 4-aminophenol(H2O)1 cluster  

NASA Astrophysics Data System (ADS)

The IR double-resonance techniques IR/R2PI (infrared/resonant 2-photon ionization), IR/PIRI (infrared-photo-induced Rydberg ionization) and IR-photodissociation spectroscopy are valuable tools to investigate structure, vibrations, and dynamical processes of neutral and ionic hydrogen-bonded clusters containing aromatic molecules. In this paper we report on the application of the IR double-resonance techniques to determine the NH and OH stretching vibrations of 4-aminophenol and 4-aminophenol(H2O)1, both in the neutral (S0) and ionic (D0) ground state. All vibrational frequencies obtained for 4-aminophenol and the cluster are compared with the values obtained from ab initio and DFT calculations. In the S0 state, a trans-linear arrangement of 4-aminophenol(H2O)1 is obtained containing an O-H..O hydrogen bond. In the D0 state an overlay of two spectra can be observed resulting from the trans-linear structure and a second structure which contains a N-H..O hydrogen bond. The observation of these two structures within the ion is an interesting example of a rearrangement reaction in the ionic state.

Gerhards, M.; Unterberg, C.

2001-04-01

418

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.

419

Response of ER -IR and ER -IR cells in the forebrain of female rats to mating stimuli  

E-print Network

Response of ER -IR and ER -IR cells in the forebrain of female rats to mating stimuli Be´atrice Gre -, and mating-induced Fos-immunoreactivity (Fos-ir) in neurons in which mating stimulation reliably increases, or received 15 intromissions. In the rostral medial preoptic area, Fos-ir was induced by mounts alone

Blaustein, Jeffrey D.

420

Measurement of rates of transport across erythrocyte membranes by 1H nuclear magnetic resonance spectroscopy  

NASA Astrophysics Data System (ADS)

The use of 1H NMR to monitor the transport of small molecules across the membrane of erythrocytes is evaluated. Cells are separated, as a function of time, from a suspension medium containing the small molecule of interest, and then analyzed for the small molecule by 1H NMR. 1H NMR spectra of either the intact cells or cell lysate are measured by the protein saturation pulse/Fourier transform (PSP/FT) technique. With this technique, interfering hemoglobin resonances are suppressed with a selective presaturation pulse and high-resolution spectra are obtained for small molecules. The detection limit is on the order of 0. 10 m M Membrane transport rates were measured for alanine, penicillamine, N-acetylpenicillamine, and S-methylcysteine.

Guy, Robert D.; Tahir Razi, M.; Rabenstein, Dallas L.

421

Protein-Induced Water 1H MR Frequency Shifts: Contributions from Magnetic Susceptibility and Exchange  

PubMed Central

Defining the biophysics underlying the remarkable MRI phase contrast reported in high field MRI studies of human brain would lead to more quantitative image analysis and more informed pulse sequence development. Toward this end, the dependence of water 1H resonance frequency on protein concentration was investigated using bovine serum albumin (BSA) as a model system. Two distinct mechanisms were found to underlie a water 1H resonance frequency shift: (i) a protein-concentration-induced change in bulk magnetic susceptibility, causing a shift to lower frequency, and (ii) exchange of water between chemical-shift distinct environments, i.e., free (bulk water) and protein-associated (“bound”) water, including freely exchangeable 1H sites on proteins, causing a shift to higher frequency. At 37°C the amplitude of the exchange effect is roughly half that of the susceptibility effect. PMID:19879785

Luo, Jie; He, Xiang; d'Avignon, D. Andre'; Ackerman, Joseph J. H.; Yablonskiy, Dmitriy A.

2009-01-01

422

Probing the innermost dusty structure in AGN with mid-IR and near-IR interferometers  

NASA Astrophysics Data System (ADS)

With mid-IR and near-IR long-baseline interferometers, we are now mapping the radial distribution of the dusty accreting material in AGNs at sub-pc scales. We currently focus on Type 1 AGNs, where the innermost region is unobscured and its intrinsic structure can be studied directly. As a first systematic study of Type 1s, we obtained mid-/near-IR data for small samples over ~3-4 orders of magnitudes in UV luminosity L of the central engine. Here we effectively trace the structure by observing dust grains that are radiatively heated by the central engine. Consistent with a naive expectation for such dust grains, the dust sublimation radius Rin is in fact empirically known to be scaling with L1/2 from the near-IR reverberation measurements, and this is also supported by our near-IR interferometry. Utilizing this empirical relationship, we normalize the radial extent by Rin and eliminate the simple L1/2 scaling for a direct comparison over the samples. We then find that, in the mid-IR, the overall size in units of Rin seems to become more compact in higher luminosity sources. More specifically, the mid-IR brightness distribution is rather well described by a power-law, and this power-law becomes steeper in higher luminosity objects. The near-IR flux does not seem to be a simple inward extrapolation of the mid-IR power-law component toward shorter wavelengths, but it rather comes from a little distinct brightness concentration at the inner rim region of the dust distribution. Its structure is not well constrained yet, but there is tentative evidence that this inner near-IR-emitting structure has a steeper radial distribution in jet-launching objects. All these should be scrutinized with further observations.

Kishimoto, M.; Hönig, S. F.; Antonucci, R.; Barvainis, R.; Kotani, T.; Millour, F.; Tristram, K. R. W.; Weigelt, G.

2012-07-01

423

Layered chalcogenide glass structures for IR lenses  

NASA Astrophysics Data System (ADS)

A technique for fabricating novel infrared (IR) lenses can enable a reduction in the size and weight of IR imaging optics through the use of layered glass structures. These structures can range from having a few thick glass layers, mimicking cemented doublets and triplets, to having many thin glass layers approximating graded index (GRIN) lenses. The effectiveness of these structures relies on having materials with diversity in refractive index (large ?n) and dispersion and similar thermo-viscous behavior (common glass transition temperature, ?Tg = 10°C). A library of 13 chalcogenide glasses with broad IR transmission (NIR through LWIR bands) was developed to satisfy these criteria. The lens fabrication methodology, including glass design and synthesis, sheet fabrication, preform making, lens molding and surface finishing are presented.

Gibson, Daniel; Bayya, Shyam; Sanghera, Jas; Nguyen, Vinh; Scribner, Dean; Maksimovic, Velimir; Gill, John; Yi, Allen; Deegan, John; Unger, Blair

2014-07-01

424

Thermal simulations of packaged IR LED arrays  

NASA Astrophysics Data System (ADS)

The steady-state and transient behaviors of packaged IR LED arrays have been studied via numerical simulations. The waste heat generated by LEDs must be removed through a cold plate or a cryogenic cold finger attached to the backside of the driver array. Therefore, this heat must travel across the LED array-driver interface and through the driver array. The modeling results demonstrate that the thermal resistance of these components can be significant. The steady-state temperature profiles across several configurations are used to identify the thermal bottlenecks. Transient simulations are used to quantify the rise and fall times of the IR LEDs, and the fall times can be significantly reduced by changes in the LED layout. These proposed guidelines to minimize thermal issues in LED arrays should result in better performing and more reliable IR LED arrays.

Lawler, John V.; Currano, Joseph

2008-04-01

425

Fiber Delivery of mid-IR lasers  

SciTech Connect

Fiber optics for the visible to near infrared (NIR) wavelength regimes (i.e. = 0.42 {mu}m) have proven to be extremely useful for a myriad of applications such as telecommunications, illumination, and sensors because they enable convenient, compact, and remote delivery of laser beams. Similarly, there is a need for fiber optics operating at longer wavelengths. For example, systems operating in the mid-IR regime (i.e., = 314 {mu}m) are being developed to detect trace molecular species with far-reaching applications, such as detecting explosives on surfaces, pollutants in the environment, and biomarkers in the breath of a patient. Furthermore, with the increasing availability of quantum cascade lasers (QCLs) which are semiconductor lasers that operate in the mid-IR regime additional uses are rapidly being developed. Here, we describe the development of hollow-core fibers for delivery of high-quality mid-IR laser beams across a broad spectral range.

Kriesel, J.M.; Gat, N.; Bernacki, Bruce E.; Myers, Tanya L.; Bledt, Carlos M.; Harrington, James P.

2011-08-24

426

Coordination solids derived from Cp*M(CN){sub 3}{sup {minus}} (M = Rh, Ir)  

SciTech Connect

Solutions of Rh{sub 2}(OAc){sub 4} and Et{sub 4}N[Cp*Ir(CN){sub 3}] react to afford crystals of the one-dimensional coordination solid {l_brace}Et{sub 4}N[Cp*Ir(CN){sub 3}][Rh{sub 2}(OAc){sub 4}]{r_brace}. This reaction is reversed by coordinating solvents such as MeCN. The structure of the polymer consists of helical anionic chains containing Rh{sub 2}(OAc){sub 4} units linked via two of the three CN ligands of Cp*Ir(CN){sub 3}{sup {minus}}. Use of the more Lewis acidic Rh{sub 2}(O{sub 2}CCF{sub 3}){sub 4} in place of Rh{sub 2}(OAc){sub 4} gave purple {l_brace}(Et{sub 4}N){sub 2}[Cp*Ir(CN){sub 3}]{sub 2}[Rh{sub 2}(O{sub 2}CCF{sub 3}){sub 4}]{sub 3}{r_brace}, whose insolubility is attributed to stronger Rh-NC bonds as well as the presence of cross-linking. The species {l_brace}[Cp*Rh(CN){sub 3}][Ni(en){sub n}](PF{sub 6}){r_brace} (n = 2, 3) crystallized from an aqueous solution of Et{sub 4}N[Cp*Rh(CN){sub 3}] and [Ni(en){sub 3}](PF{sub 6}){sub 2}; {l_brace}[Cp*Rh(CN){sub 3}][Ni(en){sub 2}](PF{sub 6}){r_brace} consists of helical chains based on cis-Ni(en){sub 2}{sup 2+} units. Aqueous solutions of Et{sub 4}N[Cp*Ir(CN){sub 3}] and AgNO{sub 3} afforded the colorless solid Ag[Cp*Ir(CN){sub 3}]. Recrystallization of this polymer from pyridine gave the hemipyridine adduct {l_brace}Ag[Ag(py)][Cp*Ir(CN){sub 3}]{sub 2}{r_brace}. The {sup 13}C cross-polarization magic-angle spinning NMR spectrum of the pyridine derivative reveals two distinct Cp* groups, while in the pyridine-free precursor, the Cp*'s appear equivalent. The solid-state structure of {l_brace}Ag[Ag(py)][Cp*Ir(CN){sub 3}]{sub 2}{r_brace} reveals a three-dimensional coordination polymer consisting of chains of Cp*Ir(CN){sub 3}{sup {minus}} units linked to alternating Ag{sup +} and Ag(py){sup +} units. The network structure arises by the linking of these helices through the third cyanide group on each Ir center.

Contakes, S.M.; Klausmeyer, K.K.; Rauchfuss, T.B.

2000-05-15

427

Characterization of wet aggregate stability of soils by (1) H-NMR relaxometry.  

PubMed

For the assessment of soil structural stability against hydraulic stress, wet sieving or constant head permeability tests are typically used but rather limited in their intrinsic information value. The multiple applications of several tests is the only possibility to assess important processes and mechanisms during soil aggregate breakdown, e.g. the influences of soil fragment release or differential swelling on the porous systems of soils or soil aggregate columns. Consequently, the development of new techniques for a faster and more detailed wet aggregate stability assessment is required. (1) H nuclear magnetic resonance relaxometry ((1) H-NMR relaxometry) might provide these requirements because it has already been successfully applied on soils. We evaluated the potential of (1) H-NMR relaxometry for the assessment of wet aggregate stability of soils, with more detailed information on occurring mechanisms at the same time. Therefore, we conducted single wet sieving and constant head permeability tests on untreated and 1% polyacrylic acid-treated soil aggregates of different textures and organic matter contents, subsequently measured by (1) H-NMR relaxometry after percolation. The stability of the soil aggregates were mainly depending on their organic matter contents and the type of aggregate stabilization, whereby additional effects of clay swelling on the measured wet aggregate stability were identified by the transverse relaxation time (T2 ) distributions. Regression analyses showed that only the percentage of water stable aggregates could be determined accurately from percolated soil aggregate columns by (1) H-NMR relaxometry measurements. (1) H-NMR relaxometry seems a promising technique for wet aggregate stability measurements but should be further developed for nonpercolated aggregate columns and real soil samples. Copyright © 2014 John Wiley & Sons, Ltd. PMID:25303035

Buchmann, C; Meyer, M; Schaumann, G E

2014-10-10

428

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

429

Structure and Bonding of Bi4Ir: A Difficult-to-Access Bismuth Iridide with a Unique Framework Structure.  

PubMed

Crystals of Bi4Ir, a new intermetallic compound, were obtained by the reaction of an iridium-containing intermetallic precursor with liquid bismuth. X-ray diffraction on a single crystal revealed a rhombohedral structure [R3?m, a = 2656.7(2) pm, and c = 701.6(4) pm]. Bi4Ir is not isostructural to Bi4Rh but combines motifs of the metastable superconductor Bi14Rh3 with those found in the weak topological insulator Bi14Rh3I9. The two crystallographically independent iridium sites in Bi4Ir have square-prismatic and skewed-square-antiprismatic bismuth coordination with Bi-Ir distances of 283-287 pm. By sharing common edges, the two types of [IrBi8] units constitute a complex three-dimensional network of rings and helices. The bonding in the heterometallic framework is dominated by pairwise Bi-Ir interactions. In addition, three-center bonds are found in the bismuth triangles formed by adjacent [IrBi8] polyhedra. Density functional theory based band-structure calculations suggest metallic properties. PMID:25338161

Isaeva, Anna; Ruck, Michael; Schäfer, Konrad; Rodewald, Ute Ch; Pöttgen, Rainer

2015-02-01

430

Acetylation of sugarcane bagasse using NBS as a catalyst under mild reaction conditions for the production of oil sorption-active materials.  

PubMed

Sugarcane bagasse was esterified with acetic anhydride using N-bromosuccinimide as a catalyst under mild conditions in a solvent free system. The extent of acetylation was measured by weight percent gain, which varied from 2.1% to 24.7% by changing the reaction temperature (25-130 degrees C) and duration (0.5-6.0 h). N-Bromosuccinimide was found to be a novel and highly effective catalyst for acetylation of hydroxyl groups in bagasse. At a concentration of 1% of the catalyst in acetic anhydride, a weight percent gain of 24.7% was achieved at 120 degrees C for 1 h, compared with 5.1% for the un-catalyst reaction under the same reaction condition. FT-IR and CP-MAS 13C-NMR studies produced evidence for acetylation. The thermal stability of the products decreased slightly upon chemical modification, but no significant decrease in thermal stability was observed for WPG > or = 24.7%. More importantly, the acetylation significantly increased hydrophobic properties of the bagasse. The oil sorption capacity of the acetylated bagasse obtained at 80 degrees C for 6 h, was 1.9 times higher than the commercial synthetic oil sorbents such as polypropylene fibres. Therefore, these oil sorption-active materials can be used to substitute non-biodegradable materials in oil spill cleanup. PMID:15288278

Sun, X F; Sun, R C; Sun, J X

2004-12-01

431

(1)H chemical shift differences of Prelog-Djerassi lactone derivatives: DFT and NMR conformational studies.  

PubMed

This work reports an experimental and theoretical study of the conformational preferences of several Prelog-Djerassi lactone derivatives, to elucidate the (1)H NMR chemical shift differences in the lactonic core that are associated with the relative stereochemistry of these derivatives. The boat-like conformation of explains the anomalous (1)H chemical shift between H-5a and H-5b, in which the two methyl groups (C-8 and C-9) face H-5b, leading to its higher shielding effect. PMID:25530444

Aímola, Túlio J; Lima, Dimas J P; Dias, Luiz C; Tormena, Cláudio F; Ferreira, Marco A B

2015-02-21

432

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

433

Detection of hydrogen dissolved in acrylonitrile butadiene rubber by 1H nuclear magnetic resonance  

NASA Astrophysics Data System (ADS)

Rubber materials, which are used for hydrogen gas seal, can dissolve hydrogen during exposure in high-pressure hydrogen gas. Dissolved hydrogen molecules were detected by solid state 1H NMR of the unfilled vulcanized acrylonitrile butadiene rubber. Two signals were observed at 4.5 ppm and 4.8 ppm, which were assignable to dissolved hydrogen, in the 1H NMR spectrum of NBR after being exposed 100 MPa hydrogen gas for 24 h at room temperature. These signals were shifted from that of gaseous hydrogen molecules. Assignment of the signals was confirmed by quantitative estimation of dissolved hydrogen and peak area of the signals.

Nishimura, Shin; Fujiwara, Hirotada

2012-01-01

434

Near IR spectra of symbiotic stars  

NASA Astrophysics Data System (ADS)

This overview of near-IR studies of symbiotic stars gives consideration to helium and oxygen lines in hot stars, near-IR spectra in cool stars, and nebular lines. Also examined are spectra in the range 8000-11,000 A for the following stars: RY Sct, EG And, CH Cyg, CI Cyg, AG Dra, AG Peg, RX Pup, V1016 Cyg, HM Sge, and HBV 475. It is noted that symbiotic stars simultaneously display the spectral characteristics of hot stars, cool stars (mainly of M type), nebulae, and circumstellar dust envelopes.

Andrillat, Y.

435

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

2009-04-30

436

Electronic, infrared, mass, 1H NMR spectral studies of the charge-transfer complexes of sulphonamide drugs with ?-acceptors in acetonitrile  

Microsoft Academic Search

The rapid interaction between sulphonamides (sulphamethoxazole (SMZ), sulphaguanidine (SGD), sulphaquinoxaline sodium (SQX) and sulphadimidine sodium (SDD)) as n-electron donors with the 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone (chloranilic acid, p-CLA) as ?-acceptors resulted in the formation of 1:1 charge-transfer complexes as the final products with the formula [(drug) (acceptor)]. The final products of the reactions have been isolated and characterized using FT-IR,

Eman Y. Frag; Gehad G. Mohamed

2010-01-01

437

Prediction of the 1H and 13C NMR spectra of alpha-D-glucose in water by DFT methods and MD simulations.  

PubMed

We have applied computational protocols based on DFT and molecular dynamics simulations to the prediction of the alkyl 1H and 13C chemical shifts of alpha-d-glucose in water. Computed data have been compared with accurate experimental chemical shifts obtained in our laboratory. 13C chemical shifts do not show a