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1

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

2

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 {sub 1}H{sup 2}+{sub 1}H{sup 3} using two-dimension granular molecular dynamics model  

SciTech Connect

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

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

2012-06-06

4

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

E-print Network

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

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

2011-09-10

5

Severe Infusion Reactions to Cetuximab Occur within 1 h in Patients with Metastatic Colorectal Cancer: Results of a Nationwide, Multicenter, Prospective Registry Study of 2126 Patients in Japan  

PubMed Central

Objective Infusion reactions are common adverse reactions associated with antibody preparations. However, no studies have examined the time to onset of serious infusion reactions after administering cetuximab. We aimed to investigate the timing and severity of IRs affecting Japanese patients after administration of cetuximab. Methods Study subjects were identified from a nationwide prospective registry of 2126 metastatic colorectal cancer patients scheduled to receive cetuximab. Infusion reactions were examined in 2006 patients with adequate safety data. Results Infusion reactions of any grade occurred in 114 patients (5.7%), including Grade 3–4 infusion reactions in 22 patients (1.1%). Premedications were antihistamine plus corticosteroid (88.9% of patients with infusion reactions), antihistamine alone (9.2%) or corticosteroid alone (1.1%). In 95 patients (83.3%), infusion reactions occurred after the first dose. Twenty of the 22 Grade 3–4 infusion reactions occurred within 1 h of the first dose (the timing of the infusion reaction was unknown in one patient while another infusion reaction occurred after the fourth dose). Infusion reactions resolved in 111/114 patients (97.4%) while one patient recovered with sequelae, one patient died and one patient failed to recover within the follow-up period. Thirteen patients (15.7% of patients with infusion reactions) with Grade 1–2 infusion reactions showed recurrence after readministration of cetuximab; the recurrent infusion reactions were less severe than the initial reactions. Conclusions Grade 3–4 infusion reactions occurred in 1.1% of colorectal cancer patients, and most occurred within 1 h of receiving the first dose of cetuximab. Therefore, patients should be carefully observed following cetuximab infusion, especially during the first hour after the first infusion. PMID:24771864

Yamaguchi, Kensei; Watanabe, Toshiaki; Satoh, Taroh; Ishiguro, Megumi; Izawa, Makiko; Inoshiri, Shogo; Sugihara, Kenichi; Sakata, Yuh

2014-01-01

6

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

7

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

8

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

9

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  

NASA Astrophysics Data System (ADS)

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.

Srinivasan, Krishnan; Stalin, Thambusamy

2014-09-01

10

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

11

Structure and bonding in some alkyl- and aryltin(IV) derivatives with sulfur-containing ligands studied by i.r. and 1H NMR spectroscopy  

NASA Astrophysics Data System (ADS)

A series of diorganotin(IV) and triorganotin(IV) derivatives of monothiocarboxylate and xanthate ligands, as well as several mixed-ligand diorganotin(IV) derivatives resulting from combinations of monothiocarboxylate, xanthate or N,N-dimethyldithiocarbamate ligands were prepared and studied. The structures of these complexes were discussed in the light of i.r. and 1H NMR spectra. From an exhaustive study of the i.r. spectra of the new compounds, in relation to the i.r. spectra of some other monothiocarboxylate and xanthate derivatives of transition and non-transition metals, whose structures are known, some criteria for distinguishing the bonding mode of these ligands to the central atom have emerged. On the basis of these criteria, possible structures for the new compounds are proposed and are shown to be dependent on the number and the nature of the organo-groups attached to the tin atom.

Tsipis, C. A.; Hadjikostas, C. C.; Sigalas, M. P.

12

New three-component cyclocondensation reaction: microwave-assisted one-pot synthesis of 5-unsubstituted-3,4-dihydropyrimidin-2(1 H)-ones under solvent-free conditions  

Microsoft Academic Search

Sixteen 5-unsubstituted-3,4-dihydropyrimidin-2(1H)-ones have been synthesized by microwave-assisted Biginelli reactions in a short and concise manner employing ZnI2 as a catalyst under solvent-free conditions. All products were identified by IR, NMR, elemental analysis and HRMS. The advantages of this novel protocol include the excellent yield, operational simplicity, short time and the avoidance of the use of organic solvents and expensive catalysts.

Bing Liang; Xitian Wang; Jin-Xian Wang; Zhengyin Du

2007-01-01

13

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

NASA Astrophysics Data System (ADS)

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

Huczy?ski, Adam

2013-06-01

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

FT-IR, dispersive Raman, NMR, DFT and antimicrobial activity studies on 2-(Thiophen-2-yl)-1H-benzo[d]imidazole  

NASA Astrophysics Data System (ADS)

2-(Thiophen-2-yl)-1H-benzo[d]imidazole (TBI) was synthesized under microwave conditions and was characterized by FT-IR, dispersive Raman, 1H-, 13C-, DEPT-, HETCOR-NMR spectroscopies and density functional theory (DFT) computations. The FT-IR and dispersive Raman spectra of TBI were recorded in the regions 4000-400 cm-1 and 4000-100 cm-1. The experimental vibrational spectra were interpreted with the help of normal coordinate analysis based on DFT/B3LYP/6-311++G(d,p) theory level for the more stable tautomeric form (Tautomer 1). The complete vibrational assignments were performed on the basis of the potential energy distribution (PED) of the vibrational modes, calculated with scaled quantum mechanical (SQM) method. A satisfactory consistency between the experimental and theoretical findings was obtained. The frontier molecular orbitals (FMOs), atomic charges and NMR shifts of the two stable tautomeric forms were also obtained at the same theory level without any symmetry restrictions. In addition, the title compound was screened for its antimicrobial activity and was found to be exhibit antifungal and antibacterial effects.

Ünal, Arslan; Eren, Bilge

2013-10-01

16

1H NMR of albumin in human blood plasma: drug binding and redox reactions at Cys 34  

Microsoft Academic Search

1H NMR methods are described which allow direct studies of the Cys34 binding site of albumin in intact human blood plasma in vitro. Antiarthritic gold drugs and the alcohol-aversive drug disulfiram induce a structural transition detectable via H?1 and H?2 resonances of His3 of albumin, and reactions of cystine, glutathione and captopril in plasma have also been investigated. Contrary to

John Christodoulou; Peter J. Sadler; Alan Tucker

1995-01-01

17

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

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

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

PubMed

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 (1)H and (13)C 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. PMID:21943716

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

2011-12-01

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

Solution structure of a key intermediate used in asymmetric alkylation reactions. 1H, 1H-NOESY and 6Li, 1H-HOESY studies of mixtures of a chiral lithium amide and n-butyllithium  

Microsoft Academic Search

NMR spectroscopy involving 6Li, 1H-HOESY and 6Li, 6Li-COSY studies in combination with 1H, 1H-NOESY has been used to determine the detailed structures of two complexes, are the novel mixed 1 : 1 complex between lithium-(2-methoxy-(R)-1-phenyl-ethyl)-((S)-1-phenyl-ethyl)-amide (1) and n-butyllithium, and the other the dimeric complex of 1. Both the mixed dimer between 1 and n-butyllithium and the dimeric complex of 1

Göran Hilmersson; Öjvind Davidsson

1995-01-01

22

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

23

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

24

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

PubMed Central

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

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

2014-01-01

25

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

26

Primary Amine-Catalyzed Biginelli Reaction for the Enantioselective Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones  

PubMed Central

Several chiral primary amines, mainly those derived from the cinchona alkaloids, were evaluated as the organocatalysts for the asymmetric Biginelli reaction. With the quinine-derived amine catalyst 1 and after extensive optimization of the reaction conditions, 3,4-dihydropyrimidin-2(1H)-ones were obtained in moderate to good yields and 51–78% ee from a three-component reaction of aryl and aliphatic aldehydes, urea, and acetoacetate. PMID:21188287

Ding, Derong; Zhao, Cong-Gui

2010-01-01

27

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

28

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...

29

TaBr 5-catalyzed Biginelli reaction: one-pot synthesis of 3,4-dihydropyrimidin-2-(1 H)-ones\\/thiones under solvent-free conditions  

Microsoft Academic Search

An efficient TaBr5 (5–10mol%)-catalyzed Biginelli reaction under solvent-free conditions for one-pot syntheses of 3,4-dihydropyrimidin-2-(1H)-ones (DHPMs) and their thione analogs is reported. The catalyst is stable at room temperature and employed under mild and environmentally friendly conditions.

Naseem Ahmed; Johan E. van Lier

2007-01-01

30

Application of FT-IR for in situ investigation of high temperature electrode reactions  

Microsoft Academic Search

Polarization modulated infrared reflection absorption spectroscopy (PM-IRRAS), which is one of the advanced FT-IR methods, was combined with conventional electrochemical techniques for in situ observation of high temperature electrode reactions at 773 K in oxygen partial pressure of 3×104 Pa. PM-IRRAS method can detect surface species selectively with high sensitivity at high temperatures without background measurement to cancel the infrared

Takuya Murai; Keiji Yashiro; Atsushi Kaimai; Takanori Otake; Hiroshige Matsumoto; Tatsuya Kawada; Junichiro Mizusaki

2005-01-01

31

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

32

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

33

Metal-induced B-H bond activation: reactions between half-sandwich Ir and Rh complexes with carboranylthioamide.  

PubMed

Novel half-sandwich metal (Ir, Rh) complexes constructed from carboranylthioamide ligands containing an unexpected metal-boron bond were synthesized and characterized. The strong base n-butyllithium is demonstrated to be necessary in the reaction process. PMID:25492590

Xu, Bin; Wang, Yin-Ping; Yao, Zi-Jian; Jin, Guo-Xin

2014-12-23

34

IR-spectroscopic study of the allyl + NO reaction in helium nanodroplets  

NASA Astrophysics Data System (ADS)

The IR-spectrum of the allyl-NO adduct (CH2-CH-CH2-NO) in helium nanodroplets has been recorded in the frequency region 2850-3120 cm-1. CH2-CH-CH2-NO has been investigated as a prototype of the product of radical-radical reactions at 0.37 K. The product of the reaction, 3-nitroso-1-propene, was formed via the reaction of allyl and NO within the helium droplets. For an assignment we have predicted the conformers of the CH2-CH-CH2-NO using density functional theory (DFT) with a BLYP functional and a TZVPP basis set. By comparison with the experimental spectrum we can show that all three conformers are stabilized in superfluid helium nanodroplets.

Habig, Daniel; Leicht, Daniel; Kaufmann, Matin; Schwaab, Gerhard; Havenith, Martina

2014-07-01

35

High-resolution two-proton stripping to 2p-1h 7/2- states via the 59Co(3He,n)61Cu reaction  

NASA Astrophysics Data System (ADS)

The challenge of achieving high resolution in binary reactions involving an outgoing high-energy neutron is solved by detecting the -ray decay of populated excited states in an array of escape-suppressed HPGe detectors in coincidence with fast neutrons. The selectivity of the arrangement is of the order of 1 in 1000 and is demonstrated by L = 0 two-proton stripping to 7/2- 2p-1h levels using the 59Co(3He,)61Cu reaction at E lab = 22.5 MeV. The observed relative two-proton stripping strengths are compared with large-basis shell-model calculations.

Papka, P.; Sharpey-Schafer, J. F.; Brown, B. A.; Dinoko, T. S.; Khaleel, E. A. M. A.; Lawrie, E. A.; Lawrie, J. J.; Li, K. C. W.; Majola, S. N. T.; Richter, W. A.; Shirinda, O.; Stankiewicz, M. A.; Vymers, P.; Wiedeking, M.

2014-10-01

36

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

SciTech Connect

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

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

2009-03-15

37

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

NASA Astrophysics Data System (ADS)

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

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

1996-01-01

38

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

PubMed

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

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

2013-01-01

39

Fibre optic ATR-IR spectroscopy at cryogenic temperatures: in-line reaction monitoring on organolithium compounds.  

PubMed

A reliable methodology, utilising an ATR-IR fibre probe, for in-line monitoring of low temperature reactions is presented. The application of this convenient set-up enables a fast and safe exploration of highly reactive substrates. Hence, in situ monitoring of lithiation reactions is realised and the potential to investigate sensitive intermediates is being demonstrated. PMID:22274536

Lumpi, Daniel; Wagner, Christoph; Schöpf, Matthias; Horkel, Ernst; Ramer, Georg; Lendl, Bernhard; Fröhlich, Johannes

2012-02-28

40

EPR, 1H, 31P ENDOR, and IR study of Cu(II) and Ni(II)(O,O-dimethyldithiophosphate)(N,N-dimethyldithiocarbamate) complexes  

NASA Astrophysics Data System (ADS)

Polycrystalline samples of Cu(Me 2dtp)(Me 2dtc) and Ni(Me 2dtp)(Me 2dtc) complexes are studied by means of EPR, ENDOR, and vibrational normal coordinate analysis. On the basis of EPR and ENDOR experimental results, the spin density distribution on 1H and 31P nuclei of the mixed ligand and parent copper dithiophosphate and dithiocarbamate complexes is compared. Comparison between vibrational spectra and normal coordinate analysis data on Ni(Me 2dtp)(Me 2dtc), Ni(Me 2dtp) 2 and Ni(Me 2dtc) 2 enabled the conclusion that the structure of the NiS 4 fragment in the mixed complex is retained close to that in the bis-chelate complexes.

Iliev, V.; Alexiev, V.

1995-06-01

41

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

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

42

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

43

2-Carbaborane-3-phenyl-1H-indoles – Synthesis via McMurry Reaction and COX Inhibition Activity  

PubMed Central

Cyclooxygenase-2 (COX-2) inhibitors have been in the focus of medicinal chemistry for years and many compounds exhibiting high selectivity and affinity were developed. As carbaboranes represent interesting pharmacophores as phenyl mimetics in drug development, this paper presents the synthesis of carbaboranyl derivatives of COX-2-selective 2,3-disubstituted indoles. Despite the lability of carbaboranes under reducing conditions, 2-carbaborane-3-phenyl-1H-indoles could be synthesized by McMurry cyclization of the corresponding amides. While the meta-carbaboranyl-substituted derivatives (3a-c) lacked COX inhibition activity, the ortho-carbaboranyl analog (3d) was active but showed a selectivity shift towards COX-1. PMID:23303738

Neumann, Wilma; Scholz, Matthias; Lönnecke, Peter; Crews, Brenda; Marnett, Lawrence J.; Pietzsch, Jens; Kniess, Torsten

2013-01-01

44

Quantum mechanical and spectroscopic (FT-IR, FT-Raman, 1H NMR and UV) investigations of 2-(p-nitrobenzyl) benzoxazole  

NASA Astrophysics Data System (ADS)

The optimized molecular structure, vibrational frequencies, corresponding vibrational assignments of 2-(p-nitrobenzyl)benzoxazole have been investigated experimentally and theoretically using Gaussian09 software package. Potential energy distribution of the normal modes of vibrations are done using GAR2PED program. The optimized geometrical parameters are in agreement with that of similar derivatives. 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 by using B3LYP functional with 6-31G* basis sets. The HOMO and LUMO analysis is used to determine the charge transfer with in the molecule. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis. MEP was performed by the DFT method and the infrared and Raman intensities have also been reported. Mulliken's net charges have been calculated and compared with the atomic natural charges. The calculated first hyperpolarizability of the title compound is 82.31 time that of the standard NLO material urea and hence is an attractive object for future studies of nonlinear optical properties.

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

2013-08-01

45

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

SciTech Connect

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

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

2010-11-15

46

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

47

FT-IR, FT-Raman spectra and ab initio HF and DFT calculations of 7-chloro-5-(2-chlorophenyl)-3-hydroxy-2,3-dihydro-1H-1,4-benzodiazepin-2-one.  

PubMed

The Fourier Transform infrared and Fourier Transform Raman spectra of 7-chloro-5 (2-chlorophenyl)-3-hydroxy-2,3-dihydro-1H-1,4-benzodiazepin-2-one (7C3D4B) were recorded in the regions 4000-400 and 4000-100 cm(-1), respectively. The appropriate theoretical spectrograms for the IR and Raman spectra of the title molecule were also constructed. The calculated results show that the predicted geometry can well reproduce the structural parameters. Predicted vibrational frequencies have been assigned and compared with experimental IR spectra and they supported each other. Stability of the molecule arising from hyperconjugative interactions, charge delocalization and intramolecular hydrogen bond-like weak interaction has been analyzed using natural bond orbital (NBO) analysis by using B3LYP/6-31G(d,p) method. The results show that electron density (ED) in the ?* and ?* antibonding orbitals and second-order delocalization energies E(2) confirm the occurrence of intramolecular charge transfer (ICT) within the molecule. The first order hyperpolarizability (?total) of this molecular system and related properties (?, ?, and ??) are calculated using HF/6-31G(d,p) and B3LYP/6-31G(d,p) methods based on the finite-field approach. PMID:24177883

Muthu, S; Prasath, M; Paulraj, E Isac; Balaji, R Arun

2014-01-01

48

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

PubMed Central

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

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

2014-01-01

49

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

SciTech Connect

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

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

2012-04-19

50

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

SciTech Connect

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

K Sasaki; K Kuttiyiel; D Su; R Adzic

2011-12-31

51

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

52

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

53

Spectroscopic (FT-IR, FT-Raman, 1H- and 13C-NMR), Theoretical and Microbiological Study of trans o-Coumaric Acid and Alkali Metal o-Coumarates.  

PubMed

This work is a continuation of research on a correlation between the molecular structure and electronic charge distribution of phenolic compounds and their biological activity. The influence of lithium, sodium, potassium, rubidium and cesium cations on the electronic system of trans o-coumaric (2-hydroxy-cinnamic) acid was studied. We investigated the relationship between the molecular structure of the tested compounds and their antimicrobial activity. Complementary molecular spectroscopic techniques such as infrared (FT-IR), Raman (FT-Raman), ultraviolet-visible (UV-VIS) and nuclear magnetic resonance (1H- and 13C-NMR) were applied. Structures of the molecules were optimized and their structural characteristics were calculated by the density functional theory (DFT) using the B3LYP method with 6-311++G** as a basis set. Geometric and magnetic aromaticity indices, atomic charges, dipole moments and energies were also calculated. Theoretical parameters were compared to the experimental characteristics of investigated compounds. Correlations between certain vibrational bands and some metal parameters, such as electronegativity, ionization energy, atomic and ionic radius, were found. The microbial activity of studied compounds was tested against Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa, Staphylococcus aureus, Proteus vulgaris and Candida albicans. PMID:25689641

Kowczyk-Sadowy, Ma?gorzata; ?wis?ocka, Renata; Lewandowska, Hanna; Piekut, Jolanta; Lewandowski, W?odzimierz

2015-01-01

54

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

55

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

56

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

PubMed

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 (1)H and (13)C 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. PMID:23981413

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, (13)C, (1)H) study, first order hyperpolarizability, NBO analysis, HOMO and LUMO analysis of 2-acetoxybenzoic acid by density functional methods.  

PubMed

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 4000-500cm(-1) and 4000-100cm(-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 (1)H and (13)C 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. PMID:25456668

Bhavani, K; Renuga, S; Muthu, S; Sankara Narayanan, K

2014-10-15

58

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

59

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

60

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

61

N-Substituted benzoxazolyl ureas and thioureas in Biginelli reaction promoted by trifluoromethane sulfonic acid: An efficient and convenient synthesis of substituted benzoxazolyl 3,4-dihydropyrimidine (1 H)-(thio)-ones  

Microsoft Academic Search

An efficient synthesis of 3,4-dihydropyrimidine 2 (1H)-ones and thiones (3,4-DHPMs) core was prepared by one-pot three-component Biginelli condensation and which was catalyzed by trifluoromethane sulfonic acid. The classical Bignelli reaction has been extended by the use of N-substituted benzoxazolyl semicarbazides and thiosemicarbazides and this method has the advantage of excellent yields and short reaction times.

M. Saranga Pani; M. Arjun; D. Sridhar; K. Srinivas; T. Raviprasad

2009-01-01

62

Diels-Alder reaction of 1,3-butadiene derivatives with 1-methyl-2(1H)-quinolones having an electron-withdrawing group at the 4-position.  

PubMed

Diels-Alder reactions of 1-methyl-2(1H)-quinolones having an electron-withdrawing group at the 4-position with isoprene, butadiene sulfone, and cyclohexadiene were performed to yield functionalized phenanthridones stereoselectively at atmospheric and at high pressure. Regioselectivity and stereochemistry of a methoxycarbonyl group were studied using the semi-empirical and ab initio MO methods, respectively. PMID:11456099

Fujita, R; Watanabe, K; Yoshisuji, T; Hongo, H; Matsuzaki, H

2001-07-01

63

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

64

Highly efficient Rh(I) and Ir(I) single and dual metal catalysed dihydroalkoxylation reactions of alkyne diols.  

PubMed

A highly efficient rhodium(I) and iridium(I) catalysed dihydroalkoxylation reaction of alkyne diols is employed here for the synthesis of spiroketals and a fused bicyclic ketal. The two metal catalysts show differential selectivity and efficiency for either the cyclisation of the 5-exo or 6-endo-membered rings. For the first time, a dual metal (Rh and Ir) catalyst system is effectively utilised for the formation of the 5,6-spiroketals, more efficiently than the single metal catalysts. The two different metals create a dual activation pathway to enhance the 5- and 6-membered ring closure as compared with the equivalent single catalysts. PMID:20390169

Ho, Joanne Hui Hui; Hodgson, Richard; Wagler, Jörg; Messerle, Barbara Ann

2010-05-01

65

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

NASA Astrophysics Data System (ADS)

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

Ivanov, P.; Papp, H.

2001-07-01

66

An Automated Process for a Sequential Heterocycle/Multicomponent Reaction: Multistep Continuous Flow Synthesis of 5-(Thiazol-2-yl)-3,4-Dihydropyrimidin-2(1H)-ones  

PubMed Central

The first example of a sequential heterocycle formation/multicomponent reaction using an automated continuous flow microreactor assembly is reported. Consecutive Hantzsch thiazole synthesis, deketalization, and Biginelli multicomponent reaction provides rapid and efficient access to highly functionalized, pharmacologically significant 5-(thiazol-2-yl)-3,4-dihydropyrimidin-2(1H)-ones without isolation of intermediates. These complex small molecules are generated in reaction times less than 15 min and in high yields (39–46%) over three continuous chemical steps. PMID:25237558

Pagano, Nicholas; Herath, Ananda; Cosford, Nicholas D. P.

2014-01-01

67

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

68

Kinetics study of heterogeneous reactions of ozone with erucic acid using an ATR-IR flow reactor.  

PubMed

The ozone initiated heterogeneous oxidation of erucic acid (EA) thin film was investigated using a flow system combined with attenuated total reflection infrared spectroscopy (ATR-IR) over wide ranges of ozone concentrations (0.25-60 ppm), thin film thickness (0.1-1.0 ?m), temperatures (263-298 K), and relative humidities (0-80% RH) for the first time. Pseudo-first-order rate constants, kapp, and overall reactive uptake coefficients, ?, were obtained through changes in the absorbance of C[double bond, length as m-dash]O stretching bands at 1695 cm(-1), which is assigned to the carbonyl group in carboxylic acid. Results showed that the reaction followed the Langmuir-Hinshelwood mechanism and kapp was largely dominated by surface reaction over bulk phase reaction. In addition, both the kapp and the ? values showed very strong temperature dependences (?two orders of magnitude) over the temperature range; in contrast, they only slightly increased with increasing RH values from 0-80%. According to the kapp values as a function of temperature, the activation energy for the heterogeneous reaction was estimated to be 80.6 kJ mol(-1). Our results have suggested that heterogeneous reactions between ozone and unsaturated solid surfaces likely have a substantially greater temperature dependence than liquid ones. Moreover, the hygroscopic properties of EA thin films before and after exposure to ozone were also studied by measurement of water uptake. Based on the hygroscopicity data, the insignificant RH effect on reaction kinetics was probably due to the relatively weak water uptake by the unreacted and reacted EA thin films. PMID:24457621

Leng, Chunbo; Hiltner, Joseph; Pham, Hai; Kelley, Judas; Mach, Mindy; Zhang, Yunhong; Liu, Yong

2014-03-01

69

The selective blocking of the polymerization reaction of striated muscle actin leading to a derivative suitable for crystallization. Modification of Tyr-53 by 5-diazonium-(1H)tetrazole.  

PubMed

The polymerization reaction of rabbit muscle actin was completely inhibited by reaction of one amino acid side chain per protein monomer with 5-diazonium-(1H)[14C]tetrazole. A tryptic peptide fingerprint showed a single peptide labeled by the reagent. The peptide was isolated and the labeled amino acid identified by amino acid analysis as Tyr-53. This side chain is not accessible to the reagent in F-actin. The modification is compared to similar inhibitions by other reagents. PMID:1278154

Bender, N; Fasold, H; Kenmoku, A; Middelhoff, G; Volk, K E

1976-04-15

70

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

71

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

72

Yttria-Zirconia–Based Lewis Acid Catalysis of the Biginelli Reaction: An Efficient One-Pot Synthesis of 3,4-Dihydropyrimidin-2-(1H)-ones  

Microsoft Academic Search

Yttria-zirconia–based Lewis acid efficiently catalyzes the three-component cyclocondensation reaction of aldehyde, ?-keto ester, and urea or thiourea in refluxing acetonitrile to produce the corresponding dihydropyrimidones in high yields.

S. Ramalingam; Pradeep Kumar

2009-01-01

73

Thermal 1,3-trityl migrations in Diels-Alder domino reactions of 1-trityl-4-vinyl-1H-imidazoles.  

PubMed

Under thermal conditions, tritylimidazoles have been shown to undergo sterically driven N-->N trityl migrations, in disagreement with previously published reports. These migrations are a key step in several highly diastereoselective domino reaction sequences (Diels-Alder, [1,3]-H shift, [1,3]-trityl migration and Diels-Alder, [1,3]-H shift, [1,3]-trityl migration, Michael reaction) leading to architecturally complex molecules. PMID:20527990

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

2010-07-01

74

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

75

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

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

76

Solvent?Free Approach to 3,4?Dihydropyrimidin?2(1H)?(thio)ones: Biginelli Reaction Catalyzed by a Wells–Dawson Reusable Heteropolyacid  

Microsoft Academic Search

The Biginelli reaction is performed in an efficient, simple, solvent?free procedure, using a small amount of H6P2W18O62 · 24H2O, a reusable heteropolyacid catalyst with Wells–Dawson structure. Both aromatic and aliphatic aldehydes, and different ??dicarbonyl compounds and urea or thiourea, were used as starting materials. Seventeen examples of dihydropyrimidinones and dihydropyrimidinethiones were prepared by heating the reactants either in refluxing acetonitrile or in

Gustavo P. Romanelli; Angel G. Sathicq; Juan C. Autino; Graciela Baronetti; Horacio J. Thomas

2007-01-01

77

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

SciTech Connect

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

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

1988-02-23

78

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

79

Molecular structure, FT-IR, vibrational assignments, HOMO-LUMO analysis and molecular docking study of 1-[5-(4-Bromophenyl)-3-(4-fluorophenyl)-4,5-dihydro-1H-pyrazol-1-yl]ethanone  

NASA Astrophysics Data System (ADS)

The optimized molecular structure, vibrational frequencies, corresponding vibrational assignments of 1-[5-(4-bromophenyl)-3-(4-fluorophenyl)-4,5-dihydro-1H-pyrazol-1-yl]ethanone have been investigated experimentally and theoretically using Gaussian09 software package. The title compound was optimized using the HF/6-31G(d) (6D, 7F), B3LYP/6-31G (6D, 7F) and B3LYP/6-311++G(d,p) (5D, 7F) calculations. The B3LYP/6-311++G(d,p) (5D, 7F) results and in agreement with experimental infrared bands. 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. Molecular electrostatic potential was also performed. From the MEP it is evident that the negative charge covers the Cdbnd O group and the positive region is over the rings. First hyperpolarizability is calculated in order to find its role in nonlinear optics. Molecular docking studies suggest that 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; Fun, H. K.

2015-02-01

80

Molecular structure, FT-IR, vibrational assignments, HOMO-LUMO analysis and molecular docking study of 1-[5-(4-Bromophenyl)-3-(4-fluorophenyl)-4,5-dihydro-1H-pyrazol-1-yl]ethanone.  

PubMed

The optimized molecular structure, vibrational frequencies, corresponding vibrational assignments of 1-[5-(4-bromophenyl)-3-(4-fluorophenyl)-4,5-dihydro-1H-pyrazol-1-yl]ethanone have been investigated experimentally and theoretically using Gaussian09 software package. The title compound was optimized using the HF/6-31G(d) (6D, 7F), B3LYP/6-31G (6D, 7F) and B3LYP/6-311++G(d,p) (5D, 7F) calculations. The B3LYP/6-311++G(d,p) (5D, 7F) results and in agreement with experimental infrared bands. 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. Molecular electrostatic potential was also performed. From the MEP it is evident that the negative charge covers the CO group and the positive region is over the rings. First hyperpolarizability is calculated in order to find its role in nonlinear optics. Molecular docking studies suggest that the compound might exhibit inhibitory activity against TPII and may act as anti-neoplastic agent. PMID:25448948

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

2015-02-01

81

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.  

PubMed

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. PMID:25448949

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

82

Spectroscopic (FT-IR, 1H, 13C NMR, UV), DOS and orbital overlap population analysis of copper complex of (E)-4-(2-(4-nitrophenyl) diazenyl)-N, N bis ((pyridin-2-yl) methyl) benzamine by density functional theory  

NASA Astrophysics Data System (ADS)

The geometric parameters, chemical shifts, FTIR, NMR and orbital overlap population along with DOS (density of states) to know different kinds of interactions for binding of copper atom with (E)-4-(2-(4-nitrophenyl) diazenyl)-N, N bis ((pyridin-2-yl) methyl) benzamine to form its copper complex has been reported by DFT methods. The theoretically predicted values for structural parameters are in agreement with the experimentally reported values. NMR chemical shifts calculated using B3LYP/DFT/GIAO level of theory gives information about binding of copper atom with three nitrogen atoms namely N (3, 8 and 11). Orbital overlap population analysis using DFT/B3LYP/SDD level of theory is used to study the kind of interactions involved in binding of copper with the three nitrogen atoms. DOS studies are done to know about the contribution of alpha, beta electrons to the valence and conduction band. IR spectroscopy investigations gave the absorption bands for the formation of title compound. Electronic spectrum along with HOMO-LUMO energies of the title compound has been investigated using Time-dependent (TD-DFT) approach.

Diwaker

2015-02-01

83

Visible-light-induced, Ir-catalyzed reactions of N-methyl-N-((trimethylsilyl)methyl)aniline with cyclic ?,?-unsaturated carbonyl compounds  

PubMed Central

Summary N-Methyl-N-((trimethylsilyl)methyl)aniline was employed as reagent in visible-light-induced, iridium-catalyzed addition reactions to cyclic ?,?-unsaturated carbonyl compounds. Typical reaction conditions included the use of one equivalent of the reaction substrate, 1.5 equivalents of the aniline and 2.5 mol % (in MeOH) or 1.0 mol % (in CH2Cl2) [Ir(ppy)2(dtbbpy)]BF4 as the catalyst. Two major reaction products were obtained in combined yields of 30–67%. One product resulted from aminomethyl radical addition, the other product was a tricyclic compound, which is likely formed by attack of the intermediately formed ?-carbonyl radical at the phenyl ring. For five-membered ?,?-unsaturated lactone and lactam substrates, the latter products were the only products isolated. For the six-membered lactones and lactams and for cyclopentenone the simple addition products prevailed. PMID:24778745

Lenhart, Dominik

2014-01-01

84

Visible-light-induced, Ir-catalyzed reactions of N-methyl-N-((trimethylsilyl)methyl)aniline with cyclic ?,?-unsaturated carbonyl compounds.  

PubMed

N-Methyl-N-((trimethylsilyl)methyl)aniline was employed as reagent in visible-light-induced, iridium-catalyzed addition reactions to cyclic ?,?-unsaturated carbonyl compounds. Typical reaction conditions included the use of one equivalent of the reaction substrate, 1.5 equivalents of the aniline and 2.5 mol % (in MeOH) or 1.0 mol % (in CH2Cl2) [Ir(ppy)2(dtbbpy)]BF4 as the catalyst. Two major reaction products were obtained in combined yields of 30-67%. One product resulted from aminomethyl radical addition, the other product was a tricyclic compound, which is likely formed by attack of the intermediately formed ?-carbonyl radical at the phenyl ring. For five-membered ?,?-unsaturated lactone and lactam substrates, the latter products were the only products isolated. For the six-membered lactones and lactams and for cyclopentenone the simple addition products prevailed. PMID:24778745

Lenhart, Dominik; Bach, Thorsten

2014-01-01

85

On the formation of the J/sup. pi. / = 1/2/sup -5/Li state in the /sup 6/Li(/sup 3/He,. cap alpha cap alpha. )/sup 1/H reaction  

SciTech Connect

The analysis of the ..cap alpha cap alpha.. bidimensional spectrum for theta/sub 1/ = 47/sup 0/, phi/sub 1/ = 0/sup 0/ and theta/sub 2/ = 88/sup 0/, phi/sub 2/ = 180/sup 0/ of the /sup 6/Li(/sup 3/He,..cap alpha cap alpha..)/sup 1/H reaction at E(/sup 3/He) = 1.65 MeV is a suitable way of calculating the excitation energy and width of the first excited state in the /sup 5/Li nucleus. The deduced values are E/sub x/ = 5.8 +- 0.5 MeV and T = 5.2 +- 0.5 MeV.

Fazio, G.; Femino-grave-accent, S.; Giardina, G.; Italiano, A.; Mezzanares, F.; Palamara, R.

1987-01-01

86

The primary acceptor quinone Q A in reaction centers of Rhodobacter sphaeroides R26 is hydrogen bonded to the N ?(1) -H of His M219. An electron spin echo study of Q A-•  

NASA Astrophysics Data System (ADS)

An electron spin echo envelope modulation (ESEEM) study is performed on the reduced primary electron-accepting ubiquinone-10 (Q A-•) in Zn-substituted reaction centers of the photosynthetic bacterium Rhodobacter sphaeroides R26. The ESEEM spectra showed hyperfine and quadrupolar couplings of Q A-• to nitrogens in the protein matrix. Simulation of the spectra revealed the following 14N coupling parameters: hyperfine interaction: Aiso = 1.85 MHz, T11 = 0.32, ? = 0 0, ? = 45 0; nuclear quadrupole interaction: e2qQ/ h = 1.52 MHz, ? = 0.82. Comparison of the quadrupole values with data in the literature shows that Q A-• is coupled to the N ?(1) -H group of the M219 heterocycle, most probably through a hydrogen bond with the 4-C carbonyl group of the quinone.

Bosch, M. K.; Gast, P.; Hoff, A. J.; Spoyalov, A. P.; Tsvetkov, Yu. D.

1995-06-01

87

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

88

Ab initio calculation for potential energy surfaces relevant to the microscopic reaction pathways for Mg(3s3p1P1)+H2?MgH(2?+)+H  

NASA Astrophysics Data System (ADS)

Two ab initio methods have been employed to calculate the dynamical potential energy surfaces (PES's) for the excited (1B2 or 1A') and the ground (1A1 or 1A') states in the Mg(3s3p1P1)-H2 reaction. The obtained PES's information reveals that the production of MgH in the 2?+ state, as Mg(1P1) approaches H2 in a bent configuration, involves a nonadiabatic transition. The MgH2 intermediate around the surface crossing then elicits two distinct reaction pathways. In the first one, the bent intermediate, affected by a strong anisotropy of the interaction potential, decomposes via a linear HMgH geometry. The resulting MgH is anticipated to populate in the quantum states of rotational and vibrational excitation. In contrast, the second pathway produces MgH in the low rotational and vibrational states, as a result of the intermediate decomposition along the stretching coordinate of the Mg-H elongation. These two tracks may account for the previous experimental findings for the MgH distribution, which the impulsive model has failed to comprehend. By far, different interpretations have been proposed especially for the low-N MgH product. The supply of a detailed PES's information in this work helps to clarify the ambiguity. It is also conducive to an interpretation of the isotope and temperature effects on the product rotational distribution.

Ou, Yaw-Ren; Liu, Dean-Kuo; Lin, King-Chuen

1998-01-01

89

Measurement of the 187Re({\\alpha},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 {\\ga...

Scholz, P; 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

2015-01-01

90

Quantum dynamics of the reaction H((2)S) + HeH(+)(X(1)?(+)) ? H2(+)(X(2)?g(+)) + He((1)S) from cold to hyperthermal energies: time-dependent wavepacket study and comparison with time-independent calculations.  

PubMed

We present the adiabatic quantum dynamics of the proton-transfer reaction H((2)S) + HeH(+)(X(1)?(+)) ? H2(+)(X(2)?g(+)) + He((1)S) on the HeH2(+) X?(2)?(+) RMRCI6 (M = 6) PES of C. N. Ramachandran et al. ( Chem. Phys. Lett. 2009, 469, 26). We consider the HeH(+) molecule in the ground vibrational–rotational state and obtain initial-state-resolved reaction probabilities and the ground-state cross section ?0 and rate constant k0 by propagating time-dependent, coupled-channel, real wavepackets (RWPs) and performing a flux analysis. Three different wavepackets are propagated to describe the wide range of energies explored, from cold (0.0001 meV) to hyperthermal (1000 meV) collision energies, and in a temperature range from 0.01 to 2000 K. We compare our time-dependent results with the time-independent ones by D. De Fazio and S. Bovino et al., where De Fazio carried out benchmark coupled-channel calculations whereas Bovino et al. employed the negative imaginary potential and the centrifugal-sudden approximations. The RWP cross section is in good agreement with that by De Fazio, except at the lowest collision energies below ?0.01 meV, where the former is larger than the latter. However, neither the RWP and De Fazio results possess the huge resonance in probability and cross section at 0.01 meV, found by Bovino et al., who also obtained a too low ?0 at high energies. Therefore, the RWP and De Fazio rate constants compare quite well, whereas that by Bovino et al. is in general lower. PMID:24738984

Gamallo, Pablo; Akpinar, Sinan; Defazio, Paolo; Petrongolo, Carlo

2014-08-21

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

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

93

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

94

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

95

Synthesis, crystal structure and biological activity of 1-(1 H-benzoimidazol-2-yl)-ethanone thiosemicarbazone and its cobalt complex  

Microsoft Academic Search

1-(1H-Benzoimidazol-2-yl)-ethanone thiosemicarbazone (H2L) (1) was obtained by the condensation reaction of 2-acetylbenzimidazole, thiosemicarbazide and acetic acid in ethanol. The novel cobalt(III) complex [Co(L)(HL)] 2 was prepared by the direct reaction of CoCl2·6H2O with the ligand H2L. The reaction products were characterized by elemental analysis, thermogravimetric analysis (TGA), FT-IR and mass spectrometry for H2L, and magnetic measurement for the Co(III) complex.

Mehmet Poyraz; Musa Sari; Fatih Demirci; Muberra Kosar; Seref Demirayak; Orhan Büyükgüngör

2008-01-01

96

Frontispiece: using surface segregation to design stable ru-ir oxides for the oxygen evolution reaction in acidic environments.  

PubMed

Surface Analysis N.?M. Markovic et?al. describe in their Communication on page?14016?ff. how the activity of bimetallic oxide materials for the oxygen evolution reaction can be tuned through surface segregation of the elements into nanosegregated domains. PMID:25491260

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

97

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

PubMed

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

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

2014-07-21

98

DFT calculations of XPS/NEXAFS and IR spectra to elucidate the reaction products of acetonitrile with Si(0 0 1)-2 × 1  

NASA Astrophysics Data System (ADS)

NEXAFS data [S. Rangan et al., Phys. Rev. B 71 (2005) 165319] and FTIR data [M.P. Schwartz, R.J. Hamers, Surf. Sci. 601 (2007) 945] apparently do not converge in the identification of the reaction products of acetonitrile (CH 3CN) with Si(0 0 1)-2 × 1 at room temperature. Using DFT calculations of core-excited/core-ionized spectra and of IR vibrational frequencies and intensities, we show the consistency of the body of experimental data. Three species are present on the surface in equivalent amounts, a C dbnd N moiety, a pendent C tbnd N and a C dbnd C dbnd N ketenimine submitted to a strong twist imposed by the Si bond directionality. More generally, the paper shows the usefulness of spectroscopic data simulations in the elucidation of complex surface chemistry problems.

Carniato, S.; Rochet, F.; Gallet, J.-J.; Bournel, F.; Dufour, G.; Mathieu, C.; Rangan, S.

2007-12-01

99

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

PubMed

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

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

2012-02-21

100

Design, synthesis and biological activity of new strobilurin derivatives with a 1H-pyrazol-5-oxy side chain.  

PubMed

A series of new strobilurin derivatives with a substituted pyrazole side chain (5 and 6) were designed and synthesized. The new derivatives were synthesized from substituted phenones as starting material via esterification, cyclization and condensation reactions. All compounds were identified by 1H NMR and IR spectral and elemental analyses. Preliminary biological evaluation showed that some of the compounds had good fungicidal activity against cucumber downy mildew (CDM) and wheat powdery mildew (WPM) at 6.25 and 1.56 mg L(-1), respectively. Some of the compounds showed insecticidal activity against armyworm (AW), green peach aphid (GPA) and culex mosquitoes at 600 mg L(-1). PMID:19831032

Li, Miao; Liu, Chang-Ling; Yang, Ji-Chun; Li, Lin; Li, Zhi-Nian; Zhang, Hong; Li, Zheng-Ming

2009-09-01

101

Access to functionalized 3H-pyrrolo[2,3-c]quinolin-4(5H)-ones and thieno[2,3-c]quinolin-4(5H)-ones via domino reaction of 4-alkynyl-3-bromoquinolin-2(1H)-ones.  

PubMed

We describe two efficient protocols for the straightforward synthesis of 3H-pyrrolo[2,3-c]quinolin-4(5H)-one and thieno[2,3-c]quinolin-4(5H)-one derivatives from readily available 4-alkynyl-3-bromoquinolin-2(1H)-one as precursor. The efficient synthesis of highly functionalized 3H-pyrrolo[2,3-c]quinolin-4(5H)-ones has been achieved via a palladium-catalyzed domino reaction of 4-alkynyl-3-bromoquinolin-2(1H)-ones with amines. Thieno[2,3-c]quinolin-4(5H)-one derivatives were also conveniently synthesized via sequential nucleophilic aromatic substitution/5-endo-dig cyclization between 4-alkynyl-3-bromoquinolin-2(1H)-ones and sodium sulfide with good functional tolerance under mild conditions. PMID:25244431

Wang, Zhiyong; Xue, Lijun; He, Yiyi; Weng, Licong; Fang, Ling

2014-10-17

102

Living cationic polymerization of 1H,1H,2H,2H perfluorooctyl vinyl ether  

Microsoft Academic Search

Cationic polymerization of 1H,1H,2H,2H perfluorooctyl vinyl ether (CH2=CH-O-C2H4-C6F13), initiated by the HI\\/ZnI2 system in 1,1,2 trichloro trifluoro ethane at-30°C, leads to living polyvinyl ethers bearing a fluoroalkyl group. Results indicate that the polymerization is indeed free from chain transfer and termination reactions and that polyethers of controlled molecular weight and a narrow molecular weight distribution can be made available.

Christian Vandooren; Robert Jérôme; Philippe Teysslé

1994-01-01

103

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

E-print Network

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

Nakagawa, I.

104

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

105

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

106

Reactions of Rh and Ir-bis(iminophosphoranyl)methanide compounds with electrophiles; a trapped cation-anion complex in the oxidative addition of iodine to a d 8 metal centre and X-ray crystal structure of IrI{CH(PPh 2?N?C 6H 4?CH 3-4) 2}(COD)]I, containing two fused four-membered metallacycles  

Microsoft Academic Search

Reaction of square planar M{CH(PPh2?N?C6H4?CH3-4)2(COD)] (1a: M?Rh; 1b: M?Ir), in which the bis-iminophosphoranylmethanide ligand is bidentate N,C-coordinated, with I2, MeI and MeOSO2CF3 yields products resulting from metal or ligand (N atom) centered reactivity. Complexes 1a and 1b react with MeI and MeOSO2CF3 to yield mainly cationic N-methyl or N,N?-dimethyl derivatives. The reaction of b1 with I2 results in the selective

Pieter Imhoff; Jan H. Gülpen; Kees Vrieze; Wilberth J. J. Smeets; Anthony L. Spek; Cornelis J. Elsevier

1995-01-01

107

Labile Cu(I) catalyst/spectator Cu(II) species in copper-catalyzed C-C coupling reaction: operando IR, in situ XANES/EXAFS evidence and kinetic investigations.  

PubMed

Insights toward the Cu-catalyzed C-C coupling reaction were investigated through operando IR and in situ X-ray absorption near-edge structure/extended X-ray absorption fine structure. It was found that the Cu(I) complex formed from the reaction of CuI with ?-diketone nucleophile was liable under the cross-coupling conditions, which is usually considered as active catalytic species. This labile Cu(I) complex could rapidly disproportionate to the spectator Cu(II) and Cu(0) species under the reaction conditions, which was an off-cycle process. In this copper-catalyzed C-C coupling reaction, ?-diketone might act both as the substrate and the ligand. PMID:23214954

He, Chuan; Zhang, Guanghui; Ke, Jie; Zhang, Heng; Miller, Jeffrey T; Kropf, Arthur J; Lei, Aiwen

2013-01-01

108

Selenium-containing heterocycles: synthesis and pharmacological activities of some new 4-methylquinoline-2(1H) selenone derivatives.  

PubMed

Several selenolo[2,3-b]quinolines and pyrimido[4',5':4,5]selenolo[2,3-b]quinolines were prepared by annulations via reaction of NaSeH with 2-chloro-3-cyano-4-methylquinoline 1 followed by reactions with aromatic aldehydes, cycloalkanones, and acetic anhydride. Spectroscopic (IR, 1H-NMR, and MS) properties of the synthesized compounds are reported. Some selected compounds 5a, 7b, 7c, 8b-d, 9a, 11b, and 11d were investigated for their anti-inflammatory and analgesic activities; in addition, the most active compounds were tested for their ulcerogenicity and acute toxicity. Moreover, some of the test compounds 7c, 9a, 11b, and 11d were screened for their antibacterial and antifungal activities. PMID:18275038

Abdel-Hafez, Shams H; Hussein, Mostafa A

2008-04-01

109

Picoliter 1H NMR Spectroscopy  

NASA Astrophysics Data System (ADS)

In this study, a 267-?m-diameter solenoid transceiver is used to acquire localized 1H NMR spectra and the measured signal-to-noise ratio (SNR) at 500 MHz is shown to be within 20-30% of theoretical limits formulated by considering only its resistive losses. This is illustrated using a 100-?m-diameter globule of triacylglycerols (˜900 mM) that may be an oocyte precursor in young Xenopus laevis frogs and a water sample containing choline at a concentration often found in live mammalian cells (˜33 mM). In chemical shift imaging (CSI) experiments performed using a few thousand total scans, the choline methyl line is shown to have an acceptable SNR in resolved volume elements containing only 50 pL of sample, and localized spectra are resolved from just 5 pL in the Xenopus globule. These findings demonstrate the feasibility of performing 1H NMR on picoliter-scale sample volumes in biological cells and tissues and illustrate how the achieved SNR in spectroscopic images can be predicted with reasonable accuracy at microscopic spatial resolutions.

Minard, Kevin R.; Wind, Robert A.

2002-02-01

110

Organo-niobate Ionic Liquids: Synthesis, Characterization and Application as Acid Catalyst in Pechmann Reactions  

PubMed Central

The combinations of 1-butyl-3-methylimidazolium chloride with NbCl5 yielded ionic mixtures with different melting point temperatures and acidity depending on the niobium molar fraction. The mixtures were characterized by thermal (DSC) and spectroscopic (FT-IR and 1H NMR) analysis. The Pechmann reactions of different phenols with ethylacetoacetate, producing coumarins, was used as model to evaluate the catalytic behavior of these mixtures as acid Lewis catalyst. These reactions were carried out using acidic mixtures of 60 mol%.

Soares, Valerio C. D.; Alves, Melquizedeque B.; Souza, Ernesto R.; Pinto, Ivana O.; Rubim, Joel C.; Andrade, Carlos Kleber Z.; Suarez, Paulo A. Z.

2007-01-01

111

Towards high-level theoretical studies of large biodiesel molecules: an ONIOM [QCISD(T)/CBS:DFT] study of hydrogen abstraction reactions of C(n)H(2n+1)COOC(m)H(2m+1) + H.  

PubMed

Recent interest in biodiesel combustion urges the need for the theoretical chemical kinetics of large alkyl ester molecules. This is, however, computationally challenging for prevalent high-level electronic structure theory based methods. The hydrogen abstraction reactions of alky esters CnH2n+1COOCmH2m+1 (n = 1-5, 9, 15; m = 1, 2) by a hydrogen radical were investigated by a computational technique based on a two-layer ONIOM method, employing a QCISD(T)/CBS method for the high layer and a DFT method for the low layer. The calculated energy barriers and heats of reaction, using the ONIOM method with a minimum of the required chemically active portion, are in very good agreement with those obtained using the widely accepted high-level QCISD(T)/CBS theory because the computational errors were less than 0.1 kcal mol(-1) for all the tested cases. The ONIOM[QCISD(T)/CBS:DFT] method provides a computationally accurate and affordable approach to the high-level theoretical chemical kinetics of large biodiesel molecules. PMID:25382675

Zhang, Lidong; Zhang, Peng

2015-01-01

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

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

114

Computational study of the reaction of C6F6 with [IrMe(PEt3)3]: identification of a phosphine-assisted C-F activation pathway via a metallophosphorane intermediate.  

PubMed

Density functional theory calculations have been used to model the reaction of C6F6 with [IrMe(PEt3)3], which proceeds with both C-F and P-C bond activation to yield trans-[Ir(C6F5)(PEt3)2(PEt2F)], C2H4, and CH4 (Blum, O.; Frolow, F.; Milstein, D. J. Chem. Soc., Chem. Commun. 1991, 258). Using a model species, trans-[IrMe(PH3)2(PH2Et)], a low-energy mechanism involving nucleophilic attack of the electron-rich Ir metal center at C6F6 with displacement of fluoride has been identified. A novel feature of this process is the capture of fluoride by a phosphine ligand to generate a metallophosphorane intermediate [Ir(C6F5)(Me)(PH3)2(PH2EtF)]. These events occur in a single step via a 4-centered transition state, in a process that we have termed "phosphine-assisted C-F activation". Alternative mechanisms based on C-F activation via concerted oxidative addition or electron-transfer processes proved less favorable. From the metallophosphorane intermediate the formation of the final products can be accounted for by facile ethyl group transfer from phosphorus to iridium followed by beta-H elimination of ethene and reductive elimination of methane. The interpretation of phosphine-assisted C-F activation in terms of nucleophilic attack is supported by the reduced activation barriers computed with the more electron-rich model reactant trans-[IrMe(PMe3)2(PMe2Et)] and the higher barriers found with lesser fluorinated arenes. Reactivity patterns for a range of fluoroarenes indicate the dominance of the presence of ortho-F substituents in promoting phosphine-assisted C-F activation, and an analysis of the charge distribution and transition state geometries indicates that this process is controlled by the strength of the Ir-aryl bond that is being formed. PMID:18950169

Erhardt, Stefan; Macgregor, Stuart A

2008-11-19

115

Structural studies of 1-phenyl-2,3-dimethyl-5-oxo-1,2-dihydro-1H-pyrazol-4-ammonium 2[(2-carboxyphenyl) disulfanyl]benzoate  

NASA Astrophysics Data System (ADS)

Reaction of 4-aminoantipyrine with 2-mercaptobenzoic acid afforded a proton transfer derivative, 1-phenyl-2,3-dimethyl-5-oxo-1,2-dihydro-1H-pyrazol-4-ammonium 2[(2-carboxyphenyl) disulfanyl]benzoate, (HAAP+?HTBA-), via the oxidation of 2-mercaptobenzoic acid into 2,2'-dithiobis(benzoic acid). The compound has been characterized on the basis of elemental analysis, IR, 1H and 13C NMR and mass spectral data. The infrared spectrum suggests the existence of an ion-pair compound, which is further established by the single crystal X-ray analysis to be an extended 1D supramolecular chain network extending along 'b' cell direction. The compound shows good thermal stability.

Fazil, Shiji; Ravindran, Reena; Sarau Devi, A.; Bijili, B. K.

2012-08-01

116

Synthesis of 1H-indazoles and 1H-pyrazoles via FeBr3/O2 mediated intramolecular C-H amination.  

PubMed

A new synthesis of substituted 1H-indazoles and 1H-pyrazoles from arylhydrazones via FeBr(3)/O(2) mediated C-H activation/C-N bond formation reactions is reported. The corresponding 1,3-diaryl-substituted indazoles and trisubstituted pyrazoles were obtained in moderate to excellent yields under mild conditions. PMID:23297649

Zhang, Tianshui; Bao, Weiliang

2013-02-01

117

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

118

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

119

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

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

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

2014-08-21

122

IR Spectra of Isocyanic Acid (HNCO) and its Reaction Product with Ammonia: Possible Identification of the 4.6 and 6.8 Micron Absorption Features of Several Protostellar Objects  

NASA Astrophysics Data System (ADS)

Strong absorption features are found at 4.6 microns (2170 cm-1) and 6.8 microns (1470 cm-1) in the spectra of several protostellar objects (e.g. W33A, NGC 7538 IRS9, RAFGL 7009S). Ices with similar features may have been present in the early solar system. Realistic candidates responsible for the 6.8 micron band include CH3OH, and/or ions such as CO3=, HCO3-, and NH4+. The 4.6 micron feature is due to the absorption of the cyanate ion (OCN-). We have synthesized and obtained the infrared spectrum of pure, solid HNCO and measured its intrinsic band strength. We have also investigated the IR spectrum of HNCO covered with a layer of H2O and NH3 at low temperatures ( 10K). During warm-up to 100K, an acid-base reaction occurs and new peaks develop around 1470 cm-1 and 2170 cm-1 which are due to NH4+ and OCN- ions, respectively. Irradiation of solid HNCO shows evidence of OCN- formation at low temperatures. The conditions under which NH4OCN converts into urea ((NH2)2CO) will be discussed. Ammonium cyanate is a good candidate for the source of the 4.6 and 6.8 micron interstellar features and may also exist in cometary ices.

Lowenthal, M. S.; Khanna, R. K.; Moore, M. H.

2000-10-01

123

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

124

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

125

ORIGINAL PAPER Dinuclear Ir(III) Complex with an Unusual g1  

E-print Network

Abstract The unique dinuclear Ir(III) complex (Cp*IrCl) (l-H)[l-(g1 :g3 -C6H6S)](IrCp*) (1) has been synthesized and characterized by NMR spectroscopy (1 H and 13 C), elemental analysis, and single crystal X ). The NMR data indicate the solution state structure is consistent with the solid state structure. Keywords

Jones, William D.

126

Time-Resolved Quantitative Measurement of OH HO2 and CH2O in Fuel Oxidation Reactions by High Resolution IR Absorption Spectroscopy.  

SciTech Connect

Combined with a Herriott-type multi-pass slow flow reactor, high-resolution differential direct absorption spectroscopy has been used to probe, in situ and quantitatively, hydroxyl (OH), hydroperoxy (HO 2 ) and formaldehyde (CH 2 O) molecules in fuel oxidation reactions in the reactor, with a time resolution of about 1 micro-second. While OH and CH 2 O are probed in the mid-infrared (MIR) region near 2870nm and 3574nm respectively, HO 2 can be probed in both regions: near-infrared (NIR) at 1509nm and MIR at 2870nm. Typical sensitivities are on the order of 10 10 - 10 11 molecule cm -3 for OH at 2870nm, 10 11 molecule cm -3 for HO 2 at 1509nm, and 10 11 molecule cm -3 for CH 2 O at 3574nm. Measurements of multiple important intermediates (OH and HO 2 ) and product (CH 2 O) facilitate to understand and further validate chemical mechanisms of fuel oxidation chemistry.

Huang, Haifeng; Rotavera, Brandon; Taatjes, Craig A.

2014-08-01

127

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

PubMed

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

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

2014-01-01

128

Preparation of 5-substituted 1H-tetrazoles from nitriles in water.  

PubMed

The addition of sodium azide to nitriles to give 1H-tetrazoles is shown to proceed readily in water with zinc salts as catalysts. The scope of the reaction is quite broad; a variety of aromatic nitriles, activated and unactivated alkyl nitriles, substituted vinyl nitriles, thiocyanates, and cyanamides have all been shown to be viable substrates for this reaction. PMID:11722189

Demko, Z P; Sharpless, K B

2001-11-30

129

Novel N-substituted-5-phenyl-1 H-pyrazole-4-ethyl carboxylates as potential NLO materials  

Microsoft Academic Search

In the present investigation we have synthesized a novel series of N-substituted-5-phenyl-1H-pyrazole-4-ethyl carboxylates, which are characterized by 1H NMR, UV–Vis and FT-IR spectroscopy methods. The optical nonlinearity of the compounds in chloroform solution has been studied at 532nm using 5ns laser pulses, employing the open-aperture z-scan technique. It is found that compound 3c having carboxylic acid group and ester substituent

B. Chandrakantha; Arun M. Isloor; Kishore Sridharan; Reji Philip; Prakash Shetty; Mahesh Padaki

130

1H NMR Relaxation in Urea  

E-print Network

Duer. Solid state 13 C CP MAS NMR study of molecular motionsKey Words: NMR; 1 H NMR; 13 C CP/MAS; 15 N CP/MAS; spin-NMR techniques are used to study such systems, the standard cross- polarization/magic angle spinning (CP/

Taylor, Robert E; Bacher, Alfred D; Dybowski, C.

2007-01-01

131

Synthesis and structural characterization of 1,2-bis((1 H-pyrrol-2-yl)methylene)hydrazine and its Cu(II) complex  

NASA Astrophysics Data System (ADS)

The hydrogen-bonding potential and complexation behavior with copper(II) of a multidentate Schiff-base ligand, 1,2-bis((1 H-pyrrol-2-yl)methylene)hydrazine (H 2L) was studied. Crystallization of H 2L from an aqueous methanol solution resulted in the formation of an adduct H 2L·H 2O, which features a two-dimensional (2D) supramolecular hydrogen-bonded network, as evidenced by X-ray structural analysis. The reaction of H 2L with copper(II) salt in a CH 2Cl 2sbnd MeOH solution formed a dinuclear double-stranded helicate, Cu 2( L) 2 ( 1) in high yield, which was characterized by microanalysis, IR spectra, and single-crystal X-ray crystallographic analysis. UV-vis titration experiments confirmed the spontaneous formation of a 1:1 metal-ligand complex in solution.

Zhang, Guoqi; Yang, Lanying; Ma, Jinshi; Yang, Guoqiang

2011-12-01

132

Electronic, infrared, mass, 1H NMR spectral studies of the charge-transfer complexes of sulphonamide drugs with ?-acceptors in acetonitrile  

NASA Astrophysics Data System (ADS)

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, 1H NMR, mass spectroscopy and elemental analyses as well as photometric measurements and thermogravimetric analysis (TG). The stoichiometry and apparent formation constants of the complexes formed were determined by applying the conventional spectrophotometric molar ratio method.

Frag, Eman Y.; Mohamed, Gehad G.

2010-08-01

133

Atmospheric chemistry of CF3CF2CHO: absorption cross sections in the UV and IR regions, photolysis at 308 nm, and gas-phase reaction with OH radicals (T = 263-358 K).  

PubMed

The relative importance in the atmosphere of UV photolysis of perfluoropropionaldehyde, CF3CF2CHO, and reaction with hydroxyl (OH) radicals has been investigated in this work. First, the forbidden n ? ?* transition of the carbonyl chromophore was characterized between 230 and 380 nm as a function of temperature (269–298 K) and UV absorption cross sections, ??, were determined in those ranges. In addition, IR absorption cross sections were determined between 4000 and 500 cm–1. Pulsed laser photolysis (PLP) of CF3CF2CHO coupled to Fourier transform infrared (FTIR) was employed to determine the overall photolysis quantum yield, ??, at 308 nm and 298 K. ??=308 nm was pressure dependent, ranging from (0.94 ± 0.14) at 75 Torr to (0.30 ± 0.01) at 760 Torr. This dependence is characterized by the Stern–Volmer parameters ?0?=308 nm = (1.19 ± 0.34) and KSV = (1.22 ± 0.52) × 10(–19) cm3 molecule–1. End products of the photodissociation of CF3CF2CHO were measured and quantified by FTIR spectroscopy. Furthermore, the rate coefficients for the OH + CF3CF2CHO reaction, k1, were determined as a function of temperature (T = 263–358 K) by PLP-LIF. At room temperature the rate coefficient is k1(T = 298 K) = (5.57 ± 0.07) × 10(–13) cm3 molecule–1 s–1, whereas the temperature dependence is described by k1(T) = (2.56 ± 0.32) × 10(–12) exp{?(458 ± 36)/T} cm3 molecule–1 s–1. On the basis of our results, photolysis of CF3CF2CHO in the actinic region could be an important removal process for CF3CF2CHO in the atmosphere. The formation of the primary products in the UV photolysis of CF3CF2CHO is also discussed. PMID:24299449

Antiñolo, María; Jiménez, Elena; González, Sergio; Albaladejo, José

2014-01-01

134

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...

135

Garso ir judesio sinchronizacija.  

E-print Network

??Šiame darbe apžvelgiami garso ir animacijos apdorojimo metodai. Pateikiami metod? privalumai ir tr?kumai. Aptariama Adobe Flash technologija, jos panaudojimas grafikoje. Supažindinama su objektinio programavimo kalba… (more)

Dauskurdis,; Darius

2011-01-01

136

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

PubMed Central

Trichloroacetic acid was found to be a convenient catalyst for the synthesis of 3,4-dihydropyrimidin-2-(1H)-ones and their corresponding 2(1H)-thiones through a one-pot three-component reaction of aldehydes, alkyl acetoacetate, and urea or thiourea at 70°C under solvent-free conditions. PMID:24052844

Karimi-Jaberi, Zahed; Moaddeli, Mohammad Sadegh

2012-01-01

137

1H-NMR microscopy of tablets.  

PubMed

A 1H-nuclear magnetic resonance (NMR) microscopy method was utilized for the first time to determine the porosity distribution of physically intact tablets. The main advantage of this newly developed method was that porosity cross sections through whole tablets or specific locations could be obtained without mechanically destroying the tested tablet. This was achieved by filling tablet cavities with silicone oil under vacuum. The amount of silicone oil locally within the tablet was then determined by 1H-NMR microscopy, revealing the inverse inner structure. To reduce the measuring time, a paramagnetic gadolinium complex was added to the silicone oil. The cross sectional signals produced by 1H-NMR microscopy through the tablet were transformed into a color image by a specially designed computer graphic program. To improve the signal-noise ratio an algorithm of 3D-filtering was introduced. The maximal spatial resolution achieved with this method was about 95 microns for a cube's edge length corresponding to some 380,000 positions in a 9-mm-diameter compression-coated tablet. Uneven porosity distributions within tablets, cracks, or cavities could be visualized with this newly developed method. Different compaction mechanisms were observed with plastic- or brittle-type tablets. The different states of densification during compaction of powders could be detected. The integrity of compression coatings was determined to be dependent on the pressure load and the location of the core within the coat. PMID:7616364

Nebgen, G; Gross, D; Lehmann, V; Müller, F

1995-03-01

138

(1) H NMR analysis of O-methyl-inositol isomers: a joint experimental and theoretical study.  

PubMed

Density functional theory (DFT) calculations of (1) H NMR chemical shifts for l-quebrachitol isomers were performed using the B3LYP functional employing the 6-31G(d,p) and 6-311?+?G(2d,p) basis sets. The effect of the solvent on the B3LYP-calculated NMR spectrum was accounted for using the polarizable continuum model. Comparison is made with experimental (1) H NMR spectroscopic data, which shed light on the average uncertainty present in DFT calculations of chemical shifts and showed that the best match between experimental and theoretical B3LYP (1) H NMR profiles is a good strategy to assign the molecular structure present in the sample handled in the experimental measurements. Among four plausible O-methyl-inositol isomers, the l-quebrachitol 2a structure was unambiguously assigned based only on the comparative analysis of experimental and theoretical (1) H NMR chemical shift data. The B3LYP infrared (IR) spectrum was also calculated for the four isomers and compared with the experimental data, with analysis of the theoretical IR profiles corroborating assignment of the 2a structure. Therefore, it is confirmed in this study that a combined experimental/DFT spectroscopic investigation is a powerful tool in structural/conformational analysis studies. PMID:22865668

De Almeida, Mauro V; Couri, Mara Rubia C; De Assis, João Vitor; Anconi, Cleber P A; Dos Santos, Hélio F; De Almeida, Wagner B

2012-09-01

139

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

140

IR-background database  

Microsoft Academic Search

The Swedish Defence Research Agency (FOI) has recently performed systematic measurements in order to establish an IR-background database. It will be used for a wide range of applications and provide a basis for the modeling of IR-background properties of Swedish terrain. Experimental data like this is also necessary for the validation of methods and programs for synthetic IR-scene simulation. The

Claes Nelsson; Paer Nilsson; Roland Lindell; Emma Bernhardsson

2001-01-01

141

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.

142

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.

143

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.

144

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

PubMed

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

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

2014-07-01

145

Synchrotron IR spectromicroscopy: chemistry of living cells.  

PubMed

Advanced analytical capabilities of synchrotron IR spectromicroscopy meet the demands of modern biological research for studying molecular reactions in individual living cells. (To listen to a podcast about this article, please go to the Analytical Chemistry multimedia page at pubs.acs.org/page/ancham/audio/index.html.). PMID:20839782

Holman, Hoi-Ying N; Bechtel, Hans A; Hao, Zhao; Martin, Michael C

2010-11-01

146

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

147

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

PubMed Central

The reaction of CoCl2·6H2O with m-BDTH2 (1,3-benzeneditetrazol-5-yl) leads to [Co(C8H6N8)2(H2O)2(CH3CN)2]Cl2 (1). Both tetrazolic groups remain protonated existing in a 1H tautomeric form. A trifurcated chlorine atom and stacking interactions assemble compound 1 into a three-dimensional network. PMID:20631832

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

2010-01-01

148

A Thermally-Reliable, Low-Resistivity Cu(Ir) and Cu(IrN) Alloy Films for Barrierless Cu Metallization  

NASA Astrophysics Data System (ADS)

In this study, copper (Cu) alloy films developed by reactive co-sputtering of Cu with iridium (Ir) in an Ar/N2 atmosphere to render Cu(Ir) and Cu(IrNx) seed layers on barrierless Si substrates are found to exhibit great thermal stability, low resistivity, and a good adhesion feature. The Cu(Ir) and Cu(IrNx) films are annealed at 650 and 730 °C for 1 h, displaying good thermal stability with low leakage current for the latter and low resistivity values of 4.32 and 2.67 µ? cm, respectively; no copper silicide formation occurs at the Cu-Si interface. The IrNx's thermal stability and low resistivity reveal that the Cu(IrNx) is a good candidate for advanced barrierless metallization in forming a new type of interconnect for electronic components, such as capacitors.

Lin, Chon-Hsin

2012-05-01

149

Synthesis, spectral characterisation of 2-(5-methyl-1H-benzimidazol-2-yl)-4-bromo/nitro-phenols and their complexes with zinc(II) ion, and solvent effect on complexation.  

PubMed

2-(5-Methyl-1H-benzimidazol-2-yl)-4-bromo/nitro-phenols (HLBr and HLNO2) and their Zn(II) complexes with ZnX2 (X = Cl, I, NO3) were synthesized and characterized by elemental analysis, molar conductivity, IR, 1H and 13C NMR spectra. The OH proton appears near the NH protons in the 1H NMR spectra of the ligands because of the strong intramolecular hydrogen bonding between the OH hydrogen and the C=N nitrogen atoms. The complexation is investigated in ethanol and isopropanol and it is observed that isopropanol is a better solvent than ethanol for the complex forming. HLBr gives harder complexation reaction with Zn(II) according to HLNO2 because of the stronger intramolecular hydrogen bonding in HLBr, and the both ligands react easier with Zn(NO3)2 than ZnCl2 and ZnI2. The Zn(II) complexes of HLBr have 1:1 M:L ratio and ionic character, however, HLNO2 give a non-ionic complex that has 1:2 M:L ratio. In the complexes the phenolic hydrogen is eliminated and a chelate structure is formed. PMID:15978864

Tavman, Aydin

2006-02-01

150

Quantitation of metabolites by 1H NMR.  

PubMed

In this report we describe the three factors that need to be measured when quantitating an edited resonance relative to an internal standard using a surface coil. These factors are necessary by virtue of the water, fat suppressing, and localization schemes used in studing a 1H metabolite. First, use of semi-selective pulses requires amplitude correction of the edited and reference resonances. Second, use of a single surface coil results in different sensitive volumes for different resonances due to the inhomogeneous B1 and therefore require separate acquisition of the resonances. Third, editing pulses alter the sensitive volumes and this correction must be made internally by applying the same editing pulse to the reference resonance. A rationalization of this correction is given in terms of rotation operators. We apply these corrections to quantitate edited lactate relative to total creatine in a MnCl2-doped phantom and find 91% rather than 145% of known concentration. In human skeletal muscle in vivo after exhaustive exercise, we measured the lactate after exercise and found it to be 27.2 mM in two experiments, in reasonable agreement with literature values for the given exercise protocol. PMID:1943661

Pan, J W; Hetherington, H P; Hamm, J R; Shulman, R G

1991-07-01

151

Praseodymium Methanesulfonate Catalyzed One?Pot Synthesis of 3,4?Dihydropyrimidin?2?(1H)?ones  

Microsoft Academic Search

A series of 3,4?dihydropyrimidin?2?(1H)?ones compounds was synthesized efficiently by a one?pot cyclocondensation of an aldehyde, 1,3?dicarbonyl compound, and urea in absolute ethanol under refluxing temperature using praseodymium methanesulfonate as catalyst. After the reaction, the catalyst can be easily recovered and reused several times without distinct decrease in reaction yields.

Min Wang; Zhiguo Song; Hong Gong; Heng Jiang

2007-01-01

152

The Mechanism of the Ritter Reaction in Combination with Wagner-Meerwein Rearrangements. A Cooperative Learning Experience  

NASA Astrophysics Data System (ADS)

Based on previously described experiments on the Ritter reaction between tert-butyl alcohol and benzonitrile in the presence of concentrated sulfuric acid and on the analysis of three computed hypothetical pathways, also previously described, Ritter reactions using the remaining three isomeric butyl alcohols in which Wagner-Meerwein rearrangements can take place are performed. From this information students are able to propose a mechanism for the Ritter reaction compatible with the experimental evidence they themselves obtained. The reactions are run simultaneously by groups of students under very simple experimental conditions, the reference compounds are prepared and characterized using melting point determination and IR and 1H NMR spectroscopy, and the reaction products are identified by TLC. Since the students have to share samples and information, they have a fruitful, cooperative learning experience.

Colombo, María I.; Bohn, María L.; Rúveda, Edmundo A.

2002-04-01

153

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

154

{sup 1}H NMR spectroscopy: Approaches for carbonaceous solids  

SciTech Connect

This chapter provides an introduction and overview of the {sup 1}H CRAMPS (combined rotation and multiple-pulse spectroscopy) technique as applied to carbonaceous solids, primarily coal. The basic nature and characteristics of the CRAMPS experiment are explained. Its applications to coal, oil shale, kerogen, humic acid, and fulvic acid are described. Some of the technical characteristics and requirements of the {sup 1}H CRAMPS experiment are outlined. Directions for future {sup 1}H CRAMPS applications to carbonaceous solids are discussed.

Maciel, G.E.; Bronnimann, C.E.; Ridenour, C.F. [Colorado State Univ., Fort Collins, CO (United States)

1993-12-31

155

IR gain monitor  

NASA Astrophysics Data System (ADS)

The gain of the IR channel of WFC3 will be measured using a series of internal flat fields. Using knowledge gained from ground testing and previous cycles, we propose to collect flat field ramps which will be used to create photon transfer curves and give a measure of the gain. This continues the strategy of last cycle's gain monitor, in proposal 13080.

Hilbert, Bryan

2013-10-01

156

ir. Tim Brys Information  

E-print Network

ir. Tim Brys Contact Information Artificial Intelligence Lab +32 (0) 477 186 209 Vrije Universiteit Brussel timbrys@vub.ac.be Pleinlaan 2 http://ai.vub.ac.be/members/tim-brys 1050 Brussels, Belgium Last Chapters [1] Tim Brys, Yann-Micha¨el De Hauwere, Ann Now´e and Peter Vrancx (2012). Local coordination

Steels, Luc

157

Regioselective dehydrogenation of 3,4-dihydropyrimidin-2(1 H)-ones mediated by ceric ammonium nitrate  

Microsoft Academic Search

Ceric ammonium nitrate (CAN) has been explored for the regioselective oxidation of 3,4-dihydropyrimidin-2(1H)-ones (DHPMs). Interestingly, we obtained ethyl 2,4-dioxo-6-phenyl-tetrahydropyrimidin-5-carboxylates as the major products during the oxidation of DHPMs by CAN\\/AcOH at 80°C. The reaction afforded a mixture of products while employing CAN in organic solvents without additives. However, the regioselective dehydrogenated product, ethyl 6-methyl-4-aryl(alkyl)-pyrimidin-2(1H)-one-5-carboxylate was obtained by performing the reaction

P. Shanmugam; P. T. Perumal

2006-01-01

158

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

PubMed

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

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

2011-09-01

159

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

160

Identification and functional assessment of endothelial P1H12.  

PubMed

Monoclonal antibody P1H12 recognizes circulating endothelial cells and endothelia of all sizes of blood vessels. To identify the protein recognized by P1H12, we expressed a cDNA library in CHO cells and sequenced the cDNA from positive cells. The P1H12 sequence was identical, except at several bases, to that reported for melanoma cell surface antigen MUC18/CD146. Aggregation assays demonstrated that CD146 mediates Ca(++)-independent homotypic endothelial cell adhesion. P1H12 mAb abrogated interactions between human microvascular endothelial cells (HMVECs) but not between human umbilical vein endothelial cells (HUVECs). P1H12 mAb abrogated P1H12-positive (CHO(P1H12))-association with HMVECs or HUVECs. CD146 distribution is sparser on HUVECs than on HMVECs. These data imply that HMVECs and HUVECs express the CD146 binding partner but that CD146 is functional (or at sufficient density) only on HMVECs. HMVEC monolayers treated with soluble P1H12 mAb showed increased permeability to albumin, with accompanying changes in actin, paxillin, FAK, and caveolin distribution and changes in tyrosine phosphorylation of FAK. Stimulation with P1H12 mAb led to redistribution of NF-kappa B to the nucleus. P1H12 mAb bound to beads inhibited closure of wounded endothelial monolayers. CD146 thus joins VE-cadherin and PECAM-1 as a molecule that mediates homotypic endothelial cell adhesion. CD146 has both structural functions and signaling functions important for endothelial monolayer integrity. PMID:11709656

Solovey, A N; Gui, L; Chang, L; Enenstein, J; Browne, P V; Hebbel, R P

2001-11-01

161

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

162

Cryostat attachment for IR spectrometers  

Microsoft Academic Search

UDC 535.853 Devices for controlling the temperature are employed in IR spectroscopy in order to obtain spectra of materials at low and medium temperatures. The geometry of the optical system of such devices is traditional and corresponds to recording IR transmission spectra. In many cases the information obtained from IR transmission spectra is inadequate. For example, for strongly absorbing materials

A. N. Ternovoi; B. Z. Belashev

1989-01-01

163

Permeable membrane/mass spectrometric measurement of solvent /sup 1/H//sup 2/H, /sup 12/C//sup 13/C, and /sup 16/O//sup 18/O kinetic isotope effects associated with alpha-chymotrypsin deacylation: evidence for reaction mechanism plasticity  

SciTech Connect

We have measured, by permeable membrane/mass spectrometry, the /sup 16/O//sup 18/O, /sup 12/C//sup 13/C, and solvent H/sup 2/O/D/sup 2/O kinetic isotope effects (kie) associated with acyl-alpha-chymotrypsin hydrolysis and transesterification. The hydrolysis of alpha-chymotrypsinyl 2-furoate has a /sup 12/C//sup 13/C kie of approximately 1.06. Transesterification of the same acyl enzyme shows /sup 16/O//sup 18/O, /sup 12/C//sup 13/C, and solvent H/sup 2/O/D/sup 2/O kinetic isotope effects of 1.015 (0.003), 1.01-1.02, and 2.226 (0.007), respectively. From the temperature independence of the /sup 16/O//sup 18/O transesterification kinetic isotope effect and kinetic data reported elsewhere, we conclude that there are two active forms of acylchymotrypsin. We also propose that formation of the tetrahedral intermediate is the rate-limiting step in both hydrolysis and transesterification and that the position of the transition state in the transesterification is closer to the starting enzyme ester while that for the hydrolytic reaction is closer to the tetrahedral intermediate. These results are discussed in terms of reaction mechanism plasticity.

Mishra, A.K.; Klapper, M.H.

1986-11-18

164

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

165

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

PubMed Central

(6-(cyclohexylamino)-1,3-dimethyl-5(2-pyridyl)furo[2,3-d]pyrimidine-2,4(1H,3H)-dione) abbreviated as CDP was synthesized and characterized. Ti(IV), Zn(II), Fe(III), and Pd(II) metal complexes of this ligand are prepared by the reaction of salts of Ti(IV), Zn(II), Fe(III), and Pd(II) with CDP in acetonitrile. Characterization of the ligand and its complexes was made by microanalyses, FT-IR, 1H NMR, 13C NMR, and UV-Visible spectroscopy. All complexes were characterized by several techniques using elemental analysis (C, H, N), FT-IR, electronic spectra, and molar conductance measurements. The elemental analysis data suggest the stoichiometry to be 1:1 [M:L] ratio formation. The molar conductance measurements reveal the presence of 1:1 electrolytic nature complexes. These new complexes showed excellent antitumor activity against two kinds of cancer cells that are K562 (human chronic myeloid leukemia) cells and Jurkat (human T lymphocyte carcinoma) cells. PMID:19190768

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

2008-01-01

166

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

Swaddle, John

167

Synthesis of novel 1H-pyrrolizine-5-carboxamides and their antimicrobial properties.  

PubMed

A variety of N-aryl-7-cyano-2,3-dihydro-1H-pyrrolizine-5-carboxamides 6, 8-11 were synthesized through the reaction of the 2-amino derivatives 3 with acid chlorides, aromatic and aliphatic aldehydes. In addition, 3 could directly obtained through the reaction of 2-pyrrolidinylidenepropanedinitrile (1) with chloroacetanilides 2a,b. However, reaction of 1 with-chloropropionanilide 2c gave the open-chain compound 5. The antimicrobial properties of the newly prepared compounds were screened against a variety of Gram positive, Gram-negative bacteria and yeast. Some of the prepared compounds (8a, 8c and 9a) show moderate activity against the tested Gram-positive bacteria (Staphylococcus aureus and/or Coagulase negative Staphylococcus). In addition, other compounds (6a, 9d and 9e) exhibit slight (weak) activity against Coagulase negative Staphylococcus. PMID:12918225

Barsoum, F F; Nawar, N N

2003-05-01

168

One-pot synthesis, FT-IR, NMR and density functional method (B3LYP) studies on 2-(cyclohexylamino)-2-oxo-1-(pyridin-2-yl)ethyl benzoate  

Microsoft Academic Search

2-(Cyclohexylamino)-2-oxo-1-(pyridin-2-yl)ethyl benzoate has been synthesized and characterized by elemental analysis, FT-IR, 1H NMR and 13C NMR. Geometrical structures, vibrational frequencies, 1H and 13C chemical shift values, molecular electrostatic potential maps and several thermodynamic parameters of title compound in the ground state have been calculated by using the density functional method with 6-31G(d) basis set. The IR spectrum of title compound

E. Fereyduni; E. Vessally; E. Yaaghubi; N. Sundaraganesan

2011-01-01

169

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

170

IR Dark Monitor  

NASA Astrophysics Data System (ADS)

Analysis of ground and on-orbit observations has shown that dark current is most effectively removed from external science images when using a composite dark calibration image created from a number of individual dark calibration images taken with the same sample sequence, exposure time, and aperture. Collection of dark calibration frames for all sample-sequence/aperture size combinations used by Cycle 21 IR-channel external observations is essential. They will be used to monitor variations in the dark current signal and will provide the input images necessary to generate timely, high-quality composite dark calibration frames which will be delivered to the calibration database system {CDBS} on an as-needed basis. In addition, some darks will also be used to monitor bad pixels and the long-term stability of the dark current, as well as trends in the zeroth read level, and bad pixels {hot, unstable, or dead}.

Dulude, Michael

2013-10-01

171

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

PubMed

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

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

2005-06-13

172

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

173

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

Microsoft Academic Search

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

Sirirat Chancharunee; Pilaiwan Pinhom; Manat Pohmakotr; Patrick Perlmutter

2009-01-01

174

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

175

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

176

Automated Multistep Continuous Flow Synthesis of 2-(1H-Indol-3-yl)thiazole Derivatives  

PubMed Central

The multistep continuous flow assembly of 2-(1H-indol-3-yl)thiazoles using a Syrris AFRICA® synthesis station is reported. Sequential Hantzsch thiazole synthesis, deketalization and Fischer indole synthesis provides rapid and efficient access to highly functionalized, pharmacologically significant 2-(1H-indol-3-yl)thiazoles. These complex, drug-like small molecules are generated in reaction times of less than 15 min and in high yields (38%–82% over three chemical steps without isolation of intermediates). PMID:24634547

Pagano, Nicholas; Heil, Marintha L.

2014-01-01

177

Zn(OTf) 2 -catalyzed three component, one-pot cyclocondensation reaction of some new octahydroquinazolinone derivatives and access their bio-potential  

Microsoft Academic Search

An efficient synthesis of some new octahydroquinazolinone derivatives 4a–x by the cyclocondensation reaction of corresponding 2-thi(oxo)-1,2-dihydroquinoline-3-carbaldehyde 1a–e, 1,3-dicarbonyl compounds 2a–b, and substituted urea 3a–c using zinc triflate as a catalyst in refluxing ethanol in high yield is described. The structures of new compounds have been\\u000a characterized on the basis of elemental analysis, FT- IR, 1H NMR, 13C NMR, and mass

Pushpak M. Shah; Manish P. Patel

178

Methods For Determining Reactive Intermediates By FT-IR Spectroscopy  

NASA Astrophysics Data System (ADS)

The ability to actually examine a reaction mechanism is limited by the various intermediates along a reaction coordinate. Detailed information concerning a mechanism is critical for the thorough understanding of the chemistry and physics involved. Matrix isolation affords the opportunity to slow down or freeze out molecular or atomic species which would be unobservable at or near room temperature. In combination with FT-IR, matrix isolation techniques can be used to obtain high quality spectral data of various intermediates.

Rosenthal, R. J.; Walder, F. T.

1985-12-01

179

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

180

Ir-Surface enriched porous Ir-Co oxide hierarchical architecture for high performance water oxidation in acidic media.  

PubMed

The large-scale application of acidic water electrolysis as a viable energy storage technology has been hindered by the high demand of precious metal oxides at anode to catalyze the oxygen evolution reaction (OER). We report an Ir-Co binary oxide electrocatalyst for OER fabricated by a multistep process of selective leaching of Co from Co-rich composite oxides prepared through thermal decomposition. The stepwise leaching of the Co component from the composites leads to the formation of macro- and mesoscale voids walled by a cross-linked nanoporous network of rod- and wedge-like building units of Ir-Co binary oxide with a rutile phase structure and an Ir-enriched surface. In comparison, Ir-Co binary oxide with similar composition prepared by direct thermal decomposition method exhibits a loose nanoparticle aggregation morphology with a Co-enriched surface. The cross-linked porous Ir-Co binary oxide from selective leaching is about 3-fold more active for the OER than that from direct thermal decomposition. Compared with pure IrO2 from thermal decomposition, the Co-leached binary oxide is ca. two times more active and is much more durable during continuous oxygen evolution under a constant potential of 1.6 V, thus showing a possibility of reducing the demand of the expensive and scarce Ir in OER electrocatalyst for acidic water splitting. PMID:24984084

Hu, Wei; Zhong, Huawei; Liang, Wei; Chen, Shengli

2014-08-13

181

Design, Synthesis and Anti-Tobacco Mosaic Virus (TMV) Activity of 5-Chloro-N-(4-cyano-1-aryl-1H-pyrazol-5-yl)-1-aryl-3-methyl-1H-pyrazole-4-carboxamide Derivatives.  

PubMed

A series of novel pyrazole amide derivatives 3a-3p which take TMV PC protein as the target has been designed and synthesized by the reactions of 5-chloro-1-aryl-3-methyl-1H-pyrazole-4-carboxylic acids with 5-amino-1-aryl-1H-pyrazole-4-carbonitriles. All the compounds were characterized by 1H-NMR, mass spectroscopy and elemental analysis. Preliminary bioassays indicated that all the compounds acted against the tobacco mosaic virus (TMV) with different in vivo and in vitro modes at 500 ?g/mL and were found to possess promising activity. Especially, compound 3p showed the most potent biological activity against tobacco mosaic virus (TMV) compared to ningnanmycin, and a molecular docking study was performed and the binding model revealed that the pyrazole amide moiety was tightly embedded in the binding sites of TMV PC (PDB code: 2OM3). PMID:25574822

Xiao, Jin-Jing; Liao, Min; Chu, Ming-Jie; Ren, Zi-Li; Zhang, Xin; Lv, Xian-Hai; Cao, Hai-Qun

2014-01-01

182

? decay of the ?h11/2 isomer in Ir164  

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

183

The IR Theory Discussion List  

NSDL National Science Digital Library

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

1996-01-01

184

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

PubMed Central

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

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

2014-01-01

185

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

186

1H NMR analysis of sporopollenin from Typha Angustifolia  

Microsoft Academic Search

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

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

1999-01-01

187

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

188

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

189

Reduction of C,N-chelated chloroborane: straightforward formation of the unprecedented 1H-2,1-benzazaborolyl potassium salt.  

PubMed

Reduction of C,N-chelated chloroborane [2-(CH=NtBu)C6H4]BPhCl () with the potassium metal afforded (3,3')-bis(1-Ph-2-tBu-1H-2,1-benzazaborole) (2). Compound 2 is formed via C-C reductive coupling reaction. Subsequent reduction of 2 with two equivalents of the potassium metal produced orange crystals of 1Ph-2tBu-1H-2,1-benzazaborolyl (Bab) potassium salt K(THF)(Bab) (3). Compound 3 is able to react with simple electrophiles (MeI or Me3SiCl) resulting in the formation of substituted 1H-2,1-benzazaboroles. PMID:24788675

Hejda, Martin; Jambor, Roman; R?ži?ka, Aleš; Ly?ka, Antonín; Dostál, Libor

2014-06-28

190

Transient UV pump-IR probe investigation of heterocyclic ring-opening dynamics in the solution phase: the role played by n?* states in the photoinduced reactions of thiophenone and furanone.  

PubMed

The heterocyclic ring-opening dynamics of thiophenone and furanone dissolved in CH3CN have been probed by ultrafast transient infrared spectroscopy. Following irradiation at 267 nm (thiophenone) or 225 nm (furanone), prompt (? < 1 ps) ring-opening is confirmed by the appearance of a characteristic antisymmetric ketene stretching feature around 2150 cm(-1). The ring-opened product molecules are formed highly vibrationally excited, and cool subsequently on a ?6.7 ps timescale. By monitoring the recovery of the parent (S0) bleach, it is found that ?60% of the initially photoexcited thiophenone molecules reform the parent molecule, in stark contrast with the case in furanone where there is less than 10% parent bleach recovery. Complementary ab initio calculations of potential energy cuts along the S-C([double bond, length as m-dash]O) and O-C([double bond, length as m-dash]O) ring-opening coordinate reveals insights into the reaction mechanism, and the important role played by dissociative (n/?)?* states in the UV-induced photochemistry of such heterocyclic systems. PMID:25175813

Murdock, Daniel; Harris, Stephanie J; Luke, Joel; Grubb, Michael P; Orr-Ewing, Andrew J; Ashfold, Michael N R

2014-10-21

191

Brønsted Acidic Ionic Liquid–Catalyzed One-Pot Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones and Thiones Under Solvent-Free Conditions  

Microsoft Academic Search

An efficient and convenient procedure for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones and thiones by condensation of ethylacetoacetate, aldehydes, and urea or thiourea in the presence of methylimidazolium hydrogensulfate is described. Aromatic and aliphatic aldehydes reacted easily to afford the corresponding 3,4-dihydropyrimidin-2(1H)-ones and thiones under solvent-free conditions. The use of nontoxic and inexpensive materials, straightforward and clean workup, short reaction times, and

Abdol R. Hajipour; Leila Khazdooz; Amin Zarei

2011-01-01

192

Visual and Near-IR Photometry of Nova Del 2013  

NASA Astrophysics Data System (ADS)

We report Visual and Near-IR photometry of Nova Del 2013 taken at the University of Minnesota's O'Brien Observatory (Marine-on-St-Croix, Minnesota, USA). VRIJHKLM photometry were obtained on two successive nights using an AsSi bolometer. Vega (alpha Lyrae) was used as the standard star. Our photometry show: August 16.2 UT: V = 4.8 +/- 0.1, R = 5.4 +/- 0.1, I = 5.2 +/- 0.1, J = 4.4 +/- 0.1, H = 4.3 +/- 0.1, K = 4.3 +/- 0.1, L = 4.5 +/- 0.2.

Gehrz, R. D.; Dykhoff, D. A.; Shenoy, D. P.

2013-08-01

193

IR susceptibility of naval ships using ShipIR\\/NTCS  

Microsoft Academic Search

Methods of analysing the signature and susceptibility of naval platforms to infrared detection are described. An unclassified ShipIR destroyer model is used to illustrate the primary sources of infrared signature and detection: the exhaust system, solar-heating, and operating climate. The basic detection algorithm used by the Naval Threat Countermeasure Simulator (NTCS) component of ShipIR is described and used to analyse

David A. Vaitekunas

2010-01-01

194

1H-NMR and Hyperpolarized 13C-NMR Assays of Pyruvate-Lactate Exhange: a comparative study  

PubMed Central

Pyruvate-lactate exchange is mediated by the enzyme lactate dehydrogenase (LDH) and is central to the altered energy metabolism in cancer cells. Measurement of exchange kinetics using hyperpolarized 13C NMR has provided a biomarker of response to novel therapeutics. In this study we investigated an alternative in vitro 1H assay, using [3-13C]pyruvate, and compared the measured kinetics with a hyperpolarized 13C-NMR assay, using [1-13C]pyruvate, under the same conditions in human colorectal carcinoma SW1222 cells. The apparent forward reaction rate constants (kPL) derived from the two assays showed no significant difference, and both assays had similar reproducibility (kPL = 0.506 ± 0.054 and kPL = 0.441 ± 0.090 nmol/s/106 cells, (mean ± standard deviation, n = 3); 1H, 13C assays respectively). The apparent backward reaction rate constant (kLP) could only be measured with good reproducibility using the 1H-NMR assay (kLP = 0.376 ± 0.091 nmol/s/106 cells, (mean ± standard deviation, n = 3)). The 1H-NMR assay has adequate sensitivity to measure real-time pyruvate-lactate exchange kinetics in vitro, offering a complementary and accessible assay of apparent LDH activity. PMID:23712817

Orton, Matthew R.; Tardif, Nicolas; Parkes, Harold G.; Robinson, Simon P.; Leach, Martin O.; Chung, Yuen-Li; Eykyn, Thomas R.

2015-01-01

195

Synthesis, spectral characterisation of 2-(5-methyl-1 H-benzimidazol-2-yl)-4-bromo\\/nitro-phenols and their complexes with zinc(II) ion, and solvent effect on complexation  

Microsoft Academic Search

2-(5-Methyl-1H-benzimidazol-2-yl)-4-bromo\\/nitro-phenols (HLBr and HLNO2) and their Zn(II) complexes with ZnX2 (X=Cl, I, NO3) were synthesized and characterized by elemental analysis, molar conductivity, IR, 1H and 13C NMR spectra. The OH proton appears near the NH protons in the 1H NMR spectra of the ligands because of the strong intramolecular hydrogen bonding between the OH hydrogen and the CN nitrogen atoms.

Ayd?n Tavman

2006-01-01

196

Oxazoline and imidazoline functionalization of a C60 dimer via the reaction of C60HBn and aromatic nitriles with a bifunctional hydroxide.  

PubMed

Oxazoline and imidazoline functionalization of a singly bonded C60 dimer is achieved via a one-pot reaction of C60HBn with OH(-) and aromatic nitriles, where the OH(-) not only functions as a Brønsted base that deprotonates C60HBn but also as a nucleophile that initiates the nucleophilic addition to the fullerene cage. The structures of the obtained oxazolinated and imidazolinated C60 dimeric compounds have been established by HRMS, UV-vis, and (1)H, (13)C, and HMBC NMR characterizations and computational calculations. The reaction mechanism is studied with the in situ vis-near-IR spectra, which shows that the use of I2 is crucial for the functionalization of the C60 dimer, indicating that it is likely the dimeric molecule rather than the fragment of the dimer that is involved in the reaction. PMID:24188469

Li, Zong-Jun; Li, Shu-Hui; Sun, Tao; Gao, Xiang

2014-01-01

197

An unusual oxidation–dealkylation of 3,4-dihydropyrimidin-2(1 H)-ones mediated by Co(NO 3) 2·6H 2O\\/K 2S 2O 8 in aqueous acetonitrile  

Microsoft Academic Search

4-Aryl-6-methyl-3,4-dihydropyrimidin-2(1H)-one (DHPM) scaffolds of Biginelli type were oxidized using Co(II)\\/S2O82? and the reaction afforded 6-unsubstituted pyrimidin-2(1H)-ones through an unprecedented dealkylation process. 4-Alkyl DHPMs under similar conditions afforded yet another unusual product, ethyl tetrahydropyrimidin-2,4(1H,3H)-dione-5-carboxylate.

Pachaiyappan Shanmugam; Paramasivan T. Perumal

2007-01-01

198

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

199

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

200

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

201

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

202

CCD and IR array controllers  

NASA Astrophysics Data System (ADS)

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

Leach, Robert W.; Low, Frank J.

2000-08-01

203

[In situ IR study of the reaction behavior of clusters [VnCr3-n (mu 3-O) (mu-O2CCH3)6(THF)3]X[n = 0-3, X = Cl-, ClO4-, (VO5)0.5-] and [VnFe3-n(mu 3-O) (mu-O2CCH3)6(THF)3]X(n = 0-3, X = Cl-) in nitrogen atmosphere].  

PubMed

The reaction behavior of the title complexes have been investigated by means of in situ IR in nitrogen atmosphere. It has been found that they enabled the acetic acid to convert to acetone and methane in different temperatures. The results indicate that the sequence of the ketonization reaction activity for the clusters was [V3OAT] > [VFe2OAT], [V2CrOAT] > [Fe3OAT], [VCr2OAT] > [Cr3OAT] [OAT = (mu 3-O) (mu-O2CCH3)6 (THF)3], and the sequence of the methanation reaction activity for the clusters was [Cr3OAT] > [VCr2OAT], [V2CrOAT] > [V3OAT] > [VFe2OAT], [Fe2OAH]. The ketonization reaction activity of [Fe3OAT] were obviously lower than that of [Fe3OAH] [OAH = (mu 3-O) (mu-O2CCH3)6 (H2O)3] and the methanation reaction activity of [Cr3OAT] were also much lower than that of [Cr3OAH]. The difference between [Fe3OAH], [Cr3OAT] and [Fe3OAH], [Cr3OAH] mentioned above were discussed. PMID:12953594

Chen, B; Zhou, W; He, L; Cai, S; Zhang, L

2001-02-01

204

Novel alkynyl substituted 3,4-dihydropyrimidin-2(1H)-one derivatives as potential inhibitors of chorismate mutase.  

PubMed

A series of novel alkynyl substituted 3,4-dihydropyrimidin-2(1H)-one (DHPM) derivatives were designed, synthesized and evaluated in vitro as potential inhibitors of chorismate mutase (CM). All these compounds were prepared via a multi-component reaction (MCR) involving sequential I2-mediated Biginelli reaction followed by Cu-free Sonogashira coupling. Some of them showed promising inhibitory activities when tested at 30?M. One compound showed dose dependent inhibition of CM with IC50 value of 14.76±0.54?M indicating o-alkynylphenyl substituted DHPM as a new scaffold for the discovery of promising inhibitors of CM. PMID:24012092

Mallikarjuna Rao, V; Mahesh Kumar, P; Rambabu, D; Kapavarapu, Ravikumar; Shobha Rani, S; Misra, Parimal; Pal, Manojit

2013-12-01

205

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

PubMed

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

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

2013-12-15

206

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

SciTech Connect

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

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

2012-06-15

207

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

PubMed

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

Abdel Ghani, Nour T; Mansour, Ahmed M

2012-02-01

208

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

209

The O-acylation of ketone enolates by allyl 1H-imidazole-1-carboxylate mediated with boron trifluoride etherate: a convenient procedure for the synthesis of substituted allyl enol carbonates.  

PubMed

A convenient access to substituted allyl enol carbonates was established through the reaction of ketone enolates with the complex of allyl 1H-imidazole-1-carboxylates and boron trifluoride etherate. PMID:17963405

Trost, Barry M; Xu, Jiayi

2007-11-23

210

The O- Acylation of Ketone Enolates by Allyl 1H-imidazole-1-carboxylate Mediated with Boron Trifluoride Etherate---A Convenient Procedure for the Synthesis of Substituted Allyl Enol Carbonates  

PubMed Central

A convenient access to substituted allyl enol carbonates was established through the reaction of ketone enolates with the complex of allyl 1H-imidazole-1-carboxylates and boron trifluoride etherate. PMID:17963405

Trost, Barry M.; Xu, Jiayi

2008-01-01

211

Efficient three-component one-pot synthesis of fully substituted pyridin-2(1H)-ones via tandem Knoevenagel condensation-ring-opening of cyclopropane-intramolecular cyclization.  

PubMed

An efficient synthesis of fully substituted pyridin-2(1H)-ones was developed via three-component one-pot reactions of readily available 1-acetyl-1-carbamoyl cyclopropanes, malononitrile and cyclic secondary amines. PMID:19521633

Liang, Fushun; Cheng, Xin; Liu, Jing; Liu, Qun

2009-06-28

212

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

213

The ?1H Ca2+ Channel Subunit is Expressed in Mouse Jejunal Interstitial Cells of Cajal and Myocytes  

PubMed Central

T-type Ca2+ currents have been detected in cells from the external muscular layers of gastrointestinal smooth muscles and appear to contribute to the generation of pacemaker potentials in interstitial cells of Cajal from those tissues. However, the Ca2+ channel ? subunit responsible for these currents has not been determined. We established that the ? subunit of the ?1H Ca2+ channel is expressed in single myocytes and interstitial cells of Cajal using reverse transcription and polymerase chain reaction from whole tissue, laser capture microdissected tissue, and single cells isolated from the mouse jejunum. Whole cell voltage clamp recordings demonstrated that a nifedipine and Cd2+ resistant, mibefradil-sensitive current is present in myocytes dissociated from the jejunum. Electrical recordings from the circular muscle layer demonstrated that mibefradil reduced the frequency and initial rate of rise of the electrical slow wave. Gene targeted knockout of both alleles of the cacna1h gene, which encodes the ?1H Ca2+ channel subunit, resulted in embryonic lethality due to death of the homozygous knockouts prior to E13.5 days in utero. We conclude that a channel with the pharmacological and molecular characteristics of the?1H Ca2+ channel subunit is expressed in interstitial cells of Cajal and myocytes from the mouse jejunum, and that ionic conductances through the ?1H Ca2+ channel contribute to the upstroke of the pacemaker potential. Furthermore, the survival of mice that do not express the ?1H Ca2+ channel protein is dependent on the genetic background and targeting approach used to generate the knockout mice. PMID:19413888

Gibbons, Simon J.; Strege, Peter R; Lei, Sha; Roeder, Jaime L; Mazzone, Amelia; Ou, Yijun; Rich, Adam; Farrugia, Gianrico

2009-01-01

214

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

215

Decaying neutralino dark matter in anomalous $U(1)_H$ models  

E-print Network

In supersymmetric models extended with an anomalous $U(1)_H$ different R-parity violating couplings can yield an unstable neutralino. We show that in this context astrophysical and cosmological constraints on neutralino decaying dark matter forbid bilinear R-parity breaking neutralino decays and lead to a class of purely trilinear R-parity violating scenarios in which the neutralino is stable on cosmological scales. We have found that among the resulting models some of them become suitable to explain the observed anomalies in cosmic-ray electron/positron fluxes.

D. Aristizabal Sierra; Diego Restrepo; Oscar Zapata

2009-07-03

216

Non anomalous U(1)_H gauge model of flavor  

E-print Network

A non anomalous horizontal $U(1)_H$ gauge symmetry can be responsible for the fermion mass hierarchies of the minimal supersymmetric standard model. Imposing the consistency conditions for the absence of gauge anomalies yields the following results: i) unification of leptons and down-type quarks Yukawa couplings is allowed at most for two generations. ii) The $\\mu$ term is necessarily somewhat below the supersymmetry breaking scale. iii) The determinant of the quark mass matrix vanishes, and there is no strong $CP$ problem. iv) The superpotential has accidental $B$ and $L$ symmetries. The prediction $m_{\\rm up}=0$ allows for an unambiguous test of the model at low energy.

Jesus M. Mira; Enrico Nardi; Diego A. Restrepo

1999-11-03

217

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

218

Syntheses and structures of copper complexes of 3-(6-(1H-pyrazol-1-yl)pyridin-2-yl)pyrazol-1-ide and their excellent performance in the syntheses of nitriles and aldehydes.  

PubMed

Reactions of a pincer ligand 2-(1H-pyrazol-1-yl)-6-(1H-pyrazol-3-yl)pyridine (pzpypzH) with Cu(NO3)2, Cu(ClO4)2, CuSO4, CuCl2 or CuI produced three dinuclear Cu(ii) complexes [{Cu(NO3)}(?-pzpypz)]2 (1), [{Cu(ClO4)}(?-pzpypz)]2 (2), [Cu2(?-SO4)(?-pzpypz)2]·2MeOH (3·2MeOH), one mononuclear Cu(ii) complex [CuCl2(pzpypzH)] (4) and one trinuclear Cu(i)/Cu(ii) complex [(ICu)(?-I)2Cu2(?-pzpypz)2] (5), respectively. Treatment of 4 with two equiv. of AgNO3 in DMF also gave rise to 1. Complexes 1-5 were characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. Complex 1 or 2 has a dimeric structure in which two {Cu(X)} (X = NO3, ClO4) fragments are interconnected by two ?-pzpypz(-) ligands. 3 also adopts a dimeric structure in which two Cu(ii) centers are interconnected by a pair of ?-pzpypz(-) ligands and one ?-SO4(2-) ion. The Cu(ii) center in 4 is five-coordinated by three N atoms of the pzpypzH ligand and two Cl atoms. In 5, two Cu(ii) centers are bridged by two ?-pzpypz(-) ligands and one CuI3(2-) unit, forming a unique trinuclear structure. Complexes 1-5 displayed high catalytic activity toward the ammoxidation of alcohols to nitriles and the aerobic oxidation of alcohols to aldehydes in H2O. The nitrile or aldehyde products could be readily separated from the catalytic system by extraction and the residual aqueous solution containing 1 retained good activity for several cycles. PMID:25119114

Tan, Da-Wei; Xie, Jing-Bo; Li, Qi; Li, Hong-Xi; Li, Jun-Chi; Li, Hai-Yan; Lang, Jian-Ping

2014-10-01

219

Biochemical characteristics, phage patterns, and O1 factor analysis of Escherichia coli O1:K1:H7:F11 and O1:K1:H-:F9 strains isolated from patients with urinary tract infections.  

PubMed

Biochemical characteristics, O1 antigen factors and phage patterns were examined in 35 urinary O1:K1 isolates of Escherichia coli different in H and F antigen. Fermentation of dulcitol, decarboxylation of ornithine, requirement for nicotinamide, and determination of O1 factor d allowed maximum differentiation. On the basis of these tests the strains could be divided into two major groups which are obviously of different clonal origin. Members of clone 1 represented by serotypes O1:K1:H7:F11 (12 strains) and O1:K1:H-:F11 (5 strains) were characterized by positive biochemical reactions and absence of O1 antigen factor d. Negative biochemical tests and presence of O1 antigen factor d were shown by strains of clone 2 which were of serotypes O1:K1:H-:F9 (14 strains) and O1:K1:H-:F- (3 strains). Phage patterns are less well correlated with clonal assignment. However, strains of clone 2 were not susceptible to K1-specific phage D and were non-typable with another set of 13 phages. PMID:6208464

Nimmich, W; Zingler, G

1984-01-01

220

Crystal structure of bis­(1-benzyl-1H-1,2,4-triazole) perchloric acid monosolvate  

PubMed Central

The title compound, 2C9H9N3·HClO4, was prepared by reaction of 1-benzyl-1H-1,2,4-triazole and HClO4 in ethanol at room temperature. The asymmetric unit consists of two mol­ecules of 1-benzyl-1H-1,2,4-triazole and one of HClO4 mol­ecule. The benzene and triazole rings make dihedral angles of 85.45?(8) and 84.76?(8)° in the two mol­ecules. The H-atom position of the perchloric acid mol­ecule is split over two O atoms (real peaks on difference map), with site-occupation factors of 0.5. These H atoms form two classical hydrogen bonds [2.546?(5) and 2.620?(4)?Å] with the same N atoms in both mol­ecules. Five inter­molecular non-classical C—H?O inter­actions, with C?O distances in the range 3.147?(5)–3.483?(5)?Å, are found in the crystal structure. PMID:25553052

Qin, Yong-Qi; Xue, Jin-hui; Qiao, Yuan-Biao; Zhang, Zi-Feng

2014-01-01

221

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

PubMed

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

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

2010-05-01

222

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

223

Polymorphism of IrSn 4  

NASA Astrophysics Data System (ADS)

A high-temperature polymorph of IrSn 4 ( ?-IrSn 4) was prepared from the elements by annealing tin-rich melts at temperatures between 800°C and 900°C and subsequent rapid quenching. The crystal structure of ?-IrSn 4 was determined from single-crystal X-ray data (tetragonal, space group I41/acd, Z=8, a=6.3096(6) Å, c=22.770(7) Å) and corresponds to that of MoSn 4. In ?-IrSn 4, Ir atoms are arranged in layers centering Sn 8 square antiprisms. This is in contrast to the trigonal low-temperature modification ( ?-IrSn 4) where homogeneously distributed Ir atoms are coordinated in a bisdisphenoidal fashion by eight Sn atoms. The structure of ?-IrSn 4, however, is very similar to that of the high-pressure modification of IrSn 4 (HP-IrSn 4), which adopts the PtSn 4 structure. Structural stability of the IrSn 4 polymorphs was investigated by first-principles calculations. It was found that ?-IrSn 4 represents the ground state of the system. At ambient pressure ?-IrSn 4 is 0.027 eV per formula unit (2.61 kJ/mol) higher in energy than ?-IrSn 4. At a pressure of about 5 GPa, our calculations reveal a phase transition ?-IrSn 4? ?-IrSn 4; the latter remains the most stable polymorph up to pressures of at least 10 GPa. Thus, reported HP-IrSn 4 would correspond to a high-pressure-high-temperature form of IrSn 4. However, it is suggested that the structures of HP-IrSn 4 and ?-IrSn 4 are identical.

Nordmark, Eva-Lisa; Wallner, Olle; Häussermann, Ulrich

2002-10-01

224

UVIS and IR Earth Flats  

NASA Astrophysics Data System (ADS)

This program is a continuation of 11914 {UVIS} and 11917 {IR} from Cycle 17. Sunlit earthflats are in program 12710. Visible-wavelength flat fields will be obtained by observing the dark side of the Earth during periods of full moon illumination. The observations will consist of full-frame streaked WFC3 UVIS imagery: per 15-min total exposure time in a single "dark-sky" orbit. Infrared-wavelength flat fields will be obtained by observing the dark side of the Earth during periods of full moon illumination. The observations will consist of full-frame streaked WFC3 IR imagery: per single "dark-sky" orbit, we anticipate achieving Poisson S/N > 100 per pixel in each of three to five exposures, depending on sample sequence {SPARS25 or SPARS50}. The Sunlit Earth is too bright for full frame IR illumination in these filters.

Pavlovsky, Cheryl

2011-10-01

225

23Na and 1H NMR Microimaging of Intact Plants  

NASA Astrophysics Data System (ADS)

23Na NMR microimaging is described to map, for the first time, the sodium distribution in living plants. As an example, the response of 6-day-old seedlings of Ricinus communis to exposure to sodium chloride concentrations from 5 to 300 mM was observed in vivo using 23Na as well as 1H NMR microimaging. Experiments were performed at 11.75 T with a double resonant 23Na- 1H probehead. The probehead was homebuilt and equipped with a climate chamber. T1 and T2 of 23Na were measured in the cross section of the hypocotyl. Within 85 min 23Na images with an in-plane resolution of 156 × 156 ?m were acquired. With this spatial information, the different types of tissue in the hypocotyl can be discerned. The measurement time appears to be short compared to the time scale of sodium uptake and accumulation in the plant so that the kinetics of salt stress can be followed. In conclusion, 23Na NMR microimaging promises great potential for physiological studies of the consequences of salt stress on the macroscopic level and thus may become a unique tool for characterizing plants with respect to salt tolerance and salt sensitivity.

Olt, Silvia; Krötz, Eva; Komor, Ewald; Rokitta, Markus; Haase, Axel

2000-06-01

226

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

227

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

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

228

Inhibition of myeloperoxidase: Evaluation of 2H-indazoles and 1H-indazolones.  

PubMed

Myeloperoxidase (MPO) produces hypohalous acids as a key component of the innate immune response; however, release of these acids extracellularly results in inflammatory cell and tissue damage. The two-step, one-pot Davis-Beirut reaction was used to synthesize a library of 2H-indazoles and 1H-indazolones as putative inhibitors of MPO. A structure-activity relationship study was undertaken wherein compounds were evaluated utilizing taurine-chloramine and MPO-mediated H2O2 consumption assays. Docking studies as well as toxicophore and Lipinski analyses were performed. Fourteen compounds were found to be potent inhibitors with IC50 values <1?M, suggesting these compounds could be considered as potential modulators of pro-oxidative tissue injury pertubated by the inflammatory MPO/H2O2/HOCl/HOBr system. PMID:25438766

Roth, Aaron; Ott, Sean; Farber, Kelli M; Palazzo, Teresa A; Conrad, Wayne E; Haddadin, Makhluf J; Tantillo, Dean J; Cross, Carroll E; Eiserich, Jason P; Kurth, Mark J

2014-11-15

229

/sup 1/H NMR studies of the sol-gel transition  

SciTech Connect

High resolution /sup 1/H NMR spectroscopy has been employed to study the dynamics of the sol-gel transition in simple silicates. High magnetic fields (360 MHz) were used to detect and identify the various chemical species present in the Si(OCH/sub 2/CH/sub 3/)/sub 4/:C/sub 2/H/sub 5/OH:H/sub 2/O and Si(OCH/sub 3/)/sub 4/:CH/sub 3/OH:H/sub 2/O sol-gel systems. Using these techniques, the time evolution of the reactant and product species were monitored. Results of these studies have shown that acid and base catalyzed systems react along very different chemical pathways and that the elementary hydrolysis and condensation reactions occur on widely different time scales. The use of these experimental data to test possible mechanisms is discussed.

Assink, R.A.; Kay, B.D.

1984-01-01

230

Phosphorylation of IRS proteins, insulin action, and insulin resistance.  

PubMed

Insulin signaling at target tissues is essential for growth and development and for normal homeostasis of glucose, fat, and protein metabolism. Control over this process is therefore tightly regulated. It can be achieved by a negative feedback control mechanism whereby downstream components inhibit upstream elements along the insulin-signaling pathway (autoregulation) or by signals from apparently unrelated pathways that inhibit insulin signaling thus leading to insulin resistance. Phosphorylation of insulin receptor substrate (IRS) proteins on serine residues has emerged as a key step in these control processes under both physiological and pathological conditions. The list of IRS kinases implicated in the development of insulin resistance is growing rapidly, concomitant with the list of potential Ser/Thr phosphorylation sites in IRS proteins. Here, we review a range of conditions that activate IRS kinases to phosphorylate IRS proteins on "hot spot" domains. The flexibility vs. specificity features of this reaction is discussed and its characteristic as an "array" phosphorylation is suggested. Finally, its implications on insulin signaling, insulin resistance and type 2 diabetes, an emerging epidemic of the 21st century are outlined. PMID:18728222

Boura-Halfon, Sigalit; Zick, Yehiel

2009-04-01

231

Heterocalixarenes. Part 2. Calix[m]uracil[n]benzimidazol-2(1H)-one[3] arenes: Synthesis and Binding Characteristics  

Microsoft Academic Search

The reactions of uracil\\/benzimidazol-2(1H)-one with 1,3-bis(bromomethyl)benzene provide respectively1 3-bis[(3-bromomethylbenzene)methyl]uracil\\/benzimidazol-2(1H)-onewhich on subsequent cyclization with1,3-bis[(uracil-1-yl\\/benzimidazol-2(1H)-one-1-yl)methyl]benzenederivatives provide respectively calix[m]uracil[n]benzimidazoI-2(1H)-one[3]arenes[m =3, n = 0 (9); m = 2, n = 1 (10);m = 1, n = 2 (11) and m = 0, n = 3 (12)]. The heterocalixarenes 9–12, both in liquid–liquid and solid–liquid extraction experiments, selectively extract ammonium picrates over the similarly sized

Subodh Kumar; Dharam Paul; Harjit Singh

2000-01-01

232

Detection of IR target by fusing multispectral IR data  

NASA Astrophysics Data System (ADS)

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

Li, Liya; Qi, Meng; Gao, Xuhui

2011-08-01

233

BaIrIn4 and Ba2Ir4In13: two In-rich polar intermetallic structures with different augmented prismatic environments about the cations.  

PubMed

The title phases were synthesized via high-temperature reactions of the elements in welded Ta tubes and characterized by single-crystal X-ray diffraction methods and band calculations. BaIrIn4 adopts the LaCoAl4-type structure: Pmma, Z = 2, a = 8.642(2), b = 4.396(1), and c = 7.906(2) A. Ba2Ir4In13 exhibits a new structure type: Cmc2(1), Z = 4, a = 4.4856(9), b = 29.052(6), and c = 13.687(3) A. BaIrIn4 is constructed from a single basic unit, a Ba-centered pentagonal prism of indium on which two adjacent and the opposed rectangular faces are capped by In and Ir, respectively. The three capping atoms are coplanar with Ba and represent the only augmentation of the pentagonal prism. The relatively large proportions of Ba:Ir, In, and of In:Ir lead to the condensation of homoatomic pentagonal prisms into zigzag chains through the sharing of the two uncapped faces. The cation proportion is much lower in Ba2Ir4In13, and Ba atoms are surrounded by a more anionic Ir/In network without any condensation between prisms. This and the greater Ir proportion lead to a network of formal augmented pentagonal Ba@Ir5In15 and hexagonal Ba@Ir7In15 prisms with overall 5-10-5 and 6-10-6 arrangements of parallel planar rings, respectively, although most Ir is not well bound to the prisms. The latter prism, with alternating Ir/In atoms in the basal faces, is novel for Ae-T-In phases (Ae = alkaline-earth metal, T = Co, Rh, Ir). Band structure calculation results (linear-muffin-tin-orbital method in the atomic sphere approximation) emphasize the greater overlap populations (approximately strengths) of the Ir-In bonds and confirm expectations that both compounds are metallic. The Ir 5d bands are narrower and lie higher in energy than those for Au in analogous phases. PMID:18795775

Palasyuk, Andriy M; Corbett, John D

2008-10-20

234

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

235

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.

236

Atmospheric Entry Experiments at IRS  

Microsoft Academic Search

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

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

2002-01-01

237

Pirmoji ir antroji kauno trianguliacijos  

NASA Astrophysics Data System (ADS)

Miesto plan? sudarymo reikm?ms atramos punkt? tinklas tarpukariu Europos valstyb?se buvo formuojamas trianguliacijos metodu. Kauno pirm? kart? 1924 m. jis buvo suprojektuotas iš 36 punkt?, fiksuotas vietov?je ir išmatuotas inž. Z. Ba?elio. Sudarytas trianguliacijos tinklas ap?m? tuometin? Vilijampol?s, Aleksoto, Žaliakalnio, Naujamies?io ir Žem?j? Šan?i? teritorij?. Kaunas, tap?s laikin?ja sostine, spar?iai augo, d?l to pirmoji trianguliacija netenkino poreiki?: dauguma punkt? vietov?je nebuvo išsaugoti, miestas dvigubai išsipl?t?, d?l naudot? geodezini? prietais? nepakankamas buvo punkt? tikslumas. Naujas tinklas buvo suprojektuotas taip, kad vienam punktui vidutini\\vskai tekt? vienas kvadratinis kilometras miesto ploto ir b?t? užtikrintas ?tvirtint? punkt? 10 cm ribinis tikslumas. Kauno antrosios trianguliacijos realizavimo nuopelnai priskirtini Kauno savivaldyb?s Matavim? dalies specialistams - ved?jui J. Deksniui ir jo pavaduotojui J. Ašmonui.

Girkus, Romualdas; Urbanavi?ius, Valdas

2010-01-01

238

Catalyst-free synthesis of 2-aryl-1,2-dihydro-quinazolin-4(1H)-thiones from 2-aminobenzothio-amides and aldehydes in water.  

PubMed

2-Dihydroquinazolin-4(1H)-thiones were prepared in up to excellent yields from 2-aminobenzothioamides and aldehydes. The reaction is carried out in water without the use of any catalyst or promoter. The sulfur-containing substrate can be obtained easily by thiation of the corresponding nitrile by solid sodium hydrosulfide. PMID:25425141

Oschatz, Stefan; Brunzel, Tom; Wu, Xiao-Feng; Langer, Peter

2015-01-28

239

Brønsted Acidic Ionic Liquid: An Efficient and Reusable Catalyst for the Synthesis of 3,4?Dihydropyrimidin?2(1H)?ones  

Microsoft Academic Search

A novel ionic liquid, 3?carboxymethyl?1?methylimidazolium bisulfate (CMImHSO4), was synthesized and used as a recyclable catalyst for the Biginelli reaction under solvent?free conditions. High yields of various substituted 3,4?dihydropyrimidin?2(1H)?ones (or thiones) were obtained. The ionic liquid can be recovered and recycled easily without loss of activity.

Renwei Zheng; Xiaoxia Wang; Hui Xu; Jingxing Du

2006-01-01

240

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

SciTech Connect

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

Yueksektepe, Cigdem, E-mail: yuksekc@yahoo.com [Cankiri Karatekin University, Department of Physics, Faculty of Science (Turkey); Caliskan, Nezihe [Ondokuz Mayis University, Department of Physics, Faculty of Arts and Sciences (Turkey); Genc, Murat [Adiyaman University, Department of Chemistry, Faculty of Arts and Sciences (Turkey); Servi, Sueleyman [Firat University, Department of Chemistry, Faculty of Science (Turkey)

2010-12-15

241

Kiauli? reprodukcijos ir kv?pavimo sindromo viruso (KRKSV) epidemiologiniai tyrimai Lietuvos šern? ir kiauli? populiacijose.  

E-print Network

??Disertacinio darbo tikslas buvo imunologiniais ir molekuliniais metodais ?vertinti kiauli? reprodukcijos ir kv?pavimo sindromo (KRKSV) infekcijos epidemiologin? situacij? 2008-2011 met? laikotarpiu Lietuvos šern? ir kiauli?… (more)

Buitkuvien?, J?rat?

2013-01-01

242

Drug Reactions  

MedlinePLUS

... version Drug Reactions Drug Reactions What is an adverse drug reaction? Medicines can treat or prevent illness and ... medicines can cause problems. These problems are called adverse drug reactions. You should know what to do if ...

243

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

2014-12-23

244

High field /sup 1/H NMR studies of sol-gel kinetics. [Tetramethylonthosilicate in methanol and water  

SciTech Connect

High resolution /sup 1/H NMR spectroscopy at high magnetic fields is employed to study the reaction of the Si(OCH/sub 3/)/sub 4/:CH/sub 3/OH:H/sub 2/O sol-gel system. Both the overall extent of reaction as a function of time and the equilibrium distribution of species are measured. In acid catalyzed solution, condensation is the rate limiting step while in base catalyzed solution, hydrolysis becomes rate limiting. A kinetic model in which the rate of hydrolysis is assumed to be independent of the adjacent functional groups is presented. This model correctly predicts the distribution of product species during the initial stages of the sol-gel reaction.

Kay, B.D.; Assink, R.A.

1986-01-01

245

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

PubMed

Benzimidazoles are important compounds because of their antibacterial, antifungal, antimicrobial, antiprotozoal and antihelmintic activities. Some benzimidazole derivatives also interfere with the reactions of DNA topoisomerases, enzymes functioning at almost all stages of the cell cycle. In this study, nine 1H-benzimidazole derivatives with substituents at positions 2 and 5 were synthesized and the structure of the compounds was elucidated by instrumental methods. The characterized compounds were screened to identify if they interfered with mammalian type I DNA topoisomerase activity via in vitro supercoil relaxation assays. Selected compounds were subjected to cytostatic assays using HeLa (cervix adenocarcinoma), MCF7 (breast adenocarcinoma) and A431 (skin epidermoid carcinoma) cells. Our results showed that 5-chloro-2-(2-hydroxyphenyl)-1H-benzimidazole exerted the most profound topoisomerase I inhibition and cytotoxicity. PMID:18692939

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

2009-05-01

246

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

247

IR and NMR Studies on the Action of Hypochlorous Acid on Chondroitin Sulfate and Taurine  

Microsoft Academic Search

Although it has been recently shown by the use of1H nuclear magnetic resonance (1H NMR) spectroscopy that enzymatically formed hypochlorous acid (HOCl\\/Cl?) reacts with carbohydrates containingN-acetyl groups under the formation of acetate and presumably chloramines, mechanistical aspects of this reaction remain unknown. Since NMR spectroscopy suffers a lot from low sensitivity especially toward polymeric components giving less marked resonances, we

Roland Servaty; Jürgen Schiller; Hans Binder; Bernd Kohlstrunk; Klaus Arnold

1998-01-01

248

A highly selective fluorescent chemosensor for iron ion based on 1H-imidazo [4,5-b] phenazine derivative.  

PubMed

Two kinds of fluorescent sensors (S and S1) for Fe(3+) bearing 1H-Imidazo [4,5-b] phenazine derivatives have been designed and synthesized. Between the two sensors, S showed excellent fluorescent specific selectivity and high sensitivity for Fe(3+) in DMSO solution. The test strip based on S was fabricated, which could act as a convenient and efficient Fe(3+) test kit. The recognition mechanism of the sensor toward Fe(3+) was evaluated by MS, IR and XRD. The detection limit of the sensor S towards Fe(3+) is 4.8×10(-6)M. And other cations, including Hg(2+),Ag(+), Ca(2+), Cu(2+), Co(2+), Ni(2+), Cd(2+), Pb(2+), Zn(2+), Cr(3+), and Mg(2+) had no influence on the probing behavior. PMID:24291427

Gao, Guo-ying; Qu, Wen-juan; Shi, Bing-bing; Zhang, Peng; Lin, Qi; Yao, Hong; Yang, Wen-long; Zhang, You-ming; Wei, Tai-bao

2014-01-01

249

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

250

Preparation of Pt/Irx(IrO2)10 - x bifunctional oxygen catalyst for unitized regenerative fuel cell  

NASA Astrophysics Data System (ADS)

Bifunctional Pt/Irx(IrO2)10 - x (x < 10) catalyst for unitized regenerative fuel cell (URFC) has been prepared by depositing Pt on Irx(IrO2)10 - x support which is obtained initially from Adams fusion method. X-ray diffraction and transmission electron microscopy show that ultrafine and narrow distributed Pt/Ir3(IrO2)7 nanocomposites are formed. Electrochemical measurements demonstrate that among the series of catalysts studied, Pt/Ir3(IrO2)7 catalyst possesses the highest electrochemical surface area (24.74 m2 g-1) and the highest activity towards oxygen reduction reaction (ORR) (21.71 mA mg-1 at 0.85 V). Meanwhile, considerably high activity towards oxygen evolution reaction (OER) (42.35 mA mg-1 at 1.55 V) is also observed for Pt/Ir3(IrO2)7 catalyst. Kinetic analyses indicate that ORR on Pt/Ir3(IrO2)7 catalyst follows four-electron mechanism. This work opens a new way to fabricate efficient bifunctional oxygen catalyst for URFC.

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

2012-07-01

251

Application of progress curve analysis to in situ enzyme kinetics using 1H NMR spectroscopy.  

PubMed

The steady-state kinetics of enzymes in tissues, cells, and concentrated lysates can be characterized using high-resolution nuclear magnetic resonance spectroscopy; this is possible because almost invariably there are differences in the spectra of substrates and products of a reaction and these spectra are obtainable even from optically opaque samples. We used 1H spin-echo NMR spectroscopy to study the hydrolysis of alpha-L-glutamyl-L-alanine by cytosolic peptidases of lysed human erythrocytes. Nonlinear regression of the integrated Michaelis-Menten expression onto the progress-curve data yielded, directly, estimates of Vmax and Km for the hydrolase; a procedure for analyzing progress curves in this manner was adapted and compared with a commonly used procedure which employs the Newton-Raphson algorithm. We also performed a sensitivity analysis of the integrated Michaelis-Menten expression; this yielded equations that indicate under what conditions estimates of Km and Vmax are most sensitive to variations in experimental observables. Specifically, we showed that the most accurate estimates of the steady-state parameters from analysis of progress curves are obtained when the initial substrate concentration is much greater than Km. Furthermore, estimates of these parameters obtained by such an analysis are most sensitive to data obtained when the reaction is 60-80% complete, having started with the highest practicable initial substrate concentration. PMID:3013046

Vandenberg, J I; Kuchel, P W; King, G F

1986-05-15

252

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

253

Protein Dynamics Research Station on IR Beam Line of MIRRORCLE-20  

NASA Astrophysics Data System (ADS)

The purpose of our study is to examine the molecular dynamics under synchrotron radiation with wavelength in far infrared region that has not yet been applied. Yamada and collaborators have succeeded in developing tabletop synchrotron light sources having 15 cm orbit radius for brilliant IR radiation named "MIRROCLE-20". The IR radiation from the entire electron orbit of exact circular is collected by circular mirror and quasi-ellipsoidal mirror. The IR synchrotron light spectrum is centered at 10 ?m wavelength and covers from few to 100 ?m. The unique beam line is the monochromatic IR irradiation system, which was unable before due to the limited IR irradiation system. We are constructing the dispersive type monochrometer with gratings that reveals 1 to 1/2 % bands monochromatic IR-rays. Specimens are placed along 15 cm long focal plane with 30 chambers, where monochromatic IR-rays are applied through slits with 1 mm width. We have a plan to detect chemical products due to the high flux IR irradiation with specific wavelength to the proteins in water. Molecular dynamics and enzymatic reaction under IR or FIR radiation have not yet been fully understood. Generally speaking, intramolecular vibration mode will be spread and finally transfer into thermal energy. Our research object is to clarify the relaxation process of the vibration energy and to control the chemical reactions through excitation of certain vibration mode of the target proteins with monochromatic IR rays. The structural change in the proteins will be detected by its chemical products as well as change in absorption and emission spectra. Sample in our mind is for instance Horseradish peroxidase (HRP).

Kikuzawa, T.; Yamada, H.; Mochizuki-Oda, N.; Miura, N.; Moon, A.

2004-08-01

254

Characterization of a reverse micellar system by 1H NMR.  

PubMed

The (1)H NMR spectrum of IgepalCO520 in ternary mixtures containing water and cyclohexane shows a complex dependence on water content. This is in part because of rapid exchange between surfactant molecules within the micelles and free surfactant dissolved in the continuous phase. The analysis of this two-state system is further complicated by the fact that the chemical shifts of both free and micellar surfactants vary with micelle size. We demonstrate that the relative quantities of free and micellar surfactants can be determined from the NMR spectra if the data are compared within sample sets of constant micelle size but differing global composition. By fixing micelle size, the spectra of both surfactant states remain constant within a given series and only the relative populations of the free and micellar species change with overall composition. This method of analysis allows for the determination of free surfactant concentration as a function of micelle size. Results are presented for the water/IgepalCO520/cyclohexane system and indicate that the free surfactant concentration is far from negligible and strongly dependent on micelle size. The free surfactant concentration increases with decreasing micelle size, reflecting the lower stability of the smaller micelles. Similar behavior can be expected for other reverse micellar systems based on non-ionic surfactants. PMID:20099857

Lemyre, Jean-Luc; Ritcey, Anna M

2010-05-01

255

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

256

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

257

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

258

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

259

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 spectrum of a mixture of species. I. Introduction Ultrafast 2D IR vibrational echo spectroscopy1

Fayer, Michael D.

260

Compact hybrid IR\\/UV biological sensor  

Microsoft Academic Search

The sensor is a hybrid IR\\/UV lidar system that maps aerosol clouds, measures cloud wind speed and direction, and determines whether the cloud fluoresces. It is being developed by EOO, Inc. and SRI International under a DARPA SBIR. The hybrid IR\\/UV lidar system was conceived to operate from a small UAV platform for tactical battlefield missions. The IR sensor can

Donald A. Leonard; James F. Shaw; Christopher Smith; Paul J. Titterton; Norm Neilson; Russ Scofield; Sylvie A. Carlisle; Russell E. Warren; David E. Cooper

1999-01-01

261

Localized 1H MR Spectroscopy in the alert monkey at 7 Tesla J. Pfeuffer1  

E-print Network

Localized 1H MR Spectroscopy in the alert monkey at 7 Tesla J. Pfeuffer1 , C. Juchem1 , H. Merkle2/NINDS, Bethesda, MD, United States Introduction MR imaging and spectroscopy in monkeys promises to build a bridge-voxel 1 H MRS in the alert monkey using a 7 T MR system with a vertical bore. Typically

Jegelka, Stefanie

262

Oxidation of 1,4-Dihydropyridines and 3,4-Dihydropyrimidin-2(1H)-ones to Substituted Pyridines and Pyrimidinones Using Ca(OCl)2 in Aqueous Media  

Microsoft Academic Search

Abstract1,4-Dihydropyridines and 3,4-dihydropyrimidin-2(1H)-ones obtained from the Hantzsch and Biginelli reactions undergo readily oxidative dehydrogenation by using calcium hypochlorite in very short times. These calcium stimulator drugs were oxidized under reaction conditions next to the in vivo transformations at room temperature.

Fatemeh Tamaddon; Zahra Razmi

2011-01-01

263

Design of a biosensor based on 1-(4-nitrophenyl)-2,5-di(2-thienyl)-1 H pyrrole  

Microsoft Academic Search

Immobilization of polyphenol oxidase (tyrosinase, E.C. 1.14.18.1) was achieved on a copolymer of 1-(4-nitrophenyl)-2,5-di(2-thienyl)-1H-pyrrole [SNS(NO2)] with pyrrole ([SNS(NO2)]\\/PPy) via electrochemical polymerization. Two different substrates; catechol and l-tyrosine were used for the characterization of biosensor. The kinetic parameters of the biosensor, maximum reaction rate of the enzyme (Vmax) and Michaelis–Menten constant (Km) were determined for two different substrates. Vmax was found

Sevinc Tuncagil; Serhat Varis; Levent Toppare

2010-01-01

264

1H, 13C NMR and X-ray crystallographic studies of highly polyhalogenated derivatives of costunolide lactone  

NASA Astrophysics Data System (ADS)

The costunolide lactone, a sesquiterpene compound isolated from Zaluzania triiloba species, reacted with several dihalocarbene sources produced by trihaloform-NaOH under successive phase transfer reactions yielding mono-, bis- and tris-dihalocyclopropane adducts. The structures, as well as the configurational assignments of the different derivatives, were established by 1H and 13C NMR spectroscopy and assisted by X-ray crystallographic and molecular modelling studies. The specific shielding of protons in the neighbourhood of different halogens on the cyclopropane moieties was correlated to the pseudocontact interactions.

Corona, D.; Díaz, E.; Nava, J. L.; Guzmán, A.; Barrios, H.; Fuentes, A.; Hernandez-Plata, S. A.; Allard, J.; Jankowski, C. K.

2005-11-01

265

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

PubMed Central

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

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

2006-01-01

266

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

E-print Network

Enhanced anhydrous proton conduction in binary mixtures of 1H-imidazole­1H-1,2,3-triazole based.1039/c2jm32835f What is the impact of mixing two proton-conducting heterocycles on proton conductivity that mixtures of molecules 4 and 10 at certain compositions show enhanced proton conductivity compared

Auerbach, Scott M.

267

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

PubMed

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

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

2013-10-21

268

One-pot synthesis, FT-IR, NMR and density functional method (B3LYP) studies on 2-(cyclohexylamino)-2-oxo-1-(pyridin-2-yl)ethyl benzoate  

Microsoft Academic Search

\\u000a2-(cyclohexylamino)-2-oxo-1-(pyridin-2-yl)ethyl benzoate has been synthesized and characterized by elemental analysis, FT-IR,1H NMR and 13C NMR. Geometrical structures, vibrational frequencies, 1H and 13C chemical shift values, molecular electrostatic potential maps and several thermodynamic parameters of title compound in the ground state have been calculated by using the density functional method with 6-31G(d) basis set. The IR spectrum of title compound was

E. Vessally; E. Fereyduni; E. Yaaghubi; N. Sundaraganesan

2011-01-01

269

Synthesis, characterization and antimicrobial activity of a Zn(II) complex with 1-(1H-benzoimidazol-2-yl)-ethanone thiosemicarbazone  

Microsoft Academic Search

A new Zn(II) complex with 1-(1H-benzoimidazol-2-yl)-ethanone thiosemicarbazone [Zn(NO3)(H2O)(C10H11N5S)]NO3 was prepared and characterized by elemental analyses, FT-IR, H NMR spectroscopy, thermogravimetric analysis (TGA), X-ray diffraction (XRD), and single-crystal X-ray diffraction analysis. The coordination geometry of the pentacoordinated zinc is a distorted square pyramid. The antimicrobial activity of the complex was evaluated using a broth micro-dilution method against a panel of human

Mehmet Poyraz; Musa Sar?; Ayse Güney; Fatih Demirci; Seref Demirayak; Ertan ?ahin

2008-01-01

270

Near-IR Photometry of Nova Del 2013  

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

271

FRAP-Dependent Serine Phosphorylation of IRS-1 Inhibits IRS-1 Tyrosine Phosphorylation  

Microsoft Academic Search

We have previously shown that interferon-? (IFN?)-dependent tyrosine phosphorylation of insulin receptor substrate-1 (IRS-1) is impaired by serine phosphorylation of IRS-1 due to the reduced ability of serine phosphorylated IRS-1 to serve as a substrate for Janus kinase 1 (JAK1). Here we report that FKBP12–rapamycin-associated protein (FRAP) is a physiologic IRS-1 kinase that blocks IFN? signaling by serine phosphorylating IRS-1.

Matthew E. Hartman; Montserrat Villela-Bach; Jie Chen; Gregory G. Freund

2001-01-01

272

IR susceptibility of naval ships using ShipIR/NTCS  

NASA Astrophysics Data System (ADS)

Methods of analysing the signature and susceptibility of naval platforms to infrared detection are described. An unclassified ShipIR destroyer model is used to illustrate the primary sources of infrared signature and detection: the exhaust system, solar-heating, and operating climate. The basic detection algorithm used by the Naval Threat Countermeasure Simulator (NTCS) component of ShipIR is described and used to analyse the effectiveness of various stealth technologies: stack suppression, low solar absorptive (LSA) paints, and Active Hull Cooling (AHC). Standard marine climate statistics are used to determine a minimum (5%), average (50%) and maximum (95%) signature condition for each operating region. The change in detection range of two wave-band sensors (3-5?m, 8-12 ?m) operating at different altitudes (10m, 270m) in each of four climatic conditions is used to assess the effectiveness of each stealth solution, providing a more integral approach to infrared stealth design. These tools and methods form the basis on which future platform designs are being evaluated.

Vaitekunas, David A.

2010-04-01

273

Data Compression for IR Reconnaissance  

NASA Astrophysics Data System (ADS)

Recent trends in airborne reconnaissance force the designers of IR reconnaissance sensors to study data compression methods so that the sensors can be more efficiently interfaced with real time data links and with magnetic recorders. The previous successful efforts in compressing FLIR data are briefly noted. Infrared line scanners have only recently become candidates for data compression. Some of the requirements and problems are noted for compressing line scan data. Applicable methods are presented, and a hybrid DPCM/Huffman Coder is described with some successful results.

McCracken, William

1985-12-01

274

High-performance IR cameras  

NASA Astrophysics Data System (ADS)

Aerojet has developed high performance infrared (IR) cameras based on Kodak's 640 by 486 pixels platinum silicide (PtSi) array. Several versions of the camera have been developed for the various applications. The cameras have multiple field-of-view (FOV) optics, with the narrow FOV used for long range observation. The use of the large array of PtSi leads to very high image quality as well as high resolution. The operation in the medium-wavelength infrared (MWIR) allows observation at very long ranges in high humidity, warm atmospheres. Field tests have shown the advantage of these cameras, particularly in coastal and marine applications.

Shaham, Yifal J.; Schellhase, R.

1996-06-01

275

IR excesses in Be stars  

NASA Technical Reports Server (NTRS)

Infrared excesses are empirically derived for a sample of bright Be stars based on IRAS data and previously published near-infrared photometry. The excesses are compared with published H-alpha luminosities and are found to be correlated. The data are compared with the theoretically expected relation between the sum of free-free and free-bound continua and the H-alpha recombination-line intensity from a common envelope. The inclusion of temperature and optical-depth effects is necessary to produce agreement between observations and theory. No significant correlation is detected between L(IR)/L(H-alpha) ratios and rotational velocities.

Chokshi, Arati; Cohen, Martin

1987-01-01

276

Sam68 interacts with IRS1.  

PubMed

Sam68 (Src associated in mitosis) is a RNA binding protein that links cellular signaling to RNA processing. In previous studies we found that insulin promotes Sam68 relocalization in the cytoplasm allowing Sam68 to associate with p85PI3K, Grb2, GAP and probably the insulin receptor (IR), modulating insulin action positively. In the present work, we wanted to define the role of Sam68 in the first stages of IR signaling. Both BRET and co-immunoprecipitation assays have been used for the study of Sam68 binding to IR, IRS1 and p85-PI3K. BRET saturation experiments indicated, for the first time, that Sam68 associates with IRS1 in basal condition. To map the region of Sam68 implicated in the interaction with IRS1, different Sam68 mutants deleted in the proline-rich domains were used. The deletion of P0, P1 and P2 proline rich domains in N-terminus as well as P4 and P5 in C-terminus of Sam68 increased BRET(50), thus indicating that the affinity of Sam68 for IRS1 is lower when these domains are missing. Moreover, in IR-transfected HEK-293 cells, BRET saturation experiment indicated that insulin increases the affinity between Sam68-Rluc and IRS1-YFP. In conclusion, our data indicate that Sam68 interacts with IRS-1 in basal conditions, and insulin increases the affinity between these two partners. PMID:22005517

Quintana-Portillo, R; Canfrán-Duque, A; Issad, T; Sánchez-Margalet, V; González-Yanes, C

2012-01-01

277

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

278

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

279

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

280

Absence of structural transition in M0.5IrTe2 (M = Mn, Fe, Co, Ni)  

NASA Astrophysics Data System (ADS)

M-doped IrTe2 (M = Mn, Fe, Co, Ni) compounds were synthesized by solid-state reaction. Single crystal x-ray diffraction experiments indicate that part of the doped M ions (M = Fe, Co, and Ni) substitute for Ir, and the rest intercalate into the octahedral interstitial sites located in between IrTe2 layers. Due to the lattice mismatch between MnTe2 and IrTe2, Mn has limited solubility in IrTe2 lattice. The trigonal structure is stable in the whole temperature range 1.80 K? T ? 300 K for all doped compositions. No long-range magnetic order or superconductivity was observed in any doped compositions above 1.80 K. A spin glass behavior below 10 K was observed in Fe-doped IrTe2 from the temperature dependence of magnetization, electrical resistivity, and specific heat. The low temperature specific heat data suggest the electron density of states is enhanced in Fe- and Co-doped compositions but reduced in Ni-doped IrTe2. With the 3d transition metal doping the trigonal a-lattice parameter increases but the c-lattice parameter decreases. Detailed analysis of the single crystal x-ray diffraction data shows that interlayer Te-Te distance increases despite a reduced c lattice. The importance of the Te-Te, Te-Ir, and Ir-Ir bonding is discussed.

Yan, J.-Q.; Saparov, B.; Sefat, A. S.; Yang, H.; Cao, H. B.; Zhou, H. D.; Sales, B. C.; Mandrus, D. G.

2013-10-01

281

Properties of the transition metal dichalcogenides: The case of IrS sub 2 and IrSe sub 2  

SciTech Connect

The syntheses and structure determination of IrSe{sub 2} and IrS{sub 2} were undertaken. Pure phases were obtained and powder data were measured on an X-ray diffractometer. Rietveld refinement was successfully carried out for both structures (IrSe{sub 2}, 269 observations R (weighted profile) 0.062; IrS{sub 2}, 205 observations R (weighted profile) 0.074). The Pnam space group (No. 62) was found to yield the best results, eliminating Pna2{sub 1} as the other possible space group considered in a previous study of IrSe{sub 2}. Chalcogen pairs are found in both structures and these may correspond, in a first approach, to the charge balance Ir{sup 3+}X{sup 2{minus}}(X{sub 2}){sup 2{minus}}{sub 1/2}. However, long bond lengths were found in the chalcogen pairs (S-S 2.299(11) {angstrom}, Se-Se 2.555(4) {angstrom}) along with an unexpectedly small effective cationic radius of 0.50 {angstrom} for Ir{sup 3+}. These features of IrS{sub 2} and IrSe{sub 2} are discussed.

Jobic, S.; Deniard, P.; Brec, R.; Rouxel, J. (Institut de Physique et Chimie des Materiaux, Nantes (France)); Drew, M.G.B. (The University, Reading (England)); David, W.I.F. (Rutherford Appleton Laboratory, Didcot (England))

1990-12-01

282

3D 15N/15N/1H chemical shift correlation experiment utilizing an RFDR-based 1H/1H mixing period at 100 kHz MAS  

NASA Astrophysics Data System (ADS)

Homonuclear correlation NMR experiments are commonly used in the high-resolution structural studies of proteins. While 13C/13C chemical shift correlation experiments utilizing dipolar recoupling techniques are fully utilized under MAS, correlation of the chemical shifts of 15N nuclei in proteins has been a challenge. Previous studies have shown that the negligible 15N-15N dipolar coupling in peptides or proteins necessitates the use of a very long mixing time (typically several seconds) for effective spin diffusion to occur and considerably slows down a 15N/15N correlation experiment. In this study, we show that the use of mixing proton magnetization, instead of 15N, via the recoupled 1H-1H dipolar couplings enable faster 15N/15N correlation. In addition, the use of proton-detection under ultrafast MAS overcomes the sensitivity loss due to multiple magnetization transfer (between 1H and 15N nuclei) steps. In fact, less than 300 nL (?1.1 micromole quantity) sample is sufficient to acquire the 3D spectrum within 5 h. Our results also demonstrate that a 3D 15N/15N/1H experiment can render higher resolution spectra that will be useful in the structural studies of proteins at ultrafast MAS frequencies. 3D 15N/15N/1H and 2D radio frequency-driven dipolar recoupling (RFDR)-based 1H/1H experimental results obtained from a powder sample of N-acetyla-L-15N-valyl-L-15N-leucine at 70 and 100 kHz MAS frequencies are presented.

Nishiyama, Yusuke; Malon, Michal; Ishii, Yuji; Ramamoorthy, Ayyalusamy

2014-07-01

283

Reaction times  

Microsoft Academic Search

Reviews 11 studies dealing with reaction times (1910-1911). Reaction time has been utilized to study a variety of problems. The studies indicate that accurate results can not be obtained without careful attention to the technique of the method of reaction time. The topics covered include effect of intensity of stimulus on reaction time, rapidity of perception of sound and light

Herbert Woodrow

1911-01-01

284

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

SciTech Connect

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

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

2010-11-01

285

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

286

Resistance and Susceptibility Anomalies in IrTe 2 and CuIr 2 Te 4  

Microsoft Academic Search

IrTe2has the CdI2structure and CuIr2Te4has a defect-NiAs structure at room temperature. Both compounds show basically metallic behavior. Magnetic and resistance anomalies, showing a hysteresis in temperature, have been found in IrTe2and CuIr2Te4. On heating, the resistivity ? exhibits a hump-shaped maximum around 270 and 250 K for IrTe2and CuIr2Te4, respectively. The magnetic susceptibility ? reveals a step-like anomaly which gives

Nobuhiro Matsumoto; Kouji Taniguchi; Ryo Endoh; Hideaki Takano; Shoichi Nagata

1999-01-01

287

High Resolution 1H Detected 1H,13C Correlation Spectra in MAS Solid-State NMR using Deuterated Proteins with Selective 1  

E-print Network

in the crystallization buffersresulted in a 4-fold reduction in the 1H line width (compared to a sample recrystallized,13C]-labeled pyruvate as the sole carbon source. Methyl groups of alanine, valine, leucine

Skrynnikov, Nikolai

288

Dust Content in Compact HII Regions (NGC 7538 -- IRS 1, IRS 2, and IRS 3)  

NASA Astrophysics Data System (ADS)

The luminosity of the central star in compact HII regions was estimated from the solid angle of the nearby IR sources subtended at the central star, to be 5 ˜ 10 times as intense as that of the IR sources. The luminosity gives the stellar UV photon rate, Nu(*)(s-1), under the assumption of a single star approximation. For gas of standard dust content, Nu(*) and the observed electron density, ne, provide the dust opacity of the ionizing photons, ?Sdn, along the optical path to the Strömgren sphere of radius rs. The ionizing photon opacity over the same optical path but with the actual dust content, ?Sdi, is also derived from Nu(*) and the observed emission measure, ne2(4 ?/3)ri3, with ri of the radius of the ionized sphere. A relationship ?Nu(*)/(4 ? ri2)1/2˜= 1.3 × 109 (s-1/2m-1) with ?= ?Sdi/ ?Sdn was obtained as an observational trend for the 4 compact HII regions of NGC7538(N). Fourteen selected compact HII regions from the data catalogued by VLA observations were examined for this trend, and a similar result was shown. A confined area within 1050 >= Nu (s-1, radio) >= 1044 and 15 >= ? >= 0.1 was proposed for the location of compact HII regions in their (ne - D) diagram.

Akabane, K.; Kuno, N.

289

Ir-catalyzed reverse prenylation of 3-substituted indoles: total synthesis of (+)-aszonalenin and (-)-brevicompanine B.  

PubMed

The selective reverse prenylation of 3-substituted-1H-indoles at C3 is described. The iridium-catalyzed reaction proceeds with high branched to linear selectivity (>20:1) for a variety of indoles. In addition, a diastereoselective reverse prenylation of tryptophan methyl ester is disclosed, and its synthetic utility is demonstrated in the synthesis of (+)-aszonalenin and (-)-brevicompanine B. PMID:25365411

Ruchti, Jonathan; Carreira, Erick M

2014-12-01

290

Kinetics, stoichiometry, morphology, and current drive capabilities of Ir-based silicides  

SciTech Connect

A detailed study of the formation of iridium silicide obtained by ultrahigh vacuum annealing and atmospheric rapid thermal processing is proposed using x-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and electrical characterizations. Using XPS analysis, the stoichiometry of each silicide phase (IrSi, IrSi{sub 1.6}) is identified. A model based on the variation of the measured intensity of the Ir 4f spectra is used to obtain the kinetic coefficients of reaction of Ir silicidation (E{sub A}=2.48 eV, D{sub 0}=9 cm{sup 2}/s). TEM cross sections indicate that the roughness of the silicide/silicon interface increases with temperature. Lastly, electrical characteristics are used to identify the optimum annealing temperature to obtain an iridium silicide contact with the lowest Schottky barrier height to holes.

Larrieu, G.; Dubois, E.; Wallart, X.; Katcki, J. [Institut d'Electronique de Microelectronique et de Nanotechnologie, IEMN/ISEN UMR CNRS 8520, Avenue Poincare, Cite Scientifique, 59652 Villeneuve d'Ascq Cedex (France); Institute of Electron Technology, Al. Lotnikow 32/46, 02-668 Warsaw (Poland)

2007-11-01

291

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

PubMed Central

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

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

2014-01-01

292

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

PubMed

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

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

2014-01-01

293

Highly regioselective synthesis of N-3 organophosphorous derivatives of 3,4-dihydropyrimidin-2(1H)-ones and their calcium channel binding studies.  

PubMed

A series of novel N-3 substituted 3,4-dihydropyrimidin-2(1H)-ones derivatives bearing diaminophosphinyl, phosphonate and phosphorous containing heterocycles were obtained from 3,4-dihydropyrimidinones (DHPMs) in a regioselective manner through an efficient reaction protocol, tolerant to substitutional variation at the key diversity positions around the DHPM core. None of the representative compounds screened for calcium channel blocking activity was found to have significant activity compared to nifedipine. PMID:22703843

Singh, Kamaljit; Singh, Kawaljit; Trappanese, Danielle M; Moreland, Robert S

2012-08-01

294

Copper Nitrate Catalyzed Three-Component One-Pot Synthesis of 3,4-Dihydropyrimidin-2(1H)-Ones  

Microsoft Academic Search

An efficient synthesis of 3,4-dihydropyrimidin-2(1H)-ones from aldehydes, 1,3-dicarbonyl compounds, and urea using copper nitrate under refluxing temperature in ethanol was described. Compared with other Lewis copper salts, copper nitrate proved to be the most efficient. The advantages of the new method were good yields (61–93%), short reaction time (0.4–3 h), and inexpensive catalyst.

Min Wang; Heng Jiang; Zhiguo Song; Hong Gong

2009-01-01

295

Syntheses of 3-[(Alkylamino)methylene]-6-methylpyridine-2,4(1H,3H)-diones, 3-Substituted 7-Methyl-2H-pyrano[3,2-c]pyridine-2,5(6H)-dione Fluorescence Probes, and Tetrahydro-1H,9H-2,10-dioxa-9-azaanthracen-1-ones.  

PubMed

Various condensation and ring-closing reactions were used for the syntheses of 3-[(alkylamino)methylene]-6-methylpyri-dine-2,4(1H,3H)-diones, bicyclic pyridinones, and tricyclic morpholinopyrones. For instance, 3-[(dialkylamino)methylene]-6-methylpyridine-2,4(1H,3H)-diones were synthesized from the condensation of dialkylamines and 3-formyl-4-hydroxy-6-methylpyridin-2(1H)-one. 3-Formyl-4-hydroxy-6-methylpyridin-2(1H)-one, derived from 3-formyl-4-hydroxy-6-methylpyridin-2(1H)-one, was used to construct a number of bicyclic pyridinones via a one-pot Knoevenagal and intramolecular lactonization reaction. Tricyclic morpholinopyrones were assembled from a dialkylation reaction involving a dinucleophile, 3-amino-4-hydroxy-6-methyl-2H-pyran-2-one, and a dielectrophile, trans-3,6-dibromocyclohexene. Depending on the reaction conditions, isomers of the tricyclic molecules can be selectively produced, and their chemical structures were unequivocally determined using single-crystal X-ray analyses and 2D COSY spectroscopy. The fluorescently active bicyclic pyridinone compounds show longer absorption (368-430 nm; maximum) and emission wavelengths (450-467 nm) than those of 7-amino-4-methylcoumarin (AMC; ?abs,max = 350 nm; ?em = 430 nm) suggesting these molecules, such as 3-(2-aminoacetyl)-7-methyl-2H-pyrano[3,2-c]pyridine-2,5(6H)-dione, can be employed as fluorescence activity based probes for tracing biological pathways. PMID:25177061

Prior, Allan M; Gunaratna, Medha J; Kikuchi, Daisuke; Desper, John; Kim, Yunjeong; Chang, Kyeong-Ok; Maezawa, Izumi; Jin, Lee-Way; Hua, Duy H

2014-08-01

296

Nature of catalyst deactivation during citral hydrogenation: a catalytic and ATR-IR study  

Microsoft Academic Search

Deactivation of a 5 wt% Pd\\/Al2O3 catalyst during hydrogenation of citral (1) to citronellal (2), 3,7-dimethyl-2-octenal (3), and dihydrocitronellal (4) has been studied in a continuous-flow fixed-bed reactor. The reactions were carried out at 40?°C and 190 bar in hexane, “supercritical” CO2, or ethane as solvents. ATR-IR spectroscopic analysis of the solid\\/liquid interphase under reaction conditions at low pressure revealed

Marco Burgener; Ronny Wirz; Tamas Mallat; Alfons Baiker

2004-01-01

297

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

298

The Efficient Synthesis of 3,4-Dihydropyrimidin-2-(1H)-Ones and Their Sulfur Derivatives with H2SO4 Immobilized on Activated Charcoal  

Microsoft Academic Search

Various 3,4-dihydropyrimidin-2-(1H)-ones (DHPMs) and their sulfur derivatives were efficiently synthesized by a one-pot cyclocondensation reaction of aromatic and aliphatic aldehydes, ?-dicarbonyl compounds and urea (or thiourea) in the presence of sulfuric acid immobilized on activated charcoal (133% w\\/w). The reactions were carried out in refluxing n-hexane-acetonitrile (2.5:0.5 mL) within 5–150 min to give 3,4-dihydropyrimidinones (or thiones) in high to excellent

Karim Akbari Dilmaghani; Behzad Zeynizadeh; Hadi Parasajam

2012-01-01

299

Synthesis of new 1,5-diaryl-3-(arylamino)-1H-pyrrol-2(5H)-ones under catalyst-free and solvent-free conditions.  

PubMed

Several new 1,5-diaryl-3-(arylamino)-1H-pyrrol-2(5H)-ones were synthesized via the three-component condensation reaction of aldehydes, aromatic amines, and ethyl pyruvate under catalyst-free and solvent-free conditions. Also, 5-(4-hydroxyl-3-nitrophenyl)-1-(4-methoxy-phenyl)-3-(4-methoxyphenylamino)-1,5-dihydro-pyrrol-2-one was synthesized using oxime instead of aldehyde. The eco-friendly, simple procedure, green procedure, catalyst-free and solvent-free conditions, short reaction times, and high yields of the products are the advantages of this method. PMID:24357192

Niknam, Khodabakhsh; Mojikhalifeh, Sanaz

2014-02-01

300

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

301

Analyzing power formula and application to low energy nuclear reactions  

Microsoft Academic Search

General formulas of analyzing powers in nuclear reactions are derived in a model-independent way, decomposing the analyzing powers by the rank of tensors in the spin space by the invariant-amplitude method. The validity of the formulas is examined in low energy reactions, the 3He(d-->,p)4He reaction at the 430-keV resonance and 1H(d-->,gamma)3He reactions at energies below 80 keV, for which the

M. Tanifuji; H. Kameyama

1999-01-01

302

Atmospheric Entry Experiments at IRS  

NASA Astrophysics Data System (ADS)

Entering the atmosphere of celestial bodies, spacecrafts encounter gases at velocities of several km/s, thereby being subjected to great heat loads. The thermal protection systems and the environment (plasma) have to be investigated by means of computational and ground facility based simulations. For more than a decade, plasma wind tunnels at IRS have been used for the investigation of TPS materials. Nevertheless, ground tests and computer simulations cannot re- place space flights completely. Particularly, entry mission phases encounter challenging problems, such as hypersonic aerothermodynamics. Concerning the TPS, radiation-cooled materials used for reuseable spacecrafts and ablator tech- nologies are of importance. Besides the mentioned technologies, there is the goal to manage guidance navigation, con- trol, landing technology and inflatable technologies such as ballutes that aim to keep vehicles in the atmosphere without landing. The requirement to save mass and energy for planned interplanetary missions such as Mars Society Balloon Mission, Mars Sample Return Mission, Mars Express or Venus Sample Return mission led to the need for manoeuvres like aerocapture, aero-breaking and hyperbolic entries. All three are characterized by very high kinetic vehicle energies to be dissipated by the manoeuvre. In this field flight data are rare. The importance of these manoeuvres and the need to increase the knowledge of required TPS designs and behavior during such mission phases point out the need of flight experiments. As result of the experience within the plasma diagnostic tool development and the plasma wind tunnel data base, flight experiments like the PYrometric RE-entry EXperiment PYREX were developed, fully qualified and successfully flown. Flight experiments such as the entry spectrometer RESPECT and PYREX on HOPE-X are in the conceptual phase. To increase knowledge in the scope of atmospheric manoeuvres and entries, data bases have to be created combining both 3-D calculations and obtained flight data. Experience in this field and flight data are rare. But there are data bases in the USA, where public access is often difficult. The data mostly deal with reuseable launch vehi- cle technology which is a concern for the understanding of entry missions to earth and for the aim to reduce payload transportation costs in future. For X-38 about 40 international partners have been collaborating to develop, qualify and fly X-38 which is a technology demonstrator for the Crew Return Vehicle (CRV) of the International Space Station (ISS). About 1000 sensors will be operated to obtain a data base which will be combined with a aerothermodynamic data base (European contribution). Additionally, a lot of instrumentation has been contributed. PYREX-KAT38 meas- uring the temperature distribution in the X-38 nose structure was developed by IRS. The data of the PYREX sensor system contribute to several fields of interest i.e. temperature histories at 5 positons in the nose structure, information about rotational degrees of freedom of the vehicle during entry, statements on the behavior of the TPS material and heat flux distribution. The paper presents experiments that are being developed at IRS. Below summaries of such experi- ments are given: PYREX is a pyrometric entry experiment measuring rear side temperatures of ceramic TPS. It has already been flown twice. The first flight was with the German-Japanese capsule EXPRESS, the second with the capsule MIRKA. PY- REX-KAT38 was delivered to NASA. It is a fully qualified temperature measurement system and will be operated aboard the X-38 vehicle. RESPECT is a spectrometer that will be used to gain spectral data in the flow field around a space vehicle. The main goal is to obtain information about the plasma state in the post shock regime of a vehicle by measuring the spectrally resolved radiation. The obtained database will provide radiation of multiple species for a comparison with computer simulations. PHLUX: Based on experiences with PYREX, a sensor for heat flux measurements is being de

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

2002-01-01

303

Morphological Typology of Languages for IR.  

ERIC Educational Resources Information Center

Presents a morphological classification of languages from the information retrieval (IR) perspective. Discusses differences in inflection, derivation, and compounding; index of synthesis and index of fusion; cross-language retrieval research; the need for semantic and syntactic typologies; and the effects of morphology and stemming in IR.…

Pirkola, Ari

2001-01-01

304

On the integration of IR and Databases  

Microsoft Academic Search

Integration of information retrieval (IR) in database management systems (DBMSs) has proven difficult. Previous attempts to integration suffered from inherent performance problems, or lacked desirable separation between logical and physical data models. To overcome these problems, we discuss a database approach based on structural object-orientation. We implement IR techniques using extensions in an object algebra called MOA. MOA has been

Arjen P. de Vries; Annita N. Wilschut

1999-01-01

305

Optimum Database Selection in Networked IR  

Microsoft Academic Search

this paper, we make an attempt to apply these ideas to the problem of database selectionin networked IR. The basic setting is as follows: A broker has access to a set of IR databasesto which it may send a query. In response, each database produces a ranked list of documents,and the broker may request any number of documents from this

Norbert Fuhr

1996-01-01

306

Workshop on Commercial Application of IR Spectroscopies  

E-print Network

Workshop on Commercial Application of IR Spectroscopies to Solid Wood Philip J. Harris and Clemens SPECTROSCOPIES TO SOLID WOOD PHILIP J. HARRIS AND CLEMENS M. ALTANER (EDS) WOOD TECHNOLOGY RESEARCH CENTRE WORKSHOP PROCEEDINGS 2013 #12;ii PREFACE The workshop "Commercial Application of IR Spectroscopies to Solid

Hickman, Mark

307

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

308

Testing a model of IR radiative losses  

NASA Astrophysics Data System (ADS)

Thermopile pyranometers exhibit IR radiative losses that affect global and diffuse shortwave measurements made with first class thermopile based instruments. Pyrgeometers can be used to measure the sky temperature and are used to calculate the pyranometer's IR radiative losses. Few solar monitoring sites are equipped with pyrgeometers necessary to account for the IR radiative losses associated with the pyranometers. High quality data from the Solar Radiation Research Laboratory (SRRL) at the National Renewable Energy Laboratory are used to test and further develop a model for the IR radiative losses without the use of pyrgeometer data. The various methods for obtaining IR radiative loss values are compared and contrasted using the SRRL data. A simple scaling method is proposed and tested to adjust the non-pyrgeometer based correlation models to sites with different sky temperature characteristics.

Vignola, Frank; Long, Charles N.; Reda, Ibrahim

2009-08-01

309

Reversible Reactions  

NSDL National Science Digital Library

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

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

2005-09-01

310

Enzyme Reactions  

NSDL National Science Digital Library

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

School, Minerva D.

2011-10-03

311

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

312

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

313

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

314

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

315

Reactions of alkyne- and butadiyne-derived fluorinated cyclophosphazenes with diiron and dimolybdenum carbonyls.  

PubMed

The reaction of (?-phenylethynyl)pentafluorocyclotriphosphazene, [(PhC?C)(F)PN](PNF2)2, with Fe2(CO)9 in refluxing hexane resulted in five new compounds, namely, [Fe(CO)2{?(2):?(2)-2,4-(P3N3F5)2Ph2C4Fe(CO)3}-?-CO] (1), [Fe(CO)2{?(2):?(2)-2,5-(P3N3F5)2Ph2C4Fe(CO)3}-?-CO] (2), [Fe(CO)2{?(5)-2,5-(P3N3F5)2Ph2C4CO}C(Ph)?C(P3N3F5)](3), [Fe(CO)3{?(2):?(2)-2,4-(P3N3F5)2Ph2C4CO] (4), and [Fe(CO)3{?(2):?(2)-2,5-(P3N3F5)2Ph2C4CO] (5). While compounds 1, 2, 4, and 5 have five-membered ferracyclopentadiene or cyclopentadienone rings coordinated to the Fe(CO)3 unit in the ?(2):?(2) mode, compound 3 has a 2,5-cyclopentadienone ring attached to an Fe(CO)2(P3N3F5)C?C(Ph) unit, where Fe is ?(5)-bonded to the cyclopentadienone ring, and the carbon that is ? to the phenyl unit of the Fe(CO)2(P3N3F5)C?C(Ph) group is ?-bonded to the oxygen atom of the cyclopentadienone ring. Formation of five-membered cyclic compounds having two fluorophosphazene units on the vicinal carbon atoms of C4R2R'2Y rings was not observed in this reaction. No examples of Fe(CO)3-bound cyclobutadiene complexes were also isolated from this reaction. A similar reaction in the presence of trimethylamine N-oxide, NMe3O, was found to proceed at -20 °C with the formation of compounds 4 and 5 only. In contrast to the Fe2(CO)9 reaction, a reaction of alkyne-derived pentafluorocyclotriphosphazenes, [(RC?C)(F)PN](PNF2)2 [R = Ph, Fe(C5H5)2] with the molybdenum complex Cp(CO)3Mo-Mo(CO)3Cp (Cp = cyclopentadienyl) in refluxing toluene resulted in the simple tetrahedral clusters Cp(CO)2Mo(P3N3F5)C-C(Ph)Mo(CO)2Cp (6) and Cp(CO)2Mo(P3N3F5)C-C(Fc)Mo(CO)2Cp (7) (Fc = ferrocenyl). A similar reaction of Cp(CO)3Mo-Mo(CO)3Cp with butadiyne-derived fluorophosphazenes, [(RC?C-C?C)(F)PN](PNF2)2 [R = Ph, Fe(C5H5)2], yielded the tetrahedral clusters Cp(CO)2Mo(P3N3F5)C-C(C?CPh)Mo(CO)2Cp (8) and Cp(CO)2Mo(P3N3F5)C-C(C?CFc)Mo(CO)2Cp (9) with the tetrahedral Mo2C2 unit forming exclusively with the alkyne unit of the butadiyne group bound to the cyclophosphazene ring. The crystal structures and infrared spectral data of these molybdenum clusters showed the presence of a semibridging carbonyl on one of the molybdenum units. All new compounds were characterized by IR, NMR [(1)H, (13)C{(1)H}, (31)P{(1)H}, and (19)F{(1)H}] and high-resolution mass spectrometry studies. Compounds 2, 3, 5, and 7-9 were also structurally characterized using single-crystal X-ray diffraction studies. PMID:25211189

Kumar, Dheeraj; Singh, Nem; Elias, Anil J; Malik, Pauline; Allen, Christopher W

2014-10-01

316

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

317

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

318

Neuroprotective effects of Huang-Lian-Jie-Du-Decoction on ischemic stroke rats revealed by (1)H NMR metabolomics approach.  

PubMed

Huang-Lian-Jie-Du-Decoction (HLJDD) is a representative antipyretic and detoxifying recipe in traditional Chinese medicine (TCM). This formula and its component herbs like Radix Scutellariae, Fructus Gardeniae show a variety of neuroprotective activities and have been used for the treatment of nervous system diseases including stroke. To comprehensively and holistically assess its therapeutic effect on ischemic stroke, a novel integrative metabolomics approach was applied. A rat ischemic stroke model was established by introduction of transient middle cerebral artery occlusion (MCAO) followed by reperfusion. The neurological deficit, cerebral infarct size and morphological abnormality were evaluated. An NMR technique combined with appropriate statistical analyses was then performed to explore the metabonomic profiles of serum and brain tissue extracts. Pattern analysis of the (1)H NMR data disclosed that HLJDD could relieve stroke rats suffering from the ischemia/reperfusion (I/R) injury by ameliorating the disturbance in energy metabolism, membrane and mitochondrial metabolism, neurotransmitter and amino acid metabolism, alleviating the oxidative stress from reactive oxygen species (ROS) and the inflammatory damage, and recovering the destructed osmoregulation. PMID:24051274

Wang, Peng-Ran; Wang, Jun-Song; Yang, Ming-Hua; Kong, Ling-Yi

2014-01-01

319

PREMIER's imaging IR limb sounder  

NASA Astrophysics Data System (ADS)

The Imaging IR Limb Sounder (IRLS) is one of the two instruments planned on board of the candidate Earth Explorer Core Mission PREMIER. PREMIER stands for PRocess Exploration through Measurements of Infrared and Millimetrewave Emitted Radiation and is presently under feasibility study by ESA. Emerging from recent enhanced detector and processing technologies IRLS shall, next to a millimetre-wave limb sounder, explore the benefits of three-dimensional limb sounding with embedded cloud imaging capability. Such 3d imaging technology is expected to open a new era of limb sounding that will allow detailed studies of the link between atmospheric composition and climate, since it will map simultaneously fields of temperature and many trace gases in the mid/upper troposphere and stratosphere across a large vertical and horizontal field of view and with relatively high vertical and horizontal resolution. PREMIER shall fly in tandem formation looking backwards to METOP's swath and thereby explore the benefit of 3-dimensional information for meteorological/environmental analyses and climate forcing investigations. As currently planned and if implemented, IRLS will cover a total horizontal field of about 360 km and observe the limb at altitudes between 4 and 52 km. The vertical spatial sampling distance (SSD) will be well below 1 km. It will be run in two different exclusive modes to address scientific questions about atmospheric dynamics and chemistry at spectral samplings of ~1.2 cm-1 and ~0.2 cm-1, respectively. In such configuration IRLS will be composed of an imaging array with about 1800 macro pixels or sub-samples, thereby allowing cloud imaging and rejection at sufficient spatial resolution. We will present an overview of the instrument requirements as derived from the scientific requirements, the present status of the mission, and we will give an overview of the currently identified technology needs and instrument predevelopments.

Kraft, Stefan; Caron, Jerome; Bézy, Jean-Loup; Meynart, Roland; Langen, Jörg; Carnicero Dominguez, Bernardo; Bensi, Paolo; Silvestrin, Pierluigi

2011-11-01

320

Synthetic IR Cloud Image Model  

NASA Astrophysics Data System (ADS)

The presence of clouds affects most infrared (IR) military sensors. Foreground clouds degrade or occult target signatures and background clouds clutter a scene. Models used to assess or predict system performance must include important features of clouds: absorption, single and multiple scattering, thermal emission, partial transmission and spatial non-uniformity. Exact models which account for the details of cloud microphysics require large computation times and inputs which are difficult to obtain. Aerodyne has developed an approximate model which produces realistic cloud scenes in a reasonable amount of computer time. An average optical depth for the cloud is first calculated by use of LOWTRAN6 with specified aerosol optical properties. These properties are combined with a multiple scattering model which uses a two stream approximation. This model assumes that 1) the cloud layer is a parallel plane and infinite, 2) there is a constant single scattering albedo which may be wavelength dependent, 3) there is local thermodynamic equilibrium between particles and atmospheric gases, and 4) there is a uniform cloud temperature and emissivity. The result is an average cloud radiance spectrum along a specified line-of-sight. The line-of-sight may be up-looking or down-looking, and up to two cloud layers may be present. Spatial non-uniformities are incorporated by use of a cloud texture model based on a 1/f spectral shaping of spatial variations. The final scene including the effect of the atmospheric path from the cloud to the observer is in-band integrated and recorded as a grid of radiances with an associated depth map for use in a target/background interface model.

Conant, J.; Dvore, D.; Gruninger, J.

1988-08-01

321

1-Methyl-3-(2-oxo-2H-chromen-3-yl)-1H-imidazol-3-ium picrate  

PubMed Central

The title salt, C13H11N2O2 +·C6H2N3O7 ?, is the unexpected product of a domino reaction of 3-cyano­methyl-1-methyl­imidazolium chloride with salicylic aldehyde in the presence of picric acid. In the cation, the 1H-imidazole ring is twisted by 63.2?(1)° from the 2H-chromen plane. In the crystal, cations and anions are alternately stacked along the a axis through ?–? stacking inter­actions between the almost parallel aromatic rings [centroid–centroid distances = 3.458?(2) and 3.678?(2)?Å]. The stacks are further linked by C—H?O hydrogen bonds into a two-tier layer parallel to (001). PMID:23795027

Tuyen, Nguyen Van; Anh, Le Tuan; Festa, Alexey A.; Voskressensky, Leonid G.; Khrustalev, Victor N.

2013-01-01

322

Heterohelicenes with embedded P-chiral 1H-phosphindole or dibenzophosphole units: diastereoselective photochemical synthesis and structural characterization.  

PubMed

The oxidative photocyclization reactions of olefins that contain 1H-phosphindole or dibenzophosphole substituents have been applied to the synthesis of P/N-bi-heterosubstituted dimeric helicenes, as well as of new [6]- and [8]phosphahelicenes. In these photocyclization processes, the configuration of the stereogenic phosphorus center dictates the sense of helical chirality. Thus, by starting from enantiomerically pure P-menthylphosphole-oxide units, this method affords enantiopure helical compounds. The helical phosphine oxides were characterized by X-ray diffraction. After reduction of the phosphine-oxides, the corresponding helical phosphines have been used as ligands in transition-metal complexes. The X-ray crystal structure of a gold chloride complex of a [6]helicene is reported. PMID:23766244

Yavari, Keihann; Retailleau, Pascal; Voituriez, Arnaud; Marinetti, Angela

2013-07-22

323

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.

Cremonini, Sera; Rong, Junchen; Sun, Kai

2014-01-01

324

Regioselective synthesis of novel 4,5-diaryl functionalized 3,4-dihydropyrimidine-2(1H)-thiones via a non-Biginelli-type approach and evaluation of their in vitro anticancer activity.  

PubMed

An easy and novel approach to synthesize 4,5-diaryl functionalized 3,4-dihydropyrimidine-2(1H)-thiones via addition of aryllithiums to 5-aryl substituted pyrimidine-2(1H)-thiones, which could be regarded as a method complementary to the most widely used Biginelli-type synthesis, is described. In the reaction of aryllithiums with N-(Me)Bn substituted pyrimidine-2(1H)-thiones a high degree of regioselectivity of addition, leading to 4-aryl adducts, was achieved. Selected compounds tested for their in vitro anticancer activity against four human cancer cell lines showed the greatest activity against breast cancer (MCF7). 1-Benzyl-4-(3-hydroxyphenyl)-5-phenyl substituted 3,4-dihydropyrimidine-2(1H)-thione (10g) exhibiting 10-fold more potent activity than the best known monastrol (MON) stands as a promising candidate for further scaffold and asymmetric synthesis. PMID:24752551

So?nicki, Jacek G; Struk, ?ukasz; Kurzawski, Mateusz; Peru?y?ska, Magdalena; Maciejewska, Gabriela; Dro?dzik, Marek

2014-06-01

325

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

326

New proton radioactivities 165,166,167Ir and 171Au  

NASA Astrophysics Data System (ADS)

The new proton radioactivities 165,166,167Ir and 171Au have been observed. The Ir isotopes were produced via the 92Mo(78Kr,pxn)165,166,167Ir reactions at 357 and 384 MeV. 171Au was produced via the 96Ru(78Kr,p2n)171Au reaction at 389 MeV. The proton emitters were each identified by position, time, and energy correlations between the implantation of a residual nucleus into a double-sided silicon strip detector, the observation of a decay proton, and the subsequent observation of a decay alpha particle from the daughter nucleus (164,165,166Os and 170Pt, respectively). Both 166Ir and 167Ir have proton-emitting ground and isomeric states, which also decay by alpha emission. The proton-decay rates have been reproduced by calculations using the WKB barrier penetration approximation and a low-seniority shell-model calculation of the spectroscopic factors. The alpha decays of the four nuclei are followed by chains of alpha decays, allowing the determination of single-particle orbital orderings. Mass information has also been obtained from the alpha-decay chains because a connection to a known mass can be obtained for one of the nuclei. Ground-state mass excesses are reported for 151Tm, 154Yb, 155Lu, 158Hf, 159Ta, 162W, 163Re, 166Os, 167Ir, and 170Pt. The mass excess for 171mAu is also given. Proton separation energies are also deduced for the odd-Z alpha daughter nuclei of the Ir proton emitters.

Davids, C. N.; Woods, P. J.; Batchelder, J. C.; Bingham, C. R.; Blumenthal, D. J.; Brown, L. T.; Busse, B. C.; Conticchio, L. F.; Davinson, T.; Freeman, S. J.; Henderson, D. J.; Irvine, R. J.; Page, R. D.; Penttilä, H. T.; Seweryniak, D.; Toth, K. S.; Walters, W. B.; Zimmerman, B. E.

1997-05-01

327

Antidepressants induce cellular insulin resistance by activation of IRS-1 kinases.  

PubMed

Certain selective serotonin reuptake inhibitors (SSRIs) induce the clinical and biochemical manifestations of a metabolic syndrome by as yet unknown mechanism. Here we demonstrate that incubation (1 h) of rat hepatoma Fao cells with the SSRIs paroxetine and sertraline, but not with the atypical antipsychotic drug olanzapine, inhibited the insulin-stimulated Tyr phosphorylation of the insulin receptor substrate-1 (IRS-1) with half-maximal effects at approximately 10 microM. This inhibition correlated with a rapid phosphorylation and activation of a number of Ser/Thr IRS-1 kinases including JNK, S6K1, ERK and p38 MAPK, but not PKB (Akt). JNK appears as a key player activated by SSRIs because specific JNK inhibitors partially eliminated the effects of these drugs. The SSRIs induced the phosphorylation of IRS-1 on S307 and S408, which inhibits IRS-1 function and insulin signaling. These results implicate selected SSRIs as inhibitors of insulin signaling and as potential inducers of cellular insulin resistance. PMID:17728140

Levkovitz, Yechiel; Ben-Shushan, Galit; Hershkovitz, Avia; Isaac, Roi; Gil-Ad, Irit; Shvartsman, Dima; Ronen, Denise; Weizman, Abraham; Zick, Yehiel

2007-11-01

328

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

PubMed

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

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

2014-10-01

329

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

330

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

331

Synthesis and Cytotoxicity Evaluation of Some Novel Thiazoles, Thiadiazoles, and Pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-5(1H)-ones Incorporating Triazole Moiety.  

PubMed

Reactions of hydrazonoyl halides and each of methyl 2-(1-(5-methyl-1-phenyl-1H-1,2,3-triazol-4-yl)ethylidene)hydrazine-1-carbodithioate and 2-(1-(5-methyl-1-phenyl-1H-1,2,3-triazol-4-yl)ethylidene)hydrazine-1-carbothioamide afforded 2-(1-(5-methyl-1-phenyl-1H-1,2,3-triazol-4-yl)ethylidene)hydrazono)-3-phenyl-5-substituted-2,3-dihydro-1,3,4-thiadiazoles and 5-(4-substituted)diazenyl)-2-(2-(1-(5-methyl-1-phenyl-1H-1,2,3-triazol-4-yl)ethylidene)hydrazinyl)-4-arylthiazoles, respectively. Analogously, the reactions of hydrazonoyl halides with 7-(5-methyl-1-phenyl-1H-1,2,3-triazol-4-yl)-5-phenyl-2-thioxo-2,3-dihydropyrido[2,3-d]pyrimidin-4(1H)-one gave 3-(4-substituted)-8-(5-methyl-1-phenyl-1H-1,2,3-triazol-4-yl)-6-phenyl-1-arylpyrido[2,3-d]-[1,2,4]-triazolo-[4,3-a]pyrimidin- 5(1H)-ones in a good yield. The structures of the newly synthesized were elucidated via elemental analysis, spectral data and alternative synthesis routes whenever possible. Twelve of the newly synthesized compounds have been evaluated for their antitumor activity against human breast carcinoma (MCF-7) and human hepatocellular carcinoma (HepG2) cell lines. Their structure activity relationships (SAR) were also studied. The 1,3,4-thiadiazole derivative 9b (IC50 = 2.94 µM) has promising antitumor activity against the human hepatocellular carcinoma cell line and the thiazole derivative 12a has promising inhibitory activity against both the human hepatocellular carcinoma cell line and the breast carcinoma cell line (IC50 = 1.19, and 3.4 µM, respectively). PMID:25594346

Gomha, Sobhi M; Ahmed, Sayed A; Abdelhamid, Abdou O

2014-01-01

332

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

PubMed

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

Liu, Xianghao; Braunstein, Pierre

2013-07-01

333

Cr(3+)-Doped Lanthanum Gallogermanate Phosphors with Long Persistent IR Emission  

SciTech Connect

Lanthanum gallogermanate co-doped with chromium (La3Ga5GeO14:Cr3+,M, where M=Li, Pb2+, Zn2+, Eu3+, Tm3+, and Dy3+) samples have been prepared using a solid-state chemical reaction method. The phosphor with Dy3+ is observed to have a persistent IR emission for more than 8 h, which is recorded using a spectrometer. The wavelength of the major IR emission is in the range from 700 to 1100 nm. The intensity of the phosphorescence and persistent time can be modified by co-doping proper trapping centers.

Jia, George D [ORNL; Lewis, Linda A [ORNL; Wang, Xiao-jun [Georgia Southern University

2010-01-01

334

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

335

Combined 1H-NMR and 1H-13C HSQC-NMR to improve urinary screening in autism spectrum disorders.  

PubMed

Autism spectrum disorders (ASD) are neurodevelopmental diseases with complex genetic and environmental etiological factors. Although genetic causes play a significant part in the etiology of ASD, metabolic disturbances may also play a causal role or modulate the clinical features of ASD. The number of ASD studies involving metabolomics is increasing, and sometime with conflicting findings. We assessed the metabolomics profiling of urine samples to determine a comprehensive biochemical signature of ASD. Furthermore, to date no study has combined metabolic profiles obtained from different analytical techniques to distinguish patient with ASD from healthy individuals. We obtained (1)H-NMR spectra and 2D (1)H-(13)C HSQC NMR spectra from urine samples of patients with ASD or healthy controls. We analyzed these spectra by multivariate statistical data analysis. The OPLS-DA model obtained from (1)H NMR spectra showed a good discrimination between ASD samples and non-ASD samples (R(2)Y(cum) = 0.70 and Q(2) = 0.51). Combining the (1)H NMR spectra and the 2D (1)H-(13)C HSQC NMR spectra increased the overall quality and predictive value of the OPLS-DA model (R(2)Y(cum) = 0.84 and Q(2) = 0.71), leading to a better sensitivity and specificity. Urinary excretion of succinate, glutamate and 3-methyl-histidine differed significantly between ASD and non-ASD samples. Urinary screening of children with neurodevelopmental disorders by combining NMR spectroscopies (1D and 2D) in multivariate analysis is a better sensitive and a straightforward method that could help the diagnosis ASD. PMID:24841505

Nadal-Desbarats, Lydie; Aïdoud, Nacima; Emond, Patrick; Blasco, Hélène; Filipiak, Isabelle; Sarda, Pierre; Bonnet-Brilhault, Frédérique; Mavel, Sylvie; Andres, Christian R

2014-07-01

336

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

337

Pilietinis nepaklusnumas ir demokratija: socioedukacin? dimensija.  

E-print Network

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

Butkevi?ius,; Audrius

2012-01-01

338

Probabilistic detection and tracking of IR targets  

NASA Astrophysics Data System (ADS)

The problem of automatic target recognition (ATR) and image classification have been active research fields in image processing. In this research, we explore ATR techniques such as object pre-processing, detection, tracking and classification for sequence of infrared (IR) images. The detection and tracking of IR images is performed using Bayesian probabilistic technique. The tracked part of the object frame is then processed to discard the background to obtain just the segmented object. The segmented dataset is then rendered shift invariant by first calculating the mean of the object and then moving the mean to center of the frame. We divide each frame into blocks and obtain statistical features such as mean, variance, minimum and maximum intensity in each block for subsequent classification. We visually divide entire IR dataset into 8 classes for supervised training using a K-nearest neighbor classifier. We classify the test IR dataset into 8 different classes successfully.

Shaik, Jahangheer S.; Iftekharuddin, Khan M.

2004-11-01

339

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

340

Mid-IR supercontinuum generation and applications: a review  

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

341

Hypersensitivity reactions to beta-lactams.  

PubMed

Beta-lactam antibiotics (BLs) are the most frequent cause of hypersensitivity reactions mediated by specific immunological mechanisms, with two main types, IgE reactions or T-cell-dependent responses. From a practical point of view, these reactions can be classified into immediate, for those appearing within 1 h after drug intake, and non-immediate, for those appearing at least 1 h after and usually within 24 h of BL administration. The clinical symptoms differ according to this classification. Urticaria and anaphylaxis are the most frequently recorded symptoms in immediate reactions and maculopapular exanthema and delayed urticaria in non-immediate reactions. Although the exact diagnostic approach differs depending on the underlying mechanism, it is based on the performance of skin testing, laboratory tests, and drug provocation tests.T cells are a key factor in all types of hypersensitivity reactions to BLs, regulating both IgE production or acting as effector cells, with a different profile of cytokine production. A Th1 pattern is observed in both CD4(+) and CD8(+) peripheral T cells in non-immediate reactions, whereas a Th2 pattern is expressed in CD4(+) T cells in immediate reactions. PMID:24214624

Torres, Maria J; Mayorga, Cristobalina; Blanca-López, Natalia; Blanca, Miguel

2014-01-01

342

Xanthan Sulfuric Acid: An Efficient Bio-Supported and Recyclable Solid Acid Catalyst for the Synthesis of 4,4-(Arylmethylene)bis(1 h-Pyrazol-5-ols)  

Microsoft Academic Search

A simple and efficient method has been developed for the synthesis of 4,4-(arylmethylene)bis(1H-pyrazol-5-ols) by the condensation reaction between substituted aldehydes, and 1-phenyl-3-methylpyrazol-5-one in the presence of Xanthan sulfuric acid (XSA) as a solid acid catalyst. This method is simple, cost effective, requires short reaction times, yields are excellent with high purity and the catalyst could be easily recycled.

B. Suresh Kuarm; B. Rajitha

2012-01-01

343

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

344

Earth's Atmospheric CO2 Saturated IR Absorption  

Microsoft Academic Search

Using the on-line SpectraCalc IR absorption simulator, the amount of IR absorption by the 15 mu line of the current atmospheric CO2 was obtained and compared with that of twice the amount of CO2. The simulation required a fixed density equivalent for the atmospheric path length. This was obtained by numerically integrating the NOAA Standard Atmospheric model. While the current

Ernst Wall

2008-01-01

345

CUPID: Customizable User Pipeline for IRS Data  

NASA Astrophysics Data System (ADS)

Written in c, the Customizable User Pipeline for IRS Data (CUPID) allows users to run the Spitzer IRS Pipelines to re-create Basic Calibrated Data and extract calibrated spectra from the archived raw files. CUPID provides full access to all the parameters of the BCD, COADD, BKSUB, BKSUBX, and COADDX pipelines, as well as the opportunity for users to provide their own calibration files (e.g., flats or darks). CUPID is available for Mac, Linux, and Solaris operating systems.

Spitzer Science User Support Team; Spitzer Science Instrument Team; IRSA Science User Support Team

2013-11-01

346

QWIP and 3rd generation IR imagers  

Microsoft Academic Search

Standard GaAs\\/AlGaAs Quantum Well Infrared Photodetectors (QWIPs) are from now seriously considered for the 3rd generation of IR imagers. Since 2002, the THALES Group has been manufacturing sensitive arrays using QWIP technology based on AsGa techniques through THALES Research and Technology Laboratory. This QWIP technology allows the realization of large staring arrays for Thermal Imagers (TI) working in the IR

E. Costard; Ph. Bois; X. Marcadet; A. Nedelcu

2005-01-01

347

Synthesis of 3,4?Dihydropyrimidine?2(1H)?thiones and Quinazolin?4(3H)?ones over Yb(III)?Resin Catalyst Under Solvent?free Conditions  

Microsoft Academic Search

Ytterbium(III) reagent supported on ion exchange resin is applied to the multicomponent condensation reactions under solvent?free conditions. One?pot synthesis of a library of 3,4?dihydropyrimidine?2(1H)?thiones and quinazolin?4(3H)?ones were described. The advantages of easy separation and recyclability of the catalysts were demonstrated.

Zhidong Jiang; Ruifang Chen

2005-01-01

348

Melamine trisulfonic acid: A new, efficient and recyclable catalyst for the synthesis of 3,4-dihydropyrimidin-2(1 H)-ones\\/thiones in the absence of solvent  

Microsoft Academic Search

Melamine trisulfonic acid (MTSA) can be used as an efficient and recyclable catalyst for the promotion of the synthesis of 3,4-dihydropyrimidin-2(1H)-ones\\/thiones (DHPMs) in the absence of solvent. All reactions were performed at 80°C in good to high yields.

Farhad Shirini; Mohammad Ali Zolfigol; Jalal Albadi

2011-01-01

349

A Green, Expeditious, One-Pot Synthesis of 3, 4-Dihydropyrimidin-2(1H)-ones Using a Mixture of Phosphorus Pentoxide-Methanesulfonic Acid at Ambient Temperature  

PubMed Central

An expeditious, one-pot method for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones using a mixture of phosphorus pentoxide-methanesulfonic acid (Eaton's reagent) at room temperature under solvent-free conditions is described. The salient features of this method include short reaction time, green aspects, high yields, and simple procedure. PMID:24052843

Borse, Amulrao; Patil, Mahesh; Patil, Nilesh; Shinde, Rohan

2012-01-01

350

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

SciTech Connect

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

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

1989-08-01

351

Linewidths in bound state resonances for helium scattering from Si(111)-(1 × 1)H  

Microsoft Academic Search

Helium-3 spin-echo measurements of resonant scattering from the Si(111)-(1 × 1)H surface, in the energy range 4-14 meV, are presented. The measurements have high energy resolution yet they reveal bound state resonance features with uniformly broad linewidths. We show that exact quantum mechanical calculations of the elastic scattering, using the existing potential for the helium\\/Si(111)-(1 × 1)H interaction, cannot reproduce

F. E. Tuddenham; H. Hedgeland; J. Knowling; A. P. Jardine; D. A. MacLaren; G. Alexandrowicz; J. Ellis; W. Allison

2009-01-01

352

Facile measurement of 1 H– 15 N residual dipolar couplings in larger perdeuterated proteins  

Microsoft Academic Search

We present a simple method, ARTSY, for extracting 1JNH couplings and 1H–15N RDCs from an interleaved set of two-dimensional 1H–15N TROSY-HSQC spectra, based on the principle of quantitative J correlation. The primary advantage of the ARTSY method over\\u000a other methods is the ability to measure couplings without scaling peak positions or altering the narrow line widths characteristic\\u000a of TROSY spectra.

Nicholas C. Fitzkee; Ad Bax

2010-01-01

353

Multisection 1 H Magnetic Resonance Spectroscopic Imaging Assessment of Glioma Response to Chemotherapy  

Microsoft Academic Search

Summary  This study evaluated the role of proton magnetic resonance spectroscopic imaging (1H MRSI) in assessing the response of low-grade brain tumors to a chemotherapy-only treatment regimen. Specifically, it was\\u000a of interest to assess if 1H MRSI could detect early tumor response to therapy prior to magnetic resonance imaging (MRI) changes, and to establish which\\u000a spectral markers were sensitive to regional

Casilda Balmaceda; Dana Critchell; Xiangling Mao; Kenneth Cheung; Susan Pannullo; Robert L. DeLaPaz; Dikoma C. Shungu

2006-01-01

354

Reaction Time  

NSDL National Science Digital Library

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

Science, New Y.

1999-01-01

355

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

356

Antimycobacterial evaluation of novel [4,5-dihydro-1H-pyrazole-1-carbonyl]pyridine derivatives synthesized by microwave-mediated Michael addition.  

PubMed

The focus of this study is the synthesis and biological activity evaluation of a series of dibenzalaceton derivatives (3a-3n) and novel [4,5-dihydro-1H-pyrazole-1-carbonyl]pyridine derivatives (5a-5g) against Mycobacterium bovis, Bacillus Calmette-Guerin (BCG). Dibenzalacetone derivatives were synthesized by benzaldehyde derivatives. The [4,5-dihydro-1H-pyrazole-1-carbonyl]pyridine derivatives were synthesized by Michael addition reaction and using green chemistry microwave-mediated method. All compounds were evaluated against BCG and the activity expressed as minimum inhibitory concentration (MIC) in ?M. The result showed good activity for all the compounds especially compounds (3a), (3n), and (5a) illustrated high activity (7.03, 8.10 and 5.37??M, respectively). Copyright © 2014 John Wiley & Sons, Ltd. PMID:25219796

Sedighi, Vida; Azerang, Parisa; Sardari, Soroush

2014-09-14

357

1H NMR for quantifying sulfide trapping efficiency by using 1,3,5-tris(2-hydroxyethyl)-1,3,5-triazinane.  

PubMed

Hydrogen sulfide (H2S) is an extremely toxic colourless gas; it is corrosive and denser than air. It usually happens in oil and natural gas fields, refineries, coal mines, and in some industrial effluent treatment systems. This work presents an alternative method of monitoring and quantifying H2S trapping efficiency by using 1,3,5-tris(2-hydroxyethyl)-1,3,5-triazinane as a sequestering agent, and sodium sulfide as a source of sulfide ion, through (1)H NMR spectroscopy. The results proved that the reaction occurs very quickly at 20?°C at pH 7 and 10. 3,5-di(2-hydroxyethyl)-1,3,5-thiodiazinane and 5-(2-hydroxyethyl)-1,3,5-dithiozinane were observed and quantified; it was evidenced that (1)H NMR spectroscopy can be applied as a fast and effective method to quantify H2S trapping efficiency. PMID:24723368

Canuto, André V S; Echevarria, Aurea

2014-07-01

358

1H and 13C hyperfine coupling constants of the tryptophanyl cation radical in aqueous solution from microsecond time-resolved CIDNP.  

PubMed

Relative values of the 1H and 13C isotropic hyperfine couplings in the cationic oxidized tryptophan radical TrpH*+ in aqueous solution are determined. The data are obtained from the photo-CIDNP (chemically induced dynamic nuclear polarization) enhancements observed in the microsecond time-resolved NMR spectra of the diamagnetic products of photochemical reactions in which TrpH*+ is a transient intermediate. The method is validated using the tyrosyl neutral radical Tyr*, whose 1H and 13C hyperfine couplings have previously been determined by electron paramagnetic resonance spectroscopy. Good agreement is found with hyperfine coupling constants for TrpH*+ calculated using density functional theory methods but only if water molecules are explicitly included in the calculation. PMID:17764168

Kiryutin, Alexey S; Morozova, Olga B; Kuhn, Lars T; Yurkovskaya, Alexandra V; Hore, P J

2007-09-27

359

(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

360

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

361

Regulation by membrane sialic acid of beta1H-dependent decay-dissociation of amplification C3 convertase of the alternative complement pathway.  

PubMed

Sheep erythrocytes in their native state did not activate the alternative complement pathway, as measured by lysis in dilutions of normal human serum containing [ethylenebis(oxyethylenenitrilo)] tetraacetic acid but acquired this capacity after membrane sialic acid residues had been removed (by sialidase) or modified (by NaIO(4)). Activation of the alternative pathway by sheep erythrocytes required removal or modification of at least 40% of the membrane sialic acid to reach threshold, and it increased proportionately when larger amounts of sialic acid had been affected. Studies with isolated proteins of the alternative pathway demonstrated that the altered erythrocyte membranes resembled natural activators in protecting bound C3b from inactivation by C3b inactivator and beta1H and protecting bound amplification C3 convertase (C3b,Bb) from decay-dissociation by beta1H. A 1% decrease in intact sialic acid was associated with a 1% decrease in beta1H activity in decay-dissociation of membrane bound C3b,Bb. Because removal of the C8 and C9 carbon atoms from the polyhydroxylated side chain of sialic acid by oxidation with NaIO(4) was functionally equivalent to removal of the entire sialic acid moiety, secondary effects of the latter reaction, such as diminution of the negative charge of the membrane or exposure of penultimate galactose residues, were not considered to be responsible for the altered activity of beta1H. These studies suggest that facilitation, by membrane sialic acid residues, of the interaction between bound C3b and beta1H is essential to prevent the particle from effectively activating the alternative pathway. PMID:273923

Fearon, D T

1978-04-01

362

Magnesium Silicate Dissolution Investigated by 29Si MAS, 1H-29Si CP MAS, 25Mg QCPMG, and 1H-25Mg CP QCPMG NMR  

SciTech Connect

Olivine has been the subject of frequent investigation in the earth sciences because of its simple structure and rapid dissolution kinetics. Several studies have observed a preferential release of magnesium with respect to silica during weathering under acidic conditions, which has been correlated to the formation of a silicon rich leached layer. While leached layer formation has been inferred through the changing solution chemistry, a thorough spectroscopic investigation of olivine reacted under acidic conditions has not been conducted. In particular, the fate of magnesium in the system is not understood and spectroscopic interrogations through nuclear magnetic resonance can elucidate the changing magnesium coordination and bonding environment. In this study, we combine analysis of the changing solution chemistry with advanced spectroscopic techniques (29Si MAS, 1H-29Si CP MAS, 25Mg QCPMG, and 1H-25Mg 2 CP QCPMG NMR) to probe leached layer formation and possible secondary phase precipitation during the dissolution of forsterite at 150 oC.

Davis, Michael C.; Brouwer, William J.; Wesolowski, David J.; Anovitz, Lawrence M.; Lipton, Andrew S.; Mueller, Karl T.

2009-08-01

363

Elevated Glutamatergic Compounds in Pregenual Anterior Cingulate in Pediatric Autism Spectrum Disorder Demonstrated by 1H MRS and 1H MRSI  

Microsoft Academic Search

Recent research in autism spectrum disorder (ASD) has aroused interest in anterior cingulate cortex and in the neurometabolite glutamate. We report two studies of pregenual anterior cingulate cortex (pACC) in pediatric ASD. First, we acquired in vivo single-voxel proton magnetic resonance spectroscopy (1H MRS) in 8 children with ASD and 10 typically developing controls who were well matched for age,

Anthony Bejjani; Joseph ONeill; John A. Kim; Andrew J. Frew; Victor W. Yee; Ronald Ly; Christina Kitchen; Noriko Salamon; James T. McCracken; Arthur W. Toga; Jeffry R. Alger; Jennifer G. Levitt

2012-01-01

364

Spectroscopic studies on methyl torsional behavior in 1-methyl-2(1H)-pyridone, 1-methyl-2(1H)-pyridinimine, and 3-methyl-2(1H)-pyridone. I. Excited state.  

PubMed

The laser induced fluorescence excitation and dispersed fluorescence spectra of three nitrogen heterocyclic molecules 1-methyl-2(1H)pyridone (1MPY), 1-methyl-2(1H)pyridinimine (1MPI), and 3-methyl-2(1H)pyridone (3MPY) have been studied under supersonic jet cooled condition. The methyl torsional and some low frequency vibrational transitions in the fluorescence excitation spectrum were assigned for 1MPY. These new assignments modify the potential parameters to the methyl torsion reported earlier. Some striking similarities exist between the torsional and vibrational transitions in the fluorescence excitation spectra of 1MPY and 1MPI. Apart from pure torsional transitions, a progression of vibration-torsion combination bands was observed for both these molecules. The excitation spectrum of 3MPY resembles the spectrum of its parent molecule, 2-pyridone. The barrier height of the methyl torsion in the excited state of 3MPY is highest amongst all these molecules, whereas the barrier in 1MPI is higher than that of 1MPY. To get an insight into the methyl torsional barrier for these molecules, results of the ab initio calculations were compared with the experimental results. It was found that the conformation of the methyl group undergoes a 60 degrees rotation in the excited state in all these molecules with respect to their ground state conformation. This phase shift of the excited state potential is attributed to the pi*-sigma* hyperconjugation between the out-of-plane hydrogen of the methyl group and the molecular frame. It has been inferred that the change in lowest unoccupied molecular orbital energy plays the dominant role in the excited state barrier formation. PMID:17381211

Sinha, Rajeev K; Pradhan, B; Wategaonkar, S; Singh, Bhanu P; Kundu, T

2007-03-21

365

Spectroscopic studies on methyl torsional behavior in 1-methyl-2(1H)-pyridone, 1-methyl-2(1H)-pyridinimine, and 3-methyl-2(1H)-pyridone. I. Excited state  

NASA Astrophysics Data System (ADS)

The laser induced fluorescence excitation and dispersed fluorescence spectra of three nitrogen heterocyclic molecules 1-methyl-2(1H)pyridone (1MPY), 1-methyl-2(1H)pyridinimine (1MPI), and 3-methyl-2(1H)pyridone (3MPY) have been studied under supersonic jet cooled condition. The methyl torsional and some low frequency vibrational transitions in the fluorescence excitation spectrum were assigned for 1MPY. These new assignments modify the potential parameters to the methyl torsion reported earlier. Some striking similarities exist between the torsional and vibrational transitions in the fluorescence excitation spectra of 1MPY and 1MPI. Apart from pure torsional transitions, a progression of vibration-torsion combination bands was observed for both these molecules. The excitation spectrum of 3MPY resembles the spectrum of its parent molecule, 2-pyridone. The barrier height of the methyl torsion in the excited state of 3MPY is highest amongst all these molecules, whereas the barrier in 1MPI is higher than that of 1MPY. To get an insight into the methyl torsional barrier for these molecules, results of the ab initio calculations were compared with the experimental results. It was found that the conformation of the methyl group undergoes a 60° rotation in the excited state in all these molecules with respect to their ground state conformation. This phase shift of the excited state potential is attributed to the ?*-?* hyperconjugation between the out-of-plane hydrogen of the methyl group and the molecular frame. It has been inferred that the change in lowest unoccupied molecular orbital energy plays the dominant role in the excited state barrier formation.

Sinha, Rajeev K.; Pradhan, B.; Wategaonkar, S.; Singh, Bhanu P.; Kundu, T.

2007-03-01

366

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

367

Hyperspectral analysis of IR data from a background scene  

Microsoft Academic Search

The Swedish Defence Research Agency (FOI) has performed systematic measurements on a background scene over a period of one year, and established an IR-background database. It has, and will, be used for a wide range of applications and provide a basis for the modeling of IR-background properties of Swedish terrain. The database consists of traditional IR images and hyperspectral IR

Paer Nilsson; Claes Nelsson

2003-01-01

368

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

NASA Technical Reports Server (NTRS)

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

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

1998-01-01

369

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

370

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

NASA Astrophysics Data System (ADS)

The explosive hexahydro-1,3,5-trinitro-s-triazine (CH 2-N-NO 2) 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 MHz. The results have been interpreted as due to hindered rotation of the NO 2 group about the N-NO 2 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 14NO 2 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 NO 2 group about the N-NO 2 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 NO 2 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.

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

2011-12-01

371

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

372

Alzheimer Disease: Postmortem Neuropathologic Correlates of Antemortem 1H MR Spectroscopy Metabolite Measurements  

PubMed Central

Purpose To determine the neuropathologic correlates of antemortem hydrogen 1 (1H) magnetic resonance (MR) spectroscopy metabolite measurements in subjects with Alzheimer disease (AD)-type pathology. Materials and Methods This study was approved by the institutional review board and was compliant with HIPAA regulations. Informed consent was obtained from each subject. The authors identified 54 subjects who underwent antemortem 1H MR spectroscopy and were clinically healthy or had AD-type pathology with low to high likelihood of AD according to National Institute on Aging–Reagan neuropathologic criteria at autopsy. They investigated the associations between 1H MR spectroscopy metabolite measurements and Braak neurofibrillary tangle stage (Braak stage), neuritic plaque score, and AD likelihood, with adjustments for subject age, subject sex, and time between 1H MR spectroscopy and death. Results Decreases in N-acetylaspartate–to-creatine ratio, an index of neuronal integrity, and increases in myo-inositol–to-creatine ratio were associated with higher Braak stage, higher neuritic plaque score, and greater likelihood of AD. The N-acetylaspartate–to–myo-inositol ratio proved to be the strongest predictor of the pathologic likelihood of AD. The strongest association observed was that between N-acetylaspartate–to–myo-inositol ratio and Braak stage (RN2 = 0.47, P < .001). Conclusion Antemortem 1H MR spectroscopy metabolite changes correlated with AD-type pathology seen at autopsy. The study findings validated 1H MR spectroscopy metabolite measurements against the neuropathologic criteria for AD, and when combined with prior longitudinal 1H MR spectroscopy findings, indicate that these measurements could be used as biomarkers for disease progression in clinical trials. PMID:18566174

Kantarci, Kejal; Knopman, David S.; Dickson, Dennis W.; Parisi, Joseph E.; Whitwell, Jennifer L.; Weigand, Stephen D.; Josephs, Keith A.; Boeve, Bradley F.; Petersen, Ronald C.; Jack, Clifford R.

2009-01-01

373

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

E-print Network

It is well known that generic two-Higgs-doublet models (2HDMs) suffer from potentially large Higgs-mediated flavor-changing neutral current (FCNC) problem, unless additional symmetries are imposed on the Higgs fields thereby respecting the Natural Flavor Conservation Criterion (NFC) by Glashow and Weinberg. A common way to respect the NFC is to impose Z_2 symmetry which is softly broken by a dim-2 operator. Another new way is to introduce local U(1)_H Higgs flavor symmetry that distinguishes one Higgs doublet from the other. In this paper, we consider the Higgs phenomenology in Type-I 2HDMs with the U(1)_H symmetry with the simplest U(1)_H assignments that the SM fermions are all neutral under U(1)_H, and we make detailed comparison with the ordinary Type-I 2HDM. After imposing various constraints such as vacuum stability and perturbativity as well as the electroweak precision observables and collider search bounds on charged Higgs boson, we find that the allowed Higgs signal strengths in our model are much broader than those in the ordinary Type-I 2HDM, because of newly introduced U(1)_H-charged singlet scalar and U(1)_H gauge boson. Still the ATLAS data on gg to h to gamma gamma cannot be accommodated. Our model could be distinguished from the ordinary 2HDM with the Z_2 symmetry in a certain parameter region and some channels. If the couplings of the new boson turn out to be close to those in the SM, it would be essential to search for extra U(1)_H gauge boson and/or one more neutral scalar boson to distinguish two models.

P. Ko; Yuji Omura; Chaehyun Yu

2013-12-28

374

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

375

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 ...

376

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

PubMed

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

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

2014-07-21

377

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

378

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

379

Chlorine Transfer Reactions between Chloramine and 1-Piperidine: Kinetic Reactivity and Characterization in a  

E-print Network

1 Chlorine Transfer Reactions between Chloramine and 1- Piperidine: Kinetic Reactivity) 98-111" #12;2 Abstract The kinetics of the chlorine transfer reaction between chloramine and 1H ranging between 8.25 and 12.89. The chlorine transfer reaction resulted in the formation of 1

Boyer, Edmond

380

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

381

Vibrational spectra and electronic structure of 3-((1H-pyrrol-1-yl) methyl) naphthalen-2-ol - A computational insight on antioxidant active Mannich base  

NASA Astrophysics Data System (ADS)

The 3-((1H-pyrrol-1-yl) methyl) naphthalen-2-ol (IFTN) is a class of synthesized organic Mannich base compound having antioxidant property of biological importance. A meticulous normal mode vibrational analysis has been carried out by comparing and contrasting the experimentally recorded FT-IR and FT-Raman spectra with simulated spectra of IFTN. Similarly the calculated 1H and 13C NMR of IFTN were correlated with experimental findings to understand the shielding and deshielding nature hold in it. The following other electronic structure properties were calculated such as equilibrium geometrical parameters, natural bond orbital analysis (NBO), frontier molecular orbital (FMO) characterization, statistical thermochemical properties against a range of temperatures and molecular electrostatic potential (MEP) imprint was carried out along with various charges such as APT, ESP, Hirshfeld, natural and Mulliken. All these predicted properties unlock the nature of total behavior of IFTN in various dimensions. These could be Lewis, non-Lewis interaction along with their respective energies, contribution of fragmented moieties for various orders of HOMO and LUMO, temperature consequences on enthalpy, entropy, and heat capacity. In addition, the MEP leads to find electrophilic, nucleophilic reactive sites on IFTN molecular surface. The entire computational calculations has been made on HF/6-31+G/6-311++G(d,p) and B3LYP/6-31+G/6-311++G(d,p) model chemistries. A complete electronic structure observation has been achieved by this theoretical analysis.

Boobalan, Maria susai; Tamilvendan, D.; Amaladasan, M.; Ramalingam, S.; Venkatesa Prabhu, G.; Bououdina, M.

2015-02-01

382

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

383

Synthesis, spectroscopic and structural characterization of 5-benzoyl-4-phenyl-2-methylthio-1H-pyrimidine with theoretical calculations using density functional theory  

NASA Astrophysics Data System (ADS)

In this paper, we will report a combined experimental and theoretical investigation of the molecular structure and spectroscopic parameters (FT-IR, 1H NMR, 13C NMR) of 5-benzoyl-4-phenyl-2-methylthio-1H-pyrimidine. The compound crystallizes in the triclinic space group P-1 with Z = 2. The molecular geometry was also optimized using density functional theory (DFT/B3LYP) method with the 6-311G(d,p) and 6-311++G(d,p) basis sets in ground state and compared with the experimental data. All the assignments of the theoretical frequencies were performed by potential energy distributions using VEDA 4 program. Information about the size, shape, charge density distribution and site of chemical reactivity of the molecules has been obtained by mapping electron density isosurface with electrostatic potential (ESP). Also, non-linear optical properties of the title compound were performed at B3LYP/6-311++G(d,p) level. The theoretical results showed an excellent agreement with the experimental values.

?nkaya, Ersin; Dinçer, Muharrem; ?ahan, Emine; Y?ld?r?m, ?smail

2013-10-01

384

Synthesis and characterization of 3-methyl-5-oxo-N,1-diphenyl-4,5-dihydro-1-H-pyrazole-4-carbothioamide and its metal complexes.  

PubMed

The molecular parameters have been calculated to confirm the geometry of 3-methyl-5-oxo-N,1-diphenyl-4,5-dihydro-1-H-pyrazole-4-carbothioamide, HL. The compound is introduced as a new chelating agent for complexation with Cr(III), Fe(III), Co(II), Ni(II) and Cu(II) ions. The isolated chelates were characterized by partial elemental analyses, magnetic moments, spectra (IR, UV-vis, ESR; (1)H NMR) and thermal studies. The protonation constant of HL (5.04) and the stepwise stability constants of its Co(II), Cu(II), Cr(III) and Fe(III) complexes were calculated. The ligand coordinates as a monobasic bidentate through hydroxo and thiol groups in all complexes except Cr(III) which acts as a monobasic monodentate through the enolized carbonyl oxygen. Cr(III) and Fe(III) complexes measured normal magnetic moments; Cu(II) and Co(II) measured subnormal while Ni(II) complex is diamagnetic. The data confirm a high spin and low spin octahedral structures for the Fe(III) and Co(II) complexes. The ESR spectrum of the Cu(II) complex support the binuclear structure. The molecular parameters have also been calculated for the Cu(II) and Fe(III) complexes. The thermal decomposition stages of the complexes confirm the MS to be the residual part. Also, the thermodynamic and kinetic parameters were calculated for some decomposition steps. PMID:19647478

El-Shazly, R M

2009-09-15

385

Efficient radiometrically accurate synthetic representation of IR scenes  

Microsoft Academic Search

A technique is developed for synthesizing a high spectral resolution IR ship signature image, for use in an imaging IR Anti-Ship Cruise Missile (ASCM) model, from an IR scene database provided by the ship signature model NTCS\\/ShipIR. This synthesized IR ship image is generated for use over ranges representative of an ASCM engagement. The technique presented focuses on the application

Patrick C. Shaw; Robert E. Gover

2003-01-01

386

Realistic approach to an IR mission rehearsal simulator  

Microsoft Academic Search

This paper describes the development of a computer based infrared mission rehearsal system (IR-MRS). The IR-MRS can be used for IR mission planning, selecting navigation waypoints, and for mission rehearsal. For specific scenarios, locales, and environments the IR-MRS can simulate ingress\\/egress corridors and realistic target engagement ranges. In addition, the sensor model's modular design allows the IR-MRS to have a

Matthew Donn; Philip Yanni; Uri Bernstein

1996-01-01

387

IR signature management for the modern navy  

NASA Astrophysics Data System (ADS)

A methodology for analysing the infrared (IR) signature and susceptibility of naval platforms using ShipIR/NTCS was presented by Vaitekunas (2010). This paper provides three key improvements: use of a larger climatic data set (N=100), a new target sub-image algorithm eliminating false detections from pixel-aliasing at the horizon, and a new seeker model interfacing with a line-by-line background clutter model. Existing commercial stealth technologies (exhaust stack suppression, low solar absorptive paints, extended hull film-cooling) are re-analysed using the new models and methods to produce a more rigorous and comprehensive analysis of their effectiveness based on the statistics of reduction in IR susceptibility. These methods and results combined with the cost of each stealth option should allow platform managers to select an appropriate level of infrared suppression and establish the design criteria for a new ship.

Vaitekunas, David A.; Kim, Yoonsik

2013-06-01

388

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

389

Structural analysis of photodegraded lime wood by means of FT-IR and 2D IR correlation spectroscopy.  

PubMed

In this study the weathering behavior of lime wood (Tillia cordata Mill.) has been examined using FT-IR and 2D IR correlation spectroscopy, which evidenced chemical changes induced by exposure to weathering conditions. It was showed that lignin is most sensitive component to the photodegradation processes as indicated by considerable decreases in the intensities of the characteristic aromatic lignin band at 1505cm(-1) and other associated bands. By 2D correlation spectroscopy has been demonstrated that the moment of CO from carboxyl and acetyl groups in hemicelluloses is changing first, followed by the CC of aromatic skeletal, CO in non-conjugated ketones, carboxyl groups and lactones, absorbed O-H and conjugated C-O groups in quinones. The carbonyl formation corresponded well with lignin degradation, indicating a close relationship between them. Comparing the rate of carbonyl formation and lignin decay clearly showed that the former is remarkably higher than the latter, indicating the formation of carbonyl bands at 1738cm(-1) probably resulted from not only lignin oxidation but also from reactions occurring in other components of the wood. Quinine formation is combined with the decay of aromatic structures and the formation of conjugated carbonyl groups. PMID:21349282

Popescu, Carmen-Mihaela; Popescu, Maria-Cristina; Vasile, Cornelia

2011-05-01

390

Hematocrit and Oxygenation Dependence of Blood 1H2O T1 At 7 Tesla  

PubMed Central

Knowledge of blood 1H2O T1 is critical for perfusion-based quantification experiments such as arterial spin labeling (ASL) and CBV-weighted MRI using vascular space occupancy (VASO). The dependence of blood 1H2O T1 on hematocrit fraction (Hct) and oxygen saturation fraction (Y) was determined at 7 Tesla using in vitro bovine blood in a circulating system under physiological conditions. Blood 1H2O R1 values for different conditions could be readily fitted using a two-compartment (erythrocyte and plasma) model which are described by a monoexponential longitudinal relaxation rate constant dependence. It was found that T1 = 2171±39 ms for Y = 1 (arterial blood) and 2010±41 ms for Y = 0.6 (venous blood), for a typical Hct of 0.42. The blood 1H2O T1 values in the normal physiological range (Hct from 0.35 to 0.45, and Y from 0.6 to 1.0) were determined to range from 1900 ms to 2300 ms. The influence of oxygen partial pressure (pO2) and the effect of plasma osmolality for different anticoagulants were also investigated. It is discussed why blood 1H2O T1 values measured in vivo for human blood may be about 10-20% larger than found in vitro for bovine blood at the same field strength. PMID:23169066

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

2012-01-01

391

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

392

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

393

WFC3 SS IR Internal Flats  

NASA Astrophysics Data System (ADS)

Part of side switch activities.Flat field ramps will be acquired through each of the IR channel's 15 filters. Sample sequences and exposure times are dictated by the Tungsten lamp flux levels observed in Thermal Vacuum testing. The order in which the filters are used within each Visit and from Visit to Visit was optimized to allow the observations to fit within 30 minute orbits, and also in order to investigate and track any persistence effects resulting from the varying illumination levels on the IR detector.ID: WF20

MacKenty, John

2012-10-01

394

Efficient synthesis of 2,3-disubstituted-2,3-dihydroquinazolin-4(1H)-ones catalyzed by dodecylbenzenesulfonic acid in aqueous media under ultrasound irradiation.  

PubMed

Synthesis of 2,3-disubstituted-2,3-dihydroquinazolin-4(1H)-one derivatives catalyzed by dodecylbenzenesulfonic acid was carried out in 80-92% yields at 40-42°C within 1-2h in aqueous media via one-pot three-component condensation of isatoic anhydride, aromatic aldehyde and amine under ultrasound irradiation. Convenient work-up procedures, mild reaction conditions, avoiding the use of organic solvents, and friendly to environment are the salient features of this protocol. PMID:25224856

Chen, Bao-Hua; Li, Ji-Tai; Chen, Guo-Feng

2015-03-01

395

1,3-Bis(4-meth­oxy­benz­yl)-6-methyl­pyrimidine-2,4(1H,3H)-dione  

PubMed Central

The title compound, C21H22N2O4, was prepared by reaction of 6-methyl­pyrimidine-2,4(1H,3H)-dione and 1-chloro­methyl-4-meth­oxy­benzene. In the title mol­ecule, the central pyrimidine ring forms dihedral angles of 62.16?(4) and 69.77?(3)° with the two benzene rings. In the crystal, weak inter­molecular C—H?O hydrogen bonds link the mol­ecules into chains. PMID:21588055

Li, Gong-Chun; Zhang, Li-Ke; Ju, Zhi-Yu; Yang, Feng-Ling

2010-01-01

396

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

397

Effect of fertilizers on galanthamine and metabolite profiles in Narcissus bulbs by 1H NMR.  

PubMed

Narcissus bulbs contain the biologically active alkaloid galanthamine, and Narcissus is being developed as a natural source of the molecule for the pharmaceutical industry. The effect of fertilizer on galanthamine production was investigated in a field study using a (1)H nuclear magnetic resonance (NMR) metabolite profiling approach. Galanthamine was quantitated and major metabolites in the bulbs were identified. The application of standard fertilization levels of nitrogen and potassium caused a significant increase in galanthamine as compared to a control. Multivariate data analysis of the (1)H NMR data revealed that applying double the standard level of nitrogen fertilizer resulted in production of more amino acids and citric acid cycle intermediates, but not more galanthamine. The results indicated that standard levels of fertilizer currently applied in The Netherlands are sufficient for optimal galanthamine accumulation in the bulbs. This study shows how (1)H NMR-based metabolic profiling can provide insight into the response of plant metabolism to agricultural practices. PMID:21375239

Lubbe, Andrea; Choi, Young Hae; Vreeburg, Peter; Verpoorte, Robert

2011-04-13

398

Multislice 1H magnetic resonance spectroscopic imaging: assessment of epilepsy, Alzheimer's disease, and amyotrophic lateral sclerosis  

NASA Astrophysics Data System (ADS)

Proton magnetic resonance spectroscopic imaging (1H MRSI) with volume pre-selection (i.e. by PRESS) or multislice 1H MRSI was used to investigate changes in brain metabolites in Alzheimer's disease, epilepsy, and amyotrophic lateral sclerosis. Examples of results from several ongoing clinical studies are provided. Multislice 1H MRSI of the human brain, without volume pre-selection offers considerable advantages over previously available techniques. Furthermore, MRI tissue segmentation and completely automated spectra curve fitting greatly facilitate quantitative data analysis. Future efforts will be devoted to obtaining full brain coverage and data acquisition at short spin echo times (TE less than 30 ms) for the detection of metabolites with short T2 relaxation times.

Weiner, Michael W.; Maudsley, Andrew A.; Schuff, Norbert; Soher, Brian J.; Vermathen, Peter P.; Fein, George; Laxer, Kenneth D.

1998-07-01

399

Cross Sections of Proton Induced Nuclear Reactions on Iridium  

SciTech Connect

Excitation functions of the reactions natIr(p,xn)188,189,191Pt and natIr(p,x)186,187,188,189,190,192Ir were measured up to 70 MeV for practical applications. The measured experimental data were compared with the earlier results and analyzed using theoretical calculations based on the model code Alice-IPPE, The new experimental data show significant deviations from the earlier experimental results. Good agreement was found on average with the model calculation. Applications are also discussed.

Tarkanyi, F.; Ditroi, F.; Takacs, S.; Kiraly, B. [Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), 4026 Debrecen (Hungary); Hermanne, A. [Cyclotron Laboratory, Vrije Universiteit Brussel, 1090 Brussels (Belgium); Uddin, M.S.; Hagiwara, M.; Baba, M. [Cyclotron and Radioisotope Center, Tohoku University, Sendai 980-8578 (Japan); Shubin, Yu.N.; Dityuk, A.I. [Institute of Physics and Power Engineering, Obninsk 249020 (Russian Federation)

2005-05-24

400

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

PubMed

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

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

2007-12-01

401

Synthesis, spectroscopic and structural evaluation of ethyl 2-cyano-3-{5-[(4-nitro-benzoyl)-hydrazonomethyl]-1H-pyrrol-2-yl}-acrylate using experimental and theoretical approaches  

NASA Astrophysics Data System (ADS)

A new C-vinylpyrrole containing aroylhydrazone, ethyl 2-cyano-3-{5-[(4-nitro-benzoyl)-hydrazonomethyl]-1H-pyrrol-2-yl}-acrylate (ECNBHPA) derived from ethyl 2-cyano-3-(5-formyl-1H-pyrrol-2-yl)-acrylate and 4-nitro-benzohydrazide has been characterized by various spectroscopic techniques (1H NMR, 13C NMR, Mass, UV-Visible, Emission, FT-IR). TD-DFT has been used to calculate the various electronic excitations and their nature within molecule. The emission spectra of ECNBHPA show photoluminescent behavior of title molecule. Natural bond orbital (NBO) analysis has been carried out to explore the various conjugative/hyperconjugative interactions within molecule and their second order stabilization energy (E(2)). A combined experimental and theoretical vibrational analysis designates presence of the classical hydrogen bonding N1sbnd H29⋯N9 between pyrrole Nsbnd H as proton donor and N atom of cyanide as proton acceptor. To determine the strength and nature of hydrogen bonding, topological parameters at bond critical points (BCP) have been analyzed by 'Quantum theory of atoms in molecules' (QTAIM) in detail. The result of hydrogen bonding is obvious in 1H NMR, FT-IR and ESP map as down field chemical shift, vibrational red shift and absence of blue colur relative to pyrrole Nsbnd H proton, respectively. Global electrophilicity index (? = 6.573 eV) shows that title molecule behaves as a strong electrophile. The local reactivity descriptors analyses such as Fukui functions (fk+,fk-), local softnesses (sk+,sk-) and electrophilicity indices (?k+,?k-) have been performed to determine the reactive sites within molecule. The first hyperpolarizability (?0) of ECNBHPA has been computed to evaluate the non-linear optical (NLO) response of the investigated molecule.

Singh, R. N.; Kumar, Amit; Rawat, Poonam; Srivastsva, Anchal

2013-10-01

402

Taxol reactions.  

PubMed

Paclitaxel (Taxol) a taxane antineoplastic agent causing irreversible microtubule aggregation with activity against breast, ovarian, lung, head and neck, bladder, testicular, esophageal, endometrial and other less common tumors was derived from the bark of the Pacific yew (Taxus brevifolia). Phase I trials conducted in the late 1980s were almost halted because of the high frequency of hypersensitivity-like reactions. Respiratory distress (dyspnea and/or bronchospasm), hypotension, and angioedema were the major manifestations, but flushing, urticaria, chest, abdomen, and extremity pains were described also. Reactions occurred on first exposure in the majority of cases raising etiologic questions. The vehicle for paclitaxel Cremophor EL (polyoxyethylated castor oil in 50% ethanol) was strongly suspect as a direct (non-immunoglobulin E dependent) histamine releaser. Premedication regimens and longer infusion times lowered the incidence of reactivity allowing phase II and III trials to progress through the early 1990s. The mechanism(s) underlying paclitaxel hypersensitivity-like reactions is still unknown, and clinical data on probable complement and mast cell activation are lacking. The original clinical trial protocols for paclitaxel required discontinuation of therapy for patients who experienced hypersensitivity-like reactions. Here, we review the current etiologic knowledge of these reactions and describe our clinical approach to allow completion of chemotherapy with this powerful plant-derived agent. PMID:12125509

Price, Kursteen S; Castells, Mariana C

2002-01-01

403

Feeding of the 1 1/2- isomers in stable Ir and Au isotopes  

SciTech Connect

Excited states were studied and absolute partial {gamma}-ray cross sections were measured using the ({eta}, {eta}'{gamma}) reaction in {sup 191}Ir, {sup 193}Ir and {sup 197}Au. A Compton-suppressed germanium-detector array (GEANIE) for {gamma}-ray spectroscopy and the broad-spectrum pulsed neutron source of the Los Alamos Neutron Science Center's WNR facility were used for the measurement. The energy of the incident neutrons was determined using the time-of-flight technique. Absolute partial {gamma}-ray cross sections were measured up to incident neutron energy of 20 MeV for several transitions feeding directly the 1 1/2- isomers and ground states in {sup 191}Ir, {sup 193}Ir and {sup 197}Au. The feeding of the 1 1/2- isomers, which originate from the odd proton occupying the h{sub 1 1/2} orbital, was found for the three targets to be very similar and increasing relative to the feeding of the corresponding ground state with increasing neutron energy up to E{sub n} {approx} 10 MeV. Above this neutron energy the opening of the (n, 2{sub n}) reaction channel strongly affects the population of the isomers and leads to a decrease of their relative population compared to the population of the ground states. The experimental results are compared with theoretical predictions from the GNASH reaction model calculation implementing a version of the spin distribution for the pre-equilibrium reaction piece with either a compound nucleus spin distribution (CN-GNASH) or a Feshbach-Kerman-Koonin (FKK-GNASH) quantum mechanical spin distribution. The effects of the spin cutoff parameter values on the population of states are examined. Evidence is presented that FKK-GNASH provides a description of the experimental data that mitigates the need for adjustment of the level density parameter to fit the data.

Fotiadis, Nikolaos [Los Alamos National Laboratory; Nelson, Ronald O [Los Alamos National Laboratory; Devlin, Matthew [Los Alamos National Laboratory; Holloway, Shannon T [Los Alamos National Laboratory; Kawano, Toshihiko [Los Alamos National Laboratory; Talou, Patrick [Los Alamos National Laboratory; Chadwick, Mark B [Los Alamos National Laboratory; Becker, John A [LLNL; Garrett, Paul E [U GUELPH, CANADA

2008-01-01

404

A flexible Au-Ir cell with quick assembly for hydrothermal experiments  

USGS Publications Warehouse

The paper describes a new flexible reaction cell for high-temperature and high-pressure experiments in hydrothermal apparatus. The interior of the cell is all Au, except for two inert Ir gaskets. The design features an all Au cap that can be easily and rapidly assembled and disassembled. The capacity of the cell is approximately 240 mL, with a height of 20 cm and an o.d. of 6 cm. -Authors

Rosenbauer, R.J.; Bischoff, J.L.; Potter, J.M.

1993-01-01

405

Model for simulation of IR countermeasure effect on IR-seeker/missile  

NASA Astrophysics Data System (ADS)

TACSI (TACtical SImulation) is an existing simulator used as a tactical environment for manned simulators at Saab Aerosystems. TACSI can also be used as a stand-alone desktop development and simulation tool. TACSI simulates a large number of entities and functions such as platforms, sensors, weapons, signatures, communication, multisensor fusion, decision support etc. TACSI has a rule based pilot model and uses High Level Architecture (HLA) for interfacing with other simulation models. This model, a development of TACSI, simulates the flight dynamics, IR-signature and IR-seeker operation. The dynamic behaviour of the aircraft, the IRCM, the missile and the IR-seeker are modelled. The IR-contrast seen by the seeker through the atmosphere in front of the aircraft and the IRCM are spectrally and dynamically modelled. The seeker operation behaviour and function are also modelled. To implement this in a real-time simulation system simplifications are necessary. This paper describes the simplifications to model the IR-contrast and the seeker function. This model is used to analyse the effect of IR countermeasures (IRCM) on a missile IR-seeker.

Berggren, Jan; Kihlen, Ralf G.

2004-12-01

406

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

PubMed Central

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

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

2013-01-01

407

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

NASA Astrophysics Data System (ADS)

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

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

2005-04-01

408

Complete 1H and 13C data assignments of two new guaianolides isolated from Ainsliaea fragrans.  

PubMed

Two new guaianolides, 8alpha-hydroxy-11alpha,13-dihydroglucozaluzanin C and 11alpha,13-dihydroglucozaluzanin C, were isolated from Ainsliaea fragrans, along with two known guaianolides, 8alpha-hydroxy-11alpha,13-dihydrozaluzanin C and glucozaluzanin C. The structures of the new compounds were unambiguously established by HR-ESI-MS, one-dimensional (1D) (DEPT), two-dimensional (2D) ((1)H-(1)H COSY, HSQC, HMBC, ROESY) NMR experiments and by comparison with structurally related compounds. The known compounds were identified by comparison of spectral data with published references. Some NMR data of the known compounds were reported for the first time. PMID:18727163

Li, Xingshang; Liu, Jiangyun; Cai, Jinna; Cai, Peilie

2008-11-01

409

Platinum Monolayer Electrocatalysts for O2 Reduction: Pt Monolayer on Carbon-Supported PdIr Nanoparticles  

SciTech Connect

The kinetics of oxygen reduction was investigated in acid solutions on Pt monolayers deposited on modified carbon-supported PdIr nanoparticles using the rotating disk-electrode technique. Iridium is introduced into the Pd substrate in order to fine-tune the Pt-Pd interactions and to improve Pd stability under operating conditions of the fuel cell. The kinetics of the oxygen reduction reaction shows enhancement with the Pt monolayer on the PdIr nanoparticle surfaces in comparison with the reaction on Pt/C and Pt monolayer on Pd/C nanoparticles. The electrochemical measurements suggest that reduced oxidation of Pt monolayer on PdIr/C compared to Pt/C and Pt monolayer on Pd/C is the cause of enhanced activity. Besides a ligand effect induced to the Pt surface by the presence of PdIr in the second sublayer of the nanoparticle, as suggested by our density functional theory analysis, Ir also leads to a Pd skin contraction, so the Pt monolayer on PdIr/C is compressed more than on Pd/C. Both effects lead to further weakening of the Pt-OH interaction, thus increasing the ORR activity. The Pt-specific activity for Pt{sub ML}PdIr/C is three times and 25% higher than that of Pt/C and Pt{sub ML}Pd/C respectively; the Pt-mass activity of Pt{sub ML}PdIr/C is more than 20 times and 25% higher than that of Pt/C and Pt{sub ML}Pd/C, respectively.

Vukmirovic, M.B.; Knupp, S.L. Haldar, P.; Herron, J.A.: Mavrikakis, M.; Adzic, R.R.

2010-11-01

410

Magnetic trap of a reaction zone  

NASA Astrophysics Data System (ADS)

The reaction of ethylene glycol oxidation catalyzed by a colloidal suspension of iron oxide nanoparticles was monitored by IR thermography under an inhomogeneous magnetic field (with a spatial gradient ˜50T2/m). The interaction of a reaction zone with the gradient magnetic field, in a way that the reaction zone could be trapped and manipulated at a desired position with the aid of the magnetic field effect, has been discovered. We explain this phenomenon by the magnetic buoyancy force arising from the variation in the magnetic susceptibility between the reaction zone and rest solution during the catalyzed redox process. These observations suggest the potential use magnetic fields for controlling chemical processes by the long-time localization of the reaction zone from the environment and enables complex problem solving to be performed in physics, chemistry, biology, chemical engineering, nanotechnology, and medicine.

Digilov, Rafael M.; Sheintuch, M.

2005-02-01

411

IR laser-induced protein crystal transformation  

PubMed Central

A method and the design of instrumentation, and its preliminary practical realisation, including test experiments, with the object of inducing phase changes of biomolecular crystals by controlled dehydration through heating with infrared (IR) light are described. The aim is to generate and select crystalline phases through transformation in the solid state which have improved order (higher resolution in X-ray diffraction experiments) and reduced mosaic spread (more uniformly aligned mosaic blocks) for diffraction data collection and analysis. The crystal is heated by pulsed and/or constant IR laser irradiation. Loss of crystal water following heating and its reabsorption through equilibration with the environment is measured optically by a video system. Heating proved superior to traditional controlled dehydration by humidity change for the test cases CODH (carbon monoxide dehydrogenase) and CLK2 (a protein kinase). Heating with IR light is experimentally simple and offers an exploration of a much broader parameter space than the traditional method, as it allows the option of varying the rate of phase changes through modification of the IR pulse strength, width and repeat frequency. It impacts the crystal instantaneously, isotropically and homogeneously, and is therefore expected to cause less mechanical stress. PMID:24816092

Kiefersauer, Reiner; Grandl, Brigitte; Krapp, Stephan; Huber, Robert

2014-01-01

412

IR-4 Ornamental Horticulture Program Trial Report  

E-print Network

(Gypsophila paniculata `Festival Star') IR4 PR#: 26038 Report date: May 29, 2007 Authors: Heiner Lieth Summary: Gypsophila paniculata `Festival Star' plants growing in 1-gallon containers received two. Phytotoxicity and growth changes over 8 weeks for Gypsophila paniculata `Festival Star' treated with 0 (Control

Lieth, J. Heinrich

413

IR-4 Ornamental Horticulture Program Trial Report  

E-print Network

(s): 26040 1 Project Title: Evaluation of phytotoxicity of V-10142 75WG on Baby's Breath (Gypsophila paniculata `Festival Star') IR4 PR#: 26040 Report date: May 29, 2007 Authors: Heiner Lieth and Linda Dodge Department of Plant Sciences University of California, Davis Davis, CA 95616 Narrative Summary: Gypsophila

Lieth, J. Heinrich

414

IR-4 Ornamental Horticulture Program Trial Report  

E-print Network

(s): 26036 1 Project Title: Evaluation of phytotoxicity of Sulfentrazone 0.2G on Baby's Breath (Gypsophila paniculata `Festival Star') IR4 PR#: 26036 Report date: May 29, 2007 Authors: Heiner Lieth and Linda Dodge Department of Plant Sciences University of California, Davis Davis, CA 95616 Narrative Summary: Gypsophila

Lieth, J. Heinrich

415

Limitations To Optical/IR Interferometry  

NASA Technical Reports Server (NTRS)

The primary limitation to ground-based optical/IR interferometry is the turbulent atmosphere, which limits sensitivity by restricting the coherence volume, limits imaging accuracy by corrupting the fringe phase, and limits astrometric acuracy by corrupting the angel of arrival.

Colavita, M. M.

1993-01-01

416

IR-4 Ornamental Horticulture Program Trial Report  

E-print Network

Narrative Summary: Salvia nemorosa `May Night' plants growing in 1-gallon containers received two for the Salvia nemorosa `May Night' plants treated with Sedgehammer were significantly higher than the controls damage on Salvia nemorosa `May Night' and should not be used "over the top". #12;IR-4 Ornamental

Lieth, J. Heinrich

417

LONG ISLAND SOUND STUDY 2002 CCMP IR  

EPA Science Inventory

The Long Island Sound Study Implementation Review (IR) summarizes the progress and challenges ahead for the for the Long Island Sound Study (LISS) through examination of it activities in relation to the CCMP. The LISS CCMP identified six major areas requiring management action: 1...

418

MID-IR IMAGING OF NATURAL FIBERS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Fourier Transform Mid-IR microspectroscopy has been used to identify compounds in various tissues of bio-based fibers. Mapping techniques have provided the location of specific components within the cell walls and interstitial spaces of tissues and identified compounds removed during the retting of...

419

Politics & IR Elections and Electoral Politics  

E-print Network

Politics & IR Elections and Electoral Politics Political Behavior Latino and Latin American Studies Politics & Law Top Sellers New Releases Coming Soon This volume describes and analyzes the proliferation. In so doing, it conveys fresh perspectives on the quality of democracy in Latin America today and about

Pulfrey, David L.

420

Flexible and efficient IR using array databases  

Microsoft Academic Search

The Matrix Framework is a recent proposal by IR researchers to flexibly represent all important information retrieval models in a single multi-dimensional array framework. Computational support for exactly this framework is provided by the array database system SRAM (Sparse Relational Array Mapping) that works on top of a DBMS. Information retrieval models can be specified in its comprehension-based array query

Roberto Cornacchia; Sándor Héman; Marcin Zukowski; Arjen P. De Vries; Peter A. Boncz

2008-01-01

421

TIJAH: Embracing IR Methods in XML Databases  

Microsoft Academic Search

This paper discusses our participation in INEX (the Initiative for the Evaluation of XML Retrieval) using the TIJAH XML-IR system. TIJAH's system design follows a 'standard' layered database architecture, carefully separating the conceptual, logical and physical levels. At the conceptual level, we classify the INEX XPath-based query expressions into three dierent query patterns. For each pattern, we present its mapping

Johan A. List; Vojkan Mihajlovic; Georgina Ramírez; Arjen P. De Vries; Djoerd Hiemstra; Henk Ernst Blok

2005-01-01

422

INFRA-RED SPECTROSCOPY: IR HELPER  

NSDL National Science Digital Library

This site provides a step-by-step tutorial on the interpretation of Infra-Red spectra. The student picks IR spectra from a drop-down menu and then proceeds through a guided process to determine the identity of the compound that generated the selected spectrum.

423

Flexible and efficient IR using array databases  

Microsoft Academic Search

The Matrix Framework is a recent proposal by IR researchers to flexibly represent all important information retrieval models in a single multi-dimensional array framework. Computational support for exactly this framework is provided by the array database system SRAM (Sparse Relational Array Mapping) that works on top of a DBMS. Information retrieval models can be specified in its comprehension-based array query

R. Cornacchia; S. Héman; M. Zukowski; Vries de A. P; P. A. Boncz

2007-01-01

424

IR circuit board and IC failure detection  

Microsoft Academic Search

This paper describes research and development efforts in the use of infrared (IR) laser beams for detecting failures in integrated circuits resident on printed circuit boards. This work involves taking advantage of the transparency of the silicon substrate of ICs to radiation in the near infrared (NIR) spectrum to devise a non-invasive method for imaging the component circuitry of the

Ernest Keenan; R. Glenn Wright; Marek Zgol; Robert Mulligan; Victor Tagliavia; Larry V. Kirkland

2004-01-01

425

Automatic NMR-based identification of chemical reaction types in mixtures of co-occurring reactions.  

PubMed

The combination of chemoinformatics approaches with NMR techniques and the increasing availability of data allow the resolution of problems far beyond the original application of NMR in structure elucidation/verification. The diversity of applications can range from process monitoring, metabolic profiling, authentication of products, to quality control. An application related to the automatic analysis of complex mixtures concerns mixtures of chemical reactions. We encoded mixtures of chemical reactions with the difference between the (1)H NMR spectra of the products and the reactants. All the signals arising from all the reactants of the co-occurring reactions were taken together (a simulated spectrum of the mixture of reactants) and the same was done for products. The difference spectrum is taken as the representation of the mixture of chemical reactions. A data set of 181 chemical reactions was used, each reaction manually assigned to one of 6 types. From this dataset, we simulated mixtures where two reactions of different types would occur simultaneously. Automatic learning methods were trained to classify the reactions occurring in a mixture from the (1)H NMR-based descriptor of the mixture. Unsupervised learning methods (self-organizing maps) produced a reasonable clustering of the mixtures by reaction type, and allowed the correct classification of 80% and 63% of the mixtures in two independent test sets of different similarity to the training set. With random forests (RF), the percentage of correct classifications was increased to 99% and 80% for the same test sets. The RF probability associated to the predictions yielded a robust indication of their reliability. This study demonstrates the possibility of applying machine learning methods to automatically identify types of co-occurring chemical reactions from NMR data. Using no explicit structural information about the reactions participants, reaction elucidation is performed without structure elucidation of the molecules in the mixtures. PMID:24551112

Latino, Diogo A R S; Aires-de-Sousa, João

2014-01-01

426

On substituted pyrazole derivatives. II. (E)-1-(4-{[1-(4-Fluorophenyl)-3,5-dimethyl-1H-pyrazol-4-yl]diazenyl}phenyl)ethanone and (E)-1-(4-chlorophenyl)-3,5-dimethyl-4-[2-(2-nitrophenyl)diazenyl]-1H-pyrazole.  

PubMed

The molecular structures of (E)-1-(4-{[1-(4-fluorophenyl)-3,5-dimethyl-1H-pyrazol-4-yl]diazenyl}phenyl)ethanone, C19H17FN4O, (III), and (E)-1-(4-chlorophenyl)-3,5-dimethyl-4-[2-(2-nitrophenyl)diazenyl]-1H-pyrazole, C17H14ClN5O2, (IV), prepared by reaction of the corresponding ?-diketohydrazones with substituted arylhydrazines in acid media, are nonplanar, with the planes of the lateral phenyl rings forming dihedral angles with that of the central pyrazole ring varying from 2.71?(7) to 45.22?(7)°. The crystal structures are supported by C-H...O, C-H...? and ?-? weak intermolecular interactions together with some unusual trifurcated C-Cl...Cl-C contacts, which are discussed in detail. PMID:25567576

Bustos, Carlos; Alvarez-Thon, Luis; Oportus, Tania; Mesías-Salazar, Angela; Baggio, Ricardo

2015-01-01

427

Interaction of thiazolidine-2-thione with 2,3,5,6-tetrabromo-1,4-benzoquinone: A set of sequential interactions involving redox and substitution reactions after an initial charge transfer complexation  

NASA Astrophysics Data System (ADS)

Interaction between thiazolidine-2-thione (T2T) as an electron donor and 2,3,5,6-tetrabromo-1,4-benzoquinone (p-bromanil, BRL) as a ?-electron acceptor has been studied by using several spectral techniques, viz. UV/visible, IR, 1H NMR and Mass spectra. A substitution reaction has been occurred after an initial formation of a CT complex, meanwhile a redox reaction has been occurred, in situ, too in which the interacting donor (T2T) has been oxidized to the corresponding thiazole. Thus, the stoichiometric ratio of this interaction has been found to be 2:1, T2T:BRL. However, the most interesting finding is that unexpectedly neither the SH group of the thiol form nor the NH group of the thione form of the T2T has shared in the substitution reaction with BRL. This finding has been confirmed by the different applied spectral tools, whereas a plausible reaction pathway has been illustrated and discussed.

Rabie, Usama M.; Abou-El-Wafa, Moustafa H. M.; Nassar, Heba

2012-02-01

428

Application of SVM Classifier in IR Target Recognition  

NASA Astrophysics Data System (ADS)

In the paper, support vector machine is proposed in IR target recognition. Grid method is used to select the appropriate parameters of SVM to avoid over-fitting due to the choice of inappropriate parameters. We employ coal mine IR monitoring images to testify the IR target recognition ability of SVM. And features and category of the coal mine IR monitoring images are given. The experimental results illustrate that the IR target recognition accuracy of SVM is 100%.Thus, SVM is an excellent IR target recognition method.

Wen-ge, Feng

429

Reaction Time  

NSDL National Science Digital Library

In this activity, learners conduct an experiment to test how fast they can react. Learners try to catch a piece of paper with a ruler printed on it (or a ruler) as quickly as they can. Learners collect data and compare the reaction times of friends and family.

Boston, Wgbh

2003-01-01

430

Reaction Time  

NSDL National Science Digital Library

This lab is not an inquiry activity. There are some students whose reaction times will not allow them to catch a 12 inch ruler. They may use a dowel, stick, strip of cardboard, etc. Although the students are led to believe that the point of the lab is to

Horton, Michael

2009-05-30

431

Synthesis of stereospecifically deuterated desoxypodophyllotoxins and 1H-nmr assignment of desoxypodophyllotoxin  

NASA Technical Reports Server (NTRS)

[4 beta- 2H1]Desoxypodophyllotoxin [3], [4 alpha- 2H1]desoxypodophyllotoxin [4], and [4, 4- 2 H2]desoxypodophyllotoxin [9] were prepared from podophyllotoxin [1] via its chloride [5]. A complete assignment of the 1H-nmr spectrum of desoxypodophyllotoxin [2] was made on the basis of the spectra of the deuterated compounds [3] and [4].

Pullockaran, A. J.; Kingston, D. G.; Lewis, N. G.

1989-01-01

432

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

E-print Network

were self-supporting and thermally stable up to 180 °C. Evaluation of proton conductivity as a function having proton conductivity comparable to uncrosslinked, liquid-like 1H-1,2,3-triazole functionalized of a proton exchange membrane with high mechanical strength, thermal, chemical and electrochemical stability

433

Human phase response curve to a 1 h pulse of bright white light  

PubMed Central

The phase resetting response of the human circadian pacemaker to light depends on the timing of exposure and is described by a phase response curve (PRC). The current study aimed to construct a PRC for a 1 h exposure to bright white light (?8000 lux) and to compare this PRC to a <3 lux dim background light PRC. These data were also compared to a previously completed 6.7 h bright white light PRC and a <15 lux dim background light PRC constructed under similar conditions. Participants were randomized for exposure to 1 h of either bright white light (n= 18) or <3 lux dim background light (n= 18) scheduled at 1 of 18 circadian phases. Participants completed constant routine (CR) procedures in dim light (<3 lux) before and after the light exposure to assess circadian phase. Phase shifts were calculated as the difference in timing of dim light melatonin onset (DLMO) during pre- and post-stimulus CRs. Exposure to 1 h of bright white light induced a Type 1 PRC with a fitted peak-to-trough amplitude of 2.20 h. No discernible PRC was observed in the <3 lux dim background light PRC. The fitted peak-to-trough amplitude of the 1 h bright light PRC was ?40% of that for the 6.7 h PRC despite representing only 15% of the light exposure duration, consistent with previous studies showing a non-linear duration–response function for the effects of light on circadian resetting. PMID:22547633

St Hilaire, Melissa A; Gooley, Joshua J; Khalsa, Sat Bir S; Kronauer, Richard E; Czeisler, Charles A; Lockley, Steven W

2012-01-01

434

Subcellular In Vivo 1 H MR Spectroscopy of Xenopus laevis Oocytes  

E-print Network

Subcellular In Vivo 1 H MR Spectroscopy of Xenopus laevis Oocytes Seung-Cheol Lee,* Jee-Hyun Cho voxel sizes of (180 mm)3 . In the large oocytes of the frog Xenopus laevis, this was small enough) microscopic imaging of a large single cell, the Xenopus laevis oocyte whose di- ameter is ;1.2 mm. Since then

Hammerton, James

435

NMR resonance splitting of urea in stretched hydrogels: Proton exchange and 1H/2H isotopologues  

NASA Astrophysics Data System (ADS)

Urea at ?12 M in concentrated gelatin gel, that was stretched, gave 1H and 2H NMR spectral splitting patterns that varied in a predictable way with changes in the relative proportions of 1H2O and 2H2O in the medium. This required consideration of the combinatorics of the two amide groups in urea that have a total of four protonation/deuteration sites giving rise to 16 different isotopologues, if all the atoms were separately identifiable. The rate constant that characterized the exchange of the protons with water was estimated by back-transformation analysis of 2D-EXSY spectra. There was no 1H NMR spectral evidence that the chiral gelatin medium had caused in-equivalence in the protons bonded to each amide nitrogen atom. The spectral splitting patterns in 1H and 2H NMR spectra were accounted for by intra-molecular scalar and dipolar interactions, and quadrupolar interactions with the electric field gradients of the gelatin matrix, respectively.

Kuchel, Philip W.; Naumann, Christoph; Chapman, Bogdan E.; Shishmarev, Dmitry; Håkansson, Pär; Bacskay, George; Hush, Noel S.

2014-10-01

436

NMR resonance splitting of urea in stretched hydrogels: proton exchange and (1)H/(2)H isotopologues.  

PubMed

Urea at ?12 M in concentrated gelatin gel, that was stretched, gave (1)H and (2)H NMR spectral splitting patterns that varied in a predictable way with changes in the relative proportions of (1)H2O and (2)H2O in the medium. This required consideration of the combinatorics of the two amide groups in urea that have a total of four protonation/deuteration sites giving rise to 16 different isotopologues, if all the atoms were separately identifiable. The rate constant that characterized the exchange of the protons with water was estimated by back-transformation analysis of 2D-EXSY spectra. There was no (1)H NMR spectral evidence that the chiral gelatin medium had caused in-equivalence in the protons bonded to each amide nitrogen atom. The spectral splitting patterns in (1)H and (2)H NMR spectra were accounted for by intra-molecular scalar and dipolar interactions, and quadrupolar interactions with the electric field gradients of the gelatin matrix, respectively. PMID:25241007

Kuchel, Philip W; Naumann, Christoph; Chapman, Bogdan E; Shishmarev, Dmitry; Håkansson, Pär; Bacskay, George; Hush, Noel S

2014-10-01

437

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

E-print Network

It is well known that generic two-Higgs-doublet models (2HDMs) suffer from potentially large Higgs-mediated flavor-changing neutral current (FCNC) problem, unless additional symmetries are imposed on the Higgs fields thereby respecting the Natural Flavor Conservation Criterion (NFC) by Glashow and Weinberg. A common way to respect the NFC is to impose Z_2 symmetry which is softly broken by a dim-2 operator. Another new way is to introduce local U(1)_H Higgs flavor symmetry that distinguish one Higgs doublet from the other. In this paper, we consider the Higgs phenomenology in Type-I 2HDMs with the U(1)_H symmetry with the simplest U(1)_H assignments that the SM fermions are all neutral under U(1)_H, and we make detailed comparison with the ordinary Type-I 2HDM. After imposing various constraints such as vacuum stability and perturbativity as well as the electroweak precision observables and collider search bounds on charged Higgs boson, we find that the allowed Higgs signal strengths in our model are much bro...

Ko, P; Yu, Chaehyun

2013-01-01

438

CALCIUM TRANSLOCATION IN THE AVIAN SHELL GLAND (1) H. SCHRAER Rosemary SCHRAER  

E-print Network

CALCIUM TRANSLOCATION IN THE AVIAN SHELL GLAND (1) H. SCHRAER Rosemary SCHRAER Department because of the large changes in calcium metabolism that occurred during the reproductive cycle on the movement of calcium across the shell gland of the domestic hen and some of the steps which led to this area

Boyer, Edmond

439

In vivo hyperpolarized 13C MR spectroscopic imaging with 1H decoupling.  

PubMed

Application of (13)C MRS in vivo on whole body MR system has been limited due to the low static field (and consequent low signal to noise ratio-SNR) of these scanners; thus there have been few reports of (1)H decoupled (13)C MRS in vivo using a clinical MR platform. The recent development of techniques to retain highly polarized spins in solution following DNP in a solid matrix has provided a mechanism to use endogenous pre-polarized (13)C labeled substrates to study real time cellular metabolism in vivo with high SNR. In a recent in vivo hyperpolarized metabolic imaging study using (13)C pyruvate, it has been demonstrated that the line shape (signal decay) of the resonances observed are greatly affected by J(CH) coupling in addition to inhomogeneous broadening. This study demonstrates the feasibility of improving hyperpolarized (13)C metabolic imaging in vivo by incorporating (1)H decoupling on a clinical whole body 3T MR scanner. No reduction of T1 of a pre-polarized (13)C substrate ([1-(13)C] lactate) in solution was observed when (1)H decoupling was applied with WALTZ16 sequence. Narrower linewidth for the [1-(13)C] lactate resonance was observed in hyperpolarized (13)C MRSI data in vivo with (1)H decoupling. PMID:19112035

Chen, Albert P; Tropp, James; Hurd, Ralph E; Van Criekinge, Mark; Carvajal, Lucas G; Xu, Duan; Kurhanewicz, John; Vigneron, Daniel B

2009-03-01

440

Intra-and Intermolecular Effects on 1 H Chemical Shifts in a Silk Model Peptide  

E-print Network

Intra- and Intermolecular Effects on 1 H Chemical Shifts in a Silk Model Peptide Determined by High peptide (Ala-Gly)15 for the crystalline domain of Bombyx mori silk fibroin in silk I and silk II structures, including a treatment of both intra- and intermolecular arrangements. Silk I and silk II

Williamson, Mike P.

441

Polarization quantum beat spectroscopy of HCF,,A~ 1 H hyperfine structure and Zeeman effect  

E-print Network

and Zeeman effect Haiyan Fan, Ionela Ionescu, Ju Xin,a) and Scott A. Reidb) Department of Chemistry investigate the 19 F and 1 H nuclear hyperfine structure and Zeeman effect in the simplest singlet carbene or Zeeman effect in this system, which are detailed probes of the elec- tronic structure and important

Reid, Scott A.

442

Documentation of ice shapes on the main rotor of a UH-1H helicopter in hover  

NASA Technical Reports Server (NTRS)

A helicopter icing flight test program in the hover mode was conducted with a UH-1H aircraft. The ice formations were documented after landing by means of silicone rubber molds, stereo photography and outline tracings for later use in aerodynamic analyses. The documentation techniques are described and the results presented for a typical flight.

Lee, J. D.; Harding, R.; Palko, R. L.

1984-01-01

443

Activation cross-sections of light ion induced nuclear reactions on platinum: proton induced reactions  

Microsoft Academic Search

Cross-sections of proton induced nuclear reactions on platinum were measured by using a standard stacked foil irradiation technique and high resolution gamma-ray spectroscopy. As a result experimental cross-sections and derived integral yields are reported from the respective threshold energy of the investigated reactions up to 70 MeV bombarding energy for the natPt(p,x)191,192,193,194,195,196m,g,196m2,198gAu, natPt(p,x)188,189,191,195Pt and natPt(p,x)188,189,190,192,194mIr