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  1. Phil Ochs: No Place in This World

    ERIC Educational Resources Information Center

    Doughty, Howard A.

    2005-01-01

    Phil Ochs was a prominent topical songwriter and singer in the 1960s. He was conventionally considered second only to Bob Dylan in terms of popularity, creativity and influence in the specific genre of contemporary folk music commonly known as "protest music." Whereas Dylan successfully reinvented himself many times in terms of his musical style…

  2. Atmospheric chemistry of CF3CF2OCH3

    NASA Astrophysics Data System (ADS)

    Østerstrøm, Freja F.; Nielsen, Ole John; Wallington, Timothy J.

    2016-06-01

    Smog chamber Fourier transform infrared techniques were used to investigate the kinetics of the reaction of CF3CF2OCH3 with Cl atoms and OH radicals: k(Cl + CF3CF2OCH3) = (1.09 ± 0.16) × 10-13 and k(OH + CF3CF2OCH3) = (1.28 ± 0.19) × 10-14 cm3 molecule-1 s-1 in 700 Torr total pressure of N2/O2 at 296 ± 2 K. The Cl-initiated oxidation of CF3CF2OCH3 gives CF3CF2OCHO in a yield indistinguishable from 100%. An estimate of k(Cl + CF3CF2OCHO) = (1.18 ± 0.34) × 10-14 cm3 molecule-1 s-1 is provided. Based on the OH reaction rate, the atmospheric lifetime of CF3CF2OCH3 is estimated to be 5.0 years. The 100-year time horizon global warming potential of CF3CF2OCH3 is estimated to be 585. The atmospheric impact of CF3CF2OCH3 is discussed.

  3. Water-soluble derivatives of 25-OCH3-PPD and their anti-proliferative activities.

    PubMed

    Zhou, Wu-Xi; Sun, Yuan-Yuan; Yuan, Wei-Hui; Zhao, Yu-Qing

    2017-03-18

    (20R)-25-Methoxyl-dammarane-3β,12β,20-triol (25-OCH3-PPD, AD-1) is a dammarane-type sapogenin showing anti-tumor potential. In the search for new anti-tumor agents with higher potency than our previously identified compound 25-OCH3-PPD, 11 novel sulfamic acid and diacid derivatives that could improve water solubility and contribute to good drug potency and pharmacokinetic profiles were designed and synthesized. Their in vitro anti-tumor activities in MCF-7, A-549, HCT-116, and BGC-823 cell lines and one normal cell line were tested by standard MTT assay. Results showed that compared with compound 25-OCH3-PPD, compounds 1, 4, and 5 exhibited higher cytotoxic activity on almost all cell lines, together with lower toxicity in the normal cell. In particular, compound 1 exhibited the best anti-tumor activity in the in vitro assays. The water solubility of 25-OCH3-PPD and its derivatives was tested and the results showed that the solubility of 25-OCH3-PPD sulfamic acid and diacid derivatives were better than that of 25-OCH3-PPD in water, which may provide valuable data for the research and development of new anti-tumor agents.

  4. Atmospheric degradation mechanism of CF{sub 3}OCH{sub 3}

    SciTech Connect

    Christensen, L.K.; Wallington, T.J.; Guschin, A.; Hurley, M.D.

    1999-05-27

    Recognition of the adverse effect of chlorofluorocarbon (CFC) release into the atmosphere has led to an international effort to replace CFCs with environmentally acceptable alternatives. Hydrofluoroethers (HFEs) are a class of compounds which have been developed to replace CFCs in applications such as the cleaning of electronic equipment, heat transfer agents in refrigeration systems, and carrier fluids for lubricant deposition. HFEs are volatile compounds and are released into the atmosphere when used. CF{sub 3}OCH{sub 3} has not been used commercially but is one of the simplest fluoroethers and serves as a model compound for the group of fluorinated ethers. A smog chamber/FTIR technique was used to study the Cl atom initiated oxidation of CF{sub 3}OCH{sub 3} in 700 Torr of N{sub 2}/O{sub 2} at 296 K. Using relative rate techniques it was determined that {kappa}(Cl + CF{sub 3}OCH{sub 3}) = (1.4 {+-} 0.2) {times} 10{sup {minus}13} and {kappa}(Cl + CF{sub 3}OC(O)H) = (9.8 {+-} 1.2) {times} 10{sup {minus}15} cm{sup 3} molecule{sup {minus}1} s{sup {minus}1}. At 700 Torr of N{sub 2}/O{sub 2} diluent at 296 K reaction with O{sub 2} is the only loss mechanism of the CF{sub 3}OCH{sub 2}O{sup {sm_bullet}} radical. The infrared spectra of the peroxy nitrates CF{sub 3}OCH{sub 2}O{sub 2}NO{sub 2} and CF{sub 3}OC(O)O{sub 2}NO{sub 2} were recorded and compared to the nonfluorinated analogues CH{sub 3}OCH{sub 2}O{sub 2}NO{sub 2} and CH{sub 3}OC(O)O{sub 2}NO{sub 2}. The thermal decomposition rate of CF{sub 3}OC(O)NO{sub 2} is (2.3 {+-} 0.1) {times} 10{sup {minus}4} s{sup {minus}1} in 700 Torr of N{sub 2} at 295.8 K. The reaction of CF{sub 3}OC(O)O{sub 2} radicals with HO{sub 2} radicals gives CF{sub 3}OC(O)H in a yield of (80 {+-} 11)%. The results are discussed with respect to the atmospheric degradation mechanism of CF{sub 3}OCH{sub 3} and other ethers.

  5. Study and orientation of the Mt. Oche `Dragon House' in Euboea, Greece

    NASA Astrophysics Data System (ADS)

    Theodossiou, E.; Manimanis, V. N.; Katsiotis, M.; Papanikolaou, D.

    2009-07-01

    In southern Euboea, Central Greece, there are several megalithic buildings known as ‘drakospita’ (or dragon houses) whose builders and purpose are unknown. On 22 March 2002 and 4 July 2004 we visited the bestpreserved of all drakospita on top of Mt. Oche, measured its dimensions and calculated its orientation based on the azimuth of sunset and moonrise. A Sirius-rise orientation corresponding to ca 1100 B.C., not inconsistent with previous archaeological dating based on artefacts found inside the structure, indicates a religious/astronomical purpose for the building. It could probably be argued that at least the famous drakospito at Mt. Oche was not only a place of worship but also an ancient astronomical observatory.

  6. The ether lipid ET-18-OCH3 increases cytosolic Ca2+ concentrations in Madin Darby canine kidney cells.

    PubMed

    Jan, C R; Wu, S N; Tseng, C J

    1999-07-01

    The effect of the ether lipid 1-O-octadecyl-2-O-methyl-sn-glycero-3-phosphorylcholine (ET-18-OCH3) on the intracellular free Ca2+ concentration ([Ca2+]i) in Madin Darby canine kidney (MDCK) cells was studied using fura-2 as the Ca2+ probe. In Ca2+ medium, ET-18-OCH3 induced a significant rise in [Ca2+]i at concentrations between 10-100 microM with a concentration-dependent delay of 45-175 s. The [Ca2+]i signal was composed of a gradual rise and a sustained plateau. In Ca2+-free medium, ET-18-OCH3 (10-100 microM) induced a Ca2+ release from internal Ca2+ stores with a concentration-dependent delay of 45-175 s. This discharge of internal Ca2+ triggered capacitative Ca2+ entry in a concentration-dependent manner. This capacitative Ca2+ entry was not inhibited by econazole (25 microM), 1-[beta-[3-(4-methoxyphenyl)propoxy]-4-methoxyphenethyl]-1H-imidazole hydrochloride (SKF96365; 50 microM), nifedipine (10 microM), verapamil (10 microM), diltiazem (10 microM) and cadmium (0.5 microM). Methyl 2-(phenylthio)ethyl-1,4-dihydro-2,4,6-trimethylpyridine-3,5-dicarboxylat e (PCA-4248), a platelet-activating factor (PAF) receptor antagonist, inhibited 25 microM ET-18-OCH3-induced [Ca2+]i rise in a concentration-dependent manner between 1-20 microM, with 20 microM exerting a complete block. The [Ca2+]i rise induced by ET-18-OCH3 (25 microM) was not altered when the production of inositol 1,4,5-trisphosphate (IP3) was suppressed by the phospholipase C inhibitor U73122 (2 microM), but was partly inhibited by the phospholipase D inhibitor propranolol (0.1 mM) or the phospholipase A2 inhibitor aristolochic acid (20-40 microM). In Ca2+-free medium, pretreatment with 25 microM ET-18-OCH3 completely depleted the endoplasmic reticulum Ca2+ pump inhibitor thapsigargin-sensitive Ca2+ store. In contrast, pretreatment with thapsigargin abolished 0.1 mM ATP-induced [Ca2+]i rise without altering the ET-18-OCH3-induced [Ca2+]i rise. This suggests that ET-18-OCH3 depleted thapsigargin

  7. Phage resistance of a marine bacterium, Roseobacter denitrificans OCh114, as revealed by comparative proteomics.

    PubMed

    Huang, Chunxiao; Zhang, Yongyu; Jiao, Nianzhi

    2010-08-01

    Roseobacter is a dominant lineage in the marine environment. This group of bacteria is diverse in terms of both their phylogenetic composition and their physiological potential. Roseobacter denitrificans OCh114 is one of the most studied bacteria of the Roseobacter lineage. Recently, a lytic phage (RDJLPhi1) that infects this bacterium was isolated and a mutant strain (M1) of OCh114 that is resistant to RDJLPhi1 was also obtained. Here, we investigate the mechanisms supporting phage resistance of M1. Our results excluded the possibilities of several phage resistance mechanisms, including abortive infection, lysogeny, and the clustered regularly interspaced short palindromic repeats (CRISPRs) related mechanism. Adsorption kinetics assays revealed that adsorption inhibition might be a potential cause for the phage resistance of M1. Comparative proteomic analysis of M1 and OCh114 revealed significant changes in the membrane protein compliment of these bacteria. Five membrane proteins with important biological functions were significantly down-regulated in the phage-resistant M1. Meanwhile, several outer membrane porins with different modifications and an OmpA family domain protein were markedly up-regulated. We hypothesize that the down-regulated membrane proteins in M1 may serve as the potential phage receptors, whose absence prevented the adsorption of phage RDJLPhi1 to host cells and subsequent infection.

  8. Natural product ginsenoside 25-OCH3-PPD inhibits breast cancer growth and metastasis through down-regulating MDM2.

    PubMed

    Wang, Wei; Zhang, Xu; Qin, Jiang-Jiang; Voruganti, Sukesh; Nag, Subhasree Ashok; Wang, Ming-Hai; Wang, Hui; Zhang, Ruiwen

    2012-01-01

    Although ginseng and related herbs have a long history of utility for various health benefits, their application in cancer therapy and underlying mechanisms of action are not fully understood. Our recent work has shown that 20(S)-25-methoxyl-dammarane-3β, 12β, 20-triol (25-OCH(3)-PPD), a newly identified ginsenoside from Panax notoginseng, exerts activities against a variety of cancer cells in vitro and in vivo. This study was designed to investigate its anti-breast cancer activity and the underlying mechanisms of action. We observed that 25-OCH(3)-PPD decreased the survival of breast cancer cells by induction of apoptosis and G1 phase arrest and inhibited the growth of breast cancer xenografts in vivo. We further demonstrated that, in a dose- and time-dependent manner, 25-OCH(3)-PPD inhibited MDM2 expression at both transcriptional and post-translational levels in human breast cancer cells with various p53 statuses (wild type and mutant). Moreover, 25-OCH(3)-PPD inhibited in vitro cell migration, reduced the expression of epithelial-to-mesenchymal transition (EMT) markers, and prevented in vivo metastasis of breast cancer. In summary, 25-OCH(3)-PPD is a potential therapeutic and anti-metastatic agent for human breast cancer through down-regulating MDM2. Further preclinical and clinical development of this agent is warranted.

  9. A General Method for Imine Formation Using B(OCH2CF3)3.

    PubMed

    Reeves, Jonathan T; Visco, Michael D; Marsini, Maurice A; Grinberg, Nelu; Busacca, Carl A; Mattson, Anita E; Senanayake, Chris H

    2015-05-15

    Tris(2,2,2-trifluoroethyl)borate [B(OCH2CF3)3] was found to be a mild and general reagent for the formation of a variety of imines by condensation of amides or amines with carbonyl compounds. N-Sulfinyl, N-toluenesulfonyl, N-(dimethylamino)sulfamoyl, N-diphenylphosphinoyl, N-(α-methylbenzyl), and N-(4-methoxyphenyl) aldimines are all accessible using this reagent at room temperature. The reactions are operationally simple, and the products are obtained without special workup or isolation procedures.

  10. Comparison Of Several Metrology Techniques For In-line Process Monitoring Of Porous SiOCH

    SciTech Connect

    Fossati, D.; Imbert, G.; Beitia, C.; Yu, L.; Plantier, L.; Volpi, F.

    2007-09-26

    As porous SiOCH is a widely used inter-metal dielectric for 65 nm nodes and below, the control of its elaboration process by in-line monitoring is necessary to guarantee successful integration of the material. In this paper, the sensitivities of several non-destructive metrology techniques towards the film elaboration process drifts are investigated. It appears that the two steps of the process should be monitored separately and that corona charge method is the most sensitive technique of the review for this application.

  11. Disproportionation and thermochemical sulfate reduction reactions in S-H2O-CH4 and S-D2O-CH4 systems from 200 to 340 °C at elevated pressures

    NASA Astrophysics Data System (ADS)

    Yuan, Shunda; Chou, I.-Ming; Burruss, Robert C.

    2013-10-01

    Elemental sulfur, as a transient intermediate compound, by-product, or catalyst, plays significant roles in thermochemical sulfate reduction (TSR) reactions. However, the mechanisms of the reactions in S-H2O-hydrocarbons systems are not clear. To improve our understanding of reaction mechanisms, we conducted a series of experiments between 200 and 340 °C for S-H2O-CH4, S-D2O-CH4, and S-CH4-1m ZnBr2 systems in fused silica capillary capsules (FSCCs). After a heating period ranging from 24 to 2160 h (hrs), the quenched samples were analyzed by Raman spectroscopy. Combined with the in situ Raman spectra collected at high temperatures and pressures in the S-H2O and S-H2O-CH4 systems, our results showed that (1) the disproportionation of sulfur in the S-H2O-CH4 system occurred at temperatures above 200 °C and produced H2S, SO42-, and possibly trace amount of HSO4-; (2) sulfate (and bisulfate), in the presence of sulfur, can be reduced by methane between 250 and 340 °C to produce CO2 and H2S, and these TSR temperatures are much closer to those of the natural system (<200 °C) than those of any previous experiments; (3) the disproportionation and TSR reactions in the S-H2O-CH4 system may take place simultaneously, with TSR being favored at higher temperatures; and (4) in the system S-D2O-CH4, both TSR and the competitive disproportionation reactions occurred simultaneously at temperatures above 300 °C, but these reactions were very slow at lower temperatures. Our observation of methane reaction at 250 °C in a laboratory time scale suggests that, in a geologic time scale, methane may be destroyed by TSR reactions at temperatures >200 °C that can be reached by deep drilling for hydrocarbon resources.

  12. The mechanism of low-k SiOCH film modification by oxygen atoms

    SciTech Connect

    Braginsky, O. V.; Kovalev, A. S.; Lopaev, D. V.; Malykhin, E. M.; Mankelevich, Yu. A.; Rakhimova, T. V.; Rakhimov, A. T.; Vasilieva, A. N.; Zyryanov, S. M.; Baklanov, M. R.

    2010-10-15

    The interaction of oxygen atoms with three types of plasma enhanced chemical vapor deposition low-k SiOCH films is studied. The samples were treated by O atoms in the far plasma afterglow conditions in a special experimental system designed for this study. The experimental system allowed avoiding the effect of ions and vacuum ultraviolet (VUV) photons on surface reactions and controlling the oxygen atom concentration over the samples. Fourier-transform infrared spectroscopy, x-ray fluorescence, and atomic force microscopy techniques were used to analyze the changes occurring in low-k films. Monte Carlo model for O atom interaction with low-k material that includes penetration, recombination, and reactions with methyl groups was developed. It is shown that the surface recombination on the pore wall surface determines the profile and penetration depth of O atoms into the films. The reaction of O atoms with methyl groups has lower probability and therefore proceeds in the background mode.

  13. Theoretical study and rate constant calculation of the CH2O+CH3 reaction

    NASA Astrophysics Data System (ADS)

    Liu, Jing-yao; Li, Ze-sheng; Wu, Jia-yan; Wei, Zhi-gang; Zhang, Gang; Sun, Chia-chung

    2003-10-01

    The potential energy surface of the CH2O+CH3 reaction is explored at the MP2/6-311++G(d,p), MP4SDQ/6-311G(d,p), and QCISD(T)/6-311+G(3df,2p) (single point) levels of theory. Theoretical calculations suggest that the major product channel (R1) is the hydrogen abstraction leading to the product P1 CHO+CH4 (R1), while the addition process leading to P2H+CH3CHO (R2) appears to be negligibly small. The calculated enthalpies and dissociation activation energies for CH3CH2O and CH3OCH2 radicals involved in the reaction are in line with the experimental values. Dual-level dynamics calculation is carried out for the direct hydrogen abstraction channel. The energy profile of (R1) is refined with the interpolated single-point energies (ISPE) method at the QCISD(T)//MP2 level. The rate constants, which are evaluated by canonical variational transition-state theory (CVT) including small-curvature tunneling (SCT) correction, are in good agreement with the available experimental data. It is shown that tunneling effect plays a significant role in the rate constant calculation; and as a result, the CVT/SCT rate constants exhibit typical non-Arrhenius behavior over a wide temperature range 300-2000 K. The three parameter expression is k=6.35×10-26 T4.4 exp(-2450/T) cm3 molecule-1 s-1.

  14. Analysis of the Pressure and Temperature Dependence of the Complex-Forming Bimolecular Reaction CH3OCH3 + Fe(.).

    PubMed

    Ard, Shaun G; Johnson, Ryan S; Martinez, Oscar; Shuman, Nicholas S; Guo, Hua; Troe, Jürgen; Viggiano, Albert

    2016-07-14

    The kinetics of the reaction CH3OCH3 + Fe(+) has been studied between 250 and 600 K in the buffer gas He at pressures between 0.4 and 1.6 Torr. Total rate constants and branching ratios for the formation of Fe(+)O(CH3)2 adducts and of Fe(+)OCH2 + CH4 products were determined. Quantum-chemical calculations provided the parameters required for an analysis in terms of statistical unimolecular rate theory. The analysis employed a recently developed simplified representation of the rates of complex-forming bimolecular reactions, separating association and chemical activation contributions. Satisfactory agreement between experimental results and kinetic modeling was obtained that allows for an extrapolation of the data over wide ranges of conditions. Possible reaction pathways with or without spin-inversion are discussed in relation to the kinetic modeling results.

  15. Atmospheric chemistry of CF{sub 3}C(O)OCH{sub 2}CF{sub 3}: UV spectra and kinetic data for CF{sub 3}C(O)OCH({sm_bullet})CF{sub 3} and CF{sub 3}C(O)OCH(OO{sm_bullet})CF{sub 3} radicals, and atmospheric fate of CF{sub 3}C(O)OCH(O{sm_bullet})CF{sub 3} radicals

    SciTech Connect

    Stein, T.N.N.; Christensen, L.K.; Platz, J.; Sehested, J.; Nielsen, O.J.; Wallington, T.J.

    1999-07-22

    Recognition of the adverse effect of chlorofluorocarbon (CFC) release into the atmosphere has led to an international effort to replace CFCs with environmentally acceptable alternatives. Hydrofluoroethers (HFEs) are fluids designed to replace CFCs in applications such as the cleaning of electronic equipment, heat transfer agents in refrigeration systems, and carrier fluids for lubricant deposition. HFEs are volatile compounds and will be released into the atmosphere during its use. In the atmosphere, photochemical oxidation of HFEs will lead to the formation of fluorinated esters and fluorinated formates. The atmospheric fate of these products is unknown at the present. To improve their understanding of the atmospheric chemistry of esters the authors have studied the atmospheric chemistry of 2,2,2-trifluoroethyltrifluoroacetate CF{sub 3}C(O)OCH{sub 2}CF{sub 3} (bp = 55.0 C). This compound provides insight into the behavior of alkyl, alkyl peroxy, and alkoxy radicals formed {alpha} to the ester functionality. The atmospheric fate of CF{sub 3}C(O)OCH(O{sup {sm_bullet}})CF{sub 3} radicals was investigated in a FTIR smog chamber. Three loss processes for the CF{sub 3}C(O)OCH(O{sup {sm_bullet}})CF{sub 3} radicals were identified at 296 K and 700 Torr total pressure, reaction with O{sub 2} to form CF{sub 3}C(O)OC(O)CF{sub 3}, {alpha}-rearrangement to form CF{sub 3}C(O){sm_bullet} radicals and CF{sub 3}C(O)OH, and decomposition via a mechanism which is unclear. In 760 Torr of air at 296 K, 65% of the CF{sub 3}C(O)OCH(O{sm_bullet})CF{sub 3} radicals react with oxygen, 18% undergo {alpha}-rearrangement, while the fate of the remaining 17% is unclear.

  16. Hydrogen and methanol exchange processes for (TMP)Rh-OCH3(CH3OH) in binary solutions of methanol and benzene.

    PubMed

    Sarkar, Sounak; Li, Shan; Wayland, Bradford B

    2011-04-18

    Tetramesityl porphinato rhodium(III) methoxide ((TMP)Rh-OCH(3)) binds with methanol in benzene to form a 1:1 methanol complex ((TMP)Rh-OCH(3)(CH(3)OH)) (1). Dynamic processes are observed to occur for the rhodium(III) methoxide methanol complex (1) that involve both hydrogen and methanol exchange. Hydrogen exchange between coordinated methanol and methoxide through methanol in solution results in an interchange of the environments for the non-equivalent porphyrin faces that contain methoxide and methanol ligands. Interchange of the environments of the coordinated methanol and methoxide sites in 1 produces interchange of the inequivalent mesityl o-CH(3) groups, but methanol ligand exchange occurs on one face of the porphyrin and the mesityl o-CH(3) groups remain inequivalent. Rate constants for dynamic processes are evaluated by full line shape analysis for the (1)H NMR of the mesityl o-CH(3) and high field methyl resonances of coordinated methanol and methoxide groups in 1. The rate constant for interchange of the inequivalent porphyrin faces is associated with hydrogen exchange between 1 and methanol in solution and is observed to increase regularly with the increase in the mole fraction of methanol. The rate constant for methanol ligand exchange between 1 and the solution varies with the solution composition and fluctuates in a manner that parallels the change in the activation energy for methanol diffusion which is a consequence of solution non-ideality from hydrogen bonded clusters.

  17. Towards understanding intrinsic degradation and breakdown mechanisms in SiOCH low-k dielectrics

    SciTech Connect

    Wu, C. De Wolf, I.; Li, Y.; Ciofi, I.; Kauerauf, Th.; Bömmels, J.; Tőkei, Zs.; Croes, K.

    2015-02-14

    The degradation and breakdown mechanisms of a SiOCH low-k material with k = 2.3 (25% porosity) and thicknesses ranging from 90 nm to 20 nm were investigated. By combining the time dependent dielectric breakdown data at positive/negative bias stress with the thickness scaling results, dielectric failure is proven to be intrinsic and not influenced by copper drift or metal barrier deposition induced dielectric damage. It is shown that stress induced leakage current (SILC) can be used as a measure of dielectric degradation. Therefore, low field lifetimes can be safely estimated using SILC extrapolation. Based on our results, both the impact damage model and the power law model have a good accuracy for low field lifetime prediction. Recovery and anneal experiments are used to study the physical nature causing the observed negative flatband voltage shifts in our metal-insulator-semiconductor planar capacitor structures, where hydrogen induced unstable fast and slow donor type interface states are hypothesized to be the root cause of the observed shifts. We suggest that atomic hydrogen is released from the dielectric during electron injection and migrates to the interfacial region. Our model is further supported by an observed irreversible SILC change during the recovery and anneal studies. The degradation mechanism proposed in this work, supported by the low field lifetime data, provides a feasible explanation for intrinsic low-k dielectric failure.

  18. Astronomical Orientations Of Dragon Houses (Laka Palli, Kapsala, Oche) And Armena Gate (Euboea, Greece)

    NASA Astrophysics Data System (ADS)

    Liritzis, I.; Artelaris, G.

    The preliminary investigation of the astronomical orientation of monuments at Styra, southern Euboea, includes the triple so called 'dragon house' complex at Laka Palli, one dragon house at Kapsala and one on the summit of Mount Oche, and a monumental gate in the megalithic fortification wall at Armena. Recent luminescence testing dates these remains to approximately the Classical period with apparent re-use in Roman and later times. Thus far no definite astronomical orientation has been determined in the layout of the structures and no celestial stone markers or similar features have been found associated with the dragon houses, however, the relationship of significant stars, constellations and solar stands was well known in antiquity, and the limited results presented here suggests the possibility for further investigation. This study, which considered possible orientations related to sun rise and sun set for the summer and winter solstice, as well as, alignments towards equinoxes and major bright stars and constellations, did observe a general preference for a southern orientation at most of the sites and a possible feature for time observations in the dragon house complex at Laka Palli.

  19. High pressure Raman spectroscopy of H2O-CH3OH mixtures.

    PubMed

    Hsieh, Wen-Pin; Chien, Yu-Hsiang

    2015-02-23

    Complex intra-molecular interactions and the hydrogen-bonding network in H2O-volatile mixtures play critical roles in many dynamics processes in physical chemistry, biology, and Earth and planetary sciences. We used high pressure Raman spectroscopy to study the pressure evolution of vibrational frequencies and bonding behavior in H2O-CH3OH mixtures. We found that the presence of low CH3OH content in H2O increases the transition pressure where water crystallizes to ice VI, but does not significantly change the pressure where ice VI transforms to ice VII. Furthermore, the stiffening rates of C-H stretching frequencies dω/dP in CH3OH significantly decrease upon the crystallization of water, and the softening rates of the O-H stretching frequencies of ice VII are suppressed over a narrow pressure range, after which the frequencies of these modes shift with pressure in ways similar to pure CH3OH and ice VII, respectively. Such complex pressure evolution of Raman frequencies along with pronounced variations in Raman intensities of CH3OH within the sample, and the hysteresis of the water-ice VI phase transition suggest pressure-induced segregation of low content CH3OH from ice VII. These findings indicate the significant influence of volatiles on the crystallization of sub-surface ocean and thermal evolution within large icy planets and satellites.

  20. Disproportionation and Thermochemical Sulfate Reduction Reactions in S-H2O-CH4 and S-D2O-CH4 Systems from 200 to 340 °C at Elevated Pressures

    NASA Astrophysics Data System (ADS)

    Chou, I.; Yuan, S.; Burruss, R. C.

    2010-12-01

    Elemental sulfur plays significant roles in thermochemical sulfate reduction (TSR) reactions as a transient intermediate oxidation state compound, by-product, or catalyst. However, the mechanisms of the reactions in S-H2O-hydrocarbon systems are not clear. To improve our understanding of reaction mechanisms, we conducted a series of experiments between 200 and 340 °C for S-H2O-CH4, S-D2O-CH4, and S-CH4-1m ZnBr2 systems in fused silica capillary capsules. After a heating period ranging from one to 90 days, the quenched samples were analyzed by Raman spectroscopy. Our results showed that the disproportionation of sulfur in the S-H2O-CH4 system occurred at temperatures above 200 °C and produced H2S, SO42-, and HSO4-. We also observed that the amounts of SO42- and HSO4- decreased for the samples quenched from 250 and 340 °C, and at the same time the amounts of CO2 and H2S increased. To demonstrate that the observed consumption of SO42- and HSO4- in the S-H2O-CH4 system at 300 °C was due to TSR instead of the back reaction between SO42- (or HSO4-) and H2S to form S during and after quench, we introduced 1m ZnBr2 to remove H2S as a ZnS precipitate, as soon as it formed. In these experiments sulfate species decreased and CO2 and H2S increased consistent with TSR and no back reaction. When compared with previously published experiments, our temperatures between 250 and 340 °C are much closer to natural systems (<200 °C) with documented TSR. Also, to demonstrate the relationship between disproportionation and TSR reactions in the S-H2O-CH4 system, we conducted experiments in the S-D2O-CH4 system at 250 and 300 °C. Only small Raman signals for CO2 and no signals for H2S and D2S were detected in the sample quenched from 250 °C, indicating that both the disproportionation reaction and the TSR reaction were very slow at this temperature. After heating at 300 °C for 40 h, Raman signals of the quenched sample indicated significant amount of D2S was produced through the

  1. Investigation of the O+allyl addition/elimination reaction pathways from the OCH2CHCH2 radical intermediate

    NASA Astrophysics Data System (ADS)

    Fitzpatrick, Benjamin L.; Lau, Kai-Chung; Butler, Laurie J.; Lee, Shih-Huang; Lin, Jim-Min, Jr.

    2008-08-01

    These experiments study the preparation of and product channels resulting from OCH2CHCH2, a key radical intermediate in the O+allyl bimolecular reaction. The data include velocity map imaging and molecular beam scattering results to probe the photolytic generation of the radical intermediate and the subsequent pathways by which the radicals access the energetically allowed product channels of the bimolecular reaction. The photodissociation of epichlorohydrin at 193.3 nm produces chlorine atoms and c-OCH2CHCH2 radicals; these undergo a facile ring opening to the OCH2CHCH2 radical intermediate. State-selective resonance-enhanced multiphoton ionization (REMPI) detection resolves the velocity distributions of ground and spin-orbit excited state chlorine independently, allowing for a more accurate determination of the internal energy distribution of the nascent radicals. We obtain good agreement detecting the velocity distributions of the Cl atoms with REMPI, vacuum ultraviolet (VUV) photoionization at 13.8 eV, and electron bombardment ionization; all show a bimodal distribution of recoil kinetic energies. The dominant high recoil kinetic energy feature peaks near 33 kcal/mol. To elucidate the product channels resulting from the OCH2CHCH2 radical intermediate, the crossed laser-molecular beam experiment uses VUV photoionization and detects the velocity distribution of the possible products. The data identify the three dominant product channels as C3H4O (acrolein)+H, C2H4+HCO (formyl radical), and H2CO (formaldehyde)+C2H3. A small signal from C2H2O (ketene) product is also detected. The measured velocity distributions and relative signal intensities at m/e=27, 28, and 29 at two photoionization energies show that the most exothermic product channel, C2H5+CO, does not contribute significantly to the product branching. The higher internal energy onset of the acrolein+H product channel is consistent with the relative barriers en route to each of these product channels

  2. Hydrogen isotope systematics of H2-H2O-CH4 during hydrogenotrophic methanogenesis

    NASA Astrophysics Data System (ADS)

    Kobayashi, M.; Kawagucci, S.; Hattori, S.; Yamada, K.; Ueno, Y.; Takai, K.; Yoshida, N.

    2011-12-01

    Hydrogen and carbon isotopes of CH4 have been utilized to trace microbial processes. The isotope fractionations during hydrogenotrophic methanogenesis, one of the major processes of environmental CH4, have been studied by several laboratory incubations. For the carbon isotope, H2 concentration is thought to be the major parameter controlling the carbon isotope fractionation by hydrogenotrophic methanogenesis. For the hydrogen, on the other hand, factors controlling isotope fractionation remain poorly understood, although H2 concentration is suggested to be important. This uncertainty prevents us to utilize δD-CH4 value as the tracer. The most important and principal question is whether all hydrogen atoms in microbially-generated CH4 come from environmental H2O or not. To answer the question, we investigated the D/H systematics of H2-H2O-CH4 during hydrogenotrophic methanogenesis by pure culture incubation with softly deuterium-enriched H2 and/or H2O. Our results demonstrate that δD-CH4 value produced by hydrogenotrophic methanogens depends not only on δD-H2O value but also on δD-H2 value. We observed constant correlation between δD-H2 and δD-CH4 values as well as between δD-H2O and δD-CH4 values, which suggests that hydrogen (/deuterium) atom of substrate H2 is also transferred to the product CH4. This implies that the range of δD-CH4 value produced by hydrogenotrophic methanogenesis should be re-evaluated considering the distribution of δD-H2 and δD-H2O values in natural environments.

  3. Long persistent near infrared luminescence nanoprobes LiGa5O8:Cr3+-PEG-OCH3 for in vivo imaging

    NASA Astrophysics Data System (ADS)

    Fu, Xiaoyan; Liu, Chunlin; Shi, Junpeng; Man, Huizi; Xu, Jia; Zhang, Hongwu

    2014-09-01

    The Cr3+-doped LiGa5O8 nanoparticles (LGNPs) with long-persistent near-infrared phosphorescence were obtained through a sol-gel approach followed by heat treatment at 800 °C in air. The obtained results reveal that the nanoparticles with an average diameter of 100 nm are well defined and have pure structure of LiGa5O8. After illumination for 3 min using a 254 nm UV lamp, the LGNPs exhibit strong near-infrared peak at ca. 720 nm belonging to tissue transparency window which can last for more than 1 h. Via surface modified with PEG-5000-OCH3, the LGNPs-PEG-OCH3 exhibit excellent biocompatibility and low toxicity. Under in vitro pre-excitation using a 254 nm UV lamp for 3 min, the in vivo distribution of the LGNPs-PEG-OCH3 in the abdomen can be detected in real time for more than 1 h. All the results indicate that the LGNPs-PEG-OCH3 can be used as potential nanoprobes to realize in vivo, real time and long time imaging with high sensitivity.

  4. Induction of apoptosis in human mitogen-activated peripheral blood T-lymphocytes by the ether phospholipid ET-18-OCH3: Involvement of the Fas receptor/ligand system

    PubMed Central

    Cabaner, Christelle; Gajate, Consuelo; Macho, Antonio; Muñoz, Eduardo; Modolell, Manuel; Mollinedo, Faustino

    1999-01-01

    Activated T-cells constitute a target for treatment of autoimmune diseases. We have found that the antitumour ether phospholipid 1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine (ET-18-OCH3; edelfosine) induced dose- and time-dependent apoptosis in human mitogen-activated peripheral blood T-lymphocytes, but not in resting T-cells. T-lymphocytes were stimulated with phytohemagglutinin and interleukin-2 or with concanavalin A. Apoptosis was assessed by DNA fragmentation through cell cycle and TUNEL analyses, as well as through visualization of internucleosomal DNA fragmentation in agarose gels.The ET-18-OCH3-mediated apoptotic response in activated T-lymphocytes was less intense than in human leukaemic T cell lines, such as Jurkat cells and Peer cells; namely about 25% apoptosis in activated T-cells versus about 46–61% apoptosis in T leukaemic cells after 24 h treatment with 10 μM ET-18-OCH3.The ET-18-OCH3 thioether analogue BM 41.440 (ilmofosine) showed a similar apoptotic capacity to that found with ET-18-OCH3 in activated T-cells, whereas the phospholipid analogue hexadecylphosphocholine (miltefosine) failed to promote this response.The uptake of [3H]-ET-18-OCH3 was much larger in activated T-cells than in resting lymphocytes.Using a cytofluorimetric approach we have found that ET-18-OCH3 induced disruption of the mitochondrial transmembrane potential and production of reactive oxygen species in activated T-cells, but not in resting lymphocytes.ET-18-OCH3 induced an increase in Fas (APO-1/CD95) ligand mRNA expression in activated T-cells, and incubation with a blocking anti-Fas (APO-1/CD95) antibody partially inhibited the ET-18-OCH3-induced apoptosis of activated T-lymphocytes.These results demonstrate that mitogen-activated T-cells, unlike resting lymphocytes, are able to take up significant amounts of ET-18-OCH3, and are susceptible to undergo apoptosis by the ether lipid via, in part, the Fas (APO-1/CD95) receptor/ligand system. This ET-18-OCH3

  5. A single-molecule magnet featuring a parallelogram [Dy4(OCH2-)4] core and two magnetic relaxation processes.

    PubMed

    Liu, Cai-Ming; Zhang, De-Qing; Zhu, Dao-Ben

    2013-10-01

    An alkoxido-bridged tetranuclear Dy(iii) complex, [Dy4(H3L)2(OAc)6]·2EtOH {, H6L = 1,3-bis[tris(hydroxymethyl)methylamino]propane}, has been solvothermally synthesized and characterized. An X-ray crystallographic study revealed that complex possesses a novel "parallelogram" [Dy4(OCH2-)4] core, and a new binding mode η(3):η(3):η(1):η(1):η(1):η(2):μ(4) of the Bis-tris propane ligand was observed. Magnetic investigations indicated that it is a single-molecule magnet (SMM), showing two distinct magnetic relaxation processes with the energy barriers of 44 K and 107 K, respectively. Such a two-step magnetic relaxation process could be well described by the sum of two modified Debye functions.

  6. Damage by radicals and photons during plasma cleaning of porous low-k SiOCH. II. Water uptake and change in dielectric constant

    SciTech Connect

    Shoeb, Juline; Kushner, Mark J.

    2012-07-15

    Porous dielectric materials provide lower capacitances that reduce RC time delays in integrated circuits. Typical low-k materials include porous SiOCH-silicon dioxide with carbon groups, principally CH{sub 3}, lining the pores. With a high porosity, internally connected pores provide pathways for reactive species to enter into the material. Fluorocarbon plasmas are often used to etch SiOCH, a process that leaves a fluorocarbon polymer on the surface that must later be removed. During cleaning using Ar/O{sub 2} or He/H{sub 2} plasmas, reactions of radicals that diffuse into the SiOCH and photons that penetrate into the SiOCH can remove -CH{sub 3} groups. Due to its higher reactivity, cleaning with Ar/O{sub 2} plasmas removes more -CH{sub 3} groups than He/H{sub 2} plasmas, and so produce more free radical sites, such as -SiO{sub 2} Bullet (a -SiO{sub 2}-CH{sub 3} site with the -CH{sub 3} group removed).Upon exposure to humid air, these free radical sites can chemisorb H{sub 2}O to form hydrophilic Si-OH which can further physisorb H{sub 2}O through hydrogen bonding to form Si-OH(H{sub 2}O). With the high dielectric constant of water, even a small percentage of water uptake can significantly increase the effective dielectric constant of SiOCH. In this paper, we report on results from a computational investigation of the cleaning of SiOCH using Ar/O{sub 2} or He/H{sub 2} plasmas and subsequent exposure to humid air. The authors found that plasma cleaning with He/H{sub 2} mixtures produce less demethylation than cleaning with Ar/O{sub 2} plasmas, as so results in less water uptake, and a smaller increase in dielectric constant. The water that produces the increase in dielectric constant is roughly half chemisorbed and half physisorbed, the latter of which can be removed with mild heating. Sealing the pores with NH{sub 3} plasma treatment reduces water uptake and helps prevent the increase in dielectric constant.

  7. Disruption of the OCH1 and MNN1 genes decrease N-glycosylation on glycoprotein expressed in Kluyveromyces lactis.

    PubMed

    Liu, Bo; Gong, Xin; Chang, Shaohong; Yang, Yili; Song, Miao; Duan, Demin; Wang, Lina; Ma, Qingjun; Wu, Jun

    2009-08-20

    Glycoproteins secreted by the yeast Kluyveromyces lactis are usually modified by the addition at asparagines-linked glycosylation sites of heterogeneous mannan residues. The secreted glycoproteins in K. lactis that become hypermannosylated will bear a non-human glycosylation pattern and can adversely affect the half-life, tissue distribution and immunogenicity of a therapeutic protein. Here, we describe engineering a K. lactis strain to produce non-hypermannosylated glycoprotein, decreasing the outer-chain mannose residues of N-linked oligosaccharides. We investigated and developed the method of two-step homologous recombination to knockout the OCH1 gene, encoding alpha1,6-mannosyltransferase and MNN1 gene, which is homologue of Saccharomyces cerevisiae MNN1, encoding a putative alpha1,3-mannosyltransferase. We found the Kloch1 mutant strain has a defect in hyperglycosylation, inability in adding mannose to the core oligosaccharide. The N-linked oligosaccharides assembled on a secretory glycoprotein, HSA/GM-CSF in Kloch1 mutant, contained oligosaccharide Man(13-14)GlcNAc(2), and in Kloch1 mnn1 mutant, contained oligosaccharide Man(9-11)GlcNAc(2), whereas those in the wild-type strain, consisted of oligosaccharides with heterogeneous sizes, Man(>30)GlcNAc(2). Taken together, these results indicated that KlOch1p plays a key role in the outer-chain mannosylation of N-linked oligosaccharides in K. lactis. The KlMnn1p, was proved to be certain contribution to the outer hypermannosylation, most possibly encodes alpha1,3-mannosyltransferase. Therefore, the Kloch1 and Kloch1 mnn1 mutants can be used as a foundational host to produce glycoproteins lacking the outer-chain hypermannoses and further maybe applicable to be a promising system for yeast therapeutic protein production.

  8. A Study of Structural Changes in Pressed Semiproducts from Aluminum Alloy V95ochT2 in the Range of Dark Spots

    NASA Astrophysics Data System (ADS)

    Shigapov, A. I.; Il'inkova, T. A.; Kuryntsev, S. V.; Petrova, E. P.

    2017-01-01

    Seven heats of alloy V95ochT2 are studied after a heat treatment imitating the conditions of the appearance of dark spots in the production process and anodic oxidizing (anodizing). The mechanical properties, the hardness, the structure, and the electrical conductivity of the alloy are determined. The causes and conditions of the appearance of dark spots are analyzed. The transparence of the film is shown to worsen upon formation of particles of second phase in the alloy.

  9. Design of peptides with alpha,beta-dehydro residues: pseudo-tripeptide N-benzyloxycarbonyl-DeltaLeu-L-Ala-L-Leu-OCH3.

    PubMed

    Makker, Jyoti; Dey, Sharmistha; Kumar, Pravindra; Singh, Tej P

    2002-04-01

    The title peptide N-benzyloxycarbonyl-DeltaLeu-L-Ala-L-Leu-OCH(3) [methyl N-(benzyloxycarbonyl)-alpha,beta-dehydroleucyl-L-alanyl-L-leucinate], C(24)H(35)N(3)O(6), was synthesized in the solution phase. The peptide adopts a type II' beta-turn conformation which is stabilized by an intramolecular 4 --> 1 N-H* * *O hydrogen bond. The crystal packing is stabilized by two intermolecular N-H* * *O hydrogen bonds.

  10. Conformational and spectroscopic study of xanthogen ethyl formates, ROC(S)SC(O)OCH2CH3. Isolation of CH3CH2OC(O)SH

    NASA Astrophysics Data System (ADS)

    Juncal, Luciana C.; Cozzarín, Melina V.; Romano, Rosana M.

    2015-03-01

    ROC(S)SC(O)OCH2CH3, with R = CH3sbnd , (CH3)2CHsbnd and CH3(CH2)2sbnd , were obtained through the reaction between potassium xanthate salts, ROC(S)SK, and ethyl chloroformate, ClC(O)OCH2CH3. The liquid compounds were identified and characterized by 1H and 13C NMR and mass spectrometry. The conformations adopted by the molecules were studied by DFT methods. 6 conformers were theoretically predicted for R = CH3sbnd and (CH3)2CHsbnd , while the conformational flexibility of the n-propyl substituent increases the total number of feasible rotamers to 21. For the three molecules, the conformers can be associated in 3 groups, being the most stable the AS forms - the Cdbnd S double bond anti (A) with respect to the Csbnd S single bond and the Ssbnd C single bond syn (S) with respect to the Cdbnd O double bond - followed by AA and SS conformers. The vibrational spectra were interpreted in terms of the predicted conformational equilibrium, presenting the ν(Cdbnd O) spectral region signals corresponding to the three groups of conformers. A moderated pre-resonance Raman enhancement of the ν(Cdbnd S) vibrational mode of CH3(CH2)2OC(S)SC(O)OCH2CH3 was detected, when the excitation radiation approaches the energy of a n → π∗ electronic transition associated with the Cdbnd S chromophore. UV-visible spectra in different solvents were measured and interpreted in terms of TD-DFT calculations. The unknown molecule CH3CH2OC(O)SH was isolated by the UV-visible photolysis of CH3OC(S)SC(O)OCH2CH3 isolated in Ar matrix, and also obtained as a side-product of the reaction between potassium xanthate salts, ROC(S)SK, and ethyl chloroformate, ClC(O)OCH2CH3.

  11. Disproportionation and thermochemical sulfate reduction reactions in S-H20-Ch4 and S-D2O-CH4 systems from 200 to 340 °C at elevated pressures

    USGS Publications Warehouse

    Yuan, Shunda; Chou, I-Ming; Burruss, Robert A.

    2013-01-01

    Elemental sulfur, as a transient intermediate compound, by-product, or catalyst, plays significant roles in thermochemical sulfate reduction (TSR) reactions. However, the mechanisms of the reactions in S-H2O-hydrocarbons systems are not clear. To improve our understanding of reaction mechanisms, we conducted a series of experiments between 200 and 340 °C for S-H2O-CH4, S-D2O-CH4, and S-CH4-1m ZnBr2 systems in fused silica capillary capsules (FSCC). After a heating period ranging from 24 to 2160 hours (hrs), the quenched samples were analyzed by Raman spectroscopy. Combined with the in situ Raman spectra collected at high temperatures and pressures in the S-H2O and S-H2O-CH4 systems, our results showed that (1) the disproportionation of sulfur in the S-H2O-CH4 system occurred at temperatures above 200 °C and produced H2S, SO42-, and possibly trace amount of HSO4-; (2) sulfate (and bisulfate), in the presence of sulfur, can be reduced by methane between 250 and 340 °C to produce CO2 and H2S, and these TSR temperatures are much closer to those of the natural system (2O-CH4 system may take place simultaneously, with TSR being favored at higher temperatures; and (4) in the system S-D2O-CH4, both TSR and the competitive disproportionation reactions occurred simultaneously at temperatures above 300 °C, but these reactions were very slow at lower temperatures. Our observation of methane reaction at 250 °C in a laboratory time scale suggests that, in a geologic time scale, methane may be destroyed by TSR reactions at temperatures > 200 °C that can be reached by deep drilling for hydrocarbon resources.

  12. A computational study of the addition of ReO3L (L = Cl(-), CH3, OCH3 and Cp) to ethenone.

    PubMed

    Aniagyei, Albert; Tia, Richard; Adei, Evans

    2016-01-01

    The periselectivity and chemoselectivity of the addition of transition metal oxides of the type ReO3L (L = Cl, CH3, OCH3 and Cp) to ethenone have been explored at the MO6 and B3LYP/LACVP* levels of theory. The activation barriers and reaction energies for the stepwise and concerted addition pathways involving multiple spin states have been computed. In the reaction of ReO3L (L = Cl(-), OCH3, CH3 and Cp) with ethenone, the concerted [2 + 2] addition of the metal oxide across the C=C and C=O double bond to form either metalla-2-oxetane-3-one or metalla-2,4-dioxolane is the most kinetically favored over the formation of metalla-2,5-dioxolane-3-one from the direct [3 + 2] addition pathway. The trends in activation and reaction energies for the formation of metalla-2-oxetane-3-one and metalla-2,4-dioxolane are Cp < Cl(-) < OCH3 < CH3 and Cp < OCH3 < CH3 < Cl(-) and for the reaction energies are Cp < OCH3 < Cl(-) < CH3 and Cp < CH3 < OCH3 < Cl CH3. The concerted [3 + 2] addition of the metal oxide across the C=C double of the ethenone to form species metalla-2,5-dioxolane-3-one is thermodynamically the most favored for the ligand L = Cp. The direct [2 + 2] addition pathways leading to the formations of metalla-2-oxetane-3-one and metalla-2,4-dioxolane is thermodynamically the most favored for the ligands L = OCH3 and Cl(-). The difference between the calculated [2 + 2] activation barriers for the addition of the metal oxide LReO3 across the C=C and C=O functionalities of ethenone are small except for the case of L = Cl(-) and OCH3. The rearrangement of the metalla-2-oxetane-3-one-metalla-2,5-dioxolane-3-one even though feasible, are unfavorable due to high activation energies of their rate-determining steps. For the rearrangement of the metalla-2-oxetane-3-one to metalla-2,5-dioxolane-3-one, the trends in activation barriers is found to follow the order OCH3 < Cl(-) < CH3 < Cp. The trends in the activation energies for

  13. Investigation of the O+allyl addition/elimination reaction pathways from the OCH{sub 2}CHCH{sub 2} radical intermediate

    SciTech Connect

    FitzPatrick, Benjamin L.; Lau, K.-C.; Butler, Laurie J.; Lee, S.-H.; Lin, Jim Jr-Min

    2008-08-28

    These experiments study the preparation of and product channels resulting from OCH{sub 2}CHCH{sub 2}, a key radical intermediate in the O+allyl bimolecular reaction. The data include velocity map imaging and molecular beam scattering results to probe the photolytic generation of the radical intermediate and the subsequent pathways by which the radicals access the energetically allowed product channels of the bimolecular reaction. The photodissociation of epichlorohydrin at 193.3 nm produces chlorine atoms and c-OCH{sub 2}CHCH{sub 2} radicals; these undergo a facile ring opening to the OCH{sub 2}CHCH{sub 2} radical intermediate. State-selective resonance-enhanced multiphoton ionization (REMPI) detection resolves the velocity distributions of ground and spin-orbit excited state chlorine independently, allowing for a more accurate determination of the internal energy distribution of the nascent radicals. We obtain good agreement detecting the velocity distributions of the Cl atoms with REMPI, vacuum ultraviolet (VUV) photoionization at 13.8 eV, and electron bombardment ionization; all show a bimodal distribution of recoil kinetic energies. The dominant high recoil kinetic energy feature peaks near 33 kcal/mol. To elucidate the product channels resulting from the OCH{sub 2}CHCH{sub 2} radical intermediate, the crossed laser-molecular beam experiment uses VUV photoionization and detects the velocity distribution of the possible products. The data identify the three dominant product channels as C{sub 3}H{sub 4}O (acrolein)+H, C{sub 2}H{sub 4}+HCO (formyl radical), and H{sub 2}CO (formaldehyde)+C{sub 2}H{sub 3}. A small signal from C{sub 2}H{sub 2}O (ketene) product is also detected. The measured velocity distributions and relative signal intensities at m/e=27, 28, and 29 at two photoionization energies show that the most exothermic product channel, C{sub 2}H{sub 5}+CO, does not contribute significantly to the product branching. The higher internal energy onset of the

  14. Theoretical investigation on the atmospheric fate of CF3C(O)OCH 2O radical: alpha-ester rearrangement vs oxidation at 298 K.

    PubMed

    Mishra, Bhupesh Kumar

    2014-09-01

    A theoretical study on the mechanism of the thermal decomposition of CF(3)C(O)OCH(2)O radical is presented for the first time. Geometry optimization and frequency calculations were performed at the MPWB1K/6-31 + G(d, p) level of theory and energetic information further refined by calculating the energy of the species using G2(MP2) theory. Three plausible decomposition pathways including α-ester rearrangement, reaction with O(2) and thermal decomposition (C-O bond scission) were considered in detail. Our results reveal that reaction with O(2) is the dominant path for the decomposition of CF(3)C(O)OCH(2)O radical in the atmosphere, involving the lowest energy barrier, which is in accord with experimental findings. Our theoretical results also suggest that α-ester rearrangement leading to the formation of trifluoroacetic acid TFA makes a negligible contribution to decomposition of the title alkoxy radical. The thermal rate constants for the above decomposition pathways were evaluated using canonical transition state theory (CTST) at 298 K.

  15. The remarkable dissociation chemistry of 2-aminoxyethanol ions NH2OCH2CH2OH+studied by experiment and theory

    NASA Astrophysics Data System (ADS)

    Jobst, Karl J.; Ruttink, Paul J. A.; Terlouw, Johan K.

    2008-02-01

    Low-energy 2-aminoxyethanol molecular ions NH2OCH2CH2OH+ exhibit a surprisingly rich gas-phase ion chemistry. They spontaneously undergo five major dissociations in the microsecond timeframe, yielding ions of m/z 61, 60, 46, 32 and 18. Our tandem mass spectrometry experiments indicate that these reactions correspond to the generation of HOCH2CH(OH)+ (protonated glycolaldehyde), HOCH2C(O)H+ (ionized glycolaldehyde), HC(OH)NH2+ (protonated formamide), CH2OH2+ (the methylene oxonium ion) and NH4+. A mechanistic analysis of these processes using the CBS-QB3 model chemistry shows that the molecular ions undergo a 1,4-H shift followed by a facile isomerization into the ion-molecule complex [HOCH2C(O)H+]...[NH3] which acts as the reacting configuration for the five exothermic dissociation processes. Analysis of the D-labelled isotopomer ND2OCH2CH2OD+, in conjunction with our computational results, shows that proton-transport catalysis may be responsible for the partial conversion of the m/z 60 glycolaldehyde ions into the more stable 1,2-dihydroxyethene isomer HOC(H)C(H)OH+.

  16. Isoelectronic caesium compounds: the triphosphenide Cs[tBu3SiPPPSitBu3] and the enolate Cs[OCH=CH2].

    PubMed

    Lerner, Hans-Wolfram; Sänger, Inge; Schödel, Frauke; Lorbach, Andreas; Bolte, Michael; Wagner, Matthias

    2008-02-14

    The caesium triphosphenide Cs[tBu3SiPPPSitBu3] was accessible from the reaction of CsF with the sodium triphosphenide Na[tBu3SiPPPSitBu3] in tetrahydrofuran at room temperature. In contrast to the preparation of tetrahydrofuran-solvated silanides M[SitBu3] (M = Li, Na, K), our efforts to synthesize the caesium silanide Cs[SitBu3] as a tetrahydrofuran complex failed. When tBu3SiBr was treated with an excess of caesium metal in tetrahydrofuran at room temperature, the caesium enolate Cs[OCH=CH2] and the supersilane tBu3SiH formed rather than the silanide Cs[SitBu3]. X-Ray quality crystals of the enolate Cs[OCH=CH2] (orthorhombic, Pnma) were obtained from tetrahydrofuran at ambient temperature. In contrast to the structures of its homologues M[tBu3SiPPPSitBu3] (M = Na, K), the caesium triphosphenide Cs[tBu3SiPPPSitBu3] features a polymer in the solid state (orthorhombic, Cmcm).

  17. Atmospheric chemistry of C4F9OC2H5 (HFE-7200), C4F9OCH3 (HFE-7100), C3F7OCH3 (HFE-7000) and C3F7CH2OH: temperature dependence of the kinetics of their reactions with OH radicals, atmospheric lifetimes and global warming potentials.

    PubMed

    Bravo, Iván; Díaz-de-Mera, Yolanda; Aranda, Alfonso; Smith, Kevin; Shine, Keith P; Marston, George

    2010-05-21

    The atmospheric chemistry of several gases used in industrial applications, C(4)F(9)OC(2)H(5) (HFE-7200), C(4)F(9)OCH(3) (HFE-7100), C(3)F(7)OCH(3) (HFE-7000) and C(3)F(7)CH(2)OH, has been studied. The discharge flow technique coupled with mass-spectrometric detection has been used to study the kinetics of their reactions with OH radicals as a function of temperature. The infrared spectra of the compounds have also been measured. The following Arrhenius expressions for the reactions were determined (in units of cm(3) molecule(-1) s(-1)): k(OH + HFE-7200) = (6.9(-1.7)(+2.3)) x 10(-11) exp(-(2030 +/- 190)/T); k(OH + HFE-7100) = (2.8(-1.5)(+3.2)) x 10(-11) exp(-(2200 +/- 490)/T); k(OH + HFE-7000) = (2.0(-0.7)(+1.2)) x 10(-11) exp(-(2130 +/- 290)/T); and k(OH + C(3)F(7)CH(2)OH) = (1.4(-0.2)(+0.3)) x 10(-11) exp(-(1460 +/- 120)/T). From the infrared spectra, radiative forcing efficiencies were determined and compared with earlier estimates in the literature. These were combined with the kinetic data to estimate 100-year time horizon global warming potentials relative to CO(2) of 69, 337, 499 and 36 for HFE-7200, HFE-7100, HFE-7000 and CF(3)CF(2)CF(2)CH(2)OH, respectively.

  18. Forskolebarn och TV.

    ERIC Educational Resources Information Center

    Sonesson, Inga

    This analysis of the relationship between mothers' attitudes toward TV and children's viewing habits, and the relationships between this behavior and the personal and/or social problems of the child, is based on data gathered in interviews with 250 preschool children, their mothers, and their teachers. Findings indicate a positive correlation…

  19. Evaluation of a novel approach for peptide sequencing: laser-induced acoustic desorption combined with P(OCH(3))(2)(+) chemical ionization and collision-activated dissociation in a Fourier transform ion cyclotron resonance mass spectrometer.

    PubMed

    Somuramasami, Jayalakshmi; Kenttämaa, Hilkka I

    2007-03-01

    A novel mass spectrometric method has been developed for obtaining sequence information on small peptides. The peptides are desorbed as intact neutral molecules into a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR) by means of laser-induced acoustic desorption (LIAD). Reactions of the neutral peptides with the dimethoxyphosphenium ion, P(OCH(3))(2)(+), occur predominantly by addition of the peptide to P(OCH(3))(2)(+) followed by the loss of two methanol molecules, thus yielding product ions with the composition (peptide + P - 2H)(+). Upon sustained off-resonance irradiation for collision-activated dissociation (SORI-CAD), the (peptide + P - 2H)(+) ions undergo successive losses of CO and NHCHR or H(2)O, CO, and NHCHR to yield sequence-related fragment ions in addition to the regular a(n)- and b(n)-type ions. Under the same conditions, SORI-CAD of the analogous protonated peptides predominantly yields the regular a(n)- and b(n)-type ions. The mechanisms of the reactions of peptides with P(OCH(3))(2)(+) and the dissociation of the (peptide + P - 2H)(+) ions were examined by using model peptides and molecular orbital calculations.

  20. Evaluation of a Novel Approach for Peptide Sequencing: Laser-induced Acoustic Desorption Combined with P(OCH3)2+ Chemical Ionization and Collision-activated Dissociation in a Fourier Transform Ion Cyclotron Resonance Mass Spectrometer

    PubMed Central

    Somuramasami, Jayalakshmi; Kenttämaa, Hilkka I.

    2007-01-01

    A novel mass spectrometric method has been developed for obtaining sequence information on small peptides. The peptides are desorbed as intact neutral molecules into a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR) by means of laser-induced acoustic desorption (LIAD). Reactions of the neutral peptides with the dimethoxyphosphenium ion, P(OCH3)2+, occur predominantly by addition of the peptide to P(OCH3)2+ followed by the loss of two methanol molecules, thus yielding product ions with the composition (peptide + P − 2H)+. Upon sustained off-resonance irradiation for collision-activated dissociation (SORI-CAD), the (peptide + P − 2H)+ ions undergo successive losses of CO and NH = CHR or H2O, CO, and NH = CHR to yield sequence-related fragment ions in addition to the regular an- and bn-type ions. Under the same conditions, SORI-CAD of the analogous protonated peptides predominantly yields the regular an- and bn-type ions. The mechanisms of the reactions of peptides with P(OCH3)2+ and the dissociation of the (peptide + P − 2H)+ ions were examined by using model peptides and molecular orbital calculations. PMID:17157527

  1. Investigating the H2-He-H2O-CH4 equation of state in the deep troposphere of Jupiter

    NASA Astrophysics Data System (ADS)

    Karpowicz, Bryan M.; Steffes, Paul G.

    2013-03-01

    In this work, a new equation of state for a H2-He-H2O-CH4 mixture is presented. The equation is optimized for the deep jovian atmosphere (∼100 bars) where the NASA Juno Microwave Radiometer (MWR) will probe. The methodology used is based upon that of Lemmon and Jacobsen (Lemmon, E.W., Jacobsen, R.T. [2004]. J. Phys. Chem. Ref. Data 33, 593-+) and Kunz et al. (Kunz, O., Klimeck, R., Wagner, W., Jaeschke, M. [2006]. Technical Monograph, VDI-Verlag). This methodology is used in combination with available published thermodynamic measurements and with new pressure-Volume-Temperature (pVT) measurements of H2-H2O mixtures conducted with the jovian simulator described in Karpowicz and Steffes (Karpowicz, B.M., Steffes, P.G. [2011]. Icarus 212, 210-223). In addition to being necessary to interpret laboratory measurements, the new equation of state is important in developing temperature pressure profiles of the deep jovian atmosphere. This is demonstrated by incorporating the new equation of state into an updated version of the DeBoer (DeBoer, D.R. [1995]. Ph.D. Thesis, Georgia Institute of Technology) Thermo-Chemical Model (TCM), and viewing its effect on the resulting simulated jovian atmospheric profiles.

  2. Global Uncertainty Propagation and Sensitivity Analysis in the CH3OCH2 + O2 System: Combining Experiment and Theory To Constrain Key Rate Coefficients in DME Combustion.

    PubMed

    Shannon, R J; Tomlin, A S; Robertson, S H; Blitz, M A; Pilling, M J; Seakins, P W

    2015-07-16

    Statistical rate theory calculations, in particular formulations of the chemical master equation, are widely used to calculate rate coefficients of interest in combustion environments as a function of temperature and pressure. However, despite the increasing accuracy of electronic structure calculations, small uncertainties in the input parameters for these master equation models can lead to relatively large uncertainties in the calculated rate coefficients. Master equation input parameters may be constrained further by using experimental data and the relationship between experiment and theory warrants further investigation. In this work, the CH3OCH2 + O2 system, of relevance to the combustion of dimethyl ether (DME), is used as an example and the input parameters for master equation calculations on this system are refined through fitting to experimental data. Complementing these fitting calculations, global sensitivity analysis is used to explore which input parameters are constrained by which experimental conditions, and which parameters need to be further constrained to accurately predict key elementary rate coefficients. Finally, uncertainties in the calculated rate coefficients are obtained using both correlated and uncorrelated distributions of input parameters.

  3. Communication: Direct observation of a hydrophobic bond in loop closure of a capped (-OCH2CH2-)n oligomer in water

    NASA Astrophysics Data System (ADS)

    Chaudhari, Mangesh I.; Pratt, Lawrence R.; Paulaitis, Michael E.

    2010-12-01

    The small r variation of the probability density P(r) for end-to-end separations of a -CH _2CH _3 capped (-OCH _2CH _2-) _n oligomer in water is computed to be closely similar to the CH _4\\cdots CH _4 potential of mean force under the same circumstances. Since the aqueous solution CH _4\\cdots CH _4 potential of mean force is the natural physical definition of a primitive hydrophobic bond, the present result identifies an experimentally accessible circumstance for direct observation of a hydrophobic bond which has not been observed previously because of the low solubility of CH _4 in water. The physical picture is that the soluble chain molecules carry the capping groups into aqueous solution, and permits them to find one another with reasonable frequency. Comparison with the corresponding results without the solvent shows that hydration of the solute oxygen atoms swells the chain molecule globule. This supports the view that the chain molecule globule might have a secondary effect on the hydrophobic interaction that is of first interest here. The volume of the chain molecule globule is important for comparing the probabilities with and without solvent because it characterizes the local concentration of capping groups. Study of other capping groups to enable x-ray and neutron diffraction measurements of P(r) is discussed.

  4. Oxovanadium alkoxides: Structure, reactivity, and sup 51 V NMR characteristics. Crystal and molecular structures of VO(OCH sub 2 CH sub 2 Cl) sub 3 and VOCl sub 2 (THF) sub 2 H sub 2 O

    SciTech Connect

    Priebsch, W.; Rehder, D. )

    1990-08-08

    The vanadyl esters VO(OR){sub 3} (R = Me, Et, Pr, iPr, sBu, tBu, CH{sub 2}CH{sub 2}F, CH{sub 2}CH{sub 2}Cl, CH{sub 2}CCl{sub 3}) have been prepared and their association properties in pentane investigated by {sup 51}V NMR. Limiting (low concentration) {delta}({sup 51}V) values depend on the bulk of R (highest {sup 51}V shielding for tBu). Shielding decreases with increasing concentration (more pronounced for small R groups), owing to the formation of oligomers, probably connected by {mu}-OR groups. The X-ray diffraction study of VO(OCH{sub 2}CH{sub 2}Cl){sub 3} reveals dimer association of molecules belonging to adjacent unit cells via long V-OR bonds (226.1 (2) pm), and a trigonal-bipyramidal geometry for each monomeric unit. From the reaction between VOCl{sub 3} and diols (glycol, 1,3-propanediol, 1,2-, 2,3-, 1,3-, and 1,4-butanediol), complexes are obtained that contain the {l brace}VOCl(OR){sub 2}{r brace} and {l brace}VOCl{sub 2}OR{r brace} moieties and the alcohol coordinated in the monofunctional or bifunctional (chelating and bridging) mode. The {sup 51}V NMR spectrum of VOCl{sub 2}OCH(Me)CH(Me)OH exhibits resolved {sup 51}V-{sup 35,37}Cl coupling: J({sup 51}V-{sup 35}Cl) = 100 Hz; J({sup 51}V-{sup 37}Cl) = 83 Hz. V{sup V}OCl{sub 2}(OCH{sub 2}CH{sub 2}CH{sub 2}OH) reacts with 1,4-butanediol to form V{sup IV}OCl{sub 2}(THF){sub 2}(OH{sub 2}). In the presence of COCL{sub 3}, THF undergoes ether splitting, chlorination, and coordination to vanadium to yield VOCl{sub 2}(OCH{sub 2}CH{sub 2}CH{sub 2}CH{sub 2}Cl). 35 refs., 7 figs., 7 tabs.

  5. Correlation between stress-induced leakage current and dielectric degradation in ultra-porous SiOCH low-k materials

    SciTech Connect

    Wu, C. De Wolf, I.; Li, Y.; Leśniewska, A.; Varela Pedreira, O.; Marneffe, J.-F. de; Ciofi, I.; Verdonck, P.; Baklanov, M. R.; Bömmels, J.; Tőkei, Zs.; Croes, K.

    2015-10-28

    Stress-Induced Leakage Current (SILC) behavior during the dielectric degradation of ultra-porous SiOCH low-k materials was investigated. Under high voltage stress, SILC increases to a critical value before final hard breakdown. This SILC increase rate is mainly driven by the injected charges and is negligibly influenced by temperature and voltage. SILC is found to be transient and shows a t{sup −1} relaxation behavior, where t is the storage time at low voltages. This t{sup −1} transient behavior, described by the tunneling front model, is caused by both electron charging of neutral defects in the dielectric close to the cathode interface and discharging of donor defects close to the anode interface. These defects have a uniform density distribution within the probed depth range, which is confirmed by the observed flat band voltage shift results collected during the low voltage storage. By applying an additional discharging step after the low voltage storage, the trap energies and spatial distributions are derived. In a highly degraded low-k dielectric, the majority of defects have a trap depth between 3.4 eV and 3.6 eV and a density level of 1 × 10{sup 18 }eV{sup −1 }cm{sup −3}. The relation between the defect density N and the total amount of the injected charges Q is measured to be sub-linear, N ∼ Q{sup 0.45±0.07}. The physical nature of these stress-induced defects is suggested to be caused by the degradation of the Si-O based skeleton in the low-k dielectric.

  6. The Golgi α-1,6 mannosyltransferase KlOch1p of Kluyveromyces lactis is required for Ca2+/calmodulin-based signaling and for proper mitochondrial functionality

    PubMed Central

    2009-01-01

    Background Protein N-glycosylation is a relevant metabolic pathway in eukaryotes and plays key roles in cell processes. In yeasts, outer chain branching is initiated in the Golgi apparatus by the alpha-1,6-mannosyltransferase Och1p. Results Here we report that, in Kluyveromyces lactis, this glycosyltransferase is also required to maintain functional mitochondria and calcium homeostasis. Cells carrying a mutation in KlOCH1 gene showed altered mitochondrial morphology, increased accumulation of ROS and reduced expression of calcium signalling genes such as calmodulin and calcineurin. Intracellular calcium concentration was also reduced in the mutant cells with respect to the wild type counterparts. Phenotypes that occur in cells lacking the alpha-1,6-mannosyltransferase, including oxidative stress and impaired mitochondria functionality, were suppressed by increased dosage of KlCmd1p. This, in turn, acts through the action of calcineurin. Conclusions Proper functioning of the alpha-1,6-mannosyltransferase in the N-glycosylation pathway of K. lactis is required for maintaining normal calcium homeostasis; this is necessary for physiological mitochondria dynamics and functionality. PMID:20003441

  7. Fluid evolution in the H 2O-CH 4-CO 2-NaCl system during emerald mineralization at Gravelotte, Murchison Greenstone Belt, Northeast Transvaal, South Africa

    NASA Astrophysics Data System (ADS)

    Nwe, Yin Yin; Morteani, Giulio

    1993-01-01

    Fluid evolution during emerald mineralization at the Gravelotte emerald mine has been studied by microthermometry and laser Raman microprobe spectrometry. The emeralds and associated phenakites occur on the flanks of a highly metasomatised albitite pegmatoid body and in the biotite schists at and near its contact. The fluids lie in the H 2O-CH 4-CO 2-NaCl system and four types of inclusions are characterised based on time of trapping and fluid contents. The earliest type 1 inclusions, found in phenakites and the emeralds which formed from them, are low salinity (<6 wt% NaCl) with up to 18 mol% CH 4. The carbonic phase contains over 93 mol% CH 4 and variable small amounts of CO 2, C 2H 6, N 2, and H 2S. The solvus crest for this system lies at ≈400°C, closer to the H 2O end of the join. With time the fluids become less CH 4 rich and more saline. The type 2 fluids are highly variable in both CH 4-CO 2 contents and salinity, reflecting mixing of type 1 fluids with higher salinity brines. The late type 3 and 4 inclusions are CH 4-CO 2-free high salinity inclusions with up to 38 wt% NaCl. Trapping conditions for the type 1 fluids were around 450-500°C and 4 kb based on model isochores and geologic evidence. During the trapping of type 2 inclusions, fluid pressures probably fluctuated due to opening and resealing of fractures. Approximate P- T ranges of trapping for these and other later inclusions have been defined, minimum trapping temperatures for types 2, 3, and 4 being, respectively, 250, 150, and 240°C, and pressures in the range of 1-4 kb. Calculations of ƒ O 2 show an initial low ƒ O 2 between QFM and the synthetic graphite-CH 4 buffer for the type 1 fluids. This rises to above QFM in the later stages. Such low initial values are uncharacteristic of granitic pegmatite systems, and it is suggested that the phenakites formed in the post-magmatic stage of alkali metasomatism when the albitization took place. In the later stages, phenakite was converted to

  8. Synthesis, structure and reactivity of rare-earth metallacarborane alkyls [η(1):η(5)-O(CH2)2C2B9H9]Ln(σ:η(1)-CH2C6H4-o-NMe2)(THF)2.

    PubMed

    Yang, Jingying; Xie, Zuowei

    2015-04-14

    Rare-earth metallacarborane alkyls can be stabilized by the incorporation of a functional sidearm into both π and σ ligands. Reaction of [Me3NH][7,8-O(CH2)2-7,8-C2B9H10] with one equiv. of Ln(CH2C6H4-o-NMe2)3 gave metallacarborane alkyls [η(1):η(5)-O(CH2)2C2B9H9]Ln(σ:η(1)-CH2C6H4-o-NMe2)(THF)2 (Ln = Y (), Gd (), Er ()) via alkane elimination. They represent the first examples of rare-earth metallacarborane alkyls. Treatment of with RN[double bond, length as m-dash]C[double bond, length as m-dash]NR (R = Cy, (i)Pr) or 2-benzoylpyridine afforded the corresponding mono-insertion products [η(1):η(5)-O(CH2)2C2B9H9]Y[η(2)-(RN)2C(CH2C6H4-o-NMe2)](DME) (R = Cy (), (i)Pr ()) or [η(1):η(5)-O(CH2)2C2B9H9]Y[C5H4NC(Ph)(CH2C6H4-o-NMe2)O](THF)2 (), respectively. Complex also reacted with ArNCO or ArNC (Ar = 2,6-diisopropylphenyl, 2,6-dimethylphenyl) to give di-insertion products [η(1):η(5)-O(CH2)2C2B9H9]Y[OC([double bond, length as m-dash]NC6H3Me2)N(C6H3Me2)C(CH2C6H4-o-NMe2)O](THF)2 () or [η(1):η(5)-O(CH2)2C2B9H9]Y[C([double bond, length as m-dash]NC6H3(i)Pr2)C([double bond, length as m-dash]NC6H3(i)Pr2)(CH2C6H4-o-NMe2)](DME) (). These results showed that the reactivity pattern of the Ln-C σ bond in rare-earth metallacarborane alkyls was dependent on the nature of the unsaturated organic molecules. New complexes were characterized by various spectroscopic techniques and elemental analysis. Some were further confirmed by single-crystal X-ray analysis.

  9. Transfer of Amide and 2-Methoxyethoxy Groups and Sodium Encapsulation in the Reaction of TaCl3[N(TMS)2]2 with Sodium Bis(2-methoxyethoxy)aluminum Hydride: X-ray Structure of [NaAl{N(TMS)2}(OCH2CH2OMe)3]2

    SciTech Connect

    Huang, Shih-Huang Huang; Wang, Xiaoping; Richmond, Michael G.

    2009-01-01

    The reaction between the tantalum compound TaCl3[N(TMS)2]2 and the hydridic reducing agent sodium bis(2-methoxyethoxy)aluminum hydride (Vitride) has been investigated in toluene solution at room temperature and found to afford the dimeric aluminate complex [NaAl{N(TMS)2}(OCH2CH2OMe)3]2 as the sole isolable product. The molecular structure of the product establishes the existence of a four-coordinate aluminum atom and the formal transfer of the 2-methoxyethoxy and bis(trimethylsilyl)amide groups to the aluminate product. The aggregation of two NaAl{N(TMS)2}(OCH2CH2OMe)3 units serves to bind the two sodium cations in a crown-ether fashion through six ancillary oxygen atoms.

  10. VAPOR PRESSURES, LIQUID MOLAR VOLUMES, VAPOR NON- IDEALITIES, AND CRITICAL PROPERTIES OF SOME FLUORINATED ETHERS: CF3OCF2OCF3, CF3OCF2 CF2H, c-CF2CF2CF2O, CF3OCF2H, AND CF3OCH3; AND OF CCl3F AND CF2ClH

    EPA Science Inventory

    Vapor pressures, compressibilities, expansivities, and molar volumes of the liquid phase have been measured between room temperature and the critical temperature for a series of fluorinated ethers: CF3OCF2OCF3, CF3OCF2CF2H, c-CF2CF2CF2O, CF3OCF2H, and CF3OCH3. Vapor-phase non-ide...

  11. Synthesis and characterization of a new monophosphate (5-Cl-2,4-(OCH{sub 3}){sub 2}C{sub 6}H{sub 2}NH{sub 3})H{sub 2}PO{sub 4}

    SciTech Connect

    Kefi, R.; Abid, S.; Nasr, C. Ben . E-mail: cherif.bennasr@fsb.rnu.tn; Rzaigui, M.

    2007-03-22

    Chemical preparation, crystal structure and NMR spectroscopy of a new organic cation 5-chloro(2,4-dimethoxy)anilinium monophosphate H{sub 2}PO{sub 4} are given. This new compound crystallizes in the monoclinic system, with the space group P2{sub 1}/c and the following parameters: a=5.524(2)A, b=9.303(2)A, c=23.388(2)A, {beta}=90.66(4), V=1201.8(2)A{sup 3}, Z=4 and D{sub x}=1.573gcm{sup -3}. Crystal structure has been determined and refined to R=0.031 and R{sub w}=0.080 using 1702 independent reflections. Structure can be described as an infinite (H{sub 2}PO{sub 4}){sub n}{sup n-} corrugated chains in the a-direction. The organic groups (5-Cl-2,4-(OCH{sub 3}){sub 2}C{sub 6}H{sub 2}NH{sub 3}){sup +} are anchored between adjacent polyanions through multiple hydrogen bonds. This compound is also investigated by IR, thermal, and solid-state, {sup 13}C, {sup 31}P MAS NMR spectroscopies.

  12. [Ni(OH)3W6O18(OCH2)3CCH2OH]4–: the first tris-functionalized Anderson-type heteropolytungstate† †Electronic supplementary information (ESI) available: Experimental procedures, synthesis details, characterization data, including IR, ESI-MS, TGA, elemental analysis and X-ray crystallography with CIF file. CCDC 1477611. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c6cc04326g Click here for additional data file. Click here for additional data file.

    PubMed Central

    Gumerova, Nadiia I.; Roller, Alexander

    2016-01-01

    Na2[TMA]2[Ni(OH)3W6O18(OCH2)3CCH2OH]·9H2O represents the first covalent tris-functionalized Anderson-type heteropolytungstate and was characterized by single-crystal X-ray diffraction, electrospray ionization mass spectrometry, TGA and IR spectroscopy. Zeta potential measurements in solutions containing human serum albumin were performed to investigate electrostatic interactions with [Ni(OH)3W6O18(OCH2)3CCH2OH]4–. PMID:27355393

  13. Structure of the puf operon of the obligately aerobic, bacteriochlorophyll alpha-containing bacterium Roseobacter denitrificans OCh114 and its expression in a Rhodobacter capsulatus puf puc deletion mutant.

    PubMed Central

    Kortlüke, C; Breese, K; Gad'on, N; Labahn, A; Drews, G

    1997-01-01

    Roseobacter denitrificans (Erythrobacter species strain OCh114) synthesizes bacteriochlorophyll a (BChl) and the photosynthetic apparatus only in the presence of oxygen and is unable to carry out primary photosynthetic reactions and to grow photosynthetically under anoxic conditions. The puf operon of R. denitrificans has the same five genes in the same order as in many photosynthetic bacteria, i.e., pufBALMC. PufC, the tetraheme subunit of the reaction center (RC), consists of 352 amino acids (Mr, 39,043); 20 and 34% of the total amino acids are identical to those of PufC of Chloroflexus aurantiacus and Rubrivivax gelatinosus, respectively. The N-terminal hydrophobic domain is probably responsible for anchoring the subunit in the membrane. Four heme-binding domains are homologous to those of PufC in several purple bacteria. Sequences similar to pufQ and pufX of Rhodobacter capsulatus were not detected on the chromosome of R. denitrificans. The puf operon of R. denitrificans was expressed in trans in Escherichia coli, and all gene products were synthesized. The Roseobacter puf operon was also expressed in R. capsulatus CK11, a puf puc double-deletion mutant. For the first time, an RC/light-harvesting complex I core complex was heterologously synthesized. The strongest expression of the R. denitrificans puf operon was observed under the control of the R. capsulatus puf promoter, in the presence of pufQ and pufX and in the absence of pufC. Charge recombination between the primary donor P+ and the primary ubiquinone Q(A)- was observed in the transconjugant, showing that the M and L subunits of the RC were correctly assembled. The transconjugants did not grow photosynthetically under anoxic conditions. PMID:9286973

  14. Structural consequences of the one-electron reduction of d4 [Mo(CO)2(eta-PhC[triple bond]CPh)Tp']+ and the electronic structure of the d5 radicals [M(CO)L(eta-MeC[triple bond]CMe)Tp'] {L = CO and P(OCH2)3CEt}.

    PubMed

    Adams, Christopher J; Bartlett, Ian M; Boonyuen, Supakorn; Connelly, Neil G; Harding, David J; Hayward, Owen D; McInnes, Eric J L; Orpen, A Guy; Quayle, Michael J; Rieger, Philip H

    2006-07-28

    Reduction of [M(CO)2(eta-RC[triple bond]CR')Tp']X {Tp' = hydrotris(3,5-dimethylpyrazolyl)borate, M = Mo, X = [PF6]-, R = R' = Ph, C6H4OMe-4 or Me; R = Ph, R' = H; M = W, X = [BF4]-, R = R' = Ph or Me; R = Ph, R' = H} with [Co(eta-C5H5)2] gave paramagnetic [M(CO)2(eta-RC[triple bond]CR')Tp'], characterised by IR and ESR spectroscopy. X-Ray structural studies on the redox pair [Mo(CO)2(eta-PhC[triple bond]CPh)Tp'] and [Mo(CO)2(eta-PhC[triple bond]CPh)Tp'][PF6] showed that oxidation is accompanied by a lengthening of the C[triple bond]C bond and shortening of the Mo-C(alkyne) bonds, consistent with removal of an electron from an orbital antibonding with respect to the Mo-alkyne bond, and with conversion of the alkyne from a three- to a four-electron donor. Reduction of [Mo(CO)(NCMe)(eta-MeC[triple bond]CMe)Tp'][PF6] with [Co(eta-C5H5)2] in CH2Cl2 gives [MoCl(CO)(eta-MeC[triple bond]CMe)Tp'], via nitrile substitution in [Mo(CO)(NCMe)(eta-MeC[triple bond]CMe)Tp'], whereas a similar reaction with [M(CO){P(OCH2)3CEt}(eta-MeC[triple bond]CMe)Tp']+ (M = Mo or W) gives the phosphite-containing radicals [M(CO){P(OCH2)3CEt}(eta-MeC[triple bond]CMe)Tp']. ESR spectroscopic studies and DFT calculations on [M(CO)L(eta-MeC[triple bond]CMe)Tp'] {M = Mo or W, L = CO or P(OCH2)3CEt} show the SOMO of the neutral d5 species (the LUMO of the d4 cations) to be largely d(yz) in character although much more delocalised in the W complexes. Non-coincidence effects between the g and metal hyperfine matrices in the Mo spectra indicate hybridisation of the metal d-orbitals in the SOMO, consistent with a rotation of the coordinated alkyne about the M-C2 axis.

  15. {sup 203,205}Tl NMR Studies of Crystallographically Characterized Thallium Alkoxides. X-Ray Structures of [Tl(OCH{sub 2}CH{sub 3})]4 and [Tl(OAr)]{sub infinity} where OAr = OC{sub 6}H{sub 3}(Me){sub 2}-2,6 and OC{sub 6}H{sub 3}(Pr{sup i}){sub 2}-2,6

    SciTech Connect

    ZECHMANN,CECILIA A.; BOYLE,TIMOTHY J.; PEDROTTY,DAWN M.; ALAM,TODD M.; LANG,DAVID P.; SCOTT,BRIAN L.

    2000-07-25

    [Tl(OCH{sub 2}CH{sub 3})]{sub 4}, (1) was reacted with excess HOR to prepare a series of [Tl(OR)]{sub n} where OR= OCHMe{sub 2} (2, n = 4), OCMe{sub 3} (3, n = 4), OCH{sub 2}CMe{sub 3} (4, n = 4), OC{sub 6}H{sub 3}(Me){sub 2}-2,6 (5, n = {infinity}), and OC{sub 6}H{sub 3}(Pr{sup i}){sub 2}-2,6 (6, n = {infinity}). Single crystal X-ray diffraction was used to determine the structure of compounds ligated by more sterically demanding ligands. Compound 4 was found to adopt a cubane structure, while 5 and 6 formed linear polymeric structures. These compounds were additionally characterized by {sup 203,205}Tl solution and {sup 205}Tl solid state NMR. Compounds 1--4 were found to remain intact in solution while the polymeric species, 5 and 6, appeared to be fluxional. While variations in the solution and solid state structures for the tetrameric [Tl(OR)]{sub 4} and polymeric [Tl(OAr)]{sub {infinity}} may be influenced by the steric hindrance of their respective ligands, the covalency of the species is believed to be more an effect of the parent alcohol acidity.

  16. Vanadium complexes of the N(CH2CH2S)3(3-) and O(CH2CH2S)2(2-) ligands with coligands relevant to nitrogen fixation processes.

    PubMed

    Davies, S C; Hughes, D L; Janas, Z; Jerzykiewicz, L B; Richards, R L; Sanders, J R; Silverston, J E; Sobota, P

    hydrolysis and to [V(NS3)(NCPh3)] (11) by reaction with ClCPh3. Compound 10 is converted into 1 by [NMe4]OH and to [V(NS3)NLi(THF)2] (12) by LiNPri in THF. A further range of imido complexes [V(NS3)(NR4)] (R4 = C6H4Y-4 where Y = H (13a), OMe (13b), Me (13c), Cl (13d), Br (13e), NO2 (13f); R4 = C6H4Y-3, where Y = OMe (13g); Cl (13h); R4 = C6H3Y2-3,4, where Y = Me (13i); Cl (13j); R4 = C6H11 (13k)) has been prepared by reaction of 1 with R4NCO. The precursor complex [V(OS2)O(dipp)] (14) [OS2(2-) = O(CH2CH2S)2(2-)] has been prepared from [VO(OPri)3], Hdipp, and OS2H2. It reacts with NH2NMe2 to give [V(OS2)(NNMe2)(dipp)] (15) and with N3SiMe3 to give [V(OS2)(NSiMe3)(dipp)] (16). A second oxide precursor, formulated as [V(OS2)1.5O] (17), has also been obtained, and it reacts with SiMe3NHNMe2 to give [V(OS2)(NNMe2)(OSiMe3)] (18). The X-ray crystal structures of the complexes 2b, 2c, 4, 6, 7a, 8a, 9, 10, 13d, 14, 15, 16, and 18 have been determined, and the 51V NMR and other spectroscopic parameters of the complexes are discussed in terms of electronic effects.

  17. Theoretical insight into OH- and Cl-initiated oxidation of CF3OCH(CF3)2 and CF3OCF2CF2H & fate of CF3OC(X•)(CF3)2 and CF3OCF2CF2X• radicals (X=O, O2)

    PubMed Central

    Bai, Feng-Yang; Ma, Yuan; Lv, Shuang; Pan, Xiu-Mei; Jia, Xiu-Juan

    2017-01-01

    In this study, the mechanistic and kinetic analysis for reactions of CF3OCH(CF3)2 and CF3OCF2CF2H with OH radicals and Cl atoms have been performed at the CCSD(T)//B3LYP/6-311++G(d,p) level. Kinetic isotope effects for reactions CF3OCH(CF3)2/CF3OCD(CF3)2 and CF3OCF2CF2H/CF3OCF2CF2D with OH and Cl were estimated so as to provide the theoretical estimation for future laboratory investigation. All rate constants, computed by canonical variational transition state theory (CVT) with the small-curvature tunneling correction (SCT), are in reasonable agreement with the limited experimental data. Standard enthalpies of formation for the species were also calculated. Atmospheric lifetime and global warming potentials (GWPs) of the reaction species were estimated, the large lifetimes and GWPs show that the environmental impact of them cannot be ignored. The organic nitrates can be produced by the further oxidation of CF3OC(•)(CF3)2 and CF3OCF2CF2• in the presence of O2 and NO. The subsequent decomposition pathways of CF3OC(O•)(CF3)2 and CF3OCF2CF2O• radicals were studied in detail. The derived Arrhenius expressions for the rate coefficients over 230–350 K are: k T(1) = 5.00 × 10−24T3.57 exp(−849.73/T), k T(2) = 1.79 × 10−24T4.84 exp(−4262.65/T), kT(3) = 1.94 × 10−24 T4.18 exp(−884.26/T), and k T(4) = 9.44 × 10−28T5.25 exp(−913.45/T) cm3 molecule−1 s−1. PMID:28067283

  18. Theoretical insight into OH- and Cl-initiated oxidation of CF3OCH(CF3)2 and CF3OCF2CF2H & fate of CF3OC(X•)(CF3)2 and CF3OCF2CF2X• radicals (X=O, O2)

    NASA Astrophysics Data System (ADS)

    Bai, Feng-Yang; Ma, Yuan; Lv, Shuang; Pan, Xiu-Mei; Jia, Xiu-Juan

    2017-01-01

    In this study, the mechanistic and kinetic analysis for reactions of CF3OCH(CF3)2 and CF3OCF2CF2H with OH radicals and Cl atoms have been performed at the CCSD(T)//B3LYP/6-311++G(d,p) level. Kinetic isotope effects for reactions CF3OCH(CF3)2/CF3OCD(CF3)2 and CF3OCF2CF2H/CF3OCF2CF2D with OH and Cl were estimated so as to provide the theoretical estimation for future laboratory investigation. All rate constants, computed by canonical variational transition state theory (CVT) with the small-curvature tunneling correction (SCT), are in reasonable agreement with the limited experimental data. Standard enthalpies of formation for the species were also calculated. Atmospheric lifetime and global warming potentials (GWPs) of the reaction species were estimated, the large lifetimes and GWPs show that the environmental impact of them cannot be ignored. The organic nitrates can be produced by the further oxidation of CF3OC(•)(CF3)2 and CF3OCF2CF2• in the presence of O2 and NO. The subsequent decomposition pathways of CF3OC(O•)(CF3)2 and CF3OCF2CF2O• radicals were studied in detail. The derived Arrhenius expressions for the rate coefficients over 230–350 K are: k T(1) = 5.00 × 10‑24T3.57 exp(‑849.73/T), k T(2) = 1.79 × 10‑24T4.84 exp(‑4262.65/T), kT(3) = 1.94 × 10‑24 T4.18 exp(‑884.26/T), and k T(4) = 9.44 × 10‑28T5.25 exp(‑913.45/T) cm3 molecule‑1 s‑1.

  19. Energetics of the O-H bond and of intramolecular hydrogen bonding in HOC6H4C(O)Y (Y = H, CH3, CH2CH=CH2, C[triple bond]CH, CH2F, NH2, NHCH3, NO2, OH, OCH3, OCN, CN, F, Cl, SH, and SCH3) compounds.

    PubMed

    Bernardes, Carlos E S; Minas da Piedade, Manuel E

    2008-10-09

    The energetics of the phenolic O-H bond in a series of 2- and 4-HOC 6H 4C(O)Y (Y = H, CH3, CH 2CH=CH2, C[triple bond]CH, CH2F, NH2, NHCH 3, NO2, OH, OCH3, OCN, CN, F, Cl, SH, and SCH3) compounds and of the intramolecular O...H hydrogen bond in 2-HOC 6H 4C(O)Y, was investigated by using a combination of experimental and theoretical methods. The standard molar enthalpies of formation of 2-hydroxybenzaldehyde (2HBA), 4-hydroxybenzaldehyde (4HBA), 2'-hydroxyacetophenone (2HAP), 2-hydroxybenzamide (2HBM), and 4-hydroxybenzamide (4HBM), at 298.15 K, were determined by micro- or macrocombustion calorimetry. The corresponding enthalpies of vaporization or sublimation were also measured by Calvet drop-calorimetry and Knudsen effusion measurements. The combination of the obtained experimental data led to Delta f H m (o)(2HBA, g) = -238.3 +/- 2.5 kJ.mol (-1), DeltafHm(o)(4HBA, g) = -220.3 +/- 2.0 kJ.mol(-1), Delta f H m (o)(2HAP, g) = -291.8 +/- 2.1 kJ.mol(-1), DeltafHm(o)(2HBM, g) = -304.8 +/- 1.5 kJ.mol (-1), and DeltafHm(o) (4HBM, g) = -278.4 +/- 2.4 kJ.mol (-1). These values, were used to assess the predictions of the B3LYP/6-31G(d,p), B3LYP/6-311+G(d,p), B3LYP/aug-cc-pVDZ, B3P86/6-31G(d,p), B3P86/6-311+G(d,p), B3P86/aug-cc-pVDZ, and CBS-QB3 methods, for the enthalpies of a series of isodesmic gas phase reactions. In general, the CBS-QB3 method was able to reproduce the experimental enthalpies of reaction within their uncertainties. The B3LYP/6-311+G(d,p) method, with a slightly poorer accuracy than the CBS-QB3 approach, achieved the best performance of the tested DFT models. It was further used to analyze the trends of the intramolecular O...H hydrogen bond in 2-HOC 6H 4C(O)Y evaluated by the ortho-para method and to compare the energetics of the phenolic O-H bond in 2- and 4-HOC 6H 4C(O)Y compounds. It was concluded that the O-H bond "strength" is systematically larger for 2-hydroxybenzoyl than for the corresponding 4-hydroxybenzoyl isomers mainly due to the presence of

  20. Smabarnens Kultur-Och Mediebarometer. (Barometer of Children's Cultural Activity).

    ERIC Educational Resources Information Center

    Filipson, Leni; Schyller, Ingela

    This is the first of a planned series of investigations of the media habits and other cultural activities of 3- to 8-year-old Swedish children. Diagrams show the percent of children who use the various media on an average day and the frequency of their participation in such activities as visits to the theater, museum, or library. The amount of…

  1. Synthesis, characterization, structural and biological aspects of copper(II) dithiocarbamate complexes - Part II, [Cu{S2CN(Me)(R1)}2], [Cu{S2CN(Me)(R2)}2] and [Cu{S2CN(R3)(R4)}2] {R1 = CH2CH(OMe)2, R2 = 2-methyl-1,3-dioxolane, R3 = CH2(CH2)2NCHPhOCH2Ph and R4 = CH2CH2OH}

    NASA Astrophysics Data System (ADS)

    Ferreira, Isabella P.; de Lima, Geraldo M.; Paniago, Eucler B.; Takahashi, Jacqueline A.; Krambrock, Klaus; Pinheiro, Carlos B.; Wardell, James L.; Visentin, Lorenzo C.

    2013-09-01

    Three new copper(II) dithiocarbamates (DTC), [Cu{S2CN(Me)(R1)}2] (1), [Cu{S2CN(Me)(R2)}2] (2) and [Cu{S2CN(R3)(R4)}2] (3) with R1 = CH2CH(OMe)2, R2 = 2-methyl-1,3-dioxolane, R3 = CH2(CH2)2NCHPhOCH2Ph and R4 = CH2CH2OH, have been synthesized and characterized by different spectroscopic techniques. Complexes (1) and (2) display typical EPR spectra for separated Cu(II) centers, and the spectrum of (3) is characteristic of two magnetically coupled Cu(II) ions with S = 1. The X-ray crystallographic determination has shown that complexes (1) and (2) crystallise in the triclinic and monoclinic systems. In addition both complexes are monomers in which the geometry at each Cu(II) is square planar. The in vitro antimicrobial activity of the sodium salts of ligands, and of the Cu(II)-DTC complexes have been screened against Aspergillus flavus, Aspergillus niger, Aspergillus parasiticus, Penicillium citrinum and Curvularia senegalensis, as well as Gram positive and Gram negative bacteria. Finally, the toxic effects of complexes (1)-(3) were performed using Chlorella vulgaris.

  2. Kop- och saljsystem inom barnomsorgen: Konsekvenser for Personal, Foraldrar och barn (A New Charging System in Child Care: Consequences for Personnel, Parents, and Children).

    ERIC Educational Resources Information Center

    Ekholm, Bodil; Ellstrom, Eva

    The aim of this study was to examined the impact of a new charging system in child care in two different Swedish municipalities, on personnel, parents, and children. Four day care centers situated in different socioeconomic areas were studied. A qualitative approach was used, and data were collected by means of interviews and a questionnaire.…

  3. Dagliga Separationer och Tidig Daghemsstart (Daily Separations and Early Entry into Day Care).

    ERIC Educational Resources Information Center

    Harsman, Ingrid

    The purpose of this thesis [Swedish language with English abstract and summary] was to study the reactions of infants when they started attending day care centers and to elucidate the process of adjustment. The theoretical perspective employed is the J. Bowlby/M. Ainsworth attachment theory. U. Bronfenbrenner's ecological theory of human…

  4. Library Work and Automation; A Summary of the Swedish Report "Biblioteksarbete och Automatisk Databehandling."

    ERIC Educational Resources Information Center

    Royal Library, Stockholm (Sweden).

    The work of the Committee on the use of automation in Swedish research libraries has differed from that of a normal study group by virtue of its heavy concentration on the practical aspects of library catalog work, the present status of which is the main theme of this report. The model presented implies total and simultaneous integration of all…

  5. Daghemsvistelse I Retrospektivt Perspektiv: En teori- och metodprovande studie (Daycare in Retrospect).

    ERIC Educational Resources Information Center

    Torstenson-Ed, Tullie

    This Swedish language report describes a preliminary study to test a retrospective life-history-inspired approach to studying children's experiences in a day care center, and whether children's experiences vary in different educational contexts and in relation to the teachers' experiences. The theoretical part of the study dealt with theories of…

  6. An Analysis of Textual Cohesion in a Passage from Maria Gripe's "Hugo och Josefin."

    ERIC Educational Resources Information Center

    Andersson, Erik

    Sentence-by-sentence analysis of factual or propositional cohesion in the first 29 lines of a Swedish children's story finds several sources of coherence that contribute to its cohesion. First, the text receives much coherence from its description of a single event, a situation where happenings are normal and expected. Second, a rather primitive…

  7. Aetervinning av faerg och ridaevatten med ultrafiltrering (recycling of paint and water curtains with ultrafiltration)

    SciTech Connect

    Fortkamp, U.; Allard, A.S.; Ekengren, O.

    1997-12-01

    Painting in spray booths causes overspray that is collected by a water curtain. The mixture of water and paint is commonly treated by means of precipitation. By means of this method, water can be used again but a paint sludge is created. Within this project, it was investigated how the paint as well as the water can be recycled. Separation by membrane filtration was tested for different paints in laboratory scale (0.2 liter volume). It was possible to separate all tested paints from the water and to concentrate it. At large scale (15 to 75 liters volume), an emulsion paint and a dispersion paint were tested. Under the tested conditions, it was slightly easier to concentrate the emulsion paint than the dispersion paint. It was possible to concentrate the paints to the original dry substance percentage. An important aspect of membrane filtration is cleaning of the membrane when the performance decreases. It was possible to clean all the tested membranes, but in many cases it was difficult. A ceramic membrane and a membrane of polyaramide showed the best results with regard to flux and cleaning of the membrane under the tested conditions. During the performance of the project two new applications of membrane filtration of paint were found. The method can be used for waste minimization by only separating the paint in an easy way at low costs. A third application is treating cleaning water from paint manufacturing.

  8. Sma Barn Pa Daghem: En studie av personalens samspel med barn och foraldrar vid lamning, hamtning och fri lek (Infants at Day Care: A Study of Staff Interaction with Children and Their Parents during Leaving, Collecting and Free Play).

    ERIC Educational Resources Information Center

    Lothigius, Anita Holmstedt

    This thesis presents a picture of how staff interact with infants (age group 1-3 years old) and parents at three day care centers. The study focused on the situations of leaving and collecting the children and the children's time of free play both in and outdoors. The theoretical content has an attachment/psycho-dynamical perspective with emphasis…

  9. Daghemsklimat: Bakgrund, syfte och matinstrument. (The Climate of Day-Care Centers: Theoretical Backgrounds and Methods of Measurement).

    ERIC Educational Resources Information Center

    Ekholm, Bodil; And Others

    Using a new approach to studying day care centers, this study focused on the total climate of the day care center and the climate's effects on children's social and emotional behavior. A theoretical model for analyzing day care climate is presented. The model includes variables such as job satisfaction, work atmosphere, interactions between…

  10. Speciallararens Kunskaper Och Kompetens: Intervjuer med tio speciallarare (The Special Teacher's Knowledge and Competence: Interviews with Ten Special Teachers).

    ERIC Educational Resources Information Center

    Vernersson, Inga-Lill

    This thesis reports on a study in which 10 Swedish special education teachers were interviewed concerning the following six topics: (1) personal background and choice of a career; (2) professional knowledge; (3) the role of a special education teacher; (4) educational goals and methods; (5) cooperation; and (6) thoughts about the future.…

  11. Inventory Manager’s Workstation for the Aviation Supply Office

    DTIC Science & Technology

    1988-12-01

    PHANTOM USER LOGIN MACRO ............... 148 APPENDIX H INVENTORY MANAGEMENT MACROS .............. 165 LIST OF REFERENCES...support the DSS software. Each of 42 MINE The Connectivity DcM ionnDecision Guide moreThenFile exchange foer spephera t no only? no Disk/cartrIdge yes...The Sun 3/160 executes a batch program that logs in a phantom user on the server. The phantom user enters ALIS. (2:30 am, nightly) * As the phantom

  12. Att Tolka Barns Signaler: Gravt utvecklingsstorda flerhandikappade barns lek och kommunikation (To Interpret Childrens' Signals: Play and Communication in Profoundly Mentally Retarded and Multiply Handicapped Children).

    ERIC Educational Resources Information Center

    Brodin, Jane

    Written in Swedish with an English-language summary, this report describes a study which examined the interaction between mothers or caregivers and their children with profound mental retardation and multiple disabilities, particularly looking at the function of play in communicative interaction. The six children all had five or six handicaps in…

  13. Knowledge and Life-Experiences: Finland Seen through Its Libraries and Information Services = Kunskap och Upplevelser: Finland som BDI-land.

    ERIC Educational Resources Information Center

    Laaksovirta, Tuula H.; Haavisto, Tuula

    This illustrated publication, printed in both English and Finnish, describes Finland's libraries and information services. Topics covered include: (1) library users; (2) the conceptual role of the library; (3) the growth and development of the library system through Finland's agrarian, industrial, and budding infotech social phases; (4) the…

  14. Still Picture Telephones for Persons with Profound Mental Retardation. Telematik och Handikapp, Rapport 92:9 (Telematics and Disability, Report 92:9).

    ERIC Educational Resources Information Center

    Brodin, Jane; Bjorck-Akesson, Eva

    This project studied the use of still picture telephones by four Swedish adults (ages 25-45) with profound mental retardation and additional severe disabilities. After 5 to 6 months of subjects employing still picture telephones on a regular basis in their daily lives, relatives, staff from group homes, and other caregivers completed…

  15. 12 Daghem: Beskrivning av uppfostringsklimat och sociala relationer (Twelve Day Care Centers: A Multisite Comparison of Day-Care Climate and Social Relations).

    ERIC Educational Resources Information Center

    Ekholm, Bodil; Hedin, Anna

    Twelve day care centers in a Swedish commune were systematically observed. Centers were selected on the basis of responses to a questionnaire on attitudes about upbringing which was answered by all the personnel at the 104 day care centers in the commune. Four of the selected centers represented a so-called "present-focused" upbringing…

  16. Daghemsklimat: Uppfostringsattityder, engagemang och kanslor infor arbetet hos daghemspersonal. (Attitudes of Child-Rearing, Engagements and Feelings towards Work by Personnel at Day-Care Centers).

    ERIC Educational Resources Information Center

    Jonsson, Arne

    Approximately 900 employees in the day care centers in one Swedish commune answered a questionnaire measuring child rearing attitudes and personnel's engagement and feelings concerning their work with the children. The child rearing attitudes were described as either "present-focused" or "future-focused." Of particular interest…

  17. Principles of Biochemistry, Second Edition by H. Robert Horton, Laurence A. Moran, Raymond S. Ochs, J. David Rawn, K. Gray Scrimgeour

    NASA Astrophysics Data System (ADS)

    Voige, William H.

    1997-02-01

    Prentice Hall: Upper Saddle River, NJ, 1996. xxix + 801 pp. Figs. and tables. 22.4 x 28.4 cm. This book follows the format that has become standard for biochemistry texts. Sections begin with short declarative statements of principles that are explained concisely in the following paragraphs. The best chapters proceed in a straightforward and logical manner. The lipids chapter is exemplary. A discussion of molecular structure, beginning with fatty acids, is followed by membrane structure, transport, and signal transduction.

  18. Fortursbarn och "vanliga" barn pa tolv daghem: Jamforande observationer. (Mainstreamed Children and "Ordinary" Children in Twelve Day-Care Centers: An Observational Study).

    ERIC Educational Resources Information Center

    Ekholm, Bodil; Hedin, Anna

    Observations of one mainstreamed child and one "ordinary child" at each of 12 day care centers were compared. Five of the 12 mainstreamed children were mentally retarded, and seven had a slight developmental retardation mainly due to deprivation. Observations of 10-minute duration, totaling 4 hours and dispersed across 7 days, focused on…

  19. Proposal of New Precursors for Plasma-Enhanced Chemical Vapor Deposition of SiOCH Low-k Films with Plasma Damage Resistance

    NASA Astrophysics Data System (ADS)

    Yoshi Ohashi,; Nobuo Tajima,; Yonghua Xu,; Takeshi Kada,; Shuji Nagano,; Hideharu Shimizu,; Satoshi Hasaka,

    2010-05-01

    We propose new precursors for bulk low-k films with plasma damage resistance. Our newly designed precursors contain long-chain hydrocarbon groups such as i-butyl and n-propyl groups. Using these precursors, we successfully produced films containing Si-CH2-Si groups by plasma-enhanced chemical vapor deposition (PECVD). The plasma damage resistance of these films under NH3 plasma treatment was studied. It was found that the increase in the k-value (Δ k) is smaller in films with more Si-CH2-Si groups.

  20. Proposal of New Precursors for Plasma-Enhanced Chemical Vapor Deposition of SiOCH Low-k Films with Plasma Damage Resistance

    NASA Astrophysics Data System (ADS)

    Ohashi, Yoshi; Tajima, Nobuo; Xu, Yonghua; Kada, Takeshi; Nagano, Shuji; Shimizu, Hideharu; Hasaka, Satoshi

    2010-05-01

    We propose new precursors for bulk low-k films with plasma damage resistance. Our newly designed precursors contain long-chain hydrocarbon groups such as i-butyl and n-propyl groups. Using these precursors, we successfully produced films containing Si-CH2-Si groups by plasma-enhanced chemical vapor deposition (PECVD). The plasma damage resistance of these films under NH3 plasma treatment was studied. It was found that the increase in the k-value (Δk) is smaller in films with more Si-CH2-Si groups.

  1. Li[B(OCH2CF3)4]: synthesis, characterization and electrochemical application as a conducting salt for LiSB batteries.

    PubMed

    Rohde, Michael; Eiden, Philipp; Leppert, Verena; Schmidt, Michael; Garsuch, Arnd; Semrau, Guenter; Krossing, Ingo

    2015-02-23

    A new Li salt with views to success in electrolytes is synthesized in excellent yields from lithium borohydride with excess 2,2,2-trifluorethanol (HOTfe) in toluene and at least two equivalents of 1,2-dimethoxyethane (DME). The salt Li[B(OTfe)4 ] is obtained in multigram scale without impurities, as long as DME is present during the reaction. It is characterized by heteronuclear magnetic resonance and vibrational spectroscopy (IR and Raman), has high thermal stability (Tdecomposition >271 °C, DSC) and shows long-term stability in water. The concentration-dependent electrical conductivity of Li[B(OTfe)4 ] is measured in water, acetone, EC/DMC, EC/DMC/DME, ethyl acetate and THF at RT In DME (0.8 mol L(-1) ) it is 3.9 mS cm(-1) , which is satisfactory for the use in lithium-sulfur batteries (LiSB). Cyclic voltammetry confirms the electrochemical stability of Li[B(OTfe)4 ] in a potential range of 0 to 4.8 V vs. Li/Li(+) . The performance of Li[B(OTfe)4 ] as conducting salt in a 0.2 mol L(-1) solution in 1:1 wt % DME/DOL is investigated in LiSB test cells. After the 40th cycle, 86 % of the capacity remains, with a coulombic efficiency of around 97 % for each cycle. This indicates a considerable performance improvement for LiSB, if compared to the standard Li[NTf2 ]/DOL/DME electrolyte system.

  2. [A Pichia pastoris with alpha-1, 6-mannosyltransferases deletion and its use in expression of HSA/GM-CSF chimera].

    PubMed

    Wang, Yue; Gong, Xin; Chang, Shao-Hong; Liu, Bo; Song, Miao; Huang, Hai-Hua; Wu, Jun

    2007-09-01

    Yeast is a widely used host for recombinant protein expression. However, glycoproteins derived from yeast contain N-glycan of high mannose type and are usually hyperglycosylated. alpha-1,6-mannosyltransferases gene (och1) encodes the enzyme that initiates the first step of out-chain elongation of high mannose type N-glycan in yeast, which is different from that in human. So, a high efficient method to knockout target gene by two-step recombination was established and was used to delete och1. In the first recombinant, a plasmid with och1::ADE1 and ura3 gene was linearized in the downstream of och1 and inserted to the och1 site of P. pastoris genome, where the upstream and downstream of och1 were duplicated. In the second recombinant, the duplicated fragments of och1 were exchanged and the och1 deletion strains were selected on the plates containing 5-FOA, but no adenine. Then the och1 deletion strain was applied to express an human serum albumin (HSA) granulocyte-macrophage colony-stimulating factor (GM-CSF) chimera. Different with the hyperglycosylated HSA/GM-CSF chimera expressed in wild type P. pastoris, the chimera expressed in the och1 deletion strain, contained smaller N-glycan. The results suggested that the och1 mutant yeast may be more suitable for production of recombinant glycoproteins. And the och 1 deletion strain could be used for further re-engineering to produce complex human glycoproteins.

  3. Studenters fritids--och motionsvanor i Umea och Madison. Ett bidrag till forstaelsen av Pierre Bourdieus vetenskapliga metodologi. Akademiska avhanlingar, Pedagogiska institutionen Nr. 58 (Leisure and Exercise Habits among Students in Umea and Madison. A Contribution to the Understanding of Pierre Bourdieu's Scientific Methodology. Academic Dissertation, Faculty of Social Sciences No. 58).

    ERIC Educational Resources Information Center

    Lofgren, Kent

    This study, presented in Swedish with an English summary, analyzed differences between student groups at Umea University, Sweden, and the University of Wisconsin-Madison in terms of study situations, experiences of the university environment, exercise and sports activities, and the connections between study and leisure time activities. The study…

  4. Komvux-Proven i Engelska VT 1989: Jamforelser mellan Komvux och Gymnasieskolan i Fraga om Provresultat och Betyg. Rapport nr 1990:06. (National Standardized Tests in English in Adult Education 1989: Comparison between Adult and Upper Secondary Students Test Results and School Leaving Grades. Report No. 1990:06).

    ERIC Educational Resources Information Center

    Oscarson, Mats

    This report describes the results of adult education students and upper secondary school students on two recently introduced standardized English tests in Sweden. Comparisons of the results are made between these two categories of students because they are entitled to compete, on an equal basis, for admission into restricted intake programs of…

  5. Perspektiv pa Las och Skrivinlarning: En Litteraturstudie som Belyser Las och Skrivinlarning utifran Fyra Teoretiska Perspektiv Samt en Instrument-Provande Barnstudie (Perspectives on Learning To Read and Write: Literature Review on Reading and Writing Acquisition through Examination of Four Theroretical Perspectives and Attitude Measures of Preschool Children).

    ERIC Educational Resources Information Center

    Fahlen, Rose-Marie

    This report focuses on the processes of learning to read and write in the initial phases. Two studies are presented. The first is a review of four theoretical approaches, including Jerome Bruner's representation theory, and theories of concept learning, metacognition, and metalinguistic awareness. The purpose of the literature study was to examine…

  6. Hogskoleprovet: "En Andra Chans" Eller "Ytterligare en Oppen Dorr." Fem gymnasielarare om egna och gymnasieelevers synpunkter pa betyg och hogskoleprovet (Effects in Upper Secondary School of a More Extensive Use of the Higher Education Selection Test in the Admission to Higher Education).

    ERIC Educational Resources Information Center

    Gustavsson, Maria

    This study was designed to examine the attitudes of teachers and students in Swedish upper secondary schools in regard to the use of higher education scholastic aptitude test (SAT) scores in lieu of secondary school grades to gain entrance into higher education programs. Since 1991 applicants to higher education have been allowed to take the…

  7. Spectroscopy of new Sm(III) orange emitting phosphors of the type Na[Sm(SP)4], Na[Sm(WO)4] (where SP = C6H5S(O)2NP(O)(OCH3)2-; WO = CCl3C(O)NP(O)(OCH3)2-) and the polymeric materials obtained on their base

    NASA Astrophysics Data System (ADS)

    Cybińska, Joanna; Guzik, Małgorzata; Gerasymchuk, Yuriy; Trush, Victor A.; Lisiecki, Radosław; Legendziewicz, Janina

    2017-01-01

    Among a wide variety of solid state materials lanthanide beta-diketonates, their derivatives and polymeric materials based on them have become essential for advance technologies. Thus they are the subject of extensive spectroscopic studies. Using appropriate lanthanide chelates for the emission layer one can achieve electroluminescence covering the spectrum from blue to infrared. Moreover, compounds with proper chromophores can be the best way to excite and enhance the emission although the f-f transitions have forbidden character. Two types of new Sm(III) chelates; phosphoro and sulfono-derivatives of beta-diketones and polymeric materials on their base were obtained and characterized by the high resolution photoluminescence spectroscopy at 293, 77 and 4 K, as well as by luminescence decay times. Those new type of phosphors shows strong orange emission after excitation at 404 nm Sm(III) states and 280 nm ligand bands. Radiative transition probabilities were calculated from absorption spectra and Judd- Ofelt parameters evaluated. Effects of the temperature, rigidity of polymeric lattice and the energy of excitation on intensities of the Sm(III) fluorescence were studied. The paths of energy transfer are analysed and mechanism of this process is proposed.

  8. Cost Effectiveness Analysis, A DTIC Bibliography.

    DTIC Science & Technology

    1980-07-01

    FOer Cot. *Otical materials. -Life cycle costs. l: aircraft. SiW.alDESCRIPTORS: *D~pa-tosnt of Defense. -Cost nrcssnZ. Cacl-es. Czt *.Cal ae’eludef...Kennebunkportc Maine, on 11-13 June DESCRIPTIVE NOTE: Final reot.. 1974. (U) MAY 74 8P Genet.Russell M. REPT. NO. ASIC -74-024 DESCRIPTIVE NOTE: Final...Fcrce egviDTent (U) The paper deals withi the’so- czt ).leo siocretar. IDEN4TIFIERS: Life cycle costing. *Logistics problem, i.e. witn’the probleśof

  9. Molecular Basis for the Toxicity of Schweinfurthins to Breast Cancer cells

    DTIC Science & Technology

    2005-05-01

    OCH 3 DIPEA, OCH3 nBuLi,o OCH3 HO.MOMI MOMO geranyl bromide Br 95% Br 19 OH 20 OMOM 21 OMOM 63%j AD-mix-a, MeSO 2 NH 2 OCH3 OCH3 MOMO 1) MsCI, TEA...OH MOMO 0,, I 2) K2CO 3 , MeOH OMOM HO = OMOM 36%• F,0° [a]D = -649O 2250%)/IEDC, DMAP, OCH3 R-O-methylphenylacetic acid Ŕ OCHO Ph MOMO HO’ OH3...Gaumond, B. R.; closed in due course. Marsh, H. C. J. Med Chem. 2003, 46, 2697-2705. OMOM OMOM O=P(OEt)2 MOMO @ • MOMO . OMOM NaH, 15C5 OMOM N O1

  10. CCSD(T) study of the infrared spectrum of ethyl-methyl-ether isotopic varieties

    NASA Astrophysics Data System (ADS)

    Senent, M. L.; Ruiz, R.; Villa, M.; Domínguez-Gómez, R.

    2010-02-01

    Band positions for the infrared bands of various ethyl-methyl-ether isotopomers (CH 3CH 2OCH 2D, CH 2DCH 2OCH 3, CH 3CH 2OCD 3, CD 3CH 2OCH 3, CH 3CD 2OCH 3, CH 3CH 2O 13CH 3, 13CH 3CH 2OCH 3, and CH 313CH 2OCH 3) are determined using second order perturbation theory. For species showing G18 symmetry, band position are calculated variationally from a CCSD(T)/cc-pVTZ three-dimensional potential energy surface corrected vibrationally. Potential energy barriers, fundamental frequencies, and rotational constants for excited vibrational levels, are also provided. Calculated frequencies for CH 3CH 2OCD 3 confirm experimental assignments and our predictions for the most abundant isotopomer [4].

  11. Field Testing New Plot Designs and Methods for Determining Hydrophytic Vegetation during Wetland Delineations in the United States

    DTIC Science & Technology

    2014-03-01

    Engineers. Walter Ochs provided the ini- tial idea for evaluating the 80% approach based on differences in the standard deviation. Christy Everett and Jim...Godswire provided assistance in selecting sites to collect the CRREL data. Bruce Allen, Lindsey Lefevbre, Walter Ochs , Corinna Photos, Bill Sipple...vegetation determination (USACE 2010a). The 80.0% value was developed in 2005 (R. Lichvar and W. Ochs , unpublished data) by analyzing a national set of

  12. Improving Domain-specific Machine Translation by Constraining the Language Model

    DTIC Science & Technology

    2012-07-01

    of greater amounts of training data in the two models, especially in the target language model (Brants et al., 2007). Och (2005) reports findings...train with the largest language models (NIST, 2006). The highest scoring Arabic-English system used a 1-trillion-word language model ( Och , 2006...References Brants, T.; Popat, A. C.; Xu, P.; Och , F. J.; Dean, J. Large Language Models in Machine Translation. Joint Meeting of the Conference on Empirical

  13. Larande I Produktionssytem. En studie av operatorsarbete i hogautomatiserad process--och verkstadsindustri = Learning in Production Systems. A Study of Operator Work in Highly Automated Process and Manufacturing Industry. Linkoping Studies in Education and Psychology, No. 63.

    ERIC Educational Resources Information Center

    Davidson, Bo; Svedin, Per-Olof

    This study of the conditions of developmental on-the-job training and learning for operators in highly automated industries is written in Swedish but contains an English abstract and 18-page summary. The summary begins with the study objectives, which were to determine the following: (1) conditions of developmental on-the-job learning in highly…

  14. Fluid inclusions in the system H sub 2 O-CH sub 4 -NaCl-CO sub 2 from metasomatic tourmaline within the border unit of the Tanco zoned granitic pegmatite, S. E. Manitoba

    SciTech Connect

    Thomas, A.V.; Spooner, E.T. )

    1988-05-01

    Fluid inclusions from the tourmaline phase of alteration of the footwall amphibolite from the Tanco zoned granitic pegmatite lie in the system H{sub 2}O-CH{sub 4}-NaCl-CO{sub 2}. These inclusions contain a liquid and vapor phase at room temperature and develop a second liquid phase on cooling in the range {minus}77 to {minus}95{degree}C: the second liquid and the vapor are methane. Isochores for inclusions showing vapor phase (CH{sub 4}) homogenization were constructed from the equations of Jacobs and Kerrick (1981). The intersections of these isochores with the univariant melting curves for methane clathrate hydrates give estimates of salinity for the inclusions of between 7 and 10 equivalent wt.% NaCl, which are lower than those derived from measurement of the depression of the melting point of ice; a result consistent with salt exclusion by clathrate. The bulk composition of the fluid is estimated to be 91 mol.% H{sub 2}O, 6 mol.% CH{sub 4}, 2 equiv. mol.% NaCl and <1 mol.% CO{sub 2}. Total homogenization temperatures have a mean value of 371{degree}C {plus minus} 36{degree}C. Calculation of f{sub O2} from the bulk inclusion composition gives values near WI at these conditions which is unreasonably low for fluids derived from the pegmatite, which were probably between QFM and HM. The metasomatic fluids may have resulted from fluid mixing in the wall rock immediately adjacent to the pegmatite. The fluid derived from the pegmatite, a H{sub 2}O-CO{sub 2} fluid, introduced the B necessary to form tourmaline in the amphibolite. Supporting evidence is provided by pegmatite wall zone fluids with higher CH{sub 4} than the bulk of the pegmatite H{sub 2}O-CO{sub 2} fluids, suggesting marginal fluid contamination.

  15. Oxo Complexes of Tungstenocene via Oxidation of (W(Eta(5)-C5H5)2(OCH3) (CH3)) and Related Reactions: Synthesis, Structural Characterization, and Photodisproportionation of the Spin Paired d(1)-d(1) Oxo Bridged Dimer ((W(Eta(5)-C5H5)2(CH3))2(Mu-O))2(+) and Synthesis and Charaterization of the d(0) Terminal Oxo Complex (W(Eta(5)-C5H5)2(O)(CH3))(+)

    DTIC Science & Technology

    1993-02-15

    work was supported in part by the Office of Na\\ al Research We thank Dr . Steven Geib and Professor Bruce Foxman for helpful discusions of the X-ra...techniques or a Vacuum Atmospheres dr % box under an atmosphere of prepunfied nitrogen unless otherise noted Glass%%are wvas flame dncd under vacuum or...of Naval Research (2)" Dr . Richard W. Drisko (1) Chemistry Division, Code 1113 Naval Civil Engineering 800 North Quincy Street Laboratory Arlington

  16. Fluoxetine Hydrochloride Enhances In Vitro Susceptibility to Chloroquine in Resistant Plasmodium falciparum

    DTIC Science & Technology

    1992-12-01

    chloroquine- (12), ketotifen (1), tetrandrine (20, 21), and cyproheptadine susceptible clone D6 (50% inhibitory concentration [IC 5o], (16). !s3 ng/ml). IC... CYPROHEPTADINE KETOTIFEN N OCN3 HICO N ’IN ~~OCH3 NN H 0 OCH.3 TETRANDRINE FIG. 1. Structures of fluoxetine and other drugs that have been reported to

  17. COMPONENTS OF SURFACE AND SUBSURFACE CONNECTIVITY IN A LARGE OREGON (USA) RIVER--WHAT CAN BE RESTORED?

    EPA Science Inventory

    We conducted research on the Willamette River in western Oregon (USA) to determine the ecological functions of off-channel habitats (OCH). OCHs have declined in our 70 km study reach of the active floodplain since European settlement. Surface and subsurface connectivity between...

  18. ORGANONICKEL CHEMISTRY IN THE CATALYTIC HYDRODECHLORINATION OF POLYCHLOROBIPHENYLS (PCBS): LIGAND STERIC EFFECTS AND MOLECULAR STRUCTURE OF REACTION INTERMEDIATES. (R823526)

    EPA Science Inventory

    Abstract

    Soluble homogeneous organophosphorus¯¯nickel complexes have been used to detoxify polychlorinated biphenyls (PCBs) by catalyzed hydrodechlorination using NaBH2(OCH2CH2OCH3)2 as the hyd...

  19. Discourse Markers in Chinese Conversational Narrative

    ERIC Educational Resources Information Center

    Xiao, Yang

    2010-01-01

    This study examines the indexicality of discourse markers (DMs) in Chinese conversational narrative. Drawing upon theoretical and methodological principles related to narrative dimensions (Ochs & Capps, 2001), narrative desires (Ochs, 1997, 2004), and narrative positioning (Bamberg, 1997), this work proposes an integrated analytical framework for…

  20. Ecological Functions of Off-Channel Habitats of the Willamette River, Oregon, Database and Documentation (1997-2001)

    EPA Science Inventory

    The database from the Ecological Functions of Off-Channel Habitats of the Willamette River, Oregon project (OCH Project) contains data collected from 1997 through 2001 from multiple research areas of the project, and project documents such as the OCH Research Plan, Quality Assura...

  1. Atmospheric photooxidation of fluoroacetates as a source of fluorocarboxylic acids.

    PubMed

    Blanco, M B; Bejan, I; Barnes, I; Wiesen, P; Teruel, Mariano A

    2010-04-01

    A 1080 L environmental chamber with in situ FTIR spectroscopy detection was used to study the product distribution and the mechanism of the Cl-initiated photooxidation of a series of fluoroacetates. The gas-phase reactions of Cl atoms with ethyl trifluoroacetate (CF(3)C(O)OCH(2)CH(3)), methyl trifluoroacetate (CF(3)C(O)OCH(3)), and methyl difluoroacetate (CF(2)HC(O)OCH(3)) were investigated at 296 +/- 2 K and atmospheric pressure (approximately 760 Torr) of synthetic air. The fate of the fluoroalkoxy radicals formed in the reaction with Cl atoms mainly occurs through (i) an H-atom abstraction by reaction with O(2,) to produce the corresponding fluoroanhydride and (ii) an alpha-ester rearrangement via a five-membered ring intermediate to give the corresponding fluoroacetic acid. The yields of fluoroacids (CF(2)XC(O)OH, with X = H, F) obtained were as follows: 78 +/- 5, 23 +/- 2, and 30 +/- 5% for CF(3)C(O)OCH(2)CH(3), CF(3)C(O)OCH(3), and CF(2)HC(O)OCH(3,), respectively. Yields of OCH(2)CH(3), CF(3)C(O)OCH(3), and CF(2)HC(O)OCH(3), respectively. Formation of CF(2)O, with yield of 13 +/- 2% has been observed for the reaction of Cl with CF(2)HC(O)OCH(3). The measured yields are rationalized in terms of mechanisms consisting of competitive reaction channels for the radicals formed in the oxidation, that is, reaction with O(2), alpha-ester rearrangement and a decomposition pathway. The stability of the five-membered transition state of the alpha-ester rearrangement is correlated with the acid yields observed for the different fluoroacetates. Atmospheric implications, especially with regard to the fluorocarboxylic acid formation, are discussed.

  2. Tin(II) alkoxide hydrolysis products for use as base catalysts

    DOEpatents

    Boyle, Timothy J.

    2002-01-01

    Tin alkoxide compounds are provided with accessible electrons. The compounds are a polymeric tin alkoxide, [Sn(OCH.sub.2 C(CH.sub.3).sub.3).sub.2 ].sub.n, and the hydrolysis products Sn.sub.6 O.sub.4 (OCH.sub.2 C(CH.sub.3).sub.3).sub.4 and Sn.sub.5 O.sub.2 (OCH.sub.2 C(CH.sub.3).sub.3).sub.6. The hydrolysis products are formed by hydrolyzing the [Sn(OCH.sub.2 C(CH.sub.3).sub.3).sub.2 ].sub.n in a solvent with controlled amounts of water, between 0.1 and 2 moles of water per mole of the polymeric tin alkoxide.

  3. Theoretical Investigation of Mechanisms for the Gas-Phase Unimolecular Decomposition of DMMP

    NASA Astrophysics Data System (ADS)

    Yang, Li; Shroll, Robert M.; Zhang, Jiaxu; Lourderaj, U.; Hase, William L.

    2009-11-01

    All species involved in the multichannel decomposition of gas-phase dimethyl methylphosphonate (DMMP) were investigated by electronic structure calculations. Geometries for stationary structures along the reaction paths, were fully optimized with the MP2 method and the B3LYP and MPW1K DFT functionals, and the 6-31G*, 6-31++G**, and aug-cc-pVDZ basis sets. The geometries determined by the B3LYP and MPW1K functionals are in very good agreement with the MP2 values. Increasing the basis set size from 6-31G* to aug-cc-pVDZ does not significantly alter this result. Single point energy calculations were carried out with highly accurate but computationally more expensive CBS-QB3 theory. DMMP has three conformers, which lead to the four primary product channels, (O)P(CH2)(OCH3) + CH3OH, (O)P(CH3) (OCH3)(OH) + CH2, c-(O)P(CH3)OCH2 + CH3OH, and (O)P(CH3)(OCH3)(OCH) + H2. The first channel has the lowest energy barrier and is expected to be the most important pathway. It occurs via C-H and P-O bond cleavages accompanied by O-H bond formation. The other three channels have higher and similar energy barriers, and are expected to have smaller and similar rates. The product (O)P(CH3)(OCH3)(OCH) undergoes a secondary decomposition to form (OH)P(CH3)(OCH3) + CO.

  4. Improved oral bioavailability of 20(R)-25-methoxyl-dammarane-3β, 12β, 20-triol using nanoemulsion based on phospholipid complex: design, characterization, and in vivo pharmacokinetics in rats

    PubMed Central

    Zhang, Xiangrong; Zhang, Yi; Guo, Shuang; Bai, Feifei; Wu, Tong; Zhao, Yuqing

    2016-01-01

    The aim of the study was to improve the oral absorption of the compound 25-OCH3-PPD with poor hydrophilicity and lipophilicity. 25-OCH3-PPD-phospholipid complex was prepared by solvent evaporation, then characterized by differential scanning calorimetry, scanning electron microscopy, and infrared absorption spectroscopy. The aqueous solubility and oil–water partition coefficient were compared with the free compound. A nanoemulsion loaded with 25-OCH3-PPD-phospholipid complex was developed by dissolving the complex in water in the presence of hydrophilic surfactant under sonication. After oral administration of the nanoemulsion and the suspension of 25-OCH3-PPD in rats, the concentrations of 25-OCH3-PPD in plasma were determined by high-performance liquid chromatography–tandem mass spectrometry method. The results showed that the solubility of the complex in water and n-octanol was enhanced. The oil–water partition coefficient improved 1.7 times. Peak plasma concentration and area under the curve(0–24 h) of the nanoemulsion of 25-OCH3-PPD-phospholipid complex were higher than that of free compound by 3.9- and 3.5-folds. PMID:27877020

  5. Perspectives on Pentaerythritol Tetranitrate (PETN) Decomposition

    SciTech Connect

    Chambers, D; Brackett, C; Sparkman, D O

    2002-07-01

    This report evaluates the large body of work involving the decomposition of PETN and identifies the major decomposition routes and byproducts. From these studies it becomes apparent that the PETN decomposition mechanisms and the resulting byproducts are primarily determined by the chemical environment. In the absence of water, PETN can decompose through the scission of the O-NO{sup 2} bond resulting in the formation of an alkoxy radical and NO{sub 2}. Because of the relatively high reactivity of both these initial byproducts, they are believed to drive a number of autocatalytic reactions eventually forming (NO{sub 2}OCH{sub 2}){sub 3}CCHO, (NO{sub 2}OCH{sub 2}){sub 2}C=CHONO{sub 2}, NO{sub 2}OCH=C=CHONO{sub 2}, (NO{sub 2}OCH{sub 2}){sub 3}C-NO{sub 2}, (NO{sub 2}OCH{sub 2}){sub 2}C(NO{sub 2}){sub 2}, NO{sub 2}OCH{sub 2}C(NO{sub 2}){sub 3}, and C(NO{sub 2}){sub 4} as well as polymer-like species such as di-PEHN and tri-PEON. Surprisingly, the products of many of these proposed autocatalytic reactions have never been analytically validated. Conversely, in the presence of water, PETN has been shown to decompose primarily to mono, di, and tri nitrates of pentaerythritol.

  6. Synthesis, physicochemical analysis of two new hemilabile ether-phosphine ligands and their first stable bis-ether-phosphine/cobalt(II) tetrahedral complexes

    NASA Astrophysics Data System (ADS)

    Warad, Ismail; Barakat, Assem

    2017-04-01

    New tridentate ether-phosphine {P, 2O} and ether-phosphine oxide {OP, 2O} ligands with P and O donor-atoms have been synthesized starting from ClCH2CH(OCH3)2. The oxidation process of Ph2PCH2CH(OCH3)2 to its oxide derivative Ph2P(dbnd O)CH2CH(OCH3)2 was monitored by 31P NMR for the first time. The desired ligands and their Co(II) complexes structures were deduced from IR, EA, MS, NMR, UV-Vis., TG/DTG and XRD physical measurements. The tridentate chelating coordination behavior of the ether-phosphine wasn't detected leading only to the mono-dentate coordination mode through the phosphorous atoms to set up a X2Co[η1-Ph2PCH2CH(OCH3)2]2 as final isomer formula (X = Cl or Br). The Cl2Co[η1-Ph2PCH2CH(OCH3)2]2 isomer belongs to complex 1 was supported by single crystal measurement. Polar/non-polar intermolecular short contacts were detected by XRD and Hirshfeld surface theoretical analysis.

  7. Fluid inclusion volatile analysis by gas chromatography with photoionization/micro-thermal conductivity detectors: Applications to magmatic MoS sub 2 and other H sub 2 O-CO sub 2 and H sub 2 O-CH sub 4 fluids

    SciTech Connect

    Bray, C.J.; Spooner, E.T.C. )

    1992-01-01

    Eighteen fluid inclusion volatile peaks have been detected and identified from 1-2 g samples (quartz) by gas chromatography using heated on-line crushing, helium carrier gas, a single porous polymer column, two temperature programmed conditions for separate sample aliquots, micro-thermal conductivity (TCD) and photoionization detectors (PID), and off-line digital peak processing. In order of retention time these volatile peaks are: N{sub 2}, Ar, CO, CH{sub 4}, CO{sub 2}, C{sub 2}H{sub 4}, C{sub 2}H{sub 6}, C{sub 2}H{sub 2}, COS, C{sub 3}H{sub 6}, C{sub 3}H{sub 8}, C{sub 3}H{sub 4} (propyne), H{sub 2}O, SO{sub 2} {plus minus} iso-C{sub 4}H{sub 10} {plus minus} C{sub 4}H{sub 8} (1-butene) {plus minus} CH{sub 3}SH, C{sub 4}H{sub 8} (iso-butylene), ( ) C{sub 4}H{sub 6} (1,3 butadiene), and {plus minus} n-C{sub 4}H{sub 10} {plus minus}C{sub 4}H{sub 8} (trans-2-butene). H{sub 2}O is analyzed directly. O{sub 2} can be analyzed cryogenically between N{sub 2} and Ar, but has not been detected in natural samples to date in this study. Initial inclusion volatile analyses of fluids of interpreted magmatic origin from the Cretaceous Boss Mtn. monzogranite stock-related MoS{sub 2} deposit, central British Columbia of 97 mol% H{sub 2}O, 3% CO{sub 2}, 140-150 ppm N{sub 2}, and 16-39 ppm CH{sub 4} are reasonable in comparison with high temperature volcanic gas analyses from four, active calc-alkaline volcanoes, e.g., the H{sub 2}O contents of volcanic gases from the White Island (New Zealand), Mount St. Helens (Washington, USA), Merapi (Bali, Indonesia), and Momotombo (Nicaragua) volcanoes are 88-95%, > 90%, 88-95% and 93%, respectively; CO{sub 2} contents are 3-10%, 1-10%, 3-8%, and 3.5%. It appears that low, but significant concentrations of alkanes, alkenes, and alkynes have been detected in magmatically derived fluids.

  8. Enthalpy of formation of anisole: implications for the controversy on the O-H bond dissociation enthalpy in phenol.

    PubMed

    Simões, Ricardo G; Agapito, Filipe; Diogo, Hermínio P; da Piedade, Manuel E Minas

    2014-11-20

    Significant discrepancies in the literature data for the enthalpy of formation of gaseous anisole, ΔfHmo(PhOCH3, g), have fueled an ongoing controversy regarding the most reliable enthalpy of formation of the phenoxy radical and of the gas phase O-H bond dissociation enthalpy, DHo(PhO-H), in phenol. In the present work ΔfHmo(PhOCH3, g) was reassessed using a combination of calorimetric determinations and high-level (W2-F12) ab initio calculations. Static-bomb combustion calorimetry led to the standard molar enthalpy of formation of liquid anisole at 298.15 K, ΔfHmo(PhOCH3, l) = −(117.1 ± 1.4) kJ·mol(-1). The corresponding enthalpy of vaporization was obtained as, ΔvapHmo(PhOCH3) = 46.41 ± 0.26 kJ·mol(-1), by Calvet-drop microcalorimetry. These results give ΔfHmo(PhOCH3, g) = −(70.7 ± 1.4) kJ·mol(-1), in excellent agreement with ΔfHmo(PhOCH3, g) = −(70.8 ± 3.2) kJ·mol(-1), obtained from the W2-F12 calculations. The ΔfHmo(PhOCH3, g) here recommended leads to ΔfHmo(PhO•, g) = 55.5 ± 2.4 kJ·mol(-)1 and DH°(PhO-H) = 368.1 ± 2.6 kJ·mol(-1).

  9. Structural basis for piRNA 2'-O-methylated 3'-end recognition by Piwi PAZ (Piwi/Argonaute/Zwille) domains.

    PubMed

    Tian, Yuan; Simanshu, Dhirendra K; Ma, Jin-Biao; Patel, Dinshaw J

    2011-01-18

    Argonaute and Piwi proteins are key players in the RNA silencing pathway, with the former interacting with micro-RNAs (miRNAs) and siRNAs, whereas the latter targets piwi-interacting RNAs (piRNAs) that are 2'-O-methylated (2(')-OCH(3)) at their 3' ends. Germline-specific piRNAs and Piwi proteins play a critical role in genome defense against transposable elements, thereby protecting the genome against transposon-induced defects in gametogenesis and fertility. Humans contain four Piwi family proteins designated Hiwi1, Hiwi2, Hiwi3, and Hili. We report on the structures of Hili-PAZ (Piwi/Argonaute/Zwille) domain in the free state and Hiwi1 PAZ domain bound to self-complementary 14-mer RNAs (12-bp + 2-nt overhang) containing 2(')-OCH(3) and 2'-OH at their 3' ends. These structures explain the molecular basis underlying accommodation of the 2(')-OCH(3) group within a preformed Hiwi1 PAZ domain binding pocket, whose hydrophobic characteristics account for the preferential binding of 2(')-OCH(3) over 2'-OH 3' ends. These results contrast with the more restricted binding pocket for the human Ago1 PAZ domain, which exhibits a reverse order, with preferential binding of 2'-OH over 2(')-OCH(3) 3' ends.

  10. Hydroxyl end groups influence in vibrational and transport properties in polymer/monomer solutions: the PEO/EG case

    NASA Astrophysics Data System (ADS)

    Crupi, V.; Faraone, A.; Majolino, D.; Migliardo, P.; Venuti, V.; Villari, V.

    A study has been made of vibrational properties in ethylene glycol (EG; H(OCH2CH2)OH) and EG monomethyl ether (EGmE; CH3(OCH2CH2)OH) in solution together with poly(ethylene oxide) (PEO; H(OCH2CH2)nOH) at different concentrations, performed by Fourier transform infrared absorbance (FT-IR) spectroscopy. The results ae compared with previous viscometry and photon correlation spectroscopy (PCS) studies, using EG dimethyl ether (EGdE; CH3(OCH2CH2)OCH3) as solvent as well. These homologous systems differ from each other in the number of OH end groups, in particular two for EG, one for EgmE and zero for EGdE. Combining analysis of the vibrational and transport properties of EG, EGmE and EGdE in solution with PEO over a wide range of concentration made it possible to check the quality (good theta or poor) of these three different solvents and the role played by the hydrogen bond in the various solute-solvent interaction mechanisms, resulting in the well known de Gennes scaling law.

  11. Site-selective electroless metallization on porous organosilica films by multisurface modification of alkyl monolayer and vacuum plasma.

    PubMed

    Chen, Giin-Shan; Chen, Sung-Te; Chen, Yenying W; Hsu, Yen-Che

    2013-01-15

    Taking plasma-enhanced chemical vapor deposited porous SiOCH (p-SiOCH) and octadecyltrichlorosilane (OTS) as model cases, this study elucidates the chemical reaction pathways for alkyl-based self-assembled monolayers (SAMs) on porous carbon-doped organosilica films under N(2)-H(2) vacuum plasma illumination. In contrast to previous findings that carboxylic groups are found in alkyl-based SAMs only by exposure to oxygen-based plasma, this study discovers that, upon exposure to reductive nitrogen-based vacuum plasma, surface carboxylic functional groups can be instantly formed on OTS-coated p-SiOCH films. Particular attention is given to developing a multisurface modification process, starting with the modification of p-SiOCH films by N(2)-H(2) plasma and continuing with SAM deposition and plasma patterning; this ultimately leads to site-selective seeding for the spatially controlled fabrication of Cu-wire metallization by electroless deposition. Plasma diagnosis and X-ray near-edge absorption and Fourier transform infrared spectroscopies show that, by adequately controlling the plasma parameters, the bulk of the p-SiOCH films are free from plasma damage (in terms of degradation in bonding structures and electrical properties); the formation of the seed-trapping carboxylic functional groups on the surface, the key factor for the validity of this new seeding process, is due to a water-mediated chemical oxygenation route.

  12. Analysis of Wartime Consumption Rates for Chemical Defensive Equipment. Volume 3. Appendix D. Post-Processor Data

    DTIC Science & Technology

    1986-05-01

    101.18 113.96 123.0 -N-----5 CTIC CATA - 10 RMXL FO]R WVCl&A KR DAYS 1 DRDI 15 Mv% tM OF O-eiICA&L RT•M••M 25 MIL DAS FJIF FOER EKH ODY OF BATTLE OaNm 1...0.68 0.68 6.66s 0.08 0.6 AG 0.68 .0.6 0.68 6.68 0.68e 66 0. 68 0. 68 ~e 0.0 AVEVM NM. RMAIE PER DAY PER 160M ~ TM AfW I CaMrWi 1 2 3 4 5 6 7 8 MCG 2...I6 IN W3’PPLM2 FR’ T - TMS CJ1Rw 1 2 3 4 5 6 7 8 TOTAL 1 0.95 3.42 2.14 0.19 3.05 5.02 4.25 0.60 19.1 2 4.37 3.29 5.57 2.22 3.93 0.0 6.60 3.94 23.1 3

  13. Study of the OH and Cl-initiated oxidation, IR absorption cross-section, radiative forcing, and global warming potential of four C4-hydrofluoroethers.

    PubMed

    Oyaro, Nathan; Sellevåg, Stig R; Nielsen, Claus J

    2004-11-01

    Infrared absorption cross-sections and OH and Cl reaction rate coefficients for four C4-hydrofluoroethers (CF3)2CHOCH3, CF3CH2OCH2CF3, CF3CF2CH2OCH3, and CHF2CF2CH2OCH3 are reported. Relative rate measurements at 298 K and 1013 hPa of OH and Cl reaction rate coefficients give k(OH+(CF3)2CHOCH3) = (1.27+/-0.13) x 10(-13), k(OH+CF3CH2OCH2CF3) = (1.51+/-0.24) x 10(-13), k(OH+CF3CF2CH2OCH3) = (6.42+/-0.33) x 10(-13), k(OH+CHF2CF2CH2OCH3) = (8.7 +/-0.5) x 10(-13), k(Cl+(CF3)2CHOCH3) = (8.4+/-1.3) x 10(-12), k(Cl+CF3CH2OCH2CF3) = (6.5+/-1.7) x 10(-13), k(Cl+CF3CF2CH2OCH3) = (4.0+/-0.8) x 10(-11), and k(Cl+CHF2CF2CH2OCH3) = (2.65+/-0.17) x 10(-11) cm3 molecule(-1) s(-1). The primary products of the OH and Cl reactions with the fluorinated ethers have been identified as esters, and OH and Cl reaction rate coefficients for one of these, CF3CH2OCHO, are reported: k(OH+CF3CH2OCHO) = (7.7+/-0.9) x 10(-14) and kCl+CF3CH2OCHO) = (6.3+/-1.9) x 10(-14) cm3 molecule(-1) s(-1) The rate coefficient for the Cl-atom reaction with CHF2CH2F is derived as k(Cl+CHF2CH2F) = (3.0+/-0.9) x 10(-14) cm3 molecule(-1) s(-1) at 298 K. The error limits include 3sigma from the statistical data analyses as well as the errors in the rate coefficients of the reference compounds employed. The tropospheric lifetimes of the hydrofluoroethers are estimated to be short tauOH((CF3)2CHOCH3) approximately 100 days, tauOH(CF3CH2OCH2CF3) approximately 80 days, tauOH(CF3CF2CH2OCH3) approximately 20 days, and tauOH(CHF2CF2CH2OCH3) approximately 14 days, and their global warming potentials are small compared to CFC-11.

  14. Theoretical studies on atmospheric chemistry of HFE-245mc and perfluoro-ethyl formate: Reaction with OH radicals, atmospheric fate of alkoxy radical and global warming potential

    NASA Astrophysics Data System (ADS)

    Lily, Makroni; Baidya, Bidisha; Chandra, Asit K.

    2017-02-01

    Theoretical studies have been performed on the kinetics, mechanism and thermochemistry of the hydrogen abstraction reactions of CF3CF2OCH3 (HFE-245mc) and CF3CF2OCHO with OH radical using DFT based M06-2X method. IRC calculation shows that both hydrogen abstraction reactions proceed via weakly bound hydrogen-bonded complex preceding to the formation of transition state. The rate coefficients calculated by canonical transition state theory along with Eckart's tunnelling correction at 298 K: k1(CF3CF2OCH3 + OH) = 1.09 × 10-14 and k2(CF3CF2OCHO + OH) = 1.03 × 10-14 cm3 molecule-1 s-1 are in very good agreement with the experimental values. The atmospheric implications of CF3CF2OCH3 and CF3CF2OCHO are also discussed.

  15. Tolerance of β-diketone hydrolases as representatives of the crotonase superfamily towards organic solvents.

    PubMed

    Siirola, Elina; Grischek, Barbara; Clay, Dorina; Frank, Annika; Grogan, Gideon; Kroutil, Wolfgang

    2011-12-01

    Crotonase superfamily enzymes catalyze a wide variety of reactions, including hydrolytic C-C bond cleavage in symmetrical β-diketones by 6-oxo camphor hydrolase (OCH) from Rhodococcus sp. The organic solvent tolerance and temperature stability of OCH and its structurally related ortholog Anabaena β-diketone hydrolase have been investigated. Both enzymes showed excellent tolerance toward organic solvents; for instance, even in the presence of 80% (v/v) THF or dioxane, OCH was still active. In most solvent mixtures, except methanol, the stereospecificity was conserved (>99% e.e. of product), hence neither the type of solvent nor its concentration appeared to have an effect on the stereoselectivity of the enzyme. Attempts to correlate the observed activities with log P, functional solvent group or denaturing capacity (DC) of the solvent were only successful in the case of DC for water miscible solvents. This study represents the first investigation of organic solvent stability for members of the crotonase superfamily.

  16. Tetrahydroberberine, a pharmacologically active naturally occurring alkaloid.

    PubMed

    Pingali, Subramanya; Donahue, James P; Payton-Stewart, Florastina

    2015-04-01

    Tetrahydroberberine (systematic name: 9,10-dimethoxy-5,8,13,13a-tetrahydro-6H-benzo[g][1,3]benzodioxolo[5,6-a]quinolizine), C20H21NO4, a widely distributed naturally occurring alkaloid, has been crystallized as a racemic mixture about an inversion center. A bent conformation of the molecule is observed, with an angle of 24.72 (5)° between the arene rings at the two ends of the reduced quinolizinium core. The intermolecular hydrogen bonds that play an apparent role in crystal packing are 1,3-benzodioxole -CH2···OCH3 and -OCH3···OCH3 interactions between neighboring molecules.

  17. Spectroscopic characterization of the complex between water and the simplest Criegee intermediate CH2OO.

    PubMed

    Nakajima, Masakazu; Endo, Yasuki

    2014-04-07

    The hydrogen-bonded complex between water and the simplest Criegee intermediate CH2OO was detected by Fourier-transform microwave spectroscopy under a jet-cooled condition. Both a-type and b-type rotational transitions were observed for H2O-CH2OO and D2O-CH2OO. The determined rotational constants enable us to conclude that the complex has an almost planar ring structure with the terminal oxygen atom of CH2OO being a strong proton acceptor.

  18. Spectroscopic characterization of the complex between water and the simplest Criegee intermediate CH2OO

    NASA Astrophysics Data System (ADS)

    Nakajima, Masakazu; Endo, Yasuki

    2014-04-01

    The hydrogen-bonded complex between water and the simplest Criegee intermediate CH2OO was detected by Fourier-transform microwave spectroscopy under a jet-cooled condition. Both a-type and b-type rotational transitions were observed for H2O-CH2OO and D2O-CH2OO. The determined rotational constants enable us to conclude that the complex has an almost planar ring structure with the terminal oxygen atom of CH2OO being a strong proton acceptor.

  19. A rare tetranuclear thorium(IV) μ4 -oxo cluster and dinuclear thorium(IV) complex assembled by carbon-oxygen bond activation of 1,2-dimethoxyethane (DME).

    PubMed

    Travia, Nicholas E; Scott, Brian L; Kiplinger, Jaqueline L

    2014-12-15

    The synthesis and X-ray crystal structure of two new multinuclear thorium complexes are reported. The tetranuclear μ4 -oxo cluster complex Th4 (μ4 -O)(μ-Cl)2 I6 [κ(2) (O,O')-μ-O(CH2 )2 OCH3 ]6 and the dinuclear complex Th2 I5 [κ(2) (O,O')-μ-O(CH2 )2 OCH3 ]3 (DME) (DME=dimethoxyethane) are formed by CO bond activation of 1,2-dimethoxyethane (DME) mediated by thorium iodide complexes.

  20. Organic pollutant burden of the giant mussels Choromytilus chorus from the south-central Chilean coast.

    PubMed

    Toro, Beatriz; Palma-Fleming, Hernán; Navarro, Jorge M

    2004-04-01

    A comparative quantitative analysis was made on the contents of organochlorines (OCh) and polycyclic aromatic hydrocarbons (PAH) in tissues of the giant mussel Choromytilus chorus from three bays in south-central Chile exposed to various degrees of pollutant input. Mussels from the three bays contained levels of OCh near the detection limits of method, with a tendency to be slightly higher in the polluted bay (San Vicente) than in the other bays (Corral and Yaldad). PAH levels and types in Corral and Yaldad were well below of carcinogenicity permitted in mussels for human consumption.

  1. Synthesis, Characterization, and Modification of Poly(Organophosphazenes), that Bear Both 2,2,2-Trifluoroethoxy and Phenoxy Groups

    DTIC Science & Technology

    1993-05-18

    tissues to the surfaces of these various polymers . Results and Discussion Synthesis and Composition of Polymers . (a) Competitive Reactions of Sodium...attached MAY 2 6 1993U •i• ’ 2 6293-11554 14. SUBJECT TE’RMS’ 1. NUMBER OF PAGES Polymers , phosphazenes, synthesis , elastomers 45 16. PRICE CODE 17...of NP(OCH2CF 3)2 , NP(OCH 2CF3 )(OPh) and NP(OPh)2 units in the polymer are dependent on both the synthesis method and the amounts of CF3CH20- Na+ and

  2. Nitroaliphatic difluoroformals

    DOEpatents

    Peters, Howard M.; Simon, Jr., Robert L.

    1978-01-01

    Nitroaliphatic difluoroformals of the formula RCH.sub.2 OCF.sub.2 OCH.sub.2 R' wherein R = FC(NO.sub.2).sub.2 -- and R' = F.sub.2 C(NO.sub.2)-- or CF.sub.3 --; or R = R' = CF.sub.3 OCH.sub.2 C(NO.sub.2).sub.2 --. The compounds are prepared in accordance with the following reaction: ##STR1## carried out at temperatures of from about 95.degree. C to about 150.degree. C. The compounds are especially useful as energetic plasticizers in explosive compositions.

  3. Analysis of torsional spectra of molecules with two internal C3v rotors. II - Far infrared and low frequency Raman spectra of dimethylether isotopes

    NASA Technical Reports Server (NTRS)

    Groner, P.; Durig, J. R.

    1977-01-01

    The torsional far infrared and Raman spectra of gaseous CH3OCH3, CD3OCH3, and CD3OCD3 are presented. They are analyzed using a computer program which is based on the results of an extensive investigation of the isometric groups and of the symmetry groups of the rotation-internal rotation Hamiltonians of a series of semirigid two-top models. Four or more Fourier coefficients of the potential functions in two variables could be determined for each isotope. Strong evidence was found for Fermi-resonance-type interactions with the COC bending mode.

  4. Stabile Radikalanionen von Aromaten: Strahlenchemische Erzeugung in Gegenwart von Natrium-dihydridobis( 2-methoxyethoxy) aluminat

    NASA Astrophysics Data System (ADS)

    Getoff, Nikola; Haenel, Matthias W.; Hildenbrand, Knut; Richter, Udo-Burckhard; Solar, Sonja

    1990-02-01

    Arenes are reduced at room temperature to their very long-lived radical anions by exposing the solution of the arene and NaAlH2(OCH2CH2OCH3 )2 (1) in dimethoxyethane (DME) to an ionizing radiation (electrons, gamma- or X-rays) for few minutes: Thereby 1 is acting as a scavenger for the solvent counter ions which are produced concomitantly to solvated electrons by the radiolysis. The method is very convenient for the ESR and UV-VIS spectroscopy of aromatic radical anions.

  5. A Scientist or Salesman? Identity Construction through Referent Honorifics on a Japanese Shopping Channel Program

    ERIC Educational Resources Information Center

    Cook, Haruko Minegishi

    2013-01-01

    This paper explores how referent honorifics contribute to identity construction on a Japanese TV shopping channel program. Drawing on Ochs' twostep model of indexicality (1993, 1996) and Agah's proposal (1993) that honorifics are not directly linked to social status but index a "relative position within events of discursive interaction"…

  6. Synthesis, antityrosinase activity of curcumin analogues, and crystal structure of (1 E,4 E)-1,5-bis(4-ethoxyphenyl)penta-1,4-dien-3-one

    NASA Astrophysics Data System (ADS)

    Chantrapromma, S.; Ruanwas, P.; Boonnak, N.; Chantrapromma, K.; Fun, H.-K.

    2016-12-01

    Five derivatives of curcumin analogue ( R = OCH2CH3 ( 1), R = N(CH3)2 ( 2), R = 2,4,5-OCH3 ( 3), R = 2,4,6-OCH3 ( 4), and R = 3,4,5-OCH3 ( 5)) were synthesized and characterized by 1H NMR, FT-IR and UV-Vis spectroscopy. The synthesized derivatives were screened for antityrosinase activity, and found that 4 and 5 possess such activity. The crystal structure of 1 was determined by single crystal X-ray diffraction: monoclinic, sp. gr. P21/ c, a = 17.5728(15) Å, b = 5.9121(5) Å, c = 19.8269(13) Å, β = 121.155(5)°, Z = 4. The molecule 1 is twisted with the dihedral angle between two phenyl rings being 15.68(10)°. In the crystal packing, the molecules 1 are linked into chains by C-H···π interactions and further stacked by π···π interactions with the centroid-centroid distance of 3.9311(13) Å.

  7. Thermodynamic Properties of Carbosilane Dendrimers of the Sixth Generation with Ethylene Oxide Terminal Groups.

    PubMed

    Sologubov, Semen S; Markin, Alexey V; Smirnova, Natalia N; Novozhilova, Natalia A; Tatarinova, Elena A; Muzafarov, Aziz M

    2015-11-12

    The temperature dependences of heat capacities of carbosilane dendrimers of the sixth generation with ethyleneoxide terminal groups, denoted as G6[(OCH2CH2)1OCH3]256 and G6[(OCH2CH2)3OCH3]256, were measured in the temperature range from T = (6 to 520) K by precision adiabatic calorimetry and differential scanning calorimetry (DSC). In the above temperature range the physical transformations, such as glass transition and high-temperature relaxation transition, were detected. The standard thermodynamic characteristics of the revealed transformations were determined and analyzed. The standard thermodynamic functions, namely, heat capacity Cp°(T), enthalpy H°(T) - H°(0), entropy S°(T) - S°(0), and Gibbs energy G°(T) - H°(0) for the range from T → 0 to 520 K, and the standard entropies of formation ΔfS° of the investigated dendrimers in the devitrified state at T = 298.15 K, were calculated per corresponding moles of the notional structural units. The standard thermodynamic properties of dendrimers under study were discussed and compared with literature data for carbosilane dendrimers with different functional terminal groups.

  8. The Brief Child and Family Phone Interview (BCFPI): 1. Rationale, Development, and Description of a Computerized Children's Mental Health Intake and Outcome Assessment Tool

    ERIC Educational Resources Information Center

    Cunningham, Charles E.; Boyle, Michael H.; Hong, Sunjin; Pettingill, Peter; Bohaychuk, Donna

    2009-01-01

    Background: This study describes the development of the Brief Child and Family Phone Interview (BCFPI)--a computer-assisted telephone interview which adapts the revised Ontario Child Health Study's (OCHS-R) parent, teacher, and youth self-report scales for administration as intake screening and treatment outcome measures in children's mental…

  9. Peer Socialization into Gendered L2 Mandarin Practices in a Study Abroad Context: Talk in the Dorm

    ERIC Educational Resources Information Center

    Diao, Wenhao

    2016-01-01

    This article reports on the peer socialization of gendered Mandarin practices between three American students and their Chinese roommates in a college dorm in China. Gender is often perceived to be a salient identity category among adult L2 learners overseas. Drawing on the language socialization framework (Ochs and Schieffelin 1984), this study…

  10. Polymerizable 2(2-hydroxynaphthyl)2H-benzotriazole compounds

    DOEpatents

    Gomez, Peter M.; Neidlinger, Hermann H.

    1991-01-01

    Benzotriazole compounds having the formula: ##STR1## wherein R.sub.1 is H, Cl, or OCH.sub.3 ; R.sub.2 is a hydroxynaphthyl group; and R.sub.3 is a vinyl unsaturated polymerizable group. Homopolymers or copolymers thereof are effective as UV light stabilizers and absorbers.

  11. Polymerizable 2(2-hydroxynaphthyl)2H-benzotriazole compounds

    DOEpatents

    Gomez, P.M.; Neidlinger, H.H.

    1991-07-16

    Benzotriazole compounds having the formula: ##STR1## wherein R.sub.1 is H, Cl, or OCH.sub.3 ; R.sub.2 is a hydroxynaphthyl group; and R.sub.3 is a vinyl unsaturated polymerizable group. Homopolymers or copolymers thereof are effective as UV light stabilizers and absorbers.

  12. Adolescent Tobacco and Cannabis Use: Young Adult Outcomes from the Ontario Child Health Study

    ERIC Educational Resources Information Center

    Georgiades, Katholiki; Boyle, Michael H.

    2007-01-01

    Background: This study examines the longitudinal associations between adolescent tobacco and cannabis use and young adult functioning. Methods: Data for analysis come from the Ontario Child Health Study (OCHS), a prospective study of child health, psychiatric disorder and adolescent substance use in a general population sample that began in 1983,…

  13. A Voyage through the Radio Universe

    ERIC Educational Resources Information Center

    Spuck, Timothy

    2004-01-01

    Each year, professionals and amateurs alike make significant contributions to the field of astronomy. High school students can also conduct astronomy research. Since 1992, the Radio Astronomy Research Team from Oil City Area Senior High School (OCHS) in Oil City, Pennsylvania, has traveled each year to the National Radio Astronomy Observatory…

  14. Debate on the Draft--Helping Students Decide Where They Stand.

    ERIC Educational Resources Information Center

    Victory, James

    1981-01-01

    Presents four exercises to help secondary school social studies students understand the complex issues of the draft. Students participate in a mock draft lottery, analyze Phil Och's Draft Dodger Rag, examine how individual experiences affect attitudes, and compare writings by Bill Mauldin and Ron Kovic. (KC)

  15. Socialising ESL Students into the Discourse of School Science through Academic Writing

    ERIC Educational Resources Information Center

    Huang, Jingzi

    2004-01-01

    This paper takes the view of "language socialization" (Schieffelin & Ochs, 1986) to examine, through a case study of a secondary ESL science class, the instructional process that aims at facilitating the integration of specific science content learning and the construction of a particular kind of written discourse typically found in school…

  16. The Spoken Self: An Ethnographic Exploration of Accent and Identity

    ERIC Educational Resources Information Center

    Rehn, Stefanie

    2010-01-01

    This study examines the relationship between accent and identity in three Chinese graduate students attending a large research-one university in the northeastern United States. The study is based on Och's (1993) concept if identity as jointly constructed by the individual herself and the persons and conventions of her culture. It also examines the…

  17. Social Networking in an Intensive English Program Classroom: A Language Socialization Perspective

    ERIC Educational Resources Information Center

    Reinhardt, Jonathon; Zander, Victoria

    2011-01-01

    This ongoing project seeks to investigate the impact, inside and outside of class, of instruction focused on developing learner awareness of social-networking site (SNS) use in an American Intensive English Program (IEP). With language socialization as an interpretative framework (Duff, in press; Ochs, 1988; Watson-Gegeo, 2004), the project uses a…

  18. Schools Reaching Out: An Introduction.

    ERIC Educational Resources Information Center

    Heleen, Owen

    1990-01-01

    Introduces an issue devoted to the Schools Reaching Out projects at David A. Ellis School in Roxbury (MA) and Adolph S. Ochs School in New York City. Projects attempt to link the schools with parents and their communities to promote the students' academic and social success. (DM)

  19. Legitimate Peripheral Participation and Language Learning: Two Quichua Learners in a Transnational Community

    ERIC Educational Resources Information Center

    Back, Michele

    2011-01-01

    Using data from a multisited ethnography of Ecuadorian transnational musicians, I applied Lave and Wenger's (1991) concept of legitimate peripheral participation and Jacoby and Ochs's (1995) notion of co-construction to examine two musicians' attempts to learn Quichua, an Ecuadorian indigenous language. Through an analysis aided by constructivist…

  20. Is the σ(600) a glueball? Two photon reactions can tell us

    NASA Astrophysics Data System (ADS)

    Pennington, M. R.

    2001-08-01

    Minkowski and Ochs have recently argued that the small two photon coupling of a conjectured σ(600) is so small that it is likely to be a glueball. We ask whether this can be so or whether it is simply gauge invariance that produces the observed low mass suppression?

  1. 40 CFR Table 2 to Subpart Jj of... - List of Volatile Hazardous Air Pollutants

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... (Aroclors) 1336363 Polycyclic Organic Matter b 1,3-Propane sultone 1120714 beta-Propiolactone 57578... glycol ethers with the structure: R-(OCH2CH2)n—OH. Polymers are excluded from the glycol category. b Includes organic compounds with more than one benzene ring, and which have a boiling point greater than...

  2. Electron impact cross sections for surrogates of DNA sugar phosphate backbone

    NASA Astrophysics Data System (ADS)

    Bhowmik, Pooja; Joshipura, K. N.; Pandya, Siddharth

    2012-11-01

    Ionization and elastic cross sections by electron impact on H3PO4 and OP(OCH3)3 which are substitutes for the components of DNA phosphate group. We have employed the Complex Scattering Potential-ionization contribution (CSP-ic) formalism to calculate the cross sections in the energy range from ionization threshold to 2000 eV.

  3. Role of Protein Glycosylation in Candida parapsilosis Cell Wall Integrity and Host Interaction

    PubMed Central

    Pérez-García, Luis A.; Csonka, Katalin; Flores-Carreón, Arturo; Estrada-Mata, Eine; Mellado-Mojica, Erika; Németh, Tibor; López-Ramírez, Luz A.; Toth, Renata; López, Mercedes G.; Vizler, Csaba; Marton, Annamaria; Tóth, Adél; Nosanchuk, Joshua D.; Gácser, Attila; Mora-Montes, Héctor M.

    2016-01-01

    Candida parapsilosis is an important, emerging opportunistic fungal pathogen. Highly mannosylated fungal cell wall proteins are initial contact points with host immune systems. In Candida albicans, Och1 is a Golgi α1,6-mannosyltransferase that plays a key role in the elaboration of the N-linked mannan outer chain. Here, we disrupted C. parapsilosis OCH1 to gain insights into the contribution of N-linked mannosylation to cell fitness and to interactions with immune cells. Loss of Och1 in C. parapsilosis resulted in cellular aggregation, failure of morphogenesis, enhanced susceptibility to cell wall perturbing agents and defects in wall composition. We removed the cell wall O-linked mannans by β-elimination, and assessed the relevance of mannans during interaction with human monocytes. Results indicated that O-linked mannans are important for IL-1β stimulation in a dectin-1 and TLR4-dependent pathway; whereas both, N- and O-linked mannans are equally important ligands for TNFα and IL-6 stimulation, but neither is involved in IL-10 production. Furthermore, mice infected with C. parapsilosis och1Δ null mutant cells had significantly lower fungal burdens compared to wild-type (WT)-challenged counterparts. Therefore, our data are the first to demonstrate that C. parapsilosis N- and O-linked mannans have different roles in host interactions than those reported for C. albicans. PMID:27014229

  4. Co-Construction in Korean Interaction

    ERIC Educational Resources Information Center

    Ju, Hee

    2011-01-01

    This dissertation explores co-construction of a situated activity in a current unit by mainly focusing on hearers' actions. The "co-construction" involves a process of interaction in which speakers and hearers jointly construct the form and the meaning of ongoing utterances even when they disagree with each other (Jacoby & Ochs,…

  5. 1,2-Diphenylethylamines as potential non-stimulant anorectics.

    PubMed

    Ghosh, P; Bolt, A G; Mrongovius, R I

    1978-01-01

    A series of 1,2-diphenylethylamines has been synthesized in which the phenyl rings were substituted with Cl, OCH3 or CF3 at various positions and in various combinations. Four N-ethylpiperazino and N-ethylmorpholino compounds were also prepared. When tested in rats, some of the compounds were found to be potent anorectics and none of them stimulated motor activity.

  6. Escalation of Agitative Rhetoric: A Case Study of Mattachine Midwest, 1967-1970.

    ERIC Educational Resources Information Center

    Darsey, James

    This paper examines the adequacy of Bowers and Ochs' theory of social movements as applied to the escalating agitative strategies of a dissident group, the homosexual-rights organization Mattachine Midwest. The group's activities are described chronologically, in terms of the strategies employed: petition, promulgation, polarization,…

  7. Deciphering the Molecular Mechanisms of Breast Cancer

    DTIC Science & Technology

    2005-03-01

    suppressor genes in mitotic and meiotic Epstein, J.A., Yen, T.J., and Shiekhattar, R. (2001). A human BRCA2 complex containing a structural DNA... meiotic cells. Cell 88, 265–275. 96, 11364–11369. Scully, R., Chen, J., Ochs, R.L., Keegan, K., Hoehstra, M., Feunteun, J., and Livingston, D.M. (1997c

  8. Parental Expectations of the Swedish Municipal School of Arts

    ERIC Educational Resources Information Center

    Lilliedahl, Jonathan; Georgii-Hemming, Eva

    2009-01-01

    This article draws on a study designed to analyse parental expectations of the Swedish municipal school of arts (hereafter MSA) (in Swedish: kommunal musik- och kulturskola). The study is based on in-depth interviews conducted and informed by grounded theory. Although parental expectations are scarcely uniform, the study reveals a hope that the…

  9. New aromatase inhibitors. Synthesis and biological activity of pyridyl-substituted tetralone derivatives.

    PubMed

    Bayer, H; Batzl, C; Hartmann, R W; Mannschreck, A

    1991-09-01

    The (E)-2-(4-pyridylmethylene)-1-tetralones 1-7 (1, H; 2, 5-OCH3; 3, 6-OCH3; 4, 7-OCH3; 5, 5-OH; 6, 6-OH; 7, 7-OH) were obtained by aldol condensation of the corresponding 1-tetralones with 4-pyridinecarboxaldehyde, and in the case of the OH compounds 5 and 7 subsequent ether cleavage of the OCH3-substituted 2-(4-pyridylmethylene)-1-tetralones. Catalytic hydrogenation of 1-4 gave the 2-(4-pyridylmethyl)-1-tetralones 8-11 (8, H; 9, 5-OCH3; 10, 6-OCH3; 11, 7-OCH3). Subsequent ether cleavage of 9-11 led to the corresponding OH compounds 12-14 (12, 5-OH; 13, 6-OH; 14, 7-OH). The enantiomers of 11 and 12 were separated semipreparatively by HPLC on triacetylcellulose. All compounds (1-14) showed an inhibition of human placental aromatase exhibiting relative potencies from 2.2 to 213 [compounds 6 and (+)-12, respectively; aromatase inhibitory potency of aminoglutethimide (AG) = 1]. The compounds exhibited no or only a weak inhibition of desmolase [cholesterol side chain cleavage enzyme; maximum activity shown by 12, 23% inhibition (25 microM); AG, 53% inhibition (25 microM)]. In vivo, however, the compounds were not superior to AG as far as the reduction of the plasma estradiol concentration and the mammary carcinoma (MC) inhibiting properties are concerned (PMSG-primed SD rats as well as DMBA-induced MC of the SD rat, pre- and postmenopausal experiments, and the transplantable MXT-MC of the BD2F1 mouse). This is due to a fast decrease of the plasma E2 concentration inhibiting effect as could be shown by a kinetic experiment. In addition, select compounds inhibited rat ovarian aromatase much less than human placental aromatase (12, factor of 10). Estrogenic effects as a cause for the poor in vivo activity of the test compounds could be excluded, since they did not show affinity for the estrogen receptor.

  10. Involvement of T-cell immunoregulation by ochnaflavone in therapeutic effect on fungal arthritis due to Candida albicans.

    PubMed

    Lee, Jue-Hee

    2011-07-01

    Arthritis due to pathogenic fungi is a serious disease causing rapid destruction of the joint. In the pathogenesis of arthritis, T lymphocytes are considered to be one of the major immune cells. In present study, we examined the T cell immunoregulatory effect by ochnaflavone (Och), a biflavonoid, on arthritis caused by Candida albicans that is the most commonly associated with fungal arthritis. To examine the effects of ochnaflavonon Candida albicans-caused septic arthritis, an emulsified mixture of C. albicans cell wall and complete Freund's adjuvant (CACW/CFA) was injected into BALB/c mice via hind footpad route on days -3, -2, and -1. On Day 0, Och at 1 or 2 mg/dose/time was intratraperitoneally given to mice with the swollen footpad every other day for 3 times. The footpad-edema was measured for 20 days. Results revealed that Och reduced the edema at all dose levels and furthermore, there was app. 45% reduction of the edema in animals given 2 mg-dose at the peak of septic arthritis (p < 0.05). This anti-arthritic effect was accompanied by the diminishing of the DTH (delayed type hypersensitivity) activity against the CACW and by the provoking of the dominant T helper 2 (Th2) type cytokines production (IL-4 and Il-10), which appeared to result in a suppression of T helper 1 cytokines (IFN-γ and IL-2). Besides the T cell immunoregulatory activity, Och inhibited T cells activation as evidenced by the IL-2 reduction from PMA/ionomycin-stimulated Jurkat cell line and in addition, the compound killed macrophages in a dose-dependent manner (p < 0.05). However, Och caused no hemolysis (p < 0.05). These data implicate that Och, which has anti-arthritic activity based on the Th2 dominance as well as macrophage removal, can be safely administered into the blood circulation for treatment of the arthritis caused by C. albicans. Thus, it can be concluded that Och would be an ideal immunologically evaluated agent for treating of Candida arthritis.

  11. Cyclo- and carbophosphazene-supported ligands for the assembly of heterometallic (Cu2+/Ca2+, Cu2+/Dy3+, Cu2+/Tb3+) complexes: synthesis, structure, and magnetism.

    PubMed

    Chandrasekhar, Vadapalli; Senapati, Tapas; Dey, Atanu; Das, Sourav; Kalisz, Marguerite; Clérac, Rodolphe

    2012-02-20

    The carbophosphazene and cyclophosphazene hydrazides, [{NC(N(CH(3))(2))}(2){NP{N(CH(3))NH(2)}(2)}] (1) and [N(3)P(3)(O(2)C(12)H(8))(2){N(CH(3))NH(2)}(2)] were condensed with o-vanillin to afford the multisite coordination ligands [{NC(N(CH(3))(2))}(2){NP{N(CH(3))N═CH-C(6)H(3)-(o-OH)(m-OCH(3))}(2)}] (2) and [{N(2)P(2)(O(2)C(12)H(8))(2)}{NP{N(CH(3))N═CH-C (6)H(3)-(o-OH)(m-OCH(3))}(2)}] (3), respectively. These ligands were used for the preparation of heterometallic complexes [{NC(N(CH(3))(2))}(2){NP{N(CH(3))N═CH-C(6)H(3)-(o-O)(m-OCH(3))}(2)}{CuCa(NO(3))(2)}] (4), [{NC(N(CH(3))(2))}(2){NP{N(CH(3))N═CH-C(6)H(3)-(o-O)(m-OCH(3))}(2)}{Cu(2)Ca(2)(NO(3))(4)}]·4H(2)O (5), [{NC(N(CH(3))(2))}(2){NP{N(CH(3))N═CH-C(6)H(3)-(o-O)(m-OCH(3))}(2)}{CuDy(NO(3))(4)}]·CH(3)COCH(3) (6), [{NP(O(2)C(12)H(8))}(2){NP{N(CH(3))N═CH-C(6)H(3)-(o-O)(m-OCH(3))}(2)}{CuDy(NO(3))(3)}] (7), and [{NP(O(2)C(12)H(8))}(2){NP{N(CH(3))N═CH-C(6)H(3)-(o-O)(m-OCH(3))}(2)}{CuTb(NO(3))(3)}] (8). The molecular structures of these compounds reveals that the ligands 2 and 3 possess dual coordination pockets which are used to specifically bind the transition metal ion and the alkaline earth/lanthanide metal ion; the Cu(2+)/Ca(2+), Cu(2+)/Tb(3+), and Cu(2+)/Dy(3+) pairs in these compounds are brought together by phenoxide and methoxy oxygen atoms. While 4, 6, 7, and 8 are dinuclear complexes, 5 is a tetranuclear complex. Detailed magnetic properties on 6-8 reveal that these compounds show weak couplings between the magnetic centers and magnetic anisotropy. However, the ac susceptibility experiments did not reveal any out of phase signal suggesting that in these compounds slow relaxation of magnetization is absent above 1.8 K.

  12. Environmental risk assessment of hydrofluoroethers (HFEs).

    PubMed

    Tsai, Wen-Tien

    2005-03-17

    Hydrofluoroethers (HFEs) are being used as third generation replacements to chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs) and perfluorocarbons (PFCs) because of their nearly zero stratospheric ozone depletion and relatively low global warming potential. HFEs have been developed under commercial uses as cleaning solvents (incl., HFE-7500, C7F15OC2H5; HFE-7200, C4F9OC2H5; HFE-7100, C4F9CH3; HFE-7000, n-C3F7OCH3), blowing agents (incl., HFE-245mc, CF3CF2OCH3; HFC-356mec, CF3CHFCF2OCH3), refrigerants (incl., HFE-143a, CF3OCH3; HFE-134, CHF2OCHF2; HFE-245mc, CF3CF2OCH3), and dry etching agents in semiconductor manufacturing, (incl., HFE-227me, CF3OCHFCF3). From the environmental, ecological, and health points of view, it is important to understand their environmental risks for these HFEs from a diversity of commercial applications and industrial processes. This paper aims to introduce these HFEs with respect to physiochemical properties, commercial uses, and environmental hazards (i.e. global warming, photochemical potential, fire and explosion hazard, and environmental partition). Further, it addresses the updated data on the human toxicity, occupational exposure and potential health risk of commercial HFEs. It is concluded that there are few HFEs that still possess some environmental hazards, including global warming, flammability hazard and adverse effect of exposure. The partition coefficient for these HFEs has been estimated using the group contribution method; the values of logKow for commercial HFEs have been estimated to be below 3.5.

  13. Comparative photodynamic therapy study using two phthalocyanine derivatives

    PubMed Central

    YSLAS, EDITH INÉS; MILLA, LAURA NATALIA; ROMANINI, SILVIA; DURANTINI, EDGARDO NÉSTOR; BERTUZZI, MABEL; RIVAROLA, VIVIANA ALICIA

    2010-01-01

    In the present study, a comparative photodynamic therapy (PDT) study was performed using the phthalocyanine derivatives, ZnPc(OCH3)4 and ZnPc(CF3)4, in a mouse tumor model, under identical experimental procedures. We studied the ablation of tumors induced by PDT. The end-point was to compare the photodynamic efficacy of ZnPc(OCH3)4 and ZnPc(CF3)4. ZnPc(OCH3)4 and ZnPc(CF3)4 were administered intraperitoneally at a dose of 0.2 mg/kg body weight. The injections of drugs were carried out in Balb/c mice bearing subcutaneously inoculated LM2 mouse mammary adenocarcinoma. Histological examination and serum biochemical parameters were used to evaluate hepatic and renal toxicity and function. Phototherapeutic studies were achieved employing a light intensity of 210 J/cm2. After PDT, tumoral regression analyses were carried out, and the degree of tumor cell death was measured utilizing the vital stain Evan’s blue. In this pilot study, we revealed that the cytotoxic effect of ZnPc(OCH3)4 after PDT led to a higher success rate compared to ZnPc(CF3)4-PDT when both were intraperitoneally injectioned. Both phthalocynanine derivatives were able to induce ablation in the tumors. In summary, these results demonstrate the feasibility of ZnPc(OCH3)4- or ZnPc(CF3)4-PDT and its potential as a treatment for small tumors. PMID:22993594

  14. OCO and NCO chelated derivatives of heavier group 15 elements. Study on possibility of cyclization reaction via intramolecular ether bond cleavage.

    PubMed

    Dostál, Libor; Jambor, Roman; Růžička, Aleš; Jirásko, Robert; Holeček, Jaroslav; De Proft, Frank

    2011-09-21

    A set of four pincer ligands, either the OCO type ligands L(1-3) [2,6-(ROCH(2))(2)C(6)H(3)](-), where R = Me (L(1)), mesityl (L(2)), t-Bu (L(3)) or novel NCO ligand [2-(Me(2)NCH(2))-6-(t-BuOCH(2))C(6)H(3)](-) was studied. The reaction of L(4)Li with PCl(3) resulted in isolation of [2-(OCH(2))-6-(Me(2)NCH(2))C(6)H(3)]PCl (1) as a result of intramolecular ether bond cleavage and elimination of t-BuCl. The conversion between the organolithium compounds L(1,2,4)Li and AsCl(3) led to the desired chlorides, i.e. (L(1))(2)AsCl (2), L(2)AsCl(2) (3), L(4)AsCl(2) (5), but an analogous reaction using the L(3)Li compound gave [2-(OCH(2))-6-(t-BuOCH(2))C(6)H(3)]AsCl (4) as a result of intramolecular cyclization. The organoantimony chloride L(3)SbCl(2) was shown to undergo very slow cyclization in CDCl(3) again via elimination of t-BuCl giving [2-(OCH(2))-6-(t-BuOCH(2))C(6)H(3)]SbCl (6) and it was demonstrated that this reaction may be accelerated by preparation of L(3)Sb(Cl)(OTf) (7) with more Lewis acidic central atom. On the contrary, both antimony derivatives of the NCO ligand L(4), not only the chloride L(4)SbCl(2) (8) but also the ionic pair containing highly Lewis acidic cation [L(4)SbCl](+)[CB(11)H(12)](-) (9), are stable without any indication for etheral bond cleavage. The situation is rather similar in the case of organobismuth derivatives of L(4), which allowed isolation of compounds L(4)BiCl(2) (10), L(4)Bi(Cl)(OTf) (11) and [L(4)BiCl](+)[CB(11)H(12)](-) (12). All studied compounds were characterized by the help of (1)H and (13)C NMR spectroscopy, ESI mass spectrometry, elemental analysis and (except 1) by single-crystal X-ray diffraction.

  15. Experimental PDT: studies on new Si-phthalocyanines and Si-naphthalocyanines in Cremophor emulsions

    NASA Astrophysics Data System (ADS)

    Shopova, Maria; Mantareva, Vanya; Woehrle, Dieter; Mueller, Silke

    1996-12-01

    In the present work the following silicon (IV) - phthalocyanines and -naphthalocyanines bearing methoxyethylene glycol or methoxypolyethylene glycol covalently bound at the silicon are investigated: SiPc[OCH2CH2OCH3]2 (SiPc1), SiNc[OCH2CH2OCH3]2 (SiNc), SiPc[(OCH2CH2)nOCH3] with n approximately 115 (SiPc2). The phototherapeutic effect was shown at Lewis lung carcinoma implanted in mice. SiPc2 is monomeric soluble in water whereas the other two compounds aggregated in this solvent. Therefore these compounds were dissolved monomer in in aqueous Cremophor solution before in vivo administration. Laser irradiation was applied 7 days after implantation and 24 h after drug administration at the following wavelength (eta) ext: 672 nm for SiPc1 and SiPc2, 782 nm for SiNc. In all cases a fluence rate of 370 mW/cm2 at fluence of 360 J/cm2 was used. The assessment criteria for the tumor response were the changes in the mean tumor diameter with time, regrowth delay and average survival time (AST). According to the first parameter the most promising result was obtained after treatment with SiPc1. For example the mean tumor diameter increases as follows: SiPc1 less than SiPc2 less than SiNc very much less than control group without photosensitizer. The regrowth delay showed the same trend. however, for AST another dependence was observed. AST was the longest for SiPc2 (26 days) and shortest for SiNc (22 days). Compared to the control group (without sensitizer and irradiation) the AST was 9 days longer after SiPc2 treatment. Comparing SiPc1 and SiPc2 the chain length of the substituents does not influence the phototherapeutic properties. The detected therapeutic results probably are connected with the long wavelength absorption of the photosensitizers. The relatively lower affectivity of SiNc may be due to a lower degree of tumor accumulation as it was observed in our preliminary pharmacokinetic studies. It is also possible that the shorter AST after treatment with SiNc is

  16. Anion Transport in Liposomes Responds to Variations in the Anchor Chains and the Fourth Amino Acid of Heptapeptide Ion Channels

    PubMed Central

    Ferdani, Riccardo; Pajewski, Robert; Djedovič, Natasha; Pajewska, Jolanta; Schlesinger, Paul H.; Gokel, George W.

    2008-01-01

    Seven heptapeptide derivatives have been prepared. The peptide structure is (Gly)3Xxx(Gly)3 in which Xxx stands for a variable amino acid. The amino acid variations include azetidine carboxylic acid, pipecolic acid, meta-aminobenzoic acid, proline, and leucine. All seven compounds have a C-terminal benzyl group. In all cases, the heptapeptide's N-terminus was linked to diglycolic acid and a dialkylamine. In five cases, the N-terminal group was didecylamine and in two cases, N-ethyl-N-decyl. Chloride and carboxyfluorescein release from phospholipid vesicles was studied with the result that C10H21N(C2H5) COCH2OCH2CO-NH-(Gly)3Leu(Gly)3-OCH2Ph was the most active. Hill analysis showed that this compound involves pore formation by four monomer units rather than two, as previously found for other members of this family. PMID:19169373

  17. Increasing the activity and enantioselectivity of lipases by sol-gel immobilization: further advancements of practical interest.

    PubMed

    Tielmann, Patrick; Kierkels, Hans; Zonta, Albin; Ilie, Adriana; Reetz, Manfred T

    2014-06-21

    The entrapment of lipases in hydrophobic silicate matrices formed by sol-gel mediated hydrolysis of RSi(OCH3)3/Si(OCH3)4 as originally reported in 1996 has been improved over the years by a number of modifications. In the production of second-generation sol-gel lipase immobilizates, a variety of additives during the sol-gel process leads to increased activity and enhanced stereoselectivity in esterifying kinetic resolution. Recent advances in this type of lipase immobilization are reviewed here, in addition to new results regarding the sol-gel entrapment of the lipase from Burkholderia cepacia. It constitutes an excellent heterogeneous biocatalyst in the acylating kinetic resolution of two synthetically and industrially important chiral alcohols, rac-sulcatol and rac-trans-2-methoxycyclohexanol. The observation that the catalyst can be used 10 times in recycling experiments without losing its significant activity or enantioselectivity demonstrates the practical viability of the sol-gel approach.

  18. Saturation of the Large Aperture Scintillometer

    NASA Astrophysics Data System (ADS)

    Kohsiek, W.; Meijninger, W. M. L.; Debruin, H. A. R.; Beyrich, F.

    2006-10-01

    The saturation aspects of a large aperture (0.3 m) scintillometer operating over a 10-km path were investigated. Measurements were made over mainly forested, hilly terrain with typical maximum sensible heat fluxes of 300-400 W m -2, and over flat terrain with mainly grass, and typical maximum heat fluxes of 100-150 W m-2. Scintillometer-based fluxes were compared with eddy-correlation observations. Two different schemes for calculating the reduction of scintillation caused by saturation were applied: one based on the work of Hill and Clifford, the other based on Frehlich and Ochs. Without saturation correction, the scintillation fluxes were lower than the eddy-correlation fluxes; the saturation correction according to Frehlich and Ochs increased the scintillometer fluxes to an unrealistic level. Correcting the fluxes after the theory of the Hill and Clifford gave satisfying results

  19. Synthesis of ketones from biomass-derived feedstock

    NASA Astrophysics Data System (ADS)

    Meng, Qinglei; Hou, Minqiang; Liu, Huizhen; Song, Jinliang; Han, Buxing

    2017-01-01

    Cyclohexanone and its derivatives are very important chemicals, which are currently produced mainly by oxidation of cyclohexane or alkylcyclohexane, hydrogenation of phenols, and alkylation of cyclohexanone. Here we report that bromide salt-modified Pd/C in H2O/CH2Cl2 can efficiently catalyse the transformation of aromatic ethers, which can be derived from biomass, to cyclohexanone and its derivatives via hydrogenation and hydrolysis processes. The yield of cyclohexanone from anisole can reach 96%, and the yields of cyclohexanone derivatives produced from the aromatic ethers, which can be extracted from plants or derived from lignin, are also satisfactory. Detailed study shows that the Pd, bromide salt and H2O/CH2Cl2 work cooperatively to promote the desired reaction and inhibit the side reaction. Thus high yields of desired products can be obtained. This work opens the way for production of ketones from aromatic ethers that can be derived from biomass.

  20. New State Records of Mosquitoes for Colorado.

    PubMed

    Rose, Dominic A; Kondratieff, B C; Weissmann, M J

    2015-06-01

    The 1967 treatment of the Mosquitoes of Colorado by Harmston and Lawson and subsequent publications have recorded 46 culicid species from Colorado. As part of a study to create an updated synopsis of the mosquitoes of Colorado, adult trapping at numerous localities was conducted in Colorado during the summers of 2013 and 2014. This review also included an examination of mosquito specimens in various relevant museum collections. Aedes (Ochlerotatus) niphadopsis and Ae. (Och.) spencerii spencerii were collected during the 2013 and 2014 field seasons. Records for Ae. (Och.) canadensis canadensis, Ae. (Stegomyia) aegypti, and Uranotaenia (Pseudoficalbia) anhydor syntheta were obtained from examination of museum specimens. These species constitute new state records for Colorado, with 51 species now known from the state.

  1. Synthesis of ketones from biomass-derived feedstock

    PubMed Central

    Meng, Qinglei; Hou, Minqiang; Liu, Huizhen; Song, Jinliang; Han, Buxing

    2017-01-01

    Cyclohexanone and its derivatives are very important chemicals, which are currently produced mainly by oxidation of cyclohexane or alkylcyclohexane, hydrogenation of phenols, and alkylation of cyclohexanone. Here we report that bromide salt-modified Pd/C in H2O/CH2Cl2 can efficiently catalyse the transformation of aromatic ethers, which can be derived from biomass, to cyclohexanone and its derivatives via hydrogenation and hydrolysis processes. The yield of cyclohexanone from anisole can reach 96%, and the yields of cyclohexanone derivatives produced from the aromatic ethers, which can be extracted from plants or derived from lignin, are also satisfactory. Detailed study shows that the Pd, bromide salt and H2O/CH2Cl2 work cooperatively to promote the desired reaction and inhibit the side reaction. Thus high yields of desired products can be obtained. This work opens the way for production of ketones from aromatic ethers that can be derived from biomass. PMID:28139709

  2. Method for synthesizing thin film electrodes

    DOEpatents

    Boyle, Timothy J.

    2007-03-13

    A method for making a thin-film electrode, either an anode or a cathode, by preparing a precursor solution using an alkoxide reactant, depositing multiple thin film layers with each layer approximately 500 1000 .ANG. in thickness, and heating the layers to above 600.degree. C. to achieve a material with electrochemical properties suitable for use in a thin film battery. The preparation of the anode precursor solution uses Sn(OCH.sub.2C(CH.sub.3).sub.3).sub.2 dissolved in a solvent in the presence of HO.sub.2CCH.sub.3 and the cathode precursor solution is formed by dissolving a mixture of (Li(OCH.sub.2C(CH.sub.3).sub.3)).sub.8 and Co(O.sub.2CCH.sub.3).H.sub.2O in at least one polar solvent.

  3. Effect of organic substituents on the adsorption of carbon dioxide on a metal-organic framework

    NASA Astrophysics Data System (ADS)

    Thu Ha, Nguyen Thi; Lefedova, O. V.; Ha, Nguyen Ngoc

    2017-01-01

    The adsorption of carbon dioxide on the MOF-5 metal-organic framework and modifications of it obtained by replacing the hydrogen atoms in the organic ligands with electron donor (-CH3,-OCH3) or electron acceptor groups (-CN,-NO2) is investigated using the grand canonical Monte Carlo (GCMC) method and density functional theory (DFT). It is shown that the adsorption of carbon dioxide molecules on the structures of metal-organic frameworks is most likely on Zn4O clusters, and that the adsorption of carbon dioxide is of a physical nature. The presence of substituents-CH3,-OCH3,-CN in metal-organic frameworks increases their capacity to adsorb carbon dioxide, while that of nitro groups (-NO2) has the opposite effect.

  4. The Synthesis and Characterization of Aromatic Hybrid Anderson–Evans POMs and their Serum Albumin Interactions: The Shift from Polar to Hydrophobic Interactions

    PubMed Central

    Al-Sayed, Emir; Blazevic, Amir; Roller, Alexander; Rompel, Annette

    2015-01-01

    Four aromatic hybrid Anderson polyoxomolybdates with Fe3+ or Mn3+ as the central heteroatom have been synthesized by using a pre-functionalization protocol and characterized by using single-crystal X-ray diffraction, FTIR, ESI-MS, 1H NMR spectroscopy, and elemental analysis. Structural analysis revealed the formation of (TBA)3[FeMo6O18{(OCH2)3CNHCOC6H5}2]⋅3.5 ACN (TBA-FeMo6-bzn; TBA=tetrabutylammonium, ACN=acetonitrile, bzn=TRIS-benzoic acid alkanolamide, TRIS–R=(HOCH2)3C–R)), (TBA)3[FeMo6O18{(OCH2)3CNHCOC8H7}2]⋅2.5 ACN (TBA-FeMo6-cin; cin=TRIS-cinnamic acid alkanolamide), (TBA)3[MnMo6O18{(OCH2)3CNHCOC6H5}2]⋅3.5 ACN (TBA-MnMo6-bzn), and (TBA)3[MnMo6O18{(OCH2)3CNHCOC8H7}2]⋅2.5 ACN (TBA-MnMo6-cin). To make these four compounds applicable in biological systems, an ion exchange was performed that gave the water-soluble (up to 80 mm) sodium salts Na3[FeMo6O18{(OCH2)3CNHCOC6H5}2] (Na-FeMo6-bzn), Na3[FeMo6O18{(OCH2)3CNHCOC8H7}2] (Na-FeMo6-cin), Na3[MnMo6O18{(OCH2)3CNHCOC6H5}2] (Na-MnMo6-bzn), and Na3[MnMo6O18{(OCH2)3CNHCOC8H7}2] (Na-MnMo6-cin). The hydrolytic stability of the sodium salts was examined by applying ESI-MS in the pH range of 4 to 9. Sodium dodecylsulfate–polyacrylamide gel electrophoresis (SDS-PAGE) showed that human and bovine serum albumin (HSA and BSA) remain intact in solutions that contain up to 100 equivalents of the sodium salts over more than 4 d at 20 °C. Tryptophan (Trp) fluorescence quenching was applied to study the interactions between the sodium salts and HSA and BSA at pH 5.5 and 7.4. The quenching constants were extracted by using Stern–Volmer analysis, which suggested the formation of a 1:1 POM–protein complex in all samples. It is suggested that the aromatic hybrid POM approaches subdomain IIA of HSA and exhibits hydrophobic interactions with its hydrophobic tails, whereas the Anderson core is stabilized through electrostatic interactions with polar amino acid side chains from, for example

  5. The Synthesis and Characterization of Aromatic Hybrid Anderson-Evans POMs and their Serum Albumin Interactions: The Shift from Polar to Hydrophobic Interactions.

    PubMed

    Al-Sayed, Emir; Blazevic, Amir; Roller, Alexander; Rompel, Annette

    2015-12-01

    Four aromatic hybrid Anderson polyoxomolybdates with Fe(3+) or Mn(3+) as the central heteroatom have been synthesized by using a pre-functionalization protocol and characterized by using single-crystal X-ray diffraction, FTIR, ESI-MS, (1) H NMR spectroscopy, and elemental analysis. Structural analysis revealed the formation of (TBA)3 [FeMo6 O18 {(OCH2 )3 CNHCOC6 H5 }2 ]⋅3.5 ACN (TBA-FeMo6 -bzn; TBA=tetrabutylammonium, ACN=acetonitrile, bzn=TRIS-benzoic acid alkanolamide, TRISR=(HOCH2 )3 CR)), (TBA)3 [FeMo6 O18 {(OCH2 )3 CNHCOC8 H7 }2 ]⋅2.5 ACN (TBA-FeMo6 -cin; cin=TRIS-cinnamic acid alkanolamide), (TBA)3 [MnMo6 O18 {(OCH2 )3 CNHCOC6 H5 }2 ]⋅3.5 ACN (TBA-MnMo6 -bzn), and (TBA)3 [MnMo6 O18 {(OCH2 )3 CNHCOC8 H7 }2 ]⋅2.5 ACN (TBA-MnMo6 -cin). To make these four compounds applicable in biological systems, an ion exchange was performed that gave the water-soluble (up to 80 mM) sodium salts Na3 [FeMo6 O18 {(OCH2 )3 CNHCOC6 H5 }2 ] (Na-FeMo6 -bzn), Na3 [FeMo6 O18 {(OCH2 )3 CNHCOC8 H7 }2 ] (Na-FeMo6 -cin), Na3 [MnMo6 O18 {(OCH2 )3 CNHCOC6 H5 }2 ] (Na-MnMo6 -bzn), and Na3 [MnMo6 O18 {(OCH2 )3 CNHCOC8 H7 }2 ] (Na-MnMo6 -cin). The hydrolytic stability of the sodium salts was examined by applying ESI-MS in the pH range of 4 to 9. Sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that human and bovine serum albumin (HSA and BSA) remain intact in solutions that contain up to 100 equivalents of the sodium salts over more than 4 d at 20 °C. Tryptophan (Trp) fluorescence quenching was applied to study the interactions between the sodium salts and HSA and BSA at pH 5.5 and 7.4. The quenching constants were extracted by using Stern-Volmer analysis, which suggested the formation of a 1:1 POM-protein complex in all samples. It is suggested that the aromatic hybrid POM approaches subdomain IIA of HSA and exhibits hydrophobic interactions with its hydrophobic tails, whereas the Anderson core is stabilized through electrostatic

  6. Associated species in vaporized methanol-formaldehyde solutions

    SciTech Connect

    Silverman, D.C.; Freeman, J.J.

    1983-07-01

    Analysis of vaporized methanolic formaldehyde (50 mol % methanol) by gas chromatography revealed a sum of mole percents of formaldehyde, water, and methanol greater than 100%. This inconsistency was not found with vaporized solutions containing 1 or 10 mol % methanol. Direct evidence for an adduct of methanol and formaldehyde (CH/sub 3/OCH/sub 2/OH) in the vapor phase was found by use of infrared spectroscopy. The spectrum exhibited an absorption at 1140 cm/sup -1/ corresponding to a C-O-C stretch. Reasonable agreement was found between the C-O-C mole percent estimated from infrared spectroscopy, the increased amount of material detected by gas chromatography, and the estimated equilibrium mole percent of the adduct CH/sub 3/OCH/sub 2/OH. These results confirm that in completely vaporized methanolic formaldehyde at 373 to 423 K, one type of adduct predominates. It contains one molecule each of formaldehyde and methanol.

  7. Differentiation of neotropical fish species with statistical analysis of fourier transform infrared photoacoustic spectroscopy data.

    PubMed

    Almeida, Francylaine S; Lima, Sandro M; Andrade, Luis H C; Súarez, Yzel R

    2012-07-01

    Fourier transform infrared photoacoustic spectroscopy (FTIR-PAS) was applied to nineteen fish species in Brazil's Upper Paraná River basin to identify differences in the structural composition of their scales. To differentiate the species, a canonical discriminant analysis was used to indicate the most important absorption peaks in the mid-infrared region. Significant differences were found in the chemical composition of scales among the studied fish species, with Wilk's lambda = 5.2 × 10(-6), F((13,18,394)) = 37.57, and P < 0.001, indicating that O-CH(2) wag at 1396 cm(-1) can be used as a biomarker of this species group. The species could be categorized into four groups according to phylogenetic similarity, suggesting that the O-CH(2) 1396 cm(-1) absorbance is related to the biological traits of each species. This procedure can also be used to complement evolutionary studies.

  8. Organotitanium(IV) compounds as catalysts for the polymerization of isocyanates: The polymerization of isocyanates with functionalized side chains

    SciTech Connect

    Patten, T.E.; Novak, B.M. Lawrence Berkeley Lab., CA )

    1993-02-01

    Catalysts of the form CpTiCl[sub 2]X, where X = [minus]OCH[sub 2]CF[sub 3], [minus]N(CH[sub 3])[sub 2], or [minus]CH[sub 3] (2a, 2b, 2c; Cp = [eta][sup 5]-cyclopentadienyl), CP*TiCl[sub 2]OCH[sub 2]CF[sub 3](3; Cp* = [eta][sup 5]-pentamethylcyclopentadienyl), and Cp[sub 2]TiClOCH[sub 2]-CF[sub 3](4) were used to polymerize a variety of isocyanates. Titanium-alkoxide, -amide, and -alkyl bonds were all found to be active in initiating the insertion of isocyanate monomer. An advantageous consequence of the lesser Lewis acidity of 2a-c relative to TiCl[sub 3]OCH[sub 2]CF[sub 3](1) is that the polymerization of highly functionalized monomers is possible using 2a-c and not 1. 2-Isocyanotoethyl methacrylate (2IEM) was polymerized, using 2b, through the isocyanato group to a linear polymer; the resulting properties of this material were found to be quite different from what was reported by Graham et al. 2IEM trimer was synthesized and subsequently cross-linked using a free-radical initiator, and it was found that the properties of this material matched those of the earlier report. The Diels-Alder adduct of 2IEM with cyclopentadiene, 2-((2-isocyanatoethoxy)carbonyl)-2-methylbicyclo[2.2.1]hept-5-ene (2IECMBH) was prepared and also polymerized using 2b. The use of cyclopentadienyltitanium trichloride derivatives also provides a general route through which a wide variety of end groups may be incorporated onto the end of the polyisocyanate chain.

  9. Chiral Pharmaceutical Intermediaries Obtained by Reduction of 2-Halo-1-(4-substituted phenyl)-ethanones Mediated by Geotrichum candidum CCT 1205 and Rhodotorula glutinis CCT 2182

    PubMed Central

    Fardelone, Lucídio C.; Rodrigues, J. Augusto R.; Moran, Paulo J. S.

    2011-01-01

    Enantioselective reductions of p-R1-C6H4C(O)CH2R2 (R1 = Cl, Br, CH3, OCH3, NO2 and R2 = Br, Cl) mediated by Geotrichum candidum CCT 1205 and Rhodotorula glutinis CCT 2182 afforded the corresponding halohydrins with complementary R and S configurations, respectively, in excellent yield and enantiomeric excesses. The obtained (R)- or (S)-halohydrins are important building blocks in chemical and pharmaceutical industries. PMID:21687613

  10. Utilization of useless pesticides in a plasma reactor

    NASA Astrophysics Data System (ADS)

    Lozhechnik, A. V.; Mossé, A. L.; Savchin, V. V.; Skomorokhov, D. S.; Khvedchin, I. V.

    2011-09-01

    Investigations on destruction of isophene C14H18O7N2 and the butyl ether of 2,4-dichlorophenoxyacetic acid (Cl2C6H3OCH2COOCH2CH(CH3)2) are performed. The plasma treatment of toxic waste is implemented in a plasma reactor with a three-jet mixing chamber. Air is used as the plasma-forming gas.

  11. Cholesteric Liquid Crystal Glass Platinum Acetylides

    DTIC Science & Technology

    2014-06-01

    cholesteric glasses at room temperature, a series of platinum acetylide complexes modified with cholesterol has been synthesized. The materials synthesized...have the formula trans-Pt(PR3)( cholesterol (3 or 4)- ethynyl benzoate)(1-ethynyl-4-X-benzene), where R = Et, Bu or Oct and X = H, F, OCH3 and CN. A...glasses at room temperature, a series of platinum acetylide complexes modified with cholesterol has been synthesized. The materials synthesized

  12. Multilingual Affordances in a Swedish Preschool: An Action Research Project

    ERIC Educational Resources Information Center

    Ljunggren, Åsa

    2016-01-01

    This article summarizes the work and the main findings of an action research project that was conducted in an early childhood education and care setting in the city of Malmö, Sweden in the autumn of 2013 and spring 2014. Rönnerman's model (Aktionsforskning i praktiken: förskola och skola på vetenskaplig grund [Action research in practice:…

  13. Bridge Busters: The 397th Bombardment Group (Medium) and the B-26 Marauder in World War II

    DTIC Science & Technology

    2015-06-01

    BRIDGE BUSTERS: THE 397TH BOMBARDMENT GROUP (MEDIUM) AND THE B-26 MARAUDER IN WORLD WAR II BY LIEUTENANT COLONEL DAVID OCH A THESIS...v ABSTRACT This study examines the concept of medium bombardment and the role of the Martin B-26 Marauder in World War II (WWII) through...1944: The Climactic Battle of World War II (New York: Simon & Schuster, 1994), 239. 2 History, 397th Bombardment Group, June 1944. 2 and capable

  14. Theoretical spectroscopic characterization at low temperatures of S-methyl thioformate and O-methyl thioformate

    SciTech Connect

    Senent, M. L.; Puzzarini, C.; Hochlaf, M.; Domínguez-Gómez, R.; Carvajal, M.

    2014-09-14

    Highly correlated ab initio methods are employed to determine spectroscopic properties at low temperatures of two S-analogs of methyl formate: S-methyl thioformate CH{sub 3}-S-CHO (MSCHO) and O-methyl thioformate CH{sub 3}-O-CHS (MOCHS). Both species are detectable and they are expected to play an important role in Astrochemistry. Molecular properties are compared with those of the O-analog, methyl formate. Both isomers present two conformers cis and trans. cis-CH{sub 3}-S-CHO represents the most stable structure lying 4372.2 cm{sup −1} below cis-CH{sub 3}-O-CHS. The energy difference between the cis and trans forms is drastically lower for MSCHO (1134 cm{sup −1}) than for MOCHS (1963.6 cm{sup −1}). Harmonic and anharmonic fundamentals and the corresponding intensities, as well as the rotational constants for the ground vibrational and first excited torsional states and the centrifugal distortions constants, are provided. Low torsional energy levels have been obtained by solving variationally a two dimensional Hamiltonian expressed in terms of the two torsional degrees of freedom. The corresponding 2D potential energy surfaces have been computed at the CCSD(T)/aug-cc-pVTZ level of theory. The methyl torsional barriers V{sub 3}(cis) are determined to be 139.7 cm{sup −1} (CH{sub 3}-S-CHO) and 670.4 cm{sup −1} (CH{sub 3}-O-CHS). The A/E splitting of ground torsional state has been estimated to be 0.438 cm{sup −1} for CH{sub 3}-S-CHO and negligible for CH{sub 3}-O-CHS.

  15. Energetics and Dynamics of the Reactions of O(3P) with Dimethyl Methylphosphonate and Saria

    DTIC Science & Technology

    2009-09-15

    a SN2 -like transition geometry, Figure 3c, the axial O-C-H bond angle is slightly bent more for reaction 4, Figure 3d. The products of reaction 4 are...Energetics and Dynamics of the Reactions of O(3P) with Dimethyl Methylphosphonate and Sarin Patrick F. Conforti and Matthew Braunstein* Spectral...calculations were performed on the reaction systems O(3P) + sarin and O(3P) + dimethyl methylphosphonate (DMMP), a sarin simulant. Transition state

  16. A theoretical investigation on kinetics, mechanism, and thermochemistry of the gas-phase reactions of methyl fluoroacetate with OH radicals and fate of alkoxy radical.

    PubMed

    Mishra, Bhupesh Kumar; Deka, Ramesh Chandra

    2014-09-25

    We theoretically investigated OH-initiated hydrogen abstraction reactions of methyl fluoroacetate (MFA) CH2FC(O)OCH3 at the MPWB1K level of theory in conjunction with the 6-31+G(d,p) basis set. Thermodynamic and kinetic data are computed using the comparatively accurate G2(MP2) method. Two most stable conformers of MFA are identified, and the energy difference between them is found to be only 0.32 kcal mol(-1). Both of them are considered for rate coefficient calculations, and the contribution from each of the conformers is found to be quite significant. We propose an indirect mechanism due to validation of pre- and post-reactive complexes. The rate parameters are determined using canonical transition state theory and energetics at the G2(MP2) level. The temperature dependence of the rate constant can be described by the Arrhenius expressions: k = 8.79 × 10(-13) exp[(-377.27 ± 64)/T] cm(3) molecule(-1) s(-1) over a temperature range of 250-450 K. The ΔfH°298 for CH2FC(O)OCH3, CH2FC(O)OC(•)H2, and C(•)HFC(O)OCH3 are also computed using an isodesmic procedure. The OH-driven atmospheric lifetime of MFA was estimated to be 24 days. A mechanistic study to shed light on the atmospheric degradation and the sole fate for the consumption of CH2FC(O)OCH2O(•) radical has also been reported.

  17. Minimum structure requirement of immunomodulatory glycolipids for predominant Th2 cytokine induction and the discovery of non-linear phytosphingosine analogs.

    PubMed

    Toba, Tetsuya; Murata, Kenji; Nakanishi, Kyoko; Takahashi, Bitoku; Takemoto, Naohiro; Akabane, Minako; Nakatsuka, Takashi; Imajo, Seiichi; Yamamura, Takashi; Miyake, Sachiko; Annoura, Hirokazu

    2007-05-15

    Analogs of immunomodulatory glycolipid OCH (2) were prepared and minimum structure requirement to exhibit equivalent profiles was disclosed. Analogs bearing non-linear hydrocarbon chain in the phytosphingosine moiety (18, 19) were shown for the first time to possess comparable cytokine inducing profile to 2. Molecular modeling of 2/hCD1d complex based on the crystal structure of alpha-GalCer (1)/hCD1d complex is also described.

  18. Synthesis of Potential Prophylactic Agents against Cyanide Intoxication

    DTIC Science & Technology

    1993-04-12

    compiles th« synthetic procedures described in reports submitted for quarters 9-12 of this contract. We have also colligated structures of all...tingle example of ihn compound class was submitted for biological evaluation this report period, and the physical properties of this agent (1) are...condensation of propiophenone »ith diethyl oxalate (Eq. II) The physical properties of these compounds are summarized in Table 2. a cr, 3 F 4 OCH3 5 CH3

  19. Activation of C-O and C-C bonds and formation of novel HAlOH-ether complexes: an EPR study of the reaction of ground-state Al atoms with methylethyl ether and diethyl ether.

    PubMed

    Brunet, François D; Feola, Julie C; Joly, Helen A

    2012-03-15

    Reaction mixtures, containing Al atoms and methylethyl ether (MEE) or diethyl ether (DEE) in an adamantane matrix, were prepared with the aid of a metal-atom reactor known as a rotating cryostat. The EPR spectra of the resulting products were recorded from 77-260 K, at 10 K intervals. Al atoms were found to insert into methyl-O, ethyl-O, and C-C bonds to form CH(3)AlOCH(2)CH(3), CH(3)OAlCH(2)CH(3), and CH(3)OCH(2)AlCH(3), respectively, in the case of MEE while DEE produced CH(3)CH(2)AlOCH(2)CH(3) and CH(3)AlCH(2)OCH(2)CH(3), respectively. From the intensity of the transition lines attributed to the Al atom C-O insertion products of MEE, insertion into the methyl-O bond is preferred. The Al hyperfine interaction (hfi) extracted from the EPR spectra of the C-O insertion products was greater than that of the C-C insertion products, that is, 5.4% greater for the DEE system and 7% greater for the MEE system. The increase in Al hfi is thought to arise from the increased electron-withdrawing ability of the substituents bonded to Al. Besides HAlOH, resulting from the reaction of Al atoms with adventitious water, novel mixed HAlOH:MEE and HAlOH:DEE complexes were identified with the aid of isotopic studies involving H(2)(17)O and D(2)O. The Al and H hfi of HAlOH were found to decrease upon complex formation. These findings are consistent with the nuclear hfi calculated using a density functional theory (DFT) method with close agreement between theory and experiment occurring at the B3LYP level using a 6-311+G(2df,p) basis set.

  20. Effects of age and sex on copper absorption, turnover, and status

    SciTech Connect

    Johnson, P.E.; Milne, D.B. )

    1991-03-15

    Healthy, free-living men and women aged 20 to 59 years were studied to determine the effects of age and sex on Cu absorption, biological half-life (BH) and status. Additional women who were taking oral contraceptives (OCH) or estrogens were compared to women the same ages who did not take hormones. After an overnight fast, subjects provided a blood sample and ate breakfast labeled with 2.5 {mu}Ci Cu-67. Total Cu-67 ingested was determined after the meal by counting subjects in a whole-body gamma counter. Whole body retention of Cu-67 was monitored by 10 additional counts during the next 21 days. Cu absorption (%A) was calculated by extrapolation of the linear portion of a semi-log plot of % retention vs time. BH was {minus}1n2/slope. %A was significantly greater in women than men aged 20-50, but was not affected by age. BH was not significantly affected by either age or sex. Plasma Cu, enzymatic ceruloplasmin (Cp), and RID Cp were significantly higher in women than men, but SOD and in vitro Cu-67 uptake by RBCs did not differ. None of the biochemical indices were significantly affected by age, except RID Cp, which increased with age. Plasma Cu, enzymatic Cp, and SOD activity were higher in women aged 20-39 taking OCH than in those not taking OCH, but %A and BH did not differ between the groups. Trends in women 50-59 taking estrogen or not were similar to findings for women with/without OCH. These data suggest that dietary Cu requirements may differ between men and women.

  1. Identification of Small Ligands Targeting Breast Cancer by In Vivo Screening of Peptide Libraries in Breast Cancer Patients

    DTIC Science & Technology

    2000-09-01

    Lindgren CG, Ochs HD: Impaired in vivo and in vitro antibody responses to bacteriophage (j)X 174 in juvenile rheumatoid arthritis . J Rheumatol 14(5):957...4 (Adverse Event) (Mild) (Moderate) (Severe) (or Life Threatening;) DERMATOLOGI C Skin none or no change scatter macular or scatter macular or...generalized exfoliative papular eruption papular eruption symptomatic dermatitis or or erythema that is or erythema with macular , papular, ulcerating

  2. Chemistry Within Molecular Clusters

    DTIC Science & Technology

    1990-01-01

    DME )nCH3OCH 2 +). We speculate that this is due to the fragments being consumed by an ion-molecule reaction within the cluster. One likely candidate is...the ion-molecule reaction of the fragment cations with a neutral DME , within the bulk cluster to form a trimethyloxonlum cation intermediate. This...the observed products. We therefore speculate that the DME cluster reactions leading to the same products, should involve the same mechanism found to

  3. Chemistry Within Molecular Clusters

    DTIC Science & Technology

    1992-06-01

    and ( DME ).CH 3OCH2+). We speculate that this is due to the fragments being consumed by an ion-molecule reaction within the cluster. A likely candidate...is the ion-molecule reaction of the fragment cations with a neutral DME within the bulk cluster, to form a trimethyloxonium cation intermediate...a trimethyloxonium intermediate as the common intermediate for the observed products. We therefore speculate that the DME cluster reactions leading to

  4. Theoretical spectroscopic characterization at low temperatures of S-methyl thioformate and O-methyl thioformate.

    PubMed

    Senent, M L; Puzzarini, C; Hochlaf, M; Domínguez-Gómez, R; Carvajal, M

    2014-09-14

    Highly correlated ab initio methods are employed to determine spectroscopic properties at low temperatures of two S-analogs of methyl formate: S-methyl thioformate CH3-S-CHO (MSCHO) and O-methyl thioformate CH3-O-CHS (MOCHS). Both species are detectable and they are expected to play an important role in Astrochemistry. Molecular properties are compared with those of the O-analog, methyl formate. Both isomers present two conformers cis and trans. cis-CH3-S-CHO represents the most stable structure lying 4372.2 cm(-1) below cis-CH3-O-CHS. The energy difference between the cis and trans forms is drastically lower for MSCHO (1134 cm(-1)) than for MOCHS (1963.6 cm(-1)). Harmonic and anharmonic fundamentals and the corresponding intensities, as well as the rotational constants for the ground vibrational and first excited torsional states and the centrifugal distortions constants, are provided. Low torsional energy levels have been obtained by solving variationally a two dimensional Hamiltonian expressed in terms of the two torsional degrees of freedom. The corresponding 2D potential energy surfaces have been computed at the CCSD(T)/aug-cc-pVTZ level of theory. The methyl torsional barriers V3(cis) are determined to be 139.7 cm(-1) (CH3-S-CHO) and 670.4 cm(-1) (CH3-O-CHS). The A/E splitting of ground torsional state has been estimated to be 0.438 cm(-1) for CH3-S-CHO and negligible for CH3-O-CHS.

  5. Synthesis, characterization, and OFET properties of amphiphilic heteroleptic tris(phthalocyaninato) europium(III) complexes with hydrophilic poly(oxyethylene) substituents.

    PubMed

    Li, Renjie; Ma, Pan; Dong, Shuai; Zhang, Xianyao; Chen, Yanli; Li, Xiyou; Jiang, Jianzhuang

    2007-12-24

    A series of amphiphilic heteroleptic tris(phthalocyaninato) europium complexes with hydrophilic poly(oxyethylene) heads and hydrophobic alkoxy tails {Pc[(OC2H4)2OCH3]8}Eu{Pc[(OC2H4)2OCH3]8}Eu[Pc(OCnH2n + 1)8] (n = 6, 8, 10,12) (1-4) were designed and prepared from the reaction between homoleptic bis(phthalocyaninato) europium compound {Pc[(OC2H4)2OCH3]8}Eu{Pc[(OC2H4)2OCH3]8} and metal-free 2,3,9,10,16,17,23,24-octakis(alkoxy)phthalocyanine H2Pc(OCnH2n + 1)8 (n = 6, 8, 10,12) in the presence of Eu(acac)3.H2O (Hacac = acetylacetone) in boiling 1,2,4-trichlorobenzene (TCB). These novel sandwich triple-decker complexes have been characterized by a wide range of spectroscopic methods and have been electrochemically studied. With the help of the Langmuir-Blodgett (LB) technique, these typical amphiphilic triple-decker complexes have been fabricated into organic field effect transistors (OFET) with an unusual bottom contact configuration. The devices display good OFET performance with the carrier mobility for holes in the direction parallel to the aromatic phthalocyanine rings, which shows dependence on the length of the hydrophobic alkoxy side chains, decreasing from 0.46 for 1 to 0.014 cm2 V(-1) s(-1) for 4 along with the increase in the carbon number in the hydrophobic alkoxy side chains.

  6. Synthesis and Characterization of New Phosphazene Polymers.

    DTIC Science & Technology

    1988-01-21

    reaction of a poly( alkyl /arylphosphazene). In this study, one-half of the methyl groups in [Ph(Me)PN]n (chosen for its solubility in THF as opposed to...polymerization reaction ; and (5) the derivative chemistry of the preformed poly( alkyl /arylphosphazenes)., Synthesis of Poly( alkyl /arylphosphazenes) SC A... vessels , these phosphoranimines quantitatively eliminate the silyl ether byproduct, Me3SiOCH2CF 3 , to form the poly( alkyl /arylphosphazenes). The synthesis

  7. Gas-phase oxidation of methyl crotonate and ethyl crotonate. kinetic study of their reactions toward OH radicals and Cl atoms.

    PubMed

    Teruel, Mariano A; Benitez-Villalba, Julio; Caballero, Norma; Blanco, María B

    2012-06-21

    Rate coefficients for the reactions of hydroxyl radicals and chlorine atoms with methyl crotonate and ethyl crotonate have been determined at 298 K and atmospheric pressure. The decay of the organics was monitored using gas chromatography with flame ionization detection (GC-FID), and the rate constants were determined using the relative rate method with different reference compounds. Room temperature rate coeficcients were found to be (in cm(3) molecule(-1) s(-1)): k(1)(OH + CH(3)CH═CHC(O)OCH(3)) = (4.65 ± 0.65) × 10(-11), k(2)(Cl + CH(3)CH═CHC(O)OCH(3)) = (2.20 ± 0.55) × 10(-10), k(3)(OH + CH(3)CH═CHC(O)OCH(2)CH(3)) = (4.96 ± 0.61) × 10(-11), and k(4)(Cl + CH(3)CH═CHC(O)OCH(2)CH(3)) = (2.52 ± 0.62) × 10(-10) with uncertainties representing ±2σ. This is the first determination of k(1), k(3), and k(4) under atmospheric pressure. The rate coefficients are compared with previous determinations for other unsaturated and oxygenated VOCs and reactivity trends are presented. In addition, a comparison between the experimentally determined k(OH) with k(OH) predicted from k vs E(HOMO) relationships is presented. On the other hand, product identification under atmospheric conditions has been performed for the first time for these unsaturated esters by the GC-MS technique in NO(x)-free conditions. 2-Hydroxypropanal, acetaldehyde, formaldehyde, and formic acid were positively observed as degradation products in agreement with the addition of OH to C2 and C3 of the double bond, followed by decomposition of the 2,3- or 3,2-hydroxyalkoxy radicals formed. Atmospheric lifetimes, based on of the homogeneous sinks of the unsaturated esters studied, are estimated from the kinetic data obtained in the present work.

  8. Unimolecular thermal decomposition of dimethoxybenzenes

    SciTech Connect

    Robichaud, David J. Mukarakate, Calvin; Nimlos, Mark R.; Scheer, Adam M.; Ormond, Thomas K.; Buckingham, Grant T.; Ellison, G. Barney

    2014-06-21

    The unimolecular thermal decomposition mechanisms of o-, m-, and p-dimethoxybenzene (CH{sub 3}O-C{sub 6}H{sub 4}-OCH{sub 3}) have been studied using a high temperature, microtubular (μtubular) SiC reactor with a residence time of 100 μs. Product detection was carried out using single photon ionization (SPI, 10.487 eV) and resonance enhanced multiphoton ionization (REMPI) time-of-flight mass spectrometry and matrix infrared absorption spectroscopy from 400 K to 1600 K. The initial pyrolytic step for each isomer is methoxy bond homolysis to eliminate methyl radical. Subsequent thermolysis is unique for each isomer. In the case of o-CH{sub 3}O-C{sub 6}H{sub 4}-OCH{sub 3}, intramolecular H-transfer dominates leading to the formation of o-hydroxybenzaldehyde (o-HO-C{sub 6}H{sub 4}-CHO) and phenol (C{sub 6}H{sub 5}OH). Para-CH{sub 3}O-C{sub 6}H{sub 4}-OCH{sub 3} immediately breaks the second methoxy bond to form p-benzoquinone, which decomposes further to cyclopentadienone (C{sub 5}H{sub 4}=O). Finally, the m-CH{sub 3}O-C{sub 6}H{sub 4}-OCH{sub 3} isomer will predominantly follow a ring-reduction/CO-elimination mechanism to form C{sub 5}H{sub 4}=O. Electronic structure calculations and transition state theory are used to confirm mechanisms and comment on kinetics. Implications for lignin pyrolysis are discussed.

  9. Calcium-based Lewis acid catalysts.

    PubMed

    Begouin, Jeanne-Marie; Niggemann, Meike

    2013-06-17

    Recently, Lewis acidic calcium salts bearing weakly coordinating anions such as Ca(NTf₂)₂, Ca(OTf)₂, CaF₂ and Ca[OCH(CF₃)₂]₂ have been discovered as catalysts for the transformation of alcohols, olefins and carbonyl compounds. High stability towards air and moisture, selectivity and high reactivity under mild reaction conditions render these catalysts a sustainable and mild alternative to transition metals, rare-earth metals or strong Brønsted acids.

  10. New Record and Updated Checklists of the Mosquitoes of Afghanistan and Iraq

    DTIC Science & Technology

    2008-08-12

    claviger (Meigen). Although Buck et al. (1972), Ward (1972), Danilov (1985a, 1985b) reported Cx. univittatus Theobald from Afghanistan, it actually...refers to Cx. perexiguus Theobald according to Harbach (1988). Danilov (1978) stated that Ae. versicolor (Barraud) “may be expected in the mountain...K Ae.(Och. pulcritarsis (Rondani) D - Ae. (Stegomyia) aegypti (Linnaeus) - Anopheles (Anopheles) algeriensis Theobald A3, D, G, W, X A2, G, P An

  11. Comments on the ring-opening polymerization of morpholine-2,5-dione derivatives by various metal catalysts and characterization of the products formed in the reactions involving R2SnX2, where X = OPr(i) and NMe2 and R = Bu(n), Ph and p-Me2NC6H4.

    PubMed

    Chisholm, M H; Galucci, J; Krempner, C; Wiggenhorn, C

    2006-02-14

    (3S,6S)-3-Isopropyl-6-methyl-morpholine-2,5-dione (1), and (3S,6S)-3,6-dimethyl-morpholine-2,5-dione (2), do not enter into ring-opening polymerization reactions with metal catalyst precursors commonly employed for lactides, and with Sn(II) octanoate, only low molecular weight oligomers are obtained. Reactions with R2SnX2 compounds, where R = Ph, Bu(n) and p-Me2NC6H4 and X = OPr(i) or NMe2, reveal that ring-opening of the morpholine-2,5-diones does occur, but that polymerization is terminated by the formation of kinetically-inert products such as {Ph2Sn[mu,eta(3)-OCH(Me)CONCH(Pr(i))COOPr(i)]}2 (3), and {[Bu(n))2Sn[mu,eta(3)-OCH(Me)CONCH(Me)CONMe2]}2 (4), with elimination of HX. Ph3SnOPr(i) is seen to react reversibly with morpholine-2,5-diones in toluene-d8 by 1H NMR spectroscopy while (Bu(n))3SnNMe2 reacts by ring opening to give (Bu(n))3SnOCH(Me)C(O)NHCHMeC(O)NMe2. The new organotin compounds have been characterized by 1H, 13C{1H} and 118Sn NMR spectroscopy and compounds 1, 2, 3 and 4 by single crystal X-ray crystallography.

  12. Crystal structures of triazine-3-thione derivatives by reaction with copper and cobalt salts.

    PubMed

    López-Torres, Elena; Mendiola, Maria Antonia; Pastor, César J

    2006-04-03

    The reaction of 5-methoxy-5,6-diphenyl-4,5-dihydro-2H-[1,2,4]triazine-3-thione L1H2OCH3 with copper(II) chloride leads to the formation of an organic molecule L2 containing two triazine rings linked by a new S-S bond. A binuclear copper(II) complex, 1, containing L1 is also isolated. The reaction of L1H2OCH3 with copper(I) chloride yields a hexanuclear cluster of copper(I), 2, in which the copper atoms form a distorted octahedron with the ligand L1 acting as an NS chelate and sulfur bridge, giving to the copper ion a trigonal geometry by one N and two S atoms. In any reaction of the disulfide L2 with metal salts, complexes containing this molecule are isolated. Reactions with copper(I) and copper(II) chloride and nickel(II) and cadmium(II) nitrate produce the S-S bond cleavage, giving complexes containing the triazine L1 behaving as the NS anion, which show spectroscopic characteristics identical with those formed by reaction with L1H2OCH3. However, the reaction with cobalt(II) nitrate gives a low-spin octahedral cobalt(III) complex, in which an asymmetric rupture of the disulfide L2 has been produced, giving an unexpected complex with a new ligand and keeping the S-S bond.

  13. Mechanisms for glycolipid antigen-driven cytokine polarization by Valpha14i NKT cells.

    PubMed

    Sullivan, Barbara A; Nagarajan, Niranjana A; Wingender, Gerhard; Wang, Jing; Scott, Iain; Tsuji, Moriya; Franck, Richard W; Porcelli, Steven A; Zajonc, Dirk M; Kronenberg, Mitchell

    2010-01-01

    Certain glycolipid Ags for Valpha14i NKT cells can direct the overall cytokine balance of the immune response. Th2-biasing OCH has a lower TCR avidity than the most potent agonist known, alpha-galactosylceramide. Although the CD1d-exposed portions of OCH and alpha-galactosylceramide are identical, structural analysis indicates that there are subtle CD1d conformational differences due to differences in the buried lipid portion of these two Ags, likely accounting for the difference in antigenic potency. Th1-biasing C-glycoside/CD1d has even weaker TCR interactions than OCH/CD1d. Despite this, C-glycoside caused a greater downstream activation of NK cells to produce IFN-gamma, accounting for its promotion of Th1 responses. We found that this difference correlated with the finding that C-glycoside/CD1d complexes survive much longer in vivo. Therefore, we suggest that the pharmacokinetic properties of glycolipids are a major determinant of cytokine skewing, suggesting a pathway for designing therapeutic glycolipids for modulating invariant NKT cell responses.

  14. Fluorine in drug design: a case study with fluoroanisoles.

    PubMed

    Xing, Li; Blakemore, David C; Narayanan, Arjun; Unwalla, Ray; Lovering, Frank; Denny, R Aldrin; Zhou, Huanyu; Bunnage, Mark E

    2015-04-01

    Anisole and fluoroanisoles display distinct conformational preferences, as evident from a survey of their crystal structures. In addition to altering the free ligand conformation, various degrees of fluorination have a strong impact on physicochemical and pharmacokinetic properties. Analysis of anisole and fluoroanisole matched molecular pairs in the Pfizer corporate database reveals interesting trends: 1) PhOCF3 increases log D by ~1 log unit over PhOCH3 compounds; 2) PhOCF3 shows lower passive permeability despite its higher lipophilicity; and 3) PhOCF3 does not appreciably improve metabolic stability over PhOCH3 . Emerging from the investigation, difluoroanisole (PhOCF2 H) strikes a better balance of properties with noticeable advantages of log D and transcellular permeability over PhOCF3 . Synthetic assessment illustrates that the routes to access difluoroanisoles are often more straightforward than those for trifluoroanisoles. Whereas replacing PhOCH3 with PhOCF3 is a common tactic to optimize ADME properties, our analysis suggests PhOCF2 H may be a more attractive alternative, and greater exploitation of this motif is recommended.

  15. Origin of Substituent Effect on Tautomeric Behavior of 1,2,4-Triazole Derivatives: Combined Spectroscopic and Theoretical Study.

    PubMed

    Sergeieva, Tetiana; Bilichenko, Maria; Holodnyak, Sergiy; Monaykina, Yulia V; Okovytyy, Sergiy I; Kovalenko, Sergiy I; Voronkov, Eugene; Leszczynski, Jerzy

    2016-12-29

    The reaction of 2-aryl-[1,2,4]triazolo[1,5-c]quinazolines with nucleophilic reagents (hydrazine hydrate, sodium hydroxide, sodium methoxide, hydrochloric acid) under acidic conditions leads to formation of compounds that tend to tautomerize. The products of the transformation are distinguished by the position (ortho-, meta-, para-) of the OCH3 group in the aryl moiety. To assign their structures we used the combined approach: experiment and theoretical modeling. The procedure included calculation of the relative stability for possible tautomers, simulation of UV/vis spectra for the most stable forms, and comparison of the resulting curves with the experimental spectral data taking into account the Boltzmann weighting. Through computations, we showed that the orientation of OCH3 substituent remarkably impacts on the tautomeric behavior of triazoles. In the case of ortho-OCH3 it is controlled by formation of the intramolecular hydrogen bond while for meta- and para- derivatives the degree of conjugation plays the decisive role. In order to balance the accuracy and cost of calculations we evaluated the performance of selected DFT methods and 6-31G*, 6-311++G**, and STO(##)-3Gel basis sets. The last one is a physically justified basis set previously constructed in our group, and its combination with PBE1PBE approach is shown to be the best choice for UV/vis simulations in the frame of the current research.

  16. Structural characterization of a beta-diketone hydrolase from the cyanobacterium Anabaena sp. PCC 7120 in native and product-bound forms, a coenzyme A-independent member of the crotonase suprafamily.

    PubMed

    Bennett, Joseph P; Whittingham, Jean L; Brzozowski, A Marek; Leonard, Philip M; Grogan, Gideon

    2007-01-09

    The gene alr4455 from the well-studied cyanobacterium Anabaena sp. PCC 7120 encodes a crotonase orthologue that displays beta-diketone hydrolase activity. Anabaena beta-diketone hydrolase (ABDH), in common with 6-oxocamphor hydrolase (OCH) from Rhodococcus sp. NCIMB 9784, catalyzes the desymmetrization of bicyclo[2.2.2]octane-2,6-dione to yield [(S)-3-oxocyclohexyl]acetic acid, a reaction unusual among the crotonase superfamily as the substrate is not an acyl-CoA thioester. The structure of ABDH has been determined to a resolution of 1.5 A in both native and ligand-bound forms. ABDH forms a hexamer similar to OCH and features one active site per enzyme monomer. The arrangement of side chains in the active site indicates that while the catalytic chemistry may be conserved in OCH orthologues, the structural determinants of substrate specificity are different. In the active site of ligand-bound forms that had been cocrystallized with the bicyclic diketone substrate bicyclo[2.2.2]octane-2,6-dione was found the product of the asymmetric enzymatic retro-Claisen reaction [(S)-3-oxocyclohexyl]acetic acid. The structures of ABDH in both native and ligand-bound forms reveal further details about structural variation and modes of coenzyme A-independent activity within the crotonases and provide further evidence of a wider suprafamily of enzymes that have recruited the crotonase fold for the catalysis of reactions other than those regularly attributed to canonical superfamily members.

  17. Substituent effects on hydrogen bonding of aromatic amide-carboxylate

    NASA Astrophysics Data System (ADS)

    Sen, Ibrahim; Kara, Hulya; Azizoglu, Akın

    2016-10-01

    N-(p-benzoyl)-anthranilic acid (BAA) derivatives have been synthesized with different substituents (X: Br, Cl, OCH3, CH3), and their crystal structures have been analyzed in order to understand the variations in their molecular geometries with respect to the substituents by using 1H NMR, 13C NMR, IR and X-ray single-crystal diffraction. The carboxylic acid group forms classic Osbnd H ⋯ O hydrogen bonded dimers in a centrosymmetric R22(8) ring motifs for BAA-Br and BAA-Cl. However, no carboxylic acid group forms classic Osbnd H ⋯ O hydrogen bonded dimers in BAA-OCH3 and BAA-CH3. The asymmetric unit consists of two crystallographically independent molecules in BAA-OCH3. DFT computations show that the interaction energies between monomer and dimer are in the range of 0.5-3.8 kcal/mol with the B3LYP/6-31 + G*, B3LYP/6-31 ++G*, B3LYP/6-31 ++G**, and B3LYP/AUG-cc-pVDZ levels of theory. The presence of different hydrogen bond patterns is also governed by the substrate. For monomeric compounds studied herein, theoretical calculations lead to two low-energy conformers; trans (a) and cis (b). Former one is more stable than latter by about 4 kcal/mol.

  18. Substituent effects on hydrogen bonding of aromatic amide-carboxylate.

    PubMed

    Sen, Ibrahim; Kara, Hulya; Azizoglu, Akın

    2016-10-05

    N-(p-benzoyl)-anthranilic acid (BAA) derivatives have been synthesized with different substituents (X: Br, Cl, OCH3, CH3), and their crystal structures have been analyzed in order to understand the variations in their molecular geometries with respect to the substituents by using (1)H NMR, (13)C NMR, IR and X-ray single-crystal diffraction. The carboxylic acid group forms classic OH⋯O hydrogen bonded dimers in a centrosymmetric R2(2)(8) ring motifs for BAA-Br and BAA-Cl. However, no carboxylic acid group forms classic OH⋯O hydrogen bonded dimers in BAA-OCH3 and BAA-CH3. The asymmetric unit consists of two crystallographically independent molecules in BAA-OCH3. DFT computations show that the interaction energies between monomer and dimer are in the range of 0.5-3.8kcal/mol with the B3LYP/6-31+G*, B3LYP/6-31++G*, B3LYP/6-31++G**, and B3LYP/AUG-cc-pVDZ levels of theory. The presence of different hydrogen bond patterns is also governed by the substrate. For monomeric compounds studied herein, theoretical calculations lead to two low-energy conformers; trans (a) and cis (b). Former one is more stable than latter by about 4kcal/mol.

  19. Photoelectron velocity-map imaging spectroscopic and theoretical study on the reactivity of the gold atom toward CH3SH, CH3OH, and H2O.

    PubMed

    Qin, Zhengbo; Cong, Ran; Wu, Xia; Liu, Zhiling; Xie, Hua; Tang, Zichao; Jiang, Ling; Fan, Hongjun

    2013-07-21

    Photoelectron velocity-map imaging spectroscopy has been used to study the reaction of the anionic gold atom with the HR (R = SCH3, OCH3, OH) molecules. The solvated [Au···HR](-) and inserted [HAuR](-) products have been experimentally observed for R = SCH3, whereas only solvated [Au⋯HR](-) products were found for R = OCH3 and OH. This significant difference in the photoelectron spectra suggests the different reactivity of the Au(-) toward the CH3SH, CH3OH, and H2O molecules. Second order Møller-Plesset perturbation theory and coupled-cluster single double triple excitation calculations have been performed to aid the structural assignment of the spectra and to explore the reaction mechanism. Activation energies for the isomerizations of the solvated structures to the inserted ones in the Au(-)∕Au + HR reactions (R = OCH3 and OH) are predicted to be much higher than those for the Au(-)∕Au + CH3SH reactions, supporting the experimental observation. Theoretical calculations provide the evidence that the intriguing [HAuSCH3](-) product may be formed by the attachment of the electron onto the neutral HAuSCH3 species or the isomerization from the anionic [Au···HSCH3](-) one. These findings should be helpful for understanding the feature that the thiols are able to form the staple motifs, whereas CH3OH and H2O are not.

  20. Hydrogen production for fuel cells through methane reforming at low temperatures

    NASA Astrophysics Data System (ADS)

    Liu, Zhong-Wen; Jun, Ki-Won; Roh, Hyun-Seog; Park, Sang-Eon

    Hydrogen production for fuel cells through methane (CH 4) reforming at low temperatures has been investigated both thermodynamically and experimentally. From the thermodynamic equilibrium analysis, it is concluded that steam reforming of CH 4 (SRM) at low pressure and a high steam-to-CH 4 ratio can be achieved without significant loss of hydrogen yield at a low temperature such as 550 °C. A scheme for the production of hydrogen for fuel cells at low temperatures by burning the unconverted CH 4 to supply the heat for SRM is proposed and the calculated value of the heat-balanced temperature is 548 °C. SRM with and/or without the presence of oxygen at low temperatures is experimentally investigated over a Ni/Ce-ZrO 2/θ-Al 2O 3 catalyst. The catalyst shows high activity and stability towards SRM at temperatures from 400 to 650 °C. The effects of O 2:CH 4 and H 2O:CH 4 ratios on the conversion of CH 4, the hydrogen yield, the selectivity for carbon monoxide, and the H 2:CO ratio are investigated at 650 °C with a constant CH 4 space velocity. Results indicate that CH 4 conversion increases significantly with increasing O 2:CH 4 or H 2O:CH 4 ratio, and the hydrogen content in dry tail gas increases with the H 2O:CH 4 ratio.

  1. Vibrational Spectra and Adsorption of Trisiloxane Superspreading Surfactant at Air/Water Interface Studied with Sum Frequency Generation Vibrational Spectroscopy

    NASA Astrophysics Data System (ADS)

    Feng, Jun; Wu, Dan; Wen, Jia; Liu, Shi-lin; Wang, Hong-fei

    2008-08-01

    The C-H stretch vibrational spectra of the trisiloxane superspreading surfactant Silwet L-77 ((CH3)3Si-O-Si(CH3)(C3H6)(OCH2CH2)7-8OCH3)-O-Si(CH3)3) at the air/water interface are measured with the surface Sum Frequency Generation Vibrational Spectroscopy (SFG-VS). The spectra are dominated with the features from the -Si-CH3 groups around 2905 cm-1 (symmetric stretch or SS mode) and 2957 cm-1 (mostly the asymmetric stretch or AS mode), and with the weak but apparent contribution from the -O-CH2- groups around 2880 cm-1 (symmetric stretch or SS mode). Comparison of the polarization dependent SFG spectra below and above the critical aggregate or micelle concentration (CAC) indicates that the molecular orientation of the C-H related molecular groups remained unchanged at different surface densities of the Silwet L-77 surfactant. The SFG-VS adsorption isotherm suggested that there was no sign of Silwet L-77 bilayer structure formation at the air/water interface. The Gibbs adsorption free energy of the Silwet surfactant to the air/water interface is -42.2±0.8kcal/mol, indicating the unusually strong adsorption ability of the Silwet L-77 superspreading surfactant.

  2. Study of RF-excited Diethylene Glycol Dimethyl Ether Plasmas by Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Algatti, M. A.; Mota, R. P.; Moreira Júnior, P. W. P.; Honda, R. Y.; Kayama, M. E.; Kostov, K. G.

    2012-12-01

    This paper deals with the study of the fragmentation process of diethylene glycol dimethyl ether (CH3O(CH2CH2O)2CH3) (diglyme here in) molecule in low pressure RF excited plasma discharges. The study was carried out using mass spectrometry. The results showed that for a fixed pressure, the increase of the RF power coupled to the plasma chamber from 1 to 35 W produced a plasma environment much more reactive which increases the population of the ionized species like CH2+ (15 amu), C2H4+ (28 amu), CH3O+ (31 amu), C2H4O+ (44 amu), CH3OCH2CH2+ (59 amu) and CH3OCH2CH2O+ (75 amu). This fact may be attributed to the increase of the electronic temperature that makes predominant the occurrence of inelastic processes that promotes molecular fragmentation. For a fixed value of RF power the increase of pressure from 50 mTorr to 100 mTorr produces the decreasing of the above mentioned chemical species due the lower electronic mean free path. These results suggest that if one wants to keep the monomer's functionality within the plasma deposited films resulting from such kind of discharges one must operate in low power conditions.

  3. Dual-level direct dynamics studies for the reactions of dimethyl ether with hydrogen atom and methyl radical.

    PubMed

    Wu, Jia-Yan; Liu, Jing-Yao; Li, Ze-Sheng; Huang, Xu-Ri; Sun, Chia-Chung

    2003-04-15

    The dual-level direct dynamics approach is employed to study the dynamics of the CH(3)OCH(3) + H (R1) and CH(3)OCH(3) + CH(3) (R2) reactions. Low-level calculations of the potential energy surface are carried out at the MP2/6-311+G(d,p) level of theory. High-level energetic information is obtained at the QCISD(T) level of theory with the 6-311+G(3df,3pd) basis set. The dynamics calculations are performed using variational transition state theory (VTST) with the interpolated single-point energies (ISPE) method, and small-curvature tunneling (SCT) is included. It is shown that the reaction of CH(3)OCH(3) with H (R1) may proceed much easier and with a lower barrier height than the reaction with CH(3) radical (R2). The calculated rate constants and activation energies are in good agreement with the experimental values. The calculated rate constants are fitted to k(R1) = 1.16 x 10(-19) T(3) exp(-1922/T) and k(R2) = 1.66 x 10(-28) T(5) exp(-3086/T) cm(3) mol(-1) s(-1) over a temperature range 207-2100 K. Furthermore, a small variational effect and large tunneling effect in the lower temperature range are found for the two reactions.

  4. Saccharomyces Cerevisiae Hoc1, a Suppressor of Pkc1, Encodes a Putative Glycosyltransferase

    PubMed Central

    Neiman, A. M.; Mhaiskar, V.; Manus, V.; Galibert, F.; Dean, N.

    1997-01-01

    The Saccharomyces cerevisiae gene PKC1 encodes a protein kinase C isozyme that regulates cell wall synthesis. Here we describe the characterization of HOC1, a gene identified by its ability to suppress the cell lysis phenotype of pkc1-371 cells. The HOC1 gene (Homologous to OCH1) is predicted to encode a type II integral membrane protein that strongly resembles Och1p, an α-1,6-mannosyltransferase. Immunofluorescence studies localized Hoc1p to the Golgi apparatus. While overexpression of HOC1 rescued the pkc1-371 temperature-sensitive cell lysis phenotype, disruption of HOC1 lowered the restrictive temperature of the pkc1-371 allele. Disruption of HOC1 also resulted in hypersensitivity to Calcofluor White and hygromycin B, phenotypes characteristic of defects in cell wall integrity and protein glycosylation, respectively. The function of HOC1 appears to be distinct from that of OCH1. Taken together, these results suggest that HOC1 encodes a Golgi-localized putative mannosyltransferase required for the proper construction of the cell wall. PMID:9055074

  5. Methyl-perfluoroheptene-ethers (CH3OC7F13): measured OH radical reaction rate coefficients for several isomers and enantiomers and their atmospheric lifetimes and global warming potentials.

    PubMed

    Jubb, Aaron M; Gierczak, Tomasz; Baasandorj, Munkhbayar; Waterland, Robert L; Burkholder, James B

    2014-05-06

    Mixtures of methyl-perfluoroheptene-ethers (CH3OC7F13, MPHEs) are currently in use as replacements for perfluorinated alkanes (PFCs) and poly-ether heat transfer fluids, which are persistent greenhouse gases with lifetimes >1000 years. At present, the atmospheric processing and environmental impact from the use of MPHEs is unknown. In this work, rate coefficients at 296 K for the gas-phase reaction of the OH radical with six key isomers (including stereoisomers and enantiomers) of MPHEs used commercially were measured using a relative rate method. Rate coefficients for the six MPHE isomers ranged from ∼ 0.1 to 2.9 × 10(-12) cm(3) molecule(-1) s(-1) with a strong stereoisomer and -OCH3 group position dependence; the (E)-stereoisomers with the -OCH3 group in an α- position relative to the double bond had the greatest reactivity. Rate coefficients measured for the d3-MPHE isomer analogues showed decreased reactivity consistent with a minor contribution of H atom abstraction from the -OCH3 group to the overall reactivity. Estimated atmospheric lifetimes for the MPHE isomers range from days to months. Atmospheric lifetimes, radiative efficiencies, and global warming potentials for these short-lived MPHE isomers were estimated based on the measured OH rate coefficients along with measured and theoretically calculated MPHE infrared absorption spectra. Our results highlight the importance of quantifying the atmospheric impact of individual components in an isomeric mixture.

  6. Self-Assembled Amphiphilic Water Oxidation Catalysts: Control of O-O Bond Formation Pathways by Different Aggregation Patterns.

    PubMed

    Yang, Bing; Jiang, Xin; Guo, Qing; Lei, Tao; Zhang, Li-Ping; Chen, Bin; Tung, Chen-Ho; Wu, Li-Zhu

    2016-05-17

    The oxidation of water to molecular oxygen is the key step to realize water splitting from both biological and chemical perspective. In an effort to understand how water oxidation occurs on a molecular level, a large number of molecular catalysts have been synthesized to find an easy access to higher oxidation states as well as their capacity to make O-O bond. However, most of them function in a mixture of organic solvent and water and the O-O bond formation pathway is still a subject of intense debate. Herein, we design the first amphiphilic Ru-bda (H2 bda=2,2'-bipyridine-6,6'-dicarboxylic acid) water oxidation catalysts (WOCs) of formula [Ru(II) (bda)(4-OTEG-pyridine)2 ] (1, OTEG=OCH2 CH2 OCH2 CH2 OCH3 ) and [Ru(II) (bda)(PySO3 Na)2 ] (2, PySO3 (-) =pyridine-3-sulfonate), which possess good solubility in water. Dynamic light scattering (DLS), scanning electron microscope (SEM), critical aggregation concentration (CAC) experiments and product analysis demonstrate that they enable to self-assemble in water and form the O-O bond through different routes even though they have the same bda(2-) backbone. This work illustrates for the first time that the O-O bond formation pathway can be regulated by the interaction of ancillary ligands at supramolecular level.

  7. Photoelectron velocity-map imaging spectroscopic and theoretical study on the reactivity of the gold atom toward CH3SH, CH3OH, and H2O

    NASA Astrophysics Data System (ADS)

    Qin, Zhengbo; Cong, Ran; Wu, Xia; Liu, Zhiling; Xie, Hua; Tang, Zichao; Jiang, Ling; Fan, Hongjun

    2013-07-01

    Photoelectron velocity-map imaging spectroscopy has been used to study the reaction of the anionic gold atom with the HR (R = SCH3, OCH3, OH) molecules. The solvated [Au⋯HR]- and inserted [HAuR]- products have been experimentally observed for R = SCH3, whereas only solvated [Au⋯HR]- products were found for R = OCH3 and OH. This significant difference in the photoelectron spectra suggests the different reactivity of the Au- toward the CH3SH, CH3OH, and H2O molecules. Second order Møller-Plesset perturbation theory and coupled-cluster single double triple excitation calculations have been performed to aid the structural assignment of the spectra and to explore the reaction mechanism. Activation energies for the isomerizations of the solvated structures to the inserted ones in the Au-/Au + HR reactions (R = OCH3 and OH) are predicted to be much higher than those for the Au-/Au + CH3SH reactions, supporting the experimental observation. Theoretical calculations provide the evidence that the intriguing [HAuSCH3]- product may be formed by the attachment of the electron onto the neutral HAuSCH3 species or the isomerization from the anionic [Au⋯HSCH3]- one. These findings should be helpful for understanding the feature that the thiols are able to form the staple motifs, whereas CH3OH and H2O are not.

  8. Reactions of Monomeric [1,2,4-(Me3C)3C5H2]2CeH and CO with orwithout H2:An Experimental and Computational Study

    SciTech Connect

    Werkema, Evan L.; Maron, Laurent; Eisenstein, Odile; Andersen,Richard A.

    2006-09-07

    Addition of CO to [1,2,4-(Me3C)3C5H2]2CeH, Cp'2CeH, intoluene yields the cis (Cp'2Ce)2(mu-OCHCHO), in which the cis enediolategroup bridges the two metallocene fragments. The cis enediolatequantitatively isomerizes intramolecularly to the trans-enediolate inC6D6 at 100oC over seven months. When the solvent is pentane,Cp'2Ce(OCH2)CeCp'2 forms, in which the oxomethylene group or theformaldehyde dianion bridges the two metallocene fragments. The cisenediolate is suggested to form by insertion of CO into the Ce-C bond ofCp'2Ce(OCH2)CeCp'2 generating Cp'2CeOCH2COCeCp'2. The stereochemistry ofthe cis-enediolate is determined by a 1,2-hydrogen shift in the OCH2COfragment that has the OC(H2) bond anti periplanar relative to the carbenelone pair. The bridging oxomethylene complex reacts with H2, but not withCH4, to give Cp'2CeOMe, which is also the product of the reaction betweenCp'2CeH and a mixture of CO and H2. The oxomethylene complex reacts withCO to give the cis enediolate complex. DFT calculations on C5H5 modelmetallocenes show that the reaction of Cp2CeH with CO and H2 to giveCp2CeOMe is exoergic by 50 kcal mol-1. The net reaction proceeds by aseries of elementary reactions that occur after the formyl complex,Cp2Ce(eta-2 CHO), is formed by further reaction with H2. The key pointthat emerges from the calculated potential energy surface is thebifunctional nature of the metal formyl in which the carbon atom behavesas a donor and acceptor. Replacing H2 by CH4 increases the activationenergy barrier by 17 kcal mol-1.

  9. Molecular cycloencapsulation augments solubility and improves therapeutic index of brominated noscapine in prostate cancer cells.

    PubMed

    Madan, Jitender; Baruah, Bharat; Nagaraju, Mulpuri; Abdalla, Mohamed O; Yates, Clayton; Turner, Timothy; Rangari, Vijay; Hamelberg, Donald; Aneja, Ritu

    2012-05-07

    We have previously shown that a novel microtubule-modulating noscapinoid, EM011 (9-Br-Nos), displays potent anticancer activity by inhibition of cellular proliferation and induction of apoptosis in prostate cancer cells and preclinical mice models. However, physicochemical and cellular barriers encumber the development of viable formulations for future clinical translation. To circumvent these limitations, we have synthesized EM011-cyclodextrin inclusion complexes to improve solubility and enhance therapeutic index of EM011. Phase solubility analysis indicated that EM011 formed a 1:1 stoichiometric complex with β-CD and methyl-β-CD, with a stability constant (K(c)) of 2.42 × 10(-3) M and 4.85 × 10(-3) M, respectively. Fourier transform infrared spectroscopy suggested the penetrance of either a O-CH(2) or OCH(3)-C(6)H(4)-OCH(3) moiety of EM011 in the β-CD or methyl-β-CD cavity. In addition, multifarious techniques, namely, differential scanning calorimetry, powder X-ray diffraction, scanning electron microscopy, NMR spectroscopy, and computational studies validated the cage complex of EM011 with β-CD and methyl-β-CD. Moreover, rotating frame overhauser enhancement spectroscopy showed that the H(a) proton of the OCH(3)-C(6)H(4)-OCH(3) moiety was in close proximity with H3 proton of the β-CD or methyl-β-CD cavity. Furthermore, we found that the solubility of EM011 in phosphate buffer saline (pH 7.4) was enhanced by ~11 fold and ~21 fold upon complexation with β-CD and methyl-β-CD, respectively. The enhanced dissolution of the drug CD-complexes in aqueous phase remarkably decreased their IC(50) to 28.5 μM (9-Br-Nos-β-CD) and 12.5 μM (9-Br-Nos-methyl-β-CD) in PC-3 cells compared to free EM011 (~200 μM). This is the first report to demonstrate the novel construction of cylcodextrin-based nanosupramolecular vehicles for enhanced delivery of EM011 that warrants in vivo evaluation for the superior management of prostate cancer.

  10. Molecular cycloencapsulation augments solubility and improves therapeutic index of brominated noscapine in prostate cancer cells

    PubMed Central

    Madan, Jitender; Baruah, Bharat; Nagaraju, Mulpuri; Abdalla, Mohamed O.; Yates, Clayton; Turner, Timothy; Rangari, Vijay; Hamelberg, Donald; Aneja, Ritu

    2012-01-01

    We have previously shown that a novel microtubule-modulating noscapinoid, EM011 (9-Br-Nos), displays potent anticancer activity by inhibition of cellular proliferation and induction of apoptosis in prostate cancer cells and preclinical mice models. However, physicochemical and cellular barriers encumber the development of viable formulations for future clinical translation. To circumvent these limitations, we have synthesized EM011-cyclodextrin inclusion complexes to improve solubility and enhance therapeutic index of EM011. Phase solubility analysis indicated that EM011 formed a 1:1 stoichiometric complex with β-CD and methyl-β-CD, with a stability constant (Kc) of 2.42 × 10−3 M and 4.85 × 10−3 M, respectively. Fourier transform infrared spectroscopy suggested the penetrance of either O-CH2 or OCH3-C6H4-OCH3 moiety of EM011 in the β-CD or methyl-β-CD cavity. In addition, multifarious techniques viz., differential scanning calorimetry, powder X-ray diffraction, scanning electron microscopy, NMR spectroscopy, and computational studies validated the cage complex of EM011 with β-CD and methyl-β-CD. Moreover, rotating frame overhauser enhancement spectroscopy showed that the Ha proton of OCH3-C6H4-OCH3 moiety was in close proximity with H3 proton of β-CD or methyl-β-CD cavity. Furthermore, we found that the solubility of EM011 in phosphate buffer saline (pH 7.4) was enhanced by ∼11 fold and ∼21 fold upon complexation with β-CD and methyl-β-CD, respectively. The enhanced dissolution of the drug CD-complexes in aqueous phase remarkably decreased their IC50 to 28.5 μM (9-Br-Nos-β-CD) and 12.5 μM (9-Br-Nos-methyl-β-CD) in PC-3 cells compared to free EM011 (∼200 μM). This is the first report to demonstrate the novel construction of cylcodextrin-based nanosupramolecular vehicles for enhanced delivery of EM011 that warrants in vivo evaluation for the superior management of prostate cancer. PMID:22540277

  11. Thermal decomposition of gaseous ammonium nitrate at low pressure: kinetic modeling of product formation and heterogeneous decomposition of nitric acid.

    PubMed

    Park, J; Lin, M C

    2009-12-03

    The thermal decomposition of ammonium nitrate, NH(4)NO(3) (AN), in the gas phase has been studied at 423-56 K by pyrolysis/mass spectrometry under low-pressure conditions using a Saalfeld reactor coated with boric acid. The sublimation of NH(4)NO(3) at 423 K was proposed to produce equal amounts of NH(3) and HNO(3), followed by the decomposition reaction of HNO(3), HNO(3) + M --> OH + NO(2) + M (where M = third-body and reactor surface). The absolute yields of N(2), N(2)O, H(2)O, and NH(3), which can be unambiguously measured and quantitatively calibrated under a constant pressure at 5-6.2 torr He are kinetically modeled using the detailed [H,N,O]-mechanism established earlier for the simulation of NH(3)-NO(2) (Park, J.; Lin, M. C. Technologies and Combustion for a Clean Environment. Proc. 4th Int. Conf. 1997, 34-1, 1-5) and ADN decomposition reactions (Park, J.; Chakraborty, D.; Lin, M. C. Proc. Combust. Inst. 1998, 27, 2351-2357). Since the homogeneous decomposition reaction of HNO(3) itself was found to be too slow to account for the consumption of reactants and the formation of products, we also introduced the heterogeneous decomposition of HNO(3) in our kinetic modeling. The heterogeneous decomposition rate of HNO(3), HNO(3) + (B(2)O(3)/SiO(2)) --> OH + NO(2) + (B(2)O(3)/SiO(2)), was determined by varying its rate to match the modeled result to the measured concentrations of NH(3) and H(2)O; the rate could be represented by k(2b) = 7.91 x 10(7) exp(-12 600/T) s(-1), which appears to be consistent with those reported by Johnston and co-workers (Johnston, H. S.; Foering, L.; Tao, Y.-S.; Messerly, G. H. J. Am. Chem. Soc. 1951, 73, 2319-2321) for HNO(3) decomposition on glass reactors at higher temperatures. Notably, the concentration profiles of all species measured could be satisfactorily predicted by the existing [H,N,O]-mechanism with the heterogeneous initiation process.

  12. Thermal Decomposition of Gaseous Ammonium Nitrate at Low Pressure: Kinetic Modeling of Product Formation and Heterogeneous Decomposition of Nitric Acid

    NASA Astrophysics Data System (ADS)

    Park, J.; Lin, M. C.

    2009-10-01

    The thermal decomposition of ammonium nitrate, NH4NO3 (AN), in the gas phase has been studied at 423-56 K by pyrolysis/mass spectrometry under low-pressure conditions using a Saalfeld reactor coated with boric acid. The sublimation of NH4NO3 at 423 K was proposed to produce equal amounts of NH3 and HNO3, followed by the decomposition reaction of HNO3, HNO3 + M → OH + NO2 + M (where M = third-body and reactor surface). The absolute yields of N2, N2O, H2O, and NH3, which can be unambiguously measured and quantitatively calibrated under a constant pressure at 5-6.2 torr He are kinetically modeled using the detailed [H,N,O]-mechanism established earlier for the simulation of NH3-NO2 (Park, J.; Lin, M. C. Technologies and Combustion for a Clean Environment. Proc. 4th Int. Conf. 1997, 34-1, 1-5) and ADN decomposition reactions (Park, J.; Chakraborty, D.; Lin, M. C. Proc. Combust. Inst. 1998, 27, 2351-2357). Since the homogeneous decomposition reaction of HNO3 itself was found to be too slow to account for the consumption of reactants and the formation of products, we also introduced the heterogeneous decomposition of HNO3 in our kinetic modeling. The heterogeneous decomposition rate of HNO3, HNO3 + (B2O3/SiO2) → OH + NO2 + (B2O3/SiO2), was determined by varying its rate to match the modeled result to the measured concentrations of NH3 and H2O; the rate could be represented by k2b = 7.91 × 107 exp(-12 600/T) s-1, which appears to be consistent with those reported by Johnston and co-workers (Johnston, H. S.; Foering, L.; Tao, Y.-S.; Messerly, G. H. J. Am. Chem. Soc. 1951, 73, 2319-2321) for HNO3 decomposition on glass reactors at higher temperatures. Notably, the concentration profiles of all species measured could be satisfactorily predicted by the existing [H,N,O]-mechanism with the heterogeneous initiation process.

  13. Magnesium Diboride Current Leads

    NASA Technical Reports Server (NTRS)

    Panek, John

    2010-01-01

    A recently discovered superconductor, magnesium diboride (MgB2), can be used to fabricate conducting leads used in cryogenic applications. Dis covered to be superconducting in 2001, MgB2 has the advantage of remaining superconducting at higher temperatures than the previously used material, NbTi. The purpose of these leads is to provide 2 A of electricity to motors located in a 1.3 K environment. The providing environment is a relatively warm 17 K. Requirements for these leads are to survive temperature fluctuations in the 5 K and 11 K heat sinks, and not conduct excessive heat into the 1.3 K environment. Test data showed that each lead in the assembly could conduct 5 A at 4 K, which, when scaled to 17 K, still provided more than the required 2 A. The lead assembly consists of 12 steelclad MgB2 wires, a tensioned Kevlar support, a thermal heat sink interface at 4 K, and base plates. The wires are soldered to heavy copper leads at the 17 K end, and to thin copper-clad NbTi leads at the 1.3 K end. The leads were designed, fabricated, and tested at the Forschungszentrum Karlsruhe - Institut foer Technische Physik before inclusion in Goddard's XRS (X-Ray Spectrometer) instrument onboard the Astro-E2 spacecraft. A key factor is that MgB2 remains superconducting up to 30 K, which means that it does not introduce joule heating as a resistive wire would. Because the required temperature ranges are 1.3-17 K, this provides a large margin of safety. Previous designs lost superconductivity at around 8 K. The disadvantage to MgB2 is that it is a brittle ceramic, and making thin wires from it is challenging. The solution was to encase the leads in thin steel tubes for strength. Previous designs were so brittle as to risk instrument survival. MgB2 leads can be used in any cryogenic application where small currents need to be conducted at below 30 K. Because previous designs would superconduct only at up to 8 K, this new design would be ideal for the 8-30 K range.

  14. Formation of ethylene glycol and other complex organic molecules in star-forming regions

    NASA Astrophysics Data System (ADS)

    Rivilla, V. M.; Beltrán, M. T.; Cesaroni, R.; Fontani, F.; Codella, C.; Zhang, Q.

    2017-02-01

    Context. The detection of complex organic molecules related with prebiotic chemistry in star-forming regions allows us to investigate how the basic building blocks of life are formed. Aims: Ethylene glycol (CH2OH)2 is the simplest sugar alcohol and the reduced alcohol of the simplest sugar glycoladehyde (CH2OHCHO). We study the molecular abundance and spatial distribution of (CH2OH)2, CH2OHCHO and other chemically related complex organic species (CH3OCHO, CH3OCH3, and C2H5OH) towards the chemically rich massive star-forming region G31.41+0.31. Methods: We analyzed multiple single-dish (Green Bank Telescope and IRAM 30 m) and interferometric (Submillimeter Array) spectra towards G31.41+0.31, covering a range of frequencies from 45 to 258 GHz. We fitted the observed spectra with a local thermodynamic equilibrium (LTE) synthetic spectra, and obtained excitation temperatures and column densities. We compared our findings in G31.41+0.31 with the results found in other environments, including low- and high-mass star-forming regions, quiescent clouds and comets. Results: We report for the first time the presence of the aGg' conformer of (CH2OH)2 towards G31.41+0.31, detecting more than 30 unblended lines. We also detected multiple transitions of other complex organic molecules such as CH2OHCHO, CH3OCHO, CH3OCH3, and C2H5OH. The high angular resolution images show that the (CH2OH)2 emission is very compact, peaking towards the maximum of the 1.3 mm continuum. These observations suggest that low abundance complex organic molecules, like (CH2OH)2 or CH2OHCHO, are good probes of the gas located closer to the forming stars. Our analysis confirms that (CH2OH)2 is more abundant than CH2OHCHO in G31.41+0.31, as previously observed in other interstellar regions. Comparing different star-forming regions we find evidence of an increase of the (CH2OH)2/CH2OHCHO abundance ratio with the luminosity of the source. The CH3OCH3/CH3OCHO and (CH2OH)2/C2H5OH ratios are nearly constant with

  15. On the structural and electronic considerations concerning the reactivity of metal-metal multiple bonds

    NASA Astrophysics Data System (ADS)

    Glasgow, Katherine Campbell

    2000-10-01

    The previously known compound W2(OCH2tBu) 6(py)2 is crystallographically characterized. Its solid state structure is described and compared with other M2(OR)6L 2 complexes. Upon treatment with isoprene, the complex W2(OCH 2tBu)6(py)(mu-isoprene) forms. The solid state structure is disordered with respect to the orientation of the diene; two different configurations are seen in the crystal structure. These two isomers are in equilibrium in solution and are visible by 1H NMR spectroscopy. Multidimensional NMR experiments are used to assign the structures of the two isomers in solution. Through the use of spin magnetization transfer, it has been determined that the two isomers interconvert through the loss of isoprene. The DeltaH° and DeltaS° values for the equilibrium are determined. The starting material W2(OCH2tBu) 6(py)2 had been previously determined to be an olefin hydrogenation catalyst. It has been determined that cyclic olefins are hydrogenated in a cis manner, and a kinetic isotope effect of 1.7 has been measured. It has been determined that olefins which form isolable adducts with W 2(OCH2tBu)6(py)2, such as isoprene, undergo hydrogenation at approximately the same rate as olefins which do not show evidence of adduct formation. The complex W2(OCH2tBu)6(py) 2had been found to couple aldehydes and ketones stoichiometrically to give olefins. The reaction was found to proceed in a stepwise manner through the alkylidene intermediate W2(OCH2tBu) 6(py)(O)(mu-CHR), allowing the selective cross coupling of aldehydes and ketones. More studies have been undertaken to help determine the scope of the reaction. Competition experiments have been performed to determine reaction preferences. Unsaturated and functionalized aldehydes have been studied to determine the tolerance of the reaction to certain chemical groups. The role of pyridine in this reaction has been studied, especially concerning its reactivity with the alkylidene intermediate. The dimetal tetracarboxylate

  16. Hydrogen-bonding Interactions between Apigenin and Ethanol/Water: A Theoretical Study

    NASA Astrophysics Data System (ADS)

    Zheng, Yan-Zhen; Zhou, Yu; Liang, Qin; Chen, Da-Fu; Guo, Rui; Lai, Rong-Cai

    2016-10-01

    In this work, hydrogen-bonding interactions between apigenin and water/ethanol were investigated from a theoretical perspective using quantum chemical calculations. Two conformations of apigenin molecule were considered in this work. The following results were found. (1) For apigenin monomer, the molecular structure is non-planar, and all of the hydrogen and oxygen atoms can be hydrogen-bonding sites. (2) Eight and seven optimized geometries are obtained for apigenin (I)–H2O/CH3CH2OH and apigenin (II)–H2O/CH3CH2OH complexes, respectively. In apigenin, excluding the aromatic hydrogen atoms in the phenyl substituent, all other hydrogen atoms and the oxygen atoms form hydrogen-bonds with H2O and CH3CH2OH. (3) In apigenin–H2O/CH3CH2OH complexes, the electron density and the E(2) in the related localized anti-bonding orbital are increased upon hydrogen-bond formation. These are the cause of the elongation and red-shift of the X‑H bond. The sum of the charge change transfers from the hydrogen-bond acceptor to donor. The stronger interaction makes the charge change more intense than in the less stable structures. (4) Most of the hydrogen-bonds in the complexes are electrostatic in nature. However, the C4‑O5···H, C9‑O4···H and C13‑O2···H hydrogen-bonds have some degree of covalent character. Furthermore, the hydroxyl groups of the apigenin molecule are the preferred hydrogen-bonding sites.

  17. Hydrogen-bonding Interactions between Apigenin and Ethanol/Water: A Theoretical Study

    PubMed Central

    Zheng, Yan-Zhen; Zhou, Yu; Liang, Qin; Chen, Da-Fu; Guo, Rui; Lai, Rong-Cai

    2016-01-01

    In this work, hydrogen-bonding interactions between apigenin and water/ethanol were investigated from a theoretical perspective using quantum chemical calculations. Two conformations of apigenin molecule were considered in this work. The following results were found. (1) For apigenin monomer, the molecular structure is non-planar, and all of the hydrogen and oxygen atoms can be hydrogen-bonding sites. (2) Eight and seven optimized geometries are obtained for apigenin (I)–H2O/CH3CH2OH and apigenin (II)–H2O/CH3CH2OH complexes, respectively. In apigenin, excluding the aromatic hydrogen atoms in the phenyl substituent, all other hydrogen atoms and the oxygen atoms form hydrogen-bonds with H2O and CH3CH2OH. (3) In apigenin–H2O/CH3CH2OH complexes, the electron density and the E(2) in the related localized anti-bonding orbital are increased upon hydrogen-bond formation. These are the cause of the elongation and red-shift of the X−H bond. The sum of the charge change transfers from the hydrogen-bond acceptor to donor. The stronger interaction makes the charge change more intense than in the less stable structures. (4) Most of the hydrogen-bonds in the complexes are electrostatic in nature. However, the C4−O5···H, C9−O4···H and C13−O2···H hydrogen-bonds have some degree of covalent character. Furthermore, the hydroxyl groups of the apigenin molecule are the preferred hydrogen-bonding sites. PMID:27698481

  18. Synthesis, characteristic and theoretical investigation of the structure, electronic properties and second-order nonlinearity of salicylaldehyde Schiff base and their derivatives

    NASA Astrophysics Data System (ADS)

    Tang, Guo-Dong; Zhao, Jian-Ying; Li, Rong-Qing; Yuan-Cao; Zhang, Zai-Chao

    2011-01-01

    A series of asymmetric donor-acceptor substituted salen-type Schiff-bases have been synthesized and their structures, electronic properties and second order nonlinearities were investigated by DFT methods. In order to verify the stable of these Schiff-base derivates, the IR spectrum of these Schiff-base derivates were calculated, the result showed that these compounds are stable. The results of TD-DFT calculation indicate that the derivatives with the electron-donating group (CH 3, OCH 3 or N(C 2H 5) 2) have a red shift absorption compared to derivatives with the electron-withdrawing group (NO 2). The analysis of MOS indicates that the CN group has contribution to the LUMO orbital while the groups of OCH 3, N(C 2H 5) 2 and NO 2 have contribution to the HOMO orbital. OCH 3, N(C 2H 5) 2 as electron rich groups, made the derivates have a larger first static hyperpolarizability. However, the compound (II) with a NO 2 substituent, also has a large first static hyperpolarizability. This is probably because of the special transition model, namely the values of two oscillator strength f ( fHOMO-1-LUMO = 0.405, fHOMO-LUMO = 0.321) are almost equal. In order to understand the influence of the energy gap (Δ E) between the HOMO and the LUMO orbitals on the first static hyperpolarizability, we calculated the energy gap (Δ E) of all Schiff-base compounds. The results show that the smaller the HOMO-LUMO energy gap is, the larger the first static hyperpolarizability is.

  19. Synthesis of a TREN in which the aryl substituents are part of a 45 atom macrocycle.

    PubMed

    Cain, Matthew F; Forrest, William P; Peryshkov, Dmitry V; Schrock, Richard R; Müller, Peter

    2013-10-16

    A substituted TREN has been prepared in which the aryl groups in (ArylNHCH2CH2)3N are substituted at the 3- and 5-positions with a total of six OCH2(CH2)nCH═CH2 groups (n = 1, 2, 3). Molybdenum nitride complexes, [(ArylNCH2CH2)3N]Mo(N), have been isolated as adducts that contain B(C6F5)3 bound to the nitride. Two of these [(ArylNCH2CH2)3N]Mo(NB(C6F5)3) complexes (n = 1 and 3) were crystallographically characterized. After removal of the borane from [(ArylNCH2CH2)3N]Mo(NB(C6F5)3) with PMe3, ring-closing olefin metathesis (RCM) was employed to join the aryl rings with OCH2(CH2)nCH═CH(CH2)nCH2O links (n = 1-3) between them. RCM worked best with a W(O)(CHCMe3)(Me2Pyr)(OHMT)(PMe2Ph) catalyst (OHMT = hexamethylterphenoxide, Me2Pyr = 2,5-dimethylpyrrolide) and n = 3. The macrocyclic ligand was removed from the metal through hydrolysis and isolated in 70-75% yields relative to the borane adducts. Crystallographic characterization showed that the macrocyclic TREN ligand in which n = 3 contains three cis double bonds. Hydrogenation produced a TREN in which the three links are saturated, i.e., O(CH2)10O.

  20. An OEGylated thiol monolayer for the tethering of liposomes and the study of liposome interactions.

    PubMed

    Briand, Elisabeth; Humblot, Vincent; Pradier, Claire-Marie; Kasemo, Bengt; Svedhem, Sofia

    2010-06-15

    The aim of the present work is to develop a protocol for the specific immobilization of liposomes, via tethers, onto functionalized gold surfaces, and in addition to give one example for such a surface architecture. All surface functionalization steps are charcerized and controlled. First, mixed thiolate self-assembled monolayers (SAMs) prepared from COOH- and OCH(3)-terminated oligo(ethylene glycol) (OEG) alkane thiols were characterized by polarization modulation reflection absorption infrared spectroscopy (PM-RAIRS) and by X-ray photoemission spectroscopy (XPS). The composition of the mixed SAMs was found to be close to that of the thiol solution. Next, grafting of biotin conjugated with an NH(2)-terminated OEG spacer (biotin-OEG-NH(2)) to the COOH groups via conventional amine coupling was optimized with respect to the COOH/OCH(3) ratio of the SAM. The grafting of biotin-OEG-NH(2) was assessed by monitoring the binding of neutravidin and albumin to the biotinylated surfaces using quartz crystal microbalance with dissipation monitoring (QCM-D), as well as by PM-RAIRS. It was shown that a COOH/OCH(3) ratio of around 0.3 was sufficient to saturate the SAMs with neutravidin. Finally, tethering of liposomes onto the neutravidin-terminated SAMs, was achieved. As an application example, of a close packed layer of tethered liposomes was exposed to the membrane-penetrating peptide melittin. As monitored by QCM-D, the liposomes fused when interacting with the peptide and ruptured into an extended, supported lipid bilayer over the whole surface. In summary, the described surface modification has potential for the development of assays requiring tethered intact liposomes, or tethered planar bilayers. Such surface architectures are especially important for the study of transmembrane proteins and peptides.

  1. Slip Rate Determination of Thrusts Along the Edge of NE Tibet From in situ-Produced Cosmogenic Nuclides

    NASA Astrophysics Data System (ADS)

    Hetzel, R.; Niedermann, S.; Tao, M.; Ivy-Ochs, S.; Stokes, S.; Strecker, M. R.; Kubik, P. W.

    2005-12-01

    The Qilian Shan forms a seismically active fold-and-thrust-belt along the NE margin of the Tibetan Plateau that evolved during the Neogene-Quaternary and continues to advance north-northeastward (Meyer et al., 1998; Tapponnier et al., 2001). Active thrust faults transecting Late Pleistocene alluvial fan deposits form spectacular fault scarps that are locally incised by rivers which form flights of terraces. By combining structural investigations, satellite imagery, topographic profiling, surface exposure, and luminescence dating we have determined slip rates for several thrust faults (Hetzel et al. 2002, 2004a,b). Our results are consistent with geologic and GPS constraints, which suggest that NNE-directed shortening across the northeastern Tibetan Plateau is distributed on several active faults with a total shortening rate of about 4 to 10 mm/yr. References Hetzel, R., S. Niedermann, M. Tao, P.W. Kubik, S. Ivy-Ochs, B. Gao, M.R. Strecker (2002a), Nature, 417, 428-432. Hetzel, R., M. Tao, S. Niedermann, M.R. Strecker, S. Ivy-Ochs, P.W. Kubik, B. Gao (2004a), Terra Nova 16, 157-162. Hetzel R., M. Tao, S. Stokes, S. Niedermann, S. Ivy-Ochs, G. Bo, M.R. Strecker, P.W. Kubik (2004b), Tectonics 23, TC6006, doi:10.1029/2004TC001653. Meyer, B., P. Tapponnier, L. Bourjot, F. Metivier, Y. Gaudemer, G. Peltzer, G. Shunmin, C. Zhitai (1998), Geophys. J. Int., 135, 1-47. Tapponnier, P., Z. Xu, F. Roger, B. Meyer, N. Arnaud, G. Wittlinger, J. Yang (2001), Science, 294, 1671-1677.

  2. Multiheteromacrocycles that Complex Metal Ions. Second Progress Report, 1 May 1975 -- 30 April 1976

    DOE R&D Accomplishments Database

    Cram, D. J.

    1976-01-15

    Objective is to develop cyclic and polycyclic host organic compounds to complex and lipophilize metal ions. Macrorings were synthesized: (OCH{sub 2} CH{sub 2} O CH{sub 2}COCH{sub 2} COCH{sub 2}){sub 2} and (OCH{sub 2} CH{sub 2} O CH{sub 2} COCH{sub 2} COCH{sub 2}){sub 3}. The smaller ring complexes divalent metals 10{sup 1+9} times better than the open-chain model CH{sub 3} O CH{sub 2} CO CH{sub 2} COCH{sub 2} O CH{sub 3}, and the order in which metal ions are complexed is Cu{sup 2+}, UO{sub 2}{sup 2+} greater than Ni{sup 2+} greater than Fe{sup 2+}, Co{sup 2+}, Zn{sup 2+}, Cd{sup 2+} greater than Mn{sup 2+}. The UO{sub 2}{sup 2+} and Cu{sup 2+} complexes were isolated and characterized. The larger ring complexes trivalent metals 10{sup 0.9-1.7} times better than the open- chain model compound, and the order is La{sup 3+}, Ce{sup 3+} greater than Cr{sup 3+}. Five other macrocycles were also synthesized, and their binding constants with Na, K, NH{sub 4}, and Cs picrates were measured. Six compounds containing one macroring and two inward-pointing ArOH or ArOCH{sub 3} groups were also prepared and tested for binding of Li, Na, K, Rb, and NH{sub 4} picrates. Racemic compounds containing two binaphthyls and its sulfur analog were prepared. Cage-shaped multiheteromacrocycles containing ten O ligand sites or four S and six O ligand sites were prepared and the binding capability of the first compound for picrates studied. Two ring systems with phosphonate ester groups were also prepared. (DLC)

  3. CNN pincer ruthenium catalysts for hydrogenation and transfer hydrogenation of ketones: experimental and computational studies.

    PubMed

    Baratta, Walter; Baldino, Salvatore; Calhorda, Maria José; Costa, Paulo J; Esposito, Gennaro; Herdtweck, Eberhardt; Magnolia, Santo; Mealli, Carlo; Messaoudi, Abdelatif; Mason, Sax A; Veiros, Luis F

    2014-10-13

    Reaction of [RuCl(CNN)(dppb)] (1-Cl) (HCNN=2-aminomethyl-6-(4-methylphenyl)pyridine; dppb=Ph2 P(CH2 )4 PPh2 ) with NaOCH2 CF3 leads to the amine-alkoxide [Ru(CNN)(OCH2 CF3 )(dppb)] (1-OCH2 CF3 ), whose neutron diffraction study reveals a short RuO⋅⋅⋅HN bond length. Treatment of 1-Cl with NaOEt and EtOH affords the alkoxide [Ru(CNN)(OEt)(dppb)]⋅(EtOH)n (1-OEt⋅n EtOH), which equilibrates with the hydride [RuH(CNN)(dppb)] (1-H) and acetaldehyde. Compound 1-OEt⋅n EtOH reacts reversibly with H2 leading to 1-H and EtOH through dihydrogen splitting. NMR spectroscopic studies on 1-OEt⋅n EtOH and 1-H reveal hydrogen bond interactions and exchange processes. The chloride 1-Cl catalyzes the hydrogenation (5 atm of H2 ) of ketones to alcohols (turnover frequency (TOF) up to 6.5×10(4) h(-1) , 40 °C). DFT calculations were performed on the reaction of [RuH(CNN')(dmpb)] (2-H) (HCNN'=2-aminomethyl-6-(phenyl)pyridine; dmpb=Me2 P(CH2 )4 PMe2 ) with acetone and with one molecule of 2-propanol, in alcohol, with the alkoxide complex being the most stable species. In the first step, the Ru-hydride transfers one hydrogen atom to the carbon of the ketone, whereas the second hydrogen transfer from NH2 is mediated by the alcohol and leads to the key "amide" intermediate. Regeneration of the hydride complex may occur by reaction with 2-propanol or with H2 ; both pathways have low barriers and are alcohol assisted.

  4. Synthesis, characteristic and theoretical investigation of the structure, electronic properties and second-order nonlinearity of salicylaldehyde Schiff base and their derivatives.

    PubMed

    Tang, Guo-Dong; Zhao, Jian-Ying; Li, Rong-Qing; Yuan-Cao; Zhang, Zai-Chao

    2011-01-01

    A series of asymmetric donor-acceptor substituted salen-type Schiff-bases have been synthesized and their structures, electronic properties and second order nonlinearities were investigated by DFT methods. In order to verify the stable of these Schiff-base derivates, the IR spectrum of these Schiff-base derivates were calculated, the result showed that these compounds are stable. The results of TD-DFT calculation indicate that the derivatives with the electron-donating group (CH3, OCH3 or N(C2H5)2) have a red shift absorption compared to derivatives with the electron-withdrawing group (NO2). The analysis of MOS indicates that the CN group has contribution to the LUMO orbital while the groups of OCH3, N(C2H5)2 and NO2 have contribution to the HOMO orbital. OCH3, N(C2H5)2 as electron rich groups, made the derivates have a larger first static hyperpolarizability. However, the compound (II) with a NO2 substituent, also has a large first static hyperpolarizability. This is probably because of the special transition model, namely the values of two oscillator strength f (fHOMO-1-LUMO=0.405, fHOMO-LUMO=0.321) are almost equal. In order to understand the influence of the energy gap (ΔE) between the HOMO and the LUMO orbitals on the first static hyperpolarizability, we calculated the energy gap (ΔE) of all Schiff-base compounds. The results show that the smaller the HOMO-LUMO energy gap is, the larger the first static hyperpolarizability is.

  5. Searching for trans ethyl methyl ether in Orion KL★,★★

    PubMed Central

    Tercero, B.; Cernicharo, J.; López, A.; Brouillet, N.; Kolesniková, L.; Motiyenko, R. A.; Margulès, L.; Alonso, J. L.; Guillemin, J.-C.

    2015-01-01

    We report on the tentative detection of trans ethyl methyl ether (tEME), t-CH3CH2OCH3, through the identification of a large number of rotational lines from each one of the spin states of the molecule towards Orion KL. We also search for gauche-trans-n-propanol, Gt-n-CH3CH2CH2OH, an isomer of tEME in the same source. We have identified lines of both species in the IRAM 30 m line survey and in the ALMA Science Verification data. We have obtained ALMA maps to establish the spatial distribution of these species. Whereas tEME mainly arises from the compact ridge component of Orion, Gt-n-propanol appears at the emission peak of ethanol (south hot core). The derived column densities of these species at the location of their emission peaks are ≤(4.0 ± 0.8) × 1015 cm−2 and ≤(1.0 ± 0.2)× 1015 cm−2 for tEME and Gt-n-propanol, respectively. The rotational temperature is ~100 K for both molecules. We also provide maps of CH3OCOH, CH3CH2OCOH, CH3OCH3, CH3OH, and CH3CH2OH to compare the distribution of these organic saturated O-bearing species containing methyl and ethyl groups in this region. Abundance ratios of related species and upper limits to the abundances of non-detected ethers are provided. We derive an abundance ratio N(CH3OCH3)/N(tEME) ≥ 150 in the compact ridge of Orion. PMID:26869726

  6. Thorium-mediated ring-opening of tetrahydrofuran and the development of a new thorium starting material: preparation and chemistry of ThI4(DME)2.

    PubMed

    Travia, Nicholas E; Monreal, Marisa J; Scott, Brian L; Kiplinger, Jaqueline L

    2012-12-28

    The thorium(IV) tetraiodide complex ThI(4)(DME)(2) (3) (DME = 1,2-dimethoxyethane) has been prepared in high yield by reacting the corresponding chloride complex ThCl(4)(DME)(2) with an excess of trimethylsilyl iodide (Me(3)SiI) in toluene. This new route avoids the use of thorium metal as a reagent. ThI(4)(DME)(2) (3) exhibits excellent thermal stability compared to ThI(4)(THF)(4) (1), which undergoes rapid ring-opening of THF at ambient temperature to yield the iodobutoxide complex ThI(3)[O(CH(2))(4)I](THF)(3) (2). Subsequent ligand-exchange between 2 and DME affords ThI(3)[O(CH(2))(4)I](DME)(2) (11), which can be converted to 3 with Me(3)SiI. Salt metathesis between 2 and K(L(Me)) (L(Me) = (2,6-(i)Pr(2)C(6)H(3))NC(Me)CHC(Me)N(2,6-(i)Pr(2)C(6)H(3))) cleanly gives (L(Me))ThI(2)[O(CH(2))(4)I](THF) (10), which is a rare example of a thorium β-diketiminate complex. Complexes 2, 10, and 11 represent the first reported examples of THF ring-opening mediated by thorium. The synthetic utility of ThI(4)(DME)(2) (3) is demonstrated by preparation of thorium(IV) alkoxide, amide, and organometallic compounds.

  7. Rate constants for the reaction of OH radicals with n-propyl, n-butyl, iso-butyl and tert-butyl vinyl ethers

    NASA Astrophysics Data System (ADS)

    Thiault, G.; Mellouki, A.

    Rate constants for the reaction of OH radicals with n-propyl vinyl ether (PVE, CH 3CH 2CH 2OCH dbnd CH 2), n-butyl vinyl ether (BVE, CH 3CH 2CH 2CH 2OCH dbnd CH 2), iso-butyl vinyl ether (IBVE, (CH 3) 2CHCH 2OCH dbnd CH 2) and tert-butyl vinyl ether (TBVE, (CH 3) 3COCH dbnd CH 2), have been measured in the temperature and pressure ranges 232-373 K and 30-300 Torr using the pulsed laser photolysis-laser-induced fluorescence method, and at 298 K and 760 Torr using the relative method. The obtained results are k1=(9.3±0.6)×10 -12 exp[(708±20)/ T], k2=(1.5±0.2)×10 -11 exp[(572±42)/ T], k3=(1.6±0.1)×10 -11 exp[(567±20)/ T], k4=(1.7±0.2)×10 -11 exp[(549±25)/ T] cm 3 molecule -1 s -1. The values at 298 K are k1=(1.0±0.1)×10 -10, k2=(1.0±0.1)×10 -10, k3=(1.1±0.1)×10 -10, k4=(1.1±0.1)×10 -10 cm 3 molecule -1 s -1. The deduced tropospheric lifetimes of these ethers for reaction with OH are of the order of 1 h and they are comparable to those for reaction with ozone.

  8. Searching for trans ethyl methyl ether in Orion KL(.)

    PubMed

    Tercero, B; Cernicharo, J; López, A; Brouillet, N; Kolesniková, L; Motiyenko, R A; Margulès, L; Alonso, J L; Guillemin, J-C

    2015-10-01

    We report on the tentative detection of trans ethyl methyl ether (tEME), t-CH3CH2OCH3, through the identification of a large number of rotational lines from each one of the spin states of the molecule towards Orion KL. We also search for gauche-trans-n-propanol, Gt-n-CH3CH2CH2OH, an isomer of tEME in the same source. We have identified lines of both species in the IRAM 30 m line survey and in the ALMA Science Verification data. We have obtained ALMA maps to establish the spatial distribution of these species. Whereas tEME mainly arises from the compact ridge component of Orion, Gt-n-propanol appears at the emission peak of ethanol (south hot core). The derived column densities of these species at the location of their emission peaks are ≤(4.0 ± 0.8) × 10(15) cm(-2) and ≤(1.0 ± 0.2)× 10(15) cm(-2) for tEME and Gt-n-propanol, respectively. The rotational temperature is ~100 K for both molecules. We also provide maps of CH3OCOH, CH3CH2OCOH, CH3OCH3, CH3OH, and CH3CH2OH to compare the distribution of these organic saturated O-bearing species containing methyl and ethyl groups in this region. Abundance ratios of related species and upper limits to the abundances of non-detected ethers are provided. We derive an abundance ratio N(CH3OCH3)/N(tEME) ≥ 150 in the compact ridge of Orion.

  9. Kinetics of the degradation of sulfur mustard on ambient and moist concrete.

    PubMed

    Brevett, Carol A S; Sumpter, Kenneth B; Nickol, Robert G

    2009-02-15

    The rate of degradation of the chemical warfare agent sulfur mustard, bis(2-chloroethyl) sulfide, was measured on ambient and moist concrete using (13)C Solid State Magic Angle Spinning Nuclear Magnetic Resonance (SSMAS NMR). Three samples of concrete made by the same formulation, but differing in age and alkalinity were used. The sulfur mustard eventually degraded to thiodiglycol and 1,4-oxathiane via the intermediate sulfonium ions CH-TG, H-TG, H-2TG and O(CH(2)CH(2))(2)S(+)CH(2)CH(2)OH on all of the concrete samples, and in addition formed 8-31% vinyl moieties on the newer, more alkaline concrete samples. This is the first observation of the formation of O(CH(2)CH(2))(2)S(+)CH(2)CH(2)OH on a solid substrate. The addition of 2-chloroethanol to concrete on which mustard had fully degraded to thiodiglycol and 1,4-oxathiane resulted in the formation of O(CH(2)CH(2))(2)S(+)CH(2)CH(2)OH, thus demonstrating the reversibility of sulfur mustard degradation pathways. The sulfur mustard degradation half-lives on ambient concrete at 22 degrees C ranged from 3.5 to 54 weeks. When the substrates were moistened, the degradation half-lives at 22 degrees C ranged from 75 to 350h. The degradation of sulfur mustard occurred more quickly at elevated temperatures and with added water. The non-volatile toxic sulfonium ions persisted for months to years on concrete at 22 degrees C and weeks to months on concrete at 35 degrees C, before decomposing to the relatively non-toxic compounds thiodiglycol and 1,4-oxathiane.

  10. Probe electrospray ionization (PESI) mass spectrometry with discontinuous atmospheric pressure interface (DAPI).

    PubMed

    Hiraoka, Kenzo; Usmanov, Dilshadbek T; Chen, Lee Chuin; Ninomiya, Satoshi; Mandal, Mridul K; Saha, Subhrakanti

    2015-01-01

    Probe electrospray ionization (PESI) using a 0.2 mm outside diameter titanium wire was performed and the generated ions were introduced into the mass spectrometer via a discontinuous atmospheric pressure interface using a pinch valve. Time-lapse PESI mass spectra were acquired by gradually increasing delay time for the pinch valve opening with respect to the start of each electrospray event when a high voltage was applied. The opening time of the pinch valve was 20 ms. Time-resolved PESI mass spectra showed marked differences for 10 mM NaCl, 10(-5) M gramicidin S and insulin in H(2)O/CH(3)OH/CH(3)COOH/CH(3)COONH(4) (65/35/1) with and without the addition of 10 mM CH(3)COONH(4). This was ascribed to the pH change of the liquid attached to the needle caused by electrochemical reactions taking place at the interface between the metal probe and the solution. NaCl cluster ions appeared only after the depletion of analytes. For the mixed solution of 10(-5) M cytochrome c, insulin, and gramicidin S in H(2)O/CH(3)OH/CH(3)COOH (65/35/1), a sequential appearance of analyte ions in the order of cytochrome c→insulin→gramicidin S was observed. The present technique was applied to three narcotic samples; methamphetamine, morphine and codeine. Limits of detection for these compounds were 10 ppb in H(2)O/CH(3)OH (1/1) for the single sampling with a pinch valve opening time of 200 ms.

  11. Formation of polyhydroxyalkanoate in aerobic anoxygenic phototrophic bacteria and its relationship to carbon source and light availability.

    PubMed

    Xiao, Na; Jiao, Nianzhi

    2011-11-01

    Aerobic anoxygenic phototrophic bacteria (AAPB) are unique players in carbon cycling in the ocean. Cellular carbon storage is an important mechanism regulating the nutrition status of AAPB but is not yet well understood. In this paper, six AAPB species (Dinoroseobacter sp. JL1447, Roseobacter denitrificans OCh 114, Roseobacter litoralis OCh 149, Dinoroseobacter shibae DFL 12(T), Labrenzia alexandrii DFL 11(T), and Erythrobacter longus DSMZ 6997) were examined, and all of them demonstrated the ability to form the carbon polymer polyhydroxyalkanoate (PHA) in the cell. The PHA in Dinoroseobacter sp. JL1447 was identified as poly-beta-hydroxybutyrate (PHB) according to evidence from Fourier transform infrared spectroscopy, differential scanning calorimetry, and (1)H nuclear magnetic resonance spectroscopy examinations. Carbon sources turned out to be critical for PHA production in AAPB. Among the eight media tested with Dinoroseobacter sp. JL1447, sodium acetate, giving a PHA production rate of 72%, was the most productive carbon source, followed by glucose, with a 68% PHA production rate. Such PHA production rates are among the highest recorded for all bacteria. The C/N ratio of substrates was verified by the experiments as another key factor in PHA production. In the case of R. denitrificans OCh 114, PHA was not detected when the organism was cultured at C/N ratios of <2 but became apparent at C/N ratios of >3. Light is also important for the formation of PHA in AAPB. In the case of Dinoroseobacter sp. JL1447, up to a one-quarter increase in PHB production was observed when the culture underwent growth in a light-dark cycle compared to growth completely in the dark.

  12. Surface characterization of biocidal polyurethane modifiers having poly(3,3-substituted)oxetane soft blocks with alkylammonium side chains.

    PubMed

    Kurt, Pinar; Gamble, Lara J; Wynne, Kenneth J

    2008-06-03

    This paper focuses on surface characterization of P[ AB] copolyoxetane soft block polyurethanes having either fluorous (3FOx, -CH2OCH 2CF3) or PEG-like (ME2Ox, -CH2(OCH2CH2) 2OCH3), A side chains and alkylammonium, B side chains. Physical surface characterization data were analyzed in light of the previously observed order of antimicrobial effectiveness for a set of four surface modifiers. Ample physical evidence for surface concentration of fluorous 2 wt % P[ AB]-polyurethane modifiers was obtained from XPS, contact angles, ATR-IR spectroscopy, and TM-AFM. In TM-AFM phase imaging, the most effective biocidal surface modifier, 2 wt % HMDI-BD(30)/P[(3FOx)(C12)-0.89:0.11]-PU, showed a nanoscale phase-separated structure consisting of 200 nm domains with background features about 10 times smaller. Despite similar surface characterization data, the 2 wt % fluorous C6 analog ranked third in contact biocidal effectiveness. Physical evidence for surface concentration of 2 wt % P[(ME2Ox)(C12)-0.86:0.14]-PU was modest, considering that antimicrobial effectiveness was second only to 2 wt % HMDI-BD(30)/P[(3FOx)(C12)-0.89:0.11]-PU. In this set of surface modifiers, nanoscale morphology is largely driven by the fluorous component, whereas antimicrobial effectiveness is more strongly influenced by alkylammonium chain length. The effect of alkylammonium side chain length on surface concentration and antimicrobial behavior is more pronounced for ME2Ox polyurethanes compared to the 3FOx analogs.

  13. Polyelectrolyte complex/PVA membranes for diffusion dialysis.

    PubMed

    Wang, Cong; Wu, Cuiming; Wu, Yonghui; Gu, Jingjing; Xu, Tongwen

    2013-10-15

    Polyelectrolyte complexes (PECs)/polyvinyl alcohol (PVA) membranes are prepared from PVA, anion exchange and cation exchange multisilicon copolymers, which contain plenty of functional groups of OH, N(+)(CH3)3/Si(OCH3)3, and SO3Na/Si(OCH3)3, respectively. The OH and Si(OCH3)3 groups can undertake sol-gel reaction to form crosslinking structure, while the N(+)(CH3)3 and SO3Na groups can be combined through electrostatic interaction. The PECs/PVA membranes exhibit improved thermal stability, swelling resistance and flexibility as compared with single anion or cation exchange hybrid membranes. The PECs/PVA membranes have the water uptakes (WR) of 25.3-70.4%, initial decomposition temperatures (IDTs) of 246-285°C, tensile strength of 23.1-33.8 MPa, and elongation at break of 3.5-13.1%. The membranes can be potentially applied for both acid and alkali recovery through diffusion dialysis (DD) process. The separation factor (S) for HCl/FeCl2 mixture can reach up to 89.9, which is about five times higher than that of commercial DF-120 membrane (18.5 at 25°C). The dialysis coefficients of NaOH (UOH) are in the range of 0.014-0.019 m/h, around 7-9 times higher than the value of commercial SPPO membrane (0.002 m/h at 25°C). The membranes also show potential usefulness for industrial acidic and alkali wastes treatment.

  14. Detection and Identification of the Keto-Hydroperoxide (HOOCH2OCHO) and Other Intermediates during Low-Temperature Oxidation of Dimethyl Ether.

    PubMed

    Moshammer, Kai; Jasper, Ahren W; Popolan-Vaida, Denisia M; Lucassen, Arnas; Diévart, Pascal; Selim, Hatem; Eskola, Arkke J; Taatjes, Craig A; Leone, Stephen R; Sarathy, S Mani; Ju, Yiguang; Dagaut, Philippe; Kohse-Höinghaus, Katharina; Hansen, Nils

    2015-07-16

    In this paper we report the detection and identification of the keto-hydroperoxide (hydroperoxymethyl formate, HPMF, HOOCH2OCHO) and other partially oxidized intermediate species arising from the low-temperature (540 K) oxidation of dimethyl ether (DME). These observations were made possible by coupling a jet-stirred reactor with molecular-beam sampling capabilities, operated near atmospheric pressure, to a reflectron time-of-flight mass spectrometer that employs single-photon ionization via tunable synchrotron-generated vacuum-ultraviolet radiation. On the basis of experimentally observed ionization thresholds and fragmentation appearance energies, interpreted with the aid of ab initio calculations, we have identified HPMF and its conceivable decomposition products HC(O)O(O)CH (formic acid anhydride), HC(O)OOH (performic acid), and HOC(O)OH (carbonic acid). Other intermediates that were detected and identified include HC(O)OCH3 (methyl formate), cycl-CH2-O-CH2-O- (1,3-dioxetane), CH3OOH (methyl hydroperoxide), HC(O)OH (formic acid), and H2O2 (hydrogen peroxide). We show that the theoretical characterization of multiple conformeric structures of some intermediates is required when interpreting the experimentally observed ionization thresholds, and a simple method is presented for estimating the importance of multiple conformers at the estimated temperature (∼100 K) of the present molecular beam. We also discuss possible formation pathways of the detected species: for example, supported by potential energy surface calculations, we show that performic acid may be a minor channel of the O2 + ĊH2OCH2OOH reaction, resulting from the decomposition of the HOOCH2OĊHOOH intermediate, which predominantly leads to the HPMF.

  15. The effect of solution chemistry on the preparation of MgAl{sub 2}O{sub 4} by hydrothermal-assisted sol-gel processing

    SciTech Connect

    Amini, M.M. . E-mail: m-pouramini@cc.sbu.ac.ir; Mirzaee, M.; Sepanj, N.

    2007-03-22

    Preparation of magnesium aluminate spinel powder by hydrothermal-assisted sol-gel processing from MgAl{sub 2}(OCH{sub 2}CH{sub 2}OR){sub 8}, R=CH{sub 3} (1), CH{sub 2}CH{sub 2}OCH{sub 3} (2), MgAl{sub 2}[OCH(CH{sub 3}){sub 2}]{sub 8} (3) and MgAl{sub 2}(O- {sup s}Bu){sub 8} (4) in toluene and parent alcohol has been investigated. Coordination status of aluminum atom in precursors was determined by {sup 27}Al NMR and correlation between coordination number of aluminum and development of spinel phase in hydrothermal-assisted sol-gel processing has been studied. The gels obtained from hydrothermal-assisted hydrolysis of magnesium-aluminum alkoxides that contain six-coordinated aluminum atoms in solution (1 and 2) after calcination at 700 deg. C resulted in the formation of pure spinel phase, whereas in similar hydrolysis and calcination processes of precursors that contain four-coordinated aluminum (3 and 4) spinel phase forms along with some Al{sub 2}O{sub 3} and MgO. Selected powders obtained from hydrothermal-assisted sol-gel processing were characterized by thermal analysis (TGA/DSC), X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). Results indicate that the coordination status of aluminum in the precursor is very crucial for the formation of pure phase spinel. The morphology of prepared spinels was studied by SEM and the results showed that the solvent in hydrothermal-assisted sol-gel processing has a marked effect on the morphology of the resulting MgAl{sub 2}O{sub 4}. In hydrothermal-assisted sol-gel processing of aluminum-magnesium alkoxides in hydrophobic solvent, spherical particles are formed, while in the parent alcohol, non-spherical powders are formed.

  16. Structure-spectroscopic property relationships in a series of platinum acetylides

    NASA Astrophysics Data System (ADS)

    Cooper, Thomas M.; Haley, Joy E.; Krein, Douglas M.; Burke, Aaron R.; Slagle, Jonathan E.

    2016-09-01

    In order to understand electronic and conformational effects on structure-spectroscopic property relationships in platinum acetylides, we synthesized a model series of chromophores trans-Pt(PBu3)2(C-CPhenyl-X)2, where X = NH2, OCH3, diphenylamino, t-Bu, methyl, H, F, benzothiazole, trifluoromethyl, CN and nitro. We collected linear spectra, including ground state absorption, phosphorescence and phosphorescence excitation spectra. We also performed DFT and TDDFT calculations on the ground and excited state properties of these compounds. The calculations and experimental data show the excited state properties are a function of the electronic properties of the substituents and the molecular conformation.

  17. New leads in speculative behavior

    NASA Astrophysics Data System (ADS)

    Kindler, A.; Bourgeois-Gironde, S.; Lefebvre, G.; Solomon, S.

    2017-02-01

    The Kiyotaki and Wright (1989) (henceforth KW) model of money emergence as a medium of exchange has been studied from various perspectives in recent papers. In the present work we propose a minimalistic model for the behavior of agents in the KW framework, which may either reproduce the theoretical predictions of Kiyotaki and Wright (1989) on the emerging Nash equilibria, or (less closely) the empirical results of Brown (1996), Duffy and Ochs (1999) and our own, introduced in a first part of the present paper. The main import is the systematic computer scanning of speculative monetary equilibria under drastic bounded rationality of agents, based on behavior previously observed in the lab.

  18. Theoretical study of the pyrolysis of vanillin as a model of secondary lignin pyrolysis

    NASA Astrophysics Data System (ADS)

    Wang, Meng; Liu, Chao; Xu, Xiaoxiao; Li, Qibin

    2016-06-01

    The unimolecular and bimolecular decomposition reactions in processes of vanillin pyrolysis were theoretically investigated by employing density functional theory (DFT) method at M06-2X/6-31 G+(d,p) level. The result shows that the homolytic cleavage of O-CH3 bond could be the dominant initial step in the pyrolysis of vanillin. The hydrogen abstractions from functional groups of vanillin by the formed radicals play important roles in the formation of main products. Both formyl, hydroxyl and methoxyl group contribute to the formation of CO. Benzene is formed from the hydrogen addition reaction between hydrogen radical and phenol at high temperature.

  19. Adsorption of Trimethyl Phosphite on H-KA, H-NaA, H-CaA and H-NaX Zeolites: an IR Study

    NASA Astrophysics Data System (ADS)

    Çiçek, E.; Bardakçı, B.; Ucun, F.; Bahçeli, S.

    2003-06-01

    Infrared spectroscopy has been used in adsorption studies of trimethyl phosphite (TMP) on the hydrogen (H) form of the A-type and 13X zeolites. Infrared spectra of H-zeolites, except H-KA, show that TMP reacts rapidly with silanol hydroxyls on their surfaces and gives rise to form product molecules such as SiOCH3 and liquid dimethyl phosphite. The unaccomplished adsorption on the H-KA zeolite has been attributed to the occurence of stable KOH hydroxyls with not-exchanged K cations instead of SiOH hydroxyls on this zeolite.

  20. Determination of the Minimum Energy Conformations of Benzyl Alcohol and 2-Phenethyl Alcohol

    DTIC Science & Technology

    1989-12-14

    ethylbenzyl alcohol (4-EtBA), 2 - methylbenzyl alcohol (2 -MeBA), 3- methylbenzyl alcohol (3-MeBA), 2 -PEA, 2-(o-methyl phenyl)-ethanol (2-(o-CH3)-PEA...conformers in the ground state. 3. 3- Methylbenzyl alcohol and 3-Fluorobenzyl alcohol The TOFMS of jet-cooled 3-MeBA is presented in Fig. 3. As found...these peaks are thus exactly the same as those for BA. This molecule has a single stable conformer, just as BA. 4. 2- Methylbenzyl alcohol The mass

  1. Propenyl ether monomers for photopolymerization

    DOEpatents

    Crivello, J.V.

    1996-10-22

    Propenyl ether monomers of formula A(OCH{double_bond}CHCH{sub 3}){sub n} wherein n is an integer from one to six and A is selected from cyclic ethers, polyether and alkanes are disclosed. The monomers are readily polymerized in the presence of cationic photoinitiators, when exposed to actinic radiation, to form poly(propenyl ethers) that are useful for coatings, sealants, varnishes and adhesives. Compositions for preparing polymeric coatings comprising the compounds of the above formula together with particular cationic photoinitiators are also disclosed, as are processes for making the monomers from allyl halides and readily available alcohols. The process involves rearranging the resulting allyl ethers to propenyl ethers.

  2. Process for making propenyl ethers and photopolymerizable compositions containing them

    DOEpatents

    Crivello, J.V.

    1996-01-23

    Propenyl ether monomers of formula A(OCH{double_bond}CHCH{sub 3}){sub n} (V) wherein n is an integer from one to six and A is selected from cyclic ethers, polyether, and alkanes are disclosed. The monomers are readily polymerized in the presence of cationic photoinitiators, when exposed to actinic radiation, to form poly(propenyl ethers) that are useful for coatings, sealants, varnishes and adhesives. Compositions for preparing polymeric coatings comprising the compounds of formula V together with particular cationic photoinitiators are also disclosed, as are processes for making the monomers from allyl halides and readily available alcohols. The process involves rearranging the resulting allyl ethers to propenyl ethers.

  3. Mass analyzed threshold ionization spectroscopy of p-methylanisole cation and the substitution effect

    NASA Astrophysics Data System (ADS)

    Huang, Jiangou; Li, Changyong; Tzeng, Wen Bih

    2005-10-01

    The adiabatic ionization energy of p-methylanisole is measured to be 63 972 ± 5 cm -1, which is red-shifted with respect to those of anisole and toluene. This indicates that the interaction of either CH 3 or OCH 3 group with the ring is stronger in the cationic D 0 state than that in the neutral S 0 state. Most of the observed MATI bands result from in-plane ring vibrations. The frequencies of vibrations 9b, 6a, and 1 of the p-methylanisole cation are found to be 407, 515, and 811 cm -1, respectively.

  4. Energy In Action: The Construction Of Physics Ideas In Multiple Modes

    NASA Astrophysics Data System (ADS)

    Close, Eleanor W.; Close, Hunter G.; McKagan, Sarah B.; Scherr, Rachel E.

    2010-10-01

    In a course organized around the development of diverse representations, no single mode of expression offers a complete picture of participants' understanding of the nature of energy. Instead, we argue, their understanding is actively constructed through the simultaneous use of a range of quite different kinds of representational resources (Goodwin, 2000; Hutchins, 1995; Ochs, Gonzales, & Jacoby, 1996), including not only words and prosody but also gestures, symbolic objects, participants moving their bodies in concert, and whatever other communicative modes the course invites them to use. Examples are provided from a teacher professional development course on energy.

  5. Multidimensional intermittency in hadronic collisions

    NASA Astrophysics Data System (ADS)

    Pan, Jicai; Hwa, Rudolph C.

    1992-12-01

    The study of intermittency in high-energy hadronic collisions by the Monte Carlo code ecco is extended to three-dimensional phase space. Strong intermittency is found in agreement with the data. Fluctuation in the impact parameter is responsible for the intermittency in lnpT, and the transverse-momentum conservation leads to negative intermittency slopes in the azimuthal angle φ. The Ochs-Wosiek plots are linear in all dimensions having universal slopes. An exponent ν=1.448 emerges to characterize multiparticle production in pp collisions. The properties of G moments are also examined, and the fractal dimensions determined.

  6. Multidimensional intermittency in hadronic collisions

    NASA Astrophysics Data System (ADS)

    Pan, J.; Hwa, R. C.

    1992-06-01

    The study of intermittency in high-energy hadronic collisions by the Monte Carlo code ECCO is extended to 3-dimensional phase space. Strong intermittency is found in agreement with the data. Fluctuation in the impact parameter is responsible for the intermittency in 1np(sub T), and the transverse-momentum conservation leads to negative intermittency slopes in the azimuthal angle (phi). The Ochs-Wosiek plots are linear in all dimensions having universal slopes. An exponent nu = 1.448 emerges to characterize multiparticle production in pp collisions. The properties of G moments are also examined, and the fractal dimensions determined.

  7. Outer scale of atmospheric turbulence

    NASA Astrophysics Data System (ADS)

    Lukin, Vladimir P.

    2005-10-01

    In the early 70's, the scientists in Italy (A.Consortini, M.Bertolotti, L.Ronchi), USA (R.Buser, Ochs, S.Clifford) and USSR (V.Pokasov, V.Lukin) almost simultaneously discovered the phenomenon of deviation from the power law and the effect of saturation for the structure phase function. During a period of 35 years we have performed successively the investigations of the effect of low-frequency spectral range of atmospheric turbulence on the optical characteristics. The influence of the turbulence models as well as a outer scale of turbulence on the characteristics of telescopes and systems of laser beam formations has been determined too.

  8. Vinyloxychloro-cyclotriphosphazenes.

    DTIC Science & Technology

    1982-12-06

    SECURITY CLASSIFICATION OF THIS PAGE (When De( Ente*d- 82 12 2() 001 OFFICE OF NAVAL RESEARCH Contract NOQ477C-0605 Project NIf 356-663 Technical Report No...Jpc : 7.32; 6-N(Me2 )=36.3 (d); 3JpC = 3.7; 016 6 831 6 = ( C - H ) ( ~ -2 2-P(OCHfCH2 )2 group: C - 141.8 (s), C8 - 100.4 (W). P NMR: -P(OCH-CH2

  9. Aerodynamics of Power Plant Installation

    DTIC Science & Technology

    1981-09-01

    dtant dquipd de 5 prisos de preasion d’arret ; Is valeur stationnAire eat relevde en extrdmitA du tube d’amortissement grflce A un capteur consnutd...doen is bande 0,2 Hz - 630 Hz, l’dchantilionnage eat raialisd do des nivesux de contrainte. rencontrds. Un capteur d’accdldration dtait dgaiement...informetionafournies par len capteurs ntationflaires pour un nombte de Mach moyen dens Iy ma och. vo~isn do 0,43. Cotte carte eat I comparer 4 cellia

  10. On the family- and genus-series nomina in Gyrinidae Latreille, 1810 (Coleoptera, Adephaga).

    PubMed

    Gustafson, Grey T; Miller, Kelly B

    2013-10-29

    All available genus- and family- group nomina for the Gyrinidae (Coleoptera: Adephaga) are listed along with original citation, original and current status, type nominal taxon with method of designation, and known synonymies and incorrect subsequent spellings. The nomina included follow the most current classification. Discussion is provided clarifying numerous nomenclatural problems with original spellings, correct authorship and type designation. Dineutini Ochs, 1926 syn. nov. is found to be a junior homonym of Dineutini Desmarest, 1851, and Enhydrini Régimbart, 1882 syn. nov. and its justified emendation Enhydrusini (Anonymous 2012) are here synonymized with Dineutini Desmarest, 1851.

  11. Syntheses of 4,6'-epoxymorphinan derivatives and their pharmacologies.

    PubMed

    Nemoto, Toru; Fujii, Hideaki; Narita, Minoru; Miyoshi, Kan; Nakamura, Atsushi; Suzuki, Tsutomu; Nagase, Hiroshi

    2008-04-15

    A modification of the message site in the skeleton of naltrexone was carried out to improve the potency and selectivity of the compound for an opioid receptor subtype. In the course of conversion, we synthesized 7-membered ring ether derivatives, which had an inserted OCH(2) group between 4- and 6-positions of morphinan skeleton. One of the 7-membered ring ether derivatives possessed more potent antagonistic activity than naltrexone for the mu opioid receptor. Another compound possessing 17-methyl group derived from noroxycodone may be a mu opioid receptor partial agonist and showed analgesic activity. We are currently examining the subtype selectivity of these compounds.

  12. Synthesis of homoleptic barium alkoxides and aryloxides and their reactions with Al(CH(3))(3): a convenient route to heterometallic species.

    PubMed

    Utko, Józef; Szafert, Sławomir; Jerzykiewicz, Lucjan B; Sobota, Piotr

    2005-07-25

    Reactions of metallic Ba with benzofuranol (dbbfoH) or diethylene glycol give homoleptic and homonuclear complexes Ba(dbbfo)(2)(dbbfoH)(2).3dbbfoH and Ba{O(CH(2)CH(2)O)(2)}{O(CH(2)CH(2)OH)(2)}(2) (60-89%). Both compounds and formerly described Ba{O(CH(2)CH(2)O)(2)Me}(2) react with Al(CH(3))(3) to yield trinuclear heterobimetallic low-coordinated barium compounds with structure and geometry depending on the reaction stoichiometry and crystallization procedure.

  13. Triaryl (Z)-olefins suitable for radiolabeling with iodine-124 or fluorine-18 radionuclides for positron emission tomography imaging of estrogen positive breast tumors.

    PubMed

    Abdellatif, Khaled R A; Velázquez, Carlos A; Huang, Zhangjian; Chowdhury, Morshed A; Knaus, Edward E

    2011-02-15

    A group of (Z)-1,2-diphenyl-1-[4-[2-(4-methylpiperazin-1-yl)ethoxy]phenyl]but-1-enes were synthesized using methodologies that will allow incorporation of a [(124)I]iodine substituent at the para-position of either the C-1 phenyl ring or the C-2 phenyl ring, or a [(18)F]OCH(2)CH(2)F substituent at the para-position of the C-2 phenyl ring. These [(124)I] and [(18)F] radiotracers are designed as potential radiopharmaceuticals to image estrogen positive breast tumors using positron emission tomography (PET).

  14. Research on Organofluorine Chemistry for 700 Degrees F Thermooxidative Stability

    DTIC Science & Technology

    1994-06-29

    8217) 4 NC-OC (CF’), CH, + NC- OCH2CF3 The products can be readily converted to amides , i.e., R-O CN H O,/KOH >C2H3OH 0()~ Conversion of these amides ...isopropyl)phenyl, pentamethylcyclopentadiene (Cp’), (b) highly substituted methyl systems, e.g., bis (trimethylsilyl)methyl and tris(trimethylsilyl)methyl... fluorosulfonyl derivatives, find application in the production of strong sulfonic acids, ion-exchange resins, surface active agents and perfluorinated

  15. Characterization of supramolecular (H2O)18 water morphology and water-methanol (H2O)15(CH3OH)3 clusters in a novel phosphorus functionalized trimeric amino acid host.

    PubMed

    Raghuraman, Kannan; Katti, Kavita K; Barbour, Leonard J; Pillarsetty, Nagavarakishore; Barnes, Charles L; Katti, Kattesh V

    2003-06-11

    Phosphorus functionalized trimeric alanine compounds (l)- and (d)-P(CH(2)NHCH(CH(3))COOH)(3) 2 are prepared in 90% yields by the Mannich reaction of Tris(hydroxymethyl)phosphine 1 with (l)- or (d)- Alanine in aqueous media. The hydration properties of (l)-2 and (d)-2 in water and water-methanol mixtures are described. The crystal structure analysis of (l)-2.4H(2)O, reveals that the alanine molecules pack to form two-dimensional bilayers running parallel to (001). The layered structural motif depicts two closely packed monolayers of 2 each oriented with its phosphorus atoms projected at the center of the bilayer and adjacent monolayers are held together by hydrogen bonds between amine and carboxylate groups. The water bilayers are juxtaposed with the H-bonded alanine trimers leading to 18-membered (H(2)O)(18) water rings. Exposure of aqueous solution of (l)-2 and (d)-2 to methanol vapors resulted in closely packed (l)-2 and (d)-2 solvated with mixed water-methanol (H(2)O)(15)(CH(3)OH)(3) clusters. The O-O distances in the mixed methanol-water clusters of (l)-2.3H(2)O.CH(3)OH and (d)-2.3H(2)O.CH(3)OH (O-O(average) = 2.857 A) are nearly identical to the O-O distance observed in the supramolecular (H(2)O)(18) water structure (O-O(average) = 2.859 A) implying the retention of the hydrogen bonded structure in water despite the accommodation of hydrophobic methanol groups within the supramolecular (H(2)O)(15)(CH(3)OH)(3) framework. The O-O distances in (l)-2.3H(2)O.CH(3)OH and (d)-2.3H(2)O.CH(3)OH and in (H(2)O)(18) are very close to the O-O distance reported for liquid water (2.85 A).

  16. Contact sensitivity to nonoxynols as a cause of intolerance to antiseptic preparations.

    PubMed

    Dooms-Goossens, A; Deveylder, H; de Alam, A G; Lachapelle, J M; Tennstedt, D; Degreef, H

    1989-10-01

    Twelve cases of allergic contact dermatitis caused by antiseptic preparations are presented. The reactions resulted not from the active principles but rather from nonoxynols used in the offending substances as nonionic surface-active agents. Nonoxynols are ethoxylated alkyl phenols or nonylphenylethers that conform in general to the formula C9H19C6H4(OCH2CH2)nOH. They have emulsifying, wetting, foaming, and solubilizing properties and are used in a large number of industrial, household, agricultural, cosmetic, and pharmaceutical products. They also are used as spermicides. There are very few reports in the literature of skin problems caused by nonoxynols.

  17. The Formation of N- and O-Heterocycles from the Irradiation of Benzene and Naphthalene in H2O/NH3- Containing Ices

    NASA Technical Reports Server (NTRS)

    Sandford, S. A.; Materese, C. K.; Nuevo, M.

    2015-01-01

    Aromatic hydrocarbons are an important class of molecules for both astrochemistry and astrobiology (Fig. 1). Within this class of molecules, polycyclic aromatic hydrocarbons (PAHs) are known to be ubiquitous in many astrophysical environments, and are likely present in interstellar clouds and protostellar disks. In dense clouds, PAHs are expected to condense onto grains as part of mixed molecular ice mantles dominated by small molecules like H2O,CH3OH, NH3, CO, and CO2. These ices are exposed to ionizing radiation in the form of cosmic rays and ambient high-energy X-ray and UV photons.

  18. Phosphazenes with Olefinic Side Groups: Proton Abstraction Reactions of Fluoroalkoxy Derivatives.

    DTIC Science & Technology

    1982-06-24

    OPh) (OC(Li)=CF2) 13 and [NP(OC(Li)CF2)2]3 1 respectively. These species are stable in solution at -78*C, but react with electrophiles such as 2...an -OCH2CF3 side group to generate an -OC(M)-CF2 unit. Subsequent treatment with an electrophile was designed to yield an -OC(R)-CF2 side group...resonances for the fluorine atoms in 2 and 5 appeared as multiplets due to the slight differences in chemical shift between the cis and trans

  19. 1-(2-Thienyl)-2-phenylethylamines as potential non-stimulant anorectics.

    PubMed

    Mrongovius, R I; Ghosh, P; Bolt, A G; Ternai, B

    1981-01-01

    A series of 1-(2-thienyl)-2-phenylethylamines was synthesized and tested for anorectic and motor activity effects in rats. Phenyl ring substituents included Cl, Br, F, CF3, CH3, OCH3, and NO2; amino group substituents included alkyl, benzyl and acetyl groups. About half of the compounds produced significant anorexia; only one of these active anorectics increased motor activity. The three most potent non-stimulant anorectics were: 1-(2-thienyl)-2-(4-chlorophenyl)ethylamine, its N-isopropyl analogue, and N-isopropyl-1-(2-thienyl)-2-(4-fluorophenyl)ethylamine.

  20. Increasing the activity and enantioselectivity of lipases by sol-gel immobilization: further advancements of practical interest

    NASA Astrophysics Data System (ADS)

    Tielmann, Patrick; Kierkels, Hans; Zonta, Albin; Ilie, Adriana; Reetz, Manfred T.

    2014-05-01

    The entrapment of lipases in hydrophobic silicate matrices formed by sol-gel mediated hydrolysis of RSi(OCH3)3/Si(OCH3)4 as originally reported in 1996 has been improved over the years by a number of modifications. In the production of second-generation sol-gel lipase immobilizates, a variety of additives during the sol-gel process leads to increased activity and enhanced stereoselectivity in esterifying kinetic resolution. Recent advances in this type of lipase immobilization are reviewed here, in addition to new results regarding the sol-gel entrapment of the lipase from Burkholderia cepacia. It constitutes an excellent heterogeneous biocatalyst in the acylating kinetic resolution of two synthetically and industrially important chiral alcohols, rac-sulcatol and rac-trans-2-methoxycyclohexanol. The observation that the catalyst can be used 10 times in recycling experiments without losing its significant activity or enantioselectivity demonstrates the practical viability of the sol-gel approach.The entrapment of lipases in hydrophobic silicate matrices formed by sol-gel mediated hydrolysis of RSi(OCH3)3/Si(OCH3)4 as originally reported in 1996 has been improved over the years by a number of modifications. In the production of second-generation sol-gel lipase immobilizates, a variety of additives during the sol-gel process leads to increased activity and enhanced stereoselectivity in esterifying kinetic resolution. Recent advances in this type of lipase immobilization are reviewed here, in addition to new results regarding the sol-gel entrapment of the lipase from Burkholderia cepacia. It constitutes an excellent heterogeneous biocatalyst in the acylating kinetic resolution of two synthetically and industrially important chiral alcohols, rac-sulcatol and rac-trans-2-methoxycyclohexanol. The observation that the catalyst can be used 10 times in recycling experiments without losing its significant activity or enantioselectivity demonstrates the practical viability of

  1. [Oligonucleotide analogues bearing an acyclonucleoside linked by an internucleotide amide bond].

    PubMed

    Kochetkova, S V; Fillipova, E A; Kolganova, N A; Timofeev, E N; Florent'ev, V L

    2008-01-01

    Oligonucleotide analogues bearing an acyclocytidine linked to thymidine by an amide (3'-O-CH2-CO-N-5') bond were synthesized. Melting curves of duplexes formed by modified oligonucleotides and complementary natural oligomers were obtained and thermodynamic parameters of their formation were measured. Replacement of dCpT by a modified dinucleotide only moderately decreased the melting temperature of these modified duplexes in comparison with unmodified duplexes containing complementary natural bases. CD spectra of modified duplexes were studied, and the duplex spatial structures are discussed. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2008, vol. 34, no. 2; see also http://www.maik.ru.

  2. Non-Lethal Defense III, Johns Hopkins Applied Physics Laboratory, Laurel, Maryland, February 25 & 26, 1998, Revised Agenda.

    DTIC Science & Technology

    1998-02-26

    CH-CH3 R, -CH2 -O-CH2 -CH-OH 0 CH 3 Scheme 3 In Scheme 2, each primary hydroxyl group in the polyol is reacted with lactic acid to produce a terminal...as they arrived. As with all conferences of this nature , a number of people have worked for several months to pull it all together. We are indebted...or LTL weapons were developed in this period-the taser (which fires two wire-tethered barbs) and the less lethal kinetic munitions (such as rubber

  3. An effective route to fluorine containing asymmetric alpha-aminophosphonates using chiral Bronsted acid catalyst.

    PubMed

    Bhadury, Pinaki S; Zhang, Yuping; Zhang, Sha; Song, Baoan; Yang, Song; Hu, Deyu; Chen, Zhuo; Xue, Wei; Jin, Linhong

    2009-05-01

    Asymmetric addition of dialkyl phosphites (--CH2CH3, --CH2CH2CH3, --CH(CH3)2, --CH2(CH2)3CH3, --CH2CH2OCH3 and --CH2CH2OC2H5) induced by chiral organocatalyst e.g. (R)- and (S)-3,3'-[3,5-bis(trifluoromethyl)phenyl]2-1,1'-binaphthyl phosphate on fluorinated aldimines derived from cinnamaldehyde has been found effective to give new bioactive alpha-aminophosphonates in good yields (58-73%) and high enantiomeric excess (64.6%-90.6%) under mild conditions.

  4. Viscosity of Metals in Explosion Welding

    DTIC Science & Technology

    1974-11-19

    bglish sin fin can coo tg tan ct cot oh sinh oh cooh th tanh cth ooth Bh ech cch coch arc sin ow 1 arc coo OO8ŕ arc tg tan-1 arc ctg oot ŕ are ec...30c1l arc cooe 080 ŕ arc oh minhŕ arc ch cooh - 1 are tim tan- arc oth coth-1 arc sch ch-1 arc och coch -1 rot curl Ig log FTD-HT-23-1992-74 ii GREEK

  5. FTIR gas-phase kinetic study on the reactions of some acrylate esters with OH radicals and Cl atoms.

    PubMed

    Moreno, A; Gallego-Iniesta, M P; Taccone, R; Martín, M P; Cabañas, B; Salgado, M S

    2014-10-01

    Acrylate esters are α,β-unsaturated esters that contain vinyl groups directly attached to the carbonyl carbon. These compounds are widely used in the production of plastics and resins. Atmospheric degradation processes of these compounds are currently not well understood. The kinetics of the gas phase reactions of OH radicals with methyl 3-methylacrylate and methyl 3,3-dimethylacrylate were determined using the relative rate technique in a 50 L Pyrex photoreactor using in situ FTIR spectroscopy at room temperature (298 ± 2 K) and atmospheric pressure (708 ± 8 Torr) with air as the bath gas. Rate coefficients obtained were (in units cm(3) molecule(-1) s(-1)): (3.27 ± 0.33) × 10(-11) and (4.43 ± 0.42) × 10(-11), for CH3CH═CHC(O)OCH3 and (CH3)2CH═CHC(O)OCH3, respectively. The same technique was used to study the gas phase reactions of hexyl acrylate and ethyl hexyl acrylate with OH radicals and Cl atoms. In the experiments with Cl, N2 and air were used as the bath gases. The following rate coefficients were obtained (in cm(3) molecule(-1) s(-1)): k3 (CH2═CHC(O)O(CH2)5CH3 + Cl) = (3.31 ± 0.31) × 10(-10), k4(CH2═CHC(O)OCH2CH(CH2CH3)(CH2)3CH3 + Cl) = (3.46 ± 0.31) × 10(-10), k5(CH2═CHC(O)O(CH2)5CH3 + OH) = (2.28 ± 0.23) × 10(-11), and k6(CH2═CHC(O)OCH2CH(CH2CH3)(CH2)3CH3 + OH) = (2.74 ± 0.26) × 10(-11). The reactivity increased with the number of methyl substituents on the double bond and with the chain length of the alkyl group in -C(O)OR. Estimations of the atmospheric lifetimes clearly indicate that the dominant atmospheric loss process for these compounds is their daytime reaction with the hydroxyl radical. In coastal areas and in some polluted environments, Cl atom-initiated degradation of these compounds can be significant, if not dominant. Maximum Incremental Reactivity (MIR) index and global warming potential (GWP) were also calculated, and it was concluded that these compounds have significant MIR values, but they do

  6. A zwitterionic carbanion frustrated by boranes--dihydrogen cleavage with weak Lewis acids via an "inverse" frustrated Lewis pair approach.

    PubMed

    Li, Hui; Aquino, Adelia J A; Cordes, David B; Hung-Low, Fernando; Hase, William L; Krempner, Clemens

    2013-10-30

    The synthesis, structural characterization, and acid-base chemistry of [C(SiMe2OCH2CH2OMe)3]Na (2), a sterically encumbered zwitterionic organosodium compound, is reported. 2 is a strong Brønsted base that forms frustrated Lewis pairs (FLPs) with a number of boron-containing Lewis acids ranging from weakly Lewis acidic aryl and alkyl boranes to various alkyl borates. These intermolecular FLPs readily cleave H2, which confirms that even poor Lewis acids can engage in FLP-mediated H2 cleavage provided that the present bulky base is of sufficiently high Brønsted basicity.

  7. Performance Evaluation of Potential Fuel System Icing Inhibitors in Aviation Jet Fuel Using the US Navy Aircraft Fuel System Icing Simulator

    DTIC Science & Technology

    1997-05-29

    candidate. Empirical formula: CgH14°4. o HC II 21’O~CH3 HC-CH3 HL....Oy CH32 I o 5 NAVAIRWARCENACDIVTRENTON-LR-PPE-97-3 (20) 2-Methyl-l,3- Propanediol ...friendly FSII candidate. Empirical formula: C4H1002. H2C-OH --/ HC- CH3 / H2C-OH (21) A mixture ofthree components (8% 2-Methy1-1,3- Propanediol ; 48% 3...Navy/U.S. Air ForceFSn development project; an environmentally friendly FSII candidate. 2-Methyl-l,3- Propanediol 3-Hydroxy-2-MethylPropyl Acetate + o

  8. Synthesis of Peptides Containing C-Terminal Methyl Esters Using Trityl Side-Chain Anchoring: Application to the Synthesis of a-Factor and a-Factor Analogs

    PubMed Central

    Diaz-Rodriguez, Veronica; Mullen, Daniel G.; Ganusova, Elena; Becker, Jeffrey M.; Distefano, Mark D.

    2012-01-01

    A new cysteine anchoring method was developed for the synthesis of peptides containing C-terminal cysteine methyl esters. This method consists of attachment of Fmoc-Cys-OCH3 to either 2-ClTrt-Cl or Trt-Cl resins (via the side-chain thiol) followed by preparation of the desired peptide using Fmoc-based SPPS. We applied this method to the synthesis of the mating pheromone a-factor and a 5-FAM labeled a-factor analog. The peptides were obtained with high yield and purity and were shown to be bioactive in a growth arrest assay. PMID:23121562

  9. Propenyl ether monomers for photopolymerization

    DOEpatents

    Crivello, James V.

    1996-01-01

    Propenyl ether monomers of formula V A(OCH.dbd.CHCH.sub.3).sub.n wherein n is an integer from one to six and A is selected from cyclic ethers, polyether and alkanes are disclosed. The monomers are readily polymerized in the presence of cationic photoinitiators, when exposed to actinic radiation, to form poly(propenyl ethers) that are useful for coatings, sealants, varnishes and adhesives. Compositions for preparing polymeric coatings comprising the compounds of formula V together with particular cationic photoinitiators are also disclosed, as are processes for making the monomers from allyl halides and readily available alcohols. The process involves rearranging the resulting allyl ethers to propenyl ethers.

  10. Process for making propenyl ethers and photopolymerizable compositions containing them

    DOEpatents

    Crivello, James V.

    1996-01-01

    Propenyl ether monomers of formula V A(OCH.dbd.CHCH.sub.3).sub.n wherein n is an integer from one to six and A is selected from cyclic ethers, polyether and alkanes are disclosed. The monomers are readily polymerized in the presence of cationic photoinitiators, when exposed to actinic radiation, to form poly(propenyl ethers) that are useful for coatings, sealants, varnishes and adhesives. Compositions for preparing polymeric coatings comprising the compounds of formula V together with particular cationic photoinitiators are also disclosed, as are processes for making the monomers from allyl halides and readily available alcohols. The process involves rearranging the resulting allyl ethers to propenyl ethers.

  11. Synthesis Laboratory for the U.S. Army Medical Research Institute of Infectious Diseases Selection Panel

    DTIC Science & Technology

    1988-01-19

    ANNUAL PROGRESS REPORT John A. Secrist III Cecil D. Kwong / Charles A. Krauth ’ Angela G. Ford Yajnanarayana H. R. Jois Deborah A. Carter...C. A. Krauth A. G. Ford H. R. Y. Jois D. A. Carter Analytical Services Dr. W. C. Coburn Dr. J. M. Riordan M. C. Kirk C. Richards R. T...7022 00361S 2.0 q /^ K ^^C=NNHCNHj *"S/ CH, 7023 003677 2.0 g S II C=NNHCNH, I 2 CH3 702> 003678 2.0 g NH "«1-®- OCH, HCIO„ 7037 003679

  12. Synthesis of peptides containing C-terminal methyl esters using trityl side-chain anchoring: application to the synthesis of a-factor and a-factor analogs.

    PubMed

    Diaz-Rodriguez, Veronica; Mullen, Daniel G; Ganusova, Elena; Becker, Jeffrey M; Distefano, Mark D

    2012-11-16

    A new cysteine anchoring method was developed for the synthesis of peptides containing C-terminal cysteine methyl esters. This method consists of attachment of Fmoc-Cys-OCH(3) to either 2-ClTrt-Cl or Trt-Cl resins (via the side-chain thiol) followed by preparation of the desired peptide using Fmoc-based SPPS. We applied this method to the synthesis of the mating pheromone a-factor and a 5-FAM labeled a-factor analog. The peptides were obtained with high yield and purity and were shown to be bioactive in a growth arrest assay.

  13. Alkylation of urinary guanine in mice by the organophosphorus insecticide tetrachlorvinphos.

    PubMed

    Zayed, S M; Mostafa, I Y; Hegazi, B

    1984-06-01

    The methylating capability of tetrachlorvinphos on urinary guanine in mice has been investigated using an insecticide labeled at both O-CH3 groups. Following intraperitoneal administration of the 14C-labeled insecticide to mice, about 0.57% of the radioactivity in the O- to 24-hr samples was associated with the purine fraction. The amount of [7-14C]methylguanine in 0- to 48-hr urine samples, estimated as fraction of applied dose, was 26-31 X 10(-5). The results obtained indicate possible chemical alkylation of urinary guanine. On the other hand, a considerable portion of radioactivity is probably incorporated via the C-1 pool.

  14. New sandwich-type lanthanide complexes based on closed-macrocyclic Schiff base and phthalocyanine molecules.

    PubMed

    Gao, Feng; Feng, Xiaowan; Yang, Liu; Chen, Xiaoyu

    2016-04-25

    Two new sandwich-type lanthanide complexes with the general formula [(Pc)2Ln3(L)(OAc)(OCH3)2] (Ln(3+) = Dy(3+) () and Er(3+) ()) were successfully synthesized and structurally characterized based on closed-macrocyclic Schiff base and phthalocyanine molecules. The magnetic properties and structure-property relationship in this multi-decker system were investigated. Interestingly, the corresponding dysprosium complex shows typical single-molecule magnetic behavior with ferromagnetic dipole-dipole interactions and the slow relaxation of magnetization.

  15. Electrospray ionization tandem mass spectrometric study of protonated and alkali- cationized α/ε-hybrid peptides: differentiation of a pair of dipeptide positional isomers.

    PubMed

    Ramesh Babu, A; Raju, G; Purna Chander, C; Shoban Babu, B; Srinivas, R; Sharma, G V M

    2016-01-01

    A new class of Boc-N-protected hybrid peptides derived from L- Ala and ε(6)-Caa (L-Ala = L-Alanine, Caa = C-linked carboamino acid derived from D-xylose) have been studied by positive ion electrospray ionization (ESI) ion-trap tandem mass spectrometry (MS/MS). MS(n) spectra of protonated and alkali-cationized hybrid peptides produce characteristic fragmentation involving the peptide backbone, the tert-butyloxycarbonyl (Boc) group, and the side chain. The dipeptide positional isomers are differentiated by the collision-induced dissociation (CID) of the protonated and alkali-cationized peptides. The CID of [M + H](+) ion of Boc-NH-L-Ala-ε-Caa- OCH3 (1) shows a prominent [M + H - C4H8](+) ion, which is totally absent for its positional isomer Boc-NH-ε-Caa-L-Ala-OCH3 (6), which instead shows significant loss of t-butanol. The formation of the [M + Cat - C4H8](+) ion is totally absent and [M + Cat - Boc + H](+) is prominent in the CID of the [M + Cat](+) ion of Boc-NH-L-Ala-ε-Caa- OCH3 (1), whereas the former is highly abundant and the latter is of low abundance for its positional isomer Boc-NH-ε-Caa-L-Ala-OCH3 (6). It is observed that 'b' ions are abundant when oxazolone structures are formed through a five-membered cyclic transition state in tetra-, penta-, and hexapeptides and the cyclization process for larger 'b' ions led to an insignificant abundance. However, the significant 'b' ion is formed in ε,α-dipeptide, which may have a seven-membered substituted 2-oxoazepanium ion structure. The MS(n) spectra of [M + Cat - Boc + H](+) ions of these peptides are found to be significantly different to those of [M + H - Boc + H](+) ions. The CID spectra of [M + Cat - Boc + H](+) ions of peptide acids containing L-Ala at the C-terminus show an abundant N-terminal rearrangement ion, [b(n) + 17 + Cat](+), which is absent for the peptide acids containing ε-Caa at the C-terminus. Thus, the results of these hybrid peptides

  16. Chapter 25 First-Principles Investigation of Dimethyl Ether Steam Reforming

    NASA Astrophysics Data System (ADS)

    Fukushima, Kimichika

    This paper reports the investigation of dimethyl ether (DME) steam reforming and related processes. The study uses the X[alpha] molecular orbital theory, which has been successfully applied to analyze material properties. It was found that, when H2O approaches Al on a surface of Si oxides (and pure Al2O3), charge transfer between H2O and the surface destabilizes the H2O. Approach of the destabilized H to a CH3OCH3 molecule then produces CH3OH. Finally, injection of CO2, by-produced in the reforming, to coal seam was shown to increase the CH4 production by substitution.

  17. Cyclodextrin Complexes of Reduced Bromonoscapine in Guar Gum Microspheres Enhance Colonic Drug Delivery

    PubMed Central

    2015-01-01

    Here, we report improved solubility and enhanced colonic delivery of reduced bromonoscapine (Red-Br-Nos), a cyclic ether brominated analogue of noscapine, upon encapsulation of its cyclodextrin (CD) complexes in bioresponsive guar gum microspheres (GGM). Phase–solubility analysis suggested that Red-Br-Nos complexed with β-CD and methyl-β-CD in a 1:1 stoichiometry, with a stability constant (Kc) of 2.29 × 103 M–1 and 4.27 × 103 M–1. Fourier transforms infrared spectroscopy indicated entrance of an O–CH2 or OCH3–C6H4–OCH3 moiety of Red-Br-Nos in the β-CD or methyl-β-CD cavity. Furthermore, the cage complex of Red-Br-Nos with β-CD and methyl-β-CD was validated by several spectral techniques. Rotating frame Overhauser enhancement spectroscopy revealed that the Ha proton of the OCH3–C6H4–OCH3 moiety was closer to the H5 proton of β-CD and the H3 proton of the methyl-β-CD cavity. The solubility of Red-Br-Nos in phosphate buffer saline (PBS, pH ∼ 7.4) was improved by ∼10.7-fold and ∼21.2-fold when mixed with β-CD and methyl-β-CD, respectively. This increase in solubility led to a favorable decline in the IC50 by ∼2-fold and ∼3-fold for Red-Br-Nos−β-CD-GGM and Red-Br-Nos–methyl-β-CD-GGM formulations respectively, compared to free Red-Br-Nos−β-CD and Red-Br-Nos–methyl-β-CD in human colon HT-29 cells. GGM-bearing drug complex formulations were found to be highly cytotoxic to the HT-29 cell line and further effective with simultaneous continuous release of Red-Br-Nos from microspheres. This is the first study to showing the preparation of drug-complex loaded GGMS for colon delivery of Red-Br-Nos that warrants preclinical assessment for the effective management of colon cancer. PMID:25350222

  18. Abolishment of N-glycan mannosylphosphorylation in glyco-engineered Saccharomyces cerevisiae by double disruption of MNN4 and MNN14 genes.

    PubMed

    Kim, Yeong Hun; Kang, Ji-Yeon; Gil, Jin Young; Kim, Sang-Yoon; Shin, Keun Koo; Kang, Hyun Ah; Kim, Jeong-Yoon; Kwon, Ohsuk; Oh, Doo-Byoung

    2017-04-01

    Mannosylphosphorylated glycans are found only in fungi, including yeast, and the elimination of mannosylphosphates from glycans is a prerequisite for yeast glyco-engineering to produce human-compatible glycoproteins. In Saccharomyces cerevisiae, MNN4 and MNN6 genes are known to play roles in mannosylphosphorylation, but disruption of these genes does not completely remove the mannosylphosphates in N-glycans. This study was performed to find unknown key gene(s) involved in N-glycan mannosylphosphorylation in S. cerevisiae. For this purpose, each of one MNN4 and five MNN6 homologous genes were deleted from the och1Δmnn1Δmnn4Δmnn6Δ strain, which lacks yeast-specific hyper-mannosylation and the immunogenic α(1,3)-mannose structure. N-glycan profile analysis of cell wall mannoproteins and a secretory recombinant protein produced in mutants showed that the MNN14 gene, an MNN4 paralog with unknown function, is essential for N-glycan mannosylphosphorylation. Double disruption of MNN4 and MNN14 genes was enough to eliminate N-glycan mannosylphosphorylation. Our results suggest that the S. cerevisiae och1Δmnn1Δmnn4Δmnn14Δ strain, in which all yeast-specific N-glycan structures including mannosylphosphorylation are abolished, may have promise as a useful platform for glyco-engineering to produce therapeutic glycoproteins with human-compatible N-glycans.

  19. 2-Methoxyphenyl isocyanate and 2-Methoxyphenyl isothiocyanate: conformers, vibration structure and multiplet Fermi resonance.

    PubMed

    Yenagi, Jayashree; Nandurkar, Anita R; Tonannavar, J

    2012-06-01

    IR and Raman spectral measurements in the region 3500-400/50 cm(-1) have been made for the liquid samples of 2-Methoxyphenyl isocyanate and 2-Methoxyphenyl isothiocyanate. A complete assignment of the measured bands has been proposed as aided by conformational and vibration analyses at B3LYP/6-311++G** level of calculations. Three conformers for 2-Methoxyphenyl isocyanate and two for 2-Methoxyphenyl isothiocyanate have been determined. The tilt of the isocyanate (NCO) and isothiocyanate (NCS) moieties with respect to phenyl ring are in broad agreement with their parents. Stretching mode frequencies of methyl group (-OCH(3)) in 2-Methoxyphenyl isocyanate have been lowered in the 2900-2800 cm(-1); deformation asymmetric modes are IR strong and symmetric one Raman strong. In 2-Methoxyphenyl isothiocyanate, a similar pattern is true for stretching modes but deformation asymmetric modes are IR strong and symmetric mode has not been observed. Multiplet absorption band system near 2200 cm(-1) in 2-Methoxyphenyl isocyanate has been interpreted to be caused by Fermi resonance. A similar pattern in absorption near 2100 cm(-1) in 2-Methoxyphenyl isothiocyanate but more complex Raman band pattern has also been explained through Fermi resonance from heuristic stand-point. Many Raman modes in 1300-1100 cm(-1) are intensified apparently owing to isothiocyanate than isocyanate moiety. Phenyl ring breathing mode is shifted to 1040 cm(-1) as strong Raman; the symmetric stretching mode of O-CH(3) near 1023 cm(-1) as strong absorption.

  20. Nucleophilic substitution at silicon (SN2@Si) via a central reaction barrier.

    PubMed

    Bento, A Patrícia; Bickelhaupt, F Matthias

    2007-03-16

    It is textbook knowledge that nucleophilic substitution at carbon (SN2@C) proceeds via a central reaction barrier which disappears in the corresponding nucleophilic substitution reaction at silicon (SN2@Si). Here, we address the question why the central barrier disappears from SN2@C to SN2@Si despite the fact that these processes are isostructural and isoelectronic. To this end, we have explored and analyzed the potential energy surfaces (PES) of various Cl-+CR3Cl (R=H, CH3) and Cl-+SiR3Cl model reactions (R=H, CH3, C2H5, and OCH3). Our results show that the nature of the SN2 reaction barrier is in essence steric, but that it can be modulated by electronic factors. Thus, simply by increasing the steric demand of the substituents R around the silicon atom, the SN2@Si mechanism changes from its regular single-well PES (with a stable intermediate transition complex, TC), via a triple-well PES (with a pre- and a post-TS before and after the central TC), to a double-well PES (with a TS; R=OCH3), which is normally encountered for SN2@C reactions.

  1. Direct ab initio molecular dynamics study on a microsolvated SN2 reaction of OH-(H2O) with CH3Cl.

    PubMed

    Tachikawa, Hiroto

    2006-10-07

    Reaction dynamics for a microsolvated SN2 reaction OH-(H2O)+CH3Cl have been investigated by means of the direct ab initio molecular dynamics method. The relative center-of-mass collision energies were chosen as 10, 15, and 25 kcal/mol. Three reaction channels were found as products. These are (1) a channel leading to complete dissociation (the products are CH3OH+Cl- +H2O: denoted by channel I), (2) a solvation channel (the products are Cl-(H2O)+CH3OH: channel II), and (3) a complex formation channel (the products are CH3OH...H2O+Cl-: channel III). The branching ratios for the three channels were drastically changed as a function of center-of-mass collision energy. The ratio of complete dissociation channel (channel I) increased with increasing collision energy, whereas that of channel III decreased. The solvation channel (channel II) was minor at all collision energies. The selectivity of the reaction channels and the mechanism are discussed on the basis of the theoretical results.

  2. Direct ab initio molecular dynamics study on a microsolvated SN2 reaction of OH-(H2O) with CH3Cl

    NASA Astrophysics Data System (ADS)

    Tachikawa, Hiroto

    2006-10-01

    Reaction dynamics for a microsolvated SN2 reaction OH-(H2O)+CH3Cl have been investigated by means of the direct ab initio molecular dynamics method. The relative center-of-mass collision energies were chosen as 10, 15, and 25kcal/mol. Three reaction channels were found as products. These are (1) a channel leading to complete dissociation (the products are CH3OH+Cl-+H2O: denoted by channel I), (2) a solvation channel (the products are Cl-(H2O)+CH3OH: channel II), and (3) a complex formation channel (the products are CH3OH ⋯H2O+Cl-: channel III). The branching ratios for the three channels were drastically changed as a function of center-of-mass collision energy. The ratio of complete dissociation channel (channel I) increased with increasing collision energy, whereas that of channel III decreased. The solvation channel (channel II) was minor at all collision energies. The selectivity of the reaction channels and the mechanism are discussed on the basis of the theoretical results.

  3. One-pot Solvothermal Synthesis of Well-ordered Layered Sodium Aluminoalcoholate Complex: A Useful Precursor for the Preparation of Porous Al2O3 Particles.

    PubMed

    Li, Xiansen; Michaelis, Vladimir K; Ong, Ta-Chung; Smith, Stacey J; McKay, Ian; Müller, Peter; Griffin, Robert G; Wang, Evelyn N

    2014-04-14

    One-pot solvothermal synthesis of a robust tetranuclear sodium hexakis(glycolato)tris(methanolato)aluminate complex Na3[Al4(OCH3)3(OCH2CH2O)6] via a modified yet rigorous base-catalyzed transesterification mechanism is presented here. Single crystal X-ray diffraction (SCXRD) studies indicate that this unique Al complex contains three penta-coordinate Al(3+) ions, each bound to two bidentate ethylene glycolate chelators and one monodentate methanolate ligand. The remaining fourth Al(3+) ion is octahedrally coordinated to one oxygen atom from each of the six surrounding glycolate chelators, effectively stitching the three penta-coordinate Al moieties together into a novel tetranuclear Al complex. This aluminate complex is periodically self-assembled into well-ordered layers normal to the [110] axis with the intra-/inter-layer bindings involving extensive ionic bonds from the three charge-counterbalancing Na(+) cations rather than the more typical hydrogen bonding interactions as a result of the fewer free hydroxyl groups present in its structure. It can also serve as a valuable precursor toward the facile synthesis of high-surface-area alumina powders using a very efficient rapid pyrolysis technique.

  4. Synthesis and biological evaluation of pyrazolylthiazole carboxylic acids as potent anti-inflammatory-antimicrobial agents.

    PubMed

    Khloya, Poonam; Kumar, Satish; Kaushik, Pawan; Surain, Parveen; Kaushik, Dhirender; Sharma, Pawan K

    2015-03-15

    Current Letter presents design, synthesis and biological evaluation of a novel series of pyrazolylthiazole carboxylates 1a-1p and corresponding acid derivatives 2a-2p. All 32 novel compounds were tested for their in vivo anti-inflammatory activity by carrageenan-induced rat paw edema method as well as for in vitro antimicrobial activity. All the tested compounds exhibited excellent AI activity profile. Three compounds 1p (R=Cl, R(1)=Cl), 2c (R=H, R(1)=F) and 2n (R=Cl, R(1)=OCH3) were identified as potent anti-inflammatory agents exhibiting edema inhibition of 93.06-89.59% which is comparable to the reference drug indomethacin (91.32%) after 3h of carrageenan injection while most of the other compounds displayed inhibition ⩾80%. In addition, pyrazolylthiazole carboxylic acids (2a-2p) also showed good antimicrobial profile. Compound 2h (R=OCH3, R(1)=Cl) showed excellent antimicrobial activity (MIC 6.25μg/mL) against both Gram positive bacteria comparable with the reference drug ciprofloxacin (MIC 6.25μg/mL).

  5. Magneto-Structural Analysis of Iron(III) Keggin Polyoxometalates.

    PubMed

    Bandeira, Nuno A G; Sadeghi, Omid; Woods, Toby J; Zhang, Yuan-Zhu; Schnack, Jürgen; Dunbar, Kim; Nyman, May; Bo, Carles

    2017-02-16

    A computational study and magnetic susceptibility measurements of three homonuclear Fe(III) Keggin structures are herein presented: the [FeO4@Fe12F24(μ-OCH3)12](5-) anion (1), the [Bi6{FeO4@Fe12O12(OH)12}(μ-O2CCCl3)12](+) cation (2) and its polymorph [Bi6{FeO4@Fe12O12(OH)10(H2O)2}(μ-O2CCF3)10](3+) (3). These results are contrasted with the exchange interactions present in the previously characterized [Fe6(OH)3Ge2W18O68(OH)6](11-) and [H12As4Fe8W30O120(H2O)2](4-) anions. The computational analysis shows that the most significant antiferromagnetic spin coupling takes place at the junction between each of the {Fe3O6(OH)3}/{Fe3F6(OCH3)3} framework motifs, a possibility that had been previously discarded in the literature on the basis of the Fe-Fe distances. For all the examined iron(III) Keggin structures, it is found that the magnitude of the magnetic couplings within each structural subunit follows the same trend.

  6. Synthesis and characterizations of anion exchange organic-inorganic hybrid materials based on poly(2,6-dimethyl-1,4-phenylene oxide) (PPO)

    SciTech Connect

    Zhang Shaoling; Wu Cuiming; Xu Tongwen . E-mail: twxu@ustc.edu.cn; Gong Ming; Xu Xiaolong

    2005-07-15

    A series of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO)-based organic-inorganic hybrid materials for anion exchange were prepared through sol-gel process of polymer precursors PPO-Si(OCH{sub 3}){sub 3}. PPO-Si(OCH{sub 3}){sub 3} were obtained from the reaction of bromomethylated PPO with 3-aminopropyl-trimethoxysilane (A1110). These polymer precursors then underwent hydrolysis and condensation with additional A1110 to generate hybrid materials. The reaction to produce polymer precursors was identified by FTIR; while FTIR, TGA, XRD, SEM, as well as conventional ion exchange capacity (IEC) measurements were conducted for the structures and properties of the prepared hybrids. TGA results show that this series of hybrid materials possess high thermal stability; XRD and SEM indicate that the prepared hybrid materials are amorphous and the inorganic and organic contents show good compatibility if the ratio between them is proper. The IEC values of the hybrid materials due to the amine groups range from 1.13 mmol/gBPPO (material i) to 4.80 mmol/gBPPO (material iv)

  7. Visible-Light-Induced Olefin Activation Using 3D Aromatic Boron-Rich Cluster Photooxidants.

    PubMed

    Messina, Marco S; Axtell, Jonathan C; Wang, Yiqun; Chong, Paul; Wixtrom, Alex I; Kirlikovali, Kent O; Upton, Brianna M; Hunter, Bryan M; Shafaat, Oliver S; Khan, Saeed I; Winkler, Jay R; Gray, Harry B; Alexandrova, Anastassia N; Maynard, Heather D; Spokoyny, Alexander M

    2016-06-08

    We report a discovery that perfunctionalized icosahedral dodecaborate clusters of the type B12(OCH2Ar)12 (Ar = Ph or C6F5) can undergo photo-excitation with visible light, leading to a new class of metal-free photooxidants. Excitation in these species occurs as a result of the charge transfer between low-lying orbitals located on the benzyl substituents and an unoccupied orbital delocalized throughout the boron cluster core. Here we show how these species, photo-excited with a benchtop blue LED source, can exhibit excited-state reduction potentials as high as 3 V and can participate in electron-transfer processes with a broad range of styrene monomers, initiating their polymerization. Initiation is observed in cases of both electron-rich and electron-deficient styrene monomers at cluster loadings as low as 0.005 mol%. Furthermore, photo-excitation of B12(OCH2C6F5)12 in the presence of a less activated olefin such as isobutylene results in the production of highly branched poly(isobutylene). This work introduces a new class of air-stable, metal-free photo-redox reagents capable of mediating chemical transformations.

  8. A Theoretical Study of Methanol Oxidation Catalyzed by Isolated Vanadia Clusters Supported on the (101) Surface of Anatase

    SciTech Connect

    Shapovalov, Vladimir; Fievez, Tim; Bell, Alexis T.

    2012-08-13

    A theoretical model has been developed for describing isolated vanadate species dispersed on the (101) surface of anatase that takes into account the equilibration of the supported species with gas-phase oxygen. The lowest energy of the combined solid and gas phases identifies the VOx species with the optimal structure and composition. This model of VOx species supported on the surface of anatase is then used to analyze the reaction path for methanol oxidation to formaldehyde. The chemisorption of methanol is found to proceed preferentially by addition across a V-O-Ti bond to form V-OCH3 and Ti-OH species. The rate-limiting step for the formation of formaldehyde takes place via the transfer of a hydrogen atom from V-OCH3 bound to an oxygen atom bridging two Ti atoms, i.e., a Ti-O-Ti group located adjacent to the supported vanadate species. This step is found to have the lowest apparent activation energy of all pathways explored for the formation of formaldehyde.

  9. On the competition between hydrogen abstraction versus C-O bond fission in initiating dimethyl ether combustion

    SciTech Connect

    Francisco, J.

    1999-07-01

    There has been a growing interest in the potential use of dimethyl ether (DME) as a diesel fuel in compression ignition engines. There are two initiation steps involved in the combustion of DME, one involving C-O bond fission and the other involving hydrogen abstraction by molecular oxygen. The kinetics and thermodynamics of C-O bond fission were explored computationally in a previous paper. The present paper addresses the competing process--hydrogen abstraction by molecular oxygen. Ab initio molecular orbital calculations are used to study the structures and energetics of the reactants, products, and the transition state for the CH{sub 3}OCH{sub 3} + O{sub 2} reaction. The calculations predict a barrier for hydrogen abstraction from CH{sub 3}OCH{sub 3} by O{sub 2} of 47.4 kcal/mol. This is lower than the barrier height for C-O bond fission previously calculated to be 81.1 kcal/mol. The results support values used in current models for the combustion of DME. Moreover, an examination of rates for C-O bond fission versus hydrogen abstraction by O{sub 2} suggests that the bimolecular process is the dominant pathway.

  10. Atmospheric and combustion chemistry of dimethyl ether

    SciTech Connect

    Nielsen, O.J.; Egsgaard, H.; Larsen, E.; Sehested, J.; Wallington, T.J.

    1997-12-31

    It has been demonstrated that dimethyl ether (DME) is an ideal diesel fuel alternative. DME, CH{sub 3}OCH{sub 3}, combines good fuel properties with low exhaust emissions and low combustion noise. Large scale production of this fuel can take place using a single step catalytic process converting CH{sub 4} to DME. The fate of DME in the atmosphere has previously been studied. The atmospheric degradation is initiated by the reaction with hydroxyl radicals, which is also a common feature of combustion processes. Spectrokinetic investigations and product analysis were used to demonstrate that the intermediate oxy radical, CH{sub 3}OCH{sub 2}O, exhibits a novel reaction pathway of hydrogen atom ejection. The application of tandem mass spectrometry to chemi-ions based on supersonic molecular beam sampling has recently been demonstrated. The highly reactive ionic intermediates are sampled directly from the flame and identified by collision activation mass spectrometry and ion-molecule reactions. The mass spectrum reflects the distribution of the intermediates in the flame. The atmospheric degradation of DME as well as the unique fuel properties of a oxygen containing compound will be discussed.

  11. Competing Noncovalent Host-guest Interactions and H/D Exchange: Reactions of Benzyloxycarbonyl-Proline Glycine Dipeptide Variants with ND3

    NASA Astrophysics Data System (ADS)

    Miladi, Mahsan; Olaitan, Abayomi D.; Zekavat, Behrooz; Solouki, Touradj

    2015-11-01

    A combination of density functional theory calculations, hydrogen/deuterium exchange (HDX) reactions, ion mobility-mass spectrometry, and isotope labeling tandem mass spectrometry was used to study gas-phase "host-guest" type interactions of a benzyloxycarbonyl (Z)-capped proline (P) glycine (G) model dipeptide (i.e., Z-PG) and its various structural analogues with ND3. It is shown that in a solvent-free environment, structural differences between protonated and alkali metal ion (Na+, K+, or Cs+)-complexed species of Z-PG affect ND3 adduct formation. Specifically, [Z-PG + H]+ and [Z-PG-OCH3 + H]+ formed gas-phase ND3 adducts ([Z-PG (or Z-PG-OCH3) + H + ND3]+) but no ND3 adducts were observed for [Z-PG + alkali metal]+ or [Z-PG + H - CO2]+. Experimentally measured and theoretically calculated collision cross sections (CCSs) of protonated and alkali metal ion-complexed Z-PG species showed similar trends that agreed with the observed structural differences from molecular modeling results. Moreover, results from theoretical ND3 affinity calculations were consistent with experimental HDX observations, indicating a more stable ND3 adduct for [Z-PG + H]+ compared to [Z-PG + alkali metal]+ species. Molecular modeling and experimental MS results for [Z-PG + H]+ and [Z-PG + alkali metal]+ suggest that optimized cation-π and hydrogen bonding interactions of carbonyl groups in final products are important for ND3 adduct formation.

  12. Design of peptides with α,β-dehydro-residues: syntheses, crystal structures and molecular conformations of two ΔPhe-Trp containing peptides

    NASA Astrophysics Data System (ADS)

    Vijayaraghavan, R.; Makker, J.; Kumar, P.; Dey, S.; Singh, T. P.

    2003-06-01

    The ΔPhe-Trp is a newly designed moiety that was found inducing a unique conformation in peptides. The peptides Boc-L-Val-ΔPhe-L-Trp-OCH 3 (I) and Boc-L-Leu-ΔPhe-L-Trp-OCH 3 (II) were synthesized by azlactone method in solution phase. The peptide (I) was crystallized from its solution in ethanol-water mixture in orthorhombic space group P2 12 12 1 with a=10.663(3) Å, b=11.204(3) Å, c=26.516(10) Å and peptide (II) was crystallized from its solution in acetone in a monoclinic space group P2 1 with a=9.354(1)Å, b=11.218(4)Å, c=15.633(1)Å and β=101.83(1)°. The structures were determined by direct methods. Peptide (I) was refined to an R value of 0.059 for 1554 observed reflections [ I≥2 σ (I)] and peptide (II) was refined to an R value of 0.043 for 2920 observed reflections [ I≥2 σ (I)]. The structures of peptides (I) and (II) were found to be identical. They formed an unusual type VIa β-turn conformation which is observed for the first time with a ΔPhe residue at ( i+2) position indicating a unique influence of ΔPhe-Trp moiety in inducing a reproducible new structure in peptides.

  13. OH Production from Reactions of Organic Peroxy Radicals with HO2 : Recent Studies on Ether-Derived Peroxy Radicals

    NASA Astrophysics Data System (ADS)

    Orlando, J. J.; Tyndall, G. S.; Kegley Owen, C. S.; Reynoldson, N.

    2013-12-01

    There is now ample evidence supporting significant formation of OH radicals in the reaction of HO2 with certain organic peroxy radicals (RO2). These reaction channels serve to promote radical propagation, and thus have the potential to alter HOx budgets and partitioning and hence tropospheric oxidative capacity. While much focus has been placed on OH production from reactions involving carbonyl-containing RO2 species, it is also the case that other oxygen- substituted peroxy species (e.g., CH3OCH2OO, HOCH2OO) likely generate OH in their reactions with HO2 (see ref. 1 and refs therein). In this work, the Cl-atom-initiated oxidation of two ethers, diethyl and diisopropyl ether, is investigated over ranges of conditions in an environmental chamber, using both FTIR and GC-FID methods for product quantification. Preliminary analysis suggests that significant OH production is occurring in the reaction of HO2 with CH3CH2OCH(OO)CH3, and also provides evidence for a rapid unimolecular reaction of diisopropyl ether-derived peroxy radicals. Details of these and other results will be described. 1. Orlando, J. J., and G. S. Tyndall, 2012: Laboratory studies of organic peroxy radical chemistry: an overview with emphasis on recent issues of atmospheric significance, Chemical Society Reviews, 41, 6294-6317, doi: 10.1039/C2CS35166H.

  14. Intramolecular Oxidative O-Demethylation of an Oxoferryl Porphyrin Complexed with a Per-O-methylated β-Cyclodextrin Dimer.

    PubMed

    Kitagishi, Hiroaki; Kurosawa, Shun; Kano, Koji

    2016-11-22

    The intramolecular oxidation of ROCH3 to ROCH2 OH, where the latter compound spontaneously decomposed to ROH and HCHO, was observed during the reaction of the supramolecular complex (met-hemoCD3) with cumene hydroperoxide in aqueous solution. Met-hemoCD3 is composed of meso-tetrakis(4-sulfonatophenyl)porphinatoiron(III) (Fe(III) TPPS) and a per-O-methylated β-cyclodextrin dimer having an -OCH2 PyCH2 O- linker (Py=pyridine-3,5-diyl). The O=Fe(IV) TPPS complex was formed by the reaction of met-hemoCD3 with cumene hydroperoxide, and isolated by gel-filtration chromatography. Although the isolated O=Fe(IV) TPPS complex in the cyclodextrin cage was stable in aqueous solution at 25 °C, it was gradually converted to Fe(II) TPPS (t1/2 =7.6 h). This conversion was accompanied by oxidative O-demethylation of an OCH3 group in the cyclodextrin dimer. The results indicated that hydrogen abstraction by O=Fe(IV) TPPS from ROCH3 yields HO-Fe(III) TPPS and ROCH2(.) . This was followed by radical coupling to afford Fe(II) TPPS and ROCH2 OH. The hemiacetal (ROCH2 OH) immediately decomposed to ROH and HCHO. This study revealed the ability of oxoferryl porphyrin to induce two-electron oxidation.

  15. Hydrogen production by coupled catalytic partial oxidation and steam methane reforming at elevated pressure and temperature

    NASA Astrophysics Data System (ADS)

    Chen, Luwei; Hong, Qi; Lin, Jianyi; Dautzenberg, F. M.

    Hydrogen production by coupled catalytic partial oxidation (CPO) and steam methane reforming of methane (OSMR) at industrial conditions (high temperatures and pressures) have been studied over supported 1 wt.% NiB catalysts. Mixture of air/CH 4/H 2O was applied as the feed. The effects of O 2:CH 4 ratio, H 2O:CH 4 ratio and the gas hourly space velocity (GHSV) on oxy-steam reforming (OSRM) were also studied. Results indicate that CH 4 conversion increases significantly with increasing O 2:CH 4 or H 2O:CH 4 ratio. However, the hydrogen mole fraction goes through a maximum, depending on reaction conditions, e.g., pressure, temperature and the feed gases ratios. Carbon deposition on the catalysts has been greatly decreased after steam addition. The supported 1 wt.% NiB catalysts exhibit high stability with 85% methane conversion at 15 bar and 800 °C during 70 h time-on-stream reaction (CH 4:O 2:H 2O:N 2 = 1:0.5:1:1.887). The thermal efficiency was increased from 35.8% by CPO (without steam) to 55.6%. The presented data would be useful references for further design of enlarged scale hydrogen production system.

  16. Theoretical and experimental study of methane steam reforming reactions over nickel catalyst

    NASA Astrophysics Data System (ADS)

    Pistonesi, C.; Juan, A.; Irigoyen, B.; Amadeo, N.

    2007-02-01

    In this work we perform DFT theoretical calculations of methane and steam interactions on Ni(1 1 1) surface. The calculations allow us to improve our understanding of the competition between these reactants by catalytic sites in methane steam reforming (MSR) process. For this purpose we compare theoretical results with kinetic measurements of MSR on a Ni(II)-Al(III) catalyst prepared from lamellar double hydroxides as precursor. This comparison shows that, for low H 2O/CH 4 ratios methane and water intermediate species adsorb on different catalytic sites. While CHO species adsorbs on top of Ni atom, OH one occupies preferentially a tri-coordinate surface site. On the other hand, for high H 2O/CH 4 ratios a competency between these species by Ni sites would establish, diminishing methane conversion. In addition competition between methane and steam for Ni sites would lead to a decrease in CO production. Nevertheless, intermediate species adsorbed on different active sites would produce CO 2, whatever the steam/methane ratio. Thus, it would be optimum steam concentration in hydrocarbon feed and active sites distribution on catalyst surface, which could maximize H 2 production and minimize CO selectivity. The theoretical findings agree with kinetic measurements, which show that maximum methane conversion depends on steam partial pressure in the feed; whereas always, selectivity to CO 2 increases and to CO diminishes.

  17. One-pot solvothermal synthesis of a well-ordered layered sodium aluminoalcoholate complex: a useful precursor for the preparation of porous Al2O3 particles

    SciTech Connect

    Li, XS; Michaelis, VK; Ong, TC; Smith, SJ; McKay, I; Muller, P; Griffin, RG; Wang, EN

    2014-01-01

    One-pot solvothermal synthesis of a robust tetranuclear sodium hexakis(glycolato)tris(methanolato)aluminate complex Na-3[Al-4(OCH3)(3)(OCH2CH2O)(6)] via a modified yet rigorous base-catalyzed transesterification mechanism is presented here. Single crystal X-ray diffraction (SCXRD) studies indicate that this unique Al complex contains three pentacoordinate Al3+ ions, each bound to two bidentate ethylene glycolate chelators and one monodentate methanolate ligand. The remaining fourth Al3+ ion is octahedrally coordinated to one oxygen atom from each of the six surrounding glycolate chelators, effectively stitching the three pentacoordinate Al moieties together into a novel tetranuclear Al complex. This aluminate complex is periodically self-assembled into well-ordered layers normal to the [110] axis with the intra-/inter-layer bonding involving extensive ionic bonds from the three charge-counterbalancing Na+ cations rather than the more typical hydrogen bonding interactions as a result of fewer free hydroxyl groups present in its structure. It can also serve as a valuable precursor toward the facile synthesis of high-surface-area alumina powders using a very efficient rapid pyrolysis technique.

  18. Three-component one-pot synthesis of novel pyrido[2,3-d]pyrimidine indole substituted derivatives and DFT analysis

    NASA Astrophysics Data System (ADS)

    Rangel, Jovanni; Díaz-Uribe, Carlos; Rodriguez-Serrano, Angela; Zarate, Ximena; Serge, York; Vallejo, William; Nogueras, Manuel; Trilleras, Jorge; Quiroga, Jairo; Tatchen, Jörg; Cobo, Justo

    2017-06-01

    Pyridopyrimidines are heterocyclic aromatic compounds known by their antibacterial and medicinal properties. In this work, a series of pyrido[2,3-d]pyrimidine indole derivatives were synthesized by three-component one pot cyclocondensation Michael reaction between 2,6-diaminopirimidin-4(3H)-one, 3-(2-cyanoacetyl)indole and aromatic aldehydes in boiling acetic acid as solvent. The compounds differ with respect to the substituents of the aromatic aldehyde which are comprised by -C6H5, -4-ClC6H4, -4-NO2C6H4, -3,4-OCH2OC6H3, -3-OCH3,4-OH,5-NO2C6H2, and -3,4,5-tri-H3COC6H2, respectively. The compounds were synthesized with reasonable yields. They were characterized by and IR, mass, and NMR spectrometry. The protocol employed offers the convenient advantages of a one-step synthesis, considerable savings of solvents, and easy isolation of reaction products. In addition, DFT and TD-DFT quantum chemical calculations were used to characterize the geometry and electronic structure of the compounds.

  19. The New World whirligig beetles of the genus Dineutus Macleay, 1825 (Coleoptera, Gyrinidae, Gyrininae, Dineutini).

    PubMed

    Gustafson, Grey T; Miller, Kelly B

    2015-01-01

    All New World members of the whirligig beetle genus Dineutus Macleay, 1825 are treated. The New World Dineutus are found to be composed of 18 species and 6 subspecies: one species, Dineutusmexicanus Ochs, 1925, stat. n. is elevated from subspecies to species rank, and the subspecies Dineutuscarolinusmutchleri Ochs, 1925, syn. n. is synonymized here with the typical form. Lectotypes are designated for Dineutusdiscolor Aubé, 1838, Dineutesmetallicus Aubé, 1838, Dineutussolitarius Aubé, 1838, Dineutesanalis Régimbart, 1883, and Gyrinuslongimanus Olivier, 1795. Each taxonomic unit is provided with a taxonomic history, type locality, diagnosis, distribution, habitat information, and a discussion section. The aedeagus and male mesotarsal claws are illustrated, and dorsal and ventral habitus images of both sexes, for each species and subspecies are provided. General distribution maps are provided for all taxonimc units. A key to the genera of New World Gyrinidae, as well as all the New World Dineutus species is provided. General Dineutus anatomy as well as a clarification of homology and anatomical terms is included.

  20. Reactive Capture of Gold Nanoparticles by Strongly Physisorbed Monolayers on Graphite

    SciTech Connect

    Wei, Xiaoliang; Tong, Wenjun; Fidler, Vlastimil; Zimmt, Matthew B.

    2012-12-01

    Anthracene Diels Alder adducts (DAa) bearing two long side chains (H-(CH2)22O(CH2)6OCH2-) at the 1- and 5-positions form self-assembled monolayers (SAMs) at the phenyloctane - highly oriented pyrolytic graphite (HOPG) interface. The long DAa side chains promote strong physisorption of the monolayer to HOPG and maintain the monolayer morphology upon rinsing or incubation in ethanol and air-drying of the substrate. Incorporating a carboxylic acid group on the DAa core enables capture of 1 - 4 nm diameter gold nanoparticles (AuNP) provided (i) the monolayer containing DAa-carboxylic acids is treated with Cu2+ ions and (ii) the organic coating on the AuNP contains carboxylic acids (11-mercaptoundecanoic acid, MUA-AuNP). AuNP capture by the monolayer proceeds with formation of Cu2+ - carboxylate coordination complexes. The captured AuNP appear as mono- and multi-layered clusters at high coverage on HOPG. The surface density of the captured AuNPs can be adjusted from AuNP multi-layers to isolated AuNPs by varying incubation times, MUA-AuNP concentration, the number density of carboxylic acids in the monolayer, the number of MUA per AuNP, and the post-incubation treatments.

  1. Ab Initio Investigation of Polyethylene Glycol Coating of TiO2 Surfaces

    PubMed Central

    2016-01-01

    In biomedical applications, TiO2 nanoparticles are generally coated with polymers to prevent agglomeration, improve biocompatibility, and reduce cytotoxicity. Although the synthesis processes of such composite compounds are well established, there is still a substantial lack of information on the nature of the interaction between the titania surface and the organic macromolecules. In this work, the adsorption of polyethylene glycol (PEG) on the TiO2 (101) anatase surface is modeled by means of dispersion-corrected density functional theory (DFT-D2) calculations. The two extreme limits of an infinite PEG polymer [−(OCH2CH2)n], on one side, and of a short PEG dimer molecule [H(OCH2CH2)2OH], on the other, are analyzed. Many different molecular configurations and modes of adsorption are compared at increasing surface coverage densities. At low and medium coverage, PEG prefers to lay down on the surface, while at full coverage, the adsorption is maximized when PEG molecules bind perpendicularly to the surface and interact with each other through lateral dispersions, following a mushroom to brush transition. Finally, we also consider the adsorption of competing water molecules at different coverage densities, assessing whether PEG would remain bonded to the surface or desorb in the presence of the aqueous solvent. PMID:28058086

  2. Electrochemically assisted fabrication of size-exclusion films of organically modified silica and application to the voltammetry of phospholipids

    PubMed Central

    Mehdi, B. Layla; Rutkowska, Iwona A.; Kulesza, Pawel J.

    2013-01-01

    Modification of electrodes with nm-scale organically modified silica films with pores diameters controlled at 10- and 50-nm is described. An oxidation catalyst, mixed-valence ruthenium oxide with cyano crosslinks or gold nanoparticles protected by dirhodium-substituted phosophomolybdate (AuNP-Rh2PMo11), was immobilized in the pores. These systems comprise size-exclusion films at which the biological compounds, phosphatidylcholine and cardiolipin, were electrocatalytically oxidized without interference from surface-active concomitants such as bovine serum albumin. 10-nm pores were obtained by adding generation-4 poly(amidoamine) dendrimer, G4-PAMAM, to a (CH3)3SiOCH3 sol. 50-nm pores were obtained by modifying a glassy carbon electrode (GC) with a sub-monolayer film of aminopropyltriethoxylsilane, attaching 50-nm diameter poly(styrene sulfonate), PSS, spheres to the protonated amine, transferring this electrode to a (CH3)3SiOCH3 sol, and electrochemically generating hydronium at uncoated GC sites, which catalyzed ormosil growth around the PSS. Voltammetry of Fe(CN)63− and Ru(NH3)63+ demonstrated the absence of residual charge after removal of the templating agents. With the 50-nm system, the pore structure was sufficiently defined to use layer-by-layer electrostatic assembly of AuNP-Rh2PMo11 therein. Flow injection amperometry of phosphatidylcholine and cardiolipin demonstrated analytical utility of these electrodes. PMID:23935394

  3. The New World whirligig beetles of the genus Dineutus Macleay, 1825 (Coleoptera, Gyrinidae, Gyrininae, Dineutini)

    PubMed Central

    Gustafson, Grey T.; Miller, Kelly B.

    2015-01-01

    Abstract All New World members of the whirligig beetle genus Dineutus Macleay, 1825 are treated. The New World Dineutus are found to be composed of 18 species and 6 subspecies: one species, Dineutus mexicanus Ochs, 1925, stat. n. is elevated from subspecies to species rank, and the subspecies Dineutus carolinus mutchleri Ochs, 1925, syn. n. is synonymized here with the typical form. Lectotypes are designated for Dineutus discolor Aubé, 1838, Dineutes metallicus Aubé, 1838, Dineutus solitarius Aubé, 1838, Dineutes analis Régimbart, 1883, and Gyrinus longimanus Olivier, 1795. Each taxonomic unit is provided with a taxonomic history, type locality, diagnosis, distribution, habitat information, and a discussion section. The aedeagus and male mesotarsal claws are illustrated, and dorsal and ventral habitus images of both sexes, for each species and subspecies are provided. General distribution maps are provided for all taxonimc units. A key to the genera of New World Gyrinidae, as well as all the New World Dineutus species is provided. General Dineutus anatomy as well as a clarification of homology and anatomical terms is included. PMID:25685002

  4. T helper type 2-polarized invariant natural killer T cells reduce disease severity in acute intra-abdominal sepsis.

    PubMed

    Anantha, R V; Mazzuca, D M; Xu, S X; Porcelli, S A; Fraser, D D; Martin, C M; Welch, I; Mele, T; Haeryfar, S M M; McCormick, J K

    2014-11-01

    Sepsis is characterized by a severe systemic inflammatory response to infection that is associated with high morbidity and mortality despite optimal care. Invariant natural killer T (iNK T) cells are potent regulatory lymphocytes that can produce pro- and/or anti-inflammatory cytokines, thus shaping the course and nature of immune responses; however, little is known about their role in sepsis. We demonstrate here that patients with sepsis/severe sepsis have significantly elevated proportions of iNK T cells in their peripheral blood (as a percentage of their circulating T cells) compared to non-septic patients. We therefore investigated the role of iNK T cells in a mouse model of intra-abdominal sepsis (IAS). Our data show that iNK T cells are pathogenic in IAS, and that T helper type 2 (Th2) polarization of iNK T cells using the synthetic glycolipid OCH significantly reduces mortality from IAS. This reduction in mortality is associated with the systemic elevation of the anti-inflammatory cytokine interleukin (IL)-13 and reduction of several proinflammatory cytokines within the spleen, notably interleukin (IL)-17. Finally, we show that treatment of sepsis with OCH in mice is accompanied by significantly reduced apoptosis of splenic T and B lymphocytes and macrophages, but not natural killer cells. We propose that modulation of iNK T cell responses towards a Th2 phenotype may be an effective therapeutic strategy in early sepsis.

  5. Theoretical study of the O···Cl interaction in fluorinated dimethyl ethers complexed with a Cl atom: is it through a two-center-three-electron bond?

    PubMed

    Zeegers-Huyskens, Therese; Lily, Makroni; Sutradhar, Dipankar; Chandra, Asit K

    2013-08-22

    Theoretical investigations are carried out on the interaction between fluorinated dimethyl ethers (FDME, nF = 0-4) and the Cl atom. Short intermolecular O···Cl distances between 2.401 and 2.938 Å reveal the formation of a new class of complexes. The interaction energies calculated with the G2(MP2) method range between -9.1 (nF = 4) and -26.0 (nF = 0) kJ/mol. The charge transfer occurring from the ethers to atomic Cl is moderate and ranges between 0.012 e (nF = 4) to 0.188 e (nF = 0). The binding energies are linearly related to the proton affinity, to the charge transfer (CT) occurring in the molecular system and inversely proportional to the ionization potential and electron affinity (IP-EA) values. The CT and spin density data indicate substantial two-center-three-electron O···Cl interaction in CH3OCH3···Cl and CH3OCH2F···Cl systems, whereas for highly fluorinated ethers the interaction is predominantly electrostatic in nature. The formation of the complex results in a contraction of the CH bonds, especially in the gauche position. The blue shifts of the C-H stretching vibrations calculated in the partially deuterated isotopomers range between 2 and 54 cm(-1) and are correlated to the variation of the CH distances.

  6. Improving the thermostability of a methyl parathion hydrolase by adding the ionic bond on protein surface.

    PubMed

    Su, Yidan; Tian, Jian; Wang, Ping; Chu, Xiaoyu; Liu, Guoan; Wu, Ningfeng; Fan, Yunliu

    2011-10-01

    The thermostability of the methyl parathion hydrolase (MPH_OCH) from Ochrobactrum sp. M231 was improved using site-directed mutagenesis. Two prolines (Pro76 and Pro78) located on the protein surface were selected for mutations after inspection of the sequence alignment of MPH_OCH and OPHC2, a thermostable organophosphorus hydrolase from Pseudomonas pseudoalcaligenes C2-1. The temperature of the double-point mutant (P76D/P78K) at which the mutant lost 50% of its activity (T50) was approximately 68 °C, which is higher than that of WT enzyme (64 °C), P76D (67 °C), and P78K (59 °C). Structural analysis of P76D/P78K indicated that the substituted residues (Asp76 and Lys78) could generate an ionic bond and increase the structural electrostatic energy, which could then increase the stability of the protein. These results also suggest that the thermal stability of proteins could be improved by adding the ionic bond on protein surface.

  7. Non-strinking siloxane polymers

    DOEpatents

    Loy, Douglas A.; Rahimian, Kamyar

    2001-01-01

    Cross-linked polymers formed by ring-opening polymerization of a precursor monomer of the general formula R[CH.sub.2 CH(Si(CH.sub.3).sub.2).sub.2 O].sub.2, where R is a phenyl group or an alkyl group having at least two carbon atoms. A cross-linked polymer is synthesized by mixing the monomer with a co-monomer of the general formula CH.sub.2 CHR.sup.2 (SiMe.sub.2).sub.2 O in the presence of an anionic base to form a cross-linked polymer of recurring units of the general formula R(Me.sub.2 SiOCH.sub.2 CHSiMe.sub.2).sub.2 [CH.sub.2 CHR.sup.2 (SiMe.sub.2).sub.2 O].sub.n, where R.sup.2 is hydrogen, phenyl, ethyl, propyl or butyl. If the precursor monomer is a liquid, the polymer can be directly synthesized in the presence of an anionic base to a cross-linked polymer containing recurring units of the general formula R(Me.sub.2 SiOCH.sub.2 CHSiMe.sub.2).sub.2. The polymers have approximately less than 1% porosity and are thermally stable at temperatures up to approximately 500.degree. C. The conversion to the cross-linked polymer occurs by ring opening polymerization and results in shrinkage of less than approximately 5% by volume.

  8. One-pot Solvothermal Synthesis of Well-ordered Layered Sodium Aluminoalcoholate Complex: A Useful Precursor for the Preparation of Porous Al2O3 Particles†

    PubMed Central

    Li, Xiansen; Michaelis, Vladimir K.; Ong, Ta-Chung; Smith, Stacey J.; McKay, Ian; Müller, Peter; Griffin, Robert G.; Wang, Evelyn N.

    2014-01-01

    One-pot solvothermal synthesis of a robust tetranuclear sodium hexakis(glycolato)tris(methanolato)aluminate complex Na3[Al4(OCH3)3(OCH2CH2O)6] via a modified yet rigorous base-catalyzed transesterification mechanism is presented here. Single crystal X-ray diffraction (SCXRD) studies indicate that this unique Al complex contains three penta-coordinate Al3+ ions, each bound to two bidentate ethylene glycolate chelators and one monodentate methanolate ligand. The remaining fourth Al3+ ion is octahedrally coordinated to one oxygen atom from each of the six surrounding glycolate chelators, effectively stitching the three penta-coordinate Al moieties together into a novel tetranuclear Al complex. This aluminate complex is periodically self-assembled into well-ordered layers normal to the [110] axis with the intra-/inter-layer bindings involving extensive ionic bonds from the three charge-counterbalancing Na+ cations rather than the more typical hydrogen bonding interactions as a result of the fewer free hydroxyl groups present in its structure. It can also serve as a valuable precursor toward the facile synthesis of high-surface-area alumina powders using a very efficient rapid pyrolysis technique. PMID:24817826

  9. Fluorinated microemulsions: A study of the phase behavior and structure

    SciTech Connect

    LoNostro, P.; Choi, S.M.; Chen, S.H.; Ku, C.Y.

    1999-06-24

    Fluorinated surfactants have been studied for their peculiar property to form micellar aggregates in water and oils (hydrocarbons or fluorocarbons) and to produce stable microemulsions. Because of their capacity to dissolve large amounts of gases (such as oxygen and carbon dioxide) and for their characteristic physicochemical properties, fluorocarbons have been tested for specific medical purposes, and their microemulsions are among the most promising candidates for the production of suitable blood substitutes and other biocompatible fluids. The authors have synthesized a new partially fluorinated nonionic surfactant, namely, F(CF{sub 2}){sub 7}-CO-(OCH{sub 2}CH{sub 2}){sub 7.2}OCH{sub 3} (I), that forms stable microemulsions with water and perfluorocarbons such as perfluorooctane (PFO). In this paper the authors describe for the first time the phase behaviors of perfluorooctanoic acid (PFOA) in water/PFH and in water/PFO, and that of ester I in water/PFO. Small-angle neutron-scattering (SANS) experiments provide a detailed description of the microstructure of the H{sub 2}O/PFO/PFOA ternary system.

  10. Immobilization of nanobeads on a surface to control the size, shape and distribution of pores in electrochemically generated sol-gel films

    PubMed Central

    Ciabocco, Michela; Berrettoni, Mario; Zamponi, Silvia

    2015-01-01

    Electrochemically assisted deposition of an ormosil film at a potential where hydrogen ion is generated as the catalyst yields insulating films on electrodes. When the base electrode is modified with 20-nm poly(styrene sulfonate), PSS, beads bound to the surface with 3-aminopropyltriethoxysilane (APTES) and using (CH3)3SiOCH3 as the precursor, the resulting film of organically modified silica (ormosil) has cylindrical channels that reflect both the diameter of the PSS and the distribution of the APTES-PSS on the electrode. At an electrode modified by a 20-min immersion in 0.5 mmol dm-3 APTES followed by a 30-s immersion in PSS, a 20-min electrolysis at 1.5 V in acidified (CH3)3SiOCH3 resulted in an ormosil film with 20-nm pores separated by 100 nm. Cyclic voltammetry of Ru(CN)64- at scan rates above 5 mVs-1 yielded currents controlled primarily by linear diffusion. Below 5 mVs-1, convection rather than the expected factor, radial diffusion, apparently limited the current. PMID:26167128

  11. The adsorption and reaction of ethylene glycol and 1,2-propanediol on Pd(111): A TPD and HREELS study

    NASA Astrophysics Data System (ADS)

    Griffin, Michael B.; Jorgensen, Erica L.; Medlin, J. Will

    2010-09-01

    The reactions of ethylene glycol and 1,2-propanediol have been studied on Pd(111) using temperature programmed desorption (TPD) and high resolution electron energy loss spectroscopy (HREELS). Both molecules initially decompose through O-H activation, forming ethylenedioxy (-OCH 2CH 2O-) and 1,2-propanedioxy (-OCH 2CH(CH 3)O-) surface intermediates. For ethylene glycol, increases in thermal energy lead to dehydrogenation and formation of carbonyl species at both oxygen atoms. The resulting glyoxal (O═CHCH═O) either desorbs molecularly or reacts through one of two competing pathways. The favored pathway proceeds via C-C bond scission, dehydrogenation, and decarbonylation to form carbon monoxide and hydrogen. In a minor pathway, small amounts of glyoxal undergo C-O bond scission and recombination with surface hydrogen to form ethylene and water. The same reaction mechanism occurs for 1,2-propanediol after methyl elimination and formation of glyoxal. However, this is accompanied by a minor pathway involving a methylglyoxal (O=CHC(CH 3)=O) intermediate. The prevalence of the dehydrogenation/decarbonylation pathway in the current work is consistent with the high selectivity for C-C scission in the aqueous phase reforming of polyols on supported Pd catalysts.

  12. Analysis of the nucleus-encoded and chloroplast-targeted rieske protein by classic and site-directed mutagenesis of Chlamydomonas.

    PubMed Central

    de Vitry, C; Finazzi, G; Baymann, F; Kallas, T

    1999-01-01

    Three mutants of the alga Chlamydomonas reinhardtii affected in the nuclear PETC gene encoding the Rieske iron-sulfur protein 2Fe-2S subunit of the chloroplast cytochrome b(6)f complex have been characterized. One has a stable deletion that eliminates the protein; two others carry substitutions Y87D and W163R that result in low accumulation of the protein. Attenuated expression of the stromal protease ClpP increases accumulation and assembly into b(6)f complexes of the Y87D and W163R mutant Rieske proteins in quantities sufficient for analysis. Electron-transfer kinetics of these complexes were 10- to 20-fold slower than those for the wild type. The deletion mutant was used as a recipient for site-directed mutant petC alleles. Six glycine residues were replaced by alanine residues (6G6A) in the flexible hinge that is critical for domain movement; substitutions were created near the 2Fe-2S cluster (S128 and W163); and seven C-terminal residues were deleted (G171och). Although the 6G6A and G171och mutations affect highly conserved segments in the chloroplast Rieske protein, photosynthesis in the mutants was similar to that of the wild type. These results establish the basis for mutational analysis of the nuclear-encoded and chloroplast-targeted Rieske protein of photosynthesis. PMID:10521530

  13. Analysis of the nucleus-encoded and chloroplast-targeted rieske protein by classic and site-directed mutagenesis of Chlamydomonas.

    PubMed

    de Vitry, C; Finazzi, G; Baymann, F; Kallas, T

    1999-10-01

    Three mutants of the alga Chlamydomonas reinhardtii affected in the nuclear PETC gene encoding the Rieske iron-sulfur protein 2Fe-2S subunit of the chloroplast cytochrome b(6)f complex have been characterized. One has a stable deletion that eliminates the protein; two others carry substitutions Y87D and W163R that result in low accumulation of the protein. Attenuated expression of the stromal protease ClpP increases accumulation and assembly into b(6)f complexes of the Y87D and W163R mutant Rieske proteins in quantities sufficient for analysis. Electron-transfer kinetics of these complexes were 10- to 20-fold slower than those for the wild type. The deletion mutant was used as a recipient for site-directed mutant petC alleles. Six glycine residues were replaced by alanine residues (6G6A) in the flexible hinge that is critical for domain movement; substitutions were created near the 2Fe-2S cluster (S128 and W163); and seven C-terminal residues were deleted (G171och). Although the 6G6A and G171och mutations affect highly conserved segments in the chloroplast Rieske protein, photosynthesis in the mutants was similar to that of the wild type. These results establish the basis for mutational analysis of the nuclear-encoded and chloroplast-targeted Rieske protein of photosynthesis.

  14. Trifunctional metal ion-catalyzed solvolysis: Cu(II)-promoted methanolysis of N,N-bis(2-picolyl) benzamides involves unusual Lewis acid activation of substrate, delivery of coordinated nucleophile, powerful assistance of the leaving group departure.

    PubMed

    Raycroft, Mark A R; Maxwell, Christopher I; Oldham, Robyn A A; Andrea, Areen Saffouri; Neverov, Alexei A; Brown, R Stan

    2012-10-01

    The methanolyses of Cu(II) complexes of a series of N,N-bis(2-picolyl) benzamides (4a-g) bearing substituents X on the aromatic ring were studied under (s)(s)pH-controlled conditions at 25 °C. The active form of the complexes at neutral (s)(s)pH has a stoichiometry of 4:Cu(II):((-)OCH(3))(HOCH(3)) and decomposes unimolecularly with a rate constant k(x). A Hammett plot of log(k(x)) vs σ(x) values has a ρ(x) of 0.80 ± 0.05. Solvent deuterium kinetic isotope effects of 1.12 and 1.20 were determined for decomposition of the 4-nitro and 4-methoxy derivatives, 4b:Cu(II):((-)OCH(3))(HOCH(3)) and 4g:Cu(II):((-)OCH(3))(HOCH(3)), in the plateau region of the (s)(s)pH/log(k(x)) profiles in both CH(3)OH and CH(3)OD. Activation parameters for decomposition of these complexes are ΔH(++) = 19.1 and 21.3 kcal mol(-1) respectively and ΔS(++) = -5.1 and -2 cal K(-1) mol(-1). Density functional theory (DFT) calculations for the reactions of the Cu(II):((-)OCH(3))(HOCH(3)) complexes of 4a,b and g (4a, X = 3,5-dinitro) were conducted to probe the relative transition state energies and geometries of the different states. The experimental and computational data support a mechanism where the metal ion is coordinated to the N,N-bis(2-picolyl) amide unit and positioned so that it permits delivery of a coordinated Cu(II):((-)OCH(3)) nucleophile to the C═O in the rate-limiting transition state (TS) of the reaction. This proceeds to a tetrahedral intermediate INT, occupying a shallow minimum on the free energy surface with the Cu(II) coordinated to both the methoxide and the amidic N. Breakdown of INT is a virtually barrierless process, involving a Cu(II)-assisted departure of the bis(2-picolyl)amide anion. The analysis of the data points to a trifunctional role for the metal ion in the solvolysis mechanism where it activates intramolecular nucleophilic attack on the C═O group by coordination to an amidic N in the first step of the reaction and subsequently assists leaving group

  15. Study of the photon-induced formation and subsequent desorption of CH3OH and H2CO in interstellar ice analogs

    NASA Astrophysics Data System (ADS)

    Martín-Doménech, R.; Muñoz Caro, G. M.; Cruz-Díaz, G. A.

    2016-05-01

    Context. Methanol and formaldehyde are two simple organic molecules that are ubiquitously detected in the interstellar medium, in both the solid and gaseous phases. An origin in the solid phase and a subsequent nonthermal desorption into the gas phase is often invoked to explain their abundances in some of the environments where they are found. Experimental simulations under astrophysically relevant conditions have been carried out in the past four decades in order to find a suitable mechanism for that process. Aims: In particular, photodesorption from pure methanol ice (and presumably from pure formaldehyde ice) has been found to be negligible in previous works, probably because both molecules are very readily dissociated by vacuum-UV photons. Therefore, we explore the in situ formation and subsequent photon-induced desorption of these species, studying the UV photoprocessing of pure ethanol ice, and a more realistic binary H2O:CH4 ice analog. Methods: Experimental simulations were performed in an ultra-high vacuum chamber. Pure ethanol and binary H2O:CH4 ice samples deposited onto an infrared transparent window at 8 K were UV-irradiated using a microwave-discharged hydrogen flow lamp. Evidence of photochemical production of these two species and subsequent UV-photon-induced desorption into the gas phase were searched for by means of a Fourier transform infrared spectrometer and a quadrupole mass spectrometer, respectively. After irradiation, ice samples were warmed up to room temperature until complete sublimation was attained for detection of volatile products. Results: Formation of CH3OH was only observed during photoprocessing of the H2O:CH4 ice analog, accounting for ~4% of the initial CH4 ice column density, but no photon-induced desorption was detected. Photochemical production of H2CO was observed in both series of experiments. Formation of formaldehyde accounted for ≤45% conversion of the initial ethanol ice, but it could not be quantified during

  16. The effect of a paramagnetic metal ion within a molecule: comparison of the structurally identical paramagnetic [3,3-Fe(1,2-C2B9H11)2]- with the diamagnetic [3,3-Co(1,2-C2B9H11)2]- sandwich complexes.

    PubMed

    Cioran, Ana M; Teixidor, Francesc; Viñas, Clara

    2015-02-14

    Derivatives of the ferrabisdicarbollide [3,3'-Fe(1,2-C(2)B(9)H(11))(2)](-) have been produced starting from the zwitterion [3,3'-Fe(8-(OCH(2)CH(2))(2)-1,2-C(2)B(9)H(10))(1',2'-C(2)B(9)H(11))], 1, upon reaction with nucleophiles: alkoxides, halides and hydrosulfide ions HS(-). The result has been the preparation of [3,3'-Fe(8-(OCH(2)CH(2))(2)R/X-1,2-C(2)B(9)H(10))(1',2'-C(2)B(9)H(11))] (R = OMe, [2](-); OEt, [3](-); OCH(2)CH(2)OCH(3), [4](-); and X = Cl, [5](-); Br, [6](-); I, [7](-); and SH, [8](-)). The reaction behavior of is comparable to the well-studied cobalt equivalent, [3,3'-Co(8-(OCH(2)CH(2))2-1,2-C(2)B(9)H(10))(1',2'-C(2)B(9)H(11))], and the yields and stability of the resulting complexes are similar. These results are relevant taking into account that [3,3'-Fe(1,2-C(2)B(9)H(11))(2))(-) is a paramagnetic anion. Implications of this are observed in the (11)B-, (1)H and (13)C NMR spectra of [3,3'-Co(1,2-C(2)B(9)H(11))(2)](-) and [3,3'-Fe(1,2-C(2)B(9)H(11))(2)](-) that having identical sandwich molecular structures and the same negative charge have absolutely different widths of the NMR field, between 15 and -25 ppm for [3,3'-Co(1,2-C(2)B(9)H(11))(2)](-) and in the range 150 to -550 ppm for [3,3'-Fe(1,2-C(2)B(9)H(11))(2)](-). The sharpness of both spectra is on the other hand comparable, although no B-H couplings are observed in the Fe metallacarborane or its derivatives. Remarkable is the comparative influence vs. [3,3'-Co(1,2-C(2)B(9)H(11))(2)](-) of replacing Co by Fe on the elements of the cluster layer nearest to the metal. The two equivalent C cluster (Cc) atoms are influenced at 36 840 Hz, the two equivalent B atoms that are adjacent to the two Cc are influenced at 38 157 Hz and the single B that is adjacent to the two B atoms is influenced at 44 062 Hz. Remarkable is the similar influence on B and on C, taking into account that the values have been obtained from two distinct NMR spectra of (11)B and (13)C. The {(11)B-(11)B} COSY NMR and {(1)H

  17. Redox-induced terpyridyl substitution in the Os(VI)-hydrazido complex, trans-[Os(VI)(tpy)(Cl)(2)(NN(CH(2))(4)O)](2+).

    PubMed

    Huynh, M H; Lee, D G; White, P S; Meyer, T J

    2001-07-30

    Reaction between the Os(VI)-hydrazido complex, trans-[Os(VI)(tpy)(Cl)(2)(NN(CH(2))(4)O)](2+) (tpy = 2,2':6',2"-terpyridine and O(CH(2))(4)N(-) = morpholide), and a series of N- or O-bases gives as products the substituted Os(VI)-hydrazido complexes, trans-[Os(VI)(4'-RNtpy)(Cl)(2)(NN(CH(2))(4)O)](2+) or trans-[Os(VI)(4'-ROtpy)(Cl)(2)(NN(CH(2))(4)O)](2+) (RN(-) = anilide (PhNH(-)); S,S-diphenyl sulfilimide (Ph(2)S=N(-)); benzophenone imide (Ph(2)C=N(-)); piperidide ((CH(2))(5)N(-)); morpholide (O(CH(2))(4)N(-)); ethylamide (EtNH(-)); diethylamide (Et(2)N(-)); and tert-butylamide (t-BuNH(-)) and RO(-) = tert-butoxide (t-BuO(-)) and acetate (MeCO(2)(-)). The rate law for the formation of the morpholide-substituted complex is first order in trans-[Os(VI)(tpy)(Cl)(2)(NN(CH(2))(4)O)](2+) and second order in morpholine with k(morp)(25 degrees C, CH(3)CN) = (2.15 +/- 0.04) x 10(6) M(-)(2) s(-)(1). Possible mechanisms are proposed for substitution at the 4'-position of the tpy ligand by the added nucleophiles. The key features of the suggested mechanisms are the extraordinary electron withdrawing effect of Os(VI) on tpy and the ability of the metal to undergo intramolecular Os(VI) to Os(IV) electron transfer. These substituted Os(VI)-hydrazido complexes can be electrochemically reduced to the corresponding Os(V), Os(IV), and Os(III) forms. The Os-N bond length of 1.778(4) A and Os-N-N angle of 172.5(4) degrees in trans-[Os(VI)(4'-O(CH(2))(4)Ntpy)(Cl)(2)(NN(CH(2))(4)O)](2+) are consistent with sp-hybridization of the alpha-nitrogen of the hydrazido ligand and an Os-N triple bond. The extensive ring substitution chemistry implied for the Os(VI)-hydrazido complexes is discussed.

  18. Theoretical investigation of the reaction of O({sup 3}P) with CH{sub 2}Cl

    SciTech Connect

    Wang, B.; Hou, H.; Gu, Y.

    1999-04-01

    Incineration is a broadly applicable and effective treatment method for the management of hazardous chlorinated hydrocarbons wastes in which the potentially toxic byproducts such as chlorinated methyl radicals are generated. The reaction of oxygen atom with chlorinated methyl radical has been studied using the G2MP2 level of theory. The computation reveals an association-elimination mechanism. The addition reaction of O({sup 3}P) with CH{sub 2}Cl proceeds to the formation of an energy-rich intermediate OCH{sub 2}Cl{sup *}. Four product channels of OCH{sub 2}Cl{sup *} are found: H + CHClO, Cl + CH{sub 2}O, CHClOH, and H{sub 2} + ClCO. The isomer CHClOH also has four product channels: H + CHClO, HCl + HCO, H{sub 2} + ClCO, and OH + CHCl. On the basis of this ab initio potential energy surface and the experimental rate constant at 297 K, the kinetics of the title reaction have been calculated by a loose transition-state model and RRKM theory. The overall rate constants can be fitted to a double-exponential formula {kappa}(T) = (1.51 {+-} 0.01) {times} 10{sup {minus}10} exp[(1.36 {+-} 0.01) kJ mol{sup {minus}1}/(RT)] + (2.23 {+-} 0.09) {times} 10{sup {minus}10} exp[({minus}27.48 {+-} 0.73) kJ mol{sup {minus}1}/(RT)] cm{sup 3} molecule{sup {minus}1}s{sup {minus}1} over the temperature range 250--2000 K. The energy-specific rate constants of the unimolecular decomposition of the activated adduct OCH{sub 2}Cl{sup *} are used to estimate the branching ratio. The production of H + CHClO is the major reaction channel, and the production of Cl + CH{sub 2}O is the minor reaction channel.

  19. Polyethylene oxide surfaces of variable chain density by chemisorption of PEO-thiol on gold: adsorption of proteins from plasma studied by radiolabelling and immunoblotting.

    PubMed

    Unsworth, Larry D; Sheardown, Heather; Brash, John L

    2005-10-01

    The mechanisms involved in the inhibition of protein adsorption by polyethylene oxide (PEO) are not completely understood, but it is believed that PEO chain length, chain density and chain conformation all play a role. In this work, surfaces formed by chemisorption of PEO-thiol to gold were investigated: the effects of PEO chain density, chain length (600, 750, 2000 and 5000 MW) and end-group (-OH, -OCH3) on protein adsorption from plasma are reported. Similar to previous single protein adsorption studies (L.D. Unsworth et al., Langmuir 2005;21:1036-41) it was found that, of the different surfaces investigated, PEO layers formed from solutions near the cloud point adsorbed the lowest amount of fibrinogen from plasma. Layers of hydroxyl-terminated PEO of MW 600 formed under these low solubility conditions showed almost complete suppression (versus controls) of the Vroman effect, with 20+/-1 ng/cm2 adsorbed fibrinogen at the Vroman peak and 6.7+/-0.6 ng/cm2 at higher plasma concentration. By comparison, Vroman peak adsorption was 70+/-20 and 50+/-3 ng/cm2, respectively, for 750-OCH3 and 2000-OCH3 layers formed under low solubility conditions; adsorption on these surfaces at higher plasma concentration was 16+/-9 and 12+/-3 ng/cm2. Thus in addition to the effect of solution conditions noted previously, the results of this study also suggest a chain end group effect which inhibits fibrinogen adsorption to, and/or facilitates displacement from, hydroxyl terminated PEO layers. Fibrinogen adsorption from plasma was not significantly different for surfaces prepared with PEO of molecular weight 750 and 2000 when the chain density was the same ( approximately 0.5 chains/nm2) supporting the conclusion that chain density may be the key property for suppression of protein adsorption. The proteins eluted from the surfaces after contact with plasma were investigated by SDS-PAGE and immunoblotting. A number of proteins were detected on the various surfaces including fibrinogen

  20. Thermal Decomposition Mechanisms of Lignin Model Compounds: From Phenol to Vanillin

    NASA Astrophysics Data System (ADS)

    Scheer, Adam Michael

    Lignin is a complex, aromatic polymer abundant in cellulosic biomass (trees, switchgrass etc.). Thermochemical breakdown of lignin for liquid fuel production results in undesirable polycyclic aromatic hydrocarbons that lead to tar and soot byproducts. The fundamental chemistry governing these processes is not well understood. We have studied the unimolecular thermal decomposition mechanisms of aromatic lignin model compounds using a miniature SiC tubular reactor. Products are detected and characterized using time-of-flight mass spectrometry with both single photon (118.2 nm; 10.487 eV) and 1 + 1 resonance-enhanced multiphoton ionization (REMPI) as well as matrix isolation infrared spectroscopy. Gas exiting the heated reactor (300 K--1600 K) is subject to a free expansion after a residence time of approximately 100 micros. The expansion into vacuum rapidly cools the gas mixture and allows the detection of radicals and other highly reactive intermediates. By understanding the unimolecular fragmentation patterns of phenol (C6H5OH), anisole (C6H 5OCH3) and benzaldehyde (C6H5CHO), the more complicated thermocracking processes of the catechols (HO-C 6H4-OH), methoxyphenols (HO-C6H4-OCH 3) and hydroxybenzaldehydes (HO-C6H4-CHO) can be interpreted. These studies have resulted in a predictive model that allows the interpretation of vanillin, a complex phenolic ether containing methoxy, hydroxy and aldehyde functional groups. This model will serve as a guide for the pyrolyses of larger systems including lignin monomers such as coniferyl alcohol. The pyrolysis mechanisms of the dimethoxybenzenes (H3C-C 6H4-OCH3) and syringol, a hydroxydimethoxybenzene have also been studied. These results will aid in the understanding of the thermal fragmentation of sinapyl alcohol, the most complex lignin monomer. In addition to the model compound work, pyrolyisis of biomass has been studied via the pulsed laser ablation of poplar wood. With the REMPI scheme, aromatic lignin decomposition

  1. Searching for trans ethyl methyl ether in Orion KL⋆

    NASA Astrophysics Data System (ADS)

    Tercero, B.; Cernicharo, J.; López, A.; Brouillet, N.; Kolesniková, L.; Motiyenko, R. A.; Margulès, L.; Alonso, J. L.; Guillemin, J.-C.

    2015-10-01

    We report on the tentative detection of trans ethyl methyl ether (tEME), t-CH3CH2OCH3, through the identification of a large number of rotational lines from each one of the spin states of the molecule towards Orion KL. We also search for gauche-trans-n-propanol, Gt-n-CH3CH2CH2OH, an isomer of tEME in the same source. We have identified lines of both species in the IRAM 30 m line survey and in the ALMA Science Verification data. We have obtained ALMA maps to establish the spatial distribution of these species. Whereas tEME mainly arises from the compact ridge component of Orion, Gt-n-propanol appears at the emission peak of ethanol (south hot core). The derived column densities of these species at the location of their emission peaks are ≤(4.0 ± 0.8) × 1015 cm-2 and ≤(1.0 ± 0.2) × 1015 cm-2 for tEME and Gt-n-propanol, respectively. The rotational temperature is ~100 K for both molecules. We also provide maps of CH3OCOH, CH3CH2OCOH, CH3OCH3, CH3OH, and CH3CH2OH to compare the distribution of these organic saturated O-bearing species containing methyl and ethyl groups in this region. Abundance ratios of related species and upper limits to the abundances of non-detected ethers are provided. We derive an abundance ratio N(CH3OCH3)/N(tEME) ≥ 150 in the compact ridge of Orion. This paper makes use of the following ALMA data: ADS/JAO.ALMA#2011.0.00009.SV. ALMA is a partnership of ESO (representing its member states), NSF (USA), and NINS (Japan) with NRC (Canada), NSC, and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO, and NAOJ. This work was also based on observations carried out with the IRAM 30-m telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain).Appendix A is available in electronic form at http://www.aanda.org

  2. A theoretical study on the hydrogen-bonding interactions between flavonoids and ethanol/water.

    PubMed

    Zheng, Yan-Zhen; Zhou, Yu; Liang, Qin; Chen, Da-Fu; Guo, Rui

    2016-04-01

    Ethanol and water are the solvents most commonly used to extract flavonoids from propolis. Do hydrogen-bonding interactions exist between flavonoids and ethanol/water? In this work, this question was addressed by using density functional theory (DFT) to provide information on the hydrogen-bonding interactions between flavonoids and ethanol/water. Chrysin and Galangin were chosen as the representative flavonoids. The investigated complexes included chrysin-H2O, chrysin-CH3CH2OH, galangin-H2O and galangin-CH3CH2OH dyads. Molecular geometries, hydrogen-bond binding energies, charges of monomers and dyads, and topological analysis were studied at the B3LYP/M062X level of theory with the 6-31++G(d,p) basis set. The main conclusions were: (1) nine and ten optimized hydrogen-bond geometries were obtained for chrysin-H2O/CH3CH2OH and galangin-H2O/CH3CH2OH complexes, respectively. (2) The hydrogen atoms except aromatic H1 and H5 and all of the oxygen atoms can form hydrogen-bonds with H2O and CH3CH2OH. Ethanol and water form strong hydrogen-bonds with the hydroxyl, carbonyl and ether groups in chrysin/galangin and form weak hydrogen-bonds with aromatic hydrogen atoms. Except in structures labeled A and B, chrysin and galangin interact more strongly with H2O than CH3CH2OH. (3) When chrysin and galangin form hydrogen-bonds with H2O and CH3CH2OH, charge transfers from the hydrogen-bond acceptor (H2O and CH3CH2OH in structures A, B, G, H, I, J) to the hydrogen-bond donor (chrysin and galangin in structure A, B, G, H, I, J). The stronger hydrogen-bond makes the hydrogen-bond donor lose more charge (A> B> G> H> I> J). (4) Most of the hydrogen-bonds in chrysin/galangin-H2O/CH3CH2OH complexes may be considered as electrostatic dominant, while C-O2···H in structures labeled E and C-O5···H in structures labeled J are hydrogen-bonds combined of electrostatic and covalent characters. H9, H7, and O4 are the preferred hydrogen-bonding sites.

  3. Reaction mechanism of ethylene glycol decomposition on Pt model catalysts: A density functional theory study

    NASA Astrophysics Data System (ADS)

    Lv, Cun-Qin; Yang, Bo; Pang, Xian-Yong; Wang, Gui-Chang

    2016-12-01

    Understanding and controlling bond beak sequence is important in catalytic processes. The DFT-GGA method combined with slab model was performed to study the ethylene glycol decomposition on various Pt model catalysts such as close-packed Pt(111), stepped Pt(211) and a more open one, Pt(100). Calculation results show that the adsorption energies of ethylene glycol and other decomposition species depend on the coordination number of surface atom, that is, low coordination number correspond to high adsorption energy. Moreover, it was found that final products of ethylene glycol decomposition are CO and H2 on all model catalysts, but the reaction mechanism varies: On Pt(111), the first step is Osbnd H bond scission, followed by Csbnd H bond cleavage, namely C2H6O2 → HOCH2CH2O + H → HOCH2CHO + 2H→ HOCH2CO +3H → OCH2CO + 4H → OCHCO + 5H → CO + HCO + 5H → 2CO + 6H→ 2CO + 3H2; On Pt(211) and Pt(100), however, it is a second Osbnd H bond cleavage that follows the initial Osbnd H bond scission, that is, C2H6O2 → HOCH2CH2O + H → OCH2CH2O + 2H → OCHCH2O + 3H → OCHCHO + 4H → 2HCO + 4H → 2CO + 6H → 2CO + 3H2 on Pt(211), and C2H6O2 →HOCH2CH2O+ H → OCH2CH2O + 2H→OCHCH2O+3H→OCCH2O+4H→CO+H2CO+4H→CO+HCO+5H→2CO+6H→2CO+3H2 on Pt(100) For the catalytic order of ethylene glycol to form H2, it may be determined based on the rate-controlling step, and it is Pt(111) > Pt(211) > Pt(100).

  4. Homogeneous solvation controlled photoreduction of cobalt(III) complexes in aqueous 2-methyl-2-propanol solutions. Linear solvation energy relationship and cyclic voltammetric analyses

    NASA Astrophysics Data System (ADS)

    Anbalagan, K.; Lydia, I. Sharmila

    2008-03-01

    The effect of solvent participation on the ligand-to-metal charge transfer (LMCT, L → Co III) reduction of the of Co III(en) 2Br(RC 6H 4NH 2) 2+ where R = m-OCH 3, p-F, H, m-CH 3, p-CH 3,p-OC 2H 5 and p-OCH 3 were examined in aqueous 2-methyl-2-propanol (Bu tOH) solutions. The change in the reduction behavior of Co III centre was also examined through cyclic voltammetric studies. The observed reduction in quantum yield due to LMCT excitation can mainly be accounted using linear solvation energy relationship (LSER) comprising model correlation equations. These consist of empirical parameters such as Grunwald-Winstein's solvent ionizing power, Y, Dimroth-Richardt's solvent micro-polarity parameter, ETN, Gutmann's donor number, DN N, along with Kamlet-Taft's solvatochromic parameters (hydrogen bond acceptor acidity/basicity α/ β and solvent dipolarity/polarizability, π*). The origin of solvent effect is found to be due to microscopic interaction between the solvent donor and the nitrogen-bound hydrogen of the ligand. Cyclic voltammograms show an irreversible reduction of Co III in DMF using Glassy Carbon Electrode, GCE, the redox peaks for the aniline complexes appear at -0.20 and 0.525 V. Irradiation of the complexes with UV light ( λ = 254 nm) in binary mixtures produce Co IIaq and the concentration of this species are highly dependent on xalc ( xalc = mole fraction of alcohol). The observed quantum yield (log ΦCo(II)) is found to be linearly related to mole fraction of organic co-solvent added in the mixture, therefore, log ΦCo(II) = 26.41 × 10 -2 when x2 = 0.0094 and 43.75 × 10 -2 when x2 = 0.076 for a typical complex Co III(en) 2Br( p-OCH 3C 6H 4NH 2) 2+ in aqueous 2-methyl-2-propanol at 300 K. Cyclic voltammetry and LSER analyses illustrate the variation of reduction property of Co(III) by the aryl ligand and homogeneous solvation of the excited state of the complex Co III(en) 2Br(RC 6H 4NH 2) 2+ in H 2O/Bu tOH mixtures.

  5. Crystal structure of μ6-chlorido-nona­kis­(μ-4-chloro­pyrazolato)bis-μ3-methoxo-hexa­copper(II)

    PubMed Central

    Shi, Kaige; Mathivathanan, Logesh; Raptis, Raphael G.

    2017-01-01

    The hexa­nuclear title compound, [{Cu3(μ3-OCH3)(μ-C3H2ClN2)3}2(μ-C3H2ClN2)3(μ6-Cl)] or [Cu6(C3H2ClN2)9(CH3O)2Cl], crystallizes in the space group Pbcn, with individual mol­ecules being located on a twofold rotation axis. The mol­ecule adopts a trigonal prismatic shape, with two trinuclear units linked by three 4-chloro­pyrazolate ligand bridges by encapsulating a Cl− anion in a μ6-coordination mode. In the crystal, individual mol­ecules are stacked into rods parallel to [1-10] that are arranged in a pseudo-hexa­gonal packing. Cohesion between mol­ecules is accomplished through weak C—H⋯Cl inter­actions. PMID:28217356

  6. The influence of oxygen on the surface chemistry of 1,2-propanediol on Pd(111)

    NASA Astrophysics Data System (ADS)

    Williams, Rhea M.; Medlin, J. Will

    2014-01-01

    The surface chemistry of 1,2-propanediol (PDO) has been studied on oxygen precovered Pd(111) using temperature programmed desorption (TPD) and high-resolution electron energy loss spectroscopy (HREELS). Adsorbed 1,2-propanedioxy (-OCH(CH3)CH2O-) forms from the activation of the O-H bonds. When the concentration of O(a) is large compared to 1,2-propanedioxy, no H2 is produced and the dialkoxide reacts to form H2O, CO through decarbonylation, and CO2 through decarboxylation. Unreacted oxygen also desorbs as O2 at high temperature. Conversely, when the concentration of O(a) is small relative to 1,2-propanedioxy, the dialkoxide reacts to form decomposition products (H2, CO), oxidation products (H2O, glyoxal, methylglyoxal, formaldehyde) and deoxygenation products (ethylene, propylene). Co-adsorbed oxygen increases the overall coverage of PDO that can undergo decomposition, which in turn strongly influences decomposition activation barriers and products.

  7. Laboratory simulation of the photoprocessing and warm-up of cometary and pre-cometary ices: Production of complex organic molecules

    NASA Technical Reports Server (NTRS)

    Schutte, W. A.; Allamandola, L. J.; Sanford, S. A.

    1991-01-01

    The recent missions to Comet Halley detected large quantities of organic material on grains as well as organic molecules in the gas phase. A possible origin of these materials is the energetic processing of ice mantles on the grains prior to comet formation, either in the pre-solar nebula or the interstellar medium. This process was simulated in the laboratory by depositing interstellar ice analogs (H2O/CH3OH/CO/NH3) on a cold (10 K) substrate with simultaneous UV irradiation. The material evaporating during warm-up of the photolyzed ice as well as the residue remaining at room temperature was analyzed by a number of techniques. It was found that a large number of organic molecules of various complexity are synthesized during the simulation process, stressing the possible significance of UV photolysis for producing the organic Comet material.

  8. Laboratory simulation of the photoprocessing and warm-up of cometary and pre-cometary ices - Production and analysis of complex organic molecules

    NASA Technical Reports Server (NTRS)

    Schutte, W. A.; Allamandola, L. J.; Sandford, S. A.

    1992-01-01

    The recent missions to Comet Halley detected large quantities of organic material on grains as well as organic molecules in the gas phase. A possible origin of these materials is the energetic processing of ice mantles on the grains prior to comet formation, either in the pre-solar nebula or the interstellar medium. This process was simulated in the laboratory by depositing interstellar ice analogs (H2O/CH3OH/CO/NH3) on a cold (10 K) substrate with simultaneous UV irradiation. The material evaporating during warm-up of the photolyzed ice as well as the residue remaining at room temperature was analyzed by a number of techniques. It was found that a large number of organic molecules of various complexity are synthesized during the simulation process, stressing the possible significance of UV photolysis for producing the organic Comet material.

  9. Electromagnetic radiation absorbers and modulators comprising polyaniline

    DOEpatents

    Epstein, Arthur J.; Ginder, John M.; Roe, Mitchell G.; Hajiseyedjavadi, Hamid

    1992-01-01

    A composition for absorbing electromagnetic radiation, wherein said electromagnetic radiation possesses a wavelength generally in the range of from about 1000 Angstroms to about 50 meters, wherein said composition comprises a polyaniline composition of the formula ##STR1## where y can be equal to or greater than zero, and R.sup.1 and R.sup.2 are independently selected from the group containing of H, --OCH.sub.3, --CH.sub.3, --F, --Cl, --Br, --I, NR.sup.3 .sub.2, --NHCOR.sup.3, --OH, --O.sup.-, SR.sup.3, --OCOR.sup.3, --NO.sub.2, --COOH, --COOR.sup.3, --COR.sup.3, --CHO, and --CN, where R.sup.3 is a C.sub.1 to C.sub.8 alkyl, aryl or aralkyl group.

  10. Cytotoxic polyphenols from the fungus Penicillium expansum 091 006 endogenous with the mangrove plant Excoecaria agallocha.

    PubMed

    Wang, Junfeng; Lu, Zhenyu; Liu, Peipei; Wang, Yi; Li, Jing; Hong, Kui; Zhu, Weiming

    2012-11-01

    As part of our ongoing chemical investigation of biologically active metabolites from marine-derived fungi, four new polyphenols containing both phenolic bisabolane and diphenyl ether units, expansols C-F (1-4), and one new diphenyl ether derivative, 3-O-methyldiorcinol (5), as well as twelve known compounds (6-17), were isolated from Penicillium expansum 091006 endogenous with the mangrove plant Excoecaria agallocha (Euphorbiaceae). The structures of the new metabolites were determined on the basis of NMR and mass spectroscopy. Among them, expansols C (1) and E (3) exhibited weak cytotoxicity against the HL-60 cell lines with IC50 values of 18.2 and 20.8 µM, respectively. The results showed that diphenyl ether substituted phenolic bisabolanes with a Δ7 double bond in the side chain are slightly less cytotoxic to HL-60 cell lines than the 7-OH or 7-OCH3 derivatives.

  11. In situ formation of cobalt oxide nanocubanes as efficient oxygen evolution catalysts.

    PubMed

    Hutchings, Gregory S; Zhang, Yan; Li, Jian; Yonemoto, Bryan T; Zhou, Xinggui; Zhu, Kake; Jiao, Feng

    2015-04-01

    Oxygen evolution from water poses a significant challenge in solar fuel production because it requires an efficient catalyst to bridge the one-electron photon capture process with the four-electron oxygen evolution reaction (OER). Here, a new strategy was developed to synthesize nonsupported ultrasmall cobalt oxide nanocubanes through an in situ phase transformation mechanism using a layered Co(OH)(OCH3) precursor. Under sonication, the precursor was exfoliated and transformed into cobalt oxide nanocubanes in the presence of NaHCO3-Na2SiF6 buffer solution. The resulting cobalt catalyst with an average particle size less than 2 nm exhibited a turnover frequency of 0.023 per second per cobalt in photocatalytic water oxidation. X-ray absorption results suggested a unique nanocubane structure, where 13 cobalt atoms fully coordinated with oxygen in an octahedral arrangement to form 8 Co4O4 cubanes, which may be responsible for the exceptionally high OER activity.

  12. Comparative study on pyrolysis of lignocellulosic and algal biomass using a thermogravimetric and a fixed-bed reactor.

    PubMed

    Yuan, Ting; Tahmasebi, Arash; Yu, Jianglong

    2015-01-01

    Pyrolysis characteristics of four algal and lignocellulosic biomass samples were studied by using a thermogravimetric analyzer (TGA) and a fixed-bed reactor. The effects of pyrolysis temperature and biomass type on the yield and composition of pyrolysis products were investigated. The average activation energy for pyrolysis of biomass samples by FWO and KAS methods in this study were in the range of 211.09-291.19kJ/mol. CO2 was the main gas component in the early stage of pyrolysis, whereas H2 and CH4 concentrations increased with increasing pyrolysis temperature. Bio-oil from Chlorellavulgaris showed higher content of nitrogen containing compounds compared to lignocellulosic biomass. The concentration of aromatic organic compounds such as phenol and its derivatives were increased with increasing pyrolysis temperature up to 700°C. FTIR analysis results showed that with increasing pyrolysis temperature, the concentration of OH, CH, CO, OCH3, and CO functional groups in char decreased sharply.

  13. Metabolic profiling of nuciferine in rat urine, plasma, bile and feces after oral administration using ultra-high performance liquid chromatography-diode array detection-quadrupole time-of-flight mass spectrometry.

    PubMed

    Wu, Xiao-Lei; Wu, Ming-Jiang; Chen, Xin-Ze; Ma, Hao-Ling; Ding, Li-Qin; Qiu, Feng; Pan, Qin; Zhang, De-Qin

    2017-03-18

    Nuciferine, a major alkaloid found in Nelumbinis Folium, exhibits a broad spectrum of bioactivities, such as antiobesity, anti-diabetes and anti-inflammatory. However, many research regarding nuciferine focused on the extraction, isolation and biological activity, the metabolism is not comprehensively explained in vivo. Thence, the present of this paper is to establish a simple method for speculating metabolites of nuciferine. A total of 15 metabolites were detected and tentatively identified through ultra high performance liquid chromatography-diode array detection-quadrupole time-of-flight mass spectrometry (UHPLC-DAD-QTOF-MS), including 7 new metabolites. Among them, we also discovered a previously unmentioned metabolically active site at the C1-OCH3 position. These metabolites suggested that demethylation, oxidation, glucuronidation and sulfation were major metabolic pathways. This study provided significant experiment basis for its safety estimate and valuable information about the metabolism of nuciferine, which will be advantageous for new drug development.

  14. Luminescence from Vacuum-Ultraviolet-Irradiated Cosmic Ice Analogs and Residues

    NASA Technical Reports Server (NTRS)

    Gudipati, Murthy S.; Dworkin, Jason P.; Chillier, Xavier D. F.; Allamandola, Louis J.

    2003-01-01

    Here we report a study of the optical luminescent properties for a variety of vacuum-ultraviolet (VUV)- irradiated cosmic ice analogs and the complex organic residues produced. Detailed results are presented for the irradiated, mixed molecular ice: H2O:CH3OH:NH3:CO (100:50:1:1), a realistic representation for an interstellar/precometary ice that reproduces all the salient infrared spectral features associated with interstellar ices. The irradiated ices and the room-temperature residues resulting from this energetic processing have remarkable photoluminescent properties in the visible (520-570 nm). The luminescence dependence on temperature, thermal cycling, and VUV exposure is described. It is suggested that this type of luminescent behavior might be applicable to solar system and interstellar observations and processes for various astronomical objects with an ice heritage. Some examples include grain temperature determination and vaporization rates, nebula radiation balance, albedo values, color analysis, and biomarker identification.

  15. Intramolecular structure and dynamics of mequinol and guaiacol in the gas phase: Rotationally resolved electronic spectra of their S{sub 1} states

    SciTech Connect

    Ruiz-Santoyo, José Arturo; Rodríguez-Matus, Marcela; Álvarez-Valtierra, Leonardo E-mail: gmerino@mda.cinvestav.mx; Cabellos, José Luis; Merino, Gabriel E-mail: gmerino@mda.cinvestav.mx; Yi, John T.; Pratt, David W.; Schmitt, Michael

    2015-09-07

    The molecular structures of guaiacol (2-methoxyphenol) and mequinol (4-methoxyphenol) have been studied using high resolution electronic spectroscopy in a molecular beam and contrasted with ab initio computations. Mequinol exhibits two low frequency bands that have been assigned to electronic origins of two possible conformers of the molecule, trans and cis. Guaiacol also shows low frequency bands, but in this case, the bands have been assigned to the electronic origin and vibrational modes of a single conformer of the isolated molecule. A detailed study of these bands indicates that guaiacol has a vibrationally averaged planar structure in the ground state, but it is distorted along both in-plane and out-of-plane coordinates in the first electronically excited state. An intramolecular hydrogen bond involving the adjacent   –OH and   –OCH{sub 3} groups plays a major role in these dynamics.

  16. Structural studies of methyl brevifolincarboxylate in solid state by means of NMR spectroscopy and DFT calculations

    NASA Astrophysics Data System (ADS)

    Wolniak, Michał; Tomczyk, Michał; Gudej, Jan; Wawer, Iwona

    2006-12-01

    Methyl brevifolincarboxylate isolated from the herb of Potentilla argentea L. (Rosaceae) is a representative of the naturally occurring polyphenols. The compound is of pharmaceutical interest mainly because of its antiviral and antioxidant properties. 13C NMR spectra were recorded for solution and solid phase. 13C CPMAS spectra were assigned by comparison with solution data, dipolar dephasing and short contact time experiments. The correctness of assignments was verified by GIAO DFT calculations of shielding constants. The differences between the solution and solid state chemical shift values were explained in terms of orientation of OH groups and intramolecular hydrogen bonds. The splitting of the C1 dbnd O resonance shows that there exists a polymorphism in the solid phase, which might be due to the formation of intramolecular hydrogen bond involving carbonyl or methoxy oxygen (i.e. C10 sbnd OH⋯O dbnd C or C10 sbnd OH⋯OCH 3).

  17. Phase Transitions, Hydrogen Bond and Crystal Dynamics of p-Methylbenzyl Alcohol as Studied by Single Crystal X-ray Diffraction and 2H NMR

    NASA Astrophysics Data System (ADS)

    Hashimoto, Masao; Harada, Michiko; Mizunoa, Motohiro; Hamada, Masanori; Ida, Tomonori; Suhara, Masahiko

    2002-07-01

    The title compound (pMBA) was found to undergo a first-order phase transition at 211 K (Tc1). Another transition with subtle enthalpy change appeared at 172 K (Tc2). Crystal structure determinations at various temperatures revealed that the transition at Tc1 was accompanied by remarkable changes in the molecular conformations around the CH2-C and O-CH2 bonds and a reversal of the direction of the O-H O hydrogen bond. Experiments of 2H NMR were carried out on pMBA-d where the hydroxyl hydrogen of pMBA was selectively deuterated. Analyses of the 2H NMR spectra and the temperature dependence of T1 of the 2H NMR indicated occurrence of jumping motions of 2H between asymmetric potential wells at temperatures lower than Tc1

  18. Heterobimetallic dinuclear lanthanide alkoxide complexes as acid-base difunctional catalysts for transesterification.

    PubMed

    Zeng, Ruijie; Sheng, Hongting; Zhang, Yongcang; Feng, Yan; Chen, Zhi; Wang, Junfeng; Chen, Man; Zhu, Manzhou; Guo, Qingxiang

    2014-10-03

    A practical lanthanide(III)-catalyzed transesterification of carboxylic esters, weakly reactive carbonates, and much less-reactive ethyl silicate with primary and secondary alcohols was developed. Heterobimetallic dinuclear lanthanide alkoxide complexes [Ln2Na8{(OCH2CH2NMe2)}12(OH)2] (Ln = Nd (I), Sm (II), and Yb (III)) were used as highly active catalysts for this reaction. The mild reaction conditions enabled the transesterification of various substrates to proceed in good to high yield. Efficient activation of transesterification may be endowed by the above complexes as cooperative acid-base difunctional catalysts, which is proposed to be responsible for the higher reactivity in comparison with simple acid/base catalysts.

  19. Lignin pyrolysis products, lignans, and resin acids as specific tracers of plant classes in emissions from biomass combustion

    SciTech Connect

    Simoneit, B.R.T. ); Rogge, W.F.; Cass, G.R. ); Mazurek, M.A. ); Standley, L.J. ); Hildemann, L.M. )

    1993-11-01

    Biomass smoke aerosols contain thermally unaltered and partially altered biomarker compounds from major vegetation taxa. These compounds range from C[sub 8] to C[sub 31] and include phytosterols, lignans, phenolic products from lignin, and diterpenoids from resins. Certain of the higher molecular weight biomarkers are vaporized from the parent plant material and subsequently condense unaltered into the particle phase. Other compounds undergo pyrolytic alteration and possibly dimerization. In both cases it is possible to assign many of these compounds to the plant taxa of the unburned fuel. The diterpenoids are good indicators for smoke from burning of gymnosperm wood. The relative distribution of the OH/OCH[sub 3] substituent patterns on the phenolic products indicates the plant class of the biomass that was burned. Application of these relationships to the interpretation of ambient smoke aerosols may permit further evaluation of the sources that contribute to regional biomass burning. 80 refs., 5 figs., 1 tab.

  20. Induced cholesteric systems based on some cyano derivatives as host phases

    NASA Astrophysics Data System (ADS)

    Shkolnikova, Natalya I.; Kutulya, Lidiya A.; Vashchenko, V. V.; Fedoryako, A. P.; Lapanik, V. I.; Posledovich, N. R.

    2002-12-01

    Macroscopical properties of some induced cholesteric compositions based on 4-pentyl-4'-cyano derivatives of biphenyl and phenylcyclohexane as host phases have been investigated. The series of N-arylidene derivatives of (S)-1-phenylethylamine with varied both rigid moiety of the N-arylidene fragment and terminal substituent was used as chiral dopants. The influence of the chiral dopant molecular structure as well as of physical properties of the host phases used on the helical twisting power, the temperature dependence of the induced helical pitch and the N* mesophase thermal stability has been characterized. It has been concluded that the distinctions in properties of the LC systems containing the OCH2 and COO linking groups are caused by their different conformational states.

  1. Methanol in dark clouds

    NASA Technical Reports Server (NTRS)

    Friberg, P.; Hjalmarson, A.; Madden, S. C.; Irvine, W. M.

    1988-01-01

    The first observation of methanol in cold dark clouds TMC 1, L 134 N, and B 335 is reported. In all three clouds, the relative abundance of methanol was found to be in the range of 10 to the -9th (i.e., almost an order of magnitude more abundant than acetaldehyde), with no observable variation between the clouds. Methanol emission showed a complex velocity structure; in TMC 1, clear indications of non-LTE were observed. Dimethyl ether was searched for in L 134 N; the upper limit of the column density of dimethyl ether in L 134 N was estimated to be 4 x 10 to the 12th/sq cm, assuming 5 K rotation temperature and LTE. This limit makes the abundance ratio (CH3)2O/CH3OH not higher than 1/5, indicating that dimethyl ether is not overabundant in this dark cloud.

  2. Crystal structure of μ6-chlorido-nona-kis-(μ-4-chloro-pyrazolato)bis-μ3-methoxo-hexa-copper(II).

    PubMed

    Shi, Kaige; Mathivathanan, Logesh; Raptis, Raphael G

    2017-02-01

    The hexa-nuclear title compound, [{Cu3(μ3-OCH3)(μ-C3H2ClN2)3}2(μ-C3H2ClN2)3(μ6-Cl)] or [Cu6(C3H2ClN2)9(CH3O)2Cl], crystallizes in the space group Pbcn, with individual mol-ecules being located on a twofold rotation axis. The mol-ecule adopts a trigonal prismatic shape, with two trinuclear units linked by three 4-chloro-pyrazolate ligand bridges by encapsulating a Cl(-) anion in a μ6-coordination mode. In the crystal, individual mol-ecules are stacked into rods parallel to [1-10] that are arranged in a pseudo-hexa-gonal packing. Cohesion between mol-ecules is accomplished through weak C-H⋯Cl inter-actions.

  3. A sodar study of the temperature structure parameter in the convective boundary layer

    NASA Astrophysics Data System (ADS)

    Dubosclard, G.

    1982-03-01

    From sodar measurements gathered during the Voves experiment (France, summer 1977), the variations of the temperature structure parameter C T 2 were studied in the morning planetary boundary layer. Dimensionless profiles of C T 2 are consistent with the mixed-layer scaling of Kaimal et al. (1976); however, for z < 0,5 z i, the decrease of C T 2 as z 4/3 should be weighted according to Frisch and Ochs (1975). When the final breakup of the nocturnal inversion is achieved, the variations of the maximum of the C T 2 profile are in good agreement with those predicted by Wyngaard and Le Mone (1980). Discrepancies are observed mainly when the mixed layer is shallow and mechanical turbulence is important compared with buoyancy-driven turbulence.

  4. Charge and energy flow in π+ p, K + p and pp interactions at 250 GeV/c

    NASA Astrophysics Data System (ADS)

    Ajinenko, I. V.; Baladyan, S. G.; Belokopytov, Yu. A.; Böttcher, H.; Botterweck, F.; Chliapnikov, P. V.; Crijns, F.; de Roeck, A.; de Wolf, E. A.; Dreher, C.; Dziunikowska, K.; Ermolov, P. F.; Garutchava, Z. C.; Gerdyukov, L. N.; Gevorkyan, G. V.; Grässler, H.; van Hal, P.; Haupt, T.; Kittel, W.; Meijers, F.; Michałowska, A. B.; Nikolaenko, V. I.; Oliveira, L. C.; Olkiewicz, K.; Pöllänen, R.; Ronjin, V. M.; Rybin, A. M.; Saarikko, H. M. T.; Schmitz, W.; Scholten, L.; Shabalina, E. K.; Stepaniak, J.; Tchikilev, O. G.; Tomaradze, A. G.; Uvarov, V. A.; Verbeure, F.; Wischnewski, R.; Yarba, Yu. V.; Zielinski, W.

    1989-03-01

    We present data on the flow of energy and charge in π+ p, K + p and pp interactions at 250 GeV/c. The energy and charge flow in the beam c.m. hemisphere is analysed in terms of the cluster-invariant Bialas-Ochs-Stodolsky variable λ=cot θ/ E jet. The profile functions dQ/dλ and dE/dλ indicate a widening in p T of jets between 32 and 250 GeV/c incident laboratory momentum, whereas the ratio dQ/dE is energy independent. The data are compared to μ p deep-inelastic scattering resutls and to expectations from the single string LUND model, the Dual Parton Model and the two-string LUND model (FRITIOF).

  5. Quantitative estimate of pion fluctuation and its multiplicity dependence in nuclear collisions

    NASA Astrophysics Data System (ADS)

    Ghosh, Dipak; Deb, Argha; Dutta, Srimonti

    2009-02-01

    This paper presents the results of an investigation on the multiplicity dependence of the fluctuation pattern of pions for the entire accelerator energy range from 2.1 to 200 AGeV. The data set for produced pions is divided into four sets depending on the number of shower tracks ns. Analysis is carried out in two-dimensional η-phi space with the Hurst exponent to take care of the anisotropy of the phase space. The Hurst exponent is extracted by fitting one-dimensional factorial moment saturation curves to Ochs' saturation formula. The values of the effective fluctuation strength α eff are estimated and multiplicity dependence is studied w.r.t. α eff and the Hurst exponent H. It is highly interesting to observe that both fluctuation strength and degree of anisotropy (characterized by H) depend on pion multiplicity. The multiplicity dependence is more pronounced at lower projectile energy. The results of the study are discussed in detail.

  6. Possible Effects of Collisional Breakup on Mixed-Phase Deep Convection Simulated by a Spectral (Bin) Cloud Model.

    NASA Astrophysics Data System (ADS)

    Seifert, Axel; Khain, Alexander; Blahak, Ulrich; Beheng, Klaus D.

    2005-06-01

    The effects of the collisional breakup of raindrops are investigated using the Hebrew University Cloud Model (HUCM). The parameterizations, which are combined in the new breakup scheme, are those of Low and List, Beard and Ochs, as well as Brown. A sensitivity study reveals strong effects of collisional breakup on the precipitation formation in mixed-phase deep convective clouds for strong as well as for weak precipitation events. Collisional breakup reduces the number of large raindrops, increases the number of small raindrops, and, as a consequence, decreases surface rain rates and considerably reduces the speed of rain formation. In addition, it was found that including breakup can lead to a more intense triggering of secondary convective cells. But a statistical comparison with observed raindrop size distributions shows that the parameterizations might systematically overestimate collisional breakup.

  7. Tungsten hydride complex as a template in organic inorganic hybrid materials

    NASA Astrophysics Data System (ADS)

    Montinho, Isilda; Boev, Victor; Fonseca, António M.; Silva, Carlos J. R.; Neves, Isabel C.

    2003-03-01

    A tungsten hydride complex, [WH 2( η2-OOCCH 3)(Ph 2PCH 2CH 2PPh 2) 2][BPh 4], was dispersed in a hybrid matrix synthesized by a sol-gel process. The host matrix of the so-called ureasil is a network of silica to which oligopolyoxyethylene chains [POE, (OCH 2CH 2) n] are grafted by means of urea cross-links. The free complex and sol-gel materials were characterized by thermal analysis (DSC) and spectroscopic methods (FT-IR and UV/Vis). The data gathered indicate that the tungsten(IV) complex is immobilized in the host matrix, and it exhibits structural properties different from those of the free form. These differences could arise either from distortions caused by steric effects imposed by the structure of hybrid matrix or by interactions with the matrix.

  8. A quasielastic neutron scattering study of the dynamics of alkane and ether molecules tethered to the surface of MCM-41

    SciTech Connect

    Kintzel, Edward J; Herwig, Kenneth W; Kidder, Michelle; Britt, Phillip F; Buchanan III, A C; Chaffe, Alan

    2007-01-01

    The motion of 1,3-diphenylpropane (DPP, Si-O-C6H4(CH2)3C6H5) and phenethyl phenyl ether (PPE, Si-O-C6H4(CH2)2OC6H5 and Si-O-C6H4O(CH2)2C6H5) tethered to the interior pore surface of MCM-41 silica was investigated using quasielastic neutron scattering. Quasielastic scans over an energy range of } 17 eV were carried out at temperatures in the range 240-320 K using the High Flux Backscattering Spectrometer at the NIST Center for High Resolution Neutron Scattering. Quasielastic data were fit with a single-lorentzian and a delta function, convoluted with the instrument resolution. These results elicit the role temperature has on the motion of these molecules tethered within the pores and the interactions of the molecules with the pore walls.

  9. Synthesis and stability of liquid molecular DT

    SciTech Connect

    Souers, P.C.; Fearon, E.M.; Garza, R.G.; Friffith, C.M.; Mayhugh, S.R.; Mapoles, E.R.; Tsugawa, R.T.; Sater, J.D.; Collins, G.W.; Gaines, J.R.

    1988-05-01

    Regular equimolar deuterium-tritium is a mixture of 25 mol% T/sub 2/-50% DT-25% D/sub 2/. We have synthesized molecular DT of greater purity by the reaction LiT + CH/sub 3/OD ..-->.. DT + LiOCH/sub 3/, run at 243/degree/K. With both the alcohol and reactor-to-cryostat transfer lines at room temperature, we obtain 88 mol% DT purity. By cooling the alcohol and holding the transfer lines at 80/degree/K, the yield rose to 95% DT. The DT disproportionated to D/sub 2/ and T/sub 2/ with a 1e time constant of about 100 h in the liquid at 20.5/degree/K. Nuclear magnetic resonance data showed that the eventual T/sub 2/-DT-D/sub 2/ equilibrium is probably a /open quotes/hot-atom/close quotes/ one. 15 refs., 4 figs., 1 tab.

  10. Synthesis and stability of liquid molecular DT

    SciTech Connect

    Souers, P.C.; Fearon, E.M.; Garza, R.G.; Griffith, C.M.; Mayhugh, S.R.; Mapoles, E.R.; Tsurgawa, R.T.; Sater, J.D.; Collins, G.W.; Gaines, J.R.

    1988-01-01

    Regular equimolar deuterium-tritium is a mixture of 25 mol% T/sub 2/-50% DT-25% D/sub 2/. We have synthesized molecular DT of greater purity by the reaction LiT + CH/sub 3/OD ..-->.. DT + LiOCH/sub 3/, run at 243/degree/K. With both the alcohol and reactor-to-cryostat transfer lines at room temperature, we obtain 88 mol% DT purity. By cooling the alcohol and holding the transfer lines at 80/degree/K, the yield rose to 95% DT. The DT disproportionated to D/sub 2/ and T/sub 2/ with a le-time constant of about 100 hours in the liquid at 20.5/degree/K. Nuclear magnetic resonance data showed that the eventual T/sub 2/-DT-D/sub 2/ equilibrium is probably a /open quotes/hot-atom/close quotes/ one.

  11. Schiff base mediated sol-gel polymerization

    SciTech Connect

    Lindquist, D.A.; Harrison, C.M.; Williams, B.; Morris, R.D.

    1996-12-31

    Formation of a Schiff base imine by reacting a primary amine with either an aldehyde or ketone was initiated by an aluminum compound acting as a Lewis acid catalyst. The water byproduct of the reaction then was used as an in situ reagent for subsequent hydrolysis and sol-gel condensation of the aluminum species. These reactions yielded a gel network containing the entrained Schiff base. Two examples of this synthetic approach are described with two different aluminum catalyst/reagents: a diethylaluminum diethylphosphate ester [(CH{sub 3}CH{sub 2}){sub 2}Al-O-P(O)(OCH{sub 2}CH{sub 3}){sub 2}] and triethyl aluminum [Al(CH{sub 3}CH{sub 2}){sub 3}]. Anhydrous ammonia and acetone were used as the Schiff base precursors.

  12. Structure-activity investigation on the gene transfection properties of cardiolipin mimicking gemini lipid analogues.

    PubMed

    Bajaj, Avinash; Paul, Bishwajit; Kondaiah, Paturu; Bhattacharya, Santanu

    2008-06-01

    A structure-activity relationship has been explored on the gene transfection efficiencies of cardiolipin mimicking gemini lipid analogues upon variation of length and hydrophilicity of the spacer between the cationic ammonium headgroups and lipid hydrocarbon chain lengths. All the gemini lipids were found to be highly superior in gene transfer abilities as compared to their monomeric lipid and a related commercially available formulation. Pseudoglyceryl gemini lipids bearing an oxyethylene (-CH2-(CH2-O-CH2)m-CH2-) spacer were found to be superior gene transfecting agents as compared to those bearing polymethylene (-CH2)m-) spacers. The major characteristic feature of the present set of gemini lipids is their serum compatibility, which is most often the major hurdle in liposome-mediated gene delivery.

  13. OH-radical induced degradation of hydroxybenzoic- and hydroxycinnamic acids and formation of aromatic products—A gamma radiolysis study

    NASA Astrophysics Data System (ADS)

    Krimmel, Birgit; Swoboda, Friederike; Solar, Sonja; Reznicek, Gottfried

    2010-12-01

    The OH-radical induced degradation of hydroxybenzoic acids (HBA), hydroxycinnamic acids (HCiA) and methoxylated derivatives, as well as of chlorogenic acid and rosmarinic acid was studied by gamma radiolysis in aerated aqueous solutions. Primary aromatic products resulting from an OH-radical attachment to the ring (hydroxylation), to the position occupied by the methoxyl group (replacement -OCH 3 by -OH) as well as to the propenoic acid side chain of the cinnamic acids (benzaldehyde formations) were analysed by HPLC-UV and LC-ESI-MS. A comparison of the extent of these processes is given for 3,4-dihydroxybenzoic acid, vanillic acid, isovanillic acid, syringic acid, cinnamic acid, 4-hydroxycinnamic acid, caffeic acid, ferulic acid, isoferulic acid, chlorogenic acid, and rosmarinic acid. For all cinnamic acids and derivatives benzaldehydes were significant oxidation products. With the release of caffeic acid from chlorogenic acid the cleavage of a phenolic glycoside could be demonstrated. Reaction mechanisms are discussed.

  14. Solid CO2 in laboratory and in dense molecular clouds

    NASA Astrophysics Data System (ADS)

    Palumbo, M. E.; Baratta, G. A..; Strazzulla, G.

    1999-03-01

    We have studied by laboratory infrared spectroscopy the profile of the band due to the CO2 bending mode in different H2O:CH3OH:CO2 mixtures. Icy mixtures have been accreted on a substrate at 12.5 K inclined of 45 degrees with respect to the infrared beam of the spectrometer. Spectra have been taken with the electric vector of the infrared beam parallel (P polarized) and perpendicular (S polarized) to the plane of incidence. The samples have been warmed up and spectra have been taken at different temperatures. We have found that the profile of the band due to the CO2 bending mode strongly depends on the temperature. Furthermore for the mixtures studied, the profile of this band is different in the two different polarization cases. In particular features not due to absorption appear in the P polarization case. Here we discuss the implications of these results in the astrophysical context.

  15. Crystal structure and C—H⋯F hydrogen bonding in the fluorinated bis-benzoxazine: 3,3′-(ethane-1,2-di­yl)bis­(6-fluoro-3,4-di­hydro-2H-1,3-benzoxazine)

    PubMed Central

    Rivera, Augusto; Rojas, Jicli José; Ríos-Motta, Jaime; Bolte, Michael

    2016-01-01

    The title fluorinated bis­benzoxazine, C18H18F2N2O2, crystallizes with one half-mol­ecule in the asymmetric unit, which is completed by inversion symmetry. The fused oxazine ring adopts an approximately half-chair conformation. The two benzoxazine rings are oriented anti to one another around the central C—C bond. The dominant inter­molecular inter­action in the crystal structure is a C—H⋯F hydrogen bond between the F atoms and the axial H atoms of the OCH2N methyl­ene group in the oxazine rings of neighbouring mol­ecules. C—H⋯π contacts further stabilize the crystal packing. PMID:27746952

  16. Luminescence from VUV Irradiated Cosmic Ice Analogs and Organic Residues

    NASA Technical Reports Server (NTRS)

    Gudipati, Murthy S.; Dworkin, Jason P.; Chillier, Xavier; Allamandola, Louis J.; DeVincenzi, Donald (Technical Monitor)

    2002-01-01

    The optical luminescent properties for a variety of vacuum-ultraviolet (VUV) irradiated cosmic ice analogs and the complex organic residues produced from irradiation might be applicable to Solar System and interstellar observations and processes for various astronomical objects with an ice heritage. Some examples include grain temperature determination and vaporization rates, nebula radiation balance, albedo values, color analysis, and biomarker identification. Detailed results are presented for the mixed molecular ice: H2O:CH3OH:NH3:CO (100:50:1:1), a realistic representation for an interstellar/precometary ice. The irradiated ices and the room-temperature residues resulting from this energetic processing have remarkable photoluminescent properties in the visible (520-570 nm). The luminescence dependence on temperature, thermal cycling, and VUV exposure of the residue is described.

  17. Hydrolysis of microporous polyamide-6 membranes as substrate for in situ synthesis of oligonucleotides

    NASA Astrophysics Data System (ADS)

    Tang, Jianxin; He, Nongyue; Nie, Libo; Xiao, Pengfeng; Chen, Hong

    2004-02-01

    This article provides a novel method of preparing substrate for in situ synthesis of oligonucleotide by hydrolyzing microporous polyamide-6 membranes in a 0.01 mol/l/NaOH/(H 2O-CH 3OH) mixture medium with refluxing about 36 h. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) demonstrated the emergence of amines (NH 2) on the surface. Optimum hydrolyzing conditions were determined through the ultra-violet (UV) spectra. A pH value of 12 and a hydrolysis time of 36 h are the preferred conditions for the modification. The treated membrane can be applied to in situ synthesis of oligonucleotide and, for example, the oligonucleotide probes of 5 '-AAC CAC CAA ACA CAC-3 ' were successfully synthesized on the hydrolyzed membrane. The single step coupling efficiency determined by ultraviolet (UV) spectra is above 98%.

  18. A search for parent molecules at millimetre wavelengths in Comets Austin 1990 V and Levy 1990 XX - Upper limits for undetected species

    NASA Astrophysics Data System (ADS)

    Crovisier, J.; Bockelee-Morvan, D.; Colom, P.; Despois, D.; Paubert, G.

    1993-03-01

    The microwave spectra of Comets Austin 1990 V and Levy 1990 XX were observed with the IRAM 30-m radio telescope. As we have reported previously, the HCN, H2S, H2CO, and CH3OH molecules were detected. In addition, the lines of several other molecules of cometary interest were searched for without success, either during dedicated searches or serendipitously: H2O2, CH3CCH, HCOOH, C2H5OH, CH3OCH3, CH3COOH, HC3HO, HC3N, and many others. We report these searches in detail and evaluate the corresponding limits on the production rates. For several molecules, this limit is of the order of 0.001 relative to water, or less. The consequences for the nature of comets are discussed.

  19. Fine-Tuning of Saponification-Triggered Gelation by Strategic Modification of Peripheral Substituents: Gelation Regulators.

    PubMed

    Kumar, Ashish; Singh, Roop Shikha; Kumar, Amit; Ali, Afsar; Biswas, Arnab; Pandey, Daya Shankar

    2016-09-19

    A pioneering approach towards controlling the efficiency of saponification assisted gelation in ethyl ester based Zn(II) -complexes have been described. Using four new ester containing bis-salen Zn(II) complexes (C1-C4) involving different para-azo phenyl substituted ligands it has been clearly shown that gelation efficiency is greatly influenced by the electronic effects of the substituents (-H (C1), -CH3 (C2), -NO2 (C3), and -OCH3 (C4)). Morphological, photophysical, and rheological investigations corroborated the experimental observations well and established that gelation efficiency was enhanced with electron-withdrawing characteristics of substituents (C4

  20. Comparative Study of Ether-Based Electrolytes for Application in Lithium-Sulfur Battery.

    PubMed

    Carbone, Lorenzo; Gobet, Mallory; Peng, Jing; Devany, Matthew; Scrosati, Bruno; Greenbaum, Steve; Hassoun, Jusef

    2015-07-01

    Herein, we report the characteristics of electrolytes using various ether-solvents with molecular composition CH3O[CH2CH2O]nCH3, differing by chain length, and LiCF3SO3 as the lithium salt. The electrolytes, considered as suitable media for lithium-sulfur batteries, are characterized in terms of thermal properties (TGA, DSC), lithium ion conductivity, lithium interface stability, cyclic voltammetry, self-diffusion properties of the various components, and lithium transference number measured by NMR. Furthermore, the electrolytes are characterized in lithium cells using a sulfur-carbon composite cathode by galvanostatic charge-discharge tests. The results clearly evidence the influence of the solvent chain length on the species mobility within the electrolytes that directly affects the behavior in lithium sulfur cell. The results may effectively contribute to the progress of an efficient, high-energy lithium-sulfur battery.

  1. Computational Study of Monosubstituted Azo(tetrazolepentazolium)-Based Ionic Dimers.

    PubMed

    Pimienta, Ian S O

    2015-06-04

    The structures of monosubstituted azo(tetrazolepentazolium) cations (N11CHR(+)), oxygen-rich anions such as N(NO2)2(-), NO3(-), and ClO4(-), and the corresponding ion pairs are investigated using ab initio quantum chemistry calculations. The substituents (R) used are H, F, CH3, CN, NH2, OH, OCH3, N3, NF2, and C2H3. The stability of the protonated cation is explored by examining the decomposition pathway of the protonated cation (N11CH2(+)) to yield molecular N2 fragments. The heats of formation of these cations, which are based on isodesmic (bond type conserving) reactions, are dependent on the nature of the substituents. Ionic dimer structures are obtained, but side reactions including proton transfer, binding, and hydrogen bonding are observed in the gas phase. Implicit solvation studies are performed to determine the solution properties of the ion pairs.

  2. Organic solids produced from simple C/H/O/N ices by charged particles - Applications to the outer solar system

    SciTech Connect

    Khare, B.N.; Thompson, W.R.; Chyba, C.F.; Sagan, C.; Arakawa, E.T.

    1989-01-01

    The effects of charged particle irradiation by cold plasma discharge on surfaces of H2O:CH4 clathrate with a 200:1 ratio and on ices composed of H2O and C2H6 or C2H2 are examined. The molecules studies are found in Comet Halley and are plausible constituents in icy outer solar system objects. The IR transmission spectra of four ice-tholin residues obtained in the laboratory are compared with spectra produced by irradiation of gases and ices containing simple hydrocarbons. The similarities between CH4 clathrate residue and Halley organic grains, and the surface transport or atmospheric replenishment activity on Triton and Pluto are discussed. 56 refs.

  3. Mechanistic implications of the active species involved in the oxidation of hydrocarbons by iron complexes of pyrazine-2-carboxylic acid.

    PubMed

    Tanase, Stefania; Marques-Gallego, Patricia; Browne, Wesley R; Hage, Ronald; Bouwman, Elisabeth; Feringa, Ben L; Reedijk, Jan

    2008-04-21

    The reactivity towards H(2)O(2) of the complexes [Fe(pca)(2)(py)(2)].py (1) and Na(2){[Fe(pca(3))](2)O}.2H(2)O.CH(3)CN (2) (where pca(-) is pyrazine-2-carboxylate) and their catalytic activity in the oxidation of hydrocarbons is reported. Addition of H(2)O(2) to 1 results in the formation of a dinuclear Fe(III)-(mu-O)-Fe(III) species characterized spectroscopically and by cyclic voltammetry. By contrast, treatment of 2 with H(2)O(2) results in the formation of mononuclear iron(II) complexes, [Fe(pca)(2)(solvent)(2)]. The experimental results indicate that the catalytic activity of the starting complexes 1 and 2 is strongly dependent on the species formed in solution.

  4. Synthesis and electrochemical properties of bipyrimidine bridged triruthenium complexes.

    PubMed

    Ohtsu, Hiroyoshi; Kitazume, Jun; Yamaguchi, Tadashi

    2011-08-07

    A new μ(4)-bpym-bridged dimer of an oxoacetao-triruthenium complex with carbonyl, [{Ru(3)O(CH(3)COO)(5)(CO)(py)}(2)(μ(4)-bpym)], was synthesized. The complex possesses two stable mixed-valence states associated with Ru(3)(III,III,II)/Ru(3)(III,II,II) and Ru(3)(III,III,III)/Ru(3)(III,III,II). The IR-spectroelectrochemistry reveals ν(CO) spectra in five oxidation states, Ru(3)(III,III,III)-Ru(3)(III,III,III) to Ru(3)(III,II,II)-Ru(3)(III,II,II) and both the mixed-valence states show a spectrum indicating medium interaction between the Ru(3) units.

  5. Living polymerization of (o-(trimethylsilyl)phenyl)acetylene using `small alkoxide` molybdenum(VI) initiators

    SciTech Connect

    Schrock, R.R.; Luo, S.; Zanetti, N.C.; Fox, H.H.

    1994-09-01

    (o-(Trimethylsily)phenyl)acetylene (o-TM-SPA) is polymerized in a living manner by the new `small alkoxide` initiators Mo(CHCMe{sub 2}Ph)(N-1-adamantyl) [OCH(CF{sub 3}){sub 2}]{sub 2}(2,4-lutidine) (1b) and Mo(CHCMe{sub 2}-Ph)(NAr{prime})(OC{sub 6}F{sub 5}){sub 2}(quinulidine) (2; Ar{prime} = 2,6-C{sub 6}H{sub 3}Me{sub 2}) to give low-polydispersity polyenes containing up to 100 equiv of o-TMSPA. The thermodynamically most stable form of poly(o-TMSPA) that contains <25 double bonds is air-sensitive and has a significantly red-shifted {lambda}{sub max}. 29 refs., 1 fig., 1 tab.

  6. Consider the DME alternative for diesel engines

    SciTech Connect

    Fleisch, T.H.; Meurer, P.C.

    1996-07-01

    Engine tests demonstrate that dimethyl ether (DME, CH{sub 3}OCH{sub 3}) can provide an alternative approach toward efficient, ultra-clean and quiet compression ignition (CI) engines. From a combustion point of view, DME is an attractive alternative fuel for CI engines, primarily for commercial applications in urban areas, where ultra-low emissions will be required in the future. DME can resolve the classical diesel emission problem of smoke emissions, which are completely eliminated. With a properly developed DME injection and combustion system, NO{sub x} emissions can be reduced to 40% of Euro II or U.S. 1998 limits, and can meet the future ULEV standards of California. Simultaneously, the combustion noise is reduced by as much as 15 dB(A) below diesel levels. In addition, the classical diesel advantages such as high thermal efficiency, compression ignition, engine robustness, etc., are retained.

  7. Vibronic Coupling in a Flexible Bichromophore: 1,2-DIPHENOXYETHANE

    NASA Astrophysics Data System (ADS)

    Buchanan, Evan G.; Zwier, Timothy S.; Plusquellic, David F.

    2012-06-01

    Investigations of isolated flexible bichromophores through single conformation spectrocopy have provided tremendous insights into the intrinsic properties of close lying, vibronically coupled electronic states. However, the S2 origin is often elusive, requiring a gambit of experimental techniques aided by high level calculations to pin down its location and the excitonic splitting. Here, we expand our studies on flexible bichromophores to 1,2-diphenoxyethane (C6H5-O-CH2-CH2-O-C6H5, DPOE). Ultraviolet hole-burning identified two confomrers present in the supersonic jet expansion with C2h and C2 symmetry. Both experimental and computational results suggest a small excitonic splitting of no more than a few cm-1. The vibrationally and rotationally resolved spectra of DPOE conformational isomers will be discussed with regard to the vibronic coupling and excitonic splitting. Finally, the perturbation to the DPOE excited states due to a single water molecule will be discussed.

  8. Nitrogen fixation to cyanide at a molybdenum center.

    PubMed

    Curley, John J; Cozzolino, Anthony F; Cummins, Christopher C

    2011-03-21

    Facile methoxymethylation of N(2)-derived nitride NMo(N[(t)Bu]Ar)(3) provided the imido cation [MeOCH(2)NMo(N[(t)Bu]Ar)(3)](+) as its triflate salt in 88% yield. Treatment of the latter with LiN(SiMe(3))(2) provided blue methoxyketimide complex MeO(H)CNMo(N[(t)Bu]Ar)(3) in 95% yield. Conversion of the latter to the terminal cyanide complex NCMo(N[(t)Bu]Ar)(3), which was the subject of a single-crystal X-ray diffraction study, was accomplished in 51% yield upon treatment with a combination of SnCl(2) and Me(2)NSiMe(3).

  9. Poly(ethylene glycol) self-assembled monolayer island growth.

    PubMed

    Rundqvist, Jonas; Hoh, Jan H; Haviland, David B

    2005-03-29

    Here, we report a study of the morphology and growth dynamics of a self-assembled monolayer (SAM) of the amide containing poly(ethylene glycol) (PEG) thiol (CH3O(CH2CH2O)17NHCO(CH2)2SH) on atomically flat Au(111) surfaces. SAM growth from a 20 muM ethanolic solution reveals island growth through three distinct steps: island nucleation, island growth, and coalescence. The coalescence-step, filling voids in the SAM, is by far slowest. The fine structure study reveals dendritic island formation, an observation which can be explained by attractive intermolecular interactions and surface diffusion-limited aggregation. We have also observed a change in the island height, which peaks during the island growth phase. This height change can be associated with a molecular conformational transition.

  10. Insertion of a spin crossover Fe(III) complex into an oxalate-based layered material: coexistence of spin canting and spin crossover in a hybrid magnet.

    PubMed

    Clemente-León, Miguel; Coronado, Eugeno; Giménez-López, M Carmen; Soriano-Portillo, Alejandra; Waerenborgh, João C; Delgado, Fernando S; Ruiz-Pérez, Catalina

    2008-10-06

    The syntheses, structures, and magnetic properties of the compounds of formula [Fe (III)(sal 2trien)] 2[Mn (II) 2(ox) 3].4H 2O.C 3H 7NO ( 1) and [In (III)(sal 2trien)] 2[Mn (II) 2(ox) 3].3H 2O.CH 3OH (2) are reported. The structure presents a homometallic 2D honeycomb anionic layer formed by Mn (II) ions linked through oxalate ligands and a cationic double layer of [Fe(sal 2trien)] (+) or [In(sal 2trien)] (+) complexes intercalated between the 2D oxalate network. The magnetic properties and Mössbauer spectroscopy of 1 indicate the coexistence of a magnetic ordering of the Mn(II) oxalate network that behaves as a weak ferromagnet and a gradual spin crossover of the intercalated [Fe(sal 2trien)] (+) complexes.

  11. Formaldehyde mediated proton-transport catalysis in the ketene-water radical cation CH2C(O)OH2+

    NASA Astrophysics Data System (ADS)

    Lee, Richard; Ruttink, Paul J. A.; Burgers, Peter C.; Terlouw, Johan K.

    2006-09-01

    Previous studies have shown that the solitary ketene-water ion CH2C(O)OH2+ (1) does not isomerize into CH2C(OH)2+ (2), its more stable hydrogen shift isomer. Tandem mass spectrometry based collision experiments reveal that this isomerization does take place in the CH2O loss from low-energy 1,3-dihydroxyacetone ions (HOCH2)2CO+. A mechanistic analysis using the CBS-QB3 model chemistry shows that such molecular ions rearrange into hydrogen-bridged radical cations [CH2C(O)O(H)-H...OCH2]+ in which the CH2O molecule catalyzes the transformation 1 --> 2 prior to dissociation. The barrier for the unassisted reaction, 29 kcal mol-1, is reduced to a mere 0.6 kcal mol-1 for the catalysed transformation. Formaldehyde is an efficient catalyst because its proton affinity meets the criterion for facile proton-transport catalysis.

  12. Microwave Spectroscopy of Trans-Ethyl Methyl Ether in the Torsionally Excited State 3

    NASA Astrophysics Data System (ADS)

    Kobayashi, Kaori; Murata, Keigo; Tsunekawa, Shozo; Ohashi, Nobukimi

    2010-06-01

    The trans-ethyl methyl ether molecule (CH_3CH_2OCH_3) has two methyl group internal rotors which are equivalent to the two vibrational motions, ν28 and ν29. There is another low-lying torsional motion which is a skeltal torsion (ν30) and does not cause splitting. The microwave spectra of the trans-ethyl methyl ether molecule in the ν28 = 1, ν29 = 1, and ν30 = 1 have been studied and interactions between these states were discussed. In this paper we report results on the ν30 = 2, and 3 state. The analysis based on Hougen's tunneling matrix formulation considering two methyl groups are used. We try to interpret tunneling parameters obtained in the present analysis quantitatively from the viewpoint of torsion-torsion interaction.

  13. Theoretical study on the intracluster elimination channels for Mg+(CH3OH), Ca+(CH3OH), Mg+(NH3), and Ca+(NH3).

    PubMed

    Chan, Ka Wai; Wu, Yang; Liu, Zhi-Feng

    2008-09-18

    The intracluster elimination reactions in solvated alkaline earth metal monocation clusters, M (+)L n , are known to be size-dependent, indicating links between chemical reactivity and the solvation environment controlled by the cluster size. For the methanol and ammonia clusters, there are a number of competing elimination channels involving the breaking of O-H, C-H, O-CH 3, or N-H bond. In this report, we focus on the four clusters with only one solvent molecule and systematically map out the reaction paths and intermediates. The interaction between the metal ion and the departing H atom or CH 3 group varies considerably, depending on the interaction between the metal ion and the remaining group. The understanding of the nature of these interactions and the evaluation of various theoretical levels in treating these reactions provide a solid base for the investigation of the solvation effects on the chemical reactivity of the larger clusters.

  14. Solvated Electrons in Clusters: Magic Numbers for the Photoelectron Anisotropy.

    PubMed

    West, Adam H C; Yoder, Bruce L; Luckhaus, David; Signorell, Ruth

    2015-12-17

    This paper reports on a curiosity concerning magic numbers in neutral molecular clusters, namely on magic numbers related to the photoelectron anisotropy in angle-resolved photoelectron spectra. With a combination of density functional calculations and experiment, we search for magic numbers in Na(H2O)n, Na(NH3)n, Na(CH3OH)n, and Na(CH3OCH3)n clusters. In clusters of high symmetry, the highest occupied molecular orbital can be delocalized over an extended region, forming a symmetric charge distribution of high s character, which results in a pronounced anisotropy in the photoelectron angular distribution. We find magic numbers at n = 6 and 4 for sodium-doped dimethyl ether and ammonia clusters, respectively, but not for sodium-doped water and methanol clusters, which is likely a consequence of the degree of hydrogen bonding and the number of structural isomers.

  15. H-D exchange in metal carbene complexes: Structure of cluster (μ-H)(μ-OCD3)Os3(CO)9{:C(CD3)NC2H8O}

    NASA Astrophysics Data System (ADS)

    Savkov, Boris; Maksakov, Vladimir; Kuratieva, Natalia

    2015-10-01

    X-ray and spectroscopic data for the new complex (μ-H)(μ-OCH3)Os3(CO)9{:C(CD3)NC2H8O} (2) obtained in the reaction of the (μ-H)(μ-Cl)Os3(CO)9{:C(CH3)NC2H8O} (1) with NaOCD3 in CD3OD solution are reported. It is shown that cluster 1 has the property of CH-acidity inherent of Fisher type carbenes. This had demonstrated using hydrogen deuterium exchange reaction in the presence of a strong base. Bridging chlorine to metoxide ligand substitution takes place during the reaction. The molecular structure of 2 is compared with known analogues.

  16. Magnetic exchange interaction in the μ-hydroxo bridged vanadium(IV) dimers: a density functional theory combined with broken-symmetry approach

    NASA Astrophysics Data System (ADS)

    Zhang, Lei; Chen, Zhida

    2001-09-01

    Magnetic exchange interaction for the μ-hydroxo bridged vanadium(IV) dimers is investigated based on calculations of density functional theory combined with the broken-symmetry approach. It is found that there is an exponential correlation between the V-O(hydroxo)-V angle, the V-O(hydroxo) distance and the exchange coupling constants J. Meanwhile, the calculated results reveal that the deprotonation of the bridging hydroxo ligand causes a sharp increase of the exchange coupling interaction, but the magnetic coupling constant J is insensitive to the deprotonation of the bridging aquo ligand. Moreover, simplifying each 1,2-bridging squarate ligand with two -OCH 2 groups almost does not influence magnetic exchange behavior between the two vanadium(IV) ions, and the principle of the shortest superexchange pathway is available for the multiplicity of the bridging ligand in the μ-hydroxo bridged vanadium(IV) dimers.

  17. Photochemistry of Surface-Confined Mononuclear and Trinuclear Ruthenium Carbonyl Complexes. Direct Evidence for the Ability to Isolate Photogenerated Intermediates from each other on High Surface Area Silica.

    DTIC Science & Technology

    1982-01-04

    foned: [S -LRu(C0) 4 under 355 nm + 20 nm irradiation yields [S-LRu(CO) 3L’ (L’ = 13CO, PPh 3, P(OCH 2)3CCH 2CH3) when suspended in isooctane ...UUTY CLASSIVICATIO4 OF THIS PAGtI[(Wh- 000m ZrL-e0m - L’ [S4-L3Ru,(CO)g, suspended in isooctane , yields [S -LRu(CO)d when irradiated at 436 nm uner...erate [S.-L Ru (CO)g when isooctane solutions are purged with N2 to remove CO.The [S+-LRu{CO) 4 formed by reacting SiO 2 with C(EtO)3SiCH2CH2PP i ]Ru

  18. Production of the hydrogen by methane steam reforming over nickel catalysts prepared from hydrotalcite precursors

    NASA Astrophysics Data System (ADS)

    Fonseca, Alessandra; Assaf, Elisabete M.

    Catalysts were prepared from hydrotalcite precursors, characterized and tested in the reaction of methane steam reforming to produce hydrogen. The precursors were synthesized by: the traditional technique, with co-precipitation of Ni, Mg and Al nitrates with carbonate; co-precipitation of Mg and Al nitrates with pre-synthesized nickel chelate and anion-exchange of NO 3- of hydrotalcite with nickel chelate. The oxides were analyzed using atomic absorption spectrophotometry, specific surface area, X-ray diffraction (XRD), temperature programmed reduction (TPR) with H 2, catalytic tests and elemental analysis. The catalytic tests demonstrated high methane conversion, high activity for hydrogen production and high stability during the time of reaction for a molar ratio in the feed H 2O:CH 4 = 2:1.

  19. Methane/steam reforming kinetics for solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Achenbach, E.; Riensche, E.

    Experiments have been carried out to determine the kinetics of the methane/steam reforming process at anode materials of a solid oxide fuel cell. A nickel cermet was applied consisting of 80 wt.% ZrO 2 and 20 wt.% Ni. The temperature was varied from 700 to 940 °C, the CH 4 partial pressure from 0.11 to 0.33 bar, and the system pressure from 1.1 to 2.8 bar. The influence of the ratio H 2O/CH 4 was studied, in particular, by increasing this quantity from 2.6 to 8. The tests showed that, within the accuracy of the data, no effect of the H 2O partial pressure on the catalytic reforming process could be observed. Due to the high conversion rates of CH 4 at high temperatures, however, mass-transfer effects occurred, that must be taken into account when evaluating the steam-reforming data.

  20. Intramolecular structure and dynamics of mequinol and guaiacol in the gas phase: Rotationally resolved electronic spectra of their S1 states.

    PubMed

    Ruiz-Santoyo, José Arturo; Rodríguez-Matus, Marcela; Cabellos, José Luis; Yi, John T; Pratt, David W; Schmitt, Michael; Merino, Gabriel; Álvarez-Valtierra, Leonardo

    2015-09-07

    The molecular structures of guaiacol (2-methoxyphenol) and mequinol (4-methoxyphenol) have been studied using high resolution electronic spectroscopy in a molecular beam and contrasted with ab initio computations. Mequinol exhibits two low frequency bands that have been assigned to electronic origins of two possible conformers of the molecule, trans and cis. Guaiacol also shows low frequency bands, but in this case, the bands have been assigned to the electronic origin and vibrational modes of a single conformer of the isolated molecule. A detailed study of these bands indicates that guaiacol has a vibrationally averaged planar structure in the ground state, but it is distorted along both in-plane and out-of-plane coordinates in the first electronically excited state. An intramolecular hydrogen bond involving the adjacent   -OH and   -OCH3 groups plays a major role in these dynamics.

  1. The metamorphosis of heterometallic trinuclear antiferromagnetic complexes into nano-sized superparamagnetic spinels

    PubMed Central

    Vasylenko, Inna V.; Gavrylenko, Konstiantyn S.; Il’yin, Vladimir G.; Golub, Vladimir; Goloverda, Galina; Kolesnichenko, Vladimir; Addison, Anthony W.; Pavlishchuk, Vitaly V.

    2010-01-01

    Thermal decomposition of the trinuclear heterometallic oxoacetates [Fe2M(μ3-O)(CH3COO)6(H2O)3] has been used as a single-precursor method for synthesis of the spinel-structured ternary oxides MFe2O4 (M = MnII, CoII, and NiII). This facile process occurring at 320 °C results in the formation of nanocrystalline, (7–20 nm) highly pure stoichiometric ferrites in quantitative yield. The magnetic properties of these nanoparticulate ferrites were studied in the 10–300 K temperature range, revealing superparamagnetic behaviour for the Ni and Mn particles and ferromagnetic behavior for the Co ones at room temperature. Their blocking temperatures follow the order: CoFe2O4 > MnFe2O4 > NiFe2O4. PMID:20824196

  2. The metamorphosis of heterometallic trinuclear antiferromagnetic complexes into nano-sized superparamagnetic spinels.

    PubMed

    Vasylenko, Inna V; Gavrylenko, Konstiantyn S; Il'yin, Vladimir G; Golub, Vladimir; Goloverda, Galina; Kolesnichenko, Vladimir; Addison, Anthony W; Pavlishchuk, Vitaly V

    2010-05-15

    Thermal decomposition of the trinuclear heterometallic oxoacetates [Fe(2)M(μ(3)-O)(CH(3)COO)(6)(H(2)O)(3)] has been used as a single-precursor method for synthesis of the spinel-structured ternary oxides MFe(2)O(4) (M = Mn(II), Co(II), and Ni(II)). This facile process occurring at 320 °C results in the formation of nanocrystalline, (7-20 nm) highly pure stoichiometric ferrites in quantitative yield. The magnetic properties of these nanoparticulate ferrites were studied in the 10-300 K temperature range, revealing superparamagnetic behaviour for the Ni and Mn particles and ferromagnetic behavior for the Co ones at room temperature. Their blocking temperatures follow the order: CoFe(2)O(4) > MnFe(2)O(4) > NiFe(2)O(4).

  3. Rapid three-step cleavage of RNA and DNA model systems promoted by a dinuclear Cu(II) complex in methanol. energetic origins of the catalytic efficacy.

    PubMed

    Lu, Zhong-Lin; Liu, C Tony; Neverov, Alexei A; Brown, R Stan

    2007-09-19

    A dinuclear Cu(II) complex of 1,3-bis-N(1)-(1,5,9-triazacyclododecyl)propane with an associated methoxide (2-Cu(II)(2):(-OCH(3))) was prepared, and its kinetics of reaction with an RNA model (2-hydroxypropyl-p-nitrophenyl phosphate (1, HPNPP)) and two DNA models (methyl p-nitrophenyl phosphate (3) and iso-butyl p-chlorophenyl phosphate (4)) were studied in methanol solution at (s)(s)pH 7.2 +/- 0.2. X-ray diffraction structures of 2-Cu(II)(2):(-OH)(H(2)O)(CF(3)SO(3)-)(3):0.5CH(3)CH(2)OCH(2)CH(3) and 2-Cu(II)(2):(-OH)((C(6)H(5)CH(2)O)(2)PO(2)-)(CF(3)SO(3)-)2 show the mode of coordination of the bridging -OH and H(2)O between the two Cu(II) ions in the first complex and bridging -OH and phosphate groups in the second. The kinetic studies with 1 and 3 reveal some common preliminary steps prior to the chemical one of the catalyzed formation of p-nitrophenol. With 3, and also with the far less reactive substrate (4), two relatively fast events are cleanly observed via stopped-flow kinetics. The first of these is interpreted as a binding step which is linearly dependent on [catalyst] while the second is a unimolecular step independent of [catalyst] proposed to be a rearrangement that forms a doubly Cu(II)-coordinated phosphate. The catalysis of the cleavage of 1 and 3 is very strong, the first-order rate constants for formation of p-nitrophenol from the complex being approximately 0.7 s(-1) and 2.4 x 10(-3) s(-1), respectively. With substrate 3, 2-Cu(II)(2):(-OCH(3)) exhibits Michaelis-Mentin kinetics with a k(cat)/K(M) value of 30 M(-1) s(-1) which is 3.8 x 10(7)-fold greater than the methoxide promoted reaction of 3 (7.9 x 10(-7) M(-1) s(-1)). A free energy calculation indicates that the binding of 2-Cu(II)(2):(-OCH(3)) to the transition states for 1 and 3 cleavage stabilizes them by -21 and -24 kcal/mol, respectively, relative to that of the methoxide promoted reactions. The results are compared with a literature example where the cleavage of 1 in water is promoted by

  4. On the physical nature of halogen bonds: a QTAIM study.

    PubMed

    Syzgantseva, Olga A; Tognetti, Vincent; Joubert, Laurent

    2013-09-12

    In this article, we report a detailed study on halogen bonds in complexes of CHCBr, CHCCl, CH2CHBr, FBr, FCl, and ClBr with a set of Lewis bases (NH3, OH2, SH2, OCH2, OH(-), Br(-)). To obtain insight into the physical nature of these bonds, we extensively used Bader's Quantum Theory of Atoms-in-Molecules (QTAIM). With this aim, in addition to the examination of the bond critical points properties, we apply Pendás' Interacting Quantum Atoms (IQA) scheme, which enables rigorous and physical study of each interaction at work in the formation of the halogen-bonded complexes. In particular, the influence of primary and secondary interactions on the stability of the complexes is analyzed, and the roles of electrostatics and exchange are notably discussed and compared. Finally, relationships between QTAIM descriptors and binding energies are inspected.

  5. Treatment of dilute clusters of methanol and water by ab initio quantum mechanical calculations.

    PubMed

    Ruckenstein, Eli; Shulgin, Ivan L; Tilson, Jeffrey L

    2005-02-10

    Large molecular clusters can be considered as intermediate states between gas and condensed phases, and information about them can help us understand condensed phases. In this paper, ab initio quantum mechanical methods have been used to examine clusters formed of methanol and water molecules. The main goal was to obtain information about the intermolecular interactions and the structure of methanol/water clusters at the molecular level. The large clusters (CH(4)O...(H(2)O)(12) and H(2)O...(CH(4)O)(10)) containing one molecule of one component (methanol or water) and many (12, 10) molecules of the other component were considered. Møller-Plesset perturbation theory (MP2) was used in the calculations. Several representative cluster geometries were optimized, and nearest-neighbor interaction energies were calculated for the geometries obtained in the first step. The results of the calculations were compared to the available experimental information regarding the liquid methanol/water mixtures and to the molecular dynamics and Monte Carlo simulations, and good agreement was found. For the CH(4)O...(H(2)O)(12) cluster, it was shown that the molecules of water can be subdivided into two classes: (i) H bonded to the central methanol molecule and (ii) not H bonded to the central methanol molecule. As expected, these two classes exhibited striking energy differences. Although they are located almost the same distance from the carbon atom of the central methanol molecule, they possess very different intermolecular interaction energies with the central molecule. The H bonding constitutes a dominant factor in the hydration of methanol in dilute aqueous solutions. For the H(2)O...(CH(4)O)(10) cluster, it was shown that the central molecule of water has almost three H bonds with the methanol molecules; this result differs from those in the literature that concluded that the average number of H bonds between a central water molecule and methanol molecules in dilute solutions of

  6. Extraction processes and solvents for recovery of cesium, strontium, rare earth elements, technetium and actinides from liquid radioactive waste

    DOEpatents

    Zaitsev, Boris N.; Esimantovskiy, Vyacheslav M.; Lazarev, Leonard N.; Dzekun, Evgeniy G.; Romanovskiy, Valeriy N.; Todd, Terry A.; Brewer, Ken N.; Herbst, Ronald S.; Law, Jack D.

    2001-01-01

    Cesium and strontium are extracted from aqueous acidic radioactive waste containing rare earth elements, technetium and actinides, by contacting the waste with a composition of a complex organoboron compound and polyethylene glycol in an organofluorine diluent mixture. In a preferred embodiment the complex organoboron compound is chlorinated cobalt dicarbollide, the polyethylene glycol has the formula RC.sub.6 H.sub.4 (OCH.sub.2 CH.sub.2).sub.n OH, and the organofluorine diluent is a mixture of bis-tetrafluoropropyl ether of diethylene glycol with at least one of bis-tetrafluoropropyl ether of ethylene glycol and bis-tetrafluoropropyl formal. The rare earths, technetium and the actinides (especially uranium, plutonium and americium), are extracted from the aqueous phase using a phosphine oxide in a hydrocarbon diluent, and reextracted from the resulting organic phase into an aqueous phase by using a suitable strip reagent.

  7. Study of Edge Effect to Stop Liquid Spillage for Microgravity Application

    NASA Astrophysics Data System (ADS)

    Grishaev, Viktor; Amirfazli, A.; Chikov, Sergey; Lyulin, Yuriy; Kabov, Oleg

    2013-02-01

    The ability of a micro-groove to prevent the spreading of HFE-7100 fluid (C4F9OCH3) having low surface tension (γ = 13.6 mN/m) on a surface is studied. In this study, micro-grooves were made around square openings of a plate made of either polycarbonate or 316 stainless steel. To verify effectiveness of micro-grooves to stop the spread of HFE-7100, experiments were done under non-saturated and saturated conditions. Under non-saturated conditions the micro-grooves on both materials confined the liquid up to apparent angle of 55 ± 5° due to the edge effect. Saturated gas-vapor mixture with vapor mass fraction of w v = 88% and w v = 97% did not significantly influence the confinement of the liquid by the micro-groove. This result is promising for application of micro-grooved plates in CIMEX experiment planned for ISS.

  8. Synthesis, characterization and anticancer evaluation of novel tri-arm star shaped 1,3,5-triazine hydrazones

    NASA Astrophysics Data System (ADS)

    Machakanur, Shrinath S.; Patil, Basavaraj R.; Badiger, Dayananda S.; Bakale, Raghavendra P.; Gudasi, Kalagouda B.; Annie Bligh, S. W.

    2012-03-01

    A series of novel trisubstituted triazine hydrazones [N3C3(sbnd OC6H4-p-CHdbnd Nsbnd NHsbnd C(O)sbnd C6H4-p-X)3] (X = H, Br, Cl, F, OH, OCH3, CH3, NO2, NH2) were prepared by a three-fold condensation reaction of 2,4,6-tris(4-formylphenoxy)-1,3,5-triazine with p-substituted benzoic acid hydrazides [NH2sbnd NHsbnd C(O)sbnd C6H4-p-X] with excellent yields. The structures were confirmed by elemental analysis, FT-IR, 1H, 13C, 2D-HSQC NMR and mass spectrometry (MALDI-TOF). These derivatives bearing hydrolysable hydrazone linkages were evaluated for their invitro antiproliferative activity against the human liver carcinoma cell line (HepG2) and human cervix carcinoma cell line (HeLa).

  9. Thermodynamic properties (enthalpy, bond energy, entropy, and heat capacity) and internal rotor potentials of vinyl alcohol, methyl vinyl ether, and their corresponding radicals.

    PubMed

    da Silva, Gabriel; Kim, Chol-Han; Bozzelli, Joseph W

    2006-06-29

    Vinyl alcohols (enols) have been discovered as important intermediates and products in the oxidation and combustion of hydrocarbons, while methyl vinyl ethers are also thought to occur as important combustion intermediates. Vinyl alcohol has been detected in interstellar media, while poly(vinyl alcohol) and poly(methyl vinyl ether) are common polymers. The thermochemical property data on these vinyl alcohols and methyl vinyl ethers is important for understanding their stability, reaction paths, and kinetics in atmospheric and thermal hydrocarbon-oxygen systems. Enthalpies , entropies , and heat capacities (C(p)()(T)) are determined for CH(2)=CHOH, C(*)H=CHOH, CH(2)=C(*)OH, CH(2)=CHOCH(3), C(*)H=CHOCH(3), CH(2)=C(*)OCH(3), and CH(2)=CHOC(*)H(2). Molecular structures, vibrational frequencies, , and C(p)(T) are calculated at the B3LYP/6-31G(d,p) density functional calculation level. Enthalpies are also determined using the composite CBS-Q, CBS-APNO, and G3 methods using isodesmic work reactions to minimize calculation errors. Potential barriers for internal rotors are calculated at the B3LYP/6-31G(d,p) level and used to determine the hindered internal rotational contributions to entropy and heat capacity. The recommended ideal gas phase values calculated in this study are the following (in kcal mol(-1)): -30.0, -28.9 (syn, anti) for CH(2)=CHOH; -25.6, -23.9 for CH(2)=CHOCH(3); 31.3, 33.5 for C(*)H=CHOH; 27.1 for anti-CH(2)=C(*)OH; 35.6, 39.3 for C(*)H=CHOCH(3); 33.5, 32.2 for CH(2)=C(*)OCH(3); 21.3, 22.0 for CH(2)=CHOC(*)H(2). Bond dissociation energies (BDEs) and group additivity contributions are also determined. The BDEs reveal that the O-H, O-CH(3), C-OH, and C-OCH(3) bonds in vinyl alcohol and methyl vinyl ether are similar in energy to those in the aromatic molecules phenol and methyl phenyl ether, being on average around 3 kcal mol(-1) weaker in the vinyl systems. The keto-enol tautomerization enthalpy for the interconversion of vinyl alcohol to acetaldehyde is

  10. Preparative separation of glycoalkaloids α-solanine and α-chaconine by centrifugal partition chromatography.

    PubMed

    Attoumbré, Jacques; Lesur, David; Giordanengo, Philippe; Baltora-Rosset, Sylvie

    2012-11-01

    The main glycoalkaloids of a commercial potato cultivar, α-chaconine and α-solanine, were extracted from sprouts of Solanum tuberosum cv. Pompadour by a mixture of MeOH/H(2)O/CH(3)COOH (400/100/50, v/v/v). In these conditions, 2.8±0.62g of crude extract were obtained from 50g of fresh sprouts and the total glycoalkaloid content was determined by analytical HPLC at 216.5mg/100g. α-Chaconine and α-solanine were separated in a preparative scale using centrifugal partition chromatography (CPC). In a solvent system composed of a mixture of ethyl acetate/butanol/water (15/35/50, v/v/v), α-chaconine (54mg) and α-solanine (15mg) were successfully isolated from the crude extract in one step of purification. The purity of isolated compounds was determined to be higher than 92% by HPLC analysis.

  11. Side Group Addition to the PAH Coronene by UV Photolysis in Cosmic Ice Analogs

    NASA Technical Reports Server (NTRS)

    Bernstein, Max P.; Elsila, Jamie E.; Dworkin, Jason P.; Sandford, Scott A.; Allamandola, Louis J.; Zare, Richard N.; DeVincenzi, D. (Technical Monitor)

    2002-01-01

    Ultraviolet photolysis of various ice mixtures at low temperature and pressure caused the addition of amino (-NH2), methyl (-CH3), methoxy (-OCH3), and cyano (-CN) functional groups to the polycyclic aromatic hydrocarbon (PAH) coronene (C22H12). The implications of these results for interstellar and meteoritic chemistry are discussed. Previously only simple PAH photo-oxidation had been reported. This work represents the first experimental evidence that ice photochemistry may have contributed to aromatics bearing carbon and nitrogen containing side groups that are detected in primitive meteorites and interplanetary dust particles. Furthermore, these results suggest a wider range of modified PAHs should be expected in interstellar lees and materials predating solar system formation.

  12. An ab initio study on anionic aerogen bonds

    NASA Astrophysics Data System (ADS)

    Esrafili, Mehdi D.; Mohammadian-Sabet, Fariba

    2017-01-01

    An ab initio study is carried out to investigate the anionic aerogen bonds in complexes of KrO3, XeO3 and XeOF2 with F-, Cl-, Br-, CN-, NC-, N3-, SH-, SCN-, NCS-, OH- and OCH3- anions. All of the anionic aerogen bonds analyzed here have a partial covalent character. Charge transfer from the anion to the Kr-O or Xe-O σ∗ orbital stabilizes these complexes and leads to a sizable redshift in the corresponding stretching frequencies. The J(Kr-O) or J(Xe-O) spin-spin coupling constants can be regarded as a useful tool for the characterization of strength of the anionic aerogen-bonded complexes.

  13. Digitally Controlled Analog Signal Processing

    DTIC Science & Technology

    1988-04-01

    TO TEST7 CMPA #81H SEQ TS SET-8. GO TO TESTS CMPA #9H BEQ T9 SET-9 GO TO TEST9 CMPA #eAH BEO TIS SET-IS GOTO TESTIS CMPA jesH SEQ TII SET-I1 GOTO...TEST11 CMPA lOCH BEQ T12 SET-12 GOTO TEST12 CMPA #0DH BEQ T13 SET-13 GOTO TEST13 A 0eHBEO T14 SET-14 GOTO TEST14 CMPA eIFH SEQ T15 SET-15 GOTO TESTIS ...TESTS T9 imp TEST9 TIO imp TESTIS T11 imp TESTII T12 imp TEST12 T13 imp TEST13 T14 imp TEST14 TIS Jip TEST15 TESTS LDAA OeeH LOOPS STAA PORT4 NOP NOP STAB

  14. Radical-scavenging activity of natural methoxyphenols vs. synthetic ones using the induction period method.

    PubMed

    Kadoma, Yoshinori; Atsumi, Toshiko; Okada, Norihisa; Ishihara, Mariko; Yokoe, Ichiro; Fujisawa, Seiichiro

    2007-02-03

    The radical-scavenging activities of the synthetic antioxidants 2-allyl-4-X-phenol (X = NO2, Cl, Br, OCH3, COCH3, CH3, t-(CH3)3, C6H5) and 2,4-dimethoxyphenol, and the natural antioxidants eugenol and isoeugenol, were investigated using differential scanning calorimetry (DSC) by measuring their anti-1,1-diphenyl-2-picrylhydrazyl (DPPH) radical activity and the induction period for polymerization of methyl methacrylate (MMA) initiated by thermal decomposition of 2,2'-azobisisobutyronitrile (AIBN) and benzoyl peroxide (BPO). 2-Allyl-4-methoxyphenol and 2,4-dimethoxy-phenol scavenged not only oxygen-centered radicals (PhCOO*) derived from BPO, but also carbon-centered radicals (R*) derived from the AIBN and DPPH radical much more efficiently, in comparison with eugenol and isoeugenol. 2-Allyl-4-methoxyphenol may be useful for its lower prooxidative activity.

  15. Improvements in bis(cyclopentadienyl)magnesium purity as determined with gas chromatography-mass spectroscopy

    SciTech Connect

    BARTRAM,MICHAEL E.

    2000-03-08

    Bis(cyclopentadienyl)magnesium (MgCp2) is used commonly as a source for doping nitride materials with magnesium. Increased oxygen incorporation known to accompany the use of MgCp2 makes the purity of this precursor an important consideration in nitride CVD. Gas chromatography-mass spectroscopy (GCMS) methods have now been developed for the identification of volatile impurities in MgCp2. Diethylether, an oxygen containing organic compound (CH{sub 3}CH{sub 2}OCH{sub 2}CH{sub 3}), and additional organic impurities were found in the MgCp2 supplied by three manufacturers. Subsequent refinements in the synthetic processes by these companies have resulted in the availability of MgCp2 free of ether and other organic impurities as determined by GCMS.

  16. Flexibility and sorption selectivity in rigid metal-organic frameworks: the impact of ether-functionalised linkers.

    PubMed

    Henke, Sebastian; Schmid, Rochus; Grunwaldt, Jan-Dierk; Fischer, Roland A

    2010-12-27

    The functionalisation of well-known rigid metal-organic frameworks (namely, [Zn(4)O(bdc)(3)](n), MOF-5, IRMOF-1 and [Zn(2)(bdc)(2)(dabco)](n); bdc = 1,4-benzene dicarboxylate, dabco = diazabicyclo[2.2.2]octane) with additional alkyl ether groups of the type -O-(CH(2))(n)-O-CH(3) (n = 2-4) initiates unexpected structural flexibility, as well as high sorption selectivity towards CO(2) over N(2) and CH(4) in the porous materials. These novel materials respond to the presence/absence of guest molecules with structural transformations. We found that the chain length of the alkyl ether groups and the substitution pattern of the bdc-type linker have a major impact on structural flexibility and sorption selectivity. Remarkably, our results show that a high crystalline order of the activated material is not a prerequisite to achieve significant porosity and high sorption selectivity.

  17. Organic solids produced from simple C/H/O/N ices by charged particles - Applications to the outer solar system

    NASA Technical Reports Server (NTRS)

    Khare, B. N.; Thompson, W. R.; Chyba, C. F.; Sagan, C.; Arakawa, E. T.

    1989-01-01

    The effects of charged particle irradiation by cold plasma discharge on surfaces of H2O:CH4 clathrate with a 200:1 ratio and on ices composed of H2O and C2H6 or C2H2 are examined. The molecules studies are found in Comet Halley and are plausible constituents in icy outer solar system objects. The IR transmission spectra of four ice-tholin residues obtained in the laboratory are compared with spectra produced by irradiation of gases and ices containing simple hydrocarbons. The similarities between CH4 clathrate residue and Halley organic grains, and the surface transport or atmospheric replenishment activity on Triton and Pluto are discussed.

  18. Improved mechanical properties of HDPE/nano-alumina composite through silane coupling agent

    NASA Astrophysics Data System (ADS)

    Akmil, N.; Luqman, C. A.; Ahmad, M.; Zaman, K.

    2012-11-01

    The effect of silane coupling agent to mechanical properties of HDPE/nano-alumina composite was investigated. Nano-alumina used in this study was produced by using sol-gel method. The shape and size of nano-alumina were determined by using TEM. Prior to the usage of nano alumina as a filler in the polymer matrix, (3-methacryloxypropyl) trimethoxysilane (MPS) was used to functionalize the nanoparticles due to its bifunctional nature: hydrolysable group (-Si(OCH3)3) and unsaturated carbon-carbon double bond. The XRD result shows diffraction spectrum of the synthesized nano-alumina. In order to improve the mechanical properties of the composite, nanoalumina was treated with (3-methacryloxypropyl) trimethoxysilane (MPS). A high tensile strength, is achieved at 4 wt% of MPS.

  19. Differential adsorption of complex organic molecule isomers on interstellar ice surfaces

    NASA Astrophysics Data System (ADS)

    Bertin, M.; Michaut, X.; Lattelais, M.; Mokrane, H.; Pauzat, F.; Pilmé, J.; Minot, C.; Ellinger, Y.; Romanzin, C.; Jeseck, P.; Fillion, J.-H.; Chaabouni, H.; Congiu, E.; Dulieu, F.; Baouche, S.; Lemaire, J.-L.

    2012-02-01

    We present a combined theoretical and experimental study of the adsorption of two pairs of organic isomers, (i) acetic acid AA (CH3COOH) and methyl formate MF (HCOOCH3), and (ii) ethanol EtOH (CH3CH2OH) and dimethyl ether DME (CH3OCH3), onto crystalline water ice surfaces at low temperatures. Both approaches show that, for each pair, the most stable isomer from a thermodynamical point of view, i.e. AA and EtOH, is also the one which is the more tightly bound to the water ice surface compared to the less stable isomers (MF and DME). This finding, which can be explained by the ability of AA or EtOH to efficiently interact with the ice surface via hydrogen bondings, may have important consequences in an astrophysical context, since it could explain why the most stable isomer is not the most abundant observed in the interstellar gas phase.

  20. 13C CP MAS NMR and GIAO-CHF/DFT calculations of flavonoids: Morin, kaempferol, tricin, genistein, formononetin and 3,7-dihydroxyflavone

    NASA Astrophysics Data System (ADS)

    Zielińska, Agnieszka; Paradowska, Katarzyna; Jakowski, Jacek; Wawer, Iwona

    2008-02-01

    13C CP MAS NMR spectra of the flavonoids: morin, kaempferol, 3,7-dihydroxyflavone, tricin and isoflavones: genistein and formononetin were recorded to characterize solid-state conformations. Intramolecular hydrogen bonds forming five-, six- and seven-membered rings are present in the two morin molecules in the crystals - their 13C resonances have been assigned with the aid of the calculated shielding constants. Linear relationships between the calculated shielding constants σDFT (ppm) and chemical shifts ( δCPMAS, ppm) were obtained for all studied compounds. Higher correlation coefficients suggest that the conformation with "clockwise" orientation of both OH groups is more probable in the solid 3,7-dihydroxyflavone, whereas in the solid formononetin the OH and OCH 3 substituents are directed "anticlockwise". The barrier to the rotation of phenyl ring B decreases in the order: morin (2'-OH, 3-OH) > kaempferol (3-OH) > tricin.

  1. Role of water and carbonates in photocatalytic transformation of CO{sub 2} to CH{sub 4} on titania.

    SciTech Connect

    Dimitrijevic, N. M.; Vijayan, B. K.; Poluektov, O. G.; Rajh, T.; Gray, K. A.; He, H.; Zapol, P.

    2011-02-24

    Using the electron paramagnetic resonance technique, we have elucidated the multiple roles of water and carbonates in the overall photocatalytic reduction of carbon dioxide to methane over titania nanoparticles. The formation of H atoms (reduction product) and {center_dot}OH radicals (oxidation product) from water, and CO{sub 3}{sup -} radical anions (oxidation product) from carbonates, was detected in CO{sub 2}-saturated titania aqueous dispersion under UV illumination. Additionally, methoxyl, {center_dot}OCH{sub 3}, and methyl, {center_dot}CH{sub 3}, radicals were identified as reaction intermediates. The two-electron, one-proton reaction proposed as an initial step in the reduction of CO{sub 2} on the surface of TiO{sub 2} is supported by the results of first-principles calculations.

  2. Role of Water and Carbonates in Photocatalytic Transformation of CO2 to CH4 on Titania

    SciTech Connect

    Dimitrijevic, Nada; Vijayan, Baiju K.; Poluektov, Oleg G.; Rajh, Tijana; Gray, Kimberley A.; He, Haiying; Zapol, Peter

    2011-03-23

    Using the electron paramagnetic resonance technique, we have elucidated the multiple roles of water and carbonates in the overall photocatalytic reduction of carbon dioxide to methane over titania nanoparticles. The formation of H atoms (reduction product) and {sm_bullet}OH radicals (oxidation product) from water, and CO{sub 3}{sup -} radical anions (oxidation product) from carbonates, was detected in CO{sub 2}-saturated titania aqueous dispersion under UV illumination. Additionally, methoxyl, {sm_bullet}OCH{sub 3}, and methyl, {sm_bullet}CH{sub 3}, radicals were identified as reaction intermediates. The two-electron, one-proton reaction proposed as an initial step in the reduction of CO{sub 2}, on the surface of TiO{sub 2}, is supported by the results of first-principles calculations.

  3. Efficient Room-Temperature Methane Activation by the Closed-Shell, Metal-Free Cluster [OSiOH](+) : A Novel Mechanistic Variant.

    PubMed

    Sun, Xiaoyan; Zhou, Shaodong; Schlangen, Maria; Schwarz, Helmut

    2016-09-26

    The closed-shell cluster ion [OSiOH](+) is generated in the gas phase and its reactivity towards the thermal activation of CH4 has been examined using Fourier transform-ion cyclotron resonance (FT-ICR) mass spectrometry in conjunction with state-of-the-art quantum chemical calculations. Quite unexpectedly at room temperature, [OSiOH](+) efficiently mediates C-H bond activation, giving rise to [SiOH](+) and [SiOCH3 ](+) with the concomitant formation of methanol and water, respectively. Mechanistic aspects for this unprecedented reactivity pattern are presented, and the properties of the [OSiOH](+) /CH4 couple are compared with those of the closed-shell systems [OCOH](+) /CH4 and [MgOH](+) /CH4 ; the last two couples exhibit an entirely different reactivity scenario.

  4. In vivo methylation of guanine by the organophosphorus insecticide tetrachlorvinphos.

    PubMed

    Zayed, S M; Mostafa, I Y; Adam, Y; Hegazi, B

    1983-12-01

    The in vivo methylating capability of the organophosphorus insecticide tetrachlorvinphos, assayed by the formation of 7-methyl-guanine in mouse liver, was investigated. Following intraperitoneal injection of male mice with different doses of the 14C-insecticide, labelled at the OCH3 groups, the total and specific radioactivity of nucleic acids and protein were determined. The 14C-labelling in the isolated macromolecules reached its maximum 24 hours following administration of the insecticide. Analysis of the acid hydrolysate of DNA and of RNA on Dowex-50 WX-12 revealed the presence of (7-14C) methylguanine. At maximum 14C-labelling, the amount of radioactive 7-MeGu, calculated as fraction of total dose, was around 9 X 10(-5) and 39 X 10(-5) for DNA and RNA, respectively.

  5. Gas phase kinetics for the ozonolysis of n-butyl methacrylate, ethyl crotonate and vinyl propionate under atmospheric conditions

    NASA Astrophysics Data System (ADS)

    Gaona Colmán, Elizabeth; Blanco, María B.; Barnes, Ian; Teruel, Mariano A.

    2013-07-01

    Rate coefficients for the reactions of ozone with n-butyl methacrylate, ethyl crotonate and vinyl propionate have been determined at 298 ± 1 K and atmospheric pressure. The following room temperature rate coefficients (in cm3 molecule-1 s-1 units) were obtained: k1(O3 + CH2dbnd C(CH3)C(O)OC4H9) = (1.0 ± 0.3) × 10-17, k2(O3 + CH3CHdbnd CHC(O)OCH2CH3) = (8.0 ± 1.8) × 10-18 and k3(O3 + CH3CH2C(O)OCHdbnd CH2) = (5.3 ± 1.3) × 10-18. This is the first kinetic study for these reactions at atmospheric pressure. The effect of substituent groups on the overall rate coefficients is analyzed. Free energy relationships are presented and atmospheric lifetimes are discussed.

  6. Methanol in the sky with diamonds

    NASA Technical Reports Server (NTRS)

    Allamandola, L. J.; Sandford, S. A.; Tielens, A. G. G. M.; Herbst, T.

    1991-01-01

    The present of gas phase methanol in dense interstellar molecular clouds was established by radio detection of its rotational emission lines. However, the position, width, and profile of a absorption band near 1470 cm(exp -1) in the IR spectra of many dense molecular clouds strongly suggests that solid methanol is an important component of interstellar ices. In an attempt to better constrain the identification of 1470 cm(exp -1) feature, we began a program to search for other characteristic absorption bands of solid state methanol in the spectra of objects known to produce this band. One such feature is now identified in the spectra of several dense molecular clouds and its position, width, and profile fit well with those of laboratory H2O:CH3OH ices. Thus, the presence of methanol-bearing ices in space is confirmed.

  7. A novel route towards water-soluble luminescent iridium(iii) complexes via a hydroxy-bridged dinuclear precursor.

    PubMed

    Scarpelli, Francesca; Ionescu, Andreea; Ricciardi, Loredana; Plastina, Pierluigi; Aiello, Iolinda; La Deda, Massimo; Crispini, Alessandra; Ghedini, Mauro; Godbert, Nicolas

    2016-11-01

    The synthesis and photophysical characterization of a new family of luminescent water-soluble ionic iridium(iii) complexes of the general formula [(ppy)2Ir(bpy)]X are reported. The Ir(iii) complexes incorporate a cyclometalated 2-phenylpyridine (ppy), the ancillary ligand 2,2'-bipyridyl (bpy) and different counterions (X(-) = EtO(-), OH(-), EtOCH2CO2(-), MeOCH2CO2(-)). These complexes were obtained starting from the cyclometalated Ir(iii) chloro-bridged dimer [(ppy)2Ir(μ-Cl)]2, for the first time synthesized through a new microwave assisted synthetic procedure, and subsequently converted into the corresponding hydroxy-bridged dimer [(ppy)2Ir(μ-OH)]2. The latter was eventually used as a sole reagent for the synthesis of all the reported complexes by simply varying the nature of the reaction solvent from water to alcohols and glycol ethers. This study demonstrates the versatility of the [(ppy)2Ir(μ-OH)]2 complex as a precursor to water soluble ionic Ir(iii) complexes. Indeed, [(ppy)2Ir(μ-OH)]2 has shown its peculiar chemical reactivity due to both a strong base character and an unexpected oxidative ability towards the alcoholic function of glycol ethers. All the synthesized complexes exhibit, in water solution, an orange emission centred at 606 nm. Moreover, all complexes display the ability to give rise to gel phases in water upon increasing their concentration, and the photophysical study evidenced the various interactions governing the gelification process. The water-solubility of these new luminescent Ir(iii) complexes makes them potentially useful in bio-related systems.

  8. New 7-arylpiperazinylalkyl-8-morpholin-4-yl-purine-2,6-dione derivatives with anxiolytic activity - Synthesis, crystal structure and structure-activity study

    NASA Astrophysics Data System (ADS)

    Chłoń-Rzepa, Grażyna; Żmudzki, Paweł; Pawłowski, Maciej; Wesołowska, Anna; Satała, Grzegorz; Bojarski, Andrzej J.; Jabłoński, Mateusz; Kalinowska-Tłuścik, Justyna

    2014-06-01

    On the basis of our earlier studies with serotonin (5-HT) receptor ligands in the group of long-chain arylpiperazines (LCAPs), a new series of 7-arylpiperazinylalkyl-8-morpholin-4-yl-purine-2,6-dione derivatives (5-12) has been designed, synthesised and studied in vitro for their affinity for 5-HT1A, 5-HT2A, 5-HT6 and 5-HT7 receptors. The introduction of o-OCH3 and m-Cl into the phenylpiperazinyl moiety as well as the elongation of the linker between purine-2,6-dione core and arylpiperazine fragment modified the affinity for the tested 5-HT receptors. The structures of compounds 9-11 (hydrochloride salts) were confirmed by an X-ray diffraction method. All molecules adopted a different conformation in the crystal. The strongest observed type of interaction is a charge assisted hydrogen bond N+-H⋯Cl-. Additionally, the π-π interactions between 1,3-dimethyl-3,7-dihydropurine-2,6-dione cores of the neighbouring molecules were also observed. As it is observed in the presented crystal structures, the morpholine ring (a potential donor and acceptor of the hydrogen bonds) seems to be an attractive substituent, that may support binding to the non-specific sites of 5-HT receptors. Another interesting feature is the mutual orientation of rings in the arylpiperazine fragment, with plausible influence on ligand-receptor recognition. For compound 10, with strong 5-HT1A binding affinity, the mutual orientation of rings is determined by the intramolecular weak C-H⋯O hydrogen bond. This observation may contribute to a better understanding of the more selective binding of o-OCH3 arylpiperazine derivatives to the 5-HT1A receptor.

  9. Aluminum complexes derived from a hexadentate salen-type Schiff base: synthesis, structure, and catalysis for cyclic carbonate synthesis.

    PubMed

    Xu, Ya; Yuan, Dan; Wang, Yaorong; Yao, Yingming

    2017-04-12

    Different aluminum complexes were synthesized by the reaction of aluminum alkyls with a hexadentate salen-type Schiff base. The reaction of N,N'-bis(3,5-di-tert-butylsalicylidene)-2,2'-(ethylenedioxy)dianiline (LH2) with one equiv. of AlMe3 in toluene at 100 °C proceeded by methane elimination to produce the intermediate methyl complex [AlMeL] (1), and then subsequent intramolecular methyl migration to give the aluminum complex [AlL'] (2) [L' = (2-O-3,5-(t)Bu2C6H2)CH[double bond, length as m-dash]NC6H4OCH2CH2OC6H4NCH(Me)(2'-O-3',5'-(t)Bu2C6H2)]. The reaction of the same ligand with AlEt3 under the same experimental conditions involved ethane elimination, ethylene elimination and intramolecular hydrogen migration, and led to the complex [AlL''] (3) [L'' = (2-O-3,5-(t)Bu2C6H2)CH[double bond, length as m-dash]NC6H4OCH2CH2OC6H4NCH2(2'-O-3',5'-(t)Bu2C6H2)]. However, the interaction of two equivalents of AlMe3 and AlEt3 afforded the corresponding binuclear complexes [(AlMe2)2L] (4) and [(AlEt2)2L] (5), respectively, and no methyl or hydrogen migration was found. The solid-state structures of aluminum complexes 1-3 were determined by single-crystal X-ray diffraction. It was found that complexes 2-5 show a very effective catalytic activity for the cycloaddition of epoxides and CO2 in the presence of NBu4Br as a cocatalyst at atmospheric pressure.

  10. Comparison of the crystal structures of methyl 4-bromo-2-(meth-oxy-meth-oxy)benzoate and 4-bromo-3-(meth-oxy-meth-oxy)benzoic acid.

    PubMed

    Suchetan, P A; Suneetha, V; Naveen, S; Lokanath, N K; Krishna Murthy, P

    2016-04-01

    The title compounds, C10H11BrO4, (I), and C9H9BrO4, (II), are derivatives of bromo-hy-droxy-benzoic acids. Compound (II) crystallizes with two independent mol-ecules (A and B) in the asymmetric unit. In both (I) and (II), the O-CH2-O-CH3 side chain is not in its fully extended conformation; the O-C-O-C torsion angle is 67.3 (3) ° in (I), and -65.8 (3) and -74.1 (3)° in mol-ecules A and B, respectively, in compound (II). In the crystal of (I), mol-ecules are linked by C-H⋯O hydrogen bonds, forming C(5) chains along [010]. The chains are linked by short Br⋯O contacts [3.047 (2) Å], forming sheets parallel to the bc plane. The sheets are linked via C-H⋯π inter-actions, forming a three-dimensional architecture. In the crystal of (II), mol-ecules A and B are linked to form R 2 (2)(8) dimers via two strong O-H⋯O hydrogen bonds. These dimers are linked into ⋯A-B⋯A-B⋯A-B⋯ [C 2 (2)(15)] chains along [011] by C-H⋯O hydrogen bonds. The chains are linked by slipped parallel π-π inter-actions [inter-centroid distances = 3.6787 (18) and 3.8431 (17) Å], leading to the formation of slabs parallel to the bc plane.

  11. NMR shielding calculations across the periodic table: diamagnetic uranium compounds. 2. Ligand and metal NMR.

    PubMed

    Schreckenbach, Georg

    2002-12-16

    In this and a previous article (J. Phys. Chem. A 2000, 104, 8244), the range of application for relativistic density functional theory (DFT) is extended to the calculation of nuclear magnetic resonance (NMR) shieldings and chemical shifts in diamagnetic actinide compounds. Two relativistic DFT methods are used, ZORA ("zeroth-order regular approximation") and the quasirelativistic (QR) method. In the given second paper, NMR shieldings and chemical shifts are calculated and discussed for a wide range of compounds. The molecules studied comprise uranyl complexes, [UO(2)L(n)](+/-)(q); UF(6); inorganic UF(6) derivatives, UF(6-n)Cl(n), n = 0-6; and organometallic UF(6) derivatives, UF(6-n)(OCH(3))(n), n = 0-5. Uranyl complexes include [UO(2)F(4)](2-), [UO(2)Cl(4)](2-), [UO(2)(OH)(4)](2-), [UO(2)(CO(3))(3)](4-), and [UO(2)(H(2)O)(5)](2+). For the ligand NMR, moderate (e.g., (19)F NMR chemical shifts in UF(6-n)Cl(n)) to excellent agreement [e.g., (19)F chemical shift tensor in UF(6) or (1)H NMR in UF(6-n)(OCH(3))(n)] has been found between theory and experiment. The methods have been used to calculate the experimentally unknown (235)U NMR chemical shifts. A large chemical shift range of at least 21,000 ppm has been predicted for the (235)U nucleus. ZORA spin-orbit appears to be the most accurate method for predicting actinide metal chemical shifts. Trends in the (235)U NMR chemical shifts of UF(6-n)L(n) molecules are analyzed and explained in terms of the calculated electronic structure. It is argued that the energy separation and interaction between occupied and virtual orbitals with f-character are the determining factors.

  12. Molecular Characterization of Chromosomal Class C β-Lactamase and Its Regulatory Gene in Ochrobactrum anthropi

    PubMed Central

    Nadjar, David; Labia, Roger; Cerceau, Claude; Bizet, Chantal; Philippon, Alain; Arlet, Guillaume

    2001-01-01

    Ochrobactrum anthropi, formerly known as CDC group Vd, is an oxidase-producing, gram-negative, obligately aerobic, non-lactose-fermenting bacillus of low virulence that occasionally causes human infections. It is highly resistant to all β-lactams except imipenem. A clinical isolate, SLO74, and six reference strains were tested. MICs of penicillins, aztreonam, and most cephalosporins tested, including cefotaxime and ceftazidime, were >128 μg/ml and of cefepime were 64 to >128 μg/ml. Clavulanic acid was ineffective and tazobactam had a weak effect in association with piperacillin. Two genes, ampR and ampC, were cloned by inserting restriction fragments of genomic DNA from the clinical strain O. anthropi SLO74 into pBK-CMV to give the recombinant plasmid pBK-OA1. The pattern of resistance to β-lactams of this clone was similar to that of the parental strain, except for its resistance to cefepime (MIC, 0.5 μg/ml). The deduced amino acid sequence of the AmpC β-lactamase (pI, 8.9) was only 41 to 52% identical to the sequence of other chromosomally encoded and plasmid-encoded class C β-lactamases. The kinetic properties of this β-lactamase were typical for this class of β-lactamases. Upstream from the ampC gene, the ampR gene encodes a protein with a sequence that is 46 to 62% identical to those of other AmpR proteins and with an amino-terminal DNA-binding domain typical of transcriptional activators of the Lys-R family. The deduced amino acid sequences of the ampC genes of the six reference strains were 96 to 99% identical to the sequence of the clinical strain. The β-lactamase characterized from strain SLO74 was named OCH-1 (gene, blaOCH-I). PMID:11451692

  13. Influence of the temporal variations of plasma composition on the cyclic formation of dust in hexamethyldisiloxane-argon radiofrequency discharges: Analysis by time-resolved mass spectrometry

    NASA Astrophysics Data System (ADS)

    Despax, B.; Gaboriau, F.; Caquineau, H.; Makasheva, K.

    2016-10-01

    Cyclic formation of dust nanoparticles in hexamethyldisiloxane (HMDSO, Si2O(CH3)6)-argon RF discharge with pulsed injection of HMDSO was studied using time-resolved mass spectrometry (MS) and optical emission spectroscopy (OES). A large amount of C2H2, considered as promoter of dust nucleation in hydrocarbon plasmas, was found as a by-product of HMDSO fragmentation. Although no negative ions were detected the presence of C2H2 in the HMDSO-Ar discharge supports the hypothesis of a dust growth mechanism based on negative ions being trapped in the plasma. It was found that at the beginning of each cycle of dust formation during α -γ' transition, the discharge sustaining process is accompanied by a strong consumption of the HMDSO main by-products: HMDSO-15, CH4 and C2H2. At the end of the cycle, corresponding to the progressive disappearance of dust, the discharge switches back to its initial conditions. The beginning of the inverse transition, i.e. γ'-α , is most likely correlated to the growing void in the dust cloud and dust disappearance. In presence of dust nanoparticles, Ar+ and ArH+ dominate the ion population and consequently the discharge maintenance. When the dust particles gradually disappear, the discharge is rather controlled by Si2O(CH3)5+ ions. Moreover, the increased amount of such heavy ions reveals clearly their important income in the dust repelling process due to the drag force on the large sized dust even at short time scale during the injection time of HMDSO. Atomic-H production increases during the transition from dusty plasma to HMDSO-rich plasma with no dust and its role is associated to a delay in the dust nucleation stage.

  14. Theoretical studies on kinetics, mechanism and thermochemistry of gas-phase reactions of HFE-449mec-f with OH radicals and Cl atom.

    PubMed

    Deka, Ramesh Chandra; Mishra, Bhupesh Kumar

    2014-09-01

    A theoretical study on the mechanism and kinetics of the gas phase reactions of CF3CHFCF2OCH2CF3 (HFE-449mec-f) with the OH radicals and Cl atom have been performed using meta-hybrid modern density functional M06-2X using 6-31+G(d,p) basis set. Two conformers have been identified for CF3CHFCF2OCH2CF3 and the most stable one is considered for detailed study. Reaction profiles for OH-initiated hydrogen abstraction are modeled including the formation of pre-reactive and post-reactive complexes at entrance and exit channels. Our calculations reveal that hydrogen abstraction from the CH2 group is thermodynamically and kinetically more facile than that from the CHF group. Using group-balanced isodesmic reactions, the standard enthalpies of formation for HFE-449mecf and radicals generated by hydrogen abstraction, are also reported. The calculated bond dissociation energies for CH bonds are in good agreement with experimental results. The rate constants of the two reactions are determined for the first time in a wide temperature range of 250-450K. The calculated rate constant values are found to be 9.10×10(-15) and 4.77×10(-17)cm(3)molecule(-1)s(-1) for reactions with OH radicals and Cl atom, respectively. At 298K, the total calculated rate coefficient for reactions with OH radical is in good agreement with the experimental results. The atmospheric life time of HFE-449mec-f is estimated to be 0.287 years.

  15. Effect of base sequence on the DNA cross-linking properties of pyrrolobenzodiazepine (PBD) dimers.

    PubMed

    Rahman, Khondaker M; James, Colin H; Thurston, David E

    2011-07-01

    Pyrrolo[2,1-c][1,4]benzodiazepine (PBD) dimers are synthetic sequence-selective DNA minor-groove cross-linking agents that possess two electrophilic imine moieties (or their equivalent) capable of forming covalent aminal linkages with guanine C2-NH(2) functionalities. The PBD dimer SJG-136, which has a C8-O-(CH(2))(3)-O-C8'' central linker joining the two PBD moieties, is currently undergoing phase II clinical trials and current research is focused on developing analogues of SJG-136 with different linker lengths and substitution patterns. Using a reversed-phase ion pair HPLC/MS method to evaluate interaction with oligonucleotides of varying length and sequence, we recently reported (JACS, 2009, 131, 13 756) that SJG-136 can form three different types of adducts: inter- and intrastrand cross-linked adducts, and mono-alkylated adducts. These studies have now been extended to include PBD dimers with a longer central linker (C8-O-(CH(2))(5)-O-C8'), demonstrating that the type and distribution of adducts appear to depend on (i) the length of the C8/C8'-linker connecting the two PBD units, (ii) the positioning of the two reactive guanine bases on the same or opposite strands, and (iii) their separation (i.e. the number of base pairs, usually ATs, between them). Based on these data, a set of rules are emerging that can be used to predict the DNA-interaction behaviour of a PBD dimer of particular C8-C8' linker length towards a given DNA sequence. These observations suggest that it may be possible to design PBD dimers to target specific DNA sequences.

  16. Evaluation of multistep derivatization methods for identification and quantification of oxygenated species in organic aerosol.

    PubMed

    Flores, Rosa M; Doskey, Paul V

    2015-10-30

    Two, 3-step methods for derivatizing mono- and multi-functional species with carbonyl (CO), carboxylic acid (-COOH), and alcohol (-OH) moieties were compared and optimized. In Method 1, the CO, -COOH, and -OH moieties were converted (1) to methyloximes (R-CN-OCH3) with O-methylhydroxylamine hydrochloride (MHA), (2) to methyl esters (OC-R-OCH3) with (trimethylsilyl)diazomethane in methanol (TMSD/MeOH), and (3) to trimethylsilyl ethers [R-OSi(CH3)3] with N,O-bis(trimethylsilyl)-trifluoroacetamide (BSTFA) containing 1% trimethylchlorosilane (TMCS), respectively. Steps 1 and 3 of both methods were identical; however, in Step 2 of Method 2, -COOH moieties were derivatized with 10% (v/v) boron trifluoride (BF3) in MeOH or n-butanol (n-BuOH). The BF3/MeOH and BF3/n-BuOH were ineffective at converting species with more than 2-OH moieties. Average standard deviations for derivatization of 36 model compounds by the 3-step methods using TMSD/MeOH and BF3/(MeOH) were 7.4 and 14.8%, respectively. Average derivatization efficiencies for Methods 1 and 2 were 88.0 and 114%, respectively. Despite the lower average derivatization efficiency of Method 1, distinct advantages included a greater certainty of derivatization yield for the entire suite of mono- and multi-functional species and fewer processing steps for sequential derivatization. Detection limits for Method 1 using GC×GC-ToF-MS were 0.3-54pgm(-3). Approximately 100 oxygenated organic species were identified and quantified in aerosol filtered from 39m(3) of air in an urban location. Levels of species were 0.013-17ngm(-3) and were nearly all above the Method 1 limit of detection.

  17. Oral transmission of Chagas disease: typing of Trypanosoma cruzi from five outbreaks occurred in Venezuela shows multiclonal and common infections in patients, vectors and reservoirs.

    PubMed

    Muñoz-Calderón, A; Díaz-Bello, Z; Valladares, B; Noya, O; López, M C; Alarcón de Noya, B; Thomas, M C

    2013-07-01

    In Venezuela six episodes of oral transmission of Chagas disease (OChD) have been described, being the one reported in 2007 with a total of 103 people infected the largest worldwide. This work shows the use of three molecular markers (mini-exon gene and domains 24Sα and 18S of the ribosomal RNA) to characterize the infecting Trypanosoma cruzi strain of patients, reservoirs and vectors involved in five of the six OChD outbreaks. For this, 28 T. cruzi isolates were characterized by PCR, and the products of these reactions cloned and sequenced to reveal the existence of different TcI SL-IR genotypes. We also describe a new PCR assay able to discriminate between TcIb and TcId parasite populations. In summary, we have identified mostly parasites with the TcId haplotype and multiclonal populations with predominance of haplotype TcId (65.2%). Additionally, populations of haplotypes TcIb, TcIa and mixtures (TcId+TcIb, TcId+TcIa, TcIb+TcIa) are recurrent in samples obtained from children. The analysis of the SL-IR motif showed two clones depicting a different motif that could be an evidence for a possible hybrid haplotype between TcIa and TcIb (haplotype TcIa/Ib). Interestingly, in a single patient haplotype differences between T.cruzi isolates obtained pre and post-treatment were found. In conclusion, our findings show that in order to understand the pathogenic mechanisms involved in the orally acquired Chagas disease there is a need to join efforts to study T. cruzi haplotypes, their tissue tropisms and their susceptibility to chemoteraphy.

  18. Structural changes of humic acids from sinking organic matter and surface sediments investigated by advanced solid-state NMR: Insights into sources, preservation and molecularly uncharacterized components

    NASA Astrophysics Data System (ADS)

    Mao, Jingdong; Tremblay, Luc; Gagné, Jean-Pierre

    2011-12-01

    Knowledge of the structural changes that particulate organic matter (POM) undergoes in natural systems is essential for determining its reactivity and fate. In the present study, we used advanced solid-state NMR techniques to investigate the chemical structures of sinking particulate matter collected at different depths as well as humic acids (HAs) extracted from these samples and underlying sediments from the Saguenay Fjord and the St. Lawrence Lower Estuary (Canada). Compared to bulk POM, HAs contain more non-polar alkyls, aromatics, and aromatic C-O, but less carbohydrates (or carbohydrate-like structures). In the two locations studied, the C and N contents of the samples (POM and HAs) decreased with depth and after deposition onto sediments, leaving N-poor but O-enriched HAs and suggesting the involvement of partial oxidation reactions during POM microbial degradation. Advanced NMR techniques revealed that, compared to the water-column HAs, sedimentary HAs contained more protonated aromatics, non-protonated aromatics, aromatic C-O, carbohydrates (excluding anomerics), anomerics, OC q, O-C q-O, OCH, and OCH 3 groups, but less non-polar alkyls, NCH, and mobile CH 2 groups. These results are consistent with the relatively high reactivity of lipids and proteins or peptides. In contrast, carbohydrate-like structures were selectively preserved and appeared to be involved in substitution and copolymerization reactions. Some of these trends support the selective degradation (or selective preservation) theory. The results provide insights into mechanisms that likely contribute to the preservation of POM and the formation of molecules that escape characterization by traditional methods. Despite the depletion of non-polar alkyls with depth in HAs, a significant portion of their general structure survived and can be assigned to a model phospholipid. In addition, little changes in the connectivities of different functional groups were observed. Substituted and copolymerized

  19. Conformational analysis and vibrational spectroscopic studies of tetraethoxysilane and its hydrolysis products: A DFT prediction

    NASA Astrophysics Data System (ADS)

    Machado, E. S.; Silva, D. A.; de Almeida, K. J.; Felicíssimo, V. C.

    2017-04-01

    The density functional theory was used to carry out a systematic investigation about the conformational and vibrational analyses of tetraethoxysilane (TEOS) and its hydrolysis products (Si(OCH2CH3)4-n(OH)n, n = 1-4). All possible potential energy curve (PEC) scans were performed in different symmetry point groups, D2d, S4, C2v and Cs, for the fully hydrolyzed product of TEOS, Si(OH)4. The main results indicate clear differences in the spectral profile of each molecular system, which can be used for monitoring the sol-gel processes at the hydrolysis stage. The most significative changes take place in 750-1000 cm-1, where mainly the νas SiO asymmetric stretching and δSiOH angular deformation modes are localized. A significant coupling between νas SiO and δSiOH is observed for the computed spectra of Si(OH)4 in gas-phase, with more pronounced effect for S4 ad D2d symmetries. For the partial hydrolysis products of TEOS (Si(OCH2CH3)4-n(OH)n, n = 1-3) this coupling is also present and it is evidenced by the fact that both vibrational bands in 750-900 cm-1 (δSiOH) and 900-1000 cm-1 (νSiO) show a great contribution of the SiO bond length displacements as much as of the SiOH bond angle changes.

  20. Comparison of collision velocity differences of drops and graupel particles in a very turbulent cloud

    NASA Astrophysics Data System (ADS)

    Pinsky, M.; Khain, A.; Rosenfeld, D.; Pokrovsky, A.

    The motion of water drops and graupel particles within a turbulent medium is analyzed. The turbulence is assumed to be homogeneous and isotropic. It is demonstrated that the inertia of drops and graupel particles falling within a turbulent flow leads to the formation of significant velocity deviations from the surrounding air, as well as to the formation of substantial relative velocity between drops and graupel particles. The results of calculations of the continuous growth of raindrops and graupel particles moving within a cloud of small droplets are presented both in a non-turbulent medium and within turbulent flows of different turbulence intensity. Continuous growth of a drop-collector was calculated with the coalescence efficiency E ɛ=1, as well as using E ɛ values provided by Beard and Ochs [Beard, K.V., Ochs, H.T., 1984. Collection and coalescence efficiencies for accretion. J. Geophys. Res., 89: 7165-7169.] ranging from 0.5 to about 0.75 for different droplet sizes. In the case of graupel-droplet interaction E ɛ was assumed equal to 1. It is shown that in the case E ɛ=1 in a non-turbulent medium, the growth rates of graupel and raindrops are close. Under turbulent conditions typical of mature convective clouds, graupel grows much faster than a raindrop. In the case E ɛ<1 the growth rate of a water drop slows down significantly, so that graupel grows faster than raindrops even under non-turbulent conditions. Turbulence greatly increases the difference between the growth rates of graupel and drop-collectors. Possible consequences of the faster growth of graupel in terms of cloud microphysics are discussed.

  1. Characteristics and degradation of carbon and phosphorus from aquatic macrophytes in lakes: Insights from solid-state (13)C NMR and solution (31)P NMR spectroscopy.

    PubMed

    Liu, Shasha; Zhu, Yuanrong; Meng, Wei; He, Zhongqi; Feng, Weiying; Zhang, Chen; Giesy, John P

    2016-02-01

    Water extractable organic matter (WEOM) derived from macrophytes plays an important role in biogeochemical cycling of nutrients, including carbon (C), nitrogen (N) and phosphorus (P) in lakes. However, reports of their composition and degradation in natural waters are scarce. Therefore, compositions and degradation of WEOM derived from six aquatic macrophytes species of Tai Lake, China, were investigated by use of solid-state (13)C NMR and solution (31)P NMR spectroscopy. Carbohydrates were the predominant constituents of WEOM fractions, followed by carboxylic acid. Orthophosphate (ortho-P) was the dominant form of P (78.7% of total dissolved P) in the water extracts, followed by monoester P (mono-P) (20.6%) and little diester P (0.65%). The proportion of mono-P in total P species increased with the percentage of O-alkyl and O-C-O increasing in the WEOM, which is likely due to degradation and dissolution of biological membranes and RNA from aquatic plants. Whereas the proportion of mono-P decreased with alkyl-C, NCH/OCH3 and COO/N-C=O increasing, which may be owing to the insoluble compounds including C functional groups of alkyl-C, NCH/OCH3 and COO/N-C=O, such as aliphatic biopolymers, lignin and peptides. Based on the results of this study and information in the literature about water column and sediment, we propose that WEOM, dominated by polysaccharides, are the most labile and bioavailable component in debris of macrophytes. Additionally, these WEOMs would also be a potential source for bioavailable organic P (e.g., RNA, DNA and phytate) for lakes.

  2. Lewis Acid and Substituent Effects on the Molecular Mechanism for the Nazarov Reaction of Penta-1,4-dien-3-one and Derivatives. A Topological Analysis Based on the Combined Use of Electron Localization Function and Catastrophe Theory.

    PubMed

    Polo, Victor; Andrés, Juan

    2007-05-01

    The joint use of the topological analysis provided by the electron localization function (ELF) and catastrophe theory (CT), at the B3LYP/6-31G(d) calculation level, allows us to examine the Lewis acid (protonation H(+) and presence of BH3) and the role of an electron donor substituent (-OCH3) at α and β positions along the course of the molecular mechanism for the Nazarov rearrangement of penta-1,4-dien-3-one and eight derivatives. The progress of the reaction is monitored by the changes of the ELF structural stability domains (SSDs), each change being controlled by a turning point derived from CT. These SSDs and the corresponding turning points are associated with a sequence of elementary chemical steps. Along the cyclization path of penta-1,4-diene-3-one, four SSDs as well as three turning points (cusp1-fold1-cusp2) have been characterized. The first and second SSDs correspond to a polarization of the C-O bond and electronic redistribution among the C-C bonds, respectively, and they can be associated with the formation of an oxyallyl structure. The third and fourth SSDs can be assigned to the ring closure process. Protonation of the oxygen atom shifts the reactive directly into the second SSD, greatly reducing the activation and reaction energies. The electronic effects due to Lewis acids and electron donor substituents have been rationalized in terms of calculations of mesomeric structures from ELF basin populations. The combination of Lewis acids together with α and β -OCH3 substitutions renders a cooperative and competitive effect on activation and reaction free energies, respectively.

  3. A thermodynamic model for calculating methane solubility, density and gas phase composition of methane-bearing aqueous fluids from 273 to 523 K and from 1 to 2000 bar

    NASA Astrophysics Data System (ADS)

    Duan, Zhenhao; Mao, Shide

    2006-07-01

    A thermodynamic model is presented to calculate methane solubility, liquid phase density and gas phase composition of the H 2O-CH 4 and H 2O-CH 4-NaCl systems from 273 to 523 K (possibly up to 573 K), from 1 to 2000 bar and from 0 to 6 mol kg -1 of NaCl with experimental accuracy. By a more strict theoretical approach and using updated experimental data, this model made substantial improvements over previous models: (1) the accuracy of methane solubility in pure water in the temperature range between 273 and 283 K is increased from about 10% to about 5%, but confirms the accuracy of the Duan model [Duan Z., Moller N., Weare J.H., 1992a. Prediction of methane solubilities in natural waters to high ionic strength from 0 to 250 °C and from 0 to 1600 bar. Geochim. Cosmochim. Acta56, 1451-1460] above 283 K up to 2000 bar; (2) the accuracy of methane solubility in the NaCl aqueous solutions is increased from >12% to about 6% on average from 273 K and 1 bar to 523 K and 2000 bar; (3) this model is able to calculate water content in the gas phase and liquid phase density, which cannot be calculated by previous models; and (4) it covers a wider range of temperature and pressure space. With a simple approach, this model is extended to predict CH 4 solubility in other aqueous salt solutions containing Na +, K +, Mg 2+, Ca 2+, Cl - and SO42-, such as seawater and geothermal brines, with excellent accuracy. This model is also able to calculate homogenization pressure of fluid inclusions (CH 4-H 2O-NaCl) and CH 4 solubility in water at gas-liquid-hydrate phase equilibrium. A computer code is developed for this model and can be downloaded from the website: www.geochem-model.org/programs.htm.

  4. Nanomapping of CD1d-glycolipid complexes on THP1 cells by using simultaneous topography and recognition imaging.

    PubMed

    Duman, Memed; Chtcheglova, Lilia A; Zhu, Rong; Bozna, Bianca L; Polzella, Paolo; Cerundolo, Vicenzo; Hinterdorfer, Peter

    2013-09-01

    CD1d molecule, a monomorphic major histocompatibility complex class I-like molecule, presents different types of glycolipids to invariant natural killer T (iNKT) cells that play an important role in immunity to infection and tumors, as well as in regulating autoimmunity. Here, we present simultaneous topography and recognition imaging (TREC) analysis to detect density, distribution and localization of single CD1d molecules on THP1 cells that were loaded with different glycolipids. TREC was conducted using magnetically coated atomic force microscopy tips functionalized with a biotinylated iNKT cell receptor (TCR). The recognition map revealed binding sites visible as dark spots, resulting from oscillation amplitude reduction during specific binding between iNKT TCR and the CD1d-glycolipid complex. THP1 cells were pulsed with three different glycolipids (α-GalCer, C20 and OCH12) for 4 and 16 hr. Whereas CD1d-α-GalCer and CD1d-C20:2 complexes on cellular membrane formed smaller microdomains up to ~10 000 nm(2) (dimension area), OCH12 loaded CD1d complexes presented larger clusters with a dimension up to ~30 000 nm(2). Moreover, the smallest size of recognition spots was about 25 nm, corresponding to a single CD1d binding site. TREC successfully revealed the distribution and localization of CD1d-glycolipid complexes on THP1 cell with single molecule resolution under physiological conditions.

  5. Thermal decomposition mechanisms of the methoxyphenols: formation of phenol, cyclopentadienone, vinylacetylene, and acetylene.

    PubMed

    Scheer, Adam M; Mukarakate, Calvin; Robichaud, David J; Nimlos, Mark R; Ellison, G Barney

    2011-11-24

    The pyrolyses of the guaiacols or methoxyphenols (o-, m-, and p-HOC(6)H(4)OCH(3)) have been studied using a heated SiC microtubular (μ-tubular) reactor. The decomposition products are detected by both photoionization time-of-flight mass spectroscopy (PIMS) and matrix isolation infrared spectroscopy (IR). Gas exiting the heated SiC μ-tubular reactor is subject to a free expansion after a residence time of approximately 50-100 μs. The PIMS reveals that, for all three guaiacols, the initial decomposition step is loss of methyl radical: HOC(6)H(4)OCH(3) → HOC(6)H(4)O + CH(3). Decarbonylation of the HOC(6)H(4)O radical produces the hydroxycyclopentadienyl radical, C(5)H(4)OH. As the temperature of the μ-tubular reactor is raised to 1275 K, the C(5)H(4)OH radical loses a H atom to produce cyclopentadienone, C(5)H(4)═O. Loss of CO from cyclopentadienone leads to the final products, acetylene and vinylacetylene: C(5)H(4)═O → [CO + 2 HC≡CH] or [CO + HC≡C-CH═CH(2)]. The formation of C(5)H(4)═O, HCCH, and CH(2)CHCCH is confirmed with IR spectroscopy. In separate studies of the (1 + 1) resonance-enhanced multiphoton ionization (REMPI) spectra, we observe the presence of C(6)H(5)OH in the molecular beam: C(6)H(5)OH + λ(275.1 nm) → [C(6)H(5)OH Ã] + λ(275.1nm) → C(6)H(5)OH(+). From the REMPI and PIMS signals and previous work on methoxybenzene, we suggest that phenol results from a radical/radical reaction: CH(3) + C(5)H(4)OH → [CH(3)-C(5)H(4)OH]* → C(6)H(5)OH + 2H.

  6. Synthesis and biological evaluation of flavones and benzoflavones as inhibitors of BCRP/ABCG2.

    PubMed

    Juvale, Kapil; Stefan, Katja; Wiese, Michael

    2013-09-01

    Multidrug resistance (MDR) often leads to a failure of cancer chemotherapy. Breast Cancer Resistance Protein (BCRP/ABCG2), a member of the superfamily of ATP binding cassette proteins has been found to confer MDR in cancer cells by transporting molecules with amphiphilic character out of the cells using energy from ATP hydrolysis. Inhibiting BCRP can be a solution to overcome MDR. We synthesized a series of flavones, 7,8-benzoflavones and 5,6-benzoflavones with varying substituents at positions 3, 3' and 4' of the (benzo)flavone structure. All synthesized compounds were tested for BCRP inhibition in Hoechst 33342 and pheophorbide A accumulation assays using MDCK cells expressing BCRP. All the compounds were further screened for their P-glycoprotein (P-gp) and Multidrug resistance-associated protein 1 (MRP1) inhibitory activity by calcein AM accumulation assay to check the selectivity towards BCRP. In addition most active compounds were investigated for their cytotoxicity. It was observed that in most cases 7,8-benzoflavones are more potent in comparison to the 5,6-benzoflavones. In general it was found that presence of a 3-OCH3 substituent leads to increase in activity in comparison to presence of OH or no substitution at position 3. Also, it was found that presence of 3',4'-OCH3 on phenyl ring lead to increase in activity as compared to other substituents. Compound 24, a 7,8-benzoflavone derivative was found to be most potent being 50 times selective for BCRP and showing very low cytotoxicity at higher concentrations.

  7. Reduced CSF turnover and decreased ventricular Aβ42 levels are related

    PubMed Central

    2011-01-01

    Background The appearance of Aβ42 peptide deposits is admitted to be a key event in the pathogenesis of Alzheimer's disease, although amyloid deposits also occur in aged non-demented subjects. Aβ42 is a degradation product of the amyloid protein precursor (APP). It can be catabolized by several enzymes, reabsorbed by capillaries or cleared into cerebrospinal fluid (CSF). The possible involvement of a decrease in CSF turnover in A4β2 deposit formation is up to now poorly known. We therefore investigated a possible relationship between a reduced CSF turnover and the CSF levels of the A4β2 peptide. To this aim, CSF of 31 patients with decreased CSF turnover were studied. These patients presented chronic hydrocephalus communicating or obstructive, which required surgery (ventriculostomy or ventriculo-peritoneal shunt). Nine subjects had idiopathic normal pressure hydrocephalus (iNPH), and the other 22 chronic hydrocephalus from other origins (oCH). The Aβ42 peptide concentration was measured by an ELISA test in 31 ventricular CSF samples and in 5 lumbar CSF samples from patients with communicating hydrocephalus. Results The 5 patients with lumbar CSF analysis had similar levels of lumbar and ventricular Aβ42. A significant reduction in Aβ42 ventricular levels was observed in 24 / 31 patients with hydrocephalus. The values were lower than 300 pg/ml in 5 out of 9 subjects with iNPH, and in 15 out of 22 subjects with oCH. Conclusion The decrease of CSF Aβ42 seems to occur independently of the surgical hydrocephalus aetiology. This suggests that a CSF reduced turnover may play an important role in the decrease of CSF Aβ42 concentration. PMID:21569454

  8. Occurrence and fate of organochlorinated pesticides and PAH in agricultural soils from the Ebro River basin.

    PubMed

    Hildebrandt, Alain; Lacorte, Sílvia; Barceló, Damià

    2009-08-01

    This study was aimed to assess the presence and fate of 22 organochlorinated pesticides (OCHs) and their degradation products and 16 Environmental Protection Agency-priority polycyclic aromatic hydrocarbons (PAHs) in soils of the Ebro River basin (NE Spain) during a 3-year period. The study site is characterized by a long and active agricultural history where pesticides have largely been used. Soils were extracted using pressurized liquid extraction followed by gas chromatography-mass spectrometry. This procedure was optimized in terms of multiresidue analysis and effective cleanup and proved to have excellent analytical performance (recoveries ranging between 71% and 133%, standard deviation <14%, and a method detection limit from 0.19 to 7.38 microg/kg). Soils form the Ebro basin showed a prevalence of 4,4'-DDT and 4,4'-DDE, found in 53% and 88% of the soil samples between 0.13 and 58.17 microg/kg-dw (dry weight), respectively, indicating a slight decreasing trend of DDT within time. PAHs were detected in all soil samples at concentrations up to 465 microg/kg-dw, and the phenanthrene/anthracene (<10) and fluoranthene/pyrene (>1) ratios indicated combustion processes as the main source attributing to the burning of weeds and vegetable wastes after harvesting. No traces of any of the OCHs and PAHs were detected in groundwater, indicating that leaching for agricultural fields is not an important process of transport for these compounds. Overall, we propose the need to perform a monitoring program to evaluate the temporal tendencies and potential impact of pesticides and PAH in soils.

  9. Functional disubstituted polyacetylenes: Synthesis, liquid crystallinity, light emission, and fluorescent photopatterning of biphenyl-containing poly(1-phenyl-octyne)s with different functional bridges.

    PubMed

    Lam, Jacky W Y; Qin, Anjun; Dong, Yuping; Lai, Lo Ming; Häussler, Matthias; Dong, Yongqiang; Tang, Ben Zhong

    2006-11-02

    Biphenyl (Biph)-containing 1-phenyl-1-octynes and their polymers are synthesized, and the effects of functional bridge groups on the mesomorphic and optical properties of the polymers are studied. The nonmesomorphic disubstituted acetylene monomers (C6H13)C[triple bond]C(C6H4)O(CH2)12O-Biph-OC7H15 (1), (C6H13)C[triple bond]C(C6H4)O(CH2)11OOC-Biph-OC7H15 (2), and (C6H13)C[triple bond]C(C6H4)CO2(CH2)12OOC-Biph-OC7H15 (3) are prepared by multistep reaction routes and converted into their corresponding polymers P1-P3 by a WCl6-Ph4Sn catalyst. The structures and properties of the polymers are characterized and evaluated by NMR, TGA, DSC, POM, XRD, UV, and PL analyses. The mesogenic pendants have endowed the polymers with high thermal stability (> or =400 degrees C). While P1 exhibits no liquid crystallinity, P2 and P3 form enantiotropic S(A) phase with a monolayer structure. Upon photoexcitation, the polymers emit blue and blue-green lights of 460 and 480 nm, respectively, in THF with quantum efficiencies larger than 30%. UV irradiation of a thin film of P2 through a mask oxidizes and quenches the light emission of the exposed regions, generating a two-dimensional luminescent photoimage.

  10. Hydrogen production from the steam reforming of Dinethyl Ether and Methanol

    SciTech Connect

    Semelsberger, T. A.; Borup, R. L.

    2004-01-01

    This study investigates dimethyl ether (DME) steam reforming for the generation of hydrogen rich fuel cell feeds for fuel cell applications. Methanol has long been considered as a fuel for the generation of hydrogen rich fuel cell feeds due to its high energy density, low reforming temperature, and zero impurity content. However, it has not been accepted as the fuel of choice due its current limited availability, toxicity and corrosiveness. While methanol steam reforming for the generation of hydrogen rich fuel cell feeds has been extensively studied, the steam reforming of DME, CH{sub 3}OCH{sub 3} + 3H{sub 2}O = 2CO{sub 2} + 6H{sub 2}, has had limited research effort. DME is the simplest ether (CH{sub 3}OCH{sub 3}) and is a gas at ambient conditions. DME has physical properties similar to those of LPG fuels (i.e. propane and butane), resulting in similar storage and handling considerations. DME is currently used as an aerosol propellant and has been considercd as a diesel substitute due to the reduced NOx, SOx and particulate emissions. DME is also being considered as a substitute for LPG fuels, which is used extensively in Asia as a fuel for heating and cooking, and naptha, which is used for power generation. The potential advantages of both methanol and DME include low reforming temperature, decreased fuel proccssor startup energy, environmentally benign, visible flame, high heating value, and ease of storage and transportation. In addition, DME has the added advantages of low toxicity and being non-corrosive. Consequently, DME may be an ideal candidate for the generation of hydrogen rich fuel cell feeds for both automotive and portable power applications. The steam reforming of DME has been demonstrated to occur through a pair of reactions in series, where the first reaction is DME hydration followed by MeOH steam reforming to produce a hydrogen rich stream.

  11. Site reactivity in the free radicals induced damage to leucine residues: a theoretical study.

    PubMed

    Medina, M E; Galano, A; Alvarez-Idaboy, J R

    2015-02-21

    Several recent computational studies have tried to explain the observed selectivity in radical damage to proteins. In this work we use Density Functional Theory and Transition State Theory including tunnelling corrections, reaction path degeneracy, the effect of diffusion, and the role of free radicals to get further insights into this important topic. The reaction between a leucine derivative and free radicals of biological significance, in aqueous and lipid media, has been investigated. Both thermochemical and kinetic analyses, in both hydrophilic and hydrophobic environments, have been carried out. DPPH, ˙OOH, ˙OOCH3, ˙OOCH2Cl, ˙OOCHCl2 and ˙OOCHCH2 radicals do not react with the target molecule. The reactions are proposed to be kinetically controlled. The leucine gamma site was the most reactive for the reactions with ˙N3, ˙OOCCl3, ˙OCH3, ˙OCH2Cl, and ˙OCHCl2 radicals, with rate constants equal to 1.97 × 10(5), 3.24 × 10(4), 6.68 × 10(5), 5.98 × 10(6) and 8.87 × 10(8) M(-1) s(-1), respectively, in aqueous solution. The ˙Cl, ˙OH and ˙OCCl3 radicals react with leucine at the beta, gamma, and delta positions at rates close to the diffusion limit with the alpha position which is the slowest path and the most thermodynamically favored. The presented results confirm that the Bell-Evans-Polanyi principle does not apply for the reactions between amino acid residues and free radicals. Regarding the influence of the environment on the reactivity of the studied series of free radicals towards leucine residues, it is concluded that hydrophilic media slightly lower the reactivity of the studied radicals, compared to hydrophobic ones, albeit the trends in reactivity are very similar.

  12. Thrombin/Matrix Metalloproteinase-9-Dependent SK-N-SH Cell Migration is Mediated Through a PLC/PKC/MAPKs/NF-κB Cascade.

    PubMed

    Yang, Chien-Chung; Lin, Chih-Chung; Chien, Peter Tzu-Yu; Hsiao, Li-Der; Yang, Chuen-Mao

    2016-11-01

    Thrombin has been known to activate inflammatory genes including matrix metalloproteinases (MMPs). The elevated expression of MMP-9 has been observed in patients with neuroinflammatory diseases and may contribute to the pathology of brain diseases. However, the mechanisms underlying thrombin-induced MMP-9 expression in SK-N-SH cells remain unknown. The effects of thrombin on MMP-9 expression were examined in SK-N-SH cells by gelatin zymography, Western blot, real-time PCR, promoter activity assay, and cell migration assay. The detailed mechanisms were analyzed by using pharmacological inhibitors and small intefering RNA (siRNA) transfection. Here, we demonstrated that thrombin induced the expression of proform MMP-9 and migration of SK-N-SH cells, which were attenuated by pretreatment with the inhibitor of thrombin (PPACK), Gq (GPA2A), PC-PLC (D609), PI-PLC (ET-18-OCH3), nonselective protien kinase C (PKC, GF109203X), PKCα/βII (Gö6983), PKCδ (Rottlerin), p38 mitogen-activated protein kinases (MAPK) (SB202190), JNK1/2 (SP600125), or NF-κB (Bay11-7082 or Helenalin) and transfection with siRNA of Gq, PKCα, PKCβ, PKCδ, p38, JNK1/2, IKKα, IKKβ, or p65. Moreover, thrombin-stimulated PKCα/βII, PKCδ, p38 MAPK, JNK1/2, or p65 phosphorylation was abrogated by their respective inhibitor of PPACK, GPA2A, D609, ET-18-OCH3, Gö6983, Rottlerin, SB202190, SP600125, Bay11-7082, or Helenalin. Pretreatment with these inhibitors or transfection with MMP-9 siRNA also blocked thrombin-induced SK-N-SH cell migration. Our results show that thrombin stimulates a Gq/PLC/PKCs/p38 MAPK and JNK1/2 cascade, which in turn triggers NF-κB activation and ultimately induces MMP-9 expression and cell migration in SK-N-SH cells.

  13. Impact of water on the cis-trans photoisomerization of hydroxychalcones.

    PubMed

    Leydet, Yoann; Batat, Pinar; Jonusauskas, Gediminas; Denisov, Sergey; Lima, João Carlos; Parola, A Jorge; McClenaghan, Nathan D; Pina, Fernando

    2013-05-23

    The photochromism of a 2-hydroxychalcone has been studied in CH3CN and H2O/CH3OH (1/1, v/v), as well as in analogous deuterated solvents using steady-state (UV-vis absorption, (1)H and (13)C NMR) and time-resolved (ultrafast transient absorption and nanosecond flow flash photolysis) spectroscopies. Whereas the irradiation of trans-chalcone (Ct) under neutral pH conditions leads to the formation of the same final chromene derivative (B) in both media, two distinct photochemical mechanisms are proposed in agreement with thermodynamic and kinetic properties of the chemical reaction network at the ground state. Following light excitation, the first steps are identical in acetonitrile and aqueous solution: the Franck-Condon excited state rapidly populates the trans-chalcone singlet excited state (1)Ct* (LE), which evolves into a twisted state (1)P*. This excited state is directly responsible for the photochemistry in acetonitrile in the nanosecond time scale (16 ns) leading to the formation of cis-chalcone (Cc) through a simple isomerization process. The resulting cis-chalcone evolves into the chromene B through a tautomerization process in the ground state (τ = 10 ms). Unlike in acetonitrile, in H2O/CH3OH (1/1, v/v), the P* state becomes unstable and evolves into a new state attributed to the tautomer (1)Q*. This state directly evolves into B in one photochemical step through a consecutive ultrafast tautomerization process followed by electrocyclization. This last case represents a new hypothesis in the photochromism of 2-hydroxychalcone derivatives.

  14. Complex Organic Molecules tracing shocks along the outflow cavity in the high-mass protostar IRAS 20126+4104

    NASA Astrophysics Data System (ADS)

    Palau, Aina; Walsh, Catherine; Sánchez-Monge, Álvaro; Girart, Josep M.; Cesaroni, Riccardo; Jiménez-Serra, Izaskun; Fuente, Asunción; Zapata, Luis A.; Neri, Roberto

    2017-01-01

    We report on subarcsecond observations of complex organic molecules (COMs) in the high-mass protostar IRAS 20126+4104 with the Plateau de Bure Interferometer in its most extended configurations. In addition to the simple molecules SO, HNCO and H_2^{13}CO, we detect emission from CH3CN, CH3OH, HCOOH, HCOOCH3, CH3OCH3, CH3CH2CN, CH3COCH3, NH2CN, and (CH2OH)2. SO and HNCO present a X-shaped morphology consistent with tracing the outflow cavity walls. Most of the COMs have their peak emission at the putative position of the protostar, but also show an extension towards the south(east), coinciding with an H2 knot from the jet at about 800-1000 au from the protostar. This is especially clear in the case of H_2^{13}CO and CH3OCH3. We fitted the spectra at representative positions for the disc and the outflow, and found that the abundances of most COMs are comparable at both positions, suggesting that COMs are enhanced in shocks as a result of the passage of the outflow. By coupling a parametric shock model to a large gas-grain chemical network including COMs, we find that the observed COMs should survive in the gas phase for ˜2000 yr, comparable to the shock lifetime estimated from the water masers at the outflow position. Overall, our data indicate that COMs in IRAS 20126+4104 may arise not only from the disc, but also from dense and hot regions associated with the outflow.

  15. Chromium removal from electroplating wastewater by coir pith.

    PubMed

    Suksabye, Parinda; Thiravetyan, Paitip; Nakbanpote, Woranan; Chayabutra, Supanee

    2007-03-22

    Coir pith is a by-product from padding used in mattress factories. It contains a high amount of lignin. Therefore, this study investigated the use of coir pith in the removal of hexavalent chromium from electroplating wastewater by varying the parameters, such as the system pH, contact time, adsorbent dosage, and temperature. The maximum removal (99.99%) was obtained at 2% (w/v) dosage, particle size <75microm, at initial Cr(VI) 1647mgl(-1), system pH 2, and an equilibrium time of 18h. The adsorption isotherm of coir pith fitted reasonably well with the Langmuir model. The maximum Cr(VI) adsorption capacity of coir pith at 15, 30, 45 and 60 degrees C was 138.04, 197.23, 262.89 and 317.65mgCr(VI)g(-1) coir pith, respectively. Thermodynamic parameters indicated an endothermic process and the adsorption process was favored at high temperature. Desorption studies of Cr(VI) on coir pith and X-ray absorption near edge structure (XANES) suggested that most of the chromium bound on the coir pith was in Cr(III) form due to the fact that the toxic Cr(VI) adsorbed on the coir pith by electrostatic attraction was easily reduced to less toxic Cr(III). Fourier transform infrared (FT-IR) spectrometry analysis indicated that the carbonyl (CO) groups and methoxy (O-CH(3)) groups from the lignin structure in coir pith may be involved in the mechanism of chromium adsorption. The reduced Cr(III) on the coir pith surface may be bound with CO groups and O-CH(3) groups through coordinate covalent bonding in which a lone pair of electrons in the oxygen atoms of the methoxy and carbonyl groups can be donated to form a shared bond with Cr(III).

  16. Photocatalytic degradation of bromothymol blue with Ruthenium(II) bipyridyl complex in aqueous basic solution

    NASA Astrophysics Data System (ADS)

    Fui, Mark Lee Wun; Hang, Ng Kim; Arifin, Khuzaimah; Minggu, Lorna Jeffery; Kassim, Mohammad Bin

    2016-11-01

    Ru(II) bipyridyl photocatalyst with the formula, [Ru(bpy)2(o-CH3-bzpypz)](PF6)2] (Ru01) and [Ru(bpy)2(o-Cl-bzpypz)](PF6)2] (Ru02), where bpy = 2,2'-bipyridyl, o-CH3-bzpypz = (3-(pyridin-2-yl)-1H-pyrazol-1-yl)(o-tolyl)methanone and o-Cl-bzpypz = (2-chlorophenyl)(3-(pyridin-2-yl)-1H-pyrazol-1-yl)methanone, has been successfully synthesized and characterized on the basis of C, H, N elemental analysis, IR, UV-Vis and NMR spectroscopy. Both Ru(II) complexes showed Infrared stretching frequencies at 1742-1736 cm-1 v(C=O), 1605 cm-1 v(C=N) and 842-837 cm-1 v(PF). Full geometry optimization of the complex structures were carried out using DFT method with B3LYP exchange-correlation functional and 6-31G (d,p) basis-set for H, C, N, O and Cl; and LAN2LDZ basis set as effective core potential for the ruthenium centre. The highest-occupied molecular orbital (HOMO) energy levels of Ru01 and Ru02 are -5.63 and -5.55 eV, respectively. The photocatalytic properties of the Ru(II) complexes were evaluated by studying the degradation of aqueous bromothymol blue (BTB) under light illumination. The mechanisms are presented and discussed to highlight the role of the ruthenium complex in the degradation process.

  17. Synthesis of formamide and isocyanic acid after ion irradiation of frozen gas mixtures

    NASA Astrophysics Data System (ADS)

    Kaňuchová, Z.; Urso, R. G.; Baratta, G. A.; Brucato, J. R.; Palumbo, M. E.; Strazzulla, G.

    2016-01-01

    Context. Formamide (NH2HCO) and isocyanic acid (HNCO) have been observed as gaseous species in several astronomical environments such as cometary comae and pre- and proto-stellar objects. A debate is open on the formation route of those molecules, in particular if they are formed by chemical reactions in the gas phase and/or on grains. In this latter case it is relevant to understand if the formation occurs through surface reactions or is induced by energetic processing. Aims: We present arguments that support the formation of formamide in the solid phase by cosmic-ion-induced energetic processing of ices present as mantles of interstellar grains and on comets. Formamides, along with other molecules, are expelled in the gas phase when the physical parameters are appropriate to induce the desorption of ices. Methods: We have performed several laboratory experiments in which ice mixtures (H2O:CH4:N2, H2O:CH4:NH3, and CH3OH:N2) were bombarded with energetic (30-200 keV) ions (H+ or He+). FTIR spectroscopy was performed before, during, and after ion bombardment. In particular, the formation of HNCO and NH2HCO was measured quantiatively. Results: Energetic processing of ice can quantitatively reproduce the amount of NH2HCO observed in cometary comae and in many circumstellar regions. HNCO is also formed, but additional formation mechanisms are requested to quantitatively account for the astronomical observations. Conclusions: We suggest that energetic processing of ices in the pre- and proto-stellar regions and in comets is the main mechanism to produce formamide, which, once it is released in the gas phase because of desorption of ices, is observed in the gas phase in these astrophysical environments.

  18. Low-energy (<20 eV) and high-energy (1000 eV) electron-induced methanol radiolysis of astrochemical interest

    NASA Astrophysics Data System (ADS)

    Sullivan, Kristal K.; Boamah, Mavis D.; Shulenberger, Katie E.; Chapman, Sitara; Atkinson, Karen E.; Boyer, Michael C.; Arumainayagam, Christopher R.

    2016-07-01

    We report the first infrared study of the low-energy (<20 eV) electron-induced reactions of condensed methanol. Our goal is to simulate processes which occur when high-energy cosmic rays interact with interstellar and cometary ices, where methanol, a precursor of several prebiotic species, is relatively abundant. The interactions of high-energy radiation, such as cosmic rays (Emax ˜ 1020 eV), with matter produce large numbers of low-energy secondary electrons, which are known to initiate radiolysis reactions in the condensed phase. Using temperature programmed desorption (TPD) and infrared reflection absorption spectroscopy (IRAS), we have investigated low-energy (5-20 eV) and high-energy (˜1000 eV) electron-induced reactions in condensed methanol (CH3OH). IRAS has the benefit that it does not require thermal processing prior to product detection. Using IRAS, we have found evidence for the formation of ethylene glycol (HOCH2CH2OH), formaldehyde (CH2O), dimethyl ether (CH3OCH3), methane (CH4), carbon dioxide (CO2), carbon monoxide (CO), and the hydroxyl methyl radical (·CH2OH) upon both low-energy and high-energy electron irradiation of condensed methanol at ˜85 K. Additionally, TPD results, presented herein, are similar for methanol films irradiated with both 1000 eV and 20 eV electrons. These IRAS and TPD findings are qualitatively consistent with the hypothesis that high-energy condensed phase radiolysis is mediated by low-energy electron-induced reactions. Moreover, methoxymethanol (CH3OCH2OH) could serve as a tracer molecule for electron-induced reactions in the interstellar medium. The results of experiments such as ours may provide a fundamental understanding of how complex organic molecules are synthesized in cosmic ices.

  19. Reaction chemistry and ligand exchange at cadmium-selenide nanocrystal surfaces.

    PubMed

    Owen, Jonathan S; Park, Jungwon; Trudeau, Paul-Emile; Alivisatos, A Paul

    2008-09-17

    The surface chemistry of cadmium selenide nanocrystals, prepared from tri-n-octylphosphine selenide and cadmium octadecylphosphonate in tri-n-octylphosphine oxide, was studied with 1H and {1H}31P NMR spectroscopy as well as ESI-MS and XPS. The identity of the surface ligands was inferred from reaction of nanocrystals with Me3Si-X (X = -S-SiMe3, -Se-SiMe3, -Cl and -S-(CH2CH2O)4OCH3)) and unambiguous assignment of the organic byproducts, O,O'-bis(trimethylsilyl)octadecylphosphonic acid ester and O,O'-bis(trimethylsilyl)ocatdecylphosphonic acid anhydride ester. Nanocrystals isolated from these reactions have undergone exchange of the octadecylphosphonate ligands for -X as was shown by 1H NMR (X = -S-(CH2CH2O)4OCH3) and XPS (X = -Cl). Addition of free thiols to as prepared nanocrystals results in binding of the thiol to the particle surface and quenching of the nanocrystal fluorescence. Isolation of the thiol-ligated nanocrystals shows this chemisorption proceeds without displacement of the octadecylphosphonate ligands, suggesting the presence of unoccupied Lewis-acidic sites on the particle surface. In the presence of added triethylamine, however, the octadecylphosphonate ligands are readily displaced from the particle surface as was shown with 1H and {1H}31P NMR. These results, in conjunction with previous literature reports, indicate that as-prepared nanocrystal surfaces are terminated by X-type binding of octadecylphosphonate moieties to a layer of excess cadmium ions.

  20. Histidine 352 (His352) and Tryptophan 355 (Trp355) Are Essential for Flax UGT74S1 Glucosylation Activity toward Secoisolariciresinol

    PubMed Central

    Ghose, Kaushik; McCallum, Jason; Sweeney-Nixon, Marva; Fofana, Bourlaye

    2015-01-01

    Flax secoisolariciresinol diglucoside (SDG) lignan is a natural phytoestrogen for which a positive role in metabolic diseases is emerging. Until recently however, much less was known about SDG and its monoglucoside (SMG) biosynthesis. Lately, flax UGT74S1 was identified and characterized as an enzyme sequentially glucosylating secoisolariciresinol (SECO) into SMG and SDG when expressed in yeast. However, the amino acids critical for UGT74S1 glucosyltransferase activity were unknown. A 3D structural modeling and docking, site-directed mutagenesis of five amino acids in the plant secondary product glycosyltransferase (PSPG) motif, and enzyme assays were conducted. UGT74S1 appeared to be structurally similar to the Arabidopsis thaliana UGT72B1 model. The ligand docking predicted Ser357 and Trp355 as binding to the phosphate and hydroxyl groups of UDP-glucose, whereas Cys335, Gln337 and Trp355 were predicted to bind the 7-OH, 2-OCH3 and 17-OCH3 of SECO. Site-directed mutagenesis of Cys335, Gln337, His352, Trp355 and Ser357, and enzyme assays revealed an alteration of these binding sites and a significant reduction of UGT74S1 glucosyltransferase catalytic activity towards SECO and UDP-glucose in all mutants. A complete abolition of UGT74S1 activity was observed when Trp355 was substituted to Ala355 and Gly355 or when changing His352 to Asp352, and an altered metabolite profile was observed in Cys335Ala, Gln337Ala, and Ser357Ala mutants. This study provided for the first time evidence that Trp355 and His352 are critical for UGT74S1’s glucosylation activity toward SECO and suggested the possibility for SMG production in vitro. PMID:25714779

  1. Solid-state thermolysis of [MnO]{sub 12} containing molecular clusters into novel MnO nano- and microparticles

    SciTech Connect

    Chen Lingyun; Xing Hang; Shen Yongming; Bai Junfeng; Jiang Guoqing

    2009-06-15

    Novel MnO nano- and microparticles including spherical nanoparticles and various micropolyhedra of pyramid-like, truncated rectangular pyramid-like, cubic, and rhombic dodecahedral particles, were controllably synthesized via solid-state thermolysis of inorganic core containing molecular clusters [Mn{sub 12}O{sub 12}(O{sub 2}CR){sub 16}(H{sub 2}O){sub 4}] (R=C{sub 6}H{sub 5}, CH{sub 3}, and C{sub 6}H{sub 5}OCH{sub 2}) in a conventional horizontal tube furnace. Among them, pyramid-like, truncated rectangular pyramid-like, cubic, and rhombic dodecahedral MnO submicroscale particles were reported for the first time. The products were characterized by XRD, XPS, Raman spectrum, SEM, EDX, TEM and HRTEM. During the reaction process, thermolysis temperature, reaction time, and different molecular clusters {l_brace}Mn12{r_brace} precursors with different organic ligands as well play important roles in determining the sizes and shapes of the final products. The formed MnO nanospheres from [Mn{sub 12}O{sub 12}(O{sub 2}CC{sub 6}H{sub 5}){sub 16}(H{sub 2}O){sub 4}] at 400 deg. C for 10 h exhibited weak ferromagnetic behavior at low temperature which may be due to the size-effect of nanomaterials. Furthermore, the possible formation mechanism was also discussed. - Graphical abstract: Novel MnO nano- and microparticles were controlled synthesized by solid-state thermolysis of inorganic core containing molecular clusters [Mn{sub 12}O{sub 12}(O{sub 2}CR){sub 16}(H{sub 2}O){sub 4}] (R=C{sub 6}H{sub 5}, CH{sub 3}, and C{sub 6}H{sub 5}OCH{sub 2}) in a conventional tubular furnace.

  2. Reaching and abandoning the furthest ice extent during the Last Glacial Maximum in the Alps

    NASA Astrophysics Data System (ADS)

    Ivy-Ochs, Susan; Wirsig, Christian; Zasadni, Jerzy; Hippe, Kristina; Christl, Marcus; Akçar, Naki; Schluechter, Christian

    2016-04-01

    During the Last Glacial Maximum (LGM) in the European Alps (late Würm) local ice caps and extensive ice fields in the high Alps fed huge outlet glaciers that occupied the main valleys and extended onto the forelands as piedmont lobes. Records from numerous sites suggest advance of glaciers beyond the mountain front by around 30 ka (Ivy-Ochs 2015 and references therein). Reaching of the maximum extent occurred by about 27-26 ka, as exemplified by dates from the Rhein glacier area (Keller and Krayss, 2005). Abandonment of the outermost moraines at sites north and south of the Alps was underway by about 24 ka. In the high Alps, systems of transection glaciers with transfluences over many of the Alpine passes dominated, for example, at Grimsel Pass in the Central Alps (Switzerland). 10Be exposure ages of 23 ± 1 ka for glacially sculpted bedrock located just a few meters below the LGM trimline in the Haslital near Grimsel Pass suggest a pulse of ice surface lowering at about the same time that the foreland moraines were being abandoned (Wirsig et al., 2016). Widespread ice surface lowering in the high Alps was underway by no later than 18 ka. Thereafter, glaciers oscillated at stillstand and minor re-advance positions on the northern forelands for several thousand years forming the LGM stadial moraines. Final recession back within the mountain front took place by 19-18 ka. Recalculation to a common basis of all published 10Be exposure dates for boulders situated on LGM moraines suggests a strong degree of synchrony for the timing of onset of ice decay both north and south of the Alps. Ivy-Ochs, S., 2015, Cuadernos de investigación geográfica 41: 295-315. Keller, O., Krayss, E., 2005, Vierteljahrschr. Naturforsch. Gesell. Zürich 150: 69-85. Wirsig, C. et al., 2016, J. Quat. Sci. 31: 46-59.

  3. 1,1,3,3-Tetramethylguanidine solvated lanthanide aryloxides: pre-catalysts for intramolecular hydroalkoxylation.

    PubMed

    Janini, Thomas E; Rakosi, Robert; Durr, Christopher B; Bertke, Jeffrey A; Bunge, Scott D

    2009-12-21

    The synthesis and structural characterization of six 1,1,3,3-tetramethylguanidine (H-TMG) solvated lanthanide aryloxide complexes are reported. Ln[N{Si(CH3)3}2]3 (Ln = Nd, La) was reacted with two equivalents of both H-TMG and HOAr {HOAr = HOC6H2(CMe3)2-2,6 (H-DBP) or HOC6H2(CMe3)2-2,6-CH3-4 (H-4MeDBP)} and one equivelent of ethanol (HOEt) to yield the corresponding [Nd(H-TMG)2(4MeDBP)2(OEt)] (1) and [La(H-TMG)2(DBP)2(OEt)] (2). Compounds 1 and 2 were further reacted with 4-pentyn-1-ol {HO(CH2)3C[triple bond]CH} to isolate [Nd(H-TMG)2(4MeDBP)2{O(CH2)3C[triple bond]CH}] (3) and [La(H-TMG)2(DBP)2{O(CH2)3C[triple bond]CH}] (4), respectively. Three equivalents of HOAr and one equivalent of H-TMG were additionally reacted with Ln[N{Si(CH3)3}2]3 to generate [Nd(4MeDBP)3(H-TMG)] (5) and [La(DBP)3(H-TMG)] (6). In order to examine the formation of 1-6, the interaction of H-TMG and HOAr was further examined in solution and the hydrogen bonded complexes (H-TMG:HOAr), 7 and 8, were isolated. Upon successful isolation of 1-6, the utility of 1, 2, 4 and 5 as pre-catalysts for the intramolecular hydroalkoxylation of 4-pentyn-1-ol was investigated. The bulk powders for all complexes were found to be in agreement with the crystal structures based on elemental analyses, FT-IR spectroscopy, and 1H and 13C NMR investigations.

  4. Structural and Magnetic Diversity in Alkali-Metal Manganate Chemistry: Evaluating Donor and Alkali-Metal Effects in Co-complexation Processes.

    PubMed

    Uzelac, Marina; Borilovic, Ivana; Amores, Marco; Cadenbach, Thomas; Kennedy, Alan R; Aromí, Guillem; Hevia, Eva

    2016-03-24

    By exploring co-complexation reactions between the manganese alkyl Mn(CH2SiMe3)2 and the heavier alkali-metal alkyls M(CH2SiMe3) (M=Na, K) in a benzene/hexane solvent mixture and in some cases adding Lewis donors (bidentate TMEDA, 1,4-dioxane, and 1,4-diazabicyclo[2,2,2] octane (DABCO)) has produced a new family of alkali-metal tris(alkyl) manganates. The influences that the alkali metal and the donor solvent impose on the structures and magnetic properties of these ates have been assessed by a combination of X-ray, SQUID magnetization measurements, and EPR spectroscopy. These studies uncover a diverse structural chemistry ranging from discrete monomers [(TMEDA)2 MMn(CH2SiMe3)3] (M=Na, 3; M=K, 4) to dimers [{KMn(CH2SiMe3)3 ⋅C6 H6}2] (2) and [{NaMn(CH2SiMe3)3}2 (dioxane)7] (5); and to more complex supramolecular networks [{NaMn(CH2SiMe3)3}∞] (1) and [{Na2Mn2 (CH2SiMe3)6 (DABCO)2}∞] (7)). Interestingly, the identity of the alkali metal exerts a significant effect in the reactions of 1 and 2 with 1,4-dioxane, as 1 produces coordination adduct 5, while 2 forms heteroleptic [{(dioxane)6K2Mn2 (CH2SiMe3)4(O(CH2)2OCH=CH2)2}∞] (6) containing two alkoxide-vinyl anions resulting from α-metalation and ring opening of dioxane. Compounds 6 and 7, containing two spin carriers, exhibit antiferromagnetic coupling of their S=5/2 moments with varying intensity depending on the nature of the exchange pathways.

  5. Enantioselective DNA condensation induced by heptameric lanthanum helical supramolecular enantiomers.

    PubMed

    Bao, Fei-Fei; Xu, Xin-Xin; Zhou, Wen; Pang, Chun-Yan; Li, Zaijun; Gu, Zhi-Guo

    2014-09-01

    DNA condensation induced by a pair of heptameric La(III) helical enantiomers M-[La7(S-L)6(CO3)(NO3)6(OCH3)(CH3OH)7]·2CH3OH·5H2O and P-[La7(R-L)6(CO3)(NO3)6(OCH3)(CH3OH)5(H2O)2]·2CH3OH·4H2O (M-La and P-La, L=2-(2-hydroxybenzylamino)-3-carbamoylpropanoic acid) has been investigated by UV/vis spectroscopy, fluorescence spectroscopy, CD spectroscopy, EMSA, RALS, DLS, and SEM. The enantiomers M-La and P-La could induce CT-DNA condensation at a low concentration as observed in UV/vis spectroscopy. DNA condensates possessed globular nanoparticles with nearly homogeneous sizes in solid state determined by SEM (ca. 250 nm for M-La and ca. 200 nm for P-La). The enantiomers bound to DNA through electrostatic attraction and hydrogen bond interactions in a major groove, and rapidly condensed free DNA into its compact state. DNA decompaction has been acquired by using EDTA as disassembly agent, and analyzed by UV/vis spectroscopy, CD spectroscopy and EMSA. Moreover, the enantiomers M-La and P-La displayed discernible discrimination in DNA interaction and DNA condensation, as well as DNA decondensation. Our study suggested that lanthanum(III) enantiomers M-La and P-La were efficient DNA packaging agents with potential applications in gene delivery.

  6. Hydrothermal synthesis of copper selenides with controllable phases and morphologies from an ionic liquid precursor

    NASA Astrophysics Data System (ADS)

    Liu, Xiaodi; Duan, Xiaochuan; Peng, Peng; Zheng, Wenjun

    2011-12-01

    Cu2-xSe nanocrystals and CuSe nanoflakes are successfully synthesized through a convenient hydrothermal method from an ionic liquid precursor 1-n-butyl-3-ethylimidazolium methylselenite ([BMIm][SeO2(OCH3)]). The phases and morphologies of the copper selenides can be controlled by simply changing the atom ratio of Cu/Se in the reactants and reaction temperature. Furthermore, it is found that the [BMIm][SeO2(OCH3)] not only serves as Se source but also has influence on the shapes of CuSe nanoflakes. The adsorption of alkyl imidazolium rings ([BMIm]+) onto the (0001) facets of covellite CuSe prohibits the growth in the [0001] direction, and CuSe nuclei growth mainly processes along the six symmetric directions (+/-[01&cmb.macr;11], +/-[101&cmb.macr;1&cmb.macr;], and +/-[1&cmb.macr;100]) to form flakelike CuSe. The obtained copper selenides are characterized by XRD, SEM, EDS, XPS, TEM, and HRTEM. The results indicate that the Cu2-xSe nanocrystals are nearly spherical particles with an average diameter of about 20 nm, the hexagonal CuSe nanoflakes are single crystals with an edge length of 100-400 nm and a thickness of 25-50 nm. The potential formation mechanism of the copper selenides is also proposed.Cu2-xSe nanocrystals and CuSe nanoflakes are successfully synthesized through a convenient hydrothermal method from an ionic liquid precursor 1-n-butyl-3-ethylimidazolium methylselenite ([BMIm][SeO2(OCH3)]). The phases and morphologies of the copper selenides can be controlled by simply changing the atom ratio of Cu/Se in the reactants and reaction temperature. Furthermore, it is found that the [BMIm][SeO2(OCH3)] not only serves as Se source but also has influence on the shapes of CuSe nanoflakes. The adsorption of alkyl imidazolium rings ([BMIm]+) onto the (0001) facets of covellite CuSe prohibits the growth in the [0001] direction, and CuSe nuclei growth mainly processes along the six symmetric directions (+/-[01&cmb.macr;11], +/-[101&cmb.macr;1&cmb.macr;], and +/-[1

  7. Towards H2-rich gas production from unmixed steam reforming of methane: Thermodynamic modeling

    NASA Astrophysics Data System (ADS)

    Lima da Silva, Aline; Müller, Iduvirges Lourdes

    2011-10-01

    In this work, the Gibbs energy minimization method is applied to investigate the unmixed steam reforming (USR) of methane to generate hydrogen for fuel cell application. The USR process is an advanced reforming technology that relies on the use of separate air and fuel/steam feeds to create a cyclic process. Under air flow (first half of the cycle), a bed of Ni-based material is oxidized, providing the heat necessary for the steam reforming that occurs subsequently during fuel/steam feed stage (second half of the cycle). In the presence of CaO sorbent, high purity hydrogen can be produced in a single reactor. In the first part of this work, it is demonstrated that thermodynamic predictions are consistent with experimental results from USR isothermal tests under fuel/steam feed. From this, it is also verified that the reacted NiO to CH4 (NiOreacted/CH4) molar ratio is a very important parameter that affects the product gas composition and decreases with time. At the end of fuel/steam flow, the reforming reaction is the most important chemical mechanism, with H2 production reaching ∼75 mol%. On the other hand, at the beginning of fuel/steam feed stage, NiO reduction reactions dominate the equilibrium system, resulting in high CO2 selectivity, negative steam conversion and low concentrations of H2. In the second part of this paper, the effect of NiOreacted/CH4 molar ratio on the product gas composition and enthalpy change during fuel flow is investigated at different temperatures for inlet H2O/CH4 molar ratios in the range of 1.2-4, considering the USR process operated with and without CaO sorbent. During fuel/steam feed stage, the energy demand increases as time passes, because endothermic reforming reaction becomes increasingly important as this stage nears its end. Thus, the duration of the second half of the cycle is limited by the conditions under which auto-thermal operation can be achieved. In absence of CaO, H2 at concentrations of approximately 73 mol% can

  8. Climate change and control of the southeastern Bering Sea pelagic ecosystem

    NASA Astrophysics Data System (ADS)

    Hunt, George L., Jr.; Stabeno, Phyllis; Walters, Gary; Sinclair, Elizabeth; Brodeur, Richard D.; Napp, Jeffery M.; Bond, Nicholas A.

    2002-12-01

    We propose a new hypothesis, the Oscillating Control Hypothesis (OCH), which predicts that pelagic ecosystem function in the southeastern Bering Sea will alternate between primarily bottom-up control in cold regimes and primarily top-down control in warm regimes. The timing of spring primary production is determined predominately by the timing of ice retreat. Late ice retreat (late March or later) leads to an early, ice-associated bloom in cold water (e.g., 1995, 1997, 1999), whereas no ice, or early ice retreat before mid-March, leads to an open-water bloom in May or June in warm water (e.g., 1996, 1998, 2000). Zooplankton populations are not closely coupled to the spring bloom, but are sensitive to water temperature. In years when the spring bloom occurs in cold water, low temperatures limit the production of zooplankton, the survival of larval/juvenile fish, and their recruitment into the populations of species of large piscivorous fish, such as walleye pollock ( Theragra chalcogramma), Pacific cod ( Gadus macrocephalus) and arrowtooth flounder ( Atheresthes stomias). When continued over decadal scales, this will lead to bottom-up limitation and a decreased biomass of piscivorous fish. Alternatively, in periods when the bloom occurs in warm water, zooplankton populations should grow rapidly, providing plentiful prey for larval and juvenile fish. Abundant zooplankton will support strong recruitment of fish and will lead to abundant predatory fish that control forage fish, including, in the case of pollock, their own juveniles. Piscivorous marine birds and pinnipeds may achieve higher production of young and survival in cold regimes, when there is less competition from large piscivorous fish for cold-water forage fish such as capelin ( Mallotus villosus). Piscivorous seabirds and pinnipeds also may be expected to have high productivity in periods of transition from cold regimes to warm regimes, when young of large predatory species of fish are numerous enough to

  9. Tuning the reactivity of Fe(V)(O) toward C-H bonds at room temperature: effect of water.

    PubMed

    Singh, Kundan K; Tiwari, Mrityunjay k; Ghosh, Munmun; Panda, Chakadola; Weitz, Andrew; Hendrich, Michael P; Dhar, Basab B; Vanka, Kumar; Sen Gupta, Sayam

    2015-02-16

    The presence of an Fe(V)(O) species has been postulated as the active intermediate for the oxidation of both C-H and C═C bonds in the Rieske dioxygenase family of enzymes. Understanding the reactivity of these high valent iron-oxo intermediates, especially in an aqueous medium, would provide a better understanding of these enzymatic reaction mechanisms. The formation of an Fe(V)(O) complex at room temperature in an aqueous CH3CN mixture that contains up to 90% water using NaOCl as the oxidant is reported here. The stability of Fe(V)(O) decreases with increasing water concentration. We show that the reactivity of Fe(V)(O) toward the oxidation of C-H bonds, such as those in toluene, can be tuned by varying the amount of water in the H2O/CH3CN mixture. Rate acceleration of up to 60 times is observed for the oxidation of toluene upon increasing the water concentration. The role of water in accelerating the rate of the reaction has been studied using kinetic measurements, isotope labeling experiments, and density functional theory (DFT) calculations. A kinetic isotope effect of ∼13 was observed for the oxidation of toluene and d8-toluene showing that C-H abstraction was involved in the rate-determining step. Activation parameters determined for toluene oxidation in H2O/CH3CN mixtures on the basis of Eyring plots for the rate constants show a gain in enthalpy with a concomitant loss in entropy. This points to the formation of a more-ordered transition state involving water molecules. To further understand the role of water, we performed a careful DFT study, concentrating mostly on the rate-determining hydrogen abstraction step. The DFT-optimized structure of the starting Fe(V)(O) and the transition state indicates that the rate enhancement is due to the transition state's favored stabilization over the reactant due to enhanced hydrogen bonding with water.

  10. New type of single chain magnet: pseudo-one-dimensional chain of high-spin Co(II) exhibiting ferromagnetic intrachain interactions.

    PubMed

    Tangoulis, V; Lalia-Kantouri, M; Gdaniec, M; Papadopoulos, Ch; Miletic, V; Czapik, A

    2013-06-03

    Two new six-coordinated high-spin Co(II) complexes have been synthesized through the reactions of Co(II) salts with dipyridylamine (dpamH) and 5-nitro-salicylaldehyde (5-NO2-saloH) or 3-methoxy-salicylaldehyde (3-OCH3-saloH) under argon atmosphere: [Co(dpamH)2(5-NO2-salo)]NO3 (1) and [Co(dpamH)2(3-OCH3-salo)]NO3·1.3 EtOH·0.4H2O (2). According to the crystal packing of compound 1, two coordination cations are linked with two nitrate anions into a cyclic dimeric arrangement via N-H···O and C-H···O hydrogen bonds. In turn, these dimers are assembled into (100) layers through π-π stacking interactions between inversion-center related pyridine rings of the dpamH ligands. The crystal packing of compound 2 reveals a 1D assembly consisting solely from the coordination cations, which is formed by π-π stacking interactions between pyridine rings of one of the dpamH along the [010] and another 1D assembly of the coordination cations and nitrate anions through the N-H···O hydrogen-bonding interactions along the [001] direction. All complexes were magnetically characterized, and a new approximation method was used to fit the magnetic susceptibility data in the whole temperature range 2-300 K on the basis of an empirical expression which allows the treatment of each cobalt(II) ion in axial symmetry as an effective spin S(eff) = 1/2. In zero-field, dynamic magnetic susceptibility measurements show slow magnetic relaxation below 5.5 K for compound 2. The slow dynamics may originate from the motion of broad domain walls and is characterized by an Arrhenius law with a single energy barrier Δr/k(B) = 55(1) K for the [10-1488 Hz] frequency range. In order to reveal the importance of the crystal packing in the SCM behavior, a gentle heating process to 180 °C was carried out to remove the solvent molecules. The system, after heating, undergoes a major but not complete collapse of the network retaining to a small percentage its SCM character.

  11. Synthesis and characterization of amine-bridged bis(phenolate)lanthanide alkoxides and their application in the controlled polymerization of rac-lactide and rac-β-butyrolactone.

    PubMed

    Nie, Kun; Fang, Lei; Yao, Yingming; Zhang, Yong; Shen, Qi; Wang, Yaorong

    2012-10-15

    A series of neutral lanthanide alkoxides supported by an amine-bridged bis(phenolate) ligand were synthesized, and their catalytic behaviors for the polymerization of rac-lactide (LA) and rac-β-butyrolactone (BBL) were explored. The reactions of (C(5)H(5))(3)Ln(THF) with amine-bridged bis(phenol) LH(2) [L = Me(2)NCH(2)CH(2)N{CH(2)-(2-OC(6)H(2)Bu(t)(2)-3,5)}(2)] in a 1:1 molar ratio in THF for 1 h and then with 1 equiv each of 2,2,2-trifluoroethanol, benzyl alcohol, and 2-propanol gave the neutral lanthanide alkoxides LLn(OCH(2)CF(3))(THF) [Ln = Y (1), Yb (2), Er (3), Sm (4)], LY(OCH(2)Ph)(THF) (5), and LY(OPr(i))(THF) (6), respectively. These lanthanide alkoxides are sensitive to moisture, and the yttrium complex [(LY)(2)(μ-OPr(i))(μ-OH)] (7) was also isolated as a byproduct during the synthesis of complex 6. Complexes 1-6 were well characterized by elemental analyses and IR and NMR spectroscopy in the cases of complexes 1 and 4-6. The definitive molecular structures of all of these complexes were determined by single-crystal X-ray analysis. It was found that complexes 1-6 can initiate efficiently the ring-opening polymerization of rac-LA and rac-BBL in a controlled manner. For rac-LA, polymerization gave polymers with very narrow molecular weight distributions (PDI ≤ 1.12) and very high heterotacticity (P(r) up to 0.99). The observed activity-increasing order is in agreement with the order of the ionic radii, whereas the order for stereoselectivity is in the reverse order. For rac-BBL polymerization, the resultant polymers have narrow molecular distributions (PDI ≤ 1.26) and high syndiotacticity (P(r) up to 0.83). It is worth noting that the activity-decreasing order Yb > Er > Y > Sm is observed for rac-BBL polymerization, which is opposite to the order of ionic radii and to the order of activity for rac-LA polymerization. The ionic radii of lanthanide metals have no obvious effect on the stereoselectivity for rac-BBL polymerization, which is quite

  12. Synthesis of enantiopure oxorhenium(V) and arylimidorhenium(V) "3 + 2" Schiff base complexes. X-ray diffraction, cyclic voltammetry, UV-vis, and circular dichroism characterizations.

    PubMed

    Béreau, V M; Khan, S I; Abu-Omar, M M

    2001-12-17

    Two new oxorhenium(V) and two new arylimidorhenium(V) complexes of the Schiff base ligands 2-hydroxybenzaldehyde-((1R,2S)-1-amino-2-indanol)imine (1) (H(2)L(1)) and 3-(1-adamantyl)-2-hydroxy-5-methylbenzaldehyde-((1R,2S)-1-amino- 2-indanol)imine (2) (H(2)L(2)) have been prepared from the reaction of the precursor Re(O)(PPh(3))(2)Cl(3), Re(NC(6)H(5))(PPh(3))(2)Cl(3), or Re(NC(6)H(4)OCH(3))(PPh(3))(2)Cl(3) and the free ligands H(2)L(1,2). The complexes Re(O)(HL(1))(L(1)) (3), Re(O)(HL(2))(L(2)) (4), Re(NC(6)H(5))(HL(1))(L(1)) (5), and Re(NC(6)H(4)OCH(3))(HL(1))(L(1)) (6) have been isolated and fully characterized by IR, (1)H NMR, circular dichroism, LRMS-FAB, and elemental analysis. All the complexes have a chiral center at rhenium. A single enantiomer is obtained in all cases. Suitable crystals of 3 and 5 were used in X-ray structural determinations. Crystal data: (3) C(32)H(27)N(2)O(5)Re.CH(2)Cl(2), orthorhombic, P2(1)2(1)2(1), a = 9.5599(16) A, b = 9.9579(16) A, c = 31.712(5) A, V = 3018.9(9) A(3), T = 100(2) K, Z = 4. (5) C(40)H(38)N(3)O(5)Re, monoclinic, P2(1), a = 9.286(3) A, b = 18.759(6) A, c = 9.957(3) A, beta = 102.817(6) degrees, V = 1691.3(10) A(3), T = 100(2) K, Z = 2. The major characteristic of these complexes is the presence of two coordination modes for the Schiff base ligands on rhenium, a tridentate ligand (noted L(1,2)) and another bidentate ligand (noted HL(1,2)). In the latter, the -OH group of the indanol is free and tilts away from the coordination sphere. X-ray structural analyses in conjunction with circular dichroism were used to assign the absolute configuration at rhenium (C). Cyclic voltammetry, UV-vis, and circular dichroism data are presented and discussed. The complexes were found to be highly stable and to resist reduction even when treated with organic phosphanes.

  13. First-principles thermochemistry for silicon species in the decomposition of tetraethoxysilane.

    PubMed

    Phadungsukanan, Weerapong; Shekar, Shraddha; Shirley, Raphael; Sander, Markus; West, Richard H; Kraft, Markus

    2009-08-06

    (OH)3(OCH3), Si(OH)2(OCH3)2, the silicon dimers (CH3)3-SiOSi(CH3)3 and SiH3OSiH3, and the smaller hydrocarbon species CH4, CO2, C2H4, and C2H6 are highlighted as the important species.

  14. Morphological and Phase Controlled Tungsten Based Nanoparticles: Synthesis and Characterization of Scheelites, Wolframites, and Oxides Nanomaterials.

    PubMed

    Hernandez-Sanchez, Bernadette A; Boyle, Timothy J; Pratt, Harry D; Rodriguez, Mark A; Brewer, Luke N; Dunphy, Darren R

    2008-11-11

    For the first time tungsten based nanoparticles (WNPs) of scheelite (MWO(4); M = Ca, Sr, Ba, Pb), wolframite (MWO(4); M = Mn, Fe, Zn & (Mg(0.60)Mn(0.17)Fe(0.26))WO(4)), and the oxide (WO(3) and W(18)O(49)) were synthesized from solution precipitation (i.e.,trioctylamine or oleic acid) and solvothermal (i.e., benzyl alcohol) routes. The resultant WNPs were prepared directly from tungsten (VI) ethoxide (W(OCH(2)CH(3))(6), 1) and stoichiometeric mixtures of the following precursors: [Ca(N(SiMe(3))(2))(2)](2) (2), Pb(N(SiMe(3))(2))(2) (3), Mn[(mu-Mes)(2)Mn(Mes)](2) (4), [Fe(mu-Mes)(Mes)](2) (5), Fe(CO)(5) (6), H(+)[Ba(2)(mu(3)-ONep)(mu-ONep)(2)(ONep)(ONep)(3)(py)](-) (2) (7), H(+)[Sr(5)(mu(4)-O)(mu(3)-ONep)(4)(mu-ONep)(4)(ONep)(py)(4)](-) (8), and [Zn(Et)(ONep)(py)](2) (9) where Mes = C(6)H(2)(CH(3))(3)-2,4,6, ONep = OCH(2)CMe(3), Et = CH(2)CH(3), and py = pyridine. Through these routes, the WNP morphologies were found to be manipulated by the processing conditions, while precursor selection influenced the final phase observed. For the solution precipitation route, 1 yielded (5 x 100 nm) W(18)O(49) rods while stochiometeric reactions between 1 and (2 - 9) generated homogenous sub 30 nm nano-dots, -diamonds, -rods, and -wires for the MWO(4) systems. For the solvothermal route, 1 was found to produce wires of WO(3) with aspect ratios of 20 while (1 & 2) formed 10 - 60 nm CaWO(4) nanodots. Room temperature photoluminescent (PL) emission properties of select WNPs were also examined with fluorescence spectroscopy (lambda(ex) = 320 nm). Broad PL emissions = 430, 420, 395, 420 nm were noted for 5 x 100 nm W(18)O(49) rods, 5 x 15 nm, CaWO(4) rods, 10 - 30 nm CaWO(4) dots, and 10 nm BaWO(4) diamonds, respectively.

  15. Determination of the boundary of carbon formation for dry reforming of methane in a solid oxide fuel cell

    NASA Astrophysics Data System (ADS)

    Assabumrungrat, S.; Laosiripojana, N.; Piroonlerkgul, P.

    The boundary of carbon formation for the dry reforming of methane in direct internal reforming solid oxide fuel cells (DIR-SOFCs) with different types of electrolyte (i.e., an oxygen ion-conducting electrolyte (SOFC-O 2-) and a proton-conducting electrolyte (SOFC-H +)) was determined by employing detailed thermodynamic analysis. It was found that the required CO 2/CH 4 ratio decreased with increasing temperature. The type of electrolyte influenced the boundary of carbon formation because it determined the location of water formed by the electrochemical reaction. The extent of the electrochemical reaction also played an important role in the boundary of carbon formation. For SOFC-O 2-, the required CO 2/CH 4 ratio decreased with the increasing extent of the electrochemical reaction due to the presence of electrochemical water in the anode chamber. Although for SOFC-H + the required CO 2/CH 4 ratio increased with the increasing extent of the electrochemical reaction at high operating temperature (T > 1000 K) following the trend previously reported for the case of steam reforming of methane with addition of water as a carbon suppresser, an unusual opposite trend was observed at lower operating temperature. The study also considered the use of water or air as an alternative carbon suppresser for the system. The required H 2O/CH 4 ratio and air/CH 4 ratio were determined for various inlet CO 2/CH 4 ratios. Even air is a less attractive choice compared to water due to the higher required air/CH 4 ratio than the H 2O/CH 4 ratio; however, the integration of exothermic oxidation and the endothermic reforming reactions may make the use of air attractive. Water was found to be more effective than carbon dioxide in suppressing the carbon formation at low temperatures but their effect was comparable at high temperatures. Although the results from the study were based on calculations of the SOFCs with different electrolytes, they are also useful for selecting suitable feed

  16. Plasma induced UV/VUV damage during Si and GaN device fabrication

    NASA Astrophysics Data System (ADS)

    Tatsumi, Tetsuya

    2012-10-01

    Plasma induced damages (PID) on semiconductor devices have been widely reported. Materials and the interface between stacked materials can be degraded by ions and photons during plasma processes. In this report, I focus on the effect of ultraviolet (UV) and vacuum ultraviolet (VUV) radiation on various devices. In the fabrication of Si-CMOS devices, high-density plasmas are used for dry etching. The light from plasma is absorbed by the materials when its energy is greater than the band gap (Eg). For example, the Eg of the gate SiO2 is about 8.8 eV; consequently the plasma emissions with wavelengths lower than 150 nm are absorbed by SiO2. These VUV lights degrade the surface structure of SiO2 and increase its wet etch rate [1]. SiOCH and ArF photo resist have been used to realize high-speed devices with low power consumption. These materials have a very weak bond, so there are sometimes problems such as increased dielectric constant in SiOCH or a roughening or wiggling of ArF resist caused by UV/VUV [2]. Plasma emission can also affect the electrical and/or optical properties of devices. I investigated the effect of radiation on the interface-trap density (Dit) of a SiN/Si structure [3]. When photons in the UV region (200--300 nm) were irradiated, the Dit increased and a negative charge was generated in the interface. This indicates that VUV/UV radiation transmitting through the upper dielectrics causes the electrical characteristics of underlying devices to fluctuate. GaN-based semiconductors are used for optoelectronic device applications, so I also investigated the PID of a GaN/InGaN/GaN stacked structure. The samples were exposed to Cl2 plasma emission and analyzed by using photoluminescence (PL). PL intensity decreased when the plasma emission was irradiated. UV radiation (<360 nm) affects damage formation at the InGaN active layer [4]. Monitoring VUV/UV and understanding its effect on surface eactions, film damage, and electrical and/or optical performance are

  17. Interaction of metal ions with biomolecular ligands: how accurate are calculated free energies associated with metal ion complexation?

    PubMed

    Gutten, Ondrej; Beššeová, Ivana; Rulíšek, Lubomír

    2011-10-20

    To address fundamental questions in bioinorganic chemistry, such as metal ion selectivity, accurate computational protocols for both the gas-phase association of metal-ligand complexes and solvation/desolvation energies of the species involved are needed. In this work, we attempt to critically evaluate the performance of the ab initio and DFT electronic structure methods available and recent solvation models in calculations of the energetics associated with metal ion complexation. On the example of five model complexes ([M(II)(CH(3)S)(H(2)O)](+), [M(II)(H(2)O)(2)(H(2)S)(NH(3))](2+), [M(II)(CH(3)S)(NH(3))(H(2)O)(CH(3)COO)], [M(II)(H(2)O)(3)(SH)(CH(3)COO)(Im)], [M(II)(H(2)S)(H(2)O)(CH(3)COO)(PhOH)(Im)](+) in typical coordination geometries) and four metal ions (Fe(2+), Cu(2+), Zn(2+), and Cd(2+); representing open- and closed-shell and the first- and second-row transition metal elements), we provide reference values for the gas-phase complexation energies, as presumably obtained using the CCSD(T)/aug-cc-pVTZ method, and compare them with cheaper methods, such as DFT and RI-MP2, that can be used for large-scale calculations. We also discuss two possible definitions of interaction energies underlying the theoretically predicted metal-ion selectivity and the effect of geometry optimization on these values. Finally, popular solvation models, such as COSMO-RS and SMD, are used to demonstrate whether quantum chemical calculations can provide the overall free enthalpy (ΔG) changes in the range of the expected experimental values for the model complexes or match the experimental stability constants in the case of three complexes for which the experimental data exist. The data presented highlight several intricacies in the theoretical predictions of the experimental stability constants: the covalent character of some metal-ligand bonds (e.g., Cu(II)-thiolate) causing larger errors in the gas-phase complexation energies, inaccuracies in the treatment of solvation of the

  18. Water and complex organic chemistry in the cold dark cloud Barnard 5: Observations and Models

    NASA Astrophysics Data System (ADS)

    Wirström, Eva; Charnley, Steven B.; Taquet, Vianney; Persson, Carina M.

    2015-08-01

    Studies of complex organic molecule (COM) formation have traditionally been focused on hot cores in regions of massive star formation, where chemistry is driven by the elevated temperatures - evaporating ices and allowing for endothermic reactions in the gas-phase. As more sensitive instruments have become available, the types of objects known to harbour COMs like acetaldehyde (CH3CHO), dimethyl ether (CH3OCH3), methyl formate (CH3OCHO), and ketene (CH2CO) have expanded to include low mass protostars and, recently, even pre-stellar cores. We here report on the first in a new category of objects harbouring COMs: the cold dark cloud Barnard 5 where non-thermal ice desorption induce complex organic chemistry entirely unrelated to local star-formation.Methanol, which only forms efficiently on the surfaces of dust grains, provide evidence of efficient non-thermal desorption of ices in the form of prominent emission peaks offset from protostellar activity and high density tracers in cold molecular clouds. A study with Herschel targeting such methanol emission peaks resulted in the first ever detection of gas-phase water offset from protostellar activity in a dark cloud, at the so called methanol hotspot in Barnard 5.To model the effect a transient injection of ices into the gas-phase has on the chemistry of a cold, dark cloud we have included gas-grain interactions in an existing gas-phase chemical model and connected it to a chemical reaction network updated and expanded to include the formation and destruction paths of the most common COMs. Results from this model will be presented.Ground-based follow-up studies toward the methanol hotspot in B5 have resulted in the detection of a number of COMs, including CH2CO, CH3CHO, CH3OCH3, and CH3OCHO, as well as deuterated methanol (CH2DOH). Observations have also confirmed that COM emission is extended and not localised to a core structure. The implications of these observational and theoretical studies of B5 will be discussed

  19. Laboratory studies of some halogenated ethanes and ethers: Measurements of rates of reaction with OH and of infrared absorption cross-sections

    NASA Astrophysics Data System (ADS)

    Brown, Anne C.; Canosa-Mas, Carlos E.; Douglas Parr, A.; Wayne, Richard P.

    We have measured, using a conventional discharge-flow resonance-fluorescence technique, the rates of reaction between the hydroxyl radical and a series of halogenated ethanes and ethers for the temperature range 230-423 K. Our measurements gave the following Arrhenius expressions (units are cm 3 molecule -1 s -1): CF 2HCH 3 (HFC-152), 14.2 × 10 -13 exp-(1050/ T); CF 2ClCH 3 (HCFC-142b), 2.6 × 10 -13 exp-(1230/ T); CFCl 2CH 3 (HCFC-141b), 5.8 × 10 -13 exp-(1100/ T); CF 3CFH 2 (HFC-134a), 5.8 × 10 -13 exp-(1350/ T); CF 3CF 2H (HFC-125), 2.8 × 10 -13 exp-(1350/ T); CF 3CCl 2H (HCFC-123), 11.8 × 10 -13 exp-(900/ T); CF 2HOCF 2CFClH, (enflurane), 6.1 × 10 -13 exp-(1080/ T); CFH 2OCH(CF 3) 2, (sevoflurane), 15.3 × 10 -13 exp-(900/ T). In two cases, we measured rate constants only at room temperature: CF 3CClBrH (halothane), 6 × 10 -14 and CF 2HOCClHCF 3 (isoflurane), 2.1 × 10 -14. We also report the following values for the integrated absorption cross-sections of the compounds in the spectral region 800-1200 cm -1 in units of cm -2 atm -1: CF 2HCH 3, 1155; CF 2ClCH 3, 1422; CFCl 2CH 3, 1995; CF 3CFH 2, 2686; CF 3CF 2H, 1970, CF 3CCl 2H, 1411; CF 3CClBrH, 1400; CF 2HOCF 2CFClH, 4800; CF 2HOCClHCF 3, 3900; CFH 2OCH(CF 3) 2, 2550. We use our measurements to calculate ozone depletion potentials and greenhouse warming potentials relative to CFCl 3 for each compound.

  20. 10Be surface exposure dating of rock glaciers in Larstigtal, Tyrol, Austria

    NASA Astrophysics Data System (ADS)

    Ivy-Ochs, S.; Kerschner, H.; Maisch, M.; Christl, M.; Kubik, P. W.; Schluchter, C.

    2009-04-01

    In the context of Lateglacial and Holocene climate change research, rock glaciers (creeping mountain permafrost) also play an important role. They are phenomena of discontinuous alpine permafrost and as such good indicators for the mean annual air temperature for the period they are active. We have 10Be surface exposure dated boulders from two relict rock glaciers in Larstigtal, Austria. This is the type area for a postulated mid-Holocene cold period called the Larstig oscillation. The period of activity was suggested to be of similar age as the mid-Holocene Frosnitz advance of glaciers in the Venediger Mountains farther to the east (Patzelt and Bortenschlager, 1973). For rock glaciers of this size to be active at 2200 m a.s.l. in Larstig valley would have required a significant drop in temperatures, thus a marked mid-Holocene cold pulse, for at least several centuries at around 7.0 ka. In contrast, our exposure dates show that the rock glaciers stabilized during the early Preboreal (Ivy-Ochs et al., submitted). We see no distinct pattern with respect to exposure age and boulder location on the rock glaciers. This implies that for our site the blocks did not acquire inherited 10Be during exposure in the free rock face, in the talus at the base of the slope, or during transport on the rock glaciers. Our data point to final stabilization of the Larstigtal rock glaciers in the earliest Holocene and not in the middle Holocene. Combined with data from other archives (Nicolussi et al., 2005), there appears to have been no time window in the middle Holocene long enough for rock glaciers of the size and at the elevation of the Larstig site to have formed. Ivy-Ochs, S., Kerschner, H., Maisch, M., Christl, M., Kubik, P.W., Schlüchter, C., Latest Pleistocene and Holocene glacier variations in the European Alps. Quaternary Science Reviews (submitted). Nicolussi, K., Kaufmann, M., Patzelt, G., van der Plicht, J., Thurner, A., 2005. Holocene tree-line variability in the Kauner

  1. In situ 14C depth profile of subsurface vein quartz samples from Macraes Flat New Zealand

    NASA Astrophysics Data System (ADS)

    Kim, K. J.; Lal, D.; Englert, P. A. J.; Southon, J.

    2007-06-01

    We present results of measurements of cosmogenic in situ 14C produced in a quartz vein from Macraes Flat, East Otago, New Zealand, where concentrations of in situ produced 10Be and 26Al were previously studied by Kim and Englert [Earth Planet. Sci. Lett. 223 (2004) 113]. 14C was extracted from the quartz samples up to depths of 400 g cm-2 using a low temperature wet extraction method [D. Lal, A.J.T. Jull, Nucl. Instr. and Meth. B 92 (1994) 291]. Based on the results for 10Be and 26Al, we expected that the 14C activity in the samples would be at saturation levels, in equilibrium with erosion. The surface exposure age of this site was found to be about 25 000 years using 10Be and 26Al at the surface, with a surface erosion rate of at least 10-3 cm/y [K.J. Kim, P.A.J. Englert, Earth Planet. Sci. Lett. 223 (2004) 113]. The measured 14C activities were compared with those expected from spallation of Si and O in quartz by energetic neutrons and fast muons, and from capture of negative muons in O in quartz [B. Heisinger, A.J.T. Jull, D. Lal, P. Kubik, S. Ivy-Ochs, K. Knie, E. Nolte, Earth Planet. Sci. Lett. 200 (2002) 357; B. Heisinger, D. Lal, A.J.T. Jull, P. Kubik, S. Ivy-Ochs, S. Neumaier, K. Knie, V. Lazarev, E. Nolte, Earth Planet. Sci. Lett. 200 (2002) 345]. Surprisingly, we found that the 14C activities were significantly greater than those expected, by factors of 2 3, especially in samples of depths <200 g cm-2. We suspect that the excess 14C probably resulted from capture of thermal neutrons in nitrogen present in the fluid inclusions in quartz. This study shows that great care has to be taken in measurements of in situ 14C in quartz, especially in samples exposed near sea level and greater depths, where rates of spallation produced 14C are low.

  2. Denudation of Actively Growing Mountain Ranges in the Foreland of NE Tibet Inferred From in- Situ Produced Cosmogenic Be-10

    NASA Astrophysics Data System (ADS)

    Palumbo, L.; Hetzel, R.; Tao, M.; Li, X.

    2007-12-01

    At the northeastern edge of the Tibetan Plateau ranges bounded by active thrust faults offer the unique opportunity to study the competing effects of uplift and erosion during the early stages of mountain building. Owing to along- strike variations in relief, slope, and lithology, these ranges are an ideal target for studying the influence of topography, lithology, and active faulting on denudation. Here we report spatially-averaged erosion rates for catchments situated along two of these ranges based on Be-10 concentrations of quartz in stream sediments. The Yumu Shan and the western Long Shou Shan are about 60 km long and their overall shape as well as the presence of wind gaps illustrates their vertical-lateral growth during Plio-Quaternary thrust faulting (Hetzel et al. 2004a). Erosion rates determined so far for 20 small catchments are variable and range from 20 to 550 mm/kyr. The observed variability results from at least three factors: (1) the erosion rate in catchments exposing the same lithology is positively correlated with relief and mean slope, (2) weakly consolidated Cretaceous sediments generally erode faster than low-grade Paleozoic bedrock, and (3) the erosion rate seems to decrease from the centre of the fault-bounded ranges towards their propagating tips. As rates of thrust faulting and rock uplift in the region (600-1200 mm/kyr; Hetzel et al., 2004a, b) exceed the denudation rates, the active growth of mountains and the lateral growth of Tibet has not yet come to rest. References Hetzel, R., Tao, M., Niedermann, S., Strecker, M.R., Ivy-Ochs, S., Kubik, P.W., Gao, B. (2004a). Implications of the fault scaling law for the growth of topography: Mountain ranges in the broken foreland of NE Tibet, Terra Nova 16, 157-162. Hetzel, R., Tao, M., Stokes, S., Niedermann, S., Ivy-Ochs, S., Gao, B., Strecker, M.R., Kubik, P.W. (2004b). Late Pleistocene-Holocene slip rate of the Zhangye thrust (Qilian Shan, China) and implications for the active growth of the

  3. Thermal Chemistry of Cp*W(NO)(CH2CMe3)(H)(L) Complexes (L = Lewis Base).

    PubMed

    Fabulyak, Diana; Handford, Rex C; Holmes, Aaron S; Levesque, Taleah M; Wakeham, Russell J; Patrick, Brian O; Legzdins, Peter; Rosenfeld, Devon C

    2017-01-03

    The complexes trans-Cp*W(NO)(CH2CMe3)(H)(L) (Cp* = η(5)-C5Me5) result from the treatment of Cp*W(NO)(CH2CMe3)2 in n-pentane with H2 (∼1 atm) in the presence of a Lewis base, L. The designation of a particular geometrical isomer as cis or trans indicates the relative positions of the alkyl and hydrido ligands in the base of a four-legged piano-stool molecular structure. The thermal behavior of these complexes is markedly dependent on the nature of L. Some of them can be isolated at ambient temperatures [e.g., L = P(OMe)3, P(OPh)3, or P(OCH2)3CMe]. Others undergo reductive elimination of CMe4 via trans to cis isomerization to generate the 16e reactive intermediates Cp*W(NO)(L). These intermediates can intramolecularly activate a C-H bond of L to form 18e cis complexes that may convert to the thermodynamically more stable trans isomers [e.g., Cp*W(NO)(PPh3) initially forms cis-Cp*W(NO)(H)(κ(2)-PPh2C6H4) that upon being warmed in n-pentane at 80 °C isomerizes to trans-Cp*W(NO)(H)(κ(2)-PPh2C6H4)]. Alternatively, the Cp*W(NO)(L) intermediates can effect the intermolecular activation of a substrate R-H to form trans-Cp*W(NO)(R)(H)(L) complexes [e.g., L = P(OMe)3 or P(OCH2)3CMe; R-H = C6H6 or Me4Si] probably via their cis isomers. These latter activations are also accompanied by the formation of some Cp*W(NO)(L)2 disproportionation products. An added complication in the L = P(OMe)3 system is that thermolysis of trans-Cp*W(NO)(CH2CMe3)(H)(P(OMe)3) results in it undergoing an Arbuzov-like rearrangement and being converted mainly into [Cp*W(NO)(Me)(PO(OMe)2)]2, which exists as a mixture of two isomers. All new complexes have been characterized by conventional and spectroscopic methods, and the solid-state molecular structures of most of them have been established by single-crystal X-ray crystallographic analyses.

  4. Light activated nitric oxide releasing materials

    NASA Astrophysics Data System (ADS)

    Muizzi Casanas, Dayana Andreina

    The ability to control the location and dosage of biologically active molecules inside the human body can be critical to maximizing effective treatment of cardiovascular diseases like angina. The current standard of treatment relies on the metabolism of organonitrate drugs into nitric oxide (NO), which are not specific, and also show problems with densitization with long-term use. There is a need then to create a treatment method that gives targeted release of NO. Metal-nitrosyl (M-NO) complexes can be used for delivery of NO since the release of NO can be controlled with light. However, the NO-releasing drug must be activated with red light to ensure maximum penetration of light through tissue. However, the release of NO from M-NO complexes with red-light activation is a significant challenge since the energy required to break the metal-NO bond is usually larger than the energy provided by red light. The goal of this project was to create red- sensitive, NO-releasing materials based on Ru-salen-nitrosyl compounds. Our approach was to first modify Ru salen complexes to sensitize the photochemistry for release of NO after red light irradiation. Next, we pursued polymerization of the Ru-salen complexes. We report the synthesis and quantitative photochemical characterization of a series of ruthenium salen nitrosyl complexes. These complexes were modified by incorporating electron donating groups in the salen ligand structure at key locations to increase electron density on the Ru. Complexes with either an --OH or --OCH3 substituent showed an improvement in the quantum yield of release of NO upon blue light irradiation compared to the unmodified salen. These --OH and --OCH3 complexes were also sensitized for NO release after red light activation, however the red-sensitive complexes were unstable and showed ligand substitution on the order of minutes. The substituted complexes remained sensitive for NO release, but only after blue light irradiation. The Ru

  5. Structures in solid state and solution of dimethoxy curcuminoids: regioselective bromination and chlorination

    PubMed Central

    2013-01-01

    Background Several papers described the structure of curcumin and some other derivatives in solid and in solution. In the crystal structure of curcumin, the enol H atom is located symmetrically between both oxygen atoms of the enolone fragment with an O···O distance of 2.455 Å, which is characteristic for symmetrical H-bonds. In the solution, the geometry of the enolone fragment is attributed to the inherent disorder of the local environment, which solvates one of the basic sites better than the other, stabilizing one tautomer over the other. In this paper, how the position of methoxy groups in dimethoxy curcuminoids influence the conformation of molecules and how the halogen atoms change it when they are bonded at α-position in keto-enol part of molecules is described. Results Six isomers of dimethoxy curcuminoids were prepared. Conformations in solid state, which were determined by X-ray single crystallography and 1H MAS and 13C CPMAS NMR measurements, depend on the position of methoxy groups in curcuminoid molecules. In solution, a fast equilibrium between both keto-enol forms exists. A theoretical calculation finding shows that the position of methoxy groups changes the energy of HOMO and LUMO. An efficient protocol for the highly regioselective bromination and chlorination leading to α-halogenated product has been developed. All α-halogenated compounds are present mainly in cis keto-enol form. Conclusions The structures in solid state of dimethoxy curcuminoids depend on the position of methoxy groups. The NMR data of crystalline solid samples of 3,4-diOCH3 derivative, XRD measurements and X-ray structures lead us to the conclusion that polymorphism exists in solids. The same conclusion can be done for 3,5-diOCH3 derivative. In solution, dimethoxy curcuminoids are present in the forms that can be described as the coexistence of two equivalent tautomers being in fast equilibrium. The position of methoxy groups has a small influence on the enolic hydrogen

  6. Bridging silyl groups in sigma-bond metathesis and [1, 2] shifts. An experimental and computational study of the reaction between cerium metallocenes and MeOSiMe3

    SciTech Connect

    Werkema, Evan; Yahia, Ahmed; Maron, Laurent; Eisenstein, Odile; Andersen, Richard

    2010-04-21

    The reaction of Cp'2CeH (Cp' = 1,2,4-(Me3C)3C5H2 ) with MeOSiMe3 gives Cp'2CeOMe and HSiMe3 and the reaction of the metallacycle, Cp'[(Me3C)2C5H2C(Me) 2CH2]Ce, with MeOSiMe3 yields Cp'2CeOCH2SiMe3, formed from hypothetical Cp'2CeCH2OSiMe3 by a [1, 2] shift also known as a silyl-Wittig rearrangement. Although both cerium products are alkoxides, they are formed by different pathways. DFT calculations on the reaction of the model metallocene, Cp2CeH, and MeOSiMe3 show that the lowest energy pathway is a H for OMe exchange at Ce that occurs by way of a sigma-bond metathesis transition state as SiMe3 exchanges partners. The formation of Cp2CeOCH2SiMe3 occurs by way of a low activation barrier [1, 2]shift of the SiMe3 group in Cp2CeCH2OSiMe3. Calculations on a model metallacycle, Cp[C5H4C(Me)2CH2]Ce, show that the metallacycle favors CH bond activation over sigma-bond metathesis involving the transfer of the SiMe3 group in good agreement with experiment. The sigma-bond metathesis involving the transfer of SiMe3 and the [1, 2]shift of SiMe3 reactions have in common a pentacoordinate silicon at the transition states. A molecular orbital analysis illustrates the connection between these two Si-O bond cleavage reactions and traces the reason why they occur for a silyl but not for an alkyl group to the difference in energy required to form a pentacoordinate silicon or carbon atom in the transition state. This difference clearly distinguishes a silyl from an alkyl group as shown in the study of"Pyrolysis of Tetramethylsilane Yielding Free d-orbitals by Seyferth and Pudvin in ChemTech 1981, 11, 230-233".

  7. Mono-N-methylation of primary amines with alkyl methyl carbonates over Y faujasites. 2. Kinetics and selectivity.

    PubMed

    Selva, Maurizio; Tundo, Pietro; Perosa, Alvise

    2002-12-27

    In the presence of a Na-exchanged Y faujasite, the reaction of primary aromatic amines 1 with 2-(2-methoxyethoxy)methylethyl carbonate [MeO(CH(2))(2)O(CH(2))(2)OCO(2)Me, 2a] yields the corresponding mono-N-methyl derivatives ArNHMe with selectivity up to 95%, at substantially quantitative conversions. At 130 degrees C, the reaction can be run under diffusion-free conditions and is strongly affected by the solvent polarity: for instance, in going from xylene (epsilon(r) = 2.40) to triglyme (epsilon(r) = 7.62) as the solvent, the pseudo-first-order rate constant for the aniline (1a) disappearance shows a 5-fold decrease. In DMF (epsilon(r) = 38.25), the same reaction does not occur at all. Competitive adsorption of the solvent and the substrate onto the catalytic sites accounts for this result. The behavior of alkyl-substituted anilines ZC(6)H(4)NH(2) [Z = p-Me, p-Et, p-Pr, p-(n-Bu) (1b-e); Z = 3,5-di-tert-butyl- and 2,4,6-tri-tert-butylanilines (1f,g)] and p-alkoxyanilines p-ZC(6)H(4)NH(2) [Z = OMe, OEt, OPr, O-n-Bu (1b'-e')] clearly indicates a steric effect of ring substituents: as diffusion of the amine into the catalytic pores is hindered, the reaction hardly proceeds and the mono-N-methyl selectivity (S(M/D)) drops as well. Moreover, the strength of adsorption of the amine onto the catalyst influences the rate and the selectivity as well: the reaction of p-anisidine and p-toluidine-despite the higher nucleophilicity of these compounds-is slower and even less selective with respect to aniline. From a mechanistic viewpoint, the intermediacy of carbamates ArN(Me)CO(2)R [R = MeO(CH(2))(2)O(CH(2))(2)] is suggested. At 90 degrees C, the reaction of benzylamine (7)-a model for aliphatic amines-with dimethyl carbonate shows that the reaction outcome can be improved by tuning the amphoteric properties of the catalyst: in going from CsY to the more acidic LiY zeolite, methylation is not only more selective (S(M/D) ratio increases from 77% to 84%) but even much faster (Cs

  8. Synthesis, characterization and luminescence of europium perchlorate with MABA-Si complex and coating structure SiO2 @Eu(MABA-Si) luminescence nanoparticles.

    PubMed

    Fu, Zhi-Fang; Li, Wen-Xian; Bai, Juan; Bao, Jin-Rong; Cao, Xiao-Fang; Zheng, Yu-Shan

    2016-07-19

    This article reports a novel category of coating structure SiO2 @Eu(MABA-Si) luminescence nanoparticles (NPs) consisting of a unique organic shell, composed of perchlorate europium(III) complex, and an inorganic core, composed of silica. The binary complex Eu(MABA-Si)3 ·(ClO4 )3 ·5H2 O was synthesized using HOOCC6 H4 N(CONH(CH2 )3 Si(OCH2 CH3 )3 )2 (MABA-Si) and was used as a ligand. Furthermore, the as-prepared silica NPs were successfully coated with the -Si(OCH2 CH3 )3 group of MABA-Si to form Si-O-Si chemical bonds by means of the hydrolyzation of MABA-Si. The binary complexes were characterized by elemental analysis, molar conductivity and coordination titration analysis. The results indicated that the composition of the binary complex was Eu(MABA-Si)3 ·(ClO4 )3 ·5H2 O. Coating structure SiO2 @Eu(MABA-Si) NPs were characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM) and infrared (IR) spectra. Based on the SEM and TEM measurements, the diameter of core-SiO2 particles was ~400 and 600 nm, and the thickness of the cladding layer Eu(MABA-Si) was ~20 nm. In the binary complex Eu(MABA-Si)3 ·(ClO4 )3 ·5H2 O, the fluorescence spectra illustrated that the energy of the ligand MABA-Si transferred to the energy level for the excitation state of europium(III) ion. Coating structure SiO2 @Eu(MABA-Si) NPs exhibited intense red luminescence compared with the binary complex. The fluorescence lifetime and fluorescence quantum efficiency of the binary complex and of the coating structure NPs were also calculated. The way in which the size of core-SiO2 spheres influences the luminescence was also studied. Moreover, the luminescent mechanisms of the complex were studied and explained.

  9. Theoretical study on the gas-phase reaction mechanism between palladium monoxide and methane.

    PubMed

    Yang, Hua-Qing; Hu, Chang-Wei; Gao, Chao; Yang, Meng-Yao; Li, Fang-Ming; Li, Cai-Qin; Li, Xiang-Yuan

    2011-12-01

    The gas-phase reaction mechanism between palladium monoxide and methane has been theoretically investigated on the singlet and triplet state potential energy surfaces (PESs) at the CCSD(T)/AVTZ//B3LYP/6-311+G(2d, 2p), SDD level. The major reaction channel leads to the products PdCH(2) + H(2)O, whereas the minor channel results in the products Pd + CH(3)OH, CH(2)OPd + H(2), and PdOH + CH(3). The minimum energy reaction pathway for the formation of main products (PdCH(2) + H(2)O), involving one spin inversion, prefers to start at the triplet state PES and afterward proceed along the singlet state PES, where both CH(3)PdOH and CH(3)Pd(O)H are the critical intermediates. Furthermore, the rate-determining step is RS-CH(3) PdOH → RS-2-TS1cb → RS-CH(2)Pd(H)OH with the rate constant of k = 1.48 × 10(12) exp(-93,930/RT). For the first C-H bond cleavage, both the activation strain ΔE(≠)(strain) and the stabilizing interaction ΔE(≠)(int) affect the activation energy ΔE(≠), with ΔE(≠)(int) in favor of the direct oxidative insertion. On the other hand, in the PdCH(2) + H(2) O reaction, the main products are Pd + CH(3)OH, and CH(3)PdOH is the energetically preferred intermediate. In the CH(2)OPd + H(2) reaction, the main products are Pd + CH(3)OH with the energetically preferred intermediate H(2)PdOCH(2). In the Pd + CH(3)OH reaction, the main products are CH(2)OPd + H(2), and H(2)PdOCH(2) is the energetically predominant intermediate. The intermediates, PdCH(2), H(2) PdCO, and t-HPdCHO are energetically preferred in the PdC + H(2), PdCO + H(2), and H(2)Pd + CO reactions, respectively. Besides, PdO toward methane activation exhibits higher reaction efficiency than the atom Pd and its first-row congener NiO.

  10. Mechanistic aspects of hydrosilylation catalyzed by (ArN=)Mo(H)(Cl)(PMe3)3.

    PubMed

    Khalimon, Andrey Y; Shirobokov, Oleg G; Peterson, Erik; Simionescu, Razvan; Kuzmina, Lyudmila G; Howard, Judith A K; Nikonov, Georgii I

    2012-04-02

    The reaction of (ArN=)MoCl(2)(PMe(3))(3) (Ar = 2,6-diisopropylphenyl) with L-Selectride gives the hydrido-chloride complex (ArN=)Mo(H)(Cl)(PMe(3))(3) (2). Complex 2 was found to catalyze the hydrosilylation of carbonyls and nitriles as well as the dehydrogenative silylation of alcohols and water. Compound 2 does not show any productive reaction with PhSiH(3); however, a slow H/D exchange and formation of (ArN=)Mo(D)(Cl)(PMe(3))(3) (2(D)) was observed upon addition of PhSiD(3). Reactivity of 2 toward organic substrates was studied. Stoichiometric reactions of 2 with benzaldehyde and cyclohexanone start with dissociation of the trans-to-hydride PMe(3) ligand followed by coordination and insertion of carbonyls into the Mo-H bond to form alkoxy derivatives (ArN=)Mo(Cl)(OR)(PMe(2))L(2) (3: R = OCH(2)Ph, L(2) = 2 PMe(3); 5: R = OCH(2)Ph, L(2) = η(2)-PhC(O)H; 6: R = OCy, L(2) = 2 PMe(3)). The latter species reacts with PhSiH(3) to furnish the corresponding silyl ethers and to recover the hydride 2. An analogous mechanism was suggested for the dehydrogenative ethanolysis with PhSiH(3), with the key intermediate being the ethoxy complex (ArN=)Mo(Cl)(OEt)(PMe(3))(3) (7). In the case of hydrosilylation of acetophenone, a D-labeling experiment, i.e., a reaction of 2 with acetophenone and PhSiD(3) in the 1:1:1 ratio, suggests an alternative mechanism that does not involve the intermediacy of an alkoxy complex. In this particular case, the reaction presumably proceeds via Lewis acid catalysis. Similar to the case of benzaldehyde, treatment of 2 with styrene gives trans-(ArN=)Mo(H)(η(2)-CH(2)═CHPh)(PMe(3))(2) (8). Complex 8 slowly decomposes via the release of ethylbenzene, indicating only a slow insertion of styrene ligand into the Mo-H bond of 8.

  11. Investigation of cellular and protein interactions with model self-assembled monolayer surfaces

    NASA Astrophysics Data System (ADS)

    Tegoulia, Vassiliki Apostolou

    Self-assembled monolayers (SAMs) of alkanethiolates on gold have been used to investigate the effect of substrate surface properties on bacterial and blood cell adhesion in the presence and absence of blood proteins. Protein adsorption and binding strength on SAMs as well as complement activation by these model surfaces were also studied. It is hoped that information gained, regarding factors that influence biological processes, will lead to strategies for designing materials and surfaces that specifically inhibit cell adhesion and protein adsorption. Single component SAMs of the general formula HS(CH2) 10X, where X = CH3, CH2OH. COOH and CH2(OCH 2CH2)3OH, and two component mixed SAMs created from binary solutions of HS(CH2), OCH3 and HS(CH 2)10CH2OH, were used. Adhesion was investigated under well-defined flow conditions. Adhesion was found to be higher for the hydrophobic methyl and minimal for the tri(ethyleneoxide) terminated SAM. Preincubation of the SAMs with fibrinogen led to an increase in cell adhesion for bacteria and a decrease for leukocyte adhesion. The effect of surface chemistry on protein adsorption was studied for three blood proteins, fibrinogen, fibronectin and albumin. Adsorption was found to be higher on the hydrophobic CH3 surface and lower but comparable for the other surfaces while proteins adsorbed strongly on all surfaces. SAMs were also used to evaluate complement activation by foreign surfaces. The hydroxyl rich SAMs were found to activate complement more significantly than the anionic carboxyl and the hydrophobic methyl terminated SAMs. A surface modification was introduced to incorporate a zwitterionic phosphorylcholine (PC) group on a hydroxyl monolayer in an effort to create a biomimetic surface that could minimize cell adhesion and protein adsorption. The good antifouling properties of the phosphorylcholine modified surface led to the synthesis of a novel phosphorylcholine functionalized thiol. Single component and two component

  12. Interstellar ice analogs: H2O ice mixtures with CH3OH and NH3 in the far-IR region

    NASA Astrophysics Data System (ADS)

    Giuliano, B. M.; Martín-Doménech, R.; Escribano, R. M.; Manzano-Santamaría, J.; Muñoz Caro, G. M.

    2016-08-01

    Context. New spectroscopic observations in the far-infrared (IR) range are expected from future planned missions. Although water ice is the only species detected so far in interstellar ices in this range, the presence of ice mixtures requires laboratory characterization of the corresponding spectra. Aims: We present an investigation on far-IR spectra of binary ice mixtures relevant in various astrophysical environments. The foremost goal is to compare the spectroscopic features of the ice mixtures to those of pure ices, and to search for changes in peak frequencies, intensities, and band strengths of the main bands. Methods: Mixtures H2O:CH3OH and H2O:NH3 of different ratios have been deposited on a diamond substrate at astrophysically relevant conditions. We measured the spectra in the near- and mid-IR regions to derive ice column densities that were subsequently used to calculate the apparent band strengths in the far-IR region. We also designed theoretical models to study these mixtures and to predict their spectra. Results: We recorded spectra of amorphous phases for H2O:CH3OH mixtures of different compositions, that is 1:1, 3:1, and 10:1 at 8 K, and compared these mixtures to those obtained after warming. This process involves the appearance of new spectral features and changes in band shapes and band strengths. We also compared the spectra to those of the pure species and to theoretical predictions. We measured apparent band strengths for all the observed features. For H2O:NH3 mixtures, the ratios selected were 3:1, 1:1, and 1:3. In this case the spectral variations are even more marked than for the water:methanol samples. Conclusions: Band strengths in the far-IR are missing in astrophysics literature for ice mixtures. The results presented here are valuable for detecting the presence and composition of such mixtures from future space observations in this spectral region.

  13. Synthesis and structural characterization of a tetramolybdate, (Mo sub 4 O sub 12 (C sub 8 H sub 6 N sub 4 )) sup 2 minus , containing a bridging phthalazine-1-hydrazido(2-) ligand. Comparison to the structure of (Mo sub 4 O sub 10 (OMe) sub 2 (NNMePh) sub 2 ) sup 2 minus , a tetramolybdate species exhibiting ligation to a terminal monodentate hydrazido(2-) group

    SciTech Connect

    Shaikh, S.N.; Zubieta, J. )

    1988-06-01

    The reaction of (n-Bu{sub 4}N){sub 2}(Mo{sub 2}O{sub 7}) with 1-methyl-1-phenylhydrazine in CH{sub 2}Cl{sub 2}-methanol yields the tetranuclear poly oxomolybdate (n-Bu{sub 4}N){sub 2}(Mo{sub 4}O{sub 10}(OCH{sub 3}){sub 2}(NNMePh){sub 2}) (I). Complex I displays the methoxy-bridged binuclear core (MoO(NNMePh)({mu}-OCH{sub 3}){sub 2}MoO(NNMePh)){sup 2+}, bridged by two double-bridging bidentate (MoO{sub 4}){sup 2{minus}} units. Complex I is structurally related to the class of tetranuclear poly oxomolybdates coordinated to small organic molecules, (Mo{sub 4}O{sub 6-10}L{sub 1}L{sub 2}){sup n-}. The reaction of (n-Bu{sub 4}N){sub 2}(Mo{sub 2}O{sub 7}) with the potentially chelating and bridging hydrazino ligand hydrazinophthalazine, H{sub 2}NNH(C{sub 8}H{sub 5}N{sub 2}) (H{sub 2}-NNH-pht), yields the analogous tetranuclear species (n-Bu{sub 4}N){sub 2}(Mo{sub 4}O{sub 12}(HNN-pht))(II). Although structurally related to I, II reveals a number of distinctive features. The binuclear core (Mo{sub 2}O{sub 4}HNN-pht){sup 2+} displays a bridging oxo group and a bidentate bridging phthalazine moiety, in contrast to the two bridging methoxy groups of I. The Mo centers of this core are nonequivalent, one exhibiting MoO{sub 4}N{sub 2} coordination and the other (MoO{sub 5}N). The bridging (MoO{sub 4}){sup 2{minus}} moieties display unexceptional geometry. The {sup 17}O NMR spectra of I, II, and the related 1,4-dihydrazinophthalazine derivative (Mo{sub 4}O{sub 11}(C{sub 8}H{sub 6}N{sub 6})){sup 2{minus}} are consistent with the solid-state structures, exhibiting resonances in the regions assigned to doubly bridging Mo{sub 2}O groups (350-450 ppm) and to terminal MoO groups (750-950 ppm). Crystal data for the complexes are reported. 28 references, 3 figures, 7 tables.

  14. Decomposition and cycloaddition reactions of hfacac and syntheses and structures of Ln{sub 2}{sup III}(hfacac){sub 4}(bdmap){sub 2}(H{sub 2}O){sub 2}(THF){sub 2}, Ln{sup III}Cu{sup II}(bdmapH){sub 2}(hfacac){sub 2}(O{sub 2}CCF{sub 3})L, and Ln{sup III}Cu{sub 2}{sup II}(hfacac)(bdmap){sub 3}(O{sub 2}CCH{sub 3}){sub 2}(O{sub 2}CCF{sub 3})(hfacacH) (Ln = Y, Pr, Nd; hfacac = Hexafluoroacetylacetonato; bdmap = 1,3-bis(dimethylamino)-2-propanolato; L = 2-methyl-2,4,6-tris(trifluoromethyl)-1,3-dioxane-4,6-diolato)

    SciTech Connect

    Wang, S.; Pang, Z.; Smith, K.D.L.; Hua, Y.; Deslippe, C.; Wagner, M.J.

    1995-02-15

    The reactions of Ln(hfacac){sub 3} with the bdmapH ligand and Cu(OCH{sub 3}){sub 2} or Cu{sub 2}(O{sub 2}CCH{sub 3}){sub 4}(H{sub 2}O){sub 2} have been investigated where hfacac = hexafluoroacetylacetonato, bdmapH = 1,3-bis(dimethylamino)-2-propanol. The hfacac ligand in these reactions has been found to undergo decomposition or cycloaddition with 1,1,1-trifluoro-2,2-propanediol. Two dinuclear compounds, Ln{sub 2}(hfacac){sub 4}(bdmap){sub 2}(H{sub 2}O){sub 2}(THF){sub 2}, (1, Ln = Pr) and LnCu(bdmapH){sub 2}-(hfacac){sub 2}(O{sub 2}CCF{sub 3})L (Ln = Pr, 2a; Y, 2b; L = 2-methyl-2,4,6-tris(trifluoromethyl)-1,3-dioxane-4,6-diolato), have been isolated from the reaction of Ln(hfacac){sub 3} with Cu(OCH{sub 3}){sub 2} and bdmapH in a 1:1:2 ratio in THF. These two compounds also were obtained by independent syntheses. A trinuclear compound, LnCu{sub 2}(hfacac)(bdmap){sub 3}(O{sub 2}-CCH{sub 3}){sub 2}(O{sub 2}CCF{sub 3})(hfacacH) (Ln = Nd, 3a; Pr, 3b), was obtained from the reaction of Ln(hfacac){sub 3} with Cu{sub 2}(O{sub 2}-CCH{sub 3}){sub 4}(H{sub 2}O){sub 2} and bdmapH in a 1:1:3 ratio in THF. The crystal structures of these compounds have been determined by X-ray diffraction analyses. Their thermal behavior has been examined by thermogravimetric analysis. The magnetic properties of compounds 1, 2b, and 3b were examined by EPR and magnetic susceptibility measurements.

  15. THE SEARCH FOR A COMPLEX MOLECULE IN A SELECTED HOT CORE REGION: A RIGOROUS ATTEMPT TO CONFIRM TRANS-ETHYL METHYL ETHER TOWARD W51 e1/e2

    SciTech Connect

    Carroll, P. Brandon; McGuire, Brett A.; Blake, Geoffrey A.; Apponi, A. J.; Ziurys, L. M.; Remijan, Anthony

    2015-01-20

    An extensive search has been conducted to confirm transitions of trans-ethyl methyl ether (tEME, C{sub 2}H{sub 5}OCH{sub 3}), toward the high-mass star forming region W51 e1/e2 using the 12 m Telescope of the Arizona Radio Observatory at wavelengths from 2 mm and 3 mm. In short, we cannot confirm the detection of tEME toward W51 e1/e2 and our results call into question the initial identification of this species by Fuchs et al. Additionally, re-evaluation of the data from the original detection indicates that tEME is not present toward W51 e1/e2 in the abundance reported by Fuchs and colleagues. Typical peak-to-peak noise levels for the present observations of W51 e1/e2 were between 10 and 30 mK, yielding an upper limit of the tEME column density of ≤1.5 × 10{sup 15} cm{sup –2}. This would make tEME at least a factor of two times less abundant than dimethyl ether (CH{sub 3}OCH{sub 3}) toward W51 e1/e2. We also performed an extensive search for this species toward the high-mass star forming region Sgr B2(N-LMH) with the National Radio Astronomy Observatory 100 m Green Bank Telescope. No transitions of tEME were detected and we were able to set an upper limit to the tEME column density of ≤4 × 10{sup 14} cm{sup –2} toward this source. Thus, we are able to show that tEME is not a new molecular component of the interstellar medium and that an exacting assessment must be carried out when assigning transitions of new molecular species to astronomical spectra to support the identification of large organic interstellar molecules.

  16. Selective transformation of carbonyl ligands to organic molecules

    SciTech Connect

    Cutler, A.R.

    1992-05-12

    Studies on the carbonylation of ({eta}{sup 5}-indenyl)(L)(CO)Ru-R complexes (L = CO, PPh{sub 3}; R = CH{sub 2}OMe, CH{sub 3}) have been completed. Particularly noteworthy is that the methoxymethyl complexes readily transform to their acyl derivatives under mild conditions that leave their iron congeners inert towards CO. Surprisingly, even ({eta}{sup 5}-indenyl)(PPh{sub 3}){sub 2}Ru-CH{sub 3} carbonylates and gives ({eta}{sup 5}-indenyl)(PPh{sub 3})(CO)Ru-C(O)CH{sub 3}. Mechanistic studies on the non catalyzed'' hydrosilation of the manganese acyls (CO){sub 5}Mn-C(O)CH{sub 2}R (R = H, OCH{sub 3}, CH{sub 3}) with Et{sub 3}SiH and of cobalt acetyls (CO){sub 3}(PR{sub 3})CoC(O)CH{sub 3} with several monohydrosilanes have been completed. The cobalt acetyls cleanly give ethoxysilanes (not acetaldehyde), and the manganese acyls provide {alpha}-siloxyvinyl complexes Z-(CO){sub 5}Mn-C(OSiEt{sub 3})=CHR (R = H, CH{sub 3}, OCH{sub 3}). Carbonylation and protolytic cleavage of the latter generate pyruvoyl complexes (CO){sub 5}Mn-COCOR (R = CH{sub 3}, CH{sub 2}CH{sub 3}), formally the products of net double carbonylation'' sequences. Studies in progress are concerned with how manganese complexes as diverse as (CO){sub 5}Mn-Y (Y = C(O)R, R, BR - but not SiMe{sub 3} or Mn(CO){sub 5}) and ({eta}{sup 3}-C{sub 3}H{sub 5})Mn(CO){sub 2}L (but not CpMn(CO){sub 3} or CpMn(CO){sub 2}({eta}{sup 2}HSiR{sub 3})) function as efficient hydrosilation catalysts towards Cp(CO){sub 2}FeC(O)CH{sub 3}, for example. These reactions cleanly afford fully characterized {alpha}-siloxyethyl complexes Fp-CH(OSiR{sub 3})CH{sub 3} under conditions where typically Rh(1) hydrosilation catalysts are inactive. Several of these manganese complexes also catalytically hydrosilate organic esters, including lactones, to their ethers R-CH{sub 2}OR; these novel ester reductions occur quantitatively at room temperature and appear to be general in scope.

  17. Selective transformation of carbonyl ligands to organic molecules. Progress report, September 1, 1989--November 14, 1992

    SciTech Connect

    Cutler, A.R.

    1992-05-12

    Studies on the carbonylation of ({eta}{sup 5}-indenyl)(L)(CO)Ru-R complexes (L = CO, PPh{sub 3}; R = CH{sub 2}OMe, CH{sub 3}) have been completed. Particularly noteworthy is that the methoxymethyl complexes readily transform to their acyl derivatives under mild conditions that leave their iron congeners inert towards CO. Surprisingly, even ({eta}{sup 5}-indenyl)(PPh{sub 3}){sub 2}Ru-CH{sub 3} carbonylates and gives ({eta}{sup 5}-indenyl)(PPh{sub 3})(CO)Ru-C(O)CH{sub 3}. Mechanistic studies on the ``non catalyzed`` hydrosilation of the manganese acyls (CO){sub 5}Mn-C(O)CH{sub 2}R (R = H, OCH{sub 3}, CH{sub 3}) with Et{sub 3}SiH and of cobalt acetyls (CO){sub 3}(PR{sub 3})CoC(O)CH{sub 3} with several monohydrosilanes have been completed. The cobalt acetyls cleanly give ethoxysilanes (not acetaldehyde), and the manganese acyls provide {alpha}-siloxyvinyl complexes Z-(CO){sub 5}Mn-C(OSiEt{sub 3})=CHR (R = H, CH{sub 3}, OCH{sub 3}). Carbonylation and protolytic cleavage of the latter generate pyruvoyl complexes (CO){sub 5}Mn-COCOR (R = CH{sub 3}, CH{sub 2}CH{sub 3}), formally the products of net ``double carbonylation`` sequences. Studies in progress are concerned with how manganese complexes as diverse as (CO){sub 5}Mn-Y [Y = C(O)R, R, BR - but not SiMe{sub 3} or Mn(CO){sub 5}] and ({eta}{sup 3}-C{sub 3}H{sub 5})Mn(CO){sub 2}L [but not CpMn(CO){sub 3} or CpMn(CO){sub 2}({eta}{sup 2}HSiR{sub 3})] function as efficient hydrosilation catalysts towards Cp(CO){sub 2}FeC(O)CH{sub 3}, for example. These reactions cleanly afford fully characterized {alpha}-siloxyethyl complexes Fp-CH(OSiR{sub 3})CH{sub 3} under conditions where typically Rh(1) hydrosilation catalysts are inactive. Several of these manganese complexes also catalytically hydrosilate organic esters, including lactones, to their ethers R-CH{sub 2}OR; these novel ester reductions occur quantitatively at room temperature and appear to be general in scope.

  18. Morphological and Phase Controlled Tungsten Based Nanoparticles: Synthesis and Characterization of Scheelites, Wolframites, and Oxides Nanomaterials

    PubMed Central

    Hernandez-Sanchez, Bernadette A.; Boyle, Timothy J.; Pratt, Harry D.; Rodriguez, Mark A.; Brewer, Luke N.; Dunphy, Darren R.

    2009-01-01

    For the first time tungsten based nanoparticles (WNPs) of scheelite (MWO4; M = Ca, Sr, Ba, Pb), wolframite (MWO4; M = Mn, Fe, Zn & (Mg0.60Mn0.17Fe0.26)WO4), and the oxide (WO3 and W18O49) were synthesized from solution precipitation (i.e.,trioctylamine or oleic acid) and solvothermal (i.e., benzyl alcohol) routes. The resultant WNPs were prepared directly from tungsten (VI) ethoxide (W(OCH2CH3)6, 1) and stoichiometeric mixtures of the following precursors: [Ca(N(SiMe3)2)2]2 (2), Pb(N(SiMe3)2)2 (3), Mn[(μ-Mes)2Mn(Mes)]2 (4), [Fe(μ-Mes)(Mes)]2 (5), Fe(CO)5 (6), H+[Ba2(μ3-ONep)(μ-ONep)2(ONep)(ONep)3(py)]−2 (7), H+[Sr5(μ4-O)(μ3-ONep)4(μ-ONep)4(ONep)(py)4]− (8), and [Zn(Et)(ONep)(py)]2 (9) where Mes = C6H2(CH3)3-2,4,6, ONep = OCH2CMe3, Et = CH2CH3, and py = pyridine. Through these routes, the WNP morphologies were found to be manipulated by the processing conditions, while precursor selection influenced the final phase observed. For the solution precipitation route, 1 yielded (5 × 100 nm) W18O49 rods while stochiometeric reactions between 1 and (2 – 9) generated homogenous sub 30 nm nano-dots, -diamonds, -rods, and -wires for the MWO4 systems. For the solvothermal route, 1 was found to produce wires of WO3 with aspect ratios of 20 while (1 & 2) formed 10 – 60 nm CaWO4 nanodots. Room temperature photoluminescent (PL) emission properties of select WNPs were also examined with fluorescence spectroscopy (λex = 320 nm). Broad PL emissions = 430, 420, 395, 420 nm were noted for 5 × 100 nm W18O49 rods, 5 × 15 nm, CaWO4 rods, 10 – 30 nm CaWO4 dots, and 10 nm BaWO4 diamonds, respectively. PMID:19911034

  19. HMT production and sublimation during thermal process of cometary organic analogs. Implications for its detection with the ROSETTA instruments

    NASA Astrophysics Data System (ADS)

    Briani, Giacomo; Fray, Nicolas; Cottin, Hervé; Benilan, Yves; Gazeau, Marie-Claire; Perrier, Sebastien

    2013-09-01

    One important component of refractory organic residues synthesized from interstellar/cometary ice analogues is hexamethylenetetramine (HMT, C6H12N4). However, HMT has never been observed in any astrophysical or planetary environment so far. We investigated thermal evolution of HMT above ambient temperature. The synthesis of the organic residue (ice deposition, photolysis and warming) as well as its heating to temperatures higher than 300 K are performed by means of the same experimental apparatus. The later also allows in situ continuous monitoring of both the solid organic residue (by FTIR spectrometry) and of the gas species (by mass spectrometry). Two different ice mixtures, composed of H2O:CH3OH:NH3 = 10:1:1 and H2O:CH3OH:NH3:CO2 = 10:1:1:2, were deposited and simultaneously photolyzed at 29 K. Warming these photolyzed ices up to 300 K allows the production of refractory organic residues. At 300 K the organic residues clearly show the presence of HMT, but also some difference, in particular in their oxygenated components. Different evolutions of the organic residues are observed for temperatures >300 K. We characterized the organic residue thermal evolution for temperatures up to 500 K. We observed that HMT is still produced at temperatures higher than 300 K. Production of solid HMT and sublimation are simultaneous. HMT observed in the solid phase could be only a minor fraction of the total HMT production, the major fraction being sublimated. The kinetics of the HMT thermal evolution strongly depends on the organic residue composition at 300 K and seems to depend on the exact nature of the oxygenated fraction of the organic residue. The maximum temperature at which solid HMT is observed is 450 K. As HMT forms only for temperatures greater than 280 K in laboratory conditions, it implies that the detection of solid HMT in extraterrestrial samples will provide a strong indication of their thermal history. Consequently, the search for HMT in both solid cometary

  20. A spectrophotometric and thermodynamic study of the sitting-atop complex formation from reaction between free base meso-tetraarylporphyrins and zirconyl nitrate in chloroform solution

    NASA Astrophysics Data System (ADS)

    Dehghani, Hossein; Mansournia, Mohammad Reza

    2009-10-01

    The sitting-atop complexation of meso-tetraarylporphyrins and its para-substituted derivatives (H 2t(4-X)pp, X:H, Br, Cl, CH(CH 3) 2, OCH 3, CH 3), as electron donors, with zirconyl, as an electron acceptor, have been investigated spectrophotometrically in chloroform. The mole ratio studies based on physicochemical techniques were employed clearly and revealed the formation of 1:1 sitting-atop complexes which was confirmed by UV-vis, 1H NMR and IR spectroscopic data. The value of the formation constant was estimated for each complex using a nonlinear optimization of the complex absorbance vs. mole ratio data by package KINFIT. The results showed that the stability of these complexes decreases with the temperature enhancement. Thermodynamic parameters, Δ G°, Δ H° and Δ S°, of the SAT complexes have been determined from the temperature dependence of formation constants by Van't Hoff equation. Also, the influence of the substituents of the aryl rings in H 2t(4-X)pp on the stability of the SAT complexes is discussed.

  1. Synthesis, crystal structure and fluorescence properties of terbium complexes with phenoxyacetic acid and 2,4,6-tris-(2-pyridyl)-s-triazine.

    PubMed

    Wang, Zhong-Xia; Wang, Ai-Ling; Wei, Xiao-Yan; Qu, Yan-Rong; Yue, Bin; Kang, Jie; Chu, Hai-Bin; Zhao, Yong-Liang

    2015-09-01

    Two complexes of Tb(3+), Gd(3+) /Tb(3+) and one heteronuclear crystal Gd(3+)/Tb(3+) with phenoxyacetic acid (HPOA) and 2,4,6-tris-(2-pyridyl)-s-triazine (TPTZ) have been synthesized. Elemental analysis, rare earth coordination titration, inductively coupled plasma atomic emission spectrometry (ICP-AES) and thermogravimetric analysis-differential scanning calorimetry (TG-DSC) analysis show that the two complexes are Tb2 (POA)6 (TPTZ)2 · 6H2O and TbGd(POA)6 (TPTZ)2 · 6H2O, respectively. The crystal structure of TbGd(POA)6 (TPTZ)2 · 2CH3OH was determined using single-crystal X-ray diffraction. The monocrystal belongs to the triclinic system with the P-1 space group. In particular, each metal ion is coordinately bonded to three nitrogen atoms of one TPTZ and seven oxygen atoms of three phenoxyacetic ions. Furthermore, there exist two coordinate forms between C6H5OCH2COO(-) and the metal ions in the crystal. One is a chelating bidentate, the other is chelating and bridge coordinating. Fluorescence determination shows that the two complexes possess strong fluorescence emissions. Furthermore, the fluorescence intensity of the Gd(3+)/Tb(3+) complex is much stronger than that of the undoped complex, which may result from a decrease in the concentration quench of Tb(3+) ions, and intramolecular energy transfer from the ligands coordinated with Gd(3+) ions to Tb(3+) ions.

  2. Defect Passivation of Organic–Inorganic Hybrid Perovskites by Diammonium Iodide toward High-Performance Photovoltaic Devices

    DOE PAGES

    Zhao, Ting; Chueh, Chu-Chen; Chen, Qi; ...

    2016-09-12

    The polycrystalline feature of solutionprocessed perovskite film and its ionic nature inevitably incur substantial crystallographic defects, especially at the film surface and the grain boundaries (GBs). Here, a simple defect passivation method was exploited by post-treating CH3NH3PbI3 (MAPbI3) film with a rationally selected diammonium iodide. The molecular structure of the used diammonium iodide was discovered to play a critical role in affecting the phase purity of treated MAPbI3. Both NH3I(CH2)4NH3I and NH3I(CH2)2O(CH2)2NH3I (EDBE) induce three-dimensional (3D) to two-dimensional (2D) perovskite phase transformation during the treatment while only NH3I(CH2)8NH3I (C8) successfully passivates perovskite surface and GBs without forming 2D perovskite becausemore » of the elevated activation energy arising from its unique anti-gauche isomerization. In conclusion, defect passivation of MAPbI3 was clearly confirmed by scanning Kelvin probe microscopy (SKPM) and time-resolved photoluminescence (TRPL) studies, which results in the reduced recombination loss in derived devices. Consequently, the perovskite solar cell with C8 passivation showed a much improved power conversion efficiency (PCE) of 17.60% compared to the control device PCE of 14.64%.« less

  3. An electro-optical and electron injection study of benzothiazole-based squaraine dyes as efficient dye-sensitized solar cell materials: a first principles study.

    PubMed

    Al-Fahdan, Najat Saeed; Asiri, Abdullah M; Irfan, Ahmad; Basaif, Salem A; El-Shishtawy, Reda M

    2014-12-01

    Squaraine dyes have attracted significant attention in many areas of daily life from biomedical imaging to semiconducting materials. Moreover, these dyes are used as photoactive materials in the field of solar cells. In the present study, we investigated the structural, electronic, photophysical, and charge transport properties of six benzothiazole-based squaraine dyes (Cis-SQ1-Cis-SQ3 and Trans-SQ1-Trans-SQ3). The effect of electron donating (-OCH3) and electron withdrawing (-COOH) groups was investigated intensively. Ground state geometry and frequency calculations were performed by applying density functional theory (DFT) at B3LYP/6-31G** level of theory. Absorption spectra were computed in chloroform at the time-dependent DFT/B3LYP/6-31G** level of theory. The driving force of electron injection (ΔG (inject)), relative driving force of electron injection (ΔG r (inject)), electronic coupling constants (|VRP|) and light harvesting efficiency (LHE) of all six compounds were calculated and compared with previously studied sensitizers. The ΔG (inject), ΔG r (inject) and |VRP| of all six compounds revealed that these sensitizers would be efficient dye-sensitized solar cell materials. Cis/Trans-SQ3 exhibited superior LHE as compared to other derivatives. The Cis/Trans geometric effect was studied and discussed with regard to electro-optical and charge transport properties.

  4. Vibrational and thermal characterisation of a new chiral drug under investigation for the therapy of congestive heart failure

    NASA Astrophysics Data System (ADS)

    Taddei, Paola; Torreggiani, Armida; Fini, Giancarlo

    2002-12-01

    Racemic (5,6-bis 2-methyl propanoic acid-1,2,3,4-tetrahydro-naphtalen-2-yl)-methylammonium chloride, CHF-1035, under clinical investigation for the treatment of congestive heart failure, was here characterised by Raman and IR spectroscopies coupled with thermal analysis (thermogravimetry and differential scanning calorimetry). These techniques proved suitable for investigating the presence of different polymorphic forms, their relative stability and interconversion tendency in relation to industrial manufacturing processes undergone by the drug (i.e. grinding, compression, heating). Crystallisation experiments were carried out and two different CHF-1035 polymorphic forms were identified. Both grinding and heating revealed to cause a polymorphic transformation of the drug crystal form. It was hypothesised that a change in molecular packing occurs in the drug by effect of both treatments. The possible sources of polymorphism were identified in the -OCOCH(CH 3) groups and in the saturated ring. The non-ground sample showed two endothermic transitions; since they are reversible and not due to desolvation processes the system is probably enantiotropic.

  5. IR/UV and UV/UV double-resonance study of guaiacol and eugenol dimers

    NASA Astrophysics Data System (ADS)

    Longarte, Asier; Redondo, Carolina; Fernández, José A.; Castaño, Fernando

    2005-04-01

    Guaiacol (2-methoxyphenol) and eugenol (4-allyl-2-methoxyphenol) molecules are biologically active phenol derivatives with an intramolecular -OH⋯OCH3 hydrogen bond (H bond). Pulsed supersonic expansions of mixtures of either of the two molecules with He yield weakly bound homodimers as well as other higher-order complexes. A number of complementary and powerful laser spectroscopic techniques, including UV-UV and IR-UV double resonances, have been employed to interrogate the species formed in the expansion in order to get information on their structures and spectroscopic properties. The interpretation of the spectra of eugenol dimer is complex and required a previous investigation on a similar but simpler molecule both to gain insight into the possible structures and support the conclusions. Guaiacol (2-methoxyphenol) has been used for that purpose. The combination of the broad laser study combined with ab initio calculations at the Becke 3 Lee-Yang-Parr/6-31+G(d) level has provided the isomer structures, the potential-energy wells, and shed light on the inter- and intramolecular interactions involved. Guaiacol homodimer has been shown to have a single isomer whereas eugenol dimer has at least two. The comparison between the computed geometries of the dimers, their respective energies, and the vibrational normal modes permits the identification of the spectra.

  6. Factors affecting production of compound A from the interaction of sevoflurane with Baralyme and soda lime.

    PubMed

    Fang, Z X; Kandel, L; Laster, M J; Ionescu, P; Eger, E I

    1996-04-01

    Various alkali (e.g., soda lime) convert sevoflurane to CF2=C(CF3)OCH2F, a vinyl ether called "Compound A, " whose toxicity raises concerns regarding the safe administration of sevoflurane via rebreathing circuits. In the present investigation, we measured the sevoflurane degradation and output of Compound A caused by standard (13% water) Baralyme brand absorbent and standard (15% water) soda lime, and Baralyme and soda lime having various water contents (including no water). We used a flow-through system, applying a gas flow rate relative to absorbent volume that roughly equaled the rate/volume found in clinical practice. Both absorbents, at similar water contents, temperatures, and sevoflurane concentrations, produced roughly equal concentrations of Compound A. Dry and nearly dry absorbents produced less Compound A early in exposure to sevoflurane, and more later, than standard absorbents. Increases in temperature and sevoflurane concentration increased output of Compound A. Both absorbents, especially when dry, also destroyed Compound A, the concentration exiting from absorbent resulting from a complex sum of production and destruction. We conclude that the variability of concentrations of Compound A found in clinical practice may be largely explained by the inflow rate used (i.e., by rebreathing), sevoflurane concentration, and absorbent temperature and dryness. The effect of dryness is complex, with fresh dry absorbent destroying Compound A as it is made, and with dry absorbent that has been exposed to sevoflurane for a period of time providing a sometimes unusually high output of Compound A.

  7. Crystal structure of bis-[μ-(4-meth-oxy-phen-yl)methane-thiol-ato-κ(2) S:S]bis-[chlorido-(η(6)-1-isopropyl-4-methyl-benzene)-ruthenium(II)] chloro-form disolvate.

    PubMed

    Stíbal, David; Süss-Fink, Georg; Therrien, Bruno

    2015-10-01

    The mol-ecular structure of the title complex, [Ru2(C8H9OS)2Cl2(C10H14)2]·2CHCl3 or (p-MeC6H4Pr (i) )2Ru2(SCH2-p-C6H5-OCH3)2Cl2·2CHCl3, shows inversion symmetry. The two symmetry-related Ru(II) atoms are bridged by two 4-meth-oxy-α-toluene-thiol-ato [(4-meth-oxy-phen-yl)methane-thiol-ato] units. One chlorido ligand and the p-cymene ligand complete the typical piano-stool coordination environment of the Ru(II) atom. In the crystal, the CH moiety of the chloro-form mol-ecule inter-acts with the chlorido ligand of the dinuclear complex, while one Cl atom of the solvent inter-acts more weakly with the methyl group of the bridging 4-meth-oxy-α-toluene-thiol-ato unit. This assembly leads to the formation of supra-molecular chains extending parallel to [021].

  8. (μ-Acetato-κ(2) O:O')[μ-2,6-bis-({bis-[(pyri-din-2-yl-κN)meth-yl]amino-κN}meth-yl)-4-methyl-phenolato-κ(2) O:O](metha-nol-κO)dizinc bis-(perchlorate).

    PubMed

    Das, Biswanath; Haukka, Matti; Nordlander, Ebbe

    2014-04-01

    The binuclear title complex, [Zn2(C33H33N6O)(CH3COO2)(CH3OH)](ClO4)2, was synthesized by the reaction between 2,6-bis-({[bis-(pyridin-2-yl)meth-yl]amino}-meth-yl)-4-methyl-phenol (H-BPMP), Zn(OAc)2 and NaClO4. The two Zn(II) ions are bridged by the phenolate O atom of the octadentate ligand and the acetate group. An additional methanol ligand is terminally coordinated to one of the Zn(II) ions, rendering the whole structure unsymmetric. Other symmetric dizinc complexes of BPMP have been reported. However, to the best of our knowledge, the present structure, in which the two Zn(II) ions are distinguishable by the number of coordinating ligands and the coordination geometries (octahedral and square-pyramidal), is unique. The dizinc complex is a dication, and two perchlorate anions balance the charge. The -OH group of the coordinating methanol solvent mol-ecule forms a hydrogen bond with a perchlorate counter-anion. One of the anions is disordered over two sets of sites with an occupancy ratio of 0.734 (2):0.266 (2).

  9. Formation of Graphene Oxide Nanocomposites from Carbon Dioxide Using Ammonia Borane.

    PubMed

    Zhang, Junshe; Zhao, Yu; Guan, Xudong; Stark, Ruth E; Akins, Daniel L; Lee, Jae W

    2012-01-17

    To efficiently recycle CO(2) to economically viable products such as liquid fuels and carbon nanomaterials, the reactivity of CO(2) is required to be fully understood. We have investigated the reaction of CO(2) with ammonia borane (AB), both molecules being able to function as either an acid or a base, to obtain more insights into the amphoteric activity of CO(2). In the present work, we demonstrate that CO(2) can be converted to graphene oxide (GO) using AB at moderate conditions. The conversion consists of two consecutive steps: CO(2) fixation (CO(2) pressure < 3 MPa and temperature < 100 °C) and graphenization (600-750 °C under 0.1 MPa of N(2)). The first step generates a solid compound that contains methoxy (OCH(3)), formate (HCOO) and aliphatic groups while the second graphenization is the pyrolysis of the solid compound to produce graphene oxide-boron oxide nanocomposites, which have been confirmed by micro-Raman spectroscopy, solid state (13)C and (11)B magic angle spinning-nuclear magnetic resonance (MAS-NMR), transmission electron microscopy (TEM), and atomic force microscopy (AFM). Our observations also show that the mass of solid product in CO(2) fixation process and raw graphene oxide nanocomposites is twice and 1.2 times that of AB initially charged, respectively. The formation of aliphatic groups without using metal-containing compounds at mild conditions is of great interest to the synthesis of various organic products starting from CO(2.).

  10. The pyrolytic degradation of wood-derived lignin from pulping process.

    PubMed

    Shen, D K; Gu, S; Luo, K H; Wang, S R; Fang, M X

    2010-08-01

    Lignin is a key component in the biomass with a complex polymeric structure of the phenyl-C(3) alkyl units. The kraft lignin from the wood pulping process is tested in TG-FTIR and Py-GC-MS. The samples are pyrolyzed in TGA coupled with FTIR from 30 to 900 degrees C at the heating rate of 20 and 40K/min. The evolution of phenolic compounds in the initial pyrolysis stage of lignin is determined by FTIR, while the second stage is mainly attributed to the production of the low molecular weight species. A bench-scale fast pyrolysis unit is employed to investigate the effect of temperature on the product yield and composition. It is found that the guaiacol-type and syringol-type compounds as the primary products of lignin pyrolysis are predominant in bio-oil, acting as the significant precursors for the formation of the derivatives such as the phenol-, cresol- and catechol-types. A series of free-radical chain-reactions, concerning the cracking of different side-chain structures and the methoxy groups on aromatic ring, are proposed to demonstrate the formation pathways for the typical compounds in bio-oil by closely relating lignin structure to the pyrolytic mechanisms. The methoxy group (-OCH(3)) is suggested to work as an important source for the formation of the small volatile species (CO, CO(2) and CH(4)) through the relevant free radical coupling reactions.

  11. Surface Chemistry of Trimethyl Phosphate on α-Fe2O3

    SciTech Connect

    Henderson, Michael A.

    2011-12-01

    The chemistry of trimethyl phosphate (TMP) was examined on the (012) crystallographic face of hematite (α-Fe2O3) using temperature programmed desorption (TPD), high resolution electron energy loss spectroscopy (HREELS), static secondary ion mass spectrometry (SSIMS) and Auger electron spectroscopy (AES). TMP binds to Fe3+ sites on the clean α-Fe2O3(012) surface through lone pairs on the P=O oxygen atom. A small portion of adsorbed TMP desorbs without decomposition, however, the majority of adsorbed TMP decomposes in a two step process on the clean surface. The first step, occurring at or below room temperature (RT), likely involves displacement or substitution of one –OCH3 group to form surface methoxy groups and adsorbed dimethyl phosphate (DMP). In the second step, DMP decomposes above 500 K to a 1:1 ratio of gaseous methanol and formaldehyde with phosphate left on the surface. Identification of these steps was confirmed using the chemistry of methanol on the clean surface. Coadsorption of TMP and water led to a small degree of hydrolysis between these two molecules in the multilayer, but no significant change in the chemistry on the surface. This work was supported by the US Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

  12. Phosphorus-nitrogen compounds. Part 20: Fully substituted spiro-cyclotriphosphazenic lariat (PNP-pivot) ether derivatives

    NASA Astrophysics Data System (ADS)

    Okumuş, Aytuğ; Bilge, Selen; Kılıç, Zeynel; Öztürk, Aslı; Hökelek, Tuncer; Yılmaz, Filiz

    2010-08-01

    The condensation reactions of partly substituted spiro-cyclotriphosphazenic lariat (PNP-pivot) ethers, N 3P 3[( o-NHPhO) 2R]Cl 4 [where R = -CH 2CH 2- ( 1) and -CH 2CH 2OCH 2CH 2- ( 2)] with morpholine and 1,4-dioxa-8-azaspiro[4,5]decane (DASD) produce fully substituted morpholino ( 3 and 4) and 1,4-dioxa-8-azaspiro[4,5]deca ( 5 and 6) phosphazenes. These are the new examples of the spiro-cyclophosphazenic lariat ether derivatives with N 2O x ( x = 2 and 3) donor type containing 11- and 14-membered macrocycles. The solid state structures of 3, 5 and 6 have been determined by X-ray diffraction techniques. Compound 3 has intermolecular N-H…O hydrogen bond, compound 5 has intra- and intermolecular N-H…O hydrogen bonds, while compound 6 has intramolecular N-H…O and O-H…N and intermolecular N-H…O and O-H…O hydrogen bonds. The correlations of the endocyclic ( α) and exocyclic ( α') NPN bond angles with δP spiro values are investigated. The structural investigations of 3- 6 have been verified by elemental analyses, MS, FTIR, 1H, 13C and 31P NMR, DEPT and HETCOR techniques.

  13. The reaction of primary aromatic amines with alkylene carbonates for the selective synthesis of bis-N-(2-hydroxy)alkylanilines: the catalytic effect of phosphonium-based ionic liquids.

    PubMed

    Selva, Maurizio; Fabris, Massimo; Lucchini, Vittorio; Perosa, Alvise; Noè, Marco

    2010-11-21

    At T≥ 140 °C, different primary aromatic amines (pX-C(6)H(4)NH(2); X = H, OCH(3), CH(3), Cl) react with both ethylene- and propylene-carbonates to yield a chemoselective N-alkylation process: bis-N-(2-hydroxyalkyl)anilines [pX-C(6)H(4)N(CH(2)CH(R)OH)(2); R = H, CH(3)] are the major products and the competitive formation of carbamates is substantially ruled out. At 140 °C, under solventless conditions, the model reaction of aniline with ethylene carbonate goes to completion by simply mixing stoichiometric amounts of the reagents. However, a class of phosphonium ionic liquids (PILs) such as tetraalkylphosphonium halides and tosylates turn out to be active organocatalysts for both aniline and other primary aromatic amines. A kinetic analysis monitored by (13)C NMR spectroscopy, shows that bromide exchanged PILs are the most efficient systems, able to impart a more than 8-fold acceleration to the reaction. The reactions of propylene carbonate take place at a higher temperature than those of ethylene carbonate, and only in the presence of PIL catalysts. A mechanism based on the Lewis acidity of tetraalkylphosphonium cations and the nucleophilicity of halide anions has been proposed to account for both the reaction chemoselectivity and the function of the catalysts.

  14. Pure Rotational Spectroscopy of Asymmetric Tops in the Undergraduate Classroom or Laboratory

    NASA Astrophysics Data System (ADS)

    Minei, A. J.; Cooke, S. A.

    2013-06-01

    Due to concerns of complexity, the asymmetric top, for which κ = {(2B - A - C) / (A - C)} ≠ ± 1, is feared, or at least avoided, by many instructors when explaining the rigid rotor. However, the spectral patterns formed by cold} asymmetric rigid rotors in the centimeter-wave} region of the electromagnetic spectrum can be easily identified. We will present some techniques for spectral analyses that we have successfully employed with undergraduate students who are either ``pre-quantum mechanics" or are currently enrolled in a chemical quantum mechanics class. The activities are simple, requiring the students to first locate repeating patterns and then apply simple algebraic expressions in order to determine all three rotational constants. The method will be illustrated using the spectra of 2,2,3,3-tetrafluoropropyl trifluoroacetate (CF_3C(=O)OCH_2CF_2CHF_2), (E)-1,3,3,3-tetrafluoropropene (CF_3CH=CHF), 1H,1H,2H-perfluorocyclobutane (CF_2CF_2CHFCH_2), and 2H-nonafluorobutane (CF_3CHFCF_2CF_3). The first two of these species have predominantly a-type spectra, the third has a predominantly b-type spectrum, the fourth has a predominantly c-type spectrum.

  15. Acaricidal activities of apiol and its derivatives from Petroselinum sativum seeds against Dermatophagoides pteronyssinus, Dermatophagoides farinae, and Tyrophagus putrescentiae.

    PubMed

    Song, Ha Yun; Yang, Ji Yeon; Suh, Joo Won; Lee, Hoi Seon

    2011-07-27

    The acaricidal effects of an active constituent derived from Petroselinum sativum seeds and its derivatives were determined using impregnated fabric disk bioassay against Dermatophagoides farinae , Dermatophagoides pteronyssinus , and Tyrophagus putrescentiae and compared with that of synthetic acaricide. The acaricidal constituent of P. sativum was isolated by various chromatographic techniques and identified as apiol. On the basis of LD(50) values against D. farinae and D. pteronyssinus, apiol (0.81 and 0.94 μg/cm(2)) was 12.4 and 10.2 times more toxic than benzyl benzoate (10.0 and 9.58 μg/cm(2)), respectively. In acaricidal studies of apiol derivatives, 3,4-methylenedioxybenzonitrile (0.04, 0.03, and 0.59 μg/cm(2)) was 250, 319, and 20.7 times more toxic than benzyl benzoate (10.0, 9.58, and 12.2 μg/cm(2)) against D. farinae, D. pteronyssinus, and T. putrescentiae. In structure-activity relationships, the acaricidal activities of apiol derivatives could be related to allyl (-C(3)H(5)) and methoxy (-OCH(3)) functional groups. Furthermore, apiol and its derivatives could be useful for natural acaricides against these three mite species.

  16. Pancreatic Stenting Reduces Post-ERCP Pancreatitis and Biliary Sepsis in High-Risk Patients: A Randomized, Controlled Study

    PubMed Central

    Wu, Hai-En; Li, Qi-Xiang; Wang, Wei; Ou, Wei-Lin; Xia, Harry Hua-Xiang

    2016-01-01

    Background. Endoscopic retrograde cholangiopancreatography (ERCP) is an established treatment modality for bile duct disorders, but patients have a risk of post-ERCP pancreatitis (PEP) and biliary sepsis. Aim. To evaluate the effectiveness and safety of pancreatic stent for prophylaxis of PEP and biliary sepsis in high-risk patients with complicating common bile duct (CBD) disorders. Methods. Two hundred and six patients with complicating confirmed or suspected CBD disorders were randomly assigned to receive ERCP with pancreatic stenting (experimental group) or without stenting (control group). Primary outcome measure was frequency of PEP, and secondary outcome measures included operative time, blood loss, postoperative recovery times, and other ERCP-associated morbidities. Results. Baseline age, sex, CBD etiology, concomitant medical/surgical conditions, cannulation difficulty, and ERCP success were comparable between the two groups (all P > 0.05). Compared to the control group, the experimental group had a significantly lower frequency of PEP (7.7% versus 17.7%, P < 0.05) and positive bile microbial culture (40.4% versus 62.7%, P < 0.05). However, the two groups were similar in operative time, blood loss, postoperative recovery times, and other ERCP-associated morbidities (all P > 0.05). Conclusions. Pancreatic stenting can reduce the occurrence of PEP and biliary sepsis in high-risk patients with complicating CBD disorders but does not increase other ERCP-associated morbidities. This trial is registered with the Chinese Clinical Trial Registry (registration identifier ChiCTR-OCH-14005134). PMID:27057161

  17. Corrosion inhibition of mild steel in 1M HCl by D-glucose derivatives of dihydropyrido [2,3-d:6,5-d′] dipyrimidine-2, 4, 6, 8(1H,3H, 5H,7H)-tetraone

    PubMed Central

    Verma, Chandrabhan; Quraishi, M. A.; Kluza, K.; Makowska-Janusik, M.; Olasunkanmi, Lukman O.; Ebenso, Eno E.

    2017-01-01

    D-glucose derivatives of dihydropyrido-[2,3-d:6,5-d′]-dipyrimidine-2, 4, 6, 8(1H,3H, 5H,7H)-tetraone (GPHs) have been synthesized and investigated as corrosion inhibitors for mild steel in 1M HCl solution using gravimetric, electrochemical, surface, quantum chemical calculations and Monte Carlo simulations methods. The order of inhibition efficiencies is GPH-3 > GPH-2 > GPH-1. The results further showed that the inhibitor molecules with electron releasing (-OH, -OCH3) substituents exhibit higher efficiency than the parent molecule without any substituents. Polarization study suggests that the studied compounds are mixed-type but exhibited predominantly cathodic inhibitive effect. The adsorption of these compounds on mild steel surface obeyed the Langmuir adsorption isotherm. SEM, EDX and AFM analyses were used to confirm the inhibitive actions of the molecules on mild steel surface. Quantum chemical (QC) calculations and Monte Carlo (MC) simulations studies were undertaken to further corroborate the experimental results. PMID:28317849

  18. Purification and properties of methyl formate synthase, a mitochondrial alcohol dehydrogenase, participating in formaldehyde oxidation in methylotrophic yeasts.

    PubMed Central

    Murdanoto, A P; Sakai, Y; Konishi, T; Yasuda, F; Tani, Y; Kato, N

    1997-01-01

    Methyl formate synthase, which catalyzes methyl formate formation during the growth of methylotrophic yeasts, was purified to homogeneity from methanol-grown Candida boidinii and Pichia methanolica cells. Both purified enzymes were tetrameric, with identical subunits with molecular masses of 42 to 45 kDa, containing two atoms of zinc per subunit. The enzymes catalyze NAD(+)-linked dehydrogenation of the hydroxyl group of the hemiacetal adduct [CH2(OH)OCH3] of methanol and formaldehyde, leading to the formation of a stoichiometric amount of methyl formate. Although neither methanol nor formaldehyde alone acted as a substrate for the enzymes, they showed simple NAD(+)-linked alcohol dehydrogenase activity toward aliphatic long-chain alcohols such as octanol, showing that they belong to the class III alcohol dehydrogenase family. The methyl formate synthase activity of C. boidinii was found in the mitochondrial fraction in subcellular fractionation experiments, suggesting that methyl formate synthase is a homolog of Saccharomyces cerevisiae Adh3p. These results indicate that formaldehyde could be oxidized in a glutathione-independent manner by methyl formate synthase in methylotrophic yeasts. The significance of methyl formate synthase in both formaldehyde resistance and energy metabolism is also discussed. PMID:9143107

  19. Antigen Specificity of Type I NKT Cells Is Governed by TCR β-Chain Diversity.

    PubMed

    Cameron, Garth; Pellicci, Daniel G; Uldrich, Adam P; Besra, Gurdyal S; Illarionov, Petr; Williams, Spencer J; La Gruta, Nicole L; Rossjohn, Jamie; Godfrey, Dale I

    2015-11-15

    NKT cells recognize lipid-based Ags presented by CD1d. Type I NKT cells are often referred to as invariant owing to their mostly invariant TCR α-chain usage (Vα14-Jα18 in mice, Vα24-Jα18 in humans). However, these cells have diverse TCR β-chains, including Vβ8, Vβ7, and Vβ2 in mice and Vβ11 in humans, joined to a range of TCR Dβ and Jβ genes. In this study, we demonstrate that TCR β-chain composition can dramatically influence lipid Ag recognition in an Ag-dependent manner. Namely, the glycolipids α-glucosylceramide and isoglobotrihexosylceramide were preferentially recognized by Vβ7(+) NKT cells from mice, whereas the α-galactosylceramide analog OCH, with a truncated sphingosine chain, was preferentially recognized by Vβ8(+) NKT cells from mice. We show that the influence of the TCR β-chain is due to a combination of Vβ-, Jβ-, and CDR3β-encoded residues and that these TCRs can recapitulate the selective Ag reactivity in TCR-transduced cell lines. Similar observations were made with human NKT cells where different CDR3β-encoded residues determined Ag preference. These findings indicate that NKT TCR β-chain diversity results in differential and nonhierarchical Ag recognition by these cells, which implies that some Ags can preferentially activate type I NKT cell subsets.

  20. Molecular conductance at finite voltage: bias driven evolution of Kohn-Sham-orbitals

    NASA Astrophysics Data System (ADS)

    Koentopp, Max; Evers, Ferdinand; Burke, Kieron

    2006-03-01

    Ground state density functional theory calculations yield the exact electron density if the exact exchange-correlation functional is employed. The evolution of the equilibrium density with parametric changes in the Hamiltonian, e.g. realized by a change in the electrostatic potential, can provide crucial information about transport properties, like the Coulomb blockade. To test our ideas, we perform model calculations using the quantum chemistry package TURBOMOLE for a diode molecule, which exhibits the structure of a double quantum dot and has been investigated experimentally [1]. In particular, we explain the origin of the characteristic peak structure in the differential conductance. Our results are consistent with the interpretation that the stepwise increase of the conductance occurs when the number of occupied levels of one of the dots, that have an energy above the lowest unoccupied level of the other dot, increases by one.[1] M. Elbing, R. Ochs, M. Koentopp, M. Fischer, C. von Hänisch, F. Weigend, F. Evers, H. Weber, M. Mayor, Proc. Nat. Acad. Sci. USA 102, 8815 (2005).