Sample records for bibenzyl

  1. Antioxidant Bibenzyl Derivatives from Notholaena nivea Desv.

    Paola Montoro


    Full Text Available Four new bibenzyl derivatives were isolated, together with other known bibenzyls, by bioassay-guided fractionation of a CHCl3-MeOH extract of Notholaena nivea Desv. (Pteridaceae aerial parts. The structures were elucidated by NMR, ESIMS and other spectral analyses. Their antioxidative effects towards superoxide, lipidic peroxidation and the 2,2'-azino-bis-3-ethilbenzothiazoline-6-sulfonic acid (ABTS radical were assayed. Results showed that the compound 3,12-dihydroxy-5-methoxybibenzyl (6 is the most active compound in the ABTS free-radical scavenging test, while in the coupled oxidation of β-carotene and linoleic acid assay the compound 5,12-dihydroxy-3-methoxydibenzyl-6-carboxylic acid (1 exerted the highest activity after 1h. A superoxide anion enzymatic test was also carried out and the results were confirmed by an inhibition of xanthine oxidase activity assay. The putative protective role played by compounds 1 and 6 on the injurious effects of reactive oxygen metabolites on the intestinal epithelium, using a Caco-2 human cell line, was investigated. H2O2-induced alterations were prevented by preincubating the cells with compounds 1 and 6.

  2. Laser-induced dry-fabrication of bibenzyl molecular layers on the silicon surface

    Graphical abstract: Schematic illustration of photoinduced polymerization of 4-bromostyrene molecules on the Si(1 1 1)-(7 × 7) surface. - Highlights: • Laser-induced fabrication of molecular layer. • XPS and HREELS experimental evidence for the reaction. • DFT explanation of photochemical reaction. - Abstract: The covalently attached organic monolayer has great effects on the structures of the organic semiconductor thin films and their electronic transport properties in the fabrication of molecular electronic devices. A laser-induced dry-fabrication method has been developed to form bibenzyl-like molecular layers by photoinduced reaction of 4-bromostyrene molecules on silicon surface in the vacuum environment. The radical site produced via the C–Br bond cleavage concurrently reacts with the C=C vinyl group of the physisorbed 4-bromostyrene molecule above to form the –CH2–CHBr– covalent linkage. X-ray photoelectron spectroscopy (XPS) and high-resolution electron energy loss spectroscopy (HREELS) experimental results and density functional theory (DFT) calculations confirm the formation of covalently bonded bibenzyl-like (Phi–CH2–CHBr–Phi) molecular layers on the silicon surface

  3. Minimum structural requirements for cell membrane leakage-mediated anti-MRSA activity of macrocyclic bis(bibenzyl)s.

    Fujii, Kana; Morita, Daichi; Onoda, Kenji; Kuroda, Teruo; Miyachi, Hiroyuki


    Macrocyclic bis(bibenzyl)-type phenolic natural products, found exclusively in bryophytes, exhibit potent antibacterial activity towards methicillin-resistant Staphylococcus aureus (anti-MRSA activity). Here, in order to identify the minimum essential structure for cell membrane leakage-mediated anti-MRSA activity of these compounds, we synthesized acyclic fragment structures and evaluated their anti-MRSA activity. The activities of all of the acyclic fragments tested exhibited similar characteristics to those of the macrocycles, i.e., anti-MRSA bactericidal activity, an enhancing effect on influx and efflux of ethidium bromide (EtBr: fluorescent DNA-binder) in Staphylococcus aureus cells, and bactericidal activity towards a Staphylococcus aureus strain resistant to 2-phenoxyphenol (4). The latter result suggests that they have a different mechanism of action from 4, which is a FabI inhibitor previously proposed to be the minimum active fragment of riccardin-type macrocycles. Thus, cyclic structure is not a necessary condition for cell membrane leakage-mediated anti-MRSA activity of macrocyclic bis(bibenzyl)s. PMID:26995530

  4. Bis(bibenzyls) from liverworts inhibit lipopolysaccharide-induced inducible NOS in RAW 264.7 cells: a study of structure-activity relationships and molecular mechanism.

    Harinantenaina, Liva; Quang, Dang Ngoc; Takeshi, Nishizawa; Hashimoto, Toshihiro; Kohchi, Chie; Soma, Gen-Ichiro; Asakawa, Yoshinori


    The inhibition of lipopolysaccharide-induced NOS by 19 bis(bibenzyls) isolated from liverworts in RAW 264.7 macrophages was evaluated. The presence of phenolic hydroxyls and saturation at 7,8 and/or 7'/8' are required for inhibition of NO production. Among the compounds tested, marchantin A was the most potent, and its inhibitory activity was consistent with the inhibition of LPS-induced iNOS mRNA. PMID:16378374

  5. Effect of plagiochin E, an antifungal macrocyclic bis(bibenzyl), on cell wall chitin synthesis in Candida albicans

    Xiu-zhen WU; Ai-xia CHENG; Ling-mei SUN; Hong-xiang LOU


    Aim: To investigate the effect of plagiochin E (PLE), an antifungal macrocyclic bis(bibenzyl) isolated from liverwort Marchantia polymorpha L, on cell wall chitin synthesis in Candida albicans. Methods: The effect of PLE on chitin synthesis in Candida albicans was investigated at the cellular and molecular lev-els. First, the ultrastructural changes were observed under transmission electron microscopy (TEM). Second, the effects of PLE on chitin synthetase (Chs) activi-ties in vitro were assayed using 6-O-dansyl-N-acetylglucosamine as a fluorescent substrate, and its effect on chitin synthesis in situ was assayed by spheroplast regeneration. Finally, real-time RT-PCR was performed to assay its effect on the expression of Chs genes (CHS). Results: Observation under TEM showed that the structure of the cell wall in Candida albicans was seriously damaged, which suggested that the antifungal activity of PLE was associated with its effect on the cell wail. Enzymatic assays and spheroplast regeneration showed that PLE inhibited chitin synthesis in vitro and in situ. The results of the PCR showed that PLE significantly downregulated the expression of CHS1, and upregulated the expression of CHS2 and CHS3. Because different Chs is regulated at different stages of transcription and post-translation, the downregulation of CHS1 would decrease the level of Chs 1 and inhibit its activity, and the inhibitory effects of PLE on Chs2 and Chs3 would be at the post-translational level or by the inhibi-tion on the enzyme-active center. Conclusion: These results indicate that the antifungal activity of PLE would be attributed to its inhibitory effect on cell wall chitin synthesis in Candida albicans.

  6. Electrochemistry and catalytic properties of amphiphilic vitamin B12 derivatives in nonaqueous media.

    Giedyk, M; Shimakoshi, H; Goliszewska, K; Gryko, D; Hisaeda, Y


    The reduction pathway of cobalester (CN)Cble, an amphiphilic vitamin B12 derivative, was investigated in organic solvents under electrochemical conditions and compared with mono- and dicyanocobyrinates. The redox characteristics were determined using cyclic voltammetry and spectroelectrochemical methods. The presence of a nucleotide moiety in B12-derivative impedes the in situ formation of dicyano-species thus facilitating the (CN)Co(iii) to Co(i) reduction. The (CN)Cble shows stepwise reduction to Co(i) via (CN)Co(ii). The reduction of (CN)Co(ii)/Co(i) was found to depend on cyanide-solvent exchange equilibrium with weakly coordinating solvents and bulky peripheral chains promoting intact (CN)Co(ii) species existence. The studied complexes were also utilized as catalysts in bulk electrolysis of benzyl bromide affording bibenzyl in very good yield. PMID:26974051

  7. Neutron detection with single crystal organic scintillators

    Zaitseva, N; Newby, J; Hamel, S; Carman, L; Faust, M; Lordi, V; Cherepy, N; Stoeffl, W; Payne, S


    Detection of high-energy neutrons in the presence of gamma radiation background utilizes pulse-shape discrimination (PSD) phenomena in organics studied previously only with limited number of materials, mostly liquid scintillators and single crystal stilbene. The current paper presents the results obtained with broader varieties of luminescent organic single crystals. The studies involve experimental tools of crystal growth and material characterization in combination with the advanced computer modeling, with the final goal of better understanding the relevance between the nature of the organic materials and their PSD properties. Special consideration is given to the factors that may diminish or even completely obscure the PSD properties in scintillating crystals. Among such factors are molecular and crystallographic structures that determine exchange coupling and exciton mobility in organic materials and the impurity effect discussed on the examples of trans-stilbene, bibenzyl, 9,10-diphenylanthracene and diphenylacetylene.

  8. Thermal decomposition of allylbenzene ozonide

    Ewing, J.C.; Church, D.F.; Pryor, W.A. (Louisiana State Univ., Baton Rouge (USA))


    Thermal decomposition of allylbenzene ozonide (ABO) at 98{degree}C in the liquid phase yields toluene, bibenzyl, phenylacetaldehyde, formic acid, and (benzyloxy)methyl formate as major products; benzyl chloride is formed when chlorinated solvents are employed. These products, as well as benzyl formate, are formed when ABO is decomposed at 37{degree}C. When the decomposition of ABO is carried out in the presence of 1-butanethiol, the product distribution changes: yields of toluene increase, no bibenzyl is formed, and decreases in yields of (benzyloxy)methyl formate, phenylacetladehyde, and benzyl chloride are observed. The decomposition of 1-octene ozonide (OTO) also was studied for comparison. The activation parameters for both ABO and OTO are similar (28.2 kcal/mol, log A = 13.6 and 26.6 kcal/mol, log A = 12.5, respectively); these data suggest that ozonides decompose by homolysis of the O-O bond, rather than by an alternative synchronous two-bond scission process. When ABO is decomposed at 37{degree}C in the presence of the spin traps 5,5-dimethyl-1-pyrroline N-oxide (DMPO) or 3,3,5,5-tetramethyl-1-pyrroline N-oxide (M{sub 4}PO), ESR signals are observed that are consistent with the trapping of benzyl and other carbon- and oxygen-centered radicals. A mechanism for the thermal decomposition of ABO that involves peroxide bond homolysis and subsequent {beta}-scission is proposed. Thus, Criegee ozonides decompose to give free radicals at quite modest temperatures.

  9. Polycyclic aromatic hydrocarbon (PAH) formation from benzyl radicals: a reaction kinetics study.

    Sinha, Sourab; Raj, Abhijeet


    The role of resonantly stabilized radicals such as propargyl, cyclopentadienyl and benzyl in the formation of aromatic hydrocarbons such as benzene and naphthalene in the high temperature environments has been long known. In this work, the possibility of benzyl recombination to form three-ring aromatics, phenanthrene and anthracene, is explored. A reaction mechanism for it is developed, where reaction energetics are calculated using density functional theory (B3LYP functional with 6-311++G(d,p) basis set) and CBS-QB3, while temperature-dependent reaction kinetics are evaluated using transition state theory. The mechanism begins with barrierless formation of bibenzyl from two benzyl radicals with the release of 283.2 kJ mol(-1) of reaction energy. The further reactions involve H-abstraction by a H atom, H-desorption, H-migration, and ring closure to gain aromaticity. Through mechanism and rate of production analyses, the important reactions leading to phenanthrene and anthracene formation are determined. Phenanthrene is found to be the major product at high temperatures. Premixed laminar flame simulations are carried out by including the proposed reactions for phenanthrene formation from benzyl radicals and compared to experimentally observed species profiles to understand their effects on species concentrations. PMID:26923612

  10. Bond cleavage reactions of the bridge structure in coal in the presence of hydrogen donating compounds; Suiso kyoyosei kagobutsu sonzaika deno sekitanchu no kakyo kozo no kairetsu hanno

    Bando, N.; Kidena, K.; Murata, S.; Nomura, M. [Osaka University, Osaka (Japan). Faculty of Engineering


    In this paper, bond cleavage reactions are discussed in relation to the softening and solubilization of coal. Were used 9,10-dihydroanthracene (DHA) and 9,10-dihydrophenanthrene (DHP) as models of hydrogen donating compounds in coal, and bibenzyl, 1,2-diethane, benzylphenylether, and 1,5-dibenzylnaphthalene were used as models of bridge structure compounds. They were compared mutually, as to reactivity of coal against DHA and DHP. For the homolytic cleavage of bridges, DHA with excellent radical supplement performance provided excellent hydrogen donating performance. While, for the ipso-position cleavage of bridges, it was found that DHP can act as an effective hydrogen donor. For the reaction between coal and hydrogenated aromatic compounds, cleavage of relatively weak bonds, such as ether linkage and dimethylene linkage, occurred at about 380{degree}C, and hydrogen from DHA or DHP was consumed. On the other hand, the results suggested that the cleavage reaction at ipso-position affected by hydrogen donating solvent is also important at temperature range around 420{degree}C. 2 refs., 3 figs., 1 tab.

  11. Synthesis and characterization of Fe colloid catalysts in inverse micelle solutions

    Martino, A.; Stoker, M.; Hicks, M. [Sandia National Lab., Alburquerque, NM (United States)] [and others


    Surfactant molecules, possessing a hydrophilic head group and a hydrophobic tail group, aggregate in various solvents to form structured solutions. In two component mixtures of surfactant and organic solvents (e.g., toluene and alkanes), surfactants aggregate to form inverse micelles. Here, the hydrophilic head groups shield themselves by forming a polar core, and the hydrophobic tails groups are free to move about in the surrounding oleic phase. The formation of Fe clusters in inverse miscelles was studied.Iron salts are solubilized within the polar interior of inverse micelles, and the addition of the reducing agent LiBH{sub 4} initiates a chemical reduction to produce monodisperse, nanometer sized Fe based particles. The reaction sequence is sustained by material exchange between inverse micelles. The surfactant interface provides a spatial constraint on the reaction volume, and reactions carried out in these micro-heterogeneous solutions produce colloidal sized particles (10-100{Angstrom}) stabilized in solution against flocculation of surfactant. The clusters were stabilized with respect to size with transmission electron microscopy (TEM) and with respect to chemical composition with Mossbauer spectroscopy, electron diffraction, and x-ray photoelectron spectroscopy (XPS). In addition, these iron based clusters were tested for catalytic activity in a model hydrogenolysis reaction. The hydrogenolysis of naphthyl bibenzyl methane was used as a model for coal pyrolysis.

  12. Novel bimetallic dispersed catalysts for temperature-programmed coal liquefaction

    Chunshan, Song; Kirby, S.; Schmidt, E. [Pennsylvania State Univ., University Park, PA (United States)] [and others


    The objective of this project is to explore bimetallic dispersed catalysts for more efficient coal liquefaction. Coal liquefaction involves cleavage of methylene, dimethylene and ether bridges connecting various aromatic units and the reactions of various oxygen functional groups. This paper describes recent results on (1) hydrodeoxygenation of O-containing polycyclic model compounds using novel organometallic catalyst precursors; and (2) activity and selectivity of dispersed Fe catalysts from organometallic and inorganic precursors for hydrocracking of 4-(1-naphthylmethyl) bibenzyl. The results showed that some iron containing catalysts have higher activity in the sulfur-free form, contrary to conventional wisdom. Adding sulfur to Fe precursors with Cp-ligands decreased the activity of the resulting catalyst. This is in distinct contrast to the cases with iron pentacarbonyl and superfine Fe{sub 2}O{sub 3}, where S addition increased their catalytic activity substantially. A positive correlation between sulfur addition and increased activity can be seen, but a reversed trend between Fe cluster size and hydrocracking conversion could be observed, for carbonyl-type Fe precursors. It is apparent that the activity and selectivity of Fe catalysts for NMBB conversion depends strongly on both the type of ligand environment, the oxidation state and the number of intermetal bonds in the molecular precursor.

  13. 铁皮石斛有效成分与功效研究进展%Advances in the of Constituents and Pharmacological Effects of Dendrobium candidum Wall. ex. Lind.

    廖俊杰; 李文静; 李进进; 李桂锋; 姚焕霞


    铁皮石斛是具有滋阴补益功效的名贵药材, 在治疗和日常保健中应用广泛. 本文主要对铁皮石斛多糖、 生物碱、 菲类、 联苄类、 酚酸类等有效化学成分和抗肿瘤、 提高免疫、 抗衰老、 降血糖等药理作用进行综述, 为铁皮石斛有效化学成分研究及开发药用价值的天然产物提供理论基础.%Dendrobium candidum Wall. ex. Lind. is a valuable medicinal plant and is widely used in treatment and daily health care. Chemical constituents in polysaccharides, alkaloids, phenanthrenes, bibenzyls and phenolic acids are reviewed, and pharmacological effects for improving immune functioning, anti-tumor, anti-aging and lowering blood glucose are integrated. A scientific and theoretical foundation for studying constituents and biological activities of Dendrobium candidum Wall. ex. Lind. , and for further developing medicinal value of natural products is provided.

  14. Superacid Catalyzed Coal Conversion Chemistry. 1st and 2nd Quarterly Technical Progress Reports, September 1, 1983-March 30, 1984.

    Olah, G. A.


    In our laboratories we have previously developed a mild coal conversion process. This involves the use of a superacid system consisting of HF and BF{sub 3} in presence of hydrogen and/or a hydrogen donor solvent. In order to understand the chemistry involved in the process of depolymerization of coal by the HF:BF{sub 3}:H{sub 2} system we are carrying out a systematic study of a number of coal model compounds. The model compounds selected for present study have two benzene rings connected with various bridging units such as alkylidene, ether, sulfide etc. From studies so far carried out it appears that high pyridine extractibilities achieved by treating coal at temperature below 100 degrees C results from the cleavage of bridges such as present in bibenzyl, diphenyl methane, dibenzyl ether, dibenzyl sulfide etc. On the other hand the increased cyclohexane extractibility and distillability observed at relatively higher temperatures and hydrogen pressures reflects the hydrogenation and cleavage of the aromatic backbone in coal structure similar to what is seen in the conversion of model compounds such as biphenyl, diphenyl ether, diphenyl sulfide, anthracene, etc.

  15. Bisbibenzyls, a new type of antifungal agent, inhibit morphogenesis switch and biofilm formation through upregulation of DPP3 in Candida albicans.

    Li Zhang

    Full Text Available The yeast-to-hypha transition plays a crucial role in the pathogenesis of C. albicans. Farnesol, a quorum sensing molecule (QSM secreted by the fungal itself, could prevent the formation of hyphae and subsequently lead to the defect of biofilm formation. The DPP3, encoding phosphatase, is a key gene in regulating farnesol synthesis. In this study, we screened 24 bisbibenzyls and 2 bibenzyls that were isolated from bryophytes or chemically synthesized by using CLSI method for antifungal effect. Seven bisbibenzyls were found to have antifungal effects with IC(80 less than 32 µg/ml, and among them, plagiochin F, isoriccardin C and BS-34 were found to inhibit the hyphae and biofilm formation of C. albicans in a dose-dependent manner. To uncover the underlying relationship between morphogenesis switch and QSM formation, we measured the farnesol production by HPLC-MS and quantified Dpp3 expression by detecting the fluorescent intensity of green fluorescent protein tagged strain using Confocal Laser Scanning microscopy and Multifunction Microplate Reader. The DPP3 transcripts were determined by real-time PCR. The data indicated that the bisbibenzyls exerted antifungal effects through stimulating the synthesis of farnesol via upregulation of Dpp3, suggesting a potential antifungal application of bisbibenzyls. In addition, our assay provides a novel, visual and convenient method to measure active compounds against morphogenesis switch.

  16. The synthesis and characterization of iron colloid catalysts in inverse micelle solutions

    Martino, Anthony; Sault, Allen G.; Kawola, Jeffrey S. [Fuel Science Department, Sandia National Laboratories Albuquerque, NM (United States); Stoker, Matthew; Hicks, Michael; Bartholomew, Calvin H. [Department of Chemical Engineering, Brigham Young University Provo, UT (United States)


    We have studied the synthesis and characterization of Fe based nanometer sized clusters formed in inverse micelle solutions. Inverse micelles provide a colloidal sized reaction template in an oleic solvent. Metal salts are solubilized within the interior of inverse micelles, and the addition of a reducing agent initiates nucleation and growth to produce the clusters. Surfactant acts to stabilize the particles. TEM shows that the average particle size is less than 3nm in diameter. The reduction reaction of iron salts with LiBH{sub 4} in inverse micelle solutions results in the formation of FeB, Fe{sup 2+}BO{sub x} (i.e. pyroborate), and {alpha}-Fe as determined by Mossbauer spectroscopy, electron diffraction, and X-ray photoelectron spectroscopy (XPS). Oxidation after exposure to air leads to the conversion of the FeB to {alpha}-Fe then to an undetermined Fe{sup 2+} phase and then finally to Fe{sub 3}O{sub 4}. Iron based metals are of interest as active, selective catalysts for a number of hydrogenation reactions including methanation and Fischer-Tropsch synthesis. We report catalytic results of iron clusters in the hydrogenolysis of naphthyl bibenzyl methane (NBM), a model reaction for coal liquefaction. The role of surfactant in the reaction mechanism is determined

  17. The effect of plagiochin E alone and in combination with fluconazole on the ergosterol biosynthesis of Candida albicans.

    Sun, Ling Mei; Lv, Bei Bei; Cheng, Ai Xia; Wu, Xiu Zhen; Lou, Hong Xiang


    Plagiochin E (PLE), a macrocyclic bis(bibenzyl) isolated from the liverwort Marchantia polymorpha, has been reported to have antifungal activity and resistance reversal effects on Candida albicans. In order to understand the underlying mechanisms, we studied the effects of PLE alone and in combination with fluconazole (FLC) on the ergosterol biosynthetic pathway against both FLC-sensitive and FLC-resistant strains by analyzing the sterol content and the ergosterol pathway gene (ERG) expression. Relative quantitative analysis of different ergosterol precursors was carried out by employing the hyphenated technique of gas chromatography-high resolution mass spectrometry (GC-HR-MS). We observed that for FLC-resistant strain PLE itself can cause the accumulation of lanosterol and the decrease of 14alpha-methylfecosterol. When it combined with FLC, a significant decrease was observed in ergosterol formation and corresponding accumulation of 14alpha-methylated sterols was also found. Real-time reverse transcription-polymerase chain reaction (RT-PCR) analysis revealed that the transcription level of ERG11 was decreased in FLC-resistant strain when exposed to PLE alone or PLE plus FLC. These results suggest that PLE potentiates FLC antifungal activity by interfering with the FLC-targeted ergosterol biosynthesis pathway. PMID:19122277

  18. Novel bimetallic dispersed catalysts for temperature-programmed coal liquefaction. Final report

    Chunshan Song; Schobert, H.H.; Parfitt, D.P. [and others


    Development of new catalysts is a promising approach to more efficient coal liquefaction. It has been recognized that dispersed catalysts are superior to supported catalysts for primary liquefaction of coals, because the control of initial coal dissolution or depolymerization requires intimate contact between the catalyst and coal. This research is a fundamental and exploratory study on catalytic coal liquefaction, with the emphasis on exploring novel bimetallic dispersed catalysts for coal liquefaction and the effectiveness of temperature-programmed liquefaction using dispersed catalysts. The primary objective of this research was to explore novel bimetallic dispersed catalysts from organometallic molecular precursors, that could be used in low concentrations but exhibit relatively high activity for efficient hydroliquefaction of coals under temperature-programmed conditions. We have synthesized and tested various catalyst precursors in liquefaction of subbituminous and bituminous coals and in model compound studies to examine how do the composition and structure of the catalytic precursors affect their effectiveness for coal liquefaction under different reaction conditions, and how do these factors affect their catalytic functions for hydrogenation of polyaromatic hydrocarbons, for cleavage of C-C bonds in polycyclic systems such as 4-(1-naphthylmethyl)bibenzyl, for hydrogenolysis of C-O bond such as that in dinaphthylether, for hydrodeoxygenation of phenolic compounds and other oxygen-containing compounds such as xanthene, and for hydrodesulfurization of polycyclic sulfur compounds such as dibenzothiophene. The novel bimetallic and monometallic precursors synthesized and tested in this project include various Mo- and Fe-based compounds.

  19. In silico analysis of compounds from Stemona tuberosa as an inhibitor for N1 neuraminidase of H5N1 avian virus

    Abhilash Manohar


    Full Text Available The worldwide spread of H5N1 avian influenza has raised concerns that this virus might acquire the ability to pass readily among humans and cause a pandemic.Two anti-influenza drugs currently being used to treat the infected patients are oseltamivir (Tamiflu and zanamivir (Relenza, both of which target the neuraminidase enzyme of the virus. Reports of the emergence of drug resistance has made the development of new anti-influenza molecules a priority. Various compounds present in Stemona tuberosa a plant belonging to Stemonaceae family was tested for activity against H5N1 neuraminidase. Eight one molecules including stilbenoids, bibenzyls and various others were selected as probable compounds for lead molecules. These lead molecules were tested for toxicity tests and Lipinski rule in Pre ADMET server. Around 33 compounds cleared all these tests. Validated ligand molecules were docked against H5NI Neuraminidase active site residues using AUTODOCK 4 which showed better results in comparison with zanamivir and oseltamivir, anti- influenza drugs.

  20. Kinetics assisted design of catalysts for coal liquefaction. Final report

    Klein, M.T.; Foley, H.C.; Calkins, W.H.; Scouten, C.


    The thermal and catalytic reactions of 4-(1-naphthylmethyl)bibenzyl (NBBM), a resid and coal model compound, were examined. Catalytic reaction of NBBM was carried out at 400 C under hydrogen with a series of transition metal-based catalytic materials including Fe(CO){sub 4}PPh{sub 3}, Fe(CO){sub 3}(PPh{sub 3}){sub 2}, Fe(CO){sub 2}(PPh{sub 3}){sub 2}CS{sub 2}, Fe(CO){sub 5}, Mo(CO){sub 6}, Mn{sub 2}(CO){sub 10}, Fe{sub 2}O{sub 3} and MoS{sub 2}. Experimental findings and derived mechanistic insights were organized into molecular-level reaction models for NBBM pyrolysis and catalysis. Hydropyrolysis and catalysis reaction families occurring during NBBM hydropyrolysis at 420 C were summarized in the form of reaction matrices which, upon exhaustive application to the components of the reacting system, yielded the mechanistic reaction model. Each reaction family also had an associated linear free energy relationship (LFER) which provided an estimate of the rate constant k{sub i} given a structural property of species i or its reaction. Including the catalytic reaction matrices with those for the pyrolysis model provided a comprehensive NBBM catalytic reaction model and allowed regression of fundamental LFER parameters for the catalytic reaction families. The model also allowed specification of the property of an optimal catalyst. Iron, molybdenum and palladium were predicted to be most effective for model compound consumption. Due to the low costs associated with iron and its disposal, it is a good choice for coal liquefaction catalysis and the challenge remains to synthesize small particles able to access the full surface area of the coal macromolecule.

  1. Engineering architecture of the neutron Time-of-Flight (nToF) diagnostic suite at the National Ignition Facility

    Clancy, T. J.; Caggiano, J.; McNaney, J.; Eckart, M.; Moran, M.; Glebov, V. Y.; Knauer, J.; Hatarik, R.; Friedrich, S.; Zacharias, R.; Carpenter, A.; Shoup, M. J.; Buczek, T.; Yeoman, M.; Zeid, Z.; Zaitseva, N.; Talison, B.; Worden, J.; Rice, B.; Duffy, T.; Pruyne, A.; Marshall, K.


    This paper describes the engineering architecture and function of the neutron Time-of-Flight (nToF) diagnostic suite installed on the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL). These instruments provide key measures of neutron yield, ion temperature, drift velocity, neutron bang-time, and neutron downscatter ratio. Currently, there are five nToFs on three collimated lines-of-site (LOS) from 18m to 27m from Target Chamber Center, and three positioned 4.5m from TCC, within the NIF Target Chamber but outside the vacuum and confinement boundary by use of re-entrant wells on three other LOS. NIF nToFs measure the time history and equivalent energy spectrum of reaction generated neutrons from a NIF experiment. Neutrons are transduced to electrical signals, which are then carried either by coaxial or Mach-Zehnder transmission systems that feed divider assemblies and fiducially timed digitizing oscilloscopes outside the NIF Target Bay (TB) radiation shield wall. One method of transduction employs a two-stage process wherein a neutron is converted to scintillation photons in hydrogen doped plastic (20x40mm) or bibenzyl crystals (280x1050mm), which are subsequently converted to an electrical signal via a photomultiplier tube or a photo-diode. An alternative approach uses a single-stage conversion of neutrons-to-electrons by use of a thin (0.25 to 2 mm) Chemical Vapor Deposition Diamond (CVDD) disc (2 to 24mm radius) under high voltage bias. In comparison to the scintillator method, CVDDs have fast rise and decay times (




    Inadequacies of current recovery and disposal methods for mixed plastic wastes drive the exploration of viable strategies for plastics resource recovery. The combination of diminishing landfill space and increasing usage of plastic products poses a significant dilemma, since current recovery methods are costly and ill-suited to handle contaminants. Coprocessing of polymeric waste with other materials may provide potential solutions to the deficiencies of current resource recovery methods, including unfavorable process economics. By incorporating plastic waste as a minor feed into an existing process, variations in supply and composition could be mediated, permitting continuous operation. One attractive option is the coprocessing of polymeric waste with coal under direct liquefaction conditions, allowing for simultaneous conversion of both feedstocks into high-valued products. Catalyst-directed coliquefaction of coal and polymeric materials not only has attractive environmental implications but also has the potential to enhance the economic viability of traditional liquefaction processes. By exploiting the higher H/C ratio of the polymeric material and using it as a hydrogen source, the overall process demand for molecular hydrogen and hydrogen donor solvents may be reduced. A series of model compound experiments has been conducted, providing a starting point for unraveling the complex chemistry underlying coliquefaction of coal and polymeric materials. Tetradecane (C{sub 14} H{sub 30} ) was used as a polyethylene mimic, and 4-(naphthylmethyl)bibenzyl (NBBM) was used as a coal model compound. Neat and binary mixture reactions of tetradecane and NBBM were carried out in an inert atmosphere at both low and high pressures to establish a thermal baseline for subsequent catalytic experiments. Work in the past six months has focused on analysis of light gaseous products for neat reactions of tetradecane, resulting in mass balances greater than 94%. The experimental

  3. Flash vacuum pyrolysis of methoxy-substituted lignin model compounds.

    Britt, P F; Buchanan, A C; Cooney, M J; Martineau, D R


    The flash vacuum pyrolysis (FVP) of methoxy-substituted beta-O-4 lignin model compounds has been studied at 500 degrees C to provide mechanistic insight into the primary reaction pathways that occur under conditions of fast pyrolysis. FVP of PhCH(2)CH(2)OPh (PPE), a model of the dominant beta-O-4 linkage in lignin, proceeds by C-O and C-C cleavage, in a 37:1 ratio, to produce styrene plus phenol as the dominant products and minor amounts of toluene, bibenzyl, and benzaldehyde. From the deuterium isotope effect in the FVP of PhCD(2)CH(2)OPh, it was shown that C-O cleavage occurs by homolysis and by 1,2-elimination in a ratio of 1.4:1, respectively. Methoxy substituents enhance the homolysis of the beta-O-4 linkage, relative to PPE, in o-CH(3)O-C(6)H(4)OCH(2)CH(2)Ph (o-CH(3)O-PPE) and (o-CH(3)O)(2)-C(6)H(3)OCH(2)CH(2)Ph ((o-CH(3)O)(2)-PPE) by a factor of 7.4 and 21, respectively. The methoxy-substituted phenoxy radicals undergo a complex series of reactions, which are dominated by 1,5-, 1,6-, and 1,4-intramolecular hydrogen abstraction, rearrangement, and beta-scission reactions. In the FVP of o-CH(3)O-PPE, the dominant product, salicylaldehyde, forms from the methoxyphenoxy radical by a 1,5-hydrogen shift to form 2-hydroxyphenoxymethyl radical, 1,2-phenyl shift, and beta-scission of a hydrogen atom. The 2-hydroxyphenoxymethyl radical can also cleave to form formaldehyde and phenol in which the ratio of 1, 2-phenyl shift to beta-scission is ca. 4:1. In the FVP of o-CH(3)O-PPE and (o-CH(3)O)(2)-PPE, products (ca. 20 mol %) are also formed by C-O homolysis of the methoxy group. The resulting phenoxy radicals undergo 1,5- and 1,6-hydrogen shifts in a ratio of ca. 2:1 to the aliphatic or benzylic carbon, respectively, of the phenethyl chain. In the FVP of (o-CH(3)O)(2)-PPE, o-cresol was the dominant product. It was formed by decomposition of 2-hydroxy-3-hydroxymethylbenzaldehyde and 2-hydroxybenzyl alcohol, which are formed from a complex series of reactions from the 2

  4. Advances in the of Resources, Constituents and Pharmacological Effects of Dendrobium officinale%铁皮石斛资源、化学成分及药理作用研究进展

    李娟; 李顺祥; 黄丹; 赵兴兵; 蔡光先


    Dendrobium officinale is a valuable medicinal plant, and is widely used in the treatment and daily health care, however, the lack of wild resources and expensive price lead to market disruption of Dendrobium officinale With the maturation of artificial cultivation technology, the problem related to the lack of resources is gradually solved in recent years. Its tissue culture, cultivation, quality control, chemical constituents, pharmacology and clinical applications, etc are studied at home and aboard. Resources of Dendrobium officinal*: in terra of the Latin name, morphological characteristics, commodity, quality evaluation, and genetic diversity are comprehensively summarized, chemical constituents in polysaccharides, ami no acids, trace elements, phenanthrenes, bibenzyls, phenolic acids, and alkaloids are reviewed, and pharmacological effects for improving immune functioning, anti-tumor, anti -aging, lowering blood glucose and blood pressure are integrated. A scientific and theoretical foundation for studying constituents and biological activities of Dendrobium officinale, and for further developing medicinal value of natural products is provided.%铁皮石斛是滋阴补益的名贵药用植物,在治疗和日常保健中应用广泛.由于野生资源的匮乏和价格昂贵等原因,导致市场上的铁皮石斛良莠不齐,掺假严重.随着人工栽培技术的日益成熟,铁皮石斛资源匮乏的问题逐步得到解决.近10年,国内外对其组织培养、种植栽培、鉴别和质量控制、化学成分、药理作用和临床应用等方面进行了大量深入研究.本文主要从铁皮石斛拉丁学名、商品、资源现状、质量评价和遗传多样性等方面综述铁皮石斛的资源情况;对已发现的多糖、氨基酸、微量元素、菲类、联苄类、酚酸类和生物碱等类型的化学成分和提高免疫、抗肿瘤、抗衰老、降血糖和降血压等药理作用进行系统综述,为铁皮石斛化学成分与