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Sample records for active hydroxyl groups

  1. Chemical modification and structure-activity relationships of pyripyropenes. 1. Modification at the four hydroxyl groups.

    PubMed

    Obata, R; Sunazuka, T; Li, Z; Tian, Z; Harigaya, Y; Tabata, N; Tomoda, H; Omura, S

    1996-11-01

    Four hydroxyl groups of pyripyropenes have been modified and evaluated for their ability to inhibit microsomal acyl-CoA:cholesterol acyltransferase (ACAT) activity in vitro and to lower cholesterol absorption in vivo in a cholesterol-fed hamster. 7-O-n-Valeryl derivative (8c) improved the in vitro ACAT inhibitory activity (IC50 = 13 nM) about 7 times better than pyripyropene A. Introduction of methanesulfonyl group at 11-hydroxyl group (17a) increased both in vitro activity (IC50 = 19 nM) and in vivo efficacy (ED50 = 10 mg/kg). PMID:8982343

  2. Organocatalytic chemo- and regioselective oxyarylation of styrenes via a cascade reaction: remote activation of hydroxyl groups.

    PubMed

    Zhang, Yu-Chen; Jiang, Fei; Wang, Shu-Liang; Shi, Feng; Tu, Shu-Jiang

    2014-07-01

    The first organocatalytic oxyarylation of styrenes has been established through a cascade of vinylogous Michael addition/alkoxyl transfer reactions of o- or p-hydroxylstyrenes with quinone imine ketals. The process leads to a highly chemo- and regioselective oxyarylation of styrenes and provides access to m-alkylated anilines in generally high yields and excellent diastereoselectivity (up to 99% yield, >95:5 dr). An investigation of the reaction pathway revealed that the existence and position of the hydroxyl group of styrene played crucial roles in the cascade reaction, suggesting that the two reactants were simultaneously activated by binaphthyl-derived phosphoric acid via hydrogen bonding interactions and long-distance conjugative effects. In addition, the activating group of the hydroxyl functionality in the products can be easily removed or transformed, demonstrating the applicability and utility of this strategy in styrene oxyarylation and in the synthesis of styrene-based compounds.

  3. The 4'-hydroxyl group of resveratrol is functionally important for direct activation of PPARα.

    PubMed

    Takizawa, Yoshie; Nakata, Rieko; Fukuhara, Kiyoshi; Yamashita, Hiroshi; Kubodera, Hideo; Inoue, Hiroyasu

    2015-01-01

    Long-term moderate consumption of red wine is associated with a reduced risk of developing lifestyle-related diseases such as cardiovascular disease and cancer. Therefore, resveratrol, a constituent of grapes and various other plants, has attracted substantial interest. This study focused on one molecular target of resveratrol, the peroxisome proliferator activated receptor α (PPARα). Our previous study in mice showed that resveratrol-mediated protection of the brain against stroke requires activation of PPARα; however, the molecular mechanisms involved in this process remain unknown. Here, we evaluated the chemical basis of the resveratrol-mediated activation of PPARα by performing a docking mode simulation and examining the structure-activity relationships of various polyphenols. The results of experiments using the crystal structure of the PPARα ligand-binding domain and an analysis of the activation of PPARα by a resveratrol analog 4-phenylazophenol (4-PAP) in vivo indicate that the 4'-hydroxyl group of resveratrol is critical for the direct activation of PPARα. Activation of PPARα by 5 μM resveratrol was enhanced by rolipram, an inhibitor of phosphodiesterase (PDE) and forskolin, an activator of adenylate cyclase. We also found that resveratrol has a higher PDE inhibitory activity (IC50 = 19 μM) than resveratrol analogs trans-4-hydroxystilbene and 4-PAP (IC50 = 27-28 μM), both of which has only 4'-hydroxyl group, indicating that this 4'-hydroxyl group of resveratrol is not sufficient for the inhibition of PDE. This result is consistent with that 10 μM resveratrol has a higher agonistic activity of PPARα than these analogs, suggesting that there is a feedforward activation loop of PPARα by resveratrol, which may be involved in the long-term effects of resveratrol in vivo. PMID:25798826

  4. Facile fabrication of novel cyclomatrix-type polyphosphazene nanotubes with active hydroxyl groups via an in situ template approach

    NASA Astrophysics Data System (ADS)

    Fu, Jianwei; Huang, Xiaobin; Zhu, Yan; Huang, Yawen; Tang, Xiaozhen

    2009-02-01

    Novel polyphosphazene nanotubes with active hydroxyl groups were fabricated via an in situ template approach under ultrasonic irradiation. SEM and TEM results indicated that the nanotubes were uniform with length of several micrometers, inner diameter of ca. 20 nm and outer diameter of 60-80 nm. FTIR spectra revealed that the content of the hydroxyl groups on the nanotube surface was dependent on the feed ratio of hexachlorocyclotriphosphazene (HCCP) to 4,4'-sulfonyldiphenol. The successful esterification of polymer nanotubes with benzoxy chloride demonstrated the high reactivity of the hydroxyl groups. The method employed here might provide a simple and effective way to prepare functional nanotubes used for biological applications.

  5. Role of the phenolic hydroxyl group in the biological activities of simplified analogue of aplysiatoxin with antiproliferative activity.

    PubMed

    Yanagita, Ryo C; Kamachi, Hiroaki; Tanaka, Keisuke; Murakami, Akira; Nakagawa, Yu; Tokuda, Harukuni; Nagai, Hiroshi; Irie, Kazuhiro

    2010-10-15

    The 18-deoxy derivative (3) of a simplified analogue (1) of aplysiatoxin with antiproliferative activity was synthesized to examine the role of the phenolic hydroxyl group at position 18 in the biological activities of 1. Compound 3 as well as 1 showed significant affinity for protein kinase Cδ (PKCδ), and the antiproliferative activity of 3 was slightly higher than that of 1. However, the anti-tumor-promoting activity of 3 was less than that of 1 in vitro, suggesting that the phenolic hydroxyl group of 1 is necessary for the anti-tumor-promoting activity but not for the binding of PKCδ and antiproliferative activity. Moreover, PKC isozyme selectivity of 3 was similar to that of 1, suggesting non-PKC receptors for these compounds to play some roles in the anti-tumor-promoting activity of 1.

  6. Role of allyl group in the hydroxyl and peroxyl radical scavenging activity of S-allylcysteine.

    PubMed

    Maldonado, Perla D; Alvarez-Idaboy, J Raúl; Aguilar-González, Adriana; Lira-Rocha, Alfonso; Jung-Cook, Helgi; Medina-Campos, Omar Noel; Pedraza-Chaverrí, José; Galano, Annia

    2011-11-17

    S-Allylcysteine (SAC) is the most abundant compound in aged garlic extracts, and its antioxidant properties have been demonstrated. It is known that SAC is able to scavenge different reactive species including hydroxyl radical (•OH), although its potential ability to scavenge peroxyl radical (ROO•) has not been explored. In this work the ability of SAC to scavenge ROO• was evaluated, as well as the role of the allyl group (-S-CH(2)-CH═CH(2)) in its free radical scavenging activity. Two derived compounds of SAC were prepared: S-benzylcysteine (SBC) and S-propylcysteine (SPC). Their abilities to scavenge •OH and ROO• were measured. A computational analysis was performed to elucidate the mechanism by which these compounds scavenge •OH and ROO•. SAC was able to scavenge •OH and ROO•, in a concentration-dependent way. Such activity was significantly ameliorated when the allyl group was replaced by benzyl or propyl groups. It was shown for the first time that SAC is able to scavenge ROO•.

  7. Role of hydroxyl groups on the stability and catalytic activity of Au clusters on rutile surface

    SciTech Connect

    Kent, Paul R

    2011-01-01

    Hydroxyls are present as surface terminations of transition metal oxides under ambient conditions and may modify the properties of supported catalysts. We perform first-principles density functional theory calculations to investigate the role of hydroxyls on the catalytic activity of supported gold clusters on TiO{sub 2} (rutile). We find that they have a long-range effect increasing the adhesion of gold clusters on rutile. While hydroxyls make one gold atom more electronegative, a more complex charge-transfer scenario is observed on larger clusters which are important for catalytic applications. This enhances the molecular adsorption and coadsorption energies of CO and O{sub 2}, thereby increasing the catalytic activity of gold clusters for CO oxidation, consistent with reported experiments. Hydroxyls at the interface between gold and rutile surface are most important to this process, even when not directly bound to gold. As such, accurate models of catalytic processes on gold and other catalysts should include the effect of surface hydroxyls.

  8. Anaerobic Activation of p-Cymene in Denitrifying Betaproteobacteria: Methyl Group Hydroxylation versus Addition to Fumarate

    PubMed Central

    Strijkstra, Annemieke; Trautwein, Kathleen; Jarling, René; Wöhlbrand, Lars; Dörries, Marvin; Reinhardt, Richard; Drozdowska, Marta; Golding, Bernard T.; Wilkes, Heinz

    2014-01-01

    The betaproteobacteria “Aromatoleum aromaticum” pCyN1 and “Thauera” sp. strain pCyN2 anaerobically degrade the plant-derived aromatic hydrocarbon p-cymene (4-isopropyltoluene) under nitrate-reducing conditions. Metabolite analysis of p-cymene-adapted “A. aromaticum” pCyN1 cells demonstrated the specific formation of 4-isopropylbenzyl alcohol and 4-isopropylbenzaldehyde, whereas with “Thauera” sp. pCyN2, exclusively 4-isopropylbenzylsuccinate and tentatively identified (4-isopropylphenyl)itaconate were observed. 4-Isopropylbenzoate in contrast was detected with both strains. Proteogenomic investigation of p-cymene- versus succinate-adapted cells of the two strains revealed distinct protein profiles agreeing with the different metabolites formed from p-cymene. “A. aromaticum” pCyN1 specifically produced (i) a putative p-cymene dehydrogenase (CmdABC) expected to hydroxylate the benzylic methyl group of p-cymene, (ii) two dehydrogenases putatively oxidizing 4-isopropylbenzyl alcohol (Iod) and 4-isopropylbenzaldehyde (Iad), and (iii) the putative 4-isopropylbenzoate-coenzyme A (CoA) ligase (Ibl). The p-cymene-specific protein profile of “Thauera” sp. pCyN2, on the other hand, encompassed proteins homologous to subunits of toluene-activating benzylsuccinate synthase (termed [4-isopropylbenzyl]succinate synthase IbsABCDEF; identified subunits, IbsAE) and protein homologs of the benzylsuccinate β-oxidation (Bbs) pathway (termed BisABCDEFGH; all identified except for BisEF). This study reveals that two related denitrifying bacteria employ fundamentally different peripheral degradation routes for one and the same substrate, p-cymene, with the two pathways apparently converging at the level of 4-isopropylbenzoyl-CoA. PMID:25261521

  9. Boron-doped bismuth oxybromide microspheres with enhanced surface hydroxyl groups: Synthesis, characterization and dramatic photocatalytic activity.

    PubMed

    Liu, ZhangSheng; Liu, JinLong; Wang, HaiYang; Cao, Gang; Niu, JiNan

    2016-02-01

    B-doped BiOBr photocatalysts were successfully synthesized via a facile solvothermal method with boric acid used as boron source. As-obtained products consist of novel hierarchical microspheres, whose nanosheet building units were formed by nanoparticles splicing. They showed dramatic photocatalytic efficiency toward the degradation of Rhodamine B (RhB) and phenol under the visible-light irradiation and the highest activity was achieved by 0.075B-BiOBr. The enhanced photocatalytic activity could be attributed to the enriched surface hydroxyl groups on B-doped BiOBr samples, which not only improved the adsorption of pollutant on the photocatalyst but also promoted the separation of photogenerated electron-hole pairs. In addition, it was found that the main reactive species responsible for the degradation of organic pollutant were h(+) and O2(-) radicals, instead of OH radicals. PMID:26590875

  10. Boron-doped bismuth oxybromide microspheres with enhanced surface hydroxyl groups: Synthesis, characterization and dramatic photocatalytic activity.

    PubMed

    Liu, ZhangSheng; Liu, JinLong; Wang, HaiYang; Cao, Gang; Niu, JiNan

    2016-02-01

    B-doped BiOBr photocatalysts were successfully synthesized via a facile solvothermal method with boric acid used as boron source. As-obtained products consist of novel hierarchical microspheres, whose nanosheet building units were formed by nanoparticles splicing. They showed dramatic photocatalytic efficiency toward the degradation of Rhodamine B (RhB) and phenol under the visible-light irradiation and the highest activity was achieved by 0.075B-BiOBr. The enhanced photocatalytic activity could be attributed to the enriched surface hydroxyl groups on B-doped BiOBr samples, which not only improved the adsorption of pollutant on the photocatalyst but also promoted the separation of photogenerated electron-hole pairs. In addition, it was found that the main reactive species responsible for the degradation of organic pollutant were h(+) and O2(-) radicals, instead of OH radicals.

  11. Rapeseed lecithin hydroxylation by chlorine replacing with hydroxyl groups in chlorinated phospholipids.

    PubMed

    Górecki, Michał; Sosada, Marian; Boryczka, Monika; Fraś, Pawel; Pasker, Beata

    2012-01-01

    Rapeseed lecithin ethanol soluble fraction (LESF) was hydroxylated with 30% hydrogen peroxide in the presence of acetic acid. The product was compared to the one obtained by method based on nucleophilic substitution reaction of phospholipids chlorine derivatives. In this approach, hydrogen chloride was added to double bonds in unsaturated acyl groups of phospholipids. Next, chlorine was replaced with hydroxyl groups via the alkaline hydrolysis of chlorine derivatives. The surface active properties of the products obtained with the usage of two methods of rapeseed LESF hydroxylation were determined. The minimal surface tension (eta(min), mN/m) and the critical micelle concentration (CMC, g/L) of LESF hydroxylated with hydrogen peroxide (20.2 mN/m, 6.0 g/L) and obtained by chlorine replacing with hydroxyl groups in chlorinated phospholipids (25.0 mN/m, 9.8 g/L) were compared to LESF (31.8 mN/m, 17.8 g/L). Hydroxylated LESF obtained by lecithin chlorination and chlorine replacing with hydroxyl groups in the chlorine derivatives has no peroxides and the good surface active properties. The product as an effective emulsifier can be used in pharmacy and cosmetics.

  12. Hashish. Importance of the phenolic hydroxyl group in tetrahydrocannabinols.

    PubMed

    Uliss, D B; Dalzell, H C; Handrick, G R; Howes, J F; Razdan, R K

    1975-02-01

    Optically active delta-3- and delta-8-tetrahydrocannabinols (THC's), cannabidiol and racemic delta-9-cis-THC, and their corresponding analogs (1b yields 4b) in which the positions of the phenolic hydroxyl group and the n-C5 side chain have been interchanged are compared in selected pharmacological tests in mice. the results indicate that the phenolic hydroxyl group in the 1 position in THC's is very important for eliciting activity and that cannabidiol and delta-9-cis-THC possess weak CNS depressant properties.

  13. Structure-Activity Relationship of Synthetic 2-Phenylnaphthalenes with Hydroxyl Groups that Inhibit Proliferation and Induce Apoptosis of MCF-7 Cancer Cells

    PubMed Central

    Chang, Chi-Fen; Ke, Ci-Yi; Wu, Yang-Chang; Chuang, Ta-Hsien

    2015-01-01

    In this study, six 2-phenylnaphthalenes with hydroxyl groups were synthesized in high yields by the demethylation of the corresponding methoxy-2-phenylnaphthalenes, and one 2-phenylnaphthalene with an amino group was obtained by hydrogenation. All of the 2-phenylnaphthalene derivatives were evaluated for cytotoxicity, and the structure-activity relationship (SAR) against human breast cancer (MCF-7) cells was also determined. The SAR results revealed that cytotoxicity was markedly promoted by the hydroxyl group at the C-7 position of the naphthalene ring. The introduction of hydroxyl groups at the C-6 position of the naphthalene ring and the C-4' position of the phenyl ring fairly enhanced cytotoxicity, but the introduction of a hydroxyl group at the C-3' position of the phenyl ring slightly decreased cytotoxicity. Overall, 6,7-dihydroxy-2-(4'-hydroxyphenyl)naphthalene (PNAP-6h) exhibited the best cytotoxicity, with an IC50 value of 4.8 μM against the MCF-7 cell line, and showed low toxicity toward normal human mammary epithelial cells (MCF-10A). PNAP-6h led to cell arrest at the S phase, most likely due to increasing levels of p21 and p27 and decreasing levels of cyclin D1, CDK4, cyclin E, and CDK2. In addition, PNAP-6h decreased CDK1 and cyclin B1 expression, most likely leading to G2/M arrest, and induced morphological changes, such as nuclear shrinkage, nuclear fragmentation, and nuclear hypercondensation, as observed by Hoechst 33342 staining. PNAP-6h induced apoptosis, most likely by the promotion of Fas expression, increased PARP activity, caspase-7, caspase-8, and caspase-9 expression, the Bax/Bcl-2 ratio, and the phosphorylation of p38, and decreased the phosphorylation of ERK. This study provides the first demonstration of the cytotoxicity of PNAPs against MCF-7 cells and elucidates the mechanism underlying PNAP-induced cytotoxicity. PMID:26492346

  14. The Hydroxyl at Position C1 of Genipin Is the Active Inhibitory Group that Affects Mitochondrial Uncoupling Protein 2 in Panc-1 Cells

    PubMed Central

    Hou, Jianwei; Ding, Yue; Zhang, Tong; Zhang, Yong; Wang, Jianying; Shi, Chenchen; Fu, Wenwei; Cai, Zhenzhen

    2016-01-01

    Genipin (GNP) effectively inhibits uncoupling protein 2 (UCP2), which regulates the leakage of protons across the inner mitochondrial membrane. UCP2 inhibition may induce pancreatic adenocarcinoma cell death by increasing reactive oxygen species (ROS) levels. In this study, the hydroxyls at positions C10 (10-OH) and C1 (1-OH) of GNP were hypothesized to be the active groups that cause these inhibitory effects. Four GNP derivatives in which the hydroxyl at position C10 or C1 was replaced with other chemical groups were synthesized and isolated. Differences in the inhibitory effects of GNP and its four derivatives on pancreatic carcinoma cell (Panc-1) proliferation were assessed. The effects of GNP and its derivatives on apoptosis, UCP2 inhibition and ROS production were also studied to explore the relationship between GNP’s activity and its structure. The derivatives with 1-OH substitutions, geniposide (1-GNP1) and 1-ethyl-genipin (1-GNP2) lacked cytotoxic effects, while the other derivatives that retained 1-OH, 10-piv-genipin (10-GNP1) and 10-acetic acid-genipin (10-GNP2) exerted biological effects similar to those of GNP, even in the absence of 10-OH. Thus, 1-OH is the key functional group in the structure of GNP that is responsible for GNP’s apoptotic effects. These cytotoxic effects involve the induction of Panc-1 cell apoptosis through UCP2 inhibition and subsequent ROS production. PMID:26771380

  15. The Hydroxyl at Position C1 of Genipin Is the Active Inhibitory Group that Affects Mitochondrial Uncoupling Protein 2 in Panc-1 Cells.

    PubMed

    Yang, Yang; Yang, Yifu; Hou, Jianwei; Ding, Yue; Zhang, Tong; Zhang, Yong; Wang, Jianying; Shi, Chenchen; Fu, Wenwei; Cai, Zhenzhen

    2016-01-01

    Genipin (GNP) effectively inhibits uncoupling protein 2 (UCP2), which regulates the leakage of protons across the inner mitochondrial membrane. UCP2 inhibition may induce pancreatic adenocarcinoma cell death by increasing reactive oxygen species (ROS) levels. In this study, the hydroxyls at positions C10 (10-OH) and C1 (1-OH) of GNP were hypothesized to be the active groups that cause these inhibitory effects. Four GNP derivatives in which the hydroxyl at position C10 or C1 was replaced with other chemical groups were synthesized and isolated. Differences in the inhibitory effects of GNP and its four derivatives on pancreatic carcinoma cell (Panc-1) proliferation were assessed. The effects of GNP and its derivatives on apoptosis, UCP2 inhibition and ROS production were also studied to explore the relationship between GNP's activity and its structure. The derivatives with 1-OH substitutions, geniposide (1-GNP1) and 1-ethyl-genipin (1-GNP2) lacked cytotoxic effects, while the other derivatives that retained 1-OH, 10-piv-genipin (10-GNP1) and 10-acetic acid-genipin (10-GNP2) exerted biological effects similar to those of GNP, even in the absence of 10-OH. Thus, 1-OH is the key functional group in the structure of GNP that is responsible for GNP's apoptotic effects. These cytotoxic effects involve the induction of Panc-1 cell apoptosis through UCP2 inhibition and subsequent ROS production.

  16. A ribozyme that triphosphorylates RNA 5′-hydroxyl groups

    PubMed Central

    Moretti, Janina E.; Müller, Ulrich F.

    2014-01-01

    The RNA world hypothesis describes a stage in the early evolution of life in which RNA served as genome and as the only genome-encoded catalyst. To test whether RNA world organisms could have used cyclic trimetaphosphate as an energy source, we developed an in vitro selection strategy for isolating ribozymes that catalyze the triphosphorylation of RNA 5′-hydroxyl groups with trimetaphosphate. Several active sequences were isolated, and one ribozyme was analyzed in more detail. The ribozyme was truncated to 96 nt, while retaining full activity. It was converted to a trans-format and reacted with rates of 0.16 min−1 under optimal conditions. The secondary structure appears to contain a four-helical junction motif. This study showed that ribozymes can use trimetaphosphate to triphosphorylate RNA 5′-hydroxyl groups and suggested that RNA world organisms could have used trimetaphosphate as their energy source. PMID:24452796

  17. Structure–activity relationship of Au/ZrO2 catalyst on formation of hydroxyl groups and its influence on CO oxidation

    SciTech Connect

    Karwacki, Christopher J.; Ganesh, P.; Kent, Paul R. C.; Gordon, Wesley O.; Peterson, Gregory W.; Niu, Jun Jie; Gogotsi, Yury

    2013-01-01

    The effect of changes in morphology and surface hydroxyl species upon thermal treatment of zirconia on the oxidation activity of Au/ZrO2 catalyst was studied. We observed using transmission fourier transform infrared (FTIR) spectroscopy progressive changes in the presence of monodentate (type I), bidentate (type II) and hydrogen bridged species (type III) for each of the thermally treated (85 to 500 C) supports consisting of bare zirconia and Au/ZrO2 catalysts. Furthermore, structural changes in zirconia were accompanied by an increase in crystal size (7 to 58 nm) and contraction of the supports porosity (SSA 532 to 7 m2/g) with increasing thermal treatment. Deposition of gold nanoparticles under similar preparation conditions on different thermally treated zirconia resulted in changes in the mean gold cluster size, ranging from 3.7 to 5.6 nm. Changes in the surface hydroxyl species, support structure and size of the gold centers are important parameters responsible for the observed decrease (> 90 %) in CO conversion activity for the Au/ZrO2 catalysts. Density functional theory calculations provide evidence of increased CO binding to Au nanoclusters in the presence of surface hydroxyls on zirconia, which increases charge transfer at the perimeter of the gold nanocluster on zirconia support. This further helps in reducing a model CO-oxidation reaction barrier in the presence of surface hydroxyls. This work demonstrates the need to understand the structure-activity relationship of both the support and active particles for the design of catalytic materials.

  18. Coumarin-fused coumarin: antioxidant story from N,N-dimethylamino and hydroxyl groups.

    PubMed

    Xi, Gao-Lei; Liu, Zai-Qun

    2015-04-01

    Two coumarin skeletons can form chromeno[3,4-c]chromene-6,7-dione by sharing with the C ═ C in lactone. The aim of the present work was to explore the antioxidant effectiveness of the coumarin-fused coumarin via six synthetic compounds containing hydroxyl and N,N-dimethylamino as the functional groups. The abilities to quench 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate) cationic radical (ABTS(+•)), 2,2'-diphenyl-1-picrylhydrazyl radical (DPPH), and galvinoxyl radical revealed that the rate constant for scavenging radicals was related to the amount of hydroxyl group in the scaffold of coumarin-fused coumarin. But coumarin-fused coumarin was able to inhibit DNA oxidations caused by (•)OH, Cu(2+)/glutathione (GSH), and 2,2'-azobis(2-amidinopropane hydrochloride) (AAPH) even in the absence of hydroxyl group. In particular, a hydroxyl and an N,N-dimethylamino group locating at different benzene rings increased the inhibitory effect of coumarin-fused coumarin on AAPH-induced oxidation of DNA about 3 times higher than a single hydroxyl group, whereas N,N-dimethylamino-substituted coumarin-fused coumarin possessed high activity toward (•)OH-induced oxidation of DNA without the hydroxyl group contained. Therefore, the hydroxyl group together with N,N-dimethylamino group may be a novel combination for the design of coumarin-fused heterocyclic antioxidants.

  19. New and extended parameterization of the thermodynamic model AIOMFAC: calculation of activity coefficients for organic-inorganic mixtures containing carboxyl, hydroxyl, carbonyl, ether, ester, alkenyl, alkyl, and aromatic functional groups

    NASA Astrophysics Data System (ADS)

    Zuend, A.; Marcolli, C.; Booth, A. M.; Lienhard, D. M.; Soonsin, V.; Krieger, U. K.; Topping, D. O.; McFiggans, G.; Peter, T.; Seinfeld, J. H.

    2011-05-01

    We present a new and considerably extended parameterization of the thermodynamic activity coefficient model AIOMFAC (Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients) at room temperature. AIOMFAC combines a Pitzer-like electrolyte solution model with a UNIFAC-based group-contribution approach and explicitly accounts for interactions between organic functional groups and inorganic ions. Such interactions constitute the salt-effect, may cause liquid-liquid phase separation, and affect the gas-particle partitioning of aerosols. The previous AIOMFAC version was parameterized for alkyl and hydroxyl functional groups of alcohols and polyols. With the goal to describe a wide variety of organic compounds found in atmospheric aerosols, we extend here the parameterization of AIOMFAC to include the functional groups carboxyl, hydroxyl, ketone, aldehyde, ether, ester, alkenyl, alkyl, aromatic carbon-alcohol, and aromatic hydrocarbon. Thermodynamic equilibrium data of organic-inorganic systems from the literature are critically assessed and complemented with new measurements to establish a comprehensive database. The database is used to determine simultaneously the AIOMFAC parameters describing interactions of organic functional groups with the ions H+, Li+, Na+, K+, NH4+, Mg2+, Ca2+, Cl-, Br-, NO3-, HSO4-, and SO42-. Detailed descriptions of different types of thermodynamic data, such as vapor-liquid, solid-liquid, and liquid-liquid equilibria, and their use for the model parameterization are provided. Issues regarding deficiencies of the database, types and uncertainties of experimental data, and limitations of the model, are discussed. The challenging parameter optimization problem is solved with a novel combination of powerful global minimization algorithms. A number of exemplary calculations for systems containing atmospherically relevant aerosol components are shown. Amongst others, we discuss aqueous mixtures of ammonium sulfate with

  20. New and extended parameterization of the thermodynamic model AIOMFAC: calculation of activity coefficients for organic-inorganic mixtures containing carboxyl, hydroxyl, carbonyl, ether, ester, alkenyl, alkyl, and aromatic functional groups

    NASA Astrophysics Data System (ADS)

    Zuend, A.; Marcolli, C.; Booth, A. M.; Lienhard, D. M.; Soonsin, V.; Krieger, U. K.; Topping, D. O.; McFiggans, G.; Peter, T.; Seinfeld, J. H.

    2011-09-01

    We present a new and considerably extended parameterization of the thermodynamic activity coefficient model AIOMFAC (Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients) at room temperature. AIOMFAC combines a Pitzer-like electrolyte solution model with a UNIFAC-based group-contribution approach and explicitly accounts for interactions between organic functional groups and inorganic ions. Such interactions constitute the salt-effect, may cause liquid-liquid phase separation, and affect the gas-particle partitioning of aerosols. The previous AIOMFAC version was parameterized for alkyl and hydroxyl functional groups of alcohols and polyols. With the goal to describe a wide variety of organic compounds found in atmospheric aerosols, we extend here the parameterization of AIOMFAC to include the functional groups carboxyl, hydroxyl, ketone, aldehyde, ether, ester, alkenyl, alkyl, aromatic carbon-alcohol, and aromatic hydrocarbon. Thermodynamic equilibrium data of organic-inorganic systems from the literature are critically assessed and complemented with new measurements to establish a comprehensive database. The database is used to determine simultaneously the AIOMFAC parameters describing interactions of organic functional groups with the ions H+, Li+, Na+, K+, NH4+, Mg2+, Ca2+, Cl-, Br-, NO3-, HSO4-, and SO42-. Detailed descriptions of different types of thermodynamic data, such as vapor-liquid, solid-liquid, and liquid-liquid equilibria, and their use for the model parameterization are provided. Issues regarding deficiencies of the database, types and uncertainties of experimental data, and limitations of the model, are discussed. The challenging parameter optimization problem is solved with a novel combination of powerful global minimization algorithms. A number of exemplary calculations for systems containing atmospherically relevant aerosol components are shown. Amongst others, we discuss aqueous mixtures of ammonium sulfate with

  1. Reduced serum hydroxyl radical scavenging activity in erythropoietin therapy resistant renal anemia.

    PubMed

    Hirayama, Aki; Nagase, Sohji; Gotoh, Michihiro; Ueda, Atsushi; Ishizu, Takashi; Yoh, Keigyou; Aoyagi, Kazumasa; Terao, Junji; Koyama, Akio

    2002-11-01

    Relation between anemia resistant to recombinant human erythropoietin (rHuEPO) therapy and the oxidative stress in hemodialysis (HD) patients was investigated. Stable HD patients who had consistent hemoglobin concentrations on a constant dose of rHuEPO were studied. Patients were excluded if there were factors that might affect hemopoiesis or administration of antioxidant supplements. Patients were classified into three groups: High (9000 U/week), Low (1500-4500 U/week) and No rHuEPO group. Thiobarbituric acid reactive substances (TBARS) of sera and erythrocyte were examined. Serum superoxide and hydroxyl radical scavenging activities were measured using electron spin resonance. TBARS in the erythrocyte was higher in High rHuEPO group compared with No rHuEPO group, though the serum TBARS were similar. A diminution of serum hydroxyl radical scavenging activity was observed in High rHuEPO group. Hydroxyl radical signal intensity showed a strong correlation with the serum ferritin in High rHuEPO group, although ferritin concentrations were not different among the 3 groups. Superoxide scavenging activity showed no differences. These results indicate that increased lipid peroxidation in erythrocyte, raised by decreased serum hydroxyl radical scavenging activity, is one cause of rHuEPO resistant anemia. Serum ferritin may be involved in this hydroxyl radical production.

  2. The Juxtaposition of Ribose Hydroxyl Groups: The Root of Biological Catalysis and the RNA World?

    NASA Astrophysics Data System (ADS)

    Bernhardt, Harold S.

    2015-06-01

    We normally think of enzymes as being proteins; however, the RNA world hypothesis suggests that the earliest biological catalysts may have been composed of RNA. One of the oldest surviving RNA enzymes we are aware of is the peptidyl transferase centre (PTC) of the large ribosomal RNA, which joins amino acids together to form proteins. Recent evidence indicates that the enzymatic activity of the PTC is principally due to ribose 2 '-OHs. Many other reactions catalyzed by RNA and/or in which RNA is a substrate similarly utilize ribose 2 '-OHs, including phosphoryl transfer reactions that involve the cleavage and/or ligation of the ribose-phosphate backbone. It has recently been proposed by Yakhnin (2013) that phosphoryl transfer reactions were important in the prebiotic chemical evolution of RNA, by enabling macromolecules composed of polyols joined by phosphodiester linkages to undergo recombination reactions, with the reaction energy supplied by the phosphodiester bond itself. The almost unique juxtaposition of the ribose 2'-hydroxyl and 3'-oxygen in ribose-containing polymers such as RNA, which gives ribose the ability to catalyze such reactions, may have been an important factor in the selection of ribose as a component of the first biopolymer. In addition, the juxtaposition of hydroxyl groups in free ribose: (i) allows coordination of borate ions, which could have provided significant and preferential stabilization of ribose in a prebiotic environment; and (ii) enhances the rate of permeation by ribose into a variety of lipid membrane systems, possibly favouring its incorporation into early metabolic pathways and an ancestral ribose-phosphate polymer. Somewhat more speculatively, hydrogen bonds formed by juxtaposed ribose hydroxyl groups may have stabilized an ancestral ribose-phosphate polymer against degradation (Bernhardt and Sandwick 2014). I propose that the almost unique juxtaposition of ribose hydroxyl groups constitutes the root of both biological

  3. Zn(OTf)2-promoted chemoselective esterification of hydroxyl group bearing carboxylic acids.

    PubMed

    Mamidi, Narsimha; Manna, Debasis

    2013-03-15

    Selective esterification of aliphatic and aromatic carboxylic acids with various alcohols is studied using triphenylphosphine, I2, and a catalytic amount of Zn(OTf)2. Use of this catalyst allows the formation of esters at a faster rate with good to excellent yield by activating the in situ generated acyloxyphosphonium ion intermediate. During the esterification process, both their aromatic and aliphatic hydroxyl groups are fully preserved from transesterification. The results show that the bulkiness and the reactivity of this doubly activated intermediate III control the selectivity and the rate of the reaction, respectively. The method is also useful for direct amidation reactions.

  4. Regioselective and stereospecific hydroxylation of GR24 by Sorghum bicolor and evaluation of germination inducing activities of hydroxylated GR24 stereoisomers toward seeds of Striga species.

    PubMed

    Ueno, Kotomi; Ishiwa, Shunsuke; Nakashima, Hitomi; Mizutani, Masaharu; Takikawa, Hirosato; Sugimoto, Yukihiro

    2015-09-15

    Bioconversion of GR24, the most widely used synthetic strigolactone (SL), by hydroponically grown sorghum (Sorghum bicolor) and biological activities of hydroxylated GR24 stereoisomers were studied. Analysis of extracts and exudates of sorghum roots previously fed with a racemic and diastereomeric mixture of GR24, using liquid chromatography-tandem mass spectrometry with multiple reaction monitoring (MRM), confirmed uptake of GR24 and suggested its conversion to mono-hydroxylated products. Two major GR24 metabolites, 7-hydroxy-GR24 and 8-hydroxy-GR24, were identified in the root extracts and exudates by direct comparison of chromatographic behavior with a series of synthetic mono-hydroxylated GR24 analogues. Separate feeding experiments with each of the GR24 stereoisomers revealed that the hydroxylated products were derived from 2'-epi-GR24, an evidence of sterical recognition of the GR24 molecule by sorghum. Trans-4-hydroxy-GR24 isomers derived from all GR24 stereoisomers were detected in the exudates as minor metabolites. The synthetic hydroxy-GR24 isomers induced germination of Striga hermonthica in decreasing order of C-8>C-7>C-6>C-5>C-4. In contrast the stereoisomers having the same configuration of orobanchol, irrespective of position of hydroxylation, induced germination of Striga gesnerioides. The results confirm previous reports on structural requirements of SLs and ascribe a critical role to hydroxylation, but not to the position of the hydroxyl group in the AB part of the molecule, in induction of S. gesnerioides seed germination.

  5. Vanadium promotes hydroxyl radical formation by activated human neutrophils.

    PubMed

    Fickl, Heidi; Theron, Annette J; Grimmer, Heidi; Oommen, Joyce; Ramafi, Grace J; Steel, Helen C; Visser, Susanna S; Anderson, Ronald

    2006-01-01

    This study was undertaken to investigate the effects of vanadium in the +2, +3, +4, and +5 valence states on superoxide generation, myeloperoxidase (MPO) activity, and hydroxyl radical formation by activated human neutrophils in vitro, using lucigenin-enhanced chemiluminescence (LECL), autoiodination, and electron spin resonance with 5,5-dimethyl-l-pyrroline N-oxide as the spin trap, respectively. At concentrations of up to 25 microM, vanadium, in the four different valence states used, did not affect the LECL responses of neutrophils activated with either the chemoattractant, N-formyl-l-methionyl-l-leucyl-l-phenylalanine (1 microM), or the phorbol ester, phorbol 12-myristate 12-acetate (25 ng/ml). However, exposure to vanadium in the +2, +3, and +4, but not the +5, valence states was accompanied by significant augmentation of hydroxyl radical formation by activated neutrophils and attenuation of MPO-mediated iodination. With respect to hydroxyl radical formation, similar effects were observed using cell-free systems containing either hydrogen peroxide (100 microM) or xanthine/xanthine oxidase together with vanadium (+2, +3, +4), while the activity of purified MPO was inhibited by the metal in these valence states. These results demonstrate that vanadium in the +2, +3, and +4 valence states interacts prooxidatively with human neutrophils, competing effectively with MPO for hydrogen peroxide to promote formation of the highly toxic hydroxyl radical.

  6. Substrate specificity of small-intestinal lactase. Assessment of the role of the substrate hydroxyl groups.

    PubMed

    Rivera-Sagredo, A; Cañada, F J; Nieto, O; Jimenez-Barbero, J; Martín-Lomas, M

    1992-10-01

    Lactase-phlorizin hydrolase is a disaccharidase present in the small intestine of mammals. This enzyme has two active sites, one being responsible for the hydrolysis of lactose. Lactase activity is thought to be selective towards glycosides with a hydrophilic aglycon. In this work, we report a systematic study on the importance of each hydroxyl group in the substrate molecule for lactase activity. For this purpose, all of the monodeoxy derivatives of methyl beta-lactoside and other lactose analogues are studied as lactase substrates. With respect to the galactose moiety, it is shown here that HO-3' and HO-2' are necessary for hydrolysis of the substrates by lactase. Using these chemically modified substrates, it has been confirmed that lactase does not behave as a typical beta-galactosidase, since it does not show an absolute selectivity with respect to substitution and stereochemistry at C4' in the galactose moiety of the substrate. However, the glucose moiety, in particular the HO-6, appears to be important for substrate hydrolysis, although none of the hydroxyl groups seemed to be essential. In order to differentiate both activities of the enzyme, a new assay for the phlorizin-hydrolase activity has also been developed.

  7. Coumestan inhibits radical-induced oxidation of DNA: is hydroxyl a necessary functional group?

    PubMed

    Xi, Gao-Lei; Liu, Zai-Qun

    2014-06-18

    Coumestan is a natural tetracycle with a C═C bond shared by a coumarin moiety and a benzofuran moiety. In addition to the function of the hydroxyl group on the antioxidant activity of coumestan, it is worth exploring the influence of the oxygen-abundant scaffold on the antioxidant activity as well. In this work, seven coumestans containing electron-withdrawing and electron-donating groups were synthesized to evaluate the abilities to trap 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate) cationic radical (ABTS(•+)), 2,2'-diphenyl-1-picrylhydrazyl radical (DPPH), and galvinoxyl radical, respectively, and to inhibit the oxidations of DNA mediated by (•)OH, Cu(2+)/glutathione (GSH), and 2,2'-azobis(2-amidinopropane hydrochloride) (AAPH), respectively. It was found that all of the coumestans used herein can quench the aforementioned radicals and can inhibit (•)OH-, Cu(2+)/GSH-, and AAPH-induced oxidations of DNA. In particular, substituent-free coumestan exhibits higher ability to quench DPPH and to inhibit AAPH-induced oxidation of DNA than Trolox. In addition, nonsubstituted coumestan shows a similar ability to inhibit (•)OH- and Cu(2+)/GSH-induced oxidations of DNA relative to that of Trolox. The antioxidant effectiveness of the coumestan can be attributed to the lactone in the coumarin moiety and, therefore, a hydroxyl group may not be a necessary functional group for coumestan to be an antioxidant.

  8. Synthesis and antioxidant activity of hydroxylated phenanthrenes as cis-restricted resveratrol analogues.

    PubMed

    Ding, De-Jun; Cao, Xiao-Yan; Dai, Fang; Li, Xiu-Zhuang; Liu, Guo-Yun; Lin, Dong; Fu, Xing; Jin, Xiao-Ling; Zhou, Bo

    2012-12-01

    Five hydroxylated phenanthrenes as "cis-configuration-fixed" resveratrol analogues differing in the number and position of the hydroxyl groups were designed and synthesized. Their antioxidant activity was studied by ferric reducing antioxidant power, 2,2-diphenyl-1-picrylhydrazyl free radical-scavenging, and DNA strand breakage-inhibiting assays, corresponding to their electron-donating, hydrogen-transfer and DNA-protecting abilities, respectively. In the above assays, their activity depends significantly on the number and position of the hydroxyl groups, and most of them are more effective than resveratrol. Noticeably, compound 9b (2,4,6-trihydroxyl phenanthrene) with the same hydroxyl group substitutions as resveratrol, is superior to the reference compound, highlighting the importance of extension of the conjugation over multiple aromatic-rings. Similar activity sequences were obtained in different experimental models, but the appreciable differences could contribute detailed insights into antioxidant mechanisms. Based on these results, the hydroxylated phenanthrenes may be considered as a novel type of resveratrol-directed antioxidants.

  9. Monitoring of hydroxyl groups in wood during heat treatment using NIR spectroscopy.

    PubMed

    Mitsui, Katsuya; Inagaki, Tetsuya; Tsuchikawa, Satoru

    2008-01-01

    This paper deals with the evaluation of thermally treated wood by near-infrared (NIR) spectroscopy. In the NIR second derivative spectrum, the absorption band at 6913 cm(-1) appeared with the procession of heat treatment, which conclusively assigned to the phenolic hydroxyl groups due to the lignin in comparison with the spectrum of acetylated spruce wood. As a result of the changes in the ratio of the areal integral calculated from spectral separation in the region of hydroxyl groups (7200-6100 cm(-1)) by the Gauss-Newton method, it was clear that the degradation of hydroxyl group in the cellulose started predominantly from the amorphous region and followed to semicrystalline and crystalline region. There was an obvious correlation between the weight decrement of wood and the decrement of hydroxyl groups in the cellulose by heat treatment.

  10. Reducing the conformational flexibility of carbohydrates: locking the 6-hydroxyl group by cyclopropanes.

    PubMed

    Brand, Christian; Granitzka, Markus; Stalke, Dietmar; Werz, Daniel B

    2011-10-14

    The 6-hydroxyl group of hexopyranosides was stereochemically locked by the spiroannelation of a cyclopropane unit at C-5. The corresponding glucose and mannose derivatives were prepared and their behaviour in glycosidation reactions was studied.

  11. The effect of hydroxyl group on the electronic structure of carbon nanotubes with different diameters

    NASA Astrophysics Data System (ADS)

    Kheirmand, M.

    2016-09-01

    A single hydroxyl group is functionalized on both sides of one ring of several carbon nanotubes (CNT) as CNT-OH. The electronic structure and chemical bonding parameters are studied with the help of quantum theory of atoms in molecules (QTAIM). Anionic states of the CNT-O as deprotonated hydroxyl are studied in order to get insight into the nature of CNT-OH species, considering frozen and relaxed geometries of CNT-O compounds. The results show a significant difference between inside or outside substituted hydroxyl groups; and also complicated behavior of the CNT's diameter, and it can be concluded that hydroxyl group can be used to tune the CNT's properties, effectively, in interesting application of these nanostructures.

  12. Diffusion of hydroxyl groups in silica glass through the binding interface

    NASA Astrophysics Data System (ADS)

    Sato, Naoya; Yamamoto, Takaki; Kuzuu, Nobu; Horikoshi, Hideharu; Niwa, Shohei

    2016-02-01

    Diffusion of hydroxyl groups in silica glass through an interface formed by binding between high-hydroxyl (ca. 1200 wt.ppm) and low-hydroxyl (ca. 130 wt.ppm)-containing silica glasses in the temperature range of 900-1150 °C was investigated. Although the theoretical curve with a hydroxyl-concentration-independent diffusion coefficient deviates from the experimental curve, the diffusion coefficients obtained by fitting to the experimental results by the least squares method coincided with the “effective diffusion coefficients” in the literature, which were obtained from the total absorption change in the IR absorption peak for the hydroxyl group using thin samples. By the analysis considering the hydroxyl concentration dependence of the diffusion coefficient, we showed that the diffusion coefficient is proportional to hydroxyl concentration at each temperature, which is consistent with the model of the diffusion: SiOSi + H2O = 2SiOH. On the basis of this scheme, we tried to evaluate the diffusion coefficients of molecular water using equilibrium constant in the literature.

  13. A theoretical study of O2 activation by the Au7-cluster on Mg(OH)2: roles of surface hydroxyls and hydroxyl defects.

    PubMed

    Jia, Chuanyi; Fan, Weiliu

    2015-11-11

    Using density functional theory (DFT) calculations, we investigated O2 activation by the Au7-cluster supported on the perfect and hydroxyl defective Mg(OH)2(0001) surface. It is revealed that hydroxyl groups on the perfect Mg(OH)2(0001) surface can not only enhance the stability of the Au7-cluster, but also help the adsorption of the O2 molecule through hydrogen-bonding interactions with the 2nd-layered interfacial Au sites. Density of states (DOS) analysis shows that the d-band centers of the 2nd-layered interfacial Au atoms are very close to the Fermi level, which thereby reduce the Pauli repulsion and promote the O2 adsorption. These two responses make the 2nd-layered interfacial Au atoms favor O2 activation. Interestingly, the surface hydrogen atoms activated by the 1st-layered Au atoms can facilitate the O2 dissociation process as well. Such a process is dynamically favorable and more inclined to occur at low temperatures compared to the direct dissociation process. Meanwhile, the hydroxyl defects of Mg(OH)2(0001) located right under the Au7-cluster can also up-shift the d-band centers of the surrounding Au atoms toward the Fermi level, enhancing its catalytic activity for O2 dissociation. In contrast, the d-band center of Au atoms surrounding the hydroxyl defect near the Au7-cluster exhibits an effective down-shift to lower energies, and therefore holds low activity. These results unveiled the roles of surface hydroxyls and hydroxyl defects on the Au/Mg(OH)2 catalyst in O2 activation and could provide a theoretical guidance for chemists to efficiently synthesize Au/hydroxide catalysts. PMID:26529519

  14. Tuning magnetic splitting of zigzag graphene nanoribbons by edge functionalization with hydroxyl groups

    SciTech Connect

    Zhang, Huizhen; Yang, Haifang; Li, Lin; Fu, Huixia; Ma, Wei; Niu, Chunyao; Sun, Jiatao; Meng, Sheng; Gu, Changzhi

    2015-03-21

    The electronic properties and relative stability of zigzag graphene nanoribbons are studied by varying the percentage of hydroxyl radicals for edge saturation using first principle calculations. The passivated structures of zigzag graphene nanoribbon have spin-polarized ground state with antiferromagnetic exchange coupling across the edge and ferromagnetic coupling along the edges. When the edges are specially passivated by hydroxyl, the potentials of spin exchange interaction across the two edges shift accordingly, resulting into a spin-semiconductor. Varying the concentration of hydroxyl groups can alter the maximum magnetization splitting. When the percentage of asymmetrically adsorbed hydroxyl reaches 50%, the magnetization splitting can reach a value as high as 275 meV due to the asymmetrical potential across the nanoribbon edges. These results would favor spintronic device applications based on zigzag graphene nanoribbons.

  15. Spectral Response and Diagnostics of Biological Activity of Hydroxyl-Containing Aromatic Compounds

    NASA Astrophysics Data System (ADS)

    Tolstorozhev, G. B.; Mayer, G. V.; Bel'kov, M. V.; Shadyro, O. I.

    2016-08-01

    Using IR Fourier spectra and employing quantum-chemical calculations of electronic structure, spectra, and proton-acceptor properties, synthetic derivatives of aminophenol exhibiting biological activity in the suppression of herpes, influenza, and HIV viruses have been investigated from a new perspective, with the aim of establishing the spectral response of biological activity of the molecules. It has been experimentally established that the participation of the aminophenol hydroxyl group in intramolecular hydrogen bonds is characteristic of structures with antiviral properties. A quantum-chemical calculation of the proton-acceptor ability of the investigated aminophenol derivatives has shown that biologically active structures are characterized by a high proton-acceptor ability of oxygen of the hydroxyl group. A correlation that has been obtained among the formation of an intramolecular hydrogen bond, high proton-acceptor ability, and antiviral activity of substituted aminophenols enables us to predict the pharmacological properties of new medical preparations of the given class of compounds.

  16. Entropy Loss of Hydroxyl Groups of Balanol upon Binding to Protein Kinase A

    NASA Astrophysics Data System (ADS)

    Gidofalvi, Gergely; Wong, Chung F.; McCammon, J. Andrew

    2002-09-01

    This article describes a short project for an undergraduate to learn several techniques for computer-aided drug design. The project involves estimating the loss of the rotational entropy of the hydroxyl groups of balanol upon its binding to the enzyme protein kinase A (PKA), as the entropy loss can significantly influence PKA balanol binding affinity. This work employs semiempirical quantum mechanical techniques for estimating the potential energy curves for the rotation of the hydroxyl groups of balanol in vacuum and in PKA, and solves the Poisson equation to correct the potential energy curves for hydration effects. Statistical mechanical principles are then applied to estimate the desired entropy loss from the potential energy curves. The analysis examines the influence of hydration effects on the rotational preference of the hydroxyl groups and the significance of the rotational entropy in determining binding affinity.

  17. Oxime ether lipids containing hydroxylated head groups are more superior siRNA delivery agents than their nonhydroxylated counterparts

    PubMed Central

    Gupta, Kshitij; Mattingly, Stephanie J; Knipp, Ralph J; Afonin, Kirill A; Viard, Mathias; Bergman, Joseph T; Stepler, Marissa; Nantz, Michael H; Puri, Anu; Shapiro, Bruce A

    2015-01-01

    Aim: To evaluate the structure–activity relationship of oxime ether lipids (OELs) containing modifications in the hydrophobic domains (chain length, degree of unsaturation) and hydrophilic head groups (polar domain hydroxyl groups) toward complex formation with siRNA molecules and siRNA delivery efficiency of resulting complexes to a human breast cancer cell line (MDA-MB-231). Materials & methods: Ability of lipoplex formation between oxime ether lipids with nucleic acids were examined using biophysical techniques. The potential of OELs to deliver nucleic acids and silence green fluorescent protein (GFP) gene was analyzed using MDA-MB-231 and MDA-MB-231/GFP cells, respectively. Results & conclusion: Introduction of hydroxyl groups to the polar domain of the OELs and unsaturation into the hydrophobic domain favor higher transfection and gene silencing in a cell culture system. PMID:26107486

  18. Alkyne Ligation Handles: Propargylation of Hydroxyl, Sulfhydryl, Amino, and Carboxyl Groups via the Nicholas Reaction.

    PubMed

    Wells, Sarah M; Widen, John C; Harki, Daniel A; Brummond, Kay M

    2016-09-16

    The Nicholas reaction has been applied to the installation of alkyne ligation handles. Acid-promoted propargylation of hydroxyl, sulfhydryl, amino, and carboxyl groups using dicobalt hexacarbonyl-stabilized propargylium ions is reported. This method is useful for introduction of propargyl groups into base-sensitive molecules, thereby expanding the toolbox of methods for the incorporation of alkynes for bio-orthogonal reactions. High-value molecules are used as the limiting reagent, and various propargylium ion precursors are compared. PMID:27570975

  19. Hydroxylation of p-substituted phenols by tyrosinase: Further insight into the mechanism of tyrosinase activity

    SciTech Connect

    Munoz-Munoz, Jose Luis; Berna, Jose; Garcia-Molina, Maria del Mar; Garcia-Molina, Francisco; Garcia-Ruiz, Pedro Antonio; Varon, Ramon [Departamento de Quimica-Fisica, Escuela de Ingenieros Industriales de Albacete, Universidad de Castilla la Mancha, Avda. Espana s and others

    2012-07-27

    Highlights: Black-Right-Pointing-Pointer The action the copper complexes and tyrosinase on phenols is equivalent. Black-Right-Pointing-Pointer Isotope effect showed that nucleophilic attack to copper atom may be the slower step. Black-Right-Pointing-Pointer The value of {rho} (Hammett constant) supports an electrophilic aromatic substitution. Black-Right-Pointing-Pointer Data obtained in steady state pH 7 conditions support the mechanism of Scheme 1SM. -- Abstract: A study of the monophenolase activity of tyrosinase by measuring the steady state rate with a group of p-substituted monophenols provides the following kinetic information: k{sub cat}{sup m} and the Michaelis constant, K{sub M}{sup m}. Analysis of these data taking into account chemical shifts of the carbon atom supporting the hydroxyl group ({delta}) and {sigma}{sub p}{sup +}, enables a mechanism to be proposed for the transformation of monophenols into o-diphenols, in which the first step is a nucleophilic attack on the copper atom on the form E{sub ox} (attack of the oxygen of the hydroxyl group of C-1 on the copper atom) followed by an electrophilic attack (attack of the hydroperoxide group on the ortho position with respect to the hydroxyl group of the benzene ring, electrophilic aromatic substitution with a reaction constant {rho} of -1.75). These steps show the same dependency on the electronic effect of the substituent groups in C-4. Furthermore, a study of a solvent deuterium isotope effect on the oxidation of monophenols by tyrosinase points to an appreciable isotopic effect. In a proton inventory study with a series of p-substituted phenols, the representation of k{sub cat}{sup f{sub n}}/k{sub cat}{sup f{sub 0}} against n (atom fractions of deuterium), where k{sub cat}{sup f{sub n}} is the catalytic constant for a molar fraction of deuterium (n) and k{sub cat}{sup f{sub 0}} is the corresponding kinetic parameter in a water solution, was linear for all substrates. These results indicate that

  20. Interaction of hydrogen with ZnO nanopowders--evidence of hydroxyl group formation.

    PubMed

    Wong, Kester W J; Field, Matthew R; Ou, Jian Zhen; Latham, Kay; Spencer, Michelle J S; Yarovsky, Irene; Kalantar-zadeh, Kourosh

    2012-01-13

    There have been many investigations to reveal the nature of the hydrogen gas and ZnO nanopowder interaction at elevated temperatures, while at present no conclusive description of such an interaction has been confidently reported. In this work, we demonstrate that a hydroxyl group is formed during this interaction, depending on size and relative crystallinity of nanopowders. Our in situ Raman spectroscopy investigations show that the interaction directly affects the intensity of the Raman signal at 483 cm(-1), relative to the peak at 519 cm(-1). Ex situ x-ray diffraction (XRD) and infrared spectroscopy also show extra peaks at 44° and 1618 cm(-1), respectively, after hydrogenation. These peaks were all identified as surface hydroxyl groups, which can be related to the formation of water on the ZnO nanopowder surfaces.

  1. Biosynthesis of polyhydroxyalkanoates containing hydroxyl group from glycolate in Escherichia coli.

    PubMed

    Insomphun, Chayatip; Kobayashi, Shingo; Fujiki, Tetsuya; Numata, Keiji

    2016-12-01

    Polyhydroxyalkanoates (PHAs) containing hydroxyl groups in a side chain were produced in recombinant Escherichia coli JM109 using glycolate as the sole carbon source. The propionate-CoA transferase (pct) gene from Megasphaera elsdenii and the β-ketothiolase (bktB) gene and phaCAB operon from Ralstonia eutropha H16 were introduced into E. coli JM109. A novel monomer containing a hydroxyl group, dihydroxybutyrate (DHBA), was the expected product of the condensation of glycolyl-CoA and acetyl-CoA by BktB. The recombinant strain produced a PHA containing 1 mol% DHBA. The incorporation of DHBA may have been restricted because the expression of phaAB1 competes for acetyl-CoA. The PHA containing DHBA units were evaluated regarding thermal properties, such as melting temperature, glass transition temperature and thermal degradation temperature. The current study demonstrates a potential use of PHA containing hydroxyl groups as renewable resources in biological materials. PMID:27075993

  2. Development of a group contribution method to predict aqueous phase hydroxyl radical (HO*) reaction rate constants.

    PubMed

    Minakata, Daisuke; Li, Ke; Westerhoff, Paul; Crittenden, John

    2009-08-15

    The hydroxyl radical (HO*) is a strong oxidant that reacts with electron-rich sites of organic compounds and initiates complex chain mechanisms. In order to help understand the reaction mechanisms, a rule-based model was previously developed to predict the reaction pathways. For a kinetic model, there is a need to develop a rate constant estimator that predicts the rate constants for a variety of organic compounds. In this study, a group contribution method (GCM) is developed to predict the aqueous phase HO* rate constants for the following reaction mechanisms: (1) H-atom abstraction, (2) HO* addition to alkenes, (3) HO* addition to aromatic compounds, and (4) HO* interaction with sulfur (S)-, nitrogen (N)-, or phosphorus (P)-atom-containing compounds. The GCM hypothesizes that an observed experimental rate constant for a given organic compound is the combined rate of all elementary reactions involving HO*, which can be estimated using the Arrhenius activation energy, E(a), and temperature. Each E(a) for those elementary reactions can be comprised of two parts: (1) a base part that includes a reactive bond in each reaction mechanism and (2) contributions from its neighboring functional groups. The GCM includes 66 group rate constants and 80 group contribution factors, which characterize each HO* reaction mechanism with steric effects of the chemical structure groups and impacts of the neighboring functional groups, respectively. Literature-reported experimental HO* rate constants for 310 and 124 compounds were used for calibration and prediction, respectively. The genetic algorithms were used to determine the group rate constants and group contribution factors. The group contribution factors for H-atom abstraction and HO* addition to the aromatic compounds were found to linearly correlate with the Taft constants, sigma*, and electrophilic substituent parameters, sigma+, respectively. The best calibrations for 83% (257 rate constants) and predictions for 62% (77

  3. Chemoenzymatic collective synthesis of optically active hydroxyl(methyl)tetrahydronaphthalene-based bioactive terpenoids.

    PubMed

    Batwal, Ramesh U; Argade, Narshinha P

    2015-12-14

    Starting from succinic anhydride and 2-methylanisole, a chemoenzymatic collective formal/total synthesis of several optically active tetrahydronaphthalene based bioactive natural products has been presented via advanced level common precursors; the natural product and antipode (-)/(+)-aristelegone B. Regioselective benzylic oxidations, stereoselective introduction of hydroxyl groups at the α-position of ketone moiety in syn-orientation, efficient enzymatic resolutions with high enantiomeric purity, stereoselective reductions, samarium iodide induced deoxygenations and tandem acylation-Wittig reactions without racemization and/or eliminative aromatization were the key features. An attempted diastereoselective synthesis of (±)-vallapin has also been described.

  4. A functionalizable polyester with free hydroxyl groups and tunable physiochemical and biological properties

    PubMed Central

    You, Zhengwei; Cao, Haiping; Gao, Jin; Shin, Paul H.; Day, Billy W.; Wang, Yadong

    2010-01-01

    Polyesters with free functional groups allow facile modifications with biomolecules, which can lead to versatile biomaterials that afford controlled interactions with cells and tissues. Efficient synthesis of functionalizable polyesters is still a challenge that greatly limits the availability and widespread applications of biofunctionalized synthetic polymers. Here we report a simple route to prepare a functionalizable polyester, poly(sebacoyl diglyceride) (PSeD) bearing free hydroxyl groups. The key synthetic step is an epoxide ring-opening polymerization, instead of the traditional polycondensation, that produces poly(glycerol sebacate) (PGS) [1]. PSeD has a more defined structure with mostly linear backbone, more free hydroxyl groups, higher molecular weight, and lower polydispersity than PGS. Crosslinking PSeD with sebacic acid yields a polymer five times tougher and more elastic than cured PGS. PSeD exhibits good cytocompatibility in vitro. Furthermore, functionalization by glycine proceeds with high efficiency. This versatile synthetic platform can offer a large family of biodegradable, functionalized polymers with tunable physiochemical and biological properties useful for a wide range of biomedical applications. PMID:20149441

  5. Inhibition of Pseudomonas aeruginosa Swarming Motility by 1-Naphthol and Other Bicyclic Compounds Bearing Hydroxyl Groups

    PubMed Central

    Oura, Hiromu; Tashiro, Yosuke; Toyofuku, Masanori; Ueda, Kousetsu; Kiyokawa, Tatsunori; Ito, Satoshi; Takahashi, Yurika; Lee, Seunguk; Nojiri, Hideaki; Nakajima-Kambe, Toshiaki; Uchiyama, Hiroo; Futamata, Hiroyuki

    2015-01-01

    Many bacteria convert bicyclic compounds, such as indole and naphthalene, to oxidized compounds, including hydroxyindoles and naphthols. Pseudomonas aeruginosa, a ubiquitous bacterium that inhabits diverse environments, shows pathogenicity against animals, plants, and other microorganisms, and increasing evidence has shown that several bicyclic compounds alter the virulence-related phenotypes of P. aeruginosa. Here, we revealed that hydroxyindoles (4- and 5-hydroxyindoles) and naphthalene derivatives bearing hydroxyl groups specifically inhibit swarming motility but have minor effects on other motilities, including swimming and twitching, in P. aeruginosa. Further analyses using 1-naphthol showed that this effect is also associated with clinically isolated hyperswarming P. aeruginosa cells. Swarming motility is associated with the dispersion of cells from biofilms, and the addition of 1-naphthol maintained biofilm biomass without cell dispersion. We showed that this 1-naphthol-dependent swarming inhibition is independent of changes of rhamnolipid production and the intracellular level of signaling molecule cyclic-di-GMP (c-di-GMP). Transcriptome analyses revealed that 1-naphthol increases gene expression associated with multidrug efflux and represses gene expression associated with aerotaxis and with pyochelin, flagellar, and pilus synthesis. In the present study, we showed that several bicyclic compounds bearing hydroxyl groups inhibit the swarming motility of P. aeruginosa, and these results provide new insight into the chemical structures that inhibit the specific phenotypes of P. aeruginosa. PMID:25681177

  6. Inhibition of Pseudomonas aeruginosa swarming motility by 1-naphthol and other bicyclic compounds bearing hydroxyl groups.

    PubMed

    Oura, Hiromu; Tashiro, Yosuke; Toyofuku, Masanori; Ueda, Kousetsu; Kiyokawa, Tatsunori; Ito, Satoshi; Takahashi, Yurika; Lee, Seunguk; Nojiri, Hideaki; Nakajima-Kambe, Toshiaki; Uchiyama, Hiroo; Futamata, Hiroyuki; Nomura, Nobuhiko

    2015-04-01

    Many bacteria convert bicyclic compounds, such as indole and naphthalene, to oxidized compounds, including hydroxyindoles and naphthols. Pseudomonas aeruginosa, a ubiquitous bacterium that inhabits diverse environments, shows pathogenicity against animals, plants, and other microorganisms, and increasing evidence has shown that several bicyclic compounds alter the virulence-related phenotypes of P. aeruginosa. Here, we revealed that hydroxyindoles (4- and 5-hydroxyindoles) and naphthalene derivatives bearing hydroxyl groups specifically inhibit swarming motility but have minor effects on other motilities, including swimming and twitching, in P. aeruginosa. Further analyses using 1-naphthol showed that this effect is also associated with clinically isolated hyperswarming P. aeruginosa cells. Swarming motility is associated with the dispersion of cells from biofilms, and the addition of 1-naphthol maintained biofilm biomass without cell dispersion. We showed that this 1-naphthol-dependent swarming inhibition is independent of changes of rhamnolipid production and the intracellular level of signaling molecule cyclic-di-GMP (c-di-GMP). Transcriptome analyses revealed that 1-naphthol increases gene expression associated with multidrug efflux and represses gene expression associated with aerotaxis and with pyochelin, flagellar, and pilus synthesis. In the present study, we showed that several bicyclic compounds bearing hydroxyl groups inhibit the swarming motility of P. aeruginosa, and these results provide new insight into the chemical structures that inhibit the specific phenotypes of P. aeruginosa. PMID:25681177

  7. Hydration of hydroxyl and amino groups examined by molecular dynamics and neutron scattering.

    PubMed

    Hladílková, Jana; Fischer, Henry E; Jungwirth, Pavel; Mason, Philip E

    2015-05-28

    Neutron diffraction with isotopic substitution was performed on aqueous solutions of isopropyl alcohol and isopropylamine. The difference between these two measurements primarily contains information about the different hydration of the alcohol and amino group. This data is used as a test of the accuracy of molecular dynamic simulations of the same systems. Having established the level of accuracy of the modeling, it is employed as an interpretive tool for the experimental data. Even though the alcohol and the amine possess comparable hydrogen bonding capabilities, consisting respectively of either two hydrogen bond acceptors and one donor, or two hydrogen bond donors and one acceptor, we find significant differences in the hydration of the hydroxyl and amino groups.

  8. Water growth on metals and oxides: binding, dissociation and role of hydroxyl groups

    SciTech Connect

    Salmeron, M.; Bluhm, H.; Tatarkhanov, M.; Ketteler, G.; Shimizu, T.K.; Mugarza, A.; Deng, Xingyi; Herranz, T.; Yamamoto, S.; Nilsson, A.

    2008-09-01

    The authors discuss the role of the presence of dangling H bonds from water or from surface hydroxyl species on the wetting behavior of surfaces. Using Scanning Tunneling and Atomic Force Microscopies, and Photoelectron Spectroscopy, they have examined a variety of surfaces, including mica, oxides, and pure metals. They find that in all cases, the availability of free, dangling H-bonds at the surface is crucial for the subsequent growth of wetting water films. In the case of mica electrostatic forces and H-bonding to surface O atoms determine the water orientation in the first layer and also in subsequent layers with a strong influence in its wetting characteristics. In the case of oxides like TiO{sub 2}, Cu{sub 2}O, SiO{sub 2} and Al{sub 2}O{sub 3}, surface hydroxyls form readily on defects upon exposure to water vapor and help nucleate the subsequent growth of molecular water films. On pure metals, such as Pt, Pd, and Ru, the structure of the first water layer and whether or not it exhibits dangling H bonds is again crucial. Dangling H-bonds are provided by molecules with their plane oriented vertically, or by OH groups formed by the partial dissociation of water. By tying the two II atoms of the water molecules into strong H-bonds with pre-adsorbed O on Ru can also quench the wettability of the surface.

  9. IDENTIFICATION AND QUANTIFICATION OF AEROSOL POLAR OXYGENATED COMPOUNDS BEARING CARBOXYLIC AND/OR HYDROXYL GROUPS. 1. METHOD DEVELOPMENT

    EPA Science Inventory

    In this study, a new analytical technique was developed for the identification and quantification of multi-functional compounds containing simultaneously at least one hydroxyl or one carboxylic group, or both. This technique is based on derivatizing first the carboxylic group(s) ...

  10. Facile synthesis and characterization of novel biodegradable amphiphilic block copolymers bearing pendant hydroxyl groups.

    PubMed

    Hu, Gaicen; Fan, Xiaoshan; Xu, Bingcan; Zhang, Delong; Hu, Zhiguo

    2014-10-01

    Novel amphiphilic block copolymers bearing pendant hydroxyl groups polylactide-b-poly(3,3-bis(Hydroxymethyl-triazolylmethyl) oxetane)-b-polylactide (PLA-b-PHMTYO-b-PLA) were synthesized via a facile and efficient method. First, the block copolymer intermediates polylactide-b-poly(3,3-Diazidomethyloxetane)-b-polylactide (PLA-b-PBAMO-b-PLA) were synthesized through ring-opening polymerization of lactide using PBAMO as a macroinitiator. Following "Click" reaction of PLA-b-PBAMO-b-PLA with propargyl alcohol provided the targeted amphiphilic block copolymers PLA-b-PHMTYO-b-PLA with pendant hydroxyl groups. The composition and structure of prepared copolymers were characterized by (1)H nuclear magnetic resonance ((1)H NMR) spectroscopy, Fourier transform infrared (FT-IR) and gel permeation chromatography (GPC). The self-assembly behavior of the copolymers in water was investigated by transmission electron microscope (TEM), dynamic light scattering (DLS) and static light scattering (SLS). The results showed that the novel copolymers PLA-b-PHMTYO-b-PLA self-assembled into spherical micelles with diameters ranging from 100 nm to 200 nm in aqueous solution. These copolymers also exhibited low critical micellar concentrations (CMC: 6.9 × 10(-4)mg/mL and 3.9 × 10(-5)mg/mL, respectively). In addition, the in vitro cytotoxicity of these copolymers was determined in the presence of L929 cells. The results showed that the block copolymers PLA-b-PHMTYO-b-PLA exhibited better biocompatibility. Therefore, these well-defined copolymers are expected to find some applications in drug delivery or tissue engineering. PMID:25175206

  11. Facile synthesis and characterization of novel biodegradable amphiphilic block copolymers bearing pendant hydroxyl groups.

    PubMed

    Hu, Gaicen; Fan, Xiaoshan; Xu, Bingcan; Zhang, Delong; Hu, Zhiguo

    2014-10-01

    Novel amphiphilic block copolymers bearing pendant hydroxyl groups polylactide-b-poly(3,3-bis(Hydroxymethyl-triazolylmethyl) oxetane)-b-polylactide (PLA-b-PHMTYO-b-PLA) were synthesized via a facile and efficient method. First, the block copolymer intermediates polylactide-b-poly(3,3-Diazidomethyloxetane)-b-polylactide (PLA-b-PBAMO-b-PLA) were synthesized through ring-opening polymerization of lactide using PBAMO as a macroinitiator. Following "Click" reaction of PLA-b-PBAMO-b-PLA with propargyl alcohol provided the targeted amphiphilic block copolymers PLA-b-PHMTYO-b-PLA with pendant hydroxyl groups. The composition and structure of prepared copolymers were characterized by (1)H nuclear magnetic resonance ((1)H NMR) spectroscopy, Fourier transform infrared (FT-IR) and gel permeation chromatography (GPC). The self-assembly behavior of the copolymers in water was investigated by transmission electron microscope (TEM), dynamic light scattering (DLS) and static light scattering (SLS). The results showed that the novel copolymers PLA-b-PHMTYO-b-PLA self-assembled into spherical micelles with diameters ranging from 100 nm to 200 nm in aqueous solution. These copolymers also exhibited low critical micellar concentrations (CMC: 6.9 × 10(-4)mg/mL and 3.9 × 10(-5)mg/mL, respectively). In addition, the in vitro cytotoxicity of these copolymers was determined in the presence of L929 cells. The results showed that the block copolymers PLA-b-PHMTYO-b-PLA exhibited better biocompatibility. Therefore, these well-defined copolymers are expected to find some applications in drug delivery or tissue engineering.

  12. Photoremovable hydroxyl group protection. Use of the p-tolylsulfonyl protecting group in. beta. -disaccharide synthesis

    SciTech Connect

    Binkley, R.W.; Koholic, D.J. )

    1989-07-21

    The p-tolylsulfonyl group has been shown to a photoremovable group effective for protection of carbohydrates during disaccharide synthesis. The formation of the versatile, p-tolylsulfonyl-protected disaccharide 13 (methyl 3-O-(4-O-benzoyl-3-O-benzyl-2,6-dideoxy-{beta}-D-arabino-hexopyranosyl)-2,6-dideoxy-4-O-(p-tolylsulfonyl)-{alpha}-D-arabino-hexopyranoside) was accomplished by silver silicate catalyzed coupling of methyl 2,6-dideoxy-4-O-(p-tolylsulfonyl)-{alpha}-D-arabino-hexopyranoside (7) with 4-O-benzyl-2,6-dideoxy-{alpha}-D-arabino-hexopyranosyl bromide (8). Each of the three protecting groups (benzyl, benzoyl, and p-tolylsulfonyl) present in 13 was removed regioselectively under nonacidic conditions.

  13. A single tyrosine hydroxyl group almost entirely controls the NADPH specificity of Plasmodium falciparum ferredoxin-NADP+ reductase.

    PubMed

    Baroni, Sara; Pandini, Vittorio; Vanoni, Maria Antonietta; Aliverti, Alessandro

    2012-05-01

    Plasmodium falciparum ferredoxin-NADP(+) reductase (FNR) is a FAD-containing enzyme that, in addition to be a promising target of novel antimalarial drugs, represents an excellent model of plant-type FNRs. The cofactor specificity of FNRs depends on differences in both k(cat) and K(m) values for NADPH and NADH. Here, we report that deletion of the hydroxyl group of the conserved Y258 of P. falciparum FNR, which interacts with the 2'-phosphate group of NADPH, selectively decreased the k(cat) of the NADPH-dependent reaction by a factor of 2 to match that of the NADH-dependent one. Rapid-reaction kinetics, active-site titrations with NADP(+), and anaerobic photoreduction experiments indicated that this effect may be the consequence of destabilization of the catalytically competent conformation of bound NADPH. Moreover, because the Y258F replacement increased the K(m) for NADPH 4-fold and decreased that for NADH 3-fold, it led to a drop in the ability of the enzyme to discriminate between the coenzymes from 70- to just 1.5-fold. The impact of the Y258F change was not affected by the presence of the H286Q mutation, which is known to enhance the catalytic activity of the enzyme. Our data highlight the major role played by the Y258 hydroxyl group in determining the coenzyme specificity of P. falciparum FNR. From the general standpoint of engineering the kinetic properties of plant-type FNRs, although P. falciparum FNR is less strictly NADPH-dependent than its homologues, the almost complete abolishment of coenzyme selectivity reported here has never been accomplished before through a single mutation.

  14. Inhibitory activity of flavonoids from Prunus davidiana and other flavonoids on total ROS and hydroxyl radical generation.

    PubMed

    Jung, Hyun Ah; Jung, Mee Jung; Kim, Ji Young; Chung, Hae Young; Choi, Jae Sue

    2003-10-01

    Since reactive oxygen species (ROS) and hydroxyl radicals (*OH) play an important role in the pathogenesis of many human degenerative diseases, much attention has focused on the development of safe and effective antioxidants. Preliminary experiments have revealed that the methanol (MeOH) extract of the stem of Prunus davidiana exerts inhibitory/scavenging activities on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, total ROS and peroxynitrites (ONOO-). In the present study, the antioxidant activities of this MeOH extract and the organic solvent-soluble fractions, dichloromethane (CH2Cl2), ethyl acetate (EtOAc), and n-butanol (n-BuOH), and the water layer of P. davidiana stem were evaluated for the potential to inhibit *OH and total ROS generation in kidney homogenates using 2',7'-dichlorodihydrofluorescein diacetate (DCHF-DA), and for the potential to scavenge authentic ONOO-. We also evaluated the inhibitory activity of seven flavonoids isolated from P. davidiana stem, kaempferol, kaempferol 7-O-beta-D-glucoside, (+)-catechin, dihydrokaempferol, hesperetin 5-O-beta-D-glucoside, naringenin and its 7-O-beta-D-glucoside, on the total ROS, *OH and ONOO- systems. For the further elucidation of the structure-inhibitory activity relationship of flavonoids on total ROS and *OH generation, we measured the antioxidant activity of sixteen flavonoids available, including three active flavonoids isolated from P. davidiana, on the total ROS and *OH systems. We found that the inhibitory activity on total ROS generation increases in strength with more numerous hydroxyl groups on their structures. Also, the presence of an ortho-hydroxyl group, whether on the A-ring or B-ring, and a 3-hydroxyl group on the C-ring increased the inhibitory activity on both total ROS and *OH generation.

  15. Hydroxyl radical scavenging activities of isoquinoline alkaloids isolated from Coptis chinensis.

    PubMed

    Jang, Moon Hee; Kim, Hyun Young; Kang, Ki Sung; Yokozawa, Takako; Park, Jeong Hill

    2009-03-01

    The hydroxyl radical (*OH) scavenging and ferrous ion chelating activities of four isoquinoline alkaloids isolated from Coptis chinensis Franch were studied for the identification of their structural characteristics to scavenge *OH. The *OH was generated via Fe(II)-catalazed Fenton reaction in this study and the reliable measurement of *OH scavenging activities of isoquinoline alkaloids were achieved using electron spin resonance (ESR) spectrometry method. At the 1 mM concentration, berberrubine (85%) showed the strongest *OH scavenging activity and the next were in the decreasing order of coptisine (79%), berberine (23%), and palmatine (22%). The ferrous ion chelating effects of the alkaloids showed similar pattern with their *OH scavenging effects. These results suggest that *OH scavenging effects of the alkaloids were closely related to their ferrous ion chelating activities. In addition, metal chelating functional groups such as hydroxy group at C-9 and methylenedioxy group at C-9 and C-10 were thought to contribute to the *OH scavenging activities of the isoquinoline alkaloids.

  16. Conformational influence of the ribose 2'-hydroxyl group: crystal structures of DNA-RNA chimeric duplexes

    NASA Technical Reports Server (NTRS)

    Egli, M.; Usman, N.; Rich, A.

    1993-01-01

    We have crystallized three double-helical DNA-RNA chimeric duplexes and determined their structures by X-ray crystallography at resolutions between 2 and 2.25 A. The two self-complementary duplexes [r(G)d(CGTATACGC)]2 and [d(GCGT)r(A)d(TACGC)]2, as well as the Okazaki fragment d(GGGTATACGC).r(GCG)d(TATACCC), were found to adopt A-type conformations. The crystal structures are non-isomorphous, and the crystallographic environments for the three chimeras are different. A number of intramolecular interactions of the ribose 2'-hydroxyl groups contribute to the stabilization of the A-conformation. Hydrogen bonds between 2'-hydroxyls and 5'-oxygens or phosphate oxygens, in addition to the previously observed hydrogen bonds to 1'-oxygens of adjacent riboses and deoxyriboses, are observed in the DNA-RNA chimeric duplexes. The crystalline chimeric duplexes do not show a transition between the DNA A- and B-conformations. CD spectra suggest that the Okazaki fragment assumes an A-conformation in solution as well. In this molecule the three RNA residues may therefore lock the complete decamer in the A-conformation. Crystals of an all-DNA strand with the same sequence as the self-complementary chimeras show a morphology which is different from those of the chimera crystals. Moreover, the oligonucleotide does not match any of the sequence characteristics of DNAs usually adopting the A-conformation in the crystalline state (e.g., octamers with short alternating stretches of purines and pyrimidines). In DNA-RNA chimeric duplexes, it is therefore possible that a single RNA residue can drive the conformational equilibrium toward the A-conformation.

  17. Different hydroxyl radical scavenging activity of water-soluble beta-alanine C60 adducts.

    PubMed

    Sun, Tao; Jia, Zhishen; Xu, Zhude

    2004-04-01

    Three C(60) derivatives [C(60) (NHCH(2)CH(2)COONa)(n)(H)(n)], n=1, 5, 9] (A, B, C) with different additional number of beta-alanine were synthesized by the control of relative amount of C(60) and beta-alanine added. Hydroxyl radical scavenging activity of the adducts was evaluated in a copper-catalyzed Haber-Weiss reaction by chemiluminescence technology. The 50% inhibition concentrations (IC(50)'s) of A, B, and C were 147.2 micromol/L, 76.3 micromol/L, and 96.2 micromol/L, respectively. The difference should be closely related to the numbers of residual C=C bonds in C(60), steric effect and electron-withstanding effect of amino group especially.

  18. Production of hydroxyl radical by redox active flavonoids

    SciTech Connect

    Kalyanaraman, B.; Hodnick, W.F.; Pardini, R.S.

    1986-05-01

    The authors have previously shown that flavonoids autoxidize and generate superoxide (O/sub 2//sup -/) and hydrogen peroxide (H/sub 2/O/sub 2/), suggesting that hydroxyl radical (OH) could be formed via the metal-ion catalyzed Haber-Weiss reaction. In the presence of ethylenediamine tetraacetic acid (EDTA) and 5,5-dimethyl-1-pyrroline-1-oxide (DMPO), myricetin, quercetagetin and quercetin gave an ESR signal for the DMPO-OH spin adduct, and the DMPO-Eto adduct in the presence of excess ethanol, indicating the production of free OH. The addition of FeCl/sub 3/ to the reaction mixture resulted in a dramatic increase in the DMPO-OH signal. Without chelator (EDTA) there was no signal and the presence of diethylenetriamine-pentaacetic acid (DETAPAC) greatly diminished the signal. The presence of superoxide dismutase (SOD) had no effect on the signal while catalase completely abrogated the signal. The addition of Fe (III)-EDTA to flavonoid solutions under anaerobic conditions produced time dependent auxochromic shifts in their absorption spectra and resulted in the reduction of Fe (III) to Fe (II). These data suggest that the flavonoids autoxidize to produce O/sub 2//sup -/ and H/sub 2/O/sub 2/ by dismutation and in the presence of Fe (III)-EDTA the flavonoid can directly reduce the Fe (III) to Fe (II) resulting in the production of OH through Fenton chemistry.

  19. Photoluminescence of oxygen vacancies and hydroxyl group surface functionalized SnO2 nanoparticles.

    PubMed

    Bonu, Venkataramana; Das, Arindam; Amirthapandian, S; Dhara, Sandip; Tyagi, Ashok Kumar

    2015-04-21

    We report, for the first time, the luminescence property of the hydroxyl group surface functionalized quantum dots (QDs) and nanoparticles (NPs) of SnO2 using low energy excitations of 2.54 eV (488 nm) and 2.42 eV (514.5 nm). This luminescence is in addition to generally observed luminescence from 'O' defects. The as-prepared SnO2 QDs are annealed at different temperatures under ambient conditions to create NPs with varying sizes. Subsequently, the average size of the NPs is calculated from the acoustic vibrations observed at low frequencies in the Raman spectra and by the transmission electron microscopy measurements. Detailed photoluminescence studies with 3.815 eV (325 nm) excitation reveal the nature of in-plane and bridging 'O' vacancies as well as adsorption and desorption occurring at different annealing temperatures. X-ray photoelectron spectroscopy studies also support this observation. The defect level related to the surface -OH functional groups shows a broad luminescence peak at around 1.96 eV in SnO2 NPs which is elaborated using temperature dependent studies. PMID:25774472

  20. Stereospecificity in hydroxyl radical scavenging activities of four ginsenosides produced by heat processing.

    PubMed

    Kang, Ki Sung; Kim, Hyun Young; Yamabe, Noriko; Yokozawa, Takako

    2006-10-01

    The activity-guided fractionation of sun ginseng (SG, heat processed Panax ginseng C. A. Meyer at 120 degrees C) was carried out to identify its main active hydroxyl radical (*OH) scavenging components. As a result, the n-BuOH fraction mainly consisting of ginsenosides showed the strongest activity. Of several ginsenosides of SG, the *OH scavenging activities of relatively high contents of 20(S)-Rg(3), 20(R)-Rg(3), Rk(1), and Rg(5) were compared. Rg(5) and 20(S)-Rg(3) showed strong *OH scavenging IC(50) values of 0.15 and 0.44 mM, respectively, and these activities were prominently higher than each of their respective isomers. Therefore, stereospecificity exists in the *OH scavenging activities of ginsenosides produced by heat processing. Especially, the double bond at carbon-20(22) or the OH group at carbon-20 geometrically close to OH at carbon-12 is thought to increase the *OH scavenging activity of ginsenosides.

  1. Curable liquid hydrocarbon prepolymers containing hydroxyl groups and process for producing same

    NASA Technical Reports Server (NTRS)

    Rhein, R. A.; Ingham, J. D. (Inventor)

    1978-01-01

    Production of hydroxyl containing curable liquid hydrocarbon prepolymers by ozonizing a high molecular weight saturated hydrocarbon polymer such as polyisobutylene or ethylene propylene rubber is discussed. The ozonized material is reduced using reducing agents, preferably diisobutyl aluminum hydride, to form the hydroxyl containing liquid prepolymers having a substantially lower molecular weight than the parent polymer. The resulting curable liquid hydroxyl containing prepolymers can be poured into a mold and readily cured, with reactants such as toluene diisocyanate, to produce highly stable elastomers having a variety of uses such as binders for solid propellants.

  2. Catalytic activity of unsaturated coordinated Cu-MOF to the hydroxylation of phenol

    NASA Astrophysics Data System (ADS)

    Jian, Lijuan; Chen, Chao; Lan, Fan; Deng, Shengjun; Xiao, Weiming; Zhang, Ning

    2011-05-01

    A 2D metal-organic framework [Cu 2 (BPTC) (Im) 4(H 2O) (DMF)] n ( 1) with unsaturated coordinated Cu(II) sites has been prepared under solvothermal condition, and applied to the hydroxylation of phenol after activating. The catalytic results indicate that 1a (the activated 1) exhibits an obvious activity for phenol hydroxylation at 40 °C for 4 h. Compared to the control experiments where the free Cu(II) (from Cu(OAc) 2 salt) has been utilized as the catalysts, 1a shows the higher selectivity to diphenols. This suggests that the coordinated environment of unsaturated coordinated Cu(II) sites in the 2D layer play the key role in the phenol hydroxylation.

  3. Enumeration of sugars and sugar alcohols hydroxyl groups by aqueous-based acetylation and MALDI-TOF mass spectrometry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A method is described for enumerating hydroxyl groups on analytes in aqueous media is described, and applied to some common polyalcohols (erythritol, mannitol, and xylitol) and selected carbohydrates. The analytes were derivatized in water with vinyl acetate in presence of sodium phosphate buffer. ...

  4. Synthesis and evaluation of lanthanide ion DOTA-tetraamide complexes bearing peripheral hydroxyl groups

    PubMed Central

    Pasha, Azhar; Lin, Mai; Tircsó, Gyula; Rostollan, Cynthia L.; Woods, Mark; Kiefer, Garry E.; Sherry, A. Dean; Sun, Xiankai

    2009-01-01

    The use of lanthanide-based contrast agents for magnetic resonance imaging (MRI) has become an integral component of this important diagnostic modality. These inert chelates typically possess high thermodynamic stability constants that serve as a predictor for in vivo stability and low toxicity. Recently a new class of contrast agents was reported having a significantly lower degree thermodynamic stability while exhibiting biodistribution profiles indicative of high stability under biological conditions. These observations are suggestive that the nature of contrast agent stability is also dependent upon the kinetics of complex dissociation; a feature of potential importance when contemplating the design of new chelates for in vivo use. In this paper we present a study of the kinetics of acid catalyzed dissociation, thermodynamic stability, serum stability and biodistribution of a series of DOTA-tetraamide complexes that have been substituted with peripheral hydroxyl groups. The data indicate that these non-traditional contrast agents exhibit in vivo stability comparable to agents with much higher log KML values demonstrating the important contribution of kinetic inertness. PMID:19083028

  5. Black Hydroxylated Titanium Dioxide Prepared via Ultrasonication with Enhanced Photocatalytic Activity

    PubMed Central

    Fan, Chenyao; Chen, Chao; Wang, Jia; Fu, Xinxin; Ren, Zhimin; Qian, Guodong; Wang, Zhiyu

    2015-01-01

    The amorphous TiO2 derived from hydroxylation has become an effective approach for the enhancement of photocatalytic activity of TiO2 since a kind of special black TiO2 was prepared by engineering disordered layers on TiO2 nanocrystals via hydrogenation. In this contribution, we prepared totally amorphous TiO2 with various degrees of blackness by introducing hydroxyls via ultrasonic irradiation, through which can we remarkably enhance the photocatalytic activity of TiO2 with improved light harvesting and narrowed band gap. PMID:26133789

  6. Unique Phase Behaviors in the Gemini Surfactant/EAN Binary System: The Role of the Hydroxyl Group.

    PubMed

    Li, Qintang; Wang, Xudong; Yue, Xiu; Chen, Xiao

    2015-12-22

    The hydroxyl group in the spacer of a cationic Gemini surfactant (12-3OH-12) caused dramatic changes of the phase behaviors in a protic ionic liquid (EAN). Here, the effects of the hydroxyl group on micellization and lyotropic liquid crystal formation were investigated through the surface tension, small-angle X-ray scattering, polarized optical microscopy, and rheological measurements. With the hydroxyl group in the spacer, the critical micellization concentration of 12-3OH-12 was found to be lower than that of the homologue without hydroxyl (12-3-12) and the 12-3OH-12 molecules packed more densely at the air/EAN interface. It was then interesting to observe a coexistence of two separated phases at wide concentration and temperature ranges in this 12-3OH-12/EAN system. Such a micellar phase separation was rarely observed in the ionic surfactant binary system. With the increase of surfactant concentration, the reverse hexagonal and bicontinuous cubic phases appeared in sequence, whereas only a reverse hexagonal phase was found in 12-3-12/EAN system. But, the hexagonal phases formed with 12-3OH-12 exhibited lower viscoelasticity and thermostability than those observed in 12-3-12/EAN system. Such unique changes in phase behaviors of 12-3OH-12 were ascribed to their enhanced solvophilic interactions of 12-3OH-12 and relatively weak solvophobic interactions in EAN.

  7. Bacterial conversion of hydroxylamino aromatic compounds by both lyase and mutase enzymes involves intramolecular transfer of hydroxyl groups.

    PubMed

    Nadeau, Lloyd J; He, Zhongqi; Spain, Jim C

    2003-05-01

    Hydroxylamino aromatic compounds are converted to either the corresponding aminophenols or protocatechuate during the bacterial degradation of nitroaromatic compounds. The origin of the hydroxyl group of the products could be the substrate itself (intramolecular transfer mechanism) or the solvent water (intermolecular transfer mechanism). The conversion of hydroxylaminobenzene to 2-aminophenol catalyzed by a mutase from Pseudomonas pseudoalcaligenes JS45 proceeds by an intramolecular hydroxyl transfer. The conversions of hydroxylaminobenzene to 2- and 4-aminophenol by a mutase from Ralstonia eutropha JMP134 and to 4-hydroxylaminobenzoate to protocatechuate by a lyase from Comamonas acidovorans NBA-10 and Pseudomonas sp. strain 4NT were proposed, but not experimentally proved, to proceed by the intermolecular transfer mechanism. GC-MS analysis of the reaction products formed in H(2)(18)O did not indicate any (18)O-label incorporation during the conversion of hydroxylaminobenzene to 2- and 4-aminophenols catalyzed by the mutase from R. eutropha JMP134. During the conversion of 4-hydroxylaminobenzoate catalyzed by the hydroxylaminolyase from Pseudomonas sp. strain 4NT, only one of the two hydroxyl groups in the product, protocatechuate, was (18)O labeled. The other hydroxyl group in the product must have come from the substrate. The mutase in strain JS45 converted 4-hydroxylaminobenzoate to 4-amino-3-hydroxybenzoate, and the lyase in Pseudomonas strain 4NT converted hydroxylaminobenzene to aniline and 2-aminophenol but not to catechol. The results indicate that all three types of enzyme-catalyzed rearrangements of hydroxylamino aromatic compounds proceed via intramolecular transfer of hydroxyl groups.

  8. Prolyl 4-hydroxylase activity-responsive transcription factors: From hydroxylation to gene expression and neuroprotection

    PubMed Central

    Siddiq, Ambreena; Aminova, Leila R; Ratan, Rajiv R

    2008-01-01

    Most homeostatic processes including gene transcription occur as a result of deviations in physiological tone that threatens the survival of the organism. A prototypical homeostatic stress response includes changes in gene expression following alterations in oxygen, iron or 2-oxoglutarate levels. Each of these cofactors plays an important role in cellular metabolism. Accordingly, a family of enzymes known as the Prolyl 4-hydroxylase (PHD) enzymes are a group of dioxygenases that have evolved to sense changes in 2-oxoglutarate, oxygen and iron via changes in enzyme activity. Indeed, PHDs are a part of an established oxygen sensor system that regulates transcriptional regulation of hypoxia/stress-regulated genes and thus are an important component of events leading to cellular rescue from oxygen, iron or 2-oxoglutarate deprivations. The ability of PHD activity to regulate homeostatic responses to oxygen, iron or 2-oxoglutarate metabolism has led to the development of small molecule inhibitors of the PHDs as a strategy for activating or augmenting cellular stress responses. These small molecules are proving effective in preclinical models of stroke and Parkinson's disease. However the precise protective pathways engaged by PHD inhibition are only beginning to be defined. In the current review, we summarize the role of iron, 2-oxoglutarate and oxygen in the PHD catalyzed hydroxylation reaction and provide a brief discussion of some of the transcription factors that play an effective role in neuroprotection against oxidative stress as a result of changes in PHD activity. PMID:17981760

  9. Structure-guided unravelling: Phenolic hydroxyls contribute to reduction of acrylamide using multiplex quantitative structure-activity relationship modelling.

    PubMed

    Zhang, Yu; Huang, Mengmeng; Wang, Qiao; Cheng, Jun

    2016-05-15

    We reported a structure-activity relationship study on unravelling phenolic hydroxyls instead of alcoholic hydroxyls contribute to the reduction of acrylamide formation by flavonoids. The dose-dependent study shows a close correlation between the number of phenolic hydroxyls of flavonoids and their reduction effects. In view of positions of hydroxyls, the 3',4'(ortho)-dihydroxyls in B cycle, 3-hydroxyl or hydroxyls of 3-gallate in C cycle, and 5,7(meta)-dihydroxyls in A cycle of flavonoid structures play an important role in the reduction of acrylamide. Flavone C-glycosides are more effective at reducing the formation of acrylamide than flavone O-glycosides when sharing the same aglycone. The current multiplex quantitative structure-activity relationship (QSAR) equations effectively predict the inhibitory rates of acrylamide using selected chemometric parameters (R(2): 0.835-0.938). This pioneer study opens a broad understanding on the chemoprevention of acrylamide contaminants on a structural basis.

  10. Use of molecular dynamics to assess the biophysiological role of hydroxyl groups in glycerol dyalkyl glycerol teraethers

    NASA Astrophysics Data System (ADS)

    Huguet, Carme; Costenaro, Lionel; Fietz, Susanne; Daura, Xavier

    2015-04-01

    The cell membrane of some Archaea is constituted by lipids that span the whole membrane width and contain two alkyl chains bound by two glycerol groups (glycerol dyalkyl glycerol teraethers or GDGTs). These lipids confer stability to the membrane in mesophile to extremophile environments. Besides the more frequently studied isoprenoid archaeal lipids, both mono- and dihydroxy-GDGTs (OH-GDGT) have been recently reported to occur in marine sediments (1). OH-GDGTs contain up to two cyclopentane moieties and have been identified in both core and intact forms. In 2013, a correlation between OH-GDGTs and temperature was reported, with higher relative OH-GDGT abundances at high latitudes (2,3). The physiological function of the hydroxyl group in a GDGT is not yet known, but given the field results, it could be linked to an adaptation of the membrane to changes in temperature. For hydroxydiether lipid cores in methanogenic bacteria, it has been postulated that the hydroxyl group may alter the cell membrane properties: either extending the polar head group region or creating a hydrophilic pocket (4). It has also been suggested that the hydroxylation of the biphytany (l) moiety may result in enhanced membrane rigidity (1). To improve our understanding of the effect of the hydroxylation on physical properties of membranes, we performed molecular-dynamics simulations of GDGT membranes presenting and lacking these additional OH groups. This is an approach with a great development potential in the archaea lipid field, especially in relation to proxy validation. Our results indicate that the addition of an OH increases the membrane fluidity, thus providing an advantage in cold environments. We also observe a widening of the polar head group area, which could enhance transport. 1. Liu et al. 2012, GCA 2. Huguet et al. 2013, Org. Geochem 3. Fietz et al. 2013 4. Sprott et al. 1990. J. Biol. Chem. 265, 13735-13740.

  11. Oestradiol protects against the harmful effects of fluoride more by increasing thiol group levels than scavenging hydroxyl radicals.

    PubMed

    Dlugosz, Anna; Roszkowska, Anna; Zimmer, Mariusz

    2009-12-01

    The aim of the study was to investigate the role of oestrogens in free radical detoxication upon exposure to fluoride. Interactions between xenobiotics and oestrogens need to be investigated, especially as many chemicals interact with the oestrogen receptor. It is still unknown whether free radical-generating xenobiotics can influence the antioxidative ability of oestradiol (E(2)). In an in vitro examination of human placental mitochondria, thiobarbituric active reagent species (TBARS), hydroxyl radical ((*)OH) generation and protein thiol (-SH) groups were detected. 17beta-E(2) was examined in physiological (0.15-0.73 nM) and experimental (1-10 microM) concentrations and sodium fluoride (NaF) in concentrations of 6-24 microM. E(2) in all the concentrations significantly decreased lipid peroxidation measured as the TBARS level, in contrast to NaF, which increased lipid peroxidation. Lipid peroxidation induced by NaF was decreased by E(2). The influence of E(2) on (*)OH generation was not very significant and depended on the E(2 )concentration. The main mechanism of E(2) protection in NaF exposure appeared to be connected with the influence of E(2 )on thiol group levels, not (*)OH scavenging ability. The E(2) in concentrations 0.44-0.73 nM and 1-10 microM significantly increased the levels of -SH groups, in contrast to NaF, which significantly decreased them. E(2) at every concentration reversed the harmful effects of NaF on -SH group levels. No unfavourable interactions in the influence of E(2) and NaF on TBARS production, (*)OH generation, or -SH group levels were observed. The results suggest that postmenopausal women could be more sensitive to NaF-initiated oxidative stress.

  12. Potent and Selective Monoamine Oxidase-B Inhibitory Activity: Fluoro- vs. Trifluoromethyl-4-hydroxylated Chalcone Derivatives.

    PubMed

    Mathew, Bijo; Mathew, Githa Elizabeth; Uçar, Gülberk; Baysal, Ipek; Suresh, Jerad; Mathew, Sincy; Haridas, Abitha; Jayaprakash, Venkatesan

    2016-08-01

    For various neurodegenerative disorders like Alzheimer's and Parkinson's diseases, selective and reversible MAO-B inhibitors have a great therapeutic value. In our previous study, we have shown that a series of methoxylated chalcones with F functional group exhibited high binding affinity toward human monoamine oxidase-B (hMAO-B). In continuation of our earlier study and to extend the understanding of the structure-activity relationships, a series of five new chalcones were studied for their inhibition of hMAO. The results demonstrated that these compounds are reversible and selective hMAO-B inhibitors with a competitive mode of inhibition. The most active compound, (2E)-1-(4-hydroxyphenyl)-3-[4-(trifluoromethyl)phenyl]prop-2-en-1-one, exhibited a Ki value of 0.33 ± 0.01 μm toward hMAO-B with a selectivity index of 26.36. A molecular docking study revealed that the presence of a H-bond network in hydroxylated chalcone with the N(5) atom of FAD is crucial for MAO-B selectivity and potency.

  13. Synthesis of dendrigraft poly(ϵ-caprolactone)s using side hydroxyl groups for the grafting of branch chains.

    PubMed

    Cheng, Juan; Ling, Xiujun; Zhong, Zhenlin; Zhuo, Renxi

    2011-11-15

    Dendrigraft poly(ϵ-caprolactone)s with high molecular weight and narrow polydispersity are synthesized via a convenient generation-growth approach. Copolymerization of ϵ-caprolactone (CL) and 4-(2-benzoxyethoxy)-ϵ-caprolactone (BECL) with stannous octanoate as a catalyst affords a functionalized poly(ϵ-caprolactone) (PCL) with benzyl-protected hydroxyl side groups. After removal of benzyl groups by palladium-catalyzed hydrogenolysis, the graft copolymerization of CL and BECL onto the hydroxyl-bearing linear polyester (zero-generation) affords the first-generation graft polyester. Further deprotection and graft polymerization cycles led to dendrigraft polyesters. Molecular weights are multiplied in each graft copolymerization. The second-generation dendrigraft poly(ϵ-caprolactone) has an M(w) of 236 000 g·mol(-1) and M(w) /M(n) of 1.53. PMID:21928304

  14. Effect of hydroxyl group position on adsorption behavior and corrosion inhibition of hydroxybenzaldehyde Schiff bases: Electrochemical and quantum calculations

    NASA Astrophysics Data System (ADS)

    Danaee, I.; Ghasemi, O.; Rashed, G. R.; Rashvand Avei, M.; Maddahy, M. H.

    2013-03-01

    The corrosion inhibition and adsorption of N,N'-bis(n-hydroxybenzaldehyde)-1,3-propandiimine (n-HBP) Schiff bases has been investigated on steel electrode in 1 M HCl by using electrochemical techniques. The experimental results suggest that the highest inhibition efficiency was obtained for 3-HBP. Polarization curves reveal that all studied inhibitors are mixed type. Density functional theory (DFT) at the B3LYP/6-31G(d,p) and B3LYP/3-21G basis set levels and ab initio calculations using HF/6-31G(d,p) and HF/3-21G methods were performed on three Schiff bases. By studying the effects of hydroxyl groups in ortho-, meta-, para- positions, the best one as inhibitor was found to be meta-position of OH in Schiff base (i.e., 3-HBP). The order of inhibition efficiency obtained was corresponded with the order of most of the calculated quantum chemical parameters. Quantitative structure activity relationship (QSAR) approach has been used and a correlation of the composite index of some of the quantum chemical parameters was performed to characterize the inhibition performance of the Schiff bases studied. The results showed that %IE of the Schiff bases was closely related to some of the quantum chemical parameters but with varying degrees/order. The calculated %IE of the Schiff base studied was found to be close to their experimental corrosion inhibition efficiencies.

  15. Novel spectroscopic sensor for the hydroxyl radical scavenging activity measurement of biological samples.

    PubMed

    Bekdeşer, Burcu; Özyürek, Mustafa; Güçlü, Kubilay; Apak, Reşat

    2012-09-15

    A novel spectroscopic sensor was developed and validated for hydroxyl radical scavenging (HRS) activity estimation using terephthalate (TP) as probe. This sensor was designed by electrostatic immobilization of the chromogenic oxidizing agent of the CUPric Reducing Antioxidant Capacity (CUPRAC) method, Cu(II)-Neocuproine (Cu(II)-Nc) complex, on a Nafion cation-exchange membrane, and the spectrophotometric assay developed in aqueous-alcoholic solutions was integrated to the CUPRAC sensor. Hydroxyl radicals ((•)OH) generated from an equivalent mixture of Fe(II)+EDTA with hydrogen peroxide attacked both the probe and the (•)OH scavengers in 37 °C-incubated solutions for 1/2h. The HRS activity was measured using the decrease in CUPRAC absorbance at 450 nm - arising from the reduction of Cu(II)-Nc reagent to the Cu(I)-neocuproine chelate - of the hydroxylated probe (TP) undergoing radical attack in the presence of (•)OH scavengers. The HRS activity was evaluated as the second-order rate constants of biologically active compounds for (•)OH scavenging and also as the percentage scavenging of a measured compound or sample relative to a reference compound. Using this reaction, a kinetic approach was adopted to assess the HRS activity of amino acids, plasma- and thiol-antioxidants. This assay, applicable to small molecule antioxidants and tissue homogenates, proved to be efficient for serine and albumin for which the widely used TBARS (thiobarbituric acid-reactive substances) test is nonresponsive. Under optimal conditions, about half of the probe (TP) was converted into 2-hydroxyterephthalate (hTP), and this monohydroxylated derivative, being the only product of hydroxylation, was a more specific marker of (•)OH than the non-specific malondialdehyde end-product of the TBARS test. The sensor gave a linear response to scavenger concentration in the competition kinetic equation.

  16. Chemical engineering of the peptidyl transferase center reveals an important role of the 2′-hydroxyl group of A2451

    PubMed Central

    Erlacher, Matthias D.; Lang, Kathrin; Shankaran, Nisha; Wotzel, Brigitte; Hüttenhofer, Alexander; Micura, Ronald; Mankin, Alexander S.; Polacek, Norbert

    2005-01-01

    The main enzymatic reaction of the large ribosomal subunit is peptide bond formation. Ribosome crystallography showed that A2451 of 23S rRNA makes the closest approach to the attacking amino group of aminoacyl-tRNA. Mutations of A2451 had relatively small effects on transpeptidation and failed to unequivocally identify the crucial functional group(s). Here, we employed an in vitro reconstitution system for chemical engineering the peptidyl transferase center by introducing non-natural nucleosides at position A2451. This allowed us to investigate the peptidyl transfer reaction performed by a ribosome that contained a modified nucleoside at the active site. The main finding is that ribosomes carrying a 2′-deoxyribose at A2451 showed a compromised peptidyl transferase activity. In variance, adenine base modifications and even the removal of the entire nucleobase at A2451 had only little impact on peptide bond formation, as long as the 2′-hydroxyl was present. This implicates a functional or structural role of the 2′-hydroxyl group at A2451 for transpeptidation. PMID:15767286

  17. Hydrogen spillover enhanced hydroxyl formation and catalytic activity toward CO oxidation at the metal/oxide interface.

    PubMed

    Jin, Yuekang; Sun, Guanghui; Xiong, Feng; Ding, Liangbing; Huang, Weixin

    2015-03-01

    H2-promoted catalytic activity of oxide-supported metal catalysts in low-temperature CO oxidation is of great interest but its origin remains unknown. Employing an FeO(111)/Pt(111) inverse model catalyst, we herewith report direct experimental evidence for the spillover of H(a) adatoms on the Pt surface formed by H2 dissociation to the Pt-FeO interface to form hydroxyl groups that facilely oxidize CO(a) on the neighboring Pt surface to produce CO2. Hydroxyl groups and coadsorbed water play a crucial role in the occurrence of hydrogen spillover. These results unambiguously identify the occurrence of hydrogen spillover from the metal surface to the noble metal/metal oxide interface and the resultant enhanced catalytic activity of the metal/oxide interface in low-temperature CO oxidation, which provides a molecular-level understanding of both H2-promoted catalytic activity of metal/oxide ensembles in low-temperature CO oxidation and hydrogen spillover.

  18. Mucor hiemalis mediated 14α-hydroxylation on steroids: in vivo and in vitro investigations of 14α-hydroxylase activity.

    PubMed

    Kolet, Swati P; Haldar, Saikat; Niloferjahan, Siddiqui; Thulasiram, Hirekodathakallu V

    2014-07-01

    Transformation of testosterone and progesterone into synthetically challenging 14α-hydroxy derivatives was achieved by using fungal strain Mucor hiemalis. Prolonged incubation led to the formation of corresponding 6β/7α,14α-dihydroxy metabolites. The position and stereochemistry of newly introduced hydroxyl group was determined by detailed spectroscopic analyses. The time course experiment indicated that fungal strain initiated transformation by hydroxylation at 14α-position followed by at 6β- or 7α-positions. Studies using cell-free extracts suggest that the 14α-hydroxylase activity is NADPH dependent and belongs to the cytochrome P450 family.

  19. Elucidation of hydroxyl groups-antioxidant relationship in mono- and dihydroxyflavones based on O-H bond dissociation enthalpies.

    PubMed

    Treesuwan, Witcha; Suramitr, Songwut; Hannongbua, Supa

    2015-06-01

    Radical scavenging potential is the key to anti-oxidation of hydroxyflavones which generally found in fruits and vegetables. The objective of this work was to investigate the influence of hydroxyl group on the O-H bond dissociation enthalpies (BDE) from a series of mono- and dihydroxyflavones. Calculation at the B3LYP/6-31G(d,p) level reveals the important roles of an additional one hydroxyl group to boost the BDE of hydroxyflavones that were a stabilization of the generated radicals through attractive H-bond interactions, an ortho- and para-dihydroxyl effect, and a presence of the 3-OH in dihydroxyflavones. On the other hand, the meta-dihydroxyl effect and range-hydroxyl effect especially associated with the either 5-OH or 8-OH promoted greater BDE. Results did not only confirm that dihydroxyflavones had lower BDE than monohydroxyflavones but also suggest the selective potent hydroxyflavone molecules that are the 6'-hydroxyflavone (for monohydroxyflavone) and the 5',6'-, 7,8- and 3',4'-dihydroxyflavone which the corresponding radical preferable generated at C6'-O•, C8-O• and C4'-O•, respectively. Electron distribution was limited only over the two connected rings of hydroxyflavones while the expansion distribution into C-ring could be enhanced if the radical was formed especially for the 2',3'- and 5',6'dihydroxyflavone radicals. The delocalized bonds were strengthened after radical was generated. However the 5-O• in 5,6-dihydroxyflavone and the 3-O• in 3,6'-dihydroxyflavone increased the bond order at C4-O11 which might interrupt the conjugated delocalized bonds at the keto group.

  20. Hydroxylated analogs of mexiletine as tools for structural-requirements investigation of the sodium channel blocking activity.

    PubMed

    Catalano, Alessia; Carocci, Alessia; Cavalluzzi, Maria M; Di Mola, Antonia; Lentini, Giovanni; Lovece, Angelo; Dipalma, Antonella; Costanza, Teresa; Desaphy, Jean-François; Conte Camerino, Diana; Franchini, Carlo

    2010-06-01

    [2-(2-Aminopropoxy)-1,3-phenylene]dimethanol 1 and 4-(2-aminopropoxy)-3-(hydroxymethyl)-5-methylphenol 2, two dihydroxylated analogs of mexiletine - a well known class IB anti-arrhythmic drug - were synthesized and used as pharmacological tools to investigate the blocking-activity requirements of human skeletal muscle, voltage-gated sodium channel. The very low blocking activity shown by newly synthesized compounds corroborates the hypothesis that the presence of a phenolic group in the para-position to the aromatic moiety and/or benzylic hydroxyl groups on the aromatic moiety of local anesthetic-like drugs impairs either the transport to or the interaction with the binding site in the pore of Na(+) channels. PMID:20509146

  1. PGMA-Based Star-Like Polycations with Plentiful Hydroxyl Groups Act as Highly Efficient miRNA Delivery Nanovectors for Effective Applications in Heart Diseases.

    PubMed

    Li, Rui-Quan; Wu, Yina; Zhi, Ying; Yang, Xinchao; Li, Yulin; Xua, Fu-Jian; Du, Jie

    2016-09-01

    Poly(glycidyl methacrylate)-based star-like polycations with rich hydrophilic hydroxyl groups can efficiently transfer miRNA into primary cardiac fibroblasts for effective applications in cardiac diseases, such as inhibition of cardiac fibrosis and hypertrophy.

  2. Studies on the mechanism of activation of microsomal benzo(a)pyrene hydroxylation by flavonoids

    SciTech Connect

    Huang, M.T.; Chang, R.L.; Fortner, J.G.; Conney, A.H.

    1981-07-10

    7,8-benzoflavone or flavone stimulates the hydroxylation of benzo(a)pyrene by liver microsomes from rabbit, hamster, and man severalfold. Little or no activation by the flavonoid occurs in liver microsomes from rat or guinea pig. Intact liver microsomal membranes are not required for the activation. Although 7,8-benzoflavone does not stimulate the NADPH-dependent reduction of cytochrome c by rabbit liver microsomes, the NADPH-dependent reduction of cytochrome P-450 is stimulated by 7,8-benzoflavone either in the presence or absence of benzo(a)pyrene. Purified cytochrome P-450 reductase causes an increase in the rate of benzo(a)pyrene hydroxylation in cholate-solubilized liver microsomes from all of the species studied. In cholate-solubilized microsomes from all of the species susceptible for flavonoid activation, 7,8-benzoflavone decreases the K/sub m/ for cytochrome P-450 reductase and increases the V/sub max/ for benzo(a)pyrene hydroxylation. With cholate-solubilized human liver microsomes, the K/sub m/ for cytochrome P-450 reductase in the absence of flavonoids was about 3-fold higher than in the presence of 100 ..mu..M 7,8-benzoflavone or 500 ..mu..M flavone. 7,8-benzoflavone and flavone stimulate the hydroxylation of benzo(a)pyrene in liver microsomes at least in part by enhancing the interaction between cytochrome P-450 and cytochrome P-450 reductase. 7,8-benzoflavone does not influence the K/sub m/ for benzo(a)pyrene or NADPH, but the V/sub max/ values for benzo(a)pyrene are increased from 2.5- to 4-fold in rabbit liver microsomes. 7,8-benzoflavone does not stimulate the cumene hydroperoxide-dependent hydroxylation of benzo(a)pyrene by rabbit liver microsomes. In two partially purified cytochrome P-450 fractions from rabbit liver microsomes, flavone has a specific stimulatory effect on one of the reconstituted partially purified cytochrome P-450 systems, but an inhibitory effect on the other.

  3. Synthesis and characterization of unsymmetrical disubstituted ferrocenes possessing hydroxyl group as a new donor/acceptor of hydrogen bond

    NASA Astrophysics Data System (ADS)

    Lapić, Jasmina; Pezerović, Alma; Cetina, Mario; Djaković, Senka; Rapić, Vladimir

    2011-03-01

    The preparation and characterization of heteroannularly disubstituted ferrocene derivatives 2- 8 are described, with a special attention given on the conformation and hydrogen-bonding of compounds 3b, 7a and 8a. Compounds 3 and 8 comprise hydroxyl group as a new hydrogen bond donor/acceptor and are precursors for preparation of organometallics in asymmetric bioconjugates with natural amino acids. Newly prepared compounds are characterized by elemental analysis, FTIR and NMR spectroscopy. The structures of compounds 1, 3b and 6a were also confirmed by X-ray crystal structure analysis.

  4. New lipophilic piceatannol derivatives exhibiting antioxidant activity prepared by aromatic hydroxylation with 2-iodoxybenzoic acid (IBX).

    PubMed

    Bernini, Roberta; Barontini, Maurizio; Spatafora, Carmela

    2009-01-01

    Piceatannol (E-3,5,3',4'-tetrahydroxystilbene) is a phytoalexin synthesized in grapes in response to stress conditions. It exhibits strong antioxidant and antileukaemic activities due to the presence of the catechol moiety. To modify some physical properties like solubility, and miscibility in non-aqueous media some new previously unreported piceatannol derivatives having lipophilic chains on the A-ring were prepared in good yields by a simple and efficient procedure. The key step was a chemo- and regioselective aromatic hydroxylation with 2-iodoxybenzoic acid (IBX). The new compounds showed antioxidant activity and seemed promising for possible applications as multifunctional emulsifiers in food, cosmetic and pharmaceutical fields.

  5. Hemiacetal stabilization in a chymotrypsin inhibitor complex and the reactivity of the hydroxyl group of the catalytic serine residue of chymotrypsin.

    PubMed

    Cleary, Jennifer A; Doherty, William; Evans, Paul; Malthouse, J Paul G

    2014-06-01

    The aldehyde inhibitor Z-Ala-Ala-Phe-CHO has been synthesized and shown by (13)C-NMR to react with the active site serine hydroxyl group of alpha-chymotrypsin to form two diastereomeric hemiacetals. For both hemiacetals oxyanion formation occurs with a pKa value of ~7 showing that chymotrypsin reduces the oxyanion pKa values by ~5.6 pKa units and stabilizes the oxyanions of both diastereoisomers by ~32kJmol(-1). As pH has only a small effect on binding we conclude that oxyanion formation does not have a significant effect on binding the aldehyde inhibitor. By comparing the binding of Z-Ala-Ala-Phe-CHO with that of Z-Ala-Ala-Phe-H we estimate that the aldehyde group increases binding ~100 fold. At pH7.2 the effective molarity of the active site serine hydroxy group is ~6000 which is ~7× less effective than with the corresponding glyoxal inhibitor. Using (1)H-NMR we have shown that at both 4 and 25°C the histidine pKa is ~7.3 in free chymotrypsin and it is raised to ~8 when Z-Ala-Ala-Phe-CHO is bound. We conclude that oxyanion formation only has a minor role in raising the histidine pKa and that the aldehyde hydrogen must be replaced by a larger group to raise the histidine pKa>10 and give stereospecific formation of tetrahedral intermediates. The results show that a large increase in the pKa of the active site histidine is not needed for the active site serine hydroxyl group to have an effective molarity of 6000.

  6. Synthesis, characterization and phytotoxic activity of hydroxylated isobenzofuran-1(3H)-ones

    NASA Astrophysics Data System (ADS)

    Teixeira, R. R.; Pereira, J. L.; Da Silva, S. F.; Guilardi, S.; Paixão, D. A.; Anconi, C. P. A.; De Almeida, W. B.; Ellena, J.; Forlani, G.

    2014-03-01

    Two hydroxylated isobenzofuranones 3 and 4 were synthesized from benzoic acids. The compounds were fully characterized by IR, NMR (1H and 13C), HRMS, and X-ray crystallography. Compounds 3 and 4 crystallized in the space group Pc and P21/n, respectively. DFT calculations were used to confirm undoubtedly their NMR chemical shifts. Biological assays showed that these compounds are capable of interfering with the radicle growth of monocotyledonous and dicotyledonous species, whereas the photosynthetic electron transport chain was substantially unaffected.

  7. Mechanistic Insights of Ethanol Steam Reforming over Ni–CeO x (111): The Importance of Hydroxyl Groups for Suppressing Coke Formation

    DOE PAGES

    Liu, Zongyuan; Duchoň, Tomáš; Wang, Huanru; Peterson, Erik W.; Zhou, Yinghui; Luo, Si; Zhou, Jing; Matolín, Vladimir; Stacchiola, Dario J.; Rodriguez, José A.; et al

    2015-07-30

    We have studied the reaction of ethanol and water over Ni–CeO2-x(111) model surfaces to elucidate the mechanistic steps associated with the ethanol steam reforming (ESR) reaction. Our results provide insights about the importance of hydroxyl groups to the ESR reaction over Ni-based catalysts. Systematically, we have investigated the reaction of ethanol on Ni–CeO2-x(111) at varying Ce³⁺ concentrations (CeO1.8–2.0) with absence/presence of water using a combination of soft X-ray photoelectron spectroscopy (sXPS) and temperature-programmed desorption (TPD). Consistent with previous reports, upon annealing, metallic Ni formed on reduced ceria while NiO was the main component on fully oxidized ceria. Ni⁰ is themore » active phase leading to both the C–C and C–H cleavage of ethanol but is also responsible for carbon accumulation or coking. We have identified a Ni₃C phase that formed prior to the formation of coke. At temperatures above 600K, the lattice oxygen from ceria and the hydroxyl groups from water interact cooperatively in the removal of coke, likely through a strong metal–support interaction between nickel and ceria that facilitates oxygen transfer.« less

  8. Mechanistic Insights of Ethanol Steam Reforming over Ni–CeO x (111): The Importance of Hydroxyl Groups for Suppressing Coke Formation

    SciTech Connect

    Liu, Zongyuan; Duchoň, Tomáš; Wang, Huanru; Peterson, Erik W.; Zhou, Yinghui; Luo, Si; Zhou, Jing; Matolín, Vladimir; Stacchiola, Dario J.; Rodriguez, José A.; Senanayake, Sanjaya D.

    2015-07-30

    We have studied the reaction of ethanol and water over Ni–CeO2-x(111) model surfaces to elucidate the mechanistic steps associated with the ethanol steam reforming (ESR) reaction. Our results provide insights about the importance of hydroxyl groups to the ESR reaction over Ni-based catalysts. Systematically, we have investigated the reaction of ethanol on Ni–CeO2-x(111) at varying Ce³⁺ concentrations (CeO1.8–2.0) with absence/presence of water using a combination of soft X-ray photoelectron spectroscopy (sXPS) and temperature-programmed desorption (TPD). Consistent with previous reports, upon annealing, metallic Ni formed on reduced ceria while NiO was the main component on fully oxidized ceria. Ni⁰ is the active phase leading to both the C–C and C–H cleavage of ethanol but is also responsible for carbon accumulation or coking. We have identified a Ni₃C phase that formed prior to the formation of coke. At temperatures above 600K, the lattice oxygen from ceria and the hydroxyl groups from water interact cooperatively in the removal of coke, likely through a strong metal–support interaction between nickel and ceria that facilitates oxygen transfer.

  9. A functional polyester carrying free hydroxyl groups promotes the mineralization of osteoblast and human mesenchymal stem cell extracellular matrix.

    PubMed

    Bi, Xiaoping; You, Zhengwei; Gao, Jin; Fan, Xianqun; Wang, Yadong

    2014-06-01

    Functional groups can control biointerfaces and provide a simple way to make therapeutic materials. We recently reported the design and synthesis of poly(sebacoyl diglyceride) (PSeD) carrying a free hydroxyl group in its repeating unit. This paper examines the use of this polymer to promote biomineralization for application in bone tissue engineering. PSeD promoted more mineralization of extracellular matrix secreted by human mesenchymal stem cells and rat osteoblasts than poly(lactic-co-glycolic acid) (PLGA), which is currently widely used in bone tissue engineering. PSeD showed in vitro osteocompatibility and in vivo biocompatibility that matched or surpassed that of PLGA, as well as supported the attachment, proliferation and differentiation of rat osteoblasts and human mesenchymal stem cells. This demonstrates the potential of PSeD for use in bone regeneration. PMID:24560799

  10. Investigation of water and hydroxyl groups associated with coal fly ash by thermal desorption and fourier transform infrared photoacoustic spectroscopies

    SciTech Connect

    Seaverson, L.M.; McClelland, J.F.; Burnet, G.; Anderegg, J.W.; Iles, M.K.

    1985-01-01

    Thermal desorption spectrometry (TDS) and Fourier transform infrared photoacoustic spectroscopy (FT-IR/PAS) have been used in combination to analyze the water and hydroxyl groups associated with four coal fly ashes. Measurements using the former technique on these ashes resulted in identification of three water desorption regions in the temperature range from 25/sup 0/ to 1100/sup 0/C. The regions consisted of a small desorption peak at 50/sup 0/, a broad band from 180/sup 0/ to 400/sup 0/, and an intense peak from 400/sup 0/ to 590/sup 0/. No additional water desorption was observed up to 1100/sup 0/. A fourth ash gave a similar spectrum except that it lacked the intense last peak. The TDS spectra together with FT-IR/PAS spectra taken on samples exposed to pre- and post-desorption peak temperatures allowed the first TDS peak to be assigned to the desorption of physically adsorbed water, the broad band to desorption of hydrogenbonded surface hydroxyls, and the intense last peak to the decomposition of Ca(OH)/sub 2/.

  11. Production of Hydroxyl Radical via the Activation of Hydrogen Peroxide by Hydroxylamine.

    PubMed

    Chen, Liwei; Li, Xuchun; Zhang, Jing; Fang, Jingyun; Huang, Yanmin; Wang, Ping; Ma, Jun

    2015-09-01

    The production of the hydroxyl radical (HO·) is important in environmental chemistry. This study reports a new source of HO· generated solely from hydrogen peroxide (H2O2) activated by hydroxylamine (HA). Electron paramagnetic resonance analysis and the oxidation of a HO· probe, benzoic acid, were used to confirm the production of HO·. The production of HO· increased with increasing concentrations of either HA or H2O2 as well as decreasing pH. The second-order rate constant for the reaction was (2.2 ± 0.2) × 10(-4) M(-1) s(-1). HO· was probably produced in two steps: the activation of H2O2 by protonated HA and then reaction between the H2O2 and the intermediate protonated aminoxyl radical generated in the first step. Such a two-step oxidation can possibly be ascribed to the ionizable hydroxyl moiety in the molecular structure of HA, as is suggested by comparing the reactivity of a series of HA derivatives in HO· production. The results shed light on a previously unknown source of HO· formation, which broadens the understanding of its role in environmental processes.

  12. Band profile of hydroxyl groups in the infrared spectrum of hydrogen-bonded surface complexes: Ammonia on silicon dioxide

    SciTech Connect

    Pavlov, A.Y.; Tsyganenko, A.A.

    1994-07-01

    Dependences of the band maximum and band half-width of the stretching modes of surface OH and OD groups perturbed by ammonia adsorption on Aerosil were studied as functions of sample temperature, amount of adsorbed ammonia, and thermal treatment in vacuum. The appearance of a low-frequency wing was explained by the formation of polymer chains of OH groups coupled via adsorbed molecules. The latter tend to form a second bond with an oxygen atom of the neighboring OH group in addition to a hydrogen bond with a hydroxyl proton via nitrogen. The wide band at 3250 cm{sup -1} was assigned to NH groups of adsorbed molecules perturbed by H-bonding with oxygen. This band is observed as a shoulder of the coupled-OH group band. The large width of the latter as well as its temperature behavior was explained by differences in the arrangement of OH groups and by anharmonic coupling with the low-frequency vibrational modes of the complex. 14 refs., 4 figs., 4 tabs.

  13. Development of colorimetric HTS assay of cytochrome p450 for ortho-specific hydroxylation, and engineering of CYP102D1 with enhanced catalytic activity and regioselectivity.

    PubMed

    Choi, Kwon-Young; Jung, Eun-Ok; Yun, Hyungdon; Yang, Yung-Hun; Kazlauskas, Romas J; Kim, Byung-Gee

    2013-07-01

    A current challenge in high-throughput screening (HTS) of hydroxylation reactions by P450 is a fast and sensitive assay for regioselective hydroxylation against millions of mutants. We have developed a solid-agar plate-based HTS assay for screening ortho-specific hydroxylation of daidzein by sensing formaldehyde generated from the O-dealkylation reaction. This method adopts a colorimetric dye, pararosaniline, which has previously been used as an aldehyde-specific probe within cells. The rationale for this method lies in the fact that the hydroxylation activity at ortho-carbon position to COH correlates with a linear relationship to O-dealkylation activity on chemically introduced methoxy group at the corresponding COH. As a model system, a 4',7-dihydroxyisoflavone (daidzein) hydroxylase (CYP102D1 F96V/M246I), which catalyzes hydroxylation at ortho positions of the daidzein A/B-ring, was examined for O-dealklyation activity, by using permethylated daidzein as a surrogate substrate. By using the developed indirect bishydroxylation screening assay, the correlation coefficient between O-dealkylation and bishydroxylation activity for the template enzyme was 0.72. For further application of this assay, saturation mutants at A273/G274/T277 were examined by mutant screening with a permethylated daidzein analogue substrate (A-ring inactivated in order to find enhanced 3'-regioselectiviy). The whole-cell biotransformation of daidzein by final screened mutant G1 (A273H/G274E/T277G) showed fourfold increased conversion yield, with 14.3 mg L(-1) production titer and greatly increased 3'-regioselectiviy (3'/6=11.8). These results show that there is a remarkably high correlation (both in vitro and in vivo), thus suggesting that this assay would be ideal for a primary HTS assay for P450 reactions.

  14. The Antimicrobial Activity of Gramicidin A Is Associated with Hydroxyl Radical Formation

    PubMed Central

    Liou, Je-Wen; Hung, Yu-Jiun; Yang, Chin-Hao; Chen, Yi-Cheng

    2015-01-01

    Gramicidin A is an antimicrobial peptide that destroys gram-positive bacteria. The bactericidal mechanism of antimicrobial peptides has been linked to membrane permeation and metabolism disruption as well as interruption of DNA and protein functions. However, the exact bacterial killing mechanism of gramicidin A is not clearly understood. In the present study, we examined the antimicrobial activity of gramicidin A on Staphylococcus aureus using biochemical and biophysical methods, including hydroxyl radical and NAD+/NADH cycling assays, atomic force microscopy, and Fourier transform infrared spectroscopy. Gramicidin A induced membrane permeabilization and changed the composition of the membrane. The morphology of Staphylococcus aureus during gramicidin A destruction was divided into four stages: pore formation, water permeability, bacterial flattening, and lysis. Changes in membrane composition included the destruction of membrane lipids, proteins, and carbohydrates. Most interestingly, we demonstrated that gramicidin A not only caused membrane permeabilization but also induced the formation of hydroxyl radicals, which are a possible end product of the transient depletion of NADH from the tricarboxylic acid cycle. The latter may be the main cause of complete Staphylococcus aureus killing. This new finding may provide insight into the underlying bactericidal mechanism of gA. PMID:25622083

  15. Synthesis and surface activities of a novel di-hydroxyl-sulfate-betaine-type zwitterionic gemini surfactants

    NASA Astrophysics Data System (ADS)

    Geng, Xiang F.; Hu, Xing Q.; Xia, Ji J.; Jia, Xue C.

    2013-04-01

    A series of novel di-hydroxyl-sulfate-betaine-type zwitterionic gemini surfactants of 1,2-bis[N-ethyl-N-(2-hydroxyl-3-sulfopropyl)-alkylammonium] alkyl betaines (DBAs-n, where s and n represent the spacer length of 2, 4 and 6 and the hydrocarbon chain length of 8, 12, 14, 16 and 18, respectively) were synthesized by reacting alkylamine with sodium 3-chloro-2-hydroxypropanesulfonate (the alternative sulphonated agent), followed by the reactions with а,ω-dibromoalkyl and then ethyl bromide. Their adsorption and aggregation properties were investigated by means of equilibrium surface tension, dynamic light-scattering (DLS) and transmission electron microscopy (TEM). DBAs-n gemini surfactants showed excellent surface activities and packed tightly at the interface. For example, the minimum CMC value for DBAs-n series was of the order of 10-5 M and the surface tension of water can be decreased as low as 22.2 mN/m. It was also found that the aggregates of DBAs-n solutions were significantly dependent on their hydrocarbon chain lengths. The aggregates changed from vesicles to entangled fiber-like micelles as the chain length increased from dodecyl to tetradecyl.

  16. The antimicrobial activity of gramicidin A is associated with hydroxyl radical formation.

    PubMed

    Liou, Je-Wen; Hung, Yu-Jiun; Yang, Chin-Hao; Chen, Yi-Cheng

    2015-01-01

    Gramicidin A is an antimicrobial peptide that destroys gram-positive bacteria. The bactericidal mechanism of antimicrobial peptides has been linked to membrane permeation and metabolism disruption as well as interruption of DNA and protein functions. However, the exact bacterial killing mechanism of gramicidin A is not clearly understood. In the present study, we examined the antimicrobial activity of gramicidin A on Staphylococcus aureus using biochemical and biophysical methods, including hydroxyl radical and NAD+/NADH cycling assays, atomic force microscopy, and Fourier transform infrared spectroscopy. Gramicidin A induced membrane permeabilization and changed the composition of the membrane. The morphology of Staphylococcus aureus during gramicidin A destruction was divided into four stages: pore formation, water permeability, bacterial flattening, and lysis. Changes in membrane composition included the destruction of membrane lipids, proteins, and carbohydrates. Most interestingly, we demonstrated that gramicidin A not only caused membrane permeabilization but also induced the formation of hydroxyl radicals, which are a possible end product of the transient depletion of NADH from the tricarboxylic acid cycle. The latter may be the main cause of complete Staphylococcus aureus killing. This new finding may provide insight into the underlying bactericidal mechanism of gA.

  17. Influence of Hydroxyl Group Position and Temperature on Thermophysical Properties of Tetraalkylammonium Hydroxide Ionic Liquids with Alcohols

    PubMed Central

    Attri, Pankaj; Baik, Ku Youn.; Venkatesu, Pannuru; Kim, In Tae; Choi, Eun Ha

    2014-01-01

    In this work, we have explored the thermophysical properties of tetraalkylammonium hydroxide ionic liquids (ILs) such as tetrapropylammonium hydroxide (TPAH) and tetrabutylammonium hydroxide (TBAH) with isomers of butanol (1-butanol, 2-butanol and 2-methyl-2-propanol) within the temperature range 293.15–313.15 K, with interval of 5 K and over the varied concentration range of ILs. The molecular interactions between ILs and butanol isomers are essential for understanding the function of ILs in related measures and excess functions are sensitive probe for the molecular interactions. Therefore, we calculated the excess molar volume (VE) and the deviation in isentropic compressibility (Δκs) using the experimental values such as densities (ρ) and ultrasonic sound velocities (u) that are measured over the whole compositions range at five different temperatures (293.15, 298.15, 303.15, 308.15 and 313.15 K) and atmospheric pressure. These excess functions were adequately correlated by using the Redlich–Kister polynomial equation. It was observed that for all studied systems, the VE and Δκs values are negative for the whole composition range at 293.15 K. And, the excess function follows the sequence: 2-butanol>1-butanol>2-methyl-2-propanol, which reveals that (primary or secondary or tertiary) position of hydroxyl group influence the magnitude of interactions with ILs. The negative values of excess functions are contributions from the ion-dipole interaction, hydrogen bonding and packing efficiency between the ILs and butanol isomers. Hence, the position of hydroxyl group plays an important role in the interactions with ILs. The hydrogen bonding features between ILs and alcohols were analysed using molecular modelling program by using HyperChem 7. PMID:24489741

  18. Influence of hydroxyl group position and temperature on thermophysical properties of tetraalkylammonium hydroxide ionic liquids with alcohols.

    PubMed

    Attri, Pankaj; Baik, Ku Youn; Venkatesu, Pannuru; Kim, In Tae; Choi, Eun Ha

    2014-01-01

    In this work, we have explored the thermophysical properties of tetraalkylammonium hydroxide ionic liquids (ILs) such as tetrapropylammonium hydroxide (TPAH) and tetrabutylammonium hydroxide (TBAH) with isomers of butanol (1-butanol, 2-butanol and 2-methyl-2-propanol) within the temperature range 293.15-313.15 K, with interval of 5 K and over the varied concentration range of ILs. The molecular interactions between ILs and butanol isomers are essential for understanding the function of ILs in related measures and excess functions are sensitive probe for the molecular interactions. Therefore, we calculated the excess molar volume (V(E) ) and the deviation in isentropic compressibility (Δκs ) using the experimental values such as densities (ρ) and ultrasonic sound velocities (u) that are measured over the whole compositions range at five different temperatures (293.15, 298.15, 303.15, 308.15 and 313.15 K) and atmospheric pressure. These excess functions were adequately correlated by using the Redlich-Kister polynomial equation. It was observed that for all studied systems, the V(E) and Δκs values are negative for the whole composition range at 293.15 K. And, the excess function follows the sequence: 2-butanol>1-butanol>2-methyl-2-propanol, which reveals that (primary or secondary or tertiary) position of hydroxyl group influence the magnitude of interactions with ILs. The negative values of excess functions are contributions from the ion-dipole interaction, hydrogen bonding and packing efficiency between the ILs and butanol isomers. Hence, the position of hydroxyl group plays an important role in the interactions with ILs. The hydrogen bonding features between ILs and alcohols were analysed using molecular modelling program by using HyperChem 7.

  19. Protonated Dipeptide Losses from b 5 and b 4 Ions of Side Chain Hydroxyl Group Containing Pentapeptides

    NASA Astrophysics Data System (ADS)

    Atik, A. Emin; Yalcin, Talat

    2013-10-01

    In this study, C-terminal protonated dipeptide eliminations were reported for both b 5 and b 4 ions of side chain hydroxyl group (-OH) containing pentapeptides. The study utilized the model C-terminal amidated pentapeptides having sequences of XGGFL and AXVYI, where X represents serine (S), threonine (T), glutamic acid (E), aspartic acid (D), or tyrosine (Y) residue. Upon low-energy collision-induced dissociation (CID) of XGGFL (where X = S, T, E, D, and Y) model peptide series, the ions at m/z 279 and 223 were observed as common fragments in all b 5 and b 4 ion (except b 4 ion of YGGFL) mass spectra, respectively. By contrast, peptides, namely SMeGGFL-NH2 and EOMeGGFL-NH2, did not show either the ion at m/z 279 or the ion at m/z 223. It is shown that the side chain hydroxyl group is required for the possible mechanism to take place that furnishes the protonated dipeptide loss from b 5 and b 4 ions. In addition, the ions at m/z 295 and 281 were detected as common fragments in all b 5 and b 4 ion (except b 4 ion of AYVYI) mass spectra, respectively, for AXVYI model peptide series. The MS4 experiments exhibited that the fragment ions at m/z 279, 223, 295, and 281 entirely reflect the same fragmentation behavior of [M + H]+ ion generated from commercial dipeptides FL-OH, GF-OH, YI-OH, and VY-OH. These novel eliminations reported here for b 5 and b 4 ions can be useful in assigning the correct and reliable peptide sequences for high-throughput proteomic studies.

  20. Detection of hydroxyl radicals during regeneration of granular activated carbon in dielectric barrier discharge plasma system

    NASA Astrophysics Data System (ADS)

    Tang, Shoufeng; Lu, Na; Shang, Kefeng; Li, Jie; Wu, Yan

    2013-03-01

    To understand the reactions taking place in the dielectric barrier discharge (DBD) plasma system of activated carbon regeneration, the determination of active species is necessary. A method based on High Performance Liquid Chromatography with radical trapping by salicylic acid, has been developed to measure hydroxyl radical (•OH) in the DBD plasma reactor. The effects of applied voltage, treatment time, and gas flow rate and atmosphere were investigated. Experimental results indicated that increasing voltage, treatment time and air flow rate could enhance the formation of •OH. Oxygen atmosphere and a suitable GAC water content were contributed to •OH generation. The results give an insight into plasma chemical processes, and can be helpful to optimize the design and application for the plasma system.

  1. Synthesis, photocatalytic activity, and photogenerated hydroxyl radicals of monodisperse colloidal ZnO nanospheres

    NASA Astrophysics Data System (ADS)

    Yang, Chong; Li, Qingsong; Tang, Limei; Xin, Kun; Bai, Ailing; Yu, Yingmin

    2015-12-01

    In the present study, monodisperse colloidal zinc oxide (ZnO) nanospheres were successfully synthesized via a newly developed two-stage solution method followed by facile calcination at various temperatures. The effects of calcination temperature on the structure, morphology, and optical properties as well as the photocatalytic activity of the as-made ZnO samples were investigated systematically by Fourier transform infrared spectrometry, X-ray diffraction, field emission scanning electron microscopy, nitrogen adsorption/desorption isotherms, diffuse reflectance UV-visible spectroscopy (DRS), photoluminescence, and related photocatalytic activity tests. The thermal decomposition was analyzed by thermogravimetric analysis. The crystallinity was found to gradually increase with increasing calcination temperature, whereas the decrease in the Brunauer-Emmett-Teller specific surface area of the samples with calcination may be ascribed to the increased particle size. The DRS results provided clear evidence for the decrease in band gap energy of ZnO samples with an increase in calcination temperature. The photoluminescence spectra demonstrated the calcination-dependent emission features, especially the UV emission intensity. In particular, the ZnO product calcined at 400 °C exhibited the highest photocatalytic activity, degrading methylene blue by almost 99.1% in 70 min, which is ascribed to the large specific surface area and pore volume, high electron-hole pair separation efficient, and great redox potential of the obtained ZnO nanoparticles. In addition, the production of photogenerated hydroxyl radicals (•OH) was consistent with the methylene blue degradation efficiency over the as-made ZnO nanoparticles. Using isopropanol as a hydroxyl radical scavenger, •OH was determined to be the main active oxygen species in the photocatalytic process. A possible mechanism of photodegradation under UV light irradiation also is proposed.

  2. Heterogeneity of hydroxyl and deuteroxyl groups on the surface of TiO{sub 2} polymorphs

    SciTech Connect

    Contescu, C.; Popa, V.T.; Schwarz, J.A.

    1996-06-01

    Potentiometric titration data from pure rutile, anatase, and a commercial fumed titania (Degussa P25) were analyzed in terms of proton binding isotherms from which proton affinity distributions (PADs) of surface sites were obtained. As-received samples, whose thermal and storage history were not systematically controlled, as well as samples subjected to controlled calcination-rehydration-drying treatments were studied. The results indicated the occurrence of a limited number of surface groups on the two polymorphs. The behavior of pure rutile and anatase could be admixed to simulate the acid-base behavior of the commercial sample; on this basis the surface of fumed titania consists largely of anatase-like structures with a small contribution (7%) of rutile-like groups. The region of {nu}{sub OD} stretching vibrations of isolated -OD groups on extensively dehydroxylated samples was found to correlate with the pK`s determined from PADs. A qualitative assignment of measured pK values based on either the original MUSIC model (Hiemstra, T., de Wit, J.C.M., and Van Riemsdijk, W.H., J. Colloid Interface Sci. 133, 105 (1989)) or a refined version of it is presented.

  3. The effect of surfactant-free TiO2 surface hydroxyl groups on physicochemical, optical and self-cleaning properties of developed coatings on polycarbonate

    NASA Astrophysics Data System (ADS)

    Yaghoubi, H.; Dayerizadeh, A.; Han, S.; Mulaj, M.; Gao, W.; Li, X.; Muschol, M.; Ma, S.; Takshi, A.

    2013-12-01

    TiO2 is a prototypical transition metal oxide with physicochemical properties that can be modified more readily through sol-gel synthesis than through other techniques. Herein, we report on the change in the density of the hydroxyl groups on the surface of synthesized surfactant-free TiO2 nanoparticles in water due to varying the pH (7.3, 8.3, 9.3 and 10.3) of the peroxotitanium complex, i.e. the amorphous sol, prior to refluxing. This resulted in colloidal solutions with differing crystallinity, nanoparticle size, optical indirect bandgaps and photocatalytic activity. It was shown that increasing the density of hydroxyl groups on TiO2 particles coupled with low-temperature annealing (90 °C) induced an anatase to rutile transformation. Increasing the pH of the peroxotitanium complex interrupted the formation of anatase phase in crystalline sol, as evidenced by intensity increases of the Raman bands at ˜822 (Ti-O-H) and 906 cm-1 (vibrational Ti-O-H) and an intensity decrease of the band at 150 cm-1 (anatase photonic Eg). Films prepared from higher pH suspensions showed lower roughness. The reaction rate constants for photo-induced self-cleaning activity of TiO2 films prepared from colloidal solutions at pH 7.3, 8.3, 9.3 and 10.3 were estimated at 0.017 s-1, 0.014 s-1, 0.007 s-1 and 0.006 s-1, respectively.

  4. The role of hydroxyl radical as a messenger in Cr(VI)-induced p53 activation.

    PubMed

    Wang, S; Leonard, S S; Ye, J; Ding, M; Shi, X

    2000-09-01

    The present study investigates whether reactive oxygen species (ROS) are involved in p53 activation, and if they are, which species is responsible for the activation. Our hypothesis is that hydroxyl radical (.OH) functions as a messenger for the activation of this tumor suppressor protein. Human lung epithelial cells (A549) were used to test this hypothesis. Cr(VI) was employed as the source of ROS due to its ability to generate a whole spectrum of ROS inside the cell. Cr(VI) is able to activate p53 by increasing the protein levels and enhancing both the DNA binding activity and transactivation ability of the protein. Increased cellular levels of superoxide radicals (O(2)(-).), hydrogen peroxide (H(2)O(2)), and.OH radicals were detected on the addition of Cr(VI) to the cells. Superoxide dismutase, by enhancing the production of H(2)O(2) from O(2)(-). radicals, increased p53 activity. Catalase, an H(2)O(2) scavenger, eliminated.OH radical generation and inhibited p53 activation. Sodium formate and aspirin,.OH radical scavengers, also suppressed p53 activation. Deferoxamine, a metal chelator, inhibited p53 activation by chelating Cr(V) to make it incapable of generating radicals from H(2)O(2). NADPH, which accelerated the one-electron reduction of Cr(VI) to Cr(V) and increased.OH radical generation, dramatically enhanced p53 activation. Thus.OH radical generated from Cr(VI) reduction in A549 cells is responsible for Cr(VI)-induced p53 activation.

  5. Short-step chemical synthesis of DNA by use of MMTrS group for protection of 5'-hydroxyl group.

    PubMed

    Shiraishi, Miyuki; Utagawa, Eri; Ohkubo, Akihiro; Sekine, Mitsuo; Seio, Kohji

    2007-01-01

    4-methoxytrithylthio (MMTrS) group was applied for the appropriately protected four canonical nucleosides. We prepared the phosphoroamidite units by use of these nucleosides and developed the synthesis of oligodeoxynucleotides without any acidic treatment. Moreover, the new DNA synthesis protocol was applied to an automated DNA synthesizer for the synthesis of longer oligodeoxynucleotides. PMID:18029620

  6. Correlation of the antimicrobial activity of salicylaldehydes with broadening of the NMR signal of the hydroxyl proton. Possible involvement of proton exchange processes in the antimicrobial activity.

    PubMed

    Elo, Hannu; Kuure, Matti; Pelttari, Eila

    2015-03-01

    Certain substituted salicylaldehydes are potent antibacterial and antifungal agents and some of them merit consideration as potential chemotherapeutic agents against Candida infections, but their mechanism of action has remained obscure. We report here a distinct correlation between broadening of the NMR signal of the hydroxyl proton of salicylaldehydes and their activity against several types of bacteria and fungi. When proton NMR spectra of the compounds were determined using hexadeuterodimethylsulfoxide as solvent and the height of the OH proton signal was measured, using the signal of the aldehyde proton as an internal standard, it was discovered that a prerequisite of potent antimicrobial activity is that the proton signal is either unobservable or relatively very low, i.e. that it is extremely broadened. Thus, none of the congeners whose OH proton signal was high were potent antimicrobial agents. Some congeners that gave a very low OH signal were, however, essentially inactive against the microbes, indicating that although drastic broadening of the OH signal appears to be a prerequisite, also other (so far unknown) factors are needed for high antimicrobial activity. Because broadening of the hydroxyl proton signal is related to the speed of the proton exchange process(es) involving that proton, proton exchange may be involved in the mechanism of action of the compounds. Further studies are needed to analyze the relative importance of different factors (such as electronic effects, strength of the internal hydrogen bond, co-planarity of the ring and the formyl group) that determine the rates of those processes. PMID:25621992

  7. Active phase of a Pd-Cu/ZSM-5 catalyst for benzene hydroxylation: In-situ XAFS studies

    NASA Astrophysics Data System (ADS)

    Cho, Kye-Sung; Lee, Yong-Kul

    2012-07-01

    The gas-phase hydroxylation of benzene by using a mixture of oxygen and hydrogen has been carried out over Cu/ZSM-5 catalysts modified with palladium. In-situ X-ray absorption studies employed in the course of H2-tempereature programmed reduction (H2-TPR) followed by benzene hydroxylation confirmed that the oxidic phase of Cu2+ was transformed to Cu+ during the reaction. The addition of Pd to Cu/ZSM-5 noticeably improved the reducibility of the oxidic Cu phase, which resulted in an increase in the activity of the reaction.

  8. A correlation of the rate of N-hydroxylation of aminoazo dyes with their carcinogenic activity in the rat.

    PubMed

    Kimura, T; Kodama, M; Nagata, C

    1982-01-01

    The rate of formation of N-hydroxy-N-methyl-4-aminoazobenzene (N-OH-MAB) derivatives from N,N-dimethyl-4-aminoazobenzene (DAB) derivatives and from N-methyl-4-aminoazobenzene (MAB) derivatives was measured by the e.s.r. spectroscopy, and the rate of N-demethylation of DAB derivatives was measured by h.p.l.c. The rate of formation of N-OH-MAB derivatives from DAB derivatives showed a strong correlation with their carcinogenic activity. This reaction occurs in two-steps, i.e. N-demethylation followed by N-hydroxylation. The rate of N-demethylation of DAB derivatives was not correlated with their carcinogenic activity. On the other hand, the rate of N-hydroxylation of MAB derivatives was well correlated with the carcinogenic activity of corresponding DAB derivatives. These results suggest that the carcinogenic activity of DAB derivatives in the rat was dependent upon the enzyme concerned with N-hydroxylation. The positive carcinogenicity is limited to those derivatives with a rate of N-hydroxylation above the threshold value.

  9. Possible mechanism of structural incorporation of Al into diatomite during the deposition process I. Via a condensation reaction of hydroxyl groups.

    PubMed

    Liu, Dong; Yu, Wenbin; Deng, Liangliang; Yuan, Weiwei; Ma, Lingya; Yuan, Peng; Du, Peixin; He, Hongping

    2016-01-01

    The structural incorporation of aluminium (Al) into diatomite is investigated by preparing several Al-diatomite composites by loading an Al precursor, hydroxyl aluminum polymer (Al13), onto the surface of diatomite and heating at various temperatures. The results indicate that Al was incorporated and implanted into the structure of diatomite by the condensation reaction of the hydroxyl groups of Al13 and diatomite, and the Si-O-Al(OH) groups were formed during the condensation reaction. Al incorporation by the condensation reaction of hydroxyl groups of Al13 with single silanols of diatomite occurred more readily than that with geminal silanols. The Al incorporation increased solid acidity of diatomite after Al incorporation. The acidity improvement was various for different types of acid sites, depending on the preparation temperature of the Al-incorporated diatomite. Both Brønsted and Lewis acid sites increased greatly after heating at 250 and 350 °C, but only L acid sites significantly improved after heating at 500 °C. These results demonstrate that the structural incorporation of Al(3+) ions into diatomite can occur by the condensation reaction of the hydroxyl groups of the Al precursors and diatomite. Moreover, the rich solid acid sites of Al-incorporated diatomite show its promising application as a solid acid catalyst.

  10. Plasma enhanced chemical vapour deposition of silica onto Ti: Analysis of surface chemistry, morphology and functional hydroxyl groups

    PubMed Central

    Szili, Endre J.; Kumar, Sunil; Smart, Roger St. C.; Lowe, Rachel; Saiz, Eduardo; Voelcker, Nicolas H.

    2009-01-01

    Previously, we have developed and characterised a procedure for the deposition of thin silica films by a plasma enhanced chemical vapour deposition (PECVD) procedure using tetraethoxysilane (TEOS) as the main precursor. We have used the silica coatings for improving the corrosion resistance of metals and for enhancing the bioactivity of biomedical metallic implants. Recently, we have been fine-tuning the PECVD method for producing high quality and reproducible PECVD-silica (PECVD-Si) coatings on metals, primarily for biomaterial applications. In order to understand the interaction of the PECVD-Si coatings with biological species (such as proteins and cells), it is important to first analyse the properties of the silica films deposited using the optimised parameters. Therefore, this current investigation was carried out to analyse the characteristic features of PECVD-Si deposited on Ti substrates (PECVD-Si-Ti). We determined that the PECVD-Si coatings on Ti were conformal to the substrate surface, strongly adhered to the underlying substrate and were resistant to delamination. The PECVD-Si surface was composed of stoichiometric SiO2, showed a low carbon content (below 10 at.%) and was very hydrophilic (contact angle <10°). Finally, we also showed that the PECVD-Si coatings contain functional hydroxyl groups. PMID:19809536

  11. The active site of low-temperature methane hydroxylation in iron-containing zeolites.

    PubMed

    Snyder, Benjamin E R; Vanelderen, Pieter; Bols, Max L; Hallaert, Simon D; Böttger, Lars H; Ungur, Liviu; Pierloot, Kristine; Schoonheydt, Robert A; Sels, Bert F; Solomon, Edward I

    2016-08-18

    An efficient catalytic process for converting methane into methanol could have far-reaching economic implications. Iron-containing zeolites (microporous aluminosilicate minerals) are noteworthy in this regard, having an outstanding ability to hydroxylate methane rapidly at room temperature to form methanol. Reactivity occurs at an extra-lattice active site called α-Fe(ii), which is activated by nitrous oxide to form the reactive intermediate α-O; however, despite nearly three decades of research, the nature of the active site and the factors determining its exceptional reactivity are unclear. The main difficulty is that the reactive species-α-Fe(ii) and α-O-are challenging to probe spectroscopically: data from bulk techniques such as X-ray absorption spectroscopy and magnetic susceptibility are complicated by contributions from inactive 'spectator' iron. Here we show that a site-selective spectroscopic method regularly used in bioinorganic chemistry can overcome this problem. Magnetic circular dichroism reveals α-Fe(ii) to be a mononuclear, high-spin, square planar Fe(ii) site, while the reactive intermediate, α-O, is a mononuclear, high-spin Fe(iv)=O species, whose exceptional reactivity derives from a constrained coordination geometry enforced by the zeolite lattice. These findings illustrate the value of our approach to exploring active sites in heterogeneous systems. The results also suggest that using matrix constraints to activate metal sites for function-producing what is known in the context of metalloenzymes as an 'entatic' state-might be a useful way to tune the activity of heterogeneous catalysts. PMID:27535535

  12. The active site of low-temperature methane hydroxylation in iron-containing zeolites

    NASA Astrophysics Data System (ADS)

    Snyder, Benjamin E. R.; Vanelderen, Pieter; Bols, Max L.; Hallaert, Simon D.; Böttger, Lars H.; Ungur, Liviu; Pierloot, Kristine; Schoonheydt, Robert A.; Sels, Bert F.; Solomon, Edward I.

    2016-08-01

    An efficient catalytic process for converting methane into methanol could have far-reaching economic implications. Iron-containing zeolites (microporous aluminosilicate minerals) are noteworthy in this regard, having an outstanding ability to hydroxylate methane rapidly at room temperature to form methanol. Reactivity occurs at an extra-lattice active site called α-Fe(II), which is activated by nitrous oxide to form the reactive intermediate α-O; however, despite nearly three decades of research, the nature of the active site and the factors determining its exceptional reactivity are unclear. The main difficulty is that the reactive species—α-Fe(II) and α-O—are challenging to probe spectroscopically: data from bulk techniques such as X-ray absorption spectroscopy and magnetic susceptibility are complicated by contributions from inactive ‘spectator’ iron. Here we show that a site-selective spectroscopic method regularly used in bioinorganic chemistry can overcome this problem. Magnetic circular dichroism reveals α-Fe(II) to be a mononuclear, high-spin, square planar Fe(II) site, while the reactive intermediate, α-O, is a mononuclear, high-spin Fe(IV)=O species, whose exceptional reactivity derives from a constrained coordination geometry enforced by the zeolite lattice. These findings illustrate the value of our approach to exploring active sites in heterogeneous systems. The results also suggest that using matrix constraints to activate metal sites for function—producing what is known in the context of metalloenzymes as an ‘entatic’ state—might be a useful way to tune the activity of heterogeneous catalysts.

  13. Group Activities for Math Enthusiasts

    ERIC Educational Resources Information Center

    Holdener, J.; Milnikel, R.

    2016-01-01

    In this article we present three group activities designed for math students: a balloon-twisting workshop, a group proof of the irrationality of p, and a game of Math Bingo. These activities have been particularly successful in building enthusiasm for mathematics and camaraderie among math faculty and students at Kenyon College.

  14. Novel relationship between hydroxyl radical initiation and surface group of ceramic honeycomb supported metals for the catalytic ozonation of nitrobenzene in aqueous solution.

    PubMed

    Zhao, Lei; Sun, Zhizhong; Ma, Jun

    2009-06-01

    Comparative experiments have been performed to investigate the degradation efficiency of nitrobenzene and the removal efficiency of TOC in aqueous solution bythe processes of ceramic honeycomb supported different metals (Fe, Ni, and Zn) catalytic ozonation, indicating that the modification with metals can enhance the activity of ceramic honeycomb for the catalytic ozonation of nitrobenzene, and the loading percentage of metal and the metallicity respectively presents a positive influence on the degradation of nitrobenzene. The degradation efficiency of nitrobenzene is determined by the initiation of hydroxyl radical (*OH) according to a good linear correlation in all the processes of modified ceramic honeycomb catalytic ozonation at the different loading percentages of metals. The modification of ceramic honeycomb with metals results in the conversion of the pH at the point of zero charge (pHpzc) and the evolution of surface groups. Divergence from the conventional phenomenon, the enhancement mechanism of ozone decomposition on the modified ceramic honeycomb with metals is proposed due to the basic attractive forces of electrostatic forces or/and hydrogen bonding. Consequently, a novel relationship between the initiation of *OH and the surface-OH2+ group on the modified catalyst is established based on the synergetic effect between homogeneous and heterogeneous reaction systems.

  15. Inhibition of human placental aromatase activity by hydroxylated polybrominated diphenyl ethers (OH-PBDEs)

    SciTech Connect

    Canton, Rocio F. Scholten, Deborah E.A.; Marsh, Goeran; Jong, Paul C. de; Berg, Martin van den

    2008-02-15

    Polybrominated diphenyl ethers (PBDEs) are widely used as flame retardants in many different polymers, resins and substrates. Due to their widespread production and use, their high binding affinity to particles, and their lipophilic properties, several PBDE congeners can bioaccumulate in the environment. As a result, PBDEs and their hydroxylated metabolites (OH-PBDEs) have been detected in humans and various wildlife samples, such as birds, seals, and whales. Furthermore, certain OH-PBDEs and their methoxylated derivatives (MeO-PBDEs) are natural products in the marine environment. Recently, our laboratory focused on the possible effects on steroidogenesis of PBDEs and OH-PBDEs, e.g. in the human adrenocortical carcinoma (H295R) cell line indicating that some OH-PBDEs can significantly influence steroidogenic enzymes like CYP19 (aromatase) and CYP17. In the present study, human placental microsomes have been used to study the possible interaction of twenty two OH-PBDEs and MeO-PBDEs with aromatase, the enzyme that mediates the conversion of androgens into estrogens. All OH-PBDE derivates showed significant inhibition of placental aromatase activity with IC{sub 50} values in the low micromolar range, while the MeO-PBDEs did not have any effect on this enzyme activity. Enzyme kinetics studies indicated that two OH-PBDEs, 5-hydroxy-2,2',4,4'-tetrabromodiphenyl ether (5-OH-BDE47) and 6-hydroxy-2,2',4,4'-tetrabromodiphenyl ether (6-OH-BDE47), had a mixed-type inhibition of aromatase activity with apparent K{sub i}/K{sub i}' of 7.68/0,02 {mu}M and 5.01/0.04 {mu}M respectively. For comparison, some structurally related compounds, a dihydroxylated polybrominated biphenyl, which is a natural product (2,2'-dihyroxy-3,3',5,5'-tetrabromobiphenyl (2,2'-diOH-BB80)) and its non-bromo derivative were also included in the study. Again inhibition of aromatase activity could be measured, but their potency was significantly less than those observed for the OH-PBDEs. These results show

  16. The influence of pendant hydroxyl groups on enzymatic degradation and drug delivery of amphiphilic poly[glycidol-block-(epsilon-caprolactone)] copolymers.

    PubMed

    Mao, Jing; Gan, Zhihua

    2009-11-10

    An amphiphilic diblock copolymer PG-b-PCL with well-controlled structure and pendant hydroxyl groups along hydrophilic block was synthesized by sequential anionic ring-opening polymerization. The micellization and drug release of PG-b-PCL copolymers using pyrene as a fluorescence probe were investigated for determining the influences of copolymer composition and lipase concentration on drug loading capacity and controlled release behavior. The biodegradation of PG-b-PCL copolymers was studied with microspheres as research samples. It has been concluded that the polar hydroxyl groups along each repeat unit of hydrophilic PG block in PG-b-PCL copolymer have great influences on drug encapsulation, drug release, and enzymatic degradation of micelles and microspheres.

  17. Control of oxygen atom chirality and chelate ring conformation by protected/free sugar hydroxyl groups in glucose-pendant dipicolylamine-copper(II) complexes.

    PubMed

    Mikata, Yuji; Sugai, Yuko; Yano, Shigenobu

    2004-08-01

    A pair of copper(II) complexes 1 and 2 exhibit an enantiomeric chiral center at the oxygen atom that coordinates to the metal center. The configurations of the oxygen atom chirality and the chelate ring conformation are simply controlled by protected/free hydroxyl groups of the sugar moiety, yielding mirror image CD spectra. In this system, repulsive and attractive forces are used to regulate chirality on the copper-coordinated oxygen atom both in the solid state and in solution.

  18. Surface chemistry of boron-doped SiO{sub 2} CVD: Enhanced uptake of tetraethyl orthosilicate by hydroxyl groups bonded to boron

    SciTech Connect

    Bartram, M.E.; Moffat, H.K.

    1993-12-31

    Insight into how dopants can enhance deposition rates has been obtained by comparing reactivities of tetraethyl orthosilicate (TEOS, Si(OCH{sub 2}CH{sub 3}){sub 4}) with silanol and boranol groups on SiO{sub 2}. This comparison is relevant for boron-doped SiO{sub 2} film growth from TEOS and trimethyl borate (TMB, B(OCH{sub 3}){sub 3}) sources since boranols and silanols are expected to be present on surface during the (CVD). A silica substrate having coadsorbed deuterated silanols (SIOD) and boranols (BOD) was reacted with TEOS in a cold-wall reactor in the mTorr pressure regime at 1000K. Reactions were followed with Fourier transform infrared spectroscopy. Use of deuterated hydroxyls allowed consumption of hydroxyls by TEOS chemisorption to be distinguished from concurrent formation of SIOH and BOH that results from TEOS decomposition. It was found that TEOS reacts with BOD at twice the rate observed for SIOD demonstrating that hydroxyl groups bonded to boron increase the rate of TEOS chemisorption. Surface ethoxy groups produced by chemisorption of TEOS decompose at a slower rate in the presence of TMB decomposition products. Possible dependencies on reactor geometries and other deposition conditions may determine which of these two competing effects will control deposition rates. This may explain (in part) why the rate enhancement effect is not always observed in boron-doped SiO{sub 2} CVD processes.

  19. Atomic resolution structure of a lysine-specific endoproteinase from Lysobacter enzymogenes suggests a hydroxyl group bound to the oxyanion hole.

    PubMed

    Asztalos, Peter; Müller, Astrid; Hölke, Werner; Sobek, Harald; Rudolph, Markus G

    2014-07-01

    Lysobacter enzymogenes lysyl endoproteinase (LysC) is a trypsin-type serine protease with a high pH optimum that hydrolyses all Lys-Xaa peptide bonds. The high specificity of LysC renders it useful for biotechnological purposes. The K30R variant of a related lysyl endoproteinase from Achromobacter lyticus has favourable enzymatic properties that might be transferrable to LysC. To visualize structural differences in the substrate-binding sites, the crystal structures of wild-type and the K30R variant of LysC were determined. The mutation is located at a distance of 12 Å from the catalytic triad and subtly changes the surface properties of the substrate-binding site. The high pH optimum of LysC can be attributed to electrostatic effects of an aromatic Tyr/His stack on the catalytic aspartate and is a general feature of this enzyme subfamily. LysC crystals in complex with the covalent inhibitor N(α)-p-tosyl-lysyl chloromethylketone yielded data to 1.1 and 0.9 Å resolution, resulting in unprecedented precision of the active and substrate-binding sites for this enzyme subfamily. Error estimates on bond lengths and difference electron density indicate that instead of the expected oxyanion a hydroxyl group binds to the partially solvent-exposed oxyanion hole. Protonation of the alkoxide catalytic intermediate might be a recurring feature during serine protease catalysis.

  20. Photocatalytic activity of Pt-TiO2 films supported on hydroxylated fly ash cenospheres under visible light

    NASA Astrophysics Data System (ADS)

    Wang, Bing; Yang, Zewei; An, Hao; Zhai, Jianping; Li, Qin; Cui, Hao

    2015-01-01

    TiO2 was coated on the surface of hydroxylated fly ash cenospheres (FACs) by the sol-gel method. Platinum (Pt) was then deposited on these TiO2/FAC particles by a photoreduction method to form PTF photocatalyst. The photocatalytic activity of PTF for the degradation of methylene blue (MB) under visible-light irradiation was determined. The PTF sample that was calcined at 450 °C and had a Pt/TiO2 mass ratio of 1.5% exhibited the optimal photocatalytic activity for degradation of MB with a catalyst concentration of 3 g L-1. MB was photodecomposed by PTF in aqueous solution more effectively at alkali pH than at acidic pH, because more MB molecules were adsorbed on the surface of PTF under alkaline conditions than that under acidic. The effect of various inorganic anions (HCO3-, F-, SO42-, NO3-, and Cl-) on the photodegradation of MB by PTF was also investigated. Addition of anions with a concentration of 5 mM enhanced the photocatalytic efficiency of PTF because of the improved adsorption of MB. This effect weakened as the anion concentration was increased, which was attributed to the ability of the anions to scavenge hydroxyl radicals and holes. Our results indicated that the photodegradation of MB took place mainly on the catalyst surface. The generation of hydroxyl radicals in the photocatalytic reaction was measured by the fluorescence method. KI was used to determine the participation of holes in the photocatalytic reaction. Both hydroxyl radicals and valence-band holes were detected in the PTF system. Recycling tests revealed that calcination of the used PTF helped to regain its photocatalytic activity.

  1. Membrane permeability of redox active metal chelators: an important element in reducing hydroxyl radical induced NAD+ depletion in neuronal cells.

    PubMed

    Jayasena, T; Grant, R S; Keerthisinghe, N; Solaja, I; Smythe, G A

    2007-03-01

    There is substantial evidence implicating increased production of the hydroxyl radical and oxidative stress in the pathogenesis of neurodegenerative diseases such as Alzheimer's disease (AD). Significant amounts of hydroxyl radicals will be produced in the presence of hydrogen peroxide and redox active iron via Fenton chemistry. Increased iron levels within the cytoplasm of vulnerable neurons suggest that this may also be an important site of oxidative activity. We investigated the likelihood that intracellular, rather than extracellular chelation of ferrous or ferric iron may be more effective in reducing hydroxyl radical induced cell damage and preserving NAD(+) levels and cell viability. Using intracellular NAD(H) measurements as an indicator of cell viability we found that membrane permeable ferrous chelators were most efficient in preserving cellular NAD(+) levels. Hydrophilic, ferrous or ferric chelators and lipophilic ferric chelators were essentially ineffective in preventing cellular NAD(+) depletion when added at physiological concentrations. We propose that lipophilic ferrous chelators, due to their actions inside the cell, are effective agents for moderating neuronal damage in conditions such as AD where intracellular oxidative stress plays a significant role in disease pathology. PMID:17210195

  2. Influence of lipids with hydroxyl-containing head groups on Fe2+ (Cu2+)/H2O2-mediated transformation of phospholipids in model membranes.

    PubMed

    Olshyk, Viktoriya N; Melsitova, Inna V; Yurkova, Irina L

    2014-01-01

    Under condition of ROS formation in lipid membranes, free radical reactions can proceed in both hydrophobic (peroxidation of lipids, POL) and polar (free radical fragmentation) parts of the bilayer. Free-radical fragmentation is typical for the lipids containing a hydroxyl group in β-position with respect to an ester or amide bond. The present study has been undertaken to investigate free-radical transformations of phospholipids in model membranes containing lipids able to undergo fragmentation in their polar part. Liposomes from egg yolk lecithin containing saturated or monounsaturated glycero- and sphingolipids were subjected to the action of an HO* - generating system - Fe(2+)(Cu(2+))/H2O2/Asc, and the POL products were investigated. In parallel with this, the effects of monoacylglycerols and scavengers of reactive species on Fe(2+)(Cu(2+))/H2O2/Asc - mediated free-radical fragmentation of phosphatidylglycerols were studied. Hydroxyl-containing sphingolipids and glycerolipids, which undergo free-radical fragmentation under such conditions, manifested antioxidant properties in the model membranes. In the absence of HO groups in the lipid structure, the effect was either pro-oxidant or neutral. Monoacylglycerols slowed down the rate of both peroxidation in the hydrophobic part and free-radical fragmentation in the hydrophilic part of phospholipid membrane. Scavengers of reactive species inhibited the fragmentation of phosphatidylglycerol substantially. Thus, the ability of hydroxyl-containing lipids to undergo free-radical fragmentation in polar part apparently makes a substantial contribution to the mechanism of their protector action. PMID:24189590

  3. Influence of lipids with hydroxyl-containing head groups on Fe2+ (Cu2+)/H2O2-mediated transformation of phospholipids in model membranes.

    PubMed

    Olshyk, Viktoriya N; Melsitova, Inna V; Yurkova, Irina L

    2014-01-01

    Under condition of ROS formation in lipid membranes, free radical reactions can proceed in both hydrophobic (peroxidation of lipids, POL) and polar (free radical fragmentation) parts of the bilayer. Free-radical fragmentation is typical for the lipids containing a hydroxyl group in β-position with respect to an ester or amide bond. The present study has been undertaken to investigate free-radical transformations of phospholipids in model membranes containing lipids able to undergo fragmentation in their polar part. Liposomes from egg yolk lecithin containing saturated or monounsaturated glycero- and sphingolipids were subjected to the action of an HO* - generating system - Fe(2+)(Cu(2+))/H2O2/Asc, and the POL products were investigated. In parallel with this, the effects of monoacylglycerols and scavengers of reactive species on Fe(2+)(Cu(2+))/H2O2/Asc - mediated free-radical fragmentation of phosphatidylglycerols were studied. Hydroxyl-containing sphingolipids and glycerolipids, which undergo free-radical fragmentation under such conditions, manifested antioxidant properties in the model membranes. In the absence of HO groups in the lipid structure, the effect was either pro-oxidant or neutral. Monoacylglycerols slowed down the rate of both peroxidation in the hydrophobic part and free-radical fragmentation in the hydrophilic part of phospholipid membrane. Scavengers of reactive species inhibited the fragmentation of phosphatidylglycerol substantially. Thus, the ability of hydroxyl-containing lipids to undergo free-radical fragmentation in polar part apparently makes a substantial contribution to the mechanism of their protector action.

  4. Can the conformation of flexible hydroxyl groups be constrained by simple NMR crystallography approaches? The case of the quercetin solid forms.

    PubMed

    Filip, Xenia; Filip, Claudiu

    2015-02-01

    Hydrogen atoms in systems with many flexible hydroxyl side-groups are difficult to be exactly located from experimental X-Ray diffraction and/or solid-state NMR data, thus often leading to wrong conclusions with respect to the hydrogen bonding network established in crystal lattice. A simple computational method is proposed in the present work to tackle this problem, which may be readily incorporated in conventional NMR crystallography protocols. The method is based on ranking all possible conformations of the flexible hydroxyls according to their lattice energy in crystalline environments. Its effectiveness is investigated on two distinct solid forms of quercetin, for which only two out of the five hydroxyl side-groups can be well constrained from experimental/theoretical data. For this purpose, first-principle quantum-mechanical computations were combined with calculations at the molecular mechanics (MM) level of theory, and previous ss-NMR and X-Ray diffraction data. To assess accuracy in ranking the identified conformers, tests have been performed first on quercetin dihydrate, for which an X-Ray single-crystal structure is available. The possibility of applying this method in a real NMR crystallography context has been investigated finally on anhydrous quercetin, for which only powder X-Ray crystal structure has been reported so far.

  5. Vibrational Study of Melatonin and its Radioprotective Activity towards Hydroxyl Radical

    NASA Astrophysics Data System (ADS)

    Singh, Gurpreet; Kaur, Sarvpreet; Saini, G. S. S.

    2011-12-01

    Vibrational study of Melatonin (N-acetyl 5-methoxytrypatamin) was done using FTIR and Raman spectroscopy. DFT calculations were employed to the structural analysis of melatonin and to the end products. The theoretical calculations confirmed the different observed vibrational modes. The optimized structure energy calculations of the different end products confirmed the most probable site of the hydroxyl radical attack is the hydrogen attached to nitrogen present in the indole ring.

  6. Structure-activity relationships in aminosterol antibiotics: the effect of stereochemistry at the 7-OH group.

    PubMed

    Tessema, Tsemre-Dingel; Gassler, Frank; Shu, Youheng; Jones, Stephen; Selinsky, Barry S

    2013-06-01

    Squalamine and three aminosterol analogs have been shown to inhibit bacterial cell growth and induce lysis of large unilamellar phospholipid vesicles. The analogs differ in the identity of the polyamine attached at C3 of the sterol, and the stereochemistry of a hydroxyl substituent at C7. Analogs with a tetraammonium spermine polyamine are somewhat more active than analogs with a shorter trisammonium spermidine polyamine, and analogs with an axial (α) hydroxyl substituent at C7 are more active than analogs with the corresponding equatorial (β) hydroxyl group. There is some variability noted; the 7β-OH spermine analog is the most active compound against Escherichia coli, but the least effective against Pseudomonas aeruginosa. Lytic activity correlates well with antimicrobial activity of the compounds, but the lytic activity varies with the phospholipid composition of the vesicles. PMID:23618624

  7. Replacement of the carboxylic acid group of prostaglandin F2α with a hydroxyl or methoxy substituent provides biologically unique compounds

    PubMed Central

    Woodward, D F; Krauss, A H-P; Chen, J; Gil, D W; Kedzie, K M; Protzman, C E; Shi, L; Chen, R; Krauss, H A; Bogardus, A; Dinh, H T T; Wheeler, L A; Andrews, S W; Burk, R M; Gac, T; Roof, M B; Garst, M E; Kaplan, L J; Sachs, G; Pierce, K L; Regan, J W; Ross, R A; Chan, M F

    2000-01-01

    Replacement of the carboxylic acid group of PGF2α with the non-acidic substituents hydroxyl (-OH) or methoxy (-OCH3) resulted in an unexpected activity profile.Although PGF2α 1-OH and PGF2α 1-OCH3 exhibited potent contractile effects similar to 17-phenyl PGF2α in the cat lung parenchymal preparation, they were approximately 1000 times less potent than 17-phenyl PGF2α in stimulating recombinant feline and human FP receptors.In human dermal fibroblasts and Swiss 3T3 cells PGF2α 1-OH and PGF2α 1-OCH3 produced no Ca2+ signal until a 1 μM concentration was exceeded. Pretreatment of Swiss 3T3 cells with either 1 μM PGF2α 1-OH or PGF2α 1-OCH3 did not attenuate Ca2+ signal responses produced by PGF2α or fluprostenol. In the rat uterus, PGF2α 1-OH was about two orders of magnitude less potent than 17-phenyl PGF2α whereas PGF2α 1-OCH3 produced only a minimal effect.Radioligand binding studies on cat lung parenchymal plasma membrane preparations suggested that the cat lung parenchyma does not contain a homogeneous population of receptors that equally respond to PGF2α1-OH, PGF2α1-OCH3, and classical FP receptor agonists.Studies on smooth muscle preparations and cells containing DP, EP1, EP2, EP3, EP4, IP, and TP receptors indicated that the activity of PGF2α 1-OH and PGF2α 1-OCH3 could not be ascribed to interaction with these receptors.The potent effects of PGF2α 1-OH and PGF2α 1-OCH3 on the cat lung parenchyma are difficult to describe in terms of interaction with the FP or any other known prostanoid receptor. PMID:10952685

  8. Dehydration and Stabilization of a Reactive Tertiary Hydroxyl Group in Solid Oral Dosage Forms of BMS-779788.

    PubMed

    Adams, Monica L; Sharma, Vijayata; Gokhale, Madhushree; Huang, Yande; Stefanski, Kevin; Su, Ching; Hussain, Munir A

    2016-04-01

    BMS-779788 contains a reactive tertiary hydroxyl attached to a weakly basic imidazole ring. Propensity of the carbinol toward dehydration to yield the corresponding alkene, BMS-779788-ALK, was evaluated. Elevated levels of BMS-779788-ALK were observed in excipient compatibility samples. Stability studies revealed that BMS-779788 degrades to BMS-779788-ALK in capsules and tablets prepared by both dry and wet granulation processes. An acid-catalyzed dehydration mechanism, in which the heterocyclic core contributes resonance stability to the cationic intermediate via charge transfer to the imidazole ring, was proposed. Therefore, neutralization via a buffered (pH 7.0) granulating solution was used to mitigate dehydration. Solution studies revealed degradation of BMS-779788 to BMS-779788-ALK over the pH range of 1-7.5. Reversibility was confirmed by initiating reactions with BMS-779788-ALK over the same pH range. Accordingly, a simple reversible scheme can be used to describe reactions initiated with either BMS-779788 or BMS-779788-ALK. To eliminate potential for charge delocalization across the heterocycle and probe the degradation mechanism, the imidazole ring of BMS-779788 was methylated (BMS-779788-Me). The propensity for acid-catalyzed dehydration was then evaluated. The acid stability of BMS-779788-Me confirmed that the heterocyclic core contributes to reactivity liability of the tertiary hydroxyl. PMID:26921118

  9. Dehydration and Stabilization of a Reactive Tertiary Hydroxyl Group in Solid Oral Dosage Forms of BMS-779788.

    PubMed

    Adams, Monica L; Sharma, Vijayata; Gokhale, Madhushree; Huang, Yande; Stefanski, Kevin; Su, Ching; Hussain, Munir A

    2016-04-01

    BMS-779788 contains a reactive tertiary hydroxyl attached to a weakly basic imidazole ring. Propensity of the carbinol toward dehydration to yield the corresponding alkene, BMS-779788-ALK, was evaluated. Elevated levels of BMS-779788-ALK were observed in excipient compatibility samples. Stability studies revealed that BMS-779788 degrades to BMS-779788-ALK in capsules and tablets prepared by both dry and wet granulation processes. An acid-catalyzed dehydration mechanism, in which the heterocyclic core contributes resonance stability to the cationic intermediate via charge transfer to the imidazole ring, was proposed. Therefore, neutralization via a buffered (pH 7.0) granulating solution was used to mitigate dehydration. Solution studies revealed degradation of BMS-779788 to BMS-779788-ALK over the pH range of 1-7.5. Reversibility was confirmed by initiating reactions with BMS-779788-ALK over the same pH range. Accordingly, a simple reversible scheme can be used to describe reactions initiated with either BMS-779788 or BMS-779788-ALK. To eliminate potential for charge delocalization across the heterocycle and probe the degradation mechanism, the imidazole ring of BMS-779788 was methylated (BMS-779788-Me). The propensity for acid-catalyzed dehydration was then evaluated. The acid stability of BMS-779788-Me confirmed that the heterocyclic core contributes to reactivity liability of the tertiary hydroxyl.

  10. Preparation of hydroxylated polyethylene surfaces.

    PubMed

    Zand, A; Walter, N; Bahu, M; Ketterer, S; Sanders, M; Sikorski, Y; Cunningham, R; Beholz, L

    2008-01-01

    The surfaces of high-density or ultra-high-molecular-weight polyethylenes were hydroxylated using a two-step process. The wetting and wear properties of the untreated (virgin) and surface hydroxylated polyethylenes were compared. The introduction of hydroxyl groups provided an increase in surface hydrophilicity resulting in reduced wear. Hydrophilicity was analyzed by optical analysis of water contact angle. Wear was determined by weight loss under conditions of a reciprocating pin-on-plate apparatus with the panels immersed in water or calf serum. These results suggest that hydroxylation of polyethylene friction-bearing orthopedic surfaces may lead to a longer joint life. PMID:18318959

  11. Variation in optoelectronic properties of azo dye-sensitized TiO2 semiconductor interfaces with different adsorption anchors: carboxylate, sulfonate, hydroxyl and pyridyl groups.

    PubMed

    Zhang, Lei; Cole, Jacqueline M; Dai, Chencheng

    2014-05-28

    The optoelectronic properties of four azo dye-sensitized TiO2 interfaces are systematically studied as a function of a changing dye anchoring group: carboxylate, sulfonate, hydroxyl, and pyridyl. The variation in optoelectronic properties of the free dyes and those in dye/TiO2 nanocomposites are studied both experimentally and computationally, in the context of prospective dye-sensitized solar cell (DSSC) applications. Experimental UV/vis absorption spectroscopy, cyclic voltammetry, and DSSC device performance testing reveal a strong dependence on the nature of the anchor of the optoelectronic properties of these dyes, both in solution and as dye/TiO2 nanocomposites. First-principles calculations on both an isolated dye/TiO2 cluster model (using localized basis sets) and each dye modeled onto the surface of a 2D periodic TiO2 nanostructure (using plane wave basis sets) are presented. Detailed examination of these experimental and computational results, in terms of light harvesting, electron conversion and photovoltaic device performance characteristics, indicates that carboxylate is the best anchoring group, and hydroxyl is the worst, whereas sulfonate and pyridyl groups exhibit competing potential. Different sensitization solvents are found to affect critically the extent of dye adsorption achieved in the dye-sensitization of the TiO2 semiconductor, especially where the anchor is a pyridyl group.

  12. The effect of ethanol on hydroxyl and carbonyl groups in biopolyol produced by hydrothermal liquefaction of loblolly pine: (31)P-NMR and (19)F-NMR analysis.

    PubMed

    Celikbag, Yusuf; Via, Brian K; Adhikari, Sushil; Buschle-Diller, Gisela; Auad, Maria L

    2016-08-01

    The goal of this study was to investigate the role of ethanol and temperature on the hydroxyl and carbonyl groups in biopolyol produced from hydrothermal liquefaction of loblolly pine (Pinus spp.) carried out at 250, 300, 350 and 390°C for 30min. Water and water/ethanol mixture (1/1, wt/wt) were used as liquefying solvent in the HTL experiments. HTL in water and water/ethanol is donated as W-HTL and W/E-HTL, respectively. It was found that 300°C and water/ethanol solvent was the optimum liquefaction temperature and solvent, yielding up to 68.1wt.% bio-oil and 2.4wt.% solid residue. (31)P-NMR analysis showed that biopolyol produced by W-HTL was rich in phenolic OH while W/E-HTL produced more aliphatic OH rich biopolyols. Moreover, biopolyols with higher hydroxyl concentration were produced by W/E-HTL. Carbonyl groups were analyzed by (19)F-NMR, which showed that ethanol reduced the concentration of carbonyl groups. PMID:27126078

  13. The effect of ethanol on hydroxyl and carbonyl groups in biopolyol produced by hydrothermal liquefaction of loblolly pine: (31)P-NMR and (19)F-NMR analysis.

    PubMed

    Celikbag, Yusuf; Via, Brian K; Adhikari, Sushil; Buschle-Diller, Gisela; Auad, Maria L

    2016-08-01

    The goal of this study was to investigate the role of ethanol and temperature on the hydroxyl and carbonyl groups in biopolyol produced from hydrothermal liquefaction of loblolly pine (Pinus spp.) carried out at 250, 300, 350 and 390°C for 30min. Water and water/ethanol mixture (1/1, wt/wt) were used as liquefying solvent in the HTL experiments. HTL in water and water/ethanol is donated as W-HTL and W/E-HTL, respectively. It was found that 300°C and water/ethanol solvent was the optimum liquefaction temperature and solvent, yielding up to 68.1wt.% bio-oil and 2.4wt.% solid residue. (31)P-NMR analysis showed that biopolyol produced by W-HTL was rich in phenolic OH while W/E-HTL produced more aliphatic OH rich biopolyols. Moreover, biopolyols with higher hydroxyl concentration were produced by W/E-HTL. Carbonyl groups were analyzed by (19)F-NMR, which showed that ethanol reduced the concentration of carbonyl groups.

  14. Detection and measurement of the agonistic activities of PCBs and mono-hydroxylated PCBs to the constitutive androstane receptor using a recombinant yeast assay.

    PubMed

    Kamata, Ryo; Shiraishi, Fujio; Kageyama, Shiho; Nakajima, Daisuke

    2015-10-01

    Polychlorinated biphenyls (PCBs) are thought to exert their toxicities mainly by binding to the aryl hydrocarbon receptor and by stimulating transcription of various genes, notably metabolizing enzymes including the cytochrome P450 (CYP) 1 family. However, PCBs and their metabolites could have potential to activate other nuclear receptors and subsequent events. We focused on the constitutive androstane receptor (CAR) inducing CYP2B and measured the agonistic activity of PCBs and mono-hydroxylated PCBs (OH-PCBs) to the CAR using yeast cells transduced with the human CAR and its response pathway. Twenty-nine of 34 tested PCBs and 72 of 91 OH-PCBs exhibited CAR agonistic effects. Of 41 OH-PCBs that had the same chlorination patterns as the tested PCBs, 9 had activities more than twice those of their non-hydroxylated analogs. In particular, 2',4',6'-trichlorobiphenyl-4-ol and 2,2',4',6'-tetrachlorobiphenyl-4-ol were 332- and 22-fold more potent than their analogs and were 15 times and 2.8 times, respectively, as active as a reference substance, 4-tert-octylphenol. The activities of 17 of the OH-PCBs were reduced to less than half those of their non-hydroxylated analogs. Four OH-PCBs derived from 3 active PCBs were inactive. However, a consistent relationship between hydroxyl substituent position and activity could not be discerned. Comprehensive evaluation of the toxic potential of PCBs and their hydroxylated metabolites and their concentrations in the environment are required.

  15. Detection analysis of surface hydroxyl active sites and simulation calculation of the surface dissociation constants of aqueous diatomite suspensions

    NASA Astrophysics Data System (ADS)

    Ma, Shu-Cui; Wang, Zhi-Gang; Zhang, Ji-Lin; Sun, De-Hui; Liu, Gui-Xia

    2015-02-01

    The surface properties of the diatomite were investigated using nitrogen adsorption/deadsorption isotherms, TG-DSC, FTIR, and XPS, and surface protonation-deprotonation behavior was determined by continuous acid-base potentiometric titration technique. The diatomite sample with porous honeycomb structure has a BET specific surface area of 10.21 m2/g and large numbers of surface hydroxyl functional groups (i.e. tbnd Si-OH, tbnd Fe-OH, and tbnd Al-OH). These surface hydroxyls can be protonated or deprotonated depending on the pH of the suspension. The experimental potentiometric data in two different ionic strength solutions (0.1 and 0.05 mol/L NaCl) were fitted using ProtoFit GUI V2.1 program by applying diffuse double layer model (DLM) with three amphoteric sites and minimizing the sum of squares between a dataset derivative function and a model derivative function. The optimized surface parameters (i.e. surface dissociation constants (log K1, log K2) and surface site concentrations (log C)) of the sample were obtained. Based on the optimized surface parameters, the surface species distribution was calculated using Program-free PHREEQC 3.1.2. Thus, this work reveals considerable new information about surface protonation-deprotonation processes and surface adsorptive behaviors of the diatomite, which helps us to effectively use the cheap and cheerful diatomite clay adsorbent.

  16. Preferential adsorption behavior of methylene blue dye onto surface hydroxyl group enriched TiO2 nanotube and its photocatalytic regeneration.

    PubMed

    Natarajan, Thillai Sivakumar; Bajaj, Hari C; Tayade, Rajesh J

    2014-11-01

    The present manuscript focus on the synthesis of surface hydroxyl group enriched titanium dioxide nanotube (TNT) by hydrothermal method for preferential adsorption of methylene blue (MB) dye. The mixture of methylene blue (MB) and rhodamine B (RhB) dye was used to study the preferential adsorption nature of TNT. The synthesized TNT were characterized by various techniques such as powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption, and ammonia-temperature programmed desorption (NH3-TPD) analysis. Result demonstrated that enhancement in the surface area of TNT and higher number of hydroxyl group on the surface of TNT. In the binary mixture, the adsorption of MB dye was 12.9 times higher as compared to RhB dye, which clearly indicated the preferential adsorption of MB dye on TNT surface. The preferential interaction of MB on TNT is due to the electrostatic interaction between the cationic MB and negatively charged TNT surface. The preferential adsorption of MB dye was studied by applying Langmuir, Freundlich and Sips isotherm; pseudo-first and second-order kinetic model. Furthermore, the regeneration of dye adsorbed TNT was carried out by eco-friendly photocatalytic process under the irradiation of ultraviolet light.

  17. Photo and Chemical Reduction of Copper onto Anatase-Type TiO2 Nanoparticles with Enhanced Surface Hydroxyl Groups as Efficient Visible Light Photocatalysts.

    PubMed

    Eskandarloo, Hamed; Badiei, Alireza; Behnajady, Mohammad A; Mohammadi Ziarani, Ghodsi

    2015-01-01

    In this study, the photocatalytic efficiency of anatase-type TiO2 nanoparticles synthesized using the sol-gel low-temperature method, were enhanced by a combined process of copper reduction and surface hydroxyl groups enhancement. UV-light-assisted photo and NaBH4 -assisted chemical reduction methods were used for deposition of copper onto TiO2. The surface hydroxyl groups of TiO2 were enhanced with the assistance of NaOH modification. The prepared catalysts were immobilized on glass plates and used as the fixed-bed systems for the removal of phenazopyridine as a model drug contaminant under visible light irradiation. NaOH-modified Cu/TiO2 nanoparticles demonstrated higher photocatalytic efficiency than that of pure TiO2 due to the extending of the charge carriers lifetime and enhancement of the adsorption capacity of TiO2 toward phenazopyridine. The relationship of structure and performance of prepared nanoparticles has been established by using various techniques, such as XRD, XPS, TEM, EDX, XRF, TGA, DRS and PL. The effects of preparation variables, including copper content, reducing agents rate (NaBH4 concentration and UV light intensity) and NaOH concentration were investigated on the photocatalytic efficiency of NaOH-modified Cu/TiO2 nanoparticles.

  18. Interaction of Gold Clusters with a Hydroxylated Surface

    SciTech Connect

    Jiang, Deen; Overbury, Steven {Steve} H; Dai, Sheng

    2011-01-01

    We explore the interaction between gold nanoclusters and a fully hydroxylated surface, Mg(OH){sub 2}'s basal plane, by using a density functional theory-enabled local basin-hopping technique for global-minimum search. We find strong interaction of gold nanoclusters with the surface hydroxyls via a short bond between edge Au atoms and O atoms of the -OH groups. We expect that this strong interaction is ubiquitous on hydroxylated support surfaces and helps the gold nanoclusters against sintering, thereby contributing to their CO-oxidation activity at low temperatures.

  19. A comparative study of the hydroxyl radical scavenging capacity of activated sludge and membrane bioreactor wastewater effluents.

    PubMed

    Grant, Jacque-Ann; Hofmann, Ron

    2016-01-01

    This study evaluated the hydroxyl radical scavenging characteristics of wastewater from five membrane bioreactor (MBR) and five activated sludge (AS) systems. The average values of the characteristics of both wastewater types was found to be significantly different at a 90% confidence interval in terms UV absorbance at 254 nm, alkalinity, and biopolymer concentration. Effluent organic matter (EfOM), with an average kOH,EfOM of (2.75 ± 1.04) × 10(8) M(-1)s(-1), was identified as the primary hydroxyl scavenger contributing to >70% of the background scavenging in all cases, except when nitrite exceeded 0.3 mg NO(2)(-)-N/L. The average scavenging capacity, EfOM scavenging capacity, and the EfOM reaction rate constant of the AS wastewaters exceeded that of the MBR. However, due to the small sample size (n = 5) and considerable variability in scavenging characteristics among the MBR wastewaters, the difference in EfOM reactivity between the two wastewaters was not statistically significant at a 90% confidence interval. Nevertheless, these preliminary findings suggest the possibility that MBR wastewaters may be more amenable to treatment by advanced oxidation. A plausible explanation is that MBRs were observed to reject biopolymers, and a strong correlation was observed between EfOM scavenging capacity and biopolymer concentration.

  20. ESSENTIAL ROLE OF SURFACE HYDROXYLS FOR THE STABILIZATION AND CATALYTIC ACTIVITY OF TiO2-SUPPORTED GOLD NANOPARTICLES

    SciTech Connect

    Veith, Gabriel M; Lupini, Andrew R; Dudney, Nancy J

    2009-01-01

    We report the investigation of titania supported gold catalysts prepared by magnetron sputtering. Catalysts grown on natural fumed titania were structurally unstable resulting in the rapid coarsening of 2.3 nm gold clusters into large ~20 nm gold clusters in a few days at room temperature under normal atmospheric conditions. However, treating the titania support powder to a mock-deposition-precipitation process, at pH 4 or pH 10, followed by the subsequent deposition of gold onto this treated powder produced a remarkable enhancement in gold particle stability and a 20-40 fold enhancement of catalytic activity respectively. This enhancement can not be attributed to the formation of oxygen vacancies on the TiO2 surface. Instead, it appears to be associated with the formation of strongly bound hydroxyl species on the TiO2 surface. The formation of surface hydroxyls during the deposition-precipitation method is coincidental and contributes significantly to the properties of Au/TiO2 catalysts.

  1. A comparative study of the hydroxyl radical scavenging capacity of activated sludge and membrane bioreactor wastewater effluents.

    PubMed

    Grant, Jacque-Ann; Hofmann, Ron

    2016-01-01

    This study evaluated the hydroxyl radical scavenging characteristics of wastewater from five membrane bioreactor (MBR) and five activated sludge (AS) systems. The average values of the characteristics of both wastewater types was found to be significantly different at a 90% confidence interval in terms UV absorbance at 254 nm, alkalinity, and biopolymer concentration. Effluent organic matter (EfOM), with an average kOH,EfOM of (2.75 ± 1.04) × 10(8) M(-1)s(-1), was identified as the primary hydroxyl scavenger contributing to >70% of the background scavenging in all cases, except when nitrite exceeded 0.3 mg NO(2)(-)-N/L. The average scavenging capacity, EfOM scavenging capacity, and the EfOM reaction rate constant of the AS wastewaters exceeded that of the MBR. However, due to the small sample size (n = 5) and considerable variability in scavenging characteristics among the MBR wastewaters, the difference in EfOM reactivity between the two wastewaters was not statistically significant at a 90% confidence interval. Nevertheless, these preliminary findings suggest the possibility that MBR wastewaters may be more amenable to treatment by advanced oxidation. A plausible explanation is that MBRs were observed to reject biopolymers, and a strong correlation was observed between EfOM scavenging capacity and biopolymer concentration. PMID:27148707

  2. Hormone Activity of Hydroxylated Polybrominated Diphenyl Ethers on Human Thyroid Receptor-β: In Vitro and In Silico Investigations

    PubMed Central

    Li, Fei; Xie, Qing; Li, Xuehua; Li, Na; Chi, Ping; Chen, Jingwen; Wang, Zijian; Hao, Ce

    2010-01-01

    Background Hydroxylated polybrominated diphenyl ethers (HO-PBDEs) may disrupt thyroid hormone status because of their structural similarity to thyroid hormone. However, the molecular mechanisms of interactions with thyroid hormone receptors (TRs) are not fully understood. Objectives We investigated the interactions between HO-PBDEs and TRβ to identify critical structural features and physicochemical properties of HO-PBDEs related to their hormone activity, and to develop quantitative structure–activity relationship (QSAR) models for the thyroid hormone activity of HO-PBDEs. Methods We used the recombinant two-hybrid yeast assay to determine the hormone activities to TRβ and molecular docking to model the ligand–receptor interaction in the binding site. Based on the mechanism of action, molecular structural descriptors were computed, selected, and employed to characterize the interactions, and finally a QSAR model was constructed. The applicability domain (AD) of the model was assessed by Williams plot. Results The 18 HO-PBDEs tested exhibited significantly higher thyroid hormone activities than did PBDEs (p < 0.05). Hydrogen bonding was the characteristic interaction between HO-PBDE molecules and TRβ, and aromaticity had a negative effect on the thyroid hormone activity of HO-PBDEs. The developed QSAR model had good robustness, predictive ability, and mechanism interpretability. Conclusions Hydrogen bonding and electrostatic interactions between HO-PBDEs and TRβ are important factors governing thyroid hormone activities. The HO-PBDEs with higher ability to accept electrons tend to have weak hydrogen bonding with TRβ and lower thyroid hormone activities. PMID:20439171

  3. 3-(4'-hydroxyl-3',5'-dimethoxyphenyl)propionic acid, an active principle of kimchi, inhibits development of atherosclerosis in rabbits.

    PubMed

    Kim, Hyun Ju; Lee, Jin Su; Chung, Hae Young; Song, Su Hee; Suh, Hongsuk; Noh, Jung Sook; Song, Yeong Ok

    2007-12-12

    The effects of 3-(4'-hydroxyl-3',5'-dimethoxyphenyl)propionic acid (HDMPPA) originating from Korean cabbage kimchi were investigated, showing an antioxidant effect on the prevention of atherosclerosis in hypercholesterolemic rabbits. Twenty-one 3-month-old rabbits were fed an atherogenic diet containing 0.5% (w/w) cholesterol and 10% (w/w) coconut oil, whereas another two groups were given an atherogenic diet with intravenous injection of either HDMPPA or simvastatin (0.33 mg/kg/day) for 4 weeks. HDMPPA inhibited the oxidative modification of low-density lipoprotein (IC 50 = 1.4 microg/mL) and increased 2,2'-diphenyl-1-picrylhydrazyl radical scavenging activity (IC 50 = 0.78 microg/mL) in a dose-dependent manner. In hypercholesterolemic rabbits, the thickness of intima of aorta of the HDMPPA group was significantly reduced (control versus HDMPPA, 42%; simvastatin, 38%) without a plasma cholesterol-lowering effect. Thiobarbituric acid reactive substance formation in the plasma of the HDMPPA group was significantly decreased compared to that of the control group. Furthermore, the generation of vascular reactive oxygen species in HDMPPA group was suppressed as the cyclooxygenase-2 protein level decreased. These findings suggest that HDMPPA prevents the development of aortic atherosclerosis in high-cholesterol-fed rabbits. The antiatherosclerotic effect of HDMPPA may be due to an antioxidative effect at a low dose without cholesterol-lowering effects. PMID:18004805

  4. Manganese Catalysts for C–H activation: An Experimental/Theoretical Study Identifies the Stereoelectronic Factor that Controls the Switch between Hydroxylation and Desaturation Pathways

    PubMed Central

    Hull, Jonathan F.; Balcells, David; Sauer, Effiette L. O.; Raynaud, Christophe; Brudvig, Gary W.; Crabtree, Robert H.; Eisenstein, Odile

    2010-01-01

    We describe competitive C–H activation chemistry of two types, desaturation and hydroxylation, using synthetic manganese catalysts with several substrates. 9,10-dihydrophenanthrene (DHP) gives the highest desaturation activity, the final products being phenanthrene (P1) and phenanthrene-9,10-oxide (P3), the latter being thought to arise from epoxidation of some of the phenanthrene. The hydroxylase pathway also occurs as suggested by the presence of the dione product, phenanthrene-9,10-dione (P2), thought to arise from further oxidation of hydroxylation intermediate 9-hydroxy-9,10-dihydrophenanthrene. The experimental work together with the DFT calculations shows that the postulated Mn oxo active species, [Mn(O)(tpp)(Cl)] (tpp = tetraphenyl porphyrin), can promote the oxidation of dihydrophenanthrene by either desaturation or hydroxylation pathways. The calculations show that these two competing reactions have a common initial step – radical H abstraction from one of the DHP sp3 C–H bonds. The resulting Mn hydroxo intermediate is capable of promoting not only OH rebound (hydroxylation) but also a second H abstraction adjacent to the first (desaturation). Like the active MnV=O species, this MnIV-OH species also has radical character on oxygen and can thus give H abstraction. Both steps have very low and therefore very similar energy barriers, leading to a product mixture. Since the radical character of the catalyst is located on the oxygen p orbital perpendicular to the MnIV-OH plane, the orientation of the organic radical with respect to this plane determines which reaction, desaturation or hydroxylation, will occur. Stereoelectronic factors such as the rotational orientation of the OH in the enzyme active site is thus likely to constitute the switch between hydroxylation and desaturation behavior. PMID:20481432

  5. Molecular docking and 3D-QSAR studies on the glucocorticoid receptor antagonistic activity of hydroxylated polychlorinated biphenyls.

    PubMed

    Liu, S; Luo, Y; Fu, J; Zhou, J; Kyzas, G Z

    2016-01-01

    The glucocorticoid receptor (GR) antagonistic activities of hydroxylated polychlorinated biphenyls (HO-PCBs) were recently characterised. To further explore the interactions between HO-PCBs and the GR, and to elucidate structural characteristics that influence the GR antagonistic activity of HO-PCBs, molecular docking and three-dimensional quantitative structure-activity relationship (3D-QSAR) studies were performed. Comparative molecular similarity indices analysis (CoMSIA) was performed using both ligand- and receptor-based alignment schemes. Results generated from the receptor-based model were found to be more satisfactory, with q(2) of 0.632 and r(2) of 0.931 compared with those from the ligand-based model. Some internal validation strategies (e.g. cross-validation analysis, bootstrapping analysis and Y-randomisation) and an external validation method were used respectively to further assess the stability and predictive ability of the derived model. Graphical interpretation of the model provided some insights into the structural features that affected the GR antagonistic activity of HO-PCBs. Molecular docking studies revealed that some key residues were critical for ligand-receptor interactions by forming hydrogen bonds (Glu540) and hydrophobic interactions with ligands (Ile539, Val543 and Trp577). Although CoMSIA sometimes depends on the alignment of the molecules, the information provided is beneficial for predicting the GR antagonistic activities of HO-PCB homologues and is helpful for understanding the binding mechanisms of HO-PCBs to GR. PMID:26848875

  6. Infrared spectroscopy of OD vibrators in minerals at natural dilution: hydroxyl groups in talc and kaolinite, and structural water in beryl and emerald.

    PubMed

    de Donato, Philippe; Cheilletz, Alain; Barres, Odile; Yvon, Jacques

    2004-05-01

    An infrared (IR) study of natural deuteration is conducted on minerals containing hydroxyl groups (talc and kaolinite) and channel-water-bearing minerals (beryl and emerald). In talc, the OD valence vibration is located at 2710 cm(-1), corresponding to OD groups surrounded by 3 Mg atoms. In kaolinite, the OD valence vibrations are located at 2671 cm(-1) (inner OD group), 2712, 2706, and 2700 cm(-1) (three inner-surface OD groups). In beryl and emerald, natural deuteration of channel water is observed for the first time by infrared microspectroscopy. In beryl from Minas Gerais (Brazil), the OD profiles are characterized by four bands at 2735, 2686, 2672, and 2641 cm(-1). In emeralds from Colombia and Brazil, the OD profiles are characterized by five or four bands, respectively, at 2816, 2737, 2685, 2673, and 2641 cm(-1) (Colombia) and 2730, 2684, 2672, and 2640 cm(-1) (Brazil). The band at 2816 cm(-1) can be assigned to -OD or OD(-), and bands at 2686-2684, 2673-2672, and 2641-2640 cm(-1) can be assigned to type-I and type-II HOD molecules. The band at 2737-2730 cm(-1) is partially disturbed by combination bands of the mineral. Such OD profiles are different from those obtained by artificial deuteration at higher OD dilution. PMID:15165327

  7. Infrared spectroscopy of OD vibrators in minerals at natural dilution: hydroxyl groups in talc and kaolinite, and structural water in beryl and emerald.

    PubMed

    de Donato, Philippe; Cheilletz, Alain; Barres, Odile; Yvon, Jacques

    2004-05-01

    An infrared (IR) study of natural deuteration is conducted on minerals containing hydroxyl groups (talc and kaolinite) and channel-water-bearing minerals (beryl and emerald). In talc, the OD valence vibration is located at 2710 cm(-1), corresponding to OD groups surrounded by 3 Mg atoms. In kaolinite, the OD valence vibrations are located at 2671 cm(-1) (inner OD group), 2712, 2706, and 2700 cm(-1) (three inner-surface OD groups). In beryl and emerald, natural deuteration of channel water is observed for the first time by infrared microspectroscopy. In beryl from Minas Gerais (Brazil), the OD profiles are characterized by four bands at 2735, 2686, 2672, and 2641 cm(-1). In emeralds from Colombia and Brazil, the OD profiles are characterized by five or four bands, respectively, at 2816, 2737, 2685, 2673, and 2641 cm(-1) (Colombia) and 2730, 2684, 2672, and 2640 cm(-1) (Brazil). The band at 2816 cm(-1) can be assigned to -OD or OD(-), and bands at 2686-2684, 2673-2672, and 2641-2640 cm(-1) can be assigned to type-I and type-II HOD molecules. The band at 2737-2730 cm(-1) is partially disturbed by combination bands of the mineral. Such OD profiles are different from those obtained by artificial deuteration at higher OD dilution.

  8. A statistical description of the evolution of cloud condensation nuclei activity during the heterogeneous oxidation of squalane and bis(2-ethylhexyl) sebacate aerosol by hydroxyl radicals.

    PubMed

    Harmon, Christopher W; Ruehl, Christopher R; Cappa, Christopher D; Wilson, Kevin R

    2013-06-28

    The heterogeneous reaction of hydroxyl radicals with chemically reduced organic aerosol comprised of either squalane or bis(2-ethylhexyl) sebacate are used as model systems to examine how cloud condensation nuclei (CCN) activity evolves with photochemical oxidation. Over the course of the reaction, the critical super-saturation evolves both by the formation of new oxygen functional groups and by changes in aerosol size through the formation of gas phase reaction products. A statistical model of the heterogeneous reaction reveals that it is the formation, volatilization, solubility, and surface activity of many generations of oxidation products that together control the average changes in aerosol hygroscopicity. The experimental observations and model demonstrate the importance of considering the underlying population or subpopulation of species within a particle and how they each uniquely contribute to the average hygroscopicity of a multi-component aerosol. To accurately predict changes in CCN activity upon oxidation requires a reduction in the surface tension of the activating droplet by a subpopulation of squalane reaction products. These results provide additional evidence that surface tension-concentration parameterizations based on macroscopic data should be modified for microscopic droplets.

  9. Transesterification of PHA to Oligomers Covalently Bonded with (Bio)Active Compounds Containing Either Carboxyl or Hydroxyl Functionalities

    PubMed Central

    Kwiecień, Iwona; Radecka, Iza; Kowalczuk, Marek; Adamus, Grażyna

    2015-01-01

    This manuscript presents the synthesis and structural characterisation of novel biodegradable polymeric controlled-release systems of pesticides with potentially higher resistance to weather conditions in comparison to conventional forms of pesticides. Two methods for the preparation of pesticide-oligomer conjugates using the transesterification reaction were developed. The first method of obtaining conjugates, which consist of bioactive compounds with the carboxyl group and polyhydroxyalkanoates (PHAs) oligomers, is "one-pot" transesterification. In the second method, conjugates of bioactive compounds with hydroxyl group and polyhydroxyalkanoates oligomers were obtained in two-step method, through cyclic poly(3-hydroxybutyrate) oligomers. The obtained pesticide-PHA conjugates were comprehensively characterised using GPC, 1H NMR and mass spectrometry techniques. The structural characterisation of the obtained products at the molecular level with the aid of mass spectrometry confirmed that both of the synthetic strategies employed led to the formation of conjugates in which selected pesticides were covalently bonded to PHA oligomers via a hydrolysable ester bond. PMID:25781908

  10. The Effect of Methyl, Hydroxyl, and Ketone Functional Groups on the Heterogeneous Oxidation of Succinic Acid Aerosol by OH Radicals

    NASA Astrophysics Data System (ADS)

    Chan, M.; Zhang, H.; Wilson, K. R.

    2013-12-01

    The heterogeneous oxidation of atmospheric organic aerosols can influence their effects on climate, human health, and visibility. During oxidation, functionalization occurs when an oxygenated functional group is added to a molecule, leaving the carbon skeleton intact. Fragmentation involves carbon-carbon bond cleavage and produces two products with smaller carbon numbers than the parent compound. To gain better insights into how the molecular structure of more oxygenated organic compounds affects heterogeneous reactivity, succinic acid aerosols are photo-oxidized in an aerosol flow tube reactor, and the reaction products are analyzed using Direct Analysis in Real Time Mass Spectrometry for online chemical analysis. The effect of various functional groups (CH3, OH, C=O) along the carbon backbone on the heterogeneous reaction mechanisms are also investigated using model compounds. For this series of compounds, the formation of more oxygenated products through functionalization can be explained by well-known condensation-phase reactions such as Russell and Bennett and Summers. The number of fragmentation products is found to increase with the presence of OH and CH3 groups. This can be attributed to the increased number of tertiary carbons, enhancing the fragmentation after multiple oxidation steps. Smaller dicaids (oxalic acid and malonic acid) can be formed through the fragmentation processes in the heterogeneous oxidation of succinic acid. The effect of molecular structure on reaction kinetics, volatilization, and the relative importance of functionalization and fragmentation pathways will be discussed.

  11. Hydroxylated analogues of the orally active broad spectrum antifungal, Sch 51048 (1), and the discovery of posaconazole [Sch 56592; 2 or (S,S)-5].

    PubMed

    Bennett, Frank; Saksena, Anil K; Lovey, Raymond G; Liu, Yi-Tsung; Patel, Naginbhai M; Pinto, Patrick; Pike, Russel; Jao, Edwin; Girijavallabhan, Viyyoor M; Ganguly, Ashit K; Loebenberg, David; Wang, Haiyan; Cacciapuoti, Anthony; Moss, Eugene; Menzel, Fred; Hare, Roberta S; Nomeir, Amin

    2006-01-01

    As part of a detailed study, the syntheses, biological activities, and pharmacokinetic properties of hydroxylated analogues of the previously described broad spectrum antifungal agents, Sch 51048 (1), Sch 50001 (3), and Sch 50002 (4), are described. Based on an overall superior profile, one of the alcohols, Sch 56592 (2), was selected for clinical studies.

  12. MEASUREMENT OF HYDROXYL RADICAL ACTIVITY IN A SOIL SLURRY USING THE SPIN TRAP A-(4-PYRIDYL-1-OXIDE)-N-TERT-BUTYLNITRONE

    EPA Science Inventory

    The spin trap compound a-(4-pyridyl-1-oxide)N-tert-butylnitrone (4-POBN) served as a probe to estimate the activity of Fenton-derived hydroxyl radicals (.OH) in a batch suspension comprised of silica sand and crushes goethite ore. The rate of probe disappearance was used to anal...

  13. Adsorption and desorption of DNA tuned by hydroxyl groups in graphite oxides-based solid extraction material.

    PubMed

    Akceoglu, Garbis Atam; Li, Oi Lun; Saito, Nagahiro

    2015-12-01

    The extraction of DNA is the most crucial method used in molecular biology. Up to date silica matrices has been widely applied as solid support for selective DNA adsorption and extraction. However, since adsorption force of SiOH functional groups is much greater than that of desorption force, the DNA extraction efficiency of silica surfaces is limited. In order to increase the DNA extraction yield, a new surface with different functional groups which possess of greater desorption property is required. In this study, we proposed cellulose/graphite oxide (GO) composite as an alternative material for DNA adsorption and extraction. GO/Cellulose composite provides the major adsorption and desorption of DNA by COH, which belongs to alkyl or phenol type of OH functional group. Compared to SiOH, COH is less polarized and reactive, therefore the composite might provide a higher desorption of DNA during the elution process. The GO/cellulose composite were prepared in spherical structure by mixing urea, cellulose, NaOH, Graphite oxide and water. The concentration of GO within the composites were controlled to be 0-4.15 wt.%. The extraction yield of DNA increased with increasing weight percentage of GO. The highest yield was achieved at 4.15 wt.% GO, where the extraction efficiency was reported as 660.4 ng/μl when applying 2M GuHCl as the binding buffer. The absorbance ratios between 260 nm and 280 nm (A260/A280) of the DNA elution was demonstrated as 1.86, indicating the extracted DNA consisted of high purity. The results proved that GO/cellulose composite provides a simple method for selective DNA extraction with high extraction efficiency of pure DNA.

  14. Synthesis and evaluation of antibacterial polyurethane coatings made from soybean oil functionalized with dimethylphenylammonium iodide and hydroxyl groups.

    PubMed

    Bakhshi, Hadi; Yeganeh, Hamid; Mehdipour-Ataei, Shahram

    2013-06-01

    Preparation of antibacterial polyurethane coatings from novel functional soybean oil was considered in this work. First, epoxidized soybean oil (ESBO) as a low price and widely available renewable resource raw material was subjected to the reaction with aniline using an ionic liquid as a green catalyst. The intermediate phenylamine containing polyol (SAP) was then methylated by reaction with methyl iodide to produce a polyol (QAP) with pendant dimethylphenylammonium iodide groups. To regulate the physical and mechanical properties as well as biological characteristics of final coatings, QAP was mixed with different portions of a similar soybean oil-based polyol (MSP) without quaternary ammonium groups. The mixtures were reacted with isophorone diisocyanate to produce crosslinked polyurethane coatings. Evaluation of viscoelastic properties by DMA method revealed single phase structure with Tg in the range of 50-82°C. Stress-strain analysis of the prepared polyurethanes showed initial modulus, tensile strength, and elongation at break in the ranges of 13-299 MPa, 4.5-13.8 MPa, and 16-109%, respectively. Additionally, the coatings showed good adherence to aluminum and PVC substrates. The solvent extracted samples showed excellent biocompatibility as determined by monitoring L929 fibroblast cells morphology and MTT assay. Meanwhile, very promising antibacterial properties against both Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria with bacterial reduction in the range of 83-100% was observed. PMID:23172859

  15. Infrared study of the interaction between Lewis bases and surface hydroxyl groups of {Pt}/{Cab-O-Sil}

    NASA Astrophysics Data System (ADS)

    Sárkány, János

    1997-06-01

    Transmission IR spectroscopic study at 298 K has revealed strong H-bonds between Lewis bases (LBs) containing one, [1-O], or two, [2-O], sp 3 hybridized O atoms and the surface OH groups of Cab-O-Sil. LB [1-O] (10 torr = 1.333 kPa) caused a greater | Δν(OH)| (470-520 cm -1) than did LB [2-O] (385-470 cm -1). In contrast with expectations, the intensity of the OH band at 3660 cm -1 decreased to a greater extent for LB [2-O] than for LB [1-O]. The results were interpreted on the basis of chargetransfer theory. The estimated sequence of electron-donating ability (EDA) was: oxepane > oxane > oxolane > diethyl ether ≥ 1,4-dioxane > 1,3-dioxepane > 1,3-dioxane > 1,3-dioxolane.

  16. Site-specific labeling of RNA at internal ribose hydroxyl groups: terbium-assisted deoxyribozymes at work.

    PubMed

    Büttner, Lea; Javadi-Zarnaghi, Fatemeh; Höbartner, Claudia

    2014-06-01

    A general and efficient single-step method was established for site-specific post-transcriptional labeling of RNA. Using Tb(3+) as accelerating cofactor for deoxyribozymes, various labeled guanosines were site-specifically attached to 2'-OH groups of internal adenosines in in vitro transcribed RNA. The DNA-catalyzed 2',5'-phosphodiester bond formation proceeded efficiently with fluorescent, spin-labeled, biotinylated, or cross-linker-modified guanosine triphosphates. The sequence context of the labeling site was systematically analyzed by mutating the nucleotides flanking the targeted adenosine. Labeling of adenosines in a purine-rich environment showed the fastest reactions and highest yields. Overall, practically useful yields >70% were obtained for 13 out of 16 possible nucleotide (nt) combinations. Using this approach, we demonstrate preparative labeling under mild conditions for up to ~160-nt-long RNAs, including spliceosomal U6 small nuclear RNA and a cyclic-di-AMP binding riboswitch RNA.

  17. Linear free energy relationships between aqueous phase hydroxyl radical reaction rate constants and free energy of activation.

    PubMed

    Minakata, Daisuke; Crittenden, John

    2011-04-15

    The hydroxyl radical (HO(•)) is a strong oxidant that reacts with electron-rich sites on organic compounds and initiates complex radical chain reactions in aqueous phase advanced oxidation processes (AOPs). Computer based kinetic modeling requires a reaction pathway generator and predictions of associated reaction rate constants. Previously, we reported a reaction pathway generator that can enumerate the most important elementary reactions for aliphatic compounds. For the reaction rate constant predictor, we develop linear free energy relationships (LFERs) between aqueous phase literature-reported HO(•) reaction rate constants and theoretically calculated free energies of activation for H-atom abstraction from a C-H bond and HO(•) addition to alkenes. The theoretical method uses ab initio quantum mechanical calculations, Gaussian 1-3, for gas phase reactions and a solvation method, COSMO-RS theory, to estimate the impact of water. Theoretically calculated free energies of activation are found to be within approximately ±3 kcal/mol of experimental values. Considering errors that arise from quantum mechanical calculations and experiments, this should be within the acceptable errors. The established LFERs are used to predict the HO(•) reaction rate constants within a factor of 5 from the experimental values. This approach may be applied to other reaction mechanisms to establish a library of rate constant predictions for kinetic modeling of AOPs. PMID:21410278

  18. Evaluation of free hydroxyl radical scavenging activities of some Chinese herbs by capillary zone electrophoresis with amperometric detection.

    PubMed

    Li, Hui; Wang, Qingjiang

    2004-04-01

    Due to the severe damage caused by free hydroxyl radicals (OH.) to cells and tissues, there is much interest in finding and studying effective and non-toxic OH. scavengers, including traditional Chinese herbs. In this paper, the simple and highly-sensitive technique of capillary zone electrophoresis with amperometric detection (CZE-AD) was used to study the OH. scavenging activities of aqueous extracts from some traditional Chinese herbs. Salicylic acid (SAL) was used as an OH. trap, and the content of OH. could be determined by assaying their products, 2,3-dihydroxybenzoic acid (2,3-DHBA) and 2,5-dihydroxybenzoic acid (2,5-DHBA). The optimum conditions for CZE-AD for the determination of 2,3-DHBA and 2,5-DHBA were explored. The linearity ranges of 2,3-DHBA and 2,5-DHBA were 1.0 x10(-7) approximately 1.0 x10(-4) mol L(-1), and their detection limits were as low as 2 x 10(-8) mol L(-1), which were much better than the CE-UV method often used. The traditional Chinese herbs studied included Radix angelicae sinensis, Rhizoma coptidis, Ligustrum lucidum, Ligusticum wallichii, Radices glycyrrhizae and Semen plantaginis. The experiments showed that the aqueous extracts from all of the above traditional Chinese herds had free OH. scavenging activities, although to different degrees. PMID:14985912

  19. Supporting Student Research Group Activities.

    ERIC Educational Resources Information Center

    Lopatin, Dennis E.

    1993-01-01

    This discussion describes methods that foster a healthy Student Research Group (SRG) and permits it to fulfill its responsibility in the development of the student researcher. The model used in the discussion is that of the University of Michigan School of Dentistry SRG. (GLR)

  20. Role of surface hydroxyl groups in promoting room temperature CO sensing by Pd-modified nanocrystalline SnO 2

    NASA Astrophysics Data System (ADS)

    Marikutsa, Artem V.; Rumyantseva, Marina N.; Yashina, Lada V.; Gaskov, Alexander M.

    2010-10-01

    SnO 2/Pd nanocomposites were synthesized via sol-gel method followed by variable processing procedures. The materials are sensitive to CO gas in the concentration range 2-100 ppm at room operating temperature. It was shown that modification of nanocrystalline tin dioxide by Pd changes the temperature dependence of sensor response, decreasing the temperature of maximal signal. To understand the mechanism of room temperature CO sensitivity, a number of SnO 2/Pd materials were characterized by XRD, TEM, BET, XPS and TPR techniques. From the results of FTIR, impedance and sensing measurements under variable ambient conditions it was concluded that improvement in CO sensitivity for Pd-modified SnO 2 is due to alteration of CO oxidation pathway. The reaction of CO with surface OH-groups at room temperature was proposed, the latter being more reactive than oxygen species due to the possible chain character of the reactions. It was proposed that Pd additive may initiate chain processes at room temperature.

  1. Oxidation of primary hydroxyl groups in chitooligomer by a laccase-TEMPO system and physico-chemical characterisation of oxidation products.

    PubMed

    Pei, Jicheng; Yin, Yunbei; Shen, Zhenghui; Bu, Xin; Zhang, Fangdong

    2016-01-01

    The aim of this study was to investigate the oxidation of chitooligomer by a laccase-TEMPO system which had not previously been examined. Chitooligomer was treated with laccase and TEMPO in order to evaluate the potential of a laccase-TEMPO system to improve the moisture absorption, moisture retention, and antioxidant abilities of chitooligomer. Chitooligomer was prepared by degradation of high molecular weight chitosan with hydrogen peroxide followed by oxidation using a laccase-TEMPO system. (13)C NMR and carboxylate ion content detection results indicated that the laccase-TEMPO system could selectively oxidise the C6 hydroxyl group of the chitooligomer into carboxyl group; molecular weight distribution changes suggest that the structure of the oxidised product had changed and the molecular size and molecular weight decreased with the molecules in aqueous solution having a compact structure. Oxidation of chitooligomer by a laccase-TEMPO system resulted in a significant improvement in the moisture absorption, moisture retention and antioxidant abilities. The oxidised product has potential application values in the pharmaceutical and cosmetics industries.

  2. Synthesis, characterization and biological activity of hydroxyl-bisphosphonic analogs of bile acids.

    PubMed

    Bortolini, Olga; Fantin, Giancarlo; Fogagnolo, Marco; Rossetti, Stefano; Maiuolo, Loredana; Di Pompo, Gemma; Avnet, Sofia; Granchi, Donatella

    2012-06-01

    Bisphosphonates (BPs) are now the most widely used drugs for diseases associated with increased bone resorption, such as osteoporosis, and tumor bone diseases. A significant drawback of the BPs is their poor oral absorption that is enhanced by the presence of bile acid substituents in the bisphosphonate framework, with no toxic effects. A straightforward synthesis of bile acid-containing hydroxy-bisphosphonates and a full characterization of these pharmaceutically important molecules, including an evaluation of affinity and the mechanism of binding to hydroxyapatite, is presented. The biological activity of bile acid-containing bisphosphonate salts was determined using the neutral-red assay on the L929 cell line and primary cultures of osteoclasts. The bioactivity of the new compounds was found superior than bisphosphonates of established activity. PMID:22483634

  3. Role of hydroxyl group in the inhibitive action of benzoic acid toward corrosion of aluminum in nitric acid

    SciTech Connect

    Yadav, P.N.S.; Singh, A.K.; Wadhwani, R.

    1999-10-01

    Corrosion inhibition action of benzoic acid, p-hydroxy benzoic acid, 2-4-dihydroxy benzoic acid, and 3-4-5-trihydroxy benzoic acid toward aluminum alloy 3003 (UNS A93003) in 20% (wt%) nitric acid (HNO{sub 3}) using different concentrations of these compounds at 30 C, 40 C, and 50 C has been studied thoroughly. 3-4-5-trihydroxy benzoic acid (inhibition efficiency (IE): 30% and 72%) was the most effective inhibitor followed by 2-4-dihydroxy benzoic acid (IE: 22% to 62%) p-hydroxy benzoic acid (IE: 11% to 52%), and benzoic acid (IE: 2.5% to 15%). IE increased with concentration and its maximum value was observed at 0.5% concentration of all inhibitors used. The percentage of IE of the inhibitors decreased with an increase in temperature from 30 C to 50 C. Values of heat adsorption and activation energy were calculated from weight loss data, which came out in the range for the reaction occurring at the surface. The behavior of inhibitors studied deviated from the Langmuir isotherm. The IE of higher hydroxy species was improved when more hydroxy centers were added. Anodic and cathodic polarization curves were shifted toward lower current density regions in the presence of inhibitors. This revealed that they were mixed inhibitors.

  4. Cationic Copolymerization of 3,3-Bis(hydroxymethyl)oxetane and Glycidol: Biocompatible Hyperbranched Polyether Polyols with High Content of Primary Hydroxyl Groups.

    PubMed

    Christ, Eva-Maria; Hobernik, Dominika; Bros, Matthias; Wagner, Manfred; Frey, Holger

    2015-10-12

    The cationic ring-opening copolymerization of 3,3-bis(hydroxymethyl)oxetane (BHMO) with glycidol using different comonomer ratios (BHMO content from 25 to 90%) and BF3OEt2 as an initiator has been studied. Apparent molecular weights of the resulting hyperbranched polyether copolymers ranged from 1400 to 3300 g mol(-1) (PDI: 1.21-1.48; method: SEC, linear PEG standards). Incorporation of both comonomers is evidenced by MALDI-TOF mass spectroscopy. All hyperbranched polyether polyols with high content of primary hydroxyl groups portray good solubility in water, which correlates with an increasing content of glycerol units. Detailed NMR characterization was employed to elucidate the copolymer microstructures. Kinetic studies via FTIR demonstrated a weak gradient-type character of the copolymers. MTT assays of the copolymers (up to 100 μg mL(-1)) on HEK and fibroblast cell lines (3T3, L929, WEHI) as well as viability tests on the fibroblast cells were carried out to assess the biocompatibility of the materials, confirming excellent biocompatibility. Transfection efficiency characterization by flow cytometry and confocal laser microscopy demonstrated cellular uptake of the copolymers. Antiadhesive properties of the materials on surfaces were assessed by adhesion assays with fibroblast cells.

  5. Cationic Copolymerization of 3,3-Bis(hydroxymethyl)oxetane and Glycidol: Biocompatible Hyperbranched Polyether Polyols with High Content of Primary Hydroxyl Groups.

    PubMed

    Christ, Eva-Maria; Hobernik, Dominika; Bros, Matthias; Wagner, Manfred; Frey, Holger

    2015-10-12

    The cationic ring-opening copolymerization of 3,3-bis(hydroxymethyl)oxetane (BHMO) with glycidol using different comonomer ratios (BHMO content from 25 to 90%) and BF3OEt2 as an initiator has been studied. Apparent molecular weights of the resulting hyperbranched polyether copolymers ranged from 1400 to 3300 g mol(-1) (PDI: 1.21-1.48; method: SEC, linear PEG standards). Incorporation of both comonomers is evidenced by MALDI-TOF mass spectroscopy. All hyperbranched polyether polyols with high content of primary hydroxyl groups portray good solubility in water, which correlates with an increasing content of glycerol units. Detailed NMR characterization was employed to elucidate the copolymer microstructures. Kinetic studies via FTIR demonstrated a weak gradient-type character of the copolymers. MTT assays of the copolymers (up to 100 μg mL(-1)) on HEK and fibroblast cell lines (3T3, L929, WEHI) as well as viability tests on the fibroblast cells were carried out to assess the biocompatibility of the materials, confirming excellent biocompatibility. Transfection efficiency characterization by flow cytometry and confocal laser microscopy demonstrated cellular uptake of the copolymers. Antiadhesive properties of the materials on surfaces were assessed by adhesion assays with fibroblast cells. PMID:26355352

  6. Demonstration of 26-hydroxylation of C27-steroids in human skin fibroblasts, and a deficiency of this activity in cerebrotendinous xanthomatosis.

    PubMed Central

    Skrede, S; Björkhem, I; Kvittingen, E A; Buchmann, M S; Lie, S O; East, C; Grundy, S

    1986-01-01

    26-Hydroxylation of 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha-triol and other C27-steroids was demonstrated in cultured skin fibroblasts from healthy individuals. Activities in skin fibroblasts were approximately 5-10% of those previously found in human liver homogenates, and were inhibited by CO. The apparent Km was lowest for 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha-triol (1.3 mumol/liter) and highest for 5-cholestene-3 beta, 7 alpha-diol (12 mumol/liter). The rate of 26-hydroxylation was highest with 7 alpha-hydroxy-4-cholesten-3-one. These characteristics are similar to those of hepatic mitochondrial C27-steroid 26-hydroxylase. In skin fibroblasts from three patients with cerebrotendinous xanthomatosis (CTX), 26-hydroxylation of C27-steroids proceeded at a rate of only 0.2-2.5% of healthy controls. No accumulation of endogenous 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha-triol could be demonstrated in these cells, and the lowered formation of radioactive, 26-hydroxylated products could not be explained by dilution of the labeled exogenous substrate. The present results add strong evidence to the concept that the primary metabolic defect in CTX is a deficiency of C27-steroid 26-hydroxylase. PMID:3745434

  7. Hydroxylated polybrominated diphenyl ethers exhibit different activities on thyroid hormone receptors depending on their degree of bromination

    SciTech Connect

    Ren, Xiao-Min Guo, Liang-Hong Gao, Yu Zhang, Bin-Tian Wan, Bin

    2013-05-01

    Polybrominated diphenyl ethers (PBDEs) have been shown to disrupt thyroid hormone (TH) functions in experimental animals, and one of the proposed disruption mechanisms is direct binding of hydroxylated PBDE (OH-PBDE) to TH receptors (TRs). However, previous data on TH receptor binding and TH activity of OH-PBDEs were very limited and sometimes inconsistent. In the present paper, we examined the binding potency of ten OH-PBDEs with different degrees of bromination to TR using a fluorescence competitive binding assay. The results showed that the ten OH-PBDEs bound to TR with potency that correlated to their bromination level. We further examined their effect on TR using a coactivator binding assay and GH3 cell proliferation assay. Different TR activities of OH-PBDEs were observed depending on their degree of bromination. Four low-brominated OH-PBDEs (2′-OH-BDE-28, 3′-OH-BDE-28, 5-OH-BDE-47, 6-OH-BDE-47) were found to be TR agonists, which recruited the coactivator peptide and enhanced GH3 cell proliferation. However, three high-brominated OH-PBDEs (3-OH-BDE-100, 3′-OH-BDE-154, 4-OH-BDE-188) were tested to be antagonists. Molecular docking was employed to simulate the interactions of OH-PBDEs with TR and identify the structural determinants for TR binding and activity. According to the docking results, low-brominated OH-PBDEs, which are weak binders but TR agonists, bind with TR at the inner side of its binding pocket, whereas high-brominated compounds, which are potent binders but TR antagonists, reside at the outer region. These results indicate that OH-PBDEs have different activities on TR (agonistic or antagonistic), possibly due to their different binding geometries with the receptor. - Highlights: ► Thyroid hormone (TH) activity of OH-PBDEs with different Br number was evaluated. ► Four different experimental approaches were employed to investigate the mechanism. ► Low-brominated OH-PBDEs were agonists, but high-brominated ones were antagonists.

  8. Antioxidant activity of trans-resveratrol toward hydroxyl and hydroperoxyl radicals: a quantum chemical and computational kinetics study.

    PubMed

    Iuga, Cristina; Alvarez-Idaboy, J Raúl; Russo, Nino

    2012-04-20

    In this work, we have carried out a systematic study of the antioxidant activity of trans-resveratrol toward hydroxyl ((•)OH) and hydroperoxyl ((•)OOH) radicals in aqueous simulated media using density functional quantum chemistry and computational kinetics methods. All possible mechanisms have been considered: hydrogen atom transfer (HAT), proton-coupled electron transfer (PCET), sequential electron proton transfer (SEPT), and radical adduct formation (RAF). Rate constants have been calculated using conventional transition state theory in conjunction with the Collins-Kimball theory. Branching ratios for the different paths contributing to the overall reaction, at 298 K, are reported. For the global reactivity of trans-resveratrol toward (•)OH radicals, in water at physiological pH, the main mechanism of reaction is proposed to be the sequential electron proton transfer (SEPT). However, we show that trans-resveratrol always reacts with (•)OH radicals at a rate that is diffusion-controlled, independent of the reaction pathway. This explains why trans-resveratrol is an excellent but very unselective (•)OH radical scavenger that provides antioxidant protection to the cell. Reaction between trans-resveratrol and the hydroperoxyl radical occurs only by phenolic hydrogen abstraction. The total rate coefficient is predicted to be 1.42 × 10(5) M(-1) s(-1), which is much smaller than the ones for reactions of trans-resveratrol with (•)OH radicals, but still important. Since the (•)OOH half-life time is several orders larger than the one of the (•)OH radical, it should contribute significantly to trans-resveratrol oxidation in aqueous biological media. Thus, trans-resveratrol may act as an efficient (•)OOH, and also presumably (•)OOR, radical scavenger. PMID:22475027

  9. Rate Constants and Activation Energies for Gas‐Phase Reactions of Three Cyclic Volatile Methyl Siloxanes with the Hydroxyl Radical

    PubMed Central

    Safron, Andreas; Strandell, Michael; Kierkegaard, Amelie

    2015-01-01

    ABSTRACT Reaction with hydroxyl radicals (OH) is the major pathway for removal of cyclic volatile methyl siloxanes (cVMS) from air. We present new measurements of second‐order rate constants for reactions of the cVMS octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) with OH determined at temperatures between 313 and 353 K. Our measurements were made using the method of relative rates with cyclohexane as a reference substance and were conducted in a 140‐mL gas‐phase reaction chamber with online mass spectrometry analysis. When extrapolated to 298 K, our measured reaction rate constants of D4 and D5 with the OH radical are 1.9 × 10−12 (95% confidence interval (CI): (1.7–2.2) × 10−12) and 2.6 × 10−12 (CI: (2.3–2.9) × 10−12) cm3 molecule−1 s−1, respectively, which are 1.9× and 1.7× faster than previous measurements. Our measured rate constant for D6 is 2.8 × 10−12 (CI: (2.5–3.2) × 10−12) cm3 molecule−1 s−1 and to our knowledge there are no comparable laboratory measurements in the literature. Reaction rates for D5 were 33% higher than for D4 (CI: 30–37%), whereas the rates for D6 were only 8% higher than for D5 (CI: 5–10%). The activation energies of the reactions of D4, D5, and D6 with OH were not statistically different and had a value of 4300 ± 2800 J/mol.

  10. Selective hydroxylation of alkanes by an extracellular fungal peroxygenase.

    PubMed

    Peter, Sebastian; Kinne, Matthias; Wang, Xiaoshi; Ullrich, René; Kayser, Gernot; Groves, John T; Hofrichter, Martin

    2011-10-01

    Fungal peroxygenases are novel extracellular heme-thiolate biocatalysts that are capable of catalyzing the selective monooxygenation of diverse organic compounds, using only H(2)O(2) as a cosubstrate. Little is known about the physiological role or the catalytic mechanism of these enzymes. We have found that the peroxygenase secreted by Agrocybe aegerita catalyzes the H(2)O(2)-dependent hydroxylation of linear alkanes at the 2-position and 3-position with high efficiency, as well as the regioselective monooxygenation of branched and cyclic alkanes. Experiments with n-heptane and n-octane showed that the hydroxylation proceeded with complete stereoselectivity for the (R)-enantiomer of the corresponding 3-alcohol. Investigations with a number of model substrates provided information about the route of alkane hydroxylation: (a) the hydroxylation of cyclohexane mediated by H(2)(18)(2) resulted in complete incorporation of (18)O into the hydroxyl group of the product cyclohexanol; (b) the hydroxylation of n-hexane-1,1,1,2,2,3,3-D(7) showed a large intramolecular deuterium isotope effect [(k(H)/k(D))(obs)] of 16.0 ± 1.0 for 2-hexanol and 8.9 ± 0.9 for 3-hexanol; and (c) the hydroxylation of the radical clock norcarane led to an estimated radical lifetime of 9.4 ps and an oxygen rebound rate of 1.06 × 10(11) s(-1). These results point to a hydrogen abstraction and oxygen rebound mechanism for alkane hydroxylation. The peroxygenase appeared to lack activity on long-chain alkanes (> C(16)) and highly branched alkanes (e.g. tetramethylpentane), but otherwise exhibited a broad substrate range. It may accordingly have a role in the bioconversion of natural and anthropogenic alkane-containing structures (including alkyl chains of complex biomaterials) in soils, plant litter, and wood. PMID:21812933

  11. Novel hydroxyl radical scavenging antioxidant activity assay for water-soluble antioxidants using a modified CUPRAC method.

    PubMed

    Bektaşoğlu, Burcu; Esin Celik, Saliha; Ozyürek, Mustafa; Güçlü, Kubilay; Apak, Reşat

    2006-07-01

    Reactive oxygen species (ROS) such as superoxide anion, hydroxyl ((*)OH), peroxyl, and alkoxyl radicals may attack biological macromolecules giving rise to oxidative stress-originated diseases. Since (*)OH is very short-lived, secondary products resulting from (*)OH attack to various probes are measured. Although the measurement of aromatic hydroxylation with HPLC/electrochemical detection is more specific than the low-yield TBARS test, it requires sophisticated instrumentation. As a more convenient and less costly alternative, we used p-aminobenzoate, 2,4- and 3,5-dimethoxybenzoate probes for detecting hydroxyl radicals generated from an equivalent mixture of Fe(II)+EDTA with hydrogen peroxide. The produced hydroxyl radicals attacked both the probe and the water-soluble antioxidants in 37 degrees C-incubated solutions for 2h. The CUPRAC (i.e., our original method for total antioxidant capacity assay) absorbance of the ethylacetate extract due to the reduction of Cu(II)-neocuproine reagent by the hydroxylated probe decreased in the presence of (*)OH scavengers, the difference being proportional to the scavenging ability of the tested compound. A rate constant for the reaction of the scavenger with hydroxyl radical can be deduced from the inhibition of color formation. The second-order rate constants of the scavengers were determined with competition kinetics by means of a linear plot of A(0)/A as a function of C(scavenger)/C(probe), where A(0) and A are the CUPRAC absorbances of the system in the absence and presence of scavenger, respectively, and C is the molar concentration of relevant species. The 2,4- and 3,5-dimethoxybenzoates were the best probes in terms of linearity and sensitivity. Iodide, metabisulfite, hexacyanoferrate(II), thiourea, formate, and dimethyl sulfoxide were shown by the modified CUPRAC assay to be more effective scavengers than mannitol, glucose, lysine, and simple alcohols, as in the TBARS assay. The developed method is less lengthy, more

  12. Antrodia camphorata Potentiates Neuroprotection against Cerebral Ischemia in Rats via Downregulation of iNOS/HO-1/Bax and Activated Caspase-3 and Inhibition of Hydroxyl Radical Formation.

    PubMed

    Yang, Po-Sheng; Lin, Po-Yen; Chang, Chao-Chien; Yu, Meng-Che; Yen, Ting-Lin; Lan, Chang-Chou; Jayakumar, Thanasekaran; Yang, Chih-Hao

    2015-01-01

    Antrodia camphorata (A. camphorata) is a fungus generally used in Chinese folk medicine for treatment of viral hepatitis and cancer. Our previous study found A. camphorata has neuroprotective properties and could reduce stroke injury in cerebral ischemia animal models. In this study, we sought to investigate the molecular mechanisms of neuroprotective effects of A. camphorata in middle cerebral artery occlusion (MCAO) rats. A selective occlusion of the middle cerebral artery (MCA) with whole blood clots was used to induce ischemic stroke in rats and they were orally treated with A. camphorata (0.25 and 0.75 g/kg/day) alone or combined with aspirin (5 mg/kg/day). To provide insight into the functions of A. camphorata mediated neuroprotection, the expression of Bax, inducible nitric oxide synthase (iNOS), haem oxygenase-1 (HO-1), and activated caspase-3 was determined by Western blot assay. Treatment of aspirin alone significantly reduced the expressions of HO-1 (P < 0.001), iNOS (P < 0.001), and Bax (P < 0.01) in ischemic regions. The reduction of these expressions was more potentiated when rats treated by aspirin combined with A. camphorata (0.75 g/kg/day). Combination treatment also reduced apoptosis as measured by a significant reduction in active caspase-3 expression in the ischemic brain compared to MCAO group (P < 0.01). Moreover, treatment of A. camphorata significantly (P < 0.05) reduced fenton reaction-induced hydroxyl radical (OH(•)) formation at a dose of 40 mg/mL. Taken together, A. camphorata has shown neuroprotective effects in embolic rats, and the molecular mechanisms may correlate with the downregulation of Bax, iNOS, HO-1, and activated caspase-3 and the inhibition of OH(•) signals.

  13. Antrodia camphorata Potentiates Neuroprotection against Cerebral Ischemia in Rats via Downregulation of iNOS/HO-1/Bax and Activated Caspase-3 and Inhibition of Hydroxyl Radical Formation

    PubMed Central

    Yang, Po-Sheng; Lin, Po-Yen; Chang, Chao-Chien; Yu, Meng-Che; Yen, Ting-Lin; Lan, Chang-Chou; Jayakumar, Thanasekaran; Yang, Chih-Hao

    2015-01-01

    Antrodia camphorata (A. camphorata) is a fungus generally used in Chinese folk medicine for treatment of viral hepatitis and cancer. Our previous study found A. camphorata has neuroprotective properties and could reduce stroke injury in cerebral ischemia animal models. In this study, we sought to investigate the molecular mechanisms of neuroprotective effects of A. camphorata in middle cerebral artery occlusion (MCAO) rats. A selective occlusion of the middle cerebral artery (MCA) with whole blood clots was used to induce ischemic stroke in rats and they were orally treated with A. camphorata (0.25 and 0.75 g/kg/day) alone or combined with aspirin (5 mg/kg/day). To provide insight into the functions of A. camphorata mediated neuroprotection, the expression of Bax, inducible nitric oxide synthase (iNOS), haem oxygenase-1 (HO-1), and activated caspase-3 was determined by Western blot assay. Treatment of aspirin alone significantly reduced the expressions of HO-1 (P < 0.001), iNOS (P < 0.001), and Bax (P < 0.01) in ischemic regions. The reduction of these expressions was more potentiated when rats treated by aspirin combined with A. camphorata (0.75 g/kg/day). Combination treatment also reduced apoptosis as measured by a significant reduction in active caspase-3 expression in the ischemic brain compared to MCAO group (P < 0.01). Moreover, treatment of A. camphorata significantly (P < 0.05) reduced fenton reaction-induced hydroxyl radical (OH•) formation at a dose of 40 mg/mL. Taken together, A. camphorata has shown neuroprotective effects in embolic rats, and the molecular mechanisms may correlate with the downregulation of Bax, iNOS, HO-1, and activated caspase-3 and the inhibition of OH• signals. PMID:26379739

  14. Influence of hydroxyl substitution on flavanone antioxidants properties.

    PubMed

    Masek, Anna; Chrzescijanska, Ewa; Latos, Malgorzata; Zaborski, Marian

    2017-01-15

    The aim of our study was to determine the effect of the position of the hydroxyl group on the antioxidant properties of flavonoid derivatives. For this purpose, we performed electrochemical analysis and quantum-mechanical calculations to describe the mechanisms of electrochemical oxidation, and we selected the two methods of ABTS (2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) and DPPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate), which allowed us to determine the ability to scavenge free radicals. On the basis of the research, we found that the derivatives of flavonoids, which have a hydroxyl group substituted at the R-3 position on the C ring, have outstanding antioxidant activity. Flavone, which had an OH group substituted at the R-6 and R-7 position on the ring A, showed similar antioxidant activity to flavone without -OH groups in the structure and slightly higher activity than the di-substituted flavone on the ring A. PMID:27542504

  15. Hyperbranched Aliphatic Polyester Modified Activated Carbon Particles with Homogenized Surface Groups

    NASA Astrophysics Data System (ADS)

    Liu, Peng; Zhang, Liuxue

    The hyperbranched aliphatic polyester grafted activated carbon (HAPE-AC), was successfully prepared by the simple "one-pot" method. The surface functional groups of commercial activated carbon particles were homogenized to hydroxyl groups by being oxidized with nitric acid and then reduced with lithium tetrahydroaluminate (LiAlH4) at first. Secondly, the surface hydroxyl groups were used as the active sites for the solution polycondensation of the AB2 monomer, 2, 2-bis(hydroxymethyl)propionic acid (bis-MPA), with the catalysis of p-toluenesulfonic acid (p-TSA). The homogenization of the surface groups of the activated carbon particles and the graft polymerization of the hyperbranched aliphatic polyester were investigated by X-ray photoelectron spectroscopy (XPS) technique. The products were also characterized with Fourier transform infrared (FT-IR) and scanning electron microscope (SEM). The competitive adsorption properties of the products toward the heavy metal ions (Cu(II), Hg(II), Zn(II), and Cd(II)) also proved the translations of the surface groups.

  16. Hydroxyl radical scavenging reactivity of proton pump inhibitors.

    PubMed

    Simon, Wolfgang Alexander; Sturm, Ernst; Hartmann, Hans-Jürgen; Weser, Ulrich

    2006-04-28

    In addition to the established control of acid secretion of the class of proton pump inhibitors (PPI) reactivity from the pyridyl methyl sulphinyl benzimidazole type a second independent anti-inflammatory reactivity was observed in vitro. This inhibitory reactivity was clearly noticed using three different assays where the aggressive hydroxyl radicals were successfully trapped in a concentration dependent manner. There is unequivocal evidence that the proton pump inhibitors having the sulphoxide group are able to scavenge hydroxyl radicals which are generated during a Fenton reaction. By way of contrast, the corresponding thioethers were substantially less active. No detectable effect was seen in the superoxide radical scavenging system. In conclusion, pantoprazole as well as the other proton pump inhibitors have a pronounced inhibitory reactivity towards hydroxyl radicals.

  17. Water concentrations and hydrogen isotope compositions of alkaline basalt-hosted clinopyroxene megacrysts and amphibole clinopyroxenites: the role of structural hydroxyl groups and molecular water

    NASA Astrophysics Data System (ADS)

    Kovács, István; Demény, Attila; Czuppon, György; Lécuyer, Christophe; Fourel, Francois; Xia, Qun-Ke; Liu, Jia; Pintér, Zsanett; Király, Edit; Török, Kálmán; Szabó, Ábel; Deloule, Etienne; Falus, György; Fancsik, Tamás; Zajacz, Zoltán; Sándorné Kovács, Judit; Udvardi, Beatrix

    2016-05-01

    The aim of this study was to determine both `water' contents (as OH- and H2O) and δD values of several clinopyroxene samples from alkaline basalts. These parameters were first obtained from five clinopyroxene samples using both the classical `off-line' vacuum extraction technique and the `on-line' high-temperature pyrolysis technique. Blanks measured with the `on-line' gas extraction techniques were low enough to prevent any contamination by atmospheric water vapour. The comparison of data has revealed that our `on-line' procedure is more effective for the extraction of `water' from clinopyroxenes and, consequently, this `on-line' technique was applied to ten additional clinopyroxene samples. Sample δD values cover a similar range from -95 to -45 ‰ (VSMOW) regardless of the studied locations, whereas the total `water' content varies from ~115 to ~2570 ppm. The structural hydroxyl content of clinopyroxene samples measured by micro-FTIR spectrometry varies from ~0 to 476 ppm expressed in molecular water equivalent. The total `water' concentrations determined by mass spectrometry differ considerably from structural hydroxyl contents constrained by micro-FTIR, thus indicating that considerable proportion of the `water' may be present in (nano)-inclusions. The structural hydroxyl concentration—apart from clinopyroxenes separated from amphibole clinopyroxenite xenoliths—correlates positively with the δD values of clinopyroxene megacrysts for each locality, indicating that structurally bond hydrogen in clinopyroxenes may have δD values higher than molecular water in inclusions. This implies that there may be a significant hydrogen isotope fractionation for structural hydroxyl during crystallization of clinopyroxene, while for molecular water there may be no or only negligible isotope fractionation.

  18. A novel Pd3O9@α-Al2O3 catalyst under a hydroxylated effect: high activity in the CO oxidation reaction.

    PubMed

    Li, Qiaohong; Wei, Yongqin; Sa, Rongjian; Ma, Zuju; Wu, Kechen

    2015-12-28

    Considering the importance of palladium-based and doped metal-oxide catalysts in CO oxidation, we design a new Pd3O9@α-Al2O3 catalyst and simulate its efficiency under a hydroxylated effect. The structure, electronic structure and oxidation activity of the hydroxylated Pd3O9@α-Al2O3(0001) surface are investigated by density functional theory. Under the O-rich growth conditions, Pd preferentially replaces Al. The lowest formation energy of the Pd-doped α-Al2O3(0001) surface is 0.21 eV under conditions wherein the coverage of the Pd-doped α-Al2O3 is 0.75 on a pre-hydroxylated surface and the water coverage is 0.25, which leads to formation of a Pd3O9 cluster embedded in the Al2O3(0001) surface. The reaction mechanisms of CO oxidization have been elucidated first by CO adsorption and migration, second by O(v) formation with the first CO2 release, then by the first foreign O2 filling and CO co-adsorption, and finally by the second CO2 desorption and restoration of the hydroxylated Pd3O9@α-Al2O3(0001) surface. The rate-determining step is the formation of the first CO2 in the whole catalytic cycle. The results also indicate that the energy barrier for CO oxidization is obviously reduced compared to that of the undoped surface, which implies that the introduction of Pd can efficiently improve the oxidation reactivity of the α-Al2O3(0001) surface. Compared to the synthesized Ir1/FeO(x) (1.41 eV) and Pt1/FeO(x) (0.79 eV) catalysts, the reaction activation barrier of CO oxidation is lowered by 0.65 eV and 0.03 eV, respectively. Therefore, the Pd3O9@α-Al2O3 catalyst shows superior catalytic activity in CO oxidation. The present results enrich the understanding of the catalytic oxidation of CO by palladium-based catalysts and provide a clue for fabricating palladium-based catalysts with low cost and high activity.

  19. A novel Pd3O9@α-Al2O3 catalyst under a hydroxylated effect: high activity in the CO oxidation reaction.

    PubMed

    Li, Qiaohong; Wei, Yongqin; Sa, Rongjian; Ma, Zuju; Wu, Kechen

    2015-12-28

    Considering the importance of palladium-based and doped metal-oxide catalysts in CO oxidation, we design a new Pd3O9@α-Al2O3 catalyst and simulate its efficiency under a hydroxylated effect. The structure, electronic structure and oxidation activity of the hydroxylated Pd3O9@α-Al2O3(0001) surface are investigated by density functional theory. Under the O-rich growth conditions, Pd preferentially replaces Al. The lowest formation energy of the Pd-doped α-Al2O3(0001) surface is 0.21 eV under conditions wherein the coverage of the Pd-doped α-Al2O3 is 0.75 on a pre-hydroxylated surface and the water coverage is 0.25, which leads to formation of a Pd3O9 cluster embedded in the Al2O3(0001) surface. The reaction mechanisms of CO oxidization have been elucidated first by CO adsorption and migration, second by O(v) formation with the first CO2 release, then by the first foreign O2 filling and CO co-adsorption, and finally by the second CO2 desorption and restoration of the hydroxylated Pd3O9@α-Al2O3(0001) surface. The rate-determining step is the formation of the first CO2 in the whole catalytic cycle. The results also indicate that the energy barrier for CO oxidization is obviously reduced compared to that of the undoped surface, which implies that the introduction of Pd can efficiently improve the oxidation reactivity of the α-Al2O3(0001) surface. Compared to the synthesized Ir1/FeO(x) (1.41 eV) and Pt1/FeO(x) (0.79 eV) catalysts, the reaction activation barrier of CO oxidation is lowered by 0.65 eV and 0.03 eV, respectively. Therefore, the Pd3O9@α-Al2O3 catalyst shows superior catalytic activity in CO oxidation. The present results enrich the understanding of the catalytic oxidation of CO by palladium-based catalysts and provide a clue for fabricating palladium-based catalysts with low cost and high activity. PMID:26308732

  20. 3D QSAR studies of hydroxylated polychlorinated biphenyls as potential xenoestrogens.

    PubMed

    Ruiz, Patricia; Ingale, Kundan; Wheeler, John S; Mumtaz, Moiz

    2016-02-01

    Mono-hydroxylated polychlorinated biphenyls (OH-PCBs) are found in human biological samples and lack of data on their potential estrogenic activity has been a source of concern. We have extended our previous in silico 2D QSAR study through the application of advance techniques such as docking and 3D QSAR to gain insights into their estrogen receptor (ERα) binding. The results support our earlier findings that the hydroxyl group is the most important feature on the compounds; its position, orientation and surroundings in the structure are influential for the binding of OH-PCBs to ERα. This study has also revealed the following additional interactions that influence estrogenicity of these chemicals (a) the aromatic interactions of the biphenyl moieties with the receptor, (b) hydrogen bonding interactions of the p-hydroxyl group with key amino acids ARG394 and GLU353, (c) low or no electronegative substitution at para-positions of the p-hydroxyl group, (d) enhanced electrostatic interactions at the meta position on the B ring, and (e) co-planarity of the hydroxyl group on the A ring. In combination the 2D and 3D QSAR approaches have led us to the support conclusion that the hydroxyl group is the most important feature on the OH-PCB influencing the binding to estrogen receptors, and have enhanced our understanding of the mechanistic details of estrogenicity of this class of chemicals. Such in silico computational methods could serve as useful tools in risk assessment of chemicals. PMID:26598992

  1. Chiral Hydroxylation at the Mononuclear Nonheme Fe(II) Center of 4-(S) Hydroxymandelate Synthase – A Structure-Activity Relationship Analysis

    PubMed Central

    Di Giuro, Cristiana M. L.; Konstantinovics, Cornelia; Rinner, Uwe; Nowikow, Christina; Leitner, Erich; Straganz, Grit D.

    2013-01-01

    (S)-Hydroxymandelate synthase (Hms) is a nonheme Fe(II) dependent dioxygenase that catalyzes the oxidation of 4-hydroxyphenylpyruvate to (S)-4-hydroxymandelate by molecular oxygen. In this work, the substrate promiscuity of Hms is characterized in order to assess its potential for the biosynthesis of chiral α-hydroxy acids. Enzyme kinetic analyses, the characterization of product spectra, quantitative structure activity relationship (QSAR) analyses and in silico docking studies are used to characterize the impact of substrate properties on particular steps of catalysis. Hms is found to accept a range of α-oxo acids, whereby the presence of an aromatic substituent is crucial for efficient substrate turnover. A hydrophobic substrate binding pocket is identified as the likely determinant of substrate specificity. Upon introduction of a steric barrier, which is suspected to obstruct the accommodation of the aromatic ring in the hydrophobic pocket during the final hydroxylation step, the racemization of product is obtained. A steady state kinetic analysis reveals that the turnover number of Hms strongly correlates with substrate hydrophobicity. The analysis of product spectra demonstrates high regioselectivity of oxygenation and a strong coupling efficiency of C-C bond cleavage and subsequent hydroxylation for the tested substrates. Based on these findings the structural basis of enantioselectivity and enzymatic activity is discussed. PMID:23935907

  2. A series of hybrid P450 BM3 enzymes with different catalytic activity in the light-initiated hydroxylation of lauric acid

    PubMed Central

    Tran, Ngoc-Han; Huynh, Ngoc; Chavez, Garrett; Nguyen, Angelina; Dwaraknath, Sudharsan; Nguyen, Thien-Anh; Nguyen, Maxine; Cheruzel, Lionel

    2012-01-01

    We have developed a series of hybrid P450 BM3 enzymes to perform the light-activated hydroxylation of lauric acid. These enzymes contain a Ru(II)-diimine photosensitizer covalently attached to single cysteine residues of mutant P450 BM3 heme domains. The library of hybrid enzymes includes four non-native single cysteine mutants (K97C, Q397C, Q109C and L407C). In addition, mutations around the heme active site, F87A and I401P, were inserted in the Q397C mutant. Two heteroleptic Ru(II) complexes, Ru(bpy)2phenA (1) and Ru(phen)2phenA (2) (bpy=bipyridine, phen=1,10-phenanthroline, and phenA=5-acetamido-1,10-phenanthroline), are used as photosensitizers. Upon visible light irradiation, the hybrid enzymes display various total turnover numbers in the hydroxylation of lauric acid, up to 140 for the L407C-1 mutant, a 16-fold increase compared to the F87A/Q397C-1 mutant. CO binding studies confirm the ability of the photogenerated Ru(I) compound to reduce the fraction of ferric high spin species present in the mutants upon substrate binding. PMID:22922311

  3. Hydroxylation activity of P450 BM-3 mutant F87V towards aromatic compounds and its application to the synthesis of hydroquinone derivatives from phenolic compounds.

    PubMed

    Sulistyaningdyah, Woro Triarsi; Ogawa, Jun; Li, Qing-Shan; Maeda, Chiharu; Yano, Yuki; Schmid, Rolf D; Shimizu, Sakayu

    2005-06-01

    Cytochrome P450 BM-3 from Bacillus megaterium is a fatty acid hydroxylase exhibiting selectivity for long-chain substrates (12-20 carbons). Replacement of Phe87 in P450 BM-3 by Val (F87V) greatly increased its activity towards a variety of aromatic and phenolic compounds. The apparent initial reaction rates of F87V as to benzothiophene, indan, 2,6-dichlorophenol, and 2-(benzyloxy)phenol were 227, 204, 129, and 385 nmol min(-1) nmol(-1) P450, which are 220-, 66-, 99-, and 963-fold those of the wild type, respectively. These results indicate that Phe87 plays a critical role in the control of the substrate specificity of P450 BM-3. Furthermore, F87V catalyzed regioselective hydroxylation at the para position of various phenolic compounds. In particular, F87V showed high activity as to the hydroxylation of 2-(benzyloxy)phenol to 2-(benzyloxy)hydroquinone. With F87V as the catalyst, 0.71 mg ml(-1) 2-(benzyloxy)hydroquinone was produced from 1.0 mg ml(-1) 2-(benzyloxy)phenol in 4 h, with a molar yield of 66%.

  4. Advanced Extravehicular Activity Breakout Group Summary

    NASA Technical Reports Server (NTRS)

    Kosmo, Joseph J.; Perka, Alan; Walz, Carl; Cobb, Sharon; Hanford, Anthony; Eppler, Dean

    2005-01-01

    This viewgraph document summarizes the workings of the Advanced Extravehicular Activity (AEVA) Breakout group in a Martian environment. The group was tasked with: identifying potential contaminants and pathways for AEVA systems with respect to forward and backward contamination; identifying plausible mitigation alternatives and obstacles for pertinent missions; identifying topics that require further research and technology development and discuss development strategies with uncertain Planetary Protection (PP) requirements; Identifying PP requirements that impose the greatest mission/development costs; Identifying PP requirements/topics that require further definition;

  5. Phytanic acid oxidation: normal activation and transport yet defective alpha-hydroxylation of phytanic acid in peroxisomes from Refsum disease and rhizomelic chondrodysplasia punctata.

    PubMed

    Pahan, K; Khan, M; Singh, I

    1996-05-01

    In humans the oxidation of phytanic acid is a peroxisomal function. To understand the possible mechanisms for the pathognomic accumulation of phytanic acid in plasma and body fluids of Refsum disease (RD) and rhizomelic chondrodysplasia punctata (RCDP), we investigated activities of various steps (activation, transport, and oxidation) in the metabolism of phytanic acid in peroxisomes isolated from cultured skin fibroblasts from control, RD, and RCDP subjects. Activation of phytanic acid was normal in peroxisomes from both RD and RCDP. Transport of phytanic acid or phytanoyl-CoA in the absence or presence of fatty acid activating cofactors (ATP, MgCl2, and CoASH) into peroxisomes isolated from RD and RCDP skin fibroblasts was also similar to that of peroxisomes from control fibroblasts. Defective oxidation of [(2,3)-3H]- or [1-14C]phytanic acid, or [1-14C]phytanoyl-CoA (substrate for the first step of alpha-oxidation) but normal oxidation of [1-14C] alpha-hydroxyphytanic acid (substrate for the second step of the alpha-oxidation pathway) in peroxisomes from RD clearly demonstrates that excessive accumulation of phytanic acid in plasma and body fluids of RD is due to the deficiency of phytanic acid alpha-hydroxylase in peroxisomes. However, in RCDP peroxisomes, in addition to deficient oxidation of [1-14C]phytanic acid or phytanoyl-CoA or [(2,3)-3H]phytanic acid, the oxidation of [1-14C] alpha-hydroxyphytanic acid was also deficient, indicating that in RCDP the activities both of alpha-hydroxylation of phytanic acid and decarboxylation of alpha-hydroxyphytanic acid are deficient. These observations indicate that peroxisomal membrane functions (phytanic acid activation and transport) in phytanic acid metabolism are normal in both RD and RCDP. The defect in RD is in the alpha-hydroxylation of phytanic acid; whereas in RCDP both alpha-hydroxylation of phytanic acid as well as decarboxylation of alpha-hydroxyphytanic acid are deficient.

  6. The radiocarbon hydroxyl technique

    NASA Technical Reports Server (NTRS)

    Campbell, Malcolm J.; Sheppard, John C.

    1994-01-01

    The Radiocarbon Technique depends upon measuring the rate of oxidation of CO in an essentially unperturbed sample of air. The airborne technique is slightly different. Hydroxyl concentrations can be calculated directly; peroxyl concentrations can be obtained by NO doping.

  7. Structural evidence for enhancement of sequential vitamin D3 hydroxylation activities by directed evolution of cytochrome P450 vitamin D3 hydroxylase.

    PubMed

    Yasutake, Yoshiaki; Fujii, Yoshikazu; Nishioka, Taiki; Cheon, Woo-Kwang; Arisawa, Akira; Tamura, Tomohiro

    2010-10-01

    Vitamin D(3) hydroxylase (Vdh) isolated from actinomycete Pseudonocardia autotrophica is a cytochrome P450 (CYP) responsible for the biocatalytic conversion of vitamin D(3) (VD(3)) to 1α,25-dihydroxyvitamin D(3) (1α,25(OH)(2)VD(3)) by P. autotrophica. Although its biological function is unclear, Vdh is capable of catalyzing the two-step hydroxylation of VD(3), i.e. the conversion of VD(3) to 25-hydroxyvitamin D(3) (25(OH)VD(3)) and then of 25(OH)VD(3) to 1α,25(OH)(2)VD(3), a hormonal form of VD(3). Here we describe the crystal structures of wild-type Vdh (Vdh-WT) in the substrate-free form and of the highly active quadruple mutant (Vdh-K1) generated by directed evolution in the substrate-free, VD(3)-bound, and 25(OH)VD(3)-bound forms. Vdh-WT exhibits an open conformation with the distal heme pocket exposed to the solvent both in the presence and absence of a substrate, whereas Vdh-K1 exhibits a closed conformation in both the substrate-free and substrate-bound forms. The results suggest that the conformational equilibrium was largely shifted toward the closed conformation by four amino acid substitutions scattered throughout the molecule. The substrate-bound structure of Vdh-K1 accommodates both VD(3) and 25(OH)VD(3) but in an anti-parallel orientation. The occurrence of the two secosteroid binding modes accounts for the regioselective sequential VD(3) hydroxylation activities. Moreover, these structures determined before and after directed evolution, together with biochemical and spectroscopic data, provide insights into how directed evolution has worked for significant enhancement of both the VD(3) 25-hydroxylase and 25(OH)VD(3) 1α-hydroxylase activities.

  8. CYP3A Specifically Catalyzes 1β-Hydroxylation of Deoxycholic Acid: Characterization and Enzymatic Synthesis of a Potential Novel Urinary Biomarker for CYP3A Activity.

    PubMed

    Hayes, Martin A; Li, Xue-Qing; Grönberg, Gunnar; Diczfalusy, Ulf; Andersson, Tommy B

    2016-09-01

    The endogenous bile acid metabolite 1β-hydroxy-deoxycholic acid (1β-OH-DCA) excreted in human urine may be used as a sensitive CYP3A biomarker in drug development reflecting in vivo CYP3A activity. An efficient and stereospecific enzymatic synthesis of 1β-OH-DCA was developed using a Bacillus megaterium (BM3) cytochrome P450 (P450) mutant, and its structure was confirmed by nuclear magnetic resonance (NMR) spectroscopy. A [(2)H4]-labeled analog of 1β-OH-DCA was also prepared. The major hydroxylated metabolite of deoxycholic acid (DCA) in human liver microsomal incubations was identified as 1β-OH-DCA by comparison with the synthesized reference analyzed by UPLC-HRMS. Its formation was strongly inhibited by CYP3A inhibitor ketoconazole. Screening of 21 recombinant human cytochrome P450 (P450) enzymes showed that, with the exception of extrahepatic CYP46A1, the most abundant liver P450 subfamily CYP3A, including CYP3A4, 3A5, and 3A7, specifically catalyzed 1β-OH-DCA formation. This indicated that 1β-hydroxylation of DCA may be a useful marker reaction for CYP3A activity in vitro. The metabolic pathways of DCA and 1β-OH-DCA in human hepatocytes were predominantly via glycine and, to a lesser extent, via taurine and sulfate conjugation. The potential utility of 1β-hydroxylation of DCA as a urinary CYP3A biomarker was illustrated by comparing the ratio of 1β-OH-DCA:DCA in a pooled spot urine sample from six healthy control subjects to a sample from one patient treated with carbamazepine, a potent CYP3A inducer; 1β-OH-DCA:DCA was considerably higher in the patient versus controls (ratio 2.8 vs. 0.4). Our results highlight the potential of 1β-OH-DCA as a urinary biomarker in clinical CYP3A DDI studies. PMID:27402728

  9. Catalytic selective etherification of hydroxyl groups in 5-hydroxymethylfurfural over H4SiW12O40/MCM-41 nanospheres for liquid fuel production.

    PubMed

    Che, Penghua; Lu, Fang; Zhang, Junjie; Huang, Yizheng; Nie, Xin; Gao, Jin; Xu, Jie

    2012-09-01

    5-Hydroxymethylfurfural (HMF) is an important biomass-derived building block, but production and sustainable utilization of HMF remain challenging due to reactions of the highly reactive functional groups of this compound. H(4)SiW(12)O(40)/MCM-41 nanospheres were developed that exhibit 84.1% selectivity to 5-ethoxymethylfurfural (EMF) when HMF conversion reaches 92.0%, during etherification of 5-hydroxymethylfurfural (HMF) with ethanol under mild conditions. The catalyst could be reused, and its activity remained unaffected over five cycles. The strong acidity of the catalyst significantly enhanced etherification. The acetalized byproducts, 5-(diethoxymethyl)-2-furanmethanol and the HMF-dimer (5,5'(oxy-bis(methylene))bis-2-furfural), can be converted into HMF and then transformed to the main product, EMF, by using this catalyst to shift the reaction equilibrium. PMID:22749371

  10. Hydroxyl radicals in indoor environments

    NASA Astrophysics Data System (ADS)

    Sarwar, Golam; Corsi, Richard; Kimura, Yosuke; Allen, David; Weschler, Charles J.

    Indoor hydroxyl radical concentrations were estimated using a new indoor air quality model which employs the SAPRC-99 atmospheric chemistry model to simulate indoor homogenous reactions. Model results indicate that typical indoor hydroxyl radical concentrations are lower than typical outdoor summertime urban hydroxyl radical levels of 5-10×10 6 molecules cm -3; however, indoor levels can be similar to or greater than typical nighttime outdoor hydroxyl radical levels of approximately 5×10 4 molecules cm -3. Effects of selected parameters on indoor hydroxyl radical concentrations are presented herein. Indoor hydroxyl radical concentrations are predicted to increase non-linearly with increasing outdoor ozone concentrations, indoor alkene emission rates, and air exchange rates. Indoor hydroxyl radical concentrations decrease with increasing outdoor nitric oxide concentrations. Indoor temperature and indoor light intensity have moderate impacts on indoor hydroxyl radical concentrations. Outdoor hydroxyl radical concentrations, outdoor nitrate (NO 3rad ) radical concentrations, outdoor hydroperoxy radical concentrations, and hydroxyl radical removal by indoor surfaces are predicted to have no appreciable impact on indoor hydroxyl radical concentrations. Production of hydroxyl radicals in indoor environments appears to be controlled primarily by reactions of alkenes with ozone, and nitric oxide with hydroperoxy radical. Estimated indoor hydroxyl radical levels may potentially affect indoor air quality. Two examples are presented in which reactions of d-limonene and α-pinene with indoor hydroxyl radicals produce aldehydes, which may be of greater concern than the original compounds.

  11. Intracellular proton-mediated activation of TRPV3 channels accounts for the exfoliation effect of α-hydroxyl acids on keratinocytes.

    PubMed

    Cao, Xu; Yang, Fan; Zheng, Jie; Wang, Kewei

    2012-07-27

    α-Hydroxyl acids (AHAs) from natural sources act as proton donors and topical compounds that penetrate skin and are well known in the cosmetic industry for their use in chemical peels and improvement of the skin. However, little is known about how AHAs cause exfoliation to expose fresh skin cells. Here we report that the transient receptor potential vanilloid 3 (TRPV3) channel in keratinocytes is potently activated by intracellular acidification induced by glycolic acid. Patch clamp recordings and cell death assay of both human keratinocyte HaCaT cells and TRPV3-expressing HEK-293 cells confirmed that intracellular acidification led to direct activation of TRPV3 and promoted cell death. Site-directed mutagenesis revealed that an N-terminal histidine residue, His-426, known to be involved in 2-aminoethyl diphenylborinate-mediated TRPV3 activation, is critical for sensing intracellular proton levels. Taken together, our findings suggest that intracellular protons can strongly activate TRPV3, and TRPV3-mediated proton sensing and cell death in keratinocytes may serve as a molecular basis for the cosmetic use of AHAs and their therapeutic potential in acidic pH-related skin disorders.

  12. Studies on the selectivity between nickel-catalyzed 1,2-cis-2-amino glycosylation of hydroxyl groups of thioglycoside acceptors with C2-substituted benzylidene N-phenyl trifluoroacetimidates and intermolecular aglycon transfer of the sulfide group.

    PubMed

    Yu, Fei; Nguyen, Hien M

    2012-09-01

    The stereoselective synthesis of saccharide thioglycosides containing 1,2-cis-2-amino glycosidic linkages is challenging. In addition to the difficulties associated with achieving high α-selectivity in the formation of 1,2-cis-2-amino glycosidic bonds, the glycosylation reaction is hampered by undesired transfer of the anomeric sulfide group from the glycosyl acceptor to the glycosyl donor. Overcoming these obstacles will pave the way for the preparation of oligosaccharides and glycoconjugates bearing the 1,2-cis-2-amino glycosidic linkages because the saccharide thioglycosides obtained can serve as donors for another coupling iteration. This approach streamlines selective deprotection and anomeric derivatization steps prior to the subsequent coupling event. We have developed an efficient approach for the synthesis of highly yielding and α-selective saccharide thioglycosides containing 1,2-cis-2-amino glycosidic bonds, via cationic nickel-catalyzed glycosylation of thioglycoside acceptors bearing the 2-trifluoromethylphenyl aglycon with N-phenyl trifluoroacetimidate donors. The 2-trifluoromethylphenyl group effectively blocks transfer of the anomeric sulfide group from the glycosyl acceptor to the C(2)-benzylidene donor and can be easily installed and activated. The current method also highlights the efficacy of the nickel catalyst selectively activating the C(2)-benzylidene imidate group in the presence of the anomeric sulfide group on the glycosyl acceptors. PMID:22838405

  13. Effects of hydroxyl radical scavengers KCN and CO on ultraviolet light-induced activation of crude soluble guanylate cyclase

    SciTech Connect

    Karlsson, J.O.; Axelsson, K.L.; Andersson, R.G.

    1985-01-01

    The crude soluble guanylate cyclase (GC) from bovine mesenteric artery was stimulated by ultraviolet (UV) light (366 nm). Addition of free radical scavengers, dimethylsulfoxide or superoxide dismutase and/or catalase to the GC assay did not abolish the stimulatory effect of UV light. On the contrary, the UV light-induced activation was enhanced in the presence of these scavengers. KCN (1 mM) did not affect the UV light-induced activation, while 0.1 mM of CO potentiated the activation. These results may indicate that UV light is operating through a direct interaction with the ferrous form of the GC-heme.

  14. Specificity of acceptor binding to Leuconostoc mesenteroides B-512F dextransucrase: binding and acceptor-product structure of alpha-methyl-D-glucopyranoside analogs modified at C-2, C-3, and C-4 by inversion of the hydroxyl and by replacement of the hydroxyl with hydrogen.

    PubMed

    Fu, D T; Slodki, M E; Robyt, J F

    1990-02-01

    The specificity of acceptor binding to the active site of dextransucrase was studied by using alpha-methyl-D-glucopyranoside analogs modified at C-2, C-3, and C-4 positions by (a) inversion of the hydroxyl group and (b) replacement of the hydroxyl group with hydrogen. 2-Deoxy-alpha-methyl-D-glucopyranoside was synthesized from 2-deoxyglucose; 3- and 4-deoxy-alpha-methyl-D-glucopyranosides were synthesized from alpha-methyl-D-glucopyranoside; and alpha-methyl-D-allopyranoside was synthesized from D-glucose. The analogs were incubated with [14C]sucrose and dextransucrase, and the products were separated by thin-layer chromatography and quantitated by liquid scintillation spectrometry. Structures of the acceptor products were determined by methylation analyses and optical rotation. The relative effectiveness of the acceptor analogs in decreasing order were 2-deoxy, 2-inverted, 3-deoxy, 3-inverted, 4-inverted, and 4-deoxy. The enzyme transfers D-glucopyranose to the C-6 hydroxyl of analogs modified at C-2 and C-3, to the C-4 hydroxyl of 4-inverted, and to the C-3 hydroxyl of 4-deoxy analogs of alpha-methyl-D-glucopyranoside. The data indicate that the hydroxyl group at C-2 is not as important for acceptor binding as the hydroxyl groups at C-3 and C-4. The hydroxyl group at C-4 is particularly important as it determines the binding orientation of the alpha-methyl-D-glucopyranoside ring.

  15. Molecular docking, molecular dynamics simulation, and structure-based 3D-QSAR studies on the aryl hydrocarbon receptor agonistic activity of hydroxylated polychlorinated biphenyls.

    PubMed

    Cao, Fu; Li, Xiaolin; Ye, Li; Xie, Yuwei; Wang, Xiaoxiang; Shi, Wei; Qian, Xiangping; Zhu, Yongliang; Yu, Hongxia

    2013-09-01

    The binding interactions between hydroxylated polychlorinated biphenyls (HO-PCBs) and the aryl hydrocarbon receptor (AhR) are suspected of causing toxic effects. To understand the binding mode between HO-PCBs and AhR, and to explore the structural characteristics that influence the AhR agonistic activities of HO-PCBs, the combination of molecular docking, three-dimensional quantitative structure-activity relationship (3D-QSAR), and molecular dynamics (MD) simulations was performed. Using molecular docking, the HO-PCBs were docked into the binding pocket of AhR, which was generated by homology modeling. Comparative molecular similarity index analysis (CoMSIA) models were subsequently developed from three different alignment rules. The optimum 3D-QSAR model showed good predictive ability (q(2)=0.583, R(2)=0.913) and good mechanism interpretability. The statistical reliability of the CoMSIA model was also validated. In addition, molecular docking and MD simulations were applied to explore the binding modes between the ligands and AhR. The results obtained from this study may lead to a better understanding of the interaction mechanism between HO-PCBs and AhR.

  16. Fatty acid hydroxylation in rat kidney cortex microsomes.

    PubMed

    Ellin, A; Orrenius, S

    1975-08-30

    Rat kidney microsomes have been found to catalyze the hydroxylation of medium-chained fatty acids to the omega- and (omego-1)-hydroxy derivatives. This reaction, which requires NADPH and molecular oxygen, is a function of monooxygenase system present in the kidney microsomes, containing NADPH-cytochrome c reductase and cytochrome P-450K. NADH is about half as effective as an electron donor as NADPH and there is an additive effect in the presence of both nucleotides. Cytochrome P-450K absorbs light maximally at 452-3 nm, when it is reduced and bound to carbon monoxide. The extinction coefficient of this complex is 91 mM(-1) cm(-1). Electrons from NADPH are transferred to cytochrome P-450K via the NADPH-cytochrome c reductase. The reduction rate of cytochrome P-450K is stimulated by added fatty acids and the reduction kinetics reveal the presence of endogenous substrates bound to cytochrome P-450K. Both cytochrome P-450K concentration and fatty acid hydroxylation activity in kidney microsomes are increased by starvation. On the other hand, phenobarbital treatment of the rats has no effect on either the hemoprotein or the overall hydroxylation reaction and 3,4-benzpyrene administration induces a new species of cytochrome P-450K not involved in fatty acid hydroxylation. Cytochrome P-450K shows, in contrast to liver P-450, high substrate specificity. The only substances forming enzyme-substrate complexes with cytochrome P-450K are the medium-chained fatty acids and certain derivatives of these acids. The chemical requirements for substrate binding include a carbon chain of medium length and at the end of the chain a carbonyl group and a free electron pair on a neighbouring atom. The distance between the binding site for the carbonyl group and the active oxygen is suggested to be in the order of 16 A. This distance fixes the ratio of omega- and (omega-1)-hydroxylated products formed from a certain fatty acid by the single species of cytochrome P-450K involved. The

  17. Prediction of cloud condensation nuclei activity for organic compounds using functional group contribution methods

    DOE PAGES

    Petters, M. D.; Kreidenweis, S. M.; Ziemann, P. J.

    2016-01-19

    A wealth of recent laboratory and field experiments demonstrate that organic aerosol composition evolves with time in the atmosphere, leading to changes in the influence of the organic fraction to cloud condensation nuclei (CCN) spectra. There is a need for tools that can realistically represent the evolution of CCN activity to better predict indirect effects of organic aerosol on clouds and climate. This work describes a model to predict the CCN activity of organic compounds from functional group composition. Following previous methods in the literature, we test the ability of semi-empirical group contribution methods in Köhler theory to predict themore » effective hygroscopicity parameter, kappa. However, in our approach we also account for liquid–liquid phase boundaries to simulate phase-limited activation behavior. Model evaluation against a selected database of published laboratory measurements demonstrates that kappa can be predicted within a factor of 2. Simulation of homologous series is used to identify the relative effectiveness of different functional groups in increasing the CCN activity of weakly functionalized organic compounds. Hydroxyl, carboxyl, aldehyde, hydroperoxide, carbonyl, and ether moieties promote CCN activity while methylene and nitrate moieties inhibit CCN activity. The model can be incorporated into scale-bridging test beds such as the Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere (GECKO-A) to evaluate the evolution of kappa for a complex mix of organic compounds and to develop suitable parameterizations of CCN evolution for larger-scale models.« less

  18. Prediction of cloud condensation nuclei activity for organic compounds using functional group contribution methods

    NASA Astrophysics Data System (ADS)

    Petters, M. D.; Kreidenweis, S. M.; Ziemann, P. J.

    2016-01-01

    A wealth of recent laboratory and field experiments demonstrate that organic aerosol composition evolves with time in the atmosphere, leading to changes in the influence of the organic fraction to cloud condensation nuclei (CCN) spectra. There is a need for tools that can realistically represent the evolution of CCN activity to better predict indirect effects of organic aerosol on clouds and climate. This work describes a model to predict the CCN activity of organic compounds from functional group composition. Following previous methods in the literature, we test the ability of semi-empirical group contribution methods in Köhler theory to predict the effective hygroscopicity parameter, kappa. However, in our approach we also account for liquid-liquid phase boundaries to simulate phase-limited activation behavior. Model evaluation against a selected database of published laboratory measurements demonstrates that kappa can be predicted within a factor of 2. Simulation of homologous series is used to identify the relative effectiveness of different functional groups in increasing the CCN activity of weakly functionalized organic compounds. Hydroxyl, carboxyl, aldehyde, hydroperoxide, carbonyl, and ether moieties promote CCN activity while methylene and nitrate moieties inhibit CCN activity. The model can be incorporated into scale-bridging test beds such as the Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere (GECKO-A) to evaluate the evolution of kappa for a complex mix of organic compounds and to develop suitable parameterizations of CCN evolution for larger-scale models.

  19. Molecular docking, molecular dynamics simulation, and structure-based 3D-QSAR studies on estrogenic activity of hydroxylated polychlorinated biphenyls.

    PubMed

    Li, Xiaolin; Ye, Li; Wang, Xiaoxiang; Wang, Xinzhou; Liu, Hongling; Qian, Xiangping; Zhu, Yongliang; Yu, Hongxia

    2012-12-15

    Hydroxylated polychlorinated biphenyls (HO-PCBs), major metabolites of PCBs, have been reported to present agonist or antagonist interactions with estrogen receptor α (ERα) and induce ER-mediated responses. In this work, a multistep framework combining molecular docking, molecular dynamics (MD) simulations, and structure-based three-dimensional quantitative structure-activity relationship (3D-QSAR) studies were performed to explore the influence of structural features on the estrogenic activities of HO-PCBs, and to investigate the molecular mechanism of ERα-ligand interactions. The CoMSIA (comparative molecular similarity indices analysis) model was developed from the conformations obtained from molecular docking. The model exhibited statistically significant results as the cross-validated correlation coefficient q² was 0.648, the non-cross-validated correlation coefficient r² was 0.968, and the external predictive correlation coefficient r(pred)² was 0.625. The key amino acid residues were identified by molecular docking, and the detailed binding modes of the compounds with different activities were determined by MD simulations. The binding free energies correlated well with the experimental activity. An energetic analysis, MM-GBSA energy decomposition, revealed that the van der Waals interaction was the major driving force for the binding of compounds to ERα. The hydrogen bond interactions between the ligands and residue His524 help to stabilize the conformation of ligands at the binding pocket. These results are expected to be beneficial to predict estrogenic activities of other HO-PCB congeners and helpful for understanding the binding mechanism of HO-PCBs and ERα. PMID:23137989

  20. Group Work vs. Whole Class Activity

    ERIC Educational Resources Information Center

    Tanveer, Asma

    2008-01-01

    Group work has only been recently introduced in the education system of Pakistan but many primary teachers, especially in the public schools, are still not aware of how different kinds of strategies that is group work and whole class teaching facilitate learning among students. This paper aims to provide an overview of teaching strategies to…

  1. Modifications of the 7-Hydroxyl Group of the Transthyretin Ligand Luteolin Provide Mechanistic Insights into Its Binding Properties and High Plasma Specificity

    PubMed Central

    Nilsson, Lina; Larsson, Andreas; Begum, Afshan; Iakovleva, Irina; Carlsson, Marcus; Brännström, Kristoffer; Sauer-Eriksson, A. Elisabeth; Olofsson, Anders

    2016-01-01

    Amyloid formation of the plasma protein transthyretin (TTR) has been linked to familial amyloid polyneuropathy and senile systemic amyloidosis. Binding of ligands within its natural hormone binding site can stabilize the tetrameric structure and impair amyloid formation. We have recently shown that the flavonoid luteolin stabilizes TTR in human plasma with a very high selectivity. Luteolin, however, is inactivated in vivo via glucuronidation for which the preferred site is the hydroxy group at position 7 on its aromatic A-ring. We have evaluated the properties of two luteolin variants in which the 7-hydroxy group has been exchanged for a chlorine (7-Cl-Lut) or a methoxy group (7-MeO-Lut). Using an in vitro model, based on human liver microsomes, we verified that these modifications increase the persistence of the drug. Crystal structure determinations show that 7-Cl-Lut binds similarly to luteolin. The larger MeO substituent cannot be accommodated within the same space as the chlorine or hydroxy group and as a result 7-MeO-Lut binds in the opposite direction with the methoxy group in position 7 facing the solvent. Both 7-Cl-Lut and 7-MeO-Lut qualify as high-affinity binders, but in contrast to luteolin, they display a highly non-specific binding to other plasma components. The binding of the two conformations and the key-interactions to TTR are discussed in detail. Taken together, these results show a proof-of-concept that the persistence of luteolin towards enzymatic modification can be increased. We reveal two alternative high-affinity binding modes of luteolin to TTR and that modification in position 7 is restricted only to small substituents if the original orientation of luteolin should be preserved. In addition, the present work provides a general and convenient method to evaluate the efficacy of TTR-stabilizing drugs under conditions similar to an in vivo environment. PMID:27050398

  2. Modifications of the 7-Hydroxyl Group of the Transthyretin Ligand Luteolin Provide Mechanistic Insights into Its Binding Properties and High Plasma Specificity.

    PubMed

    Nilsson, Lina; Larsson, Andreas; Begum, Afshan; Iakovleva, Irina; Carlsson, Marcus; Brännström, Kristoffer; Sauer-Eriksson, A Elisabeth; Olofsson, Anders

    2016-01-01

    Amyloid formation of the plasma protein transthyretin (TTR) has been linked to familial amyloid polyneuropathy and senile systemic amyloidosis. Binding of ligands within its natural hormone binding site can stabilize the tetrameric structure and impair amyloid formation. We have recently shown that the flavonoid luteolin stabilizes TTR in human plasma with a very high selectivity. Luteolin, however, is inactivated in vivo via glucuronidation for which the preferred site is the hydroxy group at position 7 on its aromatic A-ring. We have evaluated the properties of two luteolin variants in which the 7-hydroxy group has been exchanged for a chlorine (7-Cl-Lut) or a methoxy group (7-MeO-Lut). Using an in vitro model, based on human liver microsomes, we verified that these modifications increase the persistence of the drug. Crystal structure determinations show that 7-Cl-Lut binds similarly to luteolin. The larger MeO substituent cannot be accommodated within the same space as the chlorine or hydroxy group and as a result 7-MeO-Lut binds in the opposite direction with the methoxy group in position 7 facing the solvent. Both 7-Cl-Lut and 7-MeO-Lut qualify as high-affinity binders, but in contrast to luteolin, they display a highly non-specific binding to other plasma components. The binding of the two conformations and the key-interactions to TTR are discussed in detail. Taken together, these results show a proof-of-concept that the persistence of luteolin towards enzymatic modification can be increased. We reveal two alternative high-affinity binding modes of luteolin to TTR and that modification in position 7 is restricted only to small substituents if the original orientation of luteolin should be preserved. In addition, the present work provides a general and convenient method to evaluate the efficacy of TTR-stabilizing drugs under conditions similar to an in vivo environment. PMID:27050398

  3. Visible light activity of pulsed layer deposited BiVO4/MnO2 films decorated with gold nanoparticles: The evidence for hydroxyl radicals formation

    NASA Astrophysics Data System (ADS)

    Trzciński, Konrad; Szkoda, Mariusz; Sawczak, Mirosław; Karczewski, Jakub; Lisowska-Oleksiak, Anna

    2016-11-01

    Thin films containing BiVO4 and MnO2 deposited on FTO and modified by Au nanoparticles were studied towards their photoelectrochemical and photocatalytical activities in an aqueous electrolyte. Electrodes were prepared by the pulsed laser deposition (PLD) method. The surfactant-free ablation process was used for preparation of the gold nanoparticles (GNP) water suspension. Obtained layers of varied thicknesses (27-115 nm) were characterized using Raman spectroscopy, UV-vis spectroscopy and scanning electron microscopy. Electrochemical methods such as electrochemical impedance spectroscopy, linear voltammetry and chronoamperometry under visible light illumination and in the dark were applied to characterize layers as photoanodes. Simple modification of the BiVO4 + MnO2 layer by drop-casting of small amount of colloidal gold (1.5 × 10-14 mol of GNP on 1 cm2) leads to enhancement of the generated photocurrent recorded at E = 0.5 V vs. Ag/AgCl (0.1 M KCl) from 63 μA/cm2 to 280 μA/cm2. Photocatalytical studies were also exploited towards decomposition of methylene blue (MB). A possible mechanism of MB photodegradation was proposed. The formation of hydroxyl radicals was detected by photoluminescence spectra using terephthalic acid as the probe molecule.

  4. Degradation of pentachlorophenol by hydroxyl radicals and sulfate radicals using electrochemical activation of peroxomonosulfate, peroxodisulfate and hydrogen peroxide.

    PubMed

    Govindan, Kadarkarai; Raja, Mohan; Noel, Michael; James, E J

    2014-05-15

    The present study is to investigate the reactivity of free radicals (SO4(-) and HO) generated from common oxidants (peroxomonosulfate (PMS), peroxodisulfate (PDS) and hydrogen peroxide (HP)) activated by electrochemically generated Fe(2+)/Fe(3+) ions which furthermore are evaluated to destroy pentachlorophenol (PCP) in aqueous solution. The effect of solution pH and amount of oxidants (PMS, PDS and HP) in electrocoagulation (EC) on PCP degradation is analyzed in detail. The experimental results reveal that, optimum initial solution pH is 4.5 and PMS is more efficient oxidant addition in EC. 75% PCP degradation is achieved at 60min electrolysis time from PMS assisted EC. According to the first order rate constant, faster PCP degradation rate is obtained by PMS assisted EC. The PCP degradation rate by oxidant assisted EC is observed in the following order: EC/PMS>EC/PDS>EC/HP>EC. Further to identify the influences of experimental factors involved in PCP degradation by oxidant assisted EC, an experimental design based on an orthogonal array (OA) L9 (3(3)) is proposed using Taguchi method. The factors that most significantly affect the process robustness are identified as A (oxidant) and B (pH) which together account for nearly 86% of the variance.

  5. Probing the human estrogen receptor-α binding requirements for phenolic mono- and di-hydroxyl compounds: a combined synthesis, binding and docking study.

    PubMed

    McCullough, Christopher; Neumann, Terrence S; Gone, Jayapal Reddy; He, Zhengjie; Herrild, Christian; Wondergem Nee Lukesh, Julie; Pandey, Rajesh K; Donaldson, William A; Sem, Daniel S

    2014-01-01

    Various estrogen analogs were synthesized and tested for binding to human ERα using a fluorescence polarization displacement assay. Binding affinity and orientation were also predicted using docking calculations. Docking was able to accurately predict relative binding affinity and orientation for estradiol, but only if a tightly bound water molecule bridging Arg394/Glu353 is present. Di-hydroxyl compounds sometimes bind in two orientations, which are flipped in terms of relative positioning of their hydroxyl groups. Di-hydroxyl compounds were predicted to bind with their aliphatic hydroxyl group interacting with His524 in ERα. One nonsteroid-based dihdroxyl compound was 1000-fold specific for ERβ over ERα, and was also 25-fold specific for agonist ERβ versus antagonist activity. Docking predictions suggest this specificity may be due to interaction of the aliphatic hydroxyl with His475 in the agonist form of ERβ, versus with Thr299 in the antagonist form. But, the presence of this aliphatic hydroxyl is not required in all compounds, since mono-hydroxyl (phenolic) compounds bind ERα with high affinity, via hydroxyl hydrogen bonding interactions with the ERα Arg394/Glu353/water triad, and van der Waals interactions with the rest of the molecule.

  6. Combined 3D-QSAR, molecular docking and molecular dynamics study on thyroid hormone activity of hydroxylated polybrominated diphenyl ethers to thyroid receptors β

    SciTech Connect

    Li, Xiaolin; Ye, Li; Wang, Xiaoxiang; Wang, Xinzhou; Liu, Hongling; Zhu, Yongliang; Yu, Hongxia

    2012-12-15

    Several recent reports suggested that hydroxylated polybrominated diphenyl ethers (HO-PBDEs) may disturb thyroid hormone homeostasis. To illuminate the structural features for thyroid hormone activity of HO-PBDEs and the binding mode between HO-PBDEs and thyroid hormone receptor (TR), the hormone activity of a series of HO-PBDEs to thyroid receptors β was studied based on the combination of 3D-QSAR, molecular docking, and molecular dynamics (MD) methods. The ligand- and receptor-based 3D-QSAR models were obtained using Comparative Molecular Similarity Index Analysis (CoMSIA) method. The optimum CoMSIA model with region focusing yielded satisfactory statistical results: leave-one-out cross-validation correlation coefficient (q{sup 2}) was 0.571 and non-cross-validation correlation coefficient (r{sup 2}) was 0.951. Furthermore, the results of internal validation such as bootstrapping, leave-many-out cross-validation, and progressive scrambling as well as external validation indicated the rationality and good predictive ability of the best model. In addition, molecular docking elucidated the conformations of compounds and key amino acid residues at the docking pocket, MD simulation further determined the binding process and validated the rationality of docking results. -- Highlights: ► The thyroid hormone activities of HO-PBDEs were studied by 3D-QSAR. ► The binding modes between HO-PBDEs and TRβ were explored. ► 3D-QSAR, molecular docking, and molecular dynamics (MD) methods were performed.

  7. DOING Physics--Physics Activities for Groups.

    ERIC Educational Resources Information Center

    Zwicker, Earl, Ed.

    1984-01-01

    Describes an activity which demonstrates standing waves in air generated by a loudspeaker driven by an audio oscillator. The waves are detected by cool spots on a glowing nichrome wire contained in an inexpensive piece of equipment. Also describes activities involving analysis of kinematics through data taking and graphing. (JM)

  8. DOING Physics--Physics Activities for Groups.

    ERIC Educational Resources Information Center

    Green, Glenn; Insley, Peter

    1985-01-01

    Explains two activities: (1) a "rotator demonstration" (a turntable, pendulum, chalk, and other materials), which can be used in many activities to demonstrate rotational concepts; and (2) an "Eskimo yo-yo," consisting of two balls (plus long strings and a glass tube) which rotate in opposite directions to show centripetal force. (JN)

  9. Structure-activity relationships for hydroxylated polychlorinated biphenyls as inhibitors of the sulfation of dehydroepiandrosterone catalyzed by human hydroxysteroid sulfotransferase SULT2A1.

    PubMed

    Ekuase, Edugie J; Liu, Yungang; Lehmler, Hans-Joachim; Robertson, Larry W; Duffel, Michael W

    2011-10-17

    Polychlorinated biphenyls (PCBs) are persistent worldwide pollutants that are of concern due to their bioaccumulation and health effects. Metabolic oxidation of PCBs results in the formation of hydroxylated metabolites (OHPCBs). Among their biological effects, OHPCBs have been shown to alter the metabolism of endocrine hormones, including inhibition of mammalian cytosolic sulfotransferases (SULTs) that are responsible for the inactivation of thyroid hormones and phenolic steroids (i.e., hSULT1A1, hSULT1B1, and hSULT1E1). OHPCBs also interact with a human hydroxysteroid sulfotransferase that plays a role in the sulfation of endogenous alcohol-containing steroid hormones and bile acids (i.e., hSULT2A1). The objectives of our current study were to examine the effects of a series of OHPCB congeners on the activity of hSULT2A1 and to develop a three-dimensional quantitative structure-activity relationship (3D-QSAR) model for OHPCBs as inhibitors of the enzyme. A total of 15 OHPCBs were examined, and the sulfation of 1 μM [(3)H] dehydroepiandrosterone (DHEA) was utilized as a model reaction catalyzed by the enzyme. All 15 OHPCBs inhibited the sulfation of DHEA, with IC(50) values ranging from 0.6 μM to 96 μM, and eight of these OHPCBs were also substrates for the enzyme. Comparative molecular field analysis (CoMFA) provided a predictive 3D-QSAR model with a q(2) value of 0.697 and an r(2) value of 0.949. The OHPCBs that had the highest potency as inhibitors of DHEA sulfation were those with a 3, 5-dichloro-4-hydroxy substitution pattern on the biphenyl ring system, and these congeners were also substrates for sulfation catalyzed by hSULT2A1.

  10. Mountain Biking with Groups: A "Safe" Activity?

    ERIC Educational Resources Information Center

    Allen, Terry

    2001-01-01

    A survey mailed to 200 British mountain bike leaders found that rates of cycling accidents and injuries were greater in forests and woodlands than on terrain where a license is required to lead groups of young cyclists. Excessive speed was mentioned in most accidents, coupled with poor use of breaks in many cases. (SV)

  11. Group Learning as Relational Economic Activity

    ERIC Educational Resources Information Center

    Saito, Eisuke; Atencio, Matthew

    2014-01-01

    The purpose of this paper is to discuss group learning in line with economic perspectives of embeddedness and integration emanating from the work of Karl Polanyi. Polanyi's work defines economy as a necessary interaction among human beings for survival; the economy is considered inextricably linked from broader society and social relations…

  12. Ultraviolet irradiation-induced substitution of fluorine with hydroxyl radical for mass spectrometric analysis of perfluorooctane sulfonyl fluoride.

    PubMed

    Wang, Peng; Tang, Xuemei; Huang, Lulu; Kang, Jie; Zhong, Hongying

    2016-01-28

    A rapid and solvent free substitution reaction of a fluorine atom in perfluorooctane sulfonyl fluoride (PFOSF) with a hydroxyl radical is reported. Under irradiation of ultraviolet laser on semiconductor nanoparticles or metal surfaces, hydroxyl radicals can be generated through hole oxidization. Among all fluorine atoms of PFOSF, highly active hydroxyl radicals specifically substitute the fluorine of sulfonyl fluoride functional group. Resultant perfluorooctane sulfonic acid is further ionized through capture of photo-generated electrons that switch the neutral molecules to negatively charged odd electron hypervalent ions. The unpaired electron subsequently initiates α O-H bond cleavage and produces perfluorooctane sulfonate negative ions. Hydroxyl radical substitution and molecular dissociation of PFOSF have been confirmed by masses with high accuracy and resolution. It has been applied to direct mass spectrometric imaging of PFOSF adsorbed on surfaces of plant leaves.

  13. Ultraviolet irradiation-induced substitution of fluorine with hydroxyl radical for mass spectrometric analysis of perfluorooctane sulfonyl fluoride.

    PubMed

    Wang, Peng; Tang, Xuemei; Huang, Lulu; Kang, Jie; Zhong, Hongying

    2016-01-28

    A rapid and solvent free substitution reaction of a fluorine atom in perfluorooctane sulfonyl fluoride (PFOSF) with a hydroxyl radical is reported. Under irradiation of ultraviolet laser on semiconductor nanoparticles or metal surfaces, hydroxyl radicals can be generated through hole oxidization. Among all fluorine atoms of PFOSF, highly active hydroxyl radicals specifically substitute the fluorine of sulfonyl fluoride functional group. Resultant perfluorooctane sulfonic acid is further ionized through capture of photo-generated electrons that switch the neutral molecules to negatively charged odd electron hypervalent ions. The unpaired electron subsequently initiates α O-H bond cleavage and produces perfluorooctane sulfonate negative ions. Hydroxyl radical substitution and molecular dissociation of PFOSF have been confirmed by masses with high accuracy and resolution. It has been applied to direct mass spectrometric imaging of PFOSF adsorbed on surfaces of plant leaves. PMID:26755143

  14. Doing Physics--Physics Activities for Groups.

    ERIC Educational Resources Information Center

    Zwicker, Earl, Ed.

    1984-01-01

    Materials needed and procedures for conducting two activities are provided. The first investigates drops of a liquid which float on water in a watchglass resting on top of a loudspeaker. The second investigates electromagnetic phenomena. (JN)

  15. Active microwave users working group program planning

    NASA Technical Reports Server (NTRS)

    Ulaby, F. T.; Bare, J.; Brown, W. E., Jr.; Childs, L. F.; Dellwig, L. F.; Heighway, J. E.; Joosten, R.; Lewis, A. J.; Linlor, W.; Lundien, J. R.

    1978-01-01

    A detailed programmatic and technical development plan for active microwave technology was examined in each of four user activities: (1) vegetation; (2) water resources and geologic applications, and (4) oceanographic applications. Major application areas were identified, and the impact of each application area in terms of social and economic gains were evaluated. The present state of knowledge of the applicability of active microwave remote sensing to each application area was summarized and its role relative to other remote sensing devices was examined. The analysis and data acquisition techniques needed to resolve the effects of interference factors were reviewed to establish an operational capability in each application area. Flow charts of accomplished and required activities in each application area that lead to operational capability were structured.

  16. DOING Physics--Physics Activities for Groups.

    ERIC Educational Resources Information Center

    Zwicker, Earl, Ed.

    1985-01-01

    Describes three demonstrations/activities that involve forces: (1) a canoe-like boat made from copper window screen; (2) magnetic forces with a paper clip and ceramic magnetic; and (3) an "icemobile" machine that cuts ice cubes without an obvious source of energy. (DH)

  17. Post-ischaemic mild hypothermia inhibits apoptosis in the penumbral region by reducing neuronal nitric oxide synthase activity and thereby preventing endothelin-1-induced hydroxyl radical formation.

    PubMed

    Van Hemelrijck, An; Hachimi-Idrissi, Said; Sarre, Sophie; Ebinger, Guy; Michotte, Yvette

    2005-09-01

    Previously, we showed that treatment with resuscitative, post-ischaemic mild hypothermia (34 degrees C for 2 h) reduced apoptosis in the penumbra (cortex), but not in the core (striatum) of an endothelin-1 (Et-1)-induced focal cerebral infarct in the anaesthetized rat. Therefore, the purpose of this study was to investigate by which pathways resuscitative mild hypothermia exerts its neuroprotective effect in this model. The amino acids glutamate, serine, glutamine, alanine, taurine, arginine and the NO-related compound citrulline were sampled from the striatum and cortex of the ischaemic hemisphere using in vivo microdialysis. The in vivo salicylate trapping method was applied for monitoring hydroxyl radical formation via 2,3 dihydroxybenzoic acid (2,3 DHBA) detection. Caspase-3, neuronal nitric oxide synthase (nNOS) immunoreactivity and the volume of ischaemic damage were determined 24 h after the insult. In both the striatum and the cortex, Et-1-induced increases in glutamate, taurine and alanine were refractory to mild hypothermia. However, mild hypothermia significantly attenuated the ischaemia-induced 2,3 DHBA levels and the nNOS immunoreactivity in the cortex, but not in the striatum. These observations were associated with a decreased caspase-3 immunoreactivity. These results suggest that mild hypothermia exerts its neuroprotective effect in the penumbra partially by reducing nNOS activity and thereby preventing oxidative stress. Furthermore, we confirm our previous findings that the neuroprotective effect of resuscitative hypothermia is not mediated by changes in ischaemia-induced amino acid release as they could not be associated with the ischaemia-induced damage in the Et-1 rat model.

  18. Individual and group dynamics in purchasing activity

    NASA Astrophysics Data System (ADS)

    Gao, Lei; Guo, Jin-Li; Fan, Chao; Liu, Xue-Jiao

    2013-01-01

    As a major part of the daily operation in an enterprise, purchasing frequency is in constant change. Recent approaches on the human dynamics can provide some new insights into the economic behavior of companies in the supply chain. This paper captures the attributes of creation times of purchase orders to an individual vendor, as well as to all vendors, and further investigates whether they have some kind of dynamics by applying logarithmic binning to the construction of distribution plots. It’s found that the former displays a power-law distribution with approximate exponent 2.0, while the latter is fitted by a mixture distribution with both power-law and exponential characteristics. Obviously, two distinctive characteristics are presented for the interval time distribution from the perspective of individual dynamics and group dynamics. Actually, this mixing feature can be attributed to the fitting deviations as they are negligible for individual dynamics, but those of different vendors are cumulated and then lead to an exponential factor for group dynamics. To better describe the mechanism generating the heterogeneity of the purchase order assignment process from the objective company to all its vendors, a model driven by product life cycle is introduced, and then the analytical distribution and the simulation result are obtained, which are in good agreement with the empirical data.

  19. Identification, Synthesis, and Biological Evaluation of Metabolites of the Experimental Cancer Treatment Drugs Indotecan (LMP400) and Indimitecan (LMP776) and Investigation of Isomerically Hydroxylated Indenoisoquinoline Analogues as Topoisomerase I Poisons

    PubMed Central

    Cinelli, Maris A.; Reddy, P.V. Narasimha; Lv, Peng-Cheng; Liang, Jian-Hua; Chen, Lian; Agama, Keli; Pommier, Yves; van Breemen, Richard B.; Cushman, Mark

    2012-01-01

    Hydroxylated analogues of the anticancer topoisomerase I (Top1) inhibitors indotecan (LMP400) and indimitecan (LMP76) have been prepared because: 1) a variety of potent Top1 poisons are known that contain strategically placed hydroxyl groups, which provides a clear rationale for incorporating them in the present case, and 2) the hydroxylated compounds could conceivably serve as synthetic standards for the identification of metabolites. Indeed, incubating LMP400 and LMP776 with human liver microsomes resulted in two major metabolites of each drug, which had HPLC retention times and mass fragmentation patterns identical to the synthetic standards. The hydroxylated indotecan and indimitecan metabolites and analogues were tested as Top1 poisons and for antiproliferative activity in a variety of human cancer cell cultures, and in general were found to be very potent. Differences in activity resulting from the placement of the hydroxyl group are explained by molecular modeling analyses. PMID:23215354

  20. Formation of nanostructured Group IIA metal activated sensors: The transformation of Group IIA metal compound sites

    NASA Astrophysics Data System (ADS)

    Tune, Travis C.; Baker, Caitlin; Hardy, Neil; Lin, Arthur; Widing, Timothy J.; Gole, James L.

    2015-05-01

    Trends in the Group IIA metal oxides and hydroxides of magnesium, calcium, and barium are unique in the periodic table. In this study we find that they display novel trends as decorating nanostructures for extrinsic semiconductor interfaces. The Group IIA metal ions are strong Lewis acids. We form these M2+ ions in aqueous solution and bring these solutions in contact with a porous silicon interface to form interfaces for conductometric measurements. Observed responses are consistent with the formation of MgO whereas the heavier elements display behaviors which suggest the effect of their more basic nature. Mg(OH)2, when formed, represents a weak base whereas the heavier metal hydroxides of Ca, Sr, and Ba are strong bases. However, the hydroxides tend to give up hydrogen and act as Brönsted acids. For the latter elements, the reversible interaction response of nanostructures deposited to the porous silicon (PS) interface is modified, as the formation of more basic sites appears to compete with M2+ Lewis acidity and hydroxide Brönsted acidity. Mg2+ forms an interface whose response to the analytes NH3 and NO is consistent with MgO and well explained by the recently developing Inverse Hard/Soft Acid/Base model. The behavior of the Ca2+ and Ba2+ decorated interfaces as they interact with the hard base NH3 follows a reversal of the model, indicating a decrease in acidic character as the observed conductometric response suggests the interaction with hydroxyl groups. A change from oxide-like to hydroxide-like constituents is supported by XPS studies. The changes in conductometric response is easily monitored in contrast to changes associated with the Group IIA oxides and hydroxides observed in XPS, EDAX, IR, and NMR measurements.

  1. Activities of the Boom and Chassis Group

    NASA Technical Reports Server (NTRS)

    Dell, Jason Scott; Meeks, Thomas Bayne; Merkel, Kelly; Nelson, Brent; Winchell, Tom

    1992-01-01

    Group One of the NASA Lunar Enabler Project has designed the primary chassis and boom structures for the lunar vehicle. Both components also feature V-clamps that were adapted to interface connections within the structure. The chassis features a front end, rear end section, middle cross-section, and face plate. The rear section contains an extra compartment for the engine, hydraulic pump, fuel bottles, and oil reservoir necessary for the wheel drives. Each section consists of tubular aluminum 6061-T6. The boom features four degrees of freedom system, where the minimum factor of safety of any part is 1.5 (but, normally much higher). It consists of a tapered upper boom, lower boom, and three elbows that complement the articulation joints. Each section of the boom has been constructed from aluminum 6061-T6. There are four joints and eight V-clamps in the boom assembly. The V-clamps feature support rings that prevent axial rotation. They provide easy adaptability and assembly.

  2. Activities of the Boom and Chassis Group

    NASA Astrophysics Data System (ADS)

    dell, Jason Scott; Meeks, Thomas Bayne; Merkel, Kelly; Nelson, Brent; Winchell, Tom

    Group One of the NASA Lunar Enabler Project has designed the primary chassis and boom structures for the lunar vehicle. Both components also feature V-clamps that were adapted to interface connections within the structure. The chassis features a front end, rear end section, middle cross-section, and face plate. The rear section contains an extra compartment for the engine, hydraulic pump, fuel bottles, and oil reservoir necessary for the wheel drives. Each section consists of tubular aluminum 6061-T6. The boom features four degrees of freedom system, where the minimum factor of safety of any part is 1.5 (but, normally much higher). It consists of a tapered upper boom, lower boom, and three elbows that complement the articulation joints. Each section of the boom has been constructed from aluminum 6061-T6. There are four joints and eight V-clamps in the boom assembly. The V-clamps feature support rings that prevent axial rotation. They provide easy adaptability and assembly.

  3. Peptidyl-CCA deacylation on the ribosome promoted by induced fit and the O3′-hydroxyl group of A76 of the unacylated A-site tRNA

    SciTech Connect

    Simonović, Miljan; Steitz, Thomas A.

    2008-11-24

    The last step in ribosome-catalyzed protein synthesis is the hydrolytic release of the newly formed polypeptide from the P-site bound tRNA. Hydrolysis of the ester link of the peptidyl-tRNA is stimulated normally by the binding of release factors (RFs). However, an unacylated tRNA or just CCA binding to the ribosomal A site can also stimulate deacylation under some nonphysiological conditions. Although the sequence of events is well described by biochemical studies, the structural basis of the mechanism underlying this process is not well understood. Two new structures of the large ribosomal subunit of Haloarcula marismortui complexed with a peptidyl-tRNA analog in the P site and two oligonucleotide mimics of unacylated tRNA, CCA and CA, in the A site show that the binding of either CA or CCA induces a very similar conformational change in the peptidyl-transferase center as induced by aminoacyl-CCA. However, only CCA positions a water molecule appropriately to attack the carbonyl carbon of the peptidyl-tRNA and stabilizes the proper orientation of the ester link for hydrolysis. We, thus, conclude that both the ability of the O3'-hydroxyl group of the A-site A76 to position the water and the A-site CCA induced conformational change of the PTC are critical for the catalysis of the deacylation of the peptidyl-tRNA by CCA, and perhaps, an analogous mechanism is used by RFs.

  4. Hydroxyl speciation in felsic magmas

    NASA Astrophysics Data System (ADS)

    Malfait, Wim J.; Xue, Xianyu

    2014-09-01

    The hydroxyl speciation of hydrous, metaluminous potassium and calcium aluminosilicate glasses was investigated by 27Al-1H cross polarization and quantitative 1H MAS NMR spectroscopy. Al-OH is present in both the potassium and the calcium aluminosilicate glasses and its 1H NMR partial spectrum was derived from the 27Al-1H cross polarization data. For the calcium aluminosilicate glasses, the abundance of Al-OH could not be determined because of the low spectral resolution. For the potassium aluminosilicate glasses, the fraction of Al-OH was quantified by fitting its partial spectrum to the quantitative 1H NMR spectra. The degree of aluminum avoidance and the relative tendency for Si-O-Si, Si-O-Al and Al-O-Al bonds to hydrolyze were derived from the measured species abundances. Compared to the sodium, lithium and calcium systems, potassium aluminosilicate glasses display a much stronger degree of aluminum avoidance and a stronger tendency for the Al-O-Al linkages to hydrolyze. Combining our results with those for sodium aluminosilicate glasses (Malfait and Xue, 2010a), we predict that the hydroxyl groups in rhyolitic and phonolitic magmas are predominantly present as Si-OH (84-89% and 68-78%, respectively), but with a significant fraction of Al-OH (11-16% and 22-32%, respectively). For both rhyolitic and phonolitic melts, the AlOH/(AlOH + SiOH) ratio is likely smaller than the Al/(Al + Si) ratio for the lower end of the natural temperature range but may approach the Al/(Al + Si) ratio at higher temperatures.

  5. Quantum Chemical Study on the Antioxidation Mechanism of Piceatannol and Isorhapontigenin toward Hydroxyl and Hydroperoxyl Radicals.

    PubMed

    Lu, Yang; Wang, AiHua; Shi, Peng; Zhang, Hui; Li, ZeSheng

    2015-01-01

    A systematic study of the antioxidation mechanisms behind hydroxyl (•OH) and hydroperoxyl (•OOH) radical scavenging activity of piceatannol (PIC) and isorhapontigenin (ISO) was carried out using density functional theory (DFT) method. Two reaction mechanisms, abstraction (ABS) and radical adduct formation (RAF), were discussed. A total of 24 reaction pathways of scavenging •OH and •OOH with PIC and ISO were investigated in the gas phase and solution. The thermodynamic and kinetic properties of all pathways were calculated. Based on these results, we evaluated the antioxidant activity of every active site of PIC and ISO and compared the abilities of PIC and ISO to scavenge radicals. According to our results, PIC and ISO may act as effective •OH and •OOH scavengers in organism. A4-hydroxyl group is a very important active site for PIC and ISO to scavenge radicals. The introducing of -OH or -OCH3 group to the ortho-position of A4-hydroxyl group would increase its antioxidant activity. Meanwhile, the conformational effect was researched, the results suggest that the presence and pattern of intramolecular hydrogen bond (IHB) are considerable in determining the antioxidant activity of PIC and ISO.

  6. Quantum Chemical Study on the Antioxidation Mechanism of Piceatannol and Isorhapontigenin toward Hydroxyl and Hydroperoxyl Radicals

    PubMed Central

    Lu, Yang; Wang, AiHua; Shi, Peng; Zhang, Hui; Li, ZeSheng

    2015-01-01

    A systematic study of the antioxidation mechanisms behind hydroxyl (•OH) and hydroperoxyl (•OOH) radical scavenging activity of piceatannol (PIC) and isorhapontigenin (ISO) was carried out using density functional theory (DFT) method. Two reaction mechanisms, abstraction (ABS) and radical adduct formation (RAF), were discussed. A total of 24 reaction pathways of scavenging •OH and •OOH with PIC and ISO were investigated in the gas phase and solution. The thermodynamic and kinetic properties of all pathways were calculated. Based on these results, we evaluated the antioxidant activity of every active site of PIC and ISO and compared the abilities of PIC and ISO to scavenge radicals. According to our results, PIC and ISO may act as effective •OH and •OOH scavengers in organism. A4-hydroxyl group is a very important active site for PIC and ISO to scavenge radicals. The introducing of -OH or -OCH3 group to the ortho-position of A4-hydroxyl group would increase its antioxidant activity. Meanwhile, the conformational effect was researched, the results suggest that the presence and pattern of intramolecular hydrogen bond (IHB) are considerable in determining the antioxidant activity of PIC and ISO. PMID:26176778

  7. Quantum Chemical Study on the Antioxidation Mechanism of Piceatannol and Isorhapontigenin toward Hydroxyl and Hydroperoxyl Radicals.

    PubMed

    Lu, Yang; Wang, AiHua; Shi, Peng; Zhang, Hui; Li, ZeSheng

    2015-01-01

    A systematic study of the antioxidation mechanisms behind hydroxyl (•OH) and hydroperoxyl (•OOH) radical scavenging activity of piceatannol (PIC) and isorhapontigenin (ISO) was carried out using density functional theory (DFT) method. Two reaction mechanisms, abstraction (ABS) and radical adduct formation (RAF), were discussed. A total of 24 reaction pathways of scavenging •OH and •OOH with PIC and ISO were investigated in the gas phase and solution. The thermodynamic and kinetic properties of all pathways were calculated. Based on these results, we evaluated the antioxidant activity of every active site of PIC and ISO and compared the abilities of PIC and ISO to scavenge radicals. According to our results, PIC and ISO may act as effective •OH and •OOH scavengers in organism. A4-hydroxyl group is a very important active site for PIC and ISO to scavenge radicals. The introducing of -OH or -OCH3 group to the ortho-position of A4-hydroxyl group would increase its antioxidant activity. Meanwhile, the conformational effect was researched, the results suggest that the presence and pattern of intramolecular hydrogen bond (IHB) are considerable in determining the antioxidant activity of PIC and ISO. PMID:26176778

  8. Supporting "Learning by Design" Activities Using Group Blogs

    ERIC Educational Resources Information Center

    Fessakis, Georgios; Tatsis, Konstantinos; Dimitracopoulou, Angelique

    2008-01-01

    The paper presents a case study of the educational exploitation of group blogging for the implementation of a "learning by design" activity. More specifically, a group of students used a blog as a communication and information management tool in the University course of ICT-enhanced Geometry learning activities. The analysis of the designed…

  9. Teacher Educators' Design and Implementation of Group Learning Activities

    ERIC Educational Resources Information Center

    De Hei, Miranda S. A.; Sjoer, Ellen; Admiraal, Wilfried; Strijbos, Jan-Willem

    2016-01-01

    The aim of this study was to describe how teacher educators design and implement group learning activities (GLAs). We used the Group Learning Activities Instructional Design (GLAID) framework to analyse their descriptions. The GLAID framework includes eight components: (1) interaction, (2) learning objectives and outcomes, (3) assessment, (4) task…

  10. Hydroxylated PBDEs induce developmental arrest in zebrafish

    SciTech Connect

    Usenko, Crystal Y. Hopkins, David C.; Trumble, Stephen J. Bruce, Erica D.

    2012-07-01

    The ubiquitous spread of polybrominated diphenyl ethers (PBDEs) has led to concerns regarding the metabolites of these congeners, in particular hydroxylated PBDEs. There are limited studies regarding the biological interactions of these chemicals, yet there is some concern they may be more toxic than their parent compounds. In this study three hydroxylated PBDEs were assessed for toxicity in embryonic zebrafish: 3-OH-BDE 47, 5-OH-BDE 47, and 6-OH-BDE 47. All three congeners induced developmental arrest in a concentration-dependent manner; however, 6-OH-BDE 47 induced adverse effects at lower concentrations than the other congeners. Furthermore, all three induced cell death; however apoptosis was not observed. In short-term exposures (24–28 hours post fertilization), all hydroxylated PBDEs generated oxidative stress in the region corresponding to the cell death at 5 and 10 ppm. To further investigate the short-term effects that may be responsible for the developmental arrest observed in this study, gene regulation was assessed for embryos exposed to 0.625 ppm 6-OH-BDE 47 from 24 to 28 hpf. Genes involved in stress response, thyroid hormone regulation, and neurodevelopment were significantly upregulated compared to controls; however, genes related to oxidative stress were either unaffected or downregulated. This study suggests that hydroxylated PBDEs disrupt development, and may induce oxidative stress and potentially disrupt the cholinergic system and thyroid hormone homeostasis. -- Highlights: ► OH-PBDEs induce developmental arrest in a concentration-dependent manner. ► Hydroxyl group location influences biological interaction. ► OH-PBDEs induce oxidative stress. ► Thyroid hormone gene regulation was disrupted following exposure. ► To our knowledge, this is the first whole organism study of OH-PBDE toxicity.

  11. Hydroxyl-Directed Cross-Coupling: A Scalable Synthesis of Debromohamigeran E and Other Targets of Interest.

    PubMed

    Blaisdell, Thomas P; Morken, James P

    2015-07-15

    A hydroxyl functional group positioned β to a pinacol boronate can serve to direct palladium-catalyzed cross-coupling reactions. This feature can be used to control the reaction site in multiply borylated substrates and can activate boronates for reaction that would otherwise be unreactive.

  12. Towards a full understanding of the nature of Ni(II) species and hydroxyl groups over highly siliceous HZSM-5 zeolite supported nickel catalysts prepared by a deposition-precipitation method.

    PubMed

    Chen, Bao-Hui; Chao, Zi-Sheng; He, Hao; Huang, Chen; Liu, Ya-Juan; Yi, Wen-Jun; Wei, Xue-Ling; An, Jun-Fang

    2016-02-14

    Highly siliceous HZSM-5 zeolite supported nickel catalysts prepared by a deposition-precipitation (D-P) method were characterized by Fourier transform infrared (FT-IR), hydrogen temperature programmed reduction (H2-TPR), X-ray diffraction (XRD), N2-absorption/desorption, field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), and (27)Al magic-angle nuclear magnetic resonance (MAS NMR) techniques. The results showed that the D-P of nickel species occurred predominantly on the internal surface of highly siliceous HZSM-5 zeolite, in which the internal silanol groups located on the hydroxylated mesopores or nanocavities played a key role. During the D-P process, nickel hydroxide was first deposited-precipitated via olation/polymerization of neutral hydroxoaqua nickel species over the HZSM-5 zeolite. With the progress of the D-P process, 1 : 1 nickel phyllosilicate was formed over the HZSM-5 via the hetero-condensation/polymerization between charged hydroxoaqua nickel species and monomer silicic species generated due to the partial dissolution of the HZSM-5 framework. The 1 : 1 nickel phyllosilicate could also be generated via the hydrolytic adsorption of hydroxoaqua nickel species and their subsequent olation condensation. After calcination, the deposited-precipitated nickel hydroxide was decomposed into nickel oxide, while the 1 : 1 nickel phyllosilicate was transformed into 2 : 1 nickel phyllosilicate. According to the above mechanism, Ni(ii) species were present both in the form of nickel oxide and 2 : 1 nickel phyllosilicate, which were mutually separated from each other, being highly dispersed over HZSM-5 zeolite.

  13. Overview of MSFC's Applied Fluid Dynamics Analysis Group Activities

    NASA Technical Reports Server (NTRS)

    Garcia, Roberto; Griffin, Lisa; Williams, Robert

    2002-01-01

    This viewgraph report presents an overview of activities and accomplishments of NASA's Marshall Space Flight Center's Applied Fluid Dynamics Analysis Group. Expertise in this group focuses on high-fidelity fluids design and analysis with application to space shuttle propulsion and next generation launch technologies. Topics covered include: computational fluid dynamics research and goals, turbomachinery research and activities, nozzle research and activities, combustion devices, engine systems, MDA development and CFD process improvements.

  14. Group-wise FMRI Activation Detection on DICCCOL Landmarks

    PubMed Central

    Lv, Jinglei; Guo, Lei; Zhu, Dajiang; Zhang, Tuo; Hu, Xintao; Han, Junwei; Liu, Tianming

    2014-01-01

    Group-wise activation detection in task-based fMRI has been widely used because of its robustness to noises and its capacity to deal with variability of individual brains. However, current group-wise fMRI activation detection methods typically rely on the co-registration of individual brains’ fMRI images, which has difficulty in dealing with the remarkable anatomic variation of different brains. As a consequence, the resulted misalignments could significantly degrade the required inter-subject correspondences, thus substantially reducing the sensitivity and specificity of group-wise fMRI activation detection. To deal with these challenges, this paper presents a novel approach to detecting group-wise fMRI activation on our recently developed and validated Dense Individualized and Common Connectivity-based Cortical Landmarks (DICCCOL). The basic idea here is that the first-level general linear model (GLM) analysis is first performed on the fMRI signal of each corresponding DICCCOL landmark in individual brain’s own space, and then the estimated effect sizes of the same landmark from a group of subjects are statistically assessed with the mixed-effect model at the group level. Finally, the consistently activated DICCCOL landmarks are determined and declared in a group-wise fashion in response to external block-based stimuli. Our experimental results have demonstrated that the proposed approach can detect meaningful activations. PMID:24777386

  15. Chemical repair activity of free radical scavenger edaravone: reduction reactions with dGMP hydroxyl radical adducts and suppression of base lesions and AP sites on irradiated plasmid DNA.

    PubMed

    Hata, Kuniki; Urushibara, Ayumi; Yamashita, Shinichi; Lin, Mingzhang; Muroya, Yusa; Shikazono, Naoya; Yokoya, Akinari; Fu, Haiying; Katsumura, Yosuke

    2015-01-01

    Reactions of edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one) with deoxyguanosine monophosphate (dGMP) hydroxyl radical adducts were investigated by pulse radiolysis technique. Edaravone was found to reduce the dGMP hydroxyl radical adducts through electron transfer reactions. The rate constants of the reactions were greater than 4 × 10(8) dm(3) mol(-1) s(-1) and similar to those of the reactions of ascorbic acid, which is a representative antioxidant. Yields of single-strand breaks, base lesions, and abasic sites produced in pUC18 plasmid DNA by gamma ray irradiation in the presence of low concentrations (10-1000 μmol dm(-3)) of edaravone were also quantified, and the chemical repair activity of edaravone was estimated by a method recently developed by the authors. By comparing suppression efficiencies to the induction of each DNA lesion, it was found that base lesions and abasic sites were suppressed by the chemical repair activity of edaravone, although the suppression of single-strand breaks was not very effective. This phenomenon was attributed to the chemical repair activity of edaravone toward base lesions and abasic sites. However, the chemical repair activity of edaravone for base lesions was lower than that of ascorbic acid.

  16. Activity Group Therapy for Emotionally Disturbed Pre-School Children.

    ERIC Educational Resources Information Center

    Plenk, Agnes M.

    1978-01-01

    The article discusses the comprehensive services offered emotionally disturbed preschool children by a voluntary social agency (the Childrens Center in Salt Lake City, Utah), focusing on activity group therapy, the major therapeutic tool used there. (Author/DLS)

  17. Overview of MSFC's Applied Fluid Dynamics Analysis Group Activities

    NASA Technical Reports Server (NTRS)

    Garcia, Roberto; Wang, Tee-See; Griffin, Lisa; Turner, James E. (Technical Monitor)

    2001-01-01

    This document is a presentation graphic which reviews the activities of the Applied Fluid Dynamics Analysis Group at Marshall Space Flight Center (i.e., Code TD64). The work of this group focused on supporting the space transportation programs. The work of the group is in Computational Fluid Dynamic tool development. This development is driven by hardware design needs. The major applications for the design and analysis tools are: turbines, pumps, propulsion-to-airframe integration, and combustion devices.

  18. Regioselective alkane hydroxylation with a mutant AlkB enzyme

    DOEpatents

    Koch, Daniel J.; Arnold, Frances H.

    2012-11-13

    AlkB from Pseudomonas putida was engineered using in-vivo directed evolution to hydroxylate small chain alkanes. Mutant AlkB-BMO1 hydroxylates propane and butane at the terminal carbon at a rate greater than the wild-type to form 1-propanol and 1-butanol, respectively. Mutant AlkB-BMO2 similarly hydroxylates propane and butane at the terminal carbon at a rate greater than the wild-type to form 1-propanol and 1-butanol, respectively. These biocatalysts are highly active for small chain alkane substrates and their regioselectivity is retained in whole-cell biotransformations.

  19. Effects of Collaborative Activities on Group Identity in Virtual World

    ERIC Educational Resources Information Center

    Park, Hyungsung; Seo, Sumin

    2013-01-01

    The purpose of this study was to analyze the effects of collaborative activities on group identity in a virtual world such as "Second Life." To achieve this purpose, this study adopted events that promoted participants' interactions using tools inherent in "Second Life." The interactive tools given to the control group in…

  20. Implementing Small-Group Activities in Large Lecture Classes

    ERIC Educational Resources Information Center

    Yazedjian, Ani; Kolkhorst, Brittany Boyle

    2007-01-01

    This study examines student perceptions regarding the effectiveness of small-group work in a large lecture class. The article considers and illustrates from students' perspectives the ways in which small-group activities could enhance comprehension of course material, reduce anonymity associated with large lecture classes, and promote student…

  1. Bacterial metabolism of hydroxylated biphenyls.

    PubMed Central

    Higson, F K; Focht, D D

    1989-01-01

    Isolates able to grow on 3- or 4-hydroxybiphenyl (HB) as the sole carbon source were obtained by enrichment culture. The 3-HB degrader Pseudomonas sp. strain FH12 used an NADPH-dependent monooxygenase restricted to 3- and 3,3'-HBs to introduce an ortho-hydroxyl. The 4-HB degrader Pseudomonas sp. strain FH23 used either a mono- or dioxygenase to generate a 2,3-diphenolic substitution pattern which allowed meta-fission of the aromatic ring. By using 3-chlorocatechol to inhibit catechol dioxygenase activity, it was found that 2- and 3-HBs were converted by FH23 to 2,3-HB, whereas biphenyl and 4-HB were attacked by dioxygenation. 4-HB was metabolized to 2,3,4'-trihydroxybiphenyl. Neither organism attacked chlorinated HBs. The degradation of 3- and 4-HBs by these strains is therefore analogous to the metabolism of biphenyl, 2-HB, and naphthalene in the requirement for 2,3-catechol formation. PMID:2729993

  2. Overview af MSFC's Applied Fluid Dynamics Analysis Group Activities

    NASA Technical Reports Server (NTRS)

    Garcia, Roberto; Griffin, Lisa; Williams, Robert

    2004-01-01

    This paper presents viewgraphs on NASA Marshall Space Flight Center's Applied Fluid Dynamics Analysis Group Activities. The topics include: 1) Status of programs at MSFC; 2) Fluid Mechanics at MSFC; 3) Relevant Fluid Dynamics Activities at MSFC; and 4) Shuttle Return to Flight.

  3. 2'-deoxy cyclic adenosine 5'-diphosphate ribose derivatives: importance of the 2'-hydroxyl motif for the antagonistic activity of 8-substituted cADPR derivatives.

    PubMed

    Zhang, Bo; Wagner, Gerd K; Weber, Karin; Garnham, Clive; Morgan, Anthony J; Galione, Antony; Guse, Andreas H; Potter, Barry V L

    2008-03-27

    The structural features needed for antagonism at the cyclic ADP-ribose (cADPR) receptor are unclear. Chemoenzymatic syntheses of novel 8-substituted 2'-deoxy-cADPR analogues, including 8-bromo-2'-deoxy-cADPR 7, 8-amino-2'-deoxy-cADPR 8, 8- O-methyl-2'-deoxy-cADPR 9, 8-phenyl-2'-deoxy-cADPR 10 and its ribose counterpart 8-phenyl-cADPR 5 are reported, including improved syntheses of established antagonists 8-amino-cADPR 2 and 8-bromo-cADPR 3. Aplysia californica ADP-ribosyl cyclase tolerates even the bulky 8-phenyl-nicotinamide adenine 5'-dinucleotide as a substrate. Structure-activity relationships of 8-substituted cADPR analogues in both Jurkat T-lymphocytes and sea urchin egg homogenate (SUH) were investigated. 2'-OH Deletion decreased antagonistic activity (at least for the 8-amino series), showing it to be an important motif. Some 8-substituted 2'-deoxy analogues showed agonist activity at higher concentrations, among which 8-bromo-2'-deoxy-cADPR 7 was, unexpectedly, a weak but almost full agonist in SUH and was membrane-permeant in whole eggs. Classical antagonists 2 and 3 also showed previously unobserved agonist activity at higher concentrations in both systems. The 2'-OH group, without effect on the Ca (2+)-mobilizing ability of cADPR itself, is an important motif for the antagonistic activities of 8-substituted cADPR analogues. PMID:18303825

  4. A pro-chelator triggered by hydrogen peroxide inhibits iron-promoted hydroxyl radical formation.

    PubMed

    Charkoudian, Louise K; Pham, David M; Franz, Katherine J

    2006-09-27

    The synthesis and structural characterization of a new pro-chelating agent, isonicotinic acid [2-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl)-benzylidene]-hydrazide (BSIH), are presented. BSIH only weakly interacts with iron unless hydrogen peroxide (H2O2) is present to remove the boronic ester protecting group to reveal a phenol that is a key metal-binding group of tridentate salicylaldehyde isonicotinoyl hydrazone (SIH). BSIH prevents deoxyribose degradation caused by hydroxyl radicals that are generated from H2O2 and redox-active iron by sequestering Fe3+ and preventing iron-promoted hydroxyl radical formation. The rate-determining step for iron sequestration is conversion of BSIH to SIH, followed by rapid Fe3+ complexation. The pro-chelate approach of BSIH represents a promising strategy for chelating a specific pool of detrimental metal ions without disturbing healthy metal ion distribution.

  5. A pro-chelator triggered by hydrogen peroxide inhibits iron-promoted hydroxyl radical formation.

    PubMed

    Charkoudian, Louise K; Pham, David M; Franz, Katherine J

    2006-09-27

    The synthesis and structural characterization of a new pro-chelating agent, isonicotinic acid [2-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl)-benzylidene]-hydrazide (BSIH), are presented. BSIH only weakly interacts with iron unless hydrogen peroxide (H2O2) is present to remove the boronic ester protecting group to reveal a phenol that is a key metal-binding group of tridentate salicylaldehyde isonicotinoyl hydrazone (SIH). BSIH prevents deoxyribose degradation caused by hydroxyl radicals that are generated from H2O2 and redox-active iron by sequestering Fe3+ and preventing iron-promoted hydroxyl radical formation. The rate-determining step for iron sequestration is conversion of BSIH to SIH, followed by rapid Fe3+ complexation. The pro-chelate approach of BSIH represents a promising strategy for chelating a specific pool of detrimental metal ions without disturbing healthy metal ion distribution. PMID:16984186

  6. How does angiotensin II increase cardiac dopamine-beta-hydroxylation?

    PubMed

    Chevillard, C; Duchene, N; Alexandre, J M

    1975-03-01

    The potent accelerating effect of angiotensin II (Ang II) on caridac dopamine beta-hydroxylation was studied on slices of rat heart. Ang II did not affect the kinetics of beta-hydroxylation but it increased the axonal uptake of dopamine, and, concomitant with the acceleration of biosynthesis, it enhanced the accumulation of dopamine into tissue. Puromycin, in contrast to actinomycin D, antagonized the stimulation of dopamine beta-hydroxylation by Ang II, but did not suppress the rise in cardiac dopamine. Therefore, to promote the acceleration of dopamine beta-hydroxylation, (i) the rise in tissue dopamine available for conversion appeared to be insufficient, (ii) the formation of new proteins by activation of traduction seemed to constitute the basic mechanism of Ang II action.

  7. Active Classroom Participation in a Group Scribbles Primary Science Classroom

    ERIC Educational Resources Information Center

    Chen, Wenli; Looi, Chee-Kit

    2011-01-01

    A key stimulus of learning efficacy for students in the classroom is active participation and engagement in the learning process. This study examines the nature of teacher-student and student-student discourse when leveraged by an interactive technology--Group Scribbles (GS) in a Primary 5 Science classroom in Singapore which supports rapid…

  8. Forestry Activities. A Guide for Youth Group Leaders.

    ERIC Educational Resources Information Center

    Forest Service (USDA), Washington, DC.

    Twenty-six activities related to forestry, conservation, and outdoor education comprise the content of this leader's guide. Designed for use with youth groups, ideas and techniques range from forest conservation mobiles, locating forest fires, and Christmas tree uses to litterbug campaigns, watershed experiments, and crossword puzzles. Activities…

  9. Kinetics of hydrogen peroxide decomposition by catalase: hydroxylic solvent effects.

    PubMed

    Raducan, Adina; Cantemir, Anca Ruxandra; Puiu, Mihaela; Oancea, Dumitru

    2012-11-01

    The effect of water-alcohol (methanol, ethanol, propan-1-ol, propan-2-ol, ethane-1,2-diol and propane-1,2,3-triol) binary mixtures on the kinetics of hydrogen peroxide decomposition in the presence of bovine liver catalase is investigated. In all solvents, the activity of catalase is smaller than in water. The results are discussed on the basis of a simple kinetic model. The kinetic constants for product formation through enzyme-substrate complex decomposition and for inactivation of catalase are estimated. The organic solvents are characterized by several physical properties: dielectric constant (D), hydrophobicity (log P), concentration of hydroxyl groups ([OH]), polarizability (α), Kamlet-Taft parameter (β) and Kosower parameter (Z). The relationships between the initial rate, kinetic constants and medium properties are analyzed by linear and multiple linear regression.

  10. Kinetics of hydrogen peroxide decomposition by catalase: hydroxylic solvent effects.

    PubMed

    Raducan, Adina; Cantemir, Anca Ruxandra; Puiu, Mihaela; Oancea, Dumitru

    2012-11-01

    The effect of water-alcohol (methanol, ethanol, propan-1-ol, propan-2-ol, ethane-1,2-diol and propane-1,2,3-triol) binary mixtures on the kinetics of hydrogen peroxide decomposition in the presence of bovine liver catalase is investigated. In all solvents, the activity of catalase is smaller than in water. The results are discussed on the basis of a simple kinetic model. The kinetic constants for product formation through enzyme-substrate complex decomposition and for inactivation of catalase are estimated. The organic solvents are characterized by several physical properties: dielectric constant (D), hydrophobicity (log P), concentration of hydroxyl groups ([OH]), polarizability (α), Kamlet-Taft parameter (β) and Kosower parameter (Z). The relationships between the initial rate, kinetic constants and medium properties are analyzed by linear and multiple linear regression. PMID:22565543

  11. Effects of oxygen functional groups on the enhancement of the hydrogen spillover of Pd-doped activated carbon.

    PubMed

    Chung, Tsui-Yun; Tsao, Cheng-Si; Tseng, Hui-Ping; Chen, Chien-Hung; Yu, Ming-Sheng

    2015-03-01

    The hydrogen storage performance of Pd-doped oxidized activated carbon (Pd/AC-ox) with various oxygen contents or functional groups was investigated. The surface chemistry of the Pd/AC-ox sample was modified by treatment with hydrogen gas. Temperature-programmed desorption was performed to characterize the oxygen functional groups in each sample. In this study, low- and high-pressure hydrogen adsorption isotherm experiments were conducted using a static volumetric measurement at room temperature (RT) and pressures of up to 8 MPa. The results showed that increasing the oxygen content and functional groups on the surface of the Pd/AC-ox significantly improved the reversible RT hydrogen storage capacity due to the spillover effect. The hydrogen spillover enhancement factors at 0.12 MPa were greater than 100% for all samples. The hydrogen uptake of Pd/AC-ox1 at RT and 8 MPa with an oxygen content of 8.94 wt.% was 0.37 wt.%, which was 48% greater than that of Pd-free AC-ox (0.25 wt.%). In addition, the hydrogen uptake of Pd/AC-ox3 with lower oxygen contents demonstrates that the hydrogen spillover enhancement gradually disappears when the pressure is increased to more than 2 MPa (i.e., a transition from spillover to physisorption). The surface diffusion, or reversible adsorption, of the spiltover H atoms, which is enhanced by oxygen functional groups, was affected by a threshold amount of oxygen groups (such as hydroxyl groups). PMID:25490569

  12. Evolution and flare activity of a group in July 1978

    SciTech Connect

    Sattarov, I.

    1983-03-01

    The evolution of a sunspot group with a delta configuration which passed over the solar disk on July 8--21, 1978, is studied on the basis of original materials consisting of photoheliograms, H..cap alpha.. filtergrams, and wide-band photographs obtained in Tashkent. More than 160 H..cap alpha.. flares, including 22 flares of importance 1 and 10 flares of importance 2, were observed in the active region (AR) containing this group according to Solar-Geophysical Data. As a result of a comparison of the evolutionary changes of the group with the flare activity of the AR it was found that the flare activity is connected with the formation of a new sunspot group within an old one, with its maximum falling at the time of formation of the first nuclei, and new nuclei are formed along the zero line of the longitudinal field of the old group; the nodes of the majority of flares are located near new nuclei, symmetrical relative to the zero line; the area of the new nuclei increases impulsively; the total area of the entire group varies, fluctuating about its average value, and flares happen during the slowing and cessation of the increase in area; some nuclei show proper motion at a velocity of approx.0.5 km/sec while others show intermittent motion, like pulsation, directed outside the old group; as a result of the development of new nuclei near old ones the small nuclei break up, while the boundary of the large nucleus is deformed on the side of the new nuclei and bright points shine within it.

  13. Theoretical study of chlordecone and surface groups interaction in an activated carbon model under acidic and neutral conditions.

    PubMed

    Gamboa-Carballo, Juan José; Melchor-Rodríguez, Kenia; Hernández-Valdés, Daniel; Enriquez-Victorero, Carlos; Montero-Alejo, Ana Lilian; Gaspard, Sarra; Jáuregui-Haza, Ulises Javier

    2016-04-01

    Activated carbons (ACs) are widely used in the purification of drinking water without almost any knowledge about the adsorption mechanisms of the persistent organic pollutants. Chlordecone (CLD, Kepone) is an organochlorinated synthetic compound that has been used mainly as agricultural insecticide. CLD has been identified and listed as a persistent organic pollutant by the Stockholm Convention. The selection of the best suited AC for this type of contaminants is mainly an empirical and costly process. A theoretical study of the influence of AC surface groups (SGs) on CLD adsorption is done in order to help understanding the process. This may provide a first selection criteria for the preparation of AC with suitable surface properties. A model of AC consisting of a seven membered ring graphene sheet (coronene) with a functional group on the edge was used to evaluate the influence of the SGs over the adsorption. Multiple Minima Hypersurface methodology (MMH) coupled with PM7 semiempirical Hamiltonian was employed in order to study the interactions of the chlordecone with SGs (hydroxyl and carboxyl) at acidic and neutral pH and different hydration conditions. Selected structures were re-optimized using CAM-B3LYP to achieve a well-defined electron density to characterize the interactions by the Quantum Theory of Atoms in Molecules approach. The deprotonated form of surface carboxyl and hydroxyl groups of AC models show the strongest interactions, suggesting a chemical adsorption. An increase in carboxylic SGs content is proposed to enhance CLD adsorption onto AC at neutral pH conditions. PMID:26945637

  14. Theoretical study of chlordecone and surface groups interaction in an activated carbon model under acidic and neutral conditions.

    PubMed

    Gamboa-Carballo, Juan José; Melchor-Rodríguez, Kenia; Hernández-Valdés, Daniel; Enriquez-Victorero, Carlos; Montero-Alejo, Ana Lilian; Gaspard, Sarra; Jáuregui-Haza, Ulises Javier

    2016-04-01

    Activated carbons (ACs) are widely used in the purification of drinking water without almost any knowledge about the adsorption mechanisms of the persistent organic pollutants. Chlordecone (CLD, Kepone) is an organochlorinated synthetic compound that has been used mainly as agricultural insecticide. CLD has been identified and listed as a persistent organic pollutant by the Stockholm Convention. The selection of the best suited AC for this type of contaminants is mainly an empirical and costly process. A theoretical study of the influence of AC surface groups (SGs) on CLD adsorption is done in order to help understanding the process. This may provide a first selection criteria for the preparation of AC with suitable surface properties. A model of AC consisting of a seven membered ring graphene sheet (coronene) with a functional group on the edge was used to evaluate the influence of the SGs over the adsorption. Multiple Minima Hypersurface methodology (MMH) coupled with PM7 semiempirical Hamiltonian was employed in order to study the interactions of the chlordecone with SGs (hydroxyl and carboxyl) at acidic and neutral pH and different hydration conditions. Selected structures were re-optimized using CAM-B3LYP to achieve a well-defined electron density to characterize the interactions by the Quantum Theory of Atoms in Molecules approach. The deprotonated form of surface carboxyl and hydroxyl groups of AC models show the strongest interactions, suggesting a chemical adsorption. An increase in carboxylic SGs content is proposed to enhance CLD adsorption onto AC at neutral pH conditions.

  15. In-Group and Out-Group Membership Mediates Anterior Cingulate Activation to Social Exclusion

    PubMed Central

    Krill, Austen; Platek, Steven M.

    2009-01-01

    Functional magnetic resonance imaging was employed to examine sensitivity to social exclusion in three conditions: same-race, other-race, and self-resembling faces. The anterior cingulate cortex (ACC), specifically the dorsal ACC, has been targeted as a key substrate in the physical and social pain matrix and was hypothesized to regulate activation response to various facial conditions. We show that participants demonstrated greatest ACC activation when being excluded by self-resembling and same-race faces, relative to other-race faces. Additionally, participants expressed greater distress and showed increased ACC activation as a result of exclusion in the same-race condition relative to the other-race condition. A positive correlation between implicit racial bias and activation in the amygdala was also evident. Implicit attitude about other-race faces partly explains levels of concern about exclusion by out-group individuals. These findings suggest that individuals are more distressed and their brain (i.e. neural alarm system) responds with greater activation when being excluded by individuals whom they are more likely to share group membership with. PMID:19597546

  16. a Measurement of Hydroxyl in the Daytime Mesosphere.

    NASA Astrophysics Data System (ADS)

    Cageao, Richard Philip

    Hydroxyl is a very reactive free radical which dominates the odd-hydrogen - odd-oxygen reaction chemistry in the earth's mesosphere. The objective of this thesis was the development of an instrument which would measure the concentration of hydroxyl in the mesosphere and an assessment, based on this data, of the current understanding of mesospheric chemistry. A new instrument, a coupled Ebert-Fastie spectrometer and Fabry-Perot interferometer (UV-FPI), was developed to measure spectroscopically the ultraviolet solar resonance fluorescence emission of hydroxyl. The instrument was designed to observe these emissions in the near-ultraviolet at 3087 A against the bright background of Rayleigh scattered sunlight. The background was suppressed by the high resolution Fabry-Perot interferometer operating over the narrow wavelength region defined by the Ebert -Fastie spectrometer bandpass. The remote measurement of hydroxyl was made from a sounding rocket platform with the instrument viewing the earth's limb for the maximum integrated path length of hydroxyl emission. The sounding rocket payload also carried instruments which made simultaneous in situ and remote sensing measurements of atomic oxygen and temperature, respectively. Although the UV-FPI configuration was not optimum for measurement of the desired hydroxyl emission, upper limits could be set on the hydroxyl concentrations. The hydroxyl concentration inferred from the emission measurements was 50% lower than a previous measurement. Comparison of this result and the data for mesospheric abundances of ozone and atomic oxygen with current chemical models shows that modeled odd-hydrogen activity in the middle mesosphere must be reduced and vertical advection in the upper mesosphere must be increased in order to successfully model the chemical processes occurring in the mesosphere.

  17. Modulation of Group I Ribozyme Activity by Cationic Porphyrins

    PubMed Central

    Matsumura, Shigeyoshi; Ito, Tatsunobu; Tanaka, Takahiro; Furuta, Hiroyuki; Ikawa, Yoshiya

    2015-01-01

    The effects of cationic porphyrins on the catalytic activities of four group I ribozymes were investigated. A cationic porphyrin possessing four pyridinium moieties (pPyP) inhibited two group IC3 ribozymes (Syn Rz and Azo Rz) and a group IC1 ribozyme (Tet Rz). In the case of a group IA2 ribozyme (Td Rz), however, pPyP served not only as an inhibitor but also as an activator, and the effects of pPyP were dependent on its concentration. To analyze the structural and electronic factors determining the effects of pPyP on group I ribozymes, three cationic porphyrins (pPyNCP, pPyF4P, and TMPyP) were also examined. As interactions between small organic molecules and nucleic acids are attractive and important issues in biochemistry and biotechnology, this study contributes to the development of porphyrin-based molecules that can modulate functions of structured RNA molecules. PMID:25811638

  18. Group I fibers: pressor reflex and cardiac activity.

    PubMed

    Decandia, G F; Decandia, M; Orani, G P

    1991-09-01

    Experiments were performed on cats to see whether stimulation of group I afferent fibers from gastrocnemius-soleus muscles induced changes in cardiac activity, in addition to the increase in systemic arterial pressure already established. The results show that the increase in arterial pressure is accompanied by an increase in systolic left ventricular pressure, without any significant changes in cardiac inotropism and chronotropism. It is concluded that the cardiac innervation is not an important efferent pathway of the pressor reflex evoked by stimulating group I afferent fibers, and that the reflex increase in arterial pressure depends mainly on an increase in peripheral vascular resistance. PMID:1742468

  19. Fission Activities of the Nuclear Reactions Group in Uppsala

    NASA Astrophysics Data System (ADS)

    Al-Adili, A.; Alhassan, E.; Gustavsson, C.; Helgesson, P.; Jansson, K.; Koning, A.; Lantz, M.; Mattera, A.; Prokofiev, A. V.; Rakopoulos, V.; Sjöstrand, H.; Solders, A.; Tarrío, D.; Österlund, M.; Pomp, S.

    This paper highlights some of the main activities related to fission of the nuclear reactions group at Uppsala University. The group is involved for instance in fission yield experiments at the IGISOL facility, cross-section measurements at the NFS facility, as well as fission dynamics studies at the IRMM JRC-EC. Moreover, work is ongoing on the Total Monte Carlo (TMC) methodology and on including the GEF fission code into the TALYS nuclear reaction code. Selected results from these projects are discussed.

  20. The role of the 4''-hydroxyl on motilin agonist potency in the 9-dihydroerythromycin series.

    PubMed

    Liu, Yaoquan; Carreras, Christopher W; Claypool, Mark; Myles, David C; Shaw, Simon J

    2011-06-15

    The role of the erythromycin 4''-hydroxyl group has been explored on the motilin agonist potential in the 9-dihydroerythromycin series of motilides. The compounds show potencies 2- to 4-fold superior to the corresponding hydroxylated compounds. The relationship is maintained when the 9-hydroxyl is alkylated to generate the corresponding 4''-deoxy-9-O-acetamido-9-dihydroerythromycins. However, concomitant with this increase in potency is an increase in hERG inhibition.

  1. Ground-state, transition-state, and metal-cation effects of the 2-hydroxyl group on beta-D-galactopyranosyl transfer catalyzed by beta-galactosidase (Escherichia coli, lac Z).

    PubMed

    Richard, John P; McCall, Deborah A; Heo, Christina K; Toteva, Maria M

    2005-09-01

    Substitution of the C2-OH group by C2-H at 4-nitrophenyl-beta-d-galactopyranoside to give 4-nitrophenyl-2-deoxy-beta-d-galactopyranoside causes (1) a change in the rate-determining step for beta-galactosidase-catalyzed sugar hydrolysis from formation to breakdown of a covalent intermediate; (2) a 14 000-fold decrease in the second-order rate constant k(3)/K(d) for enzyme-catalyzed transfer of the beta-d-galactopyranosyl group from the substrate to form a covalent adduct to the enzyme; and (3) a larger 320 000-fold decrease in the first-order rate constant k(s) for hydrolysis of this covalent adduct. Only a small fraction (ca. 7%) of the 2-OH substituent effect is expressed in the ground-state Michaelis complex, so that the (apparent) strong interactions between the enzyme and 2-OH group that stabilize the transition state for beta-d-galactopyranosyl transfer only develop upon moving from the Michaelis complex to the transition state. Mg(2+) activates beta-galactosidase for cleavage of both 4-nitrophenyl-beta-d-galactopyranoside and 4-nitrophenyl-2-deoxy-beta-d-galactopyranoside. This suggests that Mg(2+) activation does not involve interactions with the 2-OH group. The removal of Mg(2+) from beta-galactosidase causes a change in the rate-determining step for enzyme-catalyzed hydrolysis of 4-nitrophenyl-2-deoxy-beta-d-galactopyranoside from breakdown to formation of the covalent intermediate. The observed 2-OH effect would require a very large (10-11 kcal/mol) stabilization of the transition state for beta-d-galactopyranosyl group transfer to water by interactions between beta-galactosidase and the neutral 2-OH group. We suggest that the apparent effect of the neutral substituent is more simply rationalized by ionization of the 2-OH to form a 2-O(-) anion, which provides effective electrostatic stabilization of the cationic transition state for glycoside cleavage at an active site of relatively low dielectric constant.

  2. Promotional effect of surface hydroxyls on electrochemical reduction of CO2 over SnOx/Sn electrode

    DOE PAGES

    Cui, Chaonan; Han, Jinyu; Zhu, Xinli; Liu, Xiao; Wang, Hua; Mei, Donghai; Ge, Qingfeng

    2016-01-16

    In this study, tin oxide (SnOx) formation on tin-based electrode surfaces during CO2 electrochemical reduction can have a significant impact on the activity and selectivity of the reaction. In the present study, density functional theory (DFT) calculations have been performed to understand the role of SnOx in CO2 reduction using a SnO monolayer on the Sn(112) surface as a model for SnOx. Water molecules have been treated explicitly and considered actively participating in the reaction. The results showed that H2O dissociates on the perfect SnO monolayer into two hydroxyl groups symmetrically on the surface. CO2 energetically prefers to react withmore » the hydroxyl, forming a bicarbonate (HCO3(t)*) intermediate, which can then be reduced to either formate (HCOO*) by hydrogenating the carbon atom or carboxyl (COOH*) by protonating the oxygen atom. Both steps involve a simultaneous Csingle bondO bond breaking. Further reduction of HCOO* species leads to the formation of formic acid in the acidic solution at pH < 4, while the COOH* will decompose to CO and H2O via protonation. Whereas the oxygen vacancy (VO) in the oxide monolayer maybe formed by the reduction, it can be recovered by H2O dissociation, resulting in two embedded hydroxyl groups. The results show that the hydroxylated surface with two symmetric hydroxyls is energetically more favorable for CO2 reduction than the hydroxylated VO surface with two embedded hydroxyls. The reduction potential for the former has a limiting-potential of –0.20 V (RHE), lower than that for the latter (–0.74 V (RHE)). Compared to the pure Sn electrode, the formation of SnOx monolayer on the electrode under the operating conditions promotes CO2 reduction more effectively by forming surface hydroxyls, thereby providing a new channel via COOH* to the CO formation, although formic acid is still the major reduction product.« less

  3. Mapping nucleic acid structure by hydroxyl radical cleavage.

    PubMed

    Tullius, Thomas D; Greenbaum, Jason A

    2005-04-01

    Hydroxyl radical footprinting is a widely used method for following the folding of RNA molecules in solution. This method has the unique ability to provide experimental information on the solvent accessibility of each nucleotide in an RNA molecule, so that the folding of all domains of the RNA species can be followed simultaneously at single-nucleotide resolution. In recent work, hydroxyl radical footprinting has been used, often in combination with other global measures of structure, to work out detailed folding pathways and three-dimensional structures for increasingly large and complicated RNA molecules. These include synthetic ribozymes, and group I and group II ribozymes, from yeast, the Azoarcus cyanobacterium and Tetrahymena thermophila. Advances have been made in methods for analysis of hydroxyl radical data, so that the large datasets that result from kinetic folding experiments can be analyzed in a semi-automated and quantitative manner.

  4. Design, synthesis, and biological evaluation of simplified analogues of (+)-discodermolide. Additional insights on the importance of the diene, the C7 hydroxyl, and the lactone.

    PubMed

    Smith, Amos B; Xian, Ming

    2005-11-10

    [structure: see text] The design, synthesis, and biological evaluation of seven totally synthetic analogues of the antitumor agent (+)-discodermolide are reported. Saturation of the terminal diene system, alteration of the substituents on the lactone, and alkylation of the C7-hydroxyl group reveal significant structure-activity relationships.

  5. Oxygen activation by the noncoupled binuclear copper site in peptidylglycine alpha-hydroxylating monooxygenase. Spectroscopic definition of the resting sites and the putative CuIIM-OOH intermediate.

    PubMed

    Chen, Peng; Bell, Joseph; Eipper, Betty A; Solomon, Edward I

    2004-05-18

    Spectroscopic methods, density functional calculations, and ligand field analyses are combined to define the geometric models and electronic structure descriptions of the Cu(M) and Cu(H) sites in the oxidized form of the noncoupled binuclear copper protein peptidylglycine alpha-hydroxylating monooxygenase (PHM). The Cu(M) site has a square pyramidal geometry with a long axial Cu-methionine bond and two histidines, H(2)O, and OH(-) as equatorial ligands. The Cu(H) site has a slightly D(2)(d) distorted square planar geometry with three histidines and H(2)O ligands. The structurally inequivalent Cu(M) and Cu(H) sites do not exhibit measurable differences in optical and electron paramagnetic resonance (EPR) spectra, which result from their similar ligand field transition energies and ground-state Cu covalencies. The additional axial methionine ligand interaction and associated square pyramidal distortion of the Cu(M) site have the opposite effect of the strong equatorial OH(-) donor ligand on the Cu d orbital splitting pattern relative to the Cu(H) site leading to similar ligand field transition energies for both sites. The small molecule NO(2)(-) binds in different coordination modes to the Cu(M) and Cu(H) site because of differences in their exchangeable coordination positions resulting in these Cu(II) sites being spectroscopically distinguishable. Azide binding to PHM is used as a spectroscopic and electronic structure analogue to OOH(-) binding to provide a starting point for developing a geometric and electronic structural model for the putative Cu(II)(M)-OOH intermediate in the H-atom abstraction reaction of PHM. Possible electronic structure contributions of the Cu(II)(M)-OOH intermediate to reactivity are considered by correlation to the well-studied L3Cu(II)-OOH model complex (L3 = [HB[3-tBu-5-iPrpz](3)]). The Met-S ligand of the Cu(M) site is found to contribute to the stabilization of the Cu(II)(M)-oxyl species, which would be a product of Cu(II)(M)-OOH H

  6. Evolving P450pyr Monooxygenase for Regio- and Stereoselective Hydroxylations.

    PubMed

    Yang, Yi; Li, Zhi

    2015-01-01

    P450pyr monooxygenase from Sphingomonas sp. HXN-200 catalysed the regio- and stereoselective hydroxylation at a non-activated carbon atom, a useful but challenging reaction in classic chemistry, with unique substrate specificity for a number of alicyclic compounds. New P450pyr mutants were developed by directed evolution with improved catalytic performance, thus significantly extending the application of the P450pyr monooxygenase family in biohydroxylation to prepare useful and valuable chiral alcohols. Directed evolution of P450pyr created new enzymes with improved S-enantioselectivity or R-enantioselectivity for the hydroxylation of N-benzyl pyrrolidine, enhanced regioselectivity for the hydroxylation of N-benzyl pyrrolidinone, and increased enantioselectivity for the hydroxylation of N-benzyl piperidinone, respectively. Directed evolution of P450pyr generated also mutants with fully altered regioselectivity (from terminal to subterminal) and newly created excellent S-enantioselectivity for the biohydroxylation of n-octane and propylbenzene, respectively, providing new opportunities for the regio- and enantioselective alkane functionalization. New P450pyr mutants were engineered as the first catalyst for highly selective terminal hydroxylation of n-butanol to 1,4-butanediol. Several novel, accurate, sensitive, simple, and HTS assays based on colorimetric or MS detection for measuring the enantio- and/or regioselectivity of hydroxylation were developed and proven to be practical in directed evolution. The P450pyr X-ray structure was obtained and used to guide the evolution. In silico modelling and substrate docking provided some insight into the influence of several important amino acid mutations of the engineered P450pyr mutants on the altered or enhanced regio- and enantioselectivity as well as new substrate acceptance. The obtained information and knowledge is useful for further engineering of P450pyr for other hydroxylations and oxidations. PMID:26507217

  7. Evolving P450pyr Monooxygenase for Regio- and Stereoselective Hydroxylations.

    PubMed

    Yang, Yi; Li, Zhi

    2015-01-01

    P450pyr monooxygenase from Sphingomonas sp. HXN-200 catalysed the regio- and stereoselective hydroxylation at a non-activated carbon atom, a useful but challenging reaction in classic chemistry, with unique substrate specificity for a number of alicyclic compounds. New P450pyr mutants were developed by directed evolution with improved catalytic performance, thus significantly extending the application of the P450pyr monooxygenase family in biohydroxylation to prepare useful and valuable chiral alcohols. Directed evolution of P450pyr created new enzymes with improved S-enantioselectivity or R-enantioselectivity for the hydroxylation of N-benzyl pyrrolidine, enhanced regioselectivity for the hydroxylation of N-benzyl pyrrolidinone, and increased enantioselectivity for the hydroxylation of N-benzyl piperidinone, respectively. Directed evolution of P450pyr generated also mutants with fully altered regioselectivity (from terminal to subterminal) and newly created excellent S-enantioselectivity for the biohydroxylation of n-octane and propylbenzene, respectively, providing new opportunities for the regio- and enantioselective alkane functionalization. New P450pyr mutants were engineered as the first catalyst for highly selective terminal hydroxylation of n-butanol to 1,4-butanediol. Several novel, accurate, sensitive, simple, and HTS assays based on colorimetric or MS detection for measuring the enantio- and/or regioselectivity of hydroxylation were developed and proven to be practical in directed evolution. The P450pyr X-ray structure was obtained and used to guide the evolution. In silico modelling and substrate docking provided some insight into the influence of several important amino acid mutations of the engineered P450pyr mutants on the altered or enhanced regio- and enantioselectivity as well as new substrate acceptance. The obtained information and knowledge is useful for further engineering of P450pyr for other hydroxylations and oxidations.

  8. Synthesis of Azide-Functionalized Hydroxyl-Terminated Polybutadiene

    NASA Astrophysics Data System (ADS)

    Shekhar Pant, Chandra; Santosh Mada, S. S. N. M.; Mehilal; Banerjee, Shaibal; Khanna, Pawan K.

    2016-10-01

    This article reports ways to functionalize hydroxyl-terminated polybutadiene (HTPB) by azide groups to impart energetic properties to the polymer. Two different synthetic approaches were explored to synthesize azide-functionalized hydroxyl-terminated polybutadiene (azide-HTPB). The functionalized polymer was analyzed for structural confirmation and determination of important physical and thermal properties. Azide-HTPB obtained by azidation of 10% double bonds of HTPB showed viscosity of 11 Pa.s and a glass transition temperature of -66°C.

  9. Dynamic regulation of Polycomb group activity during plant development.

    PubMed

    Bemer, Marian; Grossniklaus, Ueli

    2012-11-01

    Polycomb group (PcG) complexes play important roles in phase transitions and cell fate determination in plants and animals, by epigenetically repressing sets of genes that promote either proliferation or differentiation. The continuous differentiation of new organs in plants, such as leaves or flowers, requires a highly dynamic PcG function, which can be induced, modulated, or repressed when necessary. In this review, we discuss the recent advance in understanding PcG function in plants and focus on the diverse molecular mechanisms that have been described to regulate and counteract PcG activity in Arabidopsis.

  10. Dynamic regulation of Polycomb group activity during plant development.

    PubMed

    Bemer, Marian; Grossniklaus, Ueli

    2012-11-01

    Polycomb group (PcG) complexes play important roles in phase transitions and cell fate determination in plants and animals, by epigenetically repressing sets of genes that promote either proliferation or differentiation. The continuous differentiation of new organs in plants, such as leaves or flowers, requires a highly dynamic PcG function, which can be induced, modulated, or repressed when necessary. In this review, we discuss the recent advance in understanding PcG function in plants and focus on the diverse molecular mechanisms that have been described to regulate and counteract PcG activity in Arabidopsis. PMID:22999383

  11. Space station group activities habitability module study: A synopsis

    NASA Technical Reports Server (NTRS)

    Nixon, David; Glassman, Terry

    1987-01-01

    Space station habitability was studied by investigating crew activity routines, proximities, ergonomic envelopes, and group volumes. Ten alternative schematic interior designs were proposed. Preliminary conclusions include: (1) in-service interior modifications may be necessary and should be planned for; (2) design complexity will be increased if the module cluster is reduced from five to three; (3) the increased crew circulation attendant upon enhancement of space station activity may produce human traffic bottlenecks and should be planned for; (4) a single- or two-person quiet area may be desirable to provide crew members with needed solitude during waking hours; and (5) the decision to choose a two-shift or three-shift daily cycle will have a significant impact on the design configuration and operational efficiency of the human habitat.

  12. Activation of Human Complement System by Dextran-Coated Iron Oxide Nanoparticles Is Not Affected by Dextran/Fe Ratio, Hydroxyl Modifications, and Crosslinking

    PubMed Central

    Wang, Guankui; Chen, Fangfang; Banda, Nirmal K.; Holers, V. Michael; Wu, LinPing; Moghimi, S. Moein; Simberg, Dmitri

    2016-01-01

    While having tremendous potential as therapeutic and imaging tools, the clinical use of engineered nanoparticles has been associated with serious safety concerns. Activation of the complement cascade and the release of proinflammatory factors C3a and C5a may contribute to infusion-related reactions, whereas opsonization with C3 fragments promotes rapid recognition and clearance of nanomaterials by mononuclear phagocytes. We used dextran-coated superparamagnetic iron oxide nanoparticles (SPIO), which are potent activators of the complement system, to study the role of nanoparticle surface chemistry in inciting complement in human serum. Using complement inhibitors and measuring levels of fluid phase markers (sC5b-9, C5a, and Bb), we found that the majority of human complement activation by SPIO is through the alternative pathways (AP). SPIO prepared with high dextran/iron ratio showed some complement activation via calcium-sensitive pathways, but the AP was responsible for the bulk of complement activation and amplification. Activation via the AP required properdin, the positive regulator of the alternative C3bBb convertase. Modification of sugar alcohols of dextran with alkylating, acylating, or crosslinking agents did not overcome complement activation and C3 opsonization. These data demonstrate that human complement activation is independent of dextran modification of SPIO and suggest a crucial role of the AP in immune recognition of nano-assemblies in human serum. PMID:27777575

  13. Steroid Hydroxylation by Basidiomycete Peroxygenases: a Combined Experimental and Computational Study

    PubMed Central

    Babot, Esteban D.; del Río, José C.; Cañellas, Marina; Sancho, Ferran; Lucas, Fátima; Guallar, Víctor; Kalum, Lisbeth; Lund, Henrik; Gröbe, Glenn; Scheibner, Katrin; Ullrich, René; Hofrichter, Martin; Martínez, Angel T.

    2015-01-01

    The goal of this study is the selective oxyfunctionalization of steroids under mild and environmentally friendly conditions using fungal enzymes. With this purpose, peroxygenases from three basidiomycete species were tested for the hydroxylation of a variety of steroidal compounds, using H2O2 as the only cosubstrate. Two of them are wild-type enzymes from Agrocybe aegerita and Marasmius rotula, and the third one is a recombinant enzyme from Coprinopsis cinerea. The enzymatic reactions on free and esterified sterols, steroid hydrocarbons, and ketones were monitored by gas chromatography, and the products were identified by mass spectrometry. Hydroxylation at the side chain over the steroidal rings was preferred, with the 25-hydroxyderivatives predominating. Interestingly, antiviral and other biological activities of 25-hydroxycholesterol have been reported recently (M. Blanc et al., Immunity 38:106–118, 2013, http://dx.doi.org/10.1016/j.immuni.2012.11.004). However, hydroxylation in the ring moiety and terminal hydroxylation at the side chain also was observed in some steroids, the former favored by the absence of oxygenated groups at C-3 and by the presence of conjugated double bonds in the rings. To understand the yield and selectivity differences between the different steroids, a computational study was performed using Protein Energy Landscape Exploration (PELE) software for dynamic ligand diffusion. These simulations showed that the active-site geometry and hydrophobicity favors the entrance of the steroid side chain, while the entrance of the ring is energetically penalized. Also, a direct correlation between the conversion rate and the side chain entrance ratio could be established that explains the various reaction yields observed. PMID:25862224

  14. Niacin activates the PI3K/Akt cascade via PKC- and EGFR-transactivation-dependent pathways through hydroxyl-carboxylic acid receptor 2.

    PubMed

    Sun, Huawang; Li, Guo; Zhang, Wenjuan; Zhou, Qi; Yu, Yena; Shi, Ying; Offermanns, Stefan; Lu, Jianxin; Zhou, Naiming

    2014-01-01

    Niacin has been demonstrated to activate a PI3K/Akt signaling cascade to prevent brain damage after stroke and UV-induced skin damage; however, the underlying molecular mechanisms for HCA2-induced Akt activation remain to be elucidated. Using CHO-K1 cells stably expressing HCA2 and A431 cells, a human epidermoid cell line with high levels of endogenous expression of functional HCA2 receptors, we first demonstrated that niacin induced a robust Akt phosphorylation at both Thr308 and Ser473 in a time-dependent fashion, with a maximal activation at 5 min and a subsequent reduction to baseline by 30 min through HCA2, and that the activation was significantly blocked by pertussis toxin. The HCA2-mediated activation of Akt was also significantly inhibited by the PKC inhibitors GF109203x and Go6983 in both cell lines, by the PDGFR-selective inhibitor tyrphostin A9 in CHO-HCA2 cells and by the MMP inhibitor GM6001 and EGFR-specific inhibitor AG1478 in A431 cells. These results suggest that the PKC pathway and PDGFR/EGFR transactivation pathway play important roles in HCA2-mediated Akt activation. Further investigation indicated that PI3K and the Gβγ subunit were likely to play an essential role in HCA2-induced Akt activation. Moreover, Immunobloting analyses using an antibody that recognizes p70S6K1 phosphorylated at Thr389 showed that niacin evoked p70S6K1 activation via the PI3K/Akt pathway. The results of our study provide new insight into the signaling pathways involved in HCA2 activation.

  15. Ab initio dynamics of the cytochrome P450 hydroxylation reaction

    SciTech Connect

    Elenewski, Justin E.; Hackett, John C

    2015-02-14

    The iron(IV)-oxo porphyrin π-cation radical known as Compound I is the primary oxidant within the cytochromes P450, allowing these enzymes to affect the substrate hydroxylation. In the course of this reaction, a hydrogen atom is abstracted from the substrate to generate hydroxyiron(IV) porphyrin and a substrate-centered radical. The hydroxy radical then rebounds from the iron to the substrate, yielding the hydroxylated product. While Compound I has succumbed to theoretical and spectroscopic characterization, the associated hydroxyiron species is elusive as a consequence of its very short lifetime, for which there are no quantitative estimates. To ascertain the physical mechanism underlying substrate hydroxylation and probe this timescale, ab initio molecular dynamics simulations and free energy calculations are performed for a model of Compound I catalysis. Semiclassical estimates based on these calculations reveal the hydrogen atom abstraction step to be extremely fast, kinetically comparable to enzymes such as carbonic anhydrase. Using an ensemble of ab initio simulations, the resultant hydroxyiron species is found to have a similarly short lifetime, ranging between 300 fs and 3600 fs, putatively depending on the enzyme active site architecture. The addition of tunneling corrections to these rates suggests a strong contribution from nuclear quantum effects, which should accelerate every step of substrate hydroxylation by an order of magnitude. These observations have strong implications for the detection of individual hydroxylation intermediates during P450 catalysis.

  16. Environmental distribution, abundance and activity of the Miscellaneous Crenarchaeotal Group

    NASA Astrophysics Data System (ADS)

    Lloyd, K. G.; Biddle, J.; Teske, A.

    2011-12-01

    Many marine sedimentary microbes have only been identified by 16S rRNA sequences. Consequently, little is known about the types of metabolism, activity levels, or relative abundance of these groups in marine sediments. We found that one of these uncultured groups, called the Miscellaneous Crenarchaeotal Group (MCG), dominated clone libraries made from reverse transcribed 16S rRNA, and 454 pyrosequenced 16S rRNA genes, in the White Oak River estuary. Primers suitable for quantitative PCR were developed for MCG and used to show that 16S rRNA DNA copy numbers from MCG account for nearly all the archaeal 16S rRNA genes present. RT-qPCR shows much less MCG rRNA than total archaeal rRNA, but comparisons of different primers for each group suggest bias in the RNA-based work relative to the DNA-based work. There is no evidence of a population shift with depth below the sulfate-methane transition zone, suggesting that the metabolism of MCG may not be tied to sulfur or methane cycles. We classified 2,771 new sequences within the SSU Silva 106 database that, along with the classified sequences in the Silva database was used to make an MCG database of 4,646 sequences that allowed us to increase the named subgroups of MCG from 7 to 19. Percent terrestrial sequences in each subgroup is positively correlated with percent of the marine sequences that are nearshore, suggesting that membership in the different subgroups is not random, but dictated by environmental selective pressures. Given their high phylogenetic diversity, ubiquitous distribution in anoxic environments, and high DNA copy number relative to total archaea, members of MCG are most likely anaerobic heterotrophs who are integral to the post-depositional marine carbon cycle.

  17. Hydroxyl radical induced degradation of ibuprofen.

    PubMed

    Illés, Erzsébet; Takács, Erzsébet; Dombi, András; Gajda-Schrantz, Krisztina; Rácz, Gergely; Gonter, Katalin; Wojnárovits, László

    2013-03-01

    Pulse radiolysis experiments were used to characterize the intermediates formed from ibuprofen during electron beam irradiation in a solution of 0.1mmoldm(-3). For end product characterization (60)Co γ-irradiation was used and the samples were evaluated either by taking their UV-vis spectra or by HPLC with UV or MS detection. The reactions of OH resulted in hydroxycyclohexadienyl type radical intermediates. The intermediates produced in further reactions hydroxylated the derivatives of ibuprofen as final products. The hydrated electron attacked the carboxyl group. Ibuprofen degradation is more efficient under oxidative conditions than under reductive conditions. The ecotoxicity of the solution was monitored by Daphnia magna standard microbiotest and Vibrio fischeri luminescent bacteria test. The toxic effect of the aerated ibuprofen solution first increased upon irradiation indicating a higher toxicity of the first degradation products, then decreased with increasing absorbed dose.

  18. Lincomycin Biosynthesis Involves a Tyrosine Hydroxylating Heme Protein of an Unusual Enzyme Family

    PubMed Central

    Novotna, Jitka; Olsovska, Jana; Novak, Petr; Mojzes, Peter; Chaloupkova, Radka; Kamenik, Zdenek; Spizek, Jaroslav; Kutejova, Eva; Mareckova, Marketa; Tichy, Pavel; Damborsky, Jiri; Janata, Jiri

    2013-01-01

    The gene lmbB2 of the lincomycin biosynthetic gene cluster of Streptomyces lincolnensis ATCC 25466 was shown to code for an unusual tyrosine hydroxylating enzyme involved in the biosynthetic pathway of this clinically important antibiotic. LmbB2 was expressed in Escherichia coli, purified near to homogeneity and shown to convert tyrosine to 3,4-dihydroxyphenylalanine (DOPA). In contrast to the well-known tyrosine hydroxylases (EC 1.14.16.2) and tyrosinases (EC 1.14.18.1), LmbB2 was identified as a heme protein. Mass spectrometry and Soret band-excited Raman spectroscopy of LmbB2 showed that LmbB2 contains heme b as prosthetic group. The CO-reduced differential absorption spectra of LmbB2 showed that the coordination of Fe was different from that of cytochrome P450 enzymes. LmbB2 exhibits sequence similarity to Orf13 of the anthramycin biosynthetic gene cluster, which has recently been classified as a heme peroxidase. Tyrosine hydroxylating activity of LmbB2 yielding DOPA in the presence of (6R)-5,6,7,8-tetrahydro-L-biopterin (BH4) was also observed. Reaction mechanism of this unique heme peroxidases family is discussed. Also, tyrosine hydroxylation was confirmed as the first step of the amino acid branch of the lincomycin biosynthesis. PMID:24324587

  19. Biologically Active Acetylenic Amino Alcohol and N-Hydroxylated 1,2,3,4-Tetrahydro-β-carboline Constituents of the New Zealand Ascidian Pseudodistoma opacum.

    PubMed

    Wang, Jiayi; Pearce, A Norrie; Chan, Susanna T S; Taylor, Richard B; Page, Michael J; Valentin, Alexis; Bourguet-Kondracki, Marie-Lise; Dalton, James P; Wiles, Siouxsie; Copp, Brent R

    2016-03-25

    The first occurrence of an acetylenic 1-amino-2-alcohol, distaminolyne A (1), isolated from the New Zealand ascidian Pseudodistoma opacum, is reported. The isolation and structure elucidation of 1 and assignment of absolute configuration using the exciton coupled circular dichroism technique are described. In addition, a new N-9 hydroxy analogue (2) of the known P. opacum metabolite 7-bromohomotrypargine is also reported. Antimicrobial screening identified modest activity of 1 toward Escherichia coli, Staphylococcus aureus, and Mycobacterim tuberculosis, while 2 exhibited a moderate antimalarial activity (IC50 3.82 μM) toward a chloroquine-resistant strain (FcB1) of Plasmodium falciparum. PMID:26670413

  20. Hydroxylation and dealkylation reactions catalyzed by hemoglobin.

    PubMed

    Mieyal, J J; Starke, D W

    1994-01-01

    Red blood cells contain many enzymes that are akin to those that catalyze xenobiotic metabolism in liver and other tissues. An obvious exception is the cytochrome P-450 system that is found in virtually all other tissues. In vitro studies, however, have shown that hemoglobin can be a broad monooxygenase catalyst, exhibiting the properties of a monooxygenase enzyme. Thus, catalysis by Hb displays typical Michaelis-Menten kinetics, dependence on the native protein, coupling to NADPH-dependent flavoprotein reductases, and inhibition by carbon monoxide. The reconstituted system containing Hb along with P-450 reductase utilizes NADPH and O2 to catalyze typical monooxygenase reactions, including O- and N-demethylations as well as aromatic and aliphatic hydroxylations, and the catalytic cycle appears to mimic the typical P-450 mechanism. Turnover numbers for aniline hydroxylation are similar for Hb and P-450 reconstituted systems, whereas P-450 systems are more effective for other reactions. Catalysis by Hb seems to be restricted to the beta-heme sites of the tetramer, reflecting more facile substrate access. Overall the similarities and differences between Hb and P-450 provide an opportunity to examine the basis for their differential monooxygenase or peroxidase/peroxygenase activities in a comparative manner. Hb may be especially useful in delineating the early events in the respective reaction schemes, because it can be studied in various stable redox/ligand states, including the oxyferrous form. Similar hemoglobin-catalyzed oxidative biotransformations occur within intact erythrocytes, but apparent turnover numbers are much lower than those with the reconstituted Hb system, suggesting different mechanisms of catalysis. Although Hb-mediated oxidase activity in erythrocytes is low relative to other sites of xenobiotic metabolism, it may contribute to in situ activation of xenobiotics leading to oxidative stress, disruption of sulfhydryl homeostasis in the erythrocytes

  1. Phase I Hydroxylated Metabolites of the K2 Synthetic Cannabinoid JWH-018 Retain In Vitro and In Vivo Cannabinoid 1 Receptor Affinity and Activity

    PubMed Central

    Brents, Lisa K.; Reichard, Emily E.; Zimmerman, Sarah M.; Moran, Jeffery H.; Fantegrossi, William E.; Prather, Paul L.

    2011-01-01

    Background K2 products are synthetic cannabinoid-laced, marijuana-like drugs of abuse, use of which is often associated with clinical symptoms atypical of marijuana use, including hypertension, agitation, hallucinations, psychosis, seizures and panic attacks. JWH-018, a prevalent K2 synthetic cannabinoid, is structurally distinct from Δ9-THC, the main psychoactive ingredient in marijuana. Since even subtle structural differences can lead to differential metabolism, formation of novel, biologically active metabolites may be responsible for the distinct effects associated with K2 use. The present study proposes that K2's high adverse effect occurrence is due, at least in part, to distinct JWH-018 metabolite activity at the cannabinoid 1 receptor (CB1R). Methods/Principal Findings JWH-018, five potential monohydroxylated metabolites (M1–M5), and one carboxy metabolite (M6) were examined in mouse brain homogenates containing CB1Rs, first for CB1R affinity using a competition binding assay employing the cannabinoid receptor radioligand [3H]CP-55,940, and then for CB1R intrinsic efficacy using an [35S]GTPγS binding assay. JWH-018 and M1–M5 bound CB1Rs with high affinity, exhibiting Ki values that were lower than or equivalent to Δ9-THC. These molecules also stimulated G-proteins with equal or greater efficacy relative to Δ9-THC, a CB1R partial agonist. Most importantly, JWH-018, M2, M3, and M5 produced full CB1R agonist levels of activation. CB1R-mediated activation was demonstrated by blockade with O-2050, a CB1R-selective neutral antagonist. Similar to Δ9-THC, JWH-018 and M1 produced a marked depression of locomotor activity and core body temperature in mice that were both blocked by the CB1R-preferring antagonist/inverse agonist AM251. Conclusions/Significance Unlike metabolites of most drugs, the studied JWH-018 monohydroxylated compounds, but not the carboxy metabolite, retain in vitro and in vivo activity at CB1Rs. These observations, combined with higher

  2. Activities of the IERS Working Group on prediction

    NASA Astrophysics Data System (ADS)

    Wooden, W.

    2008-04-01

    The International Earth Rotation and Reference Systems Service (IERS) established a Working Group on Prediction (WGP) to investigate what IERS prediction products are useful to the user community in addition to making a detailed examination of the fundamental properties of the different input data sets and algorithms. The major goals and objectives of the WGP are to determine the desired Earth orientation prediction products, the importance of observational accuracy, which types of input data provide an optimal prediction, the strengths and weaknesses of various prediction algorithms, and the interactions between series and algorithms that are beneficial or harmful. To focus the research efforts of the WGP, the user community was polled to ascertain what prediction products are needed and at what level of accuracy. The current status of WGP activities and the anticipated future directions are presented.

  3. Photovoltaic Reliability Group activities in USA and Brazil (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Dhere, Neelkanth G.; Cruz, Leila R. O.

    2015-09-01

    Recently prices of photovoltaic (PV) systems have been reduced considerably and may continue to be reduced making them attractive. If these systems provide electricity over the stipulated warranty period, it would be possible attain socket parity within the next few years. Current photovoltaic module qualifications tests help in minimizing infant mortality but do not guarantee useful lifetime over the warranty period. The PV Module Quality Assurance Task Force (PVQAT) is trying to formulate accelerated tests that will be useful towards achieving the ultimate goal of assuring useful lifetime over the warranty period as well as to assure manufacturing quality. Unfortunately, assuring the manufacturing quality may require 24/7 presence. Alternatively, collecting data on the performance of fielded systems would assist in assuring manufacturing quality. Here PV systems installed by home-owners and small businesses can constitute as an important untapped source of data. The volunteer group, PV - Reliable, Safe and Sustainable Quality! (PVRessQ!) is providing valuable service to small PV system owners. Photovoltaic Reliability Group (PVRG) is initiating activities in USA and Brazil to assist home owners and small businesses in monitoring photovoltaic (PV) module performance and enforcing warranty. It will work in collaboration with small PV system owners, consumer protection agencies. Brazil is endowed with excellent solar irradiance making it attractive for installation of PV systems. Participating owners of small PV systems would instruct inverter manufacturers to copy the daily e-mails to PVRG and as necessary, will authorize the PVRG to carry out review of PV systems. The presentation will consist of overall activities of PVRG in USA and Brazil.

  4. Inhibitory effects of hydroxylated cinnamoyl esters on lipid absorption and accumulation.

    PubMed

    Imai, Masahiko; Kumaoka, Takaya; Hosaka, Makiko; Sato, Yui; Li, Chuan; Sudoh, Masashi; Tamada, Yoshiko; Yokoe, Hiromasa; Saito, Setsu; Tsubuki, Masayoshi; Takahashi, Noriko

    2015-07-01

    Obesity is a risk factor associated with several lifestyle-related diseases, for example, diabetes, high blood pressure, hyperlipidemia and cancer. Caffeic acid 2-phenylethyl ester (CAPE, 1), a naturally-occurring compound found in various plants and propolis, which exhibits anti-inflammatory, immunomodulatory and cytotoxic activities and inhibits 3T3-L1 differentiation to adipocytes. As part of our efforts to moderate lifestyle-related diseases, we synthesized analogs of 1 and studied their effects on pancreatic lipase activities, lipid absorption, and 3T3-L1 differentiation. We found that catechols 1-4 show inhibitory activities against pancreatic lipase in a dose-dependent manner in vitro. Compounds 1-3 proved to be more potent inhibitors of pancreatic lipase than 5, 6, 8, and 9, which have one hydroxyl group, respectively. Compound 7 has three aromatic hydroxyl groups and restrains greater lipase inhibitory activity than the other compounds. In addition, 7 and 3 significantly suppress a rise in blood triglyceride (TG) levels in mice given corn oil orally. Furthermore, 2 and 3 are more potent at preventing 3T3-L1 differentiation (lipid accumulation) than 1, while 7 is more potent than 3, 8, and 9 in these assays. Compounds 2, 3, and 7 inhibit lipid absorption and accumulation, with new compound 7 being the most potent. These results indicate that 7 may have potential benefits as a health agent with anti-obesity properties. PMID:25910587

  5. Structure-Activity Relationship of Selected Meta- and Para-Hydroxylated Non–Dioxin Like Polychlorinated Biphenyls: From Single RyR1 Channels to Muscle Dysfunction

    PubMed Central

    Pessah, Isaac N.

    2013-01-01

    Non–dioxin like polychlorinated biphenyls (NDL-PCBs) are legacy environmental contaminants with contemporary unintentional sources. NDL-PCBs interact with ryanodine receptors (RyRs), Ca2+ channels of sarcoplasmic/endoplasmic reticulum (SR/ER) that regulate excitation-contraction coupling (ECC) and Ca2+-dependent cell signaling in muscle. Activities of 4 chiral congeners PCB91, 95, 132, and 149 and their respective 4- and 5-hydroxy (-OH) derivatives toward rabbit skeletal muscle ryanodine receptor (RyR1) are investigated using [3H]ryanodine binding and SR Ca2+ flux analyses. Although 5-OH metabolites have comparable activity to their respective parent in both assays, 4-OH derivatives are unable to trigger Ca2+ release from SR microsomes in the presence of Ca2+-ATPase activity. PCB95 and derivatives are investigated using single channel voltage-clamp and primary murine embryonic muscle cells (myotubes). Like PCB95, 5-OH-PCB95 quickly and persistently increases channel open probability (p o > .9) by stabilizing the full-open channel state, whereas 4-OH-PCB95 transiently enhances p o. Ca2+ imaging of myotubes loaded with Fluo-4 show that acute exposure to PCB95 (5µM) potentiates ECC and caffeine responses and partially depletes SR Ca2+ stores. Exposure to 5-OH-PCB95 (5 µM) increases cytoplasmic Ca2+, leading to rapid ECC failure in 50% of myotubes with the remainder retaining negligible responses. 4-OH-PCB95 neither increases baseline Ca2+ nor causes ECC failure but depresses ECC and caffeine responses by 50%. With longer (3h) exposure to 300nM PCB95, 5-OH-PCB95, or 4-OH-PCB95 decreases the number of ECC responsive myotubes by 22%, 81%, and 51% compared with control by depleting SR Ca2+ and/or uncoupling ECC. NDL-PCBs and their 5-OH and 4-OH metabolites differentially influence RyR1 channel activity and ECC in embryonic skeletal muscle. PMID:24014653

  6. Determination of hydroxylated thiophenic compounds in a coal liquid

    SciTech Connect

    Nishioka, M.; Lee, M.L.; Kudo, H.; Muchiri, D.R.; Baldwin, L.J.; Pakray, S.; Stuart, J.G.; Castle, R.N.

    1985-06-01

    Hydroxylated thiophenic compounds in a coal liquid were determined by capillary column gas chromatography and gas chromatography/mass spectrometry. Capillary column gas chromatography with two new selective stationary phases, a biphenyl polysiloxane and a smectic liquid crystalline poly-siloxane, were used. Several compounds were positively identified by comparison of their retention times with those of newly synthesized standard compounds. Sulfur-selective flame photometric detection and mass spectrometry were used to verify compound identifications. Two groupings of hydroxylated thiophenic compounds were observed in this sample. The first group is composed of hydroxybenzo-thiophenes and (hydroxyphenyl)thiophenes, while the second group contains hydroxydibenzothiophenes and (hydroxyphenyl)benzothiophenes. 22 references, 2 figures, 1 table.

  7. Hydroxylated chalcones with dual properties: Xanthine oxidase inhibitors and radical scavengers.

    PubMed

    Hofmann, Emily; Webster, Jonathan; Do, Thuy; Kline, Reid; Snider, Lindsey; Hauser, Quintin; Higginbottom, Grace; Campbell, Austin; Ma, Lili; Paula, Stefan

    2016-02-15

    In this study, we evaluated the abilities of a series of chalcones to inhibit the activity of the enzyme xanthine oxidase (XO) and to scavenge radicals. 20 mono- and polyhydroxylated chalcone derivatives were synthesized by Claisen-Schmidt condensation reactions and then tested for inhibitory potency against XO, a known generator of reactive oxygen species (ROS). In parallel, the ability of the synthesized chalcones to scavenge a stable radical was determined. Structure-activity relationship analysis in conjunction with molecular docking indicated that the most active XO inhibitors carried a minimum of three hydroxyl groups. Moreover, the most effective radical scavengers had two neighboring hydroxyl groups on at least one of the two phenyl rings. Since it has been proposed previously that XO inhibition and radical scavenging could be useful properties for reduction of ROS-levels in tissue, we determined the chalcones' effects to rescue neurons subjected to ROS-induced stress created by the addition of β-amyloid peptide. Best protection was provided by chalcones that combined good inhibitory potency with high radical scavenging ability in a single molecule, an observation that points to a potential therapeutic value of this compound class.

  8. Activities of the EMRAS Tritium/C14 Working Group

    SciTech Connect

    Davis, P.A.; Balonov, M.; Venter, A

    2005-07-15

    A new model evaluation program, Environmental Modeling for Radiation Safety (EMRAS), was initiated by the International Atomic Energy Agency in September 2003. EMRAS includes a working group (WG) on modeling tritium and C-14 transfer through the environment to biota and man. The main objective of this WG is to develop and test models of the uptake, formation and translocation of organically bound tritium (OBT) in food crops, animals and aquatic systems. To the extent possible, the WG is carrying out its work by comparing model predictions with experimental data to identify the modeling approaches and assumptions that lead to the best agreement between predictions and observations. Results for scenarios involving a chronically contaminated aquatic ecosystem and short-term exposure of soybeans are presently being analyzed. In addition, calculations for scenarios involving chronically contaminated terrestrial food chains and hypothetical short-term releases are currently underway, and a pinetree scenario is being developed. The preparation of datasets on tritium dynamics in large animals and fish is being encouraged, since these are the areas of greatest uncertainty in OBT modeling. These activities will be discussed in this paper.

  9. Update on Activities of CEOS Disaster Management Support Group

    NASA Astrophysics Data System (ADS)

    Wood, H. M.; Lauritson, L.

    The Committee on Earth Observation Satellites (CEOS) Disaster Management Support Group (DMSG) has supported natural and technological disaster management on a worldwide basis by fostering improved utilization of existing and planned Earth Observation (EO) satellite data. The DMSG has focused on developing and refining recommendations for the application of satellite data to selected hazard areas--drought, earthquake, fire, flood, ice, landslide, oil spill, and volcanic hazards. Particular emphasis was placed on working closely with space agencies, international and regional organizations, and commercial organizations on the implementation of these recommendations. The DMSG is in its last year with its primary focus on documenting its work and migrating on going activities to other fora. With over 300 participants from more than 140 organizations, the DMSG has found strong support among CEOS space agencies and the Integrated Global Observing Strategy (IGOS), as well as an enthusiastic reception from numerous international, regional, and national emergency managers, and distinct interest from the commercial sector. In addition, the group has worked to give full support to the work of the United Nations Committee on the Peaceful Uses of Outer Space (COPUOS) in pursuit of decisions taken at UNISPACE III and the United Nations International Strategy on Disaster Reduction (ISDR). In conjunction with the IGOS, several of the DMSG hazards teams (earthquake, landslide, and solid Earth dimensions of volcanoes) are joining in the effort to develop an IGOS Geohazards theme team. Cooperation efforts with organizations such as IGOS, COPUOS, and ISDR will hopefully lead to the pick up of much of the on going DMSG activities. Since the inception of this ad hoc working group and its predecessor project, the DMSG has developed and refined recommendations for the application of satellite data by bringing together experts from eight hazard areas to identify user needs, as well as

  10. Creation of localized spins in graphene by ring-opening of epoxy derived hydroxyl.

    PubMed

    Chen, Jie; Zhang, Weili; Sun, Yuanyuan; Zheng, Yongping; Tang, Nujiang; Du, Youwei

    2016-05-26

    Creation of high-density localized spins in the basal plane of graphene sheet by introduction of sp(3)-type defects is considered to be a potential route for the realization of high-magnetization graphene. Theoretical and experimental studies confirmed that hydroxyl can be an effective sp(3)-type candidate for inducing robust magnetic moment. However, the artificial generation of hydroxyl groups for creating high-density spins on the basal plane of graphene sheet is very scarce. Here we demonstrate that high-content hydroxyl groups can be generated on the basal plane of graphene oxide (GO) sheet by ring opening of epoxy groups. We show that by introduction of 10.74 at.% hydroxyl groups, the density of localized spins of GO can be significantly increased from 0.4 to 5.17 μB/1000 C. Thus, this study provided an effective method to obtain graphene with high-density localized spins.

  11. Creation of localized spins in graphene by ring-opening of epoxy derived hydroxyl

    PubMed Central

    Chen, Jie; Zhang, Weili; Sun, Yuanyuan; Zheng, Yongping; Tang, Nujiang; Du, Youwei

    2016-01-01

    Creation of high-density localized spins in the basal plane of graphene sheet by introduction of sp3-type defects is considered to be a potential route for the realization of high-magnetization graphene. Theoretical and experimental studies confirmed that hydroxyl can be an effective sp3-type candidate for inducing robust magnetic moment. However, the artificial generation of hydroxyl groups for creating high-density spins on the basal plane of graphene sheet is very scarce. Here we demonstrate that high-content hydroxyl groups can be generated on the basal plane of graphene oxide (GO) sheet by ring opening of epoxy groups. We show that by introduction of 10.74 at.% hydroxyl groups, the density of localized spins of GO can be significantly increased from 0.4 to 5.17 μB/1000 C. Thus, this study provided an effective method to obtain graphene with high-density localized spins. PMID:27225991

  12. Hydroxylation of a metal-supported hexagonal boron nitride monolayer by oxygen induced water dissociation.

    PubMed

    Guo, Yufeng; Guo, Wanlin

    2015-07-01

    Hydroxylated hexagonal boron nitride (h-BN) nanosheets exhibit potential application in nanocomposites and functional surface coating. Our first-principles calculations reveal possible hydroxylation of a h-BN monolayer on a Ni substrate by surface O adatom induced spontaneous dissociation of water molecules. Here one H atom is split from a water molecule by bonding with the O adatom on the B atom and the resulting O-H radical then bonds with an adjacent B atom, which leads to two hydroxyl groups formed on h-BN/Ni. Hydroxylation slightly influences the electronic properties of a Ni-supported h-BN layer. Similar water dissociation and hydroxylation can occur on the surface of O functionalized h-BN/Cu depending on the O adsorption configuration. Metal substrates play an important catalytic role in enhancing the chemical reactivity of O adatoms on h-BN with water molecules through transferring additional charges to them. PMID:26051363

  13. Incorporating More Individual Accountability in Group Activities in General Chemistry

    ERIC Educational Resources Information Center

    Cox, Charles T., Jr.

    2015-01-01

    A modified model of cooperative learning known as the GIG model (for group-individual-group) designed and implemented in a large enrollment freshman chemistry course. The goal of the model is to establish a cooperative environment while emphasizing greater individual accountability using both group and individual assignments. The assignments were…

  14. Some Factors Relevant to Group Activities in Language Teaching

    ERIC Educational Resources Information Center

    Mugglestone, Patricia

    1975-01-01

    Discusses the handling of groups. The teacher should be aware of variables: size of group, composition (by ability, needs, etc.), seating arrangement, group structure, etc. Cooperative, competitive or individual work should be used, depending on the learning goal. The teacher must be perceptive, flexible, and must have good organizing ability.…

  15. Quantity, Quality, and Variety of Pupil Responses during an Open-Communication Structured Group Directed Reading-Thinking Activity and a Closed Communication Structured Group Directed Reading Activity.

    ERIC Educational Resources Information Center

    Petre, Richard M.

    The quality, quantity, and variety of pupil responses while using two different group directed reading activities, the Directed Reading Activity (DRA), and the Directed Reading-Thinking Activity (DRTA) were investigated in this study. The subjects, all fourth graders in two nearby communities, were grouped into above-grade-level, at-grade-level,…

  16. Fum3p, a 2-ketoglutarate-dependent dioxygenase required for C-5 hydroxylation of fumonisins in Fusarium verticillioides.

    PubMed

    Ding, Yousong; Bojja, Ravi S; Du, Liangcheng

    2004-04-01

    Fumonisins are polyketide-derived mycotoxins produced by several agriculturally important Fusarium species. The B series fumonisins, FB(1), FB(2), FB(3), and FB(4), are fumonisins produced by wild-type Fusarium verticillioides strains, differing in the number and location of hydroxyl groups attached to the carbon backbone. We characterized the protein encoded by FUM3, a gene in the fumonisin biosynthetic gene cluster. The 33-kDa FUM3 protein (Fum3p) was heterologously expressed and purified from Saccharomyces cerevisiae. Yeast cells expressing the Fum3p converted FB(3) to FB(1), indicating that Fum3p catalyzes the C-5 hydroxylation of fumonisins. This result was verified by assaying the activity of Fum3p purified from yeast cells. The C-5 hydroxylase activity of purified Fum3p required 2-ketoglutarate, Fe(2+), ascorbic acid, and catalase, all of which are required for 2-ketoglutarate-dependent dioxygenases. The protein also contains two His motifs that are highly conserved in this family of dioxygenases. Thus, Fum3p is a 2-ketoglutarate-dependent dioxygenase required for the addition of the C-5 hydroxyl group of fumonisins.

  17. Monkey liver cytochrome P450 2C19 is involved in R- and S-warfarin 7-hydroxylation.

    PubMed

    Hosoi, Yoshio; Uno, Yasuhiro; Murayama, Norie; Fujino, Hideki; Shukuya, Mitsunori; Iwasaki, Kazuhide; Shimizu, Makiko; Utoh, Masahiro; Yamazaki, Hiroshi

    2012-12-15

    Cynomolgus monkeys are widely used as primate models in preclinical studies. However, some differences are occasionally seen between monkeys and humans in the activities of cytochrome P450 enzymes. R- and S-warfarin are model substrates for stereoselective oxidation in humans. In this current research, the activities of monkey liver microsomes and 14 recombinantly expressed monkey cytochrome P450 enzymes were analyzed with respect to R- and S-warfarin 6- and 7-hydroxylation. Monkey liver microsomes efficiently mediated both R- and S-warfarin 7-hydroxylation, in contrast to human liver microsomes, which preferentially catalyzed S-warfarin 7-hydroxylation. R-Warfarin 7-hydroxylation activities in monkey liver microsomes were not inhibited by α-naphthoflavone or ketoconazole, and were roughly correlated with P450 2C19 levels and flurbiprofen 4-hydroxylation activities in microsomes from 20 monkey livers. In contrast, S-warfarin 7-hydroxylation activities were not correlated with the four marker drug oxidation activities used. Among the 14 recombinantly expressed monkey P450 enzymes tested, P450 2C19 had the highest activities for R- and S-warfarin 7-hydroxylations. Monkey P450 3A4 and 3A5 slowly mediated R- and S-warfarin 6-hydroxylations. Kinetic analysis revealed that monkey P450 2C19 had high V(max) and low K(m) values for R-warfarin 7-hydroxylation, comparable to those for monkey liver microsomes. Monkey P450 2C19 also mediated S-warfarin 7-hydroxylation with V(max) and V(max)/K(m) values comparable to those for recombinant human P450 2C9. R-warfarin could dock favorably into monkey P450 2C19 modeled. These results collectively suggest high activities for monkey liver P450 2C19 toward R- and S-warfarin 6- and 7-hydroxylation in contrast to the saturation kinetics of human P450 2C9-mediated S-warfarin 7-hydroxylation.

  18. Space Weather Activities of IONOLAB Group: IONOLAB-TEC

    NASA Astrophysics Data System (ADS)

    Arikan, F.; Sezen, U.; Arikan, O.; Ugurlu, O.; Nayir, H.

    2009-04-01

    Space Weather (SW) is the concept of changing environmental conditions in outer space and affect Earth and its technological systems. SW is a consequence of the solar activities and the coupling of solar energy on Earth's atmosphere due to the Earth's magnetic field. The monitoring and prediction of SW has utmost importance for HF communication, Satellite communication, navigation and guidance systems, Low Earth Orbit (LEO) satellite systems, Space Craft exit and entry into the atmosphere. Ionosphere is the plasma layer of the atmosphere that is ionized by solar radiation and it is a key player of SW. Ionosphere is a temporally and spatially varying, dispersive, anisotropic and inhomogeneous medium that is characterized primarily by its electron density distribution. IONOLAB is a group of researchers of various disciplines, getting together to handle challenges of the Earth's ionosphere. The team has researchers from Hacettepe University and Bilkent University, Department of Electrical and Electronics Engineering and General Command of Mapping of Turkish Army. One of the most important contributions of IONOLAB group is the automated web-based computation service for Total Electron Content (TEC). TEC corresponds to the line integral of electron density distribution on a given path. TEC can also be expressed as the amount of free electrons within 1 m2 cross-sectional area of the cylinder on the ray path. Global Position System (GPS) provides a cost-effective medium for monitoring of ionosphere using the signals recorded by stationary GPS receivers in estimating TEC. IONOLAB group has developed IONOLAB-TEC for reliable and robust estimates for all latitudes and both calm and disturbed days by using RINEX, IONEX and satellite ephemeris data provided from the IGS centers. IONOLAB-TEC consists of a regularized signal estimation algorithm which combines signals from all GPS satellites for a given instant and a given receiver, for a desired time period or for 24 hours

  19. The Use of a Group Blog to Actively Support Learning Activities

    ERIC Educational Resources Information Center

    Duarte, Paulo

    2015-01-01

    Despite the widespread use of blogs in higher education, there remains a lack of knowledge and consensus about the use and value of blogging in higher education, particularly when used for long periods. This article investigates the use of a group blog to assist traditional teaching activities and foster collaborative learning through the…

  20. A Rearrangement of the Guanosine-Binding Site Establishes an Extended Network of Functional Interactions in the Tetrahymena Group I Ribozyme Active Site†

    PubMed Central

    Forconi, Marcello; Sengupta, Raghuvir N.; Piccirilli, Joseph A.; Herschlag, Daniel

    2010-01-01

    Protein enzymes appear to use extensive packing and hydrogen-bonding interactions to precisely position catalytic groups within active sites. Due to their inherent backbone flexibility and limited side chain repertoire, RNA enzymes face additional challenges relative to proteins in precisely positioning substrates and catalytic groups. Here, we use the group I ribozyme to probe the existence, establishment, and functional consequences of an extended network of interactions in an RNA active site. The group I ribozyme catalyzes a site-specific attack of guanosine on an oligonucleotide substrate. We previously determined that the hydrogen bond between the exocyclic amino group of guanosine and the 2′-hydroxyl group at position A261 of the Tetrahymena group I ribozyme contributes to overall catalysis. We now use functional data, aided by double-mutant cycles, to probe this hydrogen bond in the individual reaction steps of the catalytic cycle. Our results indicate that this hydrogen bond is not formed upon guanosine binding to the ribozyme but instead forms at a later stage of the catalytic cycle. Formation of this hydrogen bond is correlated to other structural rearrangements in the ribozyme's active site that are promoted by docking of the oligonucleotide substrate into the ribozyme's active site, and disruption of this interaction has deleterious consequences for the chemical transformation within the ternary complex. These results, combined with earlier results, provide insight into the nature of the multiple conformational steps used by the Tetrahymena group I ribozyme to achieve its active structure and reveal an intricate, extended network of interactions that is used to establish catalytic interactions within this RNA's active site. PMID:20175542

  1. Sulfur Dioxide Capture by Heterogeneous Oxidation on Hydroxylated Manganese Dioxide.

    PubMed

    Wu, Haodong; Cai, Weimin; Long, Mingce; Wang, Hairui; Wang, Zhiping; Chen, Chen; Hu, Xiaofang; Yu, Xiaojuan

    2016-06-01

    Here we demonstrate that sulfur dioxide (SO2) is efficiently captured via heterogeneous oxidation into sulfate on the surface of hydroxylated manganese dioxide (MnO2). Lab-scale activity tests in a fluidized bed reactor showed that the removal efficiency for a simulated flue gas containing 5000 mg·Nm(-3) SO2 could reach nearly 100% with a GHSV (gas hourly space velocity) of 10000 h(-1). The mechanism was investigated using a combination of experimental characterizations and theoretical calculations. It was found that formation of surface bound sulfate proceeds via association of SO2 with terminal hydroxyls. Both H2O and O2 are essential for the generation of reactive terminal hydroxyls, and the indirect role of O2 in heterogeneous SO2 oxidation at low temperature was also revealed. We propose that the high reactivity of terminal hydroxyls is attributed to the proper surface configuration of MnO2 to adsorb water with degenerate energies for associative and dissociative states, and maintain rapid proton dynamics. Viability analyses suggest that the desulfurization method that is based on such a direct oxidation reaction at the gas/solid interface represents a promising approach for SO2 capture. PMID:27123922

  2. Physiological activities of hydroxyl fatty acids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In the search of value-added products from surplus soybean oil, we produced many new hydroxy fatty acids through microbial bioconversion. Hydroxy fatty acids are used in a wide range of industrial products, such as resins, waxes, nylons plastics, lubricants, cosmetics, and additives in coatings and...

  3. Moringa oleifera Lam. seed extract prevents fat diet induced oxidative stress in mice and protects liver cell-nuclei from hydroxyl radical mediated damage.

    PubMed

    Das, Nilanjan; Ganguli, Debdutta; Dey, Sanjit

    2015-12-01

    High fat diet (HFD) prompts metabolic pattern inducing reactive oxygen species (ROS) production in mitochondria thereby triggering multitude of chronic disorders in human. Antioxidants from plant sources may be an imperative remedy against this disorder. However, it requires scientific validation. In this study, we explored if (i) Moringa oleifera seed extract (MoSE) can neutralize ROS generated in HFD fed mice; (ii) protect cell-nuclei damage developed by Fenton reaction in vitro. Swiss mice were fed with HFD to develop oxidative stress model (HFD group). Other groups were control, seed extract alone treated, and MoSE simultaneously (HS) treated. Treatment period was of 15 days. Antioxidant enzymes with tissue nitrite content (TNC) and lipid peroxidation (LPO) were estimated from liver homogenate. HS group showed significantly higher (P < 0.05) superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), reduced glutathione (GSH) activity, and ferric reducing antioxidant power (FRAP) compared to only HFD fed group. Further, TNC and LPO decreased significantly (P < 0.05) in HS group compared to HFD fed group. MoSE also protected hepatocytes nuclei from the hydroxyl radicals generated by Fenton reaction. MoSE was found to be polyphenol rich with potent reducing power, free radicals and hydroxyl radicals scavenging activity. Thus, MoSE exhibited robust antioxidant prospective to neutralize ROS developed in HFD fed mice and also protected the nuclei damage from hydroxyl radicals. Hence, it can be used as herbal medication against HFD induced ROS mediated disorders.

  4. Moringa oleifera Lam. seed extract prevents fat diet induced oxidative stress in mice and protects liver cell-nuclei from hydroxyl radical mediated damage.

    PubMed

    Das, Nilanjan; Ganguli, Debdutta; Dey, Sanjit

    2015-12-01

    High fat diet (HFD) prompts metabolic pattern inducing reactive oxygen species (ROS) production in mitochondria thereby triggering multitude of chronic disorders in human. Antioxidants from plant sources may be an imperative remedy against this disorder. However, it requires scientific validation. In this study, we explored if (i) Moringa oleifera seed extract (MoSE) can neutralize ROS generated in HFD fed mice; (ii) protect cell-nuclei damage developed by Fenton reaction in vitro. Swiss mice were fed with HFD to develop oxidative stress model (HFD group). Other groups were control, seed extract alone treated, and MoSE simultaneously (HS) treated. Treatment period was of 15 days. Antioxidant enzymes with tissue nitrite content (TNC) and lipid peroxidation (LPO) were estimated from liver homogenate. HS group showed significantly higher (P < 0.05) superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), reduced glutathione (GSH) activity, and ferric reducing antioxidant power (FRAP) compared to only HFD fed group. Further, TNC and LPO decreased significantly (P < 0.05) in HS group compared to HFD fed group. MoSE also protected hepatocytes nuclei from the hydroxyl radicals generated by Fenton reaction. MoSE was found to be polyphenol rich with potent reducing power, free radicals and hydroxyl radicals scavenging activity. Thus, MoSE exhibited robust antioxidant prospective to neutralize ROS developed in HFD fed mice and also protected the nuclei damage from hydroxyl radicals. Hence, it can be used as herbal medication against HFD induced ROS mediated disorders. PMID:26742324

  5. Skills for Living: Group Counseling Activities for Elementary Students.

    ERIC Educational Resources Information Center

    Morganett, Rosemarie Smead

    This book can help counselors in the school or mental health setting create meaningful group experiences for children who, for whatever reason, are behind in social and life skill development. The group agendas have been developed with children from grades 2-5 in mind. Although each topic stands alone, children can benefit from more than one…

  6. The Fantastic Facilitator: Engaging Activities for Leading Groups.

    ERIC Educational Resources Information Center

    Duttweiler, Patricia Cloud

    This document is designed to help facilitators with the formation and development of effective teams of people who have no previous history as a team and no training in group processes. Part 1 provides a narrative explanation of the stages of group development (investing in membership, forming attachments to subgroups, confronting/debating issues,…

  7. A characterization study of a hydroxylated polycrystalline tin oxide surface

    NASA Technical Reports Server (NTRS)

    Hoflund, Gar B.; Grogan, Austin L., Jr.; Asbury, Douglas A.; Schryer, David R.

    1989-01-01

    In this study Auger electron spectroscopy, electron spectroscopy for chemical analysis (ESCA) and electron-stimulated desorption (ESD) have been used to examine a polycrystalline tin oxide surface before and after annealing in vacuum at 500 C. Features due to surface hydroxyl groups are present in both the ESCA and ESD spectra, and ESD shows that several chemical states of hydrogen are present. Annealing at 500 C causes a large reduction in the surface hydrogen concentration but not complete removal.

  8. Surface studies of hydroxylated multi-wall carbon nanotubes

    SciTech Connect

    Bradley, Robert; Cassity, Kelby; Andrews, Rodney; Meier, Mark; Osbeck, Susan; Andreu, Aurik; Johnston, Colin; Crossley, Alison

    2012-01-01

    CVD grown MWCNTs, of typical diameter 5 to 50 nm and with approximately 15-20 concentric graphene layers in the multi-walls, have been surface functionalised using the Fenton hydroxylation reaction. HRTEM reveals little physical difference between the treated and untreated materials; images from both exhibit similar multi-wall structure and contain evidence for some low-level disruption of the very outermost layers. Raman spectra from the two types of nanotubes are almost identical displaying the disorder (D) peaks at approximately 1350 cm{sup -1} and graphite (G) peaks at approximately 1580 cm{sup -1}, characteristic of graphene-based carbon materials, in approximately equal intensity ratios. Equilibrium adsorption data for nitrogen at 77 K leads to BET surface areas of 60.4 m{sup 2} g{sup -1} for the untreated and 71.8 m{sup 2} g{sup -1} for the hydroxylated samples; the increase in area being due to separation of the tube-bundles during functionalization. This is accompanied by a decrease in measured porosity, mostly at high relative pressures of nitrogen, i.e. where larger (meso 2-5 nm and macro >5 nm) pores are being filled, which is consistent with an attendant loss of inter-tube capillarity. X-ray photoelectron spectroscopy (XPS) shows that hydroxylation increases the nanotube surface oxygen level from 4.3 at.% to 22.3 at.%; chemical shift data indicate that approximately 75% of that oxygen is present as hydroxyl (-OH) groups. Water vapour adsorption by the hydroxylated surfaces leads to Type II isotherms which are characteristic of relatively high numbers of hydrogen bonding interactions compared to the untreated materials which exhibit Type III curves. This difference in polar surface energy is confirmed by calorimetric enthalpies of immersion in water which are -54 mJ m{sup -2} for the untreated and -192 mJ m{sup -2} for the hydroxylated materials. The treated materials therefore have significantly increased water wettability/dispersivity and a greater

  9. An Activity Group Experience for Disengaged Elderly Persons.

    ERIC Educational Resources Information Center

    Harris, John Ewing; Bodden, Jack L.

    1978-01-01

    Tested the activity theory (which proposes that elderly persons remain in active contact with their environment) and disengagement theory (which suggests adjustment comes through reduction of activity and social contact). Disengaged elderly were identified. Subjects demonstrated significant improvement over the untreated control subjects. Results…

  10. Group Problem Solving as a Zone of Proximal Development activity

    NASA Astrophysics Data System (ADS)

    Brewe, Eric

    2006-12-01

    Vygotsky described learning as a process, intertwined with development, which is strongly influenced by social interactions with others that are at differing developmental stages.i These interactions create a Zone of Proximal Development for each member of the interaction. Vygotsky’s notion of social constructivism is not only a theory of learning, but also of development. While teaching introductory physics in an interactive format, I have found manifestations of Vygotsky’s theory in my classroom. The source of evidence is a paired problem solution. A standard mechanics problem was solved by students in two classes as a homework assignment. Students handed in the homework and then solved the same problem in small groups. The solutions to both the group and individual problem were assessed by multiple reviewers. In many cases the group score was the same as the highest individual score in the group, but in some cases, the group score was higher than any individual score. For this poster, I will analyze the individual and group scores and focus on three groups solutions and video that provide evidence of learning through membership in a Zone of Proximal Development. Endnotes i L. Vygotsky -Mind and society: The development of higher mental processes. Cambridge, MA: Harvard University Press. (1978).

  11. Differential Effects of Collagen Prolyl 3-Hydroxylation on Skeletal Tissues

    PubMed Central

    Homan, Erica P.; Lietman, Caressa; Grafe, Ingo; Lennington, Jennifer; Morello, Roy; Napierala, Dobrawa; Jiang, Ming-Ming; Munivez, Elda M.; Dawson, Brian; Bertin, Terry K.; Chen, Yuqing; Lua, Rhonald; Lichtarge, Olivier; Hicks, John; Weis, Mary Ann; Eyre, David; Lee, Brendan H. L.

    2014-01-01

    Mutations in the genes encoding cartilage associated protein (CRTAP) and prolyl 3-hydroxylase 1 (P3H1 encoded by LEPRE1) were the first identified causes of recessive Osteogenesis Imperfecta (OI). These proteins, together with cyclophilin B (encoded by PPIB), form a complex that 3-hydroxylates a single proline residue on the α1(I) chain (Pro986) and has cis/trans isomerase (PPIase) activity essential for proper collagen folding. Recent data suggest that prolyl 3-hydroxylation of Pro986 is not required for the structural stability of collagen; however, the absence of this post-translational modification may disrupt protein-protein interactions integral for proper collagen folding and lead to collagen over-modification. P3H1 and CRTAP stabilize each other and absence of one results in degradation of the other. Hence, hypomorphic or loss of function mutations of either gene cause loss of the whole complex and its associated functions. The relative contribution of losing this complex's 3-hydroxylation versus PPIase and collagen chaperone activities to the phenotype of recessive OI is unknown. To distinguish between these functions, we generated knock-in mice carrying a single amino acid substitution in the catalytic site of P3h1 (Lepre1H662A). This substitution abolished P3h1 activity but retained ability to form a complex with Crtap and thus the collagen chaperone function. Knock-in mice showed absence of prolyl 3-hydroxylation at Pro986 of the α1(I) and α1(II) collagen chains but no significant over-modification at other collagen residues. They were normal in appearance, had no growth defects and normal cartilage growth plate histology but showed decreased trabecular bone mass. This new mouse model recapitulates elements of the bone phenotype of OI but not the cartilage and growth phenotypes caused by loss of the prolyl 3-hydroxylation complex. Our observations suggest differential tissue consequences due to selective inactivation of P3H1 hydroxylase activity

  12. Tyrosine Hydroxylation in Betalain Pigment Biosynthesis Is Performed by Cytochrome P450 Enzymes in Beets (Beta vulgaris).

    PubMed

    Sunnadeniya, Rasika; Bean, Alexander; Brown, Matthew; Akhavan, Neda; Hatlestad, Gregory; Gonzalez, Antonio; Symonds, V Vaughan; Lloyd, Alan

    2016-01-01

    Yellow and red-violet betalain plant pigments are restricted to several families in the order Caryophyllales, where betacyanins play analogous biological roles to anthocyanins. The initial step in betalain biosynthesis is the hydroxylation of tyrosine to form L-DOPA. Using gene expression experiments in beets, yeast, and Arabidopsis, along with HPLC/MS analysis, the present study shows that two novel cytochrome P450 (CYP450) enzymes, CYP76AD6 and CYP76AD5, and the previously described CYP76AD1 can perform this initial step. Co-expressing these CYP450s with DOPA 4,5-dioxygenase in yeast, and overexpression of these CYP450s in yellow beets show that CYP76AD1 efficiently uses L-DOPA leading to red betacyanins while CYP76AD6 and CYP76AD5 lack this activity. Furthermore, CYP76AD1 can complement yellow beetroots to red while CYP76AD6 and CYP76AD5 cannot. Therefore CYP76AD1 uniquely performs the beet R locus function and beets appear to be genetically redundant for tyrosine hydroxylation. These new functional data and ancestral character state reconstructions indicate that tyrosine hydroxylation alone was the most likely ancestral function of the CYP76AD alpha and beta groups and the ability to convert L-DOPA to cyclo-DOPA evolved later in the alpha group.

  13. Tyrosine Hydroxylation in Betalain Pigment Biosynthesis Is Performed by Cytochrome P450 Enzymes in Beets (Beta vulgaris).

    PubMed

    Sunnadeniya, Rasika; Bean, Alexander; Brown, Matthew; Akhavan, Neda; Hatlestad, Gregory; Gonzalez, Antonio; Symonds, V Vaughan; Lloyd, Alan

    2016-01-01

    Yellow and red-violet betalain plant pigments are restricted to several families in the order Caryophyllales, where betacyanins play analogous biological roles to anthocyanins. The initial step in betalain biosynthesis is the hydroxylation of tyrosine to form L-DOPA. Using gene expression experiments in beets, yeast, and Arabidopsis, along with HPLC/MS analysis, the present study shows that two novel cytochrome P450 (CYP450) enzymes, CYP76AD6 and CYP76AD5, and the previously described CYP76AD1 can perform this initial step. Co-expressing these CYP450s with DOPA 4,5-dioxygenase in yeast, and overexpression of these CYP450s in yellow beets show that CYP76AD1 efficiently uses L-DOPA leading to red betacyanins while CYP76AD6 and CYP76AD5 lack this activity. Furthermore, CYP76AD1 can complement yellow beetroots to red while CYP76AD6 and CYP76AD5 cannot. Therefore CYP76AD1 uniquely performs the beet R locus function and beets appear to be genetically redundant for tyrosine hydroxylation. These new functional data and ancestral character state reconstructions indicate that tyrosine hydroxylation alone was the most likely ancestral function of the CYP76AD alpha and beta groups and the ability to convert L-DOPA to cyclo-DOPA evolved later in the alpha group. PMID:26890886

  14. Tyrosine Hydroxylation in Betalain Pigment Biosynthesis Is Performed by Cytochrome P450 Enzymes in Beets (Beta vulgaris)

    PubMed Central

    Sunnadeniya, Rasika; Bean, Alexander; Brown, Matthew; Akhavan, Neda; Hatlestad, Gregory; Gonzalez, Antonio; Symonds, V. Vaughan; Lloyd, Alan

    2016-01-01

    Yellow and red-violet betalain plant pigments are restricted to several families in the order Caryophyllales, where betacyanins play analogous biological roles to anthocyanins. The initial step in betalain biosynthesis is the hydroxylation of tyrosine to form L-DOPA. Using gene expression experiments in beets, yeast, and Arabidopsis, along with HPLC/MS analysis, the present study shows that two novel cytochrome P450 (CYP450) enzymes, CYP76AD6 and CYP76AD5, and the previously described CYP76AD1 can perform this initial step. Co-expressing these CYP450s with DOPA 4,5-dioxygenase in yeast, and overexpression of these CYP450s in yellow beets show that CYP76AD1 efficiently uses L-DOPA leading to red betacyanins while CYP76AD6 and CYP76AD5 lack this activity. Furthermore, CYP76AD1 can complement yellow beetroots to red while CYP76AD6 and CYP76AD5 cannot. Therefore CYP76AD1 uniquely performs the beet R locus function and beets appear to be genetically redundant for tyrosine hydroxylation. These new functional data and ancestral character state reconstructions indicate that tyrosine hydroxylation alone was the most likely ancestral function of the CYP76AD alpha and beta groups and the ability to convert L-DOPA to cyclo-DOPA evolved later in the alpha group. PMID:26890886

  15. New strategies for exploring RNA's 2'-OH expose the importance of solvent during group II intron catalysis.

    PubMed

    Gordon, Peter M; Fong, Robert; Deb, Shirshendu K; Li, Nan-Sheng; Schwans, Jason P; Ye, Jing-Dong; Piccirilli, Joseph A

    2004-02-01

    The 2'-hydroxyl group contributes inextricably to the functional behavior of many RNA molecules, fulfilling numerous essential chemical roles. To assess how hydroxyl groups impart functional behavior to RNA, we developed a series of experimental strategies using an array of nucleoside analogs. These strategies provide the means to investigate whether a hydroxyl group influences function directly (via hydrogen bonding or metal ion coordination), indirectly (via space-filling capacity, inductive effects, and sugar conformation), or through interactions with solvent. The nucleoside analogs span a broad range of chemical diversity, such that quantitative structure activity relationships (QSAR) now become possible in the exploration of RNA biology. We employed these strategies to investigate the spliced exons reopening (SER) reaction of the group II intron. Our results suggest that the cleavage site 2'-hydroxyl may mediate an interaction with a water molecule.

  16. Parents' Networking Strategies: Participation of Formal and Informal Parent Groups in School Activities and Decisions

    ERIC Educational Resources Information Center

    Wanat, Carolyn L.

    2010-01-01

    This case study examined parent groups' involvement in school activities and their participation in decision making. Research questions included the following: (1) What is the nature of parent groups in schools? (2) What activities and issues gain parent groups' attention and participation? (3) How do parent groups communicate concerns about…

  17. Scaffolding of Small Groups' Metacognitive Activities with an Avatar

    ERIC Educational Resources Information Center

    Molenaar, Inge; Chiu, Ming Ming; Sleegers, Peter; van Boxtel, Carla

    2011-01-01

    Metacognitive scaffolding in a computer-supported learning environment can influence students' metacognitive activities, metacognitive knowledge and domain knowledge. In this study we analyze how metacognitive activities mediate the relationships between different avatar scaffolds on students' learning. Multivariate, multilevel analysis of the…

  18. Supporting Mobile Collaborative Activities through Scaffolded Flexible Grouping

    ERIC Educational Resources Information Center

    Boticki, Ivica; Looi, Chee-Kit; Wong, Lung-Hsiang

    2011-01-01

    Within the field of Mobile Computer-Supported Collaborative Learning (mCSCL), we are interested in exploring the space of collaborative activities that enable students to practice communication, negotiation and decision-making skills. Collaboration is via learning activities that circumvent the constraints of fixed seating or locations of…

  19. Selective Aromatic C–H Hydroxylation Enabled by η6-Coordination to Iridium(III)

    PubMed Central

    D'Amato, Erica M.; Neumann, Constanze N.; Ritter, Tobias

    2016-01-01

    We report an aromatic C–H hydroxylation protocol in which the arene is activated through η6-coordination to an iridium(III) complex. η6-Coordination of the arene increases its electrophilicity and allows for high positional selectivity of hydroxylation at the site of least electron density. Through investigation of intermediate η5-cyclohexadienyl adducts and arene exchange reactions, we evaluate incorporation of arene π-activation into a catalytic cycle for C–H functionalization. PMID:26877574

  20. Presence of Hydrogen Peroxide, a Source of Hydroxyl Radicals, in Acid Electrolyzed Water

    PubMed Central

    Mokudai, Takayuki; Nakamura, Keisuke; Kanno, Taro; Niwano, Yoshimi

    2012-01-01

    Background Acid electrolyzed water (AEW), which is produced through the electrolysis of dilute sodium chloride (NaCl) or potassium chloride solution, is used as a disinfectant in various fields because of its potent antimicrobial activity. The hydroxyl radical, an oxygen radical species, is often suggested as a putative active ingredient for AEW antimicrobial activity. Methodology/Principal Findings The aim of the present study is to detect hydroxyl radicals in AEW. The hydroxyl radicals in AEW prepared under different conditions were determined using an electron spin resonance (ESR) technique. A signal from 5,5-dimethyl-1-pyrroline N-oxide (DMPO)-OH, an adduct of DMPO and the hydroxyl radical, was detected in AEW prepared by double or triple electrolyses of 1% NaCl but not of 0.1% NaCl solution. Then the presence of hydrogen peroxide as a proposed source of hydroxyl radicals was examined using a combination of ESR and a Fenton reaction. The DMPO-OH signal was clearly detected, even in AEW prepared by single electrolysis of 0.1% NaCl solution, when ferrous sulfate was added to induce a Fenton reaction, indicating the presence of hydrogen peroxide in the AEW. Since sodium formate, a hydroxyl radical scavenger, did not affect the bactericidal activity of AEW, it is concluded that the radical is unlikely to contribute to the antimicrobial activity of AEW, although a small amount of the radical is produced from hydrogen peroxide. Dimethyl sulfoxide, the other hydroxyl radical scavenger used in the present study, canceled the bactericidal activity of AEW, accompanied by complete depletion of free available chlorine, suggesting that hypochlorous acid is probably a major contributor to the antimicrobial activity. Conclusions It is strongly suggested that although hydrogen peroxide is present in AEW as a source of hydroxyl radicals, the antimicrobial activity of AEW does not depend on these radicals. PMID:23029505

  1. Continuous Flow Reactor for Hydroxylation of Benzene to Phenol by Hydrogen Peroxide

    NASA Astrophysics Data System (ADS)

    Zhang, Li; Liu, Hui-hui; Li, Gui-ying; Hu, Chang-wei

    2012-10-01

    The direct hydroxylation of benzene to phenol catalyzed by activated carbon-supported Fe (Fe/AC) in acetonitrile using H2O2 as the oxidant was studied in a continuous flow reactor. Results showed that the continuous operation could obtain high phenol yield of 28.1%, coupled with the turnover frequency of 3 h-1, and high selectivity of 98% under mild condition. The catalyst was characterized by N2 adsorption/desorption, Boehm titration, X-ray photoelectron spectra, and Fourier transform infrared spectroscopy. It was observed that iron may interact with the carboxyl group forming iron-carboxylate like species, which act as the active phase. The apparent activation energy obtained by fitting an Arrhenius model to the experimental data was 13.4 kJ/mol. The reaction order was calculated to be about 1, 0.2 for benzene and 0.7 for H2O2.

  2. Classroom-Based Interdependent Group Contingencies Increase Children's Physical Activity

    ERIC Educational Resources Information Center

    Kuhl, Sarah; Rudrud, Eric H.; Witts, Benjamin N.; Schulze, Kimberly A.

    2015-01-01

    This study investigated the effects of 2 interdependent group contingencies (individual vs. cumulative classroom goal setting) on the number of pedometer-recorded steps taken per day. Thirty third-grade students in 2 classrooms participated. An ABACX design was conducted in which the X phase referred to a replication of the most successful phase…

  3. 4'-hydroxylation of flurbiprofen by rat liver microsomes in fasting and feeding conditions.

    PubMed

    Shimizu, Makiko; Matsushita, Reiko; Matsumoto, Yoshiaki; Fukuoka, Masamichi

    2003-10-01

    We examined the 4'-hydroxylation of flurbiprofen in rat hepatocytes and liver microsomes in order to know whether the metabolism of flurbiprofen is changed on its administration to experimental animals after overnight fasting, because starvation and fasting change both the composition of cytochrome P450s (CYPs) and metabolic activity. CYPs involved in the hydroxylation were determined by various CYP inhibitors and inhibitory antibodies against rat CYP2C11 and CYP2E1 using the microsomes in fasting and feeding. The results provided a possibiliy that the 4'-hydroxylation might be regulated by CYP2C11, but not by CYP2E1, at fasting rather than feeding.

  4. Conversation Strategies: Pair and Group Activities for Developing Communicative Competence.

    ERIC Educational Resources Information Center

    Kehe, David; Kehe, Peggy Dustin

    The guide is designed for use in English-as-a-Second-Language instruction at the intermediate level. The activities are designed to be enjoyable and encourage students to interact, but also to be non-threatening to even the most reserved students. The exercises develop strategic conversation skills. Each has three parts: a teacher's introduction;…

  5. Novel, high-activity hydroprocessing catalysts: Iron group phosphides

    NASA Astrophysics Data System (ADS)

    Wang, Xianqin

    A series of iron, cobalt and nickel transition metal phosphides was synthesized by means of temperature-programmed reduction (TPR) of the corresponding phosphates. The same materials, Fe2P, CoP and NO, were also prepared on a silica (SiO2) support. The phase purity of these catalysts was established by x-ray diffraction (XRD), and the surface properties were determined by N2 BET specific surface area (Sg) measurements and CO chemisorption. The activities of the silica-supported catalysts were tested in a three-phase trickle bed reactor for the simultaneous hydrodenitrogenation (HDN) of quinoline and hydrodesulfurization (HDS) of dibenzothiophene using a model liquid feed at realistic conditions (30 atm, 370°C). The reactivity studies showed that the nickel phosphide (Ni2P/SiO2) was the most active of the catalysts. Compared with a commercial Ni-Mo-S/gamma-Al 2O3 catalyst at the same conditions, Ni2P/silica had a substantially higher HDS activity (100% vs. 76%) and HDN activity (82% vs. 38%). Because of their good hydrotreating activity, an extensive study of the preparation of silica supported nickel phosphides, Ni2P/SiO 2, was carried out. The parameters investigated were the phosphorus content and the weight loading of the active phase. The most active composition was found to have a starting synthesis Ni/P ratio close to 1/2, and the best loading of this sample on silica was observed to be 18 wt.%. Extended x-ray absorption fine structure (EXAFS) and x-ray absorption near edge spectroscopy (XANES) measurements were employed to determine the structures of the supported samples. The main phase before and after reaction was found to be Ni2P, but some sulfur was found to be retained after reaction. A comprehensive scrutiny of the HDN reaction mechanism was also made over the Ni2P/SiO2 sample (Ni/P = 1/2) by comparing the HDN activity of a series of piperidine derivatives of different structure. It was found that piperidine adsorption involved an alpha-H activation

  6. Working Group 5: Measurements technology and active experiments

    NASA Technical Reports Server (NTRS)

    Whipple, E.; Barfield, J. N.; Faelthammar, C.-G.; Feynman, J.; Quinn, J. N.; Roberts, W.; Stone, N.; Taylor, W. L.

    1986-01-01

    Technology issues identified by working groups 5 are listed. (1) New instruments are needed to upgrade the ability to measure plasma properties in space. (2) Facilities should be developed for conducting a broad range of plasma experiments in space. (3) The ability to predict plasma weather within magnetospheres should be improved and a capability to modify plasma weather developed. (4) Methods of control of plasma spacecraft and spacecraft plasma interference should be upgraded. (5) The space station laboratory facilities should be designed with attention to problems of flexibility to allow for future growth. These issues are discussed.

  7. Two Structures of an N-Hydroxylating Flavoprotein Monooxygenase

    PubMed Central

    Olucha, Jose; Meneely, Kathleen M.; Chilton, Annemarie S.; Lamb, Audrey L.

    2011-01-01

    The ornithine hydroxylase from Pseudomonas aeruginosa (PvdA) catalyzes the FAD-dependent hydroxylation of the side chain amine of ornithine, which is subsequently formylated to generate the iron-chelating hydroxamates of the siderophore pyoverdin. PvdA belongs to the class B flavoprotein monooxygenases, which catalyze the oxidation of substrates using NADPH as the electron donor and molecular oxygen. Class B enzymes include the well studied flavin-containing monooxygenases and Baeyer-Villiger monooxygenases. The first two structures of a class B N-hydroxylating monooxygenase were determined with FAD in oxidized (1.9 Å resolution) and reduced (3.03 Å resolution) states. PvdA has the two expected Rossmann-like dinucleotide-binding domains for FAD and NADPH and also a substrate-binding domain, with the active site at the interface between the three domains. The structures have NADP(H) and (hydroxy)ornithine bound in a solvent-exposed active site, providing structural evidence for substrate and co-substrate specificity and the inability of PvdA to bind FAD tightly. Structural and biochemical evidence indicates that NADP+ remains bound throughout the oxidative half-reaction, which is proposed to shelter the flavin intermediates from solvent and thereby prevent uncoupling of NADPH oxidation from hydroxylated product formation. PMID:21757711

  8. Characterization of inhibitory mechanism and antifungal activity between group-1 and group-2 phytocystatins from taro (Colocasia esculenta).

    PubMed

    Wang, Ke-Ming; Kumar, Senthil; Cheng, Yi-Sheng; Venkatagiri, Shripathi; Yang, Ai-Hwa; Yeh, Kai-Wun

    2008-10-01

    Tarocystatin from Colocasia esculenta, a group-2 phytocystatin, is a defense protein against phytopathogenic nematodes and fungi. It is composed of a highly conserved N-terminal region, which is homological to group-1 cystatin, and a repetitive peptide at the C-terminus. The purified recombinant proteins of tarocystatin, such as full-length (FL), N-terminus (Nt) and C-terminus (Ct) peptides, were produced and their inhibitory activities against papain as well as their antifungal effects were investigated. Kinetic analysis revealed that FL peptide exhibited mixed type inhibition (K(ia) = 0.098 microM and K(ib) = 0.252 microM) and Nt peptide showed competitive inhibition (K(i) = 0.057 microM), whereas Ct peptide possessed weak papain activation properties. A shift in the inhibitory pattern from competitive inhibition of Nt peptide alone to mixed type inhibition of FL peptide implied that the Ct peptide has an regulatory effect on the function of FL peptide. Based on the inhibitory kinetics of FL (group-2) and Nt (group-1) peptides on papain activity, an inhibitory mechanism of group-2 phytocystatins and a regulatory mechanism of extended Ct peptide have each been proposed. By contrast, the antifungal activity of Nt peptide appeared to be greater than that of FL peptide, and the Ct peptide showed no effect on antifungal activity, indicating that the antifungal effect is not related to proteinase inhibitory activity. The results are valid for most phytocystatins with respect to the inhibitory mechanism against cysteine proteinase.

  9. Characterization of inhibitory mechanism and antifungal activity between group-1 and group-2 phytocystatins from taro (Colocasia esculenta).

    PubMed

    Wang, Ke-Ming; Kumar, Senthil; Cheng, Yi-Sheng; Venkatagiri, Shripathi; Yang, Ai-Hwa; Yeh, Kai-Wun

    2008-10-01

    Tarocystatin from Colocasia esculenta, a group-2 phytocystatin, is a defense protein against phytopathogenic nematodes and fungi. It is composed of a highly conserved N-terminal region, which is homological to group-1 cystatin, and a repetitive peptide at the C-terminus. The purified recombinant proteins of tarocystatin, such as full-length (FL), N-terminus (Nt) and C-terminus (Ct) peptides, were produced and their inhibitory activities against papain as well as their antifungal effects were investigated. Kinetic analysis revealed that FL peptide exhibited mixed type inhibition (K(ia) = 0.098 microM and K(ib) = 0.252 microM) and Nt peptide showed competitive inhibition (K(i) = 0.057 microM), whereas Ct peptide possessed weak papain activation properties. A shift in the inhibitory pattern from competitive inhibition of Nt peptide alone to mixed type inhibition of FL peptide implied that the Ct peptide has an regulatory effect on the function of FL peptide. Based on the inhibitory kinetics of FL (group-2) and Nt (group-1) peptides on papain activity, an inhibitory mechanism of group-2 phytocystatins and a regulatory mechanism of extended Ct peptide have each been proposed. By contrast, the antifungal activity of Nt peptide appeared to be greater than that of FL peptide, and the Ct peptide showed no effect on antifungal activity, indicating that the antifungal effect is not related to proteinase inhibitory activity. The results are valid for most phytocystatins with respect to the inhibitory mechanism against cysteine proteinase. PMID:18785929

  10. Contralateral delay activity tracks the influence of Gestalt grouping principles on active visual working memory representations.

    PubMed

    Peterson, Dwight J; Gözenman, Filiz; Arciniega, Hector; Berryhill, Marian E

    2015-10-01

    Recent studies have demonstrated that factors influencing perception, such as Gestalt grouping cues, can influence the storage of information in visual working memory (VWM). In some cases, stationary cues, such as stimulus similarity, lead to superior VWM performance. However, the neural correlates underlying these benefits to VWM performance remain unclear. One neural index, the contralateral delay activity (CDA), is an event-related potential that shows increased amplitude according to the number of items held in VWM and asymptotes at an individual's VWM capacity limit. Here, we applied the CDA to determine whether previously reported behavioral benefits supplied by similarity, proximity, and uniform connectedness were reflected as a neural savings such that the CDA amplitude was reduced when these cues were present. We implemented VWM change-detection tasks with arrays including similarity and proximity (Experiment 1); uniform connectedness (Experiments 2a and 2b); and similarity/proximity and uniform connectedness (Experiment 3). The results indicated that when there was a behavioral benefit to VWM, this was echoed by a reduction in CDA amplitude, which suggests more efficient processing. However, not all perceptual grouping cues provided a VWM benefit in the same measure (e.g., accuracy) or of the same magnitude. We also found unexpected interactions between cues. We observed a mixed bag of effects, suggesting that these powerful perceptual grouping benefits are not as predictable in VWM. The current findings indicate that when grouping cues produce behavioral benefits, there is a parallel reduction in the neural resources required to maintain grouped items within VWM.

  11. Contralateral delay activity tracks the influence of Gestalt grouping principles on active visual working memory representations.

    PubMed

    Peterson, Dwight J; Gözenman, Filiz; Arciniega, Hector; Berryhill, Marian E

    2015-10-01

    Recent studies have demonstrated that factors influencing perception, such as Gestalt grouping cues, can influence the storage of information in visual working memory (VWM). In some cases, stationary cues, such as stimulus similarity, lead to superior VWM performance. However, the neural correlates underlying these benefits to VWM performance remain unclear. One neural index, the contralateral delay activity (CDA), is an event-related potential that shows increased amplitude according to the number of items held in VWM and asymptotes at an individual's VWM capacity limit. Here, we applied the CDA to determine whether previously reported behavioral benefits supplied by similarity, proximity, and uniform connectedness were reflected as a neural savings such that the CDA amplitude was reduced when these cues were present. We implemented VWM change-detection tasks with arrays including similarity and proximity (Experiment 1); uniform connectedness (Experiments 2a and 2b); and similarity/proximity and uniform connectedness (Experiment 3). The results indicated that when there was a behavioral benefit to VWM, this was echoed by a reduction in CDA amplitude, which suggests more efficient processing. However, not all perceptual grouping cues provided a VWM benefit in the same measure (e.g., accuracy) or of the same magnitude. We also found unexpected interactions between cues. We observed a mixed bag of effects, suggesting that these powerful perceptual grouping benefits are not as predictable in VWM. The current findings indicate that when grouping cues produce behavioral benefits, there is a parallel reduction in the neural resources required to maintain grouped items within VWM. PMID:26018644

  12. Meta-Analysis of Group Learning Activities: Empirically Based Teaching Recommendations

    ERIC Educational Resources Information Center

    Tomcho, Thomas J.; Foels, Rob

    2012-01-01

    Teaching researchers commonly employ group-based collaborative learning approaches in Teaching of Psychology teaching activities. However, the authors know relatively little about the effectiveness of group-based activities in relation to known psychological processes associated with group dynamics. Therefore, the authors conducted a meta-analytic…

  13. Engager and Avoider Behaviour in Types of Activities Performed by Out-of-Class Learning Groups

    ERIC Educational Resources Information Center

    Yan, Louisa; Kember, David

    2004-01-01

    This study examines the out-of-class learning activities undertaken, at the students' volition, by groups of students. Data were gathered through 57 individual and 15 focus group interviews with university students in Hong Kong. Group activities reported included: copying, sharing material, consulting peers, consulting teachers, studying and…

  14. Current activities of the Atmospheric Composition Sub-Group of the CEOS Working Group on Calibration and Validation

    NASA Astrophysics Data System (ADS)

    Bojkov, Bojan

    The Atmospheric Sub-Group of the CEOS Calibration and Validation Working Group (CEOS WGCV/ASCG) was established in November 2001 with mission to ensure accurate and traceable calibration of remotely-sensed atmospheric chemistry radiance data and validation of higher level products, for application to atmospheric chemistry and climate research. This working-group, consisting of 15 members from space agencies and other relevant agencies and organizations with broad experience in calibration, modeling, algorithm development and validation, meet on an annual basis to promote international collaboration and technical exchanges, encourage interactions between mission scientists and data users, recommend network validation sites, develop comprehensive validation methodologies involving ground-based and space-borne assets, and specify comprehensive and consistent multi-mission validation datasets. Recent activities of the ACSG, including the recent ground-based intercomparisons, the ongoing NASA-ESA-NDACC validation data sharing activities, and the planned multi-agency CO2 validation efforts, will be presented.

  15. Electron stimulated hydroxylation of a metal supported silicate film.

    PubMed

    Yu, Xin; Emmez, Emre; Pan, Qiushi; Yang, Bing; Pomp, Sascha; Kaden, William E; Sterrer, Martin; Shaikhutdinov, Shamil; Freund, Hans-Joachim; Goikoetxea, Itziar; Wlodarczyk, Radoslaw; Sauer, Joachim

    2016-02-01

    Water adsorption on a double-layer silicate film was studied by using infrared reflection-absorption spectroscopy, thermal desorption spectroscopy and scanning tunneling microscopy. Under vacuum conditions, small amounts of silanols (Si-OH) could only be formed upon deposition of an ice-like (amorphous solid water, ASW) film and subsequent heating to room temperature. Silanol coverage is considerably enhanced by low-energy electron irradiation of an ASW pre-covered silicate film. The degree of hydroxylation can be tuned by the irradiation parameters (beam energy, exposure) and the ASW film thickness. The results are consistent with a generally accepted picture that hydroxylation occurs through hydrolysis of siloxane (Si-O-Si) bonds in the silica network. Calculations using density functional theory show that this may happen on Si-O-Si bonds, which are either parallel (i.e., in the topmost silicate layer) or vertical to the film surface (i.e., connecting two silicate layers). In the latter case, the mechanism may additionally involve the reaction with a metal support underneath. The observed vibrational spectra are dominated by terminal silanol groups (ν(OD) band at 2763 cm(-1)) formed by hydrolysis of vertical Si-O-Si linkages. Film dehydroxylation fully occurs only upon heating to very high temperatures (∼ 1200 K) and is accompanied by substantial film restructuring, and even film dewetting upon cycling hydroxylation/dehydroxylation treatment.

  16. Structure, electronic properties, and aggregation behavior of hydroxylated carbon nanotubes

    NASA Astrophysics Data System (ADS)

    López-Oyama, A. B.; Silva-Molina, R. A.; Ruíz-García, J.; Gámez-Corrales, R.; Guirado-López, R. A.

    2014-11-01

    We present a combined experimental and theoretical study to analyze the structure, electronic properties, and aggregation behavior of hydroxylated multiwalled carbon nanotubes (OH-MWCNT). Our MWCNTs have average diameters of ˜2 nm, lengths of approximately 100-300 nm, and a hydroxyl surface coverage θ˜0.1. When deposited on the air/water interface the OH-MWCNTs are partially soluble and the floating units interact and link with each other forming extended foam-like carbon networks. Surface pressure-area isotherms of the nanotube films are performed using the Langmuir balance method at different equilibration times. The films are transferred into a mica substrate and atomic force microscopy images show that the foam like structure is preserved and reveals fine details of their microstructure. Density functional theory calculations performed on model hydroxylated carbon nanotubes show that low energy atomic configurations are found when the OH groups form molecular islands on the nanotube's surface. This patchy behavior for the OH species is expected to produce nanotubes having reduced wettabilities, in line with experimental observations. OH doping yields nanotubes having small HOMO-LUMO energy gaps and generates a nanotube → OH direction for the charge transfer leading to the existence of more hole carriers in the structures. Our synthesized OH-MWCNTs might have promising applications.

  17. Structure, electronic properties, and aggregation behavior of hydroxylated carbon nanotubes

    SciTech Connect

    López-Oyama, A. B.; Silva-Molina, R. A.; Ruíz-García, J.; Guirado-López, R. A.; Gámez-Corrales, R.

    2014-11-07

    We present a combined experimental and theoretical study to analyze the structure, electronic properties, and aggregation behavior of hydroxylated multiwalled carbon nanotubes (OH–MWCNT). Our MWCNTs have average diameters of ∼2 nm, lengths of approximately 100–300 nm, and a hydroxyl surface coverage θ∼0.1. When deposited on the air/water interface the OH–MWCNTs are partially soluble and the floating units interact and link with each other forming extended foam-like carbon networks. Surface pressure-area isotherms of the nanotube films are performed using the Langmuir balance method at different equilibration times. The films are transferred into a mica substrate and atomic force microscopy images show that the foam like structure is preserved and reveals fine details of their microstructure. Density functional theory calculations performed on model hydroxylated carbon nanotubes show that low energy atomic configurations are found when the OH groups form molecular islands on the nanotube's surface. This patchy behavior for the OH species is expected to produce nanotubes having reduced wettabilities, in line with experimental observations. OH doping yields nanotubes having small HOMO–LUMO energy gaps and generates a nanotube → OH direction for the charge transfer leading to the existence of more hole carriers in the structures. Our synthesized OH–MWCNTs might have promising applications.

  18. Group average difference: a termination criterion for active contour.

    PubMed

    Chuah, Tong Kuan; Lim, Jun Hong; Poh, Chueh Loo

    2012-04-01

    This paper presents a termination criterion for active contour that does not involve alteration of the energy functional. The criterion is based on the area difference of the contour during evolution. In this criterion, the evolution of the contour terminates when the area difference fluctuates around a constant. The termination criterion is tested using parametric gradient vector flow active contour with contour resampling and normal force selection. The usefulness of the criterion is shown through its trend, speed, accuracy, shape insensitivity, and insensitivity to contour resampling. The metric used in the proposed criterion demonstrated a steadily decreasing trend. For automatic implementation in which different shapes need to be segmented, the proposed criterion demonstrated almost 50% and 60% total time reduction while achieving similar accuracy as compared with the pixel movement-based method in the segmentation of synthetic and real medical images, respectively. Our results also show that the proposed termination criterion is insensitive to shape variation and contour resampling. The criterion also possesses potential to be used for other kinds of snakes.

  19. Hydroxyl radical oxidation of feruloylated arabinoxylan.

    PubMed

    Bagdi, Attila; Tömösközi, Sándor; Nyström, Laura

    2016-11-01

    Feruloylated arabinoxylan (AX) has a unique capacity to form covalent gels in the presence of certain oxidizing agents. The present study demonstrates that hydroxyl radical oxidation does not provoke ferulic acid dimerization and thus oxidative gelation. We studied the hydroxyl radical mediated oxidation of an alkali-extracted AX preparation (purity: 92g/100g dry matter) that showed gel-forming capability upon peroxidase/hydrogen peroxide treatment. Hydroxyl radicals were produced with ascorbate-driven Fenton reaction and the radical formation was monitored with electron paramagnetic resonance, using a POBN/EtOH spin trapping system. Oxidation was carried out at different catalytic concentrations of iron (50 and 100μM) and at different temperatures (20°C, 50°C, and 80°C). It was demonstrated that hydroxyl radical oxidation does not provoke gel formation, but viscosity decrease in AX solution, which suggests polymer degradation. Furthermore, it was demonstrated that hydroxyl radical formation in AX solution can be initiated merely by increasing temperature. PMID:27516272

  20. Superfluid phase transition with activated velocity fluctuations: Renormalization group approach.

    PubMed

    Dančo, Michal; Hnatič, Michal; Komarova, Marina V; Lučivjanský, Tomáš; Nalimov, Mikhail Yu

    2016-01-01

    A quantum field model that incorporates Bose-condensed systems near their phase transition into a superfluid phase and velocity fluctuations is proposed. The stochastic Navier-Stokes equation is used for a generation of the velocity fluctuations. As such this model generalizes model F of critical dynamics. The field-theoretic action is derived using the Martin-Siggia-Rose formalism and path integral approach. The regime of equilibrium fluctuations is analyzed within the perturbative renormalization group method. The double (ε,δ)-expansion scheme is employed, where ε is a deviation from space dimension 4 and δ describes scaling of velocity fluctuations. The renormalization procedure is performed to the leading order. The main corollary gained from the analysis of the thermal equilibrium regime suggests that one-loop calculations of the presented models are not sufficient to make a definite conclusion about the stability of fixed points. We also show that critical exponents are drastically changed as a result of the turbulent background and critical fluctuations are in fact destroyed by the developed turbulence fluctuations. The scaling exponent of effective viscosity is calculated and agrees with expected value 4/3.

  1. Superfluid phase transition with activated velocity fluctuations: Renormalization group approach

    NASA Astrophysics Data System (ADS)

    Dančo, Michal; Hnatič, Michal; Komarova, Marina V.; Lučivjanský, Tomáš; Nalimov, Mikhail Yu.

    2016-01-01

    A quantum field model that incorporates Bose-condensed systems near their phase transition into a superfluid phase and velocity fluctuations is proposed. The stochastic Navier-Stokes equation is used for a generation of the velocity fluctuations. As such this model generalizes model F of critical dynamics. The field-theoretic action is derived using the Martin-Siggia-Rose formalism and path integral approach. The regime of equilibrium fluctuations is analyzed within the perturbative renormalization group method. The double (ɛ ,δ ) -expansion scheme is employed, where ɛ is a deviation from space dimension 4 and δ describes scaling of velocity fluctuations. The renormalization procedure is performed to the leading order. The main corollary gained from the analysis of the thermal equilibrium regime suggests that one-loop calculations of the presented models are not sufficient to make a definite conclusion about the stability of fixed points. We also show that critical exponents are drastically changed as a result of the turbulent background and critical fluctuations are in fact destroyed by the developed turbulence fluctuations. The scaling exponent of effective viscosity is calculated and agrees with expected value 4 /3 .

  2. Superfluid phase transition with activated velocity fluctuations: Renormalization group approach.

    PubMed

    Dančo, Michal; Hnatič, Michal; Komarova, Marina V; Lučivjanský, Tomáš; Nalimov, Mikhail Yu

    2016-01-01

    A quantum field model that incorporates Bose-condensed systems near their phase transition into a superfluid phase and velocity fluctuations is proposed. The stochastic Navier-Stokes equation is used for a generation of the velocity fluctuations. As such this model generalizes model F of critical dynamics. The field-theoretic action is derived using the Martin-Siggia-Rose formalism and path integral approach. The regime of equilibrium fluctuations is analyzed within the perturbative renormalization group method. The double (ε,δ)-expansion scheme is employed, where ε is a deviation from space dimension 4 and δ describes scaling of velocity fluctuations. The renormalization procedure is performed to the leading order. The main corollary gained from the analysis of the thermal equilibrium regime suggests that one-loop calculations of the presented models are not sufficient to make a definite conclusion about the stability of fixed points. We also show that critical exponents are drastically changed as a result of the turbulent background and critical fluctuations are in fact destroyed by the developed turbulence fluctuations. The scaling exponent of effective viscosity is calculated and agrees with expected value 4/3. PMID:26871026

  3. Group B Streptococcal Infection and Activation of Human Astrocytes

    PubMed Central

    Stoner, Terri D.; Weston, Thomas A.; Trejo, JoAnn; Doran, Kelly S.

    2015-01-01

    Background Streptococcus agalactiae (Group B Streptococcus, GBS) is the leading cause of life-threatening meningitis in human newborns in industrialized countries. Meningitis results from neonatal infection that occurs when GBS leaves the bloodstream (bacteremia), crosses the blood-brain barrier (BBB), and enters the central nervous system (CNS), where the bacteria contact the meninges. Although GBS is known to invade the BBB, subsequent interaction with astrocytes that physically associate with brain endothelium has not been well studied. Methodology/Principal Findings We hypothesize that human astrocytes play a unique role in GBS infection and contribute to the development of meningitis. To address this, we used a well- characterized human fetal astrocyte cell line, SVG-A, and examined GBS infection in vitro. We observed that all GBS strains of representative clinically dominant serotypes (Ia, Ib, III, and V) were able to adhere to and invade astrocytes. Cellular invasion was dependent on host actin cytoskeleton rearrangements, and was specific to GBS as Streptococcus gordonii failed to enter astrocytes. Analysis of isogenic mutant GBS strains deficient in various cell surface organelles showed that anchored LTA, serine-rich repeat protein (Srr1) and fibronectin binding (SfbA) proteins all contribute to host cell internalization. Wild-type GBS also displayed an ability to persist and survive within an intracellular compartment for at least 12 h following invasion. Moreover, GBS infection resulted in increased astrocyte transcription of interleukin (IL)-1β, IL-6 and VEGF. Conclusions/Significance This study has further characterized the interaction of GBS with human astrocytes, and has identified the importance of specific virulence factors in these interactions. Understanding the role of astrocytes during GBS infection will provide important information regarding BBB disruption and the development of neonatal meningitis. PMID:26030618

  4. Microbial Hydroxylation of 1,4-Cineole

    PubMed Central

    Rosazza, John P. N.; Steffens, James J.; Sariaslani, F. Sima; Goswami, Animesh; Beale, John M.; Reeg, Scot; Chapman, Robert

    1987-01-01

    Microorganisms were examined for their potential to hydroxylate the oxygenated monoterpene 1,4-cineole. Using gas chromatography and thin-layer chromatography, screening experiments revealed that hydroxylation at position 2 was the most commonly observed microbial transformation reaction. In most microorganisms, the predominant alcohol metabolite was the 2-endo-alcohol isomer. Preparative-scale incubations were conducted in order to isolate and characterize microbial transformation products by comparison of proton nuclear magnetic resonance, mass spectrometry, and chromatography profiles with those of cineole standards. Streptomyces griseus yielded 8-hydroxy-1,4-cineole as the major hydroxylation product together with 2-exo- and 2-endo-hydroxy-1,4-cineoles. PMID:16347465

  5. Neodymium Fluorescence Quenching by Hydroxyl Groups in Phosphate Laser Glasses

    SciTech Connect

    Ehrmann, P R; Carlson, K; Campbell, J H; Click, C A; Brow, R K

    2003-09-02

    Non-radiative losses due to OH fluorescence quenching of the Nd{sup 3+} {sup 4}F{sub 3/2} state are quantified over a range of OH concentrations from 4 x 10{sup 18}/cm{sup 3} to 4 x 10{sup 20}/cm{sup 3} and Nd doping levels from 0.4 to 9 x 10{sup 20}/cm{sup 3} in two K{sub 2}O-MgO-Al{sub 2}O{sub 3}-P{sub 2}O{sub 5} metaphosphate glasses having different K/Mg ratios ({approx}1/1 and 2/1). The quenching rate is found to vary linearly with the Nd and OH concentrations as predicted by Forster-Dexter theory. However, in contrast to theory the OH quenching rate extrapolates to a non-zero value at low Nd{sup 3+} doping levels. It is proposed that at low Nd{sup 3+} concentrations the OH is correlated with Nd sites in the glass. The quenching strength of OH on a per ion basis is found to be weak compared to other common transition metal impurities (e.g. Fe{sup 2+}, Co{sup 2+}, Ni{sup 2+}, Cu{sup 2+}). Nevertheless, OH dominates the Nd quenching in phosphate glass because under most processing conditions OH is present at concentrations 10{sup 2} to 10{sup 3} greater than transition metal ion impurities. A correlation of the quenching strength of OH and common metal impurity ions with the degree of spectral overlap of the impurity absorption bands and the four {sup 4}F{sub 3/2} to {sup 4}I{sub J} transitions shows good agreement.

  6. BRAIN REWARD ACTIVITY TO MASKED IN-GROUP SMILING FACES PREDICTS FRIENDSHIP DEVELOPMENT

    PubMed Central

    Chen, Pin-Hao A.; Whalen, Paul J.; Freeman, Jonathan B.; Taylor, James M.; Heatherton, Todd F.

    2015-01-01

    This study examined whether neural responses in the ventral striatum (VS) to in-group facial expressions—presented without explicit awareness—could predict friendship patterns in newly arrived individuals from China six months later. Individuals who initially showed greater VS activity in response to in-group happy expressions during functional neuroimaging later made considerably more in-group friends, suggesting that VS activity might reflect reward processes that drive in-group approach behaviors. PMID:26185595

  7. Reaction Mechanism of the Bicopper Enzyme Peptidylglycine α-Hydroxylating Monooxygenase*

    PubMed Central

    Abad, Enrique; Rommel, Judith B.; Kästner, Johannes

    2014-01-01

    Peptidylglycine α-hydroxylating monooxygenase is a noninteracting bicopper enzyme that stereospecifically hydroxylates the terminal glycine of small peptides for its later amidation. Neuroendocrine messengers, such as oxytocin, rely on the biological activity of this enzyme. Each catalytic turnover requires one oxygen molecule, two protons from the solvent, and two electrons. Despite this enzyme having been widely studied, a consensus on the reaction mechanism has not yet been found. Experiments and theoretical studies favor a pro-S abstraction of a hydrogen atom followed by the rebinding of an OH group. However, several hydrogen-abstracting species have been postulated; because two protons are consumed during the reaction, several protonation states are available. An electron transfer between the copper atoms could play a crucial role for the catalysis as well. This leads to six possible abstracting species. In this study, we compare them on equal footing. We perform quantum mechanics/molecular mechanics calculations, considering the glycine hydrogen abstraction. Our results suggest that the most likely mechanism is a protonation of the abstracting species before the hydrogen abstraction and another protonation as well as a reduction before OH rebinding. PMID:24668808

  8. A soluble Bacillus cereus cytochrome P-450cin system catalyzes 1,4-cineole hydroxylations.

    PubMed Central

    Liu, W; Rosazza, J P

    1993-01-01

    A cytochrome P-450-dependent monooxygenase system that catalyzes the stereospecific hydroxylation of the monoterpene substrate 1,4-cineole was demonstrated in cell-free preparations of Bacillus cereus UI-1477. 1,4-Cineole hydroxylations were catalyzed by a 100,000 x g (1-h)-centrifuging soluble, hexane-inducible enzyme that activated and incorporated molecular oxygen into hydroxylated products; required NADH; was inhibited by SKF-525A, imidazole, metyrapone, and octylamine; and displayed a 452-nm peak in the carbon monoxide difference absorption spectrum. The constant 7:1 ratio of endo/exo alcohol products formed when 1,4-cineole was hydroxylated by normal cells, hexane-induced cells, and cell extracts suggested that a single enzyme designated cytochrome P-450cin was responsible for both reactions. PMID:8285692

  9. Synthesis and antiplasmodial activity of lycorine derivatives.

    PubMed

    Cedrón, Juan C; Gutiérrez, David; Flores, Ninoska; Ravelo, Angel G; Estévez-Braun, Ana

    2010-07-01

    Twenty seven lycorine derivatives were prepared and evaluated for their in vitro antimalarial activity against chloroquine-sensitive strains of Plasmodium falciparum. The best antiplasmodial activities were achieved with lycorine derivatives that present free hydroxyl groups at C-1 and C-2 or esterified as acetates or isobutyrates. The double bond C-2-C-3 is also important for the activity. Concerning to the antiplasmodial activity of the secolycorines, the higher values were obtained with the replacement of the methylenedioxy moiety by hydroxyl or acetate groups and with methyl substituent attached to the nitrogen atom.

  10. The role of peer groups in male and female adolescents' task values and physical activity.

    PubMed

    Yli-Piipari, Sami; Jaakkola, Timo; Liukkonen, Jarmo; Kiuru, Noona; Watt, Anthony

    2011-02-01

    The purpose of this longitudinal study was to examine the role of peer groups and sex in adolescents' task values and physical activity. The participants were 330 Finnish Grade 6 students (173 girls, 157 boys), who responded to questionnaires that assessed physical education task values during the spring semester (Time 1). Students' physical activity was assessed one year later (Time 2). The results indicated that adolescent peer groups were moderately homogeneous in terms of task values toward physical education and physical activity. Girls' peer groups were more homogeneous than those of boys in regards to utility and attainment values. Furthermore, the results for both girls and boys showed that particularly intrinsic task value typical for the peer group predicted group members' physical activity. The findings highlight the important role of peer group membership as a determinant of future physical activity. PMID:21526593

  11. Suppression of adipogenesis and obesity in high-fat induced mouse model by hydroxylated polymethoxyflavones.

    PubMed

    Lai, Ching-Shu; Ho, Min-Hau; Tsai, Mei-Ling; Li, Shiming; Badmaev, Vladimir; Ho, Chi-Tang; Pan, Min-Hsiung

    2013-10-30

    This study demonstrated that hydroxylated polymethoxyflavones (HPMFs) effectively and dose-dependently suppressed accumulation of lipid droplets in adipocytes by approximately 51-55%. Western blot analysis revealed that HPMFs markedly down-regulated adipogenesis-related transcription factors peroxisome proliferator-activated receptor (PPAR) γ and sterol regulatory element-binding protein (SREBP)-1c as well as downstream target fatty acid binding protein 2 (aP2), fatty acid synthase (FAS), and acetyl-CoA carboxylase (ACC). In addition, HPMFs also activated adenosine monophosphate-activated protein kinase (AMPK) signaling in 3T3-L1 adipocytes. In the early phase of adipogenesis, HPMF-treated preadipocytes displayed a delayed cell cycle entry into G2/M phase at 24 h (35.5% for DMI group and 4.8% for 20 μg/mL HPMFs-treated group) after initiation of adipogenesis. Furthermore, administration of HPMFs (0.25 and 1%) decreased high-fat diet (HFD) induced weight gain (15.3 ± 3.9 g for HFD group, 10.3 ± 0.3 g and 7.9 ± 0.7 g for 0.25 and 1% HPMFs groups, respectively) and relative perigonadal, retroperitoneal, mesenteric fat weight in C57BL/6 mice. Administration of HPMFs reduced serum levels of aspartate aminotransferase (GOT), alanine aminotransferase (GPT), triglycerides (TG), and total cholesterol (T-cho). The results suggested that HPMFs may have a potential benefit in preventing obesity. PMID:24089698

  12. Horseradish peroxidase catalyzed hydroxylations: mechanistic studies.

    PubMed

    Dordick, J S; Klibanov, A M; Marletta, M A

    1986-05-20

    The hydroxylation of phenol to hydroquinone and catechol in the presence of dihydroxyfumaric acid and oxygen catalyzed by horseradish peroxidase was studied under conditions where the product yield was high and the side reactions were minimal. The reaction is partially uncoupled with a molar ratio of dihydroxyfumaric acid consumed to hydroxylated products of 12:1. Hydrogen peroxide does not participate in the reaction as evidenced by the lack of effect of catalase and by the direct addition of hydrogen peroxide. Conversely, superoxide and hydroxyl radicals are involved as their scavengers are potent inhibitors. Experiments were all consistent with the involvement of compound III (oxygenated ferrous complex) of peroxidase in the reaction. Compound III is stable in the presence of phenol alone but decomposes rapidly in the presence of both phenol and dihydroxyfumaric acid with the concomitant formation of product. Therefore, phenol and dihydroxyfumaric acid must be present with compound III in order for the hydroxylation reaction to occur. A mechanism consistent with the experimental results is proposed. PMID:3718931

  13. Endogenous released ascorbic acid suppresses ethanol-induced hydroxyl radical production in rat striatum.

    PubMed

    Huang, Mei; Liu, Wen; Li, Qiang; Wu, Chun Fu

    2002-07-19

    Previous studies have shown that acute systemic administration of ethanol induced ascorbic acid release in the striatum. However, the pharmacological implications of ethanol-induced striatal ascorbic acid release are unclear. In the present study, ethanol-induced extracellular changes of ascorbic acid and hydroxyl radical levels were detected in rat striatum by using brain microdialysis coupled to high-performance liquid chromatography with electrochemical detection. It was found that both in male and female rats, ethanol (3.0 g/kg, i.p.) increased striatal ascorbic acid release in the first 60 min after ethanol administration. Meanwhile, the extracellular hydroxyl radical levels, detected as 2,3- and 2,5-DHBA, were significantly decreased. However, when the ascorbic acid levels returned to the baseline, hydroxyl radical levels rebounded. Administration of DL-fenfluramine (20 mg/kg, i.p.) had no effect on the basal levels of ascorbic acid and hydroxyl radical, but significantly blocked ethanol-induced ascorbic acid release and increased hydroxyl radical levels significantly. Exogenous administration of ascorbic acid (20 mg/kg, s.c.) increased the extracellular levels of ascorbic acid in the striatum, and inhibited the increase of 2,3- and 2,5-DHBA in DL-fenfluramine plus ethanol group. These results provide first evidence that release of endogenous ascorbic acid in the striatum plays an important role in preventing oxidative stress by trapping hydroxyl radical in the central nervous system.

  14. Mechanism of N-hydroxylation catalyzed by flavin-dependent monooxygenases.

    PubMed

    Badieyan, Somayesadat; Bach, Robert D; Sobrado, Pablo

    2015-02-20

    Aspergillus fumigatus siderophore (SidA), a member of class B flavin-dependent monooxygenases, was selected as a model system to investigate the hydroxylation mechanism of heteroatom-containing molecules by this group of enzymes. SidA selectively hydroxylates ornithine to produce N(5)-hydroxyornithine. However, SidA is also able to hydroxylate lysine with lower efficiency. In this study, the hydroxylation mechanism and substrate selectivity of SidA were systematically studied using DFT calculations. The data show that the hydroxylation reaction is initiated by homolytic cleavage of the O-O bond in the C(4a)-hydroperoxyflavin intermediate, resulting in the formation of an internal hydrogen-bonded hydroxyl radical (HO(•)). As the HO(•) moves to the ornithine N(5) atom, it rotates and donates a hydrogen atom to form the C(4a)-hydroxyflavin. Oxygen atom transfer yields an aminoxide, which is subsequently converted to hydroxylamine via water-mediated proton shuttling, with the water molecule originating from dehydration of the C(4a)-hydroxyflavin. The selectivity of SidA for ornithine is predicted to be the result of the lower energy barrier for oxidation of ornithine relative to that of lysine (16 vs 24 kcal/mol, respectively), which is due to the weaker stabilizing hydrogen bond between the incipient HO(•) and O3' of the ribose ring of NADP(+) in the transition state for lysine.

  15. The Creation and Physiological Relevance of Divergent Hydroxylation Patterns in the Flavonoid Pathway

    PubMed Central

    Halbwirth, Heidi

    2010-01-01

    Flavonoids and biochemically-related chalcones are important secondary metabolites, which are ubiquitously present in plants and therefore also in human food. They fulfill a broad range of physiological functions in planta and there are numerous reports about their physiological relevance for humans. Flavonoids have in common a basic C6-C3-C6 skeleton structure consisting of two aromatic rings (A and B) and a heterocyclic ring (C) containing one oxygen atom, whereas chalcones, as the intermediates in the formation of flavonoids, have not yet established the heterocyclic C-ring. Flavonoids are grouped into eight different classes, according to the oxidative status of the C-ring. The large number of divergent chalcones and flavonoid structures is from the extensive modification of the basic molecules. The hydroxylation pattern influences physiological properties such as light absorption and antioxidative activity, which is the base for many beneficial health effects of flavonoids. In some cases antiinfective properties are also effected. PMID:20386656

  16. Independent and Small Group Activities for Social Studies in the Primary Grades.

    ERIC Educational Resources Information Center

    Ball, Barbara; And Others

    A teachers' guide for social studies, this manual stresses geography curriculum and activities for the primary grades. It is suggested that a teacher work with one group while the other children work individually. Children first work independently for a team, and then progress to less structured small group activities. Positive reinforcement by…

  17. The Effect of Science Activities on Concept Acquisition of Age 5-6 Children Groups

    ERIC Educational Resources Information Center

    Dogru, Mustafa; Seker, Fatih

    2012-01-01

    Present research aims to determine the effect of science activities on concept development of preschool period age 5-6 children groups. Parallel to research objective, qualitative research pattern has been the selected method. Study group comprises of collectively 48 children from 5-6 age group attending to a private education institution in city…

  18. Similar barriers and facilitators to physical activity across different clinical groups experiencing lower limb spasticity.

    PubMed

    Hundza, Sandra; Quartly, Caroline; Kim, Jasmine M; Dunnett, James; Dobrinsky, Jill; Loots, Iris; Choy, Kim; Chow, Brayley; Hampshire, Alexis; Temple, Viviene A

    2016-07-01

    Purpose Given the importance of physical activity in maintaining health and wellness, an improved understanding of physical activity patterns across different clinical populations is required. This study examines the facilitators for, and barriers to, participation in physical activity across multiple contexts for three clinical groups with chronic lower limb spasticity (individuals with stroke, multiple sclerosis and incomplete spinal cord injury). Method This cross-sectional study employed quantitative measures for spasticity, ankle range of motion, pain, falls, cognition, mobility, and physical activity as well as qualitative semi-structured interviews. Results There were similar impairments in body functions and structures and limitations in activities across the clinical groups. These impairments and limitations negatively impacted participation in physical activity, which was low. Environmental and personal factors exacerbated or mitigated the limiting effects of body functions and structures and activities on physical activity in many areas of life. Conclusions In this population, participation in physical activity includes activities such as housework which are different than what is typically considered as physical activity. Further, the presence of similar barriers and facilitators across the groups suggests that support and services to promote valued forms of physical activity could be organised and delivered based on limitations in mobility and functioning rather than clinical diagnosis. Implications for rehabilitation Physical activity is of utmost importance in maintaining health and wellness in clinical populations. This research highlights the desired and actual physical activity for these populations can look different than what may traditionally be considered as physical activity (e.g. housework is not typically considered participation physical activity). Therefore, rehabilitation interventions need to be directly designed to enhance clients

  19. Group cognitive behavioural therapy and group recreational activity for adults with autism spectrum disorders: A preliminary randomized controlled trial

    PubMed Central

    Plenty, Stephanie; Bejerot, Susanne

    2014-01-01

    Although adults with autism spectrum disorder are an increasingly identified patient population, few treatment options are available. This preliminary randomized controlled open trial with a parallel design developed two group interventions for adults with autism spectrum disorders and intelligence within the normal range: cognitive behavioural therapy and recreational activity. Both interventions comprised 36 weekly 3-h sessions led by two therapists in groups of 6–8 patients. A total of 68 psychiatric patients with autism spectrum disorders participated in the study. Outcome measures were Quality of Life Inventory, Sense of Coherence Scale, Rosenberg Self-Esteem Scale and an exploratory analysis on measures of psychiatric health. Participants in both treatment conditions reported an increased quality of life at post-treatment (d = 0.39, p < 0.001), with no difference between interventions. No amelioration of psychiatric symptoms was observed. The dropout rate was lower with cognitive behavioural therapy than with recreational activity, and participants in cognitive behavioural therapy rated themselves as more generally improved, as well as more improved regarding expression of needs and understanding of difficulties. Both interventions appear to be promising treatment options for adults with autism spectrum disorder. The interventions’ similar efficacy may be due to the common elements, structure and group setting. Cognitive behavioural therapy may be additionally beneficial in terms of increasing specific skills and minimizing dropout. PMID:24089423

  20. Group cognitive behavioural therapy and group recreational activity for adults with autism spectrum disorders: a preliminary randomized controlled trial.

    PubMed

    Hesselmark, Eva; Plenty, Stephanie; Bejerot, Susanne

    2014-08-01

    Although adults with autism spectrum disorder are an increasingly identified patient population, few treatment options are available. This preliminary randomized controlled open trial with a parallel design developed two group interventions for adults with autism spectrum disorders and intelligence within the normal range: cognitive behavioural therapy and recreational activity. Both interventions comprised 36 weekly 3-h sessions led by two therapists in groups of 6-8 patients. A total of 68 psychiatric patients with autism spectrum disorders participated in the study. Outcome measures were Quality of Life Inventory, Sense of Coherence Scale, Rosenberg Self-Esteem Scale and an exploratory analysis on measures of psychiatric health. Participants in both treatment conditions reported an increased quality of life at post-treatment (d = 0.39, p < 0.001), with no difference between interventions. No amelioration of psychiatric symptoms was observed. The dropout rate was lower with cognitive behavioural therapy than with recreational activity, and participants in cognitive behavioural therapy rated themselves as more generally improved, as well as more improved regarding expression of needs and understanding of difficulties. Both interventions appear to be promising treatment options for adults with autism spectrum disorder. The interventions' similar efficacy may be due to the common elements, structure and group setting. Cognitive behavioural therapy may be additionally beneficial in terms of increasing specific skills and minimizing dropout.

  1. Group II p21-activated kinases as therapeutic targets in gastrointestinal cancer

    PubMed Central

    Shao, Yang-Guang; Ning, Ke; Li, Feng

    2016-01-01

    P21-activated kinases (PAKs) are central players in various oncogenic signaling pathways. The six PAK family members are classified into group I (PAK1-3) and group II (PAK4-6). Focus is currently shifting from group I PAKs to group II PAKs. Group II PAKs play important roles in many fundamental cellular processes, some of which have particular significance in the development and progression of cancer. Because of their important functions, group II PAKs have become popular potential drug target candidates. However, few group II PAKs inhibitors have been reported, and most do not exhibit satisfactory kinase selectivity and “drug-like” properties. Isoform- and kinase-selective PAK inhibitors remain to be developed. This review describes the biological activities of group II PAKs, the importance of group II PAKs in the development and progression of gastrointestinal cancer, and small-molecule inhibitors of group II PAKs for the treatment of cancer. PMID:26811660

  2. 4-Substituted-2-Methoxyphenol: Suitable Building Block to Prepare New Bioactive Natural-like Hydroxylated Biphenyls

    PubMed Central

    Dettori, Maria Antonietta; Fabbri, Davide; Pisano, Marina; Rozzo, Carla; Palmieri, Giuseppe; Dessµ, Alessandro; Dallocchio, Roberto; Delogu, Giovanna

    2015-01-01

    A small collection of eugenol- and curcumin-analog hydroxylated biphenyls was prepared by straightforward methods starting from natural 4-substituted-2-methoxyphenols and their antitumoral activity was evaluated in vitro. Two curcumin-biphenyl derivatives showed interesting growth inhibitory activities on different malignant melanoma cell lines with IC50 ranging from 13 to 1 µM. Preliminary molecular modeling studies were carried out to evaluate conformations and dihedral angles suitable for antiproliferative activity in hydroxylated biphenyls bearing a side aliphatic chain. PMID:26074750

  3. Tunable photoluminescence and spectrum split from fluorinated to hydroxylated graphene

    NASA Astrophysics Data System (ADS)

    Gong, Peiwei; Wang, Jinqing; Sun, Weiming; Wu, Di; Wang, Zhaofeng; Fan, Zengjie; Wang, Honggang; Han, Xiuxun; Yang, Shengrong

    2014-02-01

    Tunable control over the functionalization of graphene is significantly important to manipulate its structure and optoelectronic properties. Yet the chemical inertness of this noble carbon material poses a particular challenge for its decoration without forcing reaction conditions. Here, a mild, operationally simple and controllable protocol is developed to synthesize hydroxylated graphene (HOG) from fluorinated graphene (FG). We successfully demonstrate that under designed alkali environment, fluorine atoms on graphene framework are programmably replaced by hydroxyl groups via a straightforward substitution reaction pathway. Element constituent analyses confirm that homogeneous C-O bonds are successfully grafted on graphene. Rather different from graphene oxide, the photoluminescence (PL) emission spectrum of the obtained HOG becomes split when excited with UV radiation. More interestingly, such transformation from FG facilitates highly tunable PL emission ranging from greenish white (0.343, 0.392) to deep blue (0.156, 0.094). Additionally, both experimental data and density function theory calculation indicate that the chemical functionalization induced structural rearrangement is more important than the chemical decoration itself in tuning the PL emission band tail and splitting energy gaps. This work not only presents a new way to effectively fabricate graphene derivatives with tunable PL performance, but also provides an enlightening insight into the PL origin of graphene related materials.Tunable control over the functionalization of graphene is significantly important to manipulate its structure and optoelectronic properties. Yet the chemical inertness of this noble carbon material poses a particular challenge for its decoration without forcing reaction conditions. Here, a mild, operationally simple and controllable protocol is developed to synthesize hydroxylated graphene (HOG) from fluorinated graphene (FG). We successfully demonstrate that under designed

  4. Hydroxyl radical formation in skeletal muscle of rats with glucocorticoid-induced myopathy.

    PubMed

    Konno, Shingo

    2005-05-01

    Steroid myopathy is a well-known adverse effect of glucocorticoids that causes muscle weakness and atrophy; however, its pathogenic mechanism is still unclear. Recently, oxidative stress was reported to contribute to steroid myopathy, but there is no report that actually attempts to measure hydroxyl radical. I developed an animal model of steroid myopathy in rat with dexamethasone (9-Fluoro-11beta,17, 21-trihydroxy-16alpha-methylpregna-1,4-diene-3,20-dione), and measured hydroxyl radical using the salicylate trapping method. There was significant dose-dependent relation between both 2,5- and 2,3-dihydroxybenzoic acids and dexamethasone in the treated group, compared to the control group. These results suggest that hydroxyl radical plays a role in the pathogenesis of steroid myopathy.

  5. The physical activity profiles of South Asian ethnic groups in England

    PubMed Central

    Bhatnagar, Prachi; Townsend, Nick; Shaw, Alison; Foster, Charlie

    2016-01-01

    Background To identify what types of activity contribute to overall physical activity in South Asian ethnic groups and how these vary according to sex and age. We used the White British ethnic group as a comparison. Methods Self-reported physical activity was measured in the Health Survey for England 1999 and 2004, a nationally representative, cross-sectional survey that boosted ethnic minority samples in these years. We merged the two survey years and analysed data from 19 476 adults. The proportions of total physical activity achieved through walking, housework, sports and DIY activity were calculated. We stratified by sex and age group and used analysis of variances to examine differences between ethnic groups, adjusted for the socioeconomic status. Results There was a significant difference between ethnic groups for the contributions of all physical activity domains for those aged below 55 years, with the exception of walking. In women aged 16–34 years, there was no significant difference in the contribution of walking to total physical activity (p=0.38). In the 35–54 age group, Bangladeshi males have the highest proportion of total activity from walking (30%). In those aged over 55 years, the proportion of activity from sports was the lowest in all South Asian ethnic groups for both sexes. Conclusions UK South Asians are more active in some ways that differ, by age and sex, from White British, but are similarly active in other ways. These results can be used to develop targeted population level interventions for increasing physical activity levels in adult UK South Asian populations. PMID:26677257

  6. Comets: production mechanisms of hydroxyl and hydrogen halos.

    PubMed

    Delsemme, A H

    1971-06-11

    The brightness dependence on the heliocentric distance that has been observed for the hydrogen and the hydroxyl halos of comet 1969g can be quantitatively explained by a three-step process: the vaporization of the water snows, the photodissociation of the water molecule into the ground states of hydrogen and hydroxyl, and the photoexcitation of hydrogen and hydroxyl by a fluorescence mechanism.

  7. What is the active species of cytochrome P450 during camphor hydroxylation? QM/MM studies of different electronic states of compound I and of reduced and oxidized iron-oxo intermediates.

    PubMed

    Altun, Ahmet; Shaik, Sason; Thiel, Walter

    2007-07-25

    We have investigated C-H hydroxylation of camphor by Compound I (Cpd I) of cytochrome P450cam in different electronic states and by its one-electron reduced and oxidized forms, using QM/MM calculations in the native protein/solvent environment. Cpd I species with five unpaired electrons (pentaradicaloids) are ca. 12 kcal/mol higher in energy than the ground state Cpd I species with three unpaired electrons (triradicaloids). The H-abstraction transition states of pentaradicaloids lie ca. 21 (9) kcal/mol above the triradicaloid (pentaradicaloid) reactants. Hydroxylation via pentaradicaloids is thus facile provided that they can react before relaxing to the ground-state triradicaloids. Excited states of Cpd I with an Fe(V)-oxo moiety lie more than 20 kcal/mol above the triradicaloid ground state in single-point gas-phase calculations, but these electronic configurations are not stable upon including the point-charge protein environment which causes SCF convergence to the triradicaloid ground state. One-electron reduced species (Cpd II) show sluggish reactivity compared with Cpd I in agreement with experimental model studies. One-electron oxidized species are more reactive than Cpd I but seem too high in energy to be accessible. The barriers to hydrogen abstraction for the various forms of Cpd I are generally not affected much by the chosen protonation states of the Asp297 and His355 residues near the propionate side chains of the heme or by the appearance of radical character at Asp297, His355, or the propionates. PMID:17595079

  8. Hydroxyl radical generation by red tide algae.

    PubMed

    Oda, T; Akaike, T; Sato, K; Ishimatsu, A; Takeshita, S; Muramatsu, T; Maeda, H

    1992-04-01

    The unicellular marine phytoplankton Chattonella marina is known to have toxic effects against various living marine organisms, especially fishes. However, details of the mechanism of the toxicity of this plankton remain obscure. Here we demonstrate the generation of superoxide and hydroxyl radicals from a red tide unicellular organism, C. marina, by using ESR spectroscopy with the spin traps 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) and N-t-butyl-alpha-phenylnitrone (PBN), and by using the luminol-enhanced chemiluminescence response. The spin-trapping assay revealed productions of spin adduct of superoxide anion (O2-) (DMPO-OOH) and that of hydroxyl radical (.OH) (DMPO-OH) in the algal suspension, which was not observed in the ultrasonic-ruptured suspension. The addition of superoxide dismutase (500 U/ml) almost completely inhibited the formation of both DMPO-OOH and DMPO-OH, and carbon-centered radicals were generated with the disappearance of DMPO-OH after addition of 5% dimethyl sulfoxide (Me2SO) and 5% ethanol. Furthermore, the generation of methyl and methoxyl radicals, which are thought to be produced by the reaction of hydroxyl radical and Me2SO under aerobic condition, was identified using spin trapping with a combination of PBN and Me2SO. Luminol-enhanced chemiluminescence assay also supported the above observations. These results clearly indicate that C. marina generates and releases the superoxide radical followed by the production of hydroxyl radical to the surrounding environment. The velocity of superoxide generation by C. marina was about 100 times faster than that by mammalian phagocytes per cell basis. The generation of oxygen radical is suggested to be a pathogenic principle in the toxication of red tide to susceptible aquaculture fishes and may be directly correlated with the coastal pollution by red tide.

  9. Measuring enjoyment of physical activity in older adults: invariance of the physical activity enjoyment scale (paces) across groups and time

    PubMed Central

    2011-01-01

    The purpose of this study was to validate the Physical Activity Enjoyment Scale (PACES) in a sample of older adults. Participants within two different exercise groups were assessed at two time points, 6 months apart. Group and longitudinal invariance was established for a novel, 8-item version of the PACES. The shortened, psychometrically sound measure provides researchers and practitioners an expedited and reliable instrument for assessing the enjoyment of physical activity. PMID:21951520

  10. Comparison of Hemagglutination and Hemolytic Activity of Various Bacterial Clinical Isolates Against Different Human Blood Groups

    PubMed Central

    HRV, Rajkumar; Devaki, Ramakrishna

    2016-01-01

    Among the various pathogenic determinants shown by microorganisms hemagglutination and hemolysin production assume greater significance in terms of laboratory identification. This study evaluated the hemagglutination and hemolytic activity of various bacterial isolates against different blood groups. One hundred and fifty bacterial strains, isolated from clinical specimens like urine, pus, blood, and other body fluids were tested for their hemagglutinating and hemolytic activity against human A, B, AB, and O group red blood cells. Among the 150 isolates 81 were Escherichia coli, 18 were Klebsiella pneumoniae, 19 were Pseudomonas aeruginosa, 10 were Pseudomonas spp, six were Proteus mirabilis, and the rest 16 were Staphylococcus aureus. Nearly 85% of the isolates agglutinated A group cells followed by B and AB group (59.3% and 60.6% respectively). Least number of isolates agglutinated O group cells (38.0%). When the hemolytic activity was tested, out of these 150 isolates 79 (52.6%) hemolyzed A group cells, 61 (40.6%) hemolyzed AB group cells, 46 (30.6%) hemolyzed B group cells, and 57 (38.6%) isolates hemolyzed O group cells. Forty-six percent of the isolates exhibited both hemagglutinating and hemolytic property against A group cells, followed by B and AB group cells (28.6% and 21.3% respectively). Least number of isolates i.e., 32 (21.3%) showed both the properties against O group cells. The isolates showed wide variation in their hemagglutination and hemolytic properties against different combinations of human blood group cells. The study highlights the importance of selection of the type of cells especially when human RBCs are used for studying the hemagglutination and hemolytic activity of bacterial isolates because these two properties are considered as characteristic of pathogenic strains. PMID:27014523

  11. Investigating Hydroxyl at Asteroid 951 Gaspra

    NASA Astrophysics Data System (ADS)

    Granahan, James C.

    2015-11-01

    Recent investigations [Granahan, 2011; 2014] of Galileo Near Infrared Mapping Spectrometer (NIMS) observations of asteroid 951 Gaspra have detected an infrared absorption feature near 2.8 micrometers. These were detected in NIMS data acquired by the Galileo spacecraft on October 29, 1991 at wavelengths ranging from 0.7 - 5.2 micrometers [Carlson et al., 1992]. This abstract presents a summary of the investigation to identify the material creating the 2.8 micrometer spectral absorption feature. The current best match for the observed 951 Gaspra feature is the phyllosilicate bound hydroxyl signature present in a thermally desiccated QUE 99038 carbonaceous chondrite as measured by Takir et al. [2013].The 951 Gaspra absorption feature has been compared to a variety of hydroxyl bearing signatures. Many phyllosilicates, hydroxyl bearing minerals, have absorption minima at different positions (2.7 or 2.85 micrometers). It also differs from similar absorptions in a potential R chondrite analog, LAP 04840. The spectra LAP 04840 has a 2.7 micrometer feature due to biotite and a 2.9 micrometer feature due to adsorbed water [Klima et al., 2007]. 2.8 micrometer absorption minima have been found for adsorbed hydroxyl on the Moon [McCord et al., 2011] and various carbonaceous chondrites [Calvin and King, 1997; Takir et al., 2013]. The best match, with a minimum Euclidean distance difference to the 951 Gaspra feature, is found in the spectrum of QUE 99038 [Takir et al., 2013]. This spectrum is the product of an infrared measurement of a sample that had its adsorbed water baked off and removed in a vacuum chamber. The remaining hydroxyl in the sample belongs to a mixture of phyllosilicates dominated by the presence of cronstedtite.References: Calvin, W. M., and T. V. King (1997), Met. Planet. Sci., 32, 693-702. Carlson, R. W., et al. (1992), Bull. American Astro. Soc., 24, 932. Granahan, J. C. (2011), Icarus, 213, 265-272. Granahan, J. C. (2014), 45th LPSC, #1092. Klima, R., C. et

  12. Active Learning in the Classroom: The Use of Group Role Plays.

    ERIC Educational Resources Information Center

    Kitzerow, Phyllis

    1990-01-01

    Describes group role-playing activities that have been used to teach about education, criminology, and sex roles. Suggests that role play helps students to absorb and retain many of the insights about the issues involved. (DB)

  13. Carboxylate groups play a major role in antitumor activity of Ganoderma applanatum polysaccharide.

    PubMed

    Sun, Xiaobo; Zhao, Chen; Pan, Wei; Wang, Jinping; Wang, Weijun

    2015-06-01

    In this paper, the structure difference between the polysaccharides isolated from fruit bodies (FGAP) and submerged fermentation system (SGAP) of Ganoderma applanatum was investigated by means of GPC, HPLC and IR, respectively. And their antitumor activities were evaluated against Sarcoma 180 in vivo. The results showed that FGAP and SGAP were typical polysaccharides with different molecular weights, monosaccharide components, and functional groups. Closely related to the distinct structures, FGAP exhibited a better antitumor activity than SGAP. Moreover, since FGAP contained carboxylate groups rather than SGAP, such groups were chemically introduced into SGAP (CSGAP) by carboxymethylation in order to identify their contribution to antitumor activity. The results demonstrated that the inhibition of CSGAP against Sarcoma 180 in vivo was significantly enhanced by comparison to the native SGAP and even higher than that of FGAP, suggesting that the carboxylate groups played a major role in antitumor activity of G. applanatum polysaccharide.

  14. Protective effects of hydroxybenzoic acids and their esters on cell damage induced by hydroxyl radicals and hydrogen peroxides.

    PubMed

    Masaki, H; Okamoto, N; Sakaki, S; Sakurai, H

    1997-04-01

    The purpose of this study was to evaluate the hydroxyl radical scavenging activities of hydroxybenzoic acids and their esters from both chemical and biological aspects. These activities of hydroxybenzoic acids and their related compounds were estimated by ESR-spin trapping method, in which 3,4,5-trihydroxybenzoic acid and its ethyl and propyl esters showed the highest activities as estimated by IC50 value (50% inhibition concentration of hydroxyl radicals generated in the system): 78.04 +/- 11.23, 95.95 +/- 2.64, and 86.46 +/- 2.31 microM, respectively. In addition, 3,4,5-trihydroxybenzoic acid (gallic acid) at a concentration of 25 microM, protected against dermal fibroblast cell damage induced by H2O2, and enhanced the survival to 83.8 +/- 3.1%, in which the survival of control was 44.2 +/- 1.0%. Based on these results, the pretreatment effects of 3,4,5-trihydroxybenzoic acid n-alkyl esters on cell damage induced by H2O2 were examined. The survival of fibroblasts pretreated with the esters increased depending on the alkyl chain-length. Both C12 and C16 alkyl esters gave almost complete cell survival of 89.5 +/- 2.0% and 91.3 +/- 1.0%, respectively. The order of the protective effects of the compounds was in good agreement with that of their partition coefficients, suggesting that 3,4,5-trihydroxybenzoic acid alkyl esters are incorporated into fibroblasts, and thus prevent the cells from the toxicity caused by H2O2. In addition, an increase of intracellular peroxide formation in fibroblasts induced by UVA-irradiation, was suppressed to 2.27 +/- 0.41 nmol/10(4) cells by pretreatment with C16 alkyl ester at a concentration of 25 microM. Since 3,4,5-trihydroxybenzoic group has been demonstrated to possess a potent scavenging activity of hydroxyl radicals, this moiety was indicated to be important in preventing cell damage induced by UVA or H2O2: in turn, these produce hydroxyl radicals in the presence of trace metal ions such as iron and copper in cells.

  15. [7alpha-hydroxylation of steroid 5-olefins by mold fungi].

    PubMed

    Andriushina, V G; Druzhinina, A V; Iaderets, V V; Stytsenko, T S; Voĭshvillo, N E

    2010-01-01

    Hydroxylation activity of the mold fungi belonging to the orders Dothideales, Hypocreales, and Mucorales towards delta(5)-3beta-hydroxysteroids was studied. The fungi Bipolaris sorokiniana, Fusarium sp., and Rhizopus nigricans were able to introduce hydroxy group at position 7alpha; however, this ability was detected only at a low substrate load and with a low yield. A 7alpha-hydroxylase activity of the Curvularia lunata VKPM F-981 culture was shown for the first time. It was demonstrated that the studied strain was capable of stereo- and regioselective transformations of androstane 5-olefins at a load not less than 2 g/l. Conversion of pregnane steroids by this culture yielded both 7alpha and 11beta-hydroxy derivatives. The introduction of 7alpha-hydroxy group by this strain occurred concurrently with enzymatic hydrolysis of ester groups, which proceeded under mild conditions to give the corresponding alcohols in the cases of both 3-acetate of delta(5)-androstenes and mono- and triacetates of delta(5)-pregnenes.

  16. The Relationship between Students' Small Group Activities, Time Spent on Self-Study, and Achievement

    ERIC Educational Resources Information Center

    Kamp, Rachelle J. A.; Dolmans, Diana H. J. M.; van Berkel, Henk J. M.; Schmidt, Henk G.

    2012-01-01

    The purpose of this study was to investigate the relationship between the contributions students make to the problem-based tutorial group process as observed by their peers, self-study time and achievement. To that end, the Maastricht Peer Activity Rating Scale was administered to students participating in Problem-Based Learning tutorial groups.…

  17. DHPG Activation of Group 1 mGluRs in BLA Enhances Fear Conditioning

    ERIC Educational Resources Information Center

    Rudy, Jerry W.; Matus-Amat, Patricia

    2009-01-01

    Group 1 metabotropic glutamate receptors are known to play an important role in both synaptic plasticity and memory. We show that activating these receptors prior to fear conditioning by infusing the group 1 mGluR agonist, (R.S.)-3,5-dihydroxyphenylglycine (DHPG), into the basolateral region of the amygdala (BLA) of adult Sprague-Dawley rats…

  18. Need for Cognition and Active Information Search in Small Student Groups

    ERIC Educational Resources Information Center

    Curseu, Petru Lucian

    2011-01-01

    In a sample of 213 students organized in 44 groups this study tests the impact of need for cognition on active information search by using a multilevel analysis. The results show that group members with high need for cognition seek more advice in task related issues than those with low need for cognition and this pattern of information exchange is…

  19. 76 FR 72997 - Railroad Safety Advisory Committee (RSAC); Working Group Activity Update

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-28

    ... for additional language. The NPRM was published on January 12, 2011 (76 FR 2200), and the final rule... announcement of working group activities and status reports of December 7, 2010 (75 FR 76070). The 44th full..., 2006 (71 FR 50275), and was open for comment until October 23, 2006. The working group agreed...

  20. Hydroxyl radical mediated DNA base modification by manmade mineral fibres.

    PubMed Central

    Leanderson, P; Söderkvist, P; Tagesson, C

    1989-01-01

    Manmade mineral fibres (MMMFs) were examined for their ability to hydroxylate 2-deoxyguanosine (dG) to 8-hydroxydeoxyguanosine (8-OH-dG), a reaction that is mediated by hydroxyl radicals. It appeared that (1) catalase and the hydroxyl radical scavengers, dimethylsulphoxide and sodium benzoate, inhibited the hydroxylation, whereas Fe2+ and H2O2 potentiated it; (2) pretreatment of MMMFs with the iron chelator, deferoxamine, or with extensive heat (200-400 degrees C), attenuated the hydroxylation; (3) the hydroxylation obtained by various MMMFs varied considerably; (4) there was no apparent correlation between the hydroxylation and the surface area of different MMMFs, although increasing the surface area of a fibre by crushing it increased its hydroxylating capacity; and (5) there was good correlation between the hydroxylation of dG residues in DNA and the hydroxylation of pure dG in solution for the 16 different MMMFs investigated. These findings indicate that MMMFs cause a hydroxyl radical mediated DNA base modification in vitro and that there is considerable variation in the reactivity of different fibre species. The DNA modifying ability seems to depend on physical or chemical characteristics, or both, of the fibre. PMID:2765416

  1. Development of a Concise Synthesis of Ouabagenin and Hydroxylated Corticosteroid Analogues

    PubMed Central

    2016-01-01

    The natural product ouabagenin is a complex cardiotonic steroid with a highly oxygenated skeleton. This full account describes the development of a concise synthesis of ouabagenin, including the evolution of synthetic strategy to access hydroxylation at the C19 position of a steroid skeleton. In addition, approaches to install the requisite butenolide moiety at the C17 position are discussed. Lastly, methodology developed in this synthesis has been applied in the generation of novel analogues of corticosteroid drugs bearing a hydroxyl group at the C19 position. PMID:25594682

  2. Hydroxyl orientations in cellobiose and other polyhydroxy compounds – modeling versus experiment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Theoretical and experimental gas-phase studies of carbohydrates show that their hydroxyl groups are located in homodromic partial rings that resemble cooperative hydrogen bonds, albeit with long H…O distances and small O-H…O angles. On the other hand, anecdotal experience with disaccharide crystal ...

  3. DFT STUDY OF ALPHA-MALTOSE: INFLUENCE OF HYDROXYL ORIENTATIONS ON THE GLYCOSIDIC BOND

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The result of DFT geometry optimization of 68 unique alpha-maltose conformers at the B3LYP/6-311++G** level of theory is described. Particular attention is paid to the hydroxyl group rotational positions and their influence on the glycosidic bond dihedral angles. The orientation of lone pair elect...

  4. Group cohesion and between session homework activities predict self-reported cognitive-behavioral skill use amongst participants of SMART Recovery groups.

    PubMed

    Kelly, Peter J; Deane, Frank P; Baker, Amanda L

    2015-04-01

    SMART Recovery groups are cognitive-behaviorally oriented mutual support groups for individuals with addictions. The aim of the study was to assess the extent to which the quality of group facilitation, group cohesion and the use of between session homework activities contribute to self-rated use of cognitive-behavioral skills amongst group participants. Participants attending SMART Recovery groups in Australia completed a cross sectional survey (N=124). The survey included measures of cognitive and behavioral skill utilization, group cohesion, quality of group facilitation and a rating of how frequently participants leave group meetings with an achievable between session homework plan. On average, participants had been attending SMART Recovery meetings for 9 months. Participants were most likely to attend SMART Recovery for problematic alcohol use. Regression analyses indicated that group cohesion significantly predicted use of cognitive restructuring, but that only provision of homework at the end of each group session predicted self-reported behavioral activation. Both group cohesion and leaving a group with an achievable homework plan predicted participant use of cognitive behavioral skills. The concrete actions associated with homework activities may facilitate behavioral activation. There is a need for longitudinal research to examine the relationship between the utilization of cognitive and behavioral skills and participant outcomes (e.g. substance use, mental health) for people attending SMART Recovery groups. PMID:25535099

  5. Resident-Assisted Montessori Programming (Ramp): Training Persons with Dementia to Serve as Group Activity Leaders

    ERIC Educational Resources Information Center

    Camp, Cameron J.; Skrajner, Michael J.

    2004-01-01

    Purpose: The purpose of this study was to determine the effects of an activity implemented by means of Resident-Assisted Montessori Programming (RAMP). Design and Methods: Four persons with early-stage dementia were trained to serve as leaders for a small-group activity played by nine persons with more advanced dementia. Assessments of leaders'…

  6. Upper Elementary Boys' Participation during Group Singing Activities in Single-Sex and Coeducational Classes

    ERIC Educational Resources Information Center

    Bazzy, Zadda M.

    2010-01-01

    As boys in the upper elementary grades become increasingly influenced by peer pressure, many are less likely to participate in singing activities because singing is considered a "feminine" activity. The purpose of this research was to explore if there was an effect on upper elementary boys' level of participation during group singing activities…

  7. Taking It to the Classroom: Number Board Games as a Small Group Learning Activity

    ERIC Educational Resources Information Center

    Ramani, Geetha B.; Siegler, Robert S.; Hitti, Aline

    2012-01-01

    We examined whether a theoretically based number board game could be translated into a practical classroom activity that improves Head Start children's numerical knowledge. Playing the number board game as a small group learning activity promoted low-income children's number line estimation, magnitude comparison, numeral identification, and…

  8. What Do We Want Small Group Activities For? Voices from EFL Teachers in Japan

    ERIC Educational Resources Information Center

    Kato, Yoshitaka

    2016-01-01

    This paper discusses the fundamental issue of why small group activities are utilized in the language learning classroom. Although these activities have gained popularity in the field of Teaching English as a Second Language (TESL), supported by a sound theoretical base, few studies have so far examined the reasons why language teachers are…

  9. 75 FR 49913 - Active Duty Service Determinations For Civilian or Contractual Groups

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-16

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF DEFENSE Department of the Air Force Active Duty Service Determinations For Civilian or Contractual Groups SUMMARY: On... at Then `American Camp,' Now Named `Burma Camp,' Ghana' '' shall not be considered ``active...

  10. IMPORTANCE OF ACTIVATED CARBON'S OXYGEN SURFACE FUNCTIONAL GROUPS ON ELEMENTAL MERCURY ADSORPTION

    EPA Science Inventory

    The effect of varying physical and chemical properties of activated carbons on adsorption of elemental mercury [Hg(0)] was studied by treating two activated carbons to modify their surface functional groups and pore structures. Heat treatment (1200 K) in nitrogen (N2), air oxidat...

  11. ACTIVITY IN GALACTIC NUCLEI OF COMPACT GROUP GALAXIES IN THE LOCAL UNIVERSE

    SciTech Connect

    Sohn, Jubee; Lee, Myung Gyoon; Lee, Gwang-Ho; Hwang, Ho Seong; Lee, Jong Chul E-mail: mglee@astro.snu.ac.kr E-mail: hhwang@cfa.harvard.edu

    2013-07-10

    We study the nuclear activity of galaxies in local compact groups. We use a spectroscopic sample of 238 galaxies in 58 compact groups from the Sloan Digital Sky Survey data release 7 to estimate the fraction of active galactic nucleus (AGN) host galaxies in compact groups, and to compare it with those in cluster and field regions. We use emission-line ratio diagrams to identify AGN host galaxies and find that the AGN fraction of compact group galaxies is 17%-42% depending on the AGN classification method. The AGN fraction in compact groups is not the highest among the galaxy environments. This trend remains even if we use several subsamples segregated by galaxy morphology and optical luminosity. The AGN fraction for early-type galaxies decreases with increasing galaxy number density, but the fraction for late-type galaxies changes little. We find no mid-infrared detected AGN host galaxies in our sample of compact groups using Wide-field Infrared Survey Explorer data. These results suggest that the nuclear activity of compact group galaxies (mostly early types) is not strong because of lack of gas supply even though they may experience frequent galaxy-galaxy interactions and mergers that could trigger nuclear activity.

  12. The influence of sensor orientation on activity-based rate responsive pacing. Sensor Orientation Study Group.

    PubMed

    Theres, H; Philippon, F; Melzer, C; Combs, W; Prest-Berg, K

    1998-11-01

    Piezoelectric activity-based rate responsive pacemakers are commonly implanted with the sensor facing inward. This study was conducted to assess the safe and effective rate response of an activity-based rate responsive pacemaker implanted with the sensor facing outward. A comparison were made to a previously studied patient group with sensor facing inward. Patient and pacemaker data was collected at predischarge and 2-month follow-up. Two-minute hall walks in conjunction with programmer-assisted rate response assessment were utilized to standardize initial rate response parameter settings for both patient groups. At 2-month follow-up, sensor rate response to a stage 3 limited CAEP protocol was recorded. Adequate sensor rate response was achieved for both patient groups. No difference was noted in reported patient complications for both groups. A statistically significant difference in programmed rate response curve setting and activity threshold for the two groups was noted at 2-month follow-up. Adequate sensor rate response was achieved for a patient population implanted with an activity-based rate responsive pacemaker with sensor facing outward. In this orientation, one higher rate response curve setting and an activity threshold one value more sensitive were required on average when compared to the normal sensor orientation group. PMID:9826862

  13. Aromatic-Hydroxyl Interaction of a Lignin Model Compound on SBA-15, Present at Pyrolysis Temperatures

    SciTech Connect

    Kandziolka, III, Michael V.; Kidder, Michelle; Gill, Lance W.; Wu, Zili; Savara, Aditya Ashi

    2014-07-14

    An aromatic alpha-aryl ether compound (a benzyl phenyl ether analogue) was covalently grafted to mesoporous silica SBA-15, to create BPEa-SBA-15. The BPEa-SBA-15 was subjected to successive heating cycles up to 600 °C, with in situ monitoring by DRIFTS. It was found that the toluene moiety coordinates to SBA-15 surface silanol hydroxyl groups via an aromatic–hydroxyl interaction. This interaction is evidenced by a red-shift of the aromatic C–H stretches, as well as a red-shift and broadening of the surface hydroxyl O–H stretches, which are features characteristic of a hydrogen bond. These features remain present during heating until ~400 °C whereupon the ether linkage of BPEa-SBA-15 is cleaved, accompanied by loss of the toluene moiety.

  14. Aromatic-Hydroxyl Interaction of a Lignin Model Compound on SBA-15, Present at Pyrolysis Temperatures

    DOE PAGES

    Kandziolka, III, Michael V.; Kidder, Michelle; Gill, Lance W.; Wu, Zili; Savara, Aditya Ashi

    2014-07-14

    An aromatic alpha-aryl ether compound (a benzyl phenyl ether analogue) was covalently grafted to mesoporous silica SBA-15, to create BPEa-SBA-15. The BPEa-SBA-15 was subjected to successive heating cycles up to 600 °C, with in situ monitoring by DRIFTS. It was found that the toluene moiety coordinates to SBA-15 surface silanol hydroxyl groups via an aromatic–hydroxyl interaction. This interaction is evidenced by a red-shift of the aromatic C–H stretches, as well as a red-shift and broadening of the surface hydroxyl O–H stretches, which are features characteristic of a hydrogen bond. These features remain present during heating until ~400 °C whereupon themore » ether linkage of BPEa-SBA-15 is cleaved, accompanied by loss of the toluene moiety.« less

  15. A model study of atmospheric temperatures and the concentrations of ozone, hydroxyl, and some other photochemically active gases during the glacial, the pre-industrial holocene and the present

    NASA Astrophysics Data System (ADS)

    Crutzen, Paul J.; Bruehl, Christoph

    1993-06-01

    Analysis of air trapped in ice cores shows that the atmospheric contents of the greenhouse gases CO2, CH4 and N2O have increased from the glacial to the preindustrial holocene. Further increases have been occurring during the industrial era, which may have contributed to the observed global warming. In addition, CH4 and N2O play large roles in ozone and hydroxyl chemistry. Here we present a model analysis of the changes in atmospheric temperatures and the concentration of O3, OH and related gases between the three epochs. Despite large changes in the atmospheric contents of CO2, CH4 and N2O, total ozone and tropospheric OH hardly changed between the glacial and preindustrial holocene. The global annual atmospheric CH4 sink increased from 90 to 210 Tg between the glacial and preindustrial, and since then to 510 Tg, largely following the changes in atmospheric concentrations. Our results indicate less than half as much CH4 production from tropical wetlands during the ice age than during the holocene.

  16. [Cellulase and xylanase activities of Fusarium Lk:Fr. genus fungi of different trophic groups].

    PubMed

    Kurchenko, I M; Sokolova, O V; Zhdanova, N M; Iarynchyn, A M; Iovenko, O M

    2008-01-01

    A comparative analysis of cellulase and xylanase activities of 26 fungal strains of phytopathogenic, saprophytic and endophytic Fusarium species has been realized using the qualitative reactions. The rare of their linear growth on the media with carboxymethyl cellulose or xylane has been studied. It was shown that the fungi of genus Fusarium belonging to different trophic groups possessed low activities of investigated enzymes as a whole, but in endophytic strains their levels were lower than in phytopathogenic ones. At the same time the distinct strain dependence of cellulase and xylanase activities was fixed in the fungi of different trophic groups. As far as the cellulase and xylanase activities in phytopathogenic isolates varied from complete absence to high levels, and since the activity maximum for each of the investigated strains was observed in different growth terms the conclusion was made that the cellulase and xylanase activities could not be considered as possible markers of the fungal isolate pathogenicity on the strain level.

  17. SERCA overexpression reduces hydroxyl radical injury in murine myocardium.

    PubMed

    Hiranandani, Nitisha; Bupha-Intr, Tepmanas; Janssen, Paul M L

    2006-12-01

    Hydroxyl radicals (*OH) are involved in the pathogenesis of ischemia-reperfusion injury and are observed in clinical situations, including acute heart failure, stroke, and myocardial infarction. Acute transient exposure to *OH causes an intracellular Ca(2+) overload and leads to impaired contractility. We investigated whether upregulation of sarcoplasmic reticulum Ca(2+)-ATPase function (SERCA) can attenuate *OH-induced dysfunction. Small, contracting right ventricular papillary muscles from wild-type (WT) SERCA1a-overexpressing (transgenic, TG) and SERCA2a heterogeneous knockout (HET) mice were directly exposed to *OH. This brief 2-min exposure led to a transient elevation of diastolic force (F(dia)) and depression of developed force (F(dev)). In WT mice, F(dia) increased to 485 +/- 49% and F(dev) decreased to 11 +/- 3%. In sharp contrast, in TG mice F(dia) increased only to 241 +/- 17%, whereas F(dev) decreased only to 51 +/- 5% (P < 0.05 vs. WT). In HET mice, F(dia) rose more than WT (to 597 +/- 20%, P < 0.05), whereas F(dev) was reduced in a similar amount. After approximately 45 min after *OH exposure, a new steady state was reached: F(dev) returned to 37 +/- 6% and 32 +/- 6%, whereas F(dia) came back to 238 +/- 28% and 292 +/- 17% in WT and HET mice, respectively. In contrast, the sustained dysfunction was significantly less in TG mice: F(dia) and F(dev) returned to 144 +/- 20% and 67 +/- 6%, respectively. Before exposure to *OH, there is decrease in phospholamban (PLB) phosphorylation at Ser16 (pPLBSer16) and PLB phosphorylation at Thr17 (pPLBThr17) in TG mice and an increase in pPLBSer16 and pPLBThr17 in HET mice versus WT. After exposure to *OH there is decrease in pPLBSer16 in WT, TG, and HET mice but no significant change in the level of pPLBThr17 in any group. The results indicate that SERCA overexpression can reduce the *OH-induced contractile dysfunction in murine myocardium, whereas a reduced SR Ca(2+)-ATPase activity aggravates this injury. Loss of

  18. Mutualistic Benefits Generate an Unequal Distribution of Risky Activities Among Unrelated Group Members

    NASA Astrophysics Data System (ADS)

    Kukuk, Penelope F.; Ward, Seamus A.; Jozwiak, Amy

    Recent studies provide a new challenge to the adequacy of theories concerning the evolution of cooperation among nonrelatives: some individuals perform high-risk activities while others do not. We examined a communal hymenopteran species, Lasioglossum(Chilalictus)hemichalceum, to determine why group members engaged in demonstrably risky activities (foraging) tolerate the selfish behavior (remaining in the nest) of unrelated nestmates. Experimental removal of adult females indicated that their presence is required for the protection of brood from ant predators. Nonforagers ensure the continued presence of adults in the nest if the risk-taking foragers die, thereby safeguarding the survival of forager offspring. This results in an unequal distribution of risky activities within social groups in which avoidance of risky activities by some group members is ultimately beneficial to risk takers.

  19. Formation of dibenzofuran, dibenzo-p-dioxin and their hydroxylated derivatives from catechol.

    PubMed

    Altarawneh, Mohammednoor; Dlugogorski, Bogdan Z

    2015-01-21

    We present, in this study, mechanistic and kinetic accounts of the formation of dibenzofuran (DF), dibenzo-p-dioxin (DD) and their hydroxylated derivatives (OHs-DF/OHs-DD) from the catechol (CT) molecule, as a model compound for phenolic constituents in biomass. Self-condensation of two CT molecules produces predominantly a DD molecule via open- and closed-shell corridors. Coupling modes involving the o-semiquinone radical and the CT molecule (o-SQ/CT) generate two direct structural blocks for the formation of OHs-DF/OHs-DD structures, ether-type intermediates and di-keto moieties. The calculated reaction rate constants indicate that the fate of ether-type intermediates is to make hydroxylated diphenyl ethers rather than to undergo cyclisation reactions leading to the formation of preDF structures. Unimolecular loss of a H or OH moiety from a pivotal carbon in these hydroxylated diphenyl ethers then produces hydroxylated and non-hydroxylated DD molecules. Formation of OHs-DF initiated by o(C)-o(C) cross-linkages involving o-SQ/o-SQ and o-SQ/CT reactions incurs very similar reaction and activation enthalpies encountered in the formation of chlorinated DFs from chlorophenols.

  20. Hydroxylated ornithine lipids increase stress tolerance in Rhizobium tropici CIAT899

    PubMed Central

    Vences-Guzmán, Miguel Ángel; Guan, Ziqiang; Ormeño-Orrillo, Ernesto; González-Silva, Napoleón; López-Lara, Isabel M.; Martínez-Romero, Esperanza; Geiger, Otto; Sohlenkamp, Christian

    2011-01-01

    Ornithine lipids (OLs) are widespread among gram-negative bacteria. Their basic structure consists of a 3-hydroxy fatty acyl group attached in amide linkage to the α-amino group of ornithine and a second fatty acyl group ester-linked to the 3-hydroxy position of the first fatty acid. OLs can be hydroxylated within the secondary fatty acyl moiety and this modification has been related to increased stress tolerance. Rhizobium tropici, a nodule-forming α-proteobacterium known for its stress tolerance, forms four different OLs. Studies of the function of these OLs have been hampered due to lack of knowledge about their biosynthesis. Here we describe that OL biosynthesis increases under acid stress and that OLs are enriched in the outer membrane. Using a functional expression screen, the OL hydroxylase OlsE was identified, which in combination with the OL hydroxylase OlsC is responsible for the synthesis of modified OLs in R. tropici. Unlike described OL hydroxylations, the OlsE-catalyzed hydroxylation occurs within the ornithine moiety. Mutants deficient in OlsE or OlsC and double mutants deficient in OlsC/OlsE were characterized. R. tropici mutants deficient in OlsC-mediated OL hydroxylation are more susceptible to acid and temperature stress. All three mutants lacking OL hydroxylases are affected during symbiosis. PMID:21205018

  1. Citrulline, a novel compatible solute in drought-tolerant wild watermelon leaves, is an efficient hydroxyl radical scavenger.

    PubMed

    Akashi, K; Miyake, C; Yokota, A

    2001-11-23

    Drought-tolerant wild watermelon accumulates high levels of citrulline in the leaves in response to drought conditions. In this work, the hydroxyl radical-scavenging activity of citrulline was investigated in vitro. The second-order rate constant for the reaction between citrulline and hydroxyl radicals was found to be 3.9x10(9) M(-1) s(-1), demonstrating that citrulline is one of the most efficient scavengers among compatible solutes examined so far. Moreover, citrulline effectively protected DNA and an enzyme from oxidative injuries. Liquid chromatography-mass spectrometry analysis revealed that at least four major products were formed by the reaction between citrulline and hydroxyl radicals. Activities of metabolic enzymes were not inhibited by up to 600 mM citrulline, indicating that citrulline does not interfere with cellular metabolism. We reasoned, from these results, that citrulline contributes to oxidative stress tolerance under drought conditions as a novel hydroxyl radical scavenger. PMID:11728468

  2. Predicted group II intron lineages E and F comprise catalytically active ribozymes.

    PubMed

    Nagy, Vivien; Pirakitikulr, Nathan; Zhou, Katherine Ismei; Chillón, Isabel; Luo, Jerome; Pyle, Anna Marie

    2013-09-01

    Group II introns are self-splicing, retrotransposable ribozymes that contribute to gene expression and evolution in most organisms. The ongoing identification of new group II introns and recent bioinformatic analyses have suggested that there are novel lineages, which include the group IIE and IIF introns. Because the function and biochemical activity of group IIE and IIF introns have never been experimentally tested and because these introns appear to have features that distinguish them from other introns, we set out to determine if they were indeed self-splicing, catalytically active RNA molecules. To this end, we transcribed and studied a set of diverse group IIE and IIF introns, quantitatively characterizing their in vitro self-splicing reactivity, ionic requirements, and reaction products. In addition, we used mutational analysis to determine the relative role of the EBS-IBS 1 and 2 recognition elements during splicing by these introns. We show that group IIE and IIF introns are indeed distinct active intron families, with different reactivities and structures. We show that the group IIE introns self-splice exclusively through the hydrolytic pathway, while group IIF introns can also catalyze transesterifications. Intriguingly, we observe one group IIF intron that forms circular intron. Finally, despite an apparent EBS2-IBS2 duplex in the sequences of these introns, we find that this interaction plays no role during self-splicing in vitro. It is now clear that the group IIE and IIF introns are functional ribozymes, with distinctive properties that may be useful for biotechnological applications, and which may contribute to the biology of host organisms.

  3. Synthesis, spectroscopic characterization and hydroxylation of Mn(II) complexes with bis(2-pyridylmethyl)benzylamine.

    PubMed

    Li, Jun-Feng; Chen, Qiu-Yun

    2009-07-01

    Two new Mn(II) complexes of bis(2-pyridylmethyl)benzylamine (bpa) were synthesized and characterized by elemental analyses, IR and UV-visible spectroscopies, thermal analyses and ES-MS. These complexes are stable in air with the formula of [(pba)2Mn2Cl2(micro-Cl)2] (1) and [(pba)2Mn2(H2O)2(micro-Ac)2] (Ac)2 (2). The spectroscopic titration results show that the complexes could react with H2O2 resulting active oxidants, which could cause the intramolecular aromatic hydroxylation. The hydroxylated ligand (pba-OH) was confirmed by ES-MS and HPLC. PMID:19223230

  4. Regioselective alkane hydroxylation with a mutant CYP153A6 enzyme

    DOEpatents

    Koch, Daniel J.; Arnold, Frances H.

    2013-01-29

    Cytochrome P450 CYP153A6 from Myobacterium sp. strain HXN1500 was engineered using in-vivo directed evolution to hydroxylate small-chain alkanes regioselectively. Mutant CYP153A6-BMO1 selectively hydroxylates butane and pentane at the terminal carbon to form 1-butanol and 1-pentanol, respectively, at rates greater than wild-type CYP153A6 enzymes. This biocatalyst is highly active for small-chain alkane substrates and the regioselectivity is retained in whole-cell biotransformations.

  5. Effect of cardiopulmonary C fibre activation on the firing activity of ventral respiratory group neurones in the rat.

    PubMed Central

    Wilson, C G; Bonham, A C

    1997-01-01

    1. Cardiopulmonary C fibre receptor stimulation elicits apnoea and rapid shallow breathing, but the effects on the firing activity of central respiratory neurones are not well understood. This study examined the responses of ventral respiratory group neurones: decrementing expiratory (Edec), augmenting expiratory (Eaug), and inspiratory (I) neurones during cardiopulmonary C fibre receptor-evoked apnoea and rapid shallow breathing. 2. Extracellular neuronal activity, phrenic nerve activity and arterial pressure were recorded in urethane-anaesthetized rats. Cardiopulmonary C fibre receptors were stimulated by right atrial injections of phenylbiguanide. Neurones were tested for antidromic activation from the contra- and ipsilateral ventral respiratory group (VRG), spinal cord and cervical vagus nerve. 3. Edec neurones discharged tonically during cardiopulmonary C fibre-evoked apnoea and rapid shallow breathing, displaying increased burst durations, number of impulses per burst, and mean impulse frequencies. Edec neurones recovered either with the phrenic nerve activity (25 s) or much later (3 min). 4. By contrast, the firing activity of Eaug and most I neurones was decreased, featuring decreased burst durations and number of impulses per burst and increased interburst intervals. Eaug activity recovered in approximately 3 min and inspiratory activity in approximately 1 min. 5. The results indicate that cardiopulmonary C fibre receptor stimulation causes tonic firing of Edec neurones and decreases in Eaug and I neuronal activity coincident with apnoea or rapid shallow breathing. PMID:9365917

  6. Global tropospheric hydroxyl distribution, budget and reactivity

    NASA Astrophysics Data System (ADS)

    Lelieveld, Jos; Gromov, Sergey; Pozzer, Andrea; Taraborrelli, Domenico

    2016-10-01

    The self-cleaning or oxidation capacity of the atmosphere is principally controlled by hydroxyl (OH) radicals in the troposphere. Hydroxyl has primary (P) and secondary (S) sources, the former mainly through the photodissociation of ozone, the latter through OH recycling in radical reaction chains. We used the recent Mainz Organics Mechanism (MOM) to advance volatile organic carbon (VOC) chemistry in the general circulation model EMAC (ECHAM/MESSy Atmospheric Chemistry) and show that S is larger than previously assumed. By including emissions of a large number of primary VOC, and accounting for their complete breakdown and intermediate products, MOM is mass-conserving and calculates substantially higher OH reactivity from VOC oxidation compared to predecessor models. Whereas previously P and S were found to be of similar magnitude, the present work indicates that S may be twice as large, mostly due to OH recycling in the free troposphere. Further, we find that nighttime OH formation may be significant in the polluted subtropical boundary layer in summer. With a mean OH recycling probability of about 67 %, global OH is buffered and not sensitive to perturbations by natural or anthropogenic emission changes. Complementary primary and secondary OH formation mechanisms in pristine and polluted environments in the continental and marine troposphere, connected through long-range transport of O3, can maintain stable global OH levels.

  7. Physical Activity and Depressive Symptoms in Four Ethnic Groups of Midlife Women

    PubMed Central

    Im, Eun-Ok; Ham, Ok Kyung; Chee, Eunice; Chee, Wonshik

    2014-01-01

    The purpose of this study was to determine the associations between physical activity and depression and the multiple contextual factors influencing these associations in four major ethnic-groups of midlife women in the U.S. This was a secondary analysis of the data from 542 midlife women. The instruments included questions on background characteristics and health and menopausal status; the Depression Index for Midlife Women; and the Kaiser Physical Activity Survey. The data were analyzed using chi-square tests, the ANOVA, twoway ANOVA, correlation analyses, and hierarchical multiple regression analyses. The women's depressive symptoms were negatively correlated with active living and sports/exercise physical activities whereas they were positively correlated with occupational physical activities (p < .01). Family income was the strongest predictor of their depressive symptoms. Increasing physical activity may improve midlife women's depressive symptoms, but the types of physical activity and multiple contextual factors need to be considered in intervention development. PMID:24879749

  8. Net proton-hydroxyl permeability of large unilamellar liposomes measured by an acid-base titration technique.

    PubMed

    Nichols, J W; Deamer, D W

    1980-04-01

    The net proton-hydroxyl permeability of large unilamellar liposomes has been measured by an acid-base pulse titration technique and has been determined to be several orders of magnitude greater than that measured for other monovalent ions. This permeability is relatively insensitive to variations in lipid composition. Proton permeability and hydroxyl permeability vary with pH 6 to 8, and this variation can occur in the absence of alterations in surface charge density resulting from titrations of acidic and basic groups on the lipids. In order to account for the exceptionally high proton-hydroxyl permeability with respect to other monovalent ions, we propose that protons or hydroxyls or both interact with clusters of hydrogen-bonded water molecules in the lipid bilayer, such that they are transferred across the bilayer by rearrangement of hydrogen bonds in a manner similar to their transport in water and ice.

  9. Salivary alpha amylase activity in human beings of different age groups subjected to psychological stress.

    PubMed

    Sahu, Gopal K; Upadhyay, Seema; Panna, Shradha M

    2014-10-01

    Salivary alpha-amylase (sAA) has been proposed as a sensitive non-invasive biomarker for stress-induced changes in the body that reflect the activity of the sympathetic nervous system. Though several experiments have been conducted to determine the validity of this salivary component as a reliable stress marker in human subjects, the effect of stress induced changes on sAA level in different age groups is least studied. This article reports the activity of sAA in human subjects of different age groups subjected to psychological stress induced through stressful video clip. Differences in sAA level based on sex of different age groups under stress have also been studied. A total of 112 subjects consisting of both the male and female subjects, divided into two groups on basis of age were viewed a video clip of corneal transplant surgery as stressor. Activity of sAA from saliva samples of the stressed subjects were measured and compared with the activity of the samples collected from the subjects before viewing the clip. The age ranges of subjects were 18-25 and 40-60 years. The sAA level increased significantly in both the groups after viewing the stressful video. The increase was more pronounced in the younger subjects. The level of sAA was comparatively more in males than females in the respective groups. No significant change in sAA activity was observed after viewing the soothed video clip. Significant increase of sAA level in response to psychological stress suggests that it might act as a reliable sympathetic activity biochemical marker in different stages of human beings.

  10. Efficient Biomimetic Hydroxylation Catalysis with a Bis(pyrazolyl)imidazolylmethane Copper Peroxide Complex.

    PubMed

    Wilfer, Claudia; Liebhäuser, Patricia; Hoffmann, Alexander; Erdmann, Hannes; Grossmann, Oleg; Runtsch, Leander; Paffenholz, Eva; Schepper, Rahel; Dick, Regina; Bauer, Matthias; Dürr, Maximilian; Ivanović-Burmazović, Ivana; Herres-Pawlis, Sonja

    2015-12-01

    Bis(pyrazolyl)methane ligands are excellent components of model complexes used to investigate the activity of the enzyme tyrosinase. Combining the N donors 3-tert-butylpyrazole and 1-methylimidazole results in a ligand that is capable of stabilising a (μ-η(2) :η(2) )-dicopper(II) core that resembles the active centre of tyrosinase. UV/Vis spectroscopy shows blueshifted UV bands in comparison to other known peroxo complexes, due to donor competition from different ligand substituents. This effect was investigated with the help of theoretical calculations, including DFT and natural transition orbital analysis. The peroxo complex acts as a catalyst capable of hydroxylating a variety of phenols by using oxygen. Catalytic conversion with the non-biological phenolic substrate 8-hydroxyquinoline resulted in remarkable turnover numbers. In stoichiometric reactions, substrate-binding kinetics was observed and the intrinsic hydroxylation constant, kox , was determined for five phenolates. It was found to be the fastest hydroxylation model system determined so far, reaching almost biological activity. Furthermore, Hammett analysis proved the electrophilic character of the reaction. This sheds light on the subtle role of donor strength and its influence on hydroxylation activity. PMID:26458073

  11. Short latency activation of pyramidal tract cells by Group I afferent volleys in the cat

    PubMed Central

    Swett, John E.; Bourassa, Charles M.

    1967-01-01

    1. The contralateral bulbar pyramids were explored with low impedance micro-electrodes in cats anaesthetized with chloralose to reveal the effect of Group I afferent volleys (deep radial nerve of the forelimb) on pyramidal tract (Pt) cells. 2. Low rate (0·5/sec) stimulation of Group I afferents produced small responses (5-30 μV) in the bulbar pyramid which could be detected only with response averaging methods. The responses appeared with an initial latency of 7·0-11·2 msec and reached peak amplitude in 15·7 msec (mean latency). The pyramidal tract origin of the potential was demonstrated by its depression at stimulus rates above 1-2 sec and its disappearance at rates above 4/sec. 3. Recordings of neurones in the Group I cortical projection zone of the posterior sigmoid gyrus revealed that several types of cells, including Pt cells, were activated by Group I afferent volleys. 4. Pt cells responding to Group I afferent volleys frequently received convergent actions from low threshold cutaneous nerve volleys. 5. Averaged response recordings from electrodes positioned in the medial portions of the lateral funiculus of the spinal cord at the level of C2, revealed a response to Group I afferent volleys as early as 7·4 msec which possessed the same characteristics as the relayed response to Group I in the bulbar pyramids. Some Pt cells, activated by Group I volleys orthodromically, could also be antidromically activated by stimulation of the recording site in C2. 6. It was concluded that group I afferent volleys can influence, after short latencies, Pt and non-Pt cells and that some of these Pt cells gave rise to axons incorporated in the corticospinal tract. PMID:16992239

  12. Effects of iron on Vitamin C/copper-induced hydroxyl radical generation in bicarbonate-rich water.

    PubMed

    Jansson, Patric J; Del Castillo, Urko; Lindqvist, Christer; Nordström, Tommy

    2005-05-01

    The aim of this study was to evaluate whether iron, like copper, could support Vitamin C mediated hydroxyl radical formation in bicarbonate-rich water. By using the hydroxyl radical indicator coumarin-3-carboxylic acid, we found that iron, in contrast to copper, was not capable to support Vitamin C induced hydroxyl radical formation. However, when 0.2 mg/l iron and 0.1 mg/l copper were both added to bicarbonate supplemented Milli-Q water, the Vitamin C induced formation of 7-hydroxycoumarin, as measured by HPLC analysis, was inhibited by 47.5%. The inhibition of hydroxyl radical formation by iron was also evident in the experiments performed on copper contaminated bicarbonate-rich household drinking water samples. In the presence of 0.2 mg/l of ferric iron the ascorbic acid induced hydroxyl radical formation was inhibited by 36.0-44.6%. This inhibition was even more significant, 47.0-59.2%, when 0.8 mg/l of ferric iron was present. None of the other redox-active metals, e.g. manganese, nickel or cobalt, could support ascorbic acid induced hydroxyl radical formation and did not have any impact on the ascorbic acid/copper-induced hydroxyl radical generation. Our results show, that iron cannot by itself produce hydroxyl radicals in bicarbonate rich water but can significantly reduce Vitamin C/copper-induced hydroxyl radical formation. These findings might partly explain the mechanism for the iron-induced protective effect on various copper related degenerative disorders that earlier has been observed in animal model systems. PMID:16036332

  13. Using activity-based costing to track resource use in group practices.

    PubMed

    Zeller, T L; Siegel, G; Kaciuba, G; Lau, A H

    1999-09-01

    Research shows that understanding how resources are consumed can help group practices control costs. An American Academy of Orthopaedic Surgeons study used an activity-based costing (ABC) system to measure how resources are consumed in providing medical services. Teams of accounting professors observed 18 diverse orthopedic surgery practices. The researchers identified 17 resource-consuming business processes performed by nonphysician office staff. They measured resource consumption by assigning costs to each process according to how much time is spent on related work activities. When group practices understand how their resources are being consumed, they can reduce costs and optimize revenues by making adjustments in how administrative and clinical staff work. PMID:11066706

  14. Magnetic Tilts and Polarity Separations in Sunspot Groups and Active Regions the Cycle 23

    NASA Astrophysics Data System (ADS)

    Zharkov, S. I.; Zharkova, V. V.

    2006-08-01

    We present the analysis of magnetic tilts in active regions and sunspot groups for 1996-2005 that are automatically extracted from the Solar Feature Catalogues (http://solar.inf.brad.ac.uk ). We investigate the statistical variations of magnetic field tilt in sunspot groups and whole active regions, their longitudinal and latitudinal distributions, drifts and daily polarity separation during different phases of the solar cycle 23. The classification results are compared with the similar research for the previous cycles and the specifics on the cycle 23 is discussed in conjunction to the solar dynamo theory.

  15. Using activity-based costing to track resource use in group practices.

    PubMed

    Zeller, T L; Siegel, G; Kaciuba, G; Lau, A H

    1999-09-01

    Research shows that understanding how resources are consumed can help group practices control costs. An American Academy of Orthopaedic Surgeons study used an activity-based costing (ABC) system to measure how resources are consumed in providing medical services. Teams of accounting professors observed 18 diverse orthopedic surgery practices. The researchers identified 17 resource-consuming business processes performed by nonphysician office staff. They measured resource consumption by assigning costs to each process according to how much time is spent on related work activities. When group practices understand how their resources are being consumed, they can reduce costs and optimize revenues by making adjustments in how administrative and clinical staff work.

  16. Circadian activity rhythm in pre-pubertal and pubertal marmosets (Callithrix jacchus) living in family groups.

    PubMed

    Melo, Paula R; Gonçalves, Bruno S B; Menezes, Alexandre A L; Azevedo, Carolina V M

    2016-03-01

    In marmosets, a phase advance was observed in activity onset in pubertal animals living in captivity under semi-natural conditions which had stronger correlation with the times of sunrise over the course of the year than the age of the animal. In order to evaluate the effect of puberty on the circadian activity rhythm in male and female marmosets living in family groups in controlled lighting conditions, the activity of 5 dyads of twins (4 ♀/♂ and 1 ♂/♂) and their respective parents was continuously monitored by actiwatches between the 4th and 12th months of age. The families were kept under LD 12:12 h with constant humidity and temperature. The onset of puberty was identified by monitoring fecal steroids. Juveniles showed higher totals of daily activity and differences in the daily distribution of activity in relation to parents, in which the bimodal profile was characterized by higher levels in evening activity in relation to morning activity. Regarding the phase, the activity onset and offset, occurred later in relation to parents. After entering puberty, the activity onset and offset occurred later and there was an increase in total daily activity. On the other hand, when assessing the effect of sex, only females showed a delay in the activity offset and an increase in total daily activity. Therefore, the circadian activity rhythm in marmosets has peculiar characteristics in the juvenile stage in relation to the total of daily activity, the onset and offset of the active phase, and the distribution of activity during this phase. Besides, the entering puberty was associated with a phase delay and increase on total daily activity, with differences between sexes, possibly due to hormonal influences and/or social modulation on rhythm. PMID:26724713

  17. Circadian activity rhythm in pre-pubertal and pubertal marmosets (Callithrix jacchus) living in family groups.

    PubMed

    Melo, Paula R; Gonçalves, Bruno S B; Menezes, Alexandre A L; Azevedo, Carolina V M

    2016-03-01

    In marmosets, a phase advance was observed in activity onset in pubertal animals living in captivity under semi-natural conditions which had stronger correlation with the times of sunrise over the course of the year than the age of the animal. In order to evaluate the effect of puberty on the circadian activity rhythm in male and female marmosets living in family groups in controlled lighting conditions, the activity of 5 dyads of twins (4 ♀/♂ and 1 ♂/♂) and their respective parents was continuously monitored by actiwatches between the 4th and 12th months of age. The families were kept under LD 12:12 h with constant humidity and temperature. The onset of puberty was identified by monitoring fecal steroids. Juveniles showed higher totals of daily activity and differences in the daily distribution of activity in relation to parents, in which the bimodal profile was characterized by higher levels in evening activity in relation to morning activity. Regarding the phase, the activity onset and offset, occurred later in relation to parents. After entering puberty, the activity onset and offset occurred later and there was an increase in total daily activity. On the other hand, when assessing the effect of sex, only females showed a delay in the activity offset and an increase in total daily activity. Therefore, the circadian activity rhythm in marmosets has peculiar characteristics in the juvenile stage in relation to the total of daily activity, the onset and offset of the active phase, and the distribution of activity during this phase. Besides, the entering puberty was associated with a phase delay and increase on total daily activity, with differences between sexes, possibly due to hormonal influences and/or social modulation on rhythm.

  18. Barriers for recess physical activity: a gender specific qualitative focus group exploration

    PubMed Central

    2014-01-01

    Background Many children, in particular girls, do not reach the recommended amount of daily physical activity. School recess provides an opportunity for both boys and girls to be physically active, but barriers to recess physical activity are not well understood. This study explores gender differences in children’s perceptions of barriers to recess physical activity. Based on the socio-ecological model four types of environmental barriers were distinguished: natural, social, physical and organizational environment. Methods Data were collected through 17 focus groups (at 17 different schools) with in total 111 children (53 boys) from fourth grade, with a mean age of 10.4 years. The focus groups included an open group discussion, go-along group interviews, and a gender segregated post-it note activity. A content analysis of the post-it notes was used to rank the children’s perceived barriers. This was verified by a thematic analysis of transcripts from the open discussions and go-along interviews. Results The most frequently identified barriers for both boys and girls were weather, conflicts, lack of space, lack of play facilities and a newly-found barrier, use of electronic devices. While boys and girls identified the same barriers, there were both inter- and intra-gender differences in the perception of these barriers. Weather was a barrier for all children, apart from the most active boys. Conflicts were perceived as a barrier particularly by those boys who played ballgames. Girls said they would like to have more secluded areas added to the school playground, even in large schoolyards where lack of space was not a barrier. This aligned with girls’ requests for more “hanging-out” facilities, whereas boys primarily wanted activity promoting facilities. Conclusion Based on the results from this study, we recommend promoting recess physical activity through a combination of actions, addressing barriers within the natural, social, physical and

  19. Involving postgraduate's students in undergraduate small group teaching promotes active learning in both

    PubMed Central

    Kalra, Ruchi; Modi, Jyoti Nath; Vyas, Rashmi

    2015-01-01

    Background: Lecture is a common traditional method for teaching, but it may not stimulate higher order thinking and students may also be hesitant to express and interact. The postgraduate (PG) students are less involved with undergraduate (UG) teaching. Team based small group active learning method can contribute to better learning experience. Aim: To-promote active learning skills among the UG students using small group teaching methods involving PG students as facilitators to impart hands-on supervised training in teaching and managerial skills. Methodology: After Institutional approval under faculty supervision 92 UGs and 8 PGs participated in 6 small group sessions utilizing the jigsaw technique. Feedback was collected from both. Observations: Undergraduate Feedback (Percentage of Students Agreed): Learning in small groups was a good experience as it helped in better understanding of the subject (72%), students explored multiple reading resources (79%), they were actively involved in self-learning (88%), students reported initial apprehension of performance (71%), identified their learning gaps (86%), team enhanced their learning process (71%), informal learning in place of lecture was a welcome change (86%), it improved their communication skills (82%), small group learning can be useful for future self-learning (75%). Postgraduate Feedback: Majority performed facilitation for first time, perceived their performance as good (75%), it was helpful in self-learning (100%), felt confident of managing students in small groups (100%), as facilitator they improved their teaching skills, found it more useful and better identified own learning gaps (87.5%). Conclusions: Learning in small groups adopting team based approach involving both UGs and PGs promoted active learning in both and enhanced the teaching skills of the PGs. PMID:26380201

  20. Novel method for the preparation of polymethacrylates with nonlinear optically active side groups

    NASA Astrophysics Data System (ADS)

    Strohriegl, Peter; Mueller, Harry; Nuyken, Oskar

    1993-01-01

    Because of their excellent optical properties, a variety of polymethacrylates with pendant NLO-chromophores has been prepared and investigated by different research groups. The method normally used for the synthesis of these polymers is the free radical polymerization of the corresponding methacrylates with NLO-active side groups. However, the NLO- chromophores, usually large conjugated molecules with an electron donor and an electron acceptor substituent, often contain a number of functional groups, e.g., nitro- or azo groups. These may act as retarders or inhibitors in a free radical polymerization. So in many cases the yields are not quantitative and the molecular weights are quite low. We present an alternative method for the preparation of polymethacrylates with pendant NLO-chromophores, the polymeranalogous esterification of poly(methacryloyl chloride). In a first step, reactive prepolymers are prepared by the free radical polymerization of methacryloyl chloride (MAC1) or by copolymerization of MAC1 with methyl methacrylate (MMA). These prepolymers are esterified using NLO-active side groups with a hydroxy-terminated spacer. Well defined, high molecular weight polymethacrylates with high dye contents can be prepared by this method. A copolymer with 19 mole% of azochromophores exhibits an electro-optical coefficient of 9 pm/V at 1300 mm after poling, whereas 19 pm/V (1500 nm) were measured for a polymer with 90 mole% of NLO active azobenzene side groups. In addition, the novel method provides easy access to some novel copolymers with both NLO-active azobenzene units and photocrosslinkable cinnamoyl groups.

  1. A method to quantify movement activity of groups of animals using automated image analysis

    NASA Astrophysics Data System (ADS)

    Xu, Jianyu; Yu, Haizhen; Liu, Ying

    2009-07-01

    Most physiological and environmental changes are capable of inducing variations in animal behavior. The behavioral parameters have the possibility to be measured continuously in-situ by a non-invasive and non-contact approach, and have the potential to be used in the actual productions to predict stress conditions. Most vertebrates tend to live in groups, herds, flocks, shoals, bands, packs of conspecific individuals. Under culture conditions, the livestock or fish are in groups and interact on each other, so the aggregate behavior of the group should be studied rather than that of individuals. This paper presents a method to calculate the movement speed of a group of animal in a enclosure or a tank denoted by body length speed that correspond to group activity using computer vision technique. Frame sequences captured at special time interval were subtracted in pairs after image segmentation and identification. By labeling components caused by object movement in difference frame, the projected area caused by the movement of every object in the capture interval was calculated; this projected area was divided by the projected area of every object in the later frame to get body length moving distance of each object, and further could obtain the relative body length speed. The average speed of all object can well respond to the activity of the group. The group activity of a tilapia (Oreochromis niloticus) school to high (2.65 mg/L) levels of unionized ammonia (UIA) concentration were quantified based on these methods. High UIA level condition elicited a marked increase in school activity at the first hour (P<0.05) exhibiting an avoidance reaction (trying to flee from high UIA condition), and then decreased gradually.

  2. [Preparation, characterization and adsorption performance of mesoporous activated carbon with acidic groups].

    PubMed

    Li, Kun-Quan; Li, Ye; Zheng, Zheng; Zhang, Yu-Xuan

    2013-06-01

    Mesoporous activated carbons containing acidic groups were prepared with cotton stalk based fiber as raw materials and H3PO4 as activating agent by one step carbonization method. Effects of impregnation ratio, carbonization temperature and heat preservation time on the yield, elemental composition, oxygen-containing acid functional groups and adsorptive capacity of activated carbon were studied. The adsorption capacity of the prepared activated carbon AC-01 for p-nitroaniline and Pb(II) was studied, and the adsorption mechanism was also suggested according to the equilibrium experimental results. The maximum yield of activated carbons prepared from cotton stalk fiber reached 35.5% when the maximum mesoporous volume and BET surface area were 1.39 cm3 x g(-1) and 1 731 m2 x g(-1), respectively. The activated carbon AC-01 prepared under a H3 PO4/precursor ratio of 3:2 and activated at 900 degrees C for 90 min had a total pore volume of 1.02 cm3 x g(-1), a micoporous ratio of 31%, and a mesoporous ratio of 65%. The pore diameter of the mesoporous activated carbon was mainly distributed in the range of 2-5 nm. The Langmuir maximum adsorption capacities of Pb(II) and p-nitroaniline on cotton stalk fiber activated carbon were 123 mg x g(-1) and 427 mg x g(-1), respectively, which were both higher than those for commercial activated carbon fiber ACF-CK. The equilibrium adsorption experimental data showed that mesopore and oxygen-containing acid functional groups played an important role in the adsorption. PMID:23947073

  3. Menopausal symptoms and physical activity in multiethnic groups of midlife women: A secondary analysis

    PubMed Central

    Chang, Sun Ju; Chee, Wonshik; Im, Eun-Ok

    2013-01-01

    Aims To explore the effect of diverse types of women’s physical activity on menopausal symptoms among multiethnic groups of midlife women in the USA. Background Although physical activity is one of the most widely used non-pharmacological methods for managing menopausal symptoms, there is a paucity of clinical guidelines for women and healthcare providers because the relationship between physical activity and menopausal symptoms has been found inconsistent in previous studies. Design A secondary analysis of the data from a lager Internet survey study conducted in 2008 – 2010. Methods A total of 481 midlife women among four ethnic groups were selected from the original study. The data were collected using the Kaiser Physical Activity Survey and the Midlife Women’s Symptom Index. Bivariate correlation analyses and hierarchical multiple regression analyses were used to analyze the data. Results/Findings The household/caregiving activity index was positively associated with the prevalence scores of the psychological symptoms in both Non-Hispanic Asians and Non-Hispanic African Americans. The increased sports/exercise activity index was negatively associated with the severity scores of the physical symptoms in both Hispanics and Non-Hispanic Whites. The occupational activity index and the active living activity index significantly predicted the severity scores of the psychosomatic symptoms in Hispanics and Non-Hispanic African Americans, respectively. Conclusion Nurses who take care of multiethnic groups of midlife women who experience menopausal symptoms should be aware of diverse types of women’s physical activities within the cultural context. PMID:23171423

  4. Hydroxyl radical production and oxidative damage induced by cadmium and naphthalene in liver of Carassius auratus.

    PubMed

    Shi, Huahong; Sui, Yunxia; Wang, Xiaorong; Luo, Yi; Ji, Liangliang

    2005-01-01

    Freshwater goldfish (Carassius auratus) were exposed to cadmium (Cd) from 0 to 5 mg/L, and naphthalene (NAP) from 0 to 50 mg/L. Twenty-four hours after the exposure, reactive oxygen species (ROS) was trapped by phenyl-tert-butyl nitrone and detected by electron paramagnetic resonance (EPR). Protein carbonyl (PCO) and lipid peroxidation (LPO) content were determined. The activities of superoxide dismutase (SOD) and catalase (CAT) were also measured. The EPR spectra signals were characterized by prominent six-line spectra, which were defined as hydroxyl radical ((.)OH). As compared to the control group, Cd and NAP significantly induced (.)OH production marked by the intensity of the prominent spectra at higher concentrations. Both xenobiotics also increased LPO content and PCO content, depending on the concentrations. Either LPO or PCO content showed significant relation with (.)OH production. Cd increased the activity of SOD and decreased that of CAT at 5 mg/L, and NAP increased the activities of SOD and CAT at 5 mg/L. The results clearly indicated that these two structurally different non-redox cycling xenobiotics could induce (.)OH generation and result in oxidative damage in liver of C. auratus, and these effects were concentration-dependent.

  5. Poly(hydroxyl urethane) compositions and methods of making and using the same

    DOEpatents

    Luebke, David; Nulwala, Hunaid; Tang, Chau

    2016-01-26

    Methods and compositions relating to poly(hydroxyl urethane) compounds are described herein that are useful as, among other things, binders and adhesives. The cross-linked composition is achieved through the reaction of a cyclic carbonate, a compound having two or more thiol groups, and a compound having two or more amine functional groups. In addition, a method of adhesively binding two or more substrates using the cross-linked composition is provided.

  6. Poly(hydroxyl urethane) compositions and methods of making and using the same

    DOEpatents

    Luebke, David; Nulwala, Hunaid; Tang, Chau

    2014-12-16

    Methods and compositions relating to poly(hydroxyl urethane) compounds are described herein that are useful as, among other things, binders and adhesives. The cross-linked composition is achieved through the reaction of a cyclic carbonate, a compound having two or more thiol groups, and a compound having two or more amine functional groups. In addition, a method of adhesively binding two or more substrates using the cross-linked composition is provided.

  7. Effects of hydroxylation and silanization on the surface properties of ZnO nanowires.

    PubMed

    García Núñez, C; Sachsenhauser, M; Blashcke, B; García Marín, A; Garrido, Jose A; Pau, Jose L

    2015-03-11

    Silanization is commonly used to form bonds between inorganic materials and biomolecules as a step in the surface preparation of solid-state biosensors. This work investigates the effects of silanization with amino-propyldiethoxymethylsilane on hydroxylated sidewalls of zinc oxide (ZnO) nanowires (NWs). The surface properties and electrical characteristics of NWs are analyzed by different techniques after their hydroxylation and later silanization. Contact angle measurements reveal a stronger hydrophobic behavior after silanization, and X-ray photoelectron spectroscopy (XPS) results show a reduction of the surface dipole induced by the replacement of the hydroxyl group with the amine terminal group. The lower work function obtained after silanization in contact potential measurements corroborates the attenuation of the surface dipole observed in XPS. Furthermore, the surface band bending of NWs is determined from surface photovoltage measurements upon irradiation with UV light, yielding a 0.5 eV energy in hydroxylated NWs, and 0.18 eV, after silanization. From those results, a reduction in the surface state density of 3.1 × 10(11) cm(-2) is estimated after silanization. The current-voltage (I-V) characteristics measured in a silanized single NW device show a reduction of the resistance, due to the enhancement of the conductive volume inside the NW, which also improves the linearity of the I-V characteristic.

  8. Hydroxyl-radical-induced degradative oxidation of beta-lactam antibiotics in water: absolute rate constant measurements.

    PubMed

    Dail, Michelle K; Mezyk, Stephen P

    2010-08-19

    The beta-lactam antibiotics are some of the most prevalent pharmaceutical contaminants currently being detected in aquatic environments. Because the presence of any trace level of antibiotic in water may adversely affect aquatic ecosystems and contribute to the production of antibiotic-resistant bacteria, active removal by additional water treatments, such as using advanced oxidation and reduction processes (AO/RPs), may be required. However, to ensure that any AOP treatment process occurs efficiently and quantitatively, a full understanding of the kinetics and mechanisms of all of the chemical reactions involved under the conditions of use is necessary. In this study, we report on our kinetic measurements for the hydroxyl-radical-induced oxidation of 11 beta-lactam antibiotics obtained using electron pulse radiolysis techniques. For the 5-member ring species, an average reaction rate constant of (7.9 +/- 0.8) x 10(9) M(-1) s(-1) was obtained, slightly faster than for the analogous 6-member ring containing antibiotics, (6.6 +/- 1.2) x 10(9) M(-1) s(-1). The consistency of these rate constants for each group infers a common reaction mechanism, consisting of the partitioning of the hydroxyl radical between addition to peripheral aromatic rings and reaction with the central double-ring core of these antibiotics.

  9. Origin of Coverage Dependence in Photoreactivity of Carboxylate on TiO2(110): Hindering by Charged Coadsorbed Hydroxyls

    SciTech Connect

    Wang, Zhitao; Henderson, Michael A.; Lyubinetsky, Igor

    2015-09-30

    The influence of reactant coverage on photochemical activity was explored using scanning tunneling microscopy (STM) and ultraviolet photoelectron spectroscopy (UPS). We observed diminished reactivity of carboxylate species (trimethyl acetate, TMA) on TiO2(110) as a function of increasing coverage. This effect was not linked to intermolecular interactions of TMA but to the accumulation of the coadsorbed bridging hydroxyls (HOb) deposited during (thermal) dissociative adsorption of the parent, trimethylacetic acid (TMAA). Confirmation of the hindering influence of HOb groups was obtained by the observation that HOb species originated from H2O dissociation at O-vacancy sites have a similar hindering effect on TMA photochemistry. Though HOb’s are photoinactive on TiO2(110) under ultrahigh vacuum conditions, UPS results show that these sites trap photoexcited electrons, which in turn likely (electrostatically) attract and neutralize photoexcited holes, thus suppressing the hole-mediated photoreactivity of TMA. This negative influence of surface hydroxyls on hole-mediated photochemistry is likely a major factor in other anaerobic photochemical processes on reducible oxide surfaces.

  10. Solvent-free lipase-catalyzed synthesis of a novel hydroxyl-fatty acid derivative of kojic acid.

    PubMed

    El-Boulifi, Noureddin; Ashari, Siti Efliza; Serrano, Marta; Aracil, Jose; Martínez, Mercedes

    2014-02-01

    The aim of this work was the synthesis of a novel hydroxyl-fatty acid derivative of kojic acid rich in kojic acid monoricinoleate (KMR) which can be widely used in the cosmetic and food industry. The synthesis of KMR was carried out by lipase-catalysed esterification of ricinoleic and kojic acids in solvent-free system. Three immobilized lipases were tested and the best KMR yields were attained with Lipozyme TL IM and Novozym 435. Since Lipozyme TL IM is the cheapest, it was selected to optimize the reaction conditions. The optimal reaction conditions were 80 °C for the temperature, 1:1 for the alcohol/acid molar ratio, 600 rpm for stirring speed and 7.8% for the catalyst concentration. Under these conditions, the reaction was scaled up in a 5×10⁻³ m³ stirred tank reactor. ¹H-¹³C HMBC-NMR showed that the primary hydroxyl group of kojic acid was regioselectively esterified. The KMR has more lipophilicity than kojic acid and showed antioxidant activity that improves the oxidation stability of biodiesel.

  11. Finding synergies in fuels properties for the design of renewable fuels--hydroxylated biodiesel effects on butanol-diesel blends.

    PubMed

    Sukjit, E; Herreros, J M; Piaszyk, J; Dearn, K D; Tsolakis, A

    2013-04-01

    This article describes the effects of hydroxylated biodiesel (castor oil methyl ester - COME) on the properties, combustion, and emissions of butanol-diesel blends used within compression ignition engines. The study was conducted to investigate the influence of COME as a means of increasing the butanol concentration in a stable butanol-diesel blend. Tests were compared with baseline experiments using rapeseed methyl esters (RME). A clear benefit in terms of the trade-off between NOX and soot emissions with respect to ULSD and biodiesel-diesel blends with the same oxygen content was obtained from the combination of biodiesel and butanol, while there was no penalty in regulated gaseous carbonaceous emissions. From the comparison between the biodiesel fuels used in this work, COME improved some of the properties (for example lubricity, density and viscosity) of butanol-diesel blends with respect to RME. The existence of hydroxyl group in COME also reduced further soot emissions and decreased soot activation energy. PMID:23452309

  12. Enhancement of lactase activity in milk by reactive sulfhydryl groups induced by heat treatment.

    PubMed

    Jiménez-Guzmán, J; Cruz-Guerrero, A E; Rodríguez-Serrano, G; López-Munguía, A; Gómez-Ruiz, L; García-Garibay, M

    2002-10-01

    The effects of heat treatments of milk and whey prior to lactose hydrolysis with Kluyveromyces lactis beta-galactosidase were studied. It was observed that heat treatment of milk significantly increases lactase activity, with a maximum activity increase found when milk was heated at 55 degrees C. In whey from 55 up to 75 degrees C, beta-galactosidase activity decreased slightly. Nevertheless, heating whey at 85 degrees C for 30 min raised the rate of hydrolysis significantly. Electrophoretic patterns and UV spectra proved that the activity change correlated with milk protein denaturation, particularly that of beta-lactoglobulin. Heating whey permeate did not increase the enzyme activity as heating whole whey; but heating whey prior to ultrafiltration also resulted in enzyme activation. Measurement of free sulfhydryl (SH) groups in both whey and heated whey permeate showed that the liberation of free SH is highly correlated to the change of the activity. Furthermore, this activation can be reversed by oxidizing the reactive sulfhydryl groups, proving that the observed effect may be related to the release of free SH to the medium, rather than to the denaturation of a thermolabile protein inhibitor.

  13. Physical activity and beverage consumption in preschoolers: focus groups with parents and teachers

    PubMed Central

    2013-01-01

    Background Qualitative research is a method in which new ideas and strategies can be discovered. This qualitative study aimed to investigate parents’ and teachers’ opinions on physical activity and beverage consumption of preschool children. Through separate, independent focus groups, they expressed their perceptions on children’s current physical activity and beverage consumption levels, factors that influence and enhance these behaviours, and anticipated barriers to making changes. Methods Multi-cultural and multi-geographical focus groups were carried out in six European countries (Belgium, Bulgaria, Germany, Greece, Poland and Spain). In total, twenty-four focus groups with 122 parents and eighteen focus groups with 87 teachers were conducted between October 2010 and January 2011. Based on a semi-structured interview guide, questions on preschoolers’ physical activity (opinions on preschoolers’ physical activity, how to increase physical activity, facilitators and barriers of physical activity) and beverage consumption (rules and policies, factors influencing promotion of healthy drinking, recommendations for future intervention development) were asked. The information was analyzed using qualitative data analysis software (NVivo8). Results The focus group results indicated misperceptions of caregivers on preschoolers’ physical activity and beverage consumption levels. Caregivers perceived preschoolers as sufficiently active; they argue that children need to learn to sit still in preparation for primary school. At most preschools, children can drink only water. In some preschools sugar-sweetened beverages like chocolate milk or fruit juices, are also allowed. It was mentioned that sugar-sweetened beverages can be healthy due to mineral and vitamin content, although according to parents their daily intake is limited. These opinions resulted in low perceived needs to change behaviours. Conclusions Although previous research shows need of change in

  14. Methyl-esterified 3-hydroxybutyrate oligomers protect bacteria from hydroxyl radicals.

    PubMed

    Koskimäki, Janne J; Kajula, Marena; Hokkanen, Juho; Ihantola, Emmi-Leena; Kim, Jong H; Hautajärvi, Heidi; Hankala, Elina; Suokas, Marko; Pohjanen, Johanna; Podolich, Olga; Kozyrovska, Natalia; Turpeinen, Ari; Pääkkönen, Mirva; Mattila, Sampo; Campbell, Bruce C; Pirttilä, Anna Maria

    2016-05-01

    Bacteria rely mainly on enzymes, glutathione and other low-molecular weight thiols to overcome oxidative stress. However, hydroxyl radicals are the most cytotoxic reactive oxygen species, and no known enzymatic system exists for their detoxification. We now show that methyl-esterified dimers and trimers of 3-hydroxybutyrate (ME-3HB), produced by bacteria capable of polyhydroxybutyrate biosynthesis, have 3-fold greater hydroxyl radical-scavenging activity than glutathione and 11-fold higher activity than vitamin C or the monomer 3-hydroxybutyric acid. We found that ME-3HB oligomers protect hypersensitive yeast deletion mutants lacking oxidative stress-response genes from hydroxyl radical stress. Our results show that phaC and phaZ, encoding polymerase and depolymerase, respectively, are activated and polyhydroxybutyrate reserves are degraded for production of ME-3HB oligomers in bacteria infecting plant cells and exposed to hydroxyl radical stress. We found that ME-3HB oligomer production is widespread, especially in bacteria adapted to stressful environments. We discuss how ME-3HB oligomers could provide opportunities for numerous applications in human health. PMID:26974813

  15. Elongation Factor 2 Kinase Is Regulated by Proline Hydroxylation and Protects Cells during Hypoxia

    PubMed Central

    Moore, Claire E. J.; Mikolajek, Halina; Regufe da Mota, Sergio; Wang, Xuemin; Kenney, Justin W.; Werner, Jörn M.

    2015-01-01

    Protein synthesis, especially translation elongation, requires large amounts of energy, which is often generated by oxidative metabolism. Elongation is controlled by phosphorylation of eukaryotic elongation factor 2 (eEF2), which inhibits its activity and is catalyzed by eEF2 kinase (eEF2K), a calcium/calmodulin-dependent α-kinase. Hypoxia causes the activation of eEF2K and induces eEF2 phosphorylation independently of previously known inputs into eEF2K. Here, we show that eEF2K is subject to hydroxylation on proline-98. Proline hydroxylation is catalyzed by proline hydroxylases, oxygen-dependent enzymes which are inactivated during hypoxia. Pharmacological inhibition of proline hydroxylases also stimulates eEF2 phosphorylation. Pro98 lies in a universally conserved linker between the calmodulin-binding and catalytic domains of eEF2K. Its hydroxylation partially impairs the binding of calmodulin to eEF2K and markedly limits the calmodulin-stimulated activity of eEF2K. Neuronal cells depend on oxygen, and eEF2K helps to protect them from hypoxia. eEF2K is the first example of a protein directly involved in a major energy-consuming process to be regulated by proline hydroxylation. Since eEF2K is cytoprotective during hypoxia and other conditions of nutrient insufficiency, it may be a valuable target for therapy of poorly vascularized solid tumors. PMID:25755286

  16. Effects of Active Versus Passive Group Music Therapy on Preadolescents with Emotional, Learning, and Behavioral Disorders.

    PubMed

    Montello; Coons

    1999-01-01

    This study attempted to compare the behavioral effects of active, rhythm-based group music therapy vs. those of passive, listening-based group music therapy on preadolescents with emotional, learning, and behavioral disorders. It was hypothesized that preadolescents who participated in active music therapy would more significantly improve target behaviors than those involved in passive music therapy. Achenbach's Teacher Report Form (TRF) was used to confirm changes among subjects in attention, motivation, and hostility as rated by homeroom teachers. Twelve music therapy sessions were conducted over a 4-month period with three different groups of subjects (n = 16), with two groups participating in active music therapy and the other receiving passive music therapy. Results indicate that subjects improved significantly after receiving both music therapy interventions. The most significant change in subjects was found on the aggression/hostility scale. These results suggest that group music therapy can facilitate the process of serf-expression in emotionally disturbed/learning disabled adolescents and provide a channel for transforming frustration, anger, and aggression into the experience of creativity and self-mastery. Discussion of results also includes recommendations for chousing one music therapy approach over another based on personality types and/or clinical diagnoses of subjects.

  17. Lactate dehydrogenase activity in Bacteroides fragilis group strains with induced resistance to metronidazole.

    PubMed

    Presečki Stanko, Aleksandra; Sóki, Jozsef; Varda Brkić, Dijana; Plečko, Vanda

    2016-06-01

    The aims of this study were to induce in vitro metronidazole resistance in nim-negative Bacteroides fragilis group strains and to determine the lactate dehydrogenase (LDH) activity of the induced strains. A collection of B. fragilis group strains were identified by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF/MS). Minimum inhibitory concentrations (MICs) for metronidazole were determined by the agar dilution technique. The presence of nim genes was screened by PCR. A sample of 52 nim-negative metronidazole-susceptible strains were selected at random and were exposed to metronidazole in the resistance induction experiment. LDH activity was measured by spectrophotometry. Of the 52 selected strains, 12 (23.1%) acquired resistance to metronidazole. MICs ranged from 8mg/L to 96mg/L. Eight of the twelve induced strains displayed decreased LDH activity, whilst only one expressed a significant increase in LDH activity with LDH values of 49.1U/mg and 222.0U/mg, respectively. In conclusion, in vitro induction of metronidazole resistance could be selected in nim-negative B. fragilis group strains. A statistically significant decrease in LDH activity was in contrast to previous findings in which, underlying higher metronidazole MICs, an increase in LDH activity compensated for the decreased activity of pyruvate-ferredoxin oxidoreductase (PFOR). These findings could be explained if the induction caused only physiological and not genetic changes. We believe that genetic mutations in the B. fragilis strain that demonstrated an emergent increase in LDH activity were responsible for the increased activity. PMID:27436459

  18. Climate Impacts on Tropospheric Ozone and Hydroxyl

    NASA Technical Reports Server (NTRS)

    Shindell, Drew T.; Bell, N.; Faluvegi, G.

    2003-01-01

    Climate change may influence tropospheric ozone and OH via several main pathways: (1) altering chemistry via temperature and humidity changes, (2) changing ozone and precursor sources via surface emissions, stratosphere-troposphere exchange, and light- ning, and (3) affecting trace gas sinks via the hydrological cycle and dry deposition. We report results from a set of coupled chemistry-climate model simulations designed to systematically study these effects. We compare the various effects with one another and with past and projected future changes in anthropogenic and natural emissions of ozone precursors. We find that white the overall impact of climate on ozone is probably small compared to emission changes, some significant seasonal and regional effects are apparent. The global effect on hydroxyl is quite large, however, similar in size to the effect of emission changes. Additionally, we show that many of the chemistry-climate links that are not yet adequately modeled are potentially important.

  19. Hydroxyl density measurements with resonant holographic interferometry

    SciTech Connect

    Trolinger, J.D.; Hess, C.F.; Yip, B.; Battles, B.; Hanson, R.K. Stanford University, CA )

    1992-01-01

    This paper describes experimentation with a new type of flow diagnostics referred to as Resonant Holographic Interferometry Spectroscopy (RHIS). This technique combines the power of holography with the species selectivity of spectroscopy to provide three-dimensional images of the density profile of selected species in complex flows. The technique is particularly suitable to study mixing processes as well as to measure minor species in combustion processes. The method would allow the measurement of minor species in the presence of major species, as well as major species in a heterogeneous low pressure environment. Both experiments and modeling are being conducted to establish the feasibility of RHIS in measuring the hydroxyl concentrations in combustion processes. It is expected that in addition to the species concentration, the resonant holographic technique has the potential of providing temperature, pressure, and flow velocity. 28 refs.

  20. Use of a Wiki-Based Software to Manage Research Group Activities

    ERIC Educational Resources Information Center

    Wang, Ting; Vezenov, Dmitri V.; Simboli, Brian

    2014-01-01

    This paper discusses use of the wiki software Confluence to organize research group activities and lab resources. Confluence can serve as an electronic lab notebook (ELN), as well as an information management and collaboration tool. The article provides a case study in how researchers can use wiki software in "home-grown" fashion to…

  1. When Talking Won't Work: Implementing Experiential Group Activities with Addicted Clients

    ERIC Educational Resources Information Center

    Hagedorn, W. Bryce; Hirshhorn, Meredith A.

    2009-01-01

    Traditional talk therapy, particularly cognitive behavioral techniques, are often ineffective when working with addicted clients for many reasons. By tapping into the power of the group modality, experiential activities can serve as a powerful facilitator of insight and behavior change. The authors provide a brief review of the literature followed…

  2. Collaborative Activities Enabled by GroupScribbles (GS): An Exploratory Study of Learning Effectiveness

    ERIC Educational Resources Information Center

    Looi, Chee-Kit; Chen, Wenli; Ng, Foo-Keong

    2010-01-01

    This paper describes the findings of an exploratory cycle of a design-based research project and examines the learning effectiveness of collaborative activities that are supported by the GroupScribbles (GS) software technology in two Singapore primary science classrooms. The students had ten weeks of GS-based lessons in science, which were…

  3. Peer Interactions among Children with Profound Intellectual and Multiple Disabilities during Group Activities

    ERIC Educational Resources Information Center

    Nijs, Sara; Penne, Anneleen; Vlaskamp, Carla; Maes, Bea

    2016-01-01

    Background: Children with profound intellectual and multiple disabilities (PIMD) meet other children with PIMD in day care centres or schools. This study explores the peer-directed behaviours of children with PIMD, the peer interaction-influencing behaviour of the direct support workers and the children's positioning. Method: Group activities for…

  4. Healthful Eating and Physical Activity in the Home Environment: Results from Multifamily Focus Groups

    ERIC Educational Resources Information Center

    Berge, Jerica M.; Arikian, Aimee; Doherty, William J.; Neumark-Sztainer, Dianne

    2012-01-01

    Objective: To explore multiple family members' perceptions of risk and protective factors for healthful eating and physical activity in the home. Design: Ten multifamily focus groups were conducted with 26 families. Setting and Participants: Community setting with primarily black and white families. Family members (n = 103) were aged 8 to 61…

  5. Children's Preferences for Group Musical Activities in Child Care Centres: A Cross-Cultural Study

    ERIC Educational Resources Information Center

    Yim, Hoi Yin Bonnie; Ebbeck, Marjory

    2009-01-01

    This paper reports on a cross-cultural research study of children's preferences for group musical activities in child care centres. A total of 228 young children aged 4-5 years in seven child care centres in Hong Kong and in the Adelaide City of South Australia participated in the study. Both qualitative and quantitative data were collected via a…

  6. An Initial Description and Pilot of Group Behavioral Activation Therapy for Anxious and Depressed Youth

    ERIC Educational Resources Information Center

    Chu, Brian C.; Colognori, Daniela; Weissman, Adam S.; Bannon, Katie

    2009-01-01

    Transdiagnostic approaches for treating multiple problems within a single protocol are novel but gaining support. This report describes initial efforts to adapt reconceptualized behavioral activation (e.g., Jacobson, Martell, & Dimidjian, 2001) to a group format suitable for young adolescents, plus add a powerful exposure component to accommodate…

  7. Osteoporosis Knowledge, Calcium Intake, and Weight-Bearing Physical Activity in Three Age Groups of Women.

    ERIC Educational Resources Information Center

    Terrio, Kate; Auld, Garry W.

    2002-01-01

    Determined the extent and integration of osteoporosis knowledge in three age groups of women, comparing knowledge to calcium intake and weight bearing physical activity (WBPA). Overall calcium intake was relatively high. There were no differences in knowledge, calcium intake, or WBPA by age, nor did knowledge predict calcium intake and WBPA. None…

  8. 75 FR 51525 - Railroad Safety Advisory Committee (RSAC); Working Group Activity Update

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-20

    ... announcement of working group activities and status reports of January 29, 2010 (75 FR 4904). The 41st full... October 11, 2005. The Notice of Proposed Rulemaking (NPRM) was published on August 24, 2006 (71 FR 50275... published on February 1, 2008 (73 FR 6370). The Task Force met on October 17-18, 2007, and reached...

  9. Peer Groups and Substance Use: Examining the Direct and Interactive Effect of Leisure Activity

    ERIC Educational Resources Information Center

    Thorlindsson, Thorolfur; Bernburg, Jon Gunnar

    2006-01-01

    This paper explores the relationships among adolescent leisure activities, peer behavior, and substance use. We suggest that peer group interaction can have a differential effect on adolescent deviant behavior depending on the type of leisure pattern adolescents engage in. We analyze data from a representative national sample of Icelandic…

  10. Information Activities and Appropriation in Teacher Trainees' Digital, Group-Based Learning

    ERIC Educational Resources Information Center

    Hanell, Fredrik

    2016-01-01

    Introduction: This paper reports results from an ethnographic study of teacher trainees' information activities in digital, group-based learning and their relation to the interplay between use and appropriation of digital tools and the learning environment. Method: The participants in the present study are 249 pre-school teacher trainees in…

  11. 77 FR 24257 - Railroad Safety Advisory Committee (RSAC); Working Group Activity Update

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-23

    ... announcement of working group activities and status reports of November 28, 2011 (76 FR 72997). The 45th full... Rulemaking (NPRM) was published on August 24, 2006 (71 FR 50275), and was open for comment until October 23... emergency communication, emergency egress, and rescue access, was published on February 1, 2008 (73 FR...

  12. 77 FR 58608 - Railroad Safety Advisory Committee (RSAC); Working Group Activity Update

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-21

    ... announcement of working group activities and status reports of April 23, 2012 (77 FR 24257). The 46th full RSAC... published on August 24, 2006 (71 FR 50275), and was open for comment until October 23, 2006. The working... communication, emergency egress, and rescue access, was published on February 1, 2008 (73 FR 6370). The...

  13. 75 FR 76070 - Railroad Safety Advisory Committee (RSAC); Working Group Activity Update

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-07

    ... announcement of working group activities and status reports of August 20, 2010 (75 FR 51525). The 42nd full... Rulemaking (NPRM) was published on August 24, 2006 (71 FR 50275), and was open for comment until October 23... emergency communication, emergency egress, and rescue access, was published on February 1, 2008 (73 FR...

  14. Bill Gates' Great-Great-Granddaughter's Honeymoon: An Astronomy Activity for Several Different Age Groups

    ERIC Educational Resources Information Center

    Fraknoi, Andrew

    2009-01-01

    When students finish a unit or course on the planets these days, they are often overwhelmed with facts, comparisons, and images. A good culminating activity, to help them organize their thinking (and review), is to have them divide into small groups (travel agencies) and come up with their top ten solar system "tourist sights" for future space…

  15. Effective L-Tyrosine Hydroxylation by Native and Immobilized Tyrosinase

    PubMed Central

    Lewańczuk, Marcin; Koźlecki, Tomasz; Liesiene, Jolanta; Bryjak, Jolanta

    2016-01-01

    Hydroxylation of L-tyrosine to 3,4-dihydroxyphenylalanine (L-DOPA) by immobilized tyrosinase in the presence of ascorbic acid (AH2), which reduces DOPA-quinone to L-DOPA, is characterized by low reaction yields that are mainly caused by the suicide inactivation of tyrosinase by L-DOPA and AH2. The main aim of this work was to compare processes with native and immobilized tyrosinase to identify the conditions that limit suicide inactivation and produce substrate conversions to L-DOPA of above 50% using HPLC analysis. It was shown that immobilized tyrosinase does not suffer from partitioning and diffusion effects, allowing a direct comparison of the reactions performed with both forms of the enzyme. In typical processes, additional aeration was applied and boron ions to produce the L-DOPA and AH2 complex and hydroxylamine to close the cycle of enzyme active center transformations. It was shown that the commonly used pH 9 buffer increased enzyme stability, with concomitant reduced reactivity of 76%, and that under these conditions, the maximal substrate conversion was approximately 25 (native) to 30% (immobilized enzyme). To increase reaction yield, the pH of the reaction mixture was reduced to 8 and 7, producing L-DOPA yields of approximately 95% (native enzyme) and 70% (immobilized). A three-fold increase in the bound enzyme load achieved 95% conversion in two successive runs, but in the third one, tyrosinase lost its activity due to strong suicide inactivation caused by L-DOPA processing. In this case, the cost of the immobilized enzyme preparation is not overcome by its reuse over time, and native tyrosinase may be more economically feasible for a single use in L-DOPA production. The practical importance of the obtained results is that highly efficient hydroxylation of monophenols by tyrosinase can be obtained by selecting the proper reaction pH and is a compromise between complexation and enzyme reactivity. PMID:27711193

  16. Interrogating Surface Functional Group Heterogeneity of Activated Thermoplastics Using Super-Resolution Fluorescence Microscopy.

    PubMed

    ONeil, Colleen E; Jackson, Joshua M; Shim, Sang-Hee; Soper, Steven A

    2016-04-01

    We present a novel approach for characterizing surfaces utilizing super-resolution fluorescence microscopy with subdiffraction limit spatial resolution. Thermoplastic surfaces were activated by UV/O3 or O2 plasma treatment under various conditions to generate pendant surface-confined carboxylic acids (-COOH). These surface functional groups were then labeled with a photoswitchable dye and interrogated using single-molecule, localization-based, super-resolution fluorescence microscopy to elucidate the surface heterogeneity of these functional groups across the activated surface. Data indicated nonuniform distributions of these functional groups for both COC and PMMA thermoplastics with the degree of heterogeneity being dose dependent. In addition, COC demonstrated relative higher surface density of functional groups compared to PMMA for both UV/O3 and O2 plasma treatment. The spatial distribution of -COOH groups secured from super-resolution imaging were used to simulate nonuniform patterns of electroosmotic flow in thermoplastic nanochannels. Simulations were compared to single-particle tracking of fluorescent nanoparticles within thermoplastic nanoslits to demonstrate the effects of surface functional group heterogeneity on the electrokinetic transport process.

  17. Activities of the US-Japan Safety Monitor Joint Working Group

    SciTech Connect

    Richard L. Savercool; Lee C. Cadwallader

    2004-09-01

    This paper documents the activities of the US-Japan exchange in the area of personnel safety at magnetic and laser fusion experiments. A near-miss event with a visiting scientist to the US in 1992 was the impetus for forming the Joint Working Group on Fusion Safety. This exchnge has been under way for over ten years and has provided many safety insights for both US and Japanese facility personnel at national institutes and at universities. The background and activities of the Joint Working Group are described, including the facilities that have been visited for safety walkthroughs, the participants from both countries, and the main safety issues examined during visits. Based on these visits, some operational safety ideas to enhance experiment safety are given. The near-term future plans of the Safety Monitor Joint Working group are also discussed.

  18. Group intervention changes brain activity in bilingual language-impaired children.

    PubMed

    Pihko, Elina; Mickos, Annika; Kujala, Teija; Pihlgren, Annika; Westman, Martin; Alku, Paavo; Byring, Roger; Korkman, Marit

    2007-04-01

    This investigation assessed the effectiveness of a phonological intervention program on the brain functioning of bilingual Finnish 6- to 7-year-old preschool children diagnosed with specific language impairment (SLI). The intervention program was implemented by preschool teachers to small groups of children including children with SLI. A matched group of other bilingual children with SLI received a physical exercise program and served as a control group. Auditory evoked magnetic fields were measured before and after the intervention with an oddball paradigm. The brain activity recordings were followed by a behavioral discrimination test. Our results show that, in children with SLI, the positive intervention effect is reflected in plastic changes in the brain activity of the left and right auditory cortices.

  19. Communication: Active space decomposition with multiple sites: Density matrix renormalization group algorithm

    SciTech Connect

    Parker, Shane M.; Shiozaki, Toru

    2014-12-07

    We extend the active space decomposition method, recently developed by us, to more than two active sites using the density matrix renormalization group algorithm. The fragment wave functions are described by complete or restricted active-space wave functions. Numerical results are shown on a benzene pentamer and a perylene diimide trimer. It is found that the truncation errors in our method decrease almost exponentially with respect to the number of renormalization states M, allowing for numerically exact calculations (to a few μE{sub h} or less) with M = 128 in both cases. This rapid convergence is because the renormalization steps are used only for the interfragment electron correlation.

  20. Chloroplast Sulfhydryl Groups and the Light Activation of Fructose-1,6-Bisphosphatase 1

    PubMed Central

    Slovacek, Rudolf E.; Vaughn, Sharon

    1982-01-01

    Studies of isolated intact spinach (Spinacia oleracea L.) chloroplasts reveal that most of the available sulfhydryl groups are associated with stromal protein as opposed to a thylakoid membrane fraction under non-denaturing conditions. Increases in sulfhydryl content of approximately 50% occurred with illumination and could be correlated kinetically with a reductive activation of fructose-1,6-bisphosphatase during CO2-assimilation. Inhibition of linear electron flow with 3-(3,4-dichlorophenyl)-1,1-dimethylurea prevented light driven increases in both fructose-1,6-bisphosphatase activity and the relative sulfhydryl number. These results provide evidence for the operation of a reductive enzyme activating system in vivo. PMID:16662654

  1. Synthesis and hypoglycemic activity of 9-O-(lipophilic group substituted) berberine derivatives.

    PubMed

    Zhang, Shanshan; Wang, Xiaohong; Yin, Weicheng; Liu, Zhenbao; Zhou, Mi; Xiao, Daipeng; Liu, Yanfei; Peng, Dongming

    2016-10-01

    A series of 9-O-(lipophilic group substituted) berberine derivatives were synthesized and evaluated for their cytotoxicity and hypoglycemic activity against HepG2 cells. All the results indicated that most of the synthesized compounds exhibited lower cytotoxicity and a certain degree of hypoglycemic activity. Especially the compounds 5g and 5h displayed dramatically increased hypoglycemic activity compared with berberine, and the cytotoxicity maintained or even lower than berberine, indicating that they are potential candidates for new anti-type 2 diabetes mellitus drugs. PMID:27561717

  2. Theoretical study on the sequential hydroxylation of C82 fullerene based on Fukui function

    NASA Astrophysics Data System (ADS)

    Rodríguez-Zavala, J. G.; Tenorio, F. J.; Samaniego, Cuauhtemoc; Méndez-Barrientos, C. I.; Peña-Lecona, F. G.; Muñoz-Maciel, J.; Flores-Moreno, R.

    2011-07-01

    In the present work semi-empirical PM3 method and ab initio density-functional theory calculations were performed in carbon systems. The condensed Fukui function was calculated and HOMO-LUMO were visualised in order to study the sequence of hydroxylation of two isomers of C82 fullerene for the low coverage regime, with the formula C82(OH) x where x = 0 - 12. It was found that there was a formation of dangling bonds on structures with an odd number of hydroxyl groups on the fullerene surface, which suggests an enhanced reactivity of these molecules. Nevertheless, the coverings with an even number of groups tend to the reconstruction of π bonds, obtaining less reactive molecular structures. With the adsorption of the first group, a narrow HOMO-LUMO gap (1.28 eV) is observed in comparison with the C82(OH)2 system (1.70 eV), as is found in similar systems, such as C60 fullerenol [E.E. Fileti et al., Nanotechnology 19, 365703 (2008); J.G. Rodríguez-Zavala and R.A. Guirado-López, Phys. Rev. B 69, 075411 (2004)]. Through an analysis of the electronic structure to these coverings, a splitting of electronic energy levels in the structure with one hydroxyl group is observed, which could be one of the factors that causes the narrowing of the energy gap in this structure. On the other hand, with a coverage of 12 hydroxyl groups, the formation of an amphiphilic molecule, where the location of groups in one side of the C82 surface provides an hydrophilic character, is observed, while the uncovered part has an hydrophobic character. This could be important in the formation of Langmuir monolayers. Finally, it is shown that the precise distribution of the OH groups on the fullerene surface plays a crucial role in the electronic structure of the polyhydroxylated fullerenes.

  3. “Convivência” Groups: Building Active and Healthy Communities of Older Adults in Brazil

    PubMed Central

    Benedetti, Tânia R. Bertoldo; d'Orsi, Eleonora; Schwingel, Andiara; Chodzko-Zajko, Wojtek J.

    2012-01-01

    In old age, social groups can be a crucial component for health and well-being. In 2009-2010, a follow-up survey was carried out in Florianópolis, Brazil to understand the impact of a variety of programs established since 2002 that were designed to enhance social activities among the older adult population. This study employed two surveys within the population of older adults in Florianópolis. The first survey interviewed a total of 875 older adults in 2002, and the second survey involved 1,705 older adults between 2009 and 2010. By 2010, many new programs were offered in the community and the enrollment of older adults in social programs followed similar trends. “Convivência” groups stood out as extremely popular social groups among this population. This paper discusses some of the potential outcomes associated with participation in “convivência” groups. PMID:22830022

  4. Townes Group Activities from 1983-2000: Personal Recollections of William Danchi

    NASA Technical Reports Server (NTRS)

    Danchi, William C.

    2015-01-01

    I arrived in Berkeley in October 1983 as a post-doc, and my appointment was at the Space Sciences Laboratory (SSL). During that time the group was very large, with multiple activities led by Charlie himself and also by Senior Fellows such as John Lacy, Dan Jaffe, and Al Betz at the top of the hill at Space Sciences. Another significant contingent of the Townes group was housed in Birge Hall on campus, led by Reinhard Genzel when he was an Assistant Professor in the Physics Department. Although the group encompassed two separate locations, it functioned as one large group. Either we rode with Charlie up and down the hill, or (if we were concerned about our safety!) we took the bus.

  5. Activities of the OECD/NEA Expert Group on Assay Data for Spent Nuclear Fuel

    SciTech Connect

    Gauld, Ian C; Rugama, Yolanda

    2009-01-01

    Management of spent nuclear fuel is a key issue for many NEA member countries. In nuclear criticality safety, the decision of many countries to advance burnup credit as part of their licensing strategy has heightened recent interest in experimental data needed to validate computer codes used in burnup credit calculations. This paper discusses recent activities of an Expert Group on assay data, formed under the OECD/NEA/NSC/WPNCS (Working Party on Nuclear Criticality Safety) to help coordinate isotopic assay data activities and facilitate international collaboration between NEA member countries developing or implementing burnup credit methodologies. Recent activities of the Expert Group are described, focusing on the planned expansion of the Spent Fuel Isotopic Composition Database (SFCOMPO), and preparation of a state-of-the-art report on assay data that includes sections on recommended radiochemical analysis methods, techniques, and lessons learned from previous experiments.

  6. Enhanced Surfactant Adsorption on Activated Carbon through Manipulation of Surface Oxygen Groups

    NASA Astrophysics Data System (ADS)

    Collins, John; Qu, Deyang; Foster, Michelle

    2012-02-01

    Passive energy storage is a necessary component for balancing the lifecycle budget with new forms of green energy. The work presented describes how surface oxygen groups (SOG) on granulated activated carbon have been manipulated using Nitric Acid in a controlled, stepwise fashion. The structure and surface functionality of the activated carbon samples were characterized using DRIFTS, Raman Spectroscopy and Porosimetry. Total surface area was found to increase proportionally with the removal of heteroatom material, exposing previously insulated active sites responsible for SOG attachment. Broad oxide peaks were deconvoluted and analyzed, allowing for absolute identification of evolving functionality at each oxidation stage. SOGs were maximized on the third oxidation cycle with the presence of conjugated aromatic, phenol, lactone, and carboxylic acid groups. FSN Zonyl nonionic was applied to all oxidized samples at various concentrations. Total adsorbed surfactant was quantified for each concentration / oxidation scheme using attenuated total reflection. The relative quantity and polarity of chemisorbed surfactant were qualitatively assessed for each equilibrium concentration.

  7. Antibacterials. Synthesis and structure-activity studies of 3-aryl-2-oxooxazolidines. 1. The "B" group.

    PubMed

    Gregory, W A; Brittelli, D R; Wang, C L; Wuonola, M A; McRipley, R J; Eustice, D C; Eberly, V S; Bartholomew, P T; Slee, A M; Forbes, M

    1989-08-01

    The synthesis and structure/activity studies of the effect of varying the "B" group in a series of oxazolidinone antibacterials (I) are described. Two synthetic routes were used: (1) alkylation of aniline with glycidol followed by dialkyl carbonate heterocyclization to afford I (A = H, B = OH), whose arene ring was further elaborated by using electrophilic aromatic substitution methodology; (2) cycloaddition of substituted aryl isocyanates with epoxides to give A and B with a variety of values. I with B = OH or Br were converted to other "B" functionalities by using SN2 methodology. Antibacterial evaluation of compounds I with A = acetyl, isopropyl, methylthio, methylsulfinyl, methylsulfonyl, and sulfonamido and a variety of different "B" groups against Staphylococcus aureus and Enterococcus faecalis concluded that the compounds with B = aminoacyl, and particularly acetamido, were the most active of those examined in each A series, possessing MICs in the range of 0.5-4 micrograms/mL for the most active compounds described.

  8. Influences of the size and hydroxyl number of fullerenes/fullerenols on their interactions with proteins.

    PubMed

    Wu, Xian; Yang, Sheng-Tao; Wang, Haifang; Wang, Luyao; Hu, Wenxiang; Cao, Aoneng; Liu, Yuanfang

    2010-10-01

    In this study, we systematically investigated the interaction of fullerenes/fullerenols with model proteins using a widely used computational docking program Autodock 4.0. We found that pi-pi interaction existed in all the proteins-fullerene/fullerenol systems investigated here, and contributed greatly to the overall interaction energy. We also found that with the increase of the carbon cage size, the binding strength between proteins and fullerenes/fullerenols increased constantly. In addition, our results show that functionalization of fullerenes with polar groups, such as hydroxyl groups, decreases the binding between proteins and fullerene derivatives. In other words, the more hydroxyl groups on fullerenols, the weaker binding between proteins and fullerenols.

  9. Effect of group activities on health promotion for the community-dwelling elderly

    PubMed Central

    Fukasawa, Masako; Yamaguchi, Haruyasu

    2016-01-01

    Objective: In Japan, the Integrated Community Care System aims to support residents to live as independently as possible at home. Koreisya-Kyoshitsu and Fureaiikiiki salons are two types of group activities for community-dwelling elderly. We investigated effective ways of conducting such activities. Methods: We analyzed 96 subjects from 8 salons and 354 subjects from 10 Koreisya-Kyoshitsu. Self-completed questionnaires included the following: attributes, the Motor Fitness Scale (MFS), revised Philadelphia Geriatric Center Morale Scale (PGCMS), Measurement of Psychological Independence (MPI), instrumental activities of daily living (IADL), and self-rated health status (SRH). Follow-up assessment was conducted 6 months later. Representatives from 8 salons and staff members from 10 Koreisya-Kyoshitsu answered an additional questionnaire on management. Results: In Koreisya-Kyoshitsu, physical performance (MFS) (p = 0.007) and subjective well-being (PGCMS) (p = 0.001) improved significantly, whereas psychological independence (MPI) deteriorated significantly (p = 0.015). The MFS scores significantly improved in the sub-group with a high number of sessions (7 or more) (p = 0.043), as well as in the non-volunteer sub-group (p = 0.004). The PGCMS scores significantly improved in the sub-group with a high number of sessions (p < 0.001). The MPI scores significantly deteriorated in the sub-group with a low frequency of sessions (6 or less) and in the non-volunteer sub-group (p = 0.013 and p = 0.010, respectively). In salons, the frequency of going out decreased significantly (p = 0.049). Functional status (IADL) significantly improved in the “twice or more a month” sub-group (p = 0.046), whereas it significantly deteriorated in the “once a month” sub-group (p = 0.004). The proportion of volunteers/organizers in Koreisya-Kyoshitsu (23.4%) was significantly lower than that in salons (39.6%). Conclusion: The frequency (number) of sessions, but not the volunteer

  10. Adult total wellness: group differences based on sitting time and physical activity level

    PubMed Central

    2014-01-01

    Background An increasing body of evidence associates a high level of sitting time with poor health outcomes. The benefits of moderate to vigorous-intensity physical activities to various aspects of health are now well documented; however, individuals may engage in moderate-intensity physical activity for at least 30 minutes on five or more days of the week and still exhibit a high level of sitting time. This purpose of this study was to examine differences in total wellness among adults relative to high/low levels of sitting time combined with insufficient/sufficient physical activity (PA). The construct of total wellness incorporates a holistic approach to the body, mind and spirit components of life, an approach which may be more encompassing than some definitions of health. Methods Data were obtained from 226 adult respondents (27 ± 6 years), including 116 (51%) males and 110 (49%) females. Total PA and total sitting time were assessed with the International Physical Activity Questionnaire (IPAQ) (short-version). The Wellness Evaluation of Lifestyle Inventory was used to assess total wellness. An analysis of covariance (ANCOVA) was utilised to assess the effects of the sitting time/physical activity group on total wellness. A covariate was included to partial out the effects of age, sex and work status (student or employed). Cross-tabulations were used to show associations between the IPAQ derived high/low levels of sitting time with insufficient/sufficient PA and the three total wellness groups (i.e. high level of wellness, moderate wellness and wellness development needed). Results The majority of the participants were located in the high total sitting time and sufficient PA group. There were statistical differences among the IPAQ groups for total wellness [F (2,220) = 32.5 (p <0.001)]. A Chi-square test revealed a significant difference in the distribution of the IPAQ categories within the classification of wellness [χ2 (N = 226) = 54.5, p < .001

  11. Detection of enzyme activities and their relation to serotypes of bovine and human group B streptococci.

    PubMed

    Ekin, Ismail Hakki; Gurturk, Kemal; Ilhan, Ziya; Arabaci, Cigdem; Gulaydin, Ozgul

    2015-09-01

    Enzymatic properties of group B streptococci (GBS) serotypes from bovine milk and human routine vaginal specimens were investigated. Out of the 56 human and 66 bovine GBS, 35 and 30 could be classified serologically by a co-agglutination test with type-specific antisera, respectively. Hyaluronidase (HYAL), streptokinase (SK) and protease activities were detected using culture media. HYAL activity was observed mostly in typable human GBS, and serotypes Ia, Ic and II comprised 77.3% of the typable strains producing HYAL. Bovine GBS serotypes II, III and VII comprised 87.5% of typable bovine strains exhibiting HYAL activity. SK activity was detected only in three human GBS. Human GBS serotypes Ia, Ic, II, III, VII and almost all typable bovine GBS strains showed protease activity. β-D-glucosidase activity was frequently observed in human GBS, whereas N-acetyl-β-D-glucosaminidase activity was mostly detected in non-typable GBS from humans. These results indicate that different GBS serotypes could vary in their virulence properties, and bovine and human GBS isolates could not be differentiated by their enzyme activities. Use of the culture media appeared to be a simple-to-apply and useful method for the detection of extracellular enzyme activity such as HYAL, protease and SK. PMID:26297151

  12. A group II-activated ascending tract of lumbosacral origin in the cat spinal cord.

    PubMed Central

    Harrison, P J; Riddell, J S

    1990-01-01

    1. Electrophysiological investigations have revealed a population of ascending tract neurones originating in the lumbosacral enlargement, with input from group II muscle afferents of the cat hindlimb. 2. Single-unit microelectrode recordings were made in the lateral funiculus at L6, from the axons of thirty-four ascending tract neurones. All of the axons were antidromically activated by stimulation of the ipsilateral lateral funiculus at Th13 and, whenever tested (eight units), at C1. 3. Conduction velocities of the axons, between the L6 and Th13 segment, ranged from 33 to 92 m s-1 (mean 61 m s-1). 4. All of the ascending tract neurones were discharged following electrical stimulation of muscle nerves at group II strength, but not by weaker stimuli in the group I range. Most of the investigated neurones were excited by group II afferents of more than one muscle nerve. In addition, a proportion of the units tested could also be discharged by cutaneous and by joint afferents. 5. Responses to natural stimuli were investigated in eighteen ascending tract neurones discharged by electrical stimulation of group II afferents in the gastrocnemius-soleus (GS) and plantaris (P1) nerves which were dissected free in continuity with their muscles. Seven units were spontaneously active. Eight units responded to isometric contraction of the GS/P1 muscles with a discharge occurring mainly on the falling phase of muscle tension. Nine units increased their discharge frequency in response to stretching of the muscles and five units responded to mechanically probing the muscles with a blunt instrument. 6. The final termination sites of this group of ascending tract neurones has yet to be determined. Initial attempts (three units) to antidromically activate the neurones from the cerebellum have been unsuccessful. Other likely areas of termination in the brain stem are considered. PMID:2213583

  13. Assessing Activity and Location of Individual Laying Hens in Large Groups Using Modern Technology

    PubMed Central

    Siegford, Janice M.; Berezowski, John; Biswas, Subir K.; Daigle, Courtney L.; Gebhardt-Henrich, Sabine G.; Hernandez, Carlos E.; Thurner, Stefan; Toscano, Michael J.

    2016-01-01

    Simple Summary Tracking of individual animals within large groups is increasingly possible offering an exciting opportunity to researchers. Whereas previously only relatively indistinguishable groups of individual animals could be observed and combined into pen level data, we can now focus on individual actors and track their activities across time and space with minimal intervention and disturbance. We describe several tracking systems that are currently in use for laying hens and review each, highlighting their strengths and weaknesses, as well as environments or conditions for which they may be most suited, and relevant issues to fit the best technology for the intended purpose. Abstract Tracking individual animals within large groups is increasingly possible, offering an exciting opportunity to researchers. Whereas previously only relatively indistinguishable groups of individual animals could be observed and combined into pen level data, we can now focus on individual actors within these large groups and track their activities across time and space with minimal intervention and disturbance. The development is particularly relevant to the poultry industry as, due to a shift away from battery cages, flock sizes are increasingly becoming larger and environments more complex. Many efforts have been made to track individual bird behavior and activity in large groups using a variety of methodologies with variable success. Of the technologies in use, each has associated benefits and detriments, which can make the approach more or less suitable for certain environments and experiments. Within this article, we have divided several tracking systems that are currently available into two major categories (radio frequency identification and radio signal strength) and review the strengths and weaknesses of each, as well as environments or conditions for which they may be most suitable. We also describe related topics including types of analysis for the data and concerns

  14. Cellulose based hybrid hydroxylated adducts for polyurethane foams

    NASA Astrophysics Data System (ADS)

    De Pisapia, Laura; Verdolotti, Letizia; Di Mauro, Eduardo; Di Maio, Ernesto; Lavorgna, Marino; Iannace, Salvatore

    2012-07-01

    Hybrid flexible polyurethane foams (HPU) were synthesized by using a hybrid hydroxilated adduct (HHA) based on renewable resources. In particular the HHA was obtained by dispersing cellulose wastes in colloidal silica at room temperature, pressure and humidity. The colloidal silica was selected for its ability of modifying the cellulose structure, by inducing a certain "destructurization" of the crystalline phase, in order to allow cellulose to react with di-isocyanate for the final synthesis of the polyurethane foam. In fact, cellulose-polysilicate complexes are engaged in the reaction with the isocyanate groups. This study provides evidence of the effects of the colloidal silica on the cellulose structure, namely, a reduction of the microfiber cellulose diameter and the formation of hydrogen bonds between the polysilicate functional groups and the hydroxyl groups of the cellulose, as assessed by IR spectroscopy and solid state NMR. The HHA was added to a conventional polyol in different percentages (between 5 and 20%) to synthesize HPU in presence of catalysts, silicone surfactant and diphenylmethane diisocyanate (MDI). The mixture was expanded in a mold and cured for two hours at room temperature. Thermal analysis, optical microscopy and mechanical tests were performed on the foams. The results highlighted an improvement of thermal stability and a decrease of the cell size with respect neat polyurethane foam. Mechanical tests showed an improvement of the elastic modulus and of the damping properties with increasing HHA amount.

  15. Development, Evaluation and Implementation of Chief Complaint Groupings to Activate Data Collection

    PubMed Central

    Bajaj, L.; Hoffman, J.; Alessandrini, E.; Ballard, D. W.; Norris, R.; Tzimenatos, L.; Swietlik, M.; Tham, E.; Grundmeier, R. W.; Kuppermann, N.; Dayan, P. S.

    2015-01-01

    Summary Background Overuse of cranial computed tomography scans in children with blunt head trauma unnecessarily exposes them to radiation. The Pediatric Emergency Care Applied Research Network (PECARN) blunt head trauma prediction rules identify children who do not require a computed tomography scan. Electronic health record (EHR) based clinical decision support (CDS) may effectively implement these rules but must only be provided for appropriate patients in order to minimize excessive alerts. Objectives To develop, implement and evaluate site-specific groupings of chief complaints (CC) that accurately identify children with head trauma, in order to activate data collection in an EHR. Methods As part of a 13 site clinical trial comparing cranial computed tomography use before and after implementation of CDS, four PECARN sites centrally developed and locally implemented CC groupings to trigger a clinical trial alert (CTA) to facilitate the completion of an emergency department head trauma data collection template. We tested and chose CC groupings to attain high sensitivity while maintaining at least moderate specificity. Results Due to variability in CCs available, identical groupings across sites were not possible. We noted substantial variability in the sensitivity and specificity of seemingly similar CC groupings between sites. The implemented CC groupings had sensitivities greater than 90% with specificities between 75–89%. During the trial, formal testing and provider feedback led to tailoring of the CC groupings at some sites. Conclusions CC groupings can be successfully developed and implemented across multiple sites to accurately identify patients who should have a CTA triggered to facilitate EHR data collection. However, CC groupings will necessarily vary in order to attain high sensitivity and moderate-to-high specificity. In future trials, the balance between sensitivity and specificity should be considered based on the nature of the clinical condition

  16. N-Nitrosobenzylmethylamine hydroxylation and coumarin 7-hydroxylation: catalysis by rat esophageal microsomes and cytochrome P450 2A3 and 2A6 enzymes.

    PubMed

    von Weymarn, L B; Felicia, N D; Ding, X; Murphy, S E

    1999-12-01

    N-Nitrosobenzylmethylamine (NBzMA) is a potent and selective esophageal carcinogen in the rat and may be a causative agent for human esophageal cancer. This nitrosamine, like most, must be metabolically activated to exert its carcinogenic potential. NBzMA may be metabolized by P450-catalyzed methyl or methylene hydroxylation; the latter is believed to be the activation pathway. The sensitivity of the esophagus to NBzMA-induced tumorigenesis is believed to be due, at least in part, to the presence of efficient P450 catalysts in this tissue. However, while it was reported almost 20 years ago that the rat esophagus catalyzes the methylene hydroxylation of NBzMA, the P450 that catalyzes this reaction has yet to be identified. We report here that human P450 2A6 and the closely related extrahepatic rat enzyme P450 2A3 both efficiently catalyze NBzMA methylene hydroxylation, characterized as benzaldehyde formation. The catalytic efficiency of P450 2A3 in this reaction was 3-fold greater than that of P450 2A6, 7.6 (K(m) = 0.63 +/- 0.18 microM and the V(max) = 4.8 nmol min(-)(1) nmol of P450(-)(1)) versus 2.3 (K(m) = 6.7 +/- 2.9 microM and the V(max) = 15.7 nmol min(-)(1) nmol of P450(-)(1)), respectively. Both enzymes catalyzed methylene hydroxylation at least 4-fold more efficiently than methyl hydroxylation. In addition, P450 2A6, but not P450 2A3, catalyzed benzyl ring hydroxylation, generating N-(p-hydroxybenzyl)methylamine. The identity of this metabolite was confirmed by synthesis of a standard and LC/MS and LC/MS/MS analysis. P450 2A6 is an efficient coumarin 7-hydroxylase, and we report here that P450 2A3 is an equally good catalyst of this reaction (K(m) = 1. 7 +/- 0.41 microM and V(max) = 1.7 +/- 0.08 nmol min(-)(1) nmol of P450(-)(1)). Rat esophageal microsomes (REM), like P450 2A3, were efficient catalysts of NBzMA methylene hydroxylation. However, in contrast to P450 2A3, the major product of this reaction was the product of benzaldehyde oxidation, benzoic

  17. Glutathione conjugation of busulfan produces a hydroxyl radical-trapping dehydroalanine metabolite.

    PubMed

    Peer, Cody J; Younis, Islam R; Leonard, Stephen S; Gannett, Peter M; Minarchick, Valerie C; Kenyon, Allison J; Rojanasakul, Yon; Callery, Patrick S

    2012-12-01

    The Phase 2 drug metabolism of busulfan yields a glutathione conjugate that undergoes a β-elimination reaction. The elimination product is an electrophilic metabolite that is a dehydroalanine-containing tripeptide, γ-glutamyldehydroalanylglycine (EdAG). In the process, glutathione lacks thiol-related redox properties and gains a radical scavenging dehydroalanine group. EdAG scavenged hydroxyl radical generated in the Fenton reaction in a concentration-dependent manner was monitored by electron paramagnetic resonance (EPR) spectroscopy. The apparent rate of hydroxyl radical scavenging was in the same range as published values for known antioxidants, including N-acyl dehydroalanines. A captodatively stabilized carbon-centered radical intermediate was spin trapped in the reaction of EdAG with hydroxyl radical. The proposed structure of a stable product in the Fenton reaction with EdAG was consistent with that of a γ-glutamylserylglycyl dimer. Observation of the hydroxyl trapping properties of EdAG suggests that the busulfan metabolite EdAG may contribute to or mitigate redox-related cytotoxicity associated with the therapeutic use of busulfan, and reaffirms indicators that support a role in free radical biology for dehydroalanine-containing peptides and proteins.

  18. Omega-hydroxylation of phytanic acid in rat liver microsomes: implications for Refsum disease.

    PubMed

    Komen, J C; Duran, M; Wanders, R J A

    2004-07-01

    The 3-methyl-branched fatty acid phytanic acid is degraded by the peroxisomal alpha-oxidation route because the 3-methyl group blocks beta-oxidation. In adult Refsum disease (ARD), peroxisomal alpha-oxidation is defective, which is caused by mutations in the gene coding for phytanoyl-CoA hydroxylase in the majority of ARD patients. As a consequence, phytanic acid accumulates in tissues and body fluids. This study focuses on an alternative route of phytanic acid degradation, omega-oxidation. The first step in omega-oxidation is hydroxylation at the omega-end of the fatty acid, catalyzed by a member of the cytochrome P450 multienzyme family. To study this first step, the formation of hydroxylated intermediates was studied in rat liver microsomes incubated with phytanic acid and NADPH. Two hydroxylated metabolites of phytanic acid were formed, omega- and (omega-1)-hydroxyphytanic acid (ratio of formation, 5:1). The formation of omega-hydroxyphytanic acid was NADPH dependent and inhibited by imidazole derivatives. These results indicate that phytanic acid undergoes omega-hydroxylation in rat liver microsomes and that an isoform of cytochrome P450 catalyzes the first step of phytanic acid omega-oxidation.

  19. Radiation-induced destruction of hydroxyl-containing amino acids and dipeptides

    NASA Astrophysics Data System (ADS)

    Sladkova, А. А.; Sosnovskaya, А. А.; Edimecheva, I. P.; Shadyro, О. I.

    2012-12-01

    The yields of molecular products resulting from radiolysis of hydroxyl-containing amino acids and dipeptides under various conditions were determined. The possibility of a new radiation-induced destruction pathway has been shown for serine and threonine, as well as for the dipeptides having residues of these amino acids at the N-terminal part of the respective molecule. This process includes formation of N-centered radicals from the starting molecules followed by their decomposition with elimination of side substituents. On radiolysis, serine and threonine were also shown to undergo free-radical destruction to form acetaldehyde and acetone, respectively. A mechanism has been proposed including consecutive stages of fragmentation of α-hydroxyl-containing carbon-centered radicals with elimination of ammonia and decomposition of the secondary radicals with elimination of CO2. The yields of CO2 obtained on radiolysis of serine and threonine were significantly higher (except for solutions at pH 12) than those for alanine and valine, which have no hydroxyl groups in their structures. The obtained data indicate that the hydroxyl-containing amino acids occupy a special place among other amino acids as regards the variety of radiation-induced reactions which they may undergo due to their structural features.

  20. Rh D blood group conversion using transcription activator-like effector nucleases.

    PubMed

    Kim, Young-Hoon; Kim, Hyun O; Baek, Eun J; Kurita, Ryo; Cha, Hyuk-Jin; Nakamura, Yukio; Kim, Hyongbum

    2015-06-16

    Group O D-negative blood cells are universal donors in transfusion medicine and methods for converting other blood groups into this universal donor group have been researched. However, conversion of D-positive cells into D-negative is yet to be achieved, although conversion of group A or B cells into O cells has been reported. The Rh D blood group is determined by the RHD gene, which encodes a 12-transmembrane domain protein. Here we convert Rh D-positive erythroid progenitor cells into D-negative cells using RHD-targeting transcription activator-like effector nucleases (TALENs). After transfection of TALEN-encoding plasmids, RHD-knockout clones are obtained. Erythroid-lineage cells differentiated from these knockout erythroid progenitor cells do not agglutinate in the presence of anti-D reagents and do not express D antigen, as assessed using flow cytometry. Our programmable nuclease-induced blood group conversion opens new avenues for compatible donor cell generation in transfusion medicine.

  1. Towards a common framework for assessing the activity and associations of groups who sexually abuse children

    PubMed Central

    Cockbain, Ella; Brayley, Helen; Sullivan, Joe

    2013-01-01

    Extensive social psychological research emphasises the importance of groups in shaping individuals’ thoughts and actions. Within the child sexual abuse (CSA) literature criminal organisation has been largely overlooked, with some key exceptions. This research was a novel collaboration between academia and the UK's Child Exploitation and Online Protection Centre (CEOP). Starting from the premise that the group is, in itself, a form of social situation affecting abuse, it offers the first systematic situational analysis of CSA groups. In-depth behavioural data from a small sample of convicted CSA group-offenders (n = 3) were analysed qualitatively to identify factors and processes underpinning CSA groups’ activities and associations: group formation, evolution, identity and resources. The results emphasise CSA groups’ variability, fluidity and dynamism. The foundations of a general framework are proposed for researching and assessing CSA groups and designing effective interventions. It is hoped that this work will stimulate discussion and development in this long-neglected area of CSA, helping to build a coherent knowledge-base. PMID:26494978

  2. The epidemiology of walking for exercise: implications for promoting activity among sedentary groups.

    PubMed Central

    Siegel, P Z; Brackbill, R M; Heath, G W

    1995-01-01

    The relative contribution of walking to overall leisure-time physical activity participation rates was studied among respondents from the 45 states that participated in the 1990 Behavioral Risk Factor Surveillance System (n = 81,557). The percentages of low income, unemployed, and obese persons who engaged in leisure-time physical activity (range = 51.1% to 57.7%) were substantially lower than the percentage among the total adult population (70.3%). In contrast, the prevalence of walking for exercise among these sedentary groups (range = 32.5% to 35.9%) was similar to that among the total population (35.6%). Walking appears to be an acceptable, accessible exercise activity, especially among population subgroups with a low prevalence of leisure-time physical activity. PMID:7733433

  3. Physical Activity and Sedentary Behavior in an Ethnically Diverse Group of South African School Children

    PubMed Central

    McVeigh, Joanne; Meiring, Rebecca

    2014-01-01

    Few studies have examined physical activity and inactivity levels in an urban South African setting across 12 years of formal schooling. This information is important for implementing strategies to curb increasing trends of physical inactivity and related negative consequences, especially in low to middle income countries facing multiple challenges on overburdened health care systems. We examined levels of physical activity and sedentary behaviour cross-sectionally over 12 school years from childhood to adolescence in Black, White and Indian boys and girls. The aim of our study was to describe gender and race related patterns of physical and sedentary activity levels in a sample of South African children and to determine whether there were associations between these variables and body mass status. Physical activity questionnaires, previously validated in a South African setting, were used to gather information about activity and sedentary behaviours among 767 Black, White and Indian children (5-18 years of age) across the 12 grades of formal schooling. Body mass and height were also measured. Time spent in moderate-vigorous physical activity declined over the school years for all race groups and was consistently lower for girls than boys (p = 0.03), while time spent in sedentary activity increased with increasing grade (p < 0.001) for boys and girls and across all race groups. Associations between physical activity and body mass were observed for White children (r = -0.22, p < 0.001), but not for Black and Indian children (p > 0.05) whereas time spent in sedentary activities was significantly and positively correlated with body mass across all race groups: Indian (r = 0.25, p < 0.001), White (r = 0.22, p < 0.001) and Black (r = 0.37, p = 0.001). The strength of the associations was similar for boys and girls. Black and Indian children were less physically active than their white peers (p < 0.05), and Black children also spent more time in sedentary activity (p < 0

  4. Petroleum films exposed to sunlight produce hydroxyl radical.

    PubMed

    Ray, Phoebe Z; Tarr, Matthew A

    2014-05-01

    Sunlight exposed oil films on seawater or pure water produced substantial amounts of hydroxyl radical as a result of irradiation. Oil was collected from the surface of the Gulf of Mexico following the Deepwater Horizon spill and exposed to simulated sunlight in thin films over water. Photochemical production of hydroxyl radical was measured with benzoic acid as a selective chemical probe in the aqueous layer. Total hydroxyl radical formation was studied using high benzoic acid concentrations and varying exposure time. The total amount of hydroxyl radical produced in 24 h irradiations of thin oil films over Gulf of Mexico water and pure water were 3.7×10(-7) and 4.2×10(-7) moles respectively. Steady state concentrations of hydroxyl radical were measured using a competition kinetics approach. Hydroxyl radical concentrations of 1.2×10(-16) to 2.4×10(-16) M were observed for seawater and pure water under oil films. Titanium dioxide (TiO2) nanomaterials were added to the system in an effort to determine if the photocatalyst would enhance oil photodegradation. The addition of TiO2 nanoparticles dramatically changed the observed formation rate of hydroxyl radical in the systems with NP water at pH 3, showing increased formation rate in many cases. With photocatalyst, the steady state concentration of radical decreased, predominantly due to an increase in the hydroxyl radical scavenging rate with oxide present. This study illustrates that oil is a strong and important source of hydroxyl radical when exposed to sunlight. The fate of oil and other dissolved species following oil spills will be heavily dependent on the formation and fate of hydroxyl radical.

  5. Petroleum films exposed to sunlight produce hydroxyl radical.

    PubMed

    Ray, Phoebe Z; Tarr, Matthew A

    2014-05-01

    Sunlight exposed oil films on seawater or pure water produced substantial amounts of hydroxyl radical as a result of irradiation. Oil was collected from the surface of the Gulf of Mexico following the Deepwater Horizon spill and exposed to simulated sunlight in thin films over water. Photochemical production of hydroxyl radical was measured with benzoic acid as a selective chemical probe in the aqueous layer. Total hydroxyl radical formation was studied using high benzoic acid concentrations and varying exposure time. The total amount of hydroxyl radical produced in 24 h irradiations of thin oil films over Gulf of Mexico water and pure water were 3.7×10(-7) and 4.2×10(-7) moles respectively. Steady state concentrations of hydroxyl radical were measured using a competition kinetics approach. Hydroxyl radical concentrations of 1.2×10(-16) to 2.4×10(-16) M were observed for seawater and pure water under oil films. Titanium dioxide (TiO2) nanomaterials were added to the system in an effort to determine if the photocatalyst would enhance oil photodegradation. The addition of TiO2 nanoparticles dramatically changed the observed formation rate of hydroxyl radical in the systems with NP water at pH 3, showing increased formation rate in many cases. With photocatalyst, the steady state concentration of radical decreased, predominantly due to an increase in the hydroxyl radical scavenging rate with oxide present. This study illustrates that oil is a strong and important source of hydroxyl radical when exposed to sunlight. The fate of oil and other dissolved species following oil spills will be heavily dependent on the formation and fate of hydroxyl radical. PMID:24405967

  6. Plane-wave density functional theory investigation of adsorption of 2,4,6-trinitrotoluene on Al-hydroxylated (0001) surface of (4 × 4) α-alumina.

    PubMed

    Shukla, Manoj K; Hill, Frances

    2014-10-15

    This article reports the results of the theoretical investigation of adsorption of 2,4,6-trinitrotoluene (TNT) on Al-hydroxylated (0001) surface of (4 × 4) α-alumina (α-Al2O3) using plane-wave Density Functional Theory. Sixteen water molecules were used to hydroxylate the alumina surface. The Perdew-Burke-Ernzerhof functional and the recently developed van der Waals functional (vdW-DF2) were used. The interaction of electron with core was accounted using the Vanderbilt ultrasoft pseudopotentials. It was found that hydroxylation has significant influence on the geometry of alumina and such changes are prominent up to few layers from the surface. Particularly, due to the Al-hydroxylation the oxygen layers are decomposed into sublayers and such partitioning becomes progressively weaker for interior layers. Moreover, the nature of TNT adsorption interaction is changed from covalent type on the pristine alumina surface to hydrogen-bonding interaction on the Al-hydroxylated alumina surface. TNT in parallel orientation forms several hydrogen bonds compared to that in the perpendicular orientation with hydroxyl groups of the Al-hydroxylated alumina surface. Therefore, the parallel orientation will be present in the adsorption of TNT on Al-hydroxylated (0001) surface of α-alumina. Further, the vdW-DF2 van der Waals functional was found to be most suitable and should be used for such surface adsorption investigation.

  7. Antimalarial and Antileishmanial Activities of Histone Deacetylase Inhibitors with Triazole-Linked Cap Group

    PubMed Central

    Patil, Vishal; Guerrant, William; Chen, Po C.; Gryder, Berkley; Benicewicz, Derek B.; Khan, Shabana I.; Tekwani, Babu L.; Oyelere, Adegboyega K.

    2009-01-01

    Histone deacetylase inhibitors (HDACi) are endowed with plethora of biological functions including anti-proliferative, anti-inflammatory, anti-parasitic, and cognition-enhancing activities. Parsing the structure–activity relationship (SAR) for each disease condition is vital for long-term therapeutic applications of HDACi. We report in the present study specific cap group substitution patterns and spacer-group chain lengths that enhance the antimalarial and antileishmanial activity of aryltriazolylhydroxamates-based HDACi. We identified many compounds that are several folds selectively cytotoxic to the plasmodium parasites compared to standard HDACi. Also, a few of these compounds have antileishmanial activity that rivals that of miltefosine, the only currently available oral agent against visceral leishmaniasis. The anti-parasite properties of several of these compounds tracked well with their anti-HDAC activities. The results presented here provide further evidence on the suitability of HDAC inhibition as a viable therapeutic option to curb infections caused by apicomplexan protozoans and trypanosomatids. PMID:19914074

  8. Design, synthesis, and antifungal activities of novel triazole derivatives containing the benzyl group

    PubMed Central

    Xu, Kehan; Huang, Lei; Xu, Zheng; Wang, Yanwei; Bai, Guojing; Wu, Qiuye; Wang, Xiaoyan; Yu, Shichong; Jiang, Yuanying

    2015-01-01

    In previous studies undertaken by our group, a series of 1-(1H-1,2,4-triazole-1-yl)-2-(2,4-difluorophenyl)-3-substituted-2-propanols (1a–r), which were analogs of fluconazole, was designed and synthesized by click chemistry. In the study reported here, the in vitro antifungal activities of all the target compounds were evaluated against eight human pathogenic fungi. Compounds 1a, 1q, and 1r showed the more antifungal activity than the others. PMID:25792806

  9. Surveillance and maintenance activities of waste area groupings at Oak Ridge National Laboratory

    SciTech Connect

    Ford, M.K.; Holder, L. Jr.; Jones, R.G.

    1991-12-01

    Surveillance and maintenance (S M) of 75 sites were conductd by the Remedial Action Section for the Environmental Restoration Program for surplus facilities and sites contaminated with radioactive materials and/or hazardous chemicals. S M activities on these sites were conducted from the end of their operating life until final facility disposal or site stabilization. The objectives of the Waste Area Grouping S M Program are met by maintaining a program of routine S M as well as by implementing interim corrective maintenance when deemed necessary as a result of site surveillance. This report briefly presents this program's activities and includes tables indicating tank levels and dry well data for FY 1991.

  10. Searching for a One-Step Bioprocess for the Production of Hydroxyl Fatty Acids and Hydroxyl Oils from Soybean Oil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soybean oil is produced domestically in large supply, averaging over 20 billion pounds per year with an annual carryover of more than one billion pounds. It is important to find new uses for this surplus soybean oil. Hydroxyl fatty acids and hydroxyl oils are platform materials for specialty chemi...

  11. Bis(ferrocenyl)polymethine cations. A prototype molecular wire with redox-active end groups

    SciTech Connect

    Tolbert, L.M.; Zhao, X.; Ding, Y.; Bottomley, L.A.

    1995-12-27

    We have previously provided evidence for solitonic behavior in polymethines using {alpha}{omega}-diphenylpolyenyl anions (DPN{sup -}, X = Ph) and {alpha}{omega}-dipyridocyanines (DPyN{sup +}, X = py-CH{sub 3}). We now extend this approach to molecular wires involving polymethines with redox-active end groups. In this communication, we report the synthesis and characterization of {alpha}{omega}-bis(ferrocenyl)polymethine cations (acronym DFcN{sup +}, X = C{sub 5}H{sub 5}) as part of our systematic investigation of solitonic behavior in molecules (`solitons in a box`). Ferrocene end groups provide stable, low-potential redox-active termini and allow strong coupling of the redox centers with the polyene chain. The first two members of this series (DFcL{sup +}, DFc3{sup +}) were generated according to literature methods. The remaining members were synthesized through conventional Wittig methodology. 20 refs., 3 figs., 2 tabs.

  12. Syntheses and Characterization of Chiral Arm Liquid Crystals--Containing Active Group

    NASA Astrophysics Data System (ADS)

    Jia, Ying; Zhang, Fang-Di; He, Xiao-Zhi

    2016-05-01

    A new series of chiral two-arm dopant containg active group were first synthesized. Four precursors of C1~C4 were obtained at first and then were esterized separately with isosorbide and got four two-arm liquid crystals (MC1~MC4). The chemical structures and LC properties of the liquid crystalline molecule were measured by spectrum and thermal analysis techniques. XRD curves of MC1~MC4 samples only showed broad peaks at wide-angle, no sharp peak was seen for all the samples. The results showed that MC1~MC4 appeared cholesteric phase with oily streak texture or lined texture and finger print texture. Cholesteric phase was successfully induced by isosorbide. The different active group of two arm liquid crystal and chiral core had effects on their liquid crystalline properties.

  13. Chlorosulfonation of polystyrene substrates for bioanalytical assays: distribution of activated groups at the surface.

    PubMed

    del Prado, Anselmo; Briz, Nerea; Navarro, Rodrigo; Pérez, Mónica; Gallardo, Alberto; Reinecke, Helmut

    2012-12-01

    In this work the activation of transparent PS substrates by chlorosulfonation is described and their distribution in the subsurface region is analyzed. For this purpose XPS, FTIR-ATR and colorimetry have been used. It is shown that the electrophilic aromatic substitution of polystyrene in pure chlorosulfonic acid is extremely quick with complete surface coverage by chlorosulfonic groups achieved after only a 10 minute reaction time at -10 °C. It is further demonstrated that the reaction is very surface selective and that even after reaction times as long as 3 hours, the modification is limited to a layer with a thickness of less than one micron. The activated PS substrates can be further functionalized in a second step with carboxylic groups. Due to the excellent optical transparency that the samples maintain upon modification, the modified systems were successfully probed for use in ELISA assays.

  14. Default-Mode Network Activity Identified by Group Independent Component Analysis

    NASA Astrophysics Data System (ADS)

    Liu, Conghui; Zhuang, Jie; Peng, Danling; Yu, Guoliang; Yang, Yanhui

    Default-mode network activity refers to some regional increase in blood oxygenation level-dependent (BOLD) signal during baseline than cognitive tasks. Recent functional imaging studies have found co-activation in a distributed network of cortical regions, including ventral anterior cingulate cortex (vACC) and posterior cingulate cortex (PPC) that characterize the default mode of human brain. In this study, general linear model and group independent component analysis (ICA) were utilized to analyze the fMRI data obtained from two language tasks. Both methods yielded similar, but not identical results and detected a resting deactivation network at some midline regions including anterior and posterior cingulate cortex and precuneus. Particularly, the group ICA method segregated functional elements into two separate maps and identified ventral cingulate component and fronto-parietal component. These results suggest that these two components might be linked to different mental function during "resting" baseline.

  15. Microbial Baeyer-Villiger oxidation of 5α-steroids using Beauveria bassiana. A stereochemical requirement for the 11α-hydroxylation and the lactonization pathway.

    PubMed

    Świzdor, Alina; Panek, Anna; Milecka-Tronina, Natalia

    2014-04-01

    Beauveria bassiana KCH 1065, as was recently demonstrated, is unusual amongst fungal biocatalysts in that it converts C19 3-oxo-4-ene and 3β-hydroxy-5-ene as well as 3β-hydroxy-5α-saturated steroids to 11α-hydroxy ring-D lactones. The Baeyer-Villiger monooxygenase (BVMO) of this strain is distinguished from other enzymes catalyzing BVO of steroidal ketones by the fact that it oxidizes solely substrates with 11α-hydroxyl group. The current study using a series of 5α-saturated steroids (androsterone, 3α-androstanediol and androstanedione) has highlighted that a small change of the steroid structure can result in significant differences of the metabolic fate. It was found that the 3α-stereochemistry of hydroxyl group restricted "normal" binding orientation of the substrate within 11α-hydroxylase and, as a result, androsterone and 3α-androstanediol were converted into a mixture of 7β-, 11α- and 7α-hydroxy derivatives. Hydroxylation of androstanedione occurred only at the 11α-position, indicating that the 3-oxo group limits the alternative binding orientation of the substrate within the hydroxylase. Only androstanedione and 3α-androstanediol were metabolized to hydroxylactones. The study uniquely demonstrated preference for oxidation of equatorial (11α-, 7β-) hydroxyketones by BVMO from B. bassiana. The time course experiments suggested that the activity of 17β-HSD is a factor determining the amount of produced ring-D lactones. The obtained 11α-hydroxylactones underwent further transformations (oxy-red reactions) at C-3. During conversion of androstanedione, a minor dehydrogenation pathway was observed with generation of 11α,17β-dihydroxy-5α-androst-1-en-3-one. The introduction of C1C2 double bond has been recorded in B. bassiana for the first time.

  16. Control of Surface Functional Groups on Pertechntate Sorption on Activated Carbon

    SciTech Connect

    Y. Wang; H. Gao; R. Yeredla; H. Xu; M. Abrecht; G.D. Stasio

    2006-07-05

    {sup 99}Tc is highly soluble and poorly adsorbed by natural materials under oxidizing conditions, thus being of particular concern for radioactive waste disposal. Activated carbon can potentially be used as an adsorbent for removing Tc from aqueous solutions. We have tested six commercial activated carbon materials for their capabilities for sorption of pertechnetate (TcO{sub 4}{sup -}). The tested materials can be grouped into two distinct types: Type I materials have high sorption capabilities with the distribution coefficients (K{sub d}) varying from 9.5 x 10{sup 5} to 3.2 x 10{sup 3} mL/g as the pH changes from 4.5 to 9.5, whereas type II materials have relatively low sorption capabilities with K{sub d} remaining more or less constant (1.1 x 10{sup 3} - 1.8 x 10{sup 3} mL/g) over a similar pH range. The difference in sorption behavior between the two types of materials is attributed to the distribution of surface functional groups. The predominant surface groups are identified to be carboxylic and phenolic groups. The carboxylic group can be further divided into three subgroups A, B, and C in the order of increasing acidity. The high sorption capabilities of type I materials are found to be caused by the presence of a large fraction of carboxylic subgroups A and B, while the low sorption capabilities of type II materials are due to the exclusive presence of phenolic and carboxylic subgroup C. Therefore, the performance of activated carbon for removing TcO{sub 4}{sup -} can be improved by enhancing the formation of carboxylic subgroups A and B during material processing.

  17. Transatlantic Consensus Group on active surveillance and focal therapy for prostate cancer

    PubMed Central

    Ahmed, Hashim U.; Akin, Oguz; Coleman, Jonathan A.; Crane, Sarah; Emberton, Mark; Goldenberg, Larry; Hricak, Hedvig; Kattan, Mike W.; Kurhanewicz, John; Moore, Caroline M.; Parker, Chris; Polascik, Thomas J.; Scardino, Peter; van As, Nicholas; Villers, Arnauld

    2013-01-01

    OBJECTIVE To reach consensus on key issues for clinical practice and future research in active surveillance and focal therapy in managing localized prostate cancer. PATIENTS AND METHODS A group of expert urologists, oncologists, radiologists, pathologists and computer scientists from North America and Europe met to discuss issues in patient population, interventions, comparators and outcome measures to use in both tissue-preserving strategies of active surveillance and focal therapy. Break-out sessions were formed to provide agreement or highlight areas of disagreement on individual topics which were then collated by a writing group into statements that formed the basis of this report and agreed upon by the whole Transatlantic Consensus Group. RESULTS The Transatlantic group propose that emerging diagnostic tools such as precision imaging and transperineal prostate mapping biopsy can improve prostate cancer care. These tools should be integrated into prostate cancer management and research so that better risk stratification and more effective treatment allocation can be applied. The group envisaged a process of care in which active surveillance, focal therapy, and radical treatments lie on a continuum of complementary therapies for men with a range of disease grades and burdens, rather than being applied in the mutually exclusive and competitive way they are now. CONCLUSION The changing landscape of prostate cancer epidemiology requires the medical community to re-evaluate the entire prostate cancer diagnostic and treatment pathway in order to minimize harms resulting from over-diagnosis and over-treatment. Precise risk stratification at every point in this pathway is required alongside paradigm shifts in our thinking about what constitutes cancer in the prostate. PMID:22077593

  18. Control of pertechnetate sorption on activated carbon by surface functional groups.

    PubMed

    Wang, Yifeng; Gao, Huizhen; Yeredla, Rakesh; Xu, Huifang; Abrecht, Mike

    2007-01-15

    The isotope 99Tc is highly soluble and poorly adsorbed by natural materials under oxidizing conditions, thus being of particular concern for radioactive waste disposal. Activated carbon can potentially be used as an adsorbent for removing Tc from aqueous solutions. We have tested six commercial activated carbon materials for their capabilities for sorption of pertechnetate (TcO4-). The tested materials can be grouped into two distinct types: Type I materials have high sorption capabilities with the distribution coefficients (Kd) varying from 9.5 x 10(5) to 3.2 x 10(3) ml/g as the pH changes from 4.5 to 9.5, whereas type II materials have relatively low sorption capabilities with Kd remaining more or less constant (1.1 x 10(3)-1.8 x 10(3) ml/g) over a similar pH range. The difference in sorption behavior between the two types of materials is attributed to the distribution of surface functional groups. The predominant surface groups are identified as carboxylic and phenolic groups. The carboxylic group can be further divided into three subgroups, A, B, and C, in the order of increasing acidity. The high sorption capabilities of type I materials are found to be caused by the presence of a large fraction of carboxylic subgroups A and B, while the low sorption capabilities of type II materials are due to the exclusive presence of phenolic and carboxylic subgroup C. Therefore, the performance of activated carbon for removing TcO4- can be improved by enhancing the formation of carboxylic subgroups A and B during materials processing.

  19. The functional importance of blood group-active molecules in human red blood cells.

    PubMed

    Anstee, D J

    2011-01-01

    Antigens of 23 of the 30 human blood group systems are defined by the amino acid sequence of red cell membrane proteins. The antigens of DI, RH, RHAG, MNS, GE and CO systems are carried on blood group-active proteins (Band 3, D and CE polypeptides, RhAG, Glycophorins A and B, Glycophorins C and D and Aquaporin 1, respectively) which are expressed at high levels (>200,000 copies/red cell). These major proteins contribute to essential red cell functions either directly as membrane transporters and by providing linkage to the underlying red cell skeleton or by facilitating the membrane assembly of the protein complexes involved in these processes. The proteins expressing antigens of the remaining 17 blood group systems are much less abundant (<20,000 copies/red cell) and their functional importance for the circulating red cell is largely unknown. Human gene knock-outs (null phenotypes) have been described for many of these minor blood group-active proteins, but only absence of Kx glycoprotein has been clearly linked with pathology directly related to the function of circulating red cells. Recent evidence suggesting the normal quality control system for glycoprotein synthesis is altered during the latter stages of red cell production raises the possibility that many of these low abundance blood group-active proteins are vestigial. In sickle cell disease and polycythaemia vera, elevated Lutheran glycoprotein expression may contribute to pathology. Dyserythropoiesis with reduced antigen expression can result from mutations in the erythroid transcription factors GATA-1 and EKLF.

  20. Synthesis, anticancer activity and toxicity of a water-soluble 4S,5S-derivative of heptaplatin, cis-{Pt(II)[(4S,5S)-4,5-bis(aminomethyl)-2-isopropyl-1,3-dioxolane]·(3-hydroxyl-cyclobutane-1,1-dicarboxylate)}.

    PubMed

    Liu, Weiping; Jiang, Jing; Xie, Chengying; Hou, Shuqian; Quan, Haitian; Ye, Qingsong; Lou, Liguang

    2014-11-01

    A water-soluble 4S,5S-derivative of heptaplatin, cis-{Pt(II)[(4S,5S)-4,5-bis(aminomethyl)-2-isopropyl-1,3-dioxolane]·(3-hydroxyl-cyclobutane-1,1-dicarboxylate)} was synthesized. The anticancer activity and toxicity were evaluated by comparing its interaction with DNA, cytotoxicity against four human cancer cell lines, antitumor efficiency in human gastric carcinoma NCI-N87 xenografts in nude mice, and preliminary side-effects in rats to those of its 4R,5R-optical isomer which is under preclinical development. Both isomers induce condensation of DNA to the same extent and have similar cytotoxicity, but show different antitumor activity and toxicity, probably owing to the difference in respective pharmacokinetic profiles. 4S,5S-Isomer seems to exhibit superior antitumor activity and less toxicity than 4R,5R-optical isomer as well as the parent heptaplatin. These results imply that 4S,5S-configuration as a new drug candidate may be better than 4R,5R-counterpart.