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Sample records for peroxido acido ativado

  1. Evaluations of Tumor Acidosis Within In Vivo Tumor Models Using Parametric Maps Generated with AcidoCEST MRI

    PubMed Central

    Chen, Liu Qi; Randtke, Edward A.; Jones, Kyle M.; Moon, Brianna F.; Howison, Christine M.; Pagel, Mark D.

    2016-01-01

    Purpose We aimed to develop pixelwise maps of tumor acidosis to aid in evaluating extracellular tumor pH (pHe) in cancer biology. Procedures MCF-7 and MDA-MB-231 mouse models were imaged during a longitudinal study. AcidoCEST MRI and a series of image processing methods were used to produce parametric maps of tumor pHe, and tumor pHe was also measured with a pH microsensor. Results Sufficient contrast-to-noise for producing pHe maps was achieved by using standard image processing methods. A comparison of pHe values measured with acidoCEST MRI and a pH microsensor showed that acidoCEST MRI measured tumor pHe with an accuracy of 0.034 pH units. The MCF-7 tumor model was found to be more acidic compared to the MDA-MB-231 tumor model. The pHe was not related to tumor size during the longitudinal study. Conclusions These results show that acidoCEST MRI can create pixelwise tumor pHe maps of mouse models of cancer. PMID:25622809

  2. Some Biochemical Properties of an Acido-Thermophilic Archae-Bacterium Sulfolobus Acidocaldarius

    NASA Astrophysics Data System (ADS)

    Oshima, Tairo; Ohba, Masayuki; Wagaki, Takayoshi

    1984-12-01

    To elucidate the phylogenic status of archaebacteria, some basic cellular components of an acido-thermophilic archaebacterium,Sulfolobus acidocaldarius, were studied. Poly(A) containing RNA was present in the cells, and performed the role of mRNA in a cell-free extract of reticulocyte or the archaebacteria. Poly(A) containing RNA was also found in other archaebacterial cells. The absence of cap structure was suggested in these RNAs. The cell-free protein synthesis using the archaebacterial extract was inhibited by anisomycin, a specific inhibitor for eukaryotic ribosomes. Two unique membrane-bound ATPases were detected. Based on resistance to H+-ATPase inhibitors, these enzymes seemed not to be F0F1-ATPase.

  3. Assessing Metabolic Changes in Response to mTOR Inhibition in a Mantle Cell Lymphoma Xenograft Model Using AcidoCEST MRI

    PubMed Central

    Akhenblit, Paul J.; Hanke, Neale T.; Gill, Alexander; Persky, Daniel O.; Howison, Christine M.; Pagel, Mark D.; Baker, Amanda F.

    2016-01-01

    AcidoCEST magnetic resonance imaging (MRI) has previously been shown to measure tumor extracellular pH (pHe) with excellent accuracy and precision. This study investigated the ability of acidoCEST MRI to monitor changes in tumor pHe in response to therapy. To perform this study, we used the Granta 519 human mantle cell lymphoma cell line, which is an aggressive B-cell malignancy that demonstrates activation of the phosphatidylinositol-3-kinase/Akt/mammalian target of rapamycin (mTOR) pathway. We performed in vitro and in vivo studies using the Granta 519 cell line to investigate the efficacy and associated changes induced by the mTOR inhibitor, everolimus (RAD001). AcidoCEST MRI studies showed a statistically significant increase in tumor pHe of 0.10 pH unit within 1 day of initiating treatment, which foreshadowed a decrease in tumor growth of the Granta 519 xenograft model. AcidoCEST MRI then measured a decrease in tumor pHe 7 days after initiating treatment, which foreshadowed a return to normal tumor growth rate. Therefore, this study is a strong example that acidoCEST MRI can be used to measure tumor pHe that may serve as a marker for therapeutic efficacy of anticancer therapies. PMID:27140422

  4. Assessing Metabolic Changes in Response to mTOR Inhibition in a Mantle Cell Lymphoma Xenograft Model Using AcidoCEST MRI.

    PubMed

    Akhenblit, Paul J; Hanke, Neale T; Gill, Alexander; Persky, Daniel O; Howison, Christine M; Pagel, Mark D; Baker, Amanda F

    2016-01-01

    AcidoCEST magnetic resonance imaging (MRI) has previously been shown to measure tumor extracellular pH (pHe) with excellent accuracy and precision. This study investigated the ability of acidoCEST MRI to monitor changes in tumor pHe in response to therapy. To perform this study, we used the Granta 519 human mantle cell lymphoma cell line, which is an aggressive B-cell malignancy that demonstrates activation of the phosphatidylinositol-3-kinase/Akt/mammalian target of rapamycin (mTOR) pathway. We performed in vitro and in vivo studies using the Granta 519 cell line to investigate the efficacy and associated changes induced by the mTOR inhibitor, everolimus (RAD001). AcidoCEST MRI studies showed a statistically significant increase in tumor pHe of 0.10 pH unit within 1 day of initiating treatment, which foreshadowed a decrease in tumor growth of the Granta 519 xenograft model. AcidoCEST MRI then measured a decrease in tumor pHe 7 days after initiating treatment, which foreshadowed a return to normal tumor growth rate. Therefore, this study is a strong example that acidoCEST MRI can be used to measure tumor pHe that may serve as a marker for therapeutic efficacy of anticancer therapies. PMID:27140422

  5. Respiration gating and Bloch fitting improve pH measurements with acidoCEST MRI in an ovarian orthotopic tumor model

    PubMed Central

    Jones, Kyle M; Randtke, Edward A; Howison, Christine M; Pagel, Mark D

    2016-01-01

    We have developed a MRI method that can measure extracellular pH in tumor tissues, known as acidoCEST MRI. This method relies on the detection of Chemical Exchange Saturation Transfer (CEST) of iopamidol, an FDA-approved CT contrast agent that has two CEST signals. A log10 ratio of the two CEST signals is linearly correlated with pH, but independent of agent concentration, endogenous T1 relaxation time, and B1 inhomogeneity. Therefore, detecting both CEST effects of iopamidol during in vivo studies can be used to accurately measure the extracellular pH in tumor tissues. Past in vivo studies using acidoCEST MRI have suffered from respiration artifacts in orthotopic and lung tumor models that have corrupted pH measurements. In addition, the non-linear fitting method used to analyze results is unreliable as it is subject to over-fitting especially with noisy CEST spectra. To improve the technique, we have recently developed a respiration gated CEST MRI pulse sequence that has greatly reduced motion artifacts, and we have included both a prescan and post scan to remove endogenous CEST effects. In addition, we fit the results by parameterizing the contrast of the exogenous agent with respect to pH via the Bloch equations modified for chemical exchange, which is less subject to over-fitting than the non-linear method. These advances in the acidoCEST MRI technique and analysis methods have made pH measurements more reliable, especially in areas of the body subject to respiratory motion. PMID:27212783

  6. Respiration gating and Bloch fitting improve pH measurements with acidoCEST MRI in an ovarian orthotopic tumor model

    NASA Astrophysics Data System (ADS)

    Jones, Kyle M.; Randtke, Edward A.; Howison, Christine M.; Pagel, Mark D.

    2016-03-01

    We have developed a MRI method that can measure extracellular pH in tumor tissues, known as acidoCEST MRI. This method relies on the detection of Chemical Exchange Saturation Transfer (CEST) of iopamidol, an FDA-approved CT contrast agent that has two CEST signals. A log10 ratio of the two CEST signals is linearly correlated with pH, but independent of agent concentration, endogenous T1 relaxation time, and B1 inhomogeneity. Therefore, detecting both CEST effects of iopamidol during in vivo studies can be used to accurately measure the extracellular pH in tumor tissues. Past in vivo studies using acidoCEST MRI have suffered from respiration artifacts in orthotopic and lung tumor models that have corrupted pH measurements. In addition, the non-linear fitting method used to analyze results is unreliable as it is subject to over-fitting especially with noisy CEST spectra. To improve the technique, we have recently developed a respiration gated CEST MRI pulse sequence that has greatly reduced motion artifacts, and we have included both a prescan and post scan to remove endogenous CEST effects. In addition, we fit the results by parameterizing the contrast of the exogenous agent with respect to pH via the Bloch equations modified for chemical exchange, which is less subject to over-fitting than the non-linear method. These advances in the acidoCEST MRI technique and analysis methods have made pH measurements more reliable, especially in areas of the body subject to respiratory motion.

  7. Acido-basic control of the thermoelectric properties of poly(3,4-ethylenedioxythiophene)tosylate (PEDOT-Tos) thin films

    PubMed Central

    Khan, Zia Ullah; Bubnova, Olga; Jafari, Mohammad Javad; Brooke, Robert; Liu, Xianjie; Gabrielsson, Roger; Ederth, Thomas; Evans, Drew R.; Andreasen, Jens W.; Fahlman, Mats

    2015-01-01

    PEDOT-Tos is one of the conducting polymers that displays the most promising thermoelectric properties. Until now, it has been utterly difficult to control all the synthesis parameters and the morphology governing the thermoelectric properties. To improve our understanding of this material, we study the variation in the thermoelectric properties by a simple acido-basic treatment. The emphasis of this study is to elucidate the chemical changes induced by acid (HCl) or base (NaOH) treatment in PEDOT-Tos thin films using various spectroscopic and structural techniques. We could identify changes in the nanoscale morphology due to anion exchange between tosylate and Cl– or OH–. But, we identified that changing the pH leads to a tuning of the oxidation level of the polymer, which can explain the changes in thermoelectric properties. Hence, a simple acid–base treatment allows finding the optimum for the power factor in PEDOT-Tos thin films. PMID:27019715

  8. Physiological roles of peroxido-vanadium complexes: Leitmotif as their signal transduction pathway.

    PubMed

    Matsugo, Seiichi; Kanamori, Kan; Sugiyama, Hironori; Misu, Hirofumi; Takamura, Toshinari

    2015-06-01

    Evidence exists that supports the various physiological roles of vanadium compounds, although the amount of vanadium in our body is limited. This limited concentration in our body does not attract much attention of the biological chemists, although the fact is present; even in the 19th century, vanadium derivatives were used for the therapeutic reagents. In the middle of the 20th century, the main focus of vanadium chemistry is mainly on the chemical and material fields. After the first discovery of vanadium compounds expressing ATPase activity, oxidovanadium(IV) sulfate was reported to have insulin mimic activity. Additionally, because some vanadium compounds possess cellular toxicity, trials were also carried out to examine the possible use of vanadium compounds as cancer therapeutics. The application of vanadium complexes was extended in recent years especially in the 21st century. In this review, we briefly explain the historical background of vanadium chemistry and also summarize the physiological role of vanadium complexes mainly focusing on the synthesis and physiological role of peroxidovanadium compounds and their interactions with insulin signal transduction pathways. PMID:25912243

  9. μ-η2:η2-Peroxido-bis­[nitratodioxido­bis(pyrrolidin-2-one)uranium(VI)

    PubMed Central

    Takao, Koichiro; Ikeda, Yasuhisa

    2010-01-01

    In the crystal structure of the title compound, [U2(NO3)2O4(O2)(C4H7NO)4], two UO2 2+ ions are connected by a μ-η2:η2-O2 unit. The O2 unit shows ‘side-on’ coordination to both U atoms. An inversion center is located at the midpoint of the O—O bond in the O2 unit, affording a centrosymmetrically expanded dimeric structure. The U—O(axial) bond lengths are 1.777 (4) Å and 1.784 (4) Å, indicating that the oxidation state of U is exclusively 6+, i.e., UO2 2+. Furthermore, the O—O distance is 1.492 (8) Å, which is typical of peroxide, O2 2–. The U atom is eight-coordinated in a hexa­gonal-bipyramidal geometry. The coordinating atoms of the nitrate and pyrrolidine-2-one ligands and the μ-η2:η2-O2 2– unit are located in the equatorial plane and form an irregular hexa­gon. An inter­molecular hydrogen bond is found between N—H of the pyrrolidine-2-one ligand and the coordinating O of the same ligand in a neighboring complex. A second inter­molecular hydrogen bond is found between the N—H of the other pyrrolidine-2-one ligand and one of the uranyl oxido atoms. PMID:21579030

  10. Acido-basic properties of proton pump inhibitors in aqueous solutions.

    PubMed

    Kristl, Albin

    2009-01-01

    The pharmacological characteristics of proton pump inhibitors are related to their protolytic behavior estimated by their pK(a) values. Lansoprazole is a potent anti-acid drug from this group. Because of its poor stability a rapid spectrophotometric method was developed for the determination of its pK(a) values. Three pK(a) values were obtained: an acidic pK(a1) = 8.84 and two basic, pK(a2) = 4.15 and pK(a3) = 1.33. These pK(a) values were discussed from the point of lansoprazole structure and instability with the aim of locating basic and acidic moieties in the molecule of proton pump inhibitors. They were also compared with experimentally determined pK(a) values from the literature and with some pK(a) values calculated by different programs. PMID:18720145

  11. Sorption of uranyl ions from various acido systems by amphoteric epoxy amine ion-exchange resins

    SciTech Connect

    Rychkov, V.N.; Radionov, B.K.; Molochnikov, L.S.

    1995-03-01

    Sorption of uranyl ions by epoxy amine ampholytes with N-monomethylenephosphonic acid groups modified with pyridine or quaternary ammonium groups was studied under dynamic conditions. Heterocyclic nitrogen favors sorption of uranyl ion from fluoride, sulfate, and fluoride-sulfate solutions. The ESR studies of mono- and bimetallic forms of nitrogen-containing ampholytes with copper(II) as paramagnetic marker revealed the characteristics of uranium(VI) interaction with cation- and anion-exchange groups and its dependence on the fluoride content in solution.

  12. Acido, ergo sum: Holger Hydén--the neuroscientist in Cortázar's Hopscotch.

    PubMed

    Delgado, Guillermo; Estañol, Bruno

    2013-06-01

    The fictional Italian author Morelli is throughout the novel "Hopscotch" (1963) Julio Cortázar's alter ego. This character proposes an unoriginal literary hypothesis in chapter 62. There is an allusion to a particular Swedish that 'is working on a chemical theory of thought.' The Swedish neuroscientist under analysis is Holger Hydén (1917-2000), by then professor and chairman of the Department of Histology at the University of Göteborg. Hydén, who was the first to work in neurobiological micromethods, is mentioned by Morelli due to his participation in a symposium held at the end of January 1961, in San Francisco. His pioneering work will never be completely forgotten, because Hydén's neuroscientific legacy lives and will live in Cortázar's "Hopscotch". PMID:23828537

  13. Tris(1,10-phenanthroline-κ2 N,N′)nickel(II) hexa­oxido-μ-peroxido-disulfate­(VI) N,N-dimethyl­formamide disolvate monohydrate

    PubMed Central

    Harvey, Miguel Angel; Suarez, Sebastián; Doctorovich, Fabio; Baggio, Ricardo

    2013-01-01

    The asymmetric unit of the title complex, [Ni(C12H8N2)3]S2O8·2C3H7NO·H2O, consists of a complex [Ni(phen)3]2+ cation and one isolated pds anion, with two DMF mol­ecules and one water mol­ecule as solvates (where phen is 1,10-phenanthroline, pds is the hexa­oxido-μ-peroxoido-di­sulf­ate dianion and DMF is dimethyl­formamide). The [Ni(phen)3]2+ cation is regular, with an almost ideal NiII bond-valence sum of 2.07 v.u. The group, as well as the water solvent mol­ecule, are well behaved in terms of crystallographic order, but the remaining three mol­ecules in the structure display different kinds of disorder, viz. the two DMF mol­ecules mimic a twofold splitting and the pds anion has both S atoms clamped at well-determined positions but with a not-too-well-defined central part. These peculiar behaviours are a consequence of the hydrogen-bonding inter­actions: the outermost SO3 parts of the pds anion are heavily connected to the complex cations via C—H⋯O hydrogen bonding, generating an [Ni(phen)3]pds network and providing for the stability of the terminal pds sites. Also, the water solvent mol­ecule is strongly bound to the structure (being a donor of two strong bonds and an acceptor of one) and is accordingly perfectly ordered. The peroxide O atoms in the pds middle region, instead, appear as much less restrained into their sites, which may explain their tendency to disorder. The cation–anion network leaves large embedded holes, amounting to about 28% of the total crystal volume, which are occupied by the DMF mol­ecules. The latter are weakly inter­acting with the rest of the structure, which renders them much more labile and, accordingly, prone to disorder. PMID:23476355

  14. Effects of acido-basic support properties on the catalytic hydrogenation of acetylene on gold nano-particles

    NASA Astrophysics Data System (ADS)

    Manda, Abdullah Ahmed

    Metallic gold nanoparticles supported on gamma-Al2O 3 and magnesia-alumina mixed oxide, with different magnesia content have been prepared by sol-gel method and characterized by different techniques (inductive coupled plasma-mass spectroscopy (ICP-MS), XRD, BET surface area analysis, transmission electron microscopy (TEM), CO2 and NH 3 temperature programmed desorption (TPD), H2 temperature programmed reduction (TPR) and FTIR of adsorbed CO2). Such systems were found to produce catalysts with controllable acidity, varying from catalyst possessing large density of acidic and low density of basic sites, others with acidic and basic sites of equal strength and density, and others with large basic and low acid sites densities, respectively. The catalytic assessment of the generated acidity was carried out using 2-propanol decomposition as a test reaction. The results obtained indicate that the presence of magnesia and reduced gold nanopartilces has imparted the catalysts, 1%Au/4%Mg-Al 2O3 and 1%Au/8%Mg-Al2O3, with significant base-catalytic properties. Acetylene hydrogenation and formation of coke deposits were investigated on a gold catalyst supported on gamma-Al2O3 and gold supported on alumina-magnisia mixed oxide with different gold content; 1%Au/gamma-Al 2O3, 1%Au/15%Mg-Al2O3, 2%Au/15%Mg-Al 2O3 and 4%Au/15%Mg-Al2O3. The effect of the H2/C2H2 ratio was studied over a range of values. The catalytic activity and selectivity towards ethylene and other products were investigated at different reaction temperatures. Acetylene hydrogenation was investigated in the presence and absence of ethylene in stream. It is investigated that the adsorption of the triple bond is preferred over the double bond and during selective catalytic (SCR) of C2H2 the two hydrocarbons do not compete for the same adsorption sites. The deactivation of catalysts was studied by temperature programmed oxidation (TPO). Higher content of coke over 1%Au/Al2O3 catalyst was investigated in contrast to the other catalysts in which the basisity of magnesia-alumina supports could have played an important role in inhibiting the acidic carbon formation by possessing smaller number and/or weaker acid sites.

  15. Crystal Structure of ATVORF273, a New Fold for a Thermo- and Acido-Stable Protein from the Acidianus Two-Tailed Virus

    PubMed Central

    Felisberto-Rodrigues, Catarina; Blangy, Stéphanie; Goulet, Adeline; Vestergaard, Gisle; Cambillau, Christian; Garrett, Roger A.; Ortiz-Lombardía, Miguel

    2012-01-01

    Acidianus two-tailed virus (ATV) infects crenarchaea of the genus Acidianus living in terrestrial thermal springs at extremely high temperatures and low pH. ATV is a member of the Bicaudaviridae virus family and undergoes extra-cellular development of two tails, a process that is unique in the viral world. To understand this intriguing phenomenon, we have undertaken structural studies of ATV virion proteins and here we present the crystal structure of one of these proteins, ATV. ATV forms tetramers in solution and a molecular envelope is provided for the tetramer, computed from small-angle X-ray scattering (SAXS) data. The crystal structure has properties typical of hyperthermostable proteins, including a relatively high number of salt bridges. However, the protein also exhibits flexible loops and surface pockets. Remarkably, ATV displays a new protein fold, consistent with the absence of homologues of this protein in public sequence databases. PMID:23056221

  16. Effectiveness of anisodamine for the treatment of critically ill patients with septic shock (ACIdoSIS study): study protocol for randomized controlled trial

    PubMed Central

    Zhou, Jiancang; Shang, You; Wang, Xin’an; Yin, Rui; Zhu, Zhenhua; Chen, Wensen; Tian, Xin; Yu, Yuetian; Zuo, Xiangrong; Chen, Kun; Ji, Xuqing; Ni, Hongying

    2015-01-01

    Background Septic shock is an important contributor of mortality in the intensive care unit (ICU). Although strenuous effort has been made to improve its outcome, the mortality rate is only marginally decreased. The present study aimed to investigate the effectiveness of anisodamine in the treatment of septic shock, in the hope that the drug will provide alternatives to the treatment of septic shock. Methods The study is a multi-center randomized controlled clinical trial. Study population will include critically ill patients with septic shock requiring vasopressor use. Blocked randomization was performed where anisodamine and control treatments were allocated at random in a ratio of 1:1 in blocks of sizes 2, 4, 6, 8, and 10 to 354 subjects. Interim analysis will be performed. The primary study end point is the hospital mortality, and other secondary study endpoints include ICU mortality, length of stay in ICU and hospital, organ failure free days. Adverse events including new onset psychosis, urinary retention, significant hypotension and tachycardia will be reported. Discussion The study will provide new insight into the treatment of septic shock and can help to reduce mortality rate of septic shock. Trial registration NCT02442440 (https://register.clinicaltrials.gov/). PMID:26605292

  17. Crystal structure of μ-peroxido-κ4 O 1,O 2:O 1′,O 2′-bis­[(nitrato-κO)(2,2′:6′,2′′-terpyridine-κ3 N,N′,N′′)dioxidouranium(VI)

    PubMed Central

    Kawasaki, Takeshi; Kitazawa, Takafumi

    2015-01-01

    In the title dimeric complex, [{UO2(NO3)(C15H11N3)}2O2], a peroxide ion bridges the two uran­yl(VI) [O=U=O]2+ ions. The O—O bond length of the peroxide is 1.485 (6) Å and the mid-point of this bond is located at the inversion centre of the dimer. The U atom exhibits a distorted hexa­gonal–bipyramidal coordination geometry with two uran­yl(VI) O atoms occupying the axial positions and one O atom of the monodentate nitrate ion, both O atoms of the peroxide ion and the three N atoms of the chelating tridentate 2,2′:6′,2′′-terpyridine (terpy) ligand in the equatorial positions. Two of the N atoms of the terpy ligand lie above and below the mean plane containing the equatorial ligand atoms and the U atom [deviations from the mean plane: maximum 0.500 (2), minimum −0.472 (2) and r.m.s. = 0.2910 Å]. The dihedral angle between the terpy ligand and the mean plane is 35.61 (7)°. The bond lengths around the U atom decrease in the order U—N > U—Onitrate > U—Operoxo > U=O. The dimeric complexes pack in a three-dimensional network held together by weak π–π inter­actions [centroid–centroid distance = 3.659 (3) Å] between pyridyl rings of the terpy ligands in neighbouring dimers, together with inter­molecular C—H⋯O and C—H⋯π inter­actions. Weak intra­molecular C—H⋯O inter­actions are also observed. PMID:25995895

  18. Archaebakterien und Phylogenie der Organismen

    NASA Astrophysics Data System (ADS)

    Kandler, Otto

    1981-04-01

    The determination of the sequence similarity of the ribosomal 16 S RNA of many bacteria and a few higher organisms has shown that the methanogenic, halophilic, and acido-thermophilic organisms are phylogenetically separated from the kingdoms of the Eubacteria and Eukaryotes thus representing a third kingdom called “Archaebacteria”. Many biochemical and molecular biological features support this conclusion.

  19. Inhibition of fructan-fermenting equine fecal bacteria and Streptococcus bovis by hops (Humulus lupulus L.) ß-acid

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aims: The goals were to determine if the '-acid from hops (Humulus lupulus L.) could be used to control fructan fermentation by equine hindgut microorganisms, and to verify the antimicrobial mode of action on the Streptococcus bovis, which has been implicated in fructan fermentation, hindgut acidos...

  20. Amino alcohol-derived reduced Schiff base V(IV)O and V(V) compounds as catalysts for asymmetric sulfoxidation of thioanisole with hydrogen peroxide.

    PubMed

    Adão, Pedro; Kuznetsov, Maxim L; Barroso, Sónia; Martins, Ana M; Avecilla, F; Costa Pessoa, João

    2012-11-01

    We report the synthesis and characterization of several amino alcohol-derived reduced Schiff base ligands (AORSB) and the corresponding V(IV)O and V(V) complexes. Some of the related Schiff base variants (amino alcohol derived Schiff base = AOSB) were also prepared and characterized. With some exceptions, all compounds are formulated as dinuclear compounds {V(IV)O(L)}(2) in the solid state. Suitable crystals for X-ray diffraction were obtained for two of the AORSB compounds, as well as a rare X-ray structure of a chiral V(IV)O compound, which revealed a dinuclear {V(IV)O(AOSB)}(2) structure with a rather short V-V distance of 3.053(9) Å. Electron paramagnetic resonance (EPR), (51)V NMR, and density functional theory (DFT) studies were carried out to identify the intervenient species prior to and during catalytic reactions. The quantum-chemical DFT calculations were important to determine the more stable isomers in solution, to explain the EPR data, and to assign the (51)V NMR chemical shifts. The V(AORSB) and V(AOSB) complexes were tested as catalysts in the oxidation of thioanisole, with H(2)O(2) as the oxidant in organic solvents. In general, high conversions of sulfoxide were obtained. The V(AOSB) systems exhibited greater activity and enantioselectivity than their V(AORSB) counterparts. Computational and spectroscopic studies were carried out to assist in the understanding of the mechanistic aspects and the reasons behind such marked differences in activity and enantioselectivity. The quantum-chemical calculations are consistent with experimental data in the assessment of the differences in catalytic activity between V(AOSB) and V(AORSB) peroxido variants because the V(AORSB) peroxido transition states correspond to ca. 22 kJ/mol higher energy activation barriers than their V(AOSB) counterparts. PMID:23092396

  1. Lewis acid tuned facial stereodivergent HDA reactions using beta-substituted N-vinyloxazolidinones.

    PubMed

    Gohier, Frédéric; Bouhadjera, Keltoum; Faye, Djibril; Gaulon, Catherine; Maisonneuve, Vincent; Dujardin, Gilles; Dhal, Robert

    2007-01-18

    The [4 + 2] acido-catalyzed heterocycloaddition between new beta-substituted N-vinyl-1,3-oxazolidin-2-ones (with R' = Me, Ar, CH2 Ar) and beta,gamma-unsaturated alpha-ketoesters (R = Ar) afforded heteroadducts with high levels of endo and facial selectivities. A complete reversal of facial differentiation was achieved by varying the Lewis acid, leading to the stereoselective formation of either endo-alpha or endo-beta adducts. [reaction: see text]. PMID:17217267

  2. Comparative Studies on Biochemical Properties of Protein Synthesis of an Archae-Bacteria Thermoplasma-Sp

    NASA Astrophysics Data System (ADS)

    Ohba, Masayuki; Oshima, Tairo

    1982-12-01

    An acido-thermophillic archaebacteria,Thermoplasma strain KO-2, produced poly(A) containing RNA. The isolated poly(A)RNA showed the messenger activity in a cell-free extract of rabbit reticulocyte, indicating that the RNA is mRNA of the archaebacteria. 7-Methylgluanosine 5'-phosphate did not inhibit the reaction, suggesting that the cap structure is not present in the messenger. These results may suggest that poly(A) containing messenger arised at very early stage of evolution prior to the divergence between archaebacteria and eukaryotes.

  3. [Childhood memories…].

    PubMed

    Uguen, Arnaud; Schoenlaub, Patricia; Abalain, Marie-Louise; Grippari, Jean-Luc

    2012-06-01

    Leprosy is still a largely worldwide spread disease but rarely encountered in metropolitan France. Its identification implies a multidisciplinary clinical, pathological and bacteriological diagnosis which is necessary to an efficient antibiotic treatment against a crippling disease which remains curable. Here we report the case of a 24-year-old man who was showing an original both cutaneous and pulmonary presence of acido-alcooloresistant bacillus which have been identified as Mycobacterium leprae by polymerase chain reaction (PCR). This unusual presentation of a cutaneous and pulmonary leprosy raises the problem of its differential diagnoses, including those of non-tuberculosis mycobacterial infections. PMID:22748342

  4. FT-IR characterization of the acidic and basic sites on a nanostructured aluminum nitride surface

    SciTech Connect

    Baraton, M.I.; Chen, X.; Gonsalves, K.E.

    1997-12-31

    A nanostructured aluminum nitride powder prepared by sol-gel type chemical synthesis is analyzed by Fourier transform infrared spectrometry. The surface acidic and basic sites are probed out by adsorption of several organic molecules. Resulting from the unavoidable presence of oxygen, the aluminum nitride surface is an oxinitride layer in fact, and its surface chemistry should present some analogies with alumina. Therefore, a thorough comparison between the acido-basicity of aluminum nitride and aluminum oxide is discussed. The remaining nitrogen atoms in the first atomic layer modify the acidity-basicity relative balance and reveals the specificity of the aluminum nitride surface.

  5. First principle study of the surface reactivity of layered lithium oxides LiMO2 (M = Ni, Mn, Co)

    NASA Astrophysics Data System (ADS)

    Vallverdu, Germain; Minvielle, Marie; Andreu, Nathalie; Gonbeau, Danielle; Baraille, Isabelle

    2016-07-01

    LiNixMnyCo1 - x - yO2 compounds (NMC) are layered oxides widely used in commercial lithium-ion batteries at the positive electrode. Nevertheless surface reactivity of this material is still not well known. As a first step, based on first principle calculations, this study deals with the electronic properties and the surface reactivity of LiMO2 (M = Co, Ni, Mn) compounds, considering the behavior of each transition metal separately in the same R 3 ̅ mα-NaFeO2-type structure, the one of LiCoO2 and NMC. For each compound, after a brief description of the bare slab electronic properties, we explored the acido-basic and redox properties of the (110) and (104) surfaces by considering the adsorption of a gaseous probe. The chemisorption of SO2 produces both sulfite or sulfate species associated respectively to an acido-basic or a reduction process. These processes are localized on the transition metals of the first two layers of the surface. Although sulfate species are globally favored, a different behavior is obtained depending on both the surface and the transition metal considered. We conclude with a simple scheme which describes the reduction processes on the both surfaces in terms of formal oxidation degrees of transition metals.

  6. [Age and the course of nephrotoxic nephritis in rats].

    PubMed

    Samoĭlova, Z T; Kliukina, S S

    1978-12-01

    In experiments on two groups of mongrel rats (4 weeks old and 4 months old) with induced nephrotoxic nephritis it was revealed that in comparison with adult rats the course of nephritis in ratlings was characterized by lesser proteinuria, selective in nature, by lesser reducticn of endogenous creatinine clearance and diuresis. The acido- and ammo-niogenesis decreased in ratlings and adult rats to the same extent. Morphological changes in the kidneys of ratlings were less pronounced than in adult animals, and were mostly localized in the convoluted tubules. The level of DNA-synthetic activity of the epithelial nuclei of the glomeruli prevailed over this index of the convoluted tubules epithelium. The weight index of the kidneys increased less in ratlings with nephritis than in adult rats. beta-lipoproteinemia in ratlings increased 8 times. Normalization of the urine and blood indices occurred more rapidly in ratlings than in adult rats. PMID:31956

  7. Tuberculose pulmonaire révélée par un purpura thrombopénique chez l'enfant-à propos d'un cas clinique observé au service de pédiatrie des Cliniques Universitaires de Lubumbashi

    PubMed Central

    Lubala, Toni Kasole; Mutombo, Augustin Mulangu; Munkana, Arthur Ndundula; Manika, Michel Muteya

    2012-01-01

    Nous rapportons le cas d'un enfant de 7 ans, de sexe masculin ayant présenté un purpura thrombopénique avec épistaxis, hématémèse, otorragies et pétéchies généralisées. Durant la même hospitalisation, nous avons mis en évidence une tuberculose pulmonaire documentée par la présence de bacilles acido-alcoolo résistants à l'examen des crachats. Nous avons observé une majoration du taux de plaquettes en une semaine de corticothérapie intraveineuse à haute dose, avant l'instauration d'une poly chimiothérapie antituberculeuse. Nous rappelons également la controverse que suscite la prise en charge de cette association rarement rapportée. PMID:23077696

  8. Binding of oxime group to uranyl ion.

    PubMed

    Tsantis, Sokratis T; Zagoraiou, Eirini; Savvidou, Aikaterini; Raptopoulou, Catherine P; Psycharis, Vassilis; Szyrwiel, Lukasz; Hołyńska, Małgorzata; Perlepes, Spyros P

    2016-05-31

    Currently, the leading approach for extraction of uranium from seawater is selective sorption of UO2(2+) ions onto a poly(acrylamidoxime) fiber. Amidoxime functional groups are the most studied extractant moieties for this application, but are not perfectly selective, and understanding how these groups (and more generally the oxime groups) interact with UO2(2+) and competing ions in seawater is an important step in designing better extractants. We have started a new research programme aiming at in-depth studies of the uranyl-oxime/amidoxime interactions and we report here our first results which cover aspects of the coordination chemistry of 2-pyridyl ketoximes towards UO2(2+). Detailed synthetic investigations of various UO2(2+)/mepaoH and UO2(2+)/phpaoH reaction systems (mepaoH is methyl 2-pyridyl ketoxime and phpaoH is phenyl 2-pyridyl ketoxime) have provided access to the complexes [UO2(mepao)2(MeOH)2]{[UO2(NO3)(mepao)(MeOH)2]}2 (), [UO2(mepao)2(MeOH)2] (), [(UO2)2(O2)(O2CMe)2(mepaoH)2] () and [UO2(phpao)2(MeOH)2] (). The peroxido group in , which was isolated without the addition of external peroxide sources, probably arises from a bis(aquo)- and/or bis(hydroxido)-bridged diuranyl precursor in solution followed by photochemical oxidation of the bridging groups. The U(VI) atom in the [UO2(NO3)(mepao)(MeOH)2] molecules of () is surrounded by one nitrogen and seven oxygen atoms in a very distorted hexagonal bipyramidal geometry; two oxygen atoms from the terminal MeOH ligands, two oxygen atoms from the bidentate chelating nitrato group, and the oxygen and nitrogen atoms from the η(2) oximate group of the 1.110 (Harris notation) mepao(-) ligand define the equatorial plane. This plane consists of two terminal MeOH ligands and two η(2) oximate groups in the [UO2(mepao)2(MeOH)2] molecule () of . The structure of the [UO2(mepao)2(MeOH)2] molecule that is present in is very similar to the structure of the corresponding molecule in . The structure of the dinuclear

  9. Adsorption mechanism of acids and bases in reversed-phase liquid chromatography in weak buffered mobile phases designed for liquid chromatography/mass spectrometry

    SciTech Connect

    Gritti, Fabrice; Guiochon, Georges A

    2009-01-01

    The overloaded band profiles of five acido-basic compounds were measured, using weakly buffered mobile phases. Low buffer concentrations were selected to provide a better understanding of the band profiles recorded in LC/MS analyses, which are often carried out at low buffer concentrations. In this work, 10 {micro}L samples of a 50 mM probe solution were injected into C{sub 18}-bonded columns using a series of five buffered mobile phases at {sub W}{sup S}pH between 2 and 12. The retention times and the shapes of the bands were analyzed based on thermodynamic arguments. A new adsorption model that takes into account the simultaneous adsorption of the acidic and the basic species onto the endcapped adsorbent, predicts accurately the complex experimental profiles recorded. The adsorption mechanism of acido-basic compounds onto RPLC phases seems to be consistent with the following microscopic model. No matter whether the acid or the base is the neutral or the basic species, the neutral species adsorbs onto a large number of weak adsorption sites (their saturation capacity is several tens g/L and their equilibrium constant of the order of 0.1 L/g). In contrast, the ionic species adsorbs strongly onto fewer active sites (their saturation capacity is about 1 g/L and their equilibrium constant of the order of a few L/g). From a microscopic point of view and in agreement with the adsorption isotherm of the compound measured by frontal analysis (FA) and with the results of Monte-Carlo calculations performed by Schure et al., the first type of adsorption sites are most likely located in between C{sub 18}-bonded chains and the second type of adsorption sites are located deeper in contact with the silica surface. The injected concentration (50 mM) was too low to probe the weakest adsorption sites (saturation capacity of a few hundreds g/L with an equilibrium constant of one hundredth of L/g) that are located at the very interface between the C{sub 18}-bonded layer and the bulk

  10. Structures of nitrato-(2-hydroxybenzaldehydo) (2,2 Prime -bipyridyl)copper and nitrato-(2-hydroxy-5-nitrobenzaldehydo)(2,2 Prime -bipyridyl)copper

    SciTech Connect

    Chumakov, Yu. M.; Paladi, L. G.; Antosyak, B. Ya.; Simonov, Yu. A.; Tsapkov, V. I.; Bocelli, G.; Gulea, A. P.; Ginju, D.; Palomares-Sanchez, S. A.

    2011-03-15

    Nitrato-(2-hydroxy-5-nitrobenzaldehydo)(2,2 Prime -bipyridyl)copper (I) and nitrato-(2-hydroxybenzaldehydo)(2,2 Prime -bipyridyl)copper (II) were synthesized and characterized by X-ray diffraction. The coordination polyhedron of the central copper atom in complex I can be described as a distorted tetragonal pyramid whose base is formed by the phenol and carbonyl oxygen atoms of the monodeprotonated 2-hydroxy-5nitrobenzaldehyde molecule and the nitrogen atoms of the 2,2 Prime -bipyridyl ligand and whose apex is occupied by the oxygen atom of the nitrato group. In the crystal structure, complexes I are linked by the acido ligands and the NO{sub 2} groups of the aldehyde molecule into infinite chains. In complex II, the central copper atom is coordinated by 2-hydroxybenzaldehyde, 2,2 Prime -bipyridyl, and the nitrato group, resulting in the formation of centrosymmetric dimers. The coordination polyhedron of the central copper atom can be described as a bipyramid (4 + 1 + 1) with the same base as in complex I. The axial vertices of the bipyramid are occupied by the oxygen atom of the nitrato group and the bridging phenol oxygen atom of the adjacent complex related to the initial complex by a center of symmetry. In the crystal structure, complexes II are hydrogen bonded into infinite chains.

  11. An environmentally friendly method to remove and utilize the highly toxic strychnine in other products based on proton-transfer complexation

    NASA Astrophysics Data System (ADS)

    Adam, Abdel Majid A.; Refat, Moamen S.; Saad, Hosam A.; Hegab, Mohamed S.

    2015-12-01

    The study of toxic and carcinogenic substances represents one of the most demanding areas in human safety, due to their repercussions for public health. There is great motivation to remove and utilize these substances in other products instead of leaving them contaminate the environment. One potentially toxic compound for humans is strychnine (Sy). In the present study, we attempted to establish a quick, simple, direct and efficient method to remove and utilize discarded Sy in other products based on proton-transfer complexation. First, Sy was reacted with the acido organic acceptors PA, DNBA and CLA. Then, the resultant salts were direct carbonized into carbon materials. Also, this study provides an insight into the structure and morphology of the obtained products by a range of physicochemical techniques, such as UV-visible, IR, 1H NMR and 13C NMR spectroscopies; XRD; SEM; TEM; and elemental and thermal analyses. Interestingly, the complexation of Sy with the PA or DNBA acceptor leads to a porous carbon material, while its complexation with CLA acceptor forms non-porous carbon product.

  12. Development of a screening method for the analysis of organic pollutants in water using dual stir bar sorptive extraction-thermal desorption-gas chromatography-mass spectrometry.

    PubMed

    Tölgyessy, Peter; Vrana, Branislav; Krascsenits, Zoltán

    2011-12-15

    The development of a method for screening of organic compounds with a wide range of physico-chemical properties in water, based on dual stir bar sorptive extraction coupled with thermal desorption and gas chromatography-mass spectrometry (dual SBSE-TD-GC-MS) is described. The investigated water sample is divided into two aliquots and extracted with stir bar sorptive extraction at two different conditions: using addition of methanol or sodium chloride, respectively. Following extraction, the two stir bars are inserted into the same glass thermal desorption liner and are simultaneously desorbed and analysed by GC-MS. The method optimisation was performed using 45 environmentally harmful substances with different volatilities (boiling point from 193 to 495°C), polarity (logK(ow) from 2.17 to 8.54) and acido-basic properties. The majority of model compounds was selected from the EU list of priority substances in the field of water policy and from the US EPA method 625, respectively. Optimisation was performed for extraction parameters (sample volume, extraction time, stirring rate, addition of modifiers) as well as for the thermal desorption conditions (desorption flow, desorption time, cryofocusing temperature). Performance characteristics (recovery, repeatability, carryover, linearity, limits of detection and quantification) were determined for the optimised method. An example of analysis of a contaminated groundwater sample is presented. PMID:22099662

  13. Molluscicidal activity of various solvent extracts from Solanum nigrum var. villosum L. aerial parts against Galba truncatula

    PubMed Central

    Hammami, H.; Mezghani-Jarraya, R.; Damak, M.; Ayadi, A.

    2011-01-01

    Molluscicidal activity of Solanum nigrum var. villosum (morelle velue) extracts and their fractions were tested against the mollusca gastropoda Galba truncatula intermediate host of Fasciola hepatica. The results indicated that the hydro-methanol (MeOH-H2O) immature fruit extract possess the highest molluscicidal activity (LC50 = 3.96 mg/L) against Galba truncatula compared with other tested compounds. After acido-basic treatment, the methanolic extract fraction isolated from the immature fruits and the richest in alkaloids was the most toxic (LC50 = 1.65 mg/L). The fractions richest in saponosides obtained from the hydromethanolic and methanolic extracts of immature fruits showed interesting molluscicidal activities (LC50 = 6.15 mg/L and LC50 = 7.91 mg/L, respectively). The observed molluscicide activity could be attributed to the presence of alkaloids or saponosides. So, the immature fruits of Solanum nigrum var. villosum could be substrates of choice for molluscicide activity. In addition, total alkaloids and saponosides present in this plant deserve further investigations in order to identify the active principles and demonstrate their activities on mollusks in their natural habitat. According to the World Health Organization’s guidelines on screening for plant molluscicides, use of these fractions may add to the arsenal of methods to control snail transmitting fasciolosis in tropical and Third World countries where fasciolosis is a common disease. PMID:21395207

  14. Self-powered biosensor for ascorbic acid with a Prussian blue electrochromic display.

    PubMed

    Zloczewska, Adrianna; Celebanska, Anna; Szot, Katarzyna; Tomaszewska, Dorota; Opallo, Marcin; Jönsson-Niedziolka, Martin

    2014-04-15

    We report on the development of a nanocarbon based anode for sensing of ascorbic acid (AA). The oxidation of AA on this anode occurs at a quite low overpotential which enables the anode to be connected to a biocathode to form an ascorbic acid/O2 biofuel cell that functions as a self-powered biosensor. In conjunction with a Prussian blue electrochromic display the anode can also work as a truly self-powered sensor. The oxidation of ascorbic acid at the anode leads to a reduction of the Prussian blue in the display. The reduced form of Prussian blue, called Prussian white, is transparent. The rate of change from blue to colourless is dependent on the concentration of ascorbic acid. The display can easily be regenerated by connecting it to the biocathode which returns the Prussian blue to its oxidized form. In this way we have created the first self-powered electrochromic sensor that gives quantitative information about the analyte concentration. This is demonstrated by measuring the concentration of ascorbic acid in orange juice. The reported quantitative read-out electrochromic display can serve as a template for the creation of cheap, miniturizable sensors for other relevant analytes. PMID:24321882

  15. Assessment of carbonic anhydrase IX expression and extracellular pH in B-cell lymphoma cell line models

    PubMed Central

    Chen, Liu Qi; Howison, Christine M.; Spier, Catherine; Stopeck, Alison T.; Malm, Scott W.; Pagel, Mark D.; Baker, Amanda F.

    2015-01-01

    The expression of carbonic anhydrase (CA IX) and it’s relation to acidosis in lymphomas has not been widely studied. We investigated the protein expression of CA IX in a human B-cell lymphoma tissue microarray, and in Raji, Ramos, and Granta 519 lymphoma cell lines and tumor models, while also investigating the relation with hypoxia. An imaging method, acidoCEST MRI, was used to estimate lymphoma xenograft extracellular pH (pHe). Our results showed that clinical lymphoma tissues and cell line models in vitro and in vivo had moderate CA IX expression. Although in vitro studies showed that CA IX expression was induced by hypoxia, in vivo studies did not show this correlation. Untreated lymphoma xenograft tumor pHe had acidic fractions, and an Acidity Score was qualitatively correlated with CA IX expression. Therefore, CA IX is expressed in B-cell lymphomas and is qualitatively correlated with extracellular acidosis in xenograft tumor models. PMID:25130478

  16. Oxidative deamination by hydrogen peroxide in the presence of metals.

    PubMed

    Akagawa, Mitsugu; Suyama, Kyozo

    2002-01-01

    Various amines, including lysine residue of bovine serum albumin, were oxidatively deaminated to form the corresponding aldehydes by a H2O2/Cu2+ oxidation system at physiological pH and temperature. The resulting aldehydes were measured by high-performance liquid chromatography. We investigated the effects of metal ions, pH, inhibitors, and O2 on the oxidative deamination of benzylamine by H202. The formation of benzaldehyde was the greatest with Cu2+, and catalysis occurred with Co2+, VO2+, and Fe3+. The reaction was greatly accelerated as the pH value rose and was markedly inhibited by EDTA and catalase. Dimethyl sulfoxide and thiourea, which are hydroxyl radical scavengers, were also effective in inhibiting the generation of benzaldehyde, indicating that the reaction is a hydroxyl radical-mediated reaction. Superoxide dismutase greatly stimulated the reaction, probably due to the formation of hydroxyl radicals. O2 was not required in the oxidation, and instead slightly inhibited the reaction. We also examined several oxidation systems. Ascorbic acid/O2/Cu2+ and hemoglobin/H2O2 systems also converted benzylamine to benzaldehyde. The proposed mechanism of the oxidative deamination by H2O2/Cu2+ system is discussed. PMID:11999699

  17. Sulfoquinovose synthase – an important enzyme in the N-glycosylation pathway of Sulfolobus acidocaldarius

    PubMed Central

    Meyer, Benjamin H.; Zolghadr, Behnam; Peyfoon, Elham; Pabst, Martin; Panico, Maria; Morris, Howard R.; Haslam, Stuart M.; Messner, Paul; Schäffer, Christina; Dell, Anne; Albers, Sonja-Verena

    2015-01-01

    Summary Recently, the Surface (S)-layer glycoprotein of the thermoacidophilic crenarchaeote Sulfolobus acido-caldarius was found to be N-glycosylated with a heterogeneous family of glycans, with the largest having a composition Glc1Man2GlcNAc2 plus 6-sulfoquinovose. However, genetic analyses of genes involved in the N-glycosylation process in Crenarchaeota were missing so far. In this study we identify a gene cluster involved in the biosynthesis of sulfoquinovose and important for the assembly of the S-layer N-glycans. A successful markerless in-frame deletion of agl3 resulted in a decreased molecular mass of the S-layer glycoprotein SlaA and the flagellin FlaB, indicating a change in the N-glycan composition. Analyses with nanoLC ES-MS/MS confirmed the presence of only a reduced trisaccharide structure composed of Man1GlcNAc2, missing the sulfoquinovose, a mannose and glucose. Biochemical studies of the recombinant Agl3 confirmed the proposed function as a UDP-sulfoquinovose synthase. Furthermore, S. acidocaldarius cells lacking agl3 had a significantly lower growth rate at elevated salt concentrations compared with the background strain, underlining the importance of the N-glycosylation to maintain an intact and stable cell envelope, to enable the survival of S. acidocaldarius in its extreme environment. PMID:22059775

  18. The effect of pH on the synthesis of stable Cu2O/CuO nanoparticles by sol-gel method in a glycolic medium

    NASA Astrophysics Data System (ADS)

    Zayyoun, N.; Bahmad, L.; Laânab, L.; Jaber, B.

    2016-05-01

    In this work, we demonstrate that using a glycolic medium, both stable CuO and Cu2O nanoparticles can be elaborated from Cu colloidal particles by adjusting their chemical environment, in particular the acido-basicity of the solution. In this context, the effect of pH on the sol-gel synthesis of Cu2O/CuO NPs was investigated. XRD results confirmed the formation of pure Cu2O with a cubic structure at lower pH (pH ≤ 6), whereas the pure monoclinic CuO was formed at higher pH (pH ≥ 12). TEM image indicates that the as-formed CuO NPs in basic pH are spherical in shape and their average size is found to be in the range of 4.5 nm. However, the as-obtained Cu2O NPs in acid pH are cubical, with an average diameter of about 3 nm, and agglomerated into large spherical particles under the effect of ethylene glycol. Using the UV-Vis spectroscopy, the measured band gap energies of the prepared Cu2O and CuO NPs are 2.07 and 4.08 eV respectively. FTIR results confirm the purity of the synthesized CuO and Cu2O nanoparticles.

  19. Operation of the ISO-DALT system: Seventh edition

    SciTech Connect

    Tollaksen, S.L.; Anderson, N.L.; Anderson, N.G.

    1984-05-01

    The ISO-DALT system of two-dimensional electrophoresis was developed as a series of modifications of the original technique of O'Farrell. We have written a series of recipes and more detailed laboratory procedures that incorporate refinements and ''tricks of the trade'' as they have developed during our use of the system. The present collection is the seventh version in this series and represents the state of art as of May 1984. The seventh edition has been prepared to incorporate the changes that we have found helpful, as well as to add a few new sections such as silver staining, transfer gels, ACIDOs, and BASOs. Although these directions are specific for our laboratory, we hope that they will be helpful in other laboratories as well. Although some disagreement still exists, we recommend that gel patterns be oriented with acid isoelectric points (pIs) to the left and high sodium dodecyl sulfate (SDS) molecular weights at the top. This results in a system of pI and molecular weight values that run according to the Cartesian convention and facilitates the use of the charge and molecular weight standards described herein. 67 refs., 14 figs.

  20. Light-induced copper(II) coordination by a bicyclic tetraaza chelator through a ligand-to-metal charge-transfer reaction.

    PubMed

    Holm-Jørgensen, Jacob R; Jensen, Mikael; Bjerrum, Morten J

    2011-12-19

    To enable utilization of the broad potential of copper isotopes in nuclear medicine, rapid and robust chelation of the copper is required. Bowl adamanzanes (bicyclic tetraaza ligands) can form kinetically stable copper complexes, but they are usually formed at low rates unless high pH values and high temperatures are applied. We have investigated the effects of the variation in the pH, different anions, and UV irradiation on the chelation rate. UV spectra of mixtures of Cu(2+) and [2(4).3(1)]adz in water show the existence of a long-lived two-coordinated copper(II) intermediate (only counting coordinated amine groups) at pH above 6. These findings are supported by pH titrations of mixtures of Cu(2+) and [2(4).3(1)]adz in water. Irradiation of this complex in the ligand-to-metal charge-transfer (LMCT) band by a diode-array spectrophotometer leads to photodeprotonation and subsequently to formation of the four-coordinated copper(II) complex at a rate up to 7800-fold higher at 25 °C than in the dark. Anions in the solution were found to have three major effects: competitive inhibition due to Cu(II) binding anions, inhibition of the photoinduced transchelation from UV-absorbing anions, and photoredox inhibition from acido ligands capable of acting as electron donors in LMCT reactions. Dissolved O(2) was also found to result in photoredox inhibition. PMID:22074363

  1. Assessment of carbonic anhydrase IX expression and extracellular pH in B-cell lymphoma cell line models.

    PubMed

    Chen, Liu Qi; Howison, Christine M; Spier, Catherine; Stopeck, Alison T; Malm, Scott W; Pagel, Mark D; Baker, Amanda F

    2015-05-01

    The expression of carbonic anhydrase IX (CA IX) and its relationship to acidosis in lymphomas has not been widely studied. We investigated the protein expression of CA IX in a human B-cell lymphoma tissue microarray, and in Raji, Ramos and Granta 519 lymphoma cell lines and tumor models, while also investigating the relationship with hypoxia. An imaging method, acidoCEST magnetic resonance imaging (MRI), was used to estimate lymphoma xenograft extracellular pH (pHe). Our results showed that clinical lymphoma tissues and cell line models in vitro and in vivo had moderate CA IX expression. Although in vitro studies showed that CA IX expression was induced by hypoxia, in vivo studies did not show this correlation. Untreated lymphoma xenograft tumor pHe had acidic fractions, and an acidity score was qualitatively correlated with CA IX expression. Therefore, CA IX is expressed in B-cell lymphomas and is qualitatively correlated with extracellular acidosis in xenograft tumor models. PMID:25130478

  2. Synthesis, characterization, reactivity and catalytic activity of oxidovanadium(IV), oxidovanadium(V) and dioxidovanadium(V) complexes of benzimidazole modified ligands.

    PubMed

    Maurya, Mannar R; Bisht, Manisha; Kumar, Amit; Kuznetsov, Maxim L; Avecilla, Fernando; Pessoa, João Costa

    2011-07-14

    The reaction between [V(IV)O(acac)(2)] and the ONN donor Schiff base obtained by the condensation of pyridoxal and 2-aminoethylbenzimidazole (Hpydx-aebmz, I) or 2-aminomethylbenzimidazole (Hpydx-ambmz, II) in equimolar amounts results in the formation of [V(IV)O(acac)(pydx-aebmz)] 1 and [V(IV)O(acac)(pydx-ambmz)] 2, respectively. The aerobic oxidation of the methanolic solution of 1 yielded [V(V)O(2)(pydx-aebmz)] 3 and its reaction with aqueous H(2)O(2) gave the oxidoperoxidovanadium(v) complex, [V(V)O(O(2))(pydx-aebmz)] 4. The formation of 4 in solution is also established by titrations of methanolic solutions of 1 with H(2)O(2). By titrating solutions of 3 and of 4 with aqueous H(2)O(2) several distinct V(V)-pydx-aebmz species also containing the peroxido ligand are detected. The full geometry optimization of all species envisaged was done using DFT methods for suitable model complexes. The (51)V NMR chemical shifts (δ(V)) have also been calculated, the theoretical data being used to support assignments of the experimental chemical shifts. The (51)V hyperfine coupling constants are calculated for 1, the obtained values being in good agreement with the experimental EPR data. Reaction between the V(IV)O(2+) exchanged zeolite-Y and Hpydx-aebmz and Hpydx-ambmz in refluxing methanol, followed by aerial oxidation results in the formation of the encapsulated V(V)O(2)-complexes, abbreviated herein as [V(V)O(2)(pydx-aebmz)]-Y 5 and [V(V)O(2)(pydx-ambmz)]-Y 6. The molecular structure of 1, determined by single crystal X-ray diffraction, confirms its distorted octahedral geometry with the ONN binding mode of the tridentate ligand, with one acetylacetonato group remaining bound to the V(IV)O-centre. Oxidation of styrene is investigated using some of these complexes as catalyst precursors with H(2)O(2) as oxidant. Under optimised reaction conditions for the conversion of styrene in acetonitrile, a maximum of 68% conversion of styrene (with [V(V)O(2)(pydx-aebmz)]-Y) and 65

  3. Mapping of soil-sediment systems contaminations around a metal-ore smelter. The example of Cu in Lubumbashi (RD Congo).

    NASA Astrophysics Data System (ADS)

    Mpundu, M.; Mukobo, R. P.; Kaya, D.; Faucon, M. P.; Andres, L.; Ngongo, M.; Meerts, P. J.; Colinet, G.

    2009-04-01

    The Katanga is famous for its high richness in metal ores, mainly Cu- and Co-minerals. The ore treatments activities lead to metal spreading in the environment which do endanger the viability of ecosystems and human health. The contaminations of soils and sediments around the Gecamines smelter in Lubumbashi have been evaluated through a multi-scale approach. In the first stage, a reference system about the natural contents in soils has been implemented. The main units of the detailed (1:20 000) soil map have been characterized through field observations and laboratory determinations : acido-basic and organic status, particle size distribution, cationic exchange capacity, total contents in Al, Fe, Mn, Cu, Co, Cd, Pb, Zn. An exploratory mapping of soil contaminations (Cu, Co, Cd, Pb, Zn) centered on the Gecamines cheminey was then conducted as a second stage of the approach. Detailed investigations were finally performed in the Gecamines district where signs of soil degradation were the highest. The spatial continuity and the differenciation (C : C0+C ratio) of the studied parameters appeared weak. No clear effect of the dominant wind direction on the spatial distribution of the contaminants could be identified despite a clear degradation of the ecosystem in the area under dominant wind. However the detailed approach showed evidences of (i) significant wind deposits in the Gecamines district, (ii) and local man-made deposits but also (ii) important processes of redistribution in the landscape through erosion/sedimentation or anthropic activities. Our results point out the difficulty to identify the sources of contaminations in an urban environment and stress the need to have approaches with complementary levels of details.

  4. Oxazines: A New Class of Second-Order Nonlinear Optical Switches.

    PubMed

    Beaujean, Pierre; Bondu, Flavie; Plaquet, Aurélie; Garcia-Amorós, Jaume; Cusido, Janet; Raymo, Françisco M; Castet, Frédéric; Rodriguez, Vincent; Champagne, Benoît

    2016-04-20

    A combined experimental-theoretical investigation has revealed that oxazine-based compounds are multiaddressable, multistate, and multifunctional molecular switches exhibiting contrasts of both linear and second-order nonlinear optical properties. The switching properties are particularly large when the substituent is a donor group. In this study, the cleavage of the C-O bond at the junction of the indole and oxazine cycles (of the closed a forms) is acido-triggered, leading to an open form (b(+)) characterized by larger first hyperpolarizabilities (βHRS) and smaller excitation energies than in the closed form. These results are confirmed and interpreted utilizing ab initio calculations that have been carried out on a broad set of compounds to unravel the role of the substituent. With respect to acceptor groups, oxazines bearing donor groups are characterized not only by larger βHRS and βHRS contrast ratios but also by smaller excitation energies, larger opening-induced charge transfer, and reduction of the bond length alternation, as well as smaller Gibbs energies of the opening reaction. Compared to protonated open forms (b(+)), calculations on the zwitterionic open forms (b) have pointed out similarities in the long-wavelength UV/vis absorption spectra, whereas their βHRS values might differ strongly as a function of the substituent. Indeed, the open forms present two NLOphores, the indoleninium-substituent entity and the nitrophenol (present in the protonated open form, b(+)) or nitrophenolate (present in the zwitterionic open form, b) moiety. Then, nitrophenolate displays a larger first hyperpolarizability than nitrophenol and the β tensor of the two entities might reinforce or cancel each other. PMID:26996994

  5. 13,16-Dimethyl Octacosanedioic Acid (iso-Diabolic Acid), a Common Membrane-Spanning Lipid of Acidobacteria Subdivisions 1 and 3 ▿ †

    PubMed Central

    Sinninghe Damsté, Jaap S.; Rijpstra, W. Irene C.; Hopmans, Ellen C.; Weijers, Johan W. H.; Foesel, Bärbel U.; Overmann, Jörg; Dedysh, Svetlana N.

    2011-01-01

    The distribution of membrane lipids of 17 different strains representing 13 species of subdivisions 1 and 3 of the phylum Acidobacteria, a highly diverse phylum of the Bacteria, were examined by hydrolysis and gas chromatography-mass spectrometry (MS) and by high-performance liquid chromatography-MS of intact polar lipids. Upon both acid and base hydrolyses of total cell material, the uncommon membrane-spanning lipid 13,16-dimethyl octacosanedioic acid (iso-diabolic acid) was released in substantial amounts (22 to 43% of the total fatty acids) from all of the acidobacteria studied. This lipid has previously been encountered only in thermophilic Thermoanaerobacter species but bears a structural resemblance to the alkyl chains of bacterial glycerol dialkyl glycerol tetraethers (GDGTs) that occur ubiquitously in peat and soil and are suspected to be produced by acidobacteria. As reported previously, most species also contained iso-C15 and C16:1ω7C as major fatty acids but the presence of iso-diabolic acid was unnoticed in previous studies, most probably because the complex lipid that contained this moiety was not extractable from the cells; it could only be released by hydrolysis. Direct analysis of intact polar lipids in the Bligh-Dyer extract of three acidobacterial strains, indeed, did not reveal any membrane-spanning lipids containing iso-diabolic acid. In 3 of the 17 strains, ether-bound iso-diabolic acid was detected after hydrolysis of the cells, including one branched GDGT containing iso-diabolic acid-derived alkyl chains. Since the GDGT distribution in soils is much more complex, branched GDGTs in soil likely also originate from other (acido)bacteria capable of biosynthesizing these components. PMID:21515715

  6. [Folate and iron in fertile age women from a Venezuelan community affected by incidence of neural tube defects].

    PubMed

    Mariela, Montilva; Jham, Papale; Nieves, García-Casal María; Yelitza, Berné; Yudith, Ontiveros; Lourdes, Durán

    2010-06-01

    The objective of this transversal study was to determine folate and iron nutritional status of women in fertile age from Municipio Jiménez, Lara State, Venezuela. The sampling was probabilistic by conglomerates from the urban and rural areas, selecting 15 conglomerates from which women between 12 and 45 years (269), were studied. After signing informed consent, participating were interviewed for personal data, antecedents related to folate and iron, socioeconomic data (Graffar-Mendez Castellano method and unsatisfied basic needs). In blood sample was determined Hemoglobin, and Erythrocytic Folate (FE). Serum was obtained to determine Ferritin and Serum Folate (FS). 53.53% of the sample presented low FS levels, 10.78% were FS deficient. Severe FE deficiency was present in 80.7% of the cases, moderate deficiency affected 5.9%. For both tests, median was higher for women in treatment with Acido Fólico or pregnant (p = 0.000), median for FE was higher for adults (p = 0.001) and in non poor women (p = 0.011). There were no significant differences for coffee, alcohol, anticonceptive consumption, urban or rural resident or socioeconomic strata. The prevalence of anemia was 11.2% being significantly more frequent in adults than in adolescents (p = 0.029) and in urban women (p = 0.042). Low ferritin were found in 37.3% of the sample, the effect of different variables was not statistically significant. In conclusion, there is a high prevalence of iron and folate deficiencies in women of fertile age from Municipio Jiménez, which could constitute a conditioning factor for the appearance of neural tube defects. PMID:21427880

  7. pH as a Driver for Ammonia-Oxidizing Archaea in Forest Soils.

    PubMed

    Stempfhuber, Barbara; Engel, Marion; Fischer, Doreen; Neskovic-Prit, Ganna; Wubet, Tesfaye; Schöning, Ingo; Gubry-Rangin, Cécile; Kublik, Susanne; Schloter-Hai, Brigitte; Rattei, Thomas; Welzl, Gerhard; Nicol, Graeme W; Schrumpf, Marion; Buscot, Francois; Prosser, James I; Schloter, Michael

    2015-05-01

    In this study, we investigated the impact of soil pH on the diversity and abundance of archaeal ammonia oxidizers in 27 different forest soils across Germany. DNA was extracted from topsoil samples, the amoA gene, encoding ammonia monooxygenase, was amplified; and the amplicons were sequenced using a 454-based pyrosequencing approach. As expected, the ratio of archaeal (AOA) to bacterial (AOB) ammonia oxidizers' amoA genes increased sharply with decreasing soil pH. The diversity of AOA differed significantly between sites with ultra-acidic soil pH (<3.5) and sites with higher pH values. The major OTUs from soil samples with low pH could be detected at each site with a soil pH <3.5 but not at sites with pH >4.5, regardless of geographic position and vegetation. These OTUs could be related to the Nitrosotalea group 1.1 and the Nitrososphaera subcluster 7.2, respectively, and showed significant similarities to OTUs described from other acidic environments. Conversely, none of the major OTUs typical of sites with a soil pH >4.6 could be found in the ultra- and extreme acidic soils. Based on a comparison with the amoA gene sequence data from a previous study performed on agricultural soils, we could clearly show that the development of AOA communities in soils with ultra-acidic pH (<3.5) is mainly triggered by soil pH and is not influenced significantly by the type of land use, the soil type, or the geographic position of the site, which was observed for sites with acido-neutral soil pH. PMID:25501889

  8. Arthrite à pneumocoque chez un adulte immunocompétent

    PubMed Central

    Chemsi, Hicham; Chadli, Maryama; Sekhsokh, Yassine

    2015-01-01

    Les infections à pneumocoques sont avant tout respiratoires, ORL et méningées. Les infections ostéoarticulaires à pneumocoque ont la particularité de survenir dans moins de 20% des cas chez l'adulte sain. Habituellement, un ou plusieurs facteurs favorisants sont retrouvés. Toutefois, nous rapportons lors de cette observation le cas d'une arthrite à Streptococcus pneumoniae chez un adulte immunocompétent sans facteurs prédisposant. Patient âgé de 66 ans, diabétique de type II, a été hospitalisé pour une décompensation acido-cétosique et une monoarthrite du genou droit. Ce patient était fébrile (39°C) et présentait un genou droit inflammatoire en flexion avec rougeur et chaleur locale et un choc rotulien. Une ponction articulaire avec d'autres examens ont été réalisés pour confirmation d'une arthrite septique à pneumocoque. Le résultat de la ponction articulaire réalisée a montré un liquide jaune citron trouble avec 480 000 leucocytes/mm3 à prédominance polynucléaires neutrophiles. L'examen direct a montré des coccis à Gram positif en diplocoque, la culture a permis d'isoler un Streptococcus pneumoniae sensible à la pénicilline G. L’évolution clinique et biologique de l'arthrite du genou était favorable. Un déficit immunitaire, un asplénisme anatomique ou fonctionnel peuvent être en cause. L'alcoolisme est un facteur favorisant mais le mécanisme n'est pas clairement élucidé. La présence de matériel prothétique, peut favoriser une localisation septique. Ces facteurs de risque doivent être systématiquement recherchés, notamment en cas d'infection grave ou récidivante, une antibioprophylaxie ou une vaccination pouvant être proposées chez les sujets à haut risque. PMID:26327976

  9. Prise en charge diagnostique et thérapeutique de la tuberculose ganglionnaire en Tunisie

    PubMed Central

    Ben Brahim, Hajer; Kooli, Ikbel; Aouam, Abir; Toumi, Adnene; Loussaief, Chawki; Koubaa, Jamel; Chakroun, Mohamed

    2014-01-01

    La tuberculose ganglionnaire est la localisation extra-pulmonaire la plus fréquente de la tuberculose. Nous nous proposons dans ce travail d’étudier les modalités diagnostiques, thérapeutiques et évolutives de cette localisation. Il s'agit d'une étude rétrospective portant sur 100 cas de tuberculose ganglionnaire. L’âge moyen était de 35 ± 15 ans (15-85 ans). Aucun malade n’était VIH positif. L'aire cervicale était la plus touchée (93 cas). L'intradermo-réaction à la tuberculine était positive dans 76/91 cas (83,5%). L'examen bactériologique des prélèvements au niveau des ganglions atteints avait mis en évidence des bacilles acido-alcoolo-résistants à l'examen direct dans 2/31 cas (6,4%) et la culture avait isolé Mycobacteruim tuberculosis dans 1/31 cas (3,2%). La cytoponction ganglionnaire (FNAC) était évocatrice de tuberculose dans 35/42 cas (83,3%). La biopsie ganglionnaire était réalisée dans 69 cas et avait permis de retenir le diagnostic de tuberculose dans tous les cas. La FNAC, comparativement à la biopsie, avait permis de raccourcir significativement le délai de la prise en charge (15,1 vs 22,8 jours; p=0,001) et la durée d'hospitalisation (17,3 vs 24,6; p=0,004). La durée moyenne du traitement antituberculeux était de 9,8 ± 4,6 mois (7 à 44 mois). Le traitement chirurgical initial avait raccourci significativement la durée du traitement médical. Il n'avait pas d'impact sur le taux de guérison. Nous avons noté 10 cas de réponse paradoxale aux antituberculeux, quatre cas de résistance clinique et une rechute dans deux cas. La tuberculose ganglionnaire pose un problème diagnostique et thérapeutique. La microbiologie est d'un faible apport. La FNAC est un moyen diagnostique très utiles dans les pays endémiques et à faibles ressources. Un traitement médical seul permet d’éviter les inconvénients de la chirurgie. PMID:25829976

  10. Using short-lived nuclides of the U- and Th-series to probe the kinetics of colloid migration in forested soils

    NASA Astrophysics Data System (ADS)

    Rihs, Sophie; Prunier, Jonathan; Thien, Bruno; Lemarchand, Damien; Pierret, Marie-Claire; Chabaux, François

    2011-12-01

    The recent chemical dynamics of a podzolic forest soil section (from the Strengbach watershed, France) was investigated using U- and Th-series nuclides. Analyses of ( 238U), ( 230Th), ( 226Ra), ( 232Th), ( 228Ra) and ( 228Th) activities in the soil particles, the seepage waters, and the mature leaves of the beech trees growing on this soil were performed by TIMS or gamma spectrometry. The simultaneous analysis of the different soil ( sl) compartments allows to demonstrate that a preferential Th leaching over Ra must be assumed to explain the ( 226Ra/ 230Th), ( 228Ra/ 232Th) and ( 228Th/ 228Ra) disequilibria recorded in the soil particles. The overall Ra- and Th- transfer schemes are entirely consistent with the prevailing acido-complexolysis weathering mechanism in podzols. Using a continuous open-system leaching model, the ( 226Ra/ 230Th) and ( 228Ra/ 232Th) disequilibria measured in the different soil layers enable dating of the contemporary processes occurring in this soil. In this way, we have determined that a preferential Th-leaching from the shallow Ah horizon, due to a strong complexation with organic colloids, began fairly recently (18 years ago at most). The continual increase in pH recorded in precipitations over the last 20 years is assumed to be the cause of this enhanced organic complexation. A lower soil horizon (50-60 cm) is also affected by preferential Th leaching, though lasting over several centuries at least, with a much smaller leaching rate. The migration of Th isotopes through this soil section might hence be used as a tracer for the organic colloids migration and the induced radioactive disequilibria demonstrate to be useful for assessing the colloidal migration kinetics in a forested soil. Ra and Th isotopic ratios also appear to be valuable tracers of some mineral-water-plant interactions occurring in soil. The ( 228Ra/ 226Ra) ratio enables discrimination of the Ra flux originating from leaf degradation from that originating from mineral

  11. Methanotrophic activity and diversity of methanotrophs in volcanic geothermal soils at Pantelleria (Italy)

    NASA Astrophysics Data System (ADS)

    Gagliano, A. L.; D'Alessandro, W.; Tagliavia, M.; Parello, F.; Quatrini, P.

    2014-10-01

    Volcanic and geothermal systems emit endogenous gases by widespread degassing from soils, including CH4, a greenhouse gas twenty-five times as potent as CO2. Recently, it has been demonstrated that volcanic or geothermal soils are not only a source of methane, but are also sites of methanotrophic activity. Methanotrophs are able to consume 10-40 Tg of CH4 a-1 and to trap more than 50% of the methane degassing through the soils. We report on methane microbial oxidation in the geothermally most active site of Pantelleria (Italy), Favara Grande, whose total methane emission was previously estimated at about 2.5 Mg a-1 (t a-1). Laboratory incubation experiments with three top-soil samples from Favara Grande indicated methane consumption values of up to 59.2 nmol g-1 soil d.w. h-1. One of the three sites, FAV2, where the highest oxidation rate was detected, was further analysed on a vertical soil profile, the maximum methane consumption was measured in the top-soil layer, and values greater than 6.23 nmol g-1 h-1 were still detected up to a depth of 13 cm. The highest consumption rate was measured at 37 °C, but a still detectable consumption at 80 °C (> 1.25 nmol g-1 h-1) was recorded. The soil total DNA extracted from the three samples was probed by Polymerase Chain Reaction (PCR) using standard proteobacterial primers and newly designed verrucomicrobial primers, targeting the unique methane monooxygenase gene pmoA; the presence of methanotrophs was detected at sites FAV2 and FAV3, but not at FAV1, where harsher chemical-physical conditions and negligible methane oxidation were detected. The pmoA gene libraries from the most active site (FAV2) pointed to a high diversity of gammaproteobacterial methanotrophs, distantly related to Methylocaldum-Metylococcus genera, and the presence of the newly discovered acido-thermophilic Verrucomicrobia methanotrophs. Alphaproteobacteria of the genus Methylocystis were isolated from enrichment cultures under a methane

  12. Overloaded elution band profiles of ionizable compounds in reversed-phase liquid chromatography: Influence of the competition between the neutral and the ionic species

    SciTech Connect

    Gritti, Fabrice; Guiochon, Georges A

    2008-01-01

    The parameters that affect the shape of the band profiles of acido-basic compounds under moderately overloaded conditions (sample size less than 500 nmol for a conventional column) in RPLC are discussed. Only analytes that have a single pK{sub a} are considered. In the buffer mobile phase used for their elution, their dissociation may, under certain conditions, cause a significant pH perturbation during the passage of the band. Two consecutive injections (3.3 and 10 {micro}L) of each one of three sample solutions (0.5, 5, and 50 mM) of ten compounds were injected on five C{sub 18}-bonded packing materials, including the 5 {micro}m Xterra-C{sub 18} (121 {angstrom}), 5 {micro}m Gemini-C{sub 18} (110 {angstrom}), 5 {micro}m Luna-C{sub 18}(2) (93 {angstrom}), 3.5 {micro}m Extend-C{sub 18} (80 {angstrom}), and 2.7 {micro}m Halo-C{sub 18} (90 {angstrom}). The mobile phase was an aqueous solution of methanol buffered at a constant {sub W}{sup W}pH of 6, with a phosphate buffer. The total concentration of the phosphate groups was constant at 50 mM. The methanol concentration was adjusted to keep all the retention factors between 1 and 10. The compounds injected were phenol, caffeine, 3-phenyl 1-propanol, 2-phenyl butyric acid, amphetamine, aniline, benzylamine, p-toluidine, procainamidium chloride, and propranololium chloride. Depending on the relative values of the analyte pK{sub a} and the buffer solution pH, these analytes elute as the neutral, the cationic, or the anionic species. The influence of structural parameters such as the charge, the size, and the hydrophobicity of the analytes on the shape of its overloaded band profile is discussed. Simple but general rules predict these shapes. An original adsorption model is proposed that accounts for the unusual peak shapes observed when the analyte is partially dissociated in the buffer solution during its elution.

  13. Methanotrophic activity and bacterial diversity in volcanic-geothermal soils at Pantelleria island (Italy)

    NASA Astrophysics Data System (ADS)

    Gagliano, A. L.; D'Alessandro, W.; Tagliavia, M.; Parello, F.; Quatrini, P.

    2014-04-01

    Volcanic and geothermal systems emit endogenous gases by widespread degassing from soils, including CH4, a greenhouse gas twenty-five times as potent as CO2. Recently, it has been demonstrated that volcanic/geothermal soils are source of methane, but also sites of methanotrophic activity. Methanotrophs are able to consume 10-40 Tg of CH4 a-1 and to trap more than 50% of the methane degassing through the soils. We report on methane microbial oxidation in the geothermally most active site of Pantelleria island (Italy), Favara Grande, whose total methane emission was previously estimated in about 2.5 t a-1. Laboratory incubation experiments with three top-soil samples from Favara Grande indicated methane consumption values up to 950 ng g-1 dry soil h-1. One of the three sites, FAV2, where the highest oxidation rate was detected, was further analysed on a vertical soil profile and the maximum methane consumption was measured in the top-soil layer but values > 100 ng g-1 h-1 were maintained up to a depth of 15 cm. The highest consumption rate was measured at 37 °C, but a still recognizable consumption at 80 °C (> 20 ng g-1 h-1) was recorded. In order to estimate the bacterial diversity, total soil DNA was extracted from Favara Grande and analysed using a Temporal Temperature Gradient gel Electrophoresis (TTGE) analysis of the amplified bacterial 16S rRNA gene. The three soil samples were probed by PCR using standard proteobacterial primers and newly designed verrucomicrobial primers targeting the unique methane monooxygenase gene pmoA; the presence of methanotrophs was detected in sites FAV2 and FAV3, but not in FAV1, where harsher chemical-physical conditions and negligible methane oxidation were detected. The pmoA gene libraries from the most active site FAV2 pointed out a high diversity of gammaproteobacterial methanotrophs distantly related to Methylococcus/Methylothermus genera and the presence of the newly discovered acido-thermophilic methanotrophs

  14. The role of extremophile in the redox reaction of Fe and As relating with the formation of secondary phase mineral in extreme environment, Norris Geyser Basin, Yellowstone National Park, USA

    NASA Astrophysics Data System (ADS)

    Koo, T. H.; Kim, J. Y.; Park, K. R.; Jung, D. H.; Geesey, G. G.; Kim, J. W.

    2015-12-01

    Redox reaction associated with microbial elemental respiration is a ubiquitous process in sediments and suspended particles at various temperatures or pH/Eh conditions. Particularly, changes in elemental redox states (structural or dissolved elemental form) induced by microbial respiration result in the unexpected biogeochemical reactions in the light of biotic/abiotic mineralization. The objective of the present study is, therefore to investigate the secondary phase mineralization through a-/biogeochemical Fe and As redox cycling in the acido-hyperhtermal Norris Geyser Basin (NGB) in Yellowstone National Park, USA, typical of the extreme condition. X-ray diffraction, scanning electron microscope with energy dispersive x-ray spectroscopy, X-ray absorption near edge structure, inductively coupled plasma-atomic emission spectrometer and liquid chromatography with ICP-mass spectroscopy with filtrated supernatant were performed for the mineralogical and hydro-geochemical analysis. The clay slurry collected from the active hot-spring of the NGB area (pH=3.5 and Temperature=78 ℃) was incubated with ("enrichment") or without the growth medium ("natural"). The control was prepared in the same condition except adding the glutaraldehyde to eliminate the microbial activity. The secondary phase mineral formation of the oxidative phase of Fe and As, and K identified as 'Pharmacosiderite' only appeared in the enrichment set suggesting a role of extremophiles in the mineral formation. The considerable population of Fe-oxidizer (Metallosphera yellowstonensis MK-1) and As-oxidizer (Sulfurihydrogenibium sp.) was measured by phylogenetic analysis in the present study area. The inhibition of As-oxidation in the low pH conditions was reported in the previous study, however the As-redox reaction was observed and consequently, precipitated the Pharmacosiderite only in the enrichment set suggesting a biotic mineralization. The present study collectively suggests that the microbial

  15. Effects of Long-Term Acid-Mine Drainage Contamination on Diversity and Activity of Sulfate-Reducing Bacteria in a Natural Salt Marsh.

    NASA Astrophysics Data System (ADS)

    Moreau, J. W.; Banfield, J. F.

    2003-12-01

    -grained black muds that are distinguishable from coarser pyrite cinders, and exhibit a noticeably strong sulfide odor. Aero- and halo-tolerant SRB were enriched from circumneutral pH cores, and we hypothesize that acido-tolerant SRB may also be present. Analysis of restriction fragment length polymorphism of whole community 16S rDNA extracted from each core shows an expected increase in diversity between acidic and circumneutal sediments, and clone libraries from both contaminated and uncontaminated marsh sediments are being compared to assess the impact of long-term contamination. References: Webb et al. 1998, J. Appl. Microbio., 84, 240-248; Moreau et al. 2003, Amer. Min., in review; URS Corp. 2001, Report 51.09967067.00.

  16. Zinc, cadmium, and copper mobility and accumulation in reeds (Phragmites australis) in urban sediments from two stormwater infiltration basins

    NASA Astrophysics Data System (ADS)

    Bedell, J.-P.; Saulais, S.; Delolme, C.

    2012-04-01

    Infiltration basins are stormwater management techniques that are widely used to reduce stormwater volume. The settling of stormwater particles leads to a contaminated sediment layer at the basin surface. Phragmites australis used in constructed wetlands are widely present in infiltration basins. Such plant can play a role on the fate of heavy metals either directly by their uptake or indirectly by modification of physico-chemical characteristics of the sediment. The aim of this study is to assess Zn, Cd and Cu potential mobility and their bioaccumulation by reeds during plant's growth in urban sediments offering two different geochemical contexts. Methodology is based on the monitoring (in june, august and december) of physico-chemical characteristics of sediment deposit in two basins. These basins, "Minerve" and "Grézieu", located on both sides of Lyon city are characteristic of two different geochemical context. "Minerve" is in the east and "Grézieu" in the west part. The geology of the eastern part of Lyon is characterized by carbonated fluvio-glacial deposits. In the western part, the subsoil is mainly composed of gneiss and granit. Moreover, 20 cm of gravel and a sand layer were initially added at the surface of the "Grézieu" basin. In "Minerve", a clay material was initially added and a filter trench was built along the basin to allow water infiltration. We characterized the sediment deposit by the identification of their geochemical characteristics (Zn, Cu, Cd, total content, pH, CEC, C/N, carbonates and major elements contents …). Then we studied the potential mobility of the three metals by single chemical extraction (CaCl2 for the exchangeable phase, acetate buffer for the acido-soluble phase and diethylenetriamine-pentaacetic acid (DTPA) for the fraction associated to the organic matter). The accumulation of Zn, Cd and Cu in aerial parts and roots of the reeds was also measured. The results show clearly that "Grézieu" sediment is more enriched in

  17. Facteurs de risque de mortalité par tuberculose pulmonaire

    PubMed Central

    Janah, Hicham; Souhi, Hicham; Kouismi, Hatim; Mark, Karima; Zahraoui, Rachida; Benamor, Jouda; Soualhi, Mona; Bourkadi, Jamal Eddine

    2014-01-01

    La tuberculose est une maladie infectieuse transmissible provoquée par myco-bacterium tuberculosis (bacille de Koch ou BK). Elle représente, selon les estimations del'Organisation Mondiale de la Santé (OMS), l'une des pathologies infectieuses causant le plus de décès au niveau mondial avec plus de 1 million de décès par an. Pour déterminer les facteurs de risque de mortalité au cours de la tuberculose pulmonaire à microscopie positive nous avons mené une étude rétrospective portant sur tous les cas de tuberculose pulmonaire à microscopie positive et qui étaient décédés au cours de leur hospitalisation. Cette étude a colligé 1803 cas de tuberculose sur une période de 2 ans et demi dont 46 sont décédés. La prévalence de décès est de 2,55%. La population se répartit en 32 hommes et 14 femmes. L’âge moyen était de 53ans ± 17 ans. Le tabagisme était retrouvé chez la moitié des cas. Une comorbidité était retrouvée dans 43%, avec 17% de diabète. Le délai de diagnostic avait une médiane de 60 jours avec percentile (30j; 105j). La symptomatologie clinique était dominée par la toux, la dyspnée et les expectorations soit respectivement: 97,8%, 69,6% et 67,4% des cas. Sur le plan radiologique les lésions étaient diffuses et bilatérales dans 76,1% des cas. Tous les patients étaient mis sous SRHZ. 11% avaient présenté une toxicité aux antibacillaires (de type hépatiques dans 3 cas et neurologiques dans 2 cas). Le délai médian de décès était de 8,5 jours (5j; 17j). Les causes de décès retrouvées étaient: Une hépatite fulminante (3 cas), une décompensation acido-cétosique (3 cas), un SDRA (2 cas), des hémoptysies foudroyantes (2 cas), et respectivement un cas secondaire à une décompensation de BPCO, une décompensation cardiaque, une hypoglycémie et un tableau d'anasarque. Cette étude suggère que le terrain, le retard diagnostique et les effets secondaires du traitement sont les principaux facteurs de risque de

  18. Peak shapes of acids and bases under overloaded conditions in reversed-phase liquid chromatography, with weakly buffered mobile phases of various pH: A thermodynamic interpretation

    SciTech Connect

    Gritti, Fabrice; Guiochon, Georges A

    2009-01-01

    We measured overloaded band profiles for a series of nine compounds (phenol, caffeine, 3-phenyl 1-propanol, 2-phenylbutyric acid, amphetamine, aniline, benzylamine, p-toluidine, and procainamidium chloride) on columns packed with four different C{sub 18}-bonded packing materials: XTerra-C{sub 18}, Gemini-C{sub 18}, Luna-C{sub 18}(2), and Halo-C{sub 18}, using buffered methanol-water mobile phases. The {sub W}{sup S}pH of the mobile phase was increased from 2.6 to 11.3. The buffer concentration (either phosphate, acetate, or carbonate buffers) was set constant at values below the maximum concentration of the sample in the band. The influence of the surface chemistry of the packing material on the retention and the shape of the peaks was investigated. Adsorbents having a hybrid inorganic/organic structure tend to give peaks exhibiting moderate or little tailing. The retention and the shape of the band profiles can easily be interpreted at {sub W}{sup S}pHs that are well above or well below the {sub W}{sup S}pK{sub a} of the compound studied. In contrast, the peak shapes in the intermediary pH range (i.e., close to the compound {sub W}{sup S}pK{sub a}) have rarely been studied. These shapes reveal the complexity of the competitive adsorption behavior of couples of acido-basic conjugated compounds at {sub W}{sup S}pHs that are close to their {sub W}{sup S}pK{sub a}. They also reveal the role of the buffer capacity on the resulting peak shape. With increasing {sub W}{sup S}pH, the overloaded profiles are first langmuirian (isotherm type I) at low {sub W}{sup S}pHs, they become S-shaped (isotherm type II), then anti-langmuirian (isotherm type III), S-shaped again at intermediate {sub W}{sup S}pHs, and finally return to a langmuirian shape at high {sub W}{sup S}pHs. A new general adsorption isotherm model that takes into account the dissociation equilibrium of conjugated acidic and basic species in the bulk mobile phase accounts for these transient band shapes. An

  19. Effet de la substitution du cuivre par du lithium sur les proprietes de l'oxyde spinelle lithium(x)cuivre(y-x)cobalt(3-y)oxygen(4) etudie pour l'electrocatalyse de la reaction de degagement de l'oxygene en milieu alcalin

    NASA Astrophysics Data System (ADS)

    Fatih, Khalid

    L'electrolyse de l'eau demeure la seule technologie industrielle de generation de l'hydrogene et de l'oxygene tres purs sans rejet de CO2 dans l'atmosphere, ce qui le rend tres attrayant par rapport a la combustion de carburants fossiles qui provoque presentement de serieux problemes environnementaux. Dans le but d'ameliorer le rendement de ce procede, nous avons developpe de nouveaux materiaux d'anode peu couteux, a base de l'oxyde mixte CuyCo3-yO 4, qui possedent une cinetique rapide pour la reaction de degagement de l'oxygene (RDO). Cette reaction suscite un interet particulier en raison de la surtension d'activation relativement elevee a l'anode qui cause la principale perte de rendement du procede. Une etude systematique a ete effectuee sur la substitution du Cu par du Li (0 a 40%), afin d'elucider les proprietes electrocatalytiques des oxydes LixCuy-xCo3-yO4. Ces oxydes, prepares sous forme de poudres par decomposition thermique des nitrates precurseurs entre 300 et 500°C, ont montre (DRX et FTIR) une structure spinelle inverse non-stcechiometrique avec une diminution du volume de la maille cristalline. La surface specifique par BET est d'environ 6 m2 g-1. Le pcn, obtenu par titrage acido-basique, a indique une diminution de la force du lien M-OH avec le taux du Li dans l'oxyde. Les analyses par XPS, realisees sur des films d'oxyde prepares par nebulisation reactive sur un substrat lisse de nickel, revelent un enrichissement de la surface en Cu a partir de 30% Li, et la presence des cations de surface Co2+, Co3+, Cu +, Cu2+ et Cu3+. La concentration de ce dernier montre un maximum a 10 et 20% Li. Suite a la substitution du Cu par du Li, la compensation de la charge serait assuree principalement par la formation d'especes Cu3+ pour les oxydes contenant jusqu'a 20% Li, et par la formation d'especes Co3+ aux taux de substitution superieurs. Les micrographies MEB montrent une morphologie hemispherique des particules d'oxyde reparties uniformement sur le substrat

  20. Assessment of a sequential extraction protocol by examining solution chemistry and mineralogical evolution

    NASA Astrophysics Data System (ADS)

    Maubec, Nicolas; Pauwels, Hélène; Noël, Hervé; Bourrat, Xavier

    2015-04-01

    of them are able to leach several solid phases. In this context, the aim of the present study is to investigate the effectiveness and the selectivity of different reagents for metal extraction from target geochemical fraction. It is based on solid analyses with the use of X-ray diffraction and a scanning electron microscopy (SEM) coupled to a microRaman spectrometer in conjunction with chemical analyses of extracting solutions at each step. This methodology provides the opportunity to assess more accurately the effect of each reagent. The study focuses on extraction of Cu and Zn from sediment samples collected at two sites from river banks and characterized by presence of Quartz, Feldspar K, Micas, Kaolinite but with differences regarding accessory phases (pyrite, organic matter, iron oxy- hydroxide, calcite). The interaction of the samples with eight different reagents was assessed and compared (Ca(NO3)2 and CaCl2 for the exchangeable fraction; buffered solutions of sodium acetate/acetic acid at pH = 5.5 and pH = 5 for the acido-soluble fraction; hydroxylamine hydrochloride and a solution of ammonium oxalate/oxalic acid for reducible fraction; hydrogen peroxide and sodium hypochlorite for the oxidizable fraction. In-depth characterization of solid residue at each step allowed proposing the best protocol for both metals. Anderson, P., Davidson, C. M., Duncan, A. L., Littlejohn, D., Ure, A. M., and Garden, L. M. (2000). Column leaching and sorption experiments to assess the mobility of potentially toxic elements in industrially contaminated land. Journal of Environmental Monitoring, 2. Arey, J. S., Seaman, J. C., and Bertsch, P. M. (1999). Immobilization of uranium in contaminated sediments by hydroxyapatite addition. Environmental Science & Technology, 33, 337-342. Brannon, J. M., and Patrick, W. H. (1987). Fixation, transformation, and mobilization of arsenic in sediments.Environmental Science & Technology, 21, 450-459. Cornu, S., and Clozel, B. (2000). Extractions

  1. Assessment of a sequential extraction protocol by examining solution chemistry and mineralogical evolution

    NASA Astrophysics Data System (ADS)

    Maubec, Nicolas; Pauwels, Hélène; Noël, Hervé; Bourrat, Xavier

    2015-04-01

    of them are able to leach several solid phases. In this context, the aim of the present study is to investigate the effectiveness and the selectivity of different reagents for metal extraction from target geochemical fraction. It is based on solid analyses with the use of X-ray diffraction and a scanning electron microscopy (SEM) coupled to a microRaman spectrometer in conjunction with chemical analyses of extracting solutions at each step. This methodology provides the opportunity to assess more accurately the effect of each reagent. The study focuses on extraction of Cu and Zn from sediment samples collected at two sites from river banks and characterized by presence of Quartz, Feldspar K, Micas, Kaolinite but with differences regarding accessory phases (pyrite, organic matter, iron oxy- hydroxide, calcite). The interaction of the samples with eight different reagents was assessed and compared (Ca(NO3)2 and CaCl2 for the exchangeable fraction; buffered solutions of sodium acetate/acetic acid at pH = 5.5 and pH = 5 for the acido-soluble fraction; hydroxylamine hydrochloride and a solution of ammonium oxalate/oxalic acid for reducible fraction; hydrogen peroxide and sodium hypochlorite for the oxidizable fraction. In-depth characterization of solid residue at each step allowed proposing the best protocol for both metals. Anderson, P., Davidson, C. M., Duncan, A. L., Littlejohn, D., Ure, A. M., and Garden, L. M. (2000). Column leaching and sorption experiments to assess the mobility of potentially toxic elements in industrially contaminated land. Journal of Environmental Monitoring, 2. Arey, J. S., Seaman, J. C., and Bertsch, P. M. (1999). Immobilization of uranium in contaminated sediments by hydroxyapatite addition. Environmental Science & Technology, 33, 337-342. Brannon, J. M., and Patrick, W. H. (1987). Fixation, transformation, and mobilization of arsenic in sediments.Environmental Science & Technology, 21, 450-459. Cornu, S., and Clozel, B. (2000). Extractions

  2. The extreme environments and their microbes as models for extraterrestrial life

    NASA Astrophysics Data System (ADS)

    Seckbach, J.; Oren, A.; Chela-Flores, J.

    2008-09-01

    Life exists almost everywhere on Earth. Presence of liquid water is a prerequisite for life (Oren, 2008). Living organisms are not only found in `normal' habitats (from the anthropocentric view). Many types, especially of microorganisms, not only tolerate harsh environmental conditions, but even thive in them. Such organisms that resist very harsh physical and chemical conditions in their habitats are termed `extremophiles'. Some extremophilic microorganisms are able to overcome more than one type of extreme conditions in their environment. For example, some `polyextremophiles' grow under hundreds of atmospheres of hydrostatic pressure (barophiles) and at very low, or alternatively at very high temperatures. In many hot springs there are acido-thermophiles that tolerate elevated temperatures and very low pH levels (e.g. the Cyanidium caldarium group, see Seckbach 1994). Members of Cyanidium are able to thrive in pure CO2, a condition not tolerated by most algae (Seckbach et al., 1970). Some thermophilic Archaea grow at temperatures up to 1130C and possibly even higher. In the Arctic and Antarctic regions and in the permafrost region in Siberia there are cold-loving microorganisms (psychrophiles) which are able to grow at -200C. Many types of Bacteria and Archaea tolerate extreme dryness, and spores of Bacillus and relatives that have been encapsulated within salt crystals may have survived in a dormant state for thousands and even millions of years, and still can be revived today. Other extremophiles tolerate salt concentrations up to saturation. Halophilic microorganisms such as found in the Dead Sea or in the Great Salt Lake have developed different strategies to cope with the high osmotic pressure of their environment. Some (e.g. the unicellular green alga Dunaliella salina) balance the salts in their medium by accumulating organic compounds such as glycerol. Others (halophilic Archaea of the order Halobacteriales, as well as a few representatives of the